Nonrandom transition from asymmetrical to symmetrical hybrid DNA during meiotic recombination

Genome ◽  
1989 ◽  
Vol 32 (3) ◽  
pp. 414-419 ◽  
Author(s):  
Angelos Kalogeropoulos ◽  
Jean-Luc Rossignol
Keyword(s):  
Meiotic Recombination ◽  
Heteroduplex Dna ◽  
Dna Distribution ◽  
Left Part ◽  
Ascobolus Immersus ◽  
Two Phases ◽  
The Right ◽  
Hybrid Dna

During meiotic recombination, in the b2 gene of Ascobolus immersus hybrid DNA can be formed either on only one (asymmetrical hybrid DNA) or on both (symmetrical hybrid DNA) interacting chromatids. The two phases can be found in the same meiosis, involving the same two interacting chromatids with the symmetrical phase located on the right with regard to the asymmetrical one. We show that the transition from the asymmetrical to the symmetrical phase occurs in a defined region located within the left part of the gene, which is closer to the initiation region. Once formed, the symmetrical hybrid DNA phase seems always to extend to the rightmost mutation sites. This contrasts with asymmetrical hybrid DNA extension, which when it stays in asymmetrical form, may stop within the gene.Key words: Ascobolus immersus, heteroduplex DNA distribution.

scholarly journals Meiotic mismatch repair quantified on the basis of segregation patterns in Schizosaccharomyces pombe.

Genetics ◽  
1993 ◽  
Vol 133 (4) ◽  
pp. 815-824 ◽  
Author(s):  
P Schär ◽  
P Munz ◽  
J Kohli
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Schizosaccharomyces Pombe ◽  
Detailed Analysis ◽  
Mismatch Repair ◽  
Meiotic Recombination ◽  
Wild Type ◽  
Base Pairs ◽  
Ascobolus Immersus ◽  
Postmeiotic Segregation ◽  
Hybrid Dna

Abstract Hybrid DNA with mismatched base pairs is a central intermediate of meiotic recombination. Mismatch repair leads either to restoration or conversion, while failure of repair results in postmeiotic segregation (PMS). The behavior of three G to C transversions in one-factor crosses with the wild-type alleles is studied in Schizosaccharomyces pombe. They lead to C/C and G/G mismatches and are compared with closely linked mutations yielding other mismatches. A method is presented for the detection of PMS in random spores. The procedure yields accurate PMS frequencies as shown by comparison with tetrad data. A scheme is presented for the calculation of the frequency of hybrid DNA formation and the efficiency of mismatch repair. The efficiency of C/C repair in S. pombe is calculated to be about 70%. Other mismatches are repaired with close to 100% efficiency. These results are compared with data published on mutations in Saccharomyces cerevisiae and Ascobolus immersus. This study forms the basis for the detailed analysis of the marker effects caused by G to C transversions in two-factor crosses.

scholarly journals Poorly Repaired Mismatches in Heteroduplex DNA are Hyper-Recombinagenic in Saccharomyces cerevisiae

Genetics ◽  
1996 ◽  
Vol 142 (2) ◽  
pp. 407-416 ◽  
Author(s):  
P Manivasakam ◽  
Susan M Rosenberg ◽  
P J Hastings
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Mismatch Repair ◽  
Genetic Markers ◽  
Meiotic Recombination ◽  
Repair System ◽  
Normal Allele ◽  
Heteroduplex Dna ◽  
Mismatch Repair System ◽  
Postmeiotic Segregation ◽  
System Operating

Abstract In yeast meiotic recombination, alleles used as genetic markers fall into two classes as regards their fate when incorporated into heteroduplex DNA. Normal alleles are those that form heteroduplexes that are nearly always recognized and corrected by the mismatch repair system operating in meiosis. High PMS (postmeiotic segregation) alleles form heteroduplexes that are inefficiently mismatch repaired. We report that placing any of several high PMS alleles very close to normal alleles causes hyperrecombination between these markers. We propose that this hyperrecombination is caused by the high PMS allele blocking a mismatch repair tract initiated from the normal allele, thus preventing corepair of the two alleles, which would prevent formation of recombinants. The results of three point crosses involving two PMS alleles and a normal allele suggest that high PMS alleles placed between two alleles that are normally corepaired block that corepair.

scholarly journals Recombination within the Y locus in Ascobolus immersus

1967 ◽  
Vol 9 (2) ◽  
pp. 159-177 ◽  
Author(s):  
A. Kruszewska ◽  
W. Gajewski
Keyword(s):  
Opposite Direction ◽  
Negative Correlation ◽  
Linear Order ◽  
Great Majority ◽  
Wild Type Allele ◽  
Wild Type ◽  
Marker Effect ◽  
Dna Models ◽  
Ascobolus Immersus ◽  
Hybrid Dna

Mutants of the Y locus differed appreciably in their basic conversion frequencies (frequencies of conversion in one-point crosses) to wild type. The differences in the basic conversion frequencies in the opposite direction, i.e. from corresponding wild-type allele to mutant, were in general not pronounced. For some alleles frequencies of conversion in both directions were similar, but for the others they differed markedly. No evident correlation between the position of mutants on the map and their basic conversion frequencies was observed.In two-point crosses in repulsion, the great majority of recombinant octads were of conversion type. In these crosses symmetry or asymmetry of conversion depended mainly on similarity or differences in basic conversion frequencies of mutants crossed. In crosses between mutants from different clusters the recombination frequencies were near to the sums of their basic conversion frequencies. Such ‘mutant specificity’ makes it impossible to establish the linear order of mutants on the basis of recombination frequencies in two-point crosses.The results of two-point crosses in repulsion between mutants within clusters pointed to the influence of one allele on the frequency of conversion of another one. This ‘marker effect’ was also evident in some three-point crosses.The frequencies of simultaneous conversions in two-point crosses in coupling did not show negative correlation with the distances between the mutants involved.It seems that many of the data presented here are most easily explained by recently developed hybrid DNA models.

A Test of the Double-Strand Break Repair Model for Meiotic Recombination in Saccharomyces cerevisiae

Genetics ◽  
1996 ◽  
Vol 144 (1) ◽  
pp. 27-41 ◽  
Author(s):  
Larry A Gilbertson ◽  
Franklin W Stahl
Keyword(s):  
Meiotic Recombination ◽  
Strand Break ◽  
Double Strand Break ◽  
Double Strand Break Repair ◽  
Holliday Junction ◽  
Single Event ◽  
Heteroduplex Dna ◽  
Holliday Junction Resolvase ◽  
Break Repair ◽  
Two Sides

Abstract We tested predictions of the double-strand break repair (DSBR) model for meiotic recombination by examining the segregation patterns of small palindromic insertions, which frequently escape mismatch repair when in heteroduplex DNA. The palindromes flanked a well characterized DSB site at the ARC4 locus. The “canonical” DSBR model, in which only 5′ ends are degraded and resolution of the four-stranded intermediate is by Holliday junction resolvase, predicts that hDNA will frequently occur on both participating chromatids in a single event. Tetrads reflecting this configuration of hDNA were rare. In addition, a class of tetrads not predicted by the canonical DSBR model was identified. This class represented events that produced hDNA in a “trans” configuration, on opposite strands of the same duplex on the two sides of the DSB site. Whereas most classes of convertant tetrads had typical frequencies of associated crossovers, tetrads with trans hDNA were parental for flanking markers. Modified versions of the DSBR model, including one that uses a topoisomerase to resolve the canonical DSBR intermediate, are supported by these data.

scholarly journals Reciprocal exchanges instigated by large heterologies in the b2 gene of ascobolus are not associated with long adjacent hybrid DNA stretches.

Genetics ◽  
1988 ◽  
Vol 119 (2) ◽  
pp. 329-336
Author(s):  
T Langin ◽  
H Hamza ◽  
V Haedens ◽  
J L Rossignol
Keyword(s):  
Gene Conversion ◽  
Dna Sequence ◽  
Sequence Homology ◽  
Holliday Junctions ◽  
Holliday Junction ◽  
Mendelian Segregation ◽  
Ascobolus Immersus ◽  
Postmeiotic Segregation ◽  
Single Branch ◽  
Hybrid Dna

Abstract In the gene b2 of Ascobolus immersus, large heterologies increase the frequencies of reciprocal exchanges on their upstream border (corresponding to the high non-Mendelian segregation side). Tests were made to determine whether these reciprocal exchanges, instigated by large heterologies, resulted from the blockage of a Holliday junction bordering a hybrid DNA tract extending from the end of the gene to the heterology. Three types of experiments were performed to answer this question. In all cases, results did not correlate the presence of reciprocal exchanges instigated by large heterologies with the presence of adjacent hybrid DNA tracts. These reciprocal exchanges were rarely associated with postmeiotic segregation at upstream markers, they were not associated with gene conversion of a marker within the interval and their frequency was not decreased by decreasing the frequency of hybrid DNA formation in the gene. These results led to the proposal of the existence of a precursor to reciprocal exchange different from a single branch-migrating Holliday junction. This precursor migrates rightward and its migration is dependent on the DNA sequence homology. The existence of this precursor does not exclude that reciprocal exchanges resulting from the maturation of single Holliday junctions bordering adjacent hybrid DNA tracts could also occur.

Oxygen delivery rate and sufficiency of oxygenation during ECMO in newborn baboons

1989 ◽  
Vol 66 (1) ◽  
pp. 210-216
Author(s):  
J. D. Cornish ◽  
D. R. Gerstmann ◽  
D. M. Null ◽  
M. D. Smith ◽  
T. J. Kuehl
Keyword(s):  
Phase 1 ◽  
Ductus Arteriosus ◽  
Serum Lactate ◽  
Papio Cynocephalus ◽  
Phase 2 ◽  
Primate Model ◽  
O2 Extraction ◽  
Two Phases ◽  
The Right ◽  
O2 Delivery

Minimum acceptable O2 delivery (DO2) during extracorporeal membrane oxygenation (ECMO) remains to be defined in a newborn primate model. The right atrium, carotid artery, and femoral artery were cannulated, and the ductus arteriosus, aorta, and pulmonary artery ligated in neonatal baboons (Papio cynocephalus) under a combination of ketamine, diazepam, and pancuronium. The internal jugular vein was also cannulated retrograde to the level of the occipital ridge. We measured hemoglobin, pH, arterial and venous PO2 (both from the pump circuit and from the cerebral venous site), serum lactate and bicarbonate concentrations, and pump flow, and we calculated hemoglobin saturations, (DO2), O2 consumption (VO2), systemic O2 extraction, and cerebral O2 extraction. Six baboons were studied during each of two phases of the experiment. In the first, flow rates were varied sequentially from 200 to 50 ml.kg-1.min-1 with saturation maximized. In the second, flow was maintained at 200 ml.kg-1.min-1 and saturation was reduced sequentially from 100 to 38%. VO2 fell significantly below baseline at a flow rate of 50 ml.kg-1.min-1 and a DO2 of 8 +/- 2 (SE) ml.kg-1.min-1 in phase 1 and at DO2 of 12 +/- 5 in phase 2. Both systemic and cerebral O2 extraction rose significantly at a flow of 100 ml.kg-1.min-1 and DO2 of 17 +/- 4 ml.kg-1.min-1 in phase 1, whereas neither rose with decreasing DO2 in phase 2. In fact, cerebral extraction fell significantly DO2 of 16 +/- 6 ml.kg-1.min-1.(ABSTRACT TRUNCATED AT 250 WORDS)

Relationship between asymmetrical and symmetrical hybrid DNA formation during meiotic recombination

1980 ◽  
Vol 1 (3) ◽  
pp. 185-191 ◽  
Author(s):  
J. -L. Rossignol ◽  
V. Haedens
Keyword(s):  
Meiotic Recombination ◽  
Hybrid Dna

scholarly journals Right of Knowing and Using Mother Tongue: A Mixed Method Study

2017 ◽  
Vol 10 (12) ◽  
pp. 15
Author(s):  
Burhan Ozfidan
Keyword(s):  
Data Collection ◽  
Mixed Method ◽  
School Attendance ◽  
Mother Tongue ◽  
Thinking Skills ◽  
Language Curriculum ◽  
Mother Tongue Education ◽  
Self Confidence ◽  
Two Phases ◽  
The Right

Language is a crucial factor for the academic achievement of minority people. Speaking the mother tongue in school increases self-confidence and thinking skills, and conveys freedom of speech. Mother tongue is an inseparable element of his or her culture and that everyone has the right to learn his or her mother tongue. The main objective of this current study is to illustrate the need for a language curriculum and to investigate what parameters will influence the development of a mother tongue. This study used an explanatory sequential mixed method, conducted in two phases: a quantitative phase followed by a qualitative phase. For quantitative data collection, 140 participants responded the survey instrument. For qualitative data collection, 12 participants were interviewed. The results indicated that everyone has the right to be taught in their mother tongue. Mother tongue education is necessary for a student to have an equal access to education and gain benefits from education as do others. Mother tongue education has a crucial role in ensuring school attendance, raising the quality of education, and integrating children into society. Therefore, the findings reflected that a bilingual education program is necessary to be educated in mother tongue.

scholarly journals Heteroduplex DNA in Meiotic Recombination in Drosophila mei-9 Mutants

Genetics ◽  
2007 ◽  
Vol 176 (1) ◽  
pp. 63-72 ◽  
Author(s):  
Sarah J. Radford ◽  
Susan McMahan ◽  
Hunter L. Blanton ◽  
Jeff Sekelsky
Keyword(s):  
Meiotic Recombination ◽  
Heteroduplex Dna
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