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Research on Electronic cryo-microscopy is coming to life at the University of Milan and the Invernizzi Centre22-02-2018

It's a busy time for the electronic cryo-microscopy laboratory, managed by Martino Bolognesi, who offers the possibility of conducting research on 3D structures of biological macro-molecules to laboratories and research centres both inside and outside the University.

Analisi della macro-molecola nel laboratorio di crio-microscopia elettronicaThe electronic cryo-microscope of the University of Milan - La Statale and the 'Romeo and Enrica Invernizzi' Paediatric Research Centre is called FEI Talos Arctica 200 kV FEG-Falcon3 and is dedicated to the study of the 3D structure of biological macro-molecules with quasi-atomic resolution.

From January 2018, the super microscope has been fully operational and offers opportunities to conduct studies and investigation in laboratories and research facilities which are also external to the University, both in Italy and abroad, in the field of bio-chemistry, molecular biology, biophysics, genetics, virology and immunology.

The purchase of the equipment was decided upon in April 2016 with a joint financing of 3 million Euro provided by the University of Milan - La Statale and the Invernizzi Centre, this was just before electronic cryo-microscopy became a buzzword in scientific press thanks to the awarding of the 2017 Nobel Prize for Chemistry to Jacque Dubochet, Joachim Frank and Richard Henderson.

In Italy, the FEI Talos is the only electronic cryo-microscope of its kind and, for the University in via Festa del Perdono and the Invernizzi Research Centre, it is an example of a forward-looking investment capable of aligning university research to the highest international standards.

Martino Bolognesi states that "with the FEI Talos electronic cryo-microscope, we can observe a biological sample with a resolution of approximately 3 Å (Angstrom), which means the ability to distinguish structural details of sizes close to the atom-atom distances in macromolecules, to reconstruct amino-acids and secondary structures in proteins, or nucleotides in nucleic acids".

What makes the electronic cryo-microscope a super machine capable of looking into the eyes of DNA?

To understand this, we have to look at the history of the last 50-80 years of research in the field of structural biology, the field of bio-chemistry and bio-physics which studies the 3D structure of macro-molecules such as proteins and nucleic acids, starting with the first prototype of an electron microscope made by Knoll and Ruska (1931), moving onto the X-ray crystallography of Perutz and Kendrew (1960) and the studies of the three Noble prize winners for Chemistry in 2017.Il professor Bolognesi e il Talos FEI

According to Professor Bolognesi, "in essence, the functioning principles of an electronic cryo-microscope are similar to those of an optical microscope; it differs only for the use of electrons instead of a ray of light, for the sample preparation methods and retrieving the signal captured by special detectors".

With regard to the treatment of the sample to be analysed, a problem that the researchers try to minimise in electronic cryo-microscopy is the damage that the ray of electrons can cause to the macro-molecules under study, "bombarded" by a ray of charged particles with high energy under very high-pressure conditions.

To compensate for this important aspect, two main experimental expedients, fruit of the studies of Dubochet, Frank and Henderson are used: a) the cryo-freezing of the sample (the so-called "vitrification" in which the sample is taken very quickly to temperatures close to those of liquid nitrogen), b) the use of Direct Electron Detectors, super-sensitive state-of-the-art sensors which manage to detect flows of few electrons/seconds per pixel (a result which is almost at the limit of quantistic uncertainty) and which allow to irradiate the sample with very mild doses of electrons.

Paolo Swuec e Martino BolognesiFurthermore, in order to make the most of some of the aspects of image acquisition and its processing, the detector on the Talos operates with a time resolution of 40 images/second: 40 micrographs per second for an experiment which can last many hours means thousands of images acquired by electronic cryo-microscopy during a single experiment, a bulk of "shots" that are then analysed and combined according to the orientation of the macro-molecules, with high loads both for the calculation and for the archiving of the images.

According to Professor Bolognesi, "to deal with this amount of data, the electronic cryo-microscope uses servers based on multiple GPU units (Graphic Processing Unit), an evolution of the classic CPUs (Central Processing Unit), which allow to elaborate high-resolution 3D maps with high-speed calculation. Currently, our electronic cryo-microscope has only one server with 2 GPUs, but in the next few months we'll have a 16 GPU server, with a storage capacity of about 650 terabytes".

There are many applications of electronic cryo-microscopy in research, including an important number of studies aimed at understanding the mechanisms of action of pharmaceuticals.

Professor Bolognesi says that "in structural biology, the basic study of proteins and nucleic acids also means analysing how a new molecule (potential pharmaceutical), which is being developed can amend or be recognised by the structure of the protein/receptor to which it binds itself. All of this, with the great advantage that thanks to electronic cryo-microscopy, allows us to use small quantities of samples potentially extractable live, complexes with multiple components which are extremely difficult to reconstruct in vitro, or membrane proteins".

Together with Paolo Sweuc, a post-doc researcher from the Francis Crick Institute (London), Professor Bolognesi is currently conducting research in the pathological and vegetation sectors for projects within the University and for external bodies.


Project Design, Sample Optimization, Negative Staining Electron Microscopy, Cryo-Electron Microscopy/Tomography and Data Analysis are the services of electronic cryo-microscopy offered by Professor Bolognesi's laboratory to groups and research bodies which are both internal and external to the University. More details can be retrieved on the 'Romeo and Enrica Invernizzi' Paediatric Research Centre website.



Per informazioni
The University of Milan
Department of Biosciences
Prof. Martino Bolognesi
Phone +39 02 503 14893 - 14892- 14894