Student Research

Oxidative stress response in the seaside sparrow (Ammospiza maritima) following the Deepwater Horizon oil spill

The Deepwater Horizon (DWH) oil spill introduced massive amounts of oil into Louisiana saltmarsh ecosystems. The main toxic component of DWH oil are polycyclic aromatic hydrocarbons (PAHs). PAH metabolites react with molecular oxygen to create reactive oxygen species (ROS) via a redox cycling reaction. The relatively unstable ROS can then cause oxidative damage to organic molecules, inducing oxidative stress when they overcome antioxidant defenses in the organism. Our goal is to quantify the oxidative stress response of seaside sparrows (Ammospiza maritima) exposed to DWH oil. We will be measuring plasma and tissue levels of reactive oxygen metabolites (ROMs) and antioxidant barrier strength using commercial kits. We will also be measuring cardiac tissue levels of glutathione (GSH), an endogenous antioxidant that aids in combatting pro-oxidants, mitigating oxidative stress. Finally, we will measure protein carbonyl content, a measure of oxidative damage to proteins, using a PAGE-Western blot assay. These measurements will reveal the magnitude of oxidative damage in exposed birds and whether their antioxidant barrier responded following oil contamination. Additionally, we will quantify the expression of jun, a proto-onco gene linked to cardiac enlargement and congenital heart anomalies, using qPCR analysis. We hypothesize that sparrows from oiled plots will exhibit higher levels of ROMs and protein carbonyls, and lower levels of GSH and antioxidant barrier strength in tissues. We also expect higher jun expression in cardiac tissue of sparrows from oiled plots. This could provide evidence of a direct toxic effect from food web-linked DWH oil exposure in the seaside sparrow.