December 10, 2009, 10:33 PM CT

Killer catfish?

Name all the venomous animals you can think of and you probably come up with snakes, spiders, bees, wasps and perhaps poisonous frogs. But catfish?

A newly released study by University of Michigan graduate student Jeremy Wright finds that at least 1,250 and possibly more than 1,600 species of catfish appears to be venomous-far more than previously believed. The research is described in a paper published online Dec. 4 in the open access journal BMC Evolutionary Biology.

Lest anyone have concerns about attacks of killer catfish, rest assured that, at least in North America, these finned fatales use their venom mainly to defend themselves against predatory fish, though they can inflict a painful sting that a number of fishermen have suffered. In other parts of the world, some catfish do have extremely toxic venoms that can be deadly to humans.

Researchers have focused a great deal of attention of venom produced by snakes and spiders, but venomous fish had been largely neglected, said Wright, who used histological and toxicological techniques, as well as prior studies of evolutionary relationships among catfish species, to catalog the presence of venom glands and investigate their biological effects.

Catfish venom glands are found alongside sharp, bony spines on the edges of the dorsal and pectoral fins, and these spines can be locked into place when the catfish is threatened. When a spine jabs a potential predator, the membrane surrounding the venom gland cells is torn, releasing venom into the wound. In his paper, Wright describes how catfish venoms poison nerves and break down red blood cells, producing such effects as severe pain, reduced blood flow, muscle spasms and respiratory distress. However, because none of the species he examined produces more than three distinct toxins in its venom, each species probably displays only a subset of the whole repertoire of effects......... Posted by: Kelly      Read more         Source

December 10, 2009, 7:54 AM CT

Changing cell State

Cells are not static. They can transform themselves over time - but change can have dangerous implications. Non-cancerous cells, for example, can suddenly change into malignant ones.

That's one reason why researchers are trying to figure out why and how cells can shed their old identity and take on a new one. If they can figure out how this happens, scientists appears to better understand why a number of different cells - such as stem cells or cells that become malignant - transform. That, in turn, could someday allow researchers to control the transformative process in a way that might help treat a wide range of diseases.

Jeffrey Laney, assistant professor of biology at Brown University, has identified one way this change takes place by looking at Saccharomyces cerevisae, a common yeast used to make beer and bread. Laney observed that a cellular "machine" removes a regulatory "lid" from genes in the cell, so the cell can change its state. Details are published online in Nature Cell Biology, with a print version to come.

"We have known that cells shed their old identity. What we didn't know is how that mechanism occurred," said Laney, the paper's main author and a resaearcher in the Department of Molecular Biology, Cell Biology and Biochemistry.

The finding could shed new light on a number of different biological transitions, Laney said, where cells change or evolve as part of their normal functioning......... Posted by: Janet      Read more         Source

December 10, 2009, 7:49 AM CT

Tropical birds waited for land crossing

Despite their ability to fly, tropical birds waited until the formation of the land bridge between North and South America to move northward, as per a University of British Columbia study published this week in theProceedings of the National Academy of Sciences Early Edition.

"While a number of North American birds simply flew across the marine barriers that once separated the continents, tropical birds, particularly those in Amazon forest regions, began colonization of North America almost entirely after the completion of the land bridge," says main author Jason Weir, who conducted the study as part of his PhD at UBC.

"This study is the most extensive evidence to date that shows the land bridge playing a key role in the interchange of bird species between North and South America and the abundant biodiversity in the tropical regions," says Weir, now a post-doctoral fellow at the University of Chicago.

The Isthmus of Panama land bridge was completed between three and four million years ago, and today consists of the country of Panama. It is believed to have initiated the Great American Biotic Interchange, bringing mammals that evolved uniquely in South America during its "island isolation" - the armadillo, opossum and porcupine - to North America.

Fossil records have shown that mammalian species also travelled across the land bridge from North to South America, increasing biodiversity in the tropical regions. "But a lack of bird fossils has made it difficult to determine if the land bridge was equally instrumental in the interchange of avian species," says Weir......... Posted by: Kelly      Read more         Source

December 10, 2009, 7:39 AM CT

Population status of white marlin

The prized white marlin, sought by anglers in million dollar prize tournaments and captured incidentally in commercial fisheries, is among the most overfished marine species under international management and the subject of contentious debate on how to best achieve its recovery. Now a newly released study published recently in the journal Endangered Species Research casts uncertainty on the accuracy of current knowledge of white marlin biology and prior population evaluations, which form the basis of management and conservation policy. The study reports that the white marlin look-alike species, the enigmatic roundscale spearfish whose very existence was only confirmed three years ago makes up almost a third (approximately 27%) of the fish historically identified as white marlin. This previously unrealized, relatively high abundance of roundscale spearfish and their misidentification might have impacted past evaluations of white marlin population sizes and concomitant management efforts.

Given considerable concern about its declining populations, petitions to list the white marlin under the U.S. Endangered Species Act were considered in 2002 and 2007. Listing the fish would have undoubtedly put an end to white marlin fishing tournaments, which infuse millions of dollars into the recreational fishing industry as well as local economies......... Posted by: Kelly      Read more         Source

December 9, 2009, 11:37 PM CT

More than the origin

Eventhough Charles Darwin is most well-known for his book On the Origin of Species, in which he described the process of natural selection, he greatly contributed to a number of specific fields within biology. As the bicentennial anniversary of Darwin's birth comes to a close, the recent issue of the American Journal of Botany presents two papers exploring botanical history before the time of Darwin, Darwin's contributions to botany, and what researchers have discovered in the subsequent years following Darwin's first presentation of his a number of provocative ideas to the scientific community.

In "The 'Sensational Power' of Movement in Plants: A Darwinian System for Studying the Evolution of Behavior," Dr. Craig Whippo and Dr. Roger Hangarter discuss Darwin's research on plant movement (http://www.amjbot.org/cgi/content/full/96/12/2115). When Darwin first presented his theory of evolution, a number of opponents of the theory argued that evolution could not account for the acquisition of behavioral traits. Darwin believed that if he could present a materialistic basis for behavior, he could then explain how evolution acted on it. He used plant movements to test his theories of the evolution of behavior, and, as in a number of other areas of biology, Darwin's plant physiology research contributed to a paradigm shift in our understanding of the biological basis of insect, plant, and microbial behavior......... Posted by: Erica      Read more         Source

December 9, 2009, 11:27 PM CT

The Pitch of Blue Whale Songs is Declining

The sound level of songs blue whales sing across the vast expanses of the ocean to attract potential mates has been steadily creeping downward for the past few decades, and a scientist at Scripps Institution of Oceanography at UC San Diego and colleagues believe the trend appears to be good news for the population of the endangered marine mammal.

Mark McDonald of WhaleAcoustics in Bellvue, Colo., along with John Hildebrand of Scripps Oceanography and Sarah Mesnick of NOAA Fisheries Southwest Fisheries Science Center studied blue whale song data from around the world and discovered a downward curve in the pitch, or frequency, of the songs. The decline was tracked in blue whales across the globe, from off the Southern California coast to the Indian and Southern Oceans.

"The basic style of singing is the same, the tones are there, but the animal is shifting the frequency down over time. The more recent it is, the lower the frequency the animal is singing in, and we have observed that in every song we have data for," said Hildebrand, a professor of oceanography in the Marine Physical Laboratory at Scripps.

The study's results are reported in the most recent issue of the journal Endangered Species Research.

The scientists examined a list of possible causes for the frequency drop-from climate change to a rise in human-produced ocean noise-and believe it appears to be explained by the increase of blue whale numbers following bans on commercial whaling activities......... Posted by: Kelly      Read more         Source

December 2, 2009, 8:19 AM CT

Rhino poaching surges in Asia, Africa

Rhino poaching worldwide is on the rise, as per a new report by TRAFFIC and the International Union for the Conservation of Nature (IUCN).

The trade is being driven by Asian demand for horns and is made worse by increasingly sophisticated poachers, who now are using veterinary drugs, poison, cross bows and high caliber weapons to kill rhinos, the report states.

Since 2006 the majority (95 percent) of the poaching in Africa has occurred in Zimbabwe and South Africa, as per new data.

"These two nations collectively form the epicentre of an unrelenting poaching crisis in southern Africa," said Tom Milliken of TRAFFIC.

The report, which was submitted to the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) ahead of its 15th meeting of the Conference of the Parties (CoP15) in March, documents a decline in law enforcement effectiveness and an increase in poaching intensity in Africa. The situation is most serious in Zimbabwe where rhino numbers are now declining and the conviction rate for rhino crimes in Zimbabwe is only three percent. Despite the introduction of many new measures, poaching and illicit horn trade in South Africa has also increased.

"Concerted action at the highest level is needed to stop this global crisis of rampant rhino poaching," said Amanda Nickson, Director of the Species Programme at WWF International. "We call on the countries of concern to come to COP 15 in March with specific actions they have undertaken to show their commitment to stopping this poaching and protecting rhinos in the wild"......... Posted by: Kelly      Read more         Source

December 1, 2009, 8:18 AM CT

Shark fins and their geographic origin

1 Millions of shark fins are sold at market each year to satisfy the demand for shark fin soup, a Chinese delicacy, but it has been impossible to pinpoint which sharks from which regions are most threatened by this trade. Now, groundbreaking new DNA research has, for the first time, traced scalloped hammerhead shark fins from the burgeoning Hong Kong market all the way back to the sharks' geographic origin. In some cases the fins were found to come from endangered populations thousands of miles away. Published online today in the journal Endangered Species Research, the findings highlight the need to better protect these sharks from international trade, a move which will be considered by the Convention on International Trade in Endangered Species (CITES) at its March 2010 meeting in Qatar. The work was led by the Guy Harvey Research Institute and the Save Our Seas Shark Center at Nova Southeastern University and the Institute for Ocean Conservation Science at Stony Brook University.

The U.S. has proposed that CITES list the scalloped hammerhead and five other shark species under the organization's Appendix II, which would require permits for, and monitoring of, all trade in these species across international boundaries. Knowing the species and geographic origin of fins being traded would allow management and enforcement efforts to be allocated more effectively......... Posted by: Kelly      Read more         Source

November 25, 2009, 8:18 AM CT

Decline in Siberian tiger population

The Wildlife Conservation Society (WCS) announced recently a report revealing that the last remaining population of Siberian tigers has likely declined significantly due to the rising tide of poaching and habitat loss.

WCS says the report will help inform Russian officials of what needs to be done to protect remaining populations of the world's biggest cat.

The report was released by the Siberian Tiger Monitoring Program, which is coordinated by WCS in association with Russian governmental and non-governmental organizations. It revealed that a recent tiger survey over a representative part of the tiger's range showed a 40 percent decline in numbers from a 12-year average.

Annual tiger surveys are conducted at 16 monitoring sites scattered across tiger range to act as an early warning system to detect changes in the tiger population. The monitoring area, which covers 9,000 square miles (23,555 square kilometers), represents 15-18 percent of the existing tiger habitat in Russia. Only 56 tigers were counted at these monitoring sites. Deep snows this past winter may have forced tigers to reduce the amount they traveled, making them less detectable, but the report notes a 4-year trend of decreasing numbers of tigers......... Posted by: Kelly      Read more         Source

November 25, 2009, 8:09 AM CT

Global Study of Salmon

Popular thinking about how to improve food systems for the better often misses the point, as per the results of a three-year global study of salmon production systems. Rather than pushing for organic or land-based production, or worrying about simple metrics such as "food miles," the study finds that the world can achieve greater environmental benefits by focusing on improvements to key aspects of production and distribution.

For example, what farmed salmon are fed, how wild salmon are caught and the choice to buy frozen over fresh matters more than organic vs. conventional or wild vs. farmed when considering global scale environmental impacts such as climate change, ozone depletion, loss of critical habitat, and ocean acidification.

The study is the world's first comprehensive global-scale look at a major food commodity from a full life cycle perspective, and the scientists examined everything - how salmon are caught in the wild, what they're fed when farmed, how they're transported, how they're consumed, and how all of this contributes to both environmental degradation and socioeconomic benefits.

The scientists behind the study sought to understand how the world can develop truly sustainable food systems through the lens of understanding the complexities linked to wild and farmed salmon production, processing and distribution. They observed that decision-making for food must learn to fully account for the life cycle socioeconomic and environmental costs of food production. How we weight the importance of such impacts is ultimately subjective and in the realm of policy and culture, but using a comprehensive approach provides a more nuanced process for informed decision-making. Even food has a lifecycle, and the world must learn to comprehend the full costs of it in order to design reliable, resilient food systems to feed a world population that's forecast to grow to 9 billion in less than 40 years......... Posted by: Kelly      Read more         Source