| Popis: |
Summary The artificial electron acceptors, potassium ferricyanide and tetrahiafulvalene cation radical, are shown to inhibit uptakes of chloride, nitrate and sulphate anions in the green fresh-water alga Hydrodictyon reticulatum . The same is true about the phosphate anion in an alkaline medium, where its divalent form prevails. The unidirectional efflux of these anions was not inhibited. TTF + , the more potent of the two inhibitors, appears to be partly located in the plasma membrane. An electron-anion antiport (a redox pump) is suggested as the mechanism of the active uptake of most of the physiologically important anions in the alga. Notable exceptions to this rule are represented by bicarbonate, the carbon source for photosynthesis at air levels of CO 2 , and by phosphate (probably univalent) in a medium buffered to pH6. |
