Detecting subtle changes in sperm membranes in veterinary andrology

Thanks to the increasing use of flow cytometry in research in veterinary spermatology, many new membrane integrity assays have been developed over the past decade. These assays are important because of their superior ability to forecast fertility when compared with other tests, such as sperm motility. This major component of the sperm quality assessment has generated new investigations with the aim of developing tests that can detect membrane damage in a very early state. Using phospholipid transposition tests, early changes in membrane permeability and fluidity can be assessed in a large number of spermatozoa using fluorescent probes in combination with flow cytometry.

Supramolecular organization of the sperm plasma membrane during maturation and capacitation

Aim： In the present study, a variety of high resolution microscopy techniques were used to visualize the organization and motion of lipids and proteins in the sperm＇s plasma membrane. We have addressed questions such as the presence of diffusion barriers, confinement of molecules to specific surface domains, polarized diffusion and the role of cholesterol in regulating lipid rafts and signal transduction during capacitation. Methods： Atomic force microscopy identified a novel region （EqSS） within the equatorial segment of bovine, porcine and ovine spermatozoa that was enriched in constitutively phosphorylated proteins. The EqSS was assembled during epididymal maturation. Fluorescence imaging techniques were then used to follow molecular diffusion on the sperm head. Results： Single lipid molecules were freely exchangeable throughout the plasma membrane and showed no evidence for confinement within domains. Large lipid aggregates, however, did not cross over the boundary between the post-acrosome and equatorial segment suggesting the presence of a molecular filter between these two domains. Conclusion： A small reduction in membrane cholesterol enlarges or increases lipid rafts concomitant with phosphorylation of intracellular proteins. Excessive removal of cholesterol, however, disorganizes rafts with a cessation of phosphorylation. These techniques are forcing a revision of long-held views on how lipids and proteins in sperm membranes are assembled into larger complexes that mediate recognition and fusion with the egg. （Asian JAndrol 2007 July; 9： 438-444）

Sperm membrane modulation by Sapindus mukorossi during sperm maturation

Aim: To observe the alterations in the biochemical and biophysical changes in the sperm membrane during sperm maturation in male rats treated with the water extract of the fruit pericarp of S. mukorossi. Methods: Adult male Sprague-Dawley rats were gavaged the aqueous extract of the fruit pericarp of S. mukorossi at a dose of 50 mg/kg/d for 45 days. On day 46, the sperm parameters were observed in different sections of the epididymis and the sperm superoxide dismutase and the lipid peroxidation was determined and compared with the controls. The testis and epididymis were routinely prepared for histological examination under the light microscope. Results: No significant differences in the sperm number and morphology were observed between the control and treated groups. However, a significant inhibition (P<0.05-0.01) of sperm motility in the caput, corpus and cauda regions of the epididymis was seen in the treated group. No significant histopathological changes were found in the testis and epididymis. The important finding was that in the treated animals, the spermatozoa showed an abnormal distribution of the superoxide dismutase activity, being minimum in the caput and maximum in the corpus, which was just opposite to that of the controls. Conclusion: The study provides a unique observation where the plant extract alters the sperm membrane physiology without change the testicular and epididymal morphology.

Whole-body heat exposure induces membrane changes in spermatozoa from the cauda epididymidis of laboratory mice

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℃-38℃ for 8 h per day for three consecutive days, while control mice （n = 7） were kept at 23℃-24℃. 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℃-38℃ induces membrane changes in the epididymal spermatozoa of mice, which may lead to apoptosis.

Influence of enterococci on human sperm membrane in vitro

Aim： To study the influence of enterococci on human sperm membrane in vitro. Methods： Ejaculated human sperm were artificially infected with β-hemolytic or non-β-hemolytic enterococci at the bacteria： sperm ratio of 50：1 at 37℃. Sperm membrane integrity was examined after incubation for 1, 3 and 5 h by hypoosmotic swelling （HOS） test and electron microscopy. Results： Sperm infected with β-hemolytic enterococci had lower HOS scores compared with non-β-hemolytic strains or uninfected control （P 〈 0.01）. The HOS test scores of sperm infected with β-hemolytic enterococci increased in the presence of phosphatidylcholine, an inhibitor of hemolysin. Non-β-hemolytic strains showed no significant difference in swelling rate, compared with the control group （P 〉 0.05）. It was shown by electron microscopy that β-hemolytic enterococci caused significant rupture of human sperm membrane. Conclusion： β-hemolytic enterococci caused human sperm membrane injury, and might be mediated by the hemolysin of enterococci.

Inhibition of mouse acrosome reaction and sperm-zona pellucida binding by anti-human sperm membrane protein 1 antibody

Aim： To investigate the possible functions of human sperm membrane protein （hSMP-1） in the process of fertilization. Methods： A 576-bp cDNA fragment of HSD-1 gene coding for the extracellular domain of hSMP-1 was cloned and expressed. The localization of this protein on human and mouse sperm was determined by indirect immunofluorescent staining by using anti-recombinant hSMP-1 （anti-rhSMP-1） antibodies. Sperm acrosome reaction and spermzona pellucida （ZP） binding assay were carried out in 10-week-old BALB/c mice. Results： Recombinant hSMP-1 was successfully cloned and expressed. The expression of the native protein was limited on the acrosome of human and mouse sperm. Treatment of anti-rhSMP-1 antibodies significantly decreased the average number of sperms bound to each egg. Meanwhile, the percentage of acrosome reaction was decreased in comparison to pre-immune control after treatment with anti-rhSMP-1 （P 〈 0.05）. Conclusion： The results suggest that anti-rhSMP-1 antibody inhibited mouse acrosome reaction and sperm-ZP binding.

Analysis of Sperm Membrane Protein Relevant to Antisperm Antibody by Two-Dimensional Gel Electrophoresis and Western Blotting

Objective To identify the sperm membrane proteins that are associated with antisperm antibody Methods Using antisperm antibody positive serum through unidimensional polyacrylamide gel electrophoresis and 2-dimensional gel electrophoresis followed by Western blot analysis to determine the molecular weights (MW) and isoelectric points (pI) of sperm membrane proteins that are associated with antisperm antibody. Results Eight kinds of MW with more than ten sperm membrane proteins can be recognized by antisperm antibody positive serum, of which the MWs and pI were 23 kD, 31 kD, 32 kD, 34 kD, 41 kD, 51 kD, 60 kD, 78 kD and 5.3, 5.5,5.7, 5.0, 5.3, 5.8, 6.0, 5.5～6.2, 4.6,5.1,5.5～5.8 respectively. The identification ratios of the sperm membrane proteins on 78 kD (60.7%), 60 kD (71.4%), 51 kD (14.9%) and 23 kD (14.29%) were higher. Conclusion The sperm membrane proteins with MW of 78 kD, 60 kD, 51 kD and 23 kD were associated with antisperm antibody and immunological infertility. Two- dimensional gel electrophoresis and Western blotting can precisely identify the sperm membrane proteins that are associated with antisperm antibody.

A patch-clamp study on human sperm Cl^- channel reassembled into giant liposome

Aim: To record the single-channel currents and characterize the electrophysiological properties of the Cl^- channels inhuman sperm membrane. Methods: The membrane proteins extracted from the human sperm were reassembled intoliposome bilayer, and the liposomes were fused into giant liposomes with a diameter more than 10μm by dehydration-rehydration procedure. The giant liposomes were used to study the Cl^- channel activities by patch-clamp technique.Results: By patch clamping the giant liposome in an asymmetric NMDG (N-methyl-D-glucamine)-Cl (bath 100//pipette 200 mmol/L) solution system, three kinds of single-channel events with unit conductances of (74.1 ± 8.3) pS,(117.0±5.7) pS and (144.7±4.5) pS, respectively, were detected. Their activities were voltage-dependent and allwere blocked by SITS (4-acetamido-4'-isothiocyanato-stilbene-2', 2'-disulfonic acid) in a concentration-dependentmanner. By constructing the open and close dwell time distribution histograms and then fitting them with exponentialfunction, two time constants were obtained in both the open and the close states. The burst activity and conductancesubstate of the channels were observed. Conclusion; There exist three kinds of Cl^- channels with different conduc-tance in human sperm membrane at least. (Asian J Androl 2001 Sep; 3: 185 - 191)

Effects of Clindamycin on Sperm Function in Mice

[ Objective] To study the effects of clindamycin on germ cells of male mice. [Method] A total of 48 healthy adult male mice were randomly divided into group A, group B, group C and control group, 12 mice in each group. The mice in the group A, group B and group C were respectively administrated with clindamycin at doses of 15, 30 and 60 mg/kg.d via intraperitoneai injection, and those in the control group were trea- ted with normal saline. On Day 29 after administration, the mice were killed by dislocation, and the sperm motility rate, sperm deformity rate and the percentage of sperm having swollen tail membrane were determined, respectively. [ Result] The sperm motility rate and the percentage of sperm having swollen tail membrane of the group B and group C were lower than those of the control group; and the sperm deformity rate of the group B and group C was higher than that of the control group. The sperm motility rate, sperm deformity rate and percentage of sperm having swollen tail membrane had no significant difference between the group A and control group. [ Conclusion] The clindamycin at a dose equal to or more than that used for severe infection affects the normal function of sperm in mice.

Analysis of sperm membrane antigens relevant to antisperm antibody using Western blot

To identify the sperm membrane antigens associated with antisperm antibody. Methods: The antisperm antibody in serum was tested by ELISA. Antisperm antibody positive sera from 18 infertile men and 15 infertile women were used. The molecular weight (MW) of sperm membrane antigens associated with the antisperm antibody was analyzed with antisperm antibody positive serum using Western blot. Results: Eight kinds of MW of sperm membrane antigens were identified. The ratio of identification on the 78 KD(60.7 %), 60KD (71.4 %), 51 KD (14.9 %) and 23 KD (14.29 %) sperm antigen was higher than others. Conclusion: Sperm membrane antigens with MW of 78 KD, 60 KD, 51 KD and 23 KD were associated with antisperm antibody and immunological infertility. (Chin J Andro12002; 16: 345)

Expression of Human Sperm Mem brane Protein in theRecom binantSalm onella Typhim urium Vaccine

A 550 bp cDNA fragment of HSD I coding for an extracellular domain of human sperm membrane protein (hSMP 1) was ligated with an Adapter containing the universal stop codon, and the ligated fragment cDNA was then cloned into the MAS of pUC19. The desired plasmid with correct open reading frame was obtained, and was cut with EcoR I.The insert was purified and then cloned into the two asd + Salmonella expression vectors (the low copy number plasmid pYA292 and the high copy number plasmid pYA3137). The recombinant plasmid containing the insert with the correct orientation was selected by restriction enzyme digestion analysis. The recombinant plasmids were transferred into the non pathogenic Salmonella typhimurium χ4550, which was deletion of the Δcya, Δcrp and Δasd genes. Western blot analysis of the whole cell lysate of the two recombinants of S. typhimurium showed a predominant protein band at 21 KD, which reacted with the anti hSMP 1 antiserum. The result indicated that two recombinants of S. typhimurium containing the 550 bp cDNA of HSD I were constructed and the characteristics of their growth in vitro were determined. They may be used as new potential mucosal immunization antifertility.

The Expression of Sperm Membrane Peptide-Hepatitis B SurfaceAntigen Fusion Protein with Recombinant Vaccinia Virus

A synthetic oligonucleotide, HSD-2a, encoding a peptide segment of the extracel-lular domain of a human sperm membrane protein, YWK-II, was fused with hepatitisB surface antigen gene (HBs gene ). The fused gene was then cloned to pUC18plasmid. The fused gene was prepared from the recombinant pUC18 plasmid byBamH I and Eco R I digestion, and then cloned into the transfer vector pGJP- 5 underthe control of P;., promoter, designated as pGJP-HSD/HBs. CV-1 cells were co-transfected with vaccinia virus (Tian Tan strain) and pGJP-HSD/IIBs and homolo-gous re combination occurred between the vaccinia virus TK gene of the plasmid flank-ing the foreign gene and the same sequences within the virus genome. TK phen0tyPerecombinant virus, vv-HSD/HBs, were selected from trandected HuTK' cells byplaque purthcation technique. The eopressi0n of HSD-b in spent medium and cellu-lar protein of HuTK cells infected with vv-HSD/HBs was determined by ELISAand Western-blot analysis using anti-rwK-II antiserum. The present study indicatesthat the vv-HSD/HBs seems promising as an antdertility vaccine.

Effects of the crude extract of Polygala tenuifolia Willd on human sperm in vitro

The aim of the present study is to analyze sperm membrane changes and the spermicidal effect in treatment with the crude extract from Polygala tenuifo/ia Willd （PTW） in vitro. The root of PTW was extracted in distilled water. Normal human spermatozoa were used to assess the spermicidal activity （Sander-Cramer assay） of the extract from the PTW root. The hypo-osmotic swelling （HOS） test and the eosin Y （EY） staining were used to detect the integrity of sperm membrane and vitality. The sperm chromatin dispersion （SCD） test was performed to determine sperm DNA integrity. N-9 was used as a reference standard and semen added to physiological saline was used as the control. Semen samples were donated by 42 healthy fertile men. The crude extract from the root of PTW could immobilize and kill 100% spermatozoa within 20 s in vitro at the concentrations of 20.0 and 10.0 mg/ml; at the concentration of 5.0 mg/ml, spermatozoa were immobilized in （39.5±3.2） s. In the groups of the crude extract from the root of PTW and N-9 solution the rate of the normal HOS （tails swollen） and the white head （unstained） was 0%, and the rate of the abnormal HOS （tails unswollen） and red head （stained） was 100%. Sperm DNA fragmentation showed no change in exposure to the crude extract from the root of PTW and N-9 solution. The sperm revival test did not show any spermatozoa that recovered their motilities. The rapid spermicidal activity of the crude extract from the root of PTW in vitro may occur by the disruption of the sperm membrane integrity.