December 16, 2010, 8:02 AM CT

Shellfish That Aren't Safe To Eat

By Susan Brown.

Red tides and similar blooms can render some seafood unsafe to eat, though it can be difficult to tell whether a particular batch harbors toxins that cause food poisoning.

A new kind of marker developed by chemists at the University of California, San Diego, and published in the journal ChemComm makes it easier to see if shellfish are filled with toxin-producing organisms.

Mussels and oysters accumulate single-celled marine creatures called dinoflagellates in their digestive systems as they filter seawater for food. Commonly dinoflagellates are harmless, but sometimes they produce dangerous toxins. The trick is figuring out when.

Researchers think symbiotic bacteria that live on the surface of dinoflagellates probably help synthesize the toxins, but no one is sure how. Genetic tools often used to sort out such relationships don't work for dinoflagellates, which have enormous genomes that are not well understood.

So chemistry professor Michael Burkhart's group took a different approach. They set up a system to add a fluorescent tag to an enzyme that makes one kind of toxin, okadaic acid, but with a twist. By handing the tag to a the molecule that turns the enzyme on, they ensured that only those parts of cells that are capable of making the toxin would glow......... Posted by: Kelly      Read more         Source

December 16, 2010, 7:47 AM CT

Dolphin by-catch includes genetic relatives

Dolphins along coast of Argentina could experience a significant loss of genetic diversity because some of the animals that accidently die when tangled in fishing nets are related. As per a new genetic analysis published this week in the journal PLoS One, Franciscana dolphins that die as by-catch are more than a collection of random individuals: a number of are most likely mother-offspring pairs. This result, which suggests reduced genetic diversity and reproductive potential, could have significant implications for the conservation of small marine mammals.

"It has always been assumed that dolphins could be entangled in fishing nets with family members, but this is one of the very few analyses to demonstrate this result," says Martin Mendez, a postdoctoral researcher at the Sackler Institute for Comparative Genomics at the American Museum of Natural History who led the study. "When family members die as by-catch, a portion of genetic identity of a species is lost, and two important demographic elements of a population are removed: a reproductive female and the next generation".

Franciscana dolphins (Pontoporia blainvillei) have a range that hugs the Atlantic coast of Brazil, Uruguay, and Argentina. This species is one of the world's smallest cetaceans and is a member of the river dolphin family, eventhough it actually lives in coastal waters and estuaries. Females probably begin to have calves between two and five years and probably stay with each calf for some time. Because scientists estimate that between two and five percent of the Fransiscana population near Argentina becomes entangled in fishing nets from small-scale operations each year, the by-catch death rate has a significant impact on the population numbers. By-catch is the biggest impact to small cetacean populations world-wide......... Posted by: Kelly      Read more         Source

December 16, 2010, 7:30 AM CT

Polar bears: On thin ice?

Polar bears were added to the threatened species list nearly three years ago when their icy habitat showed steady, precipitous decline because of a warming climate.

But it appears the Arctic icons aren't necessarily doomed after all, as per results of a study published in this week's issue of the journal Nature

The findings indicate that there is no "tipping point" that would result in unstoppable loss of summer sea ice when greenhouse gas-driven warming rises above a certain threshold.

Researchers from several institutions, including the U.S. Geological Survey (USGS), the National Science Foundation (NSF), and the University of Washington, have observed that if humans reduce greenhouse gas emissions significantly in the next decade or two, enough Arctic ice is likely to remain intact during late summer and early autumn for polar bears to survive.

"What we projected in 2007 was based solely on the business-as-usual greenhouse gas scenario," said Steven Amstrup, an emeritus researcher at the USGS and senior scientist at the Montana-based organization Polar Bears International. "That was a pretty dire outlook, but it didn't consider the possibility of greenhouse gas mitigation".

Amstrup is the main author of this week's Nature paper. Co-authors are Eric DeWeaver of NSF, David Douglas and George Durner of the USGS Alaska Science Center, Bruce Marcot of the U.S. Forest Service in Oregon, Cecilia Bitz of the University of Washington, and David Bailey of the National Center for Atmospheric Research in Boulder, Colo......... Posted by: Kelly      Read more         Source

December 15, 2010, 7:09 AM CT

Light in bizarre bioluminescent snail

Two researchers at Scripps Institution of Oceanography at UC San Diego have provided the first details about the mysterious flashes of dazzling bioluminescent light produced by a little-known sea snail.

Dimitri Deheyn and Nerida Wilson of Scripps Oceanography (Wilson is now at the Australian Museum in Sydney) studied a species of "clusterwink snail," a small marine snail typically found in tight clusters or groups at rocky shorelines. These snails were known to produce light, but the scientists discovered that rather than emitting a focused beam of light, the animal uses its shell to scatter and spread bright green bioluminescent light in all directions.

The researchers, who describe their findings in the Dec. 15 online version of Proceedings of the Royal Society B (Biological Sciences), say the luminous displays of Hinea brasiliana could be a deterrent to ward off potential predators by using diffused bioluminescent light to create an illusion of a larger animal.

In experiments conducted inside Scripps' Experimental Aquarium facility, Deheyn documented how H. brasiliana set off its glow, which he likens to a burglar alarm going off, when the snail was confronted by a threatening crab or a nearby swimming shrimp.

Wilson collected the snails used in the study in Australia and collaborated with Deheyn to characterize the bioluminescence......... Posted by: Kelly      Read more         Source

December 13, 2010, 7:00 AM CT

How vultures colonize the Canary Islands

The Egyptian vulture population of the Canary Islands was established following the arrival of the first human settlers who brought livestock to the islands. A genetic comparison of Iberian and Canarian birds, reported in the open access journal BMC Evolutionary Biology, observed that the Egyptian vulture population in the Canary Islands was likely established around 2500 years ago around the same time as humans began to colonise the islands.

Rosa Agudo worked with a team of scientists from the Doana Biological Station, Seville, Spain, to investigate genetic and morphological changes between 143 Iberian birds and 242 from Fuerteventura, one of the Canary Islands. She said, "We observed that the island vultures are significantly heavier and larger than those from Iberia. The establishment of this insular population took place some 2500 years ago, matching the date of human colonization. Our results suggest that human activity can trigger divergent evolution and that this process may take place on a relatively brief time scale".

The authors suggest that before the arrival of humans, the Canary Islands would not have been able to support vultures, as food resources would have been scarce, consisting only of the remains of seabirds and sea mammals, or of rodents. They say, "The introduction of new and abundant food sources by humans could have allowed not only colonization by vultures, but also their demographic expansion and their putative adaptation to the new island environment". For once, human activity has actually assisted in the diversification and adaptation of the Egyptian vulture, now globally threatened and classified as 'Endangered' on the IUCN Red List......... Posted by: Kelly      Read more         Source

December 9, 2010, 7:55 AM CT

mouse from 2 fathers

Using stem cell technology, reproductive researchers in Texas, led by Dr. Richard R. Berhringer at the M.D. Anderson Cancer Center, have produced male and female mice from two fathers.

The study was posted today (Wednesday, December 8) at the online site of the journal Biology of Reproduction

The achievement of two-father offspring in a species of mammal could be a step toward preserving endangered species, improving livestock breeds, and advancing human assisted reproductive technology (ART). It also opens the provocative possibility of same-sex couples having their own genetic children, the scientists note.

In the work reported today, the Behringer team manipulated fibroblasts from a male (XY) mouse fetus to produce an induced pluripotent stem (iPS) cell line. About one percent of iPS cell colonies grown from this XY cell line spontaneously lost the Y chromosome, resulting in XO cells. The XO iPS cells were injected into blastocysts from donor female mice. The treated blastocysts were transplanted into surrogate mothers, which gave birth to female XO/XX chimeras having one X chromosome from the original male mouse fibroblast.

The female chimeras, carrying oocytes derived from the XO cells, were mated with normal male mice. Some of the offspring were male and female mice that had genetic contributions from two fathers......... Posted by: Kelly      Read more         Source

December 8, 2010, 7:19 AM CT

Bird call database nests online

A growing online library of bird sounds, photos and information offers a new resource for backyard birders and seasoned ornithologists alike.

The Avian Vocalizations Center at Michigan State University, or AVoCet,offers free downloads of bird sounds from around the world. It also features sonograms that visually chart the sounds, photos of birds recorded, Google Earth maps of recording locations and links to other online sound collections.

More than 10,200 recordings from over 3,190 species in 45 countries are now available on AVoCet, "and that's growing quickly," said Pamela Rasmussen, an assistant professor of zoology and assistant curator at the MSU Museum. "Soon recordings and their data from a number of more species and areas will be available for download from AVoCet".

There are, after all, 10,000 bird species, all of which make sounds of some type. A number of birds, such as cardinals, even sing in regional dialects. Some birds have huge vocabularies a single male Brown Thrasher is known to give 2,000 different notes.

Author of an exhaustive reference work on the birds of South Asia, Rasmussen haccording tosonally recorded on all the continents for this project. Her work in the Philippines alone netted 597 recordings of 120 species, a number of of which are threatened. Some of those sound types are not publicly available anywhere other than AVoCet......... Posted by: Kelly      Read more         Source

December 7, 2010, 7:40 AM CT

Life Histories of Dead Whales

Dead whales that sink down to the seafloor provide a feast for deep-sea animals that can last for years. Prior research suggested that such "whale falls" were homes for unique animals that lived nowhere else. However, after sinking five whale carcasses in Monterey Canyon, scientists from the Monterey Bay Aquarium Research Institute (MBARI) observed that most of the animals at these sites were not unique to whale falls, but were common in other deep-sea environments as well. Nonetheless, the whale-fall communities did include a few very abundant animals that were "bone specialists," including 15 species of bone-eating Osedax worms and several newly discovered species of bone-eating snails.

In 2004, evolutionary biologist Robert Vrijenhoek and colleagues announced the discovery of a new family of bone-eating worms, which they found two years earlier living on a dead whale in Monterey Canyon, almost 3,000 meters below the sea surface.

Following this discovery, Vrijenhoek's team set out to study how these worms survived, reproduced, and spread from one whale carcass to another. To this end, MBARI scientists and marine operations staff hauled five very smelly dead whales off the beaches of Monterey Bay, attached weights to the carcasses, and sank them at different depths in Monterey Canyon......... Posted by: Kelly      Read more         Source

December 7, 2010, 7:37 AM CT

Key to Improving World Grape Production

In a few years, a sip of Cabernet Sauvignon, Merlot or Pinot Noir may include a taste of the "Show-Me" State. The state grape of Missouri - the Norton variety grown at a number of vineyards around the state - is resistant to powdery mildew, a fungal pathogen that affects winemaking grapes around the world. Now, scientists at the University of Missouri are working to identify valuable genes from the Norton grape for eventual transfer into other grapes to make them less susceptible to mildew, decrease fungicide use and increase world-wide grape production.

"The hot, humid environment of Missouri is perfect for the growth of fungal pathogens, such as mildew, yet Norton resists the fungus," said Walter Gassmann, a researcher in the Bond Life Sciences Center and associate professor of plant sciences in the College of Agriculture, Food and Natural Resources. "Understanding what makes Norton resistant to fungus, and European varieties, such as Cabernet Sauvignon, susceptible to fungus, can help us improve grape production around the world."

Scientists say the difference between the Norton grape and other varieties is that the Norton grape builds more of a certain protein that is essential to fight fungal pathogens than other grape varieties, which build too little of the protein too late to successfully battle the fungus. Earlier research has discovered the gene that contains the blueprint for this protein present in both Norton grapes and other varieties that cannot resist the mildew. Gassmann is conducting research on the fast-growing Arabidopsis plant, which features a gene similar to the targeted grape gene. His team added the grapevine gene to an Arabidopsis plant that was lacking its own gene. Adding the grapevine gene led to plants that resisted the mildew, confirming that the grapevine gene is responsible for orchestrating plant defenses against mildew. The next step in this research is to figure out what in the genetic instructions is different in Norton and other grapevine varieties that leads to the observed difference in protein levels in resistant Norton and susceptible grapevines......... Posted by: Erica      Read more         Source

November 23, 2010, 7:58 AM CT

The Puzzle of Biological Diversity

Biologists have long thought that interactions between plants and pollinating insects hasten evolutionary changes and promote biological diversity. However, new findings show that some interactions between plants and pollinators are less likely to increase diversity than previously thought, and in some instances, reduce it.

Findings, reported in the Journal of Evolutionary Biology, show that local populations of one of the most distinctive plants in the Mojave Desert, the Joshua tree, are not as biologically diverse as would be expected. Joshua trees cannot produce seeds without specialized moths pollinating the tree's flowers. Prior research has shown that biological diversity exists among species of Joshua trees and their pollinating moths: Moths with longer ovipositors, the part of the moth used to lay eggs, favor trees with large flowers, while smaller moth species favor smaller flowers. Thus, biologists would expect the moths would adapt this trait to local flower populations and vice versa in order to reproduce. Yet using a combination of mathematical modeling and field studies, scientists observed little biological diversity among populations and thus no evidence that local populations of moths adapt to local populations of Joshua trees.

"We had previously observed two species of moths and have shown that the larger moth species uses large flowers and the smaller moth species uses smaller flowers. However, once we account for this difference, there no evidence that moths have adapted to flowers," said William Godsoe, the study's main author and postdoctoral researcher at the National Institute for Mathematical and Biological Synthesis......... Posted by: Kelly      Read more         Source