Acetylcholinesterase activity in the freshwater shrimp Caridina nilotica as a biomarker of Roundup(®) herbicide pollution of freshwater systems in South Africa.
The use of Caridina nilotica whole-body acetylcholinesterase (AChE) activity as a potential biomarker of Roundup(®) pollution of aquatic ecosystems was investigated. Forty days post hatch (dph) shrimps were exposed to different concentrations of 0.0, 4.3, 6.7, 10.5, 16.4, 25.6 and 40.0 mg/L in a 96 h acute toxicity test; and 0.0, 2.2, 2.8, 3.4, 4.3 and 5.4 mg/L in a 21 d chronic toxicity test. Whole-body AChE activities were determined at the end of the exposure periods by spectrophotometric assay of sample extract; activities were then normalized against protein contents in the samples and expressed in nanomoles of substrate hydrolyzed. Results of both tests showed that AChE activity was concentration-dependent. Mean AChE activities and standard deviations (±SD) for 96 h acute toxicity were 3.6239 (± 0.4185), 3.4157 (± 1.1842), 2.537 (± 1.3989), 2.4253 (± 1.4202), 2.4127 (± 1.9097), 2.0017 (± 1.1080) and 2.316 (± 0.4001) nmol/min/mg protein; while activity levels for 21 d test were 3.6907(± 0.3401), 2.8473 (± 0.713), 2.9134 (± 0.9879), 2.6738 (± 0.7117), 2.3019 (± 0.4464) and 2.1478 (± 0.864) nmol/min/mg protein. Reference basal AChE activity for 40 dph C. nilotica based on the two control groups was estimated as 3.6907 (± 0.3401) nmol/min/mg proteins. The present work provides ecotoxicological basis for the possible use of AChE activity in C. nilotica as a biomarker for monitoring Roundup(®) pollution in freshwater systems.
Institute for Water Research, Rhodes University, Grahamstown, South Africa. kojomens2@hotmail.com
P K
PK
Mensah
W J
WJ
Muller
C G
CG
Palmer
D000110:Acetylcholinesterase / Q000378:metabolism*; D000818:Animals; D003445:Crustacea / Q000201:enzymology*; D004784:Environmental Monitoring; D005618:Fresh Water / Q000032:analysis*; D006540:Herbicides / Q000032:analysis* / Q000378:metabolism; D013019:South Africa; D014874:Water Pollutants, Chemical / Q000032:analysis* / Q000378:metabolism
D006540:Herbicides; D014874:Water Pollutants, Chemical; D000110:Acetylcholinesterase