Martin Bačkor

Pavol Jozef Šafárik University in Košice, Kassa, Košický, Slovakia

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Publications (70)167.31 Total impact

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    ABSTRACT: Secondary metabolites of lichens can be involved in production of chelates with heavy metals. We hypothesized that parietin plays important role in protection of photobiont cells in Xanthoria parietina from an excess of cadmium ions. Two types of X. parietina lichen thalli, natural with presence of secondary metabolite parietin (p+) as well as without parietin (p−) were exposed to different doses of cadmium (up to 300 μmol g−1 dw). Based on determination of the total and intracellular Cd-accumulation, ergosterol and thiobarbituric acid reactive substances (TBARS) content did not show statistically significant differences in the response of both types of thalli (p+ and p−). However, a stronger toxic effect of the highest Cd-dose on photosynthetic pigment content and chlorophyll a fluorescence was observed in the parietin-depleted thalli. The protective role of parietin against Cd excess was better supported and concluded from the differences observed in the production of non-protein thiol compounds (cysteine, glutathione and phytochelatins) involved in Cd detoxification. In the p+ thalli Cys content was stable but GSH content slightly decreased in the studied Cd range, while in the p− thalli these compounds were completely absent at high Cd doses. At Cd doses higher than 37.5 μmol Cd g−1 dw, toxic to both types of X. parietina thalli, Cys and GSH contents were significantly higher in p+ than in p− thalli. Also, the photobiont partner in the p+ thalli was better protected of the metal exposition, and able to produce phytochelatins (PCs) over the whole range of metal, while in the p− thalli the production was completely inhibited at 75 μmol Cd g−1 dw and higher concentrations, together with the inhibition of cysteine (Cys) and reduced glutathione (GSH) production. The obtained results indicate that the parietin layer is a natural barrier decreasing Cd access to algal cells in X. parietina. Comparison of PCs production appeared to be the most sensitive marker for estimation of Cd availability to photobiont in the symbiotic system.
    Ecological Indicators 11/2015; 58. DOI:10.1016/j.ecolind.2015.05.055 · 3.44 Impact Factor
  • M. Bačkorová · I. Biľová · T. Kimáková · M. Bačkor ·
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    ABSTRACT: Cladina arbuscula subsp. mitis grows on the surfaces of historical Cu-mine spoil heaps rich in Cu, as well as on the surfaces of substrata that are not metal contaminated. This lichen contains the extracellular secondary metabolite, usnic acid (UA), which was previously found to form complexes with metal cations, including Cu. As UA can be experimentally removed from dry lichen thalli using acetone and without the loss of lichen viability, this study attempted to evaluate its role in long-term (8 wks) Cu tolerance in C. arbuscula subsp. mitis. Removal of UA by acetone did not affect the viability of the lichen, however it caused lower intracellular Cu accumulation after 8 wks of experiment at the highest 500 μM Cu doses tested. Thus far, we did not observe de novo synthesis of UA in the UA − variant of the study during the 8 wks of the experiment. Based on the measurements of the selected metabolic processes in the lichen (chlorophyll a fluorescence, chlorophyll a integrity, TBARS production, content of ergosterol and content of soluble proteins) it would seem that presence of UA in C. arbuscula subsp. mitis did not protect this lichen against Cu excess.
    South African Journal of Botany 09/2015; 100:94-100. DOI:10.1016/j.sajb.2015.05.015 · 0.98 Impact Factor
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    ABSTRACT: Lichens are sensitive to the presence of ammonia (NH3) in the environment. However, in order to use them as reliable indicators in biomonitoring studies, it is necessary to establish unequivocally the occurrence of certain symptoms following the exposure to NH3 in the environment. In this paper, we simulated an episode of acute air pollution due to the release of NH3. The biological effects of acute air pollution by atmospheric NH3 have been investigated using N-sensitive (Flavoparmelia caperata) and N-tolerant (Xanthoria parietina) species. Lichen samples were exposed to ecologically relevant NH3 concentrations for 8 weeks, simulating three areas of impact: a control area (2μg/m(3)), an area of intermediate impact (2-35μg/m(3)) and an area of high impact (10-315μg/m(3)), with a peak of pollution reached between the fourth and fifth week. Ammonia affected both the photobiont and the mycobiont in F. caperata, while in X. parietina only the photosynthetic performance of the photobiont was altered after exposure to the highest concentration. In the photobiont of F. caperata we recorded chlorophyll degradation as indicated by OD435/415 ratio, decrease of the photosynthetic performance (as reflected by the maximum quantum yield of primary photochemistry FV/FM and the performance index PIABS); in the mycobiont, ergosterol reduction, membrane lipid peroxidation (as reflected by the increase of thiobarbituric acid reactive substances), alteration (decrease) of the secondary metabolite usnic acid. No effects were detected on caperatic acid and dehydrogenase activity. In X. parietina, the only signal determined by NH3 was the alteration of FV/FM and the performance index PIABS. The results suggest that physiological parameters in N-sensitive lichens well reflect the effects of NH3 exposure and can be applied as early indicators in monitoring studies. Copyright © 2015 Elsevier Inc. All rights reserved.
    Ecotoxicology and Environmental Safety 08/2015; 122:377-383. DOI:10.1016/j.ecoenv.2015.08.025 · 2.76 Impact Factor
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    ABSTRACT: This study investigated if treatment of the lichen Xanthoria parietina (L.) Th. Fr. with glyphosate caused uptake of this herbicide as well as physiological alterations. Samples were treated with Glifene SL®, a common commercial glyphosate-based herbicide, at the lowest recommended doses (3.6g/L) as well as with doses slightly higher than the highest suggested (36g/L). The results clearly showed glyphosate uptake in X. parietina proportionally to the dose provided. Adverse physiological effects were evident on the photosynthetic apparatus (photosynthetic efficiency, chlorophyll a content, chlorophyll degradation) as well as on the fungal respiration rates and cell membrane integrity (ergosterol content, dehydrogenase activity) already after 24h from treatment, also at the low application dose. It is concluded that lichens are suitable organisms for monitoring unwanted biological effects from the application of glyphosate-based herbicides, as well as for detecting the accumulation of this compound in the biota, thus screening for its environmental fate. Copyright © 2015 Elsevier Inc. All rights reserved.
    Ecotoxicology and Environmental Safety 08/2015; 122:193-197. DOI:10.1016/j.ecoenv.2015.07.030 · 2.76 Impact Factor
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    ABSTRACT: Lichens absorb water, gases, dissolved substances , and especially pollutants by the entire surface, and they are considered to be the indicators of air quality. In our experiment, a sensitivity of Cladonia arbuscula subsp. mitis and Cladonia furcata lichens with the same photobiont Trebouxia was tested to nitrogen excess through a sensitivity of both the photobiont and mycobiont. Lichen ecophysiological parameters like chlorophyll a fluorescence, chlorophyll a integrity, the content of photosynthetic pigments, ergosterol, soluble proteins, thiobarbituric acid reactive substances, and secondary compounds were measured during two experiments that differed in time of nitrogen exposure. In the short-term experiment, also higher nitrogen concentrations were used to evaluate the dependence of different nitrogen concentrations. In the short-term experiment , lichens were soaked at the different solutions of ammonium nitrate (NH 4 NO 3) for describing an immediate effect of range of NH 4 NO 3 concentrations. In the long-term experiment, lichens were sprayed with low NH 4 NO 3 concentrations for 3 months for evaluating the effect of naturally occurring low nitrogen concentrations. Results showed that lichens responded differently in spite of having the same photobiont. The mycobiont of C. arbuscula subsp. mitis was more sensitive than mycobiont of C. furcata. In higher nitrogen concentrations, the photobiont of C. furcata was more sensitive than C. arbuscula subsp. mitis photobiont. Both lichens exhibited signs of damage; therefore, we conclude that they are sensitive to nitrogen excess, while C. arbuscula subsp. mitis is more sensitive species. The secondary compound content did not change in neither of lichen species. Cladonia sp. response to nitrogen excess depends on length and nitrogen dose exposure.
    Water Air and Soil Pollution 08/2015; 226(243). DOI:10.1007/s11270-015-2512-5 · 1.55 Impact Factor
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    ABSTRACT: Epiphytic lichens have been used as indicators of environmental quality around a municipal solid waste landfill in C Italy. An integrated approach, using the diversity of epiphytic lichens, as well as element bioaccumulation and physiological parameters in the lichen Flavoparmelia caperata (L.) Hale was applied along a transect from the facility. The results highlighted the biological effects of air pollution around the landfill. The Index of Lichen Diversity (ILD) increased and the content of heavy metals (Cr, Cd, Cu, Fe, Ni and Zn) decreased with distance from the landfill. Clear stress signals were observed in lichens growing in front of the facility, i.e. discoloration, necrosis, membrane lipid peroxidation, lower ergosterol content, higher dehydrogenase activity. Decreased photosynthetic efficiency, altered chlorophyll integrity and production of secondary metabolites were also found. The results suggested that lichens can be profitably used as bioindicators of environmental quality around landfills. Copyright © 2015 Elsevier Ltd. All rights reserved.
    Waste Management 05/2015; 42. DOI:10.1016/j.wasman.2015.04.033 · 3.22 Impact Factor
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    ABSTRACT: Accumulation of heavy metals due to pollution of the environment, particularly in agricultural ecosystems, can cause serious deterioration of crop yield and quality. In this study, we assessed the effect of silicon on physiological, photosynthetic and stress-related aspects of cadmium toxicity in hydroponically grown maize plants (Zea mays L., hybrid Valentina). One concentration of silicon (5 mM) and two concentrations of cadmium (5 and 50 M) added to the cultivation medium were tested. Cadmium alone led to a significant growth inhibition and negatively affected the content of total chlorophylls and the efficiency of photosystem II. Especially in roots, application of cadmium resulted in the accumulation of reactive oxygen species and consequent membrane lipid peroxidation. The supplementation of silicon successfully ameliorated the toxic effect of cadmium on maize plants and enhanced growth, some of the photosynthetic parameters and reduced the level of oxidative stress. In plants exposed to higher concentrations of cadmium silicon also reduced its accumulation, especially in roots. Changes in the accumulation of phenolic compounds may indicate the influence of silicon on this aspect of secondary plant metabolism and its importance in the detoxification of heavy metals.
    Water Air and Soil Pollution 08/2014; 225(8). DOI:10.1007/s11270-014-2056-0 · 1.55 Impact Factor
  • V. Lokajová · M. Bačkorová · M. Bačkor ·
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    ABSTRACT: In the present work, the phytotoxic effects of secondary metabolites extracted from five lichen species (Cladonia arbuscula var. mitis, Cladonia furcata, Hypogymnia physodes, Evernia prunastri and Ramalina farinacea) on cultures of the aposymbiotically grown lichen photobiont Trebouxia erici were evaluated. Toxicity of single secondary metabolites, as well as their naturally occurred mixtures in the lichens was tested at the two selected doses, 0.1 mg/disk and 0.01 mg/disk. Application of all tested metabolites decreased the growth of photobiont cells in a dose dependent manner. However, based on selected physiological parameters, e.g. composition of assimilation pigments, fluorescence of chlorophyll a, content of soluble proteins, production of TBARS and ROS, differential phytotoxicity of tested compounds and their mixtures was confirmed. It appears that most of the secondary metabolites tested in the present study may be functioning as allelochemicals which are controlling the cell division of the algal partner inside the thallus. The allelochemicals may play a key role in maintaining the balance between the symbionts forming the lichen thallus.
    South African Journal of Botany 07/2014; 93:86–91. DOI:10.1016/j.sajb.2014.03.015 · 0.98 Impact Factor
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    ABSTRACT: Enhanced UV-B irradiation is one of the most important abiotic stresses that can influence various aspects of plant morphology, biochemistry and physiology. Silicon as a beneficial element can increase the plant’s tolerance against different abiotic stresses, including UV-B stress. In this work, the effect of silicon supplementation on the sensitivity of young maize (Zea mays L.) seedlings exposed to short-term UV-B radiation was studied. The seedlings were grown with 0 or 5 mM silicon in cultivation medium and on the fifth day of cultivation, they were exposed for 15 and 30 min to UV-B (302 nm) radiation. No significant changes in growth and content of assimilation pigments and the chlorophyll a/b ratio were observed in any of tested irradiation periods in control or Si-treated plants. Under UV-B stress, the content of ROS (hydrogen peroxide and superoxide radical) and TBARS increased in control plants. The oxidative status of Si-treated plants was only slightly affected even after 30 min. Phenolic metabolites (total phenols and flavonoids), important for their screening function under radiation stress, slightly increased after UV-B exposure in control plants, however, only flavonoids increased after 30 min in Si-treated plants. The measured parameters indicated that to some extent silicon supplementation contributes to higher UV-B tolerance of maize seedlings.
    Biologia 01/2014; 69(10). DOI:10.2478/s11756-014-0432-2 · 0.83 Impact Factor
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    ABSTRACT: A series of lichen secondary metabolites (parietin, atranorin, usnic and gyrophoric acid) and their interactions with calf thymus DNA were investigated using molecular biophysics and biochemical methods. The binding constants K were estimated to range from 4.3 × 10(5) to 2.4 × 10(7) M(-1) and the percentage of hypochromism was found to be 16-34% (from spectral titration). The results of spectral measurement indicate that the compounds act as effective DNA-interacting agents. Electrophoretic separation studies prove that from all the metabolites tested in this study, only gyrophoric acid exhibited an inhibitory effect on Topo I (25 μM).
    Toxicology in Vitro 11/2013; 28(2). DOI:10.1016/j.tiv.2013.11.003 · 2.90 Impact Factor
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    ABSTRACT: Effect of nitric oxide donor (sodium nitroprusside, SNP, 500 μM) or hydrogen peroxide scavenger (dithiothreitol, DTT, 500 μM) on cadmium (Cd) or copper (Cu) uptake (150 μM solutions) and toxicity using Scenedesmus quadricauda was studied. Combined treatments (Cd or Cu + DTT or SNP) usually ameliorated metal-induced toxicity at the level of pigments, proteins, and mineral nutrients in comparison with respective metal alone. Viability tests (MTT and TTC) showed the lowest values preferentially in Cu treatments, indicating higher toxicity in comparison with Cd. Cd showed low impact on amino acids while strong Cu-induced depletion was mitigated by DTT and SNP. Amount of ROS and NO showed the most pronounced responses in SNP variants being rather reciprocal than parallel and regulated ascorbate peroxidase activity. Blot gel analyses of hsp70 protein did not reveal extensive changes after given exposure period. Phenols were elevated by DTT alone while all Cu treatments revealed depletion. Total Cu content decreased while total Cd content increased in metal + SNP or metal + DTT. Subsequent experiment using lower Cd, SNP or DTT doses (10 and 100 μM) revealed concentration-dependent impact on Cd uptake. Overall, DTT was found to be more suitable for the amelioration of metal-induced toxicity.
    Environmental Science and Pollution Research 02/2013; 20(8). DOI:10.1007/s11356-013-1541-0 · 2.83 Impact Factor
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    ABSTRACT: a b s t r a c t The vibrational characterization of the anthraquinone pigment and drug parietin was carried out by means of infrared spectroscopy, Raman and Surface-enhanced Raman scattering (SERS) at different laser excitation lines. The vibrational spectra obtained experimentally were analysed using DFT calculations at the B3LYP/6-31+G** level. The SERS technique was very useful in the vibrational study of parietin, and was proven to be a highly sensitive technique for the detection of low concentrations of the drug. The silver nanoparticles used as SERS substrates were prepared by reduction with hydroxylamine hydrochloride. The adsorption of parietin on the nanoparticles at different surface coverage leaded to the calculation the limit of detection (LOD) and the adsorption constant (K ad) of parietin on the SERS substrate.
    Vibrational Spectroscopy 11/2012; 63:477-484. DOI:10.1016/j.vibspec.2012.09.015 · 2.00 Impact Factor
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    ABSTRACT: Lichens are a known source of approximately 800 unique secondary metabolites, many of which play important ecological roles, including regulating the equilibrium between symbionts. However, only a few of these compounds have been assessed for their effectiveness against various in vitro cancer models. Moreover, the mechanisms of biological activity of lichen secondary metabolites on living cells (including cancer cells) are still almost entirely unknown. In the present study, we investigated the mechanisms of cytotoxicity of four lichen secondary metabolites (parietin, atranorin, usnic acid and gyrophoric acid) on A2780 and HT-29 cancer cell lines. We found that usnic acid and atranorin were more effective anti-cancer compounds when compared to parietin and gyrophoric acid. Usnic acid and atranorin were capable of inducing a massive loss in the mitochondrial membrane potential, along with caspase-3 activation (only in HT-29 cells) and phosphatidylserine externalization in both tested cell lines. Induction of both ROS and especially RNS may be responsible, at least in part, for the cytotoxic effects of the tested compounds. Based on the detection of protein expression (PARP, p53, Bcl-2/Bcl-xL, Bax, p38, pp38) we found that usnic acid and atranorin are activators of programmed cell death in A2780 and HT-29, probably through the mitochondrial pathway.
    Toxicology in Vitro 04/2012; 26(3):462-8. DOI:10.1016/j.tiv.2012.01.017 · 2.90 Impact Factor
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    ABSTRACT: The lichen Evernia prunastri is very frequently employed in lichen biomonitoring studies and its sensitivity to air pollution has been confirmed at the community level many times. However, studies focused on the physiological responses of this lichen to pollutants are underrepresented. The degree of total as well as intracellular Cu uptake by the lichen after 4 and 24 h prolonged exposure was compared with selected physiological markers including levels of assimilation pigments, chlorophyll a fluorescence, ergosterol, soluble proteins, hydrogen peroxide, superoxide, amino acids, reducing sugars and total soluble phenols. Although the degree of total as well as intracellular Cu uptake by the lichen after 4 and 24 h prolonged exposure were comparable, metabolic responses after 4 and 24 h were very different. Carotenoids, ergosterol and soluble proteins decreased due to Cu exposure and these processes were followed with an increase of superoxide content. Excess of Cu in thalli of E. prunastri after 24 h was toxic and altered almost all tested parameters, including depletion of reducing sugars. We did not observe stimulation of free amino acid synthesis in Cu treated lichen, in fact the content of many particular amino acids decreased. Content of total soluble phenols was unaltered by Cu excess.
    Plant Growth Regulation 01/2012; 69(1). DOI:10.1007/s10725-012-9741-z · 1.67 Impact Factor
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    ABSTRACT: Effect of methyl jasmonate (MeJA) in the concentrations of 10 or 100 μM on selected physiological parameters in Scenedesmus quadricauda (Turp.) Bréb. after 24 h of exposure was studied. Results were compared with the application of general toxic metal (cadmium, Cd) to identify MeJA-specific responses. Accumulation of reactive oxygen species (ROS; hydrogen peroxide and superoxide) was the most elevated by 10 μM MeJA and 100 μM Cd, while total chls showed decrease (Cd) and increase (MeJA) in these variants. The amount of carotenoids and cell viability were affected neither by MeJA nor by Cd application. The sum of free amino acids was considerably elevated by 10 μM Cd (increase in histidine, threonine, arginine, leucine, and lysine mainly) but depleted by 100 μM MeJA (14 from 17 compounds decreased), while accumulation of soluble proteins was unaffected by Cd and enhanced by MeJA. Cadmium application reduced the amount of Ca and also Mg in the case of 100 μM Cd, while MeJA had no effect on the content of mineral nutrients. Total Cd content reached 557 and 1,334 μg · g−1 dry weight (dwt) in 10 and 100 μM Cd variant, respectively. Intracellular Cd uptake was ca. 55% from total Cd content in both Cd variants. The present findings are discussed in the context of the available literature, and possible explanations are suggested.
    Journal of Phycology 10/2011; 47(5). DOI:10.1111/j.1529-8817.2011.01027.x · 2.84 Impact Factor
  • B. Pawlik-Skowrońska · M. Bačkor ·
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    ABSTRACT: Many lichens can cope with heavy-metal stress, however, the mechanisms of lichen tolerance are still not fully understood. Some lichen secondary metabolites (depsides and depsidones), produced in lichens by the fungal symbiont and accumulated on the outer surface of its hyphae, are supposed to play an important role in the extracellular immoblilization of heavy metals. Lichen photobionts (algal partners in the symbiosis), although surrounded by the mycobiont hyphae, may also accumulate high amounts of trace metals. This can lead to physiological disruptions and morphological damage in algal cells and hence affect the lichen physiological status. We hypothesized that lichen species/specimens living in heavily polluted sites and showing HM tolerance possess a higher content of secondary metabolites than those living in unpolluted sites. Hence, their photobionts can be better protected from the excess of metal ions and need to produce less metal-complexing phytochelatins (PCn) to combat metal toxicity. Specimens of Hypocenomyce scalaris, Cladonia furcata and Lepraria spp. sampled from Zn/Pb-polluted and control sites were compared for the accumulation of Zn/Pb and secondary metabolites, as well as for their production of phytochelatins and glutathione in response to experimental Zn or Pb exposure. Generally, the lichen specimens sampled from the HM-polluted site contained higher amounts of Zn and Pb as well as lichen substances (different depsides and depsidones) than those from the control site. A strong positive correlation was found between the accumulation of secondary metabolites and Zn/Pb accumulation (R2 = 0.98 and 0.63, respectively). For the first time, production of phytochelatins (PC2–3) in response to Zn and Pb (50–200 μM) exposure was found in H. scalaris, L. elobata, L. incana and C. furcata. In both species of Lepraria also cysteine, a substrate for GSH and PCs synthesis was detected. The lichens from the polluted site produced under the same exposure conditions, or in response to higher metal concentrations, lower amounts of PCn than those sampled from the control site. It strongly suggests that less Zn and Pb ions reached the photobiont cells of the lichens containing higher amounts of secondary metabolites (lecanoric, fumarprotocetraric, stictic, constictic acids, antranorin). The results obtained support the putative role of some metabolites in heavy-metal tolerance of the lichens inhabiting metal-polluted habitats.
    Environmental and Experimental Botany 08/2011; 72(1):64-70. DOI:10.1016/j.envexpbot.2010.07.002 · 3.36 Impact Factor
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    Martin Bačkor · Evelin Ramóna Péli · Ivana Vantová ·
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    ABSTRACT: In this study we assessed the degree of copper (Cu) tolerance in two common lichen species (Cladonia furcata and Cladina arbuscula subsp. mitis) that grow on both uncontaminated substrata and the surface of waste heaps from abandoned old Cu-mines. Regardless of their locality, populations of these lichens contain identical strains of photobionts (Asterochloris clade A in C. arbuscula subsp. mitis and clade D in C. furcata). Therefore, it was expected that if there were differences in Cu toxicity or tolerance between populations, that the photobiont could not be a key element of Cu tolerance in these two lichen species. In laboratory experiments samples of both lichen species (from contaminated and control sites) were incubated in Cu solutions (500 μM) for 24 h. We attempted to determine whether Cu tolerance in these lichens was constitutive, or inducible form. Based on measurements of Cu accumulation, chlorophyll a integrity, chlorophyll a fluorescence, photosynthesis, respiration, measurements of the content of thiobarbituric acid reactive substances (TBARS), the content of soluble proteins, reactive oxygen species (ROS) and the amount of extracellular secondary metabolites of both lichens we found that there were no significant differences in the response of all selected populations of both lichen species to short-term exposure to these high levels of Cu. As a result, we conclude that Cu tolerance in these two lichen species is the constitutive rather than the inducible.
    Chemosphere 06/2011; 85(1):106-13. DOI:10.1016/j.chemosphere.2011.05.035 · 3.34 Impact Factor
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    ABSTRACT: Selected physiological responses of Tillandsia albida (Bromeliaceae) and two lichens (Hypogymnia physodes and Xanthoria parietina) exposed to simulated acid rain (AR) over 3 months were studied. Pigments were depressed in all species being affected the most in Tillandsia. Amounts of hydrogen peroxide and superoxide were elevated and soluble proteins decreased only in AR-exposed Hypogymnia. Free amino acids were slightly affected among species and only glutamate sharply decreased in AR-exposed Xanthoria. Slight increase in soluble phenols but decrease in flavonoids in almost all species suggests that the latter are not essential for tolerance to AR. Almost all phenolic acids in Tillandsia leaves decreased in response to AR and activities of selected enzymes (phenylalanine ammonia-lyase, polyphenol oxidase, ascorbate- and guaiacol-peroxidase) were enhanced by AR. In lichens, considerable increase in metabolites (physodalic acid, atranorin and parietin) in response to AR was found but amount of ergosterol was unchanged. Macronutrients (K, Ca, Mg) decreased more pronouncedly in comparison with micronutrients in all species. Xanthoria showed higher tolerance in comparison with Hypogymnia, suggesting that could be useful for long-term biomonitoring.
    Ecotoxicology 03/2011; 20(2):348-57. DOI:10.1007/s10646-010-0585-x · 2.71 Impact Factor
  • Tommaso Pisani · Silvana Munzi · Luca Paoli · Martin Bačkor · Stefano Loppi ·
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    ABSTRACT: The aim of this study was to test in a short term laboratory experiment the accumulation and physiological effects of As in the epiphytic lichen Xanthoria parietina. Arsenic content in treated samples increased progressively with increasing concentration in treatment solutions. Treatment of X. parietina thalli with 0.1, 1, 10 ppm As solutions caused significant decrease of viability, measured as intensity of respiratory activity, and damages to cell membranes, assessed by increase of electric conductivity of rinsing water and lipid peroxidation products. Soluble proteins content decreased and H₂O₂ content increased already at the lowest As concentration tested (0.01 ppm). Photosynthetic efficiency, measured in terms of F(V)/F(M) ratio, decreased significantly only at the highest As concentration (10 ppm). It was concluded that As exposure causes physiological stress both on the mycobiont and the photobiont and that cell membrane damage, expressed in terms of electric conductivity of rinsing water, is the parameter most affected by As treatment.
    Chemosphere 02/2011; 82(7):963-9. DOI:10.1016/j.chemosphere.2010.10.079 · 3.34 Impact Factor
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    ABSTRACT: One of the ways for searching for potentially new anti-cancer drugs is the testing of various naturally synthesized compounds. Lichens are a source of unique chemical agents of which some have already been proved to be effective against various cancer in vitro models. Our study reports on the sensitivity of up to nine human cancer cell lines (A2780, HeLa, MCF-7, SK-BR-3, HT-29, HCT-116 p53(+/+), HCT-116 p53(-/-), HL-60 and Jurkat) to the anti-proliferative/cytotoxic effects of four typical secondary metabolites of lichens (parietin, atranorin, usnic acid and gyrophoric acid). Variations in the dynamics of tumour cell line populations were evaluated by the MTT, clonogenic and viability assays, cell proliferation and detachment, cell cycle transition and apoptotic nuclear morphology, thereby confirming their concentration- and time-dependent cytotoxicity. However, in comparison with parietin and gyrophoric acid, the suppression of viability and cell proliferation by usnic acid or atranorin was found to be more efficient at equitoxic doses and correlated more strongly with an increased number of floating cells or a higher apoptotic index. Moreover, the analysis of cell cycle distribution also revealed an accumulation of cells in S-phase. This study has confirmed a differential sensitivity of cancer cell lines to lichen secondary metabolites.
    Toxicology in Vitro 02/2011; 25(1):37-44. DOI:10.1016/j.tiv.2010.09.004 · 2.90 Impact Factor

Publication Stats

1k Citations
167.31 Total Impact Points


  • 2004-2015
    • Pavol Jozef Šafárik University in Košice
      • Department of Botany
      Kassa, Košický, Slovakia
  • 2002-2009
    • The University of Western Ontario
      • Department of Biology
      London, Ontario, Canada
  • 1998
    • Comenius University in Bratislava
      • Department of Plant Physiology
      Bratislava, Bratislavsky Kraj, Slovakia