Profenofos toxicity to the eastern rainbow fish ( Melanotaenia duboulayi )

Brain acetylcholinesterase (AChE) activity was evaluated after two different swimming tests in coho salmon (Oncorhynchus kisutch; 238 +/- 5 g) given 96-h exposures to 0, 5, 10, 20, or 40 microg/L of chlorpyrifos. Brain AChE activity decreased in a concentration-dependent manner (AChE activities were 81.8, 52.2, 37.3, and 21.3% of control for the 5, 10, 20, and 40 microg/L exposures, respectively), whereas swimming performance was impaired after a threshold of AChE impairment was reached. Specifically, for swimming performance (U(crit)) measured using the established ramp-U(crit) test (duration, 152 +/- 8 min), this threshold occurred with AChE activity of 68.5% +/- 18.1% of control. For a rapid acceleration test (U(deltav), where V represents velocity; 27.6 +/- 0.8 min), this value was 52.6% +/- 15.4% of control. Both swim protocols resulted in similar maximum swim speeds (control ramp-U(crit) and U(deltav) values of 3.44 +/- 0.09 and 3.71 +/- 0.13 body lengths/s, respectively), and performance was significantly reduced after 20 and 40 microg/L exposures in both groups (ramp-U(crit) values: 86.4 and 83.6 %, respectively, of control; U(deltav) values: 85.2 and 77.8%, rsepectively, of control). Although both tests yielded similar swim speeds, postexercise plasma lactate concentrations were greater for the U(deltav) test (11.3 +/- 0.6 vs 8.6 +/- 0.5 mmol/L), indicating a greater anaerobic effort. This increase was exaggerated after 10 microg/L of chlorpyrifos (14.6 +/- 1.3 mmol/L), indicating that anaerobic muscle was used to attain the same speed. Given the threshold relationship between AChE inhibition and swimming performance, coho salmon appear able to maintain integrated swimming activity despite significant impairment of an underlying neurological control mechanism.

Section: Relationship Between Ache Activity and Swimmingmentioning

confidence: 97%

The relationship between cholinesterase inhibition and two types of swimming performance in chlorpyrifos‐exposed coho salmon (Oncorhynchus kisutch)

Tierney

Casselman

Takeda

et al. 2007

“…Fonofos, a phosphonodithioate insecticide also known as dyfonate, is primarily applied to control insects in a number of crops and in turfs [4,17]. Profenofos is a phosphorothiolate OP compound that has been widely used in cotton-growing areas in most countries worldwide [22]. Crotoxyphos is a phosphate used as contact and stomach poison, primarily for pests on lactating dairy and beef cattle [4].…”

Section: Enantiomer Resolutionmentioning

confidence: 99%

Enantioselective acetylcholinesterase inhibition of the organophosphorous insecticides profenofos, fonofos, and crotoxyphos

Nillos

Rodrı́guez-Fuentes

Gan

et al. 2007

A large number of organophosphorous insecticides (OPs) are chiral compounds, and yet enantioselectivity in their environmental fate and effects is rarely addressed. In the present study, we isolated individual enantiomers of three OPs, profenofos, fonofos, and crotoxyphos, and evaluated enantioselectivity in their inhibition of acetylcholinesterase (AChE). Acetylcholinesterase inhibition by the enantiomers and racemates was determined in vivo in the aquatic invertebrate Daphnia magna and in Japanese medaka (Oryzias latipes) as well as in vitro with electric eel (Electrophorus electricus) and human recombinant AChEs. The overall results showed variable sensitivity between AChE enzymes from different species as well as variable magnitude of enantioselectivity in enzyme inhibition. The (-)-enantiomer of profenofos was 4.3- to 8.5-fold more inhibitory to AChE in vivo, whereas (-)-fonofos was 2.3- to 29-fold more potent than the corresponding (+)-enantiomer. The (+)-enantiomer of crotoxyphos was 1.1- to 11-fold more inhibitory to AChE than the (-)-enantiomer. In contrast, the in vitro results showed (+)-profenofos to be 2.6- to 71.8-fold more inhibitory than the (-)-enantiomer and (-)-crotoxyphos to be 1.6- to 1.9-fold more active than the (+)-enantiomer. The reversed direction of enantioselectivity observed between the in vivo and in vitro assays suggests enantioselectivity within toxicodynamic processes such as uptake, biotransformation, or elimination. Findings from the present study provide evidence of enantioselectivity in the AChE inhibition of chiral OPs in nontarget organisms and indicate the need to consider enantiomers individually when assessing environmental risk of these chiral pesticides.

“…Two commonly studied biochemical biomarkers in invertebrates are cholinesterase (ChE) and glutathione-S-transferase (GST) activity. Inhibition of ChE activity has been proposed as an effective tool for monitoring the exposure of organisms to organophosphorus and carbamate pesticides [9,10], whereas induction of GST can be suggestive of exposure to organochlorine compounds [11,12]. However, recent evidence suggests that the specificity of ChE as an indicator of exposure to organophosphorus and carbamate pesticides should be questioned, because heavy metals, surfactants, and pyrethroid pesticides can inhibit ChE activity [13,14].…”

Section: Introductionmentioning

confidence: 99%

Evaluation of sensitivity and specificity of two crustacean biochemical biomarkers

McLoughlin

Yin

Maltby

et al. 2000

128

Abstract-Biochemical biomarkers are increasingly used for environmental assessment. Although the emphasis has been on vertebrate biomarkers, invertebrates biomarkers have been developed as well. This study evaluated the usefulness of biomarker responses of freshwater invertebrates by comparing the sensitivity and specificity of endpoints at three levels of biological organization: biochemical, physiological, and individual. The study focused on the epibenthic amphipod Gammarus pulex L., and the end points were cholinesterase (ChE) and glutathione-S-transferase (GST) activity, feeding inhibition, and mortality. Chemicals representing five major classes of toxic chemicals were assessed, including zinc, linear alkylbenzene sulphonate (LAS; surfactant), lindane (organochlorine), pirimiphos-methyl (organophosphorus), and permethrin (pyrethroid). Lethality was the least sensitive endpoint, with 96-h LC50 values ranging from 2.78 g/L for permethrin to 6.31 mg/L for LAS. Comparison of the biochemical biomarkers and the sublethal feeding rate assay indicated that whereas ChE inhibition was a specific indicator of organophosphate exposure, the biochemical assay was more than 13-fold less sensitive than the feeding rate assay. The GST biomarker performed with greater sensitivity but with lower specificity compared with the ChE biomarker. However, only on exposure to lindane did the GST biomarker marginally outperform the feeding rate assay in terms of sensitivity. Feeding inhibition is both a general and a sensitive (LC50, Ͻ3%) indicator for exposure to a range of chemicals. The Gammarus sp. ChE biomarker may have utility in providing a diagnostic and rapid indicator of organophosphate exposure, but evidence from this and other studies questions the sensitivity of this biomarker in predicting sublethal, higher-order effects. The GST biomarker may provide a rapid and sensitive indicator for toxicant exposure, but it has limited use as a diagnostic tool and provides only limited improvement in sensitivity over more ecologically relevant sublethal end points (e.g., feeding rate, growth rate).