Journal of Plant Research

, Volume 132, Issue 3, pp 431–438 | Cite as

Absorbance spectra of the hematochrome-like granules and eyespot of Euglena gracilis by scan-free absorbance spectral imaging A(x, y, λ) within the live cells

  • Kyohei Yamashita
  • Takafumi Yagi
  • Takumi Isono
  • Yusuke Nishiyama
  • Masafumi Hashimoto
  • Koji Yamada
  • Kengo Suzuki
  • Eiji TokunagaEmail author
Regular Paper


Euglena gracilis has an organelle resembling hematochrome, with an appearance similar to the eyespot and the absorption band spectrally overlapped with that of the carotenoid. To discriminate the hematochrome-like granules and eyespot, scan-free, non-invasive, absorbance spectral imaging A(x, y, λ) microscopy of single live cells, where A(x, y, λ) means absorbance at a position (x, y) on a two-dimensional image at a specific wavelength λ was applied. This technique was demonstrated to be a powerful tool for basic research on intracellular structural analysis. By this method, characteristic absorption spectra specific to the hematochrome-like granule or eyespot were identified among a variety of spectra observed depending on the location inside the organelles. The hematochrome-like granule was dark orange and deep green in its outline and had a characteristic absorption peak at 620 nm as well as at 676 to 698 nm, suggesting that its origin is a component of chloroplast including chlorophyll a. Furthermore, the representative spectra of these organelles were derived by principal component analysis of the absorbance and its position in absorbance image, indicating that they can be distinguished from each other and other regions. It was also confirmed that even in areas where these organelles and chloroplasts overlap, one can distinguish them from each other. The present research clarified the absorption spectra of the eyespot with 1 × 1 µm spatial resolution and those unpublished of hematochrome-like granules of E. gracilis, and indicated that one can statistically distinguish these organelles by this method.


Euglena Eyespot Hematochrome-like granule Carotenoid Chloroplast Absorbance spectral imaging Photosynthesis Alga Microscopy Principal component analysis 



The authors would like to thank Research Center for Green and Safety Sciences, Tokyo University of Science for financial support.

Supplementary material

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Supplementary material 3 (PDF 1089 KB)
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Supplementary material 4 (PDF 271 KB)


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Copyright information

© The Botanical Society of Japan and Springer Japan KK, part of Springer Nature 2019

Authors and Affiliations

  1. 1.Department of Physics, Faculty of ScienceTokyo University of ScienceTokyoJapan
  2. 2.euglena Co., Ltd.Yokohama-shiJapan

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