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  • 1
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Group
    Nature 432 (2004), S. 48-52 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] What do male alligators in Florida and male industrial workers in California have in common? The answer is that, in the latter part of the twentieth century, both provided landmark case histories showing the severe effects that pesticides can have on fertility. Since then investigations of the ...
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Group
    Nature 415 (2002), S. 963-963 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] The desperate plight of the human spermatozoon is clearly reflected by the poor fecundity of our species. Human spermatozoa stand apart from the gametes of virtually all other mammals in the paucity of their phenotype, the inadequacy of their function, and the sensitivity to fragmentation of their ...
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Group
    Nature 379 (1996), S. 493-495 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] INFERTILITY affects about one in seven couples in the United Kingdom, and in about half of these cases it is defects in the male partner that cause the failure to conceive. Within the past year, however, new assisted-conception techniques mean that immature spermatozoa taken from testes of men with ...
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 0148-7280
    Keywords: epididymal maturation ; capacitation IBMX ; calmidazolium ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Capacitation of hamster caudal spermatozoa at a density of 1 × 106/ml is associated with a progressive rise in cAMP levels that precedes the onset of hyperactivated motility. This increase is not expressed by caput spermatozoa incubated under identical conditions. Both the incidence of hyperactivation and the rise in cAMP levels are severely attenuated in the absence of exogenous calcium. Neither factor is restored to control levels by the addition of the phosphodiesterase inhibitor IBMX, although in the presence of exogenous calcium, this reagent increased cAMP levels, stimulated percentage motility and advanced the appearance of hyperactivation.Treatment of spermatozoa at a density of 1 × 106/ml with the calmodulin antagonist, calmidazolium (CZ), caused severe disruption of sperm motility and abolished hyperactivation, while causing only a slight reduction in cAMP content. Addition of IBMX in the presence of CZ elevated cAMP content to levels higher than normally observed during capacitation but did not restore either coordinated or hyperactivated motility.To determine both the mechanisms responsible for this elevation of cAMP content and the changes that occur during epididymal maturation to facilitate the expression of this increase, the free cytosolic calcium concentration, ATP levels, and intracellular pH of caput and caudal cells were compared. The calcium content of caudal spermatozoa rose significantly at a time when cAMP levels were increasing, while ATP content and intracellular pH fell. However, the inability of caput spermatozoa to express a rise in cAMP content was not due to deficiencies in any of these factors.These results indicate a positive role for the cAMP rise in the expression of hyperactivated motility and that the fundamental control mechanism governing both these events may be the influx of calcium that accompanies capacitation in this species.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Gamete Research 16 (1987), S. 323-341 
    ISSN: 0148-7280
    Keywords: zona pellucida ; deglycosylation ; antisera ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Zonae pellucidae (ZP) were isolated from 1,500 porcine ovaries and heat solubilized to generate approximately 15 mg ZP glycoprotein. Analysis of this material by isoelectric focusing, one-dimensional electrophoresis, and gas chromatography indicated the presence of a major glycoprotein species that exhibited considerable microheterogeneity with respect to its charge (pI 7.5-3.5) and molecular mass (45-85 kDa) and that contained 39.6% carbohydrate, predominantly N-acetylglucosamine.Chemical deglycosylation of porcine ZP using trifluoromethanesulphonic acid (TFMS) resulted in the production of five discrete protein bands on one-dimensional sodium dodecyl sulphate/polyacrylamide gel electrophoresis (SDS/PAGE) with molecular masses of 66, 52, 36, 32, and 16 kDa.Antisera raised in rabbits and marmosets to ZP and/or deglycosylated ZP (DGZP) were used in immunoblotting experiments to demonstrate the retention of immunogenicity by DGZP and the cross-reactivity of the antisera with their heterologous antigen. These studies indicated that antisera that were capable of inhibiting the fertility of primates in vivo and the penetration of the human ZP in vitro reacted preferentially with 3 of the 5 products of deglycosylation, with molecular masses of 66, 52, and 36 kDa. Anti-DGZP antibodies were also shown to interact with intact porcine and human ZP and, with the latter, to block the ability of human spermatozoa to both bind to and penetrate this structure.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 0148-7280
    Keywords: deglycosylated polypeptides ; porcine zonae pellucidae ; mammalian oocyte ; contraceptive potential ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The major deglycosylated polypeptides of the porcine zona pellucida (ZP), with molecular masses of 66, 52, 36, and 32 kDa, were purified to homogenity with one-dimensional sodium dodecyl sulphate/polyacrylamide gel electrophoresis (SDS/PAGE). Immunofluorescence studies demonstrated that antibodies to the DGZP fraction, and the 66- and 32-kDa polypeptides, bound predominantly to the outer ZP; however, only the first two of these antisera formed an immunoprecipitate around the outer human ZP. In immunoblotting experiments using polyclonal antisera raised to these molecules all four polypeptides exhibited cross-reactivity with each other and their parental glycoprotein families (ZP 1-4). In addition, the antisera were tested in an in vitro human gamete bioassay to determine their contraceptive potential; antibodies to the 32-kDa deglycosylated polypeptide inhibited human gamete interaction to the greatest extent, 5.3% (± 1.2%), relative to a control value of 100%.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Gamete Research 15 (1986), S. 57-71 
    ISSN: 0148-7280
    Keywords: Quin-2 ; calcium-45 ; calcium channels ; ionomycin ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Methods for the investigation of cell-associated calcium and intracellular calcium were studied in washed ejaculated human spermatozoa. Experiments using 45Ca2+ indicated that human spermatozoa were permeant to calcium and that a significant proportion of the cellassociated calcium (approximately 50%) was accumulated in the mitochondrion. This necessitated the use of alternative procedures to measure cytoplasmic free calcium. The ability of human spermatozoa to accumulate and de-esterify the intracellular fluorescent calcium indicator Quin-2 was established. Using this technique, the resting level of free intracellular calcium in human spermatozoa was found to be 146.0 ± 19.9 nM, and was significantly elevated upon addition of the divalent cation ionophore ionomycin. In further experiments designed to illustrate the applications of the Quin technique, data was obtained suggesting that the mechanisms controlling intracellular calcium in human spermatozoa are temperature dependent but do not involve voltage-sensitive calcium channels.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Molecular Reproduction and Development 1 (1989), S. 201-207 
    ISSN: 1040-452X
    Keywords: Spermatozoa ; Human ; In situ hybridisation ; Y chromosome ; Sperm selection ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: In situ hybridisation of a Y chromosome-specific DNA probe to preparations of decondensed spermatozoa revealed approximately 46.7% labelled spermatozoa among 3,900 scored. This is not significantly different from the 50% expected if only the Y chromosome-bearing spermatozoa are hybridised. Control hybridisations of Escherichia coli DNA and salmon testis DNA to decondensed sperm produced no significant labelling, whereas more than 99% of the spermatozoa were heavily labelled after hybridisation to total human DNA. These controls indicate that the methodology described in this paper renders the chromatin accessible for hybridisation and that the 50% hybridisation observed with the Y chromosome DNA probe was specific. In situ hybridisation with the Y probe therefore identifies the Y-bearing spermatozoa, and the protocol described should prove useful in evaluating methods of separating Y-bearing and X-bearing spermatozoa.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 151 (1992), S. 466-477 
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: We have shown that human spermatozoa generate and release reactive oxygen species that can be detected by chemiluminescence techniques. Analysis of the cellular mechanisms responsible for this activity suggests that the probe, luminol, undergoes an intracellular dioxygenation reaction mediated by hydrogen peroxide and a sperm peroxidase located within the acrosome. Support for this model included the following observations: (1) the luminol-dependent signal could be suppressed with peroxidase inhibitors, phenylhydrazine and sodium azide; (2) this suppression could be reversed by the addition of an azide-insensitive peroxidase, horse radish peroxidase (HRP); (3) inhibition of intracellular superoxide dismutase (SOD) with potassium cyanide (KCN) suppressed the luminol signal; (4) peroxidase activity could be detected in purified populations of human spermatozoa with 3,3′,5,5′ tetramethylbenzidine (TMB); (5) this peroxidase was active at the pH prevailing within the acrosomal vesicle; and (6) peroxidase activity and luminol-dependent chemiluminescence were minimal in spermatozoa exhibiting a congenital absence of acrosomes. Human spermatozoa could also generate lucigenin-dependent chemiluminescent signals that could neither be suppressed with peroxidase inhibitors nor enhanced by the addition of peroxidase. However, these signals could be enhanced by suppression of intracellular SOD with KCN or inhibited by exogenous SOD, suggesting that lucigenin was responding to superoxide anion released into the extracellular space. The ability of chemiluminescent techniques to detect and discriminate the production of superoxide and hydrogen peroxide by spermatozoa should facilitate the further analysis of reactive oxygen species as mediators of normal and abnormal human sperm function. © 1992 Wiley-Liss, Inc.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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