Cell-type-specific genomics reveals histone modification dynamics in mammalian meiosis

Meiosis is the specialized cell division during which parental genomes recombine to create genotypically unique gametes. Despite its importance, mammalian meiosis cannot be studied in vitro, greatly limiting mechanistic studies. In vivo, meiocytes progress asynchronously through meiosis and therefore the study of specific stages of meiosis is a challenge. Here, we describe a simple method for isolating pure sub-populations of meiocytes that allows for detailed study of meiotic sub-stages. Interrogating the H3K4me3 landscape revealed dynamic chromatin transitions between sub-stages of meiotic prophase I, both at sites of genetic recombination and at gene promoters. We also leveraged this method to perform the first comprehensive, genome-wide survey of histone marks in meiotic prophase, revealing a heretofore unappreciated complexity of the epigenetic landscape at meiotic recombination hotspots. Ultimately, this study presents a simple, scalable framework for interrogating the complexities of mammalian meiosis. We devised a method to isolate specific populations of meiotic nuclei from whole testis of mice. We subsequently interrogated the dynamic histone modification landscape using ChIP-Seq.