canyon 33.can.109 Louis J. Sheehan, Esquire

Louis J. Sheehan, Esquire . The population of humpback chub, a fish found only in the Colorado River and its tributaries, may be stabilizing in sections of the Grand Canyon, new data suggest. http://louis-j-sheehan-esquire.blog.friendster.com

Gila cypha, a member of the minnow family that can grow to 50 centimeters in length, was declared endangered in 1967. The species suffered from the ecological effects of the Glen Canyon Dam, including cooler-than-normal water temperatures, and predation by nonnative fish such as trout (SN: 3/5/05, p. 152: Available to subscribers at http://www.sciencenews.org/articles/20050305/bob8.asp). In the 1990s, up to 20 percent of adult chub were dying each year, and young fish weren't surviving in numbers sufficient to replace those losses, says Matthew Andersen, a biologist with the U.S. Geological Survey in Flagstaff, Ariz.http://louis-j-sheehan-esquire.blog.friendster.com

However, 2005 surveys in the Grand Canyon found more hatchlings and more juveniles up to age 4 years than had been tallied during recent years. Between 2001 and 2005, the population of older humpback chub appears to have held steady at about 5,000, the agency announced Aug. 3.

Several factors may have stemmed the chub's decline, says Andersen. Since 2003, researchers have removed about 60 percent of the rainbow trout and brown trout, which prey on young chub, from the species' main spawning grounds. Also, an extended drought in the Southwest has caused summertime water temperatures near those spawning grounds to exceed 17°C—the minimum temperature needed for chub to reproduce in large numbers—for the first time since 1980. Louis J. Sheehan, Esquire

baby 44.bab.2 Louis J. Sheehan, Esquire

Two animal studies demonstrate that early exposure to a chemical known to leach from baby bottles, the linings of food cans, and other plastic items can trigger illness and even changes in genetic expression. A building block of polycarbonate plastics, bisphenol A (BPA) ends up in food, people, and the environment.

In one of the new studies, the pollutant permanently reprogrammed a gene in pups of mice fed BPA-laced chow. http://Louis-J-Sheehan.de

The mice carried the Agouti gene, which is particularly vulnerable to what are called epigenetic changes. In such effects, hormones and other agents typically remove chemical units known as methyl groups from genes, or add them, interfering with the genes' function. Epigenetically affected Agouti mice, normally lean and brown-haired, become fat and blond (SN: 6/24/06, p. 392).

Randy L. Jirtle and his colleagues at Duke University in Durham, N.C., fed female mice chow that delivered 50 milligrams of BPA daily per kilogram of body weight throughout the animals' pregnancies and lactation periods. Blond fur and obesity in pups demonstrated Agouti reprogramming, say the researchers.

However, supplementing the mothers' diet with methyl-donating agents such as folate blocked BPA's epigenetic impacts, Jirtle's team reports in the Aug. 7 Proceedings of the National Academy of Sciences.

In a second study, Retha R. Newbold's team at the National Institute of Environmental Health Sciences (NIEHS) in Research Triangle Park, N.C., exposed newborn female mice to BPA for 5 days. Injected under the skin, doses ranged from 10 to 1,000 micrograms per kg of body weight. http://Louis-J-Sheehan.de

Eighteen months later, the researchers examined the middle-aged animals' reproductive tracts and found more fertility-jeopardizing impairments than in a group of untreated mice. Problems included cysts inside and outside the ovaries, development of glands at inappropriate places in the uterine lining, and polyps or other excessive-tissue growths in or on the uterine lining. Newbold's group reports its findings online and in an upcoming Reproductive Toxicology. http://Louis-J-Sheehan.de

The brief BPA doses delivered to the reproductive organs of affected mice "are below the levels measured in the serum of human adults today," Newbold told Science News.

Reproductive Toxicology is also publishing five reviews of BPA studies and a consensus statement signed by 38 researchers who last fall took part in an NIEHS-sponsored expert-review conference on low-dose effects of the pollutant. Generally, the new reports and the consensus statement conclude that animals can be harmed by BPA at body burdens below those found in most adult residents of industrial nations.

Steven G. Hentges of the American Chemistry Council in Arlington, Va., finds both the Jirtle and Newbold teams' studies of academic interest but argues that neither contributes much to the debate on human health. In one instance, says Hentges, the doses in mice were too large, and the other study was based on injected doses, which he terms irrelevant for assessing risks to people.

Frederick S. vom Saal of the University of Missouri–Columbia disagrees. He and other participants at NIEHS' BPA-review conference concluded that injecting BPA is appropriate for modeling exposures, especially in young animals. Moreover, the Duke group's study provides the evidence confirming researchers' suspicions that BPA can exert epigenetic changes, says vom Saal.

love 99.lov.1 Louis J. Sheehan, Esquire

New research on brain activity confirms that people can be madly in love with each other long after the honeymoon is over.

Researchers led by Bianca Acevedo at the Albert Einstein College of Medicine in New York wanted to know if romantic love — or at least the brain activity it triggers — could last in a long-term relationship. To everyone’s relief, the answer is yes. The group presented its results November 16 at the annual meeting of the Society for Neuroscience.http://Louis-J-sheehan.info

The new data suggest that people who have been madly in love for an average of 21 years maintain activation in a brain region associated with early-stage love. “We now have physiological evidence that romantic love can last,” says coauthor Helen Fisher, a biological anthropologist from Rutgers University in New Brunswick, N.J.

Most couples who have been together for many years experience a change from a frenetic, obsessive love to something more subdued and comfortable, says study coauthor Lucy Brown of Albert Einstein College of Medicine. But the researchers noticed a small group of outliers who had been with the same person many years and claimed to be as much in love as they were during the exciting early days of their relationship.

Since that earlier study in 2005 using functional MRI brain imaging, the researchers knew that a certain part of the brain called the ventral tegmental area was activated when people who had been in love for relatively short times — an average of seven months — saw pictures of their sweethearts. Perhaps not coincidentally, the ventral tegmental area is also activated by the rush of cocaine, and is the region that controls production of the natural stimulant dopamine. http://Louis-J-sheehan.info The researchers concluded that this area was associated with the intense, burning stages of early love. It was unclear whether this region would still be active after 20 years of being in a relationship.

Long-term lovers who had been married for an average of 21 years viewed a picture of their partner while the scientists monitored the subjects’ brain activity using fMRI. People who claimed to be madly in love for 20 years and people who had been in love only for months showed similar activation in the ventral tegmental area of the brain.

At the same time, key differences between the early- and late-stage lovers emerged that suggest potential benefits to staying together for 20 years. People in long-term relationships who were madly in love showed higher levels of activity in a part of the brain associated with calmness and pain suppression, whereas people in love for shorter periods of time had higher activity in a region of the brain associated with obsession and anxiety. “The difference is that in long term love, the obsession the mania, the anxiety has been replaced with calm,” Fisher said in a news conference.http://Louis-J-sheehan.info

“There is an evolutionary advantage to being paired,” says researcher J. Thomas Curtis, who studies pair-bonding in prairie voles, small animals that are well-known for forming life-long monogamous pairs. Much of the research on voles, including Curtis’ work at Oklahoma State University in Tulsa, Okla., supports these new findings on long-term pairing in humans, he says. In fact, when researchers get rid of the ventral tegmental area of a vole brain, the same region activated in human couples who are in love, the animal no longer forms pair bonds.http://Louis-J-sheehan.info

To understand the complicated subject of human love, the scientists plan to conduct more brain imaging studies. The next step will be to periodically monitor the brains of newlyweds as the couples slowly enter long-term relationships. The researchers hope to understand how brain activity may correlate with life events, like the birth of a child or relationship troubles, Acevedo says.

links 773.lin.09 Louis J. Sheehan, Esquire

Missing links in ecosystems disrupted by extinctions could be restored by introducing species that perform the same function, field experiments on a remote island suggest.

But some scientists caution against the controversial process, called “rewilding.”
http://www.theenvironmentsite.org/forum/members/louis-j-sheehan-esquire.html

Mauritius, a remote island in the Indian Ocean, lost many of its unique creatures after Europeans colonized the island in the 17th century. Besides its most famous extinction, the dodo, the island has lost giant tortoises, pigeons, fruit bats and a giant lizard, says Dennis M. Hansen, a tropical ecologist at Stanford University. Those die-offs now threaten many of the island’s plants, especially the species that depend on frugivores to disperse their seeds.

Take, for example, Syzygium mammillatum, a critically endangered species of tree that grows between 2.5 and 9 meters tall and is found only on Mauritius. The fruit of this tree, rather than developing on branches, forms on the lowermost portion of its trunk, Hansen says. In one of the few pristine areas of forest left on the island — a 24-hectare conservation area that has been fenced off and weeded since it was established in 1996 — Hansen and his colleagues found no S. mammillatum seedlings or saplings more than two meters away from adult trees. At such proximity, young trees would be more susceptible to diseases or fungi that might afflict the adult tree, as well as foraging herbivores.

When the researchers fed S. mammillatum fruit to turkeys, a possible ecological analogue of the dodo, none of the thin-hulled seeds survived passage through the bird’s digestive tract. In similar tests, about 15 percent of the seeds from fruit fed to giant Aldabran tortoises passed through the reptiles unscathed. Neither of the species were native to the island.

Hansen and his colleagues then scattered some of the gut-passed seeds and covered them with a one-centimeter layer of tortoise dung in plots about 20 meters away from adult S. mammillatum trees. The scientists also scattered fruit and bare seeds at sites about one meter from an adult tree and at spots about 25 meters away.

The field tests revealed that S. mammillatum seedlings from gut-passed seeds grew taller, had more leaves and suffered less damage from natural enemies such as insects than other seedlings did. These results indicate that the Aldabran tortoises could replace the now-missing seed dispersers of S. mammillatum, thereby enhancing conservation efforts for the tree, the researchers report in the May 7 PLoS ONE.

Hansen and his colleagues “are certainly doing some very interesting and inspiring research in getting to the nitty-gritty of plant reproductive failure in devastated ecosystems,” says Anthony Cheke, an island ecologist formerly at Oxford University in England who has studied ecosystems on Mauritius and nearby islands since the 1970s. The results offer hope that threatened plants, of which there are many on Mauritius, can proliferate if appropriate seed dispersers are reintroduced to the island.
http://www.theenvironmentsite.org/forum/members/louis-j-sheehan-esquire.html

Despite the apparent success of the experiments in bolstering the reproduction of S. mammillatum, however, scientists seeking to introduce one species to take the ecological place of one that has died out should proceed with caution, says Douglas J. Levey, an evolutionary ecologist at the University of Florida in Gainesville. “An exotic species is an exotic species, even if there was a similar species there before,” he notes. “There always seem to be surprises, despite good intentions, especially in island ecosystems,” he adds.