Salmonella typhimuriumcells were subjected to pulsed electric field (PEF) treatment at 25 kV/cm for 0–4 ms to investigate the effect of PEF on the cytoplasmic membrane lipids and oxidative injury of cells. Results indicated that PEF treatment induced a decrease of membrane fluidity ofSalmonella typhimurium(S. typhimuriumi), possibly due to the alterations of fatty acid biosynthesis-associated gene expressions (down-regulation ofcfaandfabAgene expressions and the up-regulation offabDgene expression), which, in turn, modified the composition of membrane lipid (decrease in the content ratio of unsaturated fatty acids to saturated fatty acids). In addition, oxidative injury induced by PEF treatment was associated with an increase in the content of malondialdehyde. The up-regulation of cytochrome bo oxidase gene expressions (cyoA,cyoB, andcyoC) indicated that membrane damage was induced by PEF treatment, which was related to the repairing mechanism of alleviating the oxidative injury caused by PEF treatment. Based on these results, we achieved better understanding of microbial injury induced by PEF, suggesting that micro-organisms tend to decrease membrane fluidity in response to PEF treatment and, thus, a greater membrane fluidity might improve the efficiency of PEF treatment to inactivate micro-organisms.Keywords:pulsed electric fields;Salmonella typhimurium;membrane lipids;cytoplasmic membrane fluidity;oxidative injury
Li Zong,Zifeng Pi,Shu Liu,Zhiqiang Liu,Fengrui Song
The comprehensive characterization of metabolome and lipidome to reveal unknown pathological conditions, are being used to investigate the molecular mechanisms of cancer, especially in the field of early diagnosis, treatment, and prognosis. The multidrug resistance (MDR) of tumor cells limits the therapeutic effect of anti-cancer drugs and is the main obstacle for chemotherapy. Here, we adopted a methyl-tert-butyl ether (MTBE)-based extraction method to simultaneously extract small polar molecules and lipophilic metabolites for nontargeted metabolomics of multidrug-resistant breast cancer cell line MCF-7/ADR and its parental cell line MCF-7/S by ultra-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry. Distinctly different metabolic features were shown between MCF-7/ADR cells and MCF-7/S on the basis of multivariate analyses. 17 potential biomarkers were identified. And these potential biomarkers were mainly correlated with cell membrane lipids composition, cell signaling regulated by lipids, and anti-oxidation ability. The studies of cellular ultrastructure and morphology by in situ atomic force microscopy (AFM) also demonstrated the cellular membrane changed along with the MDR. We expect that this study could provide a new method for monitoring drug resistance during clinical chemotherapy and be useful for the development of drugs to overcome the MDR.
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