Technical University of Denmark, DTU Aqua, Section for Aquaculture, The North Sea Research Centre, DK-9850 Hirtshals, Denmark; Nofima, The Norwegian Institute of Food, Fisheries & Aquaculture Research, Ås, Norway.
Technical University of Denmark, DTU Aqua, Section for Aquaculture, The North Sea Research Centre, DK-9850 Hirtshals, Denmark.
Fish Shellfish Immunol. 2018 Jan;72:418-425. doi: 10.1016/j.fsi.2017.11.025. Epub 2017 Nov 13.
Circadian rhythm is emerging as an important regulator of immune functions. However, there is a paucity of information on the influence of this biological phenomenon in the antimicrobial factors in teleost fish. This study investigated the dynamics and interplay of serum-mediated bacterial killing activity and immune defence factors throughout the light:dark (LD) cycle in rainbow trout (Oncorhynchus mykiss). The juvenile fish came from two different emergence time fractions (i.e., late and early) that were believed to exhibit behavioural and physiological differences. Serum collected during the day from fish (mean ± SD: 39.8 ± 6.3 g) reared under 14L:10D photoperiod demonstrated bactericidal activity against Flavobacterium psychrophilum, Yersinia ruckeri and Aeromonas salmonicida subsp. salmonicida of varying magnitude, but no significant differences between the emergence fractions were observed. A day-night comparison in the same batch of fish revealed time-of-day dependence in the bactericidal activity against F. psychrophilum and Y. ruckeri amongst emergence fractions. A group of fish (63.3 ± 4.7 g) from each fraction was entrained to 12L:12D photoperiod for 21 days to investigate whether serum bactericidal activity exhibited daily rhythm. Serum-mediated bacterial killing activity against F. psychrophilum and Y. ruckeri displayed significant daily rhythm in both emergence fractions, where the peak of activity was identified during the light phase. Moreover, several serum defence factors manifested variations during the LD cycle, where anti-protease (ANTI) and myeloperoxidase (MPO) activities exhibited significant daily oscillation. However, there were no remarkable differences in the daily changes of serum factors amongst emergence fractions. Acrophase analysis revealed that the peaks of activity of alkaline phosphatase (only in late fraction), ANTI, lysozyme (only in early fraction) and MPO were identified during the light phase and corresponded with the period when serum-mediated bacterial killing activity was also at its highest. The daily dynamics of bactericidal activity and immune defence factors displayed positive correlation, particularly between MPO and, the two pathogens (i.e., F. pyschrophilum and Y. ruckeri). Taken together, the study revealed that serum-mediated bacterial killing activity and immune defence factors remarkably varied during the LD cycle in rainbow trout. In addition, the two emergence fractions displayed nearly comparable immunological profiles.
昼夜节律正在成为免疫功能的重要调节因子。然而，关于这种生物现象对硬骨鱼类抗菌因子的影响，信息仍然匮乏。本研究调查了虹鳟（Oncorhynchus mykiss）在光暗（LD）周期中血清介导的杀菌活性和免疫防御因子的动态和相互作用。这些幼鱼来自两个不同的出膜时间分数（即晚期和早期），据信它们表现出行为和生理上的差异。在 14L:10D 光周期下饲养的鱼在白天采集的血清（平均值±标准差：39.8±6.3g）对杀弗氏柠檬酸杆菌、鲁氏耶尔森氏菌和杀鲑气单胞菌亚种的杀菌活性有不同程度的差异，但在出膜分数之间没有观察到显著差异。同一批鱼的昼夜比较显示，在出膜分数之间，针对杀弗氏柠檬酸杆菌和鲁氏耶尔森氏菌的杀菌活性存在昼夜依赖性。从每个分数中选择一组鱼（63.3±4.7g）适应 12L:12D 光周期 21 天，以研究血清杀菌活性是否表现出每日节律。针对杀弗氏柠檬酸杆菌和鲁氏耶尔森氏菌的血清介导的杀菌活性在两个出膜分数中都表现出明显的每日节律，活性峰值出现在光照阶段。此外，几种血清防御因子在 LD 周期中表现出变化，其中抗蛋白酶（ANTI）和髓过氧化物酶（MPO）活性表现出明显的每日波动。然而，在出膜分数之间，血清因子的每日变化没有显著差异。相位分析显示，碱性磷酸酶（仅在晚期分数中）、ANTI、溶菌酶（仅在早期分数中）和 MPO 的活性峰值出现在光照阶段，与血清介导的杀菌活性也处于最高水平的时期相对应。杀菌活性和免疫防御因子的日动态呈正相关，特别是 MPO 与两种病原体（即杀弗氏柠檬酸杆菌和鲁氏耶尔森氏菌）之间。总之，本研究表明，在虹鳟的 LD 周期中，血清介导的杀菌活性和免疫防御因子显著变化。此外，这两个出膜分数表现出几乎相似的免疫特征。
