Mammalian sperm preservation: mechanism sperm protection by milk and development of novel extenders

哺乳动物精子保存：乳汁保护精子的机制和新型延长剂的开发

• 批准号: 138116-2009
• 负责人: Manjunath, Puttaswamy
• 金额: $ 2.7万
• 依托单位: Université de Montréal
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2012
• 资助国家: 加拿大
• 起止时间: 2012-01-01 至 2013-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=504194
• 关键词: Mammalian; sperm; preservation; mechanism; protection

The cryopreservation of bull semen represents one of the most important achievements in dairy farming after the introduction of artificial insemination. These two approaches have enabled the worldwide distribution and use of desired genetic lines at a reasonable cost. Canada represents <3% of the global economy but provides >20% of world bovine semen exports (~70 million dollars/annum). Egg yolk (EY) and skimmed milk are the most used protective agents to freeze mammalian sperm. EY and milk, being products of animal origin, represent a potential risk of contamination of semen and moreover, their composition is not uniform. Thus, there is an urgent need of developing novel media free of products from animal origin to conserve semen. However, it is difficult to find replacement component for EY or milk because the mechanisms involved in sperm protection by EY and milk against cooling, freezing and storage damages remains unclear. Over the past six years we provided evidences, which indicate that the sperm protection by EY involves an association of EY low-density lipoproteins (LDL) with seminal plasma proteins that are detrimental to sperm storage. These detrimental proteins originally discovered in bovine seminal plasma (hence BSP proteins) have the potential to extract lipids from the sperm membrane thereby adversely affecting the ability of sperm to be preserved. However, when these BSP proteins are associated with LDL, they lose their ability to extract lipid from the sperm membrane, which is the origin for sperm protection (novel concept). Interestingly, skimmed milk, which does not contain lipoproteins, also protects sperm during storage. Thus we hypothesize that the casein micelles and whey proteins, which are the major components of milk bind to BSP proteins and this interaction is the key for sperm protection. The current program is aimed at understanding of the mechanisms involved in sperm protection by egg yolk and milk, which would help us to develop novel extenders for commercial application that do not contain animal products.

公牛精液的冷冻保存是继人工授精之后奶牛养殖业最重要的成就之一。 这两种方法使得能够以合理的成本在世界范围内分配和使用所需的遗传品系。 加拿大占<3% of the global economy but provides >世界牛精液出口量的20%（每年约7000万美元）。 蛋黄（EY）和脱脂牛奶是冷冻哺乳动物精子最常用的保护剂。 EY和牛奶是动物源性产品，存在精液污染的潜在风险，而且它们的成分不均匀。 因此，迫切需要开发不含动物源性产品的新型培养基来保存精液。 然而，很难找到EY或牛奶的替代成分，因为EY和牛奶保护精子免受冷却，冷冻和储存损伤的机制仍不清楚。 在过去的六年中，我们提供的证据表明，EY的精子保护涉及EY低密度脂蛋白（LDL）与精浆蛋白的关联，这些蛋白对精子的储存不利。 这些最初在牛精浆中发现的有害蛋白（因此是BSP蛋白）具有从精子膜中提取脂质的潜力，从而对精子的保存能力产生不利影响。 然而，当这些BSP蛋白与LDL结合时，它们失去了从精子膜中提取脂质的能力，这是精子保护的起源（新概念）。 有趣的是，不含脂蛋白的脱脂牛奶在储存过程中也能保护精子。 因此，我们假设酪蛋白胶束和乳清蛋白，这是牛奶的主要成分结合BSP蛋白，这种相互作用是精子保护的关键。 目前的计划旨在了解蛋黄和牛奶保护精子的机制，这将有助于我们开发不含动物产品的商业应用的新型补充剂。