Acute Exposure to Biogenic Nanosilver Produced from Fusarium oxysporum in a Neotropical Fish.

Biogenic nanosilver (bNAg) has emerged as a potentially less toxic alternative to synthetic nanosilver. However, no studies have evaluated its effects on a fish species from the Neotropical region. Thus, our aim was to evaluate the effects of a bNAg on the Neotropical fish Prochilodus lineatus. For this purpose, after 24 h of exposure to 100 µg L-1 of bNAg, blood samples were collected to evaluate hematological, genotoxic, and plasma parameters. Gills and liver were sampled to evaluate biomarkers of oxidative stress and brain samples were used to assess neurotoxicity. The fish presented hyperglycemia, an increased number of erythrocytes, a reduction in antioxidant enzyme activity in both tissues evaluated, and a decrease in lipid peroxidation in the gills. We concluded that P. lineatus is a sensitive species to this nanoparticle, since it presented alterations in several biomarkers after an acute exposure.

Cadmium effects on the freshwater teleost Prochilodus lineatus: Accumulation and biochemical, genotoxic, and behavioural biomarkers.

In order to evaluate the effects of Cd, juveniles of the Neotropical fish Prochilodus lineatus were exposed to 1 and 10 µg L-1 Cd, for 24 and 96 h. Fish exposed to Cd showed metal accumulation in the gills, kidney, and liver, an increase in DNA damage in erythrocytes, and an increase in lipid peroxidation (LPO) in the kidney. Cd exposure also caused a reduction in catalase activity, metallothionein induction, and LPO in the liver. Cd stimulated the swimming activity of exposed fish, resulting in longer swimming times and distances travelled, especially for the shortest exposure time. Changes in acetylcholinesterase activity (AChE) in the muscle and brain are probably related to these behavioural responses. These results show that Cd affects the functioning of several organs in P. lineatus, which is indicated by the genotoxic damage and changes in the AChE and swimming pattern of the exposed fish.

Can Lemna minor mitigate the effects of cadmium and nickel exposure in a Neotropical fish?

We aimed to evaluate if Lemna minor can mitigate the observed effects of cadmium (Cd) and nickel (Ni) exposure in Prochilodus lineatus. Fish were exposed for 96 h to 20 µg L-1 of Cd, 1.5 mg L-1 of Ni, or to a mixture of these two metals. In all tests, one group was exposed to the metals with duckweed on the water surface, and other group was exposed only to the metals, without plants. After each exposure, samples of P. lineatus tissues were collected to evaluate multiple biomarkers. Duckweed prevented bioaccumulation in some fish tissues and attenuated changes in acetylcholinesterase activity, increases in erythrocytic nuclear abnormality frequency, and hyperglycemia. However, the changes in plasma ion concentrations, reduction in activity of ion transport enzymes, and histological damage were not mitigated. Therefore, we concluded that L. minor partially attenuates the effects caused by Cd and Ni exposure.

Biochemical, physiological, and histological changes in the neotropical fish Prochilodus lineatus exposed to diesel oil.

Toxicity tests were conducted simulating a diesel oil spill in a tropical environment and juveniles of Prochilodus lineatus were exposed to the water-soluble fraction of diesel oil (WSD) for 6, 24, 96 h, and 15 days. The results showed the activation of biotransformation pathways for xenobiotics, through a time-dependent increase of liver GST activity. WSD caused a decrease in hematocrit and hemoglobin content, very likely due to hemolysis. Furthermore, an increase in glucose levels was observed after acute exposure to WSD. A possible lack of cortisol response could also be associated with WSD, since a reduction in plasma cortisol was seen in fish exposed to the petroleum product for 15 days. Moreover, the occurrence of lesions in the gills and even more severe lesions in the liver, should lead to functional damage to both organs, interfering thus directly with fundamental processes for the maintenance of homeostasis in this fish.