Academic literature on the topic 'Toxicity, behaviour, zebrafish'

The zebrafish (Danio rerio) has recently become a common model in the fields of genetics, environmental science, toxicology, and especially drug screening. Zebrafish has emerged as a biomedically relevant model forin vivohigh content drug screening and the simultaneous determination of multiple efficacy parameters, including behaviour, selectivity, and toxicity in the content of the whole organism. A zebrafish behavioural assay has been demonstrated as a novel, rapid, and high-throughput approach to the discovery of neuroactive, psychoactive, and memory-modulating compounds. Recent studies found a functional similarity of drug metabolism systems in zebrafish and mammals, providing a clue with why some compounds are active in zebrafishin vivobut notin vitro, as well as providing grounds for the rationales supporting the use of a zebrafish screen to identify prodrugs. Here, we discuss the advantages of the zebrafish model for evaluating drug metabolism and the mode of pharmacological action with the emerging omics approaches. Why this model is suitable for identifying lead compounds from natural products for therapy of disorders with multifactorial etiopathogenesis and imbalance of angiogenesis, such as Parkinson's disease, epilepsy, cardiotoxicity, cerebral hemorrhage, dyslipidemia, and hyperlipidemia, is addressed.

The influence of water chemistry on characterised polyvinyl pyrrolidone- (PVP-) coated silver nanoparticles (81 nm) was investigated. NaCl solution series of 100–800 mg L−1lead to initial and temporal increase in nanoparticles size, but agglomeration was limited. pH variation (5–8) had only minor influence on the hydrodynamic particle size. Acute toxicity of nanosivler to zebrafish (Danio rerio) was investigated in a 48-hour static renewal study and compared with the toxicity of silver ions (AgNO3). The nanosilver and silver ion 48-hour median lethal concentration (LC50) values were 84 μg L−1and 25 μg L−1, respectively. To investigate exposure-related stress, the fish behaviour was observed visually after 0, 3, 6, 12, 24, 27, 30, and 48 hours of both nanosilver and ionic silver treatments. These observations revealed increased rate of operculum movement and surface respiration after nanosilver exposure, suggesting respiratory toxicity. The present study demonstrates that silver nanoparticles are lethal to zebrafish.

Organophosphate (OP) insecticides are used to eliminate agricultural threats posed by insects, through inhibition of the neurotransmitter acetylcholinesterase (AChE). These potent neurotoxins are extremely efficacious in insect elimination, and as such, are the preferred agricultural insecticides worldwide. Despite their efficacy, however, estimates indicate that only 0.1% of organophosphates reach their desired target. Moreover, multiple studies have shown that OP exposure in both humans and animals can lead to aberrations in embryonic development, defects in childhood neurocognition, and substantial contribution to neurodegenerative diseases such as Alzheimer’s and Motor Neurone Disease. Here, we review the current state of knowledge pertaining to organophosphate exposure on both embryonic development and/or subsequent neurological consequences on behaviour, paying particular attention to data gleaned using an excellent animal model, the zebrafish (Danio rerio).

Bisphenol A (BPA), a well-known xenoestrogen, is commonly utilised in the production of polycarbonate plastics. Based on the existing evidence, BPA is known to induce neurotoxicity and behavioural issues. Flavonoids such as silibinin and naringenin have been shown to have biological activity against a variety of illnesses. The current research evaluates the neuropharmacological effects of silibinin and naringenin in a zebrafish model against neurotoxicity and oxidative stress caused by Bisphenol A. In this study, a novel tank diving test (NTDT) and light–dark preference test (LDPT) were used in neurobehavioural investigations. The experimental protocol was planned to last 21 days. The neuroprotective effects of silibinin (10 μM) and naringenin (10 μM) in zebrafish (Danio rerio) induced by BPA (17.52 μM) were investigated. In the brine shrimp lethality assay, the 50% fatal concentrations (LC50) were 34.10 μg/mL (silibinin) and 91.33 μg/mL (naringenin) compared to the standard potassium dichromate (13.15 μg/mL). The acute toxicity investigation found no mortality or visible abnormalities in the silibinin- and naringenin-treated groups (LC50 > 100 mg/L). The altered scototaxis behaviour in LDPT caused by BPA was reversed by co-supplementation with silibinin and naringenin, as shown by decreases in the number of transitions to the light zone and the duration spent in the light zone. Our findings point to BPA’s neurotoxic potential in causing altered scototaxis and bottom-dwelling behaviour in zebrafish, as well as the usage of silibinin and naringenin as potential neuroprotectants.

Polylactic acid (PLA) has become one of the most commonly used polymers in medical devices given its biocompatible, biodegradable and bioabsorbable properties. In addition, due to PLA’s thermoplastic behaviour, these medical devices are now obtained using 3D printing technologies. Once obtained, the 3D-printed PLA devices undergo different sterilisation procedures, which are essential to prevent infections. This work was an in-depth study of the physicochemical changes caused by novel and conventional sterilisation techniques on 3D-printed PLA and their impact on the biological response in terms of toxicity. The 3D-printed PLA physicochemical (XPS, FTIR, DSC, XRD) and mechanical properties as well as the hydrophilic degree were evaluated after sterilisation using saturated steam (SS), low temperature steam with formaldehyde (LTSF), gamma irradiation (GR), hydrogen peroxide gas plasma (HPGP) and CO2 under critical conditions (SCCO). The biological response was tested in vitro (fibroblasts NCTC-929) and in vivo (embryos and larvae wild-type zebrafish Danio rerio). The results indicated that after GR sterilisation, PLA preserved the O:C ratio and the semi-crystalline structure. Significant changes in the polymer surface were found after HPGP, LTSF and SS sterilisations, with a decrease in the O:C ratio. Moreover, the FTIR, DSC and XRD analysis revealed PLA crystallisation after SS sterilisation, with a 52.9% increase in the crystallinity index. This structural change was also reflected in the mechanical properties and wettability. An increase in crystallinity was also observed after SCCO and LTSF sterilisations, although to a lesser extent. Despite these changes, the biological evaluation revealed that none of the techniques were shown to promote the release of toxic compounds or PLA modifications with toxicity effects. GR sterilisation was concluded as the least reactive technique with good perspectives in the biological response, not only at the level of toxicity but at all levels, since the 3D-printed PLA remained almost unaltered.

To discover new molecules or review the biological activity and toxicity of therapeutic substances, drug development, and research relies on robust biological systems to obtain reliable results. Phenotype-based screenings can transpose the organism’s compensatory pathways by adopting multi-target strategies for treating complex diseases, and zebrafish emerged as an important model for biomedical research and drug screenings. Zebrafish’s clear correlation between neuro-anatomical and physiological features and behavior is very similar to that verified in mammals, enabling the construction of reliable and relevant experimental models for neurological disorders research. Zebrafish presents highly conserved physiological pathways that are found in higher vertebrates, including mammals, along with a robust behavioral repertoire. Moreover, it is very sensitive to pharmacological/environmental manipulations, and these behavioral phenotypes are detected in both larvae and adults. These advantages align with the 3Rs concept and qualify the zebrafish as a powerful tool for drug screenings and pre-clinical trials. This review highlights important behavioral domains studied in zebrafish larvae and their neurotransmitter systems and summarizes currently used techniques to evaluate and quantify zebrafish larvae behavior in laboratory studies.

La plastica è un materiale unico per i suoi numerosi vantaggi, tra cui l’essere economico, versatile, leggero, flessibile e resistente. Sono proprio queste indubbie qualità ad aver fatto crescere esponenzialmente la produzione dei polimeri plastici negli ultimi 70 anni, dando vita parallelamente ad una nuova minaccia ambientale, causata soprattutto dalla inadeguata gestione dei rifiuti plastici, la cui maggior parte viene tutt’ora abbandonata in discarica, se non rilasciata direttamente in ambiente. I rischi della dispersione della plastica negli ecosistemi aumentano quando si fa riferimento ai frammenti di minor dimensione, sia derivanti dalla degradazione di macroplastiche sia appositamente prodotti per applicazioni industriali. Infatti, una ridotta dimensione può aumentare la capacità dei frammenti plastici di accumularsi a livello dei tessuti degli organismi, ma anche di agire da vettori di contaminanti chimici. Lo scopo del progetto è stato valutare l’impatto ambientale dovuto alla presenza delle micro- e delle nanoplastiche, attraverso l’esposizione di specie acquatiche e terrestri e l’osservazione dei potenziali effetti ai diversi livelli dell’organizzazione biologica. Sono stati condotti diversi esperimenti di laboratorio utilizzando sia specie modello d’acqua dolce, Danio rerio e Dreissena polymorpha, che, per la prima volta, un modello terrestre, il baco da seta Bombyx mori. È stato inoltre approfondito il ruolo delle plastiche come carrier di contaminanti ambientali. In tutti gli organismi è stato dimostrato l’accumulo delle plastiche e la conseguente infiltrazione nei diversi tessuti. Le analisi biochimiche hanno evidenziato lievi effetti dell’esposizione a micro- e nanoplastiche, mentre risultati più rilevanti e da approfondire sono emersi dai test comportamentali. Gli effetti a livello individuale, uniti alle analisi di proteomica, hanno inoltre indicato un cambiamento della tossicità di plastiche e contaminanti chimici quando amministrati in combinazione, invece che singolarmente, suggerendo una relazione ben più complicata che un semplice effetto additivo o sinergico. Lo studio ha infine aperto le porte all’utilizzo delle larve di B. mori come organismo modello per la valutazione degli effetti dei frammenti di plastica su organismi terrestri, ancora ampiamente sconosciuti.
The uniqueness of plastic is given by its several advantages, including low cost, lightweight, flexibility and resistance. These properties exponentially increased the global demand for plastic in the last 70 years, turning this revolutionary material into a global environmental threat. Indeed, the mismanagement of plastic waste, most of which is still sent to landfills or directly littered in the environment by human improper behaviour, is becoming a serious threat for ecosystems. The effects of plastic dispersal in the environment potentially increase when considering the fragments of smaller dimension, which derive from the degradation of macroplastics or are intentionally produced for industrial applications. A lower dimension may therefore enhance the plastic fragment capacity to accumulate at tissue level, but also to act as vector for chemical contaminants. The project was aimed at evaluating the environmental impact due to the presence of micro- and nanoplastics, exposing aquatic and terrestrial species and observing the potential adverse effects using multi-tiered approaches. Several laboratory experiments were conducted using both freshwater model species, the vertebrate Danio rerio and the invertebrate Dreissena polymorpha, and, for the first time, the terrestrial model Bombyx mori. Moreover, the role of plastics as carrier of environmental contaminants was investigated on zebrafish larvae. All organisms showed the accumulation of plastics and their infiltration in different tissues. The biochemical analyses highlighted only slight effects of micro- and nanoplastic exposures, while more relevant results emerged from behavioural tests, which deserve further studies. Furthermore, the effects at individual level, combined with proteomic analyses, pointed out a shift in the toxicity of plastics and chemical contaminants when co- administered, suggesting a more complicated relationship then an additive or synergistic effect. Finally, the study paves the way for the use of B. mori larva as model organism for the evaluation of the effects of plastic particles on terrestrial ecosystems, which are still largely unknown.

Mestrado em Toxicologia e Ecotoxicologia
Os fármacos são atualmente considerados contaminantes ambientais emergentes, devido à sua constante deteção nos ecossistemas aquáticos, consequência do aumento na sua produção, diversificação e consumo. A carbamazepina (Cbz) é um fármaco humano utilizado para tratamento de epilepsia, distúrbios bipolares e neuralgia trigeminal estando entre os fármacos mais prescritos no mundo e sendo considerado um marcador de poluição antropogénica. Para uma correta avaliação de risco ambiental é essencial avaliar os efeitos a longo termo dos compostos em vários níveis de organização biológica. Assim, os objetivos deste trabalho foram: i) avaliar a toxicidade crónica da Cbz para o peixe-zebra (Danio rerio) adulto, numa gama de concentrações que inclui uma concentração ambientalmente relevante (10 μg.L−1) e uma concentração correspondente a 5% do valor de concentração letal mediana (CL50) (10000 μg.L−1). Foram estudados efeitos no crescimento, comportamento alimentar, reprodução (número total de ovos e viabilidade), defesas antioxidantes (atividade da catalase - CAT e Glutationa S- transferase - GST), neurotransmissão (atividade da acetilcolinesterase - AChE), atividade metabólica (atividade da lactato desidrogenase - LDH) e anomalias nucleares eritrocíticas nos adultos expostos a Cbz; ii) avaliar a toxicidade aguda do propranolol (Prop) (um fármaco cardiovascular utilizado no controlo da hipertensão, angina pectoris e arritmia após enfarte agudo do miocárdio) para adulto D. rerio após previa exposição a Cbz, iii) avaliar alterações na suscetibilidade de embriões decorrente da exposição aguda ao Prop após exposição parental a Cbz. A exposição crónica do peixe-zebra a Cbz induziu alterações no tempo total de ingestão de alimento nas duas concentrações testadas e induziu inibição da CAT no fígado e brânquias (10 e 10000 μg.L−1). A GST apresentou uma resposta dependente do órgão, com um aumento de atividade nas brânquias (10 e 10000 μg.L−1) e fígado (10000 μg.L−1) e diminuição no intestino (10000 μg.L−1). A atividade da AChE aumentou na cabeça (10 e 10000 μg.L−1) e músculo (10000 μg.L−1), enquanto a atividade da LDH apresentou-se aumentada no fígado (10000 μg.L−1) e diminuída no músculo e brânquias na concentração de Cbz mais elevada (10000 μg.L−1). Em termos reprodutivos, a Cbz (10 e 10000 μg.L−1) diminuiu o número de ovos viáveis produzidos por peixe-zebra. A prévia exposição de adulto D. rerio a baixas concentrações de Cbz (0 e 10 μg.L−1) induziu 100% de mortalidade quando os organismos foram expostos ao Prop (1000 e 5000 μg.L−1) enquanto, organismos expostos a maior concentração de Cbz (10000 μg.L−1) apresentaram capacidade para tolerar o Prop. A exposição crónica a Cbz não teve no entanto efeitos significativos na taxa de crescimento dos organismos, não tendo igualmente sido detectadas anomalias nucleares eritrocíticas, indicadores de cito e genotoxicidade. Os descendentes não demonstraram alterações na susceptibilidade ao Prop, quando comparados com os organismos controlo. De uma forma geral, os dados obtidos neste trabalho sugerem que a exposição crónica a baixas concentrações de Cbz afeta o comportamento e processos bioquímicos no peixe-zebra com possíveis consequências a nível da reprodução.
Pharmaceuticals are emerging environmental contaminants due to their constant detection into aquatic ecosystems, as a response to the increase in the rate of production, high diversity, and high consumption. Carbamazepine (Cbz) is used to epilepsy treatment, bipolar disorders, trigeminal neuralgia, being among the most prescribed drugs in the world and is considered a marker of anthropogenic pollution. For a correct environmental risk assessment, it is essential to evaluate the long-term effects of the compounds in various levels of biological organization. The objectives of this study were: i) evaluate the chronic toxicity (63 days) of Cbz for adult Danio rerio at an environmentally relevant concentration (10 μg.L-1) and at a concentration close to 5% of the median lethal concentration (LC50) value (10000 μg.L-1). Effects were studied on growth, feeding behavior, reproduction (total number of eggs and viability), antioxidant defences (Catalase - CAT and Glutathione-S-Transferase - GST), neurotransmission (acetylcholinesterase activity – AChE), metabolic activity (lactate dehydrogenase - LDH) and nuclear abnormalities in adults exposed to Cbz; ii) to evaluate the acute toxicity of propranolol (Prop) (a cardiovascular pharmaceutical used to hypertension control, angina pectoris and arrhythmia after acute myocardial infarction) for adult D. rerio after chronic exposure to Cbz, iii) to evaluate changes in offspring susceptibility to acute exposure to Prop after parental exposure to Cbz and, in offspring. Chronic exposure of zebrafish to Cbz induced changes in total time for food intake at the two concentrations tested. Cbz exposure induced changes in enzymatic activity: CAT was inhibited in the liver and gills (10 and 10000 μg.L-1); GST presented an organ-dependent response with increased activity in the gills (10 and 10000 μg.L-1) and in the liver (10000 μg.L-1) and a decrease in enzyme activity in the intestine (10000 μg.L-1); the activity of AChE was increased in head (10 and 10000 μg.L-1) and muscle (10000 μg.L-1); while LDH showed increased activity in the liver and decreased in muscle and gills, these effects were observed in the highest concentration of Cbz (10000 μg.L-1). The number of eggs produced did not suffer changes; however, the number of viable eggs produced by zebrafish, exposed to Cbz was reduced (10 and 10000 μg.L-1). The previous exposure of adult D. rerio to low concentrations of Cbz (0 and 10 μg.L-1) induced mortality of 100% when these organisms were exposed to Prop (1000 and 5000 μg.L-1) while organisms exposed to a higher concentration of Cbz (10000 μg.L-1) were able to tolerate the Prop.The chronic exposure to Cbz did not induced significant effects in growth rate of the organisms and no erythrocytic nuclear abnormalities, cito and genotoxicity indicators were detected. The offspring did not show changes in Prop susceptibility, when compared with the control organisms. Overall, the data obtained in this work suggest that chronic exposure to low concentration of Cbz affects feeding behaviour and biochemical processes in zebrafish with possible consequences at reproduction level.

Billions of pounds of bisphenol A (BPA) are produced annually around the globe for the manufacture of numerous consumer products, including polycarbonate food and water containers, the protective resin linings of food cans, thermal printing paper, and dental fillings. BPA exposure during nervous system development has been associated with learning and behavioral impairments in animal models. The mode of action for these effects is not clearly defined. While BPA is a weak estrogen receptor (ER) agonist, it is also an estrogen-related receptor gamma (ERR��) agonist. ERR�� binds BPA with 100 times greater affinity than ERs. This study was designed to test the hypothesis that exposure to human-relevant BPA concentrations impacts nervous system development and behavior through ERR�� activation. To examine whether BPA behaves more like an ER or ERR�� ligand, two positive control compounds were used throughout the study: 17��-estradiol (E2) and GSK4716, ER and ERR�� agonists, respectively. Initial behavior testing results included the observation that neurodevelopmental exposure to 0.01 or 0.1 ��M BPA led to hyperactivity in larvae, while exposure to 0.1 or 1 ��M BPA led to learning deficits in adult zebrafish. Exposure to 0.1 ��M E2 or GSK4716 also led to larval hyperactivity. To identify early molecular signaling events that lead to the observed neurobehavioral phenotypes, a global gene expression analysis using a 135K zebrafish microarray was conducted. The concentrations of compounds tested were anchored to the common larval hyperactivity phenotype they elicited. Gross abnormalities, in the case of higher concentrations of BPA and E2, were also anchored phenotypes included in the analysis. Functional pathway analysis of the BPA versus E2 results predicted an impact on prothrombin signaling from the two lower concentrations of BPA and E2. Both BPA and GSK4716 were also predicted to impact nervous system development, potentially involving inhibition of the upstream regulator, SIM1. Additionally, GSK4716 exposure was predicted to inhibit neuron migration. There were fewer similarities in transcriptional responses between BPA and E2 when the lower versus higher concentrations were compared, suggesting different mechanisms operated at the higher concentrations. Subsequent experiments were focused on the role of ERR�� in the larval hyperactivity phenotype. Transient ERR�� knockdown by antisense oligonucleotide morpholino during the first 24 hours of development abrogated the hyperactive phenotype induced by 0.1 ��M BPA exposure. Transient ERR�� knockdown during the first 48 hours of development resulted in developmental delays, craniofacial defects, pericardial edema, and severe body axis curvature. This work is the first to identify behavioral effects in a fish from developmental BPA exposure. It is also the first study to confirm a role for ERR�� in mediating BPA's neurobehavioral effects in any animal model. The global gene expression analysis identified similarities between BPA, E2, and GSK4716, suggesting that BPA's mode of action may involve crosstalk between ERR�� and other ERs. These results from human-relevant BPA exposures help explain the widely documented in vivo effects of BPA, despite low binding affinity exhibited by nuclear ERs. ERR�� is an evolutionarily conserved vertebrate receptor and the developmental impacts of BPA in the zebrafish are an indication of hazard potential to vertebrates. They are also an important translational step toward knowing the hazard potential from human developmental exposure to BPA and yet unknown environmental ligands of ERR��.
Graduation date: 2013
Access restricted to the OSU Community, at author's request, from Dec. 21, 2012 - June 21, 2013

碩士
國立交通大學
環境工程系所
104
The increasing amount of fullerene (C60) released in aqueous environments as the result of its growing use has arisen concerns over its environmental fate. In the water, C60 can form stable, nanoscale and suspended aggregates (nC60) which might possess altered toxicity after its interaction with environmental components, such as ubiquitous natural organic matter (NOM) and clay minerals. Consequently, careful characterization of nC60 physicochemical properties in the natural aqueous environment is required in evaluating its toxicity. This study investigated the effects of humic acid (HA), fulvic acid (FA) and kaolin with various pH values and ionic strengths on the formation of nC60 — produced by solvent exchange (Tol/nC60) — in terms of suspended concentration, aggregate size, and zeta potential. Zebrafish (Danio rerio) embryo was used to study the developmental toxicity of nC60 with disparate physicochemical properties. The results have indicated that increased nC60 aggregation with decreasing pH value or increasing ionic strength, which is attributed to decreased electrostatic repulsion, consistent with the classical DLVO theory. NOM sterically has stabilized the nC60 suspension therefore it is easily formed and stable even at pH 3 or low ionic strength (10 mM NaCl). Besides, HA is more effective than FA in suppressing nC60 aggregation. Interactions between nC60 and clay minerals are primarily dominated by available surface area and electrostatic interaction at charged surfaces. As a result, more nC60 is suspended in the presence of clay minerals under low turbidity (2 ~ 100 NTU) than high turbidity (> 100 NTU). In addition, 20 to 35 mg/L of nC60 may cause hatching delay in zebrafish embryos but no mortality and malformation have been observed. With increasing humic acid concentrations, malformation rate has been found to slightly increase in dechorionated embryos. The major development abnormality caused by nC60 is pericardial edema. In conclusion, in the presence of NOM, the physicochemical properties of nC60 play a significant role in their reactions and subsequent zebrafish embryonic toxicity.