I-08 Genetic dissection of closely linked quantitative trait loci affecting body weight and obesity on mouse chromosome 2

Better understanding of the genetic architecture of a quantitative trait in most, organisms remains elusive because variation iii the trait is controlled by multiple genetic loci, referred to as QTLs(quantitative trait loci), and environments, and also by QTL-QTL and QTL-environment, interactions. Body weight and obesity are the typical examples of complex quantitative traits. Previously we have developed the congenic mouse strain, named B6.Cg-Pbwg1, with a 44.1-Mb donor region from the Philippine wild mouse(Mus musculus castaneus) onto the genetic background of the C57BL/6J inbred strain. Pbwg1 is a QTL affecting body weight and growth previously identified on mouse chromosome 2. Further QTL analysis in an intercross population between B6.Cg-Pbwg1 and C57BL/6J has revealed that several body weight and obesity QTLs are closely linked. Subcongenic analysis is well known to be a powerful method for dissecting linked QTLs physically. In this study, we developed a series of 17 subcongenic strains from B6.Cg-Pbwg1. Phenotypic analyses of several overlapping and nonoverlapping subcongenic regions revealed that one region prevents obesity whereas another region increases body weight and lean body weight.