The major objective of this research project is to determine how cell lineage, developmental hormones, cell interactions and developmental genes influence the fate of neurons within the developing nervous system of an insect. Within the nervous system of the moth, Manduca sexta , adult specific neurons are generated during the larval stage by arrays of neuroblasts. Each neuroblast generates a nest of developmentally arrested progeny. With the onset of metamorphosis the development of the adult specific neurons resumes. Electrophysiological techniques will be employed to determine both the physiological and morphological properties of the arrested cells during the larval stage and as they develop into mature neurons. The influence of the developmental hormones on the fate of the new neurons will be examined. Using surgical manipulations, Dr. Booker will also determine if the size of the periphery influences the fate of the adult specific neurons. The role of segmental determination in the development of the insect nervous system will be examined using two approaches. First, a screen for new homeotic mutations in the moth will be conducted. The new mutants will be analyzed to determine if they influence the fate of identifiable pattern elements within the segmental ganglia. Second, DNA in Manduca which shares homology with the homeobox genes of Drosophila melanogaster will be cloned. The cloned moth genes will be characterized as to the temporal and spatial pattern of their expression within the segmented ganglia of both wild.type and mutant animals. These complimentary approaches will further the understanding of the role of the developmental genes in segmental and neuronal determination.
