Entamoeba histolytica: ultrastructure of the chromosomes and the mitotic spindle

Experimental Parasitology
Bibiana Chávez-MunguíaAdolfo Martínez-Palomo

Abstract

We have analyzed by transmission electron microscopy the mitotic process of Entamoeba histolytica trophozoites in an asynchronous population of axenically cultured parasites. Our observations showed that nuclear microtubules, initially located at random in the karyosome during prophase, formed in subsequent stages a mitotic spindle closely related to the nuclear membrane at the polar regions of dividing nuclei. In late prophase and in anaphase, chromosomes appeared as dense bodies 0.1-0.5 microm. At least 15 chromosomes appeared in favorable planes of section, arranged as an incomplete elliptical circle, in close contact with microtubules. There was no morphological evidence of structures resembling the kinetochores of higher eukaryotes. When cut in cross-section, the mitotic spindle was made of 28-35 microtubular rosette assemblies. The latter probably correspond to a similar number of chromosomes, as has been shown by others with pulse-field electrophoresis and fluorescence microscopy of trophozoite spreads. In turn, each microtubular rosette was constituted by 7-12 parallel microtubules. In later stages of the metaphase, two sets of chromosomes were disposed forming a pair of elliptical circles. An additional finding in the ...Continue Reading

Citations

Sep 18, 2007·Experimental Parasitology·Bibiana Chávez-MunguíaAdolfo Martínez-Palomo
Jun 20, 2015·BioMed Research International·Guillermo Ortíz-EstradaMireya de la Garza
May 10, 2016·Experimental Parasitology·Eduardo Gómez-CondeÁlvaro José Montiel-Jarquín
Dec 12, 2019·Frontiers in Cellular and Infection Microbiology·Tansy C Hammarton

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