title: Acquisition of chick cytosol thymidine kinase activity by thymidine kinase-deficient mouse fibroblast cells after fusion with chick erythrocytes.
abstract: Chick-mouse heterokaryons were obtained by UV-Sendai virus-induced fusion of chick erythrocytes with thymidine (dT) kinase-deficient mouse fibroblast [LM(TK(-))] cells. Autoradiographic studies demonstrated that 1 day after fusion, [(3)H]dT was incorporated into both red blood cell and LM(TK(-)) nuclei of 23% of the heterokaryons. Self-fused LM(TK(-)) cells failed to incorporate [(3)H]dT into nuclear DNA. 15 clonal lines of chick-mouse somatic cell hybrids [LM(TK(-))/CRB] were isolated from the heterokaryons by cultivating them in selective hypoxanthine-aminopterin-thymidine-glycine medium. LM(TK(-)) and chick erythrocytes exhibited little, if any, cytosol dT kinase activity. In contrast, all 15 LM(TK(-))/CRB lines contained levels of cytosol dT kinase activity comparable to that found in chick embryo cells. Disk polyacrylamide gel electrophoresis and isoelectric focusing analyses demonstrated that the LM(TK(-))/CRB cells contained chick cytosol, but not mouse cytosol dT kinase. The LM(TK(-))/CRB cells also contained mouse mitochondrial, but not chick mitochondrial dT kinase. Hence, the clonal lines were somatic cell hybrids and not LM(TK(-)) cell revertants. The experiments demonstrate that chick erythrocyte cytosol dT kinase can be activated in heterokaryons and in hybrid cells, most likely as a result of functions supplied by mouse fibroblast cells.
mesh_terms: D000818:Animals; D002459:Cell Fusion; D002460:Cell Line; D002471:Cell Transformation, Neoplastic; D002499:Centrifugation, Density Gradient; D002642:Chick Embryo; D002645:Chickens; D003470:Culture Media; D003600:Cytosol / Q000201:enzymology; D004589:Electrophoresis, Disc; D004912:Erythrocytes / Q000201:enzymology*; D005347:Fibroblasts / Q000201:enzymology*; D006822:Hybrid Cells; D007525:Isoelectric Focusing; D008928:Mitochondria / Q000201:enzymology; D010222:Parainfluenza Virus 1, Human / Q000528:radiation effects; D011830:Radiation Effects; D013936:Thymidine; D013937:Thymidine Kinase / Q000302:isolation & purification / Q000378:metabolism*; D013997:Time Factors; D014316:Tritium; D014466:Ultraviolet Rays
chemical_list: D003470:Culture Media; D014316:Tritium; D013937:Thymidine Kinase; D013936:Thymidine