Determining the Role of Sox9 in Paneth Cell Populations

Michael Cronce

Research Advisor:  Dr. Scott T. Magness
Biology Sponsor: Dr. Jason Lieb

The intestinal epithelium is a highly proliferative tissue that self-renews every 7-10 days. Self-renewal is driven by intestinal epithelial stem cells (IESCs) marked by Sox9, a transcription factor shown to play an important role in the proliferation, maintenance, and differentiation of IESCs. Studies have reported Sox9 to be both necessary for the generation of and expressed in Paneth cells, a cell lineage that provides antimicrobial defense for the intestines. Interestingly, our data show that Sox9 protein is expressed in only half of the Paneth cell population. Considering that the IESC’s from which the Paneth cells develop express Sox9 protein, we hypothesized that the presence of Sox9- Paneth cells could be explained by a slow rate of Sox9 degradation as the Paneth cell differentiates and matures. To test this hypothesis, immuno-histochemical staining and a cell birthdating technique were used to determine whether Sox9 protein expression correlates with the age of the Paneth cell. We predict that younger Paneth cells would express Sox9, while older Paneth cells would not.

Inhibiting the Relaxase Domain of the DNA Helicase TraI

Diane Esson

Research Advisor:  Dr. Steve Matson

Bacterial conjugation is a common phenomenon within the microbial world that enables the exchange of genetic material between bacteria. The horizontal transfer of extrachromosomal plasmid DNA is a major contributor in the vast and devastating spread of antibiotic resistance. This process relies on numerous proteins, including a DNA helicase known as TraI, which cleaves and religates transferred DNA. It has been noted in previous works that the active site of TraI necessary for these enzymatic reactions, referred to as the relaxase domain, looks structurally susceptible to inhibition by biphosphate molecules. My research seeks to test the ability of various biphosphates to suppress conjugation. This is being tested both on a molecular scale with regard to TraI activity, and on a cellular level, by monitoring interference with the transfer of antibiotic resistance plasmids between bacteria. If successful, this inhibition may prove a plausible solution for reducing the spread of antibiotic resistance.

The Ability of Loggerhead Sea Turtles, Caretta caretta, to Navigate Using a Magnetic Field

Sarah Reintjes-Tolen

Research Advisor:  Dr. Kenneth Lohmann

Loggerhead sea turtles, Caretta caretta, navigate great distances of featureless open ocean throughout their lives, often returning to their natal beaches as adults to breed and nest.  The exact mechanisms loggerheads use to achieve this impressive feat are unknown.  This research was performed to determine if they utilize the Earth’s magnetic field for orientation.  In order to determine how loggerheads achieve this difficult task juvenile loggerheads were placed in an artificial magnetic field with a specific angle intensity and inclination goal.  The turtles participated in trials to determine if they possess the ability to recognize and navigate toward specific magnetic coordinates.  The issue of whether juvenile loggerheads possess the ability to navigate and create an internal magnetic map thereby utilizing an innate GPS system remains an issue of interest and contention.  These studies will aid in tracking navigational routes of loggerhead sea turtles to aid in conservation of the species.

Modulation of the Effectiveness of Anti-Microtubule Agents by Microtubule Associated Proteins

Greg Schimizzi

Research Advisor:  Dr. Donita Robinson
Biology Sponsor: Stephen Rogers
Research Mentor: Josh Currie

Chemotherapeutic cancer treatments often target the microtubule cytoskeleton to disrupt cancer cell mitosis and proliferation. Recent evidence suggests that microtubule associated proteins (MAPs) may be involved in drug-induced microtubule depolymerization. Using a combination of RNA interference in Drosophila S2 cells, immunofluorescent high-throughput microscopy, and time-lapse video microscopy, we identified a specific MAP, Kinesin-Like protein 10A (KLP10A), which appears to impact the efficacy of the anti-microtubule drug colchicine. KLP10A is known to have a role in depolymerizing microtubules in both mitosis and interphase cells. We found that depletion of KLP10A in S2 cells confers a resistance to colchicine depolymerization. Likewise, overexpression of KLP10A-GFP results in increased susceptibility to drug treatment. These findings suggest that expression levels of the human homologue of KLP10A may be an attractive biomarker to assess the effectiveness of anti-microtubule chemotherapies.