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.
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])
![[png format]](images/viridis_culture.png){kind=link}
![[brightfield]](images/viridis_03_brightfield.gif){kind=link}
![[chloroplast fluorescence]](images/viridis_03_fluor.gif){kind=link}
Publications
- Lew RR (2010) Ion and oxygen fluxes in the unicellular alga Eremosphaera viridis. Plant and Cell Physiology 51:1889-1899. [pubmed]
- Deveau JST, RR Lew and B Colman (2001) Evidence for active CO2 uptake by a CO2-ATPase in the acidophilic green alga Eremosphaera viridis. Canadian Journal of Botany. 79:1274-1281. [link to abstract]
- Deveau JST, H Khosravani, RR Lew and B Colman (1998) The CO2 uptake mechanism in Eremosphaera viridis. Canadian Journal of Botany. 76:1161-1164. [link to abstract]
- Rotatore C, RR Lew and B Colman (1992) Active uptake of CO2 during photosynthesis in the green alga Eremosphaera viridis is mediated by a CO2-ATPase. Planta. 188:539-545. [pubmed]
Images. Below: Eremosphaera viridis Systrophe
Images. Below: Eremosphaera viridis Fluorescence Z-section (chloroplasts and membranes)
