Photosynthetic oscillation in individual cells of the marine diatom Coscinodiscus wailesii (Bacillariophyceae) revealed by microsensor measurements

Oscillations with a period of 1-2 min in the rate of photosynthesis have been found in leaves of C-3 and C-4 land plants under invariant, saturating, light and carbon dioxide. This article reports the occurrence of similar oscillations with a period of 2-2.5 min in individual cells of the marine diatom Coscinodiscus wailesii. These oscillations were determined by measurements of both oxygen (oxygen microelectrode) and carbon dioxide (pH microelectrode) just outside the plasmalemma. These oscillations were found in less than 1% of the cells examined. The occurrence of oscillations in unicelluar diatoms rules out for these organisms hypotheses as to the origin of oscillations in land plant leaves that are based on cell-cell interactions.