Variation In Pigmentation Research Articles

Characterization of photoluminescent and Raman properties of ultramarine blue pigment variants with a novel multimodal approach

Ultramarine Blue (UB) pigment, derived from lapis lazuli, holds a significant place in the history of late medieval and Renaissance Europe, owing to its unusually bright colour and stability. Its prohibitive price, which equalled that of gold, meant that it was only used by estimated artists. In this work we present a non-invasive, multimodal approach to the characterization of the photoluminescent properties of different variants of the pigment. The ultimate goal of this research is to propose a protocol for the identification of UB in artworks thanks to the combination of Raman spectroscopy and time resolved-photoluminescence spectroscopy and imaging.

Analysis of Skin Color Variation using CIELAB Index: An Empirical Study from Delhi, India

Skin color is a conspicuous trait regulated by complex metabolic processes and its significant diversity among Indian populations is quite remarkable making it an ideal choice for dermatological investigation. To elucidate skin pigment variation with respect to age, we studied 714 healthy individuals (aged 20-70 years) using CIELAB system. Skin reflectance was measured from the volar surface of upper arm using DSM II ColorMeter (Cortex Technology, Hadsund, Denmark) among population of Delhi, India to provide CIELAB color space values, L* (light/dark), a* (red/green), and b* (yellow/blue) followed by statistical analysis to examine the correlation between age and gender on skin on constitutive skin pigmentation. The studied parameters were observed to vary widely {L* (Range: 24.98-51.62, M=38.66, SD=4.41), a* (Range: 4.61-17.16, M=10.18, SD=2.03), and b* (Range: 20.16-34.83, M=28.93, SD=2.30)} across all age groups. ANOVA results suggest a statistically significant effect of age on skin lightness {F(4,709)=124.1332, p<0.001}, redness {F(4,709)=20.0594, p<0.001} and yellowness {F(4,709)=95.1434, p<0.001}. Positive correlation was observed between age and both hue (ho) {r(712)=0.9027, p<0.001} and chroma (C) {r(712)=0.9224, p<0.001}. Significant effects of gender were noticed on skin lightness among all age groups, along with skin redness below the age of 40 years (p<0.001). Notable color differences (∆Ε∗ab) were witnessed among males and females across all age groups in the studied population. The age group 21-30 years was found to have the highest ∆Ε∗ab value (3.5987), followed by 51-60 years (2.98), 31-40 years (2.5579), 61-70 years (2.1837), and 41-50 years (1.6639). We would like to highlight that skin lightness, redness, and yellowness differs significantly with age. Females were observed to be lighter in color as compared to males across all age groups. The findings of the current study would provide better understanding of skin color variation among Indian population.

VARIATION OF CHLOROPHYLL AND CAROTENOID PIGMENTS IN SOME WINTER WHEAT FLAG LEAF UNDER DIFFERENT FERTILIZER REGIMES

Five Romanian winter wheat genotypes were analyzed during two experimental years (2019-2020) under four different regime fertilizers for chlorophyll a, chlorophyll b and carotenoid contents from flag leaf, respectively, number of grains/spike, weight of grains/spike, thousand kernel weight. The results showed that the application of additional fertilization increase the analyzed traits, also causing an increase of traits variability. Regarding the variation of photosynthetic pigments from flag leaf as an effect of different fertilizer levels, their concentration is specific to each variety. The highest value of chlorophyll a type is observed in Cezara variety (665.83 mg/kg DW) at N150 kg s.a./ha fertilization level applied in a boot stage. The variation of chlorophyll b concentration in flag leaf is similar to chlorophyll a concentration as a reaction of different nitrogen dose aplication, the highest value for this type of chlorophyll being registered in T. 109-12 at F4 (519.64 mg/kg DW). Carotenoid concentration from flag leaf varies from 3.93 mg/kg DW at Dumitra variety (F3) to 97.63 mg/kg DW at Andrada variety in F2 fertilization level.

MORPHOLOGICAL CHARACTERIZATION OF ROOT INHABITING ENDOPHYTIC BACTERIA

Endophytic bacteria (EBs) are beneficial to stimulating plant growth. However, little information about the EBs associated with soybean plant roots is available. This study examined the diversity of ten EBs isolated from soybean root tissues. Morphological and biochemical characterization methods revealed significant variation among the isolates. Most isolates displayed smooth colony surfaces, regular shapes, and rod-shaped cells. However, Bacterial Strain-5 and 10 exhibited rough surfaces and irregular shapes, while Bacterial Strain-4 displayed round cell shapes instead of the typical rod morphology. Moreover, the isolates demonstrated diverse pigmentation, with strains showing various shades of white, creamy, light yellow, pinkish red, Creamish, yellow, and red. In KOH test, three strains (2, 6, and 9) showed positive reactions to KOH, while the remaining seven strains (1, 3, 4, 5, 7, 8, and 10) showed negative reactions. The catalase test confirmed that four strains (1, 2, 6, and 9) were gram-negative, and the six strains (3, 4, 5, 7, 8 and 10) were gram-positive. In the gram staining test, seven strains (1, 2, 3, 6, 8, 9, and 10) were gram-negative, while the remaining three strains (4, 5, and 7) were gram-positive. Finally, in the starch hydrolysis test, seven strains (1, 2, 3, 6, 8, 9, and 10) were gram-negative, whereas the three strains (4, 5 and 7) were gram-positive. This study will help us identify various EBs that could play a role in the nodule formation and adaptation of soybean plants in diverse soil conditions in Pakistan.

Physiology and biochemistry of naranjilla (Solanum quitoense Lam) fruit during postharvest and the main conservation strategies: A review

Naranjilla (lulo) is an Andean fruit that is very attractive for consumption due to its acid flavor and aroma, as well as its antioxidant, mineral, carbohydrate, and protein content. However, several aspects of the fruit´s pre-harvest and ripening postharvest are unknown, which results in deficiencies during the postharvest handling and conservation. The aim of this review was to present and describe the naranjilla fruit´'s main physiological changes, such as respiration pattern, ethylene production, firmness reduction, and pigment variation, as well as the main preservation technologies implemented during the postharvest period. Naranjilla fruit has been cataloged as a climacteric fruit but its respiratory rate is lower than other fruits in this group. During ripening, there are changes such as a color evolution from green to yellow hue for the pulp and peel, an increase in the concentration of soluble sugars, ascorbic acid, and ethylene production, as well as a reduction in firmness and acidity. Given the nature of its ripening, naranjilla is considered a perishable fruit. To preserve the fruits throughout the postharvest period, different technologies involving cooling, packaging in modified atmospheres (MAP), use of 1-methylciclopropene (1-MCP), UV-C and gamma radiation, and ozone application have been evaluated. From these technologies, refrigeration and MAP are the most often used commercially; they are efficient and relatively economical. More research is required to optimize the use of these technologies for naranjilla preservation.

Enhancing the chemoselective hydrogenation of o-chloronitrobenzene over nanoporous Ni/NiAl3 catalysts

Halogenated aniline, which is usually produced by hydrogenation of halogenated nitrobenzene, is extensively employed in a variety of fields, including insecticides, medicines, pigments, and cosmetics. The design of catalysts to increase their selectivity in this application has become one of the research objectives. Herein, the nanoporous Ni/NiAl3 catalysts with a high specific surface area were designed and prepared by chemical dealloying of NiAl alloy, and the thickness of surface Ni could be easily adjusted. In the hydrogenation of o-chloronitrobenzene (o-CNB) to o-chloroaniline (o-CAN), the catalyst demonstrated great catalytic activity (TOF up to 155 h−1), the TOF is three times that of Raney Ni, and the selectivity to o-CAN remained over 99 % at complete conversion under 50 °C and 2 MPa of H2. The findings demonstrate that at low surface Ni thickness, NiAl3 and Ni have a synergistic effect that alters the electron cloud density of the active site in a way that strengthens the adsorption of intermediates and can successfully modulate selectivity while maintaining high activity. These provide the foundation for designing high selectivity catalysts and preparing nanoporous intermetallic compound catalysts.

Assessing Grain Quality Changes in White and Black Rice under Water Deficit.

Rice is an essential diet component for a significant portion of the population worldwide. Due to the high water demand associated with rice production, improving water use efficiency and grain quality is critical to increasing the sustainability of the crop. This species includes rice varieties with diverse pigmentation patterns. Grain quality, including industrial, nutritional, and functional quality traits, of two black rice genotypes and a commercial white rice cultivar were evaluated in different locations and under different water regimes. Flooding produced higher grain weight compared to alternate wetting and drying irrigation. A high correlation was found between grain color, total phenolic content (TPC), and antioxidant activity. The black rice genotypes showed higher TPC levels and antioxidant capacity, mainly due to higher levels of cyanidin 3-O-glucoside. The phenolic profile varied between whole and polished grains, while mineral composition was influenced by location and irrigation regime. In turn, the environment influenced grain quality in terms of industrial and nutritional characteristics, with significant differences in quality between whole and polished grains. This study provides valuable information on the genotype-environment relationship in rice and its effect on grain quality, which could contribute to selecting genotypes for an appropriate environment.

Melanophilin Polymorphism in Ferrets of Different Color.

In mammals, the main contribution to the variability of pigmentation is made by two groups of genes directly related to the metabolic pathways of pigment synthesis and controlling the transport of melanosomes in melanocytes to keratinocytes. In order to identify the genetic basis of pigmentation variants, the nucleotide sequences of the melanophilin gene were compared in two groups of ferrets-silver-colored and wild-type animals-using sequencing of 16 exons. In carriers of silver color, a single nucleotide deletion was detected in the 9th exon, leading to a shift in the reading frame and the formation of a stop codon downstream. The protein encoded by the mutant allele is almost completely devoid of the C terminal domain of the protein responsible for the contact of melanosomes with actin during their moving to the periphery of melanocytes, but it retains the leading domain involved in the formation of melanosomes. The combination of the preservation of the N domain and the defect of the C domain of the mutant protein for the first time makes it possible to explain the incomplete dominance of the wild-type protein in heterozygotes.

Improving Determination of Pigment Contents in Microalgae Suspension with Absorption Spectroscopy: Light Scattering Effect and Bouguer-Lambert-Beer Law.

The Bouguer-Lambert-Beer (BLB) law serves as the fundamental basis for the spectrophotometric determination of pigment content in microalgae. Although it has been observed that the applicability of the BLB law is compromised by the light scattering effect in microalgae suspensions, in-depth research concerning the relationship between the light scattering effect and the accuracy of spectrophotometric pigment determination remains scarce. We hypothesized that (1) the precision of spectrophotometric pigment content determination using the BLB law would diminish with increasing nonlinearity of absorbance, and (2) employing the modified version of the BLB (mBLB) law would yield superior performance. To assess our hypotheses, we cultivated Phaeodactylum tricornutum under varying illumination conditions and nitrogen supplies in controlled indoor experiments, resulting in suspensions with diverse pigment contents. Subsequently, P. tricornutum samples were diluted into subsamples, and spectral measurements were conducted using different combinations of biomass concentrations and path lengths. This was carried out to assess the applicability of the BLB law and the nonlinearity of absorbance. The chlorophyll a and fucoxanthin contents in the samples were analyzed via high-performance liquid chromatography (HPLC) and subsequently used in our modeling. Our findings confirm our hypotheses, showing that the modified BLB law outperforms the original BLB law in terms of the normalized root mean square error (NRMSE): 6.3% for chlorophyll a and 5.8% for fucoxanthin, compared to 8.5% and 7.9%, respectively.

Variation in pigments in pecan testa during kernel development and storage

The pecan (Carya illinoinensis) is an important tree nut worldwide. Browning of the testa during storage considerably reduces its quality. However, the pigments that cause browning and their accumulation patterns are poorly understood. We analyzed the color changes in the testa during the five developmental stages of the kernel after storage at room temperature to compare differences in their color and identify the pigments. Samples exhibiting different colors along with their corresponding −80 °C storage samples were selected for metabolomic analysis. A total of 591 phenolic compounds were detected, 52 phenolics showed regulatory effects on testa discoloration, and 59 metabolites were identified as possible precursors of the pigments. This study revealed the most thorough phenolic composition of pecan to date. Further, the findings provide new insights into the mechanisms of testa browning, deepens our understanding of the bioactive value of pecans, and contributes to the breeding of less browning-susceptible varieties.

Genetic analysis of pericarp pigmentation variation in Corn Belt dent maize.

The US standard for maize commercially grown for grain specifies that yellow corn can contain at maximum 5% corn of other colors. Inbred parents of commercial hybrids typically have clear pericarp, but transgressive segregants in breeding populations can display variation in pericarp pigmentation. We identified 10 doubled haploid biparental populations segregating for pigmented pericarp and evaluated qualitative genetic models using chi-square tests of observed and expected frequencies. Pigmentation ranged from light to dark brown color, and pigmentation intensity was quantitatively measured across 1,327 inbred lines using hue calculated from RGB pixel values. Genetic mapping was used to identify loci associated with pigmentation intensity. For 9 populations, pigmentation inheritance best fit a hypothesis of a 2- or 3-gene epistatic model. Significant differences in pigment intensity were observed across populations. W606S-derived inbred lines with the darkest pericarp often had clear glumes, suggesting the presence of a novel P1-rw allele, a hypothesis supported by a significant quantitative trait locus peak at P1. A separate quantitative trait locus region on chromosome 2 between 221.64 and 226.66 Mbp was identified in LH82-derived populations, and the peak near p1 was absent. A genome-wide association study using 416 inbred lines from the Wisconsin Diversity panel with full genome resequencing revealed 4 significant associations including the region near P1. This study supports that pericarp pigmentation among dent maize inbreds can arise by transgressive segregation when pigmentation in the parental generation is absent and is partially explained by functional allelic variation at the P1 locus.

Mutations in SLC45A2 lead to loss of melanin in parrot feathers.

Bird plumage coloration is a complex and multifactorial process that involves both genetic and environmental factors. Diverse pigment groups contribute to plumage variation in different birds. In parrots, the predominant green color results from the combination of 2 different primary colors: yellow and blue. Psittacofulvin, a pigment uniquely found in parrots, is responsible for the yellow coloration, while blue is suggested to be the result of light scattering by feather nanostructures and melanin granules. So far, genetic control of melanin-mediated blue coloration has been elusive. In this study, we demonstrated that feather from the yellow mutant rose-ringed parakeet displays loss of melanosome granules in spongy layer of feather barb. Using whole genome sequencing, we found that mutation in SLC45A2, an important solute carrier protein in melanin synthetic pathway, is responsible for the sex-linked yellow phenotype in rose-ringed parakeet. Intriguingly, one of the mutations, P53L found in yellow Psittacula krameri is already reported as P58A/S in the human albinism database, known to be associated with human OCA4. We further showed that mutations in SLC45A2 gene affect melanin production also in other members of Psittaculidae family such as alexandrine and plum-headed parakeets. Additionally, we demonstrate that the mutations associated with the sex-linked yellow phenotype, localized within the transmembrane domains of the SLC45A2 protein, affect the protein localization pattern. This is the first evidence of plumage color variation involving SLC45A2 in parrots and confirmation of associated mutations in the transmembrane domains of the protein that affects its localization.

Growth, yield and metabolite substantiated, eco-physiological evaluation of overcoming accessional and agro-climatic differences in ex-situ raised Valeriana jatamansi Jones. at lower altitude of Sikkim Himalayan region

Valeriana jatamansi Jones. syn. V. wallichi (Family: Caprifoliaceae) is globally known and amongst the 27 listed medicinal plants under National AYUSH Mission (NAM) by National Medicinal Plants Board, New Delhi, Government of India. V. jatamansi is a temperate Himalayan critically vulnerable plant enlisted as plants of conservation concern under Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) Appendix-II with regulated foreign trade. Deplete wild population of V. jatamansi has prioritized conservation via ex-situ raising. The study conducted for V. jatamansi ex-situ raising at Sikkim Himalayan low altitude (tropical hills) region in different potting mix and evaluated for growth, yield and metabolite content substantiated with eco-physiological parameters. The eco-physiological parameters include pigment variations, stability, and the amount of hydroxyvalerenic acid & valerenic acid in below ground quantified using reversed phase-high performance liquid chromatography (RP-HPLC). The study reveals black soil (BS), forest soil (FS), Vermi-compost (VC) and Sand (S) favoured the growth and yield. This is also substantiated by the eco-physiological parameters. The soil nutritional and physical parameters favour higher metabolites hydroxyvalerenic acid and valerenic acid accumulation. The study leads to successful plants raising with increased metabolites. The study paves the way forward, overcoming accessional and agro-climatic differences in growth, yield and metabolite, as appropriately monitored potting media help in consistent & optimized yield and metabolites in V. jatamansi.

Selection and development of superior strains through functional trait-based approach in agarophytic red alga Gracilaria dura (Rhodophyta)

Aim: Gracilaria dura, a red agarophyte, is known for its high-quality agarose content and holds significant potential for commercial applications in aquaculture-related industries. The successful commercial utilization of seaweeds relies heavily on obtaining high-quality seed material with commercially valuable traits. Methodology: This study focuses on employing a functional trait-based approach to develop superior strains of G. dura for commercial aquaculture in India. Cultivation through an open sea farm, variations in growth, agar yield, pigments, antioxidant capacity, and primary productivity among the strains were observed. Results: The daily growth rate ranged from 0.5 to 3.5% per day, while pigment content exhibited variations in the Chlorophyll-a, R-Phycocyanin, and R-Phycoerythrin contents. Antioxidant capacity and gross primary productivity also displayed diverse ranges. From a total of 38 strains of G. dura, three were selected based on their growth and other functional traits, namely ADI0221201, VER0220090, and ADI0221202. Positive correlations were identified between growth and regeneration, as well as growth and Chl-a. Agar content showed a positive association with antioxidant capacity and productivity. 1H NMR analysis identified 12 metabolites as potential biomarkers for G. dura growth. Interpretation: All three selected strains hold promise for future commercial cultivation of Gracilaria dura. Furthermore, six additional strains were selected based on their higher growth and agar yield for targeted breeding and hybridization to enhance desirable traits. Key words: Agarophyte, Aquaculture, Functional traits, Growth, Gracilaria dura, Strain selection

Skin transcriptomic correlates of cave-dwelling Sinocyclocheilus cavefish

IntroductionWith 78 species, Sinocyclocheilus cavefish constitute the largest cavefish radiation in the world. They exhibit remarkable morphological diversity across three habitat types: surface (surface morphs, normal-eyed, variably colored), exclusively-cave-dwelling (stygobitic morphs, eyeless, depigmented), and intermediate between cave and surface (stygophilic morphs, micro-eyed, partially depigmented). Distinctive traits of Sinocyclocheilus include variations in eye and skin conditions associated with their habitat, despite the role of the skin in sensing environmental changes, its habitat correlates are less understood, compared to the well-studied eye conditions.MethodsHere, we analyzed the correlation between Sinocyclocheilus skin morphology and its habitat, utilizing morphological and transcriptomics-based methods. We generated skin RNA-sequencing data for nine species and integrated those with existing data from five additional species. These 14 species represent the primary clades and major habitats of these cavefish.ResultWe identified 7,374 orthologous genes in the skin transcriptome data. Using a comparative transcriptomics approach, 1,348 differentially expressed genes (DEGs) were identified in the three morphotypes. GO and KEGG enrichment analyses suggested that these genes were mainly involved in energy metabolism, immunity and oxidative stress-related functions. Genes related to immune, apoptotic, and necrotic functions were identified through positive selection analysis of orthologous genes. The maximum likelihood phylogenetic tree, based on 1,369, single-copy orthologous genes of the species, was largely concordant with the currently established RAD-seq and mt-DNA based phylogenies. Species with higher cave dependence present lighter coloration, fewer dark blotches, and diminished scale morphology and coverage. We also found that differences in skin gene expression and positive selection effects may have contributed to the degradation of skin color and scales.DiscussionOur study highlights the significance of habitat in shaping skin metabolism, pigmentation variation, and morphology while offering insights into the molecular mechanisms driving these habitat-specific adaptations in Sinocyclocheilus. These findings underscore the transcriptional variation in adapting to diverse environments and contribute to future studies on the evolution and ecology of cavefish.

An allelic series at the EDNRB2 locus controls diverse piebalding patterns in the domestic pigeon.

Variation in pigment patterns within and among vertebrate species reflects underlying changes in cell migration and function that can impact health, reproductive success, and survival. The domestic pigeon (Columba livia) is an exceptional model for understanding the genetic changes that give rise to diverse pigment patterns, as selective breeding has given rise to hundreds of breeds with extensive variation in plumage color and pattern. Here, we map the genetic architecture of a suite of pigmentation phenotypes known as piebalding. Piebalding is characterized by patches of pigmented and non-pigmented feathers, and these plumage patterns are often breed-specific and stable across generations. Using a combination of quantitative trait locus mapping in F2 laboratory crosses and genome-wide association analysis, we identify a locus associated with piebalding across many pigeon breeds. This shared locus harbors a candidate gene, EDNRB2, that is a known regulator of pigment cell migration, proliferation, and survival. We discover multiple distinct haplotypes at the EDNRB2 locus in piebald pigeons, which include a mix of protein-coding, noncoding, and structural variants that are associated with depigmentation in specific plumage regions. These results identify a role for EDNRB2 in pigment patterning in the domestic pigeon, and highlight how repeated selection at a single locus can generate a diverse array of stable and heritable pigment patterns.

Multiomics Analysis Reveals the Chemical and Genetic Bases of Pigmented Potato Tuber.

Anthocyanins and carotenoids determine the diversity of potato tuber flesh pigmentation; here, the underlying chemical and genetic bases were elucidated by multiomics analyses. A total of 31 anthocyanins and 30 carotenoids were quantified in five differently pigmented tubers. Cyanidin and pelargonidin derivatives determined the redness, while malvidin, petunidin, and delphinidin derivatives contributed to purpleness. Violaxanthin derivatives determined the light-yellow color, while zeaxanthin and antheraxanthin derivatives further enhanced the deep-yellow deposition. Integrated transcriptome and proteome analyses identified that F3'5'H highly enhanced anthocyanin biosynthesis in purple flesh and was responsible for metabolic divergence between red and purple samples. BCH2 significantly enhanced carotenoid biosynthesis in yellow samples and along with ZEP, NCED1, and CCD1 genes determined metabolic divergence between light and deep-yellow samples. The weighted correlation network analysis constructed a regulatory network revealing the central role of AN1 in regulating anthocyanin biosynthesis, and 10 new transcription factors related to anthocyanin and carotenoid metabolism regulation were identified. Our findings provide targeted genes controlling tuber pigmentation, which will be meaningful for the genetic manipulation of tuber quality improvement.

Enhancing colorant pigment properties of natural clinoptilolite zeolite through thermal treatment: Comprehensive structural, optical, and colorimetric analysis

This study investigates the transformation of metastable zeolites, specifically clinoptilolite zeolite (CLNP), into amorphous precursors for customized ceramics via ion-exchange and precipitation methods with Co and Zn ions, followed by thermal treatment in the temperature range of 700 ℃ to 1200 ℃. Analytical techniques including TGA/DTA, XRD, FE-SEM, UV-Vis, and Colorimetric analysis reveal that collapse into an amorphous CLNP phase occurs at 750–800 ℃, with subsequent thermal treatments reducing the CLNP phase's weight fraction. Notably, Co-willemite (Zn2−xCoxSiO4) recrystallization occurs at 800–900 ℃ without impurities. Morphological changes, agglomeration, increased particle distribution, and crystallite size growth correlate with rising temperatures. Different pigments emerge, such as brown (700 ℃), green (800 ℃), and blue (900 ℃), with stable Co-willemite persisting post-treatment, yielding high-quality blue pigments. This research highlights the potential for tailored ceramics via zeolite manipulation, offering stable and diverse pigment possibilities in the field.

A gene regulatory network combining Pax3/7, Sox10 and Mitf generates diverse pigment cell types in medaka and zebrafish.

Neural crest cells generate numerous derivatives, including pigment cells, and are a model for studying how fate specification from multipotent progenitors is controlled. In mammals, the core gene regulatory network for melanocytes (their only pigment cell type) contains three transcription factors, Sox10, Pax3 and Mitf, with the latter considered a master regulator of melanocyte development. In teleosts, which have three to four pigment cell types (melanophores, iridophores and xanthophores, plus leucophores e.g. in medaka), gene regulatory networks governing fate specification are poorly understood, although Mitf function is considered conserved. Here, we show that the regulatory relationships between Sox10, Pax3 and Mitf are conserved in zebrafish, but the role for Mitf is more complex than previously emphasized, affecting xanthophore development too. Similarly, medaka Mitf is necessary for melanophore, xanthophore and leucophore formation. Furthermore, expression patterns and mutant phenotypes of pax3 and pax7 suggest that Pax3 and Pax7 act sequentially, activating mitf expression. Pax7 modulates Mitf function, driving co-expressing cells to differentiate as xanthophores and leucophores rather than melanophores. We propose that pigment cell fate specification should be considered to result from the combinatorial activity of Mitf with other transcription factors.

Generation of skin tone and pigmented region-modified images using a pigment discrimination model trained with an optical approach.

Skin tone and pigmented regions, associated with melanin and hemoglobin, are critical indicators of skin condition. While most prior research focuses on pigment analysis, the capability to simulate diverse pigmentation conditions could greatly broaden the range of applications. However, current methodologies have limitations in terms of numerical control and versatility. We introduce a hybrid technique that integrates optical methods with deep learning to produce skin tone and pigmented region-modified images with numerical control. The pigment discrimination model produces melanin, hemoglobin, and shading maps from skin images. The outputs are reconstructed into skin images using a forward problem-solving approach, with model training aimed at minimizing the discrepancy between the reconstructed and input images. By adjusting the melanin and hemoglobin maps, we create pigment-modified images, allowing precise control over changes in melanin and hemoglobin levels. Changes in pigmentation are quantified using the individual typology angle (ITA) for skin tone and melanin and erythema indices for pigmented regions, validating the intended modifications. The pigment discrimination model achieved correlation coefficients with clinical equipment of 0.915 for melanin and 0.931 for hemoglobin. The alterations in the melanin and hemoglobin maps exhibit a proportional correlation with the ITA and pigment indices in both quantitative and qualitative assessments. Additionally, regions overlaying melanin and hemoglobin are demonstrated to verify independent adjustments. The proposed method offers an approach to generate modified images of skin tone and pigmented regions. Potential applications include visualizing alterations for clinical assessments, simulating the effects of skincare products, and generating datasets for deep learning.