Pheomelanin in the skin of Hymenochirus boettgeri (Amphibia: Anura: Pipidae)

Abstract

Additional Supporting Information may be found in the online version of this article: Figure S1. Peptide-blocking of anti-OT antibody staining. Figure S2. Structure of prepro-OT mRNA. Figure S3. Quantitative PCR analysis of OT mRNA level in keratinocytes. University, ul. Gronostajowa 7, Poland, Abstract: Pheomelanin is supposed to be the first type of melanin found in vertebrates, in contrast to the main typeeumelanin. Our study aimed at detecting pheomelanin in the skin of Hymenochirus boettgerii. We employed electron paramagnetic resonance (EPR) spectroscopy, and transmission electron microscopy (TEM), supplemented with standard histology and immunochemistry. We identified pheomelanin in the dorsal skin of adult frogs (not only in the dermis, but also in the epidermis) and in the dorsal tadpole. Our work identifies Hymenochirus boettgerii as a model in the basic study on the mechanism, evolution and role of melanogenesis in animals, including human.

Chemical, experimental, and morphological evidence for diagenetically altered melanin in exceptionally preserved fossils

“…Phaeomelanin was thought to be restricted to warm-blooded animals, presumably evolving convergently for metabolic reasons (40). However, it appears that phaeomelanin is actually more widespread in ectothermic organisms than previously thought (14)(15)(16)(17). As proposed recently (20), the more pure melanins in mammals and birds could reflect the marked shift in external integument with the evolution of hair and feathers for insulation in these warm-blooded animals rather than physiology (13).…”

“…In extant mammals and birds, eumelanosomes are oblong, with a higher aspect ratio than phaeomelanosomes, which are smaller and more spherical (3,13). It is not clear whether other amniotes or fishes produce morphologically distinct melanosomes, but chemical evidence distinguishes pure eumelanin and phaeomelanin in turtles (14), and phaeomelanin has been tentatively reported in frogs (15), fish (16), and chitons (Mollusca) (17). Melanosome morphology currently serves as the primary basis for interpretations of fossil feather color, as it correlates with several distinct melaninbased colors and iridescence in modern birds (1,3,4).…”

Bacteria or melanosomes? A geochemical analysis of micro-bodies on a tadpole from the Oligocene Enspel Formation of Germany

“…1h). The presence of the pigment pheomelanin, contained within pheomelanosomes, has recently been demonstrated in amphibian skin (Wolnicka-Glubisz et al 2012); however this does not Fig. 6 XANES spectra of zinc standards, blonde human hair and FS003b tadpole at the zinc K edge shown as the normalized absorption (a) and the first derivative (b).…”

Application of Electron Paramagnetic Resonance Spectroscopy to Examine Free Radicals in Melanin Polymers and the Human Melanoma Malignum Cells

“…Comparison of the lineshape of these EPR spectra indicates that eumelanin reveals the simple single line (Figure 2a) and EPR line of pheomelanin reveals the complex shape with the unresolved hyperine structure (Figure 2b). The lineshapes of the EPR spectra of DOPAmelanin [17-19, 26, 34-37] and pheomelanin [22,31,[38][39][40] were presented in a lot of papers. EPR spectra were measured for free radicals in melanotic tumor cells [44][45][46][47][48][49][50][51][52].…”

“…This absorption is the base of electron paramagnetic resonance (EPR) spectroscopy [41][42][43]. Free radicals in eumelanin [17-19, 26, 40] and pheomelanin [22,31,[38][39][40] are responsible for the EPR spectra, which difer in the shape. Typical EPR spectra of the model eumelanin DOPA-melanin and pheomelanin are shown in Figure 2.…”