Cell polarity or asymmetry is a universal feature of animal cells that is fundamental to the development and morphogenesis of all organisms. For developmental biologists the recognition that determinants prelocalized within the oocyte act to control axial polarities and cell fates within the embryo has focused great interest on the identity of those determinants and the mechanism of their localization. The unidirectional movements of the microtubule-associated motors, dyneins, and kinesins, provide an important mechanism for the positioning of cellular organelles and molecules. This mechanism may underlie the polarized transport and targeting of morphogenetic determinants within oocytes and embryos. The proposed research will test this hypothesis. Our previous analysis of recessive lethal dynein mutations has indicated that dynein function is required during oogenesis. Moreover, an aymmetric accumulation of the dynein motor to, and within, the oocyte is disrupted by mutations in genes that are required for oocyte specification and differentiation. Our planned experiments will (1) characterize the cytological and molecular phenotypes of oocytes that are mutant for dynein function, (2) test the hypothesis that cytoskeletal polarity is an underlying component of oocyte asymmetry which accounts for dynein accumulation and localization within the oocyte, and (3) to extend our genetic and molecular analyses of the pathways for cytoskeletal transport in oogenesis. Overall, these studies are designed to enhance understanding of the roles of motor proteins in the specification of embryonic axes in the fly egg chamber in articular and the generation of cell olarity in general.
