PARENT SESSION

PM06 Linking Aquatic Toxicology with Ecosystem Indicators
Exhibit Hall
8:00 AM - Monday, 10 November 2003

(PM124) Exogastrulation in sea urchin embryos as a biomarker of contaminant exposure in the aquatic environment.

Vines, C.¹, Higashi, R.², Anderson, S.¹, Cherr, G.^{1, 2}, ¹ Bodega Marine Laboratory, University of California, Davis, Bodega Bay, CA, USA² University of California, Davis, CA, USA

ABSTRACT- Polycyclic aromatic hydrocarbons (PAHs), many of which are known to be cytotoxic, carcinogenic, and mutagenic, and phthalates, which are known to have estrogenic potential, are common contaminants of aquatic environments that are of increasing concern due to their effects on aquatic organisms. We have recently found that exposure to creosote, a commonly used wood preservative containing a number of PAHs, and dibutyl phthalate (DBP) causes a specific defect during sea urchin development that results in exogastrulation (evagination of the archenteron), which is morphologically identical to that caused by exposure to lithium, a known vegetalizing agent. The effects of lithium and PAHs are stage-specific, PAHs being more potent than lithium at the ciliated blastula stage, while lithium is more effective post-fertilization. DBP does not appear to be stage-specific, as equal numbers of exogastrulae are observed at both the post-fertilization and ciliated blastula stages. Exogastrulation of sea urchin embryos is associated with nuclear accumulation of -catenin, a protein involved in cell specification during development via the Wnt/Wg signaling pathway. We are investigating the use of the sea urchin embryo assay as a biomarker in evaluating the potential toxicity of sediments collected from contaminated estuaries as well as in situ exposures in local marinas. Our preliminary results indicate that exposure to sediment elutriates contaminated with phthalates results in exogastrulation similar to that seen in embryos exposed to creosote, individual PAHs, and DBP. Embryos cultured in close proximity to a creosote-treated piling in a marina also exhibited a high percentage of exogastrulation as compared to control embryos. We plan to expand our investigation of estuarine environments utilizing exogastrulation in the sea urchin embryo as a biomarker of exposure to PAHs and phthalates. Supported by U.S. EPA, Pacific Estuarine Ecosystem Indicator Research Consortium (PEEIR), STAR EaGLes Program.

Key words: Sea urchin, Exogastrulation, PAHs, phthalates