Author

Diane D. Chen

Publication Date

2014

Document Type

Honors Thesis

Department

Biological Sciences

Keywords

Oil spills-Environmental aspects-Mexico, Gulf of, Oil spills and wildlife-Mexico, Gulf of, Zebra danio-Effect of oils spills on, Teratology, Developmental biology, Neural crest, Wnt genes, Polycyclic aromatic hydrocarbons-Physiological effect, Neural receptors, Barresi, Deep Water Horizon, Oil spill, PAH, AHR, Wnt, Zebra danio-Embryos-Effect of water quality on

Abstract

On April 20th 2010, the Deepwater Horizon (DWH) oil platform sank, triggering the release of 4.93 million barrels of oil into the Gulf of Mexico from 5000ft below. Concerns have been raised about the effects of crude oil on marine flora and fauna in the Gulf especially those exposed to such toxin during embryonic stages. Examination of native Gulf species is challenging, but the zebrafish provides a tractable model system to directly test the teratogenic effects of crude oil toxins. We investigated the effects of the water accommodated fraction (WAF) of crude oil on zebrafish embryogenesis, and observed cardiovascular and craniofacial malformations that we postulate could be the result of impaired cranial neural crest cell development. Analysis of the DWH oil showed the presence of polycyclic aromatic hydrocarbons (PAHs) and BTEX compounds (benzene, toluene, ethylbenzene, and xylene). We hypothesized that PAHs could also cause similar defects observed in crude-oil mediated teratogenesis. Using a candidate approach, we exposed zebrafish to the 16 PAHs designated priority pollutants by the EPA, and all yielded a similar disappearance of the 6th pharyngeal arch. From our experiments, pharyngeal arch malformation is most likely due to a defect in cranial neural crest migration and not cell survival. Previous studies have shown that PAHs activate the aryl hydrocarbon receptor (AhR) signaling pathway. In my study we investigated whether cross talk between the AhR signaling pathway and canonical Wnt signaling functions as the molecular mechanism to mediate potential neural crest malformations following exposure to PAHs. We found that naphthalene was able to induce AhR signaling activation and the noncannical Wnt signaling pathway as a promising component in the molecular mechanisms mediating PAHteratogenesis. Understanding the molecular mechanisms that mediate interactions between the environment and embryo will provide insight into both the regulation of developmental plasticity as well as the risks present in our own environment.

Language

English

Comments

102 pages : color illustrations. Honors Project, Smith College, 2014. Includes bibliographical references (pages 91-101)

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