Melanin

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Kazumasa Wakamatsu - One of the best experts on this subject based on the ideXlab platform.

  • Insect cuticular Melanins are distinctly different from those of mammalian epidermal Melanins.
    Pigment Cell & Melanoma Research, 2017
    Co-Authors: Hanine Barek, Manickam Sugumaran, Kazumasa Wakamatsu
    Abstract:

    : Melanin from several insect samples was isolated and subjected to chemical degradation and HPLC analysis for Melanin markers. Quantification of different Melanin markers reveals that insect Melanins are significantly different from that of the mammalian epidermal Melanins. The euMelanin produced in mammals is derived from the oxidative polymerization of both 5,6-dihydroxyindole and 5,6-dihydroxyindole-2-carboxylic acids. The pheoMelanin is formed by the oxidative polymerization of cysteinyldopa. Thus, dopa is the major precursor for both euMelanin and pheoMelanin in mammals. But insect euMelanin appears to be mostly made from 5,6-dihydroxyindole and originates from dopamine. More importantly, our study points out the wide spread occurrence of pheoMelanin in many insect species. In addition, cysteinyldopamine and not cysteinyldopa is the major precursor for insect pheoMelanin. Thus, both euMelanin and pheoMelanin in insects differ from higher animals using dopamine and not dopa as the major precursor.

  • chemical analysis of constitutive pigmentation of human epidermis reveals constant euMelanin to pheoMelanin ratio
    Pigment Cell & Melanoma Research, 2015
    Co-Authors: Sandra Del Bino, Kazumasa Wakamatsu, Yukiko Nakanishi, Philippe Bastien, Francoise Bernerd
    Abstract:

    Summary The skin constitutive pigmentation is given by the amount of Melanin pigment, its relative composition (eu/pheoMelanin) and distribution within the epidermis, and is largely responsible for the sensitivity to UV exposure. Nevertheless, a precise knowledge of Melanins in human skin is lacking. We characterized the Melanin content of human breast skin samples with variable pigmentations rigorously classified through the Individual Typology Angle (ITA) by image analysis, spectrophotometry after solubilization with Soluene-350 and high-performance liquid chromatography (HPLC) after chemical degradation. ITA and total Melanin content were found correlated, ITA and PTCA (degradation product of DHICA Melanin), and TTCA (degradation product of benzothiazole-type pheoMelanin) as well but not 4-AHP (degradation product of benzothiazine-type pheoMelanin). Results revealed that human epidermis comprises approximately 74% of euMelanin and 26% pheoMelanin, regardless of the degree of pigmentation. They also confirm the low content of photoprotective euMelanin among lighter skins thereby explaining the higher sensitivity toward UV exposure.

  • Melanins and melanogenesis: From pigment cells to human health and technological applications
    Pigment Cell and Melanoma Research, 2015
    Co-Authors: Marco D'ischia, Stephane Commo, Ghanem Ghanem, Koike Kenzo, Eduardo Di Mauro, Kazumasa Wakamatsu, Josè Carlos Garcia-borron, Ismael Galvan, Fabio Cicoira, Paul Meredith
    Abstract:

    During the past decade, Melanins and melanogenesis have attracted growing interest for a broad range of biomedical and technological applications. The burst of polydopamine-based multifunctional coatings in materials science is just one example, and the list may be expanded to include Melanin thin films for organic electronics and bioelectronics, drug delivery systems, functional nanoparticles and biointerfaces, sunscreens, environmental remediation devices. Despite considerable advances, applied research on Melanins and melanogenesis is still far from being mature. A closer intersectoral interaction between research centers is essential to raise the interests and increase the awareness of the biomedical, biomaterials science and hi-tech sectors of the manifold opportunities offered by pigment cells and related metabolic pathways. Starting from a survey of biological roles and functions, the present review aims at providing an interdisciplinary perspective of Melanin pigments and related pathway with a view to showing how it is possible to translate current knowledge about physical and chemical properties and control mechanisms into new bioinspired solutions for biomedical, dermocosmetic, and technological applications.

  • sexual dimorphism in Melanin pigmentation feather coloration and its heritability in the barn swallow hirundo rustica
    PLOS ONE, 2013
    Co-Authors: Nicola Saino, Celine Teplitsky, Luca Canova, Diego Rubolini, Roberto Ambrosini, Manuela Caprioli, Maria Romano, Kazumasa Wakamatsu
    Abstract:

    Melanin is the main pigment in animal coloration and considerable variation in the concentrations of the two Melanin forms (pheo- and eumlanin) in pigmented tissues exists among populations and individuals. Melanin-based coloration is receiving increasing attention particularly in socio-sexual communication contexts because the melanocortin system has been hypothesized to provide a mechanistic basis for covariation between coloration and fitness traits. However, with few notable exceptions, little detailed information is available on inter-individual and inter-population variation in Melanin pigmentation and on its environmental, genetic and ontogenetic components. Here, we investigate Melanin-based coloration in an Italian population of a passerine bird, the barn swallow (Hirundo rustica rustica), its sex- and age-related variation, and heritability. The concentrations of eu- and pheoMelanin in the throat (brown) and belly (white-to-brownish) feathers differed between sexes but not according to age. The relative concentration of either Melanin (Pheo:Eu) differed between sexes in throat but not in belly feathers, and the concentrations in males compared to females were larger in belly than in throat feathers. There were weak correlations between the concentrations of Melanins within as well as among plumage regions. Coloration of belly feathers was predicted by the concentration of both Melanins whereas coloration of throat feathers was only predicted by pheoMelanin in females. In addition, Pheo:Eu predicted coloration of throat feathers in females and that of belly feathers in males. Finally, we found high heritability of color of throat feathers. Melanization was found to differ from that recorded in Hirundo rustica rustica from Scotland or from H. r. erythrogaster from North America. Hence, present results show that pigmentation strategies vary in a complex manner according to sex and plumage region, and also among geographical populations, potentially reflecting adaptation to different natural and sexual selection regimes, and that some coloration components seem to be highly heritable.

  • quantitative measures of the effect of the melanocortin 1 receptor on human pigmentary status
    Journal of Investigative Dermatology, 2004
    Co-Authors: Lisa Naysmith, Niamh Flanagan, Tom Ha, Karen Waterston, Yvonne Bisset, Jonathan L. Rees, Kazumasa Wakamatsu
    Abstract:

    Variation in human hair and skin color is the most striking visible aspect of human genetic variation. The only gene known to exert an effect on pigmentary within the normal population is the melanocortin-1 receptor (MC1R). Previous studies have used a Mendelian framework to relate MC1R genotype to phenotype, by measuring pigmentary status using categorical scales. Such approaches are inadequate. We report results using direct measures of hair color using objective colorimetric dimensions and HPLC determined hair Melanins. We have linked MC1R genotype with chemical measures of Melanin quantity and type and objective phenotype measures of color. MC1R genotype was predictive of hair Melanin expressed as the ratio of the log e of euMelanin to pheoMelanin ratio, with a dosage effect evident: MC1R homozygote mean, 1.46; heterozygote, 4.44; and wild type, 5.81 (p

Arturo Casadevall - One of the best experts on this subject based on the ideXlab platform.

  • the structural unit of Melanin in the cell wall of the fungal pathogen cryptococcus neoformans
    Journal of Biological Chemistry, 2019
    Co-Authors: Emma Camacho, Christine Chrissian, Rafael Pradosrosales, Robert N Omeally, Radames J B Cordero, Robert N Cole, Michael J Mccaffery, Ruth E Stark, Arturo Casadevall
    Abstract:

    Melanins are synthesized macromolecules that are found in all biological kingdoms. These pigments have a myriad of roles that range from microbial virulence to key components of the innate immune response in invertebrates. Melanins also exhibit unique properties with potential applications in physics and material sciences, ranging from electrical batteries to novel therapeutics. In the fungi, Melanins, such as euMelanins, are components of the cell wall that provide protection against biotic and abiotic elements. Elucidation of the smallest fungal cell wall-associated Melanin unit that serves as a building block is critical to understand the architecture of these polymers, its interaction with surrounding components, and their functional versatility. In this study, we used isopycnic gradient sedimentation, NMR, EPR, high-resolution microscopy, and proteomics to analyze the Melanin in the cell wall of the human pathogenic fungus Cryptococcus neoformans We observed that Melanin is assembled into the cryptococcal cell wall in spherical structures ∼200 nm in diameter, termed Melanin granules, which are in turn composed of nanospheres ∼30 nm in diameter, termed fungal melanosomes. We noted that Melanin granules are closely associated with proteins that may play critical roles in the fungal melanogenesis and the supramolecular structure of this polymer. Using this structural information, we propose a model for C. neoformans' melanization that is similar to the process used in animal melanization and is consistent with the phylogenetic relatedness of the fungal and animal kingdoms.

  • Melanin triggers antifungal defences
    Nature, 2018
    Co-Authors: Arturo Casadevall
    Abstract:

    Melanins are enigmatic pigments that have many roles, and the Melanin in pathogenic fungi can aid host infection. Identification of a mammalian protein that recognizes Melanin now reveals an antifungal defence pathway. Melanins are enigmatic pigments that have many roles, and the Melanin in pathogenic fungi can aid host infection. Identification of a mammalian protein that recognizes Melanin now reveals an antifungal defence pathway.

  • functions of fungal Melanin beyond virulence
    Fungal Biology Reviews, 2017
    Co-Authors: Radames J B Cordero, Arturo Casadevall
    Abstract:

    Melanins are ancient biological pigments found in all kingdoms of life. In fungi, their role in microbial pathogenesis is well established; however, these complex biomolecules also confer upon fungal microorganisms the faculty to tolerate extreme environments such as the Earth's poles, the International Space Station and places contaminated by toxic metals and ionizing radiation. A remarkable property of Melanin is its capacity to interact with a wide range of electromagnetic radiation frequencies, functioning as a protecting and energy harvesting pigment. Other roles of fungal Melanin include scavenging of free radical, thermo-tolerance, metal ion sequestration, cell development, and mechanical-chemical cellular strength. In this review, we explore the various functions ascribed to this biological pigment in fungi and its remarkable physicochemical properties.

  • physico chemical evaluation of rationally designed Melanins as novel nature inspired radioprotectors
    PLOS ONE, 2009
    Co-Authors: Andrew D Schweitzer, Robertha C Howell, Zewei Jiang, Ruth A Bryan, Gary J Gerfen, Chin Cheng Chen, Sean M Cahill, Arturo Casadevall
    Abstract:

    Background: Melanin, a high-molecular weight pigment that is ubiquitous in nature, protects melanized microorganisms against high doses of ionizing radiation. However, the physics of Melanin interaction with ionizing radiation is unknown. Methodology/Principal Findings: We rationally designed Melanins from either 5-S-cysteinyl-DOPA, L-cysteine/L-DOPA, or LDOPA with diverse structures as shown by elemental analysis and HPLC. Sulfur-containing Melanins had higher predicted attenuation coefficients than non-sulfur-containing Melanins. All synthetic Melanins displayed strong electron paramagnetic resonance (2.14?10 18 , 7.09?10 18 , and 9.05?10 17 spins/g, respectively), with sulfur-containing Melanins demonstrating more complex spectra and higher numbers of stable free radicals. There was no change in the quality or quantity of the stable free radicals after high-dose (30,000 cGy), high-energy ( 137 Cs, 661.6 keV) irradiation, indicating a high degree of radical stability as well as a robust resistance to the ionizing effects of gamma irradiation. The rationally designed Melanins protected mammalian cells against ionizing radiation of different energies. Conclusions/Significance: We propose that due to Melanin’s numerous aromatic oligomers containing multiple p-electron system, a generated Compton recoil electron gradually loses energy while passing through the pigment, until its energy is sufficiently low that it can be trapped by stable free radicals present in the pigment. Controlled dissipation of high-energy recoil electrons by Melanin prevents secondary ionizations and the generation of damaging free radical species.

  • the contribution of Melanin to microbial pathogenesis
    Cellular Microbiology, 2003
    Co-Authors: Joshua D. Nosanchuk, Arturo Casadevall
    Abstract:

    Summary Melanins are enigmatic pigments that are produced by a wide variety of microorganisms including several species of pathogenic bacteria, fungi and helminthes. The study of Melanin is difficult because these pigments defy complete biochemical and structural analysis. Nevertheless, the availability of new reagents in the form of monoclonal antibodies and Melanin-binding peptides, combined with the application of various physical techniques, has provided insights into the process of melanization. Melanization is important in microbial pathogenesis because it has been associated with virulence in many microorganisms. Melanin appears to contribute to virulence by reducing the susceptibility of melanized microbes to host defence mechanisms. However, the interaction of melanized microbes and the host is complex and includes immune responses to Melanin-related antigens. Production of Melanin has also been linked to protection against environmental insults. Interference with melanization is a potential strategy for antimicrobial drug and pesticide development. The process of melanization poses fascinating problems in cell biology and provides a type of pathogenic strategy that is common to highly diverse pathogens.

Paul Meredith - One of the best experts on this subject based on the ideXlab platform.

  • Melanin biopolymers tailoring chemical complexity for materials design
    Angewandte Chemie, 2020
    Co-Authors: Marco Dischia, Paul Meredith, Alessandro Pezzella, Alessandra Napolitano, Markus J Buehler
    Abstract:

    Melanins, a group of dark insoluble pigments found widespread in nature, have become the focus of growing interest in materials science for various biomedical and technological applications, including opto-bioelectronics, nanomedicine and mussel-inspired surface coating. Recent progress in the understanding of Melanin optical, paramagnetic redox, and conductivity properties, including photoconductivity, would point to a revision of the traditional concept of structural disorder in terms of more sophisticated and interrelated levels of chemical complexity which however have never been defined and codified. Herein, we bring to focus the various levels of structural disorder that emerged from spectral and chemical signatures over the past decade. A revised approach to structure-property relationships in terms of intermolecular interactions is also provided that may pave the way towards the rational design of next-generation Melanin-based functional materials.

  • Melanins and melanogenesis: From pigment cells to human health and technological applications
    Pigment Cell and Melanoma Research, 2015
    Co-Authors: Marco D'ischia, Stephane Commo, Ghanem Ghanem, Koike Kenzo, Eduardo Di Mauro, Kazumasa Wakamatsu, Josè Carlos Garcia-borron, Ismael Galvan, Fabio Cicoira, Paul Meredith
    Abstract:

    During the past decade, Melanins and melanogenesis have attracted growing interest for a broad range of biomedical and technological applications. The burst of polydopamine-based multifunctional coatings in materials science is just one example, and the list may be expanded to include Melanin thin films for organic electronics and bioelectronics, drug delivery systems, functional nanoparticles and biointerfaces, sunscreens, environmental remediation devices. Despite considerable advances, applied research on Melanins and melanogenesis is still far from being mature. A closer intersectoral interaction between research centers is essential to raise the interests and increase the awareness of the biomedical, biomaterials science and hi-tech sectors of the manifold opportunities offered by pigment cells and related metabolic pathways. Starting from a survey of biological roles and functions, the present review aims at providing an interdisciplinary perspective of Melanin pigments and related pathway with a view to showing how it is possible to translate current knowledge about physical and chemical properties and control mechanisms into new bioinspired solutions for biomedical, dermocosmetic, and technological applications.

  • role of semiconductivity and ion transport in the electrical conduction of Melanin
    Proceedings of the National Academy of Sciences of the United States of America, 2012
    Co-Authors: A B Mostert, Benjamin J Powell, F L Pratt, Graeme R Hanson, Tadeusz Sarna, Ian R Gentle, Paul Meredith
    Abstract:

    Melanins are pigmentary macromolecules found throughout the biosphere that, in the 1970s, were discovered to conduct electricity and display bistable switching. Since then, it has been widely believed that Melanins are naturally occurring amorphous organic semiconductors. Here, we report electrical conductivity, muon spin relaxation, and electron paramagnetic resonance measurements of Melanin as the environmental humidity is varied. We show that hydration of Melanin shifts the comproportionation equilibrium so as to dope electrons and protons into the system. This equilibrium defines the relative proportions of hydroxyquinone, semiquinone, and quinone species in the macromolecule. As such, the mechanism explains why Melanin at neutral pH only conducts when “wet” and suggests that both carriers play a role in the conductivity. Understanding that Melanin is an electronic-ionic hybrid conductor rather than an amorphous organic semiconductor opens exciting possibilities for bioelectronic applications such as ion-to-electron transduction given its biocompatibility.

Seung Bum Park - One of the best experts on this subject based on the ideXlab platform.

Kuk Youn Ju - One of the best experts on this subject based on the ideXlab platform.

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