July 26, 2009, 12:36 AM CT

An 'eye catching' vision discovery

Nearly all species have some ability to detect light. At least three types of cells in the retina allow us to see images or distinguish between night and day. Now, scientists at the Johns Hopkins School of Medicine have discovered in fish yet another type of cell that can sense light and contribute to vision.

Reporting in this week's Nature, the team of neuroresearchers shows that retinal horizontal cells, which are nerve cells once thought only to talk to neighboring nerve cells and not even to the brain, are light sensitive themselves.

"This is mind-boggling," says King-Wai Yau, Ph.D., a professor of neuroscience at the Solomon H. Snyder Department of Neuroscience at Johns Hopkins.

"For more than 100 years, it's been known that rod cells and cone cells are responsible for sensing light, and therefore, vision," says Yau. "Then, about seven years ago, another light sensor was discovered in the retina, revealing a third type of light-sensitive cells in mammals, so we set out to look at whether this was true in other vertebrates as well".

Focusing their efforts on the melanopsin light sensor, which is responsible for sensing day and night but barely involved in mammals, at least in seeing images, Yau's team looked for melanopsin-containing cells in other vertebrates, and found some in the retinal horizontal cells in goldfish and catfish......... Posted by: Kelly      Read more         Source

July 21, 2009, 10:54 PM CT

Horns alone do not make the species

How do you recognize a new species?

A thorough study of the million-year evolution of California's horned lizards, sometimes referred to as "horny toads," shows that when it comes to distinguishing such recently diverged species, the most powerful method integrates genetic, anatomical and ecological information.

In the study, published this week in the early online edition of the journal Proceedings of the National Academy of Sciences, scientists from the University of California, Berkeley, and the U.S. Geological Survey consider all these criteria to show that when the coast horned lizard (Phrynosoma coronatum) moved north from Baja California and spread throughout the state, it diverged into at least two new species.

"When you stack up all the data sets, they all support three species," said main author Adam Leach, a recent UC Berkeley Ph.D. recipient who is now a National Science Foundation bioinformatics postdoctoral fellow at UC Davis. "If you were to pick only one data set, you would get a different number of species. One lesson we learned about the speciation process is that you can't rely on one type of data to accurately track a species' history".

Aside from the oldest and original species, P. coronatum, found only in southern Baja California, the scientists identified a new species, P. cerroense, in central Baja and a third, P. blainvillii, whose range extends from northern Baja to Northern California. Within the third, wide-ranging species, the study's authors found enough genetic and ecological differences to suggest there are at least three distinct populations of P. blainvillii, each requiring separate management and protection......... Posted by: Kelly      Read more         Source

July 20, 2009, 11:53 PM CT

Sea lamprey jettison one-fifth of their genome

Scientists have discovered that the sea lamprey, which emerged from jawless fish first appearing 500 million years ago, dramatically remodels its genome. Shortly after a fertilized lamprey egg divides into several cells, the growing embryo discards millions of units of its DNA.

The findings were published this month in the Proceedings of the National Academy of Sciences The main author is Jeramiah Smith, a postdoctoral fellow in genome sciences at the University of Washington (UW) working in the Benaroya Research Institute laboratory of Chris Amemiya, who is also a UW affiliate professor of iology.

Theirs is thought to bethe first recorded observation of a vertebrate -- an animal with a spinal column -- extensively reorganizing its genome as a normal part of development. A few invertebrate species, like some roundworms, have been shown to undergo extensive genome remodeling. However, stability was believed to be vital in vertebrates' genomes to assure their highly precise, normal functioning. Only slight modifications to allow for immune response were believed to occur in the vertebrate genome, not broad-scale rearrangements.

Smith, Amemiya and their research team inadvertently discovered the dynamic transformations in the sea lamprey genome while studying the genetic origins of its immune system. The scientists were trying to deduce how the sea lamprey employs a copy-and-paste mechanism to generate diverse receptors for detecting a variety of pathogens......... Posted by: Kelly      Read more         Source

July 16, 2009, 11:48 PM CT

Neon blue-tailed tree lizard glides like a feather

Most lacertid lizards are content scurrying in and out of nooks and crannies in walls and between rocks. However, some have opted for an arboreal life style. Neon blue tailed tree lizards (Holaspis guentheri) leap from branch to branch as they scamper through trees in the African forest. There are even anecdotes that the tiny African tree lizards can glide. But without any obvious adaptations to help them to upgrade a leap to a glide, it wasn't clear whether the reptiles really do take to the air and, if they do, how they remain aloft. Intrigued by all aspects of lacertid locomotion, Bieke Vanhooydonck from the University of Antwerp and her colleagues, Anthony Herrel and Peter Aerts, decided to find out whether neon blue tailed tree lizards really glide. Recruiting undergraduate Greet Meulepas to the team, they began filming dainty neon blue tailed tree lizards, gliding geckos (Ptychozoon kuhli) and the common wall lizard (Podarcis muralis) as the animals leapt from a 2m high platform to see if the neon blue tailed tree lizards really could glide. Vanhooydonck and her colleagues publish their discovery that H. guentheri glide like feathers on 17 July 2009 in the Journal of Experimental Biology at http://jeb.biologists.org.

Unfortunately, filming the lizards was extremely difficult. Having startled the small animals into leaping off the platform, the team had little control over the animal's direction, and couldn't guarantee that it was parallel to their camera. It was also difficult to capture each trajectory with a single camera and tricky to get the lighting conditions right. But after weeks of persistence the team finally collected enough film, as the lizards leapt, to compare their performances......... Posted by: Kelly      Read more         Source

July 16, 2009, 11:46 PM CT

Catastrophic winter seabird losses

It's a terrible sight: hundreds of dead seabirds washed up on the seashore. These catastrophic events occur in the winter and are known as winter wrecks. No one knows why the birds perish, and it is almost impossible to study the animals out in stormy winter seas to find out how they meet their fate. With the birds' tough life style in mind, Jrme Fort and David Grmillet from the CNRS Centre d'Ecologie Fonctionnelle et Evolutive in France decided to try to estimate the energetic demands placed on two alcid species (little auks and Brnnich's guillemots) by their aquatic lifestyle to find out whether battling the harsh conditions may simply be too energetically demanding for the little seafarers. Fort and colleagues publish their discovery that winter wreck victims may not be able to eat enough to survive the harsh winter conditions in the Journal of Experimental Biology on 17 July 2009 at http://jeb.biologists.org/.

As it is impossible to gain access to the offshore birds in winter to directly measure their energy requirements, Fort and Gremillet teamed up with Warren Porter, who models the effects of environmental conditions on terrestrial animals, to estimate the birds' metabolic demands. Adjusting Porter's Niche MapperTM computational model to take account of the ocean environment and the birds' physiology, the team included environmental data for two regions of the Atlantic Ocean (off Newfoundland and Greenland) occupied by little auks and Brnnich's guillemots. They also detailed the plumage, physiology and behaviour of individual birds and calculated the animals' metabolic demands for the months from September to March......... Posted by: Kelly      Read more         Source

July 11, 2009, 1:24 PM CT

Scientists from Scotland to Study Bovine TB

In 2008, the U.S. Department of Agriculture spent $31 million to depopulate herds of cattle affected by bovine tuberculosis (TB), even though the risk of the disease has been significantly reduced in the U.S. over the past several decades. Worldwide, particularly in developing countries, the disease persists, which could threaten the U.S. cattle industry in terms of international trade.

The development of new tools to better understand bovine TB and to help disease eradication efforts by the USDA is the focus of a workshop to be held at NIMBioS, July 7-9, on the University of Tennessee, Knoxville, campus.

The workshop brings together experts from around the world to share ideas about how mathematical modeling approaches for cattle movements in the United States may influence disease transmission models as well as inform policies and programs for reducing the spread of bovine TB. Researchers attending the workshop include those with expertise in mathematical network and disease spread models, as well as researchers with expertise in cattle movements, livestock industry practices, and the bovine TB agent.

"NIMBioS is uniquely situated to foster such collaborations because one of its specific priorities is bringing together mathematics and biology scientists to address problems that are important to the animal industry," said Agricola Odoi, workshop co-organizer and an assistant professor in the Department of Comparative Medicine at the University of Tennessee School of Veterinary Medicine......... Posted by: Kelly      Read more         Source

July 6, 2009, 7:48 PM CT

Learning more about big birds from feathers

Catching adult eagles for research purposes is no easy task, but a Purdue University researcher has found a way around the problem, and, in the process, gathered even more information about the birds without ever laying a hand on one.

"A number of birds are small, easy to catch and abundant," said Andrew DeWoody, associate professor of forestry and natural resources. "With eagles, the effort can be 100 to 1,000 times greater than catching chickadees."

Eagles can be hard to find, they often require live bait to attract and, with sharp talons and beaks capable of snapping off human fingers, they pose a risk to their would-be captors.

Instead of catching eagles, DeWoody collects their feathers and uses the small amount of DNA in them to create a tag that corresponds to a particular bird. Those tags can be used to determine population, parentage, roosting patterns and sex ratio.

"In an afternoon, you can go out and pick up hundreds of feathers," DeWoody said, "As field work goes, it's about as easy as it gets".

DeWoody's method is described in a chapter of the Handbook of Nature Conservation: Global and Economic Issues, which was released this week. The chapter is a compilation of his research on the topic.

Most birds are studied by catching them in nets and attaching tracking devices. Scientists can then follow the birds and use radio technology to triangulate their locations......... Posted by: Kelly      Read more         Source

July 4, 2009, 10:52 PM CT

A question of height

Intelligent countryside management could improve the survival chances of animal and plant species threatened by climate change. The creation of small heat-shielded habitats and better links between habitats would counteract a moderate temperature increase and give threatened species more time to adapt better and/or to migrate to cooler regions. This is the conclusion drawn by researchers at the Helmholtz Centre for Environmental Research (UFZ) from a British study on saving the Large Blue butterfly (Maculinea arion). This butterfly became extinct in Britain in 1979 and was reintroduced there 25 years ago. Since then, the butterfly's reintroduction is seen as a model for the conservation of endangered insects. A form of countryside management that creates cooler microclimatic conditions, for example through taller grass in today's meadows, should mitigate the effects of global warming in the short and medium term, say the researchers, writing in the current issue of Science This is, however, not a long-term solution just a stop-gap for the next few decades.

The Large Blue butterfly (Maculinea arion) is rather rare throughout a number of European countries. It is found in meadows and pastures where thyme grows because the caterpillars eat only this plant or its close relative, wild marjoram (Origanum vulgare). The butterfly's survival depends on a large number of factors - as it belongs to the genus Maculinea. This means that it is dependent not only on a specific food plant for the caterpillars, but also on a particular species of ant. The caterpillars trick the ants into carrying them into their nest where they feed on the ants' brood through the winter. However, this trick works only on one very specific type of ant only Myrmica sabuleti is tricked by the scent of the caterpillars' of the Large Blue. Other ants see through the disguise and remove any caterpillars that have been carried into their nest. During the decline of the Large Blue in Britain, M. sabuleti ants were crowded out by a competing species of ant, M. scabrinoides, which copes better with lower soil temperatures. "A change in the height of the grass by one or two centimetres can result in a two or three degree temperature change in the ants' brood chambers just below the surface," explains Prof. Jeremy A. Thomas of Oxford University. The biologist spent decades studying the complicated interplay and his findings have now been reported in the same issue of Science - in a publication to which the Helmholtz researchers refer. The soil temperature dropped because the meadows on which the butterflies and ants had lived together for so long were grazed less, and because an epidemic among the wild rabbits, which used to keep the grass short, caused their numbers to plummet. A change in land use had thrown the sensitive interplay between the species off balance. By the time this was realised, it was already too late for the Large Blue in Britain. Once the precise reasons for the disappearance of the butterfly populations became known, researchers kept a lookout for suitable donor populations in other European countries so that the butterfly could be reintroduced. Eventually, butterflies were brought in from Sweden and the meadows were kept short in line with the scientific findings. It was this that turned the reintroduction of the Large Blue into a success story. There are now more butterflies of this highly endangered species living in the UK than there were when records began in the 1950s. "The fact that it was possible to stop and reverse the decline could make this a model for a number of other insect conservation projects," hopes Jeremy Thomas......... Posted by: Kelly      Read more         Source

July 4, 2009, 10:48 PM CT

Hair sheep, could be key to better diagnostic tests

It's the hair sheep, a less-hirsute version of the familiar woolly barnyard resident. A newly released study from the Stanford University School of Medicine, which is to be published July 3 in PLoS ONE, finds that not only are these ruminants low-maintenance and parasite-resistant, they're also perfect blood donors for the microbiology tests necessary to diagnose infectious disease in the developing world.

Identifying microbes from a patient's urine or sputum requires growing those microbes in culture dishes filled with gelatinous agar and a small amount of blood. The blood provides nutrients to the growing bugs and also provides clues as to the microbes' identities: Microbiologists can rule out or identify certain strains of bacteria based on how the organisms interact with the blood cells in culture.

In the developed world, microbiologists use sheep or horse blood. But in a number of parts of the developing world, horses are prohibitively expensive, and regular sheep, with their constant need for shearing and tendency to get infections, are difficult to keep alive. Importing animal blood isn't feasible either, as shipping is costly and often unreliable.

A number of labs in the developing world use human blood, often donated by lab technicians themselves. But diagnostic tests aren't standardized for human blood, said Ellen Yeh, MD, a resident in pathology at Stanford and first author on the paper. "You don't get the same test results when you use human blood versus sheep blood," she said. In addition, the use of human donors increases technicians' risk of infection with blood-borne diseases......... Posted by: Kelly      Read more         Source

July 2, 2009, 10:05 PM CT

Learning from locusts

A similarity in brain disturbance between insects and people suffering from migraines, stroke and epilepsy points the way toward new drug therapies to address these conditions.

Queen's University biologists studying the locust have observed that these human disorders are linked by a brain disturbance during which nerve cells shut down. This also occurs in locusts when they go into a coma after exposure to extreme conditions such as high temperatures or lack of oxygen.

The Queen's study shows that the ability of the insects to resist entering the coma, and the speed of their recovery, can be manipulated using drugs that target one of the cellular signaling pathways in the brain.

"This suggests that similar therapys in humans might be able to modify the thresholds or severity of migraine and stroke," says Gary Armstrong, who is completing his PhD research in Biology professor Mel Robertson's laboratory. "What especially excites me is that in one of our locust models, inhibition of the targeted pathway completely suppresses the brain disturbance in 70 per cent of animals," adds Dr. Robertson.

The Queen's research team previously demonstrated that locusts go into a coma as a way of shutting down and conserving energy when conditions are dangerous. The cellular responses in the locust are similar to the response of brain cells at the onset of a migraine......... Posted by: Kelly      Read more         Source