Experiment
The C57BL/6J-ChrA/J/NaJ (B6.A) panel of chromosome substutution strains (CSSs) is a unique model for studying resistence to diet induced obesity. C57BL/6J male mice are significantly more susceptible than A/J males to diet induced obesity. In the present study 20 CSS intercrosses, one derived from each of the 19 autosomes and chromosome X, were used to determine the number and location of quantitative trait loci (QTL) on individual chromosomes.
CSS females were crossed with C57BL/B6 (B6) males), F1 offspring were then intercrossed to generate F2 male progeny, 75-93 per CSS cross. QTL analysis on the intercosses between each CSS strain (except CSS-Y and CSS-Mito) and the B6 host strain revealed significant QTL on Chromosomes 1, 6, 10, 11, and 13. The analysis was performed testing for QTL that affected:
IW, weight in grams at app 35 days of age;
MW, weight in grams at app 90 days of age;
FW, weight in grams at app 135 days of age;
BMI, FW in grams / final nasonanal length in cms;
EWG, mean weight gain per day in grams/day for app first 55 days;
FWG, mean weight gain per day in grams per day for second app 45 days;
WG, mean weight gain per day in grams/per day.
On Chromosome 11 (C57BL/6J-Chr 11A/J/NaJ x C57BL/6J) the following significant QTL was identified:
Obrq6 (obesity resistance QTL 6) mapped to Chr 16 at 49 cM in a 1.5 LOD support interval between 38-55 cM with a LOD=4.60, p=0.041 for trait WG.
The following suggestive QTL were also identified on Chr 11:
at 49 cM, spanning 31-57 cM, LOD=4.02, p=0.11, affecting trait FW;
at 47 cM, spanning 32-47 cM, LOD=3.91, p=0.14, affecting trait BMI; and
at 49 cM, spanning 40-58 cM, LOD=4.16, p=0.09, infuencing trait FWG.
[Table 2 and Sup Table 5].
Analysis Tools