September 24, 2007, 10:06 PM CT

Dams and California salmon

Spring-run Chinook salmon and other fish in the rivers of Californias Central Valley could be harmed by more water-storage dams, as per scientists at Duke University and the National Oceanic and Atmospheric Administration.

The findings of a recent paper may serve as a cautionary tale to policymakers, researchers and resource managers currently embroiled in a debate about the construction of new dams in the region.

The paper, Directed Connectivity Among Fish Populations in a Riverine Network, was reported in the September 3 online issue of Journal of Applied Ecology.

Robert S. Schick, of the University Program in Ecology at Duke's Nicholas School of the Environment and Earth Sciences, used analytical techniques from network science to study the relative importance of individual populations of salmon within the valley and examined how the addition of large water-storage dams blocked access to habitat and fragmented these populations over time.

"We observed that fragmented populations became increasingly vulnerable to disturbance and extinction," said Schick, who co-wrote the paper with Steven T. Lindley of NOAAs Southwest Fisheries Science Center in Santa Cruz, Calif.

The paper has become topical thanks to a recent $9 billion bond proposal by California Gov. Arnold Schwarzenegger to construct two new dams and expand a third in the environmentally fragile Sacramento-San Joaquin River Delta......... Posted by: Kelly      Read more         Source

September 24, 2007, 9:56 PM CT

Sunburn for us protecton for crayfish

The production of melanin gives us sunburns, but it also helps invertebrate animals to encapsulate attacking fungi and parasites. Uppsala University researchers, in collaboration with Korean and Thai colleagues, can now show that melanin also protects against bacterial infections, at least in crayfish. The study is reported in the latest Net edition of Journal of Biological Chemistry.

The production of melanin is an important protective reaction that gives us a sunburn, for instance. In invertebrate animals it has long been found that parasites, fungi, and other invaders become encapsulated in melanin. In a number of animals this can be seen as black-brown spots on the shell that show that the animal has had an infection.

"In mosquitoes that can harbor the malaria parasite it has also been found that the mosquitos ability to form such melanin capsules often determines whether it will be able to spread the disease to humans," says Haipeng Liu.

Conversely, the possible effect of melanin production on bacterial infections has been intensively debated. In the current study the researchers show, by manipulating the genetic expression of the melanin-producing enzyme, that effective melanin production is crucial to the ability of freshwater crayfish to survive an infection of an extremely dangerous bacteria for them, Aeromonas hydrophila......... Posted by: Kelly      Read more         Source

September 24, 2007, 9:46 PM CT

Rare albino ratfish has eerie, silvery sheen

A ghostly, mutant ratfish caught off Whidbey Island in Washington state is the only completely albino fish ever seen by both the curator of the University of Washington's 7.2 million-specimen fish collection and a fish and wildlife biologist with more than 20 years of sampling fish in Puget Sound.

"Ratfish commonly hang out in places with soft, muddy bottoms," says Jon Reum, the aquatic and fishery sciences doctoral student who found the albino ratfish during a UW research project. "The typical ratfish in Puget Sound is brown or black with a smattering of white spots so it blends in with the sediments".

This fish was almost pure white with a crystalline layer near the surface of its skin that gave it a silvery sheen.

"It must have been like a beacon," says Ted Pietsch, UW professor of fisheries and aquatic sciences and curator of the UW fish collection. "Why didn't it get eaten, long before this, by some predator, for example, by a spiny dogfish so common in Puget Sound and that love to devour ratfish"".

The foot-long female may have been 2 or 3 years old, Reum and Pietsch estimate, making her a teenager in the ratfish world.

She was caught this summer in about 200 feet of water during a UW research project examining the food web in Hood Canal and Puget Sound. Puget Sound is the nation's second-largest estuary in the Lower 48 after Chesapeake Bay. The city of Seattle, home to about 4 million people, is built on its shores. Puget Sound connects to the Pacific Ocean via the Strait of Juan de Fuca to the north......... Posted by: Kelly      Read more         Source

September 23, 2007, 11:21 AM CT

Amazon forest shows unexpected resiliency

Drought-stricken regions of the Amazon forest grew especially vigorously during the 2005 drought, as per new research.

The counterintuitive finding contradicts a prominent global climate model that predicts the Amazon forest would begin to "brown down" after just a month of drought and eventually collapse as the drought progressed.

Instead of hunkering down during a drought as you might expect, the forest responded positively to drought, at least in the short term," said study author Scott R. Saleska of The University of Arizona. "It's a very interesting and surprising response."

UA co-author Kamel Didan added, "The forest showed signs of being more productive. That's the big news".

The 2005 drought reached its peak at the start of the Amazon's annual dry season, from July through September. Eventhough the double whammy of the parched conditions might be expected to slow growth of the forest's leafy canopy, for a number of of the areas hit by drought, the canopy of the undisturbed forest became significantly greener -- indicating increased photosynthetic activity.

Saleska, a UA assistant professor of ecology and evolutionary biology, and colleagues at the UA and at the University of So Paulo in Brazil used data from two NASA satellites to figure out that undisturbed Amazon forest flourished as rainfall levels plummeted......... Posted by: Erica      Read more         Source

September 21, 2007, 6:39 AM CT

New Strategy To Create Genetically Modified Animals

Scientists at the University of Pennsylvania School of Veterinary Medicine have demonstrated the potential of a new strategy for genetic modification of large animals. The method employs a harmless gene treatment virus that transfers a genetic modification to male reproductive cells, which is then passed naturally on to offspring.

Ina Dobrinski, associate professor and director of the Center for Animal Transgenesis and Germ Cell Research at Penn Vet, and her colleagues introduced adeno-associated virus, AAV, to male germline stem cells in both goats and mice. The study showed that AAV stably transduced male germ line stem cells and led to transgene transmission through the male germ line.

The findings, available online in The FASEB Journal and in the February 2008 print edition, are the first report of transgenesis via germ cell transplantation in a non-rodent species, a promising approach to germ line genetic modification. It also demonstrates that germline transduction and germ cell transplantation in large animals provides an approach that is potentially less costly than microinjection and cloning, the traditional methods used to generate transgenic large animal models for biomedical research.

Scientists used mouse germ cells harvested from experimentally induced cryptorchid donor testes that were then exposed in vitro to AAV vectors carrying a green fluorescent protein transgene and transplanted to germ cell-depleted recipient testes, resulting in colonization of the recipient testes by transgenic donor cells......... Posted by: Kelly      Read more         Source

September 21, 2007, 5:30 AM CT

Key to longer life (in flies) lies in just 14 brain cells

Two years ago, Brown University scientists discovered something startling: Decrease the activity of the cancer-suppressing protein p53 and you can make fruit flies live significantly longer.

Now the same team reports an intriguing follow-up finding. The p53 protein, they found, may work its lifespan-extending magic in only 14 insulin-producing cells in the fly brain.

Its quite surprising, said Johannes Bauer, a postdoctoral research fellow at Brown. In the fruit fly brain, there are tens of thousands of cells. But we observed that it takes a reduction of p53 activity in only 14 of those brain cells to extend lifespan. It was like finding a needle in the haystack a very small needle at that.

Bauer is the lead author of the research report, reported in the Proceedings of the National Academy of Sciences. Brown biology professor Stephen Helfand, senior scientist on the project, will discuss the findings in his keynote address at the Gordon Research Conferences on the Biology of Aging, to be held Sept. 23-28, 2007, in Les Diablerets, Switzerland.

P53 is sometimes called guardian of the genome for defending cells against DNA damage. Not enough of the protein can cause cancer; too much, however, can shorten lifespan. But in 2005, Helfand and his lab showed that a targeted decrease of p53 in fruit flies a decrease specifically in their brain cells allowed flies to live healthy lives that were as much as 58 percent longer......... Posted by: Kelly      Read more         Source

September 18, 2007, 10:10 PM CT

Bats add their voice to the FOXP2 story

When it comes to the FOXP2 gene, humans have had most to shout about. Discoveries that mutations in this gene lead to speech defects and that the gene underwent changes around the time language evolved both implicate FOXP2 in the evolution of human language. More recently, patterns of gene expression in birds, humans and rodents have suggested a wider role in the production of vocalisations. Yet numerous reports have established that FOXP2 shows very little genetic variation across even distantly related vertebrates - from reptiles to mammals providing few extra clues as to the genes role.

A new study, undertaken by a joint of team of British and Chinese scientists, has observed that this gene shows unparalleled variation in echolocating bats. The results, appearing as per a research findings reported in the online, open-access journal PLoS ONE on September 19, report that FOXP2 sequence differences among bat lineages correspond well to contrasting forms of echolocation.

Like speech, bat echolocation involves producing complex vocal signals via sophisticated coordination of the mouth and face. The involvement of FOXP2 in the evolution of echolocation adds weighty support to the theory that FOXP2 functions in the sensory-motor coordination of vocalisations......... Posted by: Kelly      Read more         Source

September 18, 2007, 10:08 PM CT

More Viable Offspring If They Can Choose Their Best Mate

When it comes to picking a mate, Crosby, Stills, Nash and Young had an answer: If you cant be with the one you love, love the one youre with. As it turns out, that may be a cardinal rule in the animal kingdom, too.

New research that crosses several species boundaries shows that when animals must choose less-than-preferred (to them) mates, females and males apparently have ways to compensate that increase the chance their offspring will survive. The study, just reported in the Proceedings of the National Academy of Sciences, adds weight to the Compensation Hypothesis, a proposal that has given insight into how individuals can pass on their genes even under less than ideal circumstances.

Its always better for offspring if parents can mate with preferred partners, but its becoming clear that when parents cant have that preferred partner, they have ways of making up for it, said Patricia Adair Gowaty, a Distinguished Research Professor of Ecology and Genetics at the University of Georgia and lead author of the study. When female choosers were in enforced pairs with males they did not prefer, they laid more eggs. Similarly, when males are paired with females they do not prefer, they ejaculate more sperm. This compensation seems to be a way of making the best of a bad job......... Posted by: Kelly      Read more         Source

September 18, 2007, 8:03 PM CT

Solving the snail biogeography puzzle

The answer to a mystery that long has puzzled biologists may lie in prehistoric Polynesians' penchant for pretty white shells, a research team headed by University of Michigan mollusk expert Diarmaid Ó Foighil has found.

The team's findings, published online Sept. 12 in the British biological research journal Proceedings of the Royal Society B, have implications for conservation efforts aimed at rescuing nearly-extinct Tahitian tree snails.

The study focused on a tree snail species, Partula hyalina, found on the island of Tahiti-where it has been nearly wiped out by a predatory snail introduced in the 1970s-and also on the Austral and Southern Cook Islands. The snail's multiarchipelago distribution is unique in the partulid tree snail family; most are restricted to single islands.

But even more intriguing is the observation that while this snail exhibits a range of shell colors on Tahiti, including white, only white-shelled variants are found in the Austral and Southern Cook Islands. What's more, P. hyalina-white-shelled or otherwise-isn't found at all on Tahiti's nearest neighbors, Moorea and the other islands in the Society archipelago.

The odd distribution pattern has had biologists scratching their heads since at least the 1880s. Over the years they've come up with a variety of possible explanations, suggesting for example that the white-shelled forms are actually all distinct species that independently evolved on different islands......... Posted by: Kelly      Read more         Source

September 17, 2007, 5:19 AM CT

Yam bean a nearly forgotten crop

The Yam bean originated where the Andes meet the Amazon and is locally grown in South and Central America, South Asia, East Asia and the Pacific. It is produced in three species which are called the Amazonian, Mexican and Andean. Interbreeding of the bean has resulted in fertile and stable hybrids. This gives it potential to be reclassified as a single species, provide high quality food production and offer a sustainable cropping system that has been needed in Africa.

Scientists believe they have discovered a protein-rich starch staple in the yam bean in Peru. They were previously considered a root vegetable due to the high water content; however this Chuin type has lower water content. Families living in the area have been producing it as flour. The crop has extremely high seed production, but its seeds contain high concentrations of rotenone. This toxic compound has been used for reducing fish populations and parasitic mites on poultry. Seeds are never consumed since they are mildly toxic to humans and other mammals. If the rotenone was removed from the seeds, they could provide a strong protein source as well as seed oil profitable in the food industry.

Sraphin Zanklan, a scientist at Centre Songhai in Porto-Novo (Benin), has investigated the yam bean for its potential to grow and produce food under West African conditions. The study was funded by a scholarship from the German Academic Exchange Service (DAAD). Thirty-four yam genotypes were grown with and without flower removal at one droughty location and one irrigated location. Of the 33 traits that were measured, nearly all showed large genetic variation. This and the easy spreading of its seeds, make the crops very desirable to breeders. Results from the study would be reported in the July-August 2007 issue of Crop Science......... Posted by: Erica      Read more         Source