N-(3-oxo-hexanoyl)-homoserine lactone has a critical contribution to the quorum-sensing-dependent regulation in phytopathogen Pseudomonas syringae pv. tabaci 11528.

The phytopathogen Pseudomonas syringae pv. tabaci 11528 (P. syringae 11528), causing wild-fire disease in soybean and tobacco plants, processes PsyI-PsyR quorum-sensing (QS) system, in which PsyI is the N-(3-oxo-hexanoyl)-homoserine lactone (3OC6-HSL) synthase.

Exogenous N-acyl-homoserine lactones enhance the expression of flagella of Pseudomonas syringae and activate defence responses in plants.

In order to cope with pathogens, plants have evolved sophisticated mechanisms to sense pathogenic attacks and to induce defence responses. The N-acyl-homoserine lactone (AHL)-mediated quorum sensing in bacteria regulates diverse physiological processes, including those involved in pathogenicity. In this work, we study the interactions between AHL-producing transgenic tobacco plants and Pseudomonas syringae pv.

Separation and determination of estrogen in the water environment by high performance liquid chromatography-fourier transform infrared spectroscopy.

The components for connecting high-performance liquid chromatography (HPLC) with Fourier-transform infrared spectroscopy (FTIR) were investigated to determine estrogen in the water environment, including heating for atomization, solvent removal, sample deposition, drive control, spectrum collection, chip swap, cleaning and drying. Results showed that when the atomization temperature was increased to 388 K, the interference of mobile phase components (methanol, H2O, acetonitrile, and NaH2PO4) were completely removed in the IR measurement of estrogen, with 0.999 of similarity between IR spectra obtained after separation and corresponding to the standard IR spectra.

In Vitro Method To Assess Soil Arsenic Metabolism by Human Gut Microbiota: Arsenic Speciation and Distribution.

Arsenic (As) speciation and distribution are two important factors in assessing human health risk from As-contaminated soil. In this study, we used the combination of physiologically based extraction test (PBET) and Simulator of Human Intestinal Microbial Ecosystem (SHIME) to determine soil As metabolism by human gut microbiota. The results showed that the percentage of soil arsenate [As(V)] transformation reached 22.

Ectomycorrhizal colonization and growth of the hybrid larch F₁ under elevated CO₂ and O₃.

We studied the colonization of ectomycorrhizal fungi and species abundance of a hybrid larch (F1) under elevated CO₂ and O₃. Two-year-old seedlings were planted in an Open-Top-Chamber system with treatments: Control (O3 < 6 nmol/mol), O₃ (60 nmol/mol), CO₂ (600 μmol/mol), and CO2 + O₃. After two growing seasons, ectomycorrhiza (ECM) colonization and root biomass increased under elevated CO₂.

Diversity and dynamics of the microbial community on decomposing wheat straw during mushroom compost production.

The development of communities of three important composting players including actinobacteria, fungi and clostridia was explored during the composting of wheat straw for mushroom production. The results revealed the presence of highly diversified actinobacteria and fungal communities during the composting process. The diversity of the fungal community, however, sharply decreased in the mature compost.

A protective role of heme-regulated eIF2α kinase in cadmium-induced toxicity in erythroid cells.

Although a number of studies have demonstrated that cadmium (Cd) can incur damage to mature red cells, the potential injuries of Cd to erythroid progenitor cells have not been investigated thus far. Heme-regulated eIF2α kinase (Hri) is essential for translational regulation and survival of erythroid precursors in the setting of iron deficiency. Hri has been demonstrated to activate Atf4 signaling in reducing oxidative stress and in promoting erythroid differentiation during stress erythropoiesis.

Sensitive immunoassay detection of multiple environmental chemicals on protein microarrays using DNA/dye conjugate as a fluorescent label.

Indirect competitive immunoassays were developed on protein microarrays for the sensitive and simultaneous detection of multiple environmental chemicals in one sample. In this assay, a DNA/SYTOX Orange conjugate was employed as an antibody label to increase the fluorescence signal and sensitivity of the immunoassays. Epoxy-modified glass slides were selected as the substrate for the production of 4 × 4 coating antigen microarrays.

Development of indirect competitive fluorescence immunoassay for 2,2',4,4'-tetrabromodiphenyl ether using DNA/dye conjugate as antibody multiple labels.

An indirect competitive fluorescence immunoassay using a DNA/dye conjugate as antibody multiple labels was developed on 96-well plates for the identification and quantification of 2,2',4,4'-tetrabromodiphenyl ether (BDE-47) in aqueous samples. A hapten, 2,4,2'-tribromodiphenyl ether-4'-aldehyde, was synthesized, and was conjugated to bovine serum albumin to form a coating antigen. Specific recognition of the antigen by anti-PBDE antiserum was confirmed by a surface plasmon resonance measurement.

Determination of PCBs in tetrachlorinated quinone using gas chromatography with electron capture detection.

A simple, sensitive method for determining polychlorinated biphenyl (PCB) congeners in industrial product 2,3,5,6-tetrachloro-1,4-benzoquinone with GC/ECD detection has been developed. The method based on liquid-liquid extraction from tetrachlorinated quinone dissolved in N,N-dimethylformamide was found to be efficient for the determination of the levels of the investigated pollutants. A series of extraction and purification steps were designed for the sample pretreatment.

Impacts of sewage irrigation on heavy metal distribution and contamination in Beijing, China.

A potential hazard to Beijing was revealed due to the accumulation trend of heavy metals in agricultural soils with sewage irrigation, which results in metal contamination and human exposure risk. Samples including soils and plants were collected to assess the impacts of sewage irrigation on the irrigated farming area of Beijing. Concentrations of the five elements Cd, Cr, Cu, Zn, and Pb were determined in samples to calculate the accumulation factor and to establish a basis for environmental protection and the suitability of sewage irrigation for particular land use in the urban-rural interaction area of Beijing.

Transfer of metals from soil to vegetables in an area near a smelter in Nanning, China.

A field survey was conducted to investigate the metal contamination in soils and vegetables, and to evaluate the possible health risks to local population through foodchain transfer near a smelter in Nanning, southern China. Contamination levels in soils and vegetables with cadmium (Cd), lead (Pb), zinc (Zn) and copper (Cu) were measured, and transfer factors (TF) from soils to vegetable plants and its health risk (risk index, RI) were calculated accordingly. Results showed that both soils and vegetables from villages 1 and 2 (V1 and V2, 1500 m and 500 m from the smelter) were heavily contaminated, compared to a village 50 km from the smelter.

[Mutagenic activity of organic pollutants extracted from waters in Guanting Reservoir and Yongding River].

Water samples collected from Guanting Reservoir and Yongding River in July 1999 were examined by Ames test to evaluate the mutagenic activity of organic pollutants. The samples have been concentrated by using XAD-2 resin filled columns. In the test with strain TA98, direct mutagenic effects (-S9) were observed in water extracted from Bridge No.

Persistent organic pollutants (POPs) in surface sediments of Donghu Lake, Wuhan, Hubei, China.

Surface sediment samples from five different sites were collected in Donghu Lake, Wuhan City, Hubei Province, China during November 2000. Over 180 organic chemicals were detected using GC-MS controlled by a Hewlett Packard Chemstation after soxhlet extraction. Derivatives of benzene, phthalate esters, PAHs, phenols, isophorone as priority pollutants or endocrine disruptors, respectively, were detected.

Catalytically assisted electrochemical oxidation of dye Acid Red B.

This study focused on the degradation of dye Acid Red B in a catalytic electrolysis system with a semiconductor suspended in the electric field. The study showed that the addition of titanium dioxide substantially enhances the degradation of dye and that a semiconductor catalyst can improve electrolysis efficiency. This catalytic system has great potential to be applied commercially with the development of the catalyst.

Characterization and evaluation of a novel exalting round-plate photocatalytic reactor.

A novel reactor, the exalting round-plate photocatalytic reactor (ERPPR), was designed and evaluated. Residence time and light intensity distributions were determined by stimulus-response experimentation and an irradiation meter, respectively. The effects of hydraulic loading of the round plate and aeration on the photocatalytic degradation of azo dye were investigated during different conditions.

Use of ion chromatography for the determination of heavy and transition metals in biochemical samples.

A novel, highly sensitive method for simultaneous separation and determination of Cu2+, Ni2+, Zn2+, Cd2+, Co2+, Mn2+ and Pb2+ in biochemical samples was developed and evaluated by ion chromatography. All of these metals were well separated on a bifunctional ion-exchange column by a concentration gradient of oxalic acid and sodium chloride eluents, coupled with spectrophotometric detection after post-column derivatization with 2-[(5-bromo-2-pyridyl)azo]-5-diethylaminophenol at 560 nm. The method detection limits (signal-to-noise 3:1) were at microg l(-1) levels.

[Recent advances in absolute analysis by graphite furnace atomic absorption spectrometry].

This paper summarizes recent advances in absolute analysis by graphite furnace atomic absorption spectrometry, including the developments of absolute analysis in atomic absorption spectrometry, the theoretical calculation of characteristic mass, the study of the stability of experimental characteristic mass and the applications of standardless analysis in various samples.