THE EFFECT OF TEMPERATURE SHIFTS ON THE INTRACELLULAR LEVEL OF NUCLEOSIDE TRIPHOSPHATES IN TETRAHYMENA PYRIFORMIS

Abstract

Mass cultures of Tetrahytnena pyriformis GL were subjected to seven cyclic changes in incubation temperature to induce synchronized division. Cultures were sampled before, during, and after exposure to the treatment. Acid extracts were assayed for their nucleoside triphosphate and protein content. It was found that the NTP/protein ratios decreased as a result of each heat shock (34 °C) by an average of 22%, while each subsequent period at optimum incubation temperature (29 °C) resulted in an average increase in the NTP/protein ratio of 36% above the initial value. During the final recovery period of 80 minutes between the last heat shock and the first synchronized division, a significant increase in the NTP/protein ratio was observed.The results are discussed in connection with the problem of the energy requirements for cell division.