The nuclear receptor RXRα (retinoid X receptor-α) is a transcription factor that regulates the expression of multiple genes. Its non-genomic function is largely related to its structure, polymeric forms and modification. Previous research revealed that some non-genomic activity of RXRα occurs via formation of heterodimers with Nur77. RXRα–Nur77 heterodimers translocate from the nucleus to the mitochondria in response to certain apoptotic stimuli and this activity correlates with cell apoptosis. More recent studies revealed a significant role for truncated RXRα (tRXRα), which interacts with the p85α subunit of the PI3K/AKT signaling pathway, leading to enhanced activation of AKT and promoting cell growth in vitro and in animals. We recently reported on a series of NSAID sulindac analogs that can bind to tRXRα through a unique binding mechanism. We also identified one analog, K-80003, which can inhibit cancer cell growth by inducing tRXRα to form a tetramer, thus disrupting p85α–tRXRα interaction. This review analyzes the non-genomic effects of RXRα in normal and tumor cells, and discusses the functional differences based on RXRα protein structure (structure source: the RCSB Protein Data Bank).
Previous studies have indicated that homeodomain-leucine zipper (HD-Zip) transcription factors play important roles during abiotic stress, but there is no information on the functions of HD-Zip genes in a new model plant Eutrema salsugineum for studying plant abiotic stress tolerance. Here, EsHdzip1 (GenBank No. XM_006390503) belonging to the Class IV subgroup of HD-Zip transcription factor family was isolated from E. salsugineum and characterized for its physiological rolesunder drought stress conditions. Transgenic tobacco plants overexpressing EsHdzip1 exhibited increased drought resistance with promoted root growth and reduction of water loss. Furthermore, these transgenic plants had lower ion leakage (IL), malondialdehyde (MDA), and reactive oxygen species (ROS) accumulation, but higher content of osmotic solutes (proline and total soluble sugars) and activities of antioxidant enzymes including superoxide dismutase (SOD) and ascorbate peroxidase (APX) relative to wild-type (WT) plants when subjected to drought stress treatments. The content of abscisic acid (ABA) was also observed to be remarkably higher in the transgenic lines than WT plants under drought stress conditions. In addition, the expression levels of three important stress-related genes (NtP5CS, NtERD10C, and NtLEA5) involved in the osmotic adjustment and water maintenance were significantly higher than WT plants under drought stress conditions. Therefore, we have revealed important roles of the EsHdzip1 gene in response to drought stress, suggesting that this gene has a great potential for improving plant drought tolerance by engineering manipulation.
Impacts of dissolved oxygen (DO) and initial sludge concentrations on aerobic digestion for sewage sludge treatment were studied without adding alkalis. The MLVSS removal efficiencies were 50% and 47% in 20 days when DO concentrations were about 5.0 and 7.0 mg/L, respectively. Value of pH increased slightly in the first 6 days and then dropped constantly. The decrease of MLVSS appeared first quick back slow trend during the process and the OUR declination was similar. At the same DO level of 5.0 mg/L, the lower initial sludge concentration favored the efficiency of sludge stabilization. Both TN and TP of the supernatant were continually increasing and the ultimate concentrations were three to four times the initial concentrations. Results obtained from the present work could provide basic information for the aerobic sludge treatment process.
Starch and sodium carboxymethyl cellulose-coated Fe and Fe /Ni nanoparticles were synthesized and their Cr (VI) removal capabilities were evaluated and compared. We found that starch and sodium carboxymethyl cellulose-coated nanoscale zero-valent iron-nickel (SS-nZVI-Ni) showed the better Cr (VI) removal performance. The effect of acidic conditions on Cr(VI) removal by SS-Nzvi-Ni revealed that the Cr (VI) removal efficiency by SS-nZVI-Ni reached the maximum of 95.70% at pH = 2. The effect of different initial Cr (VI) concentrations showed that SS-nZVI-Ni performed well at a high Cr(VI) concentration. Langmuir-Hinshelwood first-order kinetic model could describe the reduction process well. SEM images revealed that SS-nZVI-Ni had a large surface area, which discarded the problem of aggregation. XRD and XPS analysis of SS-nZVI-Ni showed that SS-nZVI-Ni and Cr (III) formed an alloy on the surface of SS-nZVI-Ni after the reaction. The study provides an option for practical application of SS-nZVI-Ni in Cr (VI) removal.
Estimation of rice disease using spectral reflectance is important to non-destructive, rapid, and accurate monitoring of rice health. In this study, the rice reflectance data and disease index (DI) were determined experimentally and analyzed by single wave correlation, regression model and neural network model. The result showed that raw spectral reflectance and first derivative reflectance (FDR) difference of the rice necks under various disease severities is clear and obvious in the different spectral regions. There was also significantly negative or positive correlation between DI and raw spectral reflectance, FDR. The regression model was built with raw and first derivative spectral reflectance, which was correlated highly with the DI. However, due to rather complicated non-linear relations between spectral reflectance data and DI, the results of DI retrieved from the regression model was not so ideal. For this reason, an artificial neural network model (BP model) was constructed and applied in the retrieval of DI. For its superior ability for solving the nonlinear problem, the BP model provided better accuracy in retrieval of DI compared with the results from the statistic model. Therefore, it was implied that the rice neck blasts could be predicted by remote sensing technology.
Selenocysteine methyltransferase (SMT), specifically methylates selenocysteine (SeCys) to produce the nonprotein amino acid Se-methyl selenocysteine (SeMSC) and played key role of removing selenium toxic effect at higher levels to the plant. Here we report the cloning of a cDNA encoding selenocysteine methyltransferase from Camellia sinensis (CsSMT) and expression of CsSMT in E.coli. CsSMT isolated by RT-PCR and RACE-PCR reaction. CsSMT is a 1,401 bp cDNA with an open reading frame predicted to encode a 351 amino acid, 40.5 kD protein; The predicted amino acid sequences of CsSMT shows 74% identity with A. bisulcatus selenocysteine methyltransferase (AbSMT) and 69% identity with Broccoli (Brassica oleracea var. italica) selenocysteine methyltransferase (BoSMT), and shares 53, 73 and 65% identity, respectively, with Arabidopsis thaliana homocysteine S-methyltransferase AtHMT1, AtHMT2, and AtHMT3, and 65% to Zea mays homocysteine S-methyltransferase (ZmHMT2). Analyses of CsSMT showed that it lacks obvious chloroplast or mitochondrial targeting sequences and contains a consensus sequence of GGCC for a possible zinc-binding motif near the C-terminal and a conserved Cys residue upstream of the zinc-binding motif as other related methyltransferases. Expression of CsSMT correlated with the presence of SMT enzyme activity in cell extracts, and bacteria containing recombinant CsSMT plasmid showed much high tolerance to selenate and selenite.
Intensive anthropogenic disturbances have caused forest ecosystem degradation and soil erosion. Exotic fast-growing species are selected as pioneer species for restoration in degraded hilly lands of southern China. To better understand the potentials of the soil nematode trophic group composition in carbon sequestration, we investigated nematode trophic groups in Acacia, Eucalyptus, and Schima (native species as control) monoculture plantations in southern China after 23 years of reforestation. Our results showed that although total soil nematode abundance was not affected, the Acacia plantation significantly altered nematode trophic group composition over native species. Bacterivore and microbivore abundance, trophic diversity, and microbivore-driven soil organic carbon storage were higher in Acacia mangium than Schima superba. In contrast, plant parasitic nematode abundance and fungivore/bacterivore ratio were lower in Acacia mangium than Schima superba. As a result, Acacia mangium as a fast-growing pioneer tree species could be widely planted to maintain soil biodiversity and store carbon in restoring degraded forests in southern China. Eucalyptus exserta plantation enlarged the soil nematode community, including bacterivores, fungivores, and herbivores, suggesting that there is almost no allelopathy when eliminating anthropogenic disturbance in this study. Reasonable management is crucial for providing timber products and improving the ecological function of Eucalyptus plantations. Our results also highlight the critical roles of soil water and nutrient availability in regulating soil nematode trophic group composition and carbon sequestration.
High pathogenicity islands (HPIs) in Escherichia coli encode genes that are primarily involved in iron uptake and regulation, and confer virulence and pathogenicity. The aim of this study was to investigate the transfer of HPIs in avian E. coli and identify the function of HPI in the acceptor strain. The HPI transfer strain was obtained under conditions of low temperature and low iron abundance, and the donor and acceptor strains were confirmed. E. coli HPIs are transferred by horizontal gene transfer events, which are likely mediated primarily by homologous recombination in HPI-adjacent sequences. Assays for biological activity and pathogenicity changes in the acceptor strain indicated that HPIs might not be involved in pathogenesis in avian E. coli, and thus the main function of HPIs in this strain of bacteria may be to regulate iron nutrition.
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