Ph.D., Biological Oceanography. University of Washington (2013).
M.Sc., Oceanography. University of Washington (2009).
B.A. summa cum laude, Biological Sciences. Rutgers University (2005).
My research is motivated by the overarching question, How does nitrogen availability affect diatom physiology and in turn, how does diatom physiology impact the marine environment through the drawdown of nitrogen?
During my graduate school tenure, I have worked in the laboratory on individual diatom species, as well as embarked on several research cruises off of central California, Oregon, Washington and Vancouver Island to interrogate diatom nitrogen metabolism in diverse nitrogen regimes. My goal has been to identify and quantify transcript abundances for molecular markers of diatom N metabolism, including responses to different nitrogen sources and responses to different degrees of nitrogen availability. Ultimately, these molecular markers will be used as part of larger metatranscriptomic datasets to monitor changes in diatom N uptake and N assimilation in the field.
Project 1: The role of the urea cycle in the model marine diatom Thalassiosira pseudonana
This work improves our understanding of diatom intracellular processes by incorporating the urea cycle into the bigger picture of N metabolism in a model diatom and by examining the effect of nitrogen sources on these metabolic pathways.
(Shown left: Simplified schematic of diatom nitrogen metabolism. Protist 2012)
Project 2: Comparative diatom transcriptomics in response to the onset of nitrate starvation.
This project is motivated by the need to better understand diatom-shared traits of N metabolism during growth on low nitrogen, and to determine whether assumptions about a "uniform diatom response" to changes in nitrogen availability, are relevant given the diversity of the diatom group.
(Shown right: Cultures of Fragilariopsis cylindrus growing in the lab.)
Project 3: Using in situ markers of diatom metabolism coupled to metatranscriptomes to determine the nitrogen response of diatom field communities to changing nitrogen regimes.
Several research cruises steaming from the coast to the open ocean have allowed us to conduct onboard, deck incubations of the ambient phytoplankton community, as well as to collect large-scale filtrations for metatranscriptomic sequencing. This includes a recent collaboration between our lab group and GEOTRACES to couple 'omics sampling to trace ocean elements. Analyses of all of this work will provide a snapshot of diatom metabolism in the field, told from the cell's perspective.
(Shown left: Colleen wrestling with incubator tubing onboard the R/V Wecoma.)
Durkin, C.A., Bender, S.J., Chan, K.Y.K., Gaessner, K., Grunbaum, D., and Armbrust, E.V. (2013). Silicic acid supplied to coastal diatom communities influences cellular silicification and the potential export of carbon. Limnology and Oceanography. 58(5):1707-1726.
Bender, S.J., Parker, M.S. and Armbrust, E.V. (2012). The coupled effects of light and nitrogen source on the urea cycle and nitrogen metabolism over a diel cycle in the marine diatom Thalassiosira pseudonana. Protist. 163: 232-51.
Durkin, C.A., Marchetti, A., Bender, S.J., Truong, T., Morales, R., Mock, T. and Armbrust, E.V. (2012). Frustule-related gene transcription and the influence of diatom community composition on silica precipitation in an iron-limited environment. Limnology and Oceanography. 57(6): 1619-1633.
Bidle, K.D. and Bender, S.J. (2008). Iron starvation and culture age activate metacaspases and programmed cell death in the marine diatom, Thalassiosira pseudonana. Eukaryotic Cell. 223-46.