Selenomethionine alleviates NF-κB-mediated inflammation in bovine mammary epithelial cells induced by Escherichia coli by enhancing autophagy.

Autophagy is crucial for the maintenance of homeostasis under stimuli related to infection. Selenium (Se) plays variable roles in defence against infection and Selenomethionine (Se-Met) is a common Se supplementation. This study aimed to understand whether Se-Met could regulate the nuclear factor-kappa B (NF-κB) signaling pathway through autophagy. Mammary alveolar cell-T (MAC-T) was challenged with Escherichia coli (E. coli). Western blotting and real-time quantitative PCR (RT-qPCR) were used to detect the protein expression and mRNA expression of cytokines. Immunofluorescence assays were performed to observe the expression of intracellular LC3. The results showed that E. coli inhibited autophagy by decreasing the LC3-Ⅱ protein levels, and the Atg5 and Beclin1 protein levels were increased after 4 h. Infection also decreased the number of LC3 puncta. E. coli increased the phosphorylation of p65 and IκBα protein. Concomitantly, the levels of interleukin (IL)-1ß, IL-6, IL-8 and tumour necrosis factor (TNF)-α mRNA increased at 3 and 4 h post-infection. We further explored the regulatory role of autophagy on NF-κB-mediated inflammation with autophagy modulators and shAtg5. The results indicated that the autophagy activator reduced the phosphorylation of p65 and IκBα and the mRNA expression of IL-1ß, IL-6, IL-8 and TNF-α. Additionally, activating autophagy weakened the adhesion to MAC-T of E. coli. Autophagy inhibitors exacerbated NF-κB-mediated inflammation and strengthened the adhesion of E. coli to cells. We then examined the effects of Se-Met on NF-κB-mediated inflammation through autophagy. The data suggested that Se-Met enhanced LC3-II expression, inhibited the E. coli-induced phosphorylation of p65 and IκBα, and suppressed the adhesion ability of E. coli to MAC-T and that the effects of Se-Met in attenuating NF-κB-mediated inflammation were partially blocked by an autophagy inhibitor. In summary, Se-Met alleviated NF-κB-mediated inflammation induced by E. coli by enhancing autophagy in bovine mammary epithelial cells.

Selectivity-tunable oxidation of tetrahydro-ß-carboline over an OMS-2 composite catalyst: preparation and catalytic performance.

Controlling the reaction selectivity of organic transformations without losing high conversion is always a challenge in catalytic processes. In this work, a H3PO4·12WO3/OMS-2 nanocomposite catalyst ([PW]-OMS-2) was prepared through the oxidation of a Mn(ii) salt with sodium phosphotungstate by KMnO4. Comprehensive characterization indicates that different Mn2+ precursors significantly affected the crystalline phase and morphology of the as-synthesized catalysts and only MnSO4·H2O as the precursor could lead to a cryptomelane phase. Moreover, [PW]-OMS-2 demonstrated excellent catalytic activity toward aerobic oxidative dehydrogenation of tetrahydro-ß-carbolines due to mixed crystalline phases, enhanced surface areas, rich surface oxygen vacancies and labile lattice oxygen species. In particular, ß-carbolines and 3,4-dihydro-ß-carbolines could be obtained from tetrahydro-ß-carbolines with very high selectivity (up to 99%) over [PW]-OMS-2 via tuning the reaction solvent and temperature. Under the present catalytic system, scalable synthesis of a ß-carboline was achieved and the composite catalyst showed good stability and recyclability. This work not only clarified the structure-activity relationship of the catalyst, but also provided a practical pathway to achieve flexible, controllable synthesis of functional N-heterocycles.

Characterization of Staphylococcus aureus Isolates From Cases of Clinical Bovine Mastitis on Large-Scale Chinese Dairy Farms.

Bovine mastitis is a prevalent disease that causes serious economic problems globally in the dairy industry. Staphylococcus aureus is an important pathogen of bovine mastitis. This study was conducted to characterize S. aureus isolates from clinical bovine mastitis cases in large-scale dairy herds in China. S. aureus was isolated from 624 clinical mastitis cases and confirmed by matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS). In total, 62 S. aureus isolates were obtained. Cluster analysis, genetic diversity, quantification of biofilm formation, antimicrobial resistance, and detection of virulence genes were performed on these isolates of S. aureus. Eight isolates harbored the mecA gene and were sensitive to oxacillin. MALDI-TOF MS cluster analysis revealed that the 62 isolates were divided into three major clusters (I, II, III) and eight main groups (A-H) at the distance level of 700. The agr II was the most prevalent (56.5%). The 62 S. aureus isolates were assigned to seven spa types. The most common spa type was t529(58.1%), followed by t2196 (14.5%), t518 (14.5%), t571(6.5%), t034 (3.2%), t2734 (1.6%), and t730 (1.6%). Five STs were identified from seven representative isolates as follows: ST630/CC8, ST97/CC97, ST50, ST398, and ST705. All isolates had the ability to form biofilm. Antimicrobial resistance was most frequently observed to ciprofloxacin (29%), followed by penicillin (24.2%), and streptomycin (9.6%). All isolates harbored the fnbA, clfB (100%), icaA, and icaD genes. This study provides the basis for the development of bovine mastitis prevention program on large-scale dairy farms.