ASYMMETRY AND CELL FATE IN THE DROSOPHILA EMBRYONIC CNS

Drosophila CNS precursors, neuroblasts, repeatedly divide to produce a large neuroblast and a smaller GMC. This division is asymmetric with regard to sibling cell size, mitotic potential and gene expression. Re cent work has identified a number of molecules that show a polarized d istribution during neuroblast mitosis: prospero RNA and Inscuteable, M iranda, Prospero, Staufen, and Numb proteins. The process of asymmetri c localization of proteins and RNAs is cell cycle dependent, microfila ment dependent and coordinated with the positioning of the mitotic spi ndle, which results in the unequal distribution of cell fate determina nts to a specific daughter cell at cytokinesis.