Nanotechnology, new fascinating field of science, is bringing many application's options. However, it is necessary to understand their potential environmental risk and toxicity. Zinc selenide quantum dots (ZnSe QDs) are getting valuable due to wide industrial usage, mainly as cadmium free diodes or stabilizing ligand. Thanks to unique properties, they could also open the possibilities of application in the agriculture. Their effects on living organisms, including plants, are still unknown. Therefore, the attention of this work was given to antioxidant response of Arabidopsis thaliana to 100 and 250 μM ZnSe QDs foliar feeding. ZnSe QDs treatment had no statistically significant differences in morphology but led to increased antioxidant response in the leaves at the level of gene expression and production secondary antioxidant metabolites. Concurrently, analysis of growth properties of Agrobacterium tumefaciens was done. 250 μM ZnSe solution inhibited the Agrobacterium tumefaciens viability by 60%. This is the first mention about effect ZnSe QDs on the plants. Although QDs induced oxidative stress, the apply treatment dose of ZnSe QDs did not have significant toxic effect on the plants and even no morphological changes were observed. However, the same amount of ZnSe QD induced an inhibitory effect on Agrobacterium tumefaciens.

• MeSH
• Agrobacterium tumefaciens účinky léků   růst a vývoj   MeSH
• antioxidancia metabolismus   MeSH
• Arabidopsis genetika   růst a vývoj   metabolismus   MeSH
• exprese genu * MeSH
• kvantové tečky toxicita   MeSH
• metabolomika * MeSH
• sloučeniny selenu aplikace a dávkování   toxicita   MeSH
• sloučeniny zinku aplikace a dávkování   toxicita   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

This paper reviews the current understanding of the toxicity of selenium (Se) to terrestrial mammalian and aquatic organisms. Adverse biological effects occur in the case of Se deficiencies, associated with this element having essential biological functions and a narrow window between essentiality and toxicity. Several inorganic species of Se (-2, 0, +4, and +6) and organic species (monomethylated and dimethylated) have been reported in aquatic systems. The toxicity of Se in any given sample depends not only on its speciation and concentration, but also on the concomitant presence of other compounds that may have synergistic or antagonistic effects, affecting the target organism as well, usually spanning 2 or 3 orders of magnitude for inorganic Se species. In aquatic ecosystems, indirect toxic effects, linked to the trophic transfer of excess Se, are usually of much more concern than direct Se toxicity. Studies on the toxicity of selenium nanoparticles indicate the greater toxicity of chemically generated selenium nanoparticles relative to selenium oxyanions for fish and fish embryos while oxyanions of selenium have been found to be more highly toxic to rats as compared to nano-Se. Studies on polymer coated Cd/Se quantum dots suggest significant differences in toxicity of weathered vs. non-weathered QD's as well as a significant role for cadmium with respect to toxicity.

• MeSH
• ekosystém MeSH
• krysa rodu rattus MeSH
• kvantové tečky toxicita   MeSH
• látky znečišťující životní prostředí toxicita   MeSH
• lidé MeSH
• organoselenové sloučeniny toxicita   MeSH
• skot MeSH
• sloučeniny kadmia toxicita   MeSH
• sloučeniny selenu toxicita   MeSH
• synergismus léků MeSH
• vodní organismy účinky léků   růst a vývoj   MeSH
• zvířata MeSH
• Check Tag
• krysa rodu rattus MeSH
• lidé MeSH
• skot MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• přehledy MeSH

Selenium is a trace element that is essential for living organism. Its beneficial effect is, however, expressed in a very narrow dosage range: the high and low doses of selenium are connected with pathological manifestations. The toxicity depends on the chemical form of selenium, state of organism, interactions with heavy metals and on the stage of ontogenetic development. Whereas one dose of sodium selenite (20 micromol/kg b.w.) is lethal in adult rats, suckling rats are entirely resistant. However, within one week after administration of the same dose, cataract of eye lens developed. The highest incidence of cataract was observed in 10-day-old animals and it decreased until day 20. From postnatal day 20 to day 40 the rats were resistant to both the lethal and cataractogenic effects of selenium. The incidence of cataract may be suppressed by premature weaning, lower hydration of suckling, change of water soluble/water insoluble lens protein ratio, thyroxine treatment, and by interaction with mercury. By means of its oxidative and reduction properties, selenium is involved in the maintenance of the cell redox homeostasis. Typical example is its possible cardioprotective effect: selenium decreased number of arrhythmias, reduced infarct size and improved the contractile recovery after ischemia/reperfusion injury. Selenium supplementation may thus increase cardiac tolerance to ischemic damage.

• MeSH
• infarkt myokardu patologie   prevence a kontrola   MeSH
• kardiotonika farmakologie   terapeutické užití   MeSH
• katarakta metabolismus   patologie   MeSH
• lidé MeSH
• oční čočka účinky léků   patologie   MeSH
• oxidace-redukce MeSH
• reperfuzní poškození myokardu patofyziologie   prevence a kontrola   MeSH
• sloučeniny selenu farmakologie   toxicita   MeSH
• srdeční arytmie patologie   prevence a kontrola   MeSH
• věkové faktory MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• přehledy 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
• 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

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