March 11, 2008, 9:53 PM CT

Female katydids' mates

Katydid (or didnt she?) respond to the mating call of her suitors. As per researchers at the University of Missouri, one species of katydid may owe its ecological success and expanded habitat range to the ability of male katydids to adjust their mating calls to attract females.

Males of the katydid species Neoconocephalus triops, which can be found from Peru to Missouri, produce calls to attract females for mating that change with the seasons. The males summer calls are much faster than their winter calls. Johannes Schul, MU associate professor of biological sciences, observed that females were attracted only by a specific speed of the calls and this preference changed with temperature.

Warm females preferred much faster calls than cold females, Schul said. The fast summer calls attracted females only at high temperatures and the slow winter calls only at lower temperatures. Thus, during the winter, females prefer cool guys, and in the summer they like them hot.

As per Schul, male calls exhibit substantial flexibility. At equal temperatures, summer males, or those that mature during the summer, produce calls with a higher pulse rate than winter males, or those that mature in late winter/early spring. The research team tested the katydids preferences by placing females on a spherical treadmill and tracking the speed and accuracy of their responses to recordings of male calls......... Posted by: Kelly      Read more         Source

March 11, 2008, 5:28 AM CT

Mystery behind the strongest creature in the world

The strongest creature in the world, the Hercules Beetle, has a colour-changing trick that researchers have long sought to understand. Research published recently, Tuesday, 11 March, in the New Journal of Physics, details an investigation into the structure of the species peculiar protective shell which could aid design of intelligent materials.

The Hercules Beetle is remarkable, not only for its strength, able to carry up to 850 times its own weight, the protective outgrowth of the insects exoskeleton, aka its shell, also changes from green to black as its surrounding atmosphere gets more humid.

Scientists from the University of Namur in Belgium have used the latest imaging techniques to study the shell of the beetle - a scanning electronic microscope to determine the structure responsible for the colour and a spectrophotometer to analyze how the light interacts with this structure.

The light interferes with the structure to produce the green colour of the shell. When water penetrates through the widely-open porous layers, it destroys the interferences phenomenon leading to a black colouration.

The scientists used dry specimen of the beetles shell to test in laboratory conditions.

The beetle, commonly found in the rainforests of Columbia, Venezuela, Peru, Ecuador, Bolivia, and Brazil, is still rather mysterious though. As eventhough dry specimen of the shell could be relied on to change when humid conditions were introduced, the living specie that scientists also had in the lab were not as consistent......... Posted by: Kelly      Read more         Source

March 9, 2008, 6:02 PM CT

Wandering Albatrosses Follow Their Nose

The first study of how individual wandering albatrosses find food shows that the birds rely heavily on their sense of smell. The birds can pick up a scent from several miles away, U.S. and French scientists have found.

"This is the first time anyone has looked at the odor-tracking behavior of individual birds in the wild using remote techniques," said Gabrielle Nevitt, professor of neurobiology, physiology and behavior at UC Davis and an author on the study with UC Davis graduate student Marcel Losekoot of the Bodega Marine Laboratory and Henri Weimerskirch of the Centre National de la Recherche Scientifique, France.

Wandering albatrosses fly for thousands of miles across the ocean, commonly gliding a few feet above sea level. Floating carrion, particularly squid, make up a large part of their diet.

Albatrosses nesting on Possession Island in the southwestern Indian Ocean were fitted with GPS receivers that recorded their exact position every 10 seconds and stomach temperature gauges that noted every meal. When the birds returned to land after a foraging trip, the scientists removed the equipment and downloaded the data.

They observed that the birds commonly flew across the wind, which allows them to cross plumes of scent drifting downwind and is also the best strategy for energy-efficient soaring......... Posted by: Kelly      Read more         Source

March 9, 2008, 5:23 PM CT

Protective Role Of MicroRNA

Snippets of genetic material that have been associated with cancer also play a critical role in normal embryonic development in mice, as per a new paper from MIT cancer biologists.

The work, published in the March 7 issue of Cell, shows that a family of microRNAs--short strands of genetic material--protect mouse cells during development and allow them to grow normally. But that protective role could backfire: The scientists theorize that when these microRNAs become overactive, they can help keep alive cancer cells that should otherwise die--providing another reason to target microRNAs as a therapy for cancer.

Discovered only a decade ago, microRNAs bind to messenger RNAs (mRNAs), preventing them from delivering protein assembly instructions, thereby inhibiting gene expression. The details of how microRNAs act are still not fully understood.

"The scientific community is busy trying to understand what specific biological functions these microRNAs affect," said Andrea Ventura, lead author of the paper and postdoctoral associate in the Koch Institute for Integrative Cancer Research at MIT (formerly known as the Center for Cancer Research).

Ventura--who works in the laboratory of Tyler Jacks, director of the Koch Institute--and her colleagues studied the function of a family of microRNAs known as the miR-17~92 cluster......... Posted by: Janet      Read more         Source

March 9, 2008, 5:14 PM CT

Signaling pathway for better biofuel sources

A newly defined biochemical pathway in plants may provide the scientific tools to design plants that will yield larger quantities of alternative transportation fuels than currently can be produced, as per Purdue University researchers.

The pathway moves materials that determine cell shape and size through a system of signaling proteins, said Dan Szymanski, a plant geneticist and cellular biologist. By learning more about the growth and development process, it may be possible to engineer plants with improved properties such as cell walls that are more massive or are more easily fermented in the biofuel process.

"We expect that cell wall material will be a major source of biomass from plants designated for biofuel production," Szymanski said. "We need to learn more about how plant cells control the quality and amount of cell wall material".

He and his research team investigated plant growth and cell wall development from several scientific approaches in determining the cascade of events that leads to changes in the cell wall. They discovered that a protein called "SPIKE1" directs the protein signaling pathway. They report their findings in "Early Edition," the online publication of the journal Proceedings of the National Academy of Sciences. The study also would be reported in the journal's March 11 print issue......... Posted by: Erica      Read more         Source

March 9, 2008, 4:39 PM CT

Why pears may become brown during commercial storage

Internal browning of pears stored under low oxygen conditions is correlation to restricted gas exchange inside the fruit, as per a research studypublished March 7th in the open-access journal PLoS Computational Biology. Scientists at the Catholic University of Leuven in Belgium suggest a computer model that can be used to improve long-term storage of fruit under controlled atmospheres.

Pears and other fleshy fruit are commercially stored under low oxygen conditions to extend their storage life for up to 9 months. If the oxygen concentration in the storage atmosphere is too low, quality disorders such as internal browning may result, causing major economic losses. This disorder is known to be correlation to the complex mechanisms of gas exchange, respiration and fermentation in fruit. However, further conclusions are unavailable due to the lack of reliable methods to measure gas concentrations inside the fruit.

The team, led by Bart Nicola, has developed a comprehensive computer model to predict the oxygen concentration inside the pear. The model incorporates equations for gas transport as well as for the respiratory metabolism. The scientists observed that extremely low oxygen concentrations can occur in the core of the pear, which eventually may lead to cell death and browning......... Posted by: Erica      Read more         Source

March 9, 2008, 4:34 PM CT

Photograph depicts wolverine in California

Forest Service scientists believe an Oregon State University graduate student working on a cooperative project with the agencys Pacific Southwest Research station on the Tahoe National Forest has photographed a wolverine, an animal whose presence has not been confirmed in California since the 1920s.

Katie Moriarty, a wildlife biology student, was conducting research on another carnivore called the American marten when a remote-controlled camera she set photographed the animal on February 28, 2008. Forest Service scientists who are experts at detecting rare carnivores believe the photographed animal is a wolverine.

The North American wolverine is the largest member of the weasel family. Adult males weigh 26 to 40 pounds, while females are 17 to 26 pounds. It resembles a small bear, with a bushy tail and broad head. Its diet includes carrion, small animals, birds, insects and berries.

U.S. populations are found largely in the Northern Cascades in Washington, and Northern Rockies in Montana and Idaho. The nearest known resident population is about 900 miles north of the Tahoe National Forest in Northern Washington.

Attempts have been made for decades to photograph wolverines in California, according to Bill Zielinski, a Forest Service scientist with the Pacific Southwest Research Station and an expert at detecting wolverines, marten and fisher. He said periodic sightings have occurred, but never scientifically confirmed using detection methods that produce verifiable evidence......... Posted by: Kelly      Read more         Source

March 7, 2008, 5:23 AM CT

Stevens chemists identify compounds to lure nutria

A 10-pound rodent pest called nutria ravaging southern wetlands in the US, which has been particularly damaging to the marshland ecology in the Mississippi Delta following Hurricanes Rita and Katrina, may have finally met its match thanks to molecular science that includes the work of Professor Athula B. Attygalle, an expert in molecular chemistry and mass-spectrometry based at Stevens Institute of Technology in Hoboken, New Jersey, and a team of researchers from Cornell University and University of Iowa.

The biology of the nutria species allows it to reproduce at rapid speed, making it an unwieldy animal to control if released into the wild. A female nutria averages about five young per litter, but can birth as a number of as 13 at a time. A female can breed again within two days after giving birth, meaning one nutria can have up to three litters per year.

To get a sense of their productivity, 20 nutria brought to Louisiana in the 1930s bred an estimated 20 million animals within two decades, as per a wildlife group in Maryland that tracks nutria data, quoted in a recent report by Louisiana journalist Chris Kirkham.

Eventhough nutria were brought to all parts of the country, said Kirkhams report , warm weather in Louisiana has boosted their numbers. Already under pressure from saltwater intrusion, the marshes also have to deal with the nutria and their voracious appetite for the vital marsh roots that keep wetlands intact......... Posted by: Kelly      Read more         Source

March 5, 2008, 8:54 PM CT

Killer freeze of '07 illustrates paradoxes of warming climate

A destructive spring freeze that chilled the eastern United States almost a year ago illustrates the threat a warming climate poses to plants and crops, as per a paper just reported in the journal BioScience. The study was led by a team from the Department of Energy's Oak Ridge National Laboratory.

The "Easter freeze" of April 5-9, 2007, blew in on an ill wind. Plants had been sending out young and tender sprouts two to three weeks earlier than normal during an uncommonly warm March. Plant ecologists, as well as farmers and gardeners, took note of the especially harsh turn of the weather in early April.

"The warm weather was as much a culprit for the damage as the cold," said lead author Lianhong Gu of ORNL's Environmental Sciences Division.

"We see the paradox in that mild winters and warm, early springs make the plants especially vulnerable to late-season frosts," Gu said. Gu's team observed satellite images and field data to establish the extent of the 2007 spring freeze. They also assessed the long-term and short-term effects on the terrestrial carbon cycle with respect to plant activity in normal years. Short-term effects were "profound," Gu said.

"In the period just after the freeze we saw a large reduction in the fraction of absorbed photosynthetically active radiation, which is a sensitive indicator of plant growth," he said. "We also noted that the regrowth in the following weeks and months did not result in the levels of plant development in prior years."........ Posted by: Erica      Read more         Source

March 5, 2008, 8:19 PM CT

Rats' Twitchy Whiskers In Action

Rats use their whiskers in a way that is closely correlation to the human sense of touch: Just as humans move their fingertips across a surface to perceive shapes and textures, rats twitch their whiskers to achieve the same goal. Now, in a finding that could help further understanding of perception across species, MIT neuroresearchers have used high-speed video to reveal rat whiskers in action and show the tiny movements that underlie the rat's perception of its tactile environment.

Rats rely on whiskers to find their way in the dark, and they devote large areas of their brains to decoding the incoming signals, explains Christopher Moore, a member of the McGovern Institute for Brain Research at MIT and senior author of a study in the February 28th issue of Neuron. Neuroresearchers interested in perception have studied the whisker system intensively, but the information conveyed to the brain by whisker motions has remained a mystery--until now.

"Now that we can see what the rat's whiskers are telling the brain, we can start to understand better how this amazing perceptual system works," says Moore, who is also an assistant professor in MIT's Department of Brain and Cognitive Sciences. "This understanding is relevant not only to the human sense of touch, but to all forms of perception, because every sensory organ is an interface between the mind and the external world"......... Posted by: Kelly      Read more         Source