GAMMA-TUBULIN IS PERMANENTLY ASSOCIATED WITH BASAL BODIES IN CILIATES

Ciliates are of special interest owing to the multiplicity and diversi ty of their microtubule organizing centers (MTOCs). The subcellular lo calization of gamma-tubulin in these protozoa has not been extensively studied. The cloning of a gamma-tubulin gene in Euplotes (Liang, A., K. Heckmann, Gene 135, 319-322 (1993)) led us to examine the localizat ion of this protein. We used three polyclonal antibodies, JH46, R58 an d R70. They had been raised against peptides common to mammalian and A spergillus gamma-tubulins. These regions had 69 %, 95 %, and 75 % iden tity with the corresponding regions of Euplotes gamma-tubulin. Immunob lotting (R70) revealed a polypeptide corresponding to the molecular ma ss of Euplotes gamma-tubulin. In Euplotes octocarinatus, gamma-tubulin was detected by immunofluorescence (R70) in the basal bodies, the mic ronucleus and the macronucleus throughout the cell cycle. The presence of gamma-tubulin in basal bodies and micronuclei was confirmed with t he other two antibodies JH46 and R58. The permanent association of gam ma-tubulin with basal bodies was also observed in Tetrahymena thermoph ila and Paramecium tetraurelia, two ciliates distantly related to Eupl otes. These results not only extend to ciliates the finding that gamma -tubulin is permanently associated with ciliary basal bodies, but also demonstrate that gamma-tubulin is present in unconventional MTOCs.