The gram-negative, aerobic, rod-shaped bacterium Aeromonas hydrophila, the causative agent of motile aeromonad septicaemia, has attracted increasing attention due to its high pathogenicity. Here, we constructed the complete genome sequence of a virulent strain, A. hydrophila HX-3 isolated from Pseudosciaena crocea and performed comparative genomics to investigate its virulence factors and quorum sensing features in comparison with those of other Aeromonas isolates. HX-3 has a circular chromosome of 4,941,513 bp with a 61.0% G + C content encoding 4483 genes, including 4318 protein-coding genes, and 31 rRNA, 127 tRNA and 7 ncRNA operons. Seventy interspersed repeat and 153 tandem repeat sequences, 7 transposons, 8 clustered regularly interspaced short palindromic repeats, and 39 genomic islands were predicted in the A. hydrophila HX-3 genome. Phylogeny and pan-genome were also analyzed herein to confirm the evolutionary relationships on the basis of comparisons with other fully sequenced Aeromonas genomes. In addition, the assembled HX-3 genome was successfully annotated against the Cluster of Orthologous Groups of proteins database (76.03%), Gene Ontology database (18.13%), and Kyoto Encyclopedia of Genes and Genome pathway database (59.68%). Two-component regulatory systems in the HX-3 genome and virulence factors profiles through comparative analysis were predicted, providing insights into pathogenicity. A large number of genes related to the AHL-type 1 (ahyI, ahyR), LuxS-type 2 (luxS, pfs, metEHK, litR, luxOQU) and QseBC-type 3 (qseB, qseC) autoinducer systems were also identified. As a result of the expression of the ahyI gene in Escherichia coli BL21 (DE3), combined UPLC-MS/MS profiling led to the identification of several new N-acyl-homoserine lactone compounds synthesized by AhyI. This genomic analysis determined the comprehensive QS systems of A. hydrophila, which might provide novel information regarding the mechanisms of virulence signatures correlated with QS.
2002-02-01·Yi chuan xue bao = Acta genetica Sinica
[Identification of a resistance gene to bacterial blight (Xanthomonas oryzae pv. oryzae) in a somaclonal mutant HX-3 of indica rice].
作者: Dong-Ying Gao ; Zhi-Gang Xu ; Zhi-Yi Chen ; Li-Hua Sun ; Qi-Ming Sun ; Fan Lu ; Bai-Shi Hu ; Yong-Feng Liu
Using the mature embryo of a susceptible rice variety Minghui 63 as the explant, we have obtained a somaclonal mutant HX-3 through selection in vitro, which has showed resistance to bacterial blight. In 8 successive years, the resistance of R1 to R9 generations of HX-3 was identified by ZJ173, a typical bacterial blight strain in Yangtsu River valley, and the results showed that the resistance of HX-3 was stable and heritable. Genetic analysis also indicated that the resistance of HX-3 to bacterial blight was under a dominant gene controlling. Using 32 bacterial blight strains collected in China, Philippines and Japan, the resistance spectrum of HX-3 and other 13 testers with different major dominant resistance genes were tested. Results of 2 years (1999-2000) experiment showed that HX-3 had a broad resistance spectrum, which seemed to be different with those of the other dominant resistance genes identified. Allelic tests were also conducted by crossing HX-3 with IRBB4, IRBB7, CBB12 and IRBB21, and the F2 populations of each of the 4 crosses demonstrated resistant and susceptible plant segregation, indicating that the resistance gene in HX-3 different from Xa-4, Xa-7, Xa-12 and Xa-21. All these results proved that there was a new resistance gene in HX-3. We have designated the new gene as Xa-25(t).
1993-02-01·Acta virologica4区 · 医学
Detection of viral antigens on the surface of cells infected with Japanese encephalitis virus by modified immunofluorescent technique.
4区 · 医学
作者: A K Gupta ; V J Lad ; S N Ghosh
A modified immunofluorescent method employing anti-Japanese encephalitis (JE) virus monoclonal (MoAbs) and polyclonal (immune PF) antibodies was evaluated for the detection of viral antigens expressed on the surface of porcine stable kidney cells infected with JE virus (733913, India). The infected cells showed granular immunofluorescence on the surface with both the MoAbs, Hs-1 and Hx-3 and immune PF 24 hr and 48 hr post virus infection. Interestingly, two strains of JE virus viz. Yoken (Japan) and 755468 (India) which did not react with the MoAb Hs-1 in the standard indirect fluorescent antibody (FA) technique, were positive for surface immunofluorescence (IF) with the same MoAb. Thus, the modified technique will be useful for the detection of more labile and conformational-dependent epitopes which might get lost or denatured by prior fixation of infected cells with acetone.