UV tolerance Dotaz Zobrazit nápovědu
We studied the resistance of Parmotrema austrosinense to UV-B stress. We focused on the effects of a high dose UV-B radiation on the content of chlorophylls, carotenoids and UV-B screening compounds. Photosynthetic parameters were measured by chlorophyll fluorescence (potential and effective quantum yields, photochemical and non-photochemical quenching) and evaluated in control and UV-B-treated lichens. Lichens from two different locations in Cordoba, Argentina, were selected: (i) high altitude and dry plots at (Los Gigantes) and (ii) lowland high salinity plots (Salinas Grandes). UV-B treatment led to a decrease in the content of photosynthetic pigments and UV-B screens (absorbance decrease in 220-350 nm) in the samples from Salinas Grandes, while in Los Gigantes samples, an increase in UV-B screen content was observed. Chlorophyll fluorescence parameters showed a UV-B-induced decline in FV /FM , ΦPSII and qP indicating limitation of primary photosynthetic processes in photosystem II (PSII) of symbiotic alga, more pronounced in Salinas Grandes samples. Protective mechanism of PSII were activated by the UV-B treatment to a higher extent in samples from Salinas Grandes (NPQ 0.48) than in Los Gigantes samples (NPQ 0.26). We concluded that site-related characteristics, and in particular different UV-B radiation regimen, had a strong effect on resistance of the photosynthetic apparatus of P. austrosinense to UV-B radiation.
- Klíčová slova
- Absorbance, UV spectra, UV-B resistance, chlorophyll fluorescence parameters, lichens,
- MeSH
- chlorofyl analýza metabolismus MeSH
- ekosystém MeSH
- fluorescence MeSH
- fotosyntéza účinky záření MeSH
- karotenoidy analýza metabolismus MeSH
- lišejníky chemie metabolismus účinky záření MeSH
- nadmořská výška MeSH
- tolerance k soli účinky záření MeSH
- ultrafialové záření * MeSH
- Publikační typ
- časopisecké články MeSH
- Názvy látek
- chlorofyl MeSH
- karotenoidy MeSH
Lichen photobionts in situ have an extremely UV-B tolerant photosystem II efficiency (Fv/Fm). We have quantified the UV-B-screening offered by the mycobiont and the photobiont separately. The foliose lichens Nephroma arcticum and Umbilicaria spodochroa with 1: intact or 2: removed cortices were exposed to 0.7 Wm-2 UV-BBE for 4 h. Intact thalli experienced no reduction in Fv/Fm, whereas cortex removal lowered Fv/Fm in exposed photobiont layers by 22% for U. spodochroa and by 14% for N. arcticum. We also gave this UV-B dose to algal cultures of Coccomyxa and Trebouxia, the photobiont genera of N. arcticum and U. spodochroa, respectively. UV-B caused a 56% reduction in Fv/Fm for Coccomyxa, and as much as 98% in Trebouxia. The fluorescence excitation ratio (FER) technique comparing the fluorescence from UV-B or UV-A-excitation light with blue green excitation light using a Xe-PAM fluorometer showed that these photobiont genera did not screen any UV-B or UV-A The FER technique with a Multiplex fluorometer estimated the UV-A screening of isolated algae to be 13-16%, whereas intact lichens screened 92-95% of the UV-A. In conclusion, the cortex of N. arcticum and U. spodochroa transmitted no UV-B and little UV-A to the photobiont layer beneath. Thereby, the upper lichen cortex forms an efficient fungal solar radiation screen providing a high UV-B tolerance for studied photobionts in situ. By contrast, isolated photobionts have no UV-B screening and thus depend on their fungal partners in nature.
- Klíčová slova
- Chlorophyll fluorescence, Coccomyxa, Lichen cortex, Nephroma arcticum, Trebouxia, UV-screening, Umbilicaria spodochroa,
- MeSH
- fluorometrie MeSH
- fotosystém II (proteinový komplex) metabolismus MeSH
- fyziologická adaptace účinky záření MeSH
- lišejníky mikrobiologie fyziologie účinky záření MeSH
- symbióza MeSH
- ultrafialové záření * MeSH
- Publikační typ
- časopisecké články MeSH
- Názvy látek
- fotosystém II (proteinový komplex) MeSH
Lichen photobionts in situ have an extremely UV-B tolerant photosystem II efficiency (Fv/Fm). We have quantified the UV-B-screening offered by the mycobiont and the photobiont separately. The foliose lichens Nephroma arcticum and Umbilicaria spodochroa with 1: intact or 2: removed cortices were exposed to 0.7 Wm-2 UV-BBE for 4 h. Intact thalli experienced no reduction in Fv/Fm, whereas cortex removal lowered Fv/Fm in exposed photobiont layers by 22% for U. spodochroa and by 14% for N. arcticum. We also gave this UV-B dose to algal cultures of Coccomyxa and Trebouxia, the photobiont genera of N. arcticum and U. spodochroa, respectively. UV-B caused a 56% reduction in Fv/Fm for Coccomyxa, and as much as 98% in Trebouxia. The fluorescence excitation ratio (FER) technique comparing the fluorescence from UV-B or UV-A-excitation light with blue green excitation light using a Xe-PAM fluorometer showed that these photobiont genera did not screen any UV-B or UV-A The FER technique with a Multiplex fluorometer estimated the UV-A screening of isolated algae to be 13-16%, whereas intact lichens screened 92-95% of the UV-A. In conclusion, the cortex of N. arcticum and U. spodochroa transmitted no UV-B and little UV-A to the photobiont layer beneath. Thereby, the upper lichen cortex forms an efficient fungal solar radiation screen providing a high UV-B tolerance for studied photobionts in situ. By contrast, isolated photobionts have no UV-B screening and thus depend on their fungal partners in nature.
- Klíčová slova
- Chlorophyll fluorescence, Coccomyxa, Lichen cortex, Nephroma arcticum, Trebouxia, UV-screening, Umbilicaria spodochroa,
- MeSH
- Ascomycota fyziologie MeSH
- fluorometrie MeSH
- fotosystém II (proteinový komplex) metabolismus MeSH
- fyziologická adaptace účinky záření MeSH
- lišejníky účinky záření MeSH
- symbióza MeSH
- ultrafialové záření * MeSH
- Publikační typ
- časopisecké články MeSH
- Názvy látek
- fotosystém II (proteinový komplex) MeSH
The protection of Escherichia coli bacteria and the yeast Saccharomyces cerevisiae against UV-C radiation by ethanol was studied. It was found that the fraction of surviving cells increases with increasing ethanol concentration. The specific protection depends on the dose rate, concentration range of ethanol, and it is higher for yeast compared to the bacteria.
- MeSH
- buněčná membrána účinky záření MeSH
- buněčná stěna účinky záření MeSH
- Escherichia coli účinky záření MeSH
- ethanol farmakologie MeSH
- Saccharomyces cerevisiae účinky záření MeSH
- tolerance záření * MeSH
- ultrafialové záření * MeSH
- vysoká teplota MeSH
- vztah dávky záření a odpovědi MeSH
- Publikační typ
- časopisecké články MeSH
- Názvy látek
- ethanol MeSH
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.
- Klíčová slova
- Green algae, Metabolomics, UV simulation, UV-A, UV-B, Ultrastructure,
- MeSH
- Chlorophyta metabolismus MeSH
- fotosyntéza fyziologie MeSH
- ultrafialové záření škodlivé účinky MeSH
- Publikační typ
- časopisecké články MeSH
- Geografické názvy
- Antarktida MeSH
- Arktida MeSH
The main objective of this study was to determine the effects of acclimation to ultraviolet (UV) and photosynthetically active radiation (PAR) on photoprotective mechanisms in barley leaves. Barley plants were acclimated for 7 days under three combinations of high or low UV and PAR treatments ([UV-PAR-], [UV-PAR+], [UV+PAR+]). Subsequently, plants were exposed to short-term high radiation stress (HRS; defined by high intensities of PAR - 1000 μmol m(-2) s(-1), UV-A - 10 W m(-2) and UV-B 2 W m(-2) for 4 h), to test their photoprotective capacity. The barley variety sensitive to photooxidative stress (Barke) had low constitutive flavonoid content compared to the resistant variety (Bonus) under low UV and PAR intensities. The accumulation of lutonarin and 3-feruloylquinic acid, but not of saponarin, was greatly enhanced by high PAR and further increased by UV exposure. Acclimation of plants to both high UV and PAR intensities also increased the total pool of xanthophyll-cycle pigments (VAZ). Subsequent exposure to HRS revealed that prior acclimation to UV and PAR was able to ameliorate the negative consequences of HRS on photosynthesis. Both total contents of epidermal flavonols and the total pool of VAZ were closely correlated with small reductions in light-saturated CO2 assimilation rate and maximum quantum yield of photosystem II photochemistry caused by HRS. Based on these results, we conclude that growth under high PAR can substantially increase the photoprotective capacity of barley plants compared with plants grown under low PAR. However, additional UV radiation is necessary to fully induce photoprotective mechanisms in the variety Barke. This study demonstrates that UV-exposure can lead to enhanced photoprotective capacity and can contribute to the induction of tolerance to high radiation stress in barley.
- Klíčová slova
- Barley genotype, Photoinhibition, Photoprotection, Polyphenols, Xanthophylls,
- MeSH
- fotosyntéza účinky záření MeSH
- fyziologický stres účinky záření MeSH
- ječmen (rod) metabolismus MeSH
- listy rostlin metabolismus MeSH
- tolerance záření účinky záření MeSH
- ultrafialové záření * MeSH
- vztah mezi dávkou a účinkem léčiva MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Turfgrasses are monocotyledonous plants from the family Poaceae. They are widely used in green spaces and are considered one of the most economically important horticultural crops in the world. Turfgrass quality is affected by several environmental factors including light, which is involved in the quality decline of transplanted sod. Ultraviolet-B (UV-B) is an important regulator of plant growth and development. Plants growing and/or stored in protected systems, such as in sod production, may be more vulnerable to UV-B damage than those growing in the field due to acclimation. Few studies on the effects of UV-B on turfgrass physiology have been published. Therefore, the aim of this study was to evaluate the influence of UV-B irradiation on the photosynthetic performance of five cool-season turfgrasses, namely Agrostis stolonifera L., Festuca arundinacea Schreb., Poa supina Schrad., Poa pratensis L. and Lolium perenne L. Turfgrasses were exposed to 18.25 kJ m-2 d-1 biologically effective UV-B in growth chambers under controlled conditions. Measurements included photosynthetic pigments, chlorophyll fluorescence and gas exchanges monitored for 16 d-UV-B treatment and after recovery. Content of pigments decreased with UV-B exposure with significant differences among the species. UV-B also affected the photosystem II (PSII) efficiency depending on the exposure period and species. Similarly, gas exchange parameters showed different effects among species after UV-B exposure compromising the assimilation of CO2. Multivariate analysis highlighted three main clusters of species confirming their different UV-B tolerance and ability to restore PSII photochemistry after recovery, from which Festuca arundinacea resulted to be the most tolerant.
- Klíčová slova
- Chlorophyll fluorescence, Gramineae, Leaf gas exchange, Photosynthetic pigments, Ultraviolet-B,
- MeSH
- Agrostis fyziologie MeSH
- chlorofyl MeSH
- Festuca fyziologie MeSH
- fotosyntéza * MeSH
- fotosystém II (proteinový komplex) MeSH
- jílek fyziologie MeSH
- Poa fyziologie MeSH
- ultrafialové záření * MeSH
- Publikační typ
- časopisecké články MeSH
- Názvy látek
- chlorofyl MeSH
- fotosystém II (proteinový komplex) MeSH
We investigated the effect of leaf ontogeny and barley genotype on the accumulation of phenolic compounds (PhCs) induced by ultraviolet (UV) and photosynthetically active radiation (PAR). We hypothesized that different groups of PhCs are induced in leaves differing in ontogeny, and that this has consequences for protective functions and the need for other protection mechanisms. Generally, lower constitutive contents of PhCs (under conditions of UV exclusion and reduced PAR) were found in a UV-sensitive genotype (Barke) compared to a tolerant genotype (Bonus). However, UV and PAR induced accumulation of PhCs exceeded the constitutive amounts several fold. Specifically, lutonarin, 3-feruloylquinic acid, unidentified hydroxycinnamic acid and luteolin derivatives were markedly enhanced by high PAR and UV irradiances. Leaves developed during UV and PAR treatments had higher PhCs contents than mature leaves already fully developed at the onset of the UV and PAR treatment. UV and PAR treatments had, however, a minor effect on saponarin and unidentified apigenin derivatives which occur particularly in mature leaves of the tolerant genotype Bonus. In addition, high UV and PAR intensities increased the total content of xanthophylls (VAZ), while chlorophyll content was reduced, particularly in developing leaves. A redundancy analysis revealed positive associations between most of PhCs and VAZ and a negative association between total chlorophylls and carotenoids. Non-linear relationships between VAZ and lutonarin and other PhCs indicate that VAZ accumulation can compensate for the insufficient efficiency of anti-oxidative protection mediated by PhCs. Accordingly, we conclude that UV and PAR-induced accumulation of PhCs is affected by leaf ontogeny, however, this effect is compound-specific.
- Klíčová slova
- Hordeum vulgare, Leaf age, Light irradiance, Photoprotection, Secondary metabolites, Ultraviolet radiation, Xanthophyll cycle,
- MeSH
- chlorofyl metabolismus MeSH
- fenoly metabolismus MeSH
- flavonoly metabolismus MeSH
- genotyp MeSH
- ječmen (rod) genetika účinky záření MeSH
- karotenoidy metabolismus MeSH
- listy rostlin metabolismus účinky záření MeSH
- ultrafialové záření * MeSH
- xanthofyly metabolismus MeSH
- Publikační typ
- časopisecké články MeSH
- Názvy látek
- chlorofyl MeSH
- fenoly MeSH
- flavonoly MeSH
- karotenoidy MeSH
- xanthofyly MeSH
Effects of ultraviolet radiation (UV) on the human skin are summarized in the introductory part from physical and biological point of view, especially photoaging and photocarcinogenesis. Special attention has been paid to skin phototype which characterizes the individual susceptibility to UV. The minimal erythema dose (MED) serves for establishment of this susceptibility. The mean MEDs for white population in other countries are also shown here. Mechanisms of natural photoprotection in connection with instructions how to increase artificial photoprotection are described here. The investigation of skin type incidence in our population and determining their mean MEDs for UV-B and polychromatic light was the aim of practical work. The UV-B MED is in average 23.4 mJ/cm2. The further work has been concentrated on the assessment of pigmentation response after irradiation and especially on the comparison of the minimal erythema doses before season and after it. We found mean double increase of the MED after sunlight exposition during summer season. We suggested, that double increasing of seasonal natural photoprotection does not represent definitive protection for most people and does not impair summer warning system in media which is based on winter MEDs. Some recommendations for improvement of protection of Czech population against UV radiation are proposed in conclusion.
- MeSH
- dávka záření MeSH
- dítě MeSH
- dospělí MeSH
- erytém etiologie MeSH
- kůže účinky záření MeSH
- lidé středního věku MeSH
- lidé MeSH
- mladiství MeSH
- předškolní dítě MeSH
- senioři nad 80 let MeSH
- senioři MeSH
- tolerance záření * MeSH
- ultrafialové záření škodlivé účinky MeSH
- Check Tag
- dítě MeSH
- dospělí MeSH
- lidé středního věku MeSH
- lidé MeSH
- mladiství MeSH
- mužské pohlaví MeSH
- předškolní dítě MeSH
- senioři nad 80 let MeSH
- senioři MeSH
- ženské pohlaví MeSH
- Publikační typ
- anglický abstrakt MeSH
- časopisecké články MeSH
- Geografické názvy
- Česká republika MeSH
Vegetative cells in dried, mucilagenous mass of Gloeocapsa aeruginosa and Aphanothece nidulans, reticulum of Hydrodictyon reticulatum, mucilagenous mass of Chroococcus minor, and filaments of Oedogonium sp. and Scytonema hofmanni died within 1/2, 1/2, 1/2, 1, 3 and 6 h, respectively, while dried vegetative filaments of Phormidium foveolarum retained under similar storage conditions viability for 4 d. P. foveolarum tolerated 1 mol/L NaCl. The resistance to desiccation in P. foveolarum exhibited similar dependence as that to heat or UV light. The water stress imposed on growing algae either on high-agar solid media or in NaCl-containing liquid media reduced at various levels or altogether inhibited the survival of vegetative parts in all, the cell division in C. minor, G. aeruginosa and A. nidulans, formation of heterocyst and false branch in S. hofmanni, oogonium in Oedogonium sp., and daughter net in H. reticulatum. Heat or UV shock of any level also produced similar effects as that by water stress. P. foveolarum tolerated low light level of 10 and 2 mumol m-2 s-1 and no light longer than the rest of other algae studied. Tolerance of microalgal forms to water, heat or UV stress depends primarily upon cell-wall characteristics or cell-sap osmotic properties rather than their habitats, morphology and prokaryotic or eukaryotic nature.
