July 23, 2007, 6:26 PM CT

Steroids, not songs, spur growth of brain regions in sparrows

Neuroresearchers are attempting to understand if structural changes in the brain are correlation to sensory experience or the performance of learned behavior, and now University of Washington scientists have found evidence that one species of songbird apparently has something in common with a few baseball sluggers. Both rely on steroids, birds to increase the size of song production areas of their brain and some players, apparently, to knock a fastball out of the park.

Writing last month in the Journal of Neuroscience, Eliot Brenowitz and colleagues showed that the Gambels white-crowned sparrow uses testosterone, a naturally occurring steroid, to trigger the seasonal growth of these brain regions. Birds use song to attract mates and mark their territory.

Their finding is counter to some prior work with other birds and rodents that indicated environmental factors can influence brain development and create more neuronal connections.

We would like to believe that if we shape the environment we can guide the brains structure, said Brenowitz, a UW professor of psychology and biology. But the idea that experience can drive growth of the brain regions that control song behavior in birds was disproved by this study. You can change the experience and the behavior, but you dont change the structure of the brain.The UW researchers observed that the three brain regions in white-crowned sparrows that had been deafened were just as large as those regions in normal sparrows. However, the deafened birds only sang one-eighth the number of songs that the hearing birds sang......... Posted by: Kelly      Read more         Source

July 23, 2007, 6:00 PM CT

Limpets reveal possible fate of cold-blooded Antarctic animals

A limpet no bigger than a coin could reveal the possible fate of cold-blooded Antarctic marine animals as per new research published this week in The Journal of Experimental Biology.

In comparison to their temperate and tropical cousins, cold-blooded polar marine animals are incapable of fast growth. Until now researchers assumed that a lack of food in winter was the major limiting factor. Studies of the protein-making abilities of limpets in both the sea around the British Antarctic Surveys (BAS) Rothera Research Station and in the laboratory aquarium reveal that these animals cannot make proteins the building blocks of growth - efficiently.

Lead author Dr Keiron Fraser from BAS says, This is an important step forward in our understanding of the complex biodiversity of Antarcticas unique ecosystem. Sea temperature is predicted to increase by around 2C in the next 100 years. If cold-blooded Antarctic animals cant grow efficiently, or increase their growth rates, they are unlikely to be able to cope in warmer water, or compete with species that will inevitably move into the region as temperatures rise.

Growth in animals occurs primarily by making and retaining proteins. While tropical water limpets typically retain 70% of the proteins they make, those in the Antarctic appear only to retain about 20%......... Posted by: Kelly      Read more         Source

July 23, 2007, 5:09 PM CT

Killing only a few animals won't do any harm - or will it?

Using advanced mathematical modeling, scientists from Sweden and The Netherlands show in an article in the recent issue of the American Naturalist that this statement is sometimes true.

Sometimes though, killing even a few individuals can have dramatic consequences, causing populations to fluctuate wildly. The important question is: who gets killed" The effects of killing individuals crucially depend on the size of the victims, says Tobias van Kooten, assistant professor at Ume University in Sweden. The regulation of populations is commonly determined by the properties of one specific size class of individuals. In some species, this crucial stage consists of small individuals that can monopolize the available food, denying it to all other individuals.Alternatively, particularly in fish populations, large individuals can limit the abundance of smaller individuals through cannibalism. It is when such a crucial size class is the target of mortality that unexpected things may happen. Van Kooten and co-workers predict for example that in harvested cannibalistic fish populations, individuals may reach giant sizes, more than double the size of those in unharvested population. Indeed, such giant cannibals seem to occur frequently in heavily fished lakes. Our results are directly applicable to conservation and management, since almost all human-induced mortality is size-selective, van Kooten states. Fishermen select gear to catch large fish, while deer hunters prefer the tender meat of calves. Unexpected effects of mortality have been reported before, but this systematic study, would be published in The American Naturalist, unravels the mechanisms behind the effects. Such deep understanding makes it possible to predict effects of size-dependent mortality for a wide range of species......... Posted by: Kelly      Read more         Source

July 23, 2007, 4:54 PM CT

Why Humans Walk on Two Legs

A team of anthropologists that studied chimpanzees trained to use treadmills has gathered new evidence suggesting that our earliest apelike ancestors started walking on two legs because it mandatory less energy than getting around on all fours.

"When our earliest ancestors started walking on two legs, they took the first steps toward becoming human," said lead researcher Michael Sockol of UC Davis. "Our findings help answer why".

The research appears this week in the online early edition of the Proceedings of the National Academy of Sciences. It will appear in the July 24 print edition.

"This is the first time anyone has succeeded in studying energetics and biomechanics in adult chimps," said Sockol, who worked for two years to find an animal trainer willing to coax adult chimps to walk on two legs and to "knucklewalk" on all fours on the sort of treadmill found in most gyms. The five chimps also wore face masks used to help the scientists measure oxygen consumption.

While the chimps worked out, the researchers collected metabolic, kinematic and kinetic data that allowed them to calculate which method of locomotion used less energy and why. The team gathered the same information for four adult humans walking on a treadmill.

The scientists observed that human walking used about 75 percent less energy and burned 75 percent fewer calories than quadrupedal and bipedal walking in chimpanzees. They also observed that for some but not all of the chimps, walking on two legs was no more costly than knucklewalking......... Posted by: Kelly      Read more         Source

July 23, 2007, 3:16 PM CT

Fruit fly gene from 'out of nowhere'

Researchers thought that most new genes were formed from existing genes, but Cornell scientists have discovered a gene in some fruit flies that appears to be uncorrelation to other genes in any known genome.

The new gene, called hydra, exists in only a small number of species of Drosophila fruit flies, which suggests it was created about 13 million years ago, when these melanogaster subgroup species diverged from a common ancestor.

And early evidence indicates that the new gene is functional (as opposed to being nonfunctional "junk" DNA) and is likely to express a protein involved in late stages of sperm cell development (spermatogenesis). This finding is consistent with work of other researchers who are discovering that a number of of the most recently formed functional genes in any species also are expressed in male testes and appear correlation to spermatogenesis.

"This is a de novo -- 'out of nowhere' -- gene," said Hsiao-Pei Yang, a senior research associate in Cornell's Department of Molecular Biology and Genetics and senior author of a paper reported in the July 6 issue of the online journal PLoS Genetics (Public Library of Science Genetics). "People used to believe that new genes were always formed from tinkering with other genes, but with this gene we can find no homologues [genes with a similar structure]. You cannot find any related genes in the fly genome or any species' genome, and that is what is unique"......... Posted by: Kelly      Read more         Source

July 19, 2007, 10:38 PM CT

Charting ever-changing genomes

Instead of immutable proprietary software, any species genetic information resembles open source code that is constantly tweaked and optimized to meet the users specific needs. But which parts of the code have withstood the test of time and which parts have undergone rapid evolutionary change has been difficult to assess.

An international collaboration by scientists at the Salk Institute for Biological Studies, the University of Chicago, and the Max-Planck Institute for Developmental Biology developed a simple method to comb whole genomes for all the software fixes and security patches accumulated over time. In a first trial run, the researchers catalogued the genetic variations in 23 strains of the mustard weed Arabidopsis thaliana that were collected from the wild all over the world.

Our study represents one of the first whole genome scans for levels and patterns of genetic variation within a species, says Joseph R. Ecker, Ph.D., professor in the Plant Biology Laboratory and director of the Salk Institute Genomic Analysis Laboratory, who led the current study published in last weeks online edition of the Proceedings of the National Academy of Science. It reveals the regions that are currently targeted by natural selection or have been so during the evolutionary past......... Posted by: Janet      Read more         Source

July 19, 2007, 9:43 PM CT

Ice Age survivors in Iceland

A number of researchers think that the ice ages exterminated all life on land and in freshwater in large parts of the Northern Hemisphere, particularly on ocean islands such as Iceland. Researchers at Holar University College and the University of Iceland have challenged that belief, at least when looking at groundwater animals. They have discovered two species of groundwater amphipods in Iceland that are the only animals species found solely in Iceland. These finding can only be explained by these animals surviving glaciations in some kind of refugium under the glaciers, says Bjarni K. Kristjnsson, the scientist who found the species.

In an article in the recent issue of The American Naturalist, they put forward strong support for their theory. Groundwater amphipods are poor at dispersal, and can not be transported with birds or humans, says Jrundur Svavarsson. One of these new species falls within a new family of amphipods, which indicates that the species has been a long time in Iceland. The time since the end of the last glaciation is not enough for a family to evolve, says Svavarsson. Kristjansson and Svavarsson find it likely that the amphipod came to Iceland as early as 30-40 million years ago, when the volcanic island was being formed. If our theory is right, we have discovered the oldest inhabitants of Iceland, and that can help us further understand how Iceland was formed, says Kristjansson......... Posted by: Kelly      Read more         Source

July 19, 2007, 9:40 PM CT

Probing biology's dark matter

A typical human mouth teems with as a number of as 700 different species of microbes. A handful of these have been specifically implicated in promoting gum disease, dental cavities, and bad breath, but for the most part, the make-up of this complex ecosystem and its impact on human health remain largely unexplored. A new device created by Howard Hughes Medical Institute (HHMI) researchers, however, may make some of the most reclusive members of this and other microscopic communities much more accessible for laboratory study.

The vast majority of microbes are notoriously resistant to growing in laboratory cultures because they are so intricately associated with their own unique ecosystems. Microbiologists have coaxed less than one percent of the bacterial species that inhabit natural environments into growing in culture. But a microfluidics device created by Howard Hughes Medical Institute investigator Stephen R. Quake and his colleagues at Stanford University an intricate system of miniscule valves and chambers -- may help researchers who want to identify and characterize new microbes circumvent the need to culture them at all.

Research on the device reported in the July 9, 2007, issue of the Proceedings of the National Academy of Sciences (PNAS) has far-reaching implications for the rapidly developing field of microbial ecology, as well as advancing microfluidics technologies, which could do for biology what silicon chips did for electronics. Quake and colleagues have already used the device to analyze a rare bacteria found in the human mouth, using just a single cell......... Posted by: Janet      Read more         Source

July 19, 2007, 9:36 PM CT

Mystery Of Wanton Queen Honeybees

Why do queen honeybees mate with dozens of males? Does their extreme promiscuity, perhaps, serve a purpose?

An answer to this age-old mystery is proposed in the July 20 issue of Science magazine by Cornell scientists: Promiscuous queens, they suggest, produce genetically diverse colonies that are far more productive and hardy than genetically uniform colonies produced by monogamous queens.

"An intriguing trait of honeybee species worldwide is that each honeybee queen mates with an extraordinarily high number of males," said Heather R. Mattila, a Cornell postdoctoral fellow in neurobiology and behavior and co-author of the article with Thomas D. Seeley, Cornell professor of neurobiology and behavior.

In every honeybee species, say the researchers, queens mate with multiple males. The European honeybee -- the common species in North America -- mates with from six to 20 mates on average, for example, while the giant honeybee in Asia has a reported record of 102 mates.

To study the reasons for honeybees' promiscuity, the Cornell biologists inseminated 12 queens with sperm from 15 drones (a different set for each) and nine additional queens with sperm from a single drone (but a different one in each case). They then prompted the hives to swarm in early June to form new colonies......... Posted by: Kelly      Read more         Source

July 17, 2007, 10:31 PM CT

Decoding mushroom's secrets

Scientists at the University of Warwick are co-ordinating a global effort to sequence the genome of one of the World's most important mushrooms - Agaricus bisporus. The secrets of its genetic make up could assist the creation of biofuels, support the effort to manage global carbon, and help remove heavy metals from contaminated soils.

The Agaricus mushroom family are highly efficient 'secondary decomposers' of plant material such as leaves and litter -breaking down the material that is too tough for other fungi and bacteria to handle. How exactly it does this, especially how it degrades tough plant material known as lignin, is not fully understood. By sequencing the full genome of the mushroom, scientists hope to uncover exactly which genes are key to this process. That information will be extremely useful to researchers and engineers looking to maximize the decomposition and transformation of plant material into bio fuels.

The mushroom also forms an important model for carbon cycling studies. Carbon is sequestered in soils as plant organic matter. Between 1-2 giga tons of carbon a year are sequestered in pools on land in the temperate and boreal regions of the earth, which represents 15-30% of annual global emissions of carbon from fossil fuels and industrial activities. Understanding the carbon cycling role of these fungi in the forests and other ecosystems is a vital component of optimizing carbon management......... Posted by: Janet      Read more         Source