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Human Sperm (human + sperm)
Terms modified by Human Sperm Selected AbstractsEffect of pH on the development of acrosomal responsiveness of human spermANDROLOGIA, Issue 2 2007N. L. Cross Summary Human sperm incubated in vitro gradually become responsive to inducers of the acrosome reaction. The roles of constituents of the incubation medium are not well understood. These experiments tested the effect of the extracellular pH on sperm acrosomal responsiveness. Sperm were incubated 24 h in media with pH varying between 6.7 and 7.6 and then exposed to progesterone to determine the number of sperm that had become acrosomally responsive. The number of responsive sperm was very low following incubation at pH 6.7,7.0, and increased with the pH over the range 7.0,7.6. Sperm incubated at low pH were not damaged as assessed by motility or viability, and if they were transferred to medium of high pH for 8 h, the inhibition of acrosomal responsiveness was reversed. Inhibition of acrosomal responsiveness at low pH was not due to impaired loss of sperm cholesterol, but was correlated with a reduced intracellular pH. The inhibition of acrosomal responsiveness by media of low pH may result from preventing the normal capacitation-related rise in intracellular pH. [source] Role of the Na+/Ca2+ exchanger in calcium homeostasis and human sperm motility regulationCYTOSKELETON, Issue 2 2006Zoltán Krasznai Abstract A number of cell functions, such as flagellar beating, swimming velocity, acrosome reaction, etc., are triggered by a Ca2+ influx across the cell membrane. For appropriate physiological functions, the motile human sperm maintains the intracellular free calcium concentration ([Ca2+]i) at a submicromolar level. The objective of this study was to determine the role of the Na+/Ca2+ exchanger (NCX) in the maintenance of [Ca2+]i in human spermatozoa. Spermatozoa maintained in extracellular medium containing ,1 ,M Ca2+ exhibited motility similar to that of the control. In addition to several calcium transport mechanisms described earlier, we provide evidence that the NCX plays a crucial role in the maintenance of [Ca2+]i. Three chemically unrelated inhibitors of the NCX (bepridil, DCB (3,,4, -dichlorobenzamil hydrochloride), and KB-R7943) all blocked human sperm motility in a dose and incubation time dependent manner. The IC50 values for bepridil, DCB, and KB-R7943 were 16.2, 9.8, and 5.3 ,M, respectively. The treatment with the above-mentioned blockers resulted in an elevated [Ca2+]i and a decreased [Na+]i. The store-operated calcium channel (SOCC) inhibitor SKF 96365 also blocked the sperm motility (IC50 = 2.44 ,M). The presence of the NCX antigen in the human spermatozoa was proven by flow cytometry, confocal laser scanning microscopy, and immunoblotting techniques. Calcium homeostasis of human spermatozoa is maintained by several transport proteins among which the SOCC and the NCX may play a major role. Cell Motil. Cytoskeleton 2006. © 2005 Wiley-Liss, Inc. [source] Gadolinium, a mechano-sensitive channel blocker, inhibits osmosis-initiated motility of sea- and freshwater fish sperm, but does not affect human or ascidian sperm motilityCYTOSKELETON, Issue 4 2003Zoltán Krasznai Abstract Exposure to hypo-osmotic or hyperosmotic environment triggers the initiation of fish sperm motility. In this article, we report that calcium and potassium channel blockers do not influence motility of puffer fish sperm but calmodulin antagonists reversibly decrease it, suggesting that calmodulin,Ca2+ interactions are prerequisite for the initiation of sperm motility in this species. Gadolinium (a stretch activated ion channel blocker) decreased the motility of puffer fish sperm from 92 ± 3% to 6 ± 3% and that of carp sperm from 91 ± 7% to 3.5 ± 4.3% in a dose-dependent manner (10,40 ,M). The effect of gadolinium was reversible, suggesting that stretch activated ion channels participate in the initiation of sperm motility of the two species. Gadolinium inhibits changes in the isoelectric point of certain proteins of puffer fish sperm, which occur when sperm motility is initiated in a hypertonic solution. Anisotropy measurements showed that hypo-osmotic treatment, which initiates carp sperm motility, increased membrane fluidity. When hypo-osmotic treatment was given in the presence of gadolinium, the sperm membrane remained as rigid as in quiescent cells, while motility was blocked. By contrast, gadolinium did not influence the motility parameters of Ciona or human sperm. Based on these lines of evidence, we suggest that conformational changes of mechanosensitive membrane proteins are involved in osmolality-dependent but not osmolality-independent sperm. Cell Motil. Cytoskeleton 55:232,243, 2003. © 2003 Wiley-Liss, Inc. [source] The aetiology of sperm protamine abnormalities and their potential impact on the sperm epigenomeINTERNATIONAL JOURNAL OF ANDROLOGY, Issue 6 2008Douglas T. Carrell Summary During the elongating spermatid stage of spermatogenesis, there is a step-wise replacement of nuclear histones with protamines 1 and 2. In fertile men, the ratio of protamine 1/protamine 2 (P1/P2) is within the narrow range of 0.8,1.2. Ratios above or below that range are associated with infertility, exhibiting a wide range of defects including decreased sperm counts, morphology, fertilization ability, and embryo implantation capacity. In this review, we highlight studies evaluating potential causes of abnormal protamine expression, including the sequencing of genes relevant to protamine expression in both affected patients and controls. While the variants of the protamine genes themselves do not appear to be responsible for most observed defects, variants of the Contrin gene, a transcription factor and translation repressor, appear to be contributory to some cases of abnormal expression. Additionally, we explore the potential effects of abnormal protamine replacement on the epigenome of human sperm. Ongoing studies are evaluating the role of retained histones and DNA methylation in sperm, which may be affected in sperm with aberrant protamine replacement. This important area of epigenetic research has profound clinical implications. [source] Characterization of human sperm N -acetylglucosaminidaseINTERNATIONAL JOURNAL OF ANDROLOGY, Issue 3 2008S. L. Perez Martinez Summary N -acetylglucosaminidase (NAG) is particularly active in mammalian spermatozoa and appears to be involved in fertilization. Although it is assumed that this enzyme is acrosomal, previous results from our laboratory suggest the presence of NAG at the sperm plasma membrane level. The present study attempted to analyse the subcellular distribution of this enzyme in human spermatozoa. Sperm were incubated under different conditions and NAG activity measured in the soluble extracts and cell pellets using a specific fluorometric substrate. A significant proportion of NAG activity was released when sperm were incubated in culture medium, suggesting a weak association with the plasma membrane. This location was confirmed by western blot analysis of plasma membrane fractions and immunofluorescence on non-permeabilized sperm, which showed a positive signal mainly on the acrosomal domain. The distribution of NAG activity between plasma membrane and acrosome was analysed after cell disruption by freezing and thawing. Triton X-100 stimulated sperm and epididymal NAG activity but not the enzyme obtained from other sources. In addition, biotinylated human recombinant NAG was able to bind to human sperm. Finally, after sperm incubation under capacitating conditions, NAG total activity increased and the sperm enzyme lost its ability to be stimulated by Triton X-100. The possible connection of these results with sperm maturation, capacitation and NAG participation in primary binding to the zona pellucida, was discussed. [source] The significance of platelet-activating factor and fertility in the male primate: a reviewJOURNAL OF MEDICAL PRIMATOLOGY, Issue 1 2005William E. Roudebush Abstract:, Since its discovery nearly 30 years ago platelet-activating factor (PAF) has emerged as one of the more important lipid mediators known. PAF (1- O -alkyl-2- O -acetyl- sn -glycero-3-phosphorylcholine) exists endogenously as a mixture of molecular species with structural variants of the alkyl moiety. PAF is a novel potent signaling phospholipid that has unique pleiotropic biological properties in addition to platelet activation. PAF also plays a significant role in reproduction and is present in the sperm of a number of primate species. PAF content in squirrel monkey sperm is significantly higher during the breeding season than the non-breeding season. PAF content in rhesus sperm has a significant relationship with sperm motility. PAF content in human sperm has a positive correlation with seminal parameters and pregnancy outcomes. The enzymes (lyso-PAF-acetyltransferase and PAF-acetylhydrolase) necessary for PAF activation and deactivation are present in primate sperm. PAF-acetylhydrolase may act as a ,decapacitation factor'. Removal of this enzyme during capacitation promotes PAF synthesis increasing primate motility and fertilization. PAF also plays a significant role in the fertilization process, enhancing the fertilization rates of oocytes. Enhanced embryo development has also been reported in oocytes fertilized with PAF-treated sperm. Exogenous PAF will also significantly improve primate artificial insemination pregnancy outcomes. PAF antagonists inhibit sperm motility, acrosome reaction, and fertilization thus suggesting the presence of receptors for PAF. The PAF-receptor is present on primate sperm, with altered transcript levels and distribution patterns on abnormal cells. Whereas, the exact mechanism of PAF in sperm function and reproduction is uncertain, its importance in normal primate fertility is substantial. [source] Relationship between fertilizing ability of ejaculated human spermatozoa and its chromatin heterogeneityJOURNAL OF OBSTETRICS AND GYNAECOLOGY RESEARCH (ELECTRONIC), Issue 2 2002Shinako Hashimoto Objective: The aim of this study was to examine the relationship between the fertilizing ability of ejaculated human sperm and its chromatin heterogeneity. Methods: We used the D-AO staining method (acridine orange epifluorescence accompanied by diamide, a thiol oxidizing agent) to analyze the sperm chromatin structure of infertile patients with IVF-ET treatment. SDS-PAGE was performed to analyze the sperm nuclear proteins collected from patients with immature sperm (stained red with D-AO staining) and proven fertile men. Results (1) It was suggested that D-AO staining allowed the immature sperm to be divided into two groups. One was immature sperm, which had disturbance of S-S formation in the epididymides, and the other was that which had an abnormal exchange process of nuclear proteins in the testes. (2) The stainability after D-AO staining showed no correlation with the findings of semen analysis. (3) The fertilization rate of IVF-ET was significantly correlated to the percentage of green sperm staining with D-AO staining. (4) In the pregnant group after IVF-ET, it was noticed that sperm of the green type with D-AO staining was increased in comparison with the non-pregnancy group. (5) The fertilization rate in the group of the sperm stained red with D-AO staining was increased to 73.5% by ICSI. (6) Definite differences were noticed between the protein components of the patients with immature sperm and those of the proven fertile men by analyzing with SDS-PAGE. Conclusion D-AO staining was an efficient method for evaluating the fertilizing ability of human ejaculated sperm, and to determine an appropriate ART tool such as ICSI. [source] Novel human testis-specific cDNA: Molecular cloning, expression and immunobiological effects of the recombinant proteinMOLECULAR REPRODUCTION & DEVELOPMENT, Issue 1 2001Ramasamy Santhanam Abstract A differential display-polymerase chain reaction was employed to obtain a testis-specific cDNA fragment. On screening the human testis-,gt10-cDNA library with testis-specific cDNA fragment, a novel cDNA encoding for a sperm antigen, designated TSA-1, was obtained. It has a novel open reading frame (ORF) of 471 base pairs encoding for 156 amino acids. The computer generated translated protein has a calculated molecular mass of 17.4 kDa and contains a potential N-glycosylation site at amino acids 122,124. The hydrophilicity analysis of the amino acid sequence suggested that this protein is a membrane-anchored peptide. Extensive analysis for tissue-specificity by Northern blots and RT-PCR-Southern blot procedures using various human tissues indicated that TSA-1 was specifically expressed only in the human testis. Based on the results of in vitro transcription and translation experiments, the TSA-1 (ORF) was subcloned into pGEX-6P-3 vector and expressed using the glutathione S -transferase gene fusion system. Antibodies (Ab) against the purified recombinant protein specifically recognized the ,17 kDa recombinant TSA-1, and a ,24 kDa band in human sperm extract in the Western blot procedure. The recombinant TSA-1 Ab recognized the acrosomal, equatorial, mid-piece, and tail regions of human sperm cell in indirect immunofluorescence, bound to live human sperm in the immunobeads binding technique (IBT) and caused a significant concentration-dependent inhibition of human sperm acrosome reaction. These findings indicate that the novel sperm-specific recombinant TSA-1 has a role in sperm function and may have applications in the development of a contraceptive vaccine, and in the specific diagnosis and treatment of male infertility. Mol. Reprod. Dev. 60: 1,12, 2001. © 2001 Wiley-Liss, Inc. [source] Cigarette smoking and aneuploidy in human spermMOLECULAR REPRODUCTION & DEVELOPMENT, Issue 4 2001Qinghua Shi Abstract Cigarette smoke contains chemicals which are capable of inducing aneuploidy in experimental systems. These chemicals have been shown to reach the male reproductive system, increasing oxidative DNA damage in human sperm and lowering semen quality. We have examined the association between smoking and aneuploid sperm by studying 31 Chinese men with similar demographic characteristics and lifestyle factors except for cigarette smoking. None of the men drank alcohol. These men were divided into three groups: nonsmokers (10 men), light smokers (<,20 cigarettes/day, 11 men), and heavy smokers (,,20 cigarettes/day, 10 men). There were no significant differences in semen parameters or in age across groups. Two multi-color fluorescence in situ hybridizations (FISH) were performed: two-color FISH for chromosomes 13 and 21, and three-color FISH for the sex chromosomes using chromosome 1 as an internal autosomal control for diploidy and lack of hybridization. The mean hybridization efficiency was 99.78%. The frequency of disomy 13 was significantly higher in light and heavy smokers than in non-smokers, while no significant differences in the frequency of disomy 21, X or Y were observed across groups. Significant inter-donor heterogeneity in every category of disomic sperm examined was found in both light and heavy smokers, while in nonsmokers only XY disomy showed significant inter-donor differences. Thus, we conclude that cigarette smoking may increase the risk of aneuploidy only for certain chromosomes and that men may have different susceptibilities to aneuploidy in germ cells induced by cigarette smoking. Mol. Reprod. Dev. 59: 417,421, 2001. © 2001 Wiley-Liss, Inc. [source] The Use of HOS Test to Evaluate Membrane Functionality of Boar Sperm Capacitated in vitroREPRODUCTION IN DOMESTIC ANIMALS, Issue 6 2002D Lechniak Contents The functional and structural integrity of sperm membrane are crucial for the viability of spermatozoa. The commonly used staining test (eosin + nigrosin) for assessing sperm membrane measures only its structural integrity. The hypoosmotic swelling test (HOS) originally developed for human sperm (Jeyendran et al. 1984) has been also applied to several species of domestic animals (bull, pig, horse, dog). The test enables to evaluate the functional status of the sperm membrane. The principle of HOS is based on water transport across the sperm tail membrane under hypoosmotic conditions. It has previously been used to assess the semen quality (Revell and Mrode 1994), to analyse fertilizing capacity (Rota et al. 2000; Perez-Llano et al. 2001) and also to detect viable, immotile cells for ICSI (Intra-cytoplasmic sperm injection) in human (Zeyneloglu et al. 2000). There are two procedures commonly used for sperm capacitation in the pig-sperm washing and incubation before insemination (Nagai 1994). Capacitation involves several changes like removing molecules coating the sperm head membrane, changes in membrane fluidity and intracellular ion concentration (Green and Watson 2001). Thus the membrane integrity as well as functionality may be affected as shown by Harrison (1996). The aim of the present study was to analyse changes in sperm membrane integrity after in vitro capacitation by use of the HOS test. [source] Effect of pH on the development of acrosomal responsiveness of human spermANDROLOGIA, Issue 2 2007N. L. Cross Summary Human sperm incubated in vitro gradually become responsive to inducers of the acrosome reaction. The roles of constituents of the incubation medium are not well understood. These experiments tested the effect of the extracellular pH on sperm acrosomal responsiveness. Sperm were incubated 24 h in media with pH varying between 6.7 and 7.6 and then exposed to progesterone to determine the number of sperm that had become acrosomally responsive. The number of responsive sperm was very low following incubation at pH 6.7,7.0, and increased with the pH over the range 7.0,7.6. Sperm incubated at low pH were not damaged as assessed by motility or viability, and if they were transferred to medium of high pH for 8 h, the inhibition of acrosomal responsiveness was reversed. Inhibition of acrosomal responsiveness at low pH was not due to impaired loss of sperm cholesterol, but was correlated with a reduced intracellular pH. The inhibition of acrosomal responsiveness by media of low pH may result from preventing the normal capacitation-related rise in intracellular pH. [source] Mature human spermatozoa do not transcribe novel RNAANDROLOGIA, Issue 2-3 2005S. Grunewald Summary Mature spermatozoa contain subsets of mRNA that have been found in human testes before. Based on this finding it was hypothesized that the mRNAs of spermatozoa are transcribed during spermatogenesis. However, up to now there is no proof of the transcriptional inactivity of human sperm. To address this issue we performed in vitro labelling experiments with radio-labelled uridine triphosphate followed by analysis of cellular RNA. There was virtually no radioactive RNA detectable in the RNA purified from human spermatozoa proving the transcriptional inactivity of mature spermatozoa. The spermatozoal RNA obviously results from transcription during spermatogenesis and can be used for diagnostic purposes. These findings might have diagnostic and , possibly , therapeutic value in infertility patients as spermatozoal RNAs might complement the RNA pool of the oocyte after fertilization. [source] | |||||||||||||