title: [Extrachromosomal DNA in yeast-Saccharomyces].
abstract: The recombinant plasmids containing autonomously replicating sequence (ARS) of yeast rDNA repeat are characterized by a high instability in transformed yeast cells. The instability of chimaric plasmids in yeast may result from improper replication and/or irregular mitotic segregation. To study the replication properties alone we have constructed series of hybrid plasmids containing centromeric DNA (CEN3), a selective marker (leu2) and ARS of rDNA. Each of these plasmids with the functional centromere should exhibit chromosomal i. e. regular type of mitotic segregation. The study of mitotic segregation of constructed plasmids has shown that the ARS rDNA from yeast is distinguished from other ARSs described in literature: ARS1, ARS2, ARS o-micron DNA. 1. The activation of replication of ARS rDNA is accidental, i. e. probability of ARS rDNA in the cell cycle is much less than one. 2. Some nuclear mutations as well as rho- mutation result in the increase of replicative activity of ARS rDNA. In some yeast strains the activity of ARS rDNA can reach the activity of ARS1, i. e. was close to one. The features of ARS rDNA may account for the phenomenon of amplification of rDNA genes.
mesh_terms: D004247:DNA / Q000235:genetics*; D004261:DNA Replication; D004271:DNA, Fungal / Q000235:genetics; D004274:DNA, Recombinant / Q000378:metabolism; D004275:DNA, Ribosomal; D005784:Gene Amplification; D009154:Mutation; D010957:Plasmids; D012441:Saccharomyces cerevisiae / Q000235:genetics*
chemical_list: D004271:DNA, Fungal; D004274:DNA, Recombinant; D004275:DNA, Ribosomal; D004247:DNA
vernacular_title: Issledovanie vnekhromosomnoĭ DNK u drozhzheĭ-Sakharomitsetov.