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from fi elds and vibration, as well as introducing tight control of the room air fl ow, air temperature and humidity. These many years of work involving a broad and highly-skilled team have delivered extremely ‘quiet’ rooms that enable the most advanced microscopy in an extremely challenging site in central London.
“The Electron Microscopy Science Technology Platform (EM STP) is now operational, containing an impressive suite of microscopes, from confocal and cryo-fl uorescence light microscopes, to benchtop SEMs, an integrated light and SEM, several Serial Block Face SEMs, a Focused Ion Beam SEM, two 120 kV TEMs and a micro CT system. Alongside the microscopes sits a full suite of sample preparation equipment, including coaters, plunge freezers, a high pressure freezer, freeze substitution units, ultramicrotomes and cryo- ultramicrotomes. This means that we can pick and choose the best tool for answering a particular biological question, often combining microscopes into correlative workfl ows, which enable us to image different types of information from a single sample across scales.
“The primary focus of the EM STP is to collaborate with Crick scientists to image their samples and shed light on their biological questions. Recent collaborations have seen us study proteins binding to DNA in a study of DNA repair mechanisms relevant to both breast and ovarian cancer with Simon Boulton’s lab; a study of Mycobacterium tuberculosis infection in human lymphatic endothelial cells with Max Gutierrez’s lab; and a study of HIV assembly within human macrophages with Mark Marsh at one of our partner universities, UCL. These are just three of 40-60 projects that we have running at any one time. At steady state, the Crick will have 120 research groups, so it is likely this workload could double or even triple in the near future.
“All of this work, as well as our own activity in designing and building new light microscopes to integrate with electron microscopes for advanced correlative microscopy, is handled by a team of ten post-doctoral research scientists. With PhDs in either the biological or physical sciences, each member of the team is capable of working across a
FEI BioTwin T12 12-kV TEM Zeiss Sigma FEG SEM with Gatan 3View
broad range of techniques and technology applied to the Crick research projects, whilst developing new techniques and technologies, also keeping the complex and demanding equipment running smoothly. Meanwhile, we also collaborate with leading imaging labs across the world to develop and apply new imaging techniques to Crick science. A major ongoing collaboration sees us working with Liz Duke at the Diamond Light Source in Oxfordshire, Eva Pereiro at the ALBA synchrotron in Barcelona and Gerd Schneider at the BESSY II synchrotron in Berlin, to image whole frozen cells at high resolution and as close to their living state as possible.
“Perhaps the most exciting and impressive part of the new Crick building, apart from its scale and position, is the provision of countless collaboration spaces, beautifully designed to provide areas for scientists to come together and relax with each other and with external academics and commercial collaborators, creating the space and opportunity to explore the most exciting interdisciplinary ideas. Comfortable sofas and booths with AV equipment hang on bridges across the enormous atrium, and coffee stations come equipped with glass walls that can be moved to create an impromptu meeting area, written on and then photographed and emailed as a record of the brain-storming session. A 400-seat auditorium nestles in the atrium space alongside multiple breakout areas and a public exhibition space, bringing our science to the local area and an international audience travelling through St. Pancras station next door.
Research Scientists Chris Peddie and Rafaella Carzaniga looking at images from the FIB SEM
“After a decade of planning and building, we are extremely excited about the advances that will be enabled by this unique building and it’s occupants, over the next ten years and beyond. I don’t think there is a better place to discover how life works at the smallest of scales.”
Cryomicroscopy shows how fl u virus fuses with host cell
Scientists at the Francis Crick Institute have visualised how the infl uenza virus fuses with the membrane of a host cell. This is an essential step in the virus’s lifecycle and the fi ndings could lead to new approaches to prevent infection.
Peter Rosenthal of the Crick said: “The infl uenza virus is an important human pathogen and understanding all the steps in its lifecycle are important for understanding virus infection. Entry into the host cell is a key step in virus infection.
“During infection, the virus delivers its genome into the host cell by fusing its own lipid membrane with that of the host cell membrane. This process is achieved by structural changes in the hemagglutinin, which is one of two protein spikes on the virus surface. The hemagglutinin spikes insert into host cell target membrane and mediate the close approach and fusion of membranes.”
Lesley Calder, the fi rst author of the study, used cryomicroscopy, a high-resolution imaging method, to observe how the virus fuses with a target membranes in the laboratory.
Cryomicroscopy images biological structures in a frozen-hydrated state that preserves high-resolution features. Images are then acquired via an electron microscope using minimal electron exposure so that the electrons do not damage the structures of interest. This technique allowed the scientists to record images from many angles and to calculate 3D maps of the virus fusing with the target membranes. The 3D maps, combined with information from previous biochemical and structural studies, provide an explanation of how membrane fusion occurs.
Dr Rosenthal said: “By imaging at high-resolution the way the virus fuses with a membrane, we can learn how the viral proteins and their structural changes bring about membrane fusion. The more detailed understanding of this process identifi es steps that could be blocked and may therefore provide new targets for drugs designed to inhibit these steps in the future.”
The paper, ‘Cryomicroscopy provides structural snapshots of infl uenza virus membrane fusion’, is published in Nature Structural and Molecular Biology.
Infl uenza virus fusing with target membrane called a liposome. Picture credit: Lesley Calder and Peter Rosenthal
• Francis Crick Institute scientists have used cryomicroscopy to visualise how the infl uenza virus fuses with the membrane of a host cell.
• Flu viruses are categorised into types A, B and C. Type A viruses are the source of seasonal and pandemic fl u outbreaks and are categorised depending on two proteins on their surface - called haemagglutinin and neuraminidase. The haemagglutinin is responsible for the fl u virus binding to host cells, followed by the delivery of the virus’s genome to the inside of the cell where it multiplies. Our main antibody response is directed against haemagglutinin.
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