A STUDY OF RADIOPHOSPHATE UPTAKE IN PARAMECIUM MULTIMICRONUCLEATUM

¹ Dept. of Invertebrate Zoology and Entomology, University of Utah, Salt Lake City 1, Utah

1. In a medium containing inorganic radioactive phosphorus, Paramecium multimicronucleatum become sufficiently radioactive for use in quantitative predation experiments.

2. It is possible to measure the P³² uptake of a single individual.

3. When food is absent, Paramecium does not take in inorganic phosphate in solution. The phosphate is acquired in measurable amounts in its food.

4. The phosphate taken in is rapidly lost from the animals, probably as a result of an organic turnover.

5. Paramecia in old cultures, especially cultpres containing Chlorella, become more radioactive than those in other cultures probably because the Chlorella which are ingested by the paramecia, absorb much phosphate, and also because old cultures of paramecia are primarily non-dividing.

6. The greater the initial concentration of P³² in solution, the more radioactive the paramecia become.

7. When washed by centrifugation, there is a leakage of P³² from the organisms over and above the normal turnover of phosphate.