Selected Research Projects

Microbiology students are engaged in undergraduate research projects in many departments across the OSU campus. Several past and present representative projects are listed below. 

Megan Reifenberg is studying the role of the HIV-1 promoter’s role within in utero mother-to-child transmission, with Dr. Jesse Kwiek. The researchers are isolating the promoter regions of HIV-1 variants and sequencing them. In order to identify specific mutations which help or hinder transmission, they are searching the promoter genotypes for commonalities between variants which successfully crossed the placental barrier versus similarities between those variants which did not. In addition, they are studying the variants’ activity within host placental cells to allow correlation between phenotypic activity and genotypic mutations in the HIV-1 promoter. This research could provide insight into prevention of in utero mother-to-child transmission.

Alexander Chaitoff is investigating the S box riboswitch, which responds to S-adenosylmethionine, with Dr. Tina Henkin. Riboswitches are RNA elements that directly sense regulatory signals; binding of the signal molecule (in this case, SAM) results in a change in the RNA structure that impacts gene expression. Alexander is generating mutations in a conserved sequence in a Bacillus subtilis S box riboswitch, and will test the effect of these mutations on gene regulation.

Victoria Mason and Colleen Nackerman are studying the molecular mechanisms evolved by the food-borne pathogen, Listeria monocytogenes, to enter and multiply within human cells, with Dr. Stéphanie Seveau. They are using classical tools of cellular biology and fluorescence microscopy to determine the role of the L. monocytogenes pore-forming toxin, listeriolysin O, in the subversion of the host signaling networks during the intracellular life cycle of the bacterium.

Zach Kozel has been studying transcriptional fidelity, which is essential for the faithful gene expression, with Dr. Irina Artsimovitch. RNA polymerase occasionally makes mistakes during RNA synthesis, and accessory proteins may help the enzyme to correct these mistakes. Zach has constructed several in vivo reporter cassettes and tested the effects of the transcription factor DksA protein and mutations in RNA polymerase on transcriptional errors in Escherichia coli

Sarah Repasky recently completed an Honor thesis with Dr. Michael Ibba, in which she studied how quality control helps the cell to accurately translate the genetic code.  Her experiments were focused on comparing the protein synthesis machinery in two different compartments, the cytoplasm and mitochondria.  Her work was part of a study that showed how the cell places different requirements on the accuracy of translation in different compartments and under different growth conditions, which has important implications for our understanding of several neurodegenerative diseases. Sarah is co-author on a recently published paper describing this study.

Emily Wong was working with Dr. Venkat Gopalan (Dept of Biochemistry) to reconstitute RNase P, a universal and essential catalytic ribonucleoprotein responsible for processing of precursor tRNA transcripts from Methanobrevibacter smithii, the predominant archaeon in the human gut. To reconstitute a functional RNaseP in vitro from its constituent subunits, Emily has cloned the genes encoding the single RNA and five protein subunits, expressed them in E. coli, and purified to homogeneity. For her work, Emily has won a poster award at 2010 Denman Undergraduate Research Forum and been named a 2009 Beckman Scholar.

Adrienne Strong has assisted in investigating the role of lung surfactant protein A (SP-A) in the regulation of macrophage immune signaling with Dr. Larry Schlesinger (CMIB). SP-A up-regulates the expression of several immunologically relevant receptors including the mannose receptor (MR), toll-like receptors (TLR) and the scavenger receptor A. Her work has helped to identify an inhibitory effect of SP-A on TLR2 and TLR4 signaling in macrophages and implicated up-regulation of interleukin-1 receptor-associated kinase M (IRAK-M) by SP-A as an important mechanism for inhibition of pro-inflammatory responses.
 
Huy Nguyen is assisting in investigating the role of the peroxisome proliferator-activated receptor gamma (PPARg) in inhibition of macrophage immune responses following infection by Mycobacterium tuberculosis (M.tb) with Dr. Larry Schlesinger (CMIB). PPARγ expression and activity down-regulates pro-inflammatory responses in macrophages and has been shown to be increased by exposure to SP-A and following infection by M.tb. He is investigating the changes in cytokine production and intracellular signaling following knockdown of PPARγ in human macrophages.
 
Robert Bonacci is assisting in investigating the mechanisms behind regulation of M.tb cell wall synthesis by the genes in a putative M.tb operon with Dr. Larry Schlesinger (CMIB). These genes encode for enzymes in the GDP-mannose biosynthesis pathway involved in production of the M.tb cell wall glycolipid mannosylated lipoarabinomannan (ManLAM). ManLAM is an important immunogenic component involved in M.tb pathogenesis. He is currently cloning genes in the operon for use in experiments testing their function in a heterologous expression system.
 

Awards

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