Biogenic metallic nanoparticles (Ag, TiO2, Fe) as potential fungicides for agriculture: are they safe for the freshwater mussel Anodontites trapesialis?

Silver (Ag), titanium dioxide (TiO2), and iron (Fe) nanoparticles (NPs) synthesized using the fungus Trichoderma harzianum are effective against the agriculture pathogen Sclerotinia sclerotiorum. However, their effects should be evaluated in aquatic organisms, as agriculture practices can contaminate the aquatic environment. Thus, this work evaluated sublethal effects of acute exposure (24 h) to AgNP, TiO2NP and FeNP, synthesized with T. harzianum, on the Neotropical freshwater bivalve Anodontites trapesialis, considering the hypothesis that suspension-feeding bivalves are susceptible to NPs toxicity. Individuals of A. trapesialis were divided into four groups (n = 8/group): a control group, kept in water only; a group exposed to AgNP; a group exposed to TiO2NP; and a group exposed to FeNP. The bioaccumulation of Ag, Ti, and Fe was evaluated in the gills, hemolymph, mantle, digestive gland, and muscle (foot). Lipoperoxidation, activities of the glutathione S-transferase, catalase, and superoxide dismutase, and glycogen concentration were quantified in the gills, mantle, and digestive gland. Ions (Na+, K+, Cl-, Ca2+, and Mg+2) and glucose concentrations were quantified in the hemolymph. Na+/K+-ATPase, H+-ATPase, Ca2+-ATPase, and carbonic anhydrase activities were assessed in the gills and mantle. Acetylcholinesterase activity was determined in the foot and adductor muscle. The mussels exposed to AgNP accumulated Ag in the gills, hemolymph, and foot, and showed a decrease in hemolymph concentrations of Na+ and Cl-, which was associated with the action of Ag ion (Ag+). The exposures to TiO2NP and FeNP led to the accumulation of Ti and Fe in the hemolymph, respectively, but did not promote additional effects. Accordingly, A. trapesialis showed bioaccumulation potential and susceptibility to AgNP, but was not susceptible to TiO2NP and FeNP. Thus, the preferential agricultural use of TiO2NP and FeNP over AgNP is highlighted.

Sublethal effects of waterborne copper and copper nanoparticles on the freshwater Neotropical teleost Prochilodus lineatus: A comparative approach.

Copper nanoparticles can contaminate the aquatic environment, but their effects on fish and how they may differ from copper salts is not understood. Thus, in this work we compare the sublethal effects of copper nanoparticles (nCu) and copper chloride (Cu) on the freshwater teleost Prochilodus lineatus, known for its sensitivity to copper. Juveniles (n = 8/group) were exposed to 20 µg L-1 of copper as CuCl2 (Cu), 40 µg L-1 of copper nanoparticles (nCu), or only water (control), for 96 h. These concentrations were chosen to achieve similar dissolved copper concentration in both treatments (Cu: 10.29 ± 0.94 µg L-1; nCu: 12.16 ± 1.77 µg L-1). After the exposure, the following biological parameters were evaluated: copper accumulation in the gills, liver, gastrointestinal tract, kidney, and muscle; hematocrit (Ht) and hemoglobin content (Hb); branchial activity of Na+-K+-ATPase (NaKATP), H+-ATPase (HATP), Ca2+-ATPase (CaATP), and carbonic anhydrase (CA); glutathione content (GSH) and lipid peroxidation (LPO) in the liver; acetylcholinesterase activity (AChE) in the brain and muscle; and histopathology of the gills and liver. The gills of Cu-exposed fish were adversely affected, with increased copper content, inhibition of H+-ATPase and Ca2+-ATPase, and histological damage, including proliferation of mitochondria rich cells and/or mucous cells. In addition, LPO levels increased in the liver of Cu-exposed fish, indicating the occurrence of oxidative stress. Exposure to nCu promoted a decrease in Ht and Hb, indicating anemia, and an increase in branchial Na+-K+-ATPase and H+-ATPase activities, which can be an adaptive response to metabolic acidosis. Within the chosen biomarkers and the conditions tested, copper nanoparticles were less toxic than copper. However, the effects promoted by the nanoparticles were different from those promoted by copper. These results emphasize the need for a better understanding of copper nanoparticles toxicity in order to establish safe concentrations and avoid environment impacts.

An integrated approach in subtropical agro-ecosystems: Active biomonitoring, environmental contaminants, bioaccumulation, and multiple biomarkers in fish.

Aquatic contamination in agricultural areas is a global problem, characterized by a complex mixture of organic and inorganic pollutants whose effects on biota are unpredictable and poorly investigated. In this context, in the present study, the Neotropical fish Prochilodus lineatus was confined in situ for 120 days in two sites with different levels of anthropic impact: 1) a fish hatchery station, within the State University of Londrina (reference site - REF) and 2) an agro-ecosystem area in one of the most productive regions of southern Brazil (experimental site - EXP). We evaluated multiple biomarkers at different levels of biological organization, such as biotransformation and antioxidant enzymes, oxidative damages, DNA damages and liver histopathology. We also evaluated the occurrence of 22 organochlorine pesticides (OCPs) and 6 trace metals in water and sediment; and 33 current-use pesticides (CUPs) in the water; besides the presence of OCPs in the liver and metals in different tissues of the confined fish. The chemical analysis confirmed that the two environments presented different levels of contamination. We verified a distribution gradient of data in the principal component analysis (PCA), separating the REF fish to one side and the fish at the agricultural area (EXP) to the other side. In general, the biomarker responses were more altered in fish from the EXP than fish from the hatchery station; and this fish presented a greater accumulation of endosulfan (an increase of 18× compared to basal value) and showed oxidative, genetic, and histological damage. Through the Biomarkers Response Index (BRI), we found that the EXP fish demonstrated a decrease in health status compared with the REF fish during the confinement time, due to their exposure to a higher concentration of contaminants. In conclusion, the use of multiple biomarkers at different response levels is an important tool for environmental monitoring.