Detection of hydrogen sulphide using cataluminescence sensors based on alkaline-earth metal salts

Detection of hydrogen sulphide (H₂S) was conducted based on cataluminescence (CTL) sensors, using alkaline‐earth metal carbonates as catalysts. Optimal working conditions, analytical characteristics and the response properties of the sensor were investigated. CTL intensity examination showed that sensors fabricated with CaCO₃, SrCO₃ or BaCO₃ could be used to detect H₂S gas sensitively. The optimal sensing temperature was about 320 °C. Under the sensing conditions with temperature at ca. 320 °C and gas flow rate in the range 180–200 mL/min, the linear range of CTL intensity vs H₂S concentration was 25–500 ppm, with a detection limit of 2 ppm. The response and recovery times of the sensor were within 5 and 25 min, respectively. Also, the sensor had the property of high selectivity to H₂S with very weak or no obvious response to 14 other gases, such as NO₂, NH₃, hydrocarbons and alcohol. Copyright © 2011 John Wiley & Sons, Ltd.     

A Bacillus subtilis sensor kinase involved in triggering biofilm formation on the roots of tomato plants

The soil bacterium Bacillus subtilis is widely used in agriculture as a biocontrol agent able to protect plants from a variety of pathogens. Protection is thought to involve the formation of bacterial communities - biofilms - on the roots of the plants. Here we used confocal microscopy to visualize biofilms on the surface of the roots of tomato seedlings and demonstrated that biofilm formation requires genes governing the production of the extracellular matrix that holds cells together. We further show that biofilm formation was dependent on the sensor histidine kinase KinD and in particular on an extracellular CACHE domain implicated in small molecule sensing. Finally, we report that exudates of tomato roots strongly stimulated biofilm formation ex planta and that an abundant small molecule in the exudates, (L) -malic acid, was able to stimulate biofilm formation at high concentrations in a manner that depended on the KinD CACHE domain. We propose that small signalling molecules released by the roots of tomato plants are directly or indirectly recognized by KinD, triggering biofilm formation.     

Critical role for CCAAT/enhancer-binding protein β in immune complex-induced acute lung injury

C/EBPs, particularly C/EBPβ and C/EBPδ, are known to participate in the regulation of many genes associated with inflammation. However, very little is known regarding the activation and functions of C/EBPβ and C/EBPδ in acute lung inflammation and injury. In this study, we show that both C/EBPβ and C/EBPδ activation are triggered in lungs and in alveolar macrophages following intrapulmonary deposition of IgG immune complexes. We further show that mice carrying a targeted deletion of the C/EBPβ gene displayed significant attenuation of the permeability index (lung vascular leak of albumin), lung neutrophil accumulation (myeloperoxidase activity), total number of WBCs, and neutrophils in bronchoalveolar lavage fluids compared with wild-type mice. Moreover, the mutant mice expressed considerably less TNF-α, IL-6, and CXC/CC chemokine and soluble ICAM-1 proteins in bronchoalveolar lavage fluids, and corresponding mRNAs in the IgG immune complex-injured lung, compared with wild-type mice. These phenotypes were associated with a significant reduction in morphological lung injury. In contrast, C/EBPδ deficiency had no effect on IgG immune complex-induced lung injury. IgG immune complex-stimulated C/EBPβ-deficient alveolar macrophages released significantly less TNF-α, IL-6, MIP-2, keratinocyte cell-derived chemokine, and MIP-1α compared with wild-type cells. Similar decreases in IgG immune complex-induced inflammatory mediator production were observed following small interfering RNA ablation of C/EBPβ in a murine alveolar macrophage cell line. These findings implicate C/EBPβ as a critical regulator of IgG immune complex-induced inflammatory responses and injury in the lung.     

CircPRMT5 circular RNA promotes proliferation of colorectal cancer through sponging miR-377 to induce E2F3 expression

CircPRTM5 is associated with cell proliferation and migration in many kinds of malignancies. However, the functions and mechanisms of CircPRTM5 in CRC progression remain unclear. We explored the role and the mechanisms of CircPRTM5 in the development of CRC. Tissues of CRC patients and matched adjacent non-tumour tissues were collected to evaluate the expression of CircPRTM5. The expression of CircPRTM5 in CRC tissues was significantly higher than that in adjacent tissues. The biological functions of CircPRTM5 in CRC were determined by overexpression and down-regulation of CircPRTM5 in CRC cells in vitro and in vivo. The results indicate that knockdown of CircPRTM5 can significantly inhibit the proliferation of CRC cells. The potential mechanisms of CircPRTM5 in CRC development were identified by RT-qPCR, Western blotting analysis and luciferase reporter assay. CircPRTM5 competitively regulates the expression of E2F3 by capillary adsorption of miR-377. CircPRMT5 regulates CRC proliferation by regulating the expression of E2F3, which affects the expression of the cell cycle-associated proteins cyclinD1 and CDK2. CircPRTM5 exerts critical regulatory role in CRC progression by sponging miR-377 to induce E2F3 expression.     

植酸钠对黑曲霉柠檬酸发酵产酸的促进效应

研究了植酸钠对黑曲霉柠檬酸发酵产酸的促进效应。在葡萄糖全合成培养基中添加１％的植酸钠,可使产酸比对照提高２．４倍;在薯粉、玉米粉等天然培养基中添加１％植酸钠,柠檬酸产量分别提高１．７倍和１．３倍。酶活性测定分析表明,植酸钠对柠檬酸代谢途径中的几种关键酶的活性有影响。     

Cyclophilin A binds to AKT1 and facilitates the tumorigenicity of Epstein-Barr virus by mediating the activation of AKT/mTOR/NF-κB positive feedback loop

The AKT/mTOR and NF-κB signalings are crucial pathways activated in cancers including nasopharyngeal carcinoma (NPC), which is prevalent in southern China and closely related to Epstein-Barr virus (EBV) infection. How these master pathways are persistently activated in EBV-associated NPC remains to be investigated. Here we demonstrated that EBV-encoded latent membrane protein 1 (LMP1) promoted cyclophilin A (CYPA) expression through the activation of NF-κB. The depletion of CYPA suppressed cell proliferation and facilitated apoptosis. CYPA was able to bind to AKT1, thus activating AKT/mTOR/NF-κB signaling cascade. Moreover, the use of mTOR inhibitor, rapamycin, subverted the activation of the positive feedback loop, NF-κB/CYPA/AKT/mTOR. It is reasonable that LMP1 expression derived from initial viral infection is enough to assure the constant potentiation of AKT/mTOR and NF-κB signalings. This may partly explain the fact that EBV serves as a tumor-promoting factor with minimal expression of the viral oncoprotein LMP1 in malignancies. Our findings provide new insight into the understanding of causative role of EBV in tumorigenicity during latent infection.     

Complete genome sequence of an H10N8 avian influenza virus isolated from a live bird market in Southern China

An H10N8 avian influenza virus (AIV), designated A/Duck/Guangdong/E1/2012 (H10N8), was isolated from a duck in January 2012. This is first report that this subtype of AIV was isolated from a live bird market (LBM) in Guangdong Province in southern China. Furthermore, the complete genome of this strain was analyzed. The availability of genome sequences is helpful to further investigations of epidemiology and molecular characteristics of AIV in southern China.     

Surface display of ACC deaminase on endophytic <Emphasis Type="Italic">Enterobacteriaceae</Emphasis> strains to increase saline resistance of host rice sprouts by regulating plant ethylene synthesis

Background

Most endophytic bacteria in consortia, which provide robust and broad metabolic capacity, are attractive for applications in plant metabolic engineering. The aim of this study was to investigate the effects of engineered endophytic bacterial strains on rice sprout ethylene level and growth under saline stress. A protocol was developed to synthesize engineered strains by expressing bacterial 1-aminocyclopropane-1-carboxylate (ACC) deaminase gene on cells of endophytic Enterobacter sp. E5 and Kosakonia sp. S1 (denoted as E5P and S1P, respectively).

Results

Results showed that ACC deaminase activities of the engineered strains E5P and S1P were significantly higher than those of the wild strains E5 and S1. About 32–41% deaminase was expressed on the surface of the engineered strains. Compared with the controls without inoculation, inoculation with the wild and engineered strains increased the deaminase activities of sprouts. Inoculation with the engineered strains increased 15–21% more deaminase activities of sprouts than with the wild strains, and reduced the ethylene concentrations of sprouts more significantly than with wild strains (P < 0.05). Inoculation with the wild and engineered strains promoted the growth of sprouts, while the promoting effects were more profound with the engineered strains than with the wild strains. The engineered strains improved saline resistance of sprouts under salt concentrations from 10 to 25 g L^?1. The engineered strains promoted longer roots and shoots than the wild strains under the salt stresses, indicating that the ACC deaminases on the endophytic bacterial cells could result in plant-produced ACC degradation and inhibit plant ethylene formation.

Conclusions

The protocols of expressing enzymes on endophytic bacterial cells showed greater potentials than those of plant over-expressed enzymes to increase the efficiency of plant metabolic pathways.