Staphylococcus aureus (S. aureus) is the causative agent for a wide variety of illnesses ranging from minor skin infections to life-threatening diseases. Development of antibiotic resistance by the bacteria has rendered many antibiotics ineffective. It has been known that plectasin-derived antimicrobial peptides (AMPs; NZ2114 and MP1102) are promising alternatives to antibiotics. However, their activities against S. aureus in mammary glands were unknown. Our objective was to assess the antimicrobial activities of NZ2114 and MP1102 against S. aureus in milk, in cultured mammary epithelial cells, and in a mouse model in order to evaluate their potentials as anti-mastitis agents. NZ2114 and MP1102 showed in vitro bactericidal effects against S. aureus in both the culture medium and the milk. NZ2114 and MP1102 at the concentration of 100 μg/mL reduced the number of S. aureus by almost 100% within 4 h in processed bovine milk. Similarly, both NZ2114 and MP1102 were efficient to reduce the number of internalized S. aureus in cultured mammary epithelial cells. Finally, both AMPs significantly reduced the S. aureus load and concentrations of TNF-α and IL-6 in mammary glands, compared to a buffer control in the mouse model. Our results suggest that NZ2114 and MP1102 may be used to treat S. aureus-induced mastitis.

Photodissociation of jet-cooled, vibrationally excited CHF 2 Cl molecules was studied in a time-of-flight mass spectrometer to elucidate bond rupture and intramolecular dynamics. The molecules were first excited with infrared photons to the Nϭ3, Nϭ7/2, and Nϭ4 C-H stretch-bend polyad components, representing stretch-bend mixed states. They were then dissociated via promotion to excited electronic states by ϳ235 or 243.135 nm photons, which also tagged 35 Cl( 2 P j ) and 37 Cl( 2 P j ) or H photofragments, respectively, by ͑2ϩ1͒ resonantly enhanced multiphoton ionization. Comparison of the photofragment yield spectra to the simultaneously measured room-temperature infrared absorption spectra revealed significant narrowing of the former due to the reduction of rotational inhomogeneous structure. These spectra, and particularly the band contraction, afforded observation of resonance splitting in the vicinity of the 3 1 , 3 4 , 4 1 , and 4 4 components, reflecting redistribution times in the range of 1-18 ps. These times manifest the vibrational redistribution of the mixed states to other states of the molecule and are longer than those for the coupling of the stretch-bend. The initial vibrational excitation enhanced C-Cl and C-H bond cleavage with the former producing both ground-, Cl 2 P 3/2 ͓Cl͔, and excited-, Cl 2 P 1/2 ͓Cl*͔, spin-orbit states. The branching ratio of Cl*/Cl was ϳ0.5 and of H/͓Cl*ϩCl͔ϳ0.1, independent on the initially prepared state, signifying preferential production of Cl photofragments and energy flow from the initially excited bond.

β-elemene (β-ELE) is a natural compound extracted from that has shown promise as a novel anticancer drug to treat malignant tumors. Recent studies have demonstrated that β-ELE can reverse the drug resistance of tumor cells. To the best of our knowledge, there are no reports concerning the reversal of erlotinib resistance by β-ELE in human non-small cell lung cancer (NSCLC) cells. Therefore, the present study investigated the effects of β-ELE on erlotinib-resistant human NSCLC A549/ER cells and its possible mechanism of action. The sensitivity of A549/ER cells to erlotinib, the cytotoxicity of β-ELE on the growth of A549/ER cells and the effects of β-ELE on the reversal of drug resistance in A549/ER cells were determined by MTT assay. The cell apoptosis rate, cell cycle phase distribution and intracellular rhodamine 123 (Rh123) fluorescence intensity were detected by flow cytometry. The expression level of P-glycoprotein (P-gp) was detected by western blotting. A549/ER cells had a stable drug-resistance to erlotinib. β-ELE inhibited the proliferation of A549/ER cells in a time- and dose-dependent manner, enhanced the sensitivity of A549/ER cells to erlotinib and reversed the drug resistance in A549/ER cells. Treatment with 15 µg/ml β-ELE combined with 10 µmol/l erlotinib caused an increased rate of cell apoptosis and G/G phase arrest. Furthermore, β-ELE reduced the efflux of Rh123 from A549/ER cells, increased the intracellular accumulation of Rh123 and decreased the expression of P-gp. The results of the present study indicated that β-ELE could reverse drug resistance in erlotinib-resistant human NSCLC A549/ER cells through a mechanism that may involve the decreased expression of P-gp, inhibition of P-gp dependent drug efflux and the increased intracellular concentration of anticancer drugs.

Cattle are raised around the world and are frequently exposed to heat stress, whether in tropical countries or in regions with temperate climates. It is universally acknowledged that compared to those in temperate areas, the cattle breeds developed in tropical and subtropical areas have better heat tolerance. However, the underlying mechanism of heat tolerance has not been fully studied, especially from the perspective of intestinal microbiomics. The present study collected fecal samples of cattle from four representative climatic regions of China, namely, the mesotemperate (HLJ), warm temperate (SD), subtropical (HK), and tropical (SS) regions. Then, the feces were analyzed using high-throughput 16S rRNA sequencing. The results showed that with increasing climatic temperature from HLJ to SS, the abundance of Firmicutes increased, accompanied by an increasing Firmicutes to Bacteroidota ratio. Proteobacteria showed a trend of reduction from HLJ to SS. Patescibacteria, Chloroflexi, and Actinobacteriota were particularly highest in SS for adapting to the tropical environment. The microbial phenotype in the tropics was characterized by an increase in Gram-positive bacteria and a decrease in Gram-negative bacteria, aerobic bacteria, and the forming of_biofilms. Consistently, the functional abundances of organismal systems and metabolism were decreased to reduce the material and energy demands in a hot environment. Genetic information processing and information storage and processing may be how gut flora deals with hot conditions. The present study revealed the differences in the structure and function of gut microbes of cattle from mesotemperate to tropical climates and provided an important reference for future research on the mechanism of heat tolerance regulated by the gut microbiota and a potential microbiota-based target to alleviate heat stress.

Two-component systems (TCSs) are dominant regulating components in bacteria for responding to environmental stimuli. However, little information is available on how TCSs in Enterococcus faecium respond to bile salts – an important environmental stimulus for intestinal bacteria. In this study, the gene expression of 2 TCSs, BsrXRS and LiaFSR, was positively correlated with survival rates of different E. faecium isolates during exposure to ox gall. Moreover, gene disruptions of bsrR , bsrS , liaS , and liaR significantly reduced the survival rates of E. faecium in the presence of ox gall. Finally, EMSA results indicated that BsrR functioned as a transcription regulator for expression of its own gene as well as lipoate-protein ligase A ( lplA ). Additional 27 potential target genes by BsrR were revealed through in silico analyses. These findings suggest that BsrXRS and LiaFSR systems play important roles in bile salt resistance in E. faecium .