Date of Award

8-31-2026

Document Type

Open Access Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Marine Sciences and Technology

First Advisor

Helen C. Poynton

Abstract

Environmental pollutants can disrupt normal developmental processes, leading to neurobehavioral and developmental abnormalities. Toxicity tests are important for evaluating environmental contaminants; however, standard assays are often time- and cost-intensive and typically require large numbers of vertebrate animals. These limitations highlight the need to reduce reliance on vertebrate testing and to develop New Approach Methodologies that provide comparable results while improving efficiency and cost-effectiveness. This research utilizes a novel screening assay to evaluate developmental toxicity using Hyalella azteca. H. azteca is a freshwater amphipod widely used as a model organism for sediment toxicity in ecotoxicology, yet its embryos have been minimally studied. Here, H. azteca embryos are used to develop the Crustacean Embryo Toxicity (CET) assay and evaluate its performance across multiple contaminant exposures. Contaminant exposures include known teratogens such as ethanol and lead, common organic contaminants including butyl benzyl phthalate and benzo(a)pyrene, and air pollution samples from Vieques, Puerto Rico. The CET assay evaluates three primary endpoints: morphology, neurobehavior, and gene expression of key developmental genes. Morphological impacts varied across contaminants, with ethanol producing the most pronounced abnormalities, including incomplete limb development and digestive defects. Gene expression analysis focused on conserved genes, such as orthodenticle (otd), and neurobehavioral assessments also revealed contaminant-specific behavioral alterations. Overall, this study develops a high-throughput, non-vertebrate assay for screening environmental contaminants for developmental toxicity.

Comments

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