¹⁴N and ¹⁵N imaging by SIMS microscopy in soybean leaves

The distribution of ¹⁵N and ¹⁴N compounds in cryofixed and resin embedded sections of soybean (Glycine max L) leaves was studied by SIMS microscopy. The results indicate that, with a mass resolution M/ΔM higher than 6000, images of the nitrogen distribution can be obtained from the mapping of the two secondary cluster ions ¹²C¹⁴N− and ¹²C¹⁵N−, in samples of both control and ¹⁵N^-labeled leaves. The ionic images were clearly related to the histological structure of the organ, and allow the detection of ¹⁴N and ¹⁵N at the subcellular level. Furthermore, relative measurements of the ¹²C¹⁴N− and ¹²C¹⁵N− beams made possible the quantification of the ¹⁵N atom% in the various tissues of the leaf. (author)