Shipyard Creek gene expression in 2003

We used the mummichog (Fundulus heteroclitus) array we developed to test whether our arrays could be used to monitor the efficacy of remediation at an estuarine Superfund site. Shipyard Creek is a chromium-contaminated Superfund site in Charleston, SC undergoing remediation, therefore it provides a unique opportunity to study the efficacy of arrays as a molecular biomarker in of toxicant effects in mummichogs. Mummichogs were captured in Shipyard Creek in Charleston, SC prior to remediation (2000), after remediation began (2003), and as remediation further progressed (2005). Simultaneously, mummichogs were collected from a reference site at the Winyah-Bay National Estuarine Research Reserve (NERR). The hepatic gene expression pattern of fish captured at Shipyard Creek showed wide differences from the fish captured at NERR in 2000. As remediation progressed the gene expression pattern of fish captured at Shipyard Creek became increasingly similar to fish captured at NERR, and the number of genes differently expressed dropped from 22 to 4. The magnitude of differential gene expression of the individual genes also decreased during remediation. The recovering gene expression profile is associated with lower chromium bioavailability, demonstrated through significantly decreased body burden and sediment concentrations. For example, sediment concentrations at Shipyard Creek were 80-fold greater than NERR in 2000, 51-fold greater in 2003, and only 8-fold greater in 2005. However, hydraulic dredging in 2005 stirred up the sediments and increased body burden of chromium even though chromium sediment concentrations continued to drop. Therefore, the number of differentially expressed genes increased to 9. Overall, the data supports our hypothesis that arrays can be used to monitor site mitigation, as the number of genes differentially expressed mimics the body burden and also indicates when on-site remediation is increasing bioavailability. Keywords: Field site Shipyard Creek is a chromium contaminated Superfund site in Charleston, South Carolina (USA) that was added to the NPL list in 1998 because of increasing chromium contaminated in the nearby estuary. The site began remediation in early 2003. Mummichogs were collected using baited minnow traps from Shipyard Creek (1) before remediation began in 2000, (2) during remediation in 2003, and (3) as remediation neared completion in 2005. Mummichogs were also collected from the reference site at North Inlet National Estuarine Research Reserve (NERR) in 2000, 2003, and 2005. Mummichogs were euthanized immediately after collection, livers excised, and placed in TRI-Reagent« for RNA isolation (Sigma Chemical Co, St. Louis, MO). Samples were then snap frozen in liquid nitrogen, mailed to UTEP on dry ice, and stored at -80C for array analysis. (n = 7)