Breakthrough Technology: Soft X-ray imaging of cellular carbon and nitrogen distributions in cyanobacteria (Plant Phys)

Soft X-ray imaging is a promising new technology that can be used to measure elemental compositions of living cells. By adjusting the energy (wavelength) of the incident X-rays, it is possible to specifically measure C or N, which have different photo-absorption edges.  Teramoto et al. demonstrate the power of soft X-ray microscopy (SXM) by imaging carbon and nitrogen levels in distinct cell types of the nitrogen-fixing photosynthetic cyanobacterium Anabaena sp. PCC 7120. When nitrogen is limiting, certain cells differentiate into nitrogen-fixing heterocysts, which exchange the resulting N-rich compounds for C-rich compounds produced by the photosynthetic vegetative cells. Using SXM, the authors were able to quantify C, N, and C/N ratios in the two cell types. The authors observe that this method can be applied to other systems for example to study oil-producing algae and algal carbon-concentrating structures. (Summary by Mary Williams) Plant Physiol. 10.1104/pp.17.01767