Dietary non-protein energy source regulates antioxidant status and immune response of barramundi (Lates calcarifer)

The combined effects of temperature and salinity on the digestion and respiration metabolism of Pinctada fucata

The combined effects of temperature and salinity on the digestion and respiration metabolism of Pinctada fucata were evaluated via response surface methodology and box-benhnken design under laboratory condition. Results indicated that the primary and secondary effects of salinity and temperature had significant effects on amylase (AMS) of P. fucata (P < 0.05)., The digestive enzyme reached the maximum activity when temperature was 26 °C. The AMS and trypsin (TRYP) increased at first, and then decreased with increasing temperature. The Lipase (LPS) was positively correlated with either salinity or temperature. Salinity had no significant effect on TRYP as a primary effect (P > 0.05), but had a significant effect on TRYP as a secondary effect (P < 0.01). These effects were completely opposite to the effect of temperature on pepsin (PEP) as primary and secondary effects. The combined effects of salinity and temperature on AMS, TRYP and PEP were significant (P < 0.01), but had no significant effect on LPS (P > 0.05). The primary, secondary and interaction effects of salinity had significant effects on NKA (Na⁺-K⁺-ATPase) of P. fucata (P < 0.05), and NKA presented a U-shaped distribution with increasing salinity. The quadratic and interactive effects of temperature had a significant effect on AKP (P < 0.05), and AKP showed a U-shaped distribution with increasing temperature. Lactate dehydrogenase (LDH) activity decreased at first, and then increased when temperature and salinity changed from 20 to 30 °C and 23-33 ‰, respectively. The expression of GPX gene affected by temperature in gills may be delayed compared with that in hepatopancreas, and its expression is tissue-specific. The appropriate digestion and respiratory metabolism index models were established under the combined temperature and salinity conditions. The optimization results showed that the optimal combination of temperature and salinity was 26.288 °C/28.272‰. The desirability was 0.832. Results from the present study will provide a theoretical reference for shellfish culture affected by environmental interactions and the establishment of related index models.

Influence of bamboo vinegar powder (BVP) enriched diet on antioxidant status, immunity level, and pro-anti-inflammatory cytokines modulation in Asian sea bass, Lates calcarifer (Bloch 1790) against Vibrio anguillarum

Effect of bamboo vinegar powder (BVP) on growth, immunity, disease resistance, and immune-related gene expressions in juvenile Asian sea bass (barramundi), Lates calcarifer against Vibrio anguillarum was investigated. V. anguillarum infected fish fed by 2g BVP kg^-1 diet exhibited significant growth, albumin (AB), serum total protein (TP), and globulin (GB) levels. Similarly, enhanced lysozyme (LZM), phagocytic (PC), anti-protease (AP), respiratory burst (RB), bactericidal (BC) activities and total immunoglobulin (Ig) levels were observed in fish fed 2g BVP kg^-1. In addition, use of 2g BVP kg^-1 in diet modulated several immune related gene expressions against Vibrio disease. This study exhibited a positive effect of dietary 2g BVP kg^-1 diet on hemato-biochemical and immunological responses, which enhance the immunocompetence and health status of L. calcarifer against V. anguillarum infection.

Immune Responses of Asian Seabass Lates calcarifer to Dietary Glycyrrhiza uralensis

To understand the impacts of dietary Glycyrrhiza uralensis on the immune responses of Lates calcarifer, the expression of immune-related genes including crp, c-3, c-4, mtor, mlst-8, eif4e, hsp-70, hsp-90, il-8il-8, il-10, tgfβ1, tnf, ifn-γ1, and mxf in L. calcarifer juveniles was evaluated in this study. Fish were fed experimental diets with G. uralensis levels of 0%, 1%, 3%, and 5% for 56 days. The results showed that dietary G. uralensis could improve the growth and survival of L. calcarifer and regulate the immune-related genes' expression in L. calcarifer. Dietary G. uralensis significantly upregulated the expression level of crp, mtor, hsp-90, c-3, and c-4 genes in the liver of L. calcarifer, while hsp-70 gene expression was nearly downregulated. It did not upregulate the expression of elf4e and mlst-8 in the 1% and 3% inclusion groups, but it was the exact opposite in the 5% inclusion group. G. uralensis significantly affected the expression of il-8, il-10, tnf, ifn-γ1, mxf, and tgfβ1 in the head kidney of L. calcarifer. G. uralensis upregulated the expression of tnf and tgfβ1 consistently, but ifn-γ1 was at a low expression level. The expression of il-8 and il-10 was upregulated in the 1% group, while it was downregulated in the 5% group. The results from the present study indicate that dietary G. uralensis appeared to improve the immune function of L. calcarifer, and the optimum inclusion level should be between 1-3%.