INCORPORATION OF GLUCOSE-U-14C INTO LIPIDS OF BLOWFLY DURING FLIGHT

Incorporation of the label from glucose-U-14C into lipids of the blowfly, Phaenicia sericata, was studied during flight and at rest. After 3 hr of continuous flight following injection of the glucose, only 0·5 per cent of the radioactivity was found in lipids, whereas 1·0 per cent was recovered from flies at rest for 3 hr. Resting females incorporated more glucose into lipid than resting males, whereas during flight the rate of incorporation was the same for both sexes. The label in triglyceride increased with time in both resting and flying flies. About twice as much label was found in the glycerol portion of glycerides and phospholipids as compared to the fatty acid portion. Some label was found in hydrocarbons. Flight activity, although accompanied by an increase in metabolism, appears to decrease the rate of conversion of glucose into lipid. Since carbohydrate is the main source of flight energy in Diptera, a mechanism to conserve the level of carbohydrate during flight would seem to be desirable. © 1969.