| The term pathogenicity island (PA I) is a new concept in the field of Bacteriology .It has been found in many enterobacteria,it may be associated with the emersion of pathogens and the evolution of bacteric virulence.As a member of PAIs,high pathogenicity island (HPI) encoding a iron uptake system mediatd by siderphore yersiniabactin was first identified in high pathogenic Yersinia and is greatly important genie unit for Yersinia. Rencently,it is found in diarrheagenic E.coli strains.But its define distribution and transference machinery is not clear in E.coli,so that this study will focus on three parts below to discuss the distribution and uptake iron function of Yersina among ETEC,EAggECand EPEC.l.The prevalence of Y.enterocolitica HPI and its integrality in ETEC,EPEC and EAggEC isolated from South of ChinaUsing PCR,DNA situ dot hybrization and sequences analysis assays,93 strains ETEC,1 Ostrains EPEC and five strains EAggEC isolated from diarrheal patients in china were investigated to detect 11 genes of core of Yen HPI,the 32.25%(30/93) ETEC and 30% (3/10) EPEC habored HPI,the five of six EAggEC (83.33%)are positive. It also was identificated that the irpl-5 genes which detected in bacterias of this study is stable,but thefyua,irp8,irp7 and irp6 gene has different distibution in ETEC,EPEC and EAggEC,there are one third positive (33.33%)strains which defected fyua gene,36.67%( 13/30) irp6,53.33%(16/30) irp7 and 10%(3/30) irp8 genes lost in /rp2-positive ETEC,but all of the EPEC and EAggEC strains have they-wa and irp678 genes. Then the irpl,irp2 and fyua genes of ETEC72,EPEC2 and EAggEC3(the numbers were is the serial number of bacterias in this study)which choosed by random were sequenced,the result showing the homology of these sequences is 99%,this suggests that the group genes of irp2-Jyua is conserved in ETEC,EPEC and EAggEC except fyua gene .The sequenced result of ybta showing that the alignment among ETEC,EPEC and EAggEC with Y.enterocolitica is100%,it indicates these E.coli may has the function for synthesed yersiniabactin as the Y. enterocolitica. 2.The delimitation of HPI in the /rp2-positive ETEC,EPEC and EAggECPCR amplification and sequenced were also used in this part. ALL of irf>2-positiwe ETEC,EPEC and EAggEC were amplified by PCR the covering region of the left integratated locus (asn-tRNA and intS) of HPI. Most PCR yielded DNA products with sizes identifical to those of Yersinia enterocolitica except two ETEC strains could not be detected asn-tRNA gene which the site of HPI intergration into bacteial chromosome,the other 28 strains ETEC,3 strains EPEC and 5 strains EAggEC with asn-intB gene. The products of positive PCR indicating that some products (about ten strains ETEC and only one EPEC strains )size of asn-tRNA was smaller than in Yersinia enterocolotica (1100bp instead of the expect 1393bp),this suggesting that these E.coli might have the same machinism with Y.enterocolitica which intergated into the asn-tRNA location,but some strains deleted part of asn-tRNA or lost whole this gene,maybe the HPI had been modified when it was transfered or the HPI integrated another chromosome site.. 3. Detection of iron uptake function of HPI among ETEC,EPEC JEAggEC SDS-PAGE always used to detect protein in many reserchs,in present study this method is also used .All of the positive strains of HPI was detected .There are some new findings different positive strains with different deletion gene segments express different proteins when they at the condition of iron starvation. Only those E. coli strains which contain whole HPI and at the LB broth with the addition of 0.2Mm or 0.4mM -dipyridyl expressed same proteins(HMWPl,HMWP2) with Yen,this phenomenon predict that those E.coli which have different gene deletion bacterias may have another uptake iron system.This study is the first time in China to detect the all gene segments of the core of HPI among E.coli isolated from China patients.Through this study,though some different structures of HPI were found among ETEC,EPEC and EAggEC,th...
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