The centrosome in Drosophila oocyte development

摘要: The Drosophila oocyte is a highly specialized cell type whose development utilizes MTOCs in various contexts. Figure 4 (see color insert) summarizes the characteristics of at different stages oogenesis. Polarized mitoses are required to achieve determination. In asymmetric germ-cell divisions that culminate egg chamber, mitotic centrosomes anchored spectrosome or fusome order produce regular branching pattern cyst cells. It appears primary role orchestrate polarity and synchrony oogenic mitoses. absence fusomes spindles, interconnected network lost does not differentiate. known if spindle itself asymmetric, whether either centrosome has equal potential interact with fusome. Several models can explain need for polarized differentiation. one, an unequal distribution unknown differentiation factors occurs from as early first cystoblast division. Here, may be factors. another model, there mechanism measures number ring canals cell, limiting choice two pro-oocytes. this polarized, synchronous must occur only cells highest canals. both these plays indirect role. A critical event determination formation MTOC. MTOC forms shortly after completion germ establishes microtubule array along which transported. unclear how single 16-cell cyst, become inactivated adjoining 15 nurse cells, why centrioles transported into oocyte. No molecular components except centrosomin, accumulates relatively late, approximately stage 5 6 central establishing oocyte's polar coordinates. localization axis-determining At midoogenesis mediate reversal migration nucleus posterior follicle signal receiving gurken signal. What changes trigger cytoskeletal rearrangement? better understanding MTOC's necessary before we begin unravel mechanisms underlying events. morphology it shifts anterior. Staining anti-centrosomin antibodies shows discrete nucleus-associated bodies broad structure associated anterior cortex. structural rearrangement presently unknown. Meiosis I centrosomes, but meiosis II spindles linked by shared, acentriolar, astral organization poles requires NCD motor protein; however, acentriolar contain no centrosomal core proteins. pole unique ring-shaped contains proteins, such gamma-tubulin. Strong mutations maternal gamma Tub37C gene do block I, prevent progression II.