Analysis of lines of mice selected for fat content: 3. Flux through thede novolipid synthesis pathway

Abstract

SummaryThe flux through thede novofatty acid synthesis pathway was estimated in lines of mice which differed substantially in fat content following 26 generations of selection at 10 weeks of age. Previous estimates of lipogenic enzyme activities had indicated an increase in the capacity for lipogenesis in the Fat compared to the Lean line. Therefore thein vivoflux in lipogenesis was measured in both liver and gonadal fat pad (GFP) tissues of males at 5 and 10 weeks of age, using the rat of incorporation of3H from3H2O and14C from acetate and citra te into total lipids. AT both ages and in both tissues the Fat line had a higher flux, about 20% increase in the liver and up to three-fold increase (range 1·2- to 3·4-fold) in the GFP. We conclude that direct selection for fatness in mice has resulted in metabolic changes in the ratio ofde novofatty acid synthesis, and that the changes are largely detectable before 10 weeks, the age of selection.