Retention of paternal epigenetic memory in the developing teleost germline [RNA-Seq]

Two waves of DNA methylation reprogramming occur during mammalian embryogenesis; during preimplantation development and during primordial germ cell (PGC) formation. However, it is currently unclear how evolutionarily conserved these processes are. Here we characterize the DNA methylomes of zebrafish PGCs at four developmental stages and unravel retention of paternal epigenetic memory, in stark contrast with the findings in mammals. Gene expression profiling of zebrafish PGCs at same developmental stages revealed that the embryonic germline is defined by a small number of markers that display strong developmental stage-specificity and that are uncoupled from DNA methylation-mediated regulation. Using low-input RNA-seq we have profiled transcriptomes of zebrafish primordial germ cells (PGCs) and age-matched somatic cells at 4 (blastula), 7 (gastrula), 24 (pharyngula prim-5) and 36 (pharyngula prim-25) hours post-fertilization