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147 results for “Telomere Length”
Wing: A suitable non-lethal tissue type for repeatable and rapid telomere length estimates in bats
Telomeres are used increasingly in ecology and evolution as biomarkers for ageing and environmental stress, and are typically measured from DNA extracted from non-lethally sampled blood. However, obtaining blood is not always possible in field conditions and only limited amounts can be taken from small mammals, such as bats, which moreover lack nucleated red blood cells and hence yield relatively low amounts of DNA. As telomere length can vary within species according to age and tissue, it is important to determine which tissues serve best as a representation of the organism as a whole. Here, we investigated whether wing tissue biopsies, a rapid and relatively non-invasive tissue collection method, could serve as a proxy for other tissues when measuring relative telomere length (rTL) in the Egyptian fruit bat (Rousettus aegyptiacus). Telomeres were measured from blood, brain, heart, kidney, liver lung, muscle and wing, and multiple wing biopsies were taken from the same individuals to determine intra-individual repeatability of rTL measured by using qPCR. Wing rTL correlated with rTL estimates from most tissues apart from blood. Blood rTL was not significantly correlated with rTL from any other tissue. Blood and muscle rTL were significantly longer compared with other tissues, while lung displayed the shortest rTLs. Individual repeatability of rTL measures from wing tissue was high (>76%). Here we show the relationships between tissue telomere dynamics for the first time in a bat, and our results provide support for the use of wing tissue for rTL measurements.
Telomere length in relation to colour polymorphism across life stages in the tawny owl
<p>Abstract of the paper:<br> Telomere erosion has been proposed to be tightly associated with senescence, environmental stressors and life history trade-offs. How telomere dynamics vary across life stages and especially in relation to (heritable) phenotypic traits is still unclear. The tawny owl <em>Strix aluco</em> display a highly heritable melanin-based colour polymorphism, a grey and a brown morph, linked to several fitness traits including morph-specific telomere dynamics. As adults, brown tawny owls have shorter relative telomere length (RTL) and exhibit faster telomere shortening rate than grey owls. Here we test if these morph-specific telomere dynamics emerge already during growth, or if they are induced only in adult life through differential physiological costs associated with the life history of the morphs. We analysed RTL from 287 tawny owl offspring and 81 first breeding adults to evaluate at what life stage morph-specific patterns emerge. We found no differences in RTL between the two morphs during the nestling period nor at the first breeding attempt. Sex, brood size or size rank in the nest did not affect offspring RTL. Among first-breeders, females had shorter telomeres than males suggesting a sampling time dependent difference in reproductive costs between sexes, due to the prominent sex roles in tawny owls in the early nestling period. The probability to return to breed after the first breeding attempt was not affected by RTL, sex or colour morph. The lack of morph-specific difference in RTL among nestlings and first breeders suggests that previously observed morph-specific differences in RTL dynamics in adults emerge at the onset of the breeding career and is likely due to different physiological profiles and life-history strategies adopted by adults. We conclude that different telomere dynamics and senescence patterns among highly heritable phenotypes (colour morphs) are likely to be a result of differential costs of reproduction and self-maintenance.</p>
Data from: Telomere length reflects reproductive effort indicated by corticosterone levels in a long-lived seabird
Telomere length (TL) is a candidate biomarker of ageing and phenotypic quality, but little is known of the (physiological) causes of TL variation. We previously showed that individual common terns Sterna hirundo with high reproductive success had short telomeres independent of age, and this pattern was particularly strong in the longer telomeres of the within-individual TL distribution. To test whether this relation can be attributed to effects of reproductive effort, we investigated baseline corticosterone in relation to reproductive success (number of fledglings) and TL. In this context, we assume that variation in baseline corticosterone can be interpreted as index of energy expenditure and allostatic load. Males with higher corticosterone levels during incubation, compared between and within individuals, achieved higher reproductive success and had shorter telomeres. The effect on telomeres was more pronounced in corticosterone measured later in incubation and in the longer telomeres of the within-individual TL distribution. Female corticosterone level during incubation was neither related to reproductive success nor to TL. That we observed these effects only in males mirrors different parental roles during reproduction in the common tern, where males do most of the chick provisioning. The negative association between reproductive success and TL suggests individual differences in reproductive effort as reflected in, or mediated by, baseline corticosterone. We see this result as a promising step towards unravelling the physiological causes of variation in TL and the costs of reproduction.
Data from: Early-life telomere length predicts lifespan and lifetime reproductive success in a wild bird
Poor conditions during early development can initiate trade-offs that favour current survival at the expense of somatic maintenance and subsequently, future reproduction. However, the mechanisms that link early and late life-history are largely unknown. Recently it has been suggested that telomeres, the nucleoprotein structures at the terminal end of chromosomes, could link early-life conditions to lifespan and fitness. In wild purple-crowned fairy-wrens, we combined measurements of nestling telomere length (TL) with detailed life-history data to investigate whether early-life TL predicts fitness prospects. Our study differs from previous studies in the completeness of our fitness estimates in a highly philopatric population. The association between TL and survival was age-dependent with early-life TL having a positive effect on lifespan only among individuals that survived their first year. Early-life TL was not associated with the probability or age of gaining a breeding position. Interestingly, early-life TL was positively related to breeding duration, contribution to population growth and lifetime reproductive success because of their association with lifespan. Thus, early-life TL, which reflects growth, accumulated early-life stress and inherited TL, predicted fitness in birds that reached adulthood but not noticeably among fledglings. These findings suggest that a lack of investment in somatic maintenance during development particularly affects late life performance. This study demonstrates that factors in early-life are related to fitness prospects through lifespan, and suggests that the study of telomeres may provide insight into the underlying physiological mechanisms linking early- and late-life performance and trade-offs across a lifetime.
Data from: Extent and variability of interstitial telomeric sequences and their effects on estimates of telomere length
Telomeres often shorten with time, although this varies between tissues, individuals and species, and their length and/or rate of change may reflect fitness and rate of senescence. Measurement of telomeres is increasingly important to ecologists, yet the relative merits of different methods for estimating telomere length are not clear. In particular the extent to which interstitial telomere sequences (ITSs), telomere repeats located away from chromosomes ends, confound estimates of telomere length is unknown. Here we present a method to estimate the extent of ITS within a species and variation among individuals. We estimated the extent of ITS by comparing the amount of label hybridized to in-gel telomere restriction fragments (TRF) before and after the TRFs were denatured. This protocol produced robust and repeatable estimates of the extent of ITS in birds. In five species, the amount of ITS was substantial, ranging from 15% to 40% of total telomeric sequence DNA. In addition, the amount of ITS can vary significantly among individuals within a species. Including ITSs in telomere length calculations always underestimated telomere length because most ITSs are shorter than most telomeres. The magnitude of that error varies with telomere length and is larger for longer telomeres. Estimating telomere length using methods that incorporate ITSs, such as Southern blot TRF and quantitative PCR analyses reduces an investigator's power to detect difference in telomere dynamics between individuals or over time within an individual.
Data from: Is telomere length a molecular marker of past thermal stress in wild fish?
Telomeres protect eukaryotic chromosomes; variation in telomere length has been linked (primarily in homoeothermic animals) to variation in stress, cellular ageing and disease risk. Moreover, telomeres have been suggested to function as biomarker for quantifying past environmental stress, but studies in wild animals remain rare. Environmental stress, such as extreme environmental temperatures in poikilothermic animals, may result in oxidative stress that accelerates telomere attrition. However, growth, which may depend on temperature, can also contribute to telomere attrition. To test for associations between multitissue telomere length and past water temperature while accounting for the previous individual growth, we used quantitative PCR to analyse samples from 112 young-of-the-year brown trout from 10 natural rivers with average water temperature differences of up to 6°C (and an absolute maximum of 23°C). We found negative associations between relative telomere length (RTL) and both average river temperature and individual body size. We found no indication of RTL–temperature association differences among six tissues, but we did find indications for differences among the tissues for associations between RTL and body size; size trends, albeit nonsignificant in their differences, were strongest in muscle and weakest in fin. Although causal relationships among temperature, growth, oxidative stress, and cross-sectional telomere length remain largely unknown, our results indicate that telomere-length variation in a poikilothermic wild animal is associated with both past temperature and growth.
Data from: Telomere length is repeatable, shortens with age and reproductive success, and predicts remaining lifespan in a long-lived seabird
<p>Telomeres are protective caps at the end of chromosomes, and their length is positively correlated with individual health and lifespan across taxa. Longitudinal studies have provided mixed results regarding the within-individual repeatability of telomere length. While some studies suggest telomere length to be highly dynamic and sensitive to resource-demanding or stressful conditions, others suggest that between-individual differences are mostly present from birth and relatively little affected by the later environment. This dichotomy could arise from differences between species, but also from methodological issues. In our study, we used the highly reliable Terminal Restriction Fragment analysis method to measure telomeres over a 10-year period in adults of a long-lived seabird, the common tern (<i>Sterna hirundo</i>). Telomeres shortened with age within individuals. The individual repeatability of age-dependent telomere length was high (> 0.53), and independent of the measurement interval (i.e. 1 <i>vs.</i> 6 years). A small (R<sup>2</sup> = 0.01), but significant part of the between-individual variation in telomere length was, however, explained by the number of fledglings produced in the previous year, while reproduction in years prior to the previous year had no effect. We confirmed that age-dependent telomere length predicted an individual's remaining lifespan. Overall, our study suggests that the majority of between-individual variation in adult telomere length is consistent across adult life, and that a smaller part of the variation can be explained by dynamic factors, such as reproduction.</p>
Data from: Experimentally increased reproductive effort alters telomere length in the blue tit (Cyanistes caeruleus)
Telomeres have recently been suggested to play important role in ageing and are considered to be a reliable ageing biomarkers. The life history theory predicts that costs of reproduction should be expressed in terms of accelerated senescence, and some empirical studies do confirm such presumption. Thus, a link between reproductive effort and telomere dynamics should be anticipated. Recent studies have indeed demonstrated that reproduction may trigger telomere loss, but actual impact of reproductive effort has not received adequate attention in experimental studies. Here, we experimentally manipulated reproductive effort by increasing the brood size in the wild blue tit (Cyanistes caeruleus). We show that parents attending enlarged broods experienced larger yearly telomere decay in comparison to control birds attending unaltered broods. In addition, we demonstrate that the change in telomere length differs between sexes, but this effect was independent from our treatment. To our knowledge, this is the first experimental study in the wild revealing that telomere dynamics may be linked to reproductive effort. Thus, telomere shortening may constitute one of the potential proximate mechanisms mediating the costs of reproduction.
Data from: Harsh conditions during early development influence telomere length in an altricial passerine: links with oxidative stress and corticosteroids
Stress during early development can induce substantial long-term effects in organisms. In the case of birds, despite growth compensations, nestlings reared under harsh conditions typically show reduced survival chances in adulthood. It has been proposed that environmental early-life stressors could affect longevity via effects on telomere length, possibly mediated through oxidative stress. However, the link between these processes is not clear. In this study, we experimentally manipulated brood size in spotless starlings (Sturnus unicolor) to test the causal relationship between early stress, oxidative and corticosterone-mediated stress and telomere shortening. Our results show that experimentally enlarged brood sizes led to a reduction in morphometric development on nestlings, the effect being stronger for females than males. Additionally, basal corticosterone levels increased with increasing brood size in female nestlings. Neither plasma antioxidant status nor malondialdehyde levels (a marker of lipid peroxidation) were affected by experimental brood size, although the levels of a key intracellular antioxidant (glutathione) decreased with increasing brood size. We found that the treatment showed a quadratic effect on nestling telomere lengths, that were shortened either by increases or decreases of the original brood size. Our study provides experimental evidence for a link between developmental stress and telomere length, but does not support a direct causal link of this reduction with corticosterone or oxidative stress. We suggest that future studies should focus on how telomere length responds to additional markers of allostatic load.
Telomere lengths of great tit nestlings in Latvia (2018-2019)
<p>This study deals with telomere lengths of 15-day-old great tit nestlings in two habitats: an old-growth mature unmanaged coniferous forest and a young-managed coniferous forest in 2018 in SE Latvia. Survival of nestlings at day 15 also was measured. </p>
Early life growth and telomere length in wild boar piglets 2018
<p><span>Life history theory predicts a trade-off between growth rates and lifespan, which is reflected by telomere length, a biomarker of somatic state. We investigated the correlation between telomere</span><span> length and early life growth of wild boar piglets, <i>Sus scrofa, </i>kept under semi-natural conditions with</span><span> high food availability to examine our hypothesis that increased pre-and post-natal growth will lead to</span><span> telomere length attrition but that a high supply of nutrient may provide the possibility to compensate telomere loss via telomere repair mechanisms. As predicted, our data showed a clear negative correlation between birth body mass and initial telomere length: heavier neonates had shorter telomeres at birth, and we did not find an influence of the mother on initial telomere length. Body mass at birth correlated with body mass later in life and post-natal growth rate did not affect telomere length. We observed an increase in telomere length during postnatal development, suggesting that high food availability allowed piglets to invest into both, growth and telomere restoration. The increase in telomere length over the duration of the study was not accompanied by telomerase activity, thus telomere elongation was either caused by alternative mechanisms or by short pulses of telomerase activity, that we missed. Taken together, this study suggests a trade-off between investment into growth and telomere maintenance even before birth and the possibility to compensate telomere attrition during growth under high amounts of available energy.</span></p>
Data for: Telomere length is highly repeatable and shorter in individuals with more elaborate sexual ornamentation in a short-lived passerine
<p>Quantifying an individual's state as fitness proxy has proven challenging, but accumulating evidence suggests that telomere length and attrition may indicate individual somatic state and success at self-maintenance, respectively. Sexual ornamentation is also thought to signal phenotypic quality, but links between telomeres and sexual ornamentation have been little explored. To address this issue, we examined whether telomere length and dynamics are predicted by the expression of a sexually selected ornament, the length of the outermost tail feathers (streamers), using longitudinal data from a population of European barn swallows (Hirundo rustica). In 139 adult individuals, each measured twice, we further assessed associations of telomere length with age, sex, breeding status and survival. Telomere length showed high individual repeatability (R = 0.97) across years while shortening with age in both sexes. Telomere length and dynamics were not significantly associated with survival to the next year, remaining lifespan, or reproduction status (comparing breeding and non-breeding yearlings). Tail streamer length, a sexually selected trait in barn swallows, was negatively associated with telomere length, independent of sex. Thus, telomere length may reflect the costs of carrying an elaborated sexual ornament, although ornament size did not significantly predict telomere shortening. In conclusion, telomere length in adult barn swallows is a highly consistent trait that shows a negative relationship with sexual ornamentation, suggesting a trade-off between sexual ornamentation and telomere length.</p>
Data for: Heritability and parental effects in telomere length in a color polymorphic long-lived bird
<p>Telomere length, an indicator of senescence, has been shown to be heritable but can also be affected by environmental factors, like parental effects. Investigating heritability as well as parental effects and rearing environment can help us to understand the factors affecting offspring telomeres. Moreover, how phenotypic parental traits linked with fitness can impact offspring telomere length is still unclear. A phenotypic marker closely associated with physiological traits and fitness is melanin-based color polymorphism, which in tawny owl (<em>Strix aluco</em>) is highly heritable and strongly associated with adult telomere shortening and survival. We studied narrow-sense heritability (h<sup>2</sup>) of telomere length (RTL), as well as the impact of parental age and color morph and their interaction on offspring telomere length. Offspring RTL at fledging was strongly positively correlated with both mother and father RTL at breeding. Offspring RTL was also negatively associated with father age, suggesting that older fathers sired offspring with shorter telomeres. Parental color morph did not explain offspring telomere length and there were no interactive effects of parental morph and age, despite previously documented morph-specific senescence patterns. Our results suggest that telomere length is highly heritable and affected by paternal age, but not related to color polymorphism. This suggests that either morph-specific telomere shortening as adult does not result in significantly shorter telomeres in their gametes, or that parents compensate morph-specific senescence via parental care. Morph-specific patterns of telomere dynamics in polymorphic species may thus emerge from different life-history strategies adopted in adulthood.</p>
Telomere length correlates with physiological and behavioural responses of a long-lived seabird to an ecologically-relevant challenge
<p>Determinants of individual variation in reallocation of limited resources towards self-maintenance versus reproduction are not well known. We tested the hypothesis that individual heterogeneity in long-term "somatic state" a) explains variation in endocrine and behavioural responses to environmental challenges, and b) is associated with variation in strategies for allocating to self-maintenance versus reproduction. We used relative telomere length as an indicator of somatic state and experimentally generated an abrupt short-term reduction of food availability (withdrawal of food supplementation) for free-living seabirds (Black-legged kittiwakes, Rissa tridactyla). Incubating male kittiwakes responded to withdrawal by increasing circulating corticosterone and losing more weight compared to continuously supplemented controls. Males with longer telomeres increased time in directed travel regardless of treatment, while experiencing smaller increases in corticosterone. Males with longer telomeres fledged more chicks in the control group and tended to be more likely to return regardless of treatment. This study supports the hypothesis that somatic state can explain variation in short-term physiological and behavioural responses to challenges, and longer-term consequences for fitness. Male kittiwakes with longer telomeres appear to have prioritized investment in self over investment in offspring under challenging conditions.</p>
Decline in telomere length with increasing age across non‐human vertebrates: a meta‐analysis
<p>The prediction that telomere length (TL) shortens with increasing age is a major element in considering the role of telomeres as a key player in evolution. While telomere attrition is found in humans both <i>in vitro</i> and <i>in vivo</i>, the increasing number of studies reporting diverse age-specific patterns of TL challenges the hypothesis of a universal decline of TL with increasing age. Here we performed a meta-analysis to estimate the relationship between TL and age across 175 estimates encompassing 98 species of vertebrates. We found that, on average, TL does decline with increasing age during adulthood. However, this decline was weak and variable across vertebrate classes, and we also found evidence for a publication bias that might weaken our current evidence of decreasing TL with increasing age. We found no evidence for a faster decline in TL with increasing age when considering the juvenile stage (from birth to age at first reproduction) compared to the adult stage. Heterogeneity in TL ageing rates was explained by the method used to measure telomeres: detectable TL declines with increasing age were found only among studies using TRF with in-gel hybridisation and qFISH methods, but not in studies using qPCR and Southern blot-based TRF methods. While we confirmed that TL declines with increasing age in most adult vertebrates, our results identify an influence of telomere measurement methodology, which highlights the need to examine more thoroughly the effect of the method of measurement on TL estimates.</p>
Data from: High heritability of telomere length and low heritability of telomere shortening in wild birds
<p>Telomere length and telomere shortening predict survival in many organisms. This raises the question of the contribution of genetic and environmental effects to variation in these traits, which is still poorly known, particularly for telomere shortening. We used experimental (cross-fostering) and statistical (quantitative genetic 'animal' models) means to disentangle and estimate genetic and environmental contributions to telomere length variation in pedigreed free-living jackdaws (<i>Corvus monedula</i>). Telomere length was measured twice in nestlings, at ages 4 (n=715) and 29 days (n=474), using TRF-analysis, adapted to exclude interstitial telomeric sequences. Telomere length shortened significantly over the nestling period (10.4±0.3 bp/day) and was highly phenotypically (<i>r<sub>P</sub></i>=0.95±0.01) and genetically (<i>r<sub>G</sub></i>>0.99±0.01) correlated within individuals. Additive genetic effects explained a major part of telomere length variation among individuals, with its heritability estimated at <i>h<sup>2</sup></i>=0.74 on average. We note that TRF-based studies reported higher heritabilities than qPCR-based studies, and we discuss possible explanations. Parent-offspring regressions yielded similar heritability estimates for mothers and fathers when accounting for changes in paternal telomere length over life. Year effects explained a small but significant part of telomere length variation. Heritable variation for telomere shortening was low (<i>h<sup>2</sup></i>=0.09±0.11). The difference in heritability between telomere length (high) and telomere shortening (low) agrees with evolutionary theory, in that telomere shortening has stronger fitness consequences in this population. Despite the high heritability of telomere length, its evolvability, which scales the additive genetic variance by mean telomere length, was on average 0.48%. Hence evolutionary change of telomere length due to selection is likely to be slow.</p>
Experimental ectoparasite removal has a sex-specific effect on nestling telomere length
<p>Parasites are a strong selective force that can influence fitness-related traits. The length of chromosome-capping telomeres can be used to assess the long-term costs of parasitism, as telomere loss accelerates in response to environmental stressors and often precedes poorer survival prospects. Here, we explored the sex-specific effects of ectoparasite removal on morphology and telomere length in nestling tree swallows (<em>Tachycineta bicolor</em>). To do so, we experimentally removed blowfly (<em>Protocalliphora</em> spp.) larvae from nests using Permethrin, a broad-spectrum insecticide. Compared to water-treated controls, insecticide treatment of nests had a sex-biased effect on blood telomere length: ectoparasite removal resulted in significantly longer telomeres in males but not females. While this treatment did not influence nestling body mass, it was associated with reduced feather development regardless of sex. This may reflect a relaxed pressure to fledge quickly in the absence of parasites, or alternatively, could be a negative side effect of permethrin on morphology. Exploring robust sex-specific telomere dynamics in response to early-life environmental pressures such as parasitism will shed light on sexual dimorphism in adult life histories and ageing.</p>
Data for: When does early-life telomere length predict survival? A case study and meta-analysis
<p>Suboptimal conditions during development can shorten telomeres, the protective DNA caps on the end of chromosomes. Shorter early-life telomere length (TL) can indicate reduced somatic maintenance, leading to lower survival and shorter lifespan. However, despite some clear evidence, not all studies show a relationship between early-life TL and survival or lifespan, which may be due to differences in biology or study design (e.g., survival period measured). In superb fairy-wrens (<em>Malurus cyaneus</em>), we assessed whether early-life TL predicts mortality across different life-history stages (fledgling, juvenile, adult). However, in contrast to a similar study on a congener, early-life TL did not predict mortality across any life stage in this species. We then performed a meta-analysis including 32 effect sizes from 23 studies (15 birds and 3 mammals) to quantify the effect of early-life TL on mortality whilst taking into consideration potential sources of biological and methodological variation. Overall, the effect of early-life TL on mortality was significant, corresponding to a 15% reduction in mortality risk with each standard deviation increase in TL. However, the effect became weaker when correcting for publication bias. Contrary to our predictions, there was no evidence that effects of early-life TL on mortality varied with species lifespan or the period over which survival was measured. However, negative effects of early-life TL on mortality risk were pervasive throughout life. These results imply that effects of early-life TL on mortality are more likely context-dependent rather than age-dependent, although substantial power and publication bias issues highlight the need for more research.</p>
Aerobic Exercise and Telomere Length in Patients With Heart Failure.
ClinicalTrials.gov study NCT03856736. IPD Sharing: UNDECIDED. Countries: 1. Publications: 1.
Telomere Length and Other Parameters of Telomere Dysfunction in PSC and Colitis
ClinicalTrials.gov study NCT02247622. IPD Sharing: Not stated. Countries: 1. Publications: 1.
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