January 11, 2010, 7:53 AM CT

Can a drop of water cause sunburn or fire?

To the gardening world it may have always been considered a fact, but science has never proved the widely held belief that watering your garden in the midday sun can lead to burnt plants. Now a study into sunlit water droplets, published in New Phytologist, provides an answer that not only reverberates across gardens and allotments, but may have implications for forest fires and human sunburn.

"The problem of light focusing by water droplets adhered to plants has never been thoroughly investigated, neither theoretically, nor experimentally", said lead researcher Dr Gabor Horvath, from Hungary's Eotvos University. "However, this is far from a trivial question. The prevailing opinion is that forest fires can be sparked by intense sunlight focused by water drops on dried-out vegetation".

The team conducted both computational and experimental studies to determine how the contact angle between the water droplet and a leaf affects the light environment on a leaf blade. The aim was to clarify the environmental conditions under which sunlit water drops can cause leaf burn.

These experiments observed that water droplets on a smooth surface, such as maple or ginkgo leaves, cannot cause leaf burn. However in contrast the team observed that floating fern leaves, which have small wax hairs, are susceptible to leaf burn. This is because the hairs can hold the water droplets in focus above the leaf's surface, acting as a magnifying glass. The latter not only partly confirms the widely held belief of gardeners, but also opens an analogous issue of sunburn on hairy human skin after bathing......... Posted by: Erica      Read more         Source

January 6, 2010, 7:50 AM CT

From crickets to whales

Researchers who compare insect chirps with ape calls may look like they are mixing aphids and orangutans, but scientists have found common denominators in the calls of hundreds of species of insects, birds, fish, frogs, lizards and mammals that can be predicted with simple mathematical models.

Compiling data from nearly 500 species, researchers with the University of Florida and Oklahoma State University have found the calls of crickets, whales and a host of other creatures are ultimately controlled by their metabolic rates in other words, their uptake and use of energy.

"Very few people have compared cricket chirps to codfish sounds to the sounds made by whales and monkeys to see if there were commonalities in the key features of acoustic signals, including the frequency, power and duration of signals," said James Gillooly, Ph.D., an assistant professor in the department of biology at UF's College of Liberal Arts and Sciences and a member of the UF Genetics Institute. "Our results indicate that, for all species, basic features of acoustic communication are primarily controlled by individual metabolism, which in turn varies predictably with body size and temperature. So, when the calls are adjusted for an animal's size and temperature, they even sound alike"......... Posted by: Kelly      Read more         Source

January 5, 2010, 8:57 AM CT

Preserving genetic diversity of rice

Rice is one of the most important crops worldwide, as it feeds over half of the world's population. Domesticated rice is an important supply of the world's rice. However, these strains are genetically static and cannot adapt to changing growing conditions. Traditional varieties, or landraces, of rice are genetically evolving and provide a pool of traits that can be tapped to improve crops worldwide.

Research from Barbara A. Schaal, Ph.D., the Mary-Dell Chilton Distinguished Professor of biology in Arts & Sciences at Washington University in St. Louis, and her colleagues at Chiang Mai University in Thailand shows how natural genetic drift and agricultural practices of the traditional farmers combine to influence the genetic diversity of a given landrace of rice.

Schaal is also involved in science policy, serving as vice president of the National Academy of Sciences and recently appointed to the President's Council of Advisors on Science and Technology.

Schaal and her colleagues studied a landrace of rice grown by the Karen people in Thailand. They compared the genetic variation among the same variety of rice grown in different fields and villages. The genetics of the rice population fits the isolation by distance model, much like a native plant species. The further apart fields are, the more genetically distinct they are......... Posted by: Erica      Read more         Source

January 4, 2010, 8:12 AM CT

Nervous culprit found for Tassie devil facial tumor disease

Cells that protect nerves are the likely origin of the Devil Facial Tumour Disease (DFTD) that has been devastating Australia's Tasmanian devil population, an international team of researchers has discovered.

Devil Facial Tumour Disease (DFTD) is a transmissible cancer that affects only Tasmanian devils and was first reported in 1996. It is spread by biting and quickly kills the animals. The disease is characterised by large tumours, mostly on the face and mouth, which often spread to internal organs.

The research collaboration, led by Australian scientists, has observed that DFTD originates from cells called Schwann cells, which protect peripheral nerve fibres.

The results have been published recently in the international journal Science

Through the discovery, the team has now identified a genetic marker that could be used to accurately diagnose the perplexing cancer, which has seen the devil listed as endangered and facing extinction.

Main author Dr Elizabeth Murchison from the Australian National University said the Schwann cell discovery was significant as there are currently no specific diagnostic tests, therapys or vaccines available for the disease.

"We took biopsies from devil tumours and extracted genetic data from them," Dr Murchison said......... Posted by: Kelly      Read more         Source

January 4, 2010, 8:10 AM CT

To a mosquito, matchmaking means

Scientists have new insight into the sex lives of the much-maligned mosquitoes that are responsible for the vast majority of malaria deaths, as per a report published online on December 31st in Current Biology, a Cell Press publication. In finding a partner of the right species type, male and female mosquitoes depend on their ability to "sing" in perfect harmony. Those tones are produced and varied based on the frequency of their wing beats in flight.

"Everyone must be familiar with the maddening whine a mosquito makes as it hones in for a bite," said Gabriella Gibson of the University of Greenwich at Medway. "There's no doubt a number of of us have wondered why it makes its presence so obvioussurely, after all of these centuries of blood-feeding, selection should have favored a more stealthy approach that would leave mosquitoes less vulnerable to the defensive attacks of its unsettled host. Our findings suggest that mosquitoes rely on the sounds they make to attract a mate of the right species, a behavior that is far more vulnerable to selection than avoiding the risk of being squashed by the rare host that is still awake at feeding time".

The Anopheles gambiae mosquitoes in fact include a considerable amount of genetic diversity, representing a complex of seven species and several chromosomal forms. And that diversity comes with real consequences for humans, explained Gibson and Ian Russell of the University of Sussex. The complexity of malaria epidemiology and control is due in part to the mosquito's remarkable genetic plasticity, enabling its adaptation to a widening range of human-influenced habitats......... Posted by: Kelly      Read more         Source

January 4, 2010, 8:07 AM CT

Evolution caught red-handed

Mutations are the raw material of evolution. Charles Darwin already recognized that evolution depends on heritable differences between individuals: those who are better adapted to the environment have better chances to pass on their genes to the next generation. A species can only evolve if the genome changes through new mutations, with the best new variants surviving the sieve of selection. Researchers at the Max Planck Institute for Developmental Biology in Tübingen, Gera number of, and Indiana University in Bloomington have now been able to measure for the first time directly the speed with which new mutations occur in plants. Their findings shed new light on a fundamental evolutionary process. They explain, for example, why resistance to herbicides can appear within just a few years. (Science, January 1, 2010).

"While the long term effects of genome mutations are quite well understood, we did not know how often new mutations arise in the first place," said Detlef Weigel, director at the Max Planck Institute in Gera number of. It is routine today to compare the genomes of related animal or plant species. Such comparisons, however, ignore mutations that have been lost in the millions of years since two species separated. The teams of Weigel and his colleague Michael Lynch at Indiana University therefore wanted to scrutinize the signature of evolution before selection occurs. To this end, they followed all genetic changes in five lines of the mustard relative Arabidopsis thaliana that occurred during 30 generations. In the genome of the final generation they then searched for differences to the genome of the original ancestor......... Posted by: Erica      Read more         Source

December 30, 2009, 8:09 AM CT

New Acoustic Tools to Study Marine Mammalsand Fish

Over the past decade, scientists have developed a variety of reliable real-time and archival instruments to study sounds made or heard by marine mammals and fish. These new sensors are now being used in research, management, and conservation projects around the world, with some very important practical results. Among them is improved monitoring of endangered North Atlantic right whales in an effort to reduce ship strikes, a leading cause of their deaths.

"The tools available to both acquire and analyze passive acoustic data have undergone a revolutionary change over the last ten years, and have substantially increased our ability to collect acoustic information and use it as a functional management tool," said Sofie Van Parijs, main author and a bioacoustician at NOAA's Northeast Fisheries Science Center laboratory in Woods Hole, Mass. "These tools have significantly improved monitoring of North Atlantic right whales and enhanced the efficacy of managing ship traffic to reduce ship strikes of whales through much of the western North Atlantic off the U.S. East Coast".

Van Parijs is one of a number of researcher whose work is decribed this month in the journal Marine Ecology Progress Series. Her paper is one of about a dozen in a special theme issue focused on acoustics in marine ecology. Van Parijs, who currently heads the NEFSC's Protected Species Branch, is also a co-author of a related paper on acoustic interference or masking, in which marine animals alter their use of sound as a result of changing background noise......... Posted by: Kelly      Read more         Source

December 29, 2009, 8:54 AM CT

An export business that protects cilia

A protein complex mutated in human disease removes excess signaling molecules to prevent them from damaging cilia, say scientists from UMass Medical School. The study would be reported in the December 28 issue of the Journal of Cell Biology (www.jcb.org).

Defective cilia cause a range of diseases including Bardet-Biedl syndrome (BBS), a rare, multi-tissue disorder associated with mutations in 12 different proteins. Seven of these form a complex called the BBSome, but the function of this protein assembly in cilia and flagella is unclear. In worms, the complex glues together the intraflagellar transport (IFT) machinery that assembles and maintains cilia by hauling cargo back and forth along the organelle's microtubules. But most mammalian cell types can still form cilia in the absence of BBS proteins, suggesting that the BBSome isn't essential for IFT.

Lechtreck et al. turned to the green alga Chlamydomonas, and observed that BBS proteins were only present on a subset of IFT particles in each of the alga's two flagella. Strains lacking components of the BBSome showed normal rates of IFT and proper flagellar structure, but couldn't steer away from bright light like wild-type cells could. Mutant flagella accumulated several signaling-related proteins, which the scientists think may disrupt the alga's response to light......... Posted by: Janet      Read more         Source

December 29, 2009, 8:17 AM CT

Insight into evolution of great apes

The timing of molar emergence and its relation to growth and reproduction in apes is being reported by two scientists at Arizona State University's Institute of Human Origins in the Dec. 28 online early edition of the Proceedings of the National Academy of Sciences (PNAS).

From the smallest South American monkeys to the largest African apes, the timing of molar development and eruption is closely attuned to many fundamental aspects of a primate's biology, according to Gary Schwartz, a researcher at the Institute of Human Origins and an associate professor in the School of Human Evolution and Social Change in ASU's College of Liberal Arts and Sciences.

"Knowing the age when the first molar appears in the mouths of most primates allows researchers to predict a host of life history attributes, such as gestation length, age at sexual maturity, birth spacing, and overall lifespan. Humans are unique among primates because our life histories are so slow and thus our molars emerge relatively late. Given that apes are our closest living relatives, understanding the broader context of when the characteristic slower development of humans evolved is of great interest," Schwartz explains.

"We've known quite a bit about the timing of molar development in chimpanzees, which is important because they are our closest living relative. However, we've known virtually nothing about when this important event occurs in other wild-living ape species until now," says lead author Jay Kelley, a research affiliate at ASU's Institute of Human Origins and an associate professor in the Department of Oral Biology at the University of Illinois, Chicago......... Posted by: Kelly      Read more         Source

December 24, 2009, 7:26 AM CT

Whiskers hold secrets of invasive minks

Details of the lifestyle of mink, which escaped from fur farms and now live wild in the UK, have been revealed through analysis of their whiskers. Research led by the University of Exeter reveals more about the diet of this invasive species and provides a clue to its whereabouts. There are now plans to use the findings to eradicate it from environments where it can be devastating to native species.

Reported in the Journal of Applied Ecology, the study focused on American mink living in the Outer Hebrides, Scotland. The researchers used stable isotope analysis to study the whiskers and claws of mink carcasses collected on the islands. This technique generates a kind of unique chemical fingerprint, providing a record of an animal's diet over time. The results showed that the mink had been increasingly reliant on seafood, proving to the researchers that mink had started to move to the coastline around the islands.

Wildlife biologists from the Food and Environment Research Agency have been working to eradicate mink, which escaped from fur farms and now live wild on the Outer Hebrides. Having successfully eradicated mink from two islands Uist and Harris the team now plans to use the research findings to manage populations across the Outer Hebrides. As a result of the study, the team will focus future efforts on coastal regions......... Posted by: Kelly      Read more         Source