Makino M, Nagai K, Suzuki T
Vision Res. 1983;23(2):199-204. doi: 10.1016/0042-6989(83)90143-8.
Visual pigment composition was determined by HPLC analysis over a one-year period in the adult bullfrog (Rana catesbeiana). In Japan, the vitamin A2-based pigment was only 5% of the total visual pigment from the middle of July to October. The vitamin A2-based pigment increased in November and reached a maximum of 32-36% between January and June. This seasonal variation may relate to the average of outdoor temperature rather than the daylight hours. The amount of vitamin A2-based pigment began to increase when the average temperature became lower than 20 degrees C and it decreased rapidly as the average temperature was higher than 20 degrees C.
在为期一年的时间里，通过高效液相色谱分析测定了成年牛蛙（牛蛙）的视觉色素组成。在日本，从7月中旬到10月，基于维生素A2的色素仅占视觉色素总量的5%。基于维生素A2的色素在11月增加，并在1月至6月间达到最高值32%-36%。这种季节性变化可能与室外平均温度有关，而非日照时长。当平均温度低于20摄氏度时，基于维生素A2的色素量开始增加，而当平均温度高于20摄氏度时，其迅速减少。
