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Release: Feb. 7, 2000

UI researcher studies love song of fruit fly

IOWA CITY, Iowa -- Dan Eberl is always on the lookout for love songs, but not the kind played on the radio or in a Las Vegas lounge act.

That's because Eberl, a University of Iowa biology professor, is interested in a very special kind of song -- the "love song" of the fruit fly.

Although it may seem an odd choice, the fruit fly and its love song are very effective tools for learning about the molecular and cellular mechanisms involved in hearing in other insects and in animals. In fact, says Eberl in an article published in a recent issue of the journal Current Opinion in Neurobiology, studying the fruit fly may one day help scientists to better understand human hearing.

Funded by a three-year, $225,000 grant from the Whitehall Foundation, Eberl is trying to identify the genes involved in the various molecular processes that enable fruit flies to hear their love song.

"My job is to identify the genes responsible for hearing in fruit flies. The whole field of identifying genes related to deafness and hearing has blossomed in the last five years," says Eberl, who spent one year at SUNY, Stony Brook and five years at Harvard Medical School before coming to the UI last year. "Fruit flies use antennas for hearing. The cells that detect the antennal vibrations appear to share molecular mechanisms with bristles used for the sense of touch. The receptors for hearing in vertebrates (including humans) are structurally halfway between the two types. This means that insect hearing may be related to human hearing."

The fruit fly love song plays a pivotal role in helping Eberl separate fruit flies into two groups -- hearing and non-hearing -- so that he can compare and contrast the genes responsible for hearing. It begins with the fruit fly courting ritual. The male extends one wing and vibrates it in such a way as to create the love song. Most females and males hear the song and respond in a sex-specific manner, however some flies fail to respond and are thought to be deaf. Eberl implants electrodes into the antennas of the unresponsive flies, as well as a group of normal flies, and records the voltages the receptor cells generate as the flies listen to the love song. By comparing the electrical impulses generated by the normal flies to those generated by unresponsive flies that are believed to be deaf, Eberl is able to distinguish the truly deaf flies from those who may be able to hear but for some other reason fail to respond.

Within this group of truly deaf fruit flies, Eberl found several mutants lacking genes needed to hear the love song. For example, he identified one fly strain, nicknamed Beethoven, having a genetic mutation that disrupts the structure and function of the hearing organ in the fruit fly antenna.

"Identifying the gene product of Beethoven and other such genes and examining their functional roles in hearing will provide new insights into auditory mechanisms, not only in fruit flies, but perhaps in humans, as well," Eberl says.