Biochemical genetic studies of cycloheximide resistance in Neurospora crassa.

Genetic analysis of a number of cycloheximide-resistant mutants of Neurospora crassa has shown that resistance is controlled by several genes. Two of these appear to be located on linkage group V. Resistance to the antibiotic is dominant in wild-type-mutant heterokaryons. Two types of cycloheximide-resistant mutants were isolated: one type exhibited colonial morphology only when grown in the presence of cycloheximide and the other type maintained normal morphology even at high concentrations of the antibiotic. Reconstitution experiments with supernatant solutions and 80S monosomes prepared from wild-type and resistant mutant strains indicated that the property of cycloheximide resistance most likely is associated with the ribosomes. No electrophoretic or serological differences were found between the ribosomal proteins of the wild-type and resistant mutants.