Effect of Mycoplasma salivarium with and without L-arginine on karyotypic variability in cell line of Indian muntjac skin fibroblasts at long-term cultivation

Abstract

The effect of Mycoplasma salivarium on the numerical and structural karyotypic variability was studied in the markerless cell line of Indian muntjac skin fibroblasts (line M) during long-term cultivation with and without L-arginine. The cultivation of mycoplasma-contaminated cells for 15 and 30 days did not change the character of cell distribution for the number of chromosomes. In contaminated cells cultivated for 60 and 75 days, the character of cell distribution for the chromosome number changed. These changes involve bimodal distribution for the chromosome number due to a significant decrease in frequency of the cells with the modal number of chromosomes with the main structural variant of karyotype (SVK) 2 + 2 + 1 + 1 + 1 and an increase in the frequency of cells with the submodal number of chromosomes with a main SVK of 2 + 2 + 1 + 1. Furthermore, a significant increase in the frequency of cells with lower numbers of chromosomes was observed after 60 days compared to that after 75 days of cultivation. After the cultivation of the contaminated and control cells in the medium with an elevated concentration of L-arginine for 60 days, the numerical parameters were unchanged relative to the control. The cultivation of contaminated cells for 60 days followed by the addition of L-arginine for 15 days restored the numerical parameters to the control level. In the contaminated cells, the frequency of chromosomal aberrations for 30, 60, and 75 days increased significantly compared to the control variant. After 30 days of cultivation, a small but statistically significant increase took place due to a uniform slight increase in the frequency of chromosomal aberrations of all types. After 60 and 75 days, a greater increase occurred due to a statistically significant increase in the frequency of chromosomal and chromatid breaks. Moreover, after 60 days, the level of dicentrics (telomeric associations) mainly produced by chromosomes 1 and 2 increased significantly. The role of dicentrics as for a means of adaptation for markerless cell lines to the condition of cultivation and the role of L-arginine in the restoration of the normal karyotypic structure of the line M cell population at mycoplasmal contamination are discussed.