Faithful meiotic segregation requires pairwise alignment of the homologous chromosomes and their synaptonemal complex (SC) mediated stabilization. Here, we investigate factors that promote and coordinate these events during C. elegans meiosis. We identify BRA-2 (BMP Receptor Associated family member 2) as an interactor of HIM-17, previously shown to promote double-strand break formation. We found that loss of bra-2 impairs synapsis elongation without affecting homolog recognition, chromosome movement or SC maintenance. Epistasis analyses reveal previously unrecognized activities for HIM-17 in regulating homolog pairing and SC assembly in a partially overlapping manner with BRA-2. We show that removing bra-2 or him-17 restores nuclear clustering, recruitment of PLK-2 at the nuclear periphery, and abrogation of ectopic synapsis in htp-1 mutants, suggesting intact CHK-2-mediated signaling and presence of a barrier that prevents SC polymerization in the absence of homology. Our findings shed light on the regulatory mechanisms ensuring faithful pairing and synapsis.

• MeSH
• Caenorhabditis elegans * genetika   metabolismus   cytologie   MeSH
• meióza * genetika   fyziologie   MeSH
• mutace MeSH
• párování chromozomů * genetika   MeSH
• proteiny buněčného cyklu * metabolismus   genetika   MeSH
• proteiny Caenorhabditis elegans * metabolismus   genetika   MeSH
• synaptonemální komplex metabolismus   genetika   MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• Htp-1 protein, C elegans MeSH Prohlížeč
• proteiny buněčného cyklu * MeSH
• proteiny Caenorhabditis elegans * MeSH

BACKGROUND: The synaptonemal complex (SC) is a protein axis formed along chromosomes during meiotic prophase to ensure proper pairing and crossing over. SC analysis has been widely used to study the chromosomes of mammals and less frequently of birds, reptiles, and fish. It is a promising method to investigate the evolution of fish genomes and chromosomes as a part of complex approach. SUMMARY: Compared with conventional metaphase chromosomes, pachytene chromosomes are less condensed and exhibit pairing between homologous chromosomes. These features of SCs facilitate the study of the small chromosomes that are typical in fish. Moreover, it allows the study of heteromorphisms in sex chromosomes and supernumerary chromosomes. In addition, it enables the investigation of the pairing between orthologous chromosomes in hybrids, which is crucial for uncovering the causes of hybrid sterility and asexual reproduction, such as gynogenesis or hybridogenesis. However, the application of SC analysis to fish chromosomes is limited by the associated complications. First, in most fish, meiosis does not occur during every season and life stage. Second, different SC preparation methods are optimal for different fish species. Third, commercial antibodies targeting meiotic proteins have been primarily developed against mammalian antigens, and not all of them are suitable for fish chromosomes. KEY MESSAGES: In the present review, we provide an overview of the methods for preparing fish SCs and highlight important studies using SC analysis in fish. This study will be valuable for planning and designing research that applies SC analysis to fish cytogenetics and genomics.

• Klíčová slova
• Chromosome structure, Fluorescent in situ hybridization, Hybrid sterility, Meiosis, Sex chromosomes,
• MeSH
• chromozomy genetika   MeSH
• meióza * genetika   MeSH
• molekulární evoluce MeSH
• pohlavní chromozomy genetika   MeSH
• ryby * genetika   MeSH
• synaptonemální komplex * genetika   MeSH
• zvířata MeSH
• Check Tag
• mužské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• přehledy MeSH

Mitosis and cytokinesis are fundamental processes through which somatic cells increase their numbers and allow plant growth and development. Here, we analyzed the organization and dynamics of mitotic chromosomes, nucleoli, and microtubules in living cells of barley root primary meristems using a series of newly developed stable fluorescent protein translational fusion lines and time-lapse confocal microscopy. The median duration of mitosis from prophase until the end of telophase was 65.2 and 78.2 min until the end of cytokinesis. We showed that barley chromosomes frequently start condensation before mitotic pre-prophase as defined by the organization of microtubules and maintain it even after entering into the new interphase. Furthermore, we found that the process of chromosome condensation does not finish at metaphase, but gradually continues until the end of mitosis. In summary, our study features resources for in vivo analysis of barley nuclei and chromosomes and their dynamics during mitotic cell cycle.

• Klíčová slova
• Hordeum vulgare, 3D nuclear organization, barley, chromatin, chromosomes, confocal microscopy, crops, live imaging, microtubules, mitosis,
• MeSH
• buněčné jádro MeSH
• chromozomy MeSH
• ječmen (rod) * genetika   MeSH
• mikrotubuly MeSH
• mitóza MeSH
• profáze MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Aneuploidy (abnormal chromosome number) accompanies reduced ovarian function in humans and mice, but the reasons behind this concomitance remain underexplored. Some variants in the human gene encoding histone-3-lysine-4,36-trimethyltransferase PRDM9 are associated with aneuploidy, and other variants with ovarian function reduced by premature ovarian failure (POF), but no link between POF and aneuploidy has been revealed. SHR/OlaIpcv rat females lacking PRDM9 manifest POF-a reduced follicle number, litter size, and reproductive age. Here, we explored this model to test how POF relates to oocyte euploidy. The mutant rat females displayed increased oocyte aneuploidy and embryonic death of their offspring compared to controls. Because rat PRDM9 positions meiotic DNA breaks, we investigated the repair of these breaks. Fertile control rodents carry pachytene oocytes with synapsed homologous chromosomes and repaired breaks, while sterile Prdm9-deficient mice carry pachytene-like oocytes with many persisting breaks and asynapsed chromosomes. However, most PRDM9-lacking rat oocytes displayed a few persisting breaks and non-homologous synapsis (NHS). HORMAD2 protein serves as a barrier to sister-chromatid repair and a signal for the synapsis and DNA repair checkpoints. NHS but not asynapsis was associated with HORMAD2 levels similar to the levels on rat pachytene chromosomes with homologous synapsis. NHS was accompanied by crossing-over decreased below the minimum that is essential for euploidy. We argue that the increased mutant rat aneuploidy is due to NHS, which allows some oocytes to pass meiotic checkpoints without one crossing-over per chromosomal pair, leading to segregation errors, and thereby NHS links POF to aneuploidy.

• MeSH
• aneuploidie * MeSH
• chromozomy MeSH
• histonlysin-N-methyltransferasa * genetika   metabolismus   MeSH
• krysa rodu Rattus MeSH
• meióza * genetika   MeSH
• oocyty metabolismus   MeSH
• párování chromozomů * genetika   MeSH
• potkani inbrední SHR MeSH
• zvířata MeSH
• Check Tag
• krysa rodu Rattus MeSH
• ženské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• histonlysin-N-methyltransferasa * MeSH

Generation of functional gametes is accomplished through a multilayered and finely orchestrated succession of events during meiotic progression. In the Caenorhabditis elegans germline, the HORMA-domain-containing protein HTP-3 plays pivotal roles for the establishment of chromosome axes and the efficient induction of programmed DNA double-strand breaks, both of which are crucial for crossover formation. Double-strand breaks allow for accurate chromosome segregation during the first meiotic division and therefore are an essential requirement for the production of healthy gametes. Phosphorylation-dependent regulation of HORMAD protein plays important roles in controlling meiotic chromosome behavior. Here, we document a phospho-site in HTP-3 at Serine 285 that is constitutively phosphorylated during meiotic prophase I. pHTP-3S285 localization overlaps with panHTP-3 except in nuclei undergoing physiological apoptosis, in which pHTP-3 is absent. Surprisingly, we observed that phosphorylation of HTP-3 at S285 is independent of the canonical kinases that control meiotic progression in nematodes. During meiosis, the htp-3(S285A) mutant displays accelerated RAD-51 turnover, but no other meiotic abnormalities. Altogether, these data indicate that the Ser285 phosphorylation is independent of canonical meiotic protein kinases and does not regulate HTP-3-dependent meiotic processes. We propose a model wherein phosphorylation of HTP-3 occurs through noncanonical or redundant meiotic kinases and/or is likely redundant with additional phospho-sites for function in vivo.

• Klíčová slova
• Caenorhabditis elegans meiosis, HORMA-domain proteins, HTP-3,
• MeSH
• Caenorhabditis elegans genetika   metabolismus   MeSH
• fosforylace MeSH
• meióza * MeSH
• proteiny buněčného cyklu genetika   MeSH
• proteiny Caenorhabditis elegans * metabolismus   MeSH
• segregace chromozomů MeSH
• serin metabolismus   MeSH
• synaptonemální komplex metabolismus   MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Research Support, N.I.H., Extramural MeSH
• Názvy látek
• proteiny buněčného cyklu MeSH
• proteiny Caenorhabditis elegans * MeSH
• serin MeSH

In this study we performed a genotype-phenotype association analysis of meiotic stability in 10 autotetraploid Arabidopsis lyrata and A. lyrata/A. arenosa hybrid populations collected from the Wachau region and East Austrian Forealps. The aim was to determine the effect of eight meiosis genes under extreme selection upon adaptation to whole genome duplication. Individual plants were genotyped by high-throughput sequencing of the eight meiosis genes (ASY1, ASY3, PDS5b, PRD3, REC8, SMC3, ZYP1a/b) implicated in synaptonemal complex formation and phenotyped by assessing meiotic metaphase I chromosome configurations. Our results reveal that meiotic stability varied greatly (20-100%) between individual tetraploid plants and associated with segregation of a novel ASYNAPSIS3 (ASY3) allele derived from A. lyrata. The ASY3 allele that associates with meiotic stability possesses a putative in-frame tandem duplication (TD) of a serine-rich region upstream of the coiled-coil domain that appears to have arisen at sites of DNA microhomology. The frequency of multivalents observed in plants homozygous for the ASY3 TD haplotype was significantly lower than in plants heterozygous for ASY3 TD/ND (non-duplicated) haplotypes. The chiasma distribution was significantly altered in the stable plants compared to the unstable plants with a shift from proximal and interstitial to predominantly distal locations. The number of HEI10 foci at pachytene that mark class I crossovers was significantly reduced in a plant homozygous for ASY3 TD compared to a plant heterozygous for ASY3 ND/TD. Fifty-eight alleles of the 8 meiosis genes were identified from the 10 populations analysed, demonstrating dynamic population variability at these loci. Widespread chimerism between alleles originating from A. lyrata/A. arenosa and diploid/tetraploids indicates that this group of rapidly evolving genes may provide precise adaptive control over meiotic recombination in the tetraploids, the very process that gave rise to them.

• MeSH
• alely MeSH
• Arabidopsis genetika   růst a vývoj   MeSH
• chromozomální proteiny, nehistonové genetika   MeSH
• chromozomy rostlin genetika   MeSH
• diploidie MeSH
• DNA vazebné proteiny genetika   MeSH
• meióza genetika   MeSH
• párování chromozomů genetika   MeSH
• proteiny huseníčku genetika   MeSH
• segregace chromozomů MeSH
• tetraploidie MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• ASY3 protein, Arabidopsis MeSH Prohlížeč
• chromozomální proteiny, nehistonové MeSH
• DNA vazebné proteiny MeSH
• HEI10 protein, Arabidopsis MeSH Prohlížeč
• proteiny huseníčku MeSH

Long transgenes are often used in mammalian genetics, e.g., to rescue mutations in large genes. In the course of experiments addressing the genetic basis of hybrid sterility caused by meiotic defects in mice bearing different alleles of Prdm9, we discovered that introduction of copy-number variation (CNV) via two independent insertions of long transgenes containing incomplete Prdm9 decreased testicular weight and epididymal sperm count. Transgenic animals displayed increased occurrence of seminiferous tubules with apoptotic cells at 18 days postpartum (dpp) corresponding to late meiotic prophase I, but not at 21 dpp. We hypothesized that long transgene insertions could cause asynapsis, but the immunocytochemical data revealed that the adult transgenic testes carried a similar percentage of asynaptic pachytene spermatocytes as the controls. These transgenic spermatocytes displayed less crossovers but similar numbers of unrepaired meiotic breaks. Despite slightly increased frequency of metaphase I spermatocytes with univalent chromosome(s) and reduced numbers of metaphase II spermatocytes, cytological studies did not reveal increased apoptosis in tubules containing the metaphase spermatocytes, but found an increased percentage of tubules carrying apoptotic spermatids. Sperm counts of subfertile animals inversely correlated with the transcription levels of the Psmb1 gene encoded within these two transgenes. The effect of the transgenes was dependent on sex and genetic background. Our results imply that the fertility of transgenic hybrid animals is not compromised by the impaired meiotic synapsis of homologous chromosomes, but can be negatively influenced by the increased expression of the introduced genes.

• Klíčová slova
• Fertility, Interspecific hybrid, Proteasome, Spermatogenesis, Transgene,
• MeSH
• apoptóza genetika   MeSH
• dvouřetězcové zlomy DNA MeSH
• fertilita genetika   MeSH
• genetické pozadí MeSH
• kontrolní body buněčného cyklu genetika   MeSH
• myši MeSH
• pachytenní stadium genetika   MeSH
• počet spermií MeSH
• spermatocyty metabolismus   MeSH
• testis anatomie a histologie   metabolismus   MeSH
• transgeny * MeSH
• variabilita počtu kopií segmentů DNA * MeSH
• velikost orgánu MeSH
• zvířata MeSH
• Check Tag
• mužské pohlaví MeSH
• myši MeSH
• ženské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

During meiosis, homologous chromosomes undergo a dramatic movement in order to correctly align. This is a critical meiotic event but the molecular properties of this 'chromosomal dance' still remainunclear. We identified DEB-1 - an orthologue of mammalian vinculin - as a new component of the mechanistic modules responsible for attaching the chromosomes to the nuclear envelope as apart of the LINC complex. In early meiotic nuclei of C. elegans, DEB-1 is localized to the nuclear periphery and alongside the synaptonemal complex of paired homologues. Upon DEB-1 depletion, chromosomes attached to SUN-1 foci remain highly motile until late pachytene. Although the initiation of homologue pairing started normally, irregularities in the formation of the synaptonemal complex occur, and these results in meiotic defects such as increased number of univalents at diakinesis and high embryonic lethality. Our data identify DEB-1 as a new player regulating chromosome dynamics and pairing during meiotic prophase I.

• Klíčová slova
• DEB-1, LINC complex, chromosome pairing, prophase I, vinculin,
• MeSH
• Caenorhabditis elegans genetika   MeSH
• chromozomy genetika   MeSH
• meióza genetika   MeSH
• párování chromozomů genetika   MeSH
• vinkulin genetika   MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• vinkulin MeSH

Chromosome pairing in meiosis usually starts in the vicinity of the telomere attachment to the nuclear membrane and congregation of telomeres in the leptotene bouquet is believed responsible for bringing homologue pairs together. In a heterozygote for an inversion of a rye (Secale cereale L.) chromosome arm in wheat, a distal segment of the normal homologue is capable of chiasmate pairing with its counterpart in the inverted arm, located near the centromere. Using 3D imaging confocal microscopy, we observed that some telomeres failed to be incorporated into the bouquet and occupied various positions throughout the entire volume of the nucleus, including the centromere pole. Rye telomeres appeared ca. 21 times more likely to fail to be included in the telomere bouquet than wheat telomeres. The frequency of the out-of-bouquet rye telomere position in leptotene was virtually identical to the frequency of telomeres deviating from Rabl's orientation in the nuclei of somatic cells, and was similar to the frequency of synapsis of the normal and inverted chromosome arms, but lower than the MI pairing frequency of segments of these two arms normally positioned across the volume of the nucleus. Out-of-position placement of the rye telomeres may be responsible for reduced MI pairing of rye chromosomes in hybrids with wheat and their disproportionate contribution to aneuploidy, but appears responsible for initiating chiasmate pairing of distantly positioned segments of homology in an inversion heterozygote.

• Klíčová slova
• 3D FISH, Centromere, Leptotene bouquet, Pairing initiation, Telomere,
• MeSH
• buněčné jádro genetika   ultrastruktura   MeSH
• centromera chemie   ultrastruktura   MeSH
• chiméra genetika   MeSH
• chromozomální inverze * MeSH
• chromozomy rostlin chemie   ultrastruktura   MeSH
• druhová specificita MeSH
• heterozygot MeSH
• hybridizace in situ fluorescenční MeSH
• konfokální mikroskopie MeSH
• párování chromozomů MeSH
• počítačové zpracování obrazu statistika a číselné údaje   MeSH
• profáze meiózy I * MeSH
• pšenice genetika   ultrastruktura   MeSH
• rostlinné buňky metabolismus   ultrastruktura   MeSH
• telomery chemie   ultrastruktura   MeSH
• žito genetika   ultrastruktura   MeSH
• zobrazování trojrozměrné metody   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Research Support, U.S. Gov't, Non-P.H.S. MeSH

PR domain containing 9 (Prdm9) is specifying hotspots of meiotic recombination but in hybrids between two mouse subspecies Prdm9 controls failure of meiotic chromosome synapsis and hybrid male sterility. We have previously reported that Prdm9-controlled asynapsis and meiotic arrest are conditioned by the inter-subspecific heterozygosity of the hybrid genome and we presumed that the insufficient number of properly repaired PRDM9-dependent DNA double-strand breaks (DSBs) causes asynapsis of chromosomes and meiotic arrest (Gregorova et al., 2018). We now extend the evidence for the lack of properly processed DSBs by improving meiotic chromosome synapsis with exogenous DSBs. A single injection of chemotherapeutic drug cisplatin increased frequency of RPA and DMC1 foci at the zygotene stage of sterile hybrids, enhanced homolog recognition and increased the proportion of spermatocytes with fully synapsed homologs at pachytene. The results bring a new evidence for a DSB-dependent mechanism of synapsis failure and infertility of intersubspecific hybrids.

• Klíčová slova
• DNA double-strand breaks, Prdm9, chromosomes, gene expression, genetics, genomics, hybrid sterility, meiosis, mouse,
• MeSH
• cisplatina toxicita   MeSH
• dvouřetězcové zlomy DNA účinky léků   MeSH
• histonlysin-N-methyltransferasa genetika   metabolismus   MeSH
• hybridizace genetická MeSH
• meióza účinky léků   genetika   MeSH
• mužská infertilita genetika   MeSH
• myši inbrední C57BL MeSH
• oprava DNA MeSH
• párování chromozomů účinky léků   genetika   MeSH
• protinádorové látky toxicita   MeSH
• zvířata MeSH
• Check Tag
• mužské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• cisplatina MeSH
• histonlysin-N-methyltransferasa MeSH
• prdm9 protein, mouse MeSH Prohlížeč
• protinádorové látky MeSH