scholarly journals Mitochondrial genetics, circular DNA and the mechanism of thepetitemutation in yeast

1974 ◽  
Vol 24 (1) ◽  
pp. 43-57 ◽  
Author(s):  
G. D. Clark-Walker ◽  
George L. Gabor Miklos
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Structural Rearrangements ◽  
Dna Molecules ◽  
Mitochondrial Genetics ◽  
General Hypothesis ◽  
Mitochondrial Recombination ◽  
Circular Dna ◽  
Bacterial Plasmids ◽  
Circular Dnas

SUMMARYWe propose a general hypothesis involving properties of circular DNA which can explain such phenomena as thepetitemutation, suppressiveness, and the polarity observed in mitochondrial recombination in the yeastSaccharomyces cerevisiae. This hypothesis involves excision and insertion events between circular DNA molecules as well as structural rearrangements in the DNA generated by these events. The special properties of circular DNA have been considered in analysing recombination, and a number of results are obtained which are not intuitively apparent.This hypothesis can be applied to any situation involving circular DNA such as bacterial plasmids and cytoplasmic circular DNAs, where the opportunity exists for recombination and rearrangement events.

Identification of short tandemly repeated sequences in extrachromosomal circular DNAs from Drosophila melanogaster embryos

Genome ◽  
1993 ◽  
Vol 36 (2) ◽  
pp. 244-254 ◽  
Author(s):  
S. Renault ◽  
F. Degroote ◽  
G. Picard
Keyword(s):  
Drosophila Melanogaster ◽  
Satellite Dna ◽  
Intergenic Spacer ◽  
Repeated Sequences ◽  
Basic Unit ◽  
Dna Molecules ◽  
Satellite Dnas ◽  
Circular Dna ◽  
Chi Sequence ◽  
Circular Dnas

A sequence (scl) belonging to the recently identified dodeca satellite family was found to be a major family of extrachromosomal circular DNA molecules from Drosophila melanogaster embryos. The basic unit consists of the 11-bp repeat 5′ ACTGGTCCCGT 3′, is 63% G + C rich, and shares some similarity with the Escherichia coli chi sequence. This family accounts for only about 0.06% of the genome but very likely for a higher proportion of the circular DNA molecules. It is organized in the genome into at least five main clusters contained in DNA fragments larger than 20 kb and several minor clusters. These clusters are located in the heterochromatic pericentromeric regions. Two other families of simple repeated sequences, the 1.686 g/cm3 (5′ AATAACATAG 3′) and the 1.705 g/cm3 (5′ AAGAG 3′) satellite DNAs, were also found in circular DNAs, while another family, the 1.672 g/cm3 (5′ AATAT 3′), was not detected. The representation of the simple repeated sequences in circular molecules is not correlated to their genomic representation. Among the seven families of sequences identified to date in extrachromosomal circular DNAs from embryos, the dodeca satellite, the 240-bp repeat of the rDNA intergenic spacer, and the 1.688 and 1.705 g/cm3 satellite DNAs are the most represented families, while the 5S genes, the histone genes, and the 1.686 g/cm3 satellite DNA are present in a lower amount.Key words: D. melanogaster, extrachromosomal circular DNAs, repeated sequences, satellite DNA.

scholarly journals Replicative aging is associated with loss of genetic heterogeneity from extrachromosomal circular DNA in Saccharomyces cerevisiae

2020 ◽  
Vol 48 (14) ◽  
pp. 7883-7898 ◽  
Author(s):  
Iñigo Prada-Luengo ◽  
Henrik D Møller ◽  
Rasmus A Henriksen ◽  
Qian Gao ◽  
Camilla Eggert Larsen ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Genetic Variation ◽  
Ribosomal Dna ◽  
Replicative Aging ◽  
Circular Dna ◽  
Circular Dnas ◽  
Low Glucose ◽  
Chromosomal Amplifications ◽  
Mother Cells ◽  
Massive Accumulation

Abstract Circular DNA can arise from all parts of eukaryotic chromosomes. In yeast, circular ribosomal DNA (rDNA) accumulates dramatically as cells age, however little is known about the accumulation of other chromosome-derived circles or the contribution of such circles to genetic variation in aged cells. We profiled circular DNA in Saccharomyces cerevisiae populations sampled when young and after extensive aging. Young cells possessed highly diverse circular DNA populations but 94% of the circular DNA were lost after ∼15 divisions, whereas rDNA circles underwent massive accumulation to >95% of circular DNA. Circles present in both young and old cells were characterized by replication origins including circles from unique regions of the genome and repetitive regions: rDNA and telomeric Y’ regions. We further observed that circles can have flexible inheritance patterns: [HXT6/7circle] normally segregates to mother cells but in low glucose is present in up to 50% of cells, the majority of which must have inherited this circle from their mother. Interestingly, [HXT6/7circle] cells are eventually replaced by cells carrying stable chromosomal HXT6 HXT6/7 HXT7 amplifications, suggesting circular DNAs are intermediates in chromosomal amplifications. In conclusion, the heterogeneity of circular DNA offers flexibility in adaptation, but this heterogeneity is remarkably diminished with age.

scholarly journals The adaptive potential of circular DNA accumulation in ageing cells

2020 ◽  
Vol 66 (5) ◽  
pp. 889-894 ◽  
Author(s):  
Ryan M. Hull ◽  
Jonathan Houseley
Keyword(s):  
Genetic Material ◽  
Normal Growth ◽  
Mendelian Inheritance ◽  
Dna Molecules ◽  
Chromosomal Dna ◽  
Protein Coding ◽  
Circular Dna ◽  
Recombination Processes ◽  
Circular Dnas

Abstract Carefully maintained and precisely inherited chromosomal DNA provides long-term genetic stability, but eukaryotic cells facing environmental challenges can benefit from the accumulation of less stable DNA species. Circular DNA molecules lacking centromeres segregate randomly or asymmetrically during cell division, following non-Mendelian inheritance patterns that result in high copy number instability and massive heterogeneity across populations. Such circular DNA species, variously known as extrachromosomal circular DNA (eccDNA), microDNA, double minutes or extrachromosomal DNA (ecDNA), are becoming recognised as a major source of the genetic variation exploited by cancer cells and pathogenic eukaryotes to acquire drug resistance. In budding yeast, circular DNA molecules derived from the ribosomal DNA (ERCs) have been long known to accumulate with age, but it is now clear that aged yeast also accumulate other high-copy protein-coding circular DNAs acquired through both random and environmentally-stimulated recombination processes. Here, we argue that accumulation of circular DNA provides a reservoir of heterogeneous genetic material that can allow rapid adaptation of aged cells to environmental insults, but avoids the negative fitness impacts on normal growth of unsolicited gene amplification in the young population.

Characterization of circular DNA molecules from cotton plants with leaf curl disease

2018 ◽  
Vol 51 (1) ◽  
Author(s):  
Sohail Akhtar ◽  
Muhammad Nouman Tahir ◽  
Imran Amin ◽  
Rana Binyamin ◽  
Shahid Mansoor
Keyword(s):  
Dna Molecules ◽  
Circular Dna ◽  
Cotton Plants ◽  
Leaf Curl Disease ◽  
Leaf Curl

Catenated Circular DNA Molecules in HeLa Cell Mitochondria

Nature ◽  
1967 ◽  
Vol 216 (5116) ◽  
pp. 647-652 ◽  
Author(s):  
BRUCE HUDSON ◽  
JEROME VINOGRAD
Keyword(s):  
Hela Cell ◽  
Dna Molecules ◽  
Circular Dna

scholarly journals Amplicon structure in multidrug-resistant murine cells: a nonrearranged region of genomic DNA corresponding to large circular DNA.

1992 ◽  
Vol 12 (3) ◽  
pp. 1179-1187 ◽  
Author(s):  
F Ståhl ◽  
Y Wettergren ◽  
G Levan
Keyword(s):  
Tumor Cell ◽  
Cell Line ◽  
Single Unit ◽  
Parental Cell ◽  
Parental Cell Line ◽  
Mouse Tumor ◽  
Dna Molecules ◽  
Circular Dna ◽  
Double Minutes ◽  
Mdr Genes

Multidrug resistance (MDR) in tumor cell lines is frequently correlated with amplification of one or more mdr genes. Usually the amplified domain also includes several neighboring genes. Using pulsed-field gel electrophoresis, we have established a restriction map covering approximately 2,200 kb in the drug-sensitive mouse tumor cell line TC13K. The mapped region is located on mouse chromosome 5 and includes the three mdr genes, the gene for the calcium-binding sorcin protein, and a gene with unknown function designated class 5. Long-range maps of the amplified DNA sequences in five of six MDR sublines that had been independently derived from TC13K generally displayed the same pattern as did the parental cell line. All six MDR sublines exhibited numerous double minutes, and one of them displayed a homogeneously staining region in a subpopulation. Large circular molecules, most likely identical to one chromatid of the double minutes, were detected in four of the sublines by linearization with gamma irradiation. The size of the circles was about 2,500 kb, which correlated to a single unit of the amplified domain. We therefore propose that in four independent instances of MDR development, a single unit of about 2,500 kb has been amplified in the form of circular DNA molecules. The restriction enzyme map of the amplified unit is unchanged compared with that of the parental cell line, whereas the joining sites of the circular DNA molecules are not identical but are in the same region.

scholarly journals Visualization of circular DNA molecules labeled with colloidal gold spheres using atomic force microscopy

1993 ◽  
Vol 11 (4) ◽  
pp. 820-823 ◽  
Author(s):  
Wen‐Ling Shaiu ◽  
James Vesenka ◽  
Daniel Jondle ◽  
Eric Henderson ◽  
Drena D. Larson
Keyword(s):  
Atomic Force Microscopy ◽  
Colloidal Gold ◽  
Dna Molecules ◽  
Circular Dna ◽  
Force Microscopy ◽  
Atomic Force
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