INCORPORATION OF RADIOACTIVE CARBON FROM H14CO3-INTO SUGAR CONSTITUENTS BY A BROWN ALGA, EISENIA BICYCLIS, DURING PHOTOSYNTHESIS AND ITS FATE IN THE DARK

When the fronds of Eisenia bicyclis were exposed to H¹⁴CO₃^–in the light, the radioactive carbon was rapidly incorporatedinto mannitol. Even after illumination of such a short periodas 5 min, about seventy percent of the total radioactivity incorporatedwas found in this compound, and the specific radioactivity ofthis alcohol decreased very rapidly during the subsequent darkincubation. Among various cellular polysaccharides examined,only laminaran showed a similar quick response with respectto the specific radioactivity change. On the basis of thesefindings it was concluded that mannitol and laminaran form storagesubstances in the brown alga, and they are possibly interchangeableas sucrose and starch do in higher plants. ¹This work was partly reported at the 27th Annual Meeting ofthe Botanical Society of Japan, Nagoya, 1962, and at the 28thAnnual Meeting of the Botanical Society of Japan, Okayama, 1963. ²Contribution from the Shimoda Marine Biological Station, TokyoKyoiku University, No. 149.