Valenzuela J.,Center for Biofilm Engineering |
Carlson R.P.,Center for Biofilm Engineering |
Carlson R.P.,Montana State University |
Gerlach R.,Center for Biofilm Engineering |
And 5 more authors.
Biotechnology for Biofuels | Year: 2012
Background: Phaeodactylum tricornutum is a unicellular diatom in the class Bacillariophyceae. The full genome has been sequenced (<30 Mb), and approximately 20 to 30% triacylglyceride (TAG) accumulation on a dry cell basis has been reported under different growth conditions. To elucidate P. tricornutum gene expression profiles during nutrient-deprivation and lipid-accumulation, cell cultures were grown with a nitrate to phosphate ratio of 20:1 (N:P) and whole-genome transcripts were monitored over time via RNA-sequence determination. Results: The specific Nile Red (NR) fluorescence (NR fluorescence per cell) increased over time; however, the increase in NR fluorescence was initiated before external nitrate was completely exhausted. Exogenous phosphate was depleted before nitrate, and these results indicated that the depletion of exogenous phosphate might be an early trigger for lipid accumulation that is magnified upon nitrate depletion. As expected, many of the genes associated with nitrate and phosphate utilization were up-expressed. The diatom-specific cyclins cyc7 and cyc10 were down-expressed during the nutrient-deplete state, and cyclin B1 was up-expressed during lipid-accumulation after growth cessation. While many of the genes associated with the C3 pathway for photosynthetic carbon reduction were not significantly altered, genes involved in a putative C4 pathway for photosynthetic carbon assimilation were up-expressed as the cells depleted nitrate, phosphate, and exogenous dissolved inorganic carbon (DIC) levels. P. tricornutum has multiple, putative carbonic anhydrases, but only two were significantly up-expressed (2-fold and 4-fold) at the last time point when exogenous DIC levels had increased after the cessation of growth. Alternative pathways that could utilize HCO 3 - were also suggested by the gene expression profiles (e.g., putative propionyl-CoA and methylmalonyl-CoA decarboxylases). Conclusions: The results indicate that P. tricornutum continued carbon dioxide reduction when population growth was arrested and different carbon-concentrating mechanisms were used dependent upon exogenous DIC levels. Based upon overall low gene expression levels for fatty acid synthesis, the results also suggest that the build-up of precursors to the acetyl-CoA carboxylases may play a more significant role in TAG synthesis rather than the actual enzyme levels of acetyl-CoA carboxylases per se. The presented insights into the types and timing of cellular responses to inorganic carbon will help maximize photoautotrophic carbon flow to lipid accumulation. © 2012 Valenzuela et al.; licensee BioMed Central Ltd.
Cook K.,Montana State University |
Cook K.,Center for Biofilm Engineering |
Adam S.,Montana State University |
Adam S.,Center for Biofilm Engineering |
And 6 more authors.
ASEE Annual Conference and Exposition, Conference Proceedings | Year: 2010
Mechanical Engineering Technology (MET) students have enhanced their educational experiences through industrial-based internships and undergraduate research activities within the university for many years. These experiences are especially important for MET students, as they generally respond better to the applications oriented learning pedagogy inherent in internship and research activities. While these activities vary in complexity and span the entire range of the mechanical engineering spectrum, they are almost always considered a "good learning experience". They learn by doing, thus it is important for them to be submersed in an environment where they can effectively learn the vocabulary and become intimately familiar with the needs and restraints for that environment. What is not well understood is how much these learning experiences contribute to skills development of the individuals involved. In addition, it is challenging to assess how effectively these students are supporting the goals of the researchers or technical faculty involved with the internship. This paper provides a description of a unique educational opportunity provided to Montana State University (MSU) MET students in collaboration with the Center for Biofilm Engineering, an NSF Engineering Research Center at MSU. This highly interdisciplinary collaboration provided an opportunity to improve, evaluate and assess the effectiveness of MET undergraduate internships and research support activities. Specifically, the focus was to share the skills and abilities of each discipline (Mechanical Engineering, Microbiology, Biofilm Engineering) and bridge the gap between research personnel in the design, prototyping, testing, manufacturing, and marketing of novel laboratory biofilm-related research equipment. The paper will present the project development history, goals of the project, and improvement activities implemented as a result of the project. In addition, details of the assessment plan, including MET program assessment goals, as well as the research and technical faculty assessment goals will be presented. Finally, the format for this type of internship or undergraduate research activity will be formalized and plans for expanding this activity campus wide will be presented. © American Society for Engineering Education, 2010.