Genetic Basis for DDT resistance associated with Cyp6g1 in Drosophila simulans Open Access

Abstract

Insecticide resistance is an important example of anthropogenic driven evolution: With the wide spread use of insecticides we have experienced the rapid development of resistant phenotypes in many ins ect species. This is a recurrent reality encountered by many public health initiatives, including those undertaken to control malaria. Moving forward, a thorough understanding of the mechanisms of resistance will be essential to generating the next generation of insecticides. In effort to elucidate the molecular and evolutionary mechanisms behind insecticide resistance, researchers have turned to non-target species, such as Drosophila melanogaster, which have demonstrated significant field resistances to pesticides such as DDT. One classic example of such a mutation is the Accord transposon inserted in the 5' regulatory region of the DDT-resistance gene CYP6g1 of Drosophila melanogaster. This mutation is associated with constitutive Cyp6g1 over-expression and insecticide resistance. A similar mutation was found in Drosophila simulans, whereby a Doc transposable element inserted in the 5' regulatory region of Cyp6g1 also associated with increased Cyp6g1 expression and insecticide resistance. We have made several reporter constructs to identify the specific Doc gene sequences necessary for Cyp6g1 over-expression. Furthermore, to better understand the functional consequences of the D. simulans Cyp6g1 Doc insertion, we have characterized the tissue-specific expression pattern of CYP6g1 in Doc+ and Doc- strains. These findings may contribute to a larger understanding of the mechanism of resistance in insect species.

Table of Contents

Table of Contents

Introduction 1

Methods 7

Results 10

Discussion 13

Figures and Tables:

Figure 1:

Location of the Doc transposon insertion in DDT-resistant D. simulans 18

Figure 2:

Fractional Survival of adult Sim6(Doc+) and Sz3(Doc-) across DDT concentrations. 19

Figure 3:

Transcript length of Cyp6g1 in Sim6 (Doc+) and Sz3 (Doc-). 20

Figure 4:

Reporter constructs for characterization of Cyp6g1 expression. 21

Figure 5:

Tissue specific expression of reporter driven by 6g1promoter and Doc+6g1promoter in 3^rd instar larvae. 22

Figure 6:

Tissue specific expression of reporter driven by 6g1promoter and Doc+6g1promoter in adult transgenics. 23

Figure 7:

Tissue specific expression of Cyp6g1 in Sim6 (Doc+) and Sz3 (Doc-)

3^rd instar larvae. 24

Figure 8:

Tissue specific expression of Cyp6g1 in Sim6 (Doc+) and Sz3 (Doc-)

adults. 25

Figure 9:

Tissue specific expression of DocHsp70 in 3^rd instar larvae. 27

Figure 10:

Tissue specific expression driven by DocHsp70 in adults. 28

Table 1:

Relative quantification of tissue specific Cyp6g1 expression compared

to RP49 in Sim6 (Doc+) and Sz3 (Doc-). 26

References 29

About this Master's Thesis

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School	Rollins School of Public Health
Department	Environmental Health
Degree	MPH
Submission	Master's Thesis
Language	English
Research Field	Health Sciences, Public Health Biology, General
Keyword	DDT Malaria Insecticide resistance
Committee Chair / Thesis Advisor	Miller, Gary W, Emory University
Committee Members	Tolbert, Paige, Emory University Schlenke, Todd, Emory University
Partnering Agencies	Does not apply (no collaborating organization)

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