title: [Detection of concealed "illegitimate" nuclei in tetrad analysis of the diploid progeny of heterokaryons in Saccharomyces cerevisiae].
abstract: In this work, the studies on the previously detected phenomenon of concealed heterokaryosis in Saccharomyces cerevisiae were continued. In genetic and Southern blotting experiments, one of the nuclei in the heterokaryon was shown to be active (capable of division and ensuring the corresponding cell phenotype), whereas the other was not expressed until the heterokaryotic clone was transferred to the medium selective for this concealed nucleus. Moreover, the concealed nucleus was able to assume the active state after fusion with the second parental nucleus. It was analyzed whether the nuclei with new marker combinations occurring in meiosis can behave as exceptional nuclei. Tetrad analysis of hybrids carrying the kar1 mutation in their nuclei revealed the relatively high percentage of exceptional tetrads (more than 10%). One spore in these tetrads usually formed diploid cells capable of sporulation. The presented data of genetic and molecular biological studies testify in favor of the assumption that abnormal spores contain two nuclei, which form an "illegitimate" hybrid after fusion. An extraneous spore (termed x) has usually a genotype close to that of one of the spores in this tetrad. Thus, it was assumed that the additional DNA replication round occurs in the absence of cell division during one of meiotic divisions. Results of cytological analysis conducted by the method of specific DNA staining confirmed the existence of exceptional tetrads, one spore of which contains two nuclei.
authors.affiliation: Institute of Cytology, Russian Academy of Sciences, St. Petersburg, 194064 Russia.
authors.forename: O V
authors.initials: OV
authors.lastname: Nevzgliadova
authors.forename: A A
authors.initials: AA
authors.lastname: Gaĭvoronskiĭ
authors.forename: A V
authors.initials: AV
authors.lastname: Artemov
authors.forename: T I
authors.initials: TI
authors.lastname: Smirnova
authors.forename: T R
authors.initials: TR
authors.lastname: Soĭdla
mesh_terms: D002467:Cell Nucleus / Q000235:genetics* / Q000648:ultrastructure; D004261:DNA Replication; D004271:DNA, Fungal / Q000032:analysis / Q000235:genetics*; D004171:Diploidy; D005656:Fungal Proteins / Q000235:genetics; D009154:Mutation; D009687:Nuclear Proteins / Q000235:genetics; D012441:Saccharomyces cerevisiae / Q000235:genetics* / Q000254:growth & development / Q000648:ultrastructure; D029701:Saccharomyces cerevisiae Proteins
chemical_list: D004271:DNA, Fungal; D005656:Fungal Proteins; C074559:KAR1 protein, S cerevisiae; D009687:Nuclear Proteins; D029701:Saccharomyces cerevisiae Proteins
vernacular_title: Vyiavlenie skrytykh "nezakonnykh" iaderpri tetradnom analize diploidnogo potomstva geterokarionov u Saccharomyces cerevisiae.