Novel phenotype of mouse spermatozoa following deletion of nine β-defensin genes

β-defensin peptides are a large family of antimicrobial peptides. Although they kill microbes in vitro and interact with immune cells, the precise role of these genes in vivo remains uncertain. Despite their inducible presence at mucosal surfaces, their main site of expression is the epididymis. Recent evidence suggests that a major function of these peptides is in sperm maturation. In addition to previous work suggesting this, work at the MRC Human Genetics Unit, Edinburgh, has shown that homozygous deletion of a cluster of nine β-defensin genes in the mouse results in profound male sterility. The spermatozoa derived from the mutants had reduced motility and increased fragility. Epididymal spermatozoa isolated from the cauda region of the homozygous mutants demonstrated precocious capacitation and increased spontaneous acrosome reactions compared with those from wild-types. Despite this, these mutant spermatozoa had reduced ability to bind to the zona pellucida of oocytes. Ultrastructural examination revealed a disintegration of the microtubule structure of mutant-derived spermatozoa isolated from the epididymal cauda region, but not from the caput. Consistent with premature acrosome reaction and hyperactivation, spermatozoa from mutant animals had significantly increased intracellular calcium content. This work demonstrates that in vivo β-defensins are essential for successful sperm maturation, and that their disruption alters intracellular calcium levels, which most likely leads to premature activation and spontaneous acrosome reactions that result in hyperactivation and loss of microtubule structure of the axoneme. Determining which of the nine genes are responsible for the phenotype and the relevance to human sperm function is important for future work on male infertility.     

Comparison of DNA fragmentation levels in spermatozoa with different sex chromosome complements

Research question

Do spermatozoa with different sex chromosome complements (X and Y; aneuploidy and monosomy) exhibit different degrees of DNA damage?

Tangeretin ameliorates erectile and testicular dysfunction in a rat model of hypertension

Tangeretin is a polymethoxyflavone concentrated in citrus peels and has several biological activities. This study examined whether tangeretin improved reproductive dysfunction in N^ω-nitro-L-arginine methyl ester hydrochloride (L-NAME)-induced hypertensive rats. Male Sprague-Dawley rats received L-NAME to induce hypertension and reproductive dysfunction for 5 w and were treated with tangeretin (15 or 30 mg/kg) or sildenafil citrate (10 mg/kg) for the final two weeks. Mean arterial pressure (MAP), intracavernosal pressure (ICP) response to cavernous nerve stimulation, endothelial nitric oxide synthase (eNOS), Angiotensin II receptor type 1 (AT₁R) and gp91^phox protein expressions and malondialdehyde (MDA) level in penile tissues were measured. Sperm concentrations and motility, seminiferous tubule morphology, serum testosterone, testicular eNOS and steroidogenic acute regulatory protein (StAR) expression were evaluated. Aortic superoxide generation, plasma and testicular MDA and plasma nitrate/nitrite levels were determined. Tangeretin reduced blood pressure and increased the maximum ICP/MAP associated with suppression of AT₁R/gp91phox and upregulation of eNOS expression in hypertensive rats (P < 0.05). Furthermore, improvement of sperm quality relevant to increased testicular eNOS and StAR expression was found in tangeretin treated rats (P < 0.05). Changes in seminiferous tubule morphology in hypertensive rats were recovered by tangeretin (P < 0.05). It increased testosterone levels and reduced oxidative stress biomarkers and raised plasma nitrate/nitrite levels in L-NAME rats (P < 0.05). In conclusion, tangeretin improved maximum ICP/MAP and testicular dysfunction and morphology in rats treated with L-NAME. The molecular mechanisms are mediated by modulations of penile eNOS and AT₁R/gp91^phox expressions and testicular eNOS and StAR expression.     

Consistent age-dependent declines in human semen quality: A systematic review and meta-analysis

Reduced fertility typically occurs among women in their late 30s, but increasing evidence indicates that advanced paternal age is associated with changes in reproduction as well. Numerous studies have investigated age-based declines in semen traits, but the impact of paternal age on semen parameter values remains inconclusive. Using data from 90 studies (93,839 subjects), we conducted a systematic review and meta-analysis to quantify the effect of male age on seven ejaculate traits (semen volume, sperm concentration, total sperm count, morphology, total motility, progressive motility and DNA fragmentation). Age-associated declines in semen volume, percentage motility, progressive motility, normal morphology and unfragmented cells were statistically significant and results generally seemed to be robust against confounding factors. Unexpectedly, sperm concentration did not decline with increasing male age, even though we found that sperm concentration declined over time. Our findings indicate that male age needs more recognition as a potential contributor to the negative pregnancy outcomes and reduced offspring health associated with delayed first reproduction. We suggest that greater focus on collection of DNA fragmentation and progressive motility in a clinical setting may lead to better patient outcomes during fertility treatments of aging couples.     

Characterization of membrane occupation and recognition nexus repeat containing 3, meiosis expressed gene 1 binding partner,in mouse male germ cells

Mammalian spermatogenesis is a well-organized process of cell development and differentiation. Meiosis expressed gene 1 (MEIG1) plays an essential role in the regulation of spermiogenesis. To explore potential mechanisms of MEIG1''s action, a yeast two-hybrid screen was conducted, and several potential binding partners were identified; one of them was membrane occupation and recognition nexus repeat containing 3 (MORN3). MORN3 mRNA is only abundant in mouse testis. In the testis, Morn3 mRNA is highly expressed in the spermiogenesis stage. Specific anti-MORN3 polyclonal antibody was generated against N-terminus of the full-length MORN3 protein, and MORN3 expression and localization was examined in vitro and in vivo. In transfected Chinese hamster ovary cells, the antibody specifically crossed-reacted the full-length MORN3 protein, and immunofluorescence staining revealed that MORN3 was localized throughout the cytoplasm. Among multiple mouse tissues, about 25 kDa protein, was identified only in the testis. The protein was highly expressed after day 20 of birth. Immunofluorescence staining on mixed testicular cells isolated from adult wild-type mice demonstrated that MORN3 was expressed in the acrosome in germ cells throughout spermiogenesis. The protein was also present in the manchette of elongating spermatids. The total MORN3 expression and acrosome localization were not changed in the Meig 1-deficient mice. However, its expression in manchette was dramatically reduced in the mutant mice. Our studies suggest that MORN3 is another regulator for spermatogenesis, probably together with MEIG1.     

ICSI联合IVM技术在卵巢低反应高龄患者中的应用

目的：探讨胞浆内单精子注射（ICSI）联合未成熟卵母细胞体外成熟（IVM）技术在卵巢低反应高龄患者中的应用价值。方法：回顾性分析2016年1月—2018年9月于郑州大学第一附属医院生殖医学中心行ICSI助孕治疗81个周期，年龄≥35岁，获卵数≤3个，且卵母细胞均未成熟。按促排卵方案分为微刺激方案组（n=37）和拮抗剂方案组（n=44），统计2组患者基础情况、实验室结果及妊娠结局。结果：①2组患者年龄、不孕时间、基础内分泌、基础窦卵泡数及抗苗勒管激素（AMH）比较，差异均无统计学意义（P＞0.05）；②拮抗剂方案组Gn总量较微刺激方案组高，差异有统计学意义（P＜0.05）；③微刺激方案组与拮抗剂方案组体外培养成熟率、2PN率、卵裂率、可利用胚胎率及优胚率比较差异均无统计学意义（P＞0.05）；④微刺激方案组与拮抗剂方案组的胚胎存活率、种植率和临床妊娠率比较差异无统计学意义（P＞0.05）。结论：对于卵巢低反应的高龄患者行ICSI联合IVM培养有利于提高卵母细胞成熟率及胚胎利用率，增加妊娠机会，微刺激方案Gn用量少对卵巢低反应患者是经济有效的选择。     

间歇低氧对小鼠精子生成数量及活力的影响

目的：探讨间歇低氧对小鼠精子生成数量及活力的影响。方法将24只C57BL/6J雄性小鼠随机分为对照组和间歇低氧组，间歇低氧组置于自制的低氧舱中，舱内循环充入氮气和压缩空气，舱内氧浓度最高为（21±0.5）%、最低为（5±0.5）%，每次循环90 s，每天低氧8h；对照组置于与间断低氧舱相似的舱内，舱内循环充入洁净压缩空气。12周后将小鼠处死，测定各组小鼠的睾丸重、附睾重、精子数及精子活力。结果与对照组相比，间歇低氧组小鼠睾丸重、附睾重、精子生成的数量及活力均下降（P＜0.05）。结论间歇低氧能降低小鼠精子生成的数量及活力。