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Chang HY, Jennings PC, Stewart J, Verrills NM, Jones KT. Essential role of protein phosphatase 2A in metaphase II arrest and activation of mouse eggs shown by okadaic acid, dominant negative protein phosphatase 2A, and FTY720. J Biol Chem 2011; 286:14705-12. [PMID: 21383018 DOI: 10.1074/jbc.m110.193227] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Vertebrate eggs arrest at second meiotic metaphase. The fertilizing sperm causes meiotic exit through Ca(2+)-mediated activation of the anaphase-promoting complex/cyclosome (APC/C). Although the loss in activity of the M-phase kinase CDK1 is known to be an essential downstream event of this process, the contribution of phosphatases to arrest and meiotic resumption is less apparent, especially in mammals. Therefore, we explored the role of protein phosphatase 2A (PP2A) in mouse eggs using pharmacological inhibition and activation as well as a functionally dominant-negative catalytic PP2A subunit (dn-PP2Ac-L199P) coupled with live cell imaging. We observed that PP2A inhibition using okadaic acid induced events normally observed at fertilization: degradation of the APC/C substrates cyclin B1 and securin resulting from loss of the APC/C inhibitor Emi2. Although sister chromatids separated, chromatin remained condensed, and polar body extrusion was blocked as a result of a rapid spindle disruption, which could be ameliorated by non-degradable cyclin B1, suggesting that spindle integrity was affected by CDK1 loss. Similar cell cycle effects to okadaic acid were also observed using dominant-negative PP2Ac. Preincubation of eggs with the PP2A activator FTY720 could block many of the actions of okadaic acid, including Emi2, cyclin B1, and securin degradation and sister chromatid separation. Therefore, in conclusion, we used okadaic acid, dn-PP2Ac-L199P, and FTY720 on mouse eggs to demonstrate that PP2A is needed to for both continued metaphase arrest and successful exit from meiosis.
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Affiliation(s)
- Heng-Yu Chang
- School of Biomedical Sciences and Pharmacy, University of Newcastle, Callaghan, New South Wales, 2308, Australia
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Bielak-Zmijewska A, Sikora-Polaczek M, Nieznanski K, Mosieniak G, Kolano A, Maleszewski M, Styrna J, Sikora E. Curcumin disrupts meiotic and mitotic divisions via spindle impairment and inhibition of CDK1 activity. Cell Prolif 2010; 43:354-64. [PMID: 20590660 DOI: 10.1111/j.1365-2184.2010.00684.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
OBJECTIVES Curcumin, a natural compound, is a potent anti-cancer agent, which inhibits cell division and/or induces cell death. It is believed that normal cells are less sensitive to curcumin than malignant cells; however, the mechanism(s) responsible for curcumin's effect on normal cells are poorly understood. The aim of this study was to verify the hypothesis that curcumin affects normal cell division by influencing microtubule stability, using mouse oocyte and early embryo model systems. MATERIALS AND METHODS Maturating mouse oocytes and two-cell embryos were treated with different concentrations of curcumin (10-50 microm), and meiotic resumption and mitotic cleavage were analysed. Spindle and chromatin structure were visualized using confocal microscopy. In addition, acetylation and in vitro polymerization of tubulin, in the presence of curcumin, were investigated and the damage to double-stranded DNA was studied using gammaH2A.X. CDK1 activity was measured. RESULTS AND CONCLUSIONS We have shown for the first time, that curcumin, in a dose-dependent manner, delays and partially inhibits meiotic resumption of oocytes and inhibits meiotic and mitotic divisions by causing disruption of spindle structure and does not induce DNA damage. Our analysis indicated that curcumin affects CDK1 kinase activity but does not directly affect microtubule polymerization and tubulin acetylation. As our study showed that curcumin impairs generative and somatic cell division, its future clinical use or of its derivatives with improved bioavailability after oral administration, should take into consideration the possibility of extensive side-effects on normal cells.
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Affiliation(s)
- A Bielak-Zmijewska
- Laboratory of Molecular Bases of Ageing, Nencki Institute of Experimental Biology, PAS, Warsaw, Poland.
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Mailhes JB. Faulty spindle checkpoint and cohesion protein activities predispose oocytes to premature chromosome separation and aneuploidy. ENVIRONMENTAL AND MOLECULAR MUTAGENESIS 2008; 49:642-58. [PMID: 18626998 DOI: 10.1002/em.20412] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Aneuploidy accounts for a major proportion of human reproductive failures, mental and physical anomalies, and neoplasms. To heighten our understanding of normal and abnormal chromosome segregation, additional information is needed about the underlying molecular mechanisms of chromosome segregation. Although many hypotheses have been proposed for the etiology of human aneuploidy, there has not been general acceptance of any specific hypothesis. Moreover, it is important to recognize that many potential mechanisms exist whereby chromosome missegregation may occur. One area for investigating aneuploidy centers on the biochemical changes that take place during oocyte maturation. In this regard, recent results have shown that faulty mRNA of spindle-assembly checkpoint proteins and chromosome cohesion proteins may lead to aneuploidy. Also, postovulatory and in vitro aging of mouse oocytes has been shown to lead to decreased levels of Mad2 transcripts and elevated frequencies of premature centromere separation. The intent of this review is to highlight the major events surrounding chromosome segregation and to present the published results that support the premise that faulty chromosome cohesion proteins and spindle checkpoint proteins compromise accurate chromosome segregation.
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Affiliation(s)
- John B Mailhes
- Department of Obstetrics and Gynecology, LSU Health Sciences Center, Shreveport, Louisiana 71130, USA.
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Mtango NR, Potireddy S, Latham KE. Oocyte quality and maternal control of development. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2008; 268:223-90. [PMID: 18703408 DOI: 10.1016/s1937-6448(08)00807-1] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The oocyte is a unique and highly specialized cell responsible for creating, activating, and controlling the embryonic genome, as well as supporting basic processes such as cellular homeostasis, metabolism, and cell cycle progression in the early embryo. During oogenesis, the oocyte accumulates a myriad of factors to execute these processes. Oogenesis is critically dependent upon correct oocyte-follicle cell interactions. Disruptions in oogenesis through environmental factors and changes in maternal health and physiology can compromise oocyte quality, leading to arrested development, reduced fertility, and epigenetic defects that affect long-term health of the offspring. Our expanding understanding of the molecular determinants of oocyte quality and how these determinants can be disrupted has revealed exciting new insights into the role of oocyte functions in development and evolution.
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Affiliation(s)
- Namdori R Mtango
- Fels Institute for Cancer Research and Molecular Biology, Temple University School of Medicine, Philadelphia, PA 19140, USA
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Harvey AJ, Gibson TC, Quebedeaux TM, Brenner CA. Impact of Assisted Reproductive Technologies: A Mitochondrial Perspective of Cytoplasmic Transplantation. Curr Top Dev Biol 2007; 77:229-49. [PMID: 17222706 DOI: 10.1016/s0070-2153(06)77009-0] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Many of the assisted reproductive techniques associated with maternal aging, disease states, or implantation failure aim to correct poor developmental capacity. These techniques are highly invasive and require the exchange of nuclear or cytoplasmic material from a donor oocyte to compensate for deficiencies inherent in the affected individual. These techniques are based on the assumption that the cytoplasm of the donor oocyte can effectively substitute the necessary component(s) to enable development to proceed. Several studies have attempted to inject cytoplasm from "normal" (young) donors, into aged eggs, again assuming that beneficial components of the cytoplasm are transferred to restore developmental capacity. These invasive assisted reproduction technology (ART) procedures aim to eliminate chromosomal abnormalities, improve the quality of oocytes deficient in some important cytoplasmic factors necessary for maturation and/or subsequent development, and eliminate maternally inherited diseases (particularly mitochondrial myopathies). However, in order to develop such ART, understanding the processes involving mitochondrial DNA replication and transcription is imperative, as asynchrony between mitochondrial and nuclear genomes may cause problems in mitochondrial function, localization, and biogenesis.
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Affiliation(s)
- A J Harvey
- Department of Biology, University of New Orleans New Orleans, Louisiana 70148, USA
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Polit JT, Kazmierczak A. Okadaic acid (1 microM) accelerates S phase and mitosis but inhibits heterochromatin replication and metaphase anaphase transition in Vicia faba meristem cells. JOURNAL OF EXPERIMENTAL BOTANY 2007; 58:2785-97. [PMID: 17609530 DOI: 10.1093/jxb/erm148] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
Protein kinases and phosphatases are the foremost agents which take part in cell cycle regulation in both plants and other eukaryotes. Protein kinases are a very well examined group of proteins with respect to chemical structure and function. Nowadays protein phosphatases, including PP1 and PP2A belonging to the PSP family, are the focus of interest. Okadaic acid (OA) which is a specific inhibitor of protein phosphatase activity is widely used to study them. In the present research, the involvement of OA-sensitive phosphatases in the regulation of progression of the plant cell cycle was analysed (in planta) using Vicia faba root meristems synchronized with hydroxyurea and divided into five series. Each series was treated with 1 muM OA for 3 h for different time periods corresponding to the consecutive cell cycle phases. The results showed that in the OA-treated cells DNA replication and mitosis began earlier than in the control cells, since G(1) and G(2) phases were significantly shorter and the H1 histone kinases activity was higher. Moreover, autoradiography and morphological analyses of mitotic figures revealed that the OA-treated cells entered mitosis before the end of heterochromatin replication. An immunocytochemical search showed that earlier initiation of S phase in the OA-treated cells correlated with more abundant phosphorylation of Rb-like protein in comparison with the control cells. OA also induced significant condensation of metaphase chromosomes and blocked metaphase-anaphase transition.
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Affiliation(s)
- Justyna Teresa Polit
- Department of Cytophysiology, University of Łódź, 90-231 Łódź, ul. Pilarskiego 14, Poland.
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Ben-Aharon I, Haim K, Shalgi R, Ben-Yosef D. Expression and possible involvement of calpain isoforms in mammalian egg activation. Reproduction 2005; 130:165-75. [PMID: 16049154 DOI: 10.1530/rep.1.00602] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
At fertilization in mammals, the spermatozoon triggers a unique signal transduction mechanism within the egg, leading to its activation. It is well accepted that the earliest event observed in all activated eggs is an abrupt rise in intracellular calcium concentrations. However, little is known regarding the downstream proteins that are activated by this rise in calcium. Calpains constitute a family of intracellular calcium-dependent cysteine proteases whose members are expressed widely in a variety of cells. We investigated the expression and possible role of the calpain isoforms mu and m throughout egg activation. Both calpains were expressed in the rat egg and localized at the egg cortex as well as in the meiotic spindle. m Calpain translocated to the membrane and to the spindle area during parthenogenetic egg activation and during in vivo fertilization, upon sperm binding to the egg. The cytoskeletal protein alpha-spectrin (fodrin) was proteolysed by calpain during the egg-activation process, as demonstrated by specific calpain-breakdown products. Following parthenogenetic activation by ionomycin or puromycin, the calpain-selective permeable inhibitor, calpeptin, inhibited the resumption of meiosis and cortical reaction in a dose-dependent manner. Calpeptin was also effective in inhibiting in vitro fertilization. These results may imply a correlation between calpain activation and mammalian egg activation at fertilization and a possible role for calpain in the cascade of cellular events leading to resumption of meiosis.
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Affiliation(s)
- Irit Ben-Aharon
- Department of Cell and Developmental Biology, Sackler Faculty of Medicine, Tel Aviv University, Tel-Aviv, Israel
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Di Agostino S, Botti F, Di Carlo A, Sette C, Geremia R. Meiotic progression of isolated mouse spermatocytes under simulated microgravity. Reproduction 2004; 128:25-32. [PMID: 15232061 DOI: 10.1530/rep.1.00184] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Progression through the prophase of the first meiotic division can be obtained in culture by treatment of mouse spermatocytes with the serine/threonine phosphatase inhibitor okadaic acid. Chromosome condensation during this G2/M transition involves the activation of the MAPK pathway, which causes the activation of Nek2 and the phosphorylation of the chromatin architectural protein Hmga2. In an effort to set up conditions to allow a spontaneous progression of mouse spermatocytes through meiosis, we have investigated the cell-cycle features of these cells cultured for 24 h with a rotary cell culture system in a humidified atmosphere in a thermostatic incubator to simulate a microgravity environment. Morphological analysis of nuclear squashes indicated a 2-fold increase in late-pachytene spermatocytes with highly condensed chromosomes, and a contemporaneous decrease of mid-pachytene cells with less condensed chromatin. Microgravity induced a 2-fold activation of the cyclinB–cdc2 complex, confirming at the molecular level that cell-cycle progression had occurred. Moreover, using immuno-kinase assays with specific substrates we have demonstrated that the meiotic progression obtained under microgravity conditions is accompanied by activation of the Erk1/p90Rsk2 pathway. These data indicated that activation of the MAPK pathway correlates with chromatin condensation even under conditions in which meiotic progression occurs spontaneously and is not induced by a drug. We suggest that culture under microgravity conditions might help to release the block that inhibits isolated spermatocytes from progressing through prophase at unit gravity, and to study the physiological events of germ cell differentiationin vitro.
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Affiliation(s)
- Silvia Di Agostino
- Dipartimento di Sanità Pubblica e Biologia Cellulare, Università di Roma 'Tor Vergata', Via Montpellier 1, 00133, Rome, Italy
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Mailhes JB, Hilliard C, Fuseler JW, London SN. Okadaic acid, an inhibitor of protein phosphatase 1 and 2A, induces premature separation of sister chromatids during meiosis I and aneuploidy in mouse oocytes in vitro. Chromosome Res 2004; 11:619-31. [PMID: 14516070 DOI: 10.1023/a:1024909119593] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Recent advances in understanding some of the molecular aspects of chromosome segregation during mitosis and meiosis provide a background for investigating potential mechanisms of aneuploidy in mammalian germ cells. Numerous protein kinases and phosphatases have important functions during mitosis and meiosis. Alterations in these enzyme activities may upset the normal temporal sequence of biochemical reactions and cellular organelle modifications required for orderly chromosome segregation. Protein phosphatases 1 (PP1) and 2A (PP2A) play integral roles in regulating oocyte maturation (OM) and the metaphase-anaphase transitions. Mouse oocytes were transiently exposed in vitro to different dosages (0, 0.01, 0.1, or 1.0 microg/ml) of the PP1 and PP2A phosphatase inhibitor okadaic acid (OA) during meiosis I and oocytes were cytogenetically analyzed. Significant (p < 0.05) OA dose-response increases in the frequencies of metaphase I (MI) arrested oocytes, MI oocytes with 80 chromatids instead of the normal 20 tetrads, and anaphase I telophase I (AI-TI) oocytes with two groups of an unequal number of chromatids were found. Analysis of MII oocytes revealed significant (p < 0.05) increases in the frequencies of premature sister chromatid separation, single-unpaired chromatids, and hyperploidy. Besides showing that OA is aneugenic, these data suggest that OA-induced protein phosphatase inhibition upsets the normal kinase-phosphatase equilibrium during mouse OM, resulting in precocious removal of cohesion proteins from chromosomes.
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Affiliation(s)
- John B Mailhes
- Department of Obstetrics and Gynecology, Louisiana State University Health Sciences Center, PO Box 33932, Shreveport, Louisiana 71130, USA.
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Sun QY, Wu GM, Lai L, Bonk A, Cabot R, Park KW, Day BN, Prather RS, Schatten H. Regulation of mitogen-activated protein kinase phosphorylation, microtubule organization, chromatin behavior, and cell cycle progression by protein phosphatases during pig oocyte maturation and fertilization in vitro. Biol Reprod 2002; 66:580-8. [PMID: 11870061 DOI: 10.1095/biolreprod66.3.580] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Abstract
We used okadaic acid (OA), a potent inhibitor of protein phosphatases 1 and 2A, to study the regulatory effects of protein phosphatases on mitogen-activated protein (MAP) kinase phosphorylation, morphological changes in the nucleus, and microtubule assembly during pig oocyte maturation and fertilization in vitro. When germinal vesicle (GV) stage oocytes were exposed to OA, MAP kinase phosphorylation was greatly accelerated, being fully activated at 10 min. However, MAP kinase was dephosphorylated by long-term (>20 h) exposure to OA. Correspondingly, premature chromosome condensation and GV breakdown were accelerated, whereas meiotic spindle assembly and meiotic progression beyond metaphase I stage were inhibited. OA also quickly reversed the inhibitory effects of butyrolactone I, a specific inhibitor of maturation-promoting factor (MPF), on MAP kinase phosphorylation and meiosis resumption. Treatment of metaphase II oocytes triggered metaphase II spindle elongation and disassembly as well as chromosome alignment disruption. OA treatment of fertilized eggs resulted in prompt phosphorylation of MAP kinase, disassembly of microtubules around the pronuclear area, chromatin condensation, and pronuclear membrane breakdown, but inhibited further cleavage. Our results suggest that inhibition of protein phosphatases promptly phosphorylates MAP kinase, induces premature chromosome condensation and meiosis resumption as well as pronucleus breakdown, but inhibits spindle organization and suppresses microtubule assembly by sperm centrosomes in pig oocytes and fertilized eggs.
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Affiliation(s)
- Qing-Yuan Sun
- Department of Veterinary Pathobiology, University of Missouri-Columbia, Columbia, Missouri 65211, USA
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Shea TB. Induction of lysosomal abnormalities and tau hyperphosphorylation in human neuroblastoma cells by colchicine and okadaic acid: Evidence that microtubule disruption contributes to alzheimer neurodegeneration. ACTA ACUST UNITED AC 1999. [DOI: 10.1002/(sici)1520-6769(199607)19:1<27::aid-nrc160>3.0.co;2-g] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Bonivento P, Battistella S, Amirante GA. Recognition of a 31,000 molecular weight protein synthesized by the mussel Mytilus galloprovincialis Lmk. during Dinophysis spp. algal bloom in the Gulf of Trieste (upper Adriatic Sea). Toxicon 1997; 35:1347-50. [PMID: 9278983 DOI: 10.1016/s0041-0101(96)00220-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
During Dinophysis spp. bloom, a histological alteration in the digestive gland of Mytilus galloprovincialis Lmk. occurs. Electrophoretic analysis of the water-soluble proteins of the hepatopancreas showed the presence of a low mol. wt protein, which appeared after the ingestion of algae by mussels. The probable relationship between the toxicity of Dinophysis and the synthesis of the new protein by mussels prompted us to produce a monoclonal antibody against this protein because it should be useful for the identification of mussel toxicity.
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Affiliation(s)
- P Bonivento
- Department of Biology, University of Trieste, Italy
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Grocholová R, Petr J, Rozinek J, Jílek F. The protein phosphatase inhibitor okadaic acid inhibits exit from metaphase II in parthenogenetically activated pig oocytes. ACTA ACUST UNITED AC 1997. [DOI: 10.1002/(sici)1097-010x(19970101)277:1<49::aid-jez5>3.0.co;2-b] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Wang W, Himes R, Dentler W. The binding of a ciliary microtubule plus-end binding protein complex to microtubules is regulated by ciliary protein kinase and phosphatase activities. J Biol Chem 1994. [DOI: 10.1016/s0021-9258(17)31826-4] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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