We utilized the powerful molecular and genetic tools available for the analysis of neural development in Drosophila to characterize a mutation for its effects on imaginal sensory axons. Previous analysis demonstrated that loss of function alleles caused defects in axon anatomy. Molecular analysis revealed that these axon defects were due to a disruption in the 10.4 kDa cytoplasmic dynein light chain gene (Cdlc1). This molecular analysis involved the recovery of both genomic and cDNA clones, characterization of the transcription unit in both wild type and mutants, and sequence analysis. As verification that mutations in the cytoplasmic dynein light chain gene caused the axon defects, we generated transgenic flies in which expression of the gene was targeted to specific sensory neurons. When this targeting system was introduced into a Cdlc1$\rm\sp{null}$ genetic background the axon phenotype of the targeted neurons was rescued. Further, the rescuing effects of the targeted expression was restricted to the Cdlc1-positive neurons. Other sensory neurons that were not expressing the transgene in this system retained mutant axon phenotypes. The specificity of the rescue demonstrated that Cdlc1 function is cell autonomous, and that sensory neurons require Cdlc1 function for proper development of their axon projections. The dynein light chain has been shown to associate with the cytoplasmic dynein complex, myosin V and nitric oxide synthase. All of these molecules have neural function so it is important to determine whether any of these partners were involved in producing the axon defects we observed in Cdlc1 mutants. In Drosophila, mutant alleles are only available for genes encoding components of the cytoplasmic dynein complex. We used these alleles in a double mutant analysis to determine whether the axon phenotype was influenced by genetic interactions between mutations affecting the light chain and the dynein heavy chain and p150$\rm\sp{Glued}.$ Our data showed that loss of function mutations in the heavy chain gene acted as dominant suppressors of the Cdlc1 axon phenotype, while loss of function mutations in Glued acted as dominant enhancers of the phenotype. These results support a model in which the light chain functions with the cytoplasmic dynein complex during axon development.
| Identifer | oai:union.ndltd.org:UMASS/oai:scholarworks.umass.edu:dissertations-3013 |
| Date | 01 January 1998 |
| Creators | Statton, Debbie Marie |
| Publisher | ScholarWorks@UMass Amherst |
| Source Sets | University of Massachusetts, Amherst |
| Language | English |
| Detected Language | English |
| Type | text |
| Source | Doctoral Dissertations Available from Proquest |
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