Behavioural and chronic toxicity of fullerene to Daphnia magna: Mechanisms revealed by transcriptomic analysis

Extensive application of fullerene nanoparticles (nC(60)) leads to potential environmental pollution. The acute toxic effects of nC(60) have been largely investigated, but studies of behavioural and chronic toxicity at sublethal doses are still rare and the underlying molecular mechanisms remain unknown. The present study investigated behavioural and chronic toxicity of nC(60) to Daphnia magna. The results showed that, in response to nC(60) exposure, hopping, heartbeat frequencies and feeding ability of D. magna decreased significantly, displaying negative relationship with exposure time and dose. Chronic treatments with 0.1 mg/L or 1 mg/L nC(60) for 21 days significantly reduced survival and reproduction of D. magna. These harmful effects suggested negative impacts of nC(60) on aquatic ecosystems. Moreover, transcriptome analysis showed that the behavioural and chronic toxicity of nC(60) to D. magna might be related to physiological functions such as cell structural repair, protein degradation, energy metabolism and reproduction. We found that nC(60) accumulated in guts of D. magna, which should be responsible for the decrease of food ingestion and consequently inhibiting energy intake. Deficiency of energy not only affects behaviours but also declines reproduction in D. magna. Overall, this is the first study comprehensively considered the behavioral and chronic toxicity of nC(60) to aquatic organism. The results should be helpful to better understand the ecological consequences of C-60 released into water environments. (C) 2019 Elsevier Ltd. All rights reserved.