Advisory Committee Chair
Robert Angus
Advisory Committee Members
William Howell
Coral Lamartiniere
Douglas Watson
Stephen Watts
Document Type
Dissertation
Date of Award
2007
Degree Name by School
Doctor of Philosophy (PhD) College of Arts and Sciences
Abstract
Estrogenic compounds of anthropogenic origin enter the environment from several different sources, including domestic wastewater and agricultural runoff. Natural estrogens, synthetic estrogens, and estrogen breakdown products have been identified in wastewater treatment plant (WWTP) effluents. These compounds have direct and indirect effects on the endocrine systems of organisms living in the receiving waters. Male mosquitofish (Gambusia affinis) have been suggested as model bioindicator organisms for endocrine disruption by estrogenic compounds for a variety of reasons, including their hardiness, broad environmental tolerances (including temperature, salinity, and dissolved oxygen), widespread geographical distribution, and ease of use in the laboratory. We examined two potential biomarkers of endocrine disruption by estrogenic compounds: variation in sperm counts and the induction of the normally female-limited protein vitellogenin (VTG) in males. We demonstrated that males living below a WWTP effluent exhibited significantly decreased mean sperm counts compared to males living in a reference site, males exposed to a synthetic estrogen in the laboratory had significantly lower mean sperm counts than untreated males, and that there was a significant negative correlation between mean sperm count and dose of synthetic estrogen. We also examined aniii nual sperm counts in males living in an undisturbed environment and found that there was no significant variation in monthly mean sperm counts. However, data analysis demonstrated that mean sperm count showed a significant positive correlation to water temperature. Finally, we demonstrated that there is significant effect of temperature on the amount of VTG mRNA and protein produced by males exposed to a synthetic estrogen in the laboratory.
Recommended Citation
Melvin, Paul D. III, "Sperm Production And Vitellogenesis As Biomarkers Of Endocrine Disruption In The Male Western Mosquitofish, Gambusia Affinis" (2007). All ETDs from UAB. 3762.
https://digitalcommons.library.uab.edu/etd-collection/3762