Comparative study and expression analysis of the interferon gamma gene locus cytokines in Xenopus tropicalis
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- Qi, Z.T. & Nie, P. Immunogenetics (2008) 60: 699. doi:10.1007/s00251-008-0326-y
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Using bioinformatics approach, the genome locus containing interleukin (IL)-22, IL-26, and interferon gamma (IFN-γ) genes has been identified in the amphibian, Xenopus tropicalis. Like that in other vertebrates such as fish, birds, and mammals, the Xenopus IL-22, IL-26, and IFN-γ are clustered in the same chromosome and the adjacent genes are conserved. The genomic structures of the Xenopus IL-22, IL-26, and IFN-γ gene were identical to that of their mammalian counterparts. The Xenopus IL-22 and IL-26 genes contained five exons and four introns while the Xenopus IFN-γ gene consisted of four exons and three introns. The Xenopus IL-22, IL-26, and IFN-γ share 14.1–41.6%, 14.6–31.2%, and 23.7–36.5% identity to their counterparts in other species, respectively. Reverse-transcription polymerase chain reaction (PCR) and real-time quantitative PCR analyses revealed that the expression of IL-22, IL-26, and IFN-γ genes was significantly upregulated after simulation with bacterial polyliposaccharide and/or synthetic double-stranded poly(I:C), suggesting these cytokines like those in other vertebrates play an important role in regulating immune response in Xenopus.