Molecular cloning of prophenoloxidase and the effects of dietary β-glucan and rutin on immune response in hemocytes of the fleshy shrimp, Fenneropenaeus chinensis

To investigate the effects of dietary beta-glucan (0.5 or 1 g kg(-1) diet: 0.5-BG, 1-BG) and rutin (0.5 or 1 g kg(-1) diet: 0.5-RT, 1-RT) after 10 days in the absence of pathogen challenge on the immune response of Fenneropenaeus chinensis, we determined total hemocyte count (THC) and the expression of four immunerelated genes in hemocytes: those for prophenoloxidase (proP0), peroxinectin (PX), lipopolysaccharide and/or beta-glucan binding protein (LGBP), and c-type lectin (CL). As a prerequisite for subsequent experiments, cDNA encoding proPO of the fleshy shrimp, Fenneropenaeus chinensis (f-proPO) was obtained from hemocytes; it had a full length of 3023bp, with an open reading frame (ORF) of 2061bp, a 105-bp 5'-untranslated region, and a 906-bp 3'-untranslated region containing the poly A signal. The THCs of shrimp fed beta-glucan of 1 g kg(-1) diet, and rutin of 1 g kg(-1) diet were significantly higher than that of the control (P < 0.05). The expression of proPO mRNA was slightly downregulated and that of LoBP mRNA was upregulated (except in 1-RT). PX and CL mRNA remained constitutively expressed in all groups. Our results reveal that beta-glucan and rutin dietary supplements have minimal effect on immune response in the absence of pathogen challenge. (C) 2012 Elsevier Ltd. All rights reserved.