This work has analysed the influence of CdCl2, NiCl2 and CuCl2 on simple phenolic acids, such as the 3PPP (phenylpyruvic, phenylacetic, and 4-hydroxyphenylpyruvic) and 2DR (3,4-dihydroxyphenylacetic and rosmarinic) phenolic acids for the first time and studied their interactions with antioxidant systems and the glutathione-ascorbate cycle in the freshwater green microalga Scenedesmus quadricauda. The compounds investigated are related to both the catabolic and anabolic pathways of l-phenylalanine and l-tyrosine, the main molecules in the biosynthesis of polyphenols. The concentrations of the simple phenolic acids responded significantly to NiCl2, CdCl2 and CuCl2 at 5, 20 and 40 μM concentrations. The 3PPP phenolic acid concentrations after 24 h were always higher in metal-treated cells than in controls, while the 2DR concentrations were significantly lower in the metal-treated cells than the controls. The GSH/GSSG ratio was lower in all experimental groups treated with the selected metals (especially so at 40 μM). Pearson correlation analysis indicated a strong negative correlation between ascorbate and rosmarinic acid content (-0.670; p < 0.05) in NiCl2-treated samples and reduced glutathione and 3,4-dihydroxyphenylacetic content (-0.700; p < 0.05) in CdCl2-treated samples. The GSSG content in samples exposed to CuCl2 was correlated with the concentrations of all of the investigated phenolic acids (4 negative, 1 positive).

• Klíčová slova
• Ascorbate, Cadmium, Copper, Glutathione, Nickel, Oxidative stress, Scenedesmus quadricauda, Simple phenols,
• MeSH
• antioxidancia metabolismus   MeSH
• chlorid kademnatý toxicita   MeSH
• fytochelatiny metabolismus   MeSH
• glutathion metabolismus   MeSH
• hydroxybenzoáty metabolismus   MeSH
• kyselina askorbová metabolismus   MeSH
• měď toxicita   MeSH
• mikrořasy účinky léků   růst a vývoj   metabolismus   MeSH
• nikl toxicita   MeSH
• oxidační stres účinky léků   MeSH
• polyfenoly metabolismus   MeSH
• Scenedesmus účinky léků   růst a vývoj   metabolismus   MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• antioxidancia MeSH
• chlorid kademnatý MeSH
• cupric chloride MeSH Prohlížeč
• fytochelatiny MeSH
• glutathion MeSH
• hydroxybenzoáty MeSH
• kyselina askorbová MeSH
• měď MeSH
• nickel chloride MeSH Prohlížeč
• nikl MeSH
• phenolic acid MeSH Prohlížeč
• polyfenoly MeSH

Indirect impact of humic acid (HA) on metal accumulation and toxicity (Cd, Ni, Pb, and Hg; 100 μM; 24 h of exposure) in Scenedesmus quadricauda was studied. Algae were pre-cultured on solid (10 and 100 mg HA/L) or in liquid media (1, 5, and 10 mg HA/L) over 30 days and then exposed to metals mentioned above. Accumulation of applied metals irrespective of pre-culture increased in the order Ni < Cd < Pb < Hg. Algae pre-cultured on solid HA-enriched media accumulated more Cd (+ 46% at 10 mg HA/L), Ni (+ 50 and + 81% at 10 and 100 mg HA/L, respectively), and Pb (+ 15% at 100 mg HA/L) but the impact on Hg amount was not detected. Potassium and calcium decreased in response to all metals (K strongly under Hg excess) and HA had negligible impact. Interestingly, fluorescence microscopy detection of reactive oxygen species/nitric oxide (ROS/NO) balance showed that HA pre-culture suppressed ROS signal and stimulated NO signal in response to Cd (indicating positive impact of HA) while ROS signal in Ni and Pb treatments rather increased but NO signal decreased as expected from elevated Ni and Pb accumulation. Hg had clearly the most toxic impact on the ROS/NO balance. Algae pre-cultured in liquid HA-enriched media showed significantly increased Ni accumulation only (+ 14% at a dose 10 mg HA/L). Present study for the first time showed that humic acid may indirectly affect accumulation of metals and that solid HA-enriched medium used for pre-culture is more suitable to increase accumulation of metals by algae.

• Klíčová slova
• Bioaccumulation, Fluorescence microscopy, Heavy metals, Oxidative stress,
• MeSH
• chemické látky znečišťující vodu toxicita   MeSH
• fluorescenční mikroskopie MeSH
• huminové látky analýza   MeSH
• mikrořasy účinky léků   MeSH
• oxidační stres MeSH
• reaktivní formy kyslíku metabolismus   MeSH
• Scenedesmus účinky léků   MeSH
• testy akutní toxicity MeSH
• těžké kovy toxicita   MeSH
• vztah mezi dávkou a účinkem léčiva MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• chemické látky znečišťující vodu MeSH
• huminové látky MeSH
• reaktivní formy kyslíku MeSH
• těžké kovy MeSH

Despite the extensive research, the mechanism of the antimicrobial and biocidal performance of silver nanoparticles has not been unequivocally elucidated yet. Our study was aimed at the investigation of the ability of silver nanoparticles to suppress the growth of three types of algae colonizing the wetted surfaces or submerged objects and the mechanism of their action. Silver nanoparticles exhibited a substantial toxicity towards Chlorococcales Scenedesmus quadricauda, Chlorella vulgaris, and filamentous algae Klebsormidium sp., which correlated with their particle size. The particles had very good stability against agglomeration even in the presence of multivalent cations. The concentration of silver ions in equilibrium with nanoparticles markedly depended on the particle size, achieving about 6 % and as low as about 0.1 % or even less for the particles 5 nm in size and for larger ones (40-70 nm), respectively. Even very limited proportion of small particles together with larger ones could substantially increase concentration of Ag ions in solution. The highest toxicity was found for the 5-nm-sized particles, being the smallest ones in this study. Their toxicity was even higher than that of silver ions at the same silver concentration. When compared as a function of the Ag(+) concentration in equilibrium with 5-nm particles, the toxicity of ions was at least 17 times higher than that obtained by dissolving silver nitrite (if not taking into account the effect of nanoparticles themselves). The mechanism of the toxicity of silver nanoparticles was found complex with an important role played by the adsorption of silver nanoparticles and the ions released from the particles on the cell surface. This mechanism could be described as some sort of synergy between nanoparticles and ions. While our study clearly showed the presence of this synergy, its detailed explanation is experimentally highly demanding, requiring a close cooperation between materials scientists, physical chemists, and biologists.

• Klíčová slova
• Algae, Concentration of silver ions in equilibrium with silver nanoparticles, Silver ions, Silver nanoparticles, Toxicity, Uptake of silver by algae,
• MeSH
• antiinfekční látky metabolismus   toxicita   MeSH
• Chlorella vulgaris účinky léků   metabolismus   MeSH
• ionty metabolismus   MeSH
• kovové nanočástice toxicita   MeSH
• roztoky MeSH
• Scenedesmus účinky léků   metabolismus   MeSH
• stříbro metabolismus   toxicita   MeSH
• testy toxicity MeSH
• velikost částic MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• antiinfekční látky MeSH
• ionty MeSH
• roztoky MeSH
• stříbro MeSH

Responses of Scenedesmus quadricauda grown in vitro and differing in age (old culture-13 months, young culture-1 month) to short-term cadmium (Cd) or nickel (Ni) excess (24h) were compared. Higher age of the culture led to lower amount of chlorophylls, ascorbic acid and glutathione but higher signal of ROS. Surprisingly, sucrose was detected using DART-Orbitrap MS in both old and young culture and subsequent quantification confirmed its higher amount (ca. 3-times) in the old culture. Cd affected viability and ROS amount more negatively than Ni that could arise from excessive Cd uptake which was also higher in all treatments than in respective Ni counterparts. Surprisingly, nitric oxide was not extensively different in response to age or metals. Strong induction of phytochelatin 2 is certainly Cd-specific response while Ni also elevated ascorbate content. Krebs cycle acids were more accumulated in the young culture but they were rather elevated in the old culture (citric acid under Ni excess). We conclude that organic solid 'Milieu Bristol' medium we tested is suitable for long-term storage of unicellular green algae (also successfully tested for Coccomyxa sp. and Parachlorella sp.) and the impact of age on metal uptake may be useful for bioremediation purposes.

• Klíčová slova
• Aging, Antioxidants, Confocal microscopy, DART-Orbitrap MS, Oxidative stress,
• MeSH
• fytochelatiny metabolismus   MeSH
• kadmium farmakokinetika   toxicita   MeSH
• kyseliny karboxylové metabolismus   MeSH
• metabolom účinky léků   MeSH
• nikl farmakokinetika   toxicita   MeSH
• oxid dusnatý metabolismus   MeSH
• reaktivní formy kyslíku metabolismus   MeSH
• Scenedesmus účinky léků   růst a vývoj   metabolismus   MeSH
• sulfhydrylové sloučeniny metabolismus   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• fytochelatiny MeSH
• kadmium MeSH
• kyseliny karboxylové MeSH
• nikl MeSH
• oxid dusnatý MeSH
• reaktivní formy kyslíku MeSH
• sulfhydrylové sloučeniny MeSH

Physiological responses of Scenedesmus quadricauda to Cr(VI) and Cr(III) excess were studied in buffer with circumneutral pH (6.5). Total Cr content was similar in low (1 μM of both oxidation states) but higher in 10 μM Cr(VI) treatment and high accumulation potential was detected (80-82% and 41-65% in 1 and 10 μM treatments, respectively). Specific fluorescence indicator (6-((anthracen-9-yl) methyleneamino)-2H-chromen-2-one) confirmed partial reduction of Cr(VI) to Cr(III) under exposure conditions. Viability and chlorophyll autofluorescence were more depleted by Cr(VI) while Cr(III) stimulated increase in ROS and lipid peroxidation. Antioxidative enzyme activities showed significantly higher values in 10 μM treatments of both Cr oxidation states. Depletion of mitochondrial proteins was not reflected in alteration of total soluble proteins indicating sensitivity of this organelle to Cr and TTC test showed no clear oxidation state-related effect. In this view, "Cr(VI) is not more toxic than Cr(III)" at least for some parameters. Subsequent study with the application of 10 μM Cr(VI) confirmed that HEPES buffer is more suitable exposure solution for toxicological studied than water or inorganic salts (higher chlorophyll autofluorescence was observed) and pH 6.5 is more suitable than low or high pH (4.5 or 8.5) in terms of Cr uptake. Another known Cr(III) fluorescence indicator (naphthalimide-rhodamine) also confirmed partial reduction of Cr(VI) to Cr(III) at acidic pH but only traces were seen at alkaline pH.

• Klíčová slova
• Antioxidative enzymes, Bioaccumulation, Confocal/fluorescence microscopy, Heavy metals, Oxidative stress,
• MeSH
• chlorofyl metabolismus   MeSH
• chrom chemie   toxicita   MeSH
• fluorescence MeSH
• koncentrace vodíkových iontů MeSH
• látky znečišťující životní prostředí chemie   toxicita   MeSH
• mitochondriální proteiny metabolismus   MeSH
• oxidace-redukce MeSH
• peroxidace lipidů účinky léků   MeSH
• reaktivní formy kyslíku metabolismus   MeSH
• Scenedesmus účinky léků   fyziologie   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• chlorofyl MeSH
• chrom MeSH
• látky znečišťující životní prostředí MeSH
• mitochondriální proteiny MeSH
• reaktivní formy kyslíku MeSH

Impact of cytostatic drug 5-fluorouracil (FU) and its metabolite 2-fluoro-3-alanine (FA) on green alga Scenedesmus quadricauda was studied. FA elevated fluorescence signal of reactive oxygen species (ROS) more pronouncedly than FU at 1 and 10 μM doses while both ROS and reactive nitrogen species (RNS/NO) increased more expressively in 100 μM FU treatment. Cellular damage staining (Acridine Orange and Calcofluor White) did no reveal substantial difference between FU and FA. Majority of free amino acids including proline was unaffected after 24h of exposure. FA depleted ascorbate peroxidase activity more than FU therefore ascorbate content (AsA) was less affected while FU stimulated glutathione reductase activity less than FA and therefore glutathione (GSH) was more depleted. Both compounds accumulated concentration-dependently with higher absolute FA amounts but FU conversion to FA was also detected. We subsequently influenced 100 μM FU- and FA-induced changes using known ROS (DTT - dithiothreitol) and RNS/NO (SNP - sodium nitroprusside and PTIO - 2-phenyl-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide) modulators and results showed that PTIO depleted NO and elevated ROS while the opposite was found after SNP and DTT addition. Changes of lipid peroxidation (using BODIPY staining) confirmed that FU and FA toxicity is related to alteration of ROS/RNS balance.

• Klíčová slova
• Bioaccumulation, Confocal microscopy, Immunochemistry, Mass spectrometry, Nitric oxide,
• MeSH
• aminokyseliny metabolismus   MeSH
• biologický transport MeSH
• chemické látky znečišťující vodu škodlivé účinky   metabolismus   MeSH
• ekotoxikologie * MeSH
• fluoruracil škodlivé účinky   metabolismus   MeSH
• glutathion metabolismus   MeSH
• kyselina askorbová metabolismus   MeSH
• oxid dusnatý metabolismus   MeSH
• oxidační stres účinky léků   MeSH
• peroxidace lipidů MeSH
• reaktivní formy kyslíku metabolismus   MeSH
• Scenedesmus účinky léků   metabolismus   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• aminokyseliny MeSH
• chemické látky znečišťující vodu MeSH
• fluoruracil MeSH
• glutathion MeSH
• kyselina askorbová MeSH
• oxid dusnatý MeSH
• reaktivní formy kyslíku MeSH

Cyanobacteria pose a serious threat to water resources around the world. This is compounded by the fact that they are extremely resilient, having evolved numerous protective mechanisms to ensure their dominant position in their ecosystem. We show that treatment with nanoparticles of zerovalent iron (nZVI) is an effective and environmentally benign method for destroying and preventing the formation of cyanobacterial water blooms. The nanoparticles have multiple modes of action, including the removal of bioavailable phosphorus, the destruction of cyanobacterial cells, and the immobilization of microcystins, preventing their release into the water column. Ecotoxicological experiments showed that nZVI is a highly selective agent, having an EC(50) of 50 mg/L against cyanobacteria; this is 20-100 times lower than its EC(50) for algae, daphnids, water plants, and fishes. The primary product of nZVI treatment is nontoxic and highly aggregated Fe(OH)(3), which promotes flocculation and gradual settling of the decomposed cyanobacterial biomass.

• MeSH
• Araceae účinky léků   růst a vývoj   MeSH
• čištění vody metody   MeSH
• Daphnia účinky léků   fyziologie   MeSH
• hořčice rodu Sinapis účinky léků   růst a vývoj   MeSH
• kořeny rostlin účinky léků   růst a vývoj   MeSH
• kovové nanočástice toxicita   MeSH
• látky znečišťující vodu * analýza   MeSH
• listy rostlin účinky léků   růst a vývoj   MeSH
• Microcystis účinky léků   růst a vývoj   MeSH
• mikrobiologie vody MeSH
• mikrocystiny analýza   MeSH
• Scenedesmus účinky léků   růst a vývoj   MeSH
• železo toxicita   MeSH
• živorodka MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• látky znečišťující vodu * MeSH
• mikrocystiny MeSH
• železo MeSH

The function of selenium in an organism is mediated mostly by selenoproteins including glutathione peroxidase. Glutathione peroxidase is a potent anti-oxidative enzyme, scavenging a variety of peroxides. The green alga Scenedesmus quadricauda was used to investigate the relationship between the toxicity of selenium and the glutathione peroxidase activity. Selenium resistant strains SeIV and SeVI were synchronized and grown in high concentrations of Se (selenite or selenate). As a measure of selenium toxicity the EC(50) values were determined. During growth of the untreated wild type, glutathione peroxidase activity increased slightly and then declined gradually until the end of the cell cycle. A similar pattern was observed in untreated resistant strains and when resistant strains were grown in the presence of selenium in the oxidation state to which they were resistant. In the wild type cultivated with 50 mg Se L(-1) (selenite or selenate), activity increased to a high level and slowly declined until the end of the cell cycle. Similarly, activity increased in strains SeIV and SeVI when grown in the presence of selenium in the oxidation state to which they were not resistant. We followed the effect of selenium on the ultrastructure of S. quadricauda. After exposure to selenite, the chloroplast membranes of wild type were reorganized into thick bundles of thylakoids and the stroma became granulose. When selenate was added, the chloroplast of wild type had a fingerprint-like appearance, the stroma became less dense and starch production increased. In selenium resistant strains, when treated with the selenium form to which they were resistant, the chloroplast was affected, but not to such an extent as in the wild type. The activity of glutathione peroxidase in Scenedesmus was affected by selenium in an oxidation state-dependent manner. The most apparent effects of selenium on the ultrastructure involved impairment of the chloroplast and the overproduction of starch.

• MeSH
• buněčný cyklus účinky léků   fyziologie   MeSH
• chloroplasty účinky léků   metabolismus   ultrastruktura   MeSH
• fyziologický stres MeSH
• geneticky modifikované rostliny MeSH
• glutathionperoxidasa metabolismus   MeSH
• kultivační techniky MeSH
• kyselina selenová MeSH
• Scenedesmus cytologie   účinky léků   enzymologie   fyziologie   MeSH
• selen aplikace a dávkování   analýza   toxicita   MeSH
• seleničitan sodný aplikace a dávkování   toxicita   MeSH
• sloučeniny selenu aplikace a dávkování   toxicita   MeSH
• testy toxicity MeSH
• vztah mezi dávkou a účinkem léčiva MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• glutathionperoxidasa MeSH
• kyselina selenová MeSH
• selen MeSH
• seleničitan sodný MeSH
• sloučeniny selenu MeSH

BACKGROUND: Selenium is a trace element performing important biological functions in many organisms including humans. It usually affects organisms in a strictly dosage-dependent manner being essential at low and toxic at higher concentrations. The impact of selenium on mammalian and land plant cells has been quite extensively studied. Information about algal cells is rare despite of the fact that they could produce selenium enriched biomass for biotechnology purposes. RESULTS: We studied the impact of selenium compounds on the green chlorococcal alga Scenedesmus quadricauda. Both the dose and chemical forms of Se were critical factors in the cellular response. Se toxicity increased in cultures grown under sulfur deficient conditions. We selected three strains of Scenedesmus quadricauda specifically resistant to high concentrations of inorganic selenium added as selenite (Na2SeO3) - strain SeIV, selenate (Na2SeO4) - strain SeVI or both - strain SeIV+VI. The total amount of Se and selenomethionine in biomass increased with increasing concentration of Se in the culturing media. The selenomethionine made up 30-40% of the total Se in biomass. In both the wild type and Se-resistant strains, the activity of thioredoxin reductase, increased rapidly in the presence of the form of selenium for which the given algal strain was not resistant. CONCLUSION: The selenium effect on the green alga Scenedesmus quadricauda was not only dose dependent, but the chemical form of the element was also crucial. With sulfur deficiency, the selenium toxicity increases, indicating interference of Se with sulfur metabolism. The amount of selenium and SeMet in algal biomass was dependent on both the type of compound and its dose. The activity of thioredoxin reductase was affected by selenium treatment in dose-dependent and toxic-dependent manner. The findings implied that the increase in TR activity in algal cells was a stress response to selenium cytotoxicity. Our study provides a new insight into the impact of selenium on green algae, especially with regard to its toxicity and bioaccumulation.

• MeSH
• biomasa MeSH
• kyselina selenová MeSH
• Scenedesmus účinky léků   růst a vývoj   metabolismus   MeSH
• seleničitan sodný metabolismus   toxicita   MeSH
• selenomethionin metabolismus   MeSH
• síra metabolismus   MeSH
• sloučeniny selenu metabolismus   toxicita   MeSH
• thioredoxin-disulfidreduktasa metabolismus   MeSH
• vztah mezi dávkou a účinkem léčiva MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• kyselina selenová MeSH
• seleničitan sodný MeSH
• selenomethionin MeSH
• síra MeSH
• sloučeniny selenu MeSH
• thioredoxin-disulfidreduktasa MeSH

Synchronized cultures of the green alga Scenedesmus quadricauda were grown in the absence (untreated cultures) or in the presence (FdUrd-treated cultures) of 5-fluorodeoxyuridine, the specific inhibitor of nuclear DNA replication. The attainment of commitment points, at which the cells become committed to nuclear DNA replication, mitosis and cellular division, and the course of committed processes themselves were determined for cell cycle characterization. FdUrd-treated cultures showed nearly unaffected growth and attainment of the commitment points, while DNA replication(s), nuclear division(s) and protoplast fission(s) were blocked. Interestingly, the FdUrd-treated cells possessed a very high mitotic histone H1 kinase activity in the absence of any nuclear division(s). Compared with the untreated cultures, the kinase activity as well as mitotic cyclin B accumulation increased continuously to high values without any oscillation. Division of chloroplasts was not blocked but occurred delayed and over a longer time span than in the untreated culture. The FtsZ protein level in the FdUrd-treated culture did not exceed the level in the untreated culture, but rather, in contrast to the untreated culture, remained elevated. FtsZ structures were both localized around pyrenoids and spread inside of the chloroplast in the form of spots and mini-rings. The abundance and localization of the FtsZ protein were comparable in untreated and FdUrd-treated cells until the end of the untreated cell cycle. However, in the inhibitor-treated culture, the signal did not decrease and was localized in intense spots surrounding the chloroplast/cell perimeter; this was in agreement with both the elevated protein level and persisting chloroplast division.

• MeSH
• bílkoviny řas genetika   metabolismus   MeSH
• buněčný cyklus MeSH
• chloroplasty účinky léků   MeSH
• cyklin B metabolismus   MeSH
• DNA řas metabolismus   MeSH
• floxuridin farmakologie   MeSH
• molekulární sekvence - údaje MeSH
• proteinkinasy metabolismus   MeSH
• proteiny buněčného cyklu genetika   metabolismus   MeSH
• replikace DNA účinky léků   MeSH
• Scenedesmus účinky léků   genetika   růst a vývoj   MeSH
• sekvence aminokyselin MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• bílkoviny řas MeSH
• cyklin B MeSH
• DNA řas MeSH
• floxuridin MeSH
• histone H1 kinase MeSH Prohlížeč
• proteinkinasy MeSH
• proteiny buněčného cyklu MeSH