Ageing before birth: pace and stability of prenatal growth affect telomere dynamics

Pre-natal effects on telomere length are increasingly recognized as a potential contributor to the developmental origin of health and adult diseases. While it is becoming clear that telomere length is strongly influenced by pre-natal conditions, the factors affecting telomere dynamics during embryogenesis remain poorly understood. We manipulated both the pace and stability of prenatal growth using incubation temperature in Japanese quail and investigated the impact on telomere dynamics from embryogenesis to adulthood, along with potential drivers of telomere shortening such as oxidative damage and prenatal glucocorticoid levels. Telomere length was not affected by these manipulations for the first 75% of prenatal development, but was reduced at hatching in response to both experimentally induced fast embryo growth and growth instability. These early-life effects on telomere length persisted until adulthood. The effect of developmental instability on telomere length at hatching was potentially mediated by an increased secretion of glucocorticoid hormones during development. Both the pace and the stability of prenatal growth appear as key factors determining telomere length and dynamics up to adulthood, with fast and unstable embryo growth leading to short telomeres with the potential for adverse associated outcomes in terms of reduced longevity and greater risk of disease.