Enzyme-based targeted disintegration of biofilms formed by food-borne pathogens: a review / 生物工程学报

Food-borne pathogens pose great risks to human health and public safety, and the formation of biofilm exacerbates their pathogenicity and antimicrobial resistance. Enzymes can target special substances in the biofilm to disintegrate the biofilm of food-borne pathogens, which has great potential for applications. This review summarized the progress of using enzymes to disintegrate the biofilms of food-borne pathogens, highlighting quorum-quenching enzymes, C-di-GMP metabolic enzymes, as well as extracellular matrix hydrolases. Finally, challenges and perspectives on developing enzymes into effective products for disintegrating the biofilms of food-borne pathogens were discussed.

Applications of simulated gastro-intestinal model in foodborne pathogens: tolerance and pathogenesis / 生物工程学报

We evaluated the tolerance and pathogenesis of foodborne pathogens with a simulated gastro-intestinal tract model that simulates the chemical, physical and biological effects of human digestion process under laboratory conditions. This could be used to study the tolerance, pathogenesis, gut microbiota interaction and vaccine development of foodborne pathogens, so as to contribute to control and treatment of foodborne pathogens. This review introduces the applications of simulated gastro-intestinal tract model tp evaluate foodborne pathogens, which includes in-vitro static gastro-intestinal model, in-vitro dynamic gastro-intestinal model, conventional animal model and humanized animal model. And the concepts and characteristics of all models are described in detail. Also, the shortcomings of existing models are analyzed, and improvements of artificial gastro-intestinal tract model are prospected. In conclusion, this review could provide comprehensive data for promoting the progress of studying tolerance and pathogenesis of foodborne pathogens.

Protective effects of cimetidine against oxidative stress induced by low-dose irradiation / 解放军医学杂志

Objects To study the protective effects of cimetidine against oxidative stress in rats induced by cumulative low-dose irradiation.Methods Sixty SD rats were randomly divided into 6 groups (10 each):normal control group,model control group,lentinan group [89mg/(kg.d)] and 3 dose groups of cimetidine.After oral administration,all the rats were exposed to γ-ray irradiation 8 hours/day for 12 days,and sacrificed on the 13th day.The activities of superoxide dismutase (SOD),glutathione peroxidase (GPx),catalase (CAT) and the content of malondialdehyde (MDA) in serum,liver,thymus and spleen were determined.By using the superoxide anion radical system,hydroxyl radical system,H2O2 radical system,oxidation system of linoleic acid induced by alkane radical system and diphenyl picryl hydrazinyl radical (DPPH) radical system,the antioxidation activities of cimetidine were detected.Results The activities of SOD in liver and thymus decreased significantly,the GPx activity in serum,liver and spleen decreased significantly and MDA level in serum,liver and spleen increased significantly after 0.3Gy cumulative ionizing radiation.Cimetidine enhanced the activities of antioxidant enzymes in serum and organs,and reduced the MDA level.In a certain concentration range,cimetidine had different scavenging effects onto these radical systems,and showed good performance in hydroxyl radical.Conclusion Cimetidine can effectively ameliorate the oxidative stress from low-dose cumulative irradiation by scavenging free radicals,increase the activity of antioxidant enzymes and reduce the content of lipid peroxidation products,thus presents a potential radio protective effect.

Prediction of Promoter Motifs in Virophages / 病毒学报

Virophages have crucial roles in ecosystems and are the transport vectors of genetic materials. To shed light on regulation and control mechanisms in virophage--host systems as well as evolution between virophages and their hosts, the promoter motifs of virophages were predicted on the upstream regions of start codons using an analytical tool for prediction of promoter motifs: Multiple EM for Motif Elicitation. Seventeen potential promoter motifs were identified based on the E-value, location, number and length of promoters in genomes. Sputnik and zamilon motif 2 with AT-rich regions were distributed widely on genomes, suggesting that these motifs may be associated with regulation of the expression of various genes. Motifs containing the TCTA box were predicted to be late promoter motif in mavirus; motifs containing the ATCT box were the potential late promoter motif in the Ace Lake mavirus . AT-rich regions were identified on motif 2 in the Organic Lake virophage, motif 3 in Yellowstone Lake virophage (YSLV)1 and 2, motif 1 in YSLV3, and motif 1 and 2 in YSLV4, respectively. AT-rich regions were distributed widely on the genomes of virophages. All of these motifs may be promoter motifs of virophages. Our results provide insights into further exploration of temporal expression of genes in virophages as well as associations between virophages and giant viruses.