Imaging of Photosynthetic and Respiratory Activities of a Single Algal Protoplast by Scanning Electrochemical Microscopy

Scanning electrochemical microscopy (SECM) based on the reduction current for oxygen was used for imaging of respiratory and photosynthetic activities of single, living protoplasts. In the dark, the image of the protoplast appeared as a spot with lower oxygen concentration due to consumption of oxygen by respiration. Under light irradiation, the protoplast appeared as the opposite image because it generated oxygen by photosynthesis. SECM images clearly displayed a decrease in photosynthetic activity of the protoplast injected with 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU), a photosynthetic inhibitor.