RNA LOCALIZATION ALONE THE ANTEROPOSTERIOR AXIS OF THE DROSOPHILA OOCYTE REQUIRES PKA-MEDIATED SIGNAL-TRANSDUCTION TO DIRECT NORMAL MICROTUBULE ORGANIZATION

Microtubule polarity has been implicated as the basis for polarized lo calization of morphogenetic determinants that specify the anteroposter ior axis in Drosophila oocytes. We describe mutations affecting Protei n Kinase A (PKA) that act in the germ line to disrupt both microtubule distribution and RNA localization along this axis. In normal oocytes, the site of microtubule nucleation shifts from posterior to anterior immediately prior to polarized localization of bicoid and oskar RNAs. In PKA-deficient oocytes, posterior microtubules are present during th is transition, oskar RNA fails to accumulate at the posterior, and bic oid RNA accumulates at both ends of the oocyte. Similar RNA mislocaliz ation patterns previously reported for Notch and Delta mutants suggest that PKA transduces a signal for microtubule reorganization that is s ent by posteriorly located follicle cells.