CHROMATIN ORGANIZATION IN CELL CYCLE OF AMOEBA PROTEUS ACCORDING TO OPTICAL TOMOGRAPHY DATA
S.Yu. Demin, M.A. Berdieva, Yu.I. Podlipaeva, A.L. Yudin, A.V. Goodkov 1
Institute of Cytology RAS, St. Petersburg, 194064;
1 e-mail: pelgood1@gmail.com
For the first time the nuclear cycle of large freshwater amoeba Amoeba proteus was studied by the method of optical tomography. The nuclei were fixed in situ
in the cells of synchronized culture, stained by DAPI and examined by confocal laser scanning microscope. 3D-images of intranuclear chromatin were studied in details at different
stages of nuclear cycle. The obtained data, together with literary ones allow represent the dynamics of structural organization of the nucleus in Amoeba proteus cell cycle in
a new fashion. It was concluded that in this species the two-stage interphase takes place, as well as mitosis of peculiar type which does not correspond to any known type of
mitosis according to classification existing now. It is presumed that in the course of nuclear cycle the chromosomes and/or their fragments are amplified, this presumption being in a
good correspondence with the data about nuclear DNA hyperreplication in the cell cycle of A. proteus. As a result of chromosomes amplification their number may vary at
different stages of cell cycle, and it allows to explain the contradictory data concerning the exact number of chromosomes in this species. The elimination of extra-DNA occurs
mainly at the stage between prophase and prometaphase. We presume the majority of chromosomes, or may be even all of them to be referred to cholocentric type according to
their behaviour during the mitosis.
Key words:
Amoeba proteus, nuclear cycle, confocal microscopy, optical tomography, chromatin organization
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