Experiment
A previously mapped QTL showing suggestive linkage to body composition traits mapped to mouse Chromosome 7 (Reed et al, 2006, J:116161). The current study confirms the existence of the QTL(s) using chromosome substitution strain analysis. C57BL/6J-Chr7129S1/SvImJNa is a chromosome substitution strain carrying chromosome 7 derived from 129S1/SvImJNa on a C57BL/6J genetic background. Animals were phenotyped at 14-weeks of age for body weight, adipose tissue weight, organ weight, and bone composition traits. Several sex-dependent QTL for body composition were identified and require further mapping to define the QTL regions.
Chromosome substitution strain B6-Chr7129 had larger litter sizes compared to background strain C57BL/6J and this difference was statistically significant. This locus is named Litsq (litter size QTL).
Male B6-Chr7129 animals display decreased body weight and fat pad depots (gonadal, retroperitoneal, suscapular, inguinal) compared to C57BL/6J males. Only the mesenteric fat depot was larger in B6-Chr7129 males. This locus is named Bdwtq (body weight QTL). There was no difference in body weight or fat depot weight between female animals.
Female B6-Chr7129 animals displayed decreased heart weight, bone area, and bone mineral content compared to C57BL/6J females. The heart weight locus is named Hrwq (heart weight QTL), and the bone trait locus is named Boneq (bone trait QTL).
Brain weight was decreased in both male and female B6-Chr7129 animals compared to C57BL/6J (bothsexes). This locus is named Brnwq (brainweight QTL).