July 12, 2007, 5:37 AM CT

Reef fish need longer break

In the longest running study on how fish populations in coral reef systems recover from heavy exploitation, scientists from the Wildlife Conservation Society (WCS) and others have observed that the fish can recover, but they need lots of time decades in some cases. The study appears in a recent edition of the journal Ecological Applications.

With nearly continuous data spanning some 37 years from four national marine parks off the coast of Kenya which were closed to fishing at different times, the study observed that commercially important species such as parrotfish, wrasses, and surgeonfish can take a quarter of a century to recover fully. More importantly, the ecological equilibrium needed for a healthy reef system, which relies on the interplay of a number of fish, invertebrate, and plant species, take even longer to achieve, and certainly longer than the length of the study. Most fish recovery studies are conducted with small data sets in short durations of time.

Theres a pressing need for long-term studies on how fish communities in reef ecosystems rebuild when fishing is banned, said WCS researcher Dr. Tim McClanahan, the lead author of the study. This study gives us some important insights in how the different fish species recover and how these communities affect the health of the reef as a whole......... Posted by: Kelly      Read more         Source

July 11, 2007, 5:24 AM CT

Brightly colored birds most affected by Chernobyl radiation

Brightly coloured birds are among the species most adversely affected by the high levels of radiation around the Chernobyl nuclear plant, ecologists have discovered. The findings published online in the British Ecological Society's Journal of Applied Ecology help explain why some species are harder hit by ionising radiation than others.

Dr Anders Mller of the Universit Pierre et Marie Curie and Professor Timothy Mousseau of the University of South Carolina examined 1,570 birds from 57 different species in the forests around Chernobyl at varying distances from the reactor. They observed that populations of four groups of birds those whose red, yellow and orange plumage is based on carotenoids, those that laid the biggest eggs, and those that migrated or dispersed the furthest declined more than other species.

The intriguing results centre on the role of antioxidants chemicals that help protect living organisms from the damaging effects of free radicals. Certain activities use up large amounts of antioxidants. These include producing carotenoid-based pigments for feathers, migrating long distances and laying large eggs (birds lay down antioxidants in their eggs, and will deposit larger amounts of antioxidants in larger eggs). Mller and Mousseau hypothesized that because they had fewer antioxidants left to mop up dangerous free radicals, these birds would most adversely affected by exposure to radiation around Chernobyl......... Posted by: Kelly      Read more         Source

July 10, 2007, 5:28 AM CT

Invisible gases form most organic haze in urban, rural areas

A new study involving the University of Colorado at Boulder shows that invisible, reactive gases hovering over Earth's surface, not direct emissions of particulates, form the bulk of organic haze in both urban and rural areas around the world.

Many science and health professionals have believed sources that spew soot and other tiny particles directly into the air were the primary culprit in the formation of organic haze. But a new study by researchers at CU-Boulder's Cooperative Institute for Research in Environmental Sciences show aerosols formed chemically in the air account for about two-thirds of the total organic haze in urban areas and more than 90 percent of organic haze in rural areas.

The study was led by Qi Zhang, a former CIRES scientist now at the Atmospheric Sciences Research Center at State University of New York, Albany and CIRES researcher Jose-Luis Jimenez. The study was published in the July 7 online issue of Geophysical Research Letters.

The scientists compared concentrations of directly emitted, or primary, aerosols with chemically formed, or secondary aerosols. They surveyed urban areas, areas downwind of urban areas and rural areas from 37 sites in 11 countries.

"What we're seeing is that concentrations of secondary organic aerosols decrease little downwind from urban areas," said Jimenez, also an assistant professor in CU-Boulder's chemistry and biochemistry department. "That tells us there has to be an extended source or continuous formation for the pollution"......... Posted by: Erica      Read more         Source

July 10, 2007, 5:22 AM CT

External Light Regulate Plant Growth

Most plants and animals show changes in activity over a 24-hour cycle. Now, for the first time, scientists have shown how a plant combines signals from its internal clock with those from the environment to show a daily rhythm of growth.

Using time-lapse photography, postdoctoral researcher Kazunari Nozue, with colleagues from UC Davis and the University of Lausanne, Switzerland, observed that the shoots of Arabidopsis seedlings show a spurt of growth once a day. The timing of that growth spurt is controlled by both the plant's internal clock and by exposure to light, acting on two genes called PIF 4 and PIF 5.

"It's a nice, elegant mechanism for how these two systems interact," said Julin Maloof, assistant professor of plant biology at UC Davis, who is senior author on the paper.

When the seedlings are grown in constant light, most growth occurs in the late afternoon. But when the plants were moved to a more natural light/dark cycle, growth shifted several hours to occur just before dawn. In nature, that is the time when water is commonly most available.

The scientists identified the two genes, PIF 4 and PIF 5, that are connected to plant growth and regulated by the internal clock. The PIF 4 and 5 genes are "switched on" to make protein during the day, switch off after dark but then turn on again late in the night. But the proteins made by PIF 4 and PIF 5 break down when exposed to light. So while the internal clock drives transcription of the genes to produce proteins, external light removes the protein......... Posted by: Erica      Read more         Source

July 10, 2007, 5:20 AM CT

'Virtual' mouse brains now available online

A multi-institutional consortium including Duke University has created startlingly crisp 3-D microscopic views of tiny mouse brains -- unveiled layer by layer -- by extending the capabilities of conventional magnetic resonance imaging.

"These images can be more than 100,000 times higher resolution than a clinical MRI scan," said G. Allan Johnson, Duke's Charles E. Putman Distinguished Professor of radiology and professor of biomedical engineering and physics. He is first author of a report describing the innovations set for publication in the research journal NeuroImage. View it online at http://tinyurl.com/2upj7n.

Images on the website for Duke's Center for In Vivo Microscopy http://www.civm.duhs.duke.edu/, which Johnson directs, reveal examples of these innovations in action. In one video two different mouse brains -- one from a normal animal and the other from a rodent missing a gene associated with mental abnormalities -- seem to assemble themselves before the viewer's eyes, structure by structure.

Watch the video with Johnson at http://realmedia.oit.duke.edu/ramgen/news/brain_imaging.rm (RealMedia) or http://quicktime.oit.duke.edu/news/brain_imaging.mov (Quicktime).

After building up like time-lapse photos of opening flowers, the side-by-side brain images begin revolving as overlying tissues dissolve into computer-rendered transparency. What remains visible, seemingly floating over the bases of the animals' skulls, are two color-coded brain structures -- the ventricles and hippocampus -- showing different volumes resulting from specific genetic differences......... Posted by: Kelly      Read more         Source

July 10, 2007, 4:56 AM CT

miscanthus more productive than switchgrass

At the annual meeting of the American Society of Plant Biologists in Chicago (July 7-11, 2007), researchers will present findings on how to economically and efficiently produce plant crops suitable for sustainable bioenergy. Improving the production of such biomass is important because it should significantly ease and eventually replace dependence on petroleum-based fuels. Biomass is plant material, vegetation or agricultural waste used as fuel.

Converting biomass into biofuels can be costly and slow. Two crops, both classified as C4 perennial grasses, have been studied extensively to determine how best to improve costs and production rates. Switchgrass (Panicum virgatum) has been trialed across the United States. Miscanthus (Miscanthus x giganteus) has been studied throughout the European Union. Both show great promise, but until now, nobody has been sure which crop is more efficacious. The study completed by Frank Dohleman of the Plant Biology Department at University of Illinois at Urbana-Champaign and colleagues, is the first to compare the productivity of the two grasses in side-by-side field trials. Results from trials throughout Illinois show that Miscanthus is more than twice as productive as switchgrass.

Dohlemans team, which included Dafu Wang, Andrew D.B. Leakey & Stephen P. Long also of University of Illinois, along with Emily A. Heaton of Ceres Inc., theorized that Miscanthus produces more usable biomass than switchgrass because of these three key attributes:........ Posted by: Erica      Read more         Source

July 8, 2007, 10:27 PM CT

Elevated CO2 in atmosphere weakens defenses of soybeans

In research to be presented at the annual meeting of the American Society of Plant Biologists in Chicago (July 7-11, 2007), researchers will show that elevated CO2 may negatively impact the relationship between some plants and insects. Elevated CO2 is considered to be a serious catalyst of global change. Its effects can be felt throughout the ecosystem, including the insect-plant food chain link. Safeguarding highly-usable crops is of great importance to a number of local and national economies.

A number of plants have inherent enzyme-based defenses that are released during insect attack. This study observed that when soybeans (Glycine max) were exposed to elevated amounts of CO2 the plants became more susceptible to attack by Japanese beetles (Popillia japonica). Furthermore, as these beetles consumed the weakened soybeans, the insects invasive abilities were intensified.

Dr. Jorge Zavala, Sr. of the Institute for Genomic Biology at the University of Illinois, and colleagues conducted tests in which they reviewed this herbivorous attack-defense cycle. They studied soybeans grown in traditional field conditions but with additional exposure to ambient CO2. The results showed that the amount of cysteine proteinase inhibitors (CystPls) expressed in the genes decreased when soybeans were exposed to elevated CO2. CystPls is naturally produced by soybeans when they are under insect attack. It inhibits further attack once the invader has ingested it......... Posted by: Erica      Read more         Source

July 8, 2007, 10:08 PM CT

Genetically Engineered Maize

Maize streak viruses (MSV), geminiviruses that can destroy most of a maize crop, are endemic to sub-Saharan Africa and adjacent Indian Ocean islands where they are transmitted by leafhoppers in the genus Cicadulina. Maize can supply 50% of the caloric intake in sub-Saharan Africa but, in certain years, a farmers entire crop can be wiped out. Now, researchers at the University of Cape Town, South Africa, along with colleagues at the South African seed company, PANNAR Pty Ltd, have developed a resistant variety of maize that they hope will help alleviate food shortages as well as promote the reputation of genetically engineered (GE) foods in Africa. Dr. Dionne Shepherd of the University of Cape Town will be presenting the results of her recent work and that of coauthors B. Owor, R. Edema, A. Varsani, D.P. Martin, J.A. Thomson and E.P. Rybicki, at the annual meeting of the American Society of Plant Biologists in Chicago (July 8, 11:20 AM) in a major symposium on Plant Biology in Sub-Saharan Africa organized by Debby Delmer of UC Davis.

Maize, which originated in Mexico, was carried to Africa in the 1500s and eventually displaced native food crops such as sorghum and millet. Maize streak virus, an endemic pathogen of native African grasses, was then carried to maize plants by viruliferous leafhoppers. African researchers have been working for more than a quarter century on developing resistant varieties of maize by selecting and crossing varieties with various degrees of resistance to the virus......... Posted by: Erica      Read more         Source

July 5, 2007, 9:39 PM CT

Benefits Of Butterfly Defenses

Scientists observed the behaviour of Great-tits foraging for artificial prey to understand more clearly how a species evolves to protect themselves from predators.

Insects, such as butterflies, have bright contrasting colour patterns that indicate to predators that they are not likely to be palatable. In order to gain greater protection from predators, however, some butterflies evolve to imitate the warning signals of a more highly defended species a phenomenon known as mimicry. Researchers at Liverpool, in collaboration with the University of Jyvskyl in Finland, tested which species of butterfly benefits the most from this technique.

Hannah Rowlands explains: Prior studies have suggested that the relationship between two look-alike species is parasitic, whereby a tastier insect reaps all the benefits of resembling a more unpalatable species. Researchers have argued that predators may get confused as to which species is most edible and which is not, resulting in them eating more of the unpalatable species than they normally would have done.

We observed that the two species of butterfly we used in our research do not undermine each other and benefit mutually from looking like each other. Copying in this sense is the highest form of flattery!

In order to understand how this technique benefited both species of butterfly the team devised an experiment in an indoor aviary and observed the behaviour of Great-tits as they attacked artificial prey made from almond filled paper parcels......... Posted by: Kelly      Read more         Source

July 5, 2007, 9:37 PM CT

Chickens And Earth's Magnetic Field

40 years ago, Prof. Dr. Wolfgang Wiltschko was the first to prove that migrating robins use the Earths magnetic field to direct themselves during migration. Their magnetic sensor showed them the course of the field lines of the Earths magnetic field. This produces an inclination compass that reacts to the inclination of the Earths magnetic field to the surface of the Earth, thus distinguishing between pole-wards (the side on which the field lines incline downwards) and equator-wards (the side on which they incline upwards). The inbuilt compass is additionally finely tuned to the field strength of the Earths local magnetic field, but can also be flexibly adapted to other field strengths that the birds encounter in the course of migration. Since that time a compass of this kind has been found in more than 20 species of birds, the majority of them being those songbirds that undertake annual migration. An international working group under the direction of Wolfgang und Roswitha Wiltschko of Frankfurt University has now succeeded in demonstrating the presence of a magnetic sense of direction in domestic chickens as well.

For this purpose, newly hatched chicks were imprinted on a red ball which they from then on regarded as their mother. The scientists then hid the ball behind one of four screens, and taught the chickens by intensive training that the mother was always behind the screen that was in the northerly direction. To demonstrate that the chicken senses this compass point by means of its magnetic sense of direction, the scientists set up an artificial magnetic field in an easterly direction and the chickens did actually seek their mother behind the screen that lay to the east......... Posted by: Kelly      Read more         Source