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1.
Ecotoxicol Environ Saf ; 196: 110560, 2020 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-32247955

RESUMO

Lithobates catesbeianus tadpoles were exposed to 1 µg L-1 of zinc (Zn), copper (Cu) and cadmium (Cd) alone or combined (1:1 and 1:1:1) for 2 and 16 days. Results showed a significant increase in the superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx) and glutathione S-transferase (GST) activities in the liver, kidney and muscle (except for GPx) in the groups exposed to metal either alone or co-exposed after 2 days compared to the control. After 16 days, SOD, CAT and GST activities decreased significantly in the liver and kidney and GPx activity increased in the liver. Reduced glutathione (GSH) increased in the liver and kidney following combined exposure and decreased after 2 days of metal exposure in the muscle. There were significant increases in lipid hydroperoxide (LPO) levels in the liver, kidney and muscle (2 and 16 days), with the highest levels after metal co-exposure. Cholinesterase (ChE) activity increased significantly in the brain after 2 days of exposure but decreased in the brain (16 days) and muscle (2 days) after exposure to metals, alone and combined. The current study highlighted that the antioxidant system of L. catesbeianus was sensitive to metals and specially to the co-exposure of the three metals, despite presenting differences in the response among tissues. In addition, tadpoles were sensitive at both periods of exposure, but in different modes with stress response (activation, up-regulation) at 2 days and oppression (down-regulation) at 16 days.


Assuntos
Antioxidantes/metabolismo , Encéfalo/efeitos dos fármacos , Exposição Ambiental/análise , Larva/efeitos dos fármacos , Metais Pesados/toxicidade , Estresse Oxidativo/efeitos dos fármacos , Animais , Biomarcadores/metabolismo , Encéfalo/metabolismo , Cádmio/toxicidade , Cobre/toxicidade , Rim/efeitos dos fármacos , Rim/metabolismo , Larva/metabolismo , Fígado/efeitos dos fármacos , Fígado/metabolismo , Metais Pesados/metabolismo , Rana catesbeiana , Zinco/toxicidade
2.
Ecotoxicology ; 29(3): 314-326, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-32107698

RESUMO

Anthropogenic activities promote changes in community structure and decrease the species abundance of amphibians. The aim of this study was to assess potential alterations in the antioxidant system and cholinesterase activity, histopathological and oxidative damage in Lithobates catesbeianus tadpoles exposed to water from the Cascavel River, in Southern Brazil. Water samples (140 L each) were collected from the headwater, urban and rural areas of the river. Tadpoles were acclimated for seven days. After acclimatization tadpoles were reared in water from the river, except for the control aquarium. After seven days, a portion of the liver was removed and prepared for cholinesterase (ChE), superoxide dismutase (SOD), catalase (CAT) and lipid peroxidation (LPO) analysis; another part of the tissue was prepared for histological examination. An elevation of CAT activity was observed for water from both urban and rural environments. A decrease in LPO reaction was detected, mainly among the tadpoles exposed to water from the rural area. These alternations can cause delay the metamorphosis and lead to metabolic dysfunction, interfering in survival capacity and diminishing, not only individual fitness, but that of the whole population.


Assuntos
Antioxidantes/metabolismo , Colinesterases/metabolismo , Rana catesbeiana/fisiologia , Poluentes Químicos da Água/toxicidade , Animais , Brasil , Larva/fisiologia , Peroxidação de Lipídeos , Metamorfose Biológica/efeitos dos fármacos , Rios , Poluentes Químicos da Água/metabolismo
3.
Proc Natl Acad Sci U S A ; 117(3): 1772-1778, 2020 01 21.
Artigo em Inglês | MEDLINE | ID: mdl-31879350

RESUMO

Fluid fills intracellular, extracellular, and capillary spaces within muscle. During normal physiological activity, intramuscular fluid pressures develop as muscle exerts a portion of its developed force internally. These pressures, typically ranging between 10 and 250 mmHg, are rarely considered in mechanical models of muscle but have the potential to affect performance by influencing force and work produced during contraction. Here, we test a model of muscle structure in which intramuscular pressure directly influences contractile force. Using a pneumatic cuff, we pressurize muscle midcontraction at 260 mmHg and report the effect on isometric force. Pressurization reduced isometric force at short muscle lengths (e.g., -11.87% of P0 at 0.9 L0), increased force at long lengths (e.g., +3.08% of P0 at 1.25 L0), but had no effect at intermediate muscle lengths ∼1.1-1.15 L0 This variable response to pressurization was qualitatively mimicked by simple physical models of muscle morphology that displayed negative, positive, or neutral responses to pressurization depending on the orientation of reinforcing fibers representing extracellular matrix collagen. These findings show that pressurization can have immediate, significant effects on muscle contractile force and suggest that forces transmitted to the extracellular matrix via pressurized fluid may be important, but largely unacknowledged, determinants of muscle performance in vivo.


Assuntos
Fenômenos Biomecânicos , Líquidos Corporais/fisiologia , Pressão Hidrostática , Contração Muscular/fisiologia , Animais , Colágeno , Matriz Extracelular , Músculos Isquiossurais/fisiologia , Contração Isométrica , Modelos Biológicos , Músculo Esquelético/fisiologia , Rana catesbeiana
4.
Int J Mol Sci ; 20(23)2019 Nov 30.
Artigo em Inglês | MEDLINE | ID: mdl-31801239

RESUMO

Many biological processes are triggered or driven by mechanical forces in the cytoskeletal network, but these transducing forces have rarely been assessed. Striated muscle, with its well-organized structure provides an opportunity to assess intracellular forces using small-angle X-ray fiber diffraction. We present a new methodology using Monte Carlo simulations of muscle contraction in an explicit 3D sarcomere lattice to predict the fiber deformations and length changes along thin filaments during contraction. Comparison of predicted diffraction patterns to experimental meridional X-ray reflection profiles allows assessment of the stepwise changes in intermonomer spacings and forces in the myofilaments within living muscle cells. These changes along the filament length reflect the effect of forces from randomly attached crossbridges. This approach enables correlation of the molecular events, such as the current number of attached crossbridges and the distributions of crossbridge forces to macroscopic measurements of force and length changes during muscle contraction. In addition, assessments of fluctuations in local forces in the myofilaments may reveal how variations in the filament forces acting on signaling proteins in the sarcomere M-bands and Z-discs modulate gene expression, protein synthesis and degradation, and as well to mechanisms of adaptation of muscle in response to changes in mechanical loading.


Assuntos
Citoesqueleto de Actina/fisiologia , Actinas/fisiologia , Contração Isométrica/fisiologia , Músculo Estriado/fisiologia , Miosinas/fisiologia , Sarcômeros/fisiologia , Citoesqueleto de Actina/ultraestrutura , Actinas/ultraestrutura , Animais , Simulação por Computador , Conectina/fisiologia , Conectina/ultraestrutura , Modelos Biológicos , Método de Monte Carlo , Músculo Estriado/diagnóstico por imagem , Miosinas/ultraestrutura , Rana catesbeiana/fisiologia , Sarcômeros/ultraestrutura , Espalhamento a Baixo Ângulo , Técnicas de Cultura de Tecidos , Difração de Raios X
5.
Genes Genet Syst ; 94(5): 207-217, 2019 Dec 10.
Artigo em Inglês | MEDLINE | ID: mdl-31748465

RESUMO

The cytosolic sulfotransferase 1 (SULT1) proteins are a family of highly divergent proteins that show variable expansion in different species during vertebrate evolution. To clarify the evolutionary origin of the mammalian lineage of the SULT1 family, we compiled Xenopus laevis and X. tropicalis SULT1 (XSULT1) sequences from public databases. The XSULT1 family was found to comprise at least six subfamilies, which corresponded in part to five mammalian SULT1 subfamilies but only poorly to zebrafish SULT1 subfamilies. SULT1C was most highly expanded, and could be divided into at least five subfamilies. A cDNA for X. laevis SULT1B (XlSULT1B.S), a homolog of mammalian SULT1B1, was cloned and its recombinant protein was expressed in a bacterial system. XlSULT1B.S, unlike mammalian SULT1B1, was found to be a monomeric protein of ~34 kDa, and displayed sulfonating activity toward 2-naphthol and p-nitrophenol (pNP). However, we could not detect such sulfonating activity toward any endogenous compounds including thyroid hormones, steroid hormones and dopamine, despite the fact that X. laevis and Rana catesbeiana liver cytosols contained sulfonating activity toward most of these endogenous compounds. At optimum pH (6.4), the Michaelis-Menten constant (Km) for pNP was two orders of magnitude greater in XlSULT1B.S (1.04 mM) than in the cytosol preparations (8-15 µM). Our results indicate that Xenopus possesses a prototype of the mammalian SULT1 family, and that XlSULT1B.S showed overall similarities in primary sequence to, and significant differences in molecular and enzymatic properties from, mammalian SULT1B1.


Assuntos
Sulfotransferases/metabolismo , Xenopus laevis/metabolismo , Animais , Clonagem Molecular , Evolução Molecular , Feminino , Humanos , Fígado/enzimologia , Masculino , Filogenia , Rana catesbeiana , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo , Análise de Sequência de Proteína , Especificidade da Espécie , Sulfotransferases/genética , Sulfotransferases/isolamento & purificação , Xenopus
6.
PLoS One ; 14(9): e0223020, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31560707

RESUMO

The fungal pathogen Batrachochytrium dendrobatidis (Bd) is the causative agent of chytridiomycosis and has been a key driver in the catastrophic decline of amphibians globally. While many strategies have been proposed to mitigate Bd outbreaks, few have been successful. In recent years, the use of probiotic formulations that protect an amphibian host by killing or inhibiting Bd have shown promise as an effective chytridiomycosis control strategy. The North American bullfrog (Lithobates catesbeianus) is a common carrier of Bd and harbours a diverse skin microbiota that includes lactic acid bacteria (LAB), a microbial group containing species classified as safe and conferring host benefits. We investigated beneficial/probiotic properties: anti-Bd activity, and adhesion and colonisation characteristics (hydrophobicity, biofilm formation and exopolysaccharide-EPS production) in two confirmed LAB (cLAB-Enterococcus gallinarum CRL 1826, Lactococcus garvieae CRL 1828) and 60 presumptive LAB (pLAB) [together named as LABs] isolated from bullfrog skin.We challenged LABs against eight genetically diverse Bd isolates and found that 32% of the LABs inhibited at least one Bd isolate with varying rates of inhibition. Thus, we established a score of sensitivity from highest (BdGPL AVS7) to lowest (BdGPL C2A) for the studied Bd isolates. We further reveal key factors underlying host adhesion and colonisation of LABs. Specifically, 90.3% of LABs exhibited hydrophilic properties that may promote adhesion to the cutaneous mucus, with the remaining isolates (9.7%) being hydrophobic in nature with a surface polarity compatible with colonisation of acidic, basic or both substrate types. We also found that 59.7% of LABs showed EPS synthesis and 66.1% produced biofilm at different levels: 21% weak, 29% moderate, and 16.1% strong. Together all these properties enhance colonisation of the host surface (mucus or epithelial cells) and may confer protective benefits against Bd through competitive exclusion. Correspondence analysis indicated that biofilm synthesis was LABs specific with high aggregating bacteria correlating with strong biofilm producers, and EPS producers being correlated to negative biofilm producing LABs. We performed Random Amplified Polymorphic DNA (RAPD)-PCR analysis and demonstrated a higher degree of genetic diversity among rod-shaped pLAB than cocci. Based on the LAB genetic analysis and specific probiotic selection criteria that involve beneficial properties, we sequenced 16 pLAB which were identified as Pediococcus pentosaceus, Enterococcus thailandicus, Lactobacillus pentosus/L. plantarum, L. brevis, and L. curvatus. Compatibility assays performed with cLAB and the 16 species described above indicate that all tested LAB can be included in a mixed probiotic formula. Based on our analyses, we suggest that E. gallinarum CRL 1826, L. garvieae CRL 1828, and P. pentosaceus 15 and 18B represent optimal probiotic candidates for Bd control and mitigation.


Assuntos
Quitridiomicetos/patogenicidade , Lactobacillales/imunologia , Microbiota/imunologia , Micoses/veterinária , Probióticos/isolamento & purificação , Rana catesbeiana/microbiologia , Animais , Quitridiomicetos/isolamento & purificação , DNA Bacteriano , Lactobacillales/genética , Lactobacillales/isolamento & purificação , Micoses/imunologia , Micoses/microbiologia , Rana catesbeiana/imunologia , Técnica de Amplificação ao Acaso de DNA Polimórfico , Pele/imunologia , Pele/microbiologia
7.
J Therm Biol ; 84: 488-495, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31466790

RESUMO

Severe environmental stressors such as low temperatures can affect gene expression by changing epigenetic states. American bullfrog (Rana catesbeiana) can overwinter as tadpoles, which can be active even in winter. However, the molecular mechanisms of epigenetic controls by which the tadpoles acclimate to low temperature are still unclear. In this study, we aimed to clarify the molecular mechanisms of global and gene-specific epigenetic regulations of low-temperature acclimation. We found that the global acetylation was decreased in the liver of bullfrog tadpoles acclimated to low temperature. The amounts of transcripts for two histone acetyltransferases were higher in the liver of tadpoles acclimated to low temperature than in those acclimated to warm temperature, while we observed no significant differences in the amounts of transcripts for histone deacetylases. We also found that the amounts of transcripts and acetylated histones on the specific temperature-responsive genes scd and cyp7a1 whose transcripts were increased and decreased, respectively, in response to low temperature were positively correlated. Cellular acetyl-CoA levels were higher in the liver of tadpoles acclimated to low temperature than in those acclimated to warm temperature. These results contradicted the states of histone acetylation, suggesting that bullfrog tadpoles have different epigenetic mechanisms to modify the histones when compared with those of other organisms such as reptiles and mammals, even though the relationship between the transcript amount and the states of histone acetylation on temperature-responsive genes was similar to that of mammals.


Assuntos
Aclimatação , Histonas/metabolismo , Larva/metabolismo , Fígado/metabolismo , Rana catesbeiana/metabolismo , Acetilação , Animais , Temperatura Baixa , Histona Acetiltransferases/genética , Larva/genética , Rana catesbeiana/genética
8.
Environ Pollut ; 253: 1009-1020, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31434178

RESUMO

The environment receives about 2.7 kg.ha-1 annually of pesticides, used in crop production. Pesticides may have a negative impact on environmental biodiversity and potentially induce physiological effects on non-target species. Advances in technology and nanocarrier systems for agrochemicals led to new alternatives to minimize these impacts, such as nanopesticides, considered more efficient, safe and sustainable. However, it is important to evaluate the risk potential, action and toxicity of nanopesticides in aquatic and terrestrial organisms. This study aims to evaluate genotoxic and hematological biomarkers in bullfrog tadpoles (Lithobates catesbeianus) submitted to acute exposure (48 h) to pyrethrum extract (PYR) and solid lipid nanoparticles loaded with PYR. Results showed increased number of leukocytes during acute exposure, specifically eosinophils in nanoparticle-exposed groups, and basophil in PYR-exposed group. Hematological analysis showed that PYR encapsulated in nanoparticles significantly increased the erythrocyte number compared to the other exposed groups. Data from the comet assay indicated an increase in frequency of the classes that correspond to more severe DNA damages in exposed groups, being that the PYR-exposed group showed a high frequency of class-4 DNA damage. Moreover, erythrocyte nuclear abnormalities were triggered by short-time exposure in all treatments, which showed effects significantly higher than the control group. These results showed genotoxic responses in tadpoles, which could trigger cell death pathways. Concluding, these analyses are important for applications in assessment of contaminated aquatic environments and their biomonitoring, which will evaluate the potential toxicity of xenobiotics, for example, the nanoparticles and pyrethrum extract in frog species. However, further studies are needed to better understand the effects of nanopesticides and botanical insecticides on non-target organisms, in order to contribute to regulatory aspects of future uses for these systems.


Assuntos
Chrysanthemum cinerariifolium , Larva/fisiologia , Nanopartículas/toxicidade , Extratos Vegetais/toxicidade , Rana catesbeiana/fisiologia , Xenobióticos/toxicidade , Animais , Dano ao DNA , Larva/efeitos dos fármacos
9.
Molecules ; 24(16)2019 Aug 17.
Artigo em Inglês | MEDLINE | ID: mdl-31426494

RESUMO

Infections caused by multidrug-resistant bacteria are a global emerging problem. New antibiotics that rely on innovative modes of action are urgently needed. Ranalexin is a potent antimicrobial peptide (AMP) produced in the skin of the American bullfrog Rana catesbeiana. Despite strong antimicrobial activity against Gram-positive bacteria, ranalexin shows disadvantages such as poor pharmacokinetics. To tackle these problems, a ranalexin derivative consisting exclusively of d-amino acids (named danalexin) was synthesized and compared to the original ranalexin for its antimicrobial potential and its biodistribution properties in a rat model. Danalexin showed improved biodistribution with an extended retention in the organisms of Wistar rats when compared to ranalexin. While ranalexin is rapidly cleared from the body, danalexin is retained primarily in the kidneys. Remarkably, both peptides showed strong antimicrobial activity against Gram-positive bacteria and Gram-negative bacteria of the genus Acinetobacter with minimum inhibitory concentrations (MICs) between 4 and 16 mg/L (1.9-7.6 µM). Moreover, both peptides showed lower antimicrobial activities with MICs ≥32 mg/L (≥15.2 µM) against further Gram-negative bacteria. The preservation of antimicrobial activity proves that the configuration of the amino acids does not affect the anticipated mechanism of action, namely pore formation.


Assuntos
Aminoácidos/química , Peptídeos Catiônicos Antimicrobianos/farmacologia , Peptídeos Cíclicos/farmacologia , Proteínas Citotóxicas Formadoras de Poros/farmacologia , Acinetobacter baumannii/efeitos dos fármacos , Acinetobacter baumannii/crescimento & desenvolvimento , Sequência de Aminoácidos , Animais , Peptídeos Catiônicos Antimicrobianos/síntese química , Peptídeos Catiônicos Antimicrobianos/farmacocinética , Disponibilidade Biológica , Enterococcus faecium/efeitos dos fármacos , Enterococcus faecium/crescimento & desenvolvimento , Escherichia coli/efeitos dos fármacos , Escherichia coli/crescimento & desenvolvimento , Compostos Heterocíclicos/administração & dosagem , Rim/diagnóstico por imagem , Rim/efeitos dos fármacos , Rim/metabolismo , Klebsiella pneumoniae/efeitos dos fármacos , Klebsiella pneumoniae/crescimento & desenvolvimento , Masculino , Testes de Sensibilidade Microbiana , Compostos Organometálicos/administração & dosagem , Peptídeos Cíclicos/síntese química , Peptídeos Cíclicos/farmacocinética , Proteínas Citotóxicas Formadoras de Poros/síntese química , Proteínas Citotóxicas Formadoras de Poros/farmacocinética , Tomografia por Emissão de Pósitrons , Compostos Radiofarmacêuticos/administração & dosagem , Rana catesbeiana , Ratos , Ratos Wistar , Staphylococcus aureus/efeitos dos fármacos , Staphylococcus aureus/crescimento & desenvolvimento , Estereoisomerismo
10.
Dis Aquat Organ ; 135(2): 135-150, 2019 Aug 08.
Artigo em Inglês | MEDLINE | ID: mdl-31392966

RESUMO

American bullfrogs Lithobates catesbeianus are thought to be important in the global spread of ranaviruses-often lethal viruses of cold-blooded vertebrates-because they are commonly farmed, dominate international trade, and may be 'carriers' of ranavirus infections. However, whether American bullfrogs are easily infected and maintain long-lasting ranavirus infections, or are refractory to or rapidly clear infections, remains unknown. We tracked the dynamics of ranavirus in American bullfrogs through time and with temperature in multiple types of samples and also screened shipments from commercial suppliers to determine whether we could detect subclinical infections. Collectively, we found that tadpoles and juveniles were commonly infected at moderate doses, and while some died, others controlled and appeared to clear their infections. Some individuals, however, harbored subclinical infections for up to 49 d, suggesting that American bullfrogs may be important carriers. Indeed, tadpoles and metamorphosed frogs from 2 of 5 commercial suppliers harbored subclinicial infections. Juveniles at warmer temperatures had less intense but still persistent infections. Because diagnostic performance was strongly related to infection intensity, non-lethal samples (i.e. tail or toe clips, swabs, and environmental DNA) had only a moderate chance of detecting subclinical infections. Even internal tissues may fail to detect subclinical infections. However, viral shedding was correlated with the intensity of infection, so while subclinically infected tadpoles shed virus for 35-49 d, the low levels might lead to little transmission. We suggest that a quantitative focus on virus dynamics within hosts can provide a more nuanced view of ranavirus infections and the risk presented by American bullfrogs in trade.


Assuntos
Infecções por Vírus de DNA , Ranavirus , Animais , Anuros , Infecções por Vírus de DNA/veterinária , Larva , Rana catesbeiana , Estados Unidos
11.
Ecotoxicol Environ Saf ; 182: 109446, 2019 Oct 30.
Artigo em Inglês | MEDLINE | ID: mdl-31323523

RESUMO

Increased use of sugarcane pesticides and their destination to non-target environments in Brazil has generated concerns related to the conservation of more vulnerable groups, such as amphibians. Besides the high skin permeability, tadpoles are constantly restricted to small and ephemeral ponds, where exposure to high concentrations of pesticides in agricultural areas is inevitable. This study evaluated chronic effects caused by sub-lethal concentrations of 2,4-dichlorophenoxyacetic acid herbicide on energy storage, development, respiration rates, swimming performance and avoidance behavior of bullfrog tadpoles (Lithobates catesbeianus). Firstly, we conducted acute toxicity test (96 h) to estipulate sub-lethal concentrations of 2,4-D and evaluate the sensitivity of three tadpoles' species to this herbicide. Results showed that Leptodactylus fuscus presented the lowest LC50 96 h, 28.81 mg/L, followed by Physalaemus nattereri (143.08 mg/L) and L. catesbeianus (574.52 mg/L). Chronic exposure to 2,4-D (125, 250 and 500 µg/L) delayed metamorphosis and inhibited the growth of tadpoles at concentrations of 125 µg/L. Effects on biochemical reserves showed that 2,4-D increased total hepatic lipids in tadpoles, although some individual lipid classes (e.g. free fatty acids and triglycerides) were reduced. Protein and carbohydrates contents were also impaired by 2,4-D, suggesting a disruption on energy metabolism of amphibians by the herbicide. In addition to biochemical changes, respiration rates and swimming speed were also decreased after chronic exposure to 2,4-D, and these responses appeared to be correlated with the changes detected in the basic energy content. Avoidance test indicated that tadpoles of L. catesbeinus avoided the presence of 2,4-D, however they were unable to detect increasing gradients of the contaminant. Our data showed that chronic exposure to 2,4-D impaired biochemical, physiological and behavioral aspects of tadpoles, which may compromise their health and make them more vulnerable to environmental stressors in natural systems.


Assuntos
Ácido 2,4-Diclorofenoxiacético/toxicidade , Aprendizagem da Esquiva/efeitos dos fármacos , Metabolismo Energético/efeitos dos fármacos , Herbicidas/toxicidade , Larva/efeitos dos fármacos , Taxa Respiratória/efeitos dos fármacos , Poluentes Químicos da Água/toxicidade , Animais , Brasil , Relação Dose-Resposta a Droga , Larva/metabolismo , Metamorfose Biológica/efeitos dos fármacos , Rana catesbeiana , Natação , Testes de Toxicidade Aguda
12.
Chemosphere ; 236: 124350, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31319302

RESUMO

Discovery of elevated concentrations of perfluoroalkyl substances (PFAS) in ground and surface waters globally has heightened concern over their potential adverse health effects. The effects of PFAS are known largely from acute toxicity studies of single PFAS compounds in model organisms, while little is understood concerning effects of mixtures on wildlife. To address this gap, we examined the acute and chronic effects of two of the most common PFAS (perfluorooctanesulfonic acid [PFOS] and perfluorooctanoic acid [PFOA]) and their mixtures on survival, growth, and development of American bullfrog (Rana catesbeiana) tadpoles. In 96 h acute toxicity tests, PFOS was 10X more toxic than PFOA and effects of the two chemicals in combination appeared additive. The effects of PFOS, PFOA, and their interaction varied by the sublethal endpoint under consideration in a 72 d exposure. Effects of PFAS on tadpole mass and developmental stage were largely driven by PFOS and there was no evidence of interactions suggesting deviations from additivity. However, for snout-vent length, reductions in length in mixture treatments were greater than expected based on the effects of the two chemicals independently (i.e. non-additivity). Further, effects on snout-vent length in single chemical exposures were only observed with PFOA. Our results highlight the importance of assessing combined effects of PFAS co-occurring in the environment and suggest caution in extrapolating the effects of acute toxicity studies to more environmentally relevant exposures. Future studies examining effects of environmentally relevant mixtures on wildlife will be essential for effective environmental risk assessment and management.


Assuntos
Ácidos Alcanossulfônicos/toxicidade , Caprilatos/toxicidade , Fluorcarbonetos/toxicidade , Larva/crescimento & desenvolvimento , Rana catesbeiana/anormalidades , Rana catesbeiana/embriologia , Animais , Exposição Ambiental , Estados Unidos
13.
Respir Physiol Neurobiol ; 268: 103251, 2019 10.
Artigo em Inglês | MEDLINE | ID: mdl-31279052

RESUMO

Bullfrog tadpoles ventilate both the buccal cavity and lung. In isolated brainstems, the midbrain/pons influences CO2 responsiveness and timing of lung ventilatory bursting, depending on larval development. However, little is known about midbrain/pons influences on buccal burst patterns. As such, we investigated how removal of this region affects buccal burst shape and CO2 responsiveness across development. We measured facial nerve activity in brainstems isolated from tadpoles during early and late developmental stages, under normal and elevated levels of CO2. Brainstems were either left intact or transected by removing the midbrain/pons. In late stage preparations, buccal burst pattern differed between intact and reduced preparations, and bursts were responsive to elevated CO2 in these reduced preparations. These results suggest the midbrain/pons affects tadpole buccal burst pattern and CO2 responsiveness, perhaps similar to its influences on lung ventilation.


Assuntos
Tronco Encefálico/fisiologia , Dióxido de Carbono , Larva/fisiologia , Metamorfose Biológica/fisiologia , Periodicidade , Rana catesbeiana/fisiologia , Respiração , Animais
14.
Biomed Microdevices ; 21(3): 76, 2019 07 25.
Artigo em Inglês | MEDLINE | ID: mdl-31346747

RESUMO

Selective stimulation of the nervous system is an important way to improve the therapeutic efficacy and minimize side effects. This paper introduces an improved method using combined electrical and near-infrared stimulation to realize selective excitation and inhibition of different sciatic nerve branches. Both the electrical stimulation and the near-infrared laser are added to the main trunk of the sciatic nerve, and gold nanorods are injected into the light irradiation point of the nerve to increase the absorption of light. Two cuff recording electrodes are added to the two sciatic nerve branches, respectively. The compound nerve action potential recorded by the cuff electrode is transmitted to the physiological signal instrument. In the experiment, selective activation and inhibition of the two nerve branches are achieved by adjusting the electrical stimulation parameters, the light stimulus parameters and the location of the light. These results demonstrate that combined electrical and near-infrared stimulation, which can effectively activate or suppress the different nerve fibers in the nerve fiber bundle, is suitable for selective regulation of peripheral nerve. Meanwhile, the photoelectric combined stimulation can reduce both the electrical energy and light energy needed for the stimulation, and reduce the electrical damage and light damage to the nerve.


Assuntos
Estimulação Elétrica/métodos , Ouro/química , Raios Infravermelhos , Nanotubos , Nervo Isquiático/fisiologia , Nervo Isquiático/efeitos da radiação , Animais , Rana catesbeiana
15.
Environ Pollut ; 251: 879-884, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31234253

RESUMO

Genotoxic analyses are commonly used in ecotoxicological studies as early biomarkers to investigate the potential effects of environmental contaminants on biological models. Several pollutants can induce DNA damage and, therefore, counting micronuclei and other nuclear abnormalities are efficient tools to evaluate genotoxicity. Some pollutants such as 4-nonylphenol (NP), a detergent used mainly in industries, and Cyproterone Acetate (CPA), an antiandrogenic medicine, have already shown genotoxic effects on some vertebrates. However, although amphibians are considered bioindicators of environmental quality and their populations are declining worldwide, the effects of these compounds on anurans are not yet known and, therefore, we believe that it is important to investigate such effects on anurans. Since water contamination is one of the ultimate causes of amphibian decline, ecotoxicological studies are important to discuss the appropriate solutions to avoid species extinction. Thus, this study investigates the genotoxic effects on Rana catesbeiana tadpoles and juveniles after being exposed to 1, 10 and 100 µg/L NP and 0.025, 0.25 and 2.5 ng/L CPA, by counting the nuclear abnormalities after exposure. The laboratory experiments lasted 28 days. The experimental conditions were the same except for the water volume since tadpoles and juveniles exhibit different habits at different developmental stages. Compared to juveniles, tadpoles were more susceptible to both compounds as indicated by the increased nuclear abnormalities observed in the highest NP concentration and all tested CPA concentrations. The juveniles, on the other hand, responded only to the two highest CPA concentrations. We concluded that CPA, even at very low concentrations, is extremely harmful to both anuran developmental stages and, particularly, to tadpoles. The significant effects observed on tadpoles is an important outcome of this study since 100 µg/L or higher NP concentrations are frequently detected in the environment.


Assuntos
Anuros/embriologia , Acetato de Ciproterona/toxicidade , Larva/efeitos dos fármacos , Fenóis/toxicidade , Rana catesbeiana/embriologia , Poluentes Químicos da Água/toxicidade , Animais , Anuros/genética , Núcleo Celular/efeitos dos fármacos , Dano ao DNA/efeitos dos fármacos , Dano ao DNA/genética , Poluição Ambiental , Larva/crescimento & desenvolvimento , Rana catesbeiana/genética
16.
Environ Sci Pollut Res Int ; 26(22): 22209-22219, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31152429

RESUMO

Endocrine disrupting chemicals are one of the most important factors contributing to worldwide amphibian decline. The 4-nonylphenol (NP) is a degradation product of several compounds, such as detergents and pesticides, affecting the aquatic environment. Here, we test whether treatment with NP has an effect on developing ovarian tissue, nuclear abnormalities in erythrocytes, and body darkness in pre-metamorphic tadpoles of the bullfrog Lithobates catesbeianus. Tadpoles were exposed for 14 days to three different concentrations of NP (1, 10, and 100 µg/L) besides the control group, which was maintained only with water. After determining body coloration, animals were euthanized and gonads and blood were collected and processed for histology and genotoxic analysis. Even though most animals were females, intersex tadpoles were observed in control and treated groups and there were no males in any group. The highest concentration of NP showed an increase in atretic oocytes, but the area corresponding to somatic compartment and early and late germ cells were not affected. Furthermore, all treated groups presented higher amount of nuclear abnormalities in erythrocytes and body darkening when compared with the control group. These results suggest that NP causes genetic damage and morphological alterations in L. catesbeianus tadpoles by disrupting oogenesis, inducing genotoxicity and increasing body coloration. Its effects on gonadal development could cause future impairments in reproduction, while its deleterious effects on genotoxicity and body pigmentation could be used as a biomarker of effect to this compound.


Assuntos
Gônadas/efeitos dos fármacos , Larva/efeitos dos fármacos , Animais , Dano ao DNA , Feminino , Masculino , Fenóis/química , Rana catesbeiana , Diferenciação Sexual
17.
Biomed Pharmacother ; 117: 109103, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31203130

RESUMO

Bullfrog oil, an animal oil extracted from the adipose tissue of Rana catesbeiana Shaw, showed promising cytotoxic activity against melanoma cells and, therefore, has the potential to become a pharmaceutical active compound. However, there is a lack of information regarding the pathways involved in its pharmacological activity. Thus, the aim of this study was to investigate and elucidate the cytotoxic effect of this oil against A2058 human melanoma cells. The cytotoxic potential was evaluated by the MTT assay, the cell cycle analysis and the cell death assay. In addition, the apoptotic potential was investigated by (i) the DNA fragmentation using propidium iodide staining analysis, (ii) the evaluation of mitochondrial membrane potential and (iii) the determination of intracellular Reactive Oxygen Species (ROS) level. The results showed that the bullfrog oil was able to promote a time-dependent cytotoxic effect, decreasing cell viability to 38% after 72 h of treatment without affecting the cell cycle. Additionally, the bullfrog oil induced the apoptosis in A2058 cells, increasing up to 50 ±â€¯13% of the intracellular ROS level, maintaining the DNA integrity and promoting an approximate decrease of 35 ±â€¯5% in the mitochondrial membrane potential. It can be concluded that the in vitro cytotoxic effect of the bullfrog oil in A2058 human melanoma cells is mediated by oxidative stress that induces mitochondrial dysfunction, triggering the apoptosis. These unprecedented results highlight the pharmacological potential of bullfrog oil and provide important information to support studies on the development of new pharmaceutical products for complementary and alternative treatments for melanoma.


Assuntos
Apoptose/efeitos dos fármacos , Melanoma/patologia , Mitocôndrias/patologia , Óleos/farmacologia , Estresse Oxidativo/efeitos dos fármacos , Rana catesbeiana/metabolismo , Animais , Ciclo Celular/efeitos dos fármacos , Linhagem Celular Tumoral , Linhagem da Célula/efeitos dos fármacos , Humanos , Potencial da Membrana Mitocondrial/efeitos dos fármacos , Mitocôndrias/efeitos dos fármacos , Mitocôndrias/metabolismo , Espécies Reativas de Oxigênio/metabolismo
18.
Environ Sci Pollut Res Int ; 26(23): 23242-23256, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31190300

RESUMO

The aim of this study was to verify the effects of the isolated forms of Boral® SC 500, Glifosato® Biocarb herbicides, and a blend of both herbicides on metabolism and oxidative balance markers of Rana catesbeiana tadpoles and on their nutritional condition. Groups of tadpoles were divided into different treatments: control (no herbicides), Boral® 500 SC (sulfentrazone: 130 µg/L), Glifosato® Biocarb (glyphosate: 234 µg/L), and a blend of both herbicides. After 7 days, the liver, caudal muscle, and blood samples were taken to subsequently perform the biomarkers determination by spectrophotometry. The intestinal condition factor increased in animals exposed to glyphosate and herbicide blends, suggesting a hyperphagic effect. This hypothesis was confirmed by the rise of triglycerides and circulating very low-density lipoprotein (VLDL). There was a significant increase in the levels of uric acid in tadpoles exposed to the herbicide blend. Corticosterone levels reduced significantly in animals exposed to glyphosate and the herbicide blend. Oxidative stress markers had a tissue-dependent response. In the liver, glutathione S-transferase increased, and superoxide dismutase and catalase decreased in animals exposed to sulfentrazone and glyphosate. Lipoperoxidation was reduced in the glyphosate treatment. In the caudal muscle, superoxide dismutase and catalase activities were maintained, and there was a decline in the levels of glutathione S-transferase and TBARS only in the blend group.


Assuntos
Glicina/análogos & derivados , Herbicidas/toxicidade , Larva/efeitos dos fármacos , Estresse Oxidativo/efeitos dos fármacos , Sulfonamidas/toxicidade , Triazóis/toxicidade , Poluentes Químicos da Água/toxicidade , Animais , Biomarcadores/metabolismo , Relação Dose-Resposta a Droga , Glicina/metabolismo , Glicina/toxicidade , Herbicidas/metabolismo , Larva/metabolismo , Fígado/efeitos dos fármacos , Fígado/metabolismo , Músculos/efeitos dos fármacos , Músculos/metabolismo , Rana catesbeiana , Sulfonamidas/metabolismo , Triazóis/metabolismo , Poluentes Químicos da Água/metabolismo
19.
Sci Adv ; 5(6): eaax2650, 2019 06.
Artigo em Inglês | MEDLINE | ID: mdl-31223657

RESUMO

Dinoflagelates and cyanobacteria produce saxitoxin (STX), a lethal bis-guanidinium neurotoxin causing paralytic shellfish poisoning. A number of metazoans have soluble STX-binding proteins that may prevent STX intoxication. However, their STX molecular recognition mechanisms remain unknown. Here, we present structures of saxiphilin (Sxph), a bullfrog high-affinity STX-binding protein, alone and bound to STX. The structures reveal a novel high-affinity STX-binding site built from a "proto-pocket" on a transferrin scaffold that also bears thyroglobulin domain protease inhibitor repeats. Comparison of Sxph and voltage-gated sodium channel STX-binding sites reveals a convergent toxin recognition strategy comprising a largely rigid binding site where acidic side chains and a cation-π interaction engage STX. These studies reveal molecular rules for STX recognition, outline how a toxin-binding site can be built on a naïve scaffold, and open a path to developing protein sensors for environmental STX monitoring and new biologics for STX intoxication mitigation.


Assuntos
Proteínas de Transporte/metabolismo , Saxitoxina/metabolismo , Sequência de Aminoácidos , Animais , Sítios de Ligação/efeitos dos fármacos , Sítios de Ligação/fisiologia , Linhagem Celular , Cianobactérias/metabolismo , Humanos , Peptídeo Hidrolases/metabolismo , Inibidores de Proteases/farmacologia , Ligação Proteica/efeitos dos fármacos , Ligação Proteica/fisiologia , Rana catesbeiana , Células Sf9 , Canais de Sódio/metabolismo , Tireoglobulina/metabolismo , Transferrina/metabolismo
20.
Chemosphere ; 234: 520-527, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31229713

RESUMO

The occurrence and quantities of ARGs in extracellular and intracellular DNA (eARGs and iARGs) from sediments collected in two different types of aquaculture farms were investigated. A total of 20 ARG subtypes associated with 7 categories of commonly used antibiotics (e.g., aminoglycosides, beta-lactams, sulfonamides, tetracyclines) were identified, and some of these subtypes were not related to the antibiotics used. ARGs are mainly present in the iDNA form with the ratio of the total iARGs to eARGs being in the range of 7.9-45.5. The ratio of eARG to iARGs varies greatly with ARG subtypes, probably due to their differences in persistence as a part of eDNA. Significant correlation between int1 and ARGs was observed for both eDNA and iDNA in sediments from the aquaculture farms. Moreover, ARG pollution was more serious in bullfrog ponds than polyculture ponds due to the more frequent use of antibiotics in bullfrog rearing operations.


Assuntos
Aquicultura/métodos , DNA/genética , Resistência Microbiana a Medicamentos/genética , Tanques/química , Animais , Antibacterianos/farmacologia , Fazendas , Genes Bacterianos/efeitos dos fármacos , Sedimentos Geológicos/química , Rana catesbeiana , Tetraciclinas , beta-Lactamas
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