The 2,417th Meeting of the Society

December 6, 2019 at 8:00 PM

Powell Auditorium at the Cosmos Club

3-D Imaging: From Fly Brain Circuits to Cell Ultrastructure

A New Generation of Electron and Single Molecule Based Microscopes are Transforming Our View into Biology

Harald Hess

Group Leader
Howard Hughes Medical Institute - Janelia

Sponsored by PSW Science Member Tim Thomas

About the Lecture

Microscopes with 2D images have long provided the core of our understanding of the components of life, from tissues to cells to constituent molecules. In recent decades, 3D imaging is capturing new comprehensive details of the full 3D world of biology, enabled by recent strides in microscopy, ever larger scale data acquisition, data storage, neural network processing, and analysis.

Driven by the quest to understand neural circuits within even a modest sized brain, such as the laboratory fly has led to development 3-Dn focused ion beam scanning electron microscopy (FIBSEM). FIBSEM acquires 3D data by a cycle of 2D imaging and sample surface ablation of a few nanometer increments to expose the next surface to be imaged. Recent improvements with higher speeds, more cycles and year-long reliability now promise that volumes approaching a cubic millimeter can be resolved with a few nanometer detail. Complete reconstruction of the fly brain reveals an intricate weave of nerves forming vision, orientation, olfactory circuit and other modules.

A higher resolution mode of FIBSEM can be applied to image details of tissues and whole cells. Such a holistic 3D view offers a completeness that otherwise is missed in traditional electron microscopy where samples are limited by a diamond knife section thickness. All components from mitochondria, Golgi apparatus, centrosomes, chromatin, ribosomes show the complex architecture of each cell in its entirety. Furthermore, a wide variety of cell types shows a corresponding diversity in each 3D image, that in turn can be also modified by environmental, genetic, nutritional factors or even cell to cell interactions.

Finally, such electron microscope images can be colorized in super resolution with protein specific colors in a technique called correlative light and electron microscopy or CLEM. Cell components such as vesicles, membranes, chromatin, lysosomes, etc. can now have an added descriptive dimension based on protein content.

Such complete 3D images of diverse biological systems promise a more direct insight into the incredibly rich mechanisms and the detailed structure of life.

About the Speaker

Harald Hess is an experimentalist who has contributed to several fields across physics and biology.

After a PhD in Physics at Princeton in 1982, Harald Hess pursued hydrogen atom trapping and its Bose-Einstein condensation, BEC, at MIT as a postdoc. There he conceived of evaporative cooling as the means to achieve BEC in atomic gases. At Bell Labs he developed various low temperature scanning probe microscopes to visualize diverse physics phenomenon, such as vortices in superconductors. After 1997 he spent 8 years in industry developing advanced equipment for hard disk drive and semiconductor inspection and production. In 2005 he and a colleague, Eric Betzig, learned about photoactivatable fluorescent proteins and invented PALM (photo-activated localization microscopy) to reveal details of cell structure beyond the diffraction limit. It was built in his La Jolla condo, tested at the National Institute of Health and contributed to the 2014 Nobel Prize in Chemistry. At Janelia Research Campus of Howard Hughes Medical Institute he extended PALM to a 3D super-resolution microscopy and is exploring its application for cell biology research. There he is also developing 3D electron microscopy techniques for volume imaging of cells and neural tissue. Most recently he combined it with cryogenic PALM to correlate with the electron microscope images.

He is member of the National Academy of Sciences and a Fellow of the American Physical Society and the AAAS.