Effects of Oxidative Stress in Intestines of Caenorhabditis elegans

Abstract

Stress is a major phenomenon present in lives of all organisms in the planet. Organisms respond differently to various kinds of stress. For example, some common types of stress experienced during a lifetime are salt, heat, or oxidative stress. This experiment attempts to discover the ubiquitin stress response in the intestines of Caenorhabditis elegans under oxidative stress. Caenorhabditis elegans are used to study stress because proteins that respond to stress such as ubiquitin are highly conserved. Ubiquitin in C. elegans and ubiquitin in humans differ only by one amino acid which makes them 98.68% genetically identical. Therefore, carefully studying the ubiquitin response in C. elegans gives us a good understanding of the way it works in humans as well. ERT 261 and ERT 264 (intestinal strains) one day adult Caenorhabditis elegans were treated with hydrogen peroxide for oxidative stress, sodium chloride for salt stress (positive control), and M9 buffer for an unstressed condition (negative control). Previously, Dr. Lynn Boyd’s lab has looked at salt stress in the intestine and both salt and oxidative stress in the gonads. In both the cases, nuclear spheres (referred to as foci) were observed, ubiquitin being a major component of it. Foci are the spherical regions enriched with ubiquitin observed with in the nuclei of cells under stress conditions. In this experiment, foci were observed in the intestinal tissue of C. elegans under oxidative stress. In addition to whether or not nuclear spheres formed in the intestine, this experiment used different concentrations of hydrogen peroxide to cause different levels of oxidative stress and thus a relationship between the level of oxidative stress and the percentage of nuclei with spheres observed was developed. At 5mM, 50% of the ERT iv 261 had nuclear spheres, while at 10mM and 15mM it was 44% and 58%. To take the experiment another step further, recovery period for up to 24 hours was allowed and the percentage of nuclei with foci were observed. A decrease by a 9% in M9, 25% in 500mM sodium chloride, 42% in 5mM, 36% in 10mM, and 42% in 15mM of hydrogen peroxide was observed after the 12 hours recovery period when compared to those after 1 hour of stressing. However, no spheres were observed after 24 hours due to intense auto fluorescence in the intestinal strain of Caenorhabditis elegans.