Year of Publication

2011

Season of Publication

Fall

Paper Type

Master's Thesis

College

College of Arts and Sciences

Degree Name

Master of Science in Biology (MS)

Department

Biology

First Advisor

Dr. Kelly Smith

Second Advisor

Dr. Jim Gelsleichter

Third Advisor

Dr. Courtney Hackney

Department Chair

Dr. Courtney T. Hackney

College Dean

Dr. Barbara A. Hetrick

Abstract

Hypoxia in coastal estuaries is a topic of increasing concern, as the magnitude and frequency of hypoxic events have increased over the past several decades. These hypoxic events are highly detrimental to the coastal biota, particulary fish. The hypoxia-inducible factor 1α (HIF-1α) protein was used as a candidate biomarker for deciphering exposure of fish to hypoxic events. In chapter one, Spot (Leiostomus xanthurus) were exposed to three treatment groups of DO (means 7.32 ± 0.18, 5.15 ± .37, and 2.57 ± 0.01 mg Lˉ¹ DO) and sampled (n = 5) at time zero, 36 and 72-h for each treatment. The results of the laboratory trials suggested that duration had a significant effect (F = 28.9, p < .001) on concentration of HIF-1α protein, however, the DO treatment group did not have a significant effect (F = .739, p = .546) on the concentration of HIF-1α protein. L. xanthurus were also analyzed for HIF-1α from field sites of varying DO concentrations (7.0, 5.2, 4.8, and 3.3 mg Lˉ¹ DO), with no significant differences (F = 1.621, p = .208) between sample sites, and with a negative relationship between DO and HIF-1α protein (p = .197) from these sites. Leiostomus xanthurus were exposed to either constant or diel-cycling hypoxia, and HIF-1α expression was compared to normoxic control over three days. The results indicated that HIF-1α protein significantly (p = 0.02) increased in muscle tissue after three days exposure to both constant and a simulated diel-cycling hypoxic event in a laboratory setting when compared to normoxic control animals. It was also found that body mass (measured in wet weight, grams) was a significant covariate for the concentration of HIF-1α produced under normoxia (p = 0.04) and constant hypoxia (p = 0.03), but did not affect the diel-cycling (p = 0.83) groups, suggesting that body mass is a confounding factor when measuring HIF-1α. The correlation of HIF-1α with body mass is likely due to the different tolerances to hypoxia between small and large young-of-year L. xanthurus, an effect that was possibly overshadowed by the acclimation response under diel-cycling hypoxia.

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