tag:blogger.com,1999:blog-42054161462023630562024-03-05T15:39:12.039+07:00Delivery Biology Room DailyThe blog is all about of Biological Science : Cell Biology , Chemistry , Microbiology , Physiology ,
And Other Biological Study .Unknownnoreply@blogger.comBlogger181125tag:blogger.com,1999:blog-4205416146202363056.post-17997609972861767892009-01-05T22:27:00.004+07:002009-01-05T23:14:27.422+07:00New Breeding Ground For Endangered Whales? High Numbers Of Right Whales Seen In Gulf Of Maine<div style="text-align: justify;"><br /><br />A large number of North Atlantic right whales have been seen in the Gulf of Maine in recent days, leading right whale researchers at NOAA’s Northeast Fisheries Science Center to believe they have identified a wintering ground and potentially a breeding ground for this endangered species.<br /><br /><div style="text-align: center;"><a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEirudSPvvvaVkUyaGjWX8_zUdMYEuWOLp-vlNiKHFZUfGjPv0YqYg8Mj9k6t6NNhcQO-xVfdLwV3KI5HNQZ_TSuzvpc-jnyc6a6hE4cw0ogTWdla4ZZSm1lnnpQICvu0ECObKR_9dU5nZI/s1600-h/081231174309-large.jpg"><img style="margin: 0px auto 10px; display: block; text-align: center; cursor: pointer; width: 301px; height: 199px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEirudSPvvvaVkUyaGjWX8_zUdMYEuWOLp-vlNiKHFZUfGjPv0YqYg8Mj9k6t6NNhcQO-xVfdLwV3KI5HNQZ_TSuzvpc-jnyc6a6hE4cw0ogTWdla4ZZSm1lnnpQICvu0ECObKR_9dU5nZI/s320/081231174309-large.jpg" alt="" id="BLOGGER_PHOTO_ID_5287842839800874050" border="0" /></a><span style="font-size:85%;"><em>Three North Atlantic right whales are visible at the surface on Jordans Basin.<br />A fourth whale is visible just below the surface at lower left. (Credit: NOAA/Misty Niemeyer)</em><br /></span></div><br /></div><p style="text-align: justify;">The NEFSC’s aerial survey team saw 44 individual right whales on Dec. 3 in the Jordan Basin area, located about 70 miles south of Bar Harbor, Maine. Weather permitting, the team regularly surveys the waters from Maine to Long Island and offshore 150 miles to the Hague Line (the U.S.-Canadian border), an area about 25,000 square nautical miles.</p><div style="text-align: justify;"> </div><p style="text-align: justify;">“We’re excited because seeing 44 right whales together in the Gulf of Maine is a record for the winter months, when daily observations of three to five animals are much more common,” said Tim Cole, who heads the team. “Right whales are baleen whales, and in the winter spend a lot of time diving for food deep in the water column. Seeing so many of them at the surface when we are flying over an area is a bit of luck.” </p><div style="text-align: justify;"> </div><p style="text-align: justify;">Just a few days later, on Dec. 6, the team observed only three right whales on Cashes Ledge, about 80 miles east of Gloucester, Mass. Cole says the whales are known to be in the region, but actually seeing them on any given aerial survey is unpredictable. On Dec. 14, the team saw 41 right whales just west of Jordan Basin.</p><div style="text-align: justify;"> </div><p style="text-align: justify;">An estimated 100 female North Atlantic right whales head south in winter to give birth in the waters off Florida and Georgia, but little is known about where other individual right whales in the population go in winter, largely due to difficult surveying conditions.</p><div style="text-align: justify;"> </div><p style="text-align: justify;">Given the large geographical area over which North Atlantic right whales can occur, Cole and NEFSC colleagues developed an aerial grid system a few years ago for the Gulf of Maine and waters around Cape Cod to ensure complete coverage of the region. The grid resulted in consistent surveys of areas infrequently surveyed in the past, like Jordan Basin and the Great South Channel, and have shown that whales congregate in certain areas at certain times.</p><div style="text-align: justify;"> </div><p style="text-align: justify;">With a population estimated to be about 325 whales, knowing where the whales are at any time is critical to protect them. Finding an aggregation of whales can trigger a management action affording protection, such as slowing ship speeds in the vicinity of the whales. On Dec. 9, new federal speed rules for large ships went into effect to reduce ship strikes, to which North Atlantic right whales are particularly vulnerable.</p><div style="text-align: justify;"> </div><p style="text-align: justify;">NOAA understands and predicts changes in the Earth's environment, from the depths of the ocean to the surface of the sun, and conserves and manages our coastal and marine resources.</p><div style="text-align: justify;"><br /><br />SOURCE : National Oceanic And Atmospheric Administration<br /><br /><br /><br /></div>Unknownnoreply@blogger.com2tag:blogger.com,1999:blog-4205416146202363056.post-9924562634679569682009-01-05T22:14:00.006+07:002009-01-05T22:27:35.493+07:00Hot Southern Summer Threatens Coral With Massive Bleaching Event<div style="text-align: justify;"><br /><br />A widespread and severe coral bleaching episode is predicted to cause immense damage to some of the world’s most important marine environments over the next few months.<br /><br /><br /><div style="text-align: center;"><a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhPzclb-ytRCkII7_MpCcjkQ1FKCdbXFJOwl4sLsc-kNegBo5UoKFu5ocCrs8QQ_VCYGS7ktXnDm5MpiKrKJhZz8vOBaJZGdRM-BAQ7IZz_G_ZZEdck0fUdRPYIcnOk4yzjkQMNTXkqwgc/s1600-h/081228201342-large.jpg"><img style="margin: 0px auto 10px; display: block; text-align: center; cursor: pointer; width: 233px; height: 347px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhPzclb-ytRCkII7_MpCcjkQ1FKCdbXFJOwl4sLsc-kNegBo5UoKFu5ocCrs8QQ_VCYGS7ktXnDm5MpiKrKJhZz8vOBaJZGdRM-BAQ7IZz_G_ZZEdck0fUdRPYIcnOk4yzjkQMNTXkqwgc/s320/081228201342-large.jpg" alt="" id="BLOGGER_PHOTO_ID_5287831127088000706" border="0" /></a><span style="font-size:85%;"><em>A widespread and severe coral bleaching episode<br />is predicted to cause immense damage to some of the world's<br />most important marine environments over the next few months.<br />(Credit: iStockphoto/Tammy Peluso)</em></span><br /></div><br /></div><p style="text-align: justify;">A report from the US Government’s National Oceanic and Atmospheric Administration (NOAA) predicts severe bleaching for parts of the Coral Sea, which lies adjacent to Australia’s Great Barrier Reef, and the Coral Triangle, a 5.4 million square kilometre expanse of ocean in the Indo-Pacific which is considered the centre of the world’s marine life.</p><div style="text-align: justify;"> </div><p style="text-align: justify;">“This forecast bleaching episode will be caused by increased water temperatures and is the kind of event we can expect on a regular basis if average global temperatures rise above 2 degrees,” said Richard Leck, Climate Change Strategy Leader for WWF’s Coral Triangle Program.</p><div style="text-align: justify;"> </div><p style="text-align: justify;">The bleaching, predicted to occur between now and February, could have a devastating impact on coral reef ecosystems, killing coral and destroying food chains. There would be severe impacts for communities in Australia and the region, who depend on the oceans for their livelihoods.</p><div style="text-align: justify;"> </div><p style="text-align: justify;">The Coral Triangle, stretching from the Philippines to Malaysia and Papua New Guinea, is home to 75 per cent of all known coral species. More than 120 million people rely on its marine resources.</p><div style="text-align: justify;"> </div><p style="text-align: justify;">“Regular bleaching episodes in this part of the world will have a massive impact on the region’s ability to sustain local communities,” said Leck. “In the Pacific many of the Small Island Developing States, such as the Solomon Islands, rely largely on the coast and coastal environments such as coral reefs for food supply. This is a region where alternative sources of income and food are limited.</p><div style="text-align: justify;"> </div><p style="text-align: justify;">“Time is crucial and Australia needs to step up to the plate. Following the government’s lack of resolve to seriously reduce future domestic carbon emissions, Australia has a huge role to play in assisting Coral Triangle countries and people to adapt to the changes in their climate.“</p><div style="text-align: justify;"> </div><p style="text-align: justify;">The Australian government this week announced a 2020 target for reducing its greenhouse gas pollution by 5 per cent, which WWF criticised as completely inadequate. Reductions of at least 25 per cent by 2020 are needed to set the world on a pathway to meaningful cuts in greenhouse pollution.</p><div style="text-align: justify;"> </div><p style="text-align: justify;">Australia’s Coral Sea, which will also be affected by coral bleaching and climate change, is a pristine marine wilderness covering almost 1,000,000 square kilometres and is extraordinarily rich in marine life, including sharks and turtles, with a series of spectacular reefs rising thousands of metres from the sea floor.</p><div style="text-align: justify;"> </div><p style="text-align: justify;">WWF is urging the Australian government to declare the Coral Sea a marine protected area, as well as working to establish a network of marine protected areas that will assist ocean environments to adapt to the changes caused by rising temperatures, and to absorb the impacts from human activity.</p><br /><p style="text-align: justify;">SOURCE : World Wildlife Fund</p><br /><div style="text-align: justify;"><br /></div>Unknownnoreply@blogger.com0tag:blogger.com,1999:blog-4205416146202363056.post-15946711982575583822009-01-03T11:45:00.006+07:002009-01-03T13:49:58.038+07:00Structure Of New Botulism Nerve Toxin Subtype Revealed<p> </p><p align="center"><img id="BLOGGER_PHOTO_ID_5286955050755065090" style="DISPLAY: block; MARGIN: 0px auto 10px; WIDTH: 334px; CURSOR: hand; HEIGHT: 224px; TEXT-ALIGN: center" alt="" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgDAPfAZtohpVgtP6IDc1Ey9eyOu6XE5AvKmKipdpqyxRIk2I0Y-YetK8rZ3ZXor6WQlMKCuYi67ufHjrqwJbkfhIbHH6zlYFi1Duc55vx1aHbAZr4PoHLsOBwpCmRktjyhiI9ekTAWkj4/s320/081222163049-large.jpg" border="0" /><em><span style="font-size:85%;">Computer-generated “ribbon” representations of the molecular structure of botulinum neruotoxin subtypes E (left) and B (right). The accompanying schematics show that in subtype E, both the binding domain (yellow) and the catalytic domain (red — which cleaves cellular proteins to block the release of neurotransmitters) lie on one side of the translocation domain (green). On subtype B, the binding and catalytic domains flank the central translocation domain. This structural difference may explain why subtype E is a faster-acting toxin. (Credit: Image courtesy of DOE/Brookhaven National Laboratory)<br /></span></em></p><br /><br /><div align="justify">Scientists at the U.S. Department of Energy’s (DOE) Brookhaven National Laboratory have determined the atomic-level structure of a third subtype of botulinum neurotoxin — a deadly toxin produced by certain bacteria that causes the disease botulism, and is also used in cosmetic and therapeutic applications such as reducing wrinkles and calming a hyperactive bladder.<br /></div><br /><div align="justify">The detailed structure, published online December 22, 2008, by the Journal of Molecular Biology, reveals a unique arrangement of the active components that may help explain why botulinum neruotoxin subtype E (one of seven distinct subtypes) is faster-acting than other subtypes previously studied at Brookhaven Lab — and may have implications for improving vaccines and/or therapeutic agents.<br /></div><br /><div align="justify">“Understanding the differences among the seven botulinum neurotoxin subtypes is particularly imperative at a time of heightened concern about the potential use of these toxins as bioterror weapons,” said Brookhaven biologist and lead author Subramanyam Swaminathan, who has conducted extensive research on botulinum neurotoxins supported by DOE, the U.S. Army, and the National Institutes of Health. Although experimental vaccines administered prior to exposure can inhibit the neurotoxin’s destructive action, no effective pharmacological treatment exists.<br /></div><br /><div align="justify">All seven neurotoxin subtypes cause their deadly effects using a common mechanism, with each step being activated by a different portion, or domain, of the toxin protein. First the neurotoxin binds to a nerve cell; then it moves into the cell; and then it cleaves specific proteins that block the release of neurotransmitters, the chemicals nerve cells use to communicate with one another and with muscles. Without that communication, muscles, including those used to breathe, become paralyzed.<br /></div><br /><div align="justify">“Blocking any of these steps could thwart the toxins’ deadly action,” Swaminathan said. “But to do that, we need to understand the details of the proteins’ structures.”<br /></div><br /><div align="justify">Swaminathan and his team had previously analyzed the molecular-level structures of various fragments of botulinum neurotoxin subtypes A to F, and that of the whole neurotoxin B, using x-ray crystallography at the National Synchrotron Light Source (NSLS) at Brookhaven Lab. In this technique, scientists beam high-intensity x-rays at a crystalline sample of the protein and measure how the x-rays scatter off the sample to locate the positions of individual atoms.<br /></div><br /><div align="justify">These studies revealed that in subtypes A and B, the three domains were arranged in the same way: with the binding and protein-cleaving domains “flanking” a longer central region known as the translocation domain, essential for moving the toxin into the cell.<br /></div><br /><div align="justify">“Because the genes that code for these proteins have a large degree of similarity and all the subtypes incapacitate nerve cells in a very similar way, many biologists had assumed that all seven botulinum neurotoxins would have a similar structural arrangement,” Swaminathan said.<br />The current study of botulinum subtype E, also conducted at the NSLS, disproved that assumption, taking the scientists by surprise. Instead of the flanking arrangement, the binding and protein-cleaving domains of subtype E are both on the same side of the translocation domain. In addition, while all other subtypes are made of two protein chains, subtype E is a single-chain molecule.<br /></div><br /><div align="justify">“This arrangement may have an effect on translocation, with the molecule strategically positioned for quick entry into the cell,” Swaminathan said. Though he emphasizes that further confirming research is essential, this could be a plausible explanation for why botulism caused by subtype E sets in faster than that caused by other subtypes.<br /></div><br /><div align="justify">This finding may help scientists develop faster-acting vaccines and therapeutic agents.<br />For example, in the treatment of hyperactive bladder disorders, botulinum neurotoxin subtype A is currently used to inhibit neurotransmitter release and control bladder muscles. But it can take days or a week for the drug to be effective. A faster-acting neurotoxin might improve the response.<br /></div><br /><div align="justify">Additionally, patients sometimes develop resistance to botulinum treatments, developing antibodies that break down the toxin. So having an additional subtype for therapeutic use could be of benefit in situations where treatments must be repeated.<br /></div><br /><div align="justify">Finally, considering the threat of botulinum neurotoxin being used as a bioterror weapon, Swaminathan said, “The finding of a significant variation in the structural arrangement of subtype E also makes it clear that we must study the structures of the four remaining subtypes to gain a better understanding of their individual characteristics so that appropriate countermeasures can be developed for all seven forms.”<br /></div><br /><div align="justify">This study was funded by grants from the Defense Threat Reduction Agency/Joint Science and Technology Office for Chemical and Biological Defense. Data for this study were measured at beamline X25 of the NSLS, which is supported by the Offices of Biological and Environmental Research and of Basic Energy Sciences of DOE’s Office of Science, and from the National Center for Research Resources of the National Institutes of Health.</div><br /><div align="justify"></div><br /><div align="justify"></div><br /><div align="justify">SOURCE : DOE/Brookhaven National Laboratory </div><br /><div align="justify"></div><br /><div align="justify"></div><br /><div align="justify"></div>Unknownnoreply@blogger.com0tag:blogger.com,1999:blog-4205416146202363056.post-31206838902991552802009-01-03T01:51:00.001+07:002009-01-03T01:59:01.118+07:00Grape-seed Extract Kills Laboratory Leukemia Cells, Proving Value Of Natural Compounds<div align="justify"> </div><div align="justify"> </div><div align="justify"> </div><div align="justify">An extract from grape seeds forces laboratory leukemia cells to commit cell suicide, according to researchers from the University of Kentucky. They found that within 24 hours, 76 percent of leukemia cells had died after being exposed to the extract.<br />The investigators, who report their findings in the January 1, 2009, issue of Clinical Cancer Research, a journal of the American Association for Cancer Research, also teased apart the cell signaling pathway associated with use of grape seed extract that led to cell death, or apoptosis. They found that the extract activates JNK, a protein that regulates the apoptotic pathway.<br /></div><div align="justify">While grape seed extract has shown activity in a number of laboratory cancer cell lines, including skin, breast, colon, lung, stomach and prostate cancers, no one had tested the extract in hematological cancers nor had the precise mechanism for activity been revealed.<br /></div><div align="justify">"These results could have implications for the incorporation of agents such as grape seed extract into prevention or treatment of hematological malignancies and possibly other cancers," said the study's lead author, Xianglin Shi, Ph.D., professor in the Graduate Center for Toxicology at the University of Kentucky.<br /></div><div align="justify">"What everyone seeks is an agent that has an effect on cancer cells but leaves normal cells alone, and this shows that grape seed extract fits into this category," he said.<br /></div><div align="justify">Shi adds, however, that the research is not far enough along to suggest that people should eat grapes, grape seeds, or grape skin in excess to stave off cancer. "This is very promising research, but it is too early to say this is chemo-protective."<br /></div><div align="justify">Hematological cancers – leukemia, lymphoma and myeloma – accounted for an estimated 118,310 new cancer cases and almost 54,000 deaths in 2006, ranking these cancers as the fourth leading cause of cancer incidence and death in the U.S.<br /></div><div align="justify">Given that epidemiological evidence shows that eating vegetables and fruits helps prevent cancer development, Shi and his colleagues have been studying chemicals known as proanthocyanidins in fruits that contribute to this effect. Shi has found that apple peel extract contains these flavonoids, which have antioxidant activity, and which cause apoptosis in several cancer cell lines but not in normal cells. Based on those studies, and findings from other researchers that grape seed extract reduces breast tumors in rats and skin tumors in mice, they looked at the effect of the compound in leukemia cells.<br /></div><div align="justify">Using a commercially available grape seed extract, Shi exposed leukemia cells to the extract in different doses and found the marked effect in causing apoptosis in these cells at one of the higher doses.<br /></div><div align="justify">They also discovered that the extract does not affect normal cells, although they don't know why.<br /></div><div align="justify">The researchers then used pharmacologic and genetic approaches to determine how the extract induced apoptosis. They found that the extract strongly activated the JNK pathway, which then led to up-regulation of Cip/p21, which controls the cell cycle.<br /></div><div align="justify">They checked this finding by using an agent that inhibited JNK, and found that the extract was ineffective. Using a genetic approach – silencing the JNK gene – also disarmed grape seed extract's lethal attack in leukemia cells.<br /></div><div align="justify">"This is a natural compound that appears to have relatively important properties," Shi said.</div><div align="justify"> </div><div align="justify"> </div><div align="justify">SOURCE : American Association for Cancer Research </div><div align="justify"> </div><div align="justify"> </div><div align="justify"> </div>Unknownnoreply@blogger.com0tag:blogger.com,1999:blog-4205416146202363056.post-88183266935610349772009-01-03T01:31:00.005+07:002009-01-03T01:44:31.511+07:00Four Years After Tsunami, Coral Reefs Recovering<div align="justify"></div><br /><div align="justify"></div><br /><div align="justify"></div><br /><div align="justify">A team of scientists from the New York-based Wildlife Conservation Society (WCS) has reported a rapid recovery of coral reefs in areas of Indonesia, following the tsunami that devastated coastal regions throughout the Indian Ocean on December 26, 2004. </div><div align="justify"><br />The WCS team, working in conjunction with the Australian Research Council Centre of Excellence for Coral Reef Studies (ARCCoERS) along with government, community and non-government partners, has documented high densities of “baby corals” in areas that were severely impacted by the tsunami.<br /><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh00uAh5T74xTSFYNRrNeSrblrlrSslDZlygvRwKSsLsELInnyX5YpzvwuG8MnqNqjcjaxK2yh9zOUAT_K5z8tIFlyTP7qISjgiaObn38f3Ryunpi7JTFNMca02MoqPIdFc5MGiTyEDi-8/s1600-h/081227225250-large.jpg"><img id="BLOGGER_PHOTO_ID_5286768836226574770" style="FLOAT: right; MARGIN: 0px 0px 10px 10px; WIDTH: 290px; CURSOR: hand; HEIGHT: 197px" alt="" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh00uAh5T74xTSFYNRrNeSrblrlrSslDZlygvRwKSsLsELInnyX5YpzvwuG8MnqNqjcjaxK2yh9zOUAT_K5z8tIFlyTP7qISjgiaObn38f3Ryunpi7JTFNMca02MoqPIdFc5MGiTyEDi-8/s320/081227225250-large.jpg" border="0" /></a></div><br /><div align="justify">The team, which has surveyed the region’s coral reefs since the December 26, 2004 tsunami, looked at 60 sites along 800 kilometers (497 miles) of coastline in Aceh, Indonesia. The researchers attribute the recovery to natural colonization by resilient coral species, along with the reduction of destructive fishing practices by local communities.<br /></div><br /><div align="justify"></div><br /><div align="justify">“On the 4th anniversary of the tsunami, this is a great story of ecosystem resilience and recovery,” said Dr, Stuart Campbell, coordinator of the Wildlife Conservation Society’s Indonesia Marine Program. “Our scientific monitoring is showing rapid growth of young corals in areas where the tsunami caused damage, and also the return of new generations of corals in areas previously damaged by destructive fishing. These findings provide new insights into coral recovery processes that can help us manage coral reefs in the face of climate change.”<br /></div><br /><div align="justify">While initial surveys immediately following the tsunami showed patchy (albeit devastating) damage to coral reefs in the region, surveys in 2005 indicated that many of the dead reefs in the study area had actually succumbed long ago to destructive fishing practices such as the use of dynamite and cyanide to catch fish. It is also possible that the crown of thorns starfish—a marine predator—had caused widespread coral mortality.<br /></div><br /><div align="justify"></div><br /><div align="justify">Since then, some communities have moved away from destructive fishing and have even begun transplanting corals to recover damaged areas.<br /></div><br /><div align="justify">For example, Dodent Mahyiddin, a dive operator on Weh Island, leads an effort to transplant corals onto hand-laid underwater structures to restore a badly damaged reef in front of the remains of his dive shop, which was also destroyed by the tsunami. Already he is seeing widespread colonization of young corals.<br /></div><br /><div align="justify"></div><br /><div align="justify">On a larger scale, the WCS team is working to establish community-based coral reef protected areas based on customary marine laws that were first established in the 1600’s and maintained throughout Dutch colonial rule. The laws empower local communities to manage their own local marine resources rather than adhere to nationalized protected areas.<br /></div><br /><div align="justify">Healthy coral reefs are economic engines for Acehnese communities, according to WCS, supplying commercially valuable food fish as well as tourism dollars from recreational diving.<br /></div><br /><div align="justify"></div><br /><div align="justify">“The recovery, which is in part due to improved management and the direct assistance of local people, gives enormous hope that coral reefs in this remote region can return to their previous condition and provide local communities with the resources they need to prosper,” said Dr. Campbell. “The recovery process will be enhanced by management that encourages sustainable uses of these ecosystems and the protection of critical habitats and species to help this process.”<br /></div><br /><div align="justify">The study area is adjacent to the “Coral Triangle,” a massive region containing 75 percent of the world’s coral species shared by Indonesia, Malaysia, Papua New Guinea, Philippines, Solomon Islands, and Timor-Leste.</div><br /><div align="justify"></div><br /><div align="justify"></div><br /><div align="justify">SOURCE : Wildlife Conservation Society.</div><div align="justify"> </div><div align="justify"> </div>Unknownnoreply@blogger.com0tag:blogger.com,1999:blog-4205416146202363056.post-33088944765990198162008-08-20T20:21:00.000+07:002008-08-20T20:21:00.480+07:00In Promiscuous Antelopes, The 'Battle Of The Sexes' Gets Flipped<div style="text-align: justify;"><br /><br />In some promiscuous species, sexual conflict runs in reverse, reveals a new study. Among African topi antelopes, females are the ones who aggressively pursue their mates, while males play hard to get.</div><p style="text-align: justify;">The classical view of sexual conflict holds that males, for whom reproducing is cheap, will mate as much as possible. On the other hand, females, who must pay a heftier price, are choosier about their mating partners.</p><p style="text-align: justify;"><br /></p><p style="text-align: justify;"><a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEggTI-Kf9fwHxYnphXA9gk2lmspZAoNQDsn6kQJLlZbqdyZumZOLlpLw8W63T_1wAhq84dzLofjq6Q9zy0DQFhLou9hRo3s6b4COKY54fUu8CuMUCZJT-XhtQR5QsQpBn2hNsrhjM7YVCQ/s1600-h/071129100050-large.jpg"><img style="margin: 0px auto 10px; display: block; text-align: center; cursor: pointer;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEggTI-Kf9fwHxYnphXA9gk2lmspZAoNQDsn6kQJLlZbqdyZumZOLlpLw8W63T_1wAhq84dzLofjq6Q9zy0DQFhLou9hRo3s6b4COKY54fUu8CuMUCZJT-XhtQR5QsQpBn2hNsrhjM7YVCQ/s320/071129100050-large.jpg" alt="" id="BLOGGER_PHOTO_ID_5233621596351110914" border="0" /></a></p><div style="text-align: justify;"> </div><p style="text-align: center;"><span style="font-size:85%;"><em>Mother nursing baby topi antelope in Serengeti National Park in Tanzania,<br />East Africa. (Credit: iStockphoto/Bruce Block)</em></span></p><p style="text-align: justify;"><br /></p><p style="text-align: justify;">"When biologists talk about the 'Battle of the Sexes,' they often tacitly assume that the battle is between persistent males who always want to mate and females who don't," said Jakob Bro-Jørgensen of University of Jyväskylä in Finland. "However, in topi antelopes, where females are known to prefer to mate with males in the center of mating arenas, we've found a reversal of these stereotypic sex roles."</p><div style="text-align: justify;"> </div><p style="text-align: justify;">Such role reversals may occur in species where females benefit from mating multiply, either because it increases their chances of conception with high-quality males or simply because it increases the probability that they conceive at all, Bro-Jørgensen added. He noted that this reversed sexual conflict might not be a rarity in the animal kingdom, as topi are "in many ways a very typical mammalian species characterized by male mate competition and female choice."</p><div style="text-align: justify;"> </div><p style="text-align: justify;">In promiscuous species--those in which individuals mate with multiple partners within a short time period--Bro-Jørgensen's group suspected that females might sometimes have higher optimum mating rates than their mating partners. Topi antelope offered an ideal opportunity for studying the dynamics of sex roles in promiscuous mammals, Bro-Jørgensen said, because over a month and a half, individual females become receptive to mating for roughly one day, when they mate several times with each of about four males on average. Females prefer to mate with those males who have succeeded in acquiring territories in the center of "mating arenas," known as leks. But the majority of females also mate with other males as well, resulting in intense sperm competition.</p><div style="text-align: justify;"> </div><p style="text-align: justify;">Indeed, they have now shown that aggressive female topis compete with one another for a limited supply of sperm from the most desirable members of the opposite sex, even attacking their fellow mating pairs. Meanwhile, resistant males grow choosier about their mating partners, deliberately selecting the least mated females and launching counterattacks against aggressive females with whom they've already mated.</p><div style="text-align: justify;"> </div><p style="text-align: justify;">The bottom-line of the findings, according to Bro-Jørgensen: "We should not regard coyness as the only natural female sex role just as we should not expect that it is always the natural male sex role to mindlessly accept any mating partner," he said. "Nature favors a broader range of sex roles."</p><div style="text-align: justify;"> </div><p style="text-align: justify;">This research was published online on November 29th in Current Biology.</p><div style="text-align: justify;"> </div><p style="text-align: justify;">The researcher is Jakob Bro-Jørgensen, of the Department of Biological University of Jyva¨ skyla, Jyva¨ skyla¨, Finland; and the Institute of Zoology, Zoological Society, Regent's Park, London, UK.</p><div style="text-align: justify;"><br /><br />SOURCE : Cell Press<br /><br /><br /></div>Unknownnoreply@blogger.com0tag:blogger.com,1999:blog-4205416146202363056.post-35746846705747287702008-08-20T11:19:00.001+07:002008-08-20T11:19:00.519+07:00Protein Translation In Sperm<div style="text-align: justify;"><br /><br />A new paper in the February 15th issue of Genes & Development lends novel insight into the cellular changes that occur in sperm while they reside in the female reproductive tract -- providing a new understanding of the molecular genetics of successful fertilization.</div><p style="text-align: justify;">It had been believed for decades that spermatozoa are translationally silent. However, Dr. Yael Gur and Haim Breitbart (Bar-Ilan University, Israel) now show that, in fact, protein translation does take place in mammalian sperm prior to fertilization. </p><div style="text-align: justify;"> </div><p style="text-align: justify;">Their paper has been released online ahead of print at www.genesdev.org. </p><div style="text-align: justify;"> </div><p style="text-align: justify;">After ejaculation, sperm reside in the female reproductive tract for several hours. During this time, a number of biochemical changes take place within sperm, collectively known as "capacitation," that render the sperm competent to penetrate and fertilize the female oocyte. </p><div style="text-align: justify;"> </div><p style="text-align: justify;">In their new report, Drs. Gur and Breitbart demonstrate that human, rat, bovine and mouse sperm all incorporate labeled amino acids into polypeptides during the capacitation phase. They identify that mitochondrial translation machinery (as opposed to cytoplasmic) directs translation of nuclear-encoded genes in sperm, and that its inhibition leads to a marked decrease in sperm motility, actin polymerization, the acrosome reaction and in vitro fertilization rates. </p><div style="text-align: justify;"> </div><p style="text-align: justify;">Thus, protein translation in sperm is essential for sperm functions that directly contribute to fertilization. Dr. Breitbart is confident that "The new findings would give us better understanding for treatment of male infertility and developing new male or female contraceptives." </p><div style="text-align: justify;"><br /><br />SOURCE : Cold Spring Harbor Laboratory<br /><br /><br /></div>Unknownnoreply@blogger.com0tag:blogger.com,1999:blog-4205416146202363056.post-9630778522749284572008-08-19T20:51:00.002+07:002008-08-19T20:51:00.468+07:00Male Deer Are Born To Live Fast, Die Young<div style="text-align: justify;"><br /><br />In the September issue of The American Naturalist, Juan Carranza (Biology and Ethology Unit, University of Extremadura, Spain) and Javier Pérez-Barbería (Macaulay Institute, United Kingdom) offer a new explanation for why males of ungulate species subjected to intense competition are born with lower survival expectancies than females.</div><p style="text-align: justify;">The research reveals that male ungulates have smaller molars relative to their body size -- and hence less durable teeth that will wear out sooner, which might contribute to their shorter lives compared with females.</p><div style="text-align: justify;"> </div><p style="text-align: justify;">Natural selection favors reproduction rather than survival; the cost of reproduction compromises survival. Males of species subjected to intense male-male competition for access to females are known to have shorter life expectancies than females. Earlier aging in males might be related to higher reproductive costs, especially when lifetime reproductive success in males takes place within the few years when they can win contests and maintain their dominance. </p><div style="text-align: justify;"> </div><p style="text-align: justify;">By comparing body and dental size of males and females of 123 species of ungulates, the authors offer another compelling explanation for why male ungulates lead shorter lives. They estimated the pattern of change of these traits along the evolutionary development of the group and found that for species where a single male has many females and where the males and females are different sizes, the rate of increase of dental size was lower than that of body size. </p><div style="text-align: justify;"> </div><p style="text-align: justify;">As a result, smaller teeth (in comparison to body size) are produced in males. It is possible that natural selection did not produce larger, more durable teeth because there was no reproductive return from it, since males in these species do not generally increase their success by living longer after prime age. </p><div style="text-align: justify;"> </div><p style="text-align: justify;">"These findings," the authors state, "provide us with interesting insights into how natural and sexual selection design our bodies and their longevity." </p><div style="text-align: justify;"> </div><p style="text-align: justify;">Reference: Juan Carranza and F. Javier Pérez-Barbería, "Sexual selection and senescence: male size-dimorphic ungulates evolved relatively smaller molars than females", The American Naturalist (2007) volume 170:370--380. DOI: 10.1086/519852</p><div style="text-align: justify;"><br />SOURCE : University of Chicago Press Journals<br /><br /><br /></div>Unknownnoreply@blogger.com0tag:blogger.com,1999:blog-4205416146202363056.post-86583771933214883502008-08-19T18:54:00.002+07:002008-08-19T18:54:00.791+07:00The Cost Of Keeping Eggs Fresh For Mother Cockroaches<div style="text-align: justify;"><br /><br />Tiny multiple sperm can be long lived, while large "expensive" eggs degenerate quickly if they are not fertilized. This conundrum -- there should be selection for females to keep their eggs fresh until they are used -- has recently been studied in a cockroach where some choosy females have genes that allow them to maintain eggs while looking for the best mate. Perhaps, however, these genes are limited because they are harmful in some environments.</div><br /><p style="text-align: justify;"><a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhhgbvi9PMxQaJQy3MrJBR-UEk1vbLmOOQWLpWhbE1nSUjNTZD73zzx3ZhNcajE-9XbCFELIPBkX-O0v7L4RWfyRNp8RrIu22FTiFedGngTL-qiW4XH_EtFFX6Uj4qNgat7RMxO5vp4LUM/s1600-h/070227105430.jpg"><img style="margin: 0pt 10px 10px 0pt; float: left; cursor: pointer; width: 209px; height: 157px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhhgbvi9PMxQaJQy3MrJBR-UEk1vbLmOOQWLpWhbE1nSUjNTZD73zzx3ZhNcajE-9XbCFELIPBkX-O0v7L4RWfyRNp8RrIu22FTiFedGngTL-qiW4XH_EtFFX6Uj4qNgat7RMxO5vp4LUM/s320/070227105430.jpg" alt="" id="BLOGGER_PHOTO_ID_5233630379596248754" border="0" /></a>One of the defining differences between the sexes is in the size of their gametes. Males make many tiny sperm while females make only a few large eggs. This suggests that sperm are cheap while eggs are expensive. Yet sperm can be very long lived, while eggs degenerate quickly after they are made if they are not fertilized.</p><div style="text-align: justify;"> </div><p style="text-align: justify;">Why don't females take better care of their expensive eggs? After all, if the females don't use their eggs they have fewer offspring, whereas males make more sperm then they will use anyway. This evolutionary conundrum -- there should be selection for females to keep their eggs fresh until they are used -- has recently been studied by Dr. Trish Moore and her colleagues at the Cornwall Campus of the University of Exeter, with support from NERC, and is published in the March issue of The American Naturalist.</p><div style="text-align: justify;"> </div><p style="text-align: justify;">Moore and colleagues examined why females don't keep their eggs fresh in a cockroach where females mate only once during a reproductive cycle, give live birth, and therefore are choosy about the male with which they will mate. Females can't be too choosy, however. If they wait too long to mate they lose good quality oocytes through programmed cell death. But Moore's team finds that some females have genes that would allow them to maintain eggs even if they delay mating. So why aren't all females delaying cell death and holding onto their eggs? Moore speculates that perhaps these genes play a dual role and while they may be beneficial under one environment, when females don't mate, they might be harmful under another, such as when food is limiting. "When females are starving, hanging on to yolky eggs full of nutrients is bad. </p><div style="text-align: justify;"> </div><p style="text-align: justify;">Instead a female could recycle those nutrients into her survival. So females face a decision between keeping eggs fresh for producing offspring now, or using those nutrients herself and taking the chance she can reproduce later." The group is currently investigating this trade-off arising from a conflict over food or sex. Although this is a new twist in the conflict over food or sex, the result is a familiar one in evolutionary biology; it is hard to be best at everything.</p><div style="text-align: justify;"><br /><br />SOURCE : University of Chicago Press Journals<br /><br /><br /></div>Unknownnoreply@blogger.com0tag:blogger.com,1999:blog-4205416146202363056.post-88566701540484695832008-08-18T20:40:00.003+07:002008-08-18T20:40:00.395+07:00Male Chimpanzees Prefer Mating With Old Females<div style="text-align: justify;"><br /><br />Researchers studying chimpanzee mating preferences have found that although male chimpanzees prefer some females over others, they prefer older, not younger, females as mates.<br /><br /><br /><a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEis4O6mCGa-A8_wVdaZ8IMItQ4DJZ__18hF4eKG1U6AYGnIMfrVIwHLhXmL-bJ_QR6FQXtZ1PFxYQETBXJWa3HaeU6G5p4ALoPq8k0lc1lBBLYgR6thb-X0IXdzkry2NxZZQOdwEOE4zgk/s1600-h/061120130545.jpg"><img style="margin: 0px auto 10px; display: block; text-align: center; cursor: pointer; width: 199px; height: 257px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEis4O6mCGa-A8_wVdaZ8IMItQ4DJZ__18hF4eKG1U6AYGnIMfrVIwHLhXmL-bJ_QR6FQXtZ1PFxYQETBXJWa3HaeU6G5p4ALoPq8k0lc1lBBLYgR6thb-X0IXdzkry2NxZZQOdwEOE4zgk/s320/061120130545.jpg" alt="" id="BLOGGER_PHOTO_ID_5233626636462191362" border="0" /></a></div><p style="text-align: center;"><span style="font-size:85%;"><em>Imoso, the highest-ranking male in the Kanyawara community of Kibale National Park,<br />Uganda, grooms Outamba, a middle-aged female. Male chimpanzees at Kanyawara consistently prefer the oldest females in their community as mating partners, suggesting that the preference that human men exhibit for youthful women is a recent evolutionary phenomenon. For more information, see the Report by Muller et al. in the November 21 Current Biology. (Credit: Photograph by Jean-Michel Krief)</em></span></p><p style="text-align: center;"><span style="font-size:85%;"><em><br /></em></span></p><p style="text-align: justify;">The findings uncover a stark contrast between chimpanzee behavior and that of humans, their primate cousins. The basis for this difference may lie in the fact that whereas chimpanzees participate in a relatively promiscuous mating system, humans form unusually long-term mating bonds, thereby making young females more valuable as mates with greater reproductive potential. The findings, reported by Martin Muller of Boston University and colleagues at Harvard University, appear in the November 21st issue of Current Biology.</p><div style="text-align: justify;"> </div><p style="text-align: justify;">Theoretical explanations for the preference of human males for young females as mates include the facts that humans tend to form long-term mating partnerships, and that female fertility is limited by menopause and, therefore, age. The converse of such an explanation suggests that species that appear to lack long-term pair bonding and menopause (such as chimpanzees) should not exhibit such strong preferences by males for young females.</p><div style="text-align: justify;"> </div><p style="text-align: justify;">In the new work, researchers examined this idea by studying male mate preferences within the Kanyawara chimpanzee community in Kibale National Park in Uganda. The researchers found that, in contrast to humans, male chimpanzees prefer older females to younger ones. They found that, compared to younger females, older females were more likely to be approached for copulation, were more often in association with males during estrous periods, copulated more frequently with high-ranking males, and gave rise to higher rates of male-on-male aggression in mating contests.</p><div style="text-align: justify;"> </div><p style="text-align: justify;">The findings, in addition to supporting the idea that long-term pair bonding and menopause may contribute to the preference of human males for young females, also suggest that this characteristic may be an evolutionarily derived trait that arose in the human lineage sometime after the lineages giving rise to humans and chimpanzees diverged. </p><div style="text-align: justify;"> </div><p style="text-align: justify;">The researchers include Martin N. Muller of Boston University in Boston, MA; Melissa Emery Thompson and Richard W. Wrangham of Harvard University in Cambridge, MA. The research at Kibale was supported by grants from the United States National Science Foundation (grant no. 0416125), the L.S.B. Leakey Foundation, the National Geographic Society, and the Wenner-Gren Foundation.</p><div style="text-align: justify;"> Muller et al.: "Male Chimpanzees Prefer Mating with Old Females." Publishing in Current Biology 16, 2234--2238, November 21, 2006 DOI 10.1016/j.cub.2006.09.042.<br /><br /><br />SOURCE : Current Biology<br /><br /><br /><br /></div>Unknownnoreply@blogger.com0tag:blogger.com,1999:blog-4205416146202363056.post-85450083508383337572008-08-18T08:47:00.002+07:002008-08-18T08:47:00.924+07:00Mouse Ovaries And Testes Age In Unique Ways<div style="text-align: justify;"><br /><br />Aging leads to large changes in gene activity in the ovaries of mice, but only limited changes in testes, according to new research. A lifespan-extending calorie-restricted diet reversed some of the aging effects -- but, unlike the widespread changes observed in somatic organs, it had an impact only in a small number of gonad-specific genes.</div><p style="text-align: justify;">As well as tackling one of the key questions of ageing -- by exploring if reproductive organs age in the same way as other body organs -- this research is important in the light of the trend for some women in developed countries to put off childbearing until later in life.</p><div style="text-align: justify;"> </div><p style="text-align: justify;">A research team led by Minoru Ko, MD, PhD, from the National Institute on Aging, Baltimore, USA used whole-genome DNA microarrays to study the effects of age, sex and diet on the global gene expression in mouse ovaries and testes. They found that reproductive organs age in a different way to other body tissues and, furthermore, that ovaries age in a different way from testes.</p><div style="text-align: justify;"> </div><p style="text-align: justify;">Age-related changes in gene expression occurred in gonads -- as they are known to in other body tissues -- but these changes tended to be in different classes of genes. Only two of the six categories of genes previously associated with aging in muscle, kidney and brain were associated with aging in the ovary; none were associated with aging in the testis. The changes seen in ovaries could be influenced by changes in the tissue composition of ovaries as females age and ovulation ceases.</p><div style="text-align: justify;"> </div><p style="text-align: justify;">The researchers also found that calorie restriction in females reduced the expression of genes involved in metabolism and follicle growth, which seems to be consistent with a popular view that the calorie restriction causes a shift in energy use away from reproduction towards general body maintenance and repair. However, male mice on the same diet did not appear to sacrifice reproductive function, suggesting an evolutionary difference between males and females when coping with a food shortage.</p><div style="text-align: justify;"><br /><br />SOURCE : BioMed Central<br /><br /><br /></div>Unknownnoreply@blogger.com0tag:blogger.com,1999:blog-4205416146202363056.post-19161108789603920322008-08-17T19:14:00.000+07:002008-08-17T19:14:00.778+07:00Alarm Pheromone Causes Aphids To Sprout Wings<div style="text-align: justify;"><br /><br />Chemical communication within insect species is often much more sophisticated than expected. When aphids are attacked by predators such as ladybird beetles, they release an alarm pheromone, (E)-β-farnesene, that has long been known to cause other aphids to walk around or drop from the plant.</div><p style="text-align: justify;">In a paper soon to appear in Ecology Letters, researchers at the University and Max-Planck-Institute in Jena, Germany, now show that exposure to alarm pheromone also causes pea aphids to produce winged offspring that leave their host plant when mature. Because some plants can also release (E)-β-farnesene, they could in theory manipulate aphids into flying away. </p><div style="text-align: justify;"> </div><p style="text-align: justify;"> However, aphids were shown to react mainly to the frequency of pheromone release and not the actual quantity present, possibly to avoid manipulation by plants. Thus, to reduce damage caused by aphids, the major insect pests in Europe, it may prove effective to apply pulses of alarm pheromone to infested fields.</p><div style="text-align: justify;"><br /><br />SOURCE : Blackwell Publishing Ltd.<br /><br /><br /></div>Unknownnoreply@blogger.com0tag:blogger.com,1999:blog-4205416146202363056.post-8639004552811727292008-08-17T09:34:00.003+07:002008-08-17T09:34:00.212+07:00Men And Women May Need Different Diets<div style="text-align: justify;"><br /><br />Diet can strongly influence how long you live and your reproductive success, but now scientists have discovered that what works for males can be very different for females.</div><p style="text-align: justify;">In the first study of its kind, the researchers have shown that gender plays a major role in determining which diet is better suited to promoting longer life or better reproductive success.</p><div style="text-align: justify;"> </div><p style="text-align: justify;">In the evolutionary "battle of the sexes", traits that benefit males are costly when expressed in females and vice versa. This conflict may have implications for human diet, aging and reproduction, says a team of scientists from UNSW, the University of Sydney and Massey University.<a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhCT9bk1pjb6RhhSZpk54L3ZyYtb5D-49bVVlRenh1wLEPo50WmV3ndC4lCzJUAyTqxjNZJo4s9j11mFs_GbsE9ZFhWJV6Zyzg_CoWYGkE_9U_8ZdjJc3OMBxPpr3jIMuGUMlzmFjAlbZE/s1600-h/080716121351.jpg"><img style="margin: 0pt 0pt 10px 10px; float: right; cursor: pointer; width: 190px; height: 283px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhCT9bk1pjb6RhhSZpk54L3ZyYtb5D-49bVVlRenh1wLEPo50WmV3ndC4lCzJUAyTqxjNZJo4s9j11mFs_GbsE9ZFhWJV6Zyzg_CoWYGkE_9U_8ZdjJc3OMBxPpr3jIMuGUMlzmFjAlbZE/s320/080716121351.jpg" alt="" id="BLOGGER_PHOTO_ID_5233625383764368130" border="0" /></a></p><div style="text-align: justify;"> </div><p style="text-align: justify;">"When it comes to choosing the right diet, we need to look more closely to the individual, their sex and their reproductive stage in life," says Associate Professor Rob Brooks, Director of the Evolution and Ecology Research Centre at the University of New South Wales. "It may be, for example, that women in their child-bearing years need a different diet to those who are post-menopausal.</p><div style="text-align: justify;"> </div><p style="text-align: justify;">"It also underlines the important lesson that what we want to eat or, if you like, what we're programmed to eat, is not necessarily best for us." The researchers are conducting long-term studies on Australian black field crickets and have discovered that the lifespan of both males and females is maximised on high-carbohydrate, low-protein diets, they say in the latest issue of Current Biology.</p><div style="text-align: justify;"> </div><p style="text-align: justify;">But reproductive success differs dramatically between the sexes when the carbohydrate-protein balance is changed: males live longest and have the greatest reproductive success with a diet that favours carbohydrates to protein by eight-to-one, whereas females have greatest success when the ratio is just one-to-one. Given a choice, however, females eat only a small amount more protein than males. The shared ability to sense and choose food dooms both males and females to eat a diet that is a compromise between what is best for each sex.</p><div style="text-align: justify;"> </div><p style="text-align: justify;">"Male and female crickets maximise their fitness on different diets," says UNSW's Dr Alexei Maklakov, the study's lead author. "Despite that, the dietary preferences of the sexes are very similar. Instead of selecting foods in a sex-specific manner, males and females select 'intermediate' diets that are less than optimal for both sexes.</p><div style="text-align: justify;"> </div><p style="text-align: justify;">The researchers believe the sexes share most of their genes and this fact can constrain the evolution of sex differences in traits such as diet choice, because many of the same genes are likely to be responsible for trait expression in both sexes.</p><div style="text-align: justify;"> </div><p style="text-align: justify;">Significance for humans -- "Men and women invest differently in reproduction, a difference that is even more marked than that between male and female crickets," says Rob Brooks. "Think of the tremendous amounts of energy and protein required of a mother in carrying a baby to term and breastfeeding. We also know that men and women need to eat different diets - think of the careful attention we pay to what expectant mothers eat.</p><div style="text-align: justify;"> </div><p style="text-align: justify;">"What men and women need to eat might be more dramatically different than we had realised. However, men and women eat very similar diets and our results suggest that our tastes and food preferences could be a shared compromise, as they are in crickets."</p><div style="text-align: justify;"><br /><br />SOURCE : University of New South Wales<br /><br /><br /></div>Unknownnoreply@blogger.com0tag:blogger.com,1999:blog-4205416146202363056.post-32999451482444167082008-08-17T09:00:00.002+07:002008-08-17T09:00:01.038+07:00Rodent Sperm Work Together For Better Results<div style="text-align: justify;"><br /><br />Individual sperm in promiscuous rodents have learned to work together in order to compete against sperm of rival males, according to new research carried out at the University of Sheffield</div><p style="text-align: justify;">Although, sperm are inseminated in millions each sperm goes it alone. However, under some circumstances it might be advantageous for sperm to cooperate with one another. This is especially likely to be the case when females are promiscuous and sperm of one male have to compete against those of rival males. New research by Dr Simone Immler and colleagues from the University's Department of Animal and Plant Sciences shows that in promiscuous rat and mice, where competition is high, individual sperm cooperate with one another in order to out-compete sperm of rival males.</p><div style="text-align: justify;"> </div><p style="text-align: justify;">The research shows that this cooperation is possible only because of to the highly specialised design of rat and mouse sperm. Promiscuous species have a particularly well developed 'hook shaped' sperm head which helps individual sperm to hook up to each other and form a 'group'. These groups of sperm contain five to 100 sperm and they swim faster and stronger than individual sperm which makes them better competitors in the race for the fertilisation of the egg. </p><div style="text-align: justify;"> </div><p style="text-align: justify;">Dr Simone Immler said: "It was previously believed that sperm not only competed against rival males but that they also competed against each other in order to fertilise the female egg. However, this research shows that when the pressure from rival males is high, individual sperm will cooperate with one another to ensure that at least one of their siblings successfully reaches the female egg."</p><div style="text-align: justify;"> </div><p style="text-align: justify;">The results will be published on Wednesday 24th January in the freely available, open-access journal -- online at <a target="_blank" href="http://www.plosone.org/" rel="nofollow">http://www.plosone.org</a>.</p><div style="text-align: justify;"> </div><p style="text-align: justify;">Citation: Immler S, Moore HDM, Breed WG, Birkhead TR (2007) By Hook or by Crook? Morphometry, Competition and Cooperation in Rodent Sperm. PLoS ONE 2(1): e170. doi:10.1371/journal.pone.0000170 (<a target="_blank" href="http://dx.doi.org/10.1371/journal.pone.0000170" rel="nofollow">http://dx.doi.org/10.1371/journal.pone.0000170</a>)</p><div style="text-align: justify;"><br /><br />SOURCE : Public Library of Science<br /><br /><br /><br /></div>Unknownnoreply@blogger.com0tag:blogger.com,1999:blog-4205416146202363056.post-39790325270415953532008-08-16T19:14:00.000+07:002008-08-16T19:14:00.145+07:00A Little Bit Of Egg Makes Tracking Aphids Easier<div style="text-align: justify;"><br /><br />The green peach aphid, despite its name, is a pest of potatoes. Besides siphoning off juices from potato plants, the aphid can infect the plants with viruses that cause an estimated $100 million annually in yield losses.<br /><br /><br /><div style="text-align: center;"><a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgAYUu6gvUYGGnmmv6xm9cQiMufY5-7ldAuYDJLwgll8bR6R56h_J9HKcHRq_7A4jZX2Q99ozK53GxZmq9gD6e6RhpARRXg8dGSEungi7bE55KYhy6cxz33Uw0DxPKJ-_-b5aw6MiULFC8/s1600-h/080527120756.jpg"><img style="margin: 0px auto 10px; display: block; text-align: center; cursor: pointer;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgAYUu6gvUYGGnmmv6xm9cQiMufY5-7ldAuYDJLwgll8bR6R56h_J9HKcHRq_7A4jZX2Q99ozK53GxZmq9gD6e6RhpARRXg8dGSEungi7bE55KYhy6cxz33Uw0DxPKJ-_-b5aw6MiULFC8/s200/080527120756.jpg" alt="" id="BLOGGER_PHOTO_ID_5233605236222170338" border="0" /></a><span style="font-size:85%;"><em>An alate (winged) green peach aphid, Myzus persicae. (Credit: Photo by Scott Bauer)</em></span><br /></div><br /></div><p style="text-align: justify;"><br /></p><p style="text-align: justify;">Now, tracking where and when the aphid is likely to transmit potato viruses could be easier to do, thanks to a new marker technique devised by Agricultural Research Service (ARS) entomologist Tom Unruh. His approach--which uses egg whites, plastic-mesh screens and an antibody-based test--is still experimental. But, ultimately, information derived from its use could help potato growers improve the timing of insecticide application to deter virus-laden aphids from feeding on plants.</p><div style="text-align: justify;"> </div><p style="text-align: justify;">Unruh devised the technique to support studies to determine whether virus-carrying aphids are flying into potato fields from nearby weed patches. Existing methods of capturing and marking the dash-sized pests have been difficult and unreliable, according to Unruh, with the ARS Yakima Agricultural Research Laboratory in Wapato, Wash.</p><div style="text-align: justify;"> </div><p style="text-align: justify;">His solution involved mixing egg-white proteins with water to create a solution that can be sprayed onto potato plants or associated weeds like nightshade. Aphids pick up the egg proteins while crawling over treated areas. To track them, Unruh relies on wide-mesh screens secured below a teepee-like scaffold that can be placed in or near potato fields. An adhesive holds the aphids so they can be returned to the laboratory for analysis using an immunological assay, which employs antibodies to detect egg proteins if they're present.</p><div style="text-align: justify;"> </div><p style="text-align: justify;">In fields near Wapato, more than 50 percent of green peach aphids that contacted treated potato plants tested positive for egg proteins. More field tests are under way.</p><div style="text-align: justify;"><br /><br />SOURCE : US Department of Agriculture<br /><br /><br /><br /></div>Unknownnoreply@blogger.com0tag:blogger.com,1999:blog-4205416146202363056.post-83383799950651757762008-08-16T15:12:00.000+07:002008-08-16T15:12:00.337+07:00Climate Change And Species Distributions<div style="text-align: justify;"><br /><br />Scientists have long pointed to physical changes in the Earth and its atmosphere, such as melting polar ice caps, sea level rise and violent storms, as indicators of global climate change.</div><p style="text-align: justify;">But changes in climate can wreak havoc in more subtle ways, such as the loss of habitat for plant and animal species. In a series of talks at the Ecological Society of America (ESA) 93rd Annual Meeting, climate change scientists will discuss how temperature-induced habitat loss can spell disaster for many living things.</p><div style="text-align: justify;"> </div><p style="text-align: justify;">Climate models project that rising temperatures over time can lead to an increase in dry, desert-like conditions, which will affect not only the survivorship of particular species, but also the natural resources they have adapted to use in their natural environment. Species are thus forced to move elsewhere to find places to live and food to eat.</p><div style="text-align: justify;"> </div><p style="text-align: justify;">"Impacts on individual species indicate wider changes at the biome level that will potentially change conditions for many plant and animal species, in addition to ecosystem services to humans," says Patrick Gonzalez, a researcher at The Nature Conservancy and a member of the Intergovernmental Panel on Climate Change (IPCC).</p><div style="text-align: justify;"> </div><p style="text-align: justify;">One species whose habitat may be in danger is the Canada lynx, which is listed as threatened in the United States. The feline's main prey, the snowshoe hare, lives in deep snow cover in boreal forest. Because they rely so heavily on hares for food, lynx are adapted to live in areas with snow cover at least four months out of the year. The cats are so specialized to life on snow that their paws are much wider than is required to support their weight; the large paws help them stalk hares over deep snow without falling in.</p><div style="text-align: justify;"> </div><p style="text-align: justify;">Gonzalez, who has worked with USDA Forest Service scientists to analyze lynx habitat, projects that a temperature increase of 2.5 to 4 degrees Celsius in the coming century across the U.S. and Canada—the range of warming under the scenarios reported by the IPCC—may diminish snow cover suitable for lynx by 10 to 20 percent and reduce boreal forest cover by half in the contiguous U.S. Together, these changes could shift lynx habitat northward and decrease the area of habitat in the lower 48 states by two-thirds. This potentially extensive loss of habitat signals serious changes in boreal and alpine ecosystems, says Gonzalez.</p><div style="text-align: justify;"> </div><p style="text-align: justify;">Climate change can result in animals and plants migrating northward to escape the heat, but in many cases suitable habitat becomes scarce or unavailable farther away from the species' natural range. The Propertius duskywing butterfly lives throughout the West Coast of the U.S., and during its caterpillar stage is specialized to live on oak trees. Shannon Pelini, a graduate student at the University of Notre Dame, conducted experiments revealing that warmer temperatures increased the survivorship and body size of caterpillars in its most northern habitats. A lack of oak trees in more northern climes, however, would preclude them from moving further north. The range shift of oak trees will happen much slower than the shift for the butterflies, leading to a contracted range, says Pelini.</p><div style="text-align: justify;"> </div><p style="text-align: justify;">As if the direct effects of rising temperatures weren't enough, climate change also has impacts that could make climate patterns less consistent over time. Michael Notaro, a scientist at the University of Wisconsin-Madison, used climate data from the past century to model vegetation changes over time. He found that large variability in climate causes an increasing number and intensity of fires and droughts, as well as extreme weather events that could kill long-lived trees and allow short-lived grasses to colonize the leftover space. His models predict that year-to-year variability in precipitation and temperature reduces the Earth's total vegetation cover, expanding its relative grass cover and diminishing its relative tree cover.</p><div style="text-align: justify;"> </div><p style="text-align: justify;">"The central U.S. is characterized by an ecotone that's the intersection of forest in the East and grassland in the West," says Notaro. "The border between these ecosystems is largely determined by climate variability and it is likely that climate change will shift the location of this and other ecological boundaries worldwide."</p><div style="text-align: justify;"> </div><p style="text-align: justify;">Gonzalez agrees that the research results presented at the ESA Annual Meeting indicate serious vulnerabilities of both individual species and global biomes to climate change.</p><div style="text-align: justify;"> </div><p style="text-align: justify;">"Climate change threatens to alter extensive areas of habitat," says Gonzalez. "Lynx is one species that is vulnerable, but the potential impacts of climate change on entire ecosystems are even more alarming."</p><div style="text-align: justify;"> </div><p style="text-align: justify;">The researchers will present their results in the following oral sessions:</p><div style="text-align: justify;"> </div><ol style="text-align: justify;"><li>Shannon Pelini and Patrick Gonzalez - Climate Change: Range and Phenology, Monday, Aug. 4, Midwest Airlines Center</li><li>Michael Notaro - Climate Change and Plants I, Tuesday, Aug. 5, Midwest Airlines Center</li></ol><div style="text-align: justify;"><br /><br />SOURCE : Ecological Society of America<br /><br /><br /></div>Unknownnoreply@blogger.com1tag:blogger.com,1999:blog-4205416146202363056.post-37621644870865287992008-08-16T08:07:00.000+07:002008-08-16T08:07:00.197+07:00Prions Show Their Good Side<div style="text-align: justify;"><br /><br />Prions, the infamous agents behind mad cow disease and its human variation, Creutzfeldt-Jakob Disease, also have a helpful side. According to new findings from Gerald Zamponi and colleagues, normally functioning prions prevent neurons from working themselves to death.</div><p style="text-align: justify;">Diseases such as mad cow result when the prion protein adopts an abnormal conformation. This infectious form creates a template that induces normal copies of the protein to misfold as well. Scientists have long assumed that prions must also have a beneficial side but have been unable to pinpoint any such favorable traits.</p><div style="text-align: justify;"> </div><p style="text-align: justify;">In the new work, the authors found that mice lacking the prion protein had overactive brain cells. Their neurons responded longer and more vigorously to electrical or drug-induced stimulation than did neurons that had normal prion protein. This hyperactivity eventually led to the neurons' death. The results might help explain why misfolded prions cause dementia: in the wrong conformation, the prion can no longer protect brain cells from deadly overexcitement.</p><div style="text-align: justify;"> </div><p style="text-align: justify;">The findings appear in the May 5th issue of the Journal of Cell Biology.</p><div style="text-align: justify;"><br /><br />SOURCE : Rockefeller University<br /><br /><br /></div>Unknownnoreply@blogger.com0tag:blogger.com,1999:blog-4205416146202363056.post-19447694085831946962008-08-15T19:25:00.000+07:002008-08-15T19:25:01.104+07:00In A Bug-eat-bug World, Researchers Use Unique Chinese Wasp To Battle Soybean Aphids<div style="text-align: justify;"><br /><br />The days of soybean aphids feasting on soybean fields may be numbered, thanks to a unique import from China.</div><p style="text-align: justify;">University of Minnesota scientists are field testing a beneficial insect, a stingless wasp from China also known as Binodoxys communis, that kills soybean aphids. A successful field test would be a major breakthrough in controlling a damaging crop pest. The U of M received permission from the federal government to conduct this test and is the leading institution in the testing.</p><p style="text-align: justify;"><br /></p><p style="text-align: justify;"><a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj3aLbMJdnMHhRWfjf0kCmE1sBMJVAPQRUfnMcHCCTKUKIBYuomyBtx5yY_fdX4mgtS5WOruatMjpAMrbZD4T-hiiRiL-E_gc3u8C_n3w3ES5jE0AAc_ONoZDnROATGWfDGm13Iz2FOrlg/s1600-h/070724173347-large.jpg"><img style="margin: 0px auto 10px; display: block; text-align: center; cursor: pointer;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj3aLbMJdnMHhRWfjf0kCmE1sBMJVAPQRUfnMcHCCTKUKIBYuomyBtx5yY_fdX4mgtS5WOruatMjpAMrbZD4T-hiiRiL-E_gc3u8C_n3w3ES5jE0AAc_ONoZDnROATGWfDGm13Iz2FOrlg/s200/070724173347-large.jpg" alt="" id="BLOGGER_PHOTO_ID_5233613547705446546" border="0" /></a></p><div style="text-align: justify;"> </div><p style="text-align: center;"><span style="font-size:85%;"><em>Researchers look for mummies, the darker brown objects on the soybean leaf shown above,<br />to gauge the effectiveness of the beneficial insect in controlling soybean aphids.<br />The light green spots on the soybean leaf are soybean aphids.<br />(Credit: David Hansen, Minnesota Agricultural Experiment Station)</em></span></p><p style="text-align: justify;"><br /></p><p style="text-align: justify;">The soybean aphid first appeared in Minnesota fields in 2000 and today costs soybean growers an estimated $200 million annually in lost crop yields and spraying costs in Minnesota alone. The national cost is much higher. </p><div style="text-align: justify;"> </div><p style="text-align: justify;">"The soybean aphid was imported without any of its natural enemies, the organisms that keeps aphids in check in China," said Dave Ragsdale, U of M entomologist. "Our researchers and Extension experts are working to provide that check and balance system."</p><div style="text-align: justify;"> </div><p style="text-align: justify;">Multiple stages of evaluation and testing have been completed at the Insect Quarantine Facility, a joint effort between the Minnesota Department of Agriculture and the Minnesota Agricultural Experiment Station on the U of M's St. Paul Campus. Special security and air filtration systems ensure the insects being evaluated don't venture out on their own. Field testing will take place in a limited number of grower fields and at Research and Outreach Centers.</p><div style="text-align: justify;"> </div><p style="text-align: justify;"> Binodoxys communis was approved for release based upon four years of laboratory safety testing. It is an especially promising species for control of soybean aphid, because it comes from a region in China that is a good climate match to Minnesota. The stingless wasp specializes in soybean aphid and has been observed apparently controlling it in China.</p><div style="text-align: justify;"> </div><p style="text-align: justify;">A cooperative effort between the U of M, the state and soybean growers, like New Richland farmer Larry Muff, have made this experiment possible.</p><div style="text-align: justify;"> </div><p style="text-align: justify;">"The soybean check off is committed to supporting research that will mitigate this devastating pest," said Muff, co-chair of the Minnesota Soybean Research and Tech Transfer Committee. "Organic growers will also benefit from this biological control of aphids." </p><div style="text-align: justify;"> </div><p style="text-align: justify;">University researchers and Minnesota Department of Agriculture scientists will monitor the ability of Binodoxys communis to kill soybean aphids this summer and continue the attack this fall when soybean aphids move to buckthorn plants and survive the winter to battle soybean aphids in 2008. </p><div style="text-align: justify;"> </div><p style="text-align: justify;">The researchers also have a backup plan. Eleven other species and strains of stingless wasps are under evaluation and some of these that have shown promise from both a safety and efficacy standpoint may be field tested in 2008.</p><div style="text-align: justify;"><br /><br />SOURCE : University of Minnesota<br /><br /><br /></div>Unknownnoreply@blogger.com0tag:blogger.com,1999:blog-4205416146202363056.post-74825220537694280252008-08-15T19:01:00.000+07:002008-08-15T19:01:00.400+07:00Selection On Sex Cells Favors A Recombination Gender Gap<div style="text-align: justify;"><br /><br />Males and females of the same species can be strikingly different. Peacocks strut around with flashy feathers to attract mates, while peahens blend into their surroundings with more subdued colors. But differences are not always as obvious or easily explainable as in this classic example. Even the amount of genetic reshuffling that goes on during egg and sperm production differs between males and females in most species. An evolutionary reason for this has eluded researchers since the phenomenon was originally discovered in fruitflies, Chinese silk worms, and amphipods almost 100 years ago.<br /><br />Genetic diversity among organisms is promoted when genetic information is rearranged during meiosis, the cell division process that yields sperm and eggs (generically called gametes). During this genetic reshuffling, chromosome pairs overlap, forming structures called chiasmata (“crosses” in Greek), and physically recombine. This process does not just create diversity, it is also an example of diversity—recombination rates vary across chromosomes, sexes, and species.<br /><br />An early 20th century hypothesis to explain the sex difference in recombination proposed that recombination is restrained within a pair of unlike sex chromosomes (X and Y, for example) and that the suppression spills over to the rest of the chromosomes. Under this idea, the sex with dissimilar sex chromosomes (XY instead of XX, for example) should be the one with the least amount of recombination in all chromosomes. But that is not always the case. Some hermaphroditic species of flatworms, for example, lack sex chromosomes altogether but still display marked differences in male and female recombination rates. In one salamander genus, more reshuffling unexpectedly occurs in the sex with two different sex chromosomes.<br /><br />In a new study analyzing an updated dataset of 107 plants and animals, Thomas Lenormand and Julien Dutheil bolster the argument against the recombination suppression hypothesis by showing that in species with sex chromosomes, the sex with two dissimilar sex chromosomes doesn’t necessarily have a reduced recombination rate. Additionally, they found that, as a trait, the sex difference in recombination rate is not a lot more similar between two species in the same genus than between two species in different genera, suggesting that the difference evolves quickly.<br /><br />An alternative hypothesis suggests that sexual selection might play a role in recombination differences. Reproductive success among males is often highly influenced by selection, so mixing up successful genetic combinations in males could be evolutionarily counterproductive. But in past studies, sexual selection was not related to variation in recombination rates.<br /><br />Putting a new twist on this hypothesis, Lenormand and Dutheil realized that selection was not necessarily limited to the adult stage and that differences in selection among eggs or sperm might help account for recombination differences between the sexes. The authors reasoned that more opportunity for selection on sperm than egg should correspond to less recombination during sperm than egg production (and vice versa), consistent with the idea that genetic combinations surviving selection should remain more intact in the sex experiencing the strongest selection at the gametic stage.<br /><br />Though male gametes might be expected to be under stronger selection in many species, in true pines it seems to be the female gametes. The ovules compete with each other for resources over an entire year before being fertilized, and, indeed, from the dataset analysis, ovule production involves low recombination rates compared with male pollen in this group. In males, the opportunity for pollen competition was indirectly estimated using self-fertilization rates. The authors assumed that pollen grains competing for ovules of a self-fertilizing plant would be genetically similar and therefore experience less selection. Again, in the analysis, low selection correlated with less recombination in female gamete production, as predicted.<br /><br />Is selection among eggs and sperm the evolutionary force generating sex-based variation in genetic shuffling? By demonstrating that differences may be influenced by gamete selection in plants, this work has added clarity to otherwise contradictory observations.<br /><br /><br />SOURCE : Public Library Of Science<br /><br /><br /><br /></div>Unknownnoreply@blogger.com0tag:blogger.com,1999:blog-4205416146202363056.post-34711161037530745292008-08-15T07:09:00.000+07:002008-08-15T07:09:00.269+07:00In Bowerbirds, Young Females Go More For Blue, Less For Strutting<div style="text-align: justify;"><br /><br />ARLINGTON, Va.- When looking for sex partners, younger females prefer males who decorate their place with a little extra blue, be it plastic or feathers. They also prefer males who tone down the intensity of their courtship behavior. At least, that's how it looks for satin bowerbirds, according to research findings published this week in the journal Nature.<br /></div><p style="text-align: justify;"> The study - conducted in New South Wales, Australia, in 1999-2000 - found that not all females find the same traits attractive in mates. As they choose a mate, females make a series of complex decisions related to male courtship behavior and to the colored decorations males collect and place around the bower, a stick structure that protects females during courtship display. Older females focus more on the male's intense courtship display while younger females are attracted by the blue bower decorations. </p><div style="text-align: justify;"> </div><p style="text-align: justify;">The research, funded by the National Science Foundation's Animal Behavior Program, was conducted by biologists Gerald Borgia, Seth Coleman and Gail Patricelli of the University of Maryland. NSF is an independent U.S. federal agency that supports fundamental research and education across all fields of science and engineering.</p><div style="text-align: justify;"> </div><p style="text-align: justify;">According to Borgia, learning more about such sophisticated courtship behavior can increase our understanding of mate choice, a fundamental process that affects the genetics of most animal species. Thus, clues to courtship can also aid wildlife conservation and species propagation.</p><div style="text-align: justify;"> </div><p style="text-align: justify;">"It's very important," he said, "because it helps us develop a general model of mate choice. We show experimentally that females in a population may choose males for different reasons. This, in turn, explains why males have complex displays - that is to accommodate the different mating preferences of females they engage in courtship."</p><div style="text-align: justify;"> </div><p style="text-align: justify;">A male bowerbird's intense performance of "Pick me! Pick me!" involves loud buzzing calls, raising its feathers on end, and running vigorously back and forth, with its wings extended, across its platform stage - the bower. Males build their bowers primarily from sticks, creating a U-shaped chute that they adorn with blue decorations, such as feathers, blue clothespins, and scraps of plastic.</p><div style="text-align: justify;"> </div><p style="text-align: justify;">To see if bluer-is-better interior decorating affects females' preferences, the researchers supplemented some bowers with blue plastic tiles and strands. Because male bowerbirds commonly steal from each other, researchers anchored these extra accoutrements with screws and glue.</p><div style="text-align: justify;"> </div><p style="text-align: justify;">According to Jane Brockmann of NSF's animal behavior program, "This is an excellent system for studying mate choice. Dr. Borgia watches the bowers by using video cameras that are tripped when a female enters a male's bower, so he has a very accurate record of whether a female just visits a male or mates with him. He has also been studying the same large group of marked birds for years, so he knows when a female's choice changes with age and experience."</p><div style="text-align: justify;"> </div><p style="text-align: justify;">Very few studies have this sort of long-term data, and most studies of mate choice treat females as if their decisions do not vary or change, said Brockmann. </p><div style="text-align: justify;"> </div><p style="text-align: justify;">"Males of most species show a lot of variation in their behavior," she said. "It is unreasonable to think that females would not similarly show variation. Yet we know very little about variation in how females choose mates. It does matter." </p><div style="text-align: justify;"> </div><p style="text-align: justify;">Particularly to males. </p><div style="text-align: justify;"> </div><p style="text-align: justify;">Michael Greenfield, who co-directs NSF's animal behavior program with Brockmann, said, "As males are under some pressure to be attractive to and mate with as many females as possible, their display is a means of covering all possibilities in luring potential mates. We still don't really know why female preference varies with age, but one possibility inherent in this study is that learning - which is generally disregarded in studies of sexual selection - plays a role." </p><div style="text-align: justify;"> </div><p style="text-align: justify;">As scientists learn more about how females choose mates, biologists will be better able to test various models of how courtship displays evolve among males, Borgia said. </p><div style="text-align: justify;"> </div><p style="text-align: justify;">In a previous study, his group found that female satin bowerbirds will return the next year to attractive mates, but "females which fail to encounter very attractive males typically reject their previous mates and search for more attractive males in the following year."</p><div style="text-align: justify;"><br /><br />SOURCE : National Science Foundation<br /><br /><br /></div>Unknownnoreply@blogger.com0tag:blogger.com,1999:blog-4205416146202363056.post-28687164966175720122008-08-14T18:52:00.000+07:002008-08-14T18:52:01.276+07:00Behavioural Ecologists Elucidated How Peahens Choose Their Mates, And Why<div style="text-align: justify;"><br /><br />Since Darwin, the peacock exhibiting an elongated tail composed of ocelli has been considered a prime example of the strength of sexual selection. Professor Marion Petrie's classical studies have shown that females prefer males with a high number of ocelli. However, a remaining question concerning the role played by ocelli is how peahens value their number. New research published today in Ethology describes that females may actually assess ocelli density.<a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiV9wafK7j85vw6IYZt8KlfWV1MwnYT3klwY4BxjQtKTdo8Q3_iVcDoNOdD-EqEKlTYIru0BxCajF60blsuJK6JfPIUppYb2d-44CfvnnQGK7D_YXF6vCobJwcmstFCxZxH4t89wEs8Z9A/s1600-h/050814172316.jpg"><img style="margin: 0px auto 10px; display: block; text-align: center; cursor: pointer;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiV9wafK7j85vw6IYZt8KlfWV1MwnYT3klwY4BxjQtKTdo8Q3_iVcDoNOdD-EqEKlTYIru0BxCajF60blsuJK6JfPIUppYb2d-44CfvnnQGK7D_YXF6vCobJwcmstFCxZxH4t89wEs8Z9A/s320/050814172316.jpg" alt="" id="BLOGGER_PHOTO_ID_5233599448187360290" border="0" /></a></div><p style="text-align: center;"><span style="font-size:85%;"><em>Since Darwin, the peacock exhibiting an elongated tail<br />composed of ocelli has been considered a prime example of the strength of sexual selection.<br />Professor Marion Petrie's classical studies have shown that females prefer males<br />with a high number of ocelli. (Image courtesy of Blackwell Publishing Ltd.)</em></span></p><p style="text-align: center;"><span style="font-size:85%;"><em><br /></em></span></p><p style="text-align: justify;">Adeline Loyau, Michel Saint Jalme and Gabriele Sorci of the National Museum of Natural History and the Laboratory of Evolutive Parasitology, Paris, have been studying sexual selection on free-ranging common peafowl to elucidate how females choose their mate. They took pictures of displaying peacocks to count the number of ocelli, and captured them to measure tail length. They also made behavioural observations to value male displaying activity and male mating success.</p><div style="text-align: justify;"> </div><p style="text-align: justify;">"Preferred males were those exhibiting the higher number of ocelli in the train, but surprisingly females seemed to prefer males with shorter tails. This was unpredictable because we also found that the longer the train, the more dominant the male," they say. The female preference for both high number of ocelli and shorter tail gave the idea that females may actually prefer the visual perception of a dense cluster of ocelli than a diluted number of ocelli over a large surface. "We calculated the ocelli density and found that it did explain female choice."</p><div style="text-align: justify;"> </div><p style="text-align: justify;">In the peacock, the ocelli density of the train can only be assessed by females when males spread their trains during the courtship display. "In this species, the expression of the ornament is modulated by the expression of the behaviour. To be chosen, a peacock has to be beautiful but also has to be able to show how beautiful he is. It is not surprising that female preference is also driven by male behaviour." Indeed, they showed that male success was determined by both his ocelli density and his displaying activity. They investigated this preference further and demonstrated that these two cues provide peahens with information about male health. "In other words, it's beneficial for a female to mate with handsome and sportive mates," they conclude with humour, "because these males are in better health."</p><div style="text-align: justify;"><br /><br />SOURCE : Blackwell Publishing Ltd.<br /><br /><br /><br /></div>Unknownnoreply@blogger.com0tag:blogger.com,1999:blog-4205416146202363056.post-24477081358233756892008-08-14T14:28:00.001+07:002008-08-14T14:28:00.802+07:00Researchers Find Resistance To Soybean Fungus<div style="text-align: justify;"><br /><br />The first soybean line with genetic resistance to charcoal rot has been released by Agricultural Research Service scientists in Mississippi.<br /><br /><br /><a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEidxAH0VoE8vGnz5SRvSBBnuN_V5jq7fX4xyY_yUo8wQorqeR6MvgVVjHWXnrEOT3hIIjILiIG9aKSkBey_Ic0W885stG8c0qbij0j1DQFWalCkdLKHXGADupPn8icb1FFqYyepXJVez_U/s1600-h/050619192818.jpg"><img style="margin: 0px auto 10px; display: block; text-align: center; cursor: pointer;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEidxAH0VoE8vGnz5SRvSBBnuN_V5jq7fX4xyY_yUo8wQorqeR6MvgVVjHWXnrEOT3hIIjILiIG9aKSkBey_Ic0W885stG8c0qbij0j1DQFWalCkdLKHXGADupPn8icb1FFqYyepXJVez_U/s320/050619192818.jpg" alt="" id="BLOGGER_PHOTO_ID_5233623603899675842" border="0" /></a><br /></div><p style="text-align: justify;">Charcoal rot, caused by the soilborne fungus Macrophomina phaseolina, is a major yield-limiting disease of the Mid-South and other soybean-producing regions throughout the world.</p><div style="text-align: justify;"> </div><p style="text-align: justify;">The new line, DT97-4290, developed by scientists in the ARS Crop Genetics and Production Research Unit at Stoneville, is a potentially valuable source of resistance to charcoal rot for soybean breeders and producers in areas experiencing yield losses due to the disease.</p><div style="text-align: justify;"> </div><p style="text-align: justify;">Charcoal rot symptoms usually appear when weather conditions are hot and dry, causing the soybean plant to lose vigor. In more advanced stages, petioles and leaves may turn yellow and wilt, while remaining attached to the plant. No chemical controls currently exist for charcoal rot, and resistance has been hard to identify.</p><div style="text-align: justify;"> </div><p style="text-align: justify;">Field studies were conducted at Stoneville to find charcoal rot resistance among 24 selected soybean genotypes. The researchers identified three breeding lines with genetic resistance, according to Bob Paris, the research geneticist who developed the line with Alemu Mengistu, a soybean pathologist.</p><div style="text-align: justify;"> </div><p style="text-align: justify;">The new line was selected for its adaptation to the clay soils of the lower Mississippi River valley, and for its field resistance to charcoal rot, soybean mosaic virus and stem canker, and moderate resistance to frogeye leafspot.</p><div style="text-align: justify;"> </div><p style="text-align: justify;">Genetic material of this release will be deposited in the National Plant Germplasm System, where it will be available for soybean researchers and breeders.</p><div style="text-align: justify;"> </div><p style="text-align: justify;">ARS is the U.S. Department of Agriculture's chief scientific research agency.</p><div style="text-align: justify;"><br /><br />SOURCE : USDA / Agricultural Research Service<br /><br /><br /></div>Unknownnoreply@blogger.com0tag:blogger.com,1999:blog-4205416146202363056.post-81516962484928014912008-08-14T08:03:00.000+07:002008-08-14T08:03:00.828+07:00Nano-sensor For Better Detection Of Mad Cow Disease Agent<div style="text-align: justify;"><br /><br />In an advance in food safety, researchers in New York are reporting development of a nano-sized sensor that detects record low levels of the deadly prion proteins that cause Mad Cow Disease and other so-called prion diseases.<br /><br /><br /><a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiWvDKc6yOBPprjlTOymp1zNcdzM0yYCwNBmXfdQUyv5mTm2l60-UnJpd9RFkUDNCYmWDMQ2HCG0JtlMDpW2L9_0fmDYga2kn-yroO9lmbEG4ZQm7HF3f3kCNuiinmjT_rQ2QP2vsbHbns/s1600-h/080303093549-large.jpg"><img style="margin: 0px auto 10px; display: block; text-align: center; cursor: pointer; width: 142px; height: 212px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiWvDKc6yOBPprjlTOymp1zNcdzM0yYCwNBmXfdQUyv5mTm2l60-UnJpd9RFkUDNCYmWDMQ2HCG0JtlMDpW2L9_0fmDYga2kn-yroO9lmbEG4ZQm7HF3f3kCNuiinmjT_rQ2QP2vsbHbns/s200/080303093549-large.jpg" alt="" id="BLOGGER_PHOTO_ID_5233616440435023394" border="0" /></a></div><p style="text-align: center;"><span style="font-size:85%;"><em>Scientists report a new device to detect prion proteins<br />that cause Mad Cow Disease and other prion diseases.<br />The finding could lead to a reliable blood test for those illnesses in both animals and humans.<br />(Credit: Courtesy of USDA-Agricultural Research Service, Photo by Keith Weller)</em></span></p><p style="text-align: justify;"><br /></p><p style="text-align: justify;">The sensor, which detects binding of prion proteins by detecting frequency changes of a micromechanical oscillator, could lead to a reliable blood test for prion diseases in both animals and humans, the researchers say.</p><div style="text-align: justify;"> </div><p style="text-align: justify;">Prions are infectious proteins that can cause deadly nerve-damaging diseases such as Mad Cow Disease in cattle, scrapie in sheep, and a human form of Mad Cow Disease called variant Creutzfeldt-Jakob Disease. Conventional tests are designed to detect the proteins only upon autopsy and the tests are time-consuming and unreliable.</p><div style="text-align: justify;"> </div><p style="text-align: justify;">In the new study, Harold G. Craighead and colleagues describe a high-tech, nano-sized device called a nanomechanical resonator array. The device includes a silicon sensor, which resembles a tiny tuning fork, that changes vibrational resonant frequency when prions bind. Its vibration patterns are then measured by a special detector. In experimental trials, the sensor detected prions at concentrations as low as 2 nanograms per milliliter, the smallest levels measured to date, the researchers say.</p><div style="text-align: justify;"> </div><p style="text-align: justify;">The article "Prion Protein Detection Using Nanomechanical Resonator Arrays and Secondary Mass Labeling" is scheduled for the April 1 issue of ACS' Analytical Chemistry.<br /></p><div style="text-align: justify;"><br /><br />SOURCE : American Chemical Society<br /><br /><br /></div>Unknownnoreply@blogger.com0tag:blogger.com,1999:blog-4205416146202363056.post-12628861772144961402008-08-13T18:37:00.000+07:002008-08-13T18:37:00.879+07:00Changing Fashions Govern Mating Success In Lark Buntings, Study Finds<div style="text-align: justify;"><br /><br />A study of how female lark buntings choose their mates, published in Science, adds a surprising new twist to the evolutionary theory of sexual selection. Researchers at the University of California, Santa Cruz, discovered that female lark buntings show strong preferences for certain traits in the males, but those preferences change from year to year.</div><br /><p style="text-align: justify;">Classic examples of sexual selection involve elaborate ornaments, such as the peacock's tail, that evolve as a result of consistent female preferences, so that males with the most exaggerated traits have the most success mating and produce more offspring than less flamboyant competitors. In the case of lark buntings, however, the flexibility shown by females in choosing their mates dampens the trend toward more elaborate ornamentation and may instead maintain variability in male plumage.</p><p style="text-align: justify;"><br /></p><p style="text-align: justify;"><a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg6mTRYlqIBvA3mQ2-R0gzYdPQzEia31pgppbgB-Y6qzZr8tv6bFbzfM5gLb7mb3NdkIDaJBa_Brb2MbifFnY14jNX_fuu4NcabZr23COf01XMQAQNHNRWCoc-FWZPwZd7cJ9Zy76ix3vo/s1600-h/080124145026.jpg"><img style="margin: 0px auto 10px; display: block; text-align: center; cursor: pointer;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg6mTRYlqIBvA3mQ2-R0gzYdPQzEia31pgppbgB-Y6qzZr8tv6bFbzfM5gLb7mb3NdkIDaJBa_Brb2MbifFnY14jNX_fuu4NcabZr23COf01XMQAQNHNRWCoc-FWZPwZd7cJ9Zy76ix3vo/s320/080124145026.jpg" alt="" id="BLOGGER_PHOTO_ID_5233594593904445394" border="0" /></a></p><br /><div style="text-align: justify;"> </div><p style="text-align: justify;">"It's counter to the conventional view of female choice as static," said Bruce Lyon, associate professor of ecology and evolutionary biology at UCSC and coauthor of the paper. "These females are capable of very sophisticated behavior, and they appear to benefit from their flexibility in mate choice by gaining enhanced nesting success."</p><div style="text-align: justify;"> </div><p style="text-align: justify;">The study suggests that the male's plumage somehow serves as a signal to the female that he possesses certain traits that will affect the pair's nesting success. Shifting environmental conditions may determine which male traits matter most in any given year, said Alexis Chaine, who worked on the study as a UCSC graduate student and is now a postdoctoral researcher at the Centre National de la Recherche Scientifique (National Center for Scientific Research) in France. Chaine is first author of the paper, which appears in the January 25 issue of Science.</p><div style="text-align: justify;"> </div><p style="text-align: justify;">"The traits the female is choosing somehow predict how successful the pair will be in nesting," Chaine said. "One possibility is that certain traits are associated with the male being a good forager, and other traits predict how well he could defend the nest from predators. So, if there are lots of ground squirrels, which are a major nest predator, she wants a good defender, but in a year when grasshopper populations are low, she needs a good provider. These are ideas we still need to test."</p><div style="text-align: justify;"> </div><p style="text-align: justify;">With a mostly black body and bright white wing patches, the male lark bunting is a distinctive bird of the Great Plains. Females choose a new mate every year, and parenting duties are shared by both members of the pair. The males are territorial during the breeding season, flying up over their territory and singing as they descend to attract a mate. Once they acquire a mate, however, they no longer defend the territory. The researchers found no correlation between the quality of a male's territory and his success in attracting a mate.</p><div style="text-align: justify;"> </div><p style="text-align: justify;">The white wing patches and other male plumage traits serve as signals in aggressive interactions between territorial males, Chaine said, meaning that female mate choice is not the only factor influencing those traits. But the researchers found that the role of those signals in competitive interactions between males was consistent from year to year. The level of aggression didn't vary between years either.</p><div style="text-align: justify;"> </div><p style="text-align: justify;">"Male competition can't explain the overall pattern, but it may be an important factor in the evolution of male plumage traits," Chaine said.</p><div style="text-align: justify;"> </div><p style="text-align: justify;">The variability of the male plumage was one of the first things Lyon noticed when he began studying lark buntings on the Pawnee National Grasslands in Colorado. (The lark bunting is the state bird of Colorado.) Chaine joined Lyon the following year and began an exhaustive long-term study, gathering data from 1999 to 2003.</p><div style="text-align: justify;"> </div><p style="text-align: justify;">"We had to conduct studies every year over several years before we could see what was going on," Lyon said. "We saw two patterns of variation in the correlations between male traits and female mate choice. In some cases, it was either on or off--a trait was important to females one year and not important in other years. We also saw reversals--for example, one year the females preferred males with bigger wing patches, and the next year they preferred smaller wing patches."</p><div style="text-align: justify;"> </div><p style="text-align: justify;">Lyon cautioned that additional experiments are needed to provide definitive evidence of female preferences. The study was based on statistical correlations, which provide clear evidence that the traits of mated males differ from those of males without mates. "We suspect it's because females are choosing males with particular traits," Lyon said. "Ideally, we would like to test that with field experiments."</p><div style="text-align: justify;"> </div><p style="text-align: justify;">The dynamic sexual selection seen in lark buntings is probably occurring in other species as well, he added. That has implications for theoretical models of how sexual selection influences the evolution of male traits.</p><div style="text-align: justify;"> </div><p style="text-align: justify;">"The assumption that sexual selection is static is something we've all taken for granted," Chaine said. "This study might cause some people to rethink their systems and take another look at their data."</p><div style="text-align: justify;"> </div><p style="text-align: justify;">This research was supported by grants from the National Geographic Society, National Science Foundation, American Museum of Natural History, Sigma Xi, and the American Ornithologist's Union.</p><div style="text-align: justify;"><br />SOURCE : University of California - Santa Cruz<br /><br /><br /><br /></div>Unknownnoreply@blogger.com0tag:blogger.com,1999:blog-4205416146202363056.post-68574958284974305982008-08-13T13:49:00.000+07:002008-08-13T13:49:01.130+07:00Test To Protect Food Chain From Human Form Of Mad Cow Disease<div style="text-align: justify;"><br /><br />Scientists are reporting development of the first test for instantly detecting beef that has been contaminated with tissue from a cow's brain or spinal cord during slaughter — an advance in protecting against possible spread of the human form of Mad Cow Disease. </div><p style="text-align: justify;">Jürgen A. Richt and colleagues point out that removal of brain, spinal and other central nervous tissue after slaughter is "one of the highest priority tasks to avoid contamination of the human food chain with bovine spongiform encephalopathy," better known as Mad Cow Disease. "No currently available method enables the real-time detection of possible central nervous system (CNS) tissue contamination on carcasses during slaughter," the report states.</p><div style="text-align: justify;"> </div><p style="text-align: justify;">They describe a test based on detection of the fluorescent pigment lipofuscin, a substance that appears in high concentrations in the nervous tissue of cattle. The researchers found that it was a dependable indicator for the presence of brain and spinal tissue in bovine carcasses and meat cuts. </p><div style="text-align: justify;"> </div><p style="text-align: justify;">"Small quantities of bovine spinal cord were reliably detected in the presence of raw bovine skeletal muscle, fat and vertebrae. The research lays the foundation for development of a prototype device allowing real-time monitoring of CNS tissue contamination on bovine carcasses and meat cuts," the report says.</p><div style="text-align: justify;"> </div><p style="text-align: justify;">It was done with colleagues from the National Animal Disease Center of the USDA-Agricultural Research Service and Iowa State University.</p><div style="text-align: justify;"><br /><br />SOURCE : American Chemical Society<br /><br /><br /></div>Unknownnoreply@blogger.com0