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- Rollings, N., et al.
(författare)
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Age-related sex differences in body condition and telomere dynamics of red-sided garter snakes
- 2017
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Ingår i: Proceedings of the Royal Society B-Biological Sciences. - : The Royal Society. - 0962-8452 .- 1471-2954. ; 284:1852
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Tidskriftsartikel (refereegranskat)abstract
- Life-history strategies vary dramatically between the sexes, which may drive divergence in sex-specific senescence and mortality rates. Telomeres are tandem nucleotide repeats that protect the ends of chromosomes from erosion during cell division. Telomeres have been implicated in senescence and mortality because they tend to shorten with stress, growth and age. We investigated age-specific telomere length in female and male red-sided garter snakes, Thamnophis sirtalis parietalis. We hypothesized that age-specific telomere length would differ between males and females given their divergent reproductive strategies. Male garter snakes emerge from hibernation with high levels of corticosterone, which facilitates energy mobilization to fuel mate-searching, courtship and mating behaviours during a two to four week aphagous breeding period at the den site. Conversely, females remain at the dens for only about 4 days and seem to invest more energy in growth and cellular maintenance, as they usually reproduce biennially. As male investment in reproduction involves a yearly bout of physiologically stressful activities, while females prioritize self-maintenance, we predicted male snakes would experience more age-specific telomere loss than females. We investigated this prediction using skeletochronology to determine the ages of individuals and qPCR to determine telomere length in a cross-sectional study. For both sexes, telomere length was positively related to body condition. Telomere length decreased with age in male garter snakes, but remained stable in female snakes. There was no correlation between telomere length and growth in either sex, suggesting that our results are a consequence of divergent selection on life histories of males and females. Different selection on the sexes may be the physiological consequence of the sexual dimorphism and mating system dynamics displayed by this species.
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| 2. |
- Rollings, N., et al.
(författare)
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Sperm telomere length correlates with blood telomeres and body size in red-sided garter snakes, Thamnophis sirtalis parietalis
- 2020
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Ingår i: Journal of Zoology. - : Wiley. - 0952-8369 .- 1469-7998. ; 312:1, s. 21-31
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Tidskriftsartikel (refereegranskat)abstract
- Telomeres, tandem repeats of TTAGGG at the ends of chromosomes, are highly dynamic structures that shorten in response to a variety of factors, including organismal stress and tissue-specific growth rates. Cell turnover rates are frequently linked to their functions, resource availability and telomere dynamics. Using male red-sided garter snakes, Thamnophis sirtalis parietalis, as a model, we investigated the relationship between telomere length in sperm cells, blood cells telomere length and a growth proxy (age-adjusted body length and mass). This relationship is interesting because snakes exhibit indeterminate growth and because these garter snakes have a dissociated reproductive cycle where spermatogenesis occurs months prior to the mating season. In this study, we determined sperm telomere length (STL) and male age using qPCR and skeletochronology, respectively. Sperm telomere length correlated positively with snout-vent length (SVL) and with age-adjusted SVL as a proxy for growth rate (residuals of size against age regression, hereafter growth), but not with age. Although an individual's STL is correlated with blood telomere length (BTL), sperm telomeres are 60% longer than blood telomeres. In previous work, we have shown that BTL is shorter in older males and unrelated to SVL or any growth rate proxies. We hypothesized that STL is related to growth and SVL because growth and sperm production both occur during summer when resources are most abundant and stress lowest. This study is the first to compare telomere dynamics between cell types in a snake and supports growing evidence that telomere dynamics may be highly tissue-specific and driven by the life-history strategy of an organism.
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