Radiation dose reduction and image enhancement in biological imaging through equally-sloped tomography.
Electron tomography is currently the highest resolution imaging modality available to study the 3D structures of pleomorphic macromolecular assemblies, viruses, organelles and cells. Unfortunately, the resolution is currently limited to 3-5nm by several factors including the dose tolerance of biological specimens and the inaccessibility of certain tilt angles. Here we report the first experimental demonstration of equally-sloped tomography (EST) to alleviate these problems. As a proof of principle, we applied EST to reconstructing frozen-hydrated keyhole limpet hemocyanin molecules from a tilt-series taken with constant slope increments. In comparison with weighted back-projection (WBP), the algebraic reconstruction technique (ART) and the simultaneous algebraic reconstruction technique (SART), EST reconstructions exhibited higher contrast, less peripheral noise, more easily detectable molecular boundaries and reduced missing wedge effects. More importantly, EST reconstructions including only two-thirds the original images appeared to have the same resolution as full WBP reconstructions, suggesting that EST can either reduce the dose required to reach a given resolution or allow higher resolutions to be achieved with a given dose. EST was also applied to reconstructing a frozen-hydrated bacterial cell from a tilt-series taken with constant angular increments. The results confirmed similar benefits when standard tilts are utilized.
Lee
Edwin
E
Department of Physics and Astronomy, University of California, Los Angeles, CA 90095, USA.
Fahimian
Benjamin P
BP
Iancu
Cristina V
CV
Suloway
Christian
C
Murphy
Gavin E
GE
Wright
Elizabeth R
ER
Castaño-Díez
Daniel
D
Jensen
Grant J
GJ
Miao
Jianwei
J
D001419:Bacteria / Q000648:ultrastructure; D004867:Equipment Design; D005615:Freezing; D006433:Hemocyanins / Q000737:chemistry; D007091:Image Processing, Computer-Assisted / Q000379:methods; D011829:Radiation Dosage; D014057:Tomography, X-Ray Computed / Q000295:instrumentation* / Q000379:methods
D006433:Hemocyanins; C032808:keyhole-limpet hemocyanin
J Struct Biol. 2003 Dec;144(3):301-12
14643198
Q Rev Biophys. 1988 May;21(2):129-228
3043536
Nature. 1968 Jan 13;217(5124):130-4
23610788
Proc Natl Acad Sci U S A. 2005 Oct 25;102(43):15343-6
16219701
Med Biol Eng Comput. 1988 Mar;26(2):186-92
3226174
J Struct Biol. 2007 Jan;157(1):288-95
17029985
J Struct Biol. 2006 Mar;153(3):231-40
16427786
Ultramicroscopy. 1998 Apr;72(1-2):53-65
9561797
Science. 1974 Dec 13;186(4168):1036-7
4469695
Mol Biol Cell. 2004 Mar;15(3):957-62
14699066
J Opt Soc Am A Opt Image Sci Vis. 2004 Apr;21(4):499-509
15078020
Ultramicroscopy. 1984;13(1-2):57-70
6382732
Curr Opin Struct Biol. 2007 Apr;17(2):260-7
17398087
Annu Rev Phys Chem. 2008;59:387-410
18031219
Q Rev Biophys. 1995 May;28(2):171-93
7568675
N Engl J Med. 2007 Nov 29;357(22):2277-84
18046031
J Cell Biol. 2001 Jun 11;153(6):F25-32
11402057
Annu Rev Biochem. 2005;74:833-65
15952904
J Struct Biol. 2001 Feb-Mar;133(2-3):156-69
11472087
J Struct Biol. 2001 Sep;135(3):239-50
11722164
J Struct Biol. 1997 Dec;120(3):343-52
9441937