University of Michigan, biomedical engineering

The goal of the project I worked on in the Sherman lab was the isolation and structural characterization of the asb-encoded Bacillus anthracis siderophore. The isolation was done using a purification technique we devised through some research and trial and error. The structural characterization was done using NMR, mass spectrometry and analytical HPLC experiments.

University of Michigan, biochemistry & mathematical biology

I worked in Dr. Matthews' lab with Dr. Lee Elmore to study the effects of a riboflavin-deficient diet on genetically altered mice with low methionine synthase reductase activity.

Methionine synthase converts homocysteine to methionine, utilizing a methyl group from methylte-trahydrofolate and also forming tetrahydrofolate. Approximately once in every one-thousand turnovers, the cobalamin cofactor of methionine synthase becomes oxidized by molecular oxygen, inactivating it; methionine synthase reductase is required to rereduce the cobalamin cofactor of methionine synthase to the active state. A diet deficient in riboflavin was formulated that would target the reductase, but spare other flavin-dependent enzymes. Mice were separated into three groups and pair-fed either the standard lab chow, the experimental diet with normal riboflavin, or the experimental diet with low riboflavin for three weeks. At the end of the regimen, plasma samples were taken for homocysteine and methionine measurements, and livers were excised for enzyme assays.

The results showed that plasma homocysteine was lowered and plasma methionine was elevated in the mice on the low riboflavin diet as compared to mice on control diets. Other flavin-dependent enzyme activities were approximately normal. These results suggest that methionine synthase reductase levels may be regulated during transcription or translation, and that placing the hypomorphic mice on a low riboflavin diet may cause them to produce more reductase protein.

University of Michigan, chemistry

Shawn Xu's lab studies the genetics of drug dependence using the nematode worm C. elegans as a model organism. We expose worms to nicotine and other drugs of abuse, then track the resulting behaviors with an automated tracking system developed by Dr. John Feng. With the tracking system we can quantify and analyze different parameters of the animals’ behaviors. The different responses to drugs in C. elegans mutant strains allow us to identify genes involved in the drug response. The Xu lab verifies this data by creating and tracking transgenic animals.

Although C. elegans are approximately 1mm long and have less than 1000 cells, their responses to nicotine and other drugs are analogous to that of mammals. The nematodes show signs of acute response, tolerance, withdrawal, and sensitization, the key elements of drug response. The nematode provides indeed an elegant model system for this research, due to their powerful genetics.

It is our aim to continue identifying new genes related to drug dependence, and to learn more about the neural signaling patterns of the drug response. We are confident our research will aid the understanding of drug dependence across species.

Northern Michigan University, biochemistry student

Working closely with Dr. Jeff Kittendorf in the Sherman lab, my summer goal was to make multiple constructs of the Pikromycin Thioesterse II domain and then express and purify these constructs. The purpose of building these constructs was to increase the solubility of the protein with the hopes of growing protein crystals for future structure determination research. A large part of my summer was spent making the constructs using Ligation Independent Cloning. Four of ten successfully cloned constructs were then expressed in E. coli and purified using nickel affinity column chromatography. Further work will consist of expressing and purifying all of the constructs, performing solubility tests, and setting up crystal trays.

Michigan State University, biochemistry

Working in the Ginsburg lab, my hypothesis was that the Asialoglycoprotein receptor is the major receptor involved in clearance of von Willebrand Factor modified by N-acetylgalactosaminyltransferase from blood plasma.

The hypothesis was tested by injecting mice with and without the receptor with either modified or unmodified von Willebrand Factor (VWF) and measuring VWF levels in bleeds taken at various time points.

We could not obtain any conclusive evidence regarding the involvement of the receptor. Further research needs to be done to test that receptor and possibly other receptors that could play a role in clearance.