E. rhusiopathiae is the causative agent of erysipelas in animals and erysipeloid in humans, but its pathogenicity is poorly understood. To identify virulence factors associated with E. rhusiopathiae and screen engineered vaccine candidates, we used proteomics and transcriptomics to compare the highly virulent strain HX130709 with an isogenic avirulent derivative, HX130709a. 1,299 proteins and 1,673 transcribed genes were identified and 1,292 of the proteins could be associated with genes. In a comparison between HX130907 and HX130709a, 168 proteins and 475 genes exhibited differences in regulation level. Among these, levels for 61 proteins and transcripts were positively or negatively correlated. Gene Ontology (GO) analysis suggests that many of the down-regulated proteins in the attenuated strain have catalytic or binding functions. Potential protein-protein interactions suggest that some of the down-regulated proteins may regulate PTS, GMP synthase and ribosomal proteins. Morphological results showed that HX130709 and HX130709a have similar colony and capsule morphology. Growth curves and pyruvate measurements suggest that TCA cycle and saccharide phosphorylation levels were decreased and gluconeogenesis was increased in HX130709a. Our study confirms that SpaA and neuraminidase, but not hyaluronidase and capsule, are associated with virulence in E. rhusiopathiae. We conclude that the virulence of E. rhusiopathiae may be associated with slow reactions of the TCA cycle and down-regulation of selected proteins.

Neuroblastoma, one of the most common types of cancer in childhood, is commonly treated with surgery, radiation and chemotherapy. However, prognosis and survival remain poor for children with high‑risk neuroblastoma. Therefore, the identification of novel, effective therapeutic targets is necessary. N‑Myc, a proto‑oncogene protein encoded by the v‑myc avial myelocytomatosis viral oncogene neuroblastoma derived homolog (MYCN) gene, is associated with tumorigenesis. In the present study, the effect of N‑Myc silencing on MYCN‑amplified CHP134 and BE‑2C neuroblastoma cells was evaluated, and the underlying molecular mechanism was investigated. N‑Myc was successfully knocked down using an N‑Myc‑specific small interfering RNA, the efficacy of interference efficiency confirmed by reverse transcription‑quantitative polymerase chain reaction and western blotting. Cell viability was evaluated by MTT assay and apoptosis was measured by ELISA assay. The results indicated that MYCN silencing significantly decreased cell viability and promoted apoptosis. Subsequently, the expression levels of key Wnt/β‑catenin signaling pathway proteins were detected by western blotting, and MYCN silencing was demonstrated to inhibit Wnt/β‑catenin signaling, decreasing the expression ofanti‑apoptosis proteins and increasing the expression of pro‑apoptosis protein. This suggested that N‑Myc regulated survival and growth of CHP134 and BE‑2C neuroblastoma cells, potentially through Wnt/β‑catenin signaling. Furthermore, associated proteins, N‑Myc and STAT interactor and dickkopf Wnt signaling pathway inhibitor 1, were demonstrated to be involved in this regulation. Therefore, N‑Myc and its downstream targets may provide novel therapeutic targets for the treatment of neuroblastoma.

Haemophilus parasuis (H. parasuis) is a common commensal Gram-negative extracellular bacterium in the upper respiratory tract of swine, which can cause Glässer's disease in stress conditions. Research on the pathogenicity of H. parasuis has mainly focused on immune evasion and bacterial virulence factors, while few studies have examined the interactions of H. parasuis and its host. Autophagy is associated with the replication and proliferation of many pathogenic bacteria, but whether it plays a role during infection by H. parasuis is unknown. In this study, an adenovirus construct expressing GFP, RFP, and LC3 was used to infect H. parasuis. Western blotting, laser confocal microscopy, and electron microscopy showed that Hps5 infection induced obvious autophagy in PK-15 cells. In cells infected with strains of H. parasuis differing in invasiveness, the levels of autophagy were positively correlated with the presence of alive bacteria in PK-15 cells. In addition, autophagy inhibited the invasion of Hps5 in PK-15 cells. Autophagy related genes Beclin, Atg5 and Atg7 were silenced with RNA interference, the results showed that autophagy induced by H. parasuis infection is a classical pathway. Our observations demonstrate that H. parasuis can induce autophagy and that the levels of autophagy are associated with the presence of alive bacteria in cells, which opened novel avenues to further our understanding of H. parasuis-host interplay and pathogenesis.

Geosmin and 2-MIB are responsible for the majority of earthy and musty events related to the drinking water. These two odorants have extremely low odor threshold concentrations at ng L−1 level in the water, so a simple and sensitive method for the analysis of such trace levels was developed by headspace solid-phase microextraction coupled to gas chromatography/mass spectrometry. In this study, the orthogonal experiment design L32 (49) was applied to arrange and optimize experimental conditions. The optimum was the following: temperatures of extraction and desorption, 65°C and 260°C, respectively; times of extraction and desorption, 30 min and 5 min, respectively; ionic strength, 25% (w/v); rotate-speed, 600 rpm; solution pH, 5.0. Under the optimized conditions, limits of detection (S/N = 3) were 0.04 and 0.13 ng L−1 for geosmin and 2-MIB, respectively. Calculated calibration curves gave high levels of linearity with a correlation coefficient value of 0.9999 for them. Finally, the proposed method was applied to water samples, which were previously analyzed and confirmed to be free of target analytes. Besides, the proposal method was applied to test environmental water samples. The RSDs were 2.75%~3.80% and 4.35%~7.6% for geosmin and 2-MIB, respectively, and the recoveries were 91%~107% and 91%~104% for geosmin and 2-MIB, respectively.

No abstract