Periodicity of endocytosis inTetrahymena pyriformis

Summary

Starved cells ofTetrahymena pyriformis show marked periodicity in the rates of uptake of digestive vacuoles when presented with a mixture of peptone and polystyrene latex particles. Rates of egestion also show some periodicity. The results show that the supply of membrane is not the sole factor (and possibly not even a main factor) restricting vacuolar uptake. The rates of egestion also do not appear to be greatly influenced by the amounts of digestive vacuole membrane to be reincorporated into the cell membrane. It is suggested that energy and lysosomal supplies may be more important than membrane supply for uptake and that reduction in the supply of uncombined lysosomes may in some way cause cessation of vacuole formation.

Fed cells ofTetrahymena also show variations in the rate of digestive vacuolar uptake with time. The maximum rate of uptake is about three times as great as that found in starved cells.