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.

Arachidic Acid in Extender Improves Post-thaw Parameters of Cryopreserved Nili-Ravi Buffalo Bull Semen

Abstract: Cryopreservation process reduces lipids and phospholipids from buffalo bull spermatozoa. It was therefore hypothesized that supplementation of fatty acid to extender may improve the post-thaw quality of buffalo semen. The objective was to evaluate the effect of arachidic acid supplementation in extender on post-thaw quality of buffalo bull (Bubalus bubalis) spermatozoa. Semen was collected from three adult Nili-Ravi buffalo bulls of similar age group with artificial vagina (42°C) for 3 weeks (replicate). Qualified semen ejaculates (n = 18) were split into four aliquots and diluted in tris-citric acid extender containing 0.0 (control), 5.0, 10.0 and 20.0 ng/ml at 37°C having approximately 50 × 10(6) spermatozoa/ml. Diluted semen was cooled to 4°C in 2 h and equilibrated for 4 h at 4°C. Cooled semen was filled in 0.5-ml straws at 4°C, kept on liquid nitrogen vapours for 10 min and plunged in liquid nitrogen for storage. Thawing of frozen semen was performed after 24 h at 37°C for 30 s. Sperm progressive motility (%) was improved in a dose-dependent manner by supplementing arachidic acid at 5.0, 10.0 and 20.0 ng/ml compared with control. Structural and functional integrity of sperm plasma membrane (%), number of acrosome-intact live sperm (%) and sperm chromatin integrity (%) were better (p 0.05) from those at 5.0 ng/ml. Further improvement in structural and functional integrity of sperm plasma membrane, number of acrosome-intact live sperm and chromatin integrity was observed at 20.0 ng/ml of arachidic acid in extender. In conclusion, arachidic acid supplementation in extender improved the post-thaw quality parameters of cryopreserved Nili-Ravi buffalo bull spermatozoa. Among the arachidic acid concentrations studied, maximum improvement in post-thaw semen quality parameters was observed at 20.0 ng/ml.

Utility of oxidative stress test in the male infertility clinic

Abstract: The controlled generation of very low amounts of reactive oxygen species (ROS) appears to regulate normal sperm functions, while high levels of ROS endanger sperm viability and function. Oxidative stress (OS) develops as a consequence of excessive production of ROS and/or impaired antioxidant defense system. It is proposed that such OS precipitates a range of pathologies currently thought to afflict male reproductive function. ROS-mediated peroxidative damage to the sperm plasma membrane may account for defective sperm function observed in a high proportion of infertility patients. Excessive generation of ROS may also attack integrity of DNA in the sperm nucleus. DNA bases are susceptible to oxidative stress, and peroxidation of these structures can cause base modification, DNA strand breaks and chromatin cross-linking. DNA damage induced by excessive ROS may accelerate the process of germ cell apoptosis, leading to decline in sperm counts associated with male infertility, and may explain the apparent deterioration of semen quality observed during the past four to five decades. For almost a decade, our research team in the Cleveland Clinic Foundation has identified the critical role of OS in male infertility. The main objective of our research was to transfer this important knowledge from the research bench to clinical practice. We designed studies with the aims of: 1. understanding the exact mechanisms by which OS develops in semen, which we thought will help setup strategies to overcome the problem, 2. establishing assays for accurate assessment of OS status and running the quality control studies for this purpose, 3. testing the correlation between OS and sperm nuclear DNA damage, and 4. identifying the clinical significance of seminal OS assessment in male infertility practice.

Effect of astaxanthin on the quality of boar sperm stored at 17°C, incubated at 37°C or under in vitro conditions.

Abstract: The aim of the study was to investigate the effect of the antioxidant astaxanthin on boar semen. Twenty ejaculates from 10 boars (two ejaculates/boar) were extended and split in three groups: semen control (SC), solvent control (C; semen with dimethyl sulfoxide, the diluent of astaxanthin) and semen with astaxanthin (A) in concentration 0.5 μmol/L. Sperm quality parameters (motility and kinetics, morphology, viability, functional integrity of sperm plasma membrane by Hypo-Osmotic Swelling Test [HOST] and DNA integrity) were assessed at 0, 24 and 48 hr of storage at 17°C (experiment I), before (0 hr) and after (1 hr) of sperm thermal resistance assay at 37°C (experiment II) and finally before (0 hr) and after (1 hr) sperm in vitro incubation (38.5°C, 5% CO2 , maximum humidity [experiment III]). In experiment I, group A performed overall better than group SC and as a tendency better than group C regarding viability. Total motility, rapid spermatozoa and HOST remained constant across time in group A, whereas they decreased in the remaining groups. In experiment II, regarding motility and viability, group A displayed better results across time than the other two groups. In experiment III, viability and total motility decreased in groups SC and C, while in group A, these parameters were not significantly different between the examination time points. In conclusion, astaxanthin has a beneficial and protective effect on boar semen quality under the investigated conditions.

Protein dynamics in sperm membranes: implications for sperm function during gamete interaction.

Abstract: A number of mammalian sperm plasma membrane antigens have been implicated as playing a functional role in sperm-egg interaction, by virtue of the fact that antibodies against these antigens interfere with fertilization. Two such muse sperm plasma membrane antigens are M42, a 200/220 kD glycoprotein doublet, and M5, a 150–160 kD glycoprotein. We show that both of these antigens are concentrated on the posterior region of caudal epididymal and capacitated mouse sperm heads and are relatively diffusible, as determined by fluorescence recovery after photobleaching measurements (D = 3–8 × 10–9 cm2/s with ∼ 23% diffusing). Crosslinking of these antigens with bivalent antibodies causes them to redistribute into the anterior region (acrosomal crescent) of the sperm head. In contrast, we describe a third antigen, P220, which is also localized to the posterior region of the sperm head on caudal epididymal sperm but which exhibits very little diffusion and does not redistribute upon crosslinking. Bivalent anti-M42 blocks the ZP3-induced acrosome reaction. We have found that monovalent Fab fragments of anti-M42 do not block the ZP3-induced acrosome reaction, but that inhibition is restored by addition of a second antibody which crosslinks the Fabs. Thus, crosslinking is required for both inhibition of the acrosome reaction and redistribution. This suggests that redistribution of antigen away from the posterior region of the head may be part of the mechanism of inhibition of the ZP3-induced acrosome reaction. © 1992 Wiley-Liss, Inc.

Effects of cryopreservation on progesterone-induced ion fluxes and acrosome reaction in human spermatozoa

Abstract: The present study evaluated the effects of cryopreservation on progesterone-induced variations of calcium ion concentration [Ca 2+ ] i , plasma membrane potential and acrosome reaction in human spermatozoa. Spermatozoa from 10 fertile donors were divided in two equivalent aliquots, one used as control (fresh spermatozoa) and the other used after freezing-thawing. Measurement of spermatozoa [Ca 2+ ] i before and after freezing-thawing showed a significant reduction of basal [Ca 2+ ] i in thawed spermatozoa (P < 0.01). Progesterone induced a rise of [Ca 2+ ] i both in fresh and thawed spermatozoa with a significant reduction after freezing-thawing (P < 0.01). The monitoring of sperm plasma membrane potential demonstrated that progesterone induced plasma membrane depolarization in fresh spermatozoa that was absent in thawed spermatozoa. The inhibitory effects of freezing-thawing on progesterone induced [Ca 2+ ] i and plasma membrane potential variations in human spermatozoa were closely related to the inhibition of the acrosome reaction. In conclusion the present study demonstrates that freezing-thawing procedures reduce the responsiveness of human spermatozoa to progesterone in terms of [Ca 2+ ] i rise and completely inhibit its effects on plasma membrane potential variations, thus supporting the hypothesis that freezing-thawing procedures may differently modify the plasma membrane receptors for progesterone in human spermatozoa which are known to express at least two receptors for this steroid in their plasma membrane.