SELECTIVE EXPRESSION OF THE TBA-1 ALPHA-TUBULIN GENE IN A SET OF MECHANOSENSORY AND MOTOR-NEURONS DURING THE DEVELOPMENT OF CAENORHABDITIS-ELEGANS

In the nematode Caenorhabditis elegans, a monoclonal antibody 3A5 rais ed against Drosophila alpha tubulins selectively stains the nervous sy stem immuno-cytochemically. Direct screening of a C. elegans cDNA expr ession library with 3A5 has allowed cloning of the tba-1 (tubulin alph a-1) gene from C. elegans. The corresponding genomic DNA encodes a pro tein of 449 amino acid residues that has a high homology with the vert ebrate a: tubulins but a lower homology with yeast a tubulins. Interes tingly, the carboxyl-terminus sequence EEEGEEY (Glu-Glu-Glu-Gly-Glu-Gl u-Tyr) of the nematode tba-1 encoded isotype is identical to these res idues in human, mouse, rat, pig and chicken alpha-1 tubulin isotypes t hat are expressed in the brain. Temporal and spatial expression studie s of the tba-1 gene using Northern blot analysis and tba-1::lacZ fusio n gene expression analysis during embryonic and the postembryonic deve lopment of C. elegans reveal that the tba-1 tubulin is preferentially expressed in the nematode nervous system, especially in a set of mecha nosensory neurons and a set of ventral cord motor neurons (DA, DB, VA, and VB) during embryonic and postembryonic development. Our results i ndicate an inter-species conservation of the alpha tubulin carboxyl-te rminal domain in functionally related brain specific isotypes from met azoans as divergent as mammals and nematodes. These results also sugge st specificity of the individual alpha tubulin isotypes during neural development.