Raymond M

General

Full name : Raymond Michel

First name : Michel

Mail : Institut des Sciences de l'Evolution, Universite de Montpellier 11, 34095 Montpellier

Zip Code :

City :

Country : France

Email : raymond@isem.isem.univ-montp2.fr

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References (52)

Title : Biochemical Characterization of the Esterases Al and Bl Associated with Organophosphate Resistance in the Culex pipiens L. - Fournier_1987_Pestic.Biochem.Physiol_27_211
Author(s) : Fournier D , Bride JM , Mouches C , Raymond M , Magnin M , Berge JB , Pasteur N , Georghiou GP
Ref : Pestic Biochem Physiol , 27 :211 , 2015
Abstract : Two esterases, A1 and B1, displaying a high activity in organophosphate (OP) resistant Culex pipiens L. from southern France and in C. quinquefasciatus Say from California, respectively, have been analyzed. Both enzymes are shown to be soluble and to constitute a large proportion of the proteins (1-3% for esterase A1 and 6-12% for esterase B1). The size of native esterase A1 was estimated between 118 and 134 kDa, that of esterase B1 67 kDa. Upon SDS denaturation, esterase B1 leads a single polypeptide of 67 kDa which suggests that it is a monomeric protein; esterase A1 leads also a single polypeptide of 60 kDa suggesting a homodimeric structure of the protein. These observations are discussed with regards to esterase E4 of Myzus persicae Sultz.
ESTHER : Fournier_1987_Pestic.Biochem.Physiol_27_211
PubMedSearch : Fournier_1987_Pestic.Biochem.Physiol_27_211
PubMedID:

Title : Two single mutations commonly cause qualitative change of nonspecific carboxylesterases in insects - Cui_2011_Insect.Biochem.Mol.Biol_41_1
Author(s) : Cui F , Lin Z , Wang H , Liu S , Chang H , Reeck G , Qiao C , Raymond M , Kang L
Ref : Insect Biochemistry & Molecular Biology , 41 :1 , 2011
Abstract : Carboxylesterases provide key mechanisms of resistance to insecticides, particularly organophosphates (OPs), in insects. One resistance mechanism is a qualitative change in the properties of a carboxylesterase. Two mutant forms, G151D and W271L, have been observed, mostly in dipteran species, to affect substrate specificity of enzymes. But whether these two single mutations can commonly change character of insect carboxylesterases is unknown. In our study carboxylesterase genes from seven insects distributed among four orders were cloned, mutated at position 151 or 271 and expressed in Escherichia coli. The kinetics of the purified recombinant proteins was examined towards an artificial carboxylester and two OP insecticides. The G/A151D and W271L mutation significantly reduced carboxylesterase activity in 87.5% and 100% cases, respectively, and at the same time conferred OP hydrolase activities in 62.5% and 87.5% cases, respectively. Thus, the change at position 271 is more effective to influence substrate specificity than that at position 151. These results may suggest that these two mutations have the potential to cause insecticide resistance broadly in insects.
ESTHER : Cui_2011_Insect.Biochem.Mol.Biol_41_1
PubMedSearch : Cui_2011_Insect.Biochem.Mol.Biol_41_1
PubMedID: 20888910
Gene_locus related to this paper: aphgo-cxest

Title : Genetic differentiation of Culex pipiens (Diptera: Culicidae) in China - Cui_2007_Bull.Entomol.Res_97_291
Author(s) : Cui F , Qiao CL , Shen BC , Marquine M , Weill M , Raymond M
Ref : Bull Entomol Res , 97 :291 , 2007
Abstract : The population genetic structures of Culex pipiens Linnaeus were evaluated in China over a 2000 km transect that encompasses the two subspecies, C. p. pallens and C. p. quinquefasciatus. Four polymorphic allozyme loci were investigated in 1376 mosquitoes sampled from 20 populations across four provinces. These loci were not statistically dependent with no apparent heterozygote deficit or excess. On a regional scale (intra-province), a low (Fst=0.007-0.016) and significant genetic differentiation was found, with no clear geographical pattern. On a wider scale (inter-province), the genetic differentiation was higher (Fst=0.059), and an isolation by distance emerged. The results are compared with previous population genetic surveys of this mosquito species in different geographic areas over the world. The overall pattern suggests that Culex pipiens requires considerable distance (500-1000 km) to show isolation by distance, irrespective of the subspecies (C. p. pipiens, C. p. quinquefasciatus and C. p. pallens) or the geographic location.
ESTHER : Cui_2007_Bull.Entomol.Res_97_291
PubMedSearch : Cui_2007_Bull.Entomol.Res_97_291
PubMedID: 17524160

Title : Characterization of insensitive acetylcholinesterase (ace-1R) in Anopheles gambiae (Diptera: Culicidae): resistance levels and dominance - Djogbenou_2007_J.Med.Entomol_44_805
Author(s) : Djogbenou L , Weill M , Hougard JM , Raymond M , Akogbeto M , Chandre F
Ref : Journal of Medical Entomology , 44 :805 , 2007
Abstract : Characterization of insecticide resistance provides data on the evolutionary processes involved in the adaptation of insects to environmental changes. Studying the dominance status and resistance level represents a great interest, in terms of understanding resistance evolution in the field to eventually adapt vector control. Resistance and dominance levels conferred by the G119S mutation of acetylcholinesterase (ace-1R) of the mosquito Anopheles gambiae s.s. (Diptera: Culicidae) were studied for various insecticides belonging to different classes, using strains sharing the same genetic background. Our survey shows that the homozygote resistant strain AcerKis displayed a very high resistance level to various carbamates (range 3,000- to 5,000-fold) compared with that of various organophosphates (range 12- to 30-fold). Furthermore, the dominance status varied between semi-recessivity with fenitrothion and chlorpyrifos methyl insecticides to semidominance with temephos, carbosulfan, and propoxur. These results indicate that this resistance mechanism could spread rapidly in the field and then compromise the use of organophosphate and carbamate compounds in public health. This study underlines the necessity to monitor the ace-1R mutation in natural populations before planning and implementing malaria control programs based on the use of these insecticides.
ESTHER : Djogbenou_2007_J.Med.Entomol_44_805
PubMedSearch : Djogbenou_2007_J.Med.Entomol_44_805
PubMedID: 17915512
Gene_locus related to this paper: anoga-ACHE1

Title : Independent duplications of the acetylcholinesterase gene conferring insecticide resistance in the mosquito Culex pipiens - Labbe_2007_Mol.Biol.Evol_24_1056
Author(s) : Labbe P , Berthomieu A , Berticat C , Alout H , Raymond M , Lenormand T , Weill M
Ref : Molecular Biology Evolution , 24 :1056 , 2007
Abstract : Gene duplication is thought to be the main potential source of material for the evolution of new gene functions. Several models have been proposed for the evolution of new functions through duplication, most based on ancient events (Myr). We provide molecular evidence for the occurrence of several (at least 3) independent duplications of the ace-1 locus in the mosquito Culex pipiens, selected in response to insecticide pressure that probably occurred very recently (<40 years ago). This locus encodes the main target of several insecticides, the acetylcholinesterase. The duplications described consist of 2 alleles of ace-1, 1 susceptible and 1 resistant to insecticide, located on the same chromosome. These events were detected in different parts of the world and probably resulted from distinct mechanisms. We propose that duplications were selected because they reduce the fitness cost associated with the resistant ace-1 allele through the generation of persistent, advantageous heterozygosis. The rate of duplication of ace-1 in C. pipiens is probably underestimated, but seems to be rather high.
ESTHER : Labbe_2007_Mol.Biol.Evol_24_1056
PubMedSearch : Labbe_2007_Mol.Biol.Evol_24_1056
PubMedID: 17283366
Gene_locus related to this paper: culpi-ACHE1 , culqu-ACHE1

Title : Characterization of novel esterases in insecticide-resistant mosquitoes - Cui_2007_Insect.Biochem.Mol.Biol_37_1131
Author(s) : Cui F , Weill M , Berthomieu A , Raymond M , Qiao CL
Ref : Insect Biochemistry & Molecular Biology , 37 :1131 , 2007
Abstract : In the mosquito Culex pipiens complex (Diptera: Culicidae), the amplification of carboxylesterase genes is an important mechanism providing resistance to organophosphate insecticides. Various amplified alleles at the Ester locus have been identified over the world. In this study, two newly detected Ester alleles, Ester(B10) and Ester(11) (including associated Ester(A11) and Ester(B11)), coding for esterases B10 and A11-B11, respectively, are characterized qualitatively and quantitatively. A high molecular identity is observed both at the nucleotide level and at the deduced amino acid level among the known Ester alleles. Real-time quantitative PCR results suggest 2.5-fold amplification of the Ester(B10) allele, 36.5-fold amplification of the Ester(A11) allele, and 19.1-fold amplification of the Ester(B11) allele. The ca. 2-fold difference in amplification level between Ester(A11) and Ester(B11) may indicate a new model for the esterase amplification. Bioassays show that these two resistant Ester alleles only can confer moderate or low resistance to the tested organophosphate insecticides.
ESTHER : Cui_2007_Insect.Biochem.Mol.Biol_37_1131
PubMedSearch : Cui_2007_Insect.Biochem.Mol.Biol_37_1131
PubMedID: 17916499
Gene_locus related to this paper: culpi-ESTA , culqu-1estb

Title : Recent emergence of insensitive acetylcholinesterase in Chinese populations of the mosquito Culex pipiens (Diptera: Culicidae) - Cui_2006_J.Med.Entomol_43_878
Author(s) : Cui F , Raymond M , Berthomieu A , Alout H , Weill M , Qiao CL
Ref : Journal of Medical Entomology , 43 :878 , 2006
Abstract : Organophosphate/carbamate target resistance has emerged in Culex pipiens L. (Diptera: Culicidae), the vector of Wuchereria bancrofti and West Nile virus (family Flaviviridae, genus Flavivirus) in China. The insensitive acetylcholinesterase was detected in only one of 20 samples collected on a north-to-south transect. According to previous findings, a unique mutation, G119S in the ace-1 gene, explained this high insensitivity. Phylogenetic analysis indicates that the mutation G119S recently detected in China results from an independent mutation event. The G119S mutation thus occurred at least three times independently within the Cx. pipiens complex, once in the temperate (Cx. p. pipiens) and twice in the tropical form (Cx. p. quinquefasciatus). Bioassays performed with a purified G119S strain indicated that this substitution was associated with high levels of resistance to chlorpyrifos, fenitrothion, malathion, and parathion, but low levels of resistance to dichlorvos, trichlorfon, and fenthion. Hence, it is possible that in China, dichlorvos, trichlorfon, and fenthion will still achieve effective control even in the presence of the G119S mutation.
ESTHER : Cui_2006_J.Med.Entomol_43_878
PubMedSearch : Cui_2006_J.Med.Entomol_43_878
PubMedID: 17017223
Gene_locus related to this paper: culpi-ACHE1

Title : High Wolbachia density correlates with cost of infection for insecticide resistant Culex pipiens mosquitoes - Duron_2006_Evolution_60_303
Author(s) : Duron O , Labbe P , Berticat C , Rousset F , Guillot S , Raymond M , Weill M
Ref : Evolution , 60 :303 , 2006
Abstract : In the mosquito Culex pipiens, insecticide resistance genes alter many life-history traits and incur a fitness cost. Resistance to organophosphate insecticides involves two loci, with each locus coding for a different mechanism of resistance (degradation vs. insensitivity to insecticides). The density of intracellular Wolbachia bacteria has been found to be higher in resistant mosquitoes, regardless of the mechanism involved. To discriminate between costs of resistance due to resistance genes from those associated with elevated Wolbachia densities, we compared strains of mosquito sharing the same genetic background but differing in their resistance alleles and Wolbachia infection status. Life-history traits measured included strength of insecticide resistance, larval mortality, adult female size, fecundity, predation avoidance, mating competition, and strength of cytoplasmic incompatibility (CI). We found that: (1) when Wolbachia are removed, insecticide resistance genes still affect some life-history traits; (2) Wolbachia are capable of modifying the cost of resistance; (3) the cost of Wolbachia infections increases with their density; (4) different interactions occurred depending on the resistance alleles involved; and (5) high densities of Wolbachia do not increase the strength of CI or maternal transmission efficiency relative to low Wolbachia densities. Insecticide resistance genes generated variation in the costs of Wolbachia infections and provided an interesting opportunity to study how these costs evolve, a process generally operating when Wolbachia colonizes a new host.
ESTHER : Duron_2006_Evolution_60_303
PubMedSearch : Duron_2006_Evolution_60_303
PubMedID: 16610322

Title : Acetylcholinesterase genes within the Diptera: takeover and loss in true flies - Huchard_2006_Proc.Biol.Sci_273_2595
Author(s) : Huchard E , Martinez M , Alout H , Douzery EJ , Lutfalla G , Berthomieu A , Berticat C , Raymond M , Weill M
Ref : Proc Biol Sci , 273 :2595 , 2006
Abstract : It has recently been reported that the synaptic acetylcholinesterase (AChE) in mosquitoes is encoded by the ace-1 gene, distinct and divergent from the ace-2 gene, which performs this function in Drosophila. This is an unprecedented situation within the Diptera order because both ace genes derive from an old duplication and are present in most insects and arthropods. Nevertheless, Drosophila possesses only the ace-2 gene. Thus, a secondary loss occurred during the evolution of Diptera, implying a vital function switch from one gene (ace-1) to the other (ace-2). We sampled 78 species, representing 50 families (27% of the Dipteran families) spread over all major subdivisions of the Diptera, and looked for ace-1 and ace-2 by systematic PCR screening to determine which taxonomic groups within the Diptera have this gene change. We show that this loss probably extends to all true flies (or Cyclorrhapha), a large monophyletic group of the Diptera. We also show that ace-2 plays a non-detectable role in the synaptic AChE in a lower Diptera species, suggesting that it has non-synaptic functions. A relative molecular evolution rate test showed that the intensity of purifying selection on ace-2 sequences is constant across the Diptera, irrespective of the presence or absence of ace-1, confirming the evolutionary importance of non-synaptic functions for this gene. We discuss the evolutionary scenarios for the takeover of ace-2 and the loss of ace-1, taking into account our limited knowledge of non-synaptic functions of ace genes and some specific adaptations of true flies.
ESTHER : Huchard_2006_Proc.Biol.Sci_273_2595
PubMedSearch : Huchard_2006_Proc.Biol.Sci_273_2595
PubMedID: 17002944
Gene_locus related to this paper: culpi-ACHE1 , culpi-ACHE2 , drobs-ACHE2 , drosi-ACHE , drowi-ACHE , gloff-ACHE2

Title : Insecticide resistance: a silent base prediction -
Author(s) : Weill M , Berthomieu A , Berticat C , Lutfalla G , Negre V , Pasteur N , Philips A , Leonetti JP , Fort P , Raymond M
Ref : Current Biology , 14 :R552 , 2004
PubMedID: 15268871

Title : The unique mutation in ace-1 giving high insecticide resistance is easily detectable in mosquito vectors - Weill_2004_Insect.Mol.Biol_13_1
Author(s) : Weill M , Malcolm C , Chandre F , Mogensen K , Berthomieu A , Marquine M , Raymond M
Ref : Insect Molecular Biology , 13 :1 , 2004
Abstract : High insecticide resistance resulting from insensitive acetylcholinesterase (AChE) has emerged in mosquitoes. A single mutation (G119S of the ace-1 gene) explains this high resistance in Culex pipiens and in Anopheles gambiae. In order to provide better documentation of the ace-1 gene and the effect of the G119S mutation, we present a three-dimension structure model of AChE, showing that this unique substitution is localized in the oxyanion hole, explaining the insecticide insensitivity and its interference with the enzyme catalytic functions. As the G119S creates a restriction site, a simple PCR test was devised to detect its presence in both A. gambiae and C. pipiens, two mosquito species belonging to different subfamilies (Culicinae and Anophelinae). It is possibile that this mutation also explains the high resistance found in other mosquitoes, and the present results indicate that the PCR test detects the G119S mutation in the malaria vector A. albimanus. The G119S has thus occurred independently at least four times in mosquitoes and this PCR test is probably of broad applicability within the Culicidae family.
ESTHER : Weill_2004_Insect.Mol.Biol_13_1
PubMedSearch : Weill_2004_Insect.Mol.Biol_13_1
PubMedID: 14728661
Gene_locus related to this paper: anoga-ACHE1 , culpi-ACHE1

Title : Fitness costs of insecticide resistance in natural breeding sites of the mosquito Culex pipiens - Bourguet_2004_Evolution_58_128
Author(s) : Bourguet D , Guillemaud T , Chevillon C , Raymond M
Ref : Evolution , 58 :128 , 2004
Abstract : Genetic changes conferring adaptation to a new environment may induce a fitness cost in the previous environment. Although this prediction has been verified in laboratory conditions, few studies have tried to document this cost directly in natural populations. Here, we evaluated the pleiotropic effects of insecticide resistance on putative fitness components of the mosquito Culex pipiens. Experiments using different larval densities were performed during the summer in two natural breeding sites. Two loci that possess alleles conferring organophosphate (OP) resistance were considered: ace-1 coding for an acetylcholinesterase (AChE1, the OP target) and Ester, a ''super locus" including two closely linked loci coding for esterases A and B. Resistance ace-1 alleles coding for a modified AChE1 were associated with a longer development time and shorter wing length. The pleiotropic effects of two resistance alleles Ester1 and Ester4 coding for the overproduced esterases A1 and A4-B4, respectively, were more variable. Both A1 and A4-B4 reduced wing length, although only A1 was associated with a longer preimaginal stage. The fluctuating asymmetry (FA) of the wing did not respond to the presence or to the interaction of resistance alleles at the two loci at any of the density levels tested. Conversely, the FA of one wing section decreased when larval density increased. This may be the consequence of selection against less developmentally stable individuals. The results are discussed in relation to the local evolution of insecticide resistance genes.
ESTHER : Bourguet_2004_Evolution_58_128
PubMedSearch : Bourguet_2004_Evolution_58_128
PubMedID: 15058725

Title : Efficacy of insecticide mixtures against larvae of Culex quinquefasciatus (Say) (Diptera: Culicidae) resistant to pyrethroids and carbamates - Corbel_2004_Pest.Manag.Sci_60_375
Author(s) : Corbel V , Raymond M , Chandre F , Darriet F , Hougard JM
Ref : Pest Manag Sci , 60 :375 , 2004
Abstract : The efficacy of insecticide mixtures of permethrin (pyrethroid) and propoxur (carbamate) was tested by larval bioassays on two strains of Culex quinquefasciatus (Say), one resistant to pyrethroids and the other resistant to carbamates. The method consisted in combining one insecticide at the highest concentration causing no mortality (LC0) with increasing concentrations of the second one. The concentration-mortality regression lines were determined for permethrin and propoxur alone and in combination, and synergism ratios (SR) were calculated in order to determine the magnitude of an increase or decrease in efficacy with use of the mixtures. With the pyrethroid-resistant strain (BK-PER), the results showed that propoxur at LC0 significantly enhanced the insecticidal activity of permethrin (SR50 = 1.54), especially on the upper range of the concentration-mortality regression. Conversely, when permethrin at LC0 was tested with propoxur against the carbamate resistant strain (R-LAB), an antagonistic effect was observed (SR50 = 0.67). With the BK-PER strain, an increased oxidative detoxification (MFO) appeared to be the main mechanism responsible for the synergistic interaction. Nevertheless, antagonism in the R-LAB strain is probably due to a physiological perturbation implying different target sites for pyrethroid (ie sodium channel) and carbamate insecticides [ie acetylcholinesterase (EC 3.3.3.7) and choline acetyltransferase (EC 2.3.1.6)].
ESTHER : Corbel_2004_Pest.Manag.Sci_60_375
PubMedSearch : Corbel_2004_Pest.Manag.Sci_60_375
PubMedID: 15119600

Title : Insecticide resistance genes confer a predation cost on mosquitoes, Culex pipiens - Berticat_2004_Genet.Res_83_189
Author(s) : Berticat C , Duron O , Heyse D , Raymond M
Ref : Genetical Research , 83 :189 , 2004
Abstract : Newly occurring adaptive genes, such as those providing insecticide resistance, display a fitness cost which is poorly understood. In order to detect subtle behavioural changes induced by the presence of resistance genes, we used natural predators and compared their differential predation on susceptible and resistant Culex pipiens mosquitoes, using strains with a similar genetic background. Resistance genes were either coding an overproduced detoxifying esterase (locus Ester), or an insensitive target (locus ace-1). Differential predation was measured between susceptible and resistant individuals, as well as among resistant mosquitoes. A backswimmer, a water measurer, a water boatman and a predaceous diving beetle were used as larval predators, and a pholcid spider as adult predator. Overall, the presence of a resistance gene increased the probability of predation: all resistance genes displayed predation costs relative to susceptible ones, at either the larval or adult stage, or both. Interestingly, predation preferences among the susceptible and the resistance genes were not ranked uniformly. Possible explanations for these results are given, and we suggest that predators, which are designed by natural selection to detect specific behavioural phenotypes, are useful tools to explore non-obvious differences between two classes of individuals, for example when they differ by the presence or absence of one recent gene, such as insecticide resistance genes.
ESTHER : Berticat_2004_Genet.Res_83_189
PubMedSearch : Berticat_2004_Genet.Res_83_189
PubMedID: 15462412

Title : Poster (28) Two genes code for acetylcholinesterase in insects. -
Author(s) : Raymond M
Ref : In: Cholinesterases in the Second Millennium: Biomolecular and Pathological Aspects , (Inestrosa NC, Campos EO) P. Universidad Catolica de Chile-FONDAP Biomedicina :335 , 2004
PubMedID:

Title : [Insecticide resistance in the mosquito Culex pipiens] -
Author(s) : Weill M , Duron O , Labbe P , Berthomieu A , Raymond M
Ref : Med Sci (Paris) , 19 :1190 , 2003
PubMedID: 14691742

Title : Comparative genomics: Insecticide resistance in mosquito vectors - Weill_2003_Nature_423_136
Author(s) : Weill M , Lutfalla G , Mogensen K , Chandre F , Berthomieu A , Berticat C , Pasteur N , Philips A , Fort P , Raymond M
Ref : Nature , 423 :136 , 2003
Abstract : Resistance to insecticides among mosquitoes that act as vectors for malaria (Anopheles gambiae) and West Nile virus (Culex pipiens) emerged more than 25 years ago in Africa, America and Europe; this resistance is frequently due to a loss of sensitivity of the insect's acetylcholinesterase enzyme to organophosphates and carbamates1. Here we show that this insensitivity results from a single amino-acid substitution in the enzyme, which we found in ten highly resistant strains of C. pipiens from tropical (Africa and Caribbean) and temperate (Europe) areas, as well as in one resistant African strain of A. gambiae. Our identification of this mutation may pave the way for designing new insecticides.
ESTHER : Weill_2003_Nature_423_136
PubMedSearch : Weill_2003_Nature_423_136
PubMedID: 12736674
Gene_locus related to this paper: anoga-ACHE1 , culpi-ACHE1

Title : High Wolbachia density in insecticide-resistant mosquitoes - Berticat_2002_Proc.Biol.Sci_269_1413
Author(s) : Berticat C , Rousset F , Raymond M , Berthomieu A , Weill M
Ref : Proc Biol Sci , 269 :1413 , 2002
Abstract : Wolbachia symbionts are responsible for various alterations in host reproduction. The effects of the host genome on endosymbiont levels have often been suggested, but rarely described. Here, we show that Wolbachia density is strongly modified by the presence of insecticide-resistant genes in the common house mosquito, Culex pipiens. The Wolbachia density was estimated using a real-time quantitative PCR assay. Strains harbouring different genes conferring resistance were more infected than a susceptible strain with the same genetic background. We show that this interaction also operates in natural populations. We propose that mosquitoes may control Wolbachia density less efficiently when they carry an insecticide-resistant gene, i.e. when they suffer from a physiological resistance cost.
ESTHER : Berticat_2002_Proc.Biol.Sci_269_1413
PubMedSearch : Berticat_2002_Proc.Biol.Sci_269_1413
PubMedID: 12079666

Title : A novel acetylcholinesterase gene in mosquitoes codes for the insecticide target and is non-homologous to the ace gene Drosophila - Weill_2002_Proc.R.Soc.Lond.B.Biol.Sci_269_2007
Author(s) : Weill M , Fort P , Berthomieu A , Dubois MP , Pasteur N , Raymond M
Ref : Proc R Soc Lond B Biol Sci , 269 :2007 , 2002
Abstract : Acetylcholinesterase (AChE) is the target of two major insecticide families, organophosphates (OPs) and carbamates. AChE insensitivity is a frequent resistance mechanism in insects and responsible mutations in the ace gene were identified in two Diptera, Drosophila melanogaster and Musca domestica. However, for other insects, the ace gene cloned by homology with Drosophila does not code for the insensitive AChE in resistant individuals, indicating the existence of a second ace locus. We identified two AChE loci in the genome of Anopheles gambiae, one (ace-1) being a new locus and the other (ace-2) being homologous to the gene previously described in Drosophila. The gene ace-1 has no obvious homologue in the Drosophila genome and was found in 15 mosquito species investigated. In An. gambiae, ace-1 and ace-2 display 53% similarity at the amino acid level and an overall phylogeny indicates that they probably diverged before the differentiation of insects. Thus, both genes are likely to be present in the majority of insects and the absence of ace-1 in Drosophila is probably due to a secondary loss. In one mosquito (Culex pipiens), ace-1 was found to be tightly linked with insecticide resistance and probably encodes the AChE OP target. These results have important implications for the design of new insecticides, as the target AChE is thus encoded by distinct genes in different insect groups, even within the Diptera: ace-2 in at least the Drosophilidae and Muscidae and ace-1 in at least the Culicidae. Evolutionary scenarios leading to such a peculiar situation are discussed.
ESTHER : Weill_2002_Proc.R.Soc.Lond.B.Biol.Sci_269_2007
PubMedSearch : Weill_2002_Proc.R.Soc.Lond.B.Biol.Sci_269_2007
PubMedID: 12396499
Gene_locus related to this paper: aedae-ACHE1 , anoga-ACHE1 , anoga-ACHE2 , cioin-ACHE1 , ciosa-ACHE , culpi-ACHE1

Title : Recombination between two amplified esterase alleles in Culex pipiens - Berticat_2001_J.Hered_92_349
Author(s) : Berticat C , Marquine M , Raymond M , Chevillon C
Ref : Journal of Heredity , 92 :349 , 2001
Abstract : Esterase gene amplification at the Ester superlocus provides organophosphate resistance in the mosquito Culex pipiens (L.). In this study we explored the possibility of recombination between two amplified esterase alleles, thus generating a composite amplified allele. To do that, females heterozygous for two distinct amplified alleles (Ester(2) and Ester(4)) were crossed with males homozygous for a third resistance allele (Ester(8)). Among analyzed offspring, one recombinant composite allele (Ester(2-4)) was detected, providing a rate of recombination of approximately 0.2%. This is the first report of a recombination between two distinct amplified esterase alleles. This phenomenon renders the predictability of allele evolution considerably more complex than was previously thought.
ESTHER : Berticat_2001_J.Hered_92_349
PubMedSearch : Berticat_2001_J.Hered_92_349
PubMedID: 11535649

Title : Identification and characterization of novel organophosphate detoxifying esterase alleles in the Guangzhou area of China - Weill_2001_J.Am.Mosq.Control.Assoc_17_238
Author(s) : Weill M , Marquine M , Berthomieu A , Dubois MP , Bernard C , Qiao CL , Raymond M
Ref : J Am Mosq Control Assoc , 17 :238 , 2001
Abstract : In the mosquito Culex pipiens various alleles at the Ester locus provide insecticide resistance These resistance alleles display a heterogeneous geographical distribution particularly in China where they are highly diverse A new resistance allele Ester9 coding for the overproduced esterases A9 and B9 is characterized and compared to the known resistant allele Ester8 isolated from the same southern China sample from Guangzhou Both alleles provide low but significant resistance to chlorpyrifos relative synergism ratio RSR 3 and temephos RSR 1.4 which is consistent with the low level of gene amplification they display 15 copies for Ester9 and 4 copies for Ester8 The full genomic sequence of the allele coding A8 and A9 is presented which allowed us to set up a polymerase chain reaction assay to specifically identify these alleles The peculiar situation in southern China where numerous resistance alleles coexist is discussed in comparison with the Mediterranean situation the only one with a similar diversity of overproduced esterases
ESTHER : Weill_2001_J.Am.Mosq.Control.Assoc_17_238
PubMedSearch : Weill_2001_J.Am.Mosq.Control.Assoc_17_238
PubMedID: 11804460
Gene_locus related to this paper: culqu-2estb

Title : Insecticide resistance in the mosquito culex pipiens: what have we learned about adaptation? - Raymond_2001_Genetica_112-113_287
Author(s) : Raymond M , Berticat C , Weill M , Pasteur N , Chevillon C
Ref : Genetica , 112-113 :287 , 2001
Abstract : Resistance to organophosphate (OP) insecticide in the mosquito Culex pipiens has been studied for ca. 30 years. This example of micro-evolution has been thoroughly investigated as an opportunity to assess precisely both the new adapted phenotypes and the associated genetic changes. A notable feature is that OP resistance is achieved with few genes, and these genes have generally large effects. The molecular events generating such resistance genes are complex (e.g., gene amplification, gene regulation) potentially explaining their low frequency of de novo occurrence. In contrast, migration is a frequent event, including passive transportation between distant populations. This generates a complex interaction between mutations and migration, and promotes competition among resistance alleles. When the precise physiological action of each gene product is rather well known, it is possible to understand the dominance level or the type of epistasis observed. It is however difficult to predict a priori how resistance genes will interact, and it is too early to state whether or not this will be ever possible. These resistance genes are costly, and the cost is variable among them. It is usually believed that the initial fitness cost would gradually decrease due to subsequent mutations with a modifier effect. In the present example, a particular modifier occurred (a gene duplication) at one resistance locus, whereas at the other one reduction of cost is driven by allele replacement and apparently not by selection of modifiers.
ESTHER : Raymond_2001_Genetica_112-113_287
PubMedSearch : Raymond_2001_Genetica_112-113_287
PubMedID: 11838771

Title : Quantitative polymerase chain reaction to estimate the number of amplified esterase genes in insecticide-resistant mosquitoes -
Author(s) : Weill M , Berticat C , Raymond M , Chevillon C
Ref : Analytical Biochemistry , 285 :267 , 2000
PubMedID: 11017713

Title : The kdr mutation occurs in the Mopti form of Anopheles gambiae s.s. through introgression - Weill_2000_Insect.Mol.Biol_9_451
Author(s) : Weill M , Chandre F , Brengues C , Manguin S , Akogbeto M , Pasteur N , Guillet P , Raymond M
Ref : Insect Molecular Biology , 9 :451 , 2000
Abstract : Anopheles gambiae s.s. is a complex of sibling taxa characterized by various paracentric inversions. In west and central Africa, where several taxa are sympatric, a kdr mutation responsible for pyrethroid resistance has been described in only one (the S taxon), suggesting an absence of gene flow between them. Following a thorough sampling, we have found a kdr mutation in another taxon (M). To establish whether this mutation is the same event or not, the large intron upstream of the kdr mutation was sequenced to find polymorphic sites in susceptible/resistant and M/S mosquitoes. The low genetic diversity found in this DNA region indicates that a local genetic sweep has recently occurred. However, some polymorphic sites were found, and it is therefore concluded that the kdr mutation in the M taxon is not an independent mutation event, and is best explained by an introgression from the S taxon. These results are discussed within the context of possible gene flow between members of An. gambiae s.s. taxa, and with the possible spread of the kdr mutation in other closely related malaria vectors of the An. gambiae complex.
ESTHER : Weill_2000_Insect.Mol.Biol_9_451
PubMedSearch : Weill_2000_Insect.Mol.Biol_9_451
PubMedID: 11029663

Title : Tracking the evolution of insecticide resistance in the mosquito Culex pipiens - Lenormand_1999_Nature_400_861
Author(s) : Lenormand T , Bourguet D , Guillemaud T , Raymond M
Ref : Nature , 400 :861 , 1999
Abstract : The evolution of pesticide resistance provides some of the most striking examples of darwinian evolution occurring over a human life span. Identification of resistance alleles opens an outstanding framework in which to study the evolution of adaptive mutations from the beginning of pesticide application, the evolution of interactions between alleles (dominance) or between loci (epistasis). Here we show that resistance alleles can also be used as markers to dissect population processes at a microevolutionary scale. We have focused on the antagonistic roles of selection and migration involved in the dynamics of local adaptation with reference to allelic frequencies at two resistance loci in the mosquito Culex pipiens. We find that their frequencies follow an annual cycle of large amplitude (25%), and we precisely unravel the seasonal variation of migration and selection underlying this cycle. Our results provide a firm basis on which to devise an insecticide treatment strategy that will better control the evolution of resistance genes and the growth of mosquito populations.
ESTHER : Lenormand_1999_Nature_400_861
PubMedSearch : Lenormand_1999_Nature_400_861
PubMedID: 10476962

Title : A new esterase gene amplification involved in OP resistance in Culex pipiens mosquitoes from China - Qiao_1998_Biochem.Genet_36_417
Author(s) : Qiao CL , Marquine M , Pasteur N , Raymond M
Ref : Biochemical Genetics , 36 :417 , 1998
Abstract : Two overproduced esterases (A8 and B8) not previously described were found in southern China. They provide a low resistance level to organophosphate (OP) insecticides, and correspond to a coamplification of both esterase loci (Est-2 and Est-3) classically involved in OP resistance for this mosquito species. This coamplification is distinct from all other similar events thus far reported. The peculiar situation in southern China, where numerous OP resistance alleles at these two loci were found, is discussed in comparison with the Mediterranean situation, the only one with a similar diversity of overproduced esterases.
ESTHER : Qiao_1998_Biochem.Genet_36_417
PubMedSearch : Qiao_1998_Biochem.Genet_36_417
PubMedID: 10230522

Title : Appearance and sweep of a gene duplication: adaptative response and potential for new functions in the mosquito culex pipiens - Lenormand_1998_Evolution_52_1705
Author(s) : Lenormand T , Guillemaud T , Bourguet D , Raymond M
Ref : Evolution , 52 :1705 , 1998
Abstract : Evolution of a new gene function is a fundamental process of adaptation. Gene duplication followed by divergence due to relaxed selection on redundant copies has been viewed as the predominant mechanism involved in this process. At a macroevolutionary scale, evidence for this scenario came from the analysis of sequences of genes families. However, even if several genetic models have described the different potential microevolutionary scenario for a new function to evolve, little is really known about the initial evolutionary dynamics of such processes. We analyze such early dynamics in natural populations of the mosquito Culex pipiens polymorphic for a duplication at Ace.1, a locus involved in insecticide resistance. The date of occurrence and the selective advantages of the duplication were estimated using frequency data. We propose a scenario where the spread of a duplication is driven, from the very beginning, by selection due to insecticide treatment.
ESTHER : Lenormand_1998_Evolution_52_1705
PubMedSearch : Lenormand_1998_Evolution_52_1705
PubMedID: 28565319

Title : The acetylcholinesterase gene Ace: a diagnostic marker for the Pipiens and Quinquefasciatus forms of the Culex pipiens complex - Bourguet_1998_J.Am.Mosq.Control.Assoc_14_390
Author(s) : Bourguet D , Fonseca D , Vourch G , Dubois MP , Chandre F , Severini C , Raymond M
Ref : J Am Mosq Control Assoc , 14 :390 , 1998
Abstract : The taxonomy of the Culex pipiens complex remains a controversial issue in mosquito systematics. Based on morphologic characters, 2 allopatric taxa are recognized, namely Cx. pipiens (including the form "molestus") in temperate areas and Cx. quinquefasciatus in tropical areas. Here we report on variability at the nucleotide level of an acetylcholinesterase gene in several strains and natural populations of this species complex. Few polymorphisms were found in coding regions within a subspecies but many polymorphisms were observed between subspecies in noncoding regions. We describe a method based on a restriction enzyme polymorphism in polymerase chain reaction-amplified DNA, in which the presence or absence of one restriction site discriminates Cx. pipiens, Cx. quinquefasciatus, and their hybrids. This technique reliably discriminates mosquitoes from more than 30 worldwide strains or populations. Polymerase chain reaction amplification of specific alleles may also be a useful tool for characterizing specific alleles of each sibling taxon.
ESTHER : Bourguet_1998_J.Am.Mosq.Control.Assoc_14_390
PubMedSearch : Bourguet_1998_J.Am.Mosq.Control.Assoc_14_390
PubMedID: 10084132

Title : Evaluating gene flow using selected markers: a case study - Lenormand_1998_Genetics_149_1383
Author(s) : Lenormand T , Guillemaud T , Bourguet D , Raymond M
Ref : Genetics , 149 :1383 , 1998
Abstract : The extent to which an organism is locally adapted in an environmental pocket depends on the selection intensities inside and outside the pocket, on migration, and on the size of the pocket. When two or more loci are involved in this local adaptation, measuring their frequency gradients and their linkage disequilbria allows one to disentangle the forces-migration and selection-acting on the system. We apply this method to the case of a local adaptation to organophosphate insecticides in the mosquito Culex pipiens pipiens in southern France. The study of two different resistance loci allowed us to estimate with support limits gene flow as well as selection pressure on insecticide resistance and the fitness costs associated with each locus. These estimates permit us to pinpoint the conditions for the maintenance of this pocket of adaptation as well as the effect of the interaction between the two resistance loci.
ESTHER : Lenormand_1998_Genetics_149_1383
PubMedSearch : Lenormand_1998_Genetics_149_1383
PubMedID: 9649528

Title : A sex-linked Ace gene, not linked to insensitive acetylcholinesterase- mediated insecticide resistance in Culex pipiens - Malcolm_1998_Insect.Mol.Biol_7_107
Author(s) : Malcolm CA , Bourguet D , Ascolillo A , Rooker SJ , Garvey CF , Hall LM , Pasteur N , Raymond M
Ref : Insect Molecular Biology , 7 :107 , 1998
Abstract : An acetylcholinesterase (AChE) gene, Ace.x, showing 93% identity of deduced amino acid sequence to Anopheles stephensi Ace has been cloned from a Culex pipiens strain homozygous for insensitive AChE (iAChE) mediated insecticide resistance. DNA sequence of genomic DNA clones identified exons 2-5. RFLP of six clones indicated four possible alleles. Linkage analysis located Ace.x to chromosome I, less than 0.8 centimorgans from the sex locus, whereas the locus conferring resistance was 2.0 centimorgans from plum-eye on chromosome II. Ace.1 coding for AChE1, which is associated with resistance, is therefore autosomal. We propose that Ace.x is the recently postulated Ace.2 coding for the biochemically distinct AChE2, which is not associated with resistance.
ESTHER : Malcolm_1998_Insect.Mol.Biol_7_107
PubMedSearch : Malcolm_1998_Insect.Mol.Biol_7_107
PubMedID: 9535157
Gene_locus related to this paper: culpi-ACHE2

Title : Polymorphisms and fluctuations in copy number of amplified esterase genes in Culex pipiens mosquitoes - Callaghan_1998_Insect.Mol.Biol_7_295
Author(s) : Callaghan A , Guillemaud T , Makate N , Raymond M
Ref : Insect Molecular Biology , 7 :295 , 1998
Abstract : In Culex pipiens mosquitoes, A2 esterase alleles are co-amplified with B2 esterase alleles in response to selection with organophosphate insecticides. In this study the amplified A2 and B2 sequences were compared between twelve strains from four continents by restriction mapping. The restriction maps were almost identical in each strain throughout 22 kb surrounding the genes, suggesting that this represents a constant core sequence. A polymorphism was found in two strains collected from Egypt and Kenya in the mid 1980s. This polymorphism was present in all copies of the amplicon, which suggests that a mechanism of sequence homogenization was operating, i.e. concerted evolution. These two strains were almost certainly descendants from the same population and migration probably occurred along the River Nile. Although the maps were almost identical in each strain, dot blotting demonstrated that amplification levels differed by up to 13-fold between strains. Thus the presence of the A2-B2 haplotype cannot be used to indicate the level of amplification or any particular degree of resistance.
ESTHER : Callaghan_1998_Insect.Mol.Biol_7_295
PubMedSearch : Callaghan_1998_Insect.Mol.Biol_7_295
PubMedID: 9662480

Title : Acetylcholinesterase and Insecticide Resistance in the Mosquito Culex Pipiens -
Author(s) : Bourguet D , Fournier D , Toutant JP , Arpagaus M , Raymond M
Ref : In: Structure and Function of Cholinesterases and Related Proteins - Proceedings of Sixth International Meeting on Cholinesterases , (Doctor, B.P., Taylor, P., Quinn, D.M., Rotundo, R.L., Gentry, M.K. Eds) Plenum Publishing Corp. :483 , 1998
PubMedID:

Title : Cross-resistance to pyrethroid and organophosphorus insecticides in the southern house mosquito (Diptera:Culicidae) from Cuba - Bisset_1997_J.Med.Entomol_34_244
Author(s) : Bisset J , Rodriguez M , Soca A , Pasteur N , Raymond M
Ref : Journal of Medical Entomology , 34 :244 , 1997
Abstract : A sample of the southern house mosquito, Culex pipiens quinquefasciatus Say, from Cuba was subjected to lambda-cyhalothrin selection to evaluate the usefulness of this pyrethroid insecticide for mosquito control. High resistance developed after 6 generations of selection. Little or no cross-resistance was observed to other pyrethroids (deltamethrin and cypermethrin), to a carbamate (propoxur) and to some organophosphates (chlorpyrifos and pirimiphos-methyl), but high cross-resistance was found to malathion (organophosphate). Possible resistance mechanisms responsible for this phenomenon are discussed.
ESTHER : Bisset_1997_J.Med.Entomol_34_244
PubMedSearch : Bisset_1997_J.Med.Entomol_34_244
PubMedID: 9103771

Title : Variation of dominance of newly arisen adaptive genes - Bourguet_1997_Genetics_147_1225
Author(s) : Bourguet D , Lenormand T , Guillemaud T , Marcel V , Fournier D , Raymond M
Ref : Genetics , 147 :1225 , 1997
Abstract : Newly arisen adaptive alleles such as insecticide resistance genes represent a good opportunity to investigate the theories put forth to explain the molecular basis of dominance and its possible evolution. Dominance levels of insecticide resistance conferred by insensitive alleles of the acetylcholinesterase gene were analyzed in five resistant strains of the mosquito Culex pipiens. Dominance levels were found to differ between strains, varying from partial recessivity to complete dominance. This variation was not explained by differences in catalytic properties of the enzyme, since four of the five resistant strains had identical inhibition properties for the insensitive acetylcholinesterase. Among these four laboratory strains and in individuals collected from natural populations, we found a correlation between increased acetylcholinesterase activities and higher dominance levels. We propose a molecular explanation for how variation in acetylcholinesterase activity may result in variation of dominance level. We also conjecture that the four resistant strains did not differ in their amino acid sequence in the catalytically active regions of acetylcholinesterase, but that the expression of the gene was regulated by either neighboring or distant sites, thereby modifying the dominance level. Under this interpretation, dominance levels may evolve in this system, since heritable variation in acetylcholinesterase activity was found.
ESTHER : Bourguet_1997_Genetics_147_1225
PubMedSearch : Bourguet_1997_Genetics_147_1225
PubMedID: 9383065

Title : Pleiotropy of adaptive changes in populations: comparisons among insecticide resistance genes in Culex pipiens - Chevillon_1997_Genet.Res_70_195
Author(s) : Chevillon C , Bourguet D , Rousset F , Pasteur N , Raymond M
Ref : Genetical Research , 70 :195 , 1997
Abstract : Resistance to toxicants is a convenient model for investigating whether adaptive changes are associated with pleiotropic fitness costs. Despite the voluminous literature devoted to this subject, intraspecific comparisons among toxicant resistance genes are rare. We report here results on the pleiotropic effect on adult survival of Culex pipiens mutants involved in the same adaptation: the resistance to organophosphorus insecticides. This field study was performed in southern France where four resistance genes sequentially appeared and increased in frequency in response to intense insecticide control. By repeated sampling of overwintering females through winter, we analysed the impact of each of three resistance genes on adult survival. We showed that (i) the most recent gene seems to be of no disadvantage during winter, (ii) the oldest affects survival in some environmental conditions, and (iii) the third induces a constant, severe and dominant survival cost. Such variability is discussed in relation to the physiological changes involved in resistance.
ESTHER : Chevillon_1997_Genet.Res_70_195
PubMedSearch : Chevillon_1997_Genet.Res_70_195
PubMedID: 9494436

Title : Insecticide resistance genes in mosquitoes: their mutations, migration, and selection in field populations. - Pasteur_1996_J.Hered_87_444
Author(s) : Pasteur N , Raymond M
Ref : Journal of Heredity , 87 :444 , 1996
Abstract : Insecticides have been used intensively to control insect populations over the last 50 years and many species of insects have developed resistance to several families of insecticides. These resistances are mainly due to two mechanisms: mutation of the insecticide target protein (leading to a decrease in its affinity for the concerned insecticide family), and increased detoxification. Recent molecular studies suggest that the mutations conferring resistance are rare and sometimes unique events in any given species. The wide geographic distribution of some of these genes can then only be explained by the balance between migration and selection at the population level.
ESTHER : Pasteur_1996_J.Hered_87_444
PubMedSearch : Pasteur_1996_J.Hered_87_444
PubMedID: 8981762

Title : An insensitive acetylcholinesterase in Culex pipiens (Diptera:Culicidae) from Portugal - Bourguet_1996_J.Econ.Entomol_89_1060
Author(s) : Bourguet D , Capela R , Raymond M
Ref : J Econ Entomol , 89 :1060 , 1996
Abstract : Resistance mechanisms of a strain (PRAIAS) of northern house mosquito, Culex pipiens L., collected in Portugal in 1993, and highly resistant to organophosphates and carbamates, were investigated by comparing the resistance characteristics to 3 organophosphorous (temephos, chlorpyrifos, malathion) and 1 carbamate (propoxur) insecticides in the presence or absence of synergists; and by determining the possible occurrence of overproduced esterases or insensitive acetylcholinesterase (AChE). The reference strain MSE from southern France, with an insensitive AChE, was included in all analyses for comparison. For organophosphorous insecticides, resistance in PRAIAS was caused by an insensitive AChE and an increase in oxidative metabolism, although the 2nd mechanism has only a marginal effect. For propoxur, the insensitive AChE was the only resistance mechanism detected. Biochemical properties of both the French and Portuguese insensitive AChEs were similar. We cannot exclude the possibility that PRAIAS and MSE strains possess exactly the same insensitive AChE allele.
ESTHER : Bourguet_1996_J.Econ.Entomol_89_1060
PubMedSearch : Bourguet_1996_J.Econ.Entomol_89_1060
PubMedID: 8913110

Title : Dominance of insecticide resistance presents a plastic response - Bourguet_1996_Genetics_143_407
Author(s) : Bourguet D , Prout M , Raymond M
Ref : Genetics , 143 :407 , 1996
Abstract : Dominance level of insecticide resistance provided by one major gene (an insensitive acetylcholinesterase) in the mosquito Culex pipiens was studied in two distinct environments. Dominance level was found to be very different environments, varying from almost complete dominance to almost recessive when either propoxur (a carbamate insecticide) or chlorpyrifos (an organophosphorus insecticide) was used. To better understand this plastic response, three environmental parameters were manipulated and their interactions studied. For chlorpyrifos, each parameter had a small effect, but when all parameters were changed, the dominance level was greatly affected. For propoxur, one environmental parameter had a large effect by itself. It was further studied to understand the causal relationship of this plasticity. Recessivity of resistance was associated with more demanding environments. These results are discussed in the context of the various theories of the evolution of dominance. It appears that dominance of insecticide resistance cannot be directly predicted by Wright's physiological theory.
ESTHER : Bourguet_1996_Genetics_143_407
PubMedSearch : Bourguet_1996_Genetics_143_407
PubMedID: 8722792

Title : Duplication of the Ace.1 locus in Culex pipiens mosquitoes from the Caribbean - Bourguet_1996_Biochem.Genet_34_351
Author(s) : Bourguet D , Raymond M , Bisset J , Pasteur N , Arpagaus M
Ref : Biochemical Genetics , 34 :351 , 1996
Abstract : In Culex pipiens mosquitoes, AChE1 encoded by the locus Ace.1 is the target of organophosphorus and carbamate insecticides. In several resistant strains homozygous for Ace.1RR, insensitive AChE1 is exclusively found. An unusual situation occurs in two Caribbean resistant strains where each mosquito, at each generation, displays a mixture of sensitive and insensitive AChE1. These mosquitoes are not heterozygotes, Ace.1RS, as preimaginal mortalities cannot account for the lethality of both homozygous classes. This situation is best explained by the existence of two Ace.1 loci, coding, respectively, a sensitive and an insensitive AChE1. Thus, we suggest that in the Caribbean a duplication of the Ace.1 locus occurred before the appearance of insecticide resistance at one of the two copies.
ESTHER : Bourguet_1996_Biochem.Genet_34_351
PubMedSearch : Bourguet_1996_Biochem.Genet_34_351
PubMedID: 8978907

Title : Coamplification of esterase A and B genes as a single unit in Culex pipiens misquitos - Rooker_1996_Heredity_77_555
Author(s) : Rooker S , Guillema T , Berge JB , Pasteur N , Raymond M
Ref : Heredity , 77 (5) :555 , 1996
Abstract : In Culex pipiens mosquitoes, resistance to organophosphorous insecticides often results from increased detoxification by two types of esterases, A and B, which are closely linked. Overproduction of all esterase B so far investigated (B1, B2, B4, B5 and B6) is from gene amplification. An esterase A gene (esterase A2) has recently been cloned from mosquitoes with the overproduced esterases A2 and B2, and amplification of this gene has also been reported. We describe the cDNA sequences of three additional esterase genes from insecticide-resistant strains of Culex pipiens originating from France and California which show at least 93 per cent homology with the esterase A2 gene sequence. Restriction enzyme mapping shows that the esterase A gene lies within 2.2 kb of the esterase B gene. In mosquitoes with overproduced esterases A2 and B2, the amplification level of esterase A is equal to that of esterase B suggesting that the genes are coamplified. Furthermore, we show that in one strain with an overproduced A esterase (A1), gene amplification cannot account for the increased protein level. This indicates that overproduction of esterases A can be achieved through two different mechanisms: gene amplification and a regulatory mechanism--the nature of which remains to be identified.
ESTHER : Rooker_1996_Heredity_77_555
PubMedSearch : Rooker_1996_Heredity_77_555
PubMedID: 8939022
Gene_locus related to this paper: culpi-ESTA

Title : Determination of Ace.1 Genotypes in Single Mosquitoes: Toward an Ecumenical Biochemical Test - Bourguet_1996_Pestic.Biochem.Physiol_55_122
Author(s) : Bourguet D , Pasteur N , Bisset J , Raymond M
Ref : Pestic Biochem Physiol , 55 :122 , 1996
Abstract : The occurrence of two acetylcholinesterases, AChE1 and AChE2, in the mosquito Culex pipiens has been recently documented. Resistance to organophosphates and carbamates due to target insensitivity is the result of a qualitative change of only AChE1, encoded by the Ace.1 gene. Because AChE1 and AChE2 differ in their sensitivity to inhibitors, Ace.1 genotypes can be misclassified by previous tests. We describe a new rapid microplate test that allows unambiguous identification of Ace.1 genotypes. This test involves comparing AChE activities in the absence of insecticide and in the presence of two propoxur concentrations: a low concentration that inhibits only the sensitive AChE1 and a higher concentration that inhibits also AChE2 but not the insensitive AChE1 responsible of insecticide resistance. This comparison allows the identification of the three Ace.1 genotypes: resistant (Ace.1RR), susceptible (Ace.1SS) homozygotes, and heterozygotes (Ace.1RS). The similarity of propoxur sensitivity of modified AChE1s found in various resistant strains from the United States, Europe, and Africa indicates that this test is probably suitable for all the Ace.1 alleles described so far in C. pipiens.
ESTHER : Bourguet_1996_Pestic.Biochem.Physiol_55_122
PubMedSearch : Bourguet_1996_Pestic.Biochem.Physiol_55_122
PubMedID: 8980036

Title : Existence of two acetylcholinesterases in the mosquito Culex pipiens (Diptera:Culicidae) - Bourguet_1996_J.Neurochem_67_2115
Author(s) : Bourguet D , Raymond M , Fournier D , Malcolm CA , Toutant JP , Arpagaus M
Ref : Journal of Neurochemistry , 67 :2115 , 1996
Abstract : Two acetylcholinesterases (AChEs), AChE1 and AChE2, differing in substrate specificity and in some aspects of inhibitor sensitivity, have been characterized in the mosquito Culex pipiens. The results of ultracentrifugation in sucrose gradients and nondenaturing gel electrophoresis of AChE activity peak fractions show that each AChE is present as two molecular forms: one amphiphilic dimer possessing a glycolipid anchor and one hydrophilic dimer that does not interact with nondenaturing detergents. Treatment by phosphatidylinositol-specific phospholipase C converts each type of amphiphilic dimer into the corresponding hydrophilic dimer. Molecular forms of AChE1 have a lower electrophoretic mobility than those of AChE2. However, amphiphilic dimers and hydrophilic dimers have similar sedimentation coefficients (5.5S and 6.5S, respectively). AChE1 and AChE2 dimers, amphiphilic or hydrophilic, resist dithiothreitol reduction under conditions that allow reduction of Drosophila AChE dimers. In the insecticide-susceptible strain S-LAB, AChE1 is inhibited by 5 x 10(-4) M propoxur (a carbamate insecticide), whereas AChE2 is resistant. All animals are killed by this concentration of propoxur, indicating that only AChE1 fulfills the physiological function of neurotransmitter hydrolysis at synapses. In the insecticide-resistant strain, MSE, there is no mortality after exposure to 5 x 10(-4) M propoxur: AChE2 sensitivity to propoxur is unchanged, whereas AChE1 is now resistant to 5 x 10(-4) M propoxur. The possibility that AChE1 and AChE2 are products of tissue-specific posttranslational modifications of a single gene is discussed, but we suggest, based on recent results obtained at the molecular level in mosquitoes, that they are encoded by two different genes.
ESTHER : Bourguet_1996_J.Neurochem_67_2115
PubMedSearch : Bourguet_1996_J.Neurochem_67_2115
PubMedID: 8863521

Title : Resistance to organophosphorous insecticides in Culex pipiens quinquefasciatus (Diptera: Culicidae) from Martinique - Yebakima_1995_J.Med.Entomol_32_77
Author(s) : Yebakima A , Raymond M , Marquine M , Pasteur N
Ref : Journal of Medical Entomology , 32 :77 , 1995
Abstract : Before beginning a widespread control program against Culex pipiens quinquefasciatus in Martinique, resistance to temephos, chlorpyrifos, and two organophosphorous insecticides, was investigated at seven breeding sites. At LC95, populations exhibited resistance ratios between 6.9 and 11.6 for temephos and between 6.4 and 51.4 for chlorpyrifos. Overproduced esterases A2-B2 and B1, known to be involved in organophosphorous-resistance, were present at all breeding sites; esterases A2-B2 frequency was > 50% at all sites but one; and esterase B1 frequency was < 7%. Experimental treatment of three breeding sites with temephos induced no significant increase in resistance, but our esterase studies indicated a significant increase in the frequencies of esterase B1 and of a new highly active esterase C2. These results indicate that a large-scale C. p. quinquefasciatus control program with organophosphorous insecticides will induce a rapid increase of these resistance genes throughout Martinique. However, this may not necessarily result in high levels of resistance, because, at present, the level of gene amplification of esterase B still appears to be low.
ESTHER : Yebakima_1995_J.Med.Entomol_32_77
PubMedSearch : Yebakima_1995_J.Med.Entomol_32_77
PubMedID: 7541837

Title : Resistance monitoring in Culex pipiens (Diptera: Culicidae) from central-eastern France - Rivet_1994_J.Med.Entomol_31_231
Author(s) : Rivet Y , Raymond M , Rioux JA , Delalbre A , Pasteur N
Ref : Journal of Medical Entomology , 31 :231 , 1994
Abstract : Insensitive acetylcholinesterase (AceR) and five over-produced esterases (A1, A2 and B2, and A4 and B4) involved in detoxification are responsible for resistance to organophosphorous insecticides (OPs) in Culex pipiens L. from the Rhne-Alpes region, where C. pipiens control is mainly accomplished with the OPs temephos and chlorpyrifos using 0.15 mg/liter doses. The strong linkage disequilibria observed between esterases A1 and Est-20(0.64), esterases A4 and B4, and esterases A2 and B2 indicate that these genes were introduced in the Rhne-Alpes region. AceR and esterase A1, which appeared in the south of France 3 yr before the start of mosquito control in Rhne-Alpes, had the highest frequencies. All resistant genotypes were shown to be killed by 0.15 mg/liter temephos in natural breeding sites, but not by 0.15 mg/liter chlorpyrifos. These results are discussed in relation with mosquito control strategies.
ESTHER : Rivet_1994_J.Med.Entomol_31_231
PubMedSearch : Rivet_1994_J.Med.Entomol_31_231
PubMedID: 7514668

Title : Insecticide susceptibility in mosquitoes (Diptera: Culicidae) from French Polynesia - Failloux_1994_J.Med.Entomol_31_639
Author(s) : Failloux AB , Ung A , Raymond M , Pasteur N
Ref : Journal of Medical Entomology , 31 :639 , 1994
Abstract : Susceptibility to six organophosphate (OP), two pyrethroid (PY), and one carbamate (C) insecticides was investigated in Culex pipiens quinquefasciatus Say, Aedes aegypti (L.), and Aedes polynesiensis Marks larvae from the island of Tahiti. Cx. p. quinquefasciatus and Ae. aegypti were compared with susceptible reference strains treated simultaneously. A low, but significant, resistance to bromophos (4.6x), chlorpyrifos (5.7x), fenthion (2.4x), fenitrothion (5.0x), temephos (4.3x) and permethrin (2.1x) was found in Cx. p. quinquefasciatus, and to malathion (1.5x), temephos (2.3x), permethrin (1.8x) and propoxur (1.7x) in Ae. aegypti. Cx. p. quinquefasciatus was shown to possess over-produced esterases A2 and B2, which are known to be involved in resistance to OPs in other countries. Ae. polynesiensis was less resistant than the Ae. aegypti reference strain to all insecticides except temephos (1.8x) and permethrin (6.7x). To determine whether Ae. polynesiensis had developed resistance to these insecticides in Tahiti, a geographical survey covering 12 islands of the Society, Tuamotu, Tubuai, Marquesas, and Gambier archipelagoes was undertaken with three insecticides (temephos, deltamethrin, and permethrin). Two- to threefold variations in LC50S were observed among collections. Results are discussed in relationship to the level of insecticide exposure on the different islands.
ESTHER : Failloux_1994_J.Med.Entomol_31_639
PubMedSearch : Failloux_1994_J.Med.Entomol_31_639
PubMedID: 7966164

Title : Action of Esterase B1 on Chlorpyrifos in Organophosphate-Resistant Culex Mosquitos - Cuany_1993_Pestic.Biochem.Physiol_45_1
Author(s) : Cuany A , Handani J , Berge J , Fournier D , Raymond M , Georghiou GP , Pasteur N
Ref : Pesticide Biochemistry and Physiology , 45 :1 , 1993
Abstract : Esterase B1 activity in Culex pipiens mosquitoes was strongly inhibited by oxidized organophosphates (OP), but not by nonoxidized forms or by carbamates. Inhibition by chlorpyrifos oxon and paraoxon remained total during the 2 hr following the removal of free insecticide molecules, indicating that hydrolysis by esterase B1 is either very slow or absent. This hypothesis was confirmed by comparing the fate of [14C]chlorpyrifos in larvae of strains TEM-R (with the over-produced esterase B1) and MSE (lacking an overproduced esterase). As expected, large quantities of chlorpyrifos oxon were observed in the two strains, but no other metabolite was found in TEM-R. It is concluded that esterase B1 confers resistance at least to diethyl OPs through sequestering rather than metabolism, as is also the case with the overproduced esterase E4 of Myzus persicae.
ESTHER : Cuany_1993_Pestic.Biochem.Physiol_45_1
PubMedSearch : Cuany_1993_Pestic.Biochem.Physiol_45_1
PubMedID:

Title : Mechanisms of insecticide resistance in field populations of Culex pipiens from Italy - Severini_1993_J.Am.Mosquito.Control.Assoc_9_164
Author(s) : Severini C , Romi R , Marinucci M , Raymond M
Ref : Journal of the American Mosquito Control Association , 9 :164 , 1993
Abstract : Results of a study on organophosphate (OP) resistance carried out on 4 Italian field populations of Culex pipiens are reported. The A1, A4-B4 and/or A5-B5 nonspecific esterases and insensitive acetylcholinesterase (AChE) were detected in our samples. A2-B2 esterases previously recorded in Italy were not observed. The A4-B4 and/or A5-B5 esterases were first found in Italy where they are at present widespread. Both nonspecific esterases and insensitive AChE are involved in OP resistance, although the high level of OP resistance observed in the Padova population could be correlated with both a high frequency of insensitive AChE and A5-B5 esterases.
ESTHER : Severini_1993_J.Am.Mosquito.Control.Assoc_9_164
PubMedSearch : Severini_1993_J.Am.Mosquito.Control.Assoc_9_164
PubMedID: 7688795

Title : Worldwide migration of amplified insecticide resistance genes in mosquitoes. - Raymond_1991_Nature_350_151
Author(s) : Raymond M , Callaghan A , Fort P , Pasteur N
Ref : Nature , 350 :151 , 1991
Abstract : In Culex pipiens, overproduction of nonspecific esterases is a common mechanism of resistance to organophosphate insecticides. The esterases are attributed to closely linked loci named A and B according to substrate preference, and overproduction of all esterases B is due to gene amplification. Distribution of electrophoretically distinct variants of overproduced esterases A and B is geographically restricted, with the exception of esterases A2 and B2, always found together throughout at least three continents. To determine whether this situation is due to migration or to a high mutation rate, esterase B structural genes and their flanking regions were compared by sequence and/or restriction fragment length polymorphism analysis. Whereas structural genes were similar, flanking regions of electrophoretically dissimilar esterases B varied considerably. In contrast, flanking sequences of esterases B2 from different geographical locations (Africa, Asia, North America) were identical. These results suggest that amplified esterase B2 genes originated from an initial event that has subsequently spread organophosphate insecticide resistance by migration.
ESTHER : Raymond_1991_Nature_350_151
PubMedSearch : Raymond_1991_Nature_350_151
PubMedID: 2005964

Title : Amplification of various esterase B's responsible for organophosphate resistance in Culex mosquitoes -
Author(s) : Raymond M , Beyssat-Arnaouty V , Sivasubramanian N , Mouches C , Georghiou GP , Pasteur N
Ref : Biochemical Genetics , 27 :417 , 1989
PubMedID: 2559713

Title : Identification of resistance mechanisms in Culex pipiens (Diptera: Culicidae) from southern France: insensitive acetylcholinesterase and detoxifying oxidases -
Author(s) : Raymond M , Fournier D , Bride JM , Cuany A , Berge JB , Magnin M , Pasteur N
Ref : J Econ Entomol , 79 :1452 , 1986
PubMedID: 3805481

Title : Amplification of an esterase gene is responsible for insecticide resistance in a California Culex mosquito - Mouches_1986_Science_233_778
Author(s) : Mouches C , Pasteur N , Berge JB , Hyrien O , Raymond M , de Saint Vincent BR , de Silvestri M , Georghiou GP
Ref : Science , 233 :778 , 1986
Abstract : An esterase gene from the mosquito Culex quinquefasciatus that is responsible for resistance to a variety of organophosphorus (OP) insecticides was cloned in lambda gt11 phage. This gene was used to investigate the genetic mechanism of the high production of the esterase B1 it encodes in OP-resistant Culex quinquefasciatus Say (Tem-R strain) from California. Adults of the Tem-R strain were found to possess at least 250 times more copies of the gene than adults of a susceptible strain (S-Lab). The finding that selection by pesticides may result in the amplification of genes encoding detoxifying enzymes in whole, normally developed, reproducing insects emphasizes the biological importance of this mechanism and opens new areas of investigation in pesticide resistance management.
ESTHER : Mouches_1986_Science_233_778
PubMedSearch : Mouches_1986_Science_233_778
PubMedID: 755546

Title : Single-mosquito test to determine genotypes with an acetylcholinesterase insensitive to inhibition to propoxur insecticide - Raymond_1985_J.Am.Mosquito.Control.Assoc_1_425
Author(s) : Raymond M , Fournier D , Berge JB , Cuany A , Bride JM , Pasteur N
Ref : Journal of the American Mosquito Control Association , 1 :425 , 1985
Abstract : A sensitive technique allowing to identify the three genotypes (AceSS, AceRR and AceRS) of the Ace gene existing in natural populations of Culex pipiens in southern France is described. The technique is based on the comparison of AChE (acetylcholinesterase) activity in 3 equal aliquots taken from the homogenate of a single mosquito (a) in absence of inhibitor (RA), (b) in presence of eserine that inhibits the AChE encoded by AceS and AceR alleles (RI) and (c) in presence of a concentration of propoxur inhibiting the AChE coded by the AceS allele but not by the AceR allele (RG). The mosquito tested is AceSS when RG = RI, AceRR when RG = RA and AceRS when RI less than RG less than RA.
ESTHER : Raymond_1985_J.Am.Mosquito.Control.Assoc_1_425
PubMedSearch : Raymond_1985_J.Am.Mosquito.Control.Assoc_1_425
PubMedID: 3880259