capitulum secundum, de generatione mineralium
dicamus ergo de generatione mineralium: dixerunt autem quidam quod natura mineralium omnium est argentu vivum cum sulphure, & dixerunt quod ex quo sive radix ipsorum mineralium est argentum vivum cum sulphure.
Tuesday, November 1, 2011
Wednesday, August 25, 2010
http://docsouth.unc.edu/imls/lecontesalt/leconte.html
"
Gunpowder is a mixture of saltpetre (potassium nitrate), charcoal and sulphur. The most critical ingredient is the saltpetre, says Smith, not least because it is by far the largest single constituent. By 1801, saltpetre was being supplied from natural nitrate deposits in India and south-east Asia. But from the mid-14th century until the 1620s — at least 15 years after the plot to blow up parliament — saltpetre was still made in the traditional medieval way, from manure.
"
Blast from the past. By: Hamer, Mick, New Scientist, 02624079, 11/5/2005, Vol. 188, Issue 2524
"
Gunpowder is a mixture of saltpetre (potassium nitrate), charcoal and sulphur. The most critical ingredient is the saltpetre, says Smith, not least because it is by far the largest single constituent. By 1801, saltpetre was being supplied from natural nitrate deposits in India and south-east Asia. But from the mid-14th century until the 1620s — at least 15 years after the plot to blow up parliament — saltpetre was still made in the traditional medieval way, from manure.
"
Blast from the past. By: Hamer, Mick, New Scientist, 02624079, 11/5/2005, Vol. 188, Issue 2524
Thursday, August 5, 2010
Sunday, January 31, 2010
The Shocking Truth About Running Shoes
The Shocking Truth About Running Shoes
By Gisela Telis
ScienceNOW Daily News
http://sciencenow.sciencemag.org
27 January 2010
Haile Gebrselassie, the world's fastest marathoner, once said of his early career, "When I wore shoes, it was difficult." A new study reveals why: Humans run differently in bare feet. Researchers have discovered that sneakers and other sports shoes alter our natural gait, which normally protects us from the impact of running. The finding offers new insight on how early humans ran and raises concerns that sports shoes may promote more injuries than they prevent.
About 2 million years ago, the ancestors of modern humans evolved the physiological "equipment" for running--long legs, large buttocks, and springy structures in the feet, among other features. Athletic shoes weren't invented until the early 1900s, and it wasn't until the 1970s that they found widespread popularity. So how did humans manage to run comfortably before the invention of purpose-built footwear?
Daniel Lieberman, a human evolutionary biologist at Harvard University--and an avid runner--decided to find out. He and colleagues looked at more than 200 shod and unshod runners in the United States and the Rift Valley Province of Kenya, which is known for its great endurance runners. The volunteers represented a spectrum of shoe experience, including adults who had grown up wearing shoes, those who had grown up running shoeless but who now wore shoes, and those who had never worn shoes at all. Lieberman's team arranged a trial in which each group ran shod (either in ASICS GEL-Cumulus 10s or in their own shoes) and bare and measured their running gait and the impact on their bodies.
The researchers noticed a difference right away. Whereas shod runners tended to land on the heel of the foot, barefoot runners landed on the ball of the foot or with a flat foot. The unshod runners' style causes more flex in the foot's springlike arch, ankle, and knee and engages more foot and calf muscles, blunting the impact on the body and making for a more comfortable "ride." As their feet collide with the ground--in this case, a running track--barefoot runners experience a shock of only 0.5 to 0.7 times their body weight, whereas shod heel strikers experience 1.5 to two times their body weight--a threefold to fourfold difference.
"I always assumed it was painful and crazy to run barefoot," says a surprised Lieberman. Instead, the findings--published tomorrow in Nature--suggest that going barefoot can reduce the likelihood of pain and damage, because many running injuries, like shin splints and plantar fasciitis, are stress- and impact-induced.
"This is an excellent study," says Dennis Bramble, an evolutionary morphologist at the University of Utah in Salt Lake City. "Heel strikes don't allow you to use these really nifty springs that are unique to human beings, so we're being less efficient than we could be," he says. "It confirms what we should have known all along: We're built to run barefoot."
That confirmation will stoke an ongoing debate. As a glance at this month's Runner's World magazine and a recent book on shoeless running called Born to Run attest, barefoot running has gained a small but devoted following in the past decade, prompting controversy in the running community over whether it is best to run shod or unshod.
So should sporty types shed their shoes and jump on the barefooted bandwagon? "Not at all," says Lieberman. "Shoes are comfortable, and they protect the foot" from glass, asphalt, and other harsh realities of urban running, he notes. Instead, Lieberman (who has since taken up occasional barefoot running himself) recommends a gradual transition for the bare-curious, one that allows the feet and calves to strengthen slowly and avoid injury.
By Gisela Telis
ScienceNOW Daily News
http://sciencenow.sciencemag.org
27 January 2010
Haile Gebrselassie, the world's fastest marathoner, once said of his early career, "When I wore shoes, it was difficult." A new study reveals why: Humans run differently in bare feet. Researchers have discovered that sneakers and other sports shoes alter our natural gait, which normally protects us from the impact of running. The finding offers new insight on how early humans ran and raises concerns that sports shoes may promote more injuries than they prevent.
About 2 million years ago, the ancestors of modern humans evolved the physiological "equipment" for running--long legs, large buttocks, and springy structures in the feet, among other features. Athletic shoes weren't invented until the early 1900s, and it wasn't until the 1970s that they found widespread popularity. So how did humans manage to run comfortably before the invention of purpose-built footwear?
Daniel Lieberman, a human evolutionary biologist at Harvard University--and an avid runner--decided to find out. He and colleagues looked at more than 200 shod and unshod runners in the United States and the Rift Valley Province of Kenya, which is known for its great endurance runners. The volunteers represented a spectrum of shoe experience, including adults who had grown up wearing shoes, those who had grown up running shoeless but who now wore shoes, and those who had never worn shoes at all. Lieberman's team arranged a trial in which each group ran shod (either in ASICS GEL-Cumulus 10s or in their own shoes) and bare and measured their running gait and the impact on their bodies.
The researchers noticed a difference right away. Whereas shod runners tended to land on the heel of the foot, barefoot runners landed on the ball of the foot or with a flat foot. The unshod runners' style causes more flex in the foot's springlike arch, ankle, and knee and engages more foot and calf muscles, blunting the impact on the body and making for a more comfortable "ride." As their feet collide with the ground--in this case, a running track--barefoot runners experience a shock of only 0.5 to 0.7 times their body weight, whereas shod heel strikers experience 1.5 to two times their body weight--a threefold to fourfold difference.
"I always assumed it was painful and crazy to run barefoot," says a surprised Lieberman. Instead, the findings--published tomorrow in Nature--suggest that going barefoot can reduce the likelihood of pain and damage, because many running injuries, like shin splints and plantar fasciitis, are stress- and impact-induced.
"This is an excellent study," says Dennis Bramble, an evolutionary morphologist at the University of Utah in Salt Lake City. "Heel strikes don't allow you to use these really nifty springs that are unique to human beings, so we're being less efficient than we could be," he says. "It confirms what we should have known all along: We're built to run barefoot."
That confirmation will stoke an ongoing debate. As a glance at this month's Runner's World magazine and a recent book on shoeless running called Born to Run attest, barefoot running has gained a small but devoted following in the past decade, prompting controversy in the running community over whether it is best to run shod or unshod.
So should sporty types shed their shoes and jump on the barefooted bandwagon? "Not at all," says Lieberman. "Shoes are comfortable, and they protect the foot" from glass, asphalt, and other harsh realities of urban running, he notes. Instead, Lieberman (who has since taken up occasional barefoot running himself) recommends a gradual transition for the bare-curious, one that allows the feet and calves to strengthen slowly and avoid injury.
Thursday, December 17, 2009
नोट्स ओं senescence
Cell death and organ development in plants
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Author(s): Rogers HJ
Source: CURRENT TOPICS IN DEVELOPMENTAL BIOLOGY, VOL 71 Book Series: CURRENT TOPICS IN DEVELOPMENTAL BIOLOGY Volume: 71 Pages: 225-+ Published: 2005
Times Cited: 19 References: 167 Citation MapCitation Map
Abstract: Programmed cell death (PCD) is an important feature of plant development; however, the mechanisms responsible for its regulation in plants are far less well understood than those operating in animals. In this review data from a wide variety of plant PCD systems is analyzed to compare what is known about the underlying mechanisms. Although senescence is clearly an important part of plant development, only what is known about PCD during senescence is dealt with here. In each PCD system the extracellular and intracellular signals triggering PCD are considered and both cytological and molecular data are discussed to determine whether a unique model for plant PCD can be derived. In the majority of cases reviewed, PCD is accompanied by the formation of a large vacuole, which ruptures to release hydrolytic enzymes that degrade the cell contents, although this model is clearly not universal. DNA degradation and the activation of proteases is also common to most plant PCD systems, where they have been studied; however, breakdown of DNA into nucleosomal units (DNA laddering) is not observed in all systems. Caspase-like activity has also been reported in several systems, but the extent to which it is a necessary feature of all plant PCD has not yet been established. The trigger for tonoplast rupture is not fully understood, although active oxygen species (AOS) have been implicated in several systems. In. two systems, self incompatibility and tapetal breakdown as a result of cytoplasmic male sterility, there is convincing evidence for the involvement of mitochondria including release of cytochrome c. However, in other systems, the role of the mitochondrion is not clear-cut. How cells surrounding the cell undergoing PCD protect themselves against death is also discussed as well as whether there is a link between the eventual fate of the cell corpse and the mechanism of its death. (c) 2005, Elsevier Inc.
Document Type: Review
Language: English
KeyWords Plus: TRACHEARY-ELEMENT DIFFERENTIATION; CASTOR BEAN ENDOSPERM; SENESCENCE-ASSOCIATED GENES; CYTOPLASMIC MALE-STERILITY; CYSTEINE PROTEASE GENE; WHEAT ALEURONE CELLS; ZEA-MAYS L.; LEAF SENESCENCE; AERENCHYMA FORMATION; BARLEY ALEURONE
Reprint Address: Rogers, HJ (reprint author), Cardiff Univ, Sch Biosci, Cardiff CF10 3TL, Wales
Addresses:
1. Cardiff Univ, Sch Biosci, Cardiff CF10 3TL, Wales
Publisher: ELSEVIER ACADEMIC PRESS INC, 525 B STREET, SUITE 1900, SAN DIEGO, CA 92101-4495 USA
Subject Category: Developmental Biology
IDS Number: BDI97
ISSN: 0070-2153
DOI: 10.1016/S0070-2153(05)71007-3
The molecular and genetic control of leaf senescence and longevity in Arabidopsis
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Author(s): Lim PO, Nam HG
Source: CURRENT TOPICS IN DEVELOPMENTAL BIOLOGY, VOL 67 Book Series: CURRENT TOPICS IN DEVELOPMENTAL BIOLOGY Volume: 67 Pages: 49-83 Published: 2005
Times Cited: 18 References: 111 Citation MapCitation Map
Abstract: The life of a leaf initiated from a leaf primordium ends with senescence, the final step of leaf development. Leaf senescence is a developmentally programmed degeneration process that is controlled by multiple developmental and environmental signals. It is a highly regulated and complex process that involves orderly, sequential changes in cellular physiology, biochemistry, and gene expression. Elucidating molecular mechanisms underlying such a complex, yet delicate process of leaf senescence is a challenging and important biological task. For the past decade, impressive progress has been achieved on the molecular processes of leaf senescence through identification of genes that show enhanced expression during senescence. In addition, Arabidopsis has been established as a model plant for genetic analysis of leaf senescence. The progress on the characterization of genetic mutants of leaf senescence in Arabidopsis has firmly shown that leaf senescence is a genetically controlled developmental phenomenon involving numerous regulatory elements. Especially, employment of global expression analysis as well as genomic resources in Arabidopsis has been very fruitful in revealing the molecular genetic nature and mechanisms underlying leaf senescence. This progress, including molecular characterization of some of the genetic regulatory elements, are revealing that senescence is composed of a complex regulatory network. In this review, we will present current understanding of the molecular genetic mechanisms by which leaf senescence is regulated and processed, focusing mostly on the regulatory factors of senescence in Arabidopsis. We also present a potential biotechnological implication of leaf senescence studies on the improvement of important agronomic traits such as crop yield and post-harvest shelf life. We further provide future research prospects to better understand the complex regulatory network of senescence. (c) 2005, Elsevier Inc.
Document Type: Review
Language: English
KeyWords Plus: END RULE PATHWAY; CAENORHABDITIS-ELEGANS; PROTEIN-DEGRADATION; PLANT SENESCENCE; PATHOGEN-DEFENSE; PHOSPHOLIPASE-D; MESSENGER-RNAS; TOMATO PLANTS; JASMONIC ACID; LARGE SUBUNIT
Reprint Address: Lim, PO (reprint author), Cheju Natl Univ, Dept Sci Educ, Cheju 690756, South Korea
Addresses:
1. Pohang Univ Sci & Technol, Natl Res Lab Plant Mol Genet, Div Mol & Life Sci, Pohang 790784, Kyungbuk South Korea
Publisher: ELSEVIER ACADEMIC PRESS INC, 525 B STREET, SUITE 1900, SAN DIEGO, CA 92101-4495 USA
Subject Category: Developmental Biology
IDS Number: BCM26
ISSN: 0070-2153
DOI: 10.1016/S0070-2153(04)67002-5
The molecular analysis of leaf senescence - a genomics approach
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Author(s): Buchanan-Wollaston V, Earl S, Harrison E, Mathas E, Navabpour S, Page T, Pink D
Source: PLANT BIOTECHNOLOGY JOURNAL Volume: 1 Issue: 1 Pages: 3-22 Published: JAN 2003
Times Cited: 155 References: 140 Citation MapCitation Map
Abstract: Senescence in green plants is a complex and highly regulated process that occurs as part of plant development or can be prematurely induced by stress. In the last decade, the main focus of research has been on the identification of senescence mutants, as well as on genes that show enhanced expression during senescence. Analysis of these is beginning to expand our understanding of the processes by which senescence functions. Recent rapid advances in genomics resources, especially for the model plant species Arabidopsis, are providing scientists with a dazzling array of tools for the identification and functional analysis of the genes and pathways involved in senescence. In this review, we present the current understanding of the mechanisms by which plants control senescence and the processes that are involved.
Document Type: Review
Language: English
Author Keywords: Arabidopsis; cell death; post-harvest; senescence; signalling pathways; stress
KeyWords Plus: PROGRAMMED CELL-DEATH; CYTOSOLIC GLUTAMINE-SYNTHETASE; PATHOGENESIS-RELATED PROTEINS; SENESCING ARABIDOPSIS LEAVES; ATP-DEPENDENT PROTEASE; DEFENSE-RELATED GENES; STAY-GREEN; DIFFERENTIAL EXPRESSION; FESTUCA-PRATENSIS; PLANT SENESCENCE
Reprint Address: Buchanan-Wollaston, V (reprint author), Hort Res Int, Prod Qual Team, Wellesbourne CV35 9EF, Warwick England
Addresses:
1. Hort Res Int, Prod Qual Team, Wellesbourne CV35 9EF, Warwick England
E-mail Addresses: vicky.b-wollaston@hri.ac.uk
Publisher: BLACKWELL PUBLISHING LTD, 9600 GARSINGTON RD, OXFORD OX4 2DG, OXON, ENGLAND
Subject Category: Biotechnology & Applied Microbiology; Plant Sciences
IDS Number: 774QE
ISSN: 1467-7644
F-box proteins in flowering plants
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Author(s): Wang HY, Huang J, Lai Z, Xue YB
Source: CHINESE SCIENCE BULLETIN Volume: 47 Issue: 18 Pages: 1497-1501 Published: SEP 2002
Times Cited: 1 References: 45 Citation MapCitation Map
Abstract: In eukaryotes, the ubiquitin-mediated protein degradation pathway has been shown to control several key biological processes such as cell division, development, metabolism and immune response. F-box proteins, as a part of SCF (Skp1-Cullin (or Cdc53)-F-box) complex, functioned by interacting with substrate proteins, leading to their subsequent degradation by the 26S proteasome. To date, several F-box proteins identified in Arabidopsis and Antirrhinum have been shown to play important roles in auxin signal transduction, floral organ formation, flowering and leaf senescence. Arabidopsis genome sequence analysis revealed that it encodes over 1000 predicted F-box proteins accounting for about 5% of total predicted proteins. These results indicate that the ubiquitin-mediated protein degradation involving the F-box proteins is an important mechanism controlling plant gene expression. Here, we review the known F-box proteins and their functions in flowering plants.
Document Type: Review
Language: English
Author Keywords: SCF complex; F-box protein; proteolysis; auxin signal transduction
KeyWords Plus: UBIQUITIN-DEPENDENT PROTEOLYSIS; AUXIN RESPONSE; CELL-CYCLE; SACCHAROMYCES-CEREVISIAE; ARABIDOPSIS-THALIANA; AUX/IAA PROTEINS; COP9 SIGNALOSOME; LIGASE COMPLEX; GENE; DEGRADATION
Reprint Address: Xue, YB (reprint author), Chinese Acad Sci, Inst Genet & Dev Biol, Beijing 100080, Peoples R China
Addresses:
1. Chinese Acad Sci, Inst Genet & Dev Biol, Beijing 100080, Peoples R China
E-mail Addresses: ybxue@genetics.ac.cn
Publisher: SCIENCE CHINA PRESS, 16 DONGHUANGCHENGGEN NORTH ST, BEIJING 100717, PEOPLES R CHINA
Subject Category: Multidisciplinary Sciences
IDS Number: 595TD
ISSN: 1001-6538
Current molecular understanding of the genetically programmed process of leaf senescence
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Author(s): Chandlee JM
Source: PHYSIOLOGIA PLANTARUM Volume: 113 Issue: 1 Pages: 1-8 Published: SEP 2001
Times Cited: 33 References: 47 Citation MapCitation Map
Abstract: Natural leaf senescence proceeds through an orderly program of events referred to, generally, as the 'senescence syndrome'. Leaf senescence consists of primarily, but not exclusively, a set of degradative and remobilization activities that salvage valuable nutrients by reallocation to the seeds or other viable parts of the plant. The program requires changes in gene expression and eventually culminates in death of the leaf or whole plant. Leaf/whole plant senescence has now been scrutinized extensively using molecular genetic approaches and a clearer picture of the events that comprise the developmental program is beginning to emerge. However, while understandings of the phenomenological aspects of the program have become apparent, the mechanistic aspects, particularly with regard to the processes required for induction and regulation of the program, are still far from clear. Molecular evidence suggests the process is complex in terms of the wide array of genes and activities expressed, and in terms of the overall regulation of progression of the events of the syndrome. This article attempts to review our current understanding of leaf senescence and includes a brief discussion of aspects of the process that require clarification if we are to more fully understand this complex developmental program.
Document Type: Review
Language: English
KeyWords Plus: GLUTAMINE-SYNTHETASE GENES; ARABIDOPSIS-THALIANA; BRASSICA-NAPUS; DIFFERENTIAL EXPRESSION; STAY-GREEN; TRANSGENIC PLANTS; TOMATO PLANTS; IDENTIFICATION; ETHYLENE; PROTEINS
Reprint Address: Chandlee, JM (reprint author), Univ Rhode Isl, Dept BIochem Microbiol & Mol Genet, Morrill Hall, Kingston, RI 02881 USA
Addresses:
1. Univ Rhode Isl, Dept BIochem Microbiol & Mol Genet, Kingston, RI 02881 USA
Publisher: MUNKSGAARD INT PUBL LTD, 35 NORRE SOGADE, PO BOX 2148, DK-1016 COPENHAGEN, DENMARK
Subject Category: Plant Sciences
IDS Number: 467TZ
ISSN: 0031-9317
Plant programmed cell death: A common way to die
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Author(s): Danon A, Delorme V, Mailhac N, Gallois P
Source: PLANT PHYSIOLOGY AND BIOCHEMISTRY Volume: 38 Issue: 9 Pages: 647-655 Published: SEP 2000
Times Cited: 91 References: 62 Citation MapCitation Map
Abstract: In the last few years programmed cell death in plants inspired many studies in development and environmental stresses. Some of these studies showed that hallmarks of animal programmed cell death were found at cellular or molecular level in plant cells in different experimental systems. Additionally the effect of over-expression in plants of animal genes implicated in programmed cell death has been tested, and some plant homologues of these genes have been found. This suggests that, despite some differences, plants and animals could share at least some common components of a core mechanism used to carry out programmed cell death in eukaryotes. In this review, we will concentrate on the last findings that suggest similarity between plant programmed cell death and its better known counterpart in animals. (C) 2000 Editions scientifiques et medicales Elsevier SAS.
Document Type: Review
Language: English
Author Keywords: apoptosis; caspases; DNA ladder; necrosis; plants; programmed cell death; TUNEL
KeyWords Plus: POLY(ADP-RIBOSE) POLYMERASE; HYPERSENSITIVE RESPONSE; ARABIDOPSIS-THALIANA; BARLEY ALEURONE; CYTOCHROME-C; APOPTOSIS; DNA; SENESCENCE; CASPASES; TOBACCO
Reprint Address: Gallois, P (reprint author), Univ Perpignan, Lab Genome & Dev Plantes, CNRS, UMR 5096, 52 Ave Villeneuve, F-66860 Perpignan, France
Addresses:
1. Univ Perpignan, Lab Genome & Dev Plantes, CNRS, UMR 5096, F-66860 Perpignan, France
Publisher: GAUTHIER-VILLARS/EDITIONS ELSEVIER, 23 RUE LINOIS, 75015 PARIS, FRANCE
Subject Category: Plant Sciences
IDS Number: 364CY
ISSN: 0981-9428
Programmed cell death during plant growth and development
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Author(s): Beers EP
Source: CELL DEATH AND DIFFERENTIATION Volume: 4 Issue: 8 Pages: 649-661 Published: DEC 1997
Times Cited: 79 References: 158 Citation MapCitation Map
Abstract: This review describes programmed cell death as it signifies the terminal differentiation of cells in anthers, xylem, the suspensor and senescing leaves and petals. Also described are cell suicide programs initiated by stress (e.g., hypoxia-induced aerenchyma formation) and those that depend on communication between neighboring cells, as observed for incompatible pollen tubes, the suspensor and synergids in some species. Although certain elements of apoptosis are detectable during some plant programmed cell death processes, the participation of autolytic and perhaps autophagic mechanisms of cell killing during aerenchyma formation, tracheary element differentiation, suspensor degeneration and senescence support the conclusion that nonapoptotic programmed cell death pathways are essential to normal plant growth and development. Heterophagic elimination of dead cells, a prominent feature of animal apoptosis, is not evident in plants. Rather autolysis and autophagy appear to govern the elimination of cells during plant cell suicide.
Document Type: Review
Language: English
Author Keywords: programmed cell death; plants; apoptosis; protease
KeyWords Plus: POLLEN-TUBE DEVELOPMENT; LEAF SENESCENCE; ARABIDOPSIS-THALIANA; SEX DETERMINATION; PEA-CHLOROPLASTS; PITH AUTOLYSIS; ZINNIA-ELEGANS; RIBULOSE-1,5-BISPHOSPHATE CARBOXYLASE; POLY(ADP-RIBOSE) POLYMERASE; CAENORHABDITIS-ELEGANS
Reprint Address: Beers, EP (reprint author), VIRGINIA POLYTECH INST & STATE UNIV, DEPT HORT, BLACKSBURG, VA 24061 USA
Publisher: STOCKTON PRESS, HOUNDMILLS, BASINGSTOKE, HAMPSHIRE, ENGLAND RG21 6XS
Subject Category: Biochemistry & Molecular Biology; Cell Biology
IDS Number: YJ306
ISSN: 1350-9047
Programmed senescence of plant organs
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Author(s): Hadfield KA, Bennett AB
Source: CELL DEATH AND DIFFERENTIATION Volume: 4 Issue: 8 Pages: 662-670 Published: DEC 1997
Times Cited: 36 References: 139 Citation MapCitation Map
Abstract: The senescence of plant organs associated with reproductive development has been studied extensively during the past century, and it has long been recognized that th is type of death is internally programmed. The regulation of organ senescence as well as its biochemical and genetic determinants has been an historically rich area of research. Certain plant hormones have been implicated as regulators or modulators of organ senescence and many of the biochemical pathways associated with the senescence syndrome have been elucidated. The genetic basis of organ senescence has also been well established by the identification of mutations that impair the senescence program and recently, transgenic plants have been used to critically determine the role of specific enzymes and hormonal signals in mediating programmed senescence of plant organs, Here, we review the current understanding of the processes that regulate leaf, flower and fruit senescence, emphasizing the rate that programmed organ senescence plays in the adaptive fitness of plants.
Document Type: Review
Language: English
Author Keywords: survivorship; fruit ripening; organ senescence
KeyWords Plus: ENCODING 1-AMINOCYCLOPROPANE-1-CARBOXYLATE SYNTHASE; TOMATO FRUIT POLYGALACTURONASE; ETHYLENE-INDUCIBLE EXPRESSION; DELAYED LEAF SENESCENCE; CARNATION FLOWER PETALS; MESSENGER-RNA LEVELS; GENE-EXPRESSION; MOLECULAR-CLONING; PROTEIN-SYNTHESIS; AVOCADO FRUIT
Addresses:
1. UNIV CALIF DAVIS, DEPT VEGETABLE CROPS, MANN LAB, DAVIS, CA 95616 USA
Publisher: STOCKTON PRESS, HOUNDMILLS, BASINGSTOKE, HAMPSHIRE, ENGLAND RG21 6XS
Subject Category: Biochemistry & Molecular Biology; Cell Biology
IDS Number: YJ306
ISSN: 1350-9047
GENE-EXPRESSION DURING LEAF SENESCENCE
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Author(s): SMART CM
Source: NEW PHYTOLOGIST Volume: 126 Issue: 3 Pages: 419-448 Published: MAR 1994
Times Cited: 366 References: 297 Citation MapCitation Map
Abstract: Leaf senescence is a highly-controlled sequence of events comprising the final stage of development. Cells remain viable during the process and new gene expression is required. There is some similarity between senescence in plants and programmed cell death in animals. In this review, different classes of senescence-related genes are defined and progress towards isolating such genes is reported. A range of internal and external factors which appear to cause leaf senescence is considered and various models for the mechanism of senescence initiation are described. The current understanding of senescence at the organelle and molecular levels is presented. Finally, some ideas are mooted as to why senescence occurs and why it should be studied further.
Document Type: Review
Language: English
Author Keywords: LEAF SENESCENCE; PROGRAMMED CELL DEATH; GENES; PLANT GROWTH REGULATORS; ORGANELLES; MOLECULES
KeyWords Plus: NON-YELLOWING MUTANT; SENESCING BARLEY LEAVES; TRITICUM-AESTIVUM L; CYTOSOLIC GLUTAMINE-SYNTHETASE; REJUVENATED SOYBEAN COTYLEDONS; TRANSLATABLE MESSENGER-RNAS; PEPTIDE-HYDROLASE ACTIVITY; DARK-INDUCED SENESCENCE; FESTUCA-PRATENSIS HUDS; PROGRAMMED CELL-DEATH
Reprint Address: SMART, CM (reprint author), AFRC, INST GRASSLAND & ENVIRONM RES, DEPT CELL BIOL, PLAS GOGERDDAN, ABERYSTWYTH SY23 3EB, DYFED WALES
Publisher: CAMBRIDGE UNIV PRESS, 40 WEST 20TH STREET, NEW YORK, NY 10011-4211
Subject Category: Plant Sciences
IDS Number: NG798
ISSN: 0028-646X
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Author(s): Rogers HJ
Source: CURRENT TOPICS IN DEVELOPMENTAL BIOLOGY, VOL 71 Book Series: CURRENT TOPICS IN DEVELOPMENTAL BIOLOGY Volume: 71 Pages: 225-+ Published: 2005
Times Cited: 19 References: 167 Citation MapCitation Map
Abstract: Programmed cell death (PCD) is an important feature of plant development; however, the mechanisms responsible for its regulation in plants are far less well understood than those operating in animals. In this review data from a wide variety of plant PCD systems is analyzed to compare what is known about the underlying mechanisms. Although senescence is clearly an important part of plant development, only what is known about PCD during senescence is dealt with here. In each PCD system the extracellular and intracellular signals triggering PCD are considered and both cytological and molecular data are discussed to determine whether a unique model for plant PCD can be derived. In the majority of cases reviewed, PCD is accompanied by the formation of a large vacuole, which ruptures to release hydrolytic enzymes that degrade the cell contents, although this model is clearly not universal. DNA degradation and the activation of proteases is also common to most plant PCD systems, where they have been studied; however, breakdown of DNA into nucleosomal units (DNA laddering) is not observed in all systems. Caspase-like activity has also been reported in several systems, but the extent to which it is a necessary feature of all plant PCD has not yet been established. The trigger for tonoplast rupture is not fully understood, although active oxygen species (AOS) have been implicated in several systems. In. two systems, self incompatibility and tapetal breakdown as a result of cytoplasmic male sterility, there is convincing evidence for the involvement of mitochondria including release of cytochrome c. However, in other systems, the role of the mitochondrion is not clear-cut. How cells surrounding the cell undergoing PCD protect themselves against death is also discussed as well as whether there is a link between the eventual fate of the cell corpse and the mechanism of its death. (c) 2005, Elsevier Inc.
Document Type: Review
Language: English
KeyWords Plus: TRACHEARY-ELEMENT DIFFERENTIATION; CASTOR BEAN ENDOSPERM; SENESCENCE-ASSOCIATED GENES; CYTOPLASMIC MALE-STERILITY; CYSTEINE PROTEASE GENE; WHEAT ALEURONE CELLS; ZEA-MAYS L.; LEAF SENESCENCE; AERENCHYMA FORMATION; BARLEY ALEURONE
Reprint Address: Rogers, HJ (reprint author), Cardiff Univ, Sch Biosci, Cardiff CF10 3TL, Wales
Addresses:
1. Cardiff Univ, Sch Biosci, Cardiff CF10 3TL, Wales
Publisher: ELSEVIER ACADEMIC PRESS INC, 525 B STREET, SUITE 1900, SAN DIEGO, CA 92101-4495 USA
Subject Category: Developmental Biology
IDS Number: BDI97
ISSN: 0070-2153
DOI: 10.1016/S0070-2153(05)71007-3
The molecular and genetic control of leaf senescence and longevity in Arabidopsis
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Author(s): Lim PO, Nam HG
Source: CURRENT TOPICS IN DEVELOPMENTAL BIOLOGY, VOL 67 Book Series: CURRENT TOPICS IN DEVELOPMENTAL BIOLOGY Volume: 67 Pages: 49-83 Published: 2005
Times Cited: 18 References: 111 Citation MapCitation Map
Abstract: The life of a leaf initiated from a leaf primordium ends with senescence, the final step of leaf development. Leaf senescence is a developmentally programmed degeneration process that is controlled by multiple developmental and environmental signals. It is a highly regulated and complex process that involves orderly, sequential changes in cellular physiology, biochemistry, and gene expression. Elucidating molecular mechanisms underlying such a complex, yet delicate process of leaf senescence is a challenging and important biological task. For the past decade, impressive progress has been achieved on the molecular processes of leaf senescence through identification of genes that show enhanced expression during senescence. In addition, Arabidopsis has been established as a model plant for genetic analysis of leaf senescence. The progress on the characterization of genetic mutants of leaf senescence in Arabidopsis has firmly shown that leaf senescence is a genetically controlled developmental phenomenon involving numerous regulatory elements. Especially, employment of global expression analysis as well as genomic resources in Arabidopsis has been very fruitful in revealing the molecular genetic nature and mechanisms underlying leaf senescence. This progress, including molecular characterization of some of the genetic regulatory elements, are revealing that senescence is composed of a complex regulatory network. In this review, we will present current understanding of the molecular genetic mechanisms by which leaf senescence is regulated and processed, focusing mostly on the regulatory factors of senescence in Arabidopsis. We also present a potential biotechnological implication of leaf senescence studies on the improvement of important agronomic traits such as crop yield and post-harvest shelf life. We further provide future research prospects to better understand the complex regulatory network of senescence. (c) 2005, Elsevier Inc.
Document Type: Review
Language: English
KeyWords Plus: END RULE PATHWAY; CAENORHABDITIS-ELEGANS; PROTEIN-DEGRADATION; PLANT SENESCENCE; PATHOGEN-DEFENSE; PHOSPHOLIPASE-D; MESSENGER-RNAS; TOMATO PLANTS; JASMONIC ACID; LARGE SUBUNIT
Reprint Address: Lim, PO (reprint author), Cheju Natl Univ, Dept Sci Educ, Cheju 690756, South Korea
Addresses:
1. Pohang Univ Sci & Technol, Natl Res Lab Plant Mol Genet, Div Mol & Life Sci, Pohang 790784, Kyungbuk South Korea
Publisher: ELSEVIER ACADEMIC PRESS INC, 525 B STREET, SUITE 1900, SAN DIEGO, CA 92101-4495 USA
Subject Category: Developmental Biology
IDS Number: BCM26
ISSN: 0070-2153
DOI: 10.1016/S0070-2153(04)67002-5
The molecular analysis of leaf senescence - a genomics approach
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Author(s): Buchanan-Wollaston V, Earl S, Harrison E, Mathas E, Navabpour S, Page T, Pink D
Source: PLANT BIOTECHNOLOGY JOURNAL Volume: 1 Issue: 1 Pages: 3-22 Published: JAN 2003
Times Cited: 155 References: 140 Citation MapCitation Map
Abstract: Senescence in green plants is a complex and highly regulated process that occurs as part of plant development or can be prematurely induced by stress. In the last decade, the main focus of research has been on the identification of senescence mutants, as well as on genes that show enhanced expression during senescence. Analysis of these is beginning to expand our understanding of the processes by which senescence functions. Recent rapid advances in genomics resources, especially for the model plant species Arabidopsis, are providing scientists with a dazzling array of tools for the identification and functional analysis of the genes and pathways involved in senescence. In this review, we present the current understanding of the mechanisms by which plants control senescence and the processes that are involved.
Document Type: Review
Language: English
Author Keywords: Arabidopsis; cell death; post-harvest; senescence; signalling pathways; stress
KeyWords Plus: PROGRAMMED CELL-DEATH; CYTOSOLIC GLUTAMINE-SYNTHETASE; PATHOGENESIS-RELATED PROTEINS; SENESCING ARABIDOPSIS LEAVES; ATP-DEPENDENT PROTEASE; DEFENSE-RELATED GENES; STAY-GREEN; DIFFERENTIAL EXPRESSION; FESTUCA-PRATENSIS; PLANT SENESCENCE
Reprint Address: Buchanan-Wollaston, V (reprint author), Hort Res Int, Prod Qual Team, Wellesbourne CV35 9EF, Warwick England
Addresses:
1. Hort Res Int, Prod Qual Team, Wellesbourne CV35 9EF, Warwick England
E-mail Addresses: vicky.b-wollaston@hri.ac.uk
Publisher: BLACKWELL PUBLISHING LTD, 9600 GARSINGTON RD, OXFORD OX4 2DG, OXON, ENGLAND
Subject Category: Biotechnology & Applied Microbiology; Plant Sciences
IDS Number: 774QE
ISSN: 1467-7644
F-box proteins in flowering plants
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Author(s): Wang HY, Huang J, Lai Z, Xue YB
Source: CHINESE SCIENCE BULLETIN Volume: 47 Issue: 18 Pages: 1497-1501 Published: SEP 2002
Times Cited: 1 References: 45 Citation MapCitation Map
Abstract: In eukaryotes, the ubiquitin-mediated protein degradation pathway has been shown to control several key biological processes such as cell division, development, metabolism and immune response. F-box proteins, as a part of SCF (Skp1-Cullin (or Cdc53)-F-box) complex, functioned by interacting with substrate proteins, leading to their subsequent degradation by the 26S proteasome. To date, several F-box proteins identified in Arabidopsis and Antirrhinum have been shown to play important roles in auxin signal transduction, floral organ formation, flowering and leaf senescence. Arabidopsis genome sequence analysis revealed that it encodes over 1000 predicted F-box proteins accounting for about 5% of total predicted proteins. These results indicate that the ubiquitin-mediated protein degradation involving the F-box proteins is an important mechanism controlling plant gene expression. Here, we review the known F-box proteins and their functions in flowering plants.
Document Type: Review
Language: English
Author Keywords: SCF complex; F-box protein; proteolysis; auxin signal transduction
KeyWords Plus: UBIQUITIN-DEPENDENT PROTEOLYSIS; AUXIN RESPONSE; CELL-CYCLE; SACCHAROMYCES-CEREVISIAE; ARABIDOPSIS-THALIANA; AUX/IAA PROTEINS; COP9 SIGNALOSOME; LIGASE COMPLEX; GENE; DEGRADATION
Reprint Address: Xue, YB (reprint author), Chinese Acad Sci, Inst Genet & Dev Biol, Beijing 100080, Peoples R China
Addresses:
1. Chinese Acad Sci, Inst Genet & Dev Biol, Beijing 100080, Peoples R China
E-mail Addresses: ybxue@genetics.ac.cn
Publisher: SCIENCE CHINA PRESS, 16 DONGHUANGCHENGGEN NORTH ST, BEIJING 100717, PEOPLES R CHINA
Subject Category: Multidisciplinary Sciences
IDS Number: 595TD
ISSN: 1001-6538
Current molecular understanding of the genetically programmed process of leaf senescence
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Author(s): Chandlee JM
Source: PHYSIOLOGIA PLANTARUM Volume: 113 Issue: 1 Pages: 1-8 Published: SEP 2001
Times Cited: 33 References: 47 Citation MapCitation Map
Abstract: Natural leaf senescence proceeds through an orderly program of events referred to, generally, as the 'senescence syndrome'. Leaf senescence consists of primarily, but not exclusively, a set of degradative and remobilization activities that salvage valuable nutrients by reallocation to the seeds or other viable parts of the plant. The program requires changes in gene expression and eventually culminates in death of the leaf or whole plant. Leaf/whole plant senescence has now been scrutinized extensively using molecular genetic approaches and a clearer picture of the events that comprise the developmental program is beginning to emerge. However, while understandings of the phenomenological aspects of the program have become apparent, the mechanistic aspects, particularly with regard to the processes required for induction and regulation of the program, are still far from clear. Molecular evidence suggests the process is complex in terms of the wide array of genes and activities expressed, and in terms of the overall regulation of progression of the events of the syndrome. This article attempts to review our current understanding of leaf senescence and includes a brief discussion of aspects of the process that require clarification if we are to more fully understand this complex developmental program.
Document Type: Review
Language: English
KeyWords Plus: GLUTAMINE-SYNTHETASE GENES; ARABIDOPSIS-THALIANA; BRASSICA-NAPUS; DIFFERENTIAL EXPRESSION; STAY-GREEN; TRANSGENIC PLANTS; TOMATO PLANTS; IDENTIFICATION; ETHYLENE; PROTEINS
Reprint Address: Chandlee, JM (reprint author), Univ Rhode Isl, Dept BIochem Microbiol & Mol Genet, Morrill Hall, Kingston, RI 02881 USA
Addresses:
1. Univ Rhode Isl, Dept BIochem Microbiol & Mol Genet, Kingston, RI 02881 USA
Publisher: MUNKSGAARD INT PUBL LTD, 35 NORRE SOGADE, PO BOX 2148, DK-1016 COPENHAGEN, DENMARK
Subject Category: Plant Sciences
IDS Number: 467TZ
ISSN: 0031-9317
Plant programmed cell death: A common way to die
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Author(s): Danon A, Delorme V, Mailhac N, Gallois P
Source: PLANT PHYSIOLOGY AND BIOCHEMISTRY Volume: 38 Issue: 9 Pages: 647-655 Published: SEP 2000
Times Cited: 91 References: 62 Citation MapCitation Map
Abstract: In the last few years programmed cell death in plants inspired many studies in development and environmental stresses. Some of these studies showed that hallmarks of animal programmed cell death were found at cellular or molecular level in plant cells in different experimental systems. Additionally the effect of over-expression in plants of animal genes implicated in programmed cell death has been tested, and some plant homologues of these genes have been found. This suggests that, despite some differences, plants and animals could share at least some common components of a core mechanism used to carry out programmed cell death in eukaryotes. In this review, we will concentrate on the last findings that suggest similarity between plant programmed cell death and its better known counterpart in animals. (C) 2000 Editions scientifiques et medicales Elsevier SAS.
Document Type: Review
Language: English
Author Keywords: apoptosis; caspases; DNA ladder; necrosis; plants; programmed cell death; TUNEL
KeyWords Plus: POLY(ADP-RIBOSE) POLYMERASE; HYPERSENSITIVE RESPONSE; ARABIDOPSIS-THALIANA; BARLEY ALEURONE; CYTOCHROME-C; APOPTOSIS; DNA; SENESCENCE; CASPASES; TOBACCO
Reprint Address: Gallois, P (reprint author), Univ Perpignan, Lab Genome & Dev Plantes, CNRS, UMR 5096, 52 Ave Villeneuve, F-66860 Perpignan, France
Addresses:
1. Univ Perpignan, Lab Genome & Dev Plantes, CNRS, UMR 5096, F-66860 Perpignan, France
Publisher: GAUTHIER-VILLARS/EDITIONS ELSEVIER, 23 RUE LINOIS, 75015 PARIS, FRANCE
Subject Category: Plant Sciences
IDS Number: 364CY
ISSN: 0981-9428
Programmed cell death during plant growth and development
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Author(s): Beers EP
Source: CELL DEATH AND DIFFERENTIATION Volume: 4 Issue: 8 Pages: 649-661 Published: DEC 1997
Times Cited: 79 References: 158 Citation MapCitation Map
Abstract: This review describes programmed cell death as it signifies the terminal differentiation of cells in anthers, xylem, the suspensor and senescing leaves and petals. Also described are cell suicide programs initiated by stress (e.g., hypoxia-induced aerenchyma formation) and those that depend on communication between neighboring cells, as observed for incompatible pollen tubes, the suspensor and synergids in some species. Although certain elements of apoptosis are detectable during some plant programmed cell death processes, the participation of autolytic and perhaps autophagic mechanisms of cell killing during aerenchyma formation, tracheary element differentiation, suspensor degeneration and senescence support the conclusion that nonapoptotic programmed cell death pathways are essential to normal plant growth and development. Heterophagic elimination of dead cells, a prominent feature of animal apoptosis, is not evident in plants. Rather autolysis and autophagy appear to govern the elimination of cells during plant cell suicide.
Document Type: Review
Language: English
Author Keywords: programmed cell death; plants; apoptosis; protease
KeyWords Plus: POLLEN-TUBE DEVELOPMENT; LEAF SENESCENCE; ARABIDOPSIS-THALIANA; SEX DETERMINATION; PEA-CHLOROPLASTS; PITH AUTOLYSIS; ZINNIA-ELEGANS; RIBULOSE-1,5-BISPHOSPHATE CARBOXYLASE; POLY(ADP-RIBOSE) POLYMERASE; CAENORHABDITIS-ELEGANS
Reprint Address: Beers, EP (reprint author), VIRGINIA POLYTECH INST & STATE UNIV, DEPT HORT, BLACKSBURG, VA 24061 USA
Publisher: STOCKTON PRESS, HOUNDMILLS, BASINGSTOKE, HAMPSHIRE, ENGLAND RG21 6XS
Subject Category: Biochemistry & Molecular Biology; Cell Biology
IDS Number: YJ306
ISSN: 1350-9047
Programmed senescence of plant organs
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Author(s): Hadfield KA, Bennett AB
Source: CELL DEATH AND DIFFERENTIATION Volume: 4 Issue: 8 Pages: 662-670 Published: DEC 1997
Times Cited: 36 References: 139 Citation MapCitation Map
Abstract: The senescence of plant organs associated with reproductive development has been studied extensively during the past century, and it has long been recognized that th is type of death is internally programmed. The regulation of organ senescence as well as its biochemical and genetic determinants has been an historically rich area of research. Certain plant hormones have been implicated as regulators or modulators of organ senescence and many of the biochemical pathways associated with the senescence syndrome have been elucidated. The genetic basis of organ senescence has also been well established by the identification of mutations that impair the senescence program and recently, transgenic plants have been used to critically determine the role of specific enzymes and hormonal signals in mediating programmed senescence of plant organs, Here, we review the current understanding of the processes that regulate leaf, flower and fruit senescence, emphasizing the rate that programmed organ senescence plays in the adaptive fitness of plants.
Document Type: Review
Language: English
Author Keywords: survivorship; fruit ripening; organ senescence
KeyWords Plus: ENCODING 1-AMINOCYCLOPROPANE-1-CARBOXYLATE SYNTHASE; TOMATO FRUIT POLYGALACTURONASE; ETHYLENE-INDUCIBLE EXPRESSION; DELAYED LEAF SENESCENCE; CARNATION FLOWER PETALS; MESSENGER-RNA LEVELS; GENE-EXPRESSION; MOLECULAR-CLONING; PROTEIN-SYNTHESIS; AVOCADO FRUIT
Addresses:
1. UNIV CALIF DAVIS, DEPT VEGETABLE CROPS, MANN LAB, DAVIS, CA 95616 USA
Publisher: STOCKTON PRESS, HOUNDMILLS, BASINGSTOKE, HAMPSHIRE, ENGLAND RG21 6XS
Subject Category: Biochemistry & Molecular Biology; Cell Biology
IDS Number: YJ306
ISSN: 1350-9047
GENE-EXPRESSION DURING LEAF SENESCENCE
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Author(s): SMART CM
Source: NEW PHYTOLOGIST Volume: 126 Issue: 3 Pages: 419-448 Published: MAR 1994
Times Cited: 366 References: 297 Citation MapCitation Map
Abstract: Leaf senescence is a highly-controlled sequence of events comprising the final stage of development. Cells remain viable during the process and new gene expression is required. There is some similarity between senescence in plants and programmed cell death in animals. In this review, different classes of senescence-related genes are defined and progress towards isolating such genes is reported. A range of internal and external factors which appear to cause leaf senescence is considered and various models for the mechanism of senescence initiation are described. The current understanding of senescence at the organelle and molecular levels is presented. Finally, some ideas are mooted as to why senescence occurs and why it should be studied further.
Document Type: Review
Language: English
Author Keywords: LEAF SENESCENCE; PROGRAMMED CELL DEATH; GENES; PLANT GROWTH REGULATORS; ORGANELLES; MOLECULES
KeyWords Plus: NON-YELLOWING MUTANT; SENESCING BARLEY LEAVES; TRITICUM-AESTIVUM L; CYTOSOLIC GLUTAMINE-SYNTHETASE; REJUVENATED SOYBEAN COTYLEDONS; TRANSLATABLE MESSENGER-RNAS; PEPTIDE-HYDROLASE ACTIVITY; DARK-INDUCED SENESCENCE; FESTUCA-PRATENSIS HUDS; PROGRAMMED CELL-DEATH
Reprint Address: SMART, CM (reprint author), AFRC, INST GRASSLAND & ENVIRONM RES, DEPT CELL BIOL, PLAS GOGERDDAN, ABERYSTWYTH SY23 3EB, DYFED WALES
Publisher: CAMBRIDGE UNIV PRESS, 40 WEST 20TH STREET, NEW YORK, NY 10011-4211
Subject Category: Plant Sciences
IDS Number: NG798
ISSN: 0028-646X
Wednesday, December 2, 2009
Seborrhoeic dermatitis
Collection of words for searching:
Seborrhoeic dermatitis
biotin, pyridoxine (vitamin B6) and riboflavin (vitamin B2)
yeast, Malassezia furfur
Seborrhoeic dermatitis
biotin, pyridoxine (vitamin B6) and riboflavin (vitamin B2)
yeast, Malassezia furfur
Thursday, November 26, 2009
salinity tolerance in cereals
Rajendran, K., Tester, M. & Roy, S.J. (2009) Quantifying the three main components of salinity tolerance in cereals. Plant, Cell & Environment 32, 237-249
from Naked Scientist:
http://www.thenakedscientists.com/HTML/content/interviews/interview/1239/
Chris - So how did you do that rather clever trick of making that gene only get turned on in those cells around these xylem vessels because that’s the breakthrough step, isn’t it really?
Mark - Yes, it is. There’s different ways you can do this. One is to try to discover little bits of DNA which will activate genes in specific parts of the plant. So that’s one way you can do it a very direct way. In the meantime, we’re using a model plant. It’s called Arabidopsis. It’s a silly little weed, but you can do lots of really nice molecular genetics with it. And what we did was throw into the genome of this little plant, this little weed, a little bit of DNA which allows us to turn on genes. But we threw it on in random in the genome, made thousands of these plants and then looked at the plants to find ones which had the right pattern of expression. So the initial generation of the plants was random and then we looked to find plants which had by fluke, this bit of DNA landing in a part of the genome that would activate that gene only in the inner half of the root.
Chris - Big question though, Mark must be a course, it’s one thing to do this in thale cress, the plant sciences fruit fly. But we don’t eat that. So what about things that we do eat? Could you put this same genetic combination into rice, into barley, wheat, and so on? The kinds of things we do rely on for food staples.
Mark - Absolutely, Chris. We have done this in rice and the results are looking very promising. We look like we’ve worked out how to reduce the sodium concentration. Well we have reduced the sodium concentration in the shoots of rice and we’re in the process of testing the effect of that on yield. The first experiments did improve yield, but we just want to again be fairly conservative rather than just shooting off the results rapidly. But it’s looking very promising. To turn the genes on in wheat and barley, maze, it’s actually quite difficult because these molecular genetic tricks that we’re able to use on Arabidopsis, we just simply can’t do it. We’re technically not able to do it in wheat and barley. So what we’re doing now is we’re having a program to discover the promoters that would help us turn this on, so going back to a very direct but slower way of manipulating an expression in wheat and barley. We actually have transgenic plants in the glasshouse at the moment for wheat and barley and we’re limited by bulking up the seed, and we’re just at that stage at the moment. So keep your fingers crossed for us and hopefully in the year’s time, we’ll be able to say if we’ve done it in the other crops as well.
from Naked Scientist:
http://www.thenakedscientists.com/HTML/content/interviews/interview/1239/
Chris - So how did you do that rather clever trick of making that gene only get turned on in those cells around these xylem vessels because that’s the breakthrough step, isn’t it really?
Mark - Yes, it is. There’s different ways you can do this. One is to try to discover little bits of DNA which will activate genes in specific parts of the plant. So that’s one way you can do it a very direct way. In the meantime, we’re using a model plant. It’s called Arabidopsis. It’s a silly little weed, but you can do lots of really nice molecular genetics with it. And what we did was throw into the genome of this little plant, this little weed, a little bit of DNA which allows us to turn on genes. But we threw it on in random in the genome, made thousands of these plants and then looked at the plants to find ones which had the right pattern of expression. So the initial generation of the plants was random and then we looked to find plants which had by fluke, this bit of DNA landing in a part of the genome that would activate that gene only in the inner half of the root.
Chris - Big question though, Mark must be a course, it’s one thing to do this in thale cress, the plant sciences fruit fly. But we don’t eat that. So what about things that we do eat? Could you put this same genetic combination into rice, into barley, wheat, and so on? The kinds of things we do rely on for food staples.
Mark - Absolutely, Chris. We have done this in rice and the results are looking very promising. We look like we’ve worked out how to reduce the sodium concentration. Well we have reduced the sodium concentration in the shoots of rice and we’re in the process of testing the effect of that on yield. The first experiments did improve yield, but we just want to again be fairly conservative rather than just shooting off the results rapidly. But it’s looking very promising. To turn the genes on in wheat and barley, maze, it’s actually quite difficult because these molecular genetic tricks that we’re able to use on Arabidopsis, we just simply can’t do it. We’re technically not able to do it in wheat and barley. So what we’re doing now is we’re having a program to discover the promoters that would help us turn this on, so going back to a very direct but slower way of manipulating an expression in wheat and barley. We actually have transgenic plants in the glasshouse at the moment for wheat and barley and we’re limited by bulking up the seed, and we’re just at that stage at the moment. So keep your fingers crossed for us and hopefully in the year’s time, we’ll be able to say if we’ve done it in the other crops as well.
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