Microspectrophotometric Analysis of Intact Chromatophores of the Japanese Medaka, Oryzias latipes

Abstract

To investigate the possible photoprotective role of chromatophores in fish, the absorbances of four types of intact chromatophores in adult and larval Japanese medaka were analyzed using microspectrophotometric techniques. The absorbance spectrum of each chromatophore class was obtained from 300 to 550 nm. The absorbance spectra of intact leucophores, melanophores and xanthophores were very similar to the published absorbance spectra of the isolated pure pigments contained in each chromatophore type, pteridines, melanin and carotenoids or pteridines, respectively. Based on these absorbance spectra, leucophores and melanophores should provide the most ultraviolet (UV) photoprotection to fish since the compounds they contain, pteridines and melanin, correspondingly, have strong absorbances in the UV region of the spectrum. Xanthophores containing carotenoids are not likely to provide much protection to fish from UV-induced damage since carotenoids have low absorbances in the UV range. Xanthophores containing colored pteridines, however, may provide somewhat greater UV protection to fish, since pteridines absorb more light than carotenoids in the UV portion of the spectrum. The relative frequency, coverage and thickness of these two types of xanthophores should determine how much protection xanthophores as a chromatophore type would provide against UV-induced damage.

Precise colocalization of interacting structural and pigmentary elements generates extensive color pattern variation in Phelsumalizards

“…The former are dendritic cells with processes extending through the layer of iridophores for translocation of melanin granules in response to hormones, resulting in darkening of the skin [9,22]. For example, the melanophore processes cover the iridophores in the dorsal skin of P. klemmeri , giving it a light-brown appearance.…”

“…In P. lineata , melanophores are found in combination with red erythrophores in the red-brown regions of the lateral stripes. Hence, in addition to their likely involvement in darkening of the skin, the small melanophores form dark lateral spots/stripes in some Phelsuma geckos, whereas the larger and darker melanophores might protect the deeper layers from harmful UV radiation [22]. However, the homogeneous distribution of these two types of chromatophores in the skin of any color suggests that neither of them substantially contribute to color variation in Phelsuma geckos.…”

Carotenoids in Aquatic Ecosystems and Aquaculture: A Colorful Business with Implications for Human Health

“…30% when zooplankton were exposed to UV radiation in the absence of predator cues (Hylander and Hansson, 2013). In fish, protection from UV radiation is largely provided by pigments other than carotenoids (Armstrong et al, 2000). Integument pigments of fish are stored in a variety of pigment cell types or chromatophores, generally classified into six categories based on their hue: melanophores (black or brown, containing melanin), iridophores (iridescent, containing mainly purines), xanthophores (yellow, containing pteridines, and carotenoids), erythrophores (red containing pteridines and carotenoids), leucophores (white, containing mainly purines), and cyanophores (blue, containing undefined pigments) (Goodwin, 1980;Fujii, 1993Fujii, , 2000Kodric-Brown, 1998).…”

“…Based on pigment absorbance spectra of chromatophores, it is assumed that leucophores and melanophores provide most of the UV photoprotection to fish since pteridines and melanin have strong absorbances in the UV region of the spectrum. Within the xanthophores and erythrophores, pteridines are assumed to offer somewhat greater UV protection to fish than carotenoids, since pteridines absorb more light than carotenoids in the UV portion of the spectrum (Armstrong et al, 2000). MAAs are also taken up by fish, they are accumulated in UV-radiation sensitive tissues such as the eye lenses (Mason et al, 1998).…”

The Biological Mechanisms and Behavioral Functions of Opsin-Based Light Detection by the Skin

“…Circadian rhythms, which oscillate over ∼24 h, allow animals to respond to temporal events in the environment when it is generally most beneficial to do so (e.g., synchronicity of the daily sleep/wake cycle to coincide with the availability of food); however, biological rhythms may be regulated over longer (and shorter) time periods (e.g., circannual Armstrong et al, 2000;Grether et al, 2004).…”