gamma-Tubulin function during female germ-cell development and oogenesis in Drosophila.

A series of unconventional microtubule organizing centers play a fundamental role during egg chamber development in Drosophila. To gain a better understanding of their molecular nature, we have studied the centrosomal component gamma-tubulin during Drosophila oogenesis. We find that although single mutations in either of the two gamma-tubulin genes identified in Drosophila do not affect oogenesis progression the simultaneous depletion of both protein products has severe consequences. The combination of loss-of-function mutant alleles for the two gamma-tubulin genes leads to mitotic defects in female germ cells, resulting in agametic ovaries. A combination of weaker mutant alleles instead allows female germ-cell development to proceed, although the resulting egg chambers display pleiotropic abnormalities, most frequently affecting the number of nurse cells and oocytes per egg chamber. Thus, gamma-tubulin is required for several processes at different stages of germ-cell development and oogenesis, including oocyte determination and differentiation. Our data provide a functional link between a component of the peri-centriolar material, such as gamma-tubulin, and microtubule organization during Drosophila oogenesis. In addition, our results show that gamma-tubulin is required for female germ-cell proliferation and that the two gamma-tubulins present in Drosophila are functionally equivalent during female germ-cell development and oogenesis.