Hot water extract of Pleurotus pulmonarius stalk waste enhances innate immune response and immune-related gene expression in red hybrid tilapia Oreochromis sp. following challenge with pathogen-associated molecular patterns

Effects of dietary Hericium erinaceus extract on growth, nutrient utilization, hematology, expression of genes related immunity response, and disease resistance of Nile tilapia (Oreochromis niloticus)

In recent years, there has been a growing focus on using herbal extracts as immune enhancers for aquatic species, replacing antibiotics. In the present study, the effects of dietary supplementation of Hericium erinaceus extract (HE) on growth, feed utilization, hematology, expression of immunity-related genes, and immune responses in Nile tilapia infected by Streptococcus agalactiae were examined. A total of 240 Nile tilapia with an average body weight of 17.28 ± 0.01 g were fed diets enriched with different levels of HE: 0 (HE0), 0.1 (HE0.1), 1.0 (HE1.0), and 5.0 (HE5.0) g/kg. The results showed that growth parameters, feed conversion ratio, and organosomatic indexes were not linearly or quadratically affected by HE supplementation. Fish fed HE0.1 and HE1.0 increased protein efficiency ratio and protein productive values with significant linear and quadratic effects of HE enrichment. In addition, dietary supplementation of HE quadratically increased whole-body protein content. Red blood cell, white blood cell, and hematocrit were linearly and quadratically increased by HE supplementation. HE also linearly and quadratically decreased LDL cholesterol and linearly decreased the total cholesterol levels. Stress markers, serum glucose, and cortisol levels were linearly and/or quadratically decreased in HE-fed fish. The relative mRNA expression of tnf-α, il-1β, il-6, and il-10 were upregulated in the HE0.1 and HE1.0 groups, while dietary supplementation of HE significantly decreased hsp70cb1 mRNA expression in all groups. After feeding dietary HE supplementation for 10 weeks, fish were intraperitoneally injected with pathogenic S. agalactiae. A high survival after challenge was found in all HE supplementation groups with the highest percent survival observed in the HE1.0 and HE5.0 groups. Our findings represent that supplementation of 1 g/kg of HE (HE1.0) could obtain the greatest effects on immunity and survival of Nile tilapia. In addition, the present study also showed that dietary supplementation of HE can improve protein utilization, hematology, expression of genes related to immunity, stress markers, and resistance of Nile tilapia against pathogenic bacterial infection.

Eco-innovative aquafeeds biofortified with Asparagopsis taxiformis to improve the resilience of farmed white seabream (Diplodus sargus) to marine heatwave events

Extreme weather events, like marine heatwaves (MHWs), are becoming more frequent and severe due to climate change, posing several challenges to marine ecosystems and their services. As disease outbreaks are often prompted by these acute phenomena, it is essential to develop eco-innovative strategies that can efficiently improve farmed fish resilience, especially under sub-optimal rearing conditions, thereby ensuring a sustainable aquaculture production. This study aimed to unveil farmed juvenile white seabream (Diplodus sargus, 28.50 ± 1.10 g weight, n = 150) immune and antioxidant responses under a category II MHW in the Mediterranean Sea (+4 °C, 8 days of temperature increase plus 15 days of plateau at the peak temperature) and to investigate whether a 30 days period of prophylactic biofortification with Asparagopsis taxiformis (1.5 %, 3 % and 6 %) enhanced fish resilience to these extreme events. Several biomarkers from different organization levels (individual, cellular, biochemical and molecular) were assessed upon 30 days of biofortification (T30), exposure (after 8 days of temperature increase + 15 days at peak temperature, T53) and recovery (8 days of temperature decrease, T61) from the MHW. Results showed that MHW negatively affected the fish physiological status and overall well-being, decreasing specific growth rate (SGR) and haematocrit (Ht) and increasing erythrocyte nuclear abnormalities (ENAs) and lipid peroxidation (LPO). These adverse effects were alleviated through biofortification with A. taxiformis. Seaweed inclusion at 1.5 % was the most effective dose to minimize the severity of MHW effects, significantly improving immune responses of D. sargus (i.e. increased levels of immunoglobulin M, peroxidase activity and lysozyme expression) and modulating antioxidant responses (i.e. decreased LPO, catalase and glutathione S-transferase activity). These findings confirm that A. taxiformis is a functional ingredient of added value to the aquaculture industry, as its inclusion in marine fish diets can beneficially modulate fish immunity and resilience under optimal and adverse rearing conditions.

Effect of Agaricus bisporus Polysaccharides (ABPs) on anti-CCV immune response of channel catfish

Herein, the effects of Agaricus bisporus Polysaccharides (ABPs) on anti-channel catfish virus (CCV) infections to promote their application in channel catfish culture were explored. Transcriptome and metabolome analyses were conducted on the spleen of a CCV-infected channel catfish model fed with or without ABPs. CCV infections upregulated many immune and apoptosis-related genes, such as IL-6, IFN-α3, IFN-γ1, IL-26, Casp3, Casp8, and IL-10, and activated specific immunity mediated by B cells. However, after adding ABPs, the expression of inflammation-related genes decreased in CCV-infected channel catfish, and the inflammatory inhibitors NLRC3 were upregulated. Meanwhile, the expression of apoptosis-related genes was reduced, indicating that ABPs can more rapidly and strongly enhance the immunity of channel catfish to resist viral infection. Moreover, the metabonomic analysis showed that channel catfish had a high energy requirement during CCV infection, and ABPs could enhance the immune function of channel catfish. In conclusion, ABPs can enhance the antiviral ability of channel catfish by enhancing immune response and regulating inflammation. Thus, these findings provided new insights into the antiviral response effects of ABPs, which might support their application in aquaculture.

Can Agri-Food Waste Be a Sustainable Alternative in Aquaculture? A Bibliometric and Meta-Analytic Study on Growth Performance, Innate Immune System, and Antioxidant Defenses

The agri-food industry generates a large amount of waste every year, which is both an environmental and economic problem, especially for the countries in charge of its disposal. Over the years, there has been a growing interest especially in plant waste, since they are rich in compounds with high nutritional and nutraceutical value. As a result, several scientific disciplines are investigating their alternative use in the formulation of dietary supplements for human or animal use, or as biostimulants for agricultural purposes. In this review, using a meta-analytical approach, we summarize the main and most recent findings related to the use of plant waste as potential ingredients in dietary supplementation for fish grown under controlled experimental conditions. In particular, in this review, it has been highlighted that plant waste may have not only positive effects on growth performance, but also beneficial effects on modulation of the innate immune system and antioxidant defenses. Finally, the bibliometric study and a mapping provide an overview of the recent publications, showing the research strength across the country, the number of potential collaborations among institutions, and the main research focus, demonstrating how this topic is growing in interest, especially in Europe.

Effects of dietary rambutan (Nephelium lappaceum L.) peel powder on growth performance, immune response and immune-related gene expressions of striped catfish (Pangasianodon hypophthalmus) raised in biofloc system

This study aimed to evaluate the effects of rambutan peel powder (RP) on growth, skin mucosal and serum immunities, and immune-related gene expression of striped catfish (Pangasianodon hypophthalmus) reared in a biofloc system. Three hundred fingerlings (17.14 ± 0.12 g fish^-1) were randomly selected and assigned to five treatments corresponding to five diets: 0 g kg^-1 (control - RP0); 10 g kg^-1 (RP10); 20 g kg^-1 (RP20); 40 g kg^-1 (RP40), and 80 g kg^-1 (RP80) for 8 weeks. At weeks 4 and 8 post-feeding, growth, skin mucus, and serum immunity parameters were determined, whereas immune-related gene expressions were performed at the end of the feeding trial. Based on the results, skin mucus lysozyme (SML) and skin mucus peroxidase (SMP) were significantly higher in fish fed the RP diets compared to the control diet (P < 0.05). The highest SML and SMP levels were observed in fish fed RP40 diet, followed by RP20, RP80, RP10, and RP0. Fish-fed RP diets had higher serum lysozyme and serum peroxidase activities, with the highest value found in the RP40 diet (P < 0.05), followed by RP20, RP80, and RP10. Similarly, immune-related gene expressions (IFN2a, IFN2b, and MHCII) in the liver were significantly up-regulated in fish fed RP40. Up-regulation (P < 0.05) of IL-1, IFN2a, IFN2b, and MHCII genes was also observed in fish intestines, with the highest values observed in fish fed RP40 diet, followed by RP10, RP20, RP80, and RP0. Fish-fed diet RP diets also showed enhanced growth and FCR compared to the control, with the highest values observed in fish fed diet RP40. However, no significant differences in survival rates were found among diets. In conclusion, dietary inclusion of RP at 40 g kg^-1 resulted in better growth performance, immune response, and immune related gene expressions of striped catfish (Pangasianodon hypophthalmus).

Comparison of immune defense and antioxidant capacity between broodstock and hybrid offspring of juvenile shrimp (Macrobrachium nipponense): Response to acute ammonia stress

Ammonia is a major environmental pollutant in the aquatic system that poses a great threat to the health of shrimp. Macrobrachium nipponense, as one of the large-yield farmed shrimp, is facing germplasm degradation. Genetic improvement through hybridization is one of the effective methods to solve this problem. However, there are few studies on the effects of ammonia nitrogen on the germplasm resources of M. nipponense. In this study, the broodstock populations (Dianshan, DS) and hybrid offspring (DS ♀ × CD [Changjiang, CJ ♂ × Dongting, DT ♀], SCD) were exposed to 0, 5, or 20 mg/L of ammonia for 96 h. The survival rate of the SCD group was greater than the DS group, although there were no significant differences in weight gain rate and length gain rate (p > 0.05). The number of positive cells and apoptosis rates in the DS group were significantly greater than in the SCD group after ammonia exposure (p < 0.05). As the ammonia concentration increased, the antioxidant enzyme activities in the SCD group were significantly higher than DS group, while the hepatotoxicity enzyme activities in the SCD group were significantly lower than DS group (p < 0.05). The trends in the expression of antioxidant- and immune-related genes were generally consistent with the activities of antioxidant enzymes. Our study found that the hybrid population had stronger stress resistance than their parent populations at the same ammonia concentration. This study confirms our speculation that hybrid population has a greater advantage in antioxidant immunity, which also provides reference for the follow-up study of chronic ammonia toxicity.