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Sun Y, Zhu A. Correlation between the number of oocytes and the increase of polyspermy rate in IVF cycles. Gynecol Endocrinol 2023; 39:2217270. [PMID: 37247634 DOI: 10.1080/09513590.2023.2217270] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/12/2022] [Revised: 01/09/2023] [Accepted: 05/18/2023] [Indexed: 05/31/2023] Open
Abstract
Aims: To investigate the association between the number of oocytes and the polyspermy rate following in vitro fertilization (IVF) treatment. Materials and methods: 376 IVF cycles with gonadotropin-releasing hormone (GnRH) antagonist protocol in the reproductive center of our hospital were retrospectively included in the analysis, which were divided into five groups according to the number of oocytes retrieved. Group A (78 cases):1-5 oocytes, group B (118 cases): 6-10 oocytes, group C (94 cases): 11-15 oocytes, group D (55 cases): 16-20 oocytes, group E (31 cases): ≥21 oocytes. According to polyspermy rate, 376 IVF cycles were then divided into two groups. Normal level polyspermy group (170 cases): polyspermy rate<6%, and high level polyspermy group (206 cases): polyspermy rate ≥ 6%. The variables with p < .10 in univariate analysis were incorporated into the multiple logistic regression model to control the confounding, and the effect of the number of oocytes on the increase of polyspermy rate was analyzed. Results: Multiple logistic regression analysis showed that after adjustment for confounding factor, the increase risk of polyspermy rate in group B, C, D and E was 1.763, 3.804, 2.021 and 3.208 times of that in group A respectively (OR = 1.763, p = .085; OR = 3.804, p = .001; OR = 2.021, p = .158; OR = 3.208, p = .068, respectively). Conclusion: This result demonstrated that when the oocyte number is 15 or less, the more the oocyte number, the greater the increase risk of polyspermy rate. While, there appears to be little increase risk of polyspermy rate when the oocyte number is more than 15.
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Affiliation(s)
- Yating Sun
- Yuncheng Central Hospital, Yuncheng, Shanxi, China
| | - Aizhen Zhu
- Yuncheng Central Hospital, Yuncheng, Shanxi, China
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2
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Santella L, Limatola N, Chun JT. Cellular and molecular aspects of oocyte maturation and fertilization: a perspective from the actin cytoskeleton. ZOOLOGICAL LETTERS 2020; 6:5. [PMID: 32313685 PMCID: PMC7158055 DOI: 10.1186/s40851-020-00157-5] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/18/2019] [Accepted: 03/26/2020] [Indexed: 05/06/2023]
Abstract
ABSTRACT Much of the scientific knowledge on oocyte maturation, fertilization, and embryonic development has come from the experiments using gametes of marine organisms that reproduce by external fertilization. In particular, echinoderm eggs have enabled the study of structural and biochemical changes related to meiotic maturation and fertilization owing to the abundant availability of large and transparent oocytes and eggs. Thus, in vitro studies of oocyte maturation and sperm-induced egg activation in starfish are carried out under experimental conditions that resemble those occurring in nature. During the maturation process, immature oocytes of starfish are released from the prophase of the first meiotic division, and acquire the competence to be fertilized through a highly programmed sequence of morphological and physiological changes at the oocyte surface. In addition, the changes in the cortical and nuclear regions are essential for normal and monospermic fertilization. This review summarizes the current state of research on the cortical actin cytoskeleton in mediating structural and physiological changes during oocyte maturation and sperm and egg activation in starfish and sea urchin. The common denominator in these studies with echinoderms is that exquisite rearrangements of the egg cortical actin filaments play pivotal roles in gamete interactions, Ca2+ signaling, exocytosis of cortical granules, and control of monospermic fertilization. In this review, we also compare findings from studies using invertebrate eggs with what is known about the contributions made by the actin cytoskeleton in mammalian eggs. Since the cortical actin cytoskeleton affects microvillar morphology, movement, and positioning of organelles and vesicles, and the topography of the egg surface, these changes have impacts on the fertilization process, as has been suggested by recent morphological studies on starfish oocytes and eggs using scanning electron microscopy. Drawing the parallelism between vitelline layer of echinoderm eggs and the zona pellucida of mammalian eggs, we also discuss the importance of the egg surface in mediating monospermic fertilization. GRAPHICAL ABSTRACT
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Affiliation(s)
- Luigia Santella
- Department of Research Infrastructures for Marine Biological Resources, Stazione Zoologica Anton Dohrn, Villa Comunale, Napoli 80121, Italy
| | - Nunzia Limatola
- Department of Research Infrastructures for Marine Biological Resources, Stazione Zoologica Anton Dohrn, Villa Comunale, Napoli 80121, Italy
| | - Jong Tai Chun
- Department of Biology and Evolution of Marine Organisms, Stazione Zoologica Anton Dohrn, Villa Comunale, Napoli 80121, Italy
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3
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Abstract
Oocyte maturation is a process that occurs in the ovaries, where an immature oocyte resumes meiosis to attain competence for normal fertilization after ovulation/spawning. In starfish, the hormone 1-methyladenine binds to an unidentified receptor on the plasma membrane of oocytes, inducing a conformational change in the heterotrimeric GTP-binding protein α-subunit (Gα), so that the α-subunit binds GTP in exchange of GDP on the plasma membrane. The GTP-binding protein βγ-subunit (Gβγ) is released from Gα, and the released Gβγ activates phosphatidylinositol-3 kinase (PI3K), followed by the target of rapamycin kinase complex2 (TORC2) and 3-phosphoinositide-dependent protein kinase 1 (PDK1)-dependent phosphorylation of serum- and glucocorticoid-regulated kinase (SGK) of ovarian oocytes. Thereafter, SGK activates Na+/H+ exchanger (NHE) to increase the intracellular pH (pHi) from ~6.7 to ~6.9. Moreover, SGK phosphorylates Cdc25 and Myt1, thereby inducing the de-phosphorylation and activation of cyclin B–Cdk1, causing germinal vesicle breakdown (GVBD). Both pHi increase and GVBD are required for spindle assembly at metaphase I, followed by MI arrest at pHi 6.9 until spawning. Due to MI arrest or SGK-dependent pHi control, spawned oocytes can be fertilized normally
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Affiliation(s)
- Kazuyoshi Chiba
- Department of Biological Sciences, Ochanomizu University, Tokyo 112-8610, Japan
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4
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Hosoda E, Hiraoka D, Hirohashi N, Omi S, Kishimoto T, Chiba K. SGK regulates pH increase and cyclin B-Cdk1 activation to resume meiosis in starfish ovarian oocytes. J Cell Biol 2019; 218:3612-3629. [PMID: 31537709 PMCID: PMC6829648 DOI: 10.1083/jcb.201812133] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2018] [Revised: 07/19/2019] [Accepted: 08/15/2019] [Indexed: 12/31/2022] Open
Abstract
Tight regulation of intracellular pH (pHi) is essential for biological processes. Fully grown oocytes, having a large nucleus called the germinal vesicle, arrest at meiotic prophase I. Upon hormonal stimulus, oocytes resume meiosis to become fertilizable. At this time, the pHi increases via Na+/H+ exchanger activity, although the regulation and function of this change remain obscure. Here, we show that in starfish oocytes, serum- and glucocorticoid-regulated kinase (SGK) is activated via PI3K/TORC2/PDK1 signaling after hormonal stimulus and that SGK is required for this pHi increase and cyclin B-Cdk1 activation. When we clamped the pHi at 6.7, corresponding to the pHi of unstimulated ovarian oocytes, hormonal stimulation induced cyclin B-Cdk1 activation; thereafter, oocytes failed in actin-dependent chromosome transport and spindle assembly after germinal vesicle breakdown. Thus, this SGK-dependent pHi increase is likely a prerequisite for these events in ovarian oocytes. We propose a model that SGK drives meiotic resumption via concomitant regulation of the pHi and cell cycle machinery.
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Affiliation(s)
- Enako Hosoda
- Department of Biological Sciences, Ochanomizu University, Tokyo, Japan
| | - Daisaku Hiraoka
- Science and Education Center, Ochanomizu University, Tokyo, Japan
| | | | - Saki Omi
- Department of Biological Sciences, Ochanomizu University, Tokyo, Japan
| | - Takeo Kishimoto
- Science and Education Center, Ochanomizu University, Tokyo, Japan
| | - Kazuyoshi Chiba
- Department of Biological Sciences, Ochanomizu University, Tokyo, Japan
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5
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Kim KS, Kim TH, Kim MA, Lee JS, Sohn YC. Expression profile and reproductive regulation of APGWamide in Pacific abalone (Haliotis discus hannai). Comp Biochem Physiol A Mol Integr Physiol 2018; 222:26-35. [PMID: 29679684 DOI: 10.1016/j.cbpa.2018.04.005] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2018] [Revised: 04/03/2018] [Accepted: 04/11/2018] [Indexed: 12/30/2022]
Abstract
Neuropeptides in the central nervous system regulate reproductive activities in vertebrates. Ala-Pro-Gly-Trp-NH2 (APGWamide), a neuromediator expressed in the neural ganglia of mollusks, controls sexual maturation and reproduction. To clarify the role of APGWamide in sexual behavior regulation and gamete cell maturation in mollusks, we cloned the cDNA of APGWamide precursor (Hdh-APGWamide) and examined the spatiotemporal expression of the transcript in the Pacific abalone Haliotis discus hannai. The 222-amino acid sequence of the precursor deduced from the cDNA sequence showed typical features of gastropod APGWamide precursors. Phylogenetic analysis revealed that Hdh-APGWamide is classified with other gastropod APGWamide precursors, which form a separate branch from those of the bivalves. Hdh-APGWamide mRNA was highly expressed in the neural ganglia in both sexes. In females, the three ganglia (pleuro-pedal ganglion, PPG; branchial ganglion, and cerebral ganglion) showed similar expression in immature and mature animals, whereas in males, the level in the PPG only was higher at maturity (P < 0.05). In vivo injection of APGWamide or 5-hydroxytryptamine (10-3 M) increased the frequency of spawning and the number of released sperm cells by mature males (P < 0.05), while concentrations above 10-7 M enhanced germinal vesicle breakdown in fully developed cultured oocytes (P < 0.05). Thus, the phylogenetic branch of the APGWamide precursor gene in Haliotidae was separate from the other branches under the phylum Mollusca, and this gene exhibited ganglion-specific expression, indicating that it may induce final maturation and spawning in both sexes of Haliotis spp.
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Affiliation(s)
- Kyeong Seop Kim
- Department of Marine Molecular Biosciences, Gangneung-Wonju National University, 7 Jukheon-gil, Gangneung, Gangwon 25457, Republic of Korea
| | - Tae Ha Kim
- Department of Marine Molecular Biosciences, Gangneung-Wonju National University, 7 Jukheon-gil, Gangneung, Gangwon 25457, Republic of Korea
| | - Mi Ae Kim
- East Coast Life Sciences Institute, Gangneung-Wonju National University, 7 Jukheon-gil, Gangneung, Gangwon 25457, Republic of Korea
| | - Jung Sick Lee
- Department of Aqualife Medicine, Chonnam National University, Yeosu 59626, Republic of Korea
| | - Young Chang Sohn
- Department of Marine Molecular Biosciences, Gangneung-Wonju National University, 7 Jukheon-gil, Gangneung, Gangwon 25457, Republic of Korea.
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6
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Abstract
The most fundamental unresolved issue of fertilization is to define how the sperm activates the egg to begin embryo development. Egg activation at fertilization in all species thus far examined is caused by some form of transient increase in the cytoplasmic free Ca2+ concentration. What has not been clear, however, is precisely how the sperm triggers the large changes in Ca2+ observed within the egg cytoplasm. Here, we review the studies indicating that the fertilizing sperm stimulates a cytosolic Ca2+ increase in the egg specifically by delivering a soluble factor that diffuses into the cytosolic space of the egg upon gamete membrane fusion. Evidence is primarily considered in species of eggs where the sperm has been shown to elicit a cytosolic Ca2+ increase by initiating Ca2+ release from intracellular Ca2+ stores. We suggest that our best understanding of these signaling events is in mammals, where the sperm triggers a prolonged series of intracellular Ca2+ oscillations. The strongest empirical studies to date suggest that mammalian sperm-triggered Ca2+ oscillations are caused by the introduction of a sperm-specific protein, called phospholipase C-zeta (PLCζ) that generates inositol trisphosphate within the egg. We will discuss the role and mechanism of action of PLCζ in detail at a molecular and cellular level. We will also consider some of the evidence that a soluble sperm protein might be involved in egg activation in nonmammalian species.
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Affiliation(s)
- Karl Swann
- College of Biomedical and Life Sciences, School of Medicine, Cardiff University, Cardiff, United Kingdom
| | - F. Anthony Lai
- College of Biomedical and Life Sciences, School of Medicine, Cardiff University, Cardiff, United Kingdom
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7
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Matthews LM, Evans JP. α-endosulfine (ENSA) regulates exit from prophase I arrest in mouse oocytes. Cell Cycle 2014; 13:1639-49. [PMID: 24675883 DOI: 10.4161/cc.28606] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Mammalian oocytes in ovarian follicles are arrested in meiosis at prophase I. This arrest is maintained until ovulation, upon which the oocyte exits from this arrest, progresses through meiosis I and to metaphase of meiosis II. The progression from prophase I to metaphase II, known as meiotic maturation, is mediated by signals that coordinate these transitions in the life of the oocyte. ENSA (α-endosulfine) and ARPP19 (cAMP-regulated phosphoprotein-19) have emerged as regulators of M-phase, with function in inhibition of protein phosphatase 2A (PP2A) activity. Inhibition of PP2A maintains the phosphorylated state of CDK1 substrates, thus allowing progression into and/or maintenance of an M-phase state. We show here ENSA in mouse oocytes plays a key role in the progression from prophase I arrest into M-phase of meiosis I. The majority of ENSA-deficient oocytes fail to exit from prophase I arrest. This function of ENSA in oocytes is dependent on PP2A, and specifically on the regulatory subunit PPP2R2D (also known as B55δ). Treatment of ENSA-deficient oocytes with Okadaic acid to inhibit PP2A rescues the defect in meiotic progression, with Okadaic acid-treated, ENSA-deficient oocytes being able to exit from prophase I arrest. Similarly, oocytes deficient in both ENSA and PPP2R2D are able to exit from prophase I arrest to an extent similar to wild-type oocytes. These data are evidence of a role for ENSA in regulating meiotic maturation in mammalian oocytes, and also have potential relevance to human oocyte biology, as mouse and human have genes encoding both Arpp19 and Ensa.
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Affiliation(s)
- Lauren M Matthews
- Department of Biochemistry and Molecular Biology; Bloomberg School of Public Health; Johns Hopkins University; Baltimore, MD USA
| | - Janice P Evans
- Department of Biochemistry and Molecular Biology; Bloomberg School of Public Health; Johns Hopkins University; Baltimore, MD USA
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8
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Kempisty B, Ziółkowska A, Piotrowska H, Antosik P, Bukowska D, Zawierucha P, Jaśkowski J, Brüssow KP, Nowicki M, Zabel M. Expression and cellular distribution of cyclin-dependent kinase 4 (Cdk4) and connexin 43 (Cx43) in porcine oocytes before and after in vitro maturation. Acta Vet Hung 2014; 62:84-95. [PMID: 24334079 DOI: 10.1556/avet.2013.039] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
It is recognised that connexin 43 (Cx43) and cyclin-dependent kinase 4 (Cdk4) are involved in the cumulus cell-oocyte communication via gap junctions and the control of cell cycle progress. However, little is known about their mRNA expression pattern and encoded proteins distribution in porcine oocytes during in vitro maturation (IVM). Cumulus-oocyte complexes (COCs) were collected from 31 puberal crossbred Landrace gilts and analysed for their Cdk4 and Cx43 mRNA expression using RQ-PCR and for the respective protein expression by confocal microscopic observations. An increased Cdk4 and Cx43 mRNA expression was found in oocytes after IVM (P < 0.001 and P < 0.05, respectively). Confocal microscopic observations revealed a significant increase of Cdk4 protein expression in the cytoplasm of oocytes during the maturation process. The localisation of Cx43 changed from zona pellucida before to cytoplasm of oocytes after IVM. It is supposed that the increased expression of Cdk4 and Cx43 mRNA in oocytes after IVM is linked with the accumulation of a large amount of templates during the process of oocyte maturation. The translocation especially of Cx43 from the zona pellucida into the cytoplasm may be associated with a decrease in gap junction activity in fully grown porcine oocytes. Both Cdk4 and Cx43 can be used as 'checkpoints' of oocyte maturation.
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Affiliation(s)
| | - Agnieszka Ziółkowska
- 1 Poznań University of Medical Sciences Department of Histology and Embryology Poznań Poland
| | - Hanna Piotrowska
- 3 Poznań University of Medical Sciences Department of Toxicology 30 Dojazd St. 60-631 Poznań Poland
| | - Paweł Antosik
- 4 Poznań University of Life Sciences Department of Veterinary Poznań Poland
| | - Dorota Bukowska
- 4 Poznań University of Life Sciences Department of Veterinary Poznań Poland
| | | | - Jędrzej Jaśkowski
- 4 Poznań University of Life Sciences Department of Veterinary Poznań Poland
| | - Klaus-Peter Brüssow
- 5 Leibniz Institute for Farm Animal Biology Department of Reproductive Biology Dummerstorf Germany
| | - Michał Nowicki
- 1 Poznań University of Medical Sciences Department of Histology and Embryology Poznań Poland
| | - Maciej Zabel
- 1 Poznań University of Medical Sciences Department of Histology and Embryology Poznań Poland
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Moriwaki K, Nakagawa T, Nakaya F, Hirohashi N, Chiba K. Arrest at metaphase of meiosis I in starfish oocytes in the ovary is maintained by high CO2 and low O2 concentrations in extracellular fluid. Zoolog Sci 2014; 30:975-84. [PMID: 24199863 DOI: 10.2108/zsj.30.975] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
During the spawning process in starfish, oocytes are arrested at metaphase of meiosis I (MI) within the ovary, and reinitiate meiosis only after they have been released into the seawater. However, this arrest does not occur if the ovary is removed from the animal. As the pH of the coelomic fluid is buffered by CO2/H(+)/HCO3(-), we investigated the involvement of gas concentrations in MI arrest. In vivo, the CO2 level in the coelomic fluid was high (∼1.5% vs. 0.04% in air) and the O2 level was low (0.1-1.0% vs. ∼20% in air). When these gas conditions were reproduced in isolated coelomic fluid or seawater, ovarian oocytes arrested at MI, just as in vivo. Isolated oocytes from the ovary required the similar high CO2 and low O2 level to remain arrested in MI and had an intracellular pH of ∼6.9. Intracellular pH increased to ∼7.3 when oocytes were transferred to seawater equilibrated with air, a condition that mimics that of spawning. We used ammonium acetate to clamp intracellular pH at different levels and found that MI arrest occurred when intracellular pH was ∼6.9. Our results support the idea that high CO2 and low O2 in the ovarian environment lead to low intracellular pH and MI arrest, while spawning into the seawater with low CO2 and high O2 results in high intracellular pH and release from MI arrest. The biological significance of MI arrest is that oocytes are spawned into seawater at the optimal physiological state of MI when the least polyspermy occurs.
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Affiliation(s)
- Kei Moriwaki
- Department of Biological Sciences, Ochanomizu University, 2-1-1 Ohtsuka, Bunkyo-ku, Tokyo 112-8610, Japan
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Kryzak CA, Moraine MM, Kyle DD, Lee HJ, Cubeñas-Potts C, Robinson DN, Evans JP. Prophase I mouse oocytes are deficient in the ability to respond to fertilization by decreasing membrane receptivity to sperm and establishing a membrane block to polyspermy. Biol Reprod 2013; 89:44. [PMID: 23863404 DOI: 10.1095/biolreprod.113.110221] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Abstract
Changes occurring as the prophase I oocyte matures to metaphase II are critical for the acquisition of competence for normal egg activation and early embryogenesis. A prophase I oocyte cannot respond to a fertilizing sperm as a metaphase II egg does, including the ability to prevent polyspermic fertilization. Studies here demonstrate that the competence for the membrane block to polyspermy is deficient in prophase I mouse oocytes. In vitro fertilization experiments using identical insemination conditions result in monospermy in 87% of zona pellucida (ZP)-free metaphase II eggs, while 92% of ZP-free prophase I oocytes have four or more fused sperm. The membrane block is associated with a postfertilization reduction in the capacity to support sperm binding, but this reduction in sperm-binding capacity is both less robust and slower to develop in fertilized prophase I oocytes. Fertilization of oocytes is dependent on the tetraspanin CD9, but little to no release of CD9 from the oocyte membrane is detected, suggesting that release of CD9-containing vesicles is not essential for fertilization. The deficiency in membrane block establishment in prophase I oocytes correlates with abnormalities in two postfertilization cytoskeletal changes: sperm-induced cortical remodeling that results in fertilization cone formation and a postfertilization increase in effective cortical tension. These data indicate that cortical maturation is a component of cytoplasmic maturation during the oocyte-to-egg transition and that the egg cortex has to be appropriately primed and tuned to be responsive to a fertilizing sperm.
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Affiliation(s)
- Cassie A Kryzak
- Department of Biochemistry and Molecular Biology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, Maryland 21205, USA
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Ramos I, Wessel GM. Calcium pathway machinery at fertilization in echinoderms. Cell Calcium 2012; 53:16-23. [PMID: 23218671 DOI: 10.1016/j.ceca.2012.11.011] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2012] [Revised: 11/07/2012] [Accepted: 11/09/2012] [Indexed: 01/01/2023]
Abstract
Calcium signaling in cells directs diverse physiological processes. The calcium waves triggered by fertilization is a highly conserved calcium signaling event essential for egg activation, and has been documented in every egg tested. This activity is one of the few highly conserved events of egg activation through the course of evolution. Echinoderm eggs, as well as many other cell types, have three main intracellular Ca(2+) mobilizing messengers - IP3, cADPR and NAADP. Both cADPR and NAADP were identified as Ca(2+) mobilizing messengers using the sea urchin egg homogenate, and this experimental system, along with the intact urchin and starfish oocyte/egg, continues to be a vital tool for investigating the mechanism of action of calcium signals. While many of the major regulatory steps of the IP3 pathway are well resolved, both cADPR and NAADP remain understudied in terms of our understanding of the fundamental process of egg activation at fertilization. Recently, NAADP has been shown to trigger Ca(2+) release from acidic vesicles, separately from the ER, and a new class of calcium channels, the two-pore channels (TPCs), was identified as the likely targets for this messenger. Moreover, it was found that both cADPR and NAADP can be synthesized by the same family of enzymes, the ADP-rybosyl cyclases (ARCs). In this context of increasing amount of information, the potential coupling and functional roles of different messengers, intracellular stores and channels in the formation of the fertilization calcium wave in echinoderms will be critically evaluated.
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Affiliation(s)
- Isabela Ramos
- Department of Molecular Biology, Cellular Biology, and Biochemistry, Brown University, Providence, RI 02912, USA
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