title: Thymidine kinase-deficient mutants of Physarum polycephalum; relationships between enzyme activity levels and ploidy.
abstract: Thymidine (TK) and deoxycytidine (dCK) kinase levels, chromosome counts and whole culture protein:DNA ratios have been determined in the TK- plasmodial strains of P. polycephalum--TU84 and TU63--and on several wild type (wt) plasmodial and amoebal strains from Wis 1 and Colonia backgrounds. It was found that (a) dCK levels and protein:DNA ratios were similar in all plasmodia, regardless of ploidy or genetic background; (b) TU84 and 63 were haploid; (c) TK specific activity was similar in all wt plasmodia but lower in amoebae; (d) TK activities of mutants and wt were approximately additive in heterokaryons. It was concluded that TK deficiency is due to a defect in a structural gene and that wt strains are TK+/TK+ and mutants hemizygous TK-.
mesh_terms: D000483:Alleles; D004247:DNA / Q000378:metabolism; D003842:Deoxycytidine Kinase / Q000235:genetics; D004171:Diploidy; D006238:Haploidy; D006822:Hybrid Cells / Q000378:metabolism; D009154:Mutation; D010804:Physarum / Q000235:genetics*; D011506:Proteins / Q000378:metabolism; D013937:Thymidine Kinase / Q000172:deficiency / Q000235:genetics* / Q000378:metabolism
chemical_list: D011506:Proteins; D004247:DNA; D013937:Thymidine Kinase; D003842:Deoxycytidine Kinase