END-TO-END, CHAIN-LIKE ASSOCIATIONS OF PAIRED PACHYTENE CHROMOSOMES OF CREPIS CAPILLARIS

1969 ◽  
Vol 11 (2) ◽  
pp. 403-408 ◽  
Author(s):  
E. B. Wagenaar ◽  
R. S. Sadasivaiah
Keyword(s):  
Meiotic Prophase ◽  
Pachytene Stage ◽  
Homologous Chromosomes ◽  
Crepis Capillaris ◽  
Interphase Cells ◽  
Chromosome Associations ◽  
End To End

Studies on the pachytene stage of meiosis of Crepis capillaris showed that the paired chromosomes are attached end-to-end forming chain-like configurations. The arrangements of the chromosomes in these tandem associations are according to the expectations based on the somatogram of this species. These observations make it very likely that the end-to-end chromosome associations present in all somatic interphase cells (Wagenaar, 1969) have their primary significance in the recognition and pairing of homologous chromosomes during early meiotic prophase.

END-TO-END ATTACHMENT OF HAPLOID CHROMOSOMES OF ORNITHOGALUM VIRENS

1972 ◽  
Vol 14 (3) ◽  
pp. 716-717 ◽  
Author(s):  
Terry Ashley ◽  
E. B. Wagenaar
Keyword(s):  
Meiotic Prophase ◽  
General Property ◽  
Somatic Cells ◽  
Open Chain ◽  
Haploid Nucleus ◽  
Homologous Chromosomes ◽  
Plant Chromosomes ◽  
Ring Configuration ◽  
End To End ◽  
Ornithogalum Virens

The three prophase chromosomes in the haploid nucleus of Ornithogalum virens pollen are attached end-to-end in an open chain. This lends support to the suggestion that the ring configuration, in which homologous chromosomes lie opposite one another in somatic cells, is involved in recognition and pairing of homologues during meiotic prophase. It is also suggested that affinity of ends may be a general property of plant chromosomes.

TELOMERIC ASSOCIATIONS OF GAMETIC AND SOMATIC CHROMOSOMES IN DIPLOID AND AUTOTETRAPLOID ORNITHOGALUM VIRENS

1974 ◽  
Vol 16 (1) ◽  
pp. 61-76 ◽  
Author(s):  
Terry Ashley ◽  
E. B. Wagenaar
Keyword(s):  
Meiotic Prophase ◽  
Pollen Grain ◽  
Root Tip ◽  
Open Chain ◽  
Homologous Chromosomes ◽  
End To End ◽  
A Chain ◽  
Diploid Cells ◽  
Ornithogalum Virens ◽  
Haploid Pollen

In acetocarmine root-tip squashes, diploid cells of Ornithogalum virens in prophase exhibit configurations resulting from end-to-end associations of the six chromosomes. Homologues lie opposite one another in a ring. Prophase chromosomes of the autotretraploid cells likewise associate end-to-end; however, four homogues instead of two generally lie adjacent to one another and four (or eight) ends are often connected instead of the two (or four) found in diploid cells. Prophase chromosomes in a haploid pollen grain of a diploid form an open chain of three chromosomes, whereas in pollen from the autotetraploid balanced gametes form a configuration in which homologous pairs lie adjacent to one another and are attached end-to-end to other homologous pairs of nonhomologous chromosomes to form a chain. These observations are discussed in terms of the role telomeric associations may play in recognition and pairing of homologous chromosomes during meiotic prophase. This recognition of homologues may occur as early as syngamy.

scholarly journals Lateral Elements Inside Synaptonemal Complex-Like Polycomplexes in ndt80 Mutants of Yeast Bind DNA

Genetics ◽  
2003 ◽  
Vol 163 (2) ◽  
pp. 539-544 ◽  
Author(s):  
Hasanuzzaman Bhuiyan ◽  
Gunilla Dahlfors ◽  
Karin Schmekel
Keyword(s):  
In Situ Hybridization ◽  
Electron Microscope ◽  
Synaptonemal Complex ◽  
Immunoelectron Microscopy ◽  
Meiotic Prophase ◽  
Lateral Element ◽  
Homologous Chromosomes ◽  
Meiotic Prophase I ◽  
Dna Antibodies

Abstract The synaptonemal complex (SC) keeps the synapsed homologous chromosomes together during pachytene in meiotic prophase I. Structures that resemble stacks of SCs, polycomplexes, are sometimes found before or after pachytene. We have investigated ndt80 mutants of yeast, which arrest in pachytene. SCs appear normal in spread chromosome preparations, but are only occasionally found in intact nuclei examined in the electron microscope. Instead, large polycomplexes occur in almost every ndt80 mutant nucleus. Immunoelectron microscopy using DNA antibodies show strong preferential labeling to the lateral element parts of the polycomplexes. In situ hybridization using chromosome-specific probes confirms that the chromosomes in ndt80 mutants are paired and attached to the SCs. Our results suggest that polycomplexes can be involved in binding of chromosomes and possibly also in synapsis.

The testis-specific transcript (ferT) of the tyrosine kinase FER is expressed during spermatogenesis in a stage-specific manner

1990 ◽  
Vol 10 (9) ◽  
pp. 5021-5025
Author(s):  
E Keshet ◽  
A Itin ◽  
K Fischman ◽  
U Nir
Keyword(s):  
In Situ Hybridization ◽  
Tyrosine Kinase ◽  
Tyrosine Kinases ◽  
Meiotic Prophase ◽  
Hybridization Analysis ◽  
Pachytene Stage ◽  
Specific Transcript ◽  
Specific Manner

ferT is a testis-specific transcript of FER encoding a truncated version of the potential tyrosine kinase. Using in situ hybridization analysis, we found that ferT was transiently expressed during spermatogenesis and that expression was restricted to spermatocytes at the pachytene stage of meiotic prophase. This pattern of expression is unprecedented by other tyrosine kinases and suggests a role for ferT in a particular stage of spermatogenesis.

scholarly journals Synaptonemal complex antigen location and conservation.

1987 ◽  
Vol 105 (1) ◽  
pp. 93-103 ◽  
Author(s):  
P B Moens ◽  
C Heyting ◽  
A J Dietrich ◽  
W van Raamsdonk ◽  
Q Chen
Keyword(s):  
Chromosome Pairing ◽  
Meiotic Prophase ◽  
Structural Integrity ◽  
Genetic Recombination ◽  
Positive Control ◽  
Western Blots ◽  
Lateral Element ◽  
Homologous Chromosomes ◽  
Recombination Nodules ◽  
Grain Distribution

The axial cores of chromosomes in the meiotic prophase nuclei of most sexually reproducing organisms play a pivotal role in the arrangement of chromatin, in the synapsis of homologous chromosomes, in the process of genetic recombination, and in the disjunction of chromosomes. We report an immunogold analysis of the axial cores and the synaptonemal complexes (SC) using two mouse monoclonal antibodies raised against isolated rat SCs. In Western blots of purified SCs, antibody II52F10 recognizes a 30- and a 33-kD peptide (Heyting, C., P. B. Moens, W. van Raamsdonk, A. J. J. Dietrich, A. C. G. Vink, and E. J. W. Redeker, 1987, Eur. J. Cell Biol., 43: 148-154). In spreads of rat spermatocyte nuclei it produces gold grains over the cores of autosomal and sex chromosomes. The cores label lightly during the chromosome pairing stage (zygotene) of early meiotic prophase and they become more intensely labeled when they are parallel aligned as the lateral elements of the SC during pachytene (55 grains/micron SC). Statistical analysis of electronically recorded gold grain positions shows that the two means of the bimodal gold grain distribution coincide with the centers of the lateral elements. At diplotene, when the cores separate, the antigen is still detected along the length of the core and the enlarged ends are heavily labeled. Shadow-cast SC preparations show that recombination nodules are not labeled. The continued presence suggests that the antigens serve a continuing function in the cores, such as chromatin binding, and/or structural integrity. Antibody III15B8, which does not recognize the 30- and 33-kD peptides, produces gold grains predominantly between the lateral elements. The grain distribution is bimodal with the mean of each peak just inside the pairing face of the lateral element. The antigen is present where and while the cores of the homologous chromosomes are paired. From the location and the timing, it is assumed that the antigen recognized by III15B8 functions in chromosome pairing at meiotic prophase. The two anti-rat SC antibodies label rat and mouse SCs but not rabbit or dog SCs. A positive control using human CREST (calcinosis, Raynaud's phenomenon, esophageal dysmotility, sclerodactyly, telangiectasia) anti-centromere serum gives equivalent labeling of SC centromeres in the rat, mouse, rabbit, and dog. It is concluded that the SC antigens recognized by II52F10 and III15B8 are not widely conserved. The two antibodies do not bind to cellular or nuclear components of somatic cells.(ABSTRACT TRUNCATED AT 400 WORDS)

scholarly journals Identification of a meiosis-specific chromosome movement pattern induced by persistent DNA damage

2020 ◽  
Author(s):  
Daniel León-Periñán ◽  
Alfonso Fernández-Álvarez
Keyword(s):  
Dna Damage ◽  
Meiotic Prophase ◽  
Meiotic Chromosome ◽  
Three Dimensional ◽  
Model Organism ◽  
Movement Pattern ◽  
Time Lapse ◽  
Chromosome Movement ◽  
Nuclear Movement ◽  
Chromosome Associations

ABSTRACTAs one of the main events occurring during meiotic prophase, the dynamics of meiotic chromosome movement is not yet well understood. Currently, although it is well-established that chromosome movement takes an important role during meiotic recombination promoting the pairing between homologous chromosomes and avoiding excessive chromosome associations, it is mostly unclear whether those movements follow a particular fixed pattern, or are stochastically distributed. Using Schizosaccharomyces pombe as a model organism, which exhibits dramatic meiotic nuclear oscillations, we have developed a computationally automatized statistical analysis of three-dimensional time-lapse fluorescence information in order to characterize nuclear trajectories and morphological patterns during meiotic prophase. This approach allowed us to identify a patterned oscillatory microvariation during the meiotic nuclear motion. Additionally, we showed evidence suggesting that this unexpected oscillatory motif might be due to the detection of persistent DNA damage during the nuclear movement, supporting how the nucleus also regulates its oscillations. Our computationally automatized tool will be useful for the identification of new patterns of nuclear oscillations during gametogenesis.

scholarly journals Mammalian Protein SCP1 Forms Synaptonemal Complex-like Structures in the Absence of Meiotic Chromosomes

2005 ◽  
Vol 16 (1) ◽  
pp. 212-217 ◽  
Author(s):  
Rupert Öllinger ◽  
Manfred Alsheimer ◽  
Ricardo Benavente
Keyword(s):  
Chromosome Segregation ◽  
Meiotic Prophase ◽  
Experimental Conditions ◽  
Homologous Chromosomes ◽  
Meiotic Chromosomes ◽  
Heterologous System ◽  
Primary Determinant ◽  
Specific Proteins ◽  
Mammalian Protein

Synaptonemal complexes (SCs) are evolutionary conserved, meiosis-specific structures that play a central role in synapsis of homologous chromosomes, chiasmata distribution, and chromosome segregation. However, it is still for the most part unclear how SCs do assemble during meiotic prophase. Major components of mammalian SCs are the meiosis-specific proteins SCP1, 2, and 3. To investigate the role of SCP1 in SC assembly, we expressed SCP1 in a heterologous system, i.e., in COS-7 cells that normally do not express SC proteins. Notably, under these experimental conditions SCP1 is able to form structures that closely resemble SCs (i.e., polycomplexes). Moreover, we show that mutations that modify the length of the central α-helical domain of SCP1 influence the width of polycomplexes. Finally, we demonstrate that deletions of the nonhelical N- or C-termini both affect polycomplex assembly, although in a different manner. We conclude that SCP1 is a primary determinant of SC assembly that plays a key role in synapsis of homologous chromosomes.

scholarly journals Polyploidy Induces Centromere Association

2000 ◽  
Vol 148 (2) ◽  
pp. 233-238 ◽  
Author(s):  
Enrique Martinez-Perez ◽  
Peter J. Shaw ◽  
Graham Moore
Keyword(s):  
Gene Expression ◽  
Meiotic Prophase ◽  
Diploid Species ◽  
Major Effect ◽  
Anther Development ◽  
Polyploid Species ◽  
Homologous Chromosomes ◽  
Gamete Formation ◽  
Affect Gene Expression ◽  
Segregation Of Chromosomes

Many species exhibit polyploidy. The presence of more than one diploid set of similar chromosomes in polyploids can affect the assortment of homologous chromosomes, resulting in unbalanced gametes. Therefore, a mechanism is required to ensure the correct assortment and segregation of chromosomes for gamete formation. Ploidy has been shown to affect gene expression. We present in this study an example of a major effect on a phenotype induced by ploidy within the Triticeae. We demonstrate that centromeres associate early during anther development in polyploid species. In contrast, centromeres in diploid species only associate at the onset of meiotic prophase. We propose that this mechanism provides a potential route by which chromosomes can start to be sorted before meiosis in polyploids. This explains previous reports indicating that meiotic prophase is shorter in polyploids than in their diploid progenitors. Even artificial polyploids exhibit this phenotype, suggesting that the mechanism must be present in diploids, but only expressed in the presence of more than one diploid set of chromosomes.

Cytogenetics of decaploid Agropyron elongatum (Elytrigia elongata) (2n = 70). I. Frequency of decavalent formation

Genome ◽  
1990 ◽  
Vol 33 (6) ◽  
pp. 811-817 ◽  
Author(s):  
Mikio Muramatsu
Keyword(s):  
High Frequency ◽  
Chromosome Association ◽  
Agropyron Elongatum ◽  
Homologous Chromosomes ◽  
Ring Shape ◽  
Meiotic Configuration ◽  
Multivalent Formation ◽  
A Cell ◽  
Chromosome Associations ◽  
Metaphase I

The multivalents that appeared in the decaploid strain of Agropyron elongatum (2n = 10x = 70), a relative of wheat, ranged from trivalent to decavalent. Few univalents occurred. The metaphase I chromosome association in 12 cells where all configurations could clearly be identified averaged 0.42 ring X + 0.17 chain X + 0.42 ring VIII + 0.17 branched VIII + 0.25 chain VIII + 0.17 chain VII + 1.17 ring VI + 0.33 branched VI + 0.5 chain VI + 1.67 ring IV + 0.42 branched IV + 0.58 chain IV + 0.08 branched III + 0.17 chain III + 12.58 ring II + 3.75 open II + 0.25 I. The occurrence of decavalents, up to two in one cell, and of a cell with five multivalents, each of which involved more than five chromosomes, and many multivalents of ring shape indicated that the strain is autodecaploid.The chromosome associations of each cell can be interpreted as seven groups of 10 homologous chromosomes. The high frequency of bivalents indicated a tendency toward reduced multivalent formation, for which an explanation is suggested.Key words: Agropyron elongatum, meiotic configuration, decaploid, multivalent.

scholarly journals akirin is required for diakinesis bivalent structure and synaptonemal complex disassembly at meiotic prophase I

2013 ◽  
Vol 24 (7) ◽  
pp. 1053-1067 ◽  
Author(s):  
Amy M. Clemons ◽  
Heather M. Brockway ◽  
Yizhi Yin ◽  
Bhavatharini Kasinathan ◽  
Yaron S. Butterfield ◽  
...  
Keyword(s):  
Synaptonemal Complex ◽  
Meiotic Prophase ◽  
Chromosome Condensation ◽  
Late Prophase ◽  
Homologous Chromosomes ◽  
Prophase I ◽  
Meiotic Prophase I ◽  
Evolutionarily Conserved ◽  
Key Events

During meiosis, evolutionarily conserved mechanisms regulate chromosome remodeling, leading to the formation of a tight bivalent structure. This bivalent, a linked pair of homologous chromosomes, is essential for proper chromosome segregation in meiosis. The formation of a tight bivalent involves chromosome condensation and restructuring around the crossover. The synaptonemal complex (SC), which mediates homologous chromosome association before crossover formation, disassembles concurrently with increased condensation during bivalent remodeling. Both chromosome condensation and SC disassembly are likely critical steps in acquiring functional bivalent structure. The mechanisms controlling SC disassembly, however, remain unclear. Here we identify akir-1 as a gene involved in key events of meiotic prophase I in Caenorhabditis elegans. AKIR-1 is a protein conserved among metazoans that lacks any previously known function in meiosis. We show that akir-1 mutants exhibit severe meiotic defects in late prophase I, including improper disassembly of the SC and aberrant chromosome condensation, independently of the condensin complexes. These late-prophase defects then lead to aberrant reconfiguring of the bivalent. The meiotic divisions are delayed in akir-1 mutants and are accompanied by lagging chromosomes. Our analysis therefore provides evidence for an important role of proper SC disassembly in configuring a functional bivalent structure.

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