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Distinct functions of S. pombe Rec12 (Spo11) protein and Rec12-dependent crossover recombination (chiasmata) in meiosis I; and a requirement for Rec12 in meiosis II.

Sharif WD, Glick GG, Davidson MK, Wahls WP - Cell Chromosome (2002)

Bottom Line: CONCLUSIONS: Rec12 is a 345 amino acid protein required for most crossover recombination and for chiasmatic segregation of chromosomes during meiosis I.Rec12 also participates in a backup distributive (achiasmatic) system of chromosome segregation during meiosis I.In addition, catalytically-active Rec12 mediates some signal that is required for faithful equational segregation of chromosomes during meiosis II.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Biochemistry and Molecular Biology, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA. WahlsWayneP@uams.edu

ABSTRACT
BACKGROUND: In most organisms proper reductional chromosome segregation during meiosis I is strongly correlated with the presence of crossover recombination structures (chiasmata); recombination deficient mutants lack crossovers and suffer meiosis I nondisjunction. We report that these functions are separable in the fission yeast Schizosaccharomyces pombe. RESULTS: Intron mapping and expression studies confirmed that Rec12 is a member of the Spo11/Top6A topoisomerase family required for the formation of meiotic dsDNA breaks and recombination. rec12-117, rec12-D15 (), and rec12-Y98F (active site) mutants lacked most crossover recombination and chromosomes segregated abnormally to generate aneuploid meiotic products. Since S. pombe contains only three chromosome pairs, many of those aneuploid products were viable. The types of aberrant chromosome segregation were inferred from the inheritance patterns of centromere linked markers in diploid meiotic products. The rec12-117 and rec12-D15 mutants manifest segregation errors during both meiosis I and meiosis II. Remarkably, the rec12-Y98F (active site) mutant exhibited essentially normal meiosis I segregation patterns, but still exhibited meiosis II segregation errors. CONCLUSIONS: Rec12 is a 345 amino acid protein required for most crossover recombination and for chiasmatic segregation of chromosomes during meiosis I. Rec12 also participates in a backup distributive (achiasmatic) system of chromosome segregation during meiosis I. In addition, catalytically-active Rec12 mediates some signal that is required for faithful equational segregation of chromosomes during meiosis II.

No MeSH data available.


Related in: MedlinePlus

Formation of aneuploid meiotic products. (A) Spore viabilities. (B) Frequencies of diploid meiotic products. Data are the mean ± standard deviation from six separate experiments involving crosses of strains WSP0602 × WSP0603; WSP0079 × WSP1799; WSP1813 × WSP1819; and WSP1556 × WSP1559.
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Figure 4: Formation of aneuploid meiotic products. (A) Spore viabilities. (B) Frequencies of diploid meiotic products. Data are the mean ± standard deviation from six separate experiments involving crosses of strains WSP0602 × WSP0603; WSP0079 × WSP1799; WSP1813 × WSP1819; and WSP1556 × WSP1559.

Mentions: Approximately 50% of the meiotic products from the rec12-117 and rec12-D15 () mutants were inviable (Figure 4A), indicating that about 50% of the products were isomic for one or more chromosomes. This value is close to the frequency (58%) of isomics that one would expect if chromosome segregation were completely random in either one of the two meiotic divisions. Interestingly, the rec12-Y98F mutant produced a significantly higher frequency of inviable spores than the rec12-117 and rec12-D15 mutants (Figure 4A), suggesting that rec12-Y98F is a separation of function mutation.


Distinct functions of S. pombe Rec12 (Spo11) protein and Rec12-dependent crossover recombination (chiasmata) in meiosis I; and a requirement for Rec12 in meiosis II.

Sharif WD, Glick GG, Davidson MK, Wahls WP - Cell Chromosome (2002)

Formation of aneuploid meiotic products. (A) Spore viabilities. (B) Frequencies of diploid meiotic products. Data are the mean ± standard deviation from six separate experiments involving crosses of strains WSP0602 × WSP0603; WSP0079 × WSP1799; WSP1813 × WSP1819; and WSP1556 × WSP1559.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC131009&req=5

Figure 4: Formation of aneuploid meiotic products. (A) Spore viabilities. (B) Frequencies of diploid meiotic products. Data are the mean ± standard deviation from six separate experiments involving crosses of strains WSP0602 × WSP0603; WSP0079 × WSP1799; WSP1813 × WSP1819; and WSP1556 × WSP1559.
Mentions: Approximately 50% of the meiotic products from the rec12-117 and rec12-D15 () mutants were inviable (Figure 4A), indicating that about 50% of the products were isomic for one or more chromosomes. This value is close to the frequency (58%) of isomics that one would expect if chromosome segregation were completely random in either one of the two meiotic divisions. Interestingly, the rec12-Y98F mutant produced a significantly higher frequency of inviable spores than the rec12-117 and rec12-D15 mutants (Figure 4A), suggesting that rec12-Y98F is a separation of function mutation.

Bottom Line: CONCLUSIONS: Rec12 is a 345 amino acid protein required for most crossover recombination and for chiasmatic segregation of chromosomes during meiosis I.Rec12 also participates in a backup distributive (achiasmatic) system of chromosome segregation during meiosis I.In addition, catalytically-active Rec12 mediates some signal that is required for faithful equational segregation of chromosomes during meiosis II.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Biochemistry and Molecular Biology, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA. WahlsWayneP@uams.edu

ABSTRACT
BACKGROUND: In most organisms proper reductional chromosome segregation during meiosis I is strongly correlated with the presence of crossover recombination structures (chiasmata); recombination deficient mutants lack crossovers and suffer meiosis I nondisjunction. We report that these functions are separable in the fission yeast Schizosaccharomyces pombe. RESULTS: Intron mapping and expression studies confirmed that Rec12 is a member of the Spo11/Top6A topoisomerase family required for the formation of meiotic dsDNA breaks and recombination. rec12-117, rec12-D15 (), and rec12-Y98F (active site) mutants lacked most crossover recombination and chromosomes segregated abnormally to generate aneuploid meiotic products. Since S. pombe contains only three chromosome pairs, many of those aneuploid products were viable. The types of aberrant chromosome segregation were inferred from the inheritance patterns of centromere linked markers in diploid meiotic products. The rec12-117 and rec12-D15 mutants manifest segregation errors during both meiosis I and meiosis II. Remarkably, the rec12-Y98F (active site) mutant exhibited essentially normal meiosis I segregation patterns, but still exhibited meiosis II segregation errors. CONCLUSIONS: Rec12 is a 345 amino acid protein required for most crossover recombination and for chiasmatic segregation of chromosomes during meiosis I. Rec12 also participates in a backup distributive (achiasmatic) system of chromosome segregation during meiosis I. In addition, catalytically-active Rec12 mediates some signal that is required for faithful equational segregation of chromosomes during meiosis II.

No MeSH data available.


Related in: MedlinePlus