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Academic literature on the topic 'MELANIN PIGMENT'

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Published: 11 September 2023

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Journal articles on the topic "MELANIN PIGMENT"

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Youngchim, Sirida, Roderick J. Hay, and Andrew J. Hamilton. "Melanization of Penicillium marneffei in vitro and in vivo." Microbiology 151, no. 1 (January 1, 2005): 291–99. http://dx.doi.org/10.1099/mic.0.27433-0.

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Melanins are found universally in nature and are implicated in the pathogenesis of several important human fungal pathogens. This study investigated whether the conidia and the yeast cells of the thermally dimorphic fungal pathogen Penicillium marneffei produce melanin or melanin-like compounds in vitro and during infection. Treatment of conidia with proteolytic enzymes, denaturant and concentrated hot acid yielded dark particles that were similar in size and shape to the conidia. A melanin-binding monoclonal antibody (mAb) labelled pigmented conidia, yeast cells and the isolated particles as determined by immunofluorescence microscopy. Electron spin resonance spectroscopy revealed that particles derived from pigmented conidia contained a stable free radical compound, consistent with their identification as melanins. Skin tissue from penicilliosis marneffei patients contained yeast cells that were labelled by melanin-binding mAb. Additionally, sera from P. marneffei-infected mice developed a significant antibody response (both IgG and IgM) against melanin. Phenoloxidase activity capable of synthesizing melanin from l-DOPA was detected in cytoplasmic yeast cell extracts. These findings indicate that P. marneffei conidia and yeast cells can produce melanin or melanin-like compounds in vitro and that the yeast cells can synthesize pigment in vivo. Accordingly this pigment may play some role in the virulence of P. marneffei.
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Mokrzynski, Krystian, Shosuke Ito, Kazumasa Wakamatsu, Theodore G. Camenish, Tadeusz Sarna, and Michal Sarna. "Photoreactivity of Hair Melanin from Different Skin Phototypes—Contribution of Melanin Subunits to the Pigments Photoreactive Properties." International Journal of Molecular Sciences 22, no. 9 (April 24, 2021): 4465. http://dx.doi.org/10.3390/ijms22094465.

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Photoreactivity of melanin has become a major focus of research due to the postulated involvement of the pigment in UVA-induced melanoma. However, most of the hitherto studies were carried out using synthetic melanin models. Thus, photoreactivity of natural melanins is yet to be systematically analyzed. Here, we examined the photoreactive properties of natural melanins isolated from hair samples obtained from donors of different skin phototypes (I, II, III, and V). X-band and W-band electron paramagnetic resonance (EPR) spectroscopy was used to examine the paramagnetic properties of the pigments. Alkaline hydrogen peroxide degradation and hydroiodic acid hydrolysis were used to determine the chemical composition of the melanins. EPR oximetry and spin trapping were used to examine the oxygen photoconsumption and photo-induced formation of superoxide anion, and time-resolved near infrared phosphorescence was employed to determine the singlet oxygen photogeneration by the melanins. The efficiency of superoxide and singlet oxygen photogeneration was related to the chemical composition of the studied melanins. Melanins from blond and chestnut hair (phototypes II and III) exhibited highest photoreactivity of all examined pigments. Moreover, melanins of these phototypes showed highest quantum efficiency of singlet oxygen photogeneration at 332 nm and 365 nm supporting the postulate of the pigment contribution in UVA-induced melanoma.
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Nosanchuk, Joshua D., Beatriz L. Gómez, Sirida Youngchim, Soraya Díez, Philip Aisen, Rosely M. Zancopé-Oliveira, Angela Restrepo, Arturo Casadevall, and Andrew J. Hamilton. "Histoplasma capsulatum Synthesizes Melanin-Like Pigments In Vitro and during Mammalian Infection." Infection and Immunity 70, no. 9 (September 2002): 5124–31. http://dx.doi.org/10.1128/iai.70.9.5124-5131.2002.

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ABSTRACT Melanin is made by several important pathogenic fungi and has been implicated in the pathogenesis of a number of fungal infections. This study investigated whether the thermally dimorphic fungal pathogen Histoplasma capsulatum var. capsulatum produced melanin or melanin-like compounds in vitro and during infection. Growth of H. capsulatum mycelia in chemically defined minimal medium produced pigmented conidia. Growth of H. capsulatum yeast in chemically defined minimal medium with l-3,4-dihydroxyphenylalanine (DOPA) or (-)-epinephrine produced pigmented cells. Treatment of the pigmented cells with proteolytic enzymes, denaturant, and hot concentrated acid yielded dark particles that were similar in size and shape to their respective propagules. Melanin-binding monoclonal antibodies (MAb) labeled pigmented conidia, yeast, and the isolated particles as determined by immunofluorescence microscopy. Electron spin resonance spectroscopy revealed that pigmented yeast cells and particles derived from pigmented cells were stable free radicals consistent with their identification as melanins. Tissues from mice infected with H. capsulatum and from biopsy specimens from a patient with histoplasmosis contained fungal cells that were labeled by melanin-binding MAb. Digestion of infected mouse tissues yielded dark particles that reacted with the melanin-binding MAb and were similar in appearance to H. capsulatum yeast cells. Additionally, sera from infected mice contained antibodies that bound melanin particles. Phenoloxidase activity capable of synthesizing melanin from L-DOPA was detected in cytoplasmic yeast cell extracts. These findings indicate that H. capsulatum conidia and yeast 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 to play in the pathogenesis of histoplasmosis.
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Morris-Jones, Rachael, Sirida Youngchim, Beatriz L. Gomez, Phil Aisen, Roderick J. Hay, Joshua D. Nosanchuk, Arturo Casadevall, and Andrew J. Hamilton. "Synthesis of Melanin-Like Pigments by Sporothrix schenckii In Vitro and during Mammalian Infection." Infection and Immunity 71, no. 7 (July 2003): 4026–33. http://dx.doi.org/10.1128/iai.71.7.4026-4033.2003.

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ABSTRACT 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.
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Youngchim, Sirida, Soraya Pornsuwan, Joshua D. Nosanchuk, Wiyada Dankai, and Nongnuch Vanittanakom. "Melanogenesis in dermatophyte species in vitro and during infection." Microbiology 157, no. 8 (August 1, 2011): 2348–56. http://dx.doi.org/10.1099/mic.0.047928-0.

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Dermatophytes are keratinophilic fungi that are the most common cause of fungal skin infections worldwide. Melanin has been isolated from several important human fungal pathogens, and the polymeric pigment is now recognized as an important virulence determinant. This study investigated whether dermatophytes, including Trichophyton rubrum, Trichophyton mentagrophytes, Epidermophyton floccosum and Microsporum gypseum, produce melanin or melanin-like compounds in vitro and during infection. Digestion of the pigmented microconidia and macroconidia of dermatophytes with proteolytic enzymes, denaturant and hot concentrated acid yielded dark particles that retained the size and shape of the original fungal cells. Electron spin resonance spectroscopy revealed that particles derived from pigmented conidia contained a stable free radical signal, consistent with the pigments being a melanin. Immunofluorescence analysis demonstrated reactivity of a melanin-binding mAb with the pigmented conidia and hyphae, as well as the isolate particles. Laccase, an enzyme involved in melanization, was detected in the dermatophytes by an agar plate assay using 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) as the substrate. Skin scrapings from patients with dermatophytoses contained septate hyphae and arthrospores that were reactive with the melanin-binding mAb. These findings indicate that dermatophytes can produce melanin or melanin-like compounds in vitro and during infection. Based on what is known about the function of melanin as a virulence factor of other pathogenic fungi, this pigment may have a similar role in the pathogenesis of dermatophytic diseases.
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Solano, F. "Melanins: Skin Pigments and Much More—Types, Structural Models, Biological Functions, and Formation Routes." New Journal of Science 2014 (March 18, 2014): 1–28. http://dx.doi.org/10.1155/2014/498276.

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This review presents a general view of all types of melanin in all types of organisms. Melanin is frequently considered just an animal cutaneous pigment and is treated separately from similar fungal or bacterial pigments. Similarities concerning the phenol precursors and common patterns in the formation routes are discussed. All melanins are formed in a first enzymatically-controlled phase, generally a phenolase, and a second phase characterized by an uncontrolled polymerization of the oxidized intermediates. In that second phase, quinones derived from phenol oxidation play a crucial role. Concerning functions, all melanins show a common feature, a protective role, but they are not merely photoprotective pigments against UV sunlight. In pathogenic microorganisms, melanization becomes a virulence factor since melanin protects microbial cells from defense mechanisms in the infected host. In turn, some melanins are formed in tissues where sunlight radiation is not a potential threat. Then, their redox, metal chelating, or free radical scavenging properties are more important than light absorption capacity. These pigments sometimes behave as a double-edged sword, and inhibition of melanogenesis is desirable in different cells. Melanin biochemistry is an active field of research from dermatological, biomedical, cosmetical, and microbiological points of view, as well as fruit technology.
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Pralea, Ioana-Ecaterina, Radu-Cristian Moldovan, Alina-Maria Petrache, Maria Ilieș, Simona-Codruța Hegheș, Irina Ielciu, Raul Nicoară, et al. "From Extraction to Advanced Analytical Methods: The Challenges of Melanin Analysis." International Journal of Molecular Sciences 20, no. 16 (August 13, 2019): 3943. http://dx.doi.org/10.3390/ijms20163943.

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The generic term “melanin“ describes a black pigment of biological origin, although some melanins can be brown or even yellow. The pigment is characterized as a heterogenic polymer of phenolic or indolic nature, and the classification of eu-, pheo- and allo- melanin is broadly accepted. This classification is based on the chemical composition of the monomer subunit structure of the pigment. Due to the high heterogeneity of melanins, their analytical characterization can be a challenging task. In the present work, we synthesized the current information about the analytical methods which can be applied in melanin analysis workflow, from extraction and purification to high-throughput methods, such as matrix-assisted laser desorption/ionization mass-spectrometry or pyrolysis gas chromatography. Our thorough comparative evaluation of analytical data published so far on melanin analysis has proven to be a difficult task in terms of finding equivalent results, even when the same matrix was used. Moreover, we emphasize the importance of prior knowledge of melanin types and properties in order to select a valid experimental design using analytical methods that are able to deliver reliable results and draw consistent conclusions.
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Łopusiewicz, Łukasz. "Antioxidant, antibacterial properties and the light barrier assessment of raw and purified melanins isolated from Citrullus lanatus (watermelon) seeds." Herba Polonica 64, no. 2 (June 1, 2018): 25–36. http://dx.doi.org/10.2478/hepo-2018-0008.

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Summary Introduction: The nutritive value and terapeuthic activity of watermelon seeds is known, but up to day no studies on isolation and characterisation of their melanin were conducted. Objective: The aim of the study was to evaluate the antioxidant, antibacterial and light barrier properties of raw and purified melanins isolated from watermelon seeds. Methods: Native melanin was isolated from seeds by alkaline extraction. Obtained pigment was purified by acid hydrolysis. Chemical tests and FT-IR analysis were conducted to determine the melanin nature of the isolated pigments. UV-Vis, transmittance and colour properties were evaluated spectrophotometrically. Antioxidant activity was determined using ABTS and antibacterial activity through a well diffusion method. Results: The results of the study demonstrated that melanins isolated from watermelon seeds had antioxidant, light barrier and antibacterial properties. A purified form of melanin had higher antioxidant activity and light barrier properties than the raw form. Both melanins inhibited the growth of Enterococcus faecalis and Pseudomonas aeruginosa. Conclusions: Watermelon seeds may be considered as a promising source of natural melanin which possess remarkable therapeutic action that can support the traditional use of this plant in the ethnomedicine.
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Sułkowski, Maciej, Marta Kot, Bogna Badyra, Anna Paluszkiewicz, Przemysław M. Płonka, Michał Sarna, Dominika Michalczyk-Wetula, Fabio A. Zucca, Luigi Zecca, and Marcin Majka. "Highly Effective Protocol for Differentiation of Induced Pluripotent Stem Cells (iPS) into Melanin-Producing Cells." International Journal of Molecular Sciences 22, no. 23 (November 26, 2021): 12787. http://dx.doi.org/10.3390/ijms222312787.

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Melanin is a black/brown pigment present in abundance in human skin. Its main function is photo-protection of underlying tissues from harmful UV light. Natural sources of isolated human melanin are limited; thus, in vitro cultures of human cells may be a promising source of human melanin. Here, we present an innovative in vitro differentiation protocol of induced pluripotent stem cells (iPS) into melanin-producing cells, delivering highly pigmented cells in quantity and quality incomparably higher than any other methods previously described. Pigmented cells constitute over 90% of a terminally differentiated population and exhibit features characteristic for melanocytes, i.e., expression of specific markers such as MITF-M (microphthalmia-associated transcription factor isoform M), TRP-1 (tyrosinase-related protein 1), and TYR (tyrosinase) and accumulation of black pigment in organelles closely resembling melanosomes. Black pigment is unambiguously identified as melanin with features corresponding to those of melanin produced by typical melanocytes. The advantage of our method is that it does not require any sophisticated procedures and can be conducted in standard laboratory conditions. Moreover, our protocol is highly reproducible and optimized to generate high-purity melanin-producing cells from iPS cells; thus, it can serve as an unlimited source of human melanin for modeling human skin diseases. We speculate that FGF-8 might play an important role during differentiation processes toward pigmented cells.
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Hellinen, Laura, Sina Bahrpeyma, Anna-Kaisa Rimpelä, Marja Hagström, Mika Reinisalo, and Arto Urtti. "Microscale Thermophoresis as a Screening Tool to Predict Melanin Binding of Drugs." Pharmaceutics 12, no. 6 (June 16, 2020): 554. http://dx.doi.org/10.3390/pharmaceutics12060554.

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Interactions between drugs and melanin pigment may have major impacts on pharmacokinetics. Therefore, melanin binding can modify the efficacy and toxicity of medications in ophthalmic and other disease of pigmented tissues, such as melanoma. As melanin is present in many pigmented tissues in the human body, investigation of pigment binding is relevant in drug discovery and development. Conventionally, melanin binding assays have been performed using an equilibrium binding study followed by chemical analytics, such as LC/MS. This approach is laborious, relatively slow, and limited to facilities with high performance quantitation instrumentation. We present here a screening of melanin binding with label-free microscale thermophoresis (MST) that utilizes the natural autofluorescence of melanin. We determined equilibrium dissociation constants (Kd) of 11 model compounds with melanin nanoparticles. MST categorized the compounds into extreme (chloroquine, penicillin G), high (papaverine, levofloxacin, terazosin), intermediate (timolol, nadolol, quinidine, propranolol), and low melanin binders (atropine, methotrexate, diclofenac) and displayed good correlation with binding parameter values obtained with the conventional binding study and LC/MS analytics. Further, correlation was seen between predicted melanin binding in human retinal pigment epithelium and choroid (RPE-choroid) and Kd values obtained with MST. This method represents a useful and fast approach for classification of compounds regarding melanin binding. Thus, the method can be utilized in various fields, including drug discovery, pharmacokinetics, and toxicology.
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Dissertations / Theses on the topic "MELANIN PIGMENT"

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Coffey, Bethany N. "Melanin as an Oto-Protective Pigment in Two Fish Species: Poecilia Latipinna and Cyprinus Carpio ." TopSCHOLAR®, 2014. http://digitalcommons.wku.edu/theses/1403.

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Melanin is the dark pigment found in most organisms that gives color to the skin, hair, feathers, and eyes of vertebrates. While melanin is known to also be present in the stria vascularis of the mammalian cochlea, its function in the inner ear is still unknown. Some previous studies have indicated that melanin may serve to protect the mammalian ear from hearing loss. Minimal previous research on melanin within the inner ears of fishes has been conducted. In this study, the melanin levels in the inner ears of different color morphs of two fish species (Poecilia latipinna and Cyprinus carpio) were examined, as well as the potential protective role of melanin from acoustical stress. To identify the relationship between fish color morph and inner ear melanin, a spectrophotometric melanin assay was used for dissected inner ears, and transmission electron microscopy (TEM) was used to examine melanosome structure in the crus commune of the inner ears. For each color morph and species, hearing thresholds were quantified before and after sound exposure (150 Hz tone at 165 dB re 1 μPa for 48 h) by measuring auditory evoked potentials (AEPs). Melanin levels were associated with scale color, with black morphs having more inner ear melanin than white or golden morphs. TEM imaging showed that melanosome size varied among color morphs, with black P. latipinna morphs having larger melanosomes than white morphs. Hearing thresholds did not differ significantly among color morphs before sound exposure in either species. However, hearing thresholds post-sound exposure and the associated threshold shifts significantly differed between black morphs and other color morphs in the two species, with black morphs having lower thresholds and exhibiting less hearing loss than the other morphs. This suggests that melanin plays a protective role in the teleost inner ear, similar to what other researchers have found in mammalian models. Teleost fishes may be a new, more efficient model for testing melanin's function in the inner ear and how it interacts with stress from acoustical trauma and ototoxic drugs.
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Glória, Thiago Henrique Ribeiro. "Efeito de α-MSH sobre a expressão gênica de rodopsina, tirosinase e do receptor de α-MSH, subtipo MC1R, em melanócito B16 de Mus musculus." Universidade de São Paulo, 2012. http://www.teses.usp.br/teses/disponiveis/41/41135/tde-08012013-151106/.

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A coloração dos vertebrados deve-se a presença de pigmentos, sintetizados e/ou armazenados em células denominadas células pigmentares cutâneas. A mudança de cor nos vertebrados é principalmente regulada por α-MSH e uma família de enzimas melanossômicas, que incluem tirosinase e as proteínas relacionadas à tirosinase 1 e 2 (TRP-1 e TRP-2, respectivamente). Sua ação está ligada à dispersão dos melanossomos ou síntese de melanina, processos que resultam em escurecimento do animal, enquanto a agregação ou inibição de síntese leva ao seu empalidecimento. Opsinas, como a melanopsina e a rodopsina, além de presentes na retina, podem ser expressas em células pigmentares cutâneas, intermediando foto-respostas de proliferação e de dispersão de melanossomos. O objetivo deste trabalho foi investigar a expressão temporal da rodopsina, tirosinase e do receptor MC1R, bem como os efeitos do tratamento com α-MSH 10-7 M, 10-8 M e 10-9 M por 24 horas sobre esses parâmetros, em melanócitos B16 de Mus musculus, mantidos em escuro constante. Através de PCR em tempo real (quantitativo) demonstrou-se que α-MSH 10-7 M não modula os níveis de mRNA para o receptor MC1R quando comparado com o grupo controle, contudo há uma evidente tendência de redução dos níveis do transcrito. Todavia, na concentração de 10-8 M, observou-se um aumento estatisticamente significativo no nível do transcrito na hora 20 quando comparado ao grupo controle e na concentração de 10-9 M o tratamento mostrou uma diminuição estatisticamente significativa no nível do transcrito entre o grupo controle e o tratado para cada ponto temporal analisado. Para a rodopsina, foi demonstrado que &alpha-MSH 10-7 M modula os níveis do mRNA quando comparado ao grupo controle, mostrando uma diminuição estatisticamente significativa na hora 0 e 16. Na concentração de 10-8 M houve um aumento estatisticamente significativo nos níveis do transcrito na hora 4 quando comparado ao grupo controle. Já, na concentração de 10-9 M, o hormônio induziu um robusto aumento no nível do transcrito quando comparado ao grupo controle para cada ponto temporal analisado. Nossos resultados são pioneiros em demonstrar a modulação de rodopsina por α-MSH, pois não há dados na literatura, seja em retina ou em outros tecidos, que tenham investigado essa ação do hormônio melanotrópico. O mesmo padrão foi observado para a tirosinase, demonstrando uma diminuição estatisticamente significativa na concentração de 10-7 M na hora 0 e um aumento significativo na concentração de 10-8 M na hora 8 e na concentração de 10-9 M na hora 12 e 8. Através de PCR em tempo real (quantitavo) nós demonstramos que α-MSH apresenta uma modulação dose-dependente para o transcrito do mRNA do receptor MC1R, tirosinase e rodopsina, mas não sincronizou a expressão desses genes, que permaneceram arrítmicos
In vertebrates, skin color is given by pigments, synthesized and/or stored in cutaneous pigment cells. The vertebrate color change is mainly regulated by α-MSH and a family of melanosome enzymes, which includes tyrosinase and tyrosinaserelated proteins 1 and 2 (TRP-1 and TRP-2, respectively). α-MSH action is associated with melanosome dispersion or melanin synthesis, processes which lead to skin darkening, whereas melanin aggregation or synthesis inhibition results in skin lightening. Opsins, such as melanopsin and rhodopsin, may be expressed in skin pigment cells, besides being present in the retina, and mediate non visual photoresponses such as cell proliferation and melanosome dispersion. The aim of this study was to investigate the temporal expression of rhodopsin, tyrosinase and the receptor MC1R, as well as the effects of 10-7 M, 10-8 M and 10-9 M α-MSH for 24 hours in Mus musculus B16 melanocytes, kept in constant darkness. Using real time PCR (quantitative) we demonstrated that 10-7 M α-MSH does not modulate MC1R mRNA levels, as compared to the control group, although a tendency to reduction was evident. On the other hand, at the concentration of 10-8 M, we observed a statistically significant increase of the transcript level at the hour 20, as compared to the control group and at the concentration of 10-9 M the treatment showed a statistically significant decrease of the transcript level for each temporal point analyzed. For rhodopsin, we showed that 10-7 M α-MSH modulates mRNA levels, as compared to the control group, demonstrating a statistically significant decrease at the hour 0 and 16. At the concentration of 10-8 M there was a statistically significant increase of transcript levels at the hour 4, as compared to the control group. The hormone at 10-9 M induced a robust increase of the transcript levels, as compared to the control group, for each time point analyzed. Our results are pioneering in demonstrating the regulation of rhodopsin by α-MSH, since there are no data in the literature which report the action of melanotropic hormone on rhodopsin in either the retina or other tissues. Similar pattern was observed for the tyrosinase gene, demonstrating a statistically significant decrease in the concentration of 10-7 M at the hour 0 and a significant increase in the concentration of 10-8 M at the hour 8 and in the concentration of the 10-9 M at the hour 12 and 8. Using real time PCR (quantitative) we demonstrated that α-MSH shows a dose-dependent modulation for mRNA transcripts of the MC1R receptor, tyrosinase and rhodopsin, but the hormone was not able to synchronize the expression of these genes, which remained arhythmic
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Santos, Luciane Rogéria dos. "Expressão gênica de receptor de melatonina (Mel1) e melanopsinas (Opn4x e Opn4m) em melanóforos de Xenopus laevis." Universidade de São Paulo, 2010. http://www.teses.usp.br/teses/disponiveis/41/41135/tde-09022011-104538/.

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Muitos vertebrados ectotérmicos ajustam suas cores corporais para serem confundidos com o ambiente, através da migração de pigmentos no interior de cromatóforos, regulada por sistemas neurais e/ou hormonais. Essas mudanças de coloração auxiliam no mimetismo, termorregulação, comunicação social e expressão de comportamentos como excitação sexual, agressividade e medo. Entretanto, cromatóforos de inúmeras espécies respondem diretamente à luz. Estudos sobre a resposta à luz nos melanóforos de Xenopus laevis levaram à descoberta do fotopigmento melanopsina, uma opsina que está presente na retina de todos os grupos de vertebrados, inclusive no homem. Vários hormônios podem regular o processo de mudança de cor nos vertebrados, dentre eles a melatonina, hormônio secretado pela glândula pineal. Este é o principal órgão responsável pela integração do sistema neuroendócrino dos vertebrados ao meio ambiente, traduzindo direta ou indiretamente a informação do fotoperíodo em sinal hormonal, coordenando assim os ritmos fisiológicos circadianos com o meio ambiente. Os objetivos deste trabalho foram: investigar se a expressão gênica das melanopsinas e do receptor de melatonina em melanóforos de Xenopus laevis apresenta variação temporal sob diferentes condições luminosas; verificar se a expressão gênica das melanopsinas e do receptor de melatonina em melanóforos de Xenopus laevis pode ser modulada por melatonina. Dados do trabalho demonstram que as melanopsinas em melanóforos de Xenopus laevis são sincronizadas aos ciclos de claro-escuro, expressando um robusto ritmo ultradiano com período de 16h para Opn4m e um ritmo circadiano com período de 25h para Opn4x. Curiosamente, essa ritmicidade só foi observada quando os melanóforos foram mantidos em ciclos 12C:12E e foram submetidos à troca de meio durante a fase clara do fotoperíodo. A constância na expressão gênica do receptor de melatonina Mel1, quer sob diferentes regimes de luz, quer sob tratamento por melatonina, sugere que esse gene é extremamente estável, não sofrendo alterações ao ser submetido a estímulos exógenos, podendo ser considerado um gene constitutivo. O tratamento com melatonina por 6h na fase clara do fotoperíodo, além de inibir drasticamente a expressão de Opn4x e Opn4m, aboliu a ritimicidade de ambas as melanopsinas. Nossos resultados indicam que os melanóforos de Xenopus laevis possuem um relógio funcional e podem ser caracterizados como relógios periféricos, porém necessitam do ciclo claro-escuro associado à troca de meio para exibirem sua sincronização.
Many ectothermic vertebrates adjust their body color to mimic the environment, through the pigment migration within chromatophores, regulated by neural and / or hormonal systems. These changes in color help in camouflage, thermoregulation, social communication and behaviors such as sexual arousal, agressiveness and fear. However, chromatophores of several species respond directly to light. Studies about light response in melanophores of Xenopus laevis have led to the discovery of the photopigment melanopsin, an opsin that is present in the retina of all vertebrate groups, including man. Various hormones may regulate the process of color change in vertebrates, among them melatonin, hormone secreted by the pineal gland. This is the main organ responsible for the integration of the neuroendocrine system of vertebrates to the environment, translating directly or indirectly the photoperiod information into hormonal signal, thus coordinating physiological circadian rhythms with the environment. The objectives of this work were: to investigate whether the gene expression of melanopsins and melatonin receptor in melanophores of Xenopus laevis exhibited temporal variation under different light conditions; to verify whether gene expression of melanopsins and melatonin receptor in melanophores of Xenopus laevis could be modulated by melatonin. Our data show that melanopsins in melanophores of Xenopus laevis are synchronized to light-dark cycles, expressing a robust ultradian rhythm with a period of 16h for Opn4m and circadian rhythm with a period of 25h for Opn4x. Interestingly, the rhythm was only observed when the melanophores were maintained in 12L: 12D regime and medium change was performed during the fotophase of photoperiod. The constancy in the expression of melatonin receptor Mel1c, either under different light regimes, or under treatment by melatonin, suggesting that this gene is extremely stable, not being altered by exogenous stimulus, and may be considered a constitutive gene. Treatment with melatonin for 6h during the fotophase of the photoperiod, drastically inhibit the expression of Opn4x and Opn4m, and abolished the rhythm of both melanopsins. Our results indicate that melanophores of Xenopus laevis possess a functional clock and can be characterized as peripheral clocks, but they need the light-dark cycle associated with change of medium to exhibit their synchronization.
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Wang, Erpei. "Pigments in Rust Fungi: Biosynthesis, Role in Plant-Pathogen Interactions, and Evolution." Thesis, The University of Sydney, 2018. http://hdl.handle.net/2123/18434.

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Diseases caused by rust fungi represent critical constraints to global plant production. A characteristic feature of these pathogens is the striking pigments they produce in one or more spore forms, which give them a rusty appearance. These pigments are thought to protect rust fungi against UV radiation and oxidative stress, and possibly act as virulence factors. The cytoplasmic carotenoid pigment composition and relative abundance of 14 rust species were studied, including Puccinia graminis f. sp. tritici (Pgt), P. striiformis f. sp. tritici, P. triticina, P. hordei, P. psidii, P. thaliae, P. oxalidis, Uromyces viciae-fabae, and Phragmidium rubi-idaei, along with colour mutants of several rust species with white, chocolate, pale yellow, dark brown, black, grey, yellow, yellow-orange, dark red and orange urediniospores. Four carotenoids had been found in rust fungi: phytoene, lycopene, -carotene and -carotene. The carotenoid composition did not vary much within rust species but, Among the 14 species investigated, the ratios of -/-carotene varied from 0.14 to 4.49, which might be used as an additional taxonomic character in rust fungi. Candidate genes for carotenoid biosynthesis in Pgt were identified, cloned and functionally complemented using specifically engineered strains of Escherichia coli. The carotenoid biosynthesis pathway in rust fungi was elucidated, with only two genes, CrtYB and CrtI, catalysing the reactions from GGPP to -carotene. Our understanding of carotenoid pigmentation evolution in rust fungi was improved by phylogenetic analysis. Both CrtYB and CrtI are closely related among rust fungi, other pathogenic fungi, and some aphids. A blackish-brown pigment was extracted from the wall of wild-type Pgt urediniospores. The spectrophotometric analysis results suggested that the spore wall pigment extracted from urediniospores of Pgt resembled the DOPA type melanin. Plausible structures of the fragments from this pigment were tentatively proposed.
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Teh, Muy-Teck. "Cellular and molecular studies on pigment-granule translocation in Xenopus laevis melanophores." Thesis, King's College London (University of London), 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.312268.

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Hsiung, Bor-Kai. "COLOR PRODUCTION MECHANISMS IN SPIDERS AND THEIR BIOMIMICRY POTENTIAL." University of Akron / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=akron1497355826810282.

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SUFI, BIANCA da S. "Utilização de cocultura de melanócitos e queratinócitos para avaliação da ação do líquido da castanha de caju (LCC) na pigmentação epidérmica." reponame:Repositório Institucional do IPEN, 2013. http://repositorio.ipen.br:8080/xmlui/handle/123456789/10197.

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Gonçalves, Rita de Cássia Ribeiro [UNESP]. "Estudo da estrutura e da atividade biológica do pigmento melanina produzido pelo fungo Aspergillus nidulans." Universidade Estadual Paulista (UNESP), 2008. http://hdl.handle.net/11449/100739.

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Do fungo Aspergillus nidulans foi isolado um mutante que apresenta producao aumentada do pigmento melanina. Este pigmento, formado pela polimerizacao oxidativa de compostos fenolicos e/ou indolicos, pode estar presente na parede celular ou no meio de cultura. Embora nao seja essencial para o crescimento dos fungos, a melanizacao parece aumentar a capacidade de sobrevivencia das especies em condicoes desfavoraveis, fornecendo protecao contra radiacao UV, altas temperaturas, enzimas hidroliticas, metais pesados e agentes oxidantes. A obtencao deste pigmento, na forma pura, tem despertado interesse biotecnologico devido a sua utilizacao em formulacoes cosmeticas, principalmente pela sua propriedade fotoprotetora e antioxidante. Tendo em vista o potencial farmacologico do pigmento melanina, este trabalho tem como objetivos fazer a caracterizacao estrutural e funcional do pigmento extraido do fungo A. nidulans. Os resultados de espectrometria de massas indicam que a estrutura da melanina do fungo A. nidulans e composta de duas grandes unidades, representadas pelos fragmentos de massas moleculares igual a 573 e 550, com grupamentos diidroxindol e aneis pirrolicos substituidos. Os ensaios de citotoxicidade mostram que a melanina extraida do fungo A. nidulans nao causa danos significativos aos componentes celulares, tanto antes como pos metabolizacao. Os ensaios de mutagenicidade sugerem que a melanina nao apresenta propriedades mutagenicas para as linhagens TA 97a, TA 98, TA 100 e TA 102 de Salmonella thyphimurium. No teste antimicrobiano, observase que a melanina do fungo nao apresenta potencial como antibacteriano frente a Staphylococcus aureus, Escherichia coli e Enterococcus faecalis, quando comparadas com as substancias de referencia, ampicilina e cloranfenicol. Quanto...
A mutant that presents increased production of the melanin pigment was isolated from the Aspergillus nidulans fungus. This pigment, formed by the oxidative polymerization of phenolic and/or indolic compounds, can be present in the cellular wall or culture medium. Although it is not essential for the fungal growth, melanization seems to increase the survival capacity of the species in unfavorable conditions, supplying protections against UV radiation, high temperatures, hydrolytic enzymes, heavy metals and oxidants agents. The attainment of this pigment, in its pure form, has taken biotechnological interest due to its use in cosmetic formulations, mainly for its photoprotector and antioxidant property .Considering the pharmacological potential of the melanin pigment, this study aims to make the structural and functional characterization of the pigment extracted from A. nidulans fungus. The results of mass spectrometry indicate that the melanin structure of the A. nidulans fungus is composed of two large units, represented by the fragments of molecular mass equal to 573 and 550, with dihydroxyindole groups and substituted pyrrolic rings. The cytotoxicity assays have shown that the melanin extracted from the A. nidulans fungus does not cause significant damages to the cellular components, before and after metabolization. The mutagenicity assays suggest that the melanin does not present mutagenic properties for the strains TA 97a, TA 98, TA 100 and TA 102 of Salmonella thyphimurium. In the antimicrobial test, it is observed that the fungal melanin does not present antibacterial potential facing Staphylococcus aureus, Enterococcus faecalis and Escherichia coli, when compared to the reference substances, ampicilin and cloranphenicol. Regarding the immunomodulatory activity, it was verified that the melanin does not stimulate NO release... (Complete abstract click electronic access below)
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9

Walsh, Neil. "Investigation into the genetic basis of carotenoid and melanin colouration in red-billed queleas." Thesis, University of Cambridge, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.609827.

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Gonçalves, Rita de Cássia Ribeiro. "Estudo da estrutura e da atividade biológica do pigmento melanina produzido pelo fungo Aspergillus nidulans /." Araraquara : [s.n.], 2008. http://hdl.handle.net/11449/100739.

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Orientador: Sandra Regina Pombeiro Sponchiado
Banca: Iracilda Zeppone Carlos
Banca: Valdecir Farias Ximenes
Banca: Jairo Kenupp Bastos
Dagmar Ruth Stach Machado
Resumo: Do fungo Aspergillus nidulans foi isolado um mutante que apresenta producao aumentada do pigmento melanina. Este pigmento, formado pela polimerizacao oxidativa de compostos fenolicos e/ou indolicos, pode estar presente na parede celular ou no meio de cultura. Embora nao seja essencial para o crescimento dos fungos, a melanizacao parece aumentar a capacidade de sobrevivencia das especies em condicoes desfavoraveis, fornecendo protecao contra radiacao UV, altas temperaturas, enzimas hidroliticas, metais pesados e agentes oxidantes. A obtencao deste pigmento, na forma pura, tem despertado interesse biotecnologico devido a sua utilizacao em formulacoes cosmeticas, principalmente pela sua propriedade fotoprotetora e antioxidante. Tendo em vista o potencial farmacologico do pigmento melanina, este trabalho tem como objetivos fazer a caracterizacao estrutural e funcional do pigmento extraido do fungo A. nidulans. Os resultados de espectrometria de massas indicam que a estrutura da melanina do fungo A. nidulans e composta de duas grandes unidades, representadas pelos fragmentos de massas moleculares igual a 573 e 550, com grupamentos diidroxindol e aneis pirrolicos substituidos. Os ensaios de citotoxicidade mostram que a melanina extraida do fungo A. nidulans nao causa danos significativos aos componentes celulares, tanto antes como pos metabolizacao. Os ensaios de mutagenicidade sugerem que a melanina nao apresenta propriedades mutagenicas para as linhagens TA 97a, TA 98, TA 100 e TA 102 de Salmonella thyphimurium. No teste antimicrobiano, observase que a melanina do fungo nao apresenta potencial como antibacteriano frente a Staphylococcus aureus, Escherichia coli e Enterococcus faecalis, quando comparadas com as substancias de referencia, ampicilina e cloranfenicol. Quanto... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: A mutant that presents increased production of the melanin pigment was isolated from the Aspergillus nidulans fungus. This pigment, formed by the oxidative polymerization of phenolic and/or indolic compounds, can be present in the cellular wall or culture medium. Although it is not essential for the fungal growth, melanization seems to increase the survival capacity of the species in unfavorable conditions, supplying protections against UV radiation, high temperatures, hydrolytic enzymes, heavy metals and oxidants agents. The attainment of this pigment, in its pure form, has taken biotechnological interest due to its use in cosmetic formulations, mainly for its photoprotector and antioxidant property .Considering the pharmacological potential of the melanin pigment, this study aims to make the structural and functional characterization of the pigment extracted from A. nidulans fungus. The results of mass spectrometry indicate that the melanin structure of the A. nidulans fungus is composed of two large units, represented by the fragments of molecular mass equal to 573 and 550, with dihydroxyindole groups and substituted pyrrolic rings. The cytotoxicity assays have shown that the melanin extracted from the A. nidulans fungus does not cause significant damages to the cellular components, before and after metabolization. The mutagenicity assays suggest that the melanin does not present mutagenic properties for the strains TA 97a, TA 98, TA 100 and TA 102 of Salmonella thyphimurium. In the antimicrobial test, it is observed that the fungal melanin does not present antibacterial potential facing Staphylococcus aureus, Enterococcus faecalis and Escherichia coli, when compared to the reference substances, ampicilin and cloranphenicol. Regarding the immunomodulatory activity, it was verified that the melanin does not stimulate NO release... (Complete abstract click electronic access below)
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Books on the topic "MELANIN PIGMENT"

1

Riley, P. A., and Jan Borovansky. Melanins and melanosomes: Biosynthesis, biogenesis, physiological, and pathological functions. Weinheim: Wiley-Blackwell, 2011.

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Ma, Xiao-Peng, and Xiao-Xiao Sun. Melanin: Biosynthesis, functions and health effects. Hauppauge, N.Y: Nova Science, 2011.

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International, Pigment Cell Conference (13th 1986 Tucson Ariz ). Advances in pigment cell research: Proceedings of symposia and lectures from the Thirteenth International Pigment Cell Conference held in Tucson, Arizona, October 5-9, 1986. New York: Liss, 1988.

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Jeanfils, Joseph. Pigments et biosphère: Les couleurs de la vie. Paris: Vuibert, 2008.

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1929-, Bagnara Joseph T., ed. Biological, molecular, and clinical aspects of pigmentation: Proceedings of the XIIth International Pigment Cell Conference, Giessen, Federal Republic of Germany. [Tokyo, Japan]: University of Tokyo Press, 1985.

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Mark, Elwood J., ed. Melanoma and naevi: Incidence, interrelationships, and implications. Basel: Karger, 1988.

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Friede, Charles Robison. Diffusion Study of Dopa Melanin Pigment. Creative Media Partners, LLC, 2021.

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Armstrong, Bruce K., Claire M. Vajdic, and Anne E. Cust. Melanoma. Oxford University Press, 2017. http://dx.doi.org/10.1093/oso/9780190238667.003.0057.

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Melanoma is a cancer of melanocytes, cells that produce the brown-black skin pigment melanin. Melanocytes originate in cells of the neural crest and migrate during embryogenesis, principally to the epidermis, eyes, and some mucous membranes (mouth, nose, esophagus, anus, genitourinary organs, and conjunctiva). Cutaneous melanoma afflicts mainly fair-skinned people of European origin, among whom sun exposure is the major cause. Five-year relative survival can exceed 90%. Invasive cutaneous melanoma in US whites occurs mostly on the trunk (34%), and upper limbs and shoulders (26%). Melanoma incidence rates have been increasing predominantly in European-origin populations. Ultraviolet (UV) radiation, from the sun or artificial tanning devices, probably both initiates and promotes melanoma. Nevi are markers of increased melanoma risk and direct precursors in some cases; nevus-prone people may require only modest sun exposure to initiate melanoma. Other risk factors include family history and sun sensitivity.
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Powell, Jenny. Normal skin function. Edited by Patrick Davey and David Sprigings. Oxford University Press, 2018. http://dx.doi.org/10.1093/med/9780199568741.003.0243.

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In simplest terms, our skin is a layer that separates and protects us from the external environment. This assumes the skin is a passive covering to keep the insides safe and the outside out, and overlooks its enormous complexity. The skin is our largest organ and is constantly regenerating, but how efficiently it does so depends on a number of factors, some known, others unknown. It is an efficient mechanical barrier (designed for wear and repair), and a complex immunological membrane. It has a generous vascular, lymphatic, and nervous supply, all covering a considerable area. It has specialist structural and functional properties relating to specific areas, but also specialist cells within the layers of the skin. Most importantly, skin is the organ of display, an important part of social and sexual behaviour, immediately accessible to all, and often regarded as a barometer of the general state of health. Permanent scars inflicted on the skin may be a cause of great distress to the patient. Skin consists of a superficial layer, ‘the epidermis’ (concerned with producing protective keratin and a pigment called melanin), which adheres closely to the deeper layer, ‘the dermis’ (which provides the strength of the skin and houses the appendages), via the basement membrane. Loose connective tissue and fat underlie the dermis.
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Gawkrodger, David J. Disorders of pigmentation. Edited by Patrick Davey and David Sprigings. Oxford University Press, 2018. http://dx.doi.org/10.1093/med/9780199568741.003.0258.

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Skin colour is due to a mixture of the pigments melanin, oxyhaemoglobin (in blood), and carotene (in the stratum corneum and subcutaneous fat). Pigmentary diseases are common and particularly distressing to those with darker skin. Disorders of pigmentation often involve melanocytes. Vitiligo is the commonest disease of reduced pigmentation, and melasma is the commonest of hyperpigmentation.
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Book chapters on the topic "MELANIN PIGMENT"

1

Menke, Henk E. "Pigment Disorders and Pigment Manipulations." In The Melanin Millennium, 183–205. Dordrecht: Springer Netherlands, 2012. http://dx.doi.org/10.1007/978-94-007-4608-4_12.

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Arnheiter, Heinz, and Julien Debbache. "Development of Melanin-Bearing Pigment Cells in Birds and Mammals." In Pigments, Pigment Cells and Pigment Patterns, 185–208. Singapore: Springer Singapore, 2021. http://dx.doi.org/10.1007/978-981-16-1490-3_6.

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Gupta, Puja, Madangchanok Imchen, and Ranjith Kumavath. "Exploration and Characterization of Melanin Pigment Produced by Actinomycetes." In Methods in Actinobacteriology, 671–81. New York, NY: Springer US, 2022. http://dx.doi.org/10.1007/978-1-0716-1728-1_99.

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Chelliah, Ramachandran, and Deog-Hwan Oh. "Screening of Microbes for the Production of Pigment (Melanin)." In Methods in Actinobacteriology, 667–69. New York, NY: Springer US, 2022. http://dx.doi.org/10.1007/978-1-0716-1728-1_98.

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Srivastava, Jyoti, Joyabrata Mal, Manju Verma, and Rupika Sinha. "Mini-review on Inhibitors of Human Tyrosinase." In Proceedings of the Conference BioSangam 2022: Emerging Trends in Biotechnology (BIOSANGAM 2022), 96–105. Dordrecht: Atlantis Press International BV, 2022. http://dx.doi.org/10.2991/978-94-6463-020-6_10.

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AbstractMelanin is a major pigment of human skin that protects the skin from harmful ultraviolet radiation, DNA damage and oxidative stress. However, the excess accumulation of melanin may lead to various hyperpigmentation-related diseases. Tyrosinase is a copper containing enzyme that regulates the rate-limiting step of melanin synthesis. So, inhibiting tyrosinase is the crucial target for researchers for the treatment of hyperpigmentation. Unfortunately, almost all the literature is based on mushroom tyrosinase (mTYR) for their application on humans as pure human tyrosinase (hTYR) is difficult to isolate. Since presently used tyrosinase inhibitors are developed using mushroom tyrosinase, they are insufficient to match the affinity, selectivity and efficacy required to target the human tyrosinase. Therefore, there is an urgent need for identifying a selective tyrosinase inhibitor that matches the selectivity and safety standards of human tyrosinase. This mini-review is focused on the tyrosinase inhibitors developed and evaluated using human tyrosinase.
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Wakamatsu, Kazumasa, and Shosuke Ito. "Melanins in Vertebrates." In Pigments, Pigment Cells and Pigment Patterns, 45–89. Singapore: Springer Singapore, 2021. http://dx.doi.org/10.1007/978-981-16-1490-3_2.

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Farthmann, B., S. Schmitz, K. Krasagakis, and C. E. Orfanos. "Photoprotection by Total Melanin Content and Pigment Phenotype (Eumelanin, Pheomelanin) in Human Melanoma Cell Lines." In Skin Cancer and UV Radiation, 181–85. Berlin, Heidelberg: Springer Berlin Heidelberg, 1997. http://dx.doi.org/10.1007/978-3-642-60771-4_21.

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Taylor, Adam M., and Koen P. Vercruysse. "Analysis of Melanin-like Pigment Synthesized from Homogentisic Acid, with or without Tyrosine, and Its Implications in Alkaptonuria." In JIMD Reports, 79–85. Berlin, Heidelberg: Springer Berlin Heidelberg, 2016. http://dx.doi.org/10.1007/8904_2016_27.

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Roberts, N. B., S. A. Curtis, A. M. Milan, and L. R. Ranganath. "The Pigment in Alkaptonuria Relationship to Melanin and Other Coloured Substances: A Review of Metabolism, Composition and Chemical Analysis." In JIMD Reports, 51–66. Berlin, Heidelberg: Springer Berlin Heidelberg, 2015. http://dx.doi.org/10.1007/8904_2015_453.

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Belozerskaya, Tatiana A., Natalya N. Gessler, and Andrey A. Aver‘yanov. "Melanin Pigments of Fungi." In Fungal Metabolites, 263–91. Cham: Springer International Publishing, 2017. http://dx.doi.org/10.1007/978-3-319-25001-4_29.

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Conference papers on the topic "MELANIN PIGMENT"

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Lin, Tai-Yuan David, Woraphong Manuskiatti, Christine Dierickx, William A. Farinelli, Marney Fisher, Thomas Flotte, Howard Baden, and R. Rox Anderson. "Influence of Hair Growth Cycle on Hair Follicle Destruction by Pulsed Ruby Laser Treatment in Newborn Mice." In Lasers in Dermatology: Bio-Optics and Treatment of Human Skin. Washington, D.C.: Optica Publishing Group, 1997. http://dx.doi.org/10.1364/lid.1997.sac5.

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It has been shown that using normal mode ruby laser pulses (694 nm) is an effective method of selectively destroying brown or black pigmented hair follicles in adult Caucasians (Grossman et al, 1996). The pigment, melanin, contained within the dark hair follicles acts as a target for light absorption when exposed to a well characterized range of wavelengths (Anderson and Parrish, 1981). Based on principles of selective photothermolysis, exposure to carefully chosen wavelength and pulse duration characteristics result in preferential absorption by the target pigment and sufficient heating to cause localized cellular destruction (Anderson and Parrish, 1983).
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Miura, Masahiro, Shuichi Makita, Shinnosuke Azuma, Yoshiaki Yasuno, Toshihiro Mino, Tatsuo Yamaguchi, Satoshi Sugiyama, and Takuya Iwasaki. "Retinal pigment epithelium-melanin specific contrast imaging by multi-contrast OCT." In Ophthalmic Technologies XXX, edited by Fabrice Manns, Per G. Söderberg, and Arthur Ho. SPIE, 2020. http://dx.doi.org/10.1117/12.2542922.

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Kilbride, Paul E., Kathleen M. Pori, and Kenneth R. Alexander. "Human ocular melanin assessed by imaging fundus reflectometry." In OSA Annual Meeting. Washington, D.C.: Optica Publishing Group, 1988. http://dx.doi.org/10.1364/oam.1988.wy4.

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Because of the possible role of melanin in various ocular pathologies, it is important to develop a noninvasive objective measurement of this ocular pigment. We have used imaging fundus reflectometry to assess the spatial distribution of melanin within the macular region. A microchannel plate-intensifier solid-state video camera viewed an area of the fundus (21° horizontally by 16° vertically) through the optics of a modified Zeiss fundus camera. A fiber-optic lightguide illuminated by a computer-controlled optical system replaced the normal Zeiss light source. Images of the unbleached and bleached fundus were obtained at thirteen wavelengths (460-700 nm). For the present study, digitally processed images of the bleached fundus obtained at long wavelengths (>620 nm) were used to provide an estimate of the spatial distribution of melanin in the macular region. In three Caucasian subjects, our measurements show a region of lower reflectance in these long wavelengths that is ~10° in diameter and centered on the fovea. This result is consistent with previous anatomic studies reporting that the melanin optical density is higher in the central macula than in the surrounding region.
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Shu, Xiao, Hao F. Zhang, and Wenzhong Liu. "Applying photoacoustics to quantification of melanin concentration in retinal pigment epithelium (Conference Presentation)." In Photons Plus Ultrasound: Imaging and Sensing 2016, edited by Alexander A. Oraevsky and Lihong V. Wang. SPIE, 2016. http://dx.doi.org/10.1117/12.2213840.

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Pask, H. M., and J. A. Piper. "0.9Watt 580nm solid-state laser source." In The European Conference on Lasers and Electro-Optics. Washington, D.C.: Optica Publishing Group, 1998. http://dx.doi.org/10.1364/cleo_europe.1998.cwj3.

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Laser sources producing output in the yellow spectral region are of interest for a variety of display, remote-sensing and medical applications, including the removal of vascular lesions, for which the main requirement for the laser is strong absorption by haemoglobin, with minimal absorption by the melanin pigment in tissue. Average powers of about 0.5 to 1W are required at 580nm+/-5nm, and a high repetition-rate source is beneficial in reducing thermal damage to the surrounding tissue. A solid-state laser source would offer an attractive alternative to the laser sources currently used for these procedures, which include pulsed dye, krypton ion and copper vapour lasers.
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Harper, Danielle J., Thomas Konegger, Kornelia Schützenberger, Marco Augustin, Martin Glösmann, Antonia Lichtenegger, Pablo Eugui, Christoph K. Hitzenberger, and Bernhard Baumann. "Hyperspectral optical coherence tomography: a tool for in vivo visualization of melanin in the retinal pigment epithelium." In Optical Coherence Imaging Techniques and Imaging in Scattering Media, edited by Stephen A. Boppart, Maciej Wojtkowski, and Wang-Yuhl Oh. SPIE, 2019. http://dx.doi.org/10.1117/12.2526059.

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7

Meleppat, Ratheesh K., and Robert J. Zawadzki. "Directional optical coherence tomography: a novel method to detect the changes in melanin pigmentation of the retinal pigment epithelium." In Ophthalmic Technologies XXXII, edited by Daniel X. Hammer, Karen M. Joos, and Daniel V. Palanker. SPIE, 2022. http://dx.doi.org/10.1117/12.2610289.

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8

"Study of melanin and anthocyanin biosynthesis regulation in barley grain by transcriptomic analysis of near-isogenic lines with different pigment composition." In Plant Genetics, Genomics, Bioinformatics, and Biotechnology. Novosibirsk ICG SB RAS 2021, 2021. http://dx.doi.org/10.18699/plantgen2021-215.

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9

Delori, François C. "Noninvasive measurement of ocular pigments by reflectometry and fluorophotometry." In OSA Annual Meeting. Washington, D.C.: Optica Publishing Group, 1990. http://dx.doi.org/10.1364/oam.1990.md1.

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Optical methods for diagnosing and treating ocular disease are affected both by the scattering characteristics of tissues in the stratified layers of the fundus (retina, choroid, and sclera) and by the absorption of light by ocular pigments. Both reflectance and fluorescence methods for studying these pigments (melanin, hemoglobin, lipofuscin, macular, and visual pigments) have relied on numerous optical simplifications. Optical models1,2 have been introduced to aid understanding of the overall optical characteristics of the fundus layers and to characterize the amount of melanin and hemoglobin in the choroid.
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Rodzkin, A. S., T. S. Erchinskaya, and N. V. Ikonnikova. "BIOCHEMICAL CHARACTERISTICS OF THE COMPONENT COMPOSITION OF FRUIT BODIES OF MEDICINAL BASIDIOMYCETES." In SAKHAROV READINGS 2021: ENVIRONMENTAL PROBLEMS OF THE XXI CENTURY. International Sakharov Environmental Institute of Belarusian State University, 2021. http://dx.doi.org/10.46646/sakh-2021-2-96-99.

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The content of the main biochemical components: protein, polysaccharides, lipids, melanin pigments, and phenolic compounds was studied in the fruit bodies of strains of fungi of the genera Ganoderma, Inonotus, Phallus, and Pleurotus. The amount of total and true protein was 14.6-28.0% and 10.9-18.5%, respectively, polysaccharides-10.8-28.4%, lipids-3.1-3.5%, phenolic compounds-580-2200 mg%. Higher protein content was observed in the strains of the fungus P. ostreatus, polysaccharides - in the strains of G. lucidum and Ph. impudicus, phenolic compounds in the strains of the fungus I. obliquus. The largest amount of polysaccharides (22.0-24.0 %) was isolated from the fruit bodies of G. lucidum (reishi). The leader in the content of polysaccharides in the dry biomass of fruit bodies is the fungus Phallus impudicus (common Veselka). The fruit bodies of Chaga I. obliquus (strains KI 5, KI 7) and Veselka Ph. impudicus (strains PI 2, PI 5, and PI 9) contained significant amounts of melanin pigments - 10.3-13.8% and 7.1-7.4%, respectively.
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Reports on the topic "MELANIN PIGMENT"

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Jones, Robert M., Alison K. Thurston, Robyn A. Barbato, and Eftihia V. Barnes. Evaluating the Conductive Properties of Melanin-Producing Fungus, Curvularia lunata, after Copper Doping. Engineer Research and Development Center (U.S.), November 2020. http://dx.doi.org/10.21079/11681/38641.

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Abstract:
Melanins are pigmented biomacromolecules found throughout all domains of life. Of melanins’ many unique properties, their malleable electrically conductive properties and their ability to chelate could allow them to serve as material for bioelectronics. Studies have shown that sheets or pellets of melanin conduct low levels of electricity; however, electrical conductance of melanin within a cellular context has not been thoroughly investigated. In addition, given the chelating properties of melanin, it is possible that introducing traditionally con-ductive metal ions could improve the conductivity. Therefore, this study investigated the conductive properties of melanized cells and how metal ions change these. We measured the con-ductivity of pulverized Curvularia lunata, a melanized filamentous fungi, with and without the addition of copper ions. We then com-pared the conductivity measurements of the fungus to chemically synthesized, commercially bought melanin. Our data showed that the conductivity of the melanized fungal biomass was an order of magnitude higher when grown in the presence of copper. However, it was two orders of magnitude less than that of synthetic melanin. Interestingly, conductance was measurable despite additional constituents in the pellet that may inhibit conductivity. Therefore, these data show promising results for using melanized cells to carry electrical signals.
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