The ambiguity with xanthophore is that they represent not only yellow colored pigment holding cells but also red colored pigment. It has been common practice to name a xanthophore that hold mainly yellow pigments "xanthophore" and a xanthophore that holds mainly red pigments "erythrophore". This can be quite confusing at times, and I personnally chose to use xanthophores (in a herpers language) regardless of the color of the pigments, since it's biologically the same cells. Axanthic, erythristic, anerythristic , in the herpers world commonly reffers to the visible colors. Biologically, xanthophores could actually be termed Pterinophore for they synthesize and hold pterine pigments which can be different reds, orange or yellow. Each of these pigment has a different chemical pathway, but all of them start with GTP-CH1 catalysing GTP into the further steps leading to one or more different pterins (such as sepiapterin or xanthopterin). The chemical pathway of these pterin pigments implicate different enzymes. A mutation inhibiting GTP-CH1 should normally inhibit the production of ALL pterin pigments. Inhibiting another enzyme may only inhibit the production of selected pigments. It may be worth mentioning that xanthopterin has a chemical pathway much different than that of many red pterins.

JF Dery

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