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Miglietta S, Cristiano L, Espinola MSB, Masiello MG, Micara G, Battaglione E, Linari A, Palmerini MG, Familiari G, Aragona C, Bizzarri M, Macchiarelli G, Nottola SA. Effects of Simulated Microgravity In Vitro on Human Metaphase II Oocytes: An Electron Microscopy-Based Study. Cells 2023; 12:1346. [PMID: 37408181 DOI: 10.3390/cells12101346] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2023] [Revised: 05/04/2023] [Accepted: 05/05/2023] [Indexed: 07/07/2023] Open
Abstract
The Gravity Force to which living beings are subjected on Earth rules the functionality of most biological processes in many tissues. It has been reported that a situation of Microgravity (such as that occurring in space) causes negative effects on living beings. Astronauts returning from space shuttle missions or from the International Space Station have been diagnosed with various health problems, such as bone demineralization, muscle atrophy, cardiovascular deconditioning, and vestibular and sensory imbalance, including impaired visual acuity, altered metabolic and nutritional status, and immune system dysregulation. Microgravity has profound effects also on reproductive functions. Female astronauts, in fact, suppress their cycles during space travels, and effects at the cellular level in the early embryo development and on female gamete maturation have also been observed. The opportunities to use space flights to study the effects of gravity variations are limited because of the high costs and lack of repeatability of the experiments. For these reasons, the use of microgravity simulators for studying, at the cellular level, the effects, such as those, obtained during/after a spatial trip, are developed to confirm that these models can be used in the study of body responses under conditions different from those found in a unitary Gravity environment (1 g). In view of this, this study aimed to investigate in vitro the effects of simulated microgravity on the ultrastructural features of human metaphase II oocytes using a Random Positioning Machine (RPM). We demonstrated for the first time, by Transmission Electron Microscopy analysis, that microgravity might compromise oocyte quality by affecting not only the localization of mitochondria and cortical granules due to a possible alteration of the cytoskeleton but also the function of mitochondria and endoplasmic reticulum since in RPM oocytes we observed a switch in the morphology of smooth endoplasmic reticulum (SER) and associated mitochondria from mitochondria-SER aggregates to mitochondria-vesicle complexes. We concluded that microgravity might negatively affect oocyte quality by interfering in vitro with the normal sequence of morphodynamic events essential for acquiring and maintaining a proper competence to fertilization in human oocytes.
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Affiliation(s)
- Selenia Miglietta
- Department of Anatomy, Histology, Forensic Medicine and Orthopaedics, Sapienza University, 00165 Rome, Italy
| | - Loredana Cristiano
- Department of Life, Health and Environmental Sciences, University of L'Aquila, 67100 L'Aquila, Italy
| | - Maria Salomé B Espinola
- Systems Biology Group, Department of Experimental Medicine, Sapienza University, 00165 Rome, Italy
| | - Maria Grazia Masiello
- Systems Biology Group, Department of Experimental Medicine, Sapienza University, 00165 Rome, Italy
| | - Giulietta Micara
- Department of Maternal, Infantile and Urological Sciences, Sapienza University, 00165 Rome, Italy
| | - Ezio Battaglione
- Department of Anatomy, Histology, Forensic Medicine and Orthopaedics, Sapienza University, 00165 Rome, Italy
| | - Antonella Linari
- Department of Maternal, Infantile and Urological Sciences, Sapienza University, 00165 Rome, Italy
| | - Maria Grazia Palmerini
- Department of Life, Health and Environmental Sciences, University of L'Aquila, 67100 L'Aquila, Italy
| | - Giuseppe Familiari
- Department of Anatomy, Histology, Forensic Medicine and Orthopaedics, Sapienza University, 00165 Rome, Italy
| | - Cesare Aragona
- Systems Biology Group, Department of Experimental Medicine, Sapienza University, 00165 Rome, Italy
| | - Mariano Bizzarri
- Systems Biology Group, Department of Experimental Medicine, Sapienza University, 00165 Rome, Italy
| | - Guido Macchiarelli
- Department of Life, Health and Environmental Sciences, University of L'Aquila, 67100 L'Aquila, Italy
| | - Stefania A Nottola
- Department of Anatomy, Histology, Forensic Medicine and Orthopaedics, Sapienza University, 00165 Rome, Italy
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The Role of Mitochondria in Oocyte Maturation. Cells 2021; 10:cells10092484. [PMID: 34572133 PMCID: PMC8469615 DOI: 10.3390/cells10092484] [Citation(s) in RCA: 112] [Impact Index Per Article: 37.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2021] [Revised: 09/09/2021] [Accepted: 09/16/2021] [Indexed: 12/13/2022] Open
Abstract
With the nucleus as an exception, mitochondria are the only animal cell organelles containing their own genetic information, called mitochondrial DNA (mtDNA). During oocyte maturation, the mtDNA copy number dramatically increases and the distribution of mitochondria changes significantly. As oocyte maturation requires a large amount of ATP for continuous transcription and translation, the availability of the right number of functional mitochondria is crucial. There is a correlation between the quality of oocytes and both the amount of mtDNA and the amount of ATP. Suboptimal conditions of in vitro maturation (IVM) might lead to changes in the mitochondrial morphology as well as alternations in the expression of genes encoding proteins associated with mitochondrial function. Dysfunctional mitochondria have a lower ability to counteract reactive oxygen species (ROS) production which leads to oxidative stress. The mitochondrial function might be improved with the application of antioxidants and significant expectations are laid on the development of new IVM systems supplemented with mitochondria-targeted reagents. Different types of antioxidants have been tested already on animal models and human rescue IVM oocytes, showing promising results. This review focuses on the recent observations on oocytes’ intracellular mitochondrial distribution and on mitochondrial genomes during their maturation, both in vivo and in vitro. Recent mitochondrial supplementation studies, aiming to improve oocyte developmental potential, are summarized.
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Ferrer-Vaquer A, Barragán M, Rodríguez A, Vassena R. Altered cytoplasmic maturation in rescued in vitro matured oocytes. Hum Reprod 2020; 34:1095-1105. [PMID: 31119269 DOI: 10.1093/humrep/dez052] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2018] [Revised: 02/26/2019] [Accepted: 03/28/2019] [Indexed: 11/13/2022] Open
Abstract
STUDY QUESTION Do culture conditions affect cytoplasmic maturation in denuded immature non-GV oocytes? SUMMARY ANSWER The maturation rate of denuded non-GV oocytes is not affected by culture media, but in vitro maturation seems to alter the mitochondrial membrane potential, endoplasmic reticulum (ER) and actin cytoskeleton compared with in vivo maturation. WHAT IS KNOWN ALREADY In vitro maturation of denuded immature non-GV oocytes benefits cycles with poor in vivo MII oocyte collection, but maturation levels of non-GV oocytes are only scored by polar body extrusion. Since oocyte maturation involves nuclear as well as cytoplasmic maturation for full meiotic competence, further knowledge is needed about cytoplasmic maturation in in vitro culture. STUDY DESIGN, SIZE, DURATION This basic research study was carried out between January 2017 and September 2018. PARTICIPANTS/MATERIALS, SETTING, METHODS A total of 339 denuded immature non-GV oocytes were cultured in SAGE 1-Step (177) or G-2 PLUS (162) for 6-8 h after retrieval, and 72 in vivo matured MII oocytes were used as controls. Cultured immature non-GV oocytes were scored for polar body extrusion and analysed for mitochondrial membrane potential (ΔΨm), ER clusters, cortical granules number and distribution, spindle morphology and actin cytoskeleton organization. The obtained parameter values were compared to in vivo matured MII oocyte parameter values. MAIN RESULTS AND THE ROLE OF CHANCE The maturation rates of oocytes cultured in G-2 PLUS and SAGE 1-Step were similar (65% vs 64.2%; P = 0.91). The differences observed in cortical granule density were not statistically significant. Also spindle morphometric parameters were mostly similar between in vitro and in vivo matured MII oocytes. However, the number of ER clusters, the ΔΨm and the cortical actin thickness showed significant differences between in vivo MII oocytes and denuded immature non-GV oocytes cultured in vitro until meiosis completion. LIMITATIONS, REASONS FOR CAUTION Frozen-thawed oocytes together with fresh oocytes were used as controls. Due to technical limitations (fixation method and fluorochrome overlap), only one or two parameters could be studied per oocyte. Thus, a global view of the maturation status for each individual oocyte could not be obtained. WIDER IMPLICATIONS OF THE FINDINGS Characterization of in vitro matured oocytes at the cellular level will help us to understand the differences observed in the clinical outcomes reported with rescue IVM compared to in vivo MII oocytes and to improve the culture methods applied. STUDY FUNDING/COMPETING INTEREST(S) This work was supported by intramural funding of Clinica Eugin and by the Torres Quevedo Program to A.F.-V. from the Spanish Ministry of Economy and Competitiveness. No competing interests are declared.
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Sowińska N, Müller K, Niżański W, Jewgenow K. Mitochondrial characteristics in oocytes of the domestic cat (Felis catus
) after in vitro maturation and vitrification. Reprod Domest Anim 2017; 52:806-813. [DOI: 10.1111/rda.12982] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2016] [Accepted: 03/16/2017] [Indexed: 11/28/2022]
Affiliation(s)
- N Sowińska
- Department of Reproduction Biology; Leibniz Institute for Zoo and Wildlife Research; Berlin Germany
- Department of Reproduction and Clinic of Farm Animals; Wroclaw University of Environmental and Life Science; Wroclaw Poland
- Center of Experimental and Innovative Medicine; University Center of Veterinary Medicine JU-AU; University of Agriculture in Krakow; Krakow Poland
| | - K Müller
- Department of Reproduction Biology; Leibniz Institute for Zoo and Wildlife Research; Berlin Germany
| | - W Niżański
- Department of Reproduction and Clinic of Farm Animals; Wroclaw University of Environmental and Life Science; Wroclaw Poland
| | - K Jewgenow
- Department of Reproduction Biology; Leibniz Institute for Zoo and Wildlife Research; Berlin Germany
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Segovia Y, Victory N, Peinado I, García-Valverde LM, García M, Aizpurua J, Monzó A, Gómez-Torres MJ. Ultrastructural characteristics of human oocytes vitrified before and after in vitro maturation. J Reprod Dev 2017; 63:377-382. [PMID: 28458301 PMCID: PMC5593089 DOI: 10.1262/jrd.2017-009] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
The development of an effective program that combines in vitro maturation (IVM) and cryopreservation for immature oocytes would represent a novel advance for in vitro fertilization (IVF), especially as a means to preserve the fertility of women in unique situations. The aim of this study was to analyze the ultrastructural characteristics of human oocytes, obtained after controlled ovarian stimulation, to determine whether IVM is best performed before or after vitrification. To this end, we analyzed the following features in a total of 22 MII oocytes: size, zona pellucida and perivitelline space, mitochondria number, M-SER (mitochondria-smooth endoplasmic reticulum) aggregates and M-V (mitochondria-vesicle) complexes, the number of cortical granules and microvilli, and the presence of vacuolization using transmission electron microscopy (TEM). Each oocyte presented a rounded shape, with an intact oolemma, and was surrounded by a continuous zona pellucida and perivitelline space. Statistical analysis comparing oocytes vitrified before or after IVM indicated that there were no significant differences between examined characteristics.
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Affiliation(s)
- Yolanda Segovia
- Departamento de Biotecnología, Facultad de Ciencias, Universidad de Alicante, Alicante, Spain
| | - Noemí Victory
- Departamento de Biotecnología, Facultad de Ciencias, Universidad de Alicante, Alicante, Spain
| | - Irene Peinado
- Unidad de Reproducción Humana, Hospital La Fe, Valencia, Spain
| | | | - Magdalena García
- Departamento de Biotecnología, Facultad de Ciencias, Universidad de Alicante, Alicante, Spain
| | - Jon Aizpurua
- IVF Spain, Medicina Reproductiva, Alicante, Spain.,Cátedra Human Fertility, Universidad de Alicante, Alicante, Spain
| | - Ana Monzó
- Unidad de Reproducción Humana, Hospital La Fe, Valencia, Spain
| | - María José Gómez-Torres
- Departamento de Biotecnología, Facultad de Ciencias, Universidad de Alicante, Alicante, Spain.,Cátedra Human Fertility, Universidad de Alicante, Alicante, Spain
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Takahashi Y, Hashimoto S, Yamochi T, Goto H, Yamanaka M, Amo A, Matsumoto H, Inoue M, Ito K, Nakaoka Y, Suzuki N, Morimoto Y. Dynamic changes in mitochondrial distribution in human oocytes during meiotic maturation. J Assist Reprod Genet 2016; 33:929-38. [PMID: 27117688 DOI: 10.1007/s10815-016-0716-2] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2015] [Accepted: 04/11/2016] [Indexed: 11/28/2022] Open
Abstract
PURPOSE The change of mitochondrial distribution in human oocytes during meiotic maturation was assessed using 223 human oocytes donated from patients undergoing fertility treatment between June 2013 and February 2016. METHODS Live cell images of fluorescence-labelled mitochondria in human oocytes were analysed to investigate dynamic changes in mitochondrial distribution during meiotic maturation using a confocal microscope combined with an incubator in the presence or absence of colchicine and cytochalasin B, inhibitors for tubulin and actin filament, respectively. Subcellular distribution of mitochondria in human oocytes was also assessed at various stages using a transmission electron microscope (TEM). RESULTS Live cell imaging analysis revealed that the mitochondria-occupied cytoplasmic area decreased from 83 to 77 % of the total cytoplasmic area around 6 h before germinal vesicle breakdown (GVBD) and that mitochondria accumulated preferentially close to the perinuclear region. Then, the mitochondria-distributed area rapidly increased to 85 % of total cytoplasm at the time of GVBD. On the other hand, there was no significant change in mitochondrial distribution before and after polar body extrusion. Such changes in mitochondrial localization were affected differently by colchicine and cytochalasin B. Most of mitochondria in the cytoplasm formed cluster-like aggregates before GVBD while they distributed homogeneously after GVBD. CONCLUSIONS Most mitochondria localized predominantly in the non-cortical region of the cytoplasm of GV stage-oocytes, while the mitochondria-occupied area decreased transiently before GVBD and increased rapidly to occupy the entire area of the cytoplasm at GVBD by some cytoskeleton-dependent mechanism.
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Affiliation(s)
- Yuki Takahashi
- IVF Namba Clinic, 1-17-28 Minamihorie, Nishi-ku, Osaka, 550-0015, Japan
| | - Shu Hashimoto
- IVF Namba Clinic, 1-17-28 Minamihorie, Nishi-ku, Osaka, 550-0015, Japan.
| | - Takayuki Yamochi
- IVF Namba Clinic, 1-17-28 Minamihorie, Nishi-ku, Osaka, 550-0015, Japan
| | - Hiroya Goto
- IVF Namba Clinic, 1-17-28 Minamihorie, Nishi-ku, Osaka, 550-0015, Japan
| | - Masaya Yamanaka
- IVF Namba Clinic, 1-17-28 Minamihorie, Nishi-ku, Osaka, 550-0015, Japan
| | - Ami Amo
- IVF Namba Clinic, 1-17-28 Minamihorie, Nishi-ku, Osaka, 550-0015, Japan
| | - Hiroshi Matsumoto
- IVF Namba Clinic, 1-17-28 Minamihorie, Nishi-ku, Osaka, 550-0015, Japan
| | - Masayasu Inoue
- IVF Namba Clinic, 1-17-28 Minamihorie, Nishi-ku, Osaka, 550-0015, Japan
| | - Keijiro Ito
- IVF Namba Clinic, 1-17-28 Minamihorie, Nishi-ku, Osaka, 550-0015, Japan
| | - Yoshiharu Nakaoka
- IVF Namba Clinic, 1-17-28 Minamihorie, Nishi-ku, Osaka, 550-0015, Japan
| | - Nao Suzuki
- Department of Obstetrics and Gynecology, St. Marianna University School of Medicine, Kanagawa, Japan
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Marchetti F, Massarotti A, Yauk CL, Pacchierotti F, Russo A. The adverse outcome pathway (AOP) for chemical binding to tubulin in oocytes leading to aneuploid offspring. ENVIRONMENTAL AND MOLECULAR MUTAGENESIS 2016; 57:87-113. [PMID: 26581746 DOI: 10.1002/em.21986] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/27/2015] [Revised: 10/13/2015] [Accepted: 10/13/2015] [Indexed: 06/05/2023]
Abstract
The Organisation for Economic Co-operation and Development (OECD) has launched the Adverse Outcome Pathway (AOP) Programme to advance knowledge of pathways of toxicity and improve the use of mechanistic information in risk assessment. An AOP links a molecular initiating event (MIE) to an adverse outcome (AO) through intermediate key events (KE). Here, we present the scientific evidence in support of an AOP whereby chemicals that bind to tubulin cause microtubule depolymerization resulting in spindle disorganization followed by altered chromosome alignment and segregation and the generation of aneuploidy in female germ cells, ultimately leading to aneuploidy in the offspring. Aneuploidy, an abnormal number of chromosomes that is not an exact multiple of the haploid number, is a well-known cause of human disease and represents a major cause of infertility, pregnancy failure, and serious genetic disorders in the offspring. Among chemicals that induce aneuploidy in female germ cells, a large majority impairs microtubule dynamics and spindle function. Colchicine, a prototypical chemical that binds to tubulin and causes microtubule depolymerization, is used here to illustrate the AOP. This AOP is specific to female germ cells exposed during the periovulation period. Although the majority of the data come from rodent studies, the available evidence suggests that the MIE and KEs are conserved across species and would occur in human oocytes. The development of AOPs related to mutagenicity in germ cells is expected to aid the identification of potential hazards to germ cell genomic integrity and support regulatory efforts to protect population health.
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Affiliation(s)
- Francesco Marchetti
- Environmental Health Science and Research Bureau, Health Canada, Ottawa, Canada
| | - Alberto Massarotti
- Dipartimento Di Scienze Del Farmaco, Università Degli Studi Del Piemonte Orientale "A. Avogadro", Novara, Italy
| | - Carole L Yauk
- Environmental Health Science and Research Bureau, Health Canada, Ottawa, Canada
| | - Francesca Pacchierotti
- Division of Health Protection Technologies, Laboratory of Biosafety and Risk Assessment, ENEA CR Casaccia, Rome, Italy
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Abstract
SummaryMeiotic maturation of oocytes requires a variety of ATP-dependent reactions, such as germinal vesicle breakdown, spindle formation, and rearrangement of plasma membrane structure, which is required for fertilization. Mitochondria are accordingly expected be localized to subcellular sites of energy utilization. Although microtubule-dependent cellular traffic for mitochondria has been studied extensively in cultured neuronal (and some other somatic) cells, the molecular mechanism of their dynamics in mammalian oocytes at different stages of maturation remains obscure. The present work describes dynamic aspects of mitochondria in porcine oocytes at the germinal vesicle stage. After incubation of oocytes with MitoTracker Orange followed by centrifugation, mitochondria-enriched ooplasm was obtained using a glass needle and transferred into a recipient oocyte. The intracellular distribution of the fluorescent mitochondria was then observed over time using a laser scanning confocal microscopy equipped with an incubator. Kinetic analysis revealed that fluorescent mitochondria moved from central to subcortical areas of oocytes and were dispersed along plasma membranes. Such movement of mitochondria was inhibited by either cytochalasin B or cytochalasin D but not by colcemid, suggesting the involvement of microfilaments. This method of visualizing mitochondrial dynamics in live cells permits study of the pathophysiology of cytoskeleton-dependent intracellular traffic of mitochondria and associated energy metabolism during meiotic maturation of oocytes.
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Hou YJ, Zhu CC, Xu YX, Cui XS, Kim NH, Sun SC. Zearalenone exposure affects mouse oocyte meiotic maturation and granulosa cell proliferation. ENVIRONMENTAL TOXICOLOGY 2015; 30:1226-1233. [PMID: 24733567 DOI: 10.1002/tox.21995] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/16/2013] [Revised: 03/28/2014] [Accepted: 04/04/2014] [Indexed: 06/03/2023]
Abstract
Zearalenone (ZEN) is a metabolite of Fusarium and is a common contaminant of grains and foodstuffs. ZEN acts as a xenoestrogen and is considered to be cytotoxic, tissue toxic, and genotoxic, which causes abortions and stillbirths in humans and animals. Since estrogens affect oocyte maturation during meiosis, in this study we investigated the effects of ZEN on mouse oocyte meiotic maturation and granulosa cell proliferation. Our results showed that ZEN-treated oocyte maturation rates were decreased, which might be due to the disrupted cytoskeletons: (1) ZEN treatment resulted in significantly more oocytes with abnormal spindle morphologies; (2) actin filament expression and distribution were also disrupted after ZEN treatment, which was confirmed by the aberrant distribution of actin regulatory proteins. In addition, cortical granule-free domains (CGFDs) were disrupted after ZEN treatment, which indicated that ZEN may affect mouse oocyte fertilization capability. ZEN reduced mouse granulosa cell proliferation in a dose-dependent manner as determined by MTT assay and TUNEL apoptosis analysis, which may be another cause for the decreased oocyte maturation. Thus, our results demonstrated that exposure to zearalenone affected oocyte meiotic maturation and granulosa cell proliferation in mouse.
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Affiliation(s)
- Yan-Jun Hou
- College of Animal Science and Technology, Nanjing Agriculture University, Nanjing, 210095, China
| | - Cheng-Cheng Zhu
- College of Animal Science and Technology, Nanjing Agriculture University, Nanjing, 210095, China
| | - Yin-Xue Xu
- College of Animal Science and Technology, Nanjing Agriculture University, Nanjing, 210095, China
| | - Xiang-Shun Cui
- Department of Animal Sciences, Chungbuk National University, Cheongju, 361-763, Korea
| | - Nam-Hyung Kim
- Department of Animal Sciences, Chungbuk National University, Cheongju, 361-763, Korea
| | - Shao-Chen Sun
- College of Animal Science and Technology, Nanjing Agriculture University, Nanjing, 210095, China
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Kalo D, Roth Z. Effects of mono(2-ethylhexyl)phthalate on cytoplasmic maturation of oocytes--The bovine model. Reprod Toxicol 2015; 53:141-51. [PMID: 25900598 DOI: 10.1016/j.reprotox.2015.04.007] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2014] [Revised: 03/09/2015] [Accepted: 04/03/2015] [Indexed: 02/08/2023]
Abstract
Phthalates are known reproductive toxicants, but their intracellular disruptive effects on oocyte maturation competence are less known. We studied the potential risk associated with acute exposure of oocytes to mono(2-ethylhexyl)phthalate (MEHP). First, bovine oocytes were matured in vitro with or without 50 μM MEHP and examined for mitochondrial features associated with DNA fragmentation. MEHP increased reactive oxygen species levels and reduced the proportion of highly polarized mitochondria along with alterations in genes associated with mitochondrial oxidative phosphorylation (CYC1, MT-CO1 and ATP5B). In a second set of experiments, we associated the effects of MEHP on meiotic progression with those on cytoplasmic maturation. MEHP impaired reorganization of cytoplasmic organelles in matured oocytes reflected by reductions in category I mitochondria, type III cortical granules and class I endoplasmic reticulum. These alterations are associated with the previously reported reduced developmental competence of MEHP-treated bovine oocytes, and reveal the risk associated with acute exposure.
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Affiliation(s)
- D Kalo
- Department of Animal Sciences, Robert H. Smith Faculty of Agriculture, Food and Environment, and Center of Excellence in Agriculture and Environmental Health, the Hebrew University, Rehovot 76100, Israel
| | - Z Roth
- Department of Animal Sciences, Robert H. Smith Faculty of Agriculture, Food and Environment, and Center of Excellence in Agriculture and Environmental Health, the Hebrew University, Rehovot 76100, Israel.
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Behaviour of cytoplasmic organelles and cytoskeleton during oocyte maturation. Reprod Biomed Online 2013; 28:284-99. [PMID: 24444815 DOI: 10.1016/j.rbmo.2013.10.016] [Citation(s) in RCA: 97] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2013] [Revised: 10/16/2013] [Accepted: 10/17/2013] [Indexed: 11/21/2022]
Abstract
Assisted reproduction technology (ART) has become an attractive option for infertility treatment and holds tremendous promise. However, at present, there is still room for improvement in its success rates. Oocyte maturation is a process by which the oocyte becomes competent for fertilization and subsequent embryo development. To better understand the mechanism underlying oocyte maturation and for the future improvement of assisted reproduction technology, this review focuses on the complex processes of cytoplasmic organelles and the dynamic alterations of the cytoskeleton that occur during oocyte maturation. Ovarian stimulation and in-vitro maturation are the major techniques used in assisted reproduction technology and their influence on the organelles of oocytes is also discussed. Since the first birth by assisted reproduction treatment was achieved in 1978, numerous techniques involved in assisted reproduction have been developed and have become attractive options for infertility treatment. However, the unsatisfactory success rate remains as a main challenge. Oocyte maturation is a process by which the oocyte becomes competent for fertilization and subsequent embryo development. Oocyte maturation includes both nuclear and cytoplasmic maturation. Nuclear maturation primarily involves chromosomal segregation, which has been well studied, whereas cytoplasmic maturation involves a series of complicated processes, and there are still many parts of this process that remain controversial. Ovarian stimulation and in-vitro maturation (IVM) are the major techniques of assisted reproduction. The effect of ovarian stimulation or IVM on the behaviour of cell organelles of the oocyte has been postulated as the reason for the reduced developmental potential of in-vitro-produced embryos. To further understanding of the mechanism of oocyte maturation and future improvement of assisted reproduction treatment, the complex events of cytoplasmic organelles and the cytoskeleton that occur during oocyte maturation and the influence of ovarian stimulation and IVM on these organelles are described in this review.
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Abstract
Cortical granules are membrane bound organelles located in the cortex of unfertilized oocytes. Following fertilization, cortical granules undergo exocytosis to release their contents into the perivitelline space. This secretory process, which is calcium dependent and SNARE protein-mediated pathway, is known as the cortical reaction. After exocytosis, the released cortical granule proteins are responsible for blocking polyspermy by modifying the oocytes' extracellular matrices, such as the zona pellucida in mammals. Mammalian cortical granules range in size from 0.2 um to 0.6 um in diameter and different from most other regulatory secretory organelles in that they are not renewed once released. These granules are only synthesized in female germ cells and transform an egg upon sperm entry; therefore, this unique cellular structure has inherent interest for our understanding of the biology of fertilization. Cortical granules are long thought to be static and awaiting in the cortex of unfertilized oocytes to be stimulated undergoing exocytosis upon gamete fusion. Not till recently, the dynamic nature of cortical granules is appreciated and understood. The latest studies of mammalian cortical granules document that this organelle is not only biochemically heterogeneous, but also displays complex distribution during oocyte development. Interestingly, some cortical granules undergo exocytosis prior to fertilization; and a number of granule components function beyond the time of fertilization in regulating embryonic cleavage and preimplantation development, demonstrating their functional significance in fertilization as well as early embryonic development. The following review will present studies that investigate the biology of cortical granules and will also discuss new findings that uncover the dynamic aspect of this organelle in mammals.
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Affiliation(s)
- Min Liu
- Department of Life Science and Graduate Institute of Biotechnology, Private Chinese Culture University, Taipei, Republic of China.
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