Longevity mutation found in flies 'far-reaching'

Researchers have said that a particularly important variation of the gene with much the same life-governing consequences has actually been widespread among fruit flies, judging by lines gathered from the wild across the entire globe for 60 years.

The naturally occurring variation is the insertion of a transposable element - an invasive snippet of DNA - at a specific position on Indy. Researchers, including Brown University biology professors Stephen Helfand and Robert Reenan, found that the transposable element, called Hoppel, was present to varying extents in 17 of 22 fruit fly lines gathered from all over the world as far back as the middle of last century.

Hoppel was present in 100 percent of a captive fly line started in 2006 in Mumbai, India, for example, and 55 percent of flies descended from those gathered in Oahu, Hawaii, in 1955.

The researchers, led by postdoctoral scholar Chen-Tseh Zhu, measured the physiological effects of Hoppel by looking at flies from three different lines: one from Oahu gathered in 1950s, another from Captain Cook, Hawaii, gathered in 2007, and one with its origin in Hidalgo, Mexico, in 2005. Each line had some flies with at least one copy of Indy with Hoppel and some with no Hoppel in Indy.

The heterozygous females in these lines ended up laying about 10 percent more eggs than flies that had no Indy alleles with Hoppel. Flies for whom both Indy alleles had Hoppel laid the fewest eggs. This demonstrates that one Indy allele with Hoppel had a strong selective advantage in reproductive fitness, Helfand said.

The study has been published online in the journal Aging.