Anatomy of mouse recombination hot spots

Genome-wide analyses have suggested thousands of meiotic recombination hot spots across mammalian genomes. However, very few hot spots have been directly analyzed at a sub-kb scale for crossover (CO) activity. Using recombinant inbred strains as a CO library, here we report the identification and detailed characterization of seven new meiotic hot spots on mouse chromosome 19, more than doubling the number of currently available mouse hot spots. Although a shared feature is the narrow 1.5–2.5-kb width of these recombinogenic sites, these analyses revealed that hot spots have diverse sequence attributes and distinct symmetric and asymmetric CO profiles. Interestingly, CO molecules with discontinuous conversion tracts are commonly observed, contrasting with those found in human. Furthermore, unlike human hot spots, those present in the mouse do not necessarily have a quasi-normal CO distribution but harbor CO repulsion zones within recombinogenic cores. We propose a model where local chromatin landscape directs these repulsion zones

A Global Expression Switch Marks Pachytene Initiation during Mouse Male Meiosis

Male spermatogenesis is an essential and complex process necessary to gain totipotency and allow a whole new organism to develop upon fertilization. While single-gene based studies have provided insights into the mechanisms underlying spermatogenesis, detailed global profiling of all the key meiotic stages is required to fully define these processes. Here, by isolating highly enriched mouse meiotic cell populations, we have generated a comprehensive gene expression atlas of mammalian meiosis. Our data define unique signatures for the specific stages of meiosis, including global chromosome X inactivation and reactivation. The data also reveal profound switches in global gene expression at the initiation of pachynema that are reminiscent of the commitment to meiosis observed in budding yeast. Overall, this meiotic atlas provides an exhaustive blueprint and resource for mammalian gametogenesis and meiosis

A Global Expression Switch Marks Pachytene Initiation during Mouse Male Meiosis

Male spermatogenesis is an essential and complex process necessary to gain totipotency and allow a whole new organism to develop upon fertilization. While single-gene based studies have provided insights into the mechanisms underlying spermatogenesis, detailed global profiling of all the key meiotic stages is required to fully define these processes. Here, by isolating highly enriched mouse meiotic cell populations, we have generated a comprehensive gene expression atlas of mammalian meiosis. Our data define unique signatures for the specific stages of meiosis, including global chromosome X inactivation and reactivation. The data also reveal profound switches in global gene expression at the initiation of pachynema that are reminiscent of the commitment to meiosis observed in budding yeast. Overall, this meiotic atlas provides an exhaustive blueprint and resource for mammalian gametogenesis and meiosis