[The effect of the Mycoplasma contamination of 2 kidney cell sublines from the kangaroo rat on their karyotypic structure].

The karyotypic variability has been investigated for two cell sublines of Rat kangaroo kidney cultured for 40-160 days after contamination with Acholeplasma laidlawii, strain PG-8. The contaminated cultures did not differ from non-contaminated ones in cell distribution for chromosome number. The majority of cells of subline NBL-3-11 with modal number of chromosomes displayed the main structural variant of the karyotype (SVK)--2+2+2+2+2+1; in subline NBL-3-17 the main SVK being 3+3+3+3+3+2. A comparison of intact cultures of these sublines in cell distribution for chromosome number show just the opposite direction of aneuploidy processes: cell heterogeneity for chromosome number decreased in NBL-3-11 and increased in NBL-3-17. The quantity of chromosomal aberrations, primarily chromosomal breaks, increases within 40-160 days of cultivation of contaminated cells of subline NBL-3-11. The number of chromosomal aberrations, mainly at the expense of dicentrics due to telomeric associations, increases after 40 days of cultivation of subline NBL-3-17 contaminated cells. During a long-term cultivation (110 days) of subline NBL-3-17 intact cells, there is an increase in the number of chromosomal aberrations, mainly dicentrics, whereas the extent of chromosomal breaks appears much less. The present results and other additional experimental data make it possible to suppose that the increase in chromosomal instability seen in subline NBL-3-17 at a long-term cultivation may be characteristic of this culture, in distinction to subline NBL-3-11. The most frequent breaks were seen in chromosomes 1, 2 and X of intact and contaminated cells in both the sublines. Chromosomes 1, 2 and 4 are mainly involved in dicentric formations by q (long) arms. The role of dicentrics in cell adaptation to in vitro conditions is discussed.