Epsilon Archive for Student Projects

Abstract

Dictyostelium discoideum has long been used as a model organism to study many different biological processes. The amoeba is very similar to macrophages present in higher animals, for example humans. Furthermore, several genes in D. discoideum have shown to be homologous with human genes. Due to these facts, D. discoideum have also been used to study host-pathogen interactions with many different human pathogens. In this project, the aim was to survey the literature and find conditions where the pathogen Salmonella typhimurium can infect D. discoideum and further try to explain how this host-pathogen system can be used to study how non-coding RNAs can influence the infectious process.

S. typhimurium is a pathogen that is known to infect humans and other animals. When infection occurs it causes gastroenteritis that gives diarrhea and vomiting. The pathogen causes infection by entering host cells, such as macrophages or epithelial cell. Inside the host cells the pathogen can find ways to replicate and persist. ncRNAs are important molecules that regulate many different processes in the cell by either induce degradation of mRNA or inhibit translation. Two of the most important groups of ncRNAs are microRNAs and small interfering RNAs. These are the two groups that would be studied in order to try to elucidate their role and function during the infectious process.

How the project would be set up will be described in this literature project. The first thing that would be done is to try to find conditions were S. typhimurium can infect D. discoideum; to do this a microtitre plate assay would be used to try to find the right conditions. This allows screening of a large number of different conditions simultaneously. Total RNA would then be extracted from both non-infected and infected D. discoideum cells. Both small RNAs and mRNA would be analyzed using high throughput sequencing methods. The results would then be used to create mutants where the identified ncRNAs are knocked out or over–expressed in order to elucidate their function. ncRNA target genes would also be mutated, in order to understand their function. Which role ncRNAs have in S. typhimurium during the infectious process would also be analyzed. By studying these factors, the biology behind the infection of S. typhimurium could be identified.