Lysophospholipids, species-independent markers of pathological changes of spermatozoa

氧化应激导致的精子质量受损是指人类以及家畜和野生动物的生殖问题日益严重。在该项目的第一个研究阶段，人们试图利用质谱法为所有物种确定一个统一的脂质生物标志物。特别是溶血磷脂酰胆碱（LPC）由于其通过活性氧以及通过激活磷脂酶促进氧化脂肪酸分解而产生而受到青睐。然而，我们发现LPC仅在特定情况下积累，表明LPC可能不被用作统一的生物标志物。因此，据推测，LPC在射精中的积累是由一个迄今未知的机制。有数据表明LPC再乙酰化为磷脂酰胆碱（PC）和LPC降解为水溶性甘油磷酸胆碱（GPC）代表了具有巨大容量的高效途径。这是强调的事实，精浆确实提供了一个巨大的抗氧化潜力。因此，我们的建议是集中在进一步研究体内机制，防止LPC降解的精子样品中的不同物种和intra-individuals.We的目的是调查牛，猪和猫的精液与人类样品，因此前者确实含有醚脂质。后者的抗氧化潜力是迄今为止知之甚少。由于在最后一个研究期间获得的结果，重点需要不仅包括LPC生成的调查。据信，在ROS生成的过程中，产生了更高分子量的氧化产物（例如过氧化物或氯丹），这些更高分子量的脂质氧化产物的不稳定的酯键最有可能被磷脂酶水解，我们计划对其进行定量研究。应使用稳定同位素标记的分子（例如13 C标记的脂肪酸）检测LPC的再乙酰化和进一步转化为水溶性终产物。这些MS和NMR研究应嵌入其他方法中，如量热法（抗氧化潜力的测量），精子膜结构的生物物理测定，以分析病理过程中脂质组成的变化。预计可以获得病理过程中脂质组成变化的信息。此外，这些数据将有助于了解这些变化如何在物种特定水平上影响精子质量。

The impaired sperm quality as a consequence of oxidative stress refers to an increasing problem of reproduction in human as well as stock and wild life.Within the first research period of the project it has been tried to identify a unifying lipid biomarker for all species using mass spectrometry. Especially lysophosphatidylcholine (LPC) has been in favor due to its generation via reactive oxygen species as well as via activation of phospholipases to facilitate the breakdown of oxidized fatty acids. However, we revealed that LPC is accumulating under specific circumstances only, indicating the fact that LPC might not be used as the unifying biomarker. It is therefore assumed that the accumulation of LPC in ejaculates is prevented by a so far unknown mechanism. There are data that re-acetylation of LPC to phosphatidylcholine (PC) and degradation of LPC to water soluble glycerophosphorylcholine (GPC) representing highly effective pathways with huge capacities. This is underlined by the fact, that seminal plasma does provide an enormous anti oxidative potential.Hence, our proposal is focused to investigate further in-vivo mechanisms which do prevent degradation of LPC in sperm samples of various species and intra-individually.We aiming at investigation of cattle-, pig- and feline ejaculates in relation to human samples hence the former do contain ether lipids. The anti-oxidative potential of the latter is so far poorly understood.As a consequence of the results gained during the last research period the focus needs to include not only the investigation of LPC generation. It is believed that during the generation of ROS lipidoxidation products of higher molecular weight (e.g. peroxides or chlorhydrides) are generated.Unstable esther bondings of those lipid oxidation products of higher molecular weight are most probably hydrolyzed by phospholipases, which we are planning to investigate quantitatively. The detection of re-acetylation and further conversion to water soluble end-products of LPC shall be performed using stable isotope labelled molecules (e.g. 13C labelled fatty acids). Those MS- and NMR- investigations shall be embedded within other methods like calorimetry (measurement of anti-oxidative potential), biophysical determinations of sperm membrane structures to analyze the changes of the lipid composition during pathological processes. It is expected that information of lipid composition changes during pathologies can be gained. Furthermore these data will help to understand how those changes influence the sperm quality on a species specific level.