Morphogenesis of the nervous system using the neurological mutants of the nematode based on molecular genetics

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Microtubules are cylindrical structures, composed mainly of alpha and beta tubulin and several associated proteins. In higher organisms, including humans, microtubules serve a variety of important cellular functions, e.g. cell motility, cell division, the maintenance of cell shape, axonal transport and axon growth.The major component of microtubules, Lubulins are encoded by multigene families. We have studied tubulin isotypes in the simple nematode Caenorhabditis elegans, as the system is amenable to senelic, cellular, and molecular biological analyses. A number of monoclonal antibodies which recognize different isoforms of tubulins are identified and used to determine their cellular and molecular specificity. Like oilier complex higher organisms, the nematode has at least 12 isotypes that can be resolved on isoelctric focusing gels. Some of these isotypes are recognized by distinct monoclonal antibodies. Monoclonal antibody 6-11B-1 specifically recognizes the mechanosensory neurons, and McAb 2-28-33, is specific to GABAergic neurons in the nematode. A number of "uncoordinated" mutants with abnormal locomotion have been screened immunocytochemically, to identify genes affecting axonal growth and guidance in C. elegans. Finally, we have used the alpha and beta tubulin specific monoclonal antibodies to directly screen C. elegans _cDNA expression libraries to clone members of the tubulin gene family in C. elegans. The nucleotide sequence of an alpha tubulin reveals a novel trans-splicing signal sequence.These studies could lead to the understanding of the mechanisms by which functionally distinct microtubules are formed in higher organisms.