Persistence of parental age effect on somatic mutation rates across generations in Arabidopsis.

In the model plant Arabidopsis thaliana, parental age is known to affect somatic mutation rates in their immediate progeny but it is not clear if this age-associated effect on mutation rates persist across successive generations. Using a set of detector lines carrying the mutated uidA gene, we examined if a particular parental age maintained across five consecutive generations affected the rates of base substitution (BSR), intrachromosomal recombination (ICR), frameshift mutation (FS), and transposition. The frequency of functional GUS (blue colored spots) reversions were examined in seedlings as a function of identical/different parental ages across generations. When parental age remained constant, no change was observed in BSR/ICR rates in the first three generations, following which it drops significantly in the 4th and in most instances, is elevated in the 5th generation. On the other hand, with advancing parental age, BSR/ICR rates respectively remained high in the first two/three generations with a striking resemblance in the pattern of mutation rates. We followed a novel approach of identifying and tagging flowers pollinated on a particular day, thereby avoiding possible emasculation induced stress responses, as it may influence mutation rates. By and large there is no correlation in the expression of candidate genes involved in DNA repair to the pattern of reversion events and possibly, the expression patterns may correspond to the genomewide somatic mutations rates. Our results suggest a time component in counting the number of generations a plant has passed through self-fertilization at a particular age in determining the somatic mutation rates.

Maternal and paternal age effects on male antler flies: a field experiment

In many species, parental age at reproduction can influence offspring performance and lifespan, but the direction of these effects and the traits affected vary among studies. Data on parental age effects are still scarce in non-captive populations, especially insects, despite species such as fruit flies being models in laboratory-based aging research. We performed a biologically relevant experimental manipulation of maternal and paternal age at reproduction of antler flies (Protopiophila litigata) in the laboratory and tracked the adult lifespan and reproductive success of their male offspring released in the wild. Increased paternal, but not maternal, age somewhat increased sons’ adult lifespan, while parental ages did not influence sons’ mating rate or reproductive senescence. Our results indicate that while parental age effects do exist in an insect in the field, they may be beneficial in such a short-lived animal, in contrast to results from most wild vertebrates and laboratory invertebrates.

Delayed parenthood and its influence on offspring health: What have we learned from the mouse model

Delayed parenthood is constantly increasing worldwide due to various socio-economic factors. In the last decade, a growing number of epidemiological studies have suggested a link between advanced parental age and an increased risk of diseases in the offspring. Also, poor reproductive outcome has been described in pregnancies conceived by aged parents. Similarly, animal studies showed that aging negatively affects gametes, early embryonic development, pregnancy progression and the postnatal phenotype of resulting offspring. However, how and to what extent parental age is a risk factor for the health of future generations is still subject to debate. Notwithstanding the limitation of an animal model, the mouse model represents a useful tool to understand not only the influence of parental age on offspring phenotype but also the biological mechanisms underlying the poor reproductive outcome and the occurrence of diseases in the descendants. The present review aims at i) providing an overview of the current knowledge from mouse model about the risks associated with conception at advanced age (e.g. neurodevelopmental and metabolic disorders), ii) highlighting the candidate biological mechanisms underlying this phenomenon, and iii) discussing on how murine-derived data can be relevant to humans.

Genetic Investigation of 261 Cases of Turner Syndrome Patients Referred to the Genetic Clinic

Background: Turner syndrome (TS), also known as 45,X, is a genetic disorder caused by the partial or complete lack of an X chromosome. TS can cause a variety of medical and developmental conditions. We aimed to investigate TS mosaicism and variants pattern and research the presence of a correlation between the different variant’s factors and TS occurrence. Methods: From 1984-2018, 100,234 patients referred to the Farhud Genetic Clinic, Tehran, Iran, for karyotyping were studied. TS was determined by the chromosomal assay, and the patients’ karyotype was obtained from amniotic fluid and blood samples. Different variants of the TS diagnosed patients were investigated, including maternal and paternal age at pregnancy, parental consanguinity, and the presence/absence of a family history of the disease. Results: Overall, 261/100,234 (0.26%) were diagnosed with TS. These, 150 cases were identified to have the classical 45,X karyotype and 111 cases were identified to have either TS mosaicism or other less common variations of TS karyotyping. Higher parental age at pregnancy and TS data suggested that the occurrence of TS is significantly higher. Conclusion: Data suggest parental age at pregnancy is an important factor for TS occurrence. Hence, prenatal screening in these groups of parents recommended. This study also implicates early medical diagnostic testing before the onset of puberty or as soon as symptoms arise is essential for early treatment.

Beneficial cumulative effects of old parental age on offspring fitness

Old parental age is commonly associated with negative effects on offspring life-history traits. Such parental senescence effects are predicted to have a cumulative detrimental effect over successive generations. However, old parents may benefit from producing higher quality offspring when these compete for seasonal resources. Thus, old parents may choose to increase investment in their offspring, thereby producing fewer but larger and more competitive progeny. We show that Caenorhabditis elegans hermaphrodites increase parental investment with advancing age, resulting in fitter offspring who reach their reproductive peak earlier. Remarkably, these effects increased over six successive generations of breeding from old parents and were subsequently reversed following a single generation of breeding from a young parent. Our findings support the hypothesis that offspring of old parents receive more resources and convert them into increasingly faster life histories. These results contradict the theory that old parents transfer a cumulative detrimental ‘ageing factor’ to their offspring.