A. Fluorescence micrograph of a coral polyp, showing autofluorescence of the coral tissue (green) and the photosynthetic Symbiodinium algae living inside (red). To image these photosensitive corals, a custom light-sheet microscope was made. This image won the 2019 Nikon Small World in Motion Competition, and method details can be found in Laissue et al. (2019).

B. Fluorescence micrograph of the diatom Thalassiosira nanae. Chloroplasts are red, neutral lipids green, DNA blue and the cell wall white. Fluorescence microscopy provides three-dimensional information of individual components, enabling the measurement of their volumes. For more information, see Chansawang et al. (2016).

C. Fluorescence in situ hybridization image of coral reef biofilms using confocal microscopy. Samples were hybridized with the Cy5-labelled Bacteria-specific probe (EUB338), the Cy3-labelled GAM42a (for Gammaproteobacteria), the fluorescein-labelled ALF1b (for Alphaproteobacteria) and the Cy3-labelled Arch915 (for Archaea). Cells which appear magenta are Gammaproteobacteria, cyan cells are Alphaproteobacteria, blue cells are other Bacteria, and red cells are Archaea. Large autofluorescent algal filaments can also be observed interspersed with the smaller bacterial and archaeal cells. The scale bar is 100 µm.

D. Helium ion microscopy image showing T4 phage infecting E. coli. Some of the attached phage have contracted tails indicating that they have injected their DNA into the host. The bacterial cells are ~ 0.5 µm wide, equivalent in size to the small dots seen in C. For more information, see Leppänen et al. (2017).

• Laissue, P.P., Gu, Y., Qian, C., and Smith, D.J. (2019) Light-induced polyp retraction and tissue rupture in the photosensitive, reef-building coral Acropora muricata. BioRxiv. https://doi.org/10.1101/862045
• Chansawang, N., Geider, R.J., Obara, B., and Laissue, P.P. (2016) Three-dimensional visualization and quantification of lipids in microalgae using fluorescence microscopy. In Hydrocarbon and Lipid Microbiology Protocols: Ultrastructure and Imaging. McGenity, T.J., Timmis, K.N., and Nogales, B. (eds). New York, NY, USA: Springer, pp. 145–161.
• Leppänen, M., Sundberg, L.-R., Laanto, E., de Freitas Almeida, G.M., Papponen, P., and Maasilta, I.J. (2017) Imaging bacterial colonies and phage-bacterium interaction at sub-nanometer resolution using helium-ion microscopy. Adv Biosyst 1: 1700070.