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eumelanin

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https://www.readbyqxmd.com/read/29051758/identification-of-yfih-and-the-catalase-cata-as-polyphenol-oxidases-of-aeromonas-media-and-cata-as-a-regulator-of-pigmentation-by-its-peroxyl-radical-scavenging-capacity
#1
Baozhong Chai, Yunqian Qiao, He Wang, Xiaoming Zhang, Jiao Wang, Choushi Wang, Ping Zhou, Xiangdong Chen
Pyomelanin is the major constituent of pigment in melanogenic Aeromonas strains of bacteria. However, eumelanin, synthesized from tyrosine via L-DOPA and polyphenol oxidases (PPOs), may also be present in this genus since L-DOPA is frequently detected in culture fluids of several species. To address this question, we used a deletion mutant of Aeromonas media strain WS, in which pyomelanin synthesis is completely blocked under normal culture conditions. When tyrosine was supplied to the medium, we observed residual melanin accumulation, which we interpret as evidence for existence of the DOPA-melanin pathway...
2017: Frontiers in Microbiology
https://www.readbyqxmd.com/read/29044987/sticky-fingers-at-work-palmitoylation-dependent-mc1r-activation
#2
Jose Carlos Garcia-Borron, Celia Jimenez-Cervantes
The melanocortin-1 receptor (MC1R) is a G protein-coupled receptor (GPCR) positively coupled to the cAMP pathway. MC1R is expressed in melanocytes, where it is critically involved in the cutaneous responses to solar ultraviolet radiation (UVR). The current paradigm posits that UVR-induced DNA damage in skin keratinocytes activates expression of the POMC gene encoding for the precursor of α-melanocyte-stimulating hormone (αMSH). The resulting paracrine release of αMSH activates MC1R in melanocytes and switches the production of melanin pigments from basal pheomelanogenesis to synthesis of eumelanins...
October 17, 2017: Pigment Cell & Melanoma Research
https://www.readbyqxmd.com/read/29039817/replacing-nitrogen-by-sulfur-from-structurally-disordered-eumelanins-to-regioregular-thiomelanin-polymers
#3
Mariagrazia Iacomino, Juan Mancebo-Aracil, Mireia Guardingo, Raquel Martín, Gerardino D'Errico, Marco Perfetti, Paola Manini, Orlando Crescenzi, Félix Busqué, Alessandra Napolitano, Marco d'Ischia, Josep Sedó, Daniel Ruiz-Molina
The oxidative polymerization of 5,6-dihydroxybenzothiophene (DHBT), the sulfur analog of the key eumelanin building block 5,6-dihydroxyindole (DHI), was investigated to probe the role of nitrogen in eumelanin build-up and properties. Unlike DHI, which gives a typical black insoluble eumelanin polymer on oxidation, DHBT is converted to a grayish amorphous solid (referred to as thiomelanin) with visible absorption and electron paramagnetic resonance properties different from those of DHI melanin. Mass spectrometry experiments revealed gradational mixtures of oligomers up to the decamer level...
October 17, 2017: International Journal of Molecular Sciences
https://www.readbyqxmd.com/read/29022703/probing-the-eumelanin-silica-interface-in-chemically-engineered-bulk-hybrid-nanoparticles-for-targeted-subcellular-antioxidant-protection
#4
Brigida Silvestri, Giuseppe Vitiello, Giuseppina Luciani, Vincenzo Calcagno, Aniello Costantini, Maria Gallo, Silvia Parisi, Simona Paladino, Mariagrazia Iacomino, Gerardino D'Errico, Maria Federica Caso, Alessandro Pezzella, Marco d'Ischia
We disclose herein the first example of stable monodispersed hybrid nanoparticles (termed MelaSil-NPs) made up of eumelanin biopolymer intimately integrated into a silica nanoscaffold matrix and endowed with high antioxidant and cytoprotective effects associated with a specific subcellular localization. MelaSil-NPs have been fabricated by an optimized sol-gel methodology involving ammonia-induced oxidative polymerization of a covalent conjugate of the eumelanin building block 5,6-dihydroxyindole-2-carboxylic acid (DHICA) with 3-aminopropyltriethoxysilanes (APTS)...
October 12, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28937213/structural-basis-of-polydopamine-film-formation-probing-5-6-dihydroxyindole-based-eumelanin-type-units-and-the-porphyrin-issue
#5
Maria L Alfieri, Raffaella Micillo, Lucia Panzella, Orlando Crescenzi, Stefano L Oscurato, Pasqualino Maddalena, Alessandra Napolitano, Vincent Ball, Marco d'Ischia
The role of 5,6-dihydroxyindole (DHI)-based oligomers, including porphyrin-like tetramers, in polydopamine (PDA) film formation was addressed by a comparative structural investigation against model polymers from DHI and its 2,7'-dimer. MALDI-MS data showed that (a) PDA is structurally different from DHI melanin and does not contain species compatible with DHI-based oligomers as primary building blocks; (b) PDA films and precipitate display a single main peak at m/z 402 in common; (c) no species matching the range of m/z values expected for cyclic porphyrin-type tetramers was detected in DHI melanin produced in the presence or in the absence of folic acid (FA) as templating agent, nor by oxidation of the 2,7'-dimer of DHI as putative precursor...
September 29, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28878140/the-supramolecular-buildup-of-eumelanin-structures-mechanisms-controllability
#6
REVIEW
Anne Büngeler, Benjamin Hämisch, Oliver I Strube
Research on the supramolecular buildup of eumelanin has gained high momentum in the last years. Several new aspects regarding the involved structures and mechanisms have been established, which has led to a better understanding of the entire process. This review intends to provide a clearly laid-out summary of previous and new findings regarding structures, mechanisms, and controllability. With respect to materials applications, the aspect of controllability is of supreme importance. A focus of this review is therefore set on a novel method with high potential for specific synthesis of various, isolated particle morphologies...
September 6, 2017: International Journal of Molecular Sciences
https://www.readbyqxmd.com/read/28878021/ck1%C3%AE-ablation-in-keratinocytes-induces-p53-dependent-sunburn-protective-skin-hyperpigmentation
#7
Chung-Hsing Chang, Che-Jung Kuo, Takamichi Ito, Yu-Ya Su, Si-Tse Jiang, Min-Hsi Chiu, Yi-Hsiung Lin, Andrea Nist, Marco Mernberger, Thorsten Stiewe, Shosuke Ito, Kazumasa Wakamatsu, Yi-An Hsueh, Sheau-Yann Shieh, Irit Snir-Alkalay, Yinon Ben-Neriah
Casein kinase 1α (CK1α), a component of the β-catenin destruction complex, is a critical regulator of Wnt signaling; its ablation induces both Wnt and p53 activation. To characterize the role of CK1α (encoded by Csnk1a1) in skin physiology, we crossed mice harboring floxed Csnk1a1 with mice expressing K14-Cre-ER(T2) to generate mice in which tamoxifen induces the deletion of Csnk1a1 exclusively in keratinocytes [single-knockout (SKO) mice]. As expected, CK1α loss was accompanied by β-catenin and p53 stabilization, with the preferential induction of p53 target genes, but phenotypically most striking was hyperpigmentation of the skin, importantly without tumorigenesis, for at least 9 mo after Csnk1a1 ablation...
September 19, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/28873228/photodegradation-of-eumelanin-and-pheomelanin-and-its-pathophysiological-implications
#8
Shosuke Ito, Kazumasa Wakamatsu, Tadeusz Sarna
Eumelanin is photoprotective for pigmented tissues while pheomelanin is phototoxic. In this review, we summarize current understanding of how eumelanin and pheomelanin structures are modified by ultraviolet A (UVA) and also by visible light and how reactive oxygen species participate in those processes. Alkaline hydrogen peroxide oxidation was employed to characterize eumelanin and benzothiazole-type pheomelanin, giving pyrrole-2,3,5-tricarboxylic acid (PTCA) and thiazole-2,4,5-tricarboxylic acid (TTCA), respectively...
September 5, 2017: Photochemistry and Photobiology
https://www.readbyqxmd.com/read/28753933/deciphering-molecular-mechanisms-of-interface-buildup-and-stability-in-porous-si-eumelanin-hybrids
#9
Elisa Pinna, Claudio Melis, Aleandro Antidormi, Roberto Cardia, Elisa Sechi, Giancarlo Cappellini, Marco d'Ischia, Luciano Colombo, Guido Mula
Porous Si/eumelanin hybrids are a novel class of organic-inorganic hybrid materials that hold considerable promise for photovoltaic applications. Current progress toward device setup is, however, hindered by photocurrent stability issues, which require a detailed understanding of the mechanisms underlying the buildup and consolidation of the eumelanin-silicon interface. Herein we report an integrated experimental and computational study aimed at probing interface stability via surface modification and eumelanin manipulation, and at modeling the organic-inorganic interface via formation of a 5,6-dihydroxyindole (DHI) tetramer and its adhesion to silicon...
July 19, 2017: International Journal of Molecular Sciences
https://www.readbyqxmd.com/read/28753659/melanic-variation-underlies-aposematic-color-variation-in-two-hymenopteran-mimicry-systems
#10
Heather M Hines, Paige Witkowski, Joseph S Wilson, Kazumasa Wakamatsu
The stinging hymenopteran velvet ants (Mutillidae) and bumble bees (Apidae: Bombus spp.) have both undergone extensive diversification in aposematic color patterns, including yellow-red hues and contrasting dark-light body coloration, as a result of Müllerian mimicry. Understanding the genetic and developmental mechanisms underlying shifts in these mimetic colors requires characterization of their pigmentation. In this study, a combination of solubility, spectrophotometry, and melanin degradation analysis are applied to several color forms and species of these lineages to determine that orange-red colors in both lineages are comprised of primarily dopamine-derived pheomelanins...
2017: PloS One
https://www.readbyqxmd.com/read/28746990/identification-of-a-gene-involved-in-the-negative-regulation-of-pyomelanin-production-in-ralstonia-solanacearum
#11
Shabir Ahmad, Seung Yeup Lee, Raees Khan, Hyun Gi Kong, Geun Ju Son, Nazish Roy, Kihyuck Choi, Seon-Woo Lee
Ralstonia solanacearum causes bacterial wilt in a wide variety of host plant species and produces a melanin-like blackish-brown pigment in stationary phase when grown in minimal medium supplemented with tyrosine. To study melanin production regulation in R. solanacearum, five mutants exhibiting overproduction of melanin-like pigments were selected from a transposon (Tn) insertion mutant library of R. solanacearum SL341. Most of the mutants, except one (SL341T), were not complemented by the original gene or overproduced melanins...
September 28, 2017: Journal of Microbiology and Biotechnology
https://www.readbyqxmd.com/read/28726920/pheomelanin-molecular-vibration-is-associated-with-mitochondrial-ros-production-in-melanocytes-and-systemic-oxidative-stress-and-damage
#12
Ismael Galván, Alberto Jorge, María García-Gil
Vibrations in covalent bonds affect electron delocalization within molecules, as reported in polymers. If synthesized by living cells, the electron delocalization of polymers affects the stabilization of cellular free radicals, but biomolecular vibration has never been considered a potential source of cytotoxicity. Here we show that the vibrational characteristics of natural pheomelanin and eumelanin contribute to feather color expression in four poultry breeds with different melanin-based pigmentation patterns, but only the vibrational characteristics of pheomelanin are related to the production of reactive oxygen species (ROS) in the mitochondria of melanocytes and to systemic levels of cellular oxidative stress and damage...
September 18, 2017: Integrative Biology: Quantitative Biosciences From Nano to Macro
https://www.readbyqxmd.com/read/28677151/getting-a-tan-without-getting-sik
#13
John A D'Orazio
No abstract text is available yet for this article.
September 2017: Pigment Cell & Melanoma Research
https://www.readbyqxmd.com/read/28639791/insight-into-the-final-step-of-the-supramolecular-buildup-of-eumelanin
#14
Anne Büngeler, Benjamin Hämisch, Klaus Huber, Wolfgang Bremser, Oliver I Strube
The final step in the supramolecular buildup of eumelanin particles is investigated regarding the involved species and mechanism. Time-resolved in situ light scattering and scanning electron microscopy reveal an aggregation of particles with a narrow size distribution around 40 nm, previously only observed as substructures. These form larger particles with again very uniform size and diameters around 200 nm. Aggregation of each single particle takes only a few minutes to complete, whereas the entire process goes on for at least 3 h, partly due to the kinetics of the precursors...
June 30, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
https://www.readbyqxmd.com/read/28639704/genome-wide-association-analysis-identifies-potential-regulatory-genes-for-eumelanin-pigmentation-in-chicken-plumage
#15
L Yang, X Du, S Wei, L Gu, N Li, Y Gong, S Li
Plumage color in chicken is determined by the proportion of eumelanin and pheomelanin pigmentation. As the main ingredient in plumage melanin, eumelanin plays a key role in the dark black, brown and grey coloration. However, very few studies have been performed to identify the related genes and mutations on a genome-wide scale. Herein, a resource family consisting of one backcross population and two F2 cross populations between a black roster and Yukou Brown I parent stockbreed was constructed for identification of genes related to eumelanin pigmentation...
October 2017: Animal Genetics
https://www.readbyqxmd.com/read/28614705/a-uv-independent-topical-small-molecule-approach-for-melanin-production-in-human-skin
#16
Nisma Mujahid, Yanke Liang, Ryo Murakami, Hwan Geun Choi, Allison S Dobry, Jinhua Wang, Yusuke Suita, Qing Yu Weng, Jennifer Allouche, Lajos V Kemeny, Andrea L Hermann, Elisabeth M Roider, Nathanael S Gray, David E Fisher
The presence of dark melanin (eumelanin) within human epidermis represents one of the strongest predictors of low skin cancer risk. Topical rescue of eumelanin synthesis, previously achieved in "redhaired" Mc1r-deficient mice, demonstrated significant protection against UV damage. However, application of a topical strategy for human skin pigmentation has not been achieved, largely due to the greater barrier function of human epidermis. Salt-inducible kinase (SIK) has been demonstrated to regulate MITF, the master regulator of pigment gene expression, through its effects on CRTC and CREB activity...
June 13, 2017: Cell Reports
https://www.readbyqxmd.com/read/28570058/elucidating-the-photoprotection-mechanism-of-eumelanin-monomers
#17
Paulami Ghosh, Debashree Ghosh
Eumelanin, the functional polymer in human skin, forms a heterogeneous layered structure intrinsic to its broadband monotonic spectra. The inherent structural heterogeneity of eumelanin makes the photoprocesses very complex and diverse in nature. Due to this diversity, a complete mechanistic picture of these photoprocesses, essential to understanding the photoprotective properties, has been missing to date. In this study, we recreate the potential energy surfaces of the low-lying excited states of the multiple monomeric forms of eumelanin constituents that play a prominent role in either photoprotection or photodamage pathways...
June 9, 2017: Journal of Physical Chemistry. B
https://www.readbyqxmd.com/read/28566355/spiders-have-rich-pigmentary-and-structural-colour-palettes
#18
Bor-Kai Hsiung, Nicholas M Justyn, Todd A Blackledge, Matthew D Shawkey
Elucidating the mechanisms of colour production in organisms is important for understanding how selection acts upon a variety of behaviours. Spiders provide many spectacular examples of colours used in courtship, predation, defence and thermoregulation, but are thought to lack many types of pigments common in other animals. Ommochromes, bilins and eumelanin have been identified in spiders, but not carotenoids or melanosomes. Here, we combined optical microscopy, refractive index matching, confocal Raman microspectroscopy and electron microscopy to investigate the basis of several types of colourful patches in spiders...
June 1, 2017: Journal of Experimental Biology
https://www.readbyqxmd.com/read/28560094/eumelanin-and-pheomelanin-are-predominant-pigments-in-bumblebee-apidae-bombus-pubescence
#19
Carlo Polidori, Alberto Jorge, Concepción Ornosa
BACKGROUND: Bumblebees (Hymenoptera: Apidae: Bombus) are well known for their important inter- and intra-specific variation in hair (or pubescence) color patterns, but the chemical nature of the pigments associated with these patterns is not fully understood. For example, though melanization is believed to provide darker colors, it still unknown which types of melanin are responsible for each color, and no conclusive data are available for the lighter colors, including white. METHODS: By using dispersive Raman spectroscopy analysis on 12 species/subspecies of bumblebees from seven subgenera, we tested the hypothesis that eumelanin and pheomelanin, the two main melanin types occurring in animals, are largely responsible for bumblebee pubescence coloration...
2017: PeerJ
https://www.readbyqxmd.com/read/28533464/the-colours-of-humanity-the-evolution-of-pigmentation-in-the-human-lineage
#20
REVIEW
Nina G Jablonski, George Chaplin
Humans are a colourful species of primate, with human skin, hair and eye coloration having been influenced by a great variety of evolutionary forces throughout prehistory. Functionally naked skin has been the physical interface between the physical environment and the human body for most of the history of the genus Homo, and hence skin coloration has been under intense natural selection. From an original condition of protective, dark, eumelanin-enriched coloration in early tropical-dwelling Homo and Homo sapiens, loss of melanin pigmentation occurred under natural selection as Homo sapiens dispersed into non-tropical latitudes of Africa and Eurasia...
July 5, 2017: Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences
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