TAM selection of Drosophila somatic cell hybrids.

The selection of MDR3, an adenine-salvage-deficient variant of the Kc line, is described. It is resistant to methylpurine and to diaminopurine and is TAM (thymidine, adenine, methotrexate) sensitive. Two wild-type (TAM-resistant) cell lines, Schneider's line 3 (S3) and Dübendorfer's line 1 (D1), due to their different nutritional requirements, are unable to proliferate in medium ZH1% used for line MDR3. This allowed the selection of hybrids between MDR3 and either D1 or S3 in TAM cloning medium after treatment with polyethyleneglycol. Hybrids were identified by the isoenzyme pattern of NADP-dependent isocitrate dehydrogenase.