Temporal pattern of macromolecular events during the microstome-macrostome cell transformation of Tetrahymena vorax strain V2S

Differentiation of cell type can be experimentally controlled in the ciliated protozoan Tetrahymena vorax. If an early stationary growth phase population of small‐mouthed saprozoic cells (called microstomes) is washed and suspended in a transforming principle, stomatin, (which is released by a potential prey, i.e., Tetrahymena pyriformis), the microstomes transform into a population of large‐mouthed potentially carnivorous cells (called macrostomes). This process is observed by four and one‐half hours after stomatin addition. During cell transformation the pattern of DNA, RNA and protein synthesis were measured by autoradiographic and chemical techniques. Microstomes undergo macrostome formation with a net synthesis of cellular protein and RNA. Autoradiographs demonstrate that no new cells enter DNA synthesis during the first four hours of cell transformation. Isotope labeling and chemical data demonstrate that RNA synthesis is stimulated by stomatin and reaches a peak at about 150 minutes; increased protein synthesis lags somewhat behind RNA synthesis and does not reach a peak until 210 minutes. The increased synthesis of RNA and protein is associated with disaggragation of fused nucleoli into individual nucleoli. The disaggregation of fused nucleoli and the associated increases in RNA and protein synthesis appear necessary for the ensuing morphogenetic events which lead to macrostome formation. Apparently stomatin is serving as a relatively rich source of nutrient.