One of the coolest machines in an MBL course this summer—and the courses are famous for having absolutely the best laboratory instrumentation you can get—is a high-pressure freezer, on loan from Leica, in the Physiology course. With an impressive burst of steam, it instantly turns a tissue sample into a flash-frozen slab. Then, the sample can be sliced and observed in an electron microscope, its biological activity freeze-framed at that instant of time.
But what’s really cool is this machine is an offshoot of the “freeze slammer” that MBL Neurobiology course faculty Tom Reese and John Heuser built in the late 1970s. “We pioneered a different kind of freezing, called slam freezing, with the idea of stopping tissue action. We used a copper plate cooled with liquid helium, and we slammed a piece of tissue against it,” says Reese, a researcher at the National Institutes of Health who is now in his 35th year of teaching in the MBL Neurobiology course. Reese and Heuser were able to release synaptic vesicles from frog neurons and capture the event using the slam freezer. “No one had ever observed structure on a millisecond time scale before (this),” Reese says.
“It was a classic experiment,” says Erik Jorgensen of HHMI/University of Utah, a neurobiologist who is “frequently found at the MBL in the summer trying to pull off experiments that cannot be done anywhere else,” he says. Jorgensen has modified the Leica freezer to perform like the freeze slammer, so he can observe instantaneous synaptic events, as Reese and Heuser did. Jorgensen remembers seeing the old Reese-Heuser freeze slammer in the basement of Loeb Laboratory. “These old machines, you had to be an engineer to run them,” Reese remembers. “The new ones are so easy to use, you find it sitting there in the Physiology course for the students to try out!”
Visiting investigator Erik Jorgensen demonstrates the high-pressure freezer in the Physiology course, which takes a cue from the freeze slammer invented by Neurobiology faculty Tom Reese and John Heuser in the late 1970s. Photo by Tom Kleindinst