Enantioselective toxicity of 3,4-methylenedioxypyrovalerone in Daphnia magna: Assessment of morphophysiological, behavioural, biochemical and reproductive responses

Le résumé fourni par la source

The enantioselective toxicity of 3,4-methylenedioxypyrovalerone (MDPV) remains unexplored in freshwater organisms. This study investigated the effects of MDPV racemate and its enantiomers in Daphnia magna using two approaches: ( i ) an 8-day sub-chronic assay focused on early development stages; and ( ii ) the standard 21-day reproduction assay. The sub-chronic assay tested two environmental concentrations (0.10 and 1.0 μg L −1 ), for both racemate or individual enantiomers, and at a higher sublethal concentration of 10 μg L −1 for the racemate. Survival, morphophysiological, behavioural, reproductive, and biochemical responses were evaluated. The reproduction assay tested concentrations from 0.10 to 1.79 μg L −1 , and evaluated survival, body size, and reproductive effects. Sub-chronic exposure to 10 μg L −1 ( R , S )-MDPV decreased survival. MDPV racemate and its enantiomers changed morphophysiological parameters, except for body growth. In juveniles, the heart area increased with 0.10 μg L −1 of ( R )-MDPV whereas the heart size decreased with 0.10 and 1.0 μg L −1 of ( S )-MDPV. Enantioselective effects were observed in swimming behaviour: ( S )-MDPV increased speed and ( R )-MDPV increased active time. No effects were observed in biochemical (except in reactive oxygen species for ( S )-MDPV) and early reproductive parameters. The reproduction assay revealed enhanced growth in all MDPV forms (except at 0.56 μg L −1 ). A nonsignificant reduction in survival to the higher concentrations of ( R )-MDPV was accompanied by reduced reproductive output (at 1.00 and 1.79 μg L −1 ) and intrinsic rate of population increase (at 1.79 μg L −1 ). Our findings suggest that, in general, ( S )-MDPV triggers more severe sub-chronic effects, whereas ( R )-MDPV is associated with harmful effects for longer time exposure. • Racemate and both enantiomers altered heart rate, heart size and area. • MDPV racemate significantly reduced survival at 10 μg L −1 . • Enantioselectivity was observed in the heart area and swimming behaviour. • ( R )-MDPV at 1.79 μg L −1 decreased reproductive output and population growth rate. • ( S )-MDPV linked to sub-chronic impacts and ( R ) to longer-term reproductive effects.

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