Abstract
Telomere shortening is thought to be an important biomarker for life history traits such as lifespan and aging, and can be indicative of genome integrity, survival probability and the risk of cancer development. In humans and other animals, telomeres almost always shorten with age, with more rapid telomere attrition in short-lived species. Here, we show that in the edible dormouse (Glis glis) telomere length significantly increases from an age of 6 to an age of 9 years. While this finding could be due to higher survival of individuals with longer telomeres, we also found, using longitudinal measurements, a positive effect of age on the rate of telomere elongation within older individuals. To our knowledge, no previous study has reported such an effect of age on telomere lengthening. We attribute this exceptional pattern to the peculiar life-history of this species, which skips reproduction in years with low food availability. Further, we show that this “sit tight” strategy in the timing of reproduction is associated with an increasing likelihood for an individual to reproduce as it ages. As reproduction could facilitate telomere attrition, this life-history strategy may have led to the evolution of increased somatic maintenance and telomere elongation with increasing age.
Highlights
Telomeres, which in vertebrates contain many tandem repeats of the sequence motif 5′-TTAGGG-3′1, are the endcaps of chromosomes which prevent, together with telomere associated proteins, the degradation of coding DNA sequences
The high longevity of edible dormice is partly due to their skipping of reproduction in years of tree-seeding failure, which leads to a large variation in yearly reproductive effort[19]
relative telomere length (RTL) was not affected by time of the year, sex, body mass or reproductive activity/capability at the time of sampling
Summary
Telomeres, which in vertebrates contain many tandem repeats of the sequence motif 5′-TTAGGG-3′1, are the endcaps of chromosomes which prevent, together with telomere associated proteins (the sheltering complex), the degradation of coding DNA sequences. Telomeres are shortened with every cell division – due to the end replication problem in mitosis[2,3] In addition to this shortening during cell proliferation, oxidative stress has a strong effect on telomere erosion[4]. In two species of hibernating dormice, telomere length is shortened over the hibernation season during bouts of rewarming[12,13,14], which are associated with increased oxidative stress[15,16]. For adult edible dormice it was shown that telomeres are restored and even increase in length during the summer active season[12,14] This capability of edible dormice to re-elongate telomeres runs contrary to the accepted process of progressive, systematic shortening of telomeres with age and raises questions about the long-term balance between telomere attrition and repair. We expected that reproduction may exacerbate telomere attrition and that, vice versa, high levels of telomere maintenance should be reflected by slow or absent reproductive senescence
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