scholarly journals Characterization of rec7, an Early Meiotic Recombination Gene in Schizosaccharomyces pombe

Genetics ◽  
2001 ◽  
Vol 157 (2) ◽  
pp. 519-532 ◽  
Author(s):  
Monika Molnar ◽  
Sandro Parisi ◽  
Yoshito Kakihara ◽  
Hiroshi Nojima ◽  
Ayumu Yamamoto ◽  
...  
Keyword(s):  
Schizosaccharomyces Pombe ◽  
Meiotic Recombination ◽  
Meiotic Division ◽  
Specific Expression ◽  
Homologous Chromosomes ◽  
Disruption Mutant ◽  
Whole Cells ◽  
Functional Homolog ◽  
Linear Elements ◽  
Meiosis I

Abstract rec7 is involved in intra- and intergenic meiotic recombination in all tested regions of the genome of the fission yeast Schizosaccharomyces pombe. Segregational analysis in a rec7 gene disruption mutant revealed frequent occurrence of two-spored asci. Spores giving rise to diploid colonies were shown to derive from skipping of the second meiotic division. Nondisjunction of homologous chromosomes at the first meiotic division was also frequent. The cytological structures and processes, such as formation of linear elements, pairing of homologous chromosomes, and clustering of telomeres and centromeres, are regular in the mutant. Northern blot experiments revealed meiosis-specific expression of rec7. Screening of a meiotic cDNA library also identified transcripts from the opposite strand in the rec7 region. A Rec7-GFP fusion protein was localized in the nucleus of whole cells before karyogamy, during prophase, and after meiosis I. On spreads of prophase nuclei approximately 50 foci of Rec7-GFP were counted. Some of the observed phenotypes of the disruption mutant and the N-terminal sequence homology suggest that Rec7p is a functional homolog of Rec114p of Saccharomyces cerevisiae. The observed phenotypes of the disruption and the appearance of Rec7-GFP in mating haploid cells and after meiosis I are consistent with Rec7p functions before, during, and after meiotic prophase.

scholarly journals Nonrandom Homolog Segregation at Meiosis I in Schizosaccharomyces pombe Mutants Lacking Recombination

Genetics ◽  
2003 ◽  
Vol 163 (3) ◽  
pp. 857-874 ◽  
Author(s):  
Luther Davis ◽  
Gerald R Smith
Keyword(s):  
Schizosaccharomyces Pombe ◽  
Sister Chromatid ◽  
Meiotic Recombination ◽  
Meiotic Division ◽  
General Feature ◽  
Homologous Chromosomes ◽  
Chromatid Cohesion ◽  
Homozygous Diploid ◽  
Reductional Division ◽  
Meiosis I

Abstract Physical connection between homologous chromosomes is normally required for their proper segregation to opposite poles at the first meiotic division (MI). This connection is generally provided by the combination of reciprocal recombination and sister-chromatid cohesion. In the absence of meiotic recombination, homologs are predicted to segregate randomly at MI. Here we demonstrate that in rec12 mutants of the fission yeast Schizosaccharomyces pombe, which are devoid of meiosis-induced recombination, homologs segregate to opposite poles at MI 63% of the time. Residual, Rec12-independent recombination appears insufficient to account for the observed nonrandom homolog segregation. Dyad asci are frequently produced by rec12 mutants. More than half of these dyad asci contain two viable homozygous-diploid spores, the products of a single reductional division. This set of phenotypes is shared by other S. pombe mutants that lack meiotic recombination, suggesting that nonrandom MI segregation and dyad formation are a general feature of meiosis in the absence of recombination and are not peculiar to rec12 mutants. Rec8, a meiosis-specific sister-chromatid cohesin, is required for the segregation phenotypes displayed by rec12 mutants. We propose that S. pombe possesses a system independent of recombination that promotes homolog segregation and discuss possible mechanisms.

scholarly journals Ndj1, a Telomere-Associated Protein, Promotes Meiotic Recombination in Budding Yeast

2006 ◽  
Vol 26 (10) ◽  
pp. 3683-3694 ◽  
Author(s):  
Hsin-Yen Wu ◽  
Sean M. Burgess
Keyword(s):  
Meiotic Recombination ◽  
Double Strand Breaks ◽  
Homology Search ◽  
Strand Breaks ◽  
Homologous Chromosomes ◽  
Synaptonemal Complex Formation ◽  
Strand Invasion ◽  
Double Holliday Junction ◽  
Meiosis I

ABSTRACT Dynamic telomere repositioning is a prominent feature of meiosis. Deletion of a telomere-associated protein, Ndj1, results in the failure of both attachment and clustering of telomeres at the nuclear envelope and delays several landmarks of meiosis I, such as pairing, synaptonemal complex formation, and timing of the meiosis I division. We explored the role of Ndj1 in meiotic recombination, which occurs through the formation and repair of programmed double-strand breaks. The ndj1Δ mutation allows for the formation of the first detectable strand invasion intermediate (i.e., single-end invasion) with wild-type kinetics; however, it confers a delay in the formation of the double-Holliday junction intermediate and both crossover and noncrossover products. These results challenge the widely held notion that clustering of telomeres in meiosis promotes the ability of homologous chromosomes to find one another in budding Saccharomyces cerevisiae. We propose that an Ndj1-dependent function is critical for stabilizing analogous strand invasion intermediates that exist in two separate branches of the bifurcated pathway, leading to either noncrossover or crossover formation. These findings provide a link between telomere dynamics and a distinct mechanistic step of meiotic recombination that follows the homology search.

Live observation of fission yeast meiosis in recombination-deficient mutants

2001 ◽  
Vol 114 (15) ◽  
pp. 2843-2853 ◽  
Author(s):  
Monika Molnar ◽  
Jürg Bähler ◽  
Jürg Kohli ◽  
Yasushi Hiraoka
Keyword(s):  
Fission Yeast ◽  
Chromosome Segregation ◽  
Meiotic Division ◽  
Chiasma Formation ◽  
Homologous Chromosomes ◽  
Yeast Meiosis ◽  
Mutant Cells ◽  
Random Level ◽  
Meiosis I ◽  
Chromosome Disjunction

Regular segregation of homologous chromosomes during meiotic divisions is essential for the generation of viable progeny. In recombination-proficient organisms, chromosome disjunction at meiosis I generally occurs by chiasma formation between the homologs (chiasmate meiosis). We have studied meiotic stages in living rec8 and rec7 mutant cells of fission yeast, with special attention to prophase and the first meiotic division. Both rec8 and rec7 are early recombination mutants, and in rec7 mutants, chromosome segregation at meiosis I occurs without any recombination (achiasmate meiosis). Both mutants showed distinct irregularities in nuclear prophase movements. Additionally, rec7 showed an extended first division of variable length and with single chromosomes changing back and forth between the cell poles. Two other early recombination deficient mutants (rec14 and rec15) showed very similar phenotypes to rec7 during the first meiotic division, and the fidelity of achiasmate chromosome segregation slightly exceeded the expected random level. We discuss possible regulatory mechanisms of fission yeast to deal with achiasmate chromosome segregation.

scholarly journals The Yeast Motor Protein, Kar3p, Is Essential for Meiosis I

1997 ◽  
Vol 139 (2) ◽  
pp. 459-467 ◽  
Author(s):  
Carol A. Bascom-Slack ◽  
Dean S. Dawson
Keyword(s):  
Synaptonemal Complex ◽  
Meiotic Recombination ◽  
Molecular Motor ◽  
Motor Protein ◽  
Double Strand Breaks ◽  
Wild Type ◽  
Strand Breaks ◽  
Homologous Chromosomes ◽  
Low Levels ◽  
Meiosis I

The recognition and alignment of homologous chromosomes early in meiosis is essential for their subsequent segregation at anaphase I; however, the mechanism by which this occurs is unknown. We demonstrate here that, in the absence of the molecular motor, Kar3p, meiotic cells are blocked with prophase monopolar microtubule arrays and incomplete synaptonemal complex (SC) formation. kar3 mutants exhibit very low levels of heteroallelic recombination. kar3 mutants do produce double-strand breaks that act as initiation sites for meiotic recombination in yeast, but at levels severalfold reduced from wild-type. These data are consistent with a meiotic role for Kar3p in the events that culminate in synapsis of homologues.

scholarly journals Meiotic recombination proteins localize to linear elements in Schizosaccharomyces pombe

Chromosoma ◽  
2006 ◽  
Vol 115 (4) ◽  
pp. 330-340 ◽  
Author(s):  
Alexander Lorenz ◽  
Anna Estreicher ◽  
Jürg Kohli ◽  
Josef Loidl
Keyword(s):  
Schizosaccharomyces Pombe ◽  
Meiotic Recombination ◽  
Recombination Proteins ◽  
Linear Elements

scholarly journals Mer2 binds directly to both nucleosomes and axial proteins as the keystone of meiotic recombination

2020 ◽  
Author(s):  
Dorota Rousova ◽  
Saskia K. Funk ◽  
Heidi Reichle ◽  
John R. Weir
Keyword(s):  
Sexual Reproduction ◽  
Meiotic Recombination ◽  
Dna Breaks ◽  
Homologous Chromosomes ◽  
Protein Biochemistry ◽  
Double Strand Dna Breaks ◽  
Domain Protein ◽  
Meiosis I ◽  
Double Strand Dna

One of the defining features of sexual reproduction is the recombination events that take place during meiosis I. Recombination is both evolutionarily advantageous, but also mechanistically necessary to form the crossovers that link homologous chromosomes. Meiotic recombination is initiated through the placement of programmed double-strand DNA breaks (DSBs) mediated by the protein Spo11. The timing, number, and physical placement of DSBs are carefully controlled through a variety of protein machinery. Previous work has implicated Mer2(IHO1 in mammals) to be involved in both the placement of breaks, and their timing. In this study we use a combination of protein biochemistry and biophysics to extensively characterise various roles of the Mer2. We gain further insights into the details of Mer2 interaction with the PHD protein Spp1, reveal that Mer2 is a novel nucleosome binder, and suggest how Mer2’s interaction with the HORMA domain protein Hop1 (HORMAD1/2 in mammals) is controlled.

scholarly journals Spo13 prevents premature cohesin cleavage during meiosis

2019 ◽  
Vol 4 ◽  
pp. 29 ◽  
Author(s):  
Stefan Galander ◽  
Rachael E. Barton ◽  
David A. Kelly ◽  
Adèle L. Marston
Keyword(s):  
Regulatory Subunit ◽  
Homologous Chromosomes ◽  
Sister Chromatids ◽  
Functional Homolog ◽  
Sister Kinetochore ◽  
Phosphatase 2A ◽  
Cohesin Subunit ◽  
Yeast Meiosis ◽  
Mitosis And Meiosis ◽  
Meiosis I

Background: Meiosis produces gametes through two successive nuclear divisions, meiosis I and meiosis II. In contrast to mitosis and meiosis II, where sister chromatids are segregated, during meiosis I, homologous chromosomes are segregated. This requires the monopolar attachment of sister kinetochores and the loss of cohesion from chromosome arms, but not centromeres, during meiosis I. The establishment of both sister kinetochore mono-orientation and cohesion protection rely on the budding yeast meiosis I-specific Spo13 protein, the functional homolog of fission yeast Moa1 and mouse MEIKIN. Methods: Here we investigate the effects of loss of SPO13 on cohesion during meiosis I using a live-cell imaging approach. Results: Unlike wild type, cells lacking SPO13 fail to maintain the meiosis-specific cohesin subunit, Rec8, at centromeres and segregate sister chromatids to opposite poles during anaphase I. We show that the cohesin-destabilizing factor, Wpl1, is not primarily responsible for the loss of cohesion during meiosis I. Instead, premature loss of centromeric cohesin during anaphase I in spo13Δ cells relies on separase-dependent cohesin cleavage. Further, cohesin loss in spo13Δ anaphase I cells is blocked by forcibly tethering the regulatory subunit of protein phosphatase 2A, Rts1, to Rec8. Conclusions: Our findings indicate that separase-dependent cleavage of phosphorylated Rec8 causes premature cohesin loss in spo13Δ cells.

Recombinationless meiosis in Saccharomyces cerevisiae

1981 ◽  
Vol 1 (10) ◽  
pp. 891-901
Author(s):  
R E Malone ◽  
R E Esposito
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Gene Conversion ◽  
Genetic Control ◽  
Meiotic Recombination ◽  
Meiotic Division ◽  
Crossing Over ◽  
Background Levels ◽  
Recombination System ◽  
Rad50 Gene ◽  
Meiosis I

We have utilized the single equational meiotic division conferred by the spo13-1 mutation of Saccharomyces cerevisiae (S. Klapholtz and R. E. Esposito, Genetics 96:589-611, 1980) as a technique to study the genetic control of meiotic recombination and to analyze the meiotic effects of several radiation-sensitive mutations (rad6-1, rad50-1, and rad52-1) which have been reported to reduce meiotic recombination (Game et al., Genetics 94:51-68, 1980); Prakash et al., Genetics 94:31-50, 1980). The spo13-1 mutation eliminates the meiosis I reductional segregation, but does not significantly affect other meiotic events (including recombination). Because of the unique meiosis it confers, the spo13-1 mutation provides an opportunity to recover viable meiotic products in a Rec- background. In contrast to the single rad50-1 mutant, we found that the double rad50-1 spo13-1 mutant produced viable ascospores after meiosis and sporulation. These spores were nonrecombinant: meiotic crossing-over was reduced at least 150-fold, and no increase in meiotic gene conversion was observed over mitotic background levels. The rad50-1 mutation did not, however, confer a Rec- phenotype in mitosis; rather, it increased both spontaneous crossing-over and gene conversion. The spore inviability conferred by the single rad6-1 and rad52-1 mutations was not eliminated by the presence of the spo13-1 mutation. Thus, only the rad50 gene has been unambiguously identified by analysis of viable meiotic ascospores as a component of the meiotic recombination system.

SUMOylation is required for normal development of linear elements and wild-type meiotic recombination in Schizosaccharomyces pombe

Chromosoma ◽  
2009 ◽  
Vol 119 (1) ◽  
pp. 59-72 ◽  
Author(s):  
Mario Spirek ◽  
Anna Estreicher ◽  
Edina Csaszar ◽  
Jennifer Wells ◽  
Ramsay J. McFarlane ◽  
...  
Keyword(s):  
Schizosaccharomyces Pombe ◽  
Meiotic Recombination ◽  
Normal Development ◽  
Wild Type ◽  
Linear Elements

Making crossovers during meiosis

2005 ◽  
Vol 33 (6) ◽  
pp. 1451-1455 ◽  
Author(s):  
M.C. Whitby
Keyword(s):  
Genetic Variation ◽  
Homologous Recombination ◽  
Chromosome Segregation ◽  
Meiotic Recombination ◽  
Meiotic Division ◽  
Holliday Junctions ◽  
Meiotic Spindle ◽  
Homologous Chromosomes ◽  
Dna Junctions

Homologous recombination (HR) is required to promote both correct chromosome segregation and genetic variation during meiosis. For this to be successful recombination intermediates must be resolved to generate reciprocal exchanges or ‘crossovers’ between the homologous chromosomes (homologues) during the first meiotic division. Crossover recombination promotes faithful chromosome segregation by establishing connections (chiasmata) between the homologues, which help guide their proper bipolar alignment on the meiotic spindle. Recent studies of meiotic recombination in both the budding and fission yeasts have established that there are at least two pathways for generating crossovers. One pathway involves the resolution of fully ligated four-way DNA junctions [HJs (Holliday junctions)] by an as yet unidentified endonuclease. The second pathway appears to involve the cleavage of the precursors of ligated HJs, namely displacement (D) loops and unligated/nicked HJs, by the Mus81-Eme1/Mms4 endonuclease.

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