TEMPERATURE-ACCLIMATION OF TRYPANOSOMA-CRUZI EPIMASTIGOTE AND METACYCLIC TRYPOMASTIGOTE LIPIDS

This study examines the changes in cellular lipids that take place whe n Trypanosoma cruzi epimastigotes and metacyclic trypomastigotes are t ransferred from 28 to 37 degrees C. We found a rise in the sterol to p hospholipid ratio, as well as in the triacylglycerol and steryl ester cellular content in T. cruzi epimastigotes. Ln addition, saturated to unsaturated fatty acid ratios in phospholipids increase. This latter e ffect appears to be due to two concurrent processes. Firstly, fatty ac yl Delta 9 and, especially, Delta 12 desaturations are significantly d iminished at 37 degrees C. Secondly, triacylglycerols and steryl ester s undergo changes in their fatty acyl composition opposite to those si multaneously observed in phospholipids, i.e. the ratio of saturated to unsaturated fatty acids markedly decreases. Similar alterations in ea ch of the lipid classes and in the fatty acid composition of polar and neutral lipids were found in cultured metacyclic trypomastigotes on e xposure to the same shift-up. These observations suggest that. a globa l remodelling of cellular lipids that involves extensive fatty acid ex change between neutral and polar lipid pools represents a novel and im portant mechanism of adaptation of the parasites to the temperature ch anges they encounter in their life cycle. (C) 1997 Elsevier Science B. V.