Biomarkers are a widely applied approach in environmental studies. Analyses of cholinesterase (ChE), glutathione S-transferase (GST) and lipid peroxidation (LPO) are biomarkers that can provide information regarding early effects of pollutants at different biochemical levels on an organism. The aim of this study was to evaluate the biomarker approach on a Costa Rican native and relevant species. For this, larvae of gar (Atractosteus tropicus) were exposed to the organophosphorus nematicide, ethoprophos. Acute (96hr) exposure was conducted with pesticide concentrations ranging from 0.1 microg/L to 1 500 microg/L. The 96hr LC50 calculated was 859.7 microg/L. After exposure, three biomarkers (ChE, GST and LPO) were analyzed in fish that survived the acute test. The lowest observed effect concentration (LOEC) regarding ChE activity inhibition was 50 microg/L. This concentration produced a significant inhibition (p<0.05) of the enzyme by 20%. The highest concentration tested without showing any effect on ChE activity and therefore considered as no observed effect concentration (NOEC) was 10 microg/L. Ethoprophos concentration of 400 microg/L caused a ChE inhibition by 79%. In this study, no significant variations (p>0.05) in GST activity and LPO were observed in A. tropicus larvae after exposure to ethoprophos.
Title: Factors influencing the ability of Pseudomonas putida strains epI and II to degrade the organophosphate ethoprophos Karpouzas DG, Walker A Ref: J Appl Microbiol, 89:40, 2000 : PubMed
Two strains of Pseudomonas putida (epI and epII), isolated previously from ethoprophos-treated soil, were able to degrade ethoprophos (10 mg 1(-1)) in a mineral salts medium plus nitrogen (MSMN) in less than 50 h with a concurrent population growth. Addition of glucose or succinate to MSMN did not influence the degrading ability of Ps. putida epI, but increased the lag phase before rapid degradation commenced with Ps. putida epII. The degrading ability of the two isolates was lost when the pesticide provided the sole source of phosphorus. Degradation of ethoprophos was most rapid when bacterial cultures were incubated at 25 and 37 degrees C. Pseudomonas putida epI was capable of completely degrading ethoprophos at a slow rate at 5 degrees C, compared with Ps. putida epII which could not completely degrade ethoprophos at the same time. Pseudomonas putida epI was capable of degrading ethoprophos when only 60 cells ml(-1) were used as initial inoculum. In contrast, Ps. putida epII was able to totally degrade ethoprophos when inoculum densities of 600 cells ml(-1) or higher were used. In general, longer lag phases accompanied the lower inoculum levels. Both isolates rapidly degraded ethoprophos in MSMN at pHs ranging from 5.5 to 7.6, but not at pH 5 or below.
A rapid procedure has been developed that allows a single-step, selective extraction and cleanup of organophosphate (OP) pesticide residues from milk dispersed on solid-matrix diatomaceous material filled into disposable cartridges by means of light petroleum saturated with acetonitrile and ethanol. Recovery experiments were carried out on homogenized commercial milk (3.6% fat content) spiked with ethanolic solutions of 24 OP pesticides, viz., ethoprophos, diazinon, dimethoate, chlorpyrifos-methyl, parathion-methyl, chlorpyrifos-ethyl, malathion, isofenphos, quinalphos, ethion, pyrazophos, azinphosethyl, heptenophos, omethoate, fonofos, pirimiphos-methyl, fenitrothion, parathion, chlorfenvinphos, phenthoate, methidathion, triazophos, phosalone, azinphos-methyl, at levels ranging for the different OP pesticides from 0.02 mg/kg to 1.11 mg/kg. Average recoveries of four replicates were in the range 72-109% for the different OP pesticides, with relative standard deviations (R.S.D.) from ca. 1 to 19%, while dimethoate and omethoate were not recovered. Coextracted fatty material amounted to an average of about 4.0 mg/ml of milk. The extraction procedure requires about 30 min. The main advantages are that extraction and cleanup are carried out in a single step, emulsions do not occur, several samples can be run in parallel by a single operator, reusable glassware is not needed and simple operations are required.
