Chromosome segregation into the spermatozoa of two men heterozygous for different reciprocal translocations

1983 ◽  
Vol 63 (4) ◽  
pp. 345-348 ◽  
Author(s):  
W. Balkan ◽  
R. H. Martin
Keyword(s):  
Chromosome Segregation ◽  
Reciprocal Translocations

Analysis of chromosome segregation in reciprocal translocation carriers

2020 ◽  
pp. 16-18
Author(s):  
З.Н. Тонян ◽  
И.Л. Пуппо ◽  
А.Ф. Сайфитдинова ◽  
Ю.А. Логинова ◽  
О. Г. Чиряева ◽  
...  
Keyword(s):  
Genetic Counseling ◽  
Chromosome Segregation ◽  
Birth Defects ◽  
Reciprocal Translocation ◽  
Spontaneous Abortions ◽  
Meiotic Segregation ◽  
Cleavage Stage ◽  
Reciprocal Translocations ◽  
Recurrent Spontaneous Abortions ◽  
Increased Risk

Аутосомные реципрокные транслокации (АРТ) приводят к повышенному риску образования несбалансированных гамет вследствие патологической сегрегации хромосом в мейозе у носителей. В настоящей статье приведены результаты анализа типов сегрегации для 26 АРТ, а также определены теоретически возможные варианты сегрегации хромосом. В 73% случаев у носителей АРТ в более, чем 50% бластомеров наблюдалось совпадение теоретического и детектируемого типов сегрегации. Полученные данные можно использовать для оптимизации персонализированного медико-генетического консультирования семей, где один из супругов является носителем АРТ, и имеющих репродуктивные проблемы, высокий риск неразвивающейся беременности и/или рождения ребенка с хромосомной патологией. Autosomal reciprocal translocations (ART) lead to an increased risk of imbalanced gametes formation due to pathological meiotic segregation. Segregation type was analyzed and theoretical segregation pattern was determined in 26 cleavage stage embryos in this article. A coincidence of theoretical and detectable segregation types was observed in more than 50 % of blastomeres in 73 % of cases. The data obtained may be used for personalized genetic counseling in families with high risks of recurrent spontaneous abortions, infertility or children with birth defects due to ART.

Incomplete pole orientation of kinetochores in complex meiotic metaphase I configurations delays metaphase–anaphase transition in Secale

Genome ◽  
2014 ◽  
Vol 57 (4) ◽  
pp. 233-238
Author(s):  
J. Sybenga
Keyword(s):  
Chromosome Segregation ◽  
Secale Cereale ◽  
Anther Development ◽  
Meiotic Metaphase ◽  
Mild Form ◽  
Reciprocal Translocations ◽  
Chromatid Cohesion ◽  
Pole Orientation ◽  
Metaphase I

To prevent unbalanced chromosome segregation, meiotic metaphase I – anaphase I transition is carefully regulated by delaying anaphase until all kinetochores are well oriented (anaphase checkpoint) in mammals and insects. In plants this has not yet been established. In heterozygotes of two reciprocal translocations of Secale cereale, with one chromosome replaced by its two telocentric arms, anaphase delay was correlated with the orientation of the kinetochores of the complex of five chromosomes. The terminal kinetochores of the half chromosomes were readily elongated and pole oriented. Chains of five chromosomes with all five kinetochores orienting on alternate poles where the first to start anaphase. Kinetochores of two adjacent chromosomes when oriented on the same pole were partly shielded and less well pole directed. Anaphase was delayed. Cells with this configuration accumulated during anther development. Kinetochores in metacentric chromosomes lacking chiasmata in one arm (in trivalents and bivalents) were slightly better pole oriented and delayed anaphase less. Release of chromatid cohesion as triggered by kinetochore stretch is apparently delayed by inadequate exposition and pole orientation of the kinetochores. It is a mild form of an anaphase checkpoint, in normal material synchronizing bivalent segregation.

Meiotic Crossing Over Between Nonhomologous Chromosomes Affects Chromosome Segregation in Yeast

Genetics ◽  
1997 ◽  
Vol 146 (1) ◽  
pp. 69-78
Author(s):  
Sue Jinks-Robertson ◽  
Shariq Sayeed ◽  
Tamara Murphy
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Gene Conversion ◽  
Chromosome Segregation ◽  
Meiotic Recombination ◽  
Southern Blot Analysis ◽  
Meiotic Chromosome ◽  
Crossing Over ◽  
Yeast Saccharomyces Cerevisiae ◽  
Reciprocal Translocations ◽  
Ectopic Recombination

Meiotic recombination between artificial repeats positioned on nonhomologous chromosomes occurs efficiently in the yeast Saccharomyces cerevisiae. Both gene conversion and crossover eventS have been observed, with crossovers yielding reciprocal translocations. In the current study, 5.5-kb ura3 repeats positioned on chromosomes V and XV were used to examine the effect of ectopic recombination on meiotic chromosome segregation. Ura+ random spores were selected and gene conversion vs. crossover events were distinguished by Southern blot analysis. Approximately 15% of the crossover events between chromosomes V and XV were associated with missegregation of one of these chromosomes. The missegregation was manifest as hyperploid spores containing either both translocations plus a normal chromosome, or both normal chromosomes plus one of the translocations. In those cases where it could be analyzed, missegregation occurred at the first meiotic division. These data are discussed in terms of a model in which ectopic crossovers compete efficiently with normal allelic crossovers in directing meiotic chromosome segregation.

scholarly journals Induced Chromosomal Exchange Directs the Segregation of Recombinant Chromatids in Mitosis of Drosophila

Genetics ◽  
1998 ◽  
Vol 150 (1) ◽  
pp. 173-188 ◽  
Author(s):  
Kelly J Beumer ◽  
Sergio Pimpinelli ◽  
Kent G Golic
Keyword(s):  
Chromosome Segregation ◽  
Sister Chromatid ◽  
Evolutionary Relationship ◽  
Genetic Exchange ◽  
Cytological Evidence ◽  
Reciprocal Translocations ◽  
Chromatid Segregation ◽  
Proximal Site ◽  
Chromatid Cohesion ◽  
Mitosis And Meiosis

Abstract In meiosis, the segregation of chromosomes at the reductional division is accomplished by first linking homologs together. Genetic exchange generates the bivalents that direct regular chromosome segregation. We show that genetic exchange in mitosis also generates bivalents and that these bivalents direct mitotic chromosome segregation. After FLP-mediated homologous recombination in G2 of the cell cycle, recombinant chromatids consistently segregate away from each other (x segregation). This pattern of segregation also applies to exchange between heterologs. Most, or all, cases of non-x segregation are the result of exchange in G1. Cytological evidence is presented that confirms the existence of the bivalents that direct this pattern of segregation. Our results implicate sister chromatid cohesion in maintenance of the bivalent. The pattern of chromatid segregation can be altered by providing an additional FRT at a more proximal site on one chromosome. We propose that sister chromatid exchange occurs at the more proximal site, allowing the recombinant chromatids to segregate together. This also allowed the recovery of reciprocal translocations following FLP-mediated heterologous recombination. The observation that exchange can generate a bivalent in mitotic divisions provides support for a simple evolutionary relationship between mitosis and meiosis.

Meiotic CENP-C is a shepherd: bridging the space between the centromere and the kinetochore in time and space

2020 ◽  
Vol 64 (2) ◽  
pp. 251-261
Author(s):  
Jessica E. Fellmeth ◽  
Kim S. McKim
Keyword(s):  
Chromosome Segregation ◽  
New Technologies ◽  
Early Prophase ◽  
Unique Role ◽  
Kinetochore Assembly ◽  
M Phase ◽  
In Vivo Analysis ◽  
Meiosis I

Abstract While many of the proteins involved in the mitotic centromere and kinetochore are conserved in meiosis, they often gain a novel function due to the unique needs of homolog segregation during meiosis I (MI). CENP-C is a critical component of the centromere for kinetochore assembly in mitosis. Recent work, however, has highlighted the unique features of meiotic CENP-C. Centromere establishment and stability require CENP-C loading at the centromere for CENP-A function. Pre-meiotic loading of proteins necessary for homolog recombination as well as cohesion also rely on CENP-C, as do the main scaffolding components of the kinetochore. Much of this work relies on new technologies that enable in vivo analysis of meiosis like never before. Here, we strive to highlight the unique role of this highly conserved centromere protein that loads on to centromeres prior to M-phase onset, but continues to perform critical functions through chromosome segregation. CENP-C is not merely a structural link between the centromere and the kinetochore, but also a functional one joining the processes of early prophase homolog synapsis to late metaphase kinetochore assembly and signaling.

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