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Jing Tong, Shile Sheng, Yun Sun, Huihui Li, Wei-Ping Li, Cong Zhang and Zi-Jiang Chen

Good-quality oocytes are critical for the success of in vitro fertilization (IVF), but, to date, there is no marker of ovarian reserve available that can accurately predict oocyte quality. Melatonin exerts its antioxidant actions as a strong radical scavenger that might affect oocyte quality directly as it is the most potent antioxidant in follicular fluid. To investigate the precise role of endogenous melatonin in IVF outcomes, we recruited 61 women undergoing treatment cycles of IVF or intracytoplasmic sperm injection (ICSI) procedures and classified them into three groups according to their response to ovarian stimulation. Follicular fluid was collected to assess melatonin levels using a direct RIA method. We found good correlations between melatonin levels in follicular fluid with age, anti-Müllerian hormone (AMH) and baseline follicle-stimulating hormone (bFSH), all of which have been used to predict ovarian reserve. Furthermore, as melatonin levels correlated to IVF outcomes, higher numbers of oocytes were collected from patients with higher melatonin levels and consequently the number of oocytes fertilized, zygotes cleaved, top quality embryos on D3, blastocysts obtained and embryos suitable for transplantation was higher. The blastocyst rate increased in concert with the melatonin levels across the gradient between the poor response group and the high response group. These results demonstrated that the melatonin levels in follicular fluid is associated with both the quantity and quality of oocytes and can predict IVF outcomes as well making them highly relevant biochemical markers of ovarian reserve.

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Yun-Kao Cao, Zhi-Sheng Zhong, Da-Yuan Chen, Gui-Xue Zhang, Heide Schatten and Qing-Yuan Sun

The small GTPase Ran controls numerous cellular processes of the mitotic cell cycle. In this experiment, we investigated the localization and possible roles of Ran during mouse oocyte meiotic maturation, fertilization and early cleavage by using confocal laser scanning microscopy, antibody microinjection and microtubule disturbance. The results showed that Ran was localized mainly in the nucleus (except for the nucleolus) in the oocyte, zygote and early embryo. At pro-metaphase of meiosis I, Ran distributed throughout the cell, but predominantly concentrated around the condensed chromosomes. During the completion of meiosis I and meiosis II, it concentrated to the meiotic spindle microtubules except for the midbody region. After sperm penetration, Ran dispersed with the extrusion of the second polar body and gradually concentrated in the male and female pronuclei thereafter. Ran was also observed to exist diffusely in the cytoplasm in prophase; it concentrated at the mitotic spindle, and migrated to the nucleus during early cleavage. Ran’s concentration around the spindle disappeared when microtubule assembly was inhibited by colchicine, while it was concentrated around the chromosomes after microtubule stabilization with taxol treatment. Ran did not display any role in cytokinesis during division when pseudo-cleavage of germinal vesicle-intact oocytes was induced. Anti-Ran antibody microinjection decreased the germinal vesicle breakdown and the first polar body extrusion, and distorted spindle organization and chromosome alignment. Our results indicate that Ran has a cell cycle-dependent localization and may have regulatory roles in cell cycle progression and microtubule organization in mouse oocytes, fertilized eggs and early embryos.

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Xiao-Qian Meng, Ke-Gang Zheng, Yong Yang, Man-Xi Jiang, Yan-Ling Zhang, Qing-Yuan Sun and Yun-Long Li

Microfilaments (actin filaments) regulate various dynamic events during meiotic maturation. Relatively, little is known about the regulation of microfilament organization in mammalian oocytes. Proline-rich tyrosine kinase2 (Pyk2), a protein tyrosine kinase related to focal adhesion kinase (FAK) is essential in actin filaments organization. The present study was to examine the expression and localization of Pyk2, and in particular, its function during rat oocyte maturation. For the first time, by using Western blot and confocal laser scanning microscopy, we detected the expression of Pyk2 in rat oocytes and found that Pyk2 and Try402 phospho-Pyk2 were localized uniformly at the cell cortex and surrounded the germinal vesicle (GV) or the condensed chromosomes at the GV stage or after GV breakdown. At the metaphase and the beginning of anaphase, Pyk2 distributed asymmetrically both in the ooplasm and the cortex with a marked staining associated with the chromosomes and the region overlying the meiotic spindle. At telophase, Pyk2 was observed in the cleavage furrows in addition to its cortex and cytoplasm localization. The dynamics of Pyk2 were similar to that of F-actin, and this kinase was found to co-localize with microfilaments in several developmental stages during rat oocyte maturation. Microinjection of Pyk2 antibody demolished the microfilaments assembly and also inhibited the first polar body (PB1) emission. These findings suggest an important role of Pyk2 for rat oocyte maturation by regulating the organization of actin filaments.

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Na-Ra Han, Chan-Lee Park, Na-Rae Kim, Hee-Yun Kim, Myoung-Schook Yoou, Sun-Young Nam, Phil-Dong Moon, Hyun-Ja Jeong and Hyung-Min Kim

Menopause is a significant physiological phase that occurs as women's ovaries stop producing ovum and the production of estrogen declines. Human placenta and some amino acids are known to improve menopausal symptoms. In this study, we investigated that porcine placenta extract (PPE) and arginine (Arg), a main amino acid of PPE, would have estrogenic activities in ovariectomized (OVX) mice as a menopause mouse model, human breast cancer cell line (MCF-7) cells, and human osteoblast cell line (MG-63) cells. PPE or Arg significantly inhibited the body weight and increased the vagina weight compared to the OVX mice. PPE or Arg ameliorated the vaginal atrophy in the OVX mice. The levels of 17β-estradiol and the activities of alkaline phosphatase (ALP) were significantly increased by PPE or Arg in the serum of OVX mice. Trabecular bone parameters such as bone mineral density and porosity were also improved by PPE or Arg in the OVX mice. In the MCF-7 and MG-63 cells, PPE or Arg significantly increased the cell proliferation, estrogen receptor β mRNA expression, and estrogen-response elements luciferase activity. Finally, PPE or Arg increased the activations of ALP and extracellular signal-regulated kinase 1/2 in the MG-63 cells. These results indicate that PPE or Arg would have estrogenic and osteoblastic activity. Therefore, PPE or Arg may be useful as new pharmacological tools for treating menopausal symptoms including osteoporosis.

Free Korean abstract: A Korean translation of this abstract is freely available at http://www.reproduction-online.org/content/150/3/173/suppl/DC1.

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Na-Ra Han, Chan-Lee Park, Na-Rae Kim, Hee-Yun Kim, Myoung-Schook Yoou, Sun-Young Nam, Phil-Dong Moon, Hyun-Ja Jeong and Hyung-Min Kim

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Chencheng Yao, Yun Liu, Min Sun, Minghui Niu, Qingqing Yuan, Yanan Hai, Ying Guo, Zheng Chen, Jingmei Hou, Yang Liu and Zuping He

Spermatogenesis is composed of three distinctive phases, which include self-renewal of spermatogonia via mitosis, spermatocytes undergoing meiosis I/II and post-meiotic development of haploid spermatids via spermiogenesis. Spermatogenesis also involves condensation of chromatin in the spermatid head before transformation of spermatids to spermatozoa. Epigenetic regulation refers to changes of heritably cellular and physiological traits not caused by modifications in the DNA sequences of the chromatin such as mutations. Major advances have been made in the epigenetic regulation of spermatogenesis. In this review, we address the roles and mechanisms of epigenetic regulators, with a focus on the role of microRNAs and DNA methylation during mitosis, meiosis and spermiogenesis. We also highlight issues that deserve attention for further investigation on the epigenetic regulation of spermatogenesis. More importantly, a thorough understanding of the epigenetic regulation in spermatogenesis will provide insightful information into the etiology of some unexplained infertility, offering new approaches for the treatment of male infertility.

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Eugine Lee, Yeon Ik Jeong, Seon Mi Park, Jong Yun Lee, Ji Hye Kim, Sun Woo Park, M S Hossein, Yeon Woo Jeong, Sue Kim, Sang Hwan Hyun and Woo Suk Hwang

In an effort to improve the quality of in vitro produced porcine embryos, we investigated the effect of brain-derived neurotropic factor (BDNF), a neurotropin family member, on in vitro maturation (IVM) of porcine oocytes. The expression of BDNF and truncated isoforms of its receptor, tyrosine kinase B (TrkB), and p75 common neurotropin receptor was detected in both follicular cells and metaphase-I stage oocytes by RT-PCR. However, mRNA of full-length TrkB was not found in oocytes although it was detected in follicular cells. The expression pattern of BDNF and TrkB was confirmed by immunohistochemistry. Supplementation with BDNF (30 ng/ml) during IVM significantly (P < 0.05) increased the first polar body extrusion and glutathione levels in oocytes, whereas the effect of BDNF on nuclear maturation was diminished when gonadotropin and epidermal growth factor (EGF) were added to the culture media. However, treatment with BDNF (30 ng/ml) along with EGF (10 ng/ml) in the presence of gonadotropin significantly (P < 0.05) increased the developmental competence of oocytes to the blastocyst stage after both in vitro fertilization (IVF; 29.1% when compared with control, 15.6%) and somatic cell nuclear transfer (SCNT; 13.6% when compared with control, 3%). This appeared to reflect a stimulatory interaction between BDNF and EGF to enhance the cytoplasmic maturation of oocytes to support successful preimplantation development. In conclusion, BDNFenhanced nuclearand cytoplasmic maturation of oocytes by autocrine and/or paracrine signals. Also, when used together with EGF, BDNF increased the developmental potency of embryos after IVF and SCNT, demonstrating an improved in vitro production protocol for porcine oocytes.