Study of the distribution and biological effects of 3H in the algae Acetabularia, Chlamydomonas and Porphyra.

Freshwater and marine algae are particularly useful for studying the radioactive contamination of aquatic systems. Acetabularia, Chlamydomonas and Porphyra were used to investigate the uptake and eventual biological effects of tritium. When the Acetabularia are grown in the presence of tritiated water, a significant amount of 3H is incorporated in the total nucleic acids and protein fraction. Chloroplasts of Acetabularia were isolated from whole cells and their DNA purified by the agarose procedure, before radioactivity analysis: a significant amount of 3H was incorporated into the chloroplast genome. Chlamydomonas was grown on minimal medium containing increasing concentrations of tritiated water. The increase in cell number was checked by microscope counting. The generation time was 9.6 h and seemed not affected even by the highest 3H concentration. Parallel experiments have shown that an appreciable amount of 3H was incorporated into the total organic matter of the plants. In the case of Porphyra, it was found that a very low level of 3H was incorporated into the total DNA of the plant.