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Chemical and Biomolecular Engineering

Mary L. Kraft, Associate Professor in Chemical and Biomolecular Engineering, has been named a Robert W. Schaefer Faculty Scholar, a position established by the late Robert Schaefer, a chemical engineering alumnus.

Associate Professor Mary L. Kraft
Associate Professor Mary L. Kraft

Kraft investigates bioimaging, drug delivery, single cell analysis, and multivariate statistics. Her research group is developing new approaches in which compositional signatures acquired from individual cells are used to understand and predict biological function. They use these techniques for applied research, such as detecting stem cell differentiation for tissue engineering, and for basic research on the roles of plasma membrane organization in influenza virus replication and other important biological processes.

“Besides exciting science and method development, Kraft is a suburb teacher and advisor,” said Jonathan Sweedler, director of the School of Chemical Sciences and James R. Eiszner Family Chair of the Department of Chemistry. She was a recipient of the Engineering Council Award for Excellence in Advising and received a 2015 SCS faculty teaching award. In addition, chemical engineering students and the Engineering Council’s Advisors List Selection Committee chose Kraft as one of the top 10 percent of engineering advisors.

Kraft joined the Department of Chemical and Biomolecular Engineering faculty in 2007. She graduated with a B.S. in Biochemistry from the University of Illinois at Chicago in 1998 and earned her Ph.D. in Chemistry from the University of Illinois at Urbana-Champaign in 2003. She was a Postdoctoral Fellow at Stanford University. The faculty scholar appointment is effective August 16, 2016.

Robert W. Schaefer graduated summa cum laude from Illinois in 1956. After earning his BS in Chemical Engineering, Schaefer served in the U.S. Navy. On release from the Navy, he joined Shell Chemical Company in Houston, Texas, followed by the Monsanto Company in St. Louis, where he spent 28 years. While with Monsanto, he worked in Food and Fine Chemicals, Rubber Chemicals, and on Roundup. He was part of the team which introduced L-Dopa, the breakthrough Parkinson’s Disease drug, to the marketplace.

 

Congratulations to faculty and graduate students recognized by the University of Illinois School of Chemical Sciences for their teaching excellence in the 2014-2015 academic year. Those in Chemical and Biomolecular Engineering who received awards include Associate Professor Mary Kraft, Assistant Professor David Flaherty, and Lecturer Troy Vogel, plus graduate students Qilong Huang and Vahid Mirshafiee.

“The award recognizes the entire scope of our educational efforts, from course development to in-class instruction. Excellence in teaching is not only intellectually satisfying, but our instructional efforts immeasurably strengthen our research mission,” said Jonathan Sweedler, director of the School of Chemical Sciences.

Others honored with 2014-2015 SCS Teaching Awards include Martin Gruebele, the James R. Eiszner Endowed Chair in Chemistry; Prashant Jain, Assistant Professor of Chemistry; plus chemistry graduate students Ambika Bhagi, Elizabeth Parkinson, and Cody Tripp.

 

Professor Mary Kraft was awarded the 2014 Walter A. Shaw Young Investigator Award in Lipid Research
Mary Kraft

Professor Mary Kraft in the Department of Chemical and Biomolecular Engineering is the recipient of the 2014 Walter A. Shaw Young Investigator Award in Lipid Research from the American Society for Biochemistry and Molecular Biology (ASBMB).

The Walter A. Shaw Young Investigator Award in Lipid Research, established by ASBMB’s Lipid Research Division, recognizes outstanding research contributions in the area of lipids by young investigators.

Kraft said she is honored to receive the award for her research in which she and her researchers have “pioneered the application of a new high-resolution imaging mass spectrometry technique to identify how cholesterol and sphingolipids are organized in cell membranes, which addresses a key dispute in cell biology.”

She says the award is a great honor because it “demonstrates that the biochemistry and cell biology community recognizes the importance of my research.”

“The award helps to disseminate my findings to scientists outside of Chemical and Biomolecular Engineering, namely to biochemists and molecular and cellular biologists,” Kraft said.

In her research, Kraft has developed and validated methods to quantitatively image the lipid composition of small regions of membranes in cells using high resolution mass spectrometry imaging combined with metabolic isotope labeling. She has made important discoveries related to the sphingolipid and cholesterol organization in cell membranes that have major implications for our understanding of plasma membrane organization.

Kraft received her undergraduate degree from the University of Illinois in Chicago, her Ph.D. in Chemistry from the University of Illinois, followed by a postdoctoral fellowship at Stanford University. She joined the faculty at the University of Illinois in 2007.

Assistant Professor Mary Kraft
Dr. Mary Kraft

Assistant Professor Mary Kraft and researchers reported that lipids may not be arranged the way researchers thought, coming to that conclusion by using mass spectrometry to visualize synthetic and real lipid membranes. Those findings were presented at the Division of Colloid and Surface Chemistry at the American Chemical Society national meeting in New Orleans in April. Read more about this research in an article in Chemical and Engineering News.  

The results highlighted in the Chemical and Engineering News article are from a recently published paper in The Journal of Biological Chemistry.

 

Sight would dramatically alter a blind man’s understanding of an elephant, according to the old story. Now, a look directly at a cell surface is changing our understanding of cell membrane organization.

Using a completely new approach to imaging cell membranes, a study by researchers from the University of Illinois, Lawrence Livermore National Laboratory and the National Institutes of Health revealed some surprising relationships among molecules within cell membranes.

ChBE professor Mary Kraft led the research team Photo by L. Brian Stauffer
ChBE professor Mary Kraft led the research team Photo by L. Brian Stauffer

Led by Mary Kraft, a U. of I. professor of chemical and biomolecular engineering, the team published its findings in the Proceedings of the National Academy of Sciences (PNAS).

Cells are enveloped in semi-permeable membranes that act as a barrier between the inside and outside of the cell. The membrane is mainly composed of a class of molecules called lipids, studded with proteins that help regulate how the cell responds to its environment.

“Lipids have multiple functions serving as both membrane structure and signaling molecules, so they regulate other functions inside the cell,” Kraft said. “Therefore, understanding how they’re organized is important. You need to know where they are to figure out how they’re doing these regulatory functions.”

One widely held belief among cell biologists is that lipids in the membrane assemble into patches, called domains, that differ in composition. However, research into how lipids are organized in the membrane, and how that organization affects cell function, has been hampered by the lack of direct observation. Although the cell membrane is heavily studied, the imaging techniques used infer the locations of certain molecules based on assumed associations with other molecules.

In the new study, Kraft’s team used an advanced, molecule-specific imaging method that allowed the researchers to look at the membrane itself and map a particular type of lipid on mouse cell membranes. The researchers fed lipids labeled with rare stable isotopes to the cells and then imaged the distribution of the isotopes with high-resolution imaging mass spectrometry.

Researchers found that a class of molecules called sphingolipds congregate in large patches in the cell membrane. Red and yellow colors indicate local elevations in the sphingolipid abundance. Photo by Kevin Carpenter
Researchers found that a class of molecules called sphingolipds congregate in large patches in the cell membrane. Red and yellow colors indicate local elevations in the sphingolipid abundance. Photo by Kevin Carpenter

Called sphingolipids (SFING-go-lih-pids), these molecules are thought to associate with cholesterol to form small domains about 200 nanometers across. The direct imaging method revealed that sphingolipids do indeed form domains, but not in the way the researchers expected.

The domains were much bigger than suggested by prior experiments. The 200-nanometer domains clustered together to form much larger, micrometer-sized patches of sphingolipids in the membrane.

“We were amazed when we saw the first images of the patches of sphingolipids across the cell surface,” said Peter Weber, who directed the team at Lawrence Livermore National Laboratory. “We weren’t sure if our imaging mass spectrometry method would be sensitive enough to detect the labeled lipids, let alone what we would see.”

Furthermore, when the researchers looked at cells that were low on cholesterol – thought to play a key role in lipid aggregation – they were surprised to find that the lipids still formed domains. On the other hand, disruption to the cell’s structural scaffold seemed to dissolve the lipid clusters.

“We found that the presence of domains was somewhat affected by cholesterol but was more affected by the cytoskeleton – the protein network underneath the membrane,” Kraft said. “The central issue is that the data are suggesting that the mechanism that’s responsible for these domains is much more complicated than initially expected.”

In addition, the new study found that sphingolipids domains were incompletely associated with a marker protein that researchers have long assumed dwelled where sphingolipids congregated. This means that data collected with imaging techniques that target this protein are not as accurate in representing sphingolipid distribution as previously thought.

“Our data are showing that if you want to know where sphingolipids are, look at the lipid, don’t infer where it is based on other molecules, and now there’s a way to directly image them,” said Kraft, who also is affiliated with the department of chemistry at the U. of I.

Next, the researchers plan to use the direct-imaging method in conjunction with other more conventional methods, such as fluorescence, to further determine the organization of different kinds of molecules in the membrane, their interactions and how they affect the cell’s function. They plan to begin by targeting cholesterol.

“Cholesterol abundance is important,” Kraft said. “You change that, you tremendously change cell function. How is it organized? Is it also in domains? That’s related to the question, what’s the mechanism responsible for these structures and what are they doing?”

The National Institutes of Health, Lawrence Livermore National Laboratory, the National Science Foundation and the Burroughs Wellcome Fund supported this work. Co-author Joshua Zimmerberg directed research at the Eunice Kennedy Shriver National Institute of Child Health and Human Development, part of the National Institutes of Health.

Editor’s Note: The paper, “Direct chemical evidence for sphingolipid domains in the plasma membranes of fibroblasts,” is available from PNAS.

Cell Photo: Kevin Carpenter
Faculty Photo: L. Brian Stauffer

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