DISTRIBUTION OF RADIOACTIVITY IN OZONIDE DEGRADATION PRODUCTS DERIVED FROM GLYCEROPHOS - PHATIDE POLYENOIC ACIDS OF CHICK EMBRYONIC BRAIN AFTER INCUBATION WITH ACETATE - 1 - 14 C Product Radioactivity

The incorporation of acetate-1 J4C into the polyunsaturated fatty acids of glycerophosphatides of chick embryonic brain has been studied. After the injection of acetate-l-14C into the yolk sac, differences were found in the degree of labeling of the major fatty acids of the w3 and w 6 series. Arachidonic acid (20:406) showed a high degree of radioactivity while docosahexaenoic acid (22 : 6w3) was poorly labeled, at a period of brain development when both fatty acids were being actively deposited. Evidence is presented to indicate that the low activity in docosahexaenoic acid is not explicable on the basis of either a low or high rate of turnover of this polyenoic acid. Similar results were obtained whether the rapid early or slower late stage of brain development was examined. It is suggested that the elongation of w 3 and w6 series acids may be under the control of different regulatory mechanisms.