Biophysics and Beyond

The effect of ultraviolet-B (UV-B) radiation and nanoparticles as stress factors on the plasma membrane of leaf cells of the aquatic plant Elodea canadensis was investigated using the microelectrode method. In Elodea cells exposed to UV radiation in a white light background, a rapid and reversible depolarization of the membrane potential followed by a slow depolarization phase was observed. A monotonic change in membrane potential with serial impulses of UV-B for 15 seconds and a dark interval of 3 minutes was noted. The spectrum of the action of fast UV-B radiation is in the range of 300-330 nm, while the slow phase is in the range of 280-300 nm. Nanoparticles interact with the H-ATPase electrogenic proton pump and redox system in the plasma membrane of plant cells, potentially causing structural and functional damage. It has been proven that in green cells of plants, there are two types of photon-carrying electrogenic pumps in the plasma membrane: the redox-active H⁺-pump and the H⁺-ATPase enzyme complex. When leaf cells are exposed to UV light, the redox-active H⁺-pump is first inhibited, followed by the H⁺-ATPase. It is suggested that the primary chromophore of UV-B light in the plasma membrane may be one of the components of the redox-active H⁺-pump.