The dynamics of gene expression during and post meiosis sets the sperm agenda

Meiosis is the defining event of spermatogenesis. Spermatocytes undergo meiosis to give rise to round spermatids, which in turn metamorphose to flagellated spermatozoa that mature in the epididymis. To characterize the dynamics of gene expression during these important stages of spermatogenesis, we undertook transcriptome analysis in >90% pure pachytene spermatocytes and round spermatids, and pure mature sperm of rat by massive parallel deep sequencing. The study has identified 10,719 total transcripts expressed in meiotic and postmeiotic cells, out of which 7,641 were present in all the three cell types. Most abundant transcripts were related to gametogenesis in spermatocytes and spermatids, and mitochondrial energy metabolism in sperm. Importantly, 108 transcripts were specific to spermatocytes, including Cpeb2, Dpf3, H2afy, Haus7, Plcb1, Taf9, and Tdrd7 strongly linked with meiosis. Similarly, 323 transcripts unique to round spermatids included Arpc5, Apoa1, Cntrob, Dcaf17, Ift88, and Ly6k that play essential roles in spermiogenesis. Likewise, 178 transcripts unique to sperm included Camta1, Hoxb1, and Prdx6 having assigned roles in fertility and/or embryonic development. Levels of ~16% transcripts declined from spermatocytes to sperm while two (Cd300e and Ddx17) increased. New candidate genes with possible roles in meiosis (91), spermiogenesis (298), and sperm function (171), have been identified. This study has provided new potential targets for contraception and/or treatment of male infertility. (CDRI communication number 9889).