The cytokine IL-1β from the crocodile icefish Chionodraco hamatus (Perciformes: Channichthyidae)

The immune system of the so-called crocodile icefishes, members of the family Channichthyidae, has been recently investigated to study its morphological and functional organisation, to evidence the presence of specific immune humoral responses, and to analyse immunoglobulin genes. In the present study, primers designed to conserved regions of interleukin-1 beta were used for the homology cloning of the icefish Chionodraco hamatus IL-1 beta gene. The full length cDNA consists of 1,289 nucleotides that translate in a single reading frame to give a predicted 250-amino acid molecule. The sequence had the highest nucleotide identity (75.7%) and amino acid similarity (69.8%) and identity (63.2%) with turbot IL-1 beta, followed by European sea bass and gilthead sea bream. Studies of IL-1 beta expression indicated that this molecule is induced, both in vitro and in vivo, by bacterial lipopolysaccharide (LPS). Finally, similar to other Perciformes IL-1 beta genes, the C. hamatus gene is organised in five exons and four introns.