- Email: [email protected]
Healing power of plants
News & Comment
releasing the plants into constant light. They used highly reproducible oligonucleotidebased arrays (GeneChip arrays) representing ~8200 different genes. More than 450 of these genes displayed circadian changes in steady-state mRNA levels. Many of the cycling genes identified in the experiment could be classified into functional groups based upon their known or predicted physiological roles. The functional clusters included genes involved in photosynthetic light harvesting, synthesis of protective phenolic compounds, lipid modification, carbon metabolism and partitioning, nitrogen and sulfur assimilation, cell elongation and flowering, and genes coding for informational photoreceptors such as phyB, cryptochromes and phototropin. Using a computational analysis of oscillating genes, the authors were able to identify a novel promoter element that confers circadian rhythmicity on expression, and the functional role of this conserved promoter motif was confirmed through mutational analysis.
TRENDS in Plant Science Vol.6 No.3 March 2001
What is the primary driving force for circadian clock evolution? Perhaps the main advantage that plants gain by putting gene expression under circadian regulation is the ability to anticipate diurnal changes in the environment, such as fluctuations of light, UV and temperature levels. Or perhaps the key function of the clock is to provide a temporal framework for internal coordination of physiological activities. ‘...this study has given us the first opportunity to listen for a full 48 h to an Arabidopsis gene-expression symphony.’ The fact that several photosynthetic genes, and genes involved in the synthesis of phenolic sunscreens and in chilling tolerance were found to be under circadian control is certainly consistent with the first hypothesis. In addition, the demonstration of circadian rhythmicity in the expression of genes involved in carbon partitioning and in the energy-intensive processes of nitrogen and sulfur assimilation is indeed consistent with
97
the idea that the clock plays a key role in maintaining internal balance and physiological harmony. In fact, for those interested in functional coordination in plants, reading the paper of Harmer et al.1 will evoke a similar sensation as listening to a philharmonic orchestra after attending rehearsals of individual players or sections. By simultaneously monitoring the circadian regulation of a few thousand genes, this study has given us the first opportunity to listen for a full 48 h to an Arabidopsis gene-expression symphony. The perspective afforded by studies such as this sets the stage to discover novel expression ‘sounds’, and to appreciate the role of each particular gene player in the broad context of plant physiological homeostasis and functional organization. 1 Harmer, S.L. et al. (2001) Orchestrated transcription of key pathways in Arabidopsis by the circadian clock. Science 290, 2110–2113
Carlos L. Ballaré [email protected]
In Brief
Healing power of plants Alzheimer’s, a degenerative brain disease, represents one of the cruellest blows associated with ageing. However, hope is at hand with reports that a compound, galantamine, found in bulbs of daffodil (Narcissus pseudonarcissus) can delay some of the symptoms of the illness [Br. Med. J. (2000) 321, 1–7]. Galantamine acts partly by stimulating nicotine-receptors in the brain, and partly by inhibiting acetylcholinesterase, thereby preserving the otherwise diminishing levels of acetylcholine. In this way, its action is similar to smoking tobacco, but without the harmful effects associated with this more infamous plant product. [Dobson, R. (2001) Daily Mail (UK) 5 September.] NC
It’s official: Brussels sprouts really are good for you Parents frequently experience problems getting children to ‘eat their greens’. Now a research review from a group at the University of Washington (USA) [Am. J. Clin. Nutr. (2000) 72, 1424–1435] provides even greater reason for parents to persist in feeding vegetables such as Brussels sprouts, cabbage and spinach to their offspring. That
work shows that the trace chemicals that give such food its bitter taste are often associated with cancer prevention and other health benefits. Unfortunately, in efforts to make these vegetables more palatable, the food industry has largely removed this bitterness, either chemically during processing or by breeding and selection. It is suggested that the Mediterranean practice of lightly seasoning with salt and a dash of olive oil would be a better way of coping with the unpleasant taste, and do more good. NC
Castor plants’ promising future Although castor has fallen out of popularity as a common crop, that might change in the future. Oil from castor beans contains hydroxy fatty acids and is essential for making high quality industrial lubricants. Castor’s two main problems are that the oil-rich seed contains powerful allergens and ricin, a toxin seven times more deadly than cobra venom. The genes crucial for both ricin and the allergens are known. Now, Thomas McKeon and Grace Chen, both at USDA-ARS (Albany, CA, USA) are the first in the world to produce genetically engineered castor plants. The first transgenic castor plants contained marker genes, but the group is planning to use anti-sense
technology to reduce the allergens and ricin toxin in castor. The world market for castor oil is lucrative at A$400 million per year. Photograph by Brian Prechtel, courtesy of ARS. (http://www.ars.usda.gov/ is/AR/archive/jan01/plant0101.htm) TS
Canada mines for marijuana The government of Canada has awarded a C$5.7 million contract for a standardized supply of marijuana for research and medical purposes. The marijuana will be grown 360 m underground in an unused section of an active mine below a lake near the town of Flin Flon, Manitoba. The extreme growing location will allow both genetic containment and high security. It will be the country’s first legal supply of marijuana. Canadians have recently been
http://plants.trends.com 1360-1385/01/$ – see front matter © 2001 Elsevier Science Ltd. All rights reserved.
releasing the plants into constant light. They used highly reproducible oligonucleotidebased arrays (GeneChip arrays) representing ~8200 different genes. More than 450 of these genes displayed circadian changes in steady-state mRNA levels. Many of the cycling genes identified in the experiment could be classified into functional groups based upon their known or predicted physiological roles. The functional clusters included genes involved in photosynthetic light harvesting, synthesis of protective phenolic compounds, lipid modification, carbon metabolism and partitioning, nitrogen and sulfur assimilation, cell elongation and flowering, and genes coding for informational photoreceptors such as phyB, cryptochromes and phototropin. Using a computational analysis of oscillating genes, the authors were able to identify a novel promoter element that confers circadian rhythmicity on expression, and the functional role of this conserved promoter motif was confirmed through mutational analysis.
TRENDS in Plant Science Vol.6 No.3 March 2001
What is the primary driving force for circadian clock evolution? Perhaps the main advantage that plants gain by putting gene expression under circadian regulation is the ability to anticipate diurnal changes in the environment, such as fluctuations of light, UV and temperature levels. Or perhaps the key function of the clock is to provide a temporal framework for internal coordination of physiological activities. ‘...this study has given us the first opportunity to listen for a full 48 h to an Arabidopsis gene-expression symphony.’ The fact that several photosynthetic genes, and genes involved in the synthesis of phenolic sunscreens and in chilling tolerance were found to be under circadian control is certainly consistent with the first hypothesis. In addition, the demonstration of circadian rhythmicity in the expression of genes involved in carbon partitioning and in the energy-intensive processes of nitrogen and sulfur assimilation is indeed consistent with
97
the idea that the clock plays a key role in maintaining internal balance and physiological harmony. In fact, for those interested in functional coordination in plants, reading the paper of Harmer et al.1 will evoke a similar sensation as listening to a philharmonic orchestra after attending rehearsals of individual players or sections. By simultaneously monitoring the circadian regulation of a few thousand genes, this study has given us the first opportunity to listen for a full 48 h to an Arabidopsis gene-expression symphony. The perspective afforded by studies such as this sets the stage to discover novel expression ‘sounds’, and to appreciate the role of each particular gene player in the broad context of plant physiological homeostasis and functional organization. 1 Harmer, S.L. et al. (2001) Orchestrated transcription of key pathways in Arabidopsis by the circadian clock. Science 290, 2110–2113
Carlos L. Ballaré [email protected]
In Brief
Healing power of plants Alzheimer’s, a degenerative brain disease, represents one of the cruellest blows associated with ageing. However, hope is at hand with reports that a compound, galantamine, found in bulbs of daffodil (Narcissus pseudonarcissus) can delay some of the symptoms of the illness [Br. Med. J. (2000) 321, 1–7]. Galantamine acts partly by stimulating nicotine-receptors in the brain, and partly by inhibiting acetylcholinesterase, thereby preserving the otherwise diminishing levels of acetylcholine. In this way, its action is similar to smoking tobacco, but without the harmful effects associated with this more infamous plant product. [Dobson, R. (2001) Daily Mail (UK) 5 September.] NC
It’s official: Brussels sprouts really are good for you Parents frequently experience problems getting children to ‘eat their greens’. Now a research review from a group at the University of Washington (USA) [Am. J. Clin. Nutr. (2000) 72, 1424–1435] provides even greater reason for parents to persist in feeding vegetables such as Brussels sprouts, cabbage and spinach to their offspring. That
work shows that the trace chemicals that give such food its bitter taste are often associated with cancer prevention and other health benefits. Unfortunately, in efforts to make these vegetables more palatable, the food industry has largely removed this bitterness, either chemically during processing or by breeding and selection. It is suggested that the Mediterranean practice of lightly seasoning with salt and a dash of olive oil would be a better way of coping with the unpleasant taste, and do more good. NC
Castor plants’ promising future Although castor has fallen out of popularity as a common crop, that might change in the future. Oil from castor beans contains hydroxy fatty acids and is essential for making high quality industrial lubricants. Castor’s two main problems are that the oil-rich seed contains powerful allergens and ricin, a toxin seven times more deadly than cobra venom. The genes crucial for both ricin and the allergens are known. Now, Thomas McKeon and Grace Chen, both at USDA-ARS (Albany, CA, USA) are the first in the world to produce genetically engineered castor plants. The first transgenic castor plants contained marker genes, but the group is planning to use anti-sense
technology to reduce the allergens and ricin toxin in castor. The world market for castor oil is lucrative at A$400 million per year. Photograph by Brian Prechtel, courtesy of ARS. (http://www.ars.usda.gov/ is/AR/archive/jan01/plant0101.htm) TS
Canada mines for marijuana The government of Canada has awarded a C$5.7 million contract for a standardized supply of marijuana for research and medical purposes. The marijuana will be grown 360 m underground in an unused section of an active mine below a lake near the town of Flin Flon, Manitoba. The extreme growing location will allow both genetic containment and high security. It will be the country’s first legal supply of marijuana. Canadians have recently been
http://plants.trends.com 1360-1385/01/$ – see front matter © 2001 Elsevier Science Ltd. All rights reserved.