US EPA

7449703 

Journal Article 

Role of B-esterases in assessing toxicity of organophosphorus (chlorpyrifos, malathion) and carbamate (carbofuran) pesticides to Daphnia magna 

Barata, C; Solayan, A; Porte, C 

2004 

Yes 

Aquatic Toxicology
ISSN: 0166-445X
EISSN: 1879-1514 

Elsevier 

66 

2 

125-139 

English 

15036868 

10.1016/j.aquatox.2003.07.004 

WOS:000220007000002 

In this study, the cladoceran Daphnia magna was exposed to two model organophosphorous and one carbamate pesticides including malathion, chlorpyrifos and carbofuran to assess acetylcholinesterase (AChE) and carboxylesterase (CbE) inhibition and recovery patterns and relate those responses with individual level effects. Our results revealed differences in enzyme inhibition and recovery patterns among the studied esterase enzymes and pesticides. CbE was more sensitive to organophosphorous than AChE, whereas both CbE and AChE showed equivalent sensitivities to the carbamate carbofuran. Recovery patterns of AChE and CbE activities following exposure to the studied pesticides were similar with 80-100% recoveries taking place 12 and 96 h after exposure to organophosphorous and carbamates pesticides, respectively. The physiological role of AChE and CbE inhibition patterns in Daphnia was examined by using organophosphorous and carbamate compounds alone and with specific inhibitors of CbE. Under exposure to organophosphorous pesticides, survival of Daphnia juveniles was impaired at AChE inhibition levels higher than 50% whereas under exposure to the carbamate carbofuran low levels of AChE inhibition affected mortality. Inhibition of CbE by 80-90% increased toxicity to organophosphorous and carbamate pesticides by up to two- and four-fold, respectively. Our results suggest that both AChE and CbE enzymes are involved in determining toxicity of Daphnia to the studied chemicals and that AChE inhibition levels higher than 50% can be considered of environmental concern to Daphnia species. 

Acetylcholinesterase; Carbofuran; Carboxylesterase; Chlorpyrifos; Daphnia; Malathion; acetylcholinesterase; carbamate pesticide; carbamic acid derivative; carboxylesterase; chlorpyrifos; esterase; malathion; organophosphate insecticide; pesticide; enzyme; pesticide; toxicity test; animal experiment; article; Daphnia; environmental factor; enzyme inhibition; mortality; nonhuman; priority journal; toxicity; Cladocera; Daphnia; Daphnia magna