| Abstract: | Males of the American cockroach, Periplaneta americana, received an injection of 32P-orthophosphates and the specific activity of phosphatidylcholine (PC), phosphatidylethanolamine (PE) and phosphatidylinositol (PI) was determined after 120 min of in vivo incorporation. If the insects were forced to fly for 10 min immediately before the end of the experiment, the specific activity (S.A.) of PC and PE was lowered by 34.3 and 31.0%, respectively, that of PI by 17.5%. If the animals were allowed to rest for 10 min after cessation of flight, the S.A. of PC and PE did not differ significantly from the controls, whereas that of PI rose by 91.0% above the control value. These effects cannot be due to changes in precursor labelling (glycerophosphate and phosphoarginine were measured) and reflect changes in the rate of phospholipid biosynthesis. The possibility is discussed that mechanisms regulating the rate of phospholipid biosynthesis are involved. |
