carbon dioxide dependence of ATPase activity Algal CO2 Transport.
Eremosphaera viridis is an acidophilic algae which actively takes up carbon dioxide during photosynthesis. The mechanism is not well known, but bicarbonate transport does not occur, and the uptake can't be due to carbon dioxide diffusion across the plasma membrane, because the energetics won't work. Surprisingly, the membranes exhibit a CO2-activated ATPase. Half-maximal stimulation of ATPase activity is very similar to half-maximal carbon dioxide uptake by whole cells. Thus, carbon dioxide uptake may be mediated by a CO2 ATPase.

Images.Eremosphaera viridis Right: mitochondria (green) and chloroplasts (red) in optical sections (top to bottom: medial to surface focal planes) in a single cell of Eremosphaera viridis

Eremosphaera viridis in culture [png format]. Animated gif optical slices ([brightfield] and ([chloroplast fluorescence])


Images. Below: Eremosphaera viridis Systrophe Eremosphaera systrophe

Images. Below: Eremosphaera viridis Fluorescence Z-section (chloroplasts and membranes) Eremosphaera fluorescence