Ref ID : 7669
Simone Eperon and Gerard de Haller; [Effet de la Vinblastine sur le Trophozoite et la Bipartition de Thuricola folliculata (O.F. Muller, 1786) (Ciliophora, Peritrichida), en Particulier sur le Micronoyau]. Protistologica XVIII(1):85-102, 1982
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The first purpose of this study is to show that Thuricola folliculata reacts to vinblastine (VB), mitoclastic agent, as other cellular types do. Secondary, ultrastructural effects of this inhibitor are seen in this Ciliate which seems to be a good material because of its numerous microtubules (Mt). The substance has the advantage to precipitate tubulin into crystals. Macroscopical effect of VB is observed in vivo with a light microscope at different stages of the animal's asexual cycle. Ultrastructural effets are studied with a transmission electron microscope. The interfission and the first fission stages are blocked by VB that nevertheless has no effect upon following division stages. Vinblastine yields two ultrastructural results: 1) microtubules of the cytopharynx, cilia and kinetosomes are generally resistant to VB; micronuclear fusorial Mt are destroyed and tubulin crystals appear; 2) the cell has a tubulin pool that is concentrated in the oral cytoplasmic region before fission and in the micronucleus at beginning of division. Four deductions result from this work: 1) the point where 50 percent of the cell become insensitive to 8.8x10E(-5) M of VB is located just before cytokinesis. 2) Microtubules with different functions vary in their lability degree; tubulin pools seem to be required for stomatogenesis preparation and for spindle construction. 3) The Mt stability is dependent of the turnover rate and of the presence of microtubule-associated proteins (MAPs). 4) The vinblastine inhibits micronuclear mitosis and also cytokinesis; we may therefore advance the hypothesis that VB acts not only on micronuclear tubulins but also perhaps on actin-like proteins that are involved in the cytokinesis.