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921.
Biao Gong Dan Wen Sean Bloszies Xiu Li Min Wei Fengjuan Yang Qinghua Shi Xiufeng Wang 《Acta Physiologiae Plantarum》2014,36(8):2167-2181
Physiological responses of tomato roots to NaCl and NaHCO3 stresses were investigated in a hydroponic setting. The relative growth rate of tomato plants was significantly reduced in both NaCl and NaHCO3 treatments, especially under NaHCO3 stress. Tomato root respiration increased under low concentrations of NaCl and NaHCO3 stresses. However, high concentrations of both NaCl and NaHCO3 significantly inhibited respiration, especially in the NaHCO3 treatment. With increasing concentration of NaCl and NaHCO3 treatment, root Na accumulation increased, while accumulation of N, P, K, Fe, and Mg was significantly lower. Compared to NaCl, NaHCO3 treatment resulted in more dramatic changes in these nutrients. All organic acids investigated were increased by NaHCO3 after 5 days of treatment, but only oxalate, tartrate and malate were induced by NaCl. This implies that global regulation of organic acids might play an important role in tomato’s alkali stress tolerance. Compared to NaCl treatments, NaHCO3 treatments induced much higher levels of reactive oxygen species (ROS) and lipid peroxidation after 5 days of treatment, which was accompanied by higher activities of antioxidant enzymes and higher concentrations of ascorbate–glutathione. However, after 10 days of treatment, 100 mM NaHCO3 stress led to lower accumulation of ROS, antioxidant enzyme activities, and ascorbate–glutathione content. This may have been because root metabolism had almost completely stopped, as indicated by lower root respiration and activity. 相似文献
922.
R. J. Gruninger X. Gong R. J. Forster T. A. McAllister 《Applied microbiology and biotechnology》2014,98(7):3003-3012
Functional screening of a metagenomic library constructed with DNA extracted from the rumen contents of a grass/hay-fed dairy cow identified a protein, β-glucosidase/β-xylosidase/α-arabinosidase gene (Bgxa1), with high levels of β-glucosidase activity. Purified Bgxa1 was highly active against p-nitrophenyl-β-d-glucopyranoside (pNPG), cellobiose, p-nitrophenyl-β-d-xylopyranoside (pNPX) and p-nitrophenyl-α-d-arabinofuranoside (pNPAf), suggesting it is a multifunctional β-glucosidase/β-xylosidase/α-arabinosidase. Kinetic analysis of the protein indicated that Bgxa1 has the greatest catalytic activity against pNPG followed by pNPAf and pNPX, respectively. The catalytic efficiency of β-glucosidase activity was 100× greater than β-xylosidase or α-arabinosidase. The pH and temperature optima for the hydrolysis of selected substrates also differed considerably with optima of pH 6.0/45 °C and pH 8.5/40 °C for pNPG and pNPX, respectively. The pH dependence of pNPAf hydrolysis displayed a bimodal distribution with maxima at both pH 6.5 and pH 8.5. The enzyme exhibited substrate-dependent responses to changes in ionic strength. Bgxa1 was highly stable over a broad pH range retaining at least 70 % of its relative catalytic activity from pH 5.0–10.0 with pNPG as a substrate. Homology modelling was employed to probe the structural basis of the unique specificity of Bgxa1 and revealed the deletion of the PA14 domain and insertions in loops adjacent to the active site. This domain has been found to be an important determinant in the substrate specificity of proteins related to Bgxa1. It is postulated that these indels are, in part, responsible for the multifunctional activity of Bgxa1. Bgxa1 acted synergistically with endoxylanase (Xyn10N18) when incubated with birchwood xylan, increasing the release of reducing sugars by 168 % as compared to Xyn10N18 alone. Examination of Bgxa1 and Xyn10N18 synergy with a cellulase for the saccharification of alkali-treated straw revealed that synergism among the three enzymes enhanced sugar release by 180 % as compared to cellulase alone. Our results suggest that Bgxa1 has a number of properties that make it an interesting candidate for the saccharification of lignocellulosic material. 相似文献
923.
924.
925.
Fengchang Qiao Kun Zhang Pihai Gong Ling Wang Jiaojiao Hu Sen Lu Hong Fan 《Molecular biology reports》2014,41(9):5693-5700
miRNAs have emerged as crucial regulators in the regulation of development as well as human diseases, especially tumorigenesis. The aims of this study are to evaluate miR-30b-5p expression pattern and mechanism in gastric carcinogenesis due to which remains to be determined. Expression of miR-30b-5p was analyzed in 51 gastric cancer cases and 4 cell lines by qRT-PCR. The effect of DNA methylation on miR-30b-5p expression was assessed by MSP and BGS. In order to know whether DNMT1 increased miR-30b-5p promoter methylation, DNMT1 was depleted in cell lines AGS and BGC-823. The role of miR-30b-5p on cell migration was evaluated by wound healing assays. Decreased expression of miR-30b-5p was found in gastric cancer samples. In tumor, the expression level of miR-30b-5p was profound correlated with lymph node metastasis (P = 0.019). The level of miR-30b-5p may be restored by DNA demethylation and DNMT1 induced miR-30b-5p promoter methylation. In vitro functional assays implied that enforced miR-30b-5p expression affected cell migration, consistent with tissues analysis. Our findings uncovered that miR-30b-5p is significantly diminished in gastric cancer tissues, providing the first insight into the epigenetic mechanism of miR-30b-5p down-regulation, induced by DNMT1, and the role of miR-30b-5p in gastric cancer carcinogenesis. Overexpression of miR-30b-5p inhibited cell migration. Thus, miR-30b-5p may represent a potential therapeutic target for gastric cancer therapy. 相似文献
926.
927.
Jianxue Gong Shujuan Gong Min Zhang Lianwei Zhang Yuyan Hu Yixian Liu Wenbin Li 《Amino acids》2014,46(6):1537-1545
Our previous study has shown that cerebral ischemic preconditioning (CIP) can up-regulate the expression of glial glutamate transporter-1 (GLT-1) during the induction of brain ischemic tolerance in rats. The present study was undertaken to further explore the uptake activity of GLT-1 in the process by observing the changes in the concentration of extracellular glutamate with cerebral microdialysis and high-performance liquid chromatography. The results showed that a significant pulse of glutamate concentration reached the peak value of sevenfold of the basal level after lethal ischemic insult, which was associated with delayed neuronal death in the CA1 hippocampus. When the rats were pretreated 2 days before the lethal ischemic insult with CIP which protected the pyramidal neurons against delayed neuronal death, the peak value of glutamate concentration decreased to 3.9 fold of the basal level. Furthermore, pre-administration of dihydrokainate, an inhibitor of GLT-1, prevented the protective effect of CIP on ischemia-induced CA1 cell death. At the same time, compared with the CIP + Ischemia group, the peak value of glutamate concentration significantly increased and reached sixfold of the basal level. These results indicate that CIP induced brain ischemic tolerance via up-regulating GLT-1 uptake activity for glutamate and then decreasing the excitotoxicity of glutamate. 相似文献
928.
929.
Xionghui Zhong Xue Yuan Ze Wu Muhammad Ali Khan Jin Chen Xiaoxin Li Benhe Gong Yang Zhao Jian Wu Chenyu Wu Mingfang Yi 《Plant cell reports》2014,33(2):301-312
Key message
Virus-induced gene silencing (VIGS) system could be performed successfully in Gladiolus hybridus with vacuum infiltration of cormels and young plants.Abstract
Functional analysis of genes in gladiolus has previously been impractical due to the lack of an efficient stable genetic transformation method. However, virus-induced gene silencing (VIGS) is effective in some plants which are difficult to transform through other methods. Although the Tobacco rattle virus (TRV)-based VIGS system has been developed and used for verifying gene functions in diverse plants, an appropriate TRV-VIGS approach for gladiolus has not been established yet. In this report we describe the first use of the TRV-VIGS system for gene silencing in gladiolus. Vacuum infiltration of cormels and young plants with the GhPDS-VIGS vector effectively down-regulated the PHYTOENE DESATURASE ortholog GhPDS gene and also resulted in various degrees of photobleaching in Gladiolus hybridus. The reduction in GhPDS expression was tested after TRV-based vector infection using real-time RT-PCR. In addition, the progress of TRV infection was detected by fluorescence visualization using a pTRV2: CP-GFP vector. In conclusion, the TRV-mediated VIGS described here will be an effective gene function analysis mechanism in gladiolus. 相似文献930.
Insulin‐Like Growth Factor Binding Protein 4 Enhances Cardiomyocytes Induction in Murine‐Induced Pluripotent Stem Cells 下载免费PDF全文