Anopheles funestus is a major vector of malaria in the southern African region.
Insecticide resistance to pyrethroid and carbamate insecticides has been recorded in
populations of this species in South Africa and Mozambique. This study aimed to
determine the relationship between pyrethroid resistance and gene expression of two
closely related genes, CYP6P9 and CYP6P13, by age and sex in a resistant strain An.
funestus from southern Africa, FUMOZ-R. The insecticide susceptibility assays
showed that percentage survival in both FUMOZ-R sexes significantly decreased as
age increased. The mRNA expressions of CYP6P9 and CYP6P13 were higher in
FUMOZ-R relative to the insecticide susceptible strain (FANG). The expression of
permethrin resistance varies with age in An. funestus FUMOZ-R. The results indicate
that other genes may also be involved in insecticide resistance. In addition to this, the
expression profile of other metabolic genes involved in insecticide resistance was also
investigated. A microarray based approach was used to identify genes differentially
expressed in FUMOZ-R and FANG. As the full set of detoxification genes in An.
funestus are unknown, this study investigated the utility of the An. gambiae detox chip
to screen for differentially expressed detoxification genes in An. funestus. After
optimization of the hybridisation conditions, over 90% of the probes showed a
positive signal. Only three genes were significantly (P<0.001) differentially expressed
in the females, CYP6P9, COI and CYP6M7. The same genes were also significantly
differentially expressed in the adult males, together with an additional 21 transcripts.
The third part of this study investigated the gene expression in the first instar, fourth
instar and 3-day old adults in FUMOZ-R using the An. gambiae detox chip. The
variation in metabolic enzyme gene transcription at the different developmental stages in An. funestus are not known. The identification of differentially transcribed genes at
the different life stages provides some insight into the role and function of these
genes. A large number of cytochrome P450s (monooxygenases), esterases,
glutathione S-transferases (GSTs) and other additional genes were differentially
expressed in all life stages. This study provided vital information regarding genes
potentially involved in pyrethroid resistant and is the first to provide metabolic or
detoxifying transcription gene information in An. funestus.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:wits/oai:wiredspace.wits.ac.za:10539/10961 |
| Date | 11 January 2012 |
| Creators | Christian, Riann N |
| Source Sets | South African National ETD Portal |
| Language | English |
| Detected Language | English |
| Type | Thesis |
| Format | application/pdf, application/pdf |
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