Rainbow trout (Oncorhynchus mykiss) is a cold-water fish species with optimal temperature of 12-18 ℃. Temperature stress is a common issue in commercial culture of the Salmonid fish in summer. Both maple trout and steelhead trout are rainbow trout breeding species with good quality. The purpose of this study was to explore the impact of acute temperature stress on antioxidant responses of two kinds of rainbow trout. The juvenile maple trout was diploid, and the juvenile steelhead trout was triploid. The fishes were exposed to four different temperature treatments: 13, 17, 21, and 25 ℃, and hepatic samples were collected at 0, 1, 6, and 12 h. After acute heat stress, the fish were transferred to the tank with optimal temperature (13 ℃) and hepatic samples were collected after 1, 12, 24, and 48 h. The biomarkers, superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), lipid peroxidation (LPO), malondialdehyde (MDA), and heat shock protein 70 kDa (HSP70) were measured. Results showed that the activities of SOD, CAT, and GPx in both maple trout and steelhead trout in 17 ℃ treatment had no significant increase after acute temperature stress. The SOD activities of maple trout and steelhead trout in 21 ℃ treatment significantly increased in response to acute temperature stress, but the SOD activity of maple trout returned to normal during the recovery process. The activities of SOD, CAT, and GPx for both species in 25 ℃ treatment were significantly increased after acute temperature stress, which returned to normal for 24 h recovery. The amount of HSP70 produced by maple trout at 17, 21, and 25 ℃ treatments was significantly higher than that at 13 ℃ treatment, while that of steelhead trout was significantly higher for the 21 and 25 ℃ treatments than that at 13 ℃ treatment. A variety of antioxidant parameters were analyzed by integrated biomarker response (IBR) values. Results showed that the antioxidant response of maple trout was significantly higher than that of steelhead trout in 17 ℃ and 21 ℃ treatments, but significantly lower than steelhead trout in 25 ℃ treatment. Such a result indicated that the antioxidant responses of different ploidy rainbow trouts were different under acute stress at different temperatures.
虹鳟属于冷水性鱼类,其生存的最适温度为12~18 ℃,温度胁迫是虹鳟在夏秋季养殖过程中经常遇到的问题.枫叶鲑和硬头鳟均为品质优良的虹鳟选育种.为探讨急性温度胁迫对两种倍性虹鳟抗氧化响应的影响,本研究选取二倍体枫叶鲑和三倍体硬头鳟幼鱼,分别在13、17、21和25 ℃下进行热应激试验.在达到目标温度后的0、1、6和12 h取样,之后将受试鱼恢复至13 ℃的适宜温度下培养,并在恢复培养的1、12、24和48 h后取样,测定受试鱼肝脏中超氧化物歧化酶(SOD)、过氧化氢酶(CAT)、谷胱甘肽过氧化物酶(GPx)的活性,以及脂质过氧化物(LPO)、丙二醛(MDA)和热激蛋白70(HSP70)含量.结果表明: 枫叶鲑和硬头鳟的3种抗氧化酶活性在17 ℃组没有出现显著升高;21 ℃组枫叶鲑和硬头鳟的SOD活性在热应激期间出现显著升高,但枫叶鲑的SOD活性在恢复过程中恢复到正常水平;25 ℃组枫叶鲑和硬头鳟的SOD、CAT和GPx的活性均显著提高;但在恢复试验进行24 h后,CAT和GPx的活性恢复到正常水平.枫叶鲑在17、21和25 ℃组HSP70的产生量显著高于13 ℃组,而硬头鳟仅在21和25 ℃组HSP70的产生量显著高于13 ℃组.通过整合生物标志物响应指标值对多种抗氧化参数进行分析,发现枫叶鲑在17和21 ℃组急性温度胁迫下的抗氧化响应显著高于硬头鳟,但在25 ℃组硬头鳟的抗氧化响应高于枫叶鲑.这表明不同倍性虹鳟幼鱼在不同温度急性胁迫下的抗氧化响应有所差异.
Keywords: acute temperature stress; antioxidant enzyme; integrate biomarker response indicators; maple trout; steelhead trout.