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The royal genome
Swiss prize funds study of aging in ants
  
By
Edward R. Winstead



Queen Solenopsis invicta and brood.

The queen ant as teenager makes sense: She is the center of a world that exists only to serve her, and there is no life after age 30.

In fact, many queen ants live to be teenagers and twenty-somethings (the oldest ant on record was a queen who reportedly lived to the ripe old age of 29). Her majesty's attex ndants, however, die relatively young. In a colony, the queen lives 500 times longer than the males and 50 times longer than non-reproductive females, or worker ants. All ant genomes—royal or otherwise—are essentially the same, raising the question: Why do individuals with the same genome have such different life spans?


Seven genes in young, old, and very old ants

The social organization of a colony plays a role in longevity, according to Laurent Keller, an entomologist who recently compared the life cycle of 180 species of insects. Indeed, a 29-year-old ant has lived 100 times longer than non-social insects such as flies or dragonflies ever will. But Keller thinks a queen's long life is due to innovations in the genome as well as pampering. While ants all share the same genes, he says, longevity may depend on a cell's ability to slow aging by making molecular repairs as problems arise.

Keller, director of the Institute of Ecology of the University of Lausanne, Switzerland, has turned from the social life of ants to their genome. He recently won a prize from the Leenaards Foundation in Switzerland to fund research on aging in ants. Keller will hunt for the ant version of seven genes linked to aging in humans, fruit flies, and worms. "We intend to study genes involved in DNA maintenance and genes that regulate the cell cycle, for instance," says Keller.

Then, the researchers will compare the activity of the seven genes in young, old, and very old ants of a single species. If Keller's hunch is correct, certain genes are expressed differently in queen, male, and worker ants. Variations in gene activity may be a kind of mechanism that can delay the moment at which the queen begins to deteriorate.


A gene causes workers to kill the queen

If successful, Keller may repeat the study in different species of ants, including those that have more than one queen to a colony. Ants come in some 12,000 varieties, and longevity has been associated with how many reproductive females sustain a community. The lone queen usually lives much longer than a queen that shares her colony.

"Very little is known about the ant genome," says Keller. But, he adds, ants offer a unique model system for studying aging because the range of life expectancy in ants isn't found elsewhere in nature. The primate equivalent to a 29-year-old ant, he explains, would be a 10,000-year-old monkey.

The ant genome has already provided scientists with one major surprise. Two years ago, Keller and Kenneth Ross, of the University of Georgia, discovered a gene in queen ants that causes worker ants to attack and kill them. Why this happens is a mystery, but the researchers suspect that a chemical signal is involved. Whatever the signal, workers certainly know whom to execute: DNA tests showed that none of the murders was a case of mistaken identity.

"This gene has very drastic effects on social behavior," says Ross. The gene was discovered accidentally during a search for biological markers in the genome of North American fire ants. His laboratory expects to have the gene sequence later this year.

The Leenaards Prize for 2000 was awarded to three researchers, including Laurent Keller. Since 1980, the Swiss Leenaards Foundation has supported research in a number of areas, including culture, health, and science.

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