Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 3.647
Filtrar
2.
Aquat Toxicol ; 227: 105608, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32858424

RESUMO

As a feed additive in agriculture, the antibiotic oxytetracycline (OTC) has become widely distributed in the natural environment, leading to the exposure of many organisms to low doses of OTC. Although OTC is clinically contraindicated in children because of its multiple side effects, the effect of exposure to low doses of environmental OTC on children is unknown, particularly during development. In this study, we investigated the effects of OTC on the thyroid endocrine system in zebrafish, through determinations of the whole-body contents of triiodothyronine (T3), thyroxine (T4), and thyroid-stimulating hormone (TSH) by enzyme-linked immunosorbent assay, and analysis of the mRNA expression of regulatory genes involved in the hypothalamus-pituitary-thyroid (HPT) axis using quantitative real-time polymerase chain reaction. Zebrafish embryos were exposed to OTC at environmentally relevant concentrations from 2 h to 120 days post-fertilisation. After exposure to OTC at 1,000 and 5,000 ng/L, T3 contents were significantly enhanced (37.8% and 45.1%, respectively) and TSH contents were reduced (16% and 16.3%, respectively) compared with those in the controls. The OTC-driven increase in the transcription of genes involved in thyroid synthesis (tpo and nis) may be responsible for the altered T3 levels. These data indicate that OTC may cause thyroid dysfunction and lead to reduced TSH secretion owing to enhanced negative feedback control of the HPT axis. Meanwhile, a decrease in body length, weight, and BMI and an increase in heart rate were observed with increasing OTC exposure. In conclusion, our results indicate that long-term exposure to low concentrations of OTC may alter the transcription of key genes involved in the HPT axis, as well as T3 and TSH contents, thereby disrupting the thyroid system and affecting the growth and development of zebrafish.


Assuntos
Oxitetraciclina/toxicidade , Glândula Tireoide/efeitos dos fármacos , Poluentes Químicos da Água/toxicidade , Peixe-Zebra/fisiologia , Animais , Disruptores Endócrinos/toxicidade , Tireotropina , Tiroxina/metabolismo , Tri-Iodotironina/metabolismo
3.
Aquat Toxicol ; 227: 105607, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32861022

RESUMO

The ubiquitous contamination of environmental lead (Pb) remains a worldwide threat. Improper Pb mine waste disposal from an abandoned lead-zinc mine has recently unearthed widespread Pb poisoning in children in Kabwe Zambia. Although the adverse effects of Pb on human health have begun to receive attention, the ecotoxicological effects on aquatic vertebrates still need further investigation. In addition, there is paucity in the knowledge on the behavioural and molecular subcellular responses in larval zebrafish exposed to Pb within the range of environmental relevant concentration (average 3 µg/L with maximum of 94 µg/L) on aquatic organisms such as zebrafish. The adverse effects of environmentally relevant levels of Pb on larval zebrafish was evaluated by measuring swimming behaviour under alternating dark and light conditions. Larval zebrafish acutely exposed to environmentally relevant Pb exhibited neuro-behavioural alteration including enhanced hyperactivity under light conditions evidenced by increased distanced covered and speed compared to the control. The alteration of entire behavioral profiles was further associated with the disturbed expression patterns of mRNA level of key genes associated with antioxidant (HO-1, Ucp-2 and CoxI), proapoptotic gene (TP53), and antiapoptotic gene (Bcl-2). To our knowledge, this is the first report on the effects of environmentally relevant Pb levels from Kabwe, Zambia and their adverse neurobehavioural effects and subcellular molecular oxidative responses in larval zebrafish acutely exposed within a 30 min period. The current results would be beneficial in our understanding of the effects of low Pb levels acutely discharged into an aquatic environment and the life of aquatic organisms.


Assuntos
Chumbo/toxicidade , Poluentes Químicos da Água/toxicidade , Peixe-Zebra/fisiologia , Animais , Antioxidantes/metabolismo , Apoptose/efeitos dos fármacos , Humanos , Larva/efeitos dos fármacos , Estresse Oxidativo/efeitos dos fármacos , Testes de Toxicidade Aguda
4.
Aquat Toxicol ; 225: 105547, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32623180

RESUMO

Some chemicals in the environment disrupt thyroid hormone (TH) systems leading to alterations in organism development, but their effect mechanisms are poorly understood. In fish, this has been limited by a lack of fundamental knowledge on thyroid gene ontogeny and tissue expression in early life stages. Here we established detailed expression profiles for a suite of genes in the hypothalamic-pituitary-thyroid (HPT) axis of zebrafish (Danio rerio) between 24-120 h post fertilisation (hpf) and quantified their responses following exposure to 3,3',5-triiodo-L-thyronine (T3) using whole mount in situ hybridisation (WISH) and qRT-PCR (using whole-body extracts). All of the selected genes in the HPT axis demonstrated dynamic transcript expression profiles across the developmental stages examined. The expression of thyroid receptor alpha (thraa) was observed in the brain, gastrointestinal tract, craniofacial tissues and pectoral fins, while thyroid receptor beta (thrb) expression occurred in the brain, otic vesicles, liver and lower jaw. The TH deiodinases (dio1, dio2 and dio3b) were expressed in the liver, pronephric ducts and brain and the patterns differed depending on life stage. Both dio1 and dio2 were also expressed in the intestinal bulb (96-120 hpf), and dio2 expression occurred also in the pituitary (48-120 hpf). Exposure of zebrafish embryo-larvae to T3 (30 and 100 µg L-1) for periods of 48, 96 or 120 hpf resulted in the up-regulation of thraa, thrb, dio3b, thyroid follicle synthesis proteins (pax8) and corticotropin-releasing hormone (crhb) and down-regulation of dio1, dio2, glucuronidation enzymes (ugt1ab) and thyroid stimulating hormone (tshb) (assessed via qRT-PCR) and responses differed across life stage and tissues. T3 induced thraa expression in the pineal gland, pectoral fins, brain, somites, gastrointestinal tract, craniofacial tissues, liver and pronephric ducts. T3 enhanced thrb expression in the brain, jaw cartilage and intestine, while thrb expression was suppressed in the liver. T3 exposure suppressed the transcript levels of dio1 and dio2 in the liver, brain, gastrointestinal tract and craniofacial tissues, while dio2 signalling was also suppressed in the pituitary gland. Dio3b expression was induced by T3 exposure in the jaw cartilage, pectoral fins and brain. The involvement of THs in the development of numerous body tissues and the responsiveness of these tissues to T3 in zebrafish highlights their potential vulnerability to exposure to environmental thyroid-disrupting chemicals.


Assuntos
Tri-Iodotironina/toxicidade , Poluentes Químicos da Água/toxicidade , Animais , Hormônio Liberador da Corticotropina , Hipotálamo/efeitos dos fármacos , Larva/efeitos dos fármacos , Hipófise/efeitos dos fármacos , Glândula Tireoide/efeitos dos fármacos , Hormônios Tireóideos/metabolismo , Tironinas/metabolismo , Tironinas/farmacologia , Tireotropina , Peixe-Zebra/fisiologia , Proteínas de Peixe-Zebra/genética
5.
Aquat Toxicol ; 225: 105524, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32610223

RESUMO

In the present research, the effects of exposure to a sublethal concentration of zinc (Zn) on metal and ion homeostasis, and the regulation and the localization of various Zn transporters (i.e., the Zrt-Irt Like Protein (ZIP) family of Zn transporters), were investigated in zebrafish (Danio rerio) during early development. Exposure to an elevated level of Zn [4 µM (high) vs. 0.25 µM (control)] from 0 day post-fertilization (dpf) resulted in a significant increase in the whole body content of Zn at 5 dpf. A transient decrease in the whole body calcium (Ca) level was observed in 3 dpf larvae exposed to high Zn. Similarly, whole body nickel (Ni) and copper (Cu) contents were also reduced in 3 dpf larvae exposed to high Zn. Importantly, the magnitude of reduction in whole body Ni and Cu contents following Zn exposure was markedly higher than that in Ca content, suggesting that internal Ni and Cu balance were likely more sensitive to Zn exposure in developing zebrafish. Exposure to high Zn altered the mRNA expression levels of specific zip transporters, with an increase in zip1 (at 3 dpf) and zip8 (at 5 dpf), and a decrease in zip4 (at 5 dpf). The expression levels of most zip transporters tended to decrease from 3 dpf to 5 dpf with the exception of zip4 and zip8. Results from in situ hybridization revealed that several zip transporters exhibited distinct spatial distribution (e.g., zip8 in the intestinal tract, zip14 in the pronephric tubules). Overall, our findings suggested that exposure to sublethal concentrations of Zn disrupts the homeostasis of essential metals during early development and that different ZIP transporters may play unique roles in regulating Zn homeostasis in various organs in developing zebrafish.


Assuntos
Proteínas de Transporte de Cátions/genética , Homeostase/efeitos dos fármacos , Poluentes Químicos da Água/toxicidade , Proteínas de Peixe-Zebra/genética , Peixe-Zebra , Zinco/toxicidade , Animais , Cálcio/metabolismo , Cobre/metabolismo , Relação Dose-Resposta a Droga , Larva/efeitos dos fármacos , Larva/metabolismo , Nível de Efeito Adverso não Observado , Poluentes Químicos da Água/metabolismo , Peixe-Zebra/fisiologia , Zinco/metabolismo
6.
Aquat Toxicol ; 226: 105555, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32645607

RESUMO

Fish strongly rely on olfaction as a variety of essential behaviors such as foraging and predator avoidance are mediated by the olfactory system. Cadmium (Cd) is known to impair olfaction and accumulate in the olfactory epithelium (OE) and bulb (OB) of fishes. In the present study, the acute toxicity of Cd on olfaction in zebrafish (Danio rerio) was characterized on the molecular and behavioral level. To this end, quantitative real-time PCR was performed in order to analyze the expression of selected genes in both the OE and OB. Moreover, the response of zebrafish to an alarm cue was investigated. Following 24 h of exposure to Cd, the expression of genes associated with olfactory sensory neurons was reduced in the OE. Furthermore, the antioxidant genes peroxiredoxin 1 (prdx1) and heme oxygenase 1 (hmox1), as well as the metallothionein 2 gene (mt2) were upregulated in the OE, whereas hmox1 and the stress-inducible heat shock protein 70 gene (hsp70) were upregulated in the OB upon exposure to Cd. Following stimulation with a conspecific skin extract, zebrafish displayed a considerable disruption of the antipredator behavior with increasing Cd concentration. Taken together, Cd impaired olfaction in zebrafish, thereby disrupting the antipredator response, which is crucial for the survival of individuals. Cellular stress followed by disruption of olfactory sensory neurons may have contributed to the observed behavioral deficits.


Assuntos
Comportamento Animal/efeitos dos fármacos , Cádmio/toxicidade , Regulação da Expressão Gênica/efeitos dos fármacos , Olfato/efeitos dos fármacos , Poluentes Químicos da Água/toxicidade , Peixe-Zebra , Animais , Antioxidantes/metabolismo , Proteínas de Choque Térmico HSP70/metabolismo , Metalotioneína/genética , Metalotioneína/metabolismo , Mucosa Olfatória/efeitos dos fármacos , Olfato/genética , Peixe-Zebra/genética , Peixe-Zebra/fisiologia
7.
Am J Physiol Regul Integr Comp Physiol ; 319(3): R329-R342, 2020 09 01.
Artigo em Inglês | MEDLINE | ID: mdl-32697653

RESUMO

Peripheral chemosensitivity in fishes is thought to be mediated by serotonin-enriched neuroepithelial cells (NECs) that are localized to the gills of adults and the integument of larvae. In adult zebrafish (Danio rerio), branchial NECs are presumed to mediate the cardiorespiratory reflexes associated with hypoxia or hypercapnia, whereas in larvae, there is indirect evidence linking cutaneous NECs to hypoxic hyperventilation and hypercapnic tachycardia. No study yet has examined the ventilatory response of larval zebrafish to hypercapnia, and regardless of developmental stage, the signaling pathways involved in CO2 sensing remain unclear. In the mouse, a background potassium channel (TASK-2) contributes to the sensitivity of chemoreceptor cells to CO2. Zebrafish possess two TASK-2 channel paralogs, TASK-2 and TASK-2b, encoded by kcnk5a and kcnk5b, respectively. The present study aimed to determine whether TASK-2 channels are expressed in NECs of larval zebrafish and whether they are involved in CO2 sensing. Using immunohistochemical approaches, TASK-2 protein was observed on the surface of NECs in larvae. Exposure of larvae to hypercapnia caused cardiac and breathing frequencies to increase, and these responses were blunted in fish experiencing TASK-2 and/or TASK-2b knockdown. The results of these experiments suggest that TASK-2 channels are involved in CO2 sensing by NECs and contribute to the initiation of reflex cardiorespiratory responses during exposure of larvae to hypercapnia.


Assuntos
Dióxido de Carbono/metabolismo , Hipercapnia/metabolismo , Hipóxia/metabolismo , Células Neuroepiteliais/metabolismo , Canais de Potássio de Domínios Poros em Tandem/metabolismo , Proteínas de Peixe-Zebra/metabolismo , Animais , Células Quimiorreceptoras/metabolismo , Brânquias/metabolismo , Hiperventilação/metabolismo , Células Neuroepiteliais/citologia , Oxigênio/metabolismo , Peixe-Zebra/fisiologia
8.
Proc Natl Acad Sci U S A ; 117(29): 17330-17337, 2020 07 21.
Artigo em Inglês | MEDLINE | ID: mdl-32632015

RESUMO

Purkinje cells, the principal neurons of cerebellar computations, are believed to comprise a uniform neuronal population of cells, each with similar functional properties. Here, we show an undiscovered heterogeneity of adult zebrafish Purkinje cells, revealing the existence of anatomically and functionally distinct cell types. Dual patch-clamp recordings showed that the cerebellar circuit contains all Purkinje cell types that cross-communicate extensively using chemical and electrical synapses. Further activation of spinal central pattern generators (CPGs) revealed unique phase-locked activity from each Purkinje cell type during the locomotor cycle. Thus, we show intricately organized Purkinje cell networks in the adult zebrafish cerebellum that encode the locomotion rhythm differentially, and we suggest that these organizational properties may also apply to other cerebellar functions.


Assuntos
Locomoção/fisiologia , Células de Purkinje/fisiologia , Peixe-Zebra/fisiologia , Potenciais de Ação , Animais , Comportamento Animal , Encéfalo , Geradores de Padrão Central/fisiologia , Cerebelo/fisiologia , Análise por Conglomerados , Fenômenos Eletrofisiológicos , Feminino , Masculino , Modelos Animais , Medula Espinal
9.
PLoS Biol ; 18(7): e3000462, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-32697779

RESUMO

Most fish swim with body undulations that result from fluid-structure interactions between the fish's internal tissues and the surrounding water. Gaining insight into these complex fluid-structure interactions is essential to understand how fish swim. To this end, we developed a dedicated experimental-numerical inverse dynamics approach to calculate the lateral bending moment distributions for a large-amplitude undulatory swimmer that moves freely in three-dimensional space. We combined automated motion tracking from multiple synchronised high-speed video sequences, computation of fluid dynamic stresses on the swimmer's body from computational fluid dynamics, and bending moment calculations using these stresses as input for a novel beam model of the body. The bending moment, which represent the system's net actuation, varies over time and along the fish's central axis due to muscle actions, passive tissues, inertia, and fluid dynamics. Our three-dimensional analysis of 113 swimming events of zebrafish larvae ranging in age from 3 to 12 days after fertilisation shows that these bending moment patterns are not only relatively simple but also strikingly similar throughout early development and from fast starts to periodic swimming. This suggests that fish larvae may produce and adjust swimming movements relatively simply, yet effectively, while restructuring their neuromuscular control system throughout their rapid development.


Assuntos
Análise Numérica Assistida por Computador , Natação/fisiologia , Peixe-Zebra/fisiologia , Animais , Fenômenos Biomecânicos , Fertilização , Larva/fisiologia , Modelos Biológicos , Movimento (Física) , Cauda
10.
Chemosphere ; 260: 127609, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-32693259

RESUMO

The environmental contaminant 3,3'-dichlorobiphenyl (PCB-11) is widely detected in environmental samples, and this parent compound along with its metabolites 4-OH-PCB-11 and 4-PCB-11-Sulfate are detected in human serum. Our previous research in zebrafish (Danio rerio) embryos shows exposure to 20 µM PCB-11 inhibits Cyp1a enzyme activity and perturbs lipid metabolism pathways. In this study, wildtype AB embryos underwent acute exposures from 1 to 4 days post fertilization (dpf) to 0.002-20 µM 4-OH-PCB-11 or 0.2-20 µM 4-PCB-11-Sulfate, with and without co-exposures to 100 µg/L benzo[a]pyrene (B[a]P) or 5 nM 3,3',4,4',5-pentachlorobiphenyl (PCB-126), and were assessed for in vivo EROD activity and morphometrics. Chronic exposures from 1 to 15 dpf to assess lipid accumulation using Oil-Red-O staining were also conducted with 0.2 µM parent or metabolite compounds, alongside a co-exposure experiment of 0.002-0.2 µM 4-PCB-11-Sulfate and 10 µg/L B[a]P. For acute experiments, 2 and 20 µM 4-OH-PCB-11 was lethal but no Cyp1a or morphological effects were observed at lower concentrations; 20 µM 4-PCB-11-Sulfate significantly lowered the Cyp1a activity of B[a]P and PCB-126 but did not alter morphological development. For chronic experiments, 0.2 µM 4-PCB-11-Sulfate significantly increased lipid accumulation 30% in single exposures and 44% in co-exposures with B[a]P. Further long-term studies would better elucidate the effects of this contaminant, particularly in the context of environmentally-relevant mixtures.


Assuntos
Bifenilos Policlorados/toxicidade , Peixe-Zebra/fisiologia , Animais , Benzo(a)pireno/metabolismo , Citocromo P-450 CYP1A1/metabolismo , Embrião não Mamífero/metabolismo , Larva/metabolismo , Lipídeos , Fígado/metabolismo , Bifenilos Policlorados/metabolismo , Sulfatos/metabolismo , Peixe-Zebra/metabolismo
11.
PLoS One ; 15(6): e0229549, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32497078

RESUMO

Dysfunctions in the GABAergic system lead to various pathological conditions and impaired inhibitory function is one of the causes behind neuropathies characterized by neuronal hyper excitability. The Dlx homeobox genes are involved in the development of nervous system, neural crest, branchial arches and developing appendages. Dlx genes also take part in neuronal migration and differentiation during development, more precisely, in the migration and differentiation of GABAergic neurons. Functional analysis of dlx genes has mainly been carried out in developing zebrafish embryos and larvae, however information regarding the expression and roles of these genes in the adult zebrafish brain is still lacking. The extensive neurogenesis that takes place in the adult zebrafish brain, makes them a good model for the visualization of mechanisms involving dlx genes during adulthood in physiological conditions and during regeneration of the nervous system. We have identified the adult brain regions where transcripts of dlx1a, dlx2a, dlx5a and dlx6a genes are normally found and have confirmed that within telencephalic domains, there is high overlapping expression of the four dlx paralogs with a marker for GABAergic neurons. Co-localization analyses carried with the Tg(dlx6a-1.4kbdlx5a/dlx6a:GFP) reporter line have also shown that in some areas of the diencephalon, cells expressing the dlx5a/6a bigene may have a neural stem cell identity. Furthermore, investigations in a response to stab wound lesions, have demonstrated a possible participation of the dlx5a/6a bigene, most likely of dlx5a, during regeneration of the adult zebrafish brain. These observations suggest a possible participation of dlx-expressing cells during brain regeneration in adult zebrafish and also provide information on the role of dlx genes under normal physiological conditions in adults.


Assuntos
Encéfalo/fisiologia , Regulação da Expressão Gênica , Proteínas de Homeodomínio/genética , Proteínas de Homeodomínio/metabolismo , Regeneração , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismo , Peixe-Zebra/genética , Peixe-Zebra/fisiologia , Animais , Encéfalo/citologia , Encéfalo/metabolismo , Células-Tronco Neurais/metabolismo
12.
Ecotoxicol Environ Saf ; 202: 110876, 2020 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-32563953

RESUMO

This study investigated the acute in vitro effect of low-concentration bisphenol A (BPA) on calcium (45Ca2+) influx in zebrafish (Danio rerio) testis and examined whether intracellular Ca2+ was involved in the effects of BPA on testicular toxicity. In vitro studies on 45Ca2+ influx were performed in the testes after incubation with BPA for 30 min. Inhibitors were added 15 min before the addition of 45Ca2+ and BPA to testes to study the mechanism of action of BPA. The involvement of intracellular calcium from stores on lactate dehydrogenase (LDH) release and on triacylglycerol (TAG) content were carried out after in vitro incubation of testes with BPA for 1 h. Furthermore, gamma-glutamyl transpeptidase (GGT) and aspartate aminotransferase (AST) activities were analyzed in the liver at 1 h after in vitro BPA incubation of D. rerio. Our data show that the acute in vitro treatment of D. rerio testes with BPA at very low concentration activates plasma membrane ionic channels, such as voltage-dependent calcium channels and calcium-dependent chloride channels, and protein kinase C (PKC), which stimulates Ca2+ influx. In addition, BPA increased cytosolic Ca2+ by activating inositol triphosphate receptor (IP3R) and inhibiting sarco/endoplasmic reticulum calcium ATPase (SERCA) at the endoplasmic reticulum, contributing to intracellular Ca2+ overload. The protein kinases, PKC, MEK 1/2 and PI3K, are involved in the mechanism of action of BPA, which may indicate a crosstalk between the non-genomic initiation effects mediated by PLC/PKC/IP3R signaling and genomic responses of BPA mediated by the estrogen receptor (ESR). In vitro exposure to a higher concentration of BPA caused cell damage and plasma membrane injury with increased LDH release and TAG content; both effects were dependent on intracellular Ca2+ and mediated by IP3R. Furthermore, BPA potentially induced liver damage, as demonstrated by increased GGT activity. In conclusion, in vitro effect of BPA in a low concentration triggers cytosolic Ca2+ overload and activates downstream protein kinases pointing to a crosstalk between its non-genomic and genomic effects of BPA mediated by ESR. Moreover, in vitro exposure to a higher concentration of BPA caused intracellular Ca2+-dependent testicular cell damage and plasma membrane injury. This acute toxicity was reinforced by increased testicular LDH release and GGT activity in the liver.


Assuntos
Compostos Benzidrílicos/toxicidade , Cálcio/metabolismo , Fenóis/toxicidade , Testículo/efeitos dos fármacos , Poluentes Químicos da Água/toxicidade , Peixe-Zebra/fisiologia , Animais , Membrana Celular/metabolismo , Citosol/metabolismo , Retículo Endoplasmático/metabolismo , Receptores de Inositol 1,4,5-Trifosfato/antagonistas & inibidores , Receptores de Inositol 1,4,5-Trifosfato/metabolismo , Canais Iônicos , Masculino , Proteína Quinase C/metabolismo , Proteína Quinase C/farmacologia , Transdução de Sinais/efeitos dos fármacos , Testículo/metabolismo , Peixe-Zebra/metabolismo
13.
Chemosphere ; 257: 127177, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32480090

RESUMO

Zinc pyrithione (ZPT) is an extensively used microbicidal agent and its toxicity to multiple organs has been gradually recognized. However, details of the mechanism of ZPT toxicity are lacking and profile studies at metabolic level are still greatly limited. In this work we investigated the effects of ZPT on metabolic pathways of zebrafish liver after twenty-one days of exposure. Our integrated approach was underpinned by gas chromatography coupled with mass spectroscopy (GC-MS) and liver function analysis. Metabolomic profiles were generated from the livers of ZPT-treated zebrafish and 172 significantly altered metabolite peaks were detected. As a result, ZPT caused altered perturbation of metabolic pathways in male and female zebrafish liver. Moreover, ZPT induced the liver injury with the changes of the metabolites 2,4-diaminobutyric acid (2,4-DABA) with significant distinction between male and female zebrafish. ZPT caused gender-differentiated liver metabolic changes associated with the disruption of glycogenolysis and glycolysis metabolism, purine and pyrimidine metabolism, oxidative phosphorylation, arginine biosynthesis, and amino acid metabolism. Conclusively, exposure of ZPT may result in gender-differentiated metabolic abnormalities of adult zebrafish with induced hepatotoxicity.


Assuntos
Compostos Organometálicos/toxicidade , Piridinas/toxicidade , Poluentes Químicos da Água/toxicidade , Peixe-Zebra/fisiologia , Animais , Diferenciação Celular , Doença Hepática Induzida por Substâncias e Drogas/metabolismo , Feminino , Cromatografia Gasosa-Espectrometria de Massas , Glicólise , Fígado/metabolismo , Masculino
14.
Chemosphere ; 257: 127170, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32497837

RESUMO

Ammonia (including NH3 and NH4+) is a major pollutant of freshwater environments. However, the toxic effects of ammonia on the early stages of fish are not fully understood, and little is known about the effects on the sensory system. In this study, we hypothesized that ammonia exposure can cause adverse effects on embryonic development and impair the lateral line system of fish. Zebrafish embryos were exposed to high-ammonia water (10, 15, 20, 25, and 30 mM NH4Cl; pH 7.0) for 96 h (0-96 h post-fertilization). The body length, heart rate, and otic vesicle size had significantly decreased with ≥15 mM NH4Cl, while the number and function of lateral-line hair cells had decreased with ≥10 mM NH4Cl. The mechanoelectrical transduction (MET) channel-mediated Ca2+ influx was measured with a scanning ion-selective microelectrode technique to reveal the function of hair cells. We found that NH4+ (≥5 mM NH4Cl) entered hair cells and suppressed the Ca2+ influx of hair cells. Neomycin and La3+ (MET channel blockers) suppressed NH4+ influx, suggesting that NH4+ enters hair cells via MET channels in hair bundles. In conclusion, this study showed that ammonia exposure (≥10 mM NH4Cl) can cause adverse effects in zebrafish embryos, and lateral-line hair cells are sensitive to ammonia exposure.


Assuntos
Amônia/metabolismo , Sistema da Linha Lateral/efeitos dos fármacos , Amônia/toxicidade , Animais , Desenvolvimento Embrionário , Células Ciliadas Auditivas/efeitos dos fármacos , Mecanotransdução Celular/efeitos dos fármacos , Mecanotransdução Celular/fisiologia , Peixe-Zebra/embriologia , Peixe-Zebra/fisiologia
15.
Chemosphere ; 259: 127456, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32593829

RESUMO

Secondary microplastics (MP) produced by fragmentation of plastic in the environment or as a result of human activities can easily be taken up by organisms. The harmful effects of MP depend on e.g., the type, dimensions, sorption capacity and concentration of MP. In this study the ingestion of virgin irregularly-shaped polyamide microplastics (PA-MP; up to180 µm) by two different species was evaluated: 3rd - 4th instar larvae of midge Chironomus riparius and adult fish Danio rerio. More specifically, in the case of C. riparius larvae their feeding strategy, i.e. the ability to differentiate between food and non-food material (PA-MP) and the impact of pseudo-satiation by PA-MP on larval growth, development and emergence was evaluated. Two feeding regimes (with and without food supply) and two PA-MP concentrations (100 mg kg-1 and 1000 mg kg-1) were applied. Fish were exposed to two PA-MP concentrations (30 and 330 mg L-1) for 48 h followed by 48 h of depuration. The fish were fed during both periods. Both, chironomid larvae and adult zebrafish actively ingested PA-MP. Remarkably more PA-MP was ingested when larvae were not fed during the exposure to PA-MP. In the case of fish, the ingested particles were effectively evacuated from the gastrointestinal tract. Even the highest PA-MP concentrations did not cause obvious harmful effects to either species. The obtained data are informative for risk evaluation of PA-MP as polyamide is registered in the database of the European Chemicals Agency (ECHA) in the framework of the EU's REACH (Registration, Evaluation, Authorization & Restriction of Chemicals) regulation.


Assuntos
Chironomidae/fisiologia , Microplásticos/análise , Poluentes Químicos da Água/análise , Peixe-Zebra/fisiologia , Animais , Chironomidae/efeitos dos fármacos , Ingestão de Alimentos , Humanos , Larva/efeitos dos fármacos , Nylons , Plásticos/farmacologia
16.
J Vis Exp ; (159)2020 05 20.
Artigo em Inglês | MEDLINE | ID: mdl-32510477

RESUMO

Hair cells are mechanosensory cells that mediate the sense of hearing. These cells do not regenerate after damage in humans, but they are naturally replenished in non-mammalian vertebrates such as zebrafish. The zebrafish lateral line system is a useful model for characterizing sensory hair cell regeneration. The lateral line is comprised of hair cell-containing organs called neuromasts, which are linked together by a string of interneuromast cells (INMCs). INMCs act as progenitor cells that give rise to new neuromasts during development. INMCs can repair gaps in the lateral line system created by cell death. A method is described here for selective INMC ablation using a conventional laser-scanning confocal microscope and transgenic fish that express green fluorescent protein in INMCs. Time-lapse microscopy is then used to monitor INMC regeneration and determine the rate of gap closure. This represents an accessible protocol for cell ablation that does not require specialized equipment, such as a high-powered pulsed ultraviolet laser. The ablation protocol may serve broader interests, as it could be useful for the ablation of additional cell types, employing a tool set that is already available to many users. This technique will further enable the characterization of INMC regeneration under different conditions and from different genetic backgrounds, which will advance the understanding of sensory progenitor cell regeneration.


Assuntos
Bioensaio/métodos , Interneurônios/citologia , Terapia a Laser , Microscopia Confocal , Regeneração/fisiologia , Peixe-Zebra/fisiologia , Anestesia , Animais , Animais Geneticamente Modificados , Corpo Celular/metabolismo , Morte Celular , Fluorescência , Proteínas de Fluorescência Verde/metabolismo , Processamento de Imagem Assistida por Computador , Larva/citologia , Modelos Logísticos , Peixe-Zebra/genética
17.
Proc Biol Sci ; 287(1927): 20200798, 2020 05 27.
Artigo em Inglês | MEDLINE | ID: mdl-32453991

RESUMO

The coordination of the hypoxic response is attributed, in part, to hypoxia-inducible factor 1α (Hif-1α), a regulator of hypoxia-induced transcription. After the teleost-specific genome duplication, most teleost fishes lost the duplicate copy of Hif-1α, except species in the cyprinid lineage that retained both paralogues of Hif-1α (Hif1aa and Hif1ab). Little is known about the contribution of Hif-1α, and specifically of each paralogue, to hypoxia tolerance. Here, we examined hypoxia tolerance in wild-type (Hif1aa+/+ab+/+) and Hif-1α knockout lines (Hif1aa-/-; Hif1ab-/-; Hif1aa-/-ab-/-) of zebrafish (Danio rerio). Critical O2 tension (Pcrit; the partial pressure of oxygen (PO2) at which O2 consumption can no longer be maintained) and time to loss of equilibrium (LOE), two indices of hypoxia tolerance, were assessed in larvae and adults. Knockout of both paralogues significantly increased Pcrit (decreased hypoxia tolerance) in larval fish. Prior exposure of larvae to hypoxia decreased Pcrit in wild-type fish, an effect mediated by the Hif1aa paralogue. In adults, individuals with a knockout of either paralogue exhibited significantly decreased time to LOE but no difference in Pcrit. Together, these results demonstrate that in zebrafish, tolerance to hypoxia and improved hypoxia tolerance after pre-exposure to hypoxia (pre-conditioning) are mediated, at least in part, by Hif-1α.


Assuntos
Subunidade alfa do Fator 1 Induzível por Hipóxia/metabolismo , Peixe-Zebra/fisiologia , Animais , Hipóxia
18.
Chemosphere ; 256: 127038, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32470728

RESUMO

Baicalein is a flavonoid that is widely found in plants. Studies have shown that baicalein has anti-inflammatory, anti-cancer, and liver-protective effects. However, the effects of baicalein on TAA-induced toxicity and the underlying molecular mechanisms in zebrafish larvae are still unknown. Here, we investigated the effects of baicalein on liver development and its anti-inflammatory effects in zebrafish larvae. The results showed that baicalein has significant anti-embryonic developmental toxicity and significant antioxidant and anti-inflammatory capabilities in TAA-induced zebrafish larvae and promotes liver development and cell proliferation, reduces the expression of apoptotic proteins, and induces the expression of anti-apoptotic proteins. At the molecular level of TAA-treated zebrafish larvae, there was a decrease in the relative expression levels of mRNAs of three subfamilies, P38, ERK1, and ERK2, of the MAPK-signaling pathway and of the products of peroxisome proliferator-activated receptor (PPAR)α. Compared with TAA-treated zebrafish larvae, zebrafish larvae treated with baicalein showed an increase in the relative expression levels of P38, ERK1, and ERK2 mRNAs and the downstream products of PPARα. When MAPK signal inhibitor (SB203580) was added, it was found that liver development was inhibited and baicalin had no protective effect on TAA induced hepatotoxicity in zebrafish larvae. The results showed baicalein can protect the zebrafish larvae against toxicity induced by TAA through MAPK signal pathway. Several molecular mechanisms discovered in this study may help in the development of new drugs.


Assuntos
Flavanonas/toxicidade , Tioacetamida/toxicidade , Peixe-Zebra/fisiologia , Animais , Anti-Inflamatórios/metabolismo , Antioxidantes/metabolismo , Flavonoides , Larva/efeitos dos fármacos , Fígado/efeitos dos fármacos , Sistema de Sinalização das MAP Quinases/efeitos dos fármacos , PPAR alfa , Substâncias Protetoras/metabolismo , Transdução de Sinais/efeitos dos fármacos
19.
Chemosphere ; 255: 126934, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32387730

RESUMO

Environmental factors, such as photoperiod and temperature were the main limiting factors for the survival of organisms in the nature environment. Changes in environmental factors are well predicted but determining their effects on organisms are challenging hot topic in the field of eco-toxicology. Thus, technology based eco-toxicity assessment was focused worldwide. In this research, the effects of different temperatures (15 °C, 22 °C, 30 °C, 32 °C, and 35 °C) and photoperiods (dark and light periods) on the continuous behavior responses of Zebrafish (Danio rerio) were investigated using an online monitoring system (OMS). We designed a new fish chamber with sensors to measure the behavior responses of zebrafish under different conditions. Data obtained from the OMS could be assessed for factors such as difference in swimming behavior, circadian rhythm, and avoidance behavior using latest software (MATLAB). The observed behavior anomalies on zebrafish under different temperatures and continuous photoperiods were statically significant (p < 0.05). We conclude that the new designed fish chamber (behavior sensors) is good in sensing behavioral responses of zebrafish under different conditions. The fish behavior strength could be a potential biomarker to assess the effects of environmental factors. The present study would be a basic platform for assessing the effects of different stressors simultaneously on swimming behavior of zebrafish.


Assuntos
Comportamento Animal/efeitos dos fármacos , Monitoramento Ambiental , Poluentes Químicos da Água/toxicidade , Animais , Ritmo Circadiano , Fotoperíodo , Natação , Peixe-Zebra/fisiologia
20.
PLoS One ; 15(5): e0232457, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32401822

RESUMO

Because of its powerful genetics, the adult zebrafish has been increasingly used for studying cardiovascular diseases. Considering its heart rate of ~100 beats per minute at ambient temperature, which is very close to human, we assessed the use of this vertebrate animal for modeling heart rhythm disorders such as sinus arrest (SA) and sick sinus syndrome (SSS). We firstly optimized a protocol to measure electrocardiogram in adult zebrafish. We determined the location of the probes, implemented an open-chest microsurgery procedure, measured the effects of temperature, and determined appropriate anesthesia dose and time. We then proposed an PP interval of more than 1.5 seconds as an arbitrary criterion to define an SA episode in an adult fish at ambient temperature, based on comparison between the current definition of an SA episode in humans and our studies of candidate SA episodes in aged wild-type fish and Tg(SCN5A-D1275N) fish (a fish model for inherited SSS). With this criterion, a subpopulation of about 5% wild-type fish can be considered to have SA episodes, and this percentage significantly increases to about 25% in 3-year-old fish. In response to atropine, this subpopulation has both common SSS phenotypic traits that are shared with the Tg(SCN5A-D1275N) model, such as bradycardia; and unique SSS phenotypic traits, such as increased QRS/P ratio and chronotropic incompetence. In summary, this study defined baseline SA and SSS in adult zebrafish and underscored use of the zebrafish as an alternative model to study aging-associated SSS.


Assuntos
Envelhecimento/genética , Envelhecimento/fisiologia , Síndrome do Nó Sinusal/etiologia , Parada Sinusal Cardíaca/etiologia , Peixe-Zebra/genética , Peixe-Zebra/fisiologia , Animais , Animais Geneticamente Modificados , Modelos Animais de Doenças , Eletrocardiografia , Humanos , Camundongos , Modelos Cardiovasculares , Mutação de Sentido Incorreto , Canal de Sódio Disparado por Voltagem NAV1.5/genética , Síndrome do Nó Sinusal/genética , Síndrome do Nó Sinusal/fisiopatologia , Parada Sinusal Cardíaca/genética , Parada Sinusal Cardíaca/fisiopatologia , Especificidade da Espécie , Proteínas de Peixe-Zebra/genética
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA