Thelen is a native of Nebraska who, after earning his doctorate at MU and completing postdoctoral training at Michigan State University, decided he was happy to stay in the Midwest. "I guess I made it pretty easy on them when we negotiated my contract," he says. With his youthful appearance and understated manner, it can be hard to distinguish him from the earnest group of graduate students and postdoctoral biochemists who work with him.
At a dry-erase board mounted on the wall of a light-filled room in the MU Christoper S. Bond Life Sciences Center, Thelen and a group of his young colleagues patiently offer a tutorial on the basics of genomic science. "We do mostly proteomics research," begins Thelen, "which is more or less a fancy word for the study of proteins."
Proteomics, he continues, is related to the better-known field of genomics. A genome is typically defined as the "totality of DNA sequences in an organism." Because DNA determines the exact sequence by which amino acids are formed into proteins, the DNA of a particular organism is said to be "fully annotated" when all of its sequence information is "mapped" to discrete genes for researchers to follow. Less well known is the regulation of the RNA, or ribonucleic acid, which actually "transcribes" DNA's genetic code for use in amino acid assembly. Study of the transcription process has created an important sub-discipline called transcriptomics, a field where researchers seek to map an organism's "transcriptome," or the full set of RNA transcripts produced by its genome.
Since DNA contains a huge number of possible genes -- genes that will ultimately produce different types of proteins -- Thelen and other proteomics researchers depend on genomics and transcriptomics to help them identify promising areas for exploration. But make no mistake, Thelen says, the proteins are the star attraction.
"My particular bias is this," he says. "You can study DNA and RNA and think you have a handle on what's responsible for phenotype. But, in fact, there are changes from DNA to RNA to protein that don't always correlate with one another. Ultimately, proteins are responsible for any given trait and therefore understanding their regulation and function is key."
Early in his career, Thelen joined the relatively small cohort of international scientists who recognized that protein exploration was the next logical step in genetics research. And as the tools necessary for investigating this tiny realm became more sophisticated, so did the buzz surrounding the field.
With the buzz has come money. Thelen's 2003 proposal to the National Science Foundation, for example, yielded a $1.2 million, five-year grant -- some $100,000 more than he requested. Thelen used the money, from the NSF's Plant Genome Research Program, to purchase equipment, most notably a mass spectrometer to measure molecular weights of peptides, and to assemble a cosmopolitan team of young researchers.
The immediate goal of the NSF project is to discover the location and interactions of cellular proteins from soybeans and other oil seeds at key stages of their development. This information, Thelen says, will allow his team to chart the metabolic pathways regulating growth -- including growth at the crucial oil-filling stage.
"There really hasn't been much of a push to understand the expression trends that are occurring during oil-seed development," Thelen says. "There are radical changes going on during this brief four-to-six week period, when sugars from leaves are assimilated into mostly oil and protein within the seed. What we need to find out are the dynamics of the protein networks during this relatively short time window."
Toward this end, Thelen is relying on scientists such as Martin Hajduch, 34, a postdoctoral researcher from Slovakia. Hajduch is developing "expression profiles," a means of identifying and classifying individual proteins by their uniqueness and function. In a recently published study, for example, Hajduch profiled 679 proteins found in a popular variety of soybean plant. From these he was able to develop digital "reference maps" that allowed researchers to learn whether each of these proteins was expressing or stable at different stages of the seed-fill.
Hajduch says he and his colleagues are currently working to complete similar maps for other important oil-seed crops. Plant geneticists will use these to maps to select, and then "model," those proteins responsible for the seed-fillings traits they deemed most desirable. "If we can make theoretical models, then we can start to test these models and, eventually, engineer the plants to produce seeds with improved quality," he says.
Published by the Office of Research.
©2006 Curators of the University of Missouri. Click here to contact the editor.