Gačić Zoran, Milošević Milena, Mićković Branislav, Nikčević Miroslav, Damjanović Ilija
Institute for Multidisciplinary Research, University of Belgrade, Serbia.
Faculty of Biology, University of Belgrade, Serbia.
Comp Biochem Physiol A Mol Integr Physiol. 2015 Jun;184:150-5. doi: 10.1016/j.cbpa.2015.03.002. Epub 2015 Mar 7.
Temperature dependence of electroretinogram (ERG) was investigated in 3 fish species occupying different habitats--dogfish shark (Scyliorhinus canicula), Prussian carp (Carassius gibelio) and European eel (Anguilla anguilla). Acute cooling of the shark isolated eyecup from 23°C down to 6°C induced suppression of the electroretinographic b-wave--a complete degradation of this component was observed at 6°C. On the other hand, photoreceptor component of the ERG, the negative late receptor potential was not affected by cooling. The fact that the suppression of the dogfish shark b-wave at low temperatures was as a rule irreversible testifies about breakdown of neural retinal function at cold temperature extremes. Although in vivo experiments on immobilized Prussian carps have never resulted in complete deterioration of the b-wave at low temperatures, significant suppression of this ERG component by cooling was detected. Suppressing the effect of low temperatures on Prussian carp ERG might be due to the fact that C. gibelio, as well as other cyprinids, can be characterized as a warmwater species preferring temperatures well above cold extremes. The ERG of the eel, the third examined species, exhibited the strongest resistance to extremely low temperatures. During acute cooling of in situ eyecup preparations of migrating silver eels from 30°C down to 2°C the form of ERG became wider, but the amplitude of the b-wave only slightly decreased. High tolerance of eel b-wave to cold extremes shown in our study complies with ecological data confirming eurythermia in migrating silver eels remarkably adapted to cold-water environment as well.
研究了栖息于不同生境的三种鱼类——星鲨（Scyliorhinus canicula）、银鲫（Carassius gibelio）和欧洲鳗鲡（Anguilla anguilla）视网膜电图（ERG）的温度依赖性。将星鲨离体眼杯从23°C急剧冷却至6°C会导致视网膜电图b波受到抑制——在6°C时该成分完全消失。另一方面，ERG的光感受器成分，即负向晚期感受器电位不受冷却影响。低温下星鲨b波的抑制通常不可逆，这证明了在极端低温下神经视网膜功能的破坏。尽管对固定的银鲫进行的体内实验在低温下从未导致b波完全恶化，但通过冷却检测到该ERG成分受到显著抑制。低温对银鲫ERG的抑制作用可能是由于银鲫以及其他鲤科鱼类可被视为喜温水物种，偏好远高于极端低温的温度。作为第三种被研究的物种，鳗鲡的ERG对极低温度表现出最强的抗性。在将洄游银鳗的原位眼杯制剂从30°C急剧冷却至2°C的过程中，ERG的波形变宽，但b波的幅度仅略有下降。我们的研究中显示鳗鲡b波对极端低温具有高耐受性，这与生态数据相符，这些数据证实洄游银鳗具有广温性，也能很好地适应冷水环境。
