Winckler K, Fidhiany L
Institut für Biophysik, Freie Universität Berlin, Germany.
Photochem Photobiol. 1996 Apr;63(4):487-91. doi: 10.1111/j.1751-1097.1996.tb03074.x.
In a previous study we observed that a constant sublethal UVA (320-400 nm) irradiation had a significant effect on the general metabolism in the Convict-cichlid fish (Cichlasoma nigrofasciatum) [Winckler, K. and Fidhiany, L. (1996) J. Photochem. Photobiol. B. Biol. (In press)]. In the present study we show that sublethal UVA irradiation in combination with elevated environmental temperature has a deleterious effect on the same population. The threshold temperature for a sudden increase in mortality of fish receiving an additional sublethal UVA irradiation was 32 degrees C. Prior to the increased mortality, the fish started to avoid the UV light source when the water temperature increased to 31.5 degrees C. Mortality decreased when the temperature declined below 31.5 degrees C. As soon as the temperature changed to normal (adapted) condition (27-29 degrees C) mortality returned to normal levels. In contrast, no changes of fish behavior or mortality were observed at elevated temperature in the nonirradiated reference population. The percentages of fish surviving the high temperature stress were 21.9% for the UVA population and 96.8% for the reference population. The specific oxygen consumption (SOC, average +/- SD) of the survivors from the UVA population during temperature stress was 0.21 +/- 0.05 mg O2 h-1 g body weight (BW)-1, while it was 0.54 +/- 0.11 mg O2 h-1 g BW-1 in the reference population. After the environmental temperature returned below the apparent upper temperature tolerance limit, the oxygen consumption of the UVA population gradually normalized. The SOC measured at different temperature levels--after after the fish passed the temperature stress--showed no significant differences between the UVA population and its reference at 23, 25, 27 and 29 degrees C. However, the SOC at 31 degrees C was significantly (P < 0.05) lower than reference, while at 33 degrees C it was higher (P < 0.10).
在之前的一项研究中，我们观察到持续的亚致死剂量紫外线A（320 - 400纳米）照射对 convict - 丽鱼（Cichlasoma nigrofasciatum）的整体代谢有显著影响[温克勒，K. 和菲迪亚尼，L.（1996年）《光化学与光生物学B：生物学》（即将发表）]。在本研究中，我们表明亚致死剂量紫外线A照射与环境温度升高相结合，对同一鱼群有有害影响。接受额外亚致死剂量紫外线A照射的鱼死亡率突然增加的阈值温度为32摄氏度。在死亡率增加之前，当水温升至31.5摄氏度时，鱼开始避开紫外线光源。当温度降至31.5摄氏度以下时，死亡率下降。一旦温度恢复到正常（适应）状态（27 - 29摄氏度），死亡率就会恢复到正常水平。相比之下，在未照射的对照鱼群中，高温下未观察到鱼的行为或死亡率有变化。经历高温应激后，紫外线A照射组鱼的存活百分比为21.9%，而对照组为96.8%。在温度应激期间，紫外线A照射组存活鱼的特定耗氧量（SOC，平均值±标准差）为0.21±0.05毫克氧气·小时⁻¹·克体重⁻¹，而对照组为0.54±0.11毫克氧气·小时⁻¹·克体重⁻¹。环境温度降至明显的上限温度耐受极限以下后，紫外线A照射组鱼的耗氧量逐渐恢复正常。在鱼经历温度应激后，在不同温度水平下测量的SOC在23、25、27和29摄氏度时，紫外线A照射组与其对照组之间无显著差异。然而，在31摄氏度时，SOC显著低于对照组（P < 0.05），而在33摄氏度时则高于对照组（P < 0.10）。
