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351.
Prakash NS Prasad V Chidambram TP Cherian S Jayaprakash TL Dasgupta S Wang Q Mann MT Spencer TM Boddupalli RS 《Transgenic research》2008,17(4):695-704
Identification of an appropriate selection agent and its corresponding selectable marker gene is one of the first steps in establishing a transformation protocol for a given plant species. As the promoter controls expression level of the genes, the promoter driving the selectable marker gene can affect transformation. However, investigations into the direct effect of promoters driving selectable marker on transformation are lacking in the literature though many reports of relative strengths of promoters driving reporter genes like GUS or CAT or GFP are available. In the present study, we have compared rice Actin1 and CaMV.35S (commonly used promoters in monocotyledonous plant transformation) promoters driving nptII for their effectiveness in paromomycin selection of transgenic corn events. To enable statistically meaningful analysis of the results, a large sample size of nearly 5,000 immature embryos (explants) was employed producing approximately 1,250 independent events from each of the two constructs in four independent experiments. The rate of appearance of resistant calli and percentage of resistant calli recovered was higher with P-Os.Actin1/nptII/nos3' as compared to P-CaMV.35S/nptII/nos3' in all four experiments. There was no appreciable difference either in the frequency of plant regeneration or in the morphological characteristics of plants recovered from the two constructs. Although the escape rate trended lower with P-Os.Actin1 as compared to P-CaMV.35S, the recovery of low copy events was significantly higher with P-CaMV.35S. The higher transformation frequency with P-Os.Actin1 could be related to the strength of this promoter as compared to P-CaMV.35S in the explants and/or calli. Based on these results, we infer that the promoter driving the selectable marker is an important factor to be considered while establishing a high throughput transformation protocol as it could not only influence the transformation frequency but also the copy number of the transgene in the recovered transgenics. 相似文献
352.
Shuxia Wang Sruti Shiva Maria H Poczatek Victor Darley-Usmar Joanne E Murphy-Ullrich 《The Journal of biological chemistry》2002,277(12):9880-9888
Excessive transforming growth factor-beta (TGF-beta) activity in hyperglycemia contributes to the development of diabetic nephropathy. Glucose stimulation of TGF-beta activity and matrix synthesis are dependent on autocrine thrombospondin 1 (TSP1) to convert latent TGF-beta to its biologically active form. The mechanisms by which glucose regulates TSP1 are not known. High glucose inhibits nitric oxide (NO) bioavailability and decreased NO increases TGF-beta activity and extracellular matrix accumulation. Yet, the impact of NO signaling on TSP1 activation of TGF-beta is unknown. We tested the role of NO signaling in the regulation of TSP1 expression and TSP1-dependent TGF-beta activity in rat mesangial cells exposed to high glucose. On exposure to 30 mm glucose, NO accumulation in the conditioned media and intracellular cGMP levels were significantly decreased. The addition of an NO donor prevented the glucose-dependent increase in TSP1 mRNA, protein, and TGF-beta bioactivity. The effects of the NO donor were blocked by ODQ (a soluble guanylate cyclase inhibitor) or Rp-8-pCPT-cGMPS (an inhibitor of cGMP-dependent protein kinase). These effects of high glucose were also reversed by the nitric-oxide synthase cofactor tetrahyrobiopterin (BH(4)). These results show that high glucose mediates increases in TSP1 expression and TSP1-dependent TGF-beta bioactivity through down-modulation of NO-cGMP-dependent protein kinase signaling. 相似文献
353.
Strains of mice that differ in voluntary alcohol consumption (VAC) are valuable models for the identification of genes involved in the complex etiology of alcohol effects and alcoholism. These mice offer a novel approach to the identification of strain-specific ethanol responsive (SSER) genes in tissues directly involved in alcohol metabolism and preference. We assessed mRNA from the liver and brain from male mice representing C57BL/6J, BALB/c, A/J, and DBA/2J strains following ethanol treatment (chronic ethanol fed liquid diet for 14 days or acute i.p. injection at two doses; 4 g/kg or 8 g/kg), using an expression array containing 588 genes (Clontech #7741-1). The results have identified NADPH cytochrome P450 oxidoreductase, insulin-like growth factor binding protein-1, glutathione S-transferase Mu 1, and cathepsin L as ethanol responsive genes in the liver. Further, we have established that IkB-alpha and clusterin genes in the brain are ethanol responsive, but only at the lower dose of the ethanol challenge. Although a number of other genes showing subtle (<2X) differences across strains and treatment combinations were reproducible in repeated blots, they were not confirmed by still evolving independent technologies of gene specific mRNA quantitation. The results demonstrate that comparative expression studies are an efficient approach to discover interacting gene networks that underlie the etiology of complex phenotypes including response to alcohols. 相似文献
354.
Mitochondria: regulators of signal transduction by reactive oxygen and nitrogen species 总被引:13,自引:0,他引:13
Brookes PS Levonen AL Shiva S Sarti P Darley-Usmar VM 《Free radical biology & medicine》2002,33(6):755-764
The functional role of mitochondria in cell physiology has previously centered around metabolism, with oxidative phosphorylation playing a pivotal role. Recently, however, this perspective has changed significantly with the realization that mitochondria are active participants in signal transduction pathways, not simply the passive recipients of injunctions from the rest of the cell. In this review the emerging role of the mitochondrion in cell signaling is discussed in the context of cytochrome c release, hydrogen peroxide formation from the respiratory chain, and the nitric oxide-cytochrome c oxidase signaling pathway. 相似文献
355.
During insulin-dependent diabetes mellitus, immune cells infiltrate pancreatic islets progressively and mediate beta cell destruction over a prolonged asymptomatic prediabetic period. Apoptosis may be a major mechanism of beta cell loss during the disease. This process involves a proteolytic cascade in which upstream procaspases are activated which themselves activate downstream caspases, including caspase-3, a key enzyme involved in the terminal apoptotic cascade. Here dual-label immunohistochemistry was employed to examine the intra-islet expression, distribution and cellular sources of active caspase-3 in the non-obese diabetic (NOD) mouse given cyclophosphamide to accelerate diabetes. NOD mice were treated at day 95 and caspase-3 expression was studied at days 0, 4, 7, 11 and 14. Its expression was also correlated with advancing disease and compared with age-matched NOD mice treated with diluent alone. At day 0 (=day 95), caspase-3 immunolabelling was observed in several peri-islet and intra-islet macrophages, but not in CD4 and CD8 cells and only extremely rarely in beta cells. At day 4, only a few beta cells weakly expressed the enzyme, in the absence of significant insulitis. At day 7, caspase-3 expression was observed in a small proportion of intra-islet macrophages. At day 11, there was a marked increase in the number of intra-islet macrophages positive for caspase-3 while only a few CD4 cells expressed the enzyme. At day 14, caspase-3 labelling became prominent in a significant proportion of macrophages. Only a few CD4 and CD8 cells expressed the enzyme. Capase-3 labelling was also present in a proportion of macrophages in perivascular and exocrine regions. Surprisingly, beta cell labelling of caspase-3 at days 11 and 14 was rare. At this stage of heightened beta cell loss, a proportion of intra-islet interleukin-1-positive cells coexpressed the enzyme. Caspase-3 was also observed in numerous Fas-positive cells in heavily infiltrated islets. During this late stage, only a proportion of caspase-3-positive cells contained apoptotic nuclei, as judged by terminal deoxynucleotidyl transferase-mediated dUTP nick-end labelling (TUNEL). We conclude that during cyclophosphamide-accelerated diabetes in the NOD mouse, the predominant immunolabelling of caspase-3 in intra-islet macrophages suggests that apoptosis of macrophages may be an important mechanism for its elimination. The virtual absence of caspase-3 immunolabelling in most beta cells even during heightened beta cell loss supports their rapid clearance following their death during insulin-dependent diabetes mellitus. 相似文献
356.
357.
Haghighat Khajavi S Kimura Y Oomori T Matsuno R Adachi S 《Bioscience, biotechnology, and biochemistry》2004,68(1):91-95
The decomposition process of maltose in subcritical water was studied using a tubular reactor in the temperature range of 180 to 260 degrees C and at 10 MPa. The formation of glucose and 5-hydroxymethyl-2-furaldehyde during the maltose decomposition was also observed. The decomposition rate of maltose was faster at higher temperatures. The rate was approximated by first-order kinetics during the early stage of the decomposition, but was accelerated and deviated from these kinetics at the later stage. The effluent pH decreased as the residence time in the reactor increased and the decrease of pH affected the maltose decomposition rate and glucose formation. Low pH of a feed solution accelerated maltose decomposition. A good correlation was obtained between the pH of the effluent and the rate constant of the first-order kinetics. 相似文献
358.
Kamal A Srinivas O Ramulu P Ramesh G Kumar PP Kumar MS 《Bioorganic & medicinal chemistry》2004,12(16):4337-4350
The synthesis of novel A-C8/C-C2-exo unsaturated alkoxyamido-linked pyrrolo[2,1-c][1,4]benzodiazepine dimers is reported and these dimers show significant DNA binding affinity and they also exhibit moderate anticancer activity. 相似文献
359.
360.
Minai-Tehrani D Ghaffari M Sobhani-Damavandifar Z Minoui S Alavi S Osmani R Ahmadi S 《Journal of enzyme inhibition and medicinal chemistry》2012,27(4):553-557
Ranitidine is an antagonist of histamine-2 (H(2)) receptor. It is employed to treat peptic ulcer and other conditions in which gastric acidity must be reduced. Sucrase is a hydrolytic enzyme that catalyzes the breakdown of sucrose to its monomer content. A liquid of yeast sucrase was developed for treatment of congenital sucrase-isomaltase deficiency (CSID) in human. In this study, the effect of ranitidine on yeast sucrase activity was investigated. Our results showed that ranitidine binds to sucrase and inhibits the enzyme in a noncompetitive manner. The K(i) and IC(50) values were measured to be about 2.3 and 2.2 mM, respectively. Fluorescence measurement showed conformational changes after binding of ranitidine to the enzyme. The fluorescence spectra showed that ranitidine could bind to both free enzyme and enzyme-substrate complex, which was accompanied with reduction of emission intensity and red shift production. 相似文献