Photosynthetic bicarbonate utilization in the aquatic angiospermsPotamogeton andElodea

Prins, H. B. A.; Snel, J.; Helder, R. J.; Zanstra, Pieter E.

doi:10.1007/bf02284741

Cited by 24 publications

(15 citation statements)

References 10 publications

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“…However, the above approach does not take into consideration the possibility that an acidic unstirred layer might exist around the cell, even in alkaline media, due to the activity of the outwardly directed H + pump (Spanswick, 1981). This has prompted several groups to suggest that in this locally acidic region, the molecular CO2 concentration may be significantly higher than that estimated from measurements in the bulk medium, and that in reality, aquatic angiosperms and Characean algae may not have the capability to transport HCO~- (Prins et al, 1979(Prins et al, , 1980(Prins et al, , 1982Ferrier, 1980;Walker et al, 1980). Two independent attempts to quantify these ideas have led to the notion that the pH at the membrane (cell surface) should be about 6.0 or lower in order to attain the observed rates of l~C-fixation in media of bulk pH 8.2 or above (Ferrier, 1980;Walker et al, 1980).…”

Section: Introductionmentioning

confidence: 92%

Bicarbonate transport inChara corallina: evidence for cotransport of HCO 3 − with H+

1983

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Summary. Experiments were undertaken on the fresh water algaChara eorallina to determine the form of inorganic carbon (CO2 or HCO;-) which enters the cell during photosynthesis at alkaline pH. Recent proposals have centered on the possibility that proton efflux in alkaline solution is able to generate, in the immediate vicinity of the cell, a sufficiently low pH to raise the partial pressure of CO z, and hence facilitate its passive permeation into the cell. Ferrier, 1980, Plant Physiol. 66:1198-1199), and these were tested by placing recessed-tip pH microelectrodes in the unstirred layer surrounding cells in stagnant solution (bulk pH 8.2, buffered only with I mM HCO3). Even as close as 2 gm from the cell wall, the pH was typically 7.2 to 7.6 in the acid band center -over 1 pH unit greater than that suggested by the models for CO2 entry at the necessary rate for C-fixation. Further evidence for the entry of HCO;-, rather than CO2, at high solution pH was obtained from experiments in which the radial pH gradient in the unstirred layer was reduced. Buffer solutions containing 5 mM phosphate or 5 m~ HEPES, raised the pH at the cell surface in the acid regions from around 7.2 to 7.8 or higher. This pH increase (reduction in acid gradient) would have greatly reduced the COz level at the cell surface and should, therefore, have greatly reduced the CO2-related 14C-influx. However, 14C-fixation was reduced by only 31% (phosphate) or 15% (HEPES), compared with buffer-free controls. Reduction of the unstirred layer thickness by fast solution flow resulted in a stimulation, and not a reduction, of l~C-fixation. The similarity of our radial pH profiles near the wall with that predicted by the model assuming H +-HCO 3 cotransport, together with the effects of buffer, and the results of increased solution flow rate, lead to the conclusion that cotransport of HCO~-with H + is the likely method of entry of inorganic carbon. Longitudinal pH profiles of the Chara cell were obtained at a distance of 25 I-tin from the wall. These revealed much sharper delineation of the acid and alkaline bands than has previously been possible with miniature pH electrodes. Profiles of local electric field, obtained with a vibrating probe, were in excellent agreement with the high resolution pH profiles. This supports the hypothesis that membrane proton transport has a role (direct) in the generation of the extracellular currents.

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Section: Introductionmentioning

confidence: 92%

Bicarbonate transport inChara corallina: evidence for cotransport of HCO 3 − with H+

1983

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“…In TH, pH of the water layer increased from 7.5 to 9-9.5 during the growing season, which was strongly correlated to temperature (results not shown) as a result of photosynthetic activity of the aquatic vegetation (uptake of carbon dioxide and bicarbonate; Prins et al 1979;Søndergaard 1988). PO binding is reduced by this rise in pH (Patrick 3Ϫ 4 et al 1973).…”

mentioning

confidence: 96%

Factors controlling the extent of eutrophication and toxicity in sulfate‐polluted freshwater wetlands

Lamers

Falla

Samborska

et al. 2002

Limnology & Oceanography

125

105

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Increased sulfur loads originating from polluted surface water and groundwater, and from enhanced atmospheric input, are a major threat to the biogeochemical functioning and biodiversity of freshwater wetlands. Sulfate reduction, normally playing a modest role in these systems, becomes the most important biogeochemical process, inducing severe eutrophication and sulfide toxicity. In field enclosure experiments we observed striking differences between the responses of two freshwater marshes to sulfate. On one location sulfate addition resulted in strong phosphorus mobilization without sulfide accumulation, whereas high sediment sulfide concentrations, known to be toxic to wetland macrophytes, were reached in the other marsh without eutrophication occurring. The results could be explained by differences in groundwater iron discharge and nutrient contents of the peat sediments. Sulfate reduction rates appeared to be limited by either electron donor availability (first marsh) or electron acceptor availability (second marsh). The implications of these findings are explained in relation to freshwater wetland management.

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“…K^. O2 and reference electrodes, there just touching the leaf surface as described previously (Prins et al, 1979(Prins et al, , 1980a, The experimental set-up is schematically depicted in Fig, 1, A closed perspex experimental chamber was used except in those experiments where the O2 concentration was also measured. The experimental solution contained 1 mol m"^KHCO3 + l mol m"^ KCI.…”

Section: Methodsmentioning

confidence: 99%

“…Figure 2 shows the effect of light on the surface pH's and the O2 concentration tiear an Elodea leaf. The pH changes were described previously in detail (Prins et at., 1979(Prins et at., , 1980a, therefore a short description suffices here. In the dark the pH at both sides was somewhat below that of the medium due to respiratory CO2 production.…”

Section: MMmentioning

confidence: 99%

“…Generally it has been assumed that HCO," is transported across the plasmalemma into the cytoplasm where it equilibrates with CO2, thus making CO2 available for photosynthesis. However, we have suggested earlier that CO2 (CO2 = CO2 in its molecular form including H2CO3, unless otherwise stated), and not HCOf, is the permeant species and that HCOJ is extracellulaiiy converted into CO2 by the activity of H"^ pumps located at the plasmalemma ofthe lower cells of Elodea and Potamogeton (Prins et al, 1979(Prins et al, , 1980aPrins & Helder, 1980;Prins, Snel & Zanstra, 1981a). Recently a comparable mechanism has been suggested for the charophytes (Ferrier, 1980;Walker, Smith & Cathers, 1980), Photosynthetic use of HCOjis accompanied by a pH drop near the lower epidermis of the polar angiosperms and in the acid bands of Cluira (Ferrier, 1980;Lucas & Smith, 1973;Lucas.…”

Section: Introductionmentioning

confidence: 99%

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The mechanism of bicarbonate assimilation by the polar leaves of Potamogeton and Elodea. CO₂ concentrations at the leaf surface

Prins

Snel

Zanstra

et al. 1982

Plant Cell & Environment

Self Cite

113

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Photosynthetic utilization of HCO, in leaves of Pot(tmogeton and Elodea occurs at the lower leaf side, with subsequent OH~ release at the upper side. It is accompanied by transport of cations, in the present experiment K^, across the leaf. The resulting pH and K"^ concentration changes near the leaf surface were recorded with miniature electrodes. From the pH and K^ concentration the concentrations of the different inorganic carbon species were calculated and compared with photosynthetic O2 production, HCO3' utilization is accompanied by a drastic increase in the free CO2 concentration near the lower epidermis. Experiments with CO2-and HCO3"-free solutions showed an oscillating acidification near the lower epidermis and alkalinization near the upper epidermis. It is concluded that the acidification results from the activity of light-dependent H"^ pumps. The finding that an increase in pH at the upper side always coincided with a decrease at the lower in these experiments shows that the H ^ pumps and the OH " extruding mechanism are coupled although occurring in different cell layers. Previously we have suggested that the first step in the process of photosynthetic HCO.^ utilization is external conversion of HCO3" by acidification caused by light-dependent H^ pumps. The present results strongly support this hypothesis. Two possible pathways for the accompanying Kt ransport are discussed. The model presented here explains the known inhibiting effects of buffers and high pH on photosynthetic HCO^ utilization.

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Photosynthetic bicarbonate utilization in the aquatic angiospermsPotamogeton andElodea

Cited by 24 publications

References 10 publications

Bicarbonate transport inChara corallina: evidence for cotransport of HCO 3 − with H+

Bicarbonate transport inChara corallina: evidence for cotransport of HCO 3 − with H+

Factors controlling the extent of eutrophication and toxicity in sulfate‐polluted freshwater wetlands

The mechanism of bicarbonate assimilation by the polar leaves of Potamogeton and Elodea. CO₂ concentrations at the leaf surface

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Photosynthetic bicarbonate utilization in the aquatic angiospermsPotamogeton andElodea

Cited by 24 publications

References 10 publications

Bicarbonate transport inChara corallina: evidence for cotransport of HCO 3 − with H+

Bicarbonate transport inChara corallina: evidence for cotransport of HCO 3 − with H+

Factors controlling the extent of eutrophication and toxicity in sulfate‐polluted freshwater wetlands

The mechanism of bicarbonate assimilation by the polar leaves of Potamogeton and Elodea. CO2 concentrations at the leaf surface

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The mechanism of bicarbonate assimilation by the polar leaves of Potamogeton and Elodea. CO₂ concentrations at the leaf surface