Selection of Cells Defective in Pyrimidine (TK) and Purine (APRT and HPRT Salvage: Development of Host Strains Appropriate for Transfection

The usefulness of the purine and pyrimidine salvage pathways in the study of the mechanisms of mutation and in the selection of cell lines stably transformed by vectors expressing these genes is well documented. Unfortunately, many investigators are deterred from selecting new host strains deficient in these enzymes because of the difficulties inherent in isolating recessive mutations of autosomal genes. Furthermore, considerable suspicion was cast over somatic cell genetics by the so-called epigenetic nature of some phenotypic changes (1 ). However, given the clear molecular basis of the vast majority of mutant phenotypes, such apprehensions are largely unwarranted, provided that careful, clean selections are employed (e.g., see . 2 ).