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Query: UNIPROT:P06889 (Mol)
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The acrosome reaction (AR) was induced in sperm from the brachyuran crustacean Uca tangeri either by mixing male and female gametes in filtered seawater or by treating the spermatozoa with the divalent cation ionophore A23187. This latter method provided a sufficient number of reacted spermatozoa to allow a detailed ultrastructural study of the AR. The process consists of two separate phases: a) initial release of the acrosomal vesicle contents, and b) further elongation of the acrosomal filament, which causes reversal of the rigid capsule limiting the acrosomal vesicle contents. The elongate acrosomal filament consists of an apical perforatorium and a basal columnar structure called here the proximal piece. The former derives from the perforatorium of the uninduced sperm stage with only small ultrastructural changes. The proximal piece forms from myelin-like membrane layers which are initially distributed all around the subacrosomal region and then accumulate in a column at the perforatorial base, thus promoting a sudden forward projection of the perforatorium. The AR in brachyurans is thought to be a passive mechanism that utilizes the negative pressure exerted on the nucleus--caused by emptying of the acrosomal vesicle--for an organized accumulation of membrane-rich material immediately behind the perforatorium, with the final result of the raising of a 3 microns long acrosomal filament.
Mol Reprod Dev 1992 Oct
PMID:Structural changes in sperm from the fiddler crab, Uca tangeri (Crustacea, Brachyura), during the acrosome reaction. 141 89

Fertilization involves adhesive interactions between gametes similar to those mediated by fibronectin (FN) in other cellular systems. Fibronectin has been found on the equatorial segment of ejaculated human serum. As sperm capacity to interact with the oocyte is acquired during epididymal transit, the possible participation of FN in human sperm maturation was studied. The presence of FN in both epididymal sperm and fluid was demonstrated by the detection of a major component of 220 kD in immunoblot studies using anti-FN antisera. The concentration of FN in soluble tissue extracts of epididymis was determined by enzyme-linked immunosorbent assay (ELISA). A gradual increase along the length of the organ, averaging 12-fold from proximal caput to distal corpus, was detected. Immunocytochemistry assays indicated that the number of spermatozoa with immunoreactive FN over the equatorial segment increased from 18% in caput to 64% in distal corpus epididymis. Immunoprecipitation of medium from epididymal explants culture with anti-FN antiserum demonstrated the de novo synthesis of FN in vitro. The greater number of FN-positive sperm coincident with FN accumulation in distal regions of the epididymis supports the role of FN in sperm maturation.
Mol Reprod Dev 1992 Dec
PMID:Characterization of fibronectin as a marker for human epididymal sperm maturation. 147 75

In order to identify human sperm surface proteins involved in the gamete recognition process, mouse monoclonal antibodies were directed against human spermatozoa and screened with live spermatozoa by enzyme-linked immunosorbent assay (ELISA). Immunoperoxidase staining of human testis showed the early presence of four corresponding proteins on germinal cells, while six were detected primarily in testis fluid. The presence of 17 proteins was evidenced in the epididymis. Eight were detected with a decreasing gradient from the beginning to the end of the organ, including vasa efferentia for three of them. The other nine were observed in only one defined segment, usually the caput epididymis, which was found to be the most active region. Comparison of spermatozoa patterns from testis, vasa efferentia, and the three regions of epididymis pointed out a progressive coating. By contrast, three antibodies displayed a migration of spermatozoa surface domains in the course of epididymal transit. Six antibodies were found to inhibit human spermatozoa adherence to zona-free hamster oocytes, while nine promoted it. Molecular weights of antigens corresponding to nine of the antibodies ranged from 11 to 215 kDa. No correlation could be established with previously described human proteins. These observations emphasize the role of epididymis in human sperm maturation.
Mol Reprod Dev 1992 Dec
PMID:Human sperm proteins from testicular and epididymal origin that participate in fertilization: modulation of sperm binding to zona-free hamster oocytes, using monoclonal antibodies. 147 77

The objectives of this study were to compare the fertilization rate of bovine in vitro matured oocytes by in vitro fertilization (IVF) and by microinjection of a single spermatozoon (MI) and to relate these rates with fertility reported for these bulls in artificial breeding. Bull A (Holstein) had a nonreturn rate of 75%. Semen from this bull is routinely used in our standard IVF procedure. Bull B (Ayrshire), used regularly in artificial breeding and related to bull D, had a nonreturn rate of 69.2%. Bull C (Brown Swiss), with a chromosomal translocation and trisomy, achieved a nonreturn rate of 42%. Bull D (Ayrshire) produced nonmotile spermatozoa (SPZ) and had an abnormality described as "tail stump defect." No pregnancies sired by bull D have been reported. Oocytes were either fertilized in vitro by capacitated SPZ or by microinjection of a single immobilized SPZ into the ooplasm. SPZ were treated with 0.1 microM A23187 and used for IVF. For microinjection SPZ were cocultured for 5 h with bovine oviduct epithelial cells (BOEC) and then immobilized by freezing and thawing twice without cryoprotectant. A single batch of killed SPZ (stored at -25 degrees C) was used for all microinjections. All oocytes were cultured in Medium 199 for 22 h at 39 degrees C and subsequently fixed, stained, and examined for evidence of fertilization (i.e., female and male pronucleus formation, SPZ decondensation). Fertilization rates following IVF with semen from bulls A, B, C, and D were 80%, 54%, 1%, and 2%, and following microinjection were 39%, 22%, 21%, and 34%, respectively.
Mol Reprod Dev 1992 Dec
PMID:A comparison between in vitro fertilization and microinjection of immobilized spermatozoa from bulls producing spermatozoa with defects. 147 79

Various morphological aspects of in vivo egg maturation and sperm-egg interaction were investigated in the Australian marsupial Sminthopsis crassicaudata with the transmission and scanning electron microscopes. Cortical granules invariably occurred in primary oocytes, with the number increasing after resumption of the first meiotic division. They generally occurred close to the oolemma, including the region near the oocyte nucleus. After mating, spermatozoa with intact acrosomes, which had a homogeneous electron-dense matrix, were found on the outer zona surface, but loss of acrosomal contents had occurred by the time of zona penetration. Sperm incorporation into the egg took place at the metaphase II stage of meiosis, and, at this time, cortical granules disappeared from the egg cortex. Sperm heads with condensed chromatin in the egg cytoplasm had an electron-dense layer of subacrosomal material over part of the dorsal nuclear surface, but no membranes were present around these incorporated spermatozoa. Sperm chromatin decondensation resulted in an elevation of egg cytoplasm, and the cell membrane over this area lacked microvilli. The pronuclear envelope was not laid down until after chromatin decondensation had occurred. By this time the fertilized egg had reached the uterus, and a smooth, electron-dense, shell membrane had been deposited. These observations, together with our previous findings, indicate that some of the processes of sperm-egg interaction are similar to those in eutherian mammals, whereas others appear highly divergent.
Mol Reprod Dev 1992 Jul
PMID:Marsupial fertilization: some further ultrastructural observations on the dasyurid Sminthopsis crassicaudata. 149 77

In Ciona intestinalis a chymotrypsin-like activity is involved in sperm penetration of the egg vitelline coat. A chymotrypsin-like enzyme has been purified from spermatozoa by a protocol including ion exchange chromatography, gel filtration, and native polyacrylamide gel electrophoresis. The purified enzyme resulted homogeneous when analyzed by SDS-PAGE. The molecular weight of the chymotrypsin-like enzyme was estimated to be 35 kDa by gel filtration and 24 KDa by SDS-PAGE in nonreducing conditions. The pH optimum of the enzyme is 8.4 and its activity is enhanced by Ca2+. It shows the highest activity towards the synthetic substrate Suc-Ala-Ala-Pro-Phe-AMC. Furthermore, by electron microscopy, the purified enzyme affects the structure of egg vitelline coat, and thus it fulfills one of the criteria of a lysin.
Mol Reprod Dev 1992 Aug
PMID:Purification and characterization of a vitelline coat lysin from Ciona intestinalis spermatozoa. 149 86

A group of low Mr (16 kDa-23 kDa) glycoproteins on ejaculated boar spermatozoa have been shown to have high affinity for homologous zona pellucida glycoproteins (ZPGPs). These ZPGP binding proteins are derived from seminal plasma as shown by their absence from epididymal spermatozoa and their presence in seminal plasma as identified by N-terminal amino acid sequence analysis. They bind to ZPGPs by a polysulphate recognition mechanism similar to that found for proacrosin-ZPGP interactions. The haemagglutination activity of boar seminal plasma is also associated with these low Mr glycoproteins. It is suggested that they play a role in regulating the rate of sperm capacitation and survival in the female reproductive tract.
Mol Reprod Dev 1992 Sep
PMID:Characterization of low Mr zona pellucida binding proteins from boar spermatozoa and seminal plasma. 151 Aug 40

Caltrin proteins from seminal vesicle content of the guinea pig bind with great specificity to different regions of the spermatozoa. Indirect immunofluorescence studies with polyclonal antibodies showed that caltrin I binds to the head, on the acrosomal cup, while caltrin II binds on the principal tail and the neck. No fluorescence was detected either in the midpiece or in the post-acrosomal area of the head when sperm were exposed to either of the caltrins. Calcium-induced hyaluronidase release, which occurs during the acrosomal reaction, was dramatically inhibited by caltrin I (approximately 85% inhibition). Caltrin II was less effective in preventing the enzyme release (approximately 50% inhibition). Chemical modification of the structure modified the biological activity of the two caltrins. Reduction and carboxymethylation of the cysteine residues diminished the inhibitory activity on 45Ca2+ uptake and reduced the ability of the proteins to react with their antibodies. Removal of the carbohydrate portion by chemical deglycosylation transformed the inhibitor proteins into enhancers of calcium uptake into the spermatozoa. Caltrin proteins from the guinea pig appear to play the same physiological role as bovine caltrin, regulating specifically calcium transport across the spermatozoal membranes related with the acrosome reaction and hyperactivation process. The dual behavior of caltrins to inhibit or enhance Ca2+ uptake enables them to fulfill this function. Nevertheless, molecular mechanisms different from those described for bovine caltrin seem to be involved in the control of the functional activity of the guinea pig caltrins.
Mol Reprod Dev 1992 Sep
PMID:Functional properties of caltrin proteins from seminal vesicle of the guinea pig. 151 Aug 47

A personal computer-controlled micromanipulation system was developed for automatic injection of spermatozoa into the perivitelline space of mouse ova. A pair of three-dimensional hydraulic micromanipulators driven by pulse motors was used for this automatic system. The pulse signals that regulate the motors are initiated by the computer program, and these signals cause the micromanipulator to move the microtool precisely. The computer program was designed to perform the most effective movements of the sperm injection needle used during manual micromanipulation. Prior to the manipulation, the computer locates the tip of the injection needle and the end of the egg-holding pipette in the microscope field using image processing. The trajectory of the injection needle is determined according to these initial positions. Using this robotic system, subzonal insemination with a single mouse spermatozoon was attempted in a total of 143 ova. The sperm insertion was successfully completed in all cases without damaging any of the ova. Spermatozoa treated with ionophore A23187 and those without the treatment were used. The fertilization rate (68.8%) of the ova inseminated with treated sperm was significantly higher than that (37.5%) obtained with the nontreated sperm (P less than 0.05). These findings suggest the feasibility and potential for further applications of a robotic microinsemination system and, in addition, that a higher fertility rate in the subzonal insemination of mouse ova can be achieved with the ionophore treatment of spermatozoa.
Mol Reprod Dev 1992 Sep
PMID:Subzonal insemination of a single mouse spermatozoon with a personal computer-controlled micromanipulation system. 151 Aug 48

Biochemical and immunoelectron microscopic methods have been used to analyze the distribution of actin in boar spermatozoa and its state of aggregation before and after acrosome reaction. F-actin was detected on sperm head and tail by electron microscopy using an improved phalloidin probe: incubation with a fluorescein-phalloidin complex and an anti-fluorescein antibody, followed by labeling with protein A-gold complex. Gold particles, indicating the presence of F-actin, were localized on the sperm surface of the acrosome-reacted spermatozoa. Specific labeling was localized (1) between the outer acrosomal membrane and the plasma membrane in the equatorial region, (2) between the outer surface of the fibrous sheath and the plasma membrane in the postacrosomal region, (3) around the connecting piece and the neck region, and (4) on the external surface of the fibrous sheath in the principal piece of the tail. Furthermore, after NP-40 extraction, the SDS-PAGE revealed a difference in solubility between reacted and unreacted boar spermatozoa, reflecting actin polymerization. We conclude that most actin in the acrosome reacted boar spermatozoa is polymeric.
Mol Reprod Dev 1992 Sep
PMID:F-actin in acrosome-reacted boar spermatozoa. 151 Aug 50


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