Analysis of Quantitative Trait Loci for Pathogenic Strain Pi-1 of Resistance to Rice False Smut in Rice(Oryza sativa)

In order to identify the resistant gene of rice false smut in rice, a recombi- nant inbred line （RILs） population with 157 lines derived from an inter-subspecies cross of Daguandao/IR28 by the single seed descent method was used to detect quantitative trait loci （QTLs） conferring resistance to strain Pi-1 of rice false smut caused by Usti/aginoiclea virens （Cooke） Takahashi in 2012 and 2013. The disease rate indexes of the two parents and 157 RILs caused by the strain Pi-1 of rice false smut were scored and the QTLs for rice false smut resistance were detected accordingly by QTL Cartographer software. Seven QTLs controlling false smut re- sistance were detected on chromosomes 2, 7, 8, 11 and 12, respectively, with the phenotypic variance of 8.5%-17.2%. There were four QTLs detected in 2012 and 2013, respectively, and only one QTL was found in both two years, the phenotypic variation explained by this individual QTL was 13.5% and 17.2%, and the additive effects of this QTL contributed to the 9.9% and 14.3% decrease of disease index and therefore the disease resistance increased. The direction of the additive effects at five loci qFsr2a, qFsr8a, qFsr8b, qFsr11 and qFsr12 coincided with that predicted by phenotypes of the parents, and the IR28 alleles at these loci had positive effect against rice false smut while the negative effects were found in Daguandao alleles at qFsr2b and qFsr7. The qFsr11 should be useful in rice breeding for resistance to rice false smut in marker-assisted selection （MAS） program.

Pathogenic effects of O-polysaccharide from Shigella flexneri strain

AIM To investigate the specific pathogenesis ofO-polysaccharide (O--PS) which is on the outermembrane of lipopolysaccharides (LPS) fromShigella fi^eri.METHODS The O--PS was isolated and purifiedfrom Shigella nexneri 5 MgoT by enzymatichydrolysis and gel chromatography. Effects ofO--PS were observed by in vitro experiment,(HeLa cell Culture ), and in vivo experiment(rabbit lieal loop assay).RESULTS ID vitro and in vivo e-cP6riments withthe purified O--PS from Shigells flexnefi revealedthat the O--PS alone was toxic to Hela cells andcaused mucosal inflammation and hemorrhagicexudation in lieal loop of rabbit.DISCUSSION O--PS might b6 one of the factorscausing diarrhea and its mechanism wasdifferent from endotoxin reaction of LPS. Themolecular mechanism of O-PS need furtherstudies.

Optimization of cryopreservation of pathogenic microbial strains

The preservation of pathogenic microbial strains is of great significance for basic research in microbiology and utilization of microbial resources.Appropriate preservation methods can maintain high survival rate and genetic stability of pathogenic microbial strains for a long time.This study summarizes the current status of preservation of strains,discusses the limitations and damaging factors of cryopreservation and prospects for optimization,and explores the mechanism of cryopreservation of strains.Our main objective is to provide a reference for the long-term effective preservation of microbial resources and guarantee of national biosafety.

First Complete Genome Sequence of a Probiotic Enterococcus faecium Strain T-110 and Its Comparative Genome Analysis with Pathogenic and Non-pathogenic Enterococcus faecium Genomes

Enterococci bacteria are important in environmental, food and clinical microbiology. Enterococcus faecium is a nosocomial pathogen that causes bacteremia, endocarditis and other infections. It is among the most prevalent organisms encountered in hospital-associated infections accounting for approximately 12% of nosocomial infections in the USA （Linden and Miller, 1999）. However, certain strains of E. faecium are not only non-pathogenic but also have beneficial effects on human health with probiotic potential. For example, E. faecium T-110 is a consortium member in several probiotic products including BIO-THREE~ which is widely prescribed for human, animal and aqua-cultural use. This strain was originally developed by TOA Pharmaceuticals in Japan, and later used in the probiotic products of several other companies.