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Analytical Sciences : the International... Mar 2022This review provides a general understanding of Raman spectroscopy for use in the identification of pigments and dyes. The methodologies associated with a number of... (Review)
Review
This review provides a general understanding of Raman spectroscopy for use in the identification of pigments and dyes. The methodologies associated with a number of different related applications are also summarized. The first part of this review clarifies our basic knowledge regarding natural minerals and pigments. The second part discusses the fundamentals of currently used Raman spectroscopy, including surface-enhanced Raman scattering, μ-Raman spectroscopy, Raman imaging and spatially offset Raman spectroscopy. The third part focuses on recent applications, including the identification and analysis of various pigments and dyes that are used in paintings and related artworks. These studies show that Raman spectroscopy has great potential for use as a method for the rapid, non-destructive identification of such substances.
Topics: Coloring Agents; Pigmentation; Spectrum Analysis, Raman
PubMed: 35359266
DOI: 10.2116/analsci.21SAR03 -
Pigment Cell & Melanoma Research Jul 2021Human skin aging is a natural phenomenon that results from continuous exposure to intrinsic (time, genetic factors, hormones) as well as extrinsic factors (UV exposure,... (Review)
Review
Human skin aging is a natural phenomenon that results from continuous exposure to intrinsic (time, genetic factors, hormones) as well as extrinsic factors (UV exposure, pollution, tobacco). In areas that are frequently exposed to the sun, photoaging blends with the process of intrinsic aging, resulting in an increased senescent cells number and consequently accelerating the aging process. The severity of photodamage depends on constitutional factors, including skin phototype (skin color, tanning capacity), intensity, and duration of sunlight/UV exposure. Aging affects nearly every aspect of cutaneous biology, including pigmentation. Clinically, the phenotype of age pigmented skin has a mottled, uneven color, primarily due to age spots, with or without hypopigmentation. Uneven pigmentation might be attributed to the hyperactivation of melanocytes, altered distribution of pigment, and turnover. In addition to direct damage to pigment-producing cells, photodamage alters the physiological crosstalk between keratinocytes, fibroblasts, endothelial cells, and melanocytes responsible for natural pigmentation homeostasis. Interestingly, age-independent diffuse expression of senescence-associated markers in the dermal and epidermal compartment is also associated with vitiligo, suggesting that premature senescence plays an important role in the pathology.
Topics: Animals; Dermis; Environment; Humans; Hyperpigmentation; Skin Aging; Skin Pigmentation; Stress, Physiological
PubMed: 34048137
DOI: 10.1111/pcmr.12994 -
Journal of Cellular Physiology Dec 2020Eye color is determined as a polymorphism and polygenic trait. Brown is the most common eye color in the world, accounting for about 79%, blue eye color for about... (Review)
Review
Eye color is determined as a polymorphism and polygenic trait. Brown is the most common eye color in the world, accounting for about 79%, blue eye color for about 8-10%, hazel for 5%, and green for 2%. Rare-colored eyes include gray and red/violet. Different factors are involved in determining eye color. The two most important factors are the iris pigment and the way light is scattered from the iris. Gene expression determines the iris pigmentation and how much melanin is present in the eye, which is the number of melanin subunits that identify eye color. The genes involved in the pigmentation of single-nucleotide polymorphism (SNP) have a significant role; and even some genes are included only in the eye color through SNP. MicroRNAs also affect melanocyte synthesis, which is usually affected by the downregulation of essential genes involved in pigmentation. In this study, we assess the biochemical pathways of melanin synthesis, and the role of each gene in this pathway also has been examined in the signaling pathway that stimulates melanin synthesis.
Topics: Color; Eye Color; Humans; Iris; Melanocytes; MicroRNAs; Pigmentation
PubMed: 32488945
DOI: 10.1002/jcp.29824 -
Current Opinion in Genetics &... Aug 2021Recent technical innovations are revealing surprising patterns in mollusc shell pigmentation, such as an unexpectedly modest role for melanins and rapid divergences in... (Review)
Review
Recent technical innovations are revealing surprising patterns in mollusc shell pigmentation, such as an unexpectedly modest role for melanins and rapid divergences in the mix of pigments used to achieve similar colour patterns. The elucidation of the molecular genetic basis of shell pigmentation has been slow, probably because of the high genome complexity of gastropods and bivalves. Recent work within the old field of evolutionary ecology of shell pigmentation allows a greater role for the analysis of large-geographic-scale patterns (sometimes employing citizen-science data), as well as experimental field studies. However, the field remains dominated by land snails as model organisms, while colour pattern evolution in marine gastropods and bivalves, particularly those not exposed to visual predators, remains mysterious.
Topics: Animal Shells; Animals; Biological Evolution; Bivalvia; Color; Ecology; Gastropoda; Phenotype; Pigmentation
PubMed: 33388521
DOI: 10.1016/j.gde.2020.11.009 -
Bioinspiration & Biomimetics May 2018Cephalopods possess unrivaled camouflage and signaling abilities that are enabled by their sophisticated skin, wherein multiple layers contain chromatophore pigment... (Review)
Review
Cephalopods possess unrivaled camouflage and signaling abilities that are enabled by their sophisticated skin, wherein multiple layers contain chromatophore pigment cells (as part of larger chromatophore organs) and different types of reflective cells called iridocytes and leucophores. The optical functionality of these cells (and thus cephalopod skin) critically relies upon subcellular structures partially composed of unusual structural proteins known as reflectins. Herein, we highlight studies that have investigated reflectins as materials within the context of color-changing coatings. We in turn discuss these proteins' multi-faceted properties, associated challenges, and future potential. Through our presentation of selected case studies, we hope to stimulate additional dialogue and spur further research on photonic technologies based on and inspired by reflectins.
Topics: Amino Acid Sequence; Animals; Biological Mimicry; Biomimetic Materials; Biomimetics; Cephalopoda; Chromatophores; Color; Decapodiformes; Optical Phenomena; Pigments, Biological; Proteins; Skin Pigmentation
PubMed: 29799434
DOI: 10.1088/1748-3190/aab804 -
The Journal of Heredity Aug 2021The colorful phenotypes of birds have long provided rich source material for evolutionary biologists. Avian plumage, beaks, skin, and eggs-which exhibit a stunning range... (Review)
Review
The colorful phenotypes of birds have long provided rich source material for evolutionary biologists. Avian plumage, beaks, skin, and eggs-which exhibit a stunning range of cryptic and conspicuous forms-inspired early work on adaptive coloration. More recently, avian color has fueled discoveries on the physiological, developmental, and-increasingly-genetic mechanisms responsible for phenotypic variation. The relative ease with which avian color traits can be quantified has made birds an attractive system for uncovering links between phenotype and genotype. Accordingly, the field of avian coloration genetics is burgeoning. In this review, we highlight recent advances and emerging questions associated with the genetic underpinnings of bird color. We start by describing breakthroughs related to 2 pigment classes: carotenoids that produce red, yellow, and orange in most birds and psittacofulvins that produce similar colors in parrots. We then discuss structural colors, which are produced by the interaction of light with nanoscale materials and greatly extend the plumage palette. Structural color genetics remain understudied-but this paradigm is changing. We next explore how colors that arise from interactions among pigmentary and structural mechanisms may be controlled by genes that are co-expressed or co-regulated. We also identify opportunities to investigate genes mediating within-feather micropatterning and the coloration of bare parts and eggs. We conclude by spotlighting 2 research areas-mechanistic links between color vision and color production, and speciation-that have been invigorated by genetic insights, a trend likely to continue as new genomic approaches are applied to non-model species.
Topics: Animals; Carotenoids; Feathers; Genome; Parrots; Pigmentation
PubMed: 34002228
DOI: 10.1093/jhered/esab015 -
Integrative and Comparative Biology Oct 2021Melanins, the main pigments of the skin and hair in mammals, are synthesized within membrane-bound organelles of melanocytes called melanosomes. Melanosome structure and... (Review)
Review
Melanins, the main pigments of the skin and hair in mammals, are synthesized within membrane-bound organelles of melanocytes called melanosomes. Melanosome structure and function are determined by a cohort of resident transmembrane proteins, many of which are expressed only in pigment cells and localize specifically to melanosomes. Defects in the genes that encode melanosome-specific proteins or components of the machinery required for their transport in and out of melanosomes underlie various forms of ocular or oculocutaneous albinism, characterized by hypopigmentation of the hair, skin, and eyes and by visual impairment. We review major components of melanosomes, including the enzymes that catalyze steps in melanin synthesis from tyrosine precursors, solute transporters that allow these enzymes to function, and structural proteins that underlie melanosome shape and melanin deposition. We then review the molecular mechanisms by which these components are biosynthetically delivered to newly forming melanosomes-many of which are shared by other cell types that generate cell type-specific lysosome-related organelles. We also highlight unanswered questions that need to be addressed by future investigation.
Topics: Animals; Mammals; Melanins; Melanocytes; Melanosomes; Pigmentation
PubMed: 34021746
DOI: 10.1093/icb/icab078 -
JAMA Ophthalmology Dec 2022
Topics: Humans; Iris Diseases; Pigmentation
PubMed: 36301517
DOI: 10.1001/jamaophthalmol.2022.4484 -
Journal of Esthetic and Restorative... Sep 2022To evaluate prevalence, distribution, intensity and extent of physiologic gingival melanin pigmentation (GMP) in black individuals.
OBJECTIVE
To evaluate prevalence, distribution, intensity and extent of physiologic gingival melanin pigmentation (GMP) in black individuals.
MATERIALS AND METHODS
For this cross-sectional study, GMP was evaluated on digital images by three calibrated examiners, according to de Krom (distribution), DOPI (intensity) and Melanin Index (extent) classifications. Descriptive statistics, Wilcoxon, Mann-Whitney, Kruskal-Wallis, Two-way ANOVA, chi square, and K-means cluster analysis were used.
RESULTS
Seventy participants were recruited. The most prevalent GMP categories were: de Krom category 2 (34.3%), DOPI heavy intensity (57.2%), and Melanin index Degree IV (50%). Significant inter-group differences were found for age (p < 0.05) but not gender (p > 0.05). Significant correspondence/overlap was observed between classifications (p > 0.05). Three GMP clusters were identified: Cluster 1 (27%; n = 19) had mild asymmetric and interspersed pigmentation; Cluster 2 (46%; n = 32) had heavy pigmentation in one long continuous ribbon, with pink marginal gingiva; and Cluster 3 (27%; n = 19) had heavy pigmentation in one long continuous ribbon, symmetric, and uniform.
CONCLUSIONS
There may be overlap among GMP classification systems. In black individuals, the predominant GMP presentation is one of a broad zone of heavily pigmented attached gingiva, in a continuous strip from central incisors to canines, symmetrical across the midline, and with pink free marginal gingiva.
CLINICAL RELEVANCE
This is the first study to analyze distribution, intensity, and extent of gingival melanin pigmentation in the same population and to integrate the various classification systems through cluster analysis. The novel findings provide a foundation for patient assessment and counseling and for future studies.
Topics: Cross-Sectional Studies; Gingiva; Gingival Diseases; Humans; Melanins; Pigmentation
PubMed: 34825763
DOI: 10.1111/jerd.12846 -
Plant, Cell & Environment Dec 2023For many fruit crops, the colour of the fruit outwardly defines its eating quality. Fruit pigments provide reproductive advantage for the plant as well as providing... (Review)
Review
For many fruit crops, the colour of the fruit outwardly defines its eating quality. Fruit pigments provide reproductive advantage for the plant as well as providing protection against unfavourable environmental conditions and pathogens. For consumers these colours are considered attractive and provide many of the dietary benefits derived from fruits. In the majority of species, the main pigments are either carotenoids and/or anthocyanins. They are produced in the fruit as part of the ripening process, orchestrated by phytohormones and an ensuing transcriptional cascade, culminating in pigment biosynthesis. Whilst this is a controlled developmental process, the production of pigments is also attuned to environmental conditions such as light quantity and quality, availability of water and ambient temperature. If these factors intensify to stress levels, fruit tissues respond by increasing (or ceasing) pigment production. In many cases, if the stress is not severe, this can have a positive outcome for fruit quality. Here, we focus on the principal environmental factors (light, temperature and water) that can influence fruit colour.
Topics: Fruit; Anthocyanins; Carotenoids; Pigmentation; Water; Gene Expression Regulation, Plant; Plant Proteins
PubMed: 37555620
DOI: 10.1111/pce.14684