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Faisal Almathen, Haitham Elbir, Hussain Bahbahani, Joram Mwacharo, Olivier Hanotte
Pigmentation in mammals is primarily determined by the distribution of eumelanin and pheomelanin, the ratio of which is mostly controlled by the activity of melanocortin 1 receptor (MC1R) and agouti signalling protein (ASIP) genes. Using 91 animals from ten Arabian camel populations, that included the four predominant coat color phenotypes observed in the dromedary (light brown, dark brown, black and white), we investigated the effects of the MC1R and ASIP sequence variants and identified candidate polymorphisms associated with coat color variation...
June 9, 2018: Journal of Heredity
Long Huang, Meiying Liu, Hongye Huang, Yuanqing Wen, Xiaoyong Zhang, Yen Wei
Melanins are well-known biopolymers that are ubiquitous in nature, distributed widely in microorganisms, plants, and animals, and play significant physiological roles. They are mostly biopolymers formed from phenolic compounds by polymerization via quinones. Poly(dopamine) (PDA), a melanin-like material, is similar in structure and properties to eumelanin and has attracted considerable interest for various types of biological applications. This review outlines the recent advances in the structure and synthesis of PDA and discusses applications of PDA in many biological fields, such as biological imaging, photothermal therapy, and drug delivery systems...
May 23, 2018: Biomacromolecules
Ismael Galván, Cuauhtemoc Araujo-Andrade, Mónica Marro, Pablo Loza-Alvarez, Kazumasa Wakamatsu
Eumelanins are large polymers composed of 5,6-dihydroxyindole (DHI) and 5,6-dihydroxyindole-2-carboxylic acid (DHICA). Reactive oxygen species generation is higher during the synthesis of DHI than during the synthesis of DHICA; thus, the production of eumelanins with high relative DHI contents may compromise the viability of cells and organisms. Here, we show that dispersive Raman spectroscopy allows a noninvasive direct detection and quantification of DHI and DHICA in unaltered eumelanins that can be applied to the analysis of natural pigments in biological tissues...
May 8, 2018: Pigment Cell & Melanoma Research
Shanshan Yang, Bo Liu, Kaiyuan Ji, Ruiwen Fan, Changsheng Dong
Mammalian pigmentation requires the production of melanin by melanocytes and its transfer to neighboring keratinocytes. These complex processes are regulated by several molecular pathways. Melanophilin ( MLPH) and WNT family member 1 ( WNT1), known to be involved in melanin transfer and melanin production, respectively, were predicted to be targets of microRNA-5110 using bioinformatics. In the current study, we investigated the effects of microRNA-5110 on pigmentation in alpaca ( Vicugna pacos) melanocytes...
May 7, 2018: FASEB Journal: Official Publication of the Federation of American Societies for Experimental Biology
Rylan Kautz, David D Ordinario, Vivek Tyagi, Priyam Patel, Tam N Nguyen, Alon A Gorodetsky
Cephalopods (e.g., squid, octopuses, and cuttlefish) have long fascinated scientists and the general public alike due to their complex behavioral characteristics and remarkable camouflage abilities. As such, these animals are explored as model systems in neuroscience and represent a well-known commercial resource. Herein, selected literature examples related to the electrical properties of cephalopod-derived biopolymers (eumelanins, chitosans, and reflectins) and to the use of these materials in voltage-gated devices (i...
May 2018: Advanced Materials
María Castejón-Griñán, Cecilia Herraiz, Conchi Olivares, Celia Jiménez-Cervantes, Jose Carlos García-Borrón
The melanocortin 1 receptor gene (MC1R), a well-established melanoma susceptibility gene, regulates the amount and type of melanin pigments formed within epidermal melanocytes. MC1R variants associated with increased melanoma risk promote the production of photosensitizing pheomelanins as opposed to photoprotective eumelanins. Wild-type (WT) MC1R activates DNA repair and antioxidant defenses in a cAMP-dependent fashion. Since melanoma-associated MC1R variants are hypomorphic in cAMP signaling, these non-pigmentary actions are thought to be defective in MC1R-variant human melanoma cells and epidermal melanocytes, consistent with a higher mutation load in MC1R-variant melanomas...
April 6, 2018: Oncogene
Albertus B Mostert, Shermiyah B Rienecker, Christopher Noble, Graeme R Hanson, Paul Meredith
Melanin is the primary photoprotecting pigment in humans as well as being implicated in the development of deadly melanoma. The material also conducts electricity and has thus become a bioelectronic model for proton-to-electron transduction. Central to these phenomena are its spin properties-notably two linked species derived from carbon-centered and semiquinone radicals. Using a novel in situ photoinduced electron paramagnetic resonance technique with simultaneous electrical measurements, we have elucidated for the first time the distinct photoreactivity of the two different radical species...
March 2018: Science Advances
Ming Xiao, Wei Chen, Weiyao Li, Jiuzhou Zhao, You-Lee Hong, Yusuke Nishiyama, Toshikazu Miyoshi, Matthew D Shawkey, Ali Dhinojwala
Eumelanin is one of the most ubiquitous pigments in living organisms and plays an important role in coloration and UV protection. Because eumelanin is highly cross-linked and insoluble in solvents, the chemical structure is still not completely known. In this study, we used atomic force microscopy, X-ray photoelectron spectroscopy and solid-state nuclear magnetic resonance (NMR) to compare intact eumelanosomes (pigment granules mostly made of eumelanin) from four phylogentically distant species: cuttlefish ( Sepia officinalis ) inks, black fish crow ( Corvus ossifragus ) feathers, iridescent wild turkey ( Melleagris gallopavo ) feathers and black human hair...
March 2018: Journal of the Royal Society, Interface
Feifei Yu, Zhenni Pan, Bingliang Qu, Xiangyong Yu, Kaihang Xu, Yuewen Deng, Feilong Liang
Tyrosinase is a key rate-limiting enzyme in melanin synthesis. In this study, a new tyrosinase gene (Tyr) was identified from Pteria penguin and its effect on melanin synthesis was deliberated by RNA interference (RNAi). The cDNA of PpTyr was 1728 bp long, containing a 5'untranslated region (UTR) of 11 bp, a 3'UTR of 295 bp, and an open reading fragment of 1422 bp encoding 473 amino acids. Amino acid alignment showed PpTyr had the highest (50%) identity to tyrosinase-like protein 1 from Pinctada fucata...
May 20, 2018: Gene
Conor L Evans
The natural pigments known as melanins are thought to play a role in the etiology and progression of melanoma, but many of their roles are currently not well understood. While quantification of melanins have, up until now, have been performed in bulk tissue ex vivo, new imaging technologies have unlocked the means to visualize and quantify melanins at the sub-cellular scale. The nonlinear imaging methods known as pump-probe, coherent Raman, and sum-frequency absorption microscopies provide subcellular resolution imaging of melanins, enabling label-free, longitudinal quantification of both eumelanin and pheomelanin in situ and in vivo...
February 27, 2018: Photochemistry and Photobiology
Shosuke Ito, Misa Agata, Kotono Okochi, Kazumasa Wakamatsu
RS-4-(4-hydroxyphenyl)-2-butanol (rhododendrol, RD), a skin-whitening agent, is known to induce leukoderma in some consumers. To explore the mechanism underlying this effect, we previously showed that the oxidation of RD with mushroom or human tyrosinase produces cytotoxic quinone oxidation products and RD-eumelanin exerts a potent pro-oxidant activity. Cellular antioxidants were oxidized by RD-eumelanin with a concomitant production of H2 O2 . In this study, we examined whether this pro-oxidant activity of RD-eumelanin is enhanced by ultraviolet A (UVA) radiation because most RD-induced leukoderma lesions are found in sun-exposed areas...
February 23, 2018: Pigment Cell & Melanoma Research
Shosuke Ito, Kazumasa Wakamatsu
RS -4-(4-hydroxyphenyl)-2-butanol (rhododendrol (RD))-a skin-whitening ingredient-was reported to induce leukoderma in some consumers. We have examined the biochemical basis of the RD-induced leukoderma by elucidating the metabolic fate of RD in the course of tyrosinase-catalyzed oxidation. We found that the oxidation of racemic RD by mushroom tyrosinase rapidly produces RD-quinone, which gives rise to secondary quinone products. Subsequently, we confirmed that human tyrosinase is able to oxidize both enantiomers of RD...
February 12, 2018: International Journal of Molecular Sciences
David M Carr, Ashley A Ellsworth, Gregory L Fisher, Wescley W Valeriano, Juan P Vasco, Paulo S S Guimarães, Rodrigo R de Andrade, Elizabeth R da Silva, Wagner N Rodrigues
The iridescent wings of the Chalcopterix rutilans damselfly (Rambur) (Odonata, Polythoridae) are investigated with focused ion beam/scanning electron microscopy, transmission electron microscopy, and time-of-flight secondary ion mass spectrometry. The electron microscopy images reveal a natural photonic crystal as the source of the varying colors. The photonic crystal has a consistent number and thickness (∼195 nm) of the repeat units on the ventral side of the wing, which is consistent with the red color visible from the bottom side of the wing in all regions...
February 5, 2018: Biointerphases
Tolga N V Karsili, Barbara Marchetti, Spiridoula Matsika
4-Hydroxybenzothiazole (4-HBT) is a molecular constituent of pheomelanin-a polymeric skin centered pigment which acts as a natural photoprotector against harmful solar-UV radiation. Its molecular structure is therefore required to sustain a degree of photostability upon electronic excitation with UV irradiation. Despite its function as a protector against UV, pheomelanin is known to be less photostable than that of its close derivative eumelanin-a dark skin centered pigment. The 4-HBT subunit has long being attributed as a key contributor to the lack of photostability of pheomelanin-a hypothesis which we aim to test in this paper...
March 1, 2018: Journal of Physical Chemistry. A
Junqing Wang, Heng Liu, Yu Liu, Chengchao Chu, Youyuan Yang, Yun Zeng, Weiguo Zhang, Gang Liu
In this work, we report on biodegradable eumelanin-Fe3 O4 hybrid nanoparticles (euMel-Fe3 O4 NPs) for multiple imaging-assisted local photothermolysis. The euMel-Fe3 O4 NPs are rationally prepared via a facile one-step co-precipitation method in the aqueous phase in the presence of eumelanin. The obtained NPs exhibited high stability and aqueous dispersity. euMel-Fe3 O4 NPs could provide T2 -weighted magnetic resonance (MR) and photoacoustic (PA) imaging contrast enhancement prior to the treatment, due to their high r2 relaxivity that was determined to be 245...
February 27, 2018: Biomaterials Science
Raffaella Micillo, Mariagrazia Iacomino, Marco Perfetti, Lucia Panzella, Kenzo Koike, Gerardino D'Errico, Marco d'Ischia, Alessandra Napolitano
To inquire into the role of the carboxyl group as determinant of the properties of 5,6-dihydroxyindole melanins, melanins from aerial oxidation of 5,6-dihydroxyindole-2-carboxylic acid (DHICA) and its DHICA methyl ester (MeDHICA) were comparatively tested for their antioxidant activity. MALDI MS spectrometry analysis of MeDHICA melanin provided evidence for a collection of intact oligomers. EPR analysis showed g-values almost identical and signal amplitudes (ΔB) comparable to those of DHICA melanin, but spin density was one order of magnitude higher, with a different response to pH changes...
January 19, 2018: Pigment Cell & Melanoma Research
David J Carpenter, Mirabelle B Sajisevi, Nikita Chapurin, Clifford Scott Brown, Tracy Cheng, Gregory M Palmer, Daniel S Stevenson, Caroline L Rao, Russell P Hall, Charles R Woodard
OBJECTIVE: Optical spectroscopy offers a noninvasive alternative to biopsy as a first-line screening tool for suspicious skin lesions. This study sought to define several optical parameters across malignant and benign tissue types. STUDY DESIGN: Prospective pilot trial utilizing the Zenalux IM1 optical spectroscopy device from April 2016 to February 2017. For each skin lesion, provider pre-biopsy probability of malignancy was compared to histolopathologic diagnosis...
March 2018: Lasers in Surgery and Medicine
Kouichi Nakagawa, Satoko Minakawa, Daisuke Sawamura, Hideyuki Hara
Continuous wave electron paramagnetic resonance (CW EPR) and X-band (9 GHz) EPR imaging (EPRI) were used to nondestructively investigate the possible differentiation between malignant melanoma (MM) and nevus pigmentosus (NP) melanin radicals in paraffin-embedded specimens. The EPR spectra of both samples were analyzed using linewidth, spectral pattern, and X-band EPRI. The CW-EPR spectra of the MM showed an additional signal overlap. Eumelanin- and pheomelanin-related radicals were observed in the MM specimens...
2017: Analytical Sciences: the International Journal of the Japan Society for Analytical Chemistry
Shoichi Sasamori, Andrew S Wiewel, Vicki A Thomson, Motoko Kobayashi, Katsushi Nakata, Hitoshi Suzuki
The occurrence of black fur, or melanism, in many mammalian species is known to be linked to DNA sequence variation in the agouti signaling protein (Asip) gene, which is a major determinant of eumelanin and pheomelanin pigments in coat color. We investigated 38 agouti (i.e., banded wildtype) and four melanistic Rattus rattus species complex (RrC) lineage II specimens from Okinawa Island, Ryukyu Islands, Japan, for genetic variation in three exons and associated flanking regions in the Asip gene. On Okinawa, a predicted loss-of-function mutation caused by a cysteine to serine amino acid change at p...
December 2017: Zoological Science
Ingrid Ludmilla Rodrigues Cruz, Maria Helena Galdino Figueiredo-Carvalho, Rosely Maria Zancopé-Oliveira, Rodrigo Almeida-Paes
There is a paucity of studies on the cell biology of Sporothrix luriei, the less common of the pathogenic Sporothrix species worldwide. The production of DHN-melanin, eumelanin, and pyomelanin were evaluated on the mycelial and yeast forms of the S. luriei ATCC 18616 strain. The mycelial form of this species produced only pyomelanin, which protected the fungus against environmental stressors such as ultraviolet light, heat, and cold. The yeast form was unable to produce any of the tested melanin types. The lack of melanin in the parasitic form of S...
January 2018: Memórias do Instituto Oswaldo Cruz
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