Research Presentations - 2009-10
John Deere Chapter of Sigma Xi

6:30 - 8:30 pm, Tuesday, January 19, 2010
Science Building, Augustana College, Rock Island, Illinois

New associate members of the chapter are invited to present either a 10 minute talk or a poster that describes the research that they have been doing.  Here is the online form for submitting the abstract.  The deadline is Friday, Jan. 15, 2010.

Below is the list of talks and posters that will be presented by the new associate members of the chapter inducted on Nov. 17.

This page will evolve into the official program for Jan. 19 in that it will include the schedule of talks, the descriptions, list of posters and their descriptions.  During the evening, the posters will be on display in the Atrium of the Science Building.  The students displaying posters will be introduced after the final talk.  Then, in the Atrium, we will have refreshments, view the posters, and enjoy conversation with all of the presenters.

Ypt11p is a small, Rab-type GTPase in S. cerevisiae. Although Ypt11p is known to positively affect both mitochondrial and endoplasmic reticular inheritance in budding cells, its cellular localization is still unclear. In this study, a high expression vector was constructed to express GST-tagged Ypt11p in E. coli. Additional expression studies were performed with this vector to determine the effects of temperature, concentration of the inducer IPTG and time of growth after induction on the expression level of the protein. Solubility tests suggest that, while much of the expressed Ypt11p is insoluble, ~20% of the protein is soluble under certain growth conditions. Preliminary GST affinity chromatography purification reveals that the expressed Ypt11p can be enriched. The next step in this project is to express and purify milligram amounts of modified Ypt11p for production of polyclonal antibodies to be used in immunolocalization experiments.

Bacterial infections are a major cause of human illness. Past studies have shown that chemicals, such as hormones, can have a large impact of the expression of virulence genes in bacteria, making those bacteria more harmful to humans. The proposed study is designed to investigate the effects of the human hormones epinephrine and norepinephrine on the methylation of virulence genes in Escherichia coli. These hormones have been shown to influence the expression of virulence genes. Methylation is an epigenetic mechanism that aids in the regulation of gene expression and could therefore be responsible for these changes in gene expression. In order to observe whether the hormones impact methylation, wild-type E. coli strain K12 (MG1655) and E. coli strain ER2925 that lacks the ability to methylate DNA substrates will be used.

The study was conducted in a duckweed-dominated urban riparian marsh along the Rock River. To study the effects of duckweed removal, enclosed experimental chambers were placed in the wetland and duckweed was removed from half of them. Shortly after the treatments were established, the pH of treatments with no duckweed began to increase. On some days, the difference between the pH of the two treatments was significant, perhaps due to an increased consumption of dissolved CO2 by primary producers in the water. Some of the treatments with no duckweed showed signs of significant algal growth, likely a result of less competition within the chamber. Higher levels of dissolved oxygen accompanied the growth of algae in some of the chambers. An effect of duckweed on nitrification or nitrifying bacteria populations was not demonstrated. This may be a result of constraints on the experiment or the heterogeneous environment of the marsh.

During the summer of 2009 I was hired for a research program at Augustana College. The research required me to construct a plasmid for use in later experiments as a template for inserting mutations into S. cerevisiae for further study in mitochondrial inheritance.

Glutamate dehydrogenase (GDH) is an important enzyme that helps in many organisms’ metabolism and waste removal. GDH2, a type of glutamate dehydrogenase, coverts the amino acid glutamate into alpha ketoglutarate, an intermediate in the citric acid cycle. In order to do further research on this enzyme, studies need to be done on the genes that code for GDH2 in Saccharomyces cerevisiae. Specifically, what happens when the GDH2 gene is nonfunctional? In this study, I created a deletion disruption mutant of the gene GDH2 to further studies on glutamate homeostasis. The GDH2 gene was inserted into the plasmid, pUC18, using restriction enzymes and then cut again to insert an Ura3 marker.

Valeriana officinalis L., commonly known as valerian, is a plant species native to Europe. It has been known to possess sedative and antispasmolytic properties. Recent research has demonstrated that valerian might influence the amplitude of smooth muscle contraction through prevention of calcium ion influx. It is believed that the uterine contractions in the condition of primary dysmenorrhea are caused by the influx of intracellular calcium. It is suspected that an increase in the production and activation of prostaglandin F2α may be the cause of primary dysmenorrhea. Prostaglandins have been linked to an increase in the levels of intracellular calcium, through the IP3 biochemical pathway. In this research, contraction of rat uteri will be stimulated through addition of prostaglandin F2α. It is proposed that valerian extracts will prevent prostaglandin mechanism of action thus, decreasing in intracellular calcium and inhibiting smooth muscle of uterine contraction.

Aminopeptidase N (PepN) is the major aminopeptidase in E. coli and is involved in ATP-dependent down-stream processing during cytosolic protein degradation. The mechanistic role of a glutamic acid (E298) or a tyrosine (Y381) in the PepN active site is being explored through site-directed mutagenesis. Plasmid DNA containing the gene that encodes PepN (pET-26bPepN) was purified from BL21 (DE3) E. coli cells. PCR site-directed mutagenesis created four point mutations: E298D, E298N, Y381A, and Y381F. In addition to a point mutation, the mutagenesis created a silent mutation in the four mutants which introduced a new restriction site. These silent mutations allowed for quick and easy determination of successful mutagenesis. Additionally, a hex-His tag is being incorporated with the PepN gene to aid in protein purification. In future research, these mutants will be characterized through kinetic assays to explore the role of E298 and Y381 in the putative reaction mechanism.