Toxicological effects induced by the nanomaterials fullerene and nanosilver in the polychaeta Laeonereis acuta (Nereididae) and in the bacteria communities living at their surface.

TLDR: Analysis of antioxidant and oxidative damage responses of anterior, middle and posterior region of L. acuta and bacteria communities after nC60 or nAg exposure during 24 h showed a prevalence of Vibrio genera in the communities.

About: This article is published in Marine Environmental Research.The article was published on 2013-08-01 and is currently open access. It has received 29 citations till now. The article focuses on the topics: Nereididae.

Figures

Fig. 3. Total antioxidant capacity against peroxyl radicals (relative area) of the bacterial samples exposed to different fullerene (nC60) (a) and nanosilver (nAg) (b) concentrations. Asterisk (*) indicates significant differences (p < 0.05) between treatments connected by solid lines. Number of analyzed samples were 3 for each treatment being conducted three independent experiments (n ¼ 9).

Fig. 4. Total antioxidant capacity against peroxyl radicals (relative area) in the anterior (a), middle (b) and posterior (c) region of Laeonereis acuta exposed to different fullerene (nC60) concentrations. (d), (e) and (f) shows total antioxidant capacity against peroxyl radicals (relative area) in the anterior, middle and posterior region, respectively, of Laeonereis acuta exposed to different nanosilver (nAg) concentrations. Asterisk (*) indicates significant differences (p < 0.05) between treatments connected by solid lines. Number of analyzed samples were 5 for each treatment being conducted three independent experiments (n ¼ 15).

Fig. 5. Concentration of thiobarbituric acid reactive substances (TBARS; nmol/mg of proteins) in anterior (a), middle (b) and posterior (c) region exposed to different fullerene (nC60) concentrations. Asterisk (*) indicates significant differences (p < 0.05) between treatments connected by solid lines. Number of analyzed samples were 5 for each treatment being conducted three independent experiments (n ¼ 15).

Fig. 6. Activity of glutathione-S-transferase (GST) (nmol CDNB-GSh/min/mg prot) in anterior (a) middle (b) and posterior region (c) exposed to different fullerene (nC60) concentrations. Number of analyzed samples were 5 for each treatment, being conducted three independent experiments (n ¼ 15). Different letters indicate significant differences (p < 0.05) between means of different treatments. Number of analyzed samples were 5 for each treatment, being conducted three independent experiments (n ¼ 15).

Fig. 1. Transmission electron microscopy image of the aqueous fullerene (nC60) (a) and nanosilver (nAg) (b) suspensions employed in the bioassays.

Table 1 Molecular identification of bacteria living at the surface of the estuarine polychaete Laeonereis acuta.

Frequently asked questions

Q1. What contributions have the authors mentioned in the paper "Toxicological effects induced by the nanomaterials fullerene and nanosilver in the polychaeta laeonereis acuta (nereididae) and in the bacteria communities living at their surface" ?

The authors analyzed the antioxidant and oxidative damage responses of anterior, middle and posterior region of L. acuta and bacteria communities after nC60 or nAg exposure during 24 h. 

Q2. What is the widely accepted mechanism to explain nanosilver effects on biota?

Slow nanosilver dissolution to form silver ions is the most widely accepted mechanism described in the literature to explain nanosilver effects on biota. 

Q3. What is the role of nC60 in the detoxification of cells?

Enzymes of glutathione-S-transferase (GST) group play a key role in cellular detoxification, protecting cells against pollutants or toxicants by conjugating them to glutathione and other endogenous molecules. 

Q4. What is the genus of bacteria that is common in marine organisms?

The genus Vibrio sp. are Gram-negative bacteria, pathogenic to vertebrate and invertebrate animals (Kim and Bang, 2008), whereas the Shewanella genus comprises a group of Gram-negative bacteria that have been isolated from marine environments, sediments and marine organisms like abalone Haliotis discus hannai (Kim et al., 2007). 

Q5. Why is it possible to observe higher toxicity at lower test concentrations?

According to Tiede et al. (2009), it is possible to observe higher toxicity at lower test concentrations because the extent of aggregation at these concentrations can be likely reduced, leaving free particles in un-aggregated form. 

Q6. What was the main support for the study?

The logistic and material support from the Instituto Nacional de Ciência e Tecnologia de Nanomateriais de Carbono (CNPq) was fundamental for the execution of present study. 

Q7. What is the expected concentration of nAg in the aquatic environment?

The predicted concentration of nAg in the aquatic environment is estimated to be about 0.01 mg/L (Tiede et al., 2009), but given the increasing number of applications, the discharge of nAg will undoubtedly increase in the near future (Bilberg et al., 2011). 

Q8. What did Bradford et al. (2009) find?

The study of Bradford et al. (2009) observed that tanks containing sediment and estuarine water exposed to 1000 mg/L of silver nanoparticles presented high water silver concentration after dosing during 20 days. 

Q9. What is the effect of fullerene on the antioxidant capacity of L. acut?

In fact these authors observed that under this exposure condition, fullerene elicited an antioxidant response triggering higher total antioxidant competence against peroxyl radicals in exposed worms. 

Q10. What are the environmental conditions that affect the toxicity of nAg?

As mentioned previously, environmental conditions such as pH, ionic strength, presence of complexing agents, and natural organic matter affect the toxicity of nAg (Marambio-Jones and Hoek, 2010). 

Q11. What is the effect of nC60 on the antioxidant capacity of L. acut?

In this study the authors observed both conditions, since lipid peroxides content was reduced in the anterior region of worms exposed to the two highest concentrations (0.1 and 1.0 mg/L) of nC60, indicating an antioxidant behavior (Fig. 5a). 

Q12. What was the effect of nC60 on the worms?

Levels of lipid peroxidation (TBARS) were reduced in the anterior region of worms exposed to the two highest concentrations (0.1 and 1.0 mg/L) of nC60 (p < 0.05) (Fig. 5a). 

Q13. Why is nC60 used to perform the assays?

it can be considered that nC60 may have caused alterations in the antioxidant capacity in the anterior region L. acuta, through of ROS, due to OM presence in the estuarine water and employed to perform the assays.