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Scientific Reports Aug 2017Mulberry (Morus spp.), in family Moraceae, is a plant with important economic value. Many polyploid levels of mulberry have been determined. In the present study, the...
Mulberry (Morus spp.), in family Moraceae, is a plant with important economic value. Many polyploid levels of mulberry have been determined. In the present study, the fluorescence in situ hybridization (FISH) technique was applied in Morus notabilis, using four single-copy sequences, telomere repeats, and 5S and 25S rDNAs as probes. All the mitotic chromosomes were clearly identified and grouped into seven pairs of homologous chromosomes. Three dot chromosome pairs were distinguished by the FISH patterns of the 25S rDNA probe and a simple sequence repeat (SSR2524). According to the FISH signals, chromosome length and morphology, detailed meiotic diakinesis karyotype was constructed. Interestingly, only six bivalent chromosomes were observed in diakinesis cells. The 25S rDNA probe was used to illustrate chromosome alterations. The results indicated that mitotic chromosomes 5 and 7 fused into diakinesis chromosome 5 during the meiotic phase. In mitotic cells, the fused chromosome 5 broke into chromosomes 5 and 7. A chromosomal fusion-fission cycle between the meiotic and mitotic phases in the same individual is reported here for the first time. This finding will contribute to the understanding of karyotype evolution in plants.
Topics: Cell Cycle; Chromosome Mapping; Chromosomes, Plant; DNA, Ribosomal; In Situ Hybridization, Fluorescence; Karyotype; Meiosis; Mitosis; Morus; RNA, Ribosomal
PubMed: 28852033
DOI: 10.1038/s41598-017-10079-6 -
Chromosome Research : An International... 2007The sensing of accurate homologous recognition and pairing between discreet chromosomal regions and/or entire chromosomes entering meiosis is an essential step in... (Review)
Review
The sensing of accurate homologous recognition and pairing between discreet chromosomal regions and/or entire chromosomes entering meiosis is an essential step in ensuring correct alignment for recombination. A component of this is the recognition of heterology, which is required to prevent recombination at ectopic sites and between non-homologous chromosomes. It has been observed that a number of diverged organisms add an additional layer to this process: regions or chromosomes without a homologous counterpart are targeted for silencing during meiotic prophase I. This phenomenon was originally described in filamentous fungi, but has since been observed in nematodes and mammals. In this review we will generally group these phenomena under the title of meiotic silencing, and describe what is known about the process in the organisms in which it is observed. We will additionally propose that the functions of meiotic silencing originate in genome defense, and discuss its potential contributions to genome evolution and speciation.
Topics: Animals; Biological Evolution; Caenorhabditis elegans; Chromatin Assembly and Disassembly; Chromosome Pairing; Drosophila; Epigenesis, Genetic; Female; Gene Silencing; Genomic Imprinting; Male; Mammals; Meiosis; Models, Genetic; Neurospora crassa; RNA Interference; Recombination, Genetic; X Chromosome; X Chromosome Inactivation
PubMed: 17674151
DOI: 10.1007/s10577-007-1143-0 -
Cellular and Molecular Life Sciences :... Apr 2012Mammalian oocytes grow and undergo meiosis within ovarian follicles. Fully grown oocytes are arrested at the first meiotic prophase by a mural granulosa origin... (Review)
Review
Mammalian oocytes grow and undergo meiosis within ovarian follicles. Fully grown oocytes are arrested at the first meiotic prophase by a mural granulosa origin "arrester" until a surge of luteinizing hormone (LH) from the pituitary at the mid-cycle stimulates the immature oocyte to resume meiosis. Recent evidence indicates that natriuretic peptide precursor type C (NPPC) produced by mural granulosa cells stimulates the generation of cyclic guanosine 3',5'-monophosphate (cGMP) by cumulus cell natriuretic peptide receptor 2 (NPR2), which diffuses into oocyte via gap junctions and inhibits oocyte phosphodiesterase 3A (PDE3A) activity and cyclic adenosine 3',5'-monophosphate (cAMP) hydrolysis and maintains meiotic arrest with a high intraoocyte cAMP level. This cAMP is generated through the activity of the Gs G-protein by the G-protein-coupled receptor, GPR3 and GPR12, and adenylyl cyclases (ADCY) endogenous to the oocyte. Further studies suggest that endocrine hormones, such as follicle-stimulating hormone (FSH), LH, 17β-estradiol (E2) and oocyte-derived paracrine factors (ODPFs), participate in oocyte meiosis possibly by the regulation of NPPC and/or NPR2. A detailed investigation of NPPC and NPR2 expression in follicle cells will elucidate the precise molecular mechanisms of gonadotropins, and control the arrest as well as resumption of meiosis.
Topics: Animals; Cyclic AMP; Cyclic GMP; Female; Hormones; Humans; Meiotic Prophase I; Oocytes
PubMed: 22045555
DOI: 10.1007/s00018-011-0867-3 -
Cell Jun 2020Meiosis is the specialized cell division that generates haploid gametes and is therefore essential for sexual reproduction. This SnapShot encompasses key events taking...
Meiosis is the specialized cell division that generates haploid gametes and is therefore essential for sexual reproduction. This SnapShot encompasses key events taking place during prophase I of meiosis that are required for achieving proper chromosome segregation and highlights how these are both conserved and diverged throughout five different species. To view this SnapShot, open or download the PDF.
Topics: Animals; Arabidopsis; Caenorhabditis elegans; Chromosome Segregation; Drosophila melanogaster; Meiosis; Meiotic Prophase I; Mice; Saccharomyces cerevisiae
PubMed: 32531249
DOI: 10.1016/j.cell.2020.04.038 -
Annual Review of Genetics Nov 2016Meiosis, the mechanism of creating haploid gametes, is a complex cellular process observed across sexually reproducing organisms. Fundamental to meiosis is the process... (Review)
Review
Meiosis, the mechanism of creating haploid gametes, is a complex cellular process observed across sexually reproducing organisms. Fundamental to meiosis is the process of homologous recombination, whereby DNA double-strand breaks are introduced into the genome and are subsequently repaired to generate either noncrossovers or crossovers. Although homologous recombination is essential for chromosome pairing during prophase I, the resulting crossovers are critical for maintaining homolog interactions and enabling accurate segregation at the first meiotic division. Thus, the placement, timing, and frequency of crossover formation must be exquisitely controlled. In this review, we discuss the proteins involved in crossover formation, the process of their formation and designation, and the rules governing crossovers, all within the context of the important landmarks of prophase I. We draw together crossover designation data across organisms, analyze their evolutionary divergence, and propose a universal model for crossover regulation.
Topics: Aneuploidy; Animals; Crossing Over, Genetic; DNA Breaks, Double-Stranded; DNA Repair; Meiosis; Meiotic Prophase I; Protein Processing, Post-Translational; Recombination, Genetic; Synaptonemal Complex
PubMed: 27648641
DOI: 10.1146/annurev-genet-120215-035111 -
Cell Cycle (Georgetown, Tex.) 2022Mammalian oocytes undergo two rounds of developmental arrest during maturation: at the diplotene of the first meiotic prophase and metaphase of the second meiosis. These... (Review)
Review
Mammalian oocytes undergo two rounds of developmental arrest during maturation: at the diplotene of the first meiotic prophase and metaphase of the second meiosis. These arrests are strictly regulated by follicular cells temporally producing the secondary messengers, cAMP and cGMP, and other factors to regulate maturation promoting factor (composed of cyclin B1 and cyclin-dependent kinase 1) levels in the oocytes. Out of these normally appearing developmental arrests, permanent arrests may occur in the oocytes at germinal vesicle (GV), metaphase I (MI), or metaphase II (MII) stage. This issue may arise from absence or altered expression of the oocyte-related genes playing key roles in nuclear and cytoplasmic maturation. Additionally, the assisted reproductive technology (ART) applications such as ovarian stimulation and culture conditions both of which harbor various types of chemical agents may contribute to forming the permanent arrests. In this review, the molecular determinants of developmental and permanent arrests occurring in the mammalian oocytes are comprehensively evaluated in the light of current knowledge. As number of permanently arrested oocytes at different stages is increasing in ART centers, potential approaches for inducing permanent arrests to obtain competent oocytes are discussed.
Topics: Animals; Mammals; Meiosis; Meiotic Prophase I; Metaphase; Oocytes
PubMed: 35072590
DOI: 10.1080/15384101.2022.2026704 -
Cell Cycle (Georgetown, Tex.) 2014During meiosis, rapid chromosome movements within the nucleus enable homologous chromosomes to acquire physical juxtaposition. In most organisms, chromosome ends,... (Review)
Review
During meiosis, rapid chromosome movements within the nucleus enable homologous chromosomes to acquire physical juxtaposition. In most organisms, chromosome ends, telomeres, tethered to the transmembrane LINC-complex mediate this movement by transmitting cytoskeletal forces to the chromosomes. While the majority of molecular studies have been performed using lower eukaryotes as model systems, recent studies have identified mammalian meiotic telomere regulators, including the LINC-complex SUN1/KASH5 and the meiosis-specific telomere binding protein TERB1. This review highlights the molecular regulations of mammalian meiotic telomeres in comparison with other model systems and discusses some future perspectives.
Topics: Animals; Carrier Proteins; Cell Cycle Proteins; Chromosomes, Mammalian; Cytoskeletal Proteins; Mammals; Meiosis; Meiotic Prophase I; Microtubule-Associated Proteins; Nuclear Proteins; Telomere
PubMed: 24870409
DOI: 10.4161/cc.29350 -
ADAD2 interacts with RNF17 in P-bodies to repress the Ping-pong cycle in pachytene piRNA biogenesis.The Journal of Cell Biology May 2023Pachytene piRNA biogenesis is a hallmark of the germline, distinct from another wave of pre-pachytene piRNA biogenesis with regard to the lack of a secondary...
Pachytene piRNA biogenesis is a hallmark of the germline, distinct from another wave of pre-pachytene piRNA biogenesis with regard to the lack of a secondary amplification process known as the Ping-pong cycle. However, the underlying molecular mechanism and the venue for the suppression of the Ping-pong cycle remain elusive. Here, we showed that a testis-specific protein, ADAD2, interacts with a TDRD family member protein RNF17 and is associated with P-bodies. Importantly, ADAD2 directs RNF17 to repress Ping-pong activity in pachytene piRNA biogenesis. The P-body localization of RNF17 requires the intrinsically disordered domain of ADAD2. Deletion of Adad2 or Rnf17 causes the mislocalization of each other and subsequent Ping-pong activity derepression, secondary piRNAs overproduced, and disruption of P-body integrity at the meiotic stage, thereby leading to spermatogenesis arrested at the round spermatid stage. Collectively, by identifying the ADAD2-dependent mechanism, our study reveals a novel function of P-bodies in suppressing Ping-pong activity in pachytene piRNA biogenesis.
Topics: Male; Meiotic Prophase I; Piwi-Interacting RNA; Processing Bodies; RNA, Small Interfering; Spermatogenesis
PubMed: 36930220
DOI: 10.1083/jcb.202206067 -
Trends in Biochemical Sciences Jul 2009Throughout spermatogenesis, a select pool of germ cells, the leptotene spermatocytes, must traverse the blood-testis barrier (BTB) to enter the adluminal compartment of... (Review)
Review
Throughout spermatogenesis, a select pool of germ cells, the leptotene spermatocytes, must traverse the blood-testis barrier (BTB) to enter the adluminal compartment of the seminiferous epithelium. This event requires extensive restructuring of cell junctions, and it must also coincide with germ cell cycle progression in preparation for primary spermatocyte meiosis. Recent findings show that cell-cycle-associated kinases and phosphatases, including mitogen-activated protein kinases (MAPKs), participate in the pathways that also direct germ cell adhesion and movement. Our new biochemical model explains, in part, how two distinct cellular events, BTB restructuring and spermiation, are coordinated to maintain spermatogenesis and fertility. In this way, MAPKs would synchronize cell cycle progression in primary spermatocytes with junction remodeling and cell migration across the BTB.
Topics: Animals; Blood-Testis Barrier; Cell Cycle; Cell Movement; Desmosomes; Humans; Intercellular Junctions; Male; Meiotic Prophase I; Models, Biological; Phosphoprotein Phosphatases; Protein Kinases; Spermatogenesis
PubMed: 19535250
DOI: 10.1016/j.tibs.2009.03.005 -
The International Journal of... 2015From previous and more recent works reviewed in the present paper, it appears that mammalian fetal oocytes face several challenges to survive throughout the stages of... (Review)
Review
From previous and more recent works reviewed in the present paper, it appears that mammalian fetal oocytes face several challenges to survive throughout the stages of meiotic prophase I up to the block at the diplotene/dictyate stage and the primordial follicle assembly. Depending on the period of development and experimental conditions, these oocytes can undergo different forms of programmed cell death (PCD) and cross-talking pathways. We hypothesize that they require the continuous support of growth factors to accomplish the activities required to overcome PCD during prophase I. An extraordinary level of DNA double strand break (DSB) tolerance characterizes oocytes during the first stages of meiotic prophase I. However, the activation of a p63/p53-and PCNA-dependent DNA damage checkpoint, plays a major role in eliminating defective oocytes when they reach the diplotene stage. Before oocytes are enclosed into a primordial follicle, the shortness of nutrients/growth factors might activate protective autophagy but this can turn into their death if starvation is prolonged. Actually, clarifying the relationships among growth factor signalling (mainly AKT cascade), apoptotic and autophagic proteins that seem to coexist in fetal oocytes, could be the key to understanding PCD in these cells.
Topics: Animals; Apoptosis; Autophagy; DNA Damage; Female; Mammals; Oocytes; Oogenesis; Ovarian Follicle; Ovary; Proliferating Cell Nuclear Antigen; Transcription Factors; Tumor Suppressor Protein p53; Tumor Suppressor Proteins
PubMed: 26374525
DOI: 10.1387/ijdb.150063fk