[Hybridization of Chinese hamster cells sensitive to ultraviolet irradiation]

Resistance to UV-light was studied in two UV-sensitive aneuploid Chinese hamster cell clones to different origin and degree of sensitivity, their respective polyploids and somatic cell hybrids. The karyotype of the parental clones, cell hybrids and polyploids was analyzed in parallel. A great variability of karyotypes was detected in hybrid cells. Serial cultivation of hybrids was accompanied by chromosome loss. Soon after fusion the hybrid clones proved to be more resistant to UV than the parental sensitive cells. However, their sensitivity increased with passages. The comparison of UV-sensitivity with data on karyotype analysis allowed to assume that the increase in sensitivity was correlated with the loss of particular chromosomes or chromosome regions. The results obtained indicated the existence of a polygenic control of UV-sensitivity, the multiple genes being assigned to different chromosomes. A reverse effect of ploidy was detected, i.e. a decrease in the resistance to the lethal action of UV-light in polyploids as compared to the parental clones.