Abstract
Linkage relationships among loci conferring resistances to neomycin-kanamycin (nek), vio-mycin-capreomycin (vic) and streptomycin (str), as well as auxotrophic markers, were analyzed employing the conjugation system of Mycobacterium smegmatis strains Rabinowitchi and PM5. Nek and vic loci were found to be closely linked to each other and also linked to argA-6 and argB-1. No linkage was observed between str and nek or vic. The locations of other loci, met-5, his-13 and leu-11, also could not be determined. In certain recombinant types, nek and vic alleles formed stable hetero-genotes. When nekr and neks or vicr and vics alleles existed in one cell, sensitivity to those drugs was dominant over resistance. Segregants of nekr or vicr from the heterogenotes were detected at a fre-quency of about 10-4 to 10-5. Such a stable heterogenote was not detected in str allele.
