Centromere Mapping Functions for Aneuploid Meiotic Products: Analysis of rec8, rec10 and rec11 Mutants of the Fission Yeast Schizosaccharomyces pombe

Genetics ◽  
1999 ◽  
Vol 153 (1) ◽  
pp. 49-55 ◽  
Author(s):  
Michelle D Krawchuk ◽  
Wayne P Wahls
Keyword(s):  
Fission Yeast ◽  
Chromosome Segregation ◽  
Sister Chromatid ◽  
Meiotic Division ◽  
Homologous Chromosomes ◽  
Mapping Functions ◽  
Sister Chromatids ◽  
Chromatid Cohesion ◽  
Products Analysis ◽  
Meiosis I

AbstractRecent evidence suggests that the position of reciprocal recombination events (crossovers) is important for the segregation of homologous chromosomes during meiosis I and sister chromatids during meiosis II. We developed genetic mapping functions that permit the simultaneous analysis of centromere-proximal crossover recombination and the type of segregation error leading to aneuploidy. The mapping functions were tested in a study of the rec8, rec10, and rec11 mutants of fission yeast. In each mutant we monitored each of the three chromosome pairs. Between 38 and 100% of the chromosome segregation errors in the rec8 mutants were due to meiosis I nondisjunction of homologous chromosomes. The remaining segregation errors were likely the result of precocious separation of sister chromatids, a previously described defect in the rec8 mutants. Between 47 and 100% of segregation errors in the rec10 and rec11 mutants were due to nondisjunction of sister chromatids during meiosis II. In addition, centromere-proximal recombination was reduced as much as 14-fold or more on chromosomes that had experienced nondisjunction. These results demonstrate the utility of the new mapping functions and support models in which sister chromatid cohesion and crossover position are important determinants for proper chromosome segregation in each meiotic division.

scholarly journals Cohesins Determine the Attachment Manner of Kinetochores to Spindle Microtubules at Meiosis I in Fission Yeast

2003 ◽  
Vol 23 (11) ◽  
pp. 3965-3973 ◽  
Author(s):  
Shihori Yokobayashi ◽  
Masayuki Yamamoto ◽  
Yoshinori Watanabe
Keyword(s):  
Fission Yeast ◽  
Chromosome Segregation ◽  
Sister Chromatid ◽  
Specific Requirement ◽  
Spindle Poles ◽  
Chromatid Cohesion ◽  
Spindle Microtubules ◽  
Yeast Meiosis ◽  
Meiosis I ◽  
Random Division

ABSTRACT During mitosis, sister kinetochores attach to microtubules that extend to opposite spindle poles (bipolar attachment) and pull the chromatids apart at anaphase (equational segregation). A multisubunit complex called cohesin, including Rad21/Scc1, plays a crucial role in sister chromatid cohesion and equational segregation at mitosis. Meiosis I differs from mitosis in having a reductional pattern of chromosome segregation, in which sister kinetochores are attached to the same spindle (monopolar attachment). During meiosis, Rad21/Scc1 is largely replaced by its meiotic counterpart, Rec8. If Rec8 is inactivated in fission yeast, meiosis I is shifted from reductional to equational division. However, the reason rec8Δ cells undergo equational rather than random division has not been clarified; therefore, it has been unclear whether equational segregation is due to a loss of cohesin in general or to a loss of a specific requirement for Rec8. We report here that the equational segregation at meiosis I depends on substitutive Rad21, which relocates to the centromeres if Rec8 is absent. Moreover, we demonstrate that even if sufficient amounts of Rad21 are transferred to the centromeres at meiosis I, thereby establishing cohesion at the centromeres, rec8Δ cells never recover monopolar attachment but instead secure bipolar attachment. Thus, Rec8 and Rad21 define monopolar and bipolar attachment, respectively, at meiosis I. We conclude that cohesin is a crucial determinant of the attachment manner of kinetochores to the spindle microtubules at meiosis I in fission yeast.

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 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 Direct evaluation of cohesin-mediated sister kinetochore associations at meiosis I in fission yeast

2021 ◽  
Author(s):  
Masashi Nambu ◽  
Atsuki Kishikawa ◽  
Takatomi Yamada ◽  
Kento Ichikawa ◽  
Yunosuke Kira ◽  
...  
Keyword(s):  
Fission Yeast ◽  
Chromosome Segregation ◽  
Mitotic Chromosomes ◽  
Direct Evaluation ◽  
Homologous Chromosomes ◽  
Sister Chromatids ◽  
Pheromone Signaling ◽  
Sister Kinetochore ◽  
Novel Method ◽  
Meiosis I

Kinetochores drive chromosome segregation by mediating chromosome interactions with the spindle. In higher eukaryotes, sister kinetochores are separately positioned on opposite sides of sister centromeres during mitosis, but associate with each other during meiosis I. Kinetochore association facilitates the attachment of sister chromatids to the same pole, enabling the segregation of homologous chromosomes toward opposite poles. In the fission yeast, Schizosaccharomyces pombe, Rec8-containing meiotic cohesin is suggested to establish kinetochore associations by mediating cohesion of the centromere cores. However, cohesin-mediated kinetochore associations on intact chromosomes have never been demonstrated directly. Here, we describe a novel method for the direct evaluation of kinetochore associations on intact chromosomes in live S. pombe cells, and demonstrate that sister kinetochores and the centromere cores are positioned separately on mitotic chromosomes but associate with each other on meiosis I chromosomes. Furthermore, we demonstrate that kinetochore association depends on meiotic cohesin and the cohesin regulators, Moa1 and Mrc1, and requires mating-pheromone signaling for its establishment. These results confirm cohesin-mediated kinetochore association and its regulatory mechanisms, along with the usefulness of the developed method for its analysis.

scholarly journals Multiple Subunits of the Caenorhabditis elegans Anaphase-Promoting Complex Are Required for Chromosome Segregation During Meiosis I

Genetics ◽  
2002 ◽  
Vol 160 (2) ◽  
pp. 805-813 ◽  
Author(s):  
Edward S Davis ◽  
Lucia Wille ◽  
Barry A Chestnut ◽  
Penny L Sadler ◽  
Diane C Shakes ◽  
...  
Keyword(s):  
Rna Interference ◽  
Caenorhabditis Elegans ◽  
Chromosome Segregation ◽  
Sister Chromatid ◽  
Sister Chromatid Cohesion ◽  
Anaphase Promoting Complex ◽  
Genetic Screens ◽  
Chromatid Cohesion ◽  
Interference Studies ◽  
Meiosis I

Abstract Two genes, originally identified in genetic screens for Caenorhabditis elegans mutants that arrest in metaphase of meiosis I, prove to encode subunits of the anaphase-promoting complex or cyclosome (APC/C). RNA interference studies reveal that these and other APC/C subunits are essential for the segregation of chromosomal homologs during meiosis I. Further, chromosome segregation during meiosis I requires APC/C functions in addition to the release of sister chromatid cohesion.

scholarly journals Double or nothing: a Drosophila mutation affecting meiotic chromosome segregation in both females and males.

Genetics ◽  
1994 ◽  
Vol 136 (3) ◽  
pp. 953-964 ◽  
Author(s):  
D P Moore ◽  
W Y Miyazaki ◽  
J E Tomkiel ◽  
T L Orr-Weaver
Keyword(s):  
Cell Death ◽  
Chromosome Segregation ◽  
Sister Chromatid ◽  
Meiotic Chromosome ◽  
Sister Chromatid Cohesion ◽  
Aberrant Chromosome ◽  
Chromatid Cohesion ◽  
Meiotic Nondisjunction ◽  
Lethal Allele ◽  
Meiosis I

Abstract We describe a Drosophila mutation, Double or nothing (Dub), that causes meiotic nondisjunction in a conditional, dominant manner. Previously isolated mutations in Drosophila specifically affect meiosis either in females or males, with the exception of the mei-S332 and ord genes which are required for proper sister-chromatid cohesion. Dub is unusual in that it causes aberrant chromosome segregation almost exclusively in meiosis I in both sexes. In Dub mutant females both nonexchange and exchange chromosomes undergo nondisjunction, but the effect of Dub on nonexchange chromosomes is more pronounced. Dub reduces recombination levels slightly. Multiple nondisjoined chromosomes frequently cosegregate to the same pole. Dub results in nondisjunction of all chromosomes in meiosis I of males, although the levels are lower than in females. When homozygous, Dub is a conditional lethal allele and exhibits phenotypes consistent with cell death.

scholarly journals SOLO: a meiotic protein required for centromere cohesion, coorientation, and SMC1 localization in Drosophila melanogaster

2010 ◽  
Vol 188 (3) ◽  
pp. 335-349 ◽  
Author(s):  
Rihui Yan ◽  
Sharon E. Thomas ◽  
Jui-He Tsai ◽  
Yukihiro Yamada ◽  
Bruce D. McKee
Keyword(s):  
Drosophila Melanogaster ◽  
Sister Chromatid ◽  
Sister Chromatid Cohesion ◽  
Early Prophase ◽  
Wild Type ◽  
Sister Chromatids ◽  
Chromatid Cohesion ◽  
Mutant Phenotypes ◽  
Meiosis I ◽  
Novel Protein

Sister chromatid cohesion is essential to maintain stable connections between homologues and sister chromatids during meiosis and to establish correct centromere orientation patterns on the meiosis I and II spindles. However, the meiotic cohesion apparatus in Drosophila melanogaster remains largely uncharacterized. We describe a novel protein, sisters on the loose (SOLO), which is essential for meiotic cohesion in Drosophila. In solo mutants, sister centromeres separate before prometaphase I, disrupting meiosis I centromere orientation and causing nondisjunction of both homologous and sister chromatids. Centromeric foci of the cohesin protein SMC1 are absent in solo mutants at all meiotic stages. SOLO and SMC1 colocalize to meiotic centromeres from early prophase I until anaphase II in wild-type males, but both proteins disappear prematurely at anaphase I in mutants for mei-S332, which encodes the Drosophila homologue of the cohesin protector protein shugoshin. The solo mutant phenotypes and the localization patterns of SOLO and SMC1 indicate that they function together to maintain sister chromatid cohesion in Drosophila meiosis.

scholarly journals Inverted meiosis: an alternative way of chromosome segregation for reproduction

2020 ◽  
Vol 52 (7) ◽  
pp. 702-707 ◽  
Author(s):  
Wenzhu Li ◽  
Xiangwei He
Keyword(s):  
Dna Replication ◽  
Fission Yeast ◽  
Chromosome Segregation ◽  
Chromosome Structure ◽  
Adaptive Strategy ◽  
Homologous Chromosomes ◽  
Working Model ◽  
Sister Chromatids ◽  
Holocentric Chromosome ◽  
Inverted Order

Abstract Canonical meiosis is characterized by two sequential rounds of nuclear divisions following one round of DNA replication—reductional segregation of homologous chromosomes during the first division and equational segregation of sister chromatids during the second division. Meiosis in an inverted order of two nuclear divisions—inverted meiosis has been observed in several species with holocentromeres as an adaptive strategy to overcome the obstacle in executing a canonical meiosis due to the holocentric chromosome structure. Recent findings of co-existence of inverted and canonical meiosis in two monocentric organisms, human and fission yeast, suggested that inverted meiosis could be common and also lead to the puzzle regarding the mechanistic feasibility for executing two meiosis programs simultaneously. Here, we discuss apparent conflicts for concurrent canonical meiosis and inverted meiosis. Furthermore, we attempt to provide a working model that may be compatible for both forms of meiosis.

scholarly journals The spindle checkpoint protein Mad2 regulates APC/C activity during prometaphase and metaphase of meiosis I in Saccharomyces cerevisiae

2011 ◽  
Vol 22 (16) ◽  
pp. 2848-2861 ◽  
Author(s):  
Dai Tsuchiya ◽  
Claire Gonzalez ◽  
Soni Lacefield
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Cell Cycle ◽  
Chromosome Segregation ◽  
Meiotic Division ◽  
Spindle Checkpoint ◽  
Yeast Cells ◽  
Meiotic Cell ◽  
Checkpoint Protein ◽  
Sister Chromatids ◽  
Meiosis I

In many eukaryotes, disruption of the spindle checkpoint protein Mad2 results in an increase in meiosis I nondisjunction, suggesting that Mad2 has a conserved role in ensuring faithful chromosome segregation in meiosis. To characterize the meiotic function of Mad2, we analyzed individual budding yeast cells undergoing meiosis. We find that Mad2 sets the duration of meiosis I by regulating the activity of APCCdc20. In the absence of Mad2, most cells undergo both meiotic divisions, but securin, a substrate of the APC/C, is degraded prematurely, and prometaphase I/metaphase I is accelerated. Some mad2Δ cells have a misregulation of meiotic cell cycle events and undergo a single aberrant division in which sister chromatids separate. In these cells, both APCCdc20 and APCAma1 are prematurely active, and meiosis I and meiosis II events occur in a single meiotic division. We show that Mad2 indirectly regulates APCAma1 activity by decreasing APCCdc20 activity. We propose that Mad2 is an important meiotic cell cycle regulator that ensures the timely degradation of APC/C substrates and the proper orchestration of the meiotic divisions.

scholarly journals Rec8p, a Meiotic Recombination and Sister Chromatid Cohesion Phosphoprotein of the Rad21p Family Conserved from Fission Yeast to Humans

1999 ◽  
Vol 19 (5) ◽  
pp. 3515-3528 ◽  
Author(s):  
Sandro Parisi ◽  
Michael J. McKay ◽  
Monika Molnar ◽  
M. Anne Thompson ◽  
Peter J. van der Spek ◽  
...  
Keyword(s):  
Fission Yeast ◽  
Sister Chromatid ◽  
Germ Line ◽  
Sequence Similarity ◽  
Sister Chromatid Cohesion ◽  
Specific Expression ◽  
Chromatid Cohesion ◽  
Prophase Nucleus ◽  
Chromosome Iii ◽  
Meiosis I

ABSTRACT Our work and that of others defined mitosis-specific (Rad21 subfamily) and meiosis-specific (Rec8 subfamily) proteins involved in sister chromatid cohesion in several eukaryotes, including humans. Mutation of the fission yeast Schizosaccharomyces pombe rec8 gene was previously shown to confer a number of meiotic phenotypes, including strong reduction of recombination frequencies in the central region of chromosome III, absence of linear element polymerization, reduced pairing of homologous chromosomes, reduced sister chromatid cohesion, aberrant chromosome segregation, defects in spore formation, and reduced spore viability. Here we extend the description of recombination reduction to the central regions of chromosomes I and II. We show at the protein level that expression ofrec8 is meiosis specific and that Rec8p localizes to approximately 100 foci per prophase nucleus. Rec8p was present in an unphosphorylated form early in meiotic prophase but was phosphorylated prior to meiosis I, as demonstrated by analysis of the mei4mutant blocked before meiosis I. Evidence for the persistence of Rec8p beyond meiosis I was obtained by analysis of the mutantmes1 blocked before meiosis II. A human gene, which we designate hrec8, showed significant primary sequence similarity to rec8 and was mapped to chromosome 14. High mRNA expression of mouse and human rec8 genes was found only in germ line cells, specifically in testes and, interestingly, in spermatids. hrec8 was also expressed at a low level in the thymus. Sequence similarity and testis-specific expression indicate evolutionarily conserved functions of Rec8p in meiosis. Possible roles of Rec8p in the integration of different meiotic events are discussed.

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