News

St. Olaf College Professor of Biology Eric Cole, a group of student researchers, and a microscopic organism are making big news this spring.

Cole’s cell biology research was recently published as the cover article of a scientific journal, and later this month two of his students will present findings related to that article at an international meeting in Boston.

Journal cover story
Cole’s article, “Membrane Dynamics at the Nuclear Exchange Junction during Early Mating in the Ciliate Tetrahymena thermophila,” was featured on the February cover of Eukaryotic Cell, a scientific journal from the American Society for Microbiology.

Its publication marks the end of a six-year scientific quest that involved eight undergraduate students, two college campuses, and one single-celled study organism — the ciliated protist Tetrahymena thermophila.

Tetrahymena thermophila (T. thermophila) is a single-celled organism that acts as a bacterial grazer in freshwater lakes and ponds. It is considered a model organism for molecular and cellular biology due to its rapid growth and possession of key eukaryotic processes.

The research process
In the fall of 2008, Cole spent a semester of released time at the University of Colorado, Boulder. In the university’s electron microscope suite, Cole learned how to perform three-dimensional electron tomography, a process that allows scientists to determine a cell’s three-dimensional architecture.

In 2012 Cole returned to U.C. Boulder, this time to lead eight St. Olaf students in an electron microscopy course.

“At the time, U.C. Boulder was one of only three such microscopy facilities in the country, and nowhere were undergraduates privileged with time on such an instrument,” says Cole. “The site director was so impressed with our students’ passion and commitment that he invited us back again.”

Six students from Cole’s 2012 Interim course continued working with him throughout that spring. They developed 3-D computer models of the cell structures they had captured in January, and two students — Anna Ballard ’13 and Tyler Aronstein ’12 — animated these models. Ballard and Aronstein are co-authors on Cole’s 2015 paper.

The team’s work also caught the attention of a Scientific American weblog, which published a story about the students’ activities.

Results and future questions
“I think there were three notable findings from our study,” says Cole. “First, we captured the moment when two cells initially fuse with one another during fertilization. Second, we identified a new set of membrane structures that anchor cell nuclei to the cell-cell junction and to one another through pores that form in the mating junction. Finally, we discovered tiny membrane-bound packages that are secreted by cells into the mating junction.”

This last discovery led to a new research question in Cole’s lab: are cells communicating with each other through these membrane-bound packages?

Student researchers Sasha Dmytrenko ‘16 and Adrian Ripeckyj ‘17 spent last summer purifying these “packages” from mating T. thermophila cells. Once the packages were purified, samples were sent to the University of Minnesota, where a technique called mass spectrometry was used to identify every type of protein present in the vesicles. They identified a total of 370 proteins, three of which were involved in a process called “RNA interference.”

“This is a new and exciting finding, that our vesicles might be carrying small RNA molecules from one cell to the other, possibly acting as ‘signal’ molecules during mating,” says Cole. “This summer we hope to identify which, if any, RNA molecules are present in our microvesicles.”

Dmytrenko and Ripeckyj will report on their successful efforts to purify these microvesicles at an international meeting in Boston over spring break.