I'm a third-year Ph.D. student in the MIT/WHOI Joint Program. I am in the Department of Earth, Atmospheric and Planetary Sciences at MIT, and the Marine Chemistry & Geochemistry Department at WHOI.
My primary advisor is Shuhei Ono at MIT.
My undergraduate degree is from the Department of Chemistry and Biochemistry at the California State University, Los Angeles. At Cal State L.A., I worked on the stable isotope geochemistry of chromium under the tutelage of Andre Ellis. I also studied cancer biology in the lab of Oliver Dorigo at UCLA.
I am broadly interested in organic metamorphism, Earth history, and biogeochemical cycling. You can read about about my current and past projects below.
My abbreviated CV is here.
I've been working with Shuhei Ono and Tanja Bosak at MIT on my qualifying exam project, characterizing sulfur isotope fractionation by sulfate-reducing bacteria during growth on different organic substrates. These bacteria turn sulfate into sulfide, and in the process consume & oxidize organic carbon. This process is important globally—as much as half of the organic matter oxidized in shelf environments may be due to sulfate reduction.
Lighter isotopes of sulfur in sulfate are preferentially reduced (i.e., the isotopes "fractionate" between reactant and product pools). but various environmental and organism-specific factors influence the magnitude of the fractionation. Understanding the controls on sulfur isotope fractionation is important because variations sulfur isotope abundances are widely used to infer past changes in global carbon and sulfur cycling. I am testing the hypothesis that these microbes will fractionate differently (and consistently so) depending on the quality of organic matter available to them. Photos of some of our experimental methods are below.
I had the fantastic opportunity to participate in the 2013 International GeoBiology Summer Course. A big thanks to the folks at the Agouron Institute and other funding agencies for supporting this program. You can find a sweet video of the course embedded below.
With faculty and other students on the course, I spent a few weeks studying stromatolites. Stromatolites are common sedimentary rock structures which contain layers that grow outward from a single point. (You can see a photo of one we collected below.)
Because stromatolites grow by accreting material from their environment, their layers could record information about changes in the environment in which the stromatolite was growing. We sampled the layers of a lacustrine stromatolite from the Eocene Green River Formation in Wyoming for isotopic and elemental analyses, and interpreted variations between layers as recording large-scale changes in the hydrology of Lake Gosiute ~50 million years ago.
Stromatolites can be formed by biological action, but abiological processes can create stromatolites as well—and it's sometimes very difficult to say which mechanism(s) created the forms in a particular rock. We collected microbial mats from an intertidal flat on Catalina Island, California, and performed experiments to better characterize the abilities of microbial mats to accrete debris. Experiments like these may help clarify the origins of particular stromatolite forms in the rock record.
With Mak Saito at WHOI, I worked on laboratory cultures of marine heterotrophs to better understand how rates of organic matter degradation in the oceanic water column might be affected by the availability of micronutrients. Certain elements (zinc, for example) are essential cofactors for enzymes used to break down organic matter. These metals can be extremely scarce in certain regions of the ocean, such that heterotrophic activity could be limited by the concentration of the required metal. Understanding these links between trace elements and the oceanic carbon budget will better illuminate how marine regimes may be affected by anthropogenic perturbations to global element fluxes.
Towards that end, I participated in a month-long research cruise in the equatorial Pacific aboard the R/V Kilo Moana (Lamborg and Saito, chief scientists). This expedition, dubbed "Metzyme", collected a full-depth dissolved and particulate trace metal profile from Hawaii to Samoa. We also collected samples for metaproteomic analyses to determine whether the abundances of certain proteins are affected by micronutrient availability. Some photos from Metzyme are below.
In 2010, I began working with Andre Ellis to help develop chromium stable isotopes as tracers of chromium contamination in groundwater. In a study presented at AGU, we measured isotopic fractionation during the oxidation of chromium(III) to (VI) by environmentally-prevalent manganese oxides. Tracking chromium's stable isotopes is a promising new approach to monitoring remediation of chromium(VI) spills, as the isotopic signatures are not significantly affected by transport or sorption. Hexavalent chromium is more mobile and toxic than chromium(III), and as such, we would like to know how redox behavior of chromium is recorded by changes in its stable isotope composition. Our experimental results suggested that chromium oxidation imparts only small isotopic fractionations. On the other hand, previous results suggest that reduction of Cr(VI) to (III) imparts much larger fractionations. Thus, chromium isotope signatures appear to primarily reflect reductive processes. As chromium reduction is the primary method of in situ remediation, this result is promising for the application of chromium isotopes for monitoring remediation of contaminated sites.
For three summers, I studied ovarian cancer cells with Oliver Dorigo and postdoctoral scholar Chintda Santiskulvong at UCLA. For the last of the three summers (2010), I was a summer intern through the Amgen Scholars Program. In the Dorigo lab, I worked to characterize the regulation of cellular resistance to cisplatin, a chemotherapy agent. By understanding the development of drug resistance in tumors, we can overcome a major obstacle to the long-term effectiveness of chemotherapy. I performed transcriptomic and protein expression profiling on various strains of tumor cells. The result was a list of differentially-expressed signaling biomolecules. I then characterized one of these molecules, the insulin-like growth factor 1 receptor, for its potential role in cisplatin resistance. Examples of the data generated during the course of this project are shown in the figures below.
Name underlined on presentations for which I was presenting author.
We traveled to Fayetteville Green Lake, New York in summer of 2013 to collect water column and sediment samples. Green Lake is a deep (~50 m), permanently-stratified lake with anoxic, sulfidic bottom waters. We are interested in the biogeochemical cycling of carbon and sulfur in this lake, as a potential model system for sulfidic oceans through time.