ABSTRACT
Common Moroccan breeds D'man, Sardi, and Timahdite have been found to differ regarding litter size. D'man is known for its high prolificacy (2-7 lambs), whereas Timahdite and Sardi are normally prolific (1-2 lambs). Here, we aimed to identify genetic variants in the ß promoter and to study the promoter activity amongst these breeds using sequencing for the former and the in vitro luciferase assay for the latter. Sequence analysis revealed 16 genetic variants among these common breeds. Luciferase assay analysis demonstrated a higher promoter activity in D'man compared to the Sardi/Timahdite breeds. A small region of 541 bp was further characterized as possessing a high promoter activity. This region contains 2 palindromic sequences and 7 variants. Based on in silico analysis, only 2 variants at position -559 and -568 were found to be informative. These 2 variants were localized within a region rich in transcription factor binding sites including GATA-1/GATA-2, E4/th1, CP2, and c-Ets. Using site-directed mutagenesis, only the variant at position -559 A/G was found to substantially influence the promoter activity. Taken together, differences in the level of ß transcription among highly and minimally prolific Moroccan breeds were demonstrated and a novel single variant was identified that could explain this difference.
Subject(s)
Genetic Variation , Litter Size/genetics , Sheep, Domestic/genetics , Animals , Base Sequence , Female , Luciferases , Molecular Sequence Data , Morocco , Mutagenesis, Site-Directed , Promoter Regions, Genetic/genetics , Sequence Analysis, DNA/veterinary , Sheep , Species SpecificityABSTRACT
Dystrophic cardiac calcinosis (DCC) occurs among certain inbred strains of mice and involves necrosis and subsequent calcification as response of myocardial tissue to injury. Using a complete linkage map approach, we investigated the genetics of DCC in an F(2) intercross of resistant C57BL/6J and susceptible C3H/HeJ inbred strains and identified previously a major predisposing quantitative trait locus (QTL), Dyscalc1, on proximal chromosome 7. Analysis of inheritance suggested, however, that DCC is influenced by additional modifier QTL, which have as yet not been mapped. Here, we report the identification by composite interval mapping of the DCC loci Dyscalc2, Dyscalc3, and Dyscalc4 on chromosomes 4, 12 and 14, respectively. Together, the four Dyscalc loci explained 47% of the phenotypic variance of DCC, which was induced by a high-fat diet. Additive epistasis between Dyscalc1 and Dyscalc2 enhanced DCC. Examining recombinant inbred strains, we propose a 10-cM interval containing Dyscalc1 and discuss potential candidate genes.
