Post-meiotic transcription in Drosophila testes.

Post-meiotic transcription was accepted to be essentially absent from Drosophila spermatogenesis. We identify 24 Drosophila genes whose mRNAs are most abundant in elongating spermatids. By single-cyst quantitative RT-PCR, we demonstrate post-meiotic transcription of these genes. We conclude that transcription stops in Drosophila late primary spermatocytes, then is reactivated by two pathways for a few loci just before histone-to-transition protein-to-protamine chromatin remodelling in spermiogenesis. These mRNAs localise to a small region at the distal elongating end of the spermatid bundles, thus they represent a new class of sub-cellularly localised mRNAs. Mutants for a post-meiotically transcribed gene (scotti), are male sterile, and show spermatid individualisation defects, indicating a function in late spermiogenesis.