Sperm plasma membrane

About: Sperm plasma membrane is a research topic. Over the lifetime, 1016 publications have been published within this topic receiving 49964 citations.

Proteomic characterization of human sperm plasma membrane-associated proteins and their role in capacitation.

Abstract: Background Plasma membranes of ejaculated sperm are covered by epididymal and accessory glands secreted proteins that must be released from sperm surface during the female reproductive tract passage in order to capacitate and fertilize the oocyte. Objectives As human sperm plasma membrane-associated proteins (SMAP) have not yet been investigated, the aim of this study was to characterize the SMAP released during in vitro human capacitation and to study their possible role as decapacitation factors. Materials and methods SMAP were characterized by 2-dimensional electrophoresis and mass spectrometry analysis. Besides, we explored SMAP effects on motility, protein tyrosine phosphorylation, and calcium ionophore-induced acrosome reaction of spermatozoa either incubated for 6 h in capacitating medium ± SMAP or for 5 h in capacitating medium alone followed by incubation for 1 h ± SMAP. Results Mass spectrometry analysis allowed the identification of 29 proteins, all of which have previously been identified in the human seminal fluid. Spermatozoa incubated for 6 h under capacitating conditions in the presence of the SMAP showed a significant decrease in the incidence of non-progressive motility, hyperactivation, protein tyrosine phosphorylation, and calcium ionophore-induced acrosome reaction. However, spermatozoa incubated for 5 h in capacitating medium and further incubated for 1 h with the SMAP showed a lower percentage of spermatozoa with non-progressive motility and hyperactivated cells but no effects on protein tyrosine phosphorylation were detected. Discussion and conclusions Our results indicate that SMAP inhibit the progress of human sperm capacitation, but only motility changes related to capacitation may be reversed by these proteins. The study of the identified proteins on sperm function and their mechanisms of action on this cell may contribute to the understanding of their role during capacitation.

Analysis of a sperm surface molecule that binds to a vitelline envelope component of Xenopus laevis eggs.

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.

Original research article Search for a potent microbicidal spermicide from the isolates of Shorea robusta resin

Abstract: Background: An alarming increase in global population is the root cause of poverty, malnutrition, sexually transmitted infections (STIs) and many other social problems. Microbicidal spermicides possessing dual function of contraception and STI protection can effectively combat this problem, and their development is of utmost importance at present. Study Design: A major metabolite isolated from Shorea robusta resin was spectroscopically characterized as asiatic acid. Spermicidal efficacy of the isolate was evaluated in vitro by a modified Sander–Cramer test. The mode of spermicidal action was assessed by (a) double fluoroprobe staining, (b) hypoosmotic swelling test and (c) scanning electron microscopy. Antimicrobial efficacy was assessed by disc diffusion and broth dilution methods using human isolates of bacteria (Escherichia coli ATCC 25938 and Pseudomonas aeruginosa 71) and fungus (Candida tropicalis). Results: The minimum effective concentration of asiatic acid that induced instantaneous immobilization of rat spermatozoa in vitro was 125 mcg/mL. The mechanism of action involved disruption of sperm plasma membrane. The microbicidal efficacy was found to be moderate for vaginal pathogens, with no effect on normal vaginal flora. Conclusion: Asiatic acid possesses appreciable spermicidal and microbicidal potential and may be explored as an effective microbicidal spermicide.

Ghrelin enhances viability of rat spermatozoa during incubation at 37°C

Abstract: Summary Antioxidant properties of ghrelin have been demonstrated in recent studies. In the present study, the effects of chronic administration of ghrelin on the motility and plasma membrane integrity of rat spermatozoa during incubation at 37oC were investigated. Thirty 45-day-old male Wistar rats were divided into control and treatment groups. Rats in the treatment group were daily injected subcutaneously with 1 nmol of ghrelin for 10 consecutive days and the control rats received normal saline. Sperm was collected after killing of rats on days 5, 15 and 40 after the last injection, and sperm characteristics were examined at 0, 3 and 5 h after incubation at 37oC. Mass motility and forward progressive movement of spermatozoa were significantly higher in ghrelin-treated animals at 3 and 5 h of incubation on day 5 (P<0.05). After 3 h of incubation on day 15, only mass motility was greater than that of the control group. Plasma membrane integrity was assessed by hypoosmotic swelling (HOS) “water test”. The mean value of HOS reacted spermatozoa was higher in the treatment group on days 5 and 15 during 0, 3 and 5 h of incubation (P<0.05). However, the percentage of HOS-positive spermatozoa was not significantly different on day 40 between groups. There was a high correlation at 3 and 5 h of day 5 between the forward progressive movement (r = 0.92 and 0.94, P<0.0001) as well as overall sperm motility (r = 0.78 and 0.81, P<0.01) with HOS test in the ghrelin-treated animals. These results can be attributed to the antioxidative effects of ghrelin on the rat sperm especially on its plasma membrane which probably protects the sperm plasma membrane against oxidative damage during incubation and causes subsequent significant increase in the HOS test results. This may result in higher sperm motility index during 5 h of incubation.