The Microtubular System and Posttranslationally Modified Tubulin During Spermatogenesis in a Parasitic Nematode With Amoeboid

ABSTRACT Using transmission electron mi-croscopy and immunologic approaches with various antibodies against general tubulin and posttranslation-ally modified tubulin, we investigated microtubule orga-nization during spermatogenesis in Heligmosomoides polygyrus, a species in which a conspicuous but transient microtubular system exists in several forms: a cytoplasmic network in the spermatocyte, the meiotic spindle, a perinuclear network and a longitudinal bundle of microtubules in the spermatid. This pattern differs from most nematodes including Caenorhabditis el-egans, in which spermatids have not microtubules. In the spermatozoon of H. polygyrus, immunocytochemis-try does not detect tubulin, but electron microscopy reveals two centrioles with a unique structure of 10 singlets. In male germ cells, microtubules are probably involved in cell shaping and positioning of organelles but not in cell motility. In all transient tubulin structures described in spermatocytes and spermatids of H. polygyrus, detyrosination, tyrosination, and polyglutam-ylation were detected, but acetylation and polyglycyla-tion were not. The presence/absence of these posttrans-lational modifications is apparently not stage dependent. This is the first study of posttranslationally modified tubulin in nematode spermatogenesis. Mol. Reprod