title: The isolation and genetic characterization of extrachromosomal chloramphenicol and oligomycin-resistant mutants from the petite-negative yeast Kluyveromyces lactis.
abstract: Spontaneous mutants of the petite-negative yeast Kluyveromyces lactis, resistant to the antibiotics chloramphenicol and oligomycin, were isolated and genetically characterized. Three chloramphenicol-resistant mutants showed non-Mendelian inheritance when crossed to sensitive parents. Of 5 oligomycin-resistant strains studied, three exhibited resistance due to the presence of an extrachromosomal mutation. The resistance of the other two deriving from a nuclear and recessive mutation. When two factor crosses in trans configuration were performed between two of the chloramphenicol and the five oligomycin-resistant mutants a polarity in recombination was observed with a predominance of sensitive (OSCS) over resistant (ORCR) reciprocal recombinants. Allelism tests carried out among the oligomycin-resistant mutants indicated the presence of at least two distinct extrachromosomal regions responsible for the resistance.
mesh_terms: D002701:Chloramphenicol / Q000494:pharmacology*; D003433:Crosses, Genetic; D004352:Drug Resistance, Microbial; D005111:Extrachromosomal Inheritance; D009154:Mutation; D009840:Oligomycins / Q000494:pharmacology*; D010641:Phenotype; D015003:Yeasts / Q000187:drug effects
chemical_list: D009840:Oligomycins; D002701:Chloramphenicol