| Abstract: | SYNOPSIS. Supplementation of a chemically-defined medium that supported excellent axenic growth of Tetrahymena pyriformis, mating type II, variety 1, at 35 C, with nucleic acid derivatives allowed full growth at 37, and further addition of phospholipids permitted equivalent growth at 39 and 1/3 of that at 40. No other nutrients tested were active at 40. Population growth could be sustained continuously by serial sub-culture every 48 hr at 40 only if the medium contained synthetic phospholipids or phospholipids isolated from natural sources. The requirement was specific for phosphatidyl choline and phosphatidyl ethanolamine. Phospholipids which contained only saturated fatty acids, and ones which contained unsaturated acids were active. Phospholipids and neutral lipids isolated from 35-grown T. pyriformis were also effective. Phospholipid precursors, sterols, neutral lipids and fatty acids were not. A 48–72 hr exposure to 40 in either the unsupplemented medium or the nucleic acid derivatives-phospholipid-supplemented medium caused extreme variation in size and shape, fractured and displaced kineties, and abnormalities of karyokinesis. The frequency and degree of teratology was greater in the unsupplemented medium, but not markedly so. A possible metabolic basis for the temperature-induced phospholipid requirement and the morphological abnormalities is discussed. |
