Experiment
QTLs associated with weight loss on dietary restriction were mapped using 5 cohorts of 81 different inbred and recombinant inbred strains. A panel of 266 polymorphic markers at an average resolution of 5 cM was used for the genome scan. Female animals eating 60% ad libitum diet were tested for weight loss response.
In LXS recombinant inbred (RI) animals, weight loss response loci Wtlr1 and Wtlr2 mapped to 19 cM on mouse Chromosome 6 near D6Mit223 (LOD=1.3) and 22 cM on mouse Chromosome 16 near D16Mit103(LOD=1.3), respectively. These loci are associated with weight loss at weeks 7-16 of dietary restriction. Linkage to weight loss response at weeks 17-30 of dietary restriction mapped to 14 cM on mouse Chromosome 4 near D4Mit286 (LOD=2.1) and 18 cM on mouse Chromosome 7 near D7Mit270 (LOD=1.8). These loci are named Wtlr3 (weight loss response 3) and Wtlr4 (weight loss response 4), respectively. Wtlr1-Wtlr4 collectively account for 54% of the genetic variance. Epsistatic interaction was observed between loci on chromosomes 1 and 4, and chromosomes 14 and X at weeks 17-30 of dietary restriction.
In LSXSS RI animals, suggestive linkage to weight loss response mapped to mouse Chromosomes 1 (43 cM), 4 (59 cM), 8 (28 cM), 9 (71 cM), 11 (37 cM), and 13 (29 cM).Epistatic interaction reaching suggestive statistical significance were detected between chromosomes 2 and 4 for week 7-16 of dietary restriction, and between chromosomes 3 and 4 for weeks 17-30 of dietary restriction.