| Abstract: | The frequency of the YEp13, pEF91, YEp13 + HBs, pNMVG3954 plasmids' elimination in a series of isogenic strains n. 2n and 3n was studied. Plasmid stability and the level of expression of the gene of hepatitis B surface antigen (HBsAg) increased in polyploid transformants as a result of increase in plasmid copy number. Heterozygotes MATa/MAT differed from the homozygotes in higher stability of YEp13, pEF91, and YEp13 + HBs plasmids having the same quantity of the HBsAg antigen. The appearance of negative properties--destabilization of episomal plasmids or decrease in synthesis of heterologous protein have been discovered in certain diploid cell. These results point to limitations in constructing a polyploid producer on the basis of the similar type of genome. |
