Tetrahymena cell cycle, synchronization

Since the first publication of the heat shock method of division synchronization of Tetrahymena there has been a steady stream of reports dealing with the system. Many investigators have used the system as first intended, for the chemical analysis of the cell cycle. Others, among them the writer, have taken more interest in problems that concern mechanisms by which the heat shocks force into good synchrony cells that had previously divided over a spread of time equal to the duration of a full cell generation. There is as yet no final explanation of this phenomenon, but there are interpretations based on many experiments, and these are dealt with in this chapter. 

The role of calcium in cell division is controversial. The measurement of cation fluxes in synchronized cultures of Tetrahymena shows an influx of calcium 30 minutes prior to the initiation of cell division.440 However, there is also an influx of magnesium, and it has been suggested441 that the fluctuation of these metals during the synchronized division cycle is an effect rather than a cause. 

Padilla, G. M., and I. L. Cameron. 1964. Synchronization of cell division in Tetrahymena pyriformis by a repetitive temperature cycle. J. Cell. Comp. Physiol., 64 303-308. 

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