1
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Watabe M, Hiraiwa A, Sakai M, Ueno T, Ueno S, Nakajima K, Yaoita Y, Iwao Y. Sperm MMP-2 is indispensable for fast electrical block to polyspermy at fertilization in Xenopus tropicalis. Mol Reprod Dev 2021; 88:744-757. [PMID: 34618381 DOI: 10.1002/mrd.23540] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2021] [Accepted: 09/24/2021] [Indexed: 01/10/2023]
Abstract
Sperm matrix metalloproteinase-2 (MMP-2) is necessary for frog fertilization. Monospermy is ensured by a fast, electrical block to polyspermy mediated by a positive fertilization potential. To determine the role of the MMP-2 hemopexin domain (HPX) in a fast block to polyspermy during fertilization of the frog, Xenopus tropicalis, we prepared mutant frogs deficient in mmp2 gene using the transcription activator-like effector nuclease method. mmp2 ΔHPX (-/-) sperm without MMP-2 protein were able to fertilize wild-type (WT; +/+) eggs. However, polyspermy occurred in some eggs. The mutant sperm generated a normal fertilization potential amounting to 10 mV, and were able to fertilize eggs at 10 mV, at which WT sperm never fertilized. Sensitivity during voltage-dependent fertilization decreased in mutant sperm. This study demonstrates for the first time that the genetic alteration of the MMP-2 molecule in sperm causes polyspermy during fertilization of a monospermic species. Our findings provide reliable evidence that sperm MMP-2 is indispensable for the fast, electrical block to polyspermy during Xenopus fertilization.
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Affiliation(s)
- Mami Watabe
- Laboratory of Reproductive Developmental Biology and Developmental Cell Biology, Graduate School of Sciences and Technology for Innovation, Yamaguchi University, Yamaguchi, Japan
| | - Azusa Hiraiwa
- Laboratory of Reproductive Developmental Biology and Developmental Cell Biology, Graduate School of Sciences and Technology for Innovation, Yamaguchi University, Yamaguchi, Japan
| | - Mami Sakai
- Laboratory of Reproductive Developmental Biology and Developmental Cell Biology, Graduate School of Sciences and Technology for Innovation, Yamaguchi University, Yamaguchi, Japan
| | - Tomoyo Ueno
- Laboratory of Reproductive Developmental Biology and Developmental Cell Biology, Graduate School of Sciences and Technology for Innovation, Yamaguchi University, Yamaguchi, Japan
| | - Shuichi Ueno
- Laboratory of Reproductive Developmental Biology and Developmental Cell Biology, Graduate School of Sciences and Technology for Innovation, Yamaguchi University, Yamaguchi, Japan
| | - Keisuke Nakajima
- Division of Embryology, Amphibian Research Center, Hiroshima University, Higashihiroshima, Japan
| | - Yoshio Yaoita
- Division of Embryology, Amphibian Research Center, Hiroshima University, Higashihiroshima, Japan
| | - Yasuhiro Iwao
- Laboratory of Reproductive Developmental Biology and Developmental Cell Biology, Graduate School of Sciences and Technology for Innovation, Yamaguchi University, Yamaguchi, Japan
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2
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Hughes MP, Kruchek EJ, Beale AD, Kitcatt SJ, Qureshi S, Trott ZP, Charbonnel O, Agbaje PA, Henslee EA, Dorey RA, Lewis R, Labeed FH. V m-related extracellular potentials observed in red blood cells. Sci Rep 2021; 11:19446. [PMID: 34593849 PMCID: PMC8484267 DOI: 10.1038/s41598-021-98102-9] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2021] [Accepted: 08/25/2021] [Indexed: 11/16/2022] Open
Abstract
Even in nonexcitable cells, the membrane potential Vm is fundamental to cell function, with roles from ion channel regulation, development, to cancer metastasis. Vm arises from transmembrane ion concentration gradients; standard models assume homogeneous extracellular and intracellular ion concentrations, and that Vm only exists across the cell membrane and has no significance beyond it. Using red blood cells, we show that this is incorrect, or at least incomplete; Vm is detectable beyond the cell surface, and modulating Vm produces quantifiable and consistent changes in extracellular potential. Evidence strongly suggests this is due to capacitive coupling between Vm and the electrical double layer, rather than molecular transporters. We show that modulating Vm changes the extracellular ion composition, mimicking the behaviour if voltage-gated ion channels in non-excitable channels. We also observed Vm-synchronised circadian rhythms in extracellular potential, with significant implications for cell–cell interactions and cardiovascular disease.
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Affiliation(s)
- Michael Pycraft Hughes
- Centre for Biomedical Engineering, University of Surrey, Guildford, Surrey, GU2 7XH, UK.
| | - Emily J Kruchek
- Centre for Biomedical Engineering, University of Surrey, Guildford, Surrey, GU2 7XH, UK
| | - Andrew D Beale
- Centre for Biomedical Engineering, University of Surrey, Guildford, Surrey, GU2 7XH, UK.,MRC Laboratory for Molecular Biology, Francis Crick Avenue, Cambridge, CB2 0QH, UK
| | - Stephen J Kitcatt
- Centre for Biomedical Engineering, University of Surrey, Guildford, Surrey, GU2 7XH, UK
| | - Sara Qureshi
- Centre for Biomedical Engineering, University of Surrey, Guildford, Surrey, GU2 7XH, UK
| | - Zachary P Trott
- Centre for Biomedical Engineering, University of Surrey, Guildford, Surrey, GU2 7XH, UK
| | - Oriane Charbonnel
- Centre for Biomedical Engineering, University of Surrey, Guildford, Surrey, GU2 7XH, UK.,School of Engineering, École Centrale de Lyon, 36 Avenue Guy de Collongue, 69134, Écully, France
| | - Paul A Agbaje
- Centre for Biomedical Engineering, University of Surrey, Guildford, Surrey, GU2 7XH, UK
| | - Erin A Henslee
- Centre for Biomedical Engineering, University of Surrey, Guildford, Surrey, GU2 7XH, UK.,Department of Engineering, Wake Forest University, 55 Vine St, Wake Downtown, Winston-Salem, NC, 27109, USA
| | - Robert A Dorey
- Centre for Biomedical Engineering, University of Surrey, Guildford, Surrey, GU2 7XH, UK
| | - Rebecca Lewis
- School of Veterinary Medicine, University of Surrey, Guildford, Surrey, GU2 7XH, UK
| | - Fatima H Labeed
- Centre for Biomedical Engineering, University of Surrey, Guildford, Surrey, GU2 7XH, UK
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3
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Iwao Y, Kimoto C, Fujimoto A, Suda A, Hara Y. Physiological polyspermy: Selection of a sperm nucleus for the development of diploid genomes in amphibians. Mol Reprod Dev 2020; 87:358-369. [DOI: 10.1002/mrd.23235] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2019] [Accepted: 06/23/2019] [Indexed: 01/04/2023]
Affiliation(s)
- Yasuhiro Iwao
- Laboratory of Reproductive Developmental Biology, Division of Earth Sciences, Biology, and Chemistry, Graduate School of Sciences and Technology for InnovationYamaguchi University Yamaguchi Yamaguchi Japan
| | - Chihiro Kimoto
- Laboratory of Reproductive Developmental Biology, Division of Earth Sciences, Biology, and Chemistry, Graduate School of Sciences and Technology for InnovationYamaguchi University Yamaguchi Yamaguchi Japan
| | - Ayaka Fujimoto
- Laboratory of Reproductive Developmental Biology, Division of Earth Sciences, Biology, and Chemistry, Graduate School of Sciences and Technology for InnovationYamaguchi University Yamaguchi Yamaguchi Japan
| | - Asuka Suda
- Laboratory of Reproductive Developmental Biology, Division of Earth Sciences, Biology, and Chemistry, Graduate School of Sciences and Technology for InnovationYamaguchi University Yamaguchi Yamaguchi Japan
| | - Yuki Hara
- Laboratory of Evolutionary Cell Biology, Department of Biology and Chemistry, Faculty of ScienceYamaguchi University Yamaguchi Yamaguchi Japan
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4
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Watabe M, Izaki K, Fujino S, Maruyama M, Kojima C, Hiraiwa A, Ueno S, Iwao Y. The electrical block to polyspermy induced by an intracellular Ca
2+
increase at fertilization of the clawed frogs,
Xenopus laevis
and
Xenopus tropicalis. Mol Reprod Dev 2019; 86:387-403. [DOI: 10.1002/mrd.23115] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2018] [Revised: 12/26/2018] [Accepted: 01/09/2019] [Indexed: 11/08/2022]
Affiliation(s)
- Mami Watabe
- Laboratory of Reproductive Developmental BiologyGraduate School of Sciences and Technology for Innovation, Yamaguchi University Yamaguchi Japan
| | - Kenta Izaki
- Laboratory of Reproductive Developmental BiologyGraduate School of Sciences and Technology for Innovation, Yamaguchi University Yamaguchi Japan
| | - Shohei Fujino
- Laboratory of Reproductive Developmental BiologyGraduate School of Sciences and Technology for Innovation, Yamaguchi University Yamaguchi Japan
| | - Mei Maruyama
- Laboratory of Reproductive Developmental BiologyGraduate School of Sciences and Technology for Innovation, Yamaguchi University Yamaguchi Japan
| | - Chiho Kojima
- Laboratory of Reproductive Developmental BiologyGraduate School of Sciences and Technology for Innovation, Yamaguchi University Yamaguchi Japan
| | - Azusa Hiraiwa
- Laboratory of Reproductive Developmental BiologyGraduate School of Sciences and Technology for Innovation, Yamaguchi University Yamaguchi Japan
| | - Shuichi Ueno
- Laboratory of Reproductive Developmental BiologyGraduate School of Sciences and Technology for Innovation, Yamaguchi University Yamaguchi Japan
| | - Yasuhiro Iwao
- Laboratory of Reproductive Developmental BiologyGraduate School of Sciences and Technology for Innovation, Yamaguchi University Yamaguchi Japan
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5
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Abstract
Jaffe underscores new research that identifies key roles for IP3 and TMEM16a in the fast block to polyspermy.
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Affiliation(s)
- Laurinda A Jaffe
- Department of Cell Biology, University of Connecticut Health Center, Farmington, CT
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6
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Universality and Diversity of a Fast, Electrical Block to Polyspermy During Fertilization in Animals. DIVERSITY AND COMMONALITY IN ANIMALS 2018. [DOI: 10.1007/978-4-431-56609-0_24] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
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7
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Fertilization 2: Polyspermic Fertilization. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2017; 1001:105-123. [DOI: 10.1007/978-981-10-3975-1_7] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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8
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9
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Iwao Y, Shiga K, Shiroshita A, Yoshikawa T, Sakiie M, Ueno T, Ueno S, Ijiri TW, Sato KI. The need of MMP-2 on the sperm surface for Xenopus fertilization: Its role in a fast electrical block to polyspermy. Mech Dev 2014; 134:80-95. [DOI: 10.1016/j.mod.2014.09.005] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2014] [Revised: 09/22/2014] [Accepted: 09/24/2014] [Indexed: 01/31/2023]
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10
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Mutua J, Jinno Y, Sakata S, Okochi Y, Ueno S, Tsutsui H, Kawai T, Iwao Y, Okamura Y. Functional diversity of voltage-sensing phosphatases in two urodele amphibians. Physiol Rep 2014; 2:e12061. [PMID: 25347851 PMCID: PMC4187576 DOI: 10.14814/phy2.12061] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Voltage-sensing phosphatases (VSPs) share the molecular architecture of the voltage sensor domain (VSD) with voltage-gated ion channels and the phosphoinositide phosphatase region with the phosphatase and tensin homolog (PTEN), respectively. VSPs enzymatic activities are regulated by the motions of VSD upon depolarization. The physiological role of these proteins has remained elusive, and insights may be gained by investigating biological variations in different animal species. Urodele amphibians are vertebrates with potent activities of regeneration and also show diverse mechanisms of polyspermy prevention. We cloned cDNAs of VSPs from the testes of two urodeles; Hynobius nebulosus and Cynops pyrrhogaster, and compared their expression and voltage-dependent activation. Their molecular architecture is highly conserved in both Hynobius VSP (Hn-VSP) and Cynops VSP (Cp-VSP), including the positively-charged arginine residues in the S4 segment of the VSD and the enzymatic active site for substrate binding, yet the C-terminal C2 domain of Hn-VSP is significantly shorter than that of Cp-VSP and other VSP orthologs. RT-PCR analysis showed that gene expression pattern was distinct between two VSPs. The voltage sensor motions and voltage-dependent phosphatase activities were investigated electrophysiologically by expression in Xenopus oocytes. Both VSPs showed "sensing" currents, indicating that their voltage sensor domains are functional. The phosphatase activity of Cp-VSP was found to be voltage dependent, as shown by its ability to regulate the conductance of coexpressed GIRK2 channels, but Hn-VSP lacked such phosphatase activity due to the truncation of its C2 domain.
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Affiliation(s)
- Joshua Mutua
- Graduate School of Frontier Biosciences, Osaka University, Suita, Osaka, Japan
| | - Yuka Jinno
- Laboratory of Integrative Physiology, Department of Physiology, Graduate School of Medicine, Osaka University, Suita, Osaka, Japan
| | - Souhei Sakata
- Laboratory of Integrative Physiology, Department of Physiology, Graduate School of Medicine, Osaka University, Suita, Osaka, Japan
| | - Yoshifumi Okochi
- Laboratory of Integrative Physiology, Department of Physiology, Graduate School of Medicine, Osaka University, Suita, Osaka, Japan
| | - Shuichi Ueno
- Laboratory of Molecular Developmental Biology, Department of Applied Molecular Biosciences, Graduate School of Medicine, Yamaguchi University, Yamaguchi, Japan
| | - Hidekazu Tsutsui
- Laboratory of Integrative Physiology, Department of Physiology, Graduate School of Medicine, Osaka University, Suita, Osaka, Japan
| | - Takafumi Kawai
- Laboratory of Integrative Physiology, Department of Physiology, Graduate School of Medicine, Osaka University, Suita, Osaka, Japan
| | - Yasuhiro Iwao
- Laboratory of Molecular Developmental Biology, Department of Applied Molecular Biosciences, Graduate School of Medicine, Yamaguchi University, Yamaguchi, Japan
| | - Yasushi Okamura
- Graduate School of Frontier Biosciences, Osaka University, Suita, Osaka, Japan Laboratory of Integrative Physiology, Department of Physiology, Graduate School of Medicine, Osaka University, Suita, Osaka, Japan
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11
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Abstract
Fertilization is indispensable not only for restoring diploid genomes but also for the initiation of early embryonic cell cycles in sexual reproduction. While most animals exhibit monospermy, which is ensured by polyspermy blocks to prevent the entry of extra sperm into the egg at fertilization, several animals exhibit physiological polyspermy, in which the entry of several sperm is permitted but only one sperm nucleus participates in the formation of a zygote nucleus. Polyspermy requires that the sperm transmit the egg activation signal more slowly, thus allowing the egg to accept several sperm. An increase in intracellular Ca(2+) concentration induced by the fertilizing sperm is both necessary and sufficient for egg activation in polyspermy. Multiple small Ca(2+) waves induced by several fertilizing sperm result in a long-lasting Ca(2+) rise, which is a characteristic of polyspermic amphibian eggs. We introduced a novel soluble sperm factor for egg activation, sperm-specific citrate synthase, into polyspermic newt eggs to cause Ca(2+) waves. Citrate synthase may perform dual functions: as an enzyme in mitochondria and as a Ca(2+)-inducing factor in egg cytoplasm. We also discuss the close relationship between the mode of fertilization and the Ca(2+) rise at egg activation and consider changes in this process through evolution in vertebrates.
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Affiliation(s)
- Yasuhiro Iwao
- Laboratory of Molecular Developmental Biology, Department of Applied Molecular Biosciences, Graduate School of Medicine, Yamaguchi University, 753-8512 Yamaguchi, Japan.
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12
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Ratzan WJ, Evsikov AV, Okamura Y, Jaffe LA. Voltage sensitive phosphoinositide phosphatases of Xenopus: their tissue distribution and voltage dependence. J Cell Physiol 2011; 226:2740-6. [PMID: 21618529 PMCID: PMC3181042 DOI: 10.1002/jcp.22854] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Voltage-sensitive phosphatases (VSPs) are unique proteins in which membrane potential controls enzyme activity. They are comprised of the voltage sensor domain of an ion channel coupled to a lipid phosphatase specific for phosphoinositides, and for ascidian and zebrafish VSPs, the phosphatase activity has been found to be activated by membrane depolarization. The physiological functions of these proteins are unknown, but their expression in testis and embryos suggests a role in fertilization or development. Here we investigate the expression pattern and voltage dependence of VSPs in two frog species, Xenopus laevis and Xenopus tropicalis, that are well suited for experimental studies of these possible functions. X. laevis has two VSP genes (Xl-VSP1 and Xl-VSP2), whereas X. tropicalis has only one gene (Xt-VSP). The highest expression of these genes was observed in testis, ovary, liver, and kidney. Our results show that while Xl-VSP2 activates only at positive membrane potentials outside of the physiological range, Xl-VSP1 and Xt-VSP phosphatase activity is regulated in the voltage range that regulates sperm-egg fusion at fertilization.
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Affiliation(s)
- William J. Ratzan
- Department of Cell Biology, University of Connecticut Health Center, Farmington, CT, USA
| | | | | | - Laurinda A. Jaffe
- Department of Cell Biology, University of Connecticut Health Center, Farmington, CT, USA
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13
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The Ca2+ increase by the sperm factor in physiologically polyspermic newt fertilization: its signaling mechanism in egg cytoplasm and the species-specificity. Dev Biol 2011; 351:266-76. [PMID: 21237143 DOI: 10.1016/j.ydbio.2011.01.003] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2010] [Revised: 12/27/2010] [Accepted: 01/05/2011] [Indexed: 11/22/2022]
Abstract
The newt, Cynops pyrrhogaster, exhibits physiological polyspermic fertilization, in which several sperm enter an egg before egg activation. An intracellular Ca(2+) increase occurs as a Ca(2+) wave at each sperm entry site in the polyspermic egg. Some Ca(2+) waves are preceded by a transient spike-like Ca(2+) increase, probably caused by a tryptic protease in the sperm acrosome at the contact of sperm on the egg surface. The following Ca(2+) wave was induced by a sperm factor derived from sperm cytoplasm after sperm-egg membrane fusion. The Ca(2+) increase in the isolated, cell-free cytoplasm indicates that the endoplasmic reticulum is the major Ca(2+) store for the Ca(2+) wave. We previously demonstrated that citrate synthase in the sperm cytoplasm is a major sperm factor for egg activation in newt fertilization. In the present study, we found that the activation by the sperm factor as well as by fertilizing sperm was prevented by an inhibitor of citrate synthase, palmitoyl CoA, and that an injection of acetyl-CoA or oxaloacetate caused egg activation, indicating that the citrate synthase activity is necessary for egg activation at fertilization. In the frog, Xenopus laevis, which exhibits monospermic fertilization, we were unable to activate the eggs with either the homologous sperm extract or the Cynops sperm extract, indicating that Xenopus sperm lack the sperm factor for egg activation and that their eggs are insensitive to the newt sperm factor. The mechanism of egg activation in the monospermy of frog eggs is quite different from that in the physiological polyspermy of newt eggs.
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14
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Markosyan RM, Cohen FS. Negative potentials across biological membranes promote fusion by class II and class III viral proteins. Mol Biol Cell 2010; 21:2001-12. [PMID: 20427575 PMCID: PMC2883944 DOI: 10.1091/mbc.e09-10-0904] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022] Open
Abstract
Fusion of virions pseudotyped with a class II, SFV E1 or VEEV E, or a class III protein, VSV G is promoted by negative potentials and hindered by positive potentials across the target cell. Hemifusion is independent of polarity. Reversion of hemifused membranes into two distinct ones is responsible for voltage-dependence and inhibition of fusion. Voltage was investigated as a factor in the fusion of virions. Virions, pseudotyped with a class II, SFV E1 or VEEV E, or a class III protein, VSV G, were prepared with GFP within the core and a fluorescent lipid. This allowed both hemifusion and fusion to be monitored. Voltage clamping the target cell showed that fusion is promoted by a negative potential and hindered by a positive potential. Hemifusion occurred independent of polarity. Lipid dye movement, in the absence of content mixing, ceased before complete transfer for positive potentials, indicating that reversion of hemifused membranes into two distinct membranes is responsible for voltage dependence and inhibition of fusion. Content mixing quickly followed lipid dye transfer for a negative potential, providing a direct demonstration that hemifusion induced by class II and class III viral proteins is a functional intermediate of fusion. In the hemifused state, virions that fused exhibited slower lipid transfer than did nonfusing virions. All viruses with class II or III fusion proteins may utilize voltage to achieve infection.
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Affiliation(s)
- Ruben M Markosyan
- Department of Molecular Biophysics and Physiology, Rush University Medical Center, Chicago, IL 60612, USA
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15
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Nagai K, Ishida T, Hashimoto T, Harada Y, Ueno S, Ueda Y, Kubo H, Iwao Y. The Sperm-surface glycoprotein, SGP, is necessary for fertilization in the frog, Xenopus laevis. Dev Growth Differ 2009; 51:499-510. [PMID: 19469788 DOI: 10.1111/j.1440-169x.2009.01112.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
To identify a molecule involved in sperm-egg plasma membrane binding at fertilization, a monoclonal antibody against a sperm-surface glycoprotein (SGP) was obtained by immunizing mice with a sperm membrane fraction of the frog, Xenopus laevis, followed by screening of the culture supernatants based on their inhibitory activity against fertilization. The fertilization of both jellied and denuded eggs was effectively inhibited by pretreatment of sperm with intact anti-SGP antibody as well as its Fab fragment, indicating that the antibody recognizes a molecule on the sperm's surface that is necessary for fertilization. On Western blots, the anti-SGP antibody recognized large molecules, with molecular masses of 65-150 kDa and minor smaller molecules with masses of 20-28 kDa in the sperm membrane vesicles. SGP was distributed over nearly the entire surface of the sperm, probably as an integral membrane protein in close association with microfilaments. More membrane vesicles containing SGP bound to the surface were found in the animal hemisphere compared with the vegetal hemisphere in unfertilized eggs, but the vesicle-binding was not observed in fertilized eggs. These results indicate that SGP mediates sperm-egg membrane binding and is responsible for the establishment of fertilization in Xenopus.
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Affiliation(s)
- Keita Nagai
- Laboratory of Molecular Developmental Biology, Graduate School of Medicine, Yamaguchi University, Yamaguchi 753-8512, Japan
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16
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Okamura Y. Biodiversity of voltage sensor domain proteins. Pflugers Arch 2007; 454:361-71. [PMID: 17347852 DOI: 10.1007/s00424-007-0222-6] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2006] [Accepted: 01/26/2007] [Indexed: 10/23/2022]
Abstract
The six-transmembrane type voltage-gated ion channels play an essential role in neuronal excitability, muscle contraction, and secretion. The voltage sensor domain (VSD) is the key element of voltage-gated ion channels for sensing transmembrane potential, and has been studied at the levels of both biophysics and protein structure. Two recently identified proteins containing VSD without a pore domain showed unexpected biological roles: regulation of phosphatase activity and proton permeation. These proteins not only provide novel platforms to understand mechanisms of voltage sensing and ion permeation but also highlight previously unappreciated roles of membrane potential in non-neuronal cells.
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Affiliation(s)
- Yasushi Okamura
- Section of Developmental Neurophysiology, Okazaki Institute for Integrative Bioscience, National Institutes of Natural Sciences, Higashiyama 5-1, Myodaiji-cho, Okazaki, Aichi, 444-8787, Japan.
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17
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Abstract
Fertilization is the union of a single sperm and an egg, an event that results in a diploid embryo. Animals use many mechanisms to achieve this ratio; the most prevalent involves physically blocking the fusion of subsequent sperm. Selective pressures to maintain monospermy have resulted in an elaboration of diverse egg and sperm structures. The processes employed for monospermy are as diverse as the animals that result from this process. Yet, the fundamental molecular requirements for successful monospermic fertilization are similar, implying that animals may have a common ancestral block to polyspermy. Here, we explore this hypothesis, reviewing biochemical, molecular, and genetic discoveries that lend support to a common ancestral mechanism. We also consider the evolution of alternative or radical techniques, including physiological polyspermy, with respect to our ability to describe a parsimonious guide to fertilization.
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Affiliation(s)
- Julian L Wong
- Department of Molecular Biology, Cellular Biology, and Biochemistry, Brown University, Providence, Rhode Island 02912, USA
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18
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Sato KI, Iwasaki T, Hirahara S, Nishihira Y, Fukami Y. Molecular dissection of egg fertilization signaling with the aid of tyrosine kinase-specific inhibitor and activator strategies. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2004; 1697:103-21. [PMID: 15023354 DOI: 10.1016/j.bbapap.2003.11.017] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/01/2003] [Accepted: 11/12/2003] [Indexed: 11/28/2022]
Abstract
Fertilization is triggered by sperm-egg interaction and fusion that initiate a transient rise(s) in the free intracellular calcium ([Ca(2+)](i)) that is responsible for a series of biochemical and cell biological events, so-called "egg activation". Calcium-dependent egg activation leads to the initiation of developmental program that culminates in the birth of individuals. A growing body of knowledge has uncovered the molecular mechanisms underlying sperm-induced transient [Ca(2+)](i) increase(s) to some extent; namely, in most animals so far studied, a second messenger inositol 1,4,5-trisphosphate (IP(3)) seems to play a pivotal role in inducing [Ca(2+)](i) transient(s) at fertilization. However, signaling mechanisms used by sperm to initiate IP(3)-[Ca(2+)](i) transient pathway have not been elucidated. To approach this problem, we have employed African clawed frog, Xenopus laevis, as a model animal and conducted experiments designed specifically to determine the role of the Src family protein-tyrosine kinases (SFKs or Src family PTKs) in the sperm-induced egg activation. This review compiles information about the use of PTK-specific inhibitors and activators for analyzing signal transduction events in egg fertilization. Specifically, we focus on molecular identification of Xenopus Src and the signaling mechanism of the Src-dependent egg activation that has been established recently. We also summarize recent advances in understanding the role of the Src family kinases in egg fertilization of other model organisms, and discuss future directions of the field.
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Affiliation(s)
- Ken-ichi Sato
- Research Center for Environmental Genomics, Kobe University, 1-1 Rokkodai-cho, Nada, Kobe 657-8501, Japan
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19
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Abstract
In marine invertebrates, as in most other organisms, normal development requires that only one sperm nucleus joins with the egg nucleus at fertilization. The principal mechanisms employed are (1) prevention of sperm-egg plasma membrane fusion and (2) modifications of the egg extracellular coat to prevent sperm binding and/or penetration. In a third strategy, fertilization is polyspermic, but only one sperm nucleus fuses with the egg nucleus. Other factors such as gamete density during spawning, chemotaxis, and localized sites for sperm entry may also affect the numbers of sperm reaching the egg.
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Affiliation(s)
- Meredith C Gould
- Instituto de Biología Celular y Molecular, Universidad Autónoma de Baja California, Ensenada 22800, B.C. Mexico.
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20
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Glahn D, Nuccitelli R. Voltage-clamp study of the activation currents and fast block to polyspermy in the egg of Xenopus laevis. Dev Growth Differ 2003; 45:187-97. [PMID: 12752506 DOI: 10.1034/j.1600-0854.2004.00684.x] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Voltage-clamped mature, jelly-intact Xenopus eggs were used to carefully examine the ionic currents crossing the plasma membrane before, during, and after fertilization. The bulk of the fertilization current was transient, of large amplitude, and reversed at the predicted Cl- reversal potential. However, the large amplitude fertilization current was preceded by a small, step-like increase in holding current. This small increase in holding current is referred to in this paper as Ion to acknowledge its qualitative similarity to the Ion current previously described in the sea urchin. It was observed in both fertilized and artificially activated eggs, and was found to be unaffected by 10 mm tetra-ethyl ammonium (TEA), a concentration found to block K+ currents in Rana pipiens. Current-voltage relationships are presented for the large fertilization potential, and show that the fertilization currents have a marked outward rectification and are voltage sensitive. These properties are in contrast to the total lack of rectification and slight voltage sensitivity seen before or after the fertilization currents. The time required for sperm to fertilize the egg was found to be voltage dependent with a relatively more depolarized voltage requiring a longer time for fertilization to occur. The percentage of eggs blocked with varying potential levels was determined and this information was fitted to a modified Boltzmann equation having a midpoint of -9 mV.
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Affiliation(s)
- David Glahn
- Section of Molecular and Cellular Biology, University of California, Davis, CA 95616, USA
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21
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Abstract
A centrally important factor in initiating egg activation at fertilization is a rise in free Ca(2+) in the egg cytosol. In echinoderm, ascidian, and vertebrate eggs, the Ca(2+) rise occurs as a result of inositol trisphosphate-mediated release of Ca(2+) from the endoplasmic reticulum. The release of Ca(2+) at fertilization in echinoderm and ascidian eggs requires SH2 domain-mediated activation of a Src family kinase (SFK) and phospholipase C (PLC)gamma. Though some evidence indicates that a SFK and PLC may also function at fertilization in vertebrate eggs, SH2 domain-mediated activation of PLC gamma appears not to be required. Much work has focused on identifying factors from sperm that initiate egg activation at fertilization, either as a result of sperm-egg contact or sperm-egg fusion. Current evidence from studies of ascidian and mammalian fertilization favors a fusion-mediated mechanism; this is supported by experiments indicating that injection of sperm extracts into eggs causes Ca(2+) release by the same pathway as fertilization.
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Affiliation(s)
- Linda L Runft
- Department of Physiology, University of Connecticut Health Center, Farmington, Connecticut 06030, USA.
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22
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Iwao Y. Mechanisms of Egg Activation and Polyspermy Block in Amphibians and Comparative Aspects with Fertilization in Other Vertebrates. Zoolog Sci 2000. [DOI: 10.2108/zsj.17.699] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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23
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Sato K, Tokmakov AA, Fukami Y. Fertilization signalling and protein-tyrosine kinases. Comp Biochem Physiol B Biochem Mol Biol 2000; 126:129-48. [PMID: 10874161 DOI: 10.1016/s0305-0491(00)00192-9] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Fertilization is initiated by species-specific gamete cell recognition, i.e. sperm-egg interaction, followed by a rapid and sustained activation of multiple cellular and biochemical events, collectively called 'egg activation', which is indispensable for successful formation of zygotic nucleus and later embryogenesis. It is well known that sperm-induced egg activation is mediated by a transient release of calcium ions that originates from the sperm entry point and propagates through the entire egg cytoplasm. It is unclear, however, what kind of upstream events prelude to the calcium transient after sperm-egg interaction. Recently, much attention has been paid to the role of protein-tyrosine phosphorylation in egg activation process by a number of studies on some well-established model organisms. These includes marine invertebrates, frogs, and mammals. In this review, we will summarize the recent findings that begin to uncover a 'missing link' between sperm-egg interaction and egg activation with emphasis on the role of egg protein-tyrosine kinases (PTKs) in Xenopus egg fertilization.
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Affiliation(s)
- K Sato
- Laboratory of Molecular Biology, Biosignal Research Center, Kobe University, Nada, Japan.
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24
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Shilling FM, Magie CR, Nuccitelli R. Voltage-dependent activation of frog eggs by a sperm surface disintegrin peptide. Dev Biol 1998; 202:113-24. [PMID: 9758707 DOI: 10.1006/dbio.1998.8982] [Citation(s) in RCA: 50] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Fertilin, a sperm protein of the metalloprotease/disintegrin/cysteine-rich (MDC) family, plays a critical role in sperm-egg binding in mammals. Peptides corresponding to the disintegrin domain of fertilin and antibodies against fertilin have been shown to inhibit mammalian sperm-egg binding and fusion. A protein from the same family, xMDC16, was recently cloned from frog (Xenopus laevis) testis and was found to be involved in frog sperm-egg binding. Here we report that xMDC16 is localized predominantly on the posterior surface of egg jelly-activated sperm, and peptides from the disintegrin domain of this protein activate eggs when applied near the egg surface. Egg activation was dependent on (1) specific amino acid residues (KTX); (2) the presence of divalent cations, but not external Ca2+ alone; and (3) voltage across the egg plasma membrane. This is the first demonstration of egg activation in vertebrates by the surface application of a peptide derived from a sperm surface protein, supporting a model for egg activation that involves a signal transducing receptor for sperm in the egg's plasma membrane.
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Affiliation(s)
- F M Shilling
- Section of Molecular and Cellular Biology, University of California at Davis, Davis, California, 95616, USA
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25
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Iwao Y, Yasumitsu K, Narihira M, Jiang J, Nagahama Y. Changes in microtubule structures during the first cell cycle of physiologically polyspermic newt eggs. Mol Reprod Dev 1997; 47:210-21. [PMID: 9136124 DOI: 10.1002/(sici)1098-2795(199706)47:2<210::aid-mrd13>3.0.co;2-3] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
The unfertilized egg of the newt, Cynops pyrrhogaster, has a second meiotic spindle at the animal pole and numerous cortical cytasters. After physiologically polyspermic fertilization, all sperm nuclei incorporated into the egg develop sperm asters, and the cortical cytasters change into bundles of cortical microtubules. The size of the sperm asters in the animal hemisphere is approximately 5.6-fold larger than that in the vegetal hemisphere. Only one sperm nucleus moves toward the center of the animal hemisphere to form a zygote nucleus with the egg nucleus. This movement is inhibited by nocodazole, but not by cytochalasin B. The centrosome in the zygote nucleus divides into two parts to form a bipolar spindle for the first cleavage synchronously with the nuclear cycle, but centrosomes of accessory sperm nuclei in the vegetal hemisphere remained to form monopolar interphase asters and subsequently degenerate around the first cleavage stage. The size of sperm asters in monospermically fertilized Xenopus eggs was approximately 37-fold larger than those in Cynops eggs. Since sperm asters that formed in polyspermically fertilized Xenopus eggs exclude each other, the formation of a zygote nucleus is inhibited. Cynops sperm nuclei form larger asters in Xenopus eggs, whereas Xenopus sperm nuclei form smaller asters in Cynops eggs compared with those in homologous eggs. Since there was no significant difference in the concentration of monomeric tubulin between those eggs, the size of sperm asters is probably regulated by a component(s) in egg cytoplasm. Smaller asters in physiologically polyspermic newt eggs might be useful for selecting only one sperm nucleus to move toward the egg nucleus.
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Affiliation(s)
- Y Iwao
- Department of Biological Science, Faculty of Science, Yamaguchi University, Japan
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26
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Iwao Y, Miki A, Kobayashi M, Onitake K. Activation of Xenopus Eggs by an Extract of Cynops Sperm. (fertilization/egg-activation/polyspermy block/sperm protease). Dev Growth Differ 1994. [DOI: 10.1111/j.1440-169x.1994.00469.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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27
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Arts EG, Kuiken J, Jager S, Hoekstra D. Fusion of artificial membranes with mammalian spermatozoa. Specific involvement of the equatorial segment after acrosome reaction. EUROPEAN JOURNAL OF BIOCHEMISTRY 1993; 217:1001-9. [PMID: 8223623 DOI: 10.1111/j.1432-1033.1993.tb18331.x] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
The fusogenic properties of bovine and human spermatozoa membranes were investigated, using phospholipid bilayers (liposomes) as target membranes. Fusion was monitored by following lipid mixing, as revealed by an assay based on resonance-energy transfer. In addition, fusion was visualized by fluorescence microscopy, using fluorescent lipid vesicles. Cryopreserved bovine sperm fused with liposomes before induction of the acrosome reaction, fluorescence being located in essentially all spermatozoa membrane domains. Fresh bovine and human spermatozoa fused with liposomes only after the induction of the acrosome reaction, as triggered by calcium ionophore A23187 or zonae pellucidae (proteins), while the fluorescence distribution was mainly restricted to the equatorial segment (ES). However, with spermatozoa that had undergone a freeze/thawing cycle, domains other than ES also became labeled. Hence, the redistribution of the lipid probes over the entire membrane occurring during lipid mixing with cryopreserved bovine sperm is probably related to membrane perturbations caused by long-term cryopreservation. Fusion with liposomes was governed by spermatozoa factors and required the presence of acidic phospholipids like cardiolipin and phosphatidylserine in the liposomal bilayer. Incorporation of the zwitterionic lipid phosphatidylcholine in the vesicles inhibited the fusion reaction. Fusion was pH dependent. The results indicate that the ES is the primary domain of spermatozoa membranes that harbours the fusogenic capacity of sperm. Liposomes appear a valuable tool in further characterizing the properties of this domain, which has been claimed [Yanagimachi, R. (1988) in The physiology of reproduction (Knobil, E. & Neill, J., eds) pp. 135-185, Raven Press, New York] to represent the putative, initial fusion site for the oocyte.
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Affiliation(s)
- E G Arts
- Department of Obstetrics and Gynaecology, State University of Groningen, The Netherlands
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28
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McCulloh DH, Chambers EL. Fusion of membranes during fertilization. Increases of the sea urchin egg's membrane capacitance and membrane conductance at the site of contact with the sperm. J Gen Physiol 1992; 99:137-75. [PMID: 1613481 PMCID: PMC2216609 DOI: 10.1085/jgp.99.2.137] [Citation(s) in RCA: 80] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
The early events of fertilization that precede and cause activation of an egg have not been fully elucidated. The earliest electrophysiological change in the sea urchin egg is a sperm-evoked increase of the egg's membrane conductance. The resulting depolarization facilitates entry of the fertilizing sperm and precludes the entry of supernumerary sperm. The sequence of the increase in the egg's membrane conductance, gamete membrane fusion, egg activation, and sperm entry, including causal relationships between these events, are not known. This study reports the use of whole egg voltage clamp and loose patch clamp to monitor simultaneously changes of membrane conductance and capacitance at the site of sperm-egg contact. Measurements were made during sperm-egg interactions where sperm entry readily proceeded or was precluded by maintaining the egg's membrane potential either at large, negative values or at positive values. Whenever the sperm evoked an increase of the egg's membrane conductance, that increase initiated abruptly, was localized to the site of sperm attachment, and was accompanied by a simultaneous abrupt increase of the membrane capacitance. This increase of capacitance indicated the establishment of electrical continuity between gametes (possibly fusion of the gametes' plasma membranes). If sperm entry was blocked by large negative membrane potentials, the capacitance cut off rapidly and simultaneously with a decrease of the membrane conductance, indicating that electrical continuity between gametes was disrupted. When sperm entry was precluded by positive membrane potentials, neither conductance nor capacitance increased, indicating that sperm entry was halted before the fusion of membranes. A second, smooth increase of capacitance was associated with the exocytosis of cortical granules near the sperm in eggs that were activated. Electrical continuity between the gametes always preceded activation of the egg, but transient electrical continuity between the gametes alone was not always sufficient to induce activation.
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Affiliation(s)
- D H McCulloh
- Department of Physiology and Biophysics, University of Miami School of Medicine, Florida 33101
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29
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Longo FJ. Gamete interactions and the fate of sperm organelles in fertilized echinoderm eggs. JOURNAL OF ELECTRON MICROSCOPY TECHNIQUE 1991; 17:246-65. [PMID: 2045961 DOI: 10.1002/jemt.1060170303] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Investigations of gamete fusion, sperm entry and the fate of the sperm nucleus, plasma membrane, mitochondrion, and axonemal complex in fertilized echinoderm eggs are reviewed. The timing of gamete fusion with respect to the onset of electrical activity characteristic of the activated egg and the affects of fixation conditions on the stability of fusing membranes are discussed. Observations from investigations using cationized ferritin labeled gametes and immunogold cytochemistry to demonstrate the mixing of sperm plasma membrane components within the egg plasma membrane, in particular along the surface of the fertilization cone, are compared with results from studies in somatic cells. Transformations of the sperm nucleus into a male pronucleus, consisting of sperm nuclear envelope breakdown, chromatin dispersion, and formation of a pronuclear envelope, are correlated with recent biochemical observation of similar processes in other cellular systems. Fates of the sperm mitochondrion and axonemal complex are examined.
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Affiliation(s)
- F J Longo
- Department of Anatomy, University of Iowa, Iowa City 52242
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30
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Abstract
Fertilization potentials in Pelvetia fastigiata, Fucus vesiculosus, and Fucus ceranoides were studied to examine whether eggs of fucoid algae have an electrical block against polyspermy. The resting potential of eggs of all species was about -60 mV, depolarizing, respectively, to -24 +/- 5 mV (SD, n = 9) for 7.5 +/- 2.1 (n = 8) min, -26 +/- 5 (n = 9) mV for 6.4 +/- 2.3 (n = 9) min, and -24 +/- 6 (n = 5) mV for 6.7 +/- 1.9 (n = 4) min. The depolarization was slower, and the fertilization potential was about 10 mV more negative in eggs of both F. vesiculosus and Pelvetia fertilized in 45-mM Na+ ASW; many of these eggs were polyspermic. Steady current was passed through unfertilized eggs of F. vesiculosus prior to insemination to test the potential dependence of fertilization. Eggs (n = 10) bound sperm at all potentials tested (-45 to -23 mV), but fertilization was prevented if eggs were held at potentials more positive than -45 to -37 mV. Eggs underwent a second depolarization if artificially hyperpolarized to potentials more negative than -50 mV immediately after the rise of a normal fertilization potential. Thus, fucoid eggs have an electrical fast block against polyspermy. Only in F. ceranoides does the formation of the cell wall after fertilization appear to be fast enough (i.e., 3-6 min postfertilization versus at 10-15 min in F. vesiculosus and P. fastigiata) to replace the fertilization potential as a polyspermy block. Nonfertilizing fucoid sperm swim away from the egg surface by 1-3 min after rise of the fertilization potential. This suggests that there is another "intermediate block" against polyspermy.
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Affiliation(s)
- S H Brawley
- Department of Biology, Vanderbilt University, Nashville, Tennessee 37235
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Chapter 3 Electrical Characteristics of Oocytes and Eggs. CURRENT TOPICS IN MEMBRANES 1991. [DOI: 10.1016/s0070-2161(08)60801-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register]
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33
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Iwao Y. An electrically mediated block to polyspermy in the primitive urodele Hynobius nebulosus and phylogenetic comparison with other amphibians. Dev Biol 1989; 134:438-45. [PMID: 2744241 DOI: 10.1016/0012-1606(89)90116-4] [Citation(s) in RCA: 28] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
At fertilization, the egg of the primitive urodele, Hynobius nebulosus, produced a fertilization potential which rose from -12 to +47 mV. A similar activation potential was elicited by pricking with a needle, by applying A23187, or by electric shock. The potential change was mediated by an increased permeability to Cl-. Clamping the egg's membrane potential at +40 mV blocked fertilization, while clamping at +20 mV induced polyspermy. These results indicated the occurrence of an electrical polyspermy block, typical of anurans, but atypical of urodeles. Furthermore, Hynobius eggs fertilized by natural mating incorporated only one sperm nucleus, and experimentally polyspermic eggs underwent multipolar division. Accessory sperm did not degenerate in the egg cytoplasm, indicating lack of an intracellular polyspermy block. By comparison, fertilization of Bufo japonicus (anuran) was also voltage dependent, whereas that of Cynops pyrrhogaster (urodele) was voltage independent. Thus polyspermy prevention mechanisms in Hynobius closely resemble those of anuran amphibians and differ from those of higher urodeles.
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Affiliation(s)
- Y Iwao
- Biological Institute, Faculty of Science, Yamaguchi University, Japan
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