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1.
J Cell Biol ; 222(1)2023 Jan 02.
Artigo em Inglês | MEDLINE | ID: mdl-36355348

RESUMO

Mechanisms that safeguard mitochondrial DNA (mtDNA) limit the accumulation of mutations linked to mitochondrial and age-related diseases. Yet, pathways that repair double-strand breaks (DSBs) in animal mitochondria are poorly understood. By performing a candidate screen for mtDNA repair proteins, we identify that REC-an MCM helicase that drives meiotic recombination in the nucleus-also localizes to mitochondria in Drosophila. We show that REC repairs mtDNA DSBs by homologous recombination in somatic and germline tissues. Moreover, REC prevents age-associated mtDNA mutations. We further show that MCM8, the human ortholog of REC, also localizes to mitochondria and limits the accumulation of mtDNA mutations. This study provides mechanistic insight into animal mtDNA recombination and demonstrates its importance in safeguarding mtDNA during ageing and evolution.


Assuntos
Reparo do DNA , DNA Mitocondrial , Proteínas de Drosophila , Animais , Humanos , Reparo do DNA/genética , DNA Mitocondrial/genética , Drosophila/genética , Proteínas de Drosophila/genética , Recombinação Homóloga , Meiose , Mitocôndrias/genética
2.
Gen Comp Endocrinol ; 330: 114148, 2023 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-36272447

RESUMO

BACKGROUND: While many testis-enriched genes have been identified as important regulators of the spermatogenic process, the specific roles played by several of these genes and their functional importance has yet to be fully clarified. METHODS: We employed a CRISPR/Cas9 approach to introduce a 5 bp in-frame deletion within the Spdye4a gene (Exon 2) of C57BL/6 mice (Spdye4a-/-). Fertility and sperm counts were evaluated. Testes tissues and cell suspensions were analyzed via histological and immunofluorescence staining. mRNA and protein levels of candidate genes were assessed through qPCR and Western blotting. In vitro fertilization was used to assess the ability of sperm cells to bind to egg cells. RESULTS: Spdye4a-/- mice did not exhibit any reduction in fertility, and exhibited comparable sperm counts, morphology and motility to those of wildtype littermates. Functionally, Spdye4a-/- sperm exhibited normal sperm-egg binding activity in vitro. Furthermore, the testes of Spdye4a-/- mice exhibited a full range of germ cells from spermatogonia to mature spermatozoa. No differences in the progression of meiotic prophase I were observed when comparing Spdye4a-/- and wildtype mice, indicating that the loss of Spdye4a had no adverse effect on spermatogenesis. DISCUSSION: Spdye4a is dispensable in the context of mice fertility and spermatogenesis. This study will prevent other laboratories from expending repeated efforts to generate similar knockout mice.


Assuntos
Meiose , Testículo , Masculino , Camundongos , Animais , Testículo/metabolismo , Camundongos Endogâmicos C57BL , Sêmen , Espermatogênese/genética , Espermatozoides/metabolismo , Fertilidade/genética , Espermatogônias , Camundongos Knockout
3.
Methods Mol Biol ; 2603: 19-29, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-36370267

RESUMO

Stable isotope labeling by amino acids in cell culture (SILAC) provides a powerful tool to quantify proteins and posttranslational modifications. Here we describe how to apply SILAC for protein identification and quantification in synchronous meiotic cultures induced by inactivation of the Pat1 kinase in the fission yeast Schizosaccharomyces pombe.


Assuntos
Proteínas de Schizosaccharomyces pombe , Schizosaccharomyces , Schizosaccharomyces/metabolismo , Proteômica , Meiose , Proteínas/metabolismo , Proteínas de Schizosaccharomyces pombe/genética , Proteínas de Schizosaccharomyces pombe/metabolismo
4.
PLoS Genet ; 18(11): e1010282, 2022 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-36342909

RESUMO

Female reproductive aging is associated with decreased oocyte quality and fertility. The nematode Caenorhabditis elegans is a powerful system for understanding the biology of aging and exhibits age-related reproductive defects that are analogous to those observed in many mammals, including dysregulation of DNA repair. C. elegans germline function is influenced simultaneously by both reproductive aging and signals triggered by limited supplies of sperm, which are depleted over chronological time. To delineate the causes of DNA repair defects in aged C. elegans germlines, we assessed both DNA double strand break (DSB) induction and repair during meiotic prophase I progression in aged germlines which were depleted of self-sperm, mated, or never exposed to sperm. We find that germline DSB induction is dramatically reduced only in hermaphrodites which have exhausted their endogenous sperm, suggesting that a signal due specifically to sperm depletion downregulates DSB formation. We also find that DSB repair is delayed in aged germlines regardless of whether hermaphrodites had either a reduction in sperm supply or an inability to endogenously produce sperm. These results demonstrate that in contrast to DSB induction, DSB repair defects are a feature of C. elegans reproductive aging independent of sperm presence. Finally, we demonstrate that the E2 ubiquitin-conjugating enzyme variant UEV-2 is required for efficient DSB repair specifically in young germlines, implicating UEV-2 in the regulation of DNA repair during reproductive aging. In summary, our study demonstrates that DNA repair defects are a feature of C. elegans reproductive aging and uncovers parallel mechanisms regulating efficient DSB formation in the germline.


Assuntos
Proteínas de Caenorhabditis elegans , Caenorhabditis elegans , Animais , Masculino , Feminino , Caenorhabditis elegans/genética , Proteínas de Caenorhabditis elegans/genética , Meiose , Quebras de DNA de Cadeia Dupla , Sêmen , Células Germinativas , Reparo do DNA/genética , Espermatozoides , Envelhecimento/genética , Mamíferos
5.
Nat Commun ; 13(1): 7048, 2022 Nov 17.
Artigo em Inglês | MEDLINE | ID: mdl-36396648

RESUMO

Meiosis requires the formation of programmed DNA double strand breaks (DSBs), essential for fertility and for generating genetic diversity. DSBs are induced by the catalytic activity of the TOPOVIL complex formed by SPO11 and TOPOVIBL. To ensure genomic integrity, DNA cleavage activity is tightly regulated, and several accessory factors (REC114, MEI4, IHO1, and MEI1) are needed for DSB formation in mice. How and when these proteins act is not understood. Here, we show that REC114 is a direct partner of TOPOVIBL, and identify their conserved interacting domains by structural analysis. We then analyse the role of this interaction by monitoring meiotic DSBs in female and male mice carrying point mutations in TOPOVIBL that decrease or disrupt its binding to REC114. In these mutants, DSB activity is strongly reduced genome-wide in oocytes, and only in sub-telomeric regions in spermatocytes. In addition, in mutant spermatocytes, DSB activity is delayed in autosomes. These results suggest that REC114 is a key member of the TOPOVIL catalytic complex, and that the REC114/TOPOVIBL interaction ensures the efficiency and timing of DSB activity.


Assuntos
Quebras de DNA de Cadeia Dupla , Meiose , Masculino , Feminino , Camundongos , Animais , Meiose/genética , Cromossomos , Espermatócitos , DNA
6.
Cells ; 11(21)2022 Oct 27.
Artigo em Inglês | MEDLINE | ID: mdl-36359795

RESUMO

The key to gametogenesis is the proper execution of a specialized form of cell division named meiosis. Prior to the meiotic divisions, the recombination of maternal and paternal chromosomes creates new genetic combinations necessary for fitness and adaptation to an ever-changing environment. Two rounds of chromosome segregation -meiosis I and II- have to take place without intermediate S-phase and lead to the creation of haploid gametes harboring only half of the genetic material. Importantly, the segregation patterns of the two divisions are fundamentally different and require adaptation of the mitotic cell cycle machinery to the specificities of meiosis. Separase, the enzyme that cleaves Rec8, a subunit of the cohesin complex constituting the physical connection between sister chromatids, has to be activated twice: once in meiosis I and immediately afterwards, in meiosis II. Rec8 is cleaved on chromosome arms in meiosis I and in the centromere region in meiosis II. This step-wise cohesin removal is essential to generate gametes of the correct ploidy and thus, embryo viability. Hence, separase control and Rec8 cleavage must be perfectly controlled in time and space. Focusing on mammalian oocytes, this review lays out what we know and what we still ignore about this fascinating mechanism.


Assuntos
Meiose , Oócitos , Animais , Separase/metabolismo , Oócitos/metabolismo , Centrômero , Mamíferos
7.
Elife ; 112022 11 10.
Artigo em Inglês | MEDLINE | ID: mdl-36355038

RESUMO

The dichotomy that separates prokaryotic from eukaryotic cells runs deep. The transition from pro- to eukaryote evolution is poorly understood due to a lack of reliable intermediate forms and definitions regarding the nature of the first host that could no longer be considered a prokaryote, the first eukaryotic common ancestor, FECA. The last eukaryotic common ancestor, LECA, was a complex cell that united all traits characterising eukaryotic biology including a mitochondrion. The role of the endosymbiotic organelle in this radical transition towards complex life forms is, however, sometimes questioned. In particular the discovery of the asgard archaea has stimulated discussions regarding the pre-endosymbiotic complexity of FECA. Here we review differences and similarities among models that view eukaryotic traits as isolated coincidental events in asgard archaeal evolution or, on the contrary, as a result of and in response to endosymbiosis. Inspecting eukaryotic traits from the perspective of the endosymbiont uncovers that eukaryotic cell biology can be explained as having evolved as a solution to housing a semi-autonomous organelle and why the addition of another endosymbiont, the plastid, added no extra compartments. Mitochondria provided the selective pressures for the origin (and continued maintenance) of eukaryotic cell complexity. Moreover, they also provided the energetic benefit throughout eukaryogenesis for evolving thousands of gene families unique to eukaryotes. Hence, a synthesis of the current data lets us conclude that traits such as the Golgi apparatus, the nucleus, autophagosomes, and meiosis and sex evolved as a response to the selective pressures an endosymbiont imposes.


Assuntos
Células Eucarióticas , Simbiose , Células Eucarióticas/fisiologia , Simbiose/genética , Evolução Biológica , Eucariotos/genética , Archaea/genética , Núcleo Celular , Meiose , Biologia , Filogenia
8.
Elife ; 112022 11 10.
Artigo em Inglês | MEDLINE | ID: mdl-36355419

RESUMO

Alternative splicing expands the transcriptome and proteome complexity and plays essential roles in tissue development and human diseases. However, how alternative splicing regulates spermatogenesis remains largely unknown. Here, using a germ cell-specific knockout mouse model, we demonstrated that the splicing factor Srsf10 is essential for spermatogenesis and male fertility. In the absence of SRSF10, spermatogonial stem cells can be formed, but the expansion of Promyelocytic Leukemia Zinc Finger (PLZF)-positive undifferentiated progenitors was impaired, followed by the failure of spermatogonia differentiation (marked by KIT expression) and meiosis initiation. This was further evidenced by the decreased expression of progenitor cell markers in bulk RNA-seq, and much less progenitor and differentiating spermatogonia in single-cell RNA-seq data. Notably, SRSF10 directly binds thousands of genes in isolated THY+ spermatogonia, and Srsf10 depletion disturbed the alternative splicing of genes that are preferentially associated with germ cell development, cell cycle, and chromosome segregation, including Nasp, Bclaf1, Rif1, Dazl, Kit, Ret, and Sycp1. These data suggest that SRSF10 is critical for the expansion of undifferentiated progenitors by regulating alternative splicing, expanding our understanding of the mechanism underlying spermatogenesis.


Assuntos
Processamento Alternativo , Espermatogônias , Camundongos , Animais , Masculino , Humanos , Espermatogênese/genética , Diferenciação Celular/genética , Meiose , Camundongos Knockout , Fatores de Processamento de Serina-Arginina/genética , Fatores de Processamento de Serina-Arginina/metabolismo , Proteínas Repressoras/metabolismo , Proteínas de Ciclo Celular/metabolismo
9.
Cells ; 11(22)2022 Nov 21.
Artigo em Inglês | MEDLINE | ID: mdl-36429134

RESUMO

Meiosis is a highly conserved specialized cell division process that generates haploid gametes. Many of its events are associated with dynamically regulated chromosomal structures and chromatin remodeling, which are mainly modulated by histone modifications. Histone H1 is a linker histone essential for packing the nucleosome into higher-order structures, and H1FOO (H1 histone family, member O, oocyte-specific) is a H1 variant whose expression pattern is restricted to growing oocytes and zygotes. To further explore the function of H1FOO, we generated mice lacking the H1foo gene by the CRISPR/Cas9 technique. Herein, we combine mouse genetics and cellular studies to show that H1foo-null mutants have no overt phenotype, with both males and females being fertile and presenting no gross defects in meiosis progression nor in synapsis dynamics. Accordingly, the histological sections show a normal development of gametes in both male and female mice. Considering the important role of oocyte constituents in enhancing mammalian somatic cell reprogramming, we analyzed iPSCs generation in H1foo mutant MEFs and observed no differences in the absence of H1FOO. Taken all together, in this work we present the first in vivo evidence of H1FOO dispensability for mouse fertility, clarifying the debate in the field surrounding its essentiality in meiosis.


Assuntos
Histonas , Oogênese , Feminino , Masculino , Camundongos , Animais , Oócitos , Fertilidade , Meiose , Mamíferos
10.
STAR Protoc ; 3(4): 101797, 2022 12 16.
Artigo em Inglês | MEDLINE | ID: mdl-36325582

RESUMO

Simple genetic screens in budding yeast have identified many conserved meiotic regulators. However, the identification of genes involved in specific steps of meiosis may require a more complex genetic screen that allows visualization of meiosis. Here, we describe a high-throughput protocol using fluorescence microscopy to systematically screen an overexpression library to identify genes involved in meiotic commitment. We also explain how this protocol can be adapted for identifying proteins that function at different stages of meiosis. For complete details on the use and execution of this protocol, please refer to Gavade et al. (2022).


Assuntos
Proteínas de Saccharomyces cerevisiae , Saccharomyces cerevisiae , Saccharomyces cerevisiae/genética , Proteínas de Saccharomyces cerevisiae/genética , Meiose/genética , Microscopia de Fluorescência , Testes Genéticos
11.
Cells ; 11(22)2022 Nov 11.
Artigo em Inglês | MEDLINE | ID: mdl-36428993

RESUMO

Aneuploidy is a hallmark of cancer and a major cause of miscarriages in humans. It is caused by chromosome segregation errors during cell divisions. Evidence is mounting that the probability of specific chromosomes undergoing a segregation error is non-random. In other words, some chromosomes have a higher chance of contributing to aneuploid karyotypes than others. This could have important implications for the origins of recurrent aneuploidy patterns in cancer and developing embryos. Here, we review recent progress in understanding the prevalence and causes of non-random chromosome segregation errors in mammalian mitosis and meiosis. We evaluate its potential impact on cancer and human reproduction and discuss possible research avenues.


Assuntos
Meiose , Mitose , Animais , Humanos , Meiose/genética , Mitose/genética , Cromossomos , Segregação de Cromossomos/genética , Aneuploidia , Mamíferos/genética
12.
Nat Commun ; 13(1): 7212, 2022 Nov 28.
Artigo em Inglês | MEDLINE | ID: mdl-36443288

RESUMO

Meiotic sex chromosome inactivation (MSCI) is an essential process in the male germline. While genetic experiments have established that the DNA damage response (DDR) pathway directs MSCI, due to limitations to the experimental systems available, mechanisms underlying MSCI remain largely unknown. Here we establish a system to study MSCI ex vivo, based on a short-term culture method, and demonstrate that active DDR signaling is required both to initiate and maintain MSCI via a dynamic and reversible process. DDR-directed MSCI follows two layers of modifications: active DDR-dependent reversible processes and irreversible histone post-translational modifications. Further, the DDR initiates MSCI independent of the downstream repressive histone mark H3K9 trimethylation (H3K9me3), thereby demonstrating that active DDR signaling is the primary mechanism of silencing in MSCI. By unveiling the dynamic nature of MSCI, and its governance by active DDR signals, our study highlights the sex chromosomes as an active signaling hub in meiosis.


Assuntos
Epigênese Genética , Cromossomos Sexuais , Cromossomos Sexuais/genética , Transdução de Sinais , Meiose/genética , Dano ao DNA
13.
Curr Biol ; 32(21): R1235-R1237, 2022 Nov 07.
Artigo em Inglês | MEDLINE | ID: mdl-36347233

RESUMO

A meiotic-specific structure, the synaptonemal complex, regulates meiotic recombination, but the 'language' used for this regulation has yet to be fully decoded. A new study identifies a novel phosphorylation site on the synaptonemal complex that regulates DNA repair pathway choice, revealing a new corner of the 'Rosetta Stone' for meiosis.


Assuntos
Recombinação Genética , Complexo Sinaptonêmico , Meiose
14.
Proc Natl Acad Sci U S A ; 119(47): e2207660119, 2022 Nov 22.
Artigo em Inglês | MEDLINE | ID: mdl-36375065

RESUMO

In the early stages of meiosis, maternal and paternal chromosomes pair with their homologous partner and recombine to ensure exchange of genetic information and proper segregation. These events can vary drastically between species and between males and females of the same species. In Drosophila, in contrast to females, males do not form synaptonemal complexes (SCs), do not recombine, and have no crossing over; yet, males are able to segregate their chromosomes properly. Here, we investigated the early steps of homolog pairing in Drosophila males. We found that homolog centromeres are not paired in germline stem cells (GSCs) and become paired in the mitotic region before meiotic entry, similarly to females. Surprisingly, male germline cells express SC proteins, which localize to centromeres and promote pairing. We further found that the SUN/KASH (LINC) complex and microtubules are required for homolog pairing as in females. Chromosome movements in males, however, are much slower than in females and we demonstrate that this slow dynamic is compensated in males by having longer cell cycles. In agreement, slowing down cell cycles was sufficient to rescue pairing-defective mutants in female meiosis. Our results demonstrate that although meiosis differs significantly between males and females, sex-specific cell cycle kinetics integrate similar molecular mechanisms to achieve proper centromere pairing.


Assuntos
Pareamento Cromossômico , Drosophila , Animais , Masculino , Feminino , Pareamento Cromossômico/genética , Drosophila/genética , Complexo Sinaptonêmico , Centrômero/genética , Meiose/genética , Cromossomos , Segregação de Cromossomos/genética
15.
Environ Health Perspect ; 130(11): 117007, 2022 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-36367780

RESUMO

BACKGROUND: Egg development has unique features that render it vulnerable to environmental perturbation. The herbicide atrazine is an endocrine disruptor shown to have detrimental effects on reproduction across several vertebrate species. OBJECTIVES: This study was designed to determine whether exposure to low levels of atrazine impairs meiosis in female mammals, using a mouse model; in particular, the study's researchers sought to determine whether and how the fidelity of oocyte chromosome segregation may be affected and whether aging-related aneuploidy is exacerbated. METHODS: Female C57BL/6J mice were exposed to two levels of atrazine in drinking water: The higher level equaled aqueous saturation, and the lower level corresponded to detected environmental contamination. To model developmental exposure, atrazine was ingested by pregnant females at 0.5 d post coitum and continued until pups were weaned at 21 d postpartum. For adult exposure, 2-month-old females ingested atrazine for 3 months. Following exposure, various indicators of oocyte development and quality were determined, including: a) chromosome synapsis and crossing over in fetal oocytes using immunofluorescence staining of prophase-I chromosome preparations; b) sizes of follicle pools in sectioned ovaries; c) efficiencies of in vitro fertilization and early embryogenesis; d) chromosome alignment and segregation in cultured oocytes; e) chromosomal errors in metaphase-I and -II (MI and MII) preparations; and f) sister-chromatid cohesion via immunofluorescence intensity of cohesin subunit REC8 on MI-chromosome preparations, and measurement of interkinetochore distances in MII preparations. RESULTS: Mice exposed to atrazine during development showed slightly higher levels of defects in chromosome synapsis, but sizes of initial follicle pools were indistinguishable from controls. However, although more eggs were ovulated, oocyte quality was lower. At the chromosome level, frequencies of spindle misalignment and numerical and structural abnormalities were greater at both meiotic divisions. In vitro fertilization was less efficient, and there were more apoptotic cells in blastocysts derived from eggs of atrazine-exposed females. Similar levels of chromosomal defects were seen in oocytes following both developmental and adult exposure regimens, suggesting quiescent primordial follicles may be a consequential target of atrazine. An important finding was that defects were observed long after exposure was terminated. Moreover, chromosomally abnormal eggs were very frequent in older mice, implying that atrazine exposure during development exacerbates effects of maternal aging on oocyte quality. Indeed, analogous to the effects of maternal age, weaker cohesion between sister chromatids was observed in oocytes from atrazine-exposed animals. CONCLUSION: Low-level atrazine exposure caused persistent changes to the female mammalian germline in mice, with potential consequences for reproductive lifespan and congenital disease. https://doi.org/10.1289/EHP11343.


Assuntos
Atrazina , Animais , Camundongos , Feminino , Atrazina/toxicidade , Atrazina/análise , Camundongos Endogâmicos C57BL , Meiose , Oócitos/química , Aneuploidia , Mamíferos
16.
Reprod Biol Endocrinol ; 20(1): 148, 2022 Oct 10.
Artigo em Inglês | MEDLINE | ID: mdl-36217168

RESUMO

BACKGROUND: Encapsulation of follicles within a biomatrix is one approach to maintaining 3-D follicle architecture during culture. Hyaluronan is one component of the natural extracellular matrix (ECM) that provides support to cells in vivo. This report describes the application of a novel tyramine-linked hyaluronan for 3-D in vitro follicle culture and the production of developmentally competent metaphase II oocytes. MATERIALS AND METHODS: Enzymatically isolated mouse preantral follicles or follicle clusters (FL-C) from fresh or vitrified ovaries were encapsulated in 3 mg/ml of hyaluronan gel (HA). Follicle growth, antrum formation and meiotic maturation to metaphase II oocytes was monitored. Chromatin staining was used to assess GV oocyte progression towards meiotic competence. Functional competence of in vitro matured (IVM) oocytes was evaluated by in vitro fertilization and ability to develop to blastocyst. Modifying the HA gel by inclusion of laminin (HA-LM), mouse sarcoma extracellular matrix (Matrigel;HA-MG) or placental extracellular matrix (HA-PM) was also tested to see if this might further enhance IVM outcomes. RESULTS: A total of 402 preantral follicles were cultured in HA gel. After hCG trigger, 314 oocyte-cumulus complexes ovulated from the embedded follicles. Meiotic maturation rate to the metaphase II stage was 73% (228/314). After insemination 83% (188/228) of IVM oocytes fertilized with a subsequent blastulation rate of 46% (87/188). A pilot transfer study with 3 recipient mice resulted in the birth of a single pup. HA gel supported individually isolated follicles as well ovarian tissue fragments containing clusters of 6-8 preantral follicles. Meiotic maturation was lower with FL-clusters from vitrified versus fresh ovaries (34% and 55%, respectively; p < 0.007). Modification of the HA gel with ECMs or laminin affected antrum formation and follicle retention. Maturation rates to the metaphase II stage were however not significantly different: 74% for HA gel alone as compared to HA-LM (67%), HA-MG (56%) and HA-PM (58%). CONCLUSION: Hyaluronan gel is an effective and versatile extracellular matrix based biomaterial for 3-D culture of ovarian follicles. This culture model allowed ovulation of functionally competent metaphase II oocytes, capable of fertilization, genomic activation and blastulation. Future testing with human follicles that require longer in vitro culture times should be considered.


Assuntos
Ácido Hialurônico , Laminina , Animais , Materiais Biocompatíveis , Cromatina , Feminino , Fertilização In Vitro , Humanos , Ácido Hialurônico/farmacologia , Meiose , Camundongos , Oócitos , Folículo Ovariano , Placenta , Gravidez , Tiramina
17.
Nat Commun ; 13(1): 5999, 2022 Oct 12.
Artigo em Inglês | MEDLINE | ID: mdl-36224180

RESUMO

Meiotic crossovers are limited in number and are prevented from occurring close to each other by crossover interference. In many species, crossover number is subject to sexual dimorphism, and a lower crossover number is associated with shorter chromosome axes lengths. How this patterning is imposed remains poorly understood. Here, we show that overexpression of the Arabidopsis pro-crossover protein HEI10 increases crossovers but maintains some interference and sexual dimorphism. Disrupting the synaptonemal complex by mutating ZYP1 also leads to an increase in crossovers but, in contrast, abolishes interference and disrupts the link between chromosome axis length and crossovers. Crucially, combining HEI10 overexpression and zyp1 mutation leads to a massive and unprecedented increase in crossovers. These observations support and can be predicted by, a recently proposed model in which HEI10 diffusion along the synaptonemal complex drives a coarsening process leading to well-spaced crossover-promoting foci, providing a mechanism for crossover patterning.


Assuntos
Proteínas de Arabidopsis , Arabidopsis , Arabidopsis/genética , Proteínas de Arabidopsis/genética , Proteínas Cromossômicas não Histona/genética , Troca Genética , Meiose , Complexo Sinaptonêmico
18.
Elife ; 112022 10 13.
Artigo em Inglês | MEDLINE | ID: mdl-36227631

RESUMO

Meiotic drivers are selfish elements that bias their own transmission into more than half of the viable progeny produced by a driver+/driver- heterozygote. Meiotic drivers are thought to exist for relatively short evolutionary timespans because a driver gene or gene family is often found in a single species or in a group of very closely related species. Additionally, drivers are generally considered doomed to extinction when they spread to fixation or when suppressors arise. In this study, we examine the evolutionary history of the wtf meiotic drivers first discovered in the fission yeast Schizosaccharomyces pombe. We identify homologous genes in three other fission yeast species, S. octosporus, S. osmophilus, and S. cryophilus, which are estimated to have diverged over 100 million years ago from the S. pombe lineage. Synteny evidence supports that wtf genes were present in the common ancestor of these four species. Moreover, the ancestral genes were likely drivers as wtf genes in S. octosporus cause meiotic drive. Our findings indicate that meiotic drive systems can be maintained for long evolutionary timespans.


Assuntos
Schizosaccharomyces , Meiose/genética , Schizosaccharomyces/genética
19.
BMC Genomics ; 23(1): 702, 2022 Oct 12.
Artigo em Inglês | MEDLINE | ID: mdl-36224518

RESUMO

BACKGROUND: Cellular events during meiosis can differ between inbred lines in maize. Substantial differences in the average numbers of chiasmata and double-strand breaks (DSBs) per meiotic cell have been documented among diverse inbred lines of maize: CML228, a tropical maize inbred line, B73 and Mo17, temperate maize lines. To determine if gene expression might explain these observed differences, an RNA-Seq experiment was performed on CML228 male meiocytes which was compared to B73 and Mo17 male meiocytes, where plants were grown in the same controlled environment. RESULTS: We found that a few DSB-repair/meiotic genes which promote class I crossovers (COs) and the Zyp1 gene which limits newly formed class I COs were up-regulated, whereas Mus81 homolog 2 which promotes class II COs was down-regulated in CML228. Although we did not find enriched gene ontology (GO) categories directly related to meiosis, we found that GO categories in membrane, localization, proteolysis, energy processes were up-regulated in CML228, while chromatin remodeling, epigenetic regulation, and cell cycle related processes including meiosis related cell cycle processes were down-regulated in CML228. The degree of similarity in expression patterns between the three maize lines reflect their genetic relatedness: B73 and Mo17 had similar meiotic expressions and CML228 had a more distinct expression profile. CONCLUSIONS: We found that meiotic related genes were mostly conserved among the three maize inbreds except for a few DSB-repair/meiotic genes. The findings that the molecular players in limiting class I CO formation (once CO assurance is achieved) were up-regulated and those involved in promoting class II CO formation were down-regulated in CML228 agree with the lower chiasmata number observed in CML228 previously. In addition, epigenetics such as chromatin remodeling and histone modification might play a role. Transport and energy-related processes was up-regulated and Cyclin13 was down-regulated in CML228. The direction of gene expression of these processes agree with that previously found in meiotic tissues compared with vegetative tissues. In summary, we used different natural maize inbred lines from different climatic conditions and have shown their differences in expression landscape in male meiocytes.


Assuntos
Quebras de DNA de Cadeia Dupla , Zea mays , Epigênese Genética , Meiose/genética , Recombinação Genética , Transcriptoma , Zea mays/metabolismo
20.
Zoolog Sci ; 39(5): 407-412, 2022 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-36205361

RESUMO

Under favorable conditions, daphnids produce only female neonates by parthenogenesis, while they produce male neonates and start sexual reproduction when they detect cues signaling a deteriorating environment. Identifying the regulatory mechanisms of such cyclical parthenogenesis is important for understanding how organisms adapt to environments and expand their habitats. However, most previous studies using the model species Daphnia magna and Daphnia pulex have focused on production of male offspring (sex determination), whereas the process of meiosis induction in females has not been investigated. Here, we report a simple experimental method to induce meiosis effectively in D. pulex females. Through observations using the new method, we describe the process of sexual reproduction along an individual developmental time course. Meiotic oocytes are oviposited only when females mate within a certain time window, and failure to mate within that window results in subsequent resorption of oocytes, a measure that may increase resistance to starvation. These results further our understanding of regulatory mechanisms and evolutionary processes in the complicated life-history of Daphnia.


Assuntos
Daphnia , Partenogênese , Animais , Daphnia/genética , Feminino , Masculino , Meiose , Oócitos , Reprodução
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