Vitamin A2-based visual pigments in fully terrestrial vertebrates
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Updated: Oct 13, 2026

Measurement of Carotenoids in Perifovea using the Macular Pigment Reflectometer
Published on: January 29, 2020
I Provencio1, E R Loew, R G Foster
1Department of Biology, University of Virginia, Charlottesville 22901.
Abstract:
As part of a broad study of the ocular and extraocular photoreceptors of reptiles, we have used high performance liquid chromatography (HPLC) to identify the retinoids present in whole eye extracts of the arboreal lizard Anolis carolinensis and the non-arboreal ruin lizard Podarcis sicula. Unexpectedly, only vitamin A2-derived chromophore was detected in Anolis, while a mixture of vitamin A1- and vitamin A2-derived chromophores was detected in Podarcis. These are the first examples of fully terrestrial vertebrates using vitamin A2-derived chromophore for visual pigment generation. Furthermore, microspectrophotometric (MSP) data for Anolis show a class of photoreceptor having a visual pigment with maximum absorbance at about 625 nm, some 40 nm further into the red than has been found in any terrestrial vertebrate examined to date.
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