By Diana Kenney and Raleigh McElvery
Nobel Laureate Eric Betzig was back at the MBL in June with one of his latest innovations in microscopy.
Betzig and his group members, Wesley Legant and Ved Singh of HHMI’s Janelia Research Campus, installed the lattice light sheet microscope Betzig designed in the Physiology course, where it was available for all students, faculty and scientists on campus to use for two weeks. Legant and Singh were on hand to run the scope and offer technical advice.
This is the third invention that Betzig has brought to the MBL, where biologists are eager to test the scopes’ limits with various kinds of samples and experiments. The first microscope Betzig brought in 2007, called PALM (photoactivated localization microscopy), would later bring him the 2014 Nobel Prize in Chemistry.
But well before it excited the Nobel Committee, PALM inspired a rush of experiments in the Physiology course that led to several publications. “The form of PALM that has probably revealed the most biology came out of discussions with Jennifer Lippincott-Schwartz at Woods Hole in 2007,” Betzig said. Lippincott-Schwartz, of the National Institutes of Health, was then on the Physiology course faculty and now co-directs the course.
Yet PALM has its limitations, as do all super-resolution technologies, Betzig emphasized this year in his lectures to the Physiology students. “Technically speaking, PALM is extremely easy to do. You can build a home instrument without a lot of difficulty,” he said. “But the sample preparation is a [bear].”
In fact, “peeking under the metaphorical hood” of super-resolution technology reveals a myriad of interrelated challenges, the “tetrahedron of trade-offs,” Betzig told the students. “If you want higher spatial resolution, you need more pixels. But more pixels require more [measurements], and more measures take more time, which throws damaging light onto the specimen. You never get something for nothing,” he said. “Time and light are your enemies when it comes to live cell-imaging.”
Enter the lattice light sheet, which “rocks when it comes to live imaging,” according to Betzig. This microscope projects an ultra-thin sheet of light through the cell, illuminating just one plane of in-focus molecules at a time. It then sweeps this plane though the cell to build up a 3D image, and the process can be repeated to create a 4D movie over time. This design avoids flooding the entire cell with light, plus it can capture hundreds of 3D images at sub-second rates. “The data come off of the microscope so fast we can’t possibly process all the information at the rate at which we take it,” Betzig said.
Betzig is looking for ways to push the resolution of the lattice light sheet to its maximum. Recently, he and Legant used it in tandem with a super-resolution fluorescence technology called PAINT; among the 3D images they captured was a zebrafish sensory organ using a dataset consisting of over one billion localized molecules. “It was the biggest localization image I’d ever seen,” Betzig said. “But it gave new meaning to the phrase ‘watching paint dry,’ since it took a full 10 days at the microscope.”
Perhaps the creative biologists at the MBL will contribute to new and improved applications of Betzig’s technologies. It wouldn’t be the first time!
Photo at top: Volume renderings of the COS-7 cell as acquired with lattice light sheet-PAINT and lattice light sheet-PALM microscopy. Credit: Eric Betzig