Within almost every animal there is a ticking clock that contributes to determining their lifespan. Each time that a cell divides, the capping structures that protect the ends of chromosomes – known as telomeres – become shorter, and the length of these structures is correlated with life expectancy. However, it was unclear how this alarm clock performs in one small mammal, the edible dormouse, which has a life expectancy that is 50% greater than that of other similarly sized mammals. Knowing that hibernation slows cellular damage and that the small rodents can spend as much as 11.4 months out of every year hibernating, Franz Hoelzl and colleagues from the University of Veterinary Medicine, Austria, wondered what effect the dormouse's lethargic lifestyle might have on their telomere length.
After monitoring the body temperature (which is a good indicator of when an animal is active or hibernating) of wild dormice in the Vienna woods over 12 months and gently collecting cells from the animals’ mouths at the beginning and end of the period to measure their telomere length, Hoelzl and colleagues compared the length of the animals’ telomeres with their activity pattern. However, the team was surprised to discover that the drop in body temperature that occurs during hibernation was not correlated with reductions in the length of the animals’ telomeres. Instead, the rate at which the animals emerged from hibernation – which they do periodically over a hibernation season – was the best indicator of the rate of telomere loss. However, the animals appeared to compensate for the loss and were able to elongate their telomeres during the active season, but only if food was plentiful.
