Monopolar spindle attachment of sister chromatids is ensured by two distinct mechanisms at the first meiotic division in fission yeast

During meiosis, the kinetochore undergoes substantial reorganization to establish monopolar spindle attachment. In the fission yeast Schizosaccharomyces pombe, the KNL1–Spc7-Mis12-Nuf2 (KMN) complex, which constitutes the outer kinetochore, is disassembled during meiotic prophase and is reassembled before meiosis I. Here, we show that the nucleoporin Nup132 is required for timely assembly of the KMN proteins: In the absence of Nup132, Mis12 and Spc7 are precociously assembled at the centromeres during meiotic prophase. In contrast, Nuf2 shows timely dissociation and reappearance at the meiotic centromeres. We further demonstrate that depletion of Nup132 activates the spindle assembly checkpoint in meiosis I, possibly because of the increased incidence of erroneous spindle attachment at sister chromatids. These results suggest that precocious assembly of the kinetochores leads to the meiosis I defects observed in the nup132-disrupted mutant. Thus, we propose that Nup132 plays an important role in establishing monopolar spindle attachment at meiosis I through outer kinetochore reorganization at meiotic prophase.

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

Genetics ◽

10.1093/genetics/153.1.49 ◽

1999 ◽

Vol 153 (1) ◽

pp. 49-55 ◽

Cited By ~ 1

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.

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Ase1/Prc1-dependent spindle elongation corrects merotely during anaphase in fission yeast

The Journal of Cell Biology ◽

10.1083/jcb.200902093 ◽

2009 ◽

Vol 187 (3) ◽

pp. 399-412 ◽

Cited By ~ 36

Author(s):

Thibault Courtheoux ◽

Guillaume Gay ◽

Yannick Gachet ◽

Sylvie Tournier

Keyword(s):

Fission Yeast ◽

Mechanical Model ◽

Elongation Rate ◽

Force Balance ◽

Balance Model ◽

Spindle Poles ◽

Sister Chromatids ◽

Spindle Elongation ◽

Dependent Mechanism

Faithful segregation of sister chromatids requires the attachment of each kinetochore (Kt) to microtubules (MTs) that extend from opposite spindle poles. Merotelic Kt orientation is a Kt–MT misattachment in which a single Kt binds MTs from both spindle poles rather than just one. Genetic induction of merotelic Kt attachment during anaphase in fission yeast resulted in intra-Kt stretching followed by either correction or Kt disruption. Laser ablation of spindle MTs revealed that intra-Kt stretching and merotelic correction were dependent on MT forces. The presence of multiple merotelic chromosomes linearly antagonized the spindle elongation rate, and this phenomenon could be solved numerically using a simple force balance model. Based on the predictions of our mechanical model, we provide in vivo evidence that correction of merotelic attachment in anaphase is tension dependent and requires an Ase1/Prc1-dependent mechanism that prevents spindle collapse and thus asymmetric division and/or the appearance of the cut phenotype.

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Ndc80 Internal Loop Interacts with Dis1/TOG to Ensure Proper Kinetochore-Spindle Attachment in Fission Yeast

Current Biology ◽

10.1016/j.cub.2010.12.048 ◽

2011 ◽

Vol 21 (3) ◽

pp. 214-220 ◽

Cited By ~ 76

Author(s):

Kuo-Shun Hsu ◽

Takashi Toda

Keyword(s):

Fission Yeast ◽

Internal Loop ◽

Spindle Attachment

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Disruption of Astral Microtubule Contact with the Cell Cortex Activates a Bub1, Bub3, and Mad3-dependent Checkpoint in Fission Yeast

Molecular Biology of the Cell ◽

10.1091/mbc.e04-03-0256 ◽

2004 ◽

Vol 15 (7) ◽

pp. 3345-3356 ◽

Cited By ~ 37

Author(s):

Sylvie Tournier ◽

Yannick Gachet ◽

Vicky Buck ◽

Jeremy S. Hyams ◽

Jonathan B.A. Millar

Keyword(s):

Actin Cytoskeleton ◽

Fission Yeast ◽

Spindle Assembly Checkpoint ◽

Spindle Assembly ◽

Yeast Cells ◽

Cell Cortex ◽

Checkpoint Proteins ◽

Sister Chromatids ◽

Astral Microtubule ◽

Spindle Rotation

In animal and yeast cells, the mitotic spindle is aligned perpendicularly to the axis of cell division. This ensures that sister chromatids are separated to opposite sides of the cytokinetic actomyosin ring. In fission yeast, spindle rotation is dependent upon the interaction of astral microtubules with the cortical actin cytoskeleton. In this article, we show that addition of Latrunculin A, which prevents spindle rotation, delays the separation of sister chromatids and anaphase promoting complex-mediated destruction of spindle-associated Securin and Cyclin B. Moreover, we find that whereas sister kinetochore pairs normally congress to the spindle midzone before anaphase onset, this congression is disrupted when astral microtubule contact with the actin cytoskeleton is disturbed. By analyzing the timing of kinetochore separation, we find that this anaphase delay requires the Bub3, Mad3, and Bub1 but not the Mad1 or Mad2 spindle assembly checkpoint proteins. In agreement with this, we find that Bub1 remains associated with kinetochores when spindles are mispositioned. These data indicate that, in fission yeast, astral microtubule contact with the medial cell cortex is monitored by a subset of spindle assembly checkpoint proteins. We propose that this checkpoint ensures spindles are properly oriented before anaphase takes place.

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Inverted meiosis: an alternative way of chromosome segregation for reproduction

Acta Biochimica et Biophysica Sinica ◽

10.1093/abbs/gmaa054 ◽

2020 ◽

Vol 52 (7) ◽

pp. 702-707 ◽

Cited By ~ 1

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.

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

Molecular Biology of the Cell ◽

10.1091/mbc.e11-04-0378 ◽

2011 ◽

Vol 22 (16) ◽

pp. 2848-2861 ◽

Cited By ~ 21

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.

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A new and anomalous type of meiosis in a mantid, Callimantis antillarum saussure

Proceedings of the Royal Society of London Series B Biological Sciences ◽

10.1098/rspb.1938.0040 ◽

1938 ◽

Vol 125 (841) ◽

pp. 516-523 ◽

Cited By ~ 16

Keyword(s):

Meiotic Division ◽

Middle Part ◽

Extreme Form ◽

Diffuse Stage ◽

Spindle Attachment ◽

Meiotic Chromosomes ◽

Male Sex

The general course of meiosis in the Orthoptera is remarkably constant from species to species, and even from one suborder to another. This is at any rate true of meiosis in the male sex; owing to technical difficulties, oogenesis has been studied in only a few species, but there seems no reason to believe that it is less uniform than spermatogenesis. Such deviations from normality as do occur seem to be of two main kinds. In some species the middle part of the prophase of the first meiotic division (pachytene, and sometimes diplotene as well) are replaced by a “diffuse stage” during which the chromosomes become almost impossible to fix and stain. Such a stage is apparently present in the peculiar orthopteran Schizodactylus monstrosus (McClung and Asana 1933, 1935)-In other species the chiasmata which usually occur more or less at random along the length of the meiotic chromosomes are localized in certain definite regions. Localization of chiasmata is seen in it's most extreme form in species of the genus Mecostethus (Acrididae), where only one chiasma is usually formed in each bivalent, just near the spindle attachment (White 1936).

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Live observation of fission yeast meiosis in recombination-deficient mutants

Journal of Cell Science ◽

10.1242/jcs.114.15.2843 ◽

2001 ◽

Vol 114 (15) ◽

pp. 2843-2853 ◽

Cited By ~ 7

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.

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Estimation of meiosis and sporulation efficiencies in the fission yeast by ascus analysis

Genetics Research ◽

10.1017/s0016672300018231 ◽

1979 ◽

Vol 33 (2) ◽

pp. 109-119

Author(s):

G. B. Calleja ◽

M. Zuker ◽

Byron F. Johnson

Keyword(s):

Fission Yeast ◽

Meiotic Division ◽

Analytical Method ◽

Developmental Process ◽

Site Of Action

SUMMARYPopulations of linear asci are classified according to the number of spores in an ascus. The resultant five numerical classes are further classified into ten spatial classes according to the arrangement of the spores in an ascus and, by inference, into ten historical classes according to the number and origins of failures during the developmental process. An analysis of the observed frequencies of numerical classes allows derivation of the efficiencies of the first meiotic division, the second meiotic division and sporulation in a fission yeast. The analytical method may be useful in locating the site of action of sporulation inhibitors and in identifying meiosis mutants from sporulation mutants.

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