May 10, 2007, 10:27 PM CT

Personality-Gene makes Songbirds Curious

There is already evidence that variations (polymorphisms) in neurotransmitter-related genes are linked to personality differences among humans. Research from the last decade suggested a promising link between the Drd4-gene and the trait curiosity (novelty-seeking). Researchers from the Max Planck Institute for Ornithology in Seewiesen, together with a former lab member who is now at the Cawthron Institute in Nelson (New Zealand) and with colleagues from the Netherlands Institute of Ecology in Heteren, have shown that the choice of the Drd4-gene in the study of the great tit turned out to be a good bet.

In the Drd4 gene of this bird, they discovered 73 polymorphisms, of which 66 were so-called Single Nucleotide Polymorphisms (SNPs), where only a single nucleotide has been exchanged between the two variants. One such SNP, located at position 830, is indeed linked to the exploratory behaviour (read: curiosity) of the birds. This is first shown in two breeding lines of great tits, which the scientists had selected over four generations as per their level of curiosity (a low and a high curiosity line). The researchers assessed the curiosity of the birds in a test which shows similarities to the traditional "open-field" test used by psychology experts. They tested the exploratory behaviour of each bird soon after it left the nest (Early Exploratory Behaviour, EEB), as follows. In one behavioural test, the biologists measured the time until a bird had visited four artificial "trees" (see figure 1) after being released in the observation room. In a second test, they quantified the reaction of the bird towards each of two unknown objects that had been put in its cage. One such novel object was a pink panther......... Posted by: Kelly      Read more         Source

May 9, 2007, 11:18 PM CT

DNA reveals hooded seals have wanderlust

Scientists have discovered a new fact about hooded seals, a mysterious 200 to 400 kilogram mammal that spends all but a few days each year in the ocean.

An international team of scientists led by Dr. David Coltman, an evolutionary geneticist at the University of Alberta, have learned that all the hooded seal populations in the world share the same genetic diversity. The scientists reached their conclusions after analysis of more than 20 years of DNA samples taken from hundreds of hooded seals from around the world.

"These results mean that if you brought me a DNA sample of a hooded seal, I wouldn't be able to tell you where in the world you got that sample because of the genetic similarity between populations," Coltman said.

"This is important information because it helps shed light on an animal that we know very little about," he added.

Female hooded seals give birth (whelp) and wean their pups on ice floes over a period of three to four days once every year in the spring. Male seals wait until the females finish weaning for the one time of year when they will mate. The scientists believe the genetic similarities among the seals indicate these seals intermingle and mate among populations.

The research is published this month in the journal Molecular Ecology......... Posted by: Kelly      Read more         Source

May 9, 2007, 11:14 PM CT

Plants tag insect herbivores with an alarm

Rooted in place, plants can't run from herbivoresbut they can fight back. Sensing attack, plants frequently generate toxins, emit volatile chemicals to attract the pest's natural enemies, or launch other defensive tactics.

Now, for the first time, researchers reporting in the June 2007 issue of Plant Physiology have identified a specific class of small peptide elicitors, or plant defense signals, that help plants react to insect attack.

In this colorful self-defense strategy, proteins already present in the plant are ingested by insect attackers. Digesting the proteins, the insects unwittingly convert this food into a peptide elicitor, which gets secreted back onto plants during later feedings. Recognizing the secreted elicitor as a kind of "SOS," plants launch defensive chemistry. This defense discovery opens the door for the development and genetic manipulation of plants with improved protection against pests.

Although researchers have long known that some plants distinguish different insect attackers, this defensive behavior has proven difficult to describe at the molecular level. Exceedingly few model systems have been utilized to characterize the potential interactions between what researchers estimate to be at least four million insects and 230,000 flowering plant species. Moreover, highly active plant defense signals can occur at trace levels, too small to easily detect or isolate......... Posted by: Erica      Read more         Source

May 9, 2007, 10:29 PM CT

First Marsupial Genome Sequence

An international team, led by scientists at the Broad Institute of MIT and Harvard, and supported by the National Institutes of Health (NIH), today announced the publication of the first genome of a marsupial, belonging to a South American species of opossum. In a comparison of the marsupial genome to genomes of non-marsupials, including human, reported in the May 10 issue of the journal Nature, the team observed that most innovations leading to the human genome sequence lie not in protein-coding genes, but in areas that until recently were referred to as "junk" DNA.

The effort to generate the high-quality genome sequence of the gray short-tailed, South American opossum, Monodelphis domestica, began in 2003 and cost approximately $25 million. The sequencing work was funded by the National Human Genome Research Institute (NHGRI), part of the NIH, and carried out at the Broad Institute Sequencing Platform, which is a member of NHGRI's Large-Scale Sequencing Research Network.

"The opossum genome occupies a unique position on the tree of life. This analysis fills a crucial gap in our understanding of how mammalian genomes, including our own, have evolved over millions of years," said NHGRI Director Francis S. Collins, M.D., Ph.D. "These new findings illustrate how important it is to understand all of the human genome, not just the fraction that contains genes that code for proteins. We must identify all functional elements in the genome if we are to have the most complete toolbox possible to explore human biology and improve human health"......... Posted by: Janet      Read more         Source

May 7, 2007, 11:08 PM CT

Is climate change likely to increase disease in corals?

Coral reefs, among Earth's richest ecosystems, traditionally teem with an abundance of life. But in recent years, corals have been dying in droves. Researchers suspect a variety of factors, ranging from accidental damage from fishing activity to the effects of polluted runoff from land. One threat that appears to be growing dramatically in Australia's famed Great Barrier Reef is white syndrome, a disease that is spreading rapidly, leaving stripes of dead corals like ribbons of death in its wake. In a new study published by PLoS Biology, John Bruno, Amy Melendy, and his colleagues show that the interaction between anomalously high ocean temperatures and the extent of coral cover is likely to account for the occurrence of the disease.

Global warming has seemed a likely suspect for several reasons. Past epidemiological studiesacross a broad range of life formshave shown that stress, including the stress of changing environmental conditions, often increases disease susceptibility. As temperatures rise, pathogens can reproduce more quickly. The fact that coral diseases seem to spread faster in summer also provides support for the notion that warmer temperatures may be involved. The authors conducted a regional-scale longitudinal study of the hypothesized link between warm temperature deviations and the presence of white syndrome, considering the density of coral cover as an additional variable of interest. To quantify temperature fluctuations, the scientists used a high resolution dataset on ocean surface temperature provided by the United States National Oceanic and Atmospheric Association and the University of Miami. They used the dataset to calculate w eekly sea surface temperature anomalies (WSSTAs), instances in which temperature was higher by 1C or more from mean records for that week, for 48 reefs within the Great Barrier Reef. To evaluate the extent of white syndrome and coral cover, the scientists used data collected by the Australian Institute of Marine Science Long-term Monitoring Program on 48 reefs from a 1,500-kilometer stretch of the Great Barrier Reef from 1998 to 2004 at a depth of six to nine meters. Divers counted the number of infected colonies on each reef. Coral cover, the amount of the bottom with living corals, was measured from videos taken of the reefs......... Posted by: Janet      Read more         Source

May 7, 2007, 10:54 PM CT

Tropical plants go with the flow of nitrogen

Tropical plants are able to adapt to environmental change by extracting nitrogen from a variety of sources, as per a new study that appears in the May 7 early online edition of The Proceedings of the National Academy of Sciences.

By demonstrating that not all plants specialize in one specific source of nitrogen, the result turns a usually held theory on its head. It also provides a dose of optimism that tropical forests will be able to withstand environmental shifts in nutritional cycles brought on by global climate change.

Nitrogen is an essential nutrient that plants must absorb from the soil to survive. Most land plants outside the tropics appear to have evolved to rely on just one of three common sources of nitrogen: nitrate (NO3-), ammonium (NH4+), or dissolved organic nitrogen (DON). As a result of this limitation, they commonly inhabit "niches" defined largely by the available nitrogen source. When that source crashes for any reasonoften because of shifts in climatethe plants cannot adapt, with potentially disastrous consequences for natural ecosystems.

However, tropical species appear to be far more adaptable than their temperate kin when it comes to their nitrogen needs. A team of researchers* has observed that, when confronted with shifts in nitrogen availability, these plants simply "flip a switch" and use whatever is handy......... Posted by: Erica      Read more         Source

May 6, 2007, 4:59 PM CT

Gene mutation linked to increased athletic performance

Whippets are bred for speed and have been clocked at speeds approaching 40 miles per hour over a 200-yard racing course. Researchers at the National Human Genome Research Institute (NHGRI), part of the National Institutes of Health (NIH), have now discovered a genetic mutation that helps to explain why some whippets run even faster than others. Reported in the open-access journal PLoS Genetics, their findings will make for a fascinating experiment in applied genetics and human nature: what will dog breeders do with this information, and what are the implications for human athletic performance?

A research team led by Elaine Ostrander, chief of the Cancer Genetics Branch in NHGRIs Division of Intramural Research, reports that a mutation in a gene that codes for a muscle protein known as myostatin can increase muscle mass and enhance racing performance in whippets. Like humans, dogs have two copies of every gene, one inherited from their mother and the other from their father. Dr. Ostrander and his colleagues found those whippets with one mutated copy of the myostatin (MTSN) gene and one normal copy to be more muscled than normal and are among the breeds fastest racers. However, their research also showed that whippets with two mutated copies of the MTSN gene have a gross excess of muscle and are rarely found among competitive racers......... Posted by: Kelly      Read more         Source

May 6, 2007, 4:43 PM CT

Light sticks may lure turtles to fishing lines

Thousands of loggerhead turtles die every year when they get tangled or hooked in commercial fishing longlines meant for tuna or swordfish. New research suggests a possible reason why turtles swim into the lines. The glowing light sticks that lure fish to longlines also attract turtles, as per a University of North Carolina at Chapel Hill study.

The light sticks used in longline fisheries resemble the disposable plastic tubes popular with children on Halloween. The steady glow draws fish, which then find baited hooks and are caught on the lines. The lights also seem to fascinate turtles, however, which are equally likely to chomp on fish bait, or get snagged in the hooks and lines.

"Juvenile turtles are indiscriminant eaters and bite nearly everything small that they encounter," said Ken Lohmann, UNC-Chapel Hill professor of biology and senior author of the study. "Under natural conditions, most small objects floating or swimming through the sea are potential sources of food. But nowadays, with fishing lines, plastic, and garbage in the ocean, biting everything is not such a great strategy".

The study appears in the May 2007 issue of the journal Animal Conservation. John Wang, a former graduate student at Carolina and now a research associate with the Joint Institute for Marine and Atmospheric Research at the University of Hawaii, was the lead author of the study. Grants from the National Oceanic & Atmospheric Administration (NOAA) and the National Science Foundation provided funding......... Posted by: Kelly      Read more         Source

April 30, 2007, 8:08 PM CT

First Genome Comparison of Plankton Species

An international team of researchers led by Scripps Institution of Oceanography at UC San Diego and the Department of Energy's (DOE) Joint Genome Institute has peered into the genetic makeup of two species of phytoplankton, the tiny plants key in global photosynthesis and carbon cycling, and come away with surprising results about evolutionary engineering and new ideas about the role that a poorly understood chemical element may play in the world's oceans.

For several years, Scripps Oceanography's Brian Palenik and his collaborators, including researchers from France, Belgium and Gera number of, have been analyzing and annotating an organism called Ostreococcus. At one micron it is the smallest known phytoplankton and one of the smallest of all the eukaryotes, organisms with specialized internal cell structures that include plants and animals. A teaspoon of seawater taken off the Scripps Oceanography Pier typically contains more than 100,000 eukaryotic phytoplankton, which are found throughout the world's oceans. Phytoplankton are responsible for nearly half of the planet's photosynthesis.

Advances in genomics have allowed researchers to begin digging deeply into a long-standing biological puzzle concerning the mechanisms behind the divergent genomes of related photosynthetic phytoplankton species. The international team's work, reported in the online edition of Proceedings of the National Academy of Sciences, is the first comparison of the genetic makeup of two closely related eukaryotic phytoplankton and the mechanisms that make them biologically similar and distinct......... Posted by: Janet      Read more         Source

April 30, 2007, 7:02 PM CT

Seeing the trees for the forest

After completing a two-year pilot phase, researchers at the Woods Hole Research Center are expanding the scope of the "National Biomass and Carbon Dataset" for the year 2000 (NBCD2000), the first ever inventory of its kind, by moving into the production phase. Through a combination of NASA satellite datasets, topographic survey data, land use/land cover data, and extensive forest inventory data collected by the U.S. Forest Service Forest Inventory and Analysis Program (FIA), NBCD2000 will be an invaluable baseline data set for the assessment of the carbon stock in U.S. forest vegetation and will improve current methods of determining carbon flux between vegetation and the atmosphere. Work on the remaining 61 mapping zones will be completed at a rate of roughly one zone every seven working days.

As per Josef Kellndorfer, an associate scientist at the Center who is leading the project, "Understanding this flux is critical for the quantification and prediction of atmospheric CO2 concentrations, a major determinant of the greenhouse warming effect in the climate system. Thus, this initiative will directly support the North American Carbon Program, which is a major component of the U.S. Climate Change Research Program".

In the NBCD2000 initiative, begun in 2005, data is being analyzed in 66 ecologically diverse regions, termed "mapping zones", which span the conterminous United States. Within each mapping zone data from the 2000 Shuttle Radar Topography Mission are combined with topographic survey data from the National Elevation Dataset (NED) to produce a radar-based height map of vegetation. Subsequently, this map is converted to estimates of actual vegetation height, biomass, and carbon stock using survey data from the U.S. Forest Service FIA program and ancillary data sets from the National Land Cover Database 2001 (NLCD2001) project. The NLCD2001 data layers are crucial inputs to the NBCD2000 project as they provide land cover and canopy density information used in the stratification/calibration process......... Posted by: Erica      Read more         Source