Skin Color Variation Research Articles

Developmental transitions in body color in chacma baboon infants: Implications to estimate age and developmental pace

In many primates, one of the most noticeable morphological developmental traits is the transition from natal fur and skin color to adult coloration. Studying the chronology and average age at such color transitions can be an easy and noninvasive method to (a) estimate the age of infants whose dates of birth were not observed, and (b) detect interindividual differences in the pace of development for infants with known birth dates. Using a combination of photographs and field observations from 73 infant chacma baboons (Papio ursinus) of known ages, we (a) scored the skin color of six different body parts from pink to gray, as well as the color of the fur from black to gray; (b) validated our method of age estimation using photographic and field observations on an independent subset of 22 infants with known date of birth; and (c) investigated ecological, social, and individual determinants of age-related variation in skin and fur color. Our results show that transitions in skin color can be used to age infant chacma baboons less than 7 months old with accuracy (median number of days between actual and estimated age = 10, range = 0-86). We also reveal that food availability during the mother's pregnancy, but not during lactation, affects infant color-for-age and therefore acts as a predictor of developmental pace. This study highlights the potential of monitoring within- and between-infant variation in color to estimate age when age is unknown, and developmental pace when age is known.

Comparative phytochemical analysis of the fruits of four Florida-grown finger lime (Citrus australasica) selections

Finger lime (Citrus australasica F. Muell.), a citrus species native to Australia, is a distinct finger-shaped fruit with unique caviar-like pulp and skin color variations. In addition to visual and sensory characteristics, finger lime has recently gained attention from the American citrus industry due to its tolerance to a devastating citrus disease, Huanglongbing (HLB). Here, we characterized the phytochemical profiles (including acid and sugar) of four Florida-grown finger lime selections: two with red pulp, one with pale pink pulp, and one with white pulp. Two-three-fold higher levels of phenolic compounds and antioxidant capacity were observed in the peel compared to the pulp in the four selections. Selections with red pulp had more antioxidant capacity and higher phenolic compound content in both types of tissues than in the selections with white pulp. Citric acid was found abundant in all four selections making the selections a major source of organic acid. The overall results suggested that finger limes are rich in health-benefiting and flavor contributing compounds; more specifically, Florida-grown red selections of finger lime are richest in phytochemicals, vitamin c, citric acid, and sugars among evaluated genotypes, therefore, making them strong alternative for production in Florida and consumption.

Emerging role of dermal compartment in skin pigmentation: comprehensive review.

The variations in human skin colour mainly occur due to differences in the distribution of melanin pigment throughout the body, synthesized by epidermal melanocytes which are further taken up by keratinocytes present in epidermis. Recently, it has been discovered that besides these cells, dermis derived fibroblast factors also play a prominent role in regulating skin pigmentation. There exists a signal crosstalk between epidermal melanocytes, keratinocytes and dermal fibroblasts and any impairment in these signalling pathways may give rise to pigmentary disorders. Vitiligo is a hypopigmentary disorder and alteration in the expression level of several fibroblast-specific factors has been reported in the lesional skin of vitiligo patients. In such patients, there is decrease in the expression levels of factors such as basic fibroblast growth factor, stem cell factor (SCF) and keratinocyte growth factor (KGF) along with a steep increase in the expression levels of Dickkopf 1. Patients affected with hyperpigmentary disorder like melasma exhibit a marked increase in SCF and KGF expression levels leading to increase in melanin production and those affected with solar lentigo experience upregulation in the expression levels of SCF, KGF and HGF (hepatocyte growth factor). Hence, we conclude that new therapeutic strategies can be adopted to cure these pigmentary disorders by targeting factors involved in crosstalk signalling between epidermal melanocytes, keratinocytes and dermal fibroblasts.

Skin pigmentation and genetic variants in an admixed Brazilian population of primarily European ancestry.

Although many genes have been shown to be associated with human pigmentary traits and forensic prediction assays exist (e.g. HIrisPlex-S), the genetic knowledge about skin colour remains incomplete. The highly admixed Brazilian population is an interesting study population for investigation of the complex genotype-phenotype architecture of human skin colour because of its large variation. Here, we compared variants in 22 pigmentary genes with quantitative skin pigmentation levels on the buttock, arm, and forehead areas of 266 genetically admixed Brazilian individuals. The genetic ancestry of each individual was estimated by typing 46 AIM-InDels. The mean proportion of genetic ancestry was 68.8% European, 20.8% Sub-Saharan African, and 10.4% Native American. A high correlation (adjusted R2 = 0.65, p < 0.05) was observed between nine SNPs and quantitative skin pigmentation using multiple linear regression analysis. The correlations were notably smaller between skin pigmentation and biogeographic ancestry (adjusted R2 = 0.45, p < 0.05), or markers in the leading forensic skin colour prediction system, the HIrisPlex-S (adjusted R2 = 0.54, p < 0.05). Four of the nine SNPs, OCA2 rs1448484 (rank 2), APBA2 rs4424881 (rank 4), MFSD12 rs10424065 (rank 8), and TYRP1 1408799 (rank 9) were not investigated as part of the HIrisPlex-S selection process, and therefore not included in the HIrisPlex-S model. Our results indicate that these SNPs account for a substantial part of the skin colour variation in individuals of admixed ancestry. Hence, we suggest that these SNPs are considered when developing future skin colour prediction models.

Examination of the Physiological Status of the Human Cardiovascular System In Vivo Through Skin Color Variations

Examination of the Physiological Status of the Human Cardiovascular System In Vivo Through Skin Color Variations

Effects of photoperiod on growth performance and melanogenesis pathway for skin pigmentation of Malaysian red tilapia

Farming of red tilapia is increasing rapidly. However, its commercial farming development is challenged by lack of clear information on genetic basis for skin colour and pigmentation differences due to environmental changes. This study investigated the effects of photoperiod (light:dark, L:D) on the growth and skin colour variation of Malaysian red tilapia. A total of 180 fish weighing 150.48 ± 0.44 g were reared under natural photoperiod (13L:11D, control), prolonged lightness (24L:0D) and prolonged darkness (0L:24D) in three replicates for 78 days. The weight gain of fish cultured under both prolonged light and darkness were significantly higher than fish under natural photoperiod. The tyrosinase level in ventral skin was significantly higher for fish cultured under prolonged darkness condition than in the other two photoperiod regimes. Contrary, the cysteine level in the dorsal skin was significantly higher in the fish cultured under natural photoperiod than in prolonged light and darkness. The relative mRNA expressions of SRY‐related HMG‐Box 10 (sox 10), tyrosine (tyr), tyrosine‐related protein 1 (tyrp‐1) and solute carrier family 7 member 11 (slc7a11) genes were significantly higher in ventral skin of fish under prolonged darkness than the other two photoperiods. This study demonstrates that photoperiod has an impact on melanogenesis and growth of red tilapia. Understanding the effects of photoperiod on genetic basis of red tilapia will help in selective breeding programme of the important economic traits for the development of commercial red tilapia farming.

Enhanced Self-Perception in Mixed Reality: Egocentric Arm Segmentation and Database With Automatic Labeling

In this study, we focus on the egocentric segmentation of arms to improve self-perception in Augmented Virtuality (AV). The main contributions of this work are: i) a comprehensive survey of segmentation algorithms for AV; ii) an Egocentric Arm Segmentation Dataset (EgoArm), composed of more than 10, 000 images, demographically inclusive (variations of skin color, and gender), and open for research purposes. We also provide all details required for the automated generation of groundtruth and semi-synthetic images; iii) the proposal of a deep learning network to segment arms in AV; iv) a detailed quantitative and qualitative evaluation to showcase the usefulness of the deep network and EgoArm dataset, reporting results on different real egocentric hand datasets, including GTEA Gaze+, EDSH, EgoHands, Ego Youtube Hands, THU-Read, TEgO, FPAB, and Ego Gesture, which allow for direct comparisons with existing approaches using color or depth. Results confirm the suitability of the EgoArm dataset for this task, achieving improvements up to 40% with respect to the baseline network, depending on the particular dataset. Results also suggest that, while approaches based on color or depth can work under controlled conditions (lack of occlusion, uniform lighting, only objects of interest in the near range, controlled background, etc.), deep learning is more robust in real AV applications.

The Noninvasive Blood Pressure Measurement Based on Facial Images Processing

This paper proposes a noninvasive method of physiological parameter measurement with the collected facial video images for continuous online monitoring. Blood pressure (BP) is one of the important physiological indexes for human health prognoses. Based on the photoplethysmograph (PPG) technology, the variation of the facial skin color along with the heart beating can thus be captured via the camera. So the related BP information can be extracted from the blind source signal separation. The detailed procedure of the BP measurement from the facial video is explained, including video collection, face tracking, signal pre-processing, and BP signal extraction. The systolic and diastolic BP model can be derived based on the radial resonance theory and the involved parameters are fitted via the sampling data. Experiments are performed in different scenarios to discuss the impact factors on the BP detection together with error compensation analysis. The experimental results demonstrate that the proposed BP online measurement can be used as an indicator to monitor the status of the human health continuously.

Skin Balancing: Skin Color-Based Calibration for Portrait Images to Enhance the Affective Quality

Because our sensitivity to human skin color leads to a precise chromatic adjustment, skin color has been considered a calibration target to enhance the quality of images that contain human faces. In this paper, we investigated the perceived quality of portrait images depending on how the target skin color is defined: measured, memory, digital, or CCT skin color variations. A user study was conducted; 24 participants assessed the quality of white-balanced portraits on five criteria: reality, naturalness, appropriateness, preference, and emotional enhancement. The results showed that the calibration using measured skin color best served the aspects of reality and naturalness. With regard to appropriateness and preference, digital skin color obtained the highest score. Also, the memory skin color was appropriate to calibrate portraits with emotional enhancement. In addition, the other two CCT target colors enhanced the affective quality of portrait images, but the effect was quite marginal. In the foregoing, labelled Skin Balance, this study proposes a set of alternative targets for skin color, a simple but efficient way of reproducing portrait images with affective enhancement.

Platyrrhine color signals: New horizons to pursue.

Like catarrhines, some platyrrhines show exposed and reddish skin, raising the possibility that reddish signals have evolved convergently. This variation in skin exposure and color combined with sex‐linked polymorphic color vision in platyrrhines presents a unique, and yet underexplored, opportunity to investigate the relative importance of chromatic versus achromatic signals, the influence of color perception on signal evolution, and to understand primate communication broadly. By coding the facial skin exposure and color of 96 platyrrhines, 28 catarrhines, 7 strepsirrhines, 1 tarsiiform, and 13 nonprimates, and by simulating the ancestral character states for these traits, we provide the first analysis of the distribution and evolution of facial skin exposure and color in platyrrhini. We highlight ways in which studying the presence and use of color signals by platyrrhines and other primates will enhance our understanding of the evolution of color signals, and the forces shaping color vision.

The Evolutionary History of Human Skin Pigmentation.

Skin pigmentation is a complex, conspicuous, highly variable human trait that exhibits a remarkable correlation with latitude. The evolutionary history and genetic basis of skin color variation has been the subject of intense research in the last years. This article reviews the major hypotheses explaining skin color diversity and explores the implications of recent findings about the genes associated with skin pigmentation for understanding the evolutionary forces that have shaped the current patterns of skin color variation. A major aspect of these findings is that the genetic basis of skin color is less simple than previously thought and that geographic variation in skin pigmentation was influenced by the concerted action of different types of natural selection, rather than just by selective sweeps in a few key genes.

Contactless approach for heart rate estimation for QoE assessment

Quality of Experience of multimedia content is investigated to understand the overall acceptability of the content as perceived by the end user. Recent perspectives stress the need to focus not only on perceptual aspects of the content but also on the interaction between perception and cognitive–emotional aspects. Our contribution lies on this direction by presenting a contactless approach to estimate heart rate variability by evaluating face skin color variations in a video sequence. The proposed framework allows to analyze long video sequences depicting a subject and it is robust with respect to small movements and illumination changes. The system is validated on a dataset of 64 sequences where users observe 3D movies selected to induce heart rate variations.

Characterization and functional analysis of slc7a11 gene, involved in skin color differentiation in the red tilapia

Red tilapia has become more popular for aquaculture production in China in recent years. However, the pigmentation differentiation that has resulted from the process of genetic breeding and skin color variation during the overwintering period are the main problems limiting the development of commercial culture. The genetic basis of skin color differentiation is still not understood. Solute carrier family 7 member 11 (slc7a11) has been identified to be a critical genetic regulator of pheomelanin synthesis in the skin of mammals. However, little information is available about its molecular characteristics, expression, location and function in skin color differentiation of fish. In this study, three complete cDNA sequences (2159 bp, 2190 bp and 2249 bp) of slc7a11 were successfully isolated from Malaysian red tilapia, encoding polypeptides of 492, 525 and 492 amino acids respectively. Quantitative real-time PCR demonstrated that slc7a11 mRNA expression is high in the ventral skin of PR (pink with scattered red spots) fish. Immunofluorescence analysis revealed that xCT (the protein encoded by slc7a11) was concentrated mainly in the cytoplasm and nucleus of both the dorsal and ventral skin cells of fish. After RNA interference of slc7a11, slc7a11 and cbs mRNA expressions decreased, but the tyr mRNA expression increased in the skin of fish. Results suggest that slc7a11 plays an important role in skin color formation and differentiation of red tilapia through the melanogenesis pathway.

AAPA Statement on Race and Racism.

AAPA Statement on Race and Racism.

How well do we understand the basis of classic selective sweeps in humans?

Classic selective sweeps occur when positive selection increases a variant's frequency from low to high in a population, and underlie some long-studied human characteristics such as variation in skin, hair or eye colour. In such well-studied 'gold standard' examples, a known variant has been associated with a plausible phenotype and underlying selective force. Signatures of classic sweeps have more recently been detected in population-genetic data independently of any prior information about the corresponding phenotype or selective force, and usually without suggesting any insights into these. Motivated by the need to understand such candidates, we first review the gold standards and show that our understanding of them is often incomplete or unconvincing; only two of the examples we consider are compellingly explained. We assess approaches for large-scale association of classic sweep candidate variants to phenotypes and selective forces, test these on the gold standards, and discuss the standards of evidence needed to adequately understand a selective sweep.

The color continuum: Skin tone and online dating preferences among Asian Americans

Despite the increasing body of literature surrounding online dating preferences, there remains a paucity of research that analyzes whether skin color influences the dating selection process. To fill this empirical gap, the present study uses data collected from 2,024 Asian dating profiles, including the skin tone of the daters, to assess the impact that skin color variation may have on the inter- and intraracial dating preferences of heterosexual males and females as well as gay males and lesbians. This research also examines whether skin tone has a pronounced effect on the relationship between sexual orientation and the willingness to date Asians, African Americans, and Latino/Latinas. The current findings suggest that darker skinned Asians are more likely to state a preference to date African Americans and Latino/Latinas compared to their lighter skinned counterparts; however, they are less willing to date another Asian. The results also document significant interaction effects between sexual orientation and skin color differences. Our findings are discussed in relation to the racial hierarchy of preference and privilege that are inherently linked to the longstanding concept of colorism.

Skin color variation: A study on Eastern and North East India

Background: Skin pigmentation is one of the most variable phenotypic traits and most noticeable of human polymorphisms. Skin pigmentation in humans is largely determined by the quantity and distribution of the pigment melanin. The literature review on skin color variation revealed a few works on skin pigmentation variation has been conducted in India from Southern, Western and Northern part.&#x0D; Aims and Objectives: To best of the knowledge, the present discourse is the first attempt to understand skin color variation from Eastern and North Eastern part of India among three populations.&#x0D; Materials and Methods: The present study consisted of 312 participants from Chakma and Tripuri groups of Tripura, North East India, and participants from Bengalee Hindu caste population from West Bengal. Skin color was measured by Konica Minolta CR-10 spectrophotometer which measures and quantifies the colors with a 3D color space (CIELAB) color space created by 3 axes. All the skin color measurements from each participant were taken from unexposed (underarm) left and right to get a mean and exposed (forehead) to sunlight.&#x0D; Results: The distribution of skin color variation among the three populations demonstrated significant (p&lt;0.05) difference in lightness for unexposed and exposed indicating lightness in unexposed area. Furthermore, the present study revealed significant difference (p&lt;0.05) in skin color among the ethnic groups across the body location and all three attributes (lightness, redness and yellowness).&#x0D; Conclusion: Generally, skin color variation may be elucidated by two main factors: individual differences in lightness and yellowness and by and large due to ethnicity, where diversity in redness is due to primarily due to different body locations. Variation in lightness have more characteristic probability. The present study first time reports the wide range of quantitative skin color variation among the three ethnic groups from Eastern and North East India and highest yellowness (b*) among the population from North East India.

To See or Not to See: Issues Surrounding the Social Meanings of Skin Color

Skin color, one of the most conspicuous physical traits, encompasses complex social and cultural meanings and value judgments that can influence individuals’ lived experiences and social wellbeing in a profound way. In this article, the authors provide a brief overview of how skin color diversity evolved, its corresponding biological and sociocultural aspects, and how culturally constructed ideologies and perceptions of skin color may influence social interactions. They illustrate the importance of examining historical fallacies as a means to better understand the ramifications of skin color and argue that cultivating a clearer picture of issues underlying meanings of skin color in higher education will help to dispel misconceptions and prepare students and society to thrive in an increasingly diverse environment.

Outcomes of paramedian forehead flap for reconstruction of large nasal defects: Menoufia experience

Objective The aim of this case series study was to evaluate outcomes of paramedian forehead flap in reconstruction of large nasal defects. Background Nasal reconstruction is a challenging pursuit owing to its complex three-dimensional structure; the different components of skin, bone, cartilage, and mucosal lining; and the variations in skin thickness and color of the nose. This study describes forehead flap technique for reconstruction of large nasal defects more than 2 cm after excision of a neoplasm. Patients and methods From January 2012 to December 2015, 14 patients who had large nasal defects received surgical treatment in the form of either expanded paramedian forehead flap (group A, n = 5 patients) or nonexpanded paramedian forehead flap (group B, n = 9 patients). Demographic data, nasal defect characteristics, postoperative complications (infection, wound dehiscence, and flap necrosis), comparison between two groups of patients, and doctor and patient satisfaction were recorded. Results The overall results were satisfactory regarding function and appearance without major complications according to patient and doctor satisfaction. Wound dehiscence occurred in one (7.14%) case and healed with conservative treatment. Another patient (7.14%) was complicated with infection at the site of expander port and was treated with antibiotics. Conclusion The forehead flap continues to be one of the best options for closure of surgical defects of the nose larger than 3 cm. Adequate knowledge and careful application of the technique and its modifications allows excellent results to be obtained with few complications.

The Genetics of Skin Color Variation in Farm Animals

The Genetics of Skin Color Variation in Farm Animals