Incorporation of 14C acetate into lipids of the ICR mouse lens

Lenses from ICR mice 6, 12 and 35 days of age were incubated with 14C acetate in Medium 199 for 10 hours, and lenses from 35-day-old mice were also incubated for 18 hours. Acetate was incorporated into the phospholipid and free fatty acid fractions. Minimal radioactivity was incorporated into cholesterol. Phosphatidyl choline was the major labeled phospholipid. The longer incubation time resulted in a decrease in the total amount of label retained, indicating a fatiguing of the incubation system. The free fatty acids were extracted and subjected to analysis by gas chromatography. Although myristic acid (14:0) accounted for only 4% to 6% of the free fatty acids, it had the highest specific activity and the greatest percentage of incorporated radioactivity of the fatty acids for the 10-hour incubation period. The specific activity of all the fatty acids decreased dramatically after 18 hours incubation. Palmitic acid (16:0) had the greatest incorporation of label. It was suggested that exogenous acetate in the mouse lens preferentially entered a pool for energy production or storage rather than a pool for the synthesis of structural lipids as evidenced by minimal incorporation into cholesterol.