Diet and Obesity: An Experimental Study of the Contribution of Antibiotics & High Sugar Diet to Triglyceride Accumulation in Drosophila melanogaster

Abstract

The cost of obesity is increasing dramatically reaching almost $2 trillion per year, making understanding obesity pathology imperative. While both environmental and genetic factors are shown to contribute to fatty acid accumulation and obesity development, the relative contribution of each is poorly understood. Genetic explanations of obesity alone are inadequate, as SNPs alone do not fully explain obesity heritability, and thus environmental factors are of interest. Of particular interest are the effects of high sugar and antibiotic on consumption. Antibiotic consumption is shown to increase weight in many animals, but no studies have determined the mechanism behind weight increase or tested this phenomenon in Drosophila. As a preliminary study I quantify Drosophila Canton-S feeding behavior using the CAFE assay. I then use LC-MS to quantify the extent to which fatty acid synthesis and overall fatty acid abundance differs between high sugar and control diet Drosophila. By feeding C13 labeled fructose and performing isotope abundance correction, I observe higher fatty acid abundance levels and greater fatty acid synthesis in high sugar fed flies than control. I then seek to understand the influence of high sugar and antibiotics on triglyceride levels using a colorimetric assay. I first determine that acute capillary feeding significantly increases triglyceride abundance. I then find long term antibiotic (Tetracycline and Ampicillin) and high sugar treatments significantly enrich triglyceride levels as well. All treatments are compared to control fed flies and significance tested using Mann Whitney U statistical test. Since antibiotic induced fat increase has been previously observed in vertebrates, I seek to validate Drosophila melanogaster as a model organism for further studies of the effect of antibiotic consumption on fatty acid accumulation. I find that environmental components including antibiotic and high sugar diets do significantly influence triglyceride synthesis and triglyceride amount, however, further study of Drosophila as a model system are needed to understand the underlying biochemical mechanisms responsible.