Home About us Contact
|
Home About us Contact | ||
|
|
||
Sperm Membrane (sperm + membrane)
Selected AbstractsOC1 Effects of Cryopreservation on the Expression of Glut-3, Glut-5 and As-A Proteins in Iberian Boar Sperm MembranesREPRODUCTION IN DOMESTIC ANIMALS, Issue 2006S Sancho In order to determine the injure produced in boar spermatozoa through cryopreservation process, we analyzed the expression of the hexose transporters Glut-3 and Glut-5 and the zona pellucida binding protein As-A (P68) in three different steps of the freezing-thawed protocol: at 17°C (fresh BTS-diluted semen, 1 : 2 v/v, step 1), at 5°C (after glycerol addition; step 2), and post-thawing (step 3). All sperm analyses were carried out with immunogold techniques under electronic microscopy. For this study eight healthy post-pubertal Iberian boars were submitted to a collection of twice per week through 3 months, evaluating two ejaculates from each boar. Glut-3 maintains the expression in the acrosome region post-thawing but not along the tail where is reduced. The expression of Glut-5 and As-A is majority located at the post-acrosome region of the spermatozoa at step 1, but in step 2 and step 3 this expression is relocated to sperm tail area. In conclusion, while cryopreservation affects the localization and the expression of Glut-3 and Glut-5, its fertilizing capacity is not significantly reduced. The stabilization of boar semen at 5°C was found to be the most crucial step for sperm survival. [source] Gadolinium, a mechano-sensitive channel blocker, inhibits osmosis-initiated motility of sea- and freshwater fish sperm, but does not affect human or ascidian sperm motilityCYTOSKELETON, Issue 4 2003Zoltán Krasznai Abstract Exposure to hypo-osmotic or hyperosmotic environment triggers the initiation of fish sperm motility. In this article, we report that calcium and potassium channel blockers do not influence motility of puffer fish sperm but calmodulin antagonists reversibly decrease it, suggesting that calmodulin,Ca2+ interactions are prerequisite for the initiation of sperm motility in this species. Gadolinium (a stretch activated ion channel blocker) decreased the motility of puffer fish sperm from 92 ± 3% to 6 ± 3% and that of carp sperm from 91 ± 7% to 3.5 ± 4.3% in a dose-dependent manner (10,40 ,M). The effect of gadolinium was reversible, suggesting that stretch activated ion channels participate in the initiation of sperm motility of the two species. Gadolinium inhibits changes in the isoelectric point of certain proteins of puffer fish sperm, which occur when sperm motility is initiated in a hypertonic solution. Anisotropy measurements showed that hypo-osmotic treatment, which initiates carp sperm motility, increased membrane fluidity. When hypo-osmotic treatment was given in the presence of gadolinium, the sperm membrane remained as rigid as in quiescent cells, while motility was blocked. By contrast, gadolinium did not influence the motility parameters of Ciona or human sperm. Based on these lines of evidence, we suggest that conformational changes of mechanosensitive membrane proteins are involved in osmolality-dependent but not osmolality-independent sperm. Cell Motil. Cytoskeleton 55:232,243, 2003. © 2003 Wiley-Liss, Inc. [source] Role of sperm ,v,3 integrin in mouse fertilizationDEVELOPMENTAL DYNAMICS, Issue 3 2010Céline Chalas Boissonnas Abstract Oocyte integrins have been described as essential for fertilization. But this concept has been challenged by deletion experiments. Recently, we have shown that sperm integrin ,6,1 plays a determinant role in mouse gamete interaction. In this study, we demonstrate the presence of ,v,3 integrin by Western blot and immunofluorescence on the sperm membrane. Oocytes and/or sperm preincubations with anti-,v or anti-,3 antibodies were performed before in vitro fertilization on cumulus-intact and zona-free egg assays. We observed inhibitory effects on the fusion process mostly by means of sperm function. An antibody directed against vitronectin inhibited gametes fusion, whereas the presence of exogenous vitronectin increased its efficiency. We suggest that vitronectin (on multimeric forms) can play a first nonspecific link corresponding to loosely bound spermatozoa to oocyte and that this link could be mediated by means of oocyte proteoglycans or integrins, and sperm ,v,3 integrin. Developmental Dynamics 239:773,783, 2010. © 2010 Wiley-Liss, Inc. [source] The Use of HOS Test to Evaluate Membrane Functionality of Boar Sperm Capacitated in vitroREPRODUCTION IN DOMESTIC ANIMALS, Issue 6 2002D Lechniak Contents The functional and structural integrity of sperm membrane are crucial for the viability of spermatozoa. The commonly used staining test (eosin + nigrosin) for assessing sperm membrane measures only its structural integrity. The hypoosmotic swelling test (HOS) originally developed for human sperm (Jeyendran et al. 1984) has been also applied to several species of domestic animals (bull, pig, horse, dog). The test enables to evaluate the functional status of the sperm membrane. The principle of HOS is based on water transport across the sperm tail membrane under hypoosmotic conditions. It has previously been used to assess the semen quality (Revell and Mrode 1994), to analyse fertilizing capacity (Rota et al. 2000; Perez-Llano et al. 2001) and also to detect viable, immotile cells for ICSI (Intra-cytoplasmic sperm injection) in human (Zeyneloglu et al. 2000). There are two procedures commonly used for sperm capacitation in the pig-sperm washing and incubation before insemination (Nagai 1994). Capacitation involves several changes like removing molecules coating the sperm head membrane, changes in membrane fluidity and intracellular ion concentration (Green and Watson 2001). Thus the membrane integrity as well as functionality may be affected as shown by Harrison (1996). The aim of the present study was to analyse changes in sperm membrane integrity after in vitro capacitation by use of the HOS test. [source] REVIEW ARTICLE: Clinical Relevance of Oxidative Stress in Male Factor Infertility: An UpdateAMERICAN JOURNAL OF REPRODUCTIVE IMMUNOLOGY, Issue 1 2008Ashok Agarwal Male factor has been considered a major contributory factor to infertility. Along with the conventional causes for male infertility such as varicocele, cryptorchidism, infections, obstructive lesions, cystic fibrosis, trauma, and tumors, a new, yet important cause has been identified: oxidative stress. Oxidative stress (OS) is a result of the imbalance between reactive oxygen species (ROS) and antioxidants in the body, which can lead to sperm damage, deformity and eventually male infertility. This involves peroxidative damage to sperm membrane and DNA fragmentation at both nuclear and mitochondrial levels. OS has been implicated as the major etiological factor leading to sperm DNA damage. OS-induced DNA damage can lead to abnormalities in the offspring including childhood cancer and achondroplasia. In this article, we discuss the need of ROS in normal sperm physiology, the mechanism of production of ROS and its pathophysiology in relation to male reproductive system. The benefits of incorporating antioxidants in clinical and experimental settings have been enumerated. We also highlight the emerging concept of utilizing OS as a method of contraception and the potential problems associated with it. [source] Decreased polyunsaturated and increased saturated fatty acid concentration in spermatozoa from asthenozoospermic males as compared with normozoospermic malesANDROLOGIA, Issue 5 2006H. Tavilani Summary The lipid composition of the sperm membrane has been shown to exert a significant effect upon the functional quality of spermatozoa. We have studied fatty acid composition of the phospholipids in spermatozoa in asthenozoospermic and normozoospermic men and determined the ratio of polyunsaturated fatty acids (PUFAs) to saturated fatty acids of spermatozoa of these two groups. Fatty acid concentration of spermatozoa was determined in 15 asthenozoospermic and eight normozoospermic semen samples by thin layer chromatography and gas chromatography. The most abundant polyunsaturated and saturated fatty acids in normozoospermic samples were docosahexaenoic acid (DHA 22 : 6 ,3, 98.5 ± 4.5 nmol per 108 spermatozoa, mean ± SE) and palmitic acid (103 ± 17 nmol per 108 spermatozoa) respectively. The mean ± SE values of DHA and palmitic acid in asthenozoospermic samples were 53.9 ± 11.6 and 145 ± 14.7 nmol per 108 spermatozoa respectively. Compared with normozoospermic samples, asthenozoospermic samples showed lower levels of PUFA and higher amount of saturated fatty acids. The mean ± SE ratios of sperm PUFA/saturated fatty acids in asthenozoospermic and normozoospermic samples were 0.66 ± 0.06 and 1.45 ± 0.16 (P < 0.001) respectively. This study demonstrates that spermatozoa of asthenozoospermic men have lower levels of PUFA compared with saturated fatty acids. This may be contributory to the poor motility noted in samples from these men. [source] Lipid peroxide formation in relation to membrane stability of fresh and frozen thawed stallion spermatozoaMOLECULAR REPRODUCTION & DEVELOPMENT, Issue 2 2005D.M. Neild Abstract In this study we used a new method to detect reactive oxygen species (ROS) induced damage at the level of the sperm plasma membrane in fresh and frozen-thawed stallion sperm. Lipid peroxidation (LPO) in sperm cells was assessed by a fluorescent assay involving the labeling of stallion sperm with the LPO reporter probe C11-BODIPY581/591. The peroxidation dependent spectral emission shift of this membrane probe could be localized using inverted spectral confocal microscopy and quantified on living and deteriorated sperm cells using flow cytometry. Mass spectrometric analysis of the main endogenous lipid class, phosphatidylcholine (PC), was carried out to determine the formation of hydroxy- and hydroperoxyphosphatidylcholine in fresh sperm cells. Peroxidation as reported by the fluorescent probe corresponded with the presence of hydroxy- and hydroperoxyphosphatidylcholine in the sperm membranes, which are early stage products of LPO. This allowed us to correlate endogenous LPO with localization of this process in the living sperm cells. In absence of peroxidation inducers, only relatively little peroxidation was noted in fresh sperm cells whereas some mid-piece specific probe oxidation was noted for frozen-thawed sperm cells. After induction of peroxidation in fresh and frozen-thawed sperm cells with the 0.1 mM of lipid soluble ROS tert -butylhydrogen peroxide (t -BUT) intense probe oxidation was produced in the mid-piece, whereas the probe remained intact in the sperm head, demonstrating antioxidant activity in the head of fresh sperm cells. At higher levels of t -BUT, probe peroxidation was also noted for the sperm head followed by a loss of membranes there. Frozen-thawed sperm were more vulnerable to t -BUT than fresh sperm. The potential importance of the new assays for sperm assessments is discussed. © 2005 Wiley-Liss, Inc. [source] Roles of antioxidants on prolonged storage of avian spermatozoa in vivo and in vitroMOLECULAR REPRODUCTION & DEVELOPMENT, Issue 3 2003Christelle Bréque Abstract This review focuses on natural and assisted prevention against lipid peroxidation in avian spermatozoa. The presence of high levels of n-6 polyunsaturated fatty acids (PUFAs) in the plasma membrane creates favorable conditions for the formation of peroxidative products, a major cause of membrane damage which may ultimately impair male fertility. However, a complex antioxidant system involving vitamin C, vitamin E and GSH is naturally present in avian semen. Coupled with a battery of enzymatic defenses (e.g., SOD, GSH-Px either Se- or non-Se-dependent), this system acts to prevent or restrict the formation and propagation of peroxides. The presence of specialized sites dedicated to prolonged sperm storage in avian females raises the question of durable protection of sperm membranes against peroxidation. Preliminary observations have revealed the presence of a specific antioxidant system at these sites in which vitamin C could exert a major role. From a practical standpoint, the extensive use of artificial insemination in poultry, along with the emergence in some species of workable techniques to cryopreserve spermatozoa, demand better control of peroxidation occurring in the plasma membrane of spermatozoa before or during storage. Dietary supplementation with vitamin E is effective in limiting lipid peroxidation of sperm plasma membranes, both in chickens and turkeys. In addition, organic Se with or without vitamin E stimulates Se-GSH-Px activity in seminal plasma. Preliminary observations in female chickens have also revealed the effectiveness of dietary supplementation with vitamin E, organic selenium or both to sustain fertility in aging flocks. Mol. Reprod. Dev. 66: 314,323, 2003. © 2003 Wiley-Liss, Inc. [source] | |||||||||||||