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Mechanisms of Toxicity of Ag Nanoparticles in Comparison to Bulk and Ionic Ag on Mussel Hemocytes and Gill Cells.

Katsumiti A, Gilliland D, Arostegui I, Cajaraville MP - PLoS ONE (2015)

Bottom Line: Maltose alone provoked minor effects on cell viability.Similar effects were observed after exposure to ionic and bulk Ag in the two cell types, although generally effects were more marked for the ionic form.In conclusion, results suggest that most observed responses were due at least in part to dissolved Ag.

View Article: PubMed Central - PubMed

Affiliation: CBET Research Group, Department of Zoology and Animal Cell Biology, Faculty of Science and Technology and Research Centre for Experimental Marine Biology and Biotechnology PIE, University of the Basque Country UPV/EHU, Plentzia, Spain.

ABSTRACT
Silver nanoparticles (Ag NPs) are increasingly used in many products and are expected to end up in the aquatic environment. Mussels have been proposed as marine model species to evaluate NP toxicity in vitro. The objective of this work was to assess the mechanisms of toxicity of Ag NPs on mussel hemocytes and gill cells, in comparison to ionic and bulk Ag. Firstly, cytotoxicity of commercial and maltose stabilized Ag NPs was screened in parallel with the ionic and bulk forms at a wide range of concentrations in isolated mussel cells using cell viability assays. Toxicity of maltose alone was also tested. LC50 values were calculated and the most toxic Ag NPs tested were selected for a second step where sublethal concentrations of each Ag form were tested using a wide array of mechanistic tests in both cell types. Maltose-stabilized Ag NPs showed size-dependent cytotoxicity, smaller (20 nm) NPs being more toxic than larger (40 and 100 nm) NPs. Maltose alone provoked minor effects on cell viability. Ionic Ag was the most cytotoxic Ag form tested whereas bulk Ag showed similar cytotoxicity to the commercial Ag NPs. Main mechanisms of action of Ag NPs involved oxidative stress and genotoxicity in the two cell types, activation of lysosomal AcP activity, disruption of actin cytoskeleton and stimulation of phagocytosis in hemocytes and increase of MXR transport activity and inhibition of Na-K-ATPase in gill cells. Similar effects were observed after exposure to ionic and bulk Ag in the two cell types, although generally effects were more marked for the ionic form. In conclusion, results suggest that most observed responses were due at least in part to dissolved Ag.

No MeSH data available.


Related in: MedlinePlus

DNA damage in mussel cells exposed to ionic Ag, bulk Ag and Ag NPs.Results of the Comet assay in mussel hemocytes and gill cells exposed to ionic Ag (A), bulk Ag (B) and Ag20-Mal NPs (C) for 24 h. Data are given as arbitrary values for tail DNA (means ± confidence intervals). Cells exposed to 50 μM H2O2 were used as positive control. Stars indicate significant differences (p<0.05) in treated cells with respect to controls according to the bootstrap analysis followed by Bonferroni’s correction. n = 50 cells analyzed per treatment.
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pone.0129039.g010: DNA damage in mussel cells exposed to ionic Ag, bulk Ag and Ag NPs.Results of the Comet assay in mussel hemocytes and gill cells exposed to ionic Ag (A), bulk Ag (B) and Ag20-Mal NPs (C) for 24 h. Data are given as arbitrary values for tail DNA (means ± confidence intervals). Cells exposed to 50 μM H2O2 were used as positive control. Stars indicate significant differences (p<0.05) in treated cells with respect to controls according to the bootstrap analysis followed by Bonferroni’s correction. n = 50 cells analyzed per treatment.

Mentions: DNA damage was found in hemocytes exposed to the three forms of Ag and in gill cells exposed to ionic Ag and Ag20-Mal NPs (Fig 10). Hydrogen peroxide (50 μM), used as positive control in the Comet assay, showed the highest levels of DNA damage in both cell types (Fig 10). Ionic Ag produced DNA damage starting at 0.06 mg Ag/L exposure in hemocytes (12% increase) and starting at a higher concentration (0.12 mg Ag/L) in gill cells (35% increase) (p<0.05) (Fig 10A). Bulk Ag was genotoxic only in hemocytes exposed to the maximum concentration tested (10 mg Ag/L) (16% increase) (p<0.05) (Fig 10B). Ag20-Mal NPs produced DNA damage at 1.25 and 2.5 mg Ag/L in hemocytes (22–37% increase) and at 2.5 mg Ag/L in gill cells (32% increase) (p<0.05) (Fig 10C).


Mechanisms of Toxicity of Ag Nanoparticles in Comparison to Bulk and Ionic Ag on Mussel Hemocytes and Gill Cells.

Katsumiti A, Gilliland D, Arostegui I, Cajaraville MP - PLoS ONE (2015)

DNA damage in mussel cells exposed to ionic Ag, bulk Ag and Ag NPs.Results of the Comet assay in mussel hemocytes and gill cells exposed to ionic Ag (A), bulk Ag (B) and Ag20-Mal NPs (C) for 24 h. Data are given as arbitrary values for tail DNA (means ± confidence intervals). Cells exposed to 50 μM H2O2 were used as positive control. Stars indicate significant differences (p<0.05) in treated cells with respect to controls according to the bootstrap analysis followed by Bonferroni’s correction. n = 50 cells analyzed per treatment.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4465040&req=5

pone.0129039.g010: DNA damage in mussel cells exposed to ionic Ag, bulk Ag and Ag NPs.Results of the Comet assay in mussel hemocytes and gill cells exposed to ionic Ag (A), bulk Ag (B) and Ag20-Mal NPs (C) for 24 h. Data are given as arbitrary values for tail DNA (means ± confidence intervals). Cells exposed to 50 μM H2O2 were used as positive control. Stars indicate significant differences (p<0.05) in treated cells with respect to controls according to the bootstrap analysis followed by Bonferroni’s correction. n = 50 cells analyzed per treatment.
Mentions: DNA damage was found in hemocytes exposed to the three forms of Ag and in gill cells exposed to ionic Ag and Ag20-Mal NPs (Fig 10). Hydrogen peroxide (50 μM), used as positive control in the Comet assay, showed the highest levels of DNA damage in both cell types (Fig 10). Ionic Ag produced DNA damage starting at 0.06 mg Ag/L exposure in hemocytes (12% increase) and starting at a higher concentration (0.12 mg Ag/L) in gill cells (35% increase) (p<0.05) (Fig 10A). Bulk Ag was genotoxic only in hemocytes exposed to the maximum concentration tested (10 mg Ag/L) (16% increase) (p<0.05) (Fig 10B). Ag20-Mal NPs produced DNA damage at 1.25 and 2.5 mg Ag/L in hemocytes (22–37% increase) and at 2.5 mg Ag/L in gill cells (32% increase) (p<0.05) (Fig 10C).

Bottom Line: Maltose alone provoked minor effects on cell viability.Similar effects were observed after exposure to ionic and bulk Ag in the two cell types, although generally effects were more marked for the ionic form.In conclusion, results suggest that most observed responses were due at least in part to dissolved Ag.

View Article: PubMed Central - PubMed

Affiliation: CBET Research Group, Department of Zoology and Animal Cell Biology, Faculty of Science and Technology and Research Centre for Experimental Marine Biology and Biotechnology PIE, University of the Basque Country UPV/EHU, Plentzia, Spain.

ABSTRACT
Silver nanoparticles (Ag NPs) are increasingly used in many products and are expected to end up in the aquatic environment. Mussels have been proposed as marine model species to evaluate NP toxicity in vitro. The objective of this work was to assess the mechanisms of toxicity of Ag NPs on mussel hemocytes and gill cells, in comparison to ionic and bulk Ag. Firstly, cytotoxicity of commercial and maltose stabilized Ag NPs was screened in parallel with the ionic and bulk forms at a wide range of concentrations in isolated mussel cells using cell viability assays. Toxicity of maltose alone was also tested. LC50 values were calculated and the most toxic Ag NPs tested were selected for a second step where sublethal concentrations of each Ag form were tested using a wide array of mechanistic tests in both cell types. Maltose-stabilized Ag NPs showed size-dependent cytotoxicity, smaller (20 nm) NPs being more toxic than larger (40 and 100 nm) NPs. Maltose alone provoked minor effects on cell viability. Ionic Ag was the most cytotoxic Ag form tested whereas bulk Ag showed similar cytotoxicity to the commercial Ag NPs. Main mechanisms of action of Ag NPs involved oxidative stress and genotoxicity in the two cell types, activation of lysosomal AcP activity, disruption of actin cytoskeleton and stimulation of phagocytosis in hemocytes and increase of MXR transport activity and inhibition of Na-K-ATPase in gill cells. Similar effects were observed after exposure to ionic and bulk Ag in the two cell types, although generally effects were more marked for the ionic form. In conclusion, results suggest that most observed responses were due at least in part to dissolved Ag.

No MeSH data available.


Related in: MedlinePlus