MINIBRAIN - A NEW-PROTEIN KINASE FAMILY INVOLVED IN POSTEMBRYONIC NEUROGENESIS IN DROSOPHILA

The development of the adult central nervous system of Drosophila requ ires a precise and reproducible pattern of neuroblast proliferation du ring postembryonic neurogenesis. We show here that mutations in the mi nibrain (mnb) gene cause an abnormal spacing of neuroblasts in the out er proliferation center (ope) of larval brain, with the implication th at mnb ope neuroblasts produce less neuronal progeny than do wild type . As a consequence, the adult mnb brain exhibits a specific and marked size reduction of the optic lobes and central brain hemispheres. The insufficient number of distinct neurons in mnb brains is correlated wi th specific abnormalities in visual and olfactory behavior. The mnb ge ne encodes a novel, cell type-specific serine-threonine protein kinase family that is expressed and required in distinct neuroblast prolifer ation centers during postembryonic neurogenesis. The mnb kinases share extensive sequence similarities with kinases involved in the regulati on of cell division.