Ocnus is essential for male germ cell development in Drosophila melanogaster

The ocnus (ocn) gene encodes a protein abundant in the testes, implying its role in testis development. When Drosophila melanogaster is infected with the endosymbiont wMel Wolbachia, which affects the spermatogenesis of its hosts, ocn is downregulated in the third‐instar larval testes, suggesting a role of ocn in spermatogenesis. In this study, we knocked down ocn in the testes and found that the hatch rates of embryos derived from ocn‐knockdown males were significantly decreased, and 84.38% of the testes were much smaller in comparison to controls. Analysis of the smaller testes showed no germ cells but they had an extended hub. Using RNA‐sequencing (RNA‐Seq), we identified 69 genes with at least a twofold change (q‐value