Estrogen Mimics a Threat?
The Environmental Protection Agency wants to know whether pollutants that mimic estrogen cause reproductive problems in people, such as lowering sperm counts. But new research suggests that may be harder to test than had been thought.
Jimmy L. Spearow of the University of California at Davis and colleagues discovered that different strains of mice used for laboratory testing vary sharply in how they react to estrogen. Some young male mice injected with estrogen experience significant problems, such as smaller testes and lower sperm production. But others are essentially unaffected.
"The use of laboratory animals that genetically are quite resistant to estrogen for the evaluation of possible reproductive effects of various chemicals might be misleading and may mask our appreciation of how global exposure to estrogen-like compounds threatens wildlife, domestic animals and our own species," said Spearow, who reports his findings in the Aug. 20 issue of the journal Science.
Bombardier beetles defend themselves by spraying assailants with a boiling hot, toxic liquid discharged from the tips of their abdomens.
To determine just how adept these insects are at hitting their targets, Thomas Eisner and Daniel J. Aneshansley of Cornell University took close-up photographs of the beetles as the researchers pinched and poked various parts of their bodies.
"There is virtually no site on the beetle's body where an ant could inflict a bite without entailing the risk of being sprayed in return," the researchers conclude in the Aug. 17 issue of the journal Proceedings of the National Academy of Sciences.
This is important to the beetles because they live in the dirt in Kenya and are vulnerable to ant assaults despite their ability to fly. "To activate the wings, they must first unfurl these from beneath the wing covers, and this takes time," the researchers write. "Delays are unaffordable in emergencies, and it should come as no surprise that many beetles have evolved means for 'buying time' when under attack."
It remains unclear, however, "how the beetle, which inevitably drenches itself when discharging, withstands the heat and irritancy of its own spray."
Southeast Asia's Striped Rabbit
Conservationists have discovered another unusual mammal living in the remote mountains of Southeast Asia--a unique species of striped rabbit that scurries through the underbrush of the Annamite mountains in Laos and Vietnam.
Wildlife Conservation Society researcher Robert J. Timmins first spotted carcasses of the rabbits being sold for food in a market in the rural town of Ban Lak in Laos in 1995 and 1996. The rabbit, which has distinctive dark brown stripes running down its face and back, a reddish rump and short ears, was later photographed alive by an automatic camera in the Pu Mat Nature Reserve in Vietnam.
Anatomical and genetic studies showed the rabbits are related to another species of rabbit found 1,000 miles away on the Indonesian island of Sumatra. The two species apparently diverged evolutionarily about 8 million years ago, the researchers report in the Aug. 19 issue of the journal Nature.
"Our discovery of the rabbit in the Annamite mountains may provide insight into the factors governing current patterns of biodiversity in Southeast Asia, leading to its protection in the future," they wrote.
Several other unusual mammals have been found in the region in recent years, including a barking deer called the giant muntjac and the Vietnamese warty hog.
Analyzing Midnight Munchies
For some people, late-night trips to the fridge for some munchies are not just an innocent indulgence. They have "night-eating syndrome," an often-serious condition that most commonly occurs among people who are obese.
Although the condition has been recognized since 1995, it has not been subjected to much intensive research. Now, however, an international team of researchers has attempted to carefully study people suffering from the problem.
The researchers at the University of Pennsylvania and at the University Hospital in Norway examined 22 "night-eaters," comparing their behavior and hormone levels with 22 people without the syndrome.
The night-eaters are much more likely to awaken during the night and to eat after they wake up, the researchers found. They also have abnormal levels of certain hormones, including melatonin, which is involved in sleep regulation, and leptin, which is involved in regulating hunger.
"Night-eating syndrome appears to represent a new eating disorder, different from the established disorders of anorexia nervosa, bulimia nervosa, and binge-eating disorder," the researchers wrote in the Aug. 18 Journal of the American Medical Association.
The findings suggest, the researchers say, that it may be possible to treat the syndrome by altering some of the hormones that are abnormal.
CAPTION: Researchers used close-up photography to study how bombardier beetles aim their defensive sprays.