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91.
Jung‐Sen Liu Tzu‐Hsuan Chiang Jinn‐Shyan Wang Li‐Ju Lin Wei‐Chih Chao Baskaran Stephen Inbaraj Jyh‐Feng Lu Bing‐Huei Chen 《Journal of cellular and molecular medicine》2015,19(7):1697-1709
The objectives of this study are to investigate antiproliferative effect and mechanisms of bioactive compounds from Gynostemma pentaphyllum (G. pentaphyllum) on lung carcinoma cell A549. Saponins, carotenoids and chlorophylls were extracted and fractionated by column chromatography, and were subjected to high‐performance liquid chromatography‐mass spectrometry analyses. The saponin fraction, which consisted mainly of gypenoside (Gyp) XXII and XXIII, rather than the carotenoid and chlorophyll ones, was effective in inhibiting A549 cell growth in a concentration‐ and a time‐dependent manner as evaluated using 3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyltetrazolium bromide (MTT) assay. The estimated half maximal inhibitory concentration (IC50) of Gyp on A549 cells was 30.6 μg/ml. Gyp was further demonstrated to induce an apparent arrest of the A549 cell cycle at both the S phase and the G2/M phase, accompanied by a concentration‐ and a time‐dependent increase in the proportions of both the early and late apoptotic cells. Furthermore, Gyp down‐regulated cellular expression of cyclin A and B as well as BCL‐2, while up‐regulated the expression of BAX, DNA degradation factor 35 KD, poly [ADP‐ribose] polymerase 1, p53, p21 and caspase‐3. Nevertheless, both the treatment of a p53 inhibitor, pifithrin‐α, and the small hairpin RNA‐mediated p53 knockdown in the A549 cells did not alter the growth inhibition effect induced by Gyp. As a result, the cell cycle arrest and apoptosis of A549 cells induced by Gyp would most likely proceed through p53‐independent pathway(s). 相似文献
92.
Volatile sulphur compounds (VSCs) are important to the food industry due to their high potency and presence in many foods. This study assessed for the first time VSC production and pathways of L: -methionine catabolism in yeasts from the genus Williopsis with a view to understanding VSC formation and their potential flavour impact. Five strains of Williopsis saturnus (var. saturnus, var. subsufficiens, var. suavolens, var. sargentensis and var. mrakii) were screened for VSC production in a synthetic medium supplemented with L: -methionine. A diverse range of VSCs were produced including dimethyl disulphide, dimethyl trisulphide, 3-(methylthio)-1-propanal (methional), 3-(methylthio)-1-propanol (methionol), 3-(methylthio)-1-propene, 3-(methylthio)-1-propyl acetate, 3-(methylthio)-1-propanoic acid (methionic acid) and ethyl 3-(methylthio)-1-propanoate, though the production of these VSCs varied between yeast strains. W. saturnus var. saturnus NCYC22 was selected for further studies due to its relatively high VSC production. VSC production was characterised step-wise with yeast strain NCYC22 in coconut cream at different L: -methionine concentrations (0.00-0.20%) and under various inorganic sulphate (0.00-0.20%) and nitrogen (ammonia) supplementation (0.00-0.20%), respectively. Optimal VSC production was obtained with 0.1% of L: -methionine, while supplementation of sulphate had no significant effect. Nitrogen supplementation showed a dramatic inhibitory effect on VSC production. Based on the production of VSCs, the study suggests that the Ehrlich pathway of L: -methionine catabolism is operative in W. saturnus yeasts and can be manipulated by adjusting certain nutrient parameters to control VSC production. 相似文献
93.
Calcium deficiency increases Cd toxicity and Ca is required for heat-shock induced Cd tolerance in rice seedlings 总被引:1,自引:0,他引:1
While growing in the field, plants may encounter several different forms of abiotic stress simultaneously, rather than a single stress. In this study, we investigated the effects of calcium (Ca) deficiency on cadmium (Cd) toxicity in rice seedlings. Calcium deficiency alone decreased the length, fresh and dry weight, and the Ca concentration in shoots and roots. Also, the content of glutathione (GSH), the ratio of GSH/oxidized glutathione, and the activity of catalase were lower in Ca-deficient leaves compared to control leaves. Exogenous Cd caused a decrease in the contents of chlorophyll and protein, and induced oxidative stress. Based on these stress indicators, we found that Ca deficiency enhanced Cd toxicity in rice seedlings. Under exogenous Cd application, internal Cd concentrations were higher in Ca-deficient shoots and roots than in the respective controls. Moreover, we observed that Ca deficiency decreased heat-shock (HS) induced expression of HS protein genes Oshsp17.3, Oshsp17.7, and Oshsp18.0 in leaves thereby weakening the protection system and increasing Cd stress. In conclusion, Ca deficiency enhances Cd toxicity, and Ca may be required for HS response in rice seedlings. 相似文献
94.
Oligopeptide-mediated gene transfer into mouse corneal endothelial cells: expression,design optimization,uptake mechanism and nuclear localization 下载免费PDF全文
Gene transfer to the corneal endothelium has potential in preventing corneal transplant rejection. In this study, we transfected mouse corneal endothelial cells (MCEC) with a class of novel arginine-rich oligopeptides. The peptides featured a tri-block design and mediated reporter gene expression in MCEC more efficiently than the commercial polyethylenimine standard. The functionality of each block was demonstrated to critically influence the performance of the peptide. Results from confocal imaging and flow cytometry then showed that energy-dependent endocytosis was the dominant form of uptake and multiple pathways were involved. Additionally, uptake was strongly dependent on interactions with cell-surface heparan sulphate. Fluorescence resonance energy transfer studies revealed that the peptide/DNA entered cells as an associated complex and some will have dissociated by 8.5 h. Large-scale accumulation of uncondensed DNA within the nucleus can also be observed by 26 h. Finally, as a proof of biological relevance, we transfected MCEC with plasmids encoding for the functional indoleamine 2,3-dioxygenase (IDO) enzyme. We then demonstrated that the expressed IDO could catalyse the degradation of l-tryptophan, which in turn suppressed the growth of CD4+ T-cells in a proliferation assay. 相似文献
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Endopolyploidy was observed in the protocorms of diploid Phalaenopsis aphrodite subsp. formosana with ploidy doubling achieved by in vitro regeneration of excised protocorms, or protocorm-like bodies (PLBs). Thirty-four
per cent of the PLBs regenerated from the first cycle of sectioned protocorms were found to be polyploids with ploidy doubled
once or twice as determined by flow-cytometry. The frequency of ploidy doubling increased as the sectioning cycles increased
and was highest in diploid followed by the triploid and tetraploid. Regeneration of the endopolyploid cells in the tissue
of the protocorms or PLBs is proposed as the source of the development of ploidy doubled plantlets. The frequency of ploidy
doubling was similar in seven other Phalaenopsis species, although the rate of increase within cycles was genotype specific. In two species, a comparison of five parameters
between 5-month-old diploid and tetraploid potted plants showed only the stomata density differed significantly. The flowers
of the tetraploid plant were larger and heavier than those of the diploids. This ploidy doubling method is a simple and effective
means to produce large number of polyploid Phalaenopsis species plants as well as their hybrids. The method will be beneficial to orchid breeding programs especially for the interspecific
hybridization between varieties having different chromosome sizes and ploidy levels. 相似文献
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99.
Salicylic acid-mediated hydrogen peroxide accumulation and protection against Cd toxicity in rice leaves 总被引:1,自引:0,他引:1
The role of H2O2 in salicylic acid (SA)-induced protection of rice leaves against subsequent Cd toxicity was investigated. SA pretreatment resulted in an increase in the contents of endogenous SA, as judged by the expression of OsWRKY45 (a SA responsive gene), and H2O2 in rice leaves. Diphenyleneiodonium (DPI) and imidazole (IMD), inhibitors of NADPH oxidase, prevented SA-increased H2O2 production, suggesting that NADPH oxidase is a H2O2-generating enzyme in SA-pretreated rice leaves. DPI and IMD also inhibited SA-increased activities of superoxide dismutase (SOD), ascorbate peroixdase (APX), and glutathione reductase (GR) activities, but had no effect on SA-increased catalase (CAT) activity. Moreover, SA-induced protection against subsequent Cd toxicity could also be prevented by DPI and IMD. The inhibitory effect of DPI and IMD on SA-induced protection against subsequent Cd toxicity could be reversed by exogenous H2O2. All these results suggested that SA-induced protection against subsequent Cd toxicity is mediated through H2O2. This conclusion is supported further by the observations that exogenous H2O2 application resulted in an increase in SOD, APX, and GR activities, but not CAT activity and a protection against subsequent Cd toxicity of rice leaves. 相似文献
100.