Phospholipid molecular species alterations in Tetrahymena ciliary membranes following low-temperature acclimation

The molecular species compositions of phosphatidylcholine, phosphatidylethanolamine, and 2-(aminoethyl)-phosphonolipid, the three principal phosphoglycerides of Tetrahymena pyriformis ciliary membranes, have been determined by coupled gas chromatography-mass spectrometry of the tert-butyldimethylsilyl derivatives of their phospholipase C derived diglycerides. There were striking changes in the molecular species composition of phosphatidylcholine and phosphatidylethanolamine after the cells were chilled from 39 to 15 degrees C. The low temperature induced changes occurring in each phospholipid class were markedly different from those taking place in the other two. The molecular species patterns of the ciliary phosphoglycerides resembled in a qualitative way the patterns found in their microsomal counterparts. However, the relative proportions of many molecular species within each ciliary phospholipid class were very different from those of the corresponding microsomal component, and changes induced in a particular microsomal phospholipid class by chilling were often absent or even reversed in the equivalent ciliary phospholipid. Compositional changes in ciliary phospholipids during low-temperature acclimation were greater in nearly all respects than were concurrent changes in microsomal phospholipids. The molecular species data confirm that the cell possesses a variety of highly selective mechanisms allowing those organelles which accept phospholipids of microsomal origin to retain a surprising degree of independence in responding to environmental stress.