College of Letters & Science
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The College of Letters and Science, the largest center for learning, teaching and research at Montana State University, offers students an excellent liberal arts and sciences education in nearly 50 majors, 25 minors and over 25 graduate degrees within the four areas of the humanities, natural sciences, mathematics and social sciences.
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Item Real-Time Digitization of Metabolomics Patterns from a Living System Using Mass Spectrometry(2014-10) Heinemann, Joshua; Noon, Brigit; Mohigmi, Mohammad J.; Mazurie, Aurélien J.; Dickensheets, David L.; Bothner, BrianThe real-time quantification of changes in intracellular metabolic activities has the potential to vastly improve upon traditional transcriptomics and metabolomics assays for the prediction of current and future cellular phenotypes. This is in part because intracellular processes reveal themselves as specific temporal patterns of variation in metabolite abundance that can be detected with existing signal processing algorithms. Although metabolite abundance levels can be quantified by mass spectrometry (MS), large-scale real-time monitoring of metabolite abundance has yet to be realized because of technological limitations for fast extraction of metabolites from cells and biological fluids. To address this issue, we have designed a microfluidic-based inline small molecule extraction system, which allows for continuous metabolomic analysis of living systems using MS. The system requires minimal supervision, and has been successful at real-time monitoring of bacteria and blood. Feature-based pattern analysis of Escherichia coli growth and stress revealed cyclic patterns and forecastable metabolic trajectories. Using these trajectories, future phenotypes could be inferred as they exhibit predictable transitions in both growth and stress related changes. Herein, we describe an interface for tracking metabolic changes directly from blood or cell suspension in real-time.Item Group A Streptococcus Secreted Esterase Hydrolyzes Platelet-Activating Factor to Impede Neutrophil Recruitment and Facilitate InnateImmune Evasion(2012-04) Liu, Mengyao; Zhu, Hui; Li, Jinquan; Garcia, C. C.; Feng, Wenchao; Kirpotina, Liliya N.; Hilmer, Jonathan K.; Tavares, L. P.; Layton, A. W.; Quinn, Mark T.; Bothner, Brian; Teixeira, M. M.; Lei, BenfangThe innate immune system is the first line of host defense against invading organisms. Thus, pathogens have developed virulence mechanisms to evade the innate immune system. Here, we report a novel means for inhibition of neutrophil recruitment by Group A Streptococcus (GAS). Deletion of the secreted esterase gene (designated sse) in M1T1 GAS strains with (MGAS5005) and without (MGAS2221) a null covS mutation enhances neutrophil ingress to infection sites in the skin of mice. In trans expression of SsE in MGAS2221 reduces neutrophil recruitment and enhances skin invasion. The sse deletion mutant of MGAS5005 (ΔsseMGAS5005) is more efficiently cleared from skin than the parent strain. SsE hydrolyzes the sn-2 ester bond of platelet-activating factor (PAF), converting biologically active PAF into inactive lyso-PAF. KM and kcat of SsE for hydrolysis of 2-thio-PAF were similar to those of the human plasma PAF acetylhydrolase. Treatment of PAF with SsE abolishes the capacity of PAF to induce activation and chemotaxis of human neutrophils. More importantly, PAF receptor-deficient mice significantly reduce neutrophil infiltration to the site of ΔsseMGAS5005 infection. These findings identify the first secreted PAF acetylhydrolase of bacterial pathogens and support a novel GAS evasion mechanism that reduces phagocyte recruitment to sites of infection by inactivating PAF, providing a new paradigm for bacterial evasion of neutrophil responses.