| Range |
Table - link
|
| Organism |
Diatoms |
| Reference |
Hopkinson BM, Dupont CL, Allen AE, Morel FM. Efficiency of the CO2-concentrating mechanism of diatoms. Proc Natl Acad Sci U S A. 2011 Mar 8 108(10):3830-7. doi: 10.1073/pnas.1018062108 p.6 table 3PubMed ID21321195
|
| Method |
P.1 right column 3rd paragraph: "The bulk of [investigators’] experiments consist of time courses of 18O depletion from labeled inorganic carbon, a process catalyzed by the presence of the enzyme carbonic anhydrase (CA) in cells. CA, which catalyzes the hydration of CO2 and dehydration of HCO3−, plays critical roles in CCMs [CO(2) concentrating mechanisms] and is present in all [their] experimental organisms: Thalassiosira weissflogii, T. pseudonana, T. oceanica, and Phaedactylum tricornutum, (SI Text, Experimental Organisms)." |
| Comments |
P.5 left column bottom paragraph: "In contrast, models that consider active CO2 transport into the cytoplasm, vectorial CA (Carbonic Anhydrase) activity, or DIC (Dissolved inorganic carbon) transport into the chloroplast provide acceptable fits to experimental data and could, in principle, explain the 18O depletion caused by light (Fig. 6 C–F). However, these various processes have widely different energetic costs, and they result in widely different concentrations of CO2 in the chloroplast, the raison-d’être of the CCM (Table 3). Vectorial CA activity and CO2 transport into the cytoplasm are similar processes, because the active conversion of CO2 to HCO3− in the cytoplasm creates an inward CO2 gradient driving diffusive CO2 influx. However, neither process elevates the CO2 concentration in the chloroplast much above extracellular levels (Table 3), and vectorial CA activity requires an unreasonable energetic expenditure." |
| Entered by |
Uri M |
| ID |
116875 |