Lipid changes of goat sperm plasma membrane during epididymal maturation
TL;DR: The altered lipid profile of the mature sperm membrane leads to changes in its fluidity that play an important role in determining the structure and functions of the biomembrane.
About: This article is published in Biochimica et Biophysica Acta.The article was published on 1991-01-30. It has received 76 citations till now. The article focuses on the topics: Sperm plasma membrane & Membrane lipids.
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TL;DR: Observations suggest that CLC treatment could be used to improve cryoprotection during the freezing and thawing of goat sperm.
Abstract: The success of semen cryopreservation depends on sperm membrane integrity and function after thawing. Cholesterol-loaded cyclodextrin (CLC) is used for in vitro incorporation of cholesterol to protect cells against cold temperatures. We hypothesized that CLC treatment also enhances sperm cholesterol content to increase tolerance to osmotic shock and cryoresistance, thereby improving fertility. We confirmed the fact that treatment of goat semen with 3 mg/ml CLC increases sperm cholesterol content using both the Liebermann-Burchard approach and filipin III labeling of membrane cholesterol. Sperm were then treated with or without CLC and cryopreserved. After thawing, sperm cholesterol dramatically fell, even in the presence of CLC, which explains the mechanism of cryocapacitation. CLC treatment, however, maintained a normal prefreeze cholesterol level in sperm after cryopreservation. Furthermore, fresh sperm treated with CLC and subjected to either cold shock or incubated in hypo-, iso-, and hyperosmotic media, designed to mimic stresses associated with freezing/thawing, displayed increased temperature and osmotic tolerance. CLC treatment also improved sperm viability, motility, and acrosome integrity after thawing. Furthermore, CLC treatment did not affect the sperm's ability to undergo in vitro capacitation according to chlortetracycline fluorescence and protein tyrosine phosphorylation. A pilot field trial demonstrated that artificial insemination with sperm that underwent increased cholesterol levels following CLC treatment yielded higher fertility ( ITALIC! P< 0.1) and proliferation ( ITALIC! P< 0.05) rates in vivo than untreated semen from the same ejaculate samples. These observations suggest that CLC treatment could be used to improve cryoprotection during the freezing and thawing of goat sperm.
27 citations
Cites background from "Lipid changes of goat sperm plasma ..."
...35 [12, 13], which may explain species differences in resistance to cryopreservationinduced damages....
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TL;DR: The results show that SVS2 keeps sterols on the sperm plasma membrane and plays a key role in unlocking sperm capacitation in vivo.
Abstract: Seminal vesicle secretion 2 (SVS2) is a protein secreted by the mouse seminal vesicle. We previously demonstrated that SVS2 regulates fertilization in mice; SVS2 is attached to a ganglioside GM1 on the plasma membrane of the sperm head and inhibits sperm capacitation in in vitro fertilization as a decapacitation factor. Furthermore, male mice lacking SVS2 display prominently reduced fertility in vivo, which indicates that SVS2 protects spermatozoa from some spermicidal attack in the uterus. In this study, we tried to investigate the mechanisms by which SVS2 controls in vivo sperm capacitation. SVS2-deficient males that mated with wild-type partners resulted in decreased cholesterol levels on ejaculated sperm in the uterine cavity. SVS2 prevented cholesterol efflux from the sperm plasma membrane and incorporated liberated cholesterol in the sperm plasma membrane, thereby reversibly preventing the induction of sperm capacitation by bovine serum albumin and methyl-beta-cyclodextrin in vitro. SVS2 enters the uterus and the uterotubal junction, arresting sperm capacitation in this area. Therefore, our results show that SVS2 keeps sterols on the sperm plasma membrane and plays a key role in unlocking sperm capacitation in vivo.
27 citations
Cites background from "Lipid changes of goat sperm plasma ..."
...The cholesterol concentration on the sperm plasma membrane increases during epididymal transit [44, 45]....
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TL;DR: The data demonstrate asymmetry of phospholipids and their fatty acids in the sperm inner and outer plasma membranes and this lipid asymmetry is greatly altered during epididymal maturity of the male gametes.
25 citations
TL;DR: Observations predict HSL to be an important player in controlling the balance of substrate utilization and storage.
Abstract: The mobilization of fatty acid from triglycerides and cholesterol esters provides the primary source of energy in mammals. Hormone-sensitive lipase (HSL) is a multifunctional tissue lipase that plays a critical role in this process. The enzyme has broad specificity, catalyzing the hydrolysis of tri-, di-, and monoacylglycerols, as well as cholesterol esters. HSL has been studied most extensively in adipose tissue, where it is thought to catalyze the major rate-limiting step in lipolysis. The lipase is acutely activated by cAMP-dependent phosphorylation, which also leads to its redistribution from the cytoplasm to the lipid droplet (1, 2) (Fig. 1). Regulation of adipocyte HSL is the primary means by which lipolytic agents, such as catecholamines, stimulate the release of free fatty acids (FFAs) and thus control circulating levels. Plasma FFAs profoundly influence carbohydrate and lipid utilization, storage, and synthesis, both in liver and muscle. Moreover, fatty acids produced in fat cells can uncouple ATP synthesis, resulting in adaptive thermogenesis (3). Products of fatty acid metabolism are also thought to bind directly to nuclear receptors, thus regulating transcription of genes involved in lipid synthesis and breakdown (4). These observations predict HSL to be an important player in controlling the balance of substrate utilization and storage.
23 citations
TL;DR: The overall Japanese recommendation is that the ICH S6 guideline should be updated to address new types of biopharmaceuticals such as bioconjugates, use of homologous proteins and transgenic animals, reproductive/developmental toxicity studies in non-human primates, in vitro cardiac ion channel assay and alternative approaches for carcinogenicity assessment.
Abstract: Safety assessment of biopharmaceuticals in preclinical studies is guided by the ICH S6 guideline issued in 1997. Along with enormous experiences and knowledge on safety assessment of some classes of biopharmaceuticals over the last decade, the necessity and feasibility of updating the guideline has been discussed. According to a recommendation by safety experts at the ICH meeting in Chicago in 2006, regional discussions of ICH S6 were held in the USA, EU and Japan. The meeting to clarify the values, challenges and recommendations for ICH S6 from Japanese perspective was held as a part of the first Drug Evaluation Forum in Tokyo on August 10, 2007. Of utmost importance, the "case-by-case" approach must be preserved as the basic principle of the ICH S6 guideline. It is our opinion that oligonucleotides, siRNA, aptamers and related molecules should be excluded from ICH S6 and may be more appropriate for separate guidance. However, based on experiences and accumulated knowledge, there are a number of issues that can be updated including new types of biopharmaceuticals such as bioconjugates, use of homologous proteins and transgenic animals, reproductive/developmental toxicity studies in non-human primates, in vitro cardiac ion channel assay and alternative approaches for carcinogenicity assessment. Preliminary recommendations for some of these topics were outlined at the meeting. The overall Japanese recommendation is that the ICH S6 guideline should be updated to address these topics.
22 citations
Cites background from "Lipid changes of goat sperm plasma ..."
...Lipid changes occur during the epididymal transit of spermatozoa as they mature, indicating that alterations in membrane fluidity by lipid remodeling plays an important role in determining the structure and functions of the sperm membrane (Rana et al., 1991; Aveldano et al., 1992)....
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References
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Journal Article•
TL;DR: Procedures are described for measuring protein in solution or after precipitation with acids or other agents, and for the determination of as little as 0.2 gamma of protein.
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TL;DR: In this paper, the authors described a simplified version of the method and reported the results of a study of its application to different tissues, including the efficiency of the washing procedure in terms of the removal from tissue lipides of some non-lipide substances of special biochemical interest.
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TL;DR: Separation of polar lipids by two-dimensional thin layer chromatography providing resolution of all the lipid classes commonly encountered in animal cells and a sensitive, rapid, reproducible procedure for determination of phospholipids by phosphorus analysis of spots are described.
Abstract: Separation of polar lipids by two-dimensional thin layer chromatography providing resolution of all the lipid classes commonly encountered in animal cells and a sensitive, rapid, reproducible procedure for determination of phospholipids by phosphorus analysis of spots are described. Values obtained for brain and mitochondrial inner membrane phospholipids are presented.
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