ABSTRACT
We are requesting funds to acquire a Thermo Fisher Scientific integrated Cryo-Electron Microscopy (Cryo-
EM) imaging system (Imaging Energy Filter/Direct Electron Detector) that will upgrade cryo-EM capabilities
at the University of Colorado Anschutz School of Medicine Cryo-Electron Microscopy Facility (AnCEM).
AnCEM, established in 2016 to enable cryo-EM research on the Anschutz campus and beyond, is backed by
strong institutional support from the Anschutz School of Medicine, the Colorado University Cancer Center
(UCCC), and the Colorado Clinical and Translational Sciences Institute (CCTSI). The centerpiece of the
facility is a Thermo Fisher Scientific 200kV Talos Arctica transmission electron microscope (TEM) equipped
with an X-FEG electron source, a phase contrast plate and a Gatan K3 Summit direct electron detector (DED).
The facility also counts with a Talos L120C TEM used for cryo-screening and imaging of stained specimens,
and with all ancillary equipment required to carry out biomolecular cryo-EM studies. A total of ~50 cryo-EM
scientist from ~20 NIH-supported research groups on campus depend on AnCEM for cryo-EM specimen
preparation, optimization and screening, and for high-resolution data collection. Over the last 6 years,
AnCEM has generated preliminary data for ~20 current NIH-funded grants and generated data included in
many peer-reviewed publications.
AnCEM’s current imaging capabilities are limited by the lack of an imaging energy filter and by sub-optimal
integration of our DED with the Talos Arctica TEM. This has a direct, negative impact on cryo-EM data quality
and data collection efficiency, and severely limits our options for selecting automated imaging software on
which all data collection depends. These limitations hinder AnCEM’s ability to support cryo-EM research on
campus and beyond and compromise the facility’s long-range viability. The proposed imaging system
upgrade will allow AnCEM to deliver considerably better cryo-EM data at a much faster rate (effectively
reducing data collection time and cost about 3-fold) and allow AnCEM to continue to drive cryo-EM research
in Denver and the surrounding area, and to provide essential support to a large number of NIH-funded
projects.
Regional institutional facilities like AnCEM play an essential role in enabling cryo-EM research, but they must
keep up with technological developments to remain relevant and properly fulfill their essential role in getting
cryo-EM projects off the ground and complementing data collection resources offered by larger national
Cryo-EM facilities. The capabilities of 200kV TEMs have been re-evaluated over the last few years and it is
now widely acknowledged that these instruments, which are comparatively cheaper to install and maintain,
can be used to determine structures of well-behaved biomolecules at better than 2Å resolution, and to
deliver high-quality cryo-electron tomography (Cryo-ET) data. The optics and intrinsic imaging capabilities of
our Talos Arctica are comparable to those of the newest 200kV TEMs. Therefore, upgrading the imaging
capabilities of our Talos Arctica will address imaging limitations, and dramatically enhance services offered
by AnCEM in the most rational and economically-efficient way. The proposed imaging upgrade is essential to
support the specific aims of NIH-funded research, and to meet evolving needs of cryo-EM researchers in the
CU Anschutz Medical School and beyond. The proposed upgrade will also set the stage for future
implementation of large-scale 3D imaging and Cryo-ET on the Anschutz campus.