Examining the Effects of Glucose, Nicotine, and Ultraviolet Radiation on the RNAi Mechanism in Caenorhabditis Elegans

Overview

According to a 2012 National Institutes of Health report, 23.5 million Americans were reported to suffer from autoimmune diseases, conditions in which the body attacks itself. This category of diseases is still not fully understood, and they are thought to be highly complex, with both genetic and environmental factors contributing to susceptibility, onset, and development. Some hypotheses suggest that the epigenetic control of genes could influence the development of autoimmune diseases, creating a gene-environmental interaction that can cause disruptions in typical genetic expression. As autoimmune diseases become more prevalent and genetic therapies are developed to combat them, it is crucial to understand the effects that exposure to common environmental factors can have on the human genome. This study investigates the effects of three such factors – glucose, nicotine, and ultraviolet radiation – on the efficacy of the RNA interference (RNAi) gene silencing mechanism. It utilizes a modified Escherichia coli strain on two well-characterized and easily identifiable genes – bli-1 and dpy-11 – in the model organism Caenorhabditis elegans to quantify the effect of environmental factors on the efficacy of gene silencing. The successful introduction of the three variables tested into the nematodes’ environment was confirmed by a preliminary locomotion assay. The environmental factors were shown to have a significant effect on the organisms’ lateral tail movements and locomotion (ANOVA p<0.001), leading to a decrease in their overall movement and a decrease in taxis towards their food source, E. coli. Having confirmed that the changes in C. elegans behavior and appearance could be attributed to the three factors tested due to their successful introduction into the organism's’ environment, an RNAi assay was performed. The proportion of C. elegans simultaneously exposed to one of the three variables and the RNAi mechanism that displayed the phenotypes characteristic of the silenced genes (“blistered” cuticles for bli-1 silencing and the “dumpy” phenotype for dpy-11 silencing) was recorded and compared to the proportion of nematodes that displayed the same phenotypes in control RNAi groups. The resulting data were varied, but a Student’s t-test suggested that there was a significant difference in bli-1 gene silencing between the control and ultraviolet light-exposed group in the assay. The experimental data suggest that glucose, nicotine, and ultraviolet radiation can potentially affect gene transcription, as evidenced by noticeable differences in the outcomes between the control and experimental groups. The findings of this study merit a continuation of the investigation of the role of environmental factors in genetic expression and overall health as the human environment changes and genetic methods for disease control, prevention, and treatment continue to evolve.

Competition history

• AJAS 2018 Category not listed

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