title: Complementation analysis with new genetic markers in Phaffia rhodozyma.
abstract: Isolation and characterization of auxotrophic mutants from wild-type and astaxanthin mutant strains of Phaffia rhodozyma is described. Differences in survival were observed when u.v. irradiation of P. rhodozyma wild-type and astaxanthin mutant strains were incubated in the dark or exposed to photoreactivating light. Ultra-violet mutagenesis was not effective to produce auxotrophic mutants in this yeast. Auxotrophic mutants were obtained with high efficiency through a nystatin enrichment procedure after a N-methyl-N'-nitro-N-nitrosoguanidine (NGT) mutagenic treatment with a 0.12% survivor level. Stringent mutagenetic conditions were needed to obtain P. rhodozyma auxotrophs. The most frequent mutants were ade- and met- in a rather narrow auxotroph spectrum. These results may be associated with a possible diploid condition of this yeast. The high number of adenine auxotrophs obtained in relation to other auxotrophic mutants suggests the possibility of some degree of heterozygosity in the wild-type strain UCD 67-385.
authors.affiliation: Laboratorio de Genética, Facultad de Ciencias, Universidad de Chile, Santiago, Chile.
authors.forename: P
authors.initials: P
authors.lastname: Retamales
authors.forename: R
authors.initials: R
authors.lastname: León
authors.forename: C
authors.initials: C
authors.lastname: Martínez
authors.forename: G
authors.initials: G
authors.lastname: Hermosilla
authors.forename: G
authors.initials: G
authors.lastname: Pincheira
authors.forename: V
authors.initials: V
authors.lastname: Cifuentes
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology; D000935:Antifungal Agents / Q000494:pharmacology; D005816:Genetic Complementation Test; D005819:Genetic Markers; D008027:Light; D003904:Mitosporic Fungi / Q000235:genetics* / Q000378:metabolism / Q000528:radiation effects; D016296:Mutagenesis; D009761:Nystatin / Q000494:pharmacology; D014466:Ultraviolet Rays; D024341:Xanthophylls; D015003:Yeasts / Q000235:genetics* / Q000378:metabolism / Q000528:radiation effects; D019207:beta Carotene / Q000031:analogs & derivatives* / Q000096:biosynthesis
chemical_list: D000900:Anti-Bacterial Agents; D000935:Antifungal Agents; D005819:Genetic Markers; D024341:Xanthophylls; D019207:beta Carotene; D009761:Nystatin; C005948:astaxanthine