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Updated: Feb 12, 2026

3D Imaging of Soft-Tissue Samples using an X-ray Specific Staining Method and Nanoscopic Computed Tomography
Published on: October 24, 2019
Soft X-Ray Imaging of Cellular Carbon and Nitrogen Distributions in Heterocystous Cyanobacteria
Takahiro Teramoto1, Chihiro Azai2, Kazuki Terauchi2
1College of Science and Engineering, Ritsumeikan University, Kusatsu 525-8577, Japan tteramo@fc.ritsumei.ac.jp.
Abstract:
Soft x-ray microscopy (SXM) is a minimally invasive technique for single-cell high-resolution imaging as well as the visualization of intracellular distributions of light elements such as carbon, nitrogen, and oxygen. We used SXM to observe photosynthesis and nitrogen fixation in the filamentous cyanobacterium Anabaena sp. PCC 7120, which can form heterocysts during nitrogen starvation. Statistical and spectroscopic analyses from SXM images around the K-absorption edge of nitrogen revealed a significant difference in the carbon-to-nitrogen (C/N) ratio between vegetative cells and heterocysts. Application of this analysis to soft x-ray images of Anabaena sp. PCC 7120 revealed inhomogenous C/N ratios in the cells. Furthermore, soft x-ray tomography of Anabaena sp. PCC 7120 revealed differing cellular C/N ratios, indicating different carbon and nitrogen distributions between vegetative cells and heterocysts in three dimensions.
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