Plant and Cell Physiology, 1985, Vol. 26, No. 2 245-252
© 1985
Article |
Ammonia Induces Starch Degradation in Chlorella Cells
1 Radioisotope Centre, University of Tokyo Bunkyo-ku, Tokyo 113, Japan
2 Institute of Applied Microbiology, University of Tokyo Bunkyo-ku, Tokyo 113, Japan
When ammonia was added to cells of Chlorella which had fixed 14CO2 photo synthetically, 14C which had been incorporated into starch was greatly decreased. A similar effect was observed when potassium nitrate and sodium nitrite were added. The ammonia-induced decrease in 14C-starch was observed in all species of Chlorella tested. With cells of C. vulgaris 11h, most of the radioactivity in starch was recovered in sucrose, indicating that ammonia induces the conversion of starch into sucrose. The percent of 14C recovered in sucrose differed from species to species and practically no recovery in sucrose was observed in C. pyrenoidosa. In most species tested, the enhancing effects of blue light and ammonia on O2 uptake as well as the ammonia effect on starch degradation were greater in cells which had been starved in phosphate medium in the dark than in non-starved cells. In contrast, the enhancing effect of ammonia on dark CO2 fixation was much greater in non-starved cells. C. pyrenoidosa was unique in that blue light did not show any effect on its O2 uptake.
(Received August 15, 1984; Accepted November 16, 1984)
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