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Melissa Thompson BS: Biolgical Sciences, Minors: Chemistry & Spanish, University of Missouri - Columbia Oak Ridge National Laboratory |
Description of Research
Mentor(s): Robert Hettich
Rotation Summary
Mentor: Ed Michaud - Fall 2003
Characterization of an Allelic Series of Mutations in the Mc1r Gene in Mice.
The hairs of wild-type mice are black with a subterminal band of yellow. The melanocortin 1 receptor (Mc1r) gene regulates this alternating production of black and yellow pigments in the hair. Dominant mutations in Mc1r result in an increase in black pigment in the hair. Recessive mutations in Mc1r result in a decrease in black pigment and a corresponding increase in yellow pigment in the hair. Here we present the preliminary characterization of five new ethylnitrosourea (ENU)-induced, semi-dominant, hypermorphic mutations in the Mc1r gene.
Mentor: Chris Dealwis - Spring 2004
Interaction between Sml1 and Rnr1 using Fluorescence Spectroscopy.
RNR catalyzes the rate-limiting step of dNTP synthesis in yeast. Sml1 acts as an inhibitor of RNR activity by the action of its C-terminal domain interacting with the Rnr1 binding domain. We use fluorescence spectroscopy to monitor the physical interaction of these two proteins. A fluorescence probe was attached to Sml1 to demonstrate a change in the fluorescence emission when the two proteins are interacting. By this method, we obtained a Kd value for interaction of these two proteins close to the published value.
Mentor: Loren Hauser - Summer 2004
Identification and classification of two putative promoter motifs in Rhodopseudomonas palustrus.
Rhodopseudomonas palustrus has the ability to fix nitrogen under nitrogen-starvation conditions. TGGcacggN3tTGca is the consensus sigma 54 (RpoN) binding site, which regulates nitrogen metabolism genes in bacteria. The NifA binding site (TGTN10ACA) regulates the molybdenum-dependent nitrogenase genes. Here, we describe two more regulatory motifs, GCGN9CGC and TCGN6CGA that were found in some of the genes involved in nitrogen fixation. Using the AlignACE, Phylocon, and promscan algorithms, we were able to discover and locate these two novel promoter motifs.
Mentor: Robert Hettich - Summer 2004
Method Development Toward Characterizing the Complex Metaproteomes of Microbial Communities 'MudPIT for Mud Puddles'.
The next step in studying the proteomics of living organisms is to examine the dynamics of a microbial community. This project used four species of unicellular organisms (R. palustris, S. oneidensis, E. coli, and S. cerevisiae) as a mechanism to develop techniques for studying complex microbial communities. We varied the concentration of R. palustris from 25% to 0% of the mixture in order to test if we could detect a species that was not present in high abundance.
Publications
- Thompson, M. R., Brown, S. D., VerBerkmoes, N. C., Chourey, K., Shah, M., Zhou, J., Hettich, R. L., and Thompson, D. K. (2006) Molecular Dynamics of the Shewanella oneidensis Response to Chromate Stress. Molecular and Cellular Proteomics. 5(6): 1054-1071.
- Chourey, K., Thompson, M. R., Morrell-Falvey, J., VerBerkmoes, N. C., Brown, S. D., Shah, M., Hettich, R. L., Zhou, J., Doktycz, M., and Thompson, D. K. (2006) Global Molecular and Morphological Effects of 24-h Chromium Exposure on Shewanella oneidensis MR-1. Applied and Environmental Microbiology. 72(9):6331-6344.
- Tabb, D. L., Thompson, M. R., Khalsa-Moyers, G., VerBerkmoes, N. C., McDonald, W. H. (2005) MS2Grouper: Group Assessment and Synthetic Replacement of Duplicate Proteomic Tandem Mass Spectra. Journal of the American Society for Mass Spectrometry. 16(8): 1250-1261.
- Narasimhan, C., Tabb, D.L., VerBerkmoes, N. C., Thompson, M. R., Hettich, R. L., Uberbacher, E. C. (2005) MASPIC: Intensity-Based Tandem Mass Spectrometry Scoring Scheme That Improves Peptide Identification at High Confidence. Analytical Chemistry. 77(23): 7581 - 7593.
- Clifton, S. W., Minx, P., Fauron, C. M., Gibson, M., Allen, J. O., Sun, H., Thompson, M., Barbazuk, W. B., Kanuganti, S., Tayloe, C., Meyer, L., Wilson, R. K., Newton, K. J. (2004) Sequence and comparative analysis of the maize NB mitochondrial genome. Plant Physiology. 136(3): 3486-503.