Inside a lab at NC State, hundreds of fruit flies are up to no good. In one set of test tubes, 30 of them are falling down drunk. Nearby, dozens more are getting into food fights. It’s the kind of behavior we usually ascribe to a poor upbringing. But, says researcher Trudy Mackay, the key to complex traits like aggression and alcohol tolerance may lie in the flies’ genes.
And in ours.
Mackay was elected to the National Academy of Sciences in 2010 for research that examines how physical and behavioral traits are affected by genes and the environment. Since all organisms have similar genetic systems, her work with fruit flies could lead to advances in the treatment of human diseases. It could also help doctors develop treatments tailored to individual patients based on their genomic profile.
Mackay spent a year inbreeding 200 strains of fruit flies she captured at the farmers market near campus. Twenty generations later, the insects in each line are genetically identical to each other but different from members of other strains.
For the study on alcohol tolerance, she introduced ethanol vapor into several test tubes, then measured how long it took the flies to pass out. By comparing the flies’ gene sequences, Mackay soon isolated several genes that play a role in metabolizing alcohol. For the study on aggression, she forced a group of flies to compete for a small amount of food. The aggressive flies had slight genetic differences compared to the passive flies.
Mackay’s next challenge is to find the biological pathways that translate genetic differences into cellular changes.
“It’s a great unsolved puzzle,” she says. “But once we understand the genetics behind complex traits we will transform medicine. Treatment won’t have to be trial-and-error.”