Evasion of complement-mediated killing is a common phenotype for many different types of pathogens, but the mechanism is still poorly understood. Most of the clinic isolates of Edwardsiella tarda, an important pathogen infecting both of human and fish, are commonly found serum-resistant. To explore the potential mechanisms, we applied gas chromatography-mass spectrometry (GC-MS)-based metabolomics approaches to profile the metabolomes of E. tarda EIB202 in the presence or absence of serum stress. We found that tricarboxylic acid (TCA) cycle was greatly enhanced in the presence of serum. The quantitative real-time PCR (qRT-PCR) and enzyme activity assays validated this result. Furthermore, exogenous succinate that promotes the TCA cycle increased serum resistance, while TCA cycle inhibitors (bromopyruvate and propanedioic acid) that inhibit TCA cycle, attenuated serum resistance. Moreover, the enhanced TCA cycle increased membrane potential, thus decreased the formation of membrane attack complex at cell surface, resulting serum resistance. These evidences suggested a previously unknown membrane potential-dependent mechanism of serum resistance. Therefore, our findings reveal that pathogen mounts a metabolic trick to cope with the serum complement-mediated killing.

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Soy protein adhesives are good candidates for the replacement of formaldehyde-based adhesives due to environmental concerns. However, poor water resistance has limited their application. This study was conducted to improve the water resistance of a soy-protein adhesive intended for plywood by polyethylene glycol (PEG) with different molecular weights. Ethylene glycol (EG), diethylene glycol (DEG), 400-, 2000-, and 10000-dalton polyethylene glycols were used as additives to soy protein isolate (SPI). The hydrogen bonding interaction, thermal properties, wettabilities on poplar veneer, and adhesion properties of the blended adhesives were investigated. Results showed that improving the wettability and intermolecular hydrogen bonding, induced by ethylene glycol, increased the wet adhesion strength by 30%. Higher-molecular weight polyethylene glycol imposed a decrease in adhesion due to its poor water resistance. Based on the present results, it is proposed to improve the water resistance of soy adhesives by introducing hydrophilic polyols, which also could simultaneously improve surface wetting and wet adhesion.

This work proposes a class of one-dimensional analogue chaotic signals which have perfect statistical properties. A non-invertible transformation is introduced to generate a class of binary (symbolic) chaotic sequences with desired distribution function and correlation function. These binary chaotic secure sequences are proven to have near-ideal linear complexity and infinite large discrete correlation dimension, thus they cannot be reconstructed by linear-feedback shift-register (LFSR) techniques or nonlinear dynamics (NLD) forecasting in finite order.

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