Science Close Up: High School Students Use Cutting Edge Microscopy at the PGSS-Mellon College of Science - Carnegie Mellon University

Monday, August 15, 2005

Science Close Up: High School Students Use Cutting Edge Microscopy at the PGSS

Many high school students have gazed through the eyepiece of a standard light microscope, twisting and turning dials to magnify a specimen. But few, if any, get to use an atomic force microscope (AFM), which can produce exquisitely detailed images at the nanoscale. Ten high school juniors spent five weeks this summer on Carnegie Mellon’s campus using AFM to study the structure of yeast as part of the Pennsylvania Governor's School for Sciences (PGSS).  Their project, “Determining the effects of oxidants and anti-oxidants on the structure of medicinal and Brewer's yeast,” is part of the intensive PGSS program, in which students experience educational and research activities not normally available to them through their high schools.

“This team project combines physics and biology and offers the students the opportunity to experience the ups and downs of scientific research. Even after only 5 weeks, the students were able to generate impressive images of live yeast and the formation of pores in the cell wall due to oxidants,” said Christopher Borysenko, Director of Carnegie Mellon’s Interdisciplinary Laboratory and a PGSS instructor.

Various types of yeasts have been used for decades in over-the-counter medications for the treatment of burns, wounds and intestinal disorders, and many experiments are underway to study yeast’s additional medicinal benefits. The PGSS students, whose program ran from June 27 to July 29, explored how the oxidant diamide and anti-oxidants (Vitamin C, for example) affect the structure and viability of yeast. Results of studies like these could be helpful in guiding how medicinal yeast is formulated by showing which agents actually injure yeast and which are protective, thus extending its therapeutic use.

Using the AFM, provided by Randy Feenstra, professor of physics, with support from the Department of Physics, the students were able to see, with great detail, how the structure of yeast cells is altered after exposure to oxidants and anti-oxidants. In AFM, a tiny lever ending with an ultra-sharp tip is scanned across a surface from side-to-side and top-to-bottom, much as a cursor moves across a computer screen. A laser beam reflected off the lever’s end monitors its vertical motion. Perturbation of the lever motion by nanoscale features of the yeast cells’ surface topography is used to reconstruct a detailed three-dimensional map of the surface.

“The project demonstrates an interesting interdisciplinary approach to defining a biological system,” said Borysenko.

Since its 1982 inception, nearly 2,000 talented Pennsylvania high school students have participated in the PGSS, which is now under the stewardship of Director Barry Luokkala, a teaching professor in the department of physics. The students participate in core courses covering the latest advances in biology, chemistry, physics, mathematics and computer science, as well as elective courses on such topics as astrophysics, materials science and modern protein-based drugs. In addition to their rigorous class schedule, students spend four afternoons each week in the lab either participating in a formal lab class or working on their team projects. For more information on the PGSS, please visit:

By: Amy Pavlak