title: X-linkage of a human genetic locus that corrects the DNA synthesis lesion in tsC1AGOH mouse cells.
abstract: GM 126 diploid fibroblasts were fused with a heat-sensitive mouse cell mutant defective in DNA synthesis, and primary hybrids were selected at permissive and nonpermissive temperatures in HAT medium. Primary hybrids, primary hybrid clones back-selected in 8-azaguanine at the permissive temperature, and subclones of heat-resistant primary hybrids isolated under nonselective conditions or after 8-azaguanine treatment were tested for heat sensitivity, the expression of 26 human enzymes assigned to 19 different human chromosomes, and the presence of human chromosomes. Only the human X chromosome and X-linked marker enzymes exhibited a clear pattern of concordant segregation with the heat-resistant phenotype. On the basis of these observations, we have defined the human genetic locus that corrects the heat-sensitive lesion in tsC1AGOH as hrC1AGOH and have assigned this locus to the X chromosome. This observation provides the first instance where two selectable markers (heat resistance and 8-azaguanine sensitivity) are found on a single human chromosome and suggests that these markers may prove to be a valuable push-pull selective system of use in determining the linear arrangement of genes on human chromosomes by somatic cell genetics.
mesh_terms: D000818:Animals; D002460:Cell Line; D002874:Chromosome Mapping; D004247:DNA / Q000096:biosynthesis*; D005260:Female; D005796:Genes; D005819:Genetic Markers; D006358:Hot Temperature; D006801:Humans; D006822:Hybrid Cells / Q000378:metabolism*; D051379:Mice; D010641:Phenotype; D012730:Sex Chromosomes; D014960:X Chromosome
chemical_list: D005819:Genetic Markers; D004247:DNA