Research
| Title： | Dietary Scenedesmus ovalternus improves disease resistance of overwintering gibel carp (Carassius gibelio) by alleviating toll-like receptor signaling activation |
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| First author： | Xu, Wenjie; Li, Hongyan; Wu, Liyun; Jin, Junyan; Zhu, Xiaoming; Han, Dong; Liu, Haokun; Yang, Yunxia; Xu, Xudong; Xie, Shouqi |
| Journal： | FISH & SHELLFISH IMMUNOLOGY |
| Years： | 2020 |
| DOI： | 10.1016/j.fsi.2019.12.065 |
| Abstract： | This study was conducted to investigate the effect of dietary Scenedesmus ovalternus on the growth and disease resistance of gibel carp (Carassius gibelio) during overwintering. Gibel carp (initial body weight: 90.39 +/- 0.33 g) were fed with diets containing 0% or 4% Scenedesmus ovalternus (DS0 and DS4) for 4 weeks during the early overwintering period, and then all fish were left unfed during the late overwintering period. A bacterial challenge test using Aeromonas hydrophila was subsequently conducted. The 4% Scenedesmus ovalternus diet had no effect on the growth of gibel carp (P > 0.05), but did improve the survival rate after the challenge (P <= 0.05). In the DS0 group, the bacterial challenge decreased the contents of complement 3 (C3), immunoglobulin M (IgM), interleukin 2 (IL2) and tumor necrosis factor alpha (TNF alpha) in fish (P < 0.05); in the DS4 group, the challenge increased total antioxidant capacity (T-AOC) and myeloperoxidase (MPO) activity but decreased IL2 and TNF alpha contents (P < 0.05). The activities of MPO and contents of C3, IgM and TNF alpha were higher in the DS4 group than that fed the DS0 diet after bacterial challenge (P < 0.05). Compared to pre challenge, the expression levels of toll like receptor 2 (TLR2), toll like receptor 3 (TLR3), toll like receptor 4 (TLR4), myeloid differentiation factor 88 (MyD88), Toll/IL-1 receptor domain-containing adaptor protein (TIRAP), TIR-domain-containing adapter-inducing interferon 13 (TRIF), nuclear factor of kappa light polypeptide gene enhancer in B-cells inhibitor a (Ix13a), transforming growth factor beta (TGF beta), interleukin 1 beta (IL1 beta), tumor necrosis factor alpha 1 (TNF alpha 1) and interleukin 10 (IL10) in the head kidney of gibel carp were induced after challenge (P < 0.05). Gibel carp fed the DS4 diet showed lower expression of TGF beta in head kidney before the challenge and lower expression of TLR2, TLR3, TLR4, TIRAP, TRIF, I kappa B alpha, TNF alpha 1, IL10 and TGF beta after the challenge than that fed the DS0 diet (P < 0.05). Overall, Scenedesmus ovalternus supplement enhanced the resistances of gibel carp against A. hydrophila after overwintering via the TLR signaling pathway. |
