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

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.

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In situ localization of two repetitive DNA sequences to surface-spread pachytene chromosomes of rye

Genome ◽

10.1139/g92-082 ◽

1992 ◽

Vol 35 (4) ◽

pp. 551-559 ◽

Cited By ~ 25

Author(s):

S. M. Albini ◽

T. Schwarzacher

Keyword(s):

In Situ Hybridization ◽

Synaptonemal Complex ◽

Dna Sequences ◽

Meiotic Prophase ◽

Hybridization Signal ◽

Metaphase Chromosomes ◽

Somatic Metaphase ◽

Rdna Signal ◽

Surface Spread

Surface-spread pollen mother cells at meiotic prophase from Secale cereale (rye) were used for fluorescent DNA:DNA in situ localization of two tandemly repeated DNA sequences: pTa71, a wheat rDNA clone, and pSc119.2, a cloned 120-bp repeat from rye heterochromatin. The fluorescent hybridization signal, consisting of many yellow-green dots, was closely associated with the bivalent axes, corresponding to the synaptonemal complex, and located in the surrounding chromatin. The rDNA signal was associated with one bivalent, the smallest of the seven, at a distance about 13% of the bivalent length from the telomere. This corresponded to the position of the nucleolar organizing region of silver-stained synaptonemal complexes analyzed under the electron microscope and published data for somatic metaphase chromosomes. The relative length of the axis covered with the rDNA signal is less than expected from somatic metaphases, but it corresponds more closely to the proportion of the sequences in the genome. The hybridization signal with the 120-bp repeat was located mainly at the telomeric regions of several bivalents that showed thickenings of the axis after DAPI staining, probably corresponding to somatic C-bands. These major and some minor intercalary sites agree with the distribution of the 120-bp repeat in somatic metaphase. Fluorescent in situ hybridization to plant surface-spread pachytene chromosomes, which can be obtained in large numbers, has great potential for studying meiotic prophase, high-resolution mapping of DNA sequences, and investigating the relationship of DNA sequences to the synaptonemal complex.Key words: in situ hybridization, cereals, pachytene, meiosis, synaptonemal complex, physical mapping.

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

Molecular Biology of the Cell ◽

10.1091/mbc.e12-11-0841 ◽

2013 ◽

Vol 24 (7) ◽

pp. 1053-1067 ◽

Cited By ~ 25

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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Identical megabase transgenes on mouse chromosomes 3 and 4 do not promote ectopic pairing or synapsis at meiosis

Genome ◽

10.1139/g97-799 ◽

1997 ◽

Vol 40 (5) ◽

pp. 770-773 ◽

Cited By ~ 9

Author(s):

P. B. Moens ◽

J. A. M. Heddle ◽

B. Spyropoulos ◽

H. H. Q. Heng

Keyword(s):

In Situ Hybridization ◽

Fluorescence In Situ Hybridization ◽

Synaptonemal Complex ◽

Meiotic Prophase ◽

Nuclear Volume ◽

Dna Interactions ◽

Synaptonemal Complexes ◽

Meiotic Chromosomes ◽

Ectopic Pairing

To investigate ectopic interactions at the chromatin level, we examined the meiotic organization of 1–2 mb phage λ transgenes on mouse chromosomes 3 and 4 by fluorescence in situ hybridization in combination with immunocytology of meiotic chromosomes. At early meiotic prophase, the transgenes are sufficiently dispersed in the nuclear volume to permit potential DNA–DNA interactions, but no synaptonemal complexes form between the sites of transgenes residing on different chromosomes. At later stages, when the chromatin is more condensed, the transgenes on different chromosomes are not preferentially associated as they are when they are on the same chromosome. At diplotene and metaphase I, no formations were observed that could be interpreted as reciprocal crossovers or chiasmata between the transgenes located on chromosomes 3 and 4. It appears that in normal fertile mice, a 1- to 2-mb homology is insufficient to initiate synapsis between nonhomologs, and it is concluded that homology is assessed within the broader context of the chromosome to initiate synapsis at meiotic prophase.Key words: transgenes, ectopic pairing, meiosis, synaptonemal complex, immunocytology, FISH.

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Spectral karyotyping (SKY) of mouse meiotic chromosomes

Genome ◽

10.1139/g01-018 ◽

2001 ◽

Vol 44 (2) ◽

pp. 293-298 ◽

Cited By ~ 16

Author(s):

Henry HQ Heng ◽

Guo Liu ◽

Wei Lu ◽

Steve Bremer ◽

Christine J Ye ◽

...

Keyword(s):

In Situ Hybridization ◽

Synaptonemal Complex ◽

Meiotic Prophase ◽

Spectral Karyotyping ◽

Mitotic Chromosomes ◽

Meiotic Chromosomes ◽

Y Chromosomes ◽

Behavioural Characteristics ◽

Co Detection

The spectral karyotyping procedure of in situ hybridization with chromosome-specific probes assigns a unique colour code to each of the 21 mouse mitotic chromosomes. We have adapted this procedure to meiotic prophase chromosomes, and the results show that each of the pachytene or metaphase I bivalents can be identified. This technique has the potential to recognize synaptic anomalies and chromosome-specific structural and behavioural characteristics. We confirm these potentials by the recognition of the heterologous synapsis of the X and Y chromosomes and by the variances of synaptonemal complex lengths for each of the colour-coded bivalents in eight prophase nuclei.Key words: SKY, meiosis, synaptonemal complex, multicolour, chromosome painting, spectral karyotyping, protein-SKY co-detection.

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The BRCA1-BARD1 complex associates with the synaptonemal complex and pro-crossover factors and influences RAD-51 dynamics during Caenorhabditis elegans meiosis

10.1101/280214 ◽

2018 ◽

Author(s):

Eva Janisiw ◽

Maria Rosaria Dello Stritto ◽

Verena Jantsch ◽

Nicola Silva

Keyword(s):

Dna Repair ◽

Caenorhabditis Elegans ◽

Synaptonemal Complex ◽

Meiotic Prophase ◽

Double Strand Breaks ◽

Pivotal Role ◽

Dna Double Strand Breaks ◽

Strand Breaks ◽

Homologous Chromosomes ◽

Meiotic Prophase I

AbstractDuring meiosis, the maternal and paternal homologous chromosomes must align along their entire length and recombine to achieve faithful segregation in the gametes. Meiotic recombination is accomplished through the formation of DNA double-strand breaks, a subset of which can mature into crossovers to link the parental homologous chromosomes and promote their segregation. Breast and ovarian cancer susceptibility protein BRCA1 and its heterodimeric partner BARD1 play a pivotal role in DNA repair in mitotic cells; however, their functions in gametogenesis are less well understood. Here we show that localization of BRC-1 and BRD-1 (Caenorhabditis elegans orthologues of BRCA1 and BARD1) is dynamic during meiotic prophase I; they ultimately becoming concentrated at regions surrounding the presumptive crossover sites, co-localizing with the pro-crossover factors COSA-1, MSH-5 and ZHP-3. The synaptonemal complex is essential for BRC-1 loading onto chromosomes but recombination is not. BRC-1 forms an in vivo complex with the synaptonemal complex component SYP-3 and the crossover-promoting factor MSH-5. Furthermore, BRC-1 is essential for efficient stage-specific recruitment of the RAD-51 recombinase to DNA damage sites when synapsis is impaired and upon induction of exogenous DNA double-strand breaks. Taken together, our data provide new insights into the localization and meiotic function of the BRC-1–BRD-1 complex and highlight their essential role in DNA double-strand break repair during gametogenesis.Author summarySexually reproducing species rely on meiosis to transmit their genetic information across generations. Parental chromosomes (homologues) undergo many distinctive processes in their complex journey from attachment to segregation. The physiological induction of DNA double strand breaks is crucial for promoting correct chromosome segregation: they are needed to activate the DNA repair machinery responsible for creating physical connections, or crossovers (COs), between the homologues. In turn, crossovers promote the accurate segregation of the chromosomes in daughter cells. The BRCA1–BARD1 complex has a pivotal role during DNA repair in somatic cells and is exclusively located on unaligned chromosomal regions during mammalian meiosis. We show that in Caenorhabditis elegans, BRCA1 and BARD1 localize to chromosomes at all stages of meiotic prophase I and are enriched at presumptive crossover sites. We found that BRCA1 promotes DNA loading of the repair factor RAD-51 in specific mutant backgrounds and upon exogenous damage induction. Our data provide evidence for a direct physical association between BRCA1 and pro-crossover factors (including the synaptonemal complex) and identify an important role for BRCA1 in stimulating meiotic DNA repair. Further studies are necessary to identify the substrates acted upon by BRCA1–BARD1 complex to maintain genome stability in the gametes.

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FBXO47 regulates telomere-inner nuclear envelope integration by stabilizing TRF2 during meiosis

Nucleic Acids Research ◽

10.1093/nar/gkz992 ◽

2019 ◽

Author(s):

Rong Hua ◽

Huafang Wei ◽

Chao Liu ◽

Yue Zhang ◽

Siyu Liu ◽

...

Keyword(s):

Nuclear Envelope ◽

Synaptonemal Complex ◽

Meiotic Prophase ◽

Homologous Chromosomes ◽

Prophase I ◽

Shelterin Complex ◽

Meiotic Prophase I ◽

F Box Protein ◽

Bouquet Stage

Abstract During meiosis, telomere attachment to the inner nuclear envelope is required for proper pairing of homologous chromosomes and recombination. Here, we identified F-box protein 47 (FBXO47) as a regulator of the telomeric shelterin complex that is specifically expressed during meiotic prophase I. Knockout of Fbxo47 in mice leads to infertility in males. We found that the Fbxo47 deficient spermatocytes are unable to form a complete synaptonemal complex. FBXO47 interacts with TRF1/2, and the disruption of Fbxo47 destabilizes TRF2, leading to unstable telomere attachment and slow traversing through the bouquet stage. Our findings uncover a novel mechanism of FBXO47 in telomeric shelterin subunit stabilization during meiosis.

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Ultrastructure of primary spermatocyte in fish (Tilapia: Oreochromis niloticus): The synaptonemal complex

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100143067 ◽

1986 ◽

Vol 44 ◽

pp. 288-289

Author(s):

T. Guha ◽

A. Q. Siddiqui ◽

P. F. Prentis

Keyword(s):

Fine Structure ◽

Electron Microscope ◽

Synaptonemal Complex ◽

Oreochromis Niloticus ◽

Short Communication ◽

Primary Spermatocyte ◽

Mitotic Division ◽

Meiotic Cell ◽

Electron Microscope Level ◽

Homologous Chromosomes

The Primary Spermatocytes represent a stage in spermatogenesis when the first meiotic cell division occurs. They are derived from Spermatogonium or Stem cell through mitotic division. At the zygotene phase of meiotic prophase the Synaptonemal complex appears in these cells in the space between the paired homologous chromosomes. Spermatogenesis and sperm structure in fish have been studied at the electron microscope level in a few species? However, no work has yet been reported on ultrastructure of tilapia, O. niloticus, spermatozoa and spermatogenetic process. In this short communication we are reporting the Ultrastructure of Primary Spermatocytes in tilapia, O. niloticus, and the fine structure of synaptonemal complexes seen in the spermatocyte nuclei.

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Application of biotinylated oligonucleotide probes to the detection of pituitary hormone mRNA using Northern blot analysis, in situ hybridization at the light- and electron-microscope levels

The Histochemical Journal ◽

10.1007/bf00188075 ◽

1994 ◽

Vol 26 (10) ◽

pp. 771-777 ◽

Cited By ~ 1

Author(s):

Akira Matsuno ◽

Akira Teramoto ◽

Susumu Takekoshi ◽

Hirotoshi Utsunomiya ◽

Yoshitaka Ohsugi ◽

...

Keyword(s):

In Situ Hybridization ◽

Electron Microscope ◽

Northern Blot ◽

Blot Analysis ◽

Northern Blot Analysis ◽

Pituitary Hormone ◽

Oligonucleotide Probes

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Pituitary adenoma producing growth hormone and adrenocorticotropin: a histological, immunocytochemical, electron microscopic, and in situ hybridization study

Journal of Neurosurgery ◽

10.3171/jns.1998.88.6.1111 ◽

1998 ◽

Vol 88 (6) ◽

pp. 1111-1115 ◽

Cited By ~ 27

Author(s):

Kalman Kovacs ◽

Eva Horvath ◽

Lucia Stefaneanu ◽

Juan Bilbao ◽

William Singer ◽

...

Keyword(s):

Growth Hormone ◽

In Situ Hybridization ◽

Pituitary Adenoma ◽

Immunoelectron Microscopy ◽

Secretory Granules ◽

Cell Types ◽

Content Type ◽

Separate Cell ◽

Fine Print

✓ The authors report on the morphological features of a pituitary adenoma that produced growth hormone (GH) and adrenocorticotropic hormone (ACTH). This hormone combination produced by a single adenoma is extremely rare; a review of the available literature showed that only one previous case has been published. The tumor, which was removed from a 62-year-old man with acromegaly, was studied by histological and immunocytochemical analyses, transmission electron microscopy, immunoelectron microscopy, and in situ hybridization. When the authors used light microscopy, the tumor appeared to be a bimorphous mixed pituitary adenoma composed of two separate cell types: one cell population synthesized GH and the other ACTH. The cytogenesis of pituitary adenomas that produce more than one hormone is obscure. It may be that two separate cells—one somatotroph and one corticotroph—transformed into neoplastic cells, or that the adenoma arose in a common stem cell that differentiated into two separate cell types. In this case immunoelectron microscopy conclusively demonstrated ACTH in the secretory granules of several somatotrophs. This was associated with a change in the morphological characteristics of secretory granules. Thus it is possible that the tumor was originally a somatotropic adenoma that began to produce ACTH as a result of mutations that occurred during tumor progression.

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