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High food availability slows down cell aging

Hibernation was long considered the secret behind the long lifespan — almost 12 years — of the edible dormouse. However, researchers have now found that high food availability during active summer seasons contributes to their long lives. Increased food between hibernations allows a slow down in cell aging.

Telomeres form protective caps at the ends of the chromosomes to prevent the degrading of our genome. When telomeres become too short, cell division is no longer possible with the cell loosing its potential to divide — and thus dies. It was always assumed that slowing down body functions during hibernation was responsible for decreasing the rate of telomere degradation. The edible dormouse would therefore benefit from its long hibernations and add to its long life expectancy.

"Telomeres get shorter with every cell division and are therefore considered a biological marker for ageing."

Franz Hoelzl PhD, Vetmeduni Vienna Research Institute of Wildlife Ecology.

But, Franz Hoelzl PhD and his team demonstrate that hibernation is not the cause for the animals' slowed aging. Especially in their repeated rewarming phases when they rewarm and arouse — scientists found these phases led to tremendous shortening of the animals' telomeres.

The more frequently the animals interrupted their torpor (hibernation) phases, the more their telomere caps were shortened. Showing in terms of telomere shortening, hibernation is not responsible for decreasing the rate of ageing in dormice. So, researchers looked for alternative explanations.

Their study was published in the Journal of Experimental Biology.

"Unexpectedly, the true 'fountain of youth' is high food availability during their active season."

Franz Hoelzl PhD, Department of Integrative Biology and Evolution, University of Veterinary Medicine, Vienna, Austria.

To show this, researchers came up with a very simple and clever experiment. They chose a year with a low abundance of beechnuts, the animals' main natural food source. Then they split the animals into two groups. The diet of the first group was supplemented by sunflower seeds, while the other group was restricted to their naturally available foods. DNA samples taken from all animals before and after the experiment, used molecular methods to determine telomere length.

It appears a full belly rejuvenates cells!

The DNA analysis revealed that telomere length at the end of the experiment was directly correlated with food availability.

Only the group that received surplus food had longer telomere lengths at the end of the study.

The animals restricted to naturally occurring food sources, on the other hand, were barely able to compensate for degrading telomeres.

The capability of dormice to elongate their own telomeres in normal body cells is very unusual. In other organisms, including humans, telomere elongation occurs only in germ cells (eggs and sperm) and tumor cells.

Somehow, edible dormice have managed to keep their cells "young" without developing cancer.

We studied the impact of hibernation and food supply on relative telomere length (RTL), an indicator for aging and somatic maintenance, in free-living edible dormice. Small hibernators such as dormice have ∼50% higher maximum longevity than non-hibernators. Increased longevity could theoretically be due to prolonged torpor directly slowing cellular damage and RTL shortening. However, although mitosis is arrested in mammals at low body temperatures, recent evidence points to accelerated RTL shortening during periodic re-warming (arousal) from torpor. Therefore, we hypothesized that these arousals during hibernation should have a negative effect on RTL. Here, we show that RTL was shortened in all animals over the course of ∼1 year, during which dormice hibernated for 7.5–11.4 months. The rate of periodic arousals, rather than the time spent euthermic during the hibernation season, was the best predictor of RTL shortening. This finding points to negative effects on RTL of the transition from low torpor to high euthermic body temperature and metabolic rate during arousals, possibly because of increased oxidative stress. The animals were, however, able to elongate their telomeres during the active season, when food availability was increased by supplemental feeding in a year of low natural food abundance. We conclude that in addition to their energetic costs, periodic arousals also lead to accelerated cellular damage in terms of RTL shortening. Although dormice are able to counteract and even over-compensate for the negative effects of hibernation, restoration of RTL appears to be energetically costly.

Franz Hölzl, Jessica S. Cornils, Steve Smith, Yoshan Moodley and Thomas Ruf was published in Journal of Experimental Biology. http://jeb.biologists.org/content/219/16/2469

About the University of Veterinary Medicine, Vienna
The University of Veterinary Medicine, Vienna in Austria is one of the leading academic and research institutions in the field of Veterinary Sciences in Europe. About 1,300 employees and 2,300 students work on the campus in the north of Vienna which also houses five university clinics and various research sites. Outside of Vienna the university operates Teaching and Research Farms. http://www.vetmeduni.ac.at

Scientific Contact:
Franz Hölzl
Research Institute of Wildlife Ecology
University of Veterinary Medicine Vienna (Vetmeduni Vienna)
T +43 1 25077-7273

Released by:
Georg Mair
Science Communication / Corporate Communications
University of Veterinary Medicine Vienna (Vetmeduni Vienna)
T +43 1 25077-1165 , georg.mair@vetmeduni.ac.at

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Sep 16, 2016   Fetal Timeline   Maternal Timeline   News   News Archive   

High food availability during summer time slows down cell aging in dormice — not hibernation.
Image Credit:
Vetmeduni Vienna.


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