Raw NanoSIMS images from maize leaf for (a) 12C14N, (b) 31P, (c) 32S, (d) 12C14N, (e) the 12C15N/12C14N ratio image (log scale, full data range), (f) 12C15N/12C14N ratio image (log scale, reduced ratio scale maximum), (g) 12C15N/12C14N ratio image (log scale, full data range) and (h) distribution of chloroplast nitrogen isotope ratio values across leaf. Actual ratio values are shown in brackets in the log spectral scale. White arrows point to chloroplasts observed in the image. Red arrow points to cell nucleus. Blue arrow points to example of single bacteria-like structure with exceptionally high nitrogen isotope ratio.