Okazaki Toshio
Department of Animal Health Science, Yamazaki Gakuen University, Minami-osawa 4-7-2, Hachiouji, Tokyo 192-0364, Japan.
Zoolog Sci. 2018 Feb;35(1):86-91. doi: 10.2108/zs170091.
I analyzed the association between the reflectance spectra and melanin rod arrangement in barbules of the eyespot of peacock feathers. The reflectance spectra from the yellow-green feather of the eyespot indicated double peaks of 430 and 540 nm. The maximum reflectance spectrum of the blue feather was 480 nm, and that of the dark blue feather was 420 nm. The reflectance spectra from brown feathers indicated double peaks of 490 and 610 nm. Transmission electron microscopic analysis confirmed that melanin rods were arranged fanwise in the outer layer toward the barbule tips. In addition, using polarized light microscope, I attempted to determine whether the turning angles of melanin rods in the barbules reflected different colors. The turning angle of the polarizing axis of the barbules was supported by that of the melanin rods, observed using transmission electron microscopic images. To compare the turning angle of melanin rods in the respective barbules, I calculated the opening width of the fanwise melanin rods by dividing the width of the barbules by the turning angle of the polarizing axis of barbules and obtained a positive correlation between the reflectance spectra and opening width of the fanwise melanin rods. Moreover, the widely spreading reflection from the barbules may occur because of the fanwise melanin rod arrangement.
我分析了孔雀羽毛眼斑羽小枝中反射光谱与黑色素棒排列之间的关联。眼斑黄绿色羽毛的反射光谱显示在430和540纳米处有双峰。蓝色羽毛的最大反射光谱为480纳米，深蓝色羽毛的最大反射光谱为420纳米。棕色羽毛的反射光谱显示在490和610纳米处有双峰。透射电子显微镜分析证实，黑色素棒在外层朝着羽小枝尖端呈扇形排列。此外，我使用偏光显微镜试图确定羽小枝中黑色素棒的转动角度是否反映了不同的颜色。羽小枝偏振轴的转动角度得到了透射电子显微镜图像中观察到的黑色素棒转动角度的支持。为了比较各个羽小枝中黑色素棒的转动角度，我通过将羽小枝的宽度除以羽小枝偏振轴的转动角度来计算扇形黑色素棒的开口宽度，并得出反射光谱与扇形黑色素棒的开口宽度之间存在正相关。此外，羽小枝广泛传播的反射可能是由于黑色素棒呈扇形排列所致。
