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Sample records for melanins

  1. Urine melanin

    MedlinePlus

    Normally, melanin is not present in urine. Normal value ranges may vary slightly among different laboratories. Some labs use different measurements or test different samples. Talk to your doctor about the meaning of your specific test results.

  2. Melanin-binding radiopharmaceuticals

    SciTech Connect

    Packer, S; Fairchild, R G; Watts, K P; Greenberg, D; Hannon, S J

    1980-01-01

    The scope of this paper is limited to an analysis of the factors that are important to the relationship of radiopharmaceuticals to melanin. While the authors do not attempt to deal with differences between melanin-binding vs. melanoma-binding, a notable variance is assumed. (PSB)

  3. Melanins from opioid peptides.

    PubMed

    Rosei, M A

    1996-12-01

    Opioid peptides and other Tyr-NH2-terminal peptides are substrates in vitro for mushroom and sepia tyrosine, giving rise to synthetic melanins retaining the peptide moiety (opiomelanins). The melanopeptides are characterized by a total solubility in hydrophylic solvents at neutral and basic pH. Opioid peptides (enkephalins, endorphins, and esorphins), if oxidized by tyrosinase in the presence of Dopa, are easily incorporated into Dopa-melanin, producing mixed-type pigments that can also be solubilized in hydrophylic solvents. Melanins derived from opioid peptides exhibit paramagnetism, as evidenced by an EPR spectrum identical to that of Dopa-melanin. However, the presence of the linked peptide chain is able to influence dramatically the electron transfer properties and the oxidizing behaviour of the melanopeptides, so that whereas Tyr-Gly-melanin appears to behave as Dopa-melanin, Enk-melanin does not exhibit any oxidizing activity. Opiomelanins are characterized by a peculiar UV-VIS spectrum; that is, by the presence of a distinct peak (330 nm) that disappears upon chemical treatment by acid hydrolysis. Opiomelanins are stable pigments at neutral and basic pH in the dark, whereas the addition of H2O2 leads to a 15% degradation. Under stimulated solar illumination, opiomelanins are more easily destroyed with respect to Dopa-melanin, with increasing degradation when exposed to increased hydrogen peroxide concentrations and more alkaline pH. Some speculations on the possible existence and role of opiomelanins have been outlined.

  4. The melanins and lipofuscin.

    PubMed

    Hack, M H; Helmy, F M

    1983-01-01

    An overview of the melanins and lipofuscin is presented, taking an integrating account of their morphological relationships and chemical characteristics wherever possible. This has required inclusion of the ommochromes, the schlerotizing process, and consideration of related neurotransmitters. A number of questions are raised and commented upon.

  5. Melanin pigmented solar absorbing surfaces

    SciTech Connect

    Gallas, J.M.; Eisner, M.

    1980-01-01

    Selectivity enhancement is shown to result for melanin, a black biopolymer pigment, for sufficiently low sample density. The effect is proposed to follow from a consideration of the evanescent waves associated with the total internal reflection phenomenon. A relationship is discussed among powder density, pH and the paramagnetic properties of melanin; this relationship is shown to be consistent with, and offer support to an amino-acid side group proposed earlier as part of the melanin structure. A brief discussion is also presented on the optical properties of melanin and the relative importance of quinhydrone, a change transfer complex believed to exist in the polymeric structure of melanin.

  6. Fluorescence of Melanin.

    NASA Astrophysics Data System (ADS)

    Gallas, James Martin

    1981-06-01

    Optical fluorescence in aqueous suspensions of synthetic dopa melanin has been detected and investigated. A fluorescence lifetime of 8.3 ns was measured in pulsed laser experiments. Fluorescence was observed for excitation between 290 and 420 nm. The emission as a function of wavelength displayed a single broad maximum falling between 440 and 480 nm, depending on excitation wavelength. The dependence of the quantum efficiency for fluorescence on parameters such as solution temperature, viscosity, pH, and concentration of metal ion, such as copper, has been investigated. The emission intensity decreased at both high and low values of pH, with increasing temperatures, and with increasing metal ion concentration, and decreasing viscosity. The pH dependence of the fluorescence can be related to changes in the ionization state of the various ionizable groups attached to the fluorophores. A self consistent model was developed in which proton transfer from these groups was fast compared with fluorescence rates for one type of fluorophore and slow compared with those for another type. The fluorescence dependence on copper ion concentration is explained in terms of a model invoking a reaction between melanin fluorophores and copper ions leading to the formation of a melanin-copper complex which is itself fluorescent. A model incorporating diffusion controlled chemical reactions between fluorescents groups and quencher groups on the melanin polymer is developed and used to explain the observed dependence of melanin fluorescence on solvent viscosity. Over the temperature range 20(DEGREES)C-70(DEGREES)C, an Arrhenius type behavior was found with an activation enthalpy of 1.3 Kcal/mole. Using the temperature dependence of the viscous quenching model as well as the temperature dependence of the fluorophore-radical equilibrium concentration leads to a temperature dependence which is in reasonable agreement with the observed behavior. Many aspects of the experimental results

  7. Spectroscopic Studies of Melanin.

    DTIC Science & Technology

    1986-01-01

    il), and leading to the production of oxygen radicals (12). Gallas (13) and Kozikowski et al. (14) have studied melanin fluorescence. As part of a...Raman scattering unobservable in aqueous solution by continuous wave techniques. As was also observed by Kozikowski et al. (14), the intrinsic...168B. 14. Kozikowski SD, Wolfram LJ, Alfano RR. Fluorescence spectroscopy of eumelanins. IEEE J Quant Electron 1984;OE20:1379-1382. 15. Slawinski J

  8. Role of Melanin in Oncogenesis

    DTIC Science & Technology

    2011-08-01

    AD_________________ Award Number: W81XWH-10-1-0066 TITLE: Role of Melanin in Oncogenesis... Melanin in Oncogenesis 5b. GRANT NUMBER W81XWH-10-1-0066 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) 5d. PROJECT NUMBER Vashisht Gopal Yennu...excess melanin production in melanocytes accumulated in localized areas of the skin, leading to formation of benign nevi and infrequently

  9. Role of Melanin in Oncogenesis

    DTIC Science & Technology

    2011-02-28

    1-0066 TITLE: Role of Melanin in Oncogenesis PRINCIPAL INVESTIGATOR: Vashisht Gopal Yennu-Nanda CONTRACTING...28-FEB-2011 2. REPORT TYPE FINAL 3. DATES COVERED (From - To) 1 Feb 2010 – 31 January 2011 4. TITLE AND SUBTITLE Role of Melanin in...SUPPLEMENTARY NOTES 14. ABSTRACT Increased solar radiation and other unknown factors induce excess melanin production in melanocytes accumulated in localized

  10. Photoacoustic measurement of epidermal melanin

    NASA Astrophysics Data System (ADS)

    Viator, John A.; Svaasand, Lars O.; Aguilar, Guillermo; Choi, Bernard; Nelson, J. Stuart

    2003-06-01

    Most dermatologic laser procedures must consider epidermal melanin, as it is a broadband optical absorber which affects subsurface fluence, effectively limiting the amount of light reaching the dermis and targeted chromophores. An accurate method for quantifying epidermal melanin content would aid clinicians in determining proper light dosage for therapeutic laser procedures. While epidermal melanin content has been quantified non-invasively using optical methods, there is currently no way to determine the melanin distribution in the epidermis. We have developed a photoacoustic probe that uses a Q-switched, frequency doubled Nd:YAG laser operating at 532nm to generate acoustic pulses in skin in vivo. The probe contained a piezoelectric element that detected photoacoustic waves which were then analyzed for epidermal melanin content, using a photoacoustic melanin index (PAMI). We tested 15 human subjects with skin types I--VI using the photoacoustic probe. We also present photoacoustic data for a human subject with vitiligo. Photoacoustic measurement showed melanin in the vitiligo subject was almost completely absent.

  11. Pathogenic Roles for Fungal Melanins

    PubMed Central

    Jacobson, Eric S.

    2000-01-01

    Melanins represent virulence factors for several pathogenic fungi; the number of examples is growing. Thus, albino mutants of several genera (in one case, mutated precisely in the melanizing enzyme) exhibit decreased virulence in mice. We consider the phenomenon in relation to known chemical properties of melanin, beginning with biosynthesis from ortho-hydroquinone precursors which, when oxidized enzymatically to quinones, polymerize spontaneously to melanin. It follows that melanizing intermediates are cross-linking reagents; melanization stabilizes the external cell wall against hydrolysis and is thought to determine semipermeability in the osmotic ram (the appressorium) of certain plant pathogens. Polymeric melanins undergo reversible oxidation-reduction reactions between cell wall-penetrating quinone and hydroquinone oxidation states and thus represent polymeric redox buffers; using strong oxidants, it is possible to titrate the melanin on living cells and thereby demonstrate protection conferred by melanin in several species. The amount of buffering per cell approximately neutralizes the amount of oxidant generated by a single macrophage. Moreover, the intermediate oxidation state, the semiquinone, is a very stable free radical and is thought to trap unpaired electrons. We have suggested that the oxidation state of external melanin may be regulated by external Fe(II). An independent hypothesis holds that in Cryptococcus neoformans, an important function of the melanizing enzyme (apart from melanization) is the oxidation of Fe(II) to Fe(III), thereby forestalling generation of the harmful hydroxyl radical from H2O2. Thus, problems in fungal pathogenesis have led to evolving hypotheses regarding melanin functioning. PMID:11023965

  12. Radicals in melanin biochemistry.

    PubMed

    Riley, P A

    1988-01-01

    Melanins are light-absorbant polymeric pigments found widely dispersed in nature. They possess many interesting physicochemical properties. One of these is the expression in the polymer of stable free radicals which appear to have a protective action in cells, probably by acting as a sink for diffusible free-radical species. Polymer formation is thought to occur by a free-radical process in which semiquinones are added to the chain. Semiquinones are formed by redox equilibration interactions between metabolic intermediates formed during the tyrosinase-catalyzed oxidation process. In the continued presence of substrate, steady-state concentrations of reactive species are predicted in the reaction system, and the melanogenic pathway may be considered as potentially hazardous for pigment-generating cells. This feature has been exploited by the use of analogue substrates to generate cytotoxic species as a possible rational approach to the treatment of malignant melanoma. One such substance is 4-hydroxyanisole, the oxidation of which gives rise to semiquinone radical species. The possibility that the anisyl semiquinone initiates a mechanism leading to cell damage has not been excluded. However, the current view is that the major cytotoxicity due to the oxidation products of this compound is the result of the action of the corresponding orthoquinone. A number of mechanisms exist for detoxifying quinones if they reach the cytosol such as O-methylation and the formation of thiol adducts with cysteine or glutathione, and these can be used as markers of melanogenesis. In general, however, only small amounts of reactive intermediates of melanogenesis escape from the confines of the melanosome, probably because of their limited lipid solubility. The selective toxic action of anisyl quinone in the treatment of melanoma may, in part, be due to membrane defects in the melanosomes of malignant melanocytes.

  13. Physical factors affecting chloroquine binding to melanin.

    PubMed

    Schroeder, R L; Pendleton, P; Gerber, J P

    2015-10-01

    Chloroquine is an antimalarial drug but is also prescribed for conditions such as rheumatoid arthritis. Long-term users risk toxic side effects, including retinopathy, thought to be caused by chloroquine accumulation on ocular melanin. Although the binding potential of chloroquine to melanin has been investigated previously, our study is the first to demonstrate clear links between chloroquine adsorption by melanin and system factors including temperature, pH, melanin type, and particle size. In the current work, two Sepia melanins were compared with bovine eye as a representative mammalian melanin. Increasing the surface anionic character due to a pH change from 4.7 to 7.4 increased each melanin's affinity for chloroquine. Although the chloroquine isotherms exhibited an apparently strong interaction with each melanin, isosteric heat analysis indicated a competitive interaction. Buffer solution cations competed effectively at low surface coverage; chloroquine adsorption occurs via buffer cation displacement and is promoted by temperature-influenced secondary structure swelling.

  14. Fungal melanins differ in planar stacking distances.

    PubMed

    Casadevall, Arturo; Nakouzi, Antonio; Crippa, Pier R; Eisner, Melvin

    2012-01-01

    Melanins are notoriously difficult to study because they are amorphous, insoluble and often associated with other biological materials. Consequently, there is a dearth of structural techniques to study this enigmatic pigment. Current models of melanin structure envision the stacking of planar structures. X ray diffraction has historically been used to deduce stacking parameters. In this study we used X ray diffraction to analyze melanins derived from Cryptococcus neoformans, Aspergillus niger, Wangiella dermatitides and Coprinus comatus. Analysis of melanin in melanized C. neoformans encapsulated cells was precluded by the fortuitous finding that the capsular polysaccharide had a diffraction spectrum that was similar to that of isolated melanin. The capsular polysaccharide spectrum was dominated by a broad non-Bragg feature consistent with origin from a repeating structural motif that may arise from inter-molecular interactions and/or possibly gel organization. Hence, we isolated melanin from each fungal species and compared diffraction parameters. The results show that the inferred stacking distances of fungal melanins differ from that reported for synthetic melanin and neuromelanin, occupying intermediate position between these other melanins. These results suggest that all melanins have a fundamental diffracting unit composed of planar graphitic assemblies that can differ in stacking distance. The stacking peak appears to be a distinguishing universal feature of melanins that may be of use in characterizing these enigmatic pigments.

  15. Fungal Melanins Differ in Planar Stacking Distances

    PubMed Central

    Casadevall, Arturo; Nakouzi, Antonio; Crippa, Pier R.; Eisner, Melvin

    2012-01-01

    Melanins are notoriously difficult to study because they are amorphous, insoluble and often associated with other biological materials. Consequently, there is a dearth of structural techniques to study this enigmatic pigment. Current models of melanin structure envision the stacking of planar structures. X ray diffraction has historically been used to deduce stacking parameters. In this study we used X ray diffraction to analyze melanins derived from Cryptococcus neoformans, Aspergillus niger, Wangiella dermatitides and Coprinus comatus. Analysis of melanin in melanized C. neoformans encapsulated cells was precluded by the fortuitous finding that the capsular polysaccharide had a diffraction spectrum that was similar to that of isolated melanin. The capsular polysaccharide spectrum was dominated by a broad non-Bragg feature consistent with origin from a repeating structural motif that may arise from inter-molecular interactions and/or possibly gel organization. Hence, we isolated melanin from each fungal species and compared diffraction parameters. The results show that the inferred stacking distances of fungal melanins differ from that reported for synthetic melanin and neuromelanin, occupying intermediate position between these other melanins. These results suggest that all melanins have a fundamental diffracting unit composed of planar graphitic assemblies that can differ in stacking distance. The stacking peak appears to be a distinguishing universal feature of melanins that may be of use in characterizing these enigmatic pigments. PMID:22359541

  16. Spiders do have melanin after all.

    PubMed

    Hsiung, Bor-Kai; Blackledge, Todd A; Shawkey, Matthew D

    2015-11-01

    Melanin pigments are broadly distributed in nature - from bacteria to fungi to plants and animals. However, many previous attempts to identify melanins in spiders were unsuccessful, suggesting that these otherwise ubiquitous pigments were lost during spider evolution. Yet, spiders exhibit many dark colours similar to those produced by melanins in other organisms, and the low solubility of melanins makes isolation and characterization difficult. Therefore, whether melanins are truly absent or have simply not yet been detected is an open question. Raman spectroscopy provides a reliable way to detect melanins in situ, without the need for isolation. In this study, we document the presence of eumelanin in diverse species of spiders using confocal Raman microspectroscopy. Comparisons of spectra with theoretically calculated data falsify the previous hypothesis that dark colours are produced solely by ommochromes in spiders. Our data indicate that melanins are present in spiders and further supporting that they are present in most living organisms.

  17. Synthesis and assembly of fungal melanin.

    PubMed

    Eisenman, Helene C; Casadevall, Arturo

    2012-02-01

    Melanin is a unique pigment with myriad functions that is found in all biological kingdoms. It is multifunctional, providing defense against environmental stresses such as ultraviolet (UV) light, oxidizing agents and ionizing radiation. Melanin contributes to the ability of fungi to survive in harsh environments. In addition, it plays a role in fungal pathogenesis. Melanin is an amorphous polymer that is produced by one of two synthetic pathways. Fungi may synthesize melanin from endogenous substrate via a 1,8-dihydroxynaphthalene (DHN) intermediate. Alternatively, some fungi produce melanin from L-3,4-dihydroxyphenylalanine (L-dopa). The detailed chemical structure of melanin is not known. However, microscopic studies show that it has an overall granular structure. In fungi, melanin granules are localized to the cell wall where they are likely cross-linked to polysaccharides. Recent studies suggest the fungal melanin may be synthesized in internal vesicles akin to mammalian melanosomes and transported to the cell wall. Potential applications of melanin take advantage of melanin's radioprotective properties and propensity to bind to a variety of substances.

  18. Synthesis and assembly of fungal melanin

    PubMed Central

    Casadevall, Arturo

    2015-01-01

    Melanin is a unique pigment with myriad functions that is found in all biological kingdoms. It is multifunctional, providing defense against environmental stresses such as ultraviolet (UV) light, oxidizing agents and ionizing radiation. Melanin contributes to the ability of fungi to survive in harsh environments. In addition, it plays a role in fungal pathogenesis. Melanin is an amorphous polymer that is produced by one of two synthetic pathways. Fungi may synthesize melanin from endogenous substrate via a 1,8-dihydroxynaphthalene (DHN) intermediate. Alternatively, some fungi produce melanin from l-3,4-dihydroxyphenylalanine (l-dopa). The detailed chemical structure of melanin is not known. However, microscopic studies show that it has an overall granular structure. In fungi, melanin granules are localized to the cell wall where they are likely cross-linked to polysaccharides. Recent studies suggest the fungal melanin may be synthesized in internal vesicles akin to mammalian melanosomes and transported to the cell wall. Potential applications of melanin take advantage of melanin's radioprotective properties and propensity to bind to a variety of substances. PMID:22173481

  19. Pneumocystis Melanins Confer Enhanced Organism Viability

    PubMed Central

    Icenhour, Crystal R.; Kottom, Theodore J.; Limper, Andrew H.

    2006-01-01

    Pneumocystis continues to represent an important opportunistic fungal pathogen of those with compromised immunity. Thus, it is crucial to identify factors that affect its viability and pathogenicity. We previously reported the first identification of melanins in Pneumocystis. In the present study, we sought to further characterize these components and define the function for these melanins. Melanins extracted from Pneumocystis and melanized Pneumocystis cells were analyzed by electron spin resonance spectroscopy, revealing spectra consistent with melanins from other fungi. Immunofluorescence assays using anti-melanin monoclonal antibodies showed that melanins are widely present across Pneumocystis host species, including mouse-, ferret-, and human-derived Pneumocystis organisms, as well as Pneumocystis carinii derived from rat. Using immunoelectron microscopy, melanins were found to localize to the cell wall and cytoplasm of P. carinii cysts, as well as to intracystic bodies within mature cysts. Next, the role of melanins on the maintenance of Pneumocystis viability was determined by using quantitative reverse transcription-PCR measurement of the heat shock protein mRNA under adverse environmental conditions. Using a new method to promote the melanization of Pneumocystis, we observed that strongly melanized Pneumocystis retained viability to a greater degree when exposed to UV irradiation or desiccation compared to less-pigmented organisms. These studies support our previous identification of Pneumocystis melanins across the genus, further characterize these Pneumocystis components, and demonstrate that melanins protect Pneumocystis from environmental stressors. PMID:16757739

  20. Pneumocystis melanins confer enhanced organism viability.

    PubMed

    Icenhour, Crystal R; Kottom, Theodore J; Limper, Andrew H

    2006-06-01

    Pneumocystis continues to represent an important opportunistic fungal pathogen of those with compromised immunity. Thus, it is crucial to identify factors that affect its viability and pathogenicity. We previously reported the first identification of melanins in Pneumocystis. In the present study, we sought to further characterize these components and define the function for these melanins. Melanins extracted from Pneumocystis and melanized Pneumocystis cells were analyzed by electron spin resonance spectroscopy, revealing spectra consistent with melanins from other fungi. Immunofluorescence assays using anti-melanin monoclonal antibodies showed that melanins are widely present across Pneumocystis host species, including mouse-, ferret-, and human-derived Pneumocystis organisms, as well as Pneumocystis carinii derived from rat. Using immunoelectron microscopy, melanins were found to localize to the cell wall and cytoplasm of P. carinii cysts, as well as to intracystic bodies within mature cysts. Next, the role of melanins on the maintenance of Pneumocystis viability was determined by using quantitative reverse transcription-PCR measurement of the heat shock protein mRNA under adverse environmental conditions. Using a new method to promote the melanization of Pneumocystis, we observed that strongly melanized Pneumocystis retained viability to a greater degree when exposed to UV irradiation or desiccation compared to less-pigmented organisms. These studies support our previous identification of Pneumocystis melanins across the genus, further characterize these Pneumocystis components, and demonstrate that melanins protect Pneumocystis from environmental stressors.

  1. Computational model of heterogeneous heating in melanin

    NASA Astrophysics Data System (ADS)

    Kellicker, Jason; DiMarzio, Charles A.; Kowalski, Gregory J.

    2015-03-01

    Melanin particles often present as an aggregate of smaller melanin pigment granules and have a heterogeneous surface morphology. When irradiated with light within the absorption spectrum of melanin, these heterogeneities produce measurable concentrations of the electric field that result in temperature gradients from thermal effects that are not seen with spherical or ellipsoidal modeling of melanin. Modeling melanin without taking into consideration the heterogeneous surface morphology yields results that underestimate the strongest signals or over{estimate their spatial extent. We present a new technique to image phase changes induced by heating using a computational model of melanin that exhibits these surface heterogeneities. From this analysis, we demonstrate the heterogeneous energy absorption and resulting heating that occurs at the surface of the melanin granule that is consistent with three{photon absorption. Using the three{photon dluorescence as a beacon, we propose a method for detecting the extents of the melanin granule using photothermal microscopy to measure the phase changes resulting from the heating of the melanin.

  2. Synthesis and characterization of melanin in DMSO

    NASA Astrophysics Data System (ADS)

    Bronze-Uhle, Erika S.; Batagin-Neto, Augusto; Xavier, Pedro H. P.; Fernandes, Nicole I.; de Azevedo, Eduardo R.; Graeff, Carlos F. O.

    2013-09-01

    Recently soluble melanin derivatives have been obtained by a synthetic procedure carried out in DMSO (D-melanin). In this work a comparative study of the structural characteristics of synthetic melanin derivatives obtained by oxidation of L-DOPA in H2O and DMSO are presented. To this end, Fourier-transform infrared spectroscopy as well as proton and carbon nuclear magnetic resonance techniques has been employed. In addition, aging effects have been investigated for D-melanin. The results suggest that sulfonate groups (-SO2CH3) from the oxidation of DMSO, are incorporated into melanin, which confers protection to the phenolic hydroxyl group present in its structure. The solubility of D-melanin in DMSO is attributed to the presence of these groups. When D-melanin is left in air for long time periods, the sulfonate groups leave the structure, and an insoluble compound is obtained. NaOH and water have been used, in order to accelerate the release of the sulfonate groups attached to D-melanin, thereby corroborating the proposed structure and the synthesis mechanism.

  3. Some biochemical properties of melanins from opioid peptides.

    PubMed

    Rosei, M A; Mosca, L; Coccia, R; Blarzino, C; Musci, G; De Marco, C

    1994-03-02

    Opioid peptides are converted by mushroom tyrosinase into melanin-like compounds retaining the peptide moiety (opio-melanins). Opio-melanins, owing to the presence of the linked aminoacids and in contrast with DOPA-melanin, are soluble compounds. The enkephalin-generated melanins are cleaved by carboxypeptidase A and pronase whereas aminopeptidase M cannot remove aminoacids from the pigment. Enkephalins, as well as other opioid peptides, (alpha-endorphin, kyotorphin, esorphins) if oxidized in presence of DOPA and tyrosinase are readily incorporated into DOPA-melanin. The resulting mixed-melanins (opio-melanin + DOPA-melanin) can be solubilized in hydrophilic solvents. Melanin from leu-enkephalin exhibits paramagnetism as evidenced by an EPR spectrum identical to that of DOPA-melanin, but unlike the latter pigment, it does not appear to oxidize NADH, probably for the presence of the peptide moiety that exerts a hampering effect on the oxidizing capacity.

  4. Melanin biosynthesis during differentiation of Physarum polycephalum.

    PubMed

    Chet, I; Hüttermann, A

    1977-08-25

    Melanin synthesis in the myxomycete Physarum polycephalum occurs during sporulation but not during spherule formation. Melanin-like pigment was extracted from spores. An almost identical substance of polyphenols was extracted from spherules and characterized by its ultraviolet and infrared absorbance spectra. Polyphenol oxidase activity in spherules was very low and showed only one weak isoenzyme band in isoelectric focusing polyacrylamide gels. A much higher activity, and an increasing number of isoenzymes, were detected in sporulating cultures after illumination during the differentiation process. The addition of melanin precursors resulted in the synthesis of brownish-yellow spherules, probably containing dopachrome, whereas the addition of polyphenol oxidase inhibitors resulted in yellow sporangia. The results indicate that melanin synthesis is probably only a stage in maturation but not an essential part of the morphogenetic process itself.

  5. Microbial melanins for radioprotection and bioremediation.

    PubMed

    Cordero, Radames J B; Vij, Raghav; Casadevall, Arturo

    2017-09-01

    Microbial melanins provide a biocompatible and scalable approach for bioremediation and radioprotection technologies due to their physicochemical properties. © 2017 The Authors. Microbial Biotechnology published by John Wiley & Sons Ltd and Society for Applied Microbiology.

  6. Actinobacterial melanins: current status and perspective for the future.

    PubMed

    Manivasagan, Panchanathan; Venkatesan, Jayachandran; Sivakumar, Kannan; Kim, Se-Kwon

    2013-10-01

    Melanins are enigmatic pigments that are produced by a wide variety of microorganisms including several species of bacteria and fungi. Melanins are biological macromolecules with multiple important functions, yet their structures are not well understood. Melanins are frequently used in medicine, pharmacology, and cosmetics preparations. Melanins also have great application potential in agriculture industry. They have several biological functions including photoprotection, thermoregulation, action as free radical sinks, cation chelators, and antibiotics. Plants and insects incorporate melanins as cell wall and cuticle strengtheners, respectively. Actinobacteria are the most economically as well as biotechnologically valuable prokaryotes. However, the melanin properties are, in general, poorly understood. In this review an evaluation is made on the present state of research on actinobacterial melanins and its perspectives. The highlights include the production and biotechnological applications of melanins in agriculture, food, cosmetic and medicinal fields. With increasing advancement in science and technology, there would be greater demands in the future for melanins produced by actinobacteria from various sources.

  7. DOPA and DHN pathway orchestrate melanin synthesis in Aspergillus species.

    PubMed

    Pal, Anuradha K; Gajjar, Devarshi U; Vasavada, Abhay R

    2014-01-01

    Melanins are high molecular weight hydrophobic pigments that have been studied for their role in the virulence of fungal pathogens. We investigated the amount and type of melanin in 20 isolates of Aspergillus spp.; A. niger (n = 3), A. flavus (n = 5), A. tamarii (n = 3), A. terreus (n = 3), A. tubingensis (n = 3), A. sydowii (n = 3). Aspergillus spp. were identified by sequencing the internal transcribed spacer (ITS) region. Extraction of melanin from culture filtrate and fungal biomass was done and followed by qualitative and quantitative analysis of melanin pigment. Ultraviolet (UV), Fourier transformed infrared (FT-IR), and electron paramagnetic resonance (EPR) spectra analyses confirmed the presence of melanin. The melanin pathway was studied by analyzing the effects of inhibitors; kojic acid, tropolone, phthalide, and tricyclazole. The results indicate that in A. niger and A. tubingensis melanin was found in both culture filtrate and fungal biomass. For A. tamarii and A. flavus melanin was extracted from biomass only, whereas melanin was found only in culture filtrate for A. terreus. A negligible amount of melanin was found in A. sydowii. The maximum amount of melanin from culture filtrate and fungal biomass was found in A. niger and A. tamarrii, respectively. The DOPA (3,4-dihydroxyphenylalanine) pathway produces melanin in A. niger, A. tamarii and A. flavus, whereas the DHN (1,8-dihydroxynaphthalene) pathway produces melanin in A. tubingensis and A. terreus. It can be concluded that the amount and type of melanin in aspergilli largely differ from species to species.

  8. Study of melanin bleaching after immunohistochemistry of melanin-containing tissues.

    PubMed

    Shen, Hongwu; Wu, Wenqiao

    2015-04-01

    Melanin may interfere with immunohistochemical staining. The goal of this study was to investigate the effects of trichloroisocyanuric acid (TCCA) bleaching, potassium permanganate bleaching, and potassium dichromate bleaching on melanin, tissue antigen, and 3,3'-diaminobenzidine (DAB) using melanin-containing and melanin-free tissue samples. Our results demonstrated that all 3 bleaching methods efficiently bleached melanin and partially destroyed tissue antigen. In addition, potassium permanganate bleaching and potassium dichromate bleaching clearly destroyed DAB, whereas TCCA bleaching had no significant effect on DAB. Therefore, neither potassium permanganate nor potassium dichromate is an ideal solution, whereas TCCA might be an ideal solution for melanin bleaching after the immunohistochemical staining of melanin-containing tissues. After immunostaining followed by TCCA bleaching, the melanin could be completely removed in all 120 malignant melanoma tissue sections. Compared with the control, the DAB intensity was clear, and the tissue structure and cellular nuclei were well maintained. It is worth noting that TCCA should be freshly prepared before each experiment, and used within 2 hours of its preparation. In addition, sections should not be incubated with TCCA for over 30 minutes.

  9. Study of Melanin Bleaching After Immunohistochemistry of Melanin-containing Tissues

    PubMed Central

    Wu, Wenqiao

    2015-01-01

    Melanin may interfere with immunohistochemical staining. The goal of this study was to investigate the effects of trichloroisocyanuric acid (TCCA) bleaching, potassium permanganate bleaching, and potassium dichromate bleaching on melanin, tissue antigen, and 3,3′-diaminobenzidine (DAB) using melanin-containing and melanin-free tissue samples. Our results demonstrated that all 3 bleaching methods efficiently bleached melanin and partially destroyed tissue antigen. In addition, potassium permanganate bleaching and potassium dichromate bleaching clearly destroyed DAB, whereas TCCA bleaching had no significant effect on DAB. Therefore, neither potassium permanganate nor potassium dichromate is an ideal solution, whereas TCCA might be an ideal solution for melanin bleaching after the immunohistochemical staining of melanin-containing tissues. After immunostaining followed by TCCA bleaching, the melanin could be completely removed in all 120 malignant melanoma tissue sections. Compared with the control, the DAB intensity was clear, and the tissue structure and cellular nuclei were well maintained. It is worth noting that TCCA should be freshly prepared before each experiment, and used within 2 hours of its preparation. In addition, sections should not be incubated with TCCA for over 30 minutes. PMID:24710084

  10. Photoprotective actions of natural and synthetic melanins.

    PubMed

    Krol, E S; Liebler, D C

    1998-12-01

    Melanins are thought to be important modulators of photochemistry in skin. Eumelanin, a black-brown pigment, is believed to protect against UV-induced photodamage, whereas pheomelanin, a red-yellow pigment, is believed to possess photosensitizing properties. To investigate the hypothesized dichotomy of melanins as both photoprotectants and photosensitizers, we examined the effects of melanins on UV-induced liposomal lipid peroxidation. Sepia melanin, a representative eumelanin, and both red hair pheomelanin and synthetic pheomelanin were employed in these studies. Both eumelanin and pheomelanin inhibited UVA/B- and UVA-induced liposomal lipid peroxidation in a concentration-dependent manner as measured by inhibition of conjugated diene formation. No change in protective properties of the melanins was observed in the presence of saturating levels of O2 during UVA irradiation. Pheomelanin irradiated with UVA/B or UVA induced superoxide-catalyzed reduction of nitroblue tetrazolium, whereas eumelanin did not. Melanins are known to bind various metals, and we examined the effect of iron on the photoproperties of melanins. Eumelanin complexed with Fe(III) did not inhibit UVA/B-induced lipid peroxidation, whereas pheomelanin complexed with Fe(III) stimulated UVA/B-induced lipid peroxidation. Thus, complexation with iron reversed the antioxidant effect of eumelanin and converted pheomelanin into a prooxidant. Analysis of lipid peroxidation products indicated that the oxidation was mediated by free radicals rather than by singlet oxygen. These data indicate that both eumelanin and pheomelanin exert antioxidant effects against UV-induced lipid peroxidation but that the prooxidant activities of pheomelanin result from pheomelanin-metal complexation.

  11. Interaction of melanosomal proteins with melanin.

    PubMed

    Donatien, P D; Orlow, S J

    1995-08-15

    Melanin is deposited in melanosomes upon a proteinaceous matrix enveloped by a melanosomal membrane. Since melanin is highly detergent insoluble, we hypothesized that the detergent solubility of proteins of the melanosomal matrix might be inversely related to the state of melanosomal melanization. Immunoblotting analyses were performed on extracts of albino and black melanocytes to test this hypothesis. The protein products of the silver (si) and the pink-eyed-dilution (p) loci as well as other matrix constituents were present at twofold higher levels in extracts of albino cells. When black cells were rendered amelanotic by growing cultures in the presence of the tyrosinase inhibitor phenylthiourea, the apparent levels of these proteins were also increased. To obviate the potential role of different levels of synthesis in contributing to these differences, we developed a cell-free melanosomal melanization assay. Upon incubation of a melanosome-rich fraction with the melanin precursor L-3,4-dihydroxyphenylalanine (Dopa) followed by immunoblot analysis, the si locus protein, the p locus protein, and other putative matrix constituents became rapidly insoluble in SDS when compared with the members of the tyrosinase-related family of melanosomal membrane proteins. Our results suggest that melanosomal proteins that interact with melanin may be identified by their relative insolubility in SDS under conditions of increasing melanization. In addition to the si locus protein and other putative melanosomal matrix proteins, the membrane-bound p locus protein may also interact closely with melanin.

  12. Thermohydrogel Containing Melanin for Photothermal Cancer Therapy.

    PubMed

    Kim, Miri; Kim, Hyun Soo; Kim, Min Ah; Ryu, Hyanghwa; Jeong, Hwan-Jeong; Lee, Chang-Moon

    2016-12-01

    Melanin is an effective absorber of light and can extend to near infrared (NIR) regions. In this study, a natural melanin is presented as a photothermal therapeutic agent (PTA) because it provides a good photothermal conversion efficiency, shows biodegradability, and does not induce long-term toxicity during retention in vivo. Poloxamer solution containing melanin (Pol-Mel) does not show any precipitation and shows sol-gel transition at body temperature. After irradiation from 808 nm NIR laser at 1.5 W cm(-2) for 3 min, the photothermal conversion efficiency of Pol-Mel is enough to kill cancer cells in vitro and in vivo. The tumor growth of mice bearing CT26 tumors treated with Pol-Mel injection and laser irradiation is suppressed completely without recurrence postirradiation. All these results indicate that Pol-Mel can become an attractive PTA for photothermal cancer therapy.

  13. Laser desorption ionization mass spectrometry in the study of natural and synthetic melanins. II--Serotonin melanins.

    PubMed

    Bertazzo, A; Biasiolo, M; Costa, C; Allegri, G; Elli, G; Seraglia, R; Traldi, P

    1994-07-01

    Various biosynthetic melanins obtained by enzymic oxidation of serotonin with polyphenol oxidase from Psalliota campestris mushroom or potato, and with tyrosinase from Sepia officinalis or from Sigma were studied by means of laser desorption ionization mass spectrometry. Various oligomeric clusters were evidenced, proving that the examined melanins are composed of sets of different oligomers, the production of which strongly depends on the enzyme reaction. While serotonin melanins obtained with polyphenol oxidase from potato showed wide species distribution with molecular weights ranging from 2008 to 13,000 Da, the same melanins obtained from mushroom showed oligomer distributions from 1505 to 9000 Da. Serotonin melanins prepared with tyrosinase from Sepia showed oligomers from 1636 to 18,000 Da. A dopa-melanin obtained with mushroom polyphenol oxidase showed oligomer species from 1709 to 17,874 Da. Comparison of molecular weight distributions of the various oligomer sets in serotonin melanins with those in tyrosine melanins revealed clear differences, which are investigated and discussed.

  14. Melanin: The Effects of Dimethyl Sulfoxide on the Spectral Properties.

    DTIC Science & Technology

    1986-01-01

    Kozikowski et al (14) recently observed fluorescence of melanins from argon ion laser excitation. Infrared absorption spectra of melanin compressed...Photobiol 1978;28:75-81. 13. Gallas JP. Fluorescence of melanin. Dtiss Abstr Int 1982;43:1681. 14. Kozikowski SD, Wolfram LJ, Alfano RR. Fluorescence

  15. Identification of 180 million years old, probably unchanged melanine

    NASA Technical Reports Server (NTRS)

    Beyermann, K.; Hasenmaier, D.

    1977-01-01

    The comparison of the infrared spectra of recent sepia melanine and of the content of the ink sac of fossilized cuttlefish indicates that the 180 million years old substance is unchanged melanine. Both substances behave identically on heating. Other procedures for identification of melanine are surveyed critically.

  16. Melanin as an active layer in biosensors

    SciTech Connect

    Piacenti da Silva, Marina Congiu, Mirko Oliveira Graeff, Carlos Frederico de; Fernandes, Jéssica Colnaghi Biziak de Figueiredo, Natália Mulato, Marcelo

    2014-03-15

    The development of pH sensors is of great interest due to its extensive application in several areas such as industrial processes, biochemistry and particularly medical diagnostics. In this study, the pH sensing properties of an extended gate field effect transistor (EGFET) based on melanin thin films as active layer are investigated and the physical mechanisms related to the device operation are discussed. Thin films were produced from different melanin precursors on indium tin oxide (ITO) and gold substrates and were investigated by Atomic Force Microscopy and Electrochemical Impedance Spectroscopy. Experiments were performed in the pH range from 2 to 12. EGFETs with melanin deposited on ITO and on gold substrates showed sensitivities ranging from 31.3 mV/pH to 48.9 mV/pH, depending on the melanin precursor and the substrate used. The pH detection is associated with specific binding sites in its structure, hydroxyl groups and quinone imine.

  17. Melanin, Radiation, and Energy Transduction in Fungi.

    PubMed

    Casadevall, Arturo; Cordero, Radames J B; Bryan, Ruth; Nosanchuk, Joshua; Dadachova, Ekaterina

    2017-03-01

    Melanin pigments are found in many diverse fungal species, where they serve a variety of functions that promote fitness and cell survival. Melanotic fungi inhabit some of the most extreme habitats on earth such as the damaged nuclear reactor at Chernobyl and the highlands of Antarctica, both of which are high-radiation environments. Melanotic fungi migrate toward radioactive sources, which appear to enhance their growth. This phenomenon, combined with the known capacities of melanin to absorb a broad spectrum of electromagnetic radiation and transduce this radiation into other forms of energy, raises the possibility that melanin also functions in harvesting such energy for biological usage. The ability of melanotic fungi to harness electromagnetic radiation for physiological processes has enormous implications for biological energy flows in the biosphere and for exobiology, since it provides new mechanisms for survival in extraterrestrial conditions. Whereas some features of the way melanin-related energy transduction works can be discerned by linking various observations and circumstantial data, the mechanistic details remain to be discovered.

  18. Fluorescence properties of melanins from opioid peptides.

    PubMed

    Mosca, L; De Marco, C; Fontana, M; Rosei, M A

    1999-11-01

    Recently our group synthesized a new class of melanins obtained by the tyrosinase-catalyzed oxidation of opioid peptides (opiomelanins). Owing to the presence of the peptide moiety such pigments exhibit high solubility in hydrophilic solvents, which allows spectroscopic investigations. In particular, the absence of solid-state quenching effects enables the study of melanin fluorescence properties, till now poorly investigated due to the complete insolubility of melanins produced from tyrosine or Dopa. Opiomelanins dissolved in aqueous medium show a characteristic emission peaked at 440 and 520 nm when excited around 330 nm, where a maximum is observed in the absorption spectrum. Kinetic measurements performed on the tyrosinase-catalyzed oxidation of opioid peptides show that the 440-nm fluorescence band arises in the early stages of peptide oxidation, whereas the 520-nm band appears in later stages of oxidation, i.e., during the polymerization of indole-quinone units. Moreover, molecular sieve fractionation shows that in the opiomelanin fraction with a molecular weight lower than 10 kDa the 440-nm band is dominant in the fluorescence spectrum. The breakdown of the polymer induced by hydrogen peroxide and light (i.e., the photobleaching of melanin pigments) produces a marked enhancement of the 440-nm fluorescence band while the 520-nm band disappears. Hence, our findings suggest that the observed fluorescence contains contributions from both oligomeric units (440-nm band) and high-molecular-weight polymers (520-nm band).

  19. Chemical degradation of melanins: application to identification of dopamine-melanin.

    PubMed

    Ito, S; Wakamatsu, K

    1998-04-01

    Melanocytes produce two chemically distinct types of melanin pigments, eumelanins and pheomelanins. These pigments can be quantitatively analyzed by acidic KMnO4 oxidation or reductive hydrolysis with hydriodic acid (HI) to form pyrrole-2,3,5-tricarboxylic acid (PTCA) or aminohydroxyphenylalanine (AHP), respectively. Dark brown melanin-like pigments are also widespread in nature, for example, in the substantia nigra of humans and primates (neuromelanin), in butterfly wings and in the fungus Cryptococcus neoformans. To characterize such diverse types of melanins, we have improved the alkaline H2O2 oxidation method of Napolitano et al. (Tetrahedron, 51:5913-5920, 1995) and re-examined the HI hydrolysis method of Wakamatsu et al. (Neurosci. Lett., 131:57-60, 1991). The results obtained with H2O2 oxidation show that 1) pyrrole-2,3-dicarboxylic acid (PDCA), a specific marker of 5,6-dihydroxyindole units in melanins, is produced in yields ten times higher than by acidic KMnO4 oxidation, and 2) PTCA is artificially produced from pheomelanins. The results with HI hydrolysis show that dopamine-melanin produces a 1:1 mixture of 3-amino and 4-amino isomers of aminohydroxyphenylethylamine, while the isomer ratio is about 0.2 in melanins prepared from dopamine and cysteine. These results indicate that alkaline H2O2 oxidation is useful in characterizing synthetic and natural eumelanins and that reductive hydrolysis with HI can be applied to analyzing oxidation products of dopamine such as neuromelanin.

  20. Iron, melanin and dopamine interaction: relevance to Parkinson's disease.

    PubMed

    Ben-Shachar, D; Youdim, M B

    1993-01-01

    1. Interaction between iron and melanin may provide a reasonable explanation for the vulnerability of the melanin containing dopaminergic neurons in the substantia nigra (SN) to neurodegeneration in Parkinson's disease (PD). 2. Scatchard analysis of the binding of iron to synthetic dopamine melanin revealed a high-affinity (KD = 13 nM) and a lower affinity (KD = 200 nM) binding sites. 3. The binding of iron to melanin is dependent on the concentration of melanin and on pH. 4. Iron chelators, U74500A, desferrioxamine and to a lesser extent 1,10-phenanthroline and chlorpromazine could displace iron from melanin. In contrast, 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) and its metabolite 1-methyl-4-phenyl-pyridinium (MPP+), which cause Parkinsonism, were unable to displace iron. 5. Melanin alone reduced lipid peroxidation in rat cortical membrane preparations. However, iron induced lipid peroxidation, which could be inhibited by desferrioxamine, was potentiated by melanin. 6. Iron bound to neuromelanin in melanized dopamine neurons was detected only in parkinsonian brains and not in controls. The interaction of iron with neuromelanin as identified by x-ray defraction technique was identical to iron interaction with synthetic dopamine melanin. 7. In the absence of an identified exogenous or endogenous neurotoxin in idiopathic Parkinson's disease, iron-melanin interaction in the SN may serve as a candidate for the oxygen-radical induced neurodegeneration of the melanin containing dopaminergic neurons.

  1. Interaction of radicals from water radiolysis with melanin.

    PubMed

    Sarna, T; Pilas, B; Land, E J; Truscott, T G

    1986-08-06

    Melanins are considered to be natural photoprotectors in the melanocytes and keratinocytes of the skin. These pigments have also been suggested to play an important role in protection of melanin-containing cells against ionising radiation. Various mechanisms have been proposed to explain the protective role of melanin which invoke the radical scavenging properties of the polymer. In the present work the reactions of melanins with radicals generated in aqueous media by pulse radiolysis have been studied. Time-resolved changes in absorbance of the melanin or the radical species were recorded at selected wavelengths. Experiments were carried out on synthetic dopa- and 5-S-cysteinyldopa-melanins and a natural melanin in phosphate buffer (pH 7.4). Under the conditions employed, melanin reacted predominantly with either oxidising (OH., N3.) or reducing (eaq-, CO2-) species. We were also able to monitor the interaction of melanin with superoxide radical, which was reducing in this case. Detailed analysis of transient changes in melanin absorbance, detected at different wavelengths, was demonstrated to be a convenient method for studying redox processes of this substance, as shown by model experiments using ferricyanide and dithionite as oxidising and reducing agents, respectively. Among the radicals studied, OH. exhibited the strongest reactivity with melanins. Apparent rate constants for the reactions of radicals with autoxidative dopa-melanin (1.5 X 10(9) M-1 X s-1, 2.6 X 10(8) M-1 X s-1, 1.8 X 10(8) M-1 X s-1, 5 X 10(5) M-1 X s-1, 10(6)-10(7) M-1 X s-1 for OH., eaq-, N.3. O2- and CO2-, respectively) are reported. The reactivity of melanins with radicals from water radiolysis and their effect on pigment properties are discussed in terms of the structure and possible biological role of the pigments.

  2. Activation of the Alternative Complement Pathway by Fungal Melanins

    PubMed Central

    Rosas, Á. L.; MacGill, R. S.; Nosanchuk, J. D.; Kozel, T. R.; Casadevall, A.

    2002-01-01

    Melanins are complex biological pigments formed by the oxidative polymerization of phenolic and/or indolic compounds. These pigments have been implicated in the pathogenesis of some microbial infections, malignancies, degenerative disorders, and autoimmune diseases. Recent studies have demonstrated that melanins have antigenic and anti-inflammatory properties. These findings led us to further explore the interaction of melanins with the immune system. Melanin particles (“ghosts”) were isolated from in vitro-melanized Cryptococcus neoformans cells and Aspergillus niger conidia and then incubated in normal human serum containing 125I-labeled complement C3. The results demonstrated deposition of C3 fragments onto the melanin ghosts as early as 1 min after incubation, with maximum deposition occurring after 12 min for C. neoformans-derived melanin ghosts and after 25 min for A. niger-derived melanin ghosts. The blocking of classical pathway activation did not affect the kinetics or total deposition of C3 onto the melanin ghosts, indicating that melanins activate complement through the alternative pathway. Immunofluorescence analysis of lungs from BALB/c mice injected intratracheally with C. neoformans-derived melanin ghosts demonstrated deposition of C3 fragments onto the ghosts. Small granulomas were also observed surrounding the ghosts. However, melanization of the C. neoformans cell wall did not alter the kinetics or total deposition of C3 fragments onto the fungal cells. The finding that melanin surfaces can activate the complement system suggests a potential mechanism for the pathogenesis of some degenerative and/or autoimmune processes that involve melanized cells as well as another potential role for melanin in the virulence of melanin-producing microorganisms. PMID:11777844

  3. Melanins and melanogenesis: methods, standards, protocols.

    PubMed

    d'Ischia, Marco; Wakamatsu, Kazumasa; Napolitano, Alessandra; Briganti, Stefania; Garcia-Borron, José-Carlos; Kovacs, Daniela; Meredith, Paul; Pezzella, Alessandro; Picardo, Mauro; Sarna, Tadeusz; Simon, John D; Ito, Shosuke

    2013-09-01

    Despite considerable advances in the past decade, melanin research still suffers from the lack of universally accepted and shared nomenclature, methodologies, and structural models. This paper stems from the joint efforts of chemists, biochemists, physicists, biologists, and physicians with recognized and consolidated expertise in the field of melanins and melanogenesis, who critically reviewed and experimentally revisited methods, standards, and protocols to provide for the first time a consensus set of recommended procedures to be adopted and shared by researchers involved in pigment cell research. The aim of the paper was to define an unprecedented frame of reference built on cutting-edge knowledge and state-of-the-art methodology, to enable reliable comparison of results among laboratories and new progress in the field based on standardized methods and shared information.

  4. Bioinspired bright noniridescent photonic melanin supraballs

    PubMed Central

    Xiao, Ming; Hu, Ziying; Wang, Zhao; Li, Yiwen; Tormo, Alejandro Diaz; Le Thomas, Nicolas; Wang, Boxiang; Gianneschi, Nathan C.; Shawkey, Matthew D.; Dhinojwala, Ali

    2017-01-01

    Structural colors enable the creation of a spectrum of nonfading colors without pigments, potentially replacing toxic metal oxides and conjugated organic pigments. However, significant challenges remain to achieve the contrast needed for a complete gamut of colors and a scalable process for industrial application. We demonstrate a feasible solution for producing structural colors inspired by bird feathers. We have designed core-shell nanoparticles using high–refractive index (RI) (~1.74) melanin cores and low-RI (~1.45) silica shells. The design of these nanoparticles was guided by finite-difference time-domain simulations. These nanoparticles were self-assembled using a one-pot reverse emulsion process, which resulted in bright and noniridescent supraballs. With the combination of only two ingredients, synthetic melanin and silica, we can generate a full spectrum of colors. These supraballs could be directly added to paints, plastics, and coatings and also used as ultraviolet-resistant inks or cosmetics. PMID:28929137

  5. Bioinspired bright noniridescent photonic melanin supraballs.

    PubMed

    Xiao, Ming; Hu, Ziying; Wang, Zhao; Li, Yiwen; Tormo, Alejandro Diaz; Le Thomas, Nicolas; Wang, Boxiang; Gianneschi, Nathan C; Shawkey, Matthew D; Dhinojwala, Ali

    2017-09-01

    Structural colors enable the creation of a spectrum of nonfading colors without pigments, potentially replacing toxic metal oxides and conjugated organic pigments. However, significant challenges remain to achieve the contrast needed for a complete gamut of colors and a scalable process for industrial application. We demonstrate a feasible solution for producing structural colors inspired by bird feathers. We have designed core-shell nanoparticles using high-refractive index (RI) (~1.74) melanin cores and low-RI (~1.45) silica shells. The design of these nanoparticles was guided by finite-difference time-domain simulations. These nanoparticles were self-assembled using a one-pot reverse emulsion process, which resulted in bright and noniridescent supraballs. With the combination of only two ingredients, synthetic melanin and silica, we can generate a full spectrum of colors. These supraballs could be directly added to paints, plastics, and coatings and also used as ultraviolet-resistant inks or cosmetics.

  6. Dopamine-melanin nanofilms for biomimetic structural coloration.

    PubMed

    Wu, Tong-Fei; Hong, Jong-Dal

    2015-02-09

    This article describes the formation of dopamine-melanin thin films (50-200 nm thick) at an air/dopamine solution interface under static conditions. Beneath these films, spherical melanin granules formed in bulk liquid phase. The thickness of dopamine-melanin films at the interface relied mainly on the concentration of dopamine solution and the reaction time. A plausible mechanism underlining dopamine-melanin thin film formation was proposed based on the hydrophobicity of dopamine-melanin aggregates and the mass transport of the aggregates to the air/solution interface as a result of convective flow. The thickness of the interfacial films increased linearly with the dopamine concentration and the reaction time. The dopamine-melanin thin film and granules (formed in bulk liquid phase) with a double-layered structure were transferred onto a solid substrate to mimic the (keratin layer)/(melanin granules) structure present in bird plumage, thereby preparing full dopamine-melanin thin-film reflectors. The reflected color of the thin-film reflectors depended on the film thickness, which could be adjusted according to the dopamine concentration. The reflectance of the resulted reflectors exhibited a maximal reflectance value of 8-11%, comparable to that of bird plumage (∼11%). This study provides a useful, simple, and low-cost approach to the fabrication of biomimetic thin-film reflectors using full dopamine-melanin materials.

  7. Extracellular and intracellular melanin in inflammatory middle ear disease.

    PubMed

    Fritz, Mark A; Roehm, Pamela C; Bannan, Michael A; Lalwani, Anil K

    2014-06-01

    Melanin is a pigmented polymer with a known role in dermal solar protection. In vertebrates, melanogenesis has been reported in leukocyte populations, suggesting a potential role in innate immunity. In this study, we report the novel finding of melanin associated with chronic inflammation and speculate on its potential role in the middle ear and mastoid. Retrospective review of case series. Medical records of six patients who demonstrated melanin in the ear were reviewed. Six patients from 1 to 63 years of age were identified with extracellular melanin and melanin-laden histiocytes within the middle ear and/or mastoid air cells at time of surgery. Concurrent intraoperative findings included cholesteatoma (n = 3), chronic suppurative otitis media (n = 2), and coalescent mastoiditis (n = 1). Histologically, extracellular melanin and melanin-laden histiocytes were identified by Fontana-Masson stain; absence of melanocytes was confirmed by the absence of Melan-A staining. One patient had a positive stain for CD163 (a marker for macrophages). This case series is the first demonstration of melanin within middle ear mucosa without melanocytes in immediate proximity or metastatic melanocytic lesions. Melanin's presence in the setting of inflammation suggests that there may be a heretofore unreported link between the pigmentary and immune systems in the middle ear. 4.

  8. Spectroscopic features of native and bleached opio-melanins.

    PubMed

    Rosei, M A; Mosca, L; De Marco, C

    1995-01-18

    Opioid peptides can be converted by tyrosinase into melanin-like compounds, in which the peptide moiety is retained. Such pigments, named opio-melanins, exhibit a characteristic absorption spectrum with a maximum at about 330 nm and a different solubility behaviour with respect to dopa-melanin, being completely soluble in hydrophylic solvents at neutral and basic pH. Opio-melanins precipitate in aqueous solutions below pH 5.0, and show apparent pKa values of 3.1, 3.6 and 4.4 for Tyr-Gly-melanin, Tyr-Gly-Gly-melanin and leuenk-melanin, respectively. The concomitant oxidation of dopa and opioid peptides by tyrosinase produces mixed polymers, showing the distinctive absorption peak at 330 nm. In the dark, in the pH range 5.5-7.0 the pigments are completely stable, whereas H2O2 addition provokes a slight degradation. At higher pH values or under simulated solar illumination with or without hydrogen peroxide, bleaching occurs more rapidly than in dopa-melanin. Upon photoirradiation the absorption spectrum of opio-melanins undergoes a marked variation, the peak at 330 nm being replaced by a broad shoulder in the range 280-350 nm. The absorption spectra of native and bleached pigments and the extent of opio-melanins degradation by bleaching agents, confirm the hypothesis that the different initial structure of the precursors accounts for a final diverse polymeric architecture of these pigments with respect to dopa-melanin.

  9. Renal excretion of plasma soluble melanins by healthy human adults.

    PubMed

    Hegedus, Z L; Nayak, U

    1993-01-01

    The soluble melanins of blood plasma form in vivo and in vitro from dopa, catecholamines, catechol, hydroquinone, homogentisic acid, 3-hydroxykynurenine, 3-hydroxyanthranilic acid, p-aminophenol, p-phenylenediamine and other structurally related end(ex)ogenous compounds by oxidative polymerization. The mean quantity of natural melanins in normal plasma is 1.61 +/- 0.10 (standard deviation) mg/ml, (n = 20) and in uraemic plasma 2.72 +/- 0.38 mg/ml, (n = 16). The plasma melanins (approximately 3%), are associated with proteins (approximately 85%), mucoproteins (approximately 0.25%), lipids (approximately 0.4%), as soluble lipofuscins, and probably are associated with proteins without lipids as soluble melanoproteins. Fluorescence, UV-VIS and IR spectroscopies and the melanin isolation method show the presence of soluble melanins in the urine of healthy people. Soluble melanins can also be formed in vitro in the urine by oxidative polymerization of the precursors. In most of the urine samples we studied, melanins were present in larger amounts than the urinary proteins, indicating that the kidneys can selectively excrete the melanin components of the lipofuscins, and that the solubility of melanins does not depend upon combination with proteins. The quantities of purified melanins precipitated with 6 N HCl at 110 degrees C during 72 h from urine samples collected during 24 h periods ranged from 0.1460 g to 3.7627 g (mean 1.1303 +/- 1.1739 g, n = 8) and the plasma clearance rates ranged from 0.06 ml/min to 1.56 ml/min (mean 0.48 +/- 0.48 ml/min, n = 8). From the individual 24 h urine samples we obtained from 9 to 216 mg/dl of precipitated melanins while the individual plasma samples contained from 145 to 175 mg/dl.

  10. In vivo stepwise multi-photon activation fluorescence imaging of melanin in human skin

    NASA Astrophysics Data System (ADS)

    Lai, Zhenhua; Gu, Zetong; Abbas, Saleh; Lowe, Jared; Sierra, Heidy; Rajadhyaksha, Milind; DiMarzio, Charles

    2014-03-01

    The stepwise multi-photon activated fluorescence (SMPAF) of melanin is a low cost and reliable method of detecting melanin because the activation and excitation can be a continuous-wave (CW) mode near infrared (NIR) laser. Our previous work has demonstrated the melanin SMPAF images in sepia melanin, mouse hair, and mouse skin. In this study, we show the feasibility of using SMPAF to detect melanin in vivo. in vivo melanin SMPAF images of normal skin and benign nevus are demonstrated. SMPAF images add specificity for melanin detection than MPFM images and CRM images. Melanin SMPAF is a promising technology to enable early detection of melanoma for dermatologists.

  11. Melanin content of hamster tissues, human tissues, and various melanomas

    SciTech Connect

    Watts, K.P.; Fairchild, R.G.; Slatkin, D.N.; Greenberg, D.; Packer, S.; Atkins, H.L.; Hannon, S.J.

    1981-02-01

    Melanin content (percentage by weight) was determined in both pigmented and nonpigmented tissues of Syrian golden hamsters bearing Greene melanoma. Melanin content was also measured in various other melanoma models (B-16 in C57 mice, Harding-Passey in BALB/c mice, and KHDD in C3H mice) and in nine human melanomas, as well as in selected normal tissues. The purpose was to evaluate the possible efficacy of chlorpromazine, which is known to bind to melanin, as a vehicle for boron transport in neutron capture therapy. Successful therapy would depend upon selective uptake and absolute concentration of borated compounds in tumors; these parameters will in turn depend upon melanin concentration in melanomas and nonpigmented ''background'' tissues. Hamster whole eyes, hamster melanomas, and other well-pigmented animal melanomas were found to contain 0.3 to 0.8% melanin by weight, whereas human melanomas varied from 0.1 to 0.9% (average, 0.35%). Other tissues, with the exception of skin, were lower in content by a factor of greater than or equal to30. Melanin pigment was extracted from tissues, and the melanin content was determined spectrophotometrically. Measurements were found to be sensitive to the presence of other proteins. Previous procedures for isolating and quantifying melanin often neglected the importance of removing proteins and other interfering nonmelanic substances.

  12. Superior Performance of Polyurethane Based on Natural Melanin Nanoparticles.

    PubMed

    Wang, Yang; Li, Ting; Wang, Xuefei; Ma, Piming; Bai, Huiyu; Dong, Weifu; Xie, Yi; Chen, Mingqing

    2016-11-14

    Melanin, a kind of well-known multifunctional biomacromolecules that are widely distributed in natural sources. In this work, polyurethane (PU)/melanin nanocomposites with enhanced tensile strength and toughness were successfully fabricated via in situ polymerization. It was found that the tensile strength (σ), elongation-at-break (εmax), and toughness (W) were improved from 5.6 MPa, 770%, and 33 MJ/m(3) for PU to 51.5 MPa, 1880%, and 413 MJ/m(3) for PU/melanin (2 wt %) nanocomposite, respectively. Micromorphology indicated that individualized melanin nanoparticles were specifically linked to the hard domains of PU chains and fine dispersed in matrix. FTIR, DSC, and AFM results suggested melanin induced an improvement in degree of phase separation, which resulted in remarkable enhancements in mechanical properties of PU. However, with further increasing content of melanin, a relatively large-scale phase separation was formed and led to a decrease in mechanical properties of PU. In addition, interactions between melanin and hard segments of PU were increased, leading to a higher TgHS. Moreover, the dynamic mechanical properties and rheological behavior of PU/melanin nanocomposites were further investigated.

  13. The use of spectrophotometry to estimate melanin density in Caucasians.

    PubMed

    Dwyer, T; Muller, H K; Blizzard, L; Ashbolt, R; Phillips, G

    1998-03-01

    The density of cutaneous melanin may be the property of the skin that protects it from damage by solar radiation, but there is not an accepted, noninvasive method of measuring it. To determine whether the density of cutaneous melanin can be estimated from reflectance of visible light by the skin, reflectance of 15-nm wavebands of light by the skin of the inner upper arm of each of 82 volunteers was measured at 20-nm intervals with a Minolta 508 spectrophotometer. A 3-mm skin biopsy was then taken from the same site, and four nonserial sections of it were stained with Masson Fontana for melanin. The melanin content of the basal area was calculated using the NIH Image analysis system. We show that cutaneous melanin in Caucasians can be estimated by the difference between two measurements of reflectance of visible light by the skin: those at wavelengths 400 and 420 nm. This new spectrophotometric measurement was more highly correlated (r = 0.68) with the histological measurements of cutaneous melanin than was skin reflectance of light of wavelength 680 nm (r = 0.33). Reflectances in the range of 650-700 nm have been used previously in skin cancer research. This relatively accurate measurement of melanin is quick and noninvasive and can be readily used in the field. It should provide improved discrimination of individual susceptibility to epidermal tumors in Caucasians and information about melanin's biological role in the causation of skin cancer.

  14. A hypothetical structure of melanin and its relation to biology.

    PubMed

    Strzelecka, T

    1982-01-01

    Measurements of optical absorption of synthetic and natural melanins during their degradation in sodium hydroxide establish that from the "optical" point of view these polymers consist of two different parts. An explanation of this result and its possible relation to the biological role of melanin is given.

  15. Temperature-enhanced synthesis of DMSO-Melanin

    NASA Astrophysics Data System (ADS)

    Piacenti-Silva, M.; Bronze-Uhle, E. S.; Paulin, J. V.; Graeff, C. F. O.

    2014-01-01

    Melanins are a class of pigmentary conjugated macromolecules found in many biological systems. Functionalization of synthetic melanin provides interesting new properties like the greater solubility of melanin synthesized in dimethyl sulfoxide, D-Melanin. In this work we have studied the influence of temperature on D-Melanin synthesis and its properties. To this end, UV-Vis, Fourier-transform infrared (FTIR) spectroscopy and Nuclear Magnetic Resonance (NMR) techniques have been employed to analyze D-Melanin synthesized within the range of 25-100 °C. Our results reveal that by increasing the synthesis temperature up to 100 °C, the synthesis time can be decreased by a factor of 7 when compared to room temperature. From FTIR and 13C CP/MAS NMR analyses the increase in temperature causes a decrease in the number of carbonyl groups from carboxylic acid and from ionized carboxylic acid. The decarboxylation of D-Melanin monomers at higher temperatures shows that the use of higher synthesis temperatures influences the elimination of carbonyls present in the precursor molecules, thus facilitating the polymerization of D-Melanin.

  16. Anti-melanin deposition activity of ceramicines from Chisocheton ceramicus.

    PubMed

    Iijima, Chie; Wong, Chin Piow; Nugroho, Alfarius Eko; Sotozono, Yayoi; Someya, Saki; Hirasawa, Yusuke; Kaneda, Toshio; Hadi, A Hamid A; Morita, Hiroshi

    2016-10-01

    The ceramicines, a series of limonoids from Chisocheton ceramicus (Meliaceae), were evaluated for anti-melanin deposition activity on α-melanocyte stimulating hormone (α-MSH) and 3-isobutyl-1-methylxanthine (IBMX)-treated B16-F10 melanoma cell, and several ceramicines were found to be active. The structure-activity relationship of ceramicines as anti-melanin deposition inhibitors was deduced. Furthermore, the mechanism of anti-melanin deposition activity of ceramicine B, a major constituent of C. ceramicus that showed potent anti-melanin deposition activity, was investigated. Tyrosinase enzymatic activity and tyrosinase mRNA expression were not affected by ceramicine B. The anti-melanin deposition activity of ceramicine B was shown to be related to the downregulation of tyrosinase protein expression. These results suggest that ceramicines have potential to be used as depigmentation agents.

  17. Electronic structure calculations of ESR parameters of melanin units.

    PubMed

    Batagin-Neto, Augusto; Bronze-Uhle, Erika Soares; Graeff, Carlos Frederico de Oliveira

    2015-03-21

    Melanins represent an important class of natural pigments present in plants and animals that are currently considered to be promising materials for applications in optic and electronic devices. Despite their interesting properties, some of the basic features of melanins are not satisfactorily understood, including the origin of their intrinsic paramagnetism. A number of experiments have been performed to investigate the electron spin resonance (ESR) response of melanin derivatives, but until now, there has been no consensus regarding the real structure of the paramagnetic centers involved. In this work, we have employed electronic structure calculations to evaluate the ESR parameters of distinct melanin monomers and dimers in order to identify the possible structures associated with unpaired spins in this biopolymer. The g-factors and hyperfine constants of the cationic, anionic and radicalar structures were investigated. The results confirm the existence of at least two distinct paramagnetic centers in melanin structure, identifying the chemical species associated with them and their roles in electrical conductivity.

  18. Natural melanin composites by layer-by-layer assembly

    NASA Astrophysics Data System (ADS)

    Eom, Taesik; Shim, Bong Sub

    2015-04-01

    Melanin is an electrically conductive and biocompatible material, because their conjugated backbone structures provide conducting pathways from human skin, eyes, brain, and beyond. So there is a potential of using as materials for the neural interfaces and the implantable devices. Extracted from Sepia officinalis ink, our natural melanin was uniformly dispersed in mostly polar solvents such as water and alcohols. Then, the dispersed melanin was further fabricated to nano-thin layered composites by the layer-by-layer (LBL) assembly technique. Combined with polyvinyl alcohol (PVA), the melanin nanoparticles behave as an LBL counterpart to from finely tuned nanostructured films. The LBL process can adjust the smart performances of the composites by varying the layering conditions and sandwich thickness. We further demonstrated the melanin loading degree of stacked layers, combination nanostructures, electrical properties, and biocompatibility of the resulting composites by UV-vis spectrophotometer, scanning electron microscope (SEM), multimeter, and in-vitro cell test of PC12, respectively.

  19. Optical properties of melanin in the skin and skinlike phantoms

    NASA Astrophysics Data System (ADS)

    Bashkatov, Alexey N.; Genina, Elina A.; Kochubey, Vyacheslav I.; Stolnitz, Mikhail M.; Bashkatova, Tatyana A.; Novikova, Olga V.; Peshkova, Anna Y.; Tuchin, Valery V.

    2000-11-01

    Experimental study and computer modeling were used to investigate the optical properties of melanin in the skin and skin-like phantoms. To investigate light scattering by melanosomes in skin we made skin-like phantoms on the base of gelatin with different content of melanin particles. Spectra of total transmittance and diffuse reflectance of the phantoms were obtained in the wavelength range from 400 to 800 nm. Absorption and reduced scattering coefficients of melanin were calculated. Mie theory was used to estimate the optical properties of melanin particles. Wavelength dependence of refractive indices of eumelanin particles (isolated and purified from the ink of the cuttlefish Sepia officinalis) and synthetic melanin particles was estimated.

  20. Matrix assisted pulsed laser deposition of melanin thin films

    NASA Astrophysics Data System (ADS)

    Bloisi, F.; Pezzella, A.; Barra, M.; Chiarella, F.; Cassinese, A.; Vicari, L.

    2011-07-01

    Melanins constitute a very important class of organic pigments, recently emerging as a potential material for a new generation of bioinspired biocompatible electrically active devices. In this paper, we report about the deposition of synthetic melanin films starting from aqueous suspensions by matrix assisted pulsed laser evaporation (MAPLE). In particular, we demonstrate that it is possible to deposit melanin films by MAPLE even if melanin (a) is not soluble in water and (b) absorbs light from UV to IR. AFM images reveal that the film surface features are highly depending on the deposition parameters. UV-VIS and FTIR spectra show both the optical properties and the molecular structure typical of melanins are preserved.

  1. Melanin-templated rapid synthesis of silver nanostructures

    PubMed Central

    2014-01-01

    Background As a potent antimicrobial agent, silver nanostructures have been used in nanosensors and nanomaterial-based assays for the detection of food relevant analytes such as organic molecules, aroma, chemical contaminants, gases and food borne pathogens. In addition silver based nanocomposites act as an antimicrobial for food packaging materials. In this prospective, the food grade melanin pigment extracted from sponge associated actinobacterium Nocardiopsis alba MSA10 and melanin mediated synthesis of silver nanostructures were studied. Based on the present findings, antimicrobial nanostructures can be developed against food pathogens for food industrial applications. Results Briefly, the sponge associated actinobacterium N. alba MSA10 was screened and fermentation conditions were optimized for the production of melanin pigment. The Plackett-Burman design followed by a Box-Behnken design was developed to optimize the concentration of most significant factors for improved melanin yield. The antioxidant potential, reductive capabilities and physiochemical properties of Nocardiopsis melanin was characterized. The optimum production of melanin was attained with pH 7.5, temperature 35°C, salinity 2.5%, sucrose 25 g/L and tyrosine 12.5 g/L under submerged fermentation conditions. A highest melanin production of 3.4 mg/ml was reached with the optimization using Box-Behnken design. The purified melanin showed rapid reduction and stabilization of silver nanostructures. The melanin mediated process produced uniform and stable silver nanostructures with broad spectrum antimicrobial activity against food pathogens. Conclusions The melanin pigment produced by N. alba MSA10 can be used for environmentally benign synthesis of silver nanostructures and can be useful for food packaging materials. The characteristics of broad spectrum of activity against food pathogens of silver nanostructures gives an insight for their potential applicability in incorporation of food

  2. Melanin-templated rapid synthesis of silver nanostructures.

    PubMed

    Kiran, George Seghal; Dhasayan, Asha; Lipton, Anuj Nishanth; Selvin, Joseph; Arasu, Mariadhas Valan; Al-Dhabi, Naif Abdullah

    2014-05-01

    As a potent antimicrobial agent, silver nanostructures have been used in nanosensors and nanomaterial-based assays for the detection of food relevant analytes such as organic molecules, aroma, chemical contaminants, gases and food borne pathogens. In addition silver based nanocomposites act as an antimicrobial for food packaging materials. In this prospective, the food grade melanin pigment extracted from sponge associated actinobacterium Nocardiopsis alba MSA10 and melanin mediated synthesis of silver nanostructures were studied. Based on the present findings, antimicrobial nanostructures can be developed against food pathogens for food industrial applications. Briefly, the sponge associated actinobacterium N. alba MSA10 was screened and fermentation conditions were optimized for the production of melanin pigment. The Plackett-Burman design followed by a Box-Behnken design was developed to optimize the concentration of most significant factors for improved melanin yield. The antioxidant potential, reductive capabilities and physiochemical properties of Nocardiopsis melanin was characterized. The optimum production of melanin was attained with pH 7.5, temperature 35°C, salinity 2.5%, sucrose 25 g/L and tyrosine 12.5 g/L under submerged fermentation conditions. A highest melanin production of 3.4 mg/ml was reached with the optimization using Box-Behnken design. The purified melanin showed rapid reduction and stabilization of silver nanostructures. The melanin mediated process produced uniform and stable silver nanostructures with broad spectrum antimicrobial activity against food pathogens. The melanin pigment produced by N. alba MSA10 can be used for environmentally benign synthesis of silver nanostructures and can be useful for food packaging materials. The characteristics of broad spectrum of activity against food pathogens of silver nanostructures gives an insight for their potential applicability in incorporation of food packaging materials and

  3. Link between facultative melanin and tobacco use among African Americans.

    PubMed

    King, Gary; Yerger, Valerie B; Whembolua, Guy-Lucien; Bendel, Robert B; Kittles, Rick; Moolchan, Eric T

    2009-06-01

    Nicotine's affinity for melanin-containing tissues may result from its precursor function in melanin synthesis or the irreversible binding of melanin and nicotine. The objective of this study was to investigate a hypothesized association of tobacco use, dependence, and nicotine exposure with melanin pigmentation among African American smokers. A criterion-based sample was employed to collect data from a study of 147 adult African American current smokers. Carbon monoxide, saliva cotinine samples, and skin reflectance measures were obtained from each participant. Questionnaire data on demographic, sociological and behavioral questions related to smoking and skin color were gathered. The three dependent measures were the average number of cigarettes per day (CPD), Fagerström Test of Nicotine Dependence (FTND) score, and cotinine concentration. Analysis of variance, Pearson Correlations, and Multiple Linear Regression were conducted to analyze findings. The mean constitutive melanin reading was 56.3 and 66.5 for facultative melanin. Respondents on average smoked 19 CPD, had a mean FTND of 5.6, and a cotinine concentration of 435 ng/ml. Facultative melanin level was correlated with CPD and cotinine concentration in the bivariate analysis. The multiple linear regression results revealed that facultative melanin was significantly and positively related to CPD, the FTND, and cotinine. The results of this analysis support the hypothesis of a positive association between melanin levels and tobacco use, dependence, and exposure among African American smokers. This analysis may have important implications for research and interventions on tobacco dependence and disease outcomes. Further research on melanin and nicotine among African Americans as well as other population groups is warranted.

  4. Experimental melanin-protein induced uveitis (EMIU) is the sole type of uveitis evoked by a diversity of ocular melanin preparations and melanin-derived soluble polypeptides.

    PubMed

    Broekhuyse, R M; Kuhlmann, E D; Winkens, H J

    1996-01-01

    Experimental melanin-protein induced uveitis (EMIU) is a CD4 T cell-mediated disease involving the choroid and iris, but sparing the retina. The present study was designed to solubilize uveitogenic antigen from melanin granules without enzymatic digestion, and to investigate some of its elements by comparison with different purified melanin preparations. Many melanin surface-derived polypeptides with molecular weights ranging from 1 to > 100 kDa were obtained by extractions of the prepurified granules with hot lithium dodecyl sulfate (LDS). The mixture was electrophoretically separated into seven subfractions, each containing many components and capable of evoking the typical features of EMIU after footpad immunization of Lewis rats. The five low-molecular-weight fractions between M, 1 kDa and 30 kDa exhibited most pathogenicity which was evenly distributed among the fractions. Highly uveitogenic material remained in the melanin preparations even after multiple exhaustive extractions with LDS, and represented about 70% of the detectable protein. The uveal pathogen (UP-X) thus proved to be antigenically stable, and the major part of the pathogenic material was strongly bound to the granule surface layer. Concentrated urea solution was also capable of extracting many uveitogenic melanin polypeptides, but in a different composition than LDS did, and less effectively. Human choroidal melanin provided an LDS-soluble fraction with low pathogenicity. A single intraperitoneal injection of bovine melanin polypeptides together with pertussis toxin, but without footpad immunization in Freund's complete adjuvant, evoked EMIU as well. In all experiments, no uveitis except EMIU was observed, indicating that only one type of uveitogenic epitope was present in a wide variety of carrier molecules. An explanation for this phenomenon is discussed.

  5. Binding of betaxolol, metoprolol and oligonucleotides to synthetic and bovine ocular melanin, and prediction of drug binding to melanin in human choroid-retinal pigment epithelium.

    PubMed

    Pitkänen, Leena; Ranta, Veli-Pekka; Moilanen, Hanna; Urtti, Arto

    2007-11-01

    To characterize the binding of betaxolol, metoprolol and oligonucleotides to synthetic and bovine ocular melanin, and to predict the binding to melanin in human choroid-retinal pigment epithelium (RPE). The shape, size and specific surface area of synthetic melanin and isolated melanin granules from bovine choroid-retinal pigment epithelium (RPE) were characterized by SEM, laser diffractometry and BET. The binding of betaxolol, metoprolol, fluorescein isothiocyanate (FITC)-labeled phosphodiesther oligonucleotides and 6-carboxyfluorescein (6-CF) to melanin was determined. The binding of beta-blockers to melanin in human choroid-RPE was estimated based on binding parameters and the melanin content in human choroid-RPE. Bovine melanin granules were round or oval with a mean diameter of ca. 1 mum. Synthetic granules were slightly smaller and irregular and had a two times higher specific surface area than bovine melanin. Synthetic melanin bound more betaxolol and metoprolol than bovine melanin and both melanin types showed a high affinity and a low affinity binding sites. The human choroid-RPE was predicted to contain 3-19 times more melanin bound drug than unbound drug at typical therapeutic concentrations (1-1,000 ng/ml). FITC-labeled oligonucleotides and 6-CF did not bind to melanin. The binding of lipophilic drugs to biological melanin differs from that of synthetic melanin. Lipophilic beta-blockers are expected to bind significantly to melanin in human choroid-RPE: only a small fraction of the drug being in active free form. In contrast, phosphodiesther oligonucleotides do not seem to bind to melanin.

  6. Activation of Melanin Synthesis in Alternaria infectoria by Antifungal Drugs.

    PubMed

    Fernandes, Chantal; Prados-Rosales, Rafael; Silva, Branca M A; Nakouzi-Naranjo, Antonio; Zuzarte, Mónica; Chatterjee, Subhasish; Stark, Ruth E; Casadevall, Arturo; Gonçalves, Teresa

    2015-12-28

    The importance of Alternaria species fungi to human health ranges from their role as etiological agents of serious infections with poor prognoses in immunosuppressed individuals to their association with respiratory allergic diseases. The present work focuses on Alternaria infectoria, which was used as a model organism of the genus, and was designed to unravel melanin production in response to antifungals. After we characterized the pigment produced by A. infectoria, we studied the dynamics of 1,8-dihydroxynaphthalene (DHN)-melanin production during growth, the degree of melanization in response to antifungals, and how melanization affected susceptibility to several classes of therapeutic drugs. We demonstrate that A. infectoria increased melanin deposition in cell walls in response to nikkomycin Z, caspofungin, and itraconazole but not in response to fluconazole or amphotericin B. These results indicate that A. infectoria activates DHN-melanin synthesis in response to certain antifungal drugs, possibly as a protective mechanism against these drugs. Inhibition of DHN-melanin synthesis by pyroquilon resulted in a lower minimum effective concentration (MEC) of caspofungin and enhanced morphological changes (increased hyphal balloon size), characterized by thinner and less organized A. infectoria cell walls. In summary, A. infectoria synthesizes melanin in response to certain antifungal drugs, and its susceptibility is influenced by melanization, suggesting the therapeutic potential of drug combinations that affect melanin synthesis.

  7. Melanin in Fonsecaea pedrosoi: a trap for oxidative radicals

    PubMed Central

    2010-01-01

    Background The pathogenic fungus Fonsecaea pedrosoi constitutively produces the pigment melanin, an important virulence factor in fungi. Melanin is incorporated in the cell wall structure and provides chemical and physical protection for the fungus. We evaluated the production of nitric oxide (NO) in macrophages, the oxidative burst and the inducible nitric oxide synthase (i-NOS) activity in interactions between activated murine macrophages and F. pedrosoi. Experiments were carried out with or without tricyclazole (TC) treatment, a selective inhibitor of the dihydroxynaphthalene (DHN)-melanin biosynthesis pathway in F. pedrosoi. The paramagnetisms of melanin and the TC-melanin were analysed by electron spin resonance. The fungal growth responses to H2O2 and to S-nitroso-N-acetylpenicillamine (SNAP), a nitric oxide donor, were also evaluated. Results Melanised F. pedrosoi cells were more resistant to both H2O2 and NO. Nitrite was not detected in the supernatant of macrophages incubated with melanised fungal cells. However, i-NOS expression was unaffected by the presence of either untreated control F. pedrosoi or TC-treated F. pedrosoi. In addition, the inhibition of the DHN-melanin pathway by TC improved the oxidative burst capability of the macrophages. Conclusion The NO-trapping ability of F. pedrosoi melanin is an important mechanism to escape the oxidative burst of macrophages. PMID:20233438

  8. Activation of Melanin Synthesis in Alternaria infectoria by Antifungal Drugs

    PubMed Central

    Fernandes, Chantal; Prados-Rosales, Rafael; Silva, Branca M. A.; Nakouzi-Naranjo, Antonio; Zuzarte, Mónica; Chatterjee, Subhasish; Stark, Ruth E.; Casadevall, Arturo

    2015-01-01

    The importance of Alternaria species fungi to human health ranges from their role as etiological agents of serious infections with poor prognoses in immunosuppressed individuals to their association with respiratory allergic diseases. The present work focuses on Alternaria infectoria, which was used as a model organism of the genus, and was designed to unravel melanin production in response to antifungals. After we characterized the pigment produced by A. infectoria, we studied the dynamics of 1,8-dihydroxynaphthalene (DHN)-melanin production during growth, the degree of melanization in response to antifungals, and how melanization affected susceptibility to several classes of therapeutic drugs. We demonstrate that A. infectoria increased melanin deposition in cell walls in response to nikkomycin Z, caspofungin, and itraconazole but not in response to fluconazole or amphotericin B. These results indicate that A. infectoria activates DHN-melanin synthesis in response to certain antifungal drugs, possibly as a protective mechanism against these drugs. Inhibition of DHN-melanin synthesis by pyroquilon resulted in a lower minimum effective concentration (MEC) of caspofungin and enhanced morphological changes (increased hyphal balloon size), characterized by thinner and less organized A. infectoria cell walls. In summary, A. infectoria synthesizes melanin in response to certain antifungal drugs, and its susceptibility is influenced by melanization, suggesting the therapeutic potential of drug combinations that affect melanin synthesis. PMID:26711773

  9. A Pathway Analysis of Melanin Patterning in a Hemimetabolous Insect.

    PubMed

    Liu, Jin; Lemonds, Thomas R; Marden, James H; Popadić, Aleksandar

    2016-05-01

    Diversity in insect pigmentation, encompassing a wide range of colors and spatial patterns, is among the most noticeable features distinguishing species, individuals, and body regions within individuals. In holometabolous species, a significant portion of such diversity can be attributed to the melanin synthesis genes, but this has not been formally assessed in more basal insect lineages. Here we provide a comprehensive analysis of how a set of melanin genes (ebony, black, aaNAT, yellow, and tan) contributes to the pigmentation pattern in a hemipteran, Oncopeltus fasciatus For all five genes, RNA interference depletion caused alteration of black patterning in a region-specific fashion. Furthermore, the presence of distinct nonblack regions in forewings and hindwings coincides with the expression of ebony and aaNAT in these appendages. These findings suggest that the region-specific phenotypes arise from regional employment of various combinations of the melanin genes. Based on this insight, we suggest that melanin genes are used in two distinct ways: a "painting" mode, using predominantly melanin-promoting factors in areas that generally lack black coloration, and, alternatively, an "erasing" mode, using mainly melanin-suppressing factors in regions where black is the dominant pigment. Different combinations of these strategies may account for the vast diversity of melanin patterns observed in insects. Copyright © 2016 by the Genetics Society of America.

  10. Melanin photosensitizes ultraviolet light (UVC) DNA damage in pigmented cells

    SciTech Connect

    Huselton, C.A.; Hill, H.Z. )

    1990-01-01

    Melanins, pigments of photoprotection and camouflage, are very photoreactive and can both absorb and emit active oxygen species. Nevertheless, black skinned individuals rarely develop skin cancer and melanin is assumed to act as a solar screen. Since DNA is the target for solar carcinogenesis, the effect of melanin on Ultraviolet (UV)-induced thymine lesions was examined in mouse melanoma and carcinoma cells that varied in melanin content. Cells prelabeled with 14C-dThd were irradiated with UVC; DNA was isolated, purified, degraded to bases by acid hydrolysis and analyzed by HPLC. Thymine dimers were detected in all of the extracts of irradiated cells. Melanotic and hypomelanotic but not mammary carcinoma cell DNA from irradiated cells contained hydrophilic thymine derivatives. The quantity of these damaged bases was a function of both the UVC dose and the cellular melanin content. One such derivative was identified by gas chromatography-mass spectroscopy as thymine glycol. The other appears to be derived from thymine glycol by further oxidation during acid hydrolysis of the DNA. The finding of oxidative DNA damage in melanin-containing cells suggests that melanin may be implicated in the etiology of caucasian skin cancer, particularly melanoma. Furthermore, the projected decrease in stratospheric ozone could impact in an unanticipated deleterious manner on dark-skinned individuals.

  11. Melanin photosensitizes ultraviolet light (UVC) DNA damage in pigmented cells.

    PubMed

    Huselton, C A; Hill, H Z

    1990-01-01

    Melanins, pigments of photoprotection and camouflage, are very photoreactive and can both absorb and emit active oxygen species. Nevertheless, black skinned individuals rarely develop skin cancer and melanin is assumed to act as a solar screen. Since DNA is the target for solar carcinogenesis, the effect of melanin on Ultraviolet (UV)-induced thymine lesions was examined in mouse melanoma and carcinoma cells that varied in melanin content. Cells prelabeled with 14C-dThd were irradiated with UVC; DNA was isolated, purified, degraded to bases by acid hydrolysis and analyzed by HPLC. Thymine dimers were detected in all of the extracts of irradiated cells. Melanotic and hypomelanotic but not mammary carcinoma cell DNA from irradiated cells contained hydrophilic thymine derivatives. The quantity of these damaged bases was a function of both the UVC dose and the cellular melanin content. One such derivative was identified by gas chromatography-mass spectroscopy as thymine glycol. The other appears to be derived from thymine glycol by further oxidation during acid hydrolysis of the DNA. The finding of oxidative DNA damage in melanin-containing cells suggests that melanin may be implicated in the etiology of caucasian skin cancer, particularly melanoma. Furthermore, the projected decrease in stratospheric ozone could impact in an unanticipated deleterious manner on dark-skinned individuals.

  12. Binding characteristics of fluoroquinolones to synthetic levodopa melanin.

    PubMed

    Ono, Chiho; Tanaka, Makoto

    2003-08-01

    To define the binding characteristics of fluoroquinolones to synthetic levodopa melanin, the binding of various drugs, including levofloxacin and ofloxacin, and positive controls (timolol and chloroquine), was investigated in-vitro. The affinity and capacity of the drug binding were calculated by Langmuir's adsorption isotherm. The affinity constant (K) and the binding capacity (r(max)) of levofloxacin were similar to those of timolol and much lower than those of chloroquine. Racemic ofloxacin and its enantiomers showed similar K and r(max), suggesting that the binding lacked stereoselectivity. The binding experiment with levofloxacin derivatives indicated that the basic nitrogen atom at position 7 of the quinolone ring, but not carboxyl group at position 3, would play a critical role in the interaction of fluoroquinolones with melanin. The melanin-drug complexes of levofloxacin and chloroquine were washed with neutral phosphate buffer, ethanol and 1 M HCl solution to explain the nature of the interaction of melanin with the drugs. Electrostatic forces mainly participate in the formation of the chloroquine-melanin complex, whereas van der Waals' and hydrophobic interactions are involved in the levofloxacin-melanin complex in addition to electrostatic forces. The interactions of various fluoroquinolones such as norfloxacin, enoxacin, sparfloxacin, ciprofloxacin and lomefloxacin with melanin were also studied. The results showed that the relative K value was: chloroquine approximately ciprofloxacin, sparfloxacin >/= lomefloxacin > timolol, levofloxacin approximately enoxacin, norfloxacin, and that the relative r(max) value was: norfloxacin, enoxacin >/= chloroquine, sparfloxacin > levofloxacin, ciprofloxacin, timolol, lomefloxacin. The fluoroquinolones vary in their affinity and capacity to bind with melanin, and ciprofloxacin and sparfloxacin showed a stronger interaction with melanin than the other fluoroquinolones studied.

  13. Fungal Melanin: What do We Know About Structure?

    PubMed Central

    Nosanchuk, Joshua D.; Stark, Ruth E.; Casadevall, Arturo

    2015-01-01

    The production of melanin significantly enhances the virulence of many important human pathogenic fungi. Despite fungal melanin’s importance in human disease, as well as melanin’s contribution to the ability of fungi to survive in diverse hostile environments, the structure of melanin remains unsolved. Nevertheless, ongoing research efforts have progressively revealed several notable structural characteristics of this enigmatic pigment, which will be the focus of this review. These compositional and organizational insights could further our ability to develop novel therapeutic approaches to combat fungal disease and enhance our understanding of how melanin is inserted into the cell wall. PMID:26733993

  14. Subcellular Compartmentalization and Trafficking of the Biosynthetic Machinery for Fungal Melanin.

    PubMed

    Upadhyay, Srijana; Xu, Xinping; Lowry, David; Jackson, Jennifer C; Roberson, Robert W; Lin, Xiaorong

    2016-03-22

    Protection by melanin depends on its subcellular location. Although most filamentous fungi synthesize melanin via a polyketide synthase pathway, where and how melanin biosynthesis occurs and how it is deposited as extracellular granules remain elusive. Using a forward genetic screen in the pathogen Aspergillus fumigatus, we find that mutations in an endosomal sorting nexin abolish melanin cell-wall deposition. We find that all enzymes involved in the early steps of melanin biosynthesis are recruited to endosomes through a non-conventional secretory pathway. In contrast, late melanin enzymes accumulate in the cell wall. Such subcellular compartmentalization of the melanin biosynthetic machinery occurs in both A. fumigatus and A. nidulans. Thus, fungal melanin biosynthesis appears to be initiated in endosomes with exocytosis leading to melanin extracellular deposition, much like the synthesis and trafficking of mammalian melanin in endosomally derived melanosomes.

  15. [Generation of superoxides during the interaction of melanins with oxygen].

    PubMed

    Lapina, V A; Dontsov, A E; Ostrovskiĭ, M A

    1984-10-01

    The rate of nitroblue tetrazolium (NBT) reduction by dihydroxyphenylalanine-melanin, pheomelanin and retinal pigment epithelium melanosomes under aerobic conditions (pH 7.4) is low both in the dark and upon illumination, but increases drastically in the presence of cetyltrimethylammonium bromide (CTAB). Under these conditions, the light insignificantly stimulates NBT reduction (1.3-fold). The reaction is effectively inhibited by superoxide dismutase. This suggests that superoxide anions (O2-. are formed as intermediate reaction products in the course of NBT reduction by melanins. At alkaline values of pH (greater than or equal to 9.0), the O2-.-dependent reduction of NBT can also take place in the absence of CTAB. In contrast with oxidation of photoreduced riboflavin, the melanin oxidation by O2 cannot induce lipid peroxidation. It is concluded that O2-. generation via melanin oxidation of melanosomes occurs only under non-physiological conditions and can hardly take place in vivo.

  16. Melanin content in melanoma metastases affects the outcome of radiotherapy.

    PubMed

    Brożyna, Anna A; Jóźwicki, Wojciech; Roszkowski, Krzysztof; Filipiak, Jan; Slominski, Andrzej T

    2016-04-05

    Melanin possess radioprotective and scavenging properties, and its presence can affect the behavior of melanoma cells, its surrounding environment and susceptibility to the therapy, as showed in vitro experiments. To determine whether melanin presence in melanoma affects the efficiency of radiotherapy (RTH) we evaluated the survival time after RTH treatment in metastatic melanoma patients (n = 57). In another cohort of melanoma patients (n = 84), the relationship between melanin level and pT and pN status was determined. A significantly longer survival time was found in patients with amelanotic metastatic melanomas in comparison to the melanotic ones, who were treated with either RTH or chemotherapy (CHTH) and RTH. These differences were more significant in a group of melanoma patients treated only with RTH. A detailed analysis of primary melanomas revealed that melanin levels were significantly higher in melanoma cells invading reticular dermis than the papillary dermis. A significant reduction of melanin pigmentation in pT3 and pT4 melanomas in comparison to pT1 and T2 tumors was observed. However, melanin levels measured in pT3-pT4 melanomas developing metastases (pN1-3, pM1) were higher than in pN0 and pM0 cases. The presence of melanin in metastatic melanoma cells decreases the outcome of radiotherapy, and melanin synthesis is related to higher disease advancement. Based on our previous cell-based and clinical research and present research we also suggest that inhibition of melanogenesis can improve radiotherapy modalities. The mechanism of relationship between melanogenesis and efficacy of RTH requires additional studies, including larger melanoma patients population and orthotopic, imageable mouse models of metastatic melanoma.

  17. Isolation of a novel strain of Aeromonas media producing high levels of DOPA-melanin and assessment of the photoprotective role of the melanin in bioinsecticide applications.

    PubMed

    Wan, X; Liu, H M; Liao, Y; Su, Y; Geng, J; Yang, M Y; Chen, X D; Shen, P

    2007-12-01

    To isolate a bacterium that produces high yield of melanin and to examine the effect of this bacterial pigment on the efficacy of a bioinsecticide. A novel melanin-producing bacterium, designated as strain WS, was isolated from the East Lake, Wuhan, China. Taxonomic studies of this strain indicate that it belongs to Aeromonas media. Physicochemical analysis of the pigment produced by strain WS (melanin WS) suggests that it is the authentic 3,4-dihydroxyphenylalanine (DOPA)-melanin. This melanin and that produced by Pseudomonas maltophilia P28 (melanin P28) share many biophysical properties, but the yield of the melanin WS is significantly higher than that of the melanin P28. In addition, the melanin WS appears to be more effective in the protection of a bioinsecticide against ultraviolet (UV) or solar radiation. At the concentration of 10 ppm, the melanin P28 exhibited no photoprotective effect on the bioinsecticide against UV radiation; in contrast, 5 ppm of melanin WS displayed an obvious protective effect. Similarly, the melanin WS displayed more protective effect on the bioinsecticide against solar radiation than the melanin P28 did over a 4-day period, with the effect being more dramatic for the last 2 days. We have isolated a novel bacterial strain of A. media that produces high levels of melanin. The melanin produced by this strain offers effective photoprotection of a commercial bioinsecticide BTI against UV and solar radiation. Our study suggests that the melanin produced by our newly isolated A. media strain has the potential to be used as a general photoprotective agent for bioinsecticides.

  18. Bird Integumentary Melanins: Biosynthesis, Forms, Function and Evolution.

    PubMed

    Galván, Ismael; Solano, Francisco

    2016-04-08

    Melanins are the ubiquitous pigments distributed in nature. They are one of the main pigments responsible for colors in living cells. Birds are among the most diverse animals regarding melanin-based coloration, especially in the plumage, although they also pigment bare parts of the integument. This review is devoted to the main characteristics of bird melanins, including updated views of the formation and nature of melanin granules, whose interest has been raised in the last years for inferring the color of extinct birds and non-avian theropod dinosaurs using resistant fossil feathers. The molecular structure of the two main types of melanin, eumelanin and pheomelanin, and the environmental and genetic factors that regulate avian melanogenesis are also presented, establishing the main relationship between them. Finally, the special functions of melanin in bird feathers are also discussed, emphasizing the aspects more closely related to these animals, such as honest signaling, and the factors that may drive the evolution of pheomelanin and pheomelanin-based color traits, an issue for which birds have been pioneer study models.

  19. Bird Integumentary Melanins: Biosynthesis, Forms, Function and Evolution

    PubMed Central

    Galván, Ismael; Solano, Francisco

    2016-01-01

    Melanins are the ubiquitous pigments distributed in nature. They are one of the main pigments responsible for colors in living cells. Birds are among the most diverse animals regarding melanin-based coloration, especially in the plumage, although they also pigment bare parts of the integument. This review is devoted to the main characteristics of bird melanins, including updated views of the formation and nature of melanin granules, whose interest has been raised in the last years for inferring the color of extinct birds and non-avian theropod dinosaurs using resistant fossil feathers. The molecular structure of the two main types of melanin, eumelanin and pheomelanin, and the environmental and genetic factors that regulate avian melanogenesis are also presented, establishing the main relationship between them. Finally, the special functions of melanin in bird feathers are also discussed, emphasizing the aspects more closely related to these animals, such as honest signaling, and the factors that may drive the evolution of pheomelanin and pheomelanin-based color traits, an issue for which birds have been pioneer study models. PMID:27070583

  20. [Intervention of nicotinamide on skin melanin genesis after UVA exposed].

    PubMed

    Patam, Muhammad; Jin, Xi-peng; Zhang, Yu-bin; Pan, Jian-ying; Shen, Guang-zu

    2007-08-01

    To investigate the interference effect of nicotinamide on UVA-induced melanin genesis and melanin transport in human skin melanocyte. The optimum UVA dose expected to cause cell proliferation: 0.2 J/cm(2), nicotinamide was added immediately after the 0.2 J/cm(2) UVA exposure and the melanin content, cell cycles, cell apoptosis and mRNA express level were measured respectively. Melanin content in melanocytes was increased significantly after exposed to 0.2 J/cm(2) UVA. Melanin content in melanocytes was decreased after treatment with 10.0 mmol/ml nicotinamide following UVA exposure, but the cell cycles and the cell apoptosis rate were not significantly altered. mRNA express levels of TYR, TRP-1 were modulated by nicotinamide. Nicotinamide has more effect on decreasing melanin genesis after UVA exposure, nicotinamide also plays a role in modulating the mRNA express of TYR, TRP-1 gene. It is possible to consider nicotinamide as an efficient and safe sun screen to provide a certain level of protection for UVA exposed skin.

  1. Melanins and their possible roles through biological evolution

    NASA Astrophysics Data System (ADS)

    Césarini, J. P.

    Melanins are biopolymers which structures can be very simple or very complex. From a single essential amino acid, phenylalanine, to fully mature melanosomes, a series of events takes place: melanogenesis. A part of haemoglobin, melanins are the only pigment endogenously synthesised in humans. Their synthesis takes place in the melanocyte, a cell from neurectodermal origin (neural crest, neural tube, melanoblasts). Two important functions have been attributed to melanin: optical efficiency of the eye and colour pattern, but their role might have been much larger in lower vertebrates and several micro-organisms. By their structure, melanins have very original biophysical bioproperties. They could act as intrinsic semiconductors and may de-excite certain biological molecules by converting electronic energy into heat. Being themselves free radicals, they certainly play a major role in the quenching of free radicals produced by ultraviolet radiation. In their granular or particular form, they absorb or reflect the non-ionising radiations. Furthermore, like weak cation exchange polymers, eumelanins have the capacity to bind substantial amount of metal ions or drugs. Phaeomelanins, sulphur containing low molecular weight, may have controlled the redox state of the early steps of life on earth. In human, the skin protection role attributed to melanins is controversial. If melanins have played a major role in the establishment of a North South gradient of skin colour, it is by no mean, an adaptation phenomenon for the darker population living under strong sun exposures.

  2. Synthetic melanin films: Assembling mechanisms, scaling behavior, and structural properties

    NASA Astrophysics Data System (ADS)

    Lorite, Gabriela S.; Coluci, Vitor R.; da Silva, Maria Ivonete N.; Dezidério, Shirlei N.; Graeff, Carlos Frederico O.; Galva~O, Douglas S.; Cotta, Mônica A.

    2006-06-01

    In this work we report on the surface characterization of melanin thin films prepared using both water-based and organic solvent-based melanin syntheses. Atomic force microscopy (AFM) analysis of these films suggests that the organic solvent synthesis provides relatively planar basic melanin structures; these basic structures generate surface steps with height in the range of 2-3 nm and small tendency to form larger aggregates. The scaling properties obtained from the AFM data were used to infer the assembling mechanisms of these thin films which depend on the solvent used for melanin synthesis. The behavior observed in organic solvent-based melanin suggests a diffusion-limited aggregation process. Thus films with good adhesion to the substrate and smoother morphologies than water-prepared melanin films are obtained. Electronic structure calculations using a conductorlike screening model were also performed in order to elucidate the microscopic processes of thin film formation. Our results suggest that the agglomerates observed in hydrated samples originate from reaction with water at specific locations on the surface most likely defects on the planar structure.

  3. Chemical characterization of melanins in sheep wool and human hair.

    PubMed

    Ozeki, H; Ito, S; Wakamatsu, K

    1996-04-01

    The color of hair and wool in mammals and feathers in birds is mostly determined by the quantity and quality of melanins that are synthesized in follicular melanocytes and transferred to keratinocytes. These are two chemically distinct types of melanin pigments: the black to brown eumelanins and the yellow to reddish pheomelanins. Melanins in sheep wool and human hair of various colors were characterized by HPLC methods to estimate 5,6-dihydroxyindole-2-carboxylic acid (DHICA)-derived units in eumelanins and benzothiazine units in pheomelanins. Melanins were also characterized by spectrophotometric methods after differential solubilization in alkalies. It was demonstrated that 1) black wool in Asiatic sheep contains eumelanin with the DHICA content similar to black mouse melanin, while black to brown melanins from human hair contain much lower ratios of DHICA-derived units, comparable to the slaty mutation in mice, 2) dark brown to brown hair in human contains eumelanin whose chemical properties are indistinguishable from those of black hair; 3) dark red wool and red human hair contain pheomelanic pigments whose chemical properties are rather different from those of yellow pheomelanins in mice, and 4) light brown, blonde, and red hairs in human can be differentiated from each other with this methodology.

  4. UVA phototransduction drives early melanin synthesis in human melanocytes.

    PubMed

    Wicks, Nadine L; Chan, Jason W; Najera, Julia A; Ciriello, Jonathan M; Oancea, Elena

    2011-11-22

    Exposure of human skin to solar ultraviolet radiation (UVR), a powerful carcinogen [1] comprising ~95% ultraviolet A (UVA) and ~5% ultraviolet B (UVB) at the Earth's surface, promotes melanin synthesis in epidermal melanocytes [2, 3], which protects skin from DNA damage [4, 5]. UVB causes DNA lesions [6] that lead to transcriptional activation of melanin-producing enzymes, resulting in delayed skin pigmentation within days [7]. In contrast, UVA causes primarily oxidative damage [8] and leads to immediate pigment darkening (IPD) within minutes, via an unknown mechanism [9, 10]. No receptor protein directly mediating phototransduction in skin has been identified. Here we demonstrate that exposure of primary human epidermal melanocytes (HEMs) to UVA causes calcium mobilization and early melanin synthesis. Calcium responses were abolished by treatment with G protein or phospholipase C (PLC) inhibitors or by depletion of intracellular calcium stores. We show that the visual photopigment rhodopsin [11] is expressed in HEMs and contributes to UVR phototransduction. Upon UVR exposure, significant melanin production was measured within one hour; cellular melanin continued to increase in a retinal- and calcium-dependent manner up to 5-fold after 24 hr. Our findings identify a novel UVA-sensitive signaling pathway in melanocytes that leads to calcium mobilization and melanin synthesis and may underlie the mechanism of IPD in human skin.

  5. 1,8-Dihydroxynaphthalene (DHN)-Melanin Biosynthesis Inhibitors Increase Erythritol Production in Torula corallina, and DHN-Melanin Inhibits Erythrose Reductase

    PubMed Central

    Lee, Jung-Kul; Jung, Hyung-Moo; Kim, Sang-Yong

    2003-01-01

    The yeast Torula corallina is a strong erythritol producer that is used in the industrial production of erythritol. However, melanin accumulation during culture represents a serious problem for the purification of erythritol from the fermentation broth. Melanin biosynthesis inhibitors such as 3,4-dihydroxyphenylalanine and 1,8-dihydroxynaphthalene (DHN)-melanin inhibitors were added to the T. corallina cultures. Only the DHN-melanin inhibitors showed an effect on melanin production, which suggests that the melanin formed during the culturing of T. corallina is derived from DHN. This finding was confirmed by the detection of a shunt product of the pentaketide pathway, flaviolin, and elemental analysis. Among the DHN-melanin inhibitors, tricyclazole was the most effective. Supplementation with tricyclazole enhanced the production of erythritol while significantly inhibiting the production of DHN-melanin and DHN-melanin biosynthetic enzymes, such as trihydroxynaphthalene reductase. The erythrose reductase from T. corallina was purified to homogeneity by ion-exchange and affinity chromatography. Purified erythrose reductase was significantly inhibited in vitro in a noncompetitive manner by elevated levels of DHN-melanin. In contrast, the level of erythrose reductase activity was unaffected by increasing concentrations of tricyclazole. These results suggest that supplemental tricyclazole reduces the production of DHN-melanin, which may lead to a reduction in the inhibition of erythrose reductase and a higher yield of erythritol. This is the first report to demonstrate that melanin biosynthesis inhibitors increase the production of a sugar alcohol in T. corallina. PMID:12788746

  6. The stepwise multi-photon activation fluorescence guided ablation of melanin

    NASA Astrophysics Data System (ADS)

    Lai, Zhenhua; Gu, Zetong; DiMarzio, Charles

    2015-02-01

    Previous research has shown that the stepwise multi-photon activation fluorescence (SMPAF) of melanin, activated and excited by a continuous-wave (CW) mode near infrared (NIR) laser, is a low-cost and reliable method for detecting melanin. We have developed a device utilizing the melanin SMPAF to guide the ablation of melanin with a 975 nm CW laser. This method provides the ability of targeting individual melanin particles with micrometer resolution, and enables localized melanin ablation to be performed without collateral damage. Compared to the traditional selective photothermolysis, which uses pulsed lasers for melanin ablation, this method demonstrates higher precision and lower cost. Therefore, the SMPAF guided selective ablation of melanin is a promising tool of melanin ablation for both medical and cosmetic purposes.

  7. Optical properties of cells with melanin

    NASA Astrophysics Data System (ADS)

    Rohde, Barukh; Coats, Israel; Krueger, James; Gareau, Dan

    2014-02-01

    The optical properties of pigmented lesions have been studied using diffuse reflectance spectroscopy in a noninvasive configuration on optically thick samples such as skin in vivo. However, it is difficult to un-mix the effects of absorption and scattering with diffuse reflectance spectroscopy techniques due to the complex anatomical distributions of absorbing and scattering biomolecules. We present a device and technique that enables absorption and scattering measurements of tissue volumes much smaller than the optical mean-free path. Because these measurements are taken on fresh-frozen sections, they are direct measurements of the optical properties of tissue, albeit in a different hydration state than in vivo tissue. Our results on lesions from 20 patients including melanomas and nevi show the absorption spectrum of melanin in melanocytes and basal keratinocytes. Our samples consisted of fresh frozen sections that were unstained. Fitting the spectrum as an exponential decay between 500 and 1100 nm [mua = A*exp(-B*(lambda-C)) + D], we report on the fit parameters of and their variation due to biological heterogeneity as A = 4.20e4 +/- 1.57e5 [1/cm], B = 4.57e-3 +/- 1.62e-3 [1/nm], C = 210 +/- 510 [nm] , D = 613 +/- 534 [1/cm]. The variability in these results is likely due to highly heterogeneous distributions of eumelanin and pheomelanin.

  8. Field melanin mapping of the hairless scalp.

    PubMed

    Piérard, Gérald E; Piérard-Franchimont, Claudine; Quatresooz, Pascale

    2012-11-01

    Mottled subclinical melanoderma (MSM) is frequently seen on facial skin using the ultraviolet light enhanced visualization (ULEV) method. The corresponding aspect on the hairless scalp remains unknown. To explore the field distribution of melanin on the scalp of fair-skinned Caucasian subjects. The scalp was examined in 43 men with androgenic alopecia. The Visioscan(®) camera provided the ULEV pictures. Another optical (Visioface(®) Quick) device was used under white light illumination followed by colour contrast enhancement. This was reached after specific computer filtration of the cyan hue wavelengths. Under white light illumination, the scalp looked normal. MSM patterns were disclosed by both optical procedures as evenly scattered discrete patchy fields of hypermelanosis. The smaller rounded spots were restricted to the lips of the hair infundibula. Larger irregularly shaped spots predominated in the interfollicular areas. A few hypomelanotic spots were scattered over the scalp. The present observations based on dual optical methods possibly provide information about a patterned pathobiology of melanocytes on the scalp. The spotty MSM pattern looked similar to the reported aspects on the face. It somewhat resembled the widespread PUVA-induced lentiginosis. © 2011 John Wiley & Sons A/S.

  9. Biosynthesis and Functions of Melanin in Sporothrix schenckii

    PubMed Central

    Romero-Martinez, Rafael; Wheeler, Michael; Guerrero-Plata, Antonieta; Rico, Guadalupe; Torres-Guerrero, Haydée

    2000-01-01

    Sporothrix schenckii is a human pathogen that causes sporotrichosis, an important cutaneous mycosis with a worldwide distribution. It produces dark-brown conidia, which infect the host. We found that S. schenckii synthesizes melanin via the 1,8-dihydroxynaphthalene pentaketide pathway. Melanin biosynthesis in the wild type was inhibited by tricyclazole, and colonies of the fungus were reddish brown instead of black on tricyclazole-amended medium. Two melanin-deficient mutant strains were analyzed in this study: an albino that produced normal-appearing melanin on scytalone-amended medium and a reddish brown mutant that accumulated and extruded melanin metabolites into its medium. Scytalone and flaviolin obtained from cultures of the reddish brown mutant were identified by thin-layer chromatography, high-performance liquid chromatography, and UV spectra. Transmission electron microscopy showed an electron-dense granular material believed to be melanin in wild-type conidial cell walls, and this was absent in conidial walls of the albino mutant unless the albino was grown on a scytalone-amended medium. Melanized cells of wild-type S. schenckii and the albino grown on scytalone-amended medium were less susceptible to killing by chemically generated oxygen- and nitrogen-derived radicals and by UV light than were conidia of the mutant strains. Melanized conidia of the wild type and the scytalone-treated albino were also more resistant to phagocytosis and killing by human monocytes and murine macrophages than were unmelanized conidia of the two mutants. These results demonstrate that melanin protects S. schenckii against certain oxidative antimicrobial compounds and against attack by macrophages. PMID:10816530

  10. Chemosorption of radiometals of interest to nuclear medicine by synthetic melanins.

    PubMed

    Howell, Robertha C; Schweitzer, Andrew D; Casadevall, Arturo; Dadachova, Ekaterina A

    2008-04-01

    Melanins are high-molecular-weight pigments that are ubiquitous in nature and can also be synthesized in the laboratory from a variety of precursors. Melanins possess numerous interesting physicochemical characteristics, including electromagnetic radiation absorption properties and ability to chelate metals. We have recently reported that melanin has remarkable ionizing-radiation-shielding properties, possibly because it can interact with photons via Compton scattering. We hypothesized that, if administered internally, melanin could play a beneficial role by scavenging various radionuclides, in addition to radiation shielding. Three melanins were synthesized from dopamine, 3,4-dihydroxyphenylalanine (l-Dopa) and a combination of l-cysteine and l-Dopa. For control, synthetic melanin made from tyrosine polymerization (Sigma) was used. Melanins were characterized by elemental analysis. The chemosorption of 111In, 225Ac and 213Bi by melanins was studied at 37 degrees C for up to 48 h. The C-to-N molar ratios for dopamine, l-Dopa and tyrosine melanins were very close at 7.92, 8.39 and 8.48, respectively, while in mixed l-cysteine/l-Dopa melanin, that ratio was much lower at 3.63. This mixed melanin also contained 22.33% sulfur, thus confirming incorporation of S-containing motifs into its structure. Dopamine, l-Dopa and tyrosine melanins were very similar in their abilities to decrease the activity of 111In, 225Ac and 213Bi and their radioactive daughters in supernatants by >10-fold in comparison with the starting levels, while mixed l-cysteine/l-Dopa melanin was able to chemosorb only 111In. We have demonstrated that synthetic melanins made of diverse precursors can chemosorb 111In, 213Bi and 225Ac, with dopamine, l-Dopa and tyrosine melanins being the most efficient towards all three of these radionuclides. Such properties of synthetic melanins can contribute to the development of the novel melanin-based radioprotective materials.

  11. Paramagnetic Centers in DOPA-Melanin-Dihydrostreptomycin Complexes

    NASA Astrophysics Data System (ADS)

    Buszman, E.; Pilawa, B.; Zdybel, M.; Wrześniok, D.; Grzegorczyk, A.; Wilczok, T.

    2006-08-01

    DOPA-melanin-dihydrostreptomycin complexes with drug concentrations 1×10-4-1×10-2 M were examined by the use of electron paramagnetic resonance spectroscopy at X-band (9.3 GHz). Dihydrostreptomycin was chosen for studies, because this aminoglycoside antibiotic causes strong toxic effects in organism. It was stated that dihydrostreptomycin generates o-semiquinone free radicals with g=2.0038 in melanin. Free radicals formation increases with increase in the antibiotic concentration. Changes of EPR lines with microwave powers pointed out that slow spin-lattice relaxation processes exist in DOPA-melanin and in its complexes with dihydrostreptomycin. The measured EPR lines were homogeneously broadened.

  12. Suppression of Melanin Production by Expression of HSP70*

    PubMed Central

    Hoshino, Tatsuya; Matsuda, Minoru; Yamashita, Yasuhiro; Takehara, Masaya; Fukuya, Masayo; Mineda, Kazutaka; Maji, Daisuke; Ihn, Hironobu; Adachi, Hiroaki; Sobue, Gen; Funasaka, Yoko; Mizushima, Tohru

    2010-01-01

    Skin hyperpigmentation disorders due to abnormal melanin production induced by ultraviolet (UV) irradiation are both a clinical and cosmetic problem. UV irradiation stimulates melanin production in melanocytes by increasing intracellular cAMP. Expression of heat shock proteins (HSPs), especially HSP70, is induced by various stressors, including UV irradiation, to provide cellular resistance to such stressors. In this study we examined the effect of expression of HSP70 on melanin production both in vitro and in vivo. 3-Isobutyl-1-methylxanthine (IBMX), a cAMP-elevating agent, stimulated melanin production in cultured mouse melanoma cells, and this stimulation was suppressed in cells overexpressing HSP70. IBMX-dependent transcriptional activation of the tyrosinase gene was also suppressed in HSP70-overexpressing cells. Expression of microphthalmia-associated transcription factor (MITF), which positively regulates transcription of the tyrosinase gene, was up-regulated by IBMX; however, this up-regulation was not suppressed in HSP70-overexpressing cells. On the other hand, immunoprecipitation and immunostaining analyses revealed a physical interaction between and co-localization of MITF and HSP70, respectively. Furthermore, the transcription of tyrosinase gene in nuclear extract was inhibited by HSP70. In vivo, UV irradiation of wild-type mice increased the amount of melanin in the basal layer of the epidermis, and this increase was suppressed in transgenic mice expressing HSP70. This study provides the first evidence of an inhibitory effect of HSP70 on melanin production both in vitro and in vivo. This effect seems to be mediated by modulation of MITF activity through a direct interaction between HSP70 and MITF. PMID:20177067

  13. Melanin determination by high performance liquid chromatography (HPLC) for K. marxianus

    USDA-ARS?s Scientific Manuscript database

    Ultraviolet light (UV) mutated K. marxianus was found to turn dark brown during a growth assay. This brown color was hypothesized to be melanin overproduction influenced by the UV exposure. Cell cultures were oxidized and HPLC analyzed to determine melanin concentrations. The resulting melanin con...

  14. Differential Antifungal Activity of Human and Cryptococcal Melanins with Structural Discrepancies

    PubMed Central

    Correa, Néstor; Covarrubias, Cristian; Rodas, Paula I.; Hermosilla, Germán; Olate, Verónica R.; Valdés, Cristián; Meyer, Wieland; Magne, Fabien; Tapia, Cecilia V.

    2017-01-01

    Melanin is a pigment found in all biological kingdoms, and plays a key role in protection against ultraviolet radiation, oxidizing agents, and ionizing radiation damage. Melanin exerts an antimicrobial activity against bacteria, fungi, and parasites. We demonstrated an antifungal activity of synthetic and human melanin against Candida sp. The members of the Cryptococcus neoformans and C. gattii species complexes are capsulated yeasts, which cause cryptococcosis. For both species melanin is an important virulence factor. To evaluate if cryptococcal and human melanins have antifungal activity against Cryptococcus species they both were assayed for their antifungal properties and physico-chemical characters. Melanin extracts from human hair and different strains of C. neoformans (n = 4) and C. gattii (n = 4) were investigated. The following minimum inhibitory concentrations were found for different melanins against C. neoformans and C. gattii were (average/range): 13.7/(7.8–15.6) and 19.5/(15.6–31.2) μg/mL, respectively, for human melanin; 273.4/(125–>500) and 367.2/(125.5–>500) μg/mL for C. neoformans melanin and 125/(62.5–250) and 156.2/(62–250) μg/mL for C. gattii melanin. Using Scanning Electron Microscopy we observed that human melanin showed a compact conformation and cryptococcal melanins exposed an amorphous conformation. Infrared spectroscopy (FTIR) showed some differences in the signals related to C-C bonds of the aromatic ring of the melanin monomers. High Performance Liquid Chromatography established differences in the chromatograms of fungal melanins extracts in comparison with human and synthetic melanin, particularly in the retention time of the main compound of fungal melanin extracts and also in the presence of minor unknown compounds. On the other hand, MALDI-TOF-MS analysis showed slight differences in the spectra, specifically the presence of a minor intensity ion in synthetic and human melanin, as well as in some fungal melanin

  15. Differential Antifungal Activity of Human and Cryptococcal Melanins with Structural Discrepancies.

    PubMed

    Correa, Néstor; Covarrubias, Cristian; Rodas, Paula I; Hermosilla, Germán; Olate, Verónica R; Valdés, Cristián; Meyer, Wieland; Magne, Fabien; Tapia, Cecilia V

    2017-01-01

    Melanin is a pigment found in all biological kingdoms, and plays a key role in protection against ultraviolet radiation, oxidizing agents, and ionizing radiation damage. Melanin exerts an antimicrobial activity against bacteria, fungi, and parasites. We demonstrated an antifungal activity of synthetic and human melanin against Candida sp. The members of the Cryptococcus neoformans and C. gattii species complexes are capsulated yeasts, which cause cryptococcosis. For both species melanin is an important virulence factor. To evaluate if cryptococcal and human melanins have antifungal activity against Cryptococcus species they both were assayed for their antifungal properties and physico-chemical characters. Melanin extracts from human hair and different strains of C. neoformans (n = 4) and C. gattii (n = 4) were investigated. The following minimum inhibitory concentrations were found for different melanins against C. neoformans and C. gattii were (average/range): 13.7/(7.8-15.6) and 19.5/(15.6-31.2) μg/mL, respectively, for human melanin; 273.4/(125->500) and 367.2/(125.5->500) μg/mL for C. neoformans melanin and 125/(62.5-250) and 156.2/(62-250) μg/mL for C. gattii melanin. Using Scanning Electron Microscopy we observed that human melanin showed a compact conformation and cryptococcal melanins exposed an amorphous conformation. Infrared spectroscopy (FTIR) showed some differences in the signals related to C-C bonds of the aromatic ring of the melanin monomers. High Performance Liquid Chromatography established differences in the chromatograms of fungal melanins extracts in comparison with human and synthetic melanin, particularly in the retention time of the main compound of fungal melanin extracts and also in the presence of minor unknown compounds. On the other hand, MALDI-TOF-MS analysis showed slight differences in the spectra, specifically the presence of a minor intensity ion in synthetic and human melanin, as well as in some fungal melanin extracts. We

  16. Effects of polyphenol compounds melanin on NAFLD/NASH prevention.

    PubMed

    Belemets, Natalia; Kobyliak, Nazarii; Virchenko, Oleksandr; Falalyeyeva, Tetyana; Olena, Tsyryuk; Bodnar, Petro; Savchuk, Oleksiy; Galenova, Tetyana; Caprnda, Martin; Rodrigo, Luis; Skladany, Lubomir; Delev, Delian; Opatrilova, Radka; Kruzliak, Peter; Beregova, Tetyana; Ostapchenko, Lyudmyla

    2017-04-01

    One of the pathogenic mechanisms of the progression non-alcoholic liver disease (NAFLD) to nonalcoholic steatohepatitis (NASH) is the accumulation of reactive oxygen species (ROS). So, antioxidant therapy is necessary for successful treatment of the liver injury. We have paid attention to melanin produced by yeast Nadsoniella nigra strain X-1 as novel antioxidant and anti-inflammatory agents with low toxicity. In current study we aimed to investigate the preventive effect of melanin on the monosodium glutamate (MSG) induced NAFLD model in rats. The study was carried out on 45 Wistar rats that were divided into 3 groups: intact, MSG- and MSG+melanin groups (n=15 in each group). Newborn rats of MSG- and MSG+melanin groups were administered with MSG (4mg/g, 8μl/g, subcutaneously) at 2nd-10th days of life. Since the age of 1 month, rats of MSG-group were treated with water (0.25ml/100g), rats of MSG+melanin groups-with melanin (1mg/kg) dissolved in water (0.25ml/100g). had been performed intermittently (two-week courses alternated with two-week breaks) for 3 months. In 4-month rats anthropometrical parameters and visceral adipose tissue (VAT) mass were estimated. To assess morphological changes in liver we used NAS (NAFLD activity score). The content of pro-inflammatory cytokines (interleukin (IL)-1β, IL-12Bp40, interferon (INF)-γ) and anti-inflammatory cytokines (IL-4, IL-10, tumor growth factor (TGF)-β) were measured by ELISA. We found significantly lower total score (1.0±0.19 vs 3.33±0.36, p<0.001), degree of steatosis (0.73±0.18 vs 1.80±0.17, p<0.001) and manifestation of lobular inflammation (0.27±0.11 vs 1.20±0.17, p<0.001) due to NAFLD activity score in MSG+melanin group compared to MSG-obesity. NASH we confirmed only in 33.3% of rats with MSG-obesity that was significantly higher than after melanin (6.7%) administration (p=0.033). Melanin administration reduce amount of visceral fat on 44.5% (p<0.001) as compared to MSG-obesity group. Melanin reduced

  17. Melanin and the ecology of southern pine beetle associated fungi

    Treesearch

    Kier D. Klepzig

    2006-01-01

    I report here a series of initial investigations into effects of melanins on the interactions of the three primary species of fungi associated with the southern pine beetle (SPB), and into possible means for mitigating the damaging activities of the melanistic fungus, Ophiostoma minus. Growth of the SPB mutualistic fungus Entomocorticium...

  18. [Synthesis of melanin pigments by Antarctic black yeast].

    PubMed

    Tashirev, A B; Romanovskaia, V A; Rokitko, P V; Matveeva, N A; Shilin, S O; Tashireva, A A

    2012-01-01

    Five strains of the black yeast similar to Exophiala nigra (Nadsoniela nigra), which we have isolated from the Antarctic biotopes, are studied. At cultivation in a periodic operation the maximum level of absolutely dry biomass in five tested strains constituted 3.2-7.8 g/l of medium, melanin pigment yield being 6-9% of absolutely dry mass of cells. Two highly productive strains have been selected. Pigments of the studied black yeast are water-insoluble, however dissolve in alkali and concentrated acids. The maximum absorption of the yeast pigments was in the range of 220 nm. The above-stated properties of pigments of the investigated yeast correspond to the description of melanin fractions of Nadsoniela nigra and some microscopic mushrooms. The water-soluble melanin-pigments have been obtained after the dialysis of alkaline solution of the pigment. UV-spectra and visible absorption spectra of water solution of melanin-pigments are almost identical to those of initial alkaline solutions. It is shown that the studied yeast are resistant to high concentrations of toxic metals (Hg2+, Cu2+, Co2+, Cr(VI) and Ni2+), and introduction of Co2+ into the cultivation medium leads to the increase of pigments synthesis.

  19. The actions of melanin and melanocyte stimulating hormone (MSH).

    PubMed

    Rasmussen, Natalie; Nelson, Francine; Govitrapong, Piyarat; Ebadi, Manuchair

    1999-01-01

    The skin, the largest organ of the body, plays an important role in the total metabolism of several hormones. Melanin, the major product of the melanocyte, is largely responsible for the coloring of skin. Melanin is a complex of insoluble, polyquinone, brown or red pigment and protein, formed by the oxidation of tyrosine and 3,4-dihydroxyphenylalanine in the presence of tyrosinase. There exists two main groups of melanin: the black to dark-brown insoluble eumelanins and the yellow to reddish brown, alkali-soluble pheomelanins. MSH, ACTH and beta-lipoprotein are able to influence skin pigmentation. The functions attributed to melanins are acting as a barrier against ionizing radiation; participating in developmental processes, serving as a cosmetic entity, and scavenging cytotoxic radicals and intermediates. Melanocytes express numerous receptors that allow interaction with other cells in their microenvironment, including keratinocytes and the immune component of the skin Langerhans cells. Albinism represents a group of inherited abnormalities that present with congenital hypopigmentation that can involve the skin, hair, and eyes (oculocutaneous albinism) or be limited primarily to the eyes (ocular albinism). The inherited disorders of keratin include epidermolysis bullosu simplex causing cell degeneration within the basal layer. Sunlight and ultraviolet radiation from artificial light sources could be tonic or toxic to human skin. The harmful effects of solar radiation are skin cancer, photosensitivity diseases, sunburn, photoallergy, photoimmunologic alterations, cataracts, mutations, skin aging and phototoxicity. Sunscreen chemicals protect the skin against ultraviolet radiation.

  20. Melanin: the biophysiology of oral melanocytes and physiological oral pigmentation

    PubMed Central

    2014-01-01

    The presence of melanocytes in the oral epithelium is a well-established fact, but their physiological functions are not well defined. Melanin provides protection from environmental stressors such as ultraviolet radiation and reactive oxygen species; and melanocytes function as stress-sensors having the capacity both to react to and to produce a variety of microenvironmental cytokines and growth factors, modulating immune, inflammatory and antibacterial responses. Melanocytes also act as neuroendocrine cells producing local neurotransmitters including acetylcholine, catecholamines and opioids, and hormones of the melanocortin system such as proopiomelanocortin, adrenocorticotropic hormone and α-melanocyte stimulating hormone, that participate in intracellular and in intercellular signalling pathways, thus contributing to tissue homeostasis. There is a wide range of normal variation in melanin pigmentation of the oral mucosa. In general, darker skinned persons more frequently have oral melanin pigmentation than light-skinned persons. Variations in oral physiological pigmentation are genetically determined unless associated with some underlying disease. In this article, we discuss some aspects of the biophysiology of oral melanocytes, of the functions of melanin, and of physiological oral pigmentation. PMID:24661309

  1. Melanin: the biophysiology of oral melanocytes and physiological oral pigmentation.

    PubMed

    Feller, Liviu; Masilana, Aubrey; Khammissa, Razia A G; Altini, Mario; Jadwat, Yusuf; Lemmer, Johan

    2014-03-24

    The presence of melanocytes in the oral epithelium is a well-established fact, but their physiological functions are not well defined. Melanin provides protection from environmental stressors such as ultraviolet radiation and reactive oxygen species; and melanocytes function as stress-sensors having the capacity both to react to and to produce a variety of microenvironmental cytokines and growth factors, modulating immune, inflammatory and antibacterial responses. Melanocytes also act as neuroendocrine cells producing local neurotransmitters including acetylcholine, catecholamines and opioids, and hormones of the melanocortin system such as proopiomelanocortin, adrenocorticotropic hormone and α-melanocyte stimulating hormone, that participate in intracellular and in intercellular signalling pathways, thus contributing to tissue homeostasis.There is a wide range of normal variation in melanin pigmentation of the oral mucosa. In general, darker skinned persons more frequently have oral melanin pigmentation than light-skinned persons. Variations in oral physiological pigmentation are genetically determined unless associated with some underlying disease.In this article, we discuss some aspects of the biophysiology of oral melanocytes, of the functions of melanin, and of physiological oral pigmentation.

  2. Melanin as a virulence factor of Paracoccidioides brasiliensis and other dimorphic pathogenic fungi

    PubMed Central

    Taborda, Carlos P.; da Silva, Marcelo B.; Nosanchuk, Joshua D.; Travassos, Luiz R.

    2008-01-01

    Melanin pigments are substances produced by a broad variety of pathogenic microorganisms, including bacteria, fungi, and helminths. Microbes predominantly produce melanin pigment via tyrosinases, laccases, catecholases, and the polyketide synthase pathway. In fungi, melanin is deposited in the cell wall and cytoplasm, and melanin particles (“ghosts”) can be isolated from these fungi that have the same size and shape of the original cells. Melanin has been reported in several human pathogenic dimorphic fungi including Paracoccidioides brasiliensis, Sporothrix schenckii, Histoplasma capsulatum, Blastomyces dermatitidis, and Coccidioides posadasii. Melanization appears to contribute to virulence by reducing the susceptibility of melanized fungi to host defense mechanisms and antifungal drugs. PMID:18777637

  3. Structural Characterization of Melanin Pigments from Commercial Preparations of the Edible Mushroom Auricularia auricula.

    PubMed

    Prados-Rosales, Rafael; Toriola, Stacy; Nakouzi, Antonio; Chatterjee, Subhasish; Stark, Ruth; Gerfen, Gary; Tumpowsky, Paul; Dadachova, Ekaterina; Casadevall, Arturo

    2015-08-26

    Many of the most widely consumed edible mushrooms are pigmented, and these have been associated with some beneficial health effects. Nevertheless, the majority of the reported compounds associated with these desirable properties are non-pigmented. We have previously reported that melanin pigment from the edible mushroom Auricularia auricula can protect mice against ionizing radiation, although no physicochemical characterization was reported. Consequently, in this study we have characterized commercial A. auricula mushroom preparations for melanin content and carried out structural characterization of isolated insoluble melanin materials using a panel of sophisticated spectroscopic and physical/imaging techniques. Our results show that approximately 10% of the dry mass of A. auricula is melanin and that the pigment has physicochemical properties consistent with those of eumelanins, including hosting a stable free radical population. Electron microscopy studies show that melanin is associated with the mushroom cell wall in a manner similar to that of melanin from the model fungus C. neoformans. Elemental analysis of melanin indicated C, H, and N ratios consistent with 5,6-dihydroxyindole-2-carboxylic acid/5,6-dihydroxyindole and 1,8-dihydroxynaphthalene eumelanin. Validation of the identity of the isolated product as melanin was achieved by EPR analysis. A. auricula melanin manifested structural differences, relative to the C. neoformans melanin, with regard to the variable proportions of alkyl chains or oxygenated carbons. Given the necessity for new oral and inexpensive radioprotective materials coupled with the commercial availability of A. auricula mushrooms, this product may represent an excellent source of edible melanin.

  4. Synthesis of melanin-like pigments by Sporothrix schenckii in vitro and during mammalian infection.

    PubMed

    Morris-Jones, Rachael; Youngchim, Sirida; Gomez, Beatriz L; Aisen, Phil; Hay, Roderick J; Nosanchuk, Joshua D; Casadevall, Arturo; Hamilton, Andrew J

    2003-07-01

    Melanin has been implicated in the pathogenesis of several important human fungal pathogens. Existing data suggest that the conidia of the dimorphic fungal pathogen Sporothrix schenckii produce melanin or melanin-like compounds; in this study we aimed to confirm this suggestion and to demonstrate in vitro and in vivo production of melanin by yeast cells. S. schenckii grown on Mycosel agar produced visibly pigmented conidia, although yeast cells grown in brain heart infusion and minimal medium broth appeared to be nonpigmented macroscopically. However, treatment of both conidia and yeast cells with proteolytic enzymes, denaturant, and concentrated hot acid yielded dark particles similar in shape and size to the corresponding propagules, which were stable free radicals consistent with identification as melanins. Melanin particles extracted from S. schenckii yeast cells were used to produce a panel of murine monoclonal antibodies (MAbs) which labeled pigmented conidia, yeast cells, and the isolated particles. Tissue from hamster testicles infected with S. schenckii contained fungal cells that were labeled by melanin-binding MAbs, and digestion of infected hamster tissue yielded dark particles that were also reactive. Additionally, sera from humans with sporotrichosis contained antibodies that bound melanin particles. These findings indicate that S. schenckii conidia and yeast cells can produce melanin or melanin-like compounds in vitro and that yeast cells can synthesize pigment in vivo. Since melanin is an important virulence factor in other pathogenic fungi, this pigment may have a similar role in the pathogenesis of sporotrichosis.

  5. Dispersive Raman spectroscopy allows the identification and quantification of melanin types

    PubMed Central

    Galván, Ismael; Jorge, Alberto

    2015-01-01

    Melanins are the most prevalent pigments in animals and are involved in visual communication by producing colored traits that often evolve as intraspecific signals of quality. Identifying and quantifying melanins are therefore essential to understand the function and evolution of melanin-based signals. However, the analysis of melanins is difficult due to their insolubility and the lack of simple methods that allow the identification of their chemical forms. We recently proposed the use of Raman spectroscopy as a simple, noninvasive technique that can be used to identify and quantify melanins in feathers and hairs. Contrarily, other authors later stated that melanins are characterized by a lack of defined Raman signals. Here, we use confocal Raman microscopy to confirm previous analyses showing that the two main chemical forms of melanins (eumelanin and pheomelanin) exhibit distinct Raman signal and compare different excitation wavelengths to analyze synthetic pheomelanin and natural melanins in feathers of different species of birds. Our analyses indicate that only laser excitation wavelengths below 1064 nm are useful for the analysis of melanins by Raman spectroscopy, and only 780-nm laser in the case of melanins in feathers. These findings show that the capacity of Raman spectroscopy to distinguish different chemical forms of melanins depends on laser power and integration time. As a consequence, Raman spectroscopy should be applied after preliminar analyses using a range of these parameters, especially in fragile biological tissues such as feathers. PMID:25897382

  6. Isolation, purification and physicochemical characterization of water-soluble Bacillus thuringiensis melanin.

    PubMed

    Aghajanyan, Armen E; Hambardzumyan, Artur A; Hovsepyan, Anichka S; Asaturian, Rafael A; Vardanyan, Andranik A; Saghiyan, Ashot A

    2005-04-01

    Melanins are widely used in medicine, pharmacology, cosmetics and other fields. Although several technologies for the purification of water-insoluble dioxyphenylalanine (DOPA) melanins have been described, a source of water-soluble melanin is highly desirable. Here we describe an effective procedure for the isolation and purification of water-soluble melanin using the culture medium of Bacillus thuringiensis subsp. galleriae strain K1. Water-soluble melanin from this organism has an isoelectric point (pI=3.0-3.2) and was purified optimally by adsorbtion using the IA-1r resin and elution as a concentrated solution. The purified melanin obtained exhibited a similar infra-red absorbtion spectrum to synthetic melanin and contained quinolic and phenolic structures and an amino acid content of around 20% after acid hydrolysis. The molecular weight of the purified melanin determined by SDS-PAGE was 4 kDa and the electromagnetic spin resonance spectrum of the purified microbial melanin was a slightly asymmetric singlet without hyperfine structure with about 7 Gauss width of the line between points of the maximum incline and g=2.006. The concentration of paramagnetic centers in melanin is 0.21x10(18) spin/g. The results obtained provide a rapid, simple and inexpensive method for the large scale purification of water soluble melanin that may have widespread applications.

  7. Paraquat-Melanin Redox-Cycling: Evidence from Electrochemical Reverse Engineering.

    PubMed

    Kim, Eunkyoung; Leverage, W Taylor; Liu, Yi; Panzella, Lucia; Alfieri, Maria Laura; Napolitano, Alessandra; Bentley, William E; Payne, Gregory F

    2016-08-17

    Parkinson's disease is a neurodegenerative disorder associated with oxidative stress and the death of melanin-containing neurons of the substantia nigra. Epidemiological evidence links exposure to the pesticide paraquat (PQ) to Parkinson's disease, and this link has been explained by a redox cycling mechanism that induces oxidative stress. Here, we used a novel electrochemistry-based reverse engineering methodology to test the hypothesis that PQ can undergo reductive redox cycling with melanin. In this method, (i) an insoluble natural melanin (from Sepia melanin) and a synthetic model melanin (having a cysteinyldopamine-melanin core and dopamine-melanin shell) were entrapped in a nonconducting hydrogel film adjacent to an electrode, (ii) the film-coated electrode was immersed in solutions containing PQ (putative redox cycling reductant) and a redox cycling oxidant (ferrocene dimethanol), (iii) sequences of input potentials (i.e., voltages) were imposed to the underlying electrode to systematically engage reductive and oxidative redox cycling, and (iv) output response currents were analyzed for signatures of redox cycling. The response characteristics of the PQ-melanin systems to various input potential sequences support the hypothesis that PQ can directly donate electrons to melanin. This observation of PQ-melanin redox interactions demonstrates an association between two components that have been individually linked to oxidative stress and Parkinson's disease. Potentially, melanin's redox activity could be an important component in understanding the etiology of neurological disorders such as Parkinson's disease.

  8. Synthesis of Melanin-Like Pigments by Sporothrix schenckii In Vitro and during Mammalian Infection

    PubMed Central

    Morris-Jones, Rachael; Youngchim, Sirida; Gomez, Beatriz L.; Aisen, Phil; Hay, Roderick J.; Nosanchuk, Joshua D.; Casadevall, Arturo; Hamilton, Andrew J.

    2003-01-01

    Melanin has been implicated in the pathogenesis of several important human fungal pathogens. Existing data suggest that the conidia of the dimorphic fungal pathogen Sporothrix schenckii produce melanin or melanin-like compounds; in this study we aimed to confirm this suggestion and to demonstrate in vitro and in vivo production of melanin by yeast cells. S. schenckii grown on Mycosel agar produced visibly pigmented conidia, although yeast cells grown in brain heart infusion and minimal medium broth appeared to be nonpigmented macroscopically. However, treatment of both conidia and yeast cells with proteolytic enzymes, denaturant, and concentrated hot acid yielded dark particles similar in shape and size to the corresponding propagules, which were stable free radicals consistent with identification as melanins. Melanin particles extracted from S. schenckii yeast cells were used to produce a panel of murine monoclonal antibodies (MAbs) which labeled pigmented conidia, yeast cells, and the isolated particles. Tissue from hamster testicles infected with S. schenckii contained fungal cells that were labeled by melanin-binding MAbs, and digestion of infected hamster tissue yielded dark particles that were also reactive. Additionally, sera from humans with sporotrichosis contained antibodies that bound melanin particles. These findings indicate that S. schenckii conidia and yeast cells can produce melanin or melanin-like compounds in vitro and that yeast cells can synthesize pigment in vivo. Since melanin is an important virulence factor in other pathogenic fungi, this pigment may have a similar role in the pathogenesis of sporotrichosis. PMID:12819091

  9. Melanin: spin behaviour and implications for bioelectronic devices (Presentation Recording)

    NASA Astrophysics Data System (ADS)

    Meredith, Paul; Sheliakina, Margarita; Mostert, Bernard

    2015-10-01

    The melanins are a broad class of pigmentary macromolecules found through nature that perform a wide range of functions including photo-protection [1]. The most common melanin - the brown, black pigment eumelanin, has been much studied because of its role in melanoma and also for its functional material properties [2]. Synthetic eumelanin has been shown to be photoconductive in the solid state and also possess a water content dependent dark conductivity [3]. It is now well established that these electrical properties arise from hybrid ionic-electronic behaviour, leading to the proposition that melanins could be model biocompatible systems for ion-to-electron transduction in bioelectronics. In my talk, I will discuss the basic science behind these bioelectronics properties - electrical and optical. In this context I will also describe recent electron paramagnetic spin studies which isolate the role of the various chemical moieties responsible for the hybrid ionic-electronic behaviour. I will also highlight preliminary results on prototype melanin-based bioelectronics devices and discuss possible architectures to realise elements such as solid-state switches and transducers. [1] "The physical and chemical properties of eumelanin", P. Meredith and T. Sarna, Pigment Cell Research, 19(6), pp572-594 (2006). [2] "Electronic and optoelectronic materials and devices inspired by nature", P Meredith, C.J. Bettinger, M. Irimia-Vladu, A.B. Mostert and P.E. Schwenn, Reports on Progress in Physics, 76, 034501 (2013). [3] "Is melanin a semiconductor: humidity induced self doping and the electrical conductivity of a biopolymer", A.B. Mostert, B.J. Powell, F.L. Pratt, G.R. Hanson, T. Sarna, I.R. Gentle and P. Meredith, Proceedings of the National Academy of Sciences of the USA, 109(23), 8943-8947 (2012).

  10. Keratinocyte-derived laminin-332 protein promotes melanin synthesis via regulation of tyrosine uptake.

    PubMed

    Chung, Heesung; Jung, Hyejung; Lee, Jung-Hyun; Oh, Hye Yun; Kim, Ok Bin; Han, Inn-Oc; Oh, Eok-Soo

    2014-08-01

    Melanocytes, which produce the pigment melanin, are known to be closely regulated by neighboring keratinocytes. However, how keratinocytes regulate melanin production is unclear. Here we report that melanin production in melanoma cells (B16F10 and MNT-1) was increased markedly on a keratinocyte-derived extracellular matrix compared with a melanoma cell-derived extracellular matrix. siRNA-mediated reduction of keratinocyte-derived laminin-332 expression decreased melanin synthesis in melanoma cells, and laminin-332, but not fibronectin, enhanced melanin content and α-melanocyte-stimulating hormone-regulated melanin production in melanoma cells. Similar effects were observed in human melanocytes. Interestingly, however, laminin-332 did not affect the expression or activity of tyrosinase. Instead, laminin-332 promoted the uptake of extracellular tyrosine and, subsequently, increased intracellular levels of tyrosine in both melanocytes and melanoma cells. Taken together, these data strongly suggest that keratinocyte-derived laminin-332 contributes to melanin production by regulating tyrosine uptake.

  11. Decolorization of synthetic melanins by crude laccases of Lentinus polychrous Lév.

    PubMed

    Khammuang, Saranyu; Sarnthima, Rakrudee

    2013-01-01

    Melanins are complex natural pigments that darken the skin and are difficult to degrade. This study evaluated synthetic melanin decolorization by the crude laccase from fungus Lentinus polychrous in the absence and presence of selected redox mediators. The greatest melanin decolorization activity was 87 % at pH 6.5 within 3 h in the presence of 2,2-azinobis (3-ethylbenzothiazoline-6-sulfonate) diammonium salt (ABTS), whereas only about 22 % melanin decolorized at pH 5.0 in case of no mediator. The optimum temperatures for melanin decolorization in the absence and presence of ABTS were 55 and 35°C, respectively. Using a natural redox mediator, 1.0 mmol/L vanillin leads to 45 % melanin decolorization. Our results suggest the possibility of applying vanillin for L. polychrous laccase-catalyzed decolorization of melanin.

  12. Keratinocyte-derived Laminin-332 Protein Promotes Melanin Synthesis via Regulation of Tyrosine Uptake*

    PubMed Central

    Chung, Heesung; Jung, Hyejung; Lee, Jung-hyun; Oh, Hye Yun; Kim, Ok Bin; Han, Inn-Oc; Oh, Eok-Soo

    2014-01-01

    Melanocytes, which produce the pigment melanin, are known to be closely regulated by neighboring keratinocytes. However, how keratinocytes regulate melanin production is unclear. Here we report that melanin production in melanoma cells (B16F10 and MNT-1) was increased markedly on a keratinocyte-derived extracellular matrix compared with a melanoma cell-derived extracellular matrix. siRNA-mediated reduction of keratinocyte-derived laminin-332 expression decreased melanin synthesis in melanoma cells, and laminin-332, but not fibronectin, enhanced melanin content and α-melanocyte-stimulating hormone-regulated melanin production in melanoma cells. Similar effects were observed in human melanocytes. Interestingly, however, laminin-332 did not affect the expression or activity of tyrosinase. Instead, laminin-332 promoted the uptake of extracellular tyrosine and, subsequently, increased intracellular levels of tyrosine in both melanocytes and melanoma cells. Taken together, these data strongly suggest that keratinocyte-derived laminin-332 contributes to melanin production by regulating tyrosine uptake. PMID:24951591

  13. Comparative Transcriptome Analysis of Raccoon Dog Skin to Determine Melanin Content in Hair and Melanin Distribution in Skin

    PubMed Central

    Du, Zhanyu; Huang, Kai; Zhao, Jiaping; Song, Xingchao; Xing, Xiumei; Wu, Qiong; Zhang, Linbo; Xu, Chao

    2017-01-01

    The raccoon dog (Nyctereutes procyonoides) is an important canid fur-bearing animal species worldwide. Chinese raccoon dogs that present a white mutation, especially those with a white coat. Exploring melanin biosynthesis in the hair and skin of raccoon dogs is important for understanding the survival and evolutionary mechanisms of them. In this study, we measured the content of melanin in the hair of two types of raccoon dog and generated stained slices of skin tissue. The results indicated that melanin biosynthesis occurs in the wild-type (W) and white-type (B) raccoon dog skin, although less melanin is produced in B skin. We then sequenced the skin transcriptomes of W and B, compared the similarities and differences in expressed genes. A comparison of the gene expression showed 60 up-regulated genes and 127 down-regulated genes in B skin. We analyzed the unigenes and pathways related to the melanogenesis pathway and found that TYR, TYRP1, MC1R, SLC24a5, SLC45a2 and OCA2 were significantly down-regulated in B skin and these results were verified via qRT-PCR. We surmised that the phenotypic characteristics of the white mutation might be caused by the reduced expression of these genes and this finding provides new insights for future experiments in raccoon dogs. PMID:28098220

  14. The effect of melanin on iron associated decomposition of hydrogen peroxide.

    PubMed

    Pilas, B; Sarna, T; Kalyanaraman, B; Swartz, H M

    1988-01-01

    The effects of melanin on the iron-catalyzed decomposition of hydrogen peroxide to hydroxyl radicals and hydroxyl ions have been studied using electron spin resonance, spin trapping and visible light spectrophotometry. Melanin altered these reactions by several different mechanisms and consequently, depending on conditions, can significantly increase or decrease the yield of reactive products, including hydroxyl radicals. For low concentrations of ferrous ions, melanin decreased the yield of hydroxyl radicals due to binding of ferrous ions by melanin; ferrous ions bound to melanin did not decompose H2O2 efficiently. Melanins increased the rate of hydroxyl radical production if the predominant form of iron was ferric, due to the ability of melanin to reduce ferric to ferrous iron. Hydroxyl radical production in the presence of a strong chelator (e.g. EDTA) and melanin was greater than in the presence of a weak chelator (e.g. ADP) and melanin. Melanin also increased the rate of destruction of the DMPO-OH adduct.

  15. Laccase Gene Sh-lac Is Involved in the Growth and Melanin Biosynthesis of Scleromitrula shiraiana.

    PubMed

    Lǚ, Zhiyuan; Kang, Xin; Xiang, Zhonghuai; He, Ningjia

    2017-03-01

    Scleromitrula shiraiana causes the popcorn disease in mulberry trees resulting in severe economic losses. Previous studies have shown that melanin may play a vital role in establishing the pathogenicity of fungi. In the present study, we identified the melanin produced in S. shiraiana belongs to DHN melanin by gas chromatography-mass spectrometry, and cloned the laccase Sh-lac, a potential DHN melanin biosynthesis gene from S. shiraiana. We obtained two stable Sh-lac silenced transformants using RNAi, ilac-4 and 8 to elucidate the DHN melanin biosynthetic pathway in S. shiraiana. The melanin production of ilac-4 and ilac-8 was significantly reduced, and their vegetative growth was also suppressed. Results such as these led to a proposal that Sh-lac played a key role in DHN melanin formation in S. shiraiana and may function differentially with other melanin biosynthetic genes. The inhibition of melanin was accompanied by the decrease of oxalic acid and the adhesion of hyphae was impaired. Our results indicated that laccase was an important enzyme in the synthesis of melanin and might play a critical role in the pathogenicity of S. shiraiana.

  16. Isolation and characterization of melanin pigment from yesso scallop Patinopecten yessoensis

    NASA Astrophysics Data System (ADS)

    Sun, Xiujun; Wu, Biao; Zhou, Liqing; Liu, Zhihong; Dong, Yinghui; Yang, Aiguo

    2017-04-01

    Melanin is one of the essential compounds in the pigments of molluscan shells. However, the effects of melanin on color variations in molluscs are largely unknown. Our previous study suggests that Yesso scallop Patinopecten yessoensis might contain melanin pigment in the dark brown shell. We therefore isolated melanin from the pigmented shells using hydrochloric acid method, and characterized the types of melanin pigments by spectrophotometry. The purified melanin, which was verified by spectrophotometry scanning and HPLC analysis, showed the typical characteristics of melanin absorption spectra and HPLC chromatograms. The contents of pheomelanin and eumelanin in pigmented shells, which were determined by the linear standard curve of melanin at 405 nm and 350 nm absorbance, were 48.23 ± 1.350 and 157.65 ± 5.905 mg, respectively. The present results indicate that the brown-pigmented shells of scallops comprise approximately 76.6% of eumelanin and 23.4% of pheomelanin, which supports the presence of eumelanin-rich pigment in scallop shells. Therefore, the combination of hydrochloric acid extraction and spectrophotometric quantification is a rapid and efficient method to isolate and quantify melanin in shells. This will facilitate the melanin studies related to shell color polymorphism and the selective breeding of bivalves with different shell colors.

  17. Melanin and Melanin-Related Polymers as Materials with Biomedical and Biotechnological Applications-Cuttlefish Ink and Mussel Foot Proteins as Inspired Biomolecules.

    PubMed

    Solano, Francisco

    2017-07-18

    The huge development of bioengineering during the last years has boosted the search for new bioinspired materials, with tunable chemical, mechanical, and optoelectronic properties for the design of semiconductors, batteries, biosensors, imaging and therapy probes, adhesive hydrogels, tissue restoration, photoprotectors, etc. These new materials should complement or replace metallic or organic polymers that cause cytotoxicity and some adverse health effects. One of the most interesting biomaterials is melanin and synthetic melanin-related molecules. Melanin has a controversial molecular structure, dependent on the conditions of polymerization, and therefore tunable. It is found in animal hair and skin, although one of the common sources is cuttlefish (Sepia officinalis) ink. On the other hand, mussels synthesize adhesive proteins to anchor these marine animals to wet surfaces. Both melanin and mussel foot proteins contain a high number of catecholic residues, and their properties are related to these groups. Dopamine (DA) can easily polymerize to get polydopamine melanin (PDAM), that somehow shares properties with melanin and mussel proteins. Furthermore, PDAM can easily be conjugated with other components. This review accounts for the main aspects of melanin, as well as DA-based melanin-like materials, related to their biomedical and biotechnological applications.

  18. Melanin and Melanin-Related Polymers as Materials with Biomedical and Biotechnological Applications—Cuttlefish Ink and Mussel Foot Proteins as Inspired Biomolecules

    PubMed Central

    2017-01-01

    The huge development of bioengineering during the last years has boosted the search for new bioinspired materials, with tunable chemical, mechanical, and optoelectronic properties for the design of semiconductors, batteries, biosensors, imaging and therapy probes, adhesive hydrogels, tissue restoration, photoprotectors, etc. These new materials should complement or replace metallic or organic polymers that cause cytotoxicity and some adverse health effects. One of the most interesting biomaterials is melanin and synthetic melanin-related molecules. Melanin has a controversial molecular structure, dependent on the conditions of polymerization, and therefore tunable. It is found in animal hair and skin, although one of the common sources is cuttlefish (Sepia officinalis) ink. On the other hand, mussels synthesize adhesive proteins to anchor these marine animals to wet surfaces. Both melanin and mussel foot proteins contain a high number of catecholic residues, and their properties are related to these groups. Dopamine (DA) can easily polymerize to get polydopamine melanin (PDAM), that somehow shares properties with melanin and mussel proteins. Furthermore, PDAM can easily be conjugated with other components. This review accounts for the main aspects of melanin, as well as DA-based melanin-like materials, related to their biomedical and biotechnological applications. PMID:28718807

  19. Detection of antibodies against Paracoccidioides brasiliensis melanin in in vitro and in vivo studies during infection.

    PubMed

    Urán, Martha E; Nosanchuk, Joshua D; Restrepo, Angela; Hamilton, Andrew J; Gómez, Beatriz L; Cano, Luz E

    2011-10-01

    Several cell wall constituents, including melanins or melanin-like compounds, have been implicated in the pathogenesis of a wide variety of microbial diseases caused by diverse species of pathogenic bacteria, fungi, and helminthes. Among these microorganisms, the dimorphic fungal pathogen Paracoccidioides brasiliensis produces melanin in its conidial and yeast forms. In the present study, melanin particles from P. brasiliensis were injected into BALB/c mice in order to produce monoclonal antibodies (MAbs). We identified five immunoglobulin G1 (IgG1) κ-chain and four IgM melanin-binding MAbs. The five IgG1 κ-chain isotypes are the first melanin-binding IgG MAbs ever reported. The nine MAbs labeled P. brasiliensis conidia and yeast cells both in vitro and in pulmonary tissues. The MAbs cross-reacted with melanin-like purified particles from other fungi and also with commercial melanins, such as synthetic and Sepia officinalis melanin. Melanization during paracoccidioidomycosis (PCM) was also further supported by the detection of IgG antibodies reactive to melanin from P. brasiliensis conidia and yeast in sera and bronchoalveolar lavage fluids from P. brasiliensis-infected mice, as well as in sera from human patients with PCM. Serum specimens from patients with other mycoses were also tested for melanin-binding antibodies by enzyme-linked immunosorbent assay, and cross-reactivities were detected for melanin particles from different fungal sources. These results suggest that melanin from P. brasiliensis is an immunologically active fungal structure that activates a strong IgG humoral response in humans and mice.

  20. Molecular preservation of the pigment melanin in fossil melanosomes.

    PubMed

    Lindgren, Johan; Uvdal, Per; Sjövall, Peter; Nilsson, Dan E; Engdahl, Anders; Schultz, Bo Pagh; Thiel, Volker

    2012-05-08

    Fossil feathers, hairs and eyes are regularly preserved as carbonized traces comprised of masses of micrometre-sized bodies that are spherical, oblate or elongate in shape. For a long time, these minute structures were regarded as the remains of biofilms of keratinophilic bacteria, but recently they have been reinterpreted as melanosomes; that is, colour-bearing organelles. Resolving this fundamental difference in interpretation is crucial: if endogenous then the fossil microbodies would represent a significant advancement in the fields of palaeontology and evolutionary biology given, for example, the possibility to reconstruct integumentary colours and plumage colour patterns. It has previously been shown that certain trace elements occur in fossils as organometallic compounds, and hence may be used as biomarkers for melanin pigments. Here we expand this knowledge by demonstrating the presence of molecularly preserved melanin in intimate association with melanosome-like microbodies isolated from an argentinoid fish eye from the early Eocene of Denmark.

  1. Structure and Function of Iron-Loaded Synthetic Melanin

    SciTech Connect

    Li, Yiwen; Xie, Yijun; Wang, Zhao; Zang, Nanzhi; Carniato, Fabio; Huang, Yuran; Andolina, Christopher M.; Parent, Lucas R.; Ditri, Treffly B.; Walter, Eric D.; Botta, Mauro; Rinehart, Jeffrey D.; Gianneschi, Nathan C.

    2016-11-22

    We describe a synthetic method for increasing and controlling the iron loading of synthetic melanin nanoparticles and use the resulting materials to perform a systematic quantitative investigation on their structure- property relationship. A comprehensive analysis by magnetometry, electron paramagnetic resonance, and nuclear magnetic relaxation dispersion reveals the complexities of their magnetic behavior and how these intraparticle magnetic interactions manifest in useful material properties such as their performance as MRI contrast agents. This analysis allows predictions of the optimal iron loading through a quantitative modeling of antiferromagnetic coupling that arises from proximal iron ions. This study provides a detailed understanding of this complex class of synthetic biomaterials and gives insight into interactions and structures prevalent in naturally occurring melanins.

  2. Melanin-based colour polymorphism responding to climate change.

    PubMed

    Roulin, Alexandre

    2014-11-01

    Climate warming leads to a decrease in biodiversity. Organisms can deal with the new prevailing environmental conditions by one of two main routes, namely evolving new genetic adaptations or through phenotypic plasticity to modify behaviour and physiology. Melanin-based colouration has important functions in animals including a role in camouflage and thermoregulation, protection against UV-radiation and pathogens and, furthermore, genes involved in melanogenesis can pleiotropically regulate behaviour and physiology. In this article, I review the current evidence that differently coloured individuals are differentially sensitive to climate change. Predicting which of dark or pale colour variants (or morphs) will be more penalized by climate change will depend on the adaptive function of melanism in each species as well as how the degree of colouration covaries with behaviour and physiology. For instance, because climate change leads to a rise in temperature and UV-radiation and dark colouration plays a role in UV-protection, dark individuals may be less affected from global warming, if this phenomenon implies more solar radiation particularly in habitats of pale individuals. In contrast, as desertification increases, pale colouration may expand in those regions, whereas dark colourations may expand in regions where humidity is predicted to increase. Dark colouration may be also indirectly selected by climate warming because genes involved in the production of melanin pigments confer resistance to a number of stressful factors including those associated with climate warming. Furthermore, darker melanic individuals are commonly more aggressive than paler conspecifics, and hence they may better cope with competitive interactions due to invading species that expand their range in northern latitudes and at higher altitudes. To conclude, melanin may be a major component involved in adaptation to climate warming, and hence in animal populations melanin-based colouration is

  3. Snapshot RGB mapping of skin melanin and hemoglobin

    NASA Astrophysics Data System (ADS)

    Spigulis, Janis; Oshina, Ilze

    2015-05-01

    The concept of snapshot red-green-blue (RGB) multispectral imaging was applied for skin chromophore mapping. Three monochromatic spectral images have been extracted from a single RGB image dataset at simultaneous illumination of skin by 473-, 532-, and 659-nm laser lines. The spectral images were further transformed into distribution maps of skin melanin, oxyhemoglobin, and deoxyhemoglobin, related to pigmented and vascular skin malformations. The performance and clinical potential of the proposed technique are discussed.

  4. Chemosorption of radiometals of interest to nuclear medicine by synthetic melanins

    PubMed Central

    Howell, R. C.; Schweitzer, A. D.; Casadevall, A.; Dadachova, E. A.

    2008-01-01

    Introduction Melanins are high molecular weight pigments that are ubiquitous in nature and can also be synthesized in the laboratory from the variety of precursors. Melanins possess numerous interesting physico-chemical characteristics including electromagnetic radiation absorption properties and the ability to chelate metals. We have recently reported that melanin has remarkable ionizing radiation shielding properties, possibly because it can interact with photons via Compton scattering. We hypothesized that, if administered internally, in addition to radiation shielding, melanin could play a beneficial role by scavenging various radionuclides. Methods Three melanins were synthesized from dopamine, 3,4-dihydroxyphenylalanine (L-Dopa) and from combination of L-Cysteine and L-Dopa. For control synthetic melanin made from tyrosine polymerization (Sigma) was used. Melanins were characterized by elemental analysis. The chemosorption of 111In, 225Ac and 213Bi by melanins was studied at 37°C for up to 48 hrs. Results The C to N molar ratios for dopamine, L-Dopa and tyrosine melanins were very close at 7.92, 8.39, and 8.48, respectively, while in mixed L-cysteine/L-Dopa melanin that ratio was much lower at 3.63. This mixed melanin also contained 22.33% sulfur, thus confirming incorporation of S-containing motifs into its structure. Dopamine, L-Dopa and tyrosine melanins were very similar in their ability to decrease the activity of 111In, 225Ac and 213Bi and their radioactive daughters in the supernatants more than 10-fold in comparison with the starting levels while mixed L-cysteine/L-Dopa melanin was able to chemosorb only 111In. Conclusions We have demonstrated that synthetic melanins made of diverse precursors can chemosorb 111In, 213Bi and 225Ac with dopamine, L-dopa and tyrosine melanins being the most efficient towards all three of these radionuclides. Such properties of synthetic melanins can contribute to the development of the novel melanin

  5. Flavonoids and Melanins: a common strategy across two kingdoms.

    PubMed

    Carletti, Giorgia; Nervo, Giuseppe; Cattivelli, Luigi

    2014-01-01

    Ultraviolet (UV) radiations alter a number of metabolic functions in vivant. They produce damages to lipids, nucleic acids and proteins, generating reactive oxygen species such as singlet oxygen (O2), hydroxyl radical (HO) and superoxide anion (O2 (-)). Plants and animals, after their water emersion, have developed biochemical mechanisms to protect themselves from that environmental threat through a common strategy. Melanins in animals and flavonoids in plants are antioxidant pigments acting as free radical scavenging mechanisms. Both are phenol compounds constitutively synthesized and enhanced after exposure to UV rays, often conferring a red-brown-dark tissue pigmentation. Noteworthy, beside anti-oxidant scavenging activity, melanins and flavonoids have acquired secondary functions that, both in plants and animals, concern reproductions and fitness. Plants highly pigmented are more resistant to biotic and abiotic stresses. Darker wild vertebrates are generally more aggressive, sexually active and resistant to stress than lighter individuals. Flavonoids have been associated with signal attraction between flowers and insects and with plant-plant interaction. Melanin pigmentation has been proposed as trait in bird communication, acting as honest signals of quality. This review shows how the molecular mechanisms leading to tissue pigmentation have many functional analogies between plants and animals and how their origin lies in simpler organisms such as Cyanobacteria. Comparative studies between plant and animal kingdoms can reveal new insight of the antioxidant strategies in vivant.

  6. Flavonoids and Melanins: A Common Strategy across Two Kingdoms

    PubMed Central

    Carletti, Giorgia; Nervo, Giuseppe; Cattivelli, Luigi

    2014-01-01

    Ultraviolet (UV) radiations alter a number of metabolic functions in vivant. They produce damages to lipids, nucleic acids and proteins, generating reactive oxygen species such as singlet oxygen (O2), hydroxyl radical (HO) and superoxide anion (O2-). Plants and animals, after their water emersion, have developed biochemical mechanisms to protect themselves from that environmental threat through a common strategy. Melanins in animals and flavonoids in plants are antioxidant pigments acting as free radical scavenging mechanisms. Both are phenol compounds constitutively synthesized and enhanced after exposure to UV rays, often conferring a red-brown-dark tissue pigmentation. Noteworthy, beside anti-oxidant scavenging activity, melanins and flavonoids have acquired secondary functions that, both in plants and animals, concern reproductions and fitness. Plants highly pigmented are more resistant to biotic and abiotic stresses. Darker wild vertebrates are generally more aggressive, sexually active and resistant to stress than lighter individuals. Flavonoids have been associated with signal attraction between flowers and insects and with plant-plant interaction. Melanin pigmentation has been proposed as trait in bird communication, acting as honest signals of quality. This review shows how the molecular mechanisms leading to tissue pigmentation have many functional analogies between plants and animals and how their origin lies in simpler organisms such as Cyanobacteria. Comparative studies between plant and animal kingdoms can reveal new insight of the antioxidant strategies in vivant. PMID:25516714

  7. Imaging melanin by two-photon absorption microscopy

    NASA Astrophysics Data System (ADS)

    Ye, Tong; Yurtsever, Gunay; Fischer, Martin; Simon, John D.; Warren, Warren S.

    2006-02-01

    Multiphoton excitation fluorescence microscopy has proven to be a powerful method for non-invasive, in vivo, thick tissue imaging with molecular specificity. However, many important endogenous biomolecules do not fluoresce (NAD) or fluoresce with low efficiency (Melanin). In this report femtosecond pulse shaping methods are used to measure two-photon absorption (TPA) directly with very high sensitivity. Combining with the laser scanning microscope, this Two-photon Absorption Microscopy (TPAM) retains the penetration and localization advantages of two-photon fluorescence microscopy and permits direct observation of important endogenous molecular markers (melanin or hemoglobin) which are invisible in multiphoton fluorescence microscopy. We have demonstrated here for the first time that TPAM can successfully and more efficiently image melanoma cells and tissues and provide a good melanin contrast in optical sectioning of the melanoma lesions which are comparable to pathological histology. Combining with the two-photon fluorescence images acquired simultaneously, the distribution patterns of the melanocytes and their intratissue behavior could be studied without cutting the lesions from patients. TPAM will undoubtedly find the applications in the clinical diagnosis and biomedical research.

  8. Hesperetin induces melanin production in adult human epidermal melanocytes.

    PubMed

    Usach, Iris; Taléns-Visconti, Raquel; Magraner-Pardo, Lorena; Peris, José-Esteban

    2015-06-01

    One of the major sources of flavonoids for humans are citrus fruits, hesperidin being the predominant flavonoid. Hesperetin (HSP), the aglycon of hesperidin, has been reported to provide health benefits such as antioxidant, anti-inflammatory and anticarcinogenic effects. However, the effect of HSP on skin pigmentation is not clear. Some authors have found that HSP induces melanogenesis in murine B16-F10 melanoma cells, which, if extrapolated to in vivo conditions, might protect skin against photodamage. Since the effect of HSP on normal melanocytes could be different to that observed on melanoma cells, the described effect of HSP on murine melanoma cells has been compared to the effect obtained using normal human melanocytes. HSP concentrations of 25 and 50 µM induced melanin synthesis and tyrosinase activity in human melanocytes in a concentration-dependent manner. Compared to control melanocytes, 25 µM HSP increased melanin production and tyrosinase activity 1.4-fold (p < 0.01) and 1.1-fold (p < 0.01), respectively, and the corresponding increases in the case of 50 µM HSP were 1.9-fold (p < 0.001) and 1.3-fold (p < 0.001). Therefore, HSP could be considered a valuable photoprotective substance if its capacity to increase melanin production in human melanocyte cultures could be reproduced on human skin.

  9. Genetic Basis of Melanin Pigmentation in Butterfly Wings.

    PubMed

    Zhang, Linlin; Martin, Arnaud; Perry, Michael W; van der Burg, Karin R L; Matsuoka, Yuji; Monteiro, Antónia; Reed, Robert D

    2017-04-01

    Despite the variety, prominence, and adaptive significance of butterfly wing patterns, surprisingly little is known about the genetic basis of wing color diversity. Even though there is intense interest in wing pattern evolution and development, the technical challenge of genetically manipulating butterflies has slowed efforts to functionally characterize color pattern development genes. To identify candidate wing pigmentation genes, we used RNA sequencing to characterize transcription across multiple stages of butterfly wing development, and between different color pattern elements, in the painted lady butterfly Vanessa cardui This allowed us to pinpoint genes specifically associated with red and black pigment patterns. To test the functions of a subset of genes associated with presumptive melanin pigmentation, we used clustered regularly interspaced short palindromic repeats (CRISPR)/Cas9 genome editing in four different butterfly genera. pale, Ddc, and yellow knockouts displayed reduction of melanin pigmentation, consistent with previous findings in other insects. Interestingly, however, yellow-d, ebony, and black knockouts revealed that these genes have localized effects on tuning the color of red, brown, and ochre pattern elements. These results point to previously undescribed mechanisms for modulating the color of specific wing pattern elements in butterflies, and provide an expanded portrait of the insect melanin pathway. Copyright © 2017 by the Genetics Society of America.

  10. Femtosecond two-photon-excited fluorescence of melanin

    NASA Astrophysics Data System (ADS)

    Teuchner, Klaus; Mueller, Susanne; Freyer, Wolfgang; Leupold, Dieter; Altmeyer, Peter; Stuecker, Markus; Hoffmann, Klaus

    2003-02-01

    Spectral and time-resolved fluorescence studies of different eumelanins (natural, synthetic, enzymatic) in solution have been carried out by two-photon excitation at 800 nm, using 80 fs pulses with photon flux densities <= 1027 cm-2.s-1. Whereas all samples show monotonously decreasing absorption between near UV and near IR, their fluorescence behavior indicates strong heterogeneity. With respect to the also measured one-photon excited fluorescence (OPF) of melanin at 400 nm, the overall spectral shape of the two-photon excited fluorescence (TPF) is red-shifted. Both OPF and TPF exhibit three-exponential decay with a shortest component # 200 ps. As is also shown, the fluorescence properties of melanin are dependent on the micro-environment. This allows the hypothesis, that the process of malignant transformation in skin tissue could be reflected in the fluorescence, provided the melanin in skin is selectively excited. The latter is realized by the described stepwise absorption of two 800 nm photons. In this way, indeed characteristic differences between the TPF spectra of healthy tissue, nevus cell nevi and malignant melanoma have been found.

  11. Melanin-Associated Synthesis of SERS-Active Nanostructures and the Application for Monitoring of Intracellular Melanogenesis

    PubMed Central

    Dong, Haixin; Liu, Zhiming; Zhong, Huiqing; Yang, Hui; Zhou, Yan; Hou, Yuqing; Long, Jia; Lin, Jin; Guo, Zhouyi

    2017-01-01

    Melanin plays an indispensable role in the human body. It serves as a biological reducer for the green synthesis of precious metal nanoparticles. Melanin–Ag nanocomposites were successfully produced which exhibited very strong surface-enhanced Raman scattering (SERS) effect because of the reducibility property of melanin. A melanin–Ag composite structure was synthesized in situ in melanin cells, and SERS technique was performed for the rapid imaging and quantitative assay of intracellular melanin. This imaging technique was also used to successfully trace the formation and secretion of intracellular melanin after stimulation with melanin-stimulating hormones. Based on the self-reducing property of melanin, the proposed SERS imaging method can provide potentially powerful analytical detection tools to study the biological functions of melanin and to prevent and cure melanin-related diseases. PMID:28336903

  12. On the structure of human hair melanins from an infrared spectroscopy analysis of their interactions with Cu 2+ ions

    NASA Astrophysics Data System (ADS)

    Bilińska, Barbara

    2001-10-01

    Melanins were isolated from dark and red human hair and complexed with copper ions at various pH values in a complexing medium. IR spectra of melanins and their Cu 2+-complexes for pellets with KBr were obtained. The IR spectra indicate that Cu 2+ ions bound to melanins are fixed by different carboxyl and hydroxyl (phenolic and/or alcoholic) groups in the macromolecule. From these results it is concluded that, generally, melanin carboxyl groups are responsible for interactions of metal ions with the melanin molecule. Complexes of melanins isolated from dark and red human hair show structural differences when analysed by IR spectroscopy. Conclusions from these investigations assist in the differentiation of structures of analysed hair melanins. IR spectral analysis of melanin samples and their complexes suggest that melanin samples obtained from red hair may contain eumelanin.

  13. Sub-nm 3D observation of human hair melanin by high-voltage STEM.

    PubMed

    Imai, Takehito; Higuchi, Kimitaka; Yamamoto, Yuta; Arai, Shigeo; Nakano, Takashi; Tanaka, Nobuo

    2016-04-01

    The ultrastructure of melanin granules in human hair was studied using 1,000 kV high-voltage scanning transmission electron microscopy to successfully reconstruct three-dimensional images of the whole melanin granule. It was revealed that the melanin granule was composed of a membrane-like outer structure that included many spherical vesicles, and an inner matrix containing a sheet-like structure in the elongated direction of the melanin granule and a sheet-like arrays structure in the cross direction. The outer structure of the melanin granule was maintained even after exposure to hair-bleaching agents to decompose the melanin granule, suggesting that the outer structure was a highly robust structure and composition compared with the inner matrix .

  14. Melanin from the nitrogen-fixing bacterium Azotobacter chroococcum: a spectroscopic characterization.

    PubMed

    Banerjee, Aulie; Supakar, Subhrangshu; Banerjee, Raja

    2014-01-01

    Melanins, the ubiquitous hetero-polymer pigments found widely dispersed among various life forms, are usually dark brown/black in colour. Although melanins have variety of biological functions, including protection against ultraviolet radiation of sunlight and are used in medicine, cosmetics, extraction of melanin from the animal and plant kingdoms is not an easy task. Using complementary physicochemical techniques (i.e. MALDI-TOF, FTIR absorption and cross-polarization magic angle spinning solid-state (13)C NMR), we report here the characterization of melanins extracted from the nitrogen-fixing non-virulent bacterium Azotobacter chroococcum, a safe viable source. Moreover, considering dihydroxyindole moiety as the main constituent, an effort is made to propose the putative molecular structure of the melanin hetero-polymer extracted from the bacterium. Characterization of the melanin obtained from Azotobacter chroococcum would provide an inspiration in extending research activities on these hetero-polymers and their use as protective agent against UV radiation.

  15. Comparative EPR studies of free radicals in melanin synthesized by Bacillus weihenstephanensis soil strains

    NASA Astrophysics Data System (ADS)

    Zdybel, Magdalena; Pilawa, Barbara; Drewnowska, Justyna M.; Swiecicka, Izabela

    2017-07-01

    EPR spectroscopy was used to examine the properties of and free radical concentrations in atypical water-soluble melanin-like pigments from Bacillus weihenstephanensis strains. The same EPR spectral shape was observed in bacterial melanins as in eumelanin. The EPR lines were homogeneously broadened. Continuous microwave saturation of the EPR lines indicated slow spin-lattice relaxation processes in the samples. Strong dipolar interactions characterized the tested melanin samples. Higher free radical concentrations were found in bacterial melanin than in synthetic melanin. The free radical concentrations in melanin from B. weihenstephanensis increased in the following order: strain JAS 81/4 < JAS 83/3 < JAS 86/1 < JAS 39/1.

  16. The contribution of the melanin pathway to overall body pigmentation during ontogenesis of Periplaneta americana.

    PubMed

    Lemonds, Thomas R; Liu, Jin; Popadić, Aleksandar

    2016-08-01

    The most prominent colors observed in insects are black or brown, whose production is attributed to the melanin pathway. At present, though, the contribution of this pathway to overall body pigmentation throughout ontogenesis is still lacking. To address this question we examined the roles of 2 key melanin genes (TH and DDC), in embryonic and postembryonic development of the American cockroach, Periplaneta americana. Our results show that the melanin pathway does not contribute to the light brown coloration observed in the first nymphs. However, the dark brown coloration in mid nymphs and adults is produced solely from the melanin pathway. In addition, the DDC RNAi results reveal that it is dopamine melanin, not DOPA melanin, acts as the main contributor in this process. Overall, present study provides a new insight into insect pigmentation suggesting that genetic mechanisms of coloration can change during ontogenesis. Future studies of additional basal insect lineages will be required to assess in more details the generality of this phenomenon.

  17. Role of semiconductivity and ion transport in the electrical conduction of melanin

    PubMed Central

    Mostert, Albertus B.; Powell, Benjamin J.; Pratt, Francis L.; Hanson, Graeme R.; Sarna, Tadeusz; Gentle, Ian R.; Meredith, Paul

    2012-01-01

    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. PMID:22615355

  18. Role of semiconductivity and ion transport in the electrical conduction of melanin.

    PubMed

    Mostert, Albertus B; Powell, Benjamin J; Pratt, Francis L; Hanson, Graeme R; Sarna, Tadeusz; Gentle, Ian R; Meredith, Paul

    2012-06-05

    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.

  19. Solution structure of copper ion-induced molecular aggregates of tyrosine melanin.

    PubMed

    Gallas, J M; Littrell, K C; Seifert, S; Zajac, G W; Thiyagarajan, P

    1999-08-01

    Melanin, the ubiquitous biological pigment, provides photoprotection by efficient filtration of light and also by its antioxidant behavior. In solutions of synthetic melanin, both optical and antioxidant behavior are affected by the aggregation states of melanin. We have utilized small-angle x-ray and neutron scattering to determine the molecular dimensions of synthetic tyrosine melanin in its unaggregated state in D(2)O and H(2)O to study the structure of melanin aggregates formed in the presence of copper ions at various copper-to-melanin molar ratios. In the absence of copper ions, or at low copper ion concentrations, tyrosine melanin is present in solution as a sheet-like particle with a mean thickness of 12.5 A and a lateral extent of approximately 54 A. At a copper-to-melanin molar ratio of 0.6, melanin aggregates to form long, rod-like structures with a radius of 32 A. At a higher copper ion concentration, with a copper-to-melanin ratio of 1.0, these rod-like structures further aggregate, forming sheet-like structures with a mean thickness of 51 A. A change in the charge of the ionizable groups induced by the addition of copper ions is proposed to account for part of the aggregation. The data also support a model for the copper-induced aggregation of melanin driven by pi stacking assisted by peripheral Cu(2+) complexation. The relationship between our results and a previous hypothesis for reduced cellular damage from bound-to-melanin redox metal ions is also discussed.

  20. Ionizing Radiation Changes the Electronic Properties of Melanin and Enhances the Growth of Melanized Fungi

    PubMed Central

    Dadachova, Ekaterina; Bryan, Ruth A.; Huang, Xianchun; Moadel, Tiffany; Schweitzer, Andrew D.; Aisen, Philip; Nosanchuk, Joshua D.; Casadevall, Arturo

    2007-01-01

    Background Melanin pigments are ubiquitous in nature. Melanized microorganisms are often the dominating species in certain extreme environments, such as soils contaminated with radionuclides, suggesting that the presence of melanin is beneficial in their life cycle. We hypothesized that ionizing radiation could change the electronic properties of melanin and might enhance the growth of melanized microorganisms. Methodology/Principal Findings Ionizing irradiation changed the electron spin resonance (ESR) signal of melanin, consistent with changes in electronic structure. Irradiated melanin manifested a 4-fold increase in its capacity to reduce NADH relative to non-irradiated melanin. HPLC analysis of melanin from fungi grown on different substrates revealed chemical complexity, dependence of melanin composition on the growth substrate and possible influence of melanin composition on its interaction with ionizing radiation. XTT/MTT assays showed increased metabolic activity of melanized C. neoformans cells relative to non-melanized cells, and exposure to ionizing radiation enhanced the electron-transfer properties of melanin in melanized cells. Melanized Wangiella dermatitidis and Cryptococcus neoformans cells exposed to ionizing radiation approximately 500 times higher than background grew significantly faster as indicated by higher CFUs, more dry weight biomass and 3-fold greater incorporation of 14C-acetate than non-irradiated melanized cells or irradiated albino mutants. In addition, radiation enhanced the growth of melanized Cladosporium sphaerospermum cells under limited nutrients conditions. Conclusions/Significance Exposure of melanin to ionizing radiation, and possibly other forms of electromagnetic radiation, changes its electronic properties. Melanized fungal cells manifested increased growth relative to non-melanized cells after exposure to ionizing radiation, raising intriguing questions about a potential role for melanin in energy capture and

  1. Current Understanding of the Binding Sites, Capacity, Affinity, and Biological Significance of Metals in Melanin

    PubMed Central

    Hong, Lian; Simon, John D.

    2008-01-01

    Metal chelation is often invoked as one of the main biological functions of melanin. In order to understand the interaction between metals and melanin, extensive studies have been carried out to determine the nature of the metal binding sites, binding capacity and affinity. These data are central to efforts aimed at elucidating the role metal binding plays in determining the physical, structural, biological, and photochemical properties of melanin. This article examines the current state of understanding of this field. PMID:17580858

  2. Dermal melanin concentration of yellow perch Perca flavescens in relation to water transparency.

    PubMed

    Rheault, G; Langevin, M; Cabana, G; Glémet, H

    2015-11-01

    A positive relationship was observed between Secchi disc depth and dermal melanin concentration in yellow perch Perca flavescens sampled from 11 humic lakes located on the Canadian Shield in southern Quebec (Canada). Secchi disc depth explained 23% of the variations of dermal melanin concentration. Secchi disc depth and thus water transparency appear to have a positive influence on melanin production in the dermis of P. flavescens.

  3. Solution structure of copper ion-induced molecular aggregates of tyrosine melanin.

    PubMed Central

    Gallas, J M; Littrell, K C; Seifert, S; Zajac, G W; Thiyagarajan, P

    1999-01-01

    Melanin, the ubiquitous biological pigment, provides photoprotection by efficient filtration of light and also by its antioxidant behavior. In solutions of synthetic melanin, both optical and antioxidant behavior are affected by the aggregation states of melanin. We have utilized small-angle x-ray and neutron scattering to determine the molecular dimensions of synthetic tyrosine melanin in its unaggregated state in D(2)O and H(2)O to study the structure of melanin aggregates formed in the presence of copper ions at various copper-to-melanin molar ratios. In the absence of copper ions, or at low copper ion concentrations, tyrosine melanin is present in solution as a sheet-like particle with a mean thickness of 12.5 A and a lateral extent of approximately 54 A. At a copper-to-melanin molar ratio of 0.6, melanin aggregates to form long, rod-like structures with a radius of 32 A. At a higher copper ion concentration, with a copper-to-melanin ratio of 1.0, these rod-like structures further aggregate, forming sheet-like structures with a mean thickness of 51 A. A change in the charge of the ionizable groups induced by the addition of copper ions is proposed to account for part of the aggregation. The data also support a model for the copper-induced aggregation of melanin driven by pi stacking assisted by peripheral Cu(2+) complexation. The relationship between our results and a previous hypothesis for reduced cellular damage from bound-to-melanin redox metal ions is also discussed. PMID:10423458

  4. Production and cytotoxicity of extracellular insoluble and droplets of soluble melanin by Streptomyces lusitanus DMZ-3.

    PubMed

    Madhusudhan, D N; Mazhari, Bi Bi Zainab; Dastager, Syed G; Agsar, Dayanand

    2014-01-01

    A Streptomyces lusitanus DMZ-3 strain with potential to synthesize both insoluble and soluble melanins was detected. Melanins are quite distinguished based on their solubility for varied biotechnological applications. The present investigation reveals the enhanced production of insoluble and soluble melanins in tyrosine medium by a single culture. Streptomyces lusitanus DMZ-3 was characterized by 16S rRNA gene analysis. An enhanced production of 5.29 g/L insoluble melanin was achieved in a submerged bioprocess following response surface methodology. Combined interactive effect of temperature (50°C), pH (8.5), tyrosine (2.0 g/L), and beef extract (0.5 g/L) were found to be critical variables for enhanced production in central composite design analysis. An optimized indigenous slant culture system was an innovative approach for the successful production (264 mg/L) of pure soluble melanin from the droplets formed on the surface of the culture. Both insoluble and soluble melanins were confirmed and characterized by Chemical, reactions, UV, FTIR, and TLC analysis. First time, cytotoxic study of melanin using brine shrimps was reported. Maximum cytotoxic activity of soluble melanin was Lc50-0.40 µg/mL and insoluble melanin was Lc50-0.80 µg/mL.

  5. Isolation and characterization of biologically active melanin from Actinoalloteichus sp. MA-32.

    PubMed

    Manivasagan, Panchanathan; Venkatesan, Jayachandran; Senthilkumar, Kalimuthu; Sivakumar, Kannan; Kim, Se-Kwon

    2013-07-01

    Melanins are enigmatic pigments and biological macromolecules that are produced by a wide variety of microorganisms including several species of bacteria and fungi. The present study was carried out on isolation and characterization of melanin from marine actinobacteria, Actinoalloteichus sp. MA-32. Medium composition and culture conditions for the melanin production by Actinoalloteichus sp. MA-32 were optimized using two statistical methods: Plackett-Burman design applied to find the key ingredients and conditions for the best yield of melanin production and central composite design used to optimize the concentration of the four significant variables: glycerol, L-tyrosine, NaCl and trace salt solution. The melanin was optimally active at pH 7-9 and temperature 45-60°C and it was most stable up to pH 11 and 4% of NaCl concentration. Melanin was examined by UV-vis absorption spectroscopy and infrared spectrometry. Melanin has potential antibacterial activity as it showed greater antagonistic and it has a strong antioxidant potential observed in the in vitro evaluation of its DPPH radical-scavenging activity, superoxide radical-scavenging activity, nitric oxide-scavenging activity, reducing power and metal chelating activity. The observed activities indicate that melanin might be a novel potential antioxidant. This study suggested that the melanin could potentially be used as a natural antioxidant in the food, cosmetic and pharmaceutical industries.

  6. Production of natural edible melanin by Auricularia auricula and its physicochemical properties.

    PubMed

    Sun, Shujing; Zhang, Xiaojuan; Chen, Wenxing; Zhang, Liaoyuan; Zhu, Hu

    2016-04-01

    Fermentation conditions of natural edible melanin by Auricularia auricula were optimized to obtain a high melanin yield and physicochemical properties of melanin were firstly investigated. The results indicated that yeast extract, tyrosine and lactose have significant effects on melanin production. Under the proposed optimized conditions, the melanin experimental yield (2.97 g/L) closely matched the value (3.04 g/L) predicted by the second-order model, which provided a statistically prediction of media in submerged fermentation of A. auricula. The yield achieved was 2.14-fold higher compared to the control. It was firstly revealed that tyrosine could stimulate melanin synthesis in A. auricula. The results showed that this melanin had better thermostability and light resistance, and its solubility was relatively high under alkaline conditions. Zn(2+) and Cu(2+) could result in melanin precipitation. The results should be useful for the efficient production of melanin and enable numerous applications in food, cosmetics, pharmacology, medicines and other fields.

  7. Production and Cytotoxicity of Extracellular Insoluble and Droplets of Soluble Melanin by Streptomyces lusitanus DMZ-3

    PubMed Central

    Madhusudhan, D. N.; Mazhari, Bi Bi Zainab; Dastager, Syed G.

    2014-01-01

    A Streptomyces lusitanus DMZ-3 strain with potential to synthesize both insoluble and soluble melanins was detected. Melanins are quite distinguished based on their solubility for varied biotechnological applications. The present investigation reveals the enhanced production of insoluble and soluble melanins in tyrosine medium by a single culture. Streptomyces lusitanus DMZ-3 was characterized by 16S rRNA gene analysis. An enhanced production of 5.29 g/L insoluble melanin was achieved in a submerged bioprocess following response surface methodology. Combined interactive effect of temperature (50°C), pH (8.5), tyrosine (2.0 g/L), and beef extract (0.5 g/L) were found to be critical variables for enhanced production in central composite design analysis. An optimized indigenous slant culture system was an innovative approach for the successful production (264 mg/L) of pure soluble melanin from the droplets formed on the surface of the culture. Both insoluble and soluble melanins were confirmed and characterized by Chemical, reactions, UV, FTIR, and TLC analysis. First time, cytotoxic study of melanin using brine shrimps was reported. Maximum cytotoxic activity of soluble melanin was Lc50-0.40 µg/mL and insoluble melanin was Lc50-0.80 µg/mL. PMID:24839603

  8. Dependence of third-harmonic generation on melanin concentration in solution

    NASA Astrophysics Data System (ADS)

    Su, Tung-Yu; Liao, Chien-Sheng; Yang, Chih-Yuan; Zhuo, Zong-Yan; Chen, Szu-Yu; Chu, Shi-Wei

    2011-03-01

    In this study, we performed theoretical analysis and experimental measurement of third harmonic generation (THG) in melanin solution with different concentrations. As predicted by theory, only THG at glass/solution interface was observed due to Guoy phase shift effect. We have shown that this interfacial THG intensity is strongly affected by index matching condition between the two media, leading to minimal THG at a certain melanin concentration. By fitting the dependence of THG intensity versus melanin concentration, linear and nonlinear electric susceptibilities of melanin are obtained, providing a valuable tool to characterize optical properties of biological molecules.

  9. Non-contact assessment of melanin distribution via multispectral temporal illumination coding

    NASA Astrophysics Data System (ADS)

    Amelard, Robert; Scharfenberger, Christian; Wong, Alexander; Clausi, David A.

    2015-03-01

    Melanin is a pigment that is highly absorptive in the UV and visible electromagnetic spectra. It is responsible for perceived skin tone, and protects against harmful UV effects. Abnormal melanin distribution is often an indicator for melanoma. We propose a novel approach for non-contact melanin distribution via multispectral temporal illumination coding to estimate the two-dimensional melanin distribution based on its absorptive characteristics. In the proposed system, a novel multispectral, cross-polarized, temporally-coded illumination sequence is synchronized with a camera to measure reflectance under both multispectral and ambient illumination. This allows us to eliminate the ambient illumination contribution from the acquired reflectance measurements, and also to determine the melanin distribution in an observed region based on the spectral properties of melanin using the Beer-Lambert law. Using this information, melanin distribution maps can be generated for objective, quantitative assessment of skin type of individuals. We show that the melanin distribution map correctly identifies areas with high melanin densities (e.g., nevi).

  10. Applying photoacoustics to quantification of melanin concentration in retinal pigment epithelium (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Shu, Xiao; Zhang, Hao F.; Liu, Wenzhong

    2016-03-01

    The melanin in the retinal pigment epithelium (RPE) protects retina and other ocular tissues by photo-screening and acting as antioxidant and free radical scavenger. It helps maintain normal visual functions since human eye is subjected to lifelong high oxygen stress and photon exposure. Loss of the RPE melanin weakens the protection mechanism and jeopardizes ocular health. Local decrease in the RPE melanin concentration is believed to be both a cause and a sign of early-stage age-related macular degeneration (AMD), the leading blinding disease in developed world. Current technology cannot quantitatively measure the RPE melanin concentration which might be a promising marker in early AMD screening. Photoacoustic ophthalmoscopy (PAOM), as an emerging optical absorption-based imaging technology, can potentially be applied to measure the RPE melanin concentration if the dependence of the detectable photoacoustic (PA) signal amplitudes on the RPE melanin concentrations is verified. In this study, we tested the feasibility of using PA signal ratio from RPE melanin and the nearby retinal blood vessels as an indicator of the RPE melanin variation. A novel whole eye optical model was designed and Monte Carlo modeling of light (MCML) was employed. We examined the influences on quantification from PAOM axial resolution, the depth and diameter of the retinal blood vessel, and the RPE thickness. The results show that the scheme is robust to individual histological and illumination variations. This study suggests that PAOM is capable of quantitatively measuring the RPE melanin concentration in vivo.

  11. Structural Characterization of Melanin Pigments from Commercial Preparations of the Edible Mushroom Auricularia auricula

    PubMed Central

    Prados-Rosales, Rafael; Toriola, Stacy; Nakouzi, Antonio; Chatterjee, Subhasish; Stark, Ruth; Gerfen, Gary; Tumpowsky, Paul; Dadachova, Ekaterina; Casadevall, Arturo

    2016-01-01

    Many of the most widely consumed edible mushrooms are pigmented, and these have been associated with some beneficial health effects. Nevertheless, the majority of the reported compounds associated with these desirable properties are non-pigmented. We have previously reported that melanin pigment from the edible mushroom Auricularia auricula can protect mice against ionizing radiation, although no physicochemical characterization was reported. Consequently, in this study we have characterized commercial A. auricula mushroom preparations for melanin content and carried out structural characterization of isolated insoluble melanin materials using a panel of sophisticated spectroscopic and physical/imaging techniques. Our results show that approximately 10% of the dry mass of A. auricula is melanin and that the pigment has physicochemical properties consistent with those of eumelanins, including hosting a stable free radical population. Electron microscopy studies show that melanin is associated with the mushroom cell wall in a manner similar to that of melanin from the model fungus C. neoformans. Elemental analysis of melanin indicated C, H, and N ratios consistent with 5,6-dihydroxyindole-2-carboxylic acid/5,6-dihydroxyindole and 1,8-dihydroxynaphthalene eumelanin. Validation of the identity of the isolated product as melanin was achieved by EPR analysis. A. auricula melanin manifested structural differences, relative to the C. neoformans melanin, with regard to the variable proportions of alkyl chains or oxygenated carbons. Given the necessity for new oral and inexpensive radioprotective materials coupled with the commercial availability of A. auricula mushrooms, this product may represent an excellent source of edible melanin. PMID:26244793

  12. Melanin, a promising radioprotector: Mechanisms of actions in a mice model

    SciTech Connect

    Kunwar, A.; Adhikary, B.; Jayakumar, S.; Barik, A.; Chattopadhyay, S.; Raghukumar, S.; Priyadarsini, K.I.

    2012-10-15

    The radioprotective effect of extracellular melanin, a naturally occurring pigment, isolated from the fungus Gliocephalotrichum simplex was examined in BALB/C mice, and the probable mechanism of action was established. At an effective dose of 50 mg/kg body weight, melanin exhibited both prophylactic and mitigative activities, increasing the 30-day survival of mice by 100% and 60%, respectively, after exposure to radiation (7 Gy, whole body irradiation (WBI)). The protective activity of melanin was primarily due to inhibition of radiation-induced hematopoietic damages as evidenced by improvement in spleen parameters such as index, total cellularity, endogenous colony forming units, and maintenance of circulatory white blood cells and platelet counts. Melanin also reversed the radiation-induced decrease in ERK phosphorylation in splenic tissue, which may be the key feature in its radioprotective action. Additionally, our results indicated that the sustained activation of AKT, JNK and P38 proteins in splenic tissue of melanin pre-treated group may also play a secondary role. This was also supported by the fact that melanin could prevent apoptosis in splenic tissue by decreasing BAX/Bcl-XL ratio, and increasing the expressions of the proliferation markers (PCNA and Cyclin D1), compared to the radiation control group. Melanin also reduced the oxidative stress in hepatic tissue and abrogated immune imbalance by reducing the production of pro-inflammatory cytokines (IL6 and TNFα). In conclusion, our results confirmed that fungal melanin is a very effective radioprotector against WBI and the probable mechanisms of radioprotection are due to modulation in pro-survival (ERK) signaling, prevention of oxidative stress and immunomodulation. -- Highlights: ► Melanin showed promising radioprotection under pre and post irradiation condition. ► Melanin protects the hematopoietic system from radiation induced damage. ► Melanin modulates pro-survival pathways, immune system

  13. The Effect of Retinal Melanin on Optical Coherence Tomography Images

    PubMed Central

    Wilk, Melissa A.; Huckenpahler, Alison L.; Collery, Ross F.; Link, Brian A.; Carroll, Joseph

    2017-01-01

    Purpose We assessed the effect of melanin on the appearance of hyperreflective outer retinal bands in optical coherence tomography (OCT) images. Methods A total of 23 normal subjects and 51 patients with albinism were imaged using the Bioptigen high-resolution spectral-domain OCT. In addition, three wild type, three albino (slc45a2b4/b4), and eight tyrosinase mosaic zebrafish were imaged with the hand-held Bioptigen Envisu R2200 OCT. To identify pigmented versus nonpigmented regions in the tyrosinase mosaic zebrafish, en face summed volume projections of the retinal pigment epithelium (RPE) were created from volume scans. Longitudinal reflectivity profiles were generated from B-scans to assess the width and maximum intensity of the RPE band in fish, or the presence of one or two RPE/Bruch's membrane (BrM) bands in humans. Results The foveal RPE/BrM appeared as two bands in 71% of locations in patients with albinism and 45% of locations in normal subjects (P = 0.0003). Pigmented zebrafish retinas had significantly greater RPE reflectance, and pigmented regions of mosaic zebrafish also had significantly broader RPE bands than all other groups. Conclusions The hyperreflective outer retinal bands in OCT images are highly variable in appearance. We showed that melanin is a major contributor to the intensity and width of the RPE band on OCT. One should use caution in extrapolating findings from OCT images of one or even a few individuals to define the absolute anatomic correlates of the hyperreflective outer retinal bands in OCT images. Translational Relevance Melanin affects the appearance of the outer retinal bands in OCT images. Use of animal models may help dissect the anatomic correlates of the complex reflective signals in OCT retinal images. PMID:28392975

  14. Complexation in two-component chlortetracycline-melanin solutions

    NASA Astrophysics Data System (ADS)

    Lapina, V. A.; Pershukevich, P. P.; Dontsov, A. E.; Bel'Kov, M. V.

    2008-01-01

    The spectra and kinetics of fluorescence of two-component solutions of the chlortetracycline (CHTC)-DOPA-melanin (melanin or ME) system in water have been investigated. The data obtained have been compared to similar data for solutions of CHTC-melanosome from bull eye (MB), which contains natural melanin, in K-phosphate buffer at pH 7.4. The overall results indicate the occurrence of complexation between molecules of CHTC and ME as they are being excited. The studies of complexation in the solution of CHTC-MB in the buffer are complicated by the formation of a CHTC-buffer complex. The effect of optical radiation in the range 330-750 nm on the CHTC-ME complex shows selectivity: the greatest change in the spectrum occurs when the wavelength of the exciting radiation coincides with the long-wavelength band maximum of the fluorescence excitation spectrum of the CHTC-ME complex in aqueous solution. In this range, CHTC and especially ME show high photochemical stability. The nature of the radiation effect on the studied compounds in the hard UV range (λ < 330 nm) differs greatly from that in the range 330-750 nm. It is apparently accompanied by significant photochemical transmutations of all system components. By comparing the characteristics of the CHTC-ME systems with those of the related drug doxycycline (DC-ME), the conclusion has been made that the chlorine atom plays a vital role in formation of the short-wavelength band in the fluorescence spectrum of the CHTC-ME complex.

  15. Odontogenic Cyst with Verrucous Proliferation Exhibiting Melanin Pigmentation

    PubMed Central

    Soni, Krupa Mehta; Ahmed, Junaid; Bhat, Keshava; Kottieth Pallam, Nandita; Lewis, Amitha Juanita

    2017-01-01

    Verrucous proliferation arising from odontogenic cysts is a rare entity. We report an unusual case of an infected odontogenic cyst with verrucous proliferation and melanin pigmentation in a 13-year-old male patient who presented with an intraoral swelling in relation to impacted teeth 26 and 27. The enucleated lesion was diagnosed as an odontogenic keratocyst and the patient died within two years of presentation due to multiple recurrences. The clinical, radiological, and microscopic features of the lesion are presented with an attempt to discuss the etiopathogenesis. The case hereby reported is uncommon with only eight cases reported in the literature. PMID:28409045

  16. Induced melanin reduces mutations and cell killing in mouse melanoma.

    PubMed

    Li, W; Hill, H Z

    1997-03-01

    When melanin absorbs light energy, it can produce potentially damaging active oxygen species. There is little doubt that constitutive pigment in dark-skinned individuals is photoprotective against skin cancer, but induced pigment-as in tanning-may not be. The first step in cancer induction is mutation in DNA. The most suitable systems for evaluating the role of melanin are those in which pigment can be varied and mutations can be measured. Several cell lines from Cloudman S91 mouse melanoma can be induced to form large quantities of melanin pigment after treatment with a number of different agents enabling comparison of mutant yields in the same cells differing principally in pigment concentration. In these studies, melanin was induced with synthetic alpha-melanocyte-stimulating hormone and with isobutyl methyl xanthine in the cell line S91/mel. The former inducer produced about 50% more pigment than the latter. Survival and mutation induction at the Na+/K(+)-ATPase locus were studied using ethyl methane sulfonate (EMS), a standard mutagen and five UV lamps emitting near monochromatic and polychromatic UV light in the three wave-length ranges of UV. There was greater protection against killing and mutation induction in the more heavily pigmented cells after exposure to EMS and after irradiation with monochromatic UVC and UVB. There was significant protection against killing by polychromatic UVB + UVA (FS20), but the small degree of protection against mutation was not significant. No significant change in killing and mutation using the same protocol was seen in S91/amel, a related cell line that does not respond to these inducers. No mutants were produced by either monochromatic or polychromatic UVA at doses that killed 50% of the cells. Our results show that induced pigment-shown earlier to be eumelanin (K. A. Cieszka et al., Exp. Dermatol. 4, 192-198, 1995)-is photo- and chemoprotective, but it is less effective in protection against mutagenesis by polychromatic

  17. Melanins Protect Sporothrix brasiliensis and Sporothrix schenckii from the Antifungal Effects of Terbinafine

    PubMed Central

    Almeida-Paes, Rodrigo; Figueiredo-Carvalho, Maria Helena Galdino; Brito-Santos, Fábio; Almeida-Silva, Fernando; Oliveira, Manoel Marques Evangelista; Zancopé-Oliveira, Rosely Maria

    2016-01-01

    Terbinafine is a recommended therapeutic alternative for patients with sporotrichosis who cannot use itraconazole due to drug interactions or side effects. Melanins are involved in resistance to antifungal drugs and Sporothrix species produce three different types of melanin. Therefore, in this study we evaluated whether Sporothrix melanins impact the efficacy of antifungal drugs. Minimal inhibitory concentrations (MIC) and minimal fungicidal concentrations (MFC) of two Sporothrix brasiliensis and four Sporothrix schenckii strains grown in the presence of the melanin precursors L-DOPA and L-tyrosine were similar to the MIC determined by the CLSI standard protocol for S. schenckii susceptibility to amphotericin B, ketoconazole, itraconazole or terbinafine. When MICs were determined in the presence of inhibitors to three pathways of melanin synthesis, we observed, in four strains, an increase in terbinafine susceptibility in the presence of tricyclazole, a DHN-melanin inhibitor. In addition, one S. schenckii strain grown in the presence of L-DOPA had a higher MFC value when compared to the control. Growth curves in presence of 2×MIC concentrations of terbinafine showed that pyomelanin and, to a lesser extent, eumelanin were able to protect the fungi against the fungicidal effect of this antifungal drug. Our results suggest that melanin protects the major pathogenic species of the Sporothrix complex from the effects of terbinafine and that the development of new antifungal drugs targeting melanin synthesis may improve sporotrichosis therapies. PMID:27031728

  18. Melanins Protect Sporothrix brasiliensis and Sporothrix schenckii from the Antifungal Effects of Terbinafine.

    PubMed

    Almeida-Paes, Rodrigo; Figueiredo-Carvalho, Maria Helena Galdino; Brito-Santos, Fábio; Almeida-Silva, Fernando; Oliveira, Manoel Marques Evangelista; Zancopé-Oliveira, Rosely Maria

    2016-01-01

    Terbinafine is a recommended therapeutic alternative for patients with sporotrichosis who cannot use itraconazole due to drug interactions or side effects. Melanins are involved in resistance to antifungal drugs and Sporothrix species produce three different types of melanin. Therefore, in this study we evaluated whether Sporothrix melanins impact the efficacy of antifungal drugs. Minimal inhibitory concentrations (MIC) and minimal fungicidal concentrations (MFC) of two Sporothrix brasiliensis and four Sporothrix schenckii strains grown in the presence of the melanin precursors L-DOPA and L-tyrosine were similar to the MIC determined by the CLSI standard protocol for S. schenckii susceptibility to amphotericin B, ketoconazole, itraconazole or terbinafine. When MICs were determined in the presence of inhibitors to three pathways of melanin synthesis, we observed, in four strains, an increase in terbinafine susceptibility in the presence of tricyclazole, a DHN-melanin inhibitor. In addition, one S. schenckii strain grown in the presence of L-DOPA had a higher MFC value when compared to the control. Growth curves in presence of 2×MIC concentrations of terbinafine showed that pyomelanin and, to a lesser extent, eumelanin were able to protect the fungi against the fungicidal effect of this antifungal drug. Our results suggest that melanin protects the major pathogenic species of the Sporothrix complex from the effects of terbinafine and that the development of new antifungal drugs targeting melanin synthesis may improve sporotrichosis therapies.

  19. Monte Carlo investigation on quantifying the retinal pigment epithelium melanin concentration by photoacoustic ophthalmoscopy.

    PubMed

    Shu, Xiao; Liu, Wenzhong; Zhang, Hao F

    2015-10-01

    The retinal pigment epithelium (RPE) melanin plays an important role in maintaining normal visual functions. A decrease in the RPE melanin concentration with aging is believed to be associated with several blinding diseases, including age-related macular degeneration. Quantifying the RPE melanin noninvasively is therefore important in evaluating the retinal health and aging conditions. Photoacoustic ophthalmoscopy (PAOM), as an optical absorption-based imaging technology, can potentially be applied to measure variations in the RPE melanin if the relationship between the detected photoacoustic (PA) signal amplitudes and the RPE melanin concentrations can be established. In this work, we tested the feasibility of using PA signals from retinal blood vessels as references to measure RPE melanin variation using Monte Carlo (MC) simulation. The influences from PAOM axial resolution, the depth and diameter of the retinal blood vessel, and the RPE thickness were examined. We proposed a calibration scheme by relating detected PA signals to the RPE melanin concentrations, and we found that the scheme is robust to these tested parameters. This study suggests that PAOM has the capability of quantitatively measuring the RPE melanin in vivo.

  20. Color reduction of melanin by lysosomal and peroxisomal enzymes isolated from mammalian cells.

    PubMed

    Park, Dong Jun; Sekhon, Simranjeet Singh; Yoon, Jihee; Kim, Yang-Hoon; Min, Jiho

    2016-02-01

    Lysosomes and peroxisomes are organelles with many functions in all eukaryotic cells. Lysosomes contain hydrolytic enzymes (lysozyme) that degrade molecules, whereas peroxisomes contain enzymes such as catalase that convert hydrogen peroxide (H2O2) to water and oxygen and neutralize toxicity. In contrast, melanin is known as a helpful element to protect the skin against harmful ultraviolet rays. However, a high quantity of melanin leads to hyperpigmentation or skin cancer in human. New materials have already been discovered to inhibit tyrosinase in melanogenesis; however, melanin reduction does not suggest their preparation. In this study, we report that the color intensity because of melanin decreased by the cellular activation of lysosomes and peroxisomes. An increase in the superficial intensity of lysosome and peroxisome activities of HeLa cells was observed. In addition, a decrease in the amount of melanin has also been observed in mammalian cells without using any other chemical, showing that the process can work in vivo for treating melanin. Therefore, the results of this study indicate that the amount of melanin decreases by the lysosome and peroxisome activity after entering the cells, and functional organelles are effective in color reduction. This mechanism can be used in vivo for treating melanin.

  1. Continuous microwave saturation of EPR spectra of melanin complexes at different temperatures

    NASA Astrophysics Data System (ADS)

    Zdybel, Magdalena; Pilawa, Barbara; Buszman, Ewa; Wrzesniok, Dorota; Krzyminiewski, Ryszard; Kruczynski, Zdzislaw

    2011-01-01

    Paramagnetic centers in DOPA-melanin and complexes of DOPA-melanin with netilmicin and Cu(II) were studied by the use of an X-band (9.3 GHz) electron paramagnetic resonance (EPR) spectroscopy. Measurements of continuous microwave saturation of EPR spectra at temperatures: 125 K, 175 K, 225 K, 275 K, were performed. Homogeneous broadening of all the examined EPR spectra was observed. EPR spectra of DOPA-melanin-Cu(II) complexes saturated at higher microwave powers than the others tested melanin samples. Fast spin-lattice relaxation exists in DOPA-melanin-Cu(II) complexes. Slow spin-lattice relaxation processes exist in melanin's paramagnetic centers of DOPA-melanin and its complexes with netilmicin, and its complexes with both netilimicin and Cu(II). EPR spectra of all the tested samples saturated at higher microwave powers with increasing of the measuring temperature. Faster spin-lattice relaxation processes occurs in DOPA-melanin and its complexes with netilmicin and Cu(II) at higher temperature.

  2. Synthesis of melanin pigment by Candida albicans in vitro and during infection.

    PubMed

    Morris-Jones, Rachael; Gomez, Beatriz L; Diez, Soraya; Uran, Martha; Morris-Jones, Stephen D; Casadevall, Arturo; Nosanchuk, Joshua D; Hamilton, Andrew J

    2005-09-01

    Melanins are implicated in the pathogenesis of several important human diseases. This study confirmed the presence of melanin particles in Candida albicans in vitro and during infection. Dark particles were isolated from the digestion of C. albicans cultures and from infected tissue, as established by electron microscopy and immunofluorescence techniques.

  3. Synthesis of Melanin Pigment by Candida albicans In Vitro and during Infection

    PubMed Central

    Morris-Jones, Rachael; Gomez, Beatriz L.; Diez, Soraya; Uran, Martha; Morris-Jones, Stephen D.; Casadevall, Arturo; Nosanchuk, Joshua D.; Hamilton, Andrew J.

    2005-01-01

    Melanins are implicated in the pathogenesis of several important human diseases. This study confirmed the presence of melanin particles in Candida albicans in vitro and during infection. Dark particles were isolated from the digestion of C. albicans cultures and from infected tissue, as established by electron microscopy and immunofluorescence techniques. PMID:16113337

  4. Gingival melanin depigmentation by Er:YAG laser: a literature review.

    PubMed

    Pavlic, Verica; Brkic, Zlata; Marin, Sasa; Cicmil, Smiljka; Gojkov-Vukelic, Mirjana; Aoki, Akira

    2017-10-06

    Laser ablation is recently suggested as a most effective and reliable technique for depigmentation of melanin hyperpigmented gingiva. To date, different lasers have been used for gingival depigmentation (CO2, diode, Nd:YAG, Er:YAG and Er,Cr:YSGG lasers). The use of Er:YAG laser for depigmentation of melanin hyperpigmented gingiva has gained increasing importance in recent years. The purpose of this study was to report removal of gingival melanin pigmentation using an Er:YAG laser in a literature review. The main outcomes, such as improvement of signs (clinical parameters of bleeding, erythema, swelling and wound healing), symptoms (pain) and melanin recurrence/repigmentation were measured. The literature demonstrated that depigmentation of gingival melanin pigmentation can be performed safely and effectively by Er:YAG laser resulting in healing and an esthetically significant improvement of gingival discoloration. Thus, Er:YAG laser seems to be safe and useful in melanin depigmentation procedure. However, the main issue in giving the final conclusion of the optimal Er:YAG laser use in melanin depigmentation is that, to date, studies are offering completely discrepant Er:YAG laser procedure protocols (complex settings of laser parameters), and different criteria for the assessment of depigmentation and repigmentation (recurrence), thus hampering the comparison of the results. Therefore, further studies are necessary to give an optimal recommendation on the use of Er:YAG laser in gingival melanin hyperpigmentation.

  5. Melanin-based plumage coloration in the house finch is unaffected by coccidial infection

    PubMed Central

    Hill, G. E.; Brawner, W. R.

    1998-01-01

    For most species of birds, ornamental plumage coloration may result from two types of pigments: carotenoids and melanins. Despite the fact that melanin pigments can be synthesized by birds from basic, amino acid precursors, while carotenoids cannot be synthesized by birds and must be ingested, melanin-based plumage coloration and carotenoid-based plumage coloration have often been treated as a single trait in investigations of the function and evolution of plumage coloration. Expression of carotenoid-based coloration is known to be dependent on condition, while the effects of individual condition have not been well-tested for expression of melanin-based coloration. In this study, we experimentally tested the effect of coccidial infection of the intestinal tract of male house finches during moult on expression of melanin-based plumage coloration. Coccidial infection had a significant negative effect on carotenoid-based coloration, but it had no significant effect on melanin-based feather coloration. Unlike carotenoid-based coloration, melanin-based coloration may be cheap to produce, and honesty of melanin-based coloration my require social mediation.

  6. Melanostatin, a new melanin synthesis inhibitor. Production, isolation, chemical properties, structure and biological activity.

    PubMed

    Ishihara, Y; Oka, M; Tsunakawa, M; Tomita, K; Hatori, M; Yamamoto, H; Kamei, H; Miyaki, T; Konishi, M; Oki, T

    1991-01-01

    Melanostatin, a new antibiotic with melanin synthesis inhibitor activity, was isolated from the fermentation broth of Streptomyces clavifer No. N924-2. Its structure was determined by spectral analysis and degradation experiments. Melanostatin strongly inhibited melanin formation in Streptomyces bikiniensis NRRL B-1049 and B16 melanoma cells.

  7. Bio-inspired Structural Colors from Deposition of Synthetic Melanin Nanoparticles by Evaporative Self-assembly

    NASA Astrophysics Data System (ADS)

    Xiao, Ming; Li, Yiwen; Deheyn, Dimitri; Yue, Xiujun; Gianneschi, Nathan; Shawkey, Matthew; Dhinojwala, Ali

    2015-03-01

    Melanin, a ubiquitous black or brown pigment in the animal kingdom, is a unique but poorly understood biomaterial. Many bird feathers contain melanosomes (melanin-containing organelles), which pack into ordered nanostructures, like multilayer or two-dimensional photonic crystal structures, to produce structural colors. To understand the optical properties of melanin and how melanosomes assemble into certain structures to produce colors, we prepared synthetic melanin (polydopamine) particles with variable sizes and aspect ratios. We have characterized the absorption and refractive index of the synthetic melanin particles. We have also shown that we can use an evaporative process to self-assemble melanin films with a wide range of colors. The colors obtained using this technique is modeled using a thin-film interference model and the optical properties of the synthetic melanin nanoparticles. Our results on self-assembly of synthetic melanin nanoparticles provide an explanation as why the use of melanosomes to produce colors is prevalent in the animal kingdom. National science foundation, air force office of scientific research, human frontier science program.

  8. Interactions between Melanin Enzymes and Their Atypical Recruitment to the Secretory Pathway by Palmitoylation

    PubMed Central

    Upadhyay, Srijana; Xu, Xinping

    2016-01-01

    ABSTRACT Melanins are biopolymers that confer coloration and protection to the host organism against biotic or abiotic insults. The level of protection offered by melanin depends on its biosynthesis and its subcellular localization. Previously, we discovered that Aspergillus fumigatus compartmentalizes melanization in endosomes by recruiting all melanin enzymes to the secretory pathway. Surprisingly, although two laccases involved in the late steps of melanization are conventional secretory proteins, the four enzymes involved in the early steps of melanization lack a signal peptide or a transmembrane domain and are thus considered “atypical” secretory proteins. In this work, we found interactions among melanin enzymes and all melanin enzymes formed protein complexes. Surprisingly, the formation of protein complexes by melanin enzymes was not critical for their trafficking to the endosomal system. By palmitoylation profiling and biochemical analyses, we discovered that all four early melanin enzymes were strongly palmitoylated during conidiation. However, only the polyketide synthase (PKS) Alb1 was strongly palmitoylated during both vegetative hyphal growth and conidiation when constitutively expressed alone. This posttranslational lipid modification correlates the endosomal localization of all early melanin enzymes. Intriguingly, bioinformatic analyses predict that palmitoylation is a common mechanism for potential membrane association of polyketide synthases (PKSs) and nonribosomal peptide synthetases (NRPSs) in A. fumigatus. Our findings indicate that protein-protein interactions facilitate melanization by metabolic channeling, while posttranslational lipid modifications help recruit the atypical enzymes to the secretory pathway, which is critical for compartmentalization of secondary metabolism. PMID:27879337

  9. Monte Carlo investigation on quantifying the retinal pigment epithelium melanin concentration by photoacoustic ophthalmoscopy

    NASA Astrophysics Data System (ADS)

    Shu, Xiao; Liu, Wenzhong; Zhang, Hao F.

    2015-10-01

    The retinal pigment epithelium (RPE) melanin plays an important role in maintaining normal visual functions. A decrease in the RPE melanin concentration with aging is believed to be associated with several blinding diseases, including age-related macular degeneration. Quantifying the RPE melanin noninvasively is therefore important in evaluating the retinal health and aging conditions. Photoacoustic ophthalmoscopy (PAOM), as an optical absorption-based imaging technology, can potentially be applied to measure variations in the RPE melanin if the relationship between the detected photoacoustic (PA) signal amplitudes and the RPE melanin concentrations can be established. In this work, we tested the feasibility of using PA signals from retinal blood vessels as references to measure RPE melanin variation using Monte Carlo (MC) simulation. The influences from PAOM axial resolution, the depth and diameter of the retinal blood vessel, and the RPE thickness were examined. We proposed a calibration scheme by relating detected PA signals to the RPE melanin concentrations, and we found that the scheme is robust to these tested parameters. This study suggests that PAOM has the capability of quantitatively measuring the RPE melanin in vivo.

  10. Monte Carlo investigation on quantifying the retinal pigment epithelium melanin concentration by photoacoustic ophthalmoscopy

    PubMed Central

    Shu, Xiao; Liu, Wenzhong; Zhang, Hao F.

    2015-01-01

    Abstract. The retinal pigment epithelium (RPE) melanin plays an important role in maintaining normal visual functions. A decrease in the RPE melanin concentration with aging is believed to be associated with several blinding diseases, including age-related macular degeneration. Quantifying the RPE melanin noninvasively is therefore important in evaluating the retinal health and aging conditions. Photoacoustic ophthalmoscopy (PAOM), as an optical absorption-based imaging technology, can potentially be applied to measure variations in the RPE melanin if the relationship between the detected photoacoustic (PA) signal amplitudes and the RPE melanin concentrations can be established. In this work, we tested the feasibility of using PA signals from retinal blood vessels as references to measure RPE melanin variation using Monte Carlo (MC) simulation. The influences from PAOM axial resolution, the depth and diameter of the retinal blood vessel, and the RPE thickness were examined. We proposed a calibration scheme by relating detected PA signals to the RPE melanin concentrations, and we found that the scheme is robust to these tested parameters. This study suggests that PAOM has the capability of quantitatively measuring the RPE melanin in vivo. PMID:26469564

  11. EFFECT OF CADMIUM(II) ON FREE RADICALS IN DOPA-MELANIN TESTED BY EPR SPECTROSCOPY.

    PubMed

    Zdybel, Magdalena; Pilawa, Barbara; Chodurek, Ewa

    2015-01-01

    Electron paramagnetic resonance (EPR) spectroscopy may be applied to examine interactions of melanin with metal ions and drugs. In this work EPR method was used to examination of changes in free radical system of DOPA-melanin--the model eumelanin after complexing with diamagnetic cadmium(II) ions. Cadmium(II) may affect free radicals in melanin and drugs binding by this polymer, so the knowledge of modification of properties and free radical concentration in melanin is important to pharmacy. The effect of cadmium(II) in different concentrations on free radicals in DOPA-melanin was determined. EPR spectra of DOPA-melanin, and DOPA-melanin complexes with cadmium(II) were measured by an X-band (9.3 GHz) EPR spectrometer produced by Radiopan (Poznań, Poland) and the Rapid Scan Unit from Jagmar (Krak6w, Poland). The DOPA (3,4-dihydroxyphenylalanine) to metal ions molar ratios in the reaction mixtures were 2:1, 1:1, and 1: 2. High concentrations of o-semiquinone (g ~2.0040) free radicals (~10(21)-10(22) spin/g) characterize DOPA-melanin and its complexes with cadmium(II). Formation of melanin complexes with cadmium(II) increase free radical concentration in DOPA-melanin. The highest free radical concentration was obtained for DOPA-melanin-cadmium(II) (1:1) complexes. Broad EPR lines with linewidths: 0.37-0.73 mT, were measured. Linewidths increase after binding of cadmium(II) to melanin. Changes of integral intensities and linewidths with increasing microwave power indicate the homogeneous broadening of EPR lines, independently on the metal ion concentration. Slow spin-lattice relaxation processes existed in all the tested samples, their EPR lines saturated at low microwave powers. Cadmium(II) causes fastening of spin-lattice relaxation processes in DOPA-melanin. The EPR results bring to light the effect of cadmium(II) on free radicals in melanin, and probably as the consequence on drug binding to eumelanin.

  12. Inhibition of melanin content by Punicalagins in the super fruit pomegranate (Punica granatum).

    PubMed

    Rana, Jatinder; Diwakar, Ganesh; Saito, Lisa; Scholten, Jeffrey D; Mulder, Timothy

    2013-01-01

    Current efforts to develop effective skin lightening products through the inhibition of melanin production have focused on compounds that inhibit the function and activity of tyrosinase, the rate-limiting enzyme in the melanin biosynthesis pathway. Synthetic tyrosinase inhibitors, such as hydroquinone, kojic acid, and arbutin, have been reported to cause skin irritation or acute dermatitis, raising concerns about the safety of these compounds. As a result, there is a need for safe natural ingredients that show effective skin lightening. In this report, we have identified a natural ingredient, pomegranate fruit extract, that inhibits melanin production in melanocytes and shows potential for use as a cosmetic skin lightening agent. In addition, we have identified a polyphenolic compound, punicalagins, as the active melanin inhibitor in pomegranate fruit extract based on its capacity to directly inhibit melanin production.

  13. The nanomechanical role of melanin granules in the retinal pigment epithelium.

    PubMed

    Sarna, Michal; Olchawa, Magdalena; Zadlo, Andrzej; Wnuk, Dawid; Sarna, Tadeusz

    2017-04-01

    Nanomechanical properties of cells and tissues, in particular their elasticity, play an important role in different physiological and pathological processes. Recently, we have demonstrated that melanin granules dramatically modify nanomechanical properties of melanoma cells making them very stiff and, as a result, less aggressive. Although the mechanical effect of melanin granules was demonstrated in pathological cells, it was never studied in the case of normal cells. In this work, we analyzed the impact of melanin granules on nanomechanical properties of primary retinal pigment epithelium tissue fragments isolated from porcine eyes. The obtained results clearly show that melanin granules are responsible for the exceptional nanomechanical properties of the tissue. Our findings suggest that melanin granules in the retinal pigment epithelium may play an important role in sustaining the stiffness of this single cell layer, which functions as a natural mechanical barrier separating the retina from the choroid. Copyright © 2016 Elsevier Inc. All rights reserved.

  14. Melanin targets LC3-associated phagocytosis (LAP): A novel pathogenetic mechanism in fungal disease.

    PubMed

    Chamilos, Georgios; Akoumianaki, Tonia; Kyrmizi, Irene; Brakhage, Axel; Beauvais, Anne; Latge, Jean-Paul

    2016-05-03

    Intracellular swelling of conidia of the major human airborne fungal pathogen Aspergillus fumigatus results in surface exposure of immunostimulatory pathogen-associated molecular patterns (PAMPs) and triggers activation of a specialized autophagy pathway called LC3-associated phagocytosis (LAP) to promote fungal killing. We have recently discovered that, apart from PAMPs exposure, cell wall melanin removal during germination of A. fumigatus is a prerequisite for activation of LAP. Importantly, melanin promotes fungal pathogenicity via targeting LAP, as a melanin-deficient A. fumigatus mutant restores its virulence upon conditional inactivation of Atg5 in hematopoietic cells of mice. Mechanistically, fungal cell wall melanin selectively excludes the CYBA/p22phox subunit of NADPH oxidase from the phagosome to inhibit LAP, without interfering with signaling regulating cytokine responses. Notably, inhibition of LAP is a general property of melanin pigments, a finding with broad physiological implications.

  15. Melanin: dietary mucosal immune modulator from Echinacea and other botanical supplements.

    PubMed

    Pugh, Nirmal D; Balachandran, Premalatha; Lata, Hemant; Dayan, Franck E; Joshi, Vaishali; Bedir, Erdal; Makino, Toshiaki; Moraes, Rita; Khan, Ikhlas; Pasco, David S

    2005-04-01

    The agents responsible for the therapeutic effects of many botanical supplements have not been established in spite of their popularity. Here we show that melanin is a previously unrecognized immunostimulatory compound that is a major component of botanicals traditionally used to enhance immune function. While melanin is present in commonly consumed vegetables, its specific activity is several orders of magnitude less than melanin extracted from these botanicals. The major reason that this agent has eluded detection is its solvent-specific requirement for extraction/solubility. Melanin activates NF-kappa B in monocytes in vitro through a toll-like receptor 2-dependent process. Ingestion of melanin by mice for four days increases production ex vivo of interferon-gamma by spleen cells and IgA and interleukin-6 by Peyer's patch cells. The identification of this new class of mucosal immune stimulants will allow further characterization of botanical products and advances our understanding of the basis for their traditional use.

  16. [Utilization of melanin precursors for experimental chemotherapy of malignant melanoma].

    PubMed

    Jimbow, K; Miura, S; Ito, Y; Kasuga, T; Ito, S

    1984-10-01

    Melanin synthesis is a metabolic pathway unique and specific to melanocytes. It occurs by conversion of tyrosine to dopa and dopaquinone in the presence of tyrosinase. It is highly accelerated in malignant melanoma with a marked increase of tyrosinase activity. This study summarizes the recent progress in experimental chemotherapeutic approaches to malignant melanoma by utilizing melanin precursors, and presents our current results. Our studies indicated (a) that hydroquinone and 4-isopropylcatechol are selectively toxic to melanocytes and melanoma cells, (b) that their actions are mediated through tyrosinase, and (c) that dopa is selectively and highly incorporated into melanoma cells and melanocytes depending on the tyrosinase activity. In addition, our new compounds, i.e., 4-S-cysteinylphenol and 4-S-cysteaminylphenol were highly toxic to melanoma cells, increasing the life span of B16 melanoma bearing mice and decreasing melanoma growth in C57 BL mice. Other synthetic compounds, e.g., cysteinylcatechols and their devivatives, were, however, not toxic to melanoma cells. 4-S-cysteinylphenol and 4-S-cysteaminylphenol appeared to exert their cytotoxicity through the action of tyrosinase present in melanoma cells, thus providing a kind of "guided missile" approach to melanoma chemotherapy.

  17. Melanin pigmentation in mammalian skin and its hormonal regulation.

    PubMed

    Slominski, Andrzej; Tobin, Desmond J; Shibahara, Shigeki; Wortsman, Jacobo

    2004-10-01

    Cutaneous melanin pigment plays a critical role in camouflage, mimicry, social communication, and protection against harmful effects of solar radiation. Melanogenesis is under complex regulatory control by multiple agents interacting via pathways activated by receptor-dependent and -independent mechanisms, in hormonal, auto-, para-, or intracrine fashion. Because of the multidirectional nature and heterogeneous character of the melanogenesis modifying agents, its controlling factors are not organized into simple linear sequences, but they interphase instead in a multidimensional network, with extensive functional overlapping with connections arranged both in series and in parallel. The most important positive regulator of melanogenesis is the MC1 receptor with its ligands melanocortins and ACTH, whereas among the negative regulators agouti protein stands out, determining intensity of melanogenesis and also the type of melanin synthesized. Within the context of the skin as a stress organ, melanogenic activity serves as a unique molecular sensor and transducer of noxious signals and as regulator of local homeostasis. In keeping with these multiple roles, melanogenesis is controlled by a highly structured system, active since early embryogenesis and capable of superselective functional regulation that may reach down to the cellular level represented by single melanocytes. Indeed, the significance of melanogenesis extends beyond the mere assignment of a color trait.

  18. Pigmented basal cell carcinoma: increased melanin or increased melanocytes?

    PubMed

    Brankov, Nikoleta; Prodanovic, Edward M; Hurley, M Yadira

    2016-12-01

    Studies on the precise cause of increased melanization in pigmented basal cell carcinomas (BCC) are limited. We aimed to determine whether the cause of melanization is from increased number of melanocytes or increased melanin pigment, and if there is a difference in the number of melanocytes on different sun-exposed locations. A retrospective review of 45 skin biopsies from January 2011 to February 2011 was performed; 30 were diagnosed as pigmented BCC and 15 as non-pigmented BCC. Immunohistochemistry for MART-1 (melanoma-associated antigen recognized by T-cell 1)/Melan-A (clone M2-7610 + M2-9E3; Leica Microsystems Inc. Buffalo Grove, IL, USA) from Biocare Medical (Concord, CA, USA) was performed on all biopsies. Associations between histopathologic features, number of melanocytes, location, and specific diagnoses were analyzed by Mann-Whitney U test. The mean melanocyte count per high powered field in pigmented BCCs from sun-exposed skin was 101.9 and from intermittently sun-exposed skin was 122.5, as compared to the controls (nodular non-pigmented BCC) of 27.4 (p = 0.002) and 34.9 (p = 0.002), respectively. Pigmented BCCs have a higher mean melanocyte count as compared to non-pigmented BCCs irrespective of location. Therefore, the pigment is not only due to increased melanin, but also due to increased melanocytes. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  19. Quantifying melanin concentration in retinal pigment epithelium using broadband photoacoustic microscopy.

    PubMed

    Shu, Xiao; Li, Hao; Dong, Biqin; Sun, Cheng; Zhang, Hao F

    2017-06-01

    Melanin is the dominant light absorber in retinal pigment epithelium (RPE). The loss of RPE melanin is a sign of ocular senescence and is both a risk factor and a symptom of age-related macular degeneration (AMD). Quantifying the RPE melanin concentration provides insight into the pathological role of RPE in ocular aging and the onset and progression of AMD. The main challenge in accurate quantification of RPE melanin concentration is to distinguish this ten-micrometer-thick cell monolayer from the underlying choroid, which also contains melanin but carries different pathognomonic information. In this work, we investigated a three-dimensional photoacoustic microscopic (PAM) method with high axial resolution, empowered by broad acoustic detection bandwidth, to distinguish RPE from choroid and quantify melanin concentrations in the RPE ex vivo. We first conducted numerical simulation on photoacoustic generation in the RPE, which suggested that a PAM system with at least 100-MHz detection bandwidth provided sufficient axial resolution to distinguish the melanin in RPE from that in choroid. Based on simulation results, we integrated a transparent broadband micro-ring resonator (MRR) based detector in a homebuilt PAM system. We imaged ex vivo RPE-choroid complexes (RCCs) from both porcine and human eyes and quantified the absolute melanin concentrations in the RPE and choroid, respectively. In our study, the measured melanin concentrations were 14.7 mg/mL and 17.0 mg/mL in human and porcine RPE, and 12 mg/mL and 61 mg/mL in human and porcine choroid, respectively. This study suggests that broadband PAM is capable of quantifying the RPE melanin concentration from RCCs ex vivo.

  20. Quantifying melanin concentration in retinal pigment epithelium using broadband photoacoustic microscopy

    PubMed Central

    Shu, Xiao; Li, Hao; Dong, Biqin; Sun, Cheng; Zhang, Hao F.

    2017-01-01

    Melanin is the dominant light absorber in retinal pigment epithelium (RPE). The loss of RPE melanin is a sign of ocular senescence and is both a risk factor and a symptom of age-related macular degeneration (AMD). Quantifying the RPE melanin concentration provides insight into the pathological role of RPE in ocular aging and the onset and progression of AMD. The main challenge in accurate quantification of RPE melanin concentration is to distinguish this ten-micrometer-thick cell monolayer from the underlying choroid, which also contains melanin but carries different pathognomonic information. In this work, we investigated a three-dimensional photoacoustic microscopic (PAM) method with high axial resolution, empowered by broad acoustic detection bandwidth, to distinguish RPE from choroid and quantify melanin concentrations in the RPE ex vivo. We first conducted numerical simulation on photoacoustic generation in the RPE, which suggested that a PAM system with at least 100-MHz detection bandwidth provided sufficient axial resolution to distinguish the melanin in RPE from that in choroid. Based on simulation results, we integrated a transparent broadband micro-ring resonator (MRR) based detector in a homebuilt PAM system. We imaged ex vivo RPE-choroid complexes (RCCs) from both porcine and human eyes and quantified the absolute melanin concentrations in the RPE and choroid, respectively. In our study, the measured melanin concentrations were 14.7 mg/mL and 17.0 mg/mL in human and porcine RPE, and 12 mg/mL and 61 mg/mL in human and porcine choroid, respectively. This study suggests that broadband PAM is capable of quantifying the RPE melanin concentration from RCCs ex vivo. PMID:28663911

  1. Immuno-Histochemical and Quantitative Study of Melanocytes and Melanin Granules in Oral Epithelial Dysplasia.

    PubMed

    Honwad, Swapna; Ravi, S V; Donoghue, Mandana; Joshi, Manjiri

    2017-07-01

    Oral Epithelial dysplasia (OED) is a potentially malignant disorder that is characterized by the presence of architectural and cytological changes. One of the prime factors responsible for the development of these lesions is the usage of tobacco. A variety of factors provide protective mechanism in order to prevent the effects of chemotoxic agents including tobacco products of which, melanin pigmentation is one of the vital elements. Role of melanocytes in progression of OED has remained unclear, so the present study was done to evaluate density of melanocyte and melanin granules in different grades of epithelial dysplasia and to correlate both findings with different grades of epithelial dysplasia. The study included 60 OED cases, of which three histopathogical sections were prepared from each block. The sections were stained with Hematoxylin and Eosin, Masson Fontana and Human Melanoma Black (HMB-45), an immunohistochemical stain. Quantification of melanin granules was evaluated under 40X magnification using arbitrary scale with micrometer square as, 0= Absence of melanin granules, 1= Rare and scattered melanin granules, 2= Dense but not aggregated melanin granules, 3= Dense and aggregated melanin granules. Density of melanocytes was evaluated under 10X magnification. Five consecutive fields were evaluated for melanocytes and melanin granules starting from the field of highest density. There was an insignificant increase in number of melanocytes and melanin granules in mild and moderate dysplasia compared to normal but significant reduction was observed in severe dysplasia. The decrease in number of melanocytes and melanin granules was proportional to severity of epithelial dysplasia. This could be due to chronic irritation by chemical products leading to death of melanocytes.

  2. Physico-Chemical Evaluation of Rationally Designed Melanins as Novel Nature-Inspired Radioprotectors

    PubMed Central

    Schweitzer, Andrew D.; Howell, Robertha C.; Jiang, Zewei; Bryan, Ruth A.; Gerfen, Gary; Chen, Chin-Cheng; Mah, Dennis; Cahill, Sean

    2009-01-01

    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 L-DOPA 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 (2.14·1018, 7.09·1018, and 9.05·1017 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 (137Cs, 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 π-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. PMID:19789711

  3. Multimodal microscopy and the stepwise multi-photon activation fluorescence of melanin

    NASA Astrophysics Data System (ADS)

    Lai, Zhenhua

    The author's work is divided into three aspects: multimodal microscopy, stepwise multi-photon activation fluorescence (SMPAF) of melanin, and customized-profile lenses (CPL) for on-axis laser scanners, which will be introduced respectively. A multimodal microscope provides the ability to image samples with multiple modalities on the same stage, which incorporates the benefits of all modalities. The multimodal microscopes developed in this dissertation are the Keck 3D fusion multimodal microscope 2.0 (3DFM 2.0), upgraded from the old 3DFM with improved performance and flexibility, and the multimodal microscope for targeting small particles (the "Target" system). The control systems developed for both microscopes are low-cost and easy-to-build, with all components off-the-shelf. The control system have not only significantly decreased the complexity and size of the microscope, but also increased the pixel resolution and flexibility. The SMPAF of melanin, activated by a continuous-wave (CW) mode near-infrared (NIR) laser, has potential applications for a low-cost and reliable method of detecting melanin. The photophysics of melanin SMPAF has been studied by theoretical analysis of the excitation process and investigation of the spectra, activation threshold, and photon number absorption of melanin SMPAF. SMPAF images of melanin in mouse hair and skin, mouse melanoma, and human black and white hairs are compared with images taken by conventional multi-photon fluorescence microscopy (MPFM) and confocal reflectance microscopy (CRM). SMPAF images significantly increase specificity and demonstrate the potential to increase sensitivity for melanin detection compared to MPFM images and CRM images. Employing melanin SMPAF imaging to detect melanin inside human skin in vivo has been demonstrated, which proves the effectiveness of melanin detection using SMPAF for medical purposes. Selective melanin ablation with micrometer resolution has been presented using the Target system

  4. Melanin or a Melanin-Like Substance Interacts with the N-Terminal Portion of Prion Protein and Inhibits Abnormal Prion Protein Formation in Prion-Infected Cells.

    PubMed

    Hamanaka, Taichi; Nishizawa, Keiko; Sakasegawa, Yuji; Oguma, Ayumi; Teruya, Kenta; Kurahashi, Hiroshi; Hara, Hideyuki; Sakaguchi, Suehiro; Doh-Ura, Katsumi

    2017-03-15

    Prion diseases are progressive fatal neurodegenerative illnesses caused by the accumulation of transmissible abnormal prion protein (PrP). To find treatments for prion diseases, we searched for substances from natural resources that inhibit abnormal PrP formation in prion-infected cells. We found that high-molecular-weight components from insect cuticle extracts reduced abnormal PrP levels. The chemical nature of these components was consistent with that of melanin. In fact, synthetic melanin produced from tyrosine or 3-hydroxy-l-tyrosine inhibited abnormal PrP formation. Melanin did not modify cellular or cell surface PrP levels, nor did it modify lipid raft or cellular cholesterol levels. Neither did it enhance autophagy or lysosomal function. Melanin was capable of interacting with PrP at two N-terminal domains. Specifically, it strongly interacted with the PrP region of amino acids 23 to 50 including a positively charged amino acid cluster and weakly interacted with the PrP octarepeat peptide region of residues 51 to 90. However, the in vitro and in vivo data were inconsistent with those of prion-infected cells. Abnormal PrP formation in protein misfolding cyclic amplification was not inhibited by melanin. Survival after prion infection was not significantly altered in albino mice or exogenously melanin-injected mice compared with that of control mice. These data suggest that melanin, a main determinant of skin color, is not likely to modify prion disease pathogenesis, even though racial differences in the incidence of human prion diseases have been reported. Thus, the findings identify an interaction between melanin and the N terminus of PrP, but the pathophysiological roles of the PrP-melanin interaction remain unclear.IMPORTANCE The N-terminal region of PrP is reportedly important for neuroprotection, neurotoxicity, and abnormal PrP formation, as this region is bound by many factors, such as metal ions, lipids, nucleic acids, antiprion compounds, and several

  5. Biologically derived melanin electrodes in aqueous sodium-ion energy storage devices.

    PubMed

    Kim, Young Jo; Wu, Wei; Chun, Sang-Eun; Whitacre, Jay F; Bettinger, Christopher J

    2013-12-24

    Biodegradable electronics represents an attractive and emerging paradigm in medical devices by harnessing simultaneous advantages afforded by electronically active systems and obviating issues with chronic implants. Integrating practical energy sources that are compatible with the envisioned operation of transient devices is an unmet challenge for biodegradable electronics. Although high-performance energy storage systems offer a feasible solution, toxic materials and electrolytes present regulatory hurdles for use in temporary medical devices. Aqueous sodium-ion charge storage devices combined with biocompatible electrodes are ideal components to power next-generation biodegradable electronics. Here, we report the use of biologically derived organic electrodes composed of melanin pigments for use in energy storage devices. Melanins of natural (derived from Sepia officinalis) and synthetic origin are evaluated as anode materials in aqueous sodium-ion storage devices. Na(+)-loaded melanin anodes exhibit specific capacities of 30.4 ± 1.6 mAhg(-1). Full cells composed of natural melanin anodes and λ-MnO2 cathodes exhibit an initial potential of 1.03 ± 0.06 V with a maximum specific capacity of 16.1 ± 0.8 mAhg(-1). Natural melanin anodes exhibit higher specific capacities compared with synthetic melanins due to a combination of beneficial chemical, electrical, and physical properties exhibited by the former. Taken together, these results suggest that melanin pigments may serve as a naturally occurring biologically derived charge storage material to power certain types of medical devices.

  6. Syndecan-2 regulates melanin synthesis via protein kinase C βII-mediated tyrosinase activation.

    PubMed

    Jung, Hyejung; Chung, Heesung; Chang, Sung Eun; Choi, Sora; Han, Inn-Oc; Kang, Duk-Hee; Oh, Eok-Soo

    2014-05-01

    Syndecan-2, a transmembrane heparan sulfate proteoglycan that is highly expressed in melanoma cells, regulates melanoma cell functions (e.g. migration). Since melanoma is a malignant tumor of melanocytes, which largely function to synthesize melanin, we investigated the possible involvement of syndecan-2 in melanogenesis. Syndecan-2 expression was increased in human skin melanoma tissues compared with normal skin. In both mouse and human melanoma cells, siRNA-mediated knockdown of syndecan-2 was associated with reduced melanin synthesis, whereas overexpression of syndecan-2 increased melanin synthesis. Similar effects were also detected in human primary epidermal melanocytes. Syndecan-2 expression did not affect the expression of tyrosinase, a key enzyme in melanin synthesis, but instead enhanced the enzymatic activity of tyrosinase by increasing the membrane and melanosome localization of its regulator, protein kinase CβII. Furthermore, UVB caused increased syndecan-2 expression, and this up-regulation of syndecan-2 was required for UVB-induced melanin synthesis. Taken together, these data suggest that syndecan-2 regulates melanin synthesis and could be a potential therapeutic target for treating melanin-associated diseases.

  7. Production of natural melanin by Auricularia auricula and study on its molecular structure.

    PubMed

    Sun, Shujing; Zhang, Xiaojuan; Sun, Shiwei; Zhang, Liaoyuan; Shan, Shukai; Zhu, Hu

    2016-01-01

    In this study, the production and structure of melanin produced by Auricularia auricula have been determined and analyzed in detail. The results showed that the highest mycelial growth rate was observed in low-carbon and carbon-free medium. In low-nitrogen and nitrogen-free medium, melanin yield was very low. Deficiency of tyrosine in medium led to weak secretion of melanin. The inorganic salt could markedly influence mycelia morphology, but did not obviously impact mycelia growth rate and melanin yield. Meanwhile the condensed molecular formula ([C18(OR)3H7O4N2]n) and structural formula of melanin were concluded based on UV-Vis, HPLC, FTIR, NMR and elemental assay. This is an eumelanin and also a macromolecular polymer of 5,6-dihydroxyindole and 5,6-dihydroxyindole-2-carboxylic acid. The 6 main components were phenolic hydroxyl, carboxyl, amidogen, carbonyl, methylene, methyne and sulfur. This work testified that nutritional control was very important to promote melanin production, making melanin more affordable as material in food, cosmetics and medicines.

  8. Stepwise multiphoton activation fluorescence reveals a new method of melanin detection.

    PubMed

    Lai, Zhenhua; Kerimo, Josef; Mega, Yair; Dimarzio, Charles A

    2013-06-01

    The stepwise multiphoton activated fluorescence (SMPAF) of melanin, activated by a continuous-wave mode near infrared (NIR) laser, reveals a broad spectrum extending from the visible spectra to the NIR and has potential application for a low-cost, reliable method of detecting melanin. SMPAF images of melanin in mouse hair and skin are compared with conventional multiphoton fluorescence microscopy and confocal reflectance microscopy (CRM). By combining CRM with SMPAF, we can locate melanin reliably. However, we have the added benefit of eliminating background interference from other components inside mouse hair and skin. The melanin SMPAF signal from the mouse hair is a mixture of a two-photon process and a third-order process. The melanin SMPAF emission spectrum is activated by a 1505.9-nm laser light, and the resulting spectrum has a peak at 960 nm. The discovery of the emission peak may lead to a more energy-efficient method of background-free melanin detection with less photo-bleaching.

  9. The Role of Gingival Melanin Pigmentation in Inflammation of Gingiva, Based on Genetic Analysis

    PubMed Central

    Eid, Hossam A; Syed, Sadatullah; Soliman, Abdel Nasser MM

    2013-01-01

    Background: Aim of the study was to investigate the relationship of melanin pigment and inflammatory process within gingival tissues based on clinical and genetic analysis by differential display technique and DNA sequencing. Materials and Methods: Seventy gingival biopsy specimens were taken from individuals with melanin pigmentation as well as healthy and inflamed gingiva. Specimens were examined by differential display technique using six different arbitrary primers. Cloning, sequencing and sequence analysis for six different genes were performed. Results: Gingival specimens with hyperpigmentation (clinical melanin score = 3) showed presence of both, down- and up-regulatory genes when compared with the gingival specimen with clinical melanin score 0. These genes may have a role in curtailing the progress of gingival inflammation associated with melanin hyperpigmentation. Conclusion: Melanin hyper pigmentation may possess a defensive role against progress of gingival inflammation How to cite this article:Eid HA, Syed S, Soliman AN. The Role of Gingival Melanin Pigmentation in Inflammation of Gingiva, Based on Genetic Analysis. J Int Oral Health 2013; 5(4):1-7. PMID:24155612

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

    NASA Astrophysics Data System (ADS)

    Colleary, Caitlin; Dolocan, Andrei; Gardner, James; Singh, Suresh; Wuttke, Michael; Rabenstein, Renate; Habersetzer, Jörg; Schaal, Stephan; Feseha, Mulugeta; Clemens, Matthew; Jacobs, Bonnie F.; Currano, Ellen D.; Jacobs, Louis L.; Lyng Sylvestersen, Rene; Gabbott, Sarah E.; Vinther, Jakob

    2015-10-01

    In living organisms, color patterns, behavior, and ecology are closely linked. Thus, detection of fossil pigments may permit inferences about important aspects of ancient animal ecology and evolution. Melanin-bearing melanosomes were suggested to preserve as organic residues in exceptionally preserved fossils, retaining distinct morphology that is associated with aspects of original color patterns. Nevertheless, these oblong and spherical structures have also been identified as fossilized bacteria. To date, chemical studies have not directly considered the effects of diagenesis on melanin preservation, and how this may influence its identification. Here we use time-of-flight secondary ion mass spectrometry to identify and chemically characterize melanin in a diverse sample of previously unstudied extant and fossil taxa, including fossils with notably different diagenetic histories and geologic ages. We document signatures consistent with melanin preservation in fossils ranging from feathers, to mammals, to amphibians. Using principal component analyses, we characterize putative mixtures of eumelanin and phaeomelanin in both fossil and extant samples. Surprisingly, both extant and fossil amphibians generally exhibit melanosomes with a mixed eumelanin/phaeomelanin composition rather than pure eumelanin, as assumed previously. We argue that experimental maturation of modern melanin samples replicates diagenetic chemical alteration of melanin observed in fossils. This refutes the hypothesis that such fossil microbodies could be bacteria, and demonstrates that melanin is widely responsible for the organic soft tissue outlines in vertebrates found at exceptional fossil localities, thus allowing for the reconstruction of certain aspects of original pigment patterns.

  11. A Non-canonical Melanin Biosynthesis Pathway Protects Aspergillus terreus Conidia from Environmental Stress.

    PubMed

    Geib, Elena; Gressler, Markus; Viediernikova, Iuliia; Hillmann, Falk; Jacobsen, Ilse D; Nietzsche, Sandor; Hertweck, Christian; Brock, Matthias

    2016-05-19

    Melanins are ubiquitous pigments found in all kingdoms of life. Most organisms use them for protection from environmental stress, although some fungi employ melanins as virulence determinants. The human pathogenic fungus Aspergillus fumigatus and related Ascomycetes produce dihydroxynaphthalene- (DHN) melanin in their spores, the conidia, and use it to inhibit phagolysosome acidification. However, biosynthetic origin of melanin in a related fungus, Aspergillus terreus, has remained a mystery because A. terreus lacks genes for synthesis of DHN-melanin. Here we identify genes coding for an unusual NRPS-like enzyme (MelA) and a tyrosinase (TyrP) that A. terreus expressed under conidiation conditions. We demonstrate that MelA produces aspulvinone E, which is activated for polymerization by TyrP. Functional studies reveal that this new pigment, Asp-melanin, confers resistance against UV light and hampers phagocytosis by soil amoeba. Unexpectedly, Asp-melanin does not inhibit acidification of phagolysosomes, thus likely contributing specifically to survival of A. terreus conidia in acidic environments. Copyright © 2016 Elsevier Ltd. All rights reserved.

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

    PubMed

    Colleary, Caitlin; Dolocan, Andrei; Gardner, James; Singh, Suresh; Wuttke, Michael; Rabenstein, Renate; Habersetzer, Jörg; Schaal, Stephan; Feseha, Mulugeta; Clemens, Matthew; Jacobs, Bonnie F; Currano, Ellen D; Jacobs, Louis L; Sylvestersen, Rene Lyng; Gabbott, Sarah E; Vinther, Jakob

    2015-10-13

    In living organisms, color patterns, behavior, and ecology are closely linked. Thus, detection of fossil pigments may permit inferences about important aspects of ancient animal ecology and evolution. Melanin-bearing melanosomes were suggested to preserve as organic residues in exceptionally preserved fossils, retaining distinct morphology that is associated with aspects of original color patterns. Nevertheless, these oblong and spherical structures have also been identified as fossilized bacteria. To date, chemical studies have not directly considered the effects of diagenesis on melanin preservation, and how this may influence its identification. Here we use time-of-flight secondary ion mass spectrometry to identify and chemically characterize melanin in a diverse sample of previously unstudied extant and fossil taxa, including fossils with notably different diagenetic histories and geologic ages. We document signatures consistent with melanin preservation in fossils ranging from feathers, to mammals, to amphibians. Using principal component analyses, we characterize putative mixtures of eumelanin and phaeomelanin in both fossil and extant samples. Surprisingly, both extant and fossil amphibians generally exhibit melanosomes with a mixed eumelanin/phaeomelanin composition rather than pure eumelanin, as assumed previously. We argue that experimental maturation of modern melanin samples replicates diagenetic chemical alteration of melanin observed in fossils. This refutes the hypothesis that such fossil microbodies could be bacteria, and demonstrates that melanin is widely responsible for the organic soft tissue outlines in vertebrates found at exceptional fossil localities, thus allowing for the reconstruction of certain aspects of original pigment patterns.

  13. Cutaneous melanin exhibiting fluorescence emission under near-infrared light excitation.

    PubMed

    Huang, Zhiwei; Zeng, Haishan; Hamzavi, Iltefat; Alajlan, Abdulmajeed; Tan, Eileen; McLean, David I; Lui, Harvey

    2006-01-01

    Under ultraviolet and visible light excitation, melanin is essentially a nonfluorescent substance. This work reports our study on near-infrared (NIR) fluorescence properties of melanins, and explores potential applications of NIR fluorescence techniques for evaluating skin disorders involving melanin. The NIR fluorescence spectrum is obtained using a fiber optic NIR spectrometer under 785-nm laser excitation. In vitro measurements are performed on synthetic dihydroxyphenylalanine (DOPA) melanin, melanin extracted from Sepia ink sacs, human hair, animal fur, and bird feathers. Paired spectral comparisons of white and black skin appendages show that melanization of hair, fur, or feathers more than doubles the NIR fluorescence. In vivo NIR autofluorescence of normal dorsal and volar forearm skin of 52 volunteers is measured. Dorsal forearm skin, which is darker than volar skin, exhibits significantly greater NIR fluorescence. Patients with vitiligo (n=4), compound nevus (n=3), nevus of Ota (n=1), superficial spreading melanoma (n=3), and postinflammatory hyperpigmentation (n=1) are also evaluated. NIR fluorescence is greater within the lesion than the surrounding normal skin for all these conditions except vitiligo, where the converse was true. The observed melanin NIR fluorescence provides a new approach to in vitro and in vivo melanin detection and quantification that may be particularly useful for evaluating pigmented skin lesions.

  14. Fruit over sunbed: carotenoid skin colouration is found more attractive than melanin colouration.

    PubMed

    Lefevre, Carmen E; Perrett, David I

    2015-01-01

    Skin colouration appears to play a pivotal part in facial attractiveness. Skin yellowness contributes to an attractive appearance and is influenced both by dietary carotenoids and by melanin. While both increased carotenoid colouration and increased melanin colouration enhance apparent health in Caucasian faces by increasing skin yellowness, it remains unclear, firstly, whether both pigments contribute to attractiveness judgements, secondly, whether one pigment is clearly preferred over the other, and thirdly, whether these effects depend on the sex of the face. Here, in three studies, we examine these questions using controlled facial stimuli transformed to be either high or low in (a) carotenoid colouration, or (b) melanin colouration. We show, firstly, that both increased carotenoid colouration and increased melanin colouration are found attractive compared to lower levels of these pigments. Secondly, we show that carotenoid colouration is consistently preferred over melanin colouration when levels of colouration are matched. In addition, we find an effect of the sex of stimuli with stronger preferences for carotenoids over melanin in female compared to male faces, irrespective of the sex of the observer. These results are interpreted as reflecting preferences for sex-typical skin colouration: men have darker skin than women and high melanization in male faces may further enhance this masculine trait, thus carotenoid colouration is not less desirable, but melanin colouration is relatively more desirable in males compared to females. Taken together, our findings provide further support for a carotenoid-linked health-signalling system that is highly important in mate choice.

  15. Biologically derived melanin electrodes in aqueous sodium-ion energy storage devices

    PubMed Central

    Kim, Young Jo; Wu, Wei; Chun, Sang-Eun; Whitacre, Jay F.; Bettinger, Christopher J.

    2013-01-01

    Biodegradable electronics represents an attractive and emerging paradigm in medical devices by harnessing simultaneous advantages afforded by electronically active systems and obviating issues with chronic implants. Integrating practical energy sources that are compatible with the envisioned operation of transient devices is an unmet challenge for biodegradable electronics. Although high-performance energy storage systems offer a feasible solution, toxic materials and electrolytes present regulatory hurdles for use in temporary medical devices. Aqueous sodium-ion charge storage devices combined with biocompatible electrodes are ideal components to power next-generation biodegradable electronics. Here, we report the use of biologically derived organic electrodes composed of melanin pigments for use in energy storage devices. Melanins of natural (derived from Sepia officinalis) and synthetic origin are evaluated as anode materials in aqueous sodium-ion storage devices. Na+-loaded melanin anodes exhibit specific capacities of 30.4 ± 1.6 mAhg−1. Full cells composed of natural melanin anodes and λ-MnO2 cathodes exhibit an initial potential of 1.03 ± 0.06 V with a maximum specific capacity of 16.1 ± 0.8 mAhg−1. Natural melanin anodes exhibit higher specific capacities compared with synthetic melanins due to a combination of beneficial chemical, electrical, and physical properties exhibited by the former. Taken together, these results suggest that melanin pigments may serve as a naturally occurring biologically derived charge storage material to power certain types of medical devices. PMID:24324163

  16. Structural Studies of Bleached Melanin by Synchrotron Small-angle X-ray Scattering¶

    SciTech Connect

    Littrell, Kenneth C.; Gallas, James M.; Zajac, Gerry W.; Thiyagarajan, Pappannan

    2003-01-01

    Small-angle X-ray scattering was used to measure the effects of chemical bleaching on the size and morphology of tyrosine-derived synthetic melanin dispersed in aqueous media. The average size as measured by the radius of gyration of the melanin particles in solution, at neutral to mildly basic pH, decreases from 16.5 to 12.5 angstroms with increased bleaching. The melanin particles exhibit scattering characteristic of sheet-like structures with a thickness of approximately 11 angstroms at all but the highest levels of bleaching. The scattering data are well described by the form factor for scattering from a pancake-like circular cylinder. These data are consistent with the hypothesis that unbleached melanin, at neutral to mildly basic pH, is a planar aggregate of 6- to 10-nm-sized melanin protomolecules, hydrogen bonded through their quinone and phenolic perimeters. The observed decrease in melanin particle size with increased bleaching is interpreted as evidence for deaggregation, most probably the result of oxidative disruption of hydrogen bonds and an increase in the number of charged, carboxylic acid groups, whereby the melanin aggregates disassociate into units composed of decreasing numbers of protomolecules.

  17. Experimental autoimmune anterior uveitis (EAAU): induction by melanin antigen and suppression by various treatments.

    PubMed

    Broekhuyse, R M; Kuhlmann, E D; Winkens, H J

    1993-02-01

    The uveitogenicity of melanin has been a controversial subject for a long time, presumably as a result of the use of ill-defined preparations in the experiments. We have developed procedures for the preparation of purified uveitogenic melanins from the retinal pigment epithelium and choroid that are free from pathogenic retinal photoreceptor proteins. The active melano-antigen is located at the surface of the melanin granules and is probably identical in both tissues. It retains its pathogenicity in hot polar detergent and during in vitro proteolysis, but it is inactivated by macrophage phagocytosis and hydrolysis in hot hydrochloric acid. Lewis rats immunized with microgram doses of bovine retinal pigment epithelial or choroidal melanin develop severe experimental autoimmune anterior uveitis (EAAU) about 10 days later. Retinitis and pinealitis are not observed. Skin melanin prepared in a similar way evokes EAAU as well, but it is only weakly pathogenic. EAAU cannot be transferred by serum, and its development can effectively be inhibited by antibodies to the inciting antigen and by cyclosporin. Vitamin E treatment of the animals causes a delay in its onset. The results indicate that cell-mediated immunity plays a dominant role in the pathogenesis of EAAU. This is the first time it has been shown that purified ocular and skin melanins are able to induce an autoimmune disease. The relevance of this finding for the study of melanin-related immunopathology in man is discussed.

  18. Quantification method for the appearance of melanin pigmentation using independent component analysis

    NASA Astrophysics Data System (ADS)

    Ojima, Nobutoshi; Okiyama, Natsuko; Okaguchi, Saya; Tsumura, Norimichi; Nakaguchi, Toshiya; Hori, Kimihiko; Miyake, Yoichi

    2005-04-01

    In the cosmetics industry, skin color is very important because skin color gives a direct impression of the face. In particular, many people suffer from melanin pigmentation such as liver spots and freckles. However, it is very difficult to evaluate melanin pigmentation using conventional colorimetric values because these values contain information on various skin chromophores simultaneously. Therefore, it is necessary to extract information of the chromophore of individual skins independently as density information. The isolation of the melanin component image based on independent component analysis (ICA) from a single skin image was reported in 2003. However, this technique has not developed a quantification method for melanin pigmentation. This paper introduces a quantification method based on the ICA of a skin color image to isolate melanin pigmentation. The image acquisition system we used consists of commercially available equipment such as digital cameras and lighting sources with polarized light. The images taken were analyzed using ICA to extract the melanin component images, and Laplacian of Gaussian (LOG) filter was applied to extract the pigmented area. As a result, for skin images including those showing melanin pigmentation and acne, the method worked well. Finally, the total amount of extracted area had a strong correspondence to the subjective rating values for the appearance of pigmentation. Further analysis is needed to recognize the appearance of pigmentation concerning the size of the pigmented area and its spatial gradation.

  19. Absorption mechanisms of human melanin in the visible, 400-720 nm.

    PubMed

    Kollias, N; Baqer, A H

    1987-10-01

    In this paper we propose that human melanin absorbs visible radiation through two distinct mechanisms: one that is in effect over the entire visible range and is linear in wavelength, and a second one that is evident at wavelengths in the range 400-500 nm and is exponential in frequency. These mechanisms are apparent in all human diffuse reflectance spectra that we have collected. We show that the absorber is the same in all human volunteer skin samples. By studying the diffuse reflection spectra of DOPA-melanin in solution and DOPA-melanin in powder form, we find that we can correlate the absorption mechanisms, one with melanin in solution (a low molecular weight form) and the other with melanin in powder (a high molecular weight form). Therefore, we propose that melanin exists in two distinct states. This model is of biologic significance, as it provides a reasonable interpretation for the diffuse reflection spectra obtained from delayed pigment (UVB-induced) and immediate pigment (UVA-induced). Delayed pigment appears as an increase of both forms of melanin (neomelanogenesis), whereas immediate pigment appears as an increase in the higher molecular weight form with a commensurate decrease in the lower molecular weight form: the two mechanisms change independently of each other. Finally, we show that we can distinguish spectroscopically between the delayed pigment and the immediate pigment.

  20. Stepwise multiphoton activation fluorescence reveals a new method of melanin detection

    NASA Astrophysics Data System (ADS)

    Lai, Zhenhua; Kerimo, Josef; Mega, Yair; DiMarzio, Charles A.

    2013-06-01

    The stepwise multiphoton activated fluorescence (SMPAF) of melanin, activated by a continuous-wave mode near infrared (NIR) laser, reveals a broad spectrum extending from the visible spectra to the NIR and has potential application for a low-cost, reliable method of detecting melanin. SMPAF images of melanin in mouse hair and skin are compared with conventional multiphoton fluorescence microscopy and confocal reflectance microscopy (CRM). By combining CRM with SMPAF, we can locate melanin reliably. However, we have the added benefit of eliminating background interference from other components inside mouse hair and skin. The melanin SMPAF signal from the mouse hair is a mixture of a two-photon process and a third-order process. The melanin SMPAF emission spectrum is activated by a 1505.9-nm laser light, and the resulting spectrum has a peak at 960 nm. The discovery of the emission peak may lead to a more energy-efficient method of background-free melanin detection with less photo-bleaching.

  1. Geranylgeranylacetone inhibits melanin synthesis via ERK activation in Mel-Ab cells.

    PubMed

    Kim, Eun-Hyun; Jeong, Hyo-Soon; Yun, Hye-Young; Baek, Kwang Jin; Kwon, Nyoun Soo; Park, Kyoung-Chan; Kim, Dong-Seok

    2013-08-14

    Geranylgeranylacetone (GGA) has shown cytoprotective activity through induction of a 70-kDa heat shock protein (HSP70). Although HSP70 is reported to regulate melanogenesis, the effects of GGA on melanin synthesis in melanocytes have not been previously studied. Therefore, this study investigated the effects of GGA on melanogenesis and the related signaling pathways. Melanin content and tyrosinase activities were measured in Mel-Ab cells. GGA-induced signal transduction pathways were investigated by western blot analysis. Our results showed that GGA significantly decreased melanin content in a concentration-dependent manner. Similarly, GGA reduced tyrosinase activity dose-dependently, but it did not directly inhibit tyrosinase. Western blot analysis indicated that GGA downregulated microphthalmia-associated transcription factor (MITF) and tyrosinase protein expression, whereas it increased the phosphorylation of extracellular signal-regulated kinase (ERK) and mammalian target of rapamycin (mTOR). Furthermore, a specific ERK pathway inhibitor, PD98059, blocked GGA-induced melanin reduction and then prevented downregulation of MITF and tyrosinase by GGA. However, a specific mTOR inhibitor, rapamycin, only slightly restored inhibition of melanin production by GGA, indicating that mTOR signaling is not a key mechanism regulating the inhibition of melanin production. These findings suggest that activation of ERK by GGA reduces melanin synthesis in Mel-Ab cells through downregulation of MITF and tyrosinase expression. Copyright © 2013 Elsevier Inc. All rights reserved.

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

    PubMed Central

    Colleary, Caitlin; Dolocan, Andrei; Gardner, James; Singh, Suresh; Wuttke, Michael; Rabenstein, Renate; Habersetzer, Jörg; Schaal, Stephan; Feseha, Mulugeta; Clemens, Matthew; Jacobs, Bonnie F.; Currano, Ellen D.; Jacobs, Louis L.; Sylvestersen, Rene Lyng; Gabbott, Sarah E.; Vinther, Jakob

    2015-01-01

    In living organisms, color patterns, behavior, and ecology are closely linked. Thus, detection of fossil pigments may permit inferences about important aspects of ancient animal ecology and evolution. Melanin-bearing melanosomes were suggested to preserve as organic residues in exceptionally preserved fossils, retaining distinct morphology that is associated with aspects of original color patterns. Nevertheless, these oblong and spherical structures have also been identified as fossilized bacteria. To date, chemical studies have not directly considered the effects of diagenesis on melanin preservation, and how this may influence its identification. Here we use time-of-flight secondary ion mass spectrometry to identify and chemically characterize melanin in a diverse sample of previously unstudied extant and fossil taxa, including fossils with notably different diagenetic histories and geologic ages. We document signatures consistent with melanin preservation in fossils ranging from feathers, to mammals, to amphibians. Using principal component analyses, we characterize putative mixtures of eumelanin and phaeomelanin in both fossil and extant samples. Surprisingly, both extant and fossil amphibians generally exhibit melanosomes with a mixed eumelanin/phaeomelanin composition rather than pure eumelanin, as assumed previously. We argue that experimental maturation of modern melanin samples replicates diagenetic chemical alteration of melanin observed in fossils. This refutes the hypothesis that such fossil microbodies could be bacteria, and demonstrates that melanin is widely responsible for the organic soft tissue outlines in vertebrates found at exceptional fossil localities, thus allowing for the reconstruction of certain aspects of original pigment patterns. PMID:26417094

  3. Chemical characterization of hair melanins in various coat-color mutants of mice.

    PubMed

    Ozeki, H; Ito, S; Wakamatsu, K; Hirobe, T

    1995-09-01

    Mammalian melanins exist in two chemically distinct forms: the brown to black eumelanins and the yellow to reddish pheomelanins. Melanogenesis is influenced by a number of genes, the levels of whose products determine the quantity and quality of the melanins produced. To examine the effects of various coat-color genes on the chemical properties of melanins synthesized in the follicular melanocytes of mice, we have introduced new methods to solubilize differentially pheomelanins and brown-type eumelanins. We applied these and previously developed high-performance liquid chromatography and spectrophotometric methods for assaying eu- and pheomelanins to characterize melanins in various mutant mice: black, lethal yellow, viable yellow, agouti, brown, light, albino, dilute, recessive yellow, pink-eyed dilution, slaty, and silver. It was demonstrated that 1) complete solubilization of melanins in Soluene-350 is a convenient method to estimate the total amount of eu- and pheomelanins, 2) lethal yellow, viable yellow, and recessive yellow hairs contain almost pure pheomelanins, and 3) melanins from brown, light, silver, and pink-eyed black hairs share chemical properties in common that are characterized by partial solubility in strong alkali. We suggest that 1) the brown-type eumelanins have lower degrees of polymerization than the black-type eumelanins, and 2) slaty hair melanin contains a greatly reduced ratio of 5,6-dihydroxyindole-2-carboxylic acid-derived units as compared with black and other eumelanic hair melanins. These results indicate that our methodology, high-performance liquid chromatography and spectrophotometric methods combined, may be useful in chemically characterizing melanin pigments produced in follicular melanocytes.

  4. Synthesis and characterization of melanins from dihydroxyindole-2-carboxylic acid and dihydroxyindole.

    PubMed

    Orlow, S J; Osber, M P; Pawelek, J M

    1992-09-01

    Several studies have confirmed that a melanocyte-specific enzyme, dopachrome tautomerase (EC 5.3.2.3), catalyzes the isomerization of dopachrome to 5,6-dihydroxyindole-2-carboxylic acid (DHICA) (Pawelek, 1991). Here we report that DHICA, produced either enzymatically with dopachrome tautomerase or through chemical synthesis, spontaneously polymerized to form brown melanin that was soluble in aqueous solutions above pH 5. Under the same reaction conditions, solutions of either DOPA, DOPAchrome, or 5,6-dihydroxyindole (DHI) formed black, insoluble melanin precipitates. When DHICA and DHI were mixed together, with DHICA in molar excess, little or no precipitation of DHI-melanin occurred and the rate and extent of soluble melanin formation was markedly enhanced over that achieved with DHICA alone, suggesting co-polymerization of DHICA and DHI. With or without DHI, DHICA-melanins absorbed throughout the ultraviolet and visible spectra (200-600 nm). The DHICA-melanins precipitated below pH 5, at least in part because of protonation of the carboxyl groups. DHICA-melanins could be passed through 0.22 micron filters but could not be dialyzed through semi-permeable membranes with exclusion limits of 12,000-14,000 daltons. HPLC/molecular sieve analyses revealed apparent molecular weights ranging from 20,000 to 200,000 daltons, corresponding to 100-1,000 DHICA monomers per molecule of melanin. DHICA-melanins were stable to boiling, lyophilization, freezing and thawing, and incubation at room temperature for more than 1 year. The natural occurrence of oligomers of DHICA was first reported by Ito and Nichol (1974) in their studies of the brown tapetal pigment in the eye of the sea catfish (Arius felis L.).(ABSTRACT TRUNCATED AT 250 WORDS)

  5. Biosynthesis of catechol melanin from glycerol employing metabolically engineered Escherichia coli.

    PubMed

    Mejía-Caballero, Alejandra; de Anda, Ramón; Hernández-Chávez, Georgina; Rogg, Simone; Martinez, Alfredo; Bolívar, Francisco; Castaño, Victor M; Gosset, Guillermo

    2016-09-22

    Melanins comprise a chemically-diverse group of polymeric pigments whose function is related to protection against physical and chemical stress factors. These polymers have current and potential applications in the chemical, medical, electronics and materials industries. The biotechnological production of melanins offers the possibility of obtaining these pigments in pure form and relatively low cost. In this study, Escherichia coli strains were engineered to evaluate the production of melanin from supplemented catechol or from glycerol-derived catechol produced by an Escherichia coli strain generated by metabolic engineering. It was determined that an improved mutant version of the tyrosinase from Rhizobium etli (MutmelA), could employ catechol as a substrate to generate melanin. Strain E. coli W3110 expressing MutmelA was grown in bioreactor batch cultures with catechol supplemented in the medium. Under these conditions, 0.29 g/L of catechol melanin were produced. A strain with the capacity to synthesize catechol melanin from a simple carbon source was generated by integrating the gene MutmelA into the chromosome of E. coli W3110 trpD9923, that has been modified to produce catechol by the expression of genes encoding a feedback inhibition resistant version of 3-deoxy-D-arabino-heptulosonate 7-phosphate synthase, transketolase and anthranilate 1,2-dioxygenase from Pseudomonas aeruginosa PAO1. In batch cultures with this strain employing complex medium with 40 g/L glycerol as a carbon source, 1.21 g/L of catechol melanin were produced. The melanin was analysed by employing Fourier transform infrared spectroscopy, revealing the expected characteristics for a catechol-derived polymer. This constitutes the first report of an engineered E. coli strain and a fermentation process for producing a catechol melanin from a simple carbon source (glycerol) at gram level, opening the possibility of generating a large quantity of this polymer for its detailed characterization

  6. Melanin concentration gradients in modern and fossil feathers.

    PubMed

    Field, Daniel J; D'Alba, Liliana; Vinther, Jakob; Webb, Samuel M; Gearty, William; Shawkey, Matthew D

    2013-01-01

    In birds and feathered non-avian dinosaurs, within-feather pigmentation patterns range from discrete spots and stripes to more subtle patterns, but the latter remain largely unstudied. A ∼55 million year old fossil contour feather with a dark distal tip grading into a lighter base was recovered from the Fur Formation in Denmark. SEM and synchrotron-based trace metal mapping confirmed that this gradient was caused by differential concentration of melanin. To assess the potential ecological and phylogenetic prevalence of this pattern, we evaluated 321 modern samples from 18 orders within Aves. We observed that the pattern was found most frequently in distantly related groups that share aquatic ecologies (e.g. waterfowl Anseriformes, penguins Sphenisciformes), suggesting a potential adaptive function with ancient origins.

  7. Melanin Concentration Gradients in Modern and Fossil Feathers

    PubMed Central

    Field, Daniel J.; D’Alba, Liliana; Vinther, Jakob; Webb, Samuel M.; Gearty, William; Shawkey, Matthew D.

    2013-01-01

    In birds and feathered non-avian dinosaurs, within-feather pigmentation patterns range from discrete spots and stripes to more subtle patterns, but the latter remain largely unstudied. A ∼55 million year old fossil contour feather with a dark distal tip grading into a lighter base was recovered from the Fur Formation in Denmark. SEM and synchrotron-based trace metal mapping confirmed that this gradient was caused by differential concentration of melanin. To assess the potential ecological and phylogenetic prevalence of this pattern, we evaluated 321 modern samples from 18 orders within Aves. We observed that the pattern was found most frequently in distantly related groups that share aquatic ecologies (e.g. waterfowl Anseriformes, penguins Sphenisciformes), suggesting a potential adaptive function with ancient origins. PMID:23555675

  8. Analysis of the structure of synthetic and natural melanins by solid-phase

    SciTech Connect

    Duff, G.A.; Roberts, J.E.; Foster, N.

    1988-09-06

    The structures of one synthetic and two natural melanins are examined by solid-state NMR using cross polarization, magic angle sample spinning, and high-power proton decoupling. The structural features of synthetic dopa malanin are compared to those of melanin from malignant melanoma cells grown in culture and sepia melanin from squid ink. Natural abundance /sup 13/C and /sup 15/N spectra show resonances consistent with known pyrrolic and indolic structures within the heterogeneous biopolymer; /sup 13/C spectra indicate the presence of aliphatic residues in all three materials. These solid-phase experiments illustrate the promise of solid-phase NMR for elucidating structural from insoluble biomaterials.

  9. An objective assessment of melanin in vitiligo skin treated with Balneo PUVA therapy.

    PubMed

    Hegyi, V; Petrovajová, M; Novotný, M

    2014-02-01

    Visual clinical methods of skin color evaluation for diagnostic purposes are so far mostly subjective and thus inaccurate. We present a modified method of melanin amount measurement based on diffuse reflectance spectroscopy (DRS). This method is non-invasive and objective, and allows easy quantification and comparison of melanin levels. Skin pigmentation was measured by DRS method in 0-18 year old patients at the Department of Pediatric Dermatovenerology, School of Medicine Comenius University Bratislava. Patients were treated for their vitiligo by Balneo PUVA treatment twice weekly. Each patient had measured his remittance spectra from the treated vitiliginous skin before the treatment was started, after 10 irradiations of Balneo PUVA and at the end of the treatment after 25 irradiations of Balneo PUVA. In our study as a reference skin for spectroscopic assessment of melanin in vivo was used the averaged remittance spectra (measured on the inner arm) from the sample of 10 albino patients. The remittance spectra obtained from the vitiligo patients were ratioed against the newly described remittance reference albino skin. We exploited the linear behavior of the spectral curve in the 620-720 nm interval (significant for melanin absorption) and used the slope of the regression line to compute the quantification index α. By clinical examination before the Balneo PUVA therapy, after the 10th dose of Balneo PUVA therapy as well as at the end of the complete course of Balneo PUVA therapy (after 25 irradiations) we recorded a marked increase of pigmentation in all treated patients for their vitiligo. In each patient the values of melanin quantification angle α were calculated. Statistically we found a significant difference between the melanin quantification angle α in vitiliginous skin before, during the 10th dose of treatment and after the treatment. Similar significant difference was also observed between treated and non-involved skin. We could confirm a clear

  10. In vivo and ex vivo epi-mode pump-probe imaging of melanin and microvasculature

    PubMed Central

    Matthews, Thomas E.; Wilson, Jesse W.; Degan, Simone; Simpson, Mary Jane; Jin, Jane Y.; Zhang, Jennifer Y.; Warren, Warren S.

    2011-01-01

    We performed epi-mode pump-probe imaging of melanin in excised human pigmented lesions and both hemoglobin and melanin in live xenograft mouse melanoma models to depths greater than 100 µm. Eumelanin and pheomelanin images, which have been previously demonstrated to differentiate melanoma from benign lesions, were acquired at the dermal-epidermal junction with cellular resolution and modest optical powers (down to 15 mW). We imaged dermal microvasculature with the same wavelengths, allowing simultaneous acquisition of melanin, hemoglobin and multiphoton autofluorescence images. Molecular pump-probe imaging of melanocytes, skin structure and microvessels allows comprehensive, non-invasive characterization of pigmented lesions. PMID:21698020

  11. Screening of micro-organisms for decolorization of melanins produced by bluestain fungi.

    PubMed

    Rättö, M; Chatani, M; Ritschkoff, A C; Viikari, L

    2001-03-01

    A total of 17 fungi and four bacteria were screened for their ability to decolorize melanin, using isolated extracellular melanin of the bluestain fungus Aureobasidium pullulans as substrate. On agar media, decolorization was observed by four fungal strains: Bjerkandera adusta VTT-D-99746, Galactomyces geotrichum VTT-D-84228, Trametes hirsuta VTT-D-95443 and Trametes versicolor VTT-D-99747. The four fungi were more efficient on nitrogen-limited medium than on complete medium. The melanin-decolorizing activity of G. geotrichum appeared to be located on the mycelium and could be liberated into the medium enzymatically.

  12. Bio-Inspired Structural Colors Produced via Self-Assembly of Synthetic Melanin Nanoparticles.

    PubMed

    Xiao, Ming; Li, Yiwen; Allen, Michael C; Deheyn, Dimitri D; Yue, Xiujun; Zhao, Jiuzhou; Gianneschi, Nathan C; Shawkey, Matthew D; Dhinojwala, Ali

    2015-05-26

    Structural colors arising from interactions of light with submicron scale periodic structures have been found in many species across all taxa, serving multiple biological functions including sexual signaling, camouflage, and aposematism. Directly inspired by the extensive use of self-assembled melanosomes to produce colors in avian feathers, we set out to synthesize and assemble polydopamine-based synthetic melanin nanoparticles in an effort to fabricate colored films. We have quantitatively demonstrated that synthetic melanin nanoparticles have a high refractive index and broad absorption spanning across the UV-visible range, similar to natural melanins. Utilizing a thin-film interference model, we demonstrated the coloration mechanism of deposited films and showed that the unique optical properties of synthetic melanin nanoparticles provide advantages for structural colors over other polymeric nanoparticles (i.e., polystyrene colloidal particles).

  13. Lasers in esthetic treatment of gingival melanin hyperpigmentation: a review article.

    PubMed

    Bakhshi, Mahin; Rahmani, Somayeh; Rahmani, Ali

    2015-11-01

    The health and suitability of mouth components play an important role towards defining facial attractiveness. An important component of the oral cavity is the color of the gingival tissue. Gingival melanin hyperpigmentation is caused by several reasons and affects people across ethnicity, race, age, and both gender. Lasers are presently being used for gingival melanin depigmentation. In this article, we reviewed studies on laser parameters, duration of gingival healing, pain perception during and after the operation, scores used for the evaluation of gingival melanin hyperpigmentation, follow-up period, treatment results, and recurrence reports. We conclude that laser ablation for gingival depigmentation is one of the most pleasant, reliable, acceptable, and impressive techniques available for treating gingival melanin hyperpigmentation.

  14. Natural melanin: a potential pH-responsive drug release device.

    PubMed

    Araújo, Marco; Viveiros, Raquel; Correia, Tiago R; Correia, Ilídio J; Bonifácio, Vasco D B; Casimiro, Teresa; Aguiar-Ricardo, Ana

    2014-07-20

    This work proposes melanin as a new nanocarrier for pH-responsive drug release. Melanin is an abundant natural polymer that can be easily extracted from cuttlefish as nanoparticles with a suitable size range for drug delivery. However, despite its high potentiality, the application of this biopolymer in the pharmaceutical and biomedical fields is yet to be explored. Herein, melanin nanoparticles were impregnated with metronidazole, chosen as model antibiotic drug, using supercritical carbon dioxide. The drug release profile was investigated at acidic and physiologic pH, and the dominant mechanism was found to follow a non-Fickian transport. Drug release from melanin shows a strong pH dependency, which allied to its biocompatibility and lack of cytotoxicity envisages its potential application as nanocarrier in formulations for colon and intestine targeted drug delivery.

  15. Royal jelly reduces melanin synthesis through down-regulation of tyrosinase expression.

    PubMed

    Han, Sang Mi; Yeo, Joo Hong; Cho, Yoon Hee; Pak, Sok Cheon

    2011-01-01

    For cosmetic reasons, the demand for effective and safe skin-whitening agents is high. Since the key enzyme in the melanin synthetic pathway is tyrosinase, many depigmenting agents in the treatment of hyperpigmentation act as tyrosinase inhibitors. In this study, we have investigated the hypo-pigmentary mechanism of royal jelly in a mouse melanocyte cell line, B16F1. Treatment of B16F1 cells with royal jelly markedly inhibited melanin biosynthesis in a dose-dependent manner. Decreased melanin content occurred through the decrease of tyrosinase activity. The mRNA levels of tyrosinase were also reduced by royal jelly. These results suggest that royal jelly reduces melanin synthesis by down-regulation of tyrosinase mRNA transcription and serves as a new candidate in the design of new skin-whitening or therapeutic agents.

  16. Melanin and blood concentration in human skin studied by multiple regression analysis: experiments

    NASA Astrophysics Data System (ADS)

    Shimada, M.; Yamada, Y.; Itoh, M.; Yatagai, T.

    2001-09-01

    Knowledge of the mechanism of human skin colour and measurement of melanin and blood concentration in human skin are needed in the medical and cosmetic fields. The absorbance spectrum from reflectance at the visible wavelength of human skin increases under several conditions such as a sunburn or scalding. The change of the absorbance spectrum from reflectance including the scattering effect does not correspond to the molar absorption spectrum of melanin and blood. The modified Beer-Lambert law is applied to the change in the absorbance spectrum from reflectance of human skin as the change in melanin and blood is assumed to be small. The concentration of melanin and blood was estimated from the absorbance spectrum reflectance of human skin using multiple regression analysis. Estimated concentrations were compared with the measured one in a phantom experiment and this method was applied to in vivo skin.

  17. Gamma-resonance study of the reaction of iron ions with synthetic L-dopa melanin

    SciTech Connect

    Bagirov, R.M.; Stukan, R.A.; Lapina, V.A.; Dontsov, A.E.; Ostrovskii, M.A.

    1986-07-01

    The reaction of Fe/sup 3 +/ and Fe/sup 2 +/ ions with synthetic L-dopa melanin, which is a model compound of natural melanin (the melanoprotein granules in the pigment epithelial cells in vertebrate and human eyes), has been studied by gamma-resonance spectroscopy. The investigations showed that L-dopa melanin is capable of effectively binding iron ions and that it displays oxidative or reducing properties with respect to Fe, depending on the composition of the subsystem of the Fe ions and the ambient pH. Trivalent Fe/sup 3 +/ ions form stronger complexes with L-dopa melanin than do Fe/sup 2 +/ ions. The coordination takes place mainly with the carboxyl groups and the amino and imino groups of the polymer. The conformational state of the polymer apparently changes as the pH is varied.

  18. Elemental characterisation of melanin in feathers via synchrotron X-ray imaging and absorption spectroscopy

    PubMed Central

    Edwards, Nicholas P.; van Veelen, Arjen; Anné, Jennifer; Manning, Phillip L.; Bergmann, Uwe; Sellers, William I.; Egerton, Victoria M.; Sokaras, Dimosthenis; Alonso-Mori, Roberto; Wakamatsu, Kazumasa; Ito, Shosuke; Wogelius, Roy A.

    2016-01-01

    Melanin is a critical component of biological systems, but the exact chemistry of melanin is still imprecisely known. This is partly due to melanin’s complex heterogeneous nature and partly because many studies use synthetic analogues and/or pigments extracted from their natural biological setting, which may display important differences from endogenous pigments. Here we demonstrate how synchrotron X-ray analyses can non-destructively characterise the elements associated with melanin pigment in situ within extant feathers. Elemental imaging shows that the distributions of Ca, Cu and Zn are almost exclusively controlled by melanin pigment distribution. X-ray absorption spectroscopy demonstrates that the atomic coordination of zinc and sulfur is different within eumelanised regions compared to pheomelanised regions. This not only impacts our fundamental understanding of pigmentation in extant organisms but also provides a significant contribution to the evidence-based colour palette available for reconstructing the appearance of fossil organisms. PMID:27658854

  19. An update on the honesty of melanin-based color signals in birds.

    PubMed

    McGraw, Kevin J

    2008-04-01

    The control mechanisms and information content of melanin-based color signals in birds have generated much recent interest and controversy among evolutionary biologists. Initial experimental studies on this topic manipulated coarse metrics of an individual's condition (i.e. food intake, disease state) and failed to detect significant condition-dependence of melanin ornament expression. However, three new lines of research appear profitable and target specific factors associated with the production of melanin pigments. These include the role of (i) metals, (ii) amino acids, and (iii) testosterone and social interactions in shaping the extent and intensity of melanin-colored plumage patches. Here, I review recent studies of and evidence for these honesty-reinforcing mechanisms.

  20. Mechanistic insights into the bleaching of melanin by alkaline hydrogen peroxide.

    PubMed

    Smith, R A W; Garrett, B; Naqvi, K R; Fülöp, A; Godfrey, S P; Marsh, J M; Chechik, V

    2017-03-18

    This work aims to determine the roles of reactive oxygen species HO∙ and HO2(-) in the bleaching of melanins by alkaline hydrogen peroxide. Experiments using melanosomes isolated from human hair indicated that the HO∙ radical generated in the outside solution does not contribute significantly to bleaching. However, studies using soluble Sepia melanin demonstrated that both HO2(-) and HO∙ will individually bleach melanin. Additionally, when both oxidants are present, bleaching is increased dramatically in both rate and extent. Careful experimental design enabled the separation of the roles and effects of these key reactive species, HO∙ and HO2(-). Rationalisation of the results presented, and review of previous literature, allowed the postulation of a simplified general scheme whereby the strong oxidant HO∙ is able to pre-oxidise melanin units to o-quinones enabling more facile ring opening by the more nucleophilic HO2(-). In this manner the efficiency of the roles of both species is maximised.

  1. Mechanisms of branching reactions in melanin formation - Ab initio quantum engineering approach -

    NASA Astrophysics Data System (ADS)

    Kishida, Ryo; Menez Aspera, Susan; Kasai, Hideaki

    Melanin, a pigment found in animals, consists of two types of oligomeric unit: eumelanin and pheomelanin. The color of the skin, the hair, and the eyes is controlled by the ratio of eumelanin/pheomelanin production. Especially, dopachrome and dopaquinone are the precursor molecules of melanin which directly affect the composition of melanin through their branching reactions. Dopachrome is converted into two possible monomers of eumelanin. Dopaquinone can undergo both eumelanin and pheomelanin synthesis. To understand the mechanisms and controlling factors that govern the conversions, reactions of the two molecules are investigated using density functional theory-based first-principles calculations. Our results deepen mechanistic understanding of the reactions and open possibilities to design properties and functions of melanin. In this talk, we will discuss about the competitions of the branching reactions.

  2. Melanin and blood concentration in human skin studied by multiple regression analysis: experiments.

    PubMed

    Shimada, M; Yamada, Y; Itoh, M; Yatagai, T

    2001-09-01

    Knowledge of the mechanism of human skin colour and measurement of melanin and blood concentration in human skin are needed in the medical and cosmetic fields. The absorbance spectrum from reflectance at the visible wavelength of human skin increases under several conditions such as a sunburn or scalding. The change of the absorbance spectrum from reflectance including the scattering effect does not correspond to the molar absorption spectrum of melanin and blood. The modified Beer-Lambert law is applied to the change in the absorbance spectrum from reflectance of human skin as the change in melanin and blood is assumed to be small. The concentration of melanin and blood was estimated from the absorbance spectrum reflectance of human skin using multiple regression analysis. Estimated concentrations were compared with the measured one in a phantom experiment and this method was applied to in vivo skin.

  3. Analysis of lysosomal membrane proteins exposed to melanin in HeLa cells

    PubMed Central

    2016-01-01

    Objectives There have been developed to use targeting ability for antimicrobial, anticancerous, gene therapy and cosmetics through analysis of various membrane proteins isolated from cell organelles. Methods It was examined about the lysosomal membrane protein extracted from lysosome isolated from HeLa cell treated by 100 ppm melanin for 24 hours in order to find associated with targeting ability to melanin using by 2-dimensional electrophoresis. Results The result showed 14 up-regulated (1.5-fold) and 13 down-regulated (2.0-fold) spots in relation to melanin exposure. Conclusions It has been found that lysosomal membrane proteins are associated with melanin to decolorize and quantity through cellular activation of lysosome. PMID:27158002

  4. Quick analysis of optical spectra to quantify epidermal melanin and papillary dermal blood content of skin.

    PubMed

    Jacques, Steven L

    2015-04-01

    This paper presents a practical approach for assessing the melanin and blood content of the skin from total diffuse reflectance spectra, R(λ), where λ is wavelength. A quick spectral analysis using just three wavelengths (585 nm, 700 nm and 800 nm) is presented, based on the 1985 work of Kollias and Baquer who documented epidermal melanin of skin using the slope of optical density (OD) between 620 nm and 720 nm. The paper describes the non-rectilinear character of such a quick analysis, and shows that almost any choice of two wavelengths in the 600-900 range can achieve the characterization of melanin. The extrapolation of the melanin slope to 585 nm serves as a baseline for subtraction from the OD (585 nm) to yield a blood perfusion score. Monte Carlo simulations created spectral data for a skin model with epidermis, papillary dermis and reticular dermis to illustrate the analysis.

  5. Elemental characterisation of melanin in feathers via synchrotron X-ray imaging and absorption spectroscopy

    NASA Astrophysics Data System (ADS)

    Edwards, Nicholas P.; van Veelen, Arjen; Anné, Jennifer; Manning, Phillip L.; Bergmann, Uwe; Sellers, William I.; Egerton, Victoria M.; Sokaras, Dimosthenis; Alonso-Mori, Roberto; Wakamatsu, Kazumasa; Ito, Shosuke; Wogelius, Roy A.

    2016-09-01

    Melanin is a critical component of biological systems, but the exact chemistry of melanin is still imprecisely known. This is partly due to melanin’s complex heterogeneous nature and partly because many studies use synthetic analogues and/or pigments extracted from their natural biological setting, which may display important differences from endogenous pigments. Here we demonstrate how synchrotron X-ray analyses can non-destructively characterise the elements associated with melanin pigment in situ within extant feathers. Elemental imaging shows that the distributions of Ca, Cu and Zn are almost exclusively controlled by melanin pigment distribution. X-ray absorption spectroscopy demonstrates that the atomic coordination of zinc and sulfur is different within eumelanised regions compared to pheomelanised regions. This not only impacts our fundamental understanding of pigmentation in extant organisms but also provides a significant contribution to the evidence-based colour palette available for reconstructing the appearance of fossil organisms.

  6. The role of melanin as protector against free radicals in skin and its role as free radical indicator in hair.

    PubMed

    Herrling, Thomas; Jung, Katinka; Fuchs, Jürgen

    2008-05-01

    Throughout the body, melanin is a homogenous biological polymer containing a population of intrinsic, semiquinone-like radicals. Additional extrinsic free radicals are reversibly photo-generated by UV and visible light. Melanin photochemistry, particularly the formation and decay of extrinsic radicals, has been the subject of numerous electron spin resonance (ESR) spectroscopy studies. Several melanin monomers exist, and the predominant monomer in a melanin polymer depends on its location within an organism. In skin and hair, melanin differs in content of eumelanin or pheomelanin. Its bioradical character and its susceptibility to UV irradiation makes melanin an excellent indicator for UV-related processes in both skin and hair. The existence of melanin in skin is strongly correlated with the prevention against free radicals/ROS generated by UV radiation. Especially in the skin melanin (mainly eumelanin) ensures the only natural UV protection by eliminating the generated free radicals/ROS. Melanin in hair can be used as a free radical detector for evaluating the efficacy of hair care products. The aim of this study was to investigate the suitability of melanin as protector of skin against UV generated free radicals and as free radical indicator in hair.

  7. The role of melanin as protector against free radicals in skin and its role as free radical indicator in hair

    NASA Astrophysics Data System (ADS)

    Herrling, Thomas; Jung, Katinka; Fuchs, Jürgen

    2008-05-01

    Throughout the body, melanin is a homogenous biological polymer containing a population of intrinsic, semiquinone-like radicals. Additional extrinsic free radicals are reversibly photo-generated by UV and visible light. Melanin photochemistry, particularly the formation and decay of extrinsic radicals, has been the subject of numerous electron spin resonance (ESR) spectroscopy studies. Several melanin monomers exist, and the predominant monomer in a melanin polymer depends on its location within an organism. In skin and hair, melanin differs in content of eumelanin or pheomelanin. Its bioradical character and its susceptibility to UV irradiation makes melanin an excellent indicator for UV-related processes in both skin and hair. The existence of melanin in skin is strongly correlated with the prevention against free radicals/ROS generated by UV radiation. Especially in the skin melanin (mainly eumelanin) ensures the only natural UV protection by eliminating the generated free radicals/ROS. Melanin in hair can be used as a free radical detector for evaluating the efficacy of hair care products. The aim of this study was to investigate the suitability of melanin as protector of skin against UV generated free radicals and as free radical indicator in hair.

  8. Examination by EPR spectroscopy of free radicals in melanins isolated from A-375 cells exposed on valproic acid and cisplatin.

    PubMed

    Chodurek, Ewa; Zdybel, Magdalena; Pilawa, Barbara; Dzierzewicz, Zofia

    2012-01-01

    Drug binding by melanin biopolymers influence the effectiveness of the chemotherapy, radiotherapy and photodynamic therapy. Free radicals of melanins take part in formation of their complex with drugs. The aim of this work was to determine the effect of the two compounds: valproic acid (VPA) and cisplatin (CPT) on free radicals properties of melanin isolated from A-375 melanoma cells. Free radicals were examined by an X-band (9.3 GHz) electron paramagnetic resonance (EPR) spectroscopy. EPR spectra were measured for the model synthetic eumelanin - DOPA-melanin, the melanin isolated from the control A-375 cells and these cells treated by VPA, CPT and both VPA and CPT. For all the examined samples broad EPR lines (deltaBpp: 0.48-0.68 mT) with g-factors of 2.0045-2.0060 characteristic for o-semiquinone free radicals were observed. Free radicals concentrations (N) in the tested samples, g-factors, amplitudes (A), integral intensities (I) and linewidths (deltaBpp) of the EPR spectra, were analyzed. The EPR lines were homogeneously broadened. Continuous microwave saturation of the EPR spectra indicated that slow spin-lattice relaxation processes existed in all the tested melanin samples. The relatively slowest spin-lattice relaxation processes characterized melanin isolated from A-375 cells treated with both VPA and CPT. The changes of the EPR spectra with increasing microwave power in the range of 2.2-70 mW were evaluated. Free radicals concentrations in the melanin from A-375 cells were higher than in the synthetic DOPA-melanin. The strong increase of free radicals concentration in the melanin from A-375 cells was observed after their treating by VPA. CPT also caused the increase of free radicals concentrations in the examined natural melanin. The free radicals concentration in melanin isolated from A-375 cells treated with both VPA and CPT was slightly higher than those in melanin from the control cells.

  9. Detection of Antibodies against Paracoccidioides brasiliensis Melanin in In Vitro and In Vivo Studies during Infection ▿

    PubMed Central

    Urán, Martha E.; Nosanchuk, Joshua D.; Restrepo, Angela; Hamilton, Andrew J.; Gómez, Beatriz L.; Cano, Luz E.

    2011-01-01

    Several cell wall constituents, including melanins or melanin-like compounds, have been implicated in the pathogenesis of a wide variety of microbial diseases caused by diverse species of pathogenic bacteria, fungi, and helminthes. Among these microorganisms, the dimorphic fungal pathogen Paracoccidioides brasiliensis produces melanin in its conidial and yeast forms. In the present study, melanin particles from P. brasiliensis were injected into BALB/c mice in order to produce monoclonal antibodies (MAbs). We identified five immunoglobulin G1 (IgG1) κ-chain and four IgM melanin-binding MAbs. The five IgG1 κ-chain isotypes are the first melanin-binding IgG MAbs ever reported. The nine MAbs labeled P. brasiliensis conidia and yeast cells both in vitro and in pulmonary tissues. The MAbs cross-reacted with melanin-like purified particles from other fungi and also with commercial melanins, such as synthetic and Sepia officinalis melanin. Melanization during paracoccidioidomycosis (PCM) was also further supported by the detection of IgG antibodies reactive to melanin from P. brasiliensis conidia and yeast in sera and bronchoalveolar lavage fluids from P. brasiliensis-infected mice, as well as in sera from human patients with PCM. Serum specimens from patients with other mycoses were also tested for melanin-binding antibodies by enzyme-linked immunosorbent assay, and cross-reactivities were detected for melanin particles from different fungal sources. These results suggest that melanin from P. brasiliensis is an immunologically active fungal structure that activates a strong IgG humoral response in humans and mice. PMID:21813659

  10. Sexual dimorphism in melanin pigmentation, feather coloration and its heritability in the barn swallow (Hirundo rustica).

    PubMed

    Saino, Nicola; Romano, Maria; Rubolini, Diego; Teplitsky, Celine; Ambrosini, Roberto; Caprioli, Manuela; Canova, Luca; Wakamatsu, Kazumasa

    2013-01-01

    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

  11. Melanin, a promising radioprotector: mechanisms of actions in a mice model.

    PubMed

    Kunwar, A; Adhikary, B; Jayakumar, S; Barik, A; Chattopadhyay, S; Raghukumar, S; Priyadarsini, K I

    2012-10-15

    The radioprotective effect of extracellular melanin, a naturally occurring pigment, isolated from the fungus Gliocephalotrichum simplex was examined in BALB/C mice, and the probable mechanism of action was established. At an effective dose of 50mg/kg body weight, melanin exhibited both prophylactic and mitigative activities, increasing the 30-day survival of mice by 100% and 60%, respectively, after exposure to radiation (7Gy, whole body irradiation (WBI)). The protective activity of melanin was primarily due to inhibition of radiation-induced hematopoietic damages as evidenced by improvement in spleen parameters such as index, total cellularity, endogenous colony forming units, and maintenance of circulatory white blood cells and platelet counts. Melanin also reversed the radiation-induced decrease in ERK phosphorylation in splenic tissue, which may be the key feature in its radioprotective action. Additionally, our results indicated that the sustained activation of AKT, JNK and P38 proteins in splenic tissue of melanin pre-treated group may also play a secondary role. This was also supported by the fact that melanin could prevent apoptosis in splenic tissue by decreasing BAX/Bcl-XL ratio, and increasing the expressions of the proliferation markers (PCNA and Cyclin D1), compared to the radiation control group. Melanin also reduced the oxidative stress in hepatic tissue and abrogated immune imbalance by reducing the production of pro-inflammatory cytokines (IL6 and TNFα). In conclusion, our results confirmed that fungal melanin is a very effective radioprotector against WBI and the probable mechanisms of radioprotection are due to modulation in pro-survival (ERK) signaling, prevention of oxidative stress and immunomodulation.

  12. Ability of melanins to protect against the radiolysis of thymine and thymidine.

    PubMed

    Hill, H Z; Huselton, C; Pilas, B; Hill, G J

    1987-01-01

    Individuals with black skin rarely get skin cancer, and melanomas, tumors arising from pigmented cells, are generally resistant to radiation therapy. The role of melanin in these two phenomena has not been defined, but oxygen-radical species have been implicated in both effects. These studies were undertaken to determine the ability of various melanins to compete for ionizing radiation-produced radicals which destroy nucleic acid bases. The ability of Sigma eumelanin (S-eumelanin) to protect against the radiolysis of thymidine in buffered solutions was compared to the protective ability of seven amino acids, including melanin precursors; bovine serum albumin, as a model protein; ficoll, as a model polysaccharide; and DNA. Both proteins and polysaccharides are known to scavenge hydroxyl radicals in cells. The concentration of thymidine after exposure to gamma radiation was determined by High Performance Liquid Chromatography (HPLC) analysis after removal of insoluble melanin by acid precipitation. S-eumelanin was more effective at competing with thymidine for free radicals than bovine serum albumin, Ficoll, or DNA, but less effective than certain of the small molecules. Several of the above compounds were also examined for ability to protect against thymine radiolysis. In addition, melanins from other sources were compared to S-eumelanin. Of these, enzymatically synthesized phaeomelanin was the most effective. The results indicate that melanins can compete for base- and nucleoside-damaging free radicals more effectively than other cellular macromolecules. Of the small molecules, the phenolic compounds had the greatest scavenging ability. In vivo, melanins are found in melanosomes bound to protein. Therefore, the relevance of these findings to the photo- and radiobiology of melanins in vivo has yet to be determined.

  13. An Ultra-Violet Tolerant Wild-Type Strain of Melanin-Producing Bacillus thuringiensis

    PubMed Central

    Sansinenea, Estibaliz; Salazar, Francisco; Ramirez, Melanie; Ortiz, Aurelio

    2015-01-01

    Background: Bacillus thuringiensis is the most successful biological control agent used in agriculture, forestry and mosquito control. However, the insecticidal activity of the B. thuringiensis formulation is not very stable and rapidly loses its biological activity under field conditions, due to the ultraviolet radiation in sunlight. Melanin is known to absorb radiation therefore photo protection of B. thuringiensis based on melanin has been extensively studied. Objectives: The aim of this study was to find a wild type strain of naturally melanin-producing B. thuringiensis to avoid any mutation or manipulation that can affect the Cry protein content. Materials and Methods: Bacillus thuringiensis strains were isolated from soils of different States of Mexico and pigment extraction was followed by lowering the pH to 2 using 1N HCl. Pigment was characterized by some chemical tests based on its solubility, bleaching by H2O2 and flocculation with FeCl3, and using an Infrared (IR) spectrum. Ultraviolet (UV) irradiation experiment was performed to probe the melanin efficacy. Results: ELI52 strain of B. thuringiensis was confirmed to naturally produce melanin. The Cry protein analysis suggested that ELI52 is probably a B. thuringiensis subsp. israelensis strain with toxic activity against the Diptera order of insects. Ultra Violet protection efficacy of melanin was probed counting total viable colonies after UV radiation and comparing the results with the non-producing melanin strain L-DOPA (L-3, 4-dihydroxyphenylalanine) was also detected in the culture. ELI52 strain showed an antagonistic effect over some common bacteria from the environment. Conclusions: ELI52 wild-type strain of B. thuringiensis is a good bio-insecticide that produces melanin with UV-resistance that is probably toxic against the Diptera order of insects and can inhibit the growth of other environmental bacteria. PMID:26421136

  14. Sexual Dimorphism in Melanin Pigmentation, Feather Coloration and Its Heritability in the Barn Swallow (Hirundo rustica)

    PubMed Central

    Saino, Nicola; Romano, Maria; Rubolini, Diego; Teplitsky, Celine; Ambrosini, Roberto; Caprioli, Manuela; Canova, Luca; Wakamatsu, Kazumasa

    2013-01-01

    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

  15. Melanin is effective in protecting fast and slow growing fungi from various types of ionizing radiation.

    PubMed

    Pacelli, Claudia; Bryan, Ruth A; Onofri, Silvano; Selbmann, Laura; Shuryak, Igor; Dadachova, Ekaterina

    2017-04-01

    Melanin is a ubiquitous pigment with unique physicochemical properties. The resistance of melanized fungi to cosmic and terrestrial ionizing radiation suggests that melanin also plays a pivotal role in radioprotection. In this study, we compared the effects of densely-ionizing deuterons and sparsely-ionizing X-rays on two microscopic fungi capable of melanogenesis. We utilized the fast-growing pathogenic basiodiomycete forming an induced DOPA-melanin, Cryptococcus neoformans (CN); and the slow-growing environmental rock-inhabiting ascomycete synthesizing a constitutive DHN-melanin, Cryomyces antarcticus (CA); melanized and non-melanized counterparts were compared. CA was more resistant to deuterons than CN, and similar resistance was observed for X-rays. Melanin afforded protection against high-dose (1.5 kGy) deuterons for both CN and CA (p-values < 10(-4) ). For X-rays (0.3 kGy), melanin protected CA (p-values < 10(-4) ) and probably CN. Deuterons increased XTT activity in melanized strains of both species, while the activity in non-melanized cells remained stable or decreased. For ATP levels the reverse occurred: it decreased in melanized strains, but not in non-melanized ones, after deuteron exposure. For both XTT and ATP, which reflect the metabolic activity of the cells, larger and more statistically-significant differences as a function of melanization status occurred in CN. Our data show, for the first time, that melanin protected both fast-growing and slow-growing fungi from high doses of deuterons under physiological conditions. These observations may give clues for creating melanin-based radioprotectors. © 2017 Society for Applied Microbiology and John Wiley & Sons Ltd.

  16. Andrographolide suppresses melanin synthesis through Akt/GSK3β/β-catenin signal pathway.

    PubMed

    Zhu, Ping-Ya; Yin, Wei-Han; Wang, Meng-Ran; Dang, Yong-Yan; Ye, Xi-Yun

    2015-07-01

    Tyrosinase (TYR) is the key enzyme controlling the production of melanin. Very few papers have reported that andrographolide can inhibit melanin content. To investigate the effects of andrographolide on melanin synthesis. Cell viability, melanin content, TYR activity, transcriptional and protein expression levels of TYR family and other kinds of proteins involved in melanogenesis were measured after the treatments of andrographolide. It was found that andrographolide decreased melanin content, TYR activity and transcriptional and protein expression of TYR family and microphthalmia-associated transcription factor (MITF) in B16F10 melanoma cells. Data showed andrographolide also decreased melanin content and TYR content in ultraviolet B (UVB) irradiation induced brown guinea pigs. Moreover, we found that melanin content and TYR activity were effectively inhibited in Human Epidermis Melanocyte (HEM) treated with andrographolide at the medium concentrations without apparent effect on cell viability. Results in experiments treated with MG-132 or cycloheximide (CHX) showed that andrographolide lowered the content of β-catenin in cell nucleus resulting from accelerating the degradation of β-catenin. Phosphorylation of glycogen synthase kinase 3β (GSK3β) and Akt decreased simultaneously. 6-Bromoindirubin-3'-oxime (BIO, inhibitor of GSK3β) and insulin-like growth factors-1 (IGF-1, activator of Akt) could reverse the decline of β-catenin in B16F10 cells induced by andrographolide. These results demonstrate that andrographolide can effectively suppress melanin content and TYR activity in B16F10 cells, HEM cells and UVB-induced brown guinea pig skin by decreasing phosphorylation of GSK3β dependent on Akt, promoting the degradation of β-catenin, inhibiting β-catenin into the nucleus and decreasing the expression of MITF and TYR family. Data indicate that andrographolide may be a potential whiting agent which can have great market in cosmetics and in clinical such as

  17. Melanin Externalization in Candida albicans Depends on Cell Wall Chitin Structures▿

    PubMed Central

    Walker, Claire A.; Gómez, Beatriz L.; Mora-Montes, Héctor M.; Mackenzie, Kevin S.; Munro, Carol A.; Brown, Alistair J. P.; Gow, Neil A. R.; Kibbler, Christopher C.; Odds, Frank C.

    2010-01-01

    The fungal pathogen Candida albicans produces dark-pigmented melanin after 3 to 4 days of incubation in medium containing l-3,4-dihydroxyphenylalanine (l-DOPA) as a substrate. Expression profiling of C. albicans revealed very few genes significantly up- or downregulated by growth in l-DOPA. We were unable to determine a possible role for melanin in the virulence of C. albicans. However, we showed that melanin was externalized from the fungal cells in the form of electron-dense melanosomes that were free or often loosely bound to the cell wall exterior. Melanin production was boosted by the addition of N-acetylglucosamine to the medium, indicating a possible association between melanin production and chitin synthesis. Melanin externalization was blocked in a mutant specifically disrupted in the chitin synthase-encoding gene CHS2. Melanosomes remained within the outermost cell wall layers in chs3Δ and chs2Δ chs3Δ mutants but were fully externalized in chs8Δ and chs2Δ chs8Δ mutants. All the CHS mutants synthesized dark pigment at equivalent rates from mixed membrane fractions in vitro, suggesting it was the form of chitin structure produced by the enzymes, not the enzymes themselves, that was involved in the melanin externalization process. Mutants with single and double disruptions of the chitinase genes CHT2 and CHT3 and the chitin pathway regulator ECM33 also showed impaired melanin externalization. We hypothesize that the chitin product of Chs3 forms a scaffold essential for normal externalization of melanosomes, while the Chs8 chitin product, probably produced in cell walls in greater quantity in the absence of CHS2, impedes externalization. PMID:20543065

  18. Effect of ambient humidity on UV/visible photodegradation of melanin thin films.

    PubMed

    Sharma, Anup

    2010-01-01

    Photodegradation of spin-coated thin films of melanin is investigated using UVA and visible light from light-emitting diodes. The gradual increase in transmitted light through the film is measured as melanin photodegrades over the course of several hours. The photodegradation rate is measured for wavelengths in the 365-600 nm range. It is found that the increase in ambient humidity significantly accelerates the photodegradation process. Implications of these observations for evolution of melanism in biological systems are discussed.

  19. Arbutin encapsulated micelles improved transdermal delivery and suppression of cellular melanin production.

    PubMed

    Liang, Ke; Xu, Keming; Bessarab, Dmitri; Obaje, Jonathan; Xu, Chenjie

    2016-04-30

    Hyperpigmentation is a skin disorder characterized by elevated production of melanin. Current treatment approaches mainly rely on the application of skin lightening chemicals, most of which have safety issues. Efficacy of delivery of the active ingredients to the target organ has also been a challenge. Transdermal based drug delivery platform has been shown to improve drug bioavailability, avoiding the hepatic first pass metabolism, decrease gastrointestinal side effects, and eventually enhance patient compliance. This article explores the utilization of micellar transdermal delivery technology to improve skin penetration and efficacy of arbutin, a hyperpigmentation agent. The suppression efficacy of cellular melanin production versus cell viability of four active ingredients commonly used in skin lightening products, namely allantoin, arbutin, glycolic acid, and hyaluronic acid were first compared. Arbutin was selected for the micellar delivery studies base on its comparatively low cytotoxicity and better performance in reducing melanin production. Micellar Arbutin cream was formulated using Urah® proprietary micellar technology and was assessed for its cellular melanin suppression efficacy and skin penetration capacity. The results show that micellar arbutin cream improved both the delivery and cellular melanin suppression, suggesting that micellar transdermal delivery may have potential application in addressing hyperpigmentation skin disorders. Graphical abstract Transdermal delivery of arbutin with micelles for melanin production suppression.

  20. Characterization and biological activities of extracellular melanin produced by Schizophyllum commune (Fries).

    PubMed

    Arun, G; Eyini, M; Gunasekaran, P

    2015-06-01

    Melanins are enigmatic pigments produced by a wide variety of microorganisms including bacteria and fungi. Here, we have isolated and characterized extracellular melanin from mushroom fungus, Schizophyllum commune. The extracellular dark pigment produced by the broth culture of S. commune, after 21 days of incubation was recovered by hot acid-alkali treatment. The melanin nature of the pigment was characterized by biochemical tests and further, confirmed by UV, IR, EPR, NMR and MALDI-TOF Mass Spectra. Extracellular melanin, at 100 μg/ml, showed significant antibacterial activity against Escherichia coli, Bacillus subtilis, Klebsiella pneumoniae and Pseudomonas fluorescens and antifungal activity against Trichophyton simii and T. rubrum. At a concentration of 50 μg/ml, melanin showed high free radical scavenging activity of DPPH (2,2-diphenyl-1-picrylhydrazyl) indicating its antioxidant potential. It showed concentration dependent inhibition of cell proliferation of Human Epidermoid Larynx Carcinoma Cell Line (HEP-2). This study has demonstrated characterization of melanin from basidiomycetes mushroom fungus, Schizophyllum commune and its applications.

  1. Production and Characterization of Melanin by Submerged Culture of Culinary and Medicinal Fungi Auricularia auricula.

    PubMed

    Zhang, Min; Xiao, Gongnian; Thring, Ronald W; Chen, Wan; Zhou, Huabin; Yang, Hailong

    2015-05-01

    Natural melanin is of great potential value and application in the fields of pharmacology, cosmetics, and functional foods. In the present study, statistically designed experiments were conducted for the optimization of the media to enhance the production of melanin by submerged culture of Auricularia auricula. Glucose, tyrosine, peptone, and CaCO3 were found to have significant effects (P < 0.015) on melanin biosynthesis by a Plackett-Burman experimental design and subsequently optimized using response surface methodology. Optimal media were obtained at the following concentrations: glucose, 0.90 g/L; tyrosine, 6.68 g/L; peptone, 6.99 g/L; and CaCO3, 6.75 g/L. The validity of the optimum media was verified in separate experiments in which the melanin yield of 1008.08 mg/L was obtained under optimum conditions, compared with 306.52 mg/L at other conditions, i.e., a 3.29-fold increase. Furthermore, the important physical and chemical properties of A. auricula melanin were determined. The findings from the present study indicate that large-scale production of natural melanin by submerged culture of A. auricular could be a useful approach.

  2. High-level production of melanin by a novel isolate of Streptomyces kathirae.

    PubMed

    Guo, Jing; Rao, Zhiming; Yang, Taowei; Man, Zaiwei; Xu, Meijuan; Zhang, Xian

    2014-08-01

    Forty-five bacterial strains that produced diffusive pigments were isolated from 40 soil samples. Maximum pigment production was from a Streptomyces kathirae strain designated SC-1. The diffused pigment was characterized by UV-visual and infrared spectroscopy, MS and (1) H nuclear magnetic resonance imaging, and was confirmed as melanin. This may be the first report of melanin production by S. kathirae. To enhance melanin production, the culture medium was optimized by conducting a series of batch fermentations in a defined medium, and the results were analysed statistically using a response surface method. The optimal culture medium comprised 3.3 g L(-1) amylodextrine, 37 g L(-1) yeast extract, 5 g L(-1) NaCl, 0.1 g L(-1) CaCl2 and 54.4 μM CuSO4 . The pH of this medium was 6.0. Under optimal conditions, the melanin concentration was maximized at 13.7 g L(-1) , c. 8.6-fold higher than obtained in suboptimal medium. To our knowledge, the results provide novel data on melanin fermentation, and identify an excellent candidate for industrial-scale microbial fermentation of melanin.

  3. Preparation of melanin from Catharsius molossus L. and preliminary study on its chemical structure.

    PubMed

    Xin, Chao; Ma, Jia-hua; Tan, Cheng-jia; Yang, Zhou; Ye, Feng; Long, Chan; Ye, Shuang; Hou, Da-bin

    2015-04-01

    A great deal of melanin was found in the waste alkali liquor produced by extraction of chitin from Catharsius molossus L. Discarding the lye could harm the environment and cause waste of resources. In this paper, melanin from C. molossus L. was recovered through acid precipitation and purified by pepsin and so on. The purity, chemical composition and structure of the prepared melanin were explored by UV-visible absorption spectroscopy, Fourier transform infrared spectroscopy, proton nuclear magnetic resonance spectroscopy, high resolution (13)C Cross polarization magic angle spinning nuclear magnetic resonance spectroscopy pyrolysis gas chromatography mass spectrometry, X ray diffraction, X ray fluorescence, matrix-assisted laser desorption/ionization time of flight tandem mass spectrometry, thermal analysis, and so on. The results showed that the purity of the prepared melanin was higher than the commercial standard melanin and it was a kind of nanoaggregates composed of a large quantity of 5,6-dihydroxyindole eumelanin and a small amount of phaeomelanin. In addition, the prepared melanin was irregular in shape and its structure could be divided into three levels: advanced structure maintained by polypeptides, substructure maintained by the ferric ion and microstructure. In particular, the smallest structural unit showed the graphite-like layered structure containing five layers linked by non-covalent bonds and each layer mainly consisted of 5,6-dihydroxyindole and its derivatives, which might be connected to each other through various chemical bonds.

  4. Purification and physiochemical characterization of melanin pigment from Klebsiella sp. GSK.

    PubMed

    Sajjan, Shrishailnath; Kulkarni, Guruprasad; Yaligara, Veeranagouda; Kyoung, Lee; Karegoudar, T B

    2010-11-01

    The bacterium capable of producing melanin pigment in the presence of L-tyrosine was isolated from crop field soil sample and identified as Klebsiella sp. GSK based on morphological, biochemical and 16S rDNA sequencing. The polymerization of this pigment occurs outside the cell wall, which has granular structure as melanin ghosts. The chemical characterization of pigment particles showed acid resistant, alkali soluble, insoluble in most of the organic solvents and water. The pigment gets bleached when subjected to the action of oxidants as well as reductants. This pigment was precipitated with FeCl3, ammoniacal silver nitrate and potassium ferricynide. The pigment showed high absorbance in the UV region and decreased absorbance when shifted towards the visible region. The melanin pigment was further charecterized by FT-IR and EPR spectroscopy. A key enzyme 4-hydroxyphenylacetic acid hydroxylase catalyzes the formation of melanin pigment by hydroxylation of L-tyrosine was detected in this bacterium. Inhibition studies with specific inhibitor kojic acid and KCN proved that melanin is synthesized by DOPA-Melanin pathway.

  5. UV causation of melanoma in Xiphophorus is dominated by melanin photosensitized oxidant production

    PubMed Central

    Wood, Simon R.; Berwick, Marianne; Ley, Ronald D.; Walter, Ronald B.; Setlow, Richard B.; Timmins, Graham S.

    2006-01-01

    Controversy continues both as to which wavelengths of sunlight cause melanoma and the mechanisms by which these different wavelengths act. Direct absorption of UVB by DNA is central in albino animal models, but melanin-pigmented models have shown major contributions by wavelengths longer than UVB that are thought to be mediated by photosensitized oxidant production. The only model for which the action spectrum of melanoma causation is known is a genetically melanoma-susceptible specific cross of Xiphophorus fish. We used electron paramagnetic resonance to quantitatively detect the UV induction of reactive melanin radicals in situ in the melanin-containing cells in the skin of this model and derived the action spectrum for melanin-photosensitized oxidant production (Φox). This action spectrum was identical to that for melanoma induction (Φmel). These results confirm the hypothesis that melanin-photosensitized radical production is the major causative step of melanoma in this model and demonstrate that the wavelengths and mechanisms of melanoma causation in different models are dependent on the presence of melanin. This approach should be applicable to humans, thus providing an accurate surrogate for Φmel for prevention studies. PMID:16537493

  6. The interaction of melanin with ionizing and UVC radiations: Characterization of thymine damage

    SciTech Connect

    Huselton, C.A.

    1988-01-01

    These studies were undertaken to determine whether melanin could protect DNA against the harmful effects of ionizing or UVC radiations. A simple, in vitro, model system was developed to evaluate eumelanin (Sigma melanin) as a radioprotector of solutions of 0.1 mM thymine or thymidine exposed to 570Gy of ionizing radiation. Sigma melanin was compared to several amino acids, other biomolecules or to other forms of melanin. To investigate the role of melanin as a passive screen of UVC radiation, melanotic (I{sub 3}), amelanotic (AMEL) cells (both derived from a Cloudman S91 melanoma) and non-melanotic (EMT6) cells were labelled with radioactive dTHd and exposed to 0, 1, 5 or 10KJ/m{sup 2} of UVC. The DNA was extracted; the bases hydrolyzed with concentrated HCl. Thymine bases were separated by reverse phase HPLC. No difference in dimer content was observed between I{sub 3} and AMEL cells, but EMT6 cells had nearly twice the amount of dimer. Overall thymine degradation was more pronounced in I{sub 3} cells than in the other two cell lines, due to the production of non-dimer thymine damage. This damage was identified as thymine glycol by HPLC and mass spectrometry. Melanin, upon exposure to UVC, appears to enhance thymine damage by producing oxidative damage.

  7. Imaging of Melanin Disruption in Age-Related Macular Degeneration Using Multispectral Imaging.

    PubMed

    Dugel, Pravin U; Zimmer, Cheryl N

    2016-02-01

    To investigate whether multispectral imaging (MSI) is able to obtain a noninvasive view of melanin disruption associated with age-related macular degeneration (AMD), which could support early diagnosis and potential treatment strategies. A single retinal center, retrospective, observational, image analysis study of MSI images of 43 patients was done to determine the extent of melanin pigment exhibited in association with AMD, based on the Age-Related Eye Disease Study classification and grading scale. Corresponding fundus photos were also graded for 12 of the eyes. Fifty-one of 61 eyes (84%) of 43 patients with AMD were determined to have melanin disruption in their MSI images in at least the central and/or one of four inner ETDRS areas. There was a relationship between severity of disease and the degree of melanin disruption. The sensitivity of fundus photography for melanin pigment as compared to MSI was only 62.5%, with three false-negatives. A direct, noninvasive, unobstructed view of melanin disruption associated with AMD can be observed using MSI. Copyright 2016, SLACK Incorporated.

  8. Influence of melanin on mutation load in Drosophila populations after long-term irradiation

    SciTech Connect

    Mosse, I.B.; Lyakh, I.P.

    1994-09-01

    The effect of melanin on the level of mutation load has been studied in experimental Drosophila populations exposed to radiation for 115 generations. Four types of populations have been analyzed: (1) control; (2) treated with melanin; (3) irradiated; (4) irradiated and treated with melanin. Melanin was produced by auto-oxidation of 1-dioxyphenylallanine and was constantly added to food. Populations were X-irradiated twice in each generation (at the larvae stage with 6 Gy and at the imago stage with 9 Gy). The level of recessive mutation on the third chromosome was analyzed by a standard genetic method of balanced lethals. The data obtained have shown that the populations exposed to long-term irradiation have the greatest number of mutations decreasing viability. Melanin exhibited radioprotective properties-it reduced the percentage of lethal, semilethal and subvital mutations. Thus the possibility of effective protection of populations exposed to radiation for many generations by melanin has been shown for the first time. 19 refs., 1 fig., 1 tab.

  9. Nitroxides as redox probes of melanins: dark-induced and photoinduced changes in redox equilibria

    SciTech Connect

    Sarna, T.; Korytowski, W.; Sealy, R.C.

    1985-05-15

    The interaction of nitroxide free radicals and their reduced products (hydroxylamines) with synthetic and natural melanins has been studied. Electron spin resonance spectroscopy was used to measure changes in radical concentration in the dark and during irradiation with visible or uv light. Some reduction of nitroxide occurs in the dark, and is reversible: the nitroxide can be completely regenerated by the one-electron oxidant ferricyanide. The kinetics of the process depend strongly on radical charge and pH. For positively charged nitroxides the rate is much faster than for either neutral or anionic radicals. At pH 10 the rate is about 20 times faster than at pH 5. Oxidation of hydroxylamine also can occur so that a redox equilibrium is established. The equilibrium constant has been estimated for the reaction between a nitroxide and melanin from autoxidation of 3,4-dihydroxyphenylalanine. Results are also dependent upon the type of melanin used and chemical modification (oxidation or reduction) of the melanin. Redox equilibria are altered during irradiation with either visible or uv light. Rapid oxidation of hydroxylamine to nitroxide is apparent, together with a slower reduction of nitroxide. Action spectra for these processes are related to those for melanin radical production and oxygen consumption in nitroxide-free melanin systems. Reduction of nitroxide is inhibited by oxygen, suggesting a competition between nitroxide and oxygen for photoinduced reducing equivalents.

  10. Melanin from the Nitrogen-Fixing Bacterium Azotobacter chroococcum: A Spectroscopic Characterization

    PubMed Central

    Banerjee, Raja

    2014-01-01

    Melanins, the ubiquitous hetero-polymer pigments found widely dispersed among various life forms, are usually dark brown/black in colour. Although melanins have variety of biological functions, including protection against ultraviolet radiation of sunlight and are used in medicine, cosmetics, extraction of melanin from the animal and plant kingdoms is not an easy task. Using complementary physicochemical techniques (i.e. MALDI-TOF, FTIR absorption and cross-polarization magic angle spinning solid-state 13C NMR), we report here the characterization of melanins extracted from the nitrogen-fixing non-virulent bacterium Azotobacter chroococcum, a safe viable source. Moreover, considering dihydroxyindole moiety as the main constituent, an effort is made to propose the putative molecular structure of the melanin hetero-polymer extracted from the bacterium. Characterization of the melanin obtained from Azotobacter chroococcum would provide an inspiration in extending research activities on these hetero-polymers and their use as protective agent against UV radiation. PMID:24416247

  11. Modeling drug-melanin interaction with theoretical linear solvation energy relationships.

    PubMed

    Lowrey, A H; Famini, G R; Loumbev, V; Wilson, L Y; Tosk, J M

    1997-10-01

    The affinity of drugs and other xenobiotic agents for melanin is a well-known phenomenon, often occurring with serious physiological consequences. For example, the interaction of anti-psychotic drugs with neuromelanin may play a pivotal role in the induction of extrapyramidal movement disorders associated with the chronic administration of phenothiazine and other neuroleptic agents. Little, however, is known about the complete nature of melanin-drug binding and the impact of these interactions on the physico-chemical properties of melanin. Data, such as binding affinities, can be analyzed using recently developed computational methods that combine mathematical models of chemical structure with statistical analysis. In particular, theoretical linear solvation energy relationships provide a convenient model for understanding and predicting biological, chemical, and physical properties. By using this modeling technique, drug-melanin binding of a set of 16 compounds has been analyzed with correlation analysis and a set of theoretical molecular parameters in order to better understand and characterize drug-melanin interactions. The resulting correlation equation supports a charge transfer model for drug-melanin complex formation and can also be used to estimate binding constants for related compounds.

  12. Protein, lipid, and DNA radicals to measure skin UVA damage and modulation by melanin.

    PubMed

    Haywood, Rachel; Rogge, Fabrice; Lee, Martin

    2008-03-15

    Afro-Caribbeans have a lower incidence of skin cancer than Caucasians, but the effectiveness of melanin as a photoprotective pigment is debated. We investigated the UVA and solar irradiation of ex vivo human skin and DMPO using electron spin resonance spectroscopy, to determine whether pigmented skin is protected by melanin against free radical damage. Initial ascorbate radicals in Caucasian skin were superseded by lipid and/or protein radical adducts with isotropic (a(H)=1.8 mT) and anisotropic spectra comparable to spectra in irradiated pig fat (a(H)=1.9 mT) and BSA. DNA carbon-centered radical adducts (a(H)=2.3 mT) and a broad singlet were detected in genomic DNA/melanin but were not distinguishable in irradiated Caucasian skin. Protein and lipid radicals (n=6 in Caucasian skin) were minimal in Afro-Caribbean skin (n=4) and intermediate skin pigmentations were variable (n=3). In irradiated Afro-Caribbean skin a shoulder to the melanin radical (also in UVA-irradiated pigmented melanoma cells and genomic DNA/melanin and intrinsic to pheomelanin) was detected. In this sample group, protein (but not lipid) radical adducts decreased directly with pigmentation. ESR/spin trapping methodology has potential for screening skin susceptibility to aging and cancer-related radical damage and for measuring protection afforded by melanin, sunscreens, and antiaging creams.

  13. BmPAH Catalyzes the Initial Melanin Biosynthetic Step in Bombyx mori

    PubMed Central

    Chen, Ping; Li, Li; Wang, Jiying; Li, Haiyin; Li, Yan; Lv, Yin; Lu, Cheng

    2013-01-01

    Pigmentation during insect development is a primal adaptive requirement. In the silkworm, melanin is the primary component of larval pigments. The rate limiting substrate in melanin synthesis is tyrosine, which is converted from phenylalanine by the rate-limiting enzyme phenylalanine hydroxylase (PAH). While the role of tyrosine, derived from phenylalanine, in the synthesis of fiber proteins has long been known, the role of PAH in melanin synthesis is still unknown in silkworm. To define the importance of PAH, we cloned the cDNA sequence of BmPAH and expressed its complete coding sequence using the Bac-to-Bac baculovirus expression system. Purified recombinant protein had high PAH activity, some tryptophan hydroxylase activity, but no tyrosine hydroxylase activity, which are typical properties of PAH in invertebrates. Because melanin synthesis is most robust during the embryonic stage and larval integument recoloring stage, we injected BmPAH dsRNA into silkworm eggs and observed that decreasing BmPAH mRNA reduced neonatal larval tyrosine and caused insect coloration to fail. In vitro cultures and injection of 4th instar larval integuments with PAH inhibitor revealed that PAH activity was essential for larval marking coloration. These data show that BmPAH is necessary for melanin synthesis and we propose that conversion of phenylalanine to tyrosine by PAH is the first step in the melanin biosynthetic pathway in the silkworm. PMID:23991017

  14. Manassantin A and B from Saururus chinensis inhibiting cellular melanin production.

    PubMed

    Seo, Chang-Seob; Lee, Won-Hee; Chung, Hee-Wook; Chang, Eun Ju; Lee, Seung Ho; Jahng, Yurngdong; Hwang, Bang Yeon; Son, Jong-Keun; Han, Sang-Bae; Kim, Youngsoo

    2009-11-01

    Hyperpigmentation disorders such as freckles and senile lentigines in the skin are associated with abnormal accumulation of melanin pigments. In this study, two lignan constituents were isolated from Saururus chinensis Baill (Saururaceae) as inhibitors of cellular melanin production by bioassay-guided fractionations. The active constituents were manassantin A and B that dose-dependently inhibited melanin production in alpha-melanocyte stimulating hormone (alpha-MSH)-activated melanoma B16 cells with IC(50) values of 13 nm and 8 nm, respectively. Arbutin as a positive control exhibited an IC(50) value of 96 microm on alpha-MSH-induced melanin production. Further, manassantin A inhibited forskolin- or 3-isobutyl-1-methylxanthine (IBMX)-induced melanin production with IC(50) values of 14 nm or 12 nm, respectively. Manassantin A decreased cellular amounts of IBMX-inducible tyrosinase protein but could not affect the catalytic activity of cell-free tyrosinase, a key enzyme in the biosynthetic pathway of melanin pigments. Finally, this study could provide a pharmacological potential of S. chinensis in hyperpigmentation disorders.

  15. Two-color excited-state absorption imaging of melanins

    NASA Astrophysics Data System (ADS)

    Fu, Dan; Ye, Tong; Matthews, Thomas E.; Yurtsever, Gunay; Hong, Lian; Simon, John D.; Warren, Warren S.

    2007-02-01

    We have demonstrated a new method for imaging melanin with two-color excited state absorption microscopy. If one of two synchronized mode-locked pulse trains at different colors is intensity modulated, the modulation transfers to the other pulse train when nonlinear absorption takes place in the medium. We can easily measure 10 -6 absorption changes caused by either instantaneous two-photon absorption or relatively long lived excited state absorption with a RF lock-in amplifier. Eumelanin and pheomelanin exhibit similar excited state dynamics. However, their difference in excited state absorption and ground state absorption leads to change in the phase of the transient absorption signal. Scanning microscopic imaging is performed with B16 cells, melanoma tissue to demonstrate the 3D high resolution imaging capability. Different melanosome samples are also imaged to illustrate the differences between eumelanin and pheomelanin signals. These differences could enable us to image their respective distribution in tissue samples and provide us with valuable information in diagnosing malignant transformation of melanocytes.

  16. Non-toxic melanin production inhibitors from Garcinia livingstonei (Clusiaceae).

    PubMed

    Mulholland, Dulcie A; Mwangi, Elizabeth M; Dlova, Ncoza C; Plant, Nick; Crouch, Neil R; Coombes, Phillip H

    2013-09-16

    The stem bark of Garcinia livingstonei is used traditionally as a skin lightening agent. To isolate and identify compounds responsible for the observed skin lightening activity of Garcinia livingstonei and to evaluate their cytotoxicity. Constituents of the stem bark and fruits of Garcinia livingstonei were isolated using chromatographic techniques and structures were determined using 1D and 2D NMR and MS analysis. MeWo cells were used to evaluate the cytotoxicity and impact on melanin levels of extracts and compounds isolated, in vitro. Twelve known compounds, morelloflavone (1), morelloflavone-7″-sulphate (2), guttiferone A (3), sargaol (4), isojacareubin (5), 6-deoxyisojacareubin (6) and in addition to the common triterpenoids, betulin, betulin aldehyde, lupeol, lupenone, euphol and stigmasterol were isolated in this investigation. Morelloflavone, morelloflavone-7″-sulphate and sargaol, were found to be considerably less cytotoxic and more effective as skin lightening agents than hydroquinone. A range of compounds was isolated from the stem bark and fruit of Garcinia livingstonei. Although the bark extract contained the cytotoxic guttiferone A, it was found to be less toxic than hydroquinone, and morelloflavone, the 7″-sulphate derivative and sargaol show potential for development as depigmentation/skin lightening agents. © 2013 Elsevier Ireland Ltd. All rights reserved.

  17. Design of a Monocular Multi-Spectral Skin Detection, Melanin Estimation, and False-Alarm Suppression System

    DTIC Science & Technology

    2010-03-01

    Design of a Monocular Multi-Spectral Skin Detection, Melanin Estimation, and False-Alarm Suppression System THESIS Keith R. Peskosky, Second...Skin Detection, Melanin Estimation, and False-Alarm Suppression System THESIS Presented to the Faculty Department of Electrical and Computer Engineering...alarm reduction, and melanin estimation system is designed targeting search and rescue (SAR) with application to special operations for manhunting and

  18. Redox activity of melanin from the ink sac of Sepia officinalis by means of colorimetric oxidative assay.

    PubMed

    Srisuk, Pathomthat; Correlo, Vitor M; Leonor, Isabel B; Palladino, Pasquale; Reis, Rui L

    2016-01-01

    The redox properties of natural extract from cuttlefish ink sac (Sepia officinalis) and synthetic melanin used as a biomimetic in melanin structural investigation were determined by comparison of this phenol-based heterogeneous pigment with gallic acid used as a standard in Folin-Ciocalteu colorimetric assay widely employed for characterisation of oxidative properties of biomaterials. Reactivity of sepia melanin reported here is much higher than previously indicated and this protocol should allow the redox characterisation of all melanins irrespective of their origin and composition.

  19. Photoprotection of human retinal pigment epithelium cells against blue light-induced apoptosis by melanin free radicals from Sepia officinalis.

    PubMed

    Seagle, Brandon-Luke L; Gasyna, Elzbieta M; Mieler, William F; Norris, James R

    2006-11-07

    Cultured retinal pigment epithelium (RPE) cells can phagocytize large foreign particles. Heterogeneous melanin aggregates from Sepia officinalis, a species of cuttlefish, were fed to cultured human RPE cells to produce cells laden with Sepia melanin. Blue light-induced apoptosis (BLIA) assays were performed by flow cytometry on parallel cultures consisting of RPE cells isolated from independent eyes and evenly divided into two cultures, one fed Sepia melanin and one containing only native melanin. After culturing and growth of the cells under blue light illumination for 7 days, the apoptosis percentage of all cultures indicated that Sepia feeding significantly reduced BLIA. To account for Sepia photoprotection, continuous-wave EPR and time-resolved EPR experiments were performed with parallel RPE cultures by using UV (355 nm) and green (532 nm) laser irradiation. Continuous-wave EPR spectra prove that the concentrations of intrinsic and extrinsic melanin free radicals in the Sepia-RPE culture are large compared with those concentrations in the RPE culture. Time-resolved EPR spectra indicate that both UV and green light produced extrinsic melanin radicals as radical pairs from the triplet manifold with a linear dependence on the number of photons per second. These experiments conclusively demonstrate that decreased RPE susceptibility to BLIA correlates with increased intracellular melanin free radical concentrations and that nonnative melanin can supplement native melanin photoprotection of RPE cells.

  20. Melanin dependent survival of Apergillus fumigatus conidia in lung epithelial cells.

    PubMed

    Amin, Shayista; Thywissen, Andreas; Heinekamp, Thorsten; Saluz, Hans Peter; Brakhage, Axel A

    2014-07-01

    Aspergillus fumigatus is the most important air-borne pathogenic fungus of humans. Upon inhalation of conidia, the fungus makes close contact with lung epithelial cells, which only possess low phagocytic activity. These cells are in particular interesting to address the question whether there is some form of persistence of conidia of A. fumigatus in the human host. Therefore, by also using uracil-auxotrophic mutant strains, we were able to investigate the interaction of A549 lung epithelial cells and A. fumigatus conidia in detail for long periods. Interestingly, unlike professional phagocytes, our study showed that the presence of conidial dihydroxynaphthalene (DHN) melanin enhanced the uptake of A. fumigatus conidia by epithelial cells when compared with non-pigmented pksP mutant conidia. Furthermore, conidia of A. fumigatus were able to survive within epithelial cells. This was due to the presence of DHN melanin in the cell wall of conidia, because melanised wild-type conidia showed a higher survival rate inside epithelial cells and led to inhibition of acidification of phagolysosomes. Both effects were not observed for white (non-melanised) conidia of the pksP mutant strain. Moreover, in contrast to pksP mutant conidia, melanised wild-type conidia were able to inhibit the extrinsic apoptotic pathway in A549 lung epithelial cells even for longer periods. The anti-apoptotic effect was not restricted to conidia, because both conidia-derived melanin ghosts (cell-free DHN melanin) and a different type of melanin, dihydroxyphenylalanine (DOPA) melanin, acted anti-apoptotically. Taken together, these data indicate the possibility of melanin-dependent persistence of conidia in lung epithelial cells.

  1. Melanin-Like Pigment Synthesis by Soil Bacillus weihenstephanensis Isolates from Northeastern Poland.

    PubMed

    Drewnowska, Justyna M; Zambrzycka, Monika; Kalska-Szostko, Beata; Fiedoruk, Krzysztof; Swiecicka, Izabela

    2015-01-01

    Although melanin is known for protecting living organisms from harmful physical and chemical factors, its synthesis is rarely observed among endospore-forming Bacillus cereus sensu lato. Here, for the first time, we reported that psychrotolerant Bacillus weihenstephanensis from Northeastern Poland can produce melanin-like pigment. We assessed physicochemical properties of the pigment and the mechanism of its synthesis in relation to B. weihenstephanensis genotypic and phenotypic characteristics. Electron paramagnetic resonance (EPR) spectroscopy displayed a stable free radical signal of the pigment from environmental isolates which are consistent with the commercial melanin. Fourier transform infrared spectroscopy (FT-IR) and physicochemical tests indicated the phenolic character of the pigment. Several biochemical tests showed that melanin-like pigment synthesis by B. weihenstephanensis was associated with laccase activity. The presence of the gene encoding laccase was confirmed by the next generation whole genome sequencing of one B. weihenstephanensis strain. Biochemical (API 20E and 50CHB tests) and genetic (Multi-locus Sequence Typing, 16S rRNA sequencing, and Pulsed-Field Gel Electrophoresis) characterization of the isolates revealed their close relation to the psychrotrophic B. weihenstephanensis DSMZ 11821 reference strain. The ability to synthesize melanin-like pigment by soil B. weihenstephanensis isolates and their psychrotrophic character seemed to be a local adaptation to a specific niche. Detailed genetic and biochemical analyses of melanin-positive environmental B. weihenstephanensis strains shed some light on the evolution and ecological adaptation of these bacteria. Moreover, our study raised new biotechnological possibilities for the use of water-soluble melanin-like pigment naturally produced by B. weihenstephanensis as an alternative to commercial non-soluble pigment.

  2. Preparation of Thin Melanin-Type Films by Surface-Controlled Oxidation.

    PubMed

    Salomäki, Mikko; Tupala, Matti; Parviainen, Timo; Leiro, Jarkko; Karonen, Maarit; Lukkari, Jukka

    2016-04-26

    The preparation of thin melanin films suitable for applications is challenging. In this work, we present a new alternative approach to thin melanin-type films using oxidative multilayers prepared by the sequential layer-by-layer deposition of cerium(IV) and inorganic polyphosphate. The interfacial reaction between cerium(IV) in the multilayer and 5,6-dihydroxyindole (DHI) in the adjacent aqueous solution leads to the formation of a thin uniform film. The oxidation of DHI by cerium(IV) proceeds via known melanin intermediates. We have characterized the formed DHI-melanin films using scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), UV-vis spectroscopy, and spectroelectrochemistry. When a five-bilayer oxidative multilayer is used, the film is uniform with a thickness of ca. 10 nm. Its chemical composition, as determined using XPS, is typical for melanin. It is also redox active, and its oxidation occurs in two steps, which can be assigned to semiquinone and quinone formation within the indole structural motif. Oxidative multilayers can also oxidize dopamine, but the reaction stops at the dopamine quinone stage because of the limited amount of the multilayer-based oxidizing agent. However, dopamine oxidation by Ce(IV) was studied also in solution by UV-vis spectroscopy and mass spectrometry in order to verify the reaction mechanism and the final product. In solution, the oxidation of dopamine by cerium shows that the indole ring formation takes place already at low pH and that the mass spectrum of the final product is practically identical with that of commercial melanin. Therefore, layer-by-layer formed oxidative multilayers can be used to deposit functional melanin-type thin films on arbitrary substrates by a surface-controlled reaction.

  3. Melanin-Covered Nanoparticles for Protection of Bone Marrow During Radiation Therapy of Cancer

    SciTech Connect

    Schweitzer, Andrew D.; Revskaya, Ekaterina; Chu, Peter; Pazo, Valeria; Friedman, Matthew; Nosanchuk, Joshua D.; Cahill, Sean; Frases, Susana; Casadevall, Arturo; Dadachova, Ekaterina

    2010-12-01

    Purpose: Protection of bone marrow against radiotoxicity during radioimmunotherapy and in some cases external beam radiation therapy such as hemi-body irradiation would permit administration of significantly higher doses to tumors, resulting in increased efficacy and safety of treatment. Melanin, a naturally occurring pigment, possesses radioprotective properties. We hypothesized that melanin, which is insoluble, could be delivered to the bone marrow by intravenously administrated melanin-covered nanoparticles (MNs) because of the human body's 'self-sieving' ability, protecting it against ionizing radiation. Methods and Materials: The synthesis of MNs was performed via enzymatic polymerization of 3,4-dihydroxyphenylalanine and/or 5-S-cysteinyl-3,4-dihydroxyphenylalanine on the surface of 20-nm plain silica nanoparticles. The biodistribution of radiolabeled MNs in mice was done at 3 and 24 h. Healthy CD-1 mice (Charles River Laboratories International, Inc., Wilmington, MA) or melanoma tumor-bearing nude mice were given MNs intravenously, 50 mg/kg of body weight, 3 h before either whole-body exposure to 125 cGy or treatment with 1 mCi of {sup 188}Re-labeled 6D2 melanin-binding antibody. Results: Polymerization of melanin precursors on the surface of silica nanoparticles resulted in formation of a 15-nm-thick melanin layer as confirmed by light scattering, transmission electron microscopy, and immunofluorescence. The biodistribution after intravenous administration showed than MN uptake in bone marrow was 0.3% and 0.2% of injected dose per gram at 3 and 24 h, respectively, whereas pre-injection with pluronic acid increased the uptake to 6% and 3% of injected dose per gram, respectively. Systemic MN administration reduced hematologic toxicity in mice treated with external radiation or radioimmunotherapy, whereas no tumor protection by MNs was observed. Conclusions: MNs or similar structures provide a novel approach to protection of bone marrow from ionizing radiation

  4. Melanin-Like Pigment Synthesis by Soil Bacillus weihenstephanensis Isolates from Northeastern Poland

    PubMed Central

    Drewnowska, Justyna M.; Zambrzycka, Monika; Kalska-Szostko, Beata; Fiedoruk, Krzysztof; Swiecicka, Izabela

    2015-01-01

    Although melanin is known for protecting living organisms from harmful physical and chemical factors, its synthesis is rarely observed among endospore-forming Bacillus cereus sensu lato. Here, for the first time, we reported that psychrotolerant Bacillus weihenstephanensis from Northeastern Poland can produce melanin-like pigment. We assessed physicochemical properties of the pigment and the mechanism of its synthesis in relation to B. weihenstephanensis genotypic and phenotypic characteristics. Electron paramagnetic resonance (EPR) spectroscopy displayed a stable free radical signal of the pigment from environmental isolates which are consistent with the commercial melanin. Fourier transform infrared spectroscopy (FT-IR) and physicochemical tests indicated the phenolic character of the pigment. Several biochemical tests showed that melanin-like pigment synthesis by B. weihenstephanensis was associated with laccase activity. The presence of the gene encoding laccase was confirmed by the next generation whole genome sequencing of one B. weihenstephanensis strain. Biochemical (API 20E and 50CHB tests) and genetic (Multi-locus Sequence Typing, 16S rRNA sequencing, and Pulsed-Field Gel Electrophoresis) characterization of the isolates revealed their close relation to the psychrotrophic B. weihenstephanensis DSMZ 11821 reference strain. The ability to synthesize melanin-like pigment by soil B. weihenstephanensis isolates and their psychrotrophic character seemed to be a local adaptation to a specific niche. Detailed genetic and biochemical analyses of melanin-positive environmental B. weihenstephanensis strains shed some light on the evolution and ecological adaptation of these bacteria. Moreover, our study raised new biotechnological possibilities for the use of water-soluble melanin-like pigment naturally produced by B. weihenstephanensis as an alternative to commercial non-soluble pigment. PMID:25909751

  5. Purification and characterization of a melanin biodegradation enzyme from Geotrichum sp.

    PubMed

    Kim, B S; Blaghen, M; Hong, H-S; Lee, K-M

    2016-12-01

    Melanin is a black or brown phenolic polymer present mainly in skin and hair. Although melanin can be degraded by some microbial species, the melanin degradation capacity of Geotrichum sp. is unknown. The aim of this study was to characterize a melanin biodegradation enzyme from Geotrichum sp. In this study, we assessed the melanin degradation activity of Geotrichum sp. in comparison with the major melanin-degrading enzymes, manganese-dependent peroxidase (MnP), manganese-independent peroxidase, lignin peroxidase and laccase. Furthermore, the effect of several carbohydrates on melanin degradation by Geotrichum sp. was determined. The MnP enzyme was purified using ammonium sulphate precipitation and Sephadex G-200 column chromatography, and then the conditions for optimal enzymatic activity were determined by adjusting the pH, temperature and Tween-80 concentration. Compared with extracellular ligninolytic enzymes of Geotrichum sp., MnP had the highest ligninolytic enzyme activity; and the highest enzymatic activity was observed in the presence of glucose. The final purified MnP enzyme exhibited 6 U mL(-1) activity and had a molecular weight of 54.2 kDa. The enzymatic activity was highest at pH 4.5 and 25-35°C in the absence of Tween-80. These results indicate the potential of MnP purified from Geotrichum sp. as a skin-lightening agent in the cosmetic industry. © 2016 Society of Cosmetic Scientists and the Société Française de Cosmétologie.

  6. Redox buffering by melanin and Fe(II) in Cryptococcus neoformans.

    PubMed Central

    Jacobson, E S; Hong, J D

    1997-01-01

    Melanin is a fungal extracellular redox buffer which, in principle, can neutralize antimicrobial oxidants generated by immunologic effector cells, but its source of reducing equivalents is not known. We wondered whether Fe(II) generated by the external ferric reductase of fungi might have the physiologic function of reducing fungal melanin and thereby promoting pathogenesis. We observed that exposure of a melanin film electrode to reductants decreased the open-circuit potential (OCP) and reduced the area of a cyclic voltammetric reduction wave whereas exposure to oxidants produced the opposite effects. Exposure to 10, 100, 1,000 or 10,000 microM Fe(II) decreased the OCP of melanin by 0.015, 0.038, 0.100, and 0.120 V, respectively, relative to a silver-silver chloride standard, and decreased the area of the cyclic voltammetric reduction wave by 27, 35, 50, and 83%, respectively. Moreover, exposure to Fe(II) increased the buffering capacity by 44%, while exposure to millimolar dithionite did not increase the buffering capacity. The ratio of the amount of bound iron to the amount of the incremental increase in the following oxidation wave was approximately 1.0, suggesting that bound iron participates in buffering. Light absorption by melanin suspensions was decreased 14% by treatment with Fe(II), consistent with reduction of melanin. Light absorption by suspensions of melanized Cryptococcus neoformans was decreased 1.3% by treatment with Fe(II) (P < 0.05). Cultures of C. neoformans generated between 2 and 160 microM Fe(II) in culture supernatant, depending upon the strain and the conditions [the higher values were achieved by a constitutive ferric reductase mutant in high concentrations of Fe(III)]. We infer that Fe(II) can reduce melanin under physiologic conditions; moreover, it binds to melanin and cooperatively increases redox buffering. The data support a model for physiologic redox cycling of fungal melanin, whereby electrons exported by the yeast to form

  7. Interactions between Melanin Enzymes and Their Atypical Recruitment to the Secretory Pathway by Palmitoylation.

    PubMed

    Upadhyay, Srijana; Xu, Xinping; Lin, Xiaorong

    2016-11-22

    Melanins are biopolymers that confer coloration and protection to the host organism against biotic or abiotic insults. The level of protection offered by melanin depends on its biosynthesis and its subcellular localization. Previously, we discovered that Aspergillus fumigatus compartmentalizes melanization in endosomes by recruiting all melanin enzymes to the secretory pathway. Surprisingly, although two laccases involved in the late steps of melanization are conventional secretory proteins, the four enzymes involved in the early steps of melanization lack a signal peptide or a transmembrane domain and are thus considered "atypical" secretory proteins. In this work, we found interactions among melanin enzymes and all melanin enzymes formed protein complexes. Surprisingly, the formation of protein complexes by melanin enzymes was not critical for their trafficking to the endosomal system. By palmitoylation profiling and biochemical analyses, we discovered that all four early melanin enzymes were strongly palmitoylated during conidiation. However, only the polyketide synthase (PKS) Alb1 was strongly palmitoylated during both vegetative hyphal growth and conidiation when constitutively expressed alone. This posttranslational lipid modification correlates the endosomal localization of all early melanin enzymes. Intriguingly, bioinformatic analyses predict that palmitoylation is a common mechanism for potential membrane association of polyketide synthases (PKSs) and nonribosomal peptide synthetases (NRPSs) in A. fumigatus Our findings indicate that protein-protein interactions facilitate melanization by metabolic channeling, while posttranslational lipid modifications help recruit the atypical enzymes to the secretory pathway, which is critical for compartmentalization of secondary metabolism. Subcellular compartmentalization is increasingly recognized as an important aspect of fungal secondary metabolism. It facilitates sequential enzymatic reactions, provides

  8. Evolutionary shifts in the melanin-based color system of birds.

    PubMed

    Eliason, Chad M; Shawkey, Matthew D; Clarke, Julia A

    2016-02-01

    Melanin pigments contained in organelles (melanosomes) impart earthy colors to feathers. Such melanin-based colors are distributed across birds and thought to be the ancestral color-producing mechanism in birds. However, we have had limited data on melanin-based color and melanosome diversity in Palaeognathae, which includes the flighted tinamous and large-bodied, flightless ratites and is the sister taxon to all other extant birds. Here, we use scanning electron microscopy and spectrophotometry to assess melanosome morphology and quantify reflected color for 19 species within this clade. We find that brown colors in ratites are uniquely associated with elongated melanosomes nearly identical in shape to those associated with black colors. Melanosome and color diversity in large-bodied ratites is limited relative to other birds (including flightless penguins) and smaller bodied basal maniraptoran dinosaur outgroups of Aves, whereas tinamous show a wider range of melanosome forms similar to neognaths. The repeated occurrence of novel melanosome forms in the nonmonophyletic ratites suggests that melanin-based color tracks changes in body size, physiology, or other life history traits associated with flight loss, but not feather morphology. We further anticipate these findings will be useful for future color reconstructions in extinct species, as variation in melanosome shape may potentially be linked to a more nuanced palette of melanin-based colors.

  9. Aspergillus Cell Wall Melanin Blocks LC3-Associated Phagocytosis to Promote Pathogenicity.

    PubMed

    Akoumianaki, Tonia; Kyrmizi, Irene; Valsecchi, Isabel; Gresnigt, Mark S; Samonis, George; Drakos, Elias; Boumpas, Dimitrios; Muszkieta, Laetitia; Prevost, Marie-Christine; Kontoyiannis, Dimitrios P; Chavakis, Triantafyllos; Netea, Mihai G; van de Veerdonk, Frank L; Brakhage, Axel A; El-Benna, Jamel; Beauvais, Anne; Latge, Jean-Paul; Chamilos, Georgios

    2016-01-13

    Concealing pathogen-associated molecular patterns (PAMPs) is a principal strategy used by fungi to avoid immune recognition. Surface exposure of PAMPs during germination can leave the pathogen vulnerable. Accordingly, β-glucan surface exposure during Aspergillus fumigatus germination activates an Atg5-dependent autophagy pathway termed LC3-associated phagocytosis (LAP), which promotes fungal killing. We found that LAP activation also requires the genetic, biochemical or biological (germination) removal of A. fumigatus cell wall melanin. The attenuated virulence of melanin-deficient A. fumigatus is restored in Atg5-deficient macrophages and in mice upon conditional inactivation of Atg5 in hematopoietic cells. Mechanistically, Aspergillus melanin inhibits NADPH oxidase-dependent activation of LAP by excluding the p22phox subunit from the phagosome. Thus, two events that occur concomitantly during germination of airborne fungi, surface exposure of PAMPs and melanin removal, are necessary for LAP activation and fungal killing. LAP blockade is a general property of melanin pigments, a finding with broad physiological implications.

  10. Role of GTP-CHI links PAH and TH in melanin synthesis in silkworm, Bombyx mori.

    PubMed

    Chen, Ping; Wang, Jiying; Li, Haiyin; Li, Yan; Chen, Peng; Li, Tian; Chen, Xi; Xiao, Junjie; Zhang, Liang

    2015-08-10

    In insects, pigment patterns are formed by melanin, ommochromes, and pteridines. Here, the effects of pteridine synthesis on melanin formation were studied using 4th instar larvae of a wild-type silkworm strain, dazao (Bombyx mori), with normal color and markings. Results from injected larvae and in vitro integument culture indicated that decreased activity of guanosine triphosphate cyclohydrolase I (GTP-CH I, a rate-limiting enzyme for pteridine synthesis), lowers BH4 (6R-l-erythro-5,6,7,8-tetrahydrobiopterin, a production correlated with GTP-CH I activity) levels and eliminates markings and coloration. The conversion of phenylalanine and tyrosine to melanin was prevented when GTP-CH I was inhibited. When BH4 was added, phenylalanine was converted to tyrosine, and the tyrosine concentration increased. Tyrosine was then converted to melanin to create normal markings and coloration. Decreasing GTP-CH I activity did not affect L-DOPA (3,4-l-dihydroxyphenylalanine). GTP-CH I affected melanin synthesis by generating the BH4 used in two key reaction steps: (1) conversion of phenylalanine to tyrosine by PAH (phenylalanine hydroxylase) and (2) conversion of tyrosine to L-DOPA by TH (tyrosine hydroxylase). Expression profiles of BmGTPCH Ia, BmGTPCH Ib, BmTH, and BmPAH in the integument were consistent with the current findings.

  11. Melanocyte biology and function with reference to oral melanin hyperpigmentation in HIV-seropositive subjects.

    PubMed

    Feller, Liviu; Chandran, Rakesh; Kramer, Beverley; Khammissa, Razia A G; Altini, Mario; Lemmer, Johan

    2014-09-01

    The color of normal skin and of oral mucosa is not determined by the number of melanocytes in the epithelium but rather by their melanogenic activity. Pigmented biopolymers or melanins are synthesized in melanosomes. Tyrosinase is the critical enzyme in the biosynthesis of both brown/black eumelanin and yellow/red pheomelanin. The number of the melanosomes within the melanocytes, the type of melanin within the melanosomes, and the efficacy of the transfer of melanosomes from the melanocytes to the neighboring keratinocytes all play an important role in tissue pigmentation. Melanin production is regulated by locally produced factors including proopiomelanocortin and its derivative peptides, particularly alpha-melanocyte-stimulating hormone (α-MSH), melanocortin 1 receptor (MC1R), adrenergic and cholinergic agents, growth factors, cytokines, and nitric oxide. Both eumelanin and pheomelanin can be produced by the same melanocytes, and the proportion of the two melanin types is influenced by the degree of functional activity of the α-MSH/MC1R intracellular pathway. The cause of HIV oral melanosis is not fully understood but may be associated with HIV-induced cytokine dysregulation, with the medications commonly prescribed to HIV-seropositive persons, and with adrenocortical dysfunction, which is not uncommon in HIV-seropositive subjects with AIDS. The purpose of this article is to discuss some aspects of melanocyte biology and HIV-associated oral melanin hyperpigmentation.

  12. Localization of melanin in conidia of Alternaria alternata using phage display antibodies.

    PubMed

    Carzaniga, Raffaella; Fiocco, Daniela; Bowyer, Paul; O'Connell, Richard J

    2002-03-01

    Melanins derived from 1,8-dihydroxynaphthalene (DHN) are important for the pathogenicity and survival of fungi causing disease in both plants and animals. However, precise information on their location within fungal cell walls is lacking. To obtain antibodies for the immunocytochemical localization of melanin, 83 phage antibodies binding to 1,8-DHN were selected from a naive semisynthetic single-chain Fv (scFv) phage display library. Sequence analysis of the heavy chain binding domains of 17 antibodies showed a high frequency of positively charged amino acids. One antibody, designated M1, was characterized in detail. M1 bound specifically to 1,8-DHN in competitive inhibition enzyme-linked immunosorbent assays, showing no cross-reaction with nine structurally related phenolic compounds. Epitope recognition required two hydroxyl groups in a 1,8 configuration. M1 also bound to naturally occurring melanin isolated from mycelia of Alternaria alternata, suggesting that epitopes remain accessible in polymerized melanin. Transmission electron microscopy-immunogold labeling, using M1 in the form of soluble scFv fragments, showed that melanin was located in the septa and outer (primary) walls of wild-type A. alternata conidia, but not those of an albino mutant, AKT88-1. The M1 antibody provides a new tool for detecting melanized pathogens in plant and animal tissues and for precisely mapping the distribution of the polymer within spores, appressoria, and hyphae.

  13. Microneedling dilates the follicular infundibulum and increases transfollicular absorption of liposomal sepia melanin.

    PubMed

    Serrano, Gabriel; Almudéver, Patricia; Serrano, Juan M; Cortijo, Julio; Faus, Carmen; Reyes, Magda; Expósito, Inmaculada; Torrens, Ana; Millán, Fernando

    2015-01-01

    Encapsulation of chemicals in liposomes and microneedling are currently used techniques to enhance the penetration of several substances through skin and hair. In this study, we apply a liposomal melanin-fluorescein compound to an ex vivo model of human skin, using a new electrical microneedling device (Nanopore turbo roller). The product was applied by hand massage (A) or with the assistance of the electrical roller for 2 minutes (B). An additional test was performed free of product and with only the E-roller (C). Histological changes and product absorption were evaluated by optical and fluorescent microscopy 60 and 90 minutes after the treatment. Site B showed larger deposits of melanin-fluorescein at superficial and deep levels of hair structures in comparison to site A. Light, epidermal deposits of the melanin-fluorescein complex were also observed. Sites B and C showed a significant widening (47%) of the follicular infundibulum which could explain the increased penetration of the formulation. Microneedling also removed the scales and sebum residues in the neighborhood of the infundibulum. Targeting hair follicles with melanin may be useful to dye poorly pigmented hairs, improving laser hair removal. The procedure accelerates the delivery of melanin into hair structures allowing an even absorption, larger pigment deposits, and deeper penetration of the formulation into the hair.

  14. Polarization sensitive optical coherence tomography of melanin provides intrinsic contrast based on depolarization

    PubMed Central

    Baumann, Bernhard; Baumann, Stefan O.; Konegger, Thomas; Pircher, Michael; Götzinger, Erich; Schlanitz, Ferdinand; Schütze, Christopher; Sattmann, Harald; Litschauer, Marco; Schmidt-Erfurth, Ursula; Hitzenberger, Christoph K.

    2012-01-01

    Polarization sensitive optical coherence tomography (PS-OCT) is a functional extension of OCT. In addition to imaging based on tissue reflectivity, PS-OCT also enables depth-resolved mapping of sample polarization properties such as phase-retardation, birefringent axis orientation, Stokes vectors, and degree of polarization uniformity (DOPU). In this study, PS-OCT was used to investigate the polarization properties of melanin. In-vitro measurements in samples with varying melanin concentrations revealed polarization scrambling, i.e. depolarization of backscattered light. Polarization scrambling in the PS-OCT images was more pronounced for higher melanin concentrations and correlated with the concentration of the melanin granules in the phantoms. Moreover, in-vivo PS-OCT was performed in the retinas of normal subjects and individuals with albinism. Unlike in the normal eye, polarization scrambling in the retinal pigment epithelium (RPE) was less pronounced or even not observable in PS-OCT images of albinos. These results indicate that the depolarizing appearance of pigmented structures like, for instance, the RPE is likely to be caused by the melanin granules contained in these cells. PMID:22808437

  15. Melanin pigmentation gives rise to black spots on the wings of the silkworm Bombyx mori.

    PubMed

    Ito, Katsuhiko; Yoshikawa, Manabu; Fujii, Takeshi; Tabunoki, Hiroko; Yokoyama, Takeshi

    2016-01-01

    Several mutants of the silkworm Bombyx mori show body color variation at the larval and adult stages. The Wild wing spot (Ws) mutant exhibits a phenotype in which the moth has a spot on the apex of the forewing. In this study, we investigated this trait to elucidate the molecular mechanism underlying the color pattern. Microscopy of the black spot of Ws mutants showed that the pigment emerges in the scales of the wing, and accumulation of the pigment becomes strong just before eclosion. We next examined the relationship between the black spot of the Ws mutant and melanin. The spectrophotometry using alkaline extracts from the black spot in the wing showed the highest absorption intensity at 405nm, which is the absorbance wavelength of melanin. Moreover, inhibition assays for enzymes implicated in melanin synthesis using 3-iodo-l-tyrosine (a tyrosine hydroxylase inhibitor) and L-α-methyl-DOPA (a dopa decarboxylase inhibitor) revealed that treatment with each inhibitor disrupted the pigmentation of the wing of the Ws mutant. On the basis of these results, we analyzed the expression pattern of five genes involved in melanin formation, and found that the expression levels of yellow and laccase2 were increased just before pigmentation, whereas those of DDC, tan, and TH were increased when the apex of the wing turned black. These results showed that melanin pigmentation gives rise to the black spot on the wing. Copyright © 2016 Elsevier Ltd. All rights reserved.

  16. Interference of melanin in the susceptibility profile of Sporothrix species to amphotericin B.

    PubMed

    Mario, Débora Alves Nunes; Santos, Roberto Christ Vianna; Denardi, Laura Bedin; Vaucher, Rodrigo de Almeida; Santurio, Janio Morais; Alves, Sydney Hartz

    2016-01-01

    The presence of melanin in the fungal cell is a major virulence factor of the genus Sporothrix since it protects the fungal cells against the defense systems. The present study aimed to investigate the interference of melanin in the susceptibility of Sporothrix brasiliensis and Sporothrix schenckii sensu stricto to amphotericin B and itraconazole, drugs recommended as therapy for disseminated and subcutaneous sporotrichosis, respectively. Yeast cells were cultivated in minimal medium with or without l-DOPA in order to induce the production of melanin. Microdilution and killing assay methods were used to determine the antifungal activity against yeast cells with different amounts of melanin. The killing assay showed that melanization protected isolates within the S. schenckii complex from amphotericin B, particularly in the lower concentrations tested. Studies combining amphotericin B and inhibitors of melanin are required in order to avoid this effect. Copyright © 2014 Asociación Española de Micología. Published by Elsevier Espana. All rights reserved.

  17. Coumestrol Down-Regulates Melanin Production in Melan-a Murine Melanocytes through Degradation of Tyrosinase.

    PubMed

    Hwang, Jeong Ah; Park, Nok Hyun; Na, Yong Joo; Lee, Hae Kwang; Lee, John Hwan; Kim, Yong Jin; Lee, Chang Seok

    2017-01-01

    Pigmentation reflects skin darkening caused by melanin production, but excessive melanin synthesis may cause problems, such as melasma, solar lentigo, dark spots, and freckles. Considerable effort has been devoted to alleviating these undesired symptoms through the development of safe and effective depigmenting agents. Coumestrol, a plant-derived natural isoflavone with an estrogen-like structure and actions, is known to have anti-aging ability, but its potential depigmenting efficacy has not been evaluated. In the present study, we investigated the effects of coumestrol on melanin synthesis in normal melan-a murine melanocytes. Coumestrol significantly reduced melanin synthesis in a concentration-dependent manner up to a concentration of 25 µM without causing cytotoxicity. It also brightened tissue in an artificial skin model (MelanoDerm) that incorporates both human keratinocytes and melanocytes. Interestingly, although coumestrol did not inhibit tyrosinase activity or transcript level in melan-a cells, it clearly decreased the expression level of tyrosinase protein at a concentration of 25 µM. This coumestrol-induced reduction in tyrosinase protein levels was prevented by pretreatment with the proteasome inhibitor MG-132 or the lysosomal proteolysis inhibitor chloroquine. Collectively, our findings indicate that coumestrol exerts an inhibitory effect on melanin synthesis in melan-a cells, at least in part, through degradation of tyrosinase. These findings suggest that coumestrol is a good candidate for use in depigmentary reagents from a cosmetic and clinical perspective.

  18. Separating melanin from hemodynamics in nevi using multimode hyperspectral dermoscopy and spatial frequency domain spectroscopy

    NASA Astrophysics Data System (ADS)

    Vasefi, Fartash; MacKinnon, Nicholas; Saager, Rolf; Kelly, Kristen M.; Maly, Tyler; Booth, Nicholas; Durkin, Anthony J.; Farkas, Daniel L.

    2016-11-01

    Changes in the pattern and distribution of both melanocytes (pigment producing) and vasculature (hemoglobin containing) are important in distinguishing melanocytic proliferations. The ability to accurately measure melanin distribution at different depths and to distinguish it from hemoglobin is clearly important when assessing pigmented lesions (benign versus malignant). We have developed a multimode hyperspectral dermoscope (SkinSpect™) able to more accurately image both melanin and hemoglobin distribution in skin. SkinSpect uses both hyperspectral and polarization-sensitive measurements. SkinSpect's higher accuracy has been obtained by correcting for the effect of melanin absorption on hemoglobin absorption in measurements of melanocytic nevi. In vivo human skin pigmented nevi (N=20) were evaluated with the SkinSpect, and measured melanin and hemoglobin concentrations were compared with spatial frequency domain spectroscopy (SFDS) measurements. We confirm that both systems show low correlation of hemoglobin concentrations with regions containing different melanin concentrations (R=0.13 for SFDS, R=0.07 for SkinSpect).

  19. Generation and suppression of singlet oxygen in hair by photosensitization of melanin.

    PubMed

    Chiarelli-Neto, Orlando; Pavani, Christiane; Ferreira, Alan S; Uchoa, Adjaci F; Severino, Divinomar; Baptista, Maurício S

    2011-09-15

    We have studied the spectroscopic properties of hair (white, blond, red, brown, and black) under illumination with visible light, giving special emphasis to the photoinduced generation of singlet oxygen ((1)O(2)). Irradiation of hair shafts (λ(ex)>400 nm) changed their properties by degrading the melanin. Formation of C3 hydroperoxides in the melanin indol groups was proven by (1)H NMR. After 532-nm excitation, all hair shafts presented the characteristic (1)O(2) emission (λ(em)=1270 nm), whose intensity varied inversely with the melanin content. (1)O(2) lifetime was also shown to vary with hair type, being five times shorter in black hair than in blond hair, indicating the role of melanin as a (1)O(2) suppressor. Lifetime ranged from tenths of a nanosecond to a few microseconds, which is much shorter than the lifetime expected for (1)O(2) in the solvents in which the hair shafts were suspended, indicating that (1)O(2) is generated and suppressed inside the hair structure. Both eumelanin and pheomelanin were shown to produce and to suppress (1)O(2), with similar efficiencies. The higher amount of (1)O(2) generated in blond hair and its longer lifetime is compatible with the stronger damage that light exposure causes in blond hair. We propose a model to explain the formation and suppression of (1)O(2) in hair by photosensitization of melanin with visible light and the deleterious effects that an excess of visible light may cause in hair and skin.

  20. Two-photon excited fluorescence lifetime imaging and spectroscopy of melanins in vitro and in vivo

    NASA Astrophysics Data System (ADS)

    Krasieva, Tatiana B.; Stringari, Chiara; Liu, Feng; Sun, Chung-Ho; Kong, Yu; Balu, Mihaela; Meyskens, Frank L.; Gratton, Enrico; Tromberg, Bruce J.

    2013-03-01

    Changes in the amounts of cellular eumelanin and pheomelanin have been associated with carcinogenesis. The goal of this work is to develop methods based on two-photon-excited-fluorescence (TPEF) for measuring relative concentrations of these compounds. We acquire TPEF emission spectra (λex=1000 nm) of melanin in vitro from melanoma cells, hair specimens, and in vivo from healthy volunteers. We find that the pheomelanin emission peaks at approximately 615 to 625 nm and eumelanin exhibits a broad maximum at 640 to 680 nm. Based on these data we define an optical melanin index (OMI) as the ratio of fluorescence intensities at 645 and 615 nm. The measured OMI for the MNT-1 melanoma cell line is 1.6±0.22 while the Mc1R gene knockdown lines MNT-46 and MNT-62 show substantially greater pheomelanin production (OMI=0.5±0.05 and 0.17±0.03, respectively). The measured values are in good agreement with chemistry-based melanin extraction methods. In order to better separate melanin fluorescence from other intrinsic fluorophores, we perform fluorescence lifetime imaging microscopy of in vitro specimens. The relative concentrations of keratin, eumelanin, and pheomelanin components are resolved using a phasor approach for analyzing lifetime data. Our results suggest that a noninvasive TPEF index based on spectra and lifetime could potentially be used for rapid melanin ratio characterization both in vitro and in vivo.

  1. Condition-dependent expression of melanin-based coloration in the Eurasian kestrel

    NASA Astrophysics Data System (ADS)

    Piault, Romain; van den Brink, Valentijn; Roulin, Alexandre

    2012-05-01

    Melanin is the most common pigment in animal integuments and is responsible for some of the most striking ornaments. A central tenet of sexual selection theory states that melanin-based traits can signal absolute individual quality in any environment only if their expression is condition-dependent. Significant costs imposed by an ornament would ensure that only the highest quality individuals display the most exaggerated forms of the signal. Firm evidence that melanin-based traits can be condition-dependent is still rare in birds. In an experimental test of this central assumption, we report condition-dependent expression of a melanin-based trait in the Eurasian kestrel ( Falco tinnunculus). We manipulated nestling body condition by reducing or increasing the number of nestlings soon after hatching. A few days before fledging, we measured the width of sub-terminal black bands on the tail feathers. Compared to nestlings from enlarged broods, individuals raised in reduced broods were in better condition and thereby developed larger sub-terminal bands. Furthermore, in 2 years, first-born nestlings also developed larger sub-terminal bands than their younger siblings that are in poorer condition. This demonstrates that expression of melanin-based traits can be condition-dependent.

  2. Melanin-Concentrating Hormone: A New Sleep Factor?

    PubMed Central

    Torterolo, Pablo; Lagos, Patricia; Monti, Jaime M.

    2011-01-01

    Neurons containing the neuropeptide melanin-concentrating hormone (MCH) are mainly located in the lateral hypothalamus and the incerto-hypothalamic area, and have widespread projections throughout the brain. While the biological functions of this neuropeptide are exerted in humans through two metabotropic receptors, the MCHR1 and MCHR2, only the MCHR1 is present in rodents. Recently, it has been shown that the MCHergic system is involved in the control of sleep. We can summarize the experimental findings as follows: (1) The areas related to the control of sleep and wakefulness have a high density of MCHergic fibers and receptors. (2) MCHergic neurons are active during sleep, especially during rapid eye movement (REM) sleep. (3) MCH knockout mice have less REM sleep, notably under conditions of negative energy balance. Animals with genetically inactivated MCHR1 also exhibit altered vigilance state architecture and sleep homeostasis. (4) Systemically administered MCHR1 antagonists reduce sleep. (5) Intraventricular microinjection of MCH increases both slow wave sleep (SWS) and REM sleep; however, the increment in REM sleep is more pronounced. (6) Microinjection of MCH into the dorsal raphe nucleus increases REM sleep time. REM seep is inhibited by immunoneutralization of MCH within this nucleus. (7) Microinjection of MCH in the nucleus pontis oralis of the cat enhances REM sleep time and reduces REM sleep latency. All these data strongly suggest that MCH has a potent role in the promotion of sleep. Although both SWS and REM sleep are facilitated by MCH, REM sleep seems to be more sensitive to MCH modulation. PMID:21516258

  3. Anti-inflammatory and immunomodulating properties of grape melanin. Inhibitory effects on paw edema and adjuvant induced disease.

    PubMed

    Avramidis, N; Kourounakis, A; Hadjipetrou, L; Senchuk, V

    1998-07-01

    Natural or synthetic melanin (CAS 8049-97-6) is a high molecular weight heteropolymer, product of the enzyme tyrosinase, found to possess radical scavenging and antioxidant functions. It was of interest, therefore, to study in detail the possible anti-inflammatory and/or immunosuppressive properties of a melanin isolated from grapes. The inhibitory effect of melanin on carrageenin-induced edema, as well as on edemas produced by other phlogistics, was remarkable suggesting that melanin interferes with the prostaglandin as well as the leukotriene and/or complement system mediated inflammation. Grape melanin showed potent inhibitory effect on adjuvant induced disease (AID) in rat, suppressing significantly the primary inflammation and almost totally the secondary lesions of arthritis. Melanin under the present experimental conditions not only strongly inhibited the in vitro lipid peroxidation of rat liver microsomal membranes, but furthermore protected the in vivo hepatic peroxidation occurring in AID rats, demonstrating its antioxidant and cytoprotective properties. The serum proinflammatory cytokines IL-1, IL-6 and TNF-a and the serum globulin fraction were elevated in AID rats, parameters which were more or less normalised by melanin treatment in contrast to the reduced serum levels of IL-2 which were not affected. Similarly to other lipoxygenase inhibitors and hydroxyl radical scavenger NSAIDs, melanin treatment did not affect IL-1 neither increased the splenic mitogenic responses, unlike the classical cyclooxygenase inhibitory NSAIDs. The subpopulation Th1 (T4+ or T8+) of lymphocytes is mainly responsible for cellular immune responses and thus their possible inhibition by melanin could lead to suppression of the development of AID, a model for cell-mediated immunity. The effect of melanin on T-cells is exhibited by the reduced spleen mitogenic responses to a T-cell mitogen and the reduced serum levels of IL-2 of treated rats. In conclusion, grape melanin is an

  4. The Protective Role of Melanin Against UV Damage in Human Skin

    PubMed Central

    Brenner, Michaela; Hearing, Vincent J.

    2009-01-01

    Human skin is repeatedly exposed to ultraviolet radiation (UVR) that influences the function and survival of many cell types and is regarded as the main causative factor in the induction of skin cancer. It has been traditionally believed that skin pigmentation is the most important photoprotective factor, since melanin, besides functioning as a broadband UV absorbent, has antioxidant and radical scavenging properties. Besides, many epidemiological studies have shown a lower incidence for skin cancer in individuals with darker skin compared to those with fair skin. Skin pigmentation is of great cultural and cosmetic importance, yet the role of melanin in photoprotection is still controversial. This article outlines the major acute and chronic effects of UV radiation on human skin, the properties of melanin, the regulation of pigmentation and its effect on skin cancer prevention. PMID:18435612

  5. Quantitative photoacoustics to measure single cell melanin production and nanoparticle attachment

    NASA Astrophysics Data System (ADS)

    Bhattacharyya, Kiran; Eshein, Adam; Chandrasekhar, Anand; Viator, John A.

    2015-04-01

    Photoacoustics can be used as a label-free spectroscopic method of identifying pigmented proteins and characterizing their intracellular concentration over time in a single living cell. The authors use a microscopic laser irradiation system with a 5 ns, Q-switched laser focused onto single cells in order to collect photoacoustic responses of melanoma cells from the HS936 cell line and gold nanoparticle labeled breast cancer cells from the T47D cell line. The volume averaged intracellular concentration of melanin is found to range from 29-270 mM for single melanoma cells and the number of gold nanoparticles (AuNP) is shown to range from 850-5900 AuNPs/cell. Additionally, the melanin production response to UV-A light stimulus is measured in four melanoma cells to find a mass production rate of 5.7 pg of melanin every 15 min.

  6. Melanin-containing films: growth from dopamine solutions versus layer-by-layer deposition.

    PubMed

    Bernsmann, Falk; Ersen, Ovidiu; Voegel, Jean-Claude; Jan, Edward; Kotov, Nicholas A; Ball, Vincent

    2010-10-25

    Films formed by oxidation of dopamine are of interest for functionalisation of solid-liquid interfaces owing to their versatility. However, the ability to modulate the properties of such films, for example, permeability to ionic species and the absorption coefficient, is urgently needed. Indeed, melanin films produced by oxidation of dopamine absorb strongly over the whole UV/Vis part of the electromagnetic spectrum and are impermeable to anions even for a film thickness as low as a few nanometers. Herein we combine oxidation of dopamine to produce a solution containing dopamine-melanin particles and their alternating deposition with poly(diallyldimethylammonium chloride) to produce films which have nearly the same morphology as pure dopamine-melanin films but are less compact, more transparent and more permeable to ferrocyanide anions.

  7. Characterization of a Fungal Thioesterase Having Claisen Cyclase and Deacetylase Activities in Melanin Biosynthesis

    PubMed Central

    Vagstad, Anna L; Hill, Eric A; Labonte, Jason W; Townsend, Craig A

    2012-01-01

    Summary Melanins are a broad class of darkly-pigmented macromolecules formed by oxidative polymerization of phenolic monomers. In fungi, melanins are known virulence factors that contribute to pathogenicity. Their biosynthesis generally involves polymerization of 1,8-dihydroxynaphthalene via a 1,3,6,8- tetrahydroxynaphthalene (THN) precursor assembled by multidomain, nonreducing polyketide synthases. Multiple, convergent routes to THN have evolved in fungi. Parallel heptaketide and hexaketide pathways exist that utilize conventional C-terminal thioesterase/Claisen cyclase domains and separate side-chain deacylases. Here, in vitro characterization of Pks1 from Colletotrichum lagenarium establishes a true THN synthase with a bifunctional thioesterase (TE) catalyzing both cyclization and deacetylation of an enzyme-bound hexaketide substrate. Chimeric TE domains were generated by swapping lid regions of active sites between classes of melanin TEs to gain insight into this unprecedented catalysis of carbon–carbon bond making and breaking by an α/β-hydrolase fold enzyme. PMID:23261597

  8. Quantitative photoacoustics to measure single cell melanin production and nanoparticle attachment

    PubMed Central

    Bhattacharyya, Kiran; Eshein, Adam; Chandrasekhar, Anand; Viator, John A.

    2015-01-01

    Photoacoustics can be used as a label-free spectroscopic method of identifying pigmented proteins and characterizing their intracellular concentration over time in a single living cell. The authors use a microscopic laser irradiation system with a 5 ns, Q-switched laser focused onto single cells in order to collect photoacoustic responses of melanoma cells from the HS936 cell line and gold nanoparticle labeled breast cancer cells from the T47D cell line. The volume averaged intracellular concentration of melanin is found to range from 29–270mM for single melanoma cells and the number of gold nanoparticles (AuNP) is shown to range from 850–5900 AuNPs/cell. Additionally, the melanin production response to UV-A light stimulus is measured in four melanoma cells to find a mass production rate of 5.7 pg of melanin every 15 minutes. PMID:25803095

  9. Phenolic melanin precursors provide a rational approach to the design of antitumor agents for melanoma

    SciTech Connect

    Jimbow, K.; Miura, T.; Ito, S.; Ishikawa, K.

    1989-01-01

    A unique biological property of the melanocyte, melanin synthesis may permit a rational approach to design agents for better management of malignant melanoma. This in vivo and in vitro study examined the selective melanocytotoxicity and antimelanoma effects of phenolic compounds, cysteinylphenol (CP), cysteaminylphenol (CAP), and related compounds, and found (1) that both 4-S-CP and 4-S-CAP are melanin precursors, (2) that 4-S-CAP possesses a marked depigmenting potency with selective destruction of melanocytes in black follicles, and (3) a significant inhibition in the protein synthesis and tumor growth of B16 melanoma. Importantly, a whole body autoradiography indicated that these phenolic melanin precursors are selectively incorporated into melanoma tissues after i.p. administration.

  10. Innovative use of Mucuna monosperma (Wight) callus cultures for continuous production of melanin by using statistically optimized biotransformation medium.

    PubMed

    Inamdar, Shrirang; Joshi, Swati; Bapat, Vishwas; Jadhav, Jyoti

    2014-01-20

    Melanins are predominantly indolic polymers which are having extensive applications in cosmetics, agriculture and medicine. In the present study, optimization of nutritional parameters influencing melanin production by Mucuna monosperma callus cultures was attempted using the response surface methodology (RSM). Standardization of four factors was carried out using the Box-Behnken design. The optimized levels of factors predicted by the model include tyrosine 0.978gL(-1), pH 5.85, SDS 34.55mgL(-1)and copper sulphate 21.14mgL(-1) tyrosine, which resulted in highest melanin yield of 0.887gL(-1). The optimization of medium using RSM resulted in a 3.06-fold increase in the yield of melanin. The ANOVA analysis showed a significant R(2)-value (0.9995), model F-value (1917.72) and probability (0.0001), with insignificant lack of fit. Optimized medium was used in the laboratory scale column reactor for the continuous production of melanin. Uninterrupted flow column exhibited maximum melanin production rate of 250mgL(-1)h(-1) which is the highest value ever reported using plant as a biotransformation source. Melanin production was confirmed by spectrophotometric and chemical analysis. Thus, this study demonstrates the production of melanin by M. monosperma callus, using a laboratory scale column reactor.

  11. In vivo measurements of cutaneous melanin across spatial scales: using multiphoton microscopy and spatial frequency domain spectroscopy.

    PubMed

    Saager, Rolf B; Balu, Mihaela; Crosignani, Viera; Sharif, Ata; Durkin, Anthony J; Kelly, Kristen M; Tromberg, Bruce J

    2015-06-01

    The combined use of nonlinear optical microscopy and broadband reflectance techniques to assess melanin concentration and distribution thickness in vivo over the full range of Fitzpatrick skin types is presented. Twelve patients were measured using multiphoton microscopy (MPM) and spatial frequency domain spectroscopy (SFDS) on both dorsal forearm and volar arm, which are generally sun-exposed and non-sun-exposed areas, respectively. Both MPM and SFDS measured melanin volume fractions between (skin type I non-sun-exposed) and 20% (skin type VI sun exposed). MPM measured epidermal (anatomical) thickness values ~30-65 μm, while SFDS measured melanin distribution thickness based on diffuse optical path length. There was a strong correlation between melanin concentration and melanin distribution (epidermal) thickness measurements obtained using the two techniques. While SFDS does not have the ability to match the spatial resolution of MPM, this study demonstrates that melanin content as quantified using SFDS is linearly correlated with epidermal melanin as measured using MPM (R² = 0.8895). SFDS melanin distribution thickness is correlated to MPM values (R² = 0.8131). These techniques can be used individually and/or in combination to advance our understanding and guide therapies for pigmentation-related conditions as well as light-based treatments across a full range of skin types.

  12. In vivo measurements of cutaneous melanin across spatial scales: using multiphoton microscopy and spatial frequency domain spectroscopy

    NASA Astrophysics Data System (ADS)

    Saager, Rolf B.; Balu, Mihaela; Crosignani, Viera; Sharif, Ata; Durkin, Anthony J.; Kelly, Kristen M.; Tromberg, Bruce J.

    2015-06-01

    The combined use of nonlinear optical microscopy and broadband reflectance techniques to assess melanin concentration and distribution thickness in vivo over the full range of Fitzpatrick skin types is presented. Twelve patients were measured using multiphoton microscopy (MPM) and spatial frequency domain spectroscopy (SFDS) on both dorsal forearm and volar arm, which are generally sun-exposed and non-sun-exposed areas, respectively. Both MPM and SFDS measured melanin volume fractions between ˜5% (skin type I non-sun-exposed) and 20% (skin type VI sun exposed). MPM measured epidermal (anatomical) thickness values ˜30-65 μm, while SFDS measured melanin distribution thickness based on diffuse optical path length. There was a strong correlation between melanin concentration and melanin distribution (epidermal) thickness measurements obtained using the two techniques. While SFDS does not have the ability to match the spatial resolution of MPM, this study demonstrates that melanin content as quantified using SFDS is linearly correlated with epidermal melanin as measured using MPM (R2=0.8895). SFDS melanin distribution thickness is correlated to MPM values (R2=0.8131). These techniques can be used individually and/or in combination to advance our understanding and guide therapies for pigmentation-related conditions as well as light-based treatments across a full range of skin types.

  13. Diffuse Reflectance Spectroscopy Versus Mexameter(®) MX18 Measurements of Melanin and Erythema in an African Population.

    PubMed

    Wright, Caradee Y; Karsten, Aletta E; Wilkes, Marcus; Singh, Ann; du Plessis, Johan; Albers, Patricia N; Karsten, Petrus A

    2016-07-01

    Melanin provides protection against excess exposure to solar ultraviolet radiation (UVR) and related adverse health effects. Diffuse reflectance spectroscopy (DRS) can be used to calculate cutaneous melanin and erythema, but this is complex and has been mostly used for light-to-medium pigmented skin. Handheld reflectance spectrophotometers, such as the Mexameter(®) MX18, can also be used. We compared DRS-calculated melanin and erythema values with Mexameter melanin and erythema index values to understand how these techniques/measurements correlate in an African population of predominantly deeply pigmented skin. Five hundred and three participants comprised 68.5% self-identified Black African, 9.9% Indian/Asian, 18.4% White and 2.9% Colored. The majority of Black African (45%), Indian/Asian (34%) and Colored (53%) participants self-identified their skin as being "brown." Measured melanin levels increased with darker self-reported skin color. DRS-calculated and Mexameter melanin values demonstrated a positive correlation (Spearman rho = 0.87, P < 0.001). The results from both instruments showed erythema values were strongly correlated with their own melanin values. This finding is considered spurious and may result from the complexity of separating brown and red pigment when using narrowband reflectance techniques. Further work is needed to understand melanin, erythema and color in Black skin given sun-related health risks in vulnerable groups in Africa.

  14. Regulation of melanin biosynthesis via the dihydroxynaphthalene pathway is dependent on sexual development in the ascomycete Sordaria macrospora.

    PubMed

    Engh, Ines; Nowrousian, Minou; Kück, Ulrich

    2007-10-01

    The filamentous ascomycete Sordaria macrospora accumulates melanin during sexual development. The four melanin biosynthesis genes pks, teh, sdh and tih were isolated and their homology to genes involved in 1,8 dihydroxynaphthalene (DHN) melanin biosynthesis was shown. The presence of DHN melanin in S. macrospora was further confirmed by disrupting the pks gene encoding a putative polyketide synthase and by RNA interference-mediated silencing of the sdh gene encoding a putative scytalone dehydratase. Because melanin occurs in fruiting bodies that develop through several intermediate stages within 7 days of growth, a Northern analysis of a developmental time-course was conducted. These data revealed a time-dependent regulation of teh and sdh transcript levels. Comparing the transcriptional expression by real-time PCR of melanin biosynthesis genes in the wild type under conditions allowing or repressing sexual development, a significant downregulation during vegetative growth was detected. Quantitative real-time PCR and Northern blot analysis of melanin biosynthesis gene expression in different developmental mutants confirmed that melanin biosynthesis is linked to fruiting body development and is under the control of specific regulatory genes that participate in sexual differentiation.

  15. In vivo measurements of cutaneous melanin across spatial scales: using multiphoton microscopy and spatial frequency domain spectroscopy

    PubMed Central

    Saager, Rolf B.; Balu, Mihaela; Crosignani, Viera; Sharif, Ata; Durkin, Anthony J.; Kelly, Kristen M.; Tromberg, Bruce J.

    2015-01-01

    Abstract. The combined use of nonlinear optical microscopy and broadband reflectance techniques to assess melanin concentration and distribution thickness in vivo over the full range of Fitzpatrick skin types is presented. Twelve patients were measured using multiphoton microscopy (MPM) and spatial frequency domain spectroscopy (SFDS) on both dorsal forearm and volar arm, which are generally sun-exposed and non-sun-exposed areas, respectively. Both MPM and SFDS measured melanin volume fractions between ∼5% (skin type I non-sun-exposed) and 20% (skin type VI sun exposed). MPM measured epidermal (anatomical) thickness values ∼30–65  μm, while SFDS measured melanin distribution thickness based on diffuse optical path length. There was a strong correlation between melanin concentration and melanin distribution (epidermal) thickness measurements obtained using the two techniques. While SFDS does not have the ability to match the spatial resolution of MPM, this study demonstrates that melanin content as quantified using SFDS is linearly correlated with epidermal melanin as measured using MPM (R2=0.8895). SFDS melanin distribution thickness is correlated to MPM values (R2=0.8131). These techniques can be used individually and/or in combination to advance our understanding and guide therapies for pigmentation-related conditions as well as light-based treatments across a full range of skin types. PMID:26065839

  16. Condition-dependence, pleiotropy and the handicap principle of sexual selection in melanin-based colouration.

    PubMed

    Roulin, Alexandre

    2016-05-01

    The signalling function of melanin-based colouration is debated. Sexual selection theory states that ornaments should be costly to produce, maintain, wear or display to signal quality honestly to potential mates or competitors. An increasing number of studies supports the hypothesis that the degree of melanism covaries with aspects of body condition (e.g. body mass or immunity), which has contributed to change the initial perception that melanin-based colour ornaments entail no costs. Indeed, the expression of many (but not all) melanin-based colour traits is weakly sensitive to the environment but strongly heritable suggesting that these colour traits are relatively cheap to produce and maintain, thus raising the question of how such colour traits could signal quality honestly. Here I review the production, maintenance and wearing/displaying costs that can generate a correlation between melanin-based colouration and body condition, and consider other evolutionary mechanisms that can also lead to covariation between colour and body condition. Because genes controlling melanic traits can affect numerous phenotypic traits, pleiotropy could also explain a linkage between body condition and colouration. Pleiotropy may result in differently coloured individuals signalling different aspects of quality that are maintained by frequency-dependent selection or local adaptation. Colouration may therefore not signal absolute quality to potential mates or competitors (e.g. dark males may not achieve a higher fitness than pale males); otherwise genetic variation would be rapidly depleted by directional selection. As a consequence, selection on heritable melanin-based colouration may not always be directional, but mate choice may be conditional to environmental conditions (i.e. context-dependent sexual selection). Despite the interest of evolutionary biologists in the adaptive value of melanin-based colouration, its actual role in sexual selection is still poorly understood.

  17. Multivariate heredity of melanin-based coloration, body mass and immunity.

    PubMed

    Kim, S-Y; Fargallo, J A; Vergara, P; Martínez-Padilla, J

    2013-08-01

    The genetic covariation among different traits may cause the appearance of correlated response to selection on multivariate phenotypes. Genes responsible for the expression of melanin-based color traits are also involved in other important physiological functions such as immunity and metabolism by pleiotropy, suggesting the possibility of multivariate evolution. However, little is known about the relationship between melanin coloration and these functions at the additive genetic level in wild vertebrates. From a multivariate perspective, we simultaneously explored inheritance and selection of melanin coloration, body mass and phytohemagglutinin (PHA)-mediated immune response by using long-term data over an 18-year period collected in a wild population of the common kestrel Falco tinnunculus. Pedigree-based quantitative genetic analyses showed negative genetic covariance between melanin-based coloration and body mass in male adults and positive genetic covariance between body mass and PHA-mediated immune response in fledglings as predicted by pleiotropic effects of melanocortin receptor activity. Multiple selection analyses showed an increased fitness in male adults with intermediate phenotypic values for melanin color and body mass. In male fledglings, there was evidence for a disruptive selection on rump gray color, but a stabilizing selection on PHA-mediated immune response. Our results provide an insight into the evolution of multivariate traits genetically related with melanin-based coloration. The differences in multivariate inheritance and selection between male and female kestrels might have resulted in sexual dimorphism in size and color. When pleiotropic effects are present, coloration can evolve through a complex pathway involving correlated response to selection on multivariate traits.

  18. An Intracellular Antioxidant Determines the Expression of a Melanin-Based Signal in a Bird

    PubMed Central

    Galván, Ismael; Alonso-Alvarez, Carlos

    2008-01-01

    To understand how traits used in animal communication evolved and are maintained as honest signals, we need to understand the mechanisms that prevent cheating. It has been proposed that honest signaling is guaranteed by the costs associated with the signal expression. However, the nature of these costs is still under debate. Melanin-based signals are intriguing because their expression seems to be tightly controlled by genes and the resource involved (i.e. melanin) seems to be not limited. However, in vertebrates, low levels of a key intracellular antioxidant (i.e. glutathione) are needed to promote melanogenesis. We propose that melanin-based ornaments can signal the ability to cope with oxidative stress because those individuals with low enough levels of glutathione, such as those required for melanin production, should manage well the whole of the antioxidant machinery in order to maintain a certain oxidative status. We analysed the expression of a melanin-based signal: the well-known black stripe of the great tit (Parus major). Great tit nestlings were injected with a specific inhibitor of glutathione production (DL-buthionine-S,R-sulfoximine; BSO) throughout their development. BSO effectively decreased intracellular glutathione levels without apparent side effects on growth or body condition. Instead, treated nestlings developed black breast stripes 70–100% larger than controls. Moreover, treated nestlings also compensated the decrease in glutathione levels by increasing the levels of circulating antioxidants. Results indicate that melanin-based signals can be at least partially permeable to environmental influences such as those associated to oxidative stress. They also reveal a potential handicap associated to the expression of this kind of signals. Finally, although other contributing factors could have been present, our findings emphasize the role of oxidative stress in shaping the evolution of animal signals in general and, in particular, those produced

  19. Multivariate heredity of melanin-based coloration, body mass and immunity

    PubMed Central

    Kim, S-Y; Fargallo, J A; Vergara, P; Martínez-Padilla, J

    2013-01-01

    The genetic covariation among different traits may cause the appearance of correlated response to selection on multivariate phenotypes. Genes responsible for the expression of melanin-based color traits are also involved in other important physiological functions such as immunity and metabolism by pleiotropy, suggesting the possibility of multivariate evolution. However, little is known about the relationship between melanin coloration and these functions at the additive genetic level in wild vertebrates. From a multivariate perspective, we simultaneously explored inheritance and selection of melanin coloration, body mass and phytohemagglutinin (PHA)-mediated immune response by using long-term data over an 18-year period collected in a wild population of the common kestrel Falco tinnunculus. Pedigree-based quantitative genetic analyses showed negative genetic covariance between melanin-based coloration and body mass in male adults and positive genetic covariance between body mass and PHA-mediated immune response in fledglings as predicted by pleiotropic effects of melanocortin receptor activity. Multiple selection analyses showed an increased fitness in male adults with intermediate phenotypic values for melanin color and body mass. In male fledglings, there was evidence for a disruptive selection on rump gray color, but a stabilizing selection on PHA-mediated immune response. Our results provide an insight into the evolution of multivariate traits genetically related with melanin-based coloration. The differences in multivariate inheritance and selection between male and female kestrels might have resulted in sexual dimorphism in size and color. When pleiotropic effects are present, coloration can evolve through a complex pathway involving correlated response to selection on multivariate traits. PMID:23591519

  20. Electrochemical preparation and delivery of melanin-iron covered gold nanoparticles.

    PubMed

    Grumelli, Doris; Vericat, Carolina; Benítez, Guillermo; Ramallo-López, José M; Giovanetti, Lisandro; Requejo, Félix; Moreno, M Sergio; Orive, Alejandro González; Creus, Alberto Hernández; Salvarezza, Roberto C

    2009-02-02

    Attractive combination: Biopolymer-modified nanoparticles which combine magnetic properties with biocompatibility are prepared and delivered following a three-step strategy (see figure): i) Adsorption of thiol-capped metal nanoparticles on graphite, ii) electrochemical modification, iii) potential-induced delivery of the modified nanoparticles to the electrolyte. Thiol-capped gold nanoparticles modified with iron-melanin are attractive because they combine magnetic properties and biocompatibility. The biopolymer modified nanoparticles are prepared and delivered following a three step strategy: i) adsorption of thiol-capped metal nanoparticles on graphite, ii) electrochemical deposition of melanin-iron, iii) potential-induced delivery of the modified nanoparticles to the electrolyte.

  1. Tyrosine and the synthesis of melanin in embryonic cells fromAmbystoma mexicanum.

    PubMed

    Landström, Ulf; Løvtrup, Søren

    1978-09-01

    Explants comprising about 15 cells were dissected from various regions of the blastula ofAmbystoma mexicanum and cultured in Barth's medium. By addition of L-tyrosine to the culture medium it was possible to induce melanin synthesis in three different cells types: undifferentiated embryonic cells, mesenchyme cells and nerve cells. Tyrosine was found to act as an inductor in a very low concentration (1 μM). It is suggested that tyrosine serves both as an inductor and as a substrate for melanin synthesis in the amphibian larva.

  2. Simultaneous in vivo imaging of melanin and lipofuscin in the retina with multimodal photoacoustic ophthalmoscopy

    NASA Astrophysics Data System (ADS)

    Zhang, Xiangyang; Zhang, Hao F.; Zhou, Lixiang; Jiao, Shuliang

    2012-02-01

    We combined photoacoustic ophthalmoscopy (PAOM) with autofluorescence imaging for simultaneous in vivo imaging of dual molecular contrasts in the retina using a single light source. The dual molecular contrasts come from melanin and lipofuscin in the retinal pigment epithelium (RPE). Melanin and lipofuscin are two types of pigments and are believed to play opposite roles (protective vs. exacerbate) in the RPE in the aging process. We successfully imaged the retina of pigmented and albino rats at different ages. The experimental results showed that multimodal PAOM system can be a potentially powerful tool in the study of age-related degenerative retinal diseases.

  3. Biochemical characterization of three hamster melanoma variants--I. Tyrosinase activity and melanin content.

    PubMed

    Słomiński, A; Scisłowski, P W; Bomirski, A

    1984-01-01

    Tyrosinase activity in the soluble fraction of the cells and melanin content in the whole cells of the black-melanotic (Ma), brown-melanotic (MI) and amelanotic (Ab) hamster melanomas were studied. The activity of the soluble tyrosinase was highest in MI lower in Ma, and very low in Ab melanoma. Melanin content was greatest in the Ma, lower in MI, and none in Ab melanoma. Acrylamide gel electrophoretic pattern of the soluble tyrosinase consisted of 2 bands in Ma and MI melanomas, and of 1 band in Ab melanoma.

  4. The effects of Sophora angustifolia and other natural plant extracts on melanogenesis and melanin transfer in human skin cells.

    PubMed

    Singh, Suman K; Baker, Richard; Wibawa, Judata I D; Bell, Mike; Tobin, Desmond J

    2013-01-01

    Skin pigmentation is a multistep process of melanin synthesis by melanocytes, its transfer to recipient keratinocytes and its degradation. As dyspigmentation is a prominent marker of skin ageing, novel effective agents that modulate pigmentation safely are being sought for both clinical and cosmetic use. Here, a number of plant extracts were examined for their effect on melanogenesis (by melanin assay and Western blotting) and melanin transfer (by confocal immunomicroscopy of gp100-positive melanin granules in cocultures and by SEM analysis of filopodia), in human melanocytes and in cocultures with phototype-matched normal adult epidermal keratinocytes. Mulberry, Kiwi and Sophora extracts were assessed against isobutylmethylxanthine, hydroquinone, vitamin C and niacinamide. Compared with unstimulated control, all extracts significantly reduced melanogenesis in human melanoma cells and normal adult epidermal melanocytes. These extracts also reduced melanin transfer and reduced filopodia expression on melanocytes, similar to hydroquinone and niacinamide, indicating their effectiveness as multimode pigmentation actives. © 2013 John Wiley & Sons A/S.

  5. Lipoxygenase/H2O2-catalyzed oxidation of dihdroxyindoles: synthesis of melanin pigments and study of their antioxidant properties.

    PubMed

    Blarzino, C; Mosca, L; Foppoli, C; Coccia, R; De Marco, C; Rosei, M A

    1999-02-01

    5,6-Dihydroxyindole (DHI) and 5,6-dihydroxyindole-2-carboxylic acid (DHICA), which are important intermediates in melanogenesis, can be converted into the corresponding melanin pigments by the action of the lipoxygenase/H2O2 system. Kinetic and HPLC analyses indicate that both DHI and DHICA are good substrates for this enzymatic system. Enzyme activity on both substrates was measured in comparison with peroxidase and tyrosinase; the oxidizing behaviour of lipoxygenase is more similar to that of peroxidase rather than that of tyrosinase. The antioxidant properties of DHI- and DHICA-melanins have been investigated in comparison with other kinds of melanins. DHICA-melanin shows a more pronounced antioxidant effect than that of DHI-melanin and this behaviour can be ascribed to the different structure and solubility of the two pigments. The mixed polymer synthesized from DHI and DHICA is the most effective one. Some implications about the possible explanation of the above mentioned behaviour are discussed.

  6. Prevention of melanin formation during aryl alcohol oxidase production under growth-limited conditions using an Aspergillus nidulans cell factory.

    PubMed

    Pardo-Planas, Oscar; Prade, Rolf A; Müller, Michael; Atiyeh, Hasan K; Wilkins, Mark R

    2017-11-01

    An Aspergillus nidulans cell factory was genetically engineered to produce an aryl alcohol oxidase (AAO). The cell factory initiated production of melanin when growth-limited conditions were established using stationary plates and shaken flasks. This phenomenon was more pronounced when the strain was cultured in a trickle bed reactor (TBR). This study investigated different approaches to reduce melanin formation in fungal mycelia and liquid medium in order to increase the enzyme production yield. Removal of copper from the medium recipe reduced melanin formation in agar cultures and increased enzyme activities by 48% in agitated liquid cultures. Copper has been reported as a key element for tyrosinase, an enzyme responsible for melanin production. Ascorbic acid (0.44g/L) stopped melanin accumulation, did not affect growth parameters and resulted in AAO activity that was more than two-fold greater than a control treatment with no ascorbic acid. Copyright © 2017 Elsevier Ltd. All rights reserved.

  7. Melanin-concentrating hormone control of sleep-wake behavior.

    PubMed

    Monti, Jaime M; Torterolo, Pablo; Lagos, Patricia

    2013-08-01

    The melanin-concentrating hormone (MCH) is a 19 aminoacid peptide found in mammals predominantly in neurons located in the lateral hypothalamus and incerto-hypothalamic area. The biological function of MCH is mediated by two G-protein-coupled receptors known as MCHR1 and MCHR2, although the latter is expressed only in carnivores, primates and man. The MCHR1 couples to Gi, Gq and Go proteins, with Gi leading to the inhibition of both excitatory and inhibitory synaptic events. Within the central nervous system (CNS) MCH participates in a number of functions including sleep-wake behavior. In this respect, MCHergic neurons project widely throughout the CNS to brain regions involved in the regulation of behavioral states. MCHergic neurons are silent during wakefulness (W), increase their firing during slow wave sleep (SWS) and still more during REM sleep (REMS). Studies in knockout mice for MCH (MCH(-/-)) have shown a reduction in SWS and an increase of W during the light and the dark phase of the light-dark cycle. Moreover, in response to food deprivation a marked reduction in REMS time was observed in these animals. Conflicting effects on sleep variables have been reported in MCHR1(-/-) mice by different authors. The i.c.v. administration of MCH increases REMS and SWS in the rat. In addition, an enhancement of REMS has been described following the microinjection of the neuropeptide into the nucleus pontis oralis of the cat, while its infusion into the dorsal raphe nucleus (DR) and the basal forebrain (horizontal limb of the diagonal band of Broca) is followed by an increase of REMS and a reduction of W in the rat. Immunoneutralization of MCH in the DR augmented W and suppressed REMS in the rat, as did the s.c. injection of selective MCHR1 antagonists. The robust REMS-inducing effect of MCH is likely related to the deactivation of monoaminergic, orexinergic, glutamatergic, cholinergic (W-on) and GABAergic (REM-off) neurons involved in the generation of W and the

  8. Protection of Melanized Cryptococcus neoformans from Lethal Dose Gamma Irradiation Involves Changes in Melanin's Chemical Structure and Paramagnetism

    PubMed Central

    Khajo, Abdelahad; Bryan, Ruth A.; Friedman, Matthew; Burger, Richard M.; Levitsky, Yan; Casadevall, Arturo; Magliozzo, Richard S.; Dadachova, Ekaterina

    2011-01-01

    Certain fungi thrive in highly radioactive environments including the defunct Chernobyl nuclear reactor. Cryptococcus neoformans (C. neoformans), which uses L-3,4-dihydroxyphenylalanine (L-DOPA) to produce melanin, was used here to investigate how gamma radiation under aqueous aerobic conditions affects the properties of melanin, with the aim of gaining insight into its radioprotective role. Exposure of melanized fungal cell in aqueous suspensions to doses of γ-radiation capable of killing 50 to 80% of the cells did not lead to a detectable loss of melanin integrity according to EPR spectra of melanin radicals. Moreover, upon UV-visible (Xe-lamp) illumination of melanized cells, the increase in radical population was unchanged after γ-irradiation. Gamma-irradiation of frozen cell suspensions and storage of samples for several days at 77 K however, produced melanin modification noted by a reduced radical population and reduced photoresponse. More direct evidence for structural modification of melanin came from the detection of soluble products with absorbance maxima near 260 nm in supernatants collected after γ-irradiation of cells and cell-free melanin. These products, which include thiobarbituric acid (TBA)-reactive aldehydes, were also generated by Fenton reagent treatment of cells and cell-free melanin. In an assay of melanin integrity based on the metal (Bi+3) binding capacity of cells, no detectable loss in binding was detected after γ-irradiation. Our results show that melanin in C. neoformans cells is susceptible to some damage by hydroxyl radical formed in lethal radioactive aqueous environments and serves a protective role in melanized fungi that involves sacrificial breakdown. PMID:21966422

  9. Melanins and melanogenesis: from pigment cells to human health and technological applications.

    PubMed

    d'Ischia, Marco; Wakamatsu, Kazumasa; Cicoira, Fabio; Di Mauro, Eduardo; Garcia-Borron, Josè Carlos; Commo, Stephane; Galván, Ismael; Ghanem, Ghanem; Kenzo, Koike; Meredith, Paul; Pezzella, Alessandro; Santato, Clara; Sarna, Tadeusz; Simon, John D; Zecca, Luigi; Zucca, Fabio A; Napolitano, Alessandra; Ito, Shosuke

    2015-09-01

    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.

  10. Testing in Mice the Hypothesis That Melanin Is Protective in Malaria Infections

    PubMed Central

    Waisberg, Michael; Vickers, Brandi K.; Yager, Stephanie B.; Lin, Christina K.; Pierce, Susan K.

    2012-01-01

    Malaria has had the largest impact of any infectious disease on shaping the human genome, exerting enormous selective pressure on genes that improve survival in severe malaria infections. Modern humans originated in Africa and lost skin melanization as they migrated to temperate regions of the globe. Although it is well documented that loss of melanization improved cutaneous Vitamin D synthesis, melanin plays an evolutionary ancient role in insect immunity to malaria and in some instances melanin has been implicated to play an immunoregulatory role in vertebrates. Thus, we tested the hypothesis that melanization may be protective in malaria infections using mouse models. Congenic C57BL/6 mice that differed only in the gene encoding tyrosinase, a key enzyme in the synthesis of melanin, showed no difference in the clinical course of infection by Plasmodium yoelii 17XL, that causes severe anemia, Plasmodium berghei ANKA, that causes severe cerebral malaria or Plasmodium chabaudi AS that causes uncomplicated chronic disease. Moreover, neither genetic deficiencies in vitamin D synthesis nor vitamin D supplementation had an effect on survival in cerebral malaria. Taken together, these results indicate that neither melanin nor vitamin D production improve survival in severe malaria. PMID:22242171

  11. Melanin precursors prevent premature age-related and noise-induced hearing loss in albino mice.

    PubMed

    Murillo-Cuesta, Silvia; Contreras, Julio; Zurita, Esther; Cediel, Rafael; Cantero, Marta; Varela-Nieto, Isabel; Montoliu, Lluís

    2010-02-01

    Strial melanocytes are required for normal development and correct functioning of the cochlea. Hearing deficits have been reported in albino individuals from different species, although melanin appears to be not essential for normal auditory function. We have analyzed the auditory brainstem responses (ABR) of two transgenic mice: YRT2, carrying the entire mouse tyrosinase (Tyr) gene expression-domain and undistinguishable from wild-type pigmented animals; and TyrTH, non-pigmented but ectopically expressing tyrosine hydroxylase (Th) in melanocytes, which generate the precursor metabolite, L-DOPA, but not melanin. We show that young albino mice present a higher prevalence of profound sensorineural deafness and a poorer recovery of auditory thresholds after noise-exposure than transgenic mice. Hearing loss was associated with absence of cochlear melanin or its precursor metabolites and latencies of the central auditory pathway were unaltered. In summary, albino mice show impaired hearing responses during ageing and after noise damage when compared to YRT2 and TyrTH transgenic mice, which do not show the albino-associated ABR alterations. These results demonstrate that melanin precursors, such as L-DOPA, have a protective role in the mammalian cochlea in age-related and noise-induced hearing loss.

  12. Visualisation of the distributions of melanin and indocyanine green in biological tissues

    SciTech Connect

    Genina, E A; Fedosov, I V; Bashkatov, A N; Zimnyakov, D A; Tuchin, V V; Altshuler, G B

    2008-03-31

    A double-wavelength laser scanning microphotometer with the high spectral and spatial resolutions is developed for studying the distribution of endogenic and exogenic dyes in biological tissues. Samples of hair and skin biopsy with hair follicles stained with indocyanine green are studied. The spatial distribution of indocyanine green and melanin in the biological tissue is determined from the measured optical transmittance. (laser biology)

  13. Positive Relationship between Abdominal Coloration and Dermal Melanin Density in Phrynosomatid Lizards

    Treesearch

    Vanessa S. Quinn; Diana K. Hews

    2003-01-01

    Phrynosomatid lizards show considerable variation among species in the occurrence of a secondary sexual trait, blue abdominal coloration. The production of blue skin may be controlled by at least two cellular components, melanin in melanophores, and guanine in iridophores. To examine the hypothesis that a mechanism producing variation in abdominal coloration is...

  14. Dual functions of a melanin-based ornament in the common yellowthroat

    PubMed Central

    Tarof, Scott A; Dunn, Peter O; Whittingham, Linda A

    2005-01-01

    Melanin-based ornaments often function as signals in male–male competition, whereas carotenoid-based ornaments appear to be important in female mate choice. This difference in function is thought to occur because carotenoid pigments are more costly to produce than melanins and are thus more reliable indicators of male quality. We examined the role of melanin- and carotenoid-based ornaments in male–male competition and female choice in the common yellowthroat Geothlypis trichas, a sexually dichromatic passerine. Males display a black facial mask produced by melanin pigmentation and a bright yellow bib (throat, breast and belly) produced by carotenoid pigmentation. In controlled aviary experiments, mask size was the best predictor of both male–male competition and female mate choice, and, therefore, mask size may be regarded as an ornament of dual function. These dual functions may help to maintain the reliability of mask size as an indicator of male quality, despite the potentially low cost of production. The size of the bib was unrelated to male–male competition or female choice, but there was a tendency for females to prefer males with more colourful bibs. We propose that the black mask is important in competition for territories with other males and for attracting females. Our results highlight the need for more studies of the mechanisms of sexual selection in species with ornaments composed of different pigment types. PMID:16024373

  15. Melanin-independent accumulation of turgor pressure in appressoria of Phakopsora pachyrhizi

    USDA-ARS?s Scientific Manuscript database

    In some plant pathogenic fungi, turgor pressure accumulation in appressoria produces a mechanical force enabling the direct penetration of hyphae through the plant cell epidermis. Melanin has been reported to function as an impermeable barrier to osmolytes, which allow appressoria to accumulate high...

  16. Metal exposure influences the melanin and carotenoid-based colorations in great tits.

    PubMed

    Giraudeau, M; Mateos-Gonzalez, F; Cotín, J; Pagani-Nuñez, E; Torné-Noguera, A; Senar, J C

    2015-11-01

    Metals are naturally found in the environment but are also emitted through anthropogenic activities, raising some concerns about the potential deleterious effects of these elements on wildlife. The potential effects of metals on bird coloration have been the focus of several recent studies since animal colored-signals often reflect the physiology of their bearers and are thus used by animals to assess the quality of another individual as a mate or competitor. These studies have shown that the melanin pigmentation seems to be positively associated and the carotenoid-based coloration negatively associated with metal exposure in wild birds. Although these studies have been very useful to show the associations between metal exposure and coloration, only few of them have actually quantified the levels of metal exposure at the individual level; always focusing on one or two of them. Here, we measured the concentrations of eight metals in great tits' feathers and then assessed how these levels of metals were associated with the carotenoid and melanin-based colorations. We found that the melanin pigmentation was positively associated with the copper concentration and negatively correlated with the chromium concentration in feathers. In addition, we have shown that the carotenoid-based coloration was negatively associated with the feather's mercury concentration. This study is the first one to identify some metals that might affect positively and negatively the deposition of melanin and carotenoid into the plumage of wild birds.

  17. Interpreting melanin-based coloration through deep time: a critical review

    PubMed Central

    Lindgren, Johan; Moyer, Alison; Schweitzer, Mary H.; Sjövall, Peter; Uvdal, Per; Nilsson, Dan E.; Heimdal, Jimmy; Engdahl, Anders; Gren, Johan A.; Schultz, Bo Pagh; Kear, Benjamin P.

    2015-01-01

    Colour, derived primarily from melanin and/or carotenoid pigments, is integral to many aspects of behaviour in living vertebrates, including social signalling, sexual display and crypsis. Thus, identifying biochromes in extinct animals can shed light on the acquisition and evolution of these biological traits. Both eumelanin and melanin-containing cellular organelles (melanosomes) are preserved in fossils, but recognizing traces of ancient melanin-based coloration is fraught with interpretative ambiguity, especially when observations are based on morphological evidence alone. Assigning microbodies (or, more often reported, their ‘mouldic impressions’) as melanosome traces without adequately excluding a bacterial origin is also problematic because microbes are pervasive and intimately involved in organismal degradation. Additionally, some forms synthesize melanin. In this review, we survey both vertebrate and microbial melanization, and explore the conflicts influencing assessment of microbodies preserved in association with ancient animal soft tissues. We discuss the types of data used to interpret fossil melanosomes and evaluate whether these are sufficient for definitive diagnosis. Finally, we outline an integrated morphological and geochemical approach for detecting endogenous pigment remains and associated microstructures in multimillion-year-old fossils. PMID:26290071

  18. LASER BIOLOGY: Visualisation of the distributions of melanin and indocyanine green in biological tissues

    NASA Astrophysics Data System (ADS)

    Genina, E. A.; Fedosov, I. V.; Bashkatov, A. N.; Zimnyakov, D. A.; Altshuler, G. B.; Tuchin, V. V.

    2008-03-01

    A double-wavelength laser scanning microphotometer with the high spectral and spatial resolutions is developed for studying the distribution of endogenic and exogenic dyes in biological tissues. Samples of hair and skin biopsy with hair follicles stained with indocyanine green are studied. The spatial distribution of indocyanine green and melanin in the biological tissue is determined from the measured optical transmittance.

  19. Dual-wavelength pump-probe microscopy analysis of melanin composition

    NASA Astrophysics Data System (ADS)

    Thompson, Andrew; Robles, Francisco E.; Wilson, Jesse W.; Deb, Sanghamitra; Calderbank, Robert; Warren, Warren S.

    2016-11-01

    Pump-probe microscopy is an emerging technique that provides detailed chemical information of absorbers with sub-micrometer spatial resolution. Recent work has shown that the pump-probe signals from melanin in human skin cancers correlate well with clinical concern, but it has been difficult to infer the molecular origins of these differences. Here we develop a mathematical framework to describe the pump-probe dynamics of melanin in human pigmented tissue samples, which treats the ensemble of individual chromophores that make up melanin as Gaussian absorbers with bandwidth related via Frenkel excitons. Thus, observed signals result from an interplay between the spectral bandwidths of the individual underlying chromophores and spectral proximity of the pump and probe wavelengths. The model is tested using a dual-wavelength pump-probe approach and a novel signal processing method based on gnomonic projections. Results show signals can be described by a single linear transition path with different rates of progress for different individual pump-probe wavelength pairs. Moreover, the combined dual-wavelength data shows a nonlinear transition that supports our mathematical framework and the excitonic model to describe the optical properties of melanin. The novel gnomonic projection analysis can also be an attractive generic tool for analyzing mixing paths in biomolecular and analytical chemistry.

  20. Differential effects of endoparasitism on the expression of carotenoid- and melanin-based ornamental coloration.

    PubMed Central

    McGraw, K J; Hill, G E

    2000-01-01

    The striking diversity of sexual dimorphisms in nature begs the question: Why are there so many signal types? One possibility is that ornamental traits convey different sets of information about the quality of the sender to the receiver. The colourful, pigmented feathers of male birds seem to meet the predictions of this hypothesis. Evidence suggests that carotenoid pigmentation reflects the nutritional condition of males during moult, whereas in many instances melanin pigmentation is a reliable indicator of social status. However, as of yet there have been no experimental tests to determine how these two ornament types respond to the same form of environmental stress. In this study, we tested the effect of endoparasitic infection by intestinal coccidians (Isospora sp.) on the expression of both carotenoid- and melanin-based ornamental coloration in captive male American goldfinches (Carduelis tristis). We found that the carotenoid-based plumage and bill coloration of parasitized males was less saturated than that developed by unparasitized males, but that the brightness and size of melanin-based black caps did not differ between the groups. These findings provide the most robust empirical support to date for the notion that carotenoid and melanin ornaments reveal different information to conspecifics. PMID:11007328

  1. Aspergillus fumigatus melanins: interference with the host endocytosis pathway and impact on virulence

    PubMed Central

    Heinekamp, Thorsten; Thywißen, Andreas; Macheleidt, Juliane; Keller, Sophia; Valiante, Vito; Brakhage, Axel A.

    2013-01-01

    The opportunistic human pathogenic fungus Aspergillus fumigatus produces at least two types of melanin, namely pyomelanin and dihydroxynaphthalene (DHN) melanin. Pyomelanin is produced during tyrosine catabolism via accumulation of homogentisic acid. Although pyomelanin protects the fungus against reactive oxygen species (ROS) and acts as a defense compound in response to cell wall stress, mutants deficient for pyomelanin biosynthesis do not differ in virulence when tested in a murine infection model for invasive pulmonary aspergillosis. DHN melanin is responsible for the characteristic gray-greenish color of A. fumigatus conidia. Mutants lacking a functional polyketide synthase PksP, the enzyme responsible for the initial step in DHN-melanin formation, i.e., the synthesis of naphthopyrone, produce white spores and are attenuated in virulence. The activity of PksP was found to be essential not only for inhibition of apoptosis of phagocytes by interfering with the host PI3K/Akt signaling cascade but also for effective inhibition of acidification of conidia-containing phagolysosomes. These features allow A. fumigatus to survive in phagocytes and thereby to escape from human immune effector cells and to become a successful pathogen. PMID:23346079

  2. Methionine supplementation influences melanin-based plumage colouration in Eurasian kestrel, Falco tinnunculus, nestlings.

    PubMed

    Parejo, Deseada; Silva, Nadia

    2009-11-01

    The extent to which the expression of melanin-based plumage colouration in birds is genetically or environmentally determined is controversial. Here, we performed a between-nest design supplementation with either the sulphur amino acid dl-methionine or with water to investigate the importance of the non-genetic component of melanin-based plumage colouration in the Eurasian kestrel, Falco tinnunculus. Methionine affects growth and immunity, thus we aimed to modify nestling growth and immunity before feather development. Then, we measured the effect of the experiment on colouration of two melanin-based plumage patches of nestling kestrels. We found that methionine slowed down nestling growth through treatment administration and that nestlings compensated by speeding up their growth later. We did not find any effects of methionine on nestling immunity (i.e. lymphocyte counts, natural antibody levels or complement-mediated immunity). Effects on growth seemed to be mirrored by changes in nestling colouration in the two sexes: methionine-nestlings showed less intense brown plumage on their backs compared with control nestlings. These results provide support for a non-genetic determination of a melanin-based plumage patch in the two sexes of nestling kestrels.

  3. Melanin-based color of plumage: role of condition and of feathers' microstructure

    USGS Publications Warehouse

    D'Alba, Liliana; Van Hemert, Caroline R.; Spencer, Karen A.; Heidinger, Britt J.; Gill, Lisa; Evans, Neil P.; Monaghan, Pat; Handel, Colleen M.; Shawkey, Matthew D.

    2014-01-01

    Whether melanin-based colors honestly signal a bird's condition during the growth of feathers is controversial, and it is unclear if or how the physiological processes underlying melanogenesis or color-imparting structural feather microstructure may be adversely affected by condition. Here we report results from two experiments designed to measure the effect of condition on expression of eumelanic and pheomelanic coloration in black-capped chickadees (Poecile atricapillus) and zebra finches (Taeniopygia guttata), respectively. In chickadees, we compared feathers of birds affected and unaffected by avian keratin disorder, while in zebra finches we compared feathers of controls with feathers of those subjected to an unpredictable food supply during development. In both cases we found that control birds had brighter feathers (higher total reflectance) and more barbules, but similar densities of melanosomes. In addition, the microstructure of the feathers explained variation in color more strongly than did melanosome density. Together, these results suggest that melanin-based coloration may in part be condition-dependent, but that this may be driven by changes in keratin and feather development, rather than melanogenesis itself. Researchers should be cautious when assigning variation in melanin-based color to melanin alone and microstructure of the feather should be taken into account.

  4. Inhibition of melanin production by a combination of Siberian larch and pomegranate fruit extracts.

    PubMed

    Diwakar, Ganesh; Rana, Jatinder; Scholten, Jeffrey D

    2012-09-01

    In an effort to find botanicals containing polyphenolic compounds with the capacity to inhibit melanin biosynthesis, we identified a novel combination of Siberian larch (Larix sibirica) extract, standardized to 80% taxifolin, and pomegranate fruit (Punica granatum) extract, containing 20% punicalagins, that demonstrates a synergistic reduction of melanin biosynthesis in Melan-a cells. The combination of Siberian larch and pomegranate extracts (1:1) produced a 2-fold reduction in melanin content compared to Siberian larch or pomegranate extracts alone with no corresponding effect on cell viability. Siberian larch and pomegranate fruit extracts inhibited expression of melanocyte specific genes, tyrosinase (Tyr), microphthalmia transcription factor (Mitf), and melanosome structural proteins (Pmel17 and Mart1) but did not inhibit tyrosinase enzyme activity. These results suggest that the mechanism of inhibition of melanin biosynthesis by Siberian larch and pomegranate extracts, alone and in combination, is through downregulation of melanocyte specific genes and not due to inhibition of tyrosinase enzyme activity. Copyright © 2012 Elsevier B.V. All rights reserved.

  5. Technological Desition of Extraction of Melanin from the Waste of Production of Sunflower-Seed Oil

    NASA Astrophysics Data System (ADS)

    Kartushina, Yu N.; Nefedieva, E. E.; Sevriukova, G. A.; Gracheva, N. V.; Zheltobryukhov, V. F.

    2017-05-01

    The research was realized in the field of the technology for re-use of waste of sunflower-seed oil production. A technological scheme of production of melanin from sunflower husk as a waste was developed. Re-cycling will give the opportunity to reduce the amount of waste and to obtain an additional source of income.

  6. Using size exclusion chromatography to monitor the synthesis of melanins from catecholamines.

    PubMed

    Vercruysse, Koen P; Clark, Astiney M; Bello, Paola A F; Alhumaidi, Majidah

    2017-09-01

    We have employed size exclusion chromatography (SEC) to the study of the auto- and Cu(2+)-mediated oxidation of the catecholamines, dopamine, epinephrine and norepinephrine, into melanins. We observed that, due to non-size exclusion-mediated effects, the catecholamines and some of the low molecular mass intermediates generated during the oxidation reactions, could be resolved from each other and from the high molecular mass pigment generated. Thus, SEC allowed us to monitor the disappearance of the catecholamine starting compounds, the appearance and subsequent disappearance of the low molecular mass chromophores generated in the initial phase of the reactions and the appearance of the high molecular mass melanins. In the process of this research, we observed that many, mostly anionic polysaccharides (PS), enhanced both the auto- and Cu(2+)-mediated oxidation of all three catecholamines. SEC analyses of reaction mixtures involving PS suggested that very high molecular mass aggregates between PS and melanins can be generated. In addition, SEC analysis allowed us to verify the efficiency of the dialysis purification process employed to obtain pure and dried melanin materials for cell-biological studies. Copyright © 2017 Elsevier B.V. All rights reserved.

  7. Effect of Purified Mushroom Tyrosinase on Melanin Content and Melanogenic Protein Expression

    PubMed Central

    Ali, Ayesha S.

    2016-01-01

    In mammalian melanocytes, melanosome is a highly specialized organelle where melanin is synthesized. Melanin synthesis is controlled by tyrosinase, the vital enzyme in melanogenic pathway. The present investigation is based on an effect of purified mushroom tyrosinase of Agaricus bisporus on B16F10 melanocytes for the melanin production via blocking pigment cell machinery. Using B16F10 melanocytes showed that the stimulation of melanogenesis by purified tyrosinase is due to increased tyrosinase absorption. Cellular tyrosinase activity and melanin content in B16F10 melanocytes were increased by purified tyrosinase in a dose-dependent manner. Western blot analysis revealed that cellular tyrosinase levels were enhanced after treatment with purified tyrosinase for 48 hours. Furthermore, tyrosinase induced phosphorylation of cyclic adenosine monophosphate (cAMP) response element-binding protein (CREB) in a dose-dependent manner. The purified tyrosinase-mediated increase of tyrosinase activity was significantly attenuated by H89, LY294002, Ro-32-0432, and PD98059, cAMP-dependent protein kinase inhibitors. The results indicate that purified tyrosinase can be used as contestant for the treatment of vitiligous skin conditions. PMID:27699070

  8. Transferring biomarker into molecular probe: Melanin nanoparticle as a naturally active platform for multimodality imaging

    DOE PAGES

    Fan, Quli; Cheng, Kai; Hu, Xiang; ...

    2014-10-07

    Developing multifunctional and easily prepared nanoplatforms with integrated different modalities is highly challenging for molecular imaging. Here, we report the successful transfer of an important molecular target, melanin, into a novel multimodality imaging nanoplatform. Melanin is abundantly expressed in melanotic melanomas and thus has been actively studied as a target for melanoma imaging. In our work, the multifunctional biopolymer nanoplatform based on ultrasmall (<10 nm) water-soluble melanin nanoparticle (MNP) was developed and showed unique photoacoustic property and natural binding ability with metal ions (for example, 64Cu2+, Fe3+). Therefore, MNP can serve not only as a photoacoustic contrast agent, but alsomore » as a nanoplatform for positron emission tomography (PET) and magnetic resonance imaging (MRI). Traditional passive nanoplatforms require complicated and time-consuming processes for prebuilding reporting moieties or chemical modifications using active groups to integrate different contrast properties into one entity. In comparison, utilizing functional biomarker melanin can greatly simplify the building process. We further conjugated αvβ3 integrins, cyclic c(RGDfC) peptide, to MNPs to allow for U87MG tumor accumulation due to its targeting property combined with the enhanced permeability and retention (EPR) effect. As a result, the multimodal properties of MNPs demonstrate the high potential of endogenous materials with multifunctions as nanoplatforms for molecular theranostics and clinical translation.« less

  9. Dual-wavelength pump-probe microscopy analysis of melanin composition

    PubMed Central

    Thompson, Andrew; Robles, Francisco E.; Wilson, Jesse W.; Deb, Sanghamitra; Calderbank, Robert; Warren, Warren S.

    2016-01-01

    Pump-probe microscopy is an emerging technique that provides detailed chemical information of absorbers with sub-micrometer spatial resolution. Recent work has shown that the pump-probe signals from melanin in human skin cancers correlate well with clinical concern, but it has been difficult to infer the molecular origins of these differences. Here we develop a mathematical framework to describe the pump-probe dynamics of melanin in human pigmented tissue samples, which treats the ensemble of individual chromophores that make up melanin as Gaussian absorbers with bandwidth related via Frenkel excitons. Thus, observed signals result from an interplay between the spectral bandwidths of the individual underlying chromophores and spectral proximity of the pump and probe wavelengths. The model is tested using a dual-wavelength pump-probe approach and a novel signal processing method based on gnomonic projections. Results show signals can be described by a single linear transition path with different rates of progress for different individual pump-probe wavelength pairs. Moreover, the combined dual-wavelength data shows a nonlinear transition that supports our mathematical framework and the excitonic model to describe the optical properties of melanin. The novel gnomonic projection analysis can also be an attractive generic tool for analyzing mixing paths in biomolecular and analytical chemistry. PMID:27833147

  10. Interpreting melanin-based coloration through deep time: a critical review.

    PubMed

    Lindgren, Johan; Moyer, Alison; Schweitzer, Mary H; Sjövall, Peter; Uvdal, Per; Nilsson, Dan E; Heimdal, Jimmy; Engdahl, Anders; Gren, Johan A; Schultz, Bo Pagh; Kear, Benjamin P

    2015-08-22

    Colour, derived primarily from melanin and/or carotenoid pigments, is integral to many aspects of behaviour in living vertebrates, including social signalling, sexual display and crypsis. Thus, identifying biochromes in extinct animals can shed light on the acquisition and evolution of these biological traits. Both eumelanin and melanin-containing cellular organelles (melanosomes) are preserved in fossils, but recognizing traces of ancient melanin-based coloration is fraught with interpretative ambiguity, especially when observations are based on morphological evidence alone. Assigning microbodies (or, more often reported, their 'mouldic impressions') as melanosome traces without adequately excluding a bacterial origin is also problematic because microbes are pervasive and intimately involved in organismal degradation. Additionally, some forms synthesize melanin. In this review, we survey both vertebrate and microbial melanization, and explore the conflicts influencing assessment of microbodies preserved in association with ancient animal soft tissues. We discuss the types of data used to interpret fossil melanosomes and evaluate whether these are sufficient for definitive diagnosis. Finally, we outline an integrated morphological and geochemical approach for detecting endogenous pigment remains and associated microstructures in multimillion-year-old fossils.

  11. Near-infrared autofluorescence imaging of cutaneous melanins and human skin in vivo

    NASA Astrophysics Data System (ADS)

    Han, Xiao; Lui, Harvey; McLean, David I.; Zeng, Haishan

    2009-03-01

    In recent years, near-infrared (NIR) autofluorescence imaging has been explored as a novel technique for tissue evaluation and diagnosis. We present an NIR fluorescence imaging system optimized for the dermatologic clinical setting, with particular utility for the direct characterization of cutaneous melanins in vivo. A 785-nm diode laser is coupled into a ring light guide to uniformly illuminate the skin. A bandpass filter is used to purify the laser light for fluorescence excitation, while a long-pass filter is used to block the main laser wavelength but pass the spontaneous components for NIR reflectance imaging. A computer-controlled filter holder is used to switch these two filters to select between reflectance and fluorescence imaging modes. Both the reflectance and fluorescence photons are collected by an NIR-sensitive charge-coupled device (CCD) camera to form the respective images. Preliminary results show that cutaneous melanin in pigmented skin disorders emits higher NIR autofluorescence than surrounding normal tissue. This confirmed our previous findings from NIR fluorescence spectroscopy study of cutaneous melanins and provides a new approach to directly image the distributions of cutaneous melanins in the skin. In-vivo NIR autofluorescence images may be useful for clinical evaluation and diagnosis of pigmented skin lesions, including melanoma.

  12. [Obtaining of water soluble microbial melanin and study of its some properties].

    PubMed

    Agadzhanian, A A; Asaturian, R A; Ambartsumian, A A; Sargisian, L B; Ovsepian, A S; Vardanian, A H; Sagiian, A S

    2011-01-01

    The effective sorption method for melanin isolation and purification from fermentation solutions of Bacillus thuringiensis serovar galleriae K1 has been elaborated, the principle process flowsheet is presented. The identification of obtained pigment with the samples of natural and synthetic melanin was done by IR-spectroscopy, and the intensity ratio of optical absorption at 650 and 500 nm allows to refer the isolated melanin to eumelanin class. By thermal treatment it was determined, that melanin's amorphous sediment is steady at up to 120 degrees C temperatures, at that the concentration of paramagnetic centers is changed from 0.053 x 10(18) spin/g (48 degrees C) to 0.25 x 10(18) spin/g (120 degrees C). The rising of the temperature of treatment up to 210 degrees C brings to substantial increase of the concentration of unpaired electrons, and at 280 degrees C its sharp growth is observed. At 350 degrees C growth stops, then sharp decrease is observed. The obtained results were confirmed by methods of IR spectroscopy and derivatographic analysis.

  13. Silver nanoparticles mediated altered gene expression of melanin biosynthesis genes in Bipolaris sorokiniana.

    PubMed

    Mishra, Sandhya; Singh, H B

    2015-03-01

    Melanin production in many fungal phytopathogens has been investigated to play direct or indirect role in pathogenesis. However, in Bipolaris sorokiniana, the spot blotch pathogen of wheat, much less is known about the role melanin play in pathogenesis. As an extension of our previous report, the present study aims to investigate the plausible association between melanin production and virulence factor in B. sorokiniana. In the previous study, we carried out analysis on the antifungal efficacy of biosynthesized silver nanoparticles (AgNPs) against B. sorokiniana. The present investigation revealed the gene expression analysis of melanin biosynthesis genes viz. polyketide synthase (PKS1) and scytalone dehydratase (SCD1) under the influence of AgNPs. The 0.05mg/ml concentration of AgNPs yielded noticeable inhibition of B. sorokiniana growth, while 0.1mg/ml concentration of AgNPs accounted for complete inhibition of pathogen growth. In addition, the semiquantitative RT-PCR analysis exhibited reduced expression of PKS1 and SCD1 under the influence of AgNPs treatment. Furthermore, the qRT-PCR demonstrated 6.47 and 1.808 fold significant decrease in the expression pattern of PKS1 and SCD1, respectively, in B. sorokiniana treated with AgNPs. The present study provides probable understanding of molecular events underlying the antifungal role of AgNPs against B. sorokiniana.

  14. Noise-induced hearing loss: the effect of melanin in the stria vascularis.

    PubMed

    Bartels, S; Ito, S; Trune, D R; Nuttall, A L

    2001-04-01

    Conflicting investigations regarding the potential protective effect of melanin against noise-induced sensorineural hearing loss have suggested that eumelanin and pheomelanin may have differing effects within the stria vascularis. Three strains of C57BL/6J mice, (+/+, a/a) wild-types (dark coats/black eyes), (c2j/c2j, a/a), albinos (white coats/pink eyes), and (+/+, Ay/Ay) yellow mice (yellow coats/black eyes), were subjected to five consecutive days of broad band noise exposure at 112 dB(A) SPL for 3 h/day. Cochlear function was evaluated with auditory brainstem response audiometry to pure tones immediately pre-exposure, 5-6 h postexposure, and 14 days post-exposure. No significant difference in the degree of sensorineural hearing loss induced in the three strains of mice was identified. The eumelanin and pheomelanin content of each stria vascularis and amount of protein per stria for both mouse and guinea pig (2/NCR) were determined via high performance liquid chromatography. No pheomelanin was found in the stria of yellow mice, suggesting that coat color is not an accurate predictor of strial melanin content. The melanin content per mg of strial protein was higher in mice than in guinea pigs. A species-specific difference in melanin content does not explain the absence of a protective effect in mice.

  15. Dual-wavelength pump-probe microscopy analysis of melanin composition.

    PubMed

    Thompson, Andrew; Robles, Francisco E; Wilson, Jesse W; Deb, Sanghamitra; Calderbank, Robert; Warren, Warren S

    2016-11-11

    Pump-probe microscopy is an emerging technique that provides detailed chemical information of absorbers with sub-micrometer spatial resolution. Recent work has shown that the pump-probe signals from melanin in human skin cancers correlate well with clinical concern, but it has been difficult to infer the molecular origins of these differences. Here we develop a mathematical framework to describe the pump-probe dynamics of melanin in human pigmented tissue samples, which treats the ensemble of individual chromophores that make up melanin as Gaussian absorbers with bandwidth related via Frenkel excitons. Thus, observed signals result from an interplay between the spectral bandwidths of the individual underlying chromophores and spectral proximity of the pump and probe wavelengths. The model is tested using a dual-wavelength pump-probe approach and a novel signal processing method based on gnomonic projections. Results show signals can be described by a single linear transition path with different rates of progress for different individual pump-probe wavelength pairs. Moreover, the combined dual-wavelength data shows a nonlinear transition that supports our mathematical framework and the excitonic model to describe the optical properties of melanin. The novel gnomonic projection analysis can also be an attractive generic tool for analyzing mixing paths in biomolecular and analytical chemistry.

  16. Testing in mice the hypothesis that melanin is protective in malaria infections.

    PubMed

    Waisberg, Michael; Vickers, Brandi K; Yager, Stephanie B; Lin, Christina K; Pierce, Susan K

    2012-01-01

    Malaria has had the largest impact of any infectious disease on shaping the human genome, exerting enormous selective pressure on genes that improve survival in severe malaria infections. Modern humans originated in Africa and lost skin melanization as they migrated to temperate regions of the globe. Although it is well documented that loss of melanization improved cutaneous Vitamin D synthesis, melanin plays an evolutionary ancient role in insect immunity to malaria and in some instances melanin has been implicated to play an immunoregulatory role in vertebrates. Thus, we tested the hypothesis that melanization may be protective in malaria infections using mouse models. Congenic C57BL/6 mice that differed only in the gene encoding tyrosinase, a key enzyme in the synthesis of melanin, showed no difference in the clinical course of infection by Plasmodium yoelii 17XL, that causes severe anemia, Plasmodium berghei ANKA, that causes severe cerebral malaria or Plasmodium chabaudi AS that causes uncomplicated chronic disease. Moreover, neither genetic deficiencies in vitamin D synthesis nor vitamin D supplementation had an effect on survival in cerebral malaria. Taken together, these results indicate that neither melanin nor vitamin D production improve survival in severe malaria.

  17. Inhibitory Effect of Arctigenin from Fructus Arctii Extract on Melanin Synthesis via Repression of Tyrosinase Expression

    PubMed Central

    Park, Hwayong; Song, Kwang Hoon; Jung, Pil Mun; Kim, Ji-Eun; Kim, Mi Yoon; Ma, Jin Yeul

    2013-01-01

    To identify the active compound arctigenin in Fructus Arctii (dried seed of medicinal plant Arctium lappa) and to elucidate the inhibitory mechanism in melanogenesis, we analyzed melanin content and tyrosinase activity on B16BL6 murine melanoma and melan-A cell cultures. Water extracts of Fructus Arctii were shown to inhibit tyrosinase activity in vitro and melanin content in α-melanocyte stimulating hormone-stimulated cells to similar levels as the well-known kojic acid and arbutin, respectively. The active compound arctigenin of Fructus Arctii displayed little or no cytotoxicity at all concentrations examined and decreased the relative melanin content and tyrosinase activity in a dose-dependent manner. Melanogenic inhibitory activity was also identified in vivo with zebrafish embryo. To determine the mechanism of inhibition, the effects of arctigenin on tyrosinase gene expression and tyrosinase promoter activity were examined. Also in addition, in the signaling cascade, arctigenin dose dependently decreased the cAMP level and promoted the phosphorylation of extracellular signal-regulated kinase. This result suggests that arctigenin downregulates cAMP and the tyrosinase enzyme through its gene promoter and subsequently upregulates extracellular signal-regulated kinase activity by increasing phosphorylation in the melanogenesis signaling pathway, which leads to a lower melanin content. PMID:23781272

  18. Inhibitory Effect of Arctigenin from Fructus Arctii Extract on Melanin Synthesis via Repression of Tyrosinase Expression.

    PubMed

    Park, Hwayong; Song, Kwang Hoon; Jung, Pil Mun; Kim, Ji-Eun; Ro, Hyunju; Kim, Mi Yoon; Ma, Jin Yeul

    2013-01-01

    To identify the active compound arctigenin in Fructus Arctii (dried seed of medicinal plant Arctium lappa) and to elucidate the inhibitory mechanism in melanogenesis, we analyzed melanin content and tyrosinase activity on B16BL6 murine melanoma and melan-A cell cultures. Water extracts of Fructus Arctii were shown to inhibit tyrosinase activity in vitro and melanin content in α -melanocyte stimulating hormone-stimulated cells to similar levels as the well-known kojic acid and arbutin, respectively. The active compound arctigenin of Fructus Arctii displayed little or no cytotoxicity at all concentrations examined and decreased the relative melanin content and tyrosinase activity in a dose-dependent manner. Melanogenic inhibitory activity was also identified in vivo with zebrafish embryo. To determine the mechanism of inhibition, the effects of arctigenin on tyrosinase gene expression and tyrosinase promoter activity were examined. Also in addition, in the signaling cascade, arctigenin dose dependently decreased the cAMP level and promoted the phosphorylation of extracellular signal-regulated kinase. This result suggests that arctigenin downregulates cAMP and the tyrosinase enzyme through its gene promoter and subsequently upregulates extracellular signal-regulated kinase activity by increasing phosphorylation in the melanogenesis signaling pathway, which leads to a lower melanin content.

  19. Melanin-based color of plumage: role of condition and of feathers' microstructure.

    PubMed

    D'Alba, Liliana; Van Hemert, Caroline; Spencer, Karen A; Heidinger, Britt J; Gill, Lisa; Evans, Neil P; Monaghan, Pat; Handel, Colleen M; Shawkey, Matthew D

    2014-10-01

    Whether melanin-based colors honestly signal a bird's condition during the growth of feathers is controversial, and it is unclear if, or how, the physiological processes underlying melanogenesis or the role of the microstructure of feathers in imparting structural color to feathers may be adversely affected by condition. Here, we report results from two experiments designed to measure the effect of condition on expression of eumelanic and pheomelanic coloration in black-capped chickadees (Poecile atricapillus) and zebra finches (Taeniopygia guttata), respectively. In chickadees, we compared feathers of birds affected and unaffected by avian keratin disorder, whereas in zebra finches we compared feathers of controls with feathers of those subjected to an unpredictable food supply during development. In both cases, we found that control birds had brighter feathers (higher total reflectance) and more barbules, but similar densities of melanosomes. In addition, the microstructure of the feathers explained variation in color more strongly than did melanosome density. Together, these results suggest that melanin-based coloration may in part be condition-dependent, but that this may be driven by changes in keratin and feather development, rather than melanogenesis itself. Researchers should be cautious when assigning variation in melanin-based color to melanin alone and microstructure of the feather should be taken into account.

  20. Surface structure characterization of Aspergillus fumigatus conidia mutated in the melanin synthesis pathway and their human cellular immune response.

    PubMed

    Bayry, Jagadeesh; Beaussart, Audrey; Dufrêne, Yves F; Sharma, Meenu; Bansal, Kushagra; Kniemeyer, Olaf; Aimanianda, Vishukumar; Brakhage, Axel A; Kaveri, Srini V; Kwon-Chung, Kyung J; Latgé, Jean-Paul; Beauvais, Anne

    2014-08-01

    In Aspergillus fumigatus, the conidial surface contains dihydroxynaphthalene (DHN)-melanin. Six-clustered gene products have been identified that mediate sequential catalysis of DHN-melanin biosynthesis. Melanin thus produced is known to be a virulence factor, protecting the fungus from the host defense mechanisms. In the present study, individual deletion of the genes involved in the initial three steps of melanin biosynthesis resulted in an altered conidial surface with masked surface rodlet layer, leaky cell wall allowing the deposition of proteins on the cell surface and exposing the otherwise-masked cell wall polysaccharides at the surface. Melanin as such was immunologically inert; however, deletion mutant conidia with modified surfaces could activate human dendritic cells and the subsequent cytokine production in contrast to the wild-type conidia. Cell surface defects were rectified in the conidia mutated in downstream melanin biosynthetic pathway, and maximum immune inertness was observed upon synthesis of vermelone onward. These observations suggest that although melanin as such is an immunologically inert material, it confers virulence by facilitating proper formation of the A. fumigatus conidial surface.

  1. Melanin is required for the formation of the multi-cellular conidia in the endophytic fungus Pestalotiopsis microspora.

    PubMed

    Yu, Xi; Huo, Liang; Liu, Heng; Chen, Longfei; Wang, Yu; Zhu, Xudong

    2015-10-01

    Melanin plays an important role in regulating various biological processes in many fungi. However, its biological role in conidiation remains largely elusive. We report here that conidia production, morphogenesis, integrity, germination and their viability in Pestalotiopsis microspora require the polyketide-derived melanin. A polyketide synthase gene, pks1, was identified and demonstrated responsible for melanin biosynthesis in this fungus. A targeted deletion mutant strain Δpks1 displayed a defect in pigmentation of conidia and had an albino colonial phenotype. Interestingly, Δpks1 produced approximately 6-fold as many conidia as the wild type did, suggesting a negative modulation of melanin on conidia production in this fungus. Moreover, the conidia failed to develop into the normal five-cell morphology, rather the three main-body cells separated via constriction at the original septum position to generate three independent mutant conidia. This result suggests a novel role of melanin in the formation of the multi-cellular conidia. Germ tubes could develop from the three different types of mutant conidia and kept elongating, despite a significantly lower germination rate was observed for them. Still more, the unpigmented conidia became permeable to Calcofluor White and DAPI, suggesting the integrity of the conidia was impaired. Deliberate inhibition of melanin biosynthesis by a specific inhibitor, tricyclazole, led to a similar phenotypes. This work demonstrates a new function of fungal melanin in conidial development.

  2. Role of melanin in release of extracellular enzymes and selection of aggressive isolates of Bipolaris sorokiniana in barley.

    PubMed

    Chand, Ramesh; Kumar, Manoj; Kushwaha, Chanda; Shah, Kavita; Joshi, Arun K

    2014-08-01

    Eighteen barley isolates of Bipolaris sorokiniana belonging to wild and clonal type of black, mixed and white subpopulations were quantitatively assayed for their melanin content and aggressiveness with respect to production of some of the extracellular enzymes such as cellulase, pectinase, amylase and protease. Cellulase and pectinase constituted major portion of the enzymes recovered from the black, mixed and white isolates. Enzyme production and aggressiveness were relatively higher in melanin devoid or low melanin isolates. The melanin deficient isolates were also differentiated from black and mixed isolates on the basis of variation in internal transcribed spacer region of the ribosomal DNA. Higher enzyme productions positively correlated with area under disease progress curve (AUDPC) and lesion development. Melanin content was negatively correlated with extracellular enzymes and aggressiveness of the isolates. Based on melanin content, lesion size, AUDPC and extracellular enzymes, the isolates were grouped in two major clusters (I and II) with further division of cluster II into two sub-clusters (II-A and II-B). The results appears to indicate a possible role of melanin in release of extracellular enzymes and hence in evolution and selection of aggressive isolates of B. sorokiniana in barley.

  3. Insulin-sensitizing and beneficial lipid-metabolic effects of the water-soluble melanin complex extracted from Inonotus obliquus.

    PubMed

    Lee, Jung-Han; Hyun, Chang-Kee

    2014-09-01

    Inonotus obliquus has been traditionally used for treatment of metabolic diseases; however, the mechanism remains to be elucidated. In this study, we found that the water-soluble melanin complex extracted from I. obliquus improved insulin sensitivity and reduced adiposity in high fat (HF)-fed obese mice. When the melanin complex was treated to 3T3-L1 adipocytes, insulin-stimulated glucose uptake was increased significantly, and its phosphoinositide 3-kinase-dependent action was proven with wortmannin treatment. Additionally, dose-dependent increases in Akt phosphorylation and glucose transporter 4 translocation into the plasma membrane were observed in melanin complex-treated cells. Adiponectin gene expression in 3T3-L1 cells incubated with melanin complex increased which was corroborated by increased AMP-activated protein kinase phosphorylation in HepG2 and C2C12 cells treated with conditioned media from the 3T3-L1 culture. Melanin complex-treated 3T3-L1 cells showed no significant change in expression of several lipogenic genes, whereas enhanced expressions of fatty acid oxidative genes were observed. Similarly, the epididymal adipose tissue of melanin complex-treated HF-fed mice had higher expression of fatty acid oxidative genes without significant change in lipogenic gene expression. Together, these results suggest that the water-soluble melanin complex of I. obliquus exerts antihyperglycemic and beneficial lipid-metabolic effects, making it a candidate for promising antidiabetic agent.

  4. Real-time in vivo confocal laser scanning microscopy of melanin-containing cells: A promising diagnostic intervention.

    PubMed

    Xiang, Wenzhong; Song, Xiuzu; Peng, Jianzhong; Xu, Aie; Bi, Zhigang

    2015-12-01

    The use of noninvasive imaging techniques to evaluate different types of skin lesions is increasing popular. In vivo confocal laser scanning microscopy (CLSM) is a new method for high resolution non-invasive imaging of intact skin in situ and in vivo. Although many studies have investigated melanin-containing cells in lesions by in vivo CLSM, few studies have systematically characterized melanin-containing cells based on their morphology, size, arrangement, density, borders, and brightness. In this study, the characteristics of melanin-containing cells were further investigated by in vivo CLSM. A total of 130 lesions, including common nevi, giant congenital pigmented nevi, vitiligo, melasma, melanoma, and chronic eczema, were imaged by in vivo CLSM. This research helps dermatologists understand the characteristics of melanin-containing cells and facilitate the clinical application of melanin-containing cells in the investigation of dermatological disease. In summary, melanin-containing cells include keratinocytes, melanocytes, macrophages, and melanocytic skin tumor cells. Our study presents the CLSM characteristics of melanin-containing cells to potentially facilitate in vivo diagnosis based on shape, size, arrangement, density, borders, and brightness.

  5. GAMMA RADIATION INTERACTS WITH MELANIN TO ALTER ITS OXIDATION-REDUCTION POTENTIAL AND RESULTS IN ELECTRIC CURRENT PRODUCTION

    SciTech Connect

    Turick, C.; Ekechukwu, A.; Milliken, C.

    2011-05-17

    The presence of melanin pigments in organisms is implicated in radioprotection and in some cases, enhanced growth in the presence of high levels of ionizing radiation. An understanding of this phenomenon will be useful in the design of radioprotective materials. However, the protective mechanism of microbial melanin in ionizing radiation fields has not yet been elucidated. Here we demonstrate through the electrochemical techniques of chronoamperometry, chronopotentiometry and cyclic voltammetry that microbial melanin is continuously oxidized in the presence of gamma radiation. Our findings establish that ionizing radiation interacts with melanin to alter its oxidation-reduction potential. Sustained oxidation resulted in electric current production and was most pronounced in the presence of a reductant, which extended the redox cycling capacity of melanin. This work is the first to establish that gamma radiation alters the oxidation-reduction behavior of melanin, resulting in electric current production. The significance of the work is that it provides the first step in understanding the initial interactions between melanin and ionizing radiation taking place and offers some insight for production of biomimetic radioprotective materials.

  6. An alternative method for the analysis of melanin production in Cryptococcus neoformans sensu lato and Cryptococcus gattii sensu lato.

    PubMed

    Brilhante, Raimunda S N; España, Jaime D A; de Alencar, Lucas P; Pereira, Vandbergue S; Castelo-Branco, Débora de S C M; Pereira-Neto, Waldemiro de A; Cordeiro, Rossana de A; Sidrim, José J C; Rocha, Marcos F G

    2017-10-01

    Melanin is an important virulence factor for several microorganisms, including Cryptococcus neoformans sensu lato and Cryptococcus gattii sensu lato, thus, the assessment of melanin production and its quantification may contribute to the understanding of microbial pathogenesis. The objective of this study was to standardise an alternative method for the production and indirect quantification of melanin in C. neoformans sensu lato and C. gattii sensu lato. Eight C. neoformans sensu lato and three C. gattii sensu lato, identified through URA5 methodology, Candida parapsilosis ATCC 22019 (negative control) and one Hortaea werneckii (positive control) were inoculated on minimal medium agar with or without L-DOPA, in duplicate, and incubated at 35°C, for 7 days. Pictures were taken from the third to the seventh day, under standardised conditions in a photographic chamber. Then, photographs were analysed using grayscale images. All Cryptococcus spp. strains produced melanin after growth on minimal medium agar containing L-DOPA. C. parapsilosis ATCC 22019 did not produce melanin on medium containing L-DOPA, while H. werneckii presented the strongest pigmentation. This new method allows the indirect analysis of melanin production through pixel quantification in grayscale images, enabling the study of substances that can modulate melanin production. © 2017 Blackwell Verlag GmbH.

  7. Surface Structure Characterization of Aspergillus fumigatus Conidia Mutated in the Melanin Synthesis Pathway and Their Human Cellular Immune Response

    PubMed Central

    Bayry, Jagadeesh; Beaussart, Audrey; Dufrêne, Yves F.; Sharma, Meenu; Bansal, Kushagra; Kniemeyer, Olaf; Aimanianda, Vishukumar; Brakhage, Axel A.; Kaveri, Srini V.; Kwon-Chung, Kyung J.

    2014-01-01

    In Aspergillus fumigatus, the conidial surface contains dihydroxynaphthalene (DHN)-melanin. Six-clustered gene products have been identified that mediate sequential catalysis of DHN-melanin biosynthesis. Melanin thus produced is known to be a virulence factor, protecting the fungus from the host defense mechanisms. In the present study, individual deletion of the genes involved in the initial three steps of melanin biosynthesis resulted in an altered conidial surface with masked surface rodlet layer, leaky cell wall allowing the deposition of proteins on the cell surface and exposing the otherwise-masked cell wall polysaccharides at the surface. Melanin as such was immunologically inert; however, deletion mutant conidia with modified surfaces could activate human dendritic cells and the subsequent cytokine production in contrast to the wild-type conidia. Cell surface defects were rectified in the conidia mutated in downstream melanin biosynthetic pathway, and maximum immune inertness was observed upon synthesis of vermelone onward. These observations suggest that although melanin as such is an immunologically inert material, it confers virulence by facilitating proper formation of the A. fumigatus conidial surface. PMID:24818666

  8. Rab11b mediates melanin transfer between donor melanocytes and acceptor keratinocytes via coupled exo/endocytosis.

    PubMed

    Tarafder, Abul K; Bolasco, Giulia; Correia, Maria S; Pereira, Francisco J C; Iannone, Lucio; Hume, Alistair N; Kirkpatrick, Niall; Picardo, Mauro; Torrisi, Maria R; Rodrigues, Inês P; Ramalho, José S; Futter, Clare E; Barral, Duarte C; Seabra, Miguel C

    2014-04-01

    The transfer of melanin from melanocytes to keratinocytes is a crucial process underlying maintenance of skin pigmentation and photoprotection against UV damage. Here, we present evidence supporting coupled exocytosis of the melanin core, or melanocore, by melanocytes and subsequent endocytosis by keratinocytes as a predominant mechanism of melanin transfer. Electron microscopy analysis of human skin samples revealed three lines of evidence supporting this: (1) the presence of melanocores in the extracellular space; (2) within keratinocytes, melanin was surrounded by a single membrane; and (3) this membrane lacked the melanosomal membrane protein tyrosinase-related protein 1 (TYRP1). Moreover, co-culture of melanocytes and keratinocytes suggests that melanin exocytosis is specifically induced by keratinocytes. Furthermore, depletion of Rab11b, but not Rab27a, caused a marked decrease in both keratinocyte-stimulated melanin exocytosis and transfer to keratinocytes. Thus, we propose that the predominant mechanism of melanin transfer is keratinocyte-induced exocytosis, mediated by Rab11b through remodeling of the melanosome membrane, followed by subsequent endocytosis by keratinocytes.

  9. Unlocking the molecular structure of fungal melanin using 13C biosynthetic labeling and solid-state NMR.

    PubMed

    Tian, Shiying; Garcia-Rivera, Javier; Yan, Bin; Casadevall, Arturo; Stark, Ruth E

    2003-07-15

    Melanins are enigmatic pigments found in all biological kingdoms that are associated with a variety of functions, including microbial virulence. Despite being ubiquitous in nature, melanin pigments have long resisted atomic-level structural examination because of their insolubility and amorphous organization. Cryptococcus neoformans is a human pathogenic fungus that melanizes only when provided with exogenous substrate, thus offering a unique system for exploring questions related to melanin structure at the molecular level. We have exploited the requirement for exogenous substrate in melanin synthesis as well as the capabilities of high-resolution solid-state nuclear magnetic resonance (NMR) to establish the predominantly aliphatic composition of l-dopa melanin and to introduce (13)C labels that permit the identification of proximal carbons in the developing biopolymer. By swelling solid melanin samples in organic solvents and using two-dimensional heteronuclear NMR in conjunction with magic-angle spinning, we have identified chemical bonding patterns typical of alkane, alkene, alcohol, ketone, ester, and indole functional groups. These findings demonstrate the feasibility of a novel approach to determining the structure of melanin using metabolic labeling and NMR spectroscopy.

  10. Gamma radiation interacts with melanin to alter its oxidation-reduction potential and results in electric current production.

    PubMed

    Turick, Charles E; Ekechukwu, Amy A; Milliken, Charles E; Casadevall, Arturo; Dadachova, Ekaterina

    2011-08-01

    The presence of melanin pigments in organisms is implicated in radioprotection and in some cases, enhanced growth in the presence of high levels of ionizing radiation. An understanding of this phenomenon will be useful in the design of radioprotective materials. However, the protective mechanism of microbial melanin in ionizing radiation fields has not yet been elucidated. Here we demonstrate through the electrochemical techniques of chronoamperometry, chronopotentiometry and cyclic voltammetry that microbial melanin is continuously oxidized in the presence of gamma radiation. Our findings establish that ionizing radiation interacts with melanin to alter its oxidation-reduction potential. Sustained oxidation resulted in electric current production and was most pronounced in the presence of a reductant, which extended the redox cycling capacity of melanin. This work is the first to establish that gamma radiation alters the oxidation-reduction behavior of melanin, resulting in electric current production. The significance of the work is that it provides the first step in understanding the initial interactions between melanin and ionizing radiation taking place and offers some insight for production of biomimetic radioprotective materials.

  11. Metabolic engineering of Escherichia coli to optimize melanin synthesis from glucose

    PubMed Central

    2013-01-01

    Background Natural aromatic polymers, mainly melanins, have potential and current applications in the cosmetic, pharmaceutical and chemical industries. The biotechnological production of this class of compounds is based on tyrosinase-dependent conversion of L-tyrosine and other aromatic substrates into melanins. The purpose of this work was to apply metabolic engineering for generating Escherichia coli strains with the capacity to synthesize an aromatic polymer from a simple carbon source. Results The strategy was based on the expression in E. coli of the MutmelA gene from Rhizobium etli, encoding an improved mutant tyrosinase. To direct the carbon flow from central metabolism into the common aromatic and the L-tyrosine biosynthetic pathways, feedback inhibition resistant versions of key enzymes were expressed in strains lacking the sugar phosphotransferase system and TyrR repressor. The expressed tyrosinase consumed intracellular L-tyrosine, thus causing growth impairment in the engineered strains. To avoid this issue, a two phase production process was devised, where tyrosinase activity was controlled by the delayed addition of the cofactor Cu. Following this procedure, 3.22 g/L of melanin were produced in 120 h with glucose as carbon source. Analysis of produced melanin by Fourier transform infrared spectroscopy revealed similar characteristics to a pure eumelanin standard. Conclusions This is the first report of a process for producing melanin from a simple carbon source at grams level, having the potential for reducing production cost when compared to technologies employing L-tyrosine as raw material. PMID:24225202

  12. Inhibitory effect of Cinnamomum osmophloeum Kanehira ethanol extracts on melanin synthesis via repression of tyrosinase expression.

    PubMed

    Lee, Shih-Chieh; Chen, Chun-Hao; Yu, Chih-Wen; Chen, Hsiao Ling; Huang, Wei-Tung; Chang, Yun-Shiang; Hung, Shu-Hsien; Lee, Tai-Lin

    2016-09-01

    Melanin contributes to skin color, and tyrosinase is the enzyme that catalyzes the initial steps of melanin formation. Therefore, tyrosinase inhibitors may contribute to the control of skin hyperpigmentation. The inhibition of tyrosinase activity by Cinnamomum zeylanicum extracts was previously reported. In this report, we test the hypothesis that Cinnamomum osmophloeum Kanehira, an endemic plant to Taiwan, contains compounds that inhibit tyrosinase activity, similar to C. zeylanicum. The cytotoxicity of three sources of C. osmophloeum Kanehira ethanol extracts was measured in B16-F10 cells using a methyl thiazolyl tetrazolium bromide (MTT) assay. At concentrations greater than 21.25 μg/mL, the ethanol extracts were toxic to the cells; therefore, 21.25 μg/mL was selected to test the tyrosinase activities. At this concentration, all three ethanol extracts decreased the melanin content by 50% in IBMX-induced B16-F10 cells. In addition to the melanin content, greater than 20% of the tyrosinase activity was inhibited by these ethanol extracts. The RT-PCR results showed that tyrosinase and transcription factor MITF mRNAs expression were down-regulated. Consistent with the mRNA results, greater than 40% of the human tyrosinase promoter activity was inhibited based on the reporter assay. Furthermore, our results demonstrate that the ethanol extracts protect cells from UV exposure. C. osmophloeum Kanehira neutralized the IBMX-induced increase in melanin content in B16-F10 cells by inhibiting tyrosinase gene expression at the level of transcription. Moreover, the ethanol extracts also partially inhibited UV-induced cell damage and prevented cell death. Taken together, we conclude that C. osmophloeum Kanehira is a potential skin-whitening and protective agent.

  13. Melanin-targeted nonlinear microscopy for label-free molecular diagnosis and staining (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Warren, Warren S.

    2017-02-01

    Visible absorption in tissue is dominated by a very small number of chromophores (hemoglobins and melanins) with broad optical spectra; for melanins in particular, the optical absorption spectrum is typically featureless. In addition, scattering limits penetration depth. As a result, the most common microscopy application by far is with excised tissue, which can be stained. However, nonlinear optical methods have the additional advantages of greater penetration depth and reduced sensitivity to scattering. Traditional nonlinear microscopy relies on mechanisms which produce light of a different color than the irradiating lasers, such as second harmonic generation or two photon induced fluorescence, and this contrast is sparse in biological issue without expressing or injecting different chromophores. Recently, stable laser sources and pulse shaping/pulse train modulation methods have made it possible to detect a much wider range of nonlinear molecular signatures, even at modest laser powers (much less than a laser pointer). Here we show the utility of a variety of such signatures (pump-probe, pulse-shaped stimulated Raman, cross-phase modulation) to quantitatively image the biochemical composition of transparent or pigmented tissue in a variety of applications, ranging from thin, unstained tissue sections to live knockout mice. The rich biochemical information provided by this method can be used as an indicator of melanocyte activity, which in turn (for example) reflects the status of melanocytic lesions. Comparisons with model systems (synthetic melanin nanoparticles, sepia melanin) and analysis of melanin degradation pathways in vivo have led to a quantitative understanding of the molecular basis of these changes.

  14. Action spectrum of oxidative reactions mediated by light-activated melanin

    NASA Astrophysics Data System (ADS)

    Glickman, Randolph D.; Rockwell, Benjamin A.; Jacques, Steven L.

    1997-06-01

    The melanin of the retinal pigment epithelial (RPE) cells is generally thought to have a photoprotective role in the eye, yet it is excited by light to a free radical which can react with cellular components. Soluble proteins extracted from the retina are photo-oxidized by the output of a Xenon arc lamp containing UVA and visible wavelengths. The oxidative damage in this model consists of carbonyl adducts to the peptides, and is proportional to the amount of UVA present. Melanosomes isolated from bovine RPE cells and added to the retinal protein extract partly protect the proteins from photo-oxidation resulting from this broadband exposure. However, if the proteins are instead exposed to the 488 and 514.5 nm outputs of an Argon continuous wave laser, the amount of protein oxidation is markedly increased when melanosomes are present. This observation suggests that the melanin free radical is optimally excited by wavelengths in the blue-green region of the visible spectrum, and in fact the action spectrum for the photo-oxidation of NADPH by laser-excited melanin peaks between 450 and 500 nm. The present data do not distinguish between two alternative hypotheses, i.e. that the apparent action spectrum peak is due to (1) a chromophore different from the one determining the overall optical absorption of melanin, or (2) the lower efficiency of UVA photons in activating melanosomes because of their strong absorption at the solution surface. Nevertheless these data implicate melanin in the so-called 'blue light' retinal hazard.

  15. The inhibitory effect of glycolic acid and lactic acid on melanin synthesis in melanoma cells.

    PubMed

    Usuki, Akiko; Ohashi, Akiko; Sato, Hirofumi; Ochiai, Yasunobu; Ichihashi, Masamitsu; Funasaka, Yoko

    2003-01-01

    Alpha-hydroxy acids (AHAs) such as glycolic acid (GA) and lactic acid (LA) have been reported to be effective in treating pigmentary lesions such as melasma, solar lentigines, and postinflammatory hyperpigmentation. The mechanism of this effect might be due to epidermal remodeling and accelerated desquamation, which would result in quick pigment dispersion. However, the direct effect of AHAs on melanin synthesis has not yet been well studied. To elucidate such a direct effect of AHAs on melanogenesis, we performed melanin assays, growth curve determinations, Northern and Western blotting for melanogenic proteins [tyrosinase, tyrosinase related protein (TRP)-1 and TRP-2], and tyrosinase and, 4-dihydroxyphenylalaninechrome tautomerase enzyme activity assays using mouse B16 and human melanoma cells. GA or LA (at doses of 300 or 500 microg/ml) inhibited melanin formation in similar dose-dependent manner, without affecting cell growth. Although the mRNA and protein expression or molecular size of tyrosinase, TRP-1 and TRP-2 were not affected, tyrosinase activity was inhibited. To see whether GA and/or LA directly inhibit tyrosinase catalytic function, the effect of GA and LA on human tyrosinase purified from the melanosome-rich large granule fraction of human melanoma cells was performed. GA or LA were shown to inhibit tyrosinase enzyme activity directly, but this effect was not due to the acidity of GA or LA, because adjusting the pH to 5.6 (the pH of GA and LA at concentrations of 2500 microg/ml), did not affect tyrosinase activity. Taken together, these results show that GA and LA suppress melanin formation by directly inhibiting tyrosinase activity, an effect independent of their acidic nature. GA and LA might work on pigmentary lesions not only by accelerating the turnover of the epidermis but also by directly inhibiting melanin formation in melanocytes.

  16. Characterization of human hair melanin and its degradation products by means of magnetic resonance techniques.

    PubMed

    Ghiani, Simona; Baroni, Simona; Burgio, Daniela; Digilio, Giuseppe; Fukuhara, Masaki; Martino, Paola; Monda, Keiji; Nervi, Carlo; Kiyomine, Akira; Aime, Silvio

    2008-05-01

    Melanin granules (MGs) have been extracted from human Chinese black hairs by either acid hydrolysis (CH-type MGs) or enzymatic digestion (CP-type MGs), and their chemical structure investigated at the solid state by means of (13)C cross polarization magic angle spinning (CPMAS NMR) and EPR spectroscopy. Both types of MGs contain a large amount of protein that is tightly bound to the true melanin polymer, with CP-type MGs having a larger protein content than CH-type ones. Moreover, MGs may also contain variable amounts of lipid-like material. A high amount of paramagnetic metals is detected by EPR in CP-type MGs, in particular Fe(III). Iron can be bound in two chemical forms: as isolated high spin Fe(III) ions with rhombic symmetry and as small oxy-hydroxy Fe(III) aggregates. Iron is poorly available to chelators. CH-type MGs contain much fewer metals. CP-type MGs have then been subjected to partial bleaching by hydrogen peroxide in ammonia, yielding a residual solid, called residual oxidized melanin (ROM) and a soluble but still pigmented fraction called melanin free acid (MFA). MFA can be isolated by precipitation at acidic pH. The (13)C-CPMAS NMR and EPR spectra of these derivatives indicated that ROM has a structure very similar to that of parent MGs, whereas MFA shows a decrease of the protein content with respect to the melanin and a decreased amount of bound iron. Thus, the oxidative degradation of CP-type MGs is a process not involving the bulk of MGs, but rather it proceeds from the solvent-exposed outer parts to the interior. Copyright (c) 2008 John Wiley & Sons, Ltd.

  17. Melanin directly converts light for vertebrate metabolic use: heuristic thoughts on birds, Icarus and dark human skin.

    PubMed

    Goodman, Geoffrey; Bercovich, Dani

    2008-08-01

    Pigments serve many visually obvious animal functions (e.g. hair, skin, eyes, feathers, scales). One is 'melanin', unusual in an absorption across the UV-visual spectrum which is controversial. Any polymer or macro-structure of melanin monomers is 'melanin'. Its roles derive from complex structural and physical-chemical properties e.g. semiconductor, stable radical, conductor, free radical scavenger, charge-transfer. Clinicians and researchers are well acquainted with melanin in skin and ocular pathologies and now increasingly are with internal, melanized, pathology-associated sites not obviously subject to light radiation (e.g. brain, cochlea). At both types of sites some findings puzzle: positive and negative neuromelanin effects in Parkinsons; unexpected melanocyte action in the cochlea, in deafness; melanin reduces DNA damage, but can promote melanoma; in melanotic cells, mitochondrial number was 83% less, respiration down 30%, but development similar to normal amelanotic cells. A little known, avian anatomical conundrum may help resolve melanin paradoxes. One of many unique adaptations to flight, the pecten, strange intra-ocular organ with unresolved function(s), is much enlarged and heavily melanized in birds fighting gravity, hypoxia, thirst and hunger during long-distance, frequently sub-zero, non-stop migration. The pecten may help cope with energy and nutrient needs under extreme conditions, by a marginal but critical, melanin-initiated conversion of light to metabolic energy, coupled to local metabolite recycling. Similarly in Central Africa, reduction in body hair and melanin increase may also have lead to 'photomelanometabolism' which, though small scale/ unit body area, in total may have enabled a sharply increased development of the energy-hungry cortex and enhanced human survival generally. Animal inability to utilize light energy directly has been traditionally assumed. Melanin and the pecten may have unexpected lessons also for human physiology

  18. Selective antiviral activity of synthetic soluble L-tyrosine and L-dopa melanins against human immunodeficiency virus in vitro.

    PubMed

    Montefiori, D C; Zhou, J Y

    1991-01-01

    Melanins are pigments found in hair, skin, irides of the eye, and brain. Their functions in mammals include protection from exposure to sunlight, camouflage from predators, sexual recognition within species, and possible electron transfer reactants. Most natural melanins exist in an insoluble form, which is one reason there is little information on the biological properties of soluble melanins. Here, synthetic soluble melanins were obtained by chemical oxidation of L-tyrosine or spontaneous oxidation of L-beta-3,4-dihydroxyphenylalanine (L-dopa). Replication of human immunodeficiency virus types 1 and 2 (HIV-1 and HIV-2) was inhibited by soluble melanin in two human lymphoblastoid cell lines (MT-2 and H9) and in phytohemagglutinin-stimulated human T cells. Effective concentrations of 0.15-10 micrograms/ml had no cell toxicity. Melanin blocked infection by cell-free virus and interfered with HIV-induced syncytium formation and cytopathic effects when fusion-susceptible, uninfected cells, were mixed with chronically infected cells. Melanin also impeded the HIV-1 envelope surface glycoprotein, and T cell specific monoclonal antibody leu-3a (CD4), but not leu-5b (CD2), from binding to the surface of MT-2 cells. No effect on HIV-1 reverse transcriptase activity in viral lysates was observed. These results identify a unique biological property of melanin, and suggest that soluble melanins may represent a new class of pharmacologically active substances which should be further investigated for potential therapeutic utility in the treatment of Acquired Immune Deficiency Syndrome (AIDS).

  19. Following fungal melanin biosynthesis with solid-state NMR: biopolymer molecular structures and possible connections to cell-wall polysaccharides.

    PubMed

    Zhong, Junyan; Frases, Susana; Wang, Hsin; Casadevall, Arturo; Stark, Ruth E

    2008-04-22

    Melanins serve a variety of protective functions in plants and animals, but in fungi such as Cryptococcus neoformans they are also associated with virulence. A recently developed solid-state nuclear magnetic resonance (NMR) strategy, based on the incorporation of site-specific (13)C-enriched precursors into melanin, followed by spectroscopy of both powdered and solvent-swelled melanin ghosts, was used to provide new molecular-level insights into fungal melanin biosynthesis. The side chain of an l-dopa precursor was shown to cyclize and form a proposed indole structure in C. neoformans melanin, and modification of the aromatic rings revealed possible patterns of polymer chain elongation and cross-linking within the biopolymer. Mannose supplied in the growth medium was retained as a beta-pyranose moiety in the melanin ghosts even after exhaustive degradative and dialysis treatments, suggesting the possibility of tight binding or covalent incorporation of the pigment into the polysaccharide fungal cell walls. In contrast, glucose was scrambled metabolically and incorporated into both polysaccharide cell walls and aliphatic chains present in the melanin ghosts, consistent with metabolic use as a cellular nutrient as well as covalent attachment to the pigment. The prominent aliphatic groups reported previously in several fungal melanins were identified as triglyceride structures that may have one or more sites of chain unsaturation. These results establish that fungal melanin contains chemical components derived from sources other than l-dopa polymerization and suggest that covalent linkages between l-dopa-derived products and polysaccharide components may serve to attach this pigment to cell wall structures.

  20. Pigmented epidermal cyst with dense collection of melanin: A rare entity - Report of a case with review of the literature.

    PubMed

    Jayalakshmy, P S; Subitha, K; Priya, P V; Johnson, Gerald

    2012-05-01

    Epidermal cyst is a very common benign cystic lesion of the skin. It is usual to find ulceration of the lining epithelium, rupture of the cyst wall with chronic inflammation and foreign body giant cell reaction. But, it is very rare to see an epidermal cyst with marked accumulation of melanin pigment. Only a few cases of pigmented epidermal cyst with dense collection of melanin pigment have been published in the literature. Here, we are reporting a case of ruptured epidermal cyst with keratin granuloma formation and showing dense collection of melanin pigment.

  1. In vivo isolation of the effects of melanin from underlying hemodynamics across skin types using spatial frequency domain spectroscopy

    NASA Astrophysics Data System (ADS)

    Saager, Rolf B.; Sharif, Ata; Kelly, Kristen M.; Durkin, Anthony J.

    2016-05-01

    Skin is a highly structured tissue, raising concerns as to whether skin pigmentation due to epidermal melanin may confound accurate measurements of underlying hemodynamics. Using both venous and arterial cuff occlusions as a means of inducing differential hemodynamic perturbations, we present analyses of spectra limited to the visible or near-infrared regime, in addition to a layered model approach. The influence of melanin, spanning Fitzpatrick skin types I to V, on underlying estimations of hemodynamics in skin as interpreted by these spectral regions are assessed. The layered model provides minimal cross-talk between melanin and hemodynamics and enables removal of problematic correlations between measured tissue oxygenation estimates and skin phototype.

  2. Morpho-histology of head kidney of female catfish Heteropneustes fossilis: seasonal variations in melano-macrophage centers, melanin contents and effects of lipopolysaccharide and dexamethasone on melanins.

    PubMed

    Kumar, Ravi; Joy, K P; Singh, S M

    2016-10-01

    In the catfish Heteropneustes fossilis, the anterior kidney is a hemopoietic tissue which surrounds the adrenal homologues, interrenal (IR) and chromaffin tissues corresponding to the adrenal cortical and adrenal medulla of higher mammals. The IR tissue is arranged in cell cords around the posterior cardinal vein (PCV) and its tributaries and secretes corticosteroids. The chromaffin tissue is scattered singly or in nests of one or more cells around the epithelial lining of the PCV or blood capillaries within the IR tissue. They are ferric ferricyanide-positive. Leukemia-inhibitory factor (LIF)-like reactivity was noticed in the lining of the epithelium of the IR cell cords and around the wall of the PCV and blood capillaries. No staining was observed in the hemopoietic cells. IL-1β- and TNF-α-like immunoreactivity was seen in certain cells in the hemopoietic tissue but not in the IR region. Macrophages were identified with mammalian macrophage-specific MAC387 antibodies and are present in the hemopoietic mass but not in the IR tissue. Pigments accumulate in the hemopoietic mass as melano-macrophage centers (MMCs) and are PAS-, Schmorl's- and Perls'-positive. The pigments contain melanin (black), hemosiderin (blue) and lipofuscin/ceroid (oxidized lipid, yellowish tan), as evident from the Perls' reaction. The MMCs were TUNEL-positive as evident from FITC fluorescence, indicating their apoptotic nature. The MMCs showed significant seasonal variation with their density increasing to the peak in the postspawning phase. Melanins were characterized spectrophotometrically for the first time in fish anterior kidney. The predominant form is pheomelanin (PM), followed by eumelanin (EM) and alkali-soluble melanin (ASM). Melanins showed significant seasonal variations with the level low in the resting phase and increasing to the peak in the postspawning phase. Under in vitro conditions, lipopolysaccharide (10 µg/mL) treatment increased significantly the levels of PM and EM

  3. A thioredoxin of Sinorhizobium meliloti CE52G is required for melanin production and symbiotic nitrogen fixation.

    PubMed

    Castro-Sowinski, Susana; Matan, Ofra; Bonafede, Paula; Okon, Yaacov

    2007-08-01

    A miniTn5-induced mutant of a melanin-producing strain of Sinorhizobium meliloti (CE52G) that does not produce melanin was mapped to a gene identified as a probable thioredoxin gene. It was proved that the thiol-reducing activity of the mutant was affected. Addition to the growth medium of substrates that induce the production of melanin (L-tyrosine, guaiacol, orcinol) increased the thioredoxin-like (trxL) mRNA level in the wild-type strain. The mutant strain was affected in the response to paraquat-induced oxidative stress, symbiotic nitrogen fixation, and both laccase and tyrosinase activities. The importance of thioredoxin in melanin production in bacteria, through the regulation of laccase or tyrosinase activities, or both, by the redox state of structural or catalytic SH groups, is discussed.

  4. Amikacin, kanamycin and tobramycin binding to melanin in the presence of Ca(2+) and Mg(2+) ions.

    PubMed

    Wrześniok, Dorota; Buszman, Ewa; Miernik-Biela, Ewa

    2012-01-01

    The aim of the presented work was to examine the interaction of amikacin, kanamycin and tobramycin with melanin in the presence of Ca(2+ )and Mg(2+) ions. It has been demonstrated that the analyzed aminoglycosides form complexes with melanin in the presence of metal ions and the amount of drugs bound to the polymer increases with increasing initial antibiotics concentration. It has been also shown that two classes of binding sites participate in the formation of amikacin, kanamycin and tobramycin complexes with melanin containing Ca(2+) or Mg(2+) ions: high affinity binding sites (n1) with the association constant K1 approximately 10(4)-10(5)M(-1) and low affinity binding sites (n2) with K2 approximately 10(3)M(-1). It has been demonstrated that calcium and magnesium significantly decrease the number of total binding sites (ntot) as compared with aminoglycoside-melanin complexes obtained in the absence of metal ions.

  5. EPR characteristics of free radicals in DOPA-melanin-moxifloxacin complexes at ambient level of UVA radiation

    NASA Astrophysics Data System (ADS)

    Beberok, Artur; Zdybel, Magdalena; Pilawa, Barbara; Buszman, Ewa; Wrześniok, Dorota

    2014-01-01

    EPR studies pointed out that o-semiquinone free radicals with g-values 2.0038-2.0040 take part in moxifloxacin-melanin complex formation. The process contributed to increase in free radicals concentration in nonirradiated complexes. This effect was observed for the complexes with 1 × 10-4 M, 1 × 10-3 M and 4 × 10-3 M drug concentrations. UV irradiation contributed to decrease in free radicals concentration in DOPA-melanin complexes with moxifloxacin, besides the complexes with the drug concentration of 1 × 10-4 M. The strongest decrease was observed for DOPA-melanin-moxifloxacin complexes with the drug concentration of 1 × 10-3 M. Homogeneous broadening of EPR lines, strong dipolar interactions and slow spin-lattice relaxation processes characterized all the tested melanin samples.

  6. Loss of Melanin by Eye Retinal Pigment Epithelium Cells Is Associated with Its Oxidative Destruction in Melanolipofuscin Granules.

    PubMed

    Dontsov, A E; Sakina, N L; Ostrovsky, M A

    2017-08-01

    The effect of superoxide radicals on melanin destruction and degradation of melanosomes isolated from cells of retinal pigment epithelium (RPE) of the human eye was studied. We found that potassium superoxide causes destruction of melanin in melanosomes of human and bovine RPE, as well as destruction of melanin from the ink bag of squid, with the formation of fluorescent decay products having an emission maximum at 520-525 nm. The initial kinetics of the accumulation of the fluorescent decay products is linear. Superoxide radicals lead simultaneously to a decrease in the number of melanosomes and to a decrease in concentration of paramagnetic centers in them. Complete degradation of melanosomes leads to the formation of a transparent solution containing dissolved proteins and melanin degradation products that do not exhibit paramagnetic properties. To completely degrade one melanosome of human RPE, 650 ± 100 fmol of superoxide are sufficient. The concentration of paramagnetic centers in a melanolipofuscin granule of human RPE is on average 32.5 ± 10.4% (p < 0.05, 150 eyes) lower than in a melanosome, which indicates melanin undergoing a destruction process in these granules. RPE cells also contain intermediate granules that have an EPR signal with a lower intensity than that of melanolipofuscin granules, but higher than that of lipofuscin granules. This signal is due to the presence of residual melanin in these granules. Irradiation of a mixture of melanosomes with lipofuscin granules with blue light (450 nm), in contrast to irradiation of only melanosomes, results in the appearance of fluorescent melanin degradation products. We suggest that one of the main mechanisms of age-related decrease in melanin concentration in human RPE cells is its destruction in melanolipofuscin granules under the action of superoxide radicals formed during photoinduced oxygen reduction by lipofuscin fluorophores.

  7. Quantitation of in vitro α-1 adrenergic receptor antagonist binding capacity to biologic melanin using tandem mass spectrometry.

    PubMed

    Gaynes, Jeffrey S; Micic, Cedomir; Gaynes, Bruce I; Borgia, Jeffrey A

    2013-12-01

    The purpose of this study was to develop methods to allow evaluation of the binding characteristics for a series of α-1 antagonists to biologically-derived melanin. Fresh bovine globes were used to obtain iridal and choroid/retinal pigment epithelial (CRPE) derived melanin. Binding characteristics of chloroquine, tamsulosin and doxazosin were then evaluated in vitro using tandem mass spectroscopy. Tandem mass spectrometry-based assays were developed for three α-1 antagonists that provided linear assay ranges which spanned (minimally) 0.01-10 µg/mL, while exhibiting excellent inter-assay precision and accuracy. When applied to the evaluation of binding characteristics for iridal melanin, mean chloroquine and tamsulosin fractions were found to be 41.9 ± 14.2 pmoles mg(-1) and 25.34 ± 6.186 pmoles mg(-1), respectively. Mean iridal doxazosin binding was found to be 6.36 ± 2.19 pmoles mg(-1). Interestingly, mean levels of tamsulosin, but not doxazosin found bound to choroid/CRPE derived melanin approached that of chloroquine (27.91 µg/mL, 25.68 µg/mL and 5.94 µg/mL for chloroquine, tamsulosin and doxazosin, respectively). One way ANOVA for binding affinity for chloroquine, tamsulosin and doxazosin was statistically significant for both iridal and CRPE-derived melanin (p = 0.0012 and 0.0023), respectively. A Bonferroni post-hoc analysis demonstrated a statistically significant difference in the amount of binding between tamsulosin, doxazosin and chloroquine to iridal but not CRPE derived melanin (p < 0.05). Tamsulosin appears to demonstrate melanin binding affinity which approaches chloroquine and exceeds doxazosin for both iridal and CRPE-derived bovine melanin.

  8. [THE INFLUENCE OF MELANIN ON THE GASTRIC MUCOSA AND HYPOTHALAMIC-PITUITARY-ADRENOCORTICAL AXIS UNDER ACUTE STRESS CONDITIONS].

    PubMed

    Golyshkin, D V; Falalyeyeva, T M; Neporada, K S; Beregova, T V

    2015-01-01

    We studied the influence of melanin from yeast-like fungi Nadsoniella nigra strain X1 on the changes of the levels of adrenocorticotropic hormone (ACTH) and cortisol in blood serum of rats, adrenal glands weight ratio and lesions of the gastric mucosa (GM) caused by neuromuscular tension by Selye. Melanin administration restored functioning of the hypothalamic-pituitary-adrenal axis that was evident by an increase of ACTH concentration by 42% and a decrease of cortisol concentration by 19% compared to the rats injected with water (group 2). In rats treated with melanin, the adrenal glands weight ratio, didn't differ from intact control group of the rats. Melanin decreased ulcers area by 64% and reduced the content of free hydroxyproline by 29%, the free fucose by 16% and the free hexuronic acids by 24% in the GM compared to the group 2 of the rats. It is established that the mechanism of melanin stress-protective properties are based on its regulation of the glucocorticoids secretion and prevention of GM collagen and extracellular matrix substances depolymerization. Melanin possesses gastroprotective properties and is a perspective agent for preventing and treatment of consequences of the stress influence on the organism.

  9. Compton scattering by internal shields based on melanin-containing mushrooms provides protection of gastrointestinal tract from ionizing radiation.

    PubMed

    Revskaya, Ekaterina; Chu, Peter; Howell, Robertha C; Schweitzer, Andrew D; Bryan, Ruth A; Harris, Matthew; Gerfen, Gary; Jiang, Zewei; Jandl, Thomas; Kim, Kami; Ting, Li-Min; Sellers, Rani S; Dadachova, Ekaterina; Casadevall, Arturo

    2012-11-01

    There is a need for radioprotectors that protect normal tissues from ionizing radiation in patients receiving high doses of radiation and during nuclear emergencies. We investigated the possibility of creating an efficient oral radioprotector based on the natural pigment melanin that would act as an internal shield and protect the tissues via Compton scattering followed by free radical scavenging. CD-1 mice were fed melanin-containing black edible mushrooms Auricularia auricila-judae before 9 Gy total body irradiation. The location of the mushrooms in the body before irradiation was determined by in vivo fluorescent imaging. Black mushrooms protected 80% of mice from the lethal dose, while control mice or those given melanin-devoid mushrooms died from gastrointestinal syndrome. The crypts of mice given black mushrooms showed less apoptosis and more cell division than those in control mice, and their white blood cell and platelet counts were restored at 45 days to preradiation levels. The role of melanin in radioprotection was proven by the fact that mice given white mushrooms supplemented with melanin survived at the same rate as mice given black mushrooms. The ability of melanin-containing mushrooms to provide remarkable protection against radiation suggests that they could be developed into oral radioprotectors.

  10. Compton Scattering by Internal Shields Based on Melanin-Containing Mushrooms Provides Protection of Gastrointestinal Tract from Ionizing Radiation

    PubMed Central

    Revskaya, Ekaterina; Chu, Peter; Howell, Robertha C.; Schweitzer, Andrew D.; Bryan, Ruth A.; Harris, Matthew; Gerfen, Gary; Jiang, Zewei; Jandl, Thomas; Kim, Kami; Ting, Li-Min; Sellers, Rani S.; Casadevall, Arturo

    2012-01-01

    Abstract There is a need for radioprotectors that protect normal tissues from ionizing radiation in patients receiving high doses of radiation and during nuclear emergencies. We investigated the possibility of creating an efficient oral radioprotector based on the natural pigment melanin that would act as an internal shield and protect the tissues via Compton scattering followed by free radical scavenging. CD-1 mice were fed melanin-containing black edible mushrooms Auricularia auricila-judae before 9 Gy total body irradiation. The location of the mushrooms in the body before irradiation was determined by in vivo fluorescent imaging. Black mushrooms protected 80% of mice from the lethal dose, while control mice or those given melanin-devoid mushrooms died from gastrointestinal syndrome. The crypts of mice given black mushrooms showed less apoptosis and more cell division than those in control mice, and their white blood cell and platelet counts were restored at 45 days to preradiation levels. The role of melanin in radioprotection was proven by the fact that mice given white mushrooms supplemented with melanin survived at the same rate as mice given black mushrooms. The ability of melanin-containing mushrooms to provide remarkable protection against radiation suggests that they could be developed into oral radioprotectors. PMID:23113595

  11. Statistical analysis on activation and photo-bleaching of step-wise multi-photon activation fluorescence of melanin

    NASA Astrophysics Data System (ADS)

    Gu, Zetong; Lai, Zhenhua; Zhang, Xi; Yin, Jihao; DiMarzio, Charles A.

    2015-03-01

    Melanin is regarded as the most enigmatic pigments/biopolymers found in most organisms. We have shown previously that melanin goes through a step-wise multi-photon absorption process after the fluorescence has been activated with high laser intensity. No melanin step-wise multi-photon activation fluorescence (SMPAF) can be obtained without the activation process. The step-wise multi-photon activation fluorescence has been observed to require less laser power than what would be expected from a non-linear optical process. In this paper, we examined the power dependence of the activation process of melanin SMPAF at 830nm and 920nm wavelengths. We have conducted research using varying the laser power to activate the melanin in a point-scanning mode for multi-photon microscopy. We recorded the fluorescence signals and position. A sequence of experiments indicates the relationship of activation to power, energy and time so that we can optimize the power level. Also we explored regional analysis of melanin to study the spatial relationship in SMPAF and define three types of regions which exhibit differences in the activation process.

  12. Compositional changes of human hair melanin resulting from bleach treatment investigated by nanoscale secondary ion mass spectrometry.

    PubMed

    Kojima, Toru; Yamada, Hiromi; Isobe, Mitsuru; Yamamoto, Toshihiko; Takeuchi, Miyuki; Aoki, Dan; Matsushita, Yasuyuki; Fukushima, Kazuhiko

    2014-11-01

    It is important to understand the influence of bleach treatment on human hair because it is one of the most important chemical treatments in hair cosmetic processes. A comparison of the elemental composition of melanin between virgin hair and bleached hair would provide important information about the structural changes of melanin. To investigate the elemental composition of melanin granules in virgin black hair and bleached hair, these hair cross-sections are analyzed by using a nanoscale secondary ion mass spectrometry (NanoSIMS). The virgin black hair and bleached hair samples were embedded in resin and smooth hair cross-sections were obtained using an ultramicrotome. NanoSIMS measurements were performed using a Cs(+) primary ion beam to detect negative secondary ions. More intensive (16) O(-) ions were detected from the melanin granules of bleached hair than from those of virgin black hair in NanoSIMS (16) O(-) ion image. In addition, it was indicated that (16) O(-) ion intensity and (16) O(-) /(12) C(14) N(-) ion intensity ratio of melanin granules in bleached hair were higher than those in virgin black hair. Nanoscale secondary ion mass spectrometry analysis of the cross-sections of virgin black hair and bleached hair indicated that the oxygen content in melanin granules was increased by bleach treatment. © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  13. Marine hydroid perisarc: a chitin- and melanin-reinforced composite with DOPA-iron(III) complexes.

    PubMed

    Hwang, Dong Soo; Masic, Admir; Prajatelistia, Ekavianty; Iordachescu, Mihaela; Waite, J Herbert

    2013-09-01

    Many marine invertebrates utilize biomacromolecules as building blocks to form their load-bearing tissues. These polymeric tissues are appealing for their unusual physical and mechanical properties, including high hardness and stiffness, toughness and low density. Here, a marine hydroid perisarc of Aglaophenia latirostris was investigated to understand how nature designs a stiff, tough and lightweight sheathing structure. Chitin, protein and a melanin-like pigment, were found to represent 10, 17 and 60 wt.% of the perisarc, respectively. Interestingly, similar to the adhesive and coating of marine mussel byssus, a DOPA (3,4-dihydroxyphenylalanine) containing protein and iron were detected in the perisarc. Resonance Raman microprobe analysis of perisarc indicates the presence of catechol-iron(III) complexes in situ, but it remains to be determined whether the DOPA-iron(III) interaction plays a cohesive role in holding the protein, chitin and melanin networks together.

  14. Melanin Photosensitization and the Effect of Visible Light on Epithelial Cells

    PubMed Central

    Chiarelli-Neto, Orlando; Ferreira, Alan Silva; Martins, Waleska Kerllen; Pavani, Christiane; Severino, Divinomar; Faião-Flores, Fernanda; Maria-Engler, Silvya Stuchi; Aliprandini, Eduardo; Martinez, Glaucia R.; Di Mascio, Paolo; Medeiros, Marisa H. G.; Baptista, Maurício S.

    2014-01-01

    Protecting human skin from sun exposure is a complex issue that involves unclear aspects of the interaction between light and tissue. A persistent misconception is that visible light is safe for the skin, although several lines of evidence suggest otherwise. Here, we show that visible light can damage melanocytes through melanin photosensitization and singlet oxygen (1O2) generation, thus decreasing cell viability, increasing membrane permeability, and causing both DNA photo-oxidation and necro-apoptotic cell death. UVA (355 nm) and visible (532 nm) light photosensitize 1O2 with similar yields, and pheomelanin is more efficient than eumelanin at generating 1O2 and resisting photobleaching. Although melanin can protect against the cellular damage induced by UVB, exposure to visible light leads to pre-mutagenic DNA lesions (i.e., Fpg- and Endo III-sensitive modifications); these DNA lesions may be mutagenic and may cause photoaging, as well as other health problems, such as skin cancer. PMID:25405352

  15. Macular pigment, photopigments, and melanin: distributions in young subjects determined by four-wavelength reflectometry

    PubMed Central

    Bone, Richard A.; Brener, Betty; Gibert, Jorge C.

    2007-01-01

    We have developed an objective procedure, using a modified retinal camera, to determine macular pigment (MP) optical density distributions in the human retina. Using two multi-band filters, reflectance maps of the retinas of young subjects (<25 years old) were obtained at 460, 528, 610 and 670 nm, without pupil dilation. The log-transformed maps were combined linearly to yield optical density maps of MP, cone and rod photopigments, and melanin. MP optical density and heterochromatic flicker photometry results for 22 subjects were in reasonable agreement. Cone photopigments, like MP, showed similar, well-defined peaks at the fovea, whereas rod photopigment showed a minimum. Melanin was more broadly distributed. PMID:17937965

  16. Melanoma induction by ultraviolet A but not ultraviolet B radiation requires melanin pigment.

    PubMed

    Noonan, Frances P; Zaidi, M Raza; Wolnicka-Glubisz, Agnieszka; Anver, Miriam R; Bahn, Jesse; Wielgus, Albert; Cadet, Jean; Douki, Thierry; Mouret, Stephane; Tucker, Margaret A; Popratiloff, Anastas; Merlino, Glenn; De Fabo, Edward C

    2012-06-06

    Malignant melanoma of the skin (CMM) is associated with ultraviolet radiation exposure, but the mechanisms and even the wavelengths responsible are unclear. Here we use a mammalian model to investigate melanoma formed in response to precise spectrally defined ultraviolet wavelengths and biologically relevant doses. We show that melanoma induction by ultraviolet A (320-400 nm) requires the presence of melanin pigment and is associated with oxidative DNA damage within melanocytes. In contrast, ultraviolet B radiation (280-320 nm) initiates melanoma in a pigment-independent manner associated with direct ultraviolet B DNA damage. Thus, we identified two ultraviolet wavelength-dependent pathways for the induction of CMM and describe an unexpected and significant role for melanin within the melanocyte in melanomagenesis.

  17. Scopoletin from Cirsium setidens Increases Melanin Synthesis via CREB Phosphorylation in B16F10 Cells.

    PubMed

    Ahn, Mi-Ja; Hur, Sun-Jung; Kim, Eun-Hyun; Lee, Seung Hoon; Shin, Jun Seob; Kim, Myo-Kyoung; Uchizono, James A; Whang, Wan-Kyunn; Kim, Dong-Seok

    2014-08-01

    In this study, we isolated scopoletin from Cirsium setidens Nakai (Compositae) and tested its effects on melanogenesis. Scopoletin was not toxic to cells at concentrations less than 50 µM and increased melanin synthesis in a dose-dependent manner. As melanin synthesis increased, scopoletin stimulated the total tyrosinase activity, the rate-limiting enzyme of melanogenesis. In a cell-free system, however, scopoletin did not increase tyrosinase activity, indicating that scopoletin is not a direct activator of tyrosinase. Furthermore, Western blot analysis showed that scopoletin stimulated the production of microphthalmia-associated transcription factor (MITF) and tyrosinase expression via cAMP response element-binding protein (CREB) phosphorylation in a dose-dependent manner. Based on these results, preclinical and clinical studies are needed to assess the use of scopoletin for the treatment of vitiligo.

  18. Scopoletin from Cirsium setidens Increases Melanin Synthesis via CREB Phosphorylation in B16F10 Cells

    PubMed Central

    Ahn, Mi-Ja; Hur, Sun-Jung; Kim, Eun-Hyun; Lee, Seung Hoon; Shin, Jun Seob; Kim, Myo-Kyoung; Uchizono, James A.; Whang, Wan-Kyunn

    2014-01-01

    In this study, we isolated scopoletin from Cirsium setidens Nakai (Compositae) and tested its effects on melanogenesis. Scopoletin was not toxic to cells at concentrations less than 50 µM and increased melanin synthesis in a dose-dependent manner. As melanin synthesis increased, scopoletin stimulated the total tyrosinase activity, the rate-limiting enzyme of melanogenesis. In a cell-free system, however, scopoletin did not increase tyrosinase activity, indicating that scopoletin is not a direct activator of tyrosinase. Furthermore, Western blot analysis showed that scopoletin stimulated the production of microphthalmia-associated transcription factor (MITF) and tyrosinase expression via cAMP response element-binding protein (CREB) phosphorylation in a dose-dependent manner. Based on these results, preclinical and clinical studies are needed to assess the use of scopoletin for the treatment of vitiligo. PMID:25177162

  19. Melanin- and carotenoid-dependent signals of great tits (Parus major) relate differently to metal pollution.

    PubMed

    Dauwe, Tom; Eens, Marcel

    2008-10-01

    Due to their high phenotypic plasticity, the expression of secondary sexual characteristics is particularly sensitive to stress. Here, we investigated the expression of two conspicuous visual signals in great tits (Parus major) in a metal pollution gradient. In three study sites with marked differences in metal contamination (mainly lead, cadmium, copper and zinc), we compared melanin and carotenoid colouration of great tits. While carotenoid colouration (yellow breast) was negatively related to metal pollution, the size of a melanin trait (breast stripe) was larger in the most polluted sites. Environmental pollutants not only affect the expression of conspicuous signals but may even enhance, directly or indirectly, a signal of male quality such as breast stripe. Our results also support the multiple messages hypothesis predicting that different signals highlight different aspects of geno- and phenotypic condition of the bearer.

  20. [The magnetic susceptibility of the melanin in the eyes of representatives of different vertebrate classes].

    PubMed

    Zagal'skaia, E O

    1995-01-01

    The magnetoperceptivity (Chi) and element composition of eye pigment epitelium (EPE) melanin in vertebrate animals were measured. The minimal values of EPE Chi were found in winter-sleeping and anabiotic animals (Ursus arctos, Rana temporaria). The magnetoperception was high in migrating animals (Oncorhynchus keta, 0. gorbuscha, Anas crecca) and in wild gray rats as well, EPE magnetoperceptivity in albino rats wasn't practicaly established. In the majority of cases the quantity of magnetoperceptivity correlates with per-cent content of iron. The evident correlation between melanin magnet properties and the life strategy of the investigated animals allows to propose the participance of eye pigment epithelium in orientation and navigation of the animals.

  1. Role of thiol compounds in mammalian melanin pigmentation: Part I. Reduced and oxidized glutathione.

    PubMed

    Benedetto, J P; Ortonne, J P; Voulot, C; Khatchadourian, C; Prota, G; Thivolet, J

    1981-11-01

    Evidence for the postulated role of glutathione reductase in melanin pigmentation has been obtained by determinations of the glutathione concentrations in Tortoiseshell guinea pig skin of different colors (black, yellow, red, and white). As expected, the lowest levels of reduced glutathione (GSH) were found associated with eumelanin type pigmentation, whereas the highest ones were found in the skin with phaeomelanin producing melanocytes. On the other hand, white skin of guinea pig having no active melanocytes showed GSH levels which were intermediate between those of the black and yellow areas. These results are consistent with the view that the activity of the enzyme glutathione reductase, though not primarily related to pigmentation, plays an important role in the regulation and control of the biosynthetic activity of melanocytes leading to various types of melanin pigments.

  2. Remittance at a single wavelength of 390 nm to quantify epidermal melanin concentration

    PubMed Central

    Verkruysse, Wim; Svaasand, Lars O.; Franco, Walfre; Nelson, J. Stuart

    2009-01-01

    Objective quantification of epidermal melanin concentration (EMC) should be useful in laser dermatology to determine the individual maximum safe radiant exposure (IMSRE). We propose a single-wavelength remittance measurement at 390 nm as an alternative optical method to determine EMC and IMSRE. Remittance spectra (360 to 740 nm), melanin index (MI) measurements and the transient radiometric temperature increase, ΔT(t), upon skin irradiation with an Alexandrite laser (755 nm, 3-ms pulse duration, 6 J/cm2) were measured on 749 skin spots (arm and calf) on 23 volunteers (skin phototypes I to IV). Due to the shallow penetration depth and independence of blood oxygen saturation (isosbestic point), remittance at 390 nm appears to provide better estimates for EMC and IMSRE than MI. PMID:19256693

  3. Melanoma induction by ultraviolet A but not ultraviolet B radiation requires melanin pigment

    PubMed Central

    Noonan, Frances P.; Zaidi, M. Raza; Wolnicka-Glubisz, Agnieszka; Anver, Miriam R.; Bahn, Jesse; Wielgus, Albert; Cadet, Jean; Douki, Thierry; Mouret, Stephane; Tucker, Margaret A.; Popratiloff, Anastas; Merlino, Glenn; De Fabo, Edward C.

    2012-01-01

    Malignant melanoma of the skin (CMM) is associated with ultraviolet radiation exposure, but the mechanisms and even the wavelengths responsible are unclear. Here we use a mammalian model to investigate melanoma formed in response to precise spectrally defined ultraviolet wavelengths and biologically relevant doses. We show that melanoma induction by ultraviolet A (320–400 nm) requires the presence of melanin pigment and is associated with oxidative DNA damage within melanocytes. In contrast, ultraviolet B radiation (280–320 nm) initiates melanoma in a pigment-independent manner associated with direct ultraviolet B DNA damage. Thus, we identified two ultraviolet wavelength-dependent pathways for the induction of CMM and describe an unexpected and significant role for melanin within the melanocyte in melanomagenesis. PMID:22673911

  4. Melanin- and carotenoid-dependent signals of great tits ( Parus major) relate differently to metal pollution

    NASA Astrophysics Data System (ADS)

    Dauwe, Tom; Eens, Marcel

    2008-10-01

    Due to their high phenotypic plasticity, the expression of secondary sexual characteristics is particularly sensitive to stress. Here, we investigated the expression of two conspicuous visual signals in great tits ( Parus major) in a metal pollution gradient. In three study sites with marked differences in metal contamination (mainly lead, cadmium, copper and zinc), we compared melanin and carotenoid colouration of great tits. While carotenoid colouration (yellow breast) was negatively related to metal pollution, the size of a melanin trait (breast stripe) was larger in the most polluted sites. Environmental pollutants not only affect the expression of conspicuous signals but may even enhance, directly or indirectly, a signal of male quality such as breast stripe. Our results also support the multiple messages hypothesis predicting that different signals highlight different aspects of geno- and phenotypic condition of the bearer.

  5. Endothelin-1 increases melanin synthesis in an established sheep skin melanocyte culture.

    PubMed

    Pang, Yamiao; Geng, Jianjun; Qin, Yilong; Wang, Haidong; Fan, Ruiwen; Zhang, Ying; Li, Hongquan; Jiang, Shan; Dong, Changsheng

    2016-08-01

    The aims of the study were to establish a culture system for sheep skin melanocytes and uncover the effects of endothelin-1 on melanin synthesis in cultured melanocytes in order to provide an optimal cell system and a theoretical basis for studying the regulatory mechanism of coat color in sheep. In this study, skin punch biopsies were harvested from the dorsal region of 1-3-yr-old sheep, and skin melanocytes were then obtained by the two-step digestion using dispase II and trypsin/ethylene diamine tetraacetic acid (EDTA). The primary cultures of the melanocytes were established and characterized by dopa-staining, immunocytochemical localization of melanocyte markers, and RT-polymerase chain reaction (PCR) analysis of coat color genes. To determine the effect of endothelin-1 on proliferation and melanin synthesis of melanocytes, the cultured cells were treated with different doses of endothelin-1 (10(-7), 10(-8), 10(-9), 10(-10), and 0 mol/L), and the growth rate of melanocytes, production of melanin, expression of related genes, and location of related protein in cultured cells were examined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT), ultraviolet spectrophotometry, qRT-PCR, and immunocytochemical localization, respectively. The results showed that the established melanocyte culture functions properly. Endothelin-1 treatment increased markedly the number of melanocytes and melanin content. In responding to this treatment, expressions of microphthalmia-associated transcription factor (MITF), melanocortin 1 receptor (MC1R), tyrosinase (TYR), and endothelin receptor B (EDNRB) in the melanocytes were significantly up regulated (P < 0.05). Immunocytochemical localization revealed that TYR was mainly localized in the cytoplasm. Positive staining of TYR in the melanocytes was significant. The findings demonstrated that the culture system of sheep skin melanocytes was established successfully in vitro, and endothelin-1 promotes the

  6. Melanocytes and melanin represent a first line of innate immunity against Candida albicans.

    PubMed

    Tapia, Cecilia V; Falconer, Maryanne; Tempio, Fabián; Falcón, Felipe; López, Mercedes; Fuentes, Marisol; Alburquenque, Claudio; Amaro, José; Bucarey, Sergio A; Di Nardo, Anna

    2014-07-01

    Melanocytes are dendritic cells located in the skin and mucosae that synthesize melanin. Some infections induce hypo- or hyperpigmentation, which is associated with the activation of Toll-like receptors (TLRs), especially TLR4. Candida albicans is an opportunist pathogen that can switch between blastoconidia and hyphae forms; the latter is associated with invasion. Our objectives in this study were to ascertain whether C. albicans induces pigmentation in melanocytes and whether this process is dependent on TLR activation, as well as relating this with the antifungal activity of melanin as a first line of innate immunity against fungal infections. Normal human melanocytes were stimulated with C. albicans supernatants or with crude extracts of the blastoconidia or hyphae forms, and pigmentation and TLR2/TLR4 expression were measured. Expression of the melanosomal antigens Melan-A and gp100 was examined for any correlation with increased melanin levels or antifungal activity in melanocyte lysates. Melanosomal antigens were induced earlier than cell pigmentation, and hyphae induced stronger melanization than blastoconidia. Notably, when melanocytes were stimulated with crude extracts of C. albicans, the cell surface expression of TLR2/TLR4 began at 48 h post-stimulation and peaked at 72 h. At this time, blastoconidia induced both TLR2 and TLR4 expression, whereas hyphae only induced TLR4 expression. Taken together, these results suggest that melanocytes play a key role in innate immune responses against C. albicans infections by recognizing pathogenic forms of C. albicans via TLR4, resulting in increased melanin content and inhibition of infection.

  7. Engineering Melanin Nanoparticles as an Efficient Drug-Delivery System for Imaging-Guided Chemotherapy.

    PubMed

    Zhang, Ruiping; Fan, Quli; Yang, Min; Cheng, Kai; Lu, Xiaomei; Zhang, Lei; Huang, Wei; Cheng, Zhen

    2015-09-09

    In order to promote imaging-guided chemotherapy for preclinical and clinical applications, endogenous nanosystems with both contrast and drug-delivery properties are highly desired. Here, the simple use of melanin is first reported, and this biopolymer with good biocompatibility and biodegradability, binding ability to drugs and ions, and intrinsic photoacoustic properties, can serve as an efficient endogenous nanosystem for imaging-guided tumor chemotherapy in living mice.

  8. Two-photon excited fluorescence spectroscopy and imaging of melanin in vitro and in vivo

    NASA Astrophysics Data System (ADS)

    Krasieva, Tatiana B.; Liu, Feng; Sun, Chung-Ho; Kong, Yu; Balu, Mihaela; Meyskens, Frank L.; Tromberg, Bruce J.

    2012-03-01

    The ability to detect early melanoma non-invasively would improve clinical outcome and reduce mortality. Recent advances in two-photon excited fluorescence (TPEF) in vivo microscopy offer a powerful tool in early malignant melanoma diagnostics. The goal of this work was to develop a TPEF optical index for measuring relative concentrations of eumelanin and pheomelanin since ex vivo studies show that changes in this ratio have been associated with malignant transformation. We acquired TPEF emission spectra (λex=1000 nm) of melanin from several specimens, including human hair, malignant melanoma cell lines, and normal melanocytes and keratinocytes in different skin layers (epidermis, papillary dermis) in five healthy volunteers in vivo. We found that the pheomelanin emission peaks at around 620 nm and is blue-shifted from the eumelanin with broad maximum at 640-680nm. We defined "optical melanin index" (OMI) as a ratio of fluorescence signal intensities measured at 645 nm and 615nm. The measured OMI for a melanoma cell line MNT-1 was 1.6+/-0.2. The MNT-46 and MNT-62 lines (Mc1R gene knockdown) showed an anticipated change in melanins production ratio and had OMI of 0.55+/-0.05 and 0.17+/-0.02, respectively, which strongly correlated with HPLC data obtained for these lines. Average OMI measured for basal cells layers (melanocytes and keratinocytes) in normal human skin type I, II-III (not tanned and tanned) in vivo was 0.5, 1.05 and 1.16 respectively. We could not dependably detect the presence of pheomelanin in highly pigmented skin type V-VI. These data suggest that a non-invasive TPEF index could potentially be used for rapid melanin ratio characterization both in vitro and in vivo, including pigmented lesions.

  9. Conidial Dihydroxynaphthalene Melanin of the Human Pathogenic Fungus Aspergillus fumigatus Interferes with the Host Endocytosis Pathway.

    PubMed

    Thywißen, Andreas; Heinekamp, Thorsten; Dahse, Hans-Martin; Schmaler-Ripcke, Jeannette; Nietzsche, Sandor; Zipfel, Peter F; Brakhage, Axel A

    2011-01-01

    Aspergillus fumigatus is the most important air-borne fungal pathogen of humans. The interaction of the pathogen with the host's immune system represents a key process to understand pathogenicity. For elimination of invading microorganisms, they need to be efficiently phagocytosed and located in acidified phagolysosomes. However, as shown previously, A. fumigatus is able to manipulate the formation of functional phagolysosomes. Here, we demonstrate that in contrast to pigmentless pksP mutant conidia of A. fumigatus, the gray-green wild-type conidia inhibit the acidification of phagolysosomes of alveolar macrophages, monocyte-derived macrophages, and human neutrophil granulocytes. Therefore, this inhibition is independent of the cell type and applies to the major immune effector cells required for defense against A. fumigatus. Studies with melanin ghosts indicate that the inhibitory effect of wild-type conidia is due to their dihydroxynaphthalene (DHN)-melanin covering the conidia, whereas the hydrophobin RodA rodlet layer plays no role in this process. This is also supported by the observation that pksP conidia still exhibit the RodA hydrophobin layer, as shown by scanning electron microscopy. Mutants defective in different steps of the DHN-melanin biosynthesis showed stronger inhibition than pksP mutant conidia but lower inhibition than wild-type conidia. Moreover, A. fumigatus and A. flavus led to a stronger inhibition of phagolysosomal acidification than A. nidulans and A. terreus. These data indicate that a certain type of DHN-melanin that is different in the various Aspergillus species, is required for maximal inhibition of phagolysosomal acidification. Finally, we identified the vacuolar ATPase (vATPase) as potential target for A. fumigatus based on the finding that addition of bafilomycin which inhibits vATPase, led to complete inhibition of the acidification whereas the fusion of phagosomes containing wild-type conidia and lysosomes was not affected.

  10. Conidial Dihydroxynaphthalene Melanin of the Human Pathogenic Fungus Aspergillus fumigatus Interferes with the Host Endocytosis Pathway

    PubMed Central

    Thywißen, Andreas; Heinekamp, Thorsten; Dahse, Hans-Martin; Schmaler-Ripcke, Jeannette; Nietzsche, Sandor; Zipfel, Peter F.; Brakhage, Axel A.

    2011-01-01

    Aspergillus fumigatus is the most important air-borne fungal pathogen of humans. The interaction of the pathogen with the host's immune system represents a key process to understand pathogenicity. For elimination of invading microorganisms, they need to be efficiently phagocytosed and located in acidified phagolysosomes. However, as shown previously, A. fumigatus is able to manipulate the formation of functional phagolysosomes. Here, we demonstrate that in contrast to pigmentless pksP mutant conidia of A. fumigatus, the gray-green wild-type conidia inhibit the acidification of phagolysosomes of alveolar macrophages, monocyte-derived macrophages, and human neutrophil granulocytes. Therefore, this inhibition is independent of the cell type and applies to the major immune effector cells required for defense against A. fumigatus. Studies with melanin ghosts indicate that the inhibitory effect of wild-type conidia is due to their dihydroxynaphthalene (DHN)-melanin covering the conidia, whereas the hydrophobin RodA rodlet layer plays no role in this process. This is also supported by the observation that pksP conidia still exhibit the RodA hydrophobin layer, as shown by scanning electron microscopy. Mutants defective in different steps of the DHN-melanin biosynthesis showed stronger inhibition than pksP mutant conidia but lower inhibition than wild-type conidia. Moreover, A. fumigatus and A. flavus led to a stronger inhibition of phagolysosomal acidification than A. nidulans and A. terreus. These data indicate that a certain type of DHN-melanin that is different in the various Aspergillus species, is required for maximal inhibition of phagolysosomal acidification. Finally, we identified the vacuolar ATPase (vATPase) as potential target for A. fumigatus based on the finding that addition of bafilomycin which inhibits vATPase, led to complete inhibition of the acidification whereas the fusion of phagosomes containing wild-type conidia and lysosomes was not affected. PMID

  11. A band model for melanin deducted from optical absorption and photoconductivity experiments.

    PubMed

    Crippa, P R; Cristofoletti, V; Romeo, N

    1978-01-03

    Natural and synthetic melanins have been studied by optical absorption and photoconductivity measurements in the range 200--700 nm. Both optical absorption and photoconductivity increase in the ultraviolet region, and a negative photoconductivity was observed with a maximum near 500 nm. This behaviour has been interpreted by the band model of amorphous materials and an "optical gap" of 3.4 eV has been determined.

  12. Isolation, fractionation and characterization of melanin-like pigments from chestnut (Castanea mollissima) shells.

    PubMed

    Yao, Zengyu; Qi, Jianhua; Wang, Lihua

    2012-06-01

    Melanins are known as versatile biopolymers, but the utilizations are restricted by their poor solubilities. Therefore, well soluble ones or their analogs are much desired. In this article, a new procedure was developed for fractionation of the pigments isolated from chestnut (Castanea mollissima) shells, and 3 fractions (Fr. 1, Fr. 2, and Fr. 3) were obtained. The solubilities of all the fractions in waters of different pH and in common organic solvents were studied. The physicochemical properties of the fractions were characterized for the first time on the basis of combined chemical analyses and spectroscopic methods including ultraviolet-visible (UV-Vis), Fourier transform infrared (FT-IR), electron spin resonance (ESR), and solid-state ¹³C nuclear magnetic resonance (¹³C-NMR). All the fractions could be bleached by NaOCl and H₂O₂ and give a positive reaction for polyphenols, which are usually used as typical tests for allomelanins. Their UV-Vis, FT-IR, and ESR spectra resembled those of synthetic and some natural melanins. Elemental data and quantitative analyses of ¹³C-NMR spectra revealed that pigment-bound proteins and polysaccharides were the most abundant in Fr. 1, while Fr. 2 was presented with the highest aromaticity. We provided a new, simple, and inexpensive method to fractionate the melanin-like pigments from chestnut shells. This technique can be used to produce natural melanin-like food colorants with different solubilities from chestnut shells. © 2012 Institute of Food Technologists®

  13. Evidence of selection at melanin synthesis pathway loci during silkworm domestication.

    PubMed

    Yu, Hong-Song; Shen, Yi-Hong; Yuan, Gang-Xiang; Hu, Yong-Gang; Xu, Hong-En; Xiang, Zhong-Huai; Zhang, Ze

    2011-06-01

    The domesticated silkworm (Bombyx mori) was domesticated from wild silkworm (Bombyx mandarina) more than 5,000 years ago. During domestication, body color between B. mandarina and B. mori changed dramatically. However, the molecular mechanism of the silkworm body color transition is not known. In the present study, we examined within- and between-species nucleotide diversity for eight silkworm melanin synthesis pathway genes, which play a key role in cuticular pigmentation of insects. Our results showed that the genetic diversity of B. mori was significantly lower than that of B. mandarina and 40.7% of the genetic diversity of wild silkworm was lost in domesticated silkworm. We also examined whether position effect exists among melanin synthesis pathway genes in B. mandarina and B. mori. We found that the upstream genes have significantly lower levels of genetic diversity than the downstream genes, supporting a functional constraint hypothesis (FCH) of metabolic pathway, that is, upstream enzymes are under greater selective constraint than downstream enzymes because upstream enzymes participate in biosynthesis of a number of metabolites. We also investigated whether some of the melanin synthesis pathway genes experienced selection during domestication. Neutrality test, coalescent simulation, as well as network and phylogenetic analyses showed that tyrosine hydroxylase (TH) gene was a domestication locus. Sequence analysis further suggested that a putative expression enhancer (Abd-B-binding site) in the intron of TH gene might be disrupted during domestication. TH is the rate-limiting enzyme of melanin synthesis pathway in insects. Real-time polymerase chain reaction assay did show that the relative expression levels of TH gene in B. mori were significantly lower than that in B. mandarina at three different developmental stages, which is consistent with light body color of domesticated silkworm relative to wild silkworm. Therefore, we speculated that expression

  14. Melanin Protects Paracoccidioides brasiliensis from the Effects of Antimicrobial Photodynamic Inhibition and Antifungal Drugs

    PubMed Central

    Baltazar, Ludmila Matos; Werneck, Silvia Maria Cordeiro; Soares, Betânia Maria; Ferreira, Marcus Vinicius L.; Souza, Danielle G.; Pinotti, Marcos; Santos, Daniel Assis

    2015-01-01

    Paracoccidioidomycosis (PCM) is a public health concern in Latin America and South America that when not correctly treated can lead to patient death. In this study, the influence of melanin produced by Paracoccidioides spp. on the effects of treatment with antimicrobial photodynamic inhibition (aPI) and antifungal drugs was evaluated. aPI was performed using toluidine blue (TBO) as a photosensitizer and a 630-nm light-emitting diode (LED) light. The antifungals tested were itraconazole and amphotericin B. We evaluated the effects of each approach, aPI or antifungals, against nonmelanized and melanized yeast cells by performing susceptibility tests and by quantifying oxidative and nitrosative bursts during the experiments. aPI reduced nonmelanized cells by 3.0 log units and melanized cells by 1.3 log units. The results showed that melanization protects the fungal cell, probably by acting as a scavenger of nitric oxide and reactive oxygen species, but not of peroxynitrite. Melanin also increased the MICs of itraconazole and amphotericin B, and the drugs were fungicidal for nonmelanized and fungistatic for melanized yeast cells. Our study shows that melanin production by Paracoccidioides yeast cells serves a protective function during aPI and treatment with itraconazole and amphotericin B. The results suggest that melanin binds to the drugs, changing their antifungal activities, and also acts as a scavenger of reactive oxygen species and nitric oxide, but not of peroxynitrite, indicating that peroxynitrite is the main radical that is responsible for fungal death after aPI. PMID:25896704

  15. Biocatalysis on the surface of Escherichia coli: melanin pigmentation of the cell exterior

    PubMed Central

    Gustavsson, Martin; Hörnström, David; Lundh, Susanna; Belotserkovsky, Jaroslav; Larsson, Gen

    2016-01-01

    Today, it is considered state-of-the-art to engineer living organisms for various biotechnology applications. Even though this has led to numerous scientific breakthroughs, the enclosed interior of bacterial cells still restricts interactions with enzymes, pathways and products due to the mass-transfer barrier formed by the cell envelope. To promote accessibility, we propose engineering of biocatalytic reactions and subsequent product deposition directly on the bacterial surface. As a proof-of-concept, we used the AIDA autotransporter vehicle for Escherichia coli surface expression of tyrosinase and fully oxidized externally added tyrosine to the biopolymer melanin. This resulted in a color change and creation of a black cell exterior. The capture of ninety percent of a pharmaceutical wastewater pollutant followed by regeneration of the cell bound melanin matrix through a simple pH change, shows the superior function and facilitated processing provided by the surface methodology. The broad adsorption spectrum of melanin could also allow removal of other micropollutants. PMID:27782179

  16. Prenylated flavonoids from Artocarpus altilis: antioxidant activities and inhibitory effects on melanin production.

    PubMed

    Lan, Wen-Chun; Tzeng, Cheng-Wei; Lin, Chun-Ching; Yen, Feng-Lin; Ko, Horng-Huey

    2013-05-01

    Flavonoids, 10-oxoartogomezianone (1), 8-geranyl-3-(hydroxyprenyl)isoetin (2), hydroxyartoflavone A (3), isocycloartobiloxanthone (4), and furanocyclocommunin (5), together with 12 known compounds, were isolated from heartwood and cortex of Artocarpus altilis, and their structures were identified by comparing their spectra with those of similar compounds. To identify natural antioxidants and whitening agents, the ability of these prenylated flavonoids was assessed to scavenge the 1,1-diphenyl-2-picrylhydrazyl radical (DPPH), the 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS(+·)) radical cation, and the superoxide anion (O2(-·)), and their abilities to inhibit tyrosinase and melanin production. It was found that compounds 3, 4, and artoflavone A (15) had moderate DPPH(·)-scavenging activity, whereas compound 4 exhibited significant ABTS(+·)-scavenging activity, and that norartocarpetin (7) and artogomezianone (8) exhibited moderate ABTS(+·)-scavenging activity, with compounds 2, 7, and artocarpin (6) displaying good superoxide anion-scavenging activity. In addition, compounds 7, 8, cudraflavone A (14), and artonin M (17), inhibited melanin production by strongly suppressing tyrosinase activity. Compound 6 reduced the melanin content without inhibiting tyrosinase activity. These results suggest that flavonoids isolated from A. altilis may be candidate antioxidants and/or skin-whitening agents. However, further investigations are required to determine their mechanisms of action. Copyright © 2013 Elsevier Ltd. All rights reserved.

  17. Ultrasonic shear spectrum in hydrated diethylamine melanins and its relation to stacking in a planar group

    NASA Astrophysics Data System (ADS)

    Kono, Ryusuke; Yoshizaki, Haruyo; Miyake, Yasuhiro; Izumi, Yoshinobu; McGinness, John E.

    1981-11-01

    Shear mechanical relaxation and resonance data are reported for 20 wt % hydration of diethylamine melanins with different pH values ranging from 2 to 7. Shear impedance measurements in the temperature range from 60 to -80 °C, with frequencies from 1 to 362 MHz, indicate a Davidson-Cole spectrum in the primary relaxation and a single relaxation with a characteristic frequency of f = 4 MHz at 60 °C referred to the molecular motions of a group composed of an average molecular weight Mn?1.4×104. A resonance at 250 MHz is found in the specific melanin called No. 1, associated with stacking of indole monomer units, and a single relaxation at f = 270 MHz at 60 °C is found in the hydrate of melanin No. 2. The nature of the stacking is surveyed on account of Fitzgerald's theory. The limiting shear modulus in the primary relaxation related to the molecular motion of backbone chains obeys the modified Hirai-Eyring equation. All the hydrations have an amorphous phase composed of a three-dimensional network structure.

  18. Melanin granule model for laser-induced thermal damage in the retina

    SciTech Connect

    Thompson, C.R.; Rogers, M.E.; Gerstman, B.S.; Jacques, S.L.

    1996-05-01

    An analytical model for thermal damage of retinal tissue due to absorption of laser energy by finite-sized melanin granules is developed. Since melanin is the primary absorber of visible and near-IR light in the skin and in the retina, bulk heating of tissue can be determined by superposition of individual melanin granule effects. Granules are modeled as absorbing spheres surrounded by an infinite medium of water. Analytical solutions to the heat equation result in computations that are quick and accurate. Moreover, the model does not rely on symmetric beam profiles, and so arbitrary images can be studied. The important contribution of this model is to provide a more accurate biological description of submillisecond pulse exposures than previous retinal models, while achieving agreement for longer pulses. This model can also be naturally extended into the sub-microsecond domain by including vaporization as a damage mechanism. It therefore represents the beginning of a model which can be applied across the entire pulse duration domain.

  19. Specific melanin content in human hairs and mitochondrial DNA typing success.

    PubMed

    Linch, Charles A; Champagne, Jarrod R; Bonnette, Michelle D; Dawson Cruz, Tracey

    2009-06-01

    This study investigated whether a difference exists in the ability to obtain quality mitochondrial DNA (mtDNA) sequence data from hair shafts due to specific melanin content differences. Eumelanin, the pigment in darker hairs, protects nuclear DNA in the skin by absorbing and scattering UV radiation. In contrast, sensitized pheomelanin, the predominate melanin in red hairs and some blond hairs, is unable to prevent DNA damage in skin upon exposure to UV radiation. It has been reported in the literature that darker hairs (predominate eumelanin content) have a higher mtDNA sequencing success rate than lighter colored hairs. However, others have reported to the contrary when different methodologies are used. In this study, 2-cm hair fragments were cut from dark brown, red, and gray white hairs and typed using standard casework mtDNA sequence analysis methods. All 30 hair fragments produced quality mtDNA sequence data on first attempt from the second half of hypervariable region 1. These results are likely due to the apparent shielding of mtDNA by the hard protein of the hair shaft fiber from radiation-induced damage, regardless of melanin type, after 10-months minimal solar exposure. Nonetheless, this study may serve as a guide for future quantitative studies that investigate hair mtDNA photodamage in circumstances of increased solar, chemical, environmental, or mechanical damage.

  20. Three-photon fluorescence imaging of melanin with a dual-wedge confocal scanning system

    NASA Astrophysics Data System (ADS)

    Mega, Yair; Kerimo, Joseph; Robinson, Joseph; Vakili, Ali; Johnson, Nicolette; DiMarzio, Charles

    2012-03-01

    Confocal microscopy can be used as a practical tool in non-invasive applications in medical diagnostics and evaluation. In particular, it is being used for the early detection of skin cancer to identify pathological cellular components and, potentially, replace conventional biopsies. The detection of melanin and its spatial location and distribution plays a crucial role in the detection and evaluation of skin cancer. Our previous work has shown that the visible emission from melanin is strong and can be easily observed with a near-infrared CW laser using low power. This is due to a unique step-wise, (SW) three-photon excitation of melanin. This paper shows that the same SW, 3-photon fluorescence can also be achieved with an inexpensive, continuous-wave laser using a dual-prism scanning system. This demonstrates that the technology could be integrated into a portable confocal microscope for clinical applications. The results presented here are in agreement with images obtained with the larger and more expensive femtosecond laser system used earlier.

  1. Inhibitory effects of different fractions of Nepeta satureioides on melanin synthesis through reducing oxidative stress.

    PubMed

    Emami, Seyed Ahmad; Yazdian-Robati, Rezvan; Sadeghi, Mohammad; Baharara, Javad; Amini, Elaheh; Salek, Farzaneh; Tayarani-Najaran, Zahra

    2017-04-01

    Nepeta satureioides Boiss. has been used in traditional medicine of eastern countries and is famous for its medicinal properties. The aim of this study was to evaluate the effect of methanol (MeOH), n-hexane and dichloromethane (CH2Cl2) fractions of the extract on melanin synthesis and oxidative stress in B16F10 melanoma cell line. The B16F10 cell line viability after treatment with increasing concentrations of different fractions of the plant (5-60 μg/mL) was measured using MTT assay. The inhibitory effect on synthesis of melanin, mushroom tyrosinase activity, cellular tyrosinase and oxidative stress were determined by the colorimetric and fluorometric methods. The data showed that at concentrations below 60 μg/mL, fractions did not show significant toxicity on melanoma cells. The amount of melanin synthesis by MeOH and CH2Cl2 fractions and mushroom tyrosinase activity by the MeOH fraction declined in B16F10 cells. In addition to the capacity of MeOH, n-hexane and CH2Cl2 fractions in decreasing the amount of reactive oxygen species (ROS) in melanoma cells, all fractions revealed remarkable antioxidant activity. The melanogenesis inhibitory and antioxidant effects of N. satureioides on B16F10 cells may suggest this plant as a new pharmaceutical agent in reducing skin pigment and skin aging in cosmetic industry.

  2. Inhibitory effects of different fractions of Nepeta satureioides on melanin synthesis through reducing oxidative stress

    PubMed Central

    Emami, Seyed Ahmad; Yazdian-Robati, Rezvan; Sadeghi, Mohammad; Baharara, Javad; Amini, Elaheh; Salek, Farzaneh; Tayarani-Najaran, Zahra

    2017-01-01

    Nepeta satureioides Boiss. has been used in traditional medicine of eastern countries and is famous for its medicinal properties. The aim of this study was to evaluate the effect of methanol (MeOH), n-hexane and dichloromethane (CH2Cl2) fractions of the extract on melanin synthesis and oxidative stress in B16F10 melanoma cell line. The B16F10 cell line viability after treatment with increasing concentrations of different fractions of the plant (5-60 μg/mL) was measured using MTT assay. The inhibitory effect on synthesis of melanin, mushroom tyrosinase activity, cellular tyrosinase and oxidative stress were determined by the colorimetric and fluorometric methods. The data showed that at concentrations below 60 μg/mL, fractions did not show significant toxicity on melanoma cells. The amount of melanin synthesis by MeOH and CH2Cl2 fractions and mushroom tyrosinase activity by the MeOH fraction declined in B16F10 cells. In addition to the capacity of MeOH, n-hexane and CH2Cl2 fractions in decreasing the amount of reactive oxygen species (ROS) in melanoma cells, all fractions revealed remarkable antioxidant activity. The melanogenesis inhibitory and antioxidant effects of N. satureioides on B16F10 cells may suggest this plant as a new pharmaceutical agent in reducing skin pigment and skin aging in cosmetic industry. PMID:28515769

  3. Multi-spectral mapping of in vivo skin hemoglobin and melanin

    NASA Astrophysics Data System (ADS)

    Jakovels, Dainis; Spigulis, Janis; Saknite, Inga

    2010-04-01

    The multi-spectral imaging technique has been used for distant mapping of in-vivo skin chromophores by analyzing spectral data at each reflected image pixel and constructing 2-D maps of the relative concentrations of oxy-/deoxyhemoglobin and melanin. Instead of using a broad visible-NIR spectral range, this study focuses on narrowed spectral band 500-700 nm, so speeding-up the signal processing procedure. Regression analysis confirmed that superposition of three Gaussians is optimal analytic approximation for the oxy-hemoglobin absorption tabular spectrum in this spectral band, while superposition of two Gaussians fits well for deoxy-hemoglobin absorption and exponential function - for melanin absorption. The proposed approach was clinically tested for three types of in-vivo skin provocations - ultraviolet irradiance, chemical reaction with vinegar essence and finger arterial occlusion. Spectral range 500-700 nm provided better sensitivity to oxy-hemoglobin changes and higher response stability to melanin than two reduced ranges 500-600 nm and 530-620 nm.

  4. [Melanin properties studies of the recombinant of Pseudomonas pseudoalcaligenes containing tyrosinase gene].

    PubMed

    Cai, X

    2001-12-01

    Pseudomonas pseudoalcaligenes is a notably killing maggots bacterium, which was isolated from natural dead maggots. Tyrosinase gene of P. maltophilia AT18 has been introduced into P. pseudoalcaligenes, and enabled it the ability of producing melanin steadily. Antiradiation effect of the melanin is quite strong. The melanin of the recombinant is nonfixiform material. It's solubility is very little in many sorts of organic or inorganic solvent. It's solubility is big in alkaline solution, but little in neutral or weak acid solution. It is deposited when pH < 4. It is oxidized by H2O2 or NaC10. It is also reduced by Ag+ or H2S. It has free radical and it can absorbs free radical generated by ultra-violent ray. It can absorbs ray of all sorts of wave length. The absorption rate of ultra-violet ray is the biggest in all sorts of wave length. It can effectively protects protein, DNA and other biomacromolecule matter against the damages by ultra-violet ray.

  5. Melanin granula distribution and phagocytosis in psoriasis vulgaris after PUVA therapy.

    PubMed

    Stüttgen, G; Brinkmann-Raestrupp, I; Haller, L; Kentsch, V; Schalla, W

    1979-02-23

    Melanin-containing basal cells of the epidermis, melanin-containing macrophages, mast cells, eosinophilic granulocytes and plasma cells were quantitatively investigated with the purpose of gaining an understanding of the quantitative changes in these cell systems under PUVA therapy. This patients have been exposed to solar radiation some weeks or months before the begin of the PUVA-treatment. Different dying-processes were used to investigate biopsy samples of psoriatically healthy and psoriatically affected skin, from 28 patients before, and 39 patients after PUVA therapy, using a 2 d micrometer with a field of view of 0.1 mm2. Altogether more than 9,000 fields of view have been analysed. The average radiation amount was 12 irradiations with an average total energy of 21.5 J/cm2. It was found that the count of granula-containing basal layer cells decreases in the psoriatic "healthy" region due to pigment incontinence and increase in the psoriatically affected region. The subepidermal melanin-containing phagocytes increase in both regions to a similar extent. In the case of the mast cells there was no trend to degranulation. The count of eosinophilic granulocytes and plasma cells was unchanged.

  6. Synthesis and in Vivo Evaluation of [123I]Melanin-Targeted Agents.

    PubMed

    Roberts, Maxine P; Nguyen, Vu; Ashford, Mark E; Berghofer, Paula; Wyatt, Naomi A; Krause-Heuer, Anwen M; Pham, Tien Q; Taylor, Stephen R; Hogan, Leena; Jiang, Cathy D; Fraser, Benjamin H; Lengkeek, Nigel A; Matesic, Lidia; Gregoire, Marie-Claude; Denoyer, Delphine; Hicks, Rodney J; Katsifis, Andrew; Greguric, Ivan

    2015-08-13

    This study reports the synthesis, [(123)I]radiolabeling, and biological profile of a new series of iodinated compounds for potential translation to the corresponding [(131)I]radiolabeled compounds for radionuclide therapy of melanoma. Radiolabeling was achieved via standard electrophilic iododestannylation in 60-90% radiochemical yield. Preliminary SPECT imaging demonstrated high and distinct tumor uptake of all compounds, as well as high tumor-to-background ratios compared to the literature compound [(123)I]4 (ICF01012). The most favorable compounds ([(123)I]20, [(123)I]23, [(123)I]41, and [(123)I]53) were selected for further biological investigation. Biodistribution studies indicated that all four compounds bound to melanin containing tissue with low in vivo deiodination; [(123)I]20 and [(123)I]53 in particular displayed high and prolonged tumor uptake (13% ID/g at 48 h). [(123)I]53 had the most favorable overall profile of the cumulative uptake over time of radiosensitive organs. Metabolite analysis of the four radiotracers found [(123)I]41 and [(123)I]53 to be the most favorable, displaying high and prolonged amounts of intact tracer in melanin containing tissues, suggesting melanin specific binding. Results herein suggest that compound [(123)I]53 displays favorable in vivo pharmacokinetics and stability and hence is an ideal candidate to proceed with further preclinical [(131)I] therapeutic evaluation.

  7. Physicochemical characteristics and antioxidant activity of arginine-modified melanin from Lachnum YM-346.

    PubMed

    Ye, Ming; Wang, Yan; Guo, Geng-yi; He, Yun-long; Lu, Ying; Ye, Ying-wang; Yang, Qing-hua; Yang, Pei-zhou

    2012-12-15

    Seven kinds of amino acids were used to modify the non-water-soluble extracellular melanin (LEM346) from Lachnum YM-346. It was found that arginine-melanin (ALEM346) had the highest solubility, being 4.55% (gg(-1)) in 30°C distilled water. Elemental analysis, infrared spectrum and mass spectrum analysis revealed that LEM346 molecule contained indole quinone structure, its molecular formula speculated to be C(18)H(8)O(6)N(2). Infrared spectrum analysis showed that ALEM346 had characteristic absorption peaks at 1672.346 and 1637.679 cm(-1). Mass spectrum analysis indicated that ALEM346 contained three types of arginine-melanin molecules. When the ALEM346 concentration was 500 mgL(-1), its total antioxidant capacity was equivalent to α-tocopherol of 46.65 mmolL(-1), the DPPH() and O(2)(-) scavenging rates and the Fe(2+) chelating rate were 89.05%, 93.81% and 80.18%, respectively, suggesting that the antioxidant activity of ALEM346 was stronger than that of LEM346.

  8. Effect of oxygen on free radicals in DOPA-melanin complexes with netilmicin, diamagnetic Zn(II), and paramagnetic Cu(II)

    NASA Astrophysics Data System (ADS)

    Zdybel, Magdalena; Pilawa, Barbara; Buszman, Ewa; Wrześniok, Dorota

    2013-01-01

    Electron paramagnetic resonance (EPR) spectroscopy was used to examine interactions between molecules of oxygen O2 and free radicals of DOPA-melanin and its complexes with netilmicin, Zn(II) and Cu(II). EPR spectra were measured for evacuated samples and then compared to earlier data for the samples in air. The concentrations of free radicals in the evacuated samples were higher than for samples in air. The strongest effect was observed for DOPA-melanin and melanin samples containing Cu(II). Evacuation of DOPA-melanin and DOPA-melanin-Cu(II) samples causes high EPR line broadening. Faster spin-lattice relaxation processes exist in evacuated melanin samples than in samples in air.

  9. Immunity to melanin and to tyrosinase in melanoma patients, and in people with vitiligo.

    PubMed

    Dorđić, Marija; Matić, Ivana Z; Filipović-Lješković, Ivana; Džodić, Radan; Sašić, Miomir; Erić-Nikolić, Aleksandra; Vuletić, Ana; Kolundžija, Branka; Damjanović, Ana; Grozdanić, Nađa; Nikolić, Srđan; Pralica, Janko; Dobrosavljević, Danijela; Rašković, Sanvila; Andrejević, Slađana; Juranić, Zorica

    2012-07-26

    The aim of this study was to determine the presence and the intensity of humoral immunity to melanoma-associated antigens: tyrosinase and melanin, in patients with melanoma, in persons with vitiligo and in control healthy people. The study involved 63 patients with melanoma and 19 persons with vitiligo. Control group consisted up to 41 healthy volunteers. Mushroom tyrosinase and synthetic melanin were used as the antigens. ELISA test showed significantly (p < 0.0000004 and p < 0.04) lower levels of IgM anti-tyrosinase autoantibodies, in melanoma and vitiligo patients respectively, compared to controls.Although there was no significant difference between the levels of IgA anti-melanin autoantibodies in melanoma or vitiligo patients in comparison with controls, the enhanced concentrations of anti-melanin IgA autoantibodies were preferentially found in melanoma patients with metastatic disease. Significantly high percentage in the Fc alphaRI (CD89) positive cells was determined in melanoma patients (p < 0.002 and p < 0.008) in comparison to that found in healthy people or in patients with vitiligo, in the already mentioned order, pointing that IgA dependent cellular cytotoxicity is not important for the immune action against melanoma, even more that it is included in some immune suppression.Levels of IgG autoantibodies to mentioned antigens in melanoma patients although low were not significantly lower from controls. These findings analyzed together with the statistically significant low percentage of FcgammaRIII, (CD16) positive immunocompetent cells (p < 0.0007 and p < 0.003), which was found in patients with melanoma compared with healthy or vitiligo people respectively, and statistically significant low percentage of (CD16 + CD56+) natural killer (NK) cells (p < 0.005) found in melanoma patients in comparison to healthy controls pointed to the low probability for anti-melanoma IgG mediated, antibody mediated cellular cytotoxicity

  10. Mechanical and photo-fragmentation processes for nanonization of melanin to improve its efficacy in protecting cells from reactive oxygen species stress

    NASA Astrophysics Data System (ADS)

    Liu, Yi-Cheng; Chen, Sih-Min; Liu, Jhong-Han; Hsu, Hsiang-Wei; Lin, Hoang-Yan; Chen, Szu-yuan

    2015-02-01

    It has been well established ex vivo that melanin has the ability of scavenging free radicals and reactive oxygen species (ROS), besides other functions. Therefore, we propose to utilize nanonized melanin as medication against acute oxidative stress. For this purpose, we developed and characterized two techniques based on mechanical stir and photo-fragmentation using femtosecond laser pulses, respectively, for disintegration of suspended melanin powder to produce nanometer-sized and water-dispersible melanin. This resolves a major obstacle in the medical and industrial applications of melanin. The viabilities of cultured retinal pigment epithelium (RPE) cells exposed to exogenous H2O2 stress and treated with various conditions of melanin and irradiation were compared. It was found that melanin could be nanonized very effectively with the techniques, and nanonized melanin exhibited a much stronger effect than unprocessed melanin on raising the viability of cultured RPE cells under acute ROS stress. The effect was even more prominent without simultaneous light irradiation, promising for effective in vivo application to the whole body.

  11. Mechanical and photo-fragmentation processes for nanonization of melanin to improve its efficacy in protecting cells from reactive oxygen species stress

    SciTech Connect

    Liu, Yi-Cheng; Chen, Sih-Min; Liu, Jhong-Han; Hsu, Hsiang-Wei; Lin, Hoang-Yan; Chen, Szu-yuan

    2015-02-14

    It has been well established ex vivo that melanin has the ability of scavenging free radicals and reactive oxygen species (ROS), besides other functions. Therefore, we propose to utilize nanonized melanin as medication against acute oxidative stress. For this purpose, we developed and characterized two techniques based on mechanical stir and photo-fragmentation using femtosecond laser pulses, respectively, for disintegration of suspended melanin powder to produce nanometer-sized and water-dispersible melanin. This resolves a major obstacle in the medical and industrial applications of melanin. The viabilities of cultured retinal pigment epithelium (RPE) cells exposed to exogenous H{sub 2}O{sub 2} stress and treated with various conditions of melanin and irradiation were compared. It was found that melanin could be nanonized very effectively with the techniques, and nanonized melanin exhibited a much stronger effect than unprocessed melanin on raising the viability of cultured RPE cells under acute ROS stress. The effect was even more prominent without simultaneous light irradiation, promising for effective in vivo application to the whole body.

  12. 3, 4-dihydroxy-L-phenylalanine-derived melanin from Yarrowia lipolytica mediates the synthesis of silver and gold nanostructures

    PubMed Central

    2013-01-01

    Background Nanobiotechnology applies the capabilities of biological systems in generating a variety of nano-sized structures. Plants, algae, fungi and bacteria are some systems mediating such reactions. In fungi, the synthesis of melanin is an important strategy for cell-survival under metal-stressed conditions. Yarrowia lipolytica, the biotechnologically significant yeast also produces melanin that sequesters heavy metal ions. The content of this cell-associated melanin is often low and precursors such as L-tyrosine or 3, 4-dihydroxy-L-phenylalanine (L-DOPA) can enhance its production. The induced melanin has not been exploited for the synthesis of nanostructures. In this investigation, we have employed L-DOPA-melanin for the facile synthesis of silver and gold nanostructures. The former have been used for the development of anti-fungal paints. Methods Yarrowia lipolytica NCIM 3590 cells were incubated with L-DOPA for 18 h and the resultant dark pigment was subjected to physical and chemical analysis. This biopolymer was used as a reducing and stabilizing agent for the synthesis of silver and gold nanostructures. These nanoparticles were characterized by UV-Visible spectra, X-ray diffraction (XRD) studies, and electron microscopy. Silver nanoparticles were evaluated for anti-fungal activity. Results The pigment isolated from Y. lipolytica was identified as melanin. The induced pigment reduced silver nitrate and chloroauric acid to silver and gold nanostructures, respectively. The silver nanoparticles were smaller in size (7 nm) and displayed excellent anti-fungal properties towards an Aspergillus sp. isolated from a wall surface. An application of these nanoparticles as effective paint-additives has been demonstrated. Conclusion The yeast mediated enhanced production of the metal-ion-reducing pigment, melanin. A simple and rapid method for the extracellular synthesis of nanoparticles with paint-additive-application was developed. PMID:23363424

  13. 3, 4-dihydroxy-L-phenylalanine-derived melanin from Yarrowia lipolytica mediates the synthesis of silver and gold nanostructures.

    PubMed

    Apte, Mugdha; Girme, Gauri; Bankar, Ashok; Ravikumar, Ameeta; Zinjarde, Smita

    2013-01-30

    Nanobiotechnology applies the capabilities of biological systems in generating a variety of nano-sized structures. Plants, algae, fungi and bacteria are some systems mediating such reactions. In fungi, the synthesis of melanin is an important strategy for cell-survival under metal-stressed conditions. Yarrowia lipolytica, the biotechnologically significant yeast also produces melanin that sequesters heavy metal ions. The content of this cell-associated melanin is often low and precursors such as L-tyrosine or 3, 4-dihydroxy-L-phenylalanine (L-DOPA) can enhance its production. The induced melanin has not been exploited for the synthesis of nanostructures. In this investigation, we have employed L-DOPA-melanin for the facile synthesis of silver and gold nanostructures. The former have been used for the development of anti-fungal paints. Yarrowia lipolytica NCIM 3590 cells were incubated with L-DOPA for 18 h and the resultant dark pigment was subjected to physical and chemical analysis. This biopolymer was used as a reducing and stabilizing agent for the synthesis of silver and gold nanostructures. These nanoparticles were characterized by UV-Visible spectra, X-ray diffraction (XRD) studies, and electron microscopy. Silver nanoparticles were evaluated for anti-fungal activity. The pigment isolated from Y. lipolytica was identified as melanin. The induced pigment reduced silver nitrate and chloroauric acid to silver and gold nanostructures, respectively. The silver nanoparticles were smaller in size (7 nm) and displayed excellent anti-fungal properties towards an Aspergillus sp. isolated from a wall surface. An application of these nanoparticles as effective paint-additives has been demonstrated. The yeast mediated enhanced production of the metal-ion-reducing pigment, melanin. A simple and rapid method for the extracellular synthesis of nanoparticles with paint-additive-application was developed.

  14. Effect of biotransformation by liver S9 enzymes on the mutagenicity and cytotoxicity of melanin extracted from Aspergillus nidulans.

    PubMed

    de Cássia Ribeiro Gonçalves, Rita; Rezende Kitagawa, Rodrigo; Aparecida Varanda, Eliana; Stella Gonçalves Raddi, Maria; Andrea Leite, Carla; Regina Pombeiro Sponchiado, Sandra

    2016-01-01

    A mutant that exhibited increased melanin pigment production was isolated from Aspergillus nidulans fungus. This pigment has aroused biotechnological interest due to its photoprotector and antioxidant properties. In a recent study, we showed that melanin from A. nidulans also inhibits NO and TNF-α production. The present study evaluates the mutagenicity and cytotoxicity of melanin extracted from A. nidulans after its exposure to liver S9 enzymes. The cytotoxicity of multiple concentrations of melanin (31.2-500 μg/mL) against the McCoy cell line was evaluated using the Neutral Red assay, after incubation for 24 h. Mutagenicity was assessed using the Ames test with the Salmonella typhimurium strains TA98, TA97a, TA100, and TA102 at concentrations ranging from 125 μg/plate to 1 mg/plate after incubation for 48 h. The cytotoxicity of A. nidulans melanin after incubation with S9 enzymes was less than (CI50 value= 413.4 ± 3.1 μg/mL) that of other toxins, such as cyclophosphamide (CI50 value = 15 ± 1.2 μg/mL), suggesting that even the metabolised pigment does not cause significant damage to cellular components at concentrations up to 100 μg/mL. In addition, melanin did not exhibit mutagenic properties against the TA 97a, TA 98, TA 100, or TA 102 strains of S. typhimurium, as shown by a mutagenic index (MI)  <2 in all assays. The significance of these results supports the use of melanin as a therapeutic reagent because it possesses low cytotoxicity and mutagenic potential, even when processed through an external metabolising system.

  15. The pbrB gene encodes a laccase required for DHN-melanin synthesis in conidia of Talaromyces (Penicillium) marneffei.

    PubMed

    Sapmak, Ariya; Boyce, Kylie J; Andrianopoulos, Alex; Vanittanakom, Nongnuch

    2015-01-01

    Talaromyces marneffei (Basionym: Penicillium marneffei) is a significant opportunistic fungal pathogen in patients infected with human immunodeficiency virus in Southeast Asia. T. marneffei cells have been shown to become melanized in vivo. Melanins are pigment biopolymers which act as a non-specific protectant against various stressors and which play an important role during virulence in fungi. The synthesis of the two most commonly found melanins in fungi, the eumelanin DOPA-melanin and the allomelanin DHN-melanin, requires the action of laccase enzymes. The T. marneffei genome encodes a number of laccases and this study describes the characterization of one of these, pbrB, during growth and development. A strain carrying a PbrB-GFP fusion shows that pbrB is expressed at high levels during asexual development (conidiation) but not in cells growing vegetatively. The pbrB gene is required for the synthesis of DHN-melanin in conidia and when deleted results in brown pigmented conidia, in contrast to the green conidia of the wild type.

  16. Non-invasive measurement of melanin-derived radicals in living mouse tail using X-band EPR

    PubMed Central

    Ogawa, Yukihiro; Ueno, Megumi; Sekine-Suzuki, Emiko; Nakanishi, Ikuo; Matsumoto, Ken-ichiro; Fujisaki, Shingo

    2016-01-01

    The aim of this experiment is to measure in vivo generation of melanin-derived radicals non-invasively, as a quantifiable index of radio-biological effect. Melanin-derived radicals in a living intact mouse tail tip were non-invasively measured in very simple way using an X-band electron paramagnetic resonance spectrometer. Colored mouse strains, C57BL/6NCr, BDF1, and C3H/He, have clear EPR signal corresponding to melanin-derived radicals in the tail tip; however, albino mouse strains, BALB/cCr, ddY, ICR, have no EPR signals. An X-ray fraction of 2 Gy/day (1 Gy/min) was repeatedly irradiated to a C3H/He mouse tail skin every Monday to Friday for 4 weeks. In comparison to before starting irradiation, the C3H/He mouse tail skin became darker, like a suntan. The melanin-derived radicals in C3H/He mouse tail skin were increased in association with X-ray fractions. Melanin-derived radicals in mouse tail skin can be readily and chronologically measurable by using X-band EPR spectrometer, and can be a marker for a radiobiological effect in the skin. PMID:27895382

  17. Ultrastructural changes produced in Ehrlich ascites carcinoma cells by ultraviolet-visible radiation in the presence of melanins

    SciTech Connect

    Lea, P.J.; Pawlowski, A.; Persad, S.D.; Menon, I.A.; Haberman, H.F.

    1988-01-01

    Irradiation of Ehrlich ascites carcinoma (EAC) cells in the presence of pheomelanin, i.e., red hair melanin (RHM), has been reported to produce extensive cell lysis. Irradiation in the presence of eumelanin, i.e., black hair melanin (BHM), or irradiation in the absence of either type of melanin did not produce this effect. We observed that RHM particles penetrated the cell membrane without apparent structural damage to the cell or the cell membrane. Irradiation of the cells in the absence of melanin did not produce any changes in the ultrastructure of the cells. Incubation of the cells in the dark in the presence of RHM produced only minor structural, mainly cytoplasmic changes. Irradiation of the cells in the presence of RHM produced extensive ultrastructural changes prior to complete cell lysis; these changes were more severe than the effects of incubation of the cells in the dark in the presence of RHM. When the cells incubated in the dark or irradiated in the presence of latex particles or either one of the eumelanins particles, viz. BHM or synthetic dopa melanin, these particles did not penetrate into the cells or produce any ultrastructural changes. These particles were in fact not even ingested by the cells.

  18. Inhibitory effects of adlay extract on melanin production and cellular oxygen stress in B16F10 melanoma cells.

    PubMed

    Huang, Huey-Chun; Hsieh, Wan-Yu; Niu, Yu-Lin; Chang, Tsong-Min

    2014-09-19

    The aim of this study was to determine the effects of adlay extract on melanin production and the antioxidant characteristics of the extract. The seeds were extracted by the supercritical fluid CO2 extraction (SFE) method. The effect of adlay extract on melanin production was evaluated using mushroom tyrosinase activity assay, intracellular tyrosinase activity, antioxidant properties and melanin content. Those assays were performed spectrophotometrically. In addition, the expression of melanogenesis-related proteins was determined by western blotting. The results revealed that the adlay extract suppressed intracellular tyrosinase activity and decreased the amount of melanin in B16F10 cells. The adlay extract decreased the expression of microphthalmia-associated transcription factor (MITF), tyrosinase, tyrosinase related protein-1 (TRP-1) and tyrosinase related protein-2 (TRP-2). The extract also exhibited antioxidant characteristics such as free radical scavenging capacity and reducing power. It effectively decreased intracellular reactive oxygen species (ROS) levels in B16F10 cells. We concluded that the adlay extract inhibits melanin production by down-regulation of MITF, tyrosinase, TRP-1 and TRP-2. The antioxidant properties of the extract may also contribute to the inhibition of melanogenesis. The adlay extract can therefore be applied as an inhibitor of melanogenesis and could also act as a natural antioxidant in skin care products.

  19. Inhibitory Effects of Adlay Extract on Melanin Production and Cellular Oxygen Stress in B16F10 Melanoma Cells

    PubMed Central

    Huang, Huey-Chun; Hsieh, Wan-Yu; Niu, Yu-Lin; Chang, Tsong-Min

    2014-01-01

    The aim of this study was to determine the effects of adlay extract on melanin production and the antioxidant characteristics of the extract. The seeds were extracted by the supercritical fluid CO2 extraction (SFE) method. The effect of adlay extract on melanin production was evaluated using mushroom tyrosinase activity assay, intracellular tyrosinase activity, antioxidant properties and melanin content. Those assays were performed spectrophotometrically. In addition, the expression of melanogenesis-related proteins was determined by western blotting. The results revealed that the adlay extract suppressed intracellular tyrosinase activity and decreased the amount of melanin in B16F10 cells. The adlay extract decreased the expression of microphthalmia-associated transcription factor (MITF), tyrosinase, tyrosinase related protein-1 (TRP-1) and tyrosinase related protein-2 (TRP-2). The extract also exhibited antioxidant characteristics such as free radical scavenging capacity and reducing power. It effectively decreased intracellular reactive oxygen species (ROS) levels in B16F10 cells. We concluded that the adlay extract inhibits melanin production by down-regulation of MITF, tyrosinase, TRP-1 and TRP-2. The antioxidant properties of the extract may also contribute to the inhibition of melanogenesis. The adlay extract can therefore be applied as an inhibitor of melanogenesis and could also act as a natural antioxidant in skin care products. PMID:25244016

  20. Real-time visualization of melanin granules in normal human skin using combined multiphoton and reflectance confocal microscopy.

    PubMed

    Majdzadeh, Ali; Lee, Anthony M D; Wang, Hequn; Lui, Harvey; McLean, David I; Crawford, Richard I; Zloty, David; Zeng, Haishan

    2015-05-01

    Recent advances in biomedical optics have enabled dermal and epidermal components to be visualized at subcellular resolution and assessed noninvasively. Multiphoton microscopy (MPM) and reflectance confocal microscopy (RCM) are noninvasive imaging modalities that have demonstrated promising results in imaging skin micromorphology, and which provide complementary information regarding skin components. This study assesses whether combined MPM/RCM can visualize intracellular and extracellular melanin granules in the epidermis and dermis of normal human skin. We perform MPM and RCM imaging of in vivo and ex vivo skin in the infrared domain. The inherent three-dimensional optical sectioning capability of MPM/RCM is used to image high-contrast granular features across skin depths ranging from 50 to 90 μm. The optical images thus obtained were correlated with conventional histologic examination including melanin-specific staining of ex vivo specimens. MPM revealed highly fluorescent granular structures below the dermal-epidermal junction (DEJ) region. Histochemical staining also demonstrated melanin-containing granules that correlate well in size and location with the granular fluorescent structures observed in MPM. Furthermore, the MPM fluorescence excitation wavelength and RCM reflectance of cell culture-derived melanin were equivalent to those of the granules. This study suggests that MPM can noninvasively visualize and quantify subepidermal melanin in situ. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  1. The pbrB Gene Encodes a Laccase Required for DHN-Melanin Synthesis in Conidia of Talaromyces (Penicillium) marneffei

    PubMed Central

    Sapmak, Ariya; Boyce, Kylie J.; Andrianopoulos, Alex; Vanittanakom, Nongnuch

    2015-01-01

    Talaromyces marneffei (Basionym: Penicillium marneffei) is a significant opportunistic fungal pathogen in patients infected with human immunodeficiency virus in Southeast Asia. T. marneffei cells have been shown to become melanized in vivo. Melanins are pigment biopolymers which act as a non-specific protectant against various stressors and which play an important role during virulence in fungi. The synthesis of the two most commonly found melanins in fungi, the eumelanin DOPA-melanin and the allomelanin DHN-melanin, requires the action of laccase enzymes. The T. marneffei genome encodes a number of laccases and this study describes the characterization of one of these, pbrB, during growth and development. A strain carrying a PbrB-GFP fusion shows that pbrB is expressed at high levels during asexual development (conidiation) but not in cells growing vegetatively. The pbrB gene is required for the synthesis of DHN-melanin in conidia and when deleted results in brown pigmented conidia, in contrast to the green conidia of the wild type. PMID:25866870

  2. Yolk testosterone shapes the expression of a melanin-based signal in great tits: an antioxidant-mediated mechanism?

    PubMed

    Galván, Ismael; Alonso-Alvarez, Carlos

    2010-09-15

    Conspicuous traits produced by melanin deposition in integuments are often involved in visual communication. The information content of melanin-based signals is unclear as their expression is tightly controlled by genes and, apparently, is less dependent on individual condition. In birds, high heritabilities have been attributed to melanin-based plumages, often on the basis of egg-swapping manipulations (cross-fostering experiments). However, it is well known that female birds can differentially transfer testosterone to the egg yolk. Furthermore, high testosterone levels have been related to high oxidative stress. As we recently found that oxidative stress experienced during development influences the expression of melanin-based traits, here we manipulated the level of yolk testosterone in great tits (Parus major) to assess the influence of this maternal effect on the expression of the black breast stripe, a well-known melanin-based signal. We predicted that fledglings hatched from eggs with high testosterone levels will not only show larger black stripes but also experience changes in their antioxidant machinery. Indeed, the size of the black stripe of great tits hatched from testosterone-injected eggs was almost double that of controls. Furthermore, the same individuals showed a trend to higher levels of circulating antioxidants, which suggests an adaptive response against some testosterone-induced oxidative challenge.

  3. pH-Induced aggregated melanin nanoparticles for photoacoustic signal amplification

    NASA Astrophysics Data System (ADS)

    Ju, Kuk-Youn; Kang, Jeeun; Pyo, Jung; Lim, Joohyun; Chang, Jin Ho; Lee, Jin-Kyu

    2016-07-01

    We present a new melanin-like nanoparticle (MelNP) and its performance evaluation results. This particle is proposed as an exogenous contrast agent for photoacoustic (PA) imaging. Conventional PA contrast agents are based on non-biological materials. In contrast, the MelNPs are organic nanoparticles inspired by natural melanin. Melanin is an endogenous chromophore that has the ability to produce a PA signal in vivo. The developed MelNPs are capable of aggregating with one another under mildly acidic conditions after introducing hydrolysis-susceptible citraconic amide on the surface of bare MelNPs. We ascertained that the physical aggregation of the MelNPs resulted in an increased PA signal strength in the near-infrared window of biological tissue (i.e., 700 nm) without absorption tuning. This phenomenon is likely because of the overlapping thermal fields of the developed MelNPs. The PA signal produced from the developed MelNPs, after exposure to mildly acidic conditions (i.e., pH 6), is 8.1 times stronger than under neutral conditions. This unique characteristic found in this study can be utilized in a practical strategy for highly sensitive in vivo cancer target imaging in response to its acidic microenvironment. This approach to amplify the PA response of MelNPs in clusters could accelerate the use of MelNPs as an alternative to non-biological nanoprobes, so that MelNPs may be applicable in PA imaging and functional PA imaging such as stimuli sensitive, multimodal, and theranostic imaging.We present a new melanin-like nanoparticle (MelNP) and its performance evaluation results. This particle is proposed as an exogenous contrast agent for photoacoustic (PA) imaging. Conventional PA contrast agents are based on non-biological materials. In contrast, the MelNPs are organic nanoparticles inspired by natural melanin. Melanin is an endogenous chromophore that has the ability to produce a PA signal in vivo. The developed MelNPs are capable of aggregating with one

  4. Transcription Factor Amr1 Induces Melanin Biosynthesis and Suppresses Virulence in Alternaria brassicicola

    SciTech Connect

    Cho, Yangrae; Srivastava, Akhil; Ohm, Robin A.; Lawrence, Christopher B.; Wang, Koon-Hui; Grigoriev, Igor V.; Marahatta, Sharadchandra P.

    2012-05-01

    Alternaria brassicicola is a successful saprophyte and necrotrophic plant pathogen. Several A. brassicicola genes have been characterized as affecting pathogenesis of Brassica species. To study regulatory mechanisms of pathogenesis, we mined 421 genes in silico encoding putative transcription factors in a machine-annotated, draft genome sequence of A. brassicicola. In this study, targeted gene disruption mutants for 117 of the transcription factor genes were produced and screened. Three of these genes were associated with pathogenesis. Disruption mutants of one gene (AbPacC) were nonpathogenic and another gene (AbVf8) caused lesions less than half the diameter of wild-type lesions. Unexpectedly, mutants of the third gene, Amr1, caused lesions with a two-fold larger diameter than the wild type and complementation mutants. Amr1 is a homolog of Cmr1, a transcription factor that regulates melanin biosynthesis in several fungi. We created gene deletion mutants of ?amr1 and characterized their phenotypes. The ?amr1 mutants used pectin as a carbon source more efficiently than the wild type, were melanin-deficient, and more sensitive to UV light and glucanase digestion. The AMR1 protein was localized in the nuclei of hyphae and in highly melanized conidia during the late stage of plant pathogenesis. RNA-seq analysis revealed that three genes in the melanin biosynthesis pathway, along with the deleted Amr1 gene, were expressed at low levels in the mutants. In contrast, many hydrolytic enzyme-coding genes were expressed at higher levels in the mutants than in the wild type during pathogenesis. The results of this study suggested that a gene important for survival in nature negatively affected virulence, probably by a less efficient use of plant cell-wall materials. We speculate that the functions of the Amr1 gene are important to the success of A. brassicicola as a competitive saprophyte and plant parasite.

  5. Transcription Factor Amr1 Induces Melanin Biosynthesis and Suppresses Virulence in Alternaria brassicicola

    PubMed Central

    Cho, Yangrae; Srivastava, Akhil; Ohm, Robin A.; Lawrence, Christopher B.; Wang, Koon-Hui; Grigoriev, Igor V.; Marahatta, Sharadchandra P.

    2012-01-01

    Alternaria brassicicola is a successful saprophyte and necrotrophic plant pathogen. Several A. brassicicola genes have been characterized as affecting pathogenesis of Brassica species. To study regulatory mechanisms of pathogenesis, we mined 421 genes in silico encoding putative transcription factors in a machine-annotated, draft genome sequence of A. brassicicola. In this study, targeted gene disruption mutants for 117 of the transcription factor genes were produced and screened. Three of these genes were associated with pathogenesis. Disruption mutants of one gene (AbPacC) were nonpathogenic and another gene (AbVf8) caused lesions less than half the diameter of wild-type lesions. Unexpectedly, mutants of the third gene, Amr1, caused lesions with a two-fold larger diameter than the wild type and complementation mutants. Amr1 is a homolog of Cmr1, a transcription factor that regulates melanin biosynthesis in several fungi. We created gene deletion mutants of Δamr1 and characterized their phenotypes. The Δamr1 mutants used pectin as a carbon source more efficiently than the wild type, were melanin-deficient, and more sensitive to UV light and glucanase digestion. The AMR1 protein was localized in the nuclei of hyphae and in highly melanized conidia during the late stage of plant pathogenesis. RNA-seq analysis revealed that three genes in the melanin biosynthesis pathway, along with the deleted Amr1 gene, were expressed at low levels in the mutants. In contrast, many hydrolytic enzyme-coding genes were expressed at higher levels in the mutants than in the wild type during pathogenesis. The results of this study suggested that a gene important for survival in nature negatively affected virulence, probably by a less efficient use of plant cell-wall materials. We speculate that the functions of the Amr1 gene are important to the success of A. brassicicola as a competitive saprophyte and plant parasite. PMID:23133370

  6. Candidate Gene Analysis Suggests Untapped Genetic Complexity in Melanin-Based Pigmentation in Birds.

    PubMed

    Bourgeois, Yann X C; Bertrand, Joris A M; Delahaie, Boris; Cornuault, Josselin; Duval, Thomas; Milá, Borja; Thébaud, Christophe

    2016-07-01

    Studies on melanin-based color variation in a context of natural selection have provided a wealth of information on the link between phenotypic and genetic variation. Here, we evaluated associations between melanic plumage patterns and genetic polymorphism in the Réunion grey white-eye (Zosterops borbonicus), a species in which mutations on MC1R do not seem to play any role in explaining melanic variation. This species exhibits 5 plumage color variants that can be grouped into 3 color forms which occupy discrete geographic regions in the lowlands of Réunion, and a fourth high-elevation form which comprises 2 color morphs (grey and brown) and represents a true color polymorphism. We conducted a comprehensive survey of sequence variation in 96 individuals at a series of 7 candidate genes other than MC1R that have been previously shown to influence melanin-based color patterns in vertebrates, including genes that have rarely been studied in a wild bird species before: POMC, Agouti, TYR, TYRP1, DCT, Corin, and SLC24A5 Of these 7 genes, 2 (Corin and TYRP1) displayed an interesting shift in allele frequencies between lowland and highland forms and a departure from mutation-drift equilibrium consistent with balancing selection in the polymorphic highland form only. Sequence variation at Agouti, a gene frequently involved in melanin-based pigmentation patterning, was not associated with color forms or morphs. Thus, we suggest that functionally important changes in loci other than those classically studied are involved in the color polymorphism exhibited by the Réunion grey white-eye and possibly many other nonmodel species. © The American Genetic Association. 2016. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  7. Dopamine-melanin film deposition depends on the used oxidant and buffer solution.

    PubMed

    Bernsmann, Falk; Ball, Vincent; Addiego, Frédéric; Ponche, Arnaud; Michel, Marc; Gracio, José Joaquin de Almeida; Toniazzo, Valérie; Ruch, David

    2011-03-15

    The deposition of "polydopamine" films, from an aqueous solution containing dopamine or other catecholamines, constitutes a new and versatile way to functionalize solid-liquid interfaces. Indeed such films can be deposited on almost all kinds of materials. Their deposition kinetics does not depend markedly on the surface chemistry of the substrate, and the films can reach thickness of a few tens of nanometers in a single reaction step. Up to now, even if a lot is known about the oxidation mechanism of dopamine in solution, only little information is available to describe the deposition mechanism on surfaces either by oxidation in solution or by electrodeposition. The deposition kinetics of melanin was only investigated from dopamine solutions using oxygen or ammonium persulfate as an oxidant and from a tris(hydroxymethyl) aminomethane (Tris) containing buffer solutions at pH 8.5. Many other oxidants could be used, and the buffer agent containing a primary amine group may influence the deposition process. Herein we show that the deposition kinetics of melanin from dopamine containing buffers at pH 8.5 can be markedly modified using Cu(2+) instead of O2 as an oxidant: the deposition kinetics remains linear up to thicknesses of more than 70 nm, whereas the film growth stops at 45 ± 5 nm in the presence of 02. In addition, the films prepared from Cu(2+) containing solutions display an absorption spectrum with defined peaks at 320 and 370 nm, which are absent in the spectra of films prepared in oxygenated solutions. The replacement of Tris buffer by phosphate buffer also has a marked effect on the melanin deposition kinetics.

  8. The allelochemical L-DOPA increases melanin production and reduces reactive oxygen species in soybean roots.

    PubMed

    Soares, Anderson Ricardo; de Lourdes Lucio Ferrarese, Maria; de Cássia Siqueira-Soares, Rita; Marchiosi, Rogério; Finger-Teixeira, Aline; Ferrarese-Filho, Osvaldo

    2011-08-01

    The non-protein amino acid, L-3,4-dihydroxyphenylalanine (L-DOPA), is the main allelochemical released from the roots of velvetbean and affects seed germination and root growth of several plant species. In the work presented here, we evaluated, in soybean roots, the effects of L-DOPA on the following: polyphenol oxidase (PPO), superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) activities; superoxide anion (O·-2), hydrogen peroxide (H(2)O(2)), and melanin contents; and lipid peroxidation. To this end, 3-day-old seedlings were cultivated in half-strength Hoagland's solution (pH 6.0), with or without 0.1 to 1.0 mM L-DOPA in a growth chamber (at 25°C, with a light/dark photoperiod of 12/12 hr and a photon flux density of 280 μmol m(-2) s(-1)) for 24 hr. The results showed that L-DOPA increased the PPO activity and, further, the melanin content. The activities of SOD and POD increased, but CAT activity decreased after the chemical exposure. The contents of reactive oxygen species (ROS), such as O·-2 and H(2)O(2), and the levels of lipid peroxidation significantly decreased under all concentrations of L-DOPA tested. These results suggest that L-DOPA was absorbed by the soybean roots and metabolized to melanin. It was concluded that the reduction in the O·-2 and H(2)O(2) contents and lipid peroxidation in soybean roots was due to the enhanced SOD and POD activities and thus a possible antioxidant role of L-DOPA.

  9. Monitoring the metabolic state of fungal hyphae and the presence of melanin by nonlinear spectral imaging.

    PubMed

    Knaus, Helene; Blab, Gerhard A; Agronskaia, Alexandra V; van den Heuvel, Dave J; Gerritsen, Hans C; Wösten, Han A B

    2013-10-01

    Label-free nonlinear spectral imaging microscopy (NLSM) records two-photon-excited fluorescence emission spectra of endogenous fluorophores within the specimen. Here, NLSM is introduced as a novel, minimally invasive method to analyze the metabolic state of fungal hyphae by monitoring the autofluorescence of NAD(P)H and flavin adenine dinucleotide (FAD). Moreover, the presence of melanin was analyzed by NLSM. NAD(P)H, FAD, and melanin were used as biomarkers for freshness of mushrooms of Agaricus bisporus (white button mushroom) that had been stored at 4°C for 0 to 17 days. During this period, the mushrooms did not show changes in morphology or color detectable by eye. In contrast, FAD/NAD(P)H and melanin/NAD(P)H ratios increased over time. For instance, these ratios increased from 0.92 to 2.02 and from 0.76 to 1.53, respectively, at the surface of mushroom caps that had been harvested by cutting the stem. These ratios were lower under the skin than at the surface of fresh mushrooms (0.78 versus 0.92 and 0.41 versus 0.76, respectively), indicative of higher metabolism and lower pigment formation within the fruiting body. Signals were different not only between tissues of the mushroom but also between neighboring hyphae. These data show that NLSM can be used to determine the freshness of mushrooms and to monitor the postharvest browning process at an early stage. Moreover, these data demonstrate the potential of NLSM to address a broad range of fundamental and applied microbiological processes.

  10. Suppression of melanin synthesis by the phenolic constituents of sappanwood (Caesalpinia sappan).

    PubMed

    Mitani, Kaoru; Takano, Fumihide; Kawabata, Tetsuro; Allam, Ahmed E; Ota, Mayumi; Takahashi, Tomoya; Yahagi, Nobuo; Sakurada, Chikai; Fushiya, Shinji; Ohta, Tomihisa

    2013-01-01

    Sappanwood (Caesalpinia sappan Linn.) is used as an herbal medicine. It is sometimes used to treat skin damage or as a facial cleanser. In the present study, the methanol (MeOH) extract of sappanwood was found to inhibit melanin synthesis in cultured human melanoma HMV-II cells stimulated with forskolin, and six active compounds (1-5 and 7) were isolated from the extract along with a non-active compound (6). Compounds 2-7 were identified as sappanchalcone (2), 3'-deoxy-4-O-methylsappanol (3), brazilein, (4), brazilin (5), sappanol (6), and 4-O-methylsappanol (7). Compound 1 was a new compound, and its structure was determined to be (6aS,11bR)-7,11b-dihydro-6H-indeno[2,1-c]chromene-3,6a,10,11-tetrol by spectroscopic analyses. Among the six active compounds, brazilin (5) (EC50: 3.0 ± 0.5 µM) and 4-O-methylsappanol (7) (EC50: 4.6 ± 0.7 µM) strongly suppressed melanin synthesis in HMV-II cells. Bioactive compounds showed moderate cytotoxicities against HMV-II cells with IC50 values of 83.1 ± 4.0 µM (for 2), 72.0 µM ± 2.4 (for 3), 33.8 ± 1.1 µM (for 4), 18.4 ± 0.8 µM (for 5), and 20.2 ± 0.8 (for 7), respectively. Brazilin (5) selectively suppressed the expression of mRNAs for tyrosinase-related protein (TYRP) 2 and tyrosinase but did not influence the expression of TYRP1. These results suggest that brazilin (5) is a new class of melanin inhibitor and that sappanwood could be used as a cosmetic material. Georg Thieme Verlag KG Stuttgart · New York.

  11. A multimodal assessment of melanin and melanocyte activity in abnormally pigmented hypertrophic scar.

    PubMed

    Travis, Taryn E; Ghassemi, Pejhman; Ramella-Roman, Jessica C; Prindeze, Nicholas J; Paul, Dereck W; Moffatt, Lauren T; Jordan, Marion H; Shupp, Jeffrey W

    2015-01-01

    Using a validated swine model of human scar formation, hyperpigmented and hypopigmented scar samples were examined for their histological and optical properties to help elucidate the mechanisms and characteristics of dyspigmentation. Full-thickness wounds were created on the flanks of red Duroc pigs and allowed to heal. Biopsies from areas of hyperpigmentation, hypopigmentation, and uninjured tissue were fixed and embedded for histological examination using Azure B and primary antibodies to S100B, HMB45, and α-melanocyte-stimulating hormone (α-MSH). Spatial frequency domain imaging (SFDI) was then used to examine the optical properties of scars. Hyperpigmentation was first noticeable in healing wounds around weeks 2 to 3, gradually becoming darker. There was no significant difference in S100B staining for the presence of melanocytes between hyperpigmented and hypopigmented scar samples. Azure B staining of melanin was significantly greater in histological sections from hyperpigmented areas than in sections from both uninjured skin and hypopigmented scar (P < .0001). There was significantly greater staining for α-MSH in hyperpigmented samples compared with hypopigmented samples (P = .0121), and HMB45 staining was positive for melanocytes in hyperpigmented scar. SFDI at a wavelength of 632 nm resulted in an absorption coefficient map correlating with visibly hyperpigmented areas of scars. In a red Duroc model of hypertrophic scar formation, melanocyte number is similar in hyperpigmented and hypopigmented tissues. Hyperpigmented tissues, however, show a greater amount of melanin and α-MSH, along with immunohistochemical evidence of stimulated melanocytes. These observations encourage further investigation of melanocyte stimulation and the inflammatory environment within a wound that may influence melanocyte activity. Additionally, SFDI can be used to identify areas of melanin content in mature, pigmented scars, which may lead to its usefulness in wounds at earlier

  12. New insights into the physicochemical effects of ammonia/peroxide bleaching of hair and Sepia melanins.

    PubMed

    Prem, Padmaja; Dube, Katherine J; Madison, Stephen A; Bartolone, John

    2003-01-01

    Chemically unaltered melanosomes from black hair were isolated using a mild enzymatic procedure reported by Novellino et al. involving sequential treatment of a homogenized hair sample with different protease enzymes. Time-dependent fluorescence studies show, under identical conditions, that the rate of bleaching upon NH3/H2O2 treatment of hair melanosomes is twice that of Sepia melanosomes. The structure and morphology of hair melanosomes are compared to Sepia eumelanin using ESEM and TEM imaging studies. Black hair melanosomes are aggregates of rice-shaped ellipsoidal particles (0.8-1.0 microm in length and 0.2-0.6 microm in width) surrounded by an amorphous material suspected to be made of non-proteinacious materials. Sepia eumelanin aggregates are larger (2-5 microm) particles with a "doughnut" shape comprised of 100-150-nm spherical particles. Time-dependent TEM imaging studies of ammonia-treated (pH 10) hair melanosomes showed an initial breakdown of melanosomal aggregates followed by rupture of the melanosomal membrane, releasing melanin nanoparticles and leaving a ghost membrane behind. After prolonged treatment with aqueous NH3, a total loss of characteristic melanosome morphology was observed leading to an amorphous material. By contrast, Sepia melanosomes under identical conditions of ammonia treatment did not show such changes, probably due to different surface properties and aggregation behavior. Sodium hydroxide or sodium carbonate at identical pH did not show similar changes to ammonia, suggesting that the changes are not merely due to alkaline pH, but, rather, are specific to ammonia. Co-treatment with ammonia and peroxide induced a faster disintegration of the melanosomes, resulting in a complete dissolution and discoloration of melanin in 30 minutes. The data suggest that ammonia helps to release melanin nanoparticles out of melanosomes, making them more susceptible to oxidative attack by H2O2.

  13. Duration of reappearance of gingival melanin pigmentation after surgical removal — A clinical study

    PubMed Central

    Kaur, Harjit; Jain, Sanjeev; Sharma, Roshan Lal

    2010-01-01

    Background: In dentistry, esthetics has a special place. Although gingival melanin pigmentation does not present a medical problem, clinicians are often faced with a challenge of achieving gingival esthetics. Materials and Methods: A method of de-epithelialization of the pigmented gingiva using Kirkland’s gingivectomy knife is described. Twenty patients who were conscious about their gingival melanin pigmentation were selected. The gingiva of the whole of the arch was abraded until the entire visible pigmentation was removed. Clinical observations for intensity of pigmentation were recorded at baseline and then after surgery at monthly intervals over a period of 9 months according to Dummett-Gupta Oral Pigmentation Index scoring criteria proposed by Dummett C. O. in 1964. Results: The mean gingival melanin pigmentation score came down to 0.407 after 9 months as compared to preoperative score, which was 2.24. No repigmentation occurred in fair-complexioned persons. In persons with wheatish complexion, repigmentation was seen in 85.71% of the cases, but scores came down to 0.38 postoperatively as compared to 2.27 preoperatively. In dark-complexioned persons, repigmentation occurred in all cases, but the mean scores were 0.93 as compared to 2.40 preoperatively. The difference between preoperative and postoperative mean scores for each segment was put to statistical analysis by applying paired t test and was found to be significant. Conclusion: As this method has shown statistically significant results, it can be used in patients who are conscious of pigmented gingiva and want an esthetically satisfactory color. PMID:21691546

  14. Monitoring the Metabolic State of Fungal Hyphae and the Presence of Melanin by Nonlinear Spectral Imaging

    PubMed Central

    Knaus, Helene; Blab, Gerhard A.; Agronskaia, Alexandra V.; van den Heuvel, Dave J.; Gerritsen, Hans C.

    2013-01-01

    Label-free nonlinear spectral imaging microscopy (NLSM) records two-photon-excited fluorescence emission spectra of endogenous fluorophores within the specimen. Here, NLSM is introduced as a novel, minimally invasive method to analyze the metabolic state of fungal hyphae by monitoring the autofluorescence of NAD(P)H and flavin adenine dinucleotide (FAD). Moreover, the presence of melanin was analyzed by NLSM. NAD(P)H, FAD, and melanin were used as biomarkers for freshness of mushrooms of Agaricus bisporus (white button mushroom) that had been stored at 4°C for 0 to 17 days. During this period, the mushrooms did not show changes in morphology or color detectable by eye. In contrast, FAD/NAD(P)H and melanin/NAD(P)H ratios increased over time. For instance, these ratios increased from 0.92 to 2.02 and from 0.76 to 1.53, respectively, at the surface of mushroom caps that had been harvested by cutting the stem. These ratios were lower under the skin than at the surface of fresh mushrooms (0.78 versus 0.92 and 0.41 versus 0.76, respectively), indicative of higher metabolism and lower pigment formation within the fruiting body. Signals were different not only between tissues of the mushroom but also between neighboring hyphae. These data show that NLSM can be used to determine the freshness of mushrooms and to monitor the postharvest browning process at an early stage. Moreover, these data demonstrate the potential of NLSM to address a broad range of fundamental and applied microbiological processes. PMID:23934488

  15. Enzymatic synthesis of arbutin undecylenic acid ester and its inhibitory effect on melanin synthesis.

    PubMed

    Tokiwa, Yutaka; Kitagawa, Masaru; Raku, Takao; Yanagitani, Shusaku; Yoshino, Kenji

    2007-06-01

    Transesterification of arbutin and undecylenic acid vinyl ester was catalyzed by alkaline protease, Bioprase, in dimethylformamide to get arbutin derivative having undecylenic acid at 6-position of glucose moiety, 6-O-undecylenoyl p-hydroxyphenyl beta-D-glucopyranoside. The reaction rate increased with increase of arbutin concentration, and when its concentration was 0.9 M, the conversion rate was more than 90% under addition of 2 M undecylenic acid vinyl ester. The obtained arbutin ester significantly suppressed melanin production in murine B16 melanoma cells.

  16. Potent inhibitors of tyrosinase activity and melanin biosynthesis from Rheum officinale.

    PubMed

    Iida, K; Hase, K; Shimomura, K; Sudo, S; Kadota, S; Namba, T

    1995-10-01

    Thirty-three crude drug extracts were screened for their tyrosinase inhibitory activity. Among them, the acetone extract of the rhizomes of Rheum officinale Baillon showed the strongest inhibitory activity. Tyrosinase inhibitory activity-guided fractionation and chemical analysis led to the isolation of two potent compounds, 3,4',5-trihydroxystilbene-4'-O-beta-D-(2"-O-galloyl)glucopyr anoside (1) and 3,4',5-trihydroxystilbene-4'-O-beta-D-(6"-O-galloyl)glucopyr anoside (2). These compounds showed a competitive inhibition against tyrosinase and also inhibited the melanin biosynthesis.

  17. L-dihidroxyphenylalanine induces melanin production by members of the genus Trichosporon

    PubMed Central

    de Carvalho, Maria Helena Galdino Figueiredo; dos Santos, Fábio Brito; Nosanchuk, Joshua D.; Zancope-Oliveira, Rosely M.; Almeida-Paes, Rodrigo

    2014-01-01

    Melanization of members of the genus Trichosporon is poorly described. In the present study six strains, including two clinical isolates, from four different species (T. asahii, T. asteroides, T. inkin, and T. mucoides) were grown in culture media with or without L-dihydroxyphenilalanine (L-DOPA). Each strain produced a brownish pigment compatible with melanin when cultured in presence of L-DOPA, suggesting that these species are able to produce eumelanin. L-tyrosine was not able to elicit any type of pigment production on cultures. Since eumelanin is produced by several fungi during parasitism, this pigment may contribute to Trichosporon virulence. PMID:24920288

  18. Design and optimization of quinazoline derivatives as melanin concentrating hormone receptor 1 (MCHR1) antagonists.

    PubMed

    Sasmal, Sanjita; Balaji, Gade; Kanna Reddy, Hariprasada R; Balasubrahmanyam, D; Srinivas, Gujjary; Kyasa, Shivakumar; Sasmal, Pradip K; Khanna, Ish; Talwar, Rashmi; Suresh, J; Jadhav, Vikram P; Muzeeb, Syed; Shashikumar, Dhanya; Harinder Reddy, K; Sebastian, V J; Frimurer, Thomas M; Rist, Øystein; Elster, Lisbeth; Högberg, Thomas

    2012-05-01

    Melanin concentrating hormone (MCH) is an important mediator of energy homeostasis and plays a role in metabolic and CNS disorders. The modeling-supported design, synthesis and multi-parameter optimization (biological activity, solubility, metabolic stability, hERG) of novel quinazoline derivatives as MCHR1 antagonists are described. The in vivo proof of principle for weight loss with a lead compound from this series is exemplified. Clusters of refined hMCHR1 homology models derived from the X-ray structure of the β2-adrenergic receptor, including extracellular loops, were developed and used to guide the design.

  19. Using Sepia melanin as a PD model to describe the binding characteristics of neuromelanin - A critical review.

    PubMed

    Schroeder, Rhiannon L; Double, Kay L; Gerber, Jacobus P

    2015-01-01

    Parkinson's disease is characterised pathologically by a relatively selective death of dopaminergic neurons in the substantia nigra of the brain. The vulnerability of these neurons appears to be linked to the pigment neuromelanin. However, as yet there is limited understanding behind the mechanisms of this disease process. Complications arise due to the difficulty in obtaining appreciable quantities of neuromelanin. Furthermore, an appropriate model for studying neuromelanin has not been identified. To date there has been many studies looking at the binding and chemical characteristics of neuromelanin. However, a range of different synthetic and organic melanins have been used as models and leading to many varied conclusions being drawn. Therefore, the aim of this review is to present Sepia melanin as the most appropriate study model for the binding characteristics of neuromelanin. Considerations included chemical structure, surface characteristics and structural features of both synthetic and organic melanins.

  20. Melanin synthesis is associated with changes in hyphopodial turgor, permeability, and wall rigidity in gaeumannomyces graminis var. graminis.

    PubMed

    Money, N P; Caesar-TonThat, T C; Frederick, B; Henson, J M

    1998-01-01

    Mycelia of Gaeumannomyces graminis var. graminis form large cells called hyphopodia with deeply lobed, melanized walls. Like appressoria produced by other pathogens, hyphopodia develop on hydrophobic surfaces, but it is not clear that hyphopodia function as platforms for host penetration. In appressoria, melanin synthesis is linked to the generation of enormous turgor pressures that provide the necessary force for plant penetration. In the present study, hyphopodial turgor was measured in a wild-type strain of G. graminis var. graminis, a mutant exhibiting constitutive synthesis of melanin (referred to as the dark mutant), and a melanin-deficient strain (thr). These experiments demonstrate that hyphopodia of the wild-type strain generate higher pressures than the dark mutant and that nonmelanized thr hyphopodia generate minuscule internal pressures. Melanization of the wall is also associated with an increase in its rigidity. These data correlate with differences in wall permeability consistent with a recent model for turgor generation by appressoria.

  1. EPR examination of free radical properties of DOPA-melanin complexes with ciprofloxacin, lomefloxacin, norfloxacin and sparfloxacin

    NASA Astrophysics Data System (ADS)

    Beberok, Artur; Buszman, Ewa; Zdybel, Magdalena; Pilawa, Barbara; Wrześniok, Dorota

    2010-09-01

    Paramagnetic complexes of DOPA-melanin with ciprofloxacin, lomefloxacin, norfloxacin and sparfloxacin were studied by EPR spectroscopy. The aim of this work was to determine free radical concentration and properties of these complexes. Free radical concentrations in the studied complexes were ∼1019-1020 spin/g. Relatively lower and similar (5.1-6.6 × 1019 spin/g) free radical concentrations characterized DOPA-melanin complexes with ciprofloxacin, and lomefloxacin. Higher concentrations (0.8-1.2 × 1020 spin/g) were obtained for complexes of norfloxacin and sparfloxacin. Effect of the drug concentration on free radicals in melanin was observed. Strong dipolar spin-spin interactions and slow spin-lattice relaxation processes exist in all of the samples.

  2. Inhibitory components from the buds of clove (Syzygium aromaticum) on melanin formation in B16 melanoma cells.

    PubMed

    Arung, Enos Tangke; Matsubara, Eri; Kusuma, Irawan Wijaya; Sukaton, Edi; Shimizu, Kuniyoshi; Kondo, Ryuichiro

    2011-03-01

    In the course to find a new whitening agent, we evaluated the methanol extract from bud of clove (Syzygium aromaticum) on melanin formation in B16 melanoma cells. Eugenol and eugenol acetate were isolated as the active compounds and showed melanin inhibition of 60% and 40% in B16 melanoma cell with less cytotoxicity at the concentration of 100 and 200 μg/mL, respectively. Furthermore, an essential oil prepared from the bud of clove, which contain eugenol and eugenol acetate as dominant components, showed melanin inhibition of 50% and 80% in B16 melanoma cells at the concentration of 100 and 200 μg/mL, respectively. Copyright © 2010 Elsevier B.V. All rights reserved.

  3. Melanin and blood concentration in a human skin model studied by multiple regression analysis: assessment by Monte Carlo simulation.

    PubMed

    Shimada, M; Yamada, Y; Itoh, M; Yatagai, T

    2001-09-01

    Measurement of melanin and blood concentration in human skin is needed in the medical and the cosmetic fields because human skin colour is mainly determined by the colours of melanin and blood. It is difficult to measure these concentrations in human skin because skin has a multi-layered structure and scatters light strongly throughout the visible spectrum. The Monte Carlo simulation currently used for the analysis of skin colour requires long calculation times and knowledge of the specific optical properties of each skin layer. A regression analysis based on the modified Beer-Lambert law is presented as a method of measuring melanin and blood concentration in human skin in a shorter period of time and with fewer calculations. The accuracy of this method is assessed using Monte Carlo simulations.

  4. Melanin and blood concentration in a human skin model studied by multiple regression analysis: assessment by Monte Carlo simulation

    NASA Astrophysics Data System (ADS)

    Shimada, M.; Yamada, Y.; Itoh, M.; Yatagai, T.

    2001-09-01

    Measurement of melanin and blood concentration in human skin is needed in the medical and the cosmetic fields because human skin colour is mainly determined by the colours of melanin and blood. It is difficult to measure these concentrations in human skin because skin has a multi-layered structure and scatters light strongly throughout the visible spectrum. The Monte Carlo simulation currently used for the analysis of skin colour requires long calculation times and knowledge of the specific optical properties of each skin layer. A regression analysis based on the modified Beer-Lambert law is presented as a method of measuring melanin and blood concentration in human skin in a shorter period of time and with fewer calculations. The accuracy of this method is assessed using Monte Carlo simulations.

  5. Plumage coloration and nutritional condition in the great tit Parus major: the roles of carotenoids and melanins differ

    NASA Astrophysics Data System (ADS)

    Senar, Juan Carlos; Figuerola, Jordi; Domènech, Jordi

    2003-05-01

    The size and coloration of some body characters seem to influence mate choice in many species. Most animal colours are either structural or based on melanin or carotenoid pigments. It has recently been suggested that carotenoid-based or structural coloration may be a condition-dependent trait, whereas melanin-based coloration is not; a difference that may be highly relevant when studying the evolution of multiple mating preferences. We tested this hypothesis in the great tit ( Parus major). The size of the melanin breast band was not correlated to nutritional condition as estimated by the rate of tail growth (ptilochronology), controlling for locality, age, sex, year and season effects. However, the correlation was significant for the hue of yellow breast (carotenoid-based coloration), and the slopes of the regressions of the two pigments to growth bars differed significantly. These results suggest that the expression of the two traits may be regulated by different mechanisms.

  6. High-Throughput Melanin-Binding Affinity and In Silico Methods to Aid in the Prediction of Drug Exposure in Ocular Tissue.

    PubMed

    Reilly, John; Williams, Sarah L; Forster, Cornelia J; Kansara, Viral; End, Peter; Serrano-Wu, Michael H

    2015-12-01

    Drugs possessing the ability to bind to melanin-rich tissue, such as the eye, are linked with higher ocular exposure, and therefore have the potential to affect the efficacy and safety profiles of therapeutics. A high-throughput melanin chromatographic affinity assay has been developed and validated, which has allowed the rapid melanin affinity assessment for a large number of compounds. Melanin affinity of compounds can be quickly assigned as low, medium, or high melanin binders. A high-throughput chromatographic method has been developed and fully validated to assess melanin affinity of pharmaceuticals and has been useful in predicting ocular tissue distribution in vivo studies. The high-throughput experimental approach has also allowed for a specific training set of 263 molecules for a quantitative structure-affinity relationships (QSAR) method to be developed, which has also been shown to be a predictor of ocular tissue exposure. Previous studies have reported the development of in silico QSAR models based on training sets of relatively small and mostly similar compounds; this model covers a broader range of melanin-binding affinities than what has been previously published and identified several physiochemical descriptors to be considered in the design of compounds where melanin-binding modulation is desired.

  7. The Aspergillus fumigatus conidial melanin production is regulated by the bifunctional bHLH DevR and MADS-box RlmA transcription factors.

    PubMed

    Valiante, Vito; Baldin, Clara; Hortschansky, Peter; Jain, Radhika; Thywißen, Andreas; Straßburger, Maria; Shelest, Ekaterina; Heinekamp, Thorsten; Brakhage, Axel A

    2016-10-01

    Melanins play a crucial role in defending organisms against external stressors. In several pathogenic fungi, including the human pathogen Aspergillus fumigatus, melanin production was shown to contribute to virulence. A. fumigatus produces two different types of melanins, i.e., pyomelanin and dihydroxynaphthalene (DHN)-melanin. DHN-melanin forms the gray-green pigment characteristic for conidia, playing an important role in immune evasion of conidia and thus for fungal virulence. The DHN-melanin biosynthesis pathway is encoded by six genes organized in a cluster with the polyketide synthase gene pksP as a core element. Here, cross-species promoter analysis identified specific DNA binding sites in the DHN-melanin biosynthesis genes pksP-arp1 intergenic region that can be recognized by bHLH and MADS-box transcriptional regulators. Independent deletion of two genes coding for the transcription factors DevR (bHLH) and RlmA (MADS-box) interfered with sporulation and reduced the expression of the DHN-melanin gene cluster. In vitro and in vivo experiments proved that these transcription factors cooperatively regulate pksP expression acting both as repressors and activators in a mutually exclusive manner. The dual role executed by each regulator depends on specific DNA motifs recognized in the pksP promoter region. © 2016 John Wiley & Sons Ltd.

  8. Graphic analysis of the relationship between skin colour change and variations in the amounts of melanin and haemoglobin.

    PubMed

    Takiwaki, H; Miyaoka, Y; Kohno, H; Arase, S

    2002-05-01

    The L*a*b* coordinate is the most commonly used colour system to measure skin colour in dermatology and cosmetology. In this system, a* and L* are often used for quantification of the degrees of erythema and pigmentation. The aim of this study was to examine whether a* and L* can be used as specific scales to indicate the amount of haemoglobin and melanin, respectively, in the skin. The a* and L* values were examined with a reflectance spectrometer in various skin conditions or lesions caused by a change in the amount of either melanin or haemoglobin, i.e. vitiligo, ultraviolet-induced pigmentation (PG), erythema resulting from slapping (ER), corticosteroid-induced blanching, erythema due to stasis by arm lowering, and a combination of PG and ER. The differences in values between the test sites and the adjacent normal skin, deltaa* and deltaL*, were plotted on the deltaa*-deltaL* plane and analysed statistically and geometrically. L* depended substantially not only on melanin but also on haemoglobin, especially if the oxygen saturation level was expected to be low. a* was also influenced by melanin. The results of graphic analysis indicated that a linear transformation of (deltaa*, deltaL*) into (deltaHb = 1.68 deltaa* + 0.60 deltaL*, deltaMel =-1.06 deltaa*-1.44 deltaL*) was suitable for separately estimating the change in the amount of haemoglobin (deltaHb) and in that of melanin (deltaMel). The results of this study may be of value for understanding the relationship between colour coordinates of the skin and the quantities of haemoglobin and melanin, and may be of use when pigmented lesions of the face are monitored by tristimulus colourimetry, as facial skin colour is affected considerably by the rich and easily variable cutaneous blood flow.

  9. Protein adsorption on dopamine-melanin films: role of electrostatic interactions inferred from zeta-potential measurements versus chemisorption.

    PubMed

    Bernsmann, Falk; Frisch, Benoît; Ringwald, Christian; Ball, Vincent

    2010-04-01

    We recently showed the possibility to build dopamine-melanin films of controlled thickness by successive immersions of a substrate in alkaline solutions of dopamine [F. Bernsmann, A. Ponche, C. Ringwald, J. Hemmerlé, J. Raya, B. Bechinger, J.-C. Voegel, P. Schaaf, V. Ball, J. Phys. Chem. C 113 (2009) 8234-8242]. In this work the structure and properties of such films are further explored. The zeta-potential of dopamine-melanin films is measured as a function of the total immersion time to build the film. It appears that the film bears a constant zeta-potential of (-39+/-3) mV after 12 immersion steps. These data are used to calculate the surface density of charged groups of the dopamine-melanin films at pH 8.5 that are mostly catechol or quinone imine chemical groups. Furthermore the zeta-potential is used to explain the adsorption of three model proteins (lysozyme, myoglobin, alpha-lactalbumin), which is monitored by quartz crystal microbalance. We come to the conclusion that protein adsorption on dopamine-melanin is not only determined by possible covalent binding between amino groups of the proteins and catechol groups of dopamine-melanin but that electrostatic interactions contribute to protein binding. Part of the adsorbed proteins can be desorbed by sodium dodecylsulfate solutions at the critical micellar concentration. The fraction of weakly bound proteins decreases with their isoelectric point. Additionally the number of available sites for covalent binding of amino groups on melanin grains is quantified.

  10. Simultaneous in vivo imaging of melanin and lipofuscin in the retina with photoacoustic ophthalmoscopy and autofluorescence imaging

    NASA Astrophysics Data System (ADS)

    Zhang, Xiangyang; Zhang, Hao F.; Puliafito, Carmen A.; Jiao, Shuliang

    2011-08-01

    We combined photoacoustic ophthalmoscopy (PAOM) with autofluorescence imaging for simultaneous in vivo imaging of dual molecular contrasts in the retina using a single light source. The dual molecular contrasts come from melanin and lipofuscin in the retinal pigment epithelium (RPE). Melanin and lipofuscin are two types of pigments and are believed to play opposite roles (protective versus exacerbate) in the RPE in the aging process. We have successfully imaged the retina of pigmented and albino rats at different ages. The experimental results showed that multimodal PAOM system can be a potentially powerful tool in the study of age-related degenerative retinal diseases.

  11. Quantitative photoluminescence of broad band absorbing melanins: a procedure to correct for inner filter and re-absorption effects

    NASA Astrophysics Data System (ADS)

    Riesz, Jennifer; Gilmore, Joel; Meredith, Paul

    2005-07-01

    We report methods for correcting the photoluminescence emission and excitation spectra of highly absorbing samples for re-absorption and inner filter effects. We derive the general form of the correction, and investigate various methods for determining the parameters. Additionally, the correction methods are tested with highly absorbing fluorescein and melanin (broadband absorption) solutions; the expected linear relationships between absorption and emission are recovered upon application of the correction, indicating that the methods are valid. These procedures allow accurate quantitative analysis of the emission of low quantum yield samples (such as melanin) at concentrations where absorption is significant.

  12. Inhibitory effects of flavonoid glycosides isolated from the peel of Japanese persimmon (Diospyros kaki 'Fuyu') on melanin biosynthesis.

    PubMed

    Ohguchi, Kenji; Nakajima, Chizuru; Oyama, Masayoshi; Iinuma, Munekazu; Itoh, Tomohiro; Akao, Yukihiro; Nozawa, Yoshinori; Ito, Masafumi

    2010-01-01

    We found that the acetone extract of the peel of Japanese persimmon (Diospyros kaki 'Fuyu') inhibits melanin biosynthesis in mouse B16 melanoma cells. The activity-guided purification of the extract resulted in isolation of two active compounds, which have been identified as flavonoid glycosides, isoquercitrin (quercetin-3-O-glucoside) and hyperin (quercetin-3-O-galactoside) by spectral analysis. Isoquercitrin and hyperin strongly inhibited the production of melanin (IC(50): 21.7 and 18.2 microM, respectively). The inhibitory effects were found to be mediated by suppression of tyrosinase expression.

  13. Olanzapine-induced changes in glucose metabolism are independent of the melanin-concentrating hormone system.

    PubMed

    Girault, Elodie M; Toonen, Pim W; Eggels, Leslie; Foppen, Ewout; Ackermans, Mariëtte T; la Fleur, Susanne E; Fliers, Eric; Kalsbeek, Andries

    2013-11-01

    Atypical antipsychotic drugs such as Olanzapine (Ola) induce weight gain and metabolic changes associated with the development of type 2 diabetes. The mechanisms underlying these undesired side-effects are currently unknown. Chagnon et al. showed that the common allele rs7973796 of the prepro-melanin-concentrating hormone (PMCH) gene is associated with a greater body mass index in Ola-treated schizophrenic patients. As PMCH encodes for the orexigenic neuropeptide melanin-concentrating hormone (MCH), it was hypothesized that MCH is involved in Ola-induced metabolic changes. We have recently reported that the intragastric infusion of Ola results in hyperglycaemia and insulin resistance in male rats. In order to test in vivo the possible involvement of the PMCH gene in the pathogenesis of Ola side-effects, we administered Ola intragastrically in wild-type (WT) and PMCH knock-out (KO) rats. Our results show that glucose and corticosterone levels, as well as endogenous glucose production, are elevated by the infusion of Ola in both WT and KO animals. Thus, the lack of MCH does not seem to affect the acute effects of Ola on glucose metabolism. On the other hand, these effects might be obliterated by compensatory changes in other hypothalamic systems. In addition, possible modulatory effects of the MCH KO on the long term effects of Ola, i.e. increased adiposity, body weight gain, have not been investigated yet.

  14. Melanin Transfer in Human 3D Skin Equivalents Generated Exclusively from Induced Pluripotent Stem Cells

    PubMed Central

    Gledhill, Karl; Guo, Zongyou; Umegaki-Arao, Noriko; Higgins, Claire A.; Itoh, Munenari; Christiano, Angela M.

    2015-01-01

    The current utility of 3D skin equivalents is limited by the fact that existing models fail to recapitulate the cellular complexity of human skin. They often contain few cell types and no appendages, in part because many cells found in the skin are difficult to isolate from intact tissue and cannot be expanded in culture. Induced pluripotent stem cells (iPSCs) present an avenue by which we can overcome this issue due to their ability to be differentiated into multiple cell types in the body and their unlimited growth potential. We previously reported generation of the first human 3D skin equivalents from iPSC-derived fibroblasts and iPSC-derived keratinocytes, demonstrating that iPSCs can provide a foundation for modeling a complex human organ such as skin. Here, we have increased the complexity of this model by including additional iPSC-derived melanocytes. Epidermal melanocytes, which are largely responsible for skin pigmentation, represent the second most numerous cell type found in normal human epidermis and as such represent a logical next addition. We report efficient melanin production from iPSC-derived melanocytes and transfer within an entirely iPSC-derived epidermal-melanin unit and generation of the first functional human 3D skin equivalents made from iPSC-derived fibroblasts, keratinocytes and melanocytes. PMID:26308443

  15. Topical liposome targeting of dyes, melanins, genes, and proteins selectively to hair follicles.

    PubMed

    Hoffman, R M

    1998-01-01

    For therapeutic and cosmetic modification of hair, we have developed a hair-follicle-selective macromolecule and small molecule targeting system with topical application of phosphatidylcholine-based liposomes. Liposome-entrapped melanins, proteins, genes, and small-molecules have been selectively targeted to the hair follicle and hair shafts of mice. Liposomal delivery of these molecules is time dependent. Negligible amounts of delivered molecules enter the dermis, epidermis, or bloodstream thereby demonstrating selective follicle delivery. Naked molecules are trapped in the stratum corneum and are unable to enter the follicle. The potential of the hair-follicle liposome delivery system for therapeutic use for hair disease as well as for cosmesis has been demonstrated in 3-dimensional histoculture of hair-growing skin and mouse in vivo models. Topical liposome selective delivery to hair follicles has demonstrated the ability to color hair with melanin, the delivery of the active lac-Z gene to hair matrix cells and delivery of proteins as well. Liposome-targeting of molecules to hair follicles has also been achieved in human scalp in histoculture. Liposomes thus have high potential in selective hair follicle targeting of large and small molecules, including genes, opening the field of gene therapy and other molecular therapy of the hair process to restore hair growth, physiologically restore or alter hair pigment, and to prevent or accelerate hair loss.

  16. Microneedling dilates the follicular infundibulum and increases transfollicular absorption of liposomal sepia melanin

    PubMed Central

    Serrano, Gabriel; Almudéver, Patricia; Serrano, Juan M; Cortijo, Julio; Faus, Carmen; Reyes, Magda; Expósito, Inmaculada; Torrens, Ana; Millán, Fernando

    2015-01-01

    Encapsulation of chemicals in liposomes and microneedling are currently used techniques to enhance the penetration of several substances through skin and hair. In this study, we apply a liposomal melanin–fluorescein compound to an ex vivo model of human skin, using a new electrical microneedling device (Nanopore turbo roller). The product was applied by hand massage (A) or with the assistance of the electrical roller for 2 minutes (B). An additional test was performed free of product and with only the E-roller (C). Histological changes and product absorption were evaluated by optical and fluorescent microscopy 60 and 90 minutes after the treatment. Site B showed larger deposits of melanin–fluorescein at superficial and deep levels of hair structures in comparison to site A. Light, epidermal deposits of the melanin–fluorescein complex were also observed. Sites B and C showed a significant widening (47%) of the follicular infundibulum which could explain the increased penetration of the formulation. Microneedling also removed the scales and sebum residues in the neighborhood of the infundibulum. Targeting hair follicles with melanin may be useful to dye poorly pigmented hairs, improving laser hair removal. The procedure accelerates the delivery of melanin into hair structures allowing an even absorption, larger pigment deposits, and deeper penetration of the formulation into the hair. PMID:26170707

  17. Effects of melanin-induced free radicals on the isolated rat peritoneal mast cells

    SciTech Connect

    Ranadive, N.S.; Shirwadkar, S.; Persad, S.; Menon, I.A.

    1986-03-01

    Pheomelanin from human red hair (RHM) produces considerably more cellular damage in Ehrlich ascites carcinoma cells when subjected to radiations of wavelength 320-700 nm than eumelanin from black hair (BHM). Irradiation of RHM generated large amounts of superoxide while BHM did not produce detectable amounts of superoxide. The present investigations describe the effects of irradiation of mast cells in the presence of various natural and synthetic melanins. Irradiation of mast cells in the presence of RHM and red hair melanoprotein released large amounts of histamine while BHM and synthetic melanins prepared from dopa, cysteinyldopa, or a mixture of dopa and cysteinyldopa did not release histamine. The release of histamine at lower concentrations of RHM was not accompanied by the release of /sup 51/Cr from chromium-loaded cells, suggesting that this release was of noncytotoxic nature. On the other hand, the release of histamine at higher concentrations of RHM was due to cell lysis since both histamine and cytoplasmic marker /sup 51/Cr were released to the same extent. The release evoked by large concentration RHM was not inhibited by superoxide dismutase or catalase. This suggests that the cell lysis under these conditions was not due to H/sub 2/O/sub 2/ or O-2. The finding that mast cells release histamine when irradiated in the presence of RHM suggests that the immediate and late-phase reactions seen in sunburn may in part be due to the release of mediators from these cells.

  18. Effect of norfloxacin and moxifloxacin on melanin synthesis and antioxidant enzymes activity in normal human melanocytes.

    PubMed

    Beberok, Artur; Wrześniok, Dorota; Otręba, Michał; Miliński, Maciej; Rok, Jakub; Buszman, Ewa

    2015-03-01

    Fluoroquinolone antibiotics provide broad-spectrum coverage for a number of infectious diseases, including respiratory as well as urinary tract infections. One of the important adverse effects of these drugs is phototoxicity which introduces a serious limitation to their use. To gain insight the molecular mechanisms underlying the fluoroquinolones-induced phototoxic side effects, the impact of two fluoroquinolone derivatives with different phototoxic potential, norfloxacin and moxifloxacin, on melanogenesis and antioxidant enzymes activity in normal human melanocytes HEMa-LP was determined. Both drugs induced concentration-dependent loss in melanocytes viability. The value of EC50 for these drugs was found to be 0.5 mM. Norfloxacin and moxifloxacin suppressed melanin biosynthesis; antibiotics were shown to inhibit cellular tyrosinase activity and to reduce melanin content in melanocytes. When comparing the both analyzed fluoroquinolones, it was observed that norfloxacin possesses greater inhibitory effect on tyrosinase activity in melanocytes than moxifloxacin. The extent of oxidative stress in cells was assessed by measuring the activity of antioxidant enzymes: SOD, CAT, and GPx. It was observed that norfloxacin caused higher depletion of antioxidant status in melanocytes when compared with moxifloxacin. The obtained results give a new insight into the mechanisms of fluoroquinolones toxicity directed to pigmented tissues. Moreover, the presented differences in modulation of biochemical processes in melanocytes may be an explanation for various phototoxic activities of the analyzed fluoroquinolone derivatives in vivo.

  19. Action of 2,2',4,4'-tetrahydroxybenzophenone in the biosynthesis pathway of melanin.

    PubMed

    Garcia-Jimenez, Antonio; Teruel-Puche, Jose Antonio; Garcia-Ruiz, Pedro Antonio; Berna, Jose; Rodríguez-López, Jose Neptuno; Tudela, Jose; Garcia-Canovas, Francisco

    2017-05-01

    2,2',4,4'-tetrahydroxybenzophenone (Uvinul D50), a sunscreen used in cosmetics, has two effects in the melanin biosynthesis pathway. On the one hand, it acts a weak inhibitor of tyrosinase and on the other, it accelerates the conversion of dopachrome to melanin. Uvinul D50 was seen to behave as a weak competitive inhibitor: apparent constant inhibition=2.02±0.09mM and IC50=3.82±0.39mM established in this work. These values are higher than those in the bibliography, which tend to be undersetimated. This discrepancy could be explained by the reaction of Uvinul D50 with the dopachrome produced from l-tyrosine or l-dopa, which would interfere in the measurement. Based on studies of its docking to tyrosinase, it seems that Uvinul D50 interacts with the active site of the enzyme (oxytyrosinase) both in its protonated and deprotonated forms (pKa=7). However, it cannot be hydroxylated, meaning that it acts as a weak inhibitor, not as an alternative substrate, despite its resorcinol structure. Uvinul D50 can be used as sunscreen, in low concentrations without significant adverse effects on melanogenesis.

  20. The adaptive function of melanin-based plumage coloration to trace metals

    PubMed Central

    Chatelain, M.; Gasparini, J.; Jacquin, L.; Frantz, A.

    2014-01-01

    Trace metals produced by anthropogenic activities are of major importance in urban areas and might constitute a new evolutionary force selecting for the ability to cope with their deleterious effects. Interestingly, melanin pigments are known to bind metal ions, thereby potentially sequestering them in inert body parts such as coat and feathers, and facilitating body detoxification. Thus, a more melanic plumage or coat coloration could bring a selective advantage for animals living in polluted areas. We tested this hypothesis by investigating the link between melanin-based coloration and zinc and lead concentrations in feathers of urban feral pigeons, both at capture time and after one year of captivity in standardized conditions. Results show that differently coloured pigeons had similar metal concentrations at capture time. Metal concentrations strongly decreased after one year in standardized conditions, and more melanic pigeons had higher concentrations of zinc (but not lead) in their feathers. This suggests that more melanic pigeons have a higher ability to store some metals in their feathers compared with their paler counterparts, which could explain their higher success in urbanized areas. Overall, this work suggests that trace metal pollution may exert new selective forces favouring more melanic phenotypes in polluted environments. PMID:24671830

  1. Evidence for excitation of fluorescence in RPE melanin by multiphoton absorption

    NASA Astrophysics Data System (ADS)

    Glickman, Randolph D.; Rockwell, Benjamin A.; Noojin, Gary D.; Stolarski, David J.; Denton, Michael L.

    2002-06-01

    Previously, we reported that ultrashort, near infrared (NIR) laser pulses caused more DNA breakage in cultured retinal pigment epithelial (RPE) cells than did CW, NIR laser radiation delivering a similar radiant exposure. We hypothesized that this difference was due to multiphoton absorption in an intracellular chromophore such as the RPE melanin. We investigated two-photon excitation of fluorescence in a suspension of isolated bovine RPE melanosomes exposed to a 1-KHz train of approximately 50- fsec laser pulses at 810 nm from a Ti:Sapphire laser, and compared this to the fluorescence excited by CW exposures at 406 nm from a Krypton ion laser. Fluorescence was measured with a PC-based spectrometer. The CW sources excited fluorescence with a peak at 525 nm. The fluorescence intensity depended on the irradiance of the sample, as well as the melanosome concentration. Peak fluorescence was obtained with a suspension of ~2 x 107 melanin granules/ml. The 810-nm, ultrashort pulses also excited fluorescence, but with a broader, lower-amplitude peak. The weaker fluorescence signal excited by the 810-nm ultrashort pulse laser for a given melanosome concentration, compared to 406-nm CW excitation, is possibly due to the smaller two- photon absorption cross-section. These results indicate the involvement of multiphoton absorption in DNA damage.

  2. Photoprotective role of epidermal melanin granules against ultraviolet damage and DNA repair in guinea pig skin

    SciTech Connect

    Ishikawa, T.; Kodama, K.; Matsumoto, J.; Takayama, S.

    1984-11-01

    We previously developed a quantitative autoradiographic technique with special forceps for measuring unscheduled DNA synthesis (UDS) in mouse skin after treatment with ultraviolet light in vivo. By this method, we investigated the relationship between the protective role of melanin and UV-induced DNA repair in black-and-white guinea pigs. Flat areas containing a sharp border between pigmented and unpigmented skin were selected. The skin of the selected areas was shaved and irradiated with short-wave UV (254 nm) or UV-AB (270 to 440 nm, emission peak at 312 nm) at various doses. Immediately after irradiation, the skin was clamped off with forceps, and an isotonic aqueous solution of (methyl-/sup 3/H)thymidine was injected s.c. into the clamped off portion. UDS was clearly demonstrated as silver grains in this portion of the skin after irradiation with 254 nm UV or UV-AB. Errors due to individual differences were avoided by comparing the intensities of UDS in basal cells from pigmented skin and unpigmented skin of the same animals. Unexpectedly, in groups of animals treated with 254 nm UV or UV-AB, no difference in UDS in pigmented and unpigmented skin was seen at any UV dose. These results suggested that epidermal melanin granules do not significantly protect DNA of basal cells against 254 nm UV or UV-AB irradiation. Results of a study on the effect of the wavelength of irradiation on the UDS response of albino guinea pigs are also reported.

  3. Seasonal changes in colour: a comparison of structural, melanin- and carotenoid-based plumage colours.

    PubMed

    Delhey, Kaspar; Burger, Claudia; Fiedler, Wolfgang; Peters, Anne

    2010-07-14

    Plumage coloration is important for bird communication, most notably in sexual signalling. Colour is often considered a good quality indicator, and the expression of exaggerated colours may depend on individual condition during moult. After moult, plumage coloration has been deemed fixed due to the fact that feathers are dead structures. Still, many plumage colours change after moult, although whether this affects signalling has not been sufficiently assessed. We studied changes in coloration after moult in four passerine birds (robin, Erithacus rubecula; blackbird, Turdus merula; blue tit, Cyanistes caeruleus; and great tit, Parus major) displaying various coloration types (melanin-, carotenoid-based and structural). Birds were caught regularly during three years to measure plumage reflectance. We used models of avian colour vision to derive two variables, one describing chromatic and the other achromatic variation over the year that can be compared in magnitude among different colour types. All studied plumage patches but one (yellow breast of the blue tit) showed significant chromatic changes over the year, although these were smaller than for a typical dynamic trait (bill colour). Overall, structural colours showed a reduction in relative reflectance at shorter wavelengths, carotenoid-based colours the opposite pattern, while no general pattern was found for melanin-based colours. Achromatic changes were also common, but there were no consistent patterns of change for the different types of colours. Changes of plumage coloration independent of moult are probably widespread; they should be perceivable by birds and have the potential to affect colour signalling.

  4. The role of fibres and the hypodermis in Compositae melanin secretion.

    PubMed

    De-Paula, Orlando Cavalari; Marzinek, Juliana; Oliveira, Denise Maria Trombert; Machado, Silvia Rodrigues

    2013-01-01

    Melanins are dark, insoluble pigments that are resistant to concentrated acids and bleaching by oxidising agents. Phytomelanin (or phytomelan) is present in the seed coat of some Asparagales and in the fruits of some Compositae. In Compositae fruits, melanin is deposited in the schizogenous spaces between the hypodermis and underlying fibrous layer. Phytomelanin in Compositae is poorly understood, and there are only speculations regarding the cells that produce the pigment and the cellular processes involved in the secretion and polymerisation of phytomelanin. This report describes the cellular processes involved in the secretion of phytomelanin in the pericarp of Praxelis diffusa, a species with a structure typical of the family. The ovaries and fruits at different stages were fixed and processed according to the standard methods of studies of light microscopy and transmission electron microscopy. Hypodermal cells have abundant rough endoplasmic reticulum and mitochondria, and the nuclei have chromatin that is less dense than other cells. These characteristics are typical of cells that synthesise protein/amino acids and suggest no carbohydrate secretion. The fibres, however, have a dense cytoplasm rich in the Golgi bodies that are associated with vesicles and smooth endoplasmic reticulum, common characteristics of carbohydrate secretory cells. Our results indicate that the hypodermal cells are not responsible for the secretion of phytomelanin, as previously described in the literature; in contrast, this function is assigned to the adjacent fibres, which have an organisation typical of cells that secrete carbohydrates.

  5. Melanin Transfer in Human 3D Skin Equivalents Generated Exclusively from Induced Pluripotent Stem Cells.

    PubMed

    Gledhill, Karl; Guo, Zongyou; Umegaki-Arao, Noriko; Higgins, Claire A; Itoh, Munenari; Christiano, Angela M

    2015-01-01

    The current utility of 3D skin equivalents is limited by the fact that existing models fail to recapitulate the cellular complexity of human skin. They often contain few cell types and no appendages, in part because many cells found in the skin are difficult to isolate from intact tissue and cannot be expanded in culture. Induced pluripotent stem cells (iPSCs) present an avenue by which we can overcome this issue due to their ability to be differentiated into multiple cell types in the body and their unlimited growth potential. We previously reported generation of the first human 3D skin equivalents from iPSC-derived fibroblasts and iPSC-derived keratinocytes, demonstrating that iPSCs can provide a foundation for modeling a complex human organ such as skin. Here, we have increased the complexity of this model by including additional iPSC-derived melanocytes. Epidermal melanocytes, which are largely responsible for skin pigmentation, represent the second most numerous cell type found in normal human epidermis and as such represent a logical next addition. We report efficient melanin production from iPSC-derived melanocytes and transfer within an entirely iPSC-derived epidermal-melanin unit and generation of the first functional human 3D skin equivalents made from iPSC-derived fibroblasts, keratinocytes and melanocytes.

  6. Melanin-Based Contrast Agents for Biomedical Optoacoustic Imaging and Theranostic Applications

    PubMed Central

    Longo, Dario Livio; Aime, Silvio

    2017-01-01

    Optoacoustic imaging emerged in early 1990s as a new biomedical imaging technology that generates images by illuminating tissues with short laser pulses and detecting resulting ultrasound waves. This technique takes advantage of the spectroscopic approach to molecular imaging, and delivers high-resolution images in the depth of tissue. Resolution of the optoacoustic imaging is scalable, so that biomedical systems from cellular organelles to large organs can be visualized and, more importantly, characterized based on their optical absorption coefficient, which is proportional to the concentration of absorbing chromophores. Optoacoustic imaging was shown to be useful in both preclinical research using small animal models and in clinical applications. Applications in the field of molecular imaging offer abundant opportunities for the development of highly specific and effective contrast agents for quantitative optoacoustic imaging. Recent efforts are being made in the direction of nontoxic biodegradable contrast agents (such as nanoparticles made of melanin) that are potentially applicable in clinical optoacoustic imaging. In order to increase the efficiency and specificity of contrast agents and probes, they need to be made smart and capable of controlled accumulation in the target cells. This review was written in recognition of the potential breakthroughs in medical optoacoustic imaging that can be enabled by efficient and nontoxic melanin-based optoacoustic contrast agents. PMID:28783106

  7. TRPM1 Forms Ion Channels Associated with Melanin Content in Melanocytes

    PubMed Central

    Oancea, Elena; Vriens, Joris; Brauchi, Sebastian; Jun, Janice; Splawski, Igor; Clapham, David E.

    2014-01-01

    TRPM1(melastatin), which encodes the founding member of the TRPM family of transient receptor potential (TRP) ion channels, was first identified by its reduced expression in a highly metastatic mouse melanoma cell line. Clinically, TRPM1 is used as a predictor of melanoma progression in humans because of its reduced abundance in more aggressive forms of melanoma. Although TRPM1 is found primarily in melanin-producing cells and has the molecular architecture of an ion channel, its function is unknown. Here we describe an endogenous current in primary human neonatal epidermal melanocytes and mouse melanoma cells that was abrogated by expression of microRNA directed against TRPM1. Messenger RNA analysis showed that at least five human ion channel–forming isoforms of TRPM1 could be present in melanocytes, melanoma, brain, and retina. Two of these isoforms are encoded by highly conserved splice variants that are generated by previously uncharacterized exons. Expression of these two splice variants in human melanoma cells generated an ionic current similar to endogenous TRPM1 current. In melanoma cells, TRPM1 is prevalent in highly dynamic intracellular vesicular structures. Plasma membrane TRPM1 currents are small, raising the possibility that their primary function is intracellular, or restricted to specific regions of the plasma membrane. In neonatal human epidermal melanocytes, TRPM1 expression correlates with melanin content. We propose that TRPM1 is an ion channel whose function is critical to normal melanocyte pigmentation and is thus a potential target for pigmentation disorders. PMID:19436059

  8. Spin-label assay for aqueous solutions of transition-metal ions with application to melanin

    NASA Astrophysics Data System (ADS)

    Froncisz, Wojciech; Lai, Ching-san; Hyde, James S.

    The authors and their colleagues have previously developed the spin-label oximetric method in which bimolecular collisions of dissolved O 2 in water with the spin label CTPO [3-carbomoyl-2,2,5,5-tetramethyl-3-pyrroline-1-yloxyl] serve as an assay for [O 2]. This method is, by analogy, here extended to dissolved transition-metal ions with emphasis on Cu(H 2O) 62+, Cu-EDTA, Ni(H 2O) 62+, and Ni-EDTA. Concentrations in the range of 0.05 to 1.0 m M can be determined. Further evidence is supplied that the dominant interaction between CTPO and C 2+ is Heisenberg exchange and that the interaction is of the "strongexchange" type, in agreement with other studies. The method is illustrated by investigation of metal binding to DOPA melanin, which is a model for the biopolymer eumelanin. There is strong discrimination against transition metals that are bound to macromolecules. Melanins are effective ion-exchange resins.

  9. Why do melanin ornaments signal individual quality? Insights from metal element analysis of barn owl feathers.

    PubMed

    Niecke, Manfred; Rothlaender, Sven; Roulin, Alexandre

    2003-09-01

    Melanin-based variation in colour patterns is under strong genetic control and not, or weakly, sensitive to the environment and body condition. Current signalling theory predicts that such traits may not signal honestly phenotypic quality because their production does not entail a significant fitness cost. However, recent studies revealed that in several bird species melanin-based traits covary with phenotypic attributes. In a first move to understand whether such covariat