Chao Xu's research while affiliated with Huazhong Agricultural University and other places

Multidrug efflux pumps function at the frontline to protect bacteria against antimicrobials by decreasing the intracellular concentration of drugs. This protective barrier consists of a series of transporter proteins, which are located in the bacterial cell membrane and periplasm and remove diverse extraneous substrates, including antimicrobials, organic solvents, toxic heavy metals, etc., from bacterial cells. This review systematically and comprehensively summarizes the functions of multiple efflux pumps families and discusses their potential applications. The biological functions of efflux pumps including their promotion of multidrug resistance, biofilm formation, quorum sensing, and survival and pathogenicity of bacteria are elucidated. The potential applications of efflux pump-related genes/proteins for the detection of antibiotic residues and antimicrobial resistance are also analyzed. Last but not least, efflux pump inhibitors, especially those of plant origin, are discussed.

Androgens efficiently promote skeletal muscle growth and protein synthesis but causes neurotoxicity, genotoxicity and carcinogenicity, which had been prohibited applying in livestock. In this study, a broad-spectrum monoclonal antibody (mAb)-based indirect competitive enzyme-linked immunosorbent assay (ic-ELISA) has been developed for rapidly screening of androgens in various animal tissues. Primarily, a group-specific mAb, 4D12, was produced and showed IC50 values for nortestosterone, methyltestosterone, testosterone and trenbolone of 2.2, 0.3, 1.6 and 4.4 μg L⁻¹, respectively. The limits of detection and limits of quantification of this method for 4 androgens in 11 kinds of animal edible tissues ranged from 37.2 to 697.8 ng L⁻¹ and 70.0 to 1524.0 ng L⁻¹, respectively. The recoveries of the 11 kinds of samples spiked with 4 androgens were in the range from 65.0% to 106.6%, with coefficients of variation below 16.9%. A good correlation (R² = 0.998) was shown between the ic-ELISA and HPLC-MS/MS results for beef.