Comparative skin transcriptome of two Oujiang color common carp (Cyprinus carpio var. color) varieties.

Body color variation has long been a hot research topic in evolutionary and functional biology. Oujiang color common carp (Cyprinus carpio var. color) is a well-known economical and ornamental fish. Three main types of pigments and four distinct color patterns are typical characters of Oujiang color common carp, which makes it an excellent fish model to study body coloration. In this study, skin transcriptome assembly and comparisons were conducted in two Oujiang color common carp varieties: whole red and whole white. Transcriptome comparison revealed that more differentially expressed energy metabolism genes were upregulated in whole white compared to whole red. The results indicated that energy metabolism genes might be strongly associated with environmental adaption and growth performance and likely affect the red and white color formation in Oujiang color common carp. Our study provided direct guidance for the aquaculture industrials of Oujiang color common carp and presented valuable genetic resources for body color research in fish.

A Genetic Mechanism for Convergent Skin Lightening during Recent Human Evolution.

Skin lightening among Eurasians is thought to have been a convergence occurring independently in Europe and East Asia as an adaptation to high latitude environments. Among Europeans, several genes responsible for such lightening have been found, but the information available for East Asians is much more limited. Here, a genome-wide comparison between dark-skinned Africans and Austro-Asiatic speaking aborigines and light-skinned northern Han Chinese identified the pigmentation gene OCA2, showing unusually deep allelic divergence between these groups. An amino acid substitution (His615Arg) of OCA2 prevalent in most East Asian populations-but absent in Africans and Europeans-was significantly associated with skin lightening among northern Han Chinese. Further transgenic and targeted gene modification analyses of zebrafish and mouse both exhibited the phenotypic effect of the OCA2 variant manifesting decreased melanin production. These results indicate that OCA2 plays an important role in the convergent skin lightening of East Asians during recent human evolution.

Identification of pigmentation genes in skin, muscle and tail of a Thai-flag variety of Siamese fighting fish Betta splendens.

Pigmentation genes expressed in skin, body muscle and tail of Thai-flag compared with Blue, White and Red varieties of Siamese fighting fish Betta splendens were identified. In total, 22,919 new unigenes were found. Pearson correlation and PCA analysis revealed that expression profiles of genes in muscle, skin and tail across solid color variety were similar. In contrast, those in skin and red tail part of Thai-flag were closely related but they showed different expression profiles with the white tail part. Moreover, 21,347-64,965 SNPs were identified in exonic regions of identified genes. In total, 28,899 genes were differentially expressed between paired comparisons of libraries where 13,907 genes (48.12 %) were upregulated and 14,992 genes (51.88 %) were downregulated. DEGs between paired libraries were 106-5775 genes relative to the compared libraries (56-2982 and 50-2782 for upregulated and downregulated DEGs). Interestingly, 432 pigmentation genes of B. splendens were found. Of these, 297 DEGs showed differential expression between varieties. Many DEGs in melanogenesis (Bsmcr1r, Bsmcr5r, and Bsslc2a15b), tyrosine metabolism (Bstyr, Bstyrp1b and Bsdct), stripe repressor (BsAsip1 and BsAsip2b), pteridine (Bsgch2) and carotenoid (BsBco2) biosynthesis were downregulated in the Thai-flag compared with solid color varieties. Expression of Bsbco1l, Bsfrem2b, Bskcnj13, Bszic2a and Bspah in skin, muscle and tail of Thai-flag, Blue, Red and White varieties was analyzed by qRT-PCR and revealed differential expression between fish varieties and showed anatomical tissue-preferred expression patterns in the same fish variety. The information could be applied to assist genetic-based development of new B. splendens varieties in the future.

Candidate pigmentation genes related to feather color variation in an indigenous chicken breed revealed by whole genome data.

Chicken plumage color is an inheritable phenotype that was naturally and artificially selected for during domestication. The Baicheng You chicken is an indigenous Chinese chicken breed presenting three main feather colors, lavender, black, and yellow plumages. To explore the genetic mechanisms underlying the pigmentation in Baicheng You chickens, we re-sequenced the whole genome of Baicheng You chicken with the three plumage colors. By analyzing the divergent regions of the genome among the chickens with different feather colors, we identified some candidate genomic regions associated with the feather colors in Baicheng You chickens. We found that EGR1, MLPH, RAB17, SOX5, and GRM5 genes were the potential genes for black, lavender, and yellow feathers. MLPH, GRM5, and SOX5 genes have been found to be related to plumage colors in birds. Our results showed that EGR1 is a most plausible candidate gene for black plumage, RAB17, MLPH, and SOX5 for lavender plumage, and GRM5 for yellow plumage in Baicheng You chicken.

The modular expression patterns of three pigmentation genes prefigure unique abdominal morphologies seen among three Drosophila species.

To understand how novel animal body colorations emerged, one needs to ask how the development of color patterns differs among closely related species. Here we examine three species of fruit flies - Drosophila guttifera (D. guttifera), D. palustris, and D. subpalustris - displaying a varying number of abdominal spot rows. Through in situ hybridization experiments, we examine the mRNA expression patterns for the pigmentation genes Dopa decarboxylase (Ddc), tan (t), and yellow (y) during pupal development. Our results show that Ddc, t, and y are co-expressed in modular, identical patterns, each foreshadowing the adult abdominal spots in D. guttifera, D. palustris, and D. subpalustris. We suggest that differences in the expression patterns of these three genes partially underlie the morphological diversity of the quinaria species group.

GBS Data Identify Pigmentation-Specific Genes of Potential Role in Skin-Photosensitization in Two Tunisian Sheep Breeds.

The Tunisian Noire de Thibar sheep breed is a composite breed, recently selected to create animals that are uniformly black in order to avoid skin photosensitization after the ingestion of toxic "hypericum perforatum" weeds, which causes a major economic loss to sheep farmers. We assessed genetic differentiation and estimated marker FST using genotyping-by-sequencing (GBS) data in black (Noire de Thibar) and related white-coated (Queue fine de l'ouest) sheep breeds to identify signals of artificial selection. The results revealed the selection signatures within candidate genes related to coat color, which are assumed to be indirectly involved in the mechanism of photosensitization in sheep. The identified genes could provide important information for molecular breeding.

Whole Genome Sequencing of the Asian Arowana (Scleropages formosus) Provides Insights into the Evolution of Ray-Finned Fishes.

The Asian arowana (Scleropages formosus) is of commercial importance, conservation concern, and is a representative of one of the oldest lineages of ray-finned fish, the Osteoglossomorpha. To add to genomic knowledge of this species and the evolution of teleosts, the genome of a Malaysian specimen of arowana was sequenced. A draft genome is presented consisting of 42,110 scaffolds with a total size of 708 Mb (2.85% gaps) representing 93.95% of core eukaryotic genes. Using a k-mer-based method, a genome size of 900 Mb was also estimated. We present an update on the phylogenomics of fishes based on a total of 27 species (23 fish species and 4 tetrapods) using 177 orthologous proteins (71,360 amino acid sites), which supports established relationships except that arowana is placed as the sister lineage to all teleost clades (Bayesian posterior probability 1.00, bootstrap replicate 93%), that evolved after the teleost genome duplication event rather than the eels (Elopomorpha). Evolutionary rates are highly heterogeneous across the tree with fishes represented by both slowly and rapidly evolving lineages. A total of 94 putative pigment genes were identified, providing the impetus for development of molecular markers associated with the spectacular colored phenotypes found within this species.

The genetics of skin, hair, and eye color variation and its relevance to forensic pigmentation predictive tests.

This review examines the potential application of single nucleotide polymorphism (SNP)-based predictive tests for skin, hair, and eye color to forensic analysis in support of police investigations lacking DNA database matches or eyewitness testimony. Brief descriptions of the biology of melanogenesis and the main genes involved are presented in order to understand the basis of common pigmentation variation in humans. We outline the most recently developed forensically sensitive multiplex tests that can be applied to investigative analyses. The review also describes the biology of the SNPs with the closest associations to, and therefore the best predictors for, common variation in eye, hair, and skin pigmentation. Because pigmentation pathways are complex in their patterns, many of the better-studied human albinism traits provide insight into how pigmentation SNPs interact, control, or modify gene expression and show varying degrees of association with the key genes identified to date. These aspects of SNP action are discussed in an overview of each of the functional groups of pigmentation genes.

SLC24A5 and ASIP as phenotypic predictors in Brazilian population for forensic purposes.

Pigmentation is a variable and complex trait in humans and it is determined by the interaction of environmental factors, age, disease, hormones, exposure to ultraviolet radiation and genetic factors, including pigmentation genes. Many polymorphisms of these genes have been associated with phenotypic diversity of skin, eyes and hair color in homogeneous populations. Phenotype prediction from biological samples using genetic information has benefited forensic area in some countries, leading some criminal investigations. Herein, we evaluated the association between polymorphisms in the genes SLC24A5 (rs1426654) and ASIP (rs6058017) with skin, eyes and hair colors, in 483 healthy individuals from Brazilian population for attainable use in forensic practice. The volunteers answered a questionnaire where they self-reported their skin, eye and hair colors. The polymorphic homozygous genotype of rs1426654∗A and rs6058017∗A in SLC24A5 and ASIP respectively, showed strongest association with fairer skin (OR 47.8; CI 14.1-161.6 and OR 8.6; CI 2.5-29.8); SLC24A5 alone showed associations with blue eyes (OR 20.7; CI 1.2-346.3) and blond hair (OR 26.6; CI 1.5-460.9). Our data showed that polymorphic genotypes (AA), in both genes, are correlated with characteristics of light pigmentation, while the ancestral genotype (GG) is related to darker traits, corroborating with previous studies in European and African populations. These associations show that specific molecular information of an individual may be useful to access some phenotypic features in an attempt to help forensic investigations, not only on crime scene samples but also in cases of face reconstructions in unknown bodies.

Sequence variation in the melanocortin-1 receptor (MC1R) pigmentation gene and its role in the cryptic coloration of two South American sand lizards.

In reptiles, dorsal body darkness often varies with substrate color or temperature environment, and is generally presumed to be an adaptation for crypsis or thermoregulation. However, the genetic basis of pigmentation is poorly known in this group. In this study we analyzed the coding region of the melanocortin-1-receptor (MC1R) gene, and therefore its role underlying the dorsal color variation in two sympatric species of sand lizards (Liolaemus) that inhabit the southeastern coast of South America: L. occipitalis and L. arambarensis. The first is light-colored and occupies aeolic pale sand dunes, while the second is brownish and lives in a darker sandy habitat. We sequenced 630 base pairs of MC1R in both species. In total, 12 nucleotide polymorphisms were observed, and four amino acid replacement sites, but none of them could be associated with a color pattern. Comparative analysis indicated that these taxa are monomorphic for amino acid sites that were previously identified as functionally important in other reptiles. Thus, our results indicate that MC1R is not involved in the pigmentation pattern observed in Liolaemus lizards. Therefore, structural differences in other genes, such as ASIP, or variation in regulatory regions of MC1R may be responsible for this variation. Alternatively, the phenotypic differences observed might be a consequence of non-genetic factors, such as thermoregulatory mechanisms.

Coat genetic markers of the domestic cat Felis catus (Felidae) from southwestern Colombia / Marcadores genéticos del pelaje del gato doméstico Felis catus (Felidae) del suroccidente colombiano

ABSTRACT Objectives. Establish the genetic profiles of cats from 12 neighboring municipalities in southwestern Colombia, in a town course from Pereira-Popayán. Estimate the degree of diversity, genetic structure, and quantify gene flow. Materials and methods. Were inventoried the phenotypic markers present in the pigmentation and structure of the coat of 1482 cats of the municipalities surveyed. Based on these phenotypic frequencies, allele frequencies, heterozygosity, Hardy-Weinberg equilibrium, F statistics and Nei genetic distances were calculated. A comparison was also made between genetic and geographic distance matrices to determine if there was a significant association between the two. Results. With the genetic profiles of the populations we estimated the degree of diversity. We found the populations in equilibrium for the S autosomal locus and for the O sex-linked locus. We found a low level genetic structure, and it was determined that there was no significant correlation between the genetic and geographic distance matrices among populations. Conclusions: These findings can be explained on the basis of the processes of human displacement for this region, due to the fact that the establishment of feline populations in these municipalities originated during the same historical period. Identical genetic profiles are shared as a result of colonization events, and due to possible continued migration among these populations.

RESUMEN Objetivos. Determinar los perfiles genéticos de los gatos de 12 municipios contiguos del suroccidente colombiano en un trayecto Pereira-Popayán; estimar el grado de diversidad, estructura genética y cuantificar el flujo de genes. Materiales y métodos. Se inventariaron los marcadores fenotípicos presentes en la pigmentación y estructura del pelaje de 1482 gatos de los municipios estudiados, con base en estas frecuencias fenotípicas se calcularon frecuencias alélicas, heterocigosidad, equilibrio Hardy-Weinberg, el estadístico FST y distancias genéticas de Nei. También se realizó una comparación entre matrices de distancia genética y geográfica para determinar si existía asociación significativa entre las dos. Resultados. Con los perfiles genéticos de las poblaciones se estimó el grado de diversidad, se halló en equilibrio Hardy-Weinberg a las poblaciones para el locus autosómico S y el locus ligado al sexo O. Se encontró bajo nivel de estructura genética y se determinó que no existe correlación significativa entre las matrices de distancia genética y geográfica entre poblaciones. Conclusiones. Estos hallazgos se pueden explicar con base en los procesos de desplazamiento humano para esta región, debido a que el establecimiento de poblaciones felinas en estos municipios se originó en el mismo período histórico. Se comparten perfiles genéticos idénticos como resultado, posiblemente, de eventos de colonización y migración continua entre estas poblaciones.

Sequence variation in the melanocortin-1 receptor (MC1R) pigmentation gene and its role in the cryptic coloration of two South American sand lizards

In reptiles, dorsal body darkness often varies with substrate color or temperature environment, and is generally presumed to be an adaptation for crypsis or thermoregulation. However, the genetic basis of pigmentation is poorly known in this group. In this study we analyzed the coding region of the melanocortin-1-receptor (MC1R) gene, and therefore its role underlying the dorsal color variation in two sympatric species of sand lizards (Liolaemus) that inhabit the southeastern coast of South America: L. occipitalis and L. arambarensis. The first is light-colored and occupies aeolic pale sand dunes, while the second is brownish and lives in a darker sandy habitat. We sequenced 630 base pairs of MC1R in both species. In total, 12 nucleotide polymorphisms were observed, and four amino acid replacement sites, but none of them could be associated with a color pattern. Comparative analysis indicated that these taxa are monomorphic for amino acid sites that were previously identified as functionally important in other reptiles. Thus, our results indicate that MC1R is not involved in the pigmentation pattern observed in Liolaemus lizards. Therefore, structural differences in other genes, such as ASIP, or variation in regulatory regions of MC1R may be responsible for this variation. Alternatively, the phenotypic differences observed might be a consequence of non-genetic factors, such as thermoregulatory mechanisms.