November 20, 2012
Telomere Length In Chromosomes Can Predict Longevity In The Wild
Brett Smith for redOrbit.com - Your Universe Online
New research from the University of East Anglia in the UK has found a correlation among biological age, longevity and an individual´s DNA.By studying a wild population of Seychelles Warblers on a small island, the geneticists were able to demonstrate how the end-caps of chromosomes, known as telomeres, shorten due to age and stress, and can be an indication of life expectancy.
"Over time these telomeres get broken down and become shorter. When they reach a critical short length they cause the cells they are in to stop functioning,” said the study´s lead author David Richardson. “This mechanism has evolved to prevent cells replicating out of control — becoming cancerous. However the flip side is that as these zombie cells build up in our organs it leads to their degeneration - ageing - and consequently to health issues and eventually death.”
The project spanned 20 years and is the first to measure telomere length across the entire lifespan of an animal.
"We investigated whether, at any given age, their telomere lengths could predict imminent death,” Richardson said. “We found that short and rapidly shortening telomeres were a good indication that the bird would die within a year.”
"We also found that individuals with longer telomeres had longer life spans overall,” he added.
Richardson noted that this type of research could have ramifications for human senescence studies, but the study itself would be difficult to replicate on human subjects.
"It would be virtually impossible to do such a study in humans," said Dr Richardson. "For one thing it would take a very long time to study a human lifespan. Also in humans we would normally, quite rightly, intervene in cases of disease, so it wouldn't be a natural study.”
Throughout the course of their lifetime, the birds in the study underwent various types of biological stress and that stress was reflected in the status of their telomeres.
"We found that telomeres are linked to body condition and reflect the history of oxidative stress that has occurred within an individual's lifetime,” Richardson said. “The healthier you are, or have been, the better telomeres you have. But it's hard to know whether this is a consequence of being healthy, or a cause.”
He suggested that this portion of the study could be translated to include humans.
"Oxidants attack telomeres. So things like smoking, eating foods that are bad for you, and putting your body through extreme physical or mental stress all have a shortening affect on telomeres,” Richardson said. "All these stresses do damage to our bodies. You hear people saying 'oh they look like they've had a hard life'. This is why. A shortened telomere shows an accumulation of damage life has done to you."
The British study comes just after US researchers at Harvard published a report identifying a gene variant that determines not only if a person is an ℠early riser´ or ℠night owl´, but also the time of day that person is most likely to die based on their circadian rhythms.