Trichomonas vaginalis: Chromatin and mitotic spindle during mitosis

The mitotic phases and the changes that the chromatin and mitotic microtubu les undergo during mitosis in the sexually transmitted parasite Trichomonas vaginalis are described. Parasites arrested in the gap 2 phase of the cell cycle by nutrient starvation were induced to mitosis by addition of fresh whole medium. [H-3] Thymidine labeling of trichomonad parasites for 24 h sh owed that parasites have at least four synchronic duplications after mitosi s induction. Fixed or live and acridine orange (AO)-stained trichomonads an alyzed at different times during mitosis by epifluorescence microscopy show ed that mitosis took about 45 min and is divided into five stages: prophase , metaphase, early and late anaphase, early and late telophase, and cytokin esis. The AO-stained nucleus of live trichomonads showed green (DNA) and or ange (RNA) fluorescence, and the nucleic acid nature was confirmed by DNase and RNase treatment, respectively. The chromatin appeared partially conden sed during interphase. At metaphase, it appeared as six condensed chromosom es, as recently reported, which decondensed at anaphase and migrated to the nuclear poles at telophase. In addition, small bundles of microtubules (as hemispindles) were detected only in metaphase with. the polyclonal antibod y anti-Entamoeba histolytica alpha -tubulin. This antibody showed that the hemispindle and an atractophore-like structure seem to duplicate and polari ze during metaphase. In conclusion, T. vaginalis mitosis involves five mito tic phases in which the chromatin undergoes different degrees of condensati on, from chromosomes to decondensed chromatin, and two hemispindles that ar e observed only in the metaphase stage. (C) 2000 Academic Press.