Establishing Drosophila melanogaster as a model for developmental neurotoxicity assessment of air pollutants using diesel exhaust - PROJECT SUMMARY
Air pollution is an emerging environmental risk factor for neurodevelopmental disorders (NDDs). Air pollution
consists of a complex mix of gases, hydrocarbons, metals, and particulate matter, the specific make-up of which
varies according to the source of the pollution. Further, different air pollution components have variable
neurotoxicity profiles and could have additive or synergistic impacts on the developing brain. Given the
increasing prevalence of NDDs, there is urgent need for in vivo models that enable rapid risk assessment of
different air pollution types to determine their impact on neurodevelopment. Additionally, NDDs often have
complex etiologies involving both environmental and genetic risk factors, making it critical to evaluate different
air pollutants in the context of genetic susceptibilities. We aim to establish the fruit fly, Drosophila melanogaster,
as a model for neurotoxicity profiling of air pollution because of its established utility in inhalation toxicity studies,
genetic tractability, conservation of human NDD risk genes, and suite of low-cost rapid behavioral paradigms for
experimental endpoints. To establish our model, we will use one specific source of air pollution: diesel exhaust
(DE). Laboratory and epidemiological studies of DE have demonstrated its ability to impair neurodevelopment in
organisms ranging from insects to humans. Thus, using DE to establish our model will allow us to determine
effective exposure parameters to elicit phenotypic responses and delineate associated metabolite markers of
neurotoxicity in the fly. In Aim I, we will vary the developmental stage (embryonic and larval) and DE dose (25,
100, 300, and 900 µg/m3) administered to wild-type Drosophila using a DE generator and inhalation chamber.
We will assess the response to both whole DE (particulate- and gas-phase) and filtered DE (gas-phase only) by
measuring: (1) two neurodevelopmentally programmed behaviors: adult courtship behavior and larval locomotor
activity, and (2) primarily endogenous chemical metabolites in larvae and adults from each exposure condition.
We expect to develop an effective DE exposure protocol, determine the impacts of DE on two innate Drosophila
behaviors, measure metabolites associated with neurotoxicity, and parse the differential impact of filtered and
unfiltered DE. In Aim II, we will use the exposure parameters established in Aim I to examine gene-environment
impacts of DE in a Drosophila model of fragile X syndrome (FXS), which have null mutations in fragile X mental
retardation 1 (dfmr1). Dfmr1 is the ortholog of human FMR1, which causes FXS and is the most common
monogenic cause of autism spectrum disorder. We will expose FXS flies to two doses of filtered and unfiltered
DE and compare the impact to control strains. Because FXS flies have significant defects in courtship, locomotor,
and grooming activity, we will examine all three innate behaviors as endpoints. We will again perform metabolic
profiling of larvae and adults from each exposure condition. This research will contribute to our understanding of
DE as an NDD risk factor and establish Drosophila as a model for rapid neurotoxicity testing of different air
pollution types, including assessment of gene-environment interactions relevant to NDDs.
