The division site in both chloroplasts and bacteria is established by the medial placement of the FtsZ ring, a process that is in part regulated by the evolutionarily conserved components of the Min system. We recently showed that mechanosensitive ion channels influence FtsZ ring assembly in both Arabidopsis thaliana chloroplasts and in Escherichia coli; in chloroplasts they do so through the s...

A method was found for the in situ activation of the latent Ca(2+)-ATPase of the coupling factor from chloroplasts of Euglena gracilis and its resultant solubilization. The activation causes the concomitant solubilization of the enzyme and facilitates easy and nearly complete extraction. The activation consists of lowering the pH of isolated chloroplasts for 2 minutes to pH 4.5 to 4.7 with acet...

It was shown by Cranes that plastoquinone is localized in the chloroplasts of higher plants, and there is now a good deal of evidence which suggests that it bctions as an oxidation-reduction carrier in the photosynthetic electron transport system. Bishop’ showed that when lyophilized chloroplasts were extracted with organic solvents they lost their Hill-reaction activity, but that this could be...

Ammonium toxicity resulted in morphological modifications of tomato leaf chloroplasts. The chloroplasts, which are normally flattened around the protoplast periphery, became ellipsoidally rounded and dispersed through the protoplasm. The first apparent effect of plastid degradation was development of many vesicles from the fretwork. Later the grana lamellae swelled, and some disappeared. Eventu...

A lipid requirement for photosystem I activity in Spinacia oleracea chloroplasts has been characterized. The transfer of electrons from tetramethyl-p-phenylenediamine through the chloroplast photosystem to viologen dye was used as an assay of photosystem I activity. Activity is diminished by prolonged heptane extraction and is partially restored by readdition of the extracted lipid. Extracted c...