Alcoholism is linked to genes in fruit flies -- and humans
that the genetic make-up of an individual -- apart from environmental factors -- affects the tendency of alcoholism is widely accepted by scientists. "It would be safe to say that the contribution is half and half," says Irving Gotteman of the University of Virginia, Charlottesville, usa , who has studied the incidence of alcoholism in identical twins and in unrelated families. Researchers at the Gallo Center of the University of Southern California, San Francisco, are now looking for genes responsible for this phenomenon ( New Scientist , Vol 154, No 2078).
The researchers noted a striking similarity in the effect of alcohol on fruit flies ( Drosophila Melanogaster ) and humans. After consuming alcohol, they stumble around, fall over, and eventually pass out. Efforts are on to isolate the gene that makes them vulnerable to liquor. The researchers say that people who take a lot of drinks to become drunk are genetically predisposed to alcoholism.
If the research team can devise a system to control this gene, it will be possible to chemically switch off the genes responsible for alcohol tolerance. "The genes we carry have many counterparts in fruit flies," says Ed Lewis, geneticist at the California Institute of Technology, Pasadena. There is likelihood of these genetic pathways, that affect behaviour, carrying over to humans, he adds.
The research team genetically engineered numerous fruit flies to have short sections of dna randomly inserted into different genes, to disrupt their function. The mutant flies were placed in a tall glass cylinder with a miniature staircase mounted at 45 degrees known as an 'inebriometer'. Ethanol vapour was let into the cylinder. As the flies became intoxicated, they increasingly lost their balance and stumbled into a glass container at the bottom of the cylinder. The more susceptible flies passed out in about 13 minutes whereas the more stubborn ones took about 32 minutes.
The difference between the two groups of flies was put to test. The gene sequences of the flies revealed that five previously identified genes were linked to susceptibility and tolerance of alcohol. Mutations in the genes made the flies more vulnerable to the effects of alcohol. Previous research has shown that malfunction in these genes makes the flies lose their sense of place.
Though the research provides answers to a lot of questions regarding alcoholism, a treatment based on the findings is still far away.
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