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Chemosphere ; : 129008, 2020 Nov 21.
Artigo em Inglês | MEDLINE | ID: mdl-33261839


Due to human activity and global climate change, the Yellow River Delta, the youngest delta wetland in China, is suffering serious degradation. The study of hydrological connection provides new perspectives and technical support for the protection and restoration of delta wetlands. To quantify the interaction between the hydrological connection and the root-soil complex, the current study took dye-tracing experiments to examine the small-scale hydrological connectivity in soil where Phramites australis grew. The dye coverage was selected as the indicator of hydrological connectivity after preliminary analysis in this study. The main results were that (1) the strength of hydrological connectivity was negatively related to the microaggregates content, but had little to do with other soil physical properties; (2) there was a notable positive correlation between the indexes of thick root (D > 5 mm) and the dye coverage hydrological connectivity, while root biomass had little effect on hydrological connectivity; and (3) the influence of the microaggregate content dominated in the combined effect of the total surface area of the root (D > 5 mm) and the microaggregate content on hydrological connectivity in each soil layer.

Indian J Med Res ; 129(6): 701-6, 2009 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-19692753


BACKGROUND & OBJECTIVE: Fluoroquinolone has a broad spectrum of antimicrobial activity, and is widely used for gonorrhoea treatment. However, its efficacy can be compromised by the drug-resistance property of Neisseria gonorrhoeae isolates. Most resistant cases of N. gonorrhoeae are associated with mutations in the quinolone-resistance-determining-region (QRDR) within genes of gyrA and parC. This study was undertaken to describe resistance profile of N. gonorrhoeae to fluoroquinolones in Shanghai, P.R. of China, and also associated resistance mutations in gyrA and parC. METHODS: Eighty N. gonorrhoeae isolates were collected from Shanghai Skin Disease & Sexually Transmitted Disease Hospital or DongFang Hospital during April 2005 to April 2006 in Shanghai, P.R. of China. The minimum inhibitory concentrations (MIC) of fluoroquinolones for these isolates were determined by an agar dilution method. Mutation patterns within gyrA and parC were determined by direct sequencing or by using established restriction fragment length polymorphisms (RFLP) methods. RESULTS: Ninety five per cent (76 of 80) of isolates were resistant, 3.75 per cent (3 of 80) intermediate resistant, and 1.25 per cent (1 of 80) were sensitive to fluoroquinolone drug ciprofloxacin. Sequencing and RFLP analysis of gyrA and parC revealed that all resistant isolates had dual mutations of S91F and D95A/G/N in gyrA. Some isolates had an extra mutation within parC either of D86N, S87N or E91A/G. Mutation patterns for gyrA and parC were significantly (P<0.05) associated with MICs level. INTERPRETATION & CONCLUSION: Mutations of S91F and D95A/G/N in gyrA combined with S87N in parC was the most prevalent mutation pattern of fluoroquinolone resistant N. gonorrhoeae isolates. This mutation pattern was associated with a high level of quinolone resistance (MIC >16.0 microg/ml) which can serve as a maker for quinolone-resistance prediction in Shanghai, P.R. of China.

Antibacterianos , Farmacorresistência Bacteriana/genética , Fluoroquinolonas , Mutação , Neisseria gonorrhoeae , Antibacterianos/farmacologia , Antibacterianos/uso terapêutico , China , Fluoroquinolonas/farmacologia , Fluoroquinolonas/uso terapêutico , Humanos , Testes de Sensibilidade Microbiana , Neisseria gonorrhoeae/efeitos dos fármacos , Neisseria gonorrhoeae/genética , Polimorfismo de Fragmento de Restrição , Análise de Sequência de DNA