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This experiment aimed to study the effects on liver tissue structure and immune performance of grass carp Ctenopharyngodon idellus when the common reed Phragmites australis is in its diet, instead of wheat Triticum aestivum L. Seventy-two healthy grass carps (145.52 ± 2.56 g) were randomly divided into three groups according to their body weight. Fishes in each group were fed an essential diet with 0% (control group), 50% and 100% (test group) common reed, instead of wheat, respectively. After feeding for 41 days, the changes of serum biochemical indices, liver tissue structure and immune related indices of grass carp were detected. The results showed that, compared with the control group, the activities of serum alanine transaminase (ALT) and aspartate transaminase (AST) in the substitution groups were significantly increased (p < 0.05), but still at a normal level. The contents of total protein, albumin and globulin did not change significantly (p > 0.05). Compared with the control group, the liver cells of grass carp in the substitution groups had clear boundaries, tight arrangement and less vacuolation. The contents of serum interleukin-1 (IL-1) and complement 3 (C3) in the 100% substitution group were significantly higher than those in the control group (p < 0.05), and the contents of liver IL-1 and total complement (CH50) in the 100% substitution group were significantly higher than those in the control group (p < 0.05). The contents of IL-1, C3 in serum and IL-1, CH50 in liver in the 50% substitution group were significantly higher than those in the control group (p < 0.05). The mRNA relative expression levels of C3, IL-1, MHC-I and interferon (IFN) in the head-kidney, kidney, liver and spleen of grass carp were significantly affected by feeding the grass carp with different common reed substitution ratios (p < 0.05). In summary, common reed, instead of wheat, in feed can improve the liver tissue structure, and increase the non-specific immune response level, of grass carp.

A representative echinoderm, the sea cucumber Apostichopus japonicus has a special regeneration mechanism. The sea cucumber has no specific immune tissues or organs. Coelomocytes of sea cucumbers are involved in their cellular and humoral immunity. In this study, expression profiles of the main immune-related factors in sea cucumber coelomocytes were detected during coelomocyte regeneration after evisceration in A. japonicus. Immune-related factors Cu/Zn superoxide dismutase (Cu/Zn SOD), Catalase (CAT), C-type lysozyme (C-LYZ), Cathepsin D (CTSD), Melanotransferrin (MTF), Toll-like receptor (TLR), C-type lectin (C-LCT), Complement 3 (C3), Myeloid differentiation factor 88 (MYD88), Nuclear factor kappa-B (NF-κB), NF-κB inhibitor (IKB), TNF receptor-associated factor 6 (TRAF6), Peroxiredoxins (PRX), Nitric oxide synthase(NOS), Caspase-2 (CASP-2), Phenoloxidase (PO), and Glutathione Peroxidase(GPX), Heat shock protein 70 (HSP70) were detected by real-time fluorescent quantitative PCR at different time points during regeneration. The main immune-related genes in sea cucumber coelomocytes were significantly differentially expressed after evisceration, and an upregulation was observed for the majority of the considered genes. In summary, the discharge of viscera had a significant effect on expression of immune-related genes of sea cucumber coelomocytes. The expression level of each gene had a certain correlation with the sea cucumber regeneration process. The results provide reference data for the immune response of coelomocytes during regeneration., Invertebrate Survival Journal, Vol 17 No 1 (2020)