Mitosis in the Hemoflagellate Trypanosoma cyclops*

Abstract

The ultrastructure of interphase and mitotic nuclei of the epimastigote form of Trypanosoma cyclops Weinman is described. In the interphase nucleus the nucleolus is located centrally while at the periphery of the nucleus condensed chromatin is in contact with the nuclear envelope. The nucleolus fragments at the onset of mitosis, but granular material of presumptive nucleolar origin is often recognizable in the mitotic nucleus. Peripheral chromatin is in contact with the nuclear envelope throughout mitosis, and it seems reasonable to assume that the nuclear envelope is involved in its segregation to the daughter nuclei. Spindle microtubules extend between the poles of the dividing nucleus and terminate close to the nuclear envelope. The basal body and kinetoplast divide before the onset of mitosis and do not appear to have any morphologic involvement in that process. Spindle pole bodies, kinetochores, and chromosomal microtubules have not been observed.

Effect of topoisomerase inhibitors and DNA-binding drugs on the cell proliferation and ultrastructure of Trypanosoma cruzi

“…with rebeccamycin, showing that low drug concentrations were able to reduce cell proliferation by up to 95% [30,53]. In this work, treatment with topo I inhibitors promoted severe unpacking of the heterochromatin in interphase cells, which is usually observed surrounding the nucleolus and juxtaposed to the inner nuclear membrane [7,54]. Such ultrastructural alterations were also observed in T. cruzi epimastigotes exposed to ␥ radiation [55].…”

Architecture of the Trypanosoma brucei nucleus during interphase and mitosis

“…This is different from the situation in some trypanosomatids (e.g. Blastocrithidia, Trypanosoma cruzi) in which the nucleolus fragments or disperses during mitosis (De Souza and Meyer 1974;Heywood and Weinman 1978;Solari 1983) but similar to Leishmania ssp. In the euglenoids, a group of organisms closely related to trypanosomatids, the nucleolus also persists during mitosis.…”

Ultrastructural studies on mitosis in Trypanosoma danilewskyi (Mastigophora: Zoomastigophorea)

“…danilewskyi has an unusual process of cytokinesis, the essential stages of karyokinesis are as recorded for other Kinetoplastida (Heywood and Weinman 1978;Solari 1980Solari , 1983Souto-Padron et al 1980;Vickerman andPreston 1970, 1976): the nuclear membrane persists throughout mitosis, there is an intranuclear microtubular spindle, there are no observable polar structures which act as microtubular organizing centres, and dense plaques (kinetochores) are seen on the spindles. Mitosis in T .…”