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2.
Environ Pollut ; 252(Pt B): 1257-1266, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31252123

RESUMO

This study assesses for the first time the ingestion of microplastics by giant clams and evaluates their importance as a sink for this pollutant. A total of 24 individuals of two size classes were collected from the Red Sea and then exposed for 12 days to 4 concentrations of polyethylene microbeads ranging from 53 to 500 µm. Experiments revealed that clams actively take up microplastic from the water column and the average of beads retained inside the animal was ∼7.55 ±â€¯1.89 beads individual -1 day -1 (5.76 ±â€¯1.16 MPs/g dw). However, the digestive tract itself cannot be considered the only sink of microbeads in Tridacnids. Indeed, shells play a key role as well. The abundance of microplastic adhering to the shells, which was estimated directly, was positively correlated to the concentration of beads found in the surrounding seawater. Therefore, clams' shells contribute to the removal of 66.03 ±â€¯2.50% of the microplastic present in the water column. Furthermore, stress responses to the exposure to polyethylene were investigated. Gross Primary Production:Respiration (GPP:R) ratio decreased throughout of the experiment, but no significant difference was found between treatments and controls.


Assuntos
Biodegradação Ambiental , Bivalves/metabolismo , Monitoramento Ambiental , Polietileno/análise , Poluentes Químicos da Água/análise , Animais , Oceano Índico , Alimentos Marinhos , Água do Mar/química
3.
Artigo em Inglês | MEDLINE | ID: mdl-29412870

RESUMO

In vitro models are emerging tools for reducing reliance on traditional toxicity tests, especially in areas where information is sparse. For studies of fish, this is especially important for extrahepatic organs, such as the intestine, which, until recently, have been largely overlooked in favour of the liver or gill. Considering the importance of dietary uptake of contaminants, the rainbow trout (Oncorhynchus mykiss) intestine-derived cell line RTgutGC was cultured, to test its suitability as a high-throughput in vitro model. Benzo[a]pyrene (B[a]P) is an important contaminant and a model polycyclic aromatic hydrocarbon (PAH). Over 48 h exposure, a range of endpoints and xenobiotic metabolism rates were examined at three different pH levels indicative of the in vitro (pH 7.5) and in vivo mid-gut (pH 7.7) and hind-gut (pH 7.4) regions as a function of time. These endpoints included (i) cell viability: acid phosphatase (APH) and lactate dehydrogenase (LDH) assays; (ii) glucose uptake; (iii) cytochrome P450 enzyme activity: 7-ethoxyresoorufin-O-deethylase (EROD) assay; (iv) glutathione transferase (GST) activity; (v) genotoxic damage determined using the comet assay. Absence of cell viability loss, in parallel with decrease in the parent compound (B[a]P) in the medium and its subsequent increase in the cells suggested active sequestration, biotransformation, and removal of this representative PAH. With respect to genotoxic response, significant differences were observed at both the sampling times and the two highest concentrations of B[a]P. No significant differences were observed for the different pH conditions. Overall, this in vitro xenobiotic metabolism system appears to be a robust model, providing a basis for further development to evaluate metabolic and toxicological potential of contaminants without use of animals.


Assuntos
Benzo(a)pireno/toxicidade , Intestinos/citologia , Oncorhynchus mykiss/crescimento & desenvolvimento , Animais , Linhagem Celular , Sobrevivência Celular/efeitos dos fármacos , Poluentes Ambientais/toxicidade , Ensaios de Triagem em Larga Escala , Concentração de Íons de Hidrogênio , Técnicas In Vitro , Intestinos/efeitos dos fármacos , Modelos Biológicos , Testes de Mutagenicidade , Oncorhynchus mykiss/genética
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