Chinese scientists have revealed that the DNA methylome of sperm, not oocytes, is inherited by offspring. This was discovered by a team led by Professor Liu Jiang from Beijing Institute of Genomics, Chinese Academy of Sciences. Their findings were published in leading international academic journal Cell as a cover story on May 9th.

All the cells in one animal have the same DNA set, but there are more than 200 different cells with different phenotype and functions. Recent studies show the epigenetic information can regulate the cell differentiation. But whether the epigenetic information can be inherited is limited known.

DNA methylation is one major type of epigenetic information. The research team used zebrafish as the model organism to study the inheritance of sperm methylome, as zebrafish is a good vertebrate model whose genome has 85 percent genetic similarity to human beings. They found that paternal methylome pattern is stably maintained in the offspring’s embryos, while maternal methylome is discarded and reprogrammed progressively to become sperm methylome. Therefore, their study illustrates that sperm, but not oocyte, methylome is inherited by zebrafish early embryos.

Their study subverted the commonly accepted notion that early embryo development is only defined by oocyte, while sperm plays almost no roles during embryo development. Compared to oocyte, sperm has quite smaller cellular volume with limited RNAs and proteins. Therefore, it’s commonly believed that the majority information for the embryogenesis of offspring is carried by egg, and sperm just carries one set DNA. Their study shows that besides DNA can be inherited, sperm DNA methylome can also be inherited in zebrafish. And the inheriting sperm methylome can facilitate the embryogenesis.

This research will facilitate the development of regeneration medicine, cloning and even some diseases treatment.