THE INFLUENCE OF MYCOPLASMA SALIVARIUM IN THE ABSENCE
AND PRESENCE OF L-ARGININE ON KARYOTYPIC VARIABILITY IN CELL LINE
OF THE INDIAN MUNTJAK SKIN FIBROBLASTS UNDER LONG-TERN CULTIVATION
G. G. Poljanskaya, T. N. Efremova
Institute of Cytology RAS, St. Petersburg;
e-mail: poljansk@mail.cytspb.rssi.ru
The influence of Mycoplasma salivarium on the numerical and structural karyotypic variability has been investigated
in the «markerless» cell line of the Indian muntjak skin fibroblasts (line M) during long-term cultivation
in the absence and presence of L-arginine. Cultivation of the mycoplasmal contaminated cells for 15 and
30 days did not change the character of cell distribution for the chromosome number. In the contaminated cells
cultivated for 60 and 75 days, the character of cell distribution for the chromosome number was changed. These
changes involved bimodal distribution for the chromosome number due to a significant decrease in the frequency
of the cells with the modal number of chromosomes with main structural variant of karyotype (SVK) —
2 + 2 + 1 + 1 + 1 and an increase in the frequency of cells with submodal number of chromosomes with main
SVK—2 + 2 + 1 + 1. Besides, a significant increase in the frequency of the cells with lower chromosome number
was observed in 60 days compared to that in 75 days of cultivation. Cultivation of the contaminated and control
cells in the medium with increased concentration of L-arginine during 60 days did not change the numerical
parameters relative to the control. Cultivation of the contaminated cells for 60 days followed by addition of
L-arginine for 15 days restored the numerical parameters the numerical parameters to the control level. In the
contaminated cells the frequency of chromosomal aberrations significantly increased for 30, 60 and 75 days cultivation
relative to the control variant. In 30 days, the small but significant increase took place due to increase in
the frequency of chromosomal aberrations of all the types. In 60 and 75 days, a greater increase took place due
to a significant increase in the frequency of chromosomal and chromatid breaks. Moreover, in 60 days, the level
of dicentrics (telomeric associations) mainly produced by chromosomes 1 and 2 increased significantly. The role
of dicentrics as one of the ways for adaptation of the «markerless» cell lines to condition of cultivation and the
role of L-arginine in the restoration of normal karyotypic structure of cell population of line M under mycoplasmal
contamination are discussed.
Key words: karyotypic variability, mycoplasmal contamination, L-arginine, chromosomal aberrations, dicentrics
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