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1. Parental age does not influence offspring telomeres during early life in common gulls (Larus canus)

   https://doi.org/DOI: 10.1111/mec.15905  

   Sepp, T. ; Meitern, R ; Heidinger, B. ; Noreikiene, K. ; Rattiste, K. ; Horak, P. ; Saks, L. ; Kittilson, J. ; Urvik, J. ; Giraudeau, M. ( January 2021 , Molecular ecology)

   null (Ed.)

   Parental age can affect offspring telomere length through heritable and epigenetic-like effects, but at what stage during development these effects are established is not well known. To address this, we conducted a cross-fostering experiment in common gulls (Larus canus) that enabled us distinguish between pre-and post-natal parental age effects on offspring telomere length. Whole clutches were exchanged after clutch completion within and between parental age classes (young and old) and blood samples were collected from chicks at hatching and during the fastest growth phase (11 days later) to measure telomeres. Neither the ages of the natal nor the foster parents predicted the telomere length or the change in telomere lengths of their chicks. Telomere length (TL) was repeatable within chicks, but increased across development (repeatability = 0.55, intraclass correlation coefficient within sampling events 0.934). Telomere length and the change in telomere length were not predicted by post-natal growth rate. Taken together, these findings suggest that in common gulls, telomere length during early life is not influenced by parental age or growth rate, which may indicate that protective mechanisms buffer telomeres from external conditions during development in this relatively long-lived species. 

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2. The environmental and genetic determinants of chick telomere length in Tree Swallows ( Tachycineta bicolor )

   https://doi.org/10.1002/ece3.5386  

   Belmaker, Amos ; Hallinger, Kelly K. ; Glynn, Rebbeca A. ; Winkler, David W. ; Haussmann, Mark F. ( July 2019 , Ecology and Evolution)

   Conditions during early life can have dramatic effects on adult characteristics and fitness. However, we still know little about the mechanisms that mediate these relationships. Telomere shortening is one possibility. Telomeres are long sequences of DNA that protect the ends of chromosomes. They shorten naturally throughout an individual's life, and individuals with short telomeres tend to have poorer health and reduced survival. Given this connection between telomere length (TL) and fitness, natural selection should favor individuals that are able to retain longer telomeres for a greater portion of their lives. However, the ability of natural selection to act on TL depends on the extent to which genetic and environmental factors influence TL. In this study, we experimentally enlarged broods of Tree Swallows (Tachycineta bicolor) to test the effects of demanding early‐life conditions on TL, while simultaneously cross‐fostering chicks to estimate heritable genetic influences on TL. In addition, we estimated the effects of parental age and chick sex on chick TL. We found that TL is highly heritable in Tree Swallow chicks, and that the maternal genetic basis for TL is stronger than is the paternal genetic basis. In contrast, the experimental manipulation of brood size had only a weak effect on chick TL, suggesting that the role of environmental factors in influencing TL early in life is limited. There was no effect of chick sex or parental age on chick TL. While these results are consistent with those reported in some studies, they are in conflict with others. These disparate conclusions might be attributable to the inherent complexity of telomere dynamics playing out differently in different populations or to study‐specific variation in the age at which subjects were measured.

    

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3. Sperm telomere length correlates with blood telomeres and body size in red‐sided garter snakes, Thamnophis sirtalis parietalis

   https://doi.org/10.1111/jzo.12789  

   Rollings, N. ; Waye, H_L ; Krohmer, R_W ; Uhrig, E_J ; Mason, R_T ; Olsson, M. ; Whittington, C_M ; Friesen, C_R ( May 2020 , Journal of Zoology)

   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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4. The telomere regulatory gene POT1 responds to stress and predicts performance in nature: Implications for telomeres and life history evolution

   https://doi.org/10.1111/mec.16237  

   Wolf, Sarah_E ; Sanders, Tiana_L ; Beltran, Sol_E ; Rosvall, Kimberly_A ( November 2021 , Molecular Ecology)

   Telomeres are emerging as correlates of fitness‐related traits and may be important mediators of ecologically relevant variation in life history strategies. Growing evidence suggests that telomere dynamics can be more predictive of performance than length itself, but very little work considers how telomere regulatory mechanisms respond to environmental challenges or influence performance in nature. Here, we combine observational and experimental data sets from free‐living tree swallows (Tachycineta bicolor) to assess how performance is predicted by the telomere regulatory gene POT1, which encodes a shelterin protein that sterically blocks telomerase from repairing the telomere. First, we show that lower POT1 gene expression in the blood was associated with higher female quality, that is, earlier breeding and heavier body mass. We next challenged mothers with an immune stressor (lipopolysaccharide injection) that led to “sickness” in mothers and 24 h of food restriction in their offspring. While POT1 did not respond to maternal injection, females with lower constitutive POT1 gene expression were better able to maintain feeding rates following treatment. Maternal injection also generated a 1‐day stressor for chicks, which responded with lower POT1 gene expression and elongated telomeres. Other putatively stress‐responsive mechanisms (i.e., glucocorticoids, antioxidants) showed marginal responses in stress‐exposed chicks. Model comparisons indicated that POT1 mRNA abundance was a largely better predictor of performance than telomere dynamics, indicating that telomere regulators may be powerful modulators of variation in life history strategies.

    

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5. Telomere length is longer following diapause in two solitary bee species

   https://doi.org/10.1038/s41598-024-61613-2  

   Grula, Courtney C. ; Rinehart, Joshua D. ; Anacleto, Angelo ; Kittilson, Jeffrey D. ; Heidinger, Britt J. ; Greenlee, Kendra J. ; Rinehart, Joseph P. ; Bowsher, Julia H. ( May 2024 , Scientific Reports)

   The mechanisms that underlie senescence are not well understood in insects. Telomeres are conserved repetitive sequences at chromosome ends that protect DNA during replication. In many vertebrates, telomeres shorten during cell division and in response to stress and are often used as a cellular marker of senescence. However, little is known about telomere dynamics across the lifespan in invertebrates. We measured telomere length in larvae, prepupae, pupae, and adults of two species of solitary bees,Osmia lignariaandMegachile rotundata. Contrary to our predictions, telomere length was longer in later developmental stages in bothO. lignariaandM. rotundata.Longer telomeres occurred after emergence from diapause, which is a physiological state with increased tolerance to stress. InO. lignaria, telomeres were longer in adults when they emerged following diapause. InM. rotundata, telomeres were longer in the pupal stage and subsequent adult stage, which occurs after prepupal diapause. In both species, telomere length did not change during the 8 months of diapause. Telomere length did not differ by mass similarly across species or sex. We also did not see a difference in telomere length after adultO. lignariawere exposed to a nutritional stress, nor did length change during their adult lifespan. Taken together, these results suggest that telomere dynamics in solitary bees differ from what is commonly reported in vertebrates and suggest that insect diapause may influence telomere dynamics.

    

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