Severin Stevenson introduces a subfield of biochemistry called quantitative proteomics. Proteomics deals with absolute quantification of proteins at any given time in a given sample compared with other protein samples. Because certain plants produce seeds that are valuable for their oil (e.g., cottonseed, peanuts, grape seed), scientists are interested in the plant’s physiology, specifically, its process of “seed-filling”—a period of development during which the seed produces oil. If scientists can understand the processes that contribute to the seed’s production of oil, they may be able to increase this production for economic gain.
Stevenson has been working with Jay J. Thelen’s Proteomics of Oilseeds Lab in the Bond Life Sciences Center. A typical experiment for Stevenson may involve adding fatty acids to cells growing in a sucrose suspension, taking a sample every hour over a period of days, extracting and treating protein from these samples and, finally, re-suspending the protein and then injecting samples into the mass spectrometer in order to quantify and analyze the chemical composition of the protein samples.
Stevenson and his team are working to elucidate the mechanism behind oil accumulation in seeds during seed filling. Plants sense the levels of various metabolites differently in different tissues, and seeds are unique in the ways in which they do this. Some seeds are well over 40% oil by dry weight, whereas leaves are under 5%. The differences in oil accumulation between these tissues provide evidence for the presence of a unique regulatory mechanism that they wish to understand and which may eventually benefit agricultural industries.