PRE-PAIRING EVENTS IN TETRAHYMENA-THERMOPHILA - ANALYSIS OF BLOCKS IMPOSED BY HIGH-CONCENTRATIONS OF TRIS-CL

Initiation, a process that occurs at the very onset of the sexual cycle in the ciliate Tetrahymena thermophila, is blocked by concentrations of Tris-Cl in excess of 50 mM. Cells starved in 60 mM Tris-Cl proceed through the first 30 min of initiation before arresting. Cells allowed to initiate for 15-45 min in 10 mM Tris-Cl before exposure to 60 mM Tris-Cl accumulate at a second point about 50 min through the process. Two variants which behave differently than wild type in 60 mM Tris-Cl are described. A model for initiation is proposed and its implications are discussed. © 1979.