Plant & Animal Genomes XIV Conference

January 14-18, 2006
Town & Country Convention Center
San Diego, CA

Regulatory Activity Of DNA Sequences Surrounding The Callipyge Mutation On Ovine Chromosome 18

Aurelia Skipwith¹ , Noelle E. Cockett² , Christoher A. Bidwell¹

¹  Department of Animal Sciences, Purdue University, 125 South Russell Street, West Lafayette IN 47907-2042 USA

²  Department of Animal Dairy and Veterinary Sciences, Utah State University, 4800 Old main Hill, Logan UT 84322-4800 USA

The callipyge mutation is a single base pair transition from A (normal) to G (callipyge) in a highly conserved 12 bp motif in the intergenic region between DLK1 and GTL2. The mutation alters the expression of several genes within the 215 kb cluster when the mutation is inherited in cis. It has been hypothesized that the mutation occurred in a long range control element. The objective of this project was to analyze the genetic regulatory role of sequences around the callipyge mutation. Twenty-four Sau3AII fragments from sheep BACs were screened for enhancer activity using a luciferase assay and transient transfection of C2C12 cells. Seventeen luciferase plasmids had significantly higher activity than a minimal promoter plasmid (pGL3P; P < 0.05) indicating they contain enhancer sequences. Two plasmids had significantly lower activity than pGL3P (P < 0.001) indicating they contain repressors. Two luciferase plasmids were constructed containing 1.2 kb of sequence flanking the mutation including the 12 bp motif with either the normal allele (pSNP-N) or callipyge allele (pSNP-C). Both plasmids had significant enhancer activity (P < 0.0001) indicating that the callipyge mutation does not alter that activity. The SNP-N sequence in cloned tandem with the repressor element was not significantly different then the repressor element alone. However the SNP-C sequence in cloned tandem with the repressor element had significant (P < 0.05) enhancer activity. The callipyge mutation may cause a loss of repressor activity at the long range control element in muscle resulting in increased transcription of the genes in cis.