Showing papers on "Sperm plasma membrane published in 2010"
TL;DR: The results indicate diverse HSP chaperones are accessible for surface labelling on human sperm, and some share epitopes with C. trachomatis HSP70, suggesting an association between genital tract infection, immunity to H SP70 and reproductive failure.
132 citations
TL;DR: New insights into the pathophysiology of defective sperm function have clear implications for the diagnosis and treatment of male infertility, particularly with respect to the potential importance of antioxidant therapy.
Abstract: Infertility is a relatively common condition affecting approximately one in ten of the population In half of these cases, a male factor is involved, making defective sperm function the largest single, defined cause of human infertility Among other factors, recent data suggest that oxidative stress plays a major role in the etiology of this condition Spermatozoa spontaneously produce a variety of reactive oxygen species (ROS) including the superoxide anion, hydrogen peroxide and nitric oxide Produced in small amounts, ROS are functionally important in driving the tyrosine phosphorylation cascades associated with sperm capacitation However, when ROS production exceeds the spermatozoa’s limited antioxidant defenses, a state of oxidative stress is induced characterized by peroxidative damage to the sperm plasma membrane and DNA strand breakage in the sperm nucleus Such oxidative stress not only disrupts the fertilizing potential of human spermatozoa but also the ability of these cells to create a normal healthy embryo As a result, DNA damage in human spermatozoa is correlated with an increased incidence of miscarriage and various kinds of morbidity in the offspring These insights into the pathophysiology of defective sperm function have clear implications for the diagnosis and treatment of male infertility, particularly with respect to the potential importance of antioxidant therapy These concepts may also be relevant to the design of novel approaches to male contraception that attempt to replicate the pathological situation
84 citations
TL;DR: Observations show that PDC-109 functions as a molecular chaperone in vitro, suggesting that it may assist the proper folding of proteins involved in the bovine sperm capacitation pathway.
Abstract: The major protein of bovine seminal plasma, PDC-109, binds to choline phospholipids on the sperm plasma membrane and induces the efflux of cholesterol and choline phospholipids, which is an important step in sperm capacitation. The high abundance, polydisperse nature and reversibility of thermal unfolding of PDC-109 suggest significant similarities to chaperone-like proteins such as spectrin, alpha-crystallin, and alpha-synuclein. In the present study, biochemical and biophysical approaches were employed to investigate the chaperone-like activity of PDC-109. The effect of various stress factors such as high temperature, chemical denaturant (urea), and acidic pH on target proteins such as lactate dehydrogenase, alcohol dehydrogenase, and insulin were studied in both the presence and absence of PDC-109. The results obtained indicate that PDC-109 exhibits chaperone-like activity, as evidenced by its ability to suppress the nonspecific aggregation of target proteins and direct them into productive folding. Atomic force microscopic studies demonstrate that PDC-109 effectively prevents the fibrillation of insulin, which is of considerable significance since amyloidogenesis has been reported to be a serious problem during sperm maturation in certain species. Binding of phosphorylcholine or high ionic strength in the medium inhibited the chaperone-like activity of PDC-109, suggesting that most likely the aggregation state of the protein is important for the chaperone function. These observations show that PDC-109 functions as a molecular chaperone in vitro, suggesting that it may assist the proper folding of proteins involved in the bovine sperm capacitation pathway. To the best of our knowledge, this is the first study reporting chaperone-like activity of a seminal plasma protein.
55 citations
TL;DR: Exposure to the lower molecular fraction significantly inhibited, but did not abolish, the bicarbonate-induced stimulation of motility, and the results show that subpopulations of spermatozoa respond differentially to oviductal fluid, and suggest that exposure to oVIDUCTal fluid in vivo could exert a further level of functional sperm selection.
53 citations
TL;DR: This work uses complementation assays to define major functional regions of the Arabidopsis thaliana ortholog using HAP2(GCS1) variants with modifications to regions amino(N) and carboxy(C) to its single transmembrane domain and suggests that the N-terminus functions by interacting with female gamete-expressed proteins and that the positively charged C-termini may function through electrostatic interactions with the sperm plasma membrane.
Abstract: HAP2(GCS1) is a deeply conserved sperm protein that is essential for gamete fusion. Here we use complementation assays to define major functional regions of the Arabidopsis thaliana ortholog using HAP2(GCS1) variants with modifications to regions amino(N) and carboxy(C) to its single transmembrane domain. These quantitative in vivo complementation studies show that the N-terminal region tolerates exchange with a closely related sequence, but not with a more distantly related plant sequence. In contrast, a distantly related C-terminus is functional in Arabidopsis, indicating that the primary sequence of the C-terminus is not critical. However, mutations that neutralized the charge of the C-terminus impair HAP2(GCS1)-dependent gamete fusion. Our results provide data identifying the essential functional features of this highly conserved sperm fusion protein. They suggest that the N-terminus functions by interacting with female gamete-expressed proteins and that the positively charged C-terminus may function through electrostatic interactions with the sperm plasma membrane.
47 citations
TL;DR: The presence of SAP on the surface of mature sperm implies that SAP has a physiological role in reproduction, which is thought to be in the removal of spermatozoa from the female genital tract via phagocytosis.
Abstract: Background
The precise composition of the human sperm plasma membrane, the molecular interactions that define domain specific functions, and the regulation of membrane associated proteins during the capacitation process, still remain to be fully understood. Here, we investigated the repertoire of calcium-regulated proteins associated with the human sperm plasma membrane.
38 citations
TL;DR: Results show that whole-body heat exposure to 37 degrees C-38 degrees C induces membrane changes in the epididymal spermatozoa of mice, which may lead to apoptosis.
Abstract: This study was carried out to determine if exposure to hot environmental temperatures had a direct, detrimental effect on sperm quality. For this the effect of whole-body heat exposure on epididymal spermatozoa of laboratory mice was investigated. C57BL/6 mice (n = 7) were housed in a microclimate chamber at 37°C–38°C for 8 h per day for three consecutive days, while control mice (n = 7) were kept at 23°C–24°C. Cauda epididymal spermatozoa were obtained 16 h after the last heat treatment. The results showed that sperm numbers were similar in the two groups (P = 0.23), but after heat treatment, a significant reduction in the percentage of motile sperm was present (P < 0.0001). Membrane changes of the spermatozoa were investigated by staining with phycoerythrin (PE)-conjugated Annexin V, which detects exteriorization of phosphotidylserine from the inner to the outer leaflet of the sperm plasma membrane, and 7-aminoactinomycin D (7-AAD), which binds to the sperm nucleus when the plasma membrane is damaged. The percentage of spermatozoa showing positive staining with Annexin V–PE or 7-AAD or both, was significantly higher (P < 0.05) in heat-exposed mice compared with controls. These results show that whole-body heat exposure to 37°C–38°C induces membrane changes in the epididymal spermatozoa of mice, which may lead to apoptosis.
26 citations
TL;DR: The findings indicate that, among the different fractions, the hexane fraction of the hydroethanolic extracts of the two plants produced the most effective spermicidal activity and can be considered as vaginal contraceptive.
24 citations
TL;DR: Powdered egg yolk may be used in an extender for the cryopreservation of Zebu bull spermatozoa and sperm motility and viability were significantly higher after thawing in the extender containing powdered Egg yolk.
22 citations
TL;DR: MSA is a potent spermicidal molecule that may be explored further for its suitability as an effective component of vaginal contraceptive.
Abstract: The seed extracts of Madhuca latifolia were reported to have spermicidal activity. The current investigation identified the spermicidal component of the extracts and evaluated its spermicidal potential in vitro. As characterized by infrared, mass, and nuclear magnetic resonance (NMR) spectral analyses, Mi-saponin A (MSA) was found to be the most potent component among a mixture of saponins. The mean effective concentrations of MSA that induced irreversible immobilization were 320 μg/mL for rat and 500 μg/mL for human sperm, as against the respective concentrations of 350 and 550 μg/mL of nonoxynol 9 (N-9). The mode of spermicidal action was evaluated by a battery of tests including (a) double fluoroprobe staining for sperm viability, (b) hypoosmotic swelling test and, assays for 5’ nucleotidase and acrosin for physiological integrity of sperm plasma membrane, (c) scanning and transmission electron microscopy for sperm membrane ultrastructure, and (d) plasma membrane lipid peroxidation (LPO). The observations, taken together, were interpreted to mean that the spermicidal effect of MSA involved increased membrane LPO leading to structural and functional disintegration of sperm plasma membrane and acrosomal vesicle. A comparative in vitro cytotoxicity study in human vaginal keratocyte (Vk2/E6E7) and endocervical (End/E6E7) cell lines demonstrated that the 50% cell cytotoxicity (CC50) values, and consequently the safety indices, for MSA were ≥ 8-fold higher as compared to those of N-9. In conclusion, MSA is a potent spermicidal molecule that may be explored further for its suitability as an effective component of vaginal contraceptive.
21 citations
TL;DR: The findings confirmed that the boar sperm aging changes, which increased during liquid semen preservation, were connected with the loss of function and integrity of the sperm plasma membrane.
Abstract: Studies were performed on boar semen routinely used at the local artificial insemination (AI) centre. The semen was stored in a Safe Cell Plus commercial extender at 17 °C for nine days. The aim of our research was focused on changes in sperm plasma membrane integrity. The integrity of the sperm plasma membrane and acrosome as well as sperm motility decreased after dilution and during storage of the semen. The highest percentage of live sperm was identified by the eosin-nigrosin method, a lower percentage by the SYBR-14/PI test, and the lowest percentage of live cells was discovered by the hypoosmotic swelling (HOS) test (P < 0.01). There were significant differences between the results of staining methods and sperm motility (P < 0.01). No significant differences were found between the HOS test results and sperm motility. The plasma membrane integrity parameters positively correlated (P < 0.001) with each other and with sperm motility but negatively with aspartate aminotransferase activity. Our findings confirmed that the boar sperm aging changes, which increased during liquid semen preservation, were connected with the loss of function and integrity of the sperm plasma membrane. The employed complementary tests are comprehensive indicators of sperm membrane integrity during long-term semen preservation, and they can help establish the actual number of ‘healthy’ cells. The assays may be used in AI laboratories and should be incorporated into the routine of semen analysis.
TL;DR: The results indicate a possible functional compartmentalization of PMCA in bull sperm membranes and point to a presumptive, yet unknown interaction partner of Ca(2+) -ATPase and PDC-109, mediating the P DC-109 action from DRMs to the DS fraction of sperm plasma membrane.
Abstract: The plasma membrane Ca(2+) -ATPase (PMCA) is the main restorer of Ca(2+) balance in sperm. Particularly, PMCA isoform 4 has an essential function in sperm fertility by its participation in gaining sperm hypermotility. PMCA activity is influenced by its lipid environment. Sperm membranes exhibit lipid raft microdomains or detergent-resistant membrane domains, enriched in sphingolipids and cholesterol, forming functional specialized areas. Lipid and protein composition of lipid rafts alters during the capacitation process, which is characterized by a cholesterol efflux. In this study, the localization of PMCA4 in lipid membrane fractions of the sperm plasma membrane was investigated. We identified PMCA4 in both the detergent-resistant membrane (DRM) and in the detergent-soluble (DS) fraction of caput and cauda sperm, respectively. Capacitation did not influence PMCA4 localization. In immunocytochemical studies PMCA4 was co-localized with the lipid raft/DRM marker caveolin in the mid piece of caput and cauda sperm. Functional studies with seminal vesicle major protein PDC-109 showed that the Ca(2+) -ATPase activity in DS fractions of cauda sperm and capacitated cauda sperm was stronger enhanced than in the DRMs. In both fractions the effect was statistically significant. In contrast, in lipid overlay experiments PDC-109 interacted stronger with the lipids extracted from DRMs than with lipids extracted from DS. Our results indicate a possible functional compartmentalization of PMCA in bull sperm membranes and point to a presumptive, yet unknown interaction partner of Ca(2+) -ATPase and PDC-109, mediating the PDC-109 action from DRMs to the DS fraction of sperm plasma membrane.
TL;DR: The experimental strategy described here can be applied to investigate the interaction of soluble proteins with membranes in order to understand the physiological role of PDC-109 in sperm cell maturation.
Abstract: Methods are described that have been used for characterizing the interaction of the soluble bovine seminal plasma protein PDC-109 with liposomes. PDC-109 binds to bull sperm cells upon ejaculation and is an important modulating factor of sperm cell maturation. The binding of the protein to sperm cells is mediated via lipids of the sperm plasma membrane. Most of our current knowledge about the molecular mechanisms of PDC-109-membrane interaction has been obtained by studies employing lipid vesicles. The experimental strategy described here can be applied to investigate the interaction of soluble proteins with membranes in order to understand their physiological role.
TL;DR: The protocol demonstrated here can be used to efficiently produce transgenic Xenopus laevis embryos that can be analyzed without any need to breed to the next generation, allowing for efficient and rapid generation of transgenic embryos for analyses of promoter and gene function.
Abstract: Stable integration of cloned gene products into the Xenopus genome is necessary to control the time and place of expression, to express genes at later stages of embryonic development, and to define how enhancers and promoters regulate gene expression within the embryo. The protocol demonstrated here can be used to efficiently produce transgenic Xenopus laevis embryos. This transgenesis approach involves three parts: 1. Sperm nuclei are isolated from adult X. laevis testis by treatment with lysolecithin, which permeabilizes the sperm plasma membrane. 2. Egg extract is prepared by low speed centrifugation, addition of calcium to cause the extract to progress to interphase of the cell cycle, and a high-speed centrifugation to isolate interphase cytosol. 3. Nuclear transplantation: the nuclei and extract are combined with the linearized plasmid DNA to be introduced as the transgene and a small amount of restriction enzyme. During a short reaction, egg extract partially decondenses the sperm chromatin and the restriction enzyme generates chromosomal breaks that promote recombination of the transgene into the genome. The treated sperm nuclei are then transplanted into unfertilized eggs. Integration of the transgene usually occurs prior to the first embryonic cleavage such that the resulting embryos are not chimeric. These embryos can be analyzed without any need to breed to the next generation, allowing for efficient and rapid generation of transgenic embryos for analyses of promoter and gene function. Adult X. laevis resulting from this procedure also propagate the transgene through the germline and can be used to generate lines of transgenic animals for multiple purposes.
TL;DR: To analyze sperm surface molecules involved in sperm–egg envelope binding in Xenopus laevis, heat‐solubilized vitelline envelope (VE) dot blotted onto a polyvinylidene difluoride (PVDF) sheet was incubated with a detergent extract of sperm plasma membrane (SP‐ML).
Abstract: To analyze sperm surface molecules involved in sperm-egg envelope binding in Xenopus laevis, heat-solubilized vitelline envelope (VE) dot blotted onto a polyvinylidene difluoride (PVDF) sheet was incubated with a detergent extract of sperm plasma membrane (SP-ML). The membrane components bound to the VE were detected using an antibody library against sperm plasma membrane components, and a hybridoma clone producing a monoclonal antibody (mAb) 16A2A7 was identified. This mAb was used in a Far Western blotting experiment in which VE was separated by electrophoresis, and then transferred to a PVDF strip that was incubated with SP-ML. It was found that SP-ML binds to the VE component gp37 (Xenopus homolog of mammalian ZP1). The antigens reactive to mAb 16A2A7 showed apparent molecular weights of 65-130 and 20-30 kDa, and were distributed relatively evenly over the entire sperm surface. Periodate oxidation revealed that both the pertinent epitope on the sperm surface and the ligands of VE gp37 were sugar moieties. VE gp37 was exposed on the VE surface, and the mAb 16A2A7 dose-dependently inhibited sperm binding to VE. The sperm membrane molecules reactive with mAb 16A2A7 also reacted with mAb 2A3D9, which is known to recognize the glycoprotein SGP in the sperm plasma membrane and is involved in interactions with the egg plasma membrane, indicating that the sperm membrane glycoprotein has a bifunctional role in Xenopus fertilization.
01 Jan 2010
TL;DR: In this article, the authors showed that the addition of various antioxidants in extender can improve the quality of frozen semen of various animals, such as mice, rats, and humans.
Abstract: THE ROLE OF ANTIOXIDANT FOR IMPROVING THE QUALITY OF FROZEN SEMEN The quality of frozen semen will be reduced if high oxidative metabolism activity in semen occurs, due to the formation of free radical compounds causing lipid peroxidation reaction on sperm plasma membrane. Lipid peroxidation occurs due to the exposure of semen to the oxygen during handling. Lipid peroxidation can be prevented by the addition of antioxidant compounds such as vitamin C, vitamin E, glutathione, and β-carotene, in the semen extender. Results of some researches showed that the addition of various antioxidans in extender can improve the quality of frozen semen of various animals.
Journal Article•
TL;DR: This review presents an update on the principles, methods and steps of the detection of sperm plasma membrane function, as well as an overview of its status quo and application.
Abstract: The sperm plasma membrane is rich in polyunsaturated fatty acids and a variety of proteins, and its function is associated with sperm capacitation, acrosome reaction and sperm-egg fusion. Sperm fertilizability can be predicted by detecting the function of the sperm plasma membrane, which is performed mainly with the following five techniques: sperm hypoosmotic swelling test, Eosin gamma water test, sperm membrane lipid peroxidation determination, seminal plasma superoxide dismutase determination, and flow cytometry. The evaluation of the function of sperm plasma membrane can be applied in detecting semen quality, selecting semen centrifugation, assessing the quality and fertilizability of sex-sorted sperm, improving cryopreservation, and guiding the optimization of intracytoplasmic sperm injection. This review presents an update on the principles, methods and steps of the detection of sperm plasma membrane function, as well as an overview of its status quo and application.
10 May 2010
TL;DR: The cigarette smoking have several impacts on sperm functions and integrity of plasma membrane, as well as sperm fertilizing ability, which demonstrated that the sperm parameters, HOS-test and IUI outcomes for non smoker infertile males was higher than smokers.
Abstract: The present study was designed to assess the effect of cigarette smoking on semen parameters, hypo-osmotic swelling (HOS) test (%) and outcome of intra-uterine insemination (IUI). In this study, one hundred infertile males were involved and according to cigarette smoking were divided into 55 smokers and 45 non smoker infertile couples. From each male, semen samples were collected and the sperm parameters including sperm concentration, sperm motility, progressive sperm motility, normal sperm morphology, and HOS-test were evaluated according to standard World Health Organization (WHO) criteria. For IUI, the sperm prepared using direct swim-up technique through incubation for 30 minute in 5% CO 2 at 37oC. The results of the present study demonstrated that the sperm parameters, HOS-test (%) and IUI outcomes for non smoker infertile males was higher than smokers. In addition, the results of sperm parameters and HOS-test (%) for smokers were more deviated from normal range of criteria of WHO than non smokers. Non significant differences (P>0.05) in the sperm HOS-test were assessed between non smokers and smokers. From the results of the present study, it was concluded that the cigarette smoking have several impacts on sperm functions and integrity of plasma membrane, as well as sperm fertilizing ability. Further studies are recommended to assess the effect of cigarette smoking on DNA damage and embryo quality after IVF-ET.
DOI•
01 Sep 2010
TL;DR: The quality of frozen semen will be reduced if high oxidative metabolism activity in semen occurs, due to the formation of free radical compounds causing lipid peroxidation reaction on sperm plasma membrane as mentioned in this paper.
Abstract: The quality of frozen semen will be reduced if high oxidative metabolism activity in semen occurs, due to the formation of free radical compounds causing lipid peroxidation reaction on sperm plasma membrane Lipid peroxidation occurs due to the exposure of semen to the oxygen during handling Lipid peroxidation can be prevented by the addition of antioxidant compounds such as vitamin C, vitamin E, glutathione, and b-carotene, in the semen extender Results of some researches showed that the addition of various antioxidans in extender can improve the quality of frozen semen of various animals Key words: Antioxidant, free radical, lipid peroxidation, frozen semen
Journal Article•
TL;DR: SYBR-14/PI dual fluorescent staining and flow cytometry could be readily used to detect sperm PMI and evaluate male reproductivity.
Abstract: OBJECTIVE To investigate the feasibility and clinical significance of detecting the plasma membrane integrity (PMI) of sperm by SYBR-14/PI fluorescent staining and flow cytometry. METHODS A total of 208 semen samples were divided into a normal (n = 31) and an abnormal group (n = 177), subjected to conventional computer-assisted semen analysis (CASA), and then evaluated for sperm PMI by flow cytometry after washed and SYBR-14/PI dual fluorescent staining. The percentage of sperm with PMI was indicated as that of the sperm emitting green fluorescence (SYBR-14+/PI- %). RESULTS Significant differences were detected in SYBR-14+/PI- and SYBR-14-/PI+ between the normal and abnormal groups (P < 0.05), with the SYBR-14+/PI- % significantly higher in the former ([55.66 +/- 20.64] %) than in the latter ([39.71 +/- 19.21] %) (P = 0.000). The SYBR-14+/PI-% showed significant positive correlations with sperm motility (r = 0.408, P = 0.000) and the percentage of grade a + b sperm (r = 0.398, P = 0.000), and a significant negative correlation with the percentage of grade d sperm (r = -0.413, P = 0.000); the SYBR-14-/PI+ % exhibited significant negative correlations with sperm motility (r = -0.380, P = 0.000) and the percentage of grade a + b sperm (r = -0.397, P = 0.000), and a significant positive correlation with the percentage of grade d sperm (r = 0.385, P = 0.000); the SYBR-14+/PI+ % showed positive correlations with sperm motility (r = 0.172, P = 0.013) and the percentage of grade a + b sperm (r = 0.177, P = 0.011), and a negative correlation with grade d sperm (r = -0.164, P = 0.018). CONCLUSION SYBR-14/PI dual fluorescent staining and flow cytometry could be readily used to detect sperm PMI and evaluate male reproductivity.
01 Jan 2010
TL;DR: In this article, the most effective fraction of the hydroethanolic (water:ethanol, 1:1) extracts of Stephania hernandifolia leaves and Achyranthes aspera roots (in a composite manner at a ratio of 1:3, respectively) that will provide maximum spermicidal activity in human and rat spermatozoa was determined.
Abstract: Background: This study was conducted to determine the most effective fraction of the hydroethanolic (water:ethanol, 1:1) extracts of Stephania hernandifolia leaves and Achyranthes aspera roots (in a composite manner at a ratio of 1:3, respectively) that will provide maximum spermicidal activity in human and rat spermatozoa out of five different ratios (1:1, 1:3, 1:7, 3:1 and 7:1) that have been studied in pilot experiments. Study Design: n-Hexane, chloroform and ethyl acetate fractions of the hydroethanolic (1:1) extracts of S. hernandifolia and A. aspera were mixed at 1:3. Different concentrations were tested for sperm immobilization, sperm viability, acrosome status, 5′-nucleotidase activity and nuclear chromatin decondensation using human and rat spermatozoa for the selection of the most effective concentration. Results: Out of three fractions of the hydroethanolic (1:1) extracts of the said plants, the n-hexane fraction was most effective, and the chloroform fraction exhibited minimum activity for this purpose. At a concentration of 0.1 g/mL hexane fraction, all sperm of the human sample were immobilized immediately (within 20 s). In case of the rat sample, all epididymal spermatozoa were immobilized immediately (within 20 s) by treatment with hexane fraction at a concentration of 0.004 g/mL. All human sperm were found to be nonviable within 20 min. The activity of acrosome enzymes was reduced, and significant release of 5′-nucleotidase (a plasma membrane marker) into the surrounding medium was noted after treatment with 0.1 g/mL hexane fraction, indicating that the hexane fraction affected the cytoarchitecture of the sperm plasma membrane. The maximum number of human sperm failed to decondense when treated with 0.1 g/mL hexane fraction, and sperm motility was also irreversible. The hexane fraction was tested in rats as vaginal contraceptive and showed 100% efficacy, indicating its potential for development as vaginal contraceptive. Conclusion: The findings indicate that, among the different fractions, the hexane fraction of the hydroethanolic extracts of the two plants produced the most effective spermicidal activity and can be considered as vaginal contraceptive.
TL;DR: Fertilization of Drosophila subobscura is examined using anti-sperm surface � -N- acetylhexosaminidases and � -L-fucosidase antibodies and short and long sperm are functionally equivalent.
Abstract: Drosophila obscura group species produce two distinct sizes of nucleated sperm that differ only in head and tail lenghts. Between both sperm there is no differences in location of the acrosome and flagellum during spermiogenesis where each sperm type develops in its own bundle. Fertile sperm accumulate in the seminal vesicles. Fertilization is ex- clusively monospermic and in a previous study we suggested that both types of sperm are fertilization-competent on the basis of similar DNA content and storage in females also if morph variations are consistent with a fertilization-related se- lection for optimal sperm size. This assumption is in agreement with previous studies that demonstrated that only long sperm fertilize eggs. In this study fertilization of Drosophila subobscura is examined using anti-sperm surface � -N- acetylhexosaminidases and � -L-fucosidase antibodies. Beta hexosaminidases are intrinsic proteins of the sperm plasma membrane in spermomomorphic species of the melanogaster group closely related to Drosophila melanogaster. These enzymes had been previously identified as putative receptors for glycoconjugates of the egg surface, structurally and func- tionally conserved. Here their localization has been investigated in Drosophila subobscura. Consistent with our previ- ous study, short and long sperm are functionally equivalent. More data are needed to clarify the consequences and adapta- tive significance of morph variations.
01 Jan 2010
TL;DR: Capacitation is the reaction, which includes all of the molecular and physiological events of mature sperm to gain the ability of fertilizing oocytes at metaphase 2 in the female genital tract, and acquires the ability to penetrate the corona radiata and to bind to the zona pellucida.
Abstract: Male and female gamets are derived from the primordial germ cells, which migrate from the wall of the yolk sac toward the developing gonads. Following a series of mitotic divisions these cells increase in number at the gonads. The primordial germ cells differentiate into spermatogonia and take the form of mature spermatozoa after spermotogensis and spermotogenesis at puberty. Capacitation is the reaction, which includes all of the molecular and physiological events of mature sperm to gain the ability of fertilizing oocytes at metaphase 2 in the female genital tract. Some molecular events significant in the initiation of capacitation have been identified as cholesterol efflux from the sperm plasma membrane, increased membrane fluidity, modulation of intracellular ion concentration, hyperpolarization of the sperm plasma membrane and increased protein tyrosine phosphorylation. During capacitation, the spermatozoa acquires the ability to penetrate the corona radiata and to bind to the zona pellucida. This binding triggers acrosome reaction which occurs by the development of multiple fenestrations between the outer acrosomal membrane and the plasma membrane of the spermatozoon. After the fusion of oocyte and sperm plasma membranes, sperm and oocyt pronuclei are joined together to compose the zygote.