scholarly journals Position effects in ectopic and allelic mitotic recombination in Saccharomyces cerevisiae.

Genetics ◽  
1989 ◽  
Vol 123 (2) ◽  
pp. 261-268 ◽  
Author(s):  
M Lichten ◽  
J E Haber
Keyword(s):  
Meiotic Recombination ◽  
Chromosomal Location ◽  
Mitotic Recombination ◽  
Yeast Genome ◽  
Intragenic Recombination ◽  
Position Effects ◽  
Ectopic Recombination ◽  
Leu2 Gene ◽  
Genomic Location ◽  
Strong Position

Abstract We have examined the role that genomic location plays in mitotic intragenic recombination. Mutant alleles of the LEU2 gene were inserted at five locations in the yeast genome. Diploid and haploid strains containing various combinations of these inserts were used to examine both allelic recombination (between sequences at the same position on parental homologs) and ectopic recombination (between sequences at nonallelic locations). Chromosomal location had little effect on mitotic allelic recombination. The rate of recombination to LEU2 at five different loci varied less than threefold. This finding contrasts with previous observations of strong position effects in meiosis; frequencies of meiotic recombination at the same five loci differ by about a factor of forty. Mitotic recombination between dispersed copies of leu2 displayed strong position effects. Copies of leu2 located approximately 20 kb apart on the same chromosome recombined at rates 6-13-fold higher than those observed for allelic copies of leu2. leu2 sequences located on nonhomologous chromosomes or at distant loci on the same chromosome recombined at rates similar to those observed for allelic copies. We suggest that, during mitosis, parental homologs interact with each other no more frequently than do nonhomologous chromosomes.

scholarly journals Allelic and ectopic recombination between Ty elements in yeast.

Genetics ◽  
1988 ◽  
Vol 119 (3) ◽  
pp. 549-559
Author(s):  
M Kupiec ◽  
T D Petes
Keyword(s):  
Meiotic Recombination ◽  
Mitotic Recombination ◽  
Common Occurrence ◽  
Ectopic Recombination ◽  
Ty Elements ◽  
Different Types ◽  
The Common ◽  
Isogenic Strains

Abstract Allelic and nonallelic (ectopic) recombination events were analyzed in a set of isogenic strains that carry marked Ty elements. We found that allelic recombination between Ty elements occurred at normal frequencies both in meiosis and mitosis. The marked Ty elements were involved in a large variety of different types of ectopic recombination and this variety was greater in mitosis than in meiosis. Allelic and ectopic recombination events occurred at similar frequencies in mitosis, but allelic recombination predominated in meiosis. Some of the types of ectopic mitotic recombination indicated the common occurrence of concerted recombination events. The length of homology represented by a delta element (330 bp) seemed to be sufficient for some types of mitotic and meiotic recombination.

scholarly journals EFFECTS OF THE RAD52 GENE ON RECOMBINATION IN SACCHAROMYCES CEREVISIAE

Genetics ◽  
1980 ◽  
Vol 94 (1) ◽  
pp. 31-50
Author(s):  
Satya Prakash ◽  
Louise Prakash ◽  
William Burke ◽  
Beth A Montelone
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Gene Function ◽  
Meiotic Recombination ◽  
Mitotic Recombination ◽  
Intragenic Recombination ◽  
Sporulation Medium ◽  
Time Intervals ◽  
Spontaneous Reversion ◽  
Γ Ray ◽  
Intergenic Recombination

ABSTRACT Effects of the rad52 mutation in Saccharomyces cerevisiae on meiotic, γ-ray-induced, UV-induced and spontaneous mitotic recombination were studied. The rad52/rad52 diploids undergo premeiotic DNAsynthesis; sporulation occurs hut inviable spores are produced. Both intra and intergenic recombination during meiosis were examined in cells transferred from sporulation medium to vegetative medium at different time intervals. No intragenic recombination was observed at the hisl-ljhis1-315 and trp5-2/trp5-48 hetero-alleles. Gene-centromere recombination also was not observed in rad52/rad52 diploids. No γ-ray- or UV-induced intragenic mitotic recombination is seen in rad52/rad52 diploids. The rate of spontaneous mitotic recombination is lowered five-fold at the hisf -1/hisf-315 and leu1-c/leu1-12 heteroalleles. Spontaneous reversion rates of both hisf-1 and hisf-315 were elevated 10to 20 fold in rad52/rad52 diploids.—The RAD52 gene function is required for spontaneous mitotic recombination, UV- and γ-ray-induced mitotic recombination and meiotic recombination.

Substrate length requirements for efficient mitotic recombination in Saccharomyces cerevisiae

1993 ◽  
Vol 13 (7) ◽  
pp. 3937-3950
Author(s):  
S Jinks-Robertson ◽  
M Michelitch ◽  
S Ramcharan
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Gene Conversion ◽  
Mitotic Recombination ◽  
Yeast Genome ◽  
Inverted Repeats ◽  
Ectopic Recombination ◽  
Linear Relationships ◽  
Recombination System ◽  
Efficient Processing ◽  
Substrate Size

An ectopic recombination system using ura3 heteroalleles varying in size from 80 to 960 bp has been used to examine the effect of substrate length on spontaneous mitotic recombination. The ura3 heteroalleles were positioned either on nonhomologous chromosomes (heterochromosomal repeats) or as direct or inverted repeats on the same chromosome (intrachromosomal repeats). While the intrachromosomal events occur at rates at least 2 orders of magnitude greater than the corresponding heterochromosomal events, the recombination rate for each type of repeat considered separately exhibits a linear dependence on substrate length. The linear relationships allow estimation of the corresponding minimal efficient processing segments, which are approximately 250 bp regardless of the relative positions of the repeats in the yeast genome. An examination of the distribution of recombination events into simple gene conversion versus crossover events indicates that reciprocal exchange is more sensitive to substrate size than is gene conversion.

scholarly journals The Saccharomyces cerevisiae RDN1 Locus Is Sequestered From Interchromosomal Meiotic Ectopic Recombination in a SIR2-Dependent Manner

Genetics ◽  
2000 ◽  
Vol 155 (3) ◽  
pp. 1019-1032
Author(s):  
Edward S Davis ◽  
Brenda K Shafer ◽  
Jeffrey N Strathern
Keyword(s):  
Gene Expression ◽  
Meiotic Recombination ◽  
Rdna Locus ◽  
Yeast Genome ◽  
Dependent Manner ◽  
Ectopic Recombination ◽  
The Poor ◽  
Homology Searching ◽  
Low Rate ◽  
Recombination Gene

Abstract Meiotic ectopic recombination occurs at similar frequencies among many sites in the yeast genome, suggesting that all loci are similarly accessible to homology searching. In contrast, we found that his3 sequences integrated in the RDN1 (rDNA) locus were unusually poor participants in meiotic recombination with his3 sequences at other sites. We show that the low rate of meiotic ectopic recombination resulted from the poor ability of RDN1::his3 to act as a donor sequence. SIR2 partially repressed interchromosomal meiotic ectopic recombination at RDN1, consistent with its role in regulating recombination, gene expression, and retrotransposition within RDN1. We propose that RDN1 is physically sequestered from meiotic homology searching mechanisms.

scholarly journals Substrate length requirements for efficient mitotic recombination in Saccharomyces cerevisiae.

1993 ◽  
Vol 13 (7) ◽  
pp. 3937-3950 ◽  
Author(s):  
S Jinks-Robertson ◽  
M Michelitch ◽  
S Ramcharan
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Gene Conversion ◽  
Mitotic Recombination ◽  
Yeast Genome ◽  
Inverted Repeats ◽  
Ectopic Recombination ◽  
Linear Relationships ◽  
Recombination System ◽  
Efficient Processing ◽  
Substrate Size

An ectopic recombination system using ura3 heteroalleles varying in size from 80 to 960 bp has been used to examine the effect of substrate length on spontaneous mitotic recombination. The ura3 heteroalleles were positioned either on nonhomologous chromosomes (heterochromosomal repeats) or as direct or inverted repeats on the same chromosome (intrachromosomal repeats). While the intrachromosomal events occur at rates at least 2 orders of magnitude greater than the corresponding heterochromosomal events, the recombination rate for each type of repeat considered separately exhibits a linear dependence on substrate length. The linear relationships allow estimation of the corresponding minimal efficient processing segments, which are approximately 250 bp regardless of the relative positions of the repeats in the yeast genome. An examination of the distribution of recombination events into simple gene conversion versus crossover events indicates that reciprocal exchange is more sensitive to substrate size than is gene conversion.

scholarly journals Crossing Over Is Rarely Associated With Mitotic Intragenic Recombination in Schizosaccharomyces pombe

Genetics ◽  
2001 ◽  
Vol 157 (1) ◽  
pp. 63-77 ◽  
Author(s):  
Jeffrey B Virgin ◽  
Jeffrey P Bailey ◽  
Farnaz Hasteh ◽  
James Neville ◽  
Amy Cole ◽  
...  
Keyword(s):  
Schizosaccharomyces Pombe ◽  
Chromosomal Rearrangements ◽  
Mitotic Recombination ◽  
Intragenic Recombination ◽  
Crossing Over ◽  
Recombination Rates ◽  
Alternative Pathways ◽  
Ectopic Recombination ◽  
Specific Factors ◽  
Differential Control

Abstract Chromosomal rearrangements can result from crossing over during ectopic homologous recombination between dispersed repetitive DNA. We have previously shown that meiotic ectopic recombination between artificially dispersed ade6 heteroalleles in the fission yeast Schizosaccharomyces pombe frequently results in chromosomal rearrangements. The same recombination substrates have been studied in mitotic recombination. Ectopic recombination rates in haploids were ∼1-4 × 10-6 recombinants per cell generation, similar to allelic recombination rates in diploids. In contrast, ectopic recombination rates in heterozygous diploids were 2.5-70 times lower than allelic recombination or ectopic recombination in haploids. These results suggest that diploid-specific factors inhibit ectopic recombination. Very few crossovers occurred in ade6 mitotic recombination, either allelic or ectopic. Allelic intragenic recombination was associated with 2% crossing over, and ectopic recombination between multiple different pairing partners showed 1-7% crossing over. These results contrast sharply with the 35-65% crossovers associated with meiotic ade6 recombination and suggest either differential control of resolution of recombination intermediates or alternative pathways of recombination in mitosis and meiosis.

scholarly journals The Efficiency of Meiotic Recombination Between Dispersed Sequences in Saccharomyces cerevisiae Depends Upon Their Chromosomal Location

Genetics ◽  
1996 ◽  
Vol 144 (1) ◽  
pp. 43-55 ◽  
Author(s):  
Alastair S H Goldman ◽  
Michael Lichten
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Meiotic Recombination ◽  
Chromosomal Location ◽  
Physical Distance ◽  
Special Relationship ◽  
Homologous Chromosomes ◽  
Ectopic Recombination ◽  
End To End

Abstract To examine constraints imposed on meiotic recombination by homologue pairing, we measured the frequency of recombination between mutant alleles of the ARG4 gene contained in pBR322-based inserts. Inserts were located at identical loci on homologues (allelic recombination) or at different loci on either homologous or heterologous chromosomes (ectopic recombination). Ectopic recombination between interstitially located inserts on heterologous chromosomes had an efficiency of 6-12% compared to allelic recombination. By contrast, ectopic recombination between interstitial inserts located on homologues had relative efficiencies of 47-99%. These findings suggest that when meiotic ectopic recombination occurs, homologous chromosomes are already colocalized. The efficiency of ectopic recombination between inserts on homologues decreased as the physical distance between insert sites was increased. This result is consistent with the suggestion that during meiotic recombination, homologues are not only close to each other, but also are aligned end to end. Finally, the efficiency of ectopic recombination between inserts near telomeres (within 16 kb) was significantly greater than that observed with inserts >50 kb from the nearest telomere. Thus, at the time of recombination, there may be a special relationship between the ends of chromosomes not shared with interstitial regions.

scholarly journals Active and inactive transplacement of the M26 recombination hotspot in Schizosaccharomyces pombe.

Genetics ◽  
1995 ◽  
Vol 141 (1) ◽  
pp. 33-48
Author(s):  
J B Virgin ◽  
J Metzger ◽  
G R Smith
Keyword(s):  
Schizosaccharomyces Pombe ◽  
Meiotic Recombination ◽  
Plasmid Dna ◽  
Context Effect ◽  
Intragenic Recombination ◽  
Multicopy Plasmid ◽  
Chromosomal Locus ◽  
Sequence Element ◽  
Recombination Hotspot ◽  
Recombination Hotspots

Abstract The ade6-M26 mutation of the fission yeast Schizosaccharomyces pombe creates a meiotic recombination hotspot that elevates ade6 intragenic recombination approximately 10-15-fold. A heptanucleotide sequence including the M26 point mutation is required but not sufficient for hotspot activity. We studied the effects of plasmid and chromosomal context on M26 hotspot activity. The M26 hotspot was inactive on a multicopy plasmid containing M26 embedded within 3.0 or 5.9 kb of ade6 DNA. Random S. pombe genomic fragments totaling approximately 7 Mb did not activate the M26 hotspot on a plasmid. M26 hotspot activity was maintained when 3.0-, 4.4-, and 5.9-kb ade6-M26 DNA fragments, with various amounts of non-S. pombe plasmid DNA, were integrated at the ura4 chromosomal locus, but only in certain configurations relative to the ura4 gene and the cointegrated plasmid DNA. Several integrations created new M26-independent recombination hotspots. In all cases the non-ade6 DNA was located > 1 kb from the M26 site, and in some cases > 2 kb. Because the chromosomal context effect was transmitted over large distances, and did not appear to be mediated by a single discrete DNA sequence element, we infer that the local chromatin structure has a pronounced effect on M26 hotspot activity.

Saccharomyces cerevisiae Checkpoint Genes MEC1, RAD17 and RAD24 Are Required for Normal Meiotic Recombination Partner Choice

Genetics ◽  
1999 ◽  
Vol 153 (2) ◽  
pp. 607-620 ◽  
Author(s):  
Jeremy M Grushcow ◽  
Teresa M Holzen ◽  
Ken J Park ◽  
Ted Weinert ◽  
Michael Lichten ◽  
...  
Keyword(s):  
Meiotic Recombination ◽  
Mitotic Checkpoint ◽  
Partner Choice ◽  
Wild Type ◽  
Spore Viability ◽  
Checkpoint Signaling ◽  
Ectopic Recombination ◽  
Meiotic Progression ◽  
Checkpoint Genes

Abstract Checkpoint gene function prevents meiotic progression when recombination is blocked by mutations in the recA homologue DMC1. Bypass of dmc1 arrest by mutation of the DNA damage checkpoint genes MEC1, RAD17, or RAD24 results in a dramatic loss of spore viability, suggesting that these genes play an important role in monitoring the progression of recombination. We show here that the role of mitotic checkpoint genes in meiosis is not limited to maintaining arrest in abnormal meioses; mec1-1, rad24, and rad17 single mutants have additional meiotic defects. All three mutants display Zip1 polycomplexes in two- to threefold more nuclei than observed in wild-type controls, suggesting that synapsis may be aberrant. Additionally, all three mutants exhibit elevated levels of ectopic recombination in a novel physical assay. rad17 mutants also alter the fraction of recombination events that are accompanied by an exchange of flanking markers. Crossovers are associated with up to 90% of recombination events for one pair of alleles in rad17, as compared with 65% in wild type. Meiotic progression is not required to allow ectopic recombination in rad17 mutants, as it still occurs at elevated levels in ndt80 mutants that arrest in prophase regardless of checkpoint signaling. These observations support the suggestion that MEC1, RAD17, and RAD24, in addition to their proposed monitoring function, act to promote normal meiotic recombination.

scholarly journals Genetic and physical analysis of the M26 recombination hotspot of Schizosaccharomyces pombe.

Genetics ◽  
1988 ◽  
Vol 119 (3) ◽  
pp. 491-497
Author(s):  
A S Ponticelli ◽  
E P Sena ◽  
G R Smith
Keyword(s):  
Schizosaccharomyces Pombe ◽  
Meiotic Recombination ◽  
Base Pair ◽  
Initiation Site ◽  
Mitotic Recombination ◽  
Physical Analysis ◽  
Nucleotide Change ◽  
Recombination Hotspot ◽  
Base Pair Mismatch

Abstract The ade6-M26 mutation of Schizosaccharomyces pombe has previously been reported to stimulate ade6 intragenic meiotic recombination. We report here that the ade6-M26 mutation is a single G----T nucleotide change, that M26 stimulated recombination within ade6 but not at other distinct loci, and that M26 stimulated meiotic but not mitotic recombination. In addition, M26 stimulated recombination within ade6 when M26 is homozygous; this result demonstrates that a base-pair mismatch at the M26 site was not required for the stimulation. These results are consistent with the ade6-M26 mutation creating a meiotic recombination initiation site.

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