Phylogeny of cytokines: molecular cloning and expression analysis of sea bass Dicentrarchus labrax interleukin-1 beta

In this paper the cloning of interleukin-1 beta (IL-1 beta) from the fish D icentrarchus labrax (sea bass) is described. Using degenerate primers desig ned from known IL-1 beta sequences, a cDNA fragment was amplified by PCR an d elongated by 3' and 5' RACE to give the full-length coding sequence for s ea bass IL-1 beta. The cDNA is 1292 bp, lacks a putative ICE cut site, and codes for a deduced peptide of 29.4 kDa with a pI of 5.1. Sequence analysis showed highest amino acid similarity with rainbow trout (62%), Xenopus (46 %), and carp (45.5%) IL-1 beta sequences. Expression studies show that sea bass IL-1 beta can be upregulated by bacterial lipopolysaccharide both in v itro and in vivo in leucocytes from blood, head-kidney, spleen, gills and l iver, whereas the IL-1 beta transcript was not detectable in thymus and gut -associated lymphoid tissue. Northern blot analysis with head-kidney leucoc yte RNA showed a main LPS-upregulated band at 1.3 kb, and two minor bands a t 0.9 and 3.0 kb, respectively. Phylogenetic comparisons with IL-1 beta fro m other vertebrates is presented. (C) 2001 Academic Press.