English: The scary faces of wood. The set of popper wood samples were treated with the catalyst (increasing incubation time in the set of images) in order to optimise the extraction of lignin polymers. Slices of 10 um thickness were cut with a microtome, mounted on slides, and imaged with a multicolour fluorescence microscope with laser excitation lines between 405 and 638 nm (four pseudo-coloured channels in the images). Temporal stacks of images (200 images/channel at 10 Hz) were generated with a 1.49 N.A. objective (Olympus) and an iXon Ultra 897 EMCCD camera (Andor) cooled to -100°C; and analysed with the Super-Resolution Radial Fluctuation (SRRF) algorithm. The summary magnification of the images was 600x (pixel size 26.7 nm). For the majority of the images, Fourier ring correlations (FRCs) indicates a minimum resolution of less than 60 nm (below the diffraction limit of optical microscopy). This allows the observation of individual lignin fibers in the cell walls. The change in intensity and colour across the series of images indicates the initial increase in the degree of conjugation in the polymer (the change from blue to red) with the subsequent extraction of products (the decrease in overall intensity and loss of cell wall stiffness).

English: Super-resolution fluorescence microscopy image of popper wood cells (4-th image in set)