The Drosophila centriole - conversion of doublets into triplets within the stem cell niche

We report, here, that two distinct centriole lineages exist in Drosophila: somatic centrioles usually composed by microtubule doublets and germ line centrioles characterized by triplets. Remarkably, the transition from doublets to triplets in the testis occurs within the stem cell niche with the formation of the C-tubule. We demonstrated that the old mother centriole, which stays in the apical cytoplasm of the male germline stem cells (GSCs), is invariably composed of triplets, whereas its daughter is always built of mixed doublets and triplets. This difference represents the first documentation of a structural asymmetry between mother and daughter centrioles in Drosophila GSCs and might reflect a correlation between the architecture of parent centrioles and their ability to recruit centrosomal proteins. We also found that the old mother centriole is linked to the cell membrane by distinct projections that might play an important role in keeping its apical position during centrosome separation.