Identification and expression of IL-1β in the endangered Dabry’s sturgeon (Acipenser dabryanus)

Abstract

Dabry’s sturgeon (Acipenser dabryanus), mainly distributed in the upper Yangtze River, is considered as a rare and endangered species in China. To date, its innate immune system remains largely undetermined. In the present study, we identified an interleukin 1 beta (IL-1β) gene with a 6-exon/5-intron structure from Dabry’s sturgeon. The predicted protein sequence has a typical IL-1 family signature, containing 12 β-strands and no signal peptide. Although the predicted amino acid sequence encoded by the IL-1β gene had low sequence identity and similarity to other fish IL-1βs, the Dabry's sturgeon IL-1 β protein clustered together with proteins from other fish IL-1β type II group homologous proteins. The different expression levels of the IL-1β gene in various embryonic developmental stages implied that IL-1β might be subject to maternal transmission and mediate embryonic development. Tissue distribution analysis revealed that the IL-1β was ubiquitously expressed (especially in the skin and gill), suggesting that the IL-1β could play a vital role in the first immune barrier under normal conditions. Transcriptional analysis indicated that the IL-1β gene transcription levels in spleen leukocytes following polyinosinic-polycytidylic acid (Poly I:C) and lipopolysaccharide (LPS) stimulation were 3-fold and 12-fold higher than those in the control, respectively. The different IL-1β gene responses to poly I:C and LPS suggested differences in defense mechanisms against viruses and bacteria in Dabry’s sturgeon.