Variation in Mitochondria-Derived Transcript Levels Associated With DDT Resistance in the91-RStrain ofDrosophila melanogaster(Diptera: Drosophilidae)

Abstract

The organochloride insecticide dichlorodiphenyltrichloroethane (DDT) and its metabolites can increase cellular levels of reactive oxygen species (ROS), cause mitochondrial dysfunction, and induce apoptosis. The highly DDT-resistant Drosophila melanogaster Meigen 1830 (Drosophila) strain, 91-R, and its susceptible control, 91-C, were used to investigate functional and structural changes among mitochondrial-derived pathways. Resequencing of mitochondrial genomes (mitogenomes) detected no structural differences between 91-R and 91-C, whereas RNA-seq suggested the differential expression of 221 mitochondrial-associated genes. Reverse transcriptase-quantitative PCR validation of 33 candidates confirmed that transcripts for six genes (Cyp12d1-p, Cyp12a4, cyt-c-d, COX5BL, COX7AL, CG17140) were significantly upregulated and two genes (Dif, Rel) were significantly downregulated in 91-R. Among the upregulated genes, four genes are duplicated within the reference genome (cyt-c-d, CG17140, COX5BL, and COX7AL). The predicted functions of the differentially expressed genes, or known functions of closely related genes, suggest that 91-R utilizes existing ROS regulation pathways of the mitochondria to combat increased ROS levels from exposure to DDT. This study represents, to our knowledge, the initial investigation of mitochondrial genome sequence variants and functional adaptations in responses to intense DDT selection and provides insights into potential adaptations of ROS management associated with DDT selection in Drosophila.

Reference-Guided De Novo Genome Assembly of the Flour Beetle Tribolium freemani

“…In addition to their most prevalent usage for molecular systematics at different taxonomic scales, mitochondrial genomes of some insects have been reported to be related to insecticide resistance. For example, changes in sequence and expression of some mitochondrial genes in the malaria vector Anopheles sinensis appeared to be associated with resistance to the pyrethroid insecticide [ 46 ], while changes in the expression level of mitochondrial-encoded genes in Drosophila melanogaster 91-R strain are linked to DDT resistance [ 47 ]. Differential expression of the genes related to mitochondrial functions was also found in the T. castaneum population resistant to phosphine, a fumigant used for stored products treatment to control pests [ 48 ].…”