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International Journal of Molecular... May 2023The melanin pigments eumelanin (EM) and pheomelanin (PM), which are dark brown to black and yellow to reddish-brown, respectively, are widely found among vertebrates.... (Review)
Review
The melanin pigments eumelanin (EM) and pheomelanin (PM), which are dark brown to black and yellow to reddish-brown, respectively, are widely found among vertebrates. They are produced in melanocytes in the epidermis, hair follicles, the choroid, the iris, the inner ear, and other tissues. The diversity of colors in animals is mainly caused by the quantity and quality of their melanin, such as by the ratios of EM versus PM. We have developed micro-analytical methods to simultaneously measure EM and PM and used these to study the biochemical and genetic fundamentals of pigmentation. The photoreactivity of melanin has become a major focus of research because of the postulated relevance of EM and PM for the risk of UVA-induced melanoma. Our biochemical methods have found application in many clinical studies on genetic conditions associated with alterations in pigmentation. Recently, besides chemical degradative methods, other methods have been developed for the characterization of melanin, and these are also discussed here.
Topics: Animals; Melanins; Melanocytes; Pigmentation; Epidermis; Melanoma
PubMed: 37176019
DOI: 10.3390/ijms24098305 -
Philosophical Transactions of the Royal... Jul 2017Humans are a colourful species of primate, with human skin, hair and eye coloration having been influenced by a great variety of evolutionary forces throughout... (Review)
Review
Humans are a colourful species of primate, with human skin, hair and eye coloration having been influenced by a great variety of evolutionary forces throughout prehistory. Functionally naked skin has been the physical interface between the physical environment and the human body for most of the history of the genus , and hence skin coloration has been under intense natural selection. From an original condition of protective, dark, eumelanin-enriched coloration in early tropical-dwelling and , loss of melanin pigmentation occurred under natural selection as dispersed into non-tropical latitudes of Africa and Eurasia. Genes responsible for skin, hair and eye coloration appear to have been affected significantly by population bottlenecks in the course of dispersals. Because specific skin colour phenotypes can be created by different combinations of skin colour-associated genetic markers, loss of genetic variability due to genetic drift appears to have had negligible effects on the highly redundant genetic 'palette' for the skin colour. This does not appear to have been the case for hair and eye coloration, however, and these traits appear to have been more strongly influenced by genetic drift and, possibly, sexual selection.This article is part of the themed issue 'Animal coloration: production, perception, function and application'.
Topics: Animals; Biological Evolution; Eye Color; Hair Color; Human Migration; Humans; Primates; Skin Pigmentation
PubMed: 28533464
DOI: 10.1098/rstb.2016.0349 -
Journal of Translational Medicine Apr 2024Melanocytes are dendritic cells localized in skin, eyes, hair follicles, ears, heart and central nervous system. They are characterized by the presence of melanosomes... (Review)
Review
Melanocytes are dendritic cells localized in skin, eyes, hair follicles, ears, heart and central nervous system. They are characterized by the presence of melanosomes enriched in melanin which are responsible for skin, eye and hair pigmentation. They also have different functions in photoprotection, immunity and sound perception. Melanocyte dysfunction can cause pigmentary disorders, hearing and vision impairments or increased cancer susceptibility. This review focuses on the role of melanocytes in homeostasis and disease, before discussing their potential in regenerative medicine applications, such as for disease modeling, drug testing or therapy development using stem cell technologies, tissue engineering and extracellular vesicles.
Topics: Regenerative Medicine; Melanocytes; Pigmentation; Melanins; Hair Follicle
PubMed: 38589876
DOI: 10.1186/s12967-024-05113-x -
Marine Drugs Sep 2019Haloarchaea are halophilic microorganisms belonging to the archaea domain that inhabit salty environments (mainly soils and water) all over the world. Most of the genera... (Review)
Review
Haloarchaea are halophilic microorganisms belonging to the archaea domain that inhabit salty environments (mainly soils and water) all over the world. Most of the genera included in this group can produce carotenoids at significant concentrations (even wild-type strains). The major carotenoid produced by the cells is bacterioruberin (and its derivatives), which is only produced by this kind of microbes and few bacteria, like . Nevertheless, the understanding of carotenoid metabolism in haloarchaea, its regulation, and the roles of carotenoid derivatives in this group of extreme microorganisms remains mostly unrevealed. Besides, potential biotechnological uses of haloarchaeal pigments are poorly explored. This work summarises what it has been described so far about carotenoids from haloarchaea and their production at mid- and large-scale, paying special attention to the most recent findings on the potential uses of haloarchaeal pigments in biomedicine.
Topics: Animals; Archaea; Bacteria; Biotechnology; Carotenoids; Extreme Environments; Humans; Pigmentation
PubMed: 31500208
DOI: 10.3390/md17090524 -
Poultry Science Aug 2021Eggshell color is an important shell quality trait that influences consumer preference. It is also of particular importance with respect to sexual signaling and the... (Review)
Review
Eggshell color is an important shell quality trait that influences consumer preference. It is also of particular importance with respect to sexual signaling and the physiological and mechanical properties of shell pigment. Pigments include protoporphyrin IX, biliverdin, and traces of biliverdin zinc chelates, with brown eggs being notably rich in protoporphyrin IX, the synthesis of which has a marked effect on the intensity of brown eggshell color. This pigment is initially synthesized in the eggshell gland within the oviduct of laying hens and is subsequently deposited throughout the cuticular and calcareous layers of brown eggshell. In this review, we describe the factors affecting brown eggshell color and potential targets for the regulation of pigment synthesis. Protoporphyrin IX synthesis might be compromised by synthetase-mediated pigment synthesis, the redox status of the female birds, and regulation of the nuclear transcription factors associated with δ-aminolevulinic acid synthetase1. We believe that this review will provide a valuable reference for those engaged in studying eggshell depigmentation.
Topics: Animals; Biliverdine; Chickens; Egg Shell; Female; Ovum; Pigmentation
PubMed: 34214744
DOI: 10.1016/j.psj.2021.101273 -
Heredity Nov 2021Pigmentation divergence between Drosophila species has emerged as a model trait for studying the genetic basis of phenotypic evolution, with genetic changes contributing...
Pigmentation divergence between Drosophila species has emerged as a model trait for studying the genetic basis of phenotypic evolution, with genetic changes contributing to pigmentation differences often mapping to genes in the pigment synthesis pathway and their regulators. These studies of Drosophila pigmentation have tended to focus on pigmentation changes in one body part for a particular pair of species, but changes in pigmentation are often observed in multiple body parts between the same pair of species. The similarities and differences of genetic changes responsible for divergent pigmentation in different body parts of the same species thus remain largely unknown. Here we compare the genetic basis of pigmentation divergence between Drosophila elegans and D. gunungcola in the wing, legs, and thorax. Prior work has shown that regions of the genome containing the pigmentation genes yellow and ebony influence the size of divergent male-specific wing spots between these two species. We find that these same two regions of the genome underlie differences in leg and thorax pigmentation; however, divergent alleles in these regions show differences in allelic dominance and epistasis among the three body parts. These complex patterns of inheritance can be explained by a model of evolution involving tissue-specific changes in the expression of Yellow and Ebony between D. elegans and D. gunungcola.
Topics: Alleles; Animals; Drosophila; Drosophila Proteins; Male; Pigmentation; Species Specificity; Thorax
PubMed: 34537820
DOI: 10.1038/s41437-021-00467-0 -
Current Opinion in Genetics &... Aug 2021Skin pigment patterns of vertebrates are stunningly diverse, and nowhere more so than in teleost fishes. Several species, including relatives of zebrafish, recently... (Review)
Review
Skin pigment patterns of vertebrates are stunningly diverse, and nowhere more so than in teleost fishes. Several species, including relatives of zebrafish, recently evolved cichlid fishes of East Africa, clownfishes, deep sea fishes, and others are providing insights into pigment pattern evolution. This overview describes recent advances in understanding periodic patterns, like stripes and spots, the loss of patterns, and the role of cell-type diversification in generating pigmentation phenotypes. Advances in this area are being facilitated by the application of modern methods of gene editing, genomics, computational analysis, and other approaches to non-traditional model organisms having interesting pigmentary phenotypes. Several topics worthy of future attention are outlined as well.
Topics: Animals; Biological Evolution; Gene Expression Regulation, Developmental; Phenotype; Pigmentation; Skin; Species Specificity; Zebrafish
PubMed: 33743392
DOI: 10.1016/j.gde.2021.02.006 -
Philosophical Transactions of the Royal... Jul 2017Fluorescence is a physico-chemical energy exchange where shorter-wavelength photons are absorbed by a molecule and are re-emitted as longer-wavelength photons. It has... (Review)
Review
Fluorescence is a physico-chemical energy exchange where shorter-wavelength photons are absorbed by a molecule and are re-emitted as longer-wavelength photons. It has been suggested a means of communication in several taxa including flowers, pitcher plants, corals, algae, worms, squid, spiders, stomatopods, fish, reptiles, parrots and humans. The surface or object that the pigment molecule is part of appears to glow due to its setting rather than an actual production of light, and this may enhance both signals and, in some cases, camouflage. This review examines some known uses of fluorescence, mainly in the context of visual communication in animals, the challenge being to distinguish when fluorescence is a functional feature of biological coloration or when it is a by-product of a pigment or other molecule. In general, we conclude that most observations of fluorescence lack enough evidence to suggest they are used in visually driven behaviours.This article is part of the themed issue 'Animal coloration: production, perception, function and application'.
Topics: Animal Communication; Animals; Color; Fluorescence; Invertebrates; Pigmentation; Vertebrates
PubMed: 28533452
DOI: 10.1098/rstb.2016.0335 -
Forensic Science International. Genetics Jan 2021Predicting appearance phenotypes from genotypes is relevant for various areas of human genetic research and applications such as genetic epidemiology, human history,...
Predicting appearance phenotypes from genotypes is relevant for various areas of human genetic research and applications such as genetic epidemiology, human history, anthropology, and particularly in forensics. Many appearance phenotypes, and thus their underlying genotypes, are highly correlated, with pigmentation traits serving as primary examples. However, all available genetic prediction models, including those for pigmentation traits currently used in forensic DNA phenotyping, ignore phenotype correlations. Here, we investigated the impact of appearance phenotype correlations on genetic appearance prediction in the exemplary case of three pigmentation traits. We used data for categorical eye, hair and skin colour as well as 41 DNA markers utilized in the recently established HIrisPlex-S system from 762 individuals with complete phenotype and genotype information. Based on these data, we performed genetic prediction modelling of eye, hair and skin colour via three different strategies, namely the established approach of predicting phenotypes solely based on genotypes while not considering phenotype correlations, and two novel approaches that considered phenotype correlations, either incorporating truly observed correlated phenotypes or DNA-predicted correlated phenotypes in addition to the DNA predictors. We found that using truly observed correlated pigmentation phenotypes as additional predictors increased the DNA-based prediction accuracies for almost all eye, hair and skin colour categories, with the largest increase for intermediate eye colour, brown hair colour, dark to black skin colour, and particularly for dark skin colour. Outcomes of dedicated computer simulations suggest that this prediction accuracy increase is due to the additional genetic information that is implicitly provided by the truly observed correlated pigmentation phenotypes used, yet not covered by the DNA predictors applied. In contrast, considering DNA-predicted correlated pigmentation phenotypes as additional predictors did not improve the performance of the genetic prediction of eye, hair and skin colour, which was in line with the results from our computer simulations. Hence, in practical applications of DNA-based appearance prediction where no phenotype knowledge is available, such as in forensic DNA phenotyping, it is not advised to use DNA-predicted correlated phenotypes as predictors in addition to the DNA predictors. In the very least, this is not recommended for the pigmentation traits and the established pigmentation DNA predictors tested here.
Topics: Computer Simulation; DNA; Eye Color; Female; Forensic Genetics; Genetic Markers; Genotype; Hair Color; Humans; Male; Models, Genetic; Phenotype; Polymorphism, Single Nucleotide; Skin Pigmentation
PubMed: 33070049
DOI: 10.1016/j.fsigen.2020.102395 -
Cell Reports Aug 2023A previously undescribed mechanism underlying butterfly wing coloration patterns was discovered in two distantly related butterfly species, Siproeta stelenes and...
A previously undescribed mechanism underlying butterfly wing coloration patterns was discovered in two distantly related butterfly species, Siproeta stelenes and Philaethria diatonica. These butterflies have bright green wings, but the color pattern is not derived from solid pigments or nanostructures of the scales or from the color of the cuticular membrane but rather from a liquid retained in the wing membrane. Wing structure differs between the green and non-green areas. In the non-green region, the upper and lower cuticular membranes are attached to each other, whereas in the green region, we observed a space of 5-10 μm where green liquid is held and living cells are present. A pigment analysis and tracer experiment revealed that the color of the liquid is derived from hemolymph components, bilin and carotenoid pigments. This discovery broadens our understanding of the diverse ways in which butterfly wings obtain their coloration and patterns.
Topics: Animals; Pigmentation; Butterflies; Wings, Animal; Membranes; Nanostructures
PubMed: 37537843
DOI: 10.1016/j.celrep.2023.112917