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- Bellone, Rebecca R, et al.
(författare)
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Fine-mapping and mutation analysis of TRPM1 : a candidate gene for leopard complex (LP) spotting and congenital stationary night blindness in horses
- 2010
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Ingår i: Briefings in Functional Genomics & Proteomics. - : Oxford University Press (OUP). - 1473-9550 .- 1477-4062 .- 2041-2649 .- 2041-2657. ; 9:3, s. 193-207
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Tidskriftsartikel (refereegranskat)abstract
- Leopard Complex spotting occurs in several breeds of horses and is caused by an incompletely dominant allele (LP). Homozygosity for LP is also associated with congenital stationary night blindness (CSNB) in Appaloosa horses. Previously, LP was mapped to a 6 cm region on ECA1 containing the candidate gene TRPM1 (Transient Receptor Potential Cation Channel, Subfamily M, Member 1) and decreased expression of this gene, measured by qRT-PCR, was identified as the likely cause of both spotting and ocular phenotypes. This study describes investigations for a mutation causing or associated with the Leopard Complex and CSNB phenotype in horses. Re-sequencing of the gene and associated splice sites within the 105 624 bp genomic region of TRPM1 led to the discovery of 18 SNPs. Most of the SNPs did not have a predictive value for the presence of LP. However, one SNP (ECA1:108,249,293 C>T) found within intron 11 had a strong (P < 0.0005), but not complete, association with LP and CSNB and thus is a good marker but unlikely to be causative. To further localize the association, 70 SNPs spanning over two Mb including the TRPM1 gene were genotyped in 192 horses from three different breeds segregating for LP. A single 173 kb haplotype associated with LP and CSNB (ECA1: 108,197,355- 108,370,150) was identified. Illumina sequencing of 300 kb surrounding this haplotype revealed 57 SNP variants. Based on their localization within expressed sequences or regions of high sequence conservation across mammals, six of these SNPs were considered to be the most likely candidate mutations. While the precise function of TRPM1 remains to be elucidated, this work solidifies its functional role in both pigmentation and night vision. Further, this work has identified several potential regulatory elements of the TRPM1 gene that should be investigated further in this and other species.
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| 2. |
- Staiger, Elizabeth Ann, et al.
(författare)
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Morphological Variation in Gaited Horse Breeds
- 2016
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Ingår i: Journal of Equine Veterinary Science. - : Elsevier BV. - 0737-0806 .- 1542-7412. ; 43, s. 55-65
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Tidskriftsartikel (refereegranskat)abstract
- Gaited horses, renowned for their smooth gaits, are anecdotally noted to have proportionally longer hind limbs than nongaited breeds of the same height. However, gaited horses perform a wide spectrum of different gaits that we hypothesize may require diverse skeletal adaptations. To investigate the contribution of morphology to gait ability, we collected body measurements from gaited and nongaited individual animals and principal component analysis was conducted on 32 body measures for a set of 1,682 horses. Principal component (PC) 1 captured 65.3% of the trait variance, whereas PC2 comprised 6.6% and PC3 3.2% of variance in the data set. All body measures correlated positively with PC1 which quantifies a horse's overall body size. In contrast, PC2 quantifies body thickness. Principal component 3 represents a pattern primarily involving skull thickness and lower limb length. Because of the presence of sexual dimorphism and unequal sampling across sexes, we generated a pruned data set of 432 individuals with equal numbers of gaited and nongaited horses within each sex class. Analysis of variance and pairwise correlations were conducted to identify differences in the PC scores and measurements (normalized by wither height) due to sex, gait phenotype, breed, and age. After accounting for these fixed effects, gaited horses were significantly different from nongaited horses in PC2 and PC3 (P <. 0001). Comparisons of individual measurements demonstrate that gaited horses have smaller eye and jaw widths, proportionally longer front limb segments and thinner lower limb circumferences (P <. 05). This is the first study to identify different proportions in the front limb segments associated with gait.
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