Hepatic lipogenesis gene expression in two experimental egg-laying lines divergently selected on residual food consumption

Two Rhode Island Red egg-laying lines have been divergently selected on res idual food intake (low intake R- line, high intake R+ line) for 19 generati ons. In addition to direct response, correlated responses have altered seve ral other traits such as: carcass adiposity anti lipid contents of several tissues, the R+ animals being leaner than the R- ones. In a search for the biological origin of the differences observed in Fat deposit, the hepatic m RNA amounts of genes involved in lipid metabolism were investigated. No dif ference was found between lines for mRNA levels of ATP citrate-lyase, acety l-CoA carboxylase, fatty acid synthase, malic enzyme and CCAAT/enhancer bin ding protein alpha, a transcription factor acting on several lipogenesis ge nes, The genes coding for stearoyl-CoA desaturase and apolipoprotein A1 dis played significantly lower mRNA levels in the R+ cockerels compared to the R-. All together these mRNA levels explained 40% of the overall variability of abdominal adipose tissue weight, suggesting an important role of Loth g enes in the fatness variability.