Transformation in Tetrahymena pyriformis: Description of an Inducible Phenotype*†

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Abstract
Transformation of T. pyriformis to a rapid-swimming (presumably dispersal) form can be induced by washing cells and suspending them in distilled H2O, Dryl''s solution or 10 mM Tris. Transformation is possible with high efficiency in mass cultures of axenically grown cells within .apprx. 5 h at 30.degree. C. The radically different phenotype produced during transformation is characterized by a more elongate body form, increased numbers of somatic basal bodies and cilia, a long caudal cilium and oral membranelles positioned beneath the cell surface. DNA quantities characteristic of G1, S and G2 cells are found in these transformed ciliates, suggesting that achievement of a particular stage in the DNA-division cycle is not a prerequisite for transformation. Preliminary observations on cells belonging to syngens 2-12 indicate that they have a capacity to form a caudal cilium, but the amicronucleate strain GL-C does not. Possible relevance of the transformed phenotype for taxonomy of Tetrahymena is discussed.