Exposure of adult zebrafish (Danio rerio) to SARS-CoV-2 at predicted environmentally relevant concentrations: Outspreading warns about ecotoxicological risks to freshwater fish.

While the multifaceted social, economic, and public health impacts associated with the COVID-19 pandemic are known, little is known about its effects on non-target aquatic ecosystems and organisms. Thus, we aimed to evaluate the potential ecotoxicity of SARS-CoV-2 lysate protein (SARS.CoV2/SP02.2020.HIAE.Br) in adult zebrafish (Danio rerio) at predicted environmentally relevant concentrations (0.742 and 2.226 pg/L), by 30 days. Although our data did not show locomotor alterations or anxiety-like or/and anxiolytic-like behavior, we noticed that exposure to SARS-CoV-2 negatively affected habituation memory and social aggregation of animals in response to a potential aquatic predator (Geophagus brasiliensis). An increased frequency of erythrocyte nuclear abnormalities was also observed in animals exposed to SARS-CoV-2. Furthermore, our data suggest that such changes were associated with a redox imbalance [↑ROS (reactive oxygen species), ↑H2O2 (hydrogen peroxide), ↓SOD (superoxide dismutase), and ↓CAT (catalase)], cholinesterasic effect [↑AChE (acetylcholinesterase) activity], as well as the induction of an inflammatory immune response [↑NO (nitric oxide), ↑IFN-γ (interferon-gamma), and ↓IL-10 (interleukin-10)]. For some biomarkers, we noticed that the response of the animals to the treatments was not concentration-dependent. However, principal component analysis (PCA) and the "Integrated Biomarker Response" index (IBRv2) indicated a more prominent ecotoxicity of SARS-CoV-2 at 2.226 pg/L. Therefore, our study advances knowledge about the ecotoxicological potential of SARS-CoV-2 and reinforces the presumption that the COVID-19 pandemic has negative implications beyond its economic, social, and public health impacts.

Short-term exposure of the mayfly larvae (Cloeon dipterum, Ephemeroptera: Baetidae) to SARS-CoV-2-derived peptides and other emerging pollutants: A new threat for the aquatic environments.

The input of SARS-CoV-2 or its fragments into freshwater ecosystems (via domestic or hospital sewage) has raised concerns about its possible impacts on aquatic organisms. Thus, using mayfly larvae [Cloeon dipterum (L.), Ephemeroptera: Baetidae] as a model system, we aimed to evaluate the possible effects of the combined short exposure of SARS-CoV-2-derived peptides (named PSPD-2001, PSPD-2002, and PSPD-2003 - at 266.2 ng/L) with multiple emerging pollutants at ambient concentrations. After six days of exposure, we observed higher mortality of larvae exposed to SARS-CoV-2-derived peptides (alone or in combination with the pollutant mix) and a lower-body condition index than those unexposed larvae. In the "PSPD" and "Mix+PSPD" groups, the activity of superoxide dismutase, catalase, DPPH radical scavenging activity, and the total thiol levels were also lower than in the "control" group. In addition, we evidenced the induction of nitrosative stress (inferred by increased nitrite production) and reduced acetylcholinesterase activity by SARS-CoV-2-derived peptides. On the other hand, malondialdehyde levels in larvae exposed to treatments were significantly lower than in unexposed larvae. The values of the integrated biomarker response index and the principal component analysis (PCA) results confirmed the similarity between the responses of animals exposed to SARS-CoV-2-derived peptides (alone and in combination with the pollutant mix). Although viral peptides did not intensify the effects of the pollutant mix, our study sheds light on the potential ecotoxicological risk associated with the spread of the new coronavirus in aquatic environments. Therefore, we recommend exploring this topic in other organisms and experimental contexts.

Can spike fragments of SARS-CoV-2 induce genomic instability and DNA damage in the guppy, Poecilia reticulate? An unexpected effect of the COVID-19 pandemic.

The identification of SARS-CoV-2 particles in wastewater and freshwater ecosystems has raised concerns about its possible impacts on non-target aquatic organisms. In this particular, our knowledge of such impacts is still limited, and little attention has been given to this issue. Hence, in our study, we aimed to evaluate the possible induction of mutagenic (via micronucleus test) and genotoxic (via single cell gel electrophoresis assay, comet assay) effects in Poecilia reticulata adults exposed to fragments of the Spike protein of the new coronavirus at the level of 40 µg/L, denominated PSPD-2002. As a result, after 10 days of exposure, we have found that animals exposed to the peptides demonstrated an increase in the frequency of erythrocytic nuclear alteration (ENA) and all parameters assessed in the comet assay (length tail, %DNA in tail and Olive tail moment), suggesting that PSPD-2002 peptides were able to cause genomic instability and erythrocyte DNA damage. Besides, these effects were significantly correlated with the increase in lipid peroxidation processes [inferred by the high levels of malondialdehyde (MDA)] reported in the brain and liver of P. reticulata and with the reduction of the superoxide dismutase (SOD) and catalase (CAT) activity. Thus, our study constitutes a new insight and promising investigation into the toxicity associated with the dispersal of SARS-CoV-2 peptide fragments in freshwater environments.