Whole-Genome Resequencing Reveals Genetic Structure and Introgression in Chinese Pudong White Pigs

Background: Pudong white (PDW) pigs originating from Shanghai, are the only Chinese indigenous pigs with white coat color except Rongchang (RC) pigs. However, there is limited information about its overall genetic structure, relationship with other breeds especially the East Chinese (ECN) and European pig due to the white coat of PDW. Whole-genome sequencing provides the effective approach to get the unique information of genome. The high-depth whole-genome sequencing data of 26 global pig breeds, European Wild boars (EWB), Chinese Wild boars (CWB) and out group (OUT) were implemented to detect the genetic structure, signature of selection and potential exotic introgression in PDW pigs.Results: The PDW pigs belonging to ECN pigs based on genetic relationship, and harbor lower genetic diversity and higher inbreeding coefficient compared to other Chinese indigenous pigs. Both the f3 and D-statistics analysis demonstrated that PDW pigs shared apparent alleles with Large White (LW) pigs. Then, two statistics, haplotype heat-map, copy number variation (CNV) and rIBD analysis further revealed that PDW pigs carry the same KIT genotype and share haplotypes at PARG-MARCHF8 locus with LW pigs, suggesting that the lineage of European (EUR) pigs in PDW originated from LW pigs. After detecting the KIT mutations in different pig breeds, PDW was confirmed to be same with LW at DUP1, DUP2 and the splicing mutation on intron 17 of KIT which determine the white coat color phenotype in European white pigs.Conclusions: This study shows that ECN pigs crossed with LW pigs after introduced to China about 110-164 years ago, where the offspring carrying KIT genotype that caused white coat color phenotype, and then were selected due to the rare white coat color in Chinese indigenous pigs, gradually forming PDW pig breed. To our knowledge, this study gives the first thorough description of the genetic structure of PDW pig via whole-genome resequencing data. This study not only advances our understanding of genetic structure, molecular phylogeny, and molecular origin of PDW pigs, but also provides a basis for facilitating the development of a national project for the conservation and utilization of this unique Chinese local population.

The mutations within MC1R, TYRP1, ASIP genes and their effects on phenotypes of coat color in wild pigs (Sus scrofa ussuricus )

Animal coloration is a powerful model for studying the genetic mechanisms that determine animal phenotypes. But, there has not been comprehensive characterization of the molecular basis of the complex patterns of coat color phenotype variation in wild boars. This study results indicated that the wild-type allele E+ of the MC1R gene was a dominant allele in wild boars and was not responsible for black, brown or other coat color phenotypes. A novel mutation c.695 T > C was identified in the 3¢-UTR of the ASIP gene. The association analysis showed that the C mutation allele was highly significantly associated with wild-type coat colors between wild boars and Western pig breeds (P=1.35E-33). A non-synonymous g.2254 G > A substitution was found in exon 2 of the TYRP1 gene (p.143His>Arg). The association analysis demonstrated that the G mutation allele was also significantly associated with wild-type coat colors between wild boars and Western pig breeds (P = 5.09E-10). In short, a few mutation sites in MC1R, ASIP, and TYRP1 genes were identified and surveyed several polymorphisms molecular variations in Chinese wild boars. In our identified mutations have caused the morphological diversity in wild boars, but did not influence coat color phenotype variation in some domesticated pig breeds. The conclusion was obtained that some mutations in color-associated genes were associated with wild-type coat colors in wild boar population, and that similar coat colorations observed in domesticated pig and wild boars can be the product of underlying differences in the genetic basis of color variants.

Mutations inMC1RGene Determine Black Coat Color Phenotype in Chinese Sheep

The melanocortin receptor 1 (MC1R) plays a central role in regulation of animal coat color formation. In this study, we sequenced the complete coding region and parts of the 5′- and 3′-untranslated regions of theMC1Rgene in Chinese sheep with completely white (Large-tailed Han sheep), black (Minxian Black-fur sheep), and brown coat colors (Kazakh Fat-Rumped sheep). The results showed five single nucleotide polymorphisms (SNPs): two non-synonymous mutations previously associated with coat color (c.218 T>A, p.73 Met>Lys. c.361 G>A, p.121 Asp>Asn) and three synonymous mutations (c.429 C>T, p.143 Tyr>Tyr; c.600 T>G, p.200 Leu>Leu. c.735 C>T, p.245 Ile>Ile). Meanwhile, all mutations were detected in Minxian Black-fur sheep. However, the two nonsynonymous mutation sites were not in all studied breeds (Large-tailed Han, Small-tailed Han, Gansu Alpine Merino, and China Merino breeds), all of which are in white coat. A single haplotype AATGT (haplotype3) was uniquely associated with black coat color in Minxian Black-fur breed (P=9.72E-72, chi-square test). The first and second A alleles in this haplotype 3 represent location at 218 and 361 positions, respectively. Our results suggest that the mutations ofMC1Rgene are associated with black coat color phenotype in Chinese sheep.

Soy Protein Isolate Reduces Hepatosteatosis in Yellow Avy/a Mice Without Altering Coat Color Phenotype

Agouti ( A vy/ a) mice fed an AIN-93G diet containing the soy isoflavone genistein (GEN) prior to and during pregnancy were reported to shift coat color and body composition phenotypes from obese-yellow towards lean pseudoagouti, suggesting epigenetic programming. Human consumption of purified GEN is rare and soy protein is the primary source of GEN. Virgin a/a female and Avy/a male mice were fed AIN-93G diets made with casein (CAS) or soy protein isolate (SPI) (the same approximate GEN levels as in the above mentioned study) for 2 wks prior to mating. A vy /a offspring were weaned to the same diets and studied at age 75 d. Coat color distribution did not differ among diets, but SPI-fed, obese A vy/ a offspring had lower hepatosteatosis ( P < 0.05) and increased ( P < 0.05) expression of CYP4a 14, a PPARα-regulated gene compared to CAS controls. Similarly, weanling male Sprague-Dawley (SD) rats fed SPI had elevated hepatic Acyl Co-A Oxidase (ACO) mRNA levels and increased in vitro binding of PPARα to the PPRE promoter response element. In another hepatosteatosis model, adult SD rats fed a high fat/cholesterol diet, SPI reduced ( P < 0.05) steatosis. Thus, 1) consumption of diets made with SPI partially protected against hepatosteatosis in yellow mice and in SD rats, and this may involve induction of PPARα-regulated genes; and 2) the lifetime ( in utero, neonatal and adult) exposure to dietary soy protein did not result in a shift in coat color phenotype of A vy/ a mice. These findings, when compared with those of previously published studies of A vy/ a mice, lead us to conclude that: 1) the effects of purified GEN differ from those of SPI when GEN equivalents are closely matched; 2) SPI does not epigenetically regulate the agouti locus to shift the coat color phenotype in the same fashion as GEN alone; and 3) SPI may be beneficial in management of non-alcoholic fatty liver disease