Gas chromatography/mass spectrometry (GC/MS) of lipids from Tetrahymena thermophila and Andalucia incarcerata. (A) Total ion chromatograms of lipid extracts as trimethylsilyl (TMS) derivatives obtained by GC/MS analyses, and mass spectrum for (B) tetrahymanol and (C) gammacer-2-ene. Tetrahymanol and gammacer-2-ene were identified by coincidence in the mass spectra of the previous study . Both tetrahymanol and gammacer-2-ene were obtained in the lipid extracts from Tetrahymena thermophila and Andalucia incarcerata, but not in those from bacterial prey of A. incarcerata. Although an unknown peak was observed in the chromatogram of bacterial prey with the retention time (44.7 min), the mass spectrum of this peak was completely different from that of tetrahymanol. No peaks corresponding to those of sterols were found in the chromatograms of T. thermophila, A. incarcerata, and bacterial prey of A. incarcerata.