Effect of light intensity on sulfate uptake and primary productivity by natural freshwater microplankton communities and axenic algal cultures

Monheimer, Richard H.

doi:10.1007/bf00006118

Cited by 2 publications

(1 citation statement)

References 9 publications

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“…We postulated that silver could cross biological membranes as the silver-thiosulfate complex, via an anion transporter, and set out to test this "molecular mimicry" hypothesis (12) using a unicellular alga as our biological model. Since algae are known to possess membrane-bound transport systems for the assimilation of sulfate (13,14), they should be appropriate models for testing the hypothesis that thiosulfate (and silver-thiosulfate complexes) can mimic sulfate and enter the cells via the same pathway (15).…”

Section: Introductionmentioning

confidence: 99%

Thiosulfate Enhances Silver Uptake by a Green Alga: Role of Anion Transporters in Metal Uptake

Fortin

Campbell

2001

Environ. Sci. Technol.

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Short-term (< 1 h) silver uptake by the green alga Chlamydomonas reinhardtii was measured in the laboratory in defined inorganic media in the presence or absence of ligands (chloride and thiosulfate). In contradiction to the free-ion model of metal uptake, silver accumulation by the alga proved to be sensitive to the choice of ligand used to buffer the free silver concentration. For a low fixed free Ag+ concentration of 10 nM, silver uptake in the presence of thiosulfate (0.11 microM) was 2x greater than in the presence of chloride (4 mM). When sulfate was removed from the exposure medium (i.e., 81 microM-->0 microM), silver uptake in the presence of thiosulfate was even more markedly enhanced (more than 4x greater than in the presence of chloride). Varying the sulfate concentration in the exposure medium only affected silver uptake if thiosulfate was present. We conclude that silver-thiosulfate complexes are transported across the plasma membrane via sulfate/thiosulfate transport systems and that sulfate acts as a competitive inhibitor of this uptake mechanism.

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Section: Introductionmentioning

confidence: 99%

Thiosulfate Enhances Silver Uptake by a Green Alga: Role of Anion Transporters in Metal Uptake

Fortin

Campbell

2001

Environ. Sci. Technol.

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Particulate organic sulfur in the waters of the Southern California Bight

Matrai¹,

Eppley²

1989

Global Biogeochemical Cycles

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The organic sulfur content of suspended and sinking particulate matter was examined in the upper 1000 m of the water column in the Southern California Bight. Depth distributions of suspended particulate organic sulfur (POS) showed a subsurface maximum in most stations that deepened offshore. POS concentrations in suspended matter averaged 1.26 ± 0.50 μg S L−1 within the euphotic zone during the two cruises analyzed (August and October, 1987). The downward fluxes of mass, carbon, nitrogen and sulfur of sinking particulate matter increased with increasing sample depth to 350 m in the water column. Fluxes were similar during the three deployments. POS was correlated with and directly proportional to POC, PON, and chlorophyll a in the suspended material. Similar correlations were obtained in the trap material although a positive POC intercept value suggested the presence of more refractory material, with sulfur being selectively removed relative to carbon. The average molar ratios were C : N : S = 224 : 27: 1 in suspended and 119 : 17 : 1 in sinking particulate organic matter. Particulate organic sulfur appeared to have a biological origin, most likely planktonic.

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Effect of light intensity on sulfate uptake and primary productivity by natural freshwater microplankton communities and axenic algal cultures

Abstract: Analyses of four years of in situ sulfate uptake by microplankton communities in two trophically different lakes showed that about 12% of the experiments had dark uptake equal to or higher than uptake at ambient light.

Cited by 2 publications

References 9 publications

Thiosulfate Enhances Silver Uptake by a Green Alga: Role of Anion Transporters in Metal Uptake

Thiosulfate Enhances Silver Uptake by a Green Alga: Role of Anion Transporters in Metal Uptake

Particulate organic sulfur in the waters of the Southern California Bight

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