FETAL BOVINE SERUM INDUCES CHANGES IN FATTY-ACID COMPOSITION OF TRYPANOSOMA-CRUZI PHOSPHOINOSITIDES

Fetal bovine serum (FBS) is a necessary constituent of the culture media employed to foster the growth of Trypanosoma cruzi epimastigote forms. In different laboratories, the serum is used at final concentrations of 5 or 10%. We have normally supplemented the complex medium with 10% FBS. Under this condition we have described the fatty acid composition of the total lipids and of the phosphoinositide fractions. Additionally, we have reported the increase of polyphosphoinositides and phosphatidic acid after cholinergic stimulation. Since further attempts to reproduce these results with 5% FBS in the culture medium were not successful, the effect of the FBS concentration on the fatty acid composition of phospholipids from the T. cruzi epimastigote forms was thoroughly examined. This work showed that when the FBS concentration supplementing the culture medium was reduced from 10 to 5%, the fatty acid composition of the phosphoinositides was altered while the other major phospholipids were not significantly affected. The most relevant result was the decrease in the content of linoleic acid (18:2) and the increase of palmitoleic acid (16:1) in phosphatidylinositol 4,5-bisphosphate. Phosphatidylinositol (PI) and phosphatidylinositol phosphate also exhibited similar changes in the same fatty acids. The C-2 fatty acid composition of the phosphoinositides, under the same conditions, is also reported here for the first time.