title: Correlation between polyploidy and auxotrophic segregation in the imperfect yeast Candida albicans.
abstract: In order to clarify the relationship between polyploidization and the capability of phenotypic switching in the imperfect yeast Candida albicans, two types of variants were isolated as segregants from a fusant, which produced a proportion of the cell population with a higher ploidy than the rest, either in a temperature-dependent or -independent manner, when incubated at low (28 degrees C) and high (37 degrees C) temperatures. In the case of the temperature-dependent type of variants, high-ploidy cells appeared at 37 degrees C but rarely at 28 degrees C. This phenotype was named Pldts (temperature-sensitive polyploidization), and the temperature-independent phenotype was called Pld-. The appearance of high-ploidy cells in the culture of the Pldts strain at 37 degrees C was accompanied by a significant increase in the frequency of auxotrophic variants; these variants probably occur as a result of segregation of auxotrophic markers from the heterozygous to the homozygous state. Both Pldts and Pld- phenotypes were recessive in a fusion with a Pld+ parent. An adenine auxotrophic marker (ade1) was introduced into a Pldts strain in a heterozygous state, and the individual high-ploidy cells of this strain, grown at 37 degrees C, were micromanipulated to form colonies, which consisted of red and white sectors appearing at high frequency on a pink background. When the ade1 auxotrophy was introduced into Pld- strains, frequently sectored colonies were produced. These results suggested an increased level of chromosome missegregation in both types of Pld mutants. Analyses by pulsed-field gel electrophoresis of Ade-segregants, derived from a micromanipulated high-ploidy cell of a Pld(ts) strain, suggested the occurrence of nonreciprocal recombination, some of which includes chromosome loss.
authors.affiliation: Department of Biology, Faculty of Science, Nara Women's University, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Suzuki
authors.forename: A
authors.initials: A
authors.lastname: Hitomi
authors.forename: P T
authors.initials: PT
authors.lastname: Magee
authors.forename: S
authors.initials: S
authors.lastname: Sakaguchi
mesh_terms: D000225:Adenine / Q000378:metabolism; D002176:Candida albicans / Q000235:genetics* / Q000648:ultrastructure; D002459:Cell Fusion; D002467:Cell Nucleus / Q000648:ultrastructure; D005819:Genetic Markers; D016681:Genome, Fungal; D008957:Models, Genetic; D010641:Phenotype; D011003:Ploidies; D011123:Polyploidy; D008941:Spindle Apparatus / Q000648:ultrastructure
chemical_list: D005819:Genetic Markers; D000225:Adenine