Abstract

Sperm structure has evolved to be very compact and compartmentalized to enable the motor (the flagellum) to transport the nuclear cargo (the head) to the egg. Furthermore, sperm do not exhibit progressive motility and are not capable of undergoing acrosomal exocytosis immediately following their release into the lumen of the seminiferous tubules, the site of spermatogenesis in the testis. These cells require maturation in the epididymis and female reproductive tract before they become competent for fertilization. Here we review aspects of ...

Abstract

Sperm undergo extreme variations in temperature and osmolality during cryopreservation, resulting in cell damage that includes plasma membrane defects, changes in cell volume, decreased motility, and flagellar defects. However, the fundamental biologic mechanisms underlying these events are poorly understood. We investigated the effects of osmotic stress and cytochalasins b (CB) and d (CD), naturally occurring toxins that disrupt actin organization, on the actin cytoskeleton and motility of Rhesus macaque sperm (Macaca mulatta). Sperm were diluted in media of low, medium, or ...

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ISI Document Delivery No.: 235ET Times Cited: 5 Cited Reference Count: 68 Cited References: AGCA Y, 2005, CRYOBIOLOGY, V51, P1, DOI 10.1016/j.cryobiol.2005.04.004 AIZAWA H, 1999, GENES CELLS, V4, P311 AKTORIES K, 2004, REV PHYSL BIOCH PHAR, V152, P1 AMANN RP, 1993, J ANDROL, V14, P397 AZAMAR Y, 2007, MOL REPROD DEV, V74, P312, DOI 10.1002/mrd.20578 BREITBART H, 2005, REPRODUCTION, V129, P263, DOI 10.1530/rep.1.00269 BRENER E, 2003, BIOL REPROD, V68, P837, DOI 10.1095/biolreprod.102.009233 CAMITINI M, 1992, MICROSC RES TECHNIQ, V20, P232 CANTIELLO HF, 1997, J EXP ZOOL, V279, P425 CARR DW, 2001, J BIOL CHEM, V276,

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DA - 19950216 IS - 0303-4569 (Print) IS - 0303-4569 (Linking) LA - eng PT - In Vitro PT - Journal Article RN - 0 (Chorionic Gonadotropin) RN - 33515-09-2 (Gonadotropin-Releasing Hormone) RN - 61489-71-2 (Menotropins) RN - 911-45-5 (Clomiphene) SB - IM

Abstract

Not all biological movements are caused by molecular motors sliding along filaments or tubules. Just as springs and ratchets can store or release energy and rectify motion in physical systems, their analogs can perform similar functions in biological systems. The energy of biological springs is derived from hydrolysis of a nucleotide or the binding of a ligand, whereas biological ratchets are powered by Brownian movements of polymerizing filaments. However, the viscous and fluctuating cellular environment and the mechanochemistry of soft biological ...

Abstract

Spermatogenesis is the process by which spermatogonial stem cells divide and differentiate to produce sperm. In vitro sperm production has been difficult to achieve because of the lack of a culture system to maintain viable spermatogonia for long periods of time. Here we report the in vitro generation of spermatocytes and spermatids from telomerase-immortalized mouse type A spermatogonial cells in the presence of stem cell factor. This differentiation can occur in the absence of supportive cells. The immortalized spermatogonial cell line ...

Abstract

We report that full-length and truncated transcripts of Fyn tyrosine protein kinase are expressed during testicular development. Truncated Fyn (tr-Fyn) transcripts encode a 24 kDa protein with a N-terminal (NT) domain, a complete Src homology (SH) 3 domain and an incomplete SH2 domain. The kinase domain is missing in tr-Fyn. In contrast, full-length Fyn transcripts encode a 59-55 kDa protein. Fractionated spermatids by centrifugal elutriation express tr-Fyn transcripts and protein, but not full-length Fyn transcripts and protein. Neither full-length Fyn nor tr-Fyn transcripts ...

Abstract

Mammalian sperm must have properly formed acrosomes to be fully functional in the process of binding and penetrating the zona pellucida (ZP), the extracellular matrix surrounding the egg. There is much evidence to raise doubts about the old "bag of enzymes" paradigm of acrosomal function, although this is the model that seems to prevail. We concur with other scientists that acrosomal exocytosis is not an all or none event where the acrosome is either "intact" or "reacted". As determined by transmission ...

Abstract

BACKGROUND: Cryopreservation/thawing of bovine spermatozoa induces a reduction in cell viability and is possibly associated with a form of programmed cell death that we previously named 'apoptosis-like phenomenon'. METHODS: In this study, we specified, by flow cytometry, the moment of appearance of some characteristics of apoptosis during the cryopreservation process. We also studied the presence and/or activation in bovine sperm cells of specific proteins involved in somatic cell apoptosis by western blot and fluorimetry. RESULTS: A decrease of the mitochondrial membrane ...

Abstract

Certain features of capacitated or frozen-thawed spermatozoa have been considered to be an apoptosis-like phenomenon, and, it has been suggested that the presence of apoptotic sperm in seminal doses could be one of the reasons for poor fertility. The objective of this study was to determine whether phosphatidylserine (PS) translocation, caspase activity and DNA fragmentation, which are considered to be apoptotic markers in somatic cells, occur in ram sperm. Fresh ejaculates and sperm samples in different physiological state (cold-shocked, in vitro ...

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LR: 20081121; JID: 7807205; 0 (Amino Acid Chloromethyl Ketones); 0 (Biological Markers); 0 (Enzyme Inhibitors); 0 (Phosphatidylserines); 0 (benzyloxycarbonylvalyl-alanyl-aspartyl fluoromethyl ketone); EC 3.4.22.- (Caspases); 2007/01/15 [received]; 2007/04/03 [revised]; 2007/04/10 [accepted]; 2007/04/20 [aheadofprint]; ppublish

Abstract

Sexual reproduction requires the fusion of sperm cell and oocyte during fertilization to produce the diploid zygote. In mammals complex changes in the plasma membrane of the sperm cell are involved in this process. Sperm cells have unusual membranes compared to those of somatic cells. After leaving the testes, sperm cells cease plasma membrane lipid and protein synthesis, and vesicle mediated transport. Biophysical studies reveal that lipids and proteins are organized into lateral regions of the sperm head surface. A delicate ...

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LR: 20061115; PUBM: Print; JID: 0217513; 0 (Membrane Lipids); 0 (Membrane Proteins); RF: 395; ppublish

Abstract

Ejaculated mammalian sperm must undergo a final maturation (capacitation) before they can acrosome-react and fertilize eggs. Loss of the sperm sterols, cholesterol and desmosterol, is an obligatory step in the capacitation of human sperm. Because sterols can increase the order of membrane phospholipids, it has been suggested that the importance of sterol loss is that it decreases membrane lipid order. The present study tested the hypotheses that sterol loss decreases sperm membrane lipid order during capacitation and that lipid disorder is ...

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LR: 20071114; PUBM: Print-Electronic; GR: HD30763/HD/United States NICHD; DEP: 20030416; JID: 0207224; 0 (Fluorescent Dyes); 0 (Lipids); 0 (Sterols); 100-51-6 (Benzyl Alcohol); 57-88-5 (Cholesterol); 2003/04/16 [aheadofprint]; ppublish

Abstract

Glycosaminoglycans (GAGs) are present in the oviduct in which the major part of sperm capacitation occurs. In this study we have tested how capacitation of frozen-thawed bull spermatozoa is effected by exposure to different GAGs detectable or possibly present in oviductal fluid; i.e. heparin, hyaluronan, heparan sulphate, dermatan sulphate and chondroitin sulphate. Following exposure of different duration, the spermatozoa were stained with either Chlortetracycline (CTC) or merocyanine-540 and evaluated with epifluorescent light microscopy or flow cytometry, respectively. Heparin elicited a significant ...

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JID: 9309124; 0 (Egg Proteins); 0 (Fluorescent Dyes); 0 (Membrane Glycoproteins); 0 (Pyrimidinones); 0 (Receptors, Cell Surface); 0 (zona pellucida glycoproteins); 24967-94-0 (Dermatan Sulfate); 57-62-5 (Chlortetracycline); 58823-12-4 (merocyanine dye); 9005-49-6 (Heparin); ppublish

Abstract

Fertilization typically involves membrane fusion between sperm and eggs. In Drosophila, however, sperm enter eggs with membranes intact. Consequently, sperm plasma membrane breakdown (PMBD) and subsequent events of sperm activation occur in the egg cytoplasm. We previously proposed that mutations in the sneaky (snky) gene result in male sterility due to failure in PMBD. Here we support this proposal by demonstrating persistence of a plasma membrane protein around the head of snky sperm after entry into the egg. We further show ...

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Times Cited: 0 Cited Reference Count: 49 Cited References: ALTSCHUL SF, 1997, NUCLEIC ACIDS RES, V25, P3402 ARAI M, 2004, NUCLEIC ACIDS RES S2, V32, W390 ARIOLI T, 1998, SCIENCE, V279, P717 BACCETTI B, 1972, ADV INSECT PHYSIOL, V9, P315 BACCETTI B, 1979, SPERMATOZOON, P305 BORDEN KLB, 2000, J MOL BIOL, V295, P1103 COLWIN LH, 1967, FERTILIZATION, P295 COWARD K, 1996, REV FISH BIOL FISHER, V12, P33 DALLAI R, 2003, TISSUE CELL, V35, P19 DEGRUGILLIER ME, 1976, J ULTRASTRUCT RES, V56, P312 DUNINBORKOWSKI OM, 1995, DEV BIOL, V168, P689 EVANS JP, 2002, HUM REPROD UPDATE,

Abstract

Sp17 was initially thought to be a sperm specific protein involved in the interaction of the spermatozoon with the oocyte's surrounding extracellular glycoprotein matrix. Recent reports, however, indicate that Sp17 expression is neither testis-specific nor is it exclusively used for binding to the zona pellucida of the oocyte. In this study, we provide comprehensive characterization of the genomic structure of Sp17. We identified an intron-containing gene (Sp17-1) containing five exonic and four intronic sequences. Analysis of Sp17 transcripts using rapid amplification ...

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Times Cited: 4 Cited Reference Count: 60 Cited References: ADOYO PA, 1997, MOL REPROD DEV, V47, P66 ALBERTA JA, 1994, J BIOL CHEM, V269, P4532 ALTSCHUL SF, 1990, J MOL BIOL, V215, P403 AYOUBI TAY, 1996, FASEB J, V10, P453 AZIZKHAN JC, 1993, CRIT REV EUKAR GENE, V3, P229 BARD JA, 1995, GENE, V153, P295 BARSKI OA, 1999, GENOMICS, V60, P188 BOGUSKI MS, 1993, NAT GENET, V4, P332 BUCHLI R, 1999, J CELL BIOCHEM, V74, P264 CAPUT D, 1986, P NATL ACAD SCI USA, V83, P1670 CHEN HM, 1999, HUM GENET, V105, P399 CHIRIVAINTERNATI M,

Abstract

Spermatid differentiation markers such as the acrosomal protein SP-10 display remarkable testis- and germ cell-restricted gene expression. However, little is known about the mechanisms that prevent their expression in somatic tissues. We have previously noted that the -408/+28 or the -266/+28 promoter of SP-10 directed strictly spermatid-specific transcription in transgenic mice, Biol. Reprod. 61, 1256-1266). Lack of ectopic expression in these mouse lines implied that the SP-10 promoter might have protected the transgene from the influence of neighboring enhancers. The present ...

Abstract

The acrosomal process of the sperm of the horseshoe crab (Limulus polyphemus) is a unique crystalline actin bundle, consisting of multiple actin filaments cross-linked by the actin-bundling protein, scruin. For successful fertilization, the acrosomal bundle must penetrate through a 30 microm thick jelly coat surrounding the egg and thus it must be sufficiently stiff. Here, we present two measurements of the bending stiffness of a single crystalline bundle of actin. Results from these measurements indicate that the actin:scruin composite bundle has ...

Abstract

During the 5 s of the acrosome reaction of Limulus polyphemus sperm, a 60-microm-long bundle of scruin-decorated actin filaments straightens from a coiled conformation and extends from the cell. To identify the motive force for this movement, we examined the possible sources of chemical and mechanical energy and show that the coil releases approximately 10-13 J of stored mechanical strain energy, whereas chemical energy derived from calcium binding is approximately 10-15 J. These measurements indicate that the coiled actin bundle extends ...

Abstract

Frozen, hydrated acrosomal bundles from Limulus sperm were imaged with a 400 kV electron cryomicroscope. Segments of this long bundle can be studied as a P1 crystal with a unit cell containing an acrosomal filament with 28 actin and 28 scruin molecules in 13 helical turns. A novel computational procedure was developed to extract single columns of superimposed acrosomal filaments from the distinctive crystallographic view. Helical reconstruction was used to generate a three-dimensional structure of this computationally isolated acrosomal filament. The ...

Abstract

The acrosomal process of the sperm of the horseshoe crab (Limulus polyphemus) is a unique crystalline actin bundle, consisting of multiple actin filaments cross-linked by the actin-bundling protein, scruin. For successful fertilization, the acrosomal bundle must penetrate through a 30 microm thick jelly coat surrounding the egg and thus it must be sufficiently stiff. Here, we present two measurements of the bending stiffness of a single crystalline bundle of actin. Results from these measurements indicate that the actin:scruin composite bundle has ...

Abstract

During the 5 s of the acrosome reaction of Limulus polyphemus sperm, a 60-microm-long bundle of scruin-decorated actin filaments straightens from a coiled conformation and extends from the cell. To identify the motive force for this movement, we examined the possible sources of chemical and mechanical energy and show that the coil releases approximately 10-13 J of stored mechanical strain energy, whereas chemical energy derived from calcium binding is approximately 10-15 J. These measurements indicate that the coiled actin bundle extends ...

Abstract

Regulated exocytosis in many cells is controlled by the SNARE complex, whose core includes three proteins that promote membrane fusion. Complexins I and II are highly related cytosolic proteins that bind tightly to the assembled SNARE complex and regulate neuronal exocytosis. Like somatic cells, sperm undergo regulated exocytosis; however, sperm release a single large vesicle, the acrosome, whose release has different characteristics than neuronal exocytosis. Acrosomal release is triggered upon sperm adhesion to the mammalian egg extracellular matrix (zona pellucida) to ...

Abstract

Specific binding of spermatozoa to the zona pellucida that surrounds mammalian eggs is a key step in the fertilization process. However, the sperm proteins that recognise zona pellucida receptors remain contentious despite longstanding research efforts to identify them. Here we present evidence that proacrosin, a tissue-specific protein found within the acrosomal vesicle of all mammalian spermatozoa, is a multifunctional protein that mediates binding of acrosome-reacted spermatozoa to zona glycoproteins via a stereospecific polysulfate recognition mechanism. Using sulfated versus non-sulfated forms of ...

Abstract

The extracellular matrix surrounding avian oocytes, called the perivitelline membrane (PL), consists of at least two major glycoproteins, ZP3 and ZP1. Our previous study using Japanese quail had demonstrated that the PL obtained from the preovulatory follicles was incubated in vitro with spermatozoa, and perforations were observed. This result indicated that the PL might contain a constituent that possesses activity to initiate the acrosome reaction (AR) in quail. In order to elaborate upon our previous findings, we evaluated the effects of ...

Abstract

The sperm acrosome reaction takes place in response to progesterone and zona pellucida. Progesterone may act on more than one type of surface receptor, of which one is a gamma-aminobutyric acid (GABA) type A-like receptor. Although there is direct evidence of GABA initiation of mouse sperm acrosome reaction, there are conflicting results regarding GABA-induced exocytosis in human spermatozoa. We have examined whether GABA would initiate exocytosis in human spermatozoa using the chlortetracycline assay and a zona-free hamster oocyte test. Human spermatozoa ...

Abstract

Atce1 belongs to the CREB3/LZIP subtype of the ATF/CREB transcription factor gene family. Its transcription has previously been shown to be testis-specific and within the testis to be restricted to haploid spermatids. In this study, we characterized the protein's distribution in the testis and found that it accumulates in late round and in elongating spermatids, corresponding to developmental stages considered transcriptionally silent. ATCE1 accumulation is acrosome-specific and persists up to mature epididymal cells, at which stage the protein remained associated with ...

Abstract

To explore the biological characteristics of the recombinant zona pellucida 3 (ZP3) peptides of rhuZP3a(22~176) and rhuZP3b(177~348), we examined whether rhuZP3a(22~176) or rhuZP3b(177~348) may trigger acrosome reaction of human spermatozoa and the possible mechanism. The assessment of acrosome reaction was performed using chlortetracycline staining. Intracellular free calcium concentration ([Ca(2+)]i) in Fura-2/AM-loaded human sperm was monitored with spectrofluorophotometer. We found that the peptides rhuZP3a(22~176) and rhuZP3b(177~348) were significantly capable of eliciting acrosome reaction at different concentrations, respectively. With an addition of either ...

Abstract

Sperm of many animals must complete an exocytotic event, the acrosome reaction, in order to fuse with eggs. In mammals, acrosome reactions are triggered during sperm contact with the egg extracellular matrix, or zona pellucida, by the matrix glycoprotein ZP3. Here, we show that ZP3 stimulates production of phosphatidylinositol-(3,4,5)-triphosphate in sperm membranes. Phosphatidylinositol-3-kinase antagonists that prevent acrosome reactions and fertilization in vitro, while generation of this phosphoinositide in the absence of ZP3 triggered acrosome reactions. Downstream effectors of phosphatidylinositol-(3,4,5)-triphosphate in sperm ...

Abstract

The transformation of the nucleus, acrosomic system, and peri-nuclear theca (perforatorium and post-acrosomal dense lamina) was analyzed during the maturation phase, i.e., steps 14 to 19 of spermiogenesis. Following partial condensation of chromatin from steps 11-14, the nucleus continues to condense during the following steps until the end of spermiogenesis. The redundant nuclear envelope which forms along the apical and ventral aspects of the nucleus and around the implantation fossa regresses during steps 17-19. The acrosomic system splits into two portions ...

Abstract

At fertilization, spermatozoa bind to the zona pellucida (ZP1, ZP2, ZP3) surrounding ovulated mouse eggs, undergo acrosome exocytosis and penetrate the zona matrix before gamete fusion. Following fertilization, ZP2 is proteolytically cleaved and sperm no longer bind to embryos. We assessed Acr3-EGFP sperm binding to wild-type and huZP2 rescue eggs in which human ZP2 replaces mouse ZP2 but remains uncleaved after fertilization. The observed de novo binding of Acr3-EGFP sperm to embryos derived from huZP2 rescue mice supports a `zona scaffold' ...

Abstract

To improve assessment of the acrosome reaction of mouse epididymal sperm, we employed anti-Izumo1 antibody instead of antibodies against acrosomal proteins. The acrosomal states among acrosome-intact, spontaneously acrosome-reacted, truly acrosome-reacted, and probably dead and/or membrane-damaged sperm were clearly distinguished by combined application of anti-Izumo1 antibody, DNA dye Hoechst 33342, and monoclonal antibody MN7 to paraformaldehyde-fixed sperm. When the acrosome reaction of capacitated epididymal sperm on the oocyte zona pellucida was examined using anti-Izumo1 antibody, approximately 20% of sperm bound onto the ...

Abstract

In the fertilization process of sea stars, sperm is activated to go through the acrosome reaction before cell fusion. We focused on induction of the acrosome reaction as a key process in fertilization. Six species of sea stars were used in this study: Asterias amurensis, Asterias rubens, Asterias forbesi, Aphelasterias japonica, Distolasterias nipon, and Asterina pectinifera. Acrosome reaction assays indicate that the acrosome reaction can be induced across species within Asteriinae subfamily. However, cross-fertilization assays indicate that sea stars have species ...

Abstract

The morphological and biochemical characteristics of the acrosome depart well from any other vesicles in somatic cells, making it one of a kind amongst secretory vesicles. The components of the acrosome include a mixture of unique enzymes like acrosin and other enzymes that when present in somatic cells are commonly found in lysosomes, peroxisomes, and even in the cytoplasm. Several observations have pointed out that acrosomal biogenesis has unique features not previously described in secretory vesicle biogenesis of somatic cells. In ...

Abstract

As a cell-specific organelle, acrosome (Acr) and its formation are an important event for spermiogenesis. However, the Acr formation is far more complicated than has been proposed. In this study, we have cloned a novel membrane protein Afaf (Acr formation associated factor) that was expressed abundantly in the round spermatids, localized in the inner and outer membrane of forming Acrs, and declined in the maturing Acrs. In the transfected Hela cells, Afaf protein was localized in the plasma membrane, EEA1-positive early ...

Abstract

During fertilization in marine invertebrates, fusion between sperm and egg cell membranes occurs at the tip of the sperm acrosomal process. In abalone sperm the acrosomal process is coated with an 18-kDa protein. In situ, this protein has no effect on the egg vitelline envelope, but in vitro it is a potent fusagen of liposomes. Thus, the 18-kDa protein may mediate membrane fusion between the gametes, a step in gamete recognition known to restrict heterospecific fertilization in other species. The cDNA ...

Abstract

The acrosome is a secretory vesicle attached to the nucleus of the sperm. Our hypothesis is that microtubules participate in the membrane traffic between the Golgi apparatus and acrosome during the first steps of spermatid differentiation. In this work, we show that nocodazole-induced microtubule depolarization triggers the formation of vesicles of the acrosomal membrane, without detaching the acrosome from the nuclear envelope. Nocodazole also induced fragmentation of the Golgi apparatus as determined by antibodies against giantin, golgin-97 and GM130, and electron ...

Abstract

In the mouse, considerable evidence indicates that initial sperm binding to the zona pellucida (ZP) is mediated by ZP3. In addition, this same glycoprotein is also responsible for inducing the acrosome reaction (AR). Whereas the O-linked oligosaccharides of ZP3 appear to mediate sperm-ZP binding, the portion of ZP3 bearing AR activity has not been defined. To try to understand the bifunctional role of ZP3 (binding and AR inducing activities), we have examined the hypothesis that ZP3 aggregates sperm receptor molecules. By ...

Abstract

BACKGROUND: Protein tyrosine phosphorylation (TP) of human sperm is related to sperm capacitation and zona pellucida (ZP) binding. The aim of this study was to determine whether the TP of capacitated sperm is a useful marker for the ability of sperm to bind to the ZP and undergo the ZP-induced acrosome reaction (AR). METHODS: Semen samples were obtained from 115 subfertile men with sperm count >/=20 x 10(6)/ml, motility >/=25% and variable morphology. Motile sperm (2 x 10(6)/ml) selected by swim-up ...

Abstract

Sexual reproduction requires the fusion of sperm cell and oocyte during fertilization to produce the diploid zygote. In mammals complex changes in the plasma membrane of the sperm cell are involved in this process. Sperm cells have unusual membranes compared to those of somatic cells. After leaving the testes, sperm cells cease plasma membrane lipid and protein synthesis, and vesicle mediated transport. Biophysical studies reveal that lipids and proteins are organized into lateral regions of the sperm head surface. A delicate ...

Abstract

Following ejaculation, sperm functions are regulated by interactions with the environment found in the female genital tract. Here spermatozoa become ‘capacitated’ (i.e. they acquire the capability of completing the acrosome reaction and successfully fertilizing the egg), through a series of surface and intracellular transformations occurring during a process known as capacitation. The limited number of spermatozoa that eventually reach the oocyte must then cross the surrounding cumulus cells before contacting the zona pellucida, undergoing the acrosome reaction and finally fertilizing the ...

Abstract

Two processes, namely capacitation and acrosome reaction, are of fundamental importance in the fertilization of oocyte by spermatozoon. Physiologically occurring in the female genital tract, capacitation is a complex process, which renders the sperm cell capable for specific interaction with the oocyte. During capacitation, modification of membrane characteristics, enzyme activity and motility properties of spermatozoa render these cells able to penetrate oocyte investments and responsive to stimuli that induce acrosome reaction prior to fertilization. Physiological acrosome reaction occurs upon interaction of ...

Abstract

In order to fertilize, the mammalian spermatozoa should reside in the female reproductive tract for several hours, during which they undergo a series of biochemical modifications collectively called capacitation. Only capacitated sperm can undergo the acrosome reaction after binding to the egg zona pellucida, a process which enables sperm to penetrate into the egg and fertilize it. Polymerization of globular (G)-actin to filamentous (F)-actin occurs during capacitation, depending on protein kinase A activation, protein tyrosine phosphorylation, and phospholipase D activation. F-actin ...

Abstract

A new electron cryomicroscopic reconstruction of an actin-scruin bundle from Limulus sperm reveals details about the enormous structural plasticity within F-actin. The twist and tilt of the actin subunits show very large deviations from ideal F-actin, providing clues about actin dynamics. ...

Abstract

When Mytilus edulis spermatozoa are exposed to Mytilus egg-water, low temperature or an excess of Ca++, their acrosomes break down and a slender filament is extruded. In order to determine whether this reaction releases an egg-membrane lysin, dense sperm suspensions were stimulated by excess Ca++, and the reacted spermatozoa were centrifuged out of suspension and extracted with sea water after being frozen and ground in a mortar. Tests of this extract and of the supernatant containing the acrosome material, for their ...

Abstract

Suppression of the acrosome reaction of sperm on fertilized oocytes inhibits sperm-oocyte binding and is considered one of the three mechanisms responsible for polyspermy block in oocytes of the mussel Mytilus edulis (Togo et al., 1995). When unfertilized oocytes were inseminated in the presence of aminopeptidase inhibitors and the fertilized oocytes were inseminated again, neither the acrosome reaction nor sperm binding to fertilized oocytes were suppressed, suggesting that aminopeptidase-like protease participates in suppression of the acrosome reaction. The supernatant solution obtained ...

Abstract

The sperm of the mussel Mytilus had hydrolytic activities against substrates for aminopeptidase. Acrosome reaction (AR) was suppressed in the presence of aminopeptidase substrate, Phe-4-methylcoumaryl-7-amide (MCA), and an aminopeptidase inhibitor, bestatin. Treatment of sperm with phosphatidylinositol-specific phospholipase C (PI-PLC) released aminopeptidase activity from sperm and suppressed AR. These results suggest that the enzyme is located on the sperm surface via glycosylphosphatidylinositol (GPI)-anchor and is involved in the AR. Immunoblot analysis showed that tyrosine residues of 40, 59, 68, and 72 kDa ...

Abstract

Acrosomal proteins from Mytilus edulis sperms were separated into 11 fractions by reverse phase HPLC. The three major proteins, named M3, M6, and M7, showed strong egg vitelline coat lysin and first polar body releasing activities. The amino acid sequences of these proteins were determined. M6 and M7 were composed of 180 amino acid residues and showed high sequence homology (76%), while M3 was composed of 149 residues and showed 26% homology with M6 and M7. The disulfide linkage motif of ...