Search results for "Hair Color"

Fifteen Shades of Grey: Combined Analysis of Genome-Wide SNP Data in Steppe and Mediterranean Grey Cattle Sheds New Light on the Molecular Basis of C…

2020

Coat color is among the most distinctive phenotypes in cattle. Worldwide, several breeds share peculiar coat color features such as the presence of a fawn pigmentation of the calf at birth, turning over time to grey, and sexual dichromatism. The aim of this study was to search for polymorphisms under differential selection by contrasting grey cattle breeds displaying the above phenotype with non-grey cattle breeds, and to identify the underlying genes. Using medium-density SNP array genotype data, a multi-cohort FST-outlier approach was adopted for a total of 60 pair-wise comparisons of the 15 grey with 4 non-grey cattle breeds (Angus, Limousin, Charolais, and Holstein), with the latter sel…

Genome-wide analyses reveal the regions involved in the phenotypic diversity in Sicilian pigs.

2019

Nero Siciliano (Sicilian Black, SB) is a local pig breed generally of uniform black color. In addition to this officially recognized breed, there are animals showing morphological characteristics resembling the SB but with gray hair (Sicilian Grey, SG). The SG, compared with the SB, also shows a more compact structure with greater transverse diameters, higher average daily gains and lower thickness of the back fat. In this study, using the Illumina PorcineSNP60 BeadChip, we run genome-wide analyses to identify regions that may explain the phenotypic differences between SB (n = 21) and SG (n = 27) individuals. Combining the results of the two case–control approaches (GWAS and FST), we identi…

Genetic 3’UTR variation is associated with human pigmentation characteristics and sensitivity to sunlight

2017

Sunlight exposure induces signalling pathways leading to the activation of melanin synthesis and tanning response. MicroRNAs (miRNAs) can regulate the expression of genes involved in pigmentation pathways by binding to the complementary sequence in their 3'untranslated regions (3'UTRs). Therefore, 3'UTR SNPs are predicted to modify the ability of miRNAs to target genes, resulting in differential gene expression. In this study, we investigated the role in pigmentation and sun-sensitivity traits, as well as in melanoma susceptibility, of 38 different 3'UTR SNPs from 38 pigmentation-related genes. A total of 869 individuals of Spanish origin (526 melanoma cases and 343 controls) were analysed.…

Influence of Pigmentation on the Codeine Content of Hair Fibers in Guinea Pigs

1997

Tortoise shell guinea pigs (n = 7) were administered codeine (1 mg/mL codeine-base) in their drinking water for 3 weeks. Black, reddish-brown and white hair was collected separately from each animal before and after treatment. The hair samples were analyzed by GC/MS. The experiment showed positive results for all hair fibers with large individual variability of drug incorporation. Low drug intake resulted in small differences of the drug content in hair fibers different in color, whereas in cases of high drug intake a strong influence of hair pigmentation on the analytical results was observed. The highest drug content was always found in black hair samples, non-pigmented hair showed the lo…

Direct evidence for positive selection of skin, hair, and eye pigmentation in Europeans during the last 5,000 y

2014

Significance Eye, hair, and skin pigmentation are highly variable in humans, particularly in western Eurasian populations. This diversity may be explained by population history, the relaxation of selection pressures, or positive selection. To investigate whether positive natural selection is responsible for depigmentation within Europe, we estimated the strength of selection acting on three genes known to have significant effects on human pigmentation. In a direct approach, these estimates were made using ancient DNA from prehistoric Europeans and computer simulations. This allowed us to determine selection coefficients for a precisely bounded period in the deep past. Our results indicate t…

Sex and MC1R variants in human pigmentation: Differences in tanning ability and sensitivity to sunlight between sexes

2016

A comparison of 3 H-cocaine binding on melanin granules and human hair in vitro

1997

The in vitro experiments on the interaction of 3H-cocaine and melanin from Sepia officinalis confirmed the existence of drug binding sites on melanin granules. The results suggested that the binding of 3H-cocaine to melanin could be analyzed by assuming that the binding to the surface of pigment granules is analogous to the adsorption of a drug on a solid and follows Langmuir adsorption isotherm type I. Scatchard analysis indicated heterogeneity of binding sites. Structural and chemical alterations caused by isolation of the melanoproteins, which are heterogeneous in nature and show different physico-chemical properties, are considered to be most crucial. The studies on hair samples confirm…

Missense and nonsense mutations in melanocortin 1 receptor (MC1R) gene of different goat breeds: association with red and black coat colour phenotype…

2009

Abstract Background Agouti and Extension loci control the relative amount of eumelanin and pheomelanin production in melanocytes that, in turn, affects pigmentation of skin and hair. The Extension locus encodes the melanocortin 1 receptor (MC1R) whose permanent activation, caused by functional mutations, results in black coat colour, whereas other inactivating mutations cause red coat colour in different mammals. Results The whole coding region of the MC1R gene was sequenced in goats of six different breeds showing different coat colours (Girgentana, white cream with usually small red spots in the face; Maltese, white with black cheeks and ears; Derivata di Siria, solid red; Murciano-Granad…

Pharmacological Characterization of Loss of Function Mutations of the Human Melanocortin 1 Receptor That Are Associated with Red Hair

2004

Variation in skin color is the major host risk factor for melanoma and other forms of skin cancer. Individuals with red hair show an increased ratio of phaeomelanin to eumelanin in both hair and skin. This ratio is regulated by the melanocortin (MC) 1 receptor. There are several common point mutations in the human MC1 receptor that are overrepresented in North European red-heads, and in individuals with pale skin. In order to determine the functional significance of these mutations, we expressed the Asp84Glu, Val92Met, Arg163Gln, and Asp294His variants of the human MC1 receptors in eukaryotic cells and determined their ability to bind alpha-melanocyte stimulating hormone (MSH) peptides and …