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A feasibility study of using silkworm larvae as a novel in vivo model to evaluate the biotoxicity of ionic liquids.
Ionic liquids (ILs) have been reported to be a potential water and soil pollutant, whose toxicity has gained much attention in recent years. In this work, silkworm larvae were used as a novel in vivo model to assess the biotoxicity of ILs, which were performed by three steps. The first step was to determine the susceptibility of different silkworm strains to ILs. Data showed that Jingsong×haoyue was the most susceptible one among three silkworm strains (Jingsong×haoyue, P50, and Yi16) for evaluating the biological effects of ILs. The second step was to compare the toxicity of ILs with different structures using the larvae of Jingsong×haoyue. It was found that three representative ILs, 1-octyl-3-methylimidazole chloride ([C8mim]Cl), N-octyl-3-methylpyridine chloride ([C8mpy]Cl), and 1-octyl-3-methylimidazole tetrafluoroborate ([C8mim]BF4), had significant toxic effects on the growth and development of the larvae with 24 h median lethal concentration (24 h-LC50) values of 112.3, 156.3, and 68.9 μg g-1, respectively, indicating that the types of anions and cations had impacts on the toxicity of ILs. The last step was targeted at investigating responses of the larvae to the exposure of ILs. It was observed that remarkable physiological and biochemical responses occurred in different tissues of the larvae. For example, activities of superoxide dismutase (SOD), catalase (CAT), and peroxidase (POD) in different tissues increased significantly to form an active protective mechanism for alleviating the toxic effects of ILs. Additionally, an increase of malondialdehyde (MDA) contents was found in the larvae. The data suggested that ILs could induce lipid peroxidation and cellular damage, which may be the main reason for toxicity of ILs to the larvae. Therefore, silkworm larvae could be used as a susceptible and reliable in vivo model to evaluate the toxicity of ILs, and the results are helpful to reveal their toxic mechanism to insects.
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