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排序方式: 共有804条查询结果,搜索用时 15 毫秒
81.
Early in ovarian differentiation, female mouse germ cells develop in clusters called oocyte nests or germline cysts. After birth, mouse germ cell nests break down into individual oocytes that are surrounded by somatic pregranulosa cells to form primordial follicles. Previously, we have shown that mice treated neonatally with genistein, the primary soy phytoestrogen, have multi-oocyte follicles (MOFs), an effect apparently mediated by estrogen receptor 2 (ESR2, more commonly known as ERbeta). To determine if genistein treatment leads to MOFs by inhibiting breakdown of oocyte nests, mice were treated neonatally with genistein (50 mg/kg per day) on Days 1-5, and the differentiation of the ovary was compared with untreated controls. Mice treated with genistein had fewer single oocytes and a higher percentage of oocytes not enclosed in follicles. Oocytes from genistein-treated mice exhibited intercellular bridges at 4 days of age, long after disappearing in controls by 2 days of age. There was also an increase in the number of oocytes that survived during the nest breakdown period and fewer oocytes undergoing apoptosis on Neonatal Day 3 in genistein-treated mice as determined by poly (ADP-ribose) polymerase (PARP1) and deoxynucleotidyl transferase mediated deoxyuridine triphosphate nick end-labeling (TUNEL). These data taken together suggest that genistein exposure during development alters ovarian differentiation by inhibiting oocyte nest breakdown and attenuating oocyte cell death. 相似文献
82.
Kwintkiewicz J Padilla-Banks E Jefferson WN Jacobs IM Wade PA Williams CJ 《Biology of reproduction》2012,86(3):1-8
Metastasis-associated protein 3 (MTA3) is a constituent of the Mi-2/nucleosome remodeling and deacetylase (NuRD) protein complex that regulates gene expression by altering chromatin structure and can facilitate cohesin loading onto DNA. The biological function of MTA3 within the NuRD complex is unknown. Herein, we show that MTA3 was expressed highly in granulosa cell nuclei of all ovarian follicle stages and at lower levels in corpora lutea. We tested the hypothesis that MTA3-NuRD complex function is required for granulosa cell proliferation. In the ovary, MTA3 interacted with NuRD proteins CHD4 and HDAC1 and the core cohesin complex protein RAD21. In cultured mouse primary granulosa cells, depletion of endogenous MTA3 using RNA interference slowed cell proliferation; this effect was rescued by coexpression of exogenous MTA3. Slowing of cell proliferation correlated with a significant decrease in cyclin B1 and cyclin B2 expression. Granulosa cell populations lacking MTA3 contained a significantly higher percentage of cells in G2/M phase and a lower percentage in S phase compared with control cells. Furthermore, MTA3 depletion slowed entry into M phase as indicated by reduced phosphorylation of histone H3 at serine 10. These findings provide the first evidence to date that MTA3 interacts with NuRD and cohesin complex proteins in the ovary in vivo and regulates G2/M progression in proliferating granulosa cells. 相似文献
83.
Macauley MS Chan J Zandberg WF He Y Whitworth GE Stubbs KA Yuzwa SA Bennet AJ Varki A Davies GJ Vocadlo DJ 《The Journal of biological chemistry》2012,287(34):28882-28897
The O-GlcNAc modification involves the attachment of single β-O-linked N-acetylglucosamine residues to serine and threonine residues of nucleocytoplasmic proteins. Interestingly, previous biochemical and structural studies have shown that O-GlcNAcase (OGA), the enzyme that removes O-GlcNAc from proteins, has an active site pocket that tolerates various N-acyl groups in addition to the N-acetyl group of GlcNAc. The remarkable sequence and structural conservation of residues comprising this pocket suggest functional importance. We hypothesized this pocket enables processing of metabolic variants of O-GlcNAc that could be formed due to inaccuracy within the metabolic machinery of the hexosamine biosynthetic pathway. In the accompanying paper (Bergfeld, A. K., Pearce, O. M., Diaz, S. L., Pham, T., and Varki, A. (2012) J. Biol. Chem. 287, 28865-28881), N-glycolylglucosamine (GlcNGc) was shown to be a catabolite of NeuNGc. Here, we show that the hexosamine salvage pathway can convert GlcNGc to UDP-GlcNGc, which is then used to modify proteins with O-GlcNGc. The kinetics of incorporation and removal of O-GlcNGc in cells occur in a dynamic manner on a time frame similar to that of O-GlcNAc. Enzymatic activity of O-GlcNAcase (OGA) toward a GlcNGc glycoside reveals OGA can process glycolyl-containing substrates fairly efficiently. A bacterial homolog (BtGH84) of OGA, from a human gut symbiont, also processes O-GlcNGc substrates, and the structure of this enzyme bound to a GlcNGc-derived species reveals the molecular basis for tolerance and binding of GlcNGc. Together, these results demonstrate that analogs of GlcNAc, such as GlcNGc, are metabolically viable species and that the conserved active site pocket of OGA likely evolved to enable processing of mis-incorporated analogs of O-GlcNAc and thereby prevent their accumulation. Such plasticity in carbohydrate processing enzymes may be a general feature arising from inaccuracy in hexosamine metabolic pathways. 相似文献
84.
Transforming growth factor beta (TGFβ) is a multipotent cytokine that is sequestered in the extracellular matrix (ECM) through interactions with a number of ECM proteins. The ECM serves to concentrate latent TGFβ at sites of intended function, to influence the bioavailability and/or function of TGFβ activators, and perhaps to regulate the intrinsic performance of cell surface effectors of TGFβ signal propagation. The downstream consequences of TGFβ signaling cascades in turn provide feedback modulation of the ECM. This review covers recent examples of how genetic mutations in constituents of the ECM or TGFβ signaling cascade result in altered ECM homeostasis, cellular performance and ultimately disease, with an emphasis on emerging therapeutic strategies that seek to capitalize on this refined mechanistic understanding. 相似文献
85.
Hunsaker TL Jefferson HS Morrison JK Franklin AJ Shewchuk BM 《Journal of molecular biology》2012,415(1):29-45
The human growth hormone gene (hGH-N) is regulated by a distal locus control region (LCR) composed of five deoxyribonuclease I hypersensitive sites (HSs). The region encompassing HSI and HSII contains the predominant pituitary somatotrope-specific hGH-N activation function of the LCR. This activity was attributed primarily to POU1F1 (Pit-1) elements at HSI, as linkage to HSI was sufficient for properly regulated hGH-N expression in transgenic mice, while HSII alone had no activity. However, the presence of HSII in conjunction with HSI further enhanced hGH-N transgene expression, indicating additional determinants of pituitary hGH-N activation in the HSII region, but limitations of transgenic models and previous ex vivo systems have prevented the characterization of HSII. In the present study, we employ a novel minichromosome model of the hGH-N regulatory domain and show that HSII confers robust POU1F1-dependent activation of hGH-N in this system. This effect was accompanied by POU1F1-dependent histone acetylation and methylation throughout the minichromosome LCR/hGH-N domain. A series of in vitro DNA binding experiments revealed that POU1F1 binds to multiple sites at HSII, consistent with a direct role in HSII function. Remarkably, POU1F1 binding was localized in part to the 3' untranslated region of a primate-specific LINE-1 (long interspersed nuclear element 1) retrotransposon, suggesting that its insertion during primate evolution may have conferred function to the HSII region in the context of pituitary GH gene regulation. These observations clarify the function of HSII, expanding the role of POU1F1 in hGH LCR activity, and provide insight on the molecular evolution of the LCR. 相似文献
86.
Leite CE Teixeira Ada C Cruz FF Concatto SC Amaral JH Bonan CD Campos MM Morrone FB Battastini AM 《Analytical biochemistry》2012,421(2):534-540
Zebrafish are currently used at various stages of the drug discovery process and can be a useful and cost-effective alternative to some mammalian models. Nitric oxide (NO) plays an important role in physiology of zebrafish. The availability of appropriate analytical techniques to quantify the NO is crucial for studying its role in physiological and pathological conditions. This work aimed at establishing a high-performance liquid chromatography method for determination of NO levels in zebrafish larvae. Attempts were also made to assess the normal levels of NO at the first days postfertilization and the possible changes under pathological conditions. The method validation was quantitatively evaluated in terms of sensitivity, specificity, precision, accuracy, linearity, and recovery. NO levels from zebrafish larvae at the first days postfertilization and larvae challenged to N(G)-nitro-L-arginine methyl ester, sodium nitroprusside, Escherichia coli lipopolysaccharide, and copper sulfate were analyzed. The samples were derivatized with 2,3-diaminonaphthalene, and fluorescence detection was used for the indirect determination of NO. The method showed a good performance for all validation parameters evaluated and was efficient to monitor changes in NO concentration under physiological and pathophysiological conditions. This method might represent a powerful tool to be applied in NO studies with zebrafish larvae. 相似文献
87.
Catalyzing denitrification of <Emphasis Type="Italic">Paracoccus versutus</Emphasis> by immobilized 1,5-dichloroanthraquinone 总被引:1,自引:0,他引:1
The accelerating effect of non-dissolved redox mediator (1,5-dichloroanthraquinone) on the biological denitrification was
investigated in this paper using 1,5-dichloroanthraquinone immobilized by calcium alginate (CA) and a heterotrophic denitrification
bacterium of Paracoccus versutus (GU111570). The results suggested that the denitrification rate was enhanced 2.1 fold by 25 mmol l−1 1,5-dichloroanthraquinone of this study, and a positive correlation was found for the denitrification rate and 1,5-dichloroanthraquinone
concentrations from 0 to 25 mmol l−1. According to the change characteristic of NO3
− and NO2
− during the denitrification process, the tentative accelerating mechanism of the denitrification by redox mediators was put
forward, and redox mediator might play the role of reduced cofactors like NADH, N(A)DH and SDH, or the similar ubiquinol/ubiquinone
(Q/QH2) role during the denitrification process. 相似文献
88.
Gilbert L Williamson KA Graves JA 《Proceedings. Biological sciences / The Royal Society》2012,279(1728):523-528
Mothers can non-genetically influence offspring phenotype in response to environmental conditions, including mate attractiveness. If such 'maternal effects' influence the offspring's reproduction and F2 generation, there is a mechanism for non-genetic trans-generational effects on phenotype, including epigenetic phenomena, with implications for evolution and population dynamics. We demonstrate in the zebra finch Taeniopygia guttata such non-genetic effects on offspring fecundity and the size of early stage F2 (eggs) in response to experimentally manipulated father's attractiveness. Our experimental design allowed us to deduce that the mechanism for this non-genetic paternal effect was via maternal investment in eggs. This affected female offspring size and, consequently, fecundity and F2 (egg) size. This demonstrates that female perception of mate attractiveness can have non-genetic, trans-generational fitness consequences and this may have important implications for the evolution of sexually selected traits and population dynamics. 相似文献
89.
Lipoteichoic acid is an important microbe-associated molecular pattern of Lactobacillus rhamnosus GG
Claes Ingmar JJ Segers Marijke E Verhoeven Tine LA Dusselier Michiel Sels Bert F De Keersmaecker Sigrid CJ Vanderleyden Jos Lebeer Sarah 《Microbial cell factories》2012,11(1):1-8
Background
Receptors with a single transmembrane (TM) domain are essential for the signal transduction across the cell membrane. NMR spectroscopy is a powerful tool to study structure of the single TM domain. The expression and purification of a TM domain in Escherichia coli (E.coli) is challenging due to its small molecular weight. Although ketosteroid isomerase (KSI) is a commonly used affinity tag for expression and purification of short peptides, KSI tag needs to be removed with the toxic reagent cyanogen bromide (CNBr).Result
The purification of the TM domain of p75 neurotrophin receptor using a KSI tag with the introduction of a thrombin cleavage site is described herein. The recombinant fusion protein was refolded into micelles and was cleaved with thrombin. Studies showed that purified protein could be used for structural study using NMR spectroscopy.Conclusions
These results provide another strategy for obtaining a single TM domain for structural studies without using toxic chemical digestion or acid to remove the fusion tag. The purified TM domain of p75 neurotrophin receptor will be useful for structural studies. 相似文献90.