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Co-up-regulation of three P450 genes in response to permethrin exposure in permethrin resistant house flies, Musca domestica.

Zhu F, Li T, Zhang L, Liu N - BMC Physiol. (2008)

Bottom Line: Comparison of the deduced protein sequences of these three P450s from resistant ALHF and susceptible aabys and CS house flies revealed identical protein sequences.Genetic linkage analysis located CYP4D4v2 and CYP6A38 on autosome 5, corresponding to the linkage of P450-mediated resistance in ALHF, whereas CYP4G2 was located on autosome 3, where the major insecticide resistance factor(s) for ALHF had been mapped but no P450 genes reported prior to this study.Our study provides the first direct evidence that multiple P450 genes are co-up-regulated in permethrin resistant house flies through the induction mechanism, which increases overall expression levels of P450 genes in resistant house flies.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Entomology and Plant Pathology, Auburn University, Auburn, AL 36849, USA. fangzhudy@uky.edu

ABSTRACT

Background: Insects may use various biochemical pathways to enable them to tolerate the lethal action of insecticides. For example, increased cytochrome P450 detoxification is known to play an important role in many insect species. Both constitutively increased expression (overexpression) and induction of P450s are thought to be responsible for increased levels of detoxification of insecticides. However, unlike constitutively overexpressed P450 genes, whose expression association with insecticide resistance has been extensively studied, the induction of P450s is less well characterized in insecticide resistance. The current study focuses on the characterization of individual P450 genes that are induced in response to permethrin treatment in permethrin resistant house flies.

Results: The expression of 3 P450 genes, CYP4D4v2, CYP4G2, and CYP6A38, was co-up-regulated by permethrin treatment in permethrin resistant ALHF house flies in a time and dose-dependent manner. Comparison of the deduced protein sequences of these three P450s from resistant ALHF and susceptible aabys and CS house flies revealed identical protein sequences. Genetic linkage analysis located CYP4D4v2 and CYP6A38 on autosome 5, corresponding to the linkage of P450-mediated resistance in ALHF, whereas CYP4G2 was located on autosome 3, where the major insecticide resistance factor(s) for ALHF had been mapped but no P450 genes reported prior to this study.

Conclusion: Our study provides the first direct evidence that multiple P450 genes are co-up-regulated in permethrin resistant house flies through the induction mechanism, which increases overall expression levels of P450 genes in resistant house flies. Taken together with the significant induction of CYP4D4v2, CYP4G2, and CYP6A38 expression by permethrin only in permethrin resistant house flies and the correlation of the linkage of the genes with resistance and/or P450-mediated resistance in resistant ALHF house flies, this study sheds new light on the functional importance of P450 genes in response to insecticide treatment, detoxification of insecticides, the adaptation of insects to their environment, and the evolution of insecticide resistance.

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Time and dose-dependent induction of the expression of three genes was analyzed by qRT-PCR as described in the materials and methods. A. The duration of the gene expression following permethrin treatment at the dose of LD50 (10 μg/fly). B. The expression of the genes 24 h after permethrin treatment with a dose range of LD10 (5 μg/fly), LD50 (10 μg/fly), and LD90 (20 μg/fly). The relative level of gene expression shown in Y axis is the ratio of the gene expression in each treatment in comparison with that in acetone treated flies. The results are shown as the mean ± S.E.
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Figure 5: Time and dose-dependent induction of the expression of three genes was analyzed by qRT-PCR as described in the materials and methods. A. The duration of the gene expression following permethrin treatment at the dose of LD50 (10 μg/fly). B. The expression of the genes 24 h after permethrin treatment with a dose range of LD10 (5 μg/fly), LD50 (10 μg/fly), and LD90 (20 μg/fly). The relative level of gene expression shown in Y axis is the ratio of the gene expression in each treatment in comparison with that in acetone treated flies. The results are shown as the mean ± S.E.

Mentions: Based on this pilot experiment, we focused our study on CYP4D4v2, CYP4G2, and CYP6A38 in order to further characterize their overexpression in response to permethrin challenge in resistant and susceptible house flies using the quantitative real-time PCR (qRT-PCR) method, as described below under Materials and Methods. To minimize the possibility that these P450 genes have nothing to do with resistance but arose solely because of a strain-strain difference, the study used ALHF and two susceptible house fly strains, CS and aabys. To examine the effect of permethrin on induction of the three target P450s, we measured the expression of the genes in house flies challenged with permethrin at a corresponding dose range (LD10, LD50, and LD90) for various durations. Although no induction was detected in either the susceptible CS flies of the aabys for the dose range and time intervals tested (data not shown), our results showed that permethrin induced all three P450 genes in ALHF with varying levels in a time (24 h)- and dose (LD50 -10 μg/fly)-dependent manner (Fig. 5). Based on these data, a dose of 10 μg/fly and a time interval of 24 h were chosen for the further induction studies.


Co-up-regulation of three P450 genes in response to permethrin exposure in permethrin resistant house flies, Musca domestica.

Zhu F, Li T, Zhang L, Liu N - BMC Physiol. (2008)

Time and dose-dependent induction of the expression of three genes was analyzed by qRT-PCR as described in the materials and methods. A. The duration of the gene expression following permethrin treatment at the dose of LD50 (10 μg/fly). B. The expression of the genes 24 h after permethrin treatment with a dose range of LD10 (5 μg/fly), LD50 (10 μg/fly), and LD90 (20 μg/fly). The relative level of gene expression shown in Y axis is the ratio of the gene expression in each treatment in comparison with that in acetone treated flies. The results are shown as the mean ± S.E.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2567968&req=5

Figure 5: Time and dose-dependent induction of the expression of three genes was analyzed by qRT-PCR as described in the materials and methods. A. The duration of the gene expression following permethrin treatment at the dose of LD50 (10 μg/fly). B. The expression of the genes 24 h after permethrin treatment with a dose range of LD10 (5 μg/fly), LD50 (10 μg/fly), and LD90 (20 μg/fly). The relative level of gene expression shown in Y axis is the ratio of the gene expression in each treatment in comparison with that in acetone treated flies. The results are shown as the mean ± S.E.
Mentions: Based on this pilot experiment, we focused our study on CYP4D4v2, CYP4G2, and CYP6A38 in order to further characterize their overexpression in response to permethrin challenge in resistant and susceptible house flies using the quantitative real-time PCR (qRT-PCR) method, as described below under Materials and Methods. To minimize the possibility that these P450 genes have nothing to do with resistance but arose solely because of a strain-strain difference, the study used ALHF and two susceptible house fly strains, CS and aabys. To examine the effect of permethrin on induction of the three target P450s, we measured the expression of the genes in house flies challenged with permethrin at a corresponding dose range (LD10, LD50, and LD90) for various durations. Although no induction was detected in either the susceptible CS flies of the aabys for the dose range and time intervals tested (data not shown), our results showed that permethrin induced all three P450 genes in ALHF with varying levels in a time (24 h)- and dose (LD50 -10 μg/fly)-dependent manner (Fig. 5). Based on these data, a dose of 10 μg/fly and a time interval of 24 h were chosen for the further induction studies.

Bottom Line: Comparison of the deduced protein sequences of these three P450s from resistant ALHF and susceptible aabys and CS house flies revealed identical protein sequences.Genetic linkage analysis located CYP4D4v2 and CYP6A38 on autosome 5, corresponding to the linkage of P450-mediated resistance in ALHF, whereas CYP4G2 was located on autosome 3, where the major insecticide resistance factor(s) for ALHF had been mapped but no P450 genes reported prior to this study.Our study provides the first direct evidence that multiple P450 genes are co-up-regulated in permethrin resistant house flies through the induction mechanism, which increases overall expression levels of P450 genes in resistant house flies.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Entomology and Plant Pathology, Auburn University, Auburn, AL 36849, USA. fangzhudy@uky.edu

ABSTRACT

Background: Insects may use various biochemical pathways to enable them to tolerate the lethal action of insecticides. For example, increased cytochrome P450 detoxification is known to play an important role in many insect species. Both constitutively increased expression (overexpression) and induction of P450s are thought to be responsible for increased levels of detoxification of insecticides. However, unlike constitutively overexpressed P450 genes, whose expression association with insecticide resistance has been extensively studied, the induction of P450s is less well characterized in insecticide resistance. The current study focuses on the characterization of individual P450 genes that are induced in response to permethrin treatment in permethrin resistant house flies.

Results: The expression of 3 P450 genes, CYP4D4v2, CYP4G2, and CYP6A38, was co-up-regulated by permethrin treatment in permethrin resistant ALHF house flies in a time and dose-dependent manner. Comparison of the deduced protein sequences of these three P450s from resistant ALHF and susceptible aabys and CS house flies revealed identical protein sequences. Genetic linkage analysis located CYP4D4v2 and CYP6A38 on autosome 5, corresponding to the linkage of P450-mediated resistance in ALHF, whereas CYP4G2 was located on autosome 3, where the major insecticide resistance factor(s) for ALHF had been mapped but no P450 genes reported prior to this study.

Conclusion: Our study provides the first direct evidence that multiple P450 genes are co-up-regulated in permethrin resistant house flies through the induction mechanism, which increases overall expression levels of P450 genes in resistant house flies. Taken together with the significant induction of CYP4D4v2, CYP4G2, and CYP6A38 expression by permethrin only in permethrin resistant house flies and the correlation of the linkage of the genes with resistance and/or P450-mediated resistance in resistant ALHF house flies, this study sheds new light on the functional importance of P450 genes in response to insecticide treatment, detoxification of insecticides, the adaptation of insects to their environment, and the evolution of insecticide resistance.

Show MeSH