Toxicity Assessment and Effects of Molecular Structure of Naphthenic Acids on Mode of Toxic Action in Lymnaea stagnalis

Date
2017
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Abstract
Naphthenic acids (NAs) are a diverse group of carboxylic acids often associated with the toxicity of tailings, a petrochemical waste product generated by oil sands mining. NAs can be found in the acid extractable organic fraction (AEO) of the liquid component of tailings, oil sands process-affected water (OSPW). To assess the potential toxicity of AEO and individual NAs, a hatching bioassay using imaging and computer analysis was developed using the pond snail Lymnaea stagnalis. AEO dose-dependently decreased Lymnaea hatching percentage as well as delayed hatching at 25-50 mg/L AEO. This study also aimed to assess the effect different NA molecular architectures may have on NA toxicity. Varying degrees of hatching success and hatch time delays were observed following exposure of Lymnaea embryos to individual model NAs with diverse molecular structures. Molecular shape and dipole architecture of NAs may be an important factor in the ability of certain NAs to insert in biological membranes, indicating a possible relationship between NA structure and the degree of severity of NA toxicity. Finally, this study explored the hypothesis that the mechanism of NA toxicity is due to “narcosis” (which involves plasma membrane disruption via insertion of NAs’ hydrophobic alkyl tail) and may work in conjunction with PLA2-mediated fatty acyl hydrolysis. While the data did not support this hypothesis, it uncovered evidence for a hitherto unrecognized biological action of NAs; the binding of fatty acid-binding proteins.
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Keywords
Animal Physiology, Biology--Molecular, Zoology, Toxicology
Citation
Marasco, K. (2017). Toxicity Assessment and Effects of Molecular Structure of Naphthenic Acids on Mode of Toxic Action in Lymnaea stagnalis (Master's thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca. doi:10.11575/PRISM/28491