Experiment
Linkage analysis was performed on 515 (EMH x EML)F2 animals to identify QTL associated with body mass. Parentals EMH and EML are high- and low-food intake selection lines, respectively. Animals were phenotyped for body mass at 14, 16, and 18 weeks of age. Genome scan was performed using 87 polymorphic markers at an average spacing of 23.6 cM. Three loci reaching high statistical significance (p<0.01) are reported below.
Bw23 (body mass QTL 1) is associated with body mass at 16 weeks of age and mapped to 73 cM on mouse Chromosome 5. This locus explains 4.89% of the phenotypic variance. Potential candidate genes for Bw23 are Vgf (79 cM) and Ipf1 (82 cM). Bglq14 (78 cM) and Bw13 (81 cM) are two previously identified body/growth trait QTL mapping near Bw23.
Bw24 (body mass QTL 2) is associated with body mass at 18 weeks of age and mapped to 49 cM on mouse Chromosome 7. This locus explains 4.7% of the phenotypic variance and also shows suggestive linkage to body mass at 14 and 16 weeks of age. The 1-LOD support interval of Bw24 spans 35 cM - 68 cM. Potential candidate genes for Bw24 are Tub (51.45 cM), Ucp2 (50 cM), and Ucp3 (50 cM). W10q18 (18.2 cM), Bw14 (28 cM), and Bglq6 (50 cM) are previously identified body/growth trait QTL mapping near the Bw24 interval.
Impbw1 (body mass QTL 3) mapped to 7 cM on mouse Chromosome 8 and exhibits a paternal imprinting effect. This locus had the largest effect and is associated with body mass at 14, 16, and 18 weeks of age accounting for 12.34%, 12.29%, and 10.65% of the phenotypic variance, respectively. The 1-LOD support interval of Impbw1 spans approximately 1 cM - 23 cM. Potential candidate genes for Impbw1 are Adrb3 (10 cM) and Irs2 (5 cM). W10q14 (26.4 cM), Wg3 (45 cM), and Bwq3 (56 cM) are previously identifiedbody/growth trait QTL mapping near the Impbw1 interval.
Suggestive body mass loci mapped to 11 cM on mouse Chromosome 2, 61 cM on mouse Chromosome 3, 55 cM on mouse Chromosome 4, 40 cM on mouse Chromosome 9, 8 cM on mouse Chromosome 14, 53 cM on mouse Chromosome 16,35 cM on mouse Chromosome 18, and 10 cM on mouse Chromosome 19.