Effects of enhanced UV-B irradiation on the red coloured freshwater flagellate Euglena sanguinea

Gerber, Sabine

doi:10.1016/0168-6496(94)90011-6

Cited by 7 publications

(8 citation statements)

References 10 publications

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“…Euglena sanguinea is a surface-dwelling freshwater alga colored red by hematochrome, a mixture of carotenoids with an astaxanthin diester as its major component. Hematochrome accumulation is induced by UV-B, suggesting a UV-protective role (55). However, studies with Phycomyces blakesleeanus (56), Neurospora crassa (57) and Halobacterium spp.…”

Section: Uv Optics Of C Nivalis Cellsmentioning

confidence: 99%

Ultraviolet Radiation and the Snow Alga Chlamydomonas nivalis (Bauer) Wille¶

Gorton¹,

Vogelmann²

2003

Photochem Photobiol

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Aplanospores of Chlamydomonas nivalis are frequently found in high-altitude, persistent snowfields where they are photosynthetically active despite cold temperatures and high levels of visible and ultraviolet (UV) radiation. The goals of this work were to characterize the UV environment of the cells in the snow and to investigate the existence and localization of screening compounds that might prevent UV damage. UV irradiance decreased precipitously in snow, with UV radiation of wavelengths 280-315 nm and UV radiation of wavelengths 315-400 nm dropping to 50% of incident levels in the top 1 and 2 cm, respectively. Isolated cell walls exhibited UV absorbance, possibly by sporopollenin, but this absorbance was weak in images of broken or plasmolyzed cells observed through a UV microscope. The cells also contained UV-absorbing cytoplasmic compounds, with the extrachloroplastic carotenoid astaxanthin providing most of the screening. Additional screening compound(s) soluble in aqueous methanol with an absorption maximum at 335 nm played a minor role. Thus, cells are protected against potentially high levels of UV radiation by the snow itself when they live several centimeters beneath the surface, and they rely on cellular screening compounds, chiefly astaxanthin, when located near the surface where UV fluxes are high.

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Section: Uv Optics Of C Nivalis Cellsmentioning

confidence: 99%

Ultraviolet Radiation and the Snow Alga Chlamydomonas nivalis (Bauer) Wille¶

Gorton¹,

Vogelmann²

2003

Photochem Photobiol

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“…Euglena species, light-avoidance movements are absent, and in fact this species only orientates by positive phototaxis (Gerber & Häder, 1994), even at high irradiance. We also show that E. sanguinea was defective in thermal energy dissipation mechanisms (Fig.…”

Section: Discussionmentioning

confidence: 89%

Rapid colour changes inEuglena sanguinea(Euglenophyceae) caused by internal lipid globule migration

Laza‐Martínez

Fernández‐Marín

Garcı́a-Plazaola

2018

European Journal of Phycology

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The accumulation of red pigments, frequently carotenoids, under chronic stress is a response observed in diverse kinds of eukaryotic photoautotrophs. It is thought that red pigments protect the chlorophyll located underneath by a light-shielding mechanism. However, the synthesis or degradation of carotenoids is a slow process and this response is usually only observed when the stress is maintained over long periods of time. In contrast, rapid colour changes have been reported in the euglenophyte Euglena sanguinea. Here we study the ecophysiological process behind this phenomenon through chlorophyll fluorescence, and pigment, colour and ultrastructural analyses. Reddening in E. sanguinea was due to the presence of a large amount of free and esterified astaxanthin (representing 80% of the carotenoid pool). The process was highly dynamic, shifting from green to red in 8 min (and vice-versa in 20 min). This change was not due to de novo carotenogenesis, but to the relocation of cytoplasmic lipid globules where astaxanthin accumulates. Thus, red globules were observed to migrate from the centre of the cell to peripheral locations when exposed to high light. Globule migration seems to be so efficient that other classical mechanisms are not operative in this species. Despite the presence and operation of the diadino-diatoxanthin cycle, non-photochemical quenching was almost undetectable. Since E. sanguinea forms extensive floating colonies, reddening can be observed at a much greater scale than at the cellular level and the mechanism described here is one of the fastest and most dramatic colour changes attributable to photosynthetic organisms at cell and landscape level. In conclusion E. sanguinea shows an extremely dynamic and efficient photoprotective mechanism, based on more on organelle migration than oncarotenoid 3 biosynthesis, which prevents excess light absorption by chlorophylls reducing the need for other protective processes related to energy dissipation.

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“…The fatty acid of the glycoside ester was oleic acid, which was also one of the main fatty acids of the Ax esters in H. pluvialis. Euglena (class Euglenophyta) accumulates also Ax [72]. Although the main product of SC biosynthesis appears to be Ax in Haematococcus, Chlamydomonas and Euglena, there might be different biosynthetic pathways present.…”

Section: Discussionmentioning

confidence: 99%

Time‐ and media‐dependent secondary carotenoid accumulation in Haematococcus pluvialis

Grewe

Griehl

2008

Biotechnology Journal

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The green microalgae Haematococcus pluvialis synthesizes secondary carotenoids after exposure to environmental stress, a process that is used for the biotechnological production of astaxanthin (Ax). This study reports, for the first time, the medium-dependent changes in the carotenoid pattern throughout the cultivation process as well as the exact composition of carotenoids and their fatty acid mono-and diesters using LC-MS. Secondary carotenoid formation started immediately upon exposure to nutrient depletion and high light conditions. Ax and its corresponding monoand diesters were detected simultaneously. After 15 days of cultivation, no significant changes were detected in carotenoid composition; however, the ratio between carotenoid mono-and diesters still varied. Main carotenoids were identified as Ax linolenate and Ax oleate, but also five adonirubin and one lutein monoester were detected. The influence of three different autotroph media was studied on carotenoid content, which reached a maximum 16.1 mg/g dry weight. The results indicate that media composition has an influence on the ratio of Ax mono-to diester but not on the qualitative composition of secondary carotenoids in H. pluvialis. Beside the pathway via echinenone, canthaxanthin and adonirubin the results indicate that Ax biosynthesis takes place via another route: from β-carotene via β-cryptoxanthin, zeaxanthin and adonixanthin.

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Effects of enhanced UV-B irradiation on the red coloured freshwater flagellate Euglena sanguinea

Cited by 7 publications

References 10 publications

Ultraviolet Radiation and the Snow Alga Chlamydomonas nivalis (Bauer) Wille¶

Ultraviolet Radiation and the Snow Alga Chlamydomonas nivalis (Bauer) Wille¶

Rapid colour changes inEuglena sanguinea(Euglenophyceae) caused by internal lipid globule migration

Time‐ and media‐dependent secondary carotenoid accumulation in Haematococcus pluvialis

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