Contact info can be found here.

Renée in California, USA (Sept. 2016)

Renée using an ICP-MS at USC to measure trace metals in sediments from Peru (April 2014).

Renée collecting sediment samples for mercury analysis while working at the U.S. Geological Survey (July 2015).

About Renée

I'm a PhD Student in Geochemistry at Caltech who combines techniques from stable isotope geochemistry and biochemistry. My current projects are about: 1) Chronic bacterial infections, and 2) Evolution of Carbon-Fixing Metabolism. 

My current main projects ask the questions:

1. How do pathogens manage to survive and persist in chronic infections? Most encounters with pathogenic bacteria can be resolved by the host's immune system, but in a minority of cases, opportunistic bacterial pathogens manage to adapt, survive, and persist in their hosts to establish chronic (sometimes life-long) infections. Use of denitrification (a type of anaerobic respiration) by bacteria has been correlated with chronic infections in lab studies, but this has not yet been verified in vivo (in living humans). We are adapting a natural-abundance, stable-isotope tracer originally developed for studying soil denitrification to monitoring pathogenic denitrification in humans. Our model system is the chronic respiratory infection found in Cystic Fibrosis (CF) patients, and our model pathogen is the bacterium Pseudomonas aeruginosa​. (Advised by Profs. Dianne Newman and John Eiler at Caltech, in collaboration with others from the USC Medical School.)

2. How has the evolution of metabolism has affected Carbon Isotope Records through time? Concentrations of stable carbon isotopes, C-13 and C-12, preserved in the rock record are the most far-reaching tracer Earth Scientists have for understanding how life evolved through geologic time. Changes in the ratio of C-13 vs. C-12 have recorded ecological changes like mass extinctions, and environmental changes, like warming and cooling periods. However, our interpretation of some of these proxies are based on lab experiments done on modern organisms with modern metabolisms, even though metabolism has clearly evolved through time, with potential consequences for C isotope proxies. We have been addressing this question by studying the C isotope measurements of a modern cyanobacterial strain with a reconstructed ancestral (>>1 billion years) Rubisco enzyme. Rubisco is the enzyme that "fixes" CO2 to organic C in the Calvin Cycle, the most widely used C-fixing metabolism in nature. (Advised by Prof. Woody Fischer at Caltech, in collaboration with others from UC Berkeley and UC Davis.)