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https://www.readbyqxmd.com/read/28510134/paramagnetics-melanin-and-mn-2-in-black-soldier-fly-hermetia-illucens
#1
N A Ushakova, A E Dontsov, A I Bastrakov, N Y Garmash, D S Pavlov
Larva, prepupa (last instar larva), pupa, and an empty shell of pupa after hatching of the black soldier fly Hermetia illucens contain eumelanin, an active synthesis of which is observed at the prepupal stage, which is probably due to the release of prepupa from the feed substrate thickness to the open space for pupation. It was shown for the first time that prepupa contains high quantities of the magnetically active form of manganese Mn(2+). This fact indicates that Mn(2+) stimulates the copper-containing tyrosinase-the key enzyme in the synthesis of melanin in the period of migration and adaptation of the insect to the solar radiation...
March 2017: Doklady. Biochemistry and Biophysics
https://www.readbyqxmd.com/read/28457648/circulating-testosterone-and-its-feather-gene-expression-of-receptors-and-metabolic-enzymes-in-relation-to-melanin-based-coloration-in-the-barn-owl
#2
Paul Béziers, Anne-Lyse Ducrest, Céline Simon, Alexandre Roulin
Knowledge of how and why secondary sexual characters are associated with sex hormones is important to understand their signalling function. Such a link can occur if testosterone participates in the elaboration of sex-traits, if the display of an ornament triggers behavioural response in conspecifics that induce a rise in testosterone or if genes implicated in the elaboration of a sex-trait pleiotropically regulate testosterone physiology. To evaluate the origin of the covariation between melanism and testosterone we measured this hormone and the expression of enzymes involved in its metabolism in feathers of barn owl (Tyto alba) nestlings at the time of melanogenesis and in adults outside the period of melanogenesis...
April 27, 2017: General and Comparative Endocrinology
https://www.readbyqxmd.com/read/28451292/polydopamine-and-eumelanin-molecular-structures-investigated-with-ab-initio-calculations
#3
Chun-Teh Chen, Francisco J Martin-Martinez, Gang Seob Jung, Markus J Buehler
A set of computational methods that contains a brute-force algorithmic generation of chemical isomers, molecular dynamics (MD) simulations, and density functional theory (DFT) calculations is reported and applied to investigate nearly 3000 probable molecular structures of polydopamine (PDA) and eumelanin. All probable early-polymerized 5,6-dihydroxyindole (DHI) oligomers, ranging from dimers to tetramers, have been systematically analyzed to find the most stable geometry connections as well as to propose a set of molecular models that represents the chemically diverse nature of PDA and eumelanin...
February 1, 2017: Chemical Science
https://www.readbyqxmd.com/read/28415485/antimicrobial-activity-of-eumelanin-based-hybrids-the-role-of-tio2-in-modulating-the-structure-and-biological-performance
#4
Giuseppe Vitiello, Alessandro Pezzella, Anna Zanfardino, Brigida Silvestri, Paola Giudicianni, Aniello Costantini, Mario Varcamonti, Francesco Branda, Giuseppina Luciani
Eco-friendly hybrid Eumelanin-TiO2 nanostructures, recently obtained through in situ methodology based on hydrothermal route, have shown a striking antimicrobial activity, after exposure to oxidative environment, even under visible light induction condition. Nevertheless, the role of each component in defining the efficacy of these biological properties is far from being clearly defined. Furthermore, the effect of oxidative step on hybrids structure has not yet addressed. This study aims at elucidating the role of the ratio between eumelanin precursor, 5,6-dihydroxyindole-2-carboxylic acid (DHICA), and TiO2, for its polymerization in defining morphology and structural organization of TiO2-melanin nanostructures...
June 1, 2017: Materials Science & Engineering. C, Materials for Biological Applications
https://www.readbyqxmd.com/read/28378380/re-evaluation-of-insect-melanogenesis-research-views-from-the-dark-side
#5
REVIEW
Miranda M A Whitten, Christopher J Coates
Melanins (eumelanin and pheomelanin) are synthesised in insects for several purposes including cuticle sclerotisation and color patterning, clot formation, organogenesis and innate immunity. Traditional views of insect immunity detail the storage of pro-phenoloxidases inside specialized blood cells (hemocytes) and their release upon recognition of foreign bodies. Activated phenoloxidases convert monophenols into reactive quinones in a two-step enzymatic reaction, and until recently, the mechanism of tyrosine hydroxylation remained a mystery...
April 4, 2017: Pigment Cell & Melanoma Research
https://www.readbyqxmd.com/read/28364123/anomalous-evolution-of-broadband-optical-absorption-reveals-dynamic-solid-state-reorganization-during-eumelanin%C3%A2-build-up-in-thin-films
#6
Carmela Bonavolontà, Corrado de Lisio, Marco d'Ischia, Pasqualino Maddalena, Paola Manini, Alessandro Pezzella, Massimo Valentino
The origin of eumelanin optical properties remains a formidable conundrum preventing a detailed understanding of the complex photo-protective role of these widespread natural pigments and the rational design of innovative bioinspired materials for optoelectronic applications. Here we report the unusual kinetic and thickness-dependent evolution of the optical properties of black eumelanin polymers generated by spontaneous aerial polymerization of 5,6-dihydroxyindole (DHI) thin films (0.1-1 μm), consistent with peculiar solid state reorganization mechanisms governing broadband absorption...
March 31, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28332659/hydration-controlled-anisotropic-and-giant-permittivity-in-teg-functionalized-eumelanin
#7
Marianna Ambrico, Paolo F Ambrico, Teresa Ligonzo, Antonio Cardone, Maria Grazia Bridelli, Giuseppe Casamassima, Paola Manini, Marco d'Ischia
Although it has long been known that the peculiar electronic-ionic conductor behavior of eumelanin is critically dependent on hydration, the detailed mechanisms by which water-polymer interactions control and affect the conduction properties have remained largely obscure. In this paper, we report a remarkable anisotropy and giant polarization effect in a synthetic eumelanin (TEGMe) chemically functionalized with hydrophilic TEG residues. FT-IR analyses of water sorption isotherms and AC measurements were consistent with a microporous structure binding or hosting mainly isolated water molecules...
March 23, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28314098/pathways-for-excited-state-nonradiative-decay-of-5-6-dihydroxyindole-a-building-block-of-eumelanin
#8
Avdhoot Datar, Anirban Hazra
The photophysics of 5,6-dihydroxyindole (DHI) following excitation to its lowest two optically bright states was investigated using the complete active space self-consistent field method with second-order perturbative energy corrections. There is a barrierless pathway for the molecule to relax from the second-lowest bright state (2(1)ππ*) to the lowest bright state (1(1)ππ*). The 1(1)ππ* state has a conical intersection with the optically dark 1(1)πσ* state, which further intersects with the ground state along the NH and OH stretching coordinates...
April 3, 2017: Journal of Physical Chemistry. A
https://www.readbyqxmd.com/read/28271633/pheomelanogenesis-is-promoted-at-a-weakly-acidic-ph
#9
Kazumasa Wakamatsu, Ayano Nagao, Miu Watanabe, Kenta Nakao, Shosuke Ito
The diversity of pigmentation in the skin, hair, and eyes of humans has been largely attributed to the diversity of pH in melanosomes with an acidic pH being proposed to suppress melanin production, especially eumelanogenesis. We previously showed that an acidic pH greatly suppresses the late stage of eumelanogenesis after the dopachrome stage. The oxidation of tyrosine by tyrosinase in the presence of cysteine forms cysteinyldopa isomers, which are further oxidized to give rise to pheomelanin via benzothiazine intermediates...
May 2017: Pigment Cell & Melanoma Research
https://www.readbyqxmd.com/read/28240252/novel-quantitative-pigmentation-phenotyping-enhances-genetic-association-epistasis-and-prediction-of-human-eye-colour
#10
Andreas Wollstein, Susan Walsh, Fan Liu, Usha Chakravarthy, Mati Rahu, Johan H Seland, Gisèle Soubrane, Laura Tomazzoli, Fotis Topouzis, Johannes R Vingerling, Jesus Vioque, Stefan Böhringer, Astrid E Fletcher, Manfred Kayser
Success of genetic association and the prediction of phenotypic traits from DNA are known to depend on the accuracy of phenotype characterization, amongst other parameters. To overcome limitations in the characterization of human iris pigmentation, we introduce a fully automated approach that specifies the areal proportions proposed to represent differing pigmentation types, such as pheomelanin, eumelanin, and non-pigmented areas within the iris. We demonstrate the utility of this approach using high-resolution digital eye imagery and genotype data from 12 selected SNPs from over 3000 European samples of seven populations that are part of the EUREYE study...
February 27, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28195487/sequential-proton-coupled-electron-transfer-mediates-excited-state-deactivation-of-a-eumelanin-building-block
#11
Juan J Nogueira, Alice Corani, Amal El Nahhas, Alessandro Pezzella, Marco d'Ischia, Leticia González, Villy Sundström
Skin photoprotection is commonly believed to rely on the photochemistry of 5,6-dihydroxyindole (DHI)- and 5,6-dihydroxyindole-2-carboxylic acid (DHICA)-based eumelanin building blocks. Attempts to elucidate the underlying excited-state relaxation mechanisms have been partly unsuccessful due to the marked instability to oxidation. We report a study of the excited-state deactivation of DHI using steady-state and time-resolved fluorescence accompanied by high-level quantum-chemistry calculations including solvent effects...
February 16, 2017: Journal of Physical Chemistry Letters
https://www.readbyqxmd.com/read/28181477/eumelanin-releasing-spongy-like-hydrogels-for-skin-re-epithelialization-purposes
#12
Lucília Pereira da Silva, Sílvia Oliveira, Rogério Pirraco, Tírcia Santos, Rui Reis, Alexandra Marques, Vitor Correlo
Melanin function in the skin has been associated to pigmentation but other properties such as electrical conductance, photoprotection, antioxidant and antimicrobial activity, have also been recognized. Nonetheless, the use of melanin in a skin wound healing context was never considered. In this sense, eumelanin particles with a typical round and nano-sized morphology and electrical conductivity of 2.09x10-8S·cm-1 were extracted from the ink of Sepia officinalis. The ability of primary human keratinocytes to phagocyte eumelanin, which was then accumulated in cytosolic vesicles and nuclei surroundings, was demonstrated...
February 9, 2017: Biomedical Materials
https://www.readbyqxmd.com/read/28150707/eumelanin-broadband-absorption-develops-from-aggregation-modulated-chromophore-interactions-under-structural-and-redox-control
#13
Raffaella Micillo, Lucia Panzella, Mariagrazia Iacomino, Giacomo Prampolini, Ivo Cacelli, Alessandro Ferretti, Orlando Crescenzi, Kenzo Koike, Alessandra Napolitano, Marco d'Ischia
Eumelanins, the chief photoprotective pigments in man and mammals, owe their black color to an unusual broadband absorption spectrum whose origin is still a conundrum. Excitonic effects from the interplay of geometric order and disorder in 5,6-dihydroxyindole (DHI)-based oligomeric/polymeric structures play a central role, however the contributions of structural (scaffold-controlled) and redox (π-electron-controlled) disorder have remained uncharted. Herein, we report an integrated experimental-theoretical entry to eumelanin chromophore dynamics based on poly(vinyl alcohol)-controlled polymerization of a large set of 5,6-dihydroxyindoles and related dimers...
February 2, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28132436/the-potent-pro-oxidant-activity-of-rhododendrol-eumelanin-induces-cysteine-depletion-in-b16-melanoma-cells
#14
Shosuke Ito, Masae Okura, Kazumasa Wakamatsu, Toshiharu Yamashita
RS-4-(4-Hydroxyphenyl)-2-butanol (rhododendrol, RD), a skin-whitening agent, is known to induce leukoderma in some people. To explore the mechanism underlying this effect, we previously showed that the oxidation of RD with mushroom or human tyrosinase produces cytotoxic quinone oxidation products. We then examined the metabolism of RD in B16F1 melanoma cells in vitro and detected RD-pheomelanin and RD-quinone bound to non-protein and protein thiols. In this study, we examined the changes in glutathione (GSH) and cysteine in B16 cells exposed to RD for up to 24 h...
January 2017: Pigment Cell & Melanoma Research
https://www.readbyqxmd.com/read/28094871/divergence-of-camp-signaling-pathways-mediating-augmented-nucleotide-excision-repair-and-pigment-induction-in-melanocytes
#15
Erin M Wolf Horrell, Stuart G Jarrett, Katharine M Carter, John A D'Orazio
Loss-of-function melanocortin 1 receptor (MC1R) polymorphisms are common in UV-sensitive fair-skinned individuals and are associated with blunted cAMP second messenger signaling and higher lifetime risk of melanoma because of diminished ability of melanocytes to cope with UV damage. cAMP signaling positions melanocytes to resist UV injury by up-regulating synthesis of UV-blocking eumelanin pigment and by enhancing the repair of UV-induced DNA damage. cAMP enhances melanocyte nucleotide excision repair (NER), the genome maintenance pathway responsible for the removal of mutagenic UV photolesions, through cAMP-activated protein kinase (protein kinase A)-mediated phosphorylation of the ataxia telangiectasia mutated and Rad3 related (ATR) protein on the S435 residue...
January 17, 2017: Experimental Dermatology
https://www.readbyqxmd.com/read/28024137/-secrets-of-the-red-headed
#16
REVIEW
Zygmunt Zdrojewicz, Małgorzata Kowalik, Adam Jagodziński
Only 1-2% of people is red-headed but in the Russian Udmurt Republic or United Kingdom they can be met more often. A specific variant of MC1R gene (R allele) is responsible for the red hair. The gene encodes a receptor for melanocortins. These substances stimulate melanocytes to product melanin- a dye of the skin which is transported to keratinocytes. It protects a cellular nucleus from ultraviolet radiation. Melanin has two types: eumelanin which is dark brown or even black and red/orange pheomelanin. The second one is mostly observed in red-headed which is caused by R allele...
December 22, 2016: Polski Merkuriusz Lekarski: Organ Polskiego Towarzystwa Lekarskiego
https://www.readbyqxmd.com/read/28002950/energetics-of-radical-formation-in-eumelanin-building-blocks-implications-for-understanding-photoprotection-mechanisms-in-eumelanin
#17
Filipe Agapito, Benedito J Costa Cabral
The supramolecular structure of melanin pigments is characterized by a high concentration of radical species. Therefore, the energetics of the radical formation in melanin building blocks is key for understanding the structure and the electronic properties of the pigments at the molecular level. Nevertheless, the radical energetics of even the simplest melanin building blocks are largely unknown. In order to address this fundamental issue, the bond dissociation enthalpies (BDEs) for the melanin monomers 5,6-dihydroxy-1H-indole-2-carboxylic acid (DHICA), 1H-indole-5,6-diol (DHI), and 1H-indole-5,6-dione (IQ) were determined through high-accuracy ab initio quantum chemistry methods...
December 22, 2016: Journal of Physical Chemistry. A
https://www.readbyqxmd.com/read/27934397/nanoscale-disassembly-and-free-radical-reorganization-of-polydopamine-in-ionic-liquids
#18
Paola Manini, Piero Margari, Christian Pomelli, Paola Franchi, Gennaro Gentile, Alessandra Napolitano, Luca Valgimigli, Cinzia Chiappe, Vincent Ball, Marco d'Ischia
Despite the growing scientific and technological relevance of polydopamine (PDA), a eumelanin-like adhesive material widely used for surface functionalization and coating, knowledge of its structural and physicochemical properties, including in particular the origin of paramagnetic behavior, is still far from being complete. Herein, we disclose the unique ability of ionic liquids (ILs) to disassemble PDA, either as a suspension or as a thin film, up to the nanoscale, and to establish specific interactions with the free radical centers exposed by deaggregation of potential investigative value...
November 23, 2016: Journal of Physical Chemistry. B
https://www.readbyqxmd.com/read/27904077/synthesis-characterization-and-evaluation-of-thiazolidine-derivatives-of-cysteine-for-suppressing-eumelanin-production
#19
Yusuke Amino, Yoshinobu Takino, Megumi Kaneko, Fumie Ookura, Mai Yamamoto, Tatsuki Kashiwagi, Keiji Iwasaki
In the pathway of melanin biosynthesis, cysteine (Cys) is utilized for the synthesis of pheomelanin. Accordingly, Cys is considered to suppress the formation of brown-black eumelanin. Although attempts have been made to utilize Cys and its derivatives as skin-whitening agents, their instability and odor hinders their application as a cosmetic agent. Herein, N-acetyl-2-methylthiazolidine-2,4-dicarboxylic acid ethyl ester (AcCP2Et) was proposed as a candidate for a stable and prolonged-release derivative of Cys to inhibit dopachrome formation after its degradation in melanocytes...
2016: Chemical & Pharmaceutical Bulletin
https://www.readbyqxmd.com/read/27671997/not-another-type-of-potato-mc1r-and-the-russet-coloration-of-burmese-cats
#20
N A Gustafson, B Gandolfi, L A Lyons
The Burmese is a breed of domestic cat that originated in Southeast Asia and was further developed in the United States. Variants in melanocortin 1 receptor (MC1R) causes common coat colour phenotypes in a variety of mammalian species but only limited colour variation in the domestic cat. Known as the extension (E) locus, melanocortin 1 receptor (MC1R) interacts with the agouti locus to produce the eumelanin and pheomelanin pigments. Recently, a novel reddish coloration, which is termed russet, was identified in the Burmese cat breed...
February 2017: Animal Genetics
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