Effect of Salts and Electron Transport on the Conformation of Isolated Chloroplasts. II. Electron Microscopy

Publisher Website
Google Scholar
Abstract
Spinach chloroplasts isolated in media containing salts and chloroplasts which are still within their envelopes retain grana similar to those seen in chloroplasts in situ. Chloroplasts isolated in low-salt media lost their grana without losing any chlorophyll. The lamellae in the low-salt media consisted of continuous sheets loosely held to other lamellae by tenuous material which did not stain with permanganate. Addition of salts to the grana-free, low-salt chloroplasts resulted in a stacking of lamellae which was sometimes almost random, but sometimes resulted in regular structures indistinguishable from the original grana. The rapid electron transport (Hill reaction) made possible by atebrin-uncoupling was associated with a collapsing together of the otherwise widely separated lamellar membrane pairs. The much slower electron transport which occurred in the absence of uncouplers was associated with a similar but smaller decrease in the space between the lamellar membrane pairs. The chloroplast swelling which occurred during amine-uncoupled electron transport was associated with gross distortion of the lamellae.