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

Yagi, Takanori; Isono, Takumi; Nishiyama, Yusuke; Hashimoto, M; Yamada, Koji; Suzuki, Kengo; Tokunaga, Eiji

doi:10.1007/s10265-019-01102-0

Cited by 3 publications

(6 citation statements)

References 25 publications

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“…Detailed methods of scan-free absorbance spectral imaging were previously described (Isono et al, 2015) and the subsequent improvement was reported recently (Yamashita et al, 2018; Yamashita et al, in press). Here we give only brief specifications.…”

Section: Methodsmentioning

confidence: 99%

Noninvasive and safe cell viability assay forEuglena gracilisusing natural food pigment

Yamada¹,

Suzuki²,

Tokunaga

2019

PeerJ

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Noninvasive and safe cell viability assay is required in many fields such as regenerative medicine, genetic engineering, single-cell analysis, and microbial food culture. In this case, a safe and inexpensive method which is a small load on cells and the environment is preferable without requiring expensive and space-consuming equipment and a technician to operate. We examined eight typical natural food pigments to findMonascuspigment (MP) or anthocyanin pigment (AP) works as a good viability indicator of dye exclusion test (DET) forEuglena graciliswhich is an edible photosynthetic green microalga. This is the first report using natural food pigments as cell viability assay.Euglena gracilisstained by MP or AP can be visually judged with a bright field microscope. This was spectrally confirmed by scan-free, non-invasive absorbance spectral imagingA(x, y,λ) microscopy of single live cells and principal component analysis (PCA). To confirm the ability of staining dead cells and examine the load on the cells, these two natural pigments were compared with trypan blue (TB) and methylene blue (MP), which are synthetic dyes conventionally used for DET. As a result, MP and AP had as good ability of staining dead cells treated with microwave as TB and MB and showed faster and more uniform staining for dead cells in benzalkonium chloride than them. The growth curve and the ratio of dead cells in the culture showed that the synthetic dyes inhibit the growth ofE. gracilis, but the natural pigments do not. As the cell density increased, however, AP increased the ratio of stained cells, which was prevented by the addition of glucose. MP can stain dead cells in a shorter time than AP, while AP is more stable in color against long-term irradiation of intense light than MP. Due to the low toxicity of these pigments, viability of cells in culture can be monitored with them over a long period.

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Section: Methodsmentioning

confidence: 99%

Noninvasive and safe cell viability assay forEuglena gracilisusing natural food pigment

Yamada¹,

Suzuki²,

Tokunaga

2019

PeerJ

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“…Regardless of the type of culture medium and light amount, the absorption peak of Chl- a (680 nm) is significantly smaller in height compared to the control, with a broad absorption peak (420~500 nm) presumably originating from carotenoids. Furthermore, when compared with the absorption spectra of the “Eyespot” and “Haematochrome-like granules (HCs)” within E. gracilis cells [ 30 ], the spectrum of the reddened cells showed a similarity to that of the “Eyespot”, which predominantly contains carotenoids.…”

Section: Resultsmentioning

confidence: 99%

“…The eyespot in E. gracilis is an organelle concentrated with carotenoids, including diadinoxanthin, diatoxanthin, and β -carotene [ 54 , 55 ]. HC, while resembling the eyespot in appearance, has a different absorption spectrum [ 30 ]. In Figure 6 , data from our previous paper [ 30 ] have been recompiled to show these absorption spectra (“Eyespot(CM*)”, “HC(CM*)”).…”

Section: Discussionmentioning

confidence: 99%

“…HC, while resembling the eyespot in appearance, has a different absorption spectrum [ 30 ]. In Figure 6 , data from our previous paper [ 30 ] have been recompiled to show these absorption spectra (“Eyespot(CM*)”, “HC(CM*)”). The absorption spectrum of HC is clearly different from that of the reddened cells.…”

Section: Discussionmentioning

confidence: 99%

“…Aiming to expand the industrial use of E. gracilis for food purposes, we have established a spectroscopic method for identifying carotenoids and hematochrome-like granules (structures resembling the eyespot but suggested not to contain carotenoids [ 29 ]) within single cells [ 30 ]. Additionally, we have developed an efficient cultivation method by growing it in foods, such as tomato juice beverages [ 31 ].…”

Section: Introductionmentioning

confidence: 99%

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Reddening of the Unicellular Green Alga Euglena gracilis by Dried Bonito Stock and Intense Red Light Irradiation

Yamashita,

Hanaki,

Mori

et al. 2024

Plants

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This study confirms for the first time that the significant red coloration of Euglena gracilis is induced by bonito stock (BS), a traditional Japanese food, and intense red light exposure (605~660 nm, 1000~1300 µmol photons/m2/s). Under the condition, excessive photosynthetic activity destroyed many chloroplasts, while carotenoids were maintained, resulting in the formation of reddened cells. The HPLC analysis revealed that diadinoxanthin was the primary carotenoid present in reddened cells. Additionally, an undefined xanthophyll, not produced under normal culture conditions, was synthesized and suggested to contain a C=O bond. While it has been reported that strong light stress can increase the total carotenoid content of cells, this study did not verify this claim, and it should be investigated further in future research. Under white light irradiation conditions (90 μmol photons/m2/s) in BS medium, no reddening of cells was observed, and good growth was achieved (over four times the cell density in CM medium in the seventh incubation). This cell suspension is considered to have a high nutritional value because it is composed of functional food, BS and E. gracilis. The fact that this method does not involve genetic modification suggests the possibility of industrial applications, including food use, even in reddened cells.

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Optical spectroscopic microscopy targeted to oxygenic photosynthetic membranes and organisms

Zhang¹,

Shibata²,

Kumazaki³

2023

Journal of Photochemistry and Photobiology C: Photochemistry Re

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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

Cited by 3 publications

References 25 publications

Noninvasive and safe cell viability assay forEuglena gracilisusing natural food pigment

Noninvasive and safe cell viability assay forEuglena gracilisusing natural food pigment

Reddening of the Unicellular Green Alga Euglena gracilis by Dried Bonito Stock and Intense Red Light Irradiation

Optical spectroscopic microscopy targeted to oxygenic photosynthetic membranes and organisms

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