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Frontlines Photo: Courtesy of Jokn Tooker Imagine the gall Humans don't usually select mates on the basis of their gall, but the male gall wasp does. Antistrophus rufus can search through a maze of dead plants and locate an inconspicuous gall that houses his intended bride, thanks to his ability to detect modified plant chemicals. Graduate student John Tooker and adviser Lawrence Hanks were studying wasp sympatric speciation, examining the chemical cues that gall wasps use to distinguish plants. Hanks, at the entomology department, University of Illinois, Urbana-Champaign, calls the additional findings "fortuitous" (J.F. Tooker et al., "Altered host plant volatiles are proxies for sex pheromones in the gall wasp Antistrophus rufus," Proceedings of the National Academy of Sciences, available online at www.pnas.org/cgi/doi/10.1073/pnas.252626799). They studied two species of host plants and found that the male wasps could differentiate between the two plants, with a preference for the kind in which they were born. They further found that the two subpopulations of wasps--one that hatched in one plant species and another that hatched in a related plant--were reproductively isolated and probably two separate species. The two species of plants contain different amounts of volatile compounds, and the male wasps selected for their natal plant's signature. Furthermore, galled plants produce slightly different ratios of these compounds. Thus, they concluded that the male wasps, which hatch before females, could select the right plant and wait at the gall for the emergence of the perfect mate--a result of the plant's chemical response to the gall-making process. --Myrna E. Watanabe Photo: Courtesy of Peggy Greb, ARS Photo Library Carcinogens in the holiday dinner Planning on eating roast turkey, sweet potato, and pumpkin pie for holiday dinner? Then you will also consume a sampling of mutagens and carcinogens, including heterocyclic amines, furfural, coumarin, and benzo(a)pyrene. A tongue-in-cheek but true holiday dinner menu, offered by the New York-based American Council on Science and Health (ACSH), is available online at www.acsh.org/publications/booklets/menu02.html. The message is dual: "Many chemicals naturally in our foods can cause cancer when they are fed to animals in long-term, high-dose tests. This does not necessarily translate into a human cancer risk," explains Ruth Kava, director of nutrition at the organization. "Second, there is no scientific reason to believe that because a chemical is man-made, it necessarily is more dangerous than one that is present naturally. Or, that a 'natural' chemical is necessarily safer than a synthetic one." ACSH doesn't claim credit for the menu idea, however. "I got it from reading a speech in Nutrition Today--around the mid-1970s when I was writing my book Panic in the Pantry," relates ACSH president Elizabeth Whelan. "The author had used the dinner menu at a meeting he was addressing and went course by course on toxins and carcinogens," she adds. The 2002 menu may attract more attention than editions past because of the recent flak over acrylamides in french fries and changing US requirements for organic foods. These events "may have people thinking about what labels and production methods really mean," says Kava. --Ricki Lewis Image: Erica P. Johnson Brain-based binging A reward center in the brain that plays a key role in maintaining drug addiction also appears to influence overeating in rats, according to research presented at this year's Society for Neuroscience meeting. The nucleus accumbens has direct links to the hypothalamus, which helps regulate eating, notes psychiatry professor Ann Kelley, University of Wisconsin-Madison. When opioid peptides, which stimulate the system, are injected into a rat's nucleus accumbens, "they end up eating huge amounts of food they wouldn't normally eat," she says. This finding helps explain why some people eat fatty, salty foods, even when they're not hungry. "The implication would be that this neurochemical system is responsible for that behavior," she says. Normally, rats will eat about three to five grams of fat. But when the nucleus accumbens is stimulated, "the rats will sometimes eat 15 to 20 grams at one sitting," she notes. The amygdala, a brain structure connected to the nucleus accumbens and more often associated with fear and anxiety, also plays a role in eating, Kelley says. "If we inactivate a certain part [basal lateral] of the amygdala, the animals just eat the same amount they would if they don't have the opioids. You completely reduce this enhancement of palatability. The animals don't binge. Our data say that basically without the amygdala, yummy, unneeded food would not give us the same rush." --Harvey Black

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