Dysfunction of the Fragile X mental retardation (FMR1) gene results in the genetic disorder Fragile X syndrome (FXS), a primary cause of Autism Spectrum Disorder (ASD). FXS patients exhibit developmental delays and learning disabilities. Although researchers have also reported immune dysregulation in FXS patients, and the fruit fly Drosophila, the role FMR1 plays in immune function is not well understood. To help fill this knowledge gap, we use RNA-interference (RNAi) to inhibit fmr1 gene function in the cricket Acheta domesticus, and then examine the impact of this gene knock-down on the immune response. In a previous study, we knocked-down fmr1 expression in male and female crickets and then exposed the crickets to a bacterial challenge. Interestingly, 80% of males died from this infection, while only 15% of females died. To study this sexually dimorphic immune response following fmr1 RNAi, we first asked if basal fmr1 expression differs between males and females. To answer this, we removed the fat body (FB), an important immune tissue, from adult crickets and used quantitative real-time PCR (qPCR) to quantify fmr1 expression. We found that females have 47% greater fmr1 expression in the thoracic FB and 40% greater fmr1 expression in the brain FB relative to males. Our plan is to also compare fmr1 expression in male and female FB during infection, and to use Western blotting to quantify the levels of Fragile X Mental Retardation Protein (FMRP), the protein product of the fmr1 gene, in males and females following RNAi and during infection. While we are still collecting data, we believe this study will provide important insight into the role of fmr1 in immunity. As an aspiring physician, this DUOS project has allowed me direct insight into a disorder that I may encounter in the future and has enriched my critical thinking skills, which I will carry into my future career.
Author: Alexander Szymczak, Biochemistry and Economics Major
Advisor: Kathleen Killian, Ph.D. Department of Biology
Graduate Advisor: Mackenzie Farleigh, Biology
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