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Effect of compounds on catecholaminergic neurons in the zebrafish brain at 96 hpf. A: Diagrammatic representation of the dis- tribution of catecholaminergic neurons based on differential staining with various markers (from Holzschuh et al., 2001). B: Traced from a dorsal view photo of a TH-stained control embryo showing the 4 clusters of positive cells, divided into pairs of anterior (A) and posterior (P) groups. Comparison of the 2 diagrams suggests that A clusters correspond to several clusters of adrenergic/noradrenergic neurons and 2 large clusters of all 3 types of neurons, and P clusters correspond primarily to dopaminergic neurons. C: Catecholaminergic neurons in the brain at 96 hpf visualized by a -TH staining. Staining in control (0.1% DMSO) zebrafish is in 4 bilaterally symmetric clusters of neurons: 2 anterior (boxes) and 2 posterior groups (ovals). Cells in the anterior groups are missing and reduced in the posterior group of zebrafish exposed to 2,4-D (arrows); cells in both A and P groups are missing in nonylphenol-exposed zebrafish. AP, area post- rema; CE, corpus cerebellum; H, hypothalamus; LC, locus coeruleus; MO, medulla oblongata; OB, olfactory bulb; PA, pallium; PO, preoptic area; PR, pretectal area; PT, posterior tuberculum; SP, subpallium; TC, tectum; 1, anterior commissures; 2, 2nd ventricle; 3, optic chiasma.
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To establish zebrafish as a developmental toxicity model, we used 7 well-characterized compounds to examine several parameters of neurotoxicity during development.
Embryos were exposed by semistatic immersion from 6 hrs postfertilization (hpf). Teratogenicity was assessed using a modified method previously developed by Phylonix. Dying cells in the...
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... (Table 3). Zebrafish exposed to malathion had slightly thin capa, whereas the capa in zebrafish exposed to TCDD were thin and truncated. Nonylphenol did not appear to affect the axon tracts in the caudal embryo. We counted the number of a -TH–positive cells in 4 bilaterally symmetric compartments of the brain at 96 hpf (Fig. 7). The number of cells in the anterior (A) or posterior (P) compartments of 10 zebrafish was averaged for control or exposed zebrafish (Table 7). To compare the effect of different compounds, SIs (see Materials and We quantified the fluorescent signal from a -AT– Methods) were calculated. stained capa in the ventral aspect of 6 segments in the All 7 compounds significantly decreased the number of caudal region of the embryo (Figs. 5 and 6; Table 6). anterior cells. DDT, dieldrin, and nonylphenol also signif- Compounds significantly affecting fluorescent signal icantly decreased the number of posterior cells. Of the 7 were 2,4-D, DDT, and TCDD. 2,4-D and TCDD caused a compounds tested, nonylphenol and dieldrin had the significant loss of signal, whereas DDT increased signal. greatest effect on both anterior and posterior ...
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... counted the number of a-TH-positive cells in 4 bilaterally symmetric compartments of the brain at 96 hpf (Fig. 7). The number of cells in the anterior (A) or posterior (P) compartments of 10 zebrafish was averaged for control or exposed zebrafish (Table 7). To compare the effect of different compounds, SIs (see Materials and Methods) were ...
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Citations
... Existen otros estudios donde se demuestra que el índice teratogénico del DDT es de 3.5, siendo >1, lo que lo verifica como teratógeno (Ton et al., 2006). ...
The present research work was based on the evaluation of a method for the identification and quantification of chlorinated molecules belonging to a group of globally prohibited pesticides. Through the exhaustive literature review, a comparison of the analytical conditions was established for the implementation of a preparatory process for conditioning the matrix and for the instrumental determination of the analytes under study. The analysis conditions were studied experimentally to verify their efficiency by evaluating the recovery of the analytes in fresh and canned fish. For the extraction and purification of the extracts, the dispersive solid phase extraction technique (QuEChERS) was applied, and the analysis of the chlorinated compounds was carried out by coupling gas chromatography with detection by mass spectrometry (GC-MS) obtaining satisfactory results with a recovery of 60 - 140% for alpha lindane, delta lindane, aldrin, dieldrin, endosulfan I, endosulfan II, DDT, DDD, DDE and methoxychlor. The analyzed samples corresponded to Albacore fish (Thunnus albacares), Catfish (Bagre spp.), Tilapia (Oreochromis spp.) and Weevil (Istiompax indica), showing results below the limit of quantification <10 µg/Kg with the applied method. The results denote the analytical capacity of the methodology implemented with high sensitivity and demonstrate the suitability of the marine products sold in local markets.
... zebrafish and neural crest cells during development, playing a critical role in neurocranial cartilage and bone development. Developmental issues in the jaw are associated with bone formation or neural crest migration issues (Kimmel et al., 1998;TeSlaa et al., 2013;Ton et al., 2006). For all atrazine treatment groups' offspring, we saw a substantial reduction in PQ length. ...
... Also, measurements of the saccular otoliths' surface area and distance from one another in the progeny of the 30 ppb treatment group indicated that ossification had decreased. Our findings are comparable to the craniofacial hypoplasia reported in developing chicks (Joshi et al., 2013) as well as two other zebrafish studies finding a decreased ossification in exposed zebrafish 8 days post fertilization (Walker et al., 2018) and an undeveloped jaw at 96 hpf (Ton et al., 2006). The decrease in size of various cartilaginous structures contradicts another study where researchers found an increasing size of cartilaginous structures at 120 hpf (Walker et al., 2018). ...
... The jaw is derived from 7 pharyngeal arches by 5 days post fertilization (120 hpf) in the larval zebrafish and neural crest cells during development play a critical role in neurocranial cartilage and bone development. Malformations in the jaw are associated with bone formation or neural crest migrations issues (Kimmel et al. 1998;TeSlaa et al. 2013;Ton et al. 2006). Here, we observed a significant decrease in PQ length for progeny of all ATZ treatment groups and in CH-Meckel's length, jaw distance, and a more posteriorly positioned jaw as measured from the notochord in offspring of the 30 ppb ATZ treatment group. ...
... These morphological observations are comparable to the craniofacial hypoplasia reported in developing chicks exposed to N-nitrosoatrazine (Joshi et al. 2013). In addition, the current study agrees with two other zebrafish studies reporting decreased ossification of vertebrae in developmentally exposed zebrafish at 8 days post fertilization (Walker et al. 2018) and a visible phenotype of an underdeveloped jaw at 96 hpf (Ton et al. 2006). Alternatively, the decrease in size of various cartilaginous structures in the 30 ppb ATZ F1 treatment group at 120 hpf contradicts another study in zebrafish in which the authors found a trend of increasing size of cartilaginous structures at 120 hpf (Walker et al. 2018). ...
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... NP has ability to structurally resemble the endogenous hormone oestrogen and, in some situations, prevent its effects since it can cross the blood-brain barrier (Doerge et al., 2002;Litwa et al., 2014). NP and other EDCs affect the adrenergic neurons (Ton et al., 2006), neuronal nicotinic acetylcholine receptors (Nakazawa and Ohno, 2001) and also expression of iNOS and COX-2 (Zhang et al., 2008). NP has been also reported to alter the behaviour of zebrafish due to inhibition of the binding of androgens to their receptors (Mukherjee et al., 2022). ...
... Similar to this, zebrafish exposed to 17α-ethinylestradiol showed much higher latency to the light side (Volkova et al., 2015). Neurobehaviour alterations following exposure of nonylphenol in the present study might be due to its effect on adrenergic neurons (Ton et al., 2006), nicotinic receptors (Nakazawa and Ohno, 2001) and/or inhibition of binding of androgens to their receptors (Mukherjee et al., 2022). ...
Nonylphenol and its derivatives use as plasticizer or additives in manufacturing industries. Effluents originated from industrial areas are being added to soil, ground water, river and marine water intentionally or unintentionally. Complex mixture of these contaminants enter the food chain and produce sub-lethal deleterious effects mainly on nervous and reproductive systems of aquatic animals and human beings. The information pertaining to oxidative stress-mediated alterations in brain of zebrafish would be helpful to understand the toxicity potential of such compounds in aquatic animals. The aim of the present study was to evaluate the behavioural changes, status of oxidative stress markers; sod, cat, and NF-E2-related factor 2 (nrf2) mRNA gene expression profile; and histopathological changes in the brain of adult zebrafish exposed to 4-nonylphenol (4NP) at concentration of 100 and 200 μg/L of water for 21 days. Zebrafish were divided into four groups viz; control (C1), vehicle (C2, ethanol 10 μg/L of water), treatment 1 (T1, 4-NP, 100 μg/L) and treatment 2 (T2, 4-NP, 200 μg/L). Both exposure levels of 4-NP adversely affected the exploratory behaviour of zebrafish and produced anxiety-like symptom. Concentration-dependent reduction in activity of superoxide dismutase and catalase; and glutathione level, with increased level of malondialdehyde recorded in the brain of exposed zebrafish. Gene expression analysis showed down regulation of sod, cat, nrf2 genes in brain of zebrafish from toxicity groups indicating 4-NP induced oxidative stress in brain. However, noticeable histological alterations were not observed in 4-NP exposed brain of zebrafish.
... Several teratogenic influences have been shown in fish farming with OCPs exposure [260,270]. Ton et al. (2006) introduced a teratogenicity indicator as the dose ratio leading to 50% death (LC50) over the dose leading to 50% developmental abnormalities (EC50), i.e., the ratio of LC50/EC50. A scoring indicator >1 as teratogenic was evaluated. ...
... A scoring indicator >1 as teratogenic was evaluated. There was a relative teratogenic indicator of 3.5 for DDT at 96 host fertilization in the mentioned research, while the dieldrin value was 0.1 [271]. These values were compared with TCDD with high teratogenic potential with a rate of 15.3. ...
... A potential for deformity and malformations have been reported in response to the toxaphene toxins [272]. Increased dieldrin concentration, skeletal deformity, and cardiac hemorrhaging have been observed [268,271]. Toxaphene is a complicated mix of substances formed by the reaction of chlorine gas with camphene. Exposure to 15-20 mg of toxaphene per liter can cause deformity, including lack of pigmentation, the toxicity of spinal deformity, and yolk sack edema. ...
Endocrine-disrupting chemicals (EDCs) are a growing public health concern worldwide. Consumption of foodstuffs is currently thought to be one of the principal exposure routes to EDCs. However, alternative ways of human exposure are through inhalation of chemicals and dermal contact. These compounds in food products such as canned food, bottled water, dairy products, fish, meat, egg, and vegetables are a ubiquitous concern to the general population. Therefore, understanding EDCs' properties, such as origin, exposure, toxicological impact, and legal aspects are vital to control their release to the environment and food. The present paper provides an overview of the EDCs and their possible disrupting impact on the endocrine system and other organs.
... Zebrafish (Danio rerio) is a small freshwater teleost, carrying features, such as the genome, brain patterning, and the structure and function of neural and physiological systems, similar to other vertebrate species (Lockwood et al., 2004;Lieschke and Currie, 2007;Kily et al., 2008;Strähle et al., 2012). For example, studies with known mammalian neurotoxic and cardiotoxic agents have shown that these substances caused similar effects in zebrafish (Ton et al., 2006;Kari et al., 2007). Therefore, zebrafish have been widely . ...
Introduction:
Zebrafish is a suitable animal model for molecular genetic tests and drug discovery due to its characteristics including optical transparency, genetic manipulability, genetic similarity to humans, and cost-effectiveness. Mobility of the zebrafish reflects pathological conditions leading to brain disorders, disrupted motor functions, and sensitivity to environmental challenges. However, it remains technologically challenging to quantitively assess zebrafish's mobility in a flowing environment and simultaneously monitor cellular behavior in vivo.
Methods:
We herein developed a facile fluidic device using mechanical vibration to controllably generate various flow patterns in a droplet housing single zebrafish, which mimics its dynamically flowing habitats.
Results:
We observe that in the four recirculating flow patterns, there are two equilibrium stagnation positions for zebrafish constrained in the droplet, i.e., the "source" with the outward flow and the "sink" with the inward flow. Wild-type zebrafish, whose mobility remains intact, tend to swim against the flow and fight to stay at the source point. A slight deviation from streamline leads to an increased torque pushing the zebrafish further away, whereas zebrafish with motor neuron dysfunction caused by lipin-1 deficiency are forced to stay in the "sink," where both their head and tail align with the flow direction. Deviation angle from the source point can, therefore, be used to quantify the mobility of zebrafish under flowing environmental conditions. Moreover, in a droplet of comparable size, single zebrafish can be effectively restrained for high-resolution imaging.
Conclusion:
Using the proposed methodology, zebrafish mobility reflecting pathological symptoms can be quantitively investigated and directly linked to cellular behavior in vivo.
... Zebrafish serves as an appropriate model to predict teratogenesis and neurotoxicity in mammalian system. Atrazine, and TCDD are specifically recognised as teratogenic compounds in fishes whereas 2,4-dichlorophenoxyacetic acid (2,4-D), dieldrin, non-phenol, dieldrin and nonylphenol are neurotoxic causing catecholaminergic neuron toxicity in fish model [73]. Motor neuron functions like feeding, swimming, escaping from predators are affected by 2,4,-D sublethal exposure [74].It also causes apoptosis of brain cells, disrupted growth of motor neurons and decrease in motility and it is teratogenic to fishes [73]. ...
... Atrazine, and TCDD are specifically recognised as teratogenic compounds in fishes whereas 2,4-dichlorophenoxyacetic acid (2,4-D), dieldrin, non-phenol, dieldrin and nonylphenol are neurotoxic causing catecholaminergic neuron toxicity in fish model [73]. Motor neuron functions like feeding, swimming, escaping from predators are affected by 2,4,-D sublethal exposure [74].It also causes apoptosis of brain cells, disrupted growth of motor neurons and decrease in motility and it is teratogenic to fishes [73]. Atrazine affects production of dopamine, functionality of motor neurons, causes brain cell death and developmental toxicity [75]. ...
... DDT increases motility, causes apoptosis of brain cells, loss in catecholaminergic neurons and is highly teratogenic in both medium and high exposure. Dieldrin causes tremors and loss of dopaminergic neurons and is little teratogenic in fishes [73] .Malathion causes significant toxicity at early developmental stages and apoptosis of brain cells (Lien et al., 1997;Cook et al., 2005) .TCDD exposure causes pericardial oedema, retarded growth, decelerated circulation, vascular endothelial cell toxicity, brain cell necrosis and apoptosis, shrinkage of brain, decreased heart rate and motility and is highly teratogenic [78,79]. ...
In the past three decades biological and chemical pollutants have become a serious environmental issue posing major threat to the society, industries and public sectors. Toxic contaminants are produced in most household, agricultural and industrial activities. In the past few years different advanced electrochemical oxidation technologies and low-carbon technologies are being used widely for preventing environmental pollution and remediation of the micropollutants particularly in waterbodies. In these technologies powerful oxidizing agents like hydroxyl radicals are formed electrochemically which degrade organic micropollutants till their mineralization. Fish serves as an effective bioindicator of aquatic health due to their higher trophic position in aquatic food chain and high sensitivity to pollutants. As fishes are consumed by humans globally as a major source of protein, it is also used to indicate the impact of aquatic pollution on human health. In this review we discuss the impact of micropollutants on the fish physiology and the advanced wastewater management techniques used for rapid removal of these pollutants from aquatic ecosystem. Here we discuss both advantages and disadvantages of different commonly used wastewater management techniques which would be beneficial to determine which technology would best suit one’s specific requirements without causing much harm to the environment, a step towards green and sustainable future.
... Supplementary Materials: The following supporting information can be downloaded at: https: //www.mdpi.com/article/10.3390/ijms24043942/s1. References [24,25,88,89,94,95,122,123] ...
Non-alcoholic fatty liver disease (NAFLD), which starts with liver steatosis, is a growing worldwide epidemic responsible for chronic liver diseases. Among its risk factors, exposure to environmental contaminants, such as endocrine disrupting compounds (EDC), has been recently emphasized. Given this important public health concern, regulation agencies need novel simple and fast biological tests to evaluate chemical risks. In this context, we developed a new in vivo bioassay called StAZ (Steatogenic Assay on Zebrafish) using an alternative model to animal experimentation, the zebrafish larva, to screen EDCs for their steatogenic properties. Taking advantage of the transparency of zebrafish larvae, we established a method based on fluorescent staining with Nile red to estimate liver lipid content. Following testing of known steatogenic molecules, 10 EDCs suspected to induce metabolic disorders were screened and DDE, the main metabolite of the insecticide DDT, was identified as a potent inducer of steatosis. To confirm this and optimize the assay, we used it in a transgenic zebrafish line expressing a blue fluorescent liver protein reporter. To obtain insight into DDE’s effect, the expression of several genes related to steatosis was analyzed; an up-regulation of scd1 expression, probably relying on PXR activation, was found, partly responsible for both membrane remodeling and steatosis.
... The lasting impact of aberrant connectivity on brain function underscores the importance of studying how neural network formation is affected by contaminant exposures. Previous research identified AHR agonist-induced changes in the PNS of Atlantic seabream as well as structural differences and functional changes in larval zebrafish (Ton et al., 2006;Iida et al., 2013;Knecht et al., 2017;Holloway et al., 2021). Ton et al. (2006) found that TCDD exposure qualitatively reduced axon tracts in the developing zebrafish brain. ...
... Previous research identified AHR agonist-induced changes in the PNS of Atlantic seabream as well as structural differences and functional changes in larval zebrafish (Ton et al., 2006;Iida et al., 2013;Knecht et al., 2017;Holloway et al., 2021). Ton et al. (2006) found that TCDD exposure qualitatively reduced axon tracts in the developing zebrafish brain. Our findings significantly build on these initial reports and use highresolution confocal z-series in multiple orientations to identify Loss of ahr2 disrupts neural network formation without affecting brain size. ...
2,3,7,8-tetrachlorodibenzo-[p]-dioxin (TCDD) is a persistent global pollutant that exhibits a high affinity for the aryl hydrocarbon receptor (AHR), a ligand activated transcription factor. Epidemiological studies have associated AHR agonist exposure with multiple human neuropathologies. Consistent with the human data, research studies using laboratory models have linked pollutant-induced AHR activation to disruptions in learning and memory as well as motor impairments. Our understanding of endogenous AHR functions in brain development is limited and, correspondingly, scientists are still determining which cell types and brain regions are sensitive to AHR modulation. To identify novel phenotypes resulting from pollutant-induced AHR activation and ahr2 loss of function, we utilized the optically transparent zebrafish model. Early embryonic TCDD exposure impaired embryonic brain morphogenesis, resulted in ventriculomegaly, and disrupted neural connectivity in the optic tectum, habenula, cerebellum, and olfactory bulb. Altered neural network formation was accompanied by reduced expression of synaptic vesicle 2. Loss of ahr2 function also impaired nascent network development, but did not affect gross brain or ventricular morphology. To determine whether neural AHR activation was sufficient to disrupt connectivity, we used the Gal4/UAS system to express a constitutively active AHR specifically in differentiated neurons and observed disruptions only in the cerebellum; thus, suggesting that the phenotypes resulting from global AHR activation likely involve multiple cell types. Consistent with this hypothesis, we found that TCDD exposure reduced the number of oligodendrocyte precursor cells and their derivatives. Together, our findings indicate that proper modulation of AHR signaling is necessary for the growth and maturation of the embryonic zebrafish brain.
... Moreover, teratogenic types of effects recorded in zebrafish could frequently be correlated with corresponding observations in mammals, which indicates the utility and efficiency of the zebrafish embryo model for the detection of at least strong mammalian teratogenic compounds and toxicants (Ball et al. 2014;Brannen et al. 2010;Iida et al. 2019;Kim et al. 2011). Thus, over the last two decades, the zebrafish embryo has become a well-studied tool for the investigation of general vertebrate development and diseases, as well as one of the most promising models not only in ecotoxicity testing, but also in mammalian toxicology and in specific as a tool in assessing compounds for toxicity and safety liabilities in early drug development (Ali et al. 2011;Bambino and Chu 2017;Brannen et al. 2010;Braunbeck 2009;de Esch et al. 2012;Driessen et al. 2013;Fernandes et al. 2017;Guo et al. 2015;Hill 2012;Kari et al. 2007;Nishimura et al. 2015;Scholz 2013;Sipes et al. 2011;Sukardi et al. 2011;Tao and Peng 2009;Ton et al. 2006;Weigt et al. 2011). ...
Valproic acid is a frequently used antiepileptic drug and known pediatric hepatotoxic agent. In search of pharmaceuticals with increased effectiveness and reduced toxicity, analogue chemicals came into focus. So far, toxicity and teratogenicity data of drugs and metabolites have usually been collected from mammalian model systems such as mice and rats. However, in an attempt to reduce mammalian testing while maintaining the reliability of toxicity testing of new industrial chemicals and drugs, alternative test methods are being developed. To this end, the potential of the zebrafish ( Danio rerio ) embryo to discriminate between valproic acid and 14 analogues was investigated by exposing zebrafish embryos for 120 h post fertilization in the extended version of the fish embryo acute toxicity test (FET; OECD TG 236), and analyzing liver histology to evaluate the correlation of liver effects and the molecular structure of each compound. Although histological evaluation of zebrafish liver did not identify steatosis as the prominent adverse effect typical in human and mice, the structure–activity relationship (SAR) derived was comparable not only to human HepG2 cells, but also to available in vivo mouse and rat data. Thus, there is evidence that zebrafish embryos might serve as a tool to bridge the gap between subcellular, cell-based systems and vertebrate models.
