Date of Award

Spring 5-21-2018

Department

Biology

First Advisor/Professor

Carolyn S. Bentivegna, Ph.D.

Second Advisor/Professor

Liping Wei, Ph.D.

Third Advisor/Professor

Heping Zhou, Ph.D.

Abstract

Environmental pollution is of great concern in the United States. Of special concern is the chronic effects from the exposure to potentially carcinogenic compounds released from episodic environmental disasters (e.g. 911 twin-towers, oil spills). Disasters like the British Petroleum (BP) Deepwater Horizon oil spill in the Gulf of Mexico (GOM), affected many marine organisms, exposing them to crude oil polycyclic aromatic hydrocarbons (PAHs), some of which are known carcinogenic. Despite many marine-based consumer products (e.g. fish oil, animal feed, fertilizer) were known affected by the BP oil spill, bioaccumulation and chronic toxicity of the crude oil PAHs into marine organisms and overall wellbeing of marine organisms after the BP Deepwater Horizon oil spill are not fully understood.

In this study, Gulf Menhaden (Brevoortia patronus), one of the most important fish species in the consumer products named above, were studied. Wild Gulf Menhaden were caught from Vermilion Bay, Louisiana (VBLA) and Grand Isle, Louisiana (GILA) in 2012 and 2013. The menhaden were dissected and the tissue/organs were analyzed for crude oil PAHs via Excitation Emission Matrix Spectroscopy (EEMS) and 2D Fluorescence Spectroscopy. Genomic DNA was extracted from various fish tissue/organs, and was analyzed for polymorphisms in tumor suppressor gene p53 DNA binding region (DBR) using PCR-SSCP (Polymerase Chain Reaction-Single Stranded Conformational Polymorphism) and in cloning-sequencing. The fish was also measured for body length and weight, which were used to evaluate its age and age-appropriate development.

PCR-SSCP results revealed polymorphisms of p53 DBR in more than 50% of the menhaden individuals. The polymorphism was also tissue/organ dependent, and was greater in liver and gill than in muscle, heart or gonad. The DNA cloning/sequencing result suggested menhaden p53 DBR diverged with low level of missense mutation in the exons and multiple substations and insertion or deletion in the intron of p53 DNA binding region which may affect gene splicing. The resulting p53 variants may or may not be functional.

EEMS and 2D Fluorescence Spectroscopy scans revealed crude oil PAHs in all fish samples. The preliminary data suggest more crude oil PAHs (normalized to tissue/organ fresh weight) in the liver and gonad than gill, and that the low molecular weight PAHs were preferentially metabolized in all liver samples, with some showing more in-depth metabolism than the others.

Gulf Menhaden body length and weight did reveal developmental abnormalities and potentially abnormal single stranded p53 DBR hairpins from cloning-sequencing within the given data. Additional work is needed to increase the sample size, which may further strengthen the preliminary observations in each of the three aspects of this study. Future work may further elucidate the functionality of P53 variants in Gulf Menhaden, and evaluate the long-term bioaccumulation and metabolism of crude oil PAHs to answer questions like “do the fish die prematurely from crude oil body burden, and what tolerances might Gulf Menhaden have to crude oil and crude oil derived PAHs?”

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