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.

Partial purification and characterization of a phosphoprotein phosphatase from sperm plasma membrane.

Abstract: A phosphoprotein phosphatase (PPase M-I) that dephosphorylates serine and threonine residues of histones was isolated from the goat cauda-epididymal sperm plasma membrane and partially characterized. The PPase was solubilized from the sperm membrane by treating it with 0.1 N NaOH at pH 11.4 and the solubilized enzyme was partially purified by concanavalin A-sepharose affinity chromatography and high-performance liquid chromatography (HPLC), revealing it to be a 520-kDa protein. The PPase gave a single protein band in native polyacrylamide gel electrophoresis (PAGE), but in the presence of SDS it resolved into multiple proteins (35–170 kDa) showing that the isolated enzyme contained a few contaminating proteins. The enzyme is a glycoprotein because it binds with high affinity to concanavalin A. It was maximally active at pH 8.0 and its activity was not dependent on bivalent metal ions. The enzyme is a specific phosphatase as it displayed higher affinity for dephosphorylation of large molecular weight phosphate esters. The PPase showed broad substrate specificity for the dephosphorylation of a variety of proteins. The membrane-associated PPase was strongly (70–80%) inhibited by detergents (0.5%) such as Nonidet P-40, Lubrol PX, Triton X-100 and Tween-20. Pyrophosphate (5 mM) and orthovanadate (400 M) had no significant effect on the activity of the isolated PPase whereas polyamines such as spermine (10 mM) nd spermidine (10 mM) slightly inhibited (20%) the enzymatic activity. Inorganic phosphate (10 mM) and NaF (10 mM), the well-known inhibitors of the cytosolic PPases, had no appreciable effect on the activity of PPase M-I, indicating that the membrane-bound PPase is distinct from the cytosolic PPases. The enzyme was radiolabelled when the intact spermatozoa were subjected to lactoperoxidase-mediated radioiodination reaction. The results show that the PPase M-I is an ecto-enzyme that may play an important role in sperm physiology by causing the dephosphorylation of the sperm outer surface phosphoproteins.

Correlation between creatine kinase activity, lipid-peroxidation and water test in male infertility.

Abstract: New approaches need to be pursued towards the assessment of sperm quality using biochemical markers. In order to help develop a good biochemical marker to assess sperm-membrane integrity, the enzyme creatine kinase (CK) was studied in semen of normal, oligospermic and azoospermic samples and correlated with sperm concentration, lipid-peroxidation (LP) and water test. Presence of isoforms of creatine kinase (CK-MB) was also seen. An inverse correlation was observed between CK activity and sperm concentration (p<0.001). Water test was seen to be inversely correlated with CK activity (p<0. 001). Lipid peroxidation showed positive correlation with CK activity (p<0.001). A significant correlation between loss of sperm function meditated by induction of peroxidative damage to sperm plasma membrane is indicated. Enzymes like CK can serve as good biochemical marker along with lipid peroxidation to confirm loss of sperm membrane integrity. The water test can be used as a preliminary screening test for sperm membrane integrity.

Seminal coagulation and sperm quality in different social contexts in captive tufted capuchin monkeys (Sapajus apella).

Abstract: In the present study, we aimed to assess the influence of different social contexts on the seminal coagulation and sperm quality in captive tufted capuchin monkeys. For this, males were housed either individually, in mixed-sex groups (with females), or in male-only groups. Monkeys were housed in cages and each cage type (i.e., individual or group cage) was placed in a different room. Forty-one males were subjected to semen collection by rectal electroejaculation. The degree of seminal coagulation was determined on a scale of I-IV. Seminal volume, sperm concentration, sperm motility, vigor, and plasma membrane integrity were evaluated for all ejaculate samples. All ejaculates collected showed degrees of coagulation between II and IV, where the majority presented coagulation degree IV, when collected from animals housed in groups. No statistical differences among percentages of coagula degree when samples were collected from males housed individually. Animals housed in group cages (male-only groups and mixed-sex groups) showed a significantly higher percentage of ejaculates at degree IV than males housed individually. Seminal volume was not affected by the coagula degree but by the housing system, where animals housed individually showed the highest volume (543 μl) when compared with those animals from male (273 μl) and mixed-sex (318 μl) groups. No differences were observed in semen volume when comparing male-only groups with mixed-sex groups. Sperm motility was affected by both housing system and coagula degree. Samples with coagula degree IV from animals housed individually showed the highest (72%) sperm motility percentages. Sperm plasma membrane integrity was lower when samples were presenting coagula degree II + III and collected from male- (17%) or mixed-sex (23%) groups. However, this housing system effect was not observed when sperm was obtained from coagula degree IV semen. Sperm vigor was neither affect by housing system or coagula degree.

Increasing Extender Viscosity Improves the Quality of Cooled Boar Semen

Abstract: The use of several types of gelling extenders for the storage of semen from several domestic species in the solid state has been shown to have beneficial effects on some semen quality parameters. The objective of this study was to evaluate the effect of a new high-viscosity semen extender, Zoosperm ND-5 3D ® (Import-Vet, Centelles, Spain), on the the quality of boar spermatozoa at preserved at 17oC for 7 days. Sodium alginate was used for the first time to increase the viscosity of the extender for the liquid storage of boar semen. The same extender, but without increased viscosity, was used as a control extender (Zoosperm ND-5 ® , Import-Vet, Centelles, Spain). Sixteen ejaculates from four Pietrain boars were evaluated for motility (by the CASA system), and for viability, acrosome status, plasma membrane fluidity, externalization of phosphatidylserine at the plasma membrane of the spermatozoa and mitochondrial membrane potential (by flow cytometry). In samples diluted with the Zoosperm ND-5 3D ® viscous extender, the STR (straightness) parameter and the number of progressively motile spermatozoa were higher compared to those of the non-viscous extender (p < 0.05). In addition, the number of spermatozoa with damaged acrosomes, an unstable sperm plasma membrane and externalization of phosphatidylserine at the plasma membrane was lower in samples treated with the viscous extender (p < 0.05). In conclusion, an increase in extender viscosity improves quality of boar spermatozoa following long-term storage.

Bactericidal/permeability-increasing protein originates in both the testis and the epididymis and localizes in mouse spermatozoa.

Abstract: Bactericidal/permeability-increasing protein (BPI) is an endogenous antibiotic protein with activity against gram-negative bacteria. In the present study, we examined the expression of BPI in postnatal mouse testes and epididymides as well as the subcellular localization within epididymal spermatozoa. Our results showed that, BPI mRNA was expressed in testis and epididymis independently. Throughout the epididymis, the BPI protein level gradually decreased in the epididymal epithelium in a spatial manner, specialized within the cytoplasm of clear cells in the cauda part. We detected BPI proteins in intact acrosome, implying its testicular origin; on the other hand, after the acrosome reaction, BPI proteins were observed dispersed across the entire sperm head, especially enriched at the equatorial segment. Our findings suggested a dual origin of the BPI that generated both in the testis and epididymis, and associated with mouse spermatozoa. BPI protein might be involved in the dynamics modification of the sperm plasma membrane and also the fertilization process.