DNA methylatio of retrotransposon of male germ cells

DNA methylation is one of critical epigenetic marks for male germ cell development. This DNA methylation is dynamically regulated during embryonic male germ cell development. DNA methylation is largely erased around embryonic day 13 to 15. Then, DNA methylation is re-established around embryonic day 16 to 18, called de novo DNA methylation. Small non-coding RNA, piRNA (PIWI-interacting RNA) was reported to essential for de novo DNA methylation of a specific retrotransposon, however, the whole pictures are still largely unknown. Here, we performed whole genome bisulfite sequence of Mili- and Miwi2-null germ cells by novel method, named PBAT (Post-bisulfite adaptor tagging) . Mili-null germ cells showed severely impaired piRNA production, namely piRNA deficient mutant. MIWI2 protein is believed as an essential protein for secondary processing of piRNA and nuclear effector with piRNA. Comparing the impaired DNA methylation of the mutant male germ cells, gives more information.