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Evaluation of microplastic toxicity in accordance with different sizes and exposure times in the marine copepod Tigriopus japonicus
Summary
Researchers exposed marine copepods to polystyrene microbeads of two different sizes to understand how particle size and exposure duration affect toxicity. They found that both nano-sized and micro-sized particles increased reactive oxygen species levels inside cells and altered antioxidant gene expression and enzyme activity. The study provides important molecular-level evidence that microplastic toxicity in marine organisms depends on both the size of the particles and how long organisms are exposed.
The indiscriminate use of plastic has greatly increased microplastic contamination risk in the marine environment. Microplastics can affect all marine life via the food web, from primary producers (e.g., microalgae) to final consumers (e.g., carnivorous fish). Thus, several studies have attempted to evaluate microplastic toxicity, but information about the underlying mechanisms of their effect is limited. Therefore, in this study, we examined multiple factors that could contribute to microplastic-induced toxicity. We investigated the potential molecular effects of microplastic size and exposure time. We exposed the marine copepod Tigriopus japonicus to 50 nm and 10 μm polystyrene microbeads. We found that both size and exposure time increased intracellular levels of reactive oxygen species. In addition, antioxidant-related gene expression was modulated and antioxidant enzyme activities were changed significantly. The results of this study provide important insights into the molecular mechanisms of microplastic-induced toxicity in a marine organism.