Lattice Light Sheet Microscopy for the Biosciences

To understand how cells and organisms function, researchers use a wide range of microscopes to 'see' inside them. Typically, we will use a fluorescent marker to label a protein inside a cell, and then use a fluorescent microscope to see how the protein is organised, and how this might change with time. This is really important in framing our ideas about how a protein functions. Most microscopes shine fluorescent light on the entire cell (or organism) but only image a small part of it. Unfortunately, cells are sensitive to light, and this approach often damages the cell as we look, and cells can die as we try to image them. To overcome this problem, we plan to use a new type of microscope, which only shines light in a single narrow plane across the cell (or organism), and we only image this illuminate region. This approach greatly reduces the amount of light that the cell experiences, which is much less damaging to the cell, and allows us to image living cells for much longer without affecting their behaviour, compared to other kinds of microscopes. The plane of light that this type of 'light sheet' microscope generates is very thin (about half a micron), much thinner than cells (which are about 20 microns thick), which not only reduces the amount of light that the cell experiences, but also helps us to image them with a high amount of detail. This new microscope also helps us to image rapidly, at about 50 times a second, so that rapid changes in behaviour are captured. The objective used to generate this thin plane of light and the objective used to image the fluorescence within it are both placed below the sample, which makes if easy for us to grow cells in dishes and place them straight onto the microscope to image them. Overall, this new microscope will help us see how specific proteins play a role in mitosis, and drive diseases such as cancer, investigate how cells differentiate into muscle, and into other forms of tissue, such as the retina, using balls of cells (organelles), understand how plants sense gravity, signalling in sensory neurones, how cells secrete their contents and how organisms sense stress. It will support a wide range of additional research across the University of Leeds, and in the Yorkshire region.

Light sheet microscopy has been a key advance in our ability to image cells, tissues and organisms with much reduced phototoxicity. There are many different types of light sheet available commercially, which typically vary in the type of light sheet generated. For example, in the Bioimaging facility at the University of Leeds, we have an LAVision light sheet microscope (UltraMicroscope), which is most suited for large tissue samples and whole organs such as heart and brain, most usually after fixation and clearing, where the thickness of the light sheet can be varied from 4 to 24 microns. For light sheet imaging of cultured cells, organoids and small organisms such as C. elegans, an instrument that generates a much narrower light sheet is needed. Here we plan to install a newly released lattice light sheet (LLS) microscope from Zeiss, which uses a coherent array of Bessel beams to form the light sheet (down to 500nm in width), much reducing out of focus excitation while providing high resolution (up to 290nm x 290nm resolution in xy, and 450nm in z) imaging at a typical image capture rate of 50 frames per second. Moreover, this has been implemented in an inverted microscope format, which is novel for light sheet microscopes, and has been engineered to make the instrument easy to use, easy to set up (and align the light sheet) and ideally suited for installation into a shared microscope facility for multi-users. It will support the research of multiple groups that already use our facility across the university, from plant research to organoids and C.elegans, and is of great interest to many users from across the Yorkshire region from Newcastle to Huddersfield and Sheffield.