Five restriction endonucleases were used to digest genomic DNA from 5 isolates of Trichinella spiralis obtained from Changchun, Tianjin, Xian, Henan and Yunnan. All the isolates were secured from pigs except the Chang...Five restriction endonucleases were used to digest genomic DNA from 5 isolates of Trichinella spiralis obtained from Changchun, Tianjin, Xian, Henan and Yunnan. All the isolates were secured from pigs except the Changchun strain which came from dog. The DNA fragments digested by endonuclease were separated by agarose gel electrophoresis. The Changchun isolate had a EcoRI band at 1. 12kb and a DraI band at 1. 97kb which were unique to this isolate. A cloned specific repetitive DNA sequence (1. 12kb) from the Changchun strain was selected to prepare a probe for the Southern blotting of EcoRI restriction DNA fragments for the 5 isolates. The 1.12kb hybridizing band did not appear except in the Changchun isolate.These results seem to indicate that there are differences between the isolates obtained from hosts in different geographical regions.展开更多
The genes encoding type II DNA topoisomerases were investigated in Giardia lamblia genome, and a type IIA gene,GlTop 2 was identified. It is a single copy gene with a 4476 bp long ORF without intron. The deduced amino...The genes encoding type II DNA topoisomerases were investigated in Giardia lamblia genome, and a type IIA gene,GlTop 2 was identified. It is a single copy gene with a 4476 bp long ORF without intron. The deduced amino acid sequence shows strong homology to eukaryotic DNA Top 2. However, some distortions were found, such as six insertions in the ATPase domain and the central domain, a -100 aa longer central domain; a ~200 aa shorter C-terminal domain containing rich charged residues. These features revealed by comparing with Top 2 of the host, human, might be helpful in exploiting drug selectivity for antigiardial therapy. Phylogenetic analysis of eukaryotic enzymes showed that kinetoplastids, plants, fungi, and animals were monophyletic groups, and the animal and fungi lineages shared a more recent common ancestor than either did with the plant lineage; microsporidia grouped with fungi. However, unlike many previous phylogenetic analyses, the ''amitochondriate'' G. lamblia was not the earliest branch but diverged after mitochondriate kinetoplastids in our trees. Both the finding of typical eukaryotic type IIA topoisomerase and the phylogenetic analysis suggest G, lamblia is not possibly as primitive as was regarded before and might diverge after the acquisition of mitochondria. This is consistent with the recent discovery of mitochondrial remnant organelles in G. lamblia.展开更多
AIM: To investigate the role of host and bacterial arginases in the colonization of mice by Helicobacter pylori (H.pylori).METHODS: H.pylori produces a very powerful urease that hydrolyzes urea to carbon dioxide and a...AIM: To investigate the role of host and bacterial arginases in the colonization of mice by Helicobacter pylori (H.pylori).METHODS: H.pylori produces a very powerful urease that hydrolyzes urea to carbon dioxide and ammonium,which neutralizes acid.Urease is absolutely essential to H.pylori pathogenesis;therefore,the urea substrate must be in ample supply for urease to work efficiently.The urea substrate is most likely provided by arginase activity,which hydrolyzes L-arginine to L-ornithine and urea.Previous work has demonstrated that H.pylori arginase is surprisingly not required for colonization of wild-type mice.Hence,another in vivo source of the critical urea substrate must exist.We hypothesized that the urea source was provided by host arginase Ⅱ,since this enzyme is expressed in the stomach,and H.pylori has previously been shown to induce the expression of murine gastric arginase Ⅱ.To test this hypothesis,wild-type and arginase (rocF) mutant H.pylori strain SS1 were inoculated into arginase Ⅱ knockout mice.RESULTS: Surprisingly,both the wild-type and rocF mutant bacteria still colonized arginase Ⅱ knockout mice.Moreover,feeding arginase Ⅱ knockout mice the host arginase inhibitor S-(2-boronoethyl)L-cysteine (BEC),while inhibiting > 50% of the host arginase Ⅰ?activity in several tissues,did not block the ability of the rocF mutant H.pylori to colonize.In contrast,BEC poorly inhibited H.pylori arginase activity.CONCLUSION: The in vivo source for the essential urea utilized by H.pylori urease is neither bacterial arginase nor host arginase Ⅱ;instead,either residual host arginase Ⅰ?or agmatinase is probably responsible.展开更多
Endophytes are beneficial microbes that are capable of promoting growth, besides protecting colonized plants against plant pathogens. These microbes are of either bacterial, fungal or actinomycetes in plants. In the s...Endophytes are beneficial microbes that are capable of promoting growth, besides protecting colonized plants against plant pathogens. These microbes are of either bacterial, fungal or actinomycetes in plants. In the study, the endophytic bacteria isolated from sugarcane with their characterization related to plant growth promotion and pathogen suppression have been reported. Roots, shoots and leaves of rooted tissue culture plantlets of sugarcane cultivars of 87A298 and 2009A107 were excised aseptically and isolated endophytic bacterial strains. The strains were identified using 16S rRNA gene sequence based homology. Molecular characterization of these strains was carried out for presence of antimicrobial genes. The results showed that the endophytes isolated from sugarcane tissue culture plantlets were of the genera Bacillus （B. amyloliquefaciens, B. subtilis, B. cereus, B. safensis, B. siamensis, B. aryabhattai, B. flexus and B. velezensis） and Paenibacillus pabuli. There were three antimicrobial peptides （AMPs） producing genes of bacilysin, bacillomycin and fengycin in B. amyloliquefaciens （SE1, SE7）, B. siamensis （SE4, SE16）, B. subtilis （SE2, SE3） and B. velezensis （SE15）. The biochemical characterization assays showed that some of these strains could produce hydrogen cyanide （HCN）, protease, cellulase and indole acetic acid （IAA）. Few strains （SE1 and SE4） were phosphate solubilizers, whereas nine isolates were found to be diazotrophs. Most of the bacterial isolates were found antagonistic to Fusarium sacchari, the sugarcane wilt pathogen under in vitro conditions. Overall, the results suggested the scope and potentiality of sugarcane endophytic bacteria, isolated from tissue culture plantlets, in promoting plant growth and suppression of sugarcane pathogen.展开更多
文摘Five restriction endonucleases were used to digest genomic DNA from 5 isolates of Trichinella spiralis obtained from Changchun, Tianjin, Xian, Henan and Yunnan. All the isolates were secured from pigs except the Changchun strain which came from dog. The DNA fragments digested by endonuclease were separated by agarose gel electrophoresis. The Changchun isolate had a EcoRI band at 1. 12kb and a DraI band at 1. 97kb which were unique to this isolate. A cloned specific repetitive DNA sequence (1. 12kb) from the Changchun strain was selected to prepare a probe for the Southern blotting of EcoRI restriction DNA fragments for the 5 isolates. The 1.12kb hybridizing band did not appear except in the Changchun isolate.These results seem to indicate that there are differences between the isolates obtained from hosts in different geographical regions.
基金supported by Grants (30070362, 30170135,30021004) the National Natural Science Foundationof China and Grants (KSCX2-SW-101C, STZ-00-23)the Chinese Academy of Sciences.
文摘The genes encoding type II DNA topoisomerases were investigated in Giardia lamblia genome, and a type IIA gene,GlTop 2 was identified. It is a single copy gene with a 4476 bp long ORF without intron. The deduced amino acid sequence shows strong homology to eukaryotic DNA Top 2. However, some distortions were found, such as six insertions in the ATPase domain and the central domain, a -100 aa longer central domain; a ~200 aa shorter C-terminal domain containing rich charged residues. These features revealed by comparing with Top 2 of the host, human, might be helpful in exploiting drug selectivity for antigiardial therapy. Phylogenetic analysis of eukaryotic enzymes showed that kinetoplastids, plants, fungi, and animals were monophyletic groups, and the animal and fungi lineages shared a more recent common ancestor than either did with the plant lineage; microsporidia grouped with fungi. However, unlike many previous phylogenetic analyses, the ''amitochondriate'' G. lamblia was not the earliest branch but diverged after mitochondriate kinetoplastids in our trees. Both the finding of typical eukaryotic type IIA topoisomerase and the phylogenetic analysis suggest G, lamblia is not possibly as primitive as was regarded before and might diverge after the acquisition of mitochondria. This is consistent with the recent discovery of mitochondrial remnant organelles in G. lamblia.
基金Supported by Public Health Service grant R01-CA101931 (to DJM) from the National Institutes of Health
文摘AIM: To investigate the role of host and bacterial arginases in the colonization of mice by Helicobacter pylori (H.pylori).METHODS: H.pylori produces a very powerful urease that hydrolyzes urea to carbon dioxide and ammonium,which neutralizes acid.Urease is absolutely essential to H.pylori pathogenesis;therefore,the urea substrate must be in ample supply for urease to work efficiently.The urea substrate is most likely provided by arginase activity,which hydrolyzes L-arginine to L-ornithine and urea.Previous work has demonstrated that H.pylori arginase is surprisingly not required for colonization of wild-type mice.Hence,another in vivo source of the critical urea substrate must exist.We hypothesized that the urea source was provided by host arginase Ⅱ,since this enzyme is expressed in the stomach,and H.pylori has previously been shown to induce the expression of murine gastric arginase Ⅱ.To test this hypothesis,wild-type and arginase (rocF) mutant H.pylori strain SS1 were inoculated into arginase Ⅱ knockout mice.RESULTS: Surprisingly,both the wild-type and rocF mutant bacteria still colonized arginase Ⅱ knockout mice.Moreover,feeding arginase Ⅱ knockout mice the host arginase inhibitor S-(2-boronoethyl)L-cysteine (BEC),while inhibiting > 50% of the host arginase Ⅰ?activity in several tissues,did not block the ability of the rocF mutant H.pylori to colonize.In contrast,BEC poorly inhibited H.pylori arginase activity.CONCLUSION: The in vivo source for the essential urea utilized by H.pylori urease is neither bacterial arginase nor host arginase Ⅱ;instead,either residual host arginase Ⅰ?or agmatinase is probably responsible.
文摘Endophytes are beneficial microbes that are capable of promoting growth, besides protecting colonized plants against plant pathogens. These microbes are of either bacterial, fungal or actinomycetes in plants. In the study, the endophytic bacteria isolated from sugarcane with their characterization related to plant growth promotion and pathogen suppression have been reported. Roots, shoots and leaves of rooted tissue culture plantlets of sugarcane cultivars of 87A298 and 2009A107 were excised aseptically and isolated endophytic bacterial strains. The strains were identified using 16S rRNA gene sequence based homology. Molecular characterization of these strains was carried out for presence of antimicrobial genes. The results showed that the endophytes isolated from sugarcane tissue culture plantlets were of the genera Bacillus （B. amyloliquefaciens, B. subtilis, B. cereus, B. safensis, B. siamensis, B. aryabhattai, B. flexus and B. velezensis） and Paenibacillus pabuli. There were three antimicrobial peptides （AMPs） producing genes of bacilysin, bacillomycin and fengycin in B. amyloliquefaciens （SE1, SE7）, B. siamensis （SE4, SE16）, B. subtilis （SE2, SE3） and B. velezensis （SE15）. The biochemical characterization assays showed that some of these strains could produce hydrogen cyanide （HCN）, protease, cellulase and indole acetic acid （IAA）. Few strains （SE1 and SE4） were phosphate solubilizers, whereas nine isolates were found to be diazotrophs. Most of the bacterial isolates were found antagonistic to Fusarium sacchari, the sugarcane wilt pathogen under in vitro conditions. Overall, the results suggested the scope and potentiality of sugarcane endophytic bacteria, isolated from tissue culture plantlets, in promoting plant growth and suppression of sugarcane pathogen.
