Fish exhibit an extraordinary phenotypic plasticity facing environmental variations. In addition, they are able to transmit information on their life history to their offspring, susceptible to compromise their performances or, in contrary, allow a better acclimation to changing environments. This non-genetic information is transmitted via gametes and DNA methylation is an excellent candidate for being a molecular vector of inter- and even transgenerational inheritance. It is indeed sensitive to the environment and in male fish gamete, it plays a demonstrated role in the kinetics of zygotic genes activation (studies performed in zebrafish). However, the question of methylome alterations induced by the environment and transmitted throughout generations via the gametes remains to be addressed. We have demonstrated in a previous work that sperm DNA methylome is altered upon a 4°C increase in temperature during spermatogenesis in rainbow trout. We now seek to test, in an appropriate fish model exhibiting a short generation time, the inter- and transgenerational transmission of this temperature-induced effect. We therefore propose to perform, using medaka fish, an exhaustive phenotyping of spermatozoa from males exposed to an increased rearing temperature during spermatogenesis at the cellular (functionality) and molecular (transcriptomics) levels and study the effect of temperature on the sperm methylome at whole genome scale and CpG resolution level. Inter- and transgenerational transmission of phenotypic and/or epigenetic alterations will then be tested, as well as the capacity of males to acclimate to the similar thermal treatment from generation to generation.

Partners : Antoine Rolland Université de Rennes - Irset with Frédéric Chalmel and Bertrand Evrard.