title: Neurospora crassa cytoplasmic ribosomes: isolation and characterization of a cold-sensitive mutant defective in ribosome biosynthesis.
abstract: Twenty-seven cold-sensitive mutants of Neurospora crassa were isolated by mutagenesis of wild-type conidia followed by filtration enrichment in complete medium at the nonpermissive temperature (10 C). Zone sedimentation analyses of cytoplasmic ribosomes isolated from the wild-type strain and from 14 of the mutant strains grown at 10 C indicate that one cold-sensitive mutant is defective in ribosome biosynthesis at that temperature: instead of the 2.3:1 mass ratio of 60S:37S ribosomal subunits characteristic of wild type, the mutant strain PJ30201 (called crib-1 for cytoplasmic ribosome biosynthesis) exhibits a mass ratio of approximately 7.2:1. Ribosomal subunits synthesized by strain PJ30201 at 25 C are present in wild-type proportions. The cold-sensitive and ribosomal phenotypes segregate together in tetrads isolated from crosses between strain PJ30201 and the wild type indicating that a single nuclear gene mutation is probably responsible for both mutant phenotypes. The crib-1 locus lies near the centromere in linkage group IV.
mesh_terms: D002499:Centrifugation, Density Gradient; D002874:Chromosome Mapping; D003080:Cold Temperature; D003470:Culture Media; D005374:Filtration; D009154:Mutation; D009491:Neurospora / Q000648:ultrastructure*; D009492:Neurospora crassa / Q000254:growth & development / Q000302:isolation & purification / Q000648:ultrastructure*; D010641:Phenotype; D012270:Ribosomes / Q000032:analysis; D013395:Sucrose; D013997:Time Factors; D014316:Tritium; D014529:Uridine / Q000378:metabolism
chemical_list: D003470:Culture Media; D014316:Tritium; D013395:Sucrose; D014529:Uridine