2021 Volume 70 Issue 9 Pages 535-540
We have estimated the effect of a chemical reagent based on the oxygen consumption and the motion of zebrafish embryos by using an LSI-based amperometric sensor array device (Bio-LSI). Bio-LSI with 400 gold microelectrodes in a 6 mm × 6 mm region enabled us to visualize the distribution of the concentration of redox species as images. We applied –0.2 V vs. Ag/AgCl to all electrodes of a Bio-LSI chip to obtain the distribution of the oxygen concentrations in the presence of zebrafish embryos. The motions of the embryos were observed and traced by a CMOS camera. The reduction currents, obtained at the electrodes immediately under the embryos, are smaller than that obtained at the electrodes without the embryos. When the embryos moved to the position above other electrodes, the positions of electrodes with the low reduction current synchronized to the position of the embryos. This was due to the consumption of oxygen by the respiration of embryos and the inhibition of the diffusion of oxygen to the electrodes. When a solution containing 2,4-dinitrophenol (DNP), that is an uncoupler of oxidative phosphorylation, was added, the reduction current drastically decreased and then gradually returned to the original level. The active motions of the embryos coupled with the decrease of the reduction current were observed immediately after adding DNP, while no motion was observed after turning toward original level. Embryos would transiently enhance the consumption of oxygen by respiration due to the compensation of its depression of ATP synthesis, and then be led to death. The present system based on the reduction currents of oxygen and the motions of embryos would provide simple and high-throughput toxicity tests for various chemical agents.
