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HH Ortega NR Salvetti C Baravalle JA Lorente GA Mira 《Reproduction in domestic animals》2006,41(3):204-209
The objectives of this work were to determine the changes in the expression of neuroendocrine markers in Leydig cell by oestradiol treatment, and to determine whether testosterone is able to recover partially the effects of hormonal suppression induced by oestradiol. Adult male rats were injected daily with either 50 microg of oestradiol or oestradiol plus testosterone propionate (25 mg every 3 days) for 15 days. The animals were sacrificed and testicles were dissected and processed by routine histological protocols. FSH and LH serum levels were determined by radioimmunoassay. The visualization of antigens was achieved by the streptavidin-peroxidase immunohistochemical method. Antibodies against chromogranin A (CrA), S-100 protein (S-100), P substance (PS), synaptofisin (SYN), neurofilament protein (NF), gliofibrillary acidic protein (GFAP) and neuron specific enolase (NSE) were used. The mean LH and FSH serum concentrations were consistently suppressed with hormonal treatments. Intermediate filaments (NF and GFAP) showed no difference in their expression. The expression of S-100, NSE and SYN was significantly lower in both hormone-treated groups. In oestradiol-treated rats, the immunoreactivity of CrA and SP decreased significantly but was restored after testosterone supplementation. Although the nature and functions of many of these substances in Leydig cells remain unknown, these results are consistent with the hypothesis that the expression of some neuroendocrine markers is hormonally controlled. 相似文献
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Mira Fine Edna Sakal Dorit Vashdi Nava Chapnik-Cohen Violet Daniel Avigdor Levanon Orli Lipshitz Arieh Gertler 《Fish physiology and biochemistry》1993,11(1-6):353-361
Carp growth hormone (cGH) cDNA, in which Cys-123 was mutated to Ala, was prepared, transferred to the expression vector, expressed
in Escherichia coli and the mutant was purified to homogeneity. The mutation only slightly improved yield of the monomeric fraction, indicating
that Cys-123 is not involved in improper refolding. As compared to cGH, the mutant (cGH-C123A) exhibited lower binding affinity
toward homologous liver receptors and lower bioactivity in a 3T3-F442A preadipocyte bioassay despite the fact that both hormones
exhibited almost identical cross-reactivity with anti-cGH antibodies. These results, along with those of a structural comparison
to hGH, suggest that Cys-123 is located in the hydrophobic core of the hormone, and is most likely affecting the conformation
of the binding site. Dimeric forms of the hormone and its mutant were less active than their respective monomers. Homologous
binding experiments using a carp liver microsomal fraction revealed a single receptor population with Kd = 0.77 nM and Bmax = 241 fmol/mg microsomal protein.
Résumé Un ADN complémentaire (cDNA) de l'hormone de croissance de carpe (cGH), dans lequel l'acide aminé Cys-123 a été muté en Ala, a été préparé, inséré dans un vecteur d'expression, et exprimé dans Escherichia coli. Le mutant a ensuite été purifié jusqu'à homogénéité. La mutation améliore seulement faiblement la production de la fraction monomérique, indiquant que le Cys-123 n'est pas impliqué dans un repliement erroné. Comparé à la cGH, sa forme mutée (cGH-C123A) montre une plus faible affinité de liaison vis à vis de récepteurs hépatiques homologues, et une plus faible activité biologique dans un test réalisé sur des préadipocytes 3T3-F442A; cela en dépit du fait que les deux hormones présentent des réactions croisées presque identiques avec un anticorps anti-cGH polyclonale. Ces résultats, associés à une comparaison à la structure de l'hGH, suggèrent que le Cys-123 est localisé dans la partie hydrophobique de l'hormone, et affecte, le plus vraisemblablement, la conformation du site de liaison. Les formes dimériques de l'hormone et de sa forme mutée sont moins actives que leurs monomères respectifs. Les études de liaison homologue, réalisées avec des fractions microsomales de foie, révèlent une population unique de récepteurs de Kd = 0,77 nM et de Bmax = 241 fmol/mg de proteine microsomale.相似文献
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Urban habitats, particularly wastelands and brownfields, maintain rich biodiversity and offer habitat for many species, even rare and endangered taxa. However, such habitats are also under socio-economic pressures due to redevelopment for housing and industrial uses. In order to maintain urban biodiversity, it is currently unknown how much open area must be preserved and whether conservation is possible without complete exclusion from economic development. In this study, we applied a simulation model based on species distribution models for plants, grasshoppers, and leafhoppers to investigate planning options for urban conservation with special focus on business areas. Altogether, we modelled the occurrence of 81 species of the urban species pool and analysed settings of different proportions of open sites, different habitat turnover times, and different lot sizes. Our simulations demonstrated that dynamic land use supports urban biodiversity in terms of species richness and rarity. Setting aside brownfields before redevelopment for a period of on average 15 years supported the highest conservation value. Consequently, we recommend integrating the concept of ‘temporary conservation’ into urban planning for industrial and business areas. This concept requires habitat to be destroyed by redeveloping brownfield sites to built-up sites, but simultaneously creating new open spaces due to abandonment of urban land uses at other locations. This maintains a spatio-temporal mosaic of different successional stages ranging from pioneer to pre-forest communities. 相似文献
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Jun M Shao Y Ho CT Koetter U Lech S 《Journal of agricultural and food chemistry》2003,51(21):6340-6346
The degradation profile of glucosamine bulk form stressed at 100 degrees C for 2 h in an aqueous solution was studied. Column chromatography of acetylated product mixture led to isolation of two pure compounds (1b and 2b) and a mixture of at least three isomers (3b). 1a and 2a were identified as 5-(hydroxymethyl)-2-furaldehyde (5-HMF) and 2-(tetrahydroxybutyl)-5-(3',4'-dihydroxy-1'-trans-butenyl)pyrazine, respectively, by utilizing a variety of analytical techniques, such as GC-MS, LC-MS, on-line UV spectrum, (1)H and (13)C NMR, and DEPT, as well as (1)H-(1)H COSY. 3a was identified as 2-(tetrahydroxybutyl)-5-(2',3',4'-trihydroxybutyl)pyrazine, commonly known as deoxyfructosazine. In addition, glucosamine solid dosage form was exposed to 40 degrees C/75% relative humility for 10 weeks. Methanol extract of glucosamine solid dosage form was analyzed after acetylation by LC-MS, resulting in degradants 3b and 4b. 3a and 4a were, therefore, determined as deoxyfructosazine and 2,5-bis(tetrahydroxybutyl)pyrazine (fructosazine), respectively. Furthermore, the mechanisms of formation of identified degradation products are proposed and briefly discussed. 相似文献
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Aviram M Volkova N Coleman R Dreher M Reddy MK Ferreira D Rosenblat M 《Journal of agricultural and food chemistry》2008,56(3):1148-1157
We have analyzed in vivo and in vitro the antiatherogenic properties and mechanisms of action of all pomegranate fruit parts: peels (POMxl, POMxp), arils (POMa), seeds (POMo), and flowers (POMf), in comparison to whole fruit juice (PJ). Atherosclerotic E 0 mice consumed POM extracts [200 microg of gallic acid equivalents (GAE)/mouse/day] for 3 months. Blood samples, peritoneal macrophages (MPM), and aortas were then collected. All POM extracts possess antioxidative properties in vitro. After consumption of PJ, POMxl, POMxp, POMa, or POMf by E (0) mice, the atherosclerotic lesion area was significantly decreased by 44, 38, 39, 6, or 70%, respectively, as compared to placebo-treated group, while POMo had no effect. POMf consumption reduced serum lipids, and glucose levels by 18-25%. PJ, POMxl, POMxp, POMf, or POMa consumption resulted in a significant decrement, by 53, 42, 35, 27, or 13%, respectively, in MPM total peroxides content, and increased cellular paraoxonase 2 (PON2) activity, as compared to placebo-treated mice. The uptake rates of oxidized-LDL by E (0)-MPM were significantly reduced by approximately 15% after consumption of PJ, POMxl, or POMxp. Similar results were obtained on using J774A.1 macrophage cell line. Finally, pomegranate phenolics (punicalagin, punicalin, gallic acid, and ellagic acid), as well as pomegranate unique complexed sugars, could mimic the antiatherogenic effects of pomegranate extracts. We conclude that attenuation of atherosclerosis development by some of the POM extracts and, in particular, POMf, could be related to the combined beneficial effects on serum lipids levels and on macrophage atherogenic properties. 相似文献
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José M. Herrera Isa de Sá Teixeira Javier Rodríguez-Pérez António Mira 《Landscape Ecology》2016,31(4):731-743