title: cDNA cloning and mRNA expression of a tandem-repeat galectin (PoGal2) from the pearl oyster, Pinctada fucata.
abstract: Galectins can recognize and specifically bind to β-galactoside residues, playing crucial roles in innate immune responses of vertebrates and invertebrates. We cloned the cDNA of a tandem-repeat galectin from the pearl oyster Pinctada fucata (designated as PoGal2). PoGal2 cDNA is 1347 bp long and consists of a 5'-untranslated region (UTR) of 3 bp, a 3'-UTR of 297 bp with one cytokine RNA instability motif (ATTTA), and an open reading frame of 1047 bp, encoding a polypeptide of 349 amino acids, with an estimated molecular mass of 38.1 kDa and a theoretical isoelectric point of 8.5. PoGal2 contains two carbohydrate recognition domains (CRDs); both have the conserved carbohydrate-binding motifs H-NPR and WG-EE. PoGal2 shares 50.6 and 50.9% identity with those of abalone (Haliotis discus) and the Manila clam (Venerupis philippinarum), respectively. Phylogenetic analysis revealed that the tandem-repeat galectins formed two clades for the different species. Molluscan tandem-repeat galectins were clustered into a single clade, and nematode tandem-repeat galectins were clustered into another single clade. In both clades, CRD-N and CRD-C were divided into different groups. PoGal2 mRNA was constitutively expressed in all tissues analyzed, and the expression level of PoGal2 mRNA was found to be significantly up-regulated in digestive glands, gills and hemocytes after Vibrio alginolyticus stimulation/infection. Expression profile analysis showed that the expression level of PoGal2 mRNA was significantly up-regulated at 8, 12 and 24 h after V. alginolyticus infection. These results suggest that PoGal2 is a constitutive and inducible acute-phase protein involved in the innate immune response of pearl oysters.
authors.affiliation: Division of Aquaculture and Biotechnology, South China Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Guangzhou, China.
authors.forename: D C
authors.initials: DC
authors.lastname: Zhang
authors.forename: Y T
authors.initials: YT
authors.lastname: Hu
authors.forename: H Y
authors.initials: HY
authors.lastname: Guo
authors.forename: S G
authors.initials: SG
authors.lastname: Cui
authors.forename: T F
authors.initials: TF
authors.lastname: Su
authors.forename: S G
authors.initials: SG
authors.lastname: Jiang
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D003001:Cloning, Molecular; D018076:DNA, Complementary; D020224:Expressed Sequence Tags; D005697:Galactosides / Q000378:metabolism; D037161:Galectins / Q000737:chemistry / Q000235:genetics*; D020869:Gene Expression Profiling; D005786:Gene Expression Regulation; D015723:Gene Library; D007113:Immunity, Innate; D008969:Molecular Sequence Data; D010802:Phylogeny; D049911:Pinctada / Q000145:classification / Q000235:genetics*; D012333:RNA, Messenger / Q000096:biosynthesis; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D020080:Tandem Repeat Sequences
chemical_list: D018076:DNA, Complementary; D005697:Galactosides; D037161:Galectins; D012333:RNA, Messenger; C007816:beta-galactoside