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Pigmentation Genes (pigmentation + gene)

Distribution by Scientific Domains

Life Sciences	37%

Selected Abstracts

Molecular variation in pigmentation genes contributing to coat colour in native Korean Hanwoo cattle

ANIMAL GENETICS, Issue 5 2008
T. R. Mohanty
Summary Pigmentation genes such as TYR (tyrosinase), TYRP1 (tyrosinase-related protein 1), DCT (previously TYRP2, or tyrosinase-related protein 2), ASIP (agouti) and MC1R (melanocortin receptor 1) play a major role in cattle coat colour. To understand the genotypic profile underlying coat colour in native Korean Hanwoo cattle and Angus black cattle, portions of the above-mentioned genes were amplified. Sequence analysis revealed variation in the TYRP1 (exon 5) and MC1R genes. Restriction enzyme analysis of these two genes could distinguish between different colours of Hanwoo cattle. Quantitative estimates of melanin and eumelanin in hair from three different-coloured Hanwoo phenotypes and Angus black showed significant differences at the breed and phenotypic levels. Finally, sequence variants in MC1R were associated with total melanin and eumelanin in breeds as well as in Hanwoo phenotypes. [source]

NATURAL SELECTION ALONG AN ENVIRONMENTAL GRADIENT: A CLASSIC CLINE IN MOUSE PIGMENTATION

EVOLUTION, Issue 7 2008
Lynne M. Mullen
We revisited a classic study of morphological variation in the oldfield mouse (Peromyscus polionotus) to estimate the strength of selection acting on pigmentation patterns and to identify the underlying genes. We measured 215 specimens collected by Francis Sumner in the 1920s from eight populations across a 155-km, environmentally variable transect from the white sands of Florida's Gulf coast to the dark, loamy soil of southeastern Alabama. Like Sumner, we found significant variation among populations: mice inhabiting coastal sand dunes had larger feet, longer tails, and lighter pigmentation than inland populations. Most striking, all seven pigmentation traits examined showed a sharp decrease in reflectance about 55 km from the coast, with most of the phenotypic change occurring over less than 10 km. The largest change in soil reflectance occurred just south of this break in pigmentation. Geographic analysis of microsatellite markers shows little interpopulation differentiation, so the abrupt change in pigmentation is not associated with recent secondary contact or reduced gene flow between adjacent populations. Using these genetic data, we estimated that the strength of selection needed to maintain the observed distribution of pigment traits ranged from 0.0004 to 21%, depending on the trait and model used. We also examined changes in allele frequency of SNPs in two pigmentation genes, Mc1r and Agouti, and show that mutations in the cis -regulatory region of Agouti may contribute to this cline in pigmentation. The concordance between environmental variation and pigmentation in the face of high levels of interpopulation gene flow strongly implies that natural selection is maintaining a steep cline in pigmentation and the genes underlying it. [source]

Genetic variants in pigmentation genes, pigmentary phenotypes, and risk of skin cancer in Caucasians

INTERNATIONAL JOURNAL OF CANCER, Issue 4 2009
Hongmei Nan
Abstract Human pigmentation is a polygenic quantitative trait with high heritability. Although a large number of single nucleotide polymorphisms (SNPs) have been identified in pigmentation genes, very few SNPs have been examined in relation to human pigmentary phenotypes and skin cancer risk. We evaluated the associations between 15 SNPs in 8 candidate pigmentation genes (TYR, TYRP1, OCA2, SLC24A5, SLC45A2, POMC, ASIP and ATRN) and both pigmentary phenotypes (hair color, skin color and tanning ability) and skin cancer risk in a nested case-control study of Caucasians within the Nurses' Health Study (NHS) among 218 melanoma cases, 285 squamous cell carcinoma (SCC) cases, 300 basal cell carcinoma (BCC) cases and 870 common controls. We found that the TYR Arg402Gln variant was significantly associated with skin color (p -value = 7.7 × 10,4) and tanning ability (p -value = 7.3 × 10,4); the SLC45A2 Phe374Leu variant was significantly associated with hair color (black to blonde) (p -value = 2.4 × 10,7), skin color (p -value = 1.1 × 10,7) and tanning ability (p -value = 2.5 × 10,4). These associations remained significant after controlling for MC1R variants. No significant associations were found between these polymorphisms and the risk of skin cancer. We observed that the TYRP1 rs1408799 and SLC45A2 1721 C>G were associated with melanoma risk (OR, 0.77; 95% CI, 0.60,0.98 and OR, 0.75; 95% CI, 0.60,0.95, respectively). The TYR Ser192Tyr was associated with SCC risk (OR, 1.23; 95% CI, 1.00,1.50). The TYR haplotype carrying only the Arg402Gln variant allele was significantly associated with SCC risk (OR, 1.35; 95% CI, 1.04,1.74). The OCA2 Arg419Gln and ASIP g.8818 A>G were associated with BCC risk (OR, 1.50; 95% CI, 1.06,2.13 and OR, 0.73; 95% CI, 0.53,1.00, respectively). The haplotype near ASIP (rs4911414[T] and rs1015362[G]) was significantly associated with fair skin color (OR, 2.28; 95% CI, 1.46,3.57) as well as the risks of melanoma (OR, 1.68; 95% CI, 1.18,2.39) and SCC (OR, 1.54; 95% CI, 1.08,2.19). These associations remained similar after adjusting for pigmentary phenotypes and MC1R variants. The statistical power of our study was modest and additional studies are warranted to confirm the associations observed in the present study. Our study provides evidence for the contribution of pigmentation genetic variants, in addition to the MC1R variants, to variation in human pigmentary phenotypes and possibly the development of skin cancer. © 2009 UICC [source]

The evolution of teleost pigmentation and the fish-specific genome duplication

JOURNAL OF FISH BIOLOGY, Issue 8 2008
I. Braasch
Teleost fishes have evolved a unique complexity and diversity of pigmentation and colour patterning that is unmatched among vertebrates. Teleost colouration is mediated by five different major types of neural-crest derived pigment cells, while tetrapods have a smaller repertoire of such chromatophores. The genetic basis of teleost colouration has been mainly uncovered by the cloning of pigmentation genes in mutants of zebrafish Danio rerio and medaka Oryzias latipes. Many of these teleost pigmentation genes were already known as key players in mammalian pigmentation, suggesting partial conservation of the corresponding developmental programme among vertebrates. Strikingly, teleost fishes have additional copies of many pigmentation genes compared with tetrapods, mainly as a result of a whole-genome duplication that occurred 320,350 million years ago at the base of the teleost lineage, the so-called fish-specific genome duplication. Furthermore, teleosts have retained several duplicated pigmentation genes from earlier rounds of genome duplication in the vertebrate lineage, which were lost in other vertebrate groups. It was hypothesized that divergent evolution of such duplicated genes may have played an important role in pigmentation diversity and complexity in teleost fishes, which therefore not only provide important insights into the evolution of the vertebrate pigmentary system but also allow us to study the significance of genome duplications for vertebrate biodiversity. [source]