Skin Color Variation Research Articles

Sensitivity Response Analysis of Optical Surface Monitoring Systems Using the Fitzpatrick Scale: A Phantom Study

PurposeOptical Surface Monitoring systems (OSMS) have gained substantial attention in modern radiotherapy, specifically in the context of Surface Guided Radiation Therapy (SGRT) which offers real-time patient surface monitoring, ensuring accurate and effective radiotherapy treatments. The aim of this paper is to evaluate the OSMS camera sensitivity towards different skin tones, categorized according to the Fitzpatrick scale, a universal classification of human skin tones, using a phantom. Methods and MaterialThe study utilized Catalyst and SentinelTM OSMS systems (C-Rad, Uppsala, Sweden). The Alderson RANDO Female Pelvis phantom, located at the isocenter in CT simulation and treatment rooms, served as an experimental subject. Eighteen skin tone matching cotton cloths, selected based on Von Luschan's chromatic and Fitzpatrick scales, were wrapped around the phantom for sensitivity evaluation. Camera sensitivity was optimized by adjusting threshold/gain (100-600%) and integration time during individual scans in both rooms. Temporal response analysis spanned two months, with sixteen measurements for each OSMS taken in varying light conditions. ResultsThe OSMS systems successfully detected the surface of cloth-covered phantoms with varying mean (standard deviation) integration times: 550 (34) to 950 (43) μs for the Sentinel system and 2300 (71) to12000 (400) μs for the Catalyst system. The sensitivity parameters differed for each skin tone, with lighter skin requiring shorter integration times and gain/threshold values. Darker skin tones necessitated higher parameters for optimal surface images. The reliability of the systems declined with excessive parameters, leading to noise and compromised accuracy in patient positioning. ConclusionsOptimized sensitivity parameters tailored to individual skin tones are crucial for effective real-time patient surface monitoring in radiation therapy, as variations in skin colour can affect the accuracy of measurements. The precision of skin colour measurements in OSMS relies on carefully adjusting camera sensitivity parameters. However, careful consideration is essential, as larger values are required for darker skin tones, compromising reliability. This suggests the need for exploring alternative image guidance methods for patients with darker skin tones.

Outdoor noncontact respiratory measurements of unrestricted rhesus macaques (Macaca mulatta) using millimeter-wave radar.

Respiration is an invaluable signal that facilitates the real-time observation of physiological dynamics. In recent years, the advancement of noncontact measurement technology has gained momentum in capturing physiological activities in natural settings. This technology is anticipated to be found not only in humans but also in nonhuman primates. Currently, the predominant noncontact approach for nonhuman animals involves measuring vital signs through subtle variations in skin color. However, this approach is limited when addressing areas of the body covered with hair or when working in outdoor settings under fluctuating sunlight. To overcome this issue, we focused on noncontact respiratory measurements using millimeter-wave radar. Millimeter-wave radar systems, which employ millimeter waves that can penetrate animal fur and estimate respiration-derived periodic body motion, exhibit minimal susceptibility to sunlight interference. Thus, this method shows potential for conducting noncontact vital measurements in natural and outdoor settings. In this study, we validated a millimeter-wave radar methodology for capturing respiration in outdoor-housed rhesus macaques (Macaca mulatta). The radar was positioned beyond the captive enclosure and maintained at a distance >5 m from the target. Millimeter waves were transmitted to the target, and the reflected waves were used to estimate skin surface displacement associated with respiration. The results revealed periodic skin surface displacement, and the estimated respiratory rates weres within the reported range of respiratory rates for rhesus macaques. These results suggest the potential applicability of millimeter-wave radar for noncontact respiration monitoring in outdoor-living macaques without anesthesia or immobilization. The continued advancement of noncontact vital measurement technology will contribute to understanding primate mental and physical dynamics during their daily life.

P33 Skinvaders: gamification of the skin barrier to engage school-age children in the biology of the skin

Abstract Introduction and aims Public engagement is an essential part of research design. It provides opportunities for both scientists and the public to learn, and inspires the next generation of researchers. We are fortunate to have a public engagement centre within our institution, which contains digital games, an established and effective way to engage children. We developed a new game for school-age children to engage them in the Paediatric Human Cell Atlas, a collaborative project that aims to map single-cell profiles and spatial characterization of gene expression across human tissues and organs throughout development. Our aim was to develop a game that involved different skin cell types, variation in skin colour and common skin disorders. Methods Initial steps included brainstorming with our public engagement staff about content and then developing a lay summary and agreeing on the following key themes: the skin as a barrier, the cells of the skin, and eczema, a common skin disorder. The game was based on the arcade game Breakout. It features a customizable paddle representing the skin, demonstrating how changes in quantities of different skin components can change appearance/function (e.g. melanin production, adipocytes, hair follicles), which players must move across the screen to keep pathogens and allergens out and keep water and protein in. In the last level, barrier function is impaired by eczema and the children can catch cream to repair the barrier. Results The game was developed for our public engagement centre where it has undergone testing by target audiences. Conclusions We have created a game as an innovative way to engage and educate paediatric communities in our research. It was challenging to simplify scientific content for use in a game while staying true to the scientific concepts. We will increase reach by adapting the game for desktop and app-based formats.

Genome-wide association study reveals candidate genes critical for skin pigmentation in common carp (Cyprinus carpio) strains including koi

The differentiation and variation of body color in fish is an important component of biological evolution and phylogenetic research, and is influenced by several factors such as heredity, nutrition, physiological hormones and rearing conditions, with heredity being the most critical factor. An improved comprehension of the genetic regulation in different carp populations will facilitate future applications of precision breeding and pigment cell development-related genes editing. In this study, we used restriction site-associated DNA sequencing (2d-RAD) to determine the distribution characteristics of single nucleotide polymorphisms (SNPs) in eight common carp strains including six koi strains, i.e., Kohaku (Hb), Taisho (Dz), Showa (Zh), Golden (Hj), Matsukawabake (Sch) and Five-color (Ws), and two genetically improved breeding strains, i.e., FFRC No. 2 strain (Fr) and red FFRC strain (Hfr), and then SNP markers to resolve genetic information on the population structure and skin color formation of these strains. We found that most individuals of eight strains were clearly divided into eight clades. Genetic diversity within Fr, Sch and Ws is relatively high, while it is low within Dz, Hb and Hfr. A comparison between the populations revealed that Hfr and Ws have the highest degree of genetic differences, while Hb and Dz have the lowest. The GWAS analysis for two strategies identified several SNPs that are significantly related to skin color variation and affect melanin synthesis (ephrinb2, slc22a23, herc2, ephb2), carotenoid metabolism (oca2, bcmo1, bco2) and circadian rhythm(cipc). To summarize, our study provides some information on the genetic structure and diversity of Japanese koi and Chinese FFRC carp. Furthermore, based on the data obtained on relevant genes related to skin color differentiation and pigmentation, it can provide a theoretical basis for the subsequent integration of dominant traits and precision breeding in carps.

Abstract PO3-28-02: BODY-IMAGE DISTRESS IN BREAST CANCER SURVIVORS AND THEIR EVALUATION OF MEDICAL TATTOOING FOLLOWING SURGERY

Abstract A review of the literature reveals a high incidence of body-image distress among breast cancer survivors who have undergone surgery, which is a natural response to the significant changes in their appearance. Reconstructive surgery, utilizing implants or flaps, may be employed to restore breast size and shape. Medical tattooing can recreate the nipple-areola complex and decorative appliques can conceal scars and skin color variations. Both reconstructive surgery and medical tattoos are associated with patient-reported satisfaction, yet further research is necessary to understand their combined impact on body-image distress. To investigate this, a survey was distributed among national breast cancer support groups and advocacy organizations, yielding 207 responses from individuals meeting the study's criteria. The participants were categorized into two groups: those who received post-surgical medical tattoos (n = 61) and those who did not (n = 146). The study also examined how participants evaluated the cosmetic and decision satisfaction of patients who made various surgical and cosmetic intervention choices. This was accomplished by having participants rate images of patients who had received three types of intervention: mastectomy and reconstruction only, mastectomy and medical tattooing only, and mastectomy, reconstruction, and medical tattooing. Using linear regression and multilevel modeling that controlled for demographic and clinical factors associated with body-image distress, the findings demonstrated that participants with medical tattoos reported significantly lower levels of body-image distress, depressive symptoms, and perceived stress compared to those without medical tattoos. Furthermore, participants rated images of patients who underwent both reconstruction and medical tattooing post-mastectomy as having significantly higher cosmetic and decision satisfaction ratings than images of patients who received reconstruction or medical tattooing alone. This research expands on our understanding of body-image distress in survivors as a multidimensional construct and may serve to indicate potential means for intervention. Enhancing our understanding of how breast cancer treatment and surgery affects survivors' body-image distress may aid healthcare professionals in offering additional psychoeducation and recommendations. Furthermore, presenting information about medical tattooing as a complementary cosmetic option early in the treatment process allows patients the opportunity to consider it within the context of their overall treatment plan. Table. Linear regression results using BIBCQ as the outcome variable and medical tattoo group as the predictor variable with covariates included. Note. PHQ9 = Patient Health Questionnaire-9. PSS = Perceived Stress Scale. Citation Format: Miranda Proctor, Jeffrey Cassisi. BODY-IMAGE DISTRESS IN BREAST CANCER SURVIVORS AND THEIR EVALUATION OF MEDICAL TATTOOING FOLLOWING SURGERY [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO3-28-02.

Human Skin Detection and Segmentation Based on Convolutional Neural Networks

Human skin detection is the process of classifying the image pixels or regions as skin or non-skin. Skin detection has many applications, such as face tracking, skin diseases, nudity recognition, hand gestures, video surveillance, web content filtering, and pornographic content filtering. Skin detection is a challenging problem due to skin color variation, the human race, aging, gender, makeup, complex backgrounds, etc. This paper suggests detecting the skin region in the image and finding the location of the skin based on a convolutional neural network. In this proposal, the proposed CNN will be modified by adding two layers before the first layer of CNN and after the last layer of CNN. The main purpose of these layers is to prepare the input image by using a sliding window, which inputs an indexed small part of the image into the CNN. The network classifies each part as skin or non-skin and then sends the result into the second suggested layer. After processing all the image pixels, the non-skin blocks are mapped to the original image as black regions. The final image contains the skin regions with black in the background. The contribution of the proposed method is the ability to detect the skin from any part of the human body, unlike previous works, which focused on one part of the body. The input image is processed as blocks instead of the entire image as in the previous works, and then in the output, the original image is reconstructed. This method works well with most of the challenges that face the detection of skin, and finally, the designed network facilitates the localization and segmentation of the skin region almost accurately, while the previous networks focused on the classification of the image as skin or non-skin. The accuracy of the detection of skin when testing with images different from the training images was 95.4%.

Relationship between brightness perception and skin color influenced by experimental method

AbstractFacial brightness perception is affected by skin color. It was reported that reddish skin was matched with a higher lightness scale stimulus than yellowish skin among Japanese observers. However, this trend is inconsistent among Thai, Korean, Chinese, and European observers, implying the influence factors, such as ethnicity, environment, and judgment criteria. In this study, we investigated the influence of the experimental method on facial brightness perception using test stimulus images with constant lightness and different hue angles. We examined two instructions (“Appearance match” vs. “Brightness match”) and the scale stimulus for matching (a uniform color patch vs. a face image). We further conducted an impression evaluation experiment of the whole face. The matching results from the Japanese showed a similar trend in both instructions and scale stimuli under most conditions, suggesting that matched brightness is not influenced by instruction and the complexity of scale stimuli. The impression evaluation results were similar for Thai, Japanese, and Chinese observers, with reddish faces being evaluated with higher scores in brightness. Our findings suggest the influence of experimental methods on facial brightness judgment. The holistic judgment of facial brightness would be universal among different East Asian groups, at least for the range of variation in skin color we used.

Remote Heart Rate Estimation Based on Transformer with Multi-Skip Connection Decoder: Method and Evaluation in the Wild.

Heart rate is an essential vital sign to evaluate human health. Remote heart monitoring using cheaply available devices has become a necessity in the twenty-first century to prevent any unfortunate situation caused by the hectic pace of life. In this paper, we propose a new method based on the transformer architecture with a multi-skip connection biLSTM decoder to estimate heart rate remotely from videos. Our method is based on the skin color variation caused by the change in blood volume in its surface. The presented heart rate estimation framework consists of three main steps: (1) the segmentation of the facial region of interest (ROI) based on the landmarks obtained by 3DDFA; (2) the extraction of the spatial and global features; and (3) the estimation of the heart rate value from the obtained features based on the proposed method. This paper investigates which feature extractor performs better by captioning the change in skin color related to the heart rate as well as the optimal number of frames needed to achieve better accuracy. Experiments were conducted using two publicly available datasets (LGI-PPGI and Vision for Vitals) and our own in-the-wild dataset (12 videos collected by four drivers). The experiments showed that our approach achieved better results than the previously published methods, making it the new state of the art on these datasets.

Genetically Encoded Lizard Color Divergence for Camouflage and Thermoregulation.

Local adaptation is critical in speciation and evolution, yet comprehensive studies on proximate and ultimate causes of local adaptation are generally scarce. Here, we integrated field ecological experiments, genome sequencing, and genetic verification to demonstrate both driving forces and molecular mechanisms governing local adaptation of body coloration in a lizard from the Qinghai-Tibet Plateau. We found dark lizards from the cold meadow population had lower spectrum reflectance but higher melanin contents than light counterparts from the warm dune population. Additionally, the colorations of both dark and light lizards facilitated the camouflage and thermoregulation in their respective microhabitat simultaneously. More importantly, by genome resequencing analysis, we detected a novel mutation in Tyrp1 that underpinned this color adaptation. The allele frequencies at the site of SNP 459# in the gene of Tyrp1 are 22.22% G/C and 77.78% C/C in dark lizards and 100% G/G in light lizards. Model-predicted structure and catalytic activity showed that this mutation increased structure flexibility and catalytic activity in enzyme TYRP1, and thereby facilitated the generation of eumelanin in dark lizards. The function of the mutation in Tyrp1 was further verified by more melanin contents and darker coloration detected in the zebrafish injected with the genotype of Tyrp1 from dark lizards. Therefore, our study demonstrates that a novel mutation of a major melanin-generating gene underpins skin color variation co-selected by camouflage and thermoregulation in a lizard. The resulting strong selection may reinforce adaptive genetic divergence and enable the persistence of adjacent populations with distinct body coloration.

Unravelling the molecular mechanisms of skin color diversity in Africans.

Unravelling the molecular mechanisms of skin color diversity in Africans.

Integrative functional genomic analyses identify genetic variants influencing skin pigmentation in Africans.

Skin color is highly variable in Africans, yet little is known about the underlying molecular mechanism. Here we applied massively parallel reporter assays to screen 1,157 candidate variants influencing skin pigmentation in Africans and identified 165 single-nucleotide polymorphisms showing differential regulatory activities between alleles. We combine Hi-C, genome editing and melanin assays to identify regulatory elements for MFSD12, HMG20B, OCA2, MITF, LEF1, TRPS1, BLOC1S6 and CYB561A3 that impact melanin levels in vitro and modulate human skin color. We found that independent mutations in an OCA2 enhancer contribute to the evolution of human skin color diversity and detect signals of local adaptation at enhancers of MITF, LEF1 and TRPS1, which may contribute to the light skin color of Khoesan-speaking populations from Southern Africa. Additionally, we identified CYB561A3 as a novel pigmentation regulator that impacts genes involved in oxidative phosphorylation and melanogenesis. These results provide insights into the mechanisms underlying human skin color diversity and adaptive evolution.

Young Chinese female body skin pigmentation map: A pilot study.

Most studies have discussed variations in facial skin colour based on age, gender, and anatomical site within a specific ethnic group. However, skin pigmentation on the body is also a concern for many people. The aim of this study is to gather baseline data for Chinese young females, conduct a comprehensive assessment of body skin pigmentation, and create a body skin pigmentation map. Individual type angle (ITA°) was registered by CL 400 and melanin index (MI) was registered by MX 18 in 100 body points of 20 Chinese females. A total of 12,000 measurements were recorded. Our results showed significant differences among the symmetrical points on both sides of the body, including the clavicle, inner wrists, groin, inner ankle, elbow, armpit, waist side, the space between the thumb and index finger, instep, back shoulder, and popliteal space. Of all the points tested on the body, the points with the most severe skin pigmentation were the back of the neck, the heel, the elbow, and the popliteal space. This is the first comprehensive study of skin pigmentation conducted on the human body. In young Chinese women, the points with the most severe skin pigmentation were the back of the neck, heels, elbows, and the popliteal space.

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.

The MFSD12 p.Tyr182His common variant is sufficient to alter mouse agouti coat color.

MFSD12 functions as a transmembrane protein required for import of cysteine into melanosomes and lysosomes. The MFSD12 locus has been associated with phenotypic variation in skin color across African, Latin American, and East Asian populations. The frequency of a particular MFSD12 coding variant, rs2240751 (MAF = 0.08), has been reported to correlate with solar radiation and occur at highest frequency in Peruvian (PEL MAF = 0.48) and Han Chinese (CHB MAF = 0.40) populations, suggesting it could be causative for associated phenotypic variation in skin color. We have generated a mouse knock-in allele, Mfsd12Y182H , to model the human missense p.Tyr182His human variant. We demonstrate that the variant transcript is stably expressed and that agouti mice homozygote for the variant allele are viable with an altered coat color. This invivo data confirms that the MFSD12 p.Tyr182His variant functions as a hypomorphic allele sufficient to alter mammalian pigmentation.

Beautiful vulvas: expanding illustrative visual imagery of female genital cutting types.

Visual imagery has been used to educate healthcare providers, patients, and the lay public on female genital cutting (FGC) typology and reconstructive procedures. However, culturally inclusive, diverse, and anatomically accurate representation of vulvas informed by women possessing lived experience of FGC is lacking. We sought to apply World Health Organization (WHO) FGC typology to the development of type-specific visual imagery designed by a graphic artist and culturally informed by women with lived experience of FGC alongside a panel of health experts in FGC-related care. Over a 3-year process, a visual artist created watercolor renderings of vulvas with and without FGC across varying WHO types and subtypes using an iterative community-based approach. Somali women possessing lived experience of FGC were engaged alongside a team of clinician experts in FGC-related care. Women and clinicians provided descriptive input on skin color variation, texture, and skin tone, as well as the visual depiction of actions necessary in conducting a genital examination. A series of vulvar anatomic illustrations depicting WHO FGC typology. FGC types and subtypes are illustrated alongside culturally informed descriptors and clinical pearls to strengthen provider competency in the identification and documentation of FGC WHO typology, as well as facilitate patient education, counseling, shared decision making, and care. Ensuring equitable representation of race, gender, age, body type, and ability in medical illustrations may enhance patient education, counseling, and shared decision making in medical and/or surgical care. FGC provides a lens through which the incorporation of patient-informed and culturally relevant imagery and descriptors may enhance provider competency in the care of FGC-affected women and adolescents. The strengths of this study include the development of visual imagery through an iterative community-based process that engaged women with lived experience of FGC alongside clinicians with expertise in FGC-related care, as well as the representation of historically underrepresented bodies in the anatomical literature. Study limitations include the lack of generalizability to all possible forms or practices of FGC given the focus on one geographically distinct migrant community, as well as the reliance on self-report given the inability to clinically verify FGC status due to the community-based methodology employed. Patient-informed and culturally representative visual imagery of vulvas is essential to the provision of patient-centered sexual health care and education. Illustrations developed through this community-engaged work may inform future development of visual educational content that advances equity in diverse representation of medical illustrations.

Weighted correlation network analysis of the genes in the eyes of juvenile Plectropomus leopardus provide novel insights into the molecular mechanisms of the adaptation to the background color

Plectropomus leopardus is a valuable marine fish whose skin color is strongly affected by the background color. However, the influence of the visual sense on the skin color variation of P. leopardus remains unknown. In the present study, transcriptome analysis was used to examine the visual response mechanism under different background colors. Paraffin sections of the eyes showed that the background color caused morphological changes in the pigment cells (PCs) and outer nuclear layer (ONL) and the darkening of the iris color. The transcriptome analysis results indicated that the gene expressions in the eyes of P. leopardus were significantly different for different background colors. We identified 4845, 3069, 5874, and 6309 differentially expressed genes (DEGs) in the pairwise comparisons of white vs. initial, blue vs. initial, red vs. initial, and black vs. initial groups, respectively. Some hub genes and key pathways regulating the adaptive mechanism of P. leopardus's eyes to the background color were identified, i.e., the JAK-STAT, mTOR, and Ras signaling pathways, and the ndufb7, slc6a13, and novel.3553 gene. This adaptation was achieved through the synthesis of stress proteins and energy balance supply mediated by hub genes and key pathways. In addition, the phenylalanine metabolism, tyrosine metabolism, and actin cytoskeleton-related processes or pathways and genes were responsible for iris and skin color adaptation. In summary, we inferred that stress protein synthesis, phenylalanine metabolism, and energy homeostasis were critical stress pathways for P. leopardus to adapt its skin color to the environment. These new findings indicate that the P. leopardus skin color variation may have been caused by the environmental adaption of the eyes. The results provide new insights into the molecular mechanisms underlying the skin color adaptation of P. leopardus.

Seeing the Light: Lack of Skin Color Diversity Among Breastfeeding Images in an Image Bank

Seeing the Light: Lack of Skin Color Diversity Among Breastfeeding Images in an Image Bank

Human Skin Pigmentation: From a Biological Feature to a Social Determinant.

Skin pigmentation is the most variable human characteristic that can be observed and has been used throughout history to classify humans into distinct groups. Many factors influence skin colour, but the melanin pigment is considered the most important because its type and quantity can determine variations in pigmentation shades. The evolution of skin pigmentation started around 1.6-2 million years ago. As a result of migratory phenomena to places with less ultraviolet radiation (UVR) and other seasonal regimes, the selection of depigmented skin and different tanning capabilities occurred over time. Thus, genetic adaptation to new environmental conditions gradually led to changes in skin pigmentation. Despite the biological importance of pigmentation, variation in skin colour has led to social and health inequalities. Since Linnaeus, skin colour classifications have been used to describe different human groups, encouraging the misuse of a biological characteristic. This review examines the characterisation of pigmentation and its evolution through history and society. The unequal perception of pigmentation diversity has led to an incomplete state of dermatological training and issues in medical approach in dermatology. The consciousness of all these aspects increases the need to address and overcome dermatologic and social health disparities related to skin pigmentation.

The PcHY5 methylation is associated with anthocyanin biosynthesis and transport in ‘Max Red Bartlett’ and ‘Bartlett’ pears

The red coloring of pear fruits is mainly caused by anthocyanin accumulation. Red sport, represented by the green pear cultivar ‘Bartlett’ (BL) and the red-skinned derivative ‘Max Red Bartlett’ (MRB), is an ideal material for studying the molecular mechanism of anthocyanin accumulation in pear. Genetic analysis has previously revealed a quantitative trait locus (QTL) associated with red skin color in MRB. However, the key gene in the QTL and the associated regulatory mechanism remain unknown. In the present study, transcriptomic and methylomic analyses were performed using pear skin for comparisons between BL and MRB. These analyses revealed differential PcHY5 DNA methylation levels between the two cultivars; MRB had lower PcHY5 methylation than BL during fruit development, and PcHY5 was more highly expressed in MRB than in BL. These results indicated that PcHY5 is involved in the variations in skin color between BL and MRB. We further used dual luciferase assays to verify that PcHY5 activates the promoters of the anthocyanin biosynthesis and transport genes PcUFGT, PcGST, PcMYB10 and PcMYB114, confirming that PcHY5 not only regulates anthocyanin biosynthesis but also anthocyanin transport. Furthermore, we analyzed a key differentially methylated site between MRB and BL, and found that it was located in an intronic region of PcHY5. The lower methylation levels in this PcHY5 intron in MRB were associated with red fruit color during development, whereas the higher methylation levels at the same site in BL were associated with green fruit color. Based on the differential expression and methylation patterns in PcHY5 and gene functional verification, we hypothesize that PcHY5, which is regulated by methylation levels, affects anthocyanin biosynthesis and transport to cause the variations in skin color between BL and MRB.

Weighted Gene Co-Expression Network Analysis of red body color formation of crimson snapper, Lutjanus erythropterus

Crimson snapper (Lutjanus erythropterus) is a highly valued economic fish species, with its red body color being a crucial economic characteristic. A systematic study of skin pigmentation could offer insights into the mechanism of red coloration. In this study, we conducted the first network analysis of snapper transcriptomes during key developmental stages of pigmentation, identifying a cascade of cellular development and responsive gene modules and key genes, including eight developmental-specific modules. Among the four candidate hub genes (TNNT2, ROBO2, APBA2, and APOD), APOD was involved in pigmentation development. The network further revealed some key genes, such as TYRP1a, TYRP1b, PMEL, BCO1, BCO2, CYP2J2, CYP2J6, CYP3A4, PNPLA2, FABP6, ENPP7, and FFAR3, associated with melanin synthesis, carotenoids, and lipid metabolism. Our findings showed that pteridine and carotenoids were involved in yellow coloration after initial feeding, while yellow pigmentation-related genes (e.g., GCH1, PTS, SPR, CBR1, SCARB1, CD36, ABCA1, NpC1L1, etc.) had the same expression pattern at three days post-hatching (3 dph). At the red coloration emergence stage (45 dph), we observed an RNA level signal indicating the conversion of coloring substances from pteridine to carotenoids. These results substantially enhance understanding of the molecular mechanisms underlying pigmentation and skin color variation in L. erythropterus, providing a theoretical basis for improving of body coloration in economically cultured fish and genetic breeding of ornamental fish.