Molecular characterisation of quinolone resistance in Escherichia coli from animals in Turkey

The aim of this study were to detect the gyrA, parC and marR mutations and qnr genes (qnrA, qnrB and qnrS) in 120 strains of Escherichia coli isolated from animals. European Committee on Antimicrobial Susceptibility Testing and Clinical Laboratory Standards Institute disc diffusion and minimum inhibitory concentration (MIC) tests, respectively, were used to determine fluoroquinolone (FQ) resistance, and molecular methods were used to detect the mutations and the genes. E coli isolates with an MIC of ≥8 mg/l had mutation at Ser-80 in parC in addition to mutations at Ser-83, Asp-87 or both in gyrA. The nucleotide change was detected in marR (Ser-3?→?Asn, Ala-53?→?Glu, Gly-103?→?Ser, Tyr-137?→?His). Only four E coli isolates (3.3 per cent) contained qnrA and qnrS, and qnrB was not detected. Two E coli isolates from healthy calves also contained qnrA and qnrS. The MICs of enrofloxacin and danofloxacin for qnr-containing E coli isolates ranged from 32 mg/l to 256 mg/l. The results of this study indicated that the FQ-resistant E coli isolates presented an alteration in gyrA (Ser-83?→?Leu, Asp-87?→?Asn) and parC (Ser-80?→?Ile) with high MICs (8-256 mg/l), and there was a low prevalence of qnr genes among E coli isolated from animals.     

Nitric oxide improves high zinc tolerance in maize plants

A short-term experiment was carried out to study the effects of exogenous nitric oxide (NO) on some growth parameters and mineral nutrients of maize grown at high zinc (Zn). Maize seedlings were planted in pots containing perlite and subjected to 0.05 or 0.5 mM Zn in nutrient solution. Nitric oxide (0.1 mM) was sprayed to the leaves of maize seedlings. High Zn reduced total dry matter, chlorophyll (Chl.) content and leaf relative water content (RWC), but increased proline content and membrane permeability. Foliar application of NO significantly increased chlorophyll content, RWC and growth of plants treated with high Zn, and significantly reduced their membrane permeability and proline contents. High Zn resulted in increased leaf and root Zn, but lower concentrations of leaf phosphorus (P), and iron (Fe). Foliar application of NO lowered leaf and root Zn and increased leaf and root nitrogen (N) and leaf Fe in the high Zn plants. These results clearly demonstrated that externally-applied NO induced growth improvement in maize plants was found to be associated with reduced membrane permeability under high zinc. Results can be concluded that NO may be involved in nutritional and physiological changes in plants subjected to high Zn.