Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.1.1.7 (acetylcholinesterase)
 28,390 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Resistance to organophosphorous insecticides such as malathion, chlorpyrihos, and pyrimiphos-methyl; pyrethroids such as deltametrine and lambda cialotrine; and the propoxur carbamate was determined in 4 strain of Culex quinquefasciatus of the Eastern, Central and Western parts of Cuba. The increase of esterase enzymes was the main mechanism involved in resistance, followed by altered acetylcholinesterase (AChe). Gene frequencies were high for esterases (1), and moderate for acetylcholinesterase (0.52) in the four strains under study, as an average. Bioassays showed resistance to malathion and propoxur. The use of DEF as esterase inhibitor showed that pyrimiphos-methyl was not affected by this mechanism of resistance, and chlorpyriphos was slightly affected. After 5 years of using pyrethroids such as deltametrine and lambda cialotrine, these are still useful agents for the control of C. quinquefasciatus; the alternate use of these and pyrimiphos-methyl or chlorpyriphos could prevent the development of resistance in a short or medium term.
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PMID:[Determination of resistance mechanism in Culex quinquefasciatus Say 1823 and its operational implication in the correct use of insecticides for its control]. 976 46

The resistance change to different insecticides in Culex quinquesfasciatus strain select at the laboratory with doses of pyrethroid lambdacyhalothrin that would cause a larva mortality of 90% were studied. It was attained an increase of the resistance to this insecticide of 144.5 times compared with the original level, and it was obtained a resistant strain (287x). There was an increase of the levels of resistance to methyl-pyrimifos (2.4 times), propoxur (6 times), DDT (5.2 times), clorpirifos (22 time), cypermethrin (67.5 times), and deltamethrin (20.2 times). The frequencies of the genes that codify for the elevated esterases enzymes and for the modified acetylcholinesterase reached their maximum value. Significant changes were observed in the phenotypes for esterases in the electrophoresis in polyacrylamide gels. It was detected synergism of DEF and PB with lambdacyhalothrin. Therefore, the elevated esterases and the esterases of multiple function may contribute to resistance.
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PMID:[The evolution of resistance in a Culex quinquefasciatus strain starting from selection with the pyrethroid insecticide lambdacyhalothrin]. 980 56

The mechanisms of resistance in Culex quinquefasciatus from 6 municipalities of Havana City were studied in order to determine their genetic frequency. Increased esterases and altered acetylcholinesterase are still being the major resistance mechanisms in Havana City. The mechanisms of esterases is of high frequency, followed by altered acetylcholinestenase. Resistance to cholorpirifos was found for the first time in Culex quinquefasciatus, while resistance of malathion and carbamate propoxur is maintained, and deterioration to pyrethroid susceptibility is being detected. The synergistic effect of S.S.S. trubutyl phosphotritiade (DEF) and piperonil butoxide (PB) was analysed, and it was proven that esterases enzymes and multifunction oxidases are involved in the resistance to pyrethroids. By electrophoresis in polyerylamide gel, it was determined that the combination of esterases that seems to be associated with the resistance to perythroids is B1-A6-B6, which appeared with the greatest percentage. Valves of genetic frequency in the 6 municipalities were found to be high, for both esterase genes and acetylcholinesterase genes (Ache).
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PMID:[The association of resistance to organophosphate, carbamate and pyrethroid insecticides with the mechanisms of resistance observed in Culex quinquefasciatus strains from Ciudad de La Habana province]. 981 67

Two novel mechanisms of organophosphate resistance were isolated and characterized from a population of Culex pipiens L. from Cyprus. Two strains, one expressing the novel, highly active esterases A5 and B5 (strain A5B5-R), and one expressing insensitive acetylcholinesterase (strain Ace-R), were developed by single pair crosses and selection with temephos and propoxur, respectively. The A5B5-R strain demonstrated resistance toward organophosphate insecticides that could be suppressed by the esterase inhibitor S,S,S-tributyl phosphorotrithioate (DEF). No cross-resistance to carbamates occurred. The Ace-R strain demonstrated resistance to organophosphate as well as to carbamate insecticides. Propoxur and temephos resistance was not affected by the monooxygenase inhibitor piperonyl butoxide or by DEF. The Ace-R strain possessed a novel toxicologic profile as well as a unique acetylcholinesterase inhibition pattern. Inheritance of temephos or propoxur resistance was codominant in F1 offspring. Backcrosses to a susceptible strain in both cases failed to fit a single gene model, suggesting that multiple loci may be involved. Combining the A5B5-R and the Ace-R strains resulted in high levels of temephos resistance, similar to that of the parents.
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PMID:Isolation and characterization of two novel organophosphate resistance mechanisms in Culex pipiens from Cyprus. 1008 33

The cause of high resistance to chlorpyrifos observed in Tunisian Culex pipiens (L.) was investigated by comparing a Tunisian strain G (> 10,000-fold resistance), a French strain T (approximately 50-fold resistance), and a susceptible reference strain S. Strains G and T had the same level of propoxur resistance (approximately 1,000-fold) and were homozygous for an autosomal propoux-insensitive acetylcholinesterase (AChE-1). In G and T strains, as well as in the offspring of different F1s and backcrosses using these F1s and the S strain, the effect of DEF and Pb synergists on chlorpyrifos resistance was low or absent, indicating that increased detoxification by enzymes inhibited by these chemicals had a minor role. Chlorpyrifos resistance in the G strain was caused by a major gene (or group of genes) tightly linked to the Ace-1 gene (coding AChE-1 enzyme). The possibility of allelism between this gene and the Ace-1R allele present in the T strain was rejected by showing that AChE-1 inhibition by chlorpyrifos-oxon was not different between G and T mosquitoes.
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PMID:A new mechanism conferring unprecedented high resistance to chlorpyrifos in Culex pipiens (Diptera: Culicidae). 1059 83

Resistance of Culex quinquefasciatus from Miranda, Venezuela to the organophosphate insecticides malathion and chlorpirifos was higher than 30x whereas resistance to pyrethroids metylpirimifos, fention, cipametrine, deltametrine, permetrine and lambdacyalotrine and to organochlorate DDT was lower than 4x. Resistance mechanisms were analyzed with piperonyl butoxide synergist (multifunction oxidases) and S.S.S. phosphotrithiate tributyl (DEF, esterase inhibitor). Multifunction oxidases did not play a significant role in resistance to organophosphate insecticides and carbamate; however, esterases were only mechanisms of resistance to malathion and chlorpirifos. The only insecticide affected by DEF and PB was cipermetrine. Biochemical tests revealed a very low frequency of the altered acetylcholinesterase mechanism (0.13). Esterase frequencies were high (1). Electrophoresis exposed the B1, A6 and B6 esterase phenotypes.
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PMID:[Characterization of resistance to organophosphate insecticides, carbamates, and pyrethroids in Culex quinquefasciatus from the State of Miranda, Venezuela]. 1088 66

Aedes aegypti, at the larval stage, has been subjected to the temephos selection in laboratory. The level of temephos resistance was detected in a microplate by biochemical assay using WHO bioassay technique. The major enzyme-based resistance mechanisms involved in temephos resistance include elevated nonspecific esterase, oxidase and insensitive acetylcholinesterase. After 19 generations of temephos selection, the selected group showed resistance ratios of 4.64 and 16.92, when compared with a non-selected group and the WHO susceptible strain, respectively. The two seperated forms, type form and the pale form of Ae. aegypti showed low levels of resistance to temephos after 19 generations of selection, with resistance ratios of 4.82 and 4.07 for the type form and the pale form, respectively; when compared with the non-selected strain, 17.58 and 14.84, when compared with the WHO susceptible strain. This showed that the type form could develop higher level resistance than the pale form. The esterase inhibitor (S,S,S-tributyl phosphorotrithioate, DEF) or synergist implicated detoxifying esterase in all the temephos selected groups and the presence of elevated esterase were confirmed by biochemical assay. There were significant differences in elevated esterase activity between the temephos selected groups and the non-selected group. However no significant difference between the type form and the pale form was found. Besides the elevated esterase, there was no change in monooxygenase activity and no evidence of insensitive acetylcholinesterease for all temephos selected groups. These results suggest that temephos resistance could be developed in Ae. aegypti under selection pressure and that the main mechanism is based only on esterase detoxification.
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PMID:Temephos resistance in two forms of Aedes aegypti and its significance for the resistance mechanism. 1511 88

Two mosquito strains of Culex quinquefasciatus Say, MAmCq and HAmCq, were collected from Mobile and Huntsville, AL, respectively, after the control of mosquitoes with insecticides proved difficult. A synergism study showed that resistance to chlorpyrifos in MAmCq and HAmCq was not suppressed by piperonyl butoxide (PBO) and S,S,S,-tributylphosphorotrithioate (DEF), suggesting that P450 monooxygenase- and hydrolase-mediated detoxication does not contribute to chlorpyrifos resistance in either strain. Diethyl maleate (DEM) did not cause any significant change in the level of chlorpyrifos toxicity to HAmCq. However, DEM enhanced toxicity of chlorpyrifos to MAmCq 2.5-fold, indicating that glutathione S-transferase (GST)-mediated detoxication may play a minor role in the resistance of MAmCq. An inhibition study of acetylcholinesterase (AChE) by chlorpyrifos showed that bimolecular rate constants (Ki) of chlorpyrifos for the inhibition of AChE in adults and larvae of the susceptible S-Lab strain were 2.2- and 1.9-fold higher, respectively, than in the HAmCq strain and 3.4- and 3.8-fold higher than in the MAmCq strain. The single mutation, G119S, resulting from a single nucleotide polymorphism (SNP), G to A, in ace-1 acetylcholinesterase gene was present in HAmCq and MAmCq mosquitoes. The frequency of the heterozygote for the G119S mutant allele in the HAmCq and MAmCq mosquito populations was 0.25 and 0.45, respectively, and no individuals in either of these mosquito strains were homozygous for the A allele. It thus seems likely that the presence of heterozygous individuals for the G119S allele in HAmCq and MAmCq populations may be a response to the insensitivity of AChE observed in these two mosquito strains.
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PMID:Chlorpyrifos resistance in mosquito Culex quinquefasciatus. 1636 65

Various compounds were tested for effects on the toxicity of the insect repellent N, N-diethyl-m-toluamide (DEET) in German cockroaches, Blattella germanica (L.). Organophosphate and carbamate acetylcholinesterase inhibitors carbaryl, DEF, eserine (physostigmine, malathion and pyridostigmine bromide synergized DEET toxicity also synergized the toxicity of the formamidine pesticides. Amitraz and chlordimeform. Results suggest that DEET may have some toxic actions that are similar to those of formamidine pesticides. DEET synergized the toxicity of some acetylcholinesterase inhibitors but not others. Results further suggest that some mechanism other than acetylcholinesterase inhibition was responsible for the toxic interactions observed between DEET and the acetylcholinesterase inhibitors.
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PMID:Synergism of toxicity of N,N-diethyl-m-toluamide to German cockroaches (Orthoptera: Blattellidae) by hydrolytic enzyme inhibitors. 1745 Jun 48

The addition of temephos to water containers as a larvicide against Aedes aegypti was commonly used as a part of DHF control programs. The widespread, or long-term, application of insecticides can lead to the development of mosquito resistance to the insecticides through selection pressure. This presents a problem for disease control. Therefore, this study was conducted in the laboratory to observe the potential development of resistance to temephos and the mechanism involved in Ae. aegypti, and to study the significance for dengue infection. The larvae were selected in consecutive generations. The level of resistance to temephos was detected by WHO assay technique. After 19 generations of selection, a low level of resistance was found. The resistance ratio at LC50 was 4.64 when compared with the non-selected group. The assay for major enzyme-based resistance mechanisms was done in a microtiter plate to detect elevated non-specific esterases, monooxygenase, and insensitive acetylcholinesterase in the temephos-selected and non-selected groups. It revealed a significant increase in esterase activity when compared with the non-selected group. There was no elevation of monooxygenase or insensitive acetylcholinesterase activities. However, when an esterase inhibitor (S, S, S-tributyl phosphorotrithioate, or DEF) was added to temephos and the susceptibility in the selected group was studied, the resistance ratio was reduced from 16.92 to 3.57 when compared with a standard susceptible strain (Bora Bora). This indicates that the esterases play an important role in temephos resistance. Dengue-2 virus susceptibility was studied by oral feeding to females of the temephos-selected (S19) and the non-selected groups. The dissemination rates, when the titer of virus in the blood meal was 7.30 MID50/ml, were 11.11% and 9.38% for the selected and non-selected groups, respectively. When the titer of virus in the blood meal was 8.15 MID50/ml, the dissemination rates increased to 24.24% and 33.33%, respectively. A statistical difference in viral susceptibility was not found between the two groups. This suggested that the low level of temephos resistance might not affect oral susceptibility. However, this needs further study.
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PMID:Potential development of temephos resistance in Aedes aegypti related to its mechanism and susceptibility to dengue virus. 1923 May 85


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