Search Results
You are looking at 1 - 10 of 110 items for
- Author: Yang Yang x
- Refine by access: Content accessible to me x
Search for other papers by K Yang in
Google Scholar
PubMed
During mammalian pregnancy, the circulating concentration of cortisol (in rodents, corticosterone) in the mother is much higher than that in the fetus. Since the placenta is the only barrier, apart from the uterus, between the mother and her fetus, this gradient in cortisol concentrations suggests that there is a placental barrier preventing maternal cortisol from crossing into the fetus. The intracellular enzyme 11 beta-hydroxysteroid dehydrogenase (11 beta-HSD) is an ideal candidate for this barrier because it interconverts cortisol and corticosterone to their inactive metabolites cortisone and 11-dehydrocorticosterone. Indeed, 11 beta-HSD enzyme is expressed in the placenta of humans and a range of other animal species. Moreover, it is well positioned to serve as the barrier since it is localized to the syncytiotrophoblast, the site of maternal-fetal exchange. Given that fetal exposure to excessive amounts of glucocorticoids leads to intrauterine growth retardation, it has been hypothesized that the physiological significance of this placental 11 beta-HSD barrier is to protect the fetus from adverse effects of maternal glucocorticoids.
Search for other papers by Yang Gao in
Google Scholar
PubMed
Search for other papers by Haixia Wen in
Google Scholar
PubMed
Search for other papers by Chao Wang in
Google Scholar
PubMed
Search for other papers by Qinglei Li in
Google Scholar
PubMed
Transforming growth factor β (TGFβ) superfamily signaling is essential for female reproduction. Dysregulation of the TGFβ signaling pathway can cause reproductive diseases. SMA and MAD (mothers against decapentaplegic) (SMAD) proteins are downstream signaling transducers of the TGFβ superfamily. SMAD7 is an inhibitory SMAD that regulates TGFβ signaling in vitro. However, the function of SMAD7 in the ovary remains poorly defined. To determine the signaling preference and potential role of SMAD7 in the ovary, we herein examined the expression, regulation, and function of SMAD7 in mouse granulosa cells. We showed that SMAD7 was expressed in granulosa cells and subject to regulation by intraovarian growth factors from the TGFβ superfamily. TGFB1 (TGFβ1), bone morphogenetic protein 4, and oocyte-derived growth differentiation factor 9 (GDF9) were capable of inducing Smad7 expression, suggesting a modulatory role of SMAD7 in a negative feedback loop. Using a small interfering RNA approach, we further demonstrated that SMAD7 was a negative regulator of TGFB1. Moreover, we revealed a link between SMAD7 and GDF9-mediated oocyte paracrine signaling, an essential component of oocyte–granulosa cell communication and folliculogenesis. Collectively, our results suggest that SMAD7 may function during follicular development via preferentially antagonizing and/or fine-tuning essential TGFβ superfamily signaling, which is involved in the regulation of oocyte–somatic cell interaction and granulosa cell function.
Search for other papers by Y. Q. Yang in
Google Scholar
PubMed
Search for other papers by X. Y. Wu in
Google Scholar
PubMed
Summary. Gossypol acetic acid was administered orally (30, 60, 90 and 120 mg/kg/day) on Days 1–5 post coitum to mature female rats. At autopsy on Day 10, pregnancy in most treated animals (6/7 and 6/8) was blocked at high doses (90 and 120 mg/kg/day respectively). As the daily dose decreased to 60 mg/kg/day half (4/8) were not pregnant. However, at a lower dose (30 mg/kg/day), or at a single dose of 200 mg/kg at Day 1 p.c., pregnancy was not blocked. The concentrations of progesterone in the serum of these females were significantly decreased except at the low dose. The numbers of implantation sites in the treated females that did remain pregnant were similar to those in control females except at the dose of 120 mg/kg/day. Gossypol did not retard the development of the preimplantation embryo or cavitation. The Pontamine Blue test revealed that the drug did not interfere with the initiation of implantation. We suggest that gossypol has an antifertility effect in the female rat because it is luteolytic and disrupts post-implantation development.
Search for other papers by C. H. Yang in
Google Scholar
PubMed
Search for other papers by P. N. Srivastava in
Google Scholar
PubMed
Summary.
High concentrations of α-chlorohydrin were found to inhibit hyaluronidase, β-glucuronidase, and aryl sulphatases in bull and rabbit spermatozoa, but not acrosin and neuraminidase. Preincubation of the enzyme and α-chlorohydrin was essential to achieve the maximum inhibition which was irreversible.
Search for other papers by CHUL HAK YANG in
Google Scholar
PubMed
Search for other papers by P. N. SRIVASTAVA in
Google Scholar
PubMed
Summary.
Ram sperm acrosomes were disrupted by Hyamine and Triton treatment and extracts were initially fractionated with a Sephadex G-100 column at pH 3·5. Acrosin, a proteolytic enzyme, was completely separated from hyaluronidase by this step. Highly active hyaluronidase, specific activity of 1320 units/mg protein (38,280 National Formulary units/mg protein), was obtained by DEAE chromatography but two minor contaminants were present. The partially purified enzyme had an optimum at pH 4·3. The enzyme showed no activity at pH 3·0 and only 10% of its activity at pH 8·0. Heparin and chondroitin sulphate B inhibited 50% of its activity. The molecular weight was estimated to be 62,000 by sodium dodecyl sulphate gel electrophoresis.
Search for other papers by Zoe A Wilson in
Google Scholar
PubMed
Search for other papers by Caiyun Yang in
Google Scholar
PubMed
Although the process of gamete formation in plants has many unique features, much has been learnt from the comparative analysis between plants and other eukaryotic systems. Plants have a number of factors that have made them desirable for the analysis of gamete development; these include late germline specification, the non-lethality of mutations affecting gamete development and the large size of their chromosomes. The availability of the fully annotated Arabidopsis genome and comparative analysis using yeast, animal and E. coli has led to the identification and functional characterisation of many genes with roles in gamete development, principally those associated with meiosis, recombination and DNA repair. The advantages that plants give with the use of mutant screens to identify genes associated with gamete formation have also provided access to genes that are difficult to characterise by alternative routes. This has yielded novel information regarding the processes of gamete formation in higher plants. The times may now be changing with the advantages that plants provide serving to advance knowledge of gamete formation in other eukaryotic systems.
Search for other papers by Jingmei Hou in
Google Scholar
PubMed
Search for other papers by Shi Yang in
Google Scholar
PubMed
Search for other papers by Hao Yang in
Google Scholar
PubMed
Search for other papers by Yang Liu in
Google Scholar
PubMed
Search for other papers by Yun Liu in
Google Scholar
PubMed
Search for other papers by Yanan Hai in
Google Scholar
PubMed
Search for other papers by Zheng Chen in
Google Scholar
PubMed
Search for other papers by Ying Guo in
Google Scholar
PubMed
Search for other papers by Yuehua Gong in
Google Scholar
PubMed
Search for other papers by Wei-Qiang Gao in
Google Scholar
PubMed
Search for other papers by Zheng Li in
Google Scholar
PubMed
State Key Laboratory of Oncogenes and Related Genes, Department of Urology, Shanghai Key Laboratory for Assisted Reproduction and Reproductive Genetics, Shanghai Key Laboratory of Reproductive Medicine, Stem Cell Research Center, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, 1630 Dongfang Road, Shanghai 200127, China
State Key Laboratory of Oncogenes and Related Genes, Department of Urology, Shanghai Key Laboratory for Assisted Reproduction and Reproductive Genetics, Shanghai Key Laboratory of Reproductive Medicine, Stem Cell Research Center, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, 1630 Dongfang Road, Shanghai 200127, China
State Key Laboratory of Oncogenes and Related Genes, Department of Urology, Shanghai Key Laboratory for Assisted Reproduction and Reproductive Genetics, Shanghai Key Laboratory of Reproductive Medicine, Stem Cell Research Center, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, 1630 Dongfang Road, Shanghai 200127, China
Search for other papers by Zuping He in
Google Scholar
PubMed
Infertility is a major and largely incurable disease caused by disruption and loss of germ cells. It affects 10–15% of couples, and male factor accounts for half of the cases. To obtain human male germ cells ‘especially functional spermatids’ is essential for treating male infertility. Currently, much progress has been made on generating male germ cells, including spermatogonia, spermatocytes, and spermatids, from various types of stem cells. These germ cells can also be used in investigation of the pathology of male infertility. In this review, we focused on advances on obtaining male differentiated germ cells from different kinds of stem cells, with an emphasis on the embryonic stem (ES) cells, the induced pluripotent stem (iPS) cells, and spermatogonial stem cells (SSCs). We illustrated the generation of male differentiated germ cells from ES cells, iPS cells and SSCs, and we summarized the phenotype for these stem cells, spermatocytes and spermatids. Moreover, we address the differentiation potentials of ES cells, iPS cells and SSCs. We also highlight the advantages, disadvantages and concerns on derivation of the differentiated male germ cells from several types of stem cells. The ability of generating mature and functional male gametes from stem cells could enable us to understand the precise etiology of male infertility and offer an invaluable source of autologous male gametes for treating male infertility of azoospermia patients.
Search for other papers by Wen-Ming Ma in
Google Scholar
PubMed
Search for other papers by Ye-Qing Qian in
Google Scholar
PubMed
Search for other papers by Mo-Ran Wang in
Google Scholar
PubMed
Search for other papers by Fan Yang in
Google Scholar
PubMed
Search for other papers by Wei-Jun Yang in
Google Scholar
PubMed
As the distal part of the crustacean male reproductive tract, terminal ampullae play important roles in sperm development and storage of mature spermatophores. In the present study, the novel gene terminal ampullae peptide (TAP) was cloned from terminal ampullae of the prawn, Macrobrachium rosenbergii. The cDNA sequence consists of 768 nucleotides, with an open-reading frame of 264 nucleotides which encodes a putative 88-amino acid precursor protein with a 17-amino acid residue signal peptide. Western blotting and immunohistochemical analysis revealed that TAP was distributed on terminal ampullae and sperm, and its expression was related to gonad development. To elucidate the functional role of TAP in vivo, we disrupted the TAP gene by RNA interference (RNAi) and evaluated the effect on fertility and several sperm parameters. Although there was no difference in fertility between RNAi-induced prawns and controls, RNAi treatment decreased the sperm gelatinolytic activity and blocked proteolytic activity on the vitelline coat. These data provide evidence that TAP participates in regulating sperm proteolytic activity, and performs a crucial role in sperm maturation and degradation of the vitelline coat during fertilization.
Departments of, Biology, Obstetrics and Gynecology, Medicine, Centre for the Study of Reproduction, McGill University, Research Institute of the McGill University Health Centre, Montréal, Quebec, Canada
Search for other papers by Enas Mahrous in
Google Scholar
PubMed
Departments of, Biology, Obstetrics and Gynecology, Medicine, Centre for the Study of Reproduction, McGill University, Research Institute of the McGill University Health Centre, Montréal, Quebec, Canada
Search for other papers by Qin Yang in
Google Scholar
PubMed
Departments of, Biology, Obstetrics and Gynecology, Medicine, Centre for the Study of Reproduction, McGill University, Research Institute of the McGill University Health Centre, Montréal, Quebec, Canada
Departments of, Biology, Obstetrics and Gynecology, Medicine, Centre for the Study of Reproduction, McGill University, Research Institute of the McGill University Health Centre, Montréal, Quebec, Canada
Search for other papers by Hugh J Clarke in
Google Scholar
PubMed
Oocytes accumulate an enormous quantity of mitochondrial (mt) DNA, and an insufficient amount of mtDNA may underlie some cases of poor oocyte quality leading to infertility. Little is known, however, about the mechanisms that govern the timing and regulation of mtDNA accumulation during oogenesis. We report, through analysis of the mtDNA content of individual oocytes of the mouse, that mtDNA accumulates steadily during oocyte growth to reach a value of ∼175 000 copies per cell. MtDNA content ceases to increase once oocytes reach full size and remains unchanged during meiotic maturation. To test whether mtDNA accumulation depends on oocyte growth, we inhibited growth in vitro in two ways – by exposing complexes comprising partially grown oocytes enclosed by granulosa cells to a chemical inhibitor of the phosphatidylinositol-3-kinase signaling pathway and by removing the surrounding granulosa cells from partially grown oocytes. Under both conditions, the oocytes fail to grow, but mtDNA accumulation is unaffected, indicating that the two processes can be mechanistically uncoupled. Quantitative analysis of the mRNAs encoding proteins required for mtDNA replication revealed that Polg (Polga) (polymerase-γ, α-subunit), Polg2 (Polgb), and Tfam (transcription factor A, mitochondrial) increase during oocyte growth but then decrease after fully grown oocytes become transcriptionally silent as indicated by the non-surrounded nucleolus-to-surrounded nucleolus transition. Thus, there is a correlation between the decline in the quantity of mRNAs encoding mtDNA replication factors in fully grown oocytes and the arrest of mtDNA accumulation in these cells, suggesting that the two events may be causally linked.
Search for other papers by Zhangsheng Yang in
Google Scholar
PubMed
Search for other papers by Hirotaka Yoshioka in
Google Scholar
PubMed
Search for other papers by John R McCarrey in
Google Scholar
PubMed
The phosphoglycerate kinase-2 (Pgk2) gene is regulated in a tissue-, cell type-, and developmental stage-specific manner during spermatogenesis and is required for normal sperm motility and fertility in mammals. Activation of Pgk2 transcription is regulated by testis-specific demethylation of DNA and binding of testis-specific transcription factors to enhancer and core promoter elements. Here, we show that chromatin remodeling including reconfiguration of nucleosomes and changes in histone modifications is also associated with transcriptional activation of the Pgk2 gene during spermatogenesis. Developmental studies indicate that the order of events involved in transcriptional activation of the Pgk2 gene includes demethylation of DNA in T1- and T2-prospermatogonia, binding of a factor to the CAAT box in type A and B spermatogonia, followed by recruitment of chromatin remodeling factors, displacement of a nucleosome from the Pgk2 promoter region, binding of factors to the Pgk2 core promoter and enhancer regions, and, finally, initiation of transcription in primary spermatocytes. Transgene studies show that Pgk2 core promoter elements are required to direct demethylation of DNA and reconfiguration of nucleosomes, whereas both enhancer and core promoter elements are required to direct changes in histone modifications and initiation of transcription. These results provide novel insight into the developmental order of molecular events required to activate tissue-specific transcription of the Pgk2 gene, the distinct elements in the 5′-regulatory region of the Pgk2 gene that regulate each of these events, and the relationship among these events in that each step in this process appears to be a necessary prerequisite for the subsequent step.