title: Immunoglobulin T from sea bass (Dicentrarchus labrax L.): molecular characterization, tissue localization and expression after nodavirus infection.
abstract: Immunoglobulins (Igs) are fundamental components of the adaptive immune system of vertebrates, with the IgT/IgZ isotype specific of Teleosts. In this paper we describe the identification of an IgT heavy chain from the European sea bass (Dicentrarchus labrax L.), its molecular characterization and tissue mRNA localization by in situ hybridization.
  
  
  
  Sea bass IgT consists of 552 aa (Accession Number KM410929) and it contains a putative 19 amino acids long signal peptide and one potential N-glycosylation site. The C-region consists of four CHdomains; each contains the cysteine and tryptophan residues required for their correct folding. Based on the recent sequencing of sea bass genome, we have identified five different genomic contigs bearing exons unequivocally pertaining to IgT (CH2, CH3 and CH4), but none corresponded to a complete IgH locus as IgT sequences were found in the highly fragmented assembled genomic regions which could not be assigned to any major scaffold. The 3D structure of sea bass IgT has been modelled using the crystal structure of a mouse Ig gamma as a template, thus showing that the amino acid sequence is suitable for the expected topology referred to an immunoglobulin-like architecture. The basal expression of sea bass IgT and IgM in different organs has been analysed: gut and gills, important mucosal organs, showed high IgT transcripts levels and this was the first indication of the possible involvement of sea bass IgT in mucosal immune responses. Moreover, sea bass IgT expression increased in gills and spleen after infection with nodavirus, highlighting the importance of IgT in sea bass immune responses. In situ hybridization confirmed the presence of IgT transcripts in the gut and it revealed a differential expression along the intestinal tract, with a major expression in the posterior intestine, suggesting the hindgut as a site for the recruitment of IgT+cells in this species. IgT transcripts were also found in gill filaments and parallel lamellae and, for the first time, we identified scattered IgT positive cells in the liver, with a strong signal in the hepatic parenchyma.
  
  
  
  In conclusion, we performed a full molecular characterization of IgT in sea bass that points out its possible involvement in mucosal immune responses of this species.
authors.affiliation: Department for Innovation in Biological, Agro-food and Forest Systems, University of Tuscia, Largo dell'Università snc, 05100, Viterbo, VT, Italy. fbuono@unitus.it.
authors.forename: Francesco
authors.identifier: 0000-0001-8045-5651
authors.initials: F
authors.lastname: Buonocore
authors.affiliation: Department for Innovation in Biological, Agro-food and Forest Systems, University of Tuscia, Largo dell'Università snc, 05100, Viterbo, VT, Italy.
authors.forename: Valentina
authors.initials: V
authors.lastname: Stocchi
authors.affiliation: Department for Innovation in Biological, Agro-food and Forest Systems, University of Tuscia, Largo dell'Università snc, 05100, Viterbo, VT, Italy.
authors.forename: Noelia
authors.initials: N
authors.lastname: Nunez-Ortiz
authors.affiliation: Department for Innovation in Biological, Agro-food and Forest Systems, University of Tuscia, Largo dell'Università snc, 05100, Viterbo, VT, Italy.
authors.forename: Elisa
authors.initials: E
authors.lastname: Randelli
authors.affiliation: Department of Life Sciences, University of Trieste, Via Giorgieri 5, 34127, Trieste, TS, Italy.
authors.forename: Marco
authors.initials: M
authors.lastname: Gerdol
authors.affiliation: Department of Life Sciences, University of Trieste, Via Giorgieri 5, 34127, Trieste, TS, Italy.
authors.forename: Alberto
authors.initials: A
authors.lastname: Pallavicini
authors.affiliation: Institute of Food Science, CNR, Via Roma, 64, 83100, Avellino, AV, Italy.
authors.forename: Angelo
authors.initials: A
authors.lastname: Facchiano
authors.affiliation: Department for Innovation in Biological, Agro-food and Forest Systems, University of Tuscia, Largo dell'Università snc, 05100, Viterbo, VT, Italy.
authors.forename: Chiara
authors.initials: C
authors.lastname: Bernini
authors.affiliation: Department for Innovation in Biological, Agro-food and Forest Systems, University of Tuscia, Largo dell'Università snc, 05100, Viterbo, VT, Italy.
authors.forename: Laura
authors.initials: L
authors.lastname: Guerra
authors.affiliation: Department for Innovation in Biological, Agro-food and Forest Systems, University of Tuscia, Largo dell'Università snc, 05100, Viterbo, VT, Italy.
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Scapigliati
authors.affiliation: Department for Innovation in Biological, Agro-food and Forest Systems, University of Tuscia, Largo dell'Università snc, 05100, Viterbo, VT, Italy.
authors.forename: Simona
authors.initials: S
authors.lastname: Picchietti
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001492:Bass / Q000235:genetics / Q000276:immunology* / Q000821:virology*; D003001:Cloning, Molecular; D005393:Fish Diseases / Q000235:genetics / Q000276:immunology* / Q000821:virology; D029941:Fish Proteins / Q000737:chemistry / Q000235:genetics / Q000276:immunology*; D020869:Gene Expression Profiling; D005786:Gene Expression Regulation; D018928:Immunity, Mucosal; D007136:Immunoglobulins / Q000737:chemistry / Q000235:genetics / Q000276:immunology*; D008958:Models, Molecular; D030381:Nodaviridae / Q000276:immunology*; D010802:Phylogeny; D012327:RNA Virus Infections / Q000235:genetics / Q000276:immunology / Q000662:veterinary* / Q000821:virology; D016415:Sequence Alignment
chemical_list: D029941:Fish Proteins; D007136:Immunoglobulins
keywords: IgT; In situ hybridisation; Mucosal immunity; Sea bass; Tissue expression