Impaired chromosome segregation results in sperms with excess centrosomes in emb-27APC6 mutant C. elegans

Abstract

The anaphase-promoting complex (APC) is a major regulator of chromosome segregation and is implicated in centriole engagement, whose de-regulation causes abnormal number of centrosomes. The emb-27 gene in C. elegans encodes a subunit of APC. The paternal emb-27 mutant was reported to show cell division with multiple furrows, suggesting the presence of excess centrosomes. In this study, we examined the number of centrosomes and the mechanism underlying de-regulation of centrosome number in emb-27 mutants. Our observations indicated excess centrosomes in emb-27 sperms, which resulted in zygotes with excess centrosomes. Further, the secondary spermatocyte of emb-27 produced reduced number of spermatids, which is likely the direct cause of the excess number of centrosomes per sperm. We propose that a chromosome segregation defect in emb-27 induced centrosome separation defect, resulting in reduced number of buds. Additionally, treatment with cytoskeletal inhibiting drugs indicated presence of three kinds of forces working in combination to move the centrosomes into the spermatids. The present study suggested a novel role of microtubule in the budding cytokinesis of spermatocytes.