Scientists have been able to double the life spans of fruit flies by manipulating one of their genes. Someday soon, they may be able to do it for us. Scientists have named the gene INDY for "I?m Not Dead Yet."
Flies with a mutation in the INDY gene have lived for 71 to 110 days, more than twice as long as their usual life span of 37 days. The long-lived flies appear to be as healthy as normal flies, and continue to reproduce into old age.
The INDY gene is involved in metabolism, making it slightly more difficult for flies to absorb the calories in food. Scientists have found that yeast, worm and rodents live longer when they are slightly starved. There is even a scientist who is experimenting on himself by eating an extremely reduced diet of 40% fewer calories than normal, to see if he lives a longer than average life.
If we can learn how to manipulate the same gene in human beings, we may be able to live longer without starving ourselves. And we would solve the biggest problem of extended age: We keep people alive in nursing homes, but are their lives really worth living?
"I think it?s terrific," said Dr. James R. Carey of the University of California. "They?ve known for a long time that caloric restriction extends life spans, but no one has nailed down a mechanism. That?s why this is really important."
Researchers are amazed that a single gene could have such a large effect on an organism. It hasn?t been easy to locate the INDY gene. "It has been very hard to find a mutation that abolishes aging," said Dr. Michael Rose, who also does research at the University of California. "You can find mutations that abolish vision or coordination or courtship." Earlier methods to extend the lives of fruit flies led to terrible consequences, such as starvation or lack of reproductive ability.
Why would calorie restriction lead to longer life? For one thing, it decreases the production of the sex hormones, estrogen and testosterone. We know that anorexic girls have low levels of estrogen and that sometimes very athletic girls, who have a higher than normal degree of muscle tissue and therefore less fat, do too, because estrogen is produced in the body?s fat cells. One of the primary goals of nature is for every species to reproduce, so it?s natural that a delay in puberty would extend life, as our bodies wait for a change to produce offspring. Decreased sex hormones also cause increased production of stress-related proteins, which slow the rate of cell turnover.
Those of us with weight problems are wondering if this type of genetic manipulation, which slows the absorption of calories, might also be a breakthrough in weight control for the future.
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