Inhibition of conjugation in Tetrahymena pyriformis by cerulenin. Possible requirement for de novo lipid synthesis.

Conjugation in Tetrahymena pyriformis is induced by the mixing of two starved complementary mating types. Addition of the antibiotic cerulenin, a specific inhibitor of de novo lipid synthesis, upon mixing of the mating types inhibited the conjugation process. The inhibition of conjugation was found to be reversible upon washing the cells. Cerulenin inhibited [14C]acetate incorporation into the lipid fraction of the cells, while it did not affect the incorporation of [3H]leucine into proteins. Analysis of the fatty acid composition of the whole cells revealed that during conjugation the ratio of saturated to unsaturated fatty acids is markedly changed. While the ratio of saturated:unsaturated fatty acids is 0.30 in unconjugated cells, it reached a value of 0.45 in conjugated cells.