Kinetics of histone and protamine synthesis during meiosis and spermiogenesis in the mouse

The separation of mouse spermatogenic cell nuclei by sedimentation velocity at unit gravity has been used to determine the timing of histone and "mouse protamine" synthesis, and the turnover of basic nuclear proteins throughout spermatogenesis. Animals were injected with 3H-arginine or 3H-lysine and at various time intervals (2 hours post-label or from 1 to 30 days post-label) germinal cell nuclei preparations were separated on the staput. Labelled histones and mouse protamine were extracted from staput separated nuclei with hydrocholoric acid and fractionated by polyacrylamide gel electrophoresis. Results indicate that histones are synthesized in association with DNA replication in spermatogonia and preleptotene spermatocytes, in pachytene primary spermatocytes and in spermatids stages 11-16, simultaneously with "mouse protamine". Experiments are reported showing that histones synthesized in pachytene primary spermatocytes and in spermatids stages 11-16 are retained in epididymal spermatozoa, while histones synthesized before meiosis are no longer detectable onto chromatin after meiosis.