Sublethal Responses Research Articles

Deltamethrin-Induced Respiratory and Behavioral Effects and Adverse Outcome Pathways (AOP) in Short-Term Exposed Mozambique Tilapia, Oreochromis mossambicus.

Disrupted behavior and respiratory distress effects of 96-h acute deltamethrin exposures in adult Mozambique tilapia, Oreochromis mossambicus, were investigated using behavioral indices and opercular movement, respectively. Deltamethrin concentrations were found to be associated with toxicological (lethal and sublethal) responses. At 24, 48, 72, and 96 h, the LC50 values and 95% confidence limits were 12.290 (11.174-14.411 µg/L), 12.671 (11.334-15.649 µg/L), 10.172 (9.310-11.193 µg/L), and 8.639 (7.860-9.417 µg/L), respectively. The GUTS-model analysis showed that GUTS-SD (stochastic death) with a narrow tolerance distribution in deltamethrin exposed O. mossambicus populations was more sensitive than the GUTS-IT (individual tolerance) model. Prior to death, exposed fish demonstrated concentration-dependent mortality and disturbed behavioral responses, including uncoordinated swim motions, increased mucus secretion, unbalanced and unpredictable swimming patterns, and inactivity. The altered behavioral patterns and increased opercular movement with increased deltamethrin levels and exposure time are strongly suggestive of neurotoxicity and respiratory distress, respectively. Adverse Outcome Pathways (AOPs), describing biological mechanisms and plausible pathways, highlighted oxidative stress and cholinergic effects as intermediate steps linked to respiratory distress and behavioral toxicity.

Mechanism insights into bacterial sporulation at natural sphalerite interface with and without light irradiation: The suppressing role in bacterial sporulation by photocatalysis.

Unveiling the mechanisms of bacterial sporulation at natural mineral interfaces is crucial to fully understand the interactions of mineral with microorganism in aquatic environment. In this study, the bacterial sporulation mechanisms of Bacillus subtilis (B. subtilis) at natural sphalerite (NS) interface with and without light irradiation were systematically investigated for the first time. Under dark condition, NS was found to inactivate vegetative cells of B. subtilis and promote their sporulation simultaneously. The released Zn2+ from NS was mainly responsible for the bacterial inactivation and sporulation. With light irradiation, the photocatalytic effect from NS could increase the bacterial inactivation efficiency, while the bacterial sporulation efficiency was decreased from 8.1% to 4.5%. The photo-generated H2O2 and O2- played the major roles in enhancing bacterial inactivation and suppressing bacterial sporulation process. The intracellular synthesis of dipicolinic acid (DPA) as biomarker for sporulation was promoted by NS in dark, which was suppressed by the photocatalytic effect of NS with light irradiation. The transformation process from vegetative cells to spores was monitored by both 3D-fluerecence EEM and SEM observations. Compared with the NS alone system, the NS/light combined system induced higher level of intracellular ROSs, up-regulated antioxidant enzyme activity and decreased cell metabolism activity, which eventually led to enhanced inactivation of vegetative cells and suppressed bacterial sporulation. These results not only provide in-depth understanding about bacterial sporulation as a new mode of sub-lethal stress response at NS interface, but also shed lights on putting forward suitable strategies for controlling spore-producing bacteria by suppressing their sporulation during water disinfection.

Effects of aqueous extracts of wildfire ashes on tadpoles of Pelophylax perezi: Influence of plant coverage

Wildfires have been pointed out as an important source of diffuse contamination to aquatic ecosystems, namely through the input of toxic compounds such as polycyclic aromatic hydrocarbons and metals. However, amphibians' responses to this disturbance have been largely ignored. Hence, this study intended to assess how ashes from Pinus sp. and Eucalyptus sp. plantation forests affect tadpoles of Pelophylax perezi. Tadpoles were exposed 14 days to serial concentrations (26.9 %–100 %) of aqueous extracts of ashes (AEA, with 10 g L−1 of ashes) containing Eucalypt (ELS) and Pine (PLS) ashes. The following endpoints were measured: mortality, malformations, developmental stage, body length and weight. Effects at sub-individual level were also monitored for oxidative stress, neurotoxicity, and energetic metabolism. Chemical characterization of the AEA of ELS showed higher concentrations of As, Cd, Co, Cr, Pb and V, while PLS showed higher concentrations of Cu, Mn, Ni and Zn. Concerning the lethal effects of AEAs on tadpoles, both extracts were able to induce mortality at high concentrations (76.9 and/or 100 % of AEA), although a high variability in the response was found. A significant mortality in tadpoles exposed to ELS was observed at the concentration of 76.9 %. For organisms exposed to PLS, though a mortality above 20 % was registered at the two highest tested concentrations, it was not significantly different from the control. No significant sub-lethal effects were observed in the ELS treatments. Contrasting, exposure to PLS induced a decrease in body length, weight, glutathione-S-transferase activity and an increase in oxygen consumption. Overall, the distinct effects of ELS and PLS suggest an influence of vegetation cover in ash toxicity. In conclusion, exposure to both ash extracts negatively affected sublethal responses of tadpoles of P. perezi. Future research is needed to assess how these effects at individual level may translate into effects at population level.

The aquatic macrophyte Salvinia molesta mitigates herbicides (glyphosate and aminomethylphosphonic acid) effects to aquatic invertebrates.

We evaluated the individual and combined effects of different environmentally representative concentrations of glyphosate (0, 25, 50, 75, and 100µgl-1) and aminomethylphosphonic acid (AMPA; 0, 12.5, 25, 37.5, and 50µgl-1) on the physiology of Aedes aegypti larvae, as well as the capacity of the aquatic macrophyte Salvinia molesta to attenuate those compounds' toxicological effects. Larvae of Ae. aegypti (between the third and fourth larval stages) were exposed for 48h to glyphosate and/or AMPA in the presence or absence of S. molesta. Glyphosate and AMPA induced sublethal responses in Ae. aegypti larvae during acute exposures. Plants removed up to 49% of the glyphosate and 25% of AMPA from the water, resulting in the exposure of larvae to lower concentration of those compounds in relation to media without plants. As a result, lesser effects of glyphosate and/or AMPA were observed on larval acetylcholinesterase, P450 reductase, superoxide dismutase, mitochondrial electron transport chain enzymes, respiration rates, and lipid peroxidation. In addition to evidence of deleterious effects by media contamination with glyphosate and AMPA on aquatic invertebrates, our results attest to the ability of S. molesta plants to mitigate the toxicological impacts of those contaminants.

Ecological risk of imidacloprid on the Brazilian non-target freshwater organisms Chironomus sancticaroli and Poecilia reticulata.

Imidacloprid (IMI) is a neonicotinoid insecticide widely used in agriculture worldwide. This pesticide has been found in freshwater ecosystems, including Brazilian freshwaters. For this reason, studies are being conducted to detect the presence of IMI in freshwater and understand its effects on the aquatic biota. In the present study, the acute toxic effect of the imidacloprid commercial formulation (ICF) Galeão® on the Brazilian non-target aquatic organisms Chironomus sancticaroli and Poecilia reticulata was evaluated. Enzymatic activities (glutathione S-transferase (GST), catalase (CAT), and ascorbate peroxidase (APX)) were also determined. Moreover, we considered 11 studies that detected IMI concentrations up to 3.65µg.L-1 in 28 different Brazilian freshwaters to evaluate the acute ecological risk of IMI in these environments. From the ecotoxicological assays, we determined the LC50 values for C. sancticaroli (LC50-48h 1.52µg.L-1) and P. reticulata (LC50-96h 122.65mg.L-1). The high sensitivity of C. sancticaroli demonstrates that this species could be used as a bioindicator in studies investigating the contamination of freshwater by IMI. Enzymatic activity changes were observed in both organisms and offered sublethal responses to the effects of the pollution by IMI on aquatic biota. Our results suggest that the presence of IMI in Brazilian aquatic ecosystems can represent a potential ecological risk for the aquatic insect populations and, consequently, cause an imbalance in these ecosystems. The present study provides relevant and comparable toxicity information that may be useful to develop public policies to protect the Brazilian aquatic ecosystem from IMI contamination.

Cold storage effects on lethal and sublethal responses of Amphibalanus amphitrite Nauplii

Bioassays are extensively used in ecotoxicology and there is a constant need for even more sensitive, reliable and easy to rear and obtain model organisms. Larvae of the crustacean Amphibalanus amphitrite are a good ecotoxicological model, for their high sensitivity to a wide range of toxicants and emerging contaminants. A standardized protocol for this toxicity bioassay has been recently proposed. Nevertheless, a limit of this model organism is the lack of resting stages and the need to use larvae immediately after their release from adults, thus increasing laboratory efforts related to the maintenance of adults. The aim of this work is to verify if short-term cold storage of A. amphitrite larvae prior to use in ecotoxicological tests may affect the ecotoxicological responses of these organisms. Three end-points (mortality, immobilization and swimming speed alteration) were measured on nauplii after storing them at 4 ± 1 °C for different times (24, 72 and 120 h) before bioassay set-up. Bioassays were set up using: (i) clean filtered natural sea water (0.22 µm FNSW), (ii) a reference toxicant (Cadmium Nitrate) and (iii) an environmental matrix (sediment elutriate). Results show that mortality, differently from the other two endpoints, was not affected by cold-storage. Even after 5 days of larvae storage at 4 ± 1 °C before bioassay set up, mortality data were comparable to those obtained for non-cold-stored organisms. Moreover, larval sensitivity to the reference toxicant and sediment elutriate did not change. Regarding the other two end points, low cadmium concentrations significantly changed immobility and swimming activity in cold-stored nauplii compared to larvae used immediately after larval release. In conclusion, short-term cold storage of A. amphitrite nauplii before bioassay set up is an appropriate procedure in ecotoxicological testing if mortality is the endpoint to be considered for final evaluation.

Intraspecific Variation in the Sublethal Effects of Physically and Chemically Dispersed Crude Oil on Early Life Stages of Atlantic Cod (Gadus morhua).

The offshore oil industry in Atlantic Canada necessitates a greater understanding of the potential impacts of oil exposure and spill response measures on cold-water marine species. We used a standardized scoring index to characterize sublethal developmental impacts of physically and chemically dispersed crude oil in early life stages of Atlantic cod (Gadus morhua) and assessed intraspecific variation in the response among cod families. Cod (origin: Scotian Shelf, Canada) were laboratory-crossed to produce embryos from five specific families, which were subsequently exposed prehatch to gradient dilutions of a water-accommodated fraction (WAF) and a chemically enhanced WAF (CEWAF; prepared with Corexit 9500A) for 24 h. Postexposure, live embryos were transferred into filtered seawater and monitored to hatch; then, all live fish had sublethal endpoints assessed using the blue-sac disease (BSD) severity index. In both WAF and CEWAF groups, increasing exposure concentrations (measured as total petroleum hydrocarbons) resulted in an increased incidence of BSD symptoms (impaired swimming ability, increased degree of spinal curvature, yolk-sac edemas) in cod across all families. This positive concentration-dependent increase in BSD was similar between physically (WAF) versus chemically (CEWAF) dispersed oil exposures, indicating that dispersant addition does not exacerbate the effect of crude oil on BSD incidence in cod. Sensitivity varied between families, with some families having less BSD than others with increasing exposure concentrations. To our knowledge, our study is the first to demonstrate the occurrence in fishes of intraspecific variation among families in sublethal responses to oil and dispersant exposure. Our results suggest that sublethal effects of crude oil exposure will not be uniformly observed across cod populations and that sensitivity depends on genetic background. Environ Toxicol Chem 2022;41:1967-1976. © 2022 SETAC.

Phenotypic and Gene Expression Profiles of Embryo Development of the Ascidian Ciona robusta Exposed to Dispersants

Within EU approval policies, most dispersant ecotoxicity testing considers lethal concentrations for marine adult species, overlooking the embryotoxicological effects. Here we studied the ecotoxicity of two commercial dispersant formulations (dispersant A and B) on the embryogenesis of the ascidian Ciona robusta. Embryotoxicity and phenotypic alterations stated that dispersant B resulted more toxic than A (EC50 value of 44.30 and 160 μg mL−1, respectively) and induced severe larvae malformations at lower concentrations. Furthermore, the analysis of genes involved in different cellular response pathways indicated that those belonging to biotransformation were upregulated by dispersant A treatment, likely related to the presence of hydrocarbons. Instead, dispersant B induced cas8 gene downregulation, probably as a result of the prolonged exposure to mixture components. Our preliminary findings support the use of the C. robusta embryotoxicity test as a valuable tool for dispersant approval procedures, by providing sub-lethal responses on marine invertebrates closely related to vertebrates.

Is the ghost crab’s feeding behavior a good early indicator of human pressure in sandy beaches?

Phenotypic plasticity is a trait found among organisms that dwell in dynamic ecosystems such as sandy beaches. One of the main model of ecological studies in this ecosystem are ghost crabs (Crustacea: Ocypodidae), which present trophic plasticity and are considered ecological-disturbance indicator species. Their reactions to these impacts can manifest as sublethal responses, including behavioral aspects. We aimed to evaluate possible effects of urbanization on the feeding behavior of the ghost crab Ocypode quadrata (Fabricius, 1787). The study was conducted in a beach arc categorized into three urbanization levels located in the northern Rio de Janeiro state, Brazil. Each sector was sampled twice during high and low tourist seasons. The crabs’ diet was described by inspecting their digestive tracts with a stereomicroscope. Food preference (the choice of food items by each individual) and behavioral aspects (i.e., time of emergence from burrows, look-out time, number of choices, and handling time of the resource provided) were observed through in situ experiments, where food items were placed around burrows. The behavioral aspects were not affected by urbanization level. The diet mainly consisted of insects and macroalgae, though during experiments the species selected the most caloric items (fish and the bivalve Donax hanleyanus), regardless of the urbanization level. Local human disturbances seemed neither to change the availability of local resources nor to select individuals by feeding behavior. Therefore, there was no evidence that the feeding behavior of ghost crabs can be considered as a potential early indicator of human disturbance.

Transcriptional responses of Daphnia magna exposed to Akaki river water

Pollution of the aquatic environment is a global problem, with industrial waste, farming effluents, sewage, and wastewater as the main contributors. Many pollutants are biologically active at low concentrations, resulting in sublethal effects, which makes it a highly complex situation and difficult to assess. In many places, such as the Akaki river in Ethiopia, the pollution situation has resulted in streams with minimal presence of invertebrates or vertebrates. As it is difficult to perform a complete chemical analysis of the waters, the present study focused on using gene expression analysis as a biological end point to determine the effects of Akaki river contaminants. The present study was conducted using the small planktonic crustacean Daphnia magna with toxicogenomic molecular markers. Daphnia magna neonates were exposed to Akaki water samples collected from two different sites on the river and analyzed for mortality and expression of genes involved in different biological pathways. Despite the poor quality of Akaki river water, 48 h acute toxicity tests showed no mortality. Interestingly, analysis of sublethal toxicogenomic responses showed that exposure to Akaki water altered the expression of 25 out of 37 genes involved in metal regulation, immune response, oxidative stress, respiration, reproduction, and development. The toxicogenomic data gives insight into the mechanisms involved in causing potential adverse effects to aquatic biota harboring the Akaki river system.

Effects of Current and Future Summer Marine Heat Waves on Posidonia oceanica: Plant Origin Matters?

Marine heat waves (MHWs), prolonged discrete anomalously warm water events, have been increasing significantly in duration, intensity and frequency all over the world, and have been associated with a variety of impacts including alteration of ecosystem structure and function. This study assessed the effects of current and future MHWs on the Mediterranean seagrass Posidonia oceanica performance, also testing the importance of the thermal environment where the plant lives. The effects of current MHWs were studied through a mensurative experiment in a cold and in a warm site (West and North-West Sardinia, Italy, respectively). Future MHWs effects were tested through a manipulative experiment using P. oceanica shoots collected from the cold and warm sites and transplanted in a common garden in front of a power plant (North-West Sardinia): here plants were exposed to heat longer in duration and stronger in intensity than the natural MHWs of the last 20 years, resembling the future scenario. Morphological (total # of leaves, maximum leaf length, and percentage of total necrotic leaf length per shoot) and biochemical variables (leaf proteins, carbohydrates, and lipids) were considered. Plants had similar sublethal responses in both the experiments for most of the variables, revealing that current and future MHWs had similar effect types, but different in magnitude depending on the intensity of the waves: in general, the number of leaves, the maximum leaf length and lipid content decreased, while the leaf necrosis and carbohydrates increased. However, also the origin of the plants affected the results, corroborating the hypothesis that the thermal context the plants live affects their tolerance to the heat. Overall, this study provided evidence about the importance of biochemical variations, such as carbohydrate and lipid levels, as potentially good indicators of seagrass heat stress.

Disruption of mitochondrial quality control genes promotes caspase-resistant cell survival following apoptotic stimuli

In cells undergoing cell-intrinsic apoptosis, mitochondrial outer membrane permeabilization (MOMP) typically marks an irreversible step in the cell death process. However, in some cases, a subpopulation of treated cells can exhibit a sublethal response, termed “minority MOMP.” In this phenomenon, the affected cells survive, despite a low level of caspase activation and subsequent limited activation of the endonuclease caspase-activated DNase (DNA fragmentation factor subunit beta). Consequently, these cells can experience DNA damage, increasing the probability of oncogenesis. However, little is known about the minority MOMP response. To discover genes that affect the MOMP response in individual cells, we conducted an imaging-based phenotypic siRNA screen. We identified multiple candidate genes whose downregulation increased the heterogeneity of MOMP within single cells, among which were genes related to mitochondrial dynamics and mitophagy that participate in the mitochondrial quality control (MQC) system. Furthermore, to test the hypothesis that functional MQC is important for reducing the frequency of minority MOMP, we developed an assay to measure the clonogenic survival of caspase-engaged cells. We found that cells deficient in various MQC genes were indeed prone to aberrant post-MOMP survival. Our data highlight the important role of proteins involved in mitochondrial dynamics and mitophagy in preventing apoptotic dysregulation and oncogenesis.

Insights into the ecotoxicological perturbations induced by the biocide Abamectin in the white snail, Theba pisana

Abamectin (avermectin B1, ABM) has been widely used as a biocide in agriculture, veterinary and medicine around the world. Yet, there is still a lack of knowledge about the ecotoxicological effects of ABM. In this study, we investigated the acute toxicity and sub-lethal (20% and 60% LD50) biochemical responses of ABM on the non-target land snail, Theba pisana. Mortality of snails increased with the dose increase, resulting 48 h- LD50 value of 1.048 µg/snail. The biochemical results showed a decrease in glycogen content and lipids for two sub-lethal doses after all time intervals, whereas increased the level of total proteins after exposure to 60% LD50 ABM. Overall, the tested sub-lethal doses significantly decreased the total energy reserves. ABM-exposure to snails elevated γ-Glutamyl transferase and Lactate dehydrogenase activities at all-time intervals. A significant increase of Glutathione-S-transferase activity was also recorded in snails exposed to 20% and 60% LD50 after 7 days and all time intervals, respectively. However, ABM inhibited the activity of Aspartate aminotransferase and Alanine aminotransferase after 7 days of exposure. Our investigation provides new insights into the disturbances of energy reserves and enzyme activities in T. pisana that are sensitive and may be used as biomarkers for assessing ABM toxicity.

Microplastics In The Marine Environment, Presence In Water And Interaction With Marine Organisms.

This study is done in the framework of CLAIM project (Cleaning Litter by developing & Applying Innovative Methods in European seas). The objective is to advance the knowledge on the current status of marine plastic pollution in the Gulf of Gabes area of the Mediterranean Sea, by quantifying and qualifying the microplastics in water and biota samples. The results obtained show a high abundance of microplastics in all marine compartments studied with an average abundance of 1.16 items/m3 ± 0.83 SD in the water sample. This concentration is relatively high compared to those reported in other Mediterranean regions. Dominance in number of fragments over other shapes of microplastics was reported in all sites. Polyethylene was the main plastic polymer for water samples (73% of the items analyzed are Polyethylene). These data underscore that the Gulf of Gabes region is a hotspot for plastic pollution, and this calls urgently for precautionary measures. Concerning the ingestion of microplastics by marine organisms, one blue plastic particle of 0.13 mm was found in 20 tested fishes. In addition, ecotoxicological tests were run in order to verify whether 1-4 and 20-25 μm polyethylene beads are likely to trigger lethal and sub-lethal responses in marine planktonic crustaceans and the results show that microplastics were accumulated in crustaceans, and may affect mortality.

Sublethal responses of the indicator Unio species (mussel) to selected phthalate esters

Sublethal responses of the indicator Unio species (mussel) to selected phthalate esters

Prior exposure to weathered oil influences foraging of an ecologically important saltmarsh resident fish.

Estuarine ecosystem balance typically relies on strong food web interconnectedness dependent on a relatively low number of resident taxa, presenting a potential ecological vulnerability to extreme ecosystem disturbances. Following the Deepwater Horizon (DwH) oil spill disaster of the northern Gulf of Mexico (USA), numerous ecotoxicological studies showed severe species-level impacts of oil exposure on estuarine fish and invertebrates, yet post-spill surveys found little evidence for severe impacts to coastal populations, communities, or food webs. The acknowledgement that several confounding factors may have limited researchers’ abilities to detect negative ecosystem-level impacts following the DwH spill drives the need for direct testing of weathered oil exposure effects on estuarine residents with high trophic connectivity. Here, we describe an experiment that examined the influence of previous exposure to four weathered oil concentrations (control: 0.0 L oil m−2; low: 0.1 L oil m−2; moderate: 0.5–1 L oil m−2; high: 3.0 L oil m−2) on foraging rates of the ecologically important Gulf killifish (Fundulus grandis). Following exposure in oiled saltmarsh mesocosms, killifish were allowed to forage on grass shrimp (Palaeomonetes pugio) for up to 21 h. We found that previous exposure to the high oil treatment reduced killifish foraging rate by ~37% on average, compared with no oil control treatment. Previous exposure to the moderate oil treatment showed highly variable foraging rate responses, while low exposure treatment was similar to unexposed responses. Declining foraging rate responses to previous high weathered oil exposure suggests potential oil spill influence on energy transfer between saltmarsh and off-marsh systems. Additionally, foraging rate variability at the moderate level highlights the large degree of intraspecific variability for this sublethal response and indicates this concentration represents a potential threshold of oil exposure influence on killifish foraging. We also found that consumption of gravid vs non-gravid shrimp was not independent of prior oil exposure concentration, as high oil exposure treatment killifish consumed ~3× more gravid shrimp than expected. Our study findings highlight the sublethal effects of prior oil exposure on foraging abilities of ecologically valuable Gulf killifish at realistic oil exposure levels, suggesting that important trophic transfers of energy to off-marsh systems may have been impacted, at least in the short-term, by shoreline oiling at highly localized scales. This study provides support for further experimental testing of oil exposure effects on sublethal behavioral impacts of ecologically important estuarine species, due to the likelihood that some ecological ramifications of DwH on saltmarshes likely went undetected.

Toxicity of clothianidin to common Eastern North American fireflies.

BackgroundPrevious research suggests that fireflies (Coleoptera: Lampyridae) are susceptible to commonly used insecticides. In the United States, there has been a rapid and widespread adoption of neonicotinoid insecticides, predominantly used as seed coatings on large-acreage crops like corn, soy, and cotton. Neonicotinoid insecticides are persistent in soil yet mobile in water, so they have potential to contaminate firefly habitats both in and adjacent to application sites. As a result, fireflies may be at high risk of exposure to neonicotinoids, possibly jeopardizing this already at-risk group of charismatic insects.MethodsTo assess the sensitivity of fireflies to neonicotinoids, we exposed larvae of Photuris versicolor complex and Photinus pyralis to multiple levels of clothianidin-treated soil and monitored feeding behavior, protective soil chamber formation, intoxication, and mortality.ResultsPt. versicolor and Pn. pyralis larvae exhibited long-term intoxication and mortality at concentrations above 1,000 ng g−1 soil (1 ppm). Under sub-lethal clothianidin exposure, firefly larvae fed less and spent less time in protective soil chambers, two behavioral changes that could decrease larval survival in the wild.DiscussionBoth firefly species demonstrated sub-lethal responses in the lab to clothianidin exposure at field-realistic concentrations, although Pt. versicolor and Pn. pyralis appeared to tolerate higher clothianidin exposure relative to other soil invertebrates and beetle species. While these two firefly species, which are relatively widespread in North America, appear somewhat tolerant of neonicotinoid exposure in a laboratory setting, further work is needed to extend this conclusion to wild populations, especially in rare or declining taxa.

Combining short-term bioassays using fish and crustacean model organisms with ToxCast in vitro data and broad-spectrum chemical analysis for environmental risk assessment of the river water (Sava, Croatia)

This study focused on the short-term whole organism bioassays (WOBs) on fish (Danio rerio) and crustaceans (Gammarus fossarum and Daphnia magna) to assess the negative biological effects of water from the major European River Sava and the comparison of the obtained results with in vitro toxicity data (ToxCast database) and Risk Quotient (RQ) methodology. Pollution profiles of five sampling sites along the River Sava were assessed by simultaneous chemical analysis of 562 organic contaminants (OCs) of which 476 were detected. At each sampling site, pharmaceuticals/illicit drugs category was mostly represented by their cumulative concentration, followed by categories industrial chemicals, pesticides and hormones. An exposure-activity ratio (EAR) approach based on ToxCast data highlighted steroidal anti-inflammatory drugs, antibiotics, antiepileptics/neuroleptics, industrial chemicals and hormones as compounds with the highest biological potential. Summed EAR-based prediction of toxicity showed a good correlation with the estimated toxicity of assessed sampling sites using WOBs. WOBs did not exhibit increased mortality but caused various sub-lethal biological responses that were dependant relative to the sampling site pollution intensity as well as species sensitivity. Exposure of G. fossarum and D. magna to river water-induced lower feeding rates increased GST activity and TBARS levels. Zebrafish D. rerio embryo exhibited a significant decrease in heartbeat rate, failure in pigmentation formation, as well as inhibition of ABC transporters. Nuclear receptor activation was indicated as the biological target of greatest concern based on the EAR approach. A combined approach of short-term WOBs, with a special emphasis on sub-lethal endpoints, and chemical characterization of water samples compared against in vitro toxicity data from the ToxCast database and RQs can provide a comprehensive insight into the negative effect of pollutants on aquatic organisms.

Lethal and Sublethal Responses of Hydropsyche pellucidula (Insecta, Trichoptera) to Commercial Polypropylene Microplastics after Different Preconditioning Treatments.

Microplastics (MPs) pose biological and chemical hazards in aquatic and terrestrial food webs across the globe. Research on microplastic contamination has long focused on marine ecosystems, whereas the toxicological impact on freshwater organisms is still little explored. In this study, the lethal and sublethal response of the freshwater macroinvertebrate Hydropsyche pellucidula exposed to polypropylene MPs after different pre-conditioning treatments was assessed. Field samples were collected in a riverine system (Vipacco river; northeast Italy) to assess the characteristics of the MPs in the aquatic environment Both water and sediment were contaminated by MPs (3.73 ± 2.11 items m−3 per min and 3.33 ± 4.16 items dm−3, respectively). The chemical MPs composition included polystyrene, polyethylene terephthalate, polyurethane, polyamide, polypropylene, and polyethylene. Polypropylene (PP), although not the most abundant polymer recorded in the study area, was preferred over the other types according to its abundance in freshwater and H. pellucidula feeding behavior. A housing test was performed to recreate the natural conditions of larvae sampled for a reliable response to the ecotoxicological tests. The microplastics underwent either preconditioning with Vipacco River water (PP-river) and surfactant Triton X-100 (PP-sf) or no pre-treatment (PP). Submersion of microplastics in 10 µg L−1 of surfactant solution for 24 h was sufficient to induce consistent spectral changes and modify the chemical profile of the plastic surface. Mortality rate differed according to treatment: PP and PP-river > positive control > PP-sf > negative control. Integrated biomarker response (IBRv2) and analysis of oxidative stress biomarker levels showed a greater response of superoxide dismutase and lipid peroxidation (malondialdehyde) in larvae treated with PP conditioned in surfactant. Our findings enhance knowledge on the toxicity of PP and conditioning phases on H. pellucidula larvae.

Dietary nanoparticles compromise epithelial integrity and enhance translocation and antigenicity of milk proteins: An in vitro investigation

Nanoparticles (NPs) are increasingly being used in the food sector, yet little is known about the potential health risks associated with oral exposure to dietary NPs. In this study, the most widely used NPs in food industry including food grade silicon dioxide (SiO2), titanium dioxide (TiO2) and silver (Ag), along with their non-food grade and bulk counterparts, are characterized for physicochemical properties and molecular, cellular, and intracellular effects on human intestinal epithelial cells (Caco-2 and HIEC-6). Silver NPs are the most cytotoxic and induce significant cellular changes in oxidative stress, Ca2+ flux and mitochondria function, leading to cellular junction disruption at the lowest exposure concentration. At higher testing concentrations, NPs but not microparticles of SiO2 and TiO2 cause sublethal cellular responses and remodel tight junctions without impairing epithelial integrity. To relate the cellular results to key events in GI disorder progression, NPs are exposed to an in vitro co-culture model for cow's milk allergy comprised of Caco-2 and allergy sera-primed mast cells (LUVA). All particle treatments increase the allergen delivery across intestinal epithelium and subsequent allergy responses. Overall, the study has identified a particle-dependent alteration in intestinal epithelium and highlighted potential safety concerns of dietary NPs.