LOCALIZED RNAS ARE ENRICHED IN CYTOSKELETAL EXTRACTS OF DROSOPHILA OOCYTES

Maternal mRNAs localized within the Drosophila oocyte encode positiona l information which specifies the pattern of the early embryo. With th e goal of identifying molecules involved in RNA localization, we have developed a subcellular fractionation procedure which enriches for loc alized RNAs. Most RNAs and cellular proteins are solubilized by this m ethod and are recovered in the supernatant fraction. However, five loc alized RNAs we examined are recovered in the detergent-insoluble pelle t, despite temporal and spatial differences in their patterns of expre ssion. These RNAs appear to be associated with a large, detergent-inso luble component of the oocyte. This association is specific for the oo cyte proper, as localized RNAs in nurse cells and early embryos do not show this behavior. The fractionation behavior of these RNAs appears directly related to their localization in the oocyte, since fractionat ion and localization exhibit the same cytoskeletal and genetic require ments. The cortical cytoskeleton of the oocyte is a likely candidate f or the localization substratum. (C) 1994 Academic Press, Inc.