DNA strand double helix 311.
(photo credit: Jerome Walker)
It may not be long before people will order a test to accurately predict how
long they will live.
This could result from the discovery by a University
of Glasgow team in Scotland showing that telomere length on the ends of DNA in
their genes in early-life predicts lifespans.
A telomere, from the Greek
words “end” and “part,” is a region of repetitive DNA sequences at the end of a
chromosome and serves like a cap on shoelaces that prevents unravelling. The
telomeres protect the end of the chromosomes in the genes from breaking down or
melding with chromosomes near them. Chromosome ends naturally become shorter due
to cell division.
As cells divide, enzymes that duplicate DNA cannot
continue this process all the way to the end of the chromosomes. If cells
divided without telomeres, they would lose the ends of their chromosomes, and
the vital data they contain.
While the telomeres are “chewed up” during
cell division, they are rebuilt by an enzyme called telomerase reverse
transcriptase. This process occurs in most plants, animals and humans,
Prof. Pat Monaghan headed the Glasgow team that on Tuesday
published their findings in the American Proceedings of the National Academy of
Sciences. The researchers were the first to measure telomere length in the young
and then repeatedly during the rest of their natural lives. They found telomere
length in early-life is strongly predictive of the individual’s subsequent
The researchers measured telomere lengths in small samples of
blood cells taken at various ages in a group of zebra finches – small black-,
white- , orange-, and gray-striped and -spotted birds – whose lifespan varied
from just 210 days to almost nine years. The best predictor of longevity was the
telomere length at just 25 days.
Researcher Dr. Britt Heidinger said
“while there was a lot of variation among individuals in telomere length, those
birds that lived longest had the longest telomeres at every measurement point.”
It is known that the variation in telomere length is partly inherited, but also
varies due to variation in environmental factors such as exposure to
Prof. Karen B. Avraham – a leading member of the department of
human molecula genetics and biochemistry at Tel Aviv University’s Sackler
Faculty of Medicine commented on the research.
“This discovery is a
dramatic one, showing the strength of using model organisms to tell us about
normal human health and disease. If a correlation between zebra finches and
humans turns out to be relevant for telomere length and longevity, I predict it
is a matter of time before we will all want to test the length of our
telomeres,” she said. “The take-home message here should also be to reduce
stress in our life from as early an age as possible – this may help us live
Monaghan also emphasized the importance of early-life
“Our study shows the great importance of processes
[occurring] early in life. We now need to know more about how early life
conditions can influence the pattern of telomere loss and the relative
importance of inherited and environmental factors. This is the main focus of our
current research,” she said.