No abstract

MicroRNAs (miRNAs) are well‐known as powerful regulators of gene expression, with their potential to serve for immunology widely researched in mammals and birds but rarely in fishes. To better understand fish immunology behavior, we herein investigated nine immune‐related miRNAs that were reported in other animals, as well as five related cytokine factors and lysozyme (LZM) in the liver, anterior kidney, and spleen of Channel Catfish Ictalurus punctatus after being stimulated by lipopolysaccharides (LPS) and β‐glucan. We also predicated the potential targets of these miRNAs via bioinformatics and further investigated nine of them via quantitative real‐time PCR. Results showed that expressions of the nine miRNAs were quickly changed in varying extent after stimulation by LPS, especially for miR‐122, miR‐142a, miR‐155, and miR‐223, which were significantly changed in spleen, and the same occurred for the LZM and three cytokine factors TNF‐α, IFN‐γ and TLR2. Compared with LPS, although most of the miRNAs and the cytokine genes were also affected by β‐glucan, the extent of the effect was weak. Bioinformatics analysis revealed many immune‐related targets of the miRNAs, with some of them reported by previous studies. For the nine investigated target genes, seven targets (77.8%) were significantly upregulated after the stimulation of LPS. It therefore can be inferred that the immune‐related miRNAs, LZM, and cytokine factors elicited quick immune responses of Channel Catfish to LPS stimulation as in other animals, but the regulation mechanism of miRNAs might be complex and diverse. This research will contribute to a better understanding will support further immunology research in fishes.

This study evaluates how white mulberry (Morus alba L.) leaf extracts affect the growth, antioxidant activity, and immune response in Nile tilapia Oreochromis niloticus. Mulberry leaf extracts were obtained through aqueous extraction (AE) and ethanol extraction (EE). Powder of mulberry leaf (PML) was added directly to feed and compared with the effects of feeds supplemented with the different extracts. Fish were divided into eight groups for an 8-week feeding trial where they were fed the basal diet or supplementation with 10% PML, 10% AE, 20% AE, 40% AE, 10% EE, 20% EE, or 40% EE. The inclusion of mulberry leaf extract obtained with either method showed better effects on fish growth performance, antioxidant activities and acid phosphatase activity (ACP) in serum, immune cytokine expression, and intestinal morphology as compared with controls or fish fed the 10% PML diet. The specific growth rate was significantly higher in the 10% AE, 10% EE, and 20% EE groups compared with all other groups (P<0.05). Catalase activity was significantly greater in most groups fed an extract, and in the 10% PML group, when compared with controls. Similarly, ACP, interleukin (IL)-1, and IL-2 expression was significantly increased in groups fed an extract, and in the 10% PML group, when compared with controls (P<0.05). IL-1, IL-2, IL-10, and Toll-like receptor 2 expression was significantly greater in the 10% EE group than in the 10% PML and 10% AE groups (P<0.05). Villus length in the middle intestine was significantly increased in the 10% AE and 10% EE groups compared with controls and the 10% PML group (P<0.05). Thus, 10% mulberry leaf ethanol extract added to feed is recommended for enhancing the growth rate and health of cultured Nile tilapia.