scholarly journals Chromosome separation during Drosophila male meiosis I requires separase-mediated cleavage of the homolog conjunction protein UNO

PLoS Genetics ◽  
2020 ◽  
Vol 16 (10) ◽  
pp. e1008928
Author(s):  
Joe Weber ◽  
Zeynep Kabakci ◽  
Soumya Chaurasia ◽  
Erich Brunner ◽  
Christian F. Lehner
Keyword(s):  
Male Meiosis ◽  
Chromosome Separation ◽  
Meiosis I

scholarly journals Bipolar spindle attachments affect redistributions of ZW10, a Drosophila centromere/kinetochore component required for accurate chromosome segregation.

1996 ◽  
Vol 134 (5) ◽  
pp. 1127-1140 ◽  
Author(s):  
B C Williams ◽  
M Gatti ◽  
M L Goldberg
Keyword(s):  
Chromosome Segregation ◽  
Male Meiosis ◽  
Chromosome Behavior ◽  
Bipolar Spindle ◽  
Chromosome Missegregation ◽  
Spindle Poles ◽  
Anaphase Onset ◽  
Sister Chromatids ◽  
Chromosome Separation ◽  
Meiosis I

Previous efforts have shown that mutations in the Drosophila ZW10 gene cause massive chromosome missegregation during mitotic divisions in several tissues. Here we demonstrate that mutations in ZW10 also disrupt chromosome behavior in male meiosis I and meiosis II, indicating that ZW10 function is common to both equational and reductional divisions. Divisions are apparently normal before anaphase onset, but ZW10 mutants exhibit lagging chromosomes and irregular chromosome segregation at anaphase. Chromosome missegregation during meiosis I of these mutants is not caused by precocious separation of sister chromatids, but rather the nondisjunction of homologs. ZW10 is first visible during prometaphase, where it localizes to the kinetochores of the bivalent chromosomes (during meiosis I) or to the sister kinetochores of dyads (during meiosis II). During metaphase of both divisions, ZW10 appears to move from the kinetochores and to spread toward the poles along what appear to be kinetochore microtubules. Redistributions of ZW10 at metaphase require bipolar attachments of individual chromosomes or paired bivalents to the spindle. At the onset of anaphase I or anaphase II, ZW10 rapidly relocalizes to the kinetochore regions of the separating chromosomes. In other mutant backgrounds in which chromosomes lag during anaphase, the presence or absence of ZW10 at a particular kinetochore predicts whether or not the chromosome moves appropriately to the spindle poles. We propose that ZW10 acts as part of, or immediately downstream of, a tension-sensing mechanism that regulates chromosome separation or movement at anaphase onset.

Role of microtubules and microtubule organizing centers on meiotic chromosome elimination in Sciara ocellaris

1997 ◽  
Vol 110 (6) ◽  
pp. 721-730 ◽  
Author(s):  
M.R. Esteban ◽  
M.C. Campos ◽  
A.L. Perondini ◽  
C. Goday
Keyword(s):  
Meiotic Chromosome ◽  
Chromosome Elimination ◽  
Male Meiosis ◽  
Meiotic Spindle ◽  
Monopolar Spindle ◽  
Meiotic Spindles ◽  
Cytoplasmic Microtubules ◽  
Spindle Microtubules ◽  
Meiosis I

Spindle formation and chromosome elimination during male meiosis in Sciara ocellaris (Diptera, Sciaridae) has been studied by immunofluorescence techniques. During meiosis I a monopolar spindle is formed from a single polar complex (centrosome-like structure). This single centrosomal structure persists during meiosis II and is responsible for the non-disjunction of the maternal X chromatids. During meiosis I and II non-spindle microtubules are assembled in the cytoplasmic bud regions of the spermatocytes. The chromosomes undergoing elimination during both meiotic divisions are segregated to the bud region where they associate with bundles of microtubules. The presence and distribution of centrosomal antigens in S. ocellaris meiotic spindles and bud regions has been investigated using different antibodies. gamma-Tubulin and centrin are present in the bud as well as in the single polar complex of first meiotic spindle. The results suggest that spermatocyte bud regions contain microtubule-organizing centres (MTOCs) that nucleate cytoplasmic microtubules that are involved in capturing chromosomes in the bud regions. The distribution of actin and myosin in the spermatocytes during meiosis is also reported.

scholarly journals Interfered Chromosome Pairing Promotes Meiosis Instability of Autotetraploid Arabidopsis by High Temperatures

2021 ◽  
Author(s):  
Huiqi Fu ◽  
Jiayi Zhao ◽  
Ziming Ren ◽  
Ke Yang ◽  
Chong Wang ◽  
...  
Keyword(s):  
Arabidopsis Thaliana ◽  
Chromosome Pairing ◽  
Environmental Temperature ◽  
Oryza Sativa L ◽  
Male Meiosis ◽  
Crossing Over ◽  
Autotetraploid Rice ◽  
Increased Temperature ◽  
Chromosome Separation ◽  
The Impact

Alterations of environmental temperature affect multiple meiosis processes in flowering plants. Polyploid plants derived from whole genome duplication (WGD) have enhanced genetic plasticity and tolerance to environmental stress, but meanwhile face a challenge for organization and segregation of doubled chromosome sets. In this study, we investigated the impact of increased environmental temperature on male meiosis in autotetraploid Arabidopsis thaliana. Under low to mildly-increased temperatures (5-28°C), irregular chromosome segregation universally takes place in synthesized autotetraploid Columbia-0 (Col-0). Similar meiosis lesions occur in autotetraploid rice (Oryza sativa L.) and allotetraploid canola (Brassica napus cv. Westar), but not in evolutionary-derived hexaploid wheat (Triticum aestivum). As temperature increases to extremely high, chromosome separation and tetrad formation are severely disordered due to univalent formation caused by suppressed crossing-over. We found a strong correlation between tetravalent formation and successful chromosome pairing, both of which are negatively correlated with temperature elevation, suggesting that increased temperature interferes with crossing-over prominently by impacting homolog pairing. Besides, we showed that loading irregularities of axis proteins ASY1 and ASY4 co-localize on the chromosomes of syn1 mutant, and the heat-stressed diploid and autotetraploid Col-0, revealing that heat stress affects lateral region of synaptonemal complex (SC) by impacting stability of axis. Moreover, we showed that chromosome axis and SC in autotetraploid Col-0 are more sensitive to increased temperature than that of diploid Arabidopsis. Taken together, our study provide evidence suggesting that WGD without evolutionary and/or natural adaption negatively affects stability and thermal tolerance of meiotic recombination in Arabidopsis thaliana.

Cold stress contributes to aberrant cytokinesis during male meiosis I in a wheat thermosensitive genic male sterile line

2010 ◽  
Vol 34 (3) ◽  
pp. 389-405 ◽  
Author(s):  
ZONGHUI TANG ◽  
LIPING ZHANG ◽  
DI YANG ◽  
CHANGPING ZHAO ◽  
YONGLIAN ZHENG
Keyword(s):  
Cold Stress ◽  
Male Meiosis ◽  
Male Sterile ◽  
Male Sterile Line ◽  
Meiosis I

scholarly journals Isolation and Cytogenetic Characterization of Male Meiotic Mutants of Drosophila melanogaster

Genetics ◽  
2004 ◽  
Vol 166 (4) ◽  
pp. 1795-1806
Author(s):  
Kazuyuki Hirai ◽  
Satomi Toyohira ◽  
Takashi Ohsako ◽  
Masa-Toshi Yamamoto
Keyword(s):  
Drosophila Melanogaster ◽  
Sex Chromosome ◽  
Male Meiosis ◽  
Fourth Chromosome ◽  
Homologous Chromosomes ◽  
Meiotic Mutants ◽  
Chromatid Cohesion ◽  
Cytogenetic Characterization ◽  
Meiosis I

Abstract Proper segregation of homologous chromosomes in meiosis I is ensured by pairing of homologs and maintenance of sister chromatid cohesion. In male Drosophila melanogaster, meiosis is achiasmatic and homologs pair at limited chromosome regions called pairing sites. We screened for male meiotic mutants to identify genes required for normal pairing and disjunction of homologs. Nondisjunction of the sex and the fourth chromosomes in male meiosis was scored as a mutant phenotype. We screened 2306 mutagenized and 226 natural population-derived second and third chromosomes and obtained seven mutants representing different loci on the second chromosome and one on the third. Five mutants showed relatively mild effects (<10% nondisjunction). mei(2)yh149 and mei(2)yoh7134 affected both the sex and the fourth chromosomes, mei(2)yh217 produced possible sex chromosome-specific nondisjunction, and mei(2)yh15 and mei(2)yh137 produced fourth chromosome-specific nondisjunction. mei(2)yh137 was allelic to the teflon gene required for autosomal pairing. Three mutants exhibited severe defects, producing >10% nondisjunction of the sex and/or the fourth chromosomes. mei(2)ys91 (a new allele of the orientation disruptor gene) and mei(3)M20 induced precocious separation of sister chromatids as early as prometaphase I. mei(2)yh92 predominantly induced nondisjunction at meiosis I that appeared to be the consequence of failure of the separation of paired homologous chromosomes.

scholarly journals Paternal chromosome elimination and X non-disjunction on asymmetric spindles in Sciara male meiosis

2021 ◽  
Author(s):  
Brigitte de Saint Phalle ◽  
Rudolf Oldenbourg ◽  
Donna F. Kubai ◽  
Edward D. Salmon ◽  
Susan A. Gerbi
Keyword(s):  
Amorphous Material ◽  
Metaphase Plate ◽  
Chromosome Elimination ◽  
Male Meiosis ◽  
Paternal Chromosome ◽  
Bipolar Spindle ◽  
Monopolar Spindle ◽  
A Cell ◽  
Chromosome Imprinting ◽  
Meiosis I

Meiosis in male Sciara is unique with a single centrosome. A monopolar spindle forms in meiosis I, but a bipolar spindle forms in meiosis II. The imprinted paternal chromosomes are eliminated in meiosis I; there is non-disjunction of the X in meiosis II. Despite differences in spindle construction and chromosome behavior, both meiotic divisions are asymmetric, producing a cell and a small bud. Observations of live spermatocytes made with the LC-PolScope, differential interference contrast optics and fluorescence revealed maternal and paternal chromosome sets on the monopolar spindle in meiosis I and formation of an asymmetric monastral bipolar spindle in meiosis II where all chromosomes except the X congress to the metaphase plate. The X remains near the centrosome after meiosis I and stays with it as the spindle forms in meiosis II. Electron microscopy revealed amorphous material between the X and the centrosome. Immunofluorescence with an antibody against the checkpoint protein Mad2 stains the centromeres of the maternal X dyad in late meiosis I and in meiosis II where it fails to congress to the metaphase plate. Mad2 is also present throughout the paternal chromosomes destined for elimination in meiosis I, suggesting a possible role in chromosome imprinting. If Mad2 on the X dyad mediates a spindle checkpoint in meiosis II, it may delay metaphase to facilitate formation of the second half spindle through a non-centrosomal mechanism.

scholarly journals Sex chromosome pairing mediated by euchromatic homology in Drosophila male meiosis

2019 ◽  
Author(s):  
Christopher A. Hylton ◽  
Katie Hansen ◽  
Andrew Bourgeois ◽  
John E. Tomkiel
Keyword(s):  
Sex Chromosomes ◽  
Sex Chromosome ◽  
Intergenic Spacer ◽  
Male Meiosis ◽  
Early Prophase ◽  
Dna Breaks ◽  
Late Prophase ◽  
Prophase I ◽  
Y Chromosomes ◽  
Meiosis I

ABSTRACTTo maintain proper ploidy, haploid sex cells must undergo two subsequent meiotic divisions. During meiosis I, homologs pair and remain conjoined until segregation at anaphase. Drosophila melanogaster spermatocytes are unique in that the canonical events of meiosis I including synaptonemal complex (SC) formation, double-strand DNA breaks, and chiasmata are absent. Sex chromosomes pair at intergenic spacer sequences within the heterochromatic rDNA while euchromatin is required to pair and segregate autosomal homologies, suggesting that pairing may be limited to specific sequences. However, previous work generated from genetic segregation assays or observations of late prophase I/prometaphase I chromosome associations fail to differentiate pairing from conjunction. Here, we separately examined the capability of X euchromatin to pair and conjoin using an rDNA-deficient X and a series of Dp(1;Y) chromosomes. Genetic assays showed that duplicated X euchromatin can substitute for endogenous rDNA pairing sites. Segregation was not proportional to homology length, and pairing could be mapped to nonoverlapping sequences within a single Dp(1;Y). Using fluorescent in situ hybridization (FISH) to early prophase I spermatocytes, we showed that pairing occurred with high fidelity at all homologies tested. Pairing was unaffected by the presence of X rDNA, nor could it be explained by rDNA magnification. By comparing genetic and cytological data, we determined that centromere proximal pairings were best at segregation. Segregation was dependent on the conjunction protein Stromalin in Meiosis while the autosomal-specific Teflon was dispensable. Overall, our results suggest that pairing may occur at all homologies, but there may be sequence or positional requirements for conjunction.ARTICLE SUMMARYDrosophila males have evolved a unique system of chromosome segregation in meiosis that lacks recombination. Chromosomes pair at selected sequences suggesting that early steps of meiosis may also differ in this organism. Using Y chromosomes carrying portions of X material, we show that pairing between sex chromosomes can be mediated by sequences other than the previously identified rDNA pairing sites. We propose that pairing may simply be homology-based and may not differ from canonical meiosis observed in females. The main difference in males may be that conjunctive mechanisms that join homologs in the absence of crossovers.

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