Electron-microscopic evidence showing the location of strontium and calcium deposits on the lamellae of spinach chloroplasts is presented. The chloroplast limiting membrane did not act as a barrier for this ion accumulation, since the chloroplasts were ruptured during the isolation and incubation, especially in the light. The grana stacks also were extensively swollen. The number of electrondense deposits attached on the lamellae was greatly increased by light under conditions favoring the hydrolysis of ATP. The average diameter of the deposits after a 6 minute illumination with 1 mM SrCl2 was 14 mμ, after 15 minutes with 1 mM SrCl2 was 21 mμ, and after 15 minutes with 20 μM SrCl2 was 13 mμ. The findings are in harmony with the results of ion-uptake experiments using radioactive strontium and calcium.
No takes yet. Share an insight, caveat, or question.
Nobel et al. (1966) studied this question.