TY - JOUR
T1 - Malathion toxicity and carboxylesterase activity in Drosophila melanogaster
AU - Ashour, Mohamed Bassem A.
AU - Harshman, Lawrence G.
AU - Hammock, Bruce D.
N1 - Funding Information:
This study was supported by NIH Grant ES01710-07. We appreciate the generous technical assistance from Mrs. Shirley Gee and are grateful to Mrs. Peggy Kaplan for typing the manuscript.
PY - 1987/10
Y1 - 1987/10
N2 - Adults from nine strains of Drosophila melanogaster were exposed to a residual film of malathion. The LC50 values indicated that there was a fourfold difference in susceptibility to malathion among the strains. 3-Nonylthio-1,1,1-trifluoropropan-2-one (NTFP), a carboxylesterase inhibitor, synergized the toxicity of the insecticide when four fly strains were exposed to a mixture of the inhibitor and malathion. Whole-body homogenates of adults were analyzed by wide-range isoelectric focusing (IEF). Carboxylesterase activities on the gels were stained using common substrates such as α- and β-naphthyl acetate and p-nitrophenyl acetate. Less conventional substrates, ethyl and isobutyl carbonates of α-naphthol and p-nitrophenol, were synthesized and used for staining gels and kinetics in solution. Two major bands of activity (pI 4.4 and 4.0) were detected with naphthyl substrates. A major peak of malathion hydrolytic activity (pI 6.3) was detected by running spectrophotometric assays for carboxylesterase activity on malathion using IEF gel slices and a rapid, semiautomated assay method. The peak region of activity on malathion did not coincide with bands obtained when naphthyl substrates were used to stain the gels. NTFP inhibited malathion hydrolysis in a solution from the IEF peak of activity and also inhibited esterase activity on α-naphthyl acetate on the gels. Recovered carboxylesterase activities on malathion and O-ethyl carbonate of p-nitrophenol were higher in the cytosolic than in the microsomal or mitochondrial cell fractions.
AB - Adults from nine strains of Drosophila melanogaster were exposed to a residual film of malathion. The LC50 values indicated that there was a fourfold difference in susceptibility to malathion among the strains. 3-Nonylthio-1,1,1-trifluoropropan-2-one (NTFP), a carboxylesterase inhibitor, synergized the toxicity of the insecticide when four fly strains were exposed to a mixture of the inhibitor and malathion. Whole-body homogenates of adults were analyzed by wide-range isoelectric focusing (IEF). Carboxylesterase activities on the gels were stained using common substrates such as α- and β-naphthyl acetate and p-nitrophenyl acetate. Less conventional substrates, ethyl and isobutyl carbonates of α-naphthol and p-nitrophenol, were synthesized and used for staining gels and kinetics in solution. Two major bands of activity (pI 4.4 and 4.0) were detected with naphthyl substrates. A major peak of malathion hydrolytic activity (pI 6.3) was detected by running spectrophotometric assays for carboxylesterase activity on malathion using IEF gel slices and a rapid, semiautomated assay method. The peak region of activity on malathion did not coincide with bands obtained when naphthyl substrates were used to stain the gels. NTFP inhibited malathion hydrolysis in a solution from the IEF peak of activity and also inhibited esterase activity on α-naphthyl acetate on the gels. Recovered carboxylesterase activities on malathion and O-ethyl carbonate of p-nitrophenol were higher in the cytosolic than in the microsomal or mitochondrial cell fractions.
UR - http://www.scopus.com/inward/record.url?scp=0023551241&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0023551241&partnerID=8YFLogxK
U2 - 10.1016/0048-3575(87)90067-8
DO - 10.1016/0048-3575(87)90067-8
M3 - Article
AN - SCOPUS:0023551241
SN - 0048-3575
VL - 29
SP - 97
EP - 111
JO - Pesticide Biochemistry and Physiology
JF - Pesticide Biochemistry and Physiology
IS - 2
ER -