Expert Systems With Applications 55 (2016) 403–416
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Expert Systems With Applications
journal homepage: www.elsevier.com/locate/eswa
Real-time and decision taking selection of single-particles during
automated cryo-EM sessions based on neuro-fuzzy method
David Gil-Carton
a,∗
, Miguel Zamora
a
, James D. Sutherland
c
, Rosa Barrio
c
, Izaskun Garrido
b
,
Mikel Valle
a
, Aitor J. Garrido
b
a
Structural Biology Unit, Cooperative Center for Research in Biosciences CIC bioGUNE, Bizkaia Technology Park, 48160 Derio, Spain
b
Automatic Control Group – ACG, Department of Automatic Control and Systems Engineering, University of the Basque Country (UPV-EHU), 48013 Bilbao,
Bizkaia, Spain
c
Functional Genomics Unit, Cooperative Center for Research in Biosciences CIC bioGUNE, Bizkaia Technology Park, 48160 Derio, Spain
a r t i c l e i n f o
Keyword:
Cryo-electron microscopy
Decision support systems
Fuzzy logic
Image processing
Single-particle analysis
a b s t r a c t
Cryo-electron microscopy (cryo-EM) is a three-dimensional (3D) averaging technique that makes use of
two-dimensional (2D) images of biological macromolecules preserved in a thin layer of vitreous ice. Re-
cent advances in the field have facilitated the evolution of cryo-EM towards atomic resolution, and the
technique provides 3D maps with detailed description of biological macromolecules. Data acquisition at
the transmission electron microscope (TEM) is the first crucial step during the single-particle analysis
workflow in cryo-EM. In order to exploit the potential of this structural technique for atomic or near-
atomic resolution, the initial collection must allow recording of large datasets and, hence, requires op-
erating the TEM in automated mode. The quality of the acquired dataset relies, however, on the exper-
tise of researchers and unsupervised operations might result in low data quality. This work presents the
first expert system integrated in a novel scheme to automate cryo-EM data acquisition in a TEM. This
development takes advantage of fuzzy logic systems to integrate the working mode of an expert in a
linguistic manner and to learn from acquired data through an adaptive network. A new method based
on different image-processing algorithms and on adaptive neuro-fuzzy inference systems (ANFIS) iden-
tifies, in an unsupervised manner, the single-particles present in cryo-EM images during the automated
acquisition on a TEM. This single-particle identification system is integrated in a new intelligent control
scheme to automate cryo-EM data acquisition. A classic fuzzy inference system (FIS) was programmed to
make appropriate decisions during the session. The designed system can be trained for a specific sample
and allows for unsupervised but efficient data collection imitating the working mode of an experienced
microscopist.
© 2016 Elsevier Ltd. All rights reserved.
1. Introduction
In recent years cryo-EM single-particle analysis (Frank, 2006)
has become a high-resolution technique (Kühlbrandt, 2014) due
to the development of direct electron detectors and new proce-
dures in image/video processing (Bai, McMullan, & Scheres, 2015;
Bammes, Rochat, Jakana, Chen, & Chiu, 2012; Campbell et al., 2014;
McMullan, Faruqi, Clare, & Henderson, 2014; Ruskin, Yu, & Grig-
orieff, 2013). Consequently, there is a need for high-throughput
and automation of modern microscopes to generate large datasets
∗
Corresponding author. Tel.: +34 946572516; fax: +34 944061301.
E-mail addresses: dcarton@cicbiogune.es, davidgilcarton@yahoo.es (D. Gil-
Carton), mzamora@cicbiogune.es (M. Zamora), jsutherland@cicbiogune.es (J.D.
Sutherland), rbarrio@cicbiogune.es (R. Barrio), izaskun.garrido@ehu.es (I. Garrido),
mvalle@cicbiogune.es (M. Valle), aitor.garrido@ehu.es (A.J. Garrido).
of images to exploit this potential for near atomic resolution.
Current available methods for automated acquisition in cryo-EM,
such as the commercial EPU (E Pluribus Unum) software, or other
academic software packages (Carragher et al., 2000; Zhang et al.,
2009), allow collecting images from pre-selected areas. However,
none of these softwares makes decisions during an automated
session according to the quality of the cryo-EM images being
recorded. Until now, the automatic evaluation of the data being
collected during cryo-EM data acquisition sessions has not been
available and, in the case of an unsupervised TEM session, the final
output might be of poor quality. The presence of contamination, an
inadequate ice thickness, empty holes due to broken carbon film,
aggregation, poor concentration of particles, or damaged speci-
mens, might severely reduce the final size of useful dataset. In this
context, the development of new intelligent control schemes that
imitates the behavior of expert researchers during cryo-EM data
http://dx.doi.org/10.1016/j.eswa.2016.02.018
0957-4174/© 2016 Elsevier Ltd. All rights reserved.