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Flake A, Vercruysse K. The Invisible Fraction within Melanin Capable of Absorbing UV Light and with Fluorescent Properties: Is It Lacking Consideration? Int J Mol Sci 2024; 25:8490. [PMID: 39126061 PMCID: PMC11313076 DOI: 10.3390/ijms25158490] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2024] [Revised: 07/28/2024] [Accepted: 07/31/2024] [Indexed: 08/12/2024] Open
Abstract
Expanding on earlier observations, we show that many melanin materials, in vitro synthesized from a wide range of precursors, can be fractionated into a dark-colored precipitate and a near-colorless, dispersible fraction. The dispersible fractions exhibited absorbance in the UVA and UVB range of the electromagnetic spectrum, but none in the visible range. In addition, fluorescent properties were associated with all dispersible fractions obtained. FT-IR spectroscopic analyses were performed to compare both types of fractions. Overall, it appears that some of the properties associated with melanin (UV absorbance, fluorescence) may not necessarily reside in the dark-colored portion of melanin, but in a colorless fraction of the material. It remains to be seen whether any of these in vitro observations have any relevance in vivo. However, we raise the possibility that the presence of a colorless fraction within melanin materials and their associated properties may have received inadequate attention. Given the important association between melanin, UV protection, and skin cancer, it is worthwhile to consider this additional aspect of melanin chemistry.
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Affiliation(s)
| | - Koen Vercruysse
- Chemistry Department, Tennessee State University, Nashville, TN 37209, USA
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Vercruysse KP. The "Unconventional" Effect of Cysteine on the In Vitro Synthesis of Melanin. ACS OMEGA 2024; 9:22794-22800. [PMID: 38826551 PMCID: PMC11137686 DOI: 10.1021/acsomega.4c00889] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/27/2024] [Revised: 04/30/2024] [Accepted: 05/09/2024] [Indexed: 06/04/2024]
Abstract
This report details some of our observations regarding the impact of cysteine on the air-mediated oxidation of catecholamines, particularly epinephrine. The intent was to synthesize light-colored, pheomelanin-like materials. Pheomelanin is commonly described as a material generated from a mixture of catecholamines and cysteine. However, we observed that (1) the presence of cysteine resulted in a concentration-dependent delay in the onset of color formation and (2) the presence of cysteine resulted in darker, more eumelanin-like materials. These effects were particularly impactful in the case of epinephrine. More elaborate studies involving other amino acids or scaled-up reactions were conducted with epinephrine as the precursor. These studies show that other amino acids, e.g., methionine or serine, could lead to darker materials, but none were as impactful as cysteine. Although our results are in contrast to typical descriptions regarding the impact of cysteine on the synthesis of melanin, they may reflect crucial differences between the in vitrovsin vivo synthesis of pheomelanin.
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Affiliation(s)
- Koen P. Vercruysse
- Chemistry Department, Tennessee State University, 3500 John A. Merritt Blvd., Nashville, Tennessee 37209, United States
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Recio P, Rodríguez-Ruiz G, López P, Martín J. Size-related changes and chemical basis of melanin-based body coloration in the amphisbaenian Trogonophis wiegmanni. AMPHIBIA-REPTILIA 2022. [DOI: 10.1163/15685381-bja10109] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Abstract
Melanin is a fundamental pigment in animal coloration as it is involved in many different adaptive functions such as signaling or thermoregulation. Two forms of melanin are known to produce different colors (eumelanin: black; pheomelanin: yellow or brown). Here, we explored whether there were intersexual differences and/or size-related changes in melanization of the amphisbaenian Trogonophis wiegmanni, a fossorial species with a characteristic black and yellow color pattern of scales. We found a clear effect of body length, but not of sex, on the levels of melanization, which was also dependent on the body region; the proportion of melanin-dependent blackish coloration increased with body length in the dorsum, but decreased with body length in the ventral belly area. We also studied the chemical basis of this coloration using Raman spectroscopy and found that eumelanin was present in both black and yellow scales, but pheomelanin was not found in yellow scales, suggesting that this yellow coloration is caused by the reduction of eumelanin or dispersion of melanosomes and/or perhaps by other pigments.
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Affiliation(s)
- Pablo Recio
- Departamento de Ecología Evolutiva, Museo Nacional de Ciencias Naturales, CSIC, José Gutiérrez Abascal 2, E-28006 Madrid, Spain
| | - Gonzalo Rodríguez-Ruiz
- Departamento de Ecología Evolutiva, Museo Nacional de Ciencias Naturales, CSIC, José Gutiérrez Abascal 2, E-28006 Madrid, Spain
| | - Pilar López
- Departamento de Ecología Evolutiva, Museo Nacional de Ciencias Naturales, CSIC, José Gutiérrez Abascal 2, E-28006 Madrid, Spain
| | - José Martín
- Departamento de Ecología Evolutiva, Museo Nacional de Ciencias Naturales, CSIC, José Gutiérrez Abascal 2, E-28006 Madrid, Spain
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Mu X, Liu J, Yuan L, Huang Y, Qian L, Wang C. The pigmentation interference of bisphenol F and bisphenol A. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2020; 266:115139. [PMID: 32663677 DOI: 10.1016/j.envpol.2020.115139] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/15/2019] [Revised: 06/24/2020] [Accepted: 06/27/2020] [Indexed: 06/11/2023]
Abstract
Bisphenol A (BPA) and bisphenol F (BPF) are widely distributed in the environment and daily consumptions, leading to exposure toward human and environmental animals. The potential risk of bisphenol analogs on pigment and skin health is not well documented. In this study, we found that 0.05 mg/L BPF (tolerated daily intake (TDI) value of BPA) affected the particle size and color density of zebrafish melanin. While BPA caused less depigmentation effect toward zebrafish with effective concentration of 5.0 mg/L. The downregulation of melanin synthases induced by BPF is associated with the reduction in melanin. Molecular dynamics indicated that both BPF and BPA could act as ligands of zebrafish and human Tyr family proteins; however, these compounds have completely different energetics and spatial steric effects, potentially explaining their varying depigmentation effects. Additionally, an in vitro assay using A375 melanoma cells demonstrated that the inhibitory effect of BPF on human melanin production was primarily attributed to Tyr inhibition. These findings provide an important basis for understanding the molecular mechanisms of BPF and BPA in melanin inhibition, and the results reflect the skin pigmentation interference risk of these compounds, which are ubiquitous in everyday personal products.
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Affiliation(s)
- Xiyan Mu
- Fishery Resource and Environment Research Center, Chinese Academy of Fishery Sciences, Beijing, People's Republic of China.
| | - Jia Liu
- Fishery Resource and Environment Research Center, Chinese Academy of Fishery Sciences, Beijing, People's Republic of China; College of Sciences, China Agricultural University, Beijing, People's Republic of China
| | - Lilai Yuan
- Fishery Resource and Environment Research Center, Chinese Academy of Fishery Sciences, Beijing, People's Republic of China
| | - Ying Huang
- Fishery Resource and Environment Research Center, Chinese Academy of Fishery Sciences, Beijing, People's Republic of China
| | - Le Qian
- College of Sciences, China Agricultural University, Beijing, People's Republic of China
| | - Chengju Wang
- College of Sciences, China Agricultural University, Beijing, People's Republic of China
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Wu M, Chen X, Cui K, Li H, Jiang Y. Pigmentation formation and expression analysis of tyrosinase in Siniperca chuatsi. FISH PHYSIOLOGY AND BIOCHEMISTRY 2020; 46:1279-1293. [PMID: 32185567 DOI: 10.1007/s10695-020-00788-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/14/2019] [Accepted: 03/04/2020] [Indexed: 06/10/2023]
Abstract
Animal pigmentation primarily depends on the presence and mixing ratio of chromatophores, functioning in animal survival and communication. For the benthic and carnivorous Siniperca chuatsi, pigmentation pattern is key to concealment and predation. In this study, the formation, distribution, and main pattern of chromatophores were observed in the embryos, larvae, skins, and visceral tissues from S. chuatsi. Melanophores were firstly visualized in the yolk sac at segmentation stage, and then they were migrated to the whole body and further clustered into the black stripes, bands, and patches. In adult S. chuatsi, the head, black band, and body side skins mainly contained melanophores, showing as deep or light black. The abdomen skin mainly contained iridophores, showing as silvery. In the eye, the pigment layers were located in the epithelial layers of iris and retina and shown as black. Then, the pigmentation-related gene, tyrosinase gene from S. chuatsi (Sc-tyr) was analyzed by bioinformatics and quantitative methods. The Sc-tyr gene encoded a protein with 540 amino acids (Sc-TYR). The Sc-TYR contained two copper ion binding sites, which were coordinated by six conserved histidines (H182, H205, H214, H366, H370, H393) and necessary for catalytic activity. The Sc-TYR was well conserved compared with TYR of various species with higher degree of sequence similarity with other fishes (77.6-98.3%). The qRT-PCR test showed that the Sc-tyr mRNA reached the peak value at segmentation stage in the embryo development, the black skins displayed a higher expression level than that in silvery skin, and the eye had the highest expression level compared with other tissues. Further research on enzyme activity showed that the expression patterns of tyrosinase activity were similar to that of the Sc-tyr mRNA. Comparing with the results of molecular and phenotype, it was found that the temporal and spatial distributions of tyrosinase corresponded well with changes in pigmentation patterns and the intensity of skin melanization. This study initially explored the pigmentation formation and tyrosinase expression, which served as a foundation for further insight into the genetics mechanism of body color formation in S. chuatsi.
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Affiliation(s)
- Minglin Wu
- Fisheries Research Institute, Anhui Academy of Agricultural Sciences, NO.40 South Nongke Road, Luyang District, Hefei, 230031, Anhui, China
- Anhui Province Key Laboratory of Aquaculture & Stock Enhancement, NO.40 South Nongke Road, Luyang District, Hefei, 230031, Anhui, China
| | - Xiaowu Chen
- National Demonstration Center for Experimental Fisheries Science Education (Shanghai Ocean University), Shanghai, 201306, China
- Shanghai Engineering Research Center of Aquaculture, Shanghai, 201306, China
- Shanghai Collaborative Innovation for Aquatic Animal Genetics and Breeding, Shanghai, 201306, China
| | - Kai Cui
- Fisheries Research Institute, Anhui Academy of Agricultural Sciences, NO.40 South Nongke Road, Luyang District, Hefei, 230031, Anhui, China.
- Anhui Province Key Laboratory of Aquaculture & Stock Enhancement, NO.40 South Nongke Road, Luyang District, Hefei, 230031, Anhui, China.
| | - Haiyang Li
- Fisheries Research Institute, Anhui Academy of Agricultural Sciences, NO.40 South Nongke Road, Luyang District, Hefei, 230031, Anhui, China
- Anhui Province Key Laboratory of Aquaculture & Stock Enhancement, NO.40 South Nongke Road, Luyang District, Hefei, 230031, Anhui, China
| | - Yangyang Jiang
- Fisheries Research Institute, Anhui Academy of Agricultural Sciences, NO.40 South Nongke Road, Luyang District, Hefei, 230031, Anhui, China
- Anhui Province Key Laboratory of Aquaculture & Stock Enhancement, NO.40 South Nongke Road, Luyang District, Hefei, 230031, Anhui, China
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Cao D, Ge Y, Wei Y, Duan H, Gong S. Observations on carapace color change in the juvenile big-headed turtle ( Platysternon megacephalum). PeerJ 2019; 7:e7331. [PMID: 31388471 PMCID: PMC6662560 DOI: 10.7717/peerj.7331] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2018] [Accepted: 06/20/2019] [Indexed: 12/04/2022] Open
Abstract
The carapace color of newborn big-headed turtles (Platysternon megacephalum) is polymorphic and usually consists of two phenotypes: yellowish brown and olive green. As the turtles grew, over the first year of life, its carapace gradually turned from yellowish brown to chestnut brown, or from olive green to dark brown, depending on the phenotype. Meanwhile, the turtle’s plastron remained an orange and black pattern and did not change much. In this study, we primarily used HE staining to observe the carapace color change with age in big-headed turtle juveniles. We took the carapace marginal scute tissues twice from the same turtles before and after the carapace color change. Histological observations show that in the marginal scutes of the four tested turtles with different carapace color phenotypes, melanin granules are all concentrated in the dermal layer underneath the dorsal corneous layer, but rarely on the ventral side. Melanin deposits in the dorsal corneous layer were found to increase as the corneous layers thickened, while the melanin deposits in the ventral corneous layer did not change significantly. However, there was no significant difference in melanin deposition in the epidermis and dermis of the carapace among the yellowish brown, chestnut brown, olive green, and dark brown big-headed turtles. The results of our study indicate that the carapace color darkening in big-headed turtles may not be due to changes in melanin content of the carapace, but is the result of melanin accumulation and superposition in the dorsal corneous layer.
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Chen YM, Su WC, Li C, Shi Y, Chen QX, Zheng J, Tang DL, Chen SM, Wang Q. Anti-melanogenesis of novel kojic acid derivatives in B16F10 cells and zebrafish. Int J Biol Macromol 2019; 123:723-731. [DOI: 10.1016/j.ijbiomac.2018.11.031] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2018] [Revised: 11/06/2018] [Accepted: 11/06/2018] [Indexed: 01/20/2023]
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