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1.
Acetylcholinesterase from the heads of insecticide-resistant and -susceptible houseflies (Musca domestica L.) was studied in vitro. The enzymes could not be distinguished electrophoretically, and their behaviour on polyacrylamide-disc-gel electrophoresis was influenced by the presence of Triton X-100 in both the homogenate and the gels. In the absence of detergent, the acetylcholinesterase was heterogeneous, but behaved as a single enzyme when it was present. By analogy with studies of acetylcholinesterase from other sources, these observations were attributed to aggregation of the enzyme when not bound by membranes. The enzyme from resistant flies was more slowly inhibited than the susceptible enzyme, bimolecular rate constants (ki) differing by approx. 4-20-fold for a range of organophosphorus compounds. The kinetics of inhibition of acetylcholinesterase were consistent with the results of electrophoresis, i.e. they corresponded to those of a single enzyme in the presence of Triton X-100, but a mixture of enzymes in its absence. The susceptibility of the more sensitive components in these mixtures was determined.  相似文献   

2.

Background

Seasonal fluctuations in susceptibility to organophosphate insecticides were observed in the Katsunuma population of Drosophila melanogaster for two consecutive years; susceptibility to three organophosphates tended to increase in the fall. To examine the hypothesis that variation in fitness among resistant and susceptible genotypes could trigger the change of genetic constitution within the fall population, we investigated density-independent population projection trajectories starting from single adult females with characteristics of chromosome-substituted lines resistant and susceptible to the three organophosphates.

Results

Density-independent population projection trajectories, expressed as the ratios of the number of each chromosome-substituted line to that of line SSS, for which all chromosomes were derived from the susceptible line, showed significant declines in numbers with time for all the resistant chromosome-substituted lines.

Conclusion

The declining tendency in the density-independent population projection trajectories of the resistant chromosome-substituted lines could explain the simultaneous decline in the levels of resistance to the three organophosphates, observed in the Katsunuma population in the fall.  相似文献   

3.
To investigate the genetic basis of the seasonal fluctuations in resistance to three organophosphates, observed within a natural population of Drosophila melanogaster (Meigen), we compared the intrinsic rate of increase, generation time and net reproduction rate among chromosome substitution lines derived from a resistant and a susceptible line, obtained from this natural population. There was significant variation among substituted lines; lines possessing the third chromosome from the resistant line, which confers resistance to the three organophosphates, generally showed lower mean values of these fitness measures. Chromosomal analyses also indicated significant negative contributions of the third chromosome from the resistant line. However, significant positive contributions of the interactions among chromosomes from the resistant line to these fitness measures were also detected. We further conducted a local stability analysis, in which each chromosome-substituted line was assumed to be introduced at a low frequency into the initial susceptible population. It was demonstrated that the resistance factor(s) on the third chromosome tend to decrease in their frequency under both density-independent and juvenile density-regulated conditions. Based on these results, a possible explanation for the seasonal fluctuations in resistance to the three organophosphates observed in the natural population was proposed.  相似文献   

4.
5.
Median threshold responses of dieldrin-treated susceptible and resistant houseflies to sucrose solutions were compared to determine the exent of functional derangement produced by the toxicant in the central nervous system. ED50 values of sucrose were lowered below the level exhibited by untreated flies. The size of this effect depends on dose and length of exposure. The overall patterns of dieldrin-induced alterations in chemosensitivity were similar in the two strains except for the difference in the doses of the insecticide required to produce these changes. This difference in doses corresponded well with the difference in the susceptibility levels of the two strains to dieldrin. Sublethal/asymptomatic doses of the insecticide also produced increased sensitivity to sucrose in the resistant flies after 4–8 hours' exposure.
Résumé L'effet de la dieldrine sur le système nerveux central à été comparé chez des mouches sensibles et des mouches résistantes en déterminant leur sensibilité limite à des solutions de sucrose, au cours des différentes phases de l'intoxication et avec différentes doses. Il y a une apparente identité du syndrome de l'intoxication dans les deux lots de mouches, qui se manifeste par une augmentation de la sensibilité chimiotactile, la seule différence résidant dans la dose d'insecticide nécessaire pour produire ces changements. Il faut approximativement 5000 fois la dose de dieldrine causant le premier accroissement appréciable de sensibilité au sucrose chez les mouches sensibles, pour produire des effets comparables chez les mouches résistantes. On peut conclure que dans chacun des lots de mouches la résistance à la dieldrine peut s'exprimer d'après ses effets sur le comportement d'extension réflexe du proboscis en réponse à une solution de sucrose. Il y a corrélation entre le degré d'accroissement de la sensibilité chimiotactile et l'intensité de l'intoxication, que celle-ci soit produite par de fortes doses ou de plus longues expositions à de faibles doses. La sensibilité des mouches résistantes à une solution de sucrose est modifiée par des doses sublétales appliquées pendant un temps plus long, ce qui indique qu'un processus de restauration intervient.
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6.
The susceptibility of one susceptible and six resistant strains of houseflies to 13 organophosphorus compounds was measured with a contact method. Five of the strains had been selected, both in the field and in the laboratory, with diazinon, parathion or malathion. One strain had been strongly selected with -BHC. The susceptibility of the strains is shown in Fig. 1. The BHC selected strain had only a low level of resistance to organophosphates. Higher levels were present in all organophosphate selected strains, each of which exhibited its own characteristic resistance pattern. This indicates that a relatively large number of resistance mechanisms may be present.As resistance to the thiophosphates is of the same order of magnitude as that to their oxygen analogues, it follows that the resistance mechanism is not a slower conversion of the thiophosphates into the phosphates. Resistance to a number of dimethyl compounds is low, and little difference is present between the resistant strains. This resistance is probably brought about mainly by less specific factors. The genetical basis of the low aliesterase content of the phosphate resistant strains is discussed.
Zusammenfassung Die Empfindlichkeit eines normal-sensiblen und von sechs resistenten Stubenfliegen-Stämmen gegenüber 13 organischen Phosphorverbindungen wurde mit Hilfe einer Kontakt-Methode gemessen. Fünf dieser Stämme waren sowohl im Freiem wie auch im Labor, mit Diazinon, Parathion oder Malathion selektiert worden. Ein Stamm war stark mit -BHC selektiert worden. Die Empfindlichkeit der Stämme ist in Fig. 1 dargestellt. Der mit -BHC selektierte Stamm wies nur eine niedrige Resistenz gegenüber den organischen Phosphorverbindungen auf. Höhere Resistenz wurde in den mit organischen Phosphorverbindungen selektierten Stämmen gefunden; jeder dieser Stämmen zeigte eine eigene, charakteristische Form der Resistenz. Dies deutet darauf hin, daß eine relativ grössere Zahl von Resistenz-mechanismen vorhanden ist.Aus der Tatsache, daß Resistenz gegen die Thioverbindungen und ihre entsprechenden Sauerstoff-Analoge ungefähr gleich groß ist, wird geschlossen, daß eine langsamere Umwandlung in die Phosphate als Resistenz-mechanismus nicht in Betracht kommen kann.Die Resistenz gegenüber einigen Methyl-verbindungen ist gering, und in den einzelnen Stämmen nur wenig verschieden. Diese Resistenz wird wahrscheinlich durch weniger spezifisische Faktoren verursacht. Die genetische Grundlage des niedrigen Ali-esterasen-gehalts in den Phosphat-resistenten Stämmen wird diskutiert.
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7.
金莹  冯国蕾 《昆虫学报》2001,44(2):182-186
测定敏感、抗溴氰菊酯(Del-R)、抗氯菊酯(2Cl-R)的家蝇品系对有机磷杀虫剂敌敌畏、辛硫磷及马拉硫磷的LD50,α-乙酸萘酯(α-NA)酯酶动力学,酯酶的活性和酯酶的抑制作用。Del-R和2Cl-R的家蝇品系对三种有机磷杀虫剂的抗性倍数为0.966~7.190倍,均为低抗水平。三个家蝇品系的羧酸酯酶活性水平与抑制中浓度存在正相关性,说明羧酸酯酶在抗拟除虫菊酯家蝇对有机磷杀虫剂的抗性中起一定的作用。  相似文献   

8.
A S Perry 《Life sciences》1970,9(6):335-350
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9.
The response of a susceptible strain and the diazinon-selected strain of houseflies, the SKA, to 20 organophosphorus insecticides was measured by topical application and injection.The SKA strain was very resistant to diazinon, ethyl chlorthion, chlorthion and parathion, moderately resistant to five other insecticides and only slightly resistant to the remainder. It was more resistant to the diethoxy than dimethoxy compounds and was only very slightly resistant to malathion. The compounds, especially the phosphates, were more toxic when injected than when applied topically. Additions or substitutions in the phenyl ring of the parathion molecule resulted in compounds less toxic than parathion, particularly to susceptible flies.
Zusammenfassung Die Reaktion eines anfälligen und des auf Diazinonresistenz ausgelesenen Stammes SKA der Stubenfliege auf Organophosphor-Insektizide wurde nach topischer Applikation und Injektion gemessen.Der SKA-Stamm war sehr widerstandsfähig gegen Diazinon, Äthylchlorthion, Chlorthion und Parathion, mäßig resistent gegen fünf andere Insektizide und nur schwach resistent gegen die übrigen. Er war gegen die Diäthoxy-Verbindungen widerstandsfähiger als gegen Dimethoxy-Verbindungen und gegen Malathion nur sehr schwach resistent. Die Verbindungen, insbesondere die Phosphate, wirkten injiziert giftiger als bei äußerer Applikation. Additionen und Substitutionen im Phenyl-Ring des Parathion-Moloküls ergaben Verbindungen, die besonders gegen anfällige Fliegen weniger toxisch wirken.
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10.
Cholinesterase activity of orgnophosphorus-susceptible and resistant cattle ticks (Boophilus microplus) has been determined, and found to be much lower in the resistant strain. Experiments on inhibition of tick cholinesterases by organophosphates indicated that the resistant strain possessed at least one cholinesterase which reacted more slowly with organophosphates than did the cholinesterase of the susceptible strain. The greatest difference of reaction rate occurred with compounds which give the largest factors of resistance under bio-assay conditions. The organophosphate resistant cholinesterase was also less rapidly inhibited by carbamates. A strain of the blue tick (B. decoloratus), which is resistant to arsenic and chlorinated hydrocarbon insecticides, had normal levels of cholinesterase activity, and this enzyme was fully susceptible to organophosphate inhibition.
Zusammenfassung Die Cholinesterase-Aktivität bei organophosphat-empfindlichen und-resistenten Viehzecken (Boophilus microplus) wurde bestimmt und im resistenten Stamm viel niedriger befunden. Versuche über die Hemmbarkeit der Zecken-Cholinesterasen durch Organophosphate wiesen darauf hin, daß der resistente Stamm mindestens eine Cholinesterase hat, die langsamer mit Organophosphaten reagiert als die des empfindlichen Stammes. Der größte Unterschied in den Reaktionsgeschwindigkeiten fand sich bei denjenigen Verbindungen, welche under den Bedingungen des biologischen Testes den größten Resistenzfaktor aufwiesen. Die organophosphatresistente Cholinesterase wurde auch durch Karbamate langsamer gehemmt. Ein Stamm der blauen Zecke (Boophilus decoloratus), der gegen Arsen sowie chlorierte Kohlenwasserstoffe resistent ist, zeigte normale Stufen von Cholinesterase-Aktivität; und dieses Enzym war voll empfindlich gegenüber Organophosphat-Hemmung.
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11.
12.
The metabolic fate of malathion in susceptible and organophosphate resistant strains of houseflies was studied by means of radioisotope-techniques, in vivo and in vitro. The main interstrain difference was the superior ability of the two malathion resistant strains to degrade malathion to its monocarboxylic acid derivative. Attempts were made to characterize the carboxyesterases responsible for this difference with respect to heat stability, pH dependency and organophosphate inhibition, and to estimate their importance in causing resistance by means of cross-resistance and synergism experiments. The relation to, and possible identity of the carboxyesterases with, the malaoxon degrading enzymes previously found in the malathion resistant strains is discussed.
Zusammenfassung Der Malathionmetabolismus wurde mit Hilfe der Radioisotopentechnik in normal empfindlichen und organophosphatresistenten Stubenfliegenstämmen in vivo und in vitro untersucht Die beiden malathionresistenten Stämme konnten Malathion besser in seinen Monocarboxylsäure-Abkömmling abbauen. Es wurde versucht, die hierfür verantwortliche Carboxyesterase hinsichtlich ihrer Hitzestabilität, pH-Abhängigkeit und Hemmbarkeit durch Organophosphate zu charakterisieren und ihre Bedeutung in der Resistenzbildung durch Kreuzungsresistenz- und Synergismusversuche zu bestimmen. Die Beziehung der besonders in den malathionresistenten Stämmen gefundenen malaoxonabbauenden Enzyme zu den Carboxyesterasen und ihre mögliche Identität mit denselben wird diskutiert.
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13.
Apple grain aphid, Rhopalosiphum padi (Linnaeus), is an important wheat pest. In China, it has been reported that R. padi has developed high resistance to carbamate and organophosphate insecticides. Previous work cloned from this aphid 2 different genes encoding acetylcholinesterase (AChE), which is the target enzyme for carbamate and organophosphate insecticides, and its insensitive alteration has been proven to be an important mechanism for insecticide resistance in other insects. In this study, both resistant and susceptible strains of R, padi were developed, and their AChEs were compared to determine whether resistance resulted from this mechanism and whether these 2 genes both play a role in resistance. Bioassays showed that the resistant strain used was highly or moderately resistant to pirimicarb, omethoate, and monocrotophos (resistance ratio, 263.8, 53.8, and 17.5, respectively), and showed little resistance to deltamethrin or thiodicarb (resistance ratio, 5.2 and 3.4, respectively). Correspondingly, biochemistry analysis found that AChE from resistant aphids was very insensitive to the first 3 insecticides (I50 increased 43.0-, 15.2-, and 8.8-fold, respectively), but not to thiodicarb (I50 increased 1.1-fold). Enzyme kinetics tests showed that resistant and susceptible strains had different AChEs. Sequence analysis of the 2 AChE genes cloned from resistant and susceptible aphids revealed that 2 mutations in Ace2 and 1 in Ace1 were consistently associated with resistance. Mutation F368(290)L in Ace2 localized at the same position as a previously proven resistance mutation site in other insects. The other 2 mutations, S329(228)P in Ace1 and V435(356)A in Ace2, were also found to affect the enzyme structure. These findings indicate that resistance in this aphid is mainly the result of insensistive AChE alteration, that the 3 mutations found might contribute to resistance, and that the AChEs encoded by both genes could serve as targets of insecticides.  相似文献   

14.
Serine esterases react with [3H]diisopropylphosphofluoridate ([3H]DFP) to produce radioactive adducts that can be resolved by denaturing slab gel electrophoresis. To identify an esterase or its catalytic subunit, a potential substrate was included in the reaction mixture with the expectation that it would suppress the enzyme's reaction with [3H]DFP. The nature of the enzyme could be inferred from the character of the substrates that suppress labeling. The validity of this analytical method was tested with two serine proteases, trypsin and alpha-chymotrypsin, and two serine esterases, acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE), and several of their natural or model substrates or inhibitors. Application of the method to complex biological systems was tested with chicken embryo brain microsomes. Trypsin labeling with [3H]DFP was suppressed by alpha-N-benzoyl-l-arginine ethyl ester (BAEE) and poly-l-lysine but not by benzoyl-l-tyrosine ethyl ester (BTEE). [3H]DFP labeling of chymotrypsin was suppressed by both BAEE and BTEE. Labeling of AChE and BuChE was suppressed by their natural and some related substrates and inhibitors. [3H]DFP reacted with brain microsomes to produce nine distinct radioactive bands. When the relevant substrates and inhibitors of AChE were included in the reaction mixtures, labeling of only the 95-kDa band was suppressed, implicating it as AChE. Labeling of the 85- and 79-kDa bands was inhibited by butyrylcholine, suggesting that these proteins have BuChE activity.  相似文献   

15.
Insecticide resistance in the codling moth, Cydia pomonella, partly results from increased metabolic detoxification. The aim of this study was to follow the age variations in larval susceptibility to deltamethrin and teflubenzuron in one susceptible (S) strain, and two resistant (Rv and Rt) ones selected for resistance to deltamethrin and diflubenzuron, respectively. The age variation of the activities of cytochrome P450-dependent monooxygenase (MFO), glutathione S-transferases (GST), and esterases in S and both resistant strains were simultaneously investigated. The highest levels of insecticide resistance were recorded in late instars in both resistant strains, although Rv neonates exhibited enhanced resistance to deltamethrin. The involvement of an additional deltamethrin-specific mechanism of resistance, which could be mainly expressed in early instars, was supported by previous demonstration of a kdr point mutation in the Rv strain. The cross-resistance between deltamethrin and teflubenzuron indicated the involvement of non-specific metabolic pathways in resistance to teflubenzuron, rather than target site modification. A positive correlation between enhanced GST activities and deltamethrin resistance suggested that this mechanism might take place into the adaptive response of C. pomonella to pyrethroids treatments. Enhanced MFO activity was recorded in each instar of the two resistant strains compared to the susceptible one. But these activities were not correlated to the responses to deltamethrin nor to teflubenzuron. In the light of these findings, studying age-dependence of responses to selection is central to the implementation of monitoring tests of resistances, especially if the target instars are difficult to collect in the field.  相似文献   

16.
17.
The paper reviews and reconsiders the experimental work on esterases in the housefly performed in the Laboratory for Research on Insecticides in Wageningen (formerly in Utrecht). It is attempted to integrate the different aspects of former studies, adding new data where necessary and possible. Two subjects that are intimately connected with esterases are briefly discussed, viz. the mode of action of organophosphorus insecticides and the mechanism of resistance to these compounds. A discussion on the possible functions of the esterases studied concludes the paper.
Zusammenfassung Die Arbeit gibt eine Übersicht über die experimentellen Untersuchungen an Esterasen der Stubenfliege, die im Laboratorium für Insektizid-Forschung durchgeführt wurden. Es wurde versucht, die verschiedenen Aspekte früherer Arbeiten zu integrieren; nötigenfalls sind neue Daten beigefügt. Zwei Probleme, die sehr eng mit der Aktivität von Esterasen verknüpft sind, nämlich der Wirkungsmechanismus der Phosphorsäureester und die Resistenz gegen diese Substanzen werden ebenfalls besprochen. Eine Betrachtung über die Funktion der Esterasen beschließt die Arbeit.


The material presented here was presented originally at the Symposium on the Function of Esterases in Animals, University of Recife, Recife, Pernambuco, Brazil, September 8–12. 1963.

Deceased on October 3, 1964.  相似文献   

18.
19.
ABSTRACT: BACKGROUND: Grapevine downy mildew, caused by Plasmopara viticola, is a very serious disease affectingmainly Vitis vinifera cultivated varieties around the world. Breeding for resistance throughthe crossing with less susceptible species is one of the possible means to reduce the diseaseincidence and the application of fungicides. The hybrid Bianca and some of its siblings areconsidered very promising but their resistance level can vary depending on the pathogenstrain. Moreover, virulent strains characterized by high fitness can represent a potential threatto the hybrid cultivation. RESULTS: The host response and the pathogen virulence were quantitatively assessed by artificiallyinoculating cv Chardonnay, cv Bianca and their siblings with P. viticola isolates derived fromsingle germinating oospores collected in various Italian viticultural areas. The hostphenotypes were classified as susceptible, intermediate and resistant, according to the AreaUnder the Disease Progress Curve caused by the inoculated strain. Host responses in cvBianca and its siblings significantly varied depending on the P. viticola isolates, which in turndiffered in their virulence levels. The fitness of the most virulent strain did not significantlyvary on the different hybrids including Bianca in comparison with the susceptible cvChardonnay, suggesting that no costs are associated with virulence. Among the individualfitness components, only sporangia production was significantly reduced in cv Bianca and insome hybrids. Comparative histological analysis revealed differences between susceptibleand resistant plants in the pathogen diffusion and cytology from 48 h after inoculation onwards. Defence mechanisms included callose depositions in the infected stomata, increasein peroxidase activity, synthesis of phenolic compounds and flavonoids and the necrosis ofstomata and cells immediately surrounding the point of invasion and determined alterations inthe size of the infected areas and in the number of sporangia differentiated. CONCLUSIONS: Some hybrids were able to maintain an intermediate-resistant behaviour even wheninoculated with the most virulent strain. Such hybrids should be considered for further fieldtrials.  相似文献   

20.
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