February 5, 2007, 7:35 PM CT

Protein Sorting With A New Microchip

A new MIT microchip system promises to speed up the separation and sorting of biomolecules such as proteins. The work is important because it could help researchers better detect certain molecules linked to diseases, potentially leading to earlier diagnoses or therapys.

The microchip system has an extremely tiny sieve structure built into it that can sort through continuous streams of biological fluids and separate proteins accurately by size. Conventional separation methods employ gels, which are slower and more labor-intensive to process. The new microchip system could sort proteins in minutes, as in comparison to the hours necessary for gel-based systems.

The MIT team's results appear in the Feb. 5 issue of Nature Nanotechnology.

The new technology is an advance from a one-dimensional sieve structure reported by the same MIT group last year. The key to this new advance, called an anisotropic nanofluidic sieving structure, is that the scientists have designed the anisotropic sieve in two orthogonal dimensions (at a right angle), which enables rapid continuous-flow separation of the biological sample. This allows continuous isolation and harvesting of subsets of biomolecules that scientists want to study. And that increases the probability of detecting even the smallest number of molecules in the sample.........

Posted by: Janet      Read more         Source

February 5, 2007, 6:41 PM CT

Keeing Fish Out Of Hot Water

Right now some tubeworm tartare and clams on the half shell would really hit the spot, so you're headed for the all-night caf.

"All-night" being the operative word because the volcanic ridge you're tooling along is nearly 1.5 miles below the surface. The term "where the sun don't shine" perfectly describes the place. It's pitch black.

Darn, but what's that loud rumbling up ahead?

Must be one of those pesky black smokers. Some of those babies can fry your face off. A detour is highly indicated.

The long-held assumption that black smokers are silent is wrong, as per recently published research led by Timothy Crone, a University of Washington doctoral student in oceanography. It's prompting researchers to wonder: Could the sound and vibrations of black smokers be the reason fish in total darkness avoid being poached by waters as hot as 750 F? And might similar sounds guide them to the smorgasbord of tube worms, mussels, shrimp, snails and other fauna at vents with more temperate waters?

Want to be the first on your block to hear what a black smoker sounds like?

The research was reported online during the inaugural month of the Public Library of Sciences' interactive journal, PLoS ONE. Aimed at involving more people in science, published results are available without a subscription and can include a wealth of audio, video and other materials.........

Posted by: Kelly      Read more         Source

February 2, 2007, 4:37 AM CT

Algae Toxin And The Fish-kill Mystery

A team of scientists from the Hollings Marine Laboratory in Charleston, S.C., has uncovered a subtle chemical pathway by which normally inoffensive algae, Pfiesteria piscicida, can suddenly start producing a lethal toxin. The discovery, reported last week in Environmental Science and Technology,* could resolve a long-standing mystery surrounding occasional mass fish kills on the East Coast.

Pfiesteria has been implicated for years in a series of otherwise unexplained episodes of mass fish death throughout its range from roughly Delaware to Alabama, especially in the Neuse River in North Carolina and the Chesapeake Bay. The single-cell organism can experience explosive growth resulting in algae blooms in coastal waters. While it has been suspected not only in fish kills but in incidents of human memory loss and other environmental and health-related effects, no one has ever conclusively identified the actual mechanism. Attempts to grow lethal Pfiesteria in the laboratory have had inconsistent results.

The Hollings Marine Laboratory is a joint institution of the National Oceanic and Atmospheric Administration (NOAA), the National Institute of Standards and Technology (NIST), the South Carolina Department of Natural Resources, the College of Charleston, and the Medical University of South Carolina (MUSC). Lead researcher Peter Moeller of NOAA suspected that the presence or absence of heavy metals might be the missing factor accounting for Pfiesteria's lethality, and put together a multidisciplinary research team to identify the actual toxin and the conditions under which it is produced.........

Posted by: Kelly      Read more         Source

January 31, 2007, 9:10 PM CT

'Electric' Fish Shows How Brain Directs Movement

Researchers have long struggled to figure out how the brain guides the complex movement of our limbs, from the graceful leaps of ballerinas to the simple everyday act of picking up a cup of coffee. Using tools from robotics and neuroscience, two Johns Hopkins University scientists have found some tantalizing clues in an unlikely mode of motion: the undulations of tropical fish.

Their findings, reported in the January 31 issue of the Journal of Neuroscience, shed new light on the communication that takes place between the brain and body. The fish research may contribute to important medical advances in humans, including better prosthetic limbs and improved rehabilitative techniques for people suffering from strokes, cerebral palsy and other debilitating conditions.

"All animals, including humans, must continually make adjustments as they walk, run, fly or swim through the environment. These adjustments are based on feedback from thousands of sense organs all over the body, providing vision, touch, hearing and so on. Understanding how the brain processes this overwhelming amount of information is crucial if we want to help people overcome pathologies," said Noah Cowan, an assistant professor of mechanical engineering in Johns Hopkins' Whiting School of Engineering. In studying the fish and preparing the Neuroscience paper, Cowan teamed up with Eric Fortune, assistant professor of psychological and brain sciences in the Krieger School of Arts and Sciences, also at Johns Hopkins.........

Posted by: Kelly      Read more         Source

January 31, 2007, 8:45 PM CT

First Endangered Fish Species Recovers

For the first time in U.S., and probably global, history a fish identified as endangered has been shown to have recovered -- and in the Hudson River, which flows through one of the world's largest population centers, New York City.

The population of shortnose sturgeon, which lives in large rivers and estuaries along the Atlantic coast of North America, has increased by more than 400 percent in the Hudson River since the 1970s, report Mark Bain, associate professor of natural resources at Cornell, and colleagues in the online publication PLoS ONE. However, the shortnose sturgeon is still endangered in other rivers, Bain said, and will not necessarily be removed from the endangered species list by the U.S. government.

In the past 100 years, 27 species of fish have died out in North America and four have become extinct. The U.S. government currently protects 149 fish species and subspecies and a total of 1,311 species under the U.S. Endangered Species Act.

"Endangered and threatened U.S. fish outnumber mammals, reptiles, birds, etcetera," said Bain. Since 1966 when the federal government started identifying threatened species, only 16, including the American alligator, American peregrine falcon and brown pelican, have recovered. "Recovery is very rare," said Bain, who has been monitoring the shortnose sturgeon's population since the mid-1990s and has access to data on the populations since the 1970s.........

Posted by: Kelly      Read more         Source

January 30, 2007, 7:35 PM CT

Molecular Motors and Brakes

Scientists at the University of Pennsylvania School of Medicine have discovered that microtubules - components responsible for shape, movement, and replication within cells - use proteins that act as molecular motors and brakes to organize into their correct structure. If microtubules are not formed properly such basic functions as cell division and transport can go wrong, which may have implications in such disease processes as cancer and dementia. The study, reported in the recent issue of Cell, is featured on the cover of that issue.

"Up until now motors and brakes were studied separately from microtubules," says senior author Phong Tran, PhD, Assistant Professor of Cell and Developmental Biology. "This study lets us have a more complete picture".

Microtubules are structures that help give shape to a number of types of cells, form the spindle (view video below) - a structure important in cell division - and act as a railroad, of sorts, upon which molecular motors move protein packages for waste removal and nerve transmission.

In the Cell study, the investigators, working with fission yeast cells, showed that stable end-to-end arrays of microtubules can be achieved by a balance between the sliding by a molecular motor called klp2p and the braking of a microtubule-associated protein (MAP) called ase1p. Specifically, they showed that a preexisting "mother" microtubule acts as a platform on which a new microtubule can be formed (view video below). The new "daughter" microtubule grows and moves along the mother microtubule. In time, the daughter grows beyond the end of the mother to ultimately produce two microtubules, connected by the cross-linking MAP ase1p.........

Posted by: Janet      Read more         Source

January 30, 2007, 6:35 PM CT

Non-venomous Asian Snakes 'Borrow' Defensive Poison

Most snakes are born with poisonous bites they use for defense. But what can non-poisonous snakes do to ward off predators?

What if they could borrow a dose of poison by eating toxic toads, then recycling the toxins?

That's exactly what happens in the relationship between an Asian snake and a species of toad, according to a team of researchers funded by the National Science Foundation (NSF) Division of Integrative Organismal Systems (IOS).

Herpetologists Deborah Hutchinson, Alan Savitzky of Old Dominion University in Norfolk, Va., and colleagues published results of research on the snake's dependence on certain toads in this week's online issue of the journal Proceedings of the National Academy of Sciences.

Hutchinson studied the Asian snake Rhabdophis tigrinus and its relationship to a species of toxic toad it eats. In the PNAS paper, she and co-authors describe dietary sequestration of toxins by the snakes. The process allows the snakes to store toxins from the toads in their neck glands. When under attack, the snakes re-release the poisons from these neck glands.

Many invertebrates sequester dietary toxins for use in defense, including milkweed insects and sea slugs. But vertebrate examples of toxin sequestration, especially from vertebrate prey, are rare. "A snake that's dependent on a diet of toads for chemical defense is highly unusual," said Hutchinson.........

Posted by: Kelly      Read more         Source

January 30, 2007, 5:14 AM CT

Human Preference For Other Species

As humans exert ever-greater influence on the Earth, their preferences will play a substantial role in determining which other species survive. New research shows that, in some cases, those preferences could be governed by factors as subtle as small color highlights a creature displays.

In the case of penguins, mostly black-and-white flightless birds that live predominantly in the Southern Hemisphere, those most popular with humans appear to be the ones that display markings of warm colors such as red, orange or intense yellow, said David Stokes, a conservation biologist at the University of Washington, Bothell.

He and his undergraduate students calculated the popularity of various species by studying photographs in four large-format photograph books about penguins. Decisions about how a number of and which photographs to use and how large to make them presumably were made by the books' editors based on their own preferences or on their beliefs of what would appeal to the book-buying public.

"Penguins are lucky because they are popular with people, particularly right now. But that's not true of 99.9 percent of the species out there," Stokes said. "Even the penguin species I found to be among the least appealing to people are tourist attractions".

Tops on the list are the Emperors, featured in the film "March of the Penguins," and their close cousins the King penguins. Second are crested penguins, including Rockhoppers and Macaroni.........

Posted by: Kelly      Read more         Source

January 29, 2007, 8:57 PM CT

Why Are Males Larger Than Females?

Why are males larger than females in some animal species (such as most mammals), females larger than males in others (such as most insects), and why are the sexes alike in yet other species (such as several birds)? Further, how is such sexual size dimorphism achieved when it exists? If males and females grow at the same rate, then the larger sex has to extend its growth period. Alternatively, the larger sex can grow faster.

A group of 13 scientists from 10 countries investigated the latter questions using comparative data on 155 species of insects and spiders (arthropods) from 7 major groups. The results, reported in the recent issue of The American Naturalist, suggest that, generally, growth rate differences between the sexes are more important than growth period differences in mediating size dimorphism in arthropods. Nevertheless, depending on the species group, males and females tend to have equal growth periods (beetles and water striders), males have longer growth periods than females (two groups of flies), or males have shorter growth periods than females (so-called protandry), albeit not quite in proportion to the size difference between the sexes (spiders, butterflies, and Hymenoptera, i.e. bees, ants, wasps, and alike).

As in most arthropod groups females are larger, they must therefore generally grow faster, an interesting pattern markedly different from primates and birds, which were also analyzed and in which differences in growth period between the sexes were generally more dominant. Three potential explanations for why female arthropods can grow faster than males are discussed. The most intriguing of these explanations is that, eventhough it is generally cheaper to produce (small) sperm than (large) eggs, it may be costlier to produce male gonads and genitalia than it is to produce female gonads and genitalia. As a result, males might need more time to mature at larger body sizes.........

Posted by: Kelly      Read more         Source

January 26, 2007, 5:10 AM CT

Genetically Modified Crops On Developing Countries

A new study in the recent issue of Current Anthropology explores how the arrival of genetically modified crops affects farmers in developing countries. Glenn Davis Stone (Washington University) studied the Warangal District of Andhra Pradesh in India, a key cotton growing area notorious for suicides by cotton farmers. In 2003 to 2005, market share of "Bt cotton" seeds rose from 12 percent to 62 percent in Warangal. Bt cotton is genetically modified to produce its own insecticide and has been claimed by its manufacturer as the fastest-adopted agricultural technology in history.

Monsato, the firm behind Bt cotton, has interpreted the rapid spread of the modified strain as the result of farmer experimentation and management skill - similar to mechanisms that scholars cite to explain the spread of hybrid corn across American farms. But Stone's multiyear ethnography of Warangal cotton farmers shows an unexpected pattern of localized cotton seed fads in the district. He argues that, rather than a case of careful assessment and adoption, Warangal is plagued by a severe breakdown of the "skilling" process by which farmers normally hone their management practices.

"Warangal cotton farming offers a case study in 'agricultural deskilling'," writes Stone. The seed fads had virtually no environmental basis, and farmers generally lacked recognition of what was actually being planted, a striking contrast to highly strategic seed selection processes in areas where technological change is learned and gradual. Interviews also provided consistent evidence that Warangal cotton farmers prefer trying new seeds - seeds without any background information whatsoever - to trying several strains on smaller, experimental scales and choosing one for long-term adoption.........

Posted by: Erica      Read more         Source