Sperm motility is one of the major determinants of male fertility. Since sperm need a great deal of energy to support their fast movement by active metabolism, they are thus extremely vulnerable to oxidative damage by the reactive oxygen species (ROS) and other free radicals generated as byproducts in the electron transport chain. The present study is aimed at understanding the impact of a mitochondrial oxidizing/reducing microenvironment in the etiopathology of male infertility. We detected the mitochondrial DNA (mtDNA) 4,977 bp deletion in human sperm. We examined the gene mutation of ATP synthase 6 (ATPase6 m.T8993G) in ATP generation, the gene polymorphisms of uncoupling protein 2 (UCP2, G-866A) in the uncoupling of oxidative phosphorylation, the role of genes such as manganese superoxide dismutase (MnSOD, C47T) and catalase (CAT, C-262T) in the scavenging system in neutralizing reactive oxygen species, and the role of human 8-oxoguanine DNA glycosylase (hOGG1, C1245G) in 8-hydroxy-2-deoxyguanosine (8-OHdG) repair. We found that the sperm with higher motility were found to have a higher mitochondrial membrane potential and mitochondrial bioenergetics. The genotype frequencies of UCP2 G-866A, MnSOD C47T, and CAT C-262T were found to be significantly different among the fertile subjects, the infertile subjects with more than 50% motility, and the infertile subjects with less than 50% motility. A higher prevalence of the mtDNA 4,977 bp deletion was found in the subjects with impaired sperm motility and fertility. Furthermore, we found that there were significant differences between the occurrences of the mtDNA 4,977 bp deletion and MnSOD (C47T) and hOGG1 (C1245G). In conclusion, the maintenance of the mitochondrial redox microenvironment and genome integrity is an important issue in sperm motility and fertility.

中文翻译：

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维持线粒体微环境和精子容量的遗传关联

精子活力是男性生育能力的主要决定因素之一。由于精子需要大量能量来通过活跃的新陈代谢来支持其快速运动，因此它们极易受到活性氧 (ROS) 和作为电子传递链中副产物产生的其他自由基的氧化损伤。本研究旨在了解线粒体氧化/还原微环境对男性不育症病因病理学的影响。我们在人类精子中检测到线粒体 DNA (mtDNA) 4,977 bp 缺失。我们检测了 ATP 生成过程中 ATP 合酶 6 ( ATPase6 m.T8993G) 的基因突变，解偶联蛋白 2 ( UCP2的基因多态性, G-866A) 在氧化磷酸化的解偶联中, 锰超氧化物歧化酶 ( MnSOD , C47T) 和过氧化氢酶 ( CAT , C-262T) 等基因在清除系统中中和活性氧中的作用, 以及人类的作用8-氧鸟嘌呤 DNA 糖基化酶 ( hOGG1 , C1245G) 在 8-羟基-2-脱氧鸟苷 (8 - OHdG) 修复中。我们发现，具有较高运动能力的精子具有较高的线粒体膜电位和线粒体生物能量学。UCP2 G-866A、MnSOD C47T 和CAT的基因型频率发现 C-262T 在可育受试者、运动性超过 50% 的不育受试者和运动性低于 50% 的不育受试者之间存在显着差异。在精子活力和生育能力受损的受试者中发现 mtDNA 4,977 bp 缺失的发生率更高。此外，我们发现 mtDNA 4,977 bp 缺失与MnSOD (C47T) 和hOGG1 (C1245G) 之间存在显着差异。总之，线粒体氧化还原微环境和基因组完整性的维持是精子活力和生育力的重要问题。