Microspectrophotometric analysis of intact chromatophores of the Japanese medaka, Oryzias latipes

To investigate the possible photoprotective role of chromatophores in fish, the absorbances of four types of intact chromatophores in adult and larval Japanese medaka mere analyzed using microspectrophotometric techniques. Th e absorbance spectrum of each chromatophore class was obtained from 300 to 550 nm. The absorbance spectra of intact leucophores, melanophores and xant hophores were very similar to the published absorbance spectra of the isola ted pure pigments contained in each chromatophore type, pteridines, melanin and carotenoids or pteridines, respectively. Based on these absorbance spe ctra, leucophores and melanophores should provide the most ultraviolet CUV) photoprotection to fish since the compounds they contain, pteridines and m elanin, correspondingly, have strong absorbances in the UV region of the sp ectrum. Xanthophores containing carotenoids are not likely to provide much protection to fish from UV-induced damage since carotenoids have low absorb ances in the UV range. Xanthophores containing colored pteridines, however, may provide somewhat greater UV protection to fish, since pteridines absor b more light than carotenoids in the UV portion of the spectrum. The relati ve frequency, coverage and thickness of these two types of xanthophores sho uld determine how much protection xanthophores as a chromatophore type moul d provide against W-induced damage.