scholarly journals Increased Expression of Maturation Promoting Factor Components Speeds Up Meiosis in Oocytes from Aged Females

2018 ◽  
Vol 19 (9) ◽  
pp. 2841 ◽  
Author(s):  
Marketa Koncicka ◽  
Anna Tetkova ◽  
Denisa Jansova ◽  
Edgar Del Llano ◽  
Lenka Gahurova ◽  
...  
Keyword(s):  
Chromosome Segregation ◽  
Maternal Age ◽  
Germ Line ◽  
Nuclear Lamina ◽  
Nuclear Envelope Breakdown ◽  
Meiotic Progression ◽  
Translational Activity ◽  
Female Germ Line ◽  
Mammalian Female ◽  
Meiosis I

The rate of chromosome segregation errors that emerge during meiosis I in the mammalian female germ line are known to increase with maternal age; however, little is known about the underlying molecular mechanism. The objective of this study was to analyze meiotic progression of mouse oocytes in relation to maternal age. Using the mouse as a model system, we analyzed the timing of nuclear envelope breakdown and the morphology of the nuclear lamina of oocytes obtained from young (2 months old) and aged females (12 months old). Oocytes obtained from older females display a significantly faster progression through meiosis I compared to the ones obtained from younger females. Furthermore, in oocytes from aged females, lamin A/C structures exhibit rapid phosphorylation and dissociation. Additionally, we also found an increased abundance of MPF components and increased translation of factors controlling translational activity in the oocytes of aged females. In conclusion, the elevated MPF activity observed in aged female oocytes affects precocious meiotic processes that can multifactorially contribute to chromosomal errors in meiosis I.

Chromosome segregation at meiosis I in female T(2;4)1G�/+ mice: no evidence for a decreased crossover frequency with maternal age

Chromosoma ◽  
1987 ◽  
Vol 95 (1) ◽  
pp. 1-7 ◽  
Author(s):  
Friedrich Beermann ◽  
Iris Bartels ◽  
Ulrich Franke ◽  
Ingo Hansmann
Keyword(s):  
Chromosome Segregation ◽  
Maternal Age ◽  
Crossover Frequency ◽  
Meiosis I

scholarly journals Nonrandom chromosome arrangements in germ line nuclei of Sciara coprophila males: the basis for nonrandom chromosome segregation on the meiosis I spindle.

1987 ◽  
Vol 105 (6) ◽  
pp. 2433-2446 ◽  
Author(s):  
D F Kubai
Keyword(s):  
Chromosome Segregation ◽  
Direct Evidence ◽  
Germ Line ◽  
Chromosome Translocation ◽  
Chromosome Behavior ◽  
Direct Role ◽  
Nonrandom Distribution ◽  
Chromosome Arrangements ◽  
Meiotic Spindles ◽  
Meiosis I

Meiosis I in males of the Dipteran Sciara coprophila results in the nonrandom distribution of maternally and paternally derived chromosome sets to the two division products. Based on an earlier study (Kubai, D.F. 1982. J. Cell Biol. 93:655-669), I suggested that the meiosis I spindle does not play a direct role in the nonrandom sorting of chromosomes but that, instead, haploid sets are already separated in prophase nuclei well before the onset of spindle formation. Here I report more direct evidence that this hypothesis is true; this evidence was gained from ultrastructural reconstruction analyses of the arrangement of chromosomes in germ line nuclei (prophase nuclei in spermatogonia and spermatocytes) of males heterozygous for an X-autosome chromosome translocation. Because of this translocation, the maternal and paternal chromosome sets are distinguishable, so it is possible to demonstrate that (a) the two haploid chromosome sets occupy distinct maternal and paternal nuclear compartments and that (b) nuclei are oriented so that the two haploid chromosome sets have consistent relationships to a well-defined cellular axis. The consequences of such nonrandom aspects of nuclear structure for chromosome behavior on premeiotic and meiotic spindles are discussed.

scholarly journals Spatial and temporal control of targeting Polo-like kinase during meiotic prophase

2020 ◽  
Vol 219 (11) ◽  
Author(s):  
James N. Brandt ◽  
Katarzyna A. Hussey ◽  
Yumi Kim
Keyword(s):  
Chromosome Segregation ◽  
Meiotic Prophase ◽  
Meiotic Chromosome ◽  
Holocentric Chromosomes ◽  
Cyclin Dependent Kinase ◽  
Chromosome Dynamics ◽  
C Elegans ◽  
Meiotic Progression ◽  
Crossover Site ◽  
Meiosis I

Polo-like kinases (PLKs) play widely conserved roles in orchestrating meiotic chromosome dynamics. However, how PLKs are targeted to distinct subcellular localizations during meiotic progression remains poorly understood. Here, we demonstrate that the cyclin-dependent kinase CDK-1 primes the recruitment of PLK-2 to the synaptonemal complex (SC) through phosphorylation of SYP-1 in C. elegans. SYP-1 phosphorylation by CDK-1 occurs just before meiotic onset. However, PLK-2 docking to the SC is prevented by the nucleoplasmic HAL-2/3 complex until crossover designation, which constrains PLK-2 to special chromosomal regions known as pairing centers to ensure proper homologue pairing and synapsis. PLK-2 is targeted to crossover sites primed by CDK-1 and spreads along the SC by reinforcing SYP-1 phosphorylation on one side of each crossover only when threshold levels of crossovers are generated. Thus, the integration of chromosome-autonomous signaling and a nucleus-wide crossover-counting mechanism partitions holocentric chromosomes relative to the crossover site, which ultimately defines the pattern of chromosome segregation during meiosis I.

scholarly journals Oxidative stress in oocytes during midprophase induces premature loss of cohesion and chromosome segregation errors

2016 ◽  
Vol 113 (44) ◽  
pp. E6823-E6830 ◽  
Author(s):  
Adrienne T. Perkins ◽  
Thomas M. Das ◽  
Lauren C. Panzera ◽  
Sharon E. Bickel
Keyword(s):  
Oxidative Stress ◽  
Oxidative Damage ◽  
Chromosome Segregation ◽  
Maternal Age ◽  
Meiotic Chromosome ◽  
Age Effect ◽  
Fish Analysis ◽  
Maternal Age Effect ◽  
Meiosis I

In humans, errors in meiotic chromosome segregation that produce aneuploid gametes increase dramatically as women age, a phenomenon termed the “maternal age effect.” During meiosis, cohesion between sister chromatids keeps recombinant homologs physically attached and premature loss of cohesion can lead to missegregation of homologs during meiosis I. A growing body of evidence suggests that meiotic cohesion deteriorates as oocytes age and contributes to the maternal age effect. One hallmark of aging cells is an increase in oxidative damage caused by reactive oxygen species (ROS). Therefore, increased oxidative damage in older oocytes may be one of the factors that leads to premature loss of cohesion and segregation errors. To test this hypothesis, we used an RNAi strategy to induce oxidative stress in Drosophila oocytes and measured the fidelity of chromosome segregation during meiosis. Knockdown of either the cytoplasmic or mitochondrial ROS scavenger superoxide dismutase (SOD) caused a significant increase in segregation errors, and heterozygosity for an smc1 deletion enhanced this phenotype. FISH analysis indicated that SOD knockdown moderately increased the percentage of oocytes with arm cohesion defects. Consistent with premature loss of arm cohesion and destabilization of chiasmata, the frequency at which recombinant homologs missegregate during meiosis I is significantly greater in SOD knockdown oocytes than in controls. Together these results provide an in vivo demonstration that oxidative stress during meiotic prophase induces chromosome segregation errors and support the model that accelerated loss of cohesion in aging human oocytes is caused, at least in part, by oxidative damage.

Dicer in the mammalian female germ line

2007 ◽  
Vol 8 (5) ◽  
pp. 327-327
Author(s):  
Carrie Patis
Keyword(s):  
Germ Line ◽  
Female Germ Line ◽  
Mammalian Female

scholarly journals Microtubule Assembly and Pole Coalescence: Early Steps in C. elegans Oocyte Meiosis I Spindle Assembly

2020 ◽  
Author(s):  
Chien-Hui Chuang ◽  
Aleesa J. Schlientz ◽  
Jie Yang ◽  
Bruce Bowerman
Keyword(s):  
Molecular Mechanisms ◽  
Spindle Assembly ◽  
Nuclear Lamina ◽  
Spindle Pole ◽  
Microtubule Assembly ◽  
Bipolar Structure ◽  
C Elegans ◽  
Nuclear Envelope Breakdown ◽  
Oocyte Meiosis ◽  
Meiosis I

ABSTRACTHow oocytes assemble bipolar meiotic spindles in the absence of centrosomes as microtubule organizing centers remains poorly understood. We have used live cell imaging in C. elegans to investigate requirements for the nuclear lamina and for conserved regulators of microtubule dynamics during oocyte meiosis I spindle assembly, assessing these requirements with respect to recently identified spindle assembly steps. We show that the nuclear lamina is required for microtubule bundles to form a cage-like structure that appears shortly after oocyte nuclear envelope breakdown and surrounds the oocyte chromosomes, although bipolar spindles still assembled in its absence. Although two conserved regulators of microtubule nucleation, RAN-1 and γ-tubulin, are not required for bipolar spindle assembly, both contribute to normal levels of spindle-associated microtubules and spindle assembly dynamics. Finally, the XMAP215 ortholog ZYG-9 and the nearly identical minus-end directed kinesins KLP-15/16 are required for proper assembly of the early cage-like structure of microtubule bundles, and for early spindle pole foci to coalesce into a bipolar structure. Our results provide a framework for assigning molecular mechanisms to recently described steps in C. elegans oocyte meiosis I spindle assembly.

scholarly journals Oxidative Stress Induces Telomere Dysfunction and Shortening in Human Oocytes of Advanced Age Donors

Cells ◽  
2021 ◽  
Vol 10 (8) ◽  
pp. 1866
Author(s):  
Paweł Kordowitzki
Keyword(s):  
Maternal Age ◽  
Replicative Senescence ◽  
Germ Line ◽  
Developed Countries ◽  
Telomere Shortening ◽  
Telomere Attrition ◽  
The Past ◽  
Dividing Cells ◽  
Female Germ Line ◽  
Chromosomal Instabilities

Research from the past decades provided strong evidence that in humans the pool of oocytes starts to decline already before the birth of a female individual, and from menarche to menopause the oocyte is exposed to different environmental stimuli. Since more and more women of the 21st century in developed countries wish to postpone the first pregnancy to their thirties, higher rates of miscarriage and chromosomal non-disjunction might occur. In oocytes of advanced maternal age, meaning above 35 years of age, characteristics such as chromosomal instabilities/abnormalities, spindle defects, decreased mitochondrial function and telomere shortening become more prevalent than in younger counterparts. Telomere attrition belongs to the so-called “hallmarks of aging” which are also relevant for the female germ-line cells. In oocytes, telomeres shorten with advancing maternal age due to the effects of reactive oxygen species and not upon replicative senescence, similar to how it is common in dividing cells.

scholarly journals Distinct classes of lagging chromosome underpin age-related oocyte aneuploidy in mouse

2021 ◽  
Author(s):  
Aleksandar I. Mihajlović ◽  
Jenna Haverfield ◽  
Greg FitzHarris
Keyword(s):  
Cell Cycle ◽  
Chromosome Segregation ◽  
Maternal Age ◽  
Class Ii ◽  
Class I ◽  
Mouse Oocytes ◽  
Age Related ◽  
Lagging Chromosome ◽  
Segregation Phenomenon ◽  
Meiosis I

SUMMARYChromosome segregation errors that cause oocyte aneuploidy increase in frequency with maternal age and are considered a major contributing factor of age-related fertility decline in females. A common age-associated chromosome segregation phenomenon in oocytes is the lagging anaphase chromosome, but whether anaphase laggards actually missegregate and cause aneuploidy is unclear. Here we show unexpectedly that lagging chromosomes in mouse oocytes comprise two mechanistically distinct classes of motion that we refer to as ‘Class-I’ and ‘Class-II’. We use imaging approaches and mechanistic interventions to dissociate the two classes, and find that whereas Class-II laggards are benign, Class-I laggards can directly cause aneuploidy. Most notably, a controlled prolongation of meiosis-I specifically lessens Class-I lagging to prevent aneuploidy. Our data thus reveal lagging chromosomes to be a cause of age-related aneuploidy in mouse oocytes and suggest that manipulating the cell cycle could increase the yield of useful oocytes in some contexts.

scholarly journals Microtubule assembly and pole coalescence: early steps in Caenorhabditiselegans oocyte meiosis I spindle assembly

Biology Open ◽  
2020 ◽  
Vol 9 (6) ◽  
pp. bio052308
Author(s):  
Chien-Hui Chuang ◽  
Aleesa J. Schlientz ◽  
Jie Yang ◽  
Bruce Bowerman
Keyword(s):  
Molecular Mechanisms ◽  
Spindle Assembly ◽  
Nuclear Lamina ◽  
Spindle Pole ◽  
Microtubule Assembly ◽  
Bipolar Structure ◽  
C Elegans ◽  
Nuclear Envelope Breakdown ◽  
Oocyte Meiosis ◽  
Meiosis I

ABSTRACTHow oocytes assemble bipolar meiotic spindles in the absence of centrosomes as microtubule organizing centers remains poorly understood. We have used live cell imaging in Caenorhabditis elegans to investigate requirements for the nuclear lamina and for conserved regulators of microtubule dynamics during oocyte meiosis I spindle assembly, assessing these requirements with respect to recently identified spindle assembly steps. We show that the nuclear lamina is required for microtubule bundles to form a peripheral cage-like structure that appears shortly after oocyte nuclear envelope breakdown and surrounds the oocyte chromosomes, although bipolar spindles still assembled in its absence. Although two conserved regulators of microtubule nucleation, RAN-1 and γ-tubulin, are not required for bipolar spindle assembly, both contribute to normal levels of spindle-associated microtubules and spindle assembly dynamics. Finally, the XMAP215 ortholog ZYG-9 and the nearly identical minus-end directed kinesins KLP-15/16 are required for proper assembly of the early cage-like structure of microtubule bundles, and for early spindle pole foci to coalesce into a bipolar structure. Our results provide a framework for assigning molecular mechanisms to recently described steps in C. elegans oocyte meiosis I spindle assembly.

scholarly journals Increased CDK1 activity determines the timing of kinetochore-microtubule attachments in meiosis I

2013 ◽  
Vol 202 (2) ◽  
pp. 221-229 ◽  
Author(s):  
Olga Davydenko ◽  
Richard M. Schultz ◽  
Michael A. Lampson
Keyword(s):  
Cell Division ◽  
Chromosome Segregation ◽  
Mitotic Spindle ◽  
Partial Reduction ◽  
Slow Increase ◽  
Spindle Formation ◽  
Bipolar Spindle ◽  
Nuclear Envelope Breakdown ◽  
Spindle Microtubules ◽  
Meiosis I

Chromosome segregation during cell division depends on stable attachment of kinetochores to spindle microtubules. Mitotic spindle formation and kinetochore–microtubule (K-MT) capture typically occur within minutes of nuclear envelope breakdown. In contrast, during meiosis I in mouse oocytes, formation of the acentrosomal bipolar spindle takes 3–4 h, and stabilization of K-MT attachments is delayed an additional 3–4 h. The mechanism responsible for this delay, which likely prevents stabilization of erroneous attachments during spindle formation, is unknown. Here we show that during meiosis I, attachments are regulated by CDK1 activity, which gradually increases through prometaphase and metaphase I. Partial reduction of CDK1 activity delayed formation of stable attachments, whereas a premature increase in CDK1 activity led to precocious formation of stable attachments and eventually lagging chromosomes at anaphase I. These results indicate that the slow increase in CDK1 activity in meiosis I acts as a timing mechanism to allow stable K-MT attachments only after bipolar spindle formation, thus preventing attachment errors.

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