Little Green Bacteria?

One of the most tantalizing questions facing scientists is whether life could exist on Mars. Now, a University of Arkansas researcher has produced new evidence that primitive bacteria could survive in the harsh conditions on the Red Planet.

Timothy A. Kral tried to approximate Martian conditions by mixing ash from Hawaiian volcanoes, which is known to share certain chemical characteristics found in Martian soil, with carbon dioxide, hydrogen and various amounts of water in test tubes.

Kral then added a very primitive type of bacteria known as methanogens, which are found deep in the ocean, in Earth's crust and in cows' stomachs. The microbes don't need oxygen to survive, existing instead on nitrogen and hydrogen to make methane.

In Kral's experiments, described last week at a meeting of the American Society for Microbiology in Chicago, the bacteria grew in the simulated Martian soil, even when water was extremely limited, as it is believed to be on Mars.

Thigh Cream: Pulling Your Leg

Bad news for women looking for an easy way to thin their thighs: A new study finds that so-called thigh-reducing creams are ineffective.

Bonita Marks of the University of North Carolina at Chapel Hill and colleagues asked 11 students age 18 to 35 to rub "thigh-reducing" cream on one leg and a useless cream on the other, without knowing which was which, for six weeks. The researchers measured each woman's thigh in three places before and after the cream.

"Not only did we find no difference in each volunteer's thighs at the end, but the volunteers themselves said they could see and feel no difference either," said Marks, who presented the findings last week at a meeting of the American College of Sports Medicine in Seattle.

Sentinels and Selfishness

Some disheartening news from the animal kingdom for those who sentimentalize the seemingly selfless behavior of some creatures:

T.H. Clutton-Brock of the University of Cambridge in England and colleagues spent some 2,000 hours observing a wild population of meerkats in the South African desert. Meerkats, a type of mongoose, often post one sentinel to warn other meerkats if a predator is approaching.

The assumption had been that whichever meerkat was standing guard was essentially performing a selfless act, putting itself in danger for the greater good of protecting its comrades, and that the meerkats would take turns, sharing the danger.

But according to a report in the June 4 Science, the sentinel meerkats were actually less likely to be attacked. Moreover, experiments with bits of hard-boiled egg showed that the sentinels would stand guard only as long as they had enough to eat. And there was no discernible equitable rotation.

"The selfless behavior of sentinels . . . has always been a human activity that people want to believe is found in other species too," writes Daniel T. Blumstein of the Macquarie University in Australia in an accompanying commentary. The new research "dispels the myth of kinship and instead supports the opposing view that sentinel behavior is a selfish, not selfless, activity."

The meerkats are not entirely selfish, however. "For the first three weeks after the birth of a litter, one individual in each group stayed at the burrow to 'baby-sit' the pups for a day at a time, losing 1 percent to 2 percent of their body weight per day spent babysitting," the researchers write.

Zzzzzt--You're Sick!

Electric bug zappers may not be hazardous only to the health of flying pests--they also may spread viruses and bacteria the insects carry.

Alberto Broce and James Urban of Kansas State University studied bug zappers by putting microorganisms on flies and measuring how far the microbes flew when the insects were zapped. They found that microbes could be spread as far as six feet.

The zappers, which lure insects with light to an electrified metal grid, do not generate enough heat to necessarily kill any viruses or bacteria on a fly's body or in its digestive track, the researchers say. That means whatever the bug is carrying can be showered down around the zapper when the hapless bug explodes.

Based on the findings, presented last week at a meeting of the American Society for Microbiology in Chicago, the researchers recommend that the devices not be used near food, such as close to the backyard barbecue.

CAPTION: This furry sentinel may be looking out for his fellow meerkat, but it's not because he's a great guy.