Haplotype variability in the bovine MITF gene and association with piebaldism in Holstein and Simmental cattle breeds.
ABSTRACT Candidate gene analysis, quantitative trait locus mapping in outbreed and experimental cross-populations and a genomewide association study in Holstein have reported that a few chromosome regions contribute to great variability in the degree of white/black spotting in cattle. In particular, an important region affecting this trait was localized on bovine chromosome 22 in the region containing the microphthalmia-associated transcription factor (MITF) gene. We sequenced a total of 7258 bp of the MITF gene in 40 cattle of different breeds, including 20 animals from spotted breeds (10 Italian Holstein and 10 Italian Simmental) and 20 animals from solid coloured breeds (10 Italian Brown and 10 Reggiana), and identified 17 single nucleotide polymorphisms (SNPs). The allele frequencies of one polymorphism (g.32386957A>T) were clearly different between spotted (A = 0.875; T = 0.125) and non-spotted breeds (A = 0.125; T = 0.875) (P = 8.2E-12). This result was confirmed by genotyping additional animals of these four breeds (P < 1.0E-20). A total of 21 different haplotypes were inferred from the sequenced animals. Considering similarities among haplotypes, spotted and non-spotted groups of cattle showed significant differences in their haplotype distribution (P = 0.001), which was further supported by the analysis of molecular variance (amova) of two genotyped SNPs in an enlarged sample of cattle. Variability in the MITF gene clearly explained the differences between spotted and non-spotted phenotypes but, at the same time, it is evident that this gene is not the only genetic factor determining piebaldism in Italian Holstein and Italian Simmental cattle breeds.
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ABSTRACT: To elucidate the genes involved in the formation of white and black plumage in ducks, RNA from white and black feather bulbs of an F(2) population were analyzed using RNA-Seq. A total of 2,642 expressed sequence tags showed significant differential expression between white and black feather bulbs. Among these tags, 186 matched 133 annotated genes that grouped into 94 pathways. A number of genes controlling melanogenesis showed differential expression between the two types of feather bulbs. This differential expression was confirmed by qPCR analysis and demonstrated that Tyr (Tyrosinase) and Tyrp1 (Tyrosinase-related protein-1) were expressed not in W-W (white feather bulb from white dorsal plumage) and W-WB (white feather bulb from white-black dorsal plumage) but in B-B (black feather bulb from black dorsal plumage) and B-WB (black feather bulb from white-black dorsal plumage) feather bulbs. Tyrp2 (Tyrosinase-related protein-2) gene did not show expression in the four types of feather bulbs but expressed in retina. C-kit (The tyrosine kinase receptor) expressed in all of the samples but the relative mRNA expression in B-B or B-WB was approximately 10 fold higher than that in W-W or W-WB. Additionally, only one of the two Mitf isoforms was associated with plumage color determination. Downregulation of c-Kit and Mitf in feather bulbs may be the cause of white plumage in the duck.PLoS ONE 01/2012; 7(5):e36592. · 3.73 Impact Factor
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ABSTRACT: Recently, genome wide DNA markers have been used in breeding value estimation of livestock species. The computational technique is known as genomic selection. Typically, a large number of marker effects are estimated from a small number of animals, which presents an under-determined problem. In this paper, we propose sparse marker selection methods using haplotypes for both breeding value estimation and QTL mapping. By applying a two-stage regression strategy, markers are selected in the first stage, then in the second stage the selected markers are fitted in a range of models including linear, kernel and semi-parametric models. The estimation accuracy of breeding values is measured by the correlation coefficient, as well as the regression coefficient, between the true breeding values and the estimated breeding values by the models. We show that the estimation accuracy by using sparse markers, as low as 5000 or 500 dimensions, is comparable to that obtained from genome wide markers of about 230,000 dimensions of DNA haplotypes. The selected sparse markers can also be used for QTL mapping. In this paper we use protein yield to demonstrate the methods, and show that loci of large effects confirm published QTL.Mathematical biosciences 02/2013; · 1.30 Impact Factor
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ABSTRACT: White Galloway cattle exhibit three different white coat colour phenotypes, that is, well marked, strongly marked and mismarked. However, mating of individuals with the preferred well or strongly marked phenotype also results in offspring with the undesired mismarked and/or even fully black coat colour. To elucidate the genetic background of the coat colour variations in White Galloway cattle, we analysed four coat colour relevant genes: mast/stem cell growth factor receptor (KIT), KIT ligand (KITLG), melanocortin 1 receptor (MC1R) and tyrosinase (TYR). Here, we show that the coat colour variations in White Galloway cattle and White Park cattle are caused by a KIT gene (chromosome 6) duplication and aberrant insertion on chromosome 29 (Cs(29) ) as recently described for colour-sided Belgian Blue. Homozygous (Cs(29) /Cs(29) ) White Galloway cattle and White Park cattle exhibit the mismarked phenotype, whereas heterozygous (Cs(29) /wt(29) ) individuals are either well or strongly marked. In contrast, fully black individuals are characterised by the wild-type chromosome 29. As known for other cattle breeds, mutations in the MC1R gene determine the red colouring. Our data suggest that the white coat colour variations in White Galloway cattle and White Park cattle are caused by a dose-dependent effect based on the ploidy of aberrant insertions and inheritance of the KIT gene on chromosome 29.Animal Genetics 02/2013; · 2.58 Impact Factor