THE MICROTUBULAR SYSTEM AND POSTTRANSLATIONALLY MODIFIED TUBULIN DURING SPERMATOGENESIS IN A PARASITIC NEMATODE WITH AMEBOID AND AFLAGELLATE SPERMATOZOA

Using transmission electron microscopy and immunologic approaches with various antibodies against general tubulin and posttranslationally mo dified tubulin, we investigated microtubule organization during sperma togenesis in Heligmasomoides polygyrus, a species in which a conspicuo us but transient microtubular system exists in several forms: a cytopl asmic network in the spermatocyte, the meiotic spindle, a perinuclear network and a longitudinal bundle of microtubules in the spermatid. Th is pattern differs from most nematodes including Caenorhabditis elegan s, in which spermatids have not microtubules. In the spermatozoon of H . polygyrus, immunocytochemistry does not detect tubulin, but electron microscopy reveals two centrioles with a unique structure of 10 singl ets. In male germ cells, microtubules are probably involved in cell sh aping and positioning of organelles but not in cell motility. In all t ransient tubulin structures described in spermatocytes and spermatids of H. polygyrus, detyrosination, tyrosination, and polyglutamylation w ere detected, but acetylation and polyglycylation were not. The presen ce/absence of these posttranslational modifications is apparently not stage dependent. This is the first study of posttranslationally modifi ed tubulin in nematode spermatogenesis. (C) 1998 Wiley-Liss, Inc.