In order to determine the effect of foreign genes on a transgenic parasite,the pathogenicity and development in chickens of transgenic E.tenella strain TE1,which expresses yellow fluorescent protein (YFP) and dihydrof...In order to determine the effect of foreign genes on a transgenic parasite,the pathogenicity and development in chickens of transgenic E.tenella strain TE1,which expresses yellow fluorescent protein (YFP) and dihydrofolate reductase thymidylate synthase derived from Toxoplasma gondii(TgDHFR-TS), were compared with that of the parental strain BJ.Results indicated that the fecundity of the transgenic parasite(TE1) was reduced at least 4 times relative to that of the BJ strain.Low dosage of the TE1 strain induced less pathogenesis in chickens than did the BJ strain,but chickens inoculated with a higher dosage of TE1 oocysts displayed severe pathogenicity and mortality as did the BJ strain.In addition,trophozoites, the first generation and the second generation meronts and merozoites,microgamonts and macrogamonts of the transgenic parasite TE1 were seen by fluorescence microscopy.More interestingly,not all four sporonts in the sporulating transgenic oocysts express YFP.These findings suggest that the expression of YFP and TgDHFR-TS genes to some extent reduced pathogenicity and reproductive potential of transgenic E.tenella.Recombination between homologous or non-homologous chromosomes occurred during zygotic meiosis in E.tenella strain TE1.展开更多
Aim of this study was to investigate the genotypic distribution of extended-spectrum β-lactamases (ESBLs) and AmpC enzymes among Escherichia coli isolated from farm animals in Chongqing City. 326 E.coli isolates were...Aim of this study was to investigate the genotypic distribution of extended-spectrum β-lactamases (ESBLs) and AmpC enzymes among Escherichia coli isolated from farm animals in Chongqing City. 326 E.coli isolates were obtained from piglets,cattle and chickens.In these isolates,19 ESBLs and 6 AmpC-producing E.coli isolates were detected by preliminary screening and phenotypic identification, and polymerase chain reaction and sequence analysis methods were used to detect ESBLs and AmpCβ-lactamases genes.The results showed that the frequencies of TEM,CTX-M,DHA-1 and CMY-2 genes were 2.15%,5.21%,0.61%and 0.61%,respectively,in E.coli of animal origin in the Chongqing area,and 5 E.coli isolates were found to carry two kinds of genotype.The DHA-1 gene was detected for the first time in a veterinary clinic in China;its GenBank accession number is FJ386455.This study indicated that TEM and CTX-M genes were the predominant genotypes in Chongqing,and the majority of ESBLs and AmpC-producing E.coli isolates were multi-resistant to antibiotics,so they deserve particular attention in veterinary clinics.展开更多
基金supported by the National High Technology Research and Development Program of China(Project No. 2006AA02Z458)the Doctor Startup Foundation of Henan University of Science and Technology(09001350)
文摘In order to determine the effect of foreign genes on a transgenic parasite,the pathogenicity and development in chickens of transgenic E.tenella strain TE1,which expresses yellow fluorescent protein (YFP) and dihydrofolate reductase thymidylate synthase derived from Toxoplasma gondii(TgDHFR-TS), were compared with that of the parental strain BJ.Results indicated that the fecundity of the transgenic parasite(TE1) was reduced at least 4 times relative to that of the BJ strain.Low dosage of the TE1 strain induced less pathogenesis in chickens than did the BJ strain,but chickens inoculated with a higher dosage of TE1 oocysts displayed severe pathogenicity and mortality as did the BJ strain.In addition,trophozoites, the first generation and the second generation meronts and merozoites,microgamonts and macrogamonts of the transgenic parasite TE1 were seen by fluorescence microscopy.More interestingly,not all four sporonts in the sporulating transgenic oocysts express YFP.These findings suggest that the expression of YFP and TgDHFR-TS genes to some extent reduced pathogenicity and reproductive potential of transgenic E.tenella.Recombination between homologous or non-homologous chromosomes occurred during zygotic meiosis in E.tenella strain TE1.
基金supported by Chongqing Natural Science Foundation(CSTC,2007BB0002)
文摘Aim of this study was to investigate the genotypic distribution of extended-spectrum β-lactamases (ESBLs) and AmpC enzymes among Escherichia coli isolated from farm animals in Chongqing City. 326 E.coli isolates were obtained from piglets,cattle and chickens.In these isolates,19 ESBLs and 6 AmpC-producing E.coli isolates were detected by preliminary screening and phenotypic identification, and polymerase chain reaction and sequence analysis methods were used to detect ESBLs and AmpCβ-lactamases genes.The results showed that the frequencies of TEM,CTX-M,DHA-1 and CMY-2 genes were 2.15%,5.21%,0.61%and 0.61%,respectively,in E.coli of animal origin in the Chongqing area,and 5 E.coli isolates were found to carry two kinds of genotype.The DHA-1 gene was detected for the first time in a veterinary clinic in China;its GenBank accession number is FJ386455.This study indicated that TEM and CTX-M genes were the predominant genotypes in Chongqing,and the majority of ESBLs and AmpC-producing E.coli isolates were multi-resistant to antibiotics,so they deserve particular attention in veterinary clinics.
