The Texas horned lizard (Phrynosoma cornutum) is considered a threatened species in Texas and Oklahoma, due to substantial range declines over the past several decades. Horned lizards are believed to be highly vulnerable to habitat alterations, due to extreme specialization on ants, particularly harvester ants (Pogonomyrmex spp.). I analyzed diets of Texas horned lizards from two small towns by identifying exoskeletons of prey items found in fecal pellets. I assessed dietary specialization by comparing diet to prey availability, based on pitfall traps and abundance of harvester ant colonies. My results found strong spatio-temporal variation with respect to prey abundance and consumption. Harvester termites (Tenuirostritermes cinereus) and big-headed ants (Pheidole spp.) accounted for over 70% of all prey consumed. Average consumption of big-headed ants was comparable to their abundance in pitfall traps, but consumption of harvester termites was much higher than their pitfall trap abundance. Consumption of harvester ants is strongly correlated with the number of harvester ant colonies within study sites and horned lizard home ranges. Dietary diversity and richness were positively related to the area of dense vegetation in sites and lizard home ranges. These results suggest horned lizards in these towns adjust diet in relation to prey availability, which is considered a characteristic of generalist predators. The superior nutritional value of harvester termites relative to similarly sized ants could explain the apparent lack of size-based prey preference in these horned lizard populations.

Exposure to contaminants during development has the potential to cause adverse biological alterations that can persist through depuration periods and into adulthood. This study examined the effects of chemically induced, early-life-stage thyroid disruption on endpoints associated with thyroidal and reproductive function in the fathead minnow (Pimephales promelas). Fish were exposed to propylthiouracil (PTU) from 1 to 43 days post hatch (dph) to induce hypothyroidism. At the end of exposure, length and weight were measured and samples were taken for gene expression analysis. The remaining fish were transferred to un-dosed water and raised to maturity and, at 164 dph, a 21-day breeding assay was performed. At the end of exposure, fish exposed to PTU had significantly reduced length and weight indicating successful thyroid disruption. There were also significant differences in expression of several genes involved in the thyroidal and reproductive signaling systems. After maturation, there were no significant differences in any morphological variables. During the 21-day breeding assay, fish from the PTU exposure group had significantly reduced overall fecundity relative to controls. Based on data collected so far, it appears that this reduction in fecundity is due to either ovarian dysfunction or alterations in reproductive behavior. The results show that early-life-stage hypothyroidism can affect reproductive function later in life even after thyroid related endpoints have returned to control levels.

Hepatitis C Virus is estimated to infect 3% of the world’s population and is transmitted by contaminated blood. HCV can be asymptomatic or lead to cirrhosis of the liver, liver cancer or hepatocellular carcinoma. Understanding the virus life cycle and the viral proteins generated by HCV will help generate new mechanisms of inhibition of the virus. HCV produces 10 viral proteins when it infects hepatocytes that increase the reproduction ability of the virus. The anti-viral response of the body uses transcription factors such as ATF-2, NFKB, and IRF-3 that translocated into the nucleus and bind to the interferon gene that produces interferon to alert the body of a viral infection. HCV viral protein NS3/4A acts as protease to cleave the polycistronic strand of viral proteins made by HCV and is known to inhibit IRF-3 movement into the nucleus to inhibit the production of interferon. HCV viral protein NS5A is known to inhibit the movement of transcription factor NFKB into the nucleus, thus inhibiting the anti-viral response. We are interested to see if NS3/4A inhibits the anti-viral response by blocking the movement of both transcription factors IRF-3 and NFKB into the nucleus.

Psychological stress afflicts a considerable portion of the world’s population, and is linked, as both a risk factor and potential contributor, to dementia-related brain dysfunction in diseases such as Alzheimer’s disease (AD). The brain dysfunction in AD is marked by an increase in Amyloid-beta, the protein responsible for plaque deposition in the brain. The present study aimed to explore alterations in the production of amyloid-beta in response to stress and inflammation. Specifically, we were interested in social isolation stress- and inflammation-induced differences in cognition and amyloid-beta production in male and female mice. Mice were subjected to acute social isolation (6 days) and chronic isolation (28 days) or control group housing. Results revealed that exposure to both acute and social isolation can lead to an exacerbated inflammatory response to lipopolysaccharide (LPS). Subsequently, we examined if the stressors altered amyloid-beta production following the same inflammatory stimulus. Animals received LPS or saline injections once per day for seven consecutive days after the completion of either stress protocol or group housing. The contextual fear conditioning paradigm (CFC) was utilized to assess cognition. Brain tissue extractions were performed to quantify amyloid-beta protein levels. It is hypothesized that isolated animals will demonstrate cognitive deficits in CFC as well as increased brain amyloid-beta following LPS injections.

Mercury (Hg) is a toxic heavy metal that has contaminated all aquatic food webs and can pose a health risk to aquatic predators. Piscivorous birds are apex predators in aquatic systems that are exposed to mercury through the consumption of Hg-contaminated fish. Although there is extensive data on Hg concentrations in fish, the data on Hg concentrations in birds is relatively limited. I used a previously published relationship between Hg concentrations in piscivorous bird blood and Hg concentrations in prey fish to estimated Mg concentrations in the blood of four species of piscivorous wading birds in the south central U.S. [Little Blue Herons (Egretta caerulea), Green Herons (Butorides verescens), Great Egrets (Ardea albus) and Great Blue Herons (Ardea herodias)] from the concentration of Hg found in bluegill (Lepomis macrochirus). Estimated Hg concentrations in bird blood increased with the size of prey fish consumed and was lowest for Little Blue Herons and Green Herons, intermediate for Great Egrets and highest for Great Blue Herons. Estimated Hg concentrations in bird blood was greatest in ecoregions where conifer-adjusted mercury deposition was highest. Mercury risk to bird health varied with bird species and increased with Hg deposition. Little Blue Herons, Green Herons, Great Egrets and Great Blue Herons were at some level of risk in 14, 36, 86 and 100% of ecoregions, respectively. The threat of Hg to the health of piscivorous wading birds may not be unique to south central U.S. and may extend throughout the southeastern United States due to high Hg deposition and extensive forest coverage.