ACETYLATED ALPHA-TUBULIN IN THE CONNECTING CILIUM OF DEVELOPING RAT PHOTORECEPTORS

Purpose. To examine the distribution of acetylated alpha-tubulin in th e connecting cilium of rat rod photoreceptors during different stages of photoreceptor development. Methods. An antibody found to be specifi c for the acetylated form of alpha-tubulin was used in immunoelectron microscopy of retinas from animals of different ages. Results. All the microtubules of the connecting cilium, including those of the basal b odies, were found to contain acetylated alpha-tubulin at the earliest stage of outer segment development, before the cilium has begun to gro w out from the cell, and at all subsequent stages. Conclusions. These results indicate that the alpha-tubulin of the connecting cilium is ac etylated either before, or at least very soon after, its assembly into microtubules. Given that acetylation of alpha-tubulin is correlated w ith stable microtubules, the results suggest that stable microtubules might be important in creating the foundation for the formation of the outer segment, as well as in helping maintain the polarity of the mat ure photoreceptor.