Inner structure of intact chloroplasts observed by a low temperature laserscanning microscope

Inner structure of isolated intact chloroplasts was observed for the first time by a method of laser scanning microscopy at the temperature of liquid nitrogen at 77 K. The microscope, based on gradient index optics, has a max imum resolution of 440 nm at the wavelength of 650 nm. Chloroplasts were ex cited into the Q-band of chlorophyll b by a krypton laser line at 647.6 nm and fluorescence was detected using two different interference filters. The 680 nm interference filter detects the regions where photosystem (PS) 2 ma inly occurs, the 730 nm interference filter detects domains with predominan t location of PS1. Since PS1 occurs mainly in stroma lamellae, whereas PS2 occurs mainly in grana regions we were able to view the structure of thylak oid membrane in isolated intact chloroplast that is the closest to in vivo state.