Bane of the fruit bowl is biologists' bug of choice

Time flies like an arrow, fruit flies like bananas, and scientists like fruit flies for biomedical research.

By ROBERT S. BOYD, McClatchy News Service

Last update: March 29, 2008 - 6:17 PM

WASHINGTON

Most people think of fruit flies as annoying little pests zipping around bananas or grapes on the kitchen counter. But to biologists, they're diamonds on the wing.

These miniature aerial acrobats have been a basic tool of biomedical research for nearly a century. They've unlocked many secrets of animal and human genetics, development and evolution, and they continue to provide valuable insights into cancer, heart disease, diabetes, obesity and neurological disorders.

Fruit fly researchers have won two Nobel Prizes, in 1933 and 1995.

After all that time and toil, you might think there's little new to be discovered. But the field is undergoing a revival, attracting thousands of researchers who ground out almost 16,000 scientific papers in the past five years.

The National Institutes of Health (NIH) is investing more than $180 million a year in their work, according to Laurie Tompkins, the program director at the NIH's Division of Genetics and Developmental Biology in Bethesda, Md.

"Fruit flies are major contributors to understanding what goes wrong in cells that cause disease," said Lynn Cooley, a geneticist at Yale University in New Haven, Conn. About three-quarters of the human genes associated with disease have counterparts in fruit flies, she said.

"We are in a renaissance period," said Dr. Susan Celniker, a fruit fly expert at the Lawrence Berkeley National Laboratory in Berkeley, Calif. "We now have fly models for all types of human diseases."

The revival is due to recent advances in genetics that allow scientists to decipher the DNA that makes up human, animal and plant genomes. Eleven new fly species' genomes were decoded last year.

Fly researchers used to study genes composed of hundreds or thousands of molecules. Now they can work with great precision at the level of individual molecules.

The formal name of this scientific pet is Drosophila melanogaster, Greek for "black-bellied dew-lover." Most workers in the field simply call themselves "fly people." They go "fly-mining" for new data, which they store in an online "FlyBase." They hoard thousands of live flies in "stock centers" in Bloomington, Ind., and Tucson, Ariz.

Researchers have discovered surprising aspects about the lives of these little creatures. Fruit flies love sweets and suffer from obesity and eating disorders. They have immune systems against viral diseases. They can detect motion 10 times faster than the human eye can, which makes them maddeningly hard to capture.

Fly researchers claim credit for many discoveries connected to human disease.

For example, Tian Xu, a geneticist at the Yale School of Medicine, studies how cancerous cells in flies metastasize, or spread to other cells, similar to the way they do in human malignant tumors.

"Our fly model has distinct advantages for studying the basic biology underlying tumor progression and metastasis," Xu wrote on his website.

A fly gene called "Twist" has a corresponding gene that causes deformities in human embryos when it isn't working right.

Fruit flies are more distant genetically from humans than are mice. But fly researchers say their insects have advantages over laboratory mice. Many basic genes were discovered first in flies, then studied in mice and humans.

"The huge disadvantage of mouse systems is it costs so much to house and feed them," Cooley said. "It's much more difficult to do experiments. It takes a lot longer for generations to develop. We can move a lot faster and cheaper with flies."