UV-B radiation and selenium affected energy availability in green alga Zygnema

Germ, Mateja; Kreft, Ivan; Gaberščik, Alenka

doi:10.2478/s11756-009-0062-2

Cited by 14 publications

(13 citation statements)

References 28 publications

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“…Increased ETS activity in hybrid buckwheat by the addition of Se is in line with fi ndings that the addition of Se to Vigna radiata enhanced respiratory as well as succinate dehydrogenase activity and the involvement of Se in mitochondrial membrane functions (Easwari and Lalitha 1995). Germ et al (2009) also observed that Se is involved in activation of energy resources in green alga Zygnema sp.…”

Section: Plant Partsupporting

confidence: 83%

Selenium uptake and Se compounds in Se-treated buckwheat

Golob¹,

Germ²,

Kreft³

et al. 2016

Acta Botanica Croatica

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-In fi eld experiments, tartary buckwheat and hybrid buckwheat were foliarly sprayed with an aqueous solution of sodium selenate (20 mg Se L -1 ). In treated plants, the selenium content was signifi cantly higher than in controls, irrespective of the plant part and taxon of buckwheat. The highest average Se concentrations in hybrid and tartary buckwheat were found in seeds. The main Se species found in seeds was Semethionine. Selenium-sprayed plants had higher photochemical effi ciency of photosystem II in both taxa and higher electron transport system activity in hybrid buckwheat, suggesting a positive effect of Se on physiological characteristics. Because of the concentration of Se in both buckwheat taxa and selenomethionine as the dominant species of Se, Se-enriched buckwheat is a potential source of dietary Se for animals and humans.

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Section: Plant Partsupporting

confidence: 83%

Selenium uptake and Se compounds in Se-treated buckwheat

Golob¹,

Germ²,

Kreft³

et al. 2016

Acta Botanica Croatica

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“…Folin–Ciocalteu) were used for a more imprecise determination [e.g. 18, 20, 41]. The presence of such phenolics, which are not common in freshwater microalgae, supports the hypothesis that their production might be crucial in UV protection of Zygnema .…”

Section: Discussionmentioning

confidence: 99%

“…Even in polar regions, Zygnema is quite common and easy to recognise due to its mat-forming growth [25, 31, 40]. As mentioned, no harmful effect of experimental UV exposure on Zygnema was observed in previous studies [20, 31], yet, the nature of UV protection in Zygnema remains unknown. We expect that the alga obtains UV resistance by the accumulation of phenolic compounds, which can be analysed by high-performance liquid chromatography (HPLC).…”

Section: Introductionmentioning

confidence: 99%

Changes in Phenolic Compounds and Cellular Ultrastructure of Arctic and Antarctic Strains of Zygnema (Zygnematophyceae, Streptophyta) after Exposure to Experimentally Enhanced UV to PAR Ratio

et al. 2012

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Ultraviolet (UV) radiation has become an important stress factor in polar regions due to anthropogenically induced ozone depletion. Although extensive research has been conducted on adaptations of polar organisms to this stress factor, few studies have focused on semi-terrestrial algae so far, in spite of their apparent vulnerability. This study investigates the effect of UV on two semi-terrestrial arctic strains (B, G) and one Antarctic strain (E) of the green alga Zygnema, isolated from Arctic and Antarctic habitats. Isolates of Zygnema were exposed to experimentally enhanced UV A and B (predominant UV A) to photosynthetic active radiation (PAR) ratio. The pigment content, photosynthetic performance and ultrastructure were studied by means of high-performance liquid chromatography (HPLC), chlorophyll a fluorescence and transmission electron microscopy (TEM). In addition, phylogenetic relationships of the investigated strains were characterised using rbcL sequences, which determined that the Antarctic isolate (E) and one of the Arctic isolates (B) were closely related, while G is a distinct lineage. The production of protective phenolic compounds was confirmed in all of the tested strains by HPLC analysis for both controls and UV-exposed samples. Moreover, in strain E, the content of phenolics increased significantly (p = 0.001) after UV treatment. Simultaneously, the maximum quantum yield of photosystem II photochemistry significantly decreased in UV-exposed strains E and G (p < 0.001), showing a clear stress response. The phenolics were most probably stored at the cell periphery in vacuoles and cytoplasmic bodies that appear as electron-dense particles when observed by TEM after high-pressure freeze fixation. While two strains reacted moderately on UV exposure in their ultrastructure, in strain G, damage was found in chloroplasts and mitochondria. Plastidal pigments and xanthophyll cycle pigments were investigated by HPLC analysis; UV A- and UV B-exposed samples had a higher deepoxidation state as controls, particularly evident in strain B. The results indicate that phenolics are involved in UV protection of Zygnema and also revealed different responses to UV stress across the three strains, suggesting that other protection mechanisms may be involved in these organisms.

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“…Several studies have investigated the effects of UV radiation on Zygnematophycean green algae (e.g., Meindl and Lütz 1996; Lütz et al 1997; Holzinger et al 2009; Germ et al 2009; Pichrtová et al 2013; Stamenković and Hanelt 2014; Prieto-Amador 2016; Stamenković and Hanelt 2017). Pichrtová et al (2013) investigated the changes in phenolic compounds in three species of Zygnema from either Arctic or Antarctic habitats.…”

Section: Introductionmentioning

confidence: 99%

Arctic, Antarctic, and temperate green algae Zygnema spp. under UV-B stress: vegetative cells perform better than pre-akinetes

et al. 2018

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Species of Zygnema form macroscopically visible mats in polar and temperate terrestrial habitats, where they are exposed to environmental stresses. Three previously characterized isolates (Arctic Zygnema sp. B, Antarctic Zygnema sp. C, and temperate Zygnema sp. S) were tested for their tolerance to experimental UV radiation. Samples of young vegetative cells (1 month old) and pre-akinetes (6 months old) were exposed to photosynthetically active radiation (PAR, 400–700 nm, 400 μmol photons m−2 s−1) in combination with experimental UV-A (315–400 nm, 5.7 W m−2, no UV-B), designated as PA, or UV-A (10.1 W m−2) + UV-B (280–315 nm, 1.0 W m−2), designated as PAB. The experimental period lasted for 74 h; the radiation period was 16 h PAR/UV-A per day, or with additional UV-B for 14 h per day. The effective quantum yield, generally lower in pre-akinetes, was mostly reduced during the UV treatment, and recovery was significantly higher in young vegetative cells vs. pre-akinetes during the experiment. Analysis of the deepoxidation state of the xanthophyll-cycle pigments revealed a statistically significant (p < 0.05) increase in Zygnema spp. C and S. The content of UV-absorbing phenolic compounds was significantly higher (p < 0.05) in young vegetative cells compared to pre-akinetes. In young vegetative Zygnema sp. S, these phenolic compounds significantly increased (p < 0.05) upon PA and PAB. Transmission electron microscopy showed an intact ultrastructure with massive starch accumulations at the pyrenoids under PA and PAB. A possible increase in electron-dense bodies in PAB-treated cells and the occurrence of cubic membranes in the chloroplasts are likely protection strategies. Metabolite profiling by non-targeted RP-UHPLC-qToF-MS allowed a clear separation of the strains, but could not detect changes due to the PA and PAB treatments. Six hundred seventeen distinct molecular masses were detected, of which around 200 could be annotated from databases. These results indicate that young vegetative cells can adapt better to the experimental UV-B stress than pre-akinetes.Electronic supplementary materialThe online version of this article (10.1007/s00709-018-1225-1) contains supplementary material, which is available to authorized users.

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UV-B radiation and selenium affected energy availability in green alga Zygnema

Cited by 14 publications

References 28 publications

Selenium uptake and Se compounds in Se-treated buckwheat

Selenium uptake and Se compounds in Se-treated buckwheat

Changes in Phenolic Compounds and Cellular Ultrastructure of Arctic and Antarctic Strains of Zygnema (Zygnematophyceae, Streptophyta) after Exposure to Experimentally Enhanced UV to PAR Ratio

Arctic, Antarctic, and temperate green algae Zygnema spp. under UV-B stress: vegetative cells perform better than pre-akinetes

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