A NOVEL ROLE FOR CYTOCHROME P450 G 35 (CYP4G35) IN ODOR PROCESSING IN AEDES AEGYPTI MOSQUITOES
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Authors
Garcia Cruz, Omar
Issue Date
2023
Type
Thesis
Language
Keywords
Aedes aegypti , CYP4G35 , Odor degradation , Odor degrading enzyme , Olfaction
Alternative Title
Abstract
Mosquitoes are vectors of various pathogens important to human health. The emergence of insecticide resistance has put pressure on identifying new avenues for mosquito control. These genetics tools require novel targets, which only come with a better understanding of mosquito biology. Chemo sensation is essential for insects to interpret their environments. Three primary appendages mediate chemoreception, esp. olfaction in mosquitoes: antennae, maxillary palps, and proboscis. These appendages have sensilla hairs covering their exterior structure. The sensilla hair houses many chemoreceptors, including odorant, ionotropic, and gustatory receptors. The volatile odorants enter the sensilla lymph through pores to bind to the receptors. Maintaining odor receptor sensitivity through degrading these odorants is essential for odor perception. Many enzymes, such as esterases and cytochrome P450s (CYPs), have been hypothesized to function as odor-degrading enzymes; however, none is yet functionally characterized. Most insects have 1 or 2 CYP4G genes, an insect-specific class of CYPs. The Dipteran insect genomes have two genes. Similar to other dipterans, the Ae. aegypti genome expresses two CYP4G genes: CYP4G36 (CYP4G1) and CYP4G35 (CYP4G15). Previous work in the Gulia-Nuss and Blomquist labs showed that Ae. aegypti CYP4G36 is an oxidative decarbonylase that catalyzes the last two steps in cuticular hydrocarbon synthesis, a function consistent with the findings in other insects (unpublished data). From the preliminary data in the Gulia-Nuss lab, we hypothesized that CYP4G35 is an odor-degrading enzyme (ODE). An important consideration for an ODEs is its localization. If CYP4G35 were to have an olfactory function, it would need to localize in the sensilla (Chapter 2). To understand the potential pathways in which CYP4G35 might be involved, we knockout CYP4G35 in mosquitoes. We separated both mutant and wild-type samples' head and carcass/body tissue to identify head-specific differences in protein expression in CYP4G35 mutant mosquitoes (Chapter 3). To identify the direct target (substrate) for the CYP4G35 enzyme, we expressed CYP4G35 and used these microsomes with different chained-length alcohol and aldehyde substrates (Chapter 4). GC-MS was used to analyze the breakdown product of a particular substrate. Our data support our hypothesis that CYP4G35 has a function in odor perception. However, it is unclear whether it directly breaks down odor molecules or is a general detoxification enzyme that helps clear the lymph to avoid odor molecule buildup.