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Aposematic organisms rely on their conspicuous appearance to signal that they are defended and unpalatable. Such phenotypes are strongly tied to survival and reproduction. Aposematic colors and patterns are highly variable; however, the genetic, biochemical, and physiological mechanisms producing this conspicuous coloration remain largely unidentified. Here, we identify genes potentially affecting color variation in two color morphs of Ranitomeya imitator: the orange-banded Sauce and the redheaded Varadero morphs. We examine gene expression in black and orange skin patches from the Sauce morph and black and red skin patches from the Varadero morph. We identified genes differentially expressed between skin patches, including those that are involved in melanin synthesis (e.g. mlana, pmel, tyrp1), iridophore development (e.g. paics, ppat, ak1), pteridine synthesis (e.g. gch1, pax3-a, xdh), and carotenoid metabolism (e.g. dgat2, rbp1, scarb2). In addition, using weighted correlation network analysis, we identified the top 50 genes with high connectivity from the most significant network associated with gene expression differences between color morphs. Of these 50 genes, 13 were known to be related to color production (gch1, gmps, gpr143, impdh1, mc1r, pax3-a, pax7, ppat, rab27a, rlbp1, tfec, trpm1, xdh).

Clearance of comedone is challenging in the treatment of acne, as it is very likely to develop into inflammatory lesions. However, there is lack of effective treatments for dense comedones. Comedone extractor has been widely employed by dermatologists, but the effect is temporary and may cause irritation. CO2 laser is a potential method for dense comedones, but the efficacy and safety need to be explored. In this single-center, randomized, single-blind, self-controlled study, the faces of patients with dense comedones were randomly assigned into two sides receiving either ultra-pulse dynamic CO2 laser or comedone extraction at an interval of 2 weeks for 4 sessions. After 4 treatments, the average comedone reduction rate of the CO2 laser was 64.49%, which was higher than that by the extractor (46.36%) (P <.001). 79.16% of the patients reached over 50% reduction by CO2 laser, while only 37.5% on extractor treated side reached 50% clearance. Texture index, porphyrin index, red zone, erythema index, and transepidermal water loss decreased after both treatments, and CO2 laser showed more improvement. There was no difference in hydration index and melanin index between the two treatments. No permanent or severe side effects were observed on both sides. The CO2 laser showed higher comedone clearance with lower pain scores than the comedone extractor. [ABSTRACT FROM AUTHOR]

Background Aim Patients and Methods Results Conclusion Clinical Trial Registration The picosecond 755‐nm alexandrite laser and topical tranexamic acid (TA) have shown promise in treating melasma.This aim of this study was to evaluate the efficacy and safety of combining to a picosecond 755‐nm alexandrite laser combined with topical TA for melasma treatment.Forty‐eight patients’ facial halves with bilateral symmetrical melasma were randomized to receive either topical TA and picosecond laser treatment or laser monotherapy. All patients received three consecutive picosecond laser treatment sessions at 4‐week intervals, and additional one side facial received topical TA treatment twice daily until 4 weeks after the third treatments. Efficacy was assessed using the Modified Melasma Area and Severity Index (mMASI) score, VISIA (Canfield, USA) red area feature counts, and average pore volume as measured by Antera 3D®. Patient satisfaction was evaluated through questionnaires.Thirty‐five patients completed the study. Post‐treatment, mMASI scores and VISIA red area feature counts were lower in combination therapy halves and laser monotherapy halves, and average melanin level was lower in the combination therapy halves (p < 0.05). Comparisons between the combination therapy halves and laser monotherapy halves after the third treatment revealed significant differences in mMASI scores, melanin levels, and VISIA red area feature counts (p < 0.05). After treatment, patient satisfaction rates in the combination therapy halves and monotherapy halves was 71.4% and 54.3%, respectively (p < 0.05). No obvious adverse effects were observed in the combination therapy halves; whereas, 10.42% (5/48) of participants in the laser monotherapy halves experienced temporary pigmentation, which resolved within 3 months.The picosecond 755‐nm alexandrite laser, when used independently and in combination with topical TA, has been proven to be effective in the improvement of melasma. However, the combined treatment approach showed a more pronounced improvement in melasma symptoms, with higher patient satisfaction, and was associated with a lower incidence of adverse effects. These findings strongly support that integrating topical TA with picosecond laser therapy as a superior therapeutic strategy for melasma management.Chinese Clinical Trial Registry: ChiCTR2200057771. [ABSTRACT FROM AUTHOR]

Melanoma is the most aggressive type of skin cancer, with few therapeutic alternatives following metastasis development. In recent years, drug delivery-associated nanotechnology has shown promising targeted results with diminished adverse effects compared to conventional treatments. This study aimed to (1) examine the effects of plant-derived α-arbutin, a natural compound and (2) compare these findings with bioactively developed liposomes containing α-arbutin utilizing the B16-F10 murine melanoma cell line as a model. Liposomes were obtained through reversed-phase evaporation by applying a spray dryer to assess their stability. The following biologic assays were measured cytotoxicity/antiproliferative (MTT, Neutral Red, and dsDNA PicoGreen). In addition, the levels of melanin and purinergic enzymes were also measured. The production of reactive oxygen species (ROS) and nitric oxide (NO) was determined as a measure of oxidative state. Treatment with nano-liposome containing alpha-arbutin induced a significant 68.4% cytotoxicity, similar to the positive control, in the B16-F10 murine melanoma cell line at 72 hr. Further, arbutin and liposomes containing alpha-arbutin increased levels of ROS and nitrite formation at 72 hr at the highest concentration (100 and 300 µg/ml) of treatments. Arbutin and liposomes containing alpha-arbutin reduced melanin levels at all tested concentrations. In addition, arbutin and alpha-arbutin containing liposomes lowered nucleotides (AMP, ADP, and ATP) and nucleoside (adenosine) levels in melanoma cells. Evidence suggests that α-arbutin containing liposome can be considered as an alternative immunosuppressive agent stimulated in melanoma treatment. [ABSTRACT FROM AUTHOR]

This study aimed to examine the structural alterations of the deep gray matter (DGM) in the basal ganglia circuitry of Parkinson's disease (PD) patients with freezing of gait (FOG) using quantitative susceptibility mapping (QSM) and neuromelanin-sensitive magnetic resonance imaging (NM-MRI). Twenty-five (25) PD patients with FOG (PD-FOG), 22 PD patients without FOG (PD-nFOG), and 30 age- and sex-matched healthy controls (HCs) underwent 3-dimensional multi-echo gradient recalled echo and NM-MRI scanning. The mean volume and susceptibility of the DGM on QSM data and the relative contrast (NM RC-SNpc) and volume (NM volume-SNpc) of the substantia nigra pars compacta on NM-MRI were analyzed among groups. A multiple linear regression analysis was performed to explore the associations of FOG severity with MRI measurements and disease stage. The PD-FOG group showed higher susceptibility in the bilateral caudal substantia nigra (SN) compared to the HC group. Both the PD-FOG and PD-nFOG groups showed lower volumes than the HC group in the bilateral caudate and putamen as determined from the QSM data. The NM volume-SNpc on NM-MRI in the PD-FOG group was significantly lower than in the HC and PD-nFOG groups. Both the PD-FOG and PD-nFOG groups showed significantly decreased NM RC-SNpc. The PD-FOG patients showed abnormal neostriatum atrophy, increases in iron deposition in the SN, and lower NM volume-SNpc. The structural alterations of the DGM in the basal ganglia circuits could lead to the abnormal output of the basal ganglia circuit to trigger the FOG in PD patients. [ABSTRACT FROM AUTHOR]

Background: In vitro single‐cell experiments may yield inconsistent results compared to clinical trials. To enhance the reliability of cosmetic active ingredient screening, a coculture model of B16F10‐HaCaT cells was established in vitro based on the structural characteristics of human skin, thereby improving the credibility of experimental outcomes. Currently, most cosmetic whitening additives primarily target simple efficacy goals such as inhibiting tyrosinase activity or melanin transfer. Therefore, investigating novel and efficient whitening additives has become a prominent research focus. Objectives: The aim is to establish an in vitro cell coculture model for more reliable experimental results and investigate the mechanism by which Paeonia lactiflora Pall seeds oil inhibits melanin production and transfer. Methods: The impact of different concentrations of Paeonia lactiflora Pall seeds oil on cocultured cell proliferation rate was assessed using cck8 assay. Tyrosinase inhibition ability in cocultured cells was tested using levodopa as a substrate. Melanin production inhibition ability in coculture cells was evaluated by lysing cells with sodium hydroxide. The effect of Paeonia lactiflora Pall seeds oil on dendrite‐related gene expression levels was examined through qPCR analysis. Additionally, Western blotting was employed to study the effect of Paeonia lactiflora Pall seeds oil on dendrite‐related protein expression levels. Results: Different concentrations of Paeonia lactiflora Pall seeds oil did not affect the proliferation activity of cocultured cells. A specific concentration of α‐MSH increased cell tyrosinase activity, cellular melanin content, as well as Rac1, Cdc42, and PAR‐2 gene and protein expression related to dendritic formation. Treatment with a certain concentration of Paeonia lactiflora Pall seeds oil resulted in decreased tyrosinase activity and melanin content in cells along with downregulated expression levels of Rac1, Cdc42, and PAR‐2 genes and proteins associated with dendritic formation. Conclusions: Paeonia lactiflora Pall seeds oil at specific concentrations exhibits the ability to inhibit tyrosinase activity, decrease melanin content, and possesses the potential to impede melanin transfer. [ABSTRACT FROM AUTHOR]

ABSTRACT Photobiomodulation (PBM) using 830 nm light‐emitting diode (LED) benefits tissue regeneration, wound healing and neural stimulation. However, there is not much exploration of its effect on melanocytes and ex vivo skin model. This study aims to investigate the mechanism behind the anti‐melanogenic activity of 830 nm LED and provides evidence for its activity in human ex vivo skin model. Our results showed that 830 nm LED at fluences ranging from 5 to 20 J/cm2 inhibited melanosome maturation and reduced melanin content, tyrosinase activity and melanogenesis‐related proteins. 830 nm LED inhibited the phosphorylation of AKT and its downstream FOXO3a, leading to nuclear translocation of FOXO3a. Furthermore, FOXO3a knockdown and AKT activator like SC79 could reverse the melanogenesis inhibition phenotype induced by 830 nm LED. In human ex vivo skin model, Fontana–Masson staining revealed a decrease in epidermal basal pigmentation after 830 nm LED irradiation. Taken together, 830 nm LED demonstrated the anti‐melanogenic activity via FOXO3a. [ABSTRACT FROM AUTHOR]

Pyomelanin, a polymeric pigment in Pseudomonas, arises mainly from alterations in tyrosine degradation. The chemical structure of pyomelanin remains elusive due to its heterogeneous nature. Here, we report strain‐specific differences in pyomelanin structural features across Pseudomonas using PAO1 and PA14 reference strains carrying mutations in hmgA (a gene involved in pyomelanin synthesis), a melanogenic P. aeruginosa clinical isolate (PAM), and a melanogenic P. extremaustralis (PexM). UV spectra showed dual peaks for PAO1 and PA14 mutants and single peaks for PAM and PexM. FTIR phenol : alcohol ratio changes and complex NMR spectra indicated non‐linear polymers. UVC radiation survival increased with pyomelanin addition, correlating with pigment absorption attenuation. P. extremaustralis UVC survival varied with melanin source, with PAO1 pyomelanin being the most protective. These findings delineate structure‐based pyomelanin subgroups, having distinct physiological effects. [ABSTRACT FROM AUTHOR]

Bacterial infection is one of the most problematic issues for human health and the resistance of bacteria to traditional antibiotics is a matter of huge concern. Therefore, research is focusing on the development of new strategies to efficiently kill these microorganisms. Recently, melanin is starting to be investigated for this purpose. Indeed, this very versatile material presents outstanding photothermal properties, already studied for photothermal therapy, which can be very useful for the light-induced eradication of bacteria. In this review, we present antibacterial melanin applications based on the photothermal effect, focusing both on the single action of melanin and on its combination with other antibacterial systems. Melanin, also thanks to its biocompatibility and ease of functionalization, has been demonstrated to be easily applicable as an antimicrobial agent, especially for the treatment of local infections. [ABSTRACT FROM AUTHOR]

Objective Methods Results Conclusion Hydrolyzed conchiolin protein (HCP) derived from pearl and nacre extracts exerts skin‐lightening effects; however, the underlying molecular mechanisms are not fully understood. Herein, we investigated the effect of HCP on melanogenesis and the signalling pathways involved.B16F10 cells and PIG cells were treated with HCP to verify its ability to inhibit melanin. Western Blot, immunofluorescence, and flow cytometry methods were performed to investigate the effect of HCP on melanogenesis signalling pathway proteins. The inhibitors were used to further validate the effect of HCP on PKA/CREB and MEK/ERK signalling pathways. To further evaluate the whitening ability of HCP, changes in melanin were detected using 3D melanin skin model and zebrafish model.HCP was found to significantly inhibit melanin synthesis and decrease the expression of melanogenesis‐related proteins, such as microphthalmia‐associated transcription factor (MITF), tyrosinase, and tyrosinase‐related protein‐2, in a dose‐dependent manner. Additionally, we revealed that HCP suppresses melanogenesis via the regulation of the PKA/cAMP response element‐binding (CREB) and MEK/extracellular signalling‐regulated kinase (ERK) signalling pathways. Using 3D melanin skin models, we demonstrated that HCP can achieve skin‐lightening effects by improving apparent chroma, increasing apparent brightness, and inhibiting melanin synthesis. Furthermore, HCP exhibits skin‐whitening effects in a zebrafish model.These results suggest that HCP suppresses the melanogenesis signalling cascade by inhibiting the PKA/CREB, MEK/ERK signalling pathway and downregulating MITF and its downstream signalling pathways, resulting in decreased melanin synthesis. In summary, HCP is a potential anti‐pigmentation agent with promising applications in cosmetics and pharmaceutical products. [ABSTRACT FROM AUTHOR]

Aims The Gα subunit is a major component of heterotrimeric G proteins, which play a crucial role in the development and pathogenicity of several model fungi. However, its detailed function in the causal agent of pear black spot (Alternaria alternata) is unclear. Our aim was to understand the characteristics and functions of AaGA1 in A. alternata. Methods and results AaGA1 was cloned from A. alternata in this study, which encodes 353 amino acids and has a "G-alpha" domain. Mutant ΔAaGA1 resulted in reduced vegetative growth, conidiation, and spore germination. Especially, mutant ΔAaGA1 produced only fewer conidia on the V8A medium, and spore formation-related genes AbaA, BrlA , and WetA were significantly downregulated. More tolerance against cell wall-inhibiting agents was observed after the deletion of AaGA1. Moreover, AaGA1 deletion led to a significant reduction in melanin and toxin production. Interestingly, deletion of AaGA1 resulted in defective appressorium-like formations, complete loss of the ability to penetrate cellophane, and decreased infection on non-wound inoculated tobacco leaves. Cell wall-degrading enzyme-related genes PME, CL, Cut2 , and LC were significantly downregulated in mutant ΔAaGA1 mutant, significantly reducing virulence on wound-inoculated pear fruits. Conclusions The G protein alpha subunit AaGA1 is indispensable for fungal development, appressorium-like formations, and pathogenicity in A. alternata. [ABSTRACT FROM AUTHOR]

Anal cancer is uncommon, comprising 2.2% of gastrointestinal cancers. Squamous cell carcinoma (SCC) is the most common; while perianal basal cell carcinoma (BCC) is rare, representing only 0.2% of anorectal malignancies. BCC, associated with sun exposure and immunosuppression, often resembles benign conditions and manifests as perianal ulcers or masses. Histologically, BCC exhibits basaloid tumor cells with distinct patterns. Despite its rarity, accurate diagnosis is crucial. We expose a case study of a 59-year-old male, previously healthy, that presented with hematochezia and perianal pain, leading to a diagnosis of lower gastrointestinal bleeding. Colonoscopy was needed, and a biopsy revealed an ulcerated, indurated lesion involving the left lateral hemorrhoidal bundle, diagnosed as pigmented basaloid carcinoma. Microscopic examination showed malignant nests of cells with peripheral nuclear palisading, melanocytes, and melanin pigment. Immunohistochemistry confirmed positivity for p63, CK5/6, and BCL2. Respect the treatment, due to the involvement of the anal sphincteric muscle, radiotherapy was chosen. [ABSTRACT FROM AUTHOR]

Melanin naturally exists in organisms and is synthetized by tyrosinase (TYR); however, its over-production may lead to aberrant pigmentation and skin conditions. Loquat (Eriobotrya japonica (Thunb.) Lindl.) flowers contain a variety of bioactive compounds, while studies on their suppressive capabilities against melanin synthesis are limited. Loquat flower isolate product (LFP) was obtained by ethanol extraction and resin purification, and its inhibitory efficiency against TYR activity was investigated by enzyme kinetics and multiple spectroscopy analyses. In addition, the impact of LFP on melanin synthesis-related proteins' expression in mouse melanoma B16 cells was analyzed using Western blotting. HPLC-MS/MS analysis indicated that LFP was composed of 137 compounds, of which 12 compounds, including flavonoids (quercetin, isorhamnoin, p-coumaric acid, etc.) and cinnamic acid and its derivatives, as well as benzene and its derivatives, might have TYR inhibitory activities. LFP inhibited TYR activity in a concentration-dependent manner with its IC50 value being 2.8 mg/mL. The inhibition was an anti-competitive one through altering the enzyme's conformation rather than chelating copper ions at the active center. LFP reduced the expression of TYR, tyrosinase-related protein (TRP) 1, and TRP2 in melanoma B16 cells, hence inhibiting the synthesis of melanin. The research suggested that LFP had the potential to reduce the risks of hyperpigmentation caused by tyrosinase and provided a foundation for the utilization of loquat flower as a natural resource in the development of beauty and aging-related functional products. [ABSTRACT FROM AUTHOR]

Melanocytes evolved to produce the melanin that gives colour to our hair, eyes and skin. The melanocyte lineage also gives rise to melanoma, the most lethal form of skin cancer. The melanocyte lineage differentiates from neural crest cells during development, and most melanocytes reside in the skin and hair, where they are replenished by melanocyte stem cells. Because the molecular mechanisms necessary for melanocyte specification, migration, proliferation and differentiation are co-opted during melanoma initiation and progression, studying melanocyte development is directly relevant to human disease. Here, through the lens of advances in cellular omic and genomic technologies, we review the latest findings in melanocyte development and differentiation, and how these developmental pathways become dysregulated in disease. [ABSTRACT FROM AUTHOR]

This paper aims to highlight the physiological actions exerted by eumelanin present in several organs/tissues of the human body and to rationalise the often conflicting functional roles played by this biopolymer on the basis of its peculiar properties. Besides pigmentary disorders, a growing number of organ injuries and degenerative pathologies are presently ascribed to the modification of physiological eumelanin levels in terms of alterations in its chemical/structural features, and of a partial loss or uneven distribution of the pigment. The present review analyses the more recent research dedicated to the physiological and pathological actions of eumelanin and provides an insight into some melanogenesis-associated diseases of the skin, eye, ear, and brain, including the most significant neurodegenerative disorders. Also described are the potentialities of therapies based on the localised supply of exogeneous EU and the opportunities that EU produced via synthetic biology offers in order to redesign therapeutical and diagnostic applications. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Melanin is a crucial pigment in melanomagenesis. Its fluorescence in human tissue is exceedingly weak but can be detected through advanced laser spectroscopy techniques. The spectral profile of melanin fluorescence distinctively varies among melanocytes, nevomelanocytes, and melanoma cells, with melanoma cells exhibiting a notably "red" fluorescence spectrum. This characteristic enables the diagnosis of melanoma both in vivo and in histological samples. Neuromelanin, a brain pigment akin to melanin, shares similar fluorescence properties. Its fluorescence can also be quantified with high spectral resolution using the same laser spectroscopic methods. Documented fluorescence spectra of neuromelanin in histological samples from the substantia nigra substantiate these findings. Our research reveals that the spectral behavior of neuromelanin fluorescence mirrors that of melanin in melanomas. This indicates that the typical red fluorescence is likely influenced by the microenvironment around (neuro)melanin, rather than by direct pigment interactions. Our ongoing studies aim to further explore this distinctive "red" fluorescence. We have observed this red fluorescence spectrum in post-mortem measurements of melanin in benign nevus. The characteristic red spectrum is also evident here (unlike the benign nevus in vivo), suggesting that hypoxia may contribute to this phenomenon. Given the central role of hypoxia in both melanoma development and treatment, as well as in fundamental Parkinson's disease mechanisms, this study discusses strategies aimed at reinforcing the hypothesis that red fluorescence from (neuro)melanin serves as an indicator of hypoxia. [ABSTRACT FROM AUTHOR]

Domestic animals have multiple phenotypes of skin and coat color, which arise from different genes and their products, such as proteins and metabolites responsible with melanin deposition. However, the complex regulatory network of melanin synthesis remains to be fully unraveled. Here, the skin and tongue tissues of Liangshan black sheep (black group) and Liangshan semi-fine-wool sheep (pink group) were collected, stained with hematoxylin–eosin (HE) and Masson–Fontana, and the transcriptomic and metabolomic data were further analyzed. We found a large deposit of melanin granules in the epidermis of the black skin and tongue. Transcriptome and metabolome analysis identified 744 differentially expressed genes (DEGs) and 443 differentially expressed metabolites (DEMs) between the pink and black groups. Gene ontology (GO) and Kyoto encyclopedia of genes and genomes (KEGG) enrichment analyses revealed the DEGs and DEMs were mainly enriched in the pathways of secondary metabolic processes, melanin biosynthesis processes, melanin metabolism processes, melanosome membranes, pigment granule membranes, melanosome, tyrosine metabolism, and melanogenesis. Notably, we revealed the gene ENSARG00020006042 may be a family member of YWHAs and involved in regulating melanin deposition. Furthermore, several essential genes (TYR, TYRP1, DCT, PMEL, MLANA, SLC45A2) were significantly associated with metabolite prostaglandins and compounds involved in sheep pigmentation. These findings provide new evidence of the strong correlation between prostaglandins and related compounds and key genes that regulate sheep melanin synthesis, furthering our understanding of the regulatory mechanisms and molecular breeding of pigmentation in sheep. [ABSTRACT FROM AUTHOR]

Melanosomes are specialized membrane-bound organelles where melanin is synthesized and stored. The levels of melanin can be effectively reduced by inhibiting melanin synthesis or promoting melanosome degradation via autophagy. Ceramide, a key component in the metabolism of sphingolipids, is crucial for preserving the skin barrier, keeping it hydrated, and warding off the signs of aging. Our preliminary study indicated that a long-chain C22-ceramide compound (Ehux-C22) isolated from the marine microalga Emiliania huxleyi, reduced melanin levels via melanosomal autophagy in B16 cells. Recently, microRNAs (miRNAs) were shown to act as melanogenesis-regulating molecules in melanocytes. However, whether the ceramide Ehux-C22 can induce melanosome autophagy at the post-transcriptional level, and which potential autophagy-dependent mechanisms are involved, remains unknown. Here, miR-199a-3p was screened and identified as a novel upregulated miRNA in Ehux-C22-treated B16 cells. An in vitro high melanin expression model in cultured mouse melanoma cells (B16 cells) was established by using 0.2 μM alpha-melanocyte-stimulating hormone(α-MSH) and used for subsequent analyses. miR-199a-3p overexpression significantly enhanced melanin degradation, as indicated by a reduction in the melanin level and an increase in melanosome autophagy. Further investigation demonstrated that in B16 cells, Ehux-C22 activated miR-199a-3p and inhibited mammalian target of rapamycin(mTOR) level, thus activating the mTOR-ULK1 signaling pathway by promoting the expression of unc-51-like autophagy activating kinase 1 (ULK1), B-cell lymphoma-2 (Bcl-2), Beclin-1, autophagy-related gene 5 (ATG5), and microtubule-associated protein light chain 3 (LC3-II) and degrading p62. Therefore, the roles of Ehux-C22-regulated miR-199a-3p and the mTOR pathway in melanosomal autophagy were elucidated. This research may provide novel perspectives on the post-translational regulation of melanin metabolism, which involves the coordinated control of melanosomes. [ABSTRACT FROM AUTHOR]

1. Melanin distribution typically exhibits a gradient dilution along the dorsal-ventral axis of the body, including in domestic geese. However, the specific genes and molecular mechanisms responsible for this melanin distribution pattern remain incompletely understood. 2. The transcriptomic comparisons were conducted at three embryonic stages, specifically on embryonic d 15 (E15), 22 (E22), and 29 (E29), between the pigmented dorsal skin and the depigmented distal foot. 3. Differentially expressed genes (DEGs) associated with melanin synthesis were identified, particularly TYR, TYRP1, and EDNRB2, which exhibited significantly higher expression levels in the dorsal skin at E15 and E22. However, expression levels significantly decreased in later stages (E29). 4. The ASIP gene showed remarkably high-expression levels in the distal feet compared to the dorsal skin post-E22 stage (log2FC: 5.31/6.88 at E22/E29). Gene Ontology (GO) enrichment analysis detected eight terms associated with melanin synthesis and melanosome formation (p < 0.05), including melanosome membrane (GO: 0033162) and melanin biosynthetic process (GO: 0042438). Additionally, KEGG pathway analysis showed significant enrichment of the melanogenesis pathway (hsa004916) at d 22 (E22). [ABSTRACT FROM AUTHOR]

Background: Sirtuin 7 (SIRT7) is pivotal in diverse diseases progression. Importantly, SIRT7 is associated with melanin production. However, whether SIRT7 regulates vitiligo is unclear. Therefore, we aimed to investigate the effects of SIRT7 on pigmentation and the modification of glucose 6‐phosphate dehydrogenase (G6PD). Methods: After knockdown SIRT7 and G6PD, pigmentation of melanocytes was evaluated using commercial kits, immunofluorescence, and Western blot analysis. The succinylation of G6PD mediated by SIRT7 was analyzed using co‐immunoprecipitation, immunofluorescence, Western blot analysis, and cycloheximide‐chase experiment. Results: We found that SIRT7 was highly expressed in vitiligo skin lesions. Knockdown of SIRT7 increased tyrosinase activity, melanin content, and the levels of α‐melanocyte‐stimulating hormone, MITF, TYR, TRP1, and TRP2. Additionally, SIRT7 directly interacted with G6PD. Silenced SIRT7 promoted the succinylation of G6PD and enhanced its protein stability. G6PD knockdown reversed the effect of reduced SIRT7 expression on melanin production. Conclsuion: Silencing of SIRT7 promotes pigmentation of melanocytes by succinylating G6PD, suggesting that SIRT7‐mediated G6PD desuccinylation may promote vitiligo progression. [ABSTRACT FROM AUTHOR]

Background: Our goal was to investigate linkages between skin color parameters and skin hydration. Since most prior studies focused on stratum corneum hydration, we focused on epidermal and dermal hydration in relation to skin color parameters in both sexes. Materials and Methods: Thirty adults (16 female) with an age ± SD of 24.3 ± 0.6 years participated. Three sites on both volar forearms were evaluated for melanin index (MI), erythema index (EI), Individual Typology Angle (ITA), tissue dielectric constant (TDC) values to depths of 0.5 mm (TDC0.5) and 2.5 mm (TDC2.5), and Fitzpatrick skin type (FST). Results: MI and EI were highly correlated (r = 0.800, p < 0.001) with maximum differences in MI and ITA along the arm of 3% and 6.3% with no difference between arms. Male MI was greater than females (p < 0.01). Male TDC2.5 was 36.1 ± 5.4 and correlated with EI (r = 0.231, p = 0.035). Contrastingly, female TDC25 was 28.5 ± 3.6 with no correlation with EI but was correlated with MI (r = −0.301, p = 0.003). These differential patterns held true for TDC0.5. For both sexes, FST and ITA were highly correlated (r = −0.756, p < 0.001). Conclusions: The findings revealed several correlations between skin color parameters and hydration that differed between males in females in some cases. The observed correlations may indicate that melanin may differentially impact water‐holding capacity between sexes and provides a future research target. Further, these initial findings also may hold significance for dermatological assessments and the customization of skincare treatments tailored to individual skin types and demographics. [ABSTRACT FROM AUTHOR]

Background: Skin "yellowness" is an abstract and subjective term, without a definitive measurement protocol. Objectives were to analyze Chinese women's self‐perception of skin yellowness and associated parameters and identify objective clinical measurements that correlate with these perceptions. Methods: Following focus group discussions, criteria for skin yellowness were defined, and validated by volunteer rankings of facial images. A typology study of 185 women was performed. Participants were grouped into yellow (Color Uniformity, Brightness and Transparency (CUBT) yellow scale grade > 3, chromameter b* value > 16) and non‐yellow (CUBT yellow scale grade < 2, b* value < 14) groups. Participants self‐evaluated their skin on yellowness, transparency, skin uniformity, dullness, radiance, oiliness, and texture. Expert assessments were performed to grade sebaceous pores, ocular area pigmentation, pigmentary spots and CUBT scores. Instrumental analysis of the skin was employed using corneometer, sebumeter, mexameter chromameter, and AGE reader. Results: Women in the yellow group self‐evaluated their skin as significantly duller, less uniform, and less radiant than women in the non‐yellow group (P ≤ 0.05). Higher levels of ocular area pigmentation and lower facial skin uniformity and brightness (P < 0.001) were observed in women with yellow skin. CUBT expert grading showed lower pink skin color, but significantly higher beige, yellow, and olive pigmentation (P ≤ 0.05) in women in the yellow skin group. Melanin and b* values were significantly higher in women with yellow skin while L value was significantly lower. Conclusion: Self‐perceived skin yellowness in Chinese women correlates to chromameter and mexameter measurements, as well as expert evaluation of ocular pigmentation and CUBT parameters. [ABSTRACT FROM AUTHOR]

Brilliant, diverse colour ornaments of birds were one of the crucial cues that led Darwin to the idea of sexual selection. Although avian colouration plays many functions, including concealment, thermoregulation, or advertisement as a distasteful prey, a quality‐signalling role in sexual selection has attracted most research attention. Sexually selected ornaments are thought to be more susceptible to external stressors than naturally selected traits, and as such, they might be used as a test for environmental quality. For this reason, the last two decades have seen numerous studies on the impact of anthropogenic pollution on the expression of various avian colour traits. Herein, we provide the first meta‐analytical summary of these results and examine whether there is an interaction between the mechanism of colour production (carotenoid‐based, melanin‐based and structural) and the type of anthropogenic factor (categorised as heavy metals, persistent organic pollutants, urbanisation, or other). Following the assumption of heightened condition dependence of ornaments under sexual selection, we also expected the magnitude of effect sizes to be higher in males. The overall effect size was close to significance and negative, supporting a general detrimental impact of anthropogenic pollutants on avian colouration. In contrast to expectations, there was no interaction between pollution types and colour‐producing mechanisms. Yet there were significant differences in sensitivity between colour‐producing mechanisms, with carotenoid‐based colouration being the most affected by anthropogenic environmental disturbances. Moreover, we observed no significant tendency towards heightened sensitivity in males. We identified a publication gap on structural colouration, which, compared to pigment‐based colouration, remains markedly understudied and should thus be prioritised in future research. Finally, we call for the unification of methods used in colour quantification in ecological research to ensure comparability of results among studies. [ABSTRACT FROM AUTHOR]

Melanins are heterogenous biopolymers produced by many macro and microorganisms. They enhance the ecological fitness of the producer organisms by improving their virulence and protecting them from radiation, osmotic and heat stresses. Fungi synthesise either DOPA or DHN melanin and deposit them on their cell walls. Some fungal isolates produce water soluble melanin (pyomelanin) which is excerted out of the hyphae into the surrounding environment. Pyomelanin, a polymer of homogentisate, exhibits antimicrobial, UV screening, antioxidative, and anti-inflammatory activities and recent studies also show that pyomelanin could find use in space travel as radiation shield. However, scant literature is available on fungi with ability to produce pyomelanin. We report for the first time that Amorosia littoralis occurs as a root endophyte in mangrove species including Avicennia marina , Bruguiera cylindrica and Bruguiera gymnorhiza and produces pyomelanin. Considering the various technological uses of pyomelanin, this study underscores the need to explore fungi of different habitats to identify hyperproducers and to obtain chemically diverse pyomelanin. [ABSTRACT FROM AUTHOR]

Glossogyne tenuifolia (Labill.) Cass. ex Cass (Compositae) is a herbaceous plant that is endemic to Taiwan. Traditional Chinese Medicine has utilized it as a treatment for fever, inflammation, and liver preservation. Recent research has unveiled its bioactivities, including anti-inflammation, anti-cancer, antiviral, antioxidant, anti-fatigue, hepatoprotection, and immune modulation elements. Nevertheless, its effect on skin health remains to be investigated. Thus, we investigated the impact of G. tenuifolia essential oil (GTEO) on forskolin (FRK)-induced melanin biosynthesis and its mechanisms in B16-F10 murine melanoma in vitro. Treatment of GTEO resulted in a substantial decrease in FRK-induced melanin production, accompanied by a significant decrease in tyrosinase mRNA and protein expression levels. Additionally, our data demonstrated that the decrease in tyrosinase expression resulted from the suppression of MITF, as indicated by the reduced movement of MITF into the cell nucleus. Moreover, GTEO prompted a prolonged ERK1/2 activation, leading to the decline of MITF through proteasomal degradation, and it was verified that GTEO had no inhibitory impact on MITF activity in ERK1/2 inhibitor-treated cells. Additional studies demonstrated that α-pinene and D-limonene, which are the primary components in GTEO, showed strong melanin and tyrosinase inhibitory effects, indicating that α-pinene and D-limonene may contribute to its anti-melanogenic effects. Collectively, these data presented compelling proof that GTEO, along with its primary components α-pinene and D-limonene, show great potential as natural sources for developing innovative skin-whitening agents in the field of cosmetics. [ABSTRACT FROM AUTHOR]

Melasma is a pathology with multifactorial causes that results in hyperpigmentation of sun-exposed areas, particularly facial skin. New treatments targeting the different factors regulating this condition need to be effective with and have limited adverse effects. Here, we describe a novel combination of two natural compounds (apigenin and phloretin) that has synergistic effects regulating melanogenesis in vitro. Both compounds inhibit Wnt-stimulated melanogenesis and induce autophagy in melanocytes. Apigenin induces DKK1, a Wnt pathway inhibitor, and reduces VEGF, a melanogenesis and proangiogenic factor, in fibroblasts. Moreover, apigenin induces miR-675, a melanogenesis inhibitor miRNA that is reduced in melasma skin in melanocytes. Both compounds showed senomorphic effects by regulating extracellular-matrix-related genes in senescent fibroblasts. Topical application of the compounds also showed significant melanin reduction in a reconstructed human epidermis after 7 days. Thus, the combination of apigenin and phloretin shows promising results as an effective topical treatment of skin hyperpigmentation conditions. [ABSTRACT FROM AUTHOR]

The melanocortin‐1 receptor (MC1R) is a G protein‐coupled receptor that plays a pivotal role in human skin pigmentation, melanin synthesis, redox homeostasis and inflammation. Loss‐of‐function MC1R variants suppress G protein‐coupled receptor coupling or cell surface expression leading to a decrease in adenyl cyclase activation and intracellular levels of cyclic adenosine monophosphate. Chronic activation of MC1R can occur in certain medical conditions such as Addison's disease and physiologic states such as pregnancy melasma. MC1R activation is more commonly caused by environmental exposure to ultraviolet (UV) radiation. Approved pharmacologic melanocortin agonists that activate MC1R signalling in a targeted manner or as a bystander effect have recently become available for erythropoietic protoporphyria, sexual desire disorders, monogenic obesity and syndromic obesity. Further, small peptide analogues of α–melanocortin‐stimulating hormone, human MC1R selective agonists, are photoprotective, decreasing the adverse impact of UV radiation (a primary risk factor for skin cancer) and are being investigated as potential chemoprevention strategies. MC1R activation through induction of UV‐protective skin pigmentation increased DNA repair, and control of aberrant cell growth may reduce the risk of melanoma but importantly does not prevent melanoma particularly in individuals with risk factors and regular skin examination remains critical in high‐risk individuals. [ABSTRACT FROM AUTHOR]

AbstractPlant melanin, a natural pigment, has gained significant attention recently due to its potential therapeutic and industrial applications. In this study, melanin pigments were extracted from Nigerseed hulls (NH) via alkali and acid extraction methods, followed by acid hydrolysis, organic solvent treatment, and repeated precipitation. The solubility of NH melanin was assessed, revealing solubility in alkali and dimethyl sulfoxide (DMSO) but insolubility in other common organic solvents. High-performance liquid chromatography (HPLC) was employed to measure the purity of NH melanin in comparison to standard melanin, while elemental analysis indicated a similarity between melanin extracted from nigerseed hulls and the standard counterpart. LC-MS data revealed a molecular weight of NH melanin. Furthermore, the stability of melanin was evaluated under varying conditions including temperature, oxidants, reducing agents, light exposure, and metal ion presence. Results demonstrated significant effects of Mg2+, Cu2+, and Fe2+ metal ions on melanin stability, with a minor effect observed for Ca2+, while sodium hyposulfite was found to destabilize the pigments. Our findings suggest that nigerseed hulls hold promise as a novel source for efficient melanin production, with potential applications in the food sector, food packaging, and biomedical fields. [ABSTRACT FROM AUTHOR]

There have been worldwide reports of chromatic aberrations in bats, most striking among which is albinism. Albinism is an inherited, hypo-pigmentary state characterised by a complete lack of melanin. Albinistic individuals have pale skin, white fur, and pinkishred eyes. Here we report the first record of albinism in Lesser Woolly Horseshoe Bat Rhinolophus beddomei. During a bat survey in Goa, India; a single individual of albino Lesser Woolly Horseshoe Bat was recorded along with a normally coloured conspecific individual from a small shelter with tiled roof. We confirm the species identity of this bat based on its morphology, and acoustic characteristics of its echolocation call. We further update the list of colour aberrations in bats reported from india. [ABSTRACT FROM AUTHOR]

Background: Sophora flavescens, a traditional Chinese medicine for treating conditions associated with abnormal skin pigmentation, contains flavonoids with inhibitory effects on tyrosinase. However, their mechanisms of action and their modulatory effects on melanogenesis remain unclear. Methods: Herein, a group of prenylated flavonoids was identified from S. flavescens extracts and their inhibitory activities on mushroom tyrosinase were evaluated. The anti-melanogenesis effects of these prenylated flavonoids were investigated in cellular (with murine melanoma cells) and animal (with zebrafish) models. Results: Prenylated flavonoids including isoanhydroicaritin (IAI), kurarinone (KR), and sophoraflavanone G (SG) were the major active constituents in S. flavescens extracts with anti-tyrosinase activity (IC50 = 0.7, 7.1, and 6.7 µM, respectively). Enzyme kinetic assays showed that IAI, KR, and SG had a mixed type of tyrosinase inhibition, supported by data from computational docking. Notably, KR at concentrations of 5 and 10 µM enhanced intracellular tyrosinase activity and stimulated melanin production in B16F10 cells, whereas SG and IAI did not exhibit significant activity. Further studies with the zebrafish model showed that IAI (80 and 160 µM) inhibited melanin biosynthesis by about 30.0% while KR (20 µM) stimulated melanogenesis by 36.9%. Furthermore, a zebrafish depigmentation model supported the anti-melanogenesis effect of IAI (80 and 160 µM) by 33.0% and 34.4%, respectively. Conclusion: In summary, IAI was identified as a tyrosinase inhibitor with an antimelanogenic effect and KR was an enhancer for melanin production in B16F10 cells and zebrafish. Findings from the current study suggest that IAI and KR from S. flavescens may exert contrasting effects in the modulation of melanin production, providing important insights into the development of S. flavescens as a cosmeceutical or medicinal ingredient. [ABSTRACT FROM AUTHOR]

Melanoma is one of the most aggressive and lethal types of cancer owing to its metastatic propensity and chemoresistance property. An alternative therapeutic option is photodynamic and photothermal therapies (PDT/PTT), which employ near-infrared (NIR) light to generate heat and reactive oxygen species (ROS). As per previous reports, Melanin (Mel), and its synthetic analogs (i.e. polydopamine nanoparticles) can induce NIR light-mediated heat energy, thereby selectively targeting and ameliorating cancer cells. Similarly, chlorin e6 (Ce6) also has high ROS generation ability and antitumor activity against various types of cancer. Based on this tenet, In the current study, we have encapsulated Mel-Ce6 in a polydopamine (PDA) nanocarrier (MCP NPs) synthesized by the oxidation polymerization method. The hydrodynamic diameter of the synthesized spherical MCP NPs was 139 ± 10 nm. The MCP NPs, upon irradiation with NIR 690 nm laser for 6 min, showed photothermal efficacy of more than 50 °C. Moreover, the red fluorescence in the MCP NPs due to Ce6 can be leveraged for diagnostic purposes. Further, the MCP NPs exhibited considerable biocompatibility with the L929 cell line and exerted nearly 70% ROS-mediated cytotoxicity on the B16 melanoma cell line after the laser irradiation. Thus, the prepared MCP NPs could be a promising theranostic agent for treating the B16 melanoma cancer. [ABSTRACT FROM AUTHOR]

Melanin‐concentrating hormone (MCH) neurons can co‐express several neuropeptides or neurotransmitters and send widespread projections throughout the brain. Notably, there is a dense cluster of nerve terminals from MCH neurons in the lateral septum (LS) that innervate LS cells by glutamate release. The LS is also a key region integrating stress‐ and anxiety‐like behaviours, which are also emerging roles of MCH neurons. However, it is not known if or where the MCH peptide acts within the LS. We analysed the projections from MCH neurons in male and female mice anteroposteriorly throughout the LS and found spatial overlap between the distribution pattern of MCH‐immunoreactive (MCH‐ir) fibres with MCH receptor Mchr1 mRNA hybridization or MCHR1‐ir cells. This overlap was most prominent along the ventral and lateral border of the rostral part of the LS (LSr). Most MCHR1‐labelled LS neurons lay adjacent to passing MCH‐ir fibres, but some MCH‐ir varicosities directly contacted the soma or cilium of MCHR1‐labelled LS neurons. We thus performed whole‐cell patch‐clamp recordings from MCHR1‐rich LSr regions to determine if and how LS cells respond to MCH. Bath application of MCH to acute brain slices activated a bicuculline‐sensitive chloride current that directly hyperpolarized LS cells. This MCH‐mediated hyperpolarization was blocked by calphostin C, which suggested that the inhibitory actions of MCH were mediated by protein kinase C‐dependent activation of GABAA receptors. Taken together, these findings define potential hotspots within the LS that may elucidate the contributions of MCH to stress‐ or anxiety‐related feeding behaviours. Key points: Melanin‐concentrating hormone (MCH) neurons have dense nerve terminals within the lateral septum (LS), a key region underlying stress‐ and anxiety‐like behaviours that are emerging roles of the MCH system, but the function of MCH in the LS is not known.We found spatial overlap between MCH‐immunoreactive fibres, Mchr1 mRNA, and MCHR1 protein expression along the lateral border of the LS.Within MCHR1‐rich regions, MCH directly inhibited LS cells by increasing chloride conductance via GABAA receptor activation in a protein kinase C‐dependent manner.Electrophysiological MCH effects in brain slices have been elusive, and few studies have described the mechanisms of MCH action. Our findings demonstrated, to our knowledge, the first description of MCHR1 Gq‐coupling in brain slices, which was previously predicted in cell or primary culture models only. Together, these findings defined hotspots and mechanistic underpinnings for MCH effects such as in feeding and anxiety‐related behaviours. [ABSTRACT FROM AUTHOR]

Opsins are a class of transmembrane proteins encoded by opsin genes, and they play a variety of functional roles. Short wavelength-sensitive opsin 2 (sws2), one of the five classes of visual opsin genes, mainly senses blue light. Previous research has indicated that sws2 is essential for melanocyte formation in fish; however, its specific role in skin color differentiation remains to be elucidated. Here, we identified the sws2 gene in a prized reef-dwelling fish, Plectropomus leopardus. The full-length P. leopardus sws2 gene encodes a protein consisting of 351 amino acids, and exhibits substantial homology with other fish species. The expression of the sws2 gene was widespread across P. leopardus tissues, with high expression in eye and skin tissues. Through immunohistochemistry and in situ hybridization analyses, we discovered that the sws2 gene was primarily localized in the rod and cone cells of the retina, and epidermal cells of the skin. Furthermore, dsRNA interference was used for sws2 gene knockdown in living P. leopardus to elucidate its function in skin color differentiation. Black-color-related genes, melanin contents, and tyrosinase activity in the skin significantly decreased after sws2 knockdown (p < 0.05), but red-color-related genes and carotenoid and lutein contents significantly increased (p < 0.05). Retinoic acid injection produced the opposite results. Our results suggested that the sws2 gene influences P. leopardus skin color regulation by affecting vitamin synthesis and melanin-related gene expression levels. This study establishes a foundation for elucidating the molecular mechanisms by which sws2 regulates melanocyte formation in fish skin. [ABSTRACT FROM AUTHOR]

Cryomyces antarcticus, a melanized cryptoendolithic fungus endemic to Antarctica, can tolerate environmental conditions as severe as those in space. Particularly, its ability to withstand ionizing radiation has been attributed to the presence of thick and highly melanized cell walls, which—according to a previous investigation—may contain both 1,8‐dihydroxynaphthalene (DHN) and L‐3,4 dihydroxyphenylalanine (L‐DOPA) melanin. The genes putatively involved in the synthesis of DHN melanin were identified in the genome of C. antarcticus. Most important is capks1 encoding a non‐reducing polyketide synthase (PKS) and being the ortholog of the functionally characterized kppks1 from the rock‐inhabiting fungus Knufia petricola. The co‐expression of CaPKS1 or KpPKS1 with a 4′‐phosphopantetheinyl transferase in Saccharomyces cerevisiae resulted in the formation of a yellowish pigment, suggesting that CaPKS1 is the enzyme providing the precursor for DHN melanin. To dissect the composition and function of the melanin layer in the outer cell wall of C. antarcticus, non‐melanized mutants were generated by CRISPR/Cas9‐mediated genome editing. Notwithstanding its slow growth (up to months), three independent non‐melanized Δcapks1 mutants were obtained. The mutants exhibited growth similar to the wild type and a light pinkish pigmentation, which is presumably due to carotenoids. Interestingly, visible light had an adverse effect on growth of both melanized wild‐type and non‐melanized Δcapks1 strains. Further evidence that light can pass the melanized cell walls derives from a mutant expressing a H2B‐GFP fusion protein, which can be detected by fluorescence microscopy. In conclusion, the study reports on the first genetic manipulation of C. antarcticus, resulting in non‐melanized mutants and demonstrating that the melanin is rather of the DHN type. These mutants will allow to elucidate the relevance of melanization for surviving extreme conditions found in the natural habitat as well as in space. [ABSTRACT FROM AUTHOR]

Respiratory infections caused by the human fungal pathogen Aspergillus fumigatus are a major cause of mortality for immunocompromised patients. Exposure to these pathogens occurs through inhalation, although the role of the respiratory epithelium in disease pathogenesis has not been fully defined. Employing a primary human airway epithelial model, we demonstrate that fungal melanins potently block the post-translational secretion of the chemokines CXCL1 and CXCL8 independent of transcription or the requirement of melanin to be phagocytosed, leading to a significant reduction in neutrophil recruitment to the apical airway both in vitro and in vivo. Aspergillus-derived melanin, a major constituent of the fungal cell wall, dampened airway epithelial chemokine secretion in response to fungi, bacteria, and exogenous cytokines. Furthermore, melanin muted pathogen-mediated calcium fluxing and hindered actin filamentation. Taken together, our results reveal a critical role for melanin interaction with airway epithelium in shaping the host response to fungal and bacterial pathogens. Here, Reedy et al. use a human airway culture model to show that fungal melanin blocks the secretion of pro-inflammatory chemokines resulting in diminished immune responses to Aspergillus fumigatus and Pseudomonas aeruginosa. [ABSTRACT FROM AUTHOR]

Pigment patterns are incredibly diverse across vertebrates and are shaped by multiple selective pressures from predator avoidance to mate choice. A common pattern across fishes, but for which we know little about the underlying mechanisms, is repeated melanic vertical bars. To understand the genetic factors that modify the level or pattern of vertical barring, we generated a genetic cross of 322 F2 hybrids between two cichlid species with distinct barring patterns, Aulonocara koningsi and Metriaclima mbenjii. We identify 48 significant quantitative trait loci that underlie a series of seven phenotypes related to the relative pigmentation intensity, and four traits related to patterning of the vertical bars. We find that genomic regions that generate variation in the level of eumelanin produced are largely independent of those that control the spacing of vertical bars. Candidate genes within these intervals include novel genes and those newly-associated with vertical bars, which could affect melanophore survival, fate decisions, pigment biosynthesis, and pigment distribution. Together, this work provides insights into the regulation of pigment diversity, with direct implications for an animal's fitness and the speciation process. [ABSTRACT FROM AUTHOR]

Colour signals play pivotal roles in different communication systems, and the evolution of these characters has been associated with behavioural ecology, integumentary production processes and perceptual mechanisms of the species involved. Here, we present the first insight into the molecular and histological basis of skin colour polymorphism within a miniaturized species of pumpkin toadlet, potentially representing the lowest size threshold for colour polytypism in tetrapods. Brachycephalus actaeus exhibits a coloration ranging from cryptic green to conspicuous orange skin, and our findings suggest that colour morphs differ in their capability to be detected by potential predators. We also found that the distribution and abundance of chromatophores are variable in the different colour morphs. The expression pattern of coloration related genes was predominantly associated with melanin synthesis (including dct, edn1, mlana, oca2, pmel, slc24a5, tyrp1 and wnt9a). Up‐regulation of melanin genes in grey, green and brown skin was associated with higher melanophore abundance than in orange skin, where xanthophores predominate. Our findings provide a significant foundation for comparing and understanding the diverse pathways that contribute to the evolution of pigment production in the skin of amphibians. [ABSTRACT FROM AUTHOR]

Black soldier fly (BSF) melanin is a new supply of the brown-black pigment eumelanin. Given that eumelanin is a model bioelectronic material for applications such as medical devices and sensors, understanding BSF melanin's electrical properties is important to confirm its viability as an advanced material. Presented here is a systematic, hydration dependent alternating current study of BSF melanin utilising both H2O and D2O vapours. There is a clear difference between the vapours, enabling a thorough analysis including Nyquist plots with model circuit analysis, broad band dielectric spectroscopic modelling as well as applying the Trukhan model to understand free ion concentration and mobility changes as a function of hydration. We find that BSF melanin behaves similarly to previous reports on synthetic systems, and the analysis here sheds additional light on potential charge transport changes. Significantly, a key finding is that there are two different mobility mechanisms for ion transport depending on hydration. [ABSTRACT FROM AUTHOR]

While numerous studies have confirmed sexual selection for ornamental traits in animals, it remains unclear about how animals exaggerate ornamentation across traits. I found that some Asian barn swallows Hirundo rustica gutturalis possessed "pseudo‐tail spots" on their undertail coverts adjacent to a well‐known sexual signal, the white tail spots. A close inspection showed their remarkable resemblance, and, as a consequence, pseudo‐tail spots appear to add white spots to the uniformly black central tail feathers, increasing the total number and area of white spots when spread tails are viewed from below. Pseudo‐tail spots on the undertail covers do not incur any flight cost, unlike the white tail spots on the tail itself, and thus presence of pseudo‐tail spots can represent an initial stage of a deceptive elaboration as predicted by sexual selection theory (i.e., males can elaborate traits with no additional flight cost, uncoupling flight cost and trait expression). The frequency of pseudo‐tail spots in the study population remained low even a decade after the first observation (ca. 7%), but was higher compared to other populations (e.g., 1% in another Japanese population). The slow progress of evolution, perhaps due to the low detectability of the trait, provides a unique opportunity to observe contemporary evolution of ornament exaggeration across traits. Further research with wider spatial and temporal coverage is needed to better understand the evolutionary and ecological importance of the trait. [ABSTRACT FROM AUTHOR]

The quartz tuning fork (QTF) is a promising instrument for biosensor applications due to its advanced properties such as high sensitivity to physical quantities, cost-effectiveness, frequency stability, and high-quality factor. Nevertheless, the fork's small size and difficulty in modifying the prongs' surfaces limit its wide use in experimental research. Our study presents the development of a QTF immunosensor composed of three active layers: biocompatible natural melanin nanoparticles (MNPs), glutaraldehyde (GLU), and anti-IgG layers, for the detection of immunoglobulin G (IgG). Frequency shifts of QTFs after MNP functionalization, GLU activation, and anti-IgG immobilization were measured with an Asensis QTF F-master device. Using QTF immunosensors that had been modified under optimum conditions, the performance of QTF immunosensors for IgG detection was evaluated. Accordingly, a finite element method (FEM)-based model was produced using the COMSOL Multiphysics software program (COMSOL License No. 2102058) to simulate the effect of deposited layers on the QTF resonance frequency. The experimental results, which demonstrated shifts in frequency with each layer during QTF surface functionalization, corroborated the simulation model predictions. A modelling error of 0.05% was observed for the MNP-functionalized QTF biosensor compared to experimental findings. This study validated a simulation model that demonstrates the advantages of a simulation-based approach to optimize QTF biosensors, thereby reducing the need for extensive laboratory work. [ABSTRACT FROM AUTHOR]

To date, only 10 of the more than 30 fur colours that had been observed in American mink (Neogale vison) have been linked to specific genes. The Royal pastel fur colour is part of a large family of brownish colours that are quite similar to one another, making breeding and selecting processes more difficult. Here we carried out whole‐genome sequencing of five American minks with Royal pastel (b/b) phenotypes originating from two distinct mink populations. We identified an insertion of endogenous retroviral element type 1 (ERV1) into the first intron of the gene encoding the HPS3 protein, which regulates the trafficking of tyrosinase‐containing vesicles to maturing melanosomes. With Cas9‐targeted nanopore sequencing, we reconstructed the full‐length sequence of the 11.7 Kb ERV1 insertion and observed hypermethylation that spread to the HPS3 gene promoter region. These findings highlight the role of HPS3 in the formation of melanosomes and melanin, as well as the genetic process regulating the intensity and spectrum of hair colour. Moreover, in mink breeding projects, these data are also useful for tracking economically important fur qualities. [ABSTRACT FROM AUTHOR]

While current facial re‐ageing methods can produce realistic results, they purely focus on the 2D age transformation. In this work, we present an approach to transform the age of a person in both facial appearance and shape across different ages while preserving their identity. We employ an α‐(de)blending diffusion network with an age‐to‐α transformation to generate coarse structure changes, such as wrinkles. Additionally, we edit biophysical skin properties, including melanin and hemoglobin, to simulate skin color changes, producing realistic re‐ageing results from ages 10 to 80 years. We also propose a geometric neural network that alters the coarse scale facial geometry according to age, followed by a lightweight and efficient network that adds appropriate skin displacement on top of the coarse geometry. Both qualitative and quantitative comparisons show that our method outperforms current state‐of‐the‐art approaches. [ABSTRACT FROM AUTHOR]

Developing special textiles (for patients in hospitals for example) properties, special antimicrobial and anticancer, was the main objective of the current work. The developed textiles were produced after dyeing by the novel formula of natural (non-environmental toxic) pigments (melanin amended by microbial-AgNPs). Streptomyces torulosus isolate OSh10 with accession number KX753680.1 was selected as a superior producer for brown natural pigment. By optimization processes, some different pigment colors were observed after growing the tested strain on the 3 media. Dextrose and malt extract enhanced the bacteria to produce a reddish-black color. However, glycerol as the main carbon source and NaNO3 and asparagine as a nitrogen source were noted as the best for the production of brown pigment. In another case, starch as a polysaccharide was the best carbon for the production of deep green pigment. Peptone and NaNO3 are the best nitrogen sources for the production of deep green pigment. Microbial-AgNPs were produced by Fusarium oxysporum with a size of 7–21 nm, and the shape was spherical. These nanoparticles were used to produce pigments-nanocomposite to improve their promising properties. The antimicrobial of nanoparticles and textiles dyeing by nanocomposites was recorded against multidrug-resistant pathogens. The new nanocomposite improved pigments' dyeing action and textile properties. The produced textiles had anticancer activity against skin cancer cells with non-cytotoxicity detectable action against normal skin cells. The obtained results indicate to application of these textiles in hospital patients' clothes. [ABSTRACT FROM AUTHOR]

Background and Aim: Melanocytes are cells in the skin, hair, and eyes that generate pigment called melanin, which is primarily responsible for the pigmentation of these structures. These melanocytes, known as the Cochlear Melanocyte, are also present in the human ears (especially in the cochlea) and play a significant role in fostering endocochlear potential and preventing the odds of hearing loss. The current study investigated the relationship of skin pigment with cochlear function through distortion product otoacoustic emission in Indian skin type. Methods: A total of 120 participants aged between 17 to 25 were included using a purposive sampling technique. The subjects were further grouped based on a questionnaire on Fitzpatrick Skin Phototype (FSP) developed by Thomas Fitzpatrick (1975) and categorized as type III- type VI suitable for Indian skin types. Along with routine audiometric evaluations, the cochlear functioning was assessed using distortion product otoacoustic emissions. The standard group research design was used, and as data was normally distributed, multivariate analysis of variance was used to compare across groups. Results: The results of multivariate analysis of variance (MANOVA) showed no significant differences across the four groups for both amplitude and the slope of distortion product otoacoustic emissions. Conclusion: The present study using otoacoustic emissions revealed that the skin pigmentation did not affect cochlear functioning in the Indian population (type III through type VI) as seen in type I and II. [ABSTRACT FROM AUTHOR]

In our study, using chromatographic techniques, we isolated three bioactive compounds, which were structurally elucidated as (E)-2-(3-(3,4-dimethoxyphenyl)acrylamido)-N-methylbenzamide (1), 4-Hydroxyquinoline-2-carboxylic acid (2), and (E)-2-Cyano-3-(4-hydroxyphenyl)acrylic acid (3), using spectroscopic methods. The anti-melanogenic, anti-inflammatory, antioxidant, and anti-aging properties were evaluated in vitro by measuring the activity of pharmacological targets including tyrosinase, melanin, NF-κB, hyaluronidase, elastase, collagenase, and Nrf2. Our results show that compound 1 is the most active with IC50 values of 14.19 μM (tyrosinase inhibition), 22.24 μM (melanin inhibition), 9.82–12.72 μM (NF-κB inhibition), 79.71 μM (hyaluronidase inhibition), 80.13 μM (elastase inhibition), 76.59 μM (collagenase inhibition), and 116–385 nM (Nrf2 activation) in the THP-1, HEK001, WS1, and HMCB cells. These findings underscore the promising profiles of the aqueous extract of R. urticifolius at safe cytotoxic concentrations. Additionally, we report, for the first time, the isolation and characterisation of these nitrogenous compounds in the R. urticifolius species. Finally, compound 1, isolated from R. urticifolius, is a promising candidate for the development of more effective and safer compounds for diseases related to skin pigmentation, protection against inflammation, and oxidative stress. [ABSTRACT FROM AUTHOR]

Simple Summary: This paper addresses the complex diagnostic challenges of pigmented lesions in the oral mucosa, ranging from benign to potentially malignant conditions. Our study provides a narrative review with a clinical case overview to guide clinicians in differentiating these lesions. By classifying pigmented lesions based on clinical and histological features, we emphasize the need for a structured approach to diagnosis. The study incorporates a retrospective analysis of cases from our oral medicine experience, utilizing clinical pictures and relevant histology. Our findings aim to enhance early and precise diagnosis, improving patient management and outcomes in dental and medical practice. This paper examines the clinical differentiation of pigmented lesions in the oral mucosa, which poses significant diagnostic challenges across dental and medical disciplines due to their spectrum from benign to potentially malignant conditions. Through a literature review and analysis of clinical cases, this study clarifies current diagnostic methodologies, with an emphasis on differential diagnosis, to provide a practical guide for clinicians. The classification of pigmented lesions, such as endogenous, focal melanocytic, and multifocal pigmentation, based on clinical and histological features, highlights the necessity for a structured and informed approach. A retrospective examination of cases from our oral medicine and pathology clinic, coupled with analysis of photographic and histological records, aids in classifying these lesions. This fosters a better understanding and promotes informed discussions among clinicians, ultimately aiming to enhance early and precise diagnosis, thus improving patient management and outcomes. [ABSTRACT FROM AUTHOR]

In breast cancer, Targeted Axillary Dissection (TAD) allows for the selective excision of the sentinel lymph node (SLN) during primary tumor surgery. TAD consists of the resection of labelled SLNs prior to neoadjuvant chemotherapy (NACT). Numerous clinical and preclinical studies have explored the use of carbon-based colloids for SLN tattooing prior to NACT. However, carbon vectors show varying degrees of inflammatory reactions and, in about one fifth of cases, carbon particles migrate via the lymphatic pathway to other nodes, causing the SLN to mismatch the tattooed node. To overcome these limitations, in this study, we explored the use of melanin as a staining endogenous pigment. We synthesized and characterized melanin-loaded polymeric nanoparticles (Mel-NPs) and used them to tattoo lymph nodes in pig animal models given the similarity in the size of the human and pig nodes. Mel-NPs tattooed lymph nodes showed high identification rates, reaching 83.3% positive identification 16 weeks after tattooing. We did not observe any reduction in the identification as time increased, implying that the colloid is stable in the lymph node tissue. In addition, we performed histological and ultrastructural studies to characterize the biological behavior of the tag. We observed foreign-body-like granulomatous inflammatory responses associated with Mel-NPs, characterized by the formation of multinucleated giant cells. In addition, electron microscopy studies showed that uptake is mainly performed by macrophages, and that macrophages undergo cellular damage associated with particle uptake. [ABSTRACT FROM AUTHOR]

Epidermal melanin unit integrity is crucial for skin homeostasis and pigmentation. Epidermal growth factor (EGF) receptor (EGFR) is a pivotal player in cell growth, wound healing, and maintaining skin homeostasis. However, its influence on skin pigmentation is relatively unexplored. This study investigates the impact and underlying mechanisms of EGFR inhibitors on skin pigmentation. We evaluated EGF and EGFR expression in various skin cells using quantitative real‐time PCR, Western blot, and immunofluorescence. EGF and EGFR were predominantly expressed in epidermal keratinocytes, and treatment with the EGFR tyrosine kinase inhibitors (EGFR‐TKIs) gefitinib and PD153035 significantly increased stem cell factor (SCF) and endothelin‐1 (ET‐1) expression in cultured keratinocytes. Enhanced melanocyte migration and proliferation were observed in co‐culture, as evidenced by time‐lapse live imaging and single‐cell tracking assays. Furthermore, topical application of gefitinib to guinea pig dorsal skin induced increased pigmentation and demonstrated efficacy in mitigating rhododendrol‐induced leukoderma. Suppression of EGF signaling indirectly enhanced skin pigmentation by upregulating SCF and ET‐1 in epidermal keratinocytes. This novel mechanism highlights the pivotal role of EGF signaling in regulating skin pigmentation, and topical EGFR‐TKI therapy at an appropriate dose may be a promising approach for depigmentation disorder management. [ABSTRACT FROM AUTHOR]

Tietz albinism‐deafness syndrome (TADS) is a rare and severe manifestation of Waardenburg syndrome that is primarily linked to mutations in MITF. In this report, we present a case of TADS resulting from a novel c.637G>C mutation in MITF (p.Glu213Gln; GenBank Accession number: NM_000248). A 3‐year‐old girl presented with congenital generalized hypopigmentation of the hair, skin, and irides along with complete sensorineural hearing loss. Histopathological and electron microscopy investigations indicated that this variant did not alter the number of melanocytes in the skin but significantly impaired melanosome maturation within melanocytes. Comprehensive melanin analysis revealed marked reductions in both eumelanin (EM) and pheomelanin (PM) rather than changes in the EM‐to‐PM ratio observed in oculocutaneous albinism. We conducted an electrophoretic mobility shift assay to investigate the binding capability of the identified variant to DNA sequences containing the E‐box motif along with other known variants (p.Arg217del and p.Glu213Asp). Remarkably, all three variants exhibited dominant‐negative effects, thus providing novel insights into the pathogenesis of TADS. This study sheds light on the genetic mechanisms underlying TADS and offers a deeper understanding of this rare condition and its associated mutations in MITF. [ABSTRACT FROM AUTHOR]