Telomere Length Research Articles

Deciphering the bidirectional impact of leukocyte telomere length on multiple sclerosis progression: A Mendelian randomization study.

Observational studies have suggested a link between leukocyte telomere length (LTL) and multiple sclerosis (MS) progression, but the causal relationship remains uncertain. This study investigates the causal association between LTL and MS progression using a bidirectional two-sample Mendelian randomization (MR) approach. We analyzed genome-wide association summary statistics data from 472,174 individuals for LTL and 12,584 MS patients for disease progression. The primary method was the inverse variance weighted (IVW) approach, supported by sensitivity analyses to ensure robustness. The forward analysis revealed a significant positive causal relationship between LTL and MS progression (β = 0.107, 95 % CI = 0.006 to 0.209, P = 0.037). Conversely, the reverse analysis indicated a negative causal relationship (β = -0.010, 95 % CI = -0.020 to -0.001, P = 0.037). No heterogeneity or horizontal pleiotropy was found, and the sensitivity analyses confirmed consistent results. These findings suggest that telomere dynamics play a complex role in MS progression and highlight their potential as therapeutic targets. Further research is essential to uncover the biological mechanisms underlying the influence of telomeres on MS progression.

Oral intake of degalactosylated whey protein increases peripheral blood telomere length in young and aged mice

In order to elucidate novel actions of degalactosylated whey protein (D-WP) in comparison with intact whey protein (WP), the effects of oral intake of D-WP on peripheral blood telomere length and telomerase were examined in young and aged mice. In young mice, peripheral blood telomere length was significantly elongated following oral intake of D-WP for 4 weeks. mRNA expression of both telomerase reverse transcriptase (TERT) and telomerase RNA component (TERC) was significantly increased in the peripheral blood following oral intake of D-WP for 4 weeks. In aged mice, peripheral blood telomere length was significantly decreased as compared with that of young mice, and significantly restored to the level of young mice drinking water by the oral intake of D-WP for 4 weeks. The mRNA expression of peripheral blood TERT and TERC mRNA in aged mice significantly decreased as compared with the level in young mice drinking water, and was significantly restored to the level of expression of young mice drinking water by oral intake of D-WP for 4 weeks. These results suggest that D-WP, but not WP, potently increases peripheral blood telomere length accompanied by increased mRNA expression of TERT and TERC in both young and aged mice.

Telomere length and telomerase activity in men and non-pregnant women with and without metabolic syndrome: a systematic review and bootstrapped meta-analysis.

We performed a systematic review and meta-analysisto examine the associations between telomere length and telomerase activity in subjects with and without metabolic syndrome (MetS). The meta-analysis protocol was registered in the PROSPERO database. The PubMed, Embase, Cochrane Library, and LILACS databases were searched for studies reporting telomere length or telomerase activity in adult men and non-pregnant women with and without MetS. The risk of bias was assessed with the Newcastle-Ottawa Scale. Random effects and inverse variance methods were used to meta-analyze associations. We conducted a bootstrapped analysis to test the accuracy of clinical results. Five studies reported telomere length and two studies telomerase activity. There was no significant difference in telomere length (standardized mean difference [SMD]: 0.10, 95% confidence interval [CI]: -0.07, 0.28, I 2: 54%), between subjects of similar age (mean difference: 2.68, 95%CI: -0.04, 5.40 years) with and without the MetS. Subjects with MetS displayed significantly higher body mass index, triglycerides, and blood pressure, and lower HDL-cholesterol values than subjects without the syndrome. A bootstrapping mediation analysis of telomere length confirmed the clinical results. There was no significant difference in telomerase activity (SMD: 1.19, 95% CI -0.17, 2.55, I 2: 93%) between subjects with and without the MetS. There were no significant differences of telomere length and telomerase activity in patients with MetS and subjects of similar age without the syndrome. The online version contains supplementary material available at 10.1007/s40200-024-01513-4.

Telomere length sensitive regulation of interleukin receptor 1 type 1 (IL1R1) by the shelterin protein TRF2 modulates immune signalling in the tumour microenvironment

Telomeres are crucial for cancer progression. Immune signalling in the tumour microenvironment has been shown to be very important in cancer prognosis. However, the mechanisms by which telomeres might affect tumour immune response remain poorly understood. Here, we observed that interleukin-1 signalling is telomere-length dependent in cancer cells. Mechanistically, non-telomeric TRF2 (telomeric repeat binding factor 2) binding at the IL-1-receptor type-1 (IL1R1) promoter was found to be affected by telomere length. Enhanced TRF2 binding at the IL1R1 promoter in cells with short telomeres directly recruited the histone-acetyl-transferase (HAT) p300, and consequent H3K27 acetylation activated IL1R1. This altered NF-kappa B signalling and affected downstream cytokines like IL6, IL8, and TNF. Further, IL1R1 expression was telomere-sensitive in triple-negative breast cancer (TNBC) clinical samples. Infiltration of tumour-associated macrophages (TAM) was also sensitive to the length of tumour cell telomeres and highly correlated with IL1R1 expression. The use of both IL1 Receptor antagonist (IL1RA) and IL1R1 targeting ligands could abrogate M2 macrophage infiltration in TNBC tumour organoids. In summary, using TNBC cancer tissue (>90 patients), tumour-derived organoids, cancer cells, and xenograft tumours with either long or short telomeres, we uncovered a heretofore undeciphered function of telomeres in modulating IL1 signalling and tumour immunity.

From cells to recapture rates: responses and recovery of a wild fish after an experimental exposure to a widely used herbicide.

Freshwater environments are biodiversity hotspots under multiple pressures, including pesticide exposure. S-metolachlor, a widely used herbicide, can induce genotoxic, cytotoxic and physiological effects in captive fish, but we have a limited understanding of the effects of exposure to S-metolachlor in free-living vertebrates. We carried out an original field experiment using integrative approaches across biological levels and temporal scales. The implantation of slow-release implants, an approach to mimic increasing exposure to S-metolachlor of wildlife in realistic multistress conditions, was coupled to a capture-mark-recapture monitoring of bullheads (Cottus perifretum) living in an agriculturally impacted stream. Thanks to our long-term monitoring programme, we evidenced high levels of metolachlor and its metabolites (metolachlor ESA and metolachlor OXA) in water bodies with strong monthly variations. S-metolachlor levels did not differ between treated and control fish and were moderate in bullhead tissues, likely because of xenobiotic metabolism and excretion. S-metolachlor exposure increased erythrocyte abnormalities and the neutrophil/lymphocyte (N/L) ratios. These cellular and physiological damages were observed at 2weeks, but not at 3months after the manipulation. This suggests a recovery, likely owing to cell turnover. We also found an increase of body mass of treated fish compared to control fish, and this mass gain persisted at 3months, suggesting obesogenic effects of S-metolachlor. Antioxidant levels, telomere length and recapture rate were not affected by the experimental treatment. In conclusion, we provide evidence for transient and specific cellular alterations induced by low concentrations of S-metolachlor and long-term mass gain in a wild vertebrate. This study paves the way for integrative field experiments to better understand the impacts of pollutants on fish populations.

Telomere length sensitive regulation of interleukin receptor 1 type 1 (IL1R1) by the shelterin protein TRF2 modulates immune signalling in the tumour microenvironment.

Telomeres are crucial for cancer progression. Immune signalling in the tumour microenvironment has been shown to be very important in cancer prognosis. However, the mechanisms by which telomeres might affect tumour immune response remain poorly understood. Here, we observed that interleukin-1 signalling is telomere-length dependent in cancer cells. Mechanistically, non-telomeric TRF2 (telomeric repeat binding factor 2) binding at the IL-1-receptor type-1 (IL1R1) promoter was found to be affected by telomere length. Enhanced TRF2 binding at the IL1R1 promoter in cells with short telomeres directly recruited the histone-acetyl-transferase (HAT) p300, and consequent H3K27 acetylation activated IL1R1. This altered NF-kappa B signalling and affected downstream cytokines like IL6, IL8, and TNF. Further, IL1R1 expression was telomere-sensitive in triple-negative breast cancer (TNBC) clinical samples. Infiltration of tumour-associated macrophages (TAM) was also sensitive to the length of tumour cell telomeres and highly correlated with IL1R1 expression. The use of both IL1 Receptor antagonist (IL1RA) and IL1R1 targeting ligands could abrogate M2 macrophage infiltration in TNBC tumour organoids. In summary, using TNBC cancer tissue (>90 patients), tumour-derived organoids, cancer cells, and xenograft tumours with either long or short telomeres, we uncovered a heretofore undeciphered function of telomeres in modulating IL1 signalling and tumour immunity.

The Role of Leukocyte Telomere Length in Cognitive Function, Symptom Severity, and Sdg-Related Health Goals Among Batak Schizophrenia Patients

Objective: To assess the relationship between leukocyte telomere length, cognitive function, and symptom severity in Batak tribe schizophrenia patients, with a focus on telomere length as a potential biomarker for disease progression and its relevance to Sustainable Development Goal (SDG) 3: Good Health and Well-being. Theoretical Framework: This study builds on findings linking leukocyte telomere shortening to accelerated aging, cognitive decline, and increased risks of neurodegenerative diseases and cancer. These connections underscore the importance of telomere length as a marker of symptom severity in schizophrenia and its alignment with global health objectives under the SDGs. Method: A 6-month cross-sectional study design with numerical correlation tests was used from January to June 2023. Eighty-five patients from the Batak tribe diagnosed with schizophrenia were recruited from Regional Mental Hospital Prof. Dr. M. Ildrem Medan, and telomere length analysis was conducted at Prodia Private Clinical Laboratory in Medan. Results and Discussion: The sample included 85 patients, mostly male (80%) with a mean age of 30.38 years (SD: 3.2). Cognitive function showed a mean MoCA-Ina score of 17.33 (SD: 5.4), and symptom severity showed a mean PANSS score of 48.87 (SD: 9.73). Leukocyte telomere length ratios were 0.92 (SD: 0.04) for β-globin T/S and 0.99 (SD: 0.05) for B4AU T/S. No significant link was found between telomere length and cognitive function (p>0.05), but shorter telomeres correlated with more severe symptoms (β-globin T/S: p=0.034, r=-0.23; B4AU T/S: p=0.037, r=-0.227). Research Implications: Findings indicate that leukocyte telomere length could serve as a biomarker for schizophrenia symptom severity, offering valuable insights for disease progression and contributing to health monitoring strategies aligned with SDG 3. Originality/Value: By focusing on the Batak tribe, this study highlights telomere length as a biomarker for prognosis and underscores the importance of diverse population studies to achieve SDG-related health outcomes.

Lipid Profiles, Telomere Length, and the Risk of Malignant Tumors: A Mendelian Randomization and Mediation Analysis.

Background/Objectives: The relationship between lipid profiles, telomere length (TL), and cancer risk remains unclear. Methods: This study employed two-sample Mendelian randomization (MR) with mediation analysis to investigate their causal relationships, examining lipid profiles as exposure, TL as mediator, and nine cancer types as outcomes. We conducted our analysis using two-stage least squares (2SLS) regression integrated with inverse variance weighted (IVW) methods to address potential endogeneity and strengthen our causal inference. Results: we found that unfavorable lipid profiles were causally linked to increased TL (p < 0.05). TL showed positive causal associations with lung and hematologic cancers (OR > 1, p < 0.05). Direct associations were observed between total and low-density lipoprotein (LDL) cholesterol and gastric cancer (OR < 1, p < 0.05), and between remnant cholesterol and colorectal cancer (OR > 1, p < 0.05). Mediation analysis revealed TL as a significant mediator in the pathway from lipid profiles to cancer development (p < 0.05). No horizontal pleiotropy was detected. Conclusions: Our findings suggest that lipid metabolism disorders may influence cancer development through telomere regulation, particularly in lung and hematologic cancers. This emphasizes the importance of lipid management in cancer prevention and treatment, especially for these cancer types.

Biological Aging and Venous Thromboembolism: A Review of Telomeres and Beyond.

Although venous thromboembolism (VTE) is the third most common cardiovascular disease, and the risk of VTE increases sharply with advancing age, approximately 40% of VTE cases are currently classified as unprovoked, highlighting the importance of risk factor research. While chronological aging is associated with the risk of VTE, the association with biological aging remains unclear. Biological aging is highly complex, influenced by several dysregulated cellular and biochemical mechanisms. In the last decade, advancements in omics methodologies provided insights into the molecular complexity of biological aging. Techniques such as high-throughput genomics, epigenomics, transcriptomics, proteomics, and metabolomics analyses identified and quantified numerous epigenetic markers, transcripts, proteins, and metabolites. These methods have also revealed the molecular alterations organisms undergo as they age. Despite the progress, there is still a lack of consensus regarding the methods for assessing and validating these biomarkers, and their application lacks standardization. This review gives an overview of biomarkers of biological aging, including telomere length, and their potential role for VTE. Furthermore, we critically examine the advantages and disadvantages of the proposed methods and discuss possible future directions for investigating biological aging in VTE.

A novel method for telomere length detection in fission yeast.

Fission yeast is the ideal model organism for studying telomere maintenance in higher eukaryotes. Telomere length has been directly correlated with life expectancy and the onset of aging-related diseases in mammals. In this study, we developed a novel simple, and reproducible method to measure the telomere length, by investigating the effect of caffeine and cisplatin on the telomere length in fission yeast. Hydroxyurea-synchronized fission yeast cells were exposed to 62 µM cisplatin and 8.67mM caffeine treatments for 2 h, then their telomere lengths were evaluated with two different methods. First, the quantitative polymerase chain reaction (qPCR) assay was used as a confirmative method, where telomere length was determined relative to a single-copy gene in the genome. Second, the newly developed method standard polymerase chain reaction (PCR)/ImageJ assay assessed the telomere length based on the amplified PCR band intensity using a set of telomere primers, reflecting telomeric sequence availability in the genome. Both methods show a significant decrease and a notable telomere lengthening in response to cisplatin and caffeine treatments, respectively. The finding supports the accuracy and productivity of the standard PCR/ImageJ assay as it can serve as a quick screening tool to study the effect of suspected chemotherapeutic and antiaging drugs on telomere length in fission yeast.

Correction: Micronutrient intake and telomere length: findings from the UK Biobank

Correction: Micronutrient intake and telomere length: findings from the UK Biobank

Impact of telomere length for risk assessment and prognosis in papillary thyroid cancer depending on the clinicopathological features.

. Despite the establishment of a link between telomere status and carcinogenesis, lack of a consensus in the cancer specific pattern of telomere length has a severe impact on the use of relative telomere length (RTL) in cancer diagnosis. The disparity in assessing the relationship between telomere length and cancer risk is complex and may vary as it is influenced by other factors. The objective of this study is to thoroughly examine the intricate relationship between telomere length and cancer incidence in Papillary Thyroid Cancer (PTC) depending on the tumor type, stage, patients' sex and age. Therefore, the current study is focused on the association of RTL in PTC patients with different clinicopathological characteristics and compared with controls to determine the risk of PTC and expected survival time after surgery. . This study included 126 patients with PTC and 80 controls. RTL in thyroid tissues was measured using quantitative (q) PCR. Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated using logistic regression analysis. Kaplan-Meier and Cox regression were used to analyze postsurgical outcomes. . The RTL of patients was significantly shorter than that of controls. A short RTL was significantly correlated with an elevated risk of PTC in patients aged ≥ 55 years, female sex, classic subtype, and tumor size > 2cm. A short RTL did not affect the overall survival of patients with PTC; however, it was associated with poor survival in patients with tumor size > 2cm and tumor invasion. . This unique study combines the use of RTL with various clinicopathological features of patients with PTC. In conclusion, RTL is a promising tumor marker that correlates with the clinical characteristics of patients with PTC. Specifically, RTL < 0.6 could be used with age, sex, tumor size > 2cm and tumor invasion to predict the risk of PTC development and prognosis of the disease. This study will open new horizon in the use of molecular marker such as RTL for understanding its association with increased cancer risk in patients with different clinicopathological features.

A Machine Learning Classification Model for Gastrointestinal Health in Cancer Survivors: Roles of Telomere Length and Social Determinants of Health.

Gastrointestinal (GI) distress is prevalent and often persistent among cancer survivors, impacting their quality of life, nutrition, daily function, and mortality. GI health screening is crucial for preventing and managing this distress. However, accurate classification methods for GI health remain unexplored. We aimed to develop machine learning (ML) models to classify GI health status (better vs. worse) by incorporating biological aging and social determinants of health (SDOH) indicators in cancer survivors. We included 645 adult cancer survivors from the 1999-2002 NHANES survey. Using training and test datasets, we employed six ML models to classify GI health conditions (better vs. worse). These models incorporated leukocyte telomere length (TL), SDOH, and demographic/clinical data. Among the ML models, the random forest (RF) performed the best, achieving a high area under the curve (AUC = 0.98) in the training dataset. The gradient boosting machine (GBM) demonstrated excellent classification performance with a high AUC (0.80) in the test dataset. TL, several socio-economic factors, cancer risk behaviors (including lifestyle choices), and inflammatory markers were associated with GI health. The most significant input features for better GI health in our ML models were longer TL and an annual household income above the poverty level, followed by routine physical activity, low white blood cell counts, and food security. Our findings provide valuable insights into classifying and identifying risk factors related to GI health, including biological aging and SDOH indicators. To enhance model predictability, further longitudinal studies and external clinical validations are necessary.

Distinct microbiome dysbiosis and epigenetic anomaly in esophageal adenocarcinoma and its underlying Barrett’s esophagus

Interaction between host genotoxic changes and mucosa-associated microbiome (MAM) dysbiosis may have a role in various digestive cancers. We investigated MAM in Barrett’s esophagus (BE) and esophageal adenocarcinoma (EAC) progression sequence and its association with host genotoxic changes. 16S rRNA gene sequencing was performed in three different groups of biopsies from nonneoplastic BE from patients without cancer (N, normal group; n = 47) and with EAC (ADJ, adjacent group; n = 27). Endoscopic biopsies were also obtained from EAC tissues (T, tumor group; n = 22). Results were correlated with TP53 mutation, telomere length and DNA methylation of candidate genes (N33, DPYS, SLC16A12, miR124A3 and miR34bc). Genome-wide DNA methylation examined by reduced representation bisulfite sequencing (RRBS) was available for 32 samples (n = 12 for N, n = 12 for ADJ and n = 22 for T groups). Lower microbial alpha diversity measures were observed in ADJ/T groups relative to N group and associated with higher mean Z score DNA methylation of candidate genes. Specific genera (n = 16) with significant change between ADJ/T groups relative to N group occurred mostly in ADJ group (13/16) and half of them (8/16) were associated with DNA methylation status. Integrated MAM and genome-wide methylation analysis demonstrated that hyper-methylated sites, associated with lower alpha diversity measures dominantly occurred within near the transcription start site, codifying genes were involved in metabolic processes. Our result shows that microbial dysbiosis in EAC mostly occurs in adjacent BE and such dysbiosis was associated with DNA methylation status, offering support for a pathogenic role of interaction between host genotoxic changes and MAM in this tumor type.

Telomere length in relation to fecundability and use of assisted reproductive technologies: the Norwegian Mother, Father, and Child Cohort Study

BackgroundTelomere length (TL) has been reported to be associated with conditions such as endometriosis and polycystic ovary syndrome, with some studies finding associations with shorter TL and others with longer TL. In men, studies mostly report associations between shorter TL and sperm quality. To our knowledge, no studies have thus far investigated associations between TL and fecundability or the use of assisted reproductive technologies (ART).MethodsThis study is based on the Norwegian Mother, Father, and Child Cohort (MoBa) Study and uses data from the Medical Birth Registry of Norway (MBRN). We included women (24,645 with genotype data and 1054 with TL measurements) and men (18,339 with genotype data and 965 with TL measurements) participating between 1998 and 2008. We investigated associations between leukocyte TL (LTL) and fecundability (defined as the probability to conceive within a given menstrual cycle), infertility (defined has having spent 12 months or more trying to conceive without success), and ART use. We also repeated the analyses using instrumental variables for LTL consisting of genetic risk scores for LTL and genetically predicted LTL.ResultsApproximately 11% of couples had experienced infertility and 4% had used ART. LTL was not associated with fecundability in women (fecundability ratio [FR], 0.98; 95% confidence interval [CI], 0.92–1.04) or men (FR, 0.99; CI, 0.93–1.06), nor with infertility in women (odds ratio [OR], 1.03; CI, 0.85–1.24) or men (OR, 1.05; CI, 0.87–1.28). We observed an increased likelihood of using ART with increasing LTL in men (OR, 1.22; CI, 1.03–1.46), but not in women (OR, 1.10; CI, 0.92–1.31). No significant associations were observed using the instrumental variables for LTL.ConclusionsWe found no indication that LTL is a suitable biomarker for assessing fecundability, infertility, or ART use. Additional studies are required to replicate the association observed between LTL and ART use in men.

Telomere Dynamics in Zebrafish Aging and Disease.

Fish telomere lengths vary significantly across the numerous species, implicating diverse life strategies and environmental adaptations. Zebrafish have telomere dynamics that are comparable to humans and are emerging as a key model in which to unravel the systemic effects of telomere shortening on aging and interorgan communication. Here, we discuss zebrafish telomere biology, focusing on the organismal impact of telomere attrition beyond cellular senescence, with particular emphasis on how telomeric shortening in specific tissues can unleash widespread organ dysfunction and disease. This highlights a novel aspect of tissue communication, whereby telomere shortening in one organ can propagate through biological networks, influencing the aging process systemically. These discoveries position zebrafish as a valuable model for studying the complex interactions between telomeres, aging, and tissue cross talk, providing important insights with direct relevance to human health and longevity.

Evaluation of the effect of melatonin treatment on telomere length of the retinal pigment epithelium in streptozotocin-induced diabetic rat model

ObjectivesWe aimed to investigate the effect of diabetic retinopathy and melatonin treatment on the relative telomer lengths (RTL) in retinal pigment epithelium (RPE) cells in a streptozotocin-induced diabetic rat model.BackgroundTL can be used to evaluate diabetes mellitus, its complications, and the effectiveness of its treatment. However, TL assessment has not been performed in retinal cells in a diabetic retinopathy model until now.MethodsForty Sprague-Dawley male rats were randomly divided into four groups. The experimental groups were: Control Group (C): non- diabetic rats; Diabetes Mellitus Group (DM): rats induced to diabetes without treatment; Melatonin and Diabetes Mellitus Group (Mel + DM): rats induced to diabetes and after confirmation, treated with melatonin; Melatonin Group (Mel): rats were not induced to diabetes, treated with melatonin. Diabetes was induced by intraperitoneal administration of streptozotocin solution after 12 h food fasting. For eight weeks after the diabetes was induced, melatonin was administered via subcutaneous injection at a dose of 10 mg / kg. RTLs were measured by qPCR method with modifications. The comparison of averaged data among groups was performed using least significant difference (LSD) and Kruskal – Wallis Test and One way ANOVA test.ResultsRTL was significantly similar in control and melatonin group. RTL was thinnest in DM group, in addition melatonin treatment significantly prevented the RTL shortening in DM + Mel group (p = 0.031).ConclusionWe demonstrated that diabetic retinopathy led to the shortening of RTL in RPE cells in rats and melatonin treatment prevents this shortening.

Childhood Adversity and Telomere Length.

Purpose: Exposure to adversity during childhood and adolescence is associated with numerous health conditions in adulthood; telomere shortening may be a mechanism through which adversity contributes to poor outcomes. We studied three areas of adversity (parent relational instability, child household instability, and financial instability) occurring during three epochs across childhood and adolescence and their associations with telomere length during adolescence. Methods: Data were obtained from the first wave of a longitudinal cohort study of youth aged 11-17 and their primary caregiver. Caregivers completed demographic and adversity questionnaires; youth provided a saliva sample for DNA extraction for telomere analysis. Results: Of 879 youth, over half experienced some adversity. More than one third experienced parent relational instability in each age epoch, with nearly a quarter experiencing parent relational instability in all age epochs. Youth experienced a similar pattern of financial instability but lower rates of child household instability. Youth experiencing parent relational instability at two or three epochs had shorter telomeres compared to those without any parent relational instability (p < .004). Youth who experienced child household instability in two age epochs had shorter telomeres (p = .003) and youth who experienced financial instability across all three epochs had shorter telomeres (p = .013) compared to youth without these adversities. Conclusion: Continuing exposure to adversity in early childhood may be more likely to affect telomere length. Research is needed to further determine adversities exerting the most effect and to understand if early telomere shortening has long term health effects.

Day Late, Dollar Short: Runts of Asynchronously Hatched Songbird Broods Have Reduced Survival, Body Size, and Persistent Energy Deficits.

Many songbirds begin active incubation after laying their penultimate egg, resulting in synchronous hatching of the clutch except for a last-hatched individual ("runt") that hatches with a size deficit and competitive disadvantage to siblings when begging for food. However, climate change may elevate temperatures and cause environmental incubation as eggs are laid, resulting in asynchronous hatching and larger size hierarchies among siblings. Although previous work demonstrated that asynchronous hatching reduces nestling growth and survival relative to synchrony, the physiological mechanisms underlying these effects are unclear. To test the effects of asynchronous hatching on runt growth, survival, physiology, and compensatory growth-related tradeoffs, we manipulated incubation temperature in nest boxes of European starlings (Sturnus vulgaris) to increase asynchronous hatching and collected nestling morphological measurements and blood samples to assess physiology and development. Independent of heating treatment, runts from asynchronously hatched nests had lower survival than runts from more synchronous nests. Surviving runts from asynchronous nests were smaller and had reduced stress-induced corticosterone concentrations and reduced circulating glucose compared with runts from synchronous nests. Despite persistent size and energy deficits, runts from asynchronous nests did not have significant deficits in immunity or telomere length when compared with runts from synchronous nests, suggesting no trade-off between investment in immune development or telomere maintenance with growth. Overall, these results suggest that increased asynchrony due to climate change could reduce clutch survival for altricial songbirds, especially for the smallest chicks in a clutch, and that the negative effects of asynchrony may be driven by persistent energetic deficits.

Leucocyte telomere length and conduction system ageing

BackgroundDeterioration of the cardiac conduction system is an important manifestation of cardiac ageing. Cellular ageing is accompanied by telomere shortening and telomere length (TL) is often regarded as a marker...