Toxicity of silver to two freshwater algae, Chlamydomonas reinhardtii and Pseudokirchneriella subcapitata, grown under continuous culture conditions: Influence of thiosulphate

Hiriart-Baer, Véronique P.; Fortin, Claude; Lee, Dae-Young; Campbell, Peter G. C.

doi:10.1016/j.aquatox.2006.02.027

Cited by 80 publications

(45 citation statements)

References 21 publications

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“…[34] In this case, evidence that uptake was occurring over the sulphate transport system was provided by the observation uptake was significantly inhibited by the addition of sulphate. Nonetheless, the toxicity induced by the silver-thiosulphate complexes was not as important as that due to silver ions, [35] again demonstrating the importance of the intracellular fate of metal complexes once assimilated. Finally, although it is extremely difficult to distinguish transport of the complexes from that of a co-transport of inorganic phosphate and the metal ions, some bacteria (Escherichia coli [36] ; Arthrobacter sp.…”

Section: Introductionmentioning

confidence: 85%

When are metal complexes bioavailable?

Zhao¹,

Campbell²,

Wilkinson³

2016

Environ. Chem.

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Environmental context. The concentration of a free metal cation has proved to be a useful predictor of metal bioaccumulation and toxicity, as represented by the free ion activity and biotic ligand models. However, under certain circumstances, metal complexes have been shown to contribute to metal bioavailability. In the current mini-review, we summarise the studies where the classic models fail and organise them into categories based on the different uptake pathways and kinetic processes. Our goal is to define the limits within which currently used models such as the biotic ligand model (BLM) can be applied with confidence, and to identify how these models might be expanded.Abstract. Numerous data from studies over the past 30 years have shown that metal uptake and toxicity are often best predicted by the concentrations of free metal cations, which has led to the development of the largely successful free-ion activity model (FIAM) and biotic ligand model (BLM). Nonetheless, some exceptions to these classical models, showing enhanced metal bioavailability in the presence of metal complexes, have also been documented, although it is not yet fully understood to what extent these exceptions can or should be generalised. Only a few studies have specifically measured the bioaccumulation or toxicity of metal complexes while carefully measuring or controlling metal speciation. Fewer still have verified the fundamental assumptions of the classical models, especially when dealing with metal complexes. In the current paper, we have summarised the exceptions to classical models and categorised them into five groups based on the fundamental uptake pathways and kinetic processes. Our aim is to summarise the mechanisms involved in the interaction of metal complexes with organisms and to improve the predictive capability of the classic models when dealing with complexes.

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Section: Introductionmentioning

confidence: 85%

When are metal complexes bioavailable?

Zhao¹,

Campbell²,

Wilkinson³

2016

Environ. Chem.

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“…Speciation for the given metal affects toxicity, and it has also been shown that intracellular metal speciation may be important for bioavailability and toxicity [23].…”

Section: Glutathione Response To Cu and CDmentioning

confidence: 99%

“…Uptake of metals as inorganic complexes through sulfate transporters has also been observed, and this uptake mechanism may affect toxicity. Hiriart-Baer et al [23] reported that anionic silver thiosulphate complexes were bioavailable to green algae but were less toxic than silver taken up by cation transporters.…”

Section: Introductionmentioning

confidence: 98%

Differential effects of copper and cadmium exposure on toxicity endpoints and gene expression in Chlamydomonas reinhardtii

Stoiber

Shafer

Armstrong

2009

Enviro Toxic and Chemistry

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Abstract-The toxicity of cadmium to aquatic organisms is well known, but the mechanisms of toxicity are not as clearly understood. In the present study, Cd bioassay experiments incorporating both traditional endpoints and novel thiol-based endpoints were conducted with Chlamydomonas reinhardtii. The results were compared with results from previous bioassay experiments to probe the apparent contrasting biochemical mechanisms of toxicity of copper and cadmium as expressed in cellular glutathione and the glutathione cycle. Total glutathione and reduced to oxidized glutathione ratio (GSH/GSSG) measurements were remarkably different in Cd-compared with Cu-exposed cells. Whereas total glutathione in cells decreased with increasing Cu concentration, Cd caused dramatic increases. Total glutathione increased by 4.5-fold with 80 nM Cd treatment over concentrations in Cd-free controls. Glutathione reductase (GR) enzyme activity was positively correlated (r 2 Cu ¼ 0.96, r 2 Cd ¼ 0.85) with glutathione concentrations for both metals. Measurements of mRNA for GR were increased 2-fold in response to Cd exposure (80 nM) and correlated well with GR enzyme activity. Glutathione concentrations and GR enzyme activity are useful endpoints for both Cu and Cd toxicity in algae, even though the metals elicit opposing responses. We conclude that Cu decreases glutathione concentrations by inhibiting GR enzyme activity. In contrast, Cd stimulates GR enzyme activity and increases glutathione concentrations as cells respond to Cd-induced stress by producing increased antioxidant capacity. The present study demonstrates that determining the glutathione response in cells is important for understanding the metalspecific mechanisms of toxicity and that these associated novel endpoints may be useful metrics for accurately predicting toxicity.

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“…Furthermore, silver will form complexes with chloride (Fortin and Campbell 2000) or even more stable complexes with thiosulfate (Hiriart-Baer et al 2006). Aquatic silver toxicity has been found to depend on the free Ag + ion concentration as well as other dissolved chemical species of silver.…”

Section: Fate and Behaviour Of Silver In Freshwatermentioning

confidence: 99%

Potential risks and benefits of nanotechnology: perceptions of risk in sunscreens

Wright

2016

Medical Journal of Australia

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Toxicity of silver to two freshwater algae, Chlamydomonas reinhardtii and Pseudokirchneriella subcapitata, grown under continuous culture conditions: Influence of thiosulphate

Cited by 80 publications

References 21 publications

When are metal complexes bioavailable?

When are metal complexes bioavailable?

Differential effects of copper and cadmium exposure on toxicity endpoints and gene expression in Chlamydomonas reinhardtii

Potential risks and benefits of nanotechnology: perceptions of risk in sunscreens

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