Your browser doesn't support javascript.
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 3.226
Filtrar
Mais filtros










Intervalo de ano de publicação
1.
Adv Exp Med Biol ; 1131: 901-942, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-31646539

RESUMO

The zebrafish (Danio rerio) has emerged as a widely used model system during the last four decades. The fact that the zebrafish larva is transparent enables sophisticated in vivo imaging, including calcium imaging of intracellular transients in many different tissues. While being a vertebrate, the reduced complexity of its nervous system and small size make it possible to follow large-scale activity in the whole brain. Its genome is sequenced and many genetic and molecular tools have been developed that simplify the study of gene function in health and disease. Since the mid 90's, the development and neuronal function of the embryonic, larval, and later, adult zebrafish have been studied using calcium imaging methods. This updated chapter is reviewing the advances in methods and research findings of zebrafish calcium imaging during the last decade. The choice of calcium indicator depends on the desired number of cells to study and cell accessibility. Synthetic calcium indicators, conjugated to dextrans and acetoxymethyl (AM) esters, are still used to label specific neuronal cell types in the hindbrain and the olfactory system. However, genetically encoded calcium indicators, such as aequorin and the GCaMP family of indicators, expressed in various tissues by the use of cell-specific promoters, are now the choice for most applications, including brain-wide imaging. Calcium imaging in the zebrafish has contributed greatly to our understanding of basic biological principles during development and adulthood, and the function of disease-related genes in a vertebrate system.


Assuntos
Cálcio , Peixe-Zebra , Animais , Encéfalo/diagnóstico por imagem , Cálcio/metabolismo , Modelos Animais , Neurônios/fisiologia , Peixe-Zebra/fisiologia
2.
Ying Yong Sheng Tai Xue Bao ; 30(8): 2845-2853, 2019 Aug.
Artigo em Chinês | MEDLINE | ID: mdl-31418211

RESUMO

The safety of feed derived from genetically modified (GM) crops is one of the focuses of attention. To evaluate the ecotoxicological effects of transgenic mCry1Ac maize (BT799) on fish, zebrafish (Danio rerio) were fed extruded feeds containing either 20% GM maize (GMF) or its parental control maize (PF), GM maize meal (GMM) or its parental control maize meal (PMM), and a control commercial feed (CF), respectively. The growth performance, histopathology, reproduction, antioxidant enzyme activity and mRNA expression levels of sensitive protein in the liver were investigated over the course of a 98-day feeding trial. The results showed that transgenic mCry1Ac maize had no significant effect on growth, histopathology of the liver, brain and intestinal tract, fecundity, hatching rate of fertilized eggs, superoxide dismutase (SOD), catalase (CAT) activity, mRNA expression levels of SOD and CAT, or heat shock protein 70 (HSP70) and vitellogenin (VTG) in the liver. However, zebrafish fed the commercial feed exhibited significantly greater weight, longer length, and higher specific growth rate than those fed feeds (GMF and PF) and maize meals (GMM and PMM). The hatching rate of zebrafish in the feed groups was significantly lower than that of the maize meal groups and the commercial feed group. The mRNA transcriptional levels of VTG were significantly higher in the liver for the feed groups (3.85±0.76) than that for the maize meal groups (1.60±0.56). These results suggest that transgenic mCry1Ac maize has no ecotoxicological effects on zebrafish. However, the differences in nutrient composition and palatability between the extruded experimental feeds and the commercial feed would lead to significant diffe-rences in some parameters.


Assuntos
Alimentos Geneticamente Modificados , Zea mays/genética , Ração Animal , Animais , Plantas Geneticamente Modificadas , Testes de Toxicidade , Peixe-Zebra/fisiologia
3.
Nat Commun ; 10(1): 3053, 2019 07 16.
Artigo em Inglês | MEDLINE | ID: mdl-31311924

RESUMO

The germline is the only cellular lineage capable of transferring genetic information from one generation to the next. Intergenerational transmission of epigenetic memory through the germline, in the form of DNA methylation, has been proposed; however, in mammals this is largely prevented by extensive epigenetic erasure during germline definition. Here we report that, unlike mammals, the continuously-defined 'preformed' germline of zebrafish does not undergo genome-wide erasure of DNA methylation during development. Our analysis also uncovers oocyte-specific germline amplification and demethylation of an 11.5-kb repeat region encoding 45S ribosomal RNA (fem-rDNA). The peak of fem-rDNA amplification coincides with the initial expansion of stage IB oocytes, the poly-nucleolar cell type responsible for zebrafish feminisation. Given that fem-rDNA overlaps with the only zebrafish locus identified thus far as sex-linked, we hypothesise fem-rDNA expansion could be intrinsic to sex determination in this species.


Assuntos
Metilação de DNA/fisiologia , DNA Ribossômico/metabolismo , Regulação da Expressão Gênica no Desenvolvimento/fisiologia , Oócitos/metabolismo , Peixe-Zebra/fisiologia , Animais , Desmetilação , Epigênese Genética/fisiologia , Feminino , Masculino , RNA Ribossômico/genética , Caracteres Sexuais
4.
Nature ; 571(7764): 198-204, 2019 07.
Artigo em Inglês | MEDLINE | ID: mdl-31292557

RESUMO

Slow-wave sleep and rapid eye movement (or paradoxical) sleep have been found in mammals, birds and lizards, but it is unclear whether these neuronal signatures are found in non-amniotic vertebrates. Here we develop non-invasive fluorescence-based polysomnography for zebrafish, and show-using unbiased, brain-wide activity recording coupled with assessment of eye movement, muscle dynamics and heart rate-that there are at least two major sleep signatures in zebrafish. These signatures, which we term slow bursting sleep and propagating wave sleep, share commonalities with those of slow-wave sleep and paradoxical or rapid eye movement sleep, respectively. Further, we find that melanin-concentrating hormone signalling (which is involved in mammalian sleep) also regulates propagating wave sleep signatures and the overall amount of sleep in zebrafish, probably via activation of ependymal cells. These observations suggest that common neural signatures of sleep may have emerged in the vertebrate brain over 450 million years ago.


Assuntos
Neurônios/fisiologia , Sono/fisiologia , Peixe-Zebra/fisiologia , Animais , Evolução Biológica , Encéfalo/citologia , Encéfalo/efeitos dos fármacos , Encéfalo/fisiologia , Encéfalo/fisiopatologia , Epêndima/citologia , Movimentos Oculares , Fluorescência , Frequência Cardíaca , Hipnóticos e Sedativos/farmacologia , Hormônios Hipotalâmicos/metabolismo , Melaninas/metabolismo , Neurônios/efeitos dos fármacos , Pigmentação/fisiologia , Hormônios Hipofisários/metabolismo , Polissonografia/métodos , Sono/efeitos dos fármacos , Privação do Sono/fisiopatologia , Sono REM/efeitos dos fármacos , Sono REM/fisiologia , Sono de Ondas Lentas/efeitos dos fármacos , Sono de Ondas Lentas/fisiologia
5.
Neuron ; 103(1): 118-132.e7, 2019 07 03.
Artigo em Inglês | MEDLINE | ID: mdl-31147153

RESUMO

Animals use global image motion cues to actively stabilize their position by compensatory movements. Neurons in the zebrafish pretectum distinguish different optic flow patterns, e.g., rotation and translation, to drive appropriate behaviors. Combining functional imaging and morphological reconstruction of single cells, we revealed critical neuroanatomical features of this sensorimotor transformation. Terminals of direction-selective retinal ganglion cells (DS-RGCs) are located within the pretectal retinal arborization field 5 (AF5), where they meet dendrites of pretectal neurons with simple tuning to monocular optic flow. Translation-selective neurons, which respond selectively to optic flow in the same direction for both eyes, are intermingled with these simple cells but do not receive inputs from DS-RGCs. Mutually exclusive populations of pretectal projection neurons innervate either the reticular formation or the cerebellum, which in turn control motor responses. We posit that local computations in a defined pretectal circuit transform optic flow signals into neural commands driving optomotor behavior. VIDEO ABSTRACT.


Assuntos
Fluxo Óptico/fisiologia , Vias Visuais/citologia , Animais , Cerebelo/citologia , Cerebelo/fisiologia , Dendritos/fisiologia , Neurópilo/fisiologia , Neurópilo/ultraestrutura , Terminações Pré-Sinápticas/fisiologia , Formação Reticular/citologia , Formação Reticular/fisiologia , Células Ganglionares da Retina/fisiologia , Colículos Superiores/citologia , Colículos Superiores/fisiologia , Visão Binocular/fisiologia , Visão Monocular/fisiologia , Vias Visuais/anatomia & histologia , Peixe-Zebra/fisiologia
6.
Aquat Toxicol ; 213: 105227, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31226596

RESUMO

The environmental impact of exposure to 3D-printed plastics as well as potential migration of toxic chemicals from 3D-printed plastics remains largely unexplored. In this work we applied leachates from plastics fabricated using a stereolithography (SLA) process to early developmental stages of zebrafish (Danio rerio) to investigate developmental toxicity and neurotoxicity. Migration of unpolymerized photoinitiator, 1-hydroxycyclohexyl phenyl ketone (1-HCHPK) from a plastic solid phase to aqueous media at up to 200 mg/L in the first 24 h was detected using gas chromatography-mass spectrometry. Both plastic extracts (LC50 22.25% v/v) and 1-HCHPK (LC50 60 mg/L) induced mortality and teratogenicity within 48 h of exposure. Developmental toxicity correlated with in situ generation of reactive oxygen species (ROS), an increase in lipid peroxidation and protein carbonylation markers and enhanced activity of superoxide dismutase (SOD) and glutathione-S-transferase (GST) in embryos exposed to concentrations as low as 20% v/v for plastic extracts and 16 mg/L for 1-HCHPK. ROS-induced cellular damage led to induction of caspase-dependent apoptosis which could be pharmacologically inhibited with both antioxidant ascorbic acid and a pan-caspase inhibitor. Neuro-behavioral analysis showed that exposure to plastic leachates reduced spontaneous embryonic movement in 24-36 hpf embryos. Plastic extracts in concentrations above 20% v/v induced rapid retardation of locomotion, changes in photomotor response and habituation to photic stimuli with progressive paralysis in 120 hpf larvae. Significantly decreased acetylcholinesterase (AChE) activity with lack of any CNS-specific apoptotic phenotypes as well as lack of changes in motor neuron density, axonal growth, muscle segment integrity or presence of myoseptal defects were detected upon exposure to plastic extracts during embryogenesis. Considering implications of the results for environmental risk assessment and the growing usage of 3D-printing technologies, we speculate that some 3D-printed plastic waste may represent a significant and yet very poorly uncharacterized environmental hazard that merits further investigation on a range of aquatic and terrestrial species.


Assuntos
Comportamento Animal , Sistema Nervoso/efeitos dos fármacos , Plásticos/toxicidade , Impressão Tridimensional , Testes de Toxicidade , Peixe-Zebra/fisiologia , Acetilcolinesterase/metabolismo , Animais , Antioxidantes/metabolismo , Apoptose/efeitos dos fármacos , Comportamento Animal/efeitos dos fármacos , Biomarcadores/metabolismo , Embrião não Mamífero/efeitos dos fármacos , Embrião não Mamífero/metabolismo , Desenvolvimento Embrionário/efeitos dos fármacos , Glutationa Transferase/metabolismo , Larva/efeitos dos fármacos , Larva/metabolismo , Neurônios Motores/efeitos dos fármacos , Neurônios Motores/metabolismo , Desenvolvimento Muscular/efeitos dos fármacos , Estresse Oxidativo/efeitos dos fármacos , Espécies Reativas de Oxigênio/metabolismo , Superóxido Dismutase/metabolismo , Poluentes Químicos da Água/toxicidade , Peixe-Zebra/embriologia
7.
Aquat Toxicol ; 213: 105226, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31229889

RESUMO

Zebrafish (Danio rerio) is a prominent model organism in a wide range of biological studies including toxicology. However, toxicological studies are often performed at species specific optimum temperature, and knowledge on the effect of different temperature regimes on the toxicity of metal ions is rather limited. To address this knowledge gap, present study investigates the effect of various thermal scenarios (simultaneous and sequential; acute and chronic) on the toxicity of Cu and Cd in zebrafish. For this purpose we assessed mortality and whole body metal burdens as indicators of toxicity and bioavailability, respectively, and whole body electrolyte concentrations and body condition as the indicators of physiological condition. Thermal pre-incubations (for 12 or 96 h or 28 days) and subsequent metal ion exposures (for 10 days) were conducted at 17, 22, 25, 28, 32 and 34 °C. The metal exposures were performed at Cu concentrations of 1.2 µM and Cd concentrations of 0.2 µM, both singly and in binary mixtures. Irrespective of thermal treatments, Cu exposures resulted in greater mortality than Cd exposures at the given concentrations. Moreover, the Cu and Cd mixture indicated a synergistic effect. While acute pre-incubation for 12 or 96 h at elevated temperatures increased mortality in the subsequent metal exposure at the optimum temperature (28 °C), pre-incubation at cold temperatures in this scenario appeared to increase tolerance towards the subsequent metal exposure. Chronic thermal pre-incubation of zebrafish to a range of temperatures for 28 days moderated the effect of temperature fluctuations on subsequent metal toxicity at the optimum temperature. Chronic thermal pre-incubation at a range of temperatures followed by metal exposure at the same temperature showed that environmental temperature variations (higher or lower than optimal temperature) coupled with metal exposure, led to increased mortality, furthermore, the highest whole body metal burdens were measured in this scenario. Nevertheless, neither the whole body burden of metals, nor the metal accumulation rate, were predictors of mortality, i.e. these two values were not higher in dead fish in comparison to those that survived the exposures. Finally, we observed a significant decrease in the whole body Na+ level of dead fish in comparison to fish which survived the exposure conditions, suggesting that survival depends on maintaining Na+ homeostasis under the applied multi-stress conditions. Overall, our results show that thermal pre-history and ambient temperature play an important role in determining the tolerance of zebrafish towards metal ion stress.


Assuntos
Cádmio/toxicidade , Cobre/toxicidade , Exposição Ambiental , Temperatura Ambiente , Peixe-Zebra/fisiologia , Animais , Eletrólitos/metabolismo , Íons , Poluentes Químicos da Água/toxicidade
8.
Neuron ; 103(4): 686-701.e8, 2019 08 21.
Artigo em Inglês | MEDLINE | ID: mdl-31248729

RESUMO

The role of serotonin (5-HT) in sleep is controversial: early studies suggested a sleep-promoting role, but eventually the paradigm shifted toward a wake-promoting function for the serotonergic raphe. Here, we provide evidence from zebrafish and mice that the raphe are critical for the initiation and maintenance of sleep. In zebrafish, genetic ablation of 5-HT production by the raphe reduces sleep, sleep depth, and the homeostatic response to sleep deprivation. Pharmacological inhibition or ablation of the raphe reduces sleep, while optogenetic stimulation increases sleep. Similarly, in mice, ablation of the raphe increases wakefulness and impairs the homeostatic response to sleep deprivation, whereas tonic optogenetic stimulation at a rate similar to baseline activity induces sleep. Interestingly, burst optogenetic stimulation induces wakefulness in accordance with previously described burst activity of the raphe during arousing stimuli. These results indicate that the serotonergic system promotes sleep in both diurnal zebrafish and nocturnal rodents. VIDEO ABSTRACT.


Assuntos
Camundongos/fisiologia , Núcleos da Rafe/fisiologia , Serotonina/fisiologia , Sono/fisiologia , Peixe-Zebra/fisiologia , Animais , Nível de Alerta/genética , Nível de Alerta/fisiologia , Buspirona/farmacologia , Ritmo Circadiano/fisiologia , Fenclonina/farmacologia , Homeostase , Masculino , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Optogenética , Quipazina/farmacologia , Neurônios Serotoninérgicos/efeitos dos fármacos , Neurônios Serotoninérgicos/fisiologia , Serotonina/biossíntese , Antagonistas da Serotonina/farmacologia , Agonistas do Receptor de Serotonina/farmacologia , Privação do Sono/genética , Privação do Sono/fisiopatologia , Triptofano Hidroxilase/deficiência , Triptofano Hidroxilase/genética , Vigília/genética , Vigília/fisiologia , Proteínas de Peixe-Zebra/deficiência , Proteínas de Peixe-Zebra/genética
9.
Ecotoxicol Environ Saf ; 180: 762-769, 2019 Sep 30.
Artigo em Inglês | MEDLINE | ID: mdl-31154201

RESUMO

Alkyl phenanthrene (A-Phen) and Dechlorane Plus (DP) are ubiquitous environmental pollutants that widely co-exist in the environment. It has been established that both A-Phen and DP elicit neurotoxicity, but the potential interactive toxicity of these contaminants is not well-known. To determine whether a mixture of A-Phen and DP would exhibit interactive effects on neurodevelopment, we co-exposed 3-methylphenanthrene (3-MP), a representative of A-Phen, with DP. Our results illustrated that exposure to 5 or 20 µg/L 3-MP alone or in combination with 60 µg/L DP caused neurobehavioral anomalies in zebrafish. In accordance with the behavioral deficits, 3-MP alone or co-exposed with DP significantly decreased axonal growth of secondary motoneurons, altered intracellular Ca2+ homeostasis and induced cell apoptosis in the muscle of zebrafish. Additionally, 3-MP alone or co-exposed with DP significantly increased reactive oxygen species (ROS) and the mRNA levels of apoptosis-related genes. These findings indicate that 3-MP alone or co-exposed with DP induces neurobehavioral deficits through the combined effects on neuronal connectivity and muscle function. Chemical analysis revealed significant increases in 3-MP and DP bioaccumulation in zebrafish co-exposed with 3-MP and DP. Elevated bioaccumulation resulting from mixture exposure may represent a significant contribution of the synergistic effects observed in combined chemical exposure.


Assuntos
Hidrocarbonetos Clorados/toxicidade , Sistema Nervoso/efeitos dos fármacos , Fenantrenos/toxicidade , Compostos Policíclicos/toxicidade , Poluentes Químicos da Água/toxicidade , Peixe-Zebra/fisiologia , Animais , Proteínas Reguladoras de Apoptose/genética , Sinergismo Farmacológico , Sistema Nervoso/crescimento & desenvolvimento , Fenantrenos/síntese química , RNA Mensageiro/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Peixe-Zebra/crescimento & desenvolvimento
10.
Environ Sci Pollut Res Int ; 26(23): 23555-23570, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31203546

RESUMO

Iron (Fe) and manganese (Mn) are metals commonly found at high concentrations in underground water. These metals are essential for the good functioning of living organisms, but high concentrations lead to imbalance, potentiating the appearance of pathologies. This study aimed to evaluate the effect of exposure to naturally occurring metals in groundwater, using zebrafish (Danio rerio) as an experimental model. Thus, zebrafish were exposed to Fe (0.8 and 1.3 mg/L), Mn (0.2 and 0.4 mg/L), and groundwater collected from deep tube wells with Fe and Mn (Fe 0.8/Mn 0.2 mg/L and Fe 1.3/Mn 0.4 mg/L) for 30 days. Bioaccumulation of these metals has been demonstrated in the livers and muscles of zebrafish. Acetylcholinesterase activity changed only in zebrafish muscles in all groups. Sulfhydryl levels changed mainly in the group Mn 0.4. SOD/CAT ratio decreased in the groups Fe 0.8 and 1.3, Mn 0.4, and Fe 0.8/Mn 0.4. An increase in the frequency of micronucleus in all groups was shown as a consequence of these changes. Behavioral parameters (time and distance traveled, mean speed, turn angle, latency, and number of crossings between compartments) have also changed, mainly in the groups Fe 1.3, Mn 0.4, and Fe 1.3/Mn 0.4. Therefore, long-term exposure to Fe and Mn, even at not so high concentrations, may cause biochemical, genotoxic, and behavioral changes in zebrafish.


Assuntos
Ferro/toxicidade , Manganês/toxicidade , Poluentes Químicos da Água/toxicidade , Peixe-Zebra/fisiologia , Animais , Dano ao DNA , Água Subterrânea/química , Ferro/análise , Fígado/efeitos dos fármacos , Manganês/análise , Músculos/química , Poluentes Químicos da Água/análise
11.
Sci Total Environ ; 685: 923-933, 2019 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-31247439

RESUMO

The ecotoxicity of untreated tannery effluent (UTE) in several animal models has been reported; however, its effects on fish behavior, and neurotoxicity, remain unknown. Thus, the hypothesis that the chronic exposure to UTE can induce behavioral changes in adult zebrafish (Danio rerio) representatives, even when it is highly diluted in water, was tested. Animals exposed to 0.1% and 0.3% UTE for 30 days showed behavioral changes in visual social preference tests through their co-specific and antipredator defensive responses, which had indicated neurotoxic actions. Zebrafish exposed to UTE appeared to have not co-specific preference when it is paired with Poecilia sphrenops. In addition, only animals in the control group showed aversive behavior in the presence of the herein used predatory stimulus (Oreochromis niloticus). However, Cr, Na and Mg bioaccumulation was higher in zebrafish exposed to 0.1% and 0.3% UTE, although anxiogenic and anxiolytic effects were not observed in the models exposed to UTE in the novel tank diving or aggressiveness-increase-in-the-mirror tests. This outcome allowed associating the exposure to the pollutant and bioaccumulation with the observed behavioral changes. The present study is pioneer in scientifically evidencing the sublethal impact caused by chronic exposure to UTE in experimental environment simulating realistic aquatic pollution conditions. Accordingly, results in the current research should motivate further investigations to broaden the knowledge about the real magnitude of UTE biological impacts on the aquatic biota.


Assuntos
Comportamento Animal/efeitos dos fármacos , Resíduos Industriais , Curtume , Poluentes Químicos da Água/toxicidade , Peixe-Zebra/fisiologia , Animais , Modelos Biológicos , Testes de Toxicidade
12.
Fish Shellfish Immunol ; 91: 87-98, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31082517

RESUMO

Excessive perfluorooctane sulfonate (PFOS) in natural water ecosystem has the potential to detrimentally affect immune system, but little is known of such effects or underlying mechanisms in fish. In the present study, we evaluated the effects of PFOS on growth performance, organizational microstructure, activities of immune-related enzymes and expressions of immune-related genes in male zebrafish (Danio rerio) exposed to different concentrations of 0, 0.02, 0.04 and 0.08 mg/L of PFOS for 7, 14, and 21 days or cotreatment with PFOS and PDTC to investigate the effects of PFOS on immune system and the potential toxic mechanisms caused by PFOS. The results indicated that PFOS accumulated in livers after exposure, and remarkably elevations were found in three exposure groups compared with the control group at three stages. The growth of the adult zebrafish in the experiments was significantly inhibited, the microstructures of liver were serious damaged. The ROS levels were remarkably increased. The activities of ACP, AKP, and lysozyme were obviously decreased, while the activities of MPO and NF-κB were significantly increased. The expressions of immune-related mRNA were significantly affected. After co-treatment with PFOS and PDTC, the growth inhibition, the morphological damage, the ROS induction, and the expressions of immune-related mRNA were reversed. Taken together, the results indicated that PFOS can significantly inhibit the growth, disturb the immune system by changing the normal structure of liver, the activities of immune-related enzymes, and a series of gene transcriptions involved in immune regulation in liver of male zebrafish. PFOS-induced pro-inflammatory effect of hepatocytes was observed, and the involvement of NF-κB signaling pathway was participated in its action mechanism. These findings provide further evidence that PFOS interferes with the immune regulation of liver of male zebrafish under in vivo conditions.


Assuntos
Ácidos Alcanossulfônicos/toxicidade , Proteínas de Peixes/imunologia , Fluorcarbonetos/toxicidade , Fígado/efeitos dos fármacos , NF-kappa B/imunologia , Poluentes Químicos da Água/toxicidade , Peixe-Zebra/fisiologia , Animais , Relação Dose-Resposta a Droga , Proteínas de Peixes/genética , Fígado/metabolismo , Masculino , NF-kappa B/genética , Distribuição Aleatória , Espécies Reativas de Oxigênio/metabolismo , Transdução de Sinais/efeitos dos fármacos , Tiocarbamatos/toxicidade , Peixe-Zebra/genética , Peixe-Zebra/crescimento & desenvolvimento , Peixe-Zebra/imunologia
13.
Environ Pollut ; 251: 203-211, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31078959

RESUMO

Pyraclostrobin is widely used to control crop diseases, and was reported to be highly toxic to aquatic organisms. The molecular target of pyraclostrobin to fungus is the mitochondrion, but its effect on mitochondria of aquatic organisms has rarely been investigated. In this study, zebrafish larvae at 4 days post fertilization (dpf) were exposed to a range of pyraclostrobin for 96 h to assess its acute toxicity and effects on mitochondria. Pyraclostrobin at 36 µg/L or higher concentrations caused significant influences on larval heart and brain including pericardial edema, brain damage malformations, histological and mitochondrial structural damage of the two organs. The results of RNA-Seq revealed that the transcripts of genes related to oxidative phosphorylation, cardiac muscle contraction, mitochondrion, nervous system development and glutamate receptor activity were significantly influenced by 36 µg/L pyraclostrobin. Further tests showed that pyraclostrobin at 18 and 36 µg/L reduced the concentrations of proteins related to cardiac muscle contraction, impaired cardiac function, inhibited glutamate receptors activities and suppressed locomotor behavior of zebrafish larvae. Negative changes in mitochondrial complex activities, as well as reduced ATP content were also observed in larvae treated with 18 and 36 µg/L pyraclostrobin. These results suggested that pyraclostrobin exposure caused cardiotoxicity and neurotoxicity in zebrafish larvae and mitochondrial dysfunction might be the underlying mechanism of pyraclostrobin toxicity.


Assuntos
Cardiotoxicidade , Sistema Nervoso/efeitos dos fármacos , Estrobilurinas/toxicidade , Poluentes Químicos da Água/toxicidade , Peixe-Zebra/fisiologia , Animais , Larva/efeitos dos fármacos , Mitocôndrias/efeitos dos fármacos , Estresse Oxidativo/efeitos dos fármacos , Peixe-Zebra/metabolismo
14.
Chemosphere ; 228: 649-655, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31063912

RESUMO

Circadian rhythms are fundamental to behavior and physiology of organisms. Flutolanil as a fungicide is toxic to zebrafish embryos. The aims of this study were to determine whether flutolanil would influence circadian rhythms of zebrafish and the mechanism involved. Zebrafish embryos were exposed to flutolanil (0, 0.125, 0.5 and 2 mg/L) for 4 days. Here we report that flutolanil increased the melatonin levels of zebrafish. The mRNA levels of genes related to circadian rhythms were significantly altered. The clock level was significantly increased, but the content of cry1 showed no apparent changes. Moreover, our findings that the level of GH was significantly decreased were consistent with the abnormal development of zebrafish embryos. The expression levels of genes related to development, behavior and reproduction were significantly altered by flutolanil. These results indicate that flutolanil disturbed circadian rhythms of zebrafish primarily by affecting the positive elements, which were at least in partial responsible for abnormal development and behavior of zebrafish. And we speculate that flutolanil is toxic to zebrafish embryos at least in part via dysregulation of circadian rhythms involving clock.


Assuntos
Anilidas/toxicidade , Ritmo Circadiano/efeitos dos fármacos , Melatonina/metabolismo , Peixe-Zebra/embriologia , Animais , Comportamento Animal/efeitos dos fármacos , Proteínas CLOCK/genética , Ritmo Circadiano/genética , Criptocromos/genética , Ecotoxicologia/métodos , Embrião não Mamífero/efeitos dos fármacos , Embrião não Mamífero/fisiologia , Fungicidas Industriais/toxicidade , Regulação da Expressão Gênica no Desenvolvimento/efeitos dos fármacos , Poluentes Químicos da Água/toxicidade , Peixe-Zebra/fisiologia , Proteínas de Peixe-Zebra/genética
15.
BMC Genomics ; 20(1): 341, 2019 May 06.
Artigo em Inglês | MEDLINE | ID: mdl-31060508

RESUMO

BACKGROUND: Elevated water temperature, as is expected through climate change, leads to masculinization in fish species with sexual plasticity, resulting in changes in population dynamics. These changes are one important ecological consequence, contributing to the risk of extinction in small and inbred fish populations under natural conditions, due to male-biased sex ratio. Here we investigated the effect of elevated water temperature during embryogenesis on sex ratio and sex-biased gene expression profiles between two different tissues, namely gonad and caudal fin of adult zebrafish males and females, to gain new insights into the molecular mechanisms underlying sex determination (SD) and colour patterning related to sexual attractiveness. RESULTS: Our study demonstrated sex ratio imbalances with 25.5% more males under high-temperature condition, resulting from gonadal masculinization. The result of transcriptome analysis showed a significantly upregulated expression of male SD genes (e.g. dmrt1, amh, cyp11c1 and sept8b) and downregulation of female SD genes (e.g. zp2.1, vtg1, cyp19a1a and bmp15) in male gonads compared to female gonads. Contrary to expectations, we found highly differential expression of colour pattern (CP) genes in the gonads, suggesting the 'neofunctionalisation' of those genes in the zebrafish reproduction system. However, in the caudal fin, no differential expression of CP genes was identified, suggesting the observed differences in colouration between males and females in adult fish may be due to post-transcriptional regulation of key enzymes involved in pigment synthesis and distribution. CONCLUSIONS: Our study demonstrates male-biased sex ratio under high temperature condition and support a polygenic SD (PSD) system in laboratory zebrafish. We identify a subset of pathways (tight junction, gap junction and apoptosis), enriched for SD and CP genes, which appear to be co-regulated in the same pathway, providing evidence for involvement of those genes in the regulation of phenotypic sexual dimorphism in zebrafish.


Assuntos
Regulação da Expressão Gênica no Desenvolvimento , Gônadas/metabolismo , Diferenciação Sexual , Razão de Masculinidade , Proteínas de Peixe-Zebra/metabolismo , Peixe-Zebra/genética , Animais , Cor , Feminino , Temperatura Alta , Masculino , Maturidade Sexual , Transcriptoma , Peixe-Zebra/fisiologia , Proteínas de Peixe-Zebra/genética
16.
Chemosphere ; 229: 169-180, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31078031

RESUMO

Although silver nanoparticles (AgNPs) are used in various commercial products, the biological effects of AgNPs on fish embryogenesis and the underlying molecular mechanisms are still poorly understood. In this study, both touch responses and neuron membrane potential were found to be abnormal in AgNPs-stressed embryos. Moreover, neurogenesis genes were unveiled to be down-regulated and were enriched in ligand-gated ion channel activity, dopamine receptor signaling pathway, etc. in AgNPs-stressed embryos by microarray assays. Additionally, the down-regulated expression of otpa/sncgb - gad1b/gad2 dopaminergic neurotransmitter genes, robo2 - vim and glrbb synaptic transmission genes, and motor neuron genes isl1 &isl2a was further identified in both AgNPs- and Ag+-stressed embryos by qPCR, whole-mount in situ hybridization (WISH), and by using specific promoter-derived GFP fluorescence transgenic zebrafish. Moreover, the reduced expression of gad1b, gad2, and isl1 could be recovered by adding Ag+ chelating compound l-cysteine in AgNPs stressed embryos. Our results reveal for the first time that it is through damaging the formation of neural circuits, including dopaminergic neurotransmitter, synaptic transmission, and motor activities, that AgNPs induce abnormal electrical membrane properties, leading to dysfunctional touch responses and locomotor escape responses mostly via their released Ag+ during embryogenesis.


Assuntos
Embrião não Mamífero/efeitos dos fármacos , Nanopartículas Metálicas/toxicidade , Fenômenos Fisiológicos do Sistema Nervoso/efeitos dos fármacos , Prata/química , Prata/toxicidade , Tato/efeitos dos fármacos , Peixe-Zebra/embriologia , Animais , Embrião não Mamífero/fisiologia , Tato/fisiologia , Peixe-Zebra/metabolismo , Peixe-Zebra/fisiologia , Proteínas de Peixe-Zebra/genética , Proteínas de Peixe-Zebra/metabolismo
17.
Aquat Toxicol ; 212: 70-76, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31077968

RESUMO

Medroxyprogesterone acetate (MPA) is a widely used synthetic progestin and it has been frequently detected in aquatic environments. However, its effects on aquatic organisms remain largely unknown. Here we investigated the chronic effects of MPA on sex differentiation and gonad development in zebrafish. Zebrafish larvae at 20 days post fertilization (dpf) were exposed to 4.32, 42.0, and 424 ng L-1 of MPA until they reached 140 dpf. The results showed that chronic exposure to 42.0 ng L-1 of MPA caused 60% proportion of males as well as significant up-regulation of dmrt1 (˜1.79 fold) and hsd17b3 (˜1.92 fold). Histological analysis showed MPA significantly increased the frequency of immature spermatocytes accompanied with the increased transcription of dmrt1 (˜2.06 fold) and ar (˜1.73 fold) in the testes. Meanwhile, MPA exposure significantly increased the transcription of lhb at all exposure concentrations in the males. In contrast, it significantly suppressed the transcription of lhb (˜-8.06-fold) and fshb (˜-6.35-fold) at 42.0 ng L-1 in the females. Collectively our results demonstrated that MPA had androgenic activity, and could affect sex differentiation and spermatogenesis in zebrafish at environmentally relevant concentrations. The findings from this study suggest that MPA in the aquatic environment may pose potential androgenic risks to fish populations.


Assuntos
Acetato de Medroxiprogesterona/farmacologia , Diferenciação Sexual/efeitos dos fármacos , Espermatogênese/efeitos dos fármacos , Peixe-Zebra/fisiologia , Animais , Encéfalo/efeitos dos fármacos , Encéfalo/metabolismo , Feminino , Regulação da Expressão Gênica no Desenvolvimento/efeitos dos fármacos , Gônadas/efeitos dos fármacos , Hormônios/sangue , Masculino , Hipófise/efeitos dos fármacos , Hipófise/metabolismo , Razão de Masculinidade , Transcrição Genética/efeitos dos fármacos , Poluentes Químicos da Água/toxicidade , Peixe-Zebra/sangue , Peixe-Zebra/crescimento & desenvolvimento
18.
Nat Neurosci ; 22(7): 1140-1147, 2019 07.
Artigo em Inglês | MEDLINE | ID: mdl-31110322

RESUMO

Most neurons transmit information digitally using spikes that trigger the release of synaptic vesicles with low probability. The first stages of vision and hearing are distinct in that they operate with analog signals, but it is unclear how these are recoded for synaptic transmission. By imaging the release of glutamate in live zebrafish, we demonstrate that ribbon synapses of retinal bipolar cells encode contrast through changes in both the frequency and amplitude of release events. Higher contrasts caused multiple vesicles to be released within an event, and such coding by amplitude often continued after the rate code had reached a maximum frequency. Glutamate packets equivalent to five vesicles transmitted four times as many bits of information per vesicle compared with those released individually. By discretizing analog signals into sequences of numbers up to about 11, ribbon synapses can increase the dynamic range, temporal precision and efficiency with which visual information is transmitted.


Assuntos
Células Bipolares da Retina/fisiologia , Transmissão Sináptica/fisiologia , Vesículas Sinápticas/fisiologia , Vias Visuais/fisiologia , Potenciais de Ação , Animais , Genes Reporter , Ácido Glutâmico/fisiologia , Fusão de Membrana , Técnicas de Patch-Clamp , Detecção de Sinal Psicológico , Peixe-Zebra/fisiologia
19.
Aquat Toxicol ; 212: 194-204, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31132737

RESUMO

Gemfibrozil (GEM) is a fibrate lipid regulator and one of the most commonly occurring fresh water pharmaceuticals. The negative effects of fibrates including GEM on fish reproduction have been frequently reported including effects of F0 GEM exposure on reproduction of the unexposed F1 offspring. We predicted that chronic, direct exposure of zebrafish with low concentrations of GEM would adversely affect parental male reproduction and unexposed offspring for multiple generations. Adult zebrafish were exposed to 10 µg/L GEM for 6 weeks and a range of reproductive indices were analyzed. The F1-F4 offspring were reared in clean water from 3 distinct lineages where only a single or both parents were exposed and compared to a control lineage where parents were unexposed. Reproductive indices were examined in unexposed F1-F4 offspring to test the hypothesis of multi- or trans- generational impacts. Exposure to GEM caused a decline in breeding success and mean embryo production in F0 parents and a reduction in whole body 11-ketotestosterone (11-KT), altered male courtship, aggression and sperm morphology. Our results indicate that paternal exposure alone is sufficient to result in reproductive effects in unexposed male offspring but that effects are mostly limited to F1. We suggest that GEM may act as a reproductive endocrine disruptor in fish and that chronic exposure reduced male reproductive fitness but not over multiple generations.


Assuntos
Exposição Ambiental , Genfibrozila/toxicidade , Reprodução/efeitos dos fármacos , Poluentes Químicos da Água/toxicidade , Peixe-Zebra/fisiologia , Animais , Feminino , Água Doce , Masculino , Comportamento Sexual Animal/efeitos dos fármacos , Testosterona/análogos & derivados , Testosterona/metabolismo
20.
Aquat Toxicol ; 212: 222-232, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31136897

RESUMO

Microcystin-LR (MC-LR) is a highly toxic hepatotoxin that poses great hazards to aquatic organisms and even human health. The zebrafish liver cell line (ZFL) is a valuable model for investigating toxicity and metabolism of toxicants. However, the toxicity of MC-LR and its effects on gene transcription of ZFL cells remains to be characterized. In this study, we determined the toxicity of MC-LR for ZFL cells and investigated the effects of MC-LR on cellular transcriptome dynamics. The EC50 of MC-LR for ZFL cells was 80.123 µg/mL. The ZFL cells were exposed to 10 µg/mL MC-LR for 0, 1, 3, 6, 12 or 24 h, and RNA-sequencing was performed to analyze gene transcription. A total of 10,209 genes were found to be regulated by MC-LR. The numbers of up- and down-regulated genes at different time points ranged from 2179 to 3202 and from 1501 to 2597, respectively. Furthermore, 1543 genes underwent differential splicing (AS) upon MC-LR exposure, of which 620 were not identified as differentially expressed gene (DEG). The effects of MC-LR on cellular functions were highly time-dependent. MAPK (mitogen-activated protein kinase) and FoxO (forkhead box O) signaling pathways were the most prominent pathways activated by MC-LR. Steroid biosynthesis and terpenoid backbone biosynthesis were the most enriched for the down-regulated genes. A gene regulatory network was constructed from the expression profile datasets and the candidate master transcription factors were identified. Our results shed light on the molecular mechanisms of MC-LR cellular toxicity and the transcriptome landscapes of ZFL cells upon MC-LR toxicity.


Assuntos
Microcistinas/toxicidade , Transdução de Sinais/efeitos dos fármacos , Transcriptoma/efeitos dos fármacos , Animais , Linhagem Celular , Regulação para Baixo/efeitos dos fármacos , Hepatócitos/efeitos dos fármacos , Humanos , Concentração Inibidora 50 , Fígado/citologia , Fígado/efeitos dos fármacos , Proteínas Quinases Ativadas por Mitógeno/metabolismo , Poluentes Químicos da Água/toxicidade , Peixe-Zebra/fisiologia
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA