December 6, 2007, 3:17 PM CT

Tiny pest-eating insect fights fruit flies

Farmers and vineyard owners have a new weapon in their pest management arsenal. A usually used parasitoid, or parasitic insect that kills its host, has proven to be quite effective in the control of fruit flies in vineyards. These tiny pest-devouring insects are considered to be powerful "biocontrol agents" since they reduce the need for chemical pest management applications.

Jean Pierre Kapongo, Ph.D., an entomologist specializing in environmental health at the University of Guelph in Ontario, Canada, recently published the results of a research study that will aid vintners and fruit farmers in their ability to produce healthier crops. As per Kapongo, vineyard owners and farmers can now control fruit flies (Ceratitis capitata) with Muscidifurax raptor, an insect currently used in the control of other types of pests.

The study investigated the use of Muscidifurax raptor to control fruit flies in vineyards. Until recently, fruit flies were commonly controlled with chemical insecticides and selected natural enemies. Kapongo explained that these traditional control methods were not popular with farmers because of the adverse effects of chemicals and the unreliability of using living parasites. "Now we have discovered a parasitoid that is easily produced and effective in controlling fruit flies.", Kapongo commented. He added that insectaries, where parasitic insects are commercially produced and sold, are ready to increase production of the insects in response to market demands from vineyard owners......... Posted by: Kelly      Read more         Source

December 4, 2007, 10:24 PM CT

Can fruit flies help treat stroke?

Reperfusion injury takes place when an animal or an organ is starved of oxygen, then exposed to oxygen again. This occurs in strokes and organ transplants and causes a number of deaths per year. Now researchers at UNLV, Sable Systems International and UCSD have discovered that reperfusion injury can be induced in fruit-flies, a convenient, cheap, well-characterized model animal. The research paper describing their results will be published in PLoS ONE.

With this new model, scientists can explore the mechanisms of reperfusion injury with a classic animal model thats much cheaper and easier to use than vertebrates such as mammals, said Dr. John Lighton, an adjunct professor at UNLV, president of Sable Systems International (a Nevada based company that manufactures precision respirometry systems) and lead scientist. Dr. Pablo Schilman, a physiologist at UCSD, co-authored the research. Use of this method creates a window into the cells' mitochondria. Using Drosophila as a model may mean faster progress in mitigating the human toll of reperfusion injury, which we still dont fully understand. And what we dont fully understand, we cant treat effectively.

The study, which was funded by Sable Systems Internationals Basic Research Initiative and took place in Sable Systems respirometry laboratory in Las Vegas, started out with the first detailed metabolic examination of the fruit-flys ability to survive a complete lack of oxygen for an hour or more. By accident, explains Dr. Lighton, we discovered that exposing fruit-flies to one or more brief bursts of oxygen while they were otherwise oxygen-starved, injured their respiratory systems irreversibly classic reperfusion injury......... Posted by: Kelly      Read more         Source

December 3, 2007, 10:30 PM CT

Origin of Piranha

Piranhas inhabit exclusively the fresh waters of South America. Their geographical distribution extends from the Orinoco River basin (Venezuela) to the North, down to that of the Paran (Argentina) to the South. Over this whole area, which also embraces the entire Amazon Basin, biologists have recorded 28 carnivorous species of these fish (2). In spite of the evolutionary success of this subfamily of fish, the mechanisms that generated the species richness of this group are still insufficiently known.

A team from the IRD, working in partnership with Bolivian and Peruvian scientists, aimed to establish how these species were able to evolve over the past 15 million years. They consequently took samples from around their whole distribution range. Between September 2002 and June 2003, numerous specimens of piranhas were collected from the Bolivian part of the Amazon. Complementary sampling was then conducted in the Brazilian and Peruvian sectors, from the Orinoco in Venezuela, and the So Francisco and the Paran-Paraguay in Brazil. The team selected 57 specimens representative of 21 different species of piranhas, from 15 collection points distributed over the whole South-American hydrographic network,.

Mitochondrial DNA (mtDNA) of piranhas has a especially high mutation rate and thus could be used as a molecular basis for reconstructing the evolution of the present-day species which are different yet very close to one another. These techniques using mtDNA sequences led to the conclusion that the origin of the piranha species inhabiting the rivers of South America today dates back to some ancestor at only a few million years B.P. Yet dating from fossils, whose morphologies are strikingly similar to those of present-day piranhas, strongly suggests that this fish subfamily already existed in South Americas hydrographic system 25 million years ago. The modern species must therefore stem from a recent diversification......... Posted by: Kelly      Read more         Source

December 3, 2007, 10:27 PM CT

Beetle dung helps forests recover from fire

Armed with a pair of tweezers and a handful of beetle droppings, University of Alberta forestry graduate Tyler Cobb has discovered why the bug-sized dung is so important to areas ravaged by fire.

Cobb studied the burned-out area of a northern Alberta hamlet which was partially lost to wildfire during the blazing summer of 2001. By studying a certain species of fire-loving beetles hard at work in the burned and decaying trees, he was able to determine that the insects droppings play a vital role in replenishing soil nutrients that help plants regenerate after a fire.

Cobb, while earning his PhD in the University of Alberta Faculty of Agriculture, Forestry and Home Economics, in the Department of Renewable Resources, worked with about 10 grams of beetle dung50 to 60 beetles can produce just a handfulover two years, slowly teasing it apart with tweezers and chemically analyzing the contents and using it for experiments to pinpoint the benefits to soil.

Beetle droppingsknown in the scientific world as frassare crucial to forests recovering from fire. The tiny piles of droppings, found at the bases of trees, resemble cones of sawdust, and they help nourish the forest floor by increasing microbial activity in the soil. This process can also determine which kinds of trees grow back......... Posted by: Kelly      Read more         Source

December 3, 2007, 10:26 PM CT

Map outlines risk of zebra mussel invasion

The spread of two invasive alien freshwater mussel species the zebra mussel and the quagga mussel appears to be controlled in part by calcium levels in streams and lakes and a new risk assessment based on water chemistry suggests the Great Plains and American Southwest could be next in line for invasion.

Results of the study were published this week in the online version of Frontiers in Ecology and the Environment, a journal of the Ecological Society of America.

The research team that developed the analysis notes that nearly 60 percent of the country, including the Plains states and the Southwest, is in a high-risk ecoregion, based on calcium levels greater than 28 milligrams per liter of water. About 21 percent of the country including New England, most of the Southeast, and the western portions of the Pacific Northwest are at low (12-20 mg) or very low (less than 12 mg) risk for invasion. And in about 19 percent of the country, surface waters have highly variable calcium levels and conditions may change from one lake or river to another, based on geology.

The good news is that many of these high-risk areas dont have a lot of lakes, said Thom Whittier, a faculty research assistant in the Department of Fisheries and Wildlife at Oregon State University and lead author on the study. However, these mussels seem to be working their way west and becoming established in places where theyve never been seen......... Posted by: Kelly      Read more         Source

December 3, 2007, 10:10 PM CT

Choosing dry or wet food for cats

Eventhough society is accustomed to seeing Garfield-sized cats, obese, middle-aged cats can have a variety of problems including diabetes mellitus, which can be fatal. The causes of diabetes mellitus in cats remain unknown eventhough there has been a strong debate about whether a dry food diet puts cats at greater risk for diabetes. A new study from a University of Missouri-Columbia veterinarian suggests that weight gain, not the type of diet, is more important when trying to prevent diabetes in cats.

Because dry cat food contains more starch and more carbohydrates than canned cat food, some have argued that a diet containing large amounts of carbohydrates is unnatural for a cat that is anatomically and physiologically designed to be a carnivore. Carbohydrates constitute between 30 percent and 40 percent of dry cat food. Some have been concerned that this unnatural diet is harmful to cats and leads to increased occurence rate of diabetes. Wet cat food, conversely, is high in protein and more similar to a natural carnivore diet.

In the study, Robert Backus, assistant professor and director of the Nestle Purina Endowed Small Animal Nutrition Program at MU, and his team of scientists compared a colony of cats in California raised on dry food with a colony of cats in New Zealand raised on canned food. After comparing glucose-tolerance tests, which measures blood samples and indicates how fast glucose is being cleared from the blood after eating, scientists found no significant difference between a dry food diet and a wet food diet. They also compared the results between cats less than three years of age and cats older than three. The MU veterinarian indicated that allowing cats to eat enough to become overweight is more detrimental to their health than the type of food they eat......... Posted by: Kelly      Read more         Source

November 15, 2007, 10:10 PM CT

Cutting-edge DNA 'fin-printing' project for salmon

Some salmon make one heck of a commute.

The record holder in the Pacific Northwest, for example, is a steelhead that was tagged in the Clearwater River, Idaho, in April 2003. A year and a half later, it was caught off the southern Kuril Islands near Japan. The most direct route between those two points as the crow flies, as they say is 4,200 miles. Imagine fish that make it that far then turn around and travel back to their home streams in order to spawn.

The ability of salmon to migrate such extraordinary distances makes it hard at a management level to know whose fish are whose and at a biological level to unravel the mystery of their ocean migration.

A $4.1 million effort just launched by the University of Washington's School of Aquatic and Fishery Sciences aims to help by gathering genetic information for thousands upon thousands of Pacific Rim salmon populations and creating open-access databases for managers, treaty-makers and scientists.

Jim and Lisa Seeb, known for their groundbreaking work identifying salmon populations using genetic markers, joined the UW this fall as research professors. Genetic markers are key bits of a fish's DNA that, when in comparison to the same spots on the DNA of other fish, can reveal if they are from the same population or not......... Posted by: Kelly      Read more         Source

November 14, 2007, 9:56 PM CT

Gene in male fish lures females

A gene has been found in male cichlid fish that evolved to lure female fish so that male cichlids can deposit sperm in the females mouths. A study in the online open access journal BMC Biology reveals that the gene is linked to egg-like markings on the fins of cichlid fishes and uncovers the evolutionary history of these markings, which are central to the success of the fishes' exotic oral mating behaviour.

Walter Salzburger, Ingo Braasch and Axel Meyer reared 19 cichlid species at Konstanz University in Gera number of and identified a gene involved in producing yellow pigment cells in oval spots on the fishes' fins. These markings, known as egg-dummies, are found on the anal fins of the male fish and are crucial to mating. The fish are known as maternal mouthbrooders, because once the female has laid her eggs, she picks them up in her mouth. Attracted by what she takes to be eggs - actually the egg-dummy markings - the female then approaches the male. When the female is close to the anal fin, the male discharges sperm into the female's mouth to fertilize the eggs.

Cichlids are a family of fish that include tilapia and angel fish. There are more than 1,800 cichlid species found only in East Africa, and more than 80% of these belong to a grouping known as the haplochromines, which show the characteristic egg dummies......... Posted by: Kelly      Read more         Source

November 14, 2007, 9:33 PM CT

Evolution of strange amphibian breeding habits

Parasites can decimate amphibian populations, but one University of Georgia researcher believes they might also play a role in spurring the evolution of new and sometimes bizarre breeding strategies.

Brian Todd, a researcher at the UGA Odum School of Ecology Savannah River Ecology Lab, explains that most amphibians start their lives in water (tadpoles are a good example), and then make their way onto land as adults and return to the water to breed. But there are other breeding strategies as well. Take, for instance, the Darwin's frog, the species that swallows its eggs and, a few weeks later, regurgitates its young. Or the marsupial frog, a species that carries its eggs on its back until they hatch. Several species lay eggs in small puddles on land or high up in trees where they hatch as miniature versions of adults, bypassing the larval stage entirely.

Researchers have hypothesized that natural selection favored these non-traditional breeding strategies as a way to avoid predatory fish or the risk of a breeding pond or stream drying up. In a review article published in the recent issue of The American Naturalist, Todd argues that the diversity of reproductive strategies that amphibians employ might also be influenced by the benefits that come from avoiding viruses, fungi and other parasites......... Posted by: Kelly      Read more         Source

November 14, 2007, 8:54 PM CT

Differences between humans and chimps

Scientists are closer to understanding why humans differ so greatly from chimpanzees in the way they look, behave, think, and fight off disease, despite having genes that are nearly 99% identical.

Innovative research from the University of Torontos Centre for Cellular and Biomolecular Research has uncovered potential new explanations for these glaring differences. In comparing brain and heart tissue from humans and chimpanzees, U of T Professor Benjamin Blencowe and his team, including graduate student researcher John Calarco, have discovered significant differences in the way genetic material is spliced to create proteins.

Its clear that humans are very different from chimpanzees on several levels, but we wanted to find out if it could be the splicing process that accounts for some of these fundamental differences, says Blencowe, a professor with the Banting and Best Department of Medical Research and Department of Molecular Genetics. The surprising thing we found was that six to eight per cent of the alternative splicing events we looked at were showing differences, which is quite significant. And those genes that showed differences in splicing are linked to a range of important processes, including susceptibility to certain diseases.

Splicing is the process by which the coding regions of genes are joined to generate genetic messages that specify the production of proteins, the key structural and functional constituents of cells. Splicing can occur in alternative ways in the same genetic message to generate more than one type of protein. The new findings reveal that the alternative splicing process differs significantly between humans and chimpanzees......... Posted by: Kelly      Read more         Source