Altered translation efficiency in mutant mammary glands. (a) Semi-quantitative reverse transcription-polymerase chain reaction (RT-PCR) on α-lactalbumin (Lalba), β-casein (Csn2), Δ6 fatty acid desaturase 2 (Fads2), stearoyl-CoA desaturase 2 (Scd2), elongation of very long chain fatty acids (Elovl1), aldolase C (Aldo3) and β-actin (Actb) in wild type (WT) (W) and mutant (M) glands taken at different time points during lactation. (b) Polysome profiles of day 4.5 lactating mammary glands (upper panel) and corresponding livers (lower panel) of the same animals. Profiles were overlaid according to their 80S peak. Hollow arrowheads mark the peaks of the polysomal fractions. (c) Semi-quantitative RT-PCR on mRNA isolated from the indicated gradient fractions from WT and mutant polysomes. mRNA distribution analyzed for genes described in (a) (upper panel) and 'control genes' β-actin, CK18, and GAPDH (lower panel). Hollow arrowheads indicate the peak of each mRNA distribution along the gradient. (d) Western analysis of β-casein (loading: 0.25 μg per lane) and α-tubulin (loading: 50 μg per lane of the identical lysates) on WT and mutant mammary gland lysates obtained at three time points in lactation.