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The Lab Spring 2011
Sam Guffey, Cheryl Chan, Kat Munley, Rachael Heuer,
Andrew Esbaugh, Kevin Brix, Martin Grosell
Andrew Esbaugh (aesbaugh@rsmas.miami.edu)
To date, my research has used a combination of biochemical and molecular approaches to answer questions pertaining to the mechanisms and evolution of physiological systems in vertebrates. I am also interested in how sub-lethal exposure to various heavy metals (primarily lead and copper) may affect physiological systems under non-steady state conditions. I am currently involved in several studies at the University of Miami. The primary study I'm involved with is a validation study of the biotic ligand model for lead, whereby the effects of water chemistry on lead toxicity are assessed and compared to those predicted by the lead biotic ligand model. This study is being performed on four different species using natural waters of vastly different chemistries from 7 sites around North America. I am also involved in a second study examining the mechanisms of calcium uptake and calcification in the freshwater snail, Lymnaea stagnalis, especially as they pertain to early development, as well as how variable calcium levels, and environmental agonists (lead) may affect this process.
Ed Mager (emager@rsmas.miami.edu)
My research is focused on examining the acute and chronic effects in commercially important pelagic fish species that result from exposure to polycyclic aromatic hydrocarbons (PAHs), the primary class of toxic agents released from oil. Specifically, I intend to characterize the PAH concentrations that cause acute mortality during the most sensitive early life stages (i.e. embryonic and larval), as well as examine the long-term effects of PAH exposure by evaluating various physiological parameters. Previous research has shown that PAHs affect cardiac development and may cause anemia. These effects would likely impair the ecological fitness of fish populations by reducing swimming performance (e.g. by affecting migration, foraging and/or predator avoidance). I intend to investigate the potential effects on swimming performance and aerobic scope using swim tunnel respirometery, and evaluate impairment to cardiac development utilizing in vivo microscopic morphometrics.
My research interests are in the areas of evolutionary physiology and environmental toxicology. I have conducted a wide range of studies investigating the effects of metals on freshwater and marine organisms and am currently study the effects of Cu and Pb on the freshwater pulmonate snail, Lymnaea stagnalis and the effects of dietary silver exposure on marine invertebrates. My Ph.D. research is focused on evolutionary physiology of the pupfish Cyprinodon variegatus. I am currently investigating differences in ionoregulatory capacity between the coastal form (C. v. variegatus) and a derived inland lake form (C. v. hubbsi) of this fish. C. v. hubbsi has been isolated in several lakes in central Florida for the past ~200,000 years. My research has shown this inland lake form has evolved an ability to acquire Na+ at significantly lower (~two orders of magnitude) ambient Na+ concentrations than the coastal form. I'll be investigating the specific transport mechanisms involved in these observed differences and the molecular evolutionary processes that led to these changes.
http://www.rsmas.miami.edu/personal/kbrix/index.htm
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Recent research has highlighted the formerly understated importance of marine teleost fish to the oceanic carbon cycle. My research interests lie in examining how projected ocean acidification levels will affect acid-base compensatory mechanisms in the gulf toadfish (Opsanus beta). It has already been established that gastrointestinal HCO3- secretion is a vital component of the toadfish osmoregulatory process, a mechanism hypothesized to also play a role in acid-base balance. In my current research project, I am measuring concentration and rate changes of intestinal HCO3- secretion and rectal HCO3- excretion in toadfish exposed to elevated atmospheric carbon dioxide concentrations predicted for the end of the current and next centuries. I am also interested in quantifying changes in carbonate precipitate formation rates, dissolution potential and carbonate chemical composition as a result of hypercapnia.
Marine fish face a suite of physical factors that affect their everyday lives. Most important of these is the high salt content of the oceans and because of this obstacle, fish must not only prevent the loss of water to their environment, but also absorb it efficiently into their bodies. In my research, I study how the effects of osmoregulatory challenges in the toadfish (Opsanus beta) intestine affect their ability to regulate ions and absorb water. I focus on guanylin and uroguanylin, a family of intestinal peptides, which activate the opening of intestinal chloride channels via a receptor-mediated cascade. This mechanism allows chloride ions (and bicarbonate ions) to exit the intestinal cell and enter the lumen of the intestine. The purpose of this study is to determine how guanylin and uroguanylin are transcriptionally regulated when environmental salinity changes. Further experiments will test the effects of varying pH levels in situ on the capability of toadfish to withstand different environmental salinity regimes.
Undergraduate Students
My research focuses on the toxicity of metals to the freshwater pond snail, Lymnaea stagnalis. Previous studies have established L. stagnalis as the most sensitive aquatic species tested to date for Cu and Pb based on 30-d experiments evaluating juvenile snail survival and growth. Despite this high sensitivity, the effects of metals on L. stagnalis when exposed over the full life cycle of the animal are unknown. I am currently investigating the effects of Pb on L. stagnalis in a full life cycle study that will begin with newly hatched snails and evaluate survival, growth, and reproduction as well as survival and growth in the F1 generation. My goal is to pinpoint the time during its life cycle at which L. stagnalis is most sensitive to Pb. I hope to continue studying these organisms in the future and use my research to formulate an undergraduate senior thesis.
