Synchrotron-based infrared imaging of Euglena gracilis single cells.

Infrared (IR) microspectroscopy is used to examine and identify the chemistry in individual living cells of Euglena gracilis. The spectra provide relative concentrations of lipids, proteins and carbohydrates in the specimen. Diffraction-limited, spatially resolved IR images of single cells of the microalga were measured using synchrotron radiation as a bright IR source. These contour maps reveal the distributions of the proteins, lipids and carbohydrates including the phospholipids, sugars and paramylon. We compare the images with the biochemistry for E. gracilis. We also present the IR images for two different cells, which were exposed to different culture conditions prior to the measurements. The overall trends observed for the two specimens are in qualitative agreement with the hypothesis that there was a significantly reduced concentration of nitrogen in the culture as a function of time. Importantly, this study demonstrates the potential to examine changes in the chemistry of living cells while modifying environmental stimuli.