The CNS midline cells and spitz class genes are required for proper patterning of Drosophila ventral neuroectoderm

The Drosophila embryonic central nervous system (CNS) develops from sets of neuroblasts (NBs) which segregate from the ventral neuroectoderm during ea rly embryogenesis. It is not well established how each individual NE in the neuroectoderm acquires its characteristic identity along the dorsal-ventra l axis. Since it is known that CNS midline cells and spitzclass genes (poin ted, rhomboid, single-minded, spitz and Star) are required for the proper p atterning of ventral CNS and epidermis originated from the ventral neuroect oderm, this study was carried out to determine the functional roles of the CNS midline cells and spitz class genes in the fate determination of ventra l NBs and formation of mature neurons and their axon pathways. Several mole cular markers for the identified NBs, neurons, and axon pathways were emplo yed to examine marker gene expression profile, cell lineage and axon pathwa y formation in the spitz class mutants. This analysis showed that the CNS m idline cells specified by single-minded gene as well as spitz class genes a re required for identity determination of a subset of ventral NBs and for f ormation of mature neurons and their axon pathways. This study suggests tha t the CNS midline cells and spitzclass genes are necessary far proper patte rning of the ventral neuroectoderm along the dorsal-ventral axis.