B24 is a dedicated biology beamline that bridges the gap between electron microscopy and conventional light microscopy. Currently in optimisation mode, the full-field X-ray microscope allows whole cells to be rapidly imaged in great detail. Users can study all aspects of cellular structure, including gross changes resulting from the effects of, for example, drugs, disease, and parasites.
B24 is designed specifically to meet the rising demand for tomographic imaging of biological specimens under near physiological conditions and to bridge the resolution gap between electron microscopy and conventional light microscopy. The beamline can be used for collecting data on cells, but bacteria and lipid structures, amongst other things, can also be studied.
At present B24 is operating in the water window – an X-ray energy range where water/ice is relatively transparent (unlike carbon and other elements found in biological specimens, which are strongly absorbed). As a result, natural contrast occurs enabling imaging in as close to the native state as possible. In future it is planned to extend the beamline’s operation to higher X-ray energies, which will allow, amongst other things, data to be collected on thicker specimens.
Software development
Software engineers at Diamond are collaborating with Nottingham University’s Computer Vision department to accelerate the segmentation of 3D data from B24. The process involves classifying all the cell components in the data, which, if successful, will significantly reduce the analysis time from weeks to days. On completion this software will be available for use on data from other experiments, not just B24.
Correlative Microscopy
The super-resolution light microscopy facility at B24 is being developed and constructed as part of a collaboration with the University of Oxford (Micron, NanO, Engineering Department, StruBi). It aims to provide facilities to collect super-resolution data on vitrified samples using either SIM or dSTORM prior to moving these same samples to the X-ray microscope for tomographic data acquisition. Correlation of the data collected using the different imaging modalities available on B24 will enhance the depth of information obtained. This will result in a greater understanding of the science question originally posed.
To find out more about B24, contact the Principal Beamline Scientist, Dr Liz Duke: elizabeth.duke@diamond.ac.uk
A human fibroblast cell infected with Toxoplasma gondii. A view of four T. gondii parasites within their parasitophorous vacuole (yellow) with part of the surrounding fibroblast. Individual parasite features such as cell membranes (cyan), nuclei (red), rhoptries (green), and granules (blue) are visible. Image created by Katja Ota (Birkbeck), Vern Carruthers (Univ of Michigan, Ann Arbor) and Helen Saibil (Birkbeck).
“B24 has given us a unique opportunity to look at the 3D structure of frozenhydrated human cells infected with malaria or Toxoplasma parasites, without any sectioning. We've been able to image intact cells, far thicker than we can examine by electron microscopy, and resolve the membrane structures that the parasites aim to break through when ready to exit their host cell.”
Professor Helen Saibil, Birkbeck College London
Carzaniga R, et al. Cryo-soft X-ray tomography: A journey into the world of the native-state cell. Protoplasma 251(2), (2014).
Duke EM, et al. Biological applications of cryo-soft X-ray tomography. J Microsc. 255(2), (2014).
Duke EM, et al. Imaging endosomes and autophagosomes in whole mammalian cells using correlative cryo-fluorescence and crysoft X-ray microscopy (cryo-CLXM). Ultramicroscopy 143 (2014).
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