September 13, 2006, 5:10 AM CT
Do green markets actually lead to improvements in environmental quality?
Goods and services with environmental benefits are a growing part of a number of sectors of the economy, and a timely new paper from the current issue of the Journal of Political Economy analyzes how our willingness to pay more for environmentally friendly products actually influences environmental quality and social welfare. Surprisingly, the study finds that under certain reasonable conditions, green markets can actually discourage private support of public environmental entities.
Using a model of impure public goods, Matthew J. Kotchen (University of California, Santa Barbara) analyzes goods that have both private and public components, each of which is available individually. For example, shade-grown coffee is grown not on deforested plantations, but under the canopy of tropical forests. Thus, consumers are not only buying coffee, which is a traditional private good, but also biodiversity conservation. However, consumers also have the option to buy conventional coffee and donate directly to tropical conservation.
"Eventhough green markets are promoted to improve environmental quality and promote social welfare, their actual effects may be detrimental to both," writes Kotchen. "These results, along with the conditions sufficient to rule them out, provide new insight into the potential advantages and disadvantages of green markets as a decentralized mechanism of environmental policy".........
Posted by: Erica Permalink Source
September 9, 2006, 12:08 AM CT
Scientists Take A Global View Of The Epigenome
The Arabidopsis rosette sits on a map of transcripts
A collaboration between scientists at the Salk Institute for Biological Studies and the University of California at Los Angeles captured the genome-wide DNA methylation pattern of the plant Arabidopsis thaliana - the "laboratory rat" of the plant world - in one big sweep.
"In a single experiment we recapitulated 20 years worth of anecdotal findings and then some," says senior author Joseph Ecker, Ph.D., a professor in the Salk Institute's Plant Biology Laboratory. "Previously, only a hand full of plant genes were known to be regulated by methylation. In addition to those, we found hundreds of others".
These technological innovations, pioneered by Ecker's team and that of Steve Jacobsen, Ph.D., a Howard Hughes Medical Institute investigator at UCLA, should have broad impact on the analysis of the human genome, stem cell biology and therapeutic cloning. Their findings will appear in a forthcoming issue of Cell.
Our view of heredity has largely been written in the language of DNA, but recent discoveries in a field known as epigenetics - the study of heritable changes in gene function that occur without changing the letters of the DNA alphabet - show that how a cell "reads" those letters is critical.
Methylation is chemical modification of one letter C (cytosine) of the four letters (A, G, C, and T) reiterated in our DNA. Adding a bulky methyl group to a C often blocks interaction with proteins mandatory to activate gene expression, effectively silencing the methylated gene.........
Posted by: Erica Permalink Source
September 9, 2006, 9:45 AM CT
Gene Silencing In Plants
Biologists at Washington University in St. Louis have made an important breakthrough in understanding a pathway plant cells take to silence unwanted or extra genes using short bits of RNA. Basically, they have made it possible to see where, and how, the events in the pathway unfold within the cell, and seeing is believing, as the old saying goes.
Craig Pikaard, Ph.D., Washington University professor of biology in Arts & Sciences and his collaborators have described the roles that eight proteins in Arabidopsis plants play in a pathway that brings about DNA methylation, an epigenetic function that involves a chemical modification of cytosine, one of the four chemical subunits of DNA. Without proper DNA methylation, higher organisms from plants to humans have a host of developmental problems, from dwarfing in plants to certain tumors in humans, and death in mice.
One role of DNA methylation is to turn off repetitive genes, such as transposable elements that can move or spread throughout a genome and disrupt other gene functions if left unchecked. There is also interest in DNA methylation because understanding how some genes are selectively silenced and how silenced alleles can be turned on again may someday have practical benefits. For instance, tumor suppressor genes that normally help keep cells from dividing uncontrollably are often silenced by DNA methylation and histone (proteins that wrap DNA) modifications in cancer cells, contributing to tumor growth. And certain blood disorders resulting from defective genes expressed in adults might be alleviated if versions of those same genes that are only expressed very early in development, but are then silenced in adults, could only be turned on again.........
Posted by: Erica Permalink Source
September 5, 2006, 10:11 PM CT
Biological Switch from Spinach Molecule
Nanoresearchers have transformed a molecule of chlorophyll-a from spinach into a complex biological switch that has possible future applications for green energy, technology and medicine.
The study offers the first detailed image of chloropyhll-a - the main ingredient in the photosynthesis process - and shows how researchers can use new technology to manipulate the configuration of the spinach molecule in four different arrangements, report Ohio University physicists Saw-Wai Hla and Violeta Iancu in today's early edition of the journal Proceedings of the National Academy of Sciences.
The researchers used a scanning tunneling microscope to image chlorophyll-a and then injected it with a single electron to manipulate the molecule into four positions, ranging from straight to curved, at varying speeds. (View a movie here) Though the Ohio University team and others have created two-step molecule switches using scanning tunneling microscope manipulation in the past, the new experiment yields a more complex multi-step switch on the largest organic molecule to date.
The work has immediate implications for basic science research, as the configuration of molecules and proteins impacts biological functions. The study also suggests a novel route for creating nanoscale logic circuits or mechanical switches for future medical, computer technology or green energy applications, said Hla, an associate professor of physics.........
Posted by: Erica Permalink Source
September 5, 2006, 4:47 AM CT
Global Changes Alter Plant Growth
Any gardener knows--different plant species mature at different times. Researchers studying plant communities in natural habitats call this phenomenon "complementarity." It allows a number of species to co-exist because it reduces overlap in the time period when species compete for limited resources. Now, in a study posted online the week of Sept. 4 in the Proceedings of the National Academy of Sciences, ecologists working at Stanford's Jasper Ridge Biological Preserve report evidence that climate change may alter this delicate balance.
"In the natural world, species have evolved to be finely attuned to the seasons--timing is everything," said lead author Elsa Cleland, who performed this research as part of her doctoral dissertation at Stanford and is now a postdoctoral fellow at the National Center for Ecological Analysis and Synthesis in Santa Barbara, Calif. "If climate change alters the timing of plant activity, then it could have a domino effect, impacting the feeding, breeding or migration patterns of the animals that rely on particular plant species".
Cleland's co-authors include Nona R. Chiariello, research coordinator of the Jasper Ridge Biological Preserve; Scott Loarie, who assisted with this research while a Stanford undergraduate; Christopher B. Field, director of the Carnegie Institution's Department of Global Ecology (located on the Stanford campus) and faculty director of Jasper Ridge Biological Preserve, and Harold A. Mooney, the Paul S. Achilles Professor of Environmental Biology at Stanford.........
Posted by: Erica Permalink Source
September 3, 2006, 5:44 AM CT
The Nanocosmos of the Cell
Both figures above show the filaments in a human nerve cell; left with a common confocal microscope, right with a STED microscope
There is an amazing and mysterious nanocosmos out there largely unexplored. How viruses infect a cell, how nerve cells transport signals or how proteins work - the nanocosmos of nature remains hidden to the human eye. However, in order to still be able to perceive the seemingly invisible, we need to enlarge the object - for example, with a fluorescence microscope. Fluorescent markers are attached to proteins and other biomolecules so that researchers can observe the marker. For a long time, low resolution prevented a deeper look into the function of proteins - single proteins with their dimension of 2-20 nanometers diameter were, until now, just too small.
Researchers at the Max Planck Institute for Biophysical Chemistry in Gottingen have now achieved a resolution of up to 15nm with their STED microscope (Stimulated Emission Depletion). Their fluorescence microscope is thereby twelve times sharper than a conventional one. Already in April, the team of researchers lead by Professor Stefan Hell achieved a detail sharpness of up to 60 nanometers in cells.
Only a few years ago, physicists believed that it was impossible to resolve details that lie closer together than 200 nanometers. This limit is imposed by Abbe's Law, whereby the resolution of a light microscope cannot be more accurate than half of the wavelength of light entering the microscope.........
Posted by: Kelly Permalink Source
September 2, 2006, 9:58 PM CT
So Many Weeds In Your Garden This Year?
A 15-year study of flixweed, a member of the mustard family, helps explain plant population oscillations and may be useful in crop protection.
Credit: Courtesy J.L. Gonzalez-Andujar
Some years, no matter how diligently you pull, your backyard garden is always covered with weeds. Other years, with the minimum of effort, your garden remains weed-free. What is the cause of these oscillations? A group of weed researchers based at the Spanish National Research Council (CSIC) spent fifteen years studying flixweed a member of the mustard family usually found in areas where the ground has been cultivated or disturbed in an attempt to identify the processes underlying these fluctuations.
"The failure to recognize the intrinsic nature of a number of weed population changes may result in over-application of control inputs, with subsequent negative economic and environmental effects," says Jose Gonzalez-Andujar, who co-authored the study, forthcoming in The American Naturalist, with Cesar Fernandez-Quintanilla and Luis Navarrete.
A number of populations exhibit cyclic oscillations. Everybody can recall a summer where mosquitoes hindered attempts at al fresco dining. These cycles can be produced by climatic conditions or by internal feedback mechanisms. However, in contrast with studies of insect and animal populations, little attention has been directed at the study of cycles in plants. What happens with your garden weeds?.
The scientists demonstrate that there are some intrinsic mechanisms that explain observed plant oscillations more specifically, evidence of cycles produced by delayed density dependence in a plant population growing under field conditions. This study can have a capital importance in crop protection.........
Posted by: Erica Permalink Source
September 2, 2006, 9:51 PM CT
Insights Into Spread Of Plant Diseases By Insects
Scientists from Penn State University and the University of Virginia show that the spread of diseases by insects can be described by equations similar to those that describe the force of gravity between planetary objects. Their findings are detailed in the recent issue of The American Naturalist.
Insects tend to transmit diseases in the course of feeding on plants, and their movement between plants is influenced by plant quality (how good of a meal they'll get) and the distance between plants, or, how far they'll have to travel to get to the next meal, explain Matthew Ferrari, Jessica Partain, Janis Antonovics, and Ottar Bjornstad.
"It turns out insects are more likely to move shorter distances between better plants," write the authors. "Interestingly, then, the probability of disease being passed between two plants goes up if they are closer and/or better, which parallels the stronger gravity between closer and larger planets".
The scientists tracked a fungal disease spread by bees and moths in the course of pollinating and feeding on nectar from white campion flowers at the University of Virginia's Mountain Lake Biological Station. As predicted by the behaviour of insects, the disease was more likely to spread shorter distances between plants that had a number of flowers.........
Posted by: Erica Permalink Source
September 2, 2006, 9:21 PM CT
Genome Info From Plant Destroyers
An international team of researchers has published the first two genome sequences from a destructive group of plant pathogens called Phytophthora--a name that literally means "plant destroyer." The more than 80 species of fungus-like Phytophthora (pronounced "fy-TOFF-thor-uh") attack a broad range of plants and together cost the agriculture, forestry and nursery industries hundreds of billions of dollars each year.
Even though Phytophthora are similar to fungi, most fungicides are ineffective at controlling them. The information gained from studying the genomic sequences of P. ramorum and P. sojae will help researchers devise strategies to combat not only these two species, but also other disease-causing Phytophtora.
The study appears in the Sept. 1 issue of the journal Science.
Phytophthora sojae, an endemic pathogen of soybeans, is responsible for $1 billion to $2 billion in losses worldwide each year. Phytophthora ramorum is linked to sudden oak death, a disease that has devastated the nursery industry and oak ecosystems in California, Oregon and Washington.More than 1 million native oak and tanoak trees have been lost to the disease.
In addition to soybean and oak, Phytophthora species cause disease in avocado, coconut, papaya, pineapple, potato, strawberry and watermelon, to name a few. The pathogen also destroys an estimated 450,000 tons of cocoa beans with a resulting $400 million loss in chocolate production each year.........
Posted by: Erica Permalink Source
September 2, 2006, 9:15 PM CT
Eco-friendly Tool For Managing Weeds
Eventhough plant pathogens are typically viewed as detrimental, plant pathologists with the American Phytopathological Society (APS) say plant pathogens may be a successful, eco-friendly tool for managing weeds.
"The use of plant pathogens to suppress weeds is considered as one of the alternative weed control options for areas or production systems where the use of chemical herbicides is not permitted or feasible," said Erin Rosskopf, USDA, Agricultural Research Service, Fort Pierce, FL. "Plant pathogens may also be used when the herbicide selection or usage must be rotated with other control methods in order to prevent the development of resistant weeds or lessen the impact of herbicides on the environment," she said.
Weed management is important due to the amount of damage weeds can cause to agricultural productivity. Weeds can reduce crop yields by as much as 12 percent (causing up to $32 billion in losses), based on the potential value of all U.S. crops of approximately $267 billion/year. Weeds also pose serious ecological problems. Invasive weeds are capable of altering ecosystem processes and displacing native plant and animal species. In addition, weeds serve as reservoirs for plant pathogens that impact crops.
As per Rosskopf, there are two approaches used for managing weeds with plant pathogens-the classical biological control approach and the bioherbicides approach. The classical biocontrol approach uses a pathogen imported from a foreign location to control a native or naturalized weed with minimal technological manipulations.........
Posted by: Erica Permalink Source
