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.

Cryopreservation of dog semen in a Tris extender with two different 1% soybean preparations compared with a Tris egg yolk extender.

Abstract: Egg yolk is widely used as a cryoprotectant in dog semen extenders, but there is a risk of contamination with animal pathogens. In addition, egg yolk may vary in composition, making it difficult to standardize the extender. Lecithin is an animal protein-free alternative to egg yolk for semen cryopreservation. Recently, it was shown that 1% of soybean lecithin type II-S was better than 2% for freezing canine semen. The aim of the study was to compare two different types of soybean lecithin, with egg yolk as a control. Ejaculates from eight dogs were divided into three equal parts and diluted with a Tris-based extender, containing either 20% egg yolk, 1% soybean lecithin Type II-S or 1% soybean lecithin Type IV-S. The samples were then frozen. Sperm motility was evaluated by computer-assisted sperm analysis (CASA), acrosome integrity (FITC-PNA/PI) and sperm membrane integrity (SYBR-14/PI) post-thaw, as well as after 2 and 4 hr incubation at 37 degrees C. Post-thaw sperm chromatin structure assay and plasma membrane integrity were evaluated by flow cytometry. Total motility, sperm plasma membrane integrity and acrosome integrity were significantly better in the egg yolk extender than in the two soybean lecithin-based extenders. Individual motility post-thaw differed more than in the fresh samples, illustrating individual differences in tolerance to the cryostress. The DNA Fragmentation Index (% DFI) was significantly lower in the Tris egg yolk (TEY) extender compared to any of the soybean-based extenders. The number of high green stained spermatozoa were significantly higher in Type IV-S compared to the control TEY extender. In conclusion, egg yolk was superior to the two lecithin-based extenders to cryopreserve canine semen.

Rabbit epididymal secretory proteins. II. Immunolocalization and sperm association of REP38

Abstract: Polyclonal antibody was used to partially characterize REP38, a major rabbit epididymal secretory protein. Western blot analyses and immunohistochemistry indicated that REP38 is only expressed in regions 5 and 6 of the epididymis (corpus epididy-midis) and is localized in the supranuclear region and microvilli of the principal cells in these regions. It was not expressed in other tissues of the body. In region 8 (cauda epididymidis), REP38 was detected in the luminal border and cytoplasm of scattered principal cells, indicating that it may be reabsorbed in this region. This protein accumulated on the sperm plasma membrane downstream of region 5 and was localized predominantly over the acrosomal and postacrosomal regions of the head and the middle piece. Although tightly bound to epididymal sperm, REP38 migrated to the equatorial segment under conditions in vivo that would promote capacitation. When tested in vitro, anti-REP38 IgG reduced the percentage of ova fertilized in a concentration-dependent manner, apparently by blocking sperm-egg fusion.

208 effect of refrigeration and cryopreservation on the quality of lion epididymal spermatozoa

Abstract: Epididymal spermatozoa from harvested wild animals is potentially useful for conservation purposes, as it can be used for subsequent artificial insemination or stored in Biological Resource Banks for future use. The potential of sperm banking is of particular interest for use in lion (Panthera leo) populations maintained in small National Parks, as translocation of males to effect gene-flow is often problematic, resulting in the translocated lion being killed by resident pride males. We measured the change in sperm quality over time during cool storage (at 4°C) and after thawing of samples cryopreserved at −196°C. Also, we present a correlation between sperm plasma membrane integrity and mitochondrial activity as measured by fluorescent analysis. The testes from a pride lion were removed and transported to the laboratory (at 4°C) within 6 h. The epididymides were removed and both cauda epididymides were flushed with 1 mL of Tris-citrate egg yolk extender (Fraction A, Biladyl, Minitub, Germany). The sample containing 2930 × 106 cells mL−1 was washed (20 mM HEPES, 355 mM sucrose, 10 mM glucose, 2.5 mM KOH;; 400 mOsm/kg, pH 7; Sigma, South Africa) and after centrifugation (5 min. at 600g), the pellet was resuspended in 0.5 mL of washing solution (with 197 mM NaCl instead of sucrose). One aliquot of spermatozoa was kept at 4°C and evaluated at 24 h intervals for 7 days. A second aliquot of the sperm sample was extended in Tris-citrate egg yolk extender with glycerol (Fraction B, Biladyl), frozen in liquid nitrogen (LN) vapor and stored in LN. The frozen sample was later thawed and evaluated as for the cooled samples. Percentages of motile (MS) and progressive (PS) spermatozoa were assessed using a phase contrast microscope (×200; stage at 37°C). Sperm plasma membrane damage was assessed by determining the percentage of cells exhibiting red fluoresence after staining with propidium iodide (PI, 50 ng/mL; 10 min RT). Spermatozoa that did not stain red in PI were classified as plasma membrane intact (PMI). Resilience to hypo-osmotic shock and plasma membrane integrity were evaluated by incubating a portion of the sample in a 100 mOsm/kg solution (10 nM glucose, 20 nM HEPES, 30 nM NaCl) containing PI for 15 min at room temperature. The percentage of sperm cells with active mitochondria (MIT) was determined by counting spermatozoa showing orange fluoresence over the mid-piece after staining with JC-1(7.5 uM Sigma) for 30 min at 37°C. At collection, MS was 15% and did not show a significant decrease during the 7-day storage period. Initially, PS was 10% and dropped to 5% after 7 days, with values fluctuating during the storage period. Both PMI and HOSPMI were 80% on Day 1, gradually decreasing to 75% on Day 7 of storage. PMI and MIT showed a highly significant correlation (r = 0.88; P = 0.003; n = 8). In frozen-thawed sperm samples, MS fell from a pre-freeze value of 15% to 5% after thawing. Similarly, PS fell from 10% in pre-freeze to 3% in frozen-thawed samples. Likewise, PMI, HOSPMI and MIT values were 80% and 45%, 87% and 45% and 89% and 49%, respectively. Our study showed that lion sperm PMI and MIT remained high after 7 days at 4°C. MS and PS, although low, did not vary during this same period. PI and JC-1 showed a significant correlation, suggesting that both might be affected by the same deleterious factors. Although PMI, HOSPMI and MIT values decreased approximately 40% after freezing, we feel that such sperm samples could be used for in vitro embryo production, if not by IVF, by ICSI. Of course, additional studies are needed to validate our suggestion.