Biomaterial Database

Identification of autonomously replicating circular subtelomeric Y' elements in Saccharomyces cerevisiae. 1985

H Horowitz, and J E Haber

We marked a large number of yeast telomeres within their Y' regions by transforming strains with a fragment of Y' DNA into which the URA3 gene had been inserted. A few of the Ura+ transformants obtained were very unstable and were found to contain autonomously replicating URA3-marked circular Y' elements in high copy number. These marked extrachromosomal circles were capable of reintegrating into the chromosome at other telomeric locations. In contrast, most of the Ura+ transformants obtained were quite stable mitotically and were marked at bona fide chromosomal ends. These stable transformants gave rise to mitotically unstable URA3-marked circular Y' elements at a low frequency (up to 2.5%). The likelihood that such excisions and integrations represent a natural process in Saccharomyces cerevisiae is supported by our identification of putative Y' circles in untransformed strains. The transfer of Y' information among telomeres via a circular intermediate may be important for homogenizing the sequences at the ends of yeast chromosomes and for generating the frequent telomeric rearrangements that have been observed in S. cerevisiae.

UI	MeSH Term	Description	Entries
D008540	Meiosis	A type of CELL NUCLEUS division, occurring during maturation of the GERM CELLS. Two successive cell nucleus divisions following a single chromosome duplication (S PHASE) result in daughter cells with half the number of CHROMOSOMES as the parent cells.	M Phase, Meiotic,Meiotic M Phase,M Phases, Meiotic,Meioses,Meiotic M Phases,Phase, Meiotic M,Phases, Meiotic M
D008938	Mitosis	A type of CELL NUCLEUS division by means of which the two daughter nuclei normally receive identical complements of the number of CHROMOSOMES of the somatic cells of the species.	M Phase, Mitotic,Mitotic M Phase,M Phases, Mitotic,Mitoses,Mitotic M Phases,Phase, Mitotic M,Phases, Mitotic M
D012093	Replicon	Any DNA sequence capable of independent replication or a molecule that possesses a REPLICATION ORIGIN and which is therefore potentially capable of being replicated in a suitable cell. (Singleton & Sainsbury, Dictionary of Microbiology and Molecular Biology, 2d ed)	Replication Unit,Replication Units,Replicons,Unit, Replication,Units, Replication
D002875	Chromosomes	In a prokaryotic cell or in the nucleus of a eukaryotic cell, a structure consisting of or containing DNA which carries the genetic information essential to the cell. (From Singleton & Sainsbury, Dictionary of Microbiology and Molecular Biology, 2d ed)	Chromosome
D004261	DNA Replication	The process by which a DNA molecule is duplicated.	Autonomous Replication,Replication, Autonomous,Autonomous Replications,DNA Replications,Replication, DNA,Replications, Autonomous,Replications, DNA
D004270	DNA, Circular	Any of the covalently closed DNA molecules found in bacteria, many viruses, mitochondria, plastids, and plasmids. Small, polydisperse circular DNA's have also been observed in a number of eukaryotic organisms and are suggested to have homology with chromosomal DNA and the capacity to be inserted into, and excised from, chromosomal DNA. It is a fragment of DNA formed by a process of looping out and deletion, containing a constant region of the mu heavy chain and the 3'-part of the mu switch region. Circular DNA is a normal product of rearrangement among gene segments encoding the variable regions of immunoglobulin light and heavy chains, as well as the T-cell receptor. (Riger et al., Glossary of Genetics, 5th ed & Segen, Dictionary of Modern Medicine, 1992)	Circular DNA,Circular DNAs,DNAs, Circular
D004271	DNA, Fungal	Deoxyribonucleic acid that makes up the genetic material of fungi.	Fungal DNA
D005111	Extrachromosomal Inheritance	Vertical transmission of hereditary characters by DNA from cytoplasmic organelles such as MITOCHONDRIA; CHLOROPLASTS; and PLASTIDS, or from PLASMIDS or viral episomal DNA.	Cytoplasmic Inheritance,Extranuclear Inheritance,Inheritance, Cytoplasmic,Inheritance, Extrachromosomal,Inheritance, Extranuclear
D012441	Saccharomyces cerevisiae	A species of the genus SACCHAROMYCES, family Saccharomycetaceae, order Saccharomycetales, known as "baker's" or "brewer's" yeast. The dried form is used as a dietary supplement.	Baker's Yeast,Brewer's Yeast,Candida robusta,S. cerevisiae,Saccharomyces capensis,Saccharomyces italicus,Saccharomyces oviformis,Saccharomyces uvarum var. melibiosus,Yeast, Baker's,Yeast, Brewer's,Baker Yeast,S cerevisiae,Baker's Yeasts,Yeast, Baker
D014170	Transformation, Genetic	Change brought about to an organisms genetic composition by unidirectional transfer (TRANSFECTION; TRANSDUCTION, GENETIC; CONJUGATION, GENETIC, etc.) and incorporation of foreign DNA into prokaryotic or eukaryotic cells by recombination of part or all of that DNA into the cell's genome.	Genetic Transformation,Genetic Transformations,Transformations, Genetic