Sex allocation theory predicts that facultative maternal investment in the rare sex should be favoured by natural selection when breeders experience predictable variation in adult sex ratios (ASRs). We found significant spatial and predictable interannual changes in local ASRs within a natural population of the common lizard where the mean ASR is female-biased, thus validating the key assumptio...

Animal personalities are common across taxa and have important evolutionary and ecological implications. Such consistent individual differences correlate with important life-history traits such as dispersal. Indeed, some environmental conditions are supposed to determine dispersers with a specific personality. For example, an increased density should promote the departure of individuals with le...

The occurrence of DNA fragmentation in mammalian spermatozoa was identified in 1993. In human, sperm DNA fragmentation is particularly relevant in subfertile patients (i.e, those subjects more likely to be treated by assisted reproductive techniques). Thus, concerns have been raised about the possibility that sperm with DNA fragmentation may be involved in the process of fertilization, in parti...

Nucleoplasmin, an acidic thermostable protein abundant in the nucleus of Xenopus laevis oocytes, has been found to dissociate complexes of pUC19 DNA and protein phi 1, an intermediate protamine present in ripe sperm from the mollusc Mytilus edulis. Cruder preparations of nucleoplasmin, such as the amphibian oocyte S150 extract and its thermostable fraction, also dissociate the heterologous DNA-...

Human embryonic stem cells (hESCs) and induced pluripotent stem cells (hiPSCs) have been shown to differentiate into primordial germ cells (PGCs) but not into spermatogonia, haploid spermatocytes, or spermatids. Here, we show that hESCs and hiPSCs differentiate directly into advanced male germ cell lineages, including postmeiotic, spermatid-like cells, in vitro without genetic manipulation. Fur...

The presence of specific messenger RNAs in the nuclei of mature mammalian spermatozoa has been demonstrated by several independent laboratories. Others have suggested that various polymerases may also be active in mature spermatozoa. This has led to the notion that the 'sleeping' genome may not be so quiescent after all. The alternate use of somatic-like nucleosomal and haploid protamine packag...

We investigated the respiratory metabolism of the overwintering lizard Lacerta vivipara while in either supercooled or frozen states. With a variable pressure and volume microrespirometer and a chromatograph, we show that the oxygen consumption of the supercooled animals showed a nonlinear relationship with temperature and an aerobic metabolism demand between 0.5 and -1.5 degrees C. A significa...

Although multiple condition dependence in dispersal is common, the proximate mechanisms that integrate information from multiple sources remain largely unknown. In the common lizard (Lacerta vivipara), earlier studies have shown that maternal plasma corticosterone level interacts with maternal phenotype to affect offspring phenotype and dispersal strategy, and may reflect the mother's external ...