探討發光二極體（LED）對香魚成長、抗氧化及先天免疫之影響

Abstract

本研究目的在探討利用不同波長之發光二極體（LED）改變水體光環境，對香魚幼魚生長、抗氧化力及先天免疫反應之影響。將香魚飼養在不同波長LED照射之箱網中，實驗用魚分為三組，分別為白光LED（全波長；色溫：6000K）、紅光LED（波長：630nm）及藍光LED（波長：450nm）組進行12週照射，光照週期維持12小時光亮及12小時黑暗（12L：12D），每日移除受傷或死亡之個體，並測量投餵時第一次上浮時間；每四週犧牲魚隻進行採樣測量，測定體長體重、脾臟中抗氧化力以及先天免疫相關之基因表現量與蛋白質活性。結果顯示藍光照射飼養條件下體長與體重於第12週時高於白光組，而紅光在第4週開始皆低於白光組；在就餌時間部分則是紅光組就餌時間顯著拉長，顯示該波長處理可能降低就餌意願；三組之間活存率相近。在抗氧化指標上，相對於白光飼養組，超氧岐化酵素（SOD）之mRNA在藍光飼養組中於第8及12週表現有顯著下降，顯示魚體在該條件下可能具有較少的氧化壓力；紅光組之SOD則是第8週時下降而第12週上升，過氧化氫酶（CAT）則是第4週開始至實驗結束皆維持增加的趨勢；SOD活性測試則是與mRNA表現有相同趨勢，顯示出長期使用紅光照射可能會導致氧化壓力上升。在先天免疫方面，藍光組之TNF-α mRNA表現量在實驗時期皆有增加趨勢，紅光組則是於第12週時則顯著上升；IL-1β部分為第4週時藍光與紅光組皆顯著上升，至第12週時藍光與白光組無差異。另外在藍光照射下，第4週之溶菌酶（LZM）mRNA表現顯著下降，而紅光組為第12週下降，與抗氧化能力趨勢相反，兩者之間可能存在著互相影響的關係。綜合上述結果顯示，在飼養香魚之水域光環境會影響魚體生理反應，在藍光照射條件下飼養香魚，在增加成長、抗氧化及先天免疫力方面可獲得較佳的效果。

Light emitting diodes (LEDs) become more popular in fish farming because lighting of certain spectral may promote the growth and innate immune system of fish. In the present study, we reported that the effects of different wavelength (white: 6000k; blue LED, peak at 450 nm; red LED, peak at 630nm) on growth performance of ayu, and antioxidant defense and innate immune responses in spleen for 4, 8 or 12 weeks experiment. White LED experiment was used as the control. Blue LED treatment significantly enhanced body weight and body length after 12 weeks. By contrast, red LED treatment significantly inhibited growth performance of ayu, and decreased the feeding motivation. All LED treatments have no difference in the survival rate during 12 weeks experiment. As compared with white LED condition in the same week, the expression of SOD mRNA was significantly downregulated under the blue LED condition after 4, 8 or 12 weeks. Interestingly, we found a decreased expression of SOD mRNA under red LED condition at the 8-week experiment, and this expression increased at the 12-week. Furthermore, there was an increase in the mRNA levels of CAT and the levels of SOD protein activity for all time under red LED condition. These results show that lighting of red spectral cause the increased oxidative stress of ayu. As for innate immunity, TNF-α mRNA expression increased under blue LED condition after 4, 8 or 12 weeks experiment, however, it significantly increased only at the 12-week under red LED condition. The levels of IL-1β mRNA increased at the 4-week under both blue and red LED condition. LZM mRNA expression was downregulated under blue LED condition after 4 weeks, but it decreased only at the12-week under red LED condition. These findings imply that there is an interaction between antioxidant ability and innate immunity. In summary, changing the lighting of certain spectral in captivity environment can influence the physiological response of ayu, and this study demonstrated a positive effect of blue LED on fish growth performance, antioxidant ability and innate immunity.