Aims: To clone, sequence and characterize the genetic organization of urease genes within urease‐positive thermophilic Campylobacter (UPTC).
Methods and Results: An approx. 5·1‐kbp region encoding a urease gene operon was identified, when recombinant plasmid DNAs from a genomic DNA library of a Japanese isolate (CF89‐12) of UPTC were analysed.
Conclusions: Six closely spaced and putative open reading frames (ORFs) for ureA, ureB, ureE, ureF, ureG and ureH were detected. ATG codons initiated each ORF of the UPTC urease operon except for ureB and ureH, which commenced with the most probable TTG codon. Overlaps were detected between ureA and ureB and also between ureB and ureE. Probable ribosome‐binding sites and a putative ρ‐independent transcriptional termination region were identified. Two putative promoter structures, consisting of consensus sequences at the −35 like and −10 regions were also identified.
Significance and Impact of the Study: Construction of a neighbour‐joining tree based on the nucleotide sequence data of urease genes indicated that UPTC formed a cluster with some Helicobacter organisms separate from the other urease‐producing bacteria, suggesting a commonly shared ancestry between UPTC and Helicobacter urease genes.
Liver resident macrophages designated Kupffer cells (KCs) form the largest subpopulation of tissue macrophages. KCs are involved in the pathogenesis of liver inflammation. However, the role of KCs in the systemic inflammation is still elusive. In this study, we examined whether KCs are involved in not only intrahepatic inflammation but also extrahepatic systemic inflammation. Administration of clodronate liposomes resulted in the KC deletion and in the suppression of liver injury in T cell-mediated hepatitis by ConA as a local acute inflammation model, while the treatment did not influence dextran sulfate sodium- (DSS-) induced colitis featured by weight loss, intestinal shrink, and pathological observation as an ectopic local acute inflammation model. In contrast, KC deletion inhibited collagen-induced arthritis as a model of extrahepatic, systemic chronical inflammation. KC deleted mice showed weaker arthritic scores, less joint swelling, and more joint space compared to arthritis-induced control mice. These results strongly suggest that KCs are involved in not only intrahepatic inflammatory response but also systemic (especially) chronic inflammation.
Cloning, sequencing and characterization of nearly full-length 23S rRNA genes in 12 urease-positive thermophilic Campylobacter (UPTC) isolates were carried out using two novel PCR primer pairs. Nucleotide sequences of the 23S rRNA genes from the 12 isolates were first shown not to carry any intervening sequences (IVSs) in both the 25 and 45 helix regions. Then, two PCR primer sets were designed in silico for amplification of the helix 25 and 45 regions within 23S rRNA gene sequences from Campylobacter lari. No IVSs were identified within the 23S rRNA genes among a total of 53 isolates of C. lari, following PCR amplification, TA cloning and sequencing procedures. Intact 23S rRNA was identified in all 65 C. lari isolates, resulting in no production of the fragmented 23S rRNA. These data suggest that C. lari may not have any opportunity to interact with any other source of IVSs until now, or has been unable to integrate IVSs into their own genomes.
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