Characterization and expression analysis of the complement component 8β from pufferfish (Takifugu rubripes)

Complement 8β (C8β) is a critical component in the complement system, which mediates bacterial lysis and acts as an essential molecule for membrane attack complex (MAC) formation. This study cloned a partial C8β gene by transcriptome sequencing and RACE approaches from pufferfish Takifugu rubripes (designated as Tr-C8β). Tr-C8β had a 3′ untranslated region (UTR) of 112 bp, a putative open reading frame (ORF) of 1761 bp encoding a polypeptide of 586 amino acid residues, with an estimated molecular mass of 65.26 kDa and a predicted isoelectric point (pI) of 7.86. For adult T. rubripes, spatial distribution expression indicated Tr-C8β expressed in all examined tissues with predominant expression in the liver, moderate in muscle, and weak in the brain. Moreover, the expression of Tr-C8β in the liver was significantly upregulated and peaked at 24 h after lipopolysaccharide (LPS) stimulation. For the larval T. rubripes, Tr-C8β mRNA expression increased dramatically during the heartbeat phase and peaked in the hatching prophase, then decreased significantly from 3 to 5 days post hatch (dph), and bottomed at 9 dph. Taken together, all these results suggested that Tr-C8β is an immune factor that might be involved in anti-bacteria response and development in pufferfish