title: Identification and characterization of the first reptilian CD9, and its expression analysis in response to bacterial infection.
abstract: In this study, a CD9 homologue in a reptile, Chinese soft-shelled turtle, has been cloned and identified for the first time. The full-length cDNA of turtle CD9 was 1146bp and contained a 672bp open reading frame (ORF) coding for a protein of 224 amino acids. Four transmembrane domains (TMs) divided the turtle CD9 into several parts: short N-, C-termini, an intracellular loop and two (small and large) extracellular loops (SEL and LEL). A CCG motif, a potential N-linked glycosylation site and 10 cysteine residues were well conserved. The deduced amino acid sequence analysis showed that the turtle CD9 shared 82% identity to duck CD9. Most of the differences were found in the LEL. Phylogenetic analysis showed that the turtle CD9 sequence clustered together with bird CD9 sequence. RT-PCR analysis showed that turtle CD9 was ubiquitously expressed in liver, spleen, kidney, heart, blood and intestine tissues of un-infected turtles. Real-time PCR analysis further indicated that after Aeromonas hydrophila infection, the turtle CD9 mRNA was up-regulated in various tissues at 8h, and significantly up-regulated during 8h to 7d. These results indicated that turtle CD9 may be involved in anti-bacterial immune response.
authors.affiliation: Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, China.
authors.forename: Xiuxia
authors.initials: X
authors.lastname: Zhou
authors.forename: Hong
authors.initials: H
authors.lastname: Feng
authors.forename: Qionglin
authors.initials: Q
authors.lastname: Guo
authors.forename: Heping
authors.initials: H
authors.lastname: Dai
mesh_terms: D016980:Aeromonas hydrophila / Q000276:immunology*; D000595:Amino Acid Sequence; D000818:Animals; D015703:Antigens, CD / Q000737:chemistry / Q000235:genetics / Q000276:immunology*; D001483:Base Sequence; D017124:Conserved Sequence; D005786:Gene Expression Regulation; D006801:Humans; D008562:Membrane Glycoproteins / Q000737:chemistry / Q000235:genetics / Q000276:immunology*; D008969:Molecular Sequence Data; D010802:Phylogeny; D060245:Tetraspanin 29; D014426:Turtles / Q000276:immunology* / Q000382:microbiology*
chemical_list: D015703:Antigens, CD; C554869:CD9 protein, human; D008562:Membrane Glycoproteins; D060245:Tetraspanin 29