Figure - available from: Environmental Sciences Europe
This content is subject to copyright. Terms and conditions apply.
Source publication
The numbers of potential neurotoxicants in the environment are raising and pose a great risk for humans and the environment. Currently neurotoxicity assessment is mostly performed to predict and prevent harm to human populations. Despite all the efforts invested in the last years in developing novel in vitro or in silico test systems, in vivo tests...
Citations
... 29 Because the blood-brain barrier has not formed during this period, contaminants into the body can impair the development, structural integrity, and functional capabilities of neural cells. 30 The susceptibility of the neural system in the early developmental stage to environmental change has been well-documented. Alterations in locomotor behavior often function as a crucial marker of neurotoxicity given that locomotor activity exhibits greater susceptibility to the ecotoxicological impacts of pollutants in comparison to mortality rates. ...
The global accumulation and adverse effects of nanoplastics (NPs) are a growing concern for the environment and human health. In recent years, more and more studies have begun to focus on the toxicity of plastic particles for early animal development. Different particle sizes of plastic particles have different toxicities to biological development. Nevertheless, the potential toxicological effects of 20 nm NPs, especially on neurodevelopment, have not been well investigated. In this paper, we used fluorescence microscopy to determine neurotoxicity in zebrafish at different concentrations of NPs. Moreover, the behavioral analysis demonstrated that NPs induced abnormal behavior of zebrafish. The results revealed developmental defects in zebrafish embryos after exposure to different concentrations (0, 0.3, 3, and 9 mg/L) of NPs. The morphological deformities, including abnormal body length and the rates of heart, survival, and hatching, were induced after NP exposure in zebrafish embryos. In addition, the development of primary motor neurons was observed the inhibitory effects of NPs on the length, occurrence, and development of primary motor neurons in Tg(hb9:GFP). Quantitative polymerase chain reaction analysis suggested that exposure to NPs significantly affects the expression of the genes involved in the occurrence and differentiation of primary motor neurons in zebrafish. Furthermore, the indicators associated with oxidative stress and apoptosis were found to be modified in zebrafish embryos at 24 and 48 h following exposure to NPs. Our findings demonstrated that NPs could cause toxicity in primary motor neurons by activating the oxidative stress response and inducing apoptosis, consequently impairing motor performance.
... Considering the increasing number of environmental contaminants with neurotoxic potential (Busch et al. 2016), there is an urgent need for novel and sensitive endpoints to screen chemicals for potential neurotoxic effects (Morrissey et al. 2015; Legradi et al. 2018). Currently, risk assessments largely focus on mortality, growth, and reproduction (Schuijt et al. 2021). ...
The aim of this study is twofold: i) to determine innovative yet sensitive endpoints for sulfoxaflor and ii) to develop best practices for innovative teaching in ecotoxicology. To this end, a group of 52 MSc students participated in an environmental hackathon, during which they did creative toxicity testing on 5 freshwater invertebrate species: Daphnia magna, Chironomus riparius, Asellus aquaticus, Lymnaea stagnalis, and Anisus vortex. Involving the students in an active learning environment stimulated increased creativity and productivity. In total, 28 endpoints were investigated, including standard endpoints (e.g., mortality) as well as biomechanistic and energy-related endpoints. Despite high variances in the results, likely linked to the limited lab experience of the students and interpersonal differences, a promising set of endpoints was selected for further investigation. A more targeted follow-up experiment focused on the most promising organism and set of endpoints: biomechanistic endpoints of C. riparius larvae. Larvae were exposed to a range of sulfoxaflor concentrations (0.90–67.2 μg/L) for 21 days. Video tracking showed that undulation and swimming were significantly reduced at 11.1 μg sulfoxaflor/L after 9 days of exposure, and an EC50 = 10.6 μg/L for mean velocities of the larvae in the water phase was found. Biomechanistic endpoints proved much more sensitive than mortality, for which an LC50 value of 116 μg/L was found on Day 9. Our results show that performing a hackathon with students has excellent potential to find sensitive endpoints that can subsequently be verified using more targeted and professional follow-up experiments. Furthermore, utilising hackathon events in teaching can increase students’ enthusiasm about ecotoxicology, driving better learning experiences.
... Measurement of various respiration parameters at least in adult fish lifestages during acute toxicity tests as early signs of death (i.e., moribundity) might help to reduce suffering of animals and provide much more information about the specific mode of action than mere lethality. Replacing adult vertebrates in neurotoxicity testing with in vitro and in silico alternatives remain challenging due to the complex interplay of neuronal cell interactions in whole organisms, although the fish embryo toxicity test already provides the opportunity to integrate additional (e.g., behavior-based) endpoints (Legradi et al., 2018;Zindler et al., 2019aZindler et al., , 2019bZindler et al., , 2020. ...
... The exposure to insecticides causes as accumulation of neurotransmitters in neuromuscular synapses resulting in cholinergic toxicity (fikes, 1990(fikes, : Lotti, 2010)Neuronal degeneration (Thiripurasundari et al., 2014) as well as changing behavior as Tremor, convulsions, and paralysis of the limbs (Kushwaha et al., 2020;Mangas et al., 2017). The researchers found that insecticides interfere with physiological chemical processes and activities leading to abnormal neurobehavioral changes (Uggini et al., 2012;Legradi et al., 2018). ...
The aim of the study is to revealed on congenital malformations and histological changes of garati (lambda-cyhalothrin) insecticide on embryonic development chicken broiler ross 308. In the study, we used 250 fresh fertilize eggs for chicken broiler Ross 308 , and were divided to five groups included, control groups (negative and positive treated with distilled water) and the other four groups were treated with concentrations 360, 540, 900, 1800 ppm of insecticide lambda-cyhalothrin. The eggs were injected in to yolk sac with a single dose at 100 µL/egg after two days of incubation on 37 ± 0.5°C and humidity present 70-75%. The results showed after 10 and 21 days, that causes insecticide garati(lambda-cyhalothrin) congenital abnormalities as Micropthalima with swollen of the brain and deformation the beak. Furthermore, ectopic viscera, edema, and delayed retraction of the yolk sac with deformations in upper and lower extremities. Also, after 22 days of incubated , the results of the study revealed on behavioral changes like loss of ability to stand or walk with arching of fingers. Moreover, paralysis in limbs with general impairment of chicks body as well as coma. Microscopically, the cross section of the liver observed histological changes such as sinusoids expansion, central vein fibrosis, diffuse inflammatory cells, and necrotizing hepatocytes comparative with the control group. We conclude from the study, that exposure to the insecticide garati (lambda-cyhalothrin) causes congenital malformation and histological changes which may be reflected on the other vertebrates.
... Behaviour changes in treated Tubifex tubifex are typically recognised as an early symptom of an avoidance response caused by toxicant exposure, narcotic effects, or neurotoxic reactions. A behavioural biomarker is a type of early warning signal used in ecotoxicological risk assessment studies [51,52]. Worms exposed to cadmium frequently exhibited clumping, mucus formation and wrinkling effects. ...
Current environmental issues include heavy metal contamination. Cadmium pollution in aquatic environments harms aquatic creatures and can pass to people through food chains. Cadmium poisoning damages bones, kidneys and causes cancer. Tubifex tubifex is a well-known water pollution indicator because of its good adaptation power in environmental pollution. Tubifex sp. is chosen as the test animal in this study since it is an indicator species and also a model non-target organism in ecotoxicology. The aim of this present work is to assess the toxicity of cadmium nitrate on Tubifex tubifex as a biomarker. Acute toxicity of cadmium nitrate was analysed by measuring the 96 h LC 50 value. Physical observations revealed that cadmium induced autotomy of the caudal region of the worm and induced more mucus secretion. Behavioural alterations like changes in mucous secretion, clumping tendency and wrinkling effect were observed in cadmium-treated worms. Antioxidant enzymes level (MDA, CAT and SOD) increased significantly on cadmium nitrate exposure. In general, biomarker data show that cadmium exposure has stress-related consequences at the biochemical and physiological levels, reducing the overall health and survival of such animals. Highlights. The toxicity of the heavy metal cadmium in acute and sub-acute levels was investigated in Tubifex tubifex.. The goal of this study was to look at the effects of cadmium on oxidative stress and behavioural biomarkers in T. tubifex. Sublethal cadmium exposure can impact the physiological functioning of annelids in the wild. ARTICLE HISTORY
... It has been recently estimated that up to 30% of all commercial organic chemicals detected as micropollutants can target the central and peripheral nervous system (Legradi et al. 2018). These pollutants, here defined as neuroactive, are known to negatively affect aquatic organisms by causing developmental neurotoxicity, disturbances in electric signal transduction, inhibition of chemical signal transduction, and behavioral impairment at environmental relevant concentrations (Casida 2009;Casida and Durkin 2015;Legradi et al. 2018;Leuthold et al. 2018). ...
... It has been recently estimated that up to 30% of all commercial organic chemicals detected as micropollutants can target the central and peripheral nervous system (Legradi et al. 2018). These pollutants, here defined as neuroactive, are known to negatively affect aquatic organisms by causing developmental neurotoxicity, disturbances in electric signal transduction, inhibition of chemical signal transduction, and behavioral impairment at environmental relevant concentrations (Casida 2009;Casida and Durkin 2015;Legradi et al. 2018;Leuthold et al. 2018). In particular, acetylcholinesterase (AChE) inhibitors represent a broad group of neuroactive chemicals which can enter the environment through several anthropogenic sources such as agriculture, private gardening, veterinary, and medical practices. ...
Acetylcholinesterase (AChE) inhibitors are an important class of neuroactive chemicals that are often detected in aquatic and terrestrial environments. The correct functionality of the AChE enzyme is linked to many important physiological processes such as locomotion and respiration. Consequently, it is necessary to develop new analytical strategies to identify harmful AChE inhibitors in the environment. It has been shown that mixture effects and oxidative stress may jeopardize the application of in vivo assays for the identification of AChE inhibitors in the environment. To confirm that in vivo AChE assays can be successfully applied when dealing with complex mixtures, an extract from river water impacted by non-treated wastewater was bio-tested using the acute toxicity fish embryo test (FET) and AChE inhibition assay with zebrafish. The zebrafish FET showed high sensitivity for the extract (LC10 = relative extraction factor 2.8) and we observed a significant inhibition of the AChE (40%, p < 0.01) after 4-day exposure. Furthermore, the extract was chromatographically fractionated into a total of 26 fractions to dilute the mixture effect and separate compounds according to their physico-chemical properties. As expected, non-specific acute effects (i.e., mortality) disappeared or evenly spread among the fractions, while AChE inhibition was still detected in five fractions. Chemical analysis did not detect any known AChE inhibitors in these active fractions. These results confirm that the AChE assay with Danio rerio can be applied for the detection of neuroactive effects induced in complex environmental samples, but also, they highlight the need to increase analytical and identification techniques for the detection of neurotoxic substances.
... A behavioral change can essentially influence individual fitness, with consequences for population dynamics, species interactions, and ecosystem functions (Saaristo et al., 2018;Candolin and Wong, 2019), and thus has great ecological relevance that explains the growing interest in behavioral ecotoxicology (Ford et al., 2021;Bertram et al., 2022). As highlighted by Legradi et al. (2018), behavioral toxicity tests in small organisms are of special interest for aquatic econeurotoxicological screenings. Some behavioral endpoints have been suggested to investigate rapid acute neurotoxic responses or effects of longer exposures with consequences that may have a larger impact, such as neurodevelopmental effects (Legradi et al., 2018). ...
... As highlighted by Legradi et al. (2018), behavioral toxicity tests in small organisms are of special interest for aquatic econeurotoxicological screenings. Some behavioral endpoints have been suggested to investigate rapid acute neurotoxic responses or effects of longer exposures with consequences that may have a larger impact, such as neurodevelopmental effects (Legradi et al., 2018). ...
... The AChE assessment allowed us to distinguish between a neurotoxic effect and a stress reaction caused by the test substances. The measurement of AChE activity is a common biomarker in ecotoxicology due to its potential to determine the effect of organophosphorus (irreversible) and carbamate (reversible) pesticides (Legradi et al., 2018). The assay followed the method of Xuereb et al. (2009a) based on the original description of Ellman et al. (1961). ...
Sublethal effects are becoming more relevant in ecotoxicological test methods due to their higher sensitivity compared to lethal endpoints and their preventive nature. Such a promising sublethal endpoint is the movement behavior of invertebrates which is associated with the direct maintenance of various ecosystem processes, hence being of special interest for ecotoxicology. Disturbed movement behavior is often related to neurotoxicity and can affect drift, mate-finding, predator avoidance, and therefore population dynamics. We show the practical implementation of the ToxmateLab, a new device that allows monitoring the movement behavior of up to 48 organisms simultaneously, for behavioral ecotoxicology. We quantified behavioral reactions of Gammarus pulex (Amphipoda, Crustacea) after exposure to two pesticides (dichlorvos and methiocarb) and two pharmaceuticals (diazepam and ibuprofen) at sublethal, environmentally relevant concentrations. We simulated a short-term pulse contamination event that lasted 90 min. Within this short test period, we successfully identified behavioral patterns that were most pronounced upon exposure to the two pesticides: Methiocarb initially triggered hyperactivity, after which baseline behavior was restored. On the other hand, dichlorvos induced hypoactivity starting at a moderate concentration of 5 μg/L - a pattern we also found at the highest concentration of ibuprofen (10 μg/L). An additional acetylcholine esterase inhibition assay revealed no significant impact of the enzyme activity that would explain the altered movement behavior. This suggests that in environmentally realistic scenarios chemicals can induce stress - apart from mode-of-action - that affects non-target organisms' behavior. Overall, our study proves the practical applicability of empirical behavioral ecotoxicological approaches and thus represents a next step towards routine practical use.
... Behaviour is a sensitive ecotoxicological endpoint, providing quick responses to contaminant exposure at sublethal toxicity doses (Legradi et al., 2018;Robinson et al., 2009;Van der Geest et al., 1999), with behavioural ecotoxicology long being identified as a means for rapid early warning signs in marine and freshwater pollution (Hellou et al., 2011). Avoidance behaviour has been well studied for diverse taxa in response to contamination, such as for macroinvertebrates (Beketov et al., 2008;Gauthier et al., 2016;Nørum et al., 2010), pollutant tracking with bivalves (Castro et al., 2018), soil toxicity assessments with earthworms (Amorim et al., 2005;Hund-Rinke et al., 2001) or chronic exposure impacts to heavy metal pollution in fish (Faucher et al., 2008;Svecevičius et al., 1999). ...
Micropollutants are regularly detected at the outlets of wastewater treatment plants (WWTPs). Across urban and industrial WWTPs, monitoring directives only require assessment for a handful of chemicals via sampling methods that fail to capture the temporal variability in micropollutant discharge. In this study, we develop a biotest for real-time on-line monitoring of micropollutant discharge dynamics in WWTPs effluents. The selected biomonitoring device ToxMate uses videotracking of invertebrate movement, which was used to deduce avoidance behaviour of the amphipod Gammarus fossarum. Organism conditioning was set up to induce a state of minimal locomotor activity in basal conditions to maximise avoidance signal sensitivity to micropollutant spikes. We showed that with a standardised protocol, it was possible to minimise both overall movement and sensitivity to physio-chemical variations typical to WWTP effluents, as well as capture the spikes of two micropollutants upon exposure (copper and methomyl). Spikes in avoidance behaviour were consistently seen for the two chemicals, as well as a strong correlation between avoidance intensity and spiked concentration. A two-year effluent monitoring case study also illustrates how this biomonitoring method is suitable for real-time on-site monitoring, and shows a promising non-targeted approach for characterising complex micropollutant discharge variability at WWTP effluents, which today remains poorly understood.
... ◀ lipid metabolism, neurotoxicity, and other physiological changes that alter fish behavior is imperative (Chen et al., 2020;Legradi et al., 2018). ...
Fibrous microplastics are abundant in water, and the additives on fibers could also be transported jointly, which is a combined pollution scenario prevalent in the environment. Organisms ingest microplastics directly from the environment or indirectly through trophic transfer. However, there is a dearth of available information on the uptake and effects of fibers and their additives. This study investigated the uptake and depuration of polyester microplastic fibers (MFs, 3600 items/L) by adult female zebrafish via waterborne and foodborne exposure routes and the effects on the fish behavior. Moreover, we used brominated flame-retardant tris(2,3-dibromopropyl) isocyanurate (TBC, 5 μg/L) as a representative plastic additive compound and explored MFs' effects on the accumulation of TBC in zebrafish. Results substantiated that the highest MF concentrations in zebrafish from waterborne exposure (12.00 ± 4.59 items/tissue) were approximately three times higher than foodborne exposure, suggesting waterborne exposure as the primary ingestion route. In addition, environmentally relevant MF concentrations did not affect TBC bioaccumulation via aqueous exposure. However, MFs could decrease TBC accumulation via foodborne exposure by ingesting contaminated D. magna, which was probably because MF co-exposure decreased the TBC burden in daphnids. MF exposure also considerably increased behavioral hyperactivity in zebrafish. Moved speed, travelled distance, and active swimming duration all increased when exposed to MFs-containing groups. This phenomenon remained apparent in the foodborne exposure experiment with a low MF concentration (0.67-6.33 items/tissue) in zebrafish. This study offers a deeper understanding of MF uptake and excretion in zebrafish and the accumulation of the co-existing pollutant. We also confirmed that waterborne and foodborne exposure may lead to abnormal fish behavior even at low in vivo MF burdens.
... Behavior is seen as a highly organized, neural network-driven process that assures the fitness of organisms. As a result, behavioral alterations are frequently regarded as sensitive measures in ecotoxicological investigations for identifying neurological dysfunction caused by pollutant exposure (Legradi et al., 2018;Ford et al., 2021). The motor function of zebrafish embryos was analyzed through STC and TER (Drapeau et al., 2002). ...
Perfluorooctanesulfonic acid (PFOS) is a prevalent, persistent organic pollutant in environmental matrices, yet its precise mechanism of neurotoxicity remains unclear. This study investigated the developmental and neurobehavioral effects of PFOS exposure (0, 100, 500, and 1000 μg/L) on zebrafish. The findings indicated that PFOS exposure caused various developmental abnormalities, including increased mortality, delayed hatching, shortened body length, bent spine, and edema in the pericardial and yolk sac regions. Subsequently, larvae exhibited a significant decrease in spontaneous movement frequency, altered touch-evoked response, and locomotor behavior. In fact, aberrant cellular responses in the brain and cardiac regions were observed. Microglial activation is a critical component of the inflammatory immune responses related to neurotoxicity. Likewise, our findings indicate that PFOS-induced microglial activation might be responsible for neuronal inflammation and apoptosis. Furthermore, AChE activity and dopamine content at the neurotransmitter level were also disrupted after PFOS exposure. The gene expression of dopamine signaling pathways and neuroinflammation were also altered. Collectively, our findings highlight that PFOS exposure can induce dopaminergic neurotoxicity and neuroinflammation through microglial activation, thus ultimately affecting behavior. Taken together, this study will provide mechanistic effects underlying the pathophysiology of neurological disorders.
