MECHANISM OF THERMAL ADAPTATION OF MEMBRANE LIPIDS IN TETRAHYMENA-PYRIFORMIS NT-1 - POSSIBLE EVIDENCE FOR TEMPERATURE-MEDIATED INDUCTION OF PALMITOYL-COA DESATURASE

Abstract

The regulatory mechanism of a key enzyme, palmitoyl-CoA desaturase, involved in the adaptation to temperature shift was investigated by labeling T. pyriformis cells with [14C]palmitic acid. The rate of conversion of [14C]palmitate to [14C]palmitoleate was dependent on incubation temperature and was maximal at 2 h after the shift from 39.5.degree. to 15.degree. C. Addition of cycloheximide before the temperature shift produced no increase in desaturation of [14C]palmitate after the shift. These data provide evidence for temperature-triggered increase of palmitoyl-CoA desaturase level and are discussed in relation to membrane fluidity.