RpS24 Is Required for Meiotic Divisions and Spermatid Differentiation During <i>Drosophila</i> Spermatogenesis

In Drosophila, testes contain highly heterogeneous ribosome populations. Several ribosomal proteins (RPs) have been shown to play specific and distinct roles during different stages of spermatogenesis. However, the detailed functions and mechanisms of RPs in spermatogenesis remain unclear. Here, we analyzed the function of RpS24 during Drosophila spermatogenesis. RpS24 is required for sperm production and male fertility of adult flies. Loss of RpS24 causes defects in meiotic chromosome segregation and cytokinesis, failures of spermatid elongation with incomplete axoneme assembly, and twisted mitochondrial derivatives. To trace back the cause of these defects, we found that RpS24 inhibition resulted in the abnormal number and localization of centrosomes in spermatocytes that led to the formation of irregular spindles. During the subsequent elongation process, the centrosome-derived basal body was unable to couple with the nucleus and underwent degradation that impaired microtubule elongation in the RpS24-knockdown spermatid. Our findings indicated that RpS24 may play a necessary role in maintaining the structural stability of centrosomes, therefore affecting spindle assembly in spermatocytes and the subsequent basal body formation and function in spermatids, which are essential for meiotic chromosome segregation, cytokinesis, and flagellum elongation in Drosophila testes.