FINE STRUCTURAL OBSERVATIONS RELATING TO THE PRODUCTION OF COLOR BY THE IRIDOPHORES OF A LIZARD, <i>ANOLIS CAROLINENSIS </i>

Rohrlich, Susannah T.; Porter, Keith R.

doi:10.1083/jcb.53.1.38

Cited by 61 publications

(45 citation statements)

References 22 publications

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“…Although chromatophores have been described in some squamates [8,9,13-16], and their melanin pathway has been associated with adaptive color variation [17,18], few data are available on the mechanisms that generate extensive variation in non-melanic pigments and structural colors in this lineage. The presence of such a variety of colors in squamates makes them appropriate models for investigating the essentially unknown genetic, developmental, and physical mechanisms generating a diversity of phenotypes through interactions between different types of chromatophores.…”

Section: Introductionmentioning

confidence: 99%

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

et al. 2013

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BackgroundColor traits in animals play crucial roles in thermoregulation, photoprotection, camouflage, and visual communication, and are amenable to objective quantification and modeling. However, the extensive variation in non-melanic pigments and structural colors in squamate reptiles has been largely disregarded. Here, we used an integrated approach to investigate the morphological basis and physical mechanisms generating variation in color traits in tropical day geckos of the genus Phelsuma.ResultsCombining histology, optics, mass spectrometry, and UV and Raman spectroscopy, we found that the extensive variation in color patterns within and among Phelsuma species is generated by complex interactions between, on the one hand, chromatophores containing yellow/red pteridine pigments and, on the other hand, iridophores producing structural color by constructive interference of light with guanine nanocrystals. More specifically, we show that 1) the hue of the vivid dorsolateral skin is modulated both by variation in geometry of structural, highly ordered narrowband reflectors, and by the presence of yellow pigments, and 2) that the reflectivity of the white belly and of dorsolateral pigmentary red marks, is increased by underlying structural disorganized broadband reflectors. Most importantly, these interactions require precise colocalization of yellow and red chromatophores with different types of iridophores, characterized by ordered and disordered nanocrystals, respectively. We validated these results through numerical simulations combining pigmentary components with a multilayer interferential optical model. Finally, we show that melanophores form dark lateral patterns but do not significantly contribute to variation in blue/green or red coloration, and that changes in the pH or redox state of pigments provide yet another source of color variation in squamates.ConclusionsPrecisely colocalized interacting pigmentary and structural elements generate extensive variation in lizard color patterns. Our results indicate the need to identify the developmental mechanisms responsible for the control of the size, shape, and orientation of nanocrystals, and the superposition of specific chromatophore types. This study opens up new perspectives on Phelsuma lizards as models in evolutionary developmental biology.

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Section: Introductionmentioning

confidence: 99%

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

et al. 2013

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“…Iridophores are unique color-generating cells in that they produce color structurally, rather than by containing specific-colored pigments. A variety of physical mechanisms have been implicated in iridophores of widely differing ultrastructure, including "yndall scattering (Kawaguti and Kamishima, 1964), diffraction (Cloney and Brocco, 1983) and thin-layer interference (Denton and Land, 1971;Rohrlich and Porter, 1972). Iridophores found in vertebrates generally contain purine crystals.…”

Section: Introductionmentioning

confidence: 99%

A Transmission Electron Microscopic (TEM) Method for Determining Structural Colors Reflected by Lizard Iridophores

Morrison

1995

Pigment Cell Research

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Iridescent tissue colors are thought to be produced by iridophores through the optical phenomenon of thin-layer interference. Land and others have shown that structural features, predominantly reflecting platelet width and the cytoplasmic spacing between layers of platelets, determine the wavelength of light maximally reflected by this mechanism in iridophores. Some researchers have used interference microscopy to estimate these structural parameters, but the most direct measurement technique should be transmission electron microscopy (TEM). Transmission electron microscopy (TEM) has associated processing artifacts (particularly cytoplasmic shrinkage) that preclude direct measurement of ultrastructure, but if a number of assumptions are made, reflected wavelengths can be predicted. A thin-layer interference model and its associated assumptions were tested using TEM measurements of iridophores from several brightly colored tissues of each of three lizards (Sceloporus jarrovi, S. undulatus erythrocheilus, and S. magister). In all the instances examined when the contribution of the pigments present were accounted for, tissue color corresponded with predicted iridophore reflectances from the model. Finally, if the model and its assumptions are assumed to be correct, the amount of iridophore cytoplasmic shrinkage as a result of TEM processing can be calculated.

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“…Xanthophore pigmentation acts concertedly with RPs of underlying iridophores (Bagnara and Hadley 1973;Fox 1976;Grether et al 2004). Two models that have traditionally related observed light reflectance to RPs include Tyndall scattering and thin-layer interference (Rohrlich and Porter 1972;Fox 1976;Bagnara et al 2007). Based upon RP orientations in Anolis carolinensis, Rohrlich and Porter (1972) proposed that thin-layer interference, rather than Tyndall scattering, might be the more-likely model for iridophore reflectance in squamates.…”

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confidence: 99%

“…Two models that have traditionally related observed light reflectance to RPs include Tyndall scattering and thin-layer interference (Rohrlich and Porter 1972;Fox 1976;Bagnara et al 2007). Based upon RP orientations in Anolis carolinensis, Rohrlich and Porter (1972) proposed that thin-layer interference, rather than Tyndall scattering, might be the more-likely model for iridophore reflectance in squamates. Using a thin-layer interference model, Morrison (1995) found that the iridophores of three different sceloporines (Sceloporus undulatus erythrocheilus, Sceloporus jarrovi, and Sceloporus magister) were capable of monochromatic reflectance.…”

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confidence: 99%

The Cellular Basis of Polymorphic Coloration in Common Side-Blotched Lizards,Uta stansburiana

et al. 2015

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Diurnal lizards are useful model organisms for the study of color polymorphisms. The cellular basis of nonavian reptilian coloration and dermal chromatophores, as well as the different pigments contained therein, is relatively well understood. Nonetheless, specific predictions cannot be made for the biochemical chromatophore constituents of individual species a priori. Despite well-documented associations between throat coloration and behavioral, physiological, and life history traits, the cellular basis of throat coloration in polymorphic Common Side-Blotched Lizards, Uta stansburiana, has never been studied. We used a combination of chromatographic techniques in conjunction with transmission electron microscopy and a thin-layer reflectance model to determine the cellular basis of polymorphic coloration in U. stansburiana. We found that different morphs express coloration through varying spatial arrangements of dietary xanthophylls (lutein and zeaxanthin), differential synthesis of drosopterins, differential melanin synthesis, and morph-specific iridophore reflecting platelets. Our results indicate that chromatic variations in this polymorphism cannot be attributed to alternative xanthophore pigmentation or structural reflectance alone. Instead, the chromatophores of U. stansburiana are multicomponent color signals.

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FINE STRUCTURAL OBSERVATIONS RELATING TO THE PRODUCTION OF COLOR BY THE IRIDOPHORES OF A LIZARD, ANOLIS CAROLINENSIS

Cited by 61 publications

References 22 publications

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

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

A Transmission Electron Microscopic (TEM) Method for Determining Structural Colors Reflected by Lizard Iridophores

The Cellular Basis of Polymorphic Coloration in Common Side-Blotched Lizards,Uta stansburiana

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