Meiotic chromosome segregation is critical for fertility across eukaryotes, and core meiotic processes are well conserved even between kingdoms. Nevertheless, recent work in animals has shown that at least some meiosis genes are highly diverse or strongly differentiated among populations. What drives this remains largely unknown. We previously showed that autotetraploid Arabidopsis arenosa evolved stable meiosis, likely through reduced crossover rates, and that associated with this there is strong evidence for selection in a subset of meiosis genes known to affect axis formation, synapsis, and crossover frequency. Here, we use genome-wide data to study the molecular evolution of 70 meiosis genes in a much wider sample of A. arenosa. We sample the polyploid lineage, a diploid lineage from the Carpathian Mountains, and a more distantly related diploid lineage from the adjacent, but biogeographically distinct Pannonian Basin. We find that not only did selection act on meiosis genes in the polyploid lineage but also independently on a smaller subset of meiosis genes in Pannonian diploids. Functionally related genes are targeted by selection in these distinct contexts, and in two cases, independent sweeps occurred in the same loci. The tetraploid lineage has sustained selection on more genes, has more amino acid changes in each, and these more often affect conserved or potentially functional sites. We hypothesize that Pannonian diploid and tetraploid A. arenosa experienced selection on structural proteins that mediate sister chromatid cohesion, the formation of meiotic chromosome axes, and synapsis, likely for different underlying reasons.

• Klíčová slova
• evolution, meiosis, polyploidy,
• MeSH
• Arabidopsis genetika   MeSH
• diploidie * MeSH
• meióza genetika   MeSH
• molekulární evoluce * MeSH
• rostlinné geny * MeSH
• segregace chromozomů MeSH
• tetraploidie * MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Research Support, N.I.H., Extramural MeSH

Unisexual reproduction, which generates clonal offspring, is an alternative strategy to sexual breeding and occurs even in vertebrates. A wide range of non-sexual reproductive modes have been described, and one of the least understood questions is how such pathways emerged and how they mechanistically proceed. The Amazon molly, Poecilia formosa, needs sperm from males of related species to trigger the parthenogenetic development of diploid eggs. However, the mechanism, of how the unreduced female gametes are produced, remains unclear. Cytological analyses revealed that the chromosomes of primary oocytes initiate pachytene but do not proceed to bivalent formation and meiotic crossovers. Comparing ovary transcriptomes of P. formosa and its sexual parental species revealed expression levels of meiosis-specific genes deviating from P. mexicana but not from P. latipinna. Furthermore, several meiosis genes show biased expression towards one of the two alleles from the parental genomes. We infer from our data that in the Amazon molly diploid oocytes are generated by apomixis due to a failure in the synapsis of homologous chromosomes. The fact that this failure is not reflected in the differential expression of known meiosis genes suggests the underlying molecular mechanism may be dysregulation on the protein level or misexpression of a so far unknown meiosis gene, and/or hybrid dysgenesis because of compromised interaction of proteins from diverged genomes.

• Klíčová slova
• Achiasmatic, Crossing-over, Meiosis, Oogenesis, Parthenogenesis, Recombination, Synaptonemal complex, Transcriptome,
• MeSH
• meióza MeSH
• sperma MeSH
• transkriptom MeSH
• živorodka * genetika   MeSH
• zvířata MeSH
• Check Tag
• mužské pohlaví MeSH
• ženské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Geografické názvy
• Taiwan MeSH

Chromosome segregation during female meiosis is frequently incorrect with severe consequences including termination of further development or severe disorders, such as Down syndrome. Accurate chromosome segregation requires tight control of a protease called separase, which facilitates the separation of sister chromatids by cohesin cleavage. There are several control mechanisms in place, including the binding of specific protein inhibitor securin, phosphorylation by cyclin-dependent kinase 1 (CDK1), and complex with SGO2 and MAD2 proteins. All these mechanisms restrict the activation of separase for the time when all chromosomes are properly attached to the spindle. In our study, we focused on securin and compared the expression profile of endogenous protein with exogenous securin, which is widely used to study chromosome segregation. We also compared the dynamics of securin proteolysis in meiosis I and meiosis II. Our study revealed that the expression of both endogenous and exogenous securin in oocytes is compartmentalized and that this protein accumulates on the spindle during meiosis I. We believe that this might have a direct impact on the regulation of separase activity in the vicinity of the chromosomes.

• Klíčová slova
• meiosis, mouse, oocyte, securin, separase,
• Publikační typ
• časopisecké články MeSH

Cells are equipped with a diverse network of signaling and regulatory proteins that function as cell cycle regulators and checkpoint proteins to ensure the proper progression of cell division. A key regulator of cell division is polo-like kinase 1 (PLK1), a member of the serine/threonine kinase family that plays an important role in regulating the mitotic and meiotic cell cycle. The phosphorylation of specific substrates mediated by PLK1 controls nuclear envelope breakdown (NEBD), centrosome maturation, proper spindle assembly, chromosome segregation, and cytokinesis. In mammalian oogenesis, PLK1 is essential for resuming meiosis before ovulation and for establishing the meiotic spindle. Among other potential roles, PLK1 regulates the localized translation of spindle-enriched mRNAs by phosphorylating and thereby inhibiting the translational repressor 4E-BP1, a downstream target of the mTOR (mammalian target of rapamycin) pathway. In this review, we summarize the functions of PLK1 in mitosis, meiosis, and cytokinesis and focus on the role of PLK1 in regulating mRNA translation. However, knowledge of the role of PLK1 in the regulation of meiosis remains limited.

• Klíčová slova
• PLK1, mRNA translation, meiosis, mitosis, oocytes, polo-like kinase 1, spindle,
• MeSH
• lidé MeSH
• meióza MeSH
• mitóza MeSH
• polo-like kinasa 1 MeSH
• protein-serin-threoninkinasy * metabolismus   MeSH
• proteiny buněčného cyklu * metabolismus   MeSH
• protoonkogenní proteiny metabolismus   MeSH
• Check Tag
• lidé MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• přehledy MeSH
• Názvy látek
• protein-serin-threoninkinasy * MeSH
• proteiny buněčného cyklu * MeSH
• protoonkogenní proteiny MeSH

Live imaging combined with the application of chemical inhibitors is a powerful research tool that enables researchers to precisely time the inhibition of cellular processes and study the consequences of these perturbations. This approach is usually applied to in vitro cultivated cells that are easily accessible to chemical treatments and microscopic observations. Here we describe a method for live cell imaging of Arabidopsis meiocytes embedded within floral organs combined with the application of a chemical drug at desired timepoints during meiosis. We describe a customized solution for the Zeiss Z.1 light sheet microscope, including sample preparation and data processing, and demonstrate its utility for the analysis of meiotic progression upon spindle inhibition.

• Klíčová slova
• Arabidopsis, Germline, LSFM, Light sheet fluorescence microscopy, Live imaging, Meiosis, Oryzalin, Reproduction,
• MeSH
• Arabidopsis * MeSH
• fluorescenční mikroskopie metody   MeSH
• meióza * MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Chromosomal rearrangements (e.g., fusions/fissions) have the potential to drive speciation. However, their accumulation in a population is generally viewed as unlikely, because chromosomal heterozygosity should lead to meiotic problems and aneuploid gametes. Canonical meiosis involves segregation of homologous chromosomes in meiosis I and sister chromatid segregation during meiosis II. In organisms with holocentric chromosomes, which are characterized by kinetic activity distributed along almost the entire chromosome length, this order may be inverted depending on their metaphase I orientation. Here we analyzed the evolutionary role of this intrinsic versatility of holocentric chromosomes, which is not available to monocentric ones, by studying F1 to F4 hybrids between two chromosomal races of the Wood White butterfly (Leptidea sinapis), separated by at least 24 chromosomal fusions/fissions. We found that these chromosomal rearrangements resulted in multiple meiotic multivalents, and, contrary to the theoretical prediction, the hybrids displayed relatively high reproductive fitness (42% of that of the control lines) and regular behavior of meiotic chromosomes. In the hybrids, we also discovered inverted meiosis, in which the first and critical stage of chromosome number reduction was replaced by the less risky stage of sister chromatid separation. We hypothesize that the ability to invert the order of the main meiotic events facilitates proper chromosome segregation and hence rescues fertility and viability in chromosomal hybrids, potentially promoting dynamic karyotype evolution and chromosomal speciation.

• Klíčová slova
• chromosomal evolution, chromosomal rearrangement, hybridization, inverted meiosis, speciation,
• MeSH
• chiméra * genetika   metabolismus   MeSH
• chromatidy * genetika   metabolismus   MeSH
• chromozomy hmyzu genetika   metabolismus   MeSH
• metafáze fyziologie   MeSH
• motýli * genetika   metabolismus   MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

The role of hydrogen sulfide (H2S) is addressed in Xenopuslaevis oocytes. Three enzymes involved in H2S metabolism, cystathionine β-synthase, cystathionine γ-lyase, and 3-mercaptopyruvate sulfurtransferase, were detected in prophase I and metaphase II-arrested oocytes and drove an acceleration of oocyte meiosis resumption when inhibited. Moreover, meiosis resumption is associated with a significant decrease in endogenous H2S. On another hand, a dose-dependent inhibition was obtained using the H2S donor, NaHS (1 and 5 mM). NaHS impaired translation. NaHS did not induce the dissociation of the components of the M-phase promoting factor (MPF), cyclin B and Cdk1, nor directly impacted the MPF activity. However, the M-phase entry induced by microinjection of metaphase II MPF-containing cytoplasm was diminished, suggesting upstream components of the MPF auto-amplification loop were sensitive to H2S. Superoxide dismutase and catalase hindered the effects of NaHS, and this sensitivity was partially dependent on the production of reactive oxygen species (ROS). In contrast to other species, no apoptosis was promoted. These results suggest a contribution of H2S signaling in the timing of amphibian oocytes meiosis resumption.

• Klíčová slova
• Xenopus laevis, cell cycle, hydrogen sulfide, meiosis, oocyte,
• MeSH
• apoptóza účinky léků   MeSH
• cyklin B metabolismus   MeSH
• cystathionin-beta-synthasa antagonisté a inhibitory   metabolismus   MeSH
• cystathionin-gama-lyasa antagonisté a inhibitory   metabolismus   MeSH
• cytoplazma metabolismus   MeSH
• faktor podporující zrání metabolismus   MeSH
• fosfatasy cdc25 metabolismus   MeSH
• katalasa metabolismus   MeSH
• meióza účinky léků   MeSH
• metafáze účinky léků   MeSH
• oocyty chemie   enzymologie   metabolismus   MeSH
• profáze meiózy I účinky léků   MeSH
• proteinkinasy metabolismus   MeSH
• proteiny buněčného cyklu metabolismus   MeSH
• proteiny Xenopus metabolismus   MeSH
• reaktivní formy kyslíku metabolismus   MeSH
• signální transdukce účinky léků   MeSH
• sulfan metabolismus   MeSH
• sulfidy metabolismus   farmakologie   MeSH
• sulfurtransferasy antagonisté a inhibitory   metabolismus   MeSH
• superoxiddismutasa metabolismus   MeSH
• viabilita buněk účinky léků   MeSH
• Xenopus laevis MeSH
• zvířata MeSH
• Check Tag
• ženské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• 3-mercaptopyruvate sulphurtransferase MeSH Prohlížeč
• CDC25C protein, human MeSH Prohlížeč
• CDK1 protein, Xenopus MeSH Prohlížeč
• cyklin B MeSH
• cystathionin-beta-synthasa MeSH
• cystathionin-gama-lyasa MeSH
• faktor podporující zrání MeSH
• fosfatasy cdc25 MeSH
• katalasa MeSH
• proteinkinasy MeSH
• proteiny buněčného cyklu MeSH
• proteiny Xenopus MeSH
• reaktivní formy kyslíku MeSH
• sodium bisulfide MeSH Prohlížeč
• sulfan MeSH
• sulfidy MeSH
• sulfurtransferasy MeSH
• superoxiddismutasa MeSH

The rate of chromosome segregation errors that emerge during meiosis I in the mammalian female germ line are known to increase with maternal age; however, little is known about the underlying molecular mechanism. The objective of this study was to analyze meiotic progression of mouse oocytes in relation to maternal age. Using the mouse as a model system, we analyzed the timing of nuclear envelope breakdown and the morphology of the nuclear lamina of oocytes obtained from young (2 months old) and aged females (12 months old). Oocytes obtained from older females display a significantly faster progression through meiosis I compared to the ones obtained from younger females. Furthermore, in oocytes from aged females, lamin A/C structures exhibit rapid phosphorylation and dissociation. Additionally, we also found an increased abundance of MPF components and increased translation of factors controlling translational activity in the oocytes of aged females. In conclusion, the elevated MPF activity observed in aged female oocytes affects precocious meiotic processes that can multifactorially contribute to chromosomal errors in meiosis I.

• Klíčová slova
• MPF, aging, lamin A/C, meiosis, oocyte, translation,
• MeSH
• faktor podporující zrání genetika   metabolismus   MeSH
• fosforylace MeSH
• jaderný obal metabolismus   ultrastruktura   MeSH
• meióza * MeSH
• mezotelin MeSH
• myši MeSH
• oocyty cytologie   metabolismus   MeSH
• posttranslační úpravy proteinů MeSH
• stárnutí genetika   metabolismus   MeSH
• zvířata MeSH
• Check Tag
• myši MeSH
• ženské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• faktor podporující zrání MeSH
• mezotelin MeSH
• Msln protein, mouse MeSH Prohlížeč

BACKGROUND AND AIMS: Despite their abundant odd-ploidy (2n = 5x = 35), dogroses (Rosa sect. Caninae) are capable of sexual reproduction due to their unique meiosis. During canina meiosis, two sets of chromosomes form bivalents and are transmitted by male and female gametes, whereas the remaining chromosomes form univalents and are exclusively transmitted by the egg cells. Thus, the evolution of chromosomes is expected to be driven by their behaviour during meiosis. METHODS: To gain insight into differential chromosome evolution, fluorescence in situ hybridization was conducted for mitotic and meiotic chromosomes in four dogroses (two subsections) using satellite and ribosomal DNA probes. By exploiting high-throughput sequencing data, we determined the abundance and diversity of the satellite repeats in the genus Rosa by analysing 20 pentaploid, tetraploid and diploid species in total. KEY RESULTS: A pericentromeric satellite repeat, CANR4, was found in all members of the genus Rosa, including the basal subgenera Hulthemia and Hesperhodos. The satellite was distributed across multiple chromosomes (5-20 sites per mitotic cell), and its genomic abundance was higher in pentaploid dogroses (2.3 %) than in non-dogrose species (1.3 %). In dogrose meiosis, univalent chromosomes were markedly enriched in CANR4 repeats based on both the number and the intensity of the signals compared to bivalent-forming chromosomes. Single-nucleotide polymorphisms and cluster analysis revealed high intragenomic homogeneity of the satellite in dogrose genomes. CONCLUSIONS: The CANR4 satellite arose early in the evolution of the genus Rosa. Its high content and extraordinary homogeneity in dogrose genomes is explained by its recent amplification in non-recombining chromosomes. We hypothesize that satellite DNA expansion may contribute to the divergence of univalent chromosomes in Rosa species with non-symmetrical meiosis.

• Klíčová slova
• Rosa, chromosome evolution, dogroses, genetic recombination, meiosis, polyploidy, repeatome, satellite DNA,
• MeSH
• DNA rostlinná MeSH
• genom rostlinný MeSH
• hybridizace in situ fluorescenční MeSH
• lidé MeSH
• meióza MeSH
• polyploidie MeSH
• Rosa genetika   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• DNA rostlinná MeSH

Cell division cycle (Cdc) kinase subunit (CKS) proteins bind cyclin-dependent kinases (CDKs) and play important roles in cell division control and development, though their precise molecular functions are not fully understood. Mammals express two closely related paralogs called CKS1 and CKS2, but only CKS2 is expressed in the germ line, indicating that it is solely responsible for regulating CDK functions in meiosis. Using cks2-/- knockout mice, we show that CKS2 is a crucial regulator of maturation-promoting factor (MPF; CDK1-cyclin A/B) activity in meiosis. cks2-/- oocytes display reduced and delayed MPF activity during meiotic progression, leading to defects in germinal vesicle breakdown (GVBD), anaphase-promoting complex/cyclosome (APC/C) activation, and meiotic spindle assembly. cks2-/- germ cells express significantly reduced levels of the MPF components CDK1 and cyclins A1/B1. Additionally, injection of MPF plus CKS2, but not MPF alone, restored normal GVBD in cks2-/- oocytes, demonstrating that GVBD is driven by a CKS2-dependent function of MPF. Moreover, we generated cks2cks1/cks1 knock-in mice and found that CKS1 can compensate for CKS2 in meiosis in vivo, but homozygous embryos arrested development at the 2- to 5-cell stage. Collectively, our results show that CKS2 is a crucial regulator of MPF functions in meiosis and that its paralog, CKS1, must be excluded from the germ line for proper embryonic development.

• Klíčová slova
• CKS, cyclin-dependent kinases, developmental biology, meiosis,
• MeSH
• embryonální vývoj * MeSH
• faktor podporující zrání metabolismus   MeSH
• genový knockin MeSH
• kinasy CDC2-CDC28 genetika   metabolismus   MeSH
• meióza MeSH
• mezotelin MeSH
• myši knockoutované MeSH
• myši MeSH
• oocyty cytologie   metabolismus   MeSH
• proteiny buněčného cyklu genetika   metabolismus   MeSH
• zvířata MeSH
• Check Tag
• mužské pohlaví MeSH
• myši MeSH
• ženské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Research Support, N.I.H., Extramural MeSH
• Názvy látek
• Cks1 protein, mouse MeSH Prohlížeč
• Cks2 protein, mouse MeSH Prohlížeč
• faktor podporující zrání MeSH
• kinasy CDC2-CDC28 MeSH
• mezotelin MeSH
• Msln protein, mouse MeSH Prohlížeč
• proteiny buněčného cyklu MeSH