Picky Plants: Do They "Choose" The Best Fungal Partner?
ScienceDaily (Aug. 9, 2001) — MADISON, Wis. --- Every time we make a choice, whether between job offers in two different cities or about what to have for dinner, evaluating the costs and benefits of each option is part of the process. Researchers at the University of Michigan are finding that the ability to actively select one option over another may no longer be reserved for higher animals; in fact, plants may make choices too.
Many plants form partnerships with fungi that live in the soil. Attached to the plant's roots, the fungus provides the plant with nutrients needed for growth---usually phosphorous—and the plant provides the fungus with something it needs, usually carbon. Many plants show increased growth when they team up with a fungus, but all fungi are not created equal. Depending on the environment, one fungus may cost the plant more or less carbon in exchange for the nutrients the fungus makes available to the plant.
And according to a paper to be presented at the annual meeting of the Ecological Society of America on Aug. 8 by U-M doctoral student Miroslav Kummel, "plants may be actively 'choosing' the species of fungus that supports the highest growth for the plant."
Depending on environmental factors such as soil type or amount of light, fungi differ in their effects on plant growth, and a plant living in the shade may be better off with a different fungus than a plant living in the sun. "Of course this is the result of long-term selection," says Deborah Goldberg, a professor of ecology and evolutionary biology and one of Kummel's faculty advisers, "but the consequences are the same as if it were a cognitive choice, and that's pretty cool."
Kummel looked at the distribution pattern of different types of fungi growing on balsam fir seedlings in an area with light conditions ranging from full sun to full shade. He found that a fir seedling living in the shade associates with a different fungus than a fir seedling living in the sun, and that it teams up with the fungus that "costs" the least, while still benefiting the plant.
The mechanism by which the plant "chooses" the fungus is not yet known. It could result from the plant selectively aborting roots that associate with the more "expensive" fungus or from selective growth of new root tips. By isolating pure cultures of different fungi to more closely examine the exchange of nutrients between plant and fungus, Kummel hopes to unravel this mechanism. These experiments are in progress. Ultimately, Kummel's work could have implications for the timber industry, as many of our pulp crops and commercial hardwoods also form associations with fungi.
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Adapted from materials provided by University Of Michigan.
Sunday, June 29, 2008
Plant-Fungal Symbiosis Found In High-Heat Extreme Environment
Plant-Fungal Symbiosis Found In High-Heat Extreme Environment
ScienceDaily (Nov. 27, 2002) — ARLINGTON, Va. -- Researchers examining plants growing in the geothermal soils of Yellowstone National Park and Lassen Volcanic National Park have found evidence of symbiosis between fungi and plants that may hold clues to how plants adapt to and tolerate extreme environments.
The research was funded in part through the National Science Foundation's (NSF) Microbial Observatories Program and published in the Nov. 22 issue of the journal Science.
Biologists Regina Redman of the University of Washington and Joan Henson of Montana State University and their colleagues examined 200 samples of Dichanthelium lanuginosum, also called "Geyser's Dichanthelium," for fungal colonization. They found what may be a new species of the fungus Curvularia that survives only in temperatures greater than 98 degrees when it associates with plants.
The researchers suggest that thermotolerance may occur through symbiotic mechanisms like heat dissipation by pigment, such as melanin, or the activation of a "biological trigger" that tells the plant to react to temperature changes more rapidly or strongly than plants that lack the fungus.
The researchers grew sample plants with and without the symbiotic fungus in a laboratory and heated the soil to test thermal resistance. The plants without the fungus shriveled at 122 degrees, whereas those plants with the fungus tolerated the heat for three days. The plants were also subjected to intermittent temperatures as high as 149 degrees. The fungus-free plants died, but the fungus-bearing plants survived for 10 days.
The researchers also demonstrated that the plants provide thermal protection to the fungus by isolating it in plant roots that had a field soil temperature of 113 degrees.
"Scientific understanding of how life can thrive in such extreme environments is at its infancy," said Microbiologist Matt Kane, NSF's Microbial Observatories Program Director. "Research funded by NSF's Microbial Observatories Program is demonstrating that when you look in interesting places, you discovery interesting life forms and interrelationships, such as these fungi and their plant partners."
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Adapted from materials provided by National Science Foundation.
ScienceDaily (Nov. 27, 2002) — ARLINGTON, Va. -- Researchers examining plants growing in the geothermal soils of Yellowstone National Park and Lassen Volcanic National Park have found evidence of symbiosis between fungi and plants that may hold clues to how plants adapt to and tolerate extreme environments.
The research was funded in part through the National Science Foundation's (NSF) Microbial Observatories Program and published in the Nov. 22 issue of the journal Science.
Biologists Regina Redman of the University of Washington and Joan Henson of Montana State University and their colleagues examined 200 samples of Dichanthelium lanuginosum, also called "Geyser's Dichanthelium," for fungal colonization. They found what may be a new species of the fungus Curvularia that survives only in temperatures greater than 98 degrees when it associates with plants.
The researchers suggest that thermotolerance may occur through symbiotic mechanisms like heat dissipation by pigment, such as melanin, or the activation of a "biological trigger" that tells the plant to react to temperature changes more rapidly or strongly than plants that lack the fungus.
The researchers grew sample plants with and without the symbiotic fungus in a laboratory and heated the soil to test thermal resistance. The plants without the fungus shriveled at 122 degrees, whereas those plants with the fungus tolerated the heat for three days. The plants were also subjected to intermittent temperatures as high as 149 degrees. The fungus-free plants died, but the fungus-bearing plants survived for 10 days.
The researchers also demonstrated that the plants provide thermal protection to the fungus by isolating it in plant roots that had a field soil temperature of 113 degrees.
"Scientific understanding of how life can thrive in such extreme environments is at its infancy," said Microbiologist Matt Kane, NSF's Microbial Observatories Program Director. "Research funded by NSF's Microbial Observatories Program is demonstrating that when you look in interesting places, you discovery interesting life forms and interrelationships, such as these fungi and their plant partners."
--------------------------------------------------------------------------------
Adapted from materials provided by National Science Foundation.
Enzyme Revealed That Is Key To Fungus's Ability To Breach Immune System
Enzyme Revealed That Is Key To Fungus's Ability To Breach Immune System
ScienceDaily (Nov. 13, 2003) — DURHAM, N.C. – A newly discovered mechanism by which an infectious fungus evades the immune system could lead to novel methods to fight the fungus and other disease-causing microbes, according to Howard Hughes Medical Institute investigators at Duke University Medical Center.
Disruption of a key enzyme in the fungus Cryptococcus neoformans – a common cause of infection of the central nervous system in patients such as organ transplant recipients who lack a functioning immune system -- led to a significant loss of fungal virulence in mice, the team found. That loss of virulence stemmed from the fungus's inability to launch a counterattack against components of the innate immune system, the body's first line of defense against infection, the study showed.
The Duke-based team -- led by HHMI geneticist Joseph Heitman, M.D., director of Duke's Center for Microbial Pathogenesis, and HHMI biochemist Jonathan Stamler, M.D. -- reported their findings in the Nov. 11, 2003, issue of Current Biology. The work was funded by the National Institutes of Allergy and Infectious Diseases and the Burroughs Wellcome Fund.
The "fungal defense" enzyme, called flavohemoglobin, is prevalent among many bacterial and fungal pathogens, Heitman said, which suggests that the findings in Cryptococcus are likely relevant to other infectious microbes. New drugs that target these enzymes might therefore represent effective treatments for a wide range of infectious diseases, he said.
The human immune system uses a two-pronged mechanism to fight infection: a rapid innate response and a slower adaptive response that depends on the production of antibodies. Key components of the innate immune system are "search-and-destroy" cells called macrophages that engulf and kill invading pathogens. Macrophages kill infectious microbes using a combination of oxidants, including hydrogen peroxide, nitric oxide and related molecules.
"The body must rely on macrophages of the innate immune system to protect itself before the adaptive immune system can respond to invasion," Heitman said. "While much is known about how pathogens defend themselves against hydrogen peroxide produced by the macrophages, this study is the first biologically relevant test of what microbes do to counteract nitric oxide and promote infection."
The researchers found that a mutant C. neoformans strain lacking the flavohemoglobin enzyme failed to break down nitric oxide in laboratory cultures. Fungus with the enzyme deficiency also ceased to grow when in the presence of nitric oxide, whereas ordinary fungus survived normally.
Mice infected with the flavohemoglobin-deficient C. neoformans survived for five days longer than those infected with the normally virulent strain. In contrast, the normal and mutant fungal strains were equally virulent in mice whose immune cells could not produce nitric oxide, the team reported.
The mutant fungus also failed to grow normally in laboratory dishes containing macrophage cells, further implicating the innate immune system in the loss of virulence exhibited by fungi lacking flavohemoglobin.
The team discovered a second enzyme, known as GSNO reductase, which also plays a role in defending the fungus against nitric oxide-related molecules produced by macrophages. Mutant fungal strains deficient in both enzymes were more severely impaired than those lacking flavohemoglobin only.
"By disabling either the fungal nitric oxide defense system or the immune system's ability to produce nitric oxide, we were able to tip the balance one way or the other – in favor of the fungal infection or the host," Heitman said. "That raises the possibility that we could treat infectious disease with drugs that either inhibit fungal defense enzymes or increase the innate immune system's ability to mount a nitrosative attack."
Collaborators on the study include Marisol de Jesus-Berrios, Ph.D., Gary Cox, M.D., Limin Liu, Ph.D., and Jesse Nussbaum, all of Duke.
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Adapted from materials provided by Duke University Medical Center.
ScienceDaily (Nov. 13, 2003) — DURHAM, N.C. – A newly discovered mechanism by which an infectious fungus evades the immune system could lead to novel methods to fight the fungus and other disease-causing microbes, according to Howard Hughes Medical Institute investigators at Duke University Medical Center.
Disruption of a key enzyme in the fungus Cryptococcus neoformans – a common cause of infection of the central nervous system in patients such as organ transplant recipients who lack a functioning immune system -- led to a significant loss of fungal virulence in mice, the team found. That loss of virulence stemmed from the fungus's inability to launch a counterattack against components of the innate immune system, the body's first line of defense against infection, the study showed.
The Duke-based team -- led by HHMI geneticist Joseph Heitman, M.D., director of Duke's Center for Microbial Pathogenesis, and HHMI biochemist Jonathan Stamler, M.D. -- reported their findings in the Nov. 11, 2003, issue of Current Biology. The work was funded by the National Institutes of Allergy and Infectious Diseases and the Burroughs Wellcome Fund.
The "fungal defense" enzyme, called flavohemoglobin, is prevalent among many bacterial and fungal pathogens, Heitman said, which suggests that the findings in Cryptococcus are likely relevant to other infectious microbes. New drugs that target these enzymes might therefore represent effective treatments for a wide range of infectious diseases, he said.
The human immune system uses a two-pronged mechanism to fight infection: a rapid innate response and a slower adaptive response that depends on the production of antibodies. Key components of the innate immune system are "search-and-destroy" cells called macrophages that engulf and kill invading pathogens. Macrophages kill infectious microbes using a combination of oxidants, including hydrogen peroxide, nitric oxide and related molecules.
"The body must rely on macrophages of the innate immune system to protect itself before the adaptive immune system can respond to invasion," Heitman said. "While much is known about how pathogens defend themselves against hydrogen peroxide produced by the macrophages, this study is the first biologically relevant test of what microbes do to counteract nitric oxide and promote infection."
The researchers found that a mutant C. neoformans strain lacking the flavohemoglobin enzyme failed to break down nitric oxide in laboratory cultures. Fungus with the enzyme deficiency also ceased to grow when in the presence of nitric oxide, whereas ordinary fungus survived normally.
Mice infected with the flavohemoglobin-deficient C. neoformans survived for five days longer than those infected with the normally virulent strain. In contrast, the normal and mutant fungal strains were equally virulent in mice whose immune cells could not produce nitric oxide, the team reported.
The mutant fungus also failed to grow normally in laboratory dishes containing macrophage cells, further implicating the innate immune system in the loss of virulence exhibited by fungi lacking flavohemoglobin.
The team discovered a second enzyme, known as GSNO reductase, which also plays a role in defending the fungus against nitric oxide-related molecules produced by macrophages. Mutant fungal strains deficient in both enzymes were more severely impaired than those lacking flavohemoglobin only.
"By disabling either the fungal nitric oxide defense system or the immune system's ability to produce nitric oxide, we were able to tip the balance one way or the other – in favor of the fungal infection or the host," Heitman said. "That raises the possibility that we could treat infectious disease with drugs that either inhibit fungal defense enzymes or increase the innate immune system's ability to mount a nitrosative attack."
Collaborators on the study include Marisol de Jesus-Berrios, Ph.D., Gary Cox, M.D., Limin Liu, Ph.D., and Jesse Nussbaum, all of Duke.
--------------------------------------------------------------------------------
Adapted from materials provided by Duke University Medical Center.
Efficient Consumption Of Copper Allows Fungus To Infect The Brain
Efficient Consumption Of Copper Allows Fungus To Infect The Brain
ScienceDaily (Feb. 9, 2007) — Infection with the fungus Cryptococcus neoformans is a problem for individuals whose immune system is compromised (for example individuals with HIV and individuals who are taking chemotherapeutics to treat cancer). It can cause either cryptococcal pneumonia or, more seriously, meningoencephalitis.
In a study that appears online on February 8 in advance of publication in the March print issue of the Journal of Clinical Investigation, researchers from the University of Illinois at Chicago show that in mice, the infecting fungus must be adapted to grow in the presence of low levels of copper if it is to efficiently infect the brain and cause meningoencephalitis.
Peter Williamson and colleagues showed that C. neoformans lacking a protein that is essential for it to take up copper from its environment (Cuf1) are impaired in their ability to infect the brain and cause fatal meningoencephalitis.
By contrast, these mutant C. neoformans infect the lung as efficiently as C. neoformans expressing Cuf1. Consistent with this, bacteria expressing high levels of a protein controlled by Cuf1 (Ctr4) were found in the brain of mice and humans infected with C. neoformans.
This study indicates that one factor that can limit the growth of C. neoformans in the brain of mice and humans is low levels of copper, but that this is not a factor limiting growth in the lung. The authors therefore suggest that determining the level of Ctr4 expressed by the C. neoformans infecting an individual might help determine that individual’s risk of developing meningoencephalitis.
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Adapted from materials provided by Journal of Clinical Investigation, via EurekAlert!, a service of AAAS.
ScienceDaily (Feb. 9, 2007) — Infection with the fungus Cryptococcus neoformans is a problem for individuals whose immune system is compromised (for example individuals with HIV and individuals who are taking chemotherapeutics to treat cancer). It can cause either cryptococcal pneumonia or, more seriously, meningoencephalitis.
In a study that appears online on February 8 in advance of publication in the March print issue of the Journal of Clinical Investigation, researchers from the University of Illinois at Chicago show that in mice, the infecting fungus must be adapted to grow in the presence of low levels of copper if it is to efficiently infect the brain and cause meningoencephalitis.
Peter Williamson and colleagues showed that C. neoformans lacking a protein that is essential for it to take up copper from its environment (Cuf1) are impaired in their ability to infect the brain and cause fatal meningoencephalitis.
By contrast, these mutant C. neoformans infect the lung as efficiently as C. neoformans expressing Cuf1. Consistent with this, bacteria expressing high levels of a protein controlled by Cuf1 (Ctr4) were found in the brain of mice and humans infected with C. neoformans.
This study indicates that one factor that can limit the growth of C. neoformans in the brain of mice and humans is low levels of copper, but that this is not a factor limiting growth in the lung. The authors therefore suggest that determining the level of Ctr4 expressed by the C. neoformans infecting an individual might help determine that individual’s risk of developing meningoencephalitis.
--------------------------------------------------------------------------------
Adapted from materials provided by Journal of Clinical Investigation, via EurekAlert!, a service of AAAS.
Taking The Fungal Route Through The Soil
Taking The Fungal Route Through The Soil
ScienceDaily (Feb. 21, 2007) — Fungal hyphae play a greater role in the spread of bacteria in the soil than was previously suspected. This is the finding reported by scientists from the Helmholtz Centre for Environmental Research (UFZ) in the scientific journal Environmental Science & Technology. For the first time, scientists have been able to prove that bacteria are able to travel through the soil on the mucous membrane of living fungi.
The experiments could help speed up the remediation of contaminated land using bacteria that break down harmful substances. Air and a lack of moisture create a barrier to the mobility of bacteria in the soil, preventing them from spreading and delaying the breakdown of pollutants.
Everything is just a question of contacts
It looks like a giant green ball of wool. With a bit of imagination the photo could also be likened to a huge motorway interchange with countless roads and junctions passing over and under each other on different levels. But what Leipzig-based microbiologist Dr Lukas Y. Wick is observing so intently on his screen is in fact a photograph of a mycelium taken with a confocal laser scanning microscope. The thread-like hyphae have a diameter of just 10 micrometres – one-seventh of the diameter of a human hair.
Nevertheless, fungi are some of the world’s greatest biomass producers. A single gram of field soil can contain up to 100 metres of mycelium. Wick’s actual research objects are much smaller still. He is interested in soil bacteria. Bacteria can weaken the human organism, but they can also be useful, e.g. by breaking down pollutants.
“For the bacterium a harmful substance is not harmful,” explains Wick. “It simply breaks down the carbon compounds, producing the energy and substances that it needs to live.” But before it can do this it has to get at its ‘food’. Air and lack of moisture present insurmountable obstacles. “This is why certain pollutants are broken down so slowly in the soil. Often it is not a lack of biochemical capacity, but rather a lack of contacts.” The scientists at the UFZ are therefore studying the paths followed by the bacteria.
Probably the world’s largest motorway network
Mycelia appear to act as a kind of underground highway for bacteria. This is the conclusion reached by Lukas Wick and his team. In the laboratory experiment they succeeded in demonstrating that the bacteria move through the soil on the mycelium. The ingredients: one pollutant, separating layers made of glass pellets, uncontaminated soil and a bacterium called Pseudomonas putida. The bacteria have to fight their way through all these layers to reach the phenanthrene, their ‘food’. This polycyclic aromatic hydrocarbon is a widespread pollutant produced during every combustion process: at petrol stations, in car exhausts, during forest fires, in cigarette smoke and in old municipal gas works.
“We deliberately make the bacteria work their way upwards against gravity so that people can’t say there could be a small amount of water trickling down and carrying the bacteria with it,” says Wick. “We have tried to rule out any doubts and objections from potential critics.” The bacteria made it to the top only in places where there was a mycelium running through the soil. In the identical parallel experiment without a mycelium the bacteria were unable to surmount the barriers. “With this paper we have shown that there is an infrastructure.”
Just follow your nose
The bacteria in this laboratory experiment are so-called chemotactic bacteria. This means that they measure the concentration of their ‘target chemical’ and then move towards where the concentration is higher – as if on autopilot.
“A bacterium is not a stupid creature – it has adapted to its environment and goes where there is food.” Only one type of bacteria was used in the model experiment. In nature, however, there are countless different bacteria, which gives rise to new questions: for which of them is it an advantage to be mobile and for which is it not? It will, therefore, be some time before the processes in the soil are fully understood.
The future aim of the Helmholtz researchers is to model microbial landscapes and to investigate what happens under the influence of different factors. For this they will make use of a tool that has already helped to predict the spread of rabies and the spread of resettled animal species – ecological modelling, which in future will also be able to provide forecasts about the spread of bacteria. This knowledge will make it easier to remediate contaminated soil, perhaps making the ‘fungal highway’ not only the largest in the world, but also the only one to help return nature to its original state.
--------------------------------------------------------------------------------
Adapted from materials provided by Helmholtz Centre For Environmental Research - UFZ.
ScienceDaily (Feb. 21, 2007) — Fungal hyphae play a greater role in the spread of bacteria in the soil than was previously suspected. This is the finding reported by scientists from the Helmholtz Centre for Environmental Research (UFZ) in the scientific journal Environmental Science & Technology. For the first time, scientists have been able to prove that bacteria are able to travel through the soil on the mucous membrane of living fungi.
The experiments could help speed up the remediation of contaminated land using bacteria that break down harmful substances. Air and a lack of moisture create a barrier to the mobility of bacteria in the soil, preventing them from spreading and delaying the breakdown of pollutants.
Everything is just a question of contacts
It looks like a giant green ball of wool. With a bit of imagination the photo could also be likened to a huge motorway interchange with countless roads and junctions passing over and under each other on different levels. But what Leipzig-based microbiologist Dr Lukas Y. Wick is observing so intently on his screen is in fact a photograph of a mycelium taken with a confocal laser scanning microscope. The thread-like hyphae have a diameter of just 10 micrometres – one-seventh of the diameter of a human hair.
Nevertheless, fungi are some of the world’s greatest biomass producers. A single gram of field soil can contain up to 100 metres of mycelium. Wick’s actual research objects are much smaller still. He is interested in soil bacteria. Bacteria can weaken the human organism, but they can also be useful, e.g. by breaking down pollutants.
“For the bacterium a harmful substance is not harmful,” explains Wick. “It simply breaks down the carbon compounds, producing the energy and substances that it needs to live.” But before it can do this it has to get at its ‘food’. Air and lack of moisture present insurmountable obstacles. “This is why certain pollutants are broken down so slowly in the soil. Often it is not a lack of biochemical capacity, but rather a lack of contacts.” The scientists at the UFZ are therefore studying the paths followed by the bacteria.
Probably the world’s largest motorway network
Mycelia appear to act as a kind of underground highway for bacteria. This is the conclusion reached by Lukas Wick and his team. In the laboratory experiment they succeeded in demonstrating that the bacteria move through the soil on the mycelium. The ingredients: one pollutant, separating layers made of glass pellets, uncontaminated soil and a bacterium called Pseudomonas putida. The bacteria have to fight their way through all these layers to reach the phenanthrene, their ‘food’. This polycyclic aromatic hydrocarbon is a widespread pollutant produced during every combustion process: at petrol stations, in car exhausts, during forest fires, in cigarette smoke and in old municipal gas works.
“We deliberately make the bacteria work their way upwards against gravity so that people can’t say there could be a small amount of water trickling down and carrying the bacteria with it,” says Wick. “We have tried to rule out any doubts and objections from potential critics.” The bacteria made it to the top only in places where there was a mycelium running through the soil. In the identical parallel experiment without a mycelium the bacteria were unable to surmount the barriers. “With this paper we have shown that there is an infrastructure.”
Just follow your nose
The bacteria in this laboratory experiment are so-called chemotactic bacteria. This means that they measure the concentration of their ‘target chemical’ and then move towards where the concentration is higher – as if on autopilot.
“A bacterium is not a stupid creature – it has adapted to its environment and goes where there is food.” Only one type of bacteria was used in the model experiment. In nature, however, there are countless different bacteria, which gives rise to new questions: for which of them is it an advantage to be mobile and for which is it not? It will, therefore, be some time before the processes in the soil are fully understood.
The future aim of the Helmholtz researchers is to model microbial landscapes and to investigate what happens under the influence of different factors. For this they will make use of a tool that has already helped to predict the spread of rabies and the spread of resettled animal species – ecological modelling, which in future will also be able to provide forecasts about the spread of bacteria. This knowledge will make it easier to remediate contaminated soil, perhaps making the ‘fungal highway’ not only the largest in the world, but also the only one to help return nature to its original state.
--------------------------------------------------------------------------------
Adapted from materials provided by Helmholtz Centre For Environmental Research - UFZ.
Mutualism: Fungus Found That Needs Bacteria In Cytoplasm To Reproduce
Mutualism: Fungus Found That Needs Bacteria In Cytoplasm To Reproduce
ScienceDaily (Apr. 6, 2007) — Endosymbiotic relationships--in which one organism lives within another--are striking examples of mutualism, and can often significantly shape the biology of the participant species.
In new findings that highlight the extent to which a host organism can become dependent on its internal symbiont, researchers have identified a case in which the reproduction of a fungus has become dependent on bacteria that live within its cytoplasm. The findings, which appear online in the journal Current Biology on April 5th, are reported by Laila Partida and Christian Hertweck from the Leibniz Institute for Natural Product Research and Infection Biology in Jena, Germany.
The particular partnership under study is the symbiosis of the fungus Rhizopus microsporus and Burkholderia bacteria that live within its cells. The two species effectively team up to break down young rice plants for their nutrients, causing a plant disease known as rice seedling blight. Past work from the research group had revealed that the Burkholderia bacteria play a critical role in the virulence of the fungus against rice seedlings: The bacteria produce a plant poison known as rhizoxin, which has been shown to be the causative agent in rice seedling blight.
The researchers now report a second, striking benefit conferred on the fungus by its intracellular symbiont. When the bacteria are eliminated from the fungus with antibiotic treatment, the fungal cells are no longer able to form spores, suggesting that the bacterial symbiont is in fact required for this mode of fungal reproduction. Spore formation in fungi is a universal process that allows the rapid distribution of fungal cells. The new findings appear to represent the first known case in which spore formation--also known as vegetative reproduction--depends on the presence of another organism.
The researchers found that when both organisms were brought together to re-establish the symbiosis, sporulation was restored in the fungus.
In collaboration with researchers at the Leibniz Institute for Age Research, Jena, the team also made progress in understanding how the endosymbiotic bacteria influence reproduction by their host. Using a laser gun to introduce Burkholderia that had been specially labeled with a marker known as green fluorescent protein, the researchers were able to detect the bacteria within both mycelium--the vegetative portion of the fungus--and fungal spores.
On the basis of their findings, the authors conclude that the symbiont-dependent spore formation they observe is a means to maintain the symbiosis between the two species. Although the fungus has lost control over its reproduction, the endofungal bacteria in return provide a highly potent toxin for defending the habitat and accessing nutrients from decaying plants.
Partida-Martinez et al.: "Endosymbiont-Dependent Host Reproduction Maintains Bacterial-Fungal Mutualism." Publishing in Current Biology 17, 1--5, May 1, 2007. DOI 10.1016/j.cub.2007.03.039.
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Adapted from materials provided by Cell Press, via EurekAlert!, a service of AAAS.
ScienceDaily (Apr. 6, 2007) — Endosymbiotic relationships--in which one organism lives within another--are striking examples of mutualism, and can often significantly shape the biology of the participant species.
In new findings that highlight the extent to which a host organism can become dependent on its internal symbiont, researchers have identified a case in which the reproduction of a fungus has become dependent on bacteria that live within its cytoplasm. The findings, which appear online in the journal Current Biology on April 5th, are reported by Laila Partida and Christian Hertweck from the Leibniz Institute for Natural Product Research and Infection Biology in Jena, Germany.
The particular partnership under study is the symbiosis of the fungus Rhizopus microsporus and Burkholderia bacteria that live within its cells. The two species effectively team up to break down young rice plants for their nutrients, causing a plant disease known as rice seedling blight. Past work from the research group had revealed that the Burkholderia bacteria play a critical role in the virulence of the fungus against rice seedlings: The bacteria produce a plant poison known as rhizoxin, which has been shown to be the causative agent in rice seedling blight.
The researchers now report a second, striking benefit conferred on the fungus by its intracellular symbiont. When the bacteria are eliminated from the fungus with antibiotic treatment, the fungal cells are no longer able to form spores, suggesting that the bacterial symbiont is in fact required for this mode of fungal reproduction. Spore formation in fungi is a universal process that allows the rapid distribution of fungal cells. The new findings appear to represent the first known case in which spore formation--also known as vegetative reproduction--depends on the presence of another organism.
The researchers found that when both organisms were brought together to re-establish the symbiosis, sporulation was restored in the fungus.
In collaboration with researchers at the Leibniz Institute for Age Research, Jena, the team also made progress in understanding how the endosymbiotic bacteria influence reproduction by their host. Using a laser gun to introduce Burkholderia that had been specially labeled with a marker known as green fluorescent protein, the researchers were able to detect the bacteria within both mycelium--the vegetative portion of the fungus--and fungal spores.
On the basis of their findings, the authors conclude that the symbiont-dependent spore formation they observe is a means to maintain the symbiosis between the two species. Although the fungus has lost control over its reproduction, the endofungal bacteria in return provide a highly potent toxin for defending the habitat and accessing nutrients from decaying plants.
Partida-Martinez et al.: "Endosymbiont-Dependent Host Reproduction Maintains Bacterial-Fungal Mutualism." Publishing in Current Biology 17, 1--5, May 1, 2007. DOI 10.1016/j.cub.2007.03.039.
--------------------------------------------------------------------------------
Adapted from materials provided by Cell Press, via EurekAlert!, a service of AAAS.
Fungi Respond To Climate Change
ScienceDaily (Apr. 25, 2007) — Climate change is dramatically altering the growing patterns of mushrooms, toadstools and other fungi, new research has found.
There are around 18,000 different species of fungi in the UK -- three times as many as all plants put together. They provide vital ecosystem services for the welfare of native trees and other plants, and are the natural recyclers of the planet, but until now their response to global climate change has not been examined.
A team from Cardiff University’s School of Biosciences working on a project led by Royal Holloway, University of London and with the Natural Environment Research Council Centre for Ecology and Hydrology studied more than 52,000 fungal fruiting records from nearly 1,400 localities collected in southern England between 1950 - 2005.
The study found that fungi are fruiting significantly earlier and for a longer period than ever before. In the 1950s fungi fruited over a period of around 33 days but this has more than doubled to nearly 75 days in the current decade.
Professor Lynne Boddy, Cardiff School of Biosciences said: "The increase in the overall fruiting period is dramatic, and much higher than equivalent spring data reported for plants, insects or birds."
The study found that the alteration in fungal fruiting mirrors changes in British temperatures that have occurred since 1975. The increase in late summer temperatures and autumnal rains has caused early season species to fruit earlier and late season species to continue to fruit later. Furthermore, climate warming seems to have caused significant numbers of species to begin fruiting in spring as well as autumn, suggesting increases in decay rates in forests.
--------------------------------------------------------------------------------
Adapted from materials provided by Cardiff University.
ScienceDaily (Apr. 25, 2007) — Climate change is dramatically altering the growing patterns of mushrooms, toadstools and other fungi, new research has found.
There are around 18,000 different species of fungi in the UK -- three times as many as all plants put together. They provide vital ecosystem services for the welfare of native trees and other plants, and are the natural recyclers of the planet, but until now their response to global climate change has not been examined.
A team from Cardiff University’s School of Biosciences working on a project led by Royal Holloway, University of London and with the Natural Environment Research Council Centre for Ecology and Hydrology studied more than 52,000 fungal fruiting records from nearly 1,400 localities collected in southern England between 1950 - 2005.
The study found that fungi are fruiting significantly earlier and for a longer period than ever before. In the 1950s fungi fruited over a period of around 33 days but this has more than doubled to nearly 75 days in the current decade.
Professor Lynne Boddy, Cardiff School of Biosciences said: "The increase in the overall fruiting period is dramatic, and much higher than equivalent spring data reported for plants, insects or birds."
The study found that the alteration in fungal fruiting mirrors changes in British temperatures that have occurred since 1975. The increase in late summer temperatures and autumnal rains has caused early season species to fruit earlier and late season species to continue to fruit later. Furthermore, climate warming seems to have caused significant numbers of species to begin fruiting in spring as well as autumn, suggesting increases in decay rates in forests.
--------------------------------------------------------------------------------
Adapted from materials provided by Cardiff University.
Secrets Of Cooperation Between Trees And Fungi Revealed
Secrets Of Cooperation Between Trees And Fungi Revealed
ScienceDaily (Mar. 6, 2008) — Plants gained their ancestral toehold on dry land with considerable help from their fungal friends. Now, millennia later, that partnership is being exploited as a strategy to bolster biomass production for next generation biofuels. The genetic mechanism of this kind of symbiosis, which contributes to the delicate ecological balance in healthy forests, also provides insights into plant health that may enable more efficient carbon sequestration and enhanced phytoremediation, using plants to clean up environmental contaminants.
These prospects stem from the genome analysis of the symbiotic fungus Laccaria bicolor, generated by the U.S. Department of Energy Joint Genome Institute (DOE JGI) and collaborators from INRA, the National Institute for Agricultural Research in Nancy, France, and published March 6 in the journal Nature. This international team effort also involved contributions from 16 institutions, including Oak Ridge National Laboratory; Ghent University, Belgium; Lund University, Sweden; Goettingen University, Germany; CNRS-Aix-Marseille University, France; Nancy University, France; and the University of Alabama, Huntsville.
In a manner of speaking, trees are the lungs of the earth. They draw CO2 from the atmosphere and convert it into sugars, which then become a source of energy. In the process they breathe O2 back into the atmosphere. This "green" production of biomass -- trees account for 90% of the planet's land-based biomass -- is a major influence on the health of our planet.
Trees' ability to generate large amounts of biomass or store carbon is underpinned by their interactions with soil microbes known as mycorrhizal fungi, which excel at procuring necessary, but scarce, nutrients such as phosphate and nitrogen. Most of these nutrients are transferred to the growing tree. When Laccaria bicolor establishes a partnership with plant roots, a mycorrhizal root is created. The fungus within the root is protected from competition with other soil microbes and gains preferential access to carbohydrates within the plant. Thus, the mutualistic relationship is established.
"Forests around the world rely on the partnership between plant roots and soil fungi and the environment they create, the rhizosphere," said Eddy Rubin, DOE JGI Director. "The Laccaria genome represents a valuable resource, the first of a series of tree community genomics projects to have passed through our production sequencing line. These community resources promise to advance a systems approach to forest genomics."
Rubin indicates that by using DNA sequence to survey the forest ecosystem, from the plants to symbiotic and pathogenic fungi, researchers can ultimately optimize the conditions under which a biomass plantation would thrive. "We now have the opportunity to gain fundamental insights into plant development and growth as related to their intimate interaction which symbiotic fungi. These insights will lead to bolstered biomass productivity and improved forests."
Laccaria bicolor occurs frequently in the birch, fir, and pine forests of North America and is a common symbiont of Populus, the poplar tree whose genome was determined by the JGI in 2006 The analysis of the 65-million-base Laccaria genome, the largest fungal genome sequenced to date, yielded 20,000 predicted protein-encoding genes, almost as many as in the human genome. In sifting through these data, researchers have discovered many unexpected features, including an arsenal of small secreted proteins (SSPs), several of which are only expressed in tissues associated with symbiosis. The most prominent SSP accumulates in the extending hyphae, the tips of the fungus that colonize the roots of the host plant.
"We believe that the proteins specific to this host/fungus interface play a decisive role in the establishment of symbiosis," said Francis Martin, the Nature study's lead author. This genome exploration led Martin and his CNRS-Marseille University and DOE JGI colleagues to the unexpected observation that the genome of Laccaria lacks the enzymes involved in degradation of the carbohydrate polymers of plant cell walls but maintains the ability to degrade non-plant cell walls, which may account for Laccaria's protective capacity. These observations point towards the dual life that mycorrhizal fungi like Laccaria possess, that is, the ability to grow in soil fending off pathogens and using decaying organic matter while serving as a custodian of living plant roots.
The genome, Martin said, shows a large number of new and expanded gene families compared with other fungi. Many of these families are involved in signaling and other processes that drive the complex transition between two distinct lifestyles of Laccaria: the benign saprotroph, able to use decaying matter of animal and bacterial origins, versus the symbiont, living in mutually profitable harmony with plant roots.
The team also discovered new classes of genes that may be candidates for the complex communication that must occur between the players in the host/plant subsoil arena during fungal development. They report that fungi play a critical role in plant nutrient use efficiency by translocating nutrients and water captured in soil pores inaccessible to roots of the host plant.
"The Laccaria genome sequence, its analysis, associated genomics, and bioinformatics tools provide an unprecedented opportunity to identify the key components of organism-environment interactions that modulate ecosystem responses to global change and increased nutrient input needed for faster growth, said Martin. "By examining and manipulating patterns of gene expression, we can identify the genetic control points that regulate plant growth and plant-mutualist response in an effort to better understand how these interactions control ecosystem function."
Mycorrhizae are critical elements of the terrestrial ecosystems, Martin said, since approximately 85 percent of all plant species, including trees, are dependent on such interactions to thrive. Mycorrhizae significantly improve photosynthetic carbon assimilation by plants.
"Host trees like Populus are able to harness this formidable web of mycorrhizal hyphae that permeates the soil and leaf litter and coax a relationship for their mutual nutritional benefit," said co-author DOE JGI and Oak Ridge National Laboratory researcher Jerry Tuskan. "This process is absolutely critical to the success of the interactions between the fungi and the roots of the host plant so that an equitable exchange of nutrients can be achieved." The DOE JGI and its collaborators have now embarked on characterizing several other poplar community symbionts that will provide a more comprehensive understanding of the biological community of the poplar forest. These include Glomus, a second plant symbiotic fungus, Melampsora, a leaf pathogen, and several plant endophytes, bacteria and fungi that live inside the poplar tree.
"DOE JGI's expanding portfolio of community genomes provides the researchers with a set of resources that can be used to map out the processes by which fungi colonize wood and soil litter. These fungi interact with living plants within their ecosystem in order to perform vital functions in the carbon and nitrogen cycles that are so fundamental to sustainable plant growth," said Tuskan.
The DOE JGI Laccaria effort was led by Igor Grigoriev. Other authors include Andrea Aerts, Erika Lindquist, Asaf Salamov, Harris Shapiro, Peter Brokstein, Chris Detter (Los Alamos National Laboratory), the DOE JGI Production Genomics Facility sequencing team led by Susan Lucas, and partners at the Stanford Human Genome Center, Jane Grimwood and Jeremy Schmutz.
--------------------------------------------------------------------------------
Adapted from materials provided by DOE/Joint Genome Institute.
ScienceDaily (Mar. 6, 2008) — Plants gained their ancestral toehold on dry land with considerable help from their fungal friends. Now, millennia later, that partnership is being exploited as a strategy to bolster biomass production for next generation biofuels. The genetic mechanism of this kind of symbiosis, which contributes to the delicate ecological balance in healthy forests, also provides insights into plant health that may enable more efficient carbon sequestration and enhanced phytoremediation, using plants to clean up environmental contaminants.
These prospects stem from the genome analysis of the symbiotic fungus Laccaria bicolor, generated by the U.S. Department of Energy Joint Genome Institute (DOE JGI) and collaborators from INRA, the National Institute for Agricultural Research in Nancy, France, and published March 6 in the journal Nature. This international team effort also involved contributions from 16 institutions, including Oak Ridge National Laboratory; Ghent University, Belgium; Lund University, Sweden; Goettingen University, Germany; CNRS-Aix-Marseille University, France; Nancy University, France; and the University of Alabama, Huntsville.
In a manner of speaking, trees are the lungs of the earth. They draw CO2 from the atmosphere and convert it into sugars, which then become a source of energy. In the process they breathe O2 back into the atmosphere. This "green" production of biomass -- trees account for 90% of the planet's land-based biomass -- is a major influence on the health of our planet.
Trees' ability to generate large amounts of biomass or store carbon is underpinned by their interactions with soil microbes known as mycorrhizal fungi, which excel at procuring necessary, but scarce, nutrients such as phosphate and nitrogen. Most of these nutrients are transferred to the growing tree. When Laccaria bicolor establishes a partnership with plant roots, a mycorrhizal root is created. The fungus within the root is protected from competition with other soil microbes and gains preferential access to carbohydrates within the plant. Thus, the mutualistic relationship is established.
"Forests around the world rely on the partnership between plant roots and soil fungi and the environment they create, the rhizosphere," said Eddy Rubin, DOE JGI Director. "The Laccaria genome represents a valuable resource, the first of a series of tree community genomics projects to have passed through our production sequencing line. These community resources promise to advance a systems approach to forest genomics."
Rubin indicates that by using DNA sequence to survey the forest ecosystem, from the plants to symbiotic and pathogenic fungi, researchers can ultimately optimize the conditions under which a biomass plantation would thrive. "We now have the opportunity to gain fundamental insights into plant development and growth as related to their intimate interaction which symbiotic fungi. These insights will lead to bolstered biomass productivity and improved forests."
Laccaria bicolor occurs frequently in the birch, fir, and pine forests of North America and is a common symbiont of Populus, the poplar tree whose genome was determined by the JGI in 2006 The analysis of the 65-million-base Laccaria genome, the largest fungal genome sequenced to date, yielded 20,000 predicted protein-encoding genes, almost as many as in the human genome. In sifting through these data, researchers have discovered many unexpected features, including an arsenal of small secreted proteins (SSPs), several of which are only expressed in tissues associated with symbiosis. The most prominent SSP accumulates in the extending hyphae, the tips of the fungus that colonize the roots of the host plant.
"We believe that the proteins specific to this host/fungus interface play a decisive role in the establishment of symbiosis," said Francis Martin, the Nature study's lead author. This genome exploration led Martin and his CNRS-Marseille University and DOE JGI colleagues to the unexpected observation that the genome of Laccaria lacks the enzymes involved in degradation of the carbohydrate polymers of plant cell walls but maintains the ability to degrade non-plant cell walls, which may account for Laccaria's protective capacity. These observations point towards the dual life that mycorrhizal fungi like Laccaria possess, that is, the ability to grow in soil fending off pathogens and using decaying organic matter while serving as a custodian of living plant roots.
The genome, Martin said, shows a large number of new and expanded gene families compared with other fungi. Many of these families are involved in signaling and other processes that drive the complex transition between two distinct lifestyles of Laccaria: the benign saprotroph, able to use decaying matter of animal and bacterial origins, versus the symbiont, living in mutually profitable harmony with plant roots.
The team also discovered new classes of genes that may be candidates for the complex communication that must occur between the players in the host/plant subsoil arena during fungal development. They report that fungi play a critical role in plant nutrient use efficiency by translocating nutrients and water captured in soil pores inaccessible to roots of the host plant.
"The Laccaria genome sequence, its analysis, associated genomics, and bioinformatics tools provide an unprecedented opportunity to identify the key components of organism-environment interactions that modulate ecosystem responses to global change and increased nutrient input needed for faster growth, said Martin. "By examining and manipulating patterns of gene expression, we can identify the genetic control points that regulate plant growth and plant-mutualist response in an effort to better understand how these interactions control ecosystem function."
Mycorrhizae are critical elements of the terrestrial ecosystems, Martin said, since approximately 85 percent of all plant species, including trees, are dependent on such interactions to thrive. Mycorrhizae significantly improve photosynthetic carbon assimilation by plants.
"Host trees like Populus are able to harness this formidable web of mycorrhizal hyphae that permeates the soil and leaf litter and coax a relationship for their mutual nutritional benefit," said co-author DOE JGI and Oak Ridge National Laboratory researcher Jerry Tuskan. "This process is absolutely critical to the success of the interactions between the fungi and the roots of the host plant so that an equitable exchange of nutrients can be achieved." The DOE JGI and its collaborators have now embarked on characterizing several other poplar community symbionts that will provide a more comprehensive understanding of the biological community of the poplar forest. These include Glomus, a second plant symbiotic fungus, Melampsora, a leaf pathogen, and several plant endophytes, bacteria and fungi that live inside the poplar tree.
"DOE JGI's expanding portfolio of community genomes provides the researchers with a set of resources that can be used to map out the processes by which fungi colonize wood and soil litter. These fungi interact with living plants within their ecosystem in order to perform vital functions in the carbon and nitrogen cycles that are so fundamental to sustainable plant growth," said Tuskan.
The DOE JGI Laccaria effort was led by Igor Grigoriev. Other authors include Andrea Aerts, Erika Lindquist, Asaf Salamov, Harris Shapiro, Peter Brokstein, Chris Detter (Los Alamos National Laboratory), the DOE JGI Production Genomics Facility sequencing team led by Susan Lucas, and partners at the Stanford Human Genome Center, Jane Grimwood and Jeremy Schmutz.
--------------------------------------------------------------------------------
Adapted from materials provided by DOE/Joint Genome Institute.
Self-fertility In Fungi: The Secrets Of 'DIY Reproduction'
Self-fertility In Fungi: The Secrets Of 'DIY Reproduction'
ScienceDaily (Aug. 17, 2007) — Research from The University of Nottingham sheds new light on a fascinating phenomenon of the natural world — the ability of some species to reproduce sexually without a partner.
Scientists have been trying to determine how individuals of a key fungus, Aspergillus nidulans, are able to have sex without the need for a partner.
In new findings published in the journal Current Biology on August 2, they reveal that the fungus has evolved to incorporate the two different sexes into the same individual.
This means that when sex occurs the fungus activates its internal sexual machinery and in essence 'mates with itself' to produce new offspring, rather than bypassing the sexual act.
This is a significant discovery as it helps scientists to understand how fungi reproduce in general. Fungi can cause health problems in humans and other serious animal and plant diseases, but are also useful as sources of pharmaceuticals and food products.
The long-term aim of the research is to be able to manipulate fungal sex to our own advantage, to prevent disease and help produce better strains for use in the food and biotech industries.
Dr Paul Dyer, of the School of Biology, was lead author of the study. He said: “When we think of sex in the animal world we normally associate it with males and females attracting each other and then coming together for the sexual act.”
“But things are different in the fungal and plant kingdoms, where a lot of species are 'self fertile'. This means that they are able to have sex to produce spores and seeds without the need for a compatible partner. Our findings show that Aspergillus nidulans provides a true example of 'DIY sex'.”
Self-fertilisation is thought to have developed in some plant and fungal species as a response to a scarcity of compatible mating partners. It also allows species to maintain a combination of genes — called a genotype — that is well adapted to surviving in a certain environment.
Aspergillus nidulans is often used as a model organism for scientists studying a wide range of subjects including basic genetic problems that are also applicable to humans, including recombination, DNA repair and cell metabolism.
The work was supported by a grant from the Biotechnology and Biological Sciences Research Council (BBSRC) and also involved researchers at Northern Illinois University and CNRS in France.
--------------------------------------------------------------------------------
Adapted from materials provided by University of Nottingham.
ScienceDaily (Aug. 17, 2007) — Research from The University of Nottingham sheds new light on a fascinating phenomenon of the natural world — the ability of some species to reproduce sexually without a partner.
Scientists have been trying to determine how individuals of a key fungus, Aspergillus nidulans, are able to have sex without the need for a partner.
In new findings published in the journal Current Biology on August 2, they reveal that the fungus has evolved to incorporate the two different sexes into the same individual.
This means that when sex occurs the fungus activates its internal sexual machinery and in essence 'mates with itself' to produce new offspring, rather than bypassing the sexual act.
This is a significant discovery as it helps scientists to understand how fungi reproduce in general. Fungi can cause health problems in humans and other serious animal and plant diseases, but are also useful as sources of pharmaceuticals and food products.
The long-term aim of the research is to be able to manipulate fungal sex to our own advantage, to prevent disease and help produce better strains for use in the food and biotech industries.
Dr Paul Dyer, of the School of Biology, was lead author of the study. He said: “When we think of sex in the animal world we normally associate it with males and females attracting each other and then coming together for the sexual act.”
“But things are different in the fungal and plant kingdoms, where a lot of species are 'self fertile'. This means that they are able to have sex to produce spores and seeds without the need for a compatible partner. Our findings show that Aspergillus nidulans provides a true example of 'DIY sex'.”
Self-fertilisation is thought to have developed in some plant and fungal species as a response to a scarcity of compatible mating partners. It also allows species to maintain a combination of genes — called a genotype — that is well adapted to surviving in a certain environment.
Aspergillus nidulans is often used as a model organism for scientists studying a wide range of subjects including basic genetic problems that are also applicable to humans, including recombination, DNA repair and cell metabolism.
The work was supported by a grant from the Biotechnology and Biological Sciences Research Council (BBSRC) and also involved researchers at Northern Illinois University and CNRS in France.
--------------------------------------------------------------------------------
Adapted from materials provided by University of Nottingham.
Evolution Of The Sexes: What A Fungus Can Tell Us
Evolution Of The Sexes: What A Fungus Can Tell Us
ScienceDaily (Jan. 10, 2008) — Fungi don't exactly come in boy and girl varieties, but they do have sex differences. In fact, a new finding from Duke University Medical Center shows that some of the earliest evolved forms of fungus contain clues to how the sexes evolved in higher animals, including that distant cousin of fungus, the human.
A team lead by Joseph Heitman, M.D. has isolated sex-determining genes from one of the oldest known types of fungi, Phycomyces blakesleeanus, findings which appear in the Jan. 10 issue of Nature.
Fungi do not have entire sex chromosomes, like the familiar X and Y chromosomes that determine sexual identity in humans. Instead, they have sex determining sequences of DNA called "mating-type loci."
Mating-type loci have been found in a number of higher-level fungal species, and exhibit an unusual amount of diversity. These differences occur even among similar fungal species leading scientists to wonder how they evolved.
Heitman's group hypothesized that the sex-determining arrangement found in one of earliest forms of fungi might reveal the ancestral structure of mating-type loci, serving as a sort of molecular fossil.
"Fungi are good model systems for the evolution of human sexual differentiation because the genetic sequences responsible for sex are smaller versions of chromosomal sex-determining regions in people," Heitman said.
To identify the mating-type loci in Phycomyces, the researchers used a computer search to compare known mating-type loci in the genomes of other fungal lineages and then genetic mapping. "We employed a usual-suspects approach, comparing proteins between fungal types before identifying a candidate that appeared related in all lineages," says Heitman.
Within this stretch of DNA, they were able to isolate two versions of a gene that regulates mating, which they dubbed sexM, (sex minus) and sexP (sex plus). Strains of fungi with opposite versions of the sex genes are able to mate with each other.
Both versions of the gene, sexM and sexP, encode for a single protein called a high mobility group (HMG)-domain protein that leads to sex differentiation through an unknown process. This protein is very similar to one encoded by the human Y chromosome, called SRY, that when turned on leads a developing fetus to exhibit male characteristics. Heitman said this similarity suggests that HMG-domain proteins may mark the evolutionary beginnings of sex determination in both fungi and humans.
Heitman's team proposes that sexM and sexP were once the same gene that went through a mutation process called inversion. The new versions then evolved into two separate sex genes. The same process is most likely responsible for the evolution of the male Y chromosome, Heitman suggests.
Heitman hopes to next identify the sex region in another fungus, Rhizopus oryzae in order to better understand how HMG-domain proteins control sex determination in fungi. Rhizopus' genes can be cultured and chemically altered in a way that Phycomyces' sex genes can not.
"Rhizopus can be used to understand the influences of certain genes in lesser studied fungi much in the way we use mice to understand genetic effects in humans," explained Alexander Idnurm, Ph.D., the primary author on the study and recently appointed assistant professor at the University of Missouri-Kansas City.
Another troubling mystery for Heitman is that certain younger fungal species lack HMG-domain proteins. He proposes that these proteins have been replaced with alternative transcription factors, which are proteins that turn genes on and off.
--------------------------------------------------------------------------------
Adapted from materials provided by Duke University Medical Center.
ScienceDaily (Jan. 10, 2008) — Fungi don't exactly come in boy and girl varieties, but they do have sex differences. In fact, a new finding from Duke University Medical Center shows that some of the earliest evolved forms of fungus contain clues to how the sexes evolved in higher animals, including that distant cousin of fungus, the human.
A team lead by Joseph Heitman, M.D. has isolated sex-determining genes from one of the oldest known types of fungi, Phycomyces blakesleeanus, findings which appear in the Jan. 10 issue of Nature.
Fungi do not have entire sex chromosomes, like the familiar X and Y chromosomes that determine sexual identity in humans. Instead, they have sex determining sequences of DNA called "mating-type loci."
Mating-type loci have been found in a number of higher-level fungal species, and exhibit an unusual amount of diversity. These differences occur even among similar fungal species leading scientists to wonder how they evolved.
Heitman's group hypothesized that the sex-determining arrangement found in one of earliest forms of fungi might reveal the ancestral structure of mating-type loci, serving as a sort of molecular fossil.
"Fungi are good model systems for the evolution of human sexual differentiation because the genetic sequences responsible for sex are smaller versions of chromosomal sex-determining regions in people," Heitman said.
To identify the mating-type loci in Phycomyces, the researchers used a computer search to compare known mating-type loci in the genomes of other fungal lineages and then genetic mapping. "We employed a usual-suspects approach, comparing proteins between fungal types before identifying a candidate that appeared related in all lineages," says Heitman.
Within this stretch of DNA, they were able to isolate two versions of a gene that regulates mating, which they dubbed sexM, (sex minus) and sexP (sex plus). Strains of fungi with opposite versions of the sex genes are able to mate with each other.
Both versions of the gene, sexM and sexP, encode for a single protein called a high mobility group (HMG)-domain protein that leads to sex differentiation through an unknown process. This protein is very similar to one encoded by the human Y chromosome, called SRY, that when turned on leads a developing fetus to exhibit male characteristics. Heitman said this similarity suggests that HMG-domain proteins may mark the evolutionary beginnings of sex determination in both fungi and humans.
Heitman's team proposes that sexM and sexP were once the same gene that went through a mutation process called inversion. The new versions then evolved into two separate sex genes. The same process is most likely responsible for the evolution of the male Y chromosome, Heitman suggests.
Heitman hopes to next identify the sex region in another fungus, Rhizopus oryzae in order to better understand how HMG-domain proteins control sex determination in fungi. Rhizopus' genes can be cultured and chemically altered in a way that Phycomyces' sex genes can not.
"Rhizopus can be used to understand the influences of certain genes in lesser studied fungi much in the way we use mice to understand genetic effects in humans," explained Alexander Idnurm, Ph.D., the primary author on the study and recently appointed assistant professor at the University of Missouri-Kansas City.
Another troubling mystery for Heitman is that certain younger fungal species lack HMG-domain proteins. He proposes that these proteins have been replaced with alternative transcription factors, which are proteins that turn genes on and off.
--------------------------------------------------------------------------------
Adapted from materials provided by Duke University Medical Center.
Fungi Can Tell Us About The Origin Of Sex Chromosomes
Fungi Can Tell Us About The Origin Of Sex Chromosomes
ScienceDaily (Mar. 18, 2008) — Fungi do not have sexes, just so-called mating types. A new study shows that there are great similarities between the parts of DNA that determine the sex of plants and animals and the parts of DNA that determine mating types in certain fungi. This makes fungi interesting as new model organisms in studies of the evolutionary development of sex chromosomes.
In the plant and animal kingdoms there are individuals of different sexes, that is, bearers of either many tiny sex cells (males) or a few large ones (females). In the third eukaryote kingdom (organisms with DNA gathered in the cell nucleus), the fungi kingdom, there are no sexes but rather a simpler and more primitive system of different so-called mating types. These are distinguished by different variants of a few specific genes.
There are many ways to determine sex. In humans it is done by sex chromosomes. It is thought that this sex difference arose in the plant and animal kingdom from the simpler system of mating types and that this happened several times independently of each other throughout evolution. The change is believed to have happened with the inhibition of a step in the copying process in DNA, which led to two separate chromosomes. These then developed further over a long period of time.
"In humans, sex chromosomes are believed to have developed over the last 300 million years from a common 'proto-sex chromosome,'" says Hanna Johannesson, who directed the study.
The new study shows for the first time that even though fungi do not have sexes, there are many similarities between the parts of the genome that determine sex in plants and animals and the parts of the genome that control mating types in certain fungi. The research group specifically studied a spore sac fungus (Neurospora tetrasperma) and can show that the similarities are great, regarding both present-day structure and the way in which it arose.
"It's hard to study the evolution of sex chromosomes, partly because so many different and important sex-specific characters are tied to them. But much of this can be avoided if we use simpler systems, like fungi, as models."
This research was published in the journal PLoS March 17, 2008.
--------------------------------------------------------------------------------
Adapted from materials provided by Uppsala University, via EurekAlert!, a service of AAAS.
ScienceDaily (Mar. 18, 2008) — Fungi do not have sexes, just so-called mating types. A new study shows that there are great similarities between the parts of DNA that determine the sex of plants and animals and the parts of DNA that determine mating types in certain fungi. This makes fungi interesting as new model organisms in studies of the evolutionary development of sex chromosomes.
In the plant and animal kingdoms there are individuals of different sexes, that is, bearers of either many tiny sex cells (males) or a few large ones (females). In the third eukaryote kingdom (organisms with DNA gathered in the cell nucleus), the fungi kingdom, there are no sexes but rather a simpler and more primitive system of different so-called mating types. These are distinguished by different variants of a few specific genes.
There are many ways to determine sex. In humans it is done by sex chromosomes. It is thought that this sex difference arose in the plant and animal kingdom from the simpler system of mating types and that this happened several times independently of each other throughout evolution. The change is believed to have happened with the inhibition of a step in the copying process in DNA, which led to two separate chromosomes. These then developed further over a long period of time.
"In humans, sex chromosomes are believed to have developed over the last 300 million years from a common 'proto-sex chromosome,'" says Hanna Johannesson, who directed the study.
The new study shows for the first time that even though fungi do not have sexes, there are many similarities between the parts of the genome that determine sex in plants and animals and the parts of the genome that control mating types in certain fungi. The research group specifically studied a spore sac fungus (Neurospora tetrasperma) and can show that the similarities are great, regarding both present-day structure and the way in which it arose.
"It's hard to study the evolution of sex chromosomes, partly because so many different and important sex-specific characters are tied to them. But much of this can be avoided if we use simpler systems, like fungi, as models."
This research was published in the journal PLoS March 17, 2008.
--------------------------------------------------------------------------------
Adapted from materials provided by Uppsala University, via EurekAlert!, a service of AAAS.
Bread Mold Yields A Genome First For Filamentous Fungi; Neurospora’s 10,000 Genes Include RIPs That Limit New Genes
Bread Mold Yields A Genome First For Filamentous Fungi; Neurospora’s 10,000 Genes Include RIPs That Limit New Genes
ScienceDaily (Apr. 28, 2003) — ARLINGTON, Va. -- With more than 10,000 genes amid DNA strands of nearly 40 million base pairs, the first genome of a filamentous fungus has been sequenced through the cooperative efforts of a community of more than 70 scientists, culminating a two-year, $5 million effort supported by the National Science Foundation. The work is reported in this week's issue of Nature, which celebrates the 50th anniversary of that journal's publication of the structure of DNA.
At the center of this latest genetics achievement is a filamentous fungus, a bread mold, a life form easily overlooked in the shadow of the Human Genome Project. To biologists, however, it is Neurospora crassa, an organism of historic and enduring value as a model organism.
More than a decade before the structure of DNA was determined, two biologists focusing on Neurospora as a model genetic organism first established that genes provide the information for the creation of proteins. For their "one gene, one enzyme" hypothesis linking genes to biochemical function, the two scientists-- George Wells Beadle and Edward Lawri Tatum--received the Nobel Prize in 1941.
"The legacy of over 70 years of research, coupled with the availability of molecular and genetic tools, offers enormous potential for continued discovery," write the authors of the current Nature article. They call their genome sequence a "high quality draft," covering pretty much all but the 2 to 3 percent in "unusual genomic regions…that cannot be assembled readily with available techniques."
An organism's genome consists of the entire genetic code held in its DNA. With more than 5000 papers on Neurospora published in the past 30 years, having the genome now allows many previous biological studies to be seen in a new light.
Though initially billed as "not a research project, but a high throughput production effort," the sequencing effort nevertheless yielded new insights into light sensitivity, fungal growth, circadian rhythms, calcium-release mechanisms, and other basic cellular phenomena.
It also shed new light on the production of compounds called "secondary metabolites," such as pigments, antibiotics and toxins. The fungal world, with more than 250,000 species and inhabitants in every ecosystem on earth, produces a vast array of these small, bioactive compounds.
Fungi--slime molds and mushrooms among them--are used for food and for the production of industrial chemicals and enzymes. They also rot wood, damage fabric, obscure optics and, as pathogens, injure animals and plants.
Charting Neurospora's DNA sequence allowed scientists to examine a curious genetic mechanism unique to fungi known as repeat induced point mutation, or RIP. First discovered in Neurospora in the 1980s, the RIP process detects and mutates whole sections of DNA where it finds a duplication in the DNA, a condition that otherwise often leads to the creation of new genes. The authors suggest that "RIP has a powerful impact in suppressing the creation of these new genes or partial genes" and it may have "virtually arrested" the further evolution of Neurospora.
According to Maryanna Henkart, director for NSF's Division of Molecular and Cellular Biology, the evolution of the Neurospora sequencing effort itself has been driven by a sense of community among those who study the mold.
The first genome project on Neurospora began in 1995 under a five year NSF grant to the University of New Mexico to improve research opportunities for minorities. It involved 36 students preparing and sequencing the DNA of some specific genes. Most were Hispanic or Native American. The authors of the project's first paper included 17 undergraduates, several of whom are now with leading genome institutes.
"In 2000, the greater Neurospora community mobilized to find a way to get the complete genome sequence done," said Henkart. Teamed with Bruce Birren of the Whitehead Institute at Massachusetts Institute of Technology, they submitted an ambitious, ultimately successful, proposal.
Begun in September 2000, the project released its first batch of sequence data on Feb. 14, 2001, with additional segments subsequently released.
By its completion, it had involved collaborators from more than 30 universities and research groups, representing more than 10 U.S. states and six countries.
--------------------------------------------------------------------------------
Adapted from materials provided by National Science Foundation.
ScienceDaily (Apr. 28, 2003) — ARLINGTON, Va. -- With more than 10,000 genes amid DNA strands of nearly 40 million base pairs, the first genome of a filamentous fungus has been sequenced through the cooperative efforts of a community of more than 70 scientists, culminating a two-year, $5 million effort supported by the National Science Foundation. The work is reported in this week's issue of Nature, which celebrates the 50th anniversary of that journal's publication of the structure of DNA.
At the center of this latest genetics achievement is a filamentous fungus, a bread mold, a life form easily overlooked in the shadow of the Human Genome Project. To biologists, however, it is Neurospora crassa, an organism of historic and enduring value as a model organism.
More than a decade before the structure of DNA was determined, two biologists focusing on Neurospora as a model genetic organism first established that genes provide the information for the creation of proteins. For their "one gene, one enzyme" hypothesis linking genes to biochemical function, the two scientists-- George Wells Beadle and Edward Lawri Tatum--received the Nobel Prize in 1941.
"The legacy of over 70 years of research, coupled with the availability of molecular and genetic tools, offers enormous potential for continued discovery," write the authors of the current Nature article. They call their genome sequence a "high quality draft," covering pretty much all but the 2 to 3 percent in "unusual genomic regions…that cannot be assembled readily with available techniques."
An organism's genome consists of the entire genetic code held in its DNA. With more than 5000 papers on Neurospora published in the past 30 years, having the genome now allows many previous biological studies to be seen in a new light.
Though initially billed as "not a research project, but a high throughput production effort," the sequencing effort nevertheless yielded new insights into light sensitivity, fungal growth, circadian rhythms, calcium-release mechanisms, and other basic cellular phenomena.
It also shed new light on the production of compounds called "secondary metabolites," such as pigments, antibiotics and toxins. The fungal world, with more than 250,000 species and inhabitants in every ecosystem on earth, produces a vast array of these small, bioactive compounds.
Fungi--slime molds and mushrooms among them--are used for food and for the production of industrial chemicals and enzymes. They also rot wood, damage fabric, obscure optics and, as pathogens, injure animals and plants.
Charting Neurospora's DNA sequence allowed scientists to examine a curious genetic mechanism unique to fungi known as repeat induced point mutation, or RIP. First discovered in Neurospora in the 1980s, the RIP process detects and mutates whole sections of DNA where it finds a duplication in the DNA, a condition that otherwise often leads to the creation of new genes. The authors suggest that "RIP has a powerful impact in suppressing the creation of these new genes or partial genes" and it may have "virtually arrested" the further evolution of Neurospora.
According to Maryanna Henkart, director for NSF's Division of Molecular and Cellular Biology, the evolution of the Neurospora sequencing effort itself has been driven by a sense of community among those who study the mold.
The first genome project on Neurospora began in 1995 under a five year NSF grant to the University of New Mexico to improve research opportunities for minorities. It involved 36 students preparing and sequencing the DNA of some specific genes. Most were Hispanic or Native American. The authors of the project's first paper included 17 undergraduates, several of whom are now with leading genome institutes.
"In 2000, the greater Neurospora community mobilized to find a way to get the complete genome sequence done," said Henkart. Teamed with Bruce Birren of the Whitehead Institute at Massachusetts Institute of Technology, they submitted an ambitious, ultimately successful, proposal.
Begun in September 2000, the project released its first batch of sequence data on Feb. 14, 2001, with additional segments subsequently released.
By its completion, it had involved collaborators from more than 30 universities and research groups, representing more than 10 U.S. states and six countries.
--------------------------------------------------------------------------------
Adapted from materials provided by National Science Foundation.
Genome Sequence Of Fungus Reveals Unsuspected Ability To Use Complex Carbon Sources
Genome Sequence Of Fungus Reveals Unsuspected Ability To Use Complex Carbon Sources
ScienceDaily (May 6, 2008) — The model fungus Podospora anserina (P. anserina) has undergone substantial evolution since its separation from Neurospora crassa, as revealed from the Podospora draft genome sequence published in Genome Biology. The study also shows that the Podospora genome contains a large, highly specialised set of genes potentially involved in the breakdown of complex carbon sources, which may have potential use in biotechnology applications.
P. anserina is a dung-inhabiting, saprophytic fungus used to study areas of eukaryotic and fungal biology, including ageing and sexual development. Eric Espagne, Olivier Lespinet and Fabienne Malagnac from the Institute of Genetics and Microbiology in Paris and a team of researchers from France and The Netherlands used a whole genome shotgun and assembly approach to produce a 10X draft sequence of the fungus.
The researchers found evidence that P. anserina has undergone dynamic evolution since it diverged from its close relative N. crassa. They found evidence of extensive gene loss and gene shuffling, as well as substantial gene duplication. In addition, the transcription machinery of P. anserina produced a large number of RNAs that could potentially have regulatory roles. Further investigation of these non-conventional transcripts is required and could lead to the discovery of novel regulatory mechanisms, specifically during mycelium growth or accompanying the differentiation of the multicellular fructification produced during sexual reproduction.
The research team also discovered that P. anserina contains a large array of genes that may allow the fungus to use the natural carbon sources found wherever it grows. For example, the fungus carries genes potentially involved in the breakdown of the plant polymers cellulose and lignin, which may have future applications in biotechnology.
Espagne concludes: "As for other saprophytic fungi, the P. anserina genome sequence has opened new avenues in the comprehensive study of a variety of biological processes ... It also demonstrates how P. anserina is well adapted at the genome level to its natural environment, which was confirmed by the analysis of growth profiles. This result emphasizes the necessity to study several less well-tracked organisms in addition to those well known in the scientific community, as these may yield unexpected new insights into biological phenomena of general interest."
Journal reference: The genome sequence of the model ascomycete fungus Podospora anserina
Eric Espagne, Olivier Lespinet, Fabienne Malagnac, Corinne Da Silva, Olivier Jaillon, Betina M Porcel, Arnaud Couloux, Jean-Marc Aury, Béatrice Segurens, Julie Poulain, Véronique Anthouard, Sandrine Grossetete, Hamid Khalili, Evelyne Coppin, Michelle Déquart-Chablat, Marguerite Picard, Véronique Contamine, Sylvie Arnaise, Anne Bourdais, Véronique Berteaux-Lecellier, Daniel Gautheret, Ronald P de Vries, Evy Battaglia, Pedro M Coutinho, Etienne GJ Danchin, Bernard Henrissat, Ryiad El Khoury, Annie Sainsard-Chanet, Antoine Boivin, Bérangère Pinan-Lucarré, Carole H Sellem, Robert Debuchy, Patrick Wincker, Jean Weissenbach and Philippe Silar
Genome Biology (in press)
--------------------------------------------------------------------------------
Adapted from materials provided by Genome Biology, via EurekAlert!, a service of AAAS.
ScienceDaily (May 6, 2008) — The model fungus Podospora anserina (P. anserina) has undergone substantial evolution since its separation from Neurospora crassa, as revealed from the Podospora draft genome sequence published in Genome Biology. The study also shows that the Podospora genome contains a large, highly specialised set of genes potentially involved in the breakdown of complex carbon sources, which may have potential use in biotechnology applications.
P. anserina is a dung-inhabiting, saprophytic fungus used to study areas of eukaryotic and fungal biology, including ageing and sexual development. Eric Espagne, Olivier Lespinet and Fabienne Malagnac from the Institute of Genetics and Microbiology in Paris and a team of researchers from France and The Netherlands used a whole genome shotgun and assembly approach to produce a 10X draft sequence of the fungus.
The researchers found evidence that P. anserina has undergone dynamic evolution since it diverged from its close relative N. crassa. They found evidence of extensive gene loss and gene shuffling, as well as substantial gene duplication. In addition, the transcription machinery of P. anserina produced a large number of RNAs that could potentially have regulatory roles. Further investigation of these non-conventional transcripts is required and could lead to the discovery of novel regulatory mechanisms, specifically during mycelium growth or accompanying the differentiation of the multicellular fructification produced during sexual reproduction.
The research team also discovered that P. anserina contains a large array of genes that may allow the fungus to use the natural carbon sources found wherever it grows. For example, the fungus carries genes potentially involved in the breakdown of the plant polymers cellulose and lignin, which may have future applications in biotechnology.
Espagne concludes: "As for other saprophytic fungi, the P. anserina genome sequence has opened new avenues in the comprehensive study of a variety of biological processes ... It also demonstrates how P. anserina is well adapted at the genome level to its natural environment, which was confirmed by the analysis of growth profiles. This result emphasizes the necessity to study several less well-tracked organisms in addition to those well known in the scientific community, as these may yield unexpected new insights into biological phenomena of general interest."
Journal reference: The genome sequence of the model ascomycete fungus Podospora anserina
Eric Espagne, Olivier Lespinet, Fabienne Malagnac, Corinne Da Silva, Olivier Jaillon, Betina M Porcel, Arnaud Couloux, Jean-Marc Aury, Béatrice Segurens, Julie Poulain, Véronique Anthouard, Sandrine Grossetete, Hamid Khalili, Evelyne Coppin, Michelle Déquart-Chablat, Marguerite Picard, Véronique Contamine, Sylvie Arnaise, Anne Bourdais, Véronique Berteaux-Lecellier, Daniel Gautheret, Ronald P de Vries, Evy Battaglia, Pedro M Coutinho, Etienne GJ Danchin, Bernard Henrissat, Ryiad El Khoury, Annie Sainsard-Chanet, Antoine Boivin, Bérangère Pinan-Lucarré, Carole H Sellem, Robert Debuchy, Patrick Wincker, Jean Weissenbach and Philippe Silar
Genome Biology (in press)
--------------------------------------------------------------------------------
Adapted from materials provided by Genome Biology, via EurekAlert!, a service of AAAS.
Mushrooms As Good An Antioxidant Source As More Colorful Veggies
Mushrooms As Good An Antioxidant Source As More Colorful Veggies
ScienceDaily (June 27, 2006) — Portabella and crimini mushrooms rank with carrots, green beans, red peppers and broccoli as good sources of dietary antioxidants, Penn State researchers say.
N. Joy Dubost, who recently earned her doctorate in food science at Penn State, measured the activity of two antioxidants, polyphenols and ergothioneine, present in mushrooms, using the ORAC assay and HPLC instrumentation, as part of her dissertation research. She found that portabella mushrooms had an ORAC value of 9.7 micromoles of trolox equivalents per gram and criminis had an ORAC value of 9.5. Data available from other researchers shows carrots and green beans have an ORAC value of 5; red pepper 10; and broccoli 12.
The ORAC assay, the most well known test of antioxidant capacity, focuses on the peroxyl radical, the most predominate in the human body. Free radicals, such as the peroxyl radical, are thought to play a role in the aging process and in many diseases, including cancer, Alzheimer's and atherosclerosis. Epidemiological studies have shown that those who eat the most fruits and vegetables rich in antioxidants have lower incidence of these diseases.
Dubost detailed her results in a paper, Quantification of Polyphenols and Ergothioneine in Cultivated Mushrooms and Correlation to Total Antioxidant Capacity Using the ORAC and HORAC Assays, presented Monday, June 26, at the Institute of Food Technologists meeting in Orlando, Fl. Her co-author is her dissertation adviser, Dr. Robert Beelman, professor of food science.
Dubost explains that assays are a first step toward determining how effective a food is in providing protection against oxidative damage. Anti-oxidants inhibit increased rates of oxidation, which can damage proteins, lipids carbohydrates and DNA.
She adds, "The ORAC assay does not tell what happens in the human body but this assay is currently under investigation as to how it can predict physiological activity."
The Penn State study showed that the anti-oxidant effect of mushrooms is due primarily to the presence of polyphenols. Dubost and Beelman had earlier identified mushrooms as an abundant source of the anti-oxidant, ergothionene.
Dubost notes, "Evidence suggests that erogothioneine is biologically very important and, even though the assay used does not show it contributes to total antioxidant activity in the mushrooms, it may significantly contribute antioxidant activity in the body."
The ORAC values found in the latest study indicate that mushrooms are potent anti-oxidant sources. The research revealed that, of the mushrooms tested, portabella mushrooms and crimini mushrooms have the highest ORAC values. Criminis, which are brown, are otherwise similar to the popular white button mushroom, the one mostly commonly consumed in the U.S. The white button mushroom has an ORAC value of 6.9, above tomato, green pepper, pumpkin, zucchini, carrot, and green beans.
Dubost says, "You don't have to eat only the vegetables with the highest anti-oxidant capacity to benefit. If you eat a variety of mushrooms along with a variety of other vegetables, you'll be getting a variety of antioxidants."
The study was supported by The Mushroom Council, NutriCore Northeast and the Pennsylvania Agricultural Experiment Station.
--------------------------------------------------------------------------------
Adapted from materials provided by Penn State.
ScienceDaily (June 27, 2006) — Portabella and crimini mushrooms rank with carrots, green beans, red peppers and broccoli as good sources of dietary antioxidants, Penn State researchers say.
N. Joy Dubost, who recently earned her doctorate in food science at Penn State, measured the activity of two antioxidants, polyphenols and ergothioneine, present in mushrooms, using the ORAC assay and HPLC instrumentation, as part of her dissertation research. She found that portabella mushrooms had an ORAC value of 9.7 micromoles of trolox equivalents per gram and criminis had an ORAC value of 9.5. Data available from other researchers shows carrots and green beans have an ORAC value of 5; red pepper 10; and broccoli 12.
The ORAC assay, the most well known test of antioxidant capacity, focuses on the peroxyl radical, the most predominate in the human body. Free radicals, such as the peroxyl radical, are thought to play a role in the aging process and in many diseases, including cancer, Alzheimer's and atherosclerosis. Epidemiological studies have shown that those who eat the most fruits and vegetables rich in antioxidants have lower incidence of these diseases.
Dubost detailed her results in a paper, Quantification of Polyphenols and Ergothioneine in Cultivated Mushrooms and Correlation to Total Antioxidant Capacity Using the ORAC and HORAC Assays, presented Monday, June 26, at the Institute of Food Technologists meeting in Orlando, Fl. Her co-author is her dissertation adviser, Dr. Robert Beelman, professor of food science.
Dubost explains that assays are a first step toward determining how effective a food is in providing protection against oxidative damage. Anti-oxidants inhibit increased rates of oxidation, which can damage proteins, lipids carbohydrates and DNA.
She adds, "The ORAC assay does not tell what happens in the human body but this assay is currently under investigation as to how it can predict physiological activity."
The Penn State study showed that the anti-oxidant effect of mushrooms is due primarily to the presence of polyphenols. Dubost and Beelman had earlier identified mushrooms as an abundant source of the anti-oxidant, ergothionene.
Dubost notes, "Evidence suggests that erogothioneine is biologically very important and, even though the assay used does not show it contributes to total antioxidant activity in the mushrooms, it may significantly contribute antioxidant activity in the body."
The ORAC values found in the latest study indicate that mushrooms are potent anti-oxidant sources. The research revealed that, of the mushrooms tested, portabella mushrooms and crimini mushrooms have the highest ORAC values. Criminis, which are brown, are otherwise similar to the popular white button mushroom, the one mostly commonly consumed in the U.S. The white button mushroom has an ORAC value of 6.9, above tomato, green pepper, pumpkin, zucchini, carrot, and green beans.
Dubost says, "You don't have to eat only the vegetables with the highest anti-oxidant capacity to benefit. If you eat a variety of mushrooms along with a variety of other vegetables, you'll be getting a variety of antioxidants."
The study was supported by The Mushroom Council, NutriCore Northeast and the Pennsylvania Agricultural Experiment Station.
--------------------------------------------------------------------------------
Adapted from materials provided by Penn State.
Button Mushrooms Contain As Much Anti-oxidants As Expensive Ones
Button Mushrooms Contain As Much Anti-oxidants As Expensive Ones
ScienceDaily (Feb. 12, 2008) — The humble white button mushroom (Agaricus bisporus) has as much, and in some cases, more anti-oxidant properties than more expensive varieties.
Although the button mushroom is the foremost cultivated edible mushroom in the world with thousands of tonnes being eaten every year, it is often thought of as a poor relation to its more exotic and expensive cousins and to have lesser value nutritionally.
But according to new research in SCI's Journal of the Science of Food and Agriculture, the white button mushroom has as much anti-oxidant properties as its more expensive rivals, the maitake and the matsutake mushrooms - both of which are highly prized in Japanese cuisine for their reputed health properties including lowering blood pressure and their alleged ability to fight cancer.
Anti-oxidants are believed to help ward off illness and boost the body's immune system by acting as free radical scavengers, helping to mop up cell damage caused by free radicals.
Dr Jean-Michel Savoie and his team from the Institut National de la Recherche Agrinomique, a Governmental research institute in France, found that anti-radical activity was equivalent to, if not more, than the better known mushrooms when they measured the respective mushrooms' free radical scavenging ability.
The French team also found that the body of the mushroom had a higher concentration of anti-oxidants than the stalk.
Dr Jean-Michel said: "It can be reasonably assumed that white button mushrooms have as much, if not more, radical scavenging power as mushrooms currently touted for their health benefit. The good thing is button mushrooms are available all year round, are cheap and may be an excellent source of nutrition as part of a healthy diet."
--------------------------------------------------------------------------------
Adapted from materials provided by Society of Chemical Industry, via EurekAlert!, a service of AAAS.
ScienceDaily (Feb. 12, 2008) — The humble white button mushroom (Agaricus bisporus) has as much, and in some cases, more anti-oxidant properties than more expensive varieties.
Although the button mushroom is the foremost cultivated edible mushroom in the world with thousands of tonnes being eaten every year, it is often thought of as a poor relation to its more exotic and expensive cousins and to have lesser value nutritionally.
But according to new research in SCI's Journal of the Science of Food and Agriculture, the white button mushroom has as much anti-oxidant properties as its more expensive rivals, the maitake and the matsutake mushrooms - both of which are highly prized in Japanese cuisine for their reputed health properties including lowering blood pressure and their alleged ability to fight cancer.
Anti-oxidants are believed to help ward off illness and boost the body's immune system by acting as free radical scavengers, helping to mop up cell damage caused by free radicals.
Dr Jean-Michel Savoie and his team from the Institut National de la Recherche Agrinomique, a Governmental research institute in France, found that anti-radical activity was equivalent to, if not more, than the better known mushrooms when they measured the respective mushrooms' free radical scavenging ability.
The French team also found that the body of the mushroom had a higher concentration of anti-oxidants than the stalk.
Dr Jean-Michel said: "It can be reasonably assumed that white button mushrooms have as much, if not more, radical scavenging power as mushrooms currently touted for their health benefit. The good thing is button mushrooms are available all year round, are cheap and may be an excellent source of nutrition as part of a healthy diet."
--------------------------------------------------------------------------------
Adapted from materials provided by Society of Chemical Industry, via EurekAlert!, a service of AAAS.
Shiitake Mushrooms May Improve Human Immune Function, Especially If Grown On Old Oak Logs
Shiitake Mushrooms May Improve Human Immune Function, Especially If Grown On Old Oak Logs
ScienceDaily (June 29, 2008) — Shiitake (Lentinula edodes) mushrooms are good for you--and shiitake byproducts can be good for other crops.
These mushrooms contain high-molecular-weight polysaccharides (HMWP), which some studies suggest may improve human immune function. Other research indicates that the shiitake compound eritadenine may help lower cholesterol levels.
Agricultural Research Service (ARS) agronomist David Brauer has been studying shiitake production at the agency's Dale Bumpers Small Farm Research Center, Booneville, Ark. Working in collaboration with producers at the Shiitake Mushroom Center in Shirley, Ark., Brauer evaluated whether shiitakes grown on logs have higher levels of HMWP than shiitakes grown on commercial substrates.
The group inoculated logs with spores from three different shiitake varieties and compared the yield with shiitake yields grown on commercial substrates. They found that the log-grown shiitakes had HMWP levels as much as 70 percent higher than the substrate-grown shiitakes. The team also observed that shiitakes grown on red and white oak logs had higher levels of HMWP than shiitakes grown on sweet gum logs.
Logs used in shiitake production generally provide good yields for around two to three years. Larger shiitake farms may have 3,000 or more logs on the premises, and retire around 1,000 of them every year.
Not to let those used logs go to waste, Brauer’s team chipped a selection of spent logs, added urea and green grass cuttings to the chips and then composted the mixture. They found that the nitrogen levels in the resulting compost were comparable to nitrogen levels in other purchased soil amendment materials.
The researchers used the log compost to amend soil in a greenhouse spinach production system and found that the seedlings exhibited greater growth rates than seedlings cultivated in soil that had not been amended. Using recycled log compost provides another way for shiitake mushroom growers to increase their profits.
In 2004-2005, producers harvested approximately 9 million pounds of shiitake mushrooms, which sold for an average price of $3.21 per pound. Brauer’s findings lend a range of support to farmers interested in starting--or boosting profits from--log-grown shiitake production.
--------------------------------------------------------------------------------
Adapted from materials provided by USDA/ Agricultural Research Service.
ScienceDaily (June 29, 2008) — Shiitake (Lentinula edodes) mushrooms are good for you--and shiitake byproducts can be good for other crops.
These mushrooms contain high-molecular-weight polysaccharides (HMWP), which some studies suggest may improve human immune function. Other research indicates that the shiitake compound eritadenine may help lower cholesterol levels.
Agricultural Research Service (ARS) agronomist David Brauer has been studying shiitake production at the agency's Dale Bumpers Small Farm Research Center, Booneville, Ark. Working in collaboration with producers at the Shiitake Mushroom Center in Shirley, Ark., Brauer evaluated whether shiitakes grown on logs have higher levels of HMWP than shiitakes grown on commercial substrates.
The group inoculated logs with spores from three different shiitake varieties and compared the yield with shiitake yields grown on commercial substrates. They found that the log-grown shiitakes had HMWP levels as much as 70 percent higher than the substrate-grown shiitakes. The team also observed that shiitakes grown on red and white oak logs had higher levels of HMWP than shiitakes grown on sweet gum logs.
Logs used in shiitake production generally provide good yields for around two to three years. Larger shiitake farms may have 3,000 or more logs on the premises, and retire around 1,000 of them every year.
Not to let those used logs go to waste, Brauer’s team chipped a selection of spent logs, added urea and green grass cuttings to the chips and then composted the mixture. They found that the nitrogen levels in the resulting compost were comparable to nitrogen levels in other purchased soil amendment materials.
The researchers used the log compost to amend soil in a greenhouse spinach production system and found that the seedlings exhibited greater growth rates than seedlings cultivated in soil that had not been amended. Using recycled log compost provides another way for shiitake mushroom growers to increase their profits.
In 2004-2005, producers harvested approximately 9 million pounds of shiitake mushrooms, which sold for an average price of $3.21 per pound. Brauer’s findings lend a range of support to farmers interested in starting--or boosting profits from--log-grown shiitake production.
--------------------------------------------------------------------------------
Adapted from materials provided by USDA/ Agricultural Research Service.
Biofuels: Fungus Use Improves Corn-to-ethanol Process
Biofuels: Fungus Use Improves Corn-to-ethanol Process
ScienceDaily (May 30, 2008) — Growing a fungus in some of the leftovers from ethanol production can save energy, recycle more water and improve the livestock feed that's a co-product of fuel production, according to a team of researchers from Iowa State University and the University of Hawai'i.
"The process could change ethanol production in dry-grind plants so much that energy costs can be reduced by as much as one-third," said Hans van Leeuwen, an Iowa State professor of civil, construction and environmental engineering and the leader of the research project.
Van Leeuwen and the other researchers developing the technology -- Anthony L. Pometto III, a professor of food science and human nutrition; Mary Rasmussen, a graduate student in environmental engineering and biorenewable resources and technology; and Samir Khanal, a former Iowa State research assistant professor who's now an assistant professor of molecular biosciences and bioengineering at the University of Hawai'i at Manoa -- recently won the 2008 Grand Prize for University Research from the American Academy of Environmental Engineers for the project.
"Those chosen for prizes by an independent panel of distinguished experts address the broad range of modern challenges inherent in providing life-nurturing services for humans and protection of the environment," according to a statement from the academy. "... Their innovations and performance illustrate the essential role of environmental engineers in providing a healthy planet."
The Iowa State project is focused on using fungi to clean up and improve the dry-grind ethanol production process. That process grinds corn kernels and adds water and enzymes. The enzymes break the starches into sugars. The sugars are fermented with yeasts to produce ethanol.
The fuel is recovered by distillation, but there are about six gallons of leftovers for every gallon of fuel that's produced. Those leftovers, known as stillage, contain solids and other organic material. Most of the solids are removed by centrifugation and dried into distillers dried grains that are sold as livestock feed, primarily for cattle.
The remaining liquid, known as thin stillage, still contains some solids, a variety of organic compounds from corn and fermentation as well as enzymes. Because the compounds and solids can interfere with ethanol production, only about 50 percent of thin stillage can be recycled back into ethanol production. The rest is evaporated and blended with distillers dried grains to produce distillers dried grains with solubles.
The researchers added a fungus, Rhizopus microsporus, to the thin stillage and found it would feed and grow. The fungus removes about 80 percent of the organic material and all of the solids in the thin stillage, allowing the water and enzymes in the thin stillage to be recycled back into production.
The fungus can also be harvested. It's a food-grade organism that's rich in protein, certain essential amino acids and other nutrients. It can be dried and sold as a livestock feed supplement. Or it can be blended with distillers dried grains to boost its value as a livestock feed and make it more suitable for feeding hogs and chickens.
Van Leeuwen said all of that can save United States ethanol producers a lot of energy and money at current production levels:
Eliminating the need to evaporate thin stillage would save ethanol plants up to $800 million a year in energy costs.
Allowing more water recycling would reduce the industry's water consumption by as much as 10 billion gallons per year. And it allows producers to recycle enzymes in the thin stillage, saving about $60 million per year.
Adding value and nutrients to the livestock feed produced by ethanol plants would grow the market for that feed by about $400 million per year.
And the researchers' fungal process would improve the energy balance of ethanol production by reducing energy inputs so there is more of an energy gain.
Van Leeuwen estimated it would cost $11 million to start using the process in an ethanol plant that produces 100 million gallons of fuel per year. But, he said the cost savings at such a plant could pay off that investment in about six months.
The Iowa State research project is supported by grants of $78,806 from the Grow Iowa Values Fund, a state economic development program, and $80,000 from the U.S. Department of Agriculture through the Iowa Biotechnology Byproducts Consortium.
The researchers have filed for a patent on the technology and are looking for investors to commercialize the invention. And while the process needs to be proven at larger scales, there are high hopes it can do a lot to improve the efficiency of ethanol production.
"We will be saving ethanol producers money and energy," Pometto said. "That's the bottom line."
--------------------------------------------------------------------------------
Adapted from materials provided by Iowa State University.
ScienceDaily (May 30, 2008) — Growing a fungus in some of the leftovers from ethanol production can save energy, recycle more water and improve the livestock feed that's a co-product of fuel production, according to a team of researchers from Iowa State University and the University of Hawai'i.
"The process could change ethanol production in dry-grind plants so much that energy costs can be reduced by as much as one-third," said Hans van Leeuwen, an Iowa State professor of civil, construction and environmental engineering and the leader of the research project.
Van Leeuwen and the other researchers developing the technology -- Anthony L. Pometto III, a professor of food science and human nutrition; Mary Rasmussen, a graduate student in environmental engineering and biorenewable resources and technology; and Samir Khanal, a former Iowa State research assistant professor who's now an assistant professor of molecular biosciences and bioengineering at the University of Hawai'i at Manoa -- recently won the 2008 Grand Prize for University Research from the American Academy of Environmental Engineers for the project.
"Those chosen for prizes by an independent panel of distinguished experts address the broad range of modern challenges inherent in providing life-nurturing services for humans and protection of the environment," according to a statement from the academy. "... Their innovations and performance illustrate the essential role of environmental engineers in providing a healthy planet."
The Iowa State project is focused on using fungi to clean up and improve the dry-grind ethanol production process. That process grinds corn kernels and adds water and enzymes. The enzymes break the starches into sugars. The sugars are fermented with yeasts to produce ethanol.
The fuel is recovered by distillation, but there are about six gallons of leftovers for every gallon of fuel that's produced. Those leftovers, known as stillage, contain solids and other organic material. Most of the solids are removed by centrifugation and dried into distillers dried grains that are sold as livestock feed, primarily for cattle.
The remaining liquid, known as thin stillage, still contains some solids, a variety of organic compounds from corn and fermentation as well as enzymes. Because the compounds and solids can interfere with ethanol production, only about 50 percent of thin stillage can be recycled back into ethanol production. The rest is evaporated and blended with distillers dried grains to produce distillers dried grains with solubles.
The researchers added a fungus, Rhizopus microsporus, to the thin stillage and found it would feed and grow. The fungus removes about 80 percent of the organic material and all of the solids in the thin stillage, allowing the water and enzymes in the thin stillage to be recycled back into production.
The fungus can also be harvested. It's a food-grade organism that's rich in protein, certain essential amino acids and other nutrients. It can be dried and sold as a livestock feed supplement. Or it can be blended with distillers dried grains to boost its value as a livestock feed and make it more suitable for feeding hogs and chickens.
Van Leeuwen said all of that can save United States ethanol producers a lot of energy and money at current production levels:
Eliminating the need to evaporate thin stillage would save ethanol plants up to $800 million a year in energy costs.
Allowing more water recycling would reduce the industry's water consumption by as much as 10 billion gallons per year. And it allows producers to recycle enzymes in the thin stillage, saving about $60 million per year.
Adding value and nutrients to the livestock feed produced by ethanol plants would grow the market for that feed by about $400 million per year.
And the researchers' fungal process would improve the energy balance of ethanol production by reducing energy inputs so there is more of an energy gain.
Van Leeuwen estimated it would cost $11 million to start using the process in an ethanol plant that produces 100 million gallons of fuel per year. But, he said the cost savings at such a plant could pay off that investment in about six months.
The Iowa State research project is supported by grants of $78,806 from the Grow Iowa Values Fund, a state economic development program, and $80,000 from the U.S. Department of Agriculture through the Iowa Biotechnology Byproducts Consortium.
The researchers have filed for a patent on the technology and are looking for investors to commercialize the invention. And while the process needs to be proven at larger scales, there are high hopes it can do a lot to improve the efficiency of ethanol production.
"We will be saving ethanol producers money and energy," Pometto said. "That's the bottom line."
--------------------------------------------------------------------------------
Adapted from materials provided by Iowa State University.
Knowledge Of Nitrogen Transfer Between Plants And Beneficial Fungi Expands
Knowledge Of Nitrogen Transfer Between Plants And Beneficial Fungi Expands
ScienceDaily (June 23, 2005) — New findings show that a beneficial soil fungus plays a large role in nitrogen uptake and utilization in most plants.
In a recent issue of the journal Nature, Agricultural Research Service (ARS) chemist Philip E. Pfeffer and cooperators report that beneficial arbuscular mycorrhizal (AM) fungi transfer substantial amounts of nitrogen to their plant hosts. A lack of soil nitrogen often limits plant growth.
The studies were conducted by Pfeffer and David Douds at the ARS Eastern Regional Research Center, Wyndmoor, Pa.; Michigan State University scientists headed by Yair Shachar-Hill; and New Mexico State University scientists headed by Peter J. Lammers and including graduate student Manjula Govindarajulu.
AM is the most common type of symbiotic fungus that colonizes the roots of most crop plants. The fungi receive glucose and possibly other organic materials from the plant, while enhancing the plant's ability to take up mineral nutrients, primarily phosphorus.
The scientists previously identified enzymes and genes involved in nitrogen absorption and breakdown in AM fungi, but very little was known about how nitrogen is moved from fungus to plant or in which form nitrogen moves within the fungus.
The researchers discovered a novel metabolic pathway in which inorganic nitrogen is taken up by the fungi and incorporated into an amino acid called arginine. This amino acid remains in the fungus until it is broken down and transferred to the plant.
The results show that the symbiotic relationship between mycorrhizal fungi and plants may have a much more significant role in the worldwide nitrogen cycle than previously believed. With this in mind, farmers may benefit from promoting the proliferation of mycorrhizal fungi through diminished fertilizer input, thereby making more efficient use of the nitrogen stores in agricultural soils.
ARS is the U.S. Department of Agriculture's chief scientific research agency.
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Adapted from materials provided by USDA / Agricultural Research Service.
ScienceDaily (June 23, 2005) — New findings show that a beneficial soil fungus plays a large role in nitrogen uptake and utilization in most plants.
In a recent issue of the journal Nature, Agricultural Research Service (ARS) chemist Philip E. Pfeffer and cooperators report that beneficial arbuscular mycorrhizal (AM) fungi transfer substantial amounts of nitrogen to their plant hosts. A lack of soil nitrogen often limits plant growth.
The studies were conducted by Pfeffer and David Douds at the ARS Eastern Regional Research Center, Wyndmoor, Pa.; Michigan State University scientists headed by Yair Shachar-Hill; and New Mexico State University scientists headed by Peter J. Lammers and including graduate student Manjula Govindarajulu.
AM is the most common type of symbiotic fungus that colonizes the roots of most crop plants. The fungi receive glucose and possibly other organic materials from the plant, while enhancing the plant's ability to take up mineral nutrients, primarily phosphorus.
The scientists previously identified enzymes and genes involved in nitrogen absorption and breakdown in AM fungi, but very little was known about how nitrogen is moved from fungus to plant or in which form nitrogen moves within the fungus.
The researchers discovered a novel metabolic pathway in which inorganic nitrogen is taken up by the fungi and incorporated into an amino acid called arginine. This amino acid remains in the fungus until it is broken down and transferred to the plant.
The results show that the symbiotic relationship between mycorrhizal fungi and plants may have a much more significant role in the worldwide nitrogen cycle than previously believed. With this in mind, farmers may benefit from promoting the proliferation of mycorrhizal fungi through diminished fertilizer input, thereby making more efficient use of the nitrogen stores in agricultural soils.
ARS is the U.S. Department of Agriculture's chief scientific research agency.
--------------------------------------------------------------------------------
Adapted from materials provided by USDA / Agricultural Research Service.
Learning More About Beneficial Soil Fungi
Learning More About Beneficial Soil Fungi
ScienceDaily (Feb. 2, 2006) — Beneficial soil fungi that help plants grow could become easier for farmers to use, based on research by Agricultural Research Service (ARS) scientists who are studying these valuable organisms.
The fungi, called mycorrhizal fungi, live inside and outside root cells and help them reach for nutrients by extending long threads called hyphae into the soil. The plant, in exchange, provides the fungi glucose and possibly other organic materials that they need to survive. Unfortunately, modern agricultural practices have reduced populations of arbuscular mycorrhizal (AM) fungi, the most common type.
By learning more about AM fungi physiology and finding ways to grow colonies without host plants, ARS scientists at the Eastern Regional Research Center in Wyndmoor, Pa., hope to make the fungi a practical option for producers.
Currently, researchers cannot cultivate an AM fungus without a host because the fungus can't complete its life cycle without the organic nutrients or other stimuli it receives from roots. Gerald Nagahashi, a chemist/cell biologist at ERRC, has been focusing on the events that must occur before the fungus can colonize a host plant.
He developed a bioassay showing that host root components--including chemical compounds exuding from the roots, root caps and root border cells--induce fungal hyphal branching. The increase in branching creates a greater potential for the fungus to find and attach to the host root surface.
Nagahashi and David D. Douds, an ERRC microbiologist, investigated how environmental factors, such as chemical compounds from host roots, blue light from the sun�s spectrum, and carbon dioxide, affect AM fungal growth, either individually or together.
Their techniques involved growing host roots in sterile culture and using sterile fungal spores to study various environmental factors individually or in combination. They found that these three factors--root chemicals, blue light and carbon dioxide--can all work independently to promote growth in AM fungi but are even more effective when applied together.
###
ARS is the U.S. Department of Agriculture's chief scientific research agency.
--------------------------------------------------------------------------------
Adapted from materials provided by USDA/Agricultural Research Service.
ScienceDaily (Feb. 2, 2006) — Beneficial soil fungi that help plants grow could become easier for farmers to use, based on research by Agricultural Research Service (ARS) scientists who are studying these valuable organisms.
The fungi, called mycorrhizal fungi, live inside and outside root cells and help them reach for nutrients by extending long threads called hyphae into the soil. The plant, in exchange, provides the fungi glucose and possibly other organic materials that they need to survive. Unfortunately, modern agricultural practices have reduced populations of arbuscular mycorrhizal (AM) fungi, the most common type.
By learning more about AM fungi physiology and finding ways to grow colonies without host plants, ARS scientists at the Eastern Regional Research Center in Wyndmoor, Pa., hope to make the fungi a practical option for producers.
Currently, researchers cannot cultivate an AM fungus without a host because the fungus can't complete its life cycle without the organic nutrients or other stimuli it receives from roots. Gerald Nagahashi, a chemist/cell biologist at ERRC, has been focusing on the events that must occur before the fungus can colonize a host plant.
He developed a bioassay showing that host root components--including chemical compounds exuding from the roots, root caps and root border cells--induce fungal hyphal branching. The increase in branching creates a greater potential for the fungus to find and attach to the host root surface.
Nagahashi and David D. Douds, an ERRC microbiologist, investigated how environmental factors, such as chemical compounds from host roots, blue light from the sun�s spectrum, and carbon dioxide, affect AM fungal growth, either individually or together.
Their techniques involved growing host roots in sterile culture and using sterile fungal spores to study various environmental factors individually or in combination. They found that these three factors--root chemicals, blue light and carbon dioxide--can all work independently to promote growth in AM fungi but are even more effective when applied together.
###
ARS is the U.S. Department of Agriculture's chief scientific research agency.
--------------------------------------------------------------------------------
Adapted from materials provided by USDA/Agricultural Research Service.
'Silent' Fungus Metabolism Awakened For New Natural Products
'Silent' Fungus Metabolism Awakened For New Natural Products
ScienceDaily (May 1, 2008) — US scientists have re-awakened ‘silent’ metabolic pathways in fungi to reveal a new range of natural products. The research could provide not only a source of new drugs, but a way to “listen to what fungi are saying” to organisms around them.
Fungi produce a wide variety of natural products, including potent toxins – for example, the amanitins, primarily responsible for the toxicity of the death cap fungus – and life-saving drugs such as penicillin. As a result, the genetics of fungi have generated much interest in recent years.
Now, Robert Cichewicz and colleagues at the University of Oklahoma, Norman, US, have shown that metabolic pathways that are normally ‘silent’ can be re-activated to make new compounds, in work published in the Royal Society of Chemistry journal Organic & Biomolecular Chemistry.
Many fungi have a wealth of genes encoding for far more natural products than they actually produce, says Cichewicz. The explanation is thought to be that when fungi do not need certain compounds, they inhibit the transcription of the DNA that codes for the proteins that make them, preventing their biosynthesis.
Knowing what these mystery compounds are could be very important for the development of new medicines, as well as for helping us to understand the ecological roles that fungi play, claims Cichewicz.
The DNA involved is inhibited by being scrunched up in a globular form called heterochromatin. To activate this DNA and turn on these ‘silent’ natural product pathways, the team decided to treat fungal cultures with small molecules that interfere with the formation of the heterochromatin – allowing the DNA to be transcripted.
To show their idea in action, the researchers took a culture of Cladosporium cladosporioides, a tidal pool fungus, and treated it separately with 5-azacytidine and suberoylanilide hydroxamic acid. Both treatments, says Cichewicz, dramatically changed the natural product output of the fungus, with two completely new natural products being isolated.
The new approach impresses Jon Clardy at the Harvard Medical School, Boston, US, who says that it could ‘greatly expand the suite of biologically active small molecules obtained from fungi’ and that it ‘capitalises on recent developments in drug discovery to increase the odds of discovering new drugs’.
The results also have important implications for research into fungi and other microorganisms, explains Cichewicz. Natural products are the means by which fungi ‘communicate’ with organisms around them, so we are in essence, he says, ‘discovering chemical means for listening to what fungi are saying’.
Journal reference: Russell Williams et al., Org. Biomol. Chem., 2008, DOI: 10.1039/b804701d
ScienceDaily (May 1, 2008) — US scientists have re-awakened ‘silent’ metabolic pathways in fungi to reveal a new range of natural products. The research could provide not only a source of new drugs, but a way to “listen to what fungi are saying” to organisms around them.
Fungi produce a wide variety of natural products, including potent toxins – for example, the amanitins, primarily responsible for the toxicity of the death cap fungus – and life-saving drugs such as penicillin. As a result, the genetics of fungi have generated much interest in recent years.
Now, Robert Cichewicz and colleagues at the University of Oklahoma, Norman, US, have shown that metabolic pathways that are normally ‘silent’ can be re-activated to make new compounds, in work published in the Royal Society of Chemistry journal Organic & Biomolecular Chemistry.
Many fungi have a wealth of genes encoding for far more natural products than they actually produce, says Cichewicz. The explanation is thought to be that when fungi do not need certain compounds, they inhibit the transcription of the DNA that codes for the proteins that make them, preventing their biosynthesis.
Knowing what these mystery compounds are could be very important for the development of new medicines, as well as for helping us to understand the ecological roles that fungi play, claims Cichewicz.
The DNA involved is inhibited by being scrunched up in a globular form called heterochromatin. To activate this DNA and turn on these ‘silent’ natural product pathways, the team decided to treat fungal cultures with small molecules that interfere with the formation of the heterochromatin – allowing the DNA to be transcripted.
To show their idea in action, the researchers took a culture of Cladosporium cladosporioides, a tidal pool fungus, and treated it separately with 5-azacytidine and suberoylanilide hydroxamic acid. Both treatments, says Cichewicz, dramatically changed the natural product output of the fungus, with two completely new natural products being isolated.
The new approach impresses Jon Clardy at the Harvard Medical School, Boston, US, who says that it could ‘greatly expand the suite of biologically active small molecules obtained from fungi’ and that it ‘capitalises on recent developments in drug discovery to increase the odds of discovering new drugs’.
The results also have important implications for research into fungi and other microorganisms, explains Cichewicz. Natural products are the means by which fungi ‘communicate’ with organisms around them, so we are in essence, he says, ‘discovering chemical means for listening to what fungi are saying’.
Journal reference: Russell Williams et al., Org. Biomol. Chem., 2008, DOI: 10.1039/b804701d
Fungus That Produces Biofuels From Plants: Genome Sequenced
Fungus That Produces Biofuels From Plants: Genome Sequenced
ScienceDaily (May 21, 2008) — The fungus Trichoderma reesei optimally breaks down plants into simple sugars, the basic components of ethanol. The fungus's genome has recently been sequenced by researchers from the Architecture et fonction des macromolécules biologiques laboratory (CNRS/Université de la Méditerranée and Universite de Provence), working together with an American team. The results show that only a few genes are responsible for the fungus's enzymatic activity. They offer new avenues for the fabrication of second generation biofuels from plant waste.
The fungus Trichoderma reesei was discovered in the South Pacific during the Second World War, where it was damaging American military equipment and was defeating every attempt at protecting the equipment with cotton cloth. The fungus contains a number of enzymes, cellulases, with potent catalytic properties that break down plants. It is considered to be the world’s most efficient fungus at breaking down the cellulose in plant cell walls into simple sugars, which it feeds on.
After fermentation, simple sugars can easily be transformed into biofuels such as ethanol. First generation agrofuels, made from grain or from beet, have certain limitations. Second generation biofuels, made from foresting and agricultural waste (tree cuttings, corn cobs, straw, etc.) do not have these limitations, as they complement pre-established agricultural activity, have a better CO2 balance, et don’t interfere with the agro-alimentary cycle. To produce these second generation biofuels, industrialists are looking to develop fungus strains capable of producing a cocktail of cellulases and hemicellulases at a concentration of 50 g/l. Trichoderma reesei is the choice organism for most projects in this field.
Bernard Henrissat’s glycogenomic team at the Architecture et fonction des macromolécules biologiques lab specializes in the study of enzymes which break down sugars.* In order to learn more about the incredible enzymatic activity of Trichoderma reesei, they assayed its genome. They found that the fungus has an unexpectedly small number of genes encoding cellulases (hemicellulases and pectinases), many fewer in fact than in usually found in fungi capable of breaking down plant cell walls. Moreover, the fungus has no or very little enzymatic activity allowing the digestion of specific components in the cell wall.
This was first interpreted as bad news, but the limitations of this model organism are now being seen as something positive. The fungus’s enzyme cocktail lends itself to numerous genetic modifications, and researchers are looking into which other enzymes can be added to the fungus’s gene sequence in order to make it even more efficient at producing bioethanol.
*The laboratory has a perfected Carbohydrate-Active Enzymes (CAZy) database which describes a number of enzyme families which form and destroy bonds between sugars.
--------------------------------------------------------------------------------
Journal reference:
Diego Martinez, Randy M Berka, Bernard Henrissat, Markku Saloheimo, Mikko Arvas, Scott E Baker, Jarod Chapman, Olga Chertkov, Pedro M Coutinho, Dan Cullen, Etienne G J Danchin, Igor V Grigoriev, Paul Harris, Melissa Jackson, Christian P Kubicek, Cliff S Han, Isaac Ho, Luis F Larrondo, Alfredo Lopez de Leon, Jon K Magnuson, Sandy Merino, Monica Misra, Beth Nelson, Nicholas Putnam, Barbara Robbertse, Asaf A Salamov, Monika Schmoll, Astrid Terry, Nina Thayer, Ann Westerholm-Parvinen, Conrad L Schoch, Jian Yao, Ravi Barbote, Mary Anne Nelson, Chris Detter, David Bruce, Cheryl R Kuske, Gary Xie, Paul Richardson, Daniel S Rokhsar, Susan M Lucas, Edward M Rubin, Nigel Dunn-Coleman, Michael Ward & Thomas S Brettin. Genome sequencing and analysis of the biomass-degrading fungus Trichoderma reesei (syn. Hypocrea jecorina). Nature Biotechnology 26, 553 - 560 (2008) 4 May 2008 doi:10.1038/nbt1403 [link]
Adapted from materials provided by CNRS.
ScienceDaily (May 21, 2008) — The fungus Trichoderma reesei optimally breaks down plants into simple sugars, the basic components of ethanol. The fungus's genome has recently been sequenced by researchers from the Architecture et fonction des macromolécules biologiques laboratory (CNRS/Université de la Méditerranée and Universite de Provence), working together with an American team. The results show that only a few genes are responsible for the fungus's enzymatic activity. They offer new avenues for the fabrication of second generation biofuels from plant waste.
The fungus Trichoderma reesei was discovered in the South Pacific during the Second World War, where it was damaging American military equipment and was defeating every attempt at protecting the equipment with cotton cloth. The fungus contains a number of enzymes, cellulases, with potent catalytic properties that break down plants. It is considered to be the world’s most efficient fungus at breaking down the cellulose in plant cell walls into simple sugars, which it feeds on.
After fermentation, simple sugars can easily be transformed into biofuels such as ethanol. First generation agrofuels, made from grain or from beet, have certain limitations. Second generation biofuels, made from foresting and agricultural waste (tree cuttings, corn cobs, straw, etc.) do not have these limitations, as they complement pre-established agricultural activity, have a better CO2 balance, et don’t interfere with the agro-alimentary cycle. To produce these second generation biofuels, industrialists are looking to develop fungus strains capable of producing a cocktail of cellulases and hemicellulases at a concentration of 50 g/l. Trichoderma reesei is the choice organism for most projects in this field.
Bernard Henrissat’s glycogenomic team at the Architecture et fonction des macromolécules biologiques lab specializes in the study of enzymes which break down sugars.* In order to learn more about the incredible enzymatic activity of Trichoderma reesei, they assayed its genome. They found that the fungus has an unexpectedly small number of genes encoding cellulases (hemicellulases and pectinases), many fewer in fact than in usually found in fungi capable of breaking down plant cell walls. Moreover, the fungus has no or very little enzymatic activity allowing the digestion of specific components in the cell wall.
This was first interpreted as bad news, but the limitations of this model organism are now being seen as something positive. The fungus’s enzyme cocktail lends itself to numerous genetic modifications, and researchers are looking into which other enzymes can be added to the fungus’s gene sequence in order to make it even more efficient at producing bioethanol.
*The laboratory has a perfected Carbohydrate-Active Enzymes (CAZy) database which describes a number of enzyme families which form and destroy bonds between sugars.
--------------------------------------------------------------------------------
Journal reference:
Diego Martinez, Randy M Berka, Bernard Henrissat, Markku Saloheimo, Mikko Arvas, Scott E Baker, Jarod Chapman, Olga Chertkov, Pedro M Coutinho, Dan Cullen, Etienne G J Danchin, Igor V Grigoriev, Paul Harris, Melissa Jackson, Christian P Kubicek, Cliff S Han, Isaac Ho, Luis F Larrondo, Alfredo Lopez de Leon, Jon K Magnuson, Sandy Merino, Monica Misra, Beth Nelson, Nicholas Putnam, Barbara Robbertse, Asaf A Salamov, Monika Schmoll, Astrid Terry, Nina Thayer, Ann Westerholm-Parvinen, Conrad L Schoch, Jian Yao, Ravi Barbote, Mary Anne Nelson, Chris Detter, David Bruce, Cheryl R Kuske, Gary Xie, Paul Richardson, Daniel S Rokhsar, Susan M Lucas, Edward M Rubin, Nigel Dunn-Coleman, Michael Ward & Thomas S Brettin. Genome sequencing and analysis of the biomass-degrading fungus Trichoderma reesei (syn. Hypocrea jecorina). Nature Biotechnology 26, 553 - 560 (2008) 4 May 2008 doi:10.1038/nbt1403 [link]
Adapted from materials provided by CNRS.
Fungi Have A Hand In Depleted Uranium's Environmental Fate
Fungi Have A Hand In Depleted Uranium's Environmental Fate
ScienceDaily (May 6, 2008) — Fungi may have an important role to play in the fate of potentially dangerous depleted uranium left in the environment after recent war campaigns, according to a new report in the May 6th issue of Current Biology, a publication of Cell Press.
The researchers found evidence that fungi can "lock" depleted uranium into a mineral form that may be less likely to find its way into plants, animals, or the water supply.
"This work provides yet another example of the incredible properties of microorganisms in effecting transformations of metals and minerals in the natural environment," said Geoffrey Gadd of the University of Dundee in Scotland. "Because fungi are perfectly suited as biogeochemical agents, often dominate the biota in polluted soils, and play a major role in the establishment and survival of plants through their association with roots, fungal-based approaches should not be neglected in remediation attempts for metal-polluted soils."
The testing of depleted-uranium ammunition and its recent use in Iraq and the Balkans has led to contamination of the environment with the unstable metal, Gadd explained. Depleted uranium differs from natural uranium in the balance of isotopes it contains. It is the byproduct of uranium enrichment for use in nuclear reactors or nuclear weapons and is valued for its very high density. Although less radioactive than natural uranium, depleted uranium is just as toxic and poses a threat to people.
In the new study, the researchers found that free-living and plant symbiotic (mycorrhizal) fungi can colonize depleted-uranium surfaces and transform the metal into uranyl phosphate minerals.
While they probably still pose some threat, he said, "The fungal-produced minerals are capable of long-term uranium retention, so this may help prevent uptake of uranium by plants, animals, and microbes. It might also prevent the spent uranium from leaching out from the soil."
Gadd said that a combination of environmental and biological factors is involved in the process. First, the unstable uranium metal gets coated with a layer of oxides. Moisture in the environment also "corrodes" the depleted uranium, encouraging fungal colonization and growth. While the fungi grow, they produce acidic substances, which corrode the depleted uranium even further. Some of the substances produced include organic acids that convert the uranium into a form that the fungi can take up or that can interact with other compounds. Ultimately, he said, the interaction of soluble forms of uranium with phosphate leads to the formation of the new uranium minerals that get deposited around the fungal biomass.
"We have shown for the first time that fungi can transform metallic uranium into minerals, which are capable of long-term uranium retention," the researchers concluded. "This phenomenon could be relevant to the future development of various remediation and revegetation techniques for uranium-polluted soils."
The researchers include Marina Fomina of University of Dundee in Dundee, Scotland; John M. Charnock of Synchrotron Radiation Source (SRS) Daresbury Laboratory in Daresbury, Warrington, Cheshire; Stephen Hillier of Macaulay Institute in Craigiebuckler, Aberdeen, Scotland; Rebeca Alvarez and Francis Livens of University of Manchester in Manchester, UK; and Geoffrey M. Gadd of University of Dundee in Dundee, Scotland.
This work was financially supported by the MOD/NERC DU Programme (Grant NE/C506799/1), CCLRC Daresbury SRS (SRS beamtime allocation 45100), and the Scottish Executive Environmental and Rural Affairs Department (SEERAD).
Journal reference: Fomina et al.: "Role of fungi in the biogeochemical fate of depleted uranium." Publishing in Current Biology 18, R375 --R377, May 6, 2008.
ScienceDaily (May 6, 2008) — Fungi may have an important role to play in the fate of potentially dangerous depleted uranium left in the environment after recent war campaigns, according to a new report in the May 6th issue of Current Biology, a publication of Cell Press.
The researchers found evidence that fungi can "lock" depleted uranium into a mineral form that may be less likely to find its way into plants, animals, or the water supply.
"This work provides yet another example of the incredible properties of microorganisms in effecting transformations of metals and minerals in the natural environment," said Geoffrey Gadd of the University of Dundee in Scotland. "Because fungi are perfectly suited as biogeochemical agents, often dominate the biota in polluted soils, and play a major role in the establishment and survival of plants through their association with roots, fungal-based approaches should not be neglected in remediation attempts for metal-polluted soils."
The testing of depleted-uranium ammunition and its recent use in Iraq and the Balkans has led to contamination of the environment with the unstable metal, Gadd explained. Depleted uranium differs from natural uranium in the balance of isotopes it contains. It is the byproduct of uranium enrichment for use in nuclear reactors or nuclear weapons and is valued for its very high density. Although less radioactive than natural uranium, depleted uranium is just as toxic and poses a threat to people.
In the new study, the researchers found that free-living and plant symbiotic (mycorrhizal) fungi can colonize depleted-uranium surfaces and transform the metal into uranyl phosphate minerals.
While they probably still pose some threat, he said, "The fungal-produced minerals are capable of long-term uranium retention, so this may help prevent uptake of uranium by plants, animals, and microbes. It might also prevent the spent uranium from leaching out from the soil."
Gadd said that a combination of environmental and biological factors is involved in the process. First, the unstable uranium metal gets coated with a layer of oxides. Moisture in the environment also "corrodes" the depleted uranium, encouraging fungal colonization and growth. While the fungi grow, they produce acidic substances, which corrode the depleted uranium even further. Some of the substances produced include organic acids that convert the uranium into a form that the fungi can take up or that can interact with other compounds. Ultimately, he said, the interaction of soluble forms of uranium with phosphate leads to the formation of the new uranium minerals that get deposited around the fungal biomass.
"We have shown for the first time that fungi can transform metallic uranium into minerals, which are capable of long-term uranium retention," the researchers concluded. "This phenomenon could be relevant to the future development of various remediation and revegetation techniques for uranium-polluted soils."
The researchers include Marina Fomina of University of Dundee in Dundee, Scotland; John M. Charnock of Synchrotron Radiation Source (SRS) Daresbury Laboratory in Daresbury, Warrington, Cheshire; Stephen Hillier of Macaulay Institute in Craigiebuckler, Aberdeen, Scotland; Rebeca Alvarez and Francis Livens of University of Manchester in Manchester, UK; and Geoffrey M. Gadd of University of Dundee in Dundee, Scotland.
This work was financially supported by the MOD/NERC DU Programme (Grant NE/C506799/1), CCLRC Daresbury SRS (SRS beamtime allocation 45100), and the Scottish Executive Environmental and Rural Affairs Department (SEERAD).
Journal reference: Fomina et al.: "Role of fungi in the biogeochemical fate of depleted uranium." Publishing in Current Biology 18, R375 --R377, May 6, 2008.
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