Effect of Nicotine on Spitz Gene Expression in Drosophila melanogaster

Abstract

In humans, nicotine is known to cause various diseases including Cancer, impaired fertilization, insulin resistance, and Metabolic Syndrome. Exposure to nicotine typically occurs via the inhalation of cigarette or cigar smoke (primary or secondary) and vaping. The Spitz gene in Drosophila melanogaster codes for a RAS signaling protein that is involved in a variety of differentiation processes, including ventralization of the embryo. Because RAS mutations are found in 33% of cancerous tumors, using nicotine, a carcinogen, was hypothesized to cause increased expression of Spitz. Also, because nicotine causes aggression in human males, we hypothesized that male flies would show aggressive behavior after nicotine exposure, manifesting in the form of headbutting and lunging at one another. To test these hypotheses, we exposed our Drosophila larvae cultures to a 2% nicotine solution that was mixed with their food. After one week of exposure, the control and experimental groups were analyzed using an aggression behavioral assay and Reverse Transcription quantitative Polymerase Chain Reaction (RT-qPCR) which was performed on the extracted fly RNA to determine the expression level of Spitz. Because our Drosophila larvae were exposed to nicotine early in development, we predicted there would be an over-expression of the Spitz gene in the experimental group.