Molecular characterisation of sea bream (Sparus aurata) transforming growth factor beta1

A transforming growth factor beta1 (TGF beta1) full length cDNA was characterised and sequenced from the head kidney of sea bream (Sparus aurata) previously challenged with a nodavirus. The cloned cDNA of 1778bp contains a predicted open reading frame of 379 amino acids, which includes the mature peptide region of 112 amino acids. The regulating region of the peptide possesses four potential N-linked glycosylation sites (N-X-T/S), as well as an RGD integrin binding site, an RKKR tetrabasic cut site and nine conserved cysteines all characteristic of the TGF beta superfamily. Compared to other teleost TGF beta1 genes, the sea bream TGF beta1 is most closely related to hybrid striped bass (Moronesaxatilis xM. chrysops) TGF beta1 (80% amino acid identity). The genomic organisation of TGF beta1 was determined through the generation of contiguous PCR clones. The sea bream TGF beta1 gene is approximately 3.6kb in length and consists of five coding regions. Two introns are absent in comparison to the genomic organisation of rainbow trout Oncorhynchus mykiss TGF beta1, whilst an additional intron not present in other sequenced TGF beta genes, but present in the trout TGF beta1 gene, is conserved in sea bream.A reverse transcription polymerase chain reaction (RT-PCR) assay was developed to study TGF beta expression in different sea bream tissues. Constitutive TGF beta1 expression was detected in the liver, brain, muscle, kidney, heart, gills and spleen of sea bream, as well as in head kidney macrophages and blood leucocytes.