Search

Corn gluten meal (CGM) is used as a protein source in aquafeeds. However, the potential for replacing fish meal (FM) with CGM in abalone feeds has not been adequately evaluated. A 110-day feeding trial was conducted to evaluate effects of replacing FM with CGM on abalone Haliotis discus hannai (initial weight: 21.83 ± 0.25 g). The control diet (CGM0) was designed to contain 20% of FM. The other four isonitrogenous (about 30% of crude protein) and isolipidic (about 4% of crude lipid) experimental diets were formulated with CGM protein replacing 25%, 50%, 75% and 100% of dietary FM protein, respectively. The five experimental diets were named as CGM0, CGM25, CGM50, CGM75 and CGM100, respectively. Results showed that no significant differences were found in survival rate among all the groups. Weight gain rate (WGR) of abalone in the CGM100 group was significantly lower than that in the control group. There were no significant differences in WGR among the CGM25, CGM50, CGM75 and the control groups. The increasing dietary CGM inclusion level elevated the operational taxonomic units, ACE estimator and Chao1 estimator, and changed the intestinal microbiota composition in abalone. The activities of trypsin, alanine transaminase, aspartate transaminase and Na+, K+-ATPase in digestive gland were significantly decreased when replacement level over 50%. The increasing dietary CGM inclusion level significantly downregulated the expressions of ribosomal S6 protein kinase (s6k), mammalian target of rapamycin (mtor) and eukaryotic translation initiation factor 4E (eif4e) in digestive gland. The CGM75 and CGM100 groups had significant lower activities of catalase and lysozyme in cell-free hemolymph and digestive gland. In conclusion, CGM could replace 75% of dietary FM (equivalent to 16.2% of CGM inclusion level in the diet) without significantly affecting the growth of abalone. However, high inclusion levels of CGM in diets (> 10.8%) had negative effects on intestinal microbiota, mTOR pathway and immunity in abalone.

Excessive perfluorooctane sulfonate (PFOS) in natural water ecosystem has the potential to detrimentally affect immune system, but little is known of such effects or underlying mechanisms in fish. In the present study, we evaluated the effects of PFOS on growth performance, organizational microstructure, activities of immune-related enzymes and expressions of immune-related genes in male zebrafish (Danio rerio) exposed to different concentrations of 0, 0.02, 0.04 and 0.08 mg/L of PFOS for 7, 14, and 21 days or cotreatment with PFOS and PDTC to investigate the effects of PFOS on immune system and the potential toxic mechanisms caused by PFOS. The results indicated that PFOS accumulated in livers after exposure, and remarkably elevations were found in three exposure groups compared with the control group at three stages. The growth of the adult zebrafish in the experiments was significantly inhibited, the microstructures of liver were serious damaged. The ROS levels were remarkably increased. The activities of ACP, AKP, and lysozyme were obviously decreased, while the activities of MPO and NF-κB were significantly increased. The expressions of immune-related mRNA were significantly affected. After co-treatment with PFOS and PDTC, the growth inhibition, the morphological damage, the ROS induction, and the expressions of immune-related mRNA were reversed. Taken together, the results indicated that PFOS can significantly inhibit the growth, disturb the immune system by changing the normal structure of liver, the activities of immune-related enzymes, and a series of gene transcriptions involved in immune regulation in liver of male zebrafish. PFOS-induced pro-inflammatory effect of hepatocytes was observed, and the involvement of NF-κB signaling pathway was participated in its action mechanism. These findings provide further evidence that PFOS interferes with the immune regulation of liver of male zebrafish under in vivo conditions.