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In the meantime, Bülow advises cancer patients not to try to lose weight. “It’s weight loss induced by cancer that often kills these patients,” he says. —C. BROWNLEE

This Week

A Whale’s Tale

facet of obesity is responsible for the increased cancer risk.

Several years ago, Allan Conney of Rut-gers University in Piscataway, N. J., and his colleagues noticed that when lab mice were exposed to ultraviolet (UV) light and then given caffeine or encouraged to exercise regularly on a running wheel, they were less likely to get skin cancer than were UV–exposed mice that didn’t receive these interventions. Since both caffeine and exercise decreased the animals’ body fat, the researchers wondered whether fat itself might be the deciding factor in cancer susceptibility.

In a new experiment, Conney’s team separated mice into two groups. Only one group of animals was placed in cages with exercise wheels.

After 2 weeks, all the animals were similar weights, but those in the running group had significantly more muscle and less body fat than the non-exercisers did.

After researchers exposed the animals’ skin to UV light, lab tests showed that the light-damaged cells in the runners were twice as likely to die as were cells in the non-exercisers. This cell death stopped the majority of damaged cells from developing into tumors.

Working with some mice that had formed tumors, Conney’s team found a similar effect: Tumor cells in exercisers were more likely to die spontaneously than were tumor cells in sedentary mice.

To make sure that these effects weren’t purely due to physical activity, the researchers surgically removed a layer of fat from the bellies of some non-exercising mice, and then exposed them and other non-exercisers to UV. Twice as many UV-damaged cells and tumor cells died in the surgically lean animals as in the animals that had retained the fat. The team reports its findings online Oct. 23 and in an upcoming Proceedings of the National Academy of Sciences.

Conney and his colleagues suggest that body fat might be leaching some substance that keeps damaged and cancerous cells alive. “Fat secretes a lot of different substances—it’s not an inert tissue,” says Conney.

Jens Bülow, who studies obesity at Bis-pebjerg Hospital in Copenhagen, finds the researchers’ speculation plausible. He notes that if further studies can track down the cancer-supporting substance, researchers might be able to develop drugs to block its action.

Puzzling marine
compounds are natural

An 85-year-old vial of oil from a whaling ship has revealed that a mysterious group of organic chemicals resembling human-made compounds are naturally produced in the sea.

A decade ago, scientists monitoring marine mammals’ flesh for pollutants began finding unknown organic compounds containing the halogen atoms bromine and chlorine. More than 20 such compounds were eventually revealed. That raised alarms because the compounds, as complex halogenated chemicals, structurally resemble the pesticide DDT and polychlo-rinated biphenyls (PCBs), which were once used in flame retardants.

Manufacture of those and similar chemicals began in the 1930s. But their production and use were banned in most countries decades ago, after they were found to be deadly pollutants. Because halogenated compounds break down extremely slowly, they persist in soil and water and accumulate in animal flesh.

Researchers wondered whether the recently discovered organic chemicals were manufactured or produced naturally. Symbiotic bacteria in ocean sponges, for example, produce chemicals similar to DDT and PCBs that deter fungal growth.

To investigate, Emma L. Teuten of the University of Plymouth in England and Christo-

pher M. Reddy of the Woods Hole (Mass.) Oceanographic Institution analyzed a whale-oil sample from 1921, before industry produced the first halogenated chemicals.

Their sample came from a jar of the translucent, yellow, odorless oil found on the Charles W. Morgan, one of the last whaling ships in operation. The ship is now preserved and on display in Mystic, Conn. “We were incredibly lucky to acquire it,” Reddy says.

The scientists found 11 of the organic compounds in the whale oil. Because of the oil’s age, the 11 compounds must have been produced naturally, the scientists conclude in their report online and in an upcoming Environmental Pollution.

“This by no means puts the chemical industry off the hook,” Reddy says. Industry will probably be pleased to hear that it isn’t responsible for the cleanup of additional compounds, he says, but the study “doesn’t say that Monsanto, the main producer of PCBs, is not responsible for PCBs that are found in the environment.”

The researchers argue that the naturally occurring compounds can shed light on the fates of the similar human-made ones. The recently discovered compounds must have been around far longer than DDT or PCBs, Teuten says, so researchers may be able to study the natural halogenated compounds to find out how industrial chemicals will continue to affect the environment.

Teuten and her colleagues say that they hope to determine where the new compounds are coming from and why they are being produced. The researchers are just beginning work to find out whether the compounds are toxic.

“I think the study is fantastic,” says Gordon W. Gribble of Dartmouth College in Hanover, N.H. Their work “really does show that nature makes these compounds.” —J. REHMEYER

A SHIP’S SECRET The Charles W. Morgan, one of the last whaling ships operating during the 19th and early 20th centuries, still carried whale oil from a late voyage. Analysis of the oil showed that some mysterious compounds that resemble DDT and PCBs are naturally produced.