THE EFFECT OF THE GENOTYPE OF TRITICUM SPELTOIDES ON THE PAIRING OF HOMOLOGOUS CHROMOSOMES

1973 ◽  
Vol 15 (2) ◽  
pp. 233-236 ◽  
Author(s):  
Jørgen Larsen ◽  
Gordon Kimber
Keyword(s):  
Chromosome Pairing ◽  
Chiasma Frequency ◽  
Homologous Chromosome ◽  
Homologous Chromosomes ◽  
Homologous Chromosome Pairing

Two lines of Triticum speltoides that affect chromosome pairing in hybrids with T. aestivum were treated with colchicine and autotetraploid sectors were induced. The chromosome pairing and chiasma frequency of the diploid lines and the induced autotetraploids were recorded. No differences were detected between the diploids or between the autotetraploids. It is concluded that the genotype of the low-pairing line of T. speltoides does not reduce homologous chromosome pairing and, therefore, the low pairing observed in hybrids of this line and T. aestivum must be taken to indicate a lack of homology between the chromosomes of T. speltoides and T. aestivum.

Initiation of homologous chromosome pairing during meiosis

2006 ◽  
Vol 34 (4) ◽  
pp. 545-549 ◽  
Author(s):  
P. Jordan
Keyword(s):  
Dna Replication ◽  
Chromosome Pairing ◽  
Homologous Chromosome ◽  
Recent Progress ◽  
Checkpoint Proteins ◽  
Homologous Chromosomes ◽  
Homologous Chromosome Pairing ◽  
Number Of Factors ◽  
Axial Element ◽  
Meiosis I

Following pre-meiotic DNA replication, homologous chromosomes must be paired and become tightly linked to ensure reductional segregation during meiosis I. Therefore initiation of homologous chromosome pairing is vital for meiosis to proceed correctly. A number of factors contribute to the initiation of homologous chromosome pairing including telomere and centromere dynamics, pairing centres, checkpoint proteins and components of the axial element. The present review briefly summarizes recent progress in our understanding of initiation of homologous chromosome pairing during meiosis and discusses the differences that are observed between research organisms.

scholarly journals The telomere bouquet is a hub where meiotic double-strand breaks, synapsis, and stable homolog juxtaposition are coordinated in the zebrafish, Danio rerio

2018 ◽  
Author(s):  
Yana P. Blokhina ◽  
An D. Nguyen ◽  
Bruce W. Draper ◽  
Sean M. Burgess
Keyword(s):  
Chromosome Pairing ◽  
Danio Rerio ◽  
Genetic Information ◽  
Homologous Chromosome ◽  
Double Strand Breaks ◽  
Early Prophase ◽  
Strand Breaks ◽  
Homologous Chromosomes ◽  
Homologous Chromosome Pairing ◽  
Males And Females

AbstractMeiosis is a cellular program that generates haploid gametes for sexual reproduction. While chromosome events that contribute to reducing ploidy (homologous chromosome pairing, synapsis, and recombination) are well conserved, their execution varies across species and even between sexes of the same species. The telomere bouquet is a conserved feature of meiosis that was first described nearly a century ago, yet its role is still debated. Here we took advantage of the prominent telomere bouquet in zebrafish, Danio rerio, and super-resolution microscopy to show that axis morphogenesis, synapsis, and the formation of double-strand breaks (DSBs) all take place within the immediate vicinity of telomeres. We established a coherent timeline of events and tested the dependence of each event on the formation of Spo11-induced DSBs. First, we found that the axis protein Sycp3 loads adjacent to telomeres and extends inward, suggesting a specific feature common to all telomeres seeds the development of the axis. Second, we found that newly formed axes near telomeres engage in presynaptic co-alignment by a mechanism that depends on DSBs, even when stable juxtaposition of homologous chromosomes at interstitial regions is not yet evident. Third, we were surprised to discover that ~30% of telomeres in early prophase I engage in associations between two or more chromosome ends and these interactions decrease in later stages. Finally, while pairing and synapsis were disrupted in both spo11 males and females, their reproductive phenotypes were starkly different; spo11 mutant males failed to produce sperm while females produced offspring with severe developmental defects. Our results support zebrafish as an important vertebrate model for meiosis with implications for differences in fertility and genetically derived birth defects in males and females.Author SummaryInherent to reproduction is the transmission of genetic information from one generation to the next. In sexually reproducing organisms, each parent contributes an equal amount of genetic information, packaged in chromosomes, to the offspring. Diploid organisms, like humans, have two copies of every chromosome, while their haploid gametes (e.g. eggs and sperm) have only one. This reduction in ploidy depends on the segregation of chromosomes during meiosis, resulting in gametes with one copy of each chromosome. Missegregation of the chromosomes in the parents leads to abnormal chromosome numbers in the offspring, which is usually lethal or has detrimental developmental effects. While it has been known for over a century that homologous chromosomes pair and recombine to facilitate proper segregation, how homologs find their partners has remained elusive. A structure that has been central to the discussion of homolog pairing is the bouquet, or the dynamic clustering of telomeres during early stages of meiosis. Here we use zebrafish to show that the telomere bouquet is the site where key events leading to homologous chromosome pairing are coordinated. Furthermore, we show that deletion of spo11, a gene required for proper recombination in most studied organisms, resulted in very different effects in males and females where males were sterile while females produced deformed progeny.

Non-homologous chromosome pairing during meiosis in haploid Brassica rapa

2021 ◽  
Author(s):  
Jiachen Yuan ◽  
Gongyao Shi ◽  
Yan Yang ◽  
Janeen Braynen ◽  
Xinjie Shi ◽  
...  
Keyword(s):  
Brassica Rapa ◽  
Chromosome Pairing ◽  
Homologous Chromosome ◽  
Homologous Chromosome Pairing

scholarly journals Regulating chromosomal movement by the cochaperone FKB-6 ensures timely pairing and synapsis

2017 ◽  
Vol 216 (2) ◽  
pp. 393-408 ◽  
Author(s):  
Benjamin Alleva ◽  
Nathan Balukoff ◽  
Amy Peiper ◽  
Sarit Smolikove
Keyword(s):  
Nuclear Envelope ◽  
Chromosome Pairing ◽  
Meiotic Prophase ◽  
Homologous Chromosome ◽  
Strand Break ◽  
Crossing Over ◽  
Chromosome Movement ◽  
Microtubule Network ◽  
Homologous Chromosome Pairing ◽  
Proper Movement

In meiotic prophase I, homologous chromosome pairing is promoted through chromosome movement mediated by nuclear envelope proteins, microtubules, and dynein. After proper homologue pairing has been established, the synaptonemal complex (SC) assembles along the paired homologues, stabilizing their interaction and allowing for crossing over to occur. Previous studies have shown that perturbing chromosome movement leads to pairing defects and SC polycomplex formation. We show that FKB-6 plays a role in SC assembly and is required for timely pairing and proper double-strand break repair kinetics. FKB-6 localizes outside the nucleus, and in its absence, the microtubule network is altered. FKB-6 is required for proper movement of dynein, increasing resting time between movements. Attenuating chromosomal movement in fkb-6 mutants partially restores the defects in synapsis, in agreement with FKB-6 acting by decreasing chromosomal movement. Therefore, we suggest that FKB-6 plays a role in regulating dynein movement by preventing excess chromosome movement, which is essential for proper SC assembly and homologous chromosome pairing.

A cohesin-based structural platform supporting homologous chromosome pairing in meiosis

2016 ◽  
Vol 62 (3) ◽  
pp. 499-502 ◽  
Author(s):  
Da-Qiao Ding ◽  
Tokuko Haraguchi ◽  
Yasushi Hiraoka
Keyword(s):  
Chromosome Pairing ◽  
Homologous Chromosome ◽  
Homologous Chromosome Pairing

Homologous chromosome pairing in meiosis of higher eukaryotes—still an enigma?

Genome ◽  
2020 ◽  
Vol 63 (10) ◽  
pp. 469-482
Author(s):  
J. Sybenga
Keyword(s):  
Chromosome Pairing ◽  
Dna Sequences ◽  
Homologous Chromosome ◽  
Homology Search ◽  
Size Difference ◽  
Primary Role ◽  
Dna Double Strand Breaks ◽  
Homologous Chromosome Pairing ◽  
Higher Eukaryotes

Meiosis is the basis of the generative reproduction of eukaryotes. The crucial first step is homologous chromosome pairing. In higher eukaryotes, micrometer-scale chromosomes, micrometer distances apart, are brought together by nanometer DNA sequences, at least a factor of 1000 size difference. Models of homology search, homologue movement, and pairing at the DNA level in higher eukaryotes are primarily based on studies with yeast where the emphasis is on the induction and repair of DNA double-strand breaks (DSB). For such a model, the very large nuclei of most plants and animals present serious problems. Homology search without DSBs cannot be explained by models based on DSB repair. The movement of homologues to meet each other and make contact at the molecular level is not understood. These problems are discussed and the conclusion is that at present practically nothing is known of meiotic homologue pairing in higher eukaryotes up to the formation of the synaptonemal complex, and that new, necessarily speculative models must be developed. Arguments are given that RNA plays a central role in homology search and a tentative model involving RNA in homology search is presented. A role of actin in homologue movement is proposed. The primary role of DSBs in higher eukaryotes is concluded to not be in pairing but in the preparation of Holliday junctions, ultimately leading to chromatid exchange.

OsSPO11-1 is essential for both homologous chromosome pairing and crossover formation in rice

Chromosoma ◽  
2010 ◽  
Vol 119 (6) ◽  
pp. 625-636 ◽  
Author(s):  
Hengxiu Yu ◽  
Mo Wang ◽  
Ding Tang ◽  
Kejian Wang ◽  
Fuli Chen ◽  
...  
Keyword(s):  
Chromosome Pairing ◽  
Homologous Chromosome ◽  
Homologous Chromosome Pairing

Homologous chromosome pairing inSchizosaccharomyces pombe

Yeast ◽  
2006 ◽  
Vol 23 (13) ◽  
pp. 977-989 ◽  
Author(s):  
Jennifer L. Wells ◽  
David W. Pryce ◽  
Ramsay J. McFarlane
Keyword(s):  
Chromosome Pairing ◽  
Homologous Chromosome ◽  
Homologous Chromosome Pairing
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