QUANTITATIVE TRAIT LOCI FOR MURINE GROWTH

Body size is an archetypal quantitative trait with variation due to th e segregation of many gene loci, each of relatively minor effect, and the environment. We examine the effects of quantitative trait loci (QT Ls) on age-specific body weights and growth in the F-2 intercross of t he LG/J and SM/J strains of inbred mice. Weekly weights (1-10 wk) and 75 microsatellite genotypes were obtained for 535 mice. Interval mappi ng was used to locate and measure the genotypic effects of QTLs on bod y weight and growth. QTL effects were detected on 16 of the 19 autosom es with several chromosomes carrying more than one QTL. The number of QTLs for age-specific weights varied from seven at 1 week to 17 at 10 wk. The QTLs were each of relatively minor, subequal effect. QTLs affe cting early and late growth were generally distinct, mapping to differ ent chromosomal locations indicating separate genetic and physiologica l systems for early and later murine growth.