Birds with the longest chromosome caps live the longest

The best evidence yet that telomere length correlates with life span: zebra finches with longer telomeres live longer. Longevity was best predicted in prepubescent chicks. Human tests still iffy.
Written by Janet Fang, Contributor

Last year, labs around the world starting selling blood tests that tell you how long you will live.
Sort of.

The tests measure telomeres, the little caps of DNA at the tips of chromosomes that shorten as we age. The science behind the tests seem obvious, but the link between longer telomeres and longer lives have remained unproven.

NOW, scientists show that those with longer telomeres live longer… at least in finches for now. Still, it’s the first time this has been shown for any species.

Telomere shortening has been linked to both normal aging and to various degenerative diseases… but studies of the relationship between telomere length and longevity have been hampered by the time scale over which individuals need to be followed. It’s hard with people and other long-lived species where the variation in lifespan is greatest.

Pat Monaghan and colleagues from University of Glasgow measured the telomere length in 99 zebra finches (Taeniopygia guttata, pictured). The birds resemble long-lived animals with little restoration of telomeres in body cells as they age.

The key problem in those previous studies, says Monaghan, is that researchers took samples only once or twice from a single individual during their lifetime, rather than sampling periodically.

So instead, the team took blood samples from the birds, starting in their lil’ nestling stage all the way through their natural lifespan of up to 9 years.

The researchers found telomere length to be a very strong predictor of observed lifespan. In particular, chicks who had the longest telomeres when they were 25 days old turned out to be the longest lived. (The closest analogy is probably to a prepubescent human.)

It’s the first time that normal differences in telomere length have been shown to be predictive of longevity.

"So far studies just looked at individuals that were already quite old," Monaghan says. "But if you look at telomeres in old age, then those individuals with the shortest telomeres will have already died." This means we need to know more about how early life conditions can influence telomere loss, something we’ve been ignoring thus far.

The results were reported in Proceedings of the National Academy of Sciences today.

Via Nature, ScienceNOW.

Image: young, middle-aged, and old zebra finches / Paul Jerem

This post was originally published on Smartplanet.com

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