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theses

Perfluorooctane sulfonate (PFOS), perfluorononanoic acid (PFNA), and perfluorooctanoic acid (PFOA) are all members of the anthropogenic and persistent perfluoroalklyated class of compounds (PFASs). These compounds have similar structures and have been commonly grouped together in toxicity, treatment, and disposal analyses. It was hypothesized that PFOS, PFNA, and PFOA would result in similar toxicity profiles throughout different life stages of zebrafish (Danio rerio). Zebrafish were exposed from 3-120 hours post fertilization (hpf) and endpoints of morphometrics, behavior, and gene expression were analyzed at 5 dpf, 14 dpf, and 6 months (adults). At 5dpf, all PFASs resulted in gene expression changes of transforming growth factor tcf3a and adaptor protein ap1s1 and all fish were smaller size. PFOS exposed fish had the greatest number of endpoint and gene expression changes. At 14 dpf, all PFAS exposed fish showed hyperactivity and increased organic ion transporter slco2b1 expression. All other endpoints analyzed at these time points varied between PFASs. In adult fish, PFNA males were the most affected in behavior but all three PFASs resulted in gene expression changes in slco transcripts. Adult fish chronically exposed to PFOA had reproductive and fecundity affects, including reduced egg production, morphometric effects, and delayed development of the offspring. Chronic PFNA exposure had similar but less severe effects, and PFOS exposure resulted in P0 affects but no immediate reproductive changes. The null hypothesis of this dissertation was rejected at each time point and exposure; PFOS, PFNA, and PFOA exposure resulted in dissimilar toxicity profiles between compounds. The development age of the fish and the endpoints assessed determine which compound was having the greatest effect. In acute embryonic studies PFOS appeared to have the greatest effect. PFNA, in particular the males, are the most affected at the adult stage in terms of behavior. PFOA shows the greatest negative effects on reproduction after a chronic exposure. Additionally, multiple pathways such as ap1s1, slco and tgfb1a were identified as affected by PFASs and further studies are needed to determine if these altered genes during development and maturation may underlie the mechanism(s) of action for these compounds.

ETD_7536

Ph.D.

Includes bibliographical references

by Carrie Jantzen

doi:10.7282/T31G0PJP

ETD doctoral

The author owns the copyright to this work.