Monday, January 5, 2009

New Breeding Ground For Endangered Whales? High Numbers Of Right Whales Seen In Gulf Of Maine

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.

Three North Atlantic right whales are visible at the surface on Jordans Basin.
A fourth whale is visible just below the surface at lower left. (Credit: NOAA/Misty Niemeyer)

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.

“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.”

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.

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.

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.

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.

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.

SOURCE : National Oceanic And Atmospheric Administration

Hot Southern Summer Threatens Coral With Massive Bleaching Event

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.

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.
(Credit: iStockphoto/Tammy Peluso)

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.

“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.

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.

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.

“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.

“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.“

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.

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.

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.

SOURCE : World Wildlife Fund

Saturday, January 3, 2009

Structure Of New Botulism Nerve Toxin Subtype Revealed

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)

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.

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.

“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.

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.

“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.”

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.

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.

“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.
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.

“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.

This finding may help scientists develop faster-acting vaccines and therapeutic agents.
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.

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.

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.”

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.

SOURCE : DOE/Brookhaven National Laboratory

Grape-seed Extract Kills Laboratory Leukemia Cells, Proving Value Of Natural Compounds

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.
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.
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.
"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.
"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.
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."
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.
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.
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.
They also discovered that the extract does not affect normal cells, although they don't know why.
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.
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.
"This is a natural compound that appears to have relatively important properties," Shi said.
SOURCE : American Association for Cancer Research

Four Years After Tsunami, Coral Reefs Recovering

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.

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.

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.

“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.”

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.

Since then, some communities have moved away from destructive fishing and have even begun transplanting corals to recover damaged areas.

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.

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.

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.

“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.”

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.

SOURCE : Wildlife Conservation Society.

Wednesday, August 20, 2008

In Promiscuous Antelopes, The 'Battle Of The Sexes' Gets Flipped

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.

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.

Mother nursing baby topi antelope in Serengeti National Park in Tanzania,
East Africa. (Credit: iStockphoto/Bruce Block)

"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."

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."

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.

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.

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."

This research was published online on November 29th in Current Biology.

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.

SOURCE : Cell Press