[Effects of Cotton Stalk Biochar on the Structure and Function of Fungi Community in Alkaline Rhizosphere Soil of Rice Under Cadmium Pollution].

To study the effects of cotton stalk biochar on the regulation of fungal diversity, the structure and function of alkaline rice rhizosphere soil under cadmium pollution was investigated. An outdoor pot experiment was conducted by adding cotton stalk biochar (0%, 1%, and 5%) to an alkaline paddy soil with a cadmium concentration of 0.1 and 8 mg·kg-1. Taking rice rhizosphere soil as the research object, Illumina HiSeq sequencing was used to analyze the effects of cotton stalk biochar and cadmium pollution on the diversity, structure, abundance, and function of fungi in an alkaline rhizosphere soil, and to explore the correlation between soil environmental factors and the fungal community under the control of cotton stalk biochar. The results showed that:① the application of cotton stalk biochar significantly increased the soil pH, available nutrients, and organic matter, and reduced the content of reducible cadmium in the soil (P<0.05). ② The distribution of rice rhizosphere soil fungi was mainly Ascomycota, Aphelidiomycota, and Chytridiomycota, which accounted for 57% of all mycophytes. The genus was mainly Mortierella, Alternaria, and Fusarium. There was a significant difference in the α-diversity of the fungal community among the treatments (P<0.05). In the absence of cotton stalk biochar (C0), the increase in the cadmium concentration reduced the relative abundance and fungal diversity index (Shannon index) of Chytridiomycota, Mortierella, and Alternaria in the soil. Under different concentrations of cadmium (Cd0, Cd1, and Cd8), increasing cotton stalk biochar reduced the fungal community richness index (Chao1 index) and Shannon index. Cadmium pollution resulted in an increase in the relative abundance of Chytridiomycota in the soil, but decreased the abundance of Alternaria. The application of cotton stalk biochar could significantly increase the relative abundance of Chytridiomycota (P<0.05). Cadmium pollution reduced the abundance of Mortierella and Alternaria, but the application of cotton stalk biochar could increase the relative abundance of Alternaria. Increasing cotton stalk biochar means that soil will have more endophytes, plant pathogens, and saprophytes; while increasing cadmium pollution will reduce endophytes, plant pathogens, and saprophytes in the soil. ③ The main environmental factors affecting the diversity and structure of fungal communities are the available potassium, organic matter, and pH of the soil. The reducible cadmium content, which comprises the largest proportion of cadmium in rice soil, was significantly positively correlated to Rotifera, Aphelidiomycota, and Ascomycota (P<0.05), but negatively correlated to other mycophytes (P<0.05). The results indicate that cotton stalk biochar plays a certain role in the microecological regulation of alkaline cadmium-contaminated soil.

[Control of Cadmium Migration and Transformation in Alkaline Paddy Soil-Rice Using Cotton Stalk Biochar].

We investigated the effects of cotton stalk biochar addition on the soil nutrient characteristics of alkaline paddy soil and the migration and transformation of cadmium in a soil-rice system. An outdoor pot experiment was conducted with Tefengyou 2 rice as the testing material. We added cotton stalk biochar (0%, 1%, 2.5%, and 5%) in the alkaline paddy soil with cadmium content of 0, 1, 4, and 8 mg·kg-1. After rice harvesting, the effects of different concentrations of cotton stalk biochar on alkaline soil physical and chemical properties, cadmium enrichment and transfer in rice, and the occurrence of cadmium in soil were analyzed under different concentrations of cadmium stress. The results showed that ① adding cotton stalk biochar can effectively increase soil nutrient (P<0.05). After the addition of cotton stalk biochar, the organic matter increased by 25.74%-47.53%, and the available potassium content increased by 3.16-4.25 times. ② Cotton stalk carbon can reduce the cadmium content in soil and rice, especially after the application of 5% cotton stalk carbon, The cadmium content of brown rice at Cd4 and Cd8 concentrations decreased from 0.31 mg·kg-1 and 0.43 mg·kg-1 to 0.15 mg·kg-1 and 0.10 mg·kg-1, respectively, reaching the national standard. Cotton stalk biochar can significantly reduce the enrichment and transfer coefficient of cadmium in soil-rice systems and can increase the cadmium content in the residual cadmium but decrease the acid extractable cadmium, reducible cadmium, and oxidizable cadmium content (P<0.05). ③ Soil pH, conductivity, and nutrient indicators were significantly negatively correlated with cadmium content in rice and acid extractable cadmium, reducible cadmium, and oxidizable cadmium content in soil and were positively correlated with cadmium content in residual cadmium. The above results indicate that the application of cotton stalk biochar can significantly improve the soil nutrient of alkaline cadmium-contaminated paddy soil, and the application of cotton stalk biochar has a significant control effect on the migration and transformation of cadmium in alkaline soil and rice.

Effect of enterohaemorrhagic Escherichia coli O157:H7-specific enterohaemolysin on interleukin-1ß production differs between human and mouse macrophages due to the different sensitivity of NLRP3 activation.

Enterohaemorrhagic Escherichia coli (EHEC) O157:H7 infection in humans can cause acute haemorrhagic colitis and severe haemolytic uraemic syndrome. The role of enterohaemolysin (Ehx) in the pathogenesis of O157:H7-mediated disease in humans remains undefined. Recent studies have revealed the importance of the inflammatory response in O157:H7 pathogenesis in humans. We previously reported that Ehx markedly induced interleukin-1ß (IL-1ß) production in human macrophages. Here, we investigated the disparity in Ehx-induced IL-1ß production between human and mouse macrophages and explored the underlying mechanism regarding the activation of NOD-like receptor family, pyrin domain containing 3 (NLRP3) inflammasomes. In contrast to the effects on human differentiated THP-1 cells and peripheral blood mononuclear cells, Ehx exerted no effect on IL-1ß production in mouse macrophages and splenocytes because of a disparity in pro-IL-1ß cleavage into mature IL-1ß upon caspase-1 activation. Additionally, Ehx significantly contributed to O157:H7-induced ATP release from THP-1 cells, which was not detected in mouse macrophages. Confocal microscopy demonstrated that Ehx was a key inducer of cathepsin B release in THP-1 cells but not in mouse IC-21 cells upon O157:H7 challenge. Inhibitor experiments indicated that O157:H7-induced IL-1ß production was largely dependent upon caspase-1 activation and partially dependent upon ATP signalling and cathepsin B release, which were both involved in NLRP3 activation. Moreover, inhibition of K(+) efflux drastically diminished O157:H7-induced IL-1ß production and cytotoxicity. The findings in this study may shed light on whether and how the Ehx contributes to the development of haemolytic uraemic syndrome in human O157:H7 infection.

[Residues and health risk assessment of HCHs, DDTs and heavy metals in water and Tilapias from fish ponds of Guangdong].

Concentrations of copper, lead, cadmium, arsenic, hexachlorcyclohexane (HCHs) and dichlorodiphenyltrichloroethane (DDTs) in the water and the fish samples collected separately from fish pond, markets and supermarkets in four cities of Guangdong Province were measured by using GC-ECD, flame atomic absorption spectrometry and atomic fluorescence spectrometry. Health risk assessments associated with Cu, Pd, Cd, As, HCHs and DDTs were conducted based on the model of health risk assessment recommended by the US EPA. The results showed that the concentration ranges of Cu, Pd, Cd, As, HCHs and DDTs in water samples were nd-0.101 mg x L(-1), nd-0.097 mg x L(-1), nd-0.003 27 mg x L(-1), 0.0121-0.08127 mg x L(-1), 2.63-37.18 ng x L(-1) and 2.05-12.21 ng x L(-1), respectively. The health risk assessment indicates that the carcinogenic and non-carcinogenic risks of Cu, Pd, Cd, HCHs and DDTs in Tilapias both lower than the highest acceptable level of risk set by ICRP, but As cancer risk value slightly exceeded the upper limit of the acceptable risk levels in city population.

[Speciation analysis of Cd in PM10 and PM2.5 during heating period in Urumqi].

PM2.5 and PM10 samples were collected on campus of Xinjiang Agricultural University during Dec. 14-28, 2009, and the speciation of Cd in PM10 and PM2.5 and its health risk index was analyzed. The results showed that the pollution caused by PM10 and PM2.5 was severe here during the heating period; Cd in PM10 and PM2.5 was of concentration 3.642 and 1.964 ng x m(-3) respectively, mainly in the form of residue; however, Cd in PM2.5 had a higher bioavailability than that in PM10. The carcinogenic risk of Cd in PM10 and PM2.5 was 6.56 x 10(-6) and 3.46 x 10(-6) respectively, which were both acceptable.

[Prokaryotic expression and characterization of an antigenic gene of adult Trichinella spiralis].

OBJECTIVE: To obtain a purified Ts87 gene expression product of adult Trichinella spiralis and identify its immunogenicity. METHODS: Ts87 cDNA was subcloned into PET-28a(+) expression vector. The transformed bacteria bearing PET-28a(+)/Ts87 plasmids were induced by IPTG for production of fusion proteins. The expression product purified with His-binding affinity chromatography and electro-elution assay was analyzed by SDS-PAGE, ELISA and Western blot, and was used to immunize the rabbits. RESULTS: PET-28a(+)/Ts87 transformed bacteria produced the desired fusion protein with a relative molecular weight of 40 kDa. The antisera with high titer were obtained by immunizing rabbit with Ts87 recombinant protein. Ts87 expression protein was detected as positive reaction with infected rabbit sera, infected swine sera and antisera against Ts87 by ELISA. Ts87 protein was also recognized by above-mentioned sera with Western blotting. However, Ts87 protein failed to react with the patient sera infected with Cysticercus cellulosae or Echinococcus granulosus, and rabbit sera infected with Schistosoma japonicum. CONCLUSION: A new Trichinella recombinant protein with specific antigenicity was obtained.