Stressful daylight: Differences in diel rhythmicity between albino and pigmented fish

In laboratory experiments, variously colored strains of animals, including those with albino phenotypes, are commonly used. The melanocortin theory suggests, however, that coloration phenotypes alter animal physiology and behavior. Animals with the albino phenotype show photoreceptor degradation associated with lowered visual accuracy, escape reactions, etc., presumably accompanied by prevailing nocturnal activity and lowered aggressiveness. This assumption was tested in small groups of albino and pigmented European catfish, Silurus glanis, during the circadian cycle. The frequency of agonistic interactions was observed during mutual contests for shelters, and subsequently, blood plasma, brain, gill, and liver samples were collected to evaluate stress parameters. In an experimental arena with shelters, the light/dark rhythmicity of locomotor activity and aggressiveness of the two phenotypes were comparable; the acrophase was observed at night, and a lower peak was observed at dawn. In a...

实验室实验中，常使用不同颜色品系的动物，包括具有白化表型（albino phenotype）的个体。然而，黑皮质素理论（melanocortin theory）认为，体色表型会改变动物的生理机能与行为。具有白化表型的动物表现出光感受器（photoreceptor）退化，这与视觉精度下降、逃逸反应异常等相关，推测还伴随以夜行性活动为主及攻击性降低的特征。本研究在昼夜节律（circadian cycle）周期内，以小型群体的白化型和有色型欧洲鲶鱼（Silurus glanis）为对象验证了这一假设。观察了两者在争夺庇护所时的攻击性行为（agonistic interactions）频率；随后采集血浆、脑、鳃及肝脏样本以评估应激参数（stress parameters）。在设有庇护所的实验场地中，两种表型的运动活性及攻击性在光暗节律下具有可比性；其活动高峰（acrophase）出现于夜间，黎明时则有一个较低峰。在...