PROFILIN IS REQUIRED FOR POSTERIOR PATTERNING OF THE DROSOPHILA OOCYTE

We have investigated the role of the actin cytoskeleton during mid-oog enesis and have found that disrupting the actin cytoskeleton with cyto chalasin D induces microtubule bundling and microtubule-based cytoplas mic streaming within the oocyte, similar to that which occurs prematur ely in cappuccino and spire mutant oocytes. After examining a number o f mutants that affect the actin cytoskeleton, we have found that chick adee, which encodes the actin-binding protein, profilin, shares this p henotype. In addition to the microtubule misregulation, mutants in chi ckadee resemble cappuccino in that they fail to localize STAUFEN and o skar mRNA to the posterior pole of the developing oocyte. Also, a stro ng allele of cappucccino has multinucleate nurse cells, similar to tho se previously described in chickadee. In an independent line of experi ments, we have identified profilin as a CAPPUCCINO interactor in a two -hybrid screen for proteins that bind to CAPPUCCINO. This, together wi th the similarity of mutant phenotypes, suggests that profilin and CAP PUCCINO may interact during development.