2020 年 59 巻 1 号 p. 189-195
For the present study we tried to visualize the formation of aqueous Cu2+ ion induced reactive oxygen species （ROS） and subsequent damage to cell components in Synechococcus elongatus PCC 7942 （S. elongatus） cells, either in the presence or absence of Zn2+ and Ni2+ ions. Metal ion ratios in aqueous solutions were prepared by simulating the metal compositions of five different standard alloys including pure Cu, Brass （C2600）, Brass （C2680）, Nickel Silver （C7521） and Nickel Silver （C7701）. Live images of interactions of cyanobacteria cells with different metal ion solutions were taken by fluorescent microscope equipped with a multicolor time lapse recording system. Ultrastructural changes were observed by transmission electron microscope （TEM）. ROS, DNA and chlorophyll fluorescence of cyanobacteria cells were dynamic over time and remarkably diverse depending on the aqueous metal ion compositions. In contact with Cu2+ ions alone, cyanobacteria gained an extreme level of ROS while DNA fluorescence rapidly disappeared. Presence of Zn2+ ions prevented the DNA fluorescence disappearance caused by Cu2+ ions and abolished adverse effects induced by ROS synthesis. Addition of Ni2+ ions caused distinct chlorophyll fluorescence reduction. Ultrastructural observations showed severe damage to the cytoplasm, thylakoid membranes and carboxysomes after interaction with all tested aqueous metal ion combinations.
