Biochemical and standard toxic effects of acetaminophen on the macrophyte species Lemna minor and Lemna gibba.

Science.gov (United States)

Nunes, Bruno; Pinto, Glória; Martins, Liliana; Gonçalves, Fernando; Antunes, Sara C

2014-09-01

Acetaminophen is globally one of the most prescribed drugs due to its antipyretic and analgesic properties. However, it is highly toxic when the dosage surpasses the detoxification capability of an exposed organism, with involvement of an already described oxidative stress pathway. To address the issue of the ecotoxicity of acetaminophen, we performed acute exposures of two aquatic plant species, Lemna gibba and Lemna minor, to this compound. The selected biomarkers were number of fronds, biomass, chlorophyll content, lipid peroxidation (TBARS assay), and proline content. Our results showed marked differences between the two species. Acetaminophen caused a significant decrease in the number of fronds (EC50 = 446.6 mg/L), and the establishment of a dose-dependent peroxidative damage in L. minor, but not in L. gibba. No effects were reported in both species for the indicative parameters chlorophyll content and total biomass. However, the proline content in L. gibba was substantially reduced. The overall conclusions point to the occurrence of an oxidative stress scenario more prominent for L. minor. However, the mechanisms that allowed L. gibba to cope with acetaminophen exposure were distinct from those reported for L. minor, with the likely involvement of proline as antioxidant.

Growth Recovery of Lemna gibba and Lemna minor Following a 7-Day Exposure to the Herbicide Diuron.

Science.gov (United States)

Burns, Mitchell; Hanson, Mark L; Prosser, Ryan S; Crossan, Angus N; Kennedy, Ivan R

2015-08-01

In agricultural catchments, aquatic ecosystems can experience a pulse exposure to pesticides. Following such exposure, non-target organisms that are not extirpated may recover. This paper investigates the potential of two duckweed species (Lemna minor and Lemna gibba) to recover from a 7-day exposure to different concentrations (0.4-208 µg L(-1)) of the herbicide diuron. There was significant inhibition in the growth and biomass after the initial 7-day exposure (e.g. frond number EC50=59.2 and 52.2 µg L(-1) for L. minor and L. gibba, respectively). Following transfer to clean media, recovery (the highest concentration yielding no significant difference in the effect endpoint from the control) was observed for all effects endpoints at concentrations ranging 60-111 µg L(-1) for L. minor and 60-208 µg L(-1) for L. gibba. These results suggest that recovery is possible for primary producers at environmentally relevant concentrations considered significant in ecological risk assessment.

Comparative study of compounds of primary exchange duckweed (Lemna minor L., trisulki duckweed (Lemna trisulca L. and spirodela (Spirodella polyrrhiza L. Schleid.

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L. A. Nikiforov

2017-01-01

Full Text Available The purpose of the paper is to study qualitative composition and quantitative content of primary exchange compounds in duckweed (Lemna minor L., trisulki duckweed (Lemna trisulca L. and spirodela (Spirodella polyrrhiza (L. Schleid.Materials and methods. The subject of the study was air-dried samples of grass collected during their 2010- 2011 growing season in low-flow and stagnant water bodies of Kozhevnikovsky and Tomsk districts of the Tomsk region. The concentration of free monosaccharides was determined by direct-phase high-performance liquid chromatography. The concentration of the bound sugars was determined by capillary electrophoresis using Applied Biosystem 273T (Thermophischer Ltd., USA. To obtain data on the qualitative composition and quantitative content of amino acids, the amino acid analyzer Hitachi 835 (Japan was used.Results. It was found out that the least amount of amino acids contained in the water extract from duckweed trifoliate – 96,14 mg, which is 2 times less than in extracts of Lemna minor and Lemna multirooted (205,65 and 208,38 mg, respectively. In duckweed the minimum content of free and bound monosaccharides was determined to be 10,54%, while in the Lemna trifoliate and Lemna multirooted their content was 14,30% and 15,35%, respectively. This study showed the qualitative and quantitative differences of free and bound monosaccharide and amino acid composition between previously mentioned species. 

Fate of antimicrobials in duckweed Lemna minor wastewater treatment systems.

Science.gov (United States)

Iatrou, Evangelia I; Gatidou, Georgia; Damalas, Dimitrios; Thomaidis, Nikolaos S; Stasinakis, Athanasios S

2017-05-15

The fate of four antimicrobials (cefadroxil, CFD; metronidazole, METRO; trimethoprim, TRI; sulfamethoxazole, SMX) was studied in Lemna minor systems and the role of different mechanisms on their removal was evaluated. All micropollutants were significantly removed in batch experiments with active Lemna minor; the highest removal was observed for CFD (100% in 14 d), followed by METRO (96%), SMX (73%) and TRI (59%) during 24 d of the experiment. Calculation of kinetic constants for hydrolysis, photodegradation, sorption to biomass and plant uptake revealed significant differences depending on the compound and the studied mechanism. For METRO, TRI and SMX the kinetic constants of plant uptake were by far higher comparing to those of the other mechanisms. The transformation products of antimicrobials were identified using UHPLC-QToF-MS. Two were the main degradation pathways for TRI; hydroxylation takes place during both phyto- and photodegradation, while demethylation occurs only in absence of Lemna minor. The operation of a continuous-flow duckweed system showed METRO and TRI removal equal to 71±11% and 61±8%, respectively. The application of mass balance and the use of published biodegradation constants showed that plant uptake and biodegradation were the major mechanisms governing METRO removal; the most important mechanism for TRI was plant uptake. Copyright © 2017 Elsevier B.V. All rights reserved.

Control of the Protein Turnover Rates in Lemna minor

Science.gov (United States)

Trewavas, A.

1972-01-01

The control of protein turnover in Lemna minor has been examined using a method described in the previous paper for determining the rate constants of synthesis and degradation of protein. If Lemna is placed on water, there is a reduction in the rate constants of synthesis of protein and an increase (3- to 6-fold) in the rate constant of degradation. The net effect is a loss of protein from the tissue. Omission of nitrate, phosphate, sulfate, magnesium, or calcium results in increases in the rate constant of degradation of protein. An unusual dual effect of benzyladenine on the turnover constants has been observed. Treatment of Lemna grown on sucrose-mineral salts with benzyladenine results in alterations only in the rate constant of synthesis. Treatment of Lemna grown on water with benzyladenine alters only the rate constant of degradation. Abscisic acid on the other hand alters both rate constants of synthesis and degradation of protein together. Inclusion of growth-inhibiting amino acids in the medium results in a reduction in the rate constants of synthesis and increases in the rate constant of degradation of protein. It is concluded that the rate of turnover of protein in Lemna is very dependent on the composition of the growth medium. Conditions which reduce growth rates also reduce the rates of synthesis of protein and increase those of degradation. PMID:16657895

DEVELOPMENT OF THE DUCKWEED (LEMNA MINOR GENETIC TRANSFORMATION SYSTEM

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Sofia E Gaydukova

2008-12-01

Full Text Available Regeneration parameters were optimized and effective selection conditions were sorted out. Transgenic plants of Lemna minor were obtained and their status was confirmed by molecular analysis. Optimized methodology can be used for obtaining transgenic duckweed plants producing recombinant proteins and water body bioremediators.

Ecotoxicological assessments show sucralose and fluoxetine affect the aquatic plant, Lemna minor

Energy Technology Data Exchange (ETDEWEB)

Amy-Sagers, Cherisse; Reinhardt, Keith; Larson, Danelle M., E-mail: danellelarson77@gmail.com

2017-04-15

Highlights: • Sucralose increased leaf area and photosynthetic capacity of Lemna minor. • Sucralose increased δ {sup 13}C of Lemna, indicating substantial uptake and assimilation. • 100 μg/L-fluoxetine decreased Lemna minor growth and asexual reproduction. - Abstract: Pharmaceuticals and personal care products (PPCP) are prevalent in aquatic systems, yet the fate and impacts on aquatic plants needs quantification for many compounds. We measured and detected sucralose (an artificial sweetener), fluoxetine (an antidepressant), and other PPCP in the Portneuf River in Idaho, USA, where Lemna minor (an aquatic plant in the environment and used in ecotoxicology studies) naturally occurs. Sucralose was hypothesized to negatively affect photosynthesis and growth of L. minor because sucralose is a chlorinated molecule that may be toxic or unusable for plant metabolism. A priori hypotheses were not created for fluoxetine due to lack of previous studies examining its impacts on plants. We conducted laboratory ecotoxicological assessments for a large range of concentrations of sucralose and fluoxetine on L. minor physiology and photosynthetic function. Frond green leaf area, root length, growth rate, photosynthetic capacity, and plant carbon isotopic composition (discrimination relative to a standard; δ{sup 13}C) were measured among treatments ranging from 0 to 15000 nmol/L-sucralose and 0–323 nmol/L-fluoxetine. Contrary to our predictions, sucralose significantly increased green leaf area, photosynthetic capacity, and δ {sup 13}C of L. minor at environmentally relevant concentrations. The increase of δ {sup 13}C from sucralose amendments and an isotope-mixing model indicated substantial sucralose uptake and assimilation within the plant. Unlike humans who cannot break down and utilize sucralose, we documented that L. minor—a mixotrophic plant—can use sucralose as a sugar substitute to increase its green leaf area and photosynthetic capacity. Fluoxetine

Ecotoxicological assessments show sucralose and fluoxetine affect the aquatic plant, Lemna minor

International Nuclear Information System (INIS)

Amy-Sagers, Cherisse; Reinhardt, Keith; Larson, Danelle M.

2017-01-01

Highlights: • Sucralose increased leaf area and photosynthetic capacity of Lemna minor. • Sucralose increased δ "1"3C of Lemna, indicating substantial uptake and assimilation. • 100 μg/L-fluoxetine decreased Lemna minor growth and asexual reproduction. - Abstract: Pharmaceuticals and personal care products (PPCP) are prevalent in aquatic systems, yet the fate and impacts on aquatic plants needs quantification for many compounds. We measured and detected sucralose (an artificial sweetener), fluoxetine (an antidepressant), and other PPCP in the Portneuf River in Idaho, USA, where Lemna minor (an aquatic plant in the environment and used in ecotoxicology studies) naturally occurs. Sucralose was hypothesized to negatively affect photosynthesis and growth of L. minor because sucralose is a chlorinated molecule that may be toxic or unusable for plant metabolism. A priori hypotheses were not created for fluoxetine due to lack of previous studies examining its impacts on plants. We conducted laboratory ecotoxicological assessments for a large range of concentrations of sucralose and fluoxetine on L. minor physiology and photosynthetic function. Frond green leaf area, root length, growth rate, photosynthetic capacity, and plant carbon isotopic composition (discrimination relative to a standard; δ"1"3C) were measured among treatments ranging from 0 to 15000 nmol/L-sucralose and 0–323 nmol/L-fluoxetine. Contrary to our predictions, sucralose significantly increased green leaf area, photosynthetic capacity, and δ "1"3C of L. minor at environmentally relevant concentrations. The increase of δ "1"3C from sucralose amendments and an isotope-mixing model indicated substantial sucralose uptake and assimilation within the plant. Unlike humans who cannot break down and utilize sucralose, we documented that L. minor—a mixotrophic plant—can use sucralose as a sugar substitute to increase its green leaf area and photosynthetic capacity. Fluoxetine significantly

Productivity of duckweed (Lemna minor as alternative forage feed for livestock in different light intensities

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Uti Nopriani

2015-12-01

Full Text Available Duckweed (Lemna minor is a small aquatic plant that grow and float in water and spread extensively. Lemna minor is potential as a source of high quality forage. This study aimed to determine optimal light intensity on Lemna minor to generate maximum productivity. Parameters observed were physical-biological and chemical characteristics of the media (pH value, temperature, cover area, decreased of media volume, BOD, COD, nitrate, nitrite and phosphate, plant growth acceleration (number of shoots, leaf diameter and chlorophyll-a, biomass production, doubling time of cover area and the number of daughters. This study was done based on a completely randomized design with 4 levels of shading. While treatment was: without shading, shading 30%, shading 50% and shading 70% using paranet shade. Each treatment consisted of 4 replications. Result showed that the productivity of Lemna minor included the number of daughters, chlorophyll-a, biomass production, cover area, absorbed phosphate and doubling time the number of daughters reached the highest level without shading treatment (1007,21-2813,57 lux. The decrease of intensity of light, the increase the diameter of leaf. Decrease of media volume was positively correlated to size of cover area. Biomass production influenced by a wide doubling time of cover area and number of daughters.

A FLOW-THROUGH TESTING PROCEDURE WITH DUCKWEED (LEMNA MINOR L.)

Science.gov (United States)

Lemna minor is one of the smallest flowering plants. Because of its floating habit, ease of culture, and small size it is well adapted for laboratory investigations. Procedures for flow-through tests were developed. Testing procedures were developed with this apparatus. By using ...

NEW METHOD FOR DETERMINING EFFLUENT TOXICITY USING DUCKWEED (LEMNA MINOR)

Science.gov (United States)

Duckweed (Lemna minor), a small vascular plant, grows rapidly, is sensitive to a wide variety of toxicants and is easy to culture. ethod is described that measures duckweed frond growth and chlorophyll levels as indicators of growth inhibition. he method requires a small testing ...

Competition Between Lemna minuta, Lemna minor, and Azolla filiculoides. Growing Fast or Being Steadfast?

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Simona Paolacci

2018-06-01

Full Text Available A substantial number of Lemnaceae are invasive outside their natural distribution area. Lemna minuta is considered invasive in several European countries, where it can occur in the same habitat as invasive Azolla filiculoides and native Lemna minor. In this study the presence, abundance and growth rates of all three species were monitored across 24 natural ponds and in a series of mesocosms in order to explore the importance of species invasiveness and habitat invisibility. Field monitoring showed that the distribution of the three species of macrophytes is heterogeneous in space and time. However, the data show no association of nutrient or light levels with plant distribution. Indeed, using reciprocal transplanting experiments it was demonstrated that all species are able to grow in all ponds, even ponds where the species do not naturally occur. It is concluded that distribution of L. minor, L. minuta, and A. filiculoides is not limited by the prevailing physicochemical characteristics of the ponds during the summer period. Remarkably, in these experiments A. filiculoides displayed the highest RGR, and exerted a negative influence on growth rates and surface cover of L. minor and L. minuta. Despite such apparent invasiveness, A. filiculoides was relatively rare in the study area. Rather, the species most abundant was L. minor which has the lowest RGR under field conditions in summer. Therefore, this study shows that the invasiveness of the species during the summer months is not necessarily reflected in the actual distribution pattern in natural ponds. In fact, alien L. minuta and A. filiculoides are under-represented in the monitored area. It is concluded that the interaction of several factors, including growth under winter-conditions and/or dispersal after disturbances, is the major determinant of the abundance and heterogeneous distribution of L. minor, L. minuta, and A. filiculoides in the study area.

Effect of circulation on wastewater treatment by Lemna gibba and Lemna minor (floating aquatic macrophytes).

Science.gov (United States)

Demirezen Yilmaz, Dilek; Akbulut, Hatice

2011-01-01

In this study, laboratory tests were performed in order to examine growth characteristics of floating aquatic macrophytes (Lemna gibba and Lemna minor) in the presence of wastewater with circulation. The results showed that circulation of the waste water enhanced the kinetics of the process, as compared to the control systems. However, prolonged application of high circulation level had a different effect. In the presence of circulation with aquatic plants, there was additional 85.3-88.2% for BODs and 59.6-66.8% for COD decreases in the water quality indicators. In this study, the effectiveness of L. gibba and L. minor with circulation addition for the removal of four heavy metals (Pb, Ni, Mn, and Cu) from waste water was also investigated. Results from analysis confirmed the accumulation of different metals within the plant and a corresponding decrease of metals in the waste water. At the end of the study of circulation, L. gibba provided the metal removal for Cu, Pb, Ni, and Mn in the waste water as the ratio of 57%, 60%, 60%, and 62%, respectively. In this context, the best results were obtained when the action of L. gibba and L. minor plants, was combined with that of circulation. It is shown that in the presence of L. gibba and L. minor plants that are supplemented with circulation, the national standards of biochemical oxygen demand (BOD5) 27-33 mgL(-1) and chemical oxygen demand (COD) 62-78 mgL(-1) for L. minor and L. gibba, respectively, were reached after treatment. The new results can be used for design calculations regarding expected removal of pollutants by aquatic floating plants.

Ecological differentiation of Lemna minor L. and Spirodela polyrrhiza (L. Schleiden populations

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Hanna Wożakowska-Natkaniec

2015-01-01

Full Text Available The subject of thep resent study are 19 natural, ecological populations of Lemna minor and Spirodela polyrrhiza coming from sixteen habitats in Lower Silesia. The study showed the essential differences between ecological populations of both species, conditioned on chemistry (pH, level N, P, K, Ca, Mg and Fe and the natural water radioactivity. It was shown experimentally that these populations, in nature, establish a set of ecotypes or ecophene variability. Ecotypic differentiation of populations of Lemna minor and Spirodela polyrrhiza is based upon individual features and population characteristics such as: shape and size of plants, plant frequency of two, three, and four fronds, the ratio of right- to left-handed plants, and the dynamics of growth and biomass production.

Physiology and plastic fine structure of deetiolating Lemna minor

Energy Technology Data Exchange (ETDEWEB)

Frick, H; Jones, R F

1976-08-01

During the 12-h lag period in chlorophyll accumulation after the onset of white-light illumination of Lemna minor etiolated for 35 days, a rapid increase in visible fronds per culture occurred. This new frond production then assumed a log-linear rate of increase, and total protein per unit fresh weight came to parallel the rate of increase in fresh weight per plant. The ribosomal RNA content of 45-day-etiolated plants was deficient in 23S and 16S species compared with green plants. The prolamellar bodies of etioplasts were either tightly or loosely paracrystalline within the same cell; they were without extended perforate lamellae, which developed during far-redlight illumination even while prolamellar bodies persisted. The development of chloroplasts in deetiolating L. minor was typical of other higher plants. The developmental sequence in green Lemna included proplastid to deeply stacked granal chloroplast within several millimeters. Plastid profiles suggestive of division configurations occurred only in primordial cells of green and etiolated plants. The relatively small numbers of plastids in any given stage of differentation may account for the sensitivity of plastid development to inhibitors of protein and nucleic acid synthesis.

EVALUACIÓN DE LA PLANTA Lemna minor COMO BIORREMEDIADORA DE AGUAS CONTAMINADAS CON MERCURIO

OpenAIRE

Adolfo D. Arenas; Lué-Merú Marcó; Gosmyr Torres

2011-01-01

Se evaluó la capacidad biorremediadora de Lemna minor en función del tiempo en aguas contaminadas con mercurio mediante un diseño experimental de 3 bloques al azar con cinco réplicas: un grupo experimental con 100 g de Lemna, 7,5 L de agua contaminada con Hg (0,13 mgL-1) y solución nutritiva; un grupo Testigo con 100 g de Lemna, 7,5 L de agua y solución nutritiva y un grupo control con mercurio al nivel de 0,13 mgL-1 en agua destilada sin plantas. La eficiencia de remoción de mercurio de la L...

Boron accumulation by Lemna minor L. under salt stress.

Science.gov (United States)

Liu, Chunguang; Gu, Wancong; Dai, Zheng; Li, Jia; Jiang, Hongru; Zhang, Qian

2018-06-12

Excess boron (B) is toxic to aquatic organisms and humans. Boron is often present in water with high salinity. To evaluate the potential of duckweed (Lemna minor L.) for removing B from water under salt stress, we cultured duckweed in water with 2 mg/L of B and sodium chloride (NaCl) concentrations ranging from 0 to 200 mM for 4 days. The results show that with increasing salinity, the capacity of L. minor to accumulate B initially decreased and then increased. L. minor used different mechanisms to accumulate boron at lower and higher levels of salt stress. The growth and chlorophyll synthesis of L. minor were significantly inhibited when the concentration of NaCl reached 100 mM. Our results suggest that L. minor is suitable for the accumulation of B when NaCl salinity is below 100 mM.

Study of 137Cs absorption by Lemna minor

International Nuclear Information System (INIS)

Bergamini, P.G.; Palmas, G.; Piantelli, F.; Sani, M.; Banditelli, P.; Previtera, M.; Sodi, F.

1979-01-01

Absorption of 137 Cs by the floating aquatic plant Lemna Minor in relation to 137 Cs concentration in the water was measured under controlled conditions of temperature, pH and light. The method used to analyse the results is described. When applied to this study the method shows the influence on 137 Cs absorption of (1) potassium-cesium exchange due to chemical affinity, (2) the natural colony growth of the organism and (3) the effect of light. Concentration factors were determined for these three processes. (author)

Orthophosphate modulates the phytotoxicity of nano-ZnO to Lemna minor (L.).

Science.gov (United States)

Chen, Xiaolin; O'Halloran, John; Jansen, Marcel A K

2018-03-02

Because of their applications in large numbers of products, Zinc Oxide nanoparticles (nano-ZnO) will inevitably enter into the environment. Nano-ZnO released into the environment will be present in a complex matrix which can cause various chemical and physical transformations and modulate the biological reactivity of these particles. Due to their rapid growth and small size, Lemna minor is recommended by OECD for toxicological testing. Here, we tested how nano-ZnO reactivity is modulated by the suite of macro- and micronutrients that are present in Lemna minor growth media. Specifically, we measured ex situ Reactive Oxygen Species (ROS) formation by nano-ZnO, and subsequent in planta toxicity. The data show how orthophosphate can modulate both ex situ ROS formation, and in planta toxicity. This has ramifications for phytotoxicity testing, which is commonly performed under controlled conditions and on media containing orthophosphate.

Batch Removal of Acid Blue 292dye by Biosorption onto Lemna minor: Equilibrium and Kinetic Studies

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Ali Joghataei

2016-12-01

Full Text Available Background: Recently, there has been a great concern about the consumption of dyes because of their toxicity, mutagenicity, carcinogenicity, and persistence in the aquatic environment. Therefore, the aim of this study was to determine the feasibility of using Lemna minor for Acid Blue 292 (AB292 dye removal from aqueous solution and to determine the optimal conditions. Methods: This experimental study was conducted in the batch systems to investigate the effects of parameters such as contact time, initial concentration of dye, pH and Lemna minor biomass dose. Isotherms and kinetic studies of dye adsorption were performed using equilibrium data. Results: According to the results, a maximum removal efficiency of 98.5% was obtained at pH of 3 and the contact time of 90 min; initial dye concentration 10 mg/L and adsorbent dose 3g/L. The adsorption data was best fitted to the Langmuir isotherm and pseudo-second order kinetic model. Conclusion: The results showed that Lemna minor could be used as a cost-effective adsorbent for removing AB292 dye from textile wastewater efficiently.

Effects of light and phytochrome in heterotrophic growth of Lemna minor L.

NARCIS (Netherlands)

Rombach, J.

1976-01-01

Axenic cultures of Lemna minor L. were grown on a medium containing sugars and amino acids. In continuous darkness the growth rate was one-tenth of the maximum in continuous light. In darkness early death revealed a thiamine deficiency; this

Efficient transformation and artificial miRNA gene silencing in Lemna minor.

Science.gov (United States)

Cantó-Pastor, A; Mollá-Morales, A; Ernst, E; Dahl, W; Zhai, J; Yan, Y; Meyers, B C; Shanklin, J; Martienssen, R

2015-01-01

Despite rapid doubling time, simple architecture and ease of metabolic labelling, a lack of genetic tools in the Lemnaceae (duckweed) has impeded the full implementation of this organism as a model for biological research. Here, we present technologies to facilitate high-throughput genetic studies in duckweed. We developed a fast and efficient method for producing Lemna minor stable transgenic fronds via Agrobacterium-mediated transformation and regeneration from tissue culture. Additionally, we engineered an artificial microRNA (amiRNA) gene silencing system. We identified a Lemna gibba endogenous miR166 precursor and used it as a backbone to produce amiRNAs. As a proof of concept we induced the silencing of CH42, a magnesium chelatase subunit, using our amiRNA platform. Expression of CH42 in transgenic L. minor fronds was significantly reduced, which resulted in reduction of chlorophyll pigmentation. The techniques presented here will enable tackling future challenges in the biology and biotechnology of Lemnaceae. © 2014 German Botanical Society and The Royal Botanical Society of the Netherlands.

Ecotoxicological evaluation of two anti-dandruff hair shampoos using Lemna minor.

Science.gov (United States)

Azizullah, Azizullah; Shakir, Shakirullah Khan; Shoaib, Shahana; Bangash, Halima; Taimur, Nadia; Murad, Waheed; Daud, Muhammad Khan

2018-04-04

Hair shampoos, a mixture of various organic and organic compounds, are commonly used personnel care products. Since shampoos are used in almost every household and beauty shop, their ingredients are common components of domestic and municipal wastewater. However, studies on the effect of shampoos to aquatic plants can hardly be found in literature. Therefore, the present study was conducted to investigate the phytotoxic effects of two commonly used anti-dandruff shampoos (named here AD 1 and AD 2) using Lemna minor as a biotest organism. For toxicity assessment, frond number, fresh and dry biomass, and light-harvesting pigments (chlorophyll a, b and total carotenoids) of Lemna were used as end points. Five different concentrations (0.001, 0.01, 0.1, 1, and 5%) of each shampoo were tested in comparison to the control. At lower concentrations of shampoos, some minor and non-significant stimulatory effects were observed in some parameters, but at concentrations above 0.01% both the shampoos significantly inhibited almost all parameters in Lemna. The EC 50 values obtained for frond number were 0.034 and 0.11% for AD 1 and AD 2, respectively. The fresh biomass gave EC 50 values of 0.07 and 0.066% for AD 1 and AD 2, respectively. Based on the preset study, it can be speculated that shampoo contamination at higher concentrations in water bodies can be a threat to aquatic organisms. This study can be used as a baseline to further investigate shampoo toxicity using other species and to explore the mechanism of shampoo toxicity in aquatic plants.

Trophic transfer of cadmium from duckweed (Lemna Minor L.) to Tilapia (Oreochromis mossambicus)

NARCIS (Netherlands)

Xue, Yan; Peijnenburg, Willie J G M; Huang, Jin; Wang, Dengjun; Jin, Yan

2018-01-01

The transfer of the toxic heavy metal Cd from duckweed (Lemna minor L.) to the freshwater fish tilapia (Oreochromis mossambicus) was investigated. Concentrations of Cd in different chemical forms in duckweed and in different tissues (gut, edible muscle, and remnants) of tilapia, i.e.,

Toxicity of sodium chloride and methyl parathion on the macrophyte Lemna minor (Linnaeus, 1753 with respect to frond number and chlorophyll

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Erlei Cassiano Keppeler

2009-09-01

Full Text Available Duckweed, Lemna minor L., is a suitable plant model for toxicity evaluation of many contaminants due to its small size and rapid growth. Methyl parathion is a toxic compound which is utilized to eliminate aquatic insect larvae, among other purposes. Its toxicity was evaluated with the use of L. minor in this study. Methyl parathion was added to Hoagland’s nutrient medium at concentrations of 0, 8, 16, 22, 28 and 32mg.L–1. Lemna minor is used as a tool in evaluating chemical test products for toxic effects. The sensitivity of Lemna to sodium chloride, the reference substance, at concentrations of 0, 2, 4, 6, 7 and 8 g.L–1, was determined for comparison and resulted in an IC50 of 6.87g.L–1. Methyl parathion in L. minor showed an IC50 of 49.48mg.L–1.

Study of /sup 137/Cs absorption by Lemna minor

Energy Technology Data Exchange (ETDEWEB)

Bergamini, P G; Palmas, G; Piantelli, F; Sani, M [Siena Univ. (Italy). Ist. di Fisica; Banditelli, P; Previtera, M; Sodi, F

1979-09-01

Absorption of /sup 137/Cs by the floating aquatic plant Lemna minor in relation to /sup 137/Cs concentration in the water was measured under controlled conditions of temperature, pH and light. The method used to analyse the results is described. When applied to this study the method shows the influence on /sup 137/Cs absorption of (1) potassium-cesium exchange due to chemical affinity, (2) the natural colony growth of the organism and (3) the effect of light. Concentration factors were determined for these three processes.

The enzymatic and antioxidative stress response of Lemna minor to copper and a chloroacetamide herbicide.

Science.gov (United States)

Obermeier, Michael; Schröder, Christian A; Helmreich, Brigitte; Schröder, Peter

2015-12-01

Lemna minor L., a widely used model plant for toxicity tests has raised interest for its application to phytoremediation due to its rapid growth and ubiquitous occurrence. In rural areas, the pollution of water bodies with heavy metals and agrochemicals poses a problem to surface water quality. Among problematic compounds, heavy metals (copper) and pesticides are frequently found in water bodies. To establish duckweed as a potential plant for phytoremediation, enzymatic and antioxidative stress responses of Lemna minor during exposure to copper and a chloroacetamide herbicide were investigated in laboratory studies. The present study aimed at evaluating growth and the antioxidative and glutathione-dependent enzyme activity of Lemna plants and its performance in a scenario for phytoremediation of copper and a chloroacetamide herbicide. Lemna minor was grown in Steinberg medium under controlled conditions. Plants were treated with CuSO4 (ion conc. 50 and 100 μg/L) and pethoxamide (1.25 and 2.5 μg/L). Measurements following published methods focused on plant growth, oxidative stress, and basic detoxification enzymes. Duckweed proved to survive treatment with the respective concentrations of both pollutants very well. Its growth was inhibited scarcely, and no visible symptoms occurred. On the cellular basis, accumulation of O2(-) and H2O2 were detected, as well as stress reactions of antioxidative enzymes. Duckweed detoxification potential for organic pollutants was high and increased significantly with incubation. Pethoxamide was found to be conjugated with glutathione. Copper was accumulated in the fronds at high levels, and transient oxidative defense reactions were triggered. This work confirms the significance of L. minor for the removal of copper from water and the conjugation of the selective herbicide pethoxamide. Both organic and inorganic xenobiotics induced different trends of enzymatic and antioxidative stress response. The strong increase of stress

Possible ecological risk of two pharmaceuticals diclofenac andparacetamol demonstrated on a model plant Lemna minor

Czech Academy of Sciences Publication Activity Database

Kummerová, M.; Zezulka, Š.; Babula, P.; Tříska, Jan

2016-01-01

Roč. 302, jan (2016), s. 351-361 ISSN 0304-3894 Institutional support: RVO:67179843 Keywords : Antioxidant mechanism * Diclofenac * Lemna minor * Oxidative stress * Paracetamol Subject RIV: EH - Ecology, Behaviour Impact factor: 6.065, year: 2016

Toxicity of sodium chloride and methyl parathion on the macrophyte Lemna minor (Linnaeus, 1753 with respect to frond number and chlorophyll

Directory of Open Access Journals (Sweden)

Erlei Cassiano Keppeler

2009-06-01

Full Text Available http://dx.doi.org/10.5007/2175-7925.2009v22n3p27 Duckweed, Lemna minor L., is a suitable plant model for toxicity evaluation of many contaminants due to its small size and rapid growth. Methyl parathion is a toxic compound which is utilized to eliminate aquatic insect larvae, among other purposes. Its toxicity was evaluated with the use of L. minor in this study. Methyl parathion was added to Hoagland’s nutrient medium at concentrations of 0, 8, 16, 22, 28 and 32mg.L–1. Lemna minor is used as a tool in evaluating chemical test products for toxic effects. The sensitivity of Lemna to sodium chloride, the reference substance, at concentrations of 0, 2, 4, 6, 7 and 8 g.L–1, was determined for comparison and resulted in an IC50 of 6.87g.L–1. Methyl parathion in L. minor showed an IC50 of 49.48mg.L–1.

Toxicological implications of selenium nanoparticles with different coatings along with Se4+ on Lemna minor.

Science.gov (United States)

Tarrahi, Roshanak; Khataee, Alireza; Movafeghi, Ali; Rezanejad, Farkhondeh; Gohari, Gholamreza

2017-08-01

Nanoparticles have potential high risks for living organisms in the environment due to their specific qualities and their easy access. In the present study, selenium nanoparticles (Se NPs) with two different coatings (l-cysteine and tannic acid) were synthesized. The characteristics of particles were analyzed using XRD, FT-IR and SEM. The impact of the nanoparticles besides Se 4+ , on the aquatic higher plant Lemna minor was evaluated and compared. Entrance of l-cysteine and tannic acid capped Se NPs in the roots of Lemna minor was proved by TEM and fluorescence microscopy. Adverse effects of mentioned NPs and differences of these effects from those by sodium selenite as the ionic form were assessed by a range of biophysicochemical tests. Altogether, the results asserted that Lemna minor was notably poisoned by both capped Se NPs and Se 4+ . Thus, growth and photosynthetic pigments were decreased while lipid peroxidation along with total phenol and flavonoid contents were raised. Eventually some changes in enzymatic activities were presented. To sum up the consequences, it can be concluded that all changes occurred due to the plant defense system especially in order to remove reactive oxygen species (ROS) and possible phytotoxicity originated by l- cysteine and tannic acid capped Se NPs in addition to Se 4+ . The influence of tannic acid capped Se NPs after sodium selenite is stronger by the means of antioxidant enzymes activity in comparison with l-cysteine capped Se NPs. Copyright © 2017 Elsevier Ltd. All rights reserved.

Apport du traitement d'images dans le suivi de l'influence des teneurs en nutriments sur la croissance des lentilles d'eau (Lemna minor

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Tangou, TT.

2014-01-01

Full Text Available Contribution of image processing in monitoring the influence of nutrients on the growth of duckweed (Lemna minor. The growth of duckweed (Lemna minor is an important component in the treatment process in wastewater floating macrophyte ponds. An excess or shortage of this biomass may be responsible for the dysfunction of such ponds. Modeling these duckweed ponds through mass balances based on Petersen's matrix may be helpful in facilitating the optimal management of such facilities. This study sought to assess the efficiency of digital image processing in the growth monitoring of Lemna minor under different concentrations of nitrogen and phosphorus. The experiments were carried out in a growth chamber (phytotron using an experimental pilot involving initial fresh Lemna minor biomass (1 g, nitrogen and phosphorus concentrations varying between 5 and 64 mg N-NH4+·l-1, and 1 and 24 mg P-PO43-·-1, respectively. Digital image processing was achieved in addition to gravimetric methods (fresh weight and/or dry weight. Our results showed that the image processing method allowed a continuous and non-destructive monitoring of duckweed biomass. The growth of Lemna minor progressively decreased when nitrogen and phosphorus concentrations were greater than 16 mg N-NH4+·l-1 and 6 mg P-PO43-·-1. The maximum growth rates μmax were of the order of 0.07 d-1. The kinetic constants KS and KI were respectively 3.83 mg·l-1 and 204 mg·l-1 for nitrogen, and 1.26 mg·l-1 and 13.3 mg·l-1 for phosphorus. Such results are interesting as they could contribute to the optimal management of Lemna minor and the modeling of biological reactors.

The first draft genome of the aquatic model plant Lemna minor opens the route for future stress physiology research and biotechnological applications.

Science.gov (United States)

Van Hoeck, Arne; Horemans, Nele; Monsieurs, Pieter; Cao, Hieu Xuan; Vandenhove, Hildegarde; Blust, Ronny

2015-01-01

Freshwater duckweed, comprising the smallest, fastest growing and simplest macrophytes has various applications in agriculture, phytoremediation and energy production. Lemna minor, the so-called common duckweed, is a model system of these aquatic plants for ecotoxicological bioassays, genetic transformation tools and industrial applications. Given the ecotoxic relevance and high potential for biomass production, whole-genome information of this cosmopolitan duckweed is needed. The 472 Mbp assembly of the L. minor genome (2n = 40; estimated 481 Mbp; 98.1 %) contains 22,382 protein-coding genes and 61.5 % repetitive sequences. The repeat content explains 94.5 % of the genome size difference in comparison with the greater duckweed, Spirodela polyrhiza (2n = 40; 158 Mbp; 19,623 protein-coding genes; and 15.79 % repetitive sequences). Comparison of proteins from other monocot plants, protein ortholog identification, OrthoMCL, suggests 1356 duckweed-specific groups (3367 proteins, 15.0 % total L. minor proteins) and 795 Lemna-specific groups (2897 proteins, 12.9 % total L. minor proteins). Interestingly, proteins involved in biosynthetic processes in response to various stimuli and hydrolase activities are enriched in the Lemna proteome in comparison with the Spirodela proteome. The genome sequence and annotation of L. minor protein-coding genes provide new insights in biological understanding and biomass production applications of Lemna species.

Toxic Effect of Bispyribac-sodium and Cu^2+ on Lemna Minor%双草醚和Cu对浮萍的毒性效应

Institute of Scientific and Technical Information of China (English)

郑丽英

2012-01-01

The single toxic and combined toxic effects of Cu^2+ and bispyribac-sodium on Lemna minor were studied.The results showed that Cu2+ could stimulate the growth of Lemna minor and affect on the content of chlorophyll when the concentration of Cu^2+ was below 0.2 mg/L.With the increasing of the treatment concentration of Cu^2+,the growth rate of Lemna minor decreased.When its concentration was more than 0.4 mg/L,the growth of Lemna minor and the content of chlorophyll would be significantly affected.When the concentration of bispyribac-sodium was beyond 0.02 mg/L,Lemna minor's growth was obviously inhibited.The joint toxicity of Cu2+ and bispyribac-sodium would inhibit the growth of Lemna minor in concentration 1:1,and the toxicity of combined pollution is obviously greater than those of single pollution.%应用水培实验方法,研究了重金属铜和除草剂双草醚对浮萍的单一毒性和联合毒性效应。结果表明：当Cu^2＋浓度小于0.2 mg/L,可促进浮萍生长;当浓度达到0.4 mg/L时对浮萍生长产生毒害。双草醚浓度高于0.02 mg/L时,对浮萍生长有显著的抑制作用。相同浓度的Cu2＋和双草醚按1∶1等体积混合时明显抑制浮萍生长,且浓度增加,对浮萍生长的毒害效应也逐步增强,叶绿素a的含量明显下降。复合污染对浮萍生长的影响明显大于单一污染,表现为协同作用。

cpDNA microsatellite markers for Lemna minor (Araceae): Phylogeographic implications.

Science.gov (United States)

Wani, Gowher A; Shah, Manzoor A; Reshi, Zafar A; Atangana, Alain R; Khasa, Damase P

2014-07-01

A lack of genetic markers impedes our understanding of the population biology of Lemna minor. Thus, the development of appropriate genetic markers for L. minor promises to be highly useful for population genetic studies and for addressing other life history questions regarding the species. • For the first time, we characterized nine polymorphic and 24 monomorphic chloroplast microsatellite markers in L. minor using DNA samples of 26 individuals sampled from five populations in Kashmir and of 17 individuals from three populations in Quebec. Initially, we designed 33 primer pairs, which were tested on genomic DNA from natural populations. Nine loci provided markers with two alleles. Based on genotyping of the chloroplast DNA fragments from 43 sampled individuals, we identified one haplotype in Quebec and 11 haplotypes in Kashmir, of which one occurs in 56% of the genotypes, one in 8%, and nine in 4%, respectively. There was a maximum of two alleles per locus. • These new chloroplast microsatellite markers for L. minor and haplotype distribution patterns indicate a complex phylogeographic history that merits further investigation.

Enhanced plant regeneration in lemna minor by amino acids

International Nuclear Information System (INIS)

Yang, L.; Han, H.; Zhou, K.; Ren, C.; Zhu, Y.

2014-01-01

In present study we investigated the effects of different L-amino acids on the plant regeneration from callus of Lemna minor, and established an efficient protocol. Among the 20 L-amino acids, only L-Ser and L-Gly showed significant improving effect, with the optimal concentration being 1 mM and 1.5 mM, respectively. A regeneration frequency of 46% was observed when the callus transferred to the regeneration medium with addition of 1 mM L-Ser for 11 days. After 26 days of cultivation, the frond regeneration achieved 100% and 94% for 1 mM L-Ser and 1.5 mM L-Gly treatment, respectively. (author)

Effect of electromagnetic fields on duckweed (lemna minor) and alga (chlorella kessleri)

International Nuclear Information System (INIS)

Tkalec, M.; Malaric, K.; Malaric, R.; Vidakovic-Cifrek, Z.; Pevalek-Kozlina, B.

2005-01-01

Electricity produces extremely low frequency fields (50-60 Hz) while various kinds of radiofrequency fields (10 MHz-300 GHz) are used to transmit information (TV, radio, mobile phones and satellite communications). Duckweed (Lemna minor) and green algae (Chlorella kessleri) were exposed to the magnetic field of 50 Hz in a Helmholtz coil, to an electric field of 50 Hz between two parallel circle electrodes, and to electromagnetic fields of 400 and 900 MHz in a Gigahertz Transversal Electromagnetic Mode cell. The relative growth of Lemna minor exposed to extremely low frequency alternating magnetic field of 50 Hz (1 mT) for 24 hours was slightly reduced at the beginning of the experiment while a 50 Hz electric field (25 kV/m) slightly reduced its growth during the second week of the experiment. Radio frequencies of 400 and 900 MHz (23 V/m) applied for two hours decreased the duckweed growth after the third day, but only 900 MHz affected it significantly. The rate of photosynthesis in green algae increased after exposure to the magnetic field of 50 Hz, but decreased after exposure to the electric field of 50 Hz. Radio frequencies of 400 and 900 MHz generally increased its rate of photosynthesis.(author)

Response of Lemna minor L. to short-term cobalt exposure: The effect on photosynthetic electron transport chain and induction of oxidative damage

International Nuclear Information System (INIS)

Begović, Lidija; Mlinarić, Selma; Antunović Dunić, Jasenka; Katanić, Zorana; Lončarić, Zdenko; Lepeduš, Hrvoje; Cesar, Vera

2016-01-01

Highlights: • Cobalt (Co"2"+) impaired the function of oxygen evolving complex (OEC) in L. minor L. • Electron transport through PSII components varied depending on Co"2"+ concentration. • K-band was proven to be suitable parameter for investigation of Co"2"+ toxicity. • Increased lipid peroxidation level showed early oxidative damage induced by Co"2"+. - Abstract: The effect of two concentrations of cobalt (Co"2"+) on photosynthetic activity and antioxidative response in Lemna minor L. were assessed 24, 48 and 72 h after the start of the exposure. Higher concentration of cobalt (1 mM) induced growth inhibition while lower concentration (0.01 mM) increased photosynthetic pigments content. Analysis of chlorophyll a fluorescence transients revealed high sensitivity of photosystem II primary photochemistry to excess of Co"2"+ especially at the higher concentration where decreased electron transport beyond primary quinone acceptor Q_A"− and impaired function of oxygen evolving complex (OEC) was observed. Due to impairment of OEC, oxygen production was decreased at higher Co"2"+ concentration. Activity of superoxide dismutase was mainly inhibited while lipid peroxidation increased, at both concentrations, indicating that cobalt-induced oxidative damage after short exposure and moreover, susceptibility of the membranes in the cell to cobalt toxicity. Results obtained in this study suggest possible application of used parameters as tools in assessment of early damage caused by metals.

Potential use of Lemna minor for the phytoremediation of isoproturon and glyphosate.

Science.gov (United States)

Dosnon-Olette, Rachel; Couderchet, Michel; Oturan, Mehmet A; Oturan, Nihal; Eullaffroy, Philippe

2011-07-01

Pesticides are being detected in water bodies on an increasingly frequent basis. The present study focused on toxicity and phytoremediation potential of aquatic plants to remove phytosanitary products from contaminated water. We investigated the capacity of Lemna minor (L. minor) to eliminate two herbicides isoproturon and glyphosate from their medium. Since phytoremediation relies on healthy plants, pesticide toxicity was evaluated by exposing plants to 5 concentrations (0-20 microg L(-1) for isoproturon and 0-120 microg L(-1) for glyphosate) in culture media for 4 d using growth rate and chlorophyll a fluorescence as endpoints. At exposure concentrations of 10 microg x L(-1) for isoproturon and 80 microg x L(-1) for glyphosate, effects on growth rate and chlorophyll fluorescence were minor (isoproturon and glyphosate, respectively.

LA LENTEJA DE AGUA (LEMNA MINOR L.: UNA PLANTA ACUÁTICA PROMISORIA*

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María del Pilar Arroyave

Full Text Available Se describen las principales características morfológicas y ecológicas de la planta acuática Lemna minor L., al igual que la utilización que tiene como complemento alimenticio para animales domésticos y en labores de fitorremediación, por su capacidad de absorber nutrientes y contaminantes de los ecosistemas acuáticos. Asimismo se discute su potencial como una especie adecuada para realizar ensayos de fitotoxicidad.

Oxidative stress in duckweed (Lemna minor L.) induced by glyphosate: Is the mitochondrial electron transport chain a target of this herbicide?

Science.gov (United States)

Gomes, Marcelo Pedrosa; Juneau, Philippe

2016-11-01

We investigated the physiological responses of Lemna minor plants exposed to glyphosate. The deleterious effects of this herbicide on photosynthesis, respiration, and pigment concentrations were related to glyphosate-induced oxidative stress through hydrogen peroxide (H 2 O 2 ) accumulation. By using photosynthetic and respiratory electron transport chain (ETC) inhibitors we located the primary site of reactive oxygen species (ROS) production in plants exposed to 500 mg glyphosate l -1 . Inhibition of mitochondrial ETC Complex I by rotenone reduced H 2 O 2 concentrations in glyphosate-treated plants. Complex III activity was very sensitive to glyphosate which appears to act much like antimycin A (an inhibitor of mitochondrial ETC Complex III) by shunting electrons from semiquinone to oxygen, with resulting ROS formation. Confocal evaluations for ROS localization showed that ROS are initially produced outside of the chloroplasts upon initial glyphosate exposure. Our results indicate that in addition to interfering with the shikimate pathway, glyphosate can induce oxidative stress in plants through H 2 O 2 formation by targeting the mitochondrial ETC, which would explain its observed effects on non-target organisms. Copyright © 2016 Elsevier Ltd. All rights reserved.

cpDNA Microsatellite Markers for Lemna minor (Araceae: Phylogeographic Implications

Directory of Open Access Journals (Sweden)

Gowher A. Wani

2014-07-01

Full Text Available Premise of the study: A lack of genetic markers impedes our understanding of the population biology of Lemna minor. Thus, the development of appropriate genetic markers for L. minor promises to be highly useful for population genetic studies and for addressing other life history questions regarding the species. Methods and Results: For the first time, we characterized nine polymorphic and 24 monomorphic chloroplast microsatellite markers in L. minor using DNA samples of 26 individuals sampled from five populations in Kashmir and of 17 individuals from three populations in Quebec. Initially, we designed 33 primer pairs, which were tested on genomic DNA from natural populations. Nine loci provided markers with two alleles. Based on genotyping of the chloroplast DNA fragments from 43 sampled individuals, we identified one haplotype in Quebec and 11 haplotypes in Kashmir, of which one occurs in 56% of the genotypes, one in 8%, and nine in 4%, respectively. There was a maximum of two alleles per locus. Conclusions: These new chloroplast microsatellite markers for L. minor and haplotype distribution patterns indicate a complex phylogeographic history that merits further investigation.

Farklı pH Değerlerinin Lemna gibba L. ve Lemna minor L.’de Nikel Alınımı ve Klorofi lMiktarına Etkisi

OpenAIRE

URUÇ, Kadriye; YILMAZ, Dilek DEMİREZEN; AKBULUT, Hatice

2008-01-01

In this study, the effect of different pH on the nickel absorbtion capacity and amount of chlorophyll of Lemna minor and Lemna gibba was investigated under laboratory conditions.At high pH value (pH = 7), we observed increasing amount of kla and klb with increasing pH. Additionally, nickel accumulation capacity was signifi cantly reduced at pH 4. It means, nickel absorbtion capacity was stimulated by an decrease in pH value. Furthermore, considerably higher accumulation of nickel were found i...

Bioremediation of an iron-rich mine effluent by Lemna minor.

Science.gov (United States)

Teixeira, S; Vieira, M N; Espinha Marques, J; Pereira, R

2014-01-01

Contamination of water resources by mine effluents is a serious environmental problem. In a old coal mine, in the north of Portugal (São Pedro da Cova, Gondoma),forty years after the activity has ended, a neutral mine drainage, rich in iron (FE) it stills being produced and it is continuously released in local streams (Ribeiro de Murta e Rio Ferreira) and in surrounding lands. The species Lemna minor has been shown to be a good model for ecotoxicological studies and it also has the capacity to bioaccumulate metals. The work aimed test the potential of the species L. minor to remediate this mine effluent, through the bioaccumulation of Fe, under greenhouse experiments and, at the same time, evaluate the time required to the maximum removal of Fe. The results have shown that L. minor was able to grow and develop in the Fe-rich effluent and bioaccumulating this element. Throughout the 21 days of testing it was found that there was a meaningful increase in the biomass of L. minor both in the contaminated and in the non-contaminated waters. It was also found that bioaccumulation of Fe (iron) occurred mainly during the first 7 days of testing. It was found that L. minor has potential for the bioremediation of effluents rich in iron.

Model for Stress-induced Protein Degradation in Lemna minor1

Science.gov (United States)

Cooke, Robert J.; Roberts, Keith; Davies, David D.

1980-01-01

Transfer of Lemna minor fronds to adverse or stress conditions produces a large increase in the rate of protein degradation. Cycloheximide partially inhibits stress-induced protein degradation and also partially inhibits the protein degradation which occurs in the absence of stress. The increased protein degradation does not appear to be due to an increase in activity of soluble proteolytic enzymes. Biochemical evidence indicates that stress, perhaps acting via hormones, affects the permeability of certain membranes, particularly the tonoplast. A general model for stress-induced protein degradation is presented in which changes in membrane properties allow vacuolar proteolytic enzymes increased access to cytoplasmic proteins. PMID:16661588

Lead pollution: poisonous effects on plants. [Phalanis canariensis; Lemna minor

Energy Technology Data Exchange (ETDEWEB)

Fiussello, N

1973-01-01

Lead alkyl additives in motor gasoline emitted into the atmosphere are responsible for the high levels of lead in soil and plants near roads. The A has tested the poisonousness of lead salts against the germination and growth of wheat, oats and Phalaris canariensis. Concentrations of 10-/sup 2/ M lead nitrate inhibit, in part, wheat germination and totally oats and P. - canariensis germination. In sand cultures with a lead content of 200 p.p.m. there is a diminution of fresh weight, of dry weight and of the chlorophyll content. Water plants (Lemna minor) are remarkably damaged by lead nitrate (200 p.p.m. conc.). 5 references.

Effect of gamma-radiation on demographic and morphometric parameters of laboratory population of duckweed Lemna minor

International Nuclear Information System (INIS)

Rasskazova, M.M.; Berestina, A.V.

2015-01-01

After effect of chronic gamma-exposition on Lemna minor plants, significantly decreases the specific rate of population growth, increases the process of frond's dying-off. The chronic exposition with radiation intensity 5,0 Gy/hour induces roots growth and significantly increased percent of damaged fronds. (authors)

Response of Lemna minor L. to short-term cobalt exposure: The effect on photosynthetic electron transport chain and induction of oxidative damage

Energy Technology Data Exchange (ETDEWEB)

Begović, Lidija, E-mail: lbegovic@biologija.unios.hr [Josip Juraj Strossmayer University of Osijek, Department of Biology, Ulica cara Hadrijana 8/A, H R -31000 Osijek (Croatia); Mlinarić, Selma, E-mail: smlinaric@biologija.unios.hr [Josip Juraj Strossmayer University of Osijek, Department of Biology, Ulica cara Hadrijana 8/A, H R -31000 Osijek (Croatia); Antunović Dunić, Jasenka, E-mail: jantunovic@biologija.unios.hr [Josip Juraj Strossmayer University of Osijek, Department of Biology, Ulica cara Hadrijana 8/A, H R -31000 Osijek (Croatia); Katanić, Zorana, E-mail: zkatanic@biologija.unios.hr [Josip Juraj Strossmayer University of Osijek, Department of Biology, Ulica cara Hadrijana 8/A, H R -31000 Osijek (Croatia); Lončarić, Zdenko, E-mail: zdenko.loncaric@pfos.hr [Faculty of Agriculture, Josip Juraj Strossmayer University of Osijek, Ulica kralja Petra Svačića 1d, H R -31000 Osijek (Croatia); Lepeduš, Hrvoje, E-mail: hlepedus@yahoo.com [Faculty of Humanities and Social Sciences, Josip Juraj Strossmayer University of Osijek, Lorenza Jägera 9, HR-31000 Osijek (Croatia); Cesar, Vera, E-mail: vcesarus@yahoo.com [Josip Juraj Strossmayer University of Osijek, Department of Biology, Ulica cara Hadrijana 8/A, H R -31000 Osijek (Croatia)

2016-06-15

Highlights: • Cobalt (Co{sup 2+}) impaired the function of oxygen evolving complex (OEC) in L. minor L. • Electron transport through PSII components varied depending on Co{sup 2+} concentration. • K-band was proven to be suitable parameter for investigation of Co{sup 2+} toxicity. • Increased lipid peroxidation level showed early oxidative damage induced by Co{sup 2+}. - Abstract: The effect of two concentrations of cobalt (Co{sup 2+}) on photosynthetic activity and antioxidative response in Lemna minor L. were assessed 24, 48 and 72 h after the start of the exposure. Higher concentration of cobalt (1 mM) induced growth inhibition while lower concentration (0.01 mM) increased photosynthetic pigments content. Analysis of chlorophyll a fluorescence transients revealed high sensitivity of photosystem II primary photochemistry to excess of Co{sup 2+} especially at the higher concentration where decreased electron transport beyond primary quinone acceptor Q{sub A}{sup −} and impaired function of oxygen evolving complex (OEC) was observed. Due to impairment of OEC, oxygen production was decreased at higher Co{sup 2+} concentration. Activity of superoxide dismutase was mainly inhibited while lipid peroxidation increased, at both concentrations, indicating that cobalt-induced oxidative damage after short exposure and moreover, susceptibility of the membranes in the cell to cobalt toxicity. Results obtained in this study suggest possible application of used parameters as tools in assessment of early damage caused by metals.

Toxicity assessment of boron (B) by Lemna minor L. and Lemna gibba L. and their possible use as model plants for ecological risk assessment of aquatic ecosystems with boron pollution.

Science.gov (United States)

Gür, Nurcan; Türker, Onur Can; Böcük, Harun

2016-08-01

As many of the metalloid-based pollutants, the boron (B) toxicity issues have aroused more and more global attentions, especially concerning drinking water sources which flow through boron-rich areas. Therefore, feasible and innovative approaches are required in order to assess B toxicity in aquatic ecosystems. In this study, the toxic effects of B on Lemna minor L. and Lemna gibba L. were investigated using various endpoints including number of fronds, growth rates, dry biomass and antioxidants enzymatic activities. Lemna species were exposed to B concentrations of 2 (control), 4, 8, 16, 32, 64 and 128 mg L(-1) for a test period of 7 days. The results demonstrated that plant growth was significantly reduced when the B concentration reached 16 mg L(-1). Furthermore, our results also concluded that among the antioxidative enzymes, SOD, APX and GPX can serve as important biomarkers for B-rich environment. The present results suggested that L. minor and L. gibba are very useful model plants for phytoremediation of low-B contaminated wastewater and they are also suitable options for B biomonitoring due to high phototoxic sensitivity against B. In this respect, the scientific insight of the present study is to fill the gaps in the research about the use of L. minor and L. gibba in ecotoxicological research associated with B toxicity. Copyright © 2016 Elsevier Ltd. All rights reserved.

Reduction in photosynthetic efficiency of Cladophora glomerata, induced by overlying canopies of Lemna spp.

Science.gov (United States)

Parr, L B; Perkins, R G; Mason, C F

2002-04-01

The duckweeds Lemna minor L. and L. minuscula Herter reduced PSII quantum efficiency (F'q/F'm) of the filamentous green alga Cladophora glomerata Kützing by up to 42% over seven days when floating above mats of C. glomerata in containers. Dissolved oxygen (DO) increased by 23% at 30 degrees C in containers with C. glomerata over controls. But when the water surface in the containers was covered with Lemna spp. floating above C. glomerata, DO was 83% lower at 30 degrees C over seven days than in control samples with no duckweed or alga. Dissolved oxygen was lower beneath a thick mat (1 cm) of either Lemna spp. covering the surface than under a thin layer (single-frond canopy). PAM fluorimetry showed that maximum PSII efficiency (Fv/Fm) of C. glomerata in containers was reduced under a canopy of L. minor by 17% over seven days, and under L. minuscula by 22%. F'q/F'm of C. glomerata in containers exposed to 51 micromol m(-2) s(-1) PPFD decreased under a canopy of L. minor by 16% over seven days, and under L. minuscula by 19% compared to controls. When light response curves were compared, F'q/F'm was significantly reduced under canopies of L. minor at the highest temperatures tested (28 degrees C and 30 degrees C). L. minor significantly reduced relative electron transport rate (rel. ETR) of the controls by up to 71% at 30 degrees C. Relative electron transport rate did not reach light saturation point (Esat) except at 28 degrees and 30 degrees C under mats of L. minor. Whereas the highest rate of production (rel. ETRmax) and Esat increased with temperature in controls, under a canopy of Lemna, decreases were observed. It is suggested that, during periods of high summer temperature and irradiance, shading inhibits oxygenic photosynthesis in mats of C. glomerata beneath canopies of Lenma spp. This results in less oxygen being produced by the C. glomerata (oxygen produced by Lemna spp. is not released into the water), and this may further inhibit the C. glomerata by

Effects of growth, development and reproduction of Tenebrio molitor by feeding Lemna minor%饲喂浮萍对黄粉虫生长发育及繁殖的影响

Institute of Scientific and Technical Information of China (English)

王清春; 刘玉升; 方加兴

2017-01-01

为探索浮萍Lemna minor生物质利用新途径,解决浮萍在污水中引起的二次污染现象,本研究利用黄粉虫Tenebrio molitor L食性杂,易饲养,可转化利用多种有机生物质资源的的特性,将浮萍烘干、磨碎后,与麦麸配制成50％浮萍∶50％麦麸,60％浮萍∶40％麦麸,70％浮萍∶30％麦麸,80％浮萍∶20％麦麸不同比例的混合饲料(加水使饲料含水量保持为18％)来饲养黄粉虫幼虫(以纯麦麸为对照组);同时以浮萍替代豆饼作为添加料,按照白菜∶麦麸∶浮萍=10∶4∶1做成混合饲料饲养成虫,来研究浮萍对黄粉虫生长发育及繁殖的影响.结果显示:与纯麦麸相比,幼虫试验中各处理组的生物量增长率、饲料利用率均降低,死亡率增高,而饲喂“50％浮萍∶50％麦麸”饲料的黄粉虫幼虫的各指标与对照组差异不显著,为最佳浮萍饲料配比;在成虫试验中,以浮萍为添加料的成虫单雌产卵量为586.33±6.84粒,成虫寿命为105.5 ±1.43 d,均显著高于以豆饼为添加料的对照组.本研究对利用黄粉虫转化处理浮萍的效果做出了初步评价,即黄粉虫取食转化浮萍是可行的,为浮萍的生物质利用提供参考.%In order to explore the utilization of Lemna minor biomass in new ways,and to solve the second pollution phenomenon caused by it in wastewater.In the study,we make use of some characteristics of Tenebrio molitor L.,such as omnivorous,easy to breed and can utilizate of a variety of organic biomass resources,to transform and utilize Lemna minor.First,we dried Lemna minor to constant weight and mixed with wheat bran in different proportions (add water to keep the water content of these artificial diet at 18％):"50％ Lemna minor∶ 50％wheat bran","60％ Lemna minor:40％ wheat bran","70％ Lemna minor∶30％ wheat bran","80％ Lemna minor∶20％ wheat bran" to feed Tenebrio molitor larvae (pure wheat bran as the control group);Then,we use Lemna

A NEW APPROACH FOR CULTURING LEMNA MINOR (DUCKWEED) AND STANDARDIZED METHOD FOR USING ATRAZINE AS A REFERENCE TOXICANT

Science.gov (United States)

Lemna minor (Duckweed) is commonly used in aquatic toxicity investigations. Methods for culturing and testing with reference toxicants, such as atrazine, are somewhat variable among researchers. Our goal was to develop standardized methods of culturing and testing for use with L....

Researchin chronic low-level gamma -irradiation on laboratory populations of Lemna minor

International Nuclear Information System (INIS)

Rasskazova, M.M.; Berestina, A.V.

2012-01-01

Researching carried out on the laboratory population of Lemna minor showed that the chronically γ-irradiated plants significantly reduced specific rate of population growth, accelerating the process of withering away of the fronds. Chronic irradiation with dose of 5,0 mGy/h stimulates the growth of the roots, and irradiation with a capacity of 50 mGy/h significantly increases the percentage of damage fronds. Found out independent of dose effect on the criterion of the number of deaths of individuals in the range of absorbed dose between 0,01 - 1 Gy. (authors)

cpDNA microsatellite markers for Lemna minor (Araceae): Phylogeographic implications1

Science.gov (United States)

Wani, Gowher A.; Shah, Manzoor A.; Reshi, Zafar A.; Atangana, Alain R.; Khasa, Damase P.

2014-01-01

• Premise of the study: A lack of genetic markers impedes our understanding of the population biology of Lemna minor. Thus, the development of appropriate genetic markers for L. minor promises to be highly useful for population genetic studies and for addressing other life history questions regarding the species. • Methods and Results: For the first time, we characterized nine polymorphic and 24 monomorphic chloroplast microsatellite markers in L. minor using DNA samples of 26 individuals sampled from five populations in Kashmir and of 17 individuals from three populations in Quebec. Initially, we designed 33 primer pairs, which were tested on genomic DNA from natural populations. Nine loci provided markers with two alleles. Based on genotyping of the chloroplast DNA fragments from 43 sampled individuals, we identified one haplotype in Quebec and 11 haplotypes in Kashmir, of which one occurs in 56% of the genotypes, one in 8%, and nine in 4%, respectively. There was a maximum of two alleles per locus. • Conclusions: These new chloroplast microsatellite markers for L. minor and haplotype distribution patterns indicate a complex phylogeographic history that merits further investigation. PMID:25202636

Study of the influence of platinum, palladium and rhodium on duckweed (Lemna minor).

Science.gov (United States)

Bednarova, Ivana; Mikulaskova, Hana; Havelkova, Barbora; Strakova, Lenka; Beklova, Miroslava; Sochor, Jiri; Hynek, David; Adam, Vojtech; Kizek, Rene

2014-01-01

Road traffic pollutants and the residues of cytostatics that are widely used in anti-cancer therapy are a significant sources of platinum group elements (PGE; Pt, Pd and Rh) in environment. These metals can migrate into sewage and thus pollute surface waters. The purpose of our study was to evaluate the effect of PtCl4 on the antioxidant and enzymatic activity of duckweed (Lemna minor), a bioindicator of the aquatic environment. The study was performed using a 7-day conventional test based on the OECD 221 (CSN EN ISO 20079)--Lemna sp. Growth Inhibition Test. We also conducted a microbiotest to analyse the effects of PtC4, PdCl2 and RhCl3 on the morphology and vegetative growth of colonies of this plant and compared their inhibitory effects during the microbiotest. We observed inhibition of colony growth and clear morphological changes. Antioxidant and enzymatic activities increased with platinum doses increased. The 168hEC50 of PtCl4 was 12.16 μM (95% confidence interval = 9.88-14.44) and the 168hEC50 of PdCl2 was 50.39 (95% confidence interval = 23.83-76.96). The greatest inhibition of growth by RhCl3 was observed at 25 μM. The obtained results suggest that L. minor phytotoxicity tests should be widely used in the biomonitoring.

Investigation of biomass production, crude protein and starch content in laboratory wastewater treatment systems planted with Lemna minor and Lemna gibba.

Science.gov (United States)

Iatrou, Evangelia I; Kora, Elianta; Stasinakis, Athanasios S

2018-03-09

The use of duckweed-based wastewater treatment systems for producing biomass with high crude protein and starch content was investigated in the current study. For this reason, three lab-scale systems were used; System 1 was planted with Lemna minor, System 2 with Lemna gibba and System 3 with the combination of the two duckweeds. The studied duckweeds were cultivated using secondary treated wastewater as substrate (Phase A), in the presence of excess NH 4 -N (Phase B) and using water with no nutrients (Phase C). All systems achieved average NH 4 -N removal higher that 90%. The specific duckweeds growth rates and the specific duckweeds growth rates normalized to the area ranged between 0.14 d -1 and 8.9 g m -2  d -1 (System 1) to 0.19 d -1 and 14.9 g m -2  d -1 (System 3). The addition of NH 4 -N resulted in a significant increase of biomass protein content, reaching 44.4% in System 3, 41.9% in System 2 and 39.4% in System 1. The transfer of biomass in water containing no nutrients resulted in the gradual increment of the starch content up to the end of the experiment. The highest starch content was achieved for the combination of the two duckweeds (46.1%), followed by L. gibba (44.9%) and L. minor (43.9%).

Bioremoval of cadmium by lemna minor in different aquatic conditions

Energy Technology Data Exchange (ETDEWEB)

Uysal, Yagmur [Dept. of Environmental Engineering, Kahramanmaras Sutcu Imam University, Kahramanmaras (Turkey); Taner, Fadime [Dept. of Environmental Engineering, Mersin University, Mersin (Turkey)

2010-04-15

This study was undertaken to determine the cadmium removal efficiency of Lemna minor when it was used for treatment of wastewater having different characteristics, i. e., pH, temperature and cadmium concentration. Plants were cultivated in different pH solutions (4.5-8.0) and temperatures (15-35 C) in the presence of cadmium (0.1-10.0 mg/L) for 168 h. The amount of biomass obtained in the study period, the concentrations of cadmium in the tissues and in the media and net uptake of cadmium by Lemna have been determined for each condition. The percentages of cadmium uptake (PMU) and bioconcentration factors (BCF) were also calculated. The highest accumulation was obtained for the highest cadmium concentration of 10.0 mg Cd/L as 11.668 mg Cd/g at pH 6.0, and as 38.650 mg Cd/g at 35 C and pH 5.0. The cadmium accumulation gradually increased with initial concentration of the medium, but the opposite trend was observed for the PMU. However, the maximum PMU was obtained as 52.2% in the solution with the lowest concentration of 0.1 mg Cd/L. A mathematical model was used to describe the cadmium uptake and the equation obtained was seen to fit the experimental data very well. (Abstract Copyright [2010], Wiley Periodicals, Inc.)

Lemna Minor Indicative of Phosphorus Pollution in Panlong River%盘龙江青萍的磷污染指示性研究

Institute of Scientific and Technical Information of China (English)

兰丹; 苏怀; 常玉兰; 李福姗; 张亚楠; 赵宏兵

2016-01-01

Objective] To study the lemna minor indicative of phosphorus pollution in Panlong River.[Methods] Laboratory cultivation and field survey were carried.[Results] In laboratory cultivation condition: lemna minor can grow normally in culture solution with phosphorus concentration of 0.1 mg/L to 15 mg/L.In field survey condition, the phosphorus concentration at each sampling point in Panlong River was 0.07 mg/L to 0.47 mg/L.Distribution of lemna minor: no distribution in upper reaches, slight distribution in middle reaches, more abun-dance in low reaches.[Conclusion] Lemma minor can indicate the water quality above grade II, and water with appearance of lemna minor in-dicates phosphorus pollution.%[目的]判断青萍是否可以作为盘龙江磷污染的指示性生物。[方法]以青萍作为研究对象，研究青萍对磷的耐受程度，分实验室培养和野外调查。[结果]实验室培养条件下，青萍可以在磷浓度0．1～15．0 mg／L的培养液中正常生长。野外调查盘龙江各采样点磷浓度（0．07～0．47 mg／L）的青萍分布情况：上游河段没有出现，中游河段有出现，下游河段多度增加。[结论]青萍至少可以指示2类水以上的水质，有青萍出现的水体已经受到磷污染。

Ciprofloxacin induces oxidative stress in duckweed (Lemna minor L.): Implications for energy metabolism and antibiotic-uptake ability.

Science.gov (United States)

Gomes, Marcelo Pedrosa; Gonçalves, Cíntia Almeida; de Brito, Júlio César Moreira; Souza, Amanda Miranda; da Silva Cruz, Fernanda Vieira; Bicalho, Elisa Monteze; Figueredo, Cleber Cunha; Garcia, Queila Souza

2017-04-15

We investigate the physiological responses and antibiotic-uptake capacity of Lemna minor exposed to ciprofloxacin. Ciprofloxacin (Cipro) induced toxic effects and hormesis in plants by significantly modifying photosynthesis and respiration pathways. A toxic effect was induced by a concentration ≥1.05mg ciprofloxacin l -1 while hormesis occurs at the lowest concentration studied (0.75mg ciprofloxacin l -1 ). By impairing normal electron flow in the respiratory electron transport chain, ciprofloxacin induces hydrogen peroxide (H 2 O 2 ) production. The ability of plants to cope with H 2 O 2 accumulation using antioxidant systems resulted in stimulation/deleterious effects to photosynthesis by Cipro. Cipro-induced oxidative stress was also associated with the ability of L. minor plants to uptake the antibiotic and, therefore, with plant-uptake capacity. Our results indicate that instead of being a photosystem II binding molecule, Cipro induces oxidative stress by targeting the mitochondrial ETC, which would explain the observed effects of the antibiotic on non-target eukaryotic organisms. The selection of plants species with a high capacity to tolerate oxidative stress may constitute a strategy to be used in Cipro-remediation programs. Copyright © 2017 Elsevier B.V. All rights reserved.

THE ROLE OF DUCKWEED (LEMNA MINOR L. IN SECONDARY CLARIFIER TANKS

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Engin Gürtekin

2008-01-01

Full Text Available In this study, the effects of duckweed (Lemna minor L. presence on the effluent water quality and settling characteristics in the secondary clarifier tank of a conventional biological treatment plant were investigated. For this purpose, the performances of the secondary clarifier with and without duckweed were compared. In the secondary clarifier tank with duckweed, COD, BOD5, ammonium and phosphate removal efficiencies were higher by 15, 25, 35 and 45%, respectively. SS concentration of effluent and values of sludge volume index (SVI were the same. The results showed that duckweed contributes to treatment efficiency of conventional biological treatment plant, which reduces the need of tertiary nutrients removal.

Inhibition of sulfate uptake by Lemna minor 1. during aeration with sublethal concentrations of SO/sub 2/

Energy Technology Data Exchange (ETDEWEB)

Schaerer, M; Brunold, C; Erismann, K H

1975-01-01

The sulfate uptake of Lemna minor l. is very rapidly inhibited by SO/sub 2/-concentrations of 0.15, 0.32 and 0.61 ppM. The sulfate concentration in the plant material is increased. At least 40% of the total sulfur in the organisms originate from SO/sub 2/.

Stress and Protein Turnover in Lemna minor1

Science.gov (United States)

Cooke, Robert J.; Oliver, Jane; Davies, David D.

1979-01-01

Transfer of fronds of Lemna minor L. to adverse growth conditions or stress situations causes a lowering of the growth rate and a loss of soluble protein per frond, the extent of the loss being dependent on the nature of the stress. The loss or protein is due to two factors: (a) a decrease in the rate constant of protein synthesis (ks); (b) an increase in the rate constant of protein degradation (kd). In plants adapted to the stresses, protein synthesis increases and the initially rapid rate of proteolysis is reduced. Addition of abscisic acid both lowers ks and increases kd, whereas benzyladenine seems to alleviate the effects of stress on protein content by decreasing kd rather than by altering ks. Based on the measurement of enzyme activities, stress-induced protein degradation appears to be a general phenomenon, affecting many soluble proteins. The adaptive significance of stress-induced proteolysis is discussed. PMID:16661102

The Phosphorylation of Ribosomal Protein in Lemna minor

Science.gov (United States)

Trewavas, A.

1973-01-01

Sterile cultures of Lemna minor have been labeled with 32P1, and the ribosomal proteins have been examined for radioactivity. In relatively short term labeling a radioactive protein was found which ran as a single component in both urea/acetic acid and sodium lauryl sulfate gel electrophoresis. Acid hydrolysis of the labeled protein permitted the isolation of serine phosphate. After labeling to equilibrium with 32P1, calculation indicated only 0.6 to 0.75 atom of this protein phosphorus per ribosome. The phosphorylated protein is found in both polysomes and “derived” monomers and appears to be located in the ribosomal small subunit. Its apparent molecular weight is 42,000. Addition of growth-inhibiting concentrations of abscisic acid does not alter the apparent degree of labeling of this protein in 5 hours, but after 24 hours of treatment the total protein phosphorus was reduced from 0.75 atom of phosphorus per ribosome to 0.36 atom of phosphorus per ribosome. PMID:16658405

Comparative sensitivity of Selenastrum capricornutum and Lemna minor to sixteen herbicides

Science.gov (United States)

Fairchild, J.F.; Ruessler, D.S.; Haverland, P.S.; Carlson, A.R.

1997-01-01

Aquatic plant toxicity tests are frequently conducted in environmental risk assessments to determine the potential impacts of contaminants on primary producers. An examination of published plant toxicity data demonstrates that wide differences in sensitivity can occur across phylogenetic groups of plants. Yet relatively few studies have been conducted with the specific intent to compare the relative sensitivity of various aquatic plant species to contaminants. We compared the relative sensitivity of the algae Selenestrum capricornutum and the floating vascular plant Lemna minor to 16 herbicides (atrazine, metribuzin, simazine, cyanazine, alachlor, metolachlor, chlorsulfuron, metsulfuron, triallate, EPTC, trifluralin, diquat, paraquat, dicamba, bromoxynil, and 2,4-D). The herbicides studied represented nine chemical classes and several modes of action and were chosen to represent major current uses in the United States. Both plant species were generally sensitive to the triazines (atrazine, metribuzin, simazine, and cyanazine), sulfonureas (metsulfuron and chlorsulfuron), pyridines (diquat and paraquat), dinitroaniline (trifluralin), and acetanilide (alachlor and metolachlor) herbicides. Neither plant species was uniformly more sensitive than the other across the broad range of herbicides tested. Lemna was more sensitive to the sulfonureas (metsulfuron and chlorsulfuron) and the pyridines (diquat and parequat) than Selenastrum. However Selenastrum was more sensitive than Lemna to one of two thiocarbamates (triallate) and one of the triazines (cyanazine). Neither species was sensitive to selective broadleaf herbicides including bromoxynil, EPTC, dicamba, or 2,4-D. Results were not always predictable in spite of obvious differences in herbicide modes of action and plant phylogeny. Major departures in sensitivity of Selenastrum occurred between chemicals within individual classes of the triazine, acetanilide, and thiocarbamate herbicides. Results indicate that neither

Response of Lemna minor L. to short-term cobalt exposure: The effect on photosynthetic electron transport chain and induction of oxidative damage.

Science.gov (United States)

Begović, Lidija; Mlinarić, Selma; Antunović Dunić, Jasenka; Katanić, Zorana; Lončarić, Zdenko; Lepeduš, Hrvoje; Cesar, Vera

2016-06-01

The effect of two concentrations of cobalt (Co(2+)) on photosynthetic activity and antioxidative response in Lemna minor L. were assessed 24, 48 and 72h after the start of the exposure. Higher concentration of cobalt (1mM) induced growth inhibition while lower concentration (0.01mM) increased photosynthetic pigments content. Analysis of chlorophyll a fluorescence transients revealed high sensitivity of photosystem II primary photochemistry to excess of Co(2+) especially at the higher concentration where decreased electron transport beyond primary quinone acceptor QA(-) and impaired function of oxygen evolving complex (OEC) was observed. Due to impairment of OEC, oxygen production was decreased at higher Co(2+) concentration. Activity of superoxide dismutase was mainly inhibited while lipid peroxidation increased, at both concentrations, indicating that cobalt-induced oxidative damage after short exposure and moreover, susceptibility of the membranes in the cell to cobalt toxicity. Results obtained in this study suggest possible application of used parameters as tools in assessment of early damage caused by metals. Copyright © 2016 Elsevier B.V. All rights reserved.

Effect of ionic interaction of chlorode-borate and iodide-borate on their absorption by Lemna minor L

Energy Technology Data Exchange (ETDEWEB)

Thellier, M; Ayadi, A; Tromeur, C

1967-11-27

The effect of borate ions on the absorption of chloride and iodide ions by Lemna minor was studied by using the radioactive tracers Cl-36 at 23/sup 0/C with an illumination of 8000 Lux and I-131 at 25.5 C with 600 Lux. The absorbed quantities of the tracer elements were measured with a Geiger counter. The concentrations of sodium chloride solutions tested ranged from 0.055 to 1 mM, those of potassium iodide from 0.04 to 4 mM. While the presence of borate ions in the test solutions of NaCl inhibited the absorption of Cl ions by Lemna minor, only a mild inhibition or none at all was noted in the case of the absorption of I ions. Because of the difference of the cations (sodium in the case of Cl, potassium in the case of I) no direct comparison can be drawn between the absorption of the two halogens. The absorption of I by the plant is thought to proceed by a much simpler mechanism than that of Cl.

Production of biogas from Azolla pinnata R. Br. and Lemna minor L. : effect of heavy metal contamination

Energy Technology Data Exchange (ETDEWEB)

Jain, S K; Gujral, G S; Jha, N K; Vasudevan, P [Indian Inst. of Tech., New Delhi (India)

1992-01-01

The absorption of iron, copper, cadmium, nickel, lead, zinc, manganese and cobalt by Azolla pinnata R.Br and Lemna minor L., and subsequent utilization of this biomass for production of biogas (methane), have been investigated. Iron or manganese did not have any toxic effect on the anaerobic fermentation of Azolla and Lemna, while copper, cobalt, lead and zinc showed toxicity. At low concentrations cadmium and nickel showed a favourable effect on the rate of biogas production and its methane content, but with increase in concentrations,rate of biogas production and methane content decreased. However, although there was this decrease in biogas production and methane content, the methane content of biogas was still higher than that which was obtained from non-contaminated biomass. (author).

Inhibition of phosphorylation and incorporation of thymidine in Duckweed (Lemna minor L. ) by sulfur dioxide and sulfite

Energy Technology Data Exchange (ETDEWEB)

Braendle, R; Stoeckli, B; Erismann, K H

1975-05-15

As there appears to be no thymidine kinase in duckweed (Lemna minor L.), thymidine seems to be phosphorylated by a nucleoside phosphotransferase. Phosphorylation and incorporation are inhibited by sulfur compounds such as sulfur dioxide and sulfite. The data are discussed in relation to the physiological effect of the air pollutant (SO2) on plant life. 12 references, 2 tables.

Temperature-dependent toxicity of artemisinin toward the macrophyte Lemna minor and the algae Pseudokirchneriella subcapitata

DEFF Research Database (Denmark)

Jessing, Karina Knudsmark; Andresen, Marianne; Cedergreen, Nina

2014-01-01

- and groundwater. To make better risk assessments of A. annua which is cultivated under varying climatic conditions, the temperature-dependent toxicity of artemisinin toward the green algae Pseudokirchneriella subcapitata and the macrophyte Lemna minor was evaluated at temperatures ranging from 10 to 30°C....... To include a possible effect of temperature on the degradation rate of artemisinin, artemisinin concentrations were measured during the experiment and toxicity was related to the time-weighted averages of exposure concentrations. The toxicity of artemisinin toward the macrophyte L. minor and the algae P....... subcapitata increased with increasing growth rates, and we conclude that bioavailability plays a minor role in the observed relation between temperature and toxicity of artemisinin. The obtained results are important for possible future risk assessment of A. annua cultivation....

ANALISIS PENGARUH VARIASI SUHU dan WAKTU PADA PROSES HIDROLISIS TERHADAP KADAR GLUKOSA DALAM PEMANFAATAN Lemna minor SEBAGAI BIOETANOL

Directory of Open Access Journals (Sweden)

Vivi Mayangsari

2014-10-01

Full Text Available Energi terbarukan sangatlah diperlukan karena semakin meluasnya krisis energi sehingga memerlukan alternatif selain penggunaan bahan bakar fosil, penggunaan bioethanol merupakan alternatif yang baik karena banyak kelebihanya. Lemna minor merupakan salah satu tumbuhan yang berpotensi sebagai bioethanol, hal ini dapat dilihat dari kandungan glukosanya yang tinggi. Tujuan penelitian ini adalah untuk mengetahui hubungan waktu dan suhu pada proses hidrolisis terhadap nilai kadar glukosa serta mengetahui hubungan densitas terhadap kadar etanol. Proses ekstrasi glukosa menggunakan perbandingan volume HCl dengan kosentrasi 0,1 N, berat serbuk Lemna minor dan volume aquades yaitu 1:10:100 dengan variasi waktu ekstrasi 60, 90, dan 120 menit pada variasi suhu 60, 70, 80 °C dengan ukuran serbuk 60 mesh. Hasil penelitian ekstrasi hidrolisis terbaik pada menit ke-90 didapatkan panjang gelombang tertinggi 415 nm. Semua glukosa pada ekstrasi 90 menit difermentasi menggunakan bakteri Saccharomiches cerevisiae sebanyak 10% dari volume glukosa dengan waktu 144 jam, setelah fermentasi selesai sampel didestilasi untuk menghilangkan kadar air dan dihasilkan kadar ethanol terbaik 0,47% dengan densitas 0,9345 gr/ml3pada panjang gelombang larutan glukosa 316 nm.

Enantioselective accumulation, metabolism and phytoremediation of lactofen by aquatic macrophyte Lemna minor.

Science.gov (United States)

Wang, Fang; Yi, Xiaotong; Qu, Han; Chen, Li; Liu, Donghui; Wang, Peng; Zhou, Zhiqiang

2017-09-01

Pesticides are frequently detected in water bodies due to the agricultural application, which may pose impacts on aquatic organisms. The enantioselective bioaccumulation and metabolism of the herbicide lactofen in aquatic floating macrophyte Lemna minor (L. minor) were studied and the potential L. minor phytoremediation was investigated. Ultra-high performance liquid chromatography - tandem mass spectrometry (UHPLC-MS-MS) analysis for lactofen and its two known metabolites in L. minor was performed. The initial concentrations of racemic lactofen, R-lactofen and S-lactofen were all 30μgL -1 in the growth solution. The distribution of lactofen and its metabolites in growth solution and L. minor was determined throughout a 5-d laboratory trial. It was observed that S-lactofen was preferentially taken up and metabolized in L. minor. After rac-lactofen exposure, the accumulation amount of S-lactofen was approximately 3-fold more than that of R-lactofen in L. minor and the metabolism rate of S-lactofen (T 1/2 =0.92 d) was significantly faster than R-lactofen (T 1/2 =1.55 d). L. minor could only slightly accelerate the metabolism and removal of lactofen in the growth solution. As for the metabolites, desethyl lactofen was found to be the major metabolite in L. minor and the growth solution, whereas the metabolite acifluorfene was undetectable. No interconversion of the two enantiomers was observed after individual enantiomer exposure, indicating they were configurationally stable. The findings of this work represented that the accumulation and metabolism of lactofen in L. minor were enantioselective, and L. minor had limited capacity for the removal of lactofen and its metabolite in water. Copyright © 2017. Published by Elsevier Inc.

The Application of Low-Cost Adsorbent for Reactive Blue 19 Dye Removal from Aqueous Solution: Lemna Minor

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Davoud Balarak

2015-10-01

Full Text Available Background & Aims of the Study: Due to widespread use and adverse effect of dyes, the removal of dyes from effluents is necessary. This study was aimed to remove the reactive blue 19 dye removal from aqueous solution by dried Lemna minor. Materials and Methods:  The effect of various parameters including contact time, solution pH, adsorbent dosage and dye concentration was investigated in this experimental-lab study, Also, the isotherm and kinetic studies was performed for RB19 dye adsorption process. Results: The results indicated that RB19 dye removal efficiency increases by increasing of contact time and adsorbent dosage. The equilibrium time was 75 min ad the maximum dye removal efficiency was obtained in pH=3. Also, the dye removal efficiency decreases by increasing of pH and initial concentration. It was found that the equilibrium data was best follow by Langmuier isotherm. Also, the pseudo-second-kinetic model was best applicable for RB 19 dye adsorption. Conclusion: It can be concluded that the dried Lemna minor can be considered as an effective adsorbent to remove the RB19 dye.

Insights into the structural and physicochemical properties of small granular starches from two hydrophyte duckweeds, Spirodela oligorrhiza and Lemna minor.

Science.gov (United States)

Chen, Lei; Yu, Changjiang; Ma, Yubin; Xu, Hua; Wang, Shumin; Wang, Yu; Liu, Xingxun; Zhou, Gongke

2016-11-29

The structure and physicochemical properties of starches from two hydrophyte duckweeds, Spirodela oligorrhiza and Lemna minor, were investigated and compared in this study. The amylose content and average size of starches were determined to be 20.85%, 4.70 μm and 27.77%, 6.17 μm for Spirodela oligorrhiza and Lemna minor, respectively. The average chain length of two duckweed starches was measured to be around DP 28. The chain length distribution was observed to be greatly different from other reported starches for the high proportion of long chains (DP ≥ 37) over 50%. Wide-angle X-ray diffraction profiles of the two starch samples displayed typical B-type diffraction pattern. The gelatinization enthalpy-changes (ΔH gel ) of two starch samples was about 10.40 J/g for two duckweed starches. The present results suggested the potential utilization of small granular starches from duckweed in functional foods and dietary supplement products. Copyright © 2016 Elsevier Ltd. All rights reserved.

Micro-scale elemental partition in tissues of the aquatic plant Lemna minor L. exposed to highway drainage water

International Nuclear Information System (INIS)

Mendes Godinho, R.; Raimundo, J.; Vale, C.; Anes, B.; Brito, P.; Alves, L.C.; Pinheiro, T.

2013-01-01

In the scope of a monitoring program to assess the environmental impact of automobile traffic over one main bridge in Lisbon, both water and duckweed (Lemna minor L.) were sampled from the road drainage tanks and analyzed for chemical elements. Plants uptake Cr, Mn, Cu, and Zn metals from rain water draining the bridge road. Nuclear microprobe elemental maps of cryosections of L. minor tissues showed that incorporated elements were internalized in fronds of the plant. This approach at micrometer level allows a better knowledge of the elemental tissue partitioning in this biomonitor organism

Micro-scale elemental partition in tissues of the aquatic plant Lemna minor L. exposed to highway drainage water

Science.gov (United States)

Mendes Godinho, R.; Raimundo, J.; Vale, C.; Anes, B.; Brito, P.; Alves, L. C.; Pinheiro, T.

2013-07-01

In the scope of a monitoring program to assess the environmental impact of automobile traffic over one main bridge in Lisbon, both water and duckweed (Lemna minor L.) were sampled from the road drainage tanks and analyzed for chemical elements. Plants uptake Cr, Mn, Cu, and Zn metals from rain water draining the bridge road. Nuclear microprobe elemental maps of cryosections of L. minor tissues showed that incorporated elements were internalized in fronds of the plant. This approach at micrometer level allows a better knowledge of the elemental tissue partitioning in this biomonitor organism.

Lemna minor L.: As bioindicator of heavy metal pollution in Skadar lake: Montenegro

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Kastratović Vlatko

2015-01-01

Full Text Available The use of aquatic plants to analyze the heavy metal pollution of a lake environment has a number of advantages over the standard chemical methods of the analysis of metal presence in water and sediment. The macrophyta Lemna minor L., sampled from Lake Skadar in Montenegro has been used as a bio-indicator. Floating macrophyte L. minor accumulates metals from water through its submerged roots and floated leaves. The contents of Cd, Cu, Co, Cr, Mn, Ni, Pb, Zn, Sr and V were determined in sediments, water and the plant. The results obtained indicated a very high capacity of L. minor for the accumulation of Mn. In addition, higher Zn concentration was found in root tissue comparing to the sediment. The concentration of the other metals under investigation decreases in the following order: sediment > L. minor(root > L. minor(leaf > water. Higher concentrations of all metals in the tissue of L. minor were observed at the end of the growing season. A higher metal content was recorded in the root compared to the leaf. In descending order, the concentrations in plant tissues were found for the following metals: Mn > Zn > Sr > Cu > Ni > Pb > Co > V > Cr > Cd, while the series of bioaccumulation is, in descending order: Mn > Zn > Ni > Co > Pb > Cu > Cr > V > Sr > Cd.

Mechanisms of EDDHA effects on the promotion of floral induction in the long-day plant Lemna minor (L.).

Science.gov (United States)

Krajncic, Bozidar; Nemec, Joze

2003-02-01

EDDHA added in an optimal concentration (20.5 mumol.L-1) to a modified Pirson-Seidel nutrient solution induces flowering in some clones of the species Lemna minor, Lemna gibba and Spirodela polyrrhiza, which in the absence of EDDHA in the same nutrient solution do not flower. By adding EDDHA (20.5 mumol.L-1), floral induction under LD conditions is optimally promoted in the long-day (LD) species Lemna minor. After adding EDDHA to the nutrient solution, before floral induction and during flowering, Zn, Mn and Cu content is significantly increased in plants. Zn-EDDHA (0.86 mumol.L-1), Mn-EDDHA (1.51 mumol.L-1) and Cu-EDDHA (0.12 mumol.L-1), when used individually, greatly promote flowering under LD conditions as compared to flowering in the same nutrient solution with an equivalent quantity of Zn, Mn or Cu in the nonchelate form. If, on the other hand, Zn-EDDHA and Mn-EDDHA are added to the nutrient solution together (instead of Zn and Mn in nonchelate form), their effect on the promotion of flowering is less than in the case of their individual use. This shows that there is antagonism between Zn-EDDHA and Mn-EDDHA that is eliminated by adding EDDHA to the nutrient solution. We obtained the highest percentage of flowering plants (i.e. 74%) if we added EDDHA (20.5 mumol.L-1) to the nutrient solution containing Mn, Zn and Cu in chelate form. 74% of flowering plants actually means that flowering was achieved in all physiologically mature plants. Our results show that EDDHA promotes floral induction in Lemna minor under LD conditions, especially through chelating Zn, Mn and Cu, and, in addition, through eliminating the antagonism between Mn and Zn chelates EDDHA. Zn-EDDHA (0.86 mumol.L-1) also promote floral differentiation, especially cell division of microspore mother cells into dyads and those into microspore tetrads, which can be seen in microphotographs. When investigating possible pathways through which Mn-EDDHA, Zn-EDDHA and Cu-EDDHA promote flowering, we studied

Isolation of Vibrio cholera El Tor Inaba From Lemna minor and Eichhornia crassipens Roots in Veracruz, Mexico

OpenAIRE

Cordoba Aguilar, Edgar; Herrera Rivero, Marisol; Rubi, Alberto; Arroyo-Helguera, Omar; Coutino Rodriguez, Rocio

2014-01-01

Background: During epidemic periods, the strain Vibrio cholera El Tor has been isolated from the aquatic macrophyte roots of Eichhornia crassipens and Lemna minor, suggesting that aquatic plants could be environmental reservoirs through either a non-specific association or a commensalism relationship. Therefore, it is important to understand V. cholera reservoirs in order to establish prevention strategies against this pathogen. Objectives: Our interest was to determine whether V. cholera cou...

GST(phi) gene from Macrophyte Lemna minor is involved in cadmium exposure responses

Institute of Scientific and Technical Information of China (English)

CHEN Shihua; CHEN Xin; DOU Weihong; WANG Liang; YIN Haibo; GUO Shanli

2016-01-01

Reactive oxygen species (ROS) scavengers,including ascorbate peroxidase,superoxide dismutase,catalase and peroxidase,are the most commonly used biomarkers in assessing an organisms' response to many biotic and abiotic stresses.In this study,we cloned an 866 bp GST(phi) gene in Lemna minor and investigated its characteristics,expression and enzymatic activities under 75 μmol/L cadmium concentrations in comparison with other ROS scavengers.GST(phi) gene expression patterns were similar to those of other scavengers of ROS.This suggests that GST(phi) might be involved in responding to heavy metal (cadmium) stress and that its expression level could be used as a bio-indicator in monitoring cadmium pollution.

GST ( phi) gene from Macrophyte Lemna minor is involved in cadmium exposure responses

Science.gov (United States)

Chen, Shihua; Chen, Xin; Dou, Weihong; Wang, Liang; Yin, Haibo; Guo, Shanli

2016-03-01

Reactive oxygen species (ROS) scavengers, including ascorbate peroxidase, superoxide dismutase, catalase and peroxidase, are the most commonly used biomarkers in assessing an organisms' response to many biotic and abiotic stresses. In this study, we cloned an 866 bp GST ( phi) gene in Lemna minor and investigated its characteristics, expression and enzymatic activities under 75 μmol/L cadmium concentrations in comparison with other ROS scavengers. GST ( phi) gene expression patterns were similar to those of other scavengers of ROS. This suggests that GST ( phi) might be involved in responding to heavy metal (cadmium) stress and that its expression level could be used as a bio-indicator in monitoring cadmium pollution.

Fate, toxicity and bioconcentration of cadmium on Pseudokirchneriella subcapitata and Lemna minor in mid-term single tests.

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Clément, Bernard; Lamonica, Dominique

2018-03-01

In the frame of a project which consists in modeling a laboratory microcosm under cadmium pressure, we initiated this study on the fate and effects of cadmium in the presence of either the microalga Pseudokirchneriella subcapitata or the duckweed Lemna minor, two organisms of the microcosm. For each organism, growth inhibition tests on a duration of 2-3 weeks were carried out with the objective of linking effects with total dissolved, ionic and internalized forms of cadmium. Numbers of organisms (algal cells or duckweed fronds) in 2-L beakers filled with synthetic nutritive medium containing EDTA were counted during the course of assays, while cadmium concentrations in the water and in the organisms were measured. Free cadmium fraction was calculated using PHREEQC, a computer program for chemical speciation. Results showed that cadmium toxicity to microalgae could be correlated to the free divalent fraction of this metal, limited by the presence of EDTA, and to its concentration in the organisms. Bioconcentration factors for our medium were suggested for P. subcapitata (111,000 on the basis of free cadmium concentration) and L. minor (17,812 on the basis of total dissolved concentration). No effect concentrations were roughly estimated around 400 µg/g for Pseudokirchneriella subcapitata and 200-300 µg/g for Lemna minor. This study is a first step towards a fate model based on chemical speciation for a better understanding of microcosm results.

The potential of Lemna gibba L. and Lemna minor L. to remove Cu, Pb, Zn, and As in gallery water in a mining area in Keban, Turkey.

Science.gov (United States)

Sasmaz, Merve; Arslan Topal, Emine Işıl; Obek, Erdal; Sasmaz, Ahmet

2015-11-01

This study was designed to investigate removal efficiencies of Cu, Pb, Zn, and As in gallery water in a mining area in Keban, Turkey by Lemna gibba L. and Lemna minor L. These plants were placed in the gallery water of Keban Pb-Zn ore deposits and adapted individually fed to the reactors. During the study period (8 days), the plant and water samples were collected daily and the temperature, pH, and electric conductivity of the gallery water were measured daily. The plants were washed, dried, and burned at 300 °C for 24 h in a drying oven. These ash and water samples were analyzed by ICP-MS to determine the amounts of Cu, Pb, Zn, and As. The Cu, Pb, Zn and As concentrations in the gallery water of the study area detected 67, 7.5, 7230, and 96 μg L(-1), respectively. According to the results, the obtained efficiencies in L. minor L. and L. gibba L. are: 87% at day 2 and 36% at day 3 for Cu; 1259% at day 2 and 1015% at day 2 for Pb; 628% at day 3 and 382% at day 3 for Zn; and 7070% at day 3 and 19,709% at day 2 for As, respectively. The present study revealed that both L. minor L. and L. gibba L. had very high potential to remove Cu, Pb, Zn, and As in gallery water contaminated by different ores. Crown Copyright © 2015. Published by Elsevier Ltd. All rights reserved.

Effects of high ammonium level on biomass accumulation of common duckweed Lemna minor L.

Science.gov (United States)

Wang, Wenguo; Yang, Chuang; Tang, Xiaoyu; Gu, Xinjiao; Zhu, Qili; Pan, Ke; Hu, Qichun; Ma, Danwei

2014-12-01

Growing common duckweed Lemna minor L. in diluted livestock wastewater is an alternative option for pollutants removal and consequently the accumulated duckweed biomass can be used for bioenergy production. However, the biomass accumulation can be inhibited by high level of ammonium (NH4 (+)) in non-diluted livestock wastewater and the mechanism of ammonium inhibition is not fully understood. In this study, the effect of high concentration of NH4 (+) on L. minor biomass accumulation was investigated using NH4 (+) as sole source of nitrogen (N). NH4 (+)-induced toxicity symptoms were observed when L. minor was exposed to high concentrations of ammonium nitrogen (NH4 (+)-N) after a 7-day cultivation. L. minor exposed to the NH4 (+)-N concentration of 840 mg l(-1) exhibited reduced relative growth rate, contents of carbon (C) and photosynthetic pigments, and C/N ratio. Ammonium irons were inhibitory to the synthesis of photosynthetic pigments and caused C/N imbalance in L. minor. These symptoms could further cause premature senescence of the fronds, and restrain their reproduction, growth and biomass accumulation. L. minor could grow at NH4 (+)-N concentrations of 7-84 mg l(-1) and the optimal NH4 (+)-N concentration was 28 mg l(-1).

Geomagnetic and strong static magnetic field effects on growth and chlorophyll a fluorescence in Lemna minor.

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Jan, Luka; Fefer, Dušan; Košmelj, Katarina; Gaberščik, Alenka; Jerman, Igor

2015-04-01

The geomagnetic field (GMF) varies over Earth's surface and changes over time, but it is generally not considered as a factor that could influence plant growth. The effects of reduced and enhanced GMFs and a strong static magnetic field on growth and chlorophyll a (Chl a) fluorescence of Lemna minor plants were investigated under controlled conditions. A standard 7 day test was conducted in extreme geomagnetic environments of 4 µT and 100 µT as well as in a strong static magnetic field environment of 150 mT. Specific growth rates as well as slow and fast Chl a fluorescence kinetics were measured after 7 days incubation. The results, compared to those of controls, showed that the reduced GMF significantly stimulated growth rate of the total frond area in the magnetically treated plants. However, the enhanced GMF pointed towards inhibition of growth rate in exposed plants in comparison to control, but the difference was not statistically significant. This trend was not observed in the case of treatments with strong static magnetic fields. Our measurements suggest that the efficiency of photosystem II is not affected by variations in GMF. In contrast, the strong static magnetic field seems to have the potential to increase initial Chl a fluorescence and energy dissipation in Lemna minor plants. © 2015 Wiley Periodicals, Inc.

Effects of gamma radiation in a wide range of doses on the morphological characteristics of Lemna minor L

International Nuclear Information System (INIS)

Rasskazova, M.M.; Berestina, A.V.

2011-01-01

The effects of gamma radiation on the morphological parameters of Lemna minor L. were studied. As the sensitive parameters were invited to use chlorosis and necrosis. Significant differences between samples begin to show after 14 days of observation. The presence of effect, irrespective of the dose in the range 0,1-30 Gy, shows the efficiency of a sufficiently small dose (0,1 Gy) was revealed.

Effects of CuO nanoparticles on Lemna minor.

Science.gov (United States)

Song, Guanling; Hou, Wenhua; Gao, Yuan; Wang, Yan; Lin, Lin; Zhang, Zhiwei; Niu, Qiang; Ma, Rulin; Mu, Lati; Wang, Haixia

2016-12-01

Copper dioxide nanoparticles (NPs), which is a kind of important and widely used metal oxide NP, eventually reaches a water body through wastewater and urban runoff. Ecotoxicological studies of this kind of NPs effects on hydrophyte are very limited at present. Lemna minor was exposed to media with different concentrations of CuO NPs, bulk CuO, and two times concentration of Cu 2+ released from CuO NPs in culture media. The changes in plant growth, chlorophyll content, antioxidant defense enzyme activities [i.e., peroxidase (POD), catalase (CAT), superoxide dismutase (SOD) activities], and malondialdehyde (MDA) content were measured in the present study. The particle size of CuO NPs and the zeta potential of CuO NPs and bulk CuO in the culture media were also analyzed to complementally evaluate their toxicity on duckweed. Results showed that CuO NPs inhibited the plant growth at lower concentration than bulk CuO. L. minor roots were easily broken in CuO NPs media under the experimental condition, and the inhibition occurred only partly because CuO NPs released Cu 2+ in the culture media. The POD, SOD, and CAT activities of L. minor increased when the plants were exposed to CuO NPs, bulk CuO NPs and two times the concentration of Cu 2+ released from CuO NPs in culture media, but the increase of these enzymes were the highest in CuO NPs media among the three kinds of materials. The MDA content was significantly increased compared with that of the control from 50 mg L -1 CuO NP concentration in culture media. CuO NPs has more toxicity on L. minor compared with that of bulk CuO, and the inhibition occurred only partly because released Cu 2+ in the culture media. The plant accumulated more reactive oxygen species in the CuO NP media than in the same concentration of bulk CuO. The plant cell encountered serious damage when the CuO NP concentration reached 50 mg L -1 in culture media. The toxicology of CuO NP on hydrophytes must be considered because that hydrophytes

Capacidad de las macrofitas Lemna minor y Eichhornia crassipes para eliminar el niquel

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BRES, P

2012-04-01

Full Text Available El objetivo de este trabajo fue estudiar la capacidad de dos especies de macrofitas, Lemna minor y Eichhornia crassipes, para eliminar el níquel. Se realizaron cuatro tratamientos durante dos semanas para cada una de las especies. Las plantas fueron incubadas con 0, 1, 3 y 6 mg l-1 de Ni. Ambas especies mostraron, en todos los tratamientos con Ni, una reducción en la concentración a lo largo del tiempo. L. minor mostró ser más eficiente para remover este ión a la más baja concentración. Sin embargo, en concentraciones más elevadas no se observaron diferencias entre ambas especies. El análisis del tejido de las plantas mostró que las mismas acumulaban el metal, en los tres casos evaluados con concentraciones diferentes.Palabras clave: fitorremediación, metales pesados, plantas acuáticas, acumulación.

Phytoremediation Potential of Duckweed (Lemna minor L.) On Steel Wastewater.

Science.gov (United States)

Saha, Priyanka; Banerjee, Angela; Sarkar, Supriya

2015-01-01

An eco-friendly and cost effective technique- phytoremediation was used to remediate contaminants from waste water. This study demonstrated that phytoremediation ability of duckweed (Lemna minor L.) to remove chloride, sulphate from Biological Oxygen Treatment (BOT) waste water of coke oven plant. The BOT water quality was assessed by analyzing physico-biochemical characters--pH, Biological oxygen demand (BOD), Chemical oxygen demand (COD), total dissolved solids (TDS) and elemental concentration. It was observed that an increase in pH value indicated an improvement of water quality. The experimental results showed that, duckweed effectively removed 30% chloride, 16% sulphate and 14% TDS from BOT waste water, which suggested its ability in phytoremediation for removal of chloride and sulphate from BOT waste water. A maximum increase of 30% relative growth rate of duckweed was achieved after 21 days of experiment. Thus, it was concluded that duckweed, an aquatic plant, can be considered for treatment of the effluent discharged from the coke oven plant.

A marriage of convenience; a simple food chain comprised of Lemna minor (L.) and Gammarus pulex (L.) to study the dietary transfer of zinc.

Science.gov (United States)

Lahive, E; O'Halloran, J; Jansen, M A K

2015-01-01

Macrophytes contribute significantly to the cycling of metals in aquatic systems, through accumulation during growth and release during herbivory or decomposition. Accumulation of high levels of metals has been extensively documented in Lemnaceae (duckweeds). However, the degree of trophic transfer of metals from Lemnaceae to secondary consumers remains poorly understood. This study demonstrates that zinc accumulated in Lemna minor is bioavailable to the herbivore consumer Gammarus pulex. Overall, the higher the zinc content of L. minor, the more zinc accumulated in G. pulex. Accumulation in G. pulex was such that mortality occurred when they were fed high zinc-containing L. minor. Yet, the percentage of consumed zinc retained by G. pulex actually decreased with higher zinc concentrations in L. minor. We hypothesise that this decrease reflects internal zinc metabolism, including a shift from soluble to covalently bound zinc in high zinc-containing L. minor. Consistently, relatively more zinc is lost through depuration when G. pulex is fed L. minor with high zinc content. The developed Lemna-Gammarus system is simple, easily manipulated, and sensitive enough for changes in plant zinc metabolism to be reflected in metal accumulation by the herbivore, and therefore suitable to study ecologically relevant metal cycling in aquatic ecosystems. © 2014 German Botanical Society and The Royal Botanical Society of the Netherlands.

Effects of heavy metals on ultrastructure and Hsp70 induction in Lemna minor L. exposed to water along the Sarno River, Italy.

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Basile, A; Sorbo, S; Cardi, M; Lentini, M; Castiglia, D; Cianciullo, P; Conte, B; Loppi, S; Esposito, S

2015-04-01

The effects of freshwater pollution in the highly contaminated river Sarno (Campania, Southern Italy) have been evaluated using bags containing the aquatic plant Lemna minor (Lemnacee, Arales), in order to determine morpho-physiological modifications as a response to pollutants. The exposition of Lemna bags for 7 days on three different sites along the river path showed alterations in chloroplasts and vacuoles shape and organization. Moreover, some specimens were exposed in vitro at the same heavy metal (HM) concentrations measured in the polluted sites of the river, and compared with data from the bag experiment; to verify the dose and time dependent effects, samples were exposed to HM in vitro at concentrations ranging from 10(-6) to 10(-4)M up to 7 days. Transmission electron microscopy (TEM) observations on in vitro plants confirmed that ultrastructural alterations affected most of plastids and the shape of different subcellular structures, namely vacuoles; in in vitro stressed specimens, Heat Shock Proteins 70 (Hsp70) levels changed, in dependence of changing levels of HM measured in different sites along the river path. Thus L. minor exhibited a possible correlation between the levels of HM pollution and Hsp70 occurrence; interestingly, the data presented showed that copper specifically increased Hsp70 levels at concentrations detected in polluted river waters, whereas cadmium and lead did not; on the other side, the latter represent highly toxic elements when specimens were exposed to higher levels in vitro. The effects of specific elements in vitro are compared to those observed in bags exposed along the river path; thus results are examined in order to propose L. minor as an organism able to be utilized to monitor heavy metals pollution; the possibility of using Hsp70s as specific markers of HM pollution is discussed. Copyright © 2015 Elsevier Inc. All rights reserved.

ANALISIS PENGARUH VARIASI PERSENTASE RAGI (Saccharomyces cerevisiae DAN WAKTU PADA PROSES FERMENTASI DALAM PEMANFAATAN DUCKWEED (Lemna minor SEBAGAI BIOETANOL

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Siti Khodijah

2015-04-01

Full Text Available Salah satu alternatif dalam mendukung ketersediaan sumber daya energi terbarukan adalah dengan memanfaatkan sumber dari non fosil seperti bioetanol. Bioetanol merupakan etanol yang dibuat dari biomass yang mengandung komponen pati (karbohidrat atau selulosa yang selanjutnya di fermentasi menggunakan bantuan mikroorganisme (Sacharomyces cerevisiae. Karbohidrat yang digunakan pada penelitian ini berasal dari Lemna minor (Duckweed. Penelitian ini bertujuan membuat bioetanol dari Lemna minor dengan variasi penambahan ragi dan lamanya waktu fermentasi terhadap nilai kadar etanol dan nilai densitas, serta mengetahui hubungan densitas dengan kadar etanol. Produksi bioetanol dari tanaman yang mengandung pati (karbohidrat, dilakukan melalui proses konversi karbohidrat menjadi gula (glukosa dengan hidrolisis asam (HCl, hidrolisat yang diperoleh selanjutnya dilakukan fermentasi dengan menambahkan yeast atau ragi sehingga diperoleh bioetanol. Variabel yang digunakan adalah perubahan massa ragi 5%,15%, dan 25% serta lama fermentasi 5, 6, dan 7 hari . Hasil penelitian menunjukkan lama fermentasi dan persentase ragi mempengaruhi kadar etanol. Nilai kadar etanol optimum diperoleh presentase ragi 25% dengan lama fermentasi 7 hari sebesar 3.81% dengan density optimum sebesar 0.9438 gr/cm3, Hubungan nilai densitas berbanding terbalik dengan peningkatan kadar etanol.

Phytotoxicity Studies of Metsulfuron-methyl, Terbuthylazine and 3, 5 -Dichlorophenol by Duckweed (Lemna minor L. Test

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M. Abbaspoor

2016-06-01

Full Text Available Introduction: From the floating aquatic plant species, duckweed (i.e., Lemna sp. is perhaps the most commonly used in toxicity testing. As its name implies, it is a staple in the summer diet of ducks as well as other aquatic organisms. Actually, “duckweed” can refer to both Lemna sp. and Spirodela sp. (greater duckweed, although, it is usually associated with Lemna minor. The Lemnaceae (duckweeds are cosmopolitan free-floating aquatic monocotyledonous angiosperms that commonly occur in fresh and brackish stagnant ponds and sluggish streams, mostly in tropical regions but also as far north as 60° and as far south as 40° latitude. Duckweeds are vascular floating non-rooted aquatic plants with a reduced root system and lack stems and true leaves. It has been speculated that the roots serve as anchors to keep the fronds right side up and to form the tangled masses, which are of some importance in dispersal and protection from water movement. They can reproduce both sexually and asexually, however, asexual vegetative reproduction is the more commonly occurring mode and, under laboratory conditions, a doubling in frond number and surface area covered can occur every 1.5–2 days. Duckweed can rapidly colonize open surface waters and develop a large biomass. These characteristics, plus its ability to accumulate inorganic ions favor it for use in wastewater treatment systems and makes duckweed an ideal model for studies on the metabolism of pollutants by aquatic macrophytes as well as for toxicity studies. They are very sensitive to many substances and are already used as convenient test organisms for toxicity evaluation of a number of pollutants including industrial and wastewater effluents, herbicides, heavy metals, surfactants and other common chemicals. The typical test end points are changes in the growth rate (expressed as frond production, fresh and dry weight and frond area and changes in pigment content. For a few years biotests with

De platte vorm van Lemna gibba, nog steeds een probleem

NARCIS (Netherlands)

Hartog, den C.

1968-01-01

A flat Lemna, obviously different from L. minor L., has been referred to as the flat form of L. gibba L. by DE LANGE & SEGAL (1968). L. gibba is able to produce flat fronds but this alone is insufficient evidence for the conclusion that the flat Lemna, so common in our waters, is only a pessimum

Uptake and toxicity of arsenic, copper, and silicon in Azolla caroliniana and Lemna minor.

Science.gov (United States)

Rofkar, Jordan R; Dwyer, Daryl F; Bobak, Deanna M

2014-01-01

Here we report on the analysis of two aquatic plant species, Azolla caroliniana and Lemna minor, with respect to tolerance and uptake of co-occurring arsenic, copper, and silicon for use in engineered wetlands. Plants were cultured in nutrient solution that was amended with arsenic (0 or 20 microM), copper (2 or 78 microM), and silicon (0 or 1.8 mM) either singly or in combination. We hypothesized that arsenic and copper would negatively affect the uptake of metals, growth, and pigmentation and that silicon would mitigate those stresses. Tolerance was assessed by measuring growth of biomass and concentrations of chlorophyll and anthocyanins. Both plant species accumulated arsenic, copper, and silicon; L. minor generally had higher levels on a per biomass basis. Arsenic negatively impacted A. caroliniana, causing a 30% decrease in biomass production and an increase in the concentration of anthocyanin. Copper negatively impacted L. minor, causing a 60% decrease in biomass production and a 45% decrease in chlorophyll content. Silicon augmented the impact of arsenic on biomass production in A. caroliniana but mitigated the effect of copper on L. minor. Our results suggest that mixtures of plant species may be needed to maximize uptake of multiple contaminants in engineered wetlands.

Comparison of different physiological parameter responses in Lemna minor and Scenedesmus obliquus exposed to herbicide flumioxazin

International Nuclear Information System (INIS)

Geoffroy, Laure; Frankart, Cecile; Eullaffroy, Philippe

2004-01-01

The sensitivity of different physiological parameters in Scenedesmus obliquus and Lemna minor exposed to herbicide (flumioxazin) was investigated to indicate the most convenient and sensitive parameter. To assess toxicity of flumioxazin, we used a panel of biomarkers: pigment contents, chlorophyll fluorescence parameters and antioxidative enzyme activities. Algae and duckweed were exposed to 48-h IC 50 for growth rate. In L. minor, the sensitivity of the parameters was as follows: Q N >Oxygen emission>PHIs PSII >Q P >PHI PSII >CAT, GR>Pigment>APO>Growth. For S. obliquus, this ranking was as follows: CAT>Oxygen emission>Q P >APO>GR>Pigment>PHIs PSII >Growth>PHI PSII >Q N (from the greatest to the least sensitive). The results demonstrated that the observed toxicity is related not only to interspecific variations but also to the selected parameter

Uranium and cadmium provoke different oxidative stress responses in Lemna minor L.

Science.gov (United States)

Horemans, N; Van Hees, M; Van Hoeck, A; Saenen, E; De Meutter, T; Nauts, R; Blust, R; Vandenhove, H

2015-01-01

Common duckweed (Lemna minor L.) is ideally suited to test the impact of metals on freshwater vascular plants. Literature on cadmium (Cd) and uranium (U) oxidative responses in L. minor are sparse or, for U, non-existent. It was hypothesised that both metals impose concentration-dependent oxidative stress and growth retardation on L. minor. Using a standardised 7-day growth inhibition test, the adverse impact of these metals on L. minor growth was confirmed, with EC50 values for Cd and U of 24.1 ± 2.8 and 29.5 ± 1.9 μm, respectively, and EC10 values of 1.5 ± 0.2 and 6.5 ± 0.9 μm, respectively. The metal-induced oxidative stress response was compared through assessing the activity of different antioxidative enzymes [catalase, glutathione reductase, superoxide dismutase (SOD), ascorbate peroxidase (APOD), guaiacol peroxidase (GPOD) and syringaldizyne peroxidase (SPOD)]. Significant changes in almost all antioxidative enzymes indicated their importance in counteracting the U- and Cd-imposed oxidative burden. However, some striking differences were also observed. For activity of APODs and SODs, a biphasic but opposite response at low Cd compared to U concentrations was found. In addition, Cd (0.5-20 μm) strongly enhanced plant GPOD activity, whereas U inhibited it. Finally, in contrast to Cd, U up to 10 μm increased the level of chlorophyll a and b and carotenoids. In conclusion, although U and Cd induce similar growth arrest in L. minor, the U-induced oxidative stress responses, studied here for the first time, differ greatly from those of Cd. © 2014 German Botanical Society and The Royal Botanical Society of the Netherlands.

Effects of fluorescent lighting on in vitro micropropagation of Lemna minor

Science.gov (United States)

Somsri, Kollawat; Pinyopich, Pataradawn; Mohammed, Waleed S.

2010-05-01

The vegetative in vitro propagation of Lemna minor stain SING-4 exposed to two different types of fluorescent light sources, Philips TLD 36W/54 and Toshiba FL40T8BRF/36, was studied. The liquid culture medium contained 4.43gl-1 phytohormone-free full-strength Murashige & Skoog (MS) basal medium with vitamins, 30gl-1 sucrose, and 1gl-1 MES. The results showed that both plant cultures had undergone normal asexual reproduction with an exponential increase trend. Cultures exposed to Toshiba FL40T8BRF/36 reproduced at a slightly faster rate while expressing significantly greener foliage (leaf color chart shade No.8), which indicates the presence of more chlorophyll, than cultures exposed to Philips TLD 36W/54 (leaf color chart shade No.4). The data obtained from our experiment reveals that light emitted from Toshiba FL40T8BRF/36 produces healthier and higher quality cultures.

Uptake of Cadmium by Lemna minor, a (hyper?- accumulator plant involved in phytoremediation applications

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Bianconi D.

2013-04-01

Full Text Available Metal pollution in waters and soils is a major environmental and human health problem. Cadmium (Cd2+ is a heavy metal displaying toxic effects in plants. In this work we studied the potentiality of Lemna minor, a monocotyledonous aquatic macrophyte, to phytoremediate cadmium-polluted waters. The plants were exposed to different cadmium concentrations 0, 13, 22 and 46μM CdSO4 for a period of 24, 48 and 72 hours. Relative growth rates (RGR, bioconcentration factor (BCF, tolerance index (Ti, cadmium uptake in whole plant and maximum efficiency of PSII (Fv/Fm were measured under controlled climate conditions. RGR, Ti and Fv/Fm declined with increasing exposure time and cadmium concentrations, while the BCF and cadmium uptake showed an opposite behavior. Data analysis of RGR, BCF, Tiand FV/FM indicates that L. minor maintains a good capacity of growth, metal bioconcentration, tolerance and efficiency of PSII up to 48h in plants exposed to 13 and 22μM CdSO4. Our results exhibited that L. minor is a good cadmium accumulator and is able to remediate Cd-polluted waters, especially at low Cd concentrations.

A Nanopore-Structured Nitrogen-Doped Biocarbon Electrocatalyst for Oxygen Reduction from Two-Step Carbonization of Lemna minor Biomass

Science.gov (United States)

Guo, Chaozhong; Li, Zhongbin; Niu, Lidan; Liao, Wenli; Sun, Lingtao; Wen, Bixia; Nie, Yunqing; Cheng, Jing; Chen, Changguo

2016-05-01

So far, the development of highly active and stable carbon-based electrocatalysts for oxygen reduction reaction (ORR) to replace commercial Pt/C catalyst is a hot topic. In this study, a new nanoporous nitrogen-doped carbon material was facilely designed by two-step pyrolysis of the renewable Lemna minor enriched in crude protein under a nitrogen atmosphere. Electrochemical measurements show that the onset potential for ORR on this carbon material is around 0.93 V (versus reversible hydrogen electrode), slightly lower than that on the Pt/C catalyst, but its cycling stability is higher compared to the Pt/C catalyst in an alkaline medium. Besides, the ORR at this catalyst approaches to a four-electron transfer pathway. The obtained ORR performance can be basically attributed to the formation of high contents of pyridinic and graphitic nitrogen atoms inside this catalyst. Thus, this work opens up the path in the ORR catalysis for the design of nitrogen-doped carbon materials utilizing aquatic plants as starting precursors.

Adjuvants affect duckweed (Lemna minor) control with pelargonic acid

Science.gov (United States)

Duckweeds (Lemna spp.) are small, free floating, aquatic plants that flourish on stagnant or slow-moving water surfaces throughout the world. Members of the genus are among the smallest flowering plants, providing food for fish and fowl, but their aggressive growth and invasive tendencies make them ...

Ecotoxicological assessments show sucralose and fluoxetine affect the aquatic plant, Lemna minor.

Science.gov (United States)

Amy-Sagers, Cherisse; Reinhardt, Keith; Larson, Danelle M

2017-04-01

Pharmaceuticals and personal care products (PPCP) are prevalent in aquatic systems, yet the fate and impacts on aquatic plants needs quantification for many compounds. We measured and detected sucralose (an artificial sweetener), fluoxetine (an antidepressant), and other PPCP in the Portneuf River in Idaho, USA, where Lemna minor (an aquatic plant in the environment and used in ecotoxicology studies) naturally occurs. Sucralose was hypothesized to negatively affect photosynthesis and growth of L. minor because sucralose is a chlorinated molecule that may be toxic or unusable for plant metabolism. A priori hypotheses were not created for fluoxetine due to lack of previous studies examining its impacts on plants. We conducted laboratory ecotoxicological assessments for a large range of concentrations of sucralose and fluoxetine on L. minor physiology and photosynthetic function. Frond green leaf area, root length, growth rate, photosynthetic capacity, and plant carbon isotopic composition (discrimination relative to a standard; δ 13 C) were measured among treatments ranging from 0 to 15000nmol/L-sucralose and 0-323nmol/L-fluoxetine. Contrary to our predictions, sucralose significantly increased green leaf area, photosynthetic capacity, and δ 13 C of L. minor at environmentally relevant concentrations. The increase of δ 13 C from sucralose amendments and an isotope-mixing model indicated substantial sucralose uptake and assimilation within the plant. Unlike humans who cannot break down and utilize sucralose, we documented that L. minor-a mixotrophic plant-can use sucralose as a sugar substitute to increase its green leaf area and photosynthetic capacity. Fluoxetine significantly decreased L. minor root growth, daily growth rate, and asexual reproduction at 323nmol/L-fluoxetine; however, ambiguity remains regarding the mechanisms responsible and the applicability of these extreme concentrations unprecedented in the natural environment. To our knowledge, this was the

Disposable electrochemical sensor to evaluate the phytoremediation of the aquatic plant Lemna minor L. toward Pb(2+) and/or Cd(2+).

Science.gov (United States)

Neagu, Daniela; Arduini, Fabiana; Quintana, Josefina Calvo; Di Cori, Patrizia; Forni, Cinzia; Moscone, Danila

2014-07-01

In this work a miniaturized and disposable electrochemical sensor was developed to evaluate the cadmium and lead ion phytoremediation potential by the floating aquatic macrophyte Lemna minor L. The sensor is based on a screen-printed electrode modified "in-situ" with bismuth film, which is more environmentally friendly than the mercury-based sensor usually adopted for lead and cadmium ion detection. The sensor was coupled with a portable potentiostat for the simultaneous measurement of cadmium and lead ions by stripping analysis. The optimized analytical system allows the simultaneous detection of both heavy metals at the ppb level (LOD equal to 0.3 and 2 ppb for lead and cadmium ions, respectively) with the advantage of using a miniaturized and cost-effective system. The sensor was then applied for the evaluation of Pb(2+) or/and Cd(2+) uptake by measuring the amount of the heavy metals both in growth medium and in plant tissues during 1 week experiments. In this way, the use of Lemna minor coupled with a portable electrochemical sensor allows the set up of a model system able both to remove the heavy metals and to measure "in-situ" the magnitude of heavy metal removal.

The Response of Lemna minor to Mixtures of Pesticides That Are Commonly Used in Thailand.

Science.gov (United States)

Tagun, Rungnapa; Boxall, Alistair B A

2018-04-01

In the field, aquatic organisms are exposed to multiple contaminants rather than to single compounds. It is therefore important to understand the toxic interactions of co-occurring substances in the environment. The aim of the study was to assess the effects of individual herbicides (atrazine, 2,4-D, alachlor and paraquat) that are commonly used in Thailand and their mixtures on Lemna minor. Plants were exposed to individual and binary mixtures for 7 days and the effects on plant growth rate were assesed based on frond area measurements. Experimental observations of mixture toxicity were compared with predictions based on single herbicide exposure data using concentration addition and independent action models. The single compound studies showed that paraquat and alachlor were most toxic to L. minor, followed by atrazine and then 2,4-D. For the mixtures, atrazine with 2,4-D appeared to act antagonistically, whereas alachlor and paraquat showed synergism.

Knopkroos (Lemna turionifera Landolt) nieuw voor Nederland

NARCIS (Netherlands)

Wolff, Peter; Bruinsma, John

2005-01-01

Lemna turionifera, een continentale en subatlatische soort, wordt sinds 1992 ook in Nederland waargenomen. Knopkroos kan worden onderscheiden van L. minor door zijn roodachtige kleur, de vorming van echte turionen, en door dunnere, kleinere, meer symmetrische schijfjes met een onopvallende apicale

Lead toxicity to Lemna minor predicted using a metal speciation chemistry approach.

Science.gov (United States)

Antunes, Paula M C; Kreager, Nancy J

2014-10-01

In the present study, predictive measures for Pb toxicity and Lemna minor were developed from bioassays with 7 surface waters having varied chemistries (0.5-12.5 mg/L dissolved organic carbon, pH of 5.4-8.3, and water hardness of 8-266 mg/L CaCO3 ). As expected based on water quality, 10%, 20%, and 50% inhibitory concentration (IC10, IC20, and IC50, respectively) values expressed as percent net root elongation (%NRE) varied widely (e.g., IC20s ranging from 306 nM to >6920 nM total dissolved Pb), with unbounded values limited by Pb solubility. In considering chemical speciation, %NRE variability was better explained when both Pb hydroxides and the free lead ion were defined as bioavailable (i.e., f{OH} ) and colloidal Fe(III)(OH)3 precipitates were permitted to form and sorb metals (using FeOx as the binding phase). Although cause and effect could not be established because of covariance with alkalinity (p = 0.08), water hardness correlated strongly (r(2)  = 0.998, p minor and highlight the importance of chemical speciation in Pb-based risk assessments for aquatic macrophytes. © 2014 SETAC.

Injury of Hg2+ and DBS on Lemna minor%Hg2+、DBS对浮萍的伤害研究

Institute of Scientific and Technical Information of China (English)

马剑敏; 王琳; 杜晋立; 吴晶敏

2001-01-01

The injury degree of Lemna minor by the stress of Hg2+ and DBSare reported.The concentrations of chlorophyll and dissolved protein decrease with the increase of Hg2+ and DBS concentrations or as treatment time is continued,dead percentage increase with the increase of Hg2+ and DBS concentrations or as treatment time is continued.When the concentrations of HgCl2 is 6mg/L or DBS is 12mg/L,about 70% of Lemna minor can live for 10 days at least.%研究了在Hg2+、DBS胁迫下，浮萍(LemnaminorL.)植株的枯死率、叶绿素含量和可溶性蛋白质含量的变化。植株的枯死率随Hg2+、DBS浓度升高和处理时间的延长而增加；叶绿素和蛋白质含量随Hg2+和DBS浓度升高和处理时间的延长而逐渐下降。在HgCl2、DBS浓度分别为6mg/L、12mg/L时，约70%的浮萍10d内仍存活。

Lemna minor tolerance to metal-working fluid residues: implications for rhizoremediation.

Science.gov (United States)

Grijalbo, L; Becerril, J M; Barrutia, O; Gutierrez-Mañero, J; Lucas Garcia, J A

2016-07-01

For the first time in the literature, duckweed (Lemna minor) tolerance (alone or in combination with a consortium of bacteria) to spent metal-working fluid (MWF) was assessed, together with its capacity to reduce the chemical oxygen demand (COD) of this residue. In a preliminary study, L. minor response to pre-treated MWF residue (ptMWF) and vacuum-distilled MWF water (MWFw) was tested. Plants were able to grow in both residues at different COD levels tested (up to 2300 mg·l(-1) ), showing few toxicity symptoms (mainly growth inhibition). Plant response to MWFw was more regular and dose responsive than when exposed to ptMWF. Moreover, COD reduction was less significant in ptMWF. Thus, based on these preliminary results, a second study was conducted using MWFw to test the effectiveness of inoculation with a bacterial consortium isolated from a membrane bioreactor fed with the same residue. After 5 days of exposure, COD in solutions containing inoculated plants was significantly lower than in non-inoculated ones. Moreover, inoculation reduced β+γ-tocopherol levels in MWFw-exposed plants, suggesting pollutant imposed stress was reduced. We therefore conclude from that L. minor is highly tolerant to spent MWF residues and that this species can be very useful, together with the appropriate bacterial consortium, in reducing COD of this residue under local legislation limits and thus minimise its potential environmental impact. Interestingly, the lipophilic antioxidant tocopherol (especially the sum of β+γ isomers) proved to be an effective plant biomarker of pollution. © 2016 German Botanical Society and The Royal Botanical Society of the Netherlands.

Comparison of different physiological parameter responses in Lemna minor and Scenedesmus obliquus exposed to herbicide flumioxazin

Energy Technology Data Exchange (ETDEWEB)

Geoffroy, Laure; Frankart, Cecile; Eullaffroy, Philippe

2004-09-01

The sensitivity of different physiological parameters in Scenedesmus obliquus and Lemna minor exposed to herbicide (flumioxazin) was investigated to indicate the most convenient and sensitive parameter. To assess toxicity of flumioxazin, we used a panel of biomarkers: pigment contents, chlorophyll fluorescence parameters and antioxidative enzyme activities. Algae and duckweed were exposed to 48-h IC{sub 50} for growth rate. In L. minor, the sensitivity of the parameters was as follows: Q{sub N}>Oxygen emission>PHIs{sub PSII}>Q{sub P}>PHI{sub PSII}>CAT, GR>Pigment>APO>Growth. For S. obliquus, this ranking was as follows: CAT>Oxygen emission>Q{sub P}>APO>GR>Pigment>PHIs{sub PSII}>Growth>PHI{sub PSII}>Q{sub N} (from the greatest to the least sensitive). The results demonstrated that the observed toxicity is related not only to interspecific variations but also to the selected parameter.

Linking mode of action of the model respiratory and photosynthesis uncoupler 3,5-dichlorophenol to adverse outcomes in Lemna minor.

Science.gov (United States)

Xie, Li; Gomes, Tânia; Solhaug, Knut Asbjørn; Song, You; Tollefsen, Knut Erik

2018-04-01

Standard chemical toxicity testing guidelines using aquatic plant Lemna minor have been developed by several international standardisation organisations. Although being highly useful for regulatory purposes by focusing on traditional adverse endpoints, these tests provide limited information about the toxic mechanisms and modes of action (MoA). The present study aimed to use selected functional assays in L. minor after exposure to 3,5-dichlorophenol (3,5-DCP) as a model to characterise the toxic mechanisms causing growth inhibition and lethality in primary producers. The results demonstrated that 3,5-DCP caused concentration-dependent effects in chloroplasts and mitochondria. Uncoupling of oxidative phosphorylation (OXPHOS), reduction in chlorophyll (Chlorophyll a and b) content, reproduction rate and frond size were the most sensitive endpoints, followed by formation of reactive oxygen species (ROS), lipid peroxidation (LPO), reduction of carotenoid content and impairment of photosynthesis efficiency. Suppression of photosystem II (PSII) efficiency, electron transport rate (ETR), chlorophyll (a and b) contents and oxidative phosphorylation (OXPHOS) were closely correlated while ROS production and LPO were negative correlated with ETR, carotenoid content and growth parameters. A network of conceptual Adverse Outcome Pathways (AOPs) was developed to decipher the causal relationships between molecular, cellular, and apical adverse effects occurring in L. minor to form a basis for future studies with similar compounds. Copyright © 2018 Elsevier B.V. All rights reserved.

Studies on the Growth Effects of the Canaline-Urea Cycle Amino Acids with Lemna minor L. 1

Science.gov (United States)

Rosenthal, Gerald A.; Gulati, Dushyant K.; Sabharwal, P. S.

1975-01-01

The aquatic microphyte, Lemna minor L., was utilized to assess the relative toxicity and general growth effects of canavanine, canaline, ureidohomoserine (UHS), and canavaninosuccinate (CSA). These amino acids are constituents of the canaline-urea cycle and structural analogues of the ornithine-urea cycle amino acids. Comparative growth studies with L. minor revealed that the canaline-urea cycle amino acids are potent antimetabolites. With the exception of CSA, they are extremely toxic at a concentration of 5 μm. Over a concentration range of 1 to 4 μm, canavanine is the most growth-inhibiting of the canaline-urea cycle amino acids. At or above 5 μm, canavanine and canaline possess comparable toxicity. UHS is less growth-inhibiting than canavanine or canaline, and CSA is the least toxic of the canaline-urea cycle intermediates. PMID:16659316

Phytotoxicity assessment of a methanolic coal dust extract in Lemna minor.

Science.gov (United States)

Coronado-Posada, Nadia; Cabarcas-Montalvo, Maria; Olivero-Verbel, Jesus

2013-09-01

Coal mining generates negative effects on environment, human health, hydrodynamics of mining areas and biodiversity. However, the impacts of this activity are less known in plants. Lemna minor is one of the most commonly used plants in aquatic toxicity tests due to its ubiquitous distribution in ponds and lakes, culture conditions and the free-floating habitat that exposes it to hydrophobic as well as dissolved compounds. The goal of this research was to evaluate the effects of a methanolic coal dust extract on L. minor. Macrophytes were exposed to six different concentrations of coal extract (from 7.81 to 250 mg/L) for 5 days, following the OECD test guideline 221. The coal extract had a half inhibitory concentration (IC50) of 99.66 (184.95-54.59) mg/L for the number of fronds. Several signs of toxicity such as chlorosis, reduction in the size of the fronds, abscission of fronds and roots, and the presence of necrotic tissues were observed at concentrations lower than the IC50. Preliminary Gas Chromatography-Mass Spectrometry analysis of the coal dust extract revealed the presence of several compounds, including, among others, alkanes, carboxylic acids and polycyclic aromatic hydrocarbons (PAHs), these lasts, may be responsible for some of the observed effects. These results demonstrated that coal dust has phytotoxic effects and should not be considered as an inert material. Copyright © 2013 Elsevier Inc. All rights reserved.

The first draft genome of the aquatic model plant Lemna minor opens the route for future stress physiology research and biotechnological applications

OpenAIRE

Van Hoeck, Arne; Horemans, Nele; Monsieurs, Pieter; Cao, Hieu Xuan; Vandenhove, Hildegarde; Blust, Ronny

2015-01-01

Background: Freshwater duckweed, comprising the smallest, fastest growing and simplest macrophytes has various applications in agriculture, phytoremediation and energy production. Lemna minor, the so-called common duckweed, is a model system of these aquatic plants for ecotoxicological bioassays, genetic transformation tools and industrial applications. Given the ecotoxic relevance and high potential for biomass production, whole-genome information of this cosmopolitan duckweed is needed. Res...

Plant growth-promoting bacterium Acinetobacter calcoaceticus P23 increases the chlorophyll content of the monocot Lemna minor (duckweed) and the dicot Lactuca sativa (lettuce).

Science.gov (United States)

Suzuki, Wakako; Sugawara, Masayuki; Miwa, Kyoko; Morikawa, Masaaki

2014-07-01

Acinetobacter calcoaceticus P23 is a plant growth-promoting bacterium that was isolated from the surface of duckweed (Lemna aoukikusa). The bacterium was observed to colonize on the plant surfaces and increase the chlorophyll content of not only the monocotyledon Lemna minor but also the dicotyledon Lactuca sativa in a hydroponic culture. This effect on the Lactuca sativa was significant in nutrient-poor (×1/100 dilution of H2 medium) and not nutrient-rich (×1 or ×1/10 dilutions of H2 medium) conditions. Strain P23 has the potential to play a part in the future development of fertilizers and energy-saving hydroponic agricultural technologies. Copyright © 2013 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

Potential of duckweed (Lemna minor) for removal of nitrogen and phosphorus from water under salt stress.

Science.gov (United States)

Liu, Chunguang; Dai, Zheng; Sun, Hongwen

2017-02-01

Duckweed plays a major role in the removal of nitrogen (N) and phosphorus (P) from water. To determine the effect of salt stress on the removal of N and P by duckweed, we cultured Lemna minor, a common species of duckweed, in N and P-rich water with NaCl concentrations ranging from 0 to 100 mM for 24 h and 72 h, respectively. The results show that the removal capacity of duckweed for N and P was reduced by salt stress. Higher salt stress with longer cultivation period exerts more injury to duckweed and greater inhibition of N and P removal. Severe salt stress (100 mM NaCl) induced duckweed to release N and P and even resulted in negative removal efficiencies. The results indicate that L. minor should be used to remove N and P from water with salinities below 75 mM NaCl, or equivalent salt stress. Copyright © 2016 Elsevier Ltd. All rights reserved.

Treatment of wastewater by lemna minor

International Nuclear Information System (INIS)

Iram, S.; Zahra, A.

2012-01-01

The aim of the present study was to study the performance of bio-treatment ponds after one year of functioning at National Agricultural Research Center, Islamabad, Pakistan. The physical parameters (colour, pH, EC, TDS, turbidity) and chemical parameters (Zn, Cu, Cd, Ni, Mn, Fe and Pb) are with in the limits which are not sub-lethal for fish rearing. Lemna accumulates higher concentration of heavy metals as compared to wastewater and best for phyto remediation purpose. The treated wastewater is currently used for rearing of fish and irrigation of crops and plants. The plants around the bio-treatment ponds are healthy, green and showing enough production. The present investigation indicates that in future it would be possible to construct bio-treatment ponds in polluted areas of Pakistan. (author)

Effects of a rhizobacterium on the growth of and chromium remediation by Lemna minor.

Science.gov (United States)

Tang, Jie; Zhang, Ying; Cui, Yan; Ma, Jiong

2015-07-01

Duckweed has shown great potential for both energy and environmental applications, particularly in wastewater treatment and fuel ethanol production. A rhizobacterium, Exiguobacterium sp. MH3, has been reported to associate with the duckweed Lemna minor for symbiotic growth. The aim of this work is to study the effects of rhizobacterium MH3 on L. minor growth and chromium (Cr) remediation. It appeared to have a synergism between the rhizobacterium MH3 and duckweed; the presence of strain MH3 promoted the growth of duckweeds by increasing both the frond number and dry weight of duckweed by more than 30%, while duckweed in turn provided essential carbon source and energy for the growth of rhizobacterium MH3. Under Cr(VI) exposure, particularly at higher Cr(VI) concentrations, Exiguobacterium sp. MH3 significantly alleviated the harmful effects of the stress on the duckweed by promoting duckweed growth and preventing duckweed from excessive uptake of Cr. Potential mechanisms were also discussed in light of the genome sequence of strain MH3, and it was speculated that siderophores and indole-3-acetic acid (IAA) secreted by strain MH3 might contribute to promoting duckweed growth.

Insights into phytase-containing transgenic Lemna minor (L.) as a novel feed additive.

Science.gov (United States)

Ghosh, Mrinmoy; Sharma, Neelesh; Gera, Meeta; Kim, Nameun; Huynh, Do; Zhang, Jiaojiao; Min, Taesun; Sodhi, Simrinder Singh; Kim, Min Bae; Rekha, V P B; Ko, Sukmin; Jeong, Dong Kee

2018-04-01

This study assessed the effect of supplementation of novel transgenic phytase on growth performance and bone mineralization in Korean native broiler chickens. The experiment was designed using four dietary groups: those with a diet supplemented with (A) recombinant phytase, (B) transgenic phytase from the plant Lemna minor, (C) or wild-type L. minor as well as (D) a control group that was supplemented with commercially available feed. Three hundred 1-day-old Korean native broiler chicks were used and divided into these four dietary treatment groups having three replicates of 25 birds each (n = 75). The results showed increases in growth performance and bone mineralization in Groups B and C; compared with Groups A and D. Hematological analyses revealed notable contrasts in erythrocyte sedimentation rate, red blood cell count, and hemoglobin levels among the experimental groups, whereas no impacts of dietary treatment were observed on total eosinophil, lymphocyte, heterophil, monocyte, and basophil levels. The relative expression profiling of candidate genes showed that the genes involved in growth response, meat quality, and P-Ca metabolism were significantly highly expressed in the phytase-supplemented groups. Hence, it is suggested that dietary supplementation with transgenic phytase plant L. minor for enhancing growth performance is a promising new approach in the broiler feed industry. To the best of our knowledge, we report here the most comprehensive analysis using a broiler model that provides a workable platform for further research on the cost-effective production of feed with different compositions that might be beneficial in the livestock feed industry.

Effect of Used Battery Lixivium on Growth of Lemna minor%废电池浸出液对青萍(Lemna minor)生长的影响

Institute of Scientific and Technical Information of China (English)

宋关玲; 马汇泉; 宋新华

2009-01-01

为了研究青萍(Lemna minor)是否可以应用于有废电池污染的富营养化地表水体的治理和生态修复中,用不同倍数稀释的废电池浸出液处理3d的青萍作为试验材料,研究了在短期培养条件下,废电池浸出液对青萍生长的影响,并测定了抗氧化系统的几种酶(POD、CAT、SOD)的活性以及可溶性蛋白质量分数的变化.研究表明:青萍对废电池浸出液很敏感,低质量浓度的废电池浸出液可以使青萍中活性氧的含量增高,高质量浓度的废电池浸出液可以使青萍抗氧化酶系统紊乱,该植物在有废电池污染的水体中应该慎重应用.

Correlations in metal release profiles following sorption by Lemna minor.

Science.gov (United States)

Üçüncü Tunca, Esra; Ölmez, Tolga T; Özkan, Alper D; Altındağ, Ahmet; Tunca, Evren; Tekinay, Turgay

2016-08-02

Following the rapid uptake of contaminants in the first few hours of exposure, plants typically attempt to cope with the toxic burden by releasing part of the sorbed material back into the environment. The present study investigates the general trends in the release profiles of different metal(loid)s in the aquatic macrophyte Lemna minor and details the correlations that exist between the release of metal(loid) species. Water samples with distinct contamination profiles were taken from Nilüfer River (Bursa, Turkey), Yeniçağa Lake (Bolu, Turkey), and Beyşehir Lake (Konya, Turkey) and used for release studies; 36 samples were tested in total. Accumulation and release profiles were monitored over five days for 11 metals and a metalloid ((208)Pb, (111)Cd, (52)Cr,(53)Cr,(60)Ni,(63)Cu,(65)Cu,(75)As,(55)Mn, (137)Ba, (27)Al, (57)Fe, (66)Zn,(68)Zn) and correlation, cluster and principal component analyses were employed to determine the factors that affect the release of these elements. Release profiles of the tested metal(loid)s were largely observed to be distinct; however, strong correlations have been observed between certain metal pairs (Cr/Ni, Cr/Cu, Zn/Ni) and principal component analysis was able to separate the metal(loid)s into three well-resolved groups based on their release.

Thorough removal of inorganic and organic mercury from aqueous solutions by adsorption on Lemna minor powder

Energy Technology Data Exchange (ETDEWEB)

Li Shunxing, E-mail: lishunxing@fjzs.edu.cn [Department of Chemistry, Zhangzhou Normal University, Zhangzhou 363000 (China); Fujian Province University Key Laboratory of Analytical Science, Zhangzhou Normal University, Zhangzhou (China); Zheng Fengying; Huang Yang [Department of Chemistry, Zhangzhou Normal University, Zhangzhou 363000 (China); Fujian Province University Key Laboratory of Analytical Science, Zhangzhou Normal University, Zhangzhou (China); Ni Jiancong [Department of Chemistry, Zhangzhou Normal University, Zhangzhou 363000 (China)

2011-02-15

The adsorption ability of duckweed (Lemna minor) powders for removing inorganic and organic mercury (methyl and ethyl mercury) has been studied using cold vapour atomic absorption spectrometry. The optimal adsorption conditions were: (a) the pH value of the solution 7.0 for inorganic and ethyl mercury, 9.0 for methyl mercury, and (b) equilibrium adsorption time 10, 20, and 40 min for inorganic mercury, methyl mercury, and ethyl mercury, respectively. After adsorption by L. minor powder for 40 min, when the initial concentrations of inorganic and organic mercury were under 12.0 {mu}g L{sup -1} and 50.0 {mu}g L{sup -1}, respectively, the residual concentrations of mercury could meet the criterion of drinking water (1.0 {mu}g L{sup -1}) and the permitted discharge limit of wastewater (10.0 {mu}g L{sup -1}) set by China and USEPA, respectively. Thorough removal of both inorganic and organic mercury from aqueous solutions was reported for the first time. The significant adsorption sites were C-O-P and phosphate groups by the surface electrostatic interactions with aqueous inorganic and organic mercury cations, and then the selective adsorption was resulted from the strong chelating interaction between amine groups and mercury on the surface of L. minor cells.

Thorough removal of inorganic and organic mercury from aqueous solutions by adsorption on Lemna minor powder

International Nuclear Information System (INIS)

Li Shunxing; Zheng Fengying; Huang Yang; Ni Jiancong

2011-01-01

The adsorption ability of duckweed (Lemna minor) powders for removing inorganic and organic mercury (methyl and ethyl mercury) has been studied using cold vapour atomic absorption spectrometry. The optimal adsorption conditions were: (a) the pH value of the solution 7.0 for inorganic and ethyl mercury, 9.0 for methyl mercury, and (b) equilibrium adsorption time 10, 20, and 40 min for inorganic mercury, methyl mercury, and ethyl mercury, respectively. After adsorption by L. minor powder for 40 min, when the initial concentrations of inorganic and organic mercury were under 12.0 μg L -1 and 50.0 μg L -1 , respectively, the residual concentrations of mercury could meet the criterion of drinking water (1.0 μg L -1 ) and the permitted discharge limit of wastewater (10.0 μg L -1 ) set by China and USEPA, respectively. Thorough removal of both inorganic and organic mercury from aqueous solutions was reported for the first time. The significant adsorption sites were C-O-P and phosphate groups by the surface electrostatic interactions with aqueous inorganic and organic mercury cations, and then the selective adsorption was resulted from the strong chelating interaction between amine groups and mercury on the surface of L. minor cells.

The toxicity of zinc oxide nanoparticles to Lemna minor (L.) is predominantly caused by dissolved Zn.

Science.gov (United States)

Chen, Xiaolin; O'Halloran, John; Jansen, Marcel A K

2016-05-01

Nano-ZnO particles have been reported to be toxic to many aquatic organisms, although it is debated whether this is caused by nanoparticles per sé, or rather dissolved Zn. This study investigated the role of dissolved Zn in nano-ZnO toxicity to Lemna minor. The technical approach was based on modulating nano-ZnO dissolution by either modifying the pH of the growth medium and/or surface coating of nano-ZnO, and measuring resulting impacts on L. minor growth and physiology. Results show rapid and total dissolution of nano-ZnO in the medium (pH 4.5). Quantitatively similar toxic effects were found when L. minor was exposed to nano-ZnO or the "dissolved Zn equivalent of dissolved nano-ZnO". The conclusion that nano-ZnO toxicity is primarily caused by dissolved Zn was further supported by the observation that phytotoxicity was absent on medium with higher pH-values (>7), where dissolution of nano-ZnO almost ceased. Similarly, the reduced toxicity of coated nano-ZnO, which displays a slower Zn dissolution, is also consistent with a major role for dissolved Zn in nano-ZnO toxicity. Copyright © 2016 Elsevier B.V. All rights reserved.

Expression of H5 hemagglutinin vaccine antigen in common duckweed (Lemna minor) protects against H5N1 high pathogenicity avian influenza virus challenge in immunized chickens.

Science.gov (United States)

Bertran, Kateri; Thomas, Colleen; Guo, Xuan; Bublot, Michel; Pritchard, Nikki; Regan, Jeffrey T; Cox, Kevin M; Gasdaska, John R; Dickey, Lynn F; Kapczynski, Darrell R; Swayne, David E

2015-07-09

A synthetic hemagglutinin (HA) gene from the highly pathogenic avian influenza (HPAI) virus A/chicken/Indonesia/7/2003 (H5N1) (Indo/03) was expressed in aquatic plant Lemna minor (rLemna-HA). In Experiment 1, efficacy of rLemna-HA was tested on birds immunized with 0.2μg or 2.3 μg HA and challenged with 10(6) mean chicken embryo infectious doses (EID50) of homologous virus strain. Both dosages of rLemna-HA conferred clinical protection and dramatically reduced viral shedding. Almost all the birds immunized with either dosage of rLemna-HA elicited HA antibody titers against Indo/03 antigen, suggesting an association between levels of anti-Indo/03 antibodies and protection. In Experiment 2, efficacy of rLemna-HA was tested on birds immunized with 0.9 μg or 2.2 μg HA and challenged with 10(6) EID50 of heterologous H5N1 virus strains A/chicken/Vietnam/NCVD-421/2010 (VN/10) or A/chicken/West Java/PWT-WIJ/2006 (PWT/06). Birds challenged with VN/10 exhibited 100% survival regardless of immunization dosage, while birds challenged with PWT/06 had 50% and 30% mortality at 0.9 μg HA and 2.2 μg HA, respectively. For each challenge virus, viral shedding titers from 2.2 μg HA vaccinated birds were significantly lower than those from 0.9μg HA vaccinated birds, and titers from both immunized groups were in turn significantly lower than those from sham vaccinated birds. Even if immunized birds elicited HA titers against the vaccine antigen Indo/03, only the groups challenged with VN/10 developed humoral immunity against the challenge antigen. None (rLemna-HA 0.9 μg HA) and 40% (rLemna-HA 2.2 μg HA) of the immunized birds challenged with PWT/06 elicited pre-challenge antibody titers, respectively. In conclusion, Lemna-expressed HA demonstrated complete protective immunity against homologous challenge and suboptimal protection against heterologous challenge, the latter being similar to results from inactivated whole virus vaccines. Transgenic duckweed-derived HA could be a

Transcriptomic and physiological analysis of common duckweed Lemna minor responses to NH4(+) toxicity.

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Wang, Wenguo; Li, Rui; Zhu, Qili; Tang, Xiaoyu; Zhao, Qi

2016-04-18

Plants can suffer ammonium (NH4 (+)) toxicity, particularly when NH4 (+) is supplied as the sole nitrogen source. However, our knowledge about the underlying mechanisms of NH4 (+) toxicity is still largely unknown. Lemna minor, a model duckweed species, can grow well in high NH4 (+) environment but to some extent can also suffer toxic effects. The transcriptomic and physiological analysis of L. minor responding to high NH4 (+) may provide us some interesting and useful information not only in toxic processes, but also in tolerance mechanisms. The L. minor cultured in the Hoagland solution were used as the control (NC), and in two NH4 (+) concentrations (NH4 (+) was the sole nitrogen source), 84 mg/L (A84) and 840 mg/L (A840) were used as stress treatments. The NH4 (+) toxicity could inhibit the growth of L. minor. Reactive oxygen species (ROS) and cell death were studied using stained fronds under toxic levels of NH4 (+). The malondialdehyde content and the activities of superoxide dismutase and peroxidase increased from NC to A840, rather than catalase and ascorbate peroxidase. A total of 6.62G nucleotides were generated from the three distinct libraries. A total of 14,207 differentially expressed genes (DEGs) among 70,728 unigenes were obtained. All the DEGs could be clustered into 7 profiles. Most DEGs were down-regulated under NH4 (+) toxicity. The genes required for lignin biosynthesis in phenylpropanoid biosynthesis pathway were up-regulated. ROS oxidative-related genes and programmed cell death (PCD)-related genes were also analyzed and indicated oxidative damage and PCD occurring under NH4 (+) toxicity. The first large transcriptome study in L. minor responses to NH4 (+) toxicity was reported in this work. NH4 (+) toxicity could induce ROS accumulation that causes oxidative damage and thus induce cell death in L. minor. The antioxidant enzyme system was activated under NH4 (+) toxicity for ROS scavenging. The phenylpropanoid pathway was stimulated under

Impact of polyethylene microbeads on the floating freshwater plant duckweed Lemna minor.

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Kalčíková, Gabriela; Žgajnar Gotvajn, Andreja; Kladnik, Aleš; Jemec, Anita

2017-11-01

Microplastics (MP), small plastic particles below 5 mm, have become one of the central concerns of environmental risk assessment. Microplastics are continuously being released into the aquatic environment either directly through consumer products or indirectly through fragmentation of larger plastic materials. The aim of our study was to investigate the effect of polyethylene microbeads from cosmetic products on duckweed (Lemna minor), a freshwater floating plant. The effects of microbeads from two exfoliating products on the specific leaf growth rate, the chlorophyll a and b content in the leaves, root number, root length and root cell viability were assessed. At the same time, water leachates from microbeads were also prepared to exclude the contribution of cosmetic ingredients on the measured impacts. Specific leaf growth rate and content of photosynthetic pigments in duckweed leaves were not affected by polyethylene microbeads, but these microbeads significantly affected the root growth by mechanical blocking. Sharp particles also reduced the viability of root cells, while the impact of microbeads with a smooth surface was neglected. It was concluded that microbeads from cosmetic products can also have negative impacts on floating plants in freshwater ecosystems. Copyright © 2017 Elsevier Ltd. All rights reserved.

Suitability of duckweed (Lemna minor as feed for fish in polyculture system

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M.Z.H. Talukdar

2012-06-01

Full Text Available In the present study, we conducted an experiment to evaluate the effects of duckweed (Lemna minor as feed on fish production in polyculture. The experiment had 2 treatments where in treatment 1 (T1 ponds were supplied with duckweed as feed and in treatment 2 (T2 ponds were kept as control (without supply of duckweed. Average survival rates in T1 and T2 were 90 and 89%, respectively. The specific growth rates (SGR were higher in T1. Calculated net production in T1 was 6.25 tons ha.-1 yr.-1 and in T2 was 2.84 tons ha.-1 yr.-1. The ranges of physico-chemical parameters analyzed were within the productive limit and more or less similar in all the ponds under both treatments during the experimental period. There were 24 genera of phytoplankton under 5 major groups and 10 genera of zooplankton under 3 major groups found in the experimental ponds. The net production in T1 was significantly higher than that of T2 indicated the use of duckweed as feed for fishes is economically sustainable in polyculture.

Effect of pH, temperature, and lead concentration on the bioremoval of lead from water using Lemna minor.

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Uysal, Yağmur; Taner, Fadime

2009-09-01

This study examined the ability of the aquatic plant Lemna minor (duckweed) to remove soluble lead under various laboratory conditions. In a batch process L. minor was exposed to different pH values (4.5-8.0) and temperature (15-35 degrees C) in presence of different lead concentrations (0.1-10.0 mg L(-1)) for 168 h. The amount of biomass obtained in the study period on a dry weight basis, the concentrations of lead in tissue and in medium and net uptake of lead by Lemna all have been determined in each condition. The percentages of lead uptake ratios (PMU) and bioconcentration factors (BCF) were also calculated for these conditions. Bioaccumulated lead concentrations and the PMU were obtained at lowest pH of 4.5, and at 30 degrees C. The highest accumulated lead concentration was found at pH 4.5 as 3.599 mg Pb g(-1) in 10.0 mg L(-1). It decreased to pH 6.0, but it did not change at pH 6.0-8.0 range. The maximum lead accumulation was obtained at 30 degrees C as 8.622 mg Pb g(-1) in 10 mg L(-1) at pH 5.0, and the minimum was at 15 degrees C as 0.291 mg g(-1) in 0.1 mg L(-1). Lead accumulation gradually increased with increasing lead in medium, but the opposite trend was observed for PMU. Lead accumulation increased up to 50 mg L(-1), but did not change significantly in the 50.0-100.0 mg L(-1) range. The lead uptake from water was modeled and the equation fit the experimental data very well

Antioxidative stress responses in the floating macrophyte Lemna minor L. with cylindrospermopsin exposure.

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Flores-Rojas, Nelida Cecilia; Esterhuizen-Londt, Maranda; Pflugmacher, Stephan

2015-12-01

Cylindrospermopsin toxicity and oxidative stress have been examined in aquatic animals, however, only a few studies with aquatic plants have been conducted focusing on the potential for bioaccumulation of cylindrospermopsin. The oxidative stress effects caused by cylindrospermopsin on macrophytes have not yet been specifically studied. The oxidative stress response of Lemna minor L. with exposure to cylindrospermopsin, was therefore tested in this study. The hydrogen peroxide concentration together with the activities of the antioxidant enzymes (catalase, peroxidase, glutathione reductase and glutathione S-transferase) were determined after 24h (hours) of exposure to varying concentrations (0.025, 0.25, 2.5 and 25μg/L) of cylindrospermopsin. Responses with longer exposure periods (48, 96, 168h) were tested only with exposure to 2.5 and 25μg/L cylindrospermopsin. Additionally, the content of the carotenoids was determined as a possible non-enzymatic antioxidant defence mechanism against cylindrospermopsin. The levels of hydrogen peroxide increased after 24h even at the lowest cylindrospermopsin exposure concentrations. Catalase showed the most representative antioxidant response observed after 24h and maintained its activity throughout the experiment. Catalase activity corresponded with the contents of hydrogen peroxide at 2.5 and 25μg/L cylindrospermopsin. The data suggest that glutathione S-transferase, glutathione reductase and the carotenoid content act together with catalase but are more sensitive to higher concentrations of cylindrospermopsin and after a longer exposure period (168h). The results indicate that cylindrospermopsin promotes oxidative stress in L. minor at concentrations of 2.5 and 25μg/L. However, L. minor has sufficient defence mechanisms in place against this cyanobacterial toxin. Even though L. minor exhibits the potential to managing and control cylindrospermopsin contamination in aquatic systems, further studies in tolerance limits to

Recovery of Lemna minor after exposure to sulfadimethoxine irradiated and non-irradiated in a solar simulator.

Science.gov (United States)

Drobniewska, Agata; Wójcik, Dorota; Kapłan, Monika; Adomas, Barbara; Piotrowicz-Cieślak, Agnieszka; Nałęcz-Jawecki, Grzegorz

2017-12-01

Sulfonamides are the second most widely used group of veterinary antibiotics which are often detected in the environment. They are eliminated from freshwaters mainly through photochemical degradation. The toxicity of sulfadimethoxine (SDM) was evaluated with the use of Lemna minor before and after 1- and 4-h irradiation in a SunTest CPS+ solar simulator. Eight endpoints consisting of: number and total area of fronds, fresh weight, chlorophylls a and b, carotenoids, activity of catalase and guaiacol peroxidase, and protein content were determined. The total frond area and chlorophyll b content were the most sensitive endpoints with EC50 of 478 and 554 μg  L -1 , respectively. The activity of guaiacol peroxidase and catalase increased at SDM concentrations higher than 125 and 500 μg  L -1 , respectively. The SDM photodegradation rate for first order kinetics and the half-life were 0.259 h -1 and 2.67  h, respectively. The results show that the toxicity of irradiated solutions was caused by SDM only, and the photoproducts appeared to be either non-toxic or much less toxic to L. minor than the parent compound. To study the recovery potential of L. minor, after 7 days exposure in SDM solutions, the plants were transferred to fresh medium and incubated for the next 7 days. L. minor has the ability to regenerate, but a 7-day recovery phase is not sufficient for it to return to an optimal physiological state.

Isolation of Vibrio cholera El Tor Inaba From Lemna minor and Eichhornia crassipens Roots in Veracruz, Mexico

Science.gov (United States)

Cordoba Aguilar, Edgar; Herrera Rivero, Marisol; Rubi, Alberto; Arroyo-Helguera, Omar; Coutino Rodriguez, Rocio

2014-01-01

Background: During epidemic periods, the strain Vibrio cholera El Tor has been isolated from the aquatic macrophyte roots of Eichhornia crassipens and Lemna minor, suggesting that aquatic plants could be environmental reservoirs through either a non-specific association or a commensalism relationship. Therefore, it is important to understand V. cholera reservoirs in order to establish prevention strategies against this pathogen. Objectives: Our interest was to determine whether V. cholera could be isolated and typified from L. minor and E. crassipens roots. Materials and Methods: From 2004 to 2005, plants were collected from various ecological niches and the roots were used to isolate V. cholera. Standard bacteriological, biochemical and serological tests were used for its typification. Results: In five out of the nine ecological niches explored, we collected either L. minor or E. crassipens, as these specimens cohabited only in two niches. V. cholera was isolated from both L. minor and E. crassipens roots. The isolated V. cholera showed the same biochemical characteristics as the pure V. cholera strain which was used as a control. The isolated V. cholera corresponded to V. cholera O1 El Tor Inaba, which is the same serotype related to the last outbreak in Mexico. Conclusions: For first time V. cholera El Tor Inaba has been isolated several years after the last emergence of cholera in Mexico. A viable and cultivable V. cholera strain, sourced from freshwater niches in E. crassipens and L. minor roots, suggests the importance of these plants as a permanent aquatic reservoir for these organisms. The monitoring of E. crassipens and L. minor is the responsibility of health institutions in order to evaluate the ongoing risks. PMID:25147681

Isolation of Vibrio cholera El Tor Inaba From Lemna minor and Eichhornia crassipens Roots in Veracruz, Mexico.

Science.gov (United States)

Cordoba Aguilar, Edgar; Herrera Rivero, Marisol; Rubi, Alberto; Arroyo-Helguera, Omar; Coutino Rodriguez, Rocio

2014-03-01

During epidemic periods, the strain Vibrio cholera El Tor has been isolated from the aquatic macrophyte roots of Eichhornia crassipens and Lemna minor, suggesting that aquatic plants could be environmental reservoirs through either a non-specific association or a commensalism relationship. Therefore, it is important to understand V. cholera reservoirs in order to establish prevention strategies against this pathogen. Our interest was to determine whether V. cholera could be isolated and typified from L. minor and E. crassipens roots. From 2004 to 2005, plants were collected from various ecological niches and the roots were used to isolate V. cholera. Standard bacteriological, biochemical and serological tests were used for its typification. In five out of the nine ecological niches explored, we collected either L. minor or E. crassipens, as these specimens cohabited only in two niches. V. cholera was isolated from both L. minor and E. crassipens roots. The isolated V. cholera showed the same biochemical characteristics as the pure V. cholera strain which was used as a control. The isolated V. cholera corresponded to V. cholera O1 El Tor Inaba, which is the same serotype related to the last outbreak in Mexico. For first time V. cholera El Tor Inaba has been isolated several years after the last emergence of cholera in Mexico. A viable and cultivable V. cholera strain, sourced from freshwater niches in E. crassipens and L. minor roots, suggests the importance of these plants as a permanent aquatic reservoir for these organisms. The monitoring of E. crassipens and L. minor is the responsibility of health institutions in order to evaluate the ongoing risks.

Effects of nutrient media on vegetative growth of Lemna minor and Landoltia punctata during in vitro and ex vitro cultivation

Directory of Open Access Journals (Sweden)

Chokchai Kittiwongwattana

2013-01-01

Full Text Available Lemnaceous plants, namely Lemna minor and Landoltia punctata, have been used in various types of biological research. The effects of Murashige and Skoog (MS and Hoagland media on vegetative growth rate of both species during in vitro and ex vitro cultivation were investigated. Under axenic conditions, frond proliferation of L. minor and Lan. punctata in Hoagland medium are 8 and 11.5% respectively faster than that in MS medium. Biomass production in Hoagland medium also increases 2.2-fold (L. minor and 1.4-fold (Lan. punctata compared to MS medium. The roots of both species in MS medium are distinctly shorter than those in Hoagland medium. In contrast, ex vitro regeneration of frond colonies in MS medium is 22.2% (for L. minor and 17.1% (for Lan. punctata faster than in Hoagland medium. Similarly, ex vitro biomass production of both species in MS increases 1.8-fold (for L. minor and 1.3-fold (for Lan. punctata compared to that in Hoagland medium. Root elongation of the frond colonies in MS and Hoagland media is comparable. The distinct effects of MS and Hoagland media on vegetative growth of both species and the pre-determination of ex vitro growth rates in each medium are demonstrated.

Genetic programming-based mathematical modeling of influence of weather parameters in BOD5 removal by Lemna minor.

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Chandrasekaran, Sivapragasam; Sankararajan, Vanitha; Neelakandhan, Nampoothiri; Ram Kumar, Mahalakshmi

2017-11-04

This study, through extensive experiments and mathematical modeling, reveals that other than retention time and wastewater temperature (T w ), atmospheric parameters also play important role in the effective functioning of aquatic macrophyte-based treatment system. Duckweed species Lemna minor is considered in this study. It is observed that the combined effect of atmospheric temperature (T atm ), wind speed (U w ), and relative humidity (RH) can be reflected through one parameter, namely the "apparent temperature" (T a ). A total of eight different models are considered based on the combination of input parameters and the best mathematical model is arrived at which is validated through a new experimental set-up outside the modeling period. The validation results are highly encouraging. Genetic programming (GP)-based models are found to reveal deeper understandings of the wetland process.

Effect of graphene oxide on copper stress in Lemna minor L.: evaluating growth, biochemical responses, and nutrient uptake.

Science.gov (United States)

Hu, Changwei; Liu, Lei; Li, Xiuling; Xu, Yundi; Ge, Zhigang; Zhao, Yongjun

2018-01-05

The wide application and unique properties of graphene oxide (GO) make it to interact with other pollutants and subsequently alter their behavior and toxicity. We evaluated the influences of GO at different concentrations (1 and 5mg/L) on copper (Cu) stress in duckweed (Lemna minor L.) GO below a concentration of 5mg/L showed no adverse effects on L. minor. The addition of Cu above 10μM represented a stress condition, which was evidenced by various parameters such as frond number, percent inhibition of growth rate (I r ), total chlorophyll content, dry weight, superoxide dismutase (SOD), catalase (CAT), and peroxidase (POD). When L. minor was simultaneously exposed to GO and Cu, especially at a GO concentration of 5mg/L and a Cu level above 10μM, the increase of I r and decrease of chlorophyll content were inhibited, suggesting that the Cu stress was diminished in the presence of GO. The addition of Cu alone, ranging between 5 and 20μM, increased Cu, B, Mn, Fe, Co, and Zn uptake, but decreased P uptake. Our results suggest that GO can lessen Cu stress in L. minor via Cu adsorption, thereby protecting the plants from the damaging effects of high Cu concentrations. Copyright © 2017 Elsevier B.V. All rights reserved.

Toxic Effects of KBr on Lemna Minor%KBr对青萍的毒性效应

Institute of Scientific and Technical Information of China (English)

张萍; 李青竹; 李亚琪; 赵熙宇; 崔萍; 王仁君

2017-01-01

在实验室条件下,为了解溴化钾(KBr)对高等水生植物的毒性效应,以青萍(Lemna minorL.)为研究对象,采用连续式培养法进行培养,从生长、光合和抗氧化方面系统研究了不同浓度的KBr对青萍的毒性效应.实验结果表明:在0-20 μg/L溴化钾的处理下,与对照组相比,青萍的生长和生理生化指标并没有显著变化(P＞0.05),这说明KBr对青萍几乎没有毒害作用.上述实验结果为研究KBr对水生高等植物的毒性效应提供了理论支撑.

Fabrication and characterization of mesoporous activated carbon from Lemna minor using one-step H3PO4 activation for Pb(II) removal

International Nuclear Information System (INIS)

Huang, Yang; Li, Shunxing; Lin, Haibin; Chen, Jianhua

2014-01-01

Graphical abstract: - Highlights: • Activated carbon was prepared from Lemna minor using H 3 PO 4 activation. • Materials have higher mesoporosity (92.2%) and more oxygen and nitrogen-containing functional groups. • Materials can remove Pb(II) rapidly with monolayer adsorption capacity (170.9 mg/g). • The adsorption process fitted to Langmuir isotherm and pseudo-first-order kinetic. • Materials could be used as an economical, efficient adsorbent to remove Pb(II) ions. - Abstract: A low cost and locally available material, Lemna minor, was used to fabricate activated carbon using H 3 PO 4 activation. After H 3 PO 4 activation, the L. minor activated carbons (LACs) possess high mesoporosity (92.2%) and a surface area of 531.9 m 2 /g according to Brunauer–Emmett–Teller (BET) analysis. Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectrometer (XPS) analyses reveal the presence of rich hydroxyl, carboxyl, amide and phosphate functional groups on the LACs surface, leading to facile Pb(II) binding to the surface through strong chemisorptive bonds or ion-exchange. The kinetic and equilibrium data were well described by pseudo-first-order model and Langmuir isotherm, with the maximum monolayer adsorption capacity (q m ) 170.9 mg/g at 25 °C. The intra-particle diffusion mechanism was partially responsible for the adsorption. The adsorption process was spontaneous and endothermic with negative ΔG and positive ΔH. The Pb(II)-loaded LACs could be easily regenerated using 0.1-M HCl and reused for seven cycles without significant adsorption capacity reduction. The maximum percentage removal rate for Pb(II) (20 mg/L) was found to be 91.8% within 30 min, at optimum conditions of pH 6.0 and 25 °C. These suggested that the low-cost LACs could be used as a potential adsorbent in the treatment of lead-contaminated water

Catalytic production of levulinic acid and ethyl levulinate from uniconazole-induced duckweed (Lemna minor).

Science.gov (United States)

Liu, Chunguang; Feng, Qingna; Yang, Jirui; Qi, Xinhua

2018-05-01

Duckweed (Lemna minor) with a high starch content of 50.4% was cultivated by uniconazole-induction method. The cultivated duckweed was used to produce value-added chemicals such as glucose, levulinic acid and formic acid in diluted HCl aqueous solution. A high glucose yield of 93.4% (471 g/kg based on loading duckweed mass) could be achieved at 180 °C in short reaction time, and the generated glucose was converted into levulinic acid and formic acid with yields of 52.0% and 34.1%, respectively, for 150 min, corresponding to 262 g/kg levulinic acid yield and 171 g/kg formic acid yield based on the mass of loading duckweed, respectively. Moreover, the duckweed was efficiently converted to ethyl levulinate with 55.2% yield (400.6 g/kg) at 200 °C in ethanol. This work provides a promising strategy for the production of value-added chemicals from phytoplankton that is able to purify the wastewater containing high content of P and N. Copyright © 2018 Elsevier Ltd. All rights reserved.

Oxidative stress in duckweed (Lemna minor L.) caused by short-term cadmium exposure

Energy Technology Data Exchange (ETDEWEB)

Razinger, Jaka [Department for Environmental Technologies and Biomonitoring, Institute of Physical Biology, Veliko Mlacevo 59, SI-1290 Grosuplje (Slovenia)], E-mail: jaka@ifb.si; Dermastia, Marina [National Institute of Biology, Vecna pot 111, p.p. 141, SI-1001 Ljubljana (Slovenia); Biotechnical Faculty, Department of Biology, University of Ljubljana, Vecna pot 111, SI-1000 Ljubljana (Slovenia); Koce, Jasna Dolenc [Biotechnical Faculty, Department of Biology, University of Ljubljana, Vecna pot 111, SI-1000 Ljubljana (Slovenia); Zrimec, Alexis [Department for Environmental Technologies and Biomonitoring, Institute of Physical Biology, Veliko Mlacevo 59, SI-1290 Grosuplje (Slovenia)

2008-06-15

The mechanisms of plant defence against cadmium toxicity have been studied by short-term exposure of Lemna minor L. (common duckweed) to concentrations of CdCl{sub 2} ranging from 0 to 500 {mu}M. High accumulation of cadmium was observed (12,320 {+-} 2155 {mu}g g{sup -1} at 500 {mu}M CdCl{sub 2}), which caused a gradual decrease of plant growth, increased lipid peroxidation, and weakened the entire antioxidative defence. Total glutathione concentration decreased significantly; however, the concentration of oxidized glutathione remained stable. The responses of four antioxidant enzymes showed that catalase was the most inhibited after CdCl{sub 2} exposure, ascorbate peroxidase and guaiacol peroxidase moderately, and glutathione reductase least. The total antioxidative potential revealed an induced antioxidative network at 0.1 {mu}M CdCl{sub 2} (137 {+-} 13.2% of the control) and its reduction to only 47.4 {+-} 4.0% of the control at higher cadmium concentrations. The possible application of the examined biomarkers in ecotoxicological research is discussed. - The increase of total antioxidative potential at low cadmium concentration is one of the mechanisms that helps duckweed to cope with cadmium-induced oxidative stress.

Oxidative stress in duckweed (Lemna minor L.) caused by short-term cadmium exposure

International Nuclear Information System (INIS)

Razinger, Jaka; Dermastia, Marina; Koce, Jasna Dolenc; Zrimec, Alexis

2008-01-01

The mechanisms of plant defence against cadmium toxicity have been studied by short-term exposure of Lemna minor L. (common duckweed) to concentrations of CdCl 2 ranging from 0 to 500 μM. High accumulation of cadmium was observed (12,320 ± 2155 μg g -1 at 500 μM CdCl 2 ), which caused a gradual decrease of plant growth, increased lipid peroxidation, and weakened the entire antioxidative defence. Total glutathione concentration decreased significantly; however, the concentration of oxidized glutathione remained stable. The responses of four antioxidant enzymes showed that catalase was the most inhibited after CdCl 2 exposure, ascorbate peroxidase and guaiacol peroxidase moderately, and glutathione reductase least. The total antioxidative potential revealed an induced antioxidative network at 0.1 μM CdCl 2 (137 ± 13.2% of the control) and its reduction to only 47.4 ± 4.0% of the control at higher cadmium concentrations. The possible application of the examined biomarkers in ecotoxicological research is discussed. - The increase of total antioxidative potential at low cadmium concentration is one of the mechanisms that helps duckweed to cope with cadmium-induced oxidative stress

Evaluation of environmental bacterial communities as a factor affecting the growth of duckweed Lemna minor.

Science.gov (United States)

Ishizawa, Hidehiro; Kuroda, Masashi; Morikawa, Masaaki; Ike, Michihiko

2017-01-01

Duckweed (family Lemnaceae ) has recently been recognized as an ideal biomass feedstock for biofuel production due to its rapid growth and high starch content, which inspired interest in improving their productivity. Since microbes that co-exist with plants are known to have significant effects on their growth according to the previous studies for terrestrial plants, this study has attempted to understand the plant-microbial interactions of a duckweed, Lemna minor , focusing on the growth promotion/inhibition effects so as to assess the possibility of accelerated duckweed production by modifying co-existing bacterial community. Co-cultivation of aseptic L. minor and bacterial communities collected from various aquatic environments resulted in changes in duckweed growth ranging from -24 to +14% compared to aseptic control. A number of bacterial strains were isolated from both growth-promoting and growth-inhibitory communities, and examined for their co-existing effects on duckweed growth. Irrespective of the source, each strain showed promotive, inhibitory, or neutral effects when individually co-cultured with L. minor . To further analyze the interactions among these bacterial strains in a community, binary combinations of promotive and inhibitory strains were co-cultured with aseptic L. minor , resulting in that combinations of promotive-promotive or inhibitory-inhibitory strains generally showed effects similar to those of individual strains. However, combinations of promotive-inhibitory strains tended to show inhibitory effects while only Aquitalea magnusonii H3 exerted its plant growth-promoting effect in all combinations tested. Significant change in biomass production was observed when duckweed was co-cultivated with environmental bacterial communities. Promotive, neutral, and inhibitory bacteria in the community would synergistically determine the effects. The results indicate the possibility of improving duckweed biomass production via regulation of co

Onderzoek naar een geschikte combinatie toetsmethoden ter bepaling van de aquatische toxiciteit van milieugevaarlijke stoffen. Bijl.2: Onderzoek naar de bruikbaarheid van Lemna minor (eendekroos) voor routine toxiciteitsonderzoek en vergelijking van deze waterplant met eencellige groenalgen

NARCIS (Netherlands)

Adema DMM; de Zwart D

1984-01-01

Als aanvulling op het project "Onderzoek naar een geschikte combinatie toetsmethoden ter bepaling van de aquatische toxiciteit van milieugevaarlijke stoffen" werd vergelijkend onderzoek verricht naar de bruikbaarheid en gevoeligheid van eendekroos (Lemna minor) als toetsorganisme. Deze

Wood ash residue causes a mixture of growth promotion and toxicity in Lemna minor.

Science.gov (United States)

Jagodzinski, Lucas S; O'Donoghue, Marian T; Heffernan, Liam B; van Pelt, Frank N A M; O'Halloran, John; Jansen, Marcel A K

2018-06-01

The use of wood as a sustainable biofuel results in the generation of residual wood ash. The ash contains high amounts of plant macronutrients such as phosphorus, potassium, calcium as well as several micronutrients. To explore the potential use of wood ash as a fertiliser, the growth enhancing properties of Sitka spruce (Picea sitchensis Bong.) wood ash were contrasted with the potential toxic action, using common duckweed (Lemna minor L.) as a model test species. The growth of L. minor exposed to wood bottom and fly ash solids and corresponding leachates was assessed in ultra-oligotrophic and eutrophic media. Ash solids and leachates were also tested as neutralized preparations. Suspended ash solids promoted L. minor growth up to concentrations of 2.5-5g/L. Leachates promoted growth up to 10g ash equivalents per litre, but for bottom ash only. Beneficial effects of wood ash were most pronounced on ultra-oligotrophic medium. However, on such nutrient-deficient medium severe inhibition of L. minor biomass and frond growth was observed at relatively low concentrations of fly ash (EC 50 =14g/L). On standard, eutrophic medium, higher concentrations of fly ash (EC 50 =21g/L), or neutralized fly ash (EC 50 =37g/L) were required to impede growth. Bottom ash, or neutralized bottom ash retarded growth at concentrations of 51g/L and 74g/L (EC 50 ), respectively, in eutrophic medium. It appears that phytotoxicity is due to the elemental composition of the ash, its alkaline character, and possible interactions between these two properties. Growth promotion was due to the substantial content of plant nutrients. This study underlines the importance of the receiving environment (nutrient status and pH) in determining the balance between toxicity and growth promotion, and shows that the margin between growth promoting and toxicity inducing concentrations can be enlarged through ash neutralization. Copyright © 2017 Elsevier B.V. All rights reserved.

Preliminary assessment of heavy metals in water, sediment and macrophyte ( Lemna minor) collected from Anchar Lake, Kashmir, India

Science.gov (United States)

Showqi, Irfana; Lone, Farooq Ahmad; Naikoo, Mehrajuddin

2018-06-01

Water samples, sediments and free floating macrophytic plant, Lemna minor specimens were collected from five designated sites in Anchar lake (Srinagar, J&K, India) to assess its heavy metal (Cu, Cr, Zn, Ni, Cd, Pb) load and changes on seasonal basis. The concentration of heavy metals was determined using atomic absorption spectroscopy. Most of the samples were found within limits of maximum permissible concentrations as recommended by WHO (Guidelines for drinking water quality, pp 491-493, 2006). During all the seasons, highest concentration of all heavy metals (Cu, Cr, Zn, Ni, Cd, Pb) was recorded at highly polluted sites of the lake viz. near agricultural fields (S1), near settlements (S3) and SKIMS (S4). These sites received huge agrochemical run-off from the surrounding agricultural fields, solid and liquid wastes from the nearby catchment areas and effluents from Sher-e-Kashmir Institute of Medical Sciences (SKIMS) compared to control site lake centre (S5). Furthermore, most of the metals in water and sediment were found with highest concentration during autumn (Viz., Cu-1.5 ppm; Zn-0.38 ppm; Ni-1.89 ppm; Pb-0.84 ppm in water and Cu-26.9 ppm; Zn-13.6 ppm; Pb-4.33 ppm in sediment) and summer (Viz., Cr-0.68 ppm in water and Ni-4.8 ppm; Cd-2.6 ppm; Cr-8.01 ppm in sediment) seasons. Also in Lemna minor plant highest concentration was observed during summer season (Cu-29.09 ppm; Zn-19.11 ppm; Ni-5.7 ppm; Cd-1.34 ppm; Cr-9.18 ppm and Pb-9.77 ppm). From these observations, it was found that the sources of heavy metals in Anchar lake were both natural and anthropogenic ones. This study recommended that continuous monitoring of heavy metals (Viz; Cu, Cr, Zn, Ni, Cd and Pb) in water, sediment and other aquatic biota of Anchar lake should be directed to protection of ecological status of the lake and its surrounding area.

Comparative investigation of toxicity and bioaccumulation of Cd-based quantum dots and Cd salt in freshwater plant Lemna minor L.

Science.gov (United States)

Modlitbová, Pavlína; Novotný, Karel; Pořízka, Pavel; Klus, Jakub; Lubal, Přemysl; Zlámalová-Gargošová, Helena; Kaiser, Jozef

2018-01-01

The purpose of this study was to determine the toxicity of two different sources of cadmium, i.e. CdCl 2 and Cd-based Quantum Dots (QDs), for freshwater model plant Lemna minor L. Cadmium telluride QDs were capped with two coating ligands: glutathione (GSH) or 3-mercaptopropionic acid (MPA). Growth rate inhibition and final biomass inhibition of L. minor after 168-h exposure were monitored as toxicity endpoints. Dose-response curves for Cd toxicity and EC50 168h values were statistically evaluated for all sources of Cd to uncover possible differences among the toxicities of tested compounds. Total Cd content and its bioaccumulation factors (BAFs) in L. minor after the exposure period were also determined to distinguish Cd bioaccumulation patterns with respect to different test compounds. Laser-Induced Breakdown Spectroscopy (LIBS) with lateral resolution of 200µm was employed in order to obtain two-dimensional maps of Cd spatial distribution in L. minor fronds. Our results show that GSH- and MPA-capped Cd-based QDs have similar toxicity for L. minor, but are significantly less toxic than CdCl 2 . However, both sources of Cd lead to similar patterns of Cd bioaccumulation and distribution in L. minor fronds. Our results are in line with previous reports that the main mediators of Cd toxicity and bioaccumulation in aquatic plants are Cd 2+ ions dissolved from Cd-based QDs. Copyright © 2017 Elsevier Inc. All rights reserved.

Mercury induced oxidative stress, DNA damage, and activation of antioxidative system and Hsp70 induction in duckweed (Lemna minor).

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Zhang, Tingting; Lu, Qianqian; Su, Chunlei; Yang, Yaru; Hu, Dan; Xu, Qinsong

2017-09-01

Mercury uptake and its effects on physiology, biochemistry and genomic stability were investigated in Lemna minor after 2 and 6d of exposure to 0-30μM Hg. The accumulation of Hg increased in a concentration- and duration-dependent manner, and was positively correlated with the leaf damage. Oxidative stress after Hg exposure was evidenced in L. minor by a significant decrease in photosynthetic pigments, an increase in malondialdehyde and lipoxygenase activities (total enzyme activity and isoenzymes activity). Fronds of L. minor exposed to Hg showed an induction of peroxidase, catalase, and ascorbate peroxidase activities (total enzyme activity and some isoenzymes activities). Exposure of L. minor to Hg reduced the activity (total enzyme activity and some isoenzymes activities) of glutathione reductase, and superoxide dismutase. Exposure to Hg produced a transient increase in the content of glutathione and ascorbic acid. The content of dehydroascorbate and oxidized glutathione in L. minor were high during the entire exposure period. Exposure of L. minor to Hg also caused the accumulation of proline and soluble sugars. The amplification of new bands and the absence of normal DNA amplicons in treated plants in the random amplified polymorphic DNA (RAPD) profile indicated that genomic template stability (GTS) was affected by Hg treatment. The accumulation of Hsp70 indicated the occurrence of a heat shock response at all Hg concentrations. These results suggest that L. minor plants were able to cope with Hg toxicity through the activation of various mechanisms involving enzymatic and non-enzymatic antioxidants, up-regulation of proline, and induction of Hsp70. Copyright © 2017 Elsevier Inc. All rights reserved.

Field based investigation on phytoremediation potentials of Lemna minor and Azolla filiculoides in tropical, semiarid regions: Case of Ethiopia.

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Amare, Elfu; Kebede, Fassil; Berihu, Tesfay; Mulat, Worku

2017-10-16

This study investigated the concurrent accumulation of eight heavy metals by two floating aquatic macrophytes (Lemna minor and Azolla filiculoides) cultivated in ambient media and blended wastewaters in the semiarid regions of Ethiopia. Both species accumulated heavy metals in varying degrees with a significant concentration gradient within the immediate water media. Highest bioconcentration factor was determined for Mn and Fe in both plants. Results revealed that L. minor was high phytoaccumulator for Fe, Mn, Zn and Co but moderate for Cd, Cu, Ni and Cr. On the other hand, A. filiculoides was a high accumulator for Fe, Mn, Zn and Cu, but its potency was moderate for Co, Cr and Ni, but lower for Cd. Both species exhibited significant difference in accumulating Co, Zn and Mn (p < 0.05). In general, the bioconcentration factors for both plants were comparable within the same treatment. In this study, stronger associations between the heavy metal concentrations in the plant tissues and in the grown water media were observed for A. filiculoides.

Duckweed Lemna minor as a tool for testing toxicity of coal residues and polluted sediments

Energy Technology Data Exchange (ETDEWEB)

Jenner, H.A.; Janssen-Mommen, J.P.M. (Kema Environmental Services, Arnhem (Netherlands))

1993-07-01

Duckweed, Lemna minor, was used for testing single elements and leachates of coal ashes and sediments by expressing growth as surface coverage. The EC50 for the elements Cd, Cu, Zn, As(III), As(V), Se(IV), Se(VI), SeO[sub 2] were 0.86, 2.2, 4.4, 8.4, 297, 21, 67, 37 [mu]M respectively. Leachates were tested of pulverized coal fuel ash (PFA), including 'low NO[sub x]' ashes, coal gasification slag (CGS), and, as a reference, the polluted sediments of a canal. The concentrations of elements in leachates of 'low NO[sub x]' PFA were higher than those in leachates of conventional PFA. The leaching of anions from PFA was quicker than the cations. CGS showed an absolutely minimal element leaching. Comparison of the effects of conventional PFA with sediments from Rotterdam harbor, River Rhine, and the canal shows PFA to be the far less toxic one. The sediment samples from the canal demonstrated strong growth inhibition, probably due to high zinc concentrations originating from industrial activity.

Duckweed Lemna minor as a tool for testing toxicity of coal residues and polluted sediments

Energy Technology Data Exchange (ETDEWEB)

Jenner, H A; Janssen-Mommen, J P.M. [Kema Environmental Services, Arnhem (Netherlands)

1993-07-01

Duckweed, Lemna minor, was used for testing single elements and leachates of coal ashes and sediments by expressing growth as surface coverage. The EC50 for the elements Cd, Cu, Zn, As(III), As(V), Se(IV), Se(VI), SeO[sub 2] were 0.86, 2.2, 4.4, 8.4, 297, 21, 67, 37 [mu]M respectively. Leachates were tested of pulverized coal fuel ash (PFA), including 'low NO[sub x]' ashes, coal gasification slag (CGS), and, as a reference, the polluted sediments of a canal. The concentrations of elements in leachates of 'low NO[sub x]' PFA were higher than those in leachates of conventional PFA. The leaching of anions from PFA was quicker than the cations. CGS showed an absolutely minimal element leaching. Comparison of the effects of conventional PFA with sediments from Rotterdam harbor, River Rhine, and the canal shows PFA to be the far less toxic one. The sediment samples from the canal demonstrated strong growth inhibition, probably due to high zinc concentrations originating from industrial activity.

A full evaluation for the enantiomeric impacts of lactofen and its metabolites on aquatic macrophyte Lemna minor.

Science.gov (United States)

Wang, Fang; Liu, Donghui; Qu, Han; Chen, Li; Zhou, Zhiqiang; Wang, Peng

2016-09-15

Pesticide pollution of surface water represents a considerable danger for the aquatic plants which play very crucial roles in aquatic system such as oxygen production, nutrient cycling, water quality controlling and sediment stabilization. In this work, the toxic effects of the chiral herbicide lactofen and its three metabolites (desethyl lactofen, acifluorfene and amino acifluorfene) to the aquatic plant Lemna minor (L. minor) on enantiomeric level were evaluated. The influences on growth rate, fresh weight, content of photosynthetic pigment, protein and malondialdehyde (MDA) and the activities of antioxidant defense enzymes (catalase (CAT) and superoxide dismutase (SOD)) were measured after 7 days of exposure. L. minor growth was inhibited in the order of (S)-desethyl lactofen > racemic-desethyl lactofen > (R)-desethyl lactofen > racemic-lactofen > (S)-lactofen > (R)-lactofen > acifluorfene > amino acifluorfene, and the IC50 (7d) values showed desethyl lactofen was the most powerful compound which was about twice as toxic as lactofen. The contents of chlorophylls (Chl) and carotenoids (Car) were significantly reduced by the chemicals, while, the levels of protein, MDA and the activity of CAT and SOD enzymes increased in most cases. The obtained results revealed that lactofen and its metabolites had an undesirable effect on L. minor, in terms of physiological and biochemical aspects. Besides, enantioselective toxicity of lactofen and desethyl lactofen to L. minor was observed. The S-enantiomer of desethyl lactofen was more toxic than the corresponding R-enantiomer. Furthermore, racemic lactofen was more toxic than the individual enantiomers. The side effects of pesticide metabolites and the enantioselectivity should be considered in developing optically pure products and risk assessment. Copyright © 2016 Elsevier Ltd. All rights reserved.

纳米ZnO对浮萍(Lemna minor L.)的生态毒性及其聚集性和溶解性分析%Ecotoxicity of ZnO Nanoparticles on Duckweed(Lemna minor L.) and Analysis on Its Aggregation and Dissolution

Institute of Scientific and Technical Information of China (English)

胡长伟; 刘旭

2012-01-01

The extensive production and application of nanoparticles increase the risk of their environmental release. In this study, duckweed {Lemna minor L.) was exposed to ZnO nanoparticles at different doses(0, 1, 10 mg·L‐1 and 50 mg·L‐1) for 7 d. The influences of the nanoparticles on D665/D665a(ratio of chlorophyll and phoeophytin) and activities of SOD, CAT, POD and Na+K+-ATPase were investigated. In addition, aggregation and dissolution of ZnO nanoparticles were tested. The results showed that the activities of SOD, CAT and POD were significantly increased at 50 mg·L‐1 nanoparticle concentration and decreased when treated with ZnSO4 (Zn2+ 10 mg·L‐1), indicative of an antioxidant stress from the nanoparticles. Whereas, D665/D665a and the activity of Na+K+-ATPase were significantly suppressed. ZnO nanoparticles were inclined to aggregate and precipitate in the culture media, and all nanoparticles settled within 12 h. The concentrations of Zn2+ dissolved from the nanoparticles in the 1 mg·L‐1, 10 mg·L‐1 and 50 mg·L‐1 groups were 0.62 mg·L‐1, 1.86 mg·L‐1 and 2.76 mg·L‐1, respectively, and they were not in proportion to the nanoparticles added to the culture media. The results indicated that 50 mg · L‐1 nanoparticles could bring an evident stress to duckweed(Lemna minor L.). The source of toxicity may mainly be the Zn2+ released by the ZnO nanoparticles.%纳米颗粒的大量生产和应用增加了其环境释放风险,为此以不同浓度的纳米ZnO(O、1、10 mg·L-1和50 mg·L-1)处理浮萍(Lemna minor L.)7 d,分析了纳米颗粒对植物D665/D665a值(叶绿素与脱镁叶绿素的比率)以及超氧化物歧化酶(SOD)、过氧化氢酶(CAT)、过氧化物酶(POD)和Na+K+-ATP酶(Na+K+-ATPase)活性的影响,并对纳米ZnO的聚集性与溶解性进行了测试.研究结果显示,浓度为50 mg· L-1的纳米颗粒显著抑制D665/D665a�

Differential oxidative and antioxidative response of duckweed Lemna minor toward plant growth promoting/inhibiting bacteria.

Science.gov (United States)

Ishizawa, Hidehiro; Kuroda, Masashi; Morikawa, Masaaki; Ike, Michihiko

2017-09-01

Bacteria colonizing the plant rhizosphere are believed to positively or negatively affect the host plant productivity. This feature has inspired researchers to engineer such interactions to enhance crop production. However, it remains to be elucidated whether rhizobacteria influences plant oxidative stress vis-a-vis other environmental stressors, and whether such influence is associated with their growth promoting/inhibiting ability. In this study, two plant growth-promoting bacteria (PGPB) and two plant growth-inhibiting bacteria (PGIB) were separately inoculated into axenic duckweed (Lemna minor) culture under laboratory conditions for 4 and 8 days in order to investigate their effects on plant oxidative stress and antioxidant activities. As previously characterized, the inoculation of PGPB and PGIB strains accelerated and reduced the growth of L. minor, respectively. After 4 and 8 days of cultivation, compared to the PGPB strains, the PGIB strains induced larger amounts of O 2 •- , H 2 O 2 , and malondialdehyde (MDA) in duckweed, although all bacterial strains consistently increased O 2 •- content by two times more than that in the aseptic control plants. Activities of five antioxidant enzymes were also elevated by the inoculation of PGIB, confirming the severe oxidative stress condition in plants. These results suggest that the surface attached bacteria affect differently on host oxidative stress and its response, which degree correlates negatively to their effects on plant growth. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

Influence of sublethal concentrations of sulfur dioxide on morphology, growth, and product yield of the duckweed Lemna minor L

Energy Technology Data Exchange (ETDEWEB)

Fankhauser, H; Brunold, C; Erismann, K H

1976-01-01

There was no disturbance in the growth of Lemna minor L. with a SO/sub 2/ concentration of up to 0.3 ppM in air. A SO/sub 2/ concentration of 0.6 ppM caused an initial depression of the growth rate of about 25 percent, but in the course of adaptation, the rate rose to the values of the control. The average dry weight per frond was not influenced by the SO/sub 2/ fumigation. The initial sporadic appearance of chloroses by fumigation with 0.6 ppM SO/sub 2/ was considered a sign of the proximate toxicity limit for Lemna minor L. With 0.15 ppM SO/sub 2/ in air, the size of the fronds was reduced. The average surface of the fronds was diminished by 0.3 ppM SO/sub 2/ for about 16 percent as compared with the control plants. The protein remained quantitatively unafffected up to a SO/sub 2/ concentration of 0.6 ppM. As a qualitative influence of SO/sub 2/, the nitrogen content of the proteins remained constant, but the sulfur content of the proteins increased. Under 0.3 and 0.6 ppM SO/sub 2/, the starch content decreased immediately by 20 to 30 percent, under 0.15 ppM SO/sub 2/ the decrease reached the same level after a longer time than in the case of the higher concentrations. The SO/sub 2/ concentrations up to 0.6 ppM had no effect on chlorophyll concentration. The contents of C, N, H, P, K, Na, Ca, Mg, Mn, and Fe were not affected by SO/sub 2/ fumigation. It is concluded that SO/sub 2/ may have some effect on product yield, even under low concentrations, without provoking acute damage; the plant is able to adapt by regulation of its metabolism, and enters a new steady state.

Lemna minor plants chronically exposed to ionising radiation: RNA-seq analysis indicates a dose rate dependent shift from acclimation to survival strategies.

Science.gov (United States)

Van Hoeck, Arne; Horemans, Nele; Nauts, Robin; Van Hees, May; Vandenhove, Hildegarde; Blust, Ronny

2017-04-01

Ecotoxicological research provides knowledge on ionising radiation-induced responses in different plant species. However, the sparse data currently available are mainly extracted from acute exposure treatments. To provide a better understanding of environmental exposure scenarios, the response to stress in plants must be followed in more natural relevant chronic conditions. We previously showed morphological and biochemical responses in Lemna minor plants continuously exposed for 7days in a dose-rate dependent manner. In this study responses on molecular (gene expression) and physiological (photosynthetic) level are evaluated in L. minor plants exposed to ionising radiation. To enable this, we examined the gene expression profiles of irradiated L. minor plants by using an RNA-seq approach. The gene expression data reveal indications that L. minor plants exposed at lower dose rates, can tolerate the exposure by triggering acclimation responses. In contrast, at the highest dose rate tested, a high number of genes related to antioxidative defense systems, DNA repair and cell cycle were differentially expressed suggesting that only high dose rates of ionising radiation drive L. minor plants into survival strategies. Notably, the photosynthetic process seems to be unaffected in L. minor plants among the tested dose rates. This study, supported by our earlier work, clearly indicates that plants shift from acclimation responses towards survival responses at increasing dose rates of ionising radiation. Copyright © 2017 Elsevier B.V. All rights reserved.

β-Radiation Stress Responses on Growth and Antioxidative Defense System in Plants: A Study with Strontium-90 in Lemna minor

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Arne Van Hoeck

2015-07-01

Full Text Available In the following study, dose dependent effects on growth and oxidative stress induced by β-radiation were examined to gain better insights in the mode of action of β-radiation induced stress in plant species. Radiostrontium (90Sr was used to test for β-radiation induced responses in the freshwater macrophyte Lemna minor. The accumulation pattern of 90Sr was examined for L. minor root and fronds separately over a seven-day time period and was subsequently used in a dynamic dosimetric model to calculate β-radiation dose rates. Exposing L. minor plants for seven days to a 90Sr activity concentration of 25 up to 25,000 kBq·L−1 resulted in a dose rate between 0.084 ± 0.004 and 97 ± 8 mGy·h−1. After seven days of exposure, root fresh weight showed a dose dependent decrease starting from a dose rate of 9.4 ± 0.5 mGy·h−1. Based on these data, an EDR10 value of 1.5 ± 0.4 mGy·h−1 was estimated for root fresh weight and 52 ± 17 mGy·h−1 for frond fresh weight. Different antioxidative enzymes and metabolites were further examined to analyze if β-radiation induces oxidative stress in L. minor.

β-Radiation Stress Responses on Growth and Antioxidative Defense System in Plants: A Study with Strontium-90 in Lemna minor.

Science.gov (United States)

Van Hoeck, Arne; Horemans, Nele; Van Hees, May; Nauts, Robin; Knapen, Dries; Vandenhove, Hildegarde; Blust, Ronny

2015-07-07

In the following study, dose dependent effects on growth and oxidative stress induced by β-radiation were examined to gain better insights in the mode of action of β-radiation induced stress in plant species. Radiostrontium (⁹⁰Sr) was used to test for β-radiation induced responses in the freshwater macrophyte Lemna minor. The accumulation pattern of 90Sr was examined for L. minor root and fronds separately over a seven-day time period and was subsequently used in a dynamic dosimetric model to calculate β-radiation dose rates. Exposing L. minor plants for seven days to a ⁹⁰Sr activity concentration of 25 up to 25,000 kBq·L⁻¹ resulted in a dose rate between 0.084 ± 0.004 and 97 ± 8 mGy·h⁻¹. After seven days of exposure, root fresh weight showed a dose dependent decrease starting from a dose rate of 9.4 ± 0.5 mGy·h⁻¹. Based on these data, an EDR10 value of 1.5 ± 0.4 mGy·h⁻¹ was estimated for root fresh weight and 52 ± 17 mGy·h⁻¹ for frond fresh weight. Different antioxidative enzymes and metabolites were further examined to analyze if β-radiation induces oxidative stress in L. minor.

Modeling the interaction of light intensity, nutrient concentration and uranium toxicity in Lemna minor

Energy Technology Data Exchange (ETDEWEB)

Zimmer, E.; Horemans, N.; Vandenhove, H. [Belgian Nuclear Research Centre SCK-CEN (Belgium); Cedergreen, N. [University of Copenhagen (Denmark); Jager, T. [Vrije Universiteit Amsterdam (Netherlands)

2014-07-01

Radioecology aims at assessing the effect of radionuclides and radiation on the environment. Since we cannot test every possible environmental situation in the laboratory, we need modeling approaches to extrapolate the results of toxicity assays to environmentally relevant scenarios. Therefore, it is of crucial importance to understand the effect of relevant environmental factors, such as nutrients, temperature and light on the toxicity of the test. Radionuclides are often found to induce the production of reactive oxygen species (ROS). In plants, an overload of ROS can lead to disturbances of the photosynthetic system. Since the light intensity determines the efficiency of the photo-systems in plants, it can be expected to interact with the effect of radionuclides. The nutrient concentration of the test medium determines the physiological state of the plant, affecting in turn the plant's capability of dealing with stress and hence influences the toxicity of the contaminant. To study the interaction of stressors with environmental conditions, mechanistic effect modeling is promoted widely in ecotoxicology. In principle, the modelling aims at a mechanistic understanding of the different processes causing the stress individually, and integrating them in one framework to study their joint effect and possible interaction. We here present a mechanistic effect model for Lemna minor (common duckweed), which is based on Dynamic Energy Budget (DEB) theory. Models based on DEB have been used widely to study the effects of compounds on animals. Due to its general applicability to all types of organisms, it holds potential to be used for comparison of species and compounds in a broad context. Energy uptake from the environment is modeled explicitly, and metabolic rates are set to depend on temperature in DEB models. Therefore, they can be used to extrapolate effects to a wide range of environmentally relevant scenarios. Until now, the DEB research in ecotoxicology has

The Minimization of Organic and Metallic Industrial Waste Via LEMNA MINOR Concentration

Science.gov (United States)

1992-12-30

from municipal and industrial waste waters. Duckweed is a floating, widespread and fast-growing plant. It is smal, 3asy to cultivate and highly sensitive...and Cairns, J. Jr., "Accumulation and Depuration of Metals by Duckweed (Lemna perpusilla)," Ecotoxicology and Environmental Safety, 5, 87-96, 1981...to separate substances of different densities. calla: a plant of the arum family, native to South Africa, but cultivated in the United States, and

The Response of Duckweed (Lemna minor L. Roots to Cd and Its Chemical Forms

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Yan Xue

2018-01-01

Full Text Available The response of duckweed (Lemna minor L. roots to Cd and its chemical forms was investigated. The relative root growth rate and concentrations of Cd and its different chemical forms in the root, that is, ethanol-extractable (FE-Cd, HCl-extractable (FHCl-Cd, and residual fractions (Fr-Cd, were quantified. Weibull model was used to unravel the regression between the relative root elongation (RRL with chemical forms of Cd. Parameters assessed catalase (CAT, peroxidases (POD, and superoxide dismutase (SOD, as well as malondialdehyde (MDA and total antioxidant capacity (A-TOC. Our results show that both the relative root growth rate and relative frond number were affected by Cd concentrations. The chemical forms of Cd were influenced by Cd content in the medium. Relative root elongation (RRL showed a significant correlation with chemical forms of Cd. Additionally, POD and SOD increased at lower Cd concentrations followed by a decrease at higher Cd concentrations (at more than 5 μM Cd. Moreover, MDA and A-TOC increased and CAT decreased with increasing Cd exposure. Furthermore, CAT showed a significant correlation with FHCl-Cd. Taken together, it can be concluded that the chemical forms of Cd are statistically significant predictors of Cd toxicity to duckweed and to the other similar aquatic plants.

Combined effects of elevated CO_2 and Cd-contaminated water on growth, photosynthetic response, Cd accumulation and thiolic components status in Lemna minor L

International Nuclear Information System (INIS)

Pietrini, F.; Bianconi, D.; Massacci, A.; Iannelli, M.A.

2016-01-01

Highlights: • Elevated CO_2 did not affect the ability of L. minor plants to accumulate Cd in their tissues. • Elevated CO_2 decreased Cd toxicity in L. minor plants by increasing photosynthesis. • Elevated CO_2 reduced Cd toxicity in duckweed by enhancing antioxidant system. - Abstract: The objective of this study was to investigate the combined effects of elevated CO_2 and cadmium (Cd) treatments on growth, photosynthetic efficiency and phytoremediation ability in Lemna minor L. Plants of L. minor were exposed to different Cd concentrations (0, 1.5, 2.5 and 5 mg L"−"1 Cd) for periods of 24, 48 and 72 h at ambient (AC) and at elevated (EC) CO_2 (350 and 700 ppm, respectively). Cadmium concentration, bioconcentration factor, enzyme activities and thiols content enhanced in plants with the increase of Cd treatments, time of exposure and at both CO_2 levels. Glutathione levels increased only at AC. Growth, photosynthetic and chlorophyll fluorescence parameters, and the reduced glutathione to oxidized glutathione ratio declined in plants with increasing exposure time, Cd treatments and at both CO_2 levels. Our results suggested that the alleviation of toxicity, at low Cd doses, observed in L. minor grown at EC is dependent on both increased photosynthesis and an enhanced antioxidant capacity.

Combined effects of elevated CO2 and Cd-contaminated water on growth, photosynthetic response, Cd accumulation and thiolic components status in Lemna minor L.

Science.gov (United States)

Pietrini, F; Bianconi, D; Massacci, A; Iannelli, M A

2016-05-15

The objective of this study was to investigate the combined effects of elevated CO2 and cadmium (Cd) treatments on growth, photosynthetic efficiency and phytoremediation ability in Lemna minor L. Plants of L. minor were exposed to different Cd concentrations (0, 1.5, 2.5 and 5 mg L(-1) Cd) for periods of 24, 48 and 72 h at ambient (AC) and at elevated (EC) CO2 (350 and 700 ppm, respectively). Cadmium concentration, bioconcentration factor, enzyme activities and thiols content enhanced in plants with the increase of Cd treatments, time of exposure and at both CO2 levels. Glutathione levels increased only at AC. Growth, photosynthetic and chlorophyll fluorescence parameters, and the reduced glutathione to oxidized glutathione ratio declined in plants with increasing exposure time, Cd treatments and at both CO2 levels. Our results suggested that the alleviation of toxicity, at low Cd doses, observed in L. minor grown at EC is dependent on both increased photosynthesis and an enhanced antioxidant capacity. Copyright © 2016 Elsevier B.V. All rights reserved.

Light-dark regulation of sulfate assimilation in Lemna minor L. in the presence of o-acetyl-l-serine

International Nuclear Information System (INIS)

Brunold, C.; Neuenschwander, U.

1989-01-01

The effect of light removal and addition of O-acetyl-l-serine (OAS) on sulfate assimilation in Lemna minor L. was analyzed by measuring the extractable activity of adenosine 5'-phosphosulfate sulfotransferase (APSSTase) and the in vivo incorporation of 35 SO 4 2- . After removal of light APSSTase activity decreased to 10% within 24 h in the absence and to 50% in the presence of OAS. Within 24 h total 35 SO 4 2- uptake decreased to 60% without and increased to 130% with OAS compared to light controls. The incorporation of 35 S into cysteine increased 2 times without and 15 times with OAS, labelling of glutathione decreased to 65% and increased to 140%, the one of the protein fraction decreased to 30% and to 20% of the light control in the absence and presence of OAS. Our results indicate that OAS has a regulatory function on the assimilation of sulfate and that protein synthesis is inhibited in the dark

Fabrication and characterization of mesoporous activated carbon from Lemna minor using one-step H{sub 3}PO{sub 4} activation for Pb(II) removal

Energy Technology Data Exchange (ETDEWEB)

Huang, Yang, E-mail: zzsfxyhy@163.com; Li, Shunxing; Lin, Haibin; Chen, Jianhua

2014-10-30

Graphical abstract: - Highlights: • Activated carbon was prepared from Lemna minor using H{sub 3}PO{sub 4} activation. • Materials have higher mesoporosity (92.2%) and more oxygen and nitrogen-containing functional groups. • Materials can remove Pb(II) rapidly with monolayer adsorption capacity (170.9 mg/g). • The adsorption process fitted to Langmuir isotherm and pseudo-first-order kinetic. • Materials could be used as an economical, efficient adsorbent to remove Pb(II) ions. - Abstract: A low cost and locally available material, Lemna minor, was used to fabricate activated carbon using H{sub 3}PO{sub 4} activation. After H{sub 3}PO{sub 4} activation, the L. minor activated carbons (LACs) possess high mesoporosity (92.2%) and a surface area of 531.9 m{sup 2}/g according to Brunauer–Emmett–Teller (BET) analysis. Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectrometer (XPS) analyses reveal the presence of rich hydroxyl, carboxyl, amide and phosphate functional groups on the LACs surface, leading to facile Pb(II) binding to the surface through strong chemisorptive bonds or ion-exchange. The kinetic and equilibrium data were well described by pseudo-first-order model and Langmuir isotherm, with the maximum monolayer adsorption capacity (q{sub m}) 170.9 mg/g at 25 °C. The intra-particle diffusion mechanism was partially responsible for the adsorption. The adsorption process was spontaneous and endothermic with negative ΔG and positive ΔH. The Pb(II)-loaded LACs could be easily regenerated using 0.1-M HCl and reused for seven cycles without significant adsorption capacity reduction. The maximum percentage removal rate for Pb(II) (20 mg/L) was found to be 91.8% within 30 min, at optimum conditions of pH 6.0 and 25 °C. These suggested that the low-cost LACs could be used as a potential adsorbent in the treatment of lead-contaminated water.

Ecotoxicological evaluation of propranolol hydrochloride and losartan potassium to Lemna minor L. (1753) individually and in binary mixtures.

Science.gov (United States)

Godoy, Aline A; Kummrow, Fábio; Pamplin, Paulo Augusto Z

2015-07-01

Antihypertensive pharmaceuticals, including the beta-blockers, are one of the most detected therapeutic classes in the environment. The ecotoxicity of propranolol hydrochloride and losartan potassium was evaluated, both individually and combined in a binary mixture, by using the Lemna minor growth inhibition test. The endpoints evaluated in the single-pharmaceutical tests were frond number, total frond area and fresh weight. For the evaluation of the mixture toxicity, the selected endpoint was frond number. Water quality criteria values (WQC) were derived for the protection of freshwater and saltwater pelagic communities regarding the effects induced by propranolol and losartan using ecotoxicological data from the literature, including our data. The risks associated with both pharmaceutical effects on non-target organisms were quantified through the measured environmental concentration (MEC)/predicted-no-effect concentration (PNEC) ratios. For propranolol, the total frond area was the most sensitive endpoint (EC50 = 77.3 mg L(-1)), while for losartan there was no statistically significant difference between the endpoints. Losartan is only slightly more toxic than propranolol. Both concentration addition and independent action models overestimated the mixture toxicity of the pharmaceuticals at all the effect concentration levels evaluated. The joint action of both pharmaceuticals showed an antagonistic interaction to L. minor. Derived WQC assumed lower values for propranolol than for losartan. The MEC/PNEC ratios showed that propranolol may pose a risk for the most sensitive aquatic species, while acceptable risks posed by losartan were estimated for most of aquatic matrices. To the authors knowledge these are the first data about losartan toxicity for L. minor.

Content of biogenic amines in Lemna minor (common duckweed) growing in medium contaminated with tetracycline.

Science.gov (United States)

Baciak, Michał; Sikorski, Łukasz; Piotrowicz-Cieślak, Agnieszka I; Adomas, Barbara

2016-11-01

Aquatic plants are continuously exposed to a variety of stress factors. No data on the impact of antibiotics on the biogenic amines in duckweed (Lemna minor) have been available so far, and such data could be significant, considering the ecological role of this plant in animal food chains. In the tissues of control (non-stressed) nine-day-old duckweed, the following biogenic amines were identified: tyramine, putrescine, cadaverine, spermidine and spermine. Based on the tetracycline contents and the computed EC values, the predicted toxicity units have been calculated. The obtained results demonstrated phytoxicity caused by tetracycline in relation to duckweed growth rate, yield and the contents of chlorophylls a and b. The carotenoid content was not modified by tetracycline. It was found that tetracycline as a water pollutant was a stress factor triggering an increase in the synthesis of amines. Tetracycline at 19, 39 and 78μM concentrations increased biogenic amine synthesis by 3.5 times. Although the content of tyramine increased fourteen times with the highest concentration of the drug (and of spermidine - only three-fold) the increase of spermidine was numerically the highest. Among the biogenic amines the most responsive to tetracycline were spermine and tyramine, while the least affected were putrescine and spermidine. Despite putrescine and spermidine being the least sensitive, their sum of contents increased five-fold compared to the control. These studies suggest that tetracycline in water reservoirs is taken up by L. minor as the antibiotic clearly modifies the metabolism of this plant and it may likely pose a risk. Copyright © 2016 Elsevier B.V. All rights reserved.

Sodium chloride as a reference substance for the three growth endpoints used in the Lemna minor L. (1753 test

Directory of Open Access Journals (Sweden)

Aline Andrade Godoy

2017-01-01

Full Text Available Lemna sp. growth inhibition test standardized protocols suggest the use of compounds such as 3,5-dichlorophenol as reference substances for checking the test organism’s sensitivity routinely. However, this and other recommended chemicals present risks to human health and to the environment. Sodium chloride (NaCl appears as a less toxic alternative reference substance which has been successfully used in routine ecotoxicological tests. However, the evaluation of this compound in multiple growth endpoints used in the L. minor test, which is required for recommending it as a reference substance for this test organism, has not yet been reported. In the present study, NaCl was tested with L. minor for the growth endpoints frond number, total frond area and fresh weight. Results showed acceptable sensitivity and reproducibility (coefficient of variance < 15.0% for all three of the measured endpoints. Statistically significant differences were observed between the EC50 values calculated based on the three endpoints (p < 0.05. Total frond area was the most sensitive one, with average EC50 value of 2742.80 ± 245.7 mg L-1. It was anticipated that NaCl can be a suitable alternative reference substance and that total frond area should be the endpoint of choice for sensitivity toxicity tests using NaCl.

A multigenerational effect of parental age on offspring size but not fitness in common duckweed (Lemna minor).

Science.gov (United States)

Barks, P M; Laird, R A

2016-04-01

Classic theories on the evolution of senescence make the simplifying assumption that all offspring are of equal quality, so that demographic senescence only manifests through declining rates of survival or fecundity. However, there is now evidence that, in addition to declining rates of survival and fecundity, many organisms are subject to age-related declines in the quality of offspring produced (i.e. parental age effects). Recent modelling approaches allow for the incorporation of parental age effects into classic demographic analyses, assuming that such effects are limited to a single generation. Does this 'single-generation' assumption hold? To find out, we conducted a laboratory study with the aquatic plant Lemna minor, a species for which parental age effects have been demonstrated previously. We compared the size and fitness of 423 laboratory-cultured plants (asexually derived ramets) representing various birth orders, and ancestral 'birth-order genealogies'. We found that offspring size and fitness both declined with increasing 'immediate' birth order (i.e. birth order with respect to the immediate parent), but only offspring size was affected by ancestral birth order. Thus, the assumption that parental age effects on offspring fitness are limited to a single generation does in fact hold for L. minor. This result will guide theorists aiming to refine and generalize modelling approaches that incorporate parental age effects into evolutionary theory on senescence. © 2016 European Society For Evolutionary Biology. Journal of Evolutionary Biology © 2016 European Society For Evolutionary Biology.

Influence of nutrient medium composition on uranium toxicity and choice of the most sensitive growth related endpoint in Lemna minor.

Science.gov (United States)

Horemans, Nele; Van Hees, May; Saenen, Eline; Van Hoeck, Arne; Smolders, Valérie; Blust, Ronny; Vandenhove, Hildegarde

2016-01-01

Uranium (U) toxicity is known to be highly dependent on U speciation and bioavailability. To assess the impact of uranium on plants, a growth inhibition test was set up in the freshwater macrophyte Lemna minor. First growth media with different compositions were tested in order to find a medium fit for testing U toxicity in L. minor. Following arguments were used for medium selection: the ability to sustain L. minor growth, a high solubility of U in the medium and a high percentage of the more toxic U-species namely UO2(2+). Based on these selection criteria a with a low phosphate concentration of 0.5 mg L(-1) and supplemented with 5 mM MES (2-(N-morpholino)ethanesulfonic acid) to ensure pH stability was chosen. This medium also showed highest U toxicity compared to the other tested media. Subsequently a full dose response curve for U was established by exposing L. minor plants to U concentrations ranging from 0.05 μM up to 150 μM for 7 days. Uranium was shown to adversely affect growth of L. minor in a dose dependent manner with EC10, EC30 and EC50 values ranging between 1.6 and 4.8 μM, 7.7-16.4 μM and 19.4-37.2 μM U, respectively, depending on the growth endpoint. Four different growth related endpoints were tested: frond area, frond number, fresh weight and dry weight. Although differences in relative growth rates and associated ECx-values calculated on different endpoints are small (maximal twofold difference), frond area is recommended to be used to measure U-induced growth effects as it is a sensitive growth endpoint and easy to measure in vivo allowing for measurements over time. Copyright © 2015 Elsevier Ltd. All rights reserved.

Combined effects of elevated CO{sub 2} and Cd-contaminated water on growth, photosynthetic response, Cd accumulation and thiolic components status in Lemna minor L

Energy Technology Data Exchange (ETDEWEB)

Pietrini, F.; Bianconi, D.; Massacci, A. [Institute of Agro-Environmental and Forest Biology, National Research Council of Italy, Via Salaria Km 29,300, 00015 Monterotondo Scalo, Roma (Italy); Iannelli, M.A., E-mail: adelaide.iannelli@ibba.cnr.it [Institute of Agricultural Biology and Biotechnology, National Research Council of Italy, Via Salaria Km 29,300, 00015 Monterotondo Scalo, Roma (Italy)

2016-05-15

Highlights: • Elevated CO{sub 2} did not affect the ability of L. minor plants to accumulate Cd in their tissues. • Elevated CO{sub 2} decreased Cd toxicity in L. minor plants by increasing photosynthesis. • Elevated CO{sub 2} reduced Cd toxicity in duckweed by enhancing antioxidant system. - Abstract: The objective of this study was to investigate the combined effects of elevated CO{sub 2} and cadmium (Cd) treatments on growth, photosynthetic efficiency and phytoremediation ability in Lemna minor L. Plants of L. minor were exposed to different Cd concentrations (0, 1.5, 2.5 and 5 mg L{sup −1} Cd) for periods of 24, 48 and 72 h at ambient (AC) and at elevated (EC) CO{sub 2} (350 and 700 ppm, respectively). Cadmium concentration, bioconcentration factor, enzyme activities and thiols content enhanced in plants with the increase of Cd treatments, time of exposure and at both CO{sub 2} levels. Glutathione levels increased only at AC. Growth, photosynthetic and chlorophyll fluorescence parameters, and the reduced glutathione to oxidized glutathione ratio declined in plants with increasing exposure time, Cd treatments and at both CO{sub 2} levels. Our results suggested that the alleviation of toxicity, at low Cd doses, observed in L. minor grown at EC is dependent on both increased photosynthesis and an enhanced antioxidant capacity.

Fitorremediación mediante el uso de dos especies vegetales Lemna minor (Lenteja de agua), y Eichornia crassipes (Jacinto de agua) en aguas residuales producto de la actividad minera

OpenAIRE

Jaramillo Jumbo, Mariuxi Del Cisne; Flores Campoverde, Edison Darío

2012-01-01

La contaminación del agua con metales pesados es un problema de gran importancia, aunque existen varios métodos convencionales para su remoción estos son muy costosos por lo que la fitorremediación es una alternativa que utiliza plantas para reducir la concentración de dichos contaminantes. En este trabajo se determinó la capacidad de absorción del mercurio mediante el uso de las macrófitas acuáticas Eichornia crassipes y Lemna minor en diferentes condiciones experimentales. A las macrófit...

Citric acid enhanced the antioxidant defense system and chromium uptake by Lemna minor L. grown in hydroponics under Cr stress.

Science.gov (United States)

Sallah-Ud-Din, Rasham; Farid, Mujahid; Saeed, Rashid; Ali, Shafaqat; Rizwan, Muhammad; Tauqeer, Hafiz Muhammad; Bukhari, Syed Asad Hussain

2017-07-01

Phytoextraction is a cost-effective and eco-friendly technique for the removal of pollutants, mainly heavy metal(loids) especially from polluted water and metal-contaminated soils. The phytoextraction of heavy metals is, in general, limited due to the low availability of heavy metals in the growth medium. Organic chelators can help to improve the phytoextraction by increasing metal mobility and solubility in the growth medium. The present research was carried out to examine the possibility of citric acid (CA) in improving chromium (Cr) phytoextraction by Lemna minor (duckweed). For this purpose, healthy plants were collected from nearby marsh and grown in hydroponics under controlled conditions. Initial metal contents of both marsh water and plant were measured along with physico-chemical properties of the marsh water. Different concentrations of Cr and CA were applied in the hydroponics in different combinations after defined intervals. Continuous aeration was supplied and pH maintained at 6.5 ± 0.1. Results showed that increasing concentration of Cr significantly decreased the plant biomass, photosynthetic pigments, leaf area, and antioxidant enzyme activities (like catalase, ascorbate peroxidase, superoxide dismutase, peroxidase). Furthermore, Cr stress increased the Cr concentrations, electrolyte leakage, hydrogen peroxide, and malondialdehyde contents in plants. The addition of CA alleviated the Cr-induced toxicity in plants and further enhanced the Cr uptake and its accumulation in L. minor. The addition of CA enhanced the Cr concentration in L. minor by 6.10, 26.5, 20.5, and 20.2% at 0, 10, 100, and 200 μM Cr treatments, respectively, compared to the respective Cr treatments without CA. Overall, the results of the present study showed that CA addition may enhance the Cr accumulation and tolerance in L. minor by enhancing the plant growth and activities of antioxidant enzymes.

Effect of zinc and lead on the physiological and biochemical properties of aquatic plant Lemna minor: its potential role in phytoremediation

Science.gov (United States)

Jayasri, M. A.; Suthindhiran, K.

2017-06-01

Plants have gained importance in situ bioremediation of heavy metals. In the present study, different concentrations of zinc (Zn2+) (0.5, 5, 10, 15, 20 mg/l) and lead (Pb2+) (1, 2, 4, 6, 8 mg/l) were used to evaluate metal tolerance level of Lemna minor. L.minor were exposed to metals for 4 days and tested for its dry to fresh weight ratio (DW/FW), photosynthetic pigments production and protein content. The oxidative damage was detected by measuring catalase activity. L.minor showed tolerance against Zn2+ and Pb2+ at a concentration of 10 and 4 mg/l, respectively. Among the metals, Pb2+ showed a significant toxicity at 8 mg/l. High concentration (20 mg/l of Zn2+ and 8 mg/l of Pb2+) of the metals displayed a considerable negative effect on soluble proteins (13 fold decrease with Zn2+ and 4 fold decrease with Pb2+) and photosynthetic pigments (twofold decrease with Zn2+ and onefold decrease with Pb2+) and lead to a consequent reduction in number of fronds. Further, the catalase was greatly increased (twofold decrease with Zn2+ and sixfold decrease with Pb2+) under metal stress. The results indicate that L.minor withstands Zn2+ and Pb2+ toxicity up to the concentration of 10 and 4 mg/l, respectively. Hence, the metal tolerant property of this plant shall be exploited for bioremediation of Zinc and Lead in polluted water. Further, the detailed and wide range of heavy metal toxicity studies should be done to reveal the possible use of this plant on large scale bioremediation purpose.

Interaction of Sulfate Assimilation with Carbon and Nitrogen Metabolism in Lemna minor1

Science.gov (United States)

Kopriva, Stanislav; Suter, Marianne; von Ballmoos, Peter; Hesse, Holger; Krähenbühl, Urs; Rennenberg, Heinz; Brunold, Christian

2002-01-01

Cysteine synthesis from sulfide and O-acetyl-l-serine (OAS) is a reaction interconnecting sulfate, nitrogen, and carbon assimilation. Using Lemna minor, we analyzed the effects of omission of CO2 from the atmosphere and simultaneous application of alternative carbon sources on adenosine 5′-phosphosulfate reductase (APR) and nitrate reductase (NR), the key enzymes of sulfate and nitrate assimilation, respectively. Incubation in air without CO2 led to severe decrease in APR and NR activities and mRNA levels, but ribulose-1,5-bisphosphate carboxylase/oxygenase was not considerably affected. Simultaneous addition of sucrose (Suc) prevented the reduction in enzyme activities, but not in mRNA levels. OAS, a known regulator of sulfate assimilation, could also attenuate the effect of missing CO2 on APR, but did not affect NR. When the plants were subjected to normal air after a 24-h pretreatment in air without CO2, APR and NR activities and mRNA levels recovered within the next 24 h. The addition of Suc and glucose in air without CO2 also recovered both enzyme activities, with OAS again influenced only APR. 35SO42− feeding showed that treatment in air without CO2 severely inhibited sulfate uptake and the flux through sulfate assimilation. After a resupply of normal air or the addition of Suc, incorporation of 35S into proteins and glutathione greatly increased. OAS treatment resulted in high labeling of cysteine; the incorporation of 35S in proteins and glutathione was much less increased compared with treatment with normal air or Suc. These results corroborate the tight interconnection of sulfate, nitrate, and carbon assimilation. PMID:12428005

The Applicability of Lemna aequinoctialis to Growth Inhibition Test of Lemna minor%青萍生长抑制试验对稀脉浮萍的适用性研究

Institute of Scientific and Technical Information of China (English)

梁艺怀; 张琨; 张京佶; 刘敏; 赵华清; 殷浩文

2015-01-01

为了验证我国本土常见的稀脉浮萍(Lemna aequinoctialis)是否适用于以青萍(Lemna minor)作为标准试验生物的生长抑制试验,对两种浮萍的毒性效应终点和毒性响应差异进行比较.通过对两种浮萍的总叶面积、干重、鲜重同叶状体数之间的相关性进行分析,根据《OECD化学品测试准则No.221浮萍生长抑制试验》,遵从良好实验室规范(GLP),将两种浮萍暴露于参比物质3,5-二氯苯酚,进行7d更新式毒性试验,暴露浓度为(1.0 ～ 10) mg·L-1.结果表明,青萍的培养条件、试验方法以及毒性效应终点均适用于稀脉浮萍,两种浮萍的毒性试验呈现出相似的时间-效应关系和剂量-效应关系,两者的毒性效应浓度具有可比性,且数值上接近.以上实验结果可以得出,稀脉浮萍适用于生长抑制试验;鉴于稀脉浮萍在我国分布广泛、容易获取,稀脉浮萍可作为毒性测试的国家标准试验生物.

Functional Response (FR) and Relative Growth Rate (RGR) Do Not Show the Known Invasiveness of Lemna minuta (Kunth)

Science.gov (United States)

Boets, Pieter; Goethals, Peter L. M.

2016-01-01

Growing travel and trade threatens biodiversity as it increases the rate of biological invasions globally, either by accidental or intentional introduction. Therefore, avoiding these impacts by forecasting invasions and impeding further spread is of utmost importance. In this study, three forecasting approaches were tested and combined to predict the invasive behaviour of the alien macrophyte Lemna minuta in comparison with the native Lemna minor: the functional response (FR) and relative growth rate (RGR), supplemented with a combined biomass-based nutrient removal (BBNR). Based on the idea that widespread invasive species are more successful competitors than local, native species, a higher FR and RGR were expected for the invasive compared to the native species. Five different nutrient concentrations were tested, ranging from low (4 mgN.L-1 and 1 mgP.L-1) to high (70 mgN.L-1 and 21 mgP.L-1). After four days, a significant amount of nutrients was removed by both Lemna spp., though significant differences among L. minor and L. minuta were only observed at lower nutrient concentrations (lower than 17 mgN.L-1 and 6 mgP.L-1) with higher nutrient removal exerted by L. minor. The derived FR did not show a clear dominance of the invasive L. minuta, contradicting field observations. Similarly, the RGR ranged from 0.4 to 0.6 d-1, but did not show a biomass-based dominance of L. minuta (0.5 ± 0.1 d-1 versus 0.63 ± 0.09 d-1 for L. minor). BBNR showed similar results as the FR. Contrary to our expectations, all three approaches resulted in higher values for L. minor. Consequently, based on our results FR is sensitive to differences, though contradicted the expectations, while RGR and BBNR do not provide sufficient power to differentiate between a native and an invasive alien macrophyte and should be supplemented with additional ecosystem-based experiments to determine the invasion impact. PMID:27861603

Possible role of jasmonic acid in the regulation of floral induction, evocation and floral differentiation in Lemna minor L.

Science.gov (United States)

Krajncic, B; Kristl, J; Janzekovic, I

2006-01-01

Jasmonic acid (JA) is implicated in a wide variety of developmental and physiological processes in plants. Here, we studied the effects of JA and the combination of JA and ethylenediamine-dio-hydroxyphenyl-acetic acid (EDDHA) on flowering in Lemna minor in axenical cultures. JA (0.475-47.5 nmol l(-1)) enhanced floral induction in L. minor under long-day (LD) conditions. Under the same conditions, at a concentration of 237.5 nmol l(-1), JA inhibited floral induction, and at a concentration of 475 nmol l(-1) it prevented floral induction. Under LD conditions with LD preculture, a combination of EDDHA (20,500 nmol l(-1)) and JA (47.5 nmol l(-1)) had a synergistic effect on the promotion of floral induction. Floral induction was enhanced to the greatest extent in experiments with LD precultures. Microscopic examination of microphotographs of histological sections showed that JA and, to an even greater extent, JA+EDDHA at optimal concentrations promote apical floral induction (evocation). Furthermore, JA, and to an even greater extent JA in combination with EDDHA in an optimal concentration, also promote flower differentiation, especially the development of stamens, as is evident from the microphotographs. The experimental results show that JA promotes floral induction in other species of Lemnaceae from various groups according to their photoperiodic response. The results support our hypothesis that, in addition to previously ascribed functions, JA may regulate floral induction, evocation and floral differentiation. Our hypothesis is supported also by the results obtained by quantitative determination of endogenous JA levels in L. minor at three growth stages. The levels of endogenous JA decreased from 389 ng JA g(-1) (fresh weight) of L. minor during the vegetative stage to 217 ng JA g(-1) during the evocation stage, and to 37.5 ng JA g(-1) during the flowering stage, which proves that JA is used for flowering.

Low-temperature X-ray microanalysis of the differentiating vascular tissue in root tips of Lemna minor L

Energy Technology Data Exchange (ETDEWEB)

Echlin, P [Univ. of Cambridge, England; Lai, C E; Hayes, T L

1982-06-01

The fracture faces of bulk-frozen tissue offer a number of advantages for the analysis of diffusible elements. They are easy to prepare, remain uncontaminated, and, unlike most frozen-hydrated sections, can be shown to exist in a fully hydrated state throughout examination and analysis. Root tips of Lemna minor briefly treated with a polymeric cryoprotectant are quench frozen in melting nitrogen. Fractures are prepared using the AMRAY Biochamber, lightly etched if necessary to reveal surface detail and carbon coated while maintaining the specimen at 110 K. The frozen-hydrated fracture faces are analyzed at 110 K using the P/B ratio method which is less sensitive to changes in surface geometry and variations in beam current. The method has been used to investigate the distribution of seven elements (Na/sup +/, Mg/sup + +/, P, S, Cl/sup -/, K/sup +/ and Ca/sup + +/) in the developing vascular tissue of the root tip. The microprobe can measure relative elemental ratios at the cellular level and the results from this present study reveal important variations in different parts of the root. The younger, more actively dividing cells, appear to have a slightly higher concentration of diffusible ions in comparison to the somewhat older tissues which have begun to differentiate into what are presumed to be functional vascular elements.

Ecotoxiocological Studies of Niger Delta Sediments using Duckweed (L. Minor) Growth Inhibition Test

International Nuclear Information System (INIS)

Olajire, A. A.; Alternburger, R.; Brack, W.

2003-01-01

This study was undertaken to evaluate the toxicity of sediments collected from the Niger Delta (Nigeria) to Lemna minor, a sensitive aquatic weed regularly used for ecotoxicological studies. Also, the study wanted to determine if L. minor can be used as an effective bioassay organism by oil companies and chemical industries in Nigeria. Essentially, the experimental approach involved exposure of L. minor under standard laboratory conditions to sediments and toxicity is presented as percent inhibition of growth of L. minor cultures after 7 days. The result of the present study showed that there is differential toxicity among the sediments analyzed, and we found that for 0.25mg/ml of growth rate (%1) decreases in the order: SDOGN(42.6%) >SDWRR (33.7%)> SDALD (20.5%) >SDUGBO (17.1%) ? SDWRR were clorotic and had lost their roots, indicating the very high toxicity of the soluble organic contaminants in these sediments. Lemna minor proved to be a practical bioassay organism because the L. minor toxicity test is simple, sensitive and cost effective

The use of Lemna Minor (duckweed) to control the water quality in relation to coal residues. Gebruik van eendekroos voor het bewaken van de waterkwaliteit in relatie met kolenreststoffen

Energy Technology Data Exchange (ETDEWEB)

Janssen-Mommen, J P.M.; Jenner, H A [KEMA Milieu Services, Arnhem (Netherlands)

1993-01-01

Lemna Minor can be applied as a phytomonitor in a standardized test for ecotoxicological investigations of leachate extracts of coal residues and (water)soils. A standardized test method has been developed for fortnight toxicity experiments. The toxicity and the uptake of individual elements were studied in accumulation experiments.Special attention is paid to the impact of the factors complexation, interaction and speciation on the biological availability of the elements. Coal residues and water soils are leached and the leachate extracts are tested for growth restraint by means of the test method. It appears that the use of duckweed as a phytomonitor is a technically simple and reliable method

Characterizing dose response relationships: Chronic gamma radiation in Lemna minor induces oxidative stress and altered polyploidy level

International Nuclear Information System (INIS)

Van Hoeck, Arne; Horemans, Nele; Van Hees, May; Nauts, Robin; Knapen, Dries; Vandenhove, Hildegarde; Blust, Ronny

2015-01-01

The biological effects and interactions of different radiation types in plants are still far from understood. Among different radiation types, external gamma radiation treatments have been mostly studied to assess the biological impact of radiation toxicity in organisms. Upon exposure of plants to gamma radiation, ionisation events can cause, either directly or indirectly, severe biological damage to DNA and other biomolecules. However, the biological responses and oxidative stress related mechanisms under chronic radiation conditions are poorly understood in plant systems. In the following study, it was questioned if the Lemna minor growth inhibition test is a suitable approach to also assess the radiotoxicity of this freshwater plant. Therefore, L. minor plants were continuously exposed for seven days to 12 different dose rate levels covering almost six orders of magnitude starting from 80 μGy h"−"1 up to 1.5 Gy h"−"1. Subsequently, growth, antioxidative defence system and genomic responses of L. minor plants were evaluated. Although L. minor plants could survive the exposure treatment at environmental relevant exposure conditions, higher dose rate levels induced dose dependent growth inhibitions starting from approximately 27 mGy h"−"1. A ten-percentage growth inhibition of frond area Effective Dose Rate (EDR_1_0) was estimated at 95 ± 7 mGy h"−"1, followed by 153 ± 13 mGy h"−"1 and 169 ± 12 mGy h"−"1 on fresh weight and frond number, respectively. Up to a dose rate of approximately 5 mGy h"−"1, antioxidative enzymes and metabolites remained unaffected in plants. A significant change in catalase enzyme activity was found at 27 mGy h"−"1 which was accompanied with significant increases of other antioxidative enzyme activities and shifts in ascorbate and glutathione content at higher dose rate levels, indicating an increase in oxidative stress in plants. Recent plant research hypothesized that environmental genotoxic

Characterizing dose response relationships: Chronic gamma radiation in Lemna minor induces oxidative stress and altered polyploidy level.

Science.gov (United States)

Van Hoeck, Arne; Horemans, Nele; Van Hees, May; Nauts, Robin; Knapen, Dries; Vandenhove, Hildegarde; Blust, Ronny

2015-12-01

The biological effects and interactions of different radiation types in plants are still far from understood. Among different radiation types, external gamma radiation treatments have been mostly studied to assess the biological impact of radiation toxicity in organisms. Upon exposure of plants to gamma radiation, ionisation events can cause, either directly or indirectly, severe biological damage to DNA and other biomolecules. However, the biological responses and oxidative stress related mechanisms under chronic radiation conditions are poorly understood in plant systems. In the following study, it was questioned if the Lemna minor growth inhibition test is a suitable approach to also assess the radiotoxicity of this freshwater plant. Therefore, L. minor plants were continuously exposed for seven days to 12 different dose rate levels covering almost six orders of magnitude starting from 80 μGy h(-1) up to 1.5 Gy h(-1). Subsequently, growth, antioxidative defence system and genomic responses of L. minor plants were evaluated. Although L. minor plants could survive the exposure treatment at environmental relevant exposure conditions, higher dose rate levels induced dose dependent growth inhibitions starting from approximately 27 mGy h(-1). A ten-percentage growth inhibition of frond area Effective Dose Rate (EDR10) was estimated at 95 ± 7 mGy h(-1), followed by 153 ± 13 mGy h(-1) and 169 ± 12 mGy h(-1) on fresh weight and frond number, respectively. Up to a dose rate of approximately 5 mGy h(-1), antioxidative enzymes and metabolites remained unaffected in plants. A significant change in catalase enzyme activity was found at 27 mGy h(-1) which was accompanied with significant increases of other antioxidative enzyme activities and shifts in ascorbate and glutathione content at higher dose rate levels, indicating an increase in oxidative stress in plants. Recent plant research hypothesized that environmental genotoxic stress conditions

Getting More Ecologically Relevant Information from Laboratory Tests: Recovery of Lemna minor After Exposure to Herbicides and Their Mixtures.

Science.gov (United States)

Knežević, Varja; Tunić, Tanja; Gajić, Pero; Marjan, Patricija; Savić, Danko; Tenji, Dina; Teodorović, Ivana

2016-11-01

Recovery after exposure to herbicides-atrazine, isoproturon, and trifluralin-their binary and ternary mixtures, was studied under laboratory conditions using a slightly adapted standard protocol for Lemna minor. The objectives of the present study were (1) to compare empirical to predicted toxicity of selected herbicide mixtures; (2) to assess L. minor recovery potential after exposure to selected individual herbicides and their mixtures; and (3) to suggest an appropriate recovery potential assessment approach and endpoint in a modified laboratory growth inhibition test. The deviation of empirical from predicted toxicity was highest in binary mixtures of dissimilarly acting herbicides. The concentration addition model slightly underestimated mixture effects, indicating potential synergistic interactions between photosynthetic inhibitors (atrazine and isoproturon) and a cell mitosis inhibitor (trifluralin). Recovery after exposure to the binary mixture of atrazine and isoproturon was fast and concentration-independent: no significant differences between relative growth rates (RGRs) in any of the mixtures (IC10 Mix , 25 Mix , and 50 Mix ) versus control level were recorded in the last interval of the recovery phase. The recovery of the plants exposed to binary and ternary mixtures of dissimilarly acting herbicides was strictly concentration-dependent. Only plants exposed to IC10 Mix , regardless of the herbicides, recovered RGRs close to control level in the last interval of the recovery phase. The inhibition of the RGRs in the last interval of the recovery phase compared with the control level is a proposed endpoint that could inform on reversibility of the effects and indicate possible mixture effects on plant population recovery potential.

Accumulation of 99Tc in duckweed Lemna minor L. as a function of growth rate and 99Tc concentration

International Nuclear Information System (INIS)

Hattink, J.; Wolterbeek, H.Th.

2001-01-01

This study focuses on the question of whether short-term studies can be used to forecast the accumulation of the long-lived fission product 99 Tc in duckweed, Lemna minor L., grown in the field; in other words, are the accumulation parameters independent of changing growth rates typical of natural populations of duckweed. Two processes determine the 99 Tc accumulation: (i) uptake and release of 99 TcO 4 - , characterised by a concentration factor, K d , and (ii) first-order reduction and complexation of Tc VII , characterised by k red . At various 99 Tc concentrations, the growth, total Tc and TcO 4 - accumulation were monitored over 10 days; parameters were fitted and compared with earlier results. Both K d and k red turn out to be independent of time, concentration and growth rate up to a concentration of 10 -6 mol l -1 99 TcO 4 - . Concentrations above this level result in toxic effects. The Tc accumulation in field populations of duckweed at Tc concentrations which generally occur in the environment can be forecasted by using the results from short-term experiments

Sorption of thorium (Ⅳ) from aqueous solutions by melamine modified lemna minor%三聚氰胺化学改性浮萍吸附重金属钍(Ⅳ)研究

Institute of Scientific and Technical Information of China (English)

杨司坤; 吴玮琳; 侯小娟; 吴方评; 陆建生; 向开祥

2017-01-01

采用生物吸附法去除废水中Th(Ⅳ)离子,研究了水生浮萍化学改性后吸附Th(Ⅳ)的行为特性、吸附模型及吸附机理.以浮萍、三聚氰胺和甲醛为原料,通过接枝反应制得三聚氰胺改性浮萍(MELM),能更好的吸附钍离子.结果表明:常温常压下,pH为5.5,吸附剂MELM为0.03 g,Th(Ⅳ)初始浓度为80 mg·L1,反应60 min时,最大吸附率为97.4％,对应吸附量为129.88 mg·g-1,吸附量比未经处理的浮萍(最优吸附条件下,吸附量为22.83 mg·g-1)吸附量要大.通过Langmuir、Freundlich、Temkin 3种等温吸附模型对数据进行拟合,Langmuir模型能更好的描述吸附剂MELM对Th(Ⅳ)的平衡吸附行为,同时吸附过程能很好的用准二级反应动力学来解释.此外,FTIR实验数据表明,吸附剂MELM表面上氨基、羟基和羰基是主要的作用基团.%Thorium(Ⅳ) ions sorption is investigated by melamine treated lemna minor from wastewater.Lemna minor reacted with melamine dissolve in formaldehyde (MELM) exhibited the highest thorium(Ⅳ) ions uptake capacity.The sorption process was optimized at pH 5.5,equilibrium time 60 min,initial Th(Ⅳ) mass concentration 80 mg·L-1 and adsorbent dose 0.03 g with 97.4％ of removal efficiency and 129.88 mg· g-1 of adsorption capacity,which is obviously greater than that (22.83 mg· g-1) of the untreated lemna minor for Th (Ⅳ) biosorption under the condition of optimization.The experimental data are analyzed by using isotherm and kinetic models.Kinetic data follow the pseudo-second-order model and equilibrium data agree very well with the Langmuir model.In addition,FTIR analysis indicates that hydroxyl,amino,and carbonyl groups act as the important roles in the adsorption process.

Toxicidade aguda e risco ambiental do antibiótico oxitetraciclina para tilápia ( Oreochromis niloticus , Daphnia magna e Lemna minor

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A.A. Machado

Full Text Available RESUMO O objetivo deste estudo foi classificar o antibiótico Terramicina(r de acordo com a toxicidade aguda e o risco de intoxicação ambiental para Oreochromis niloticus, Daphnia magna e Lemna minor, com base no seu ingrediente ativo oxitetraciclina (OTC. Além disso, observou-se a ocorrência de sinais de intoxicação aguda em peixes e o efeito da diluição do antibiótico sobre as variáveis de qualidade de água. Alevinos, neonatos e frondes foram expostos a concentrações de OTC. De acordo com os resultados dos testes de toxicidade aguda, a Terramicina(r foi classificada pela toxicidade aguda e pelo risco de intoxicação ambiental. Para O. niloticus, a CL(I50; 48h calculada foi de 6,92 mg L-1, para D. magna a CE(I50; 48h foi de 0,17mg.L-1, enquanto para L. minor a CI(I50;7d foi de 0,68 mg L-1. A Terramicina(r foi classificada como muito tóxica para O. niloticus e extremamente tóxica para D. magna e L. minor e causa risco de intoxicação ambiental para os três organismos testados. Concentrações de 7,5 e 8,0 mg L-1 de OTC reduziram a concentração de oxigênio dissolvido na água. De acordo com este estudo, a Terramicina(r não deve ser utilizada na aquicultura, pois é altamente tóxica e causa risco de intoxicação ambiental aos organismos teste.

Microbial Detoxification of Deoxynivalenol (DON), Assessed via a Lemna minor L. Bioassay, through Biotransformation to 3-epi-DON and 3-epi-DOM-1.

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Vanhoutte, Ilse; De Mets, Laura; De Boevre, Marthe; Uka, Valdet; Di Mavungu, José Diana; De Saeger, Sarah; De Gelder, Leen; Audenaert, Kris

2017-02-13

Mycotoxins are toxic metabolites produced by fungi. To mitigate mycotoxins in food or feed, biotransformation is an emerging technology in which microorganisms degrade toxins into non-toxic metabolites. To monitor deoxynivalenol (DON) biotransformation, analytical tools such as ELISA and liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) are typically used. However, these techniques do not give a decisive answer about the remaining toxicity of possible biotransformation products. Hence, a bioassay using Lemna minor L. was developed. A dose-response analysis revealed significant inhibition in the growth of L. minor exposed to DON concentrations of 0.25 mg/L and higher. Concentrations above 1 mg/L were lethal for the plant. This bioassay is far more sensitive than previously described systems. The bioassay was implemented to screen microbial enrichment cultures, originating from rumen fluid, soil, digestate and activated sludge, on their biotransformation and detoxification capability of DON. The enrichment cultures originating from soil and activated sludge were capable of detoxifying and degrading 5 and 50 mg/L DON. In addition, the metabolites 3-epi-DON and the epimer of de-epoxy-DON (3-epi-DOM-1) were found as biotransformation products of both consortia. Our work provides a new valuable tool to screen microbial cultures for their detoxification capacity.

Microbial Detoxification of Deoxynivalenol (DON, Assessed via a Lemna minor L. Bioassay, through Biotransformation to 3-epi-DON and 3-epi-DOM-1

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Ilse Vanhoutte

2017-02-01

Full Text Available Mycotoxins are toxic metabolites produced by fungi. To mitigate mycotoxins in food or feed, biotransformation is an emerging technology in which microorganisms degrade toxins into non-toxic metabolites. To monitor deoxynivalenol (DON biotransformation, analytical tools such as ELISA and liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS are typically used. However, these techniques do not give a decisive answer about the remaining toxicity of possible biotransformation products. Hence, a bioassay using Lemna minor L. was developed. A dose–response analysis revealed significant inhibition in the growth of L. minor exposed to DON concentrations of 0.25 mg/L and higher. Concentrations above 1 mg/L were lethal for the plant. This bioassay is far more sensitive than previously described systems. The bioassay was implemented to screen microbial enrichment cultures, originating from rumen fluid, soil, digestate and activated sludge, on their biotransformation and detoxification capability of DON. The enrichment cultures originating from soil and activated sludge were capable of detoxifying and degrading 5 and 50 mg/L DON. In addition, the metabolites 3-epi-DON and the epimer of de-epoxy-DON (3-epi-DOM-1 were found as biotransformation products of both consortia. Our work provides a new valuable tool to screen microbial cultures for their detoxification capacity.

Possible ecological risk of two pharmaceuticals diclofenac and paracetamol demonstrated on a model plant Lemna minor.

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Kummerová, Marie; Zezulka, Štěpán; Babula, Petr; Tříska, Jan

2016-01-25

Lemna minor is often used in environmental risk assessment and it can be supposed that usually evaluated parameters will be reliable even for assessing the risk of pharmaceuticals. Subtle changes in duckweed plant number, biomass production, and leaf area size induced by 10-day-exposure to diclofenac (DCF) and paracetamol (PCT) (0.1, 10, and 100 μg/L), excepting 100 μg/L DCF, are in contrast with considerable changes on biochemical and histochemical level. Both drugs caused a decrease in content of photosynthetic pigments (by up to 50%), an increase in non-photochemical quenching (by 65%) and decrease in relative chlorophyll fluorescence decay values (by up to 90% with DCF). Both DCF and especially PCT increased amount of reactive nitrogen and oxygen species in roots. DCF-induced effects included mainly increased lipid peroxidation (by 78%), disturbation in membrane integrity and lowering both oxidoreductase and dehydrogenase activities (by 30%). PCT increased the content of soluble proteins and phenolics. Higher concentrations of both DCF and PCT increased the levels of oxidised ascorbate (by 30%) and oxidised thiols (by up to 84% with DCF). Glutathion-reductase activity was elevated by both pharmaceuticals (nearly by 90%), glutathion-S-transferase activity increased mainly with PCT (by 22%). The early and sensitive indicators of DCF and PCT phytotoxicity stress in duckweed are mainly the changes in biochemical processes, connected with activation of defense mechanisms against oxidative stress. Copyright © 2015 Elsevier B.V. All rights reserved.

Stress responses of duckweed (Lemna minor L.) and water velvet (Azolla filiculoides Lam.) to anionic surfactant sodium-dodecyl-sulphate (SDS).

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Forni, C; Braglia, R; Harren, F J M; Cristescu, S M

2012-04-01

Surfactants are used for several purposes and recently they have attracted the attention for their ability to modify the behavior of other preexistent or co-disposed contaminants, although their use or discharge in wastewaters can represent a real or potential risk for the environment. Lemna minor L. and Azolla filiculoides Lam. are floating aquatic macrophytes, very effective in accumulating several pollutants including sodium dodecyl sulphate (SDS). In this work we evaluated the effects of SDS on these species by determining the stress ethylene production via laser-based trace gas detection, and the activities of enzymes involved in stress response, such as guaiacol peroxidase (G-POD), phenylalanine ammonia-lyase (PAL) and polyphenol-oxidase (PPO). Phenolics content was also determined. The macrophytes were treated with different concentrations of SDS for one week. SDS affected duckweed enzymatic activities and phenol content. While in the fern phenolics amount, PAL, G-POD and PPO activities were not affected by SDS except for 100 ppm SDS, the only concentration that was taken up and not completely degraded. Stress ethylene production was induced only in the fern treated with 50 and 100 ppm SDS. Copyright © 2011 Elsevier B.V. All rights reserved.

Biological stress responses induced by alpha radiation exposure in Lemna minor

Energy Technology Data Exchange (ETDEWEB)

Van Hoeck, A.; Horemans, N.; Van Hees, M.; Nauts, R. [Belgian Nuclear Research Centre SCK-CEN (Belgium); Knapen, D.; Blust, R. [University of Antwerp (Belgium)

2014-07-01

To enhance the robustness of radiation protection criteria for biota, additional information on the biological impact of radionuclides on non-human biota is needed. In particular the effects of alpha emitting isotopes have been poorly studied within a radioecological contextual though they exhibit a high linear energy transfer which can cause significant biological damage when taken up by organisms. Therefore, it is not only essential to measure alpha radiation toxicity, but also try to understand the underlying mechanisms of this stressor. The current study aimed to contribute to a better knowledge of the fundamental processes regulating alpha radiation stress response mechanisms in higher plants. {sup 241}Am was primarily selected as it is an almost pure alpha emitter and, as a daughter nuclide of {sup 241}Pu, it will become one of the dominant pollutants in plutonium affected areas. The aquatic macrophyte Lemna minor has proven its value in eco-toxicological research as representative of higher aquatic plants (OECD guideline nr. 221) and will be used to analyze alpha radiation stress in plant systems. An individual growth inhibition test was set up by means of single dose-response curve in order to identify the Effective Dose Rates (EDR-values) for frond size and biomass. As the mean path length is small for alpha particles, the accumulation of the radionuclide inside species represents almost exclusively the dosimetry. Therefore, quantification of {sup 241}Am uptake and {sup 241}Am distribution were evaluated separately for roots and fronds taking the activity concentrations of growth medium into account. Taken together with the respective dose conversion coefficients from the ERICA tool, this allowed to construct an accurate dosimetric model to determine internal and external dose rates. Different standard media were tested on growth rate and biomass to analyse the amount of {sup 241}Am taken up by the plants exposed from 2.5 to 100 kBq/L. From these

Lemna minor exposed to fluoranthene: growth, biochemical, physiological and histochemical changes.

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Zezulka, Stěpán; Kummerová, Marie; Babula, Petr; Váňová, Lucie

2013-09-15

Polycyclic aromatic hydrocarbons (PAHs) represent one of the major groups of organic contaminants in the aquatic environment. Duckweed (Lemna minor L.) is a common aquatic plant widely used in phytotoxicity tests for xenobiotic substances. The goal of this study was to assess the growth and the physiological, biochemical and histochemical changes in duckweed exposed for 4 and 10 days to fluoranthene (FLT, 0.1 and 1 mgL(-1)). Nonsignificant changes in number of plants, biomass production, leaf area size, content of chlorophylls a and b and carotenoids and parameters of chlorophyll fluorescence recorded after 4 and 10 days of exposure to FLT were in contrast with considerable changes at biochemical and histochemical levels. Higher occurrence of reactive oxygen species (ROS) caused by an exposure to FLT after 10 days as compared to control (hydrogen peroxide elevated by 13% in the 0.1 mgL(-1) and by 41% in the 1 mgL(-1) FLT; superoxide anion radical by 52% and 115% respectively) reflected in an increase in the activities of antioxidant enzymes (superoxide dismutase by 3% in both treatments, catalase by 9% and 1% respectively, ascorbate peroxidase by 21% and 5% respectively, guaiacol peroxidase by 12% in the 0.1 mgL(-1) FLT). Even the content of antioxidant compounds like ascorbate (by 20% in the 1 mgL(-1) FLT) or total thiols (reduced forms by 15% in the 0.1 mgL(-1) and 8% in the 1 mgL(-1) FLT, oxidized forms by 36% in the 0.1 mgL(-1) FLT) increased. Increased amount of ROS was followed by an increase in malondialdehyde content (by 33% in the 0.1 mgL(-1) and 79% in the 1 mgL(-1) FLT). Whereas in plants treated by the 0.1 mgL(-1) FLT the contents of total proteins and phenols increased by 15% and 25%, respectively, the 1 mgL(-1) FLT caused decrease of their contents by 32% and 7%. Microscopic observations of duckweed roots also confirmed the presence of ROS and related histochemical changes at the cellular and tissue levels. The assessment of phytotoxicity of organic

The Lemna minor growth inhibition test as basis to evaluate radiation or radionuclide-induced effects on freshwater plants

Energy Technology Data Exchange (ETDEWEB)

Horemans, N.; Van Hees, M.; Van Hoeck, A.; Vandenhove, H. [Belgian Nuclear Research Centre, SCK.CEN, Boeretang 200, 2400 Mol (Belgium)

2014-07-01

The setting of radiation protection criteria for wildlife is based on tiered Environmental Risk Assessments (ERA) methods. At various points in such a tiered ERA robust and transparent benchmark values are needed to indicate the levels of exposure that are considered safe to the environment. Although not ideal these benchmark values are today mainly based on laboratory-based experiments in which the toxic effects of radiation or radionuclides to one selected species exposed under standardised growth conditions is studied. As such an eco-toxicity test has been developed for the floating macrophyte Lemna minor that can be used to test the effect of different chemicals in freshwater. Here the use of this test to estimate effects of radiation or radionuclides and its relevance to the environment will be discussed. First single dose response curves are shown that were set up according to the guidelines for gamma, uranium and as a reference also cadmium. According to the guidelines growth inhibition can be calculated on different endpoints like frond number and frond area. The choice of this endpoint seems to be of major importance as dependent on the stressor significant shifts in the EC50 values, the concentration giving 50% effect, were observed. For gamma radiation a recovery experiment was set up in irradiated plants were allowed to grow again for 7 days in control conditions. It was shown that plant growth rate did not catch up with that of the non-irradiated group. On the contrary, plant cultures that showed a growth inhibition above 40% immediately after irradiation completely collapsed during the recovery period indicating no recovery from the gamma induced damage and resulting in a 3-fold lower EC50 value after 7 days recovery. The relevance of these data to the environment will be further discussed. Finally the influence of different cations on the uranium speciation and toxicity are studied. These experiments are the first steps to set up a biotic ligand

History and sensitivity comparison of the Spirodela polyrhiza microbiotest and Lemna toxicity tests

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Baudo R.

2015-01-01

Full Text Available The history of toxicity tests with duckweeds shows that these assays with free-floating aquatic angiosperms are gaining increasing attention in ecotoxicological research and applications. Standard tests have been published by national and international organizations, mainly with the test species Lemna minor and Lemna gibba. Besides the former two test species the great duckweed Spirodela polyrhiza is to date also regularly used in duckweed testing. Under unfavorable environmental conditions, the latter species produces dormant stages (turions and this has triggered the attention of two research groups from Belgium and Greece to jointly develop a “stock culture independent” microbiotest with S. polyrhiza. A 72 h new test has been worked out which besides its independence of stock culturing and maintenance of live stocks is very simple and practical to perform, and much less demanding in space and time than the conventional duckweed tests. Extensive International Interlaboratory Comparisons on the S. polyrhiza microbiotest showed its robustness and reliability and triggered the decision to propose this new assay to the ISO for endorsement and publication as a standard toxicity test for duckweeds. Sensitivity comparison of the 72 h S. polyrhiza microbiotest with the 7d L. minor assay for 22 compounds belonging to different groups of chemicals revealed that based on growth as the effect criterion both duckweed assays have a similar sensitivity. Taking into account its multiple advantages and assets, the S. polyrhiza microbiotest is a reliable and attractive alternative to the conventional duckweed tests.

Effects of exposure to nano and bulk sized TiO2 and CuO in Lemna minor.

Science.gov (United States)

Dolenc Koce, Jasna

2017-10-01

Nanoparticles of TiO 2 and CuO are among most commonly used nanoparticles, and elevated concentrations of them are expected to be found in all environments, including aquatic. A standard growth inhibition test ISO/CD 20079 was used to determine the toxicity of nano sized and larger micro sized (bulk) particles in the concentrations of 0.1, 1, 10, 100 and 1000 μM CuO and TiO 2 on common duckweed (Lemna minor L.). Both nano and bulk CuO particles caused changes in the structure and function of treated plants. The number of fronds and colonies decreased by as much as 78%, the length of roots and fronds decreased by 99% and 14%, respectively. Furthermore, photochemical efficiency was reduced by up to 35%, and the activities of antioxidative enzymes guaiacol peroxidase, ascorbate peroxidase and glutathione reductase increased by more than 240%. The altered physiological state of the CuO exposed plants was also reflected in the elevated occurrence of necrosis and bleaching in the duckweed colonies. Nano sized particles of CuO proved more phytotoxic than bulk particles, and the effects of both studied CuO sizes were concentration dependent. On the other hand, both bulk and nano sized particles of TiO 2 caused no severe phytotoxic effects, there was no concentration dependence and they could be considered as non-harmful to common duckweed. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

Fabrication and characterization of mesoporous activated carbon from Lemna minor using one-step H3PO4 activation for Pb(II) removal

Science.gov (United States)

Huang, Yang; Li, Shunxing; Lin, Haibin; Chen, Jianhua

2014-10-01

A low cost and locally available material, Lemna minor, was used to fabricate activated carbon using H3PO4 activation. After H3PO4 activation, the L. minor activated carbons (LACs) possess high mesoporosity (92.2%) and a surface area of 531.9 m2/g according to Brunauer-Emmett-Teller (BET) analysis. Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectrometer (XPS) analyses reveal the presence of rich hydroxyl, carboxyl, amide and phosphate functional groups on the LACs surface, leading to facile Pb(II) binding to the surface through strong chemisorptive bonds or ion-exchange. The kinetic and equilibrium data were well described by pseudo-first-order model and Langmuir isotherm, with the maximum monolayer adsorption capacity (qm) 170.9 mg/g at 25 °C. The intra-particle diffusion mechanism was partially responsible for the adsorption. The adsorption process was spontaneous and endothermic with negative ΔG and positive ΔH. The Pb(II)-loaded LACs could be easily regenerated using 0.1-M HCl and reused for seven cycles without significant adsorption capacity reduction. The maximum percentage removal rate for Pb(II) (20 mg/L) was found to be 91.8% within 30 min, at optimum conditions of pH 6.0 and 25 °C. These suggested that the low-cost LACs could be used as a potential adsorbent in the treatment of lead-contaminated water.

ACCUMULATION OF RECOMBINANT FUSION PROTEIN – SECRETORY ANALOG OF Ag85B AND ESAT6 MYCOBACTERIUM TUBERCULOSIS PROTEINS – IN TRANSGENIC Lemna minor L. PLANTS

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A.A.Peterson

2015-10-01

Full Text Available Determination of the presence of the recombinant fusion protein (ESAT6-Ag85B(ΔTMD-6His and its accumulation level in duckweed plants (Lemna minor L. was the aim of the research. ESAT6 and Ag85B are secretory proteins of Mycobacterium tuberculosis and are considered as potential candidates for development of new vaccine against tuberculosis (TB. Transgenic duckweed plants were obtained previously by Agrobacterium rhizogenes-mediated transformation and possessed fusion gene sequence esxA-fbpBΔTMD. Specific polyclonal antibodies were produced in immunized mice to identify levels of accumulation of TB antigens in plants. Recombinant antigen used for mice immunization was obtained in our laboratory by expression in E. coli. Western blot analysis revealed the recombinant tuberculosis antigen ESAT6-Ag85B(ΔTMD-6His in extracts from transgenic L. minor plants. The level of accumulation of the protein corresponds to 0.4-0.5 µg protein per 1 g of fresh weight of plant. Additionally, the accumulation of recombinant protein was investigated in lyophilized transgenic plants after 1.5 year storage. Duckweed plants accumulating a recombinant analogue of M. tuberculosis secretory proteins can be used for development of plant-based edible vaccines.

Carbon balance and productivity of Lemna gibba, a candidate plant for CELSS

Science.gov (United States)

Gale, J.; Smernoff, D. T.; Macler, B. A.; Macelroy, R. D.

1989-01-01

The photosynthesis and productivity of Lemna gibba is analyzed for CELSS based plant growth. Net photosynthesis of Lemna gibba is determined as a function of incident photosynthetic photon flux (PPF), with the light coming from above, below, or from both directions. Light from below is about 75 percent as effective as from above when the stand is sparse, but much less so with dense stands. High rates of photosynthesis are measured at 750 micromol / sq m per sec PPF and 1500 micromol/ mol CO2 at densities up to 660 g fresh weight (FW)/ sq m with young cultures. The analysis includes diagrams illustrating the net photosynthesis response to bilateral lighting of a sparse stand of low assimilate Lemna gibba; the effect of stand density on the net photosynthesis response to bilateral lighting of high assimilate Lemna gibba; the net photosynthesis response to ambient CO2 of sparse stands of Lemna gibba; and the time course of net photosynthesis and respiration per unit chamber and per unit dry weight of Lemna gibba.

Duckweed (Lemna minor) as a Model Plant System for the Study of Human Microbial Pathogenesis

Science.gov (United States)

Zhang, Yong; Hu, Yangbo; Yang, Baoyu; Ma, Fang; Lu, Pei; Li, Lamei; Wan, Chengsong; Rayner, Simon; Chen, Shiyun

2010-01-01

Background Plant infection models provide certain advantages over animal models in the study of pathogenesis. However, current plant models face some limitations, e.g., plant and pathogen cannot co-culture in a contained environment. Development of such a plant model is needed to better illustrate host-pathogen interactions. Methodology/Principal Findings We describe a novel model plant system for the study of human pathogenic bacterial infection on a large scale. This system was initiated by co-cultivation of axenic duckweed (Lemna minor) plants with pathogenic bacteria in 24-well polystyrene cell culture plate. Pathogenesis of bacteria to duckweed was demonstrated with Pseudomonas aeruginosa and Staphylococcus aureus as two model pathogens. P. aeruginosa PAO1 caused severe detriment to duckweed as judged from inhibition to frond multiplication and chlorophyll formation. Using a GFP-marked PAO1 strain, we demonstrated that bacteria colonized on both fronds and roots and formed biofilms. Virulence of PAO1 to duckweed was attenuated in its quorum sensing (QS) mutants and in recombinant strains overexpressing the QS quenching enzymes. RN4220, a virulent strain of S. aureus, caused severe toxicity to duckweed while an avirulent strain showed little effect. Using this system for antimicrobial chemical selection, green tea polyphenols exhibited inhibitory activity against S. aureus virulence. This system was further confirmed to be effective as a pathogenesis model using a number of pathogenic bacterial species. Conclusions/Significance Our results demonstrate that duckweed can be used as a fast, inexpensive and reproducible model plant system for the study of host-pathogen interactions, could serve as an alternative choice for the study of some virulence factors, and could also potentially be used in large-scale screening for the discovery of antimicrobial chemicals. PMID:21049039

Duckweed (Lemna minor as a model plant system for the study of human microbial pathogenesis.

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Yong Zhang

Full Text Available BACKGROUND: Plant infection models provide certain advantages over animal models in the study of pathogenesis. However, current plant models face some limitations, e.g., plant and pathogen cannot co-culture in a contained environment. Development of such a plant model is needed to better illustrate host-pathogen interactions. METHODOLOGY/PRINCIPAL FINDINGS: We describe a novel model plant system for the study of human pathogenic bacterial infection on a large scale. This system was initiated by co-cultivation of axenic duckweed (Lemna minor plants with pathogenic bacteria in 24-well polystyrene cell culture plate. Pathogenesis of bacteria to duckweed was demonstrated with Pseudomonas aeruginosa and Staphylococcus aureus as two model pathogens. P. aeruginosa PAO1 caused severe detriment to duckweed as judged from inhibition to frond multiplication and chlorophyll formation. Using a GFP-marked PAO1 strain, we demonstrated that bacteria colonized on both fronds and roots and formed biofilms. Virulence of PAO1 to duckweed was attenuated in its quorum sensing (QS mutants and in recombinant strains overexpressing the QS quenching enzymes. RN4220, a virulent strain of S. aureus, caused severe toxicity to duckweed while an avirulent strain showed little effect. Using this system for antimicrobial chemical selection, green tea polyphenols exhibited inhibitory activity against S. aureus virulence. This system was further confirmed to be effective as a pathogenesis model using a number of pathogenic bacterial species. CONCLUSIONS/SIGNIFICANCE: Our results demonstrate that duckweed can be used as a fast, inexpensive and reproducible model plant system for the study of host-pathogen interactions, could serve as an alternative choice for the study of some virulence factors, and could also potentially be used in large-scale screening for the discovery of antimicrobial chemicals.

Removal of chromium ions from wastewater by duckweed, Lemna minor L. by using a pilot system with continuous flow.

Science.gov (United States)

Uysal, Y

2013-12-15

The aim of this study was to determine the ability of Lemna minor to remove Cr (VI) ions from wastewater in a continuous flow pond system. This system was used to simulate a wastewater treatment pond and a natural wetland as habitat of plants. In order to find optimal conditions for chromium removal, ponds were operated with aqueous solutions having different pH (4.0-7.0) and chromium concentration of 0.25 mgCr(+6)/L, then plants were exposed to different chromium concentrations (0.25-5.0 mgCr(+6)/L) at pH 4.0. Chromium concentrations, both in biomass and wastewater, were measured and removal efficiency was determined throughout water flow. Growth factors such as growth rates, chlorophyll contents and dry/fresh weight ratios of plants were also determined to measure toxic effects of chromium. The percentages of chromium uptake (PMU) and bioconcentration factors (BCF) were calculated for each run. The highest accumulated chromium concentration (4.423 mgCr/g) was found in plants grown in the first chamber of pond operated at pH 4.0 and 5.0 mgCr/L, while the minimum accumulated chromium concentration (0.122 mgCr/g) was in plants grown in the last chamber of pond operated at pH 4.0 and 0.25 mgCr(+6)/L. Copyright © 2013 Elsevier B.V. All rights reserved.

Trophic transfer of Cd from duckweed (Lemna minor L.) to tilapia (Oreochromis mossambicus).

Science.gov (United States)

Xue, Yan; Peijnenburg, Willie J G M; Huang, Jin; Wang, Dengjun; Jin, Yan

2018-05-01

The transfer of the toxic heavy metal Cd from duckweed (Lemna minor L.) to the freshwater fish tilapia (Oreochromis mossambicus) was investigated. Concentrations of Cd in different chemical forms in duckweed and in different tissues (gut, edible muscle, and remnants or residual) of tilapia (i.e., ethanol-extractable fraction [F E ], HCl-extractable fraction [F HCl ], and residual fraction [F R ]) were quantified, and the bioaccumulation factors (BAFs) of Cd in the tilapia body were calculated. Simple linear regression analysis was used to unravel the correlation and accumulation mechanisms of Cd along the short food chain. Our results showed that with increasing exposure concentrations of Cd (0-50 μM for duckweed and 0-10 μM for tilapia), the total, F E (F e,d )-, F HCl (F h,d )-, and F R (F r,d )-Cd concentrations in duckweed and different tissues of tilapia increased progressively. The Cd sources (aqueous or dietary) influenced the BAF for Cd accumulation in the whole body of tilapia. Furthermore, regression analyses yielded significant positive correlations (R 2 > 0.96) between the Cd concentration in duckweed and in both the 3 parts and the whole body of tilapia. This finding suggests that Cd transfer from duckweed to tilapia can be quantitatively evaluated when tilapia is exposed only to duckweed. In addition, the linear regression between Cd accumulation in whole tilapia and F e,d -, F h,d -, and F r,d -Cd showed that particularly the correlation with F e,d -Cd is statistically significant (p < 0.001). The accumulated Cd concentrations and chemical forms in tilapia tissues also positively correlated with Cd sources (solution or duckweed). Compared with waterborne exposure only, duckweed especially increased the accumulation of Cd in the gut of tilapia. Taken together, our findings support a strong dependence of Cd accumulation and transfer from duckweed to tilapia on its chemical forms, especially on F e,d -Cd. This knowledge may expedite more

Accumulation of {sup 99}Tc in duckweed Lemna minor L. as a function of growth rate and {sup 99}Tc concentration

Energy Technology Data Exchange (ETDEWEB)

Hattink, J. E-mail: jhattink@hotmail.com; Wolterbeek, H.Th

2001-07-01

This study focuses on the question of whether short-term studies can be used to forecast the accumulation of the long-lived fission product {sup 99}Tc in duckweed, Lemna minor L., grown in the field; in other words, are the accumulation parameters independent of changing growth rates typical of natural populations of duckweed. Two processes determine the {sup 99}Tc accumulation: (i) uptake and release of {sup 99}TcO{sub 4}{sup -}, characterised by a concentration factor, K{sub d}, and (ii) first-order reduction and complexation of Tc{sup VII}, characterised by k{sub red}. At various {sup 99}Tc concentrations, the growth, total Tc and TcO{sub 4}{sup -} accumulation were monitored over 10 days; parameters were fitted and compared with earlier results. Both K{sub d} and k{sub red} turn out to be independent of time, concentration and growth rate up to a concentration of 10{sup -6} mol l{sup -1} {sup 99}TcO{sub 4}{sup -}. Concentrations above this level result in toxic effects. The Tc accumulation in field populations of duckweed at Tc concentrations which generally occur in the environment can be forecasted by using the results from short-term experiments.

Effects of treated industrial wastewaters and temperatures on growth and enzymatic activities of duckweed (Lemna minor L.).

Science.gov (United States)

Basiglini, E; Pintore, M; Forni, C

2018-05-30

The efficacy of the removal of contaminants from wastewater depends on physico-chemical properties of pollutants and the efficiency of treatment plant. Sometimes, low amounts of toxic compounds can be still present in the treated sewage. In this work we considered the effects of contaminant residues in treated wastewaters and of temperatures on Lemna minor L. Treated effluent waters were collected, analyzed and used as duckweed growth medium. In order to better understand the effects of micropollutants and seasonal variation, the plants were grown under ambient conditions for seven days in summer and winter. Relative growth rate, pigments and phenolic compounds concentrations were determined, as well as the activities of catalase (CAT), ascorbate peroxidase (APX), guaiacol peroxidase (G-POD) and polyphenol oxidase (PPO). The pollutant concentrations varied in the two seasons, depending on the industrial and municipal activities and efficiency of treatments. Treated waters contained heavy metals, nitrogenous and phosphorus compounds, surfactants and hydrocarbons. Compared to the control, duckweed growth of treated plants decreased by 25% in summer, while in the winter due to the lower temperatures and the presence of pollutants was completely impeded. The amounts of photosynthetic pigments of treated plants were not significantly affected in the summer, while they were higher than the control in the winter when the effluent had a high nitrogen amount. High CAT activity was registered in both seasons. Treated plants had significantly lower APX activity in the summer (53%) and winter (59%) respect to the controls. The observed inhibition of the peroxidase activities in the exposed plants, confirms the controversy existing in the literature about the variability of enzymatic response in stress condition. Copyright © 2018 Elsevier Inc. All rights reserved.

Root length of aquatic plant, Lemna minor L., as an optimal toxicity endpoint for biomonitoring of mining effluents.

Science.gov (United States)

Gopalapillai, Yamini; Vigneault, Bernard; Hale, Beverley A

2014-10-01

Lemna minor, a free-floating macrophyte, is used for biomonitoring of mine effluent quality under the Metal Mining Effluent Regulations (MMER) of the Environmental Effects Monitoring (EEM) program in Canada and is known to be sensitive to trace metals commonly discharged in mine effluents such as Ni. Environment Canada's standard toxicity testing protocol recommends frond count (FC) and dry weight (DW) as the 2 required toxicity endpoints-this is similar to other major protocols such as those by the US Environmental Protection Agency (USEPA) and the Organisation for Economic Co-operation and Development (OECD)-that both require frond growth or biomass endpoints. However, we suggest that similar to terrestrial plants, average root length (RL) of aquatic plants will be an optimal and relevant endpoint. As expected, results demonstrate that RL is the ideal endpoint based on the 3 criteria: accuracy (i.e., toxicological sensitivity to contaminant), precision (i.e., lowest variance), and ecological relevance (metal mining effluents). Roots are known to play a major role in nutrient uptake in conditions of low nutrient conditions-thus having ecological relevance to freshwater from mining regions. Root length was the most sensitive and precise endpoint in this study where water chemistry varied greatly (pH and varying concentrations of Ca, Mg, Na, K, dissolved organic carbon, and an anthropogenic organic contaminant, sodium isopropyl xanthates) to match mining effluent ranges. Although frond count was a close second, dry weight proved to be an unreliable endpoint. We conclude that toxicity testing for the floating macrophyte should require average RL measurement as a primary endpoint. © 2014 SETAC.

Assessment of Lemna minor (duckweed) and Corbicula fluminea (freshwater clam) as potential indicators of contaminated aquatic ecosystems: responses to presence of psychoactive drug mixtures.

Science.gov (United States)

Bourioug, Mohamed; Mazzitelli, Jean-Yves; Marty, Pierre; Budzinsky, Hélène; Aleya, Lotfi; Bonnafé, Elsa; Geret, Florence

2018-04-01

The pharmaceutical products are emerging pollutants continuously released into the environment, because they cannot be effectively removed by the wastewater treatment plants. In recent years, questions have been raised concerning the environmental risks related to these pollutants. The goal of this research was to evaluate the responses in Lemna minor after 7 days and in Corbicula fluminea after differing durations (1, 3, 7, and 19 days) of exposure to the psychoactive drug mixture (valproic acid, citalopram, carbamazepine, cyamemazine, hydroxyzine, oxazepam, norfluoxetine, lorazepam, fluoxetine, and sertraline) in different concentrations (0, 0 + ethanol, drug concentration (DC) 1 = river water concentration, DC2 = effluent concentration, and DC3 = 10× effluent concentration). In this aim, growth parameters of L. minor, gluthathione S-transferase (GSTs), catalase (CAT), ethoxyresorufin-O-deethylase (EROD) and/or gene expressions (pi-gst, cat, cytochrome P450 4 (cyp4), multidrug resistant 1 (mdr1), and superoxide dismutase (sod)) were measured. GST activities increased significantly in L. minor exposed to DC3, but no changes were found in CAT activity. In C. fluminea, EROD activity was induced significantly in both gill and digestive gland tissues after 3 days' exposure to DC3, while a GST increase was observed only in digestive gland tissues, suggesting that these pharmaceuticals induced an oxidative effect. Gene expression analysis revealed transient transcriptomic responses of cyp4, sod, and mdr1 under drug concentrations 2 or 3 and no change of expression for the other genes (cat and pi-gst) or condition (environmental drug concentration) tested. Finally, the data reported in this study represent important ecotoxicological information, confirming that this enzyme family (cyp4, sod, and mdr1) may be considered as a sensible and early indicator of exposure to drugs and emphasizing the involvement of selected genes in detoxification pathways.

EFFECTIVE CONCENTRATIONS OF 6 CONTAMINANTS TO LEMMA MINOR, PIMEPHALES PROMELA, DAPHNIA MAGNA, AND CERIODAPHNIA DUBIA

Science.gov (United States)

The research presented here resulted in EC50 and LOEC values for the contaminants copper, cadmium, diazinon, atrazine, and cyanide to the species Lemna Minor, Pimephales promelas, Daphnia magna, and Ceriodaphnia dubia. Observed values were used as benchmarks for assessing the se...

Gas chromatography-mass spectrometry of N-heptafluorobutyryl isobutyl esters of amino acids in the analysis of the kinetics of [15N]H4+ assimilation in Lemna minor L

International Nuclear Information System (INIS)

Rhodes, D.; Myers, A.C.; Jamieson, G.

1981-01-01

Rapid, sensitive, and selective methods for the determination of the 15 N abundance of amino acids in isotopic tracer experiments with plant tissues are described and discussed. Methodology has been directly tested in an analysis of the kinetics of [ 15 N]H 4 + assimilation in Lemna minor L. The techniques utilize gas chromatography-mass spectrometry selected ion monitoring of major fragments containing the N moiety of N-heptafluorobutyryl isobutyl esters of amino acids. The ratio of selected ion pairs at the characteristic retention time of each amino acid derivative can be used to calcuulate 15 N abundance with an accuracy of +/- 1 atom % excess 15 N using samples containing as little as 30 picomoles of individual amino acids. Up to 11 individual amino acid derivatives can be selectively monitored in a single chromatogram of 30 minutes. It is suggested that these techniques will be useful in situations where the small quantities of N available for analysis have hitherto hindered the use of 15 N-labeled precursors

Monte Carlo investigation of minority electron transport in InP

International Nuclear Information System (INIS)

Osman, M.A.; Grubin, H.L.

1989-01-01

This paper discusses the investigation of the transport of minority electrons in p-type InP for acceptor doping level of 10 18 cm 3 using Monte Carlo procedures. It is found that the velocity of minority electrons are significantly lower than that of majority electrons for fields below 15 kV/cm and slightly higher at higher fields. The study shows that the interaction between the electrons and majority holes leads to reducing the mobility of electrons from 2000 cm 2 /Vs to 1500 cm 2 /Vs

Exposure to radiofrequency radiation induces oxidative stress in duckweed Lemna minor L

Energy Technology Data Exchange (ETDEWEB)

Tkalec, Mirta [Department of Botany, Division of Biology, Faculty of Science, University of Zagreb, Rooseveltov trg 6, HR-10000 Zagreb (Croatia)], E-mail: mtkalec@zg.biol.pmf.hr; Malaric, Kresimir [Faculty of Electrical Engineering and Computing, University of Zagreb, Unska 3, HR-10000 Zagreb (Croatia); Pevalek-Kozlina, Branka [Department of Botany, Division of Biology, Faculty of Science, University of Zagreb, Rooseveltov trg 6, HR-10000 Zagreb (Croatia)

2007-12-15

Widespread use of radiofrequency radiation emitting devices increased the exposure to electromagnetic fields (EMFs) from 300 MHz to 300 GHz. Various biological effects of exposure to these fields have been documented so far, but very little work has been carried out on plants. The aim of the present work was to investigate the physiological responses of the plant Lemna minor after exposure to radiofrequency EMFs, and in particular, to clarify the possible role of oxidative stress in the observed effects. Duckweed was exposed for 2 h to EMFs of 400 and 900 MHz at field strengths of 10, 23, 41 and 120 V m{sup -1}. The effect of a longer exposure time (4 h) and modulation was also investigated. After exposure, parameters of oxidative stress, such as lipid peroxidation, H{sub 2}O{sub 2} content, activities and isoenzyme pattern of antioxidative enzymes as well as HSP70 expression were evaluated. At 400 MHz, lipid peroxidation and H{sub 2}O{sub 2} content were significantly enhanced in duckweed exposed to EMFs of 23 and 120 V m{sup -1} while other exposure treatments did not have an effect. Compared to the controls, the activities of antioxidative enzymes showed different behaviour: catalase (CAT) activity increased after most exposure treatments while pyrogallol (PPX) and ascorbate peroxidase (APX) activities were not changed. Exceptions were reduced PPX and APX activity after longer exposure at 23 V m{sup -1} and increased PPX activity after exposures at 10 and 120 V m{sup -1}. By contrast, at 900 MHz almost all exposure treatments significantly increased level of lipid peroxidation and H{sub 2}O{sub 2} content but mostly decreased PPX activity and did not affect CAT activity. Exceptions were exposures to a modulated field and to the field of 120 V m{sup -1} which increased PPX and CAT activity. At this frequency APX activity was significantly decreased after exposure at 10 V m{sup -1} and longer exposure at 23 V m{sup -1} but it increased after a shorter exposure at

Exposure to radiofrequency radiation induces oxidative stress in duckweed Lemna minor L

International Nuclear Information System (INIS)

Tkalec, Mirta; Malaric, Kresimir; Pevalek-Kozlina, Branka

2007-01-01

Widespread use of radiofrequency radiation emitting devices increased the exposure to electromagnetic fields (EMFs) from 300 MHz to 300 GHz. Various biological effects of exposure to these fields have been documented so far, but very little work has been carried out on plants. The aim of the present work was to investigate the physiological responses of the plant Lemna minor after exposure to radiofrequency EMFs, and in particular, to clarify the possible role of oxidative stress in the observed effects. Duckweed was exposed for 2 h to EMFs of 400 and 900 MHz at field strengths of 10, 23, 41 and 120 V m -1 . The effect of a longer exposure time (4 h) and modulation was also investigated. After exposure, parameters of oxidative stress, such as lipid peroxidation, H 2 O 2 content, activities and isoenzyme pattern of antioxidative enzymes as well as HSP70 expression were evaluated. At 400 MHz, lipid peroxidation and H 2 O 2 content were significantly enhanced in duckweed exposed to EMFs of 23 and 120 V m -1 while other exposure treatments did not have an effect. Compared to the controls, the activities of antioxidative enzymes showed different behaviour: catalase (CAT) activity increased after most exposure treatments while pyrogallol (PPX) and ascorbate peroxidase (APX) activities were not changed. Exceptions were reduced PPX and APX activity after longer exposure at 23 V m -1 and increased PPX activity after exposures at 10 and 120 V m -1 . By contrast, at 900 MHz almost all exposure treatments significantly increased level of lipid peroxidation and H 2 O 2 content but mostly decreased PPX activity and did not affect CAT activity. Exceptions were exposures to a modulated field and to the field of 120 V m -1 which increased PPX and CAT activity. At this frequency APX activity was significantly decreased after exposure at 10 V m -1 and longer exposure at 23 V m -1 but it increased after a shorter exposure at 23 V m -1 . At both frequencies no differences in isoenzyme

浮萍饲喂黄粉虫的效益分析%Effects and profits of feeding Tenebrio molitor with Lemna minor

Institute of Scientific and Technical Information of China (English)

郑燕玲; 赖锦洪; 杨靖; 谢思; 羊海军

2015-01-01

以传统饲料配方为对照,测试添加不同用量浮萍(Lemna minor)对黄粉虫(Tenebrio molitor)幼虫生长发育及蛋白、粗脂肪含量等指标的影响.结果表明,黄粉虫幼虫对新鲜浮萍适口性良好;新鲜浮萍投饲比例大于80％,对黄粉虫幼虫的生长发育有阻滞,但对其蛋白、粗脂肪含量无显著影响(P＞0.05);以鲜浮萍∶麦麸质量百分比为65％∶35％配置,可使饲料成本降低33.95％,且不影响黄粉虫的饲喂周期、产量和质量.利用新鲜浮萍饲喂黄粉虫幼虫是可行的,通过构建“浮萍-黄粉虫”食物链,可显著降低养殖成本,增加经济效益和生态效益,促进黄粉虫养殖行业发展.

Caracterización molecular por patrones electroforéticos de isoenzimas esterasas en Lemna aequinoctialis y Lemna valdiviana (lemnaceae de Costa Rica (ING

Directory of Open Access Journals (Sweden)

Sharon Jiménez Delgado

2016-03-01

Full Text Available The Lemnaceae family lacks morphologic and anatomical characteristics with comparative aims and for that reason the molecular studies has been necessary a differentiation. In Costa Rica there are two species of Lemna: Lemna aequinoctialis and Lemna valdiviana. With the objective of a molecular characterization and differentiation of both species were extracted isoenzymes esterases. The study was carried out in the Molecular Genetics Laboratory of the School of Biological Sciences at Universidad Nacional, Heredia, Costa Rica. The technical electrophoresis in gel of polyacrylamida SDS-PAGE was used. It was difference in the pattern of isoenzymes between both species. According to previous molecular studies based on morphology and anatomy, flavonoides, isoenzymes, and DNA sequences of certain genes both species are very different; in addition they belong to different monophyletics groups. On the other hand, the importance of this molecular characterization is its possible use in water treatment, because the esterases have had important in the bioremediation. Also, species of the Lemnaceae family are used in the water treatment like bioremediation.

Responses of antioxidant systems after exposition to rare earths and their role in chilling stress in common duckweed (Lemna minor L.): a defensive weapon or a boomerang?

Science.gov (United States)

Ippolito, M P; Fasciano, C; d'Aquino, L; Morgana, M; Tommasi, F

2010-01-01

Extensive agriculture application of rare earth elements (REEs) in Far East countries might cause spreading of these metals in aquatic and terrestrial ecosystems, thus inducing a growing concern about their environmental impact. In this work the effects of a mix of different REE nitrate (RE) and of lanthanum nitrate (LA) on catalase and antioxidant systems involved in the ascorbate-glutathione cycle were investigated in common duckweed Lemna minor L. The results indicated that L. minor shows an overall good tolerance to the presence of REEs in the media. Treatments at concentrations up to 5 mM RE and 5 mM LA did not cause either visible symptoms on plants or significant effects on reactive oxygen species (ROS) production, chlorophyll content, and lipid peroxidation. Toxic effects were observed after 5 days of exposition to 10 mM RE and 10 mM LA. A remarkable increase in glutathione content as well as in enzymatic antioxidants was observed before the appearance of the stress symptoms in treated plants. Duckweed plants pretreated with RE and LA were also exposed to chilling stress to verify whether antioxidants variations induced by RE and LA improve plant resistance to the chilling stress. In pretreated plants, a decrease in ascorbate and glutathione redox state and in chlorophyll content and an increase in lipid peroxidation and ROS production levels were observed. The use of antioxidant levels as a stress marker for monitoring REE toxicity in aquatic ecosystems by means of common duckweed is discussed.

Application of a new sediment contact test with Myriophyllum aquaticum and of the Aquatic Lemna test to assess the sediment quality of Lake Skadar

Energy Technology Data Exchange (ETDEWEB)

Stesevic, D.; Sundic, D.; Mijovic, S. [Montenegro Univ., Podgorica (ME). Faculty of Sciences; Feiler, U.; Heininger, P. [Federal Institute of Hydrology, Koblenz (Germany); Erdinger, L. [Heidelberg Univ. (Germany). Inst. of Hygiene; Seiler, T.B.; Hollert, H. [Heidelberg Univ. (Germany). Dept. of Zoology; RWTH Aachen (Germany). Inst. fuer Umweltforschung - Biologie V

2007-10-15

Goal, Scope and Background: Situated in the transboundary belt between Montenegro and Albania, the Lake Skadar is the largest freshwater reservoir in Southeastern Europe. Because of the wide range of endemic, rare or endangered plant and animal species it supports, Lake Skadar and its extensive adjacent wetlands are internationally recognised as a site of significance and importance (Ramsar site). Within the last 10 to 20 years, Lake Skadar was exposed to intensive pollution. For the assessment of the ecotoxic load of the sediments sampled in Lake Skadar, a triad approach was recently applied. Overall, a complex spectrum of ecotoxic loads was elucidated. The aim of the present study was to use plant-based bioassays for assessing the sediment quality of Lake Skadar in order to facilitate and complement the triad test battery. The newly developed sediment contact test with Myriophyllum aquaticum and the aquatic growth inhibition test with Lemna minor were applied to native sediments and pore water, respectively, allowing the investigation of different toxicity-effects caused by particle-bound pollutants as well as pollutants in the interstitial water. This investigation is the first application of the novel sediment contact test with Myriophyllum aquaticum to lake sediments. Materials and Methods: Sediment samples were taken from nine selected sites at Lake Skadar and investigated by the sediment contact assay with Myriophyllum aquaticum. The pore water was extracted from these sediment samples to be analysed in the aquatic growth inhibition test with Lemna minor. The results of the sediment contact tests were compared with each other and with those of the aquatic growth inhibition test. Results and Discussion: Both applied macrophyte biotests revealed distinct changes in the growth behaviour of the two macrophytes subsequent to the exposure to the investigated natural sediments of Lake Skadar. The Myriophyllum sediment contact test revealed significant toxicity in

The first toxicological study of the antiozonant and research tool ethylene diurea (EDU) using a Lemna minor L. bioassay: Hints to its mode of action.

Science.gov (United States)

Agathokleous, Eugenios; Mouzaki-Paxinou, Akrivi-Chara; Saitanis, Costas J; Paoletti, Elena; Manning, William J

2016-06-01

The antiozonant and research tool ethylene diurea (EDU) is widely studied as a phytoprotectant against the widespread pollutant ground-surface ozone. Although it has been extensively used, its potential toxicity in the absence of ozone is unknown and its mode of action is unclear. The purpose of this research was to toxicologically assess EDU and to further investigate its mode of action using Lemna minor L. as a model organism. Application of EDU concentrations greater than 593 mg L(-1) (practically 600 mg L(-1)) resulted in adverse inhibition of colony growth. As no-observed-toxic-effects concentration (NOEL) we recommend a concentration of 296 mg L(-1) (practically 300 mg L(-1)). A hormetic response was detected, i.e. stimulatory effects of low EDU concentrations, which may indicate overcompensation in response to disruption in homeostasis. Growth inhibition and suppressed biomass were associated with impacted chlorophyll a fluorescence (ΦPSII, qP and ETR). Furthermore, EDU increased mesophyll thickness, as indicated by frond succulence index. Applications of concentrations ≥593 mg L(-1) to uncontrolled environments should be avoided due to potential toxicity to sensitive organisms and the environment. Copyright © 2016 Elsevier Ltd. All rights reserved.

Land spreading of sewage sludge in forest plantations: effects on the growth of the duckweed Lemna minor and trace metal bioaccumulation in the snail Cantareus aspersus.

Science.gov (United States)

Mohamed, Bourioug; Frédéric, Gimbert; Laurence, Alaoui-Sehmer; Pierre-Marie, Badot; Badr, Alaoui-Sossé; Lotfi, Aleya

2016-05-01

Wastewater plants generated annually millions of tons of sewage sludge (SS). Large amounts of this organic residue are spread on agricultural lands as a fertilizer, although it is viewed as a major potential source of contamination, presenting a danger to the terrestrial and aquatic environments. This study was undertaken to evaluate the impact of this practice on the duckweed Lemna minor and the snail Cantareus aspersus. Sludge was applied to soil either at six different loading rates equal to 0, 0.4, 3, 10, 30, and 60 tons dry matter (DM) ha(-1) for L. minor test or at three rates equal to 0, 30, and 60 tons DM ha(-1) for C. aspersus test. At the highest rate of SS application (60 tons DM ha(-1)), the eluates showed that an increase in pH (6.1) resulted in a decrease in Al levels. Thus, the high stimulation of L. minor growth observed after this high rate of SS application can be explained by (i) a reduction in Al toxicity after precipitation and (ii) macro- and micronutrient enrichment. At a rate of SS application of only 30 tons DM ha(-1), growth appeared to be slightly significant (p < 0.05), in spite of the significant increase in essential mineral elements. However, it is very difficult to discriminate between Al toxicity and pH effects. For the test with C. aspersus, the snail biomass was not affected by sludge application over the exposure period. Mortality was extremely low, with a rate of less than 4 % at the last sampling date. Yet, Cu, Pb, and Cd accumulated significantly in the soft body of snails exposed to SS application, suggesting that the amount of metals excreted is lower than that absorbed. In contrast, Zn levels remain constant, inferring that absorption and elimination of Zn are balanced at the beginning of the experiment.

Removal of 99mTc and 201Tl by means of Lemna Gibba

International Nuclear Information System (INIS)

Fernandez R, E.; Carreno de L, M. C.; Cuevas S, J. C.; Hernadez T, U. O.; Monroy G, F.

2012-10-01

In this work the capacity of the water macrophyte Lemna gibba coming from San Pedro Tultepec in the Mexico State was studied to remove the radioisotopes 99m Tc and 201 Tl, in order to show the capacity of this macrophyte for to treat some radioactive waste flowing that could contain this radioisotopes type. The removal capacity of 99m Tc and 201 Tl of the macrophyte Lemna gibba was determined using the batch method. In accordance with the values of the obtained K d , the Lemna gibba with a size of particle diameter among 1mm - 300 μm presents a better adsorption of 99m Tc. The 201 Tl is adsorbed better in the bioadsorbent when it has a size of particle diameter <150μm. (Author)

DAMAGE TO DNA PRIMARY STRUCTURE AND ANTIOXIDANT ENZYMES IN LEMNA MINOR INDUCED BY HG2+%Hg2+ 胁迫对浮萍体细胞DNA一级结构和抗氧化酶系的损伤

Institute of Scientific and Technical Information of China (English)

徐楠; 施国新; 曾晓敏; 丁小余; 徐勤松; 陈源

2003-01-01

主要从DNA一级结构及抗氧化酶系变化两方面,研究了Hg2+胁迫下浮萍体细胞的损伤.结果表明:运用随机扩增多态性DNA法(Random amplified polymorphism DNA, RAPD)和DNA梯法(DNA Ladder),5～10 mg*L-1 Hg2+处理组可检测到基因组DNA的明显损伤,20 mg*L-1Hg2+已导致细胞坏死;RAPD法较DNA Ladder法更灵敏.本文还发现,活性氧和抗氧化酶系很可能参与了浮萍体细胞凋亡过程.低浓度的Hg2+胁迫可刺激抗氧化酶活性升高,以清除体内活性氧,而一旦活性氧水平超出一定域值,抗氧化酶活性急速下降,导致细胞凋亡.%The damage to Lemna minor cells induced by Hg2+ was studied in this article. Most damage occurred to DNA primary structure and changes in antioxidant enzyme activities were investigated by using RAPD and DNA ladder methods. The results showed that obvious damage to DNA was found in the process of apoptosis induced by 5-10 mg*L-1 Hg2+, and 20 mg*L-1 Hg2+ had already caused necrotic injury. The RAPD method was the more sensitive of the two methods, and so could be considered as an important method for monitoring apoptosis. The results also indicated that reactive oxygen species (ROS) and antioxidant enzymes are involved in the process of apoptosis. The activities of antioxidant enzymes could be stimulated to eliminate active oxygen by exposing the Lemna minor to low Hg2+ concentration; the cells declined rapidly when ROS were unable to be eliminated effectively.

Dwergkroos (Lemna minuscula Herter) nieuw voor Nederland

NARCIS (Netherlands)

Schaminée, Joop H.J.; Hermans, Jan T.

1989-01-01

Lemna minuscula was found for the first time in the Netherlands in the Meggelveld area, a complex of claypits in Central Limburg. This American species, in Europe first recorded in southern France in 1966, is expanding its area to the north and east. The habitat and growth form in the Meggelveld

Common Duckweed (Lemna minor) Is a Versatile High-Throughput Infection Model For the Burkholderia cepacia Complex and Other Pathogenic Bacteria

Science.gov (United States)

Thomson, Euan L. S.; Dennis, Jonathan J.

2013-01-01

Members of the Burkholderia cepacia complex (Bcc) have emerged in recent decades as problematic pulmonary pathogens of cystic fibrosis (CF) patients, with severe infections progressing to acute necrotizing pneumonia and sepsis. This study presents evidence that Lemna minor (Common duckweed) is useful as a plant model for the Bcc infectious process, and has potential as a model system for bacterial pathogenesis in general. To investigate the relationship between Bcc virulence in duckweed and Galleria mellonella (Greater wax moth) larvae, a previously established Bcc infection model, a duckweed survival assay was developed and used to determine LD50 values. A strong correlation (R2 = 0.81) was found between the strains’ virulence ranks in the two infection models, suggesting conserved pathways in these vastly different hosts. To broaden the application of the duckweed model, enteropathogenic Escherichia coli (EPEC) and five isogenic mutants with previously established LD50 values in the larval model were tested against duckweed, and a strong correlation (R2 = 0.93) was found between their raw LD50 values. Potential virulence factors in B. cenocepacia K56-2 were identified using a high-throughput screen against single duckweed plants. In addition to the previously characterized antifungal compound (AFC) cluster genes, several uncharacterized genes were discovered including a novel lysR regulator, a histidine biosynthesis gene hisG, and a gene located near the gene encoding the recently characterized virulence factor SuhBBc. Finally, to demonstrate the utility of this model in therapeutic applications, duckweed was rescued from Bcc infection by treating with bacteriophage at 6-h intervals. It was observed that phage application became ineffective at a timepoint that coincided with a sharp increase in bacterial invasion of plant tissue. These results indicate that common duckweed can serve as an effective infection model for the investigation of bacterial virulence

Alleviation of cadmium toxicity in Lemna minor by exogenous salicylic acid.

Science.gov (United States)

Lu, Qianqian; Zhang, Tingting; Zhang, Wei; Su, Chunlei; Yang, Yaru; Hu, Dan; Xu, Qinsong

2018-01-01

Cadmium (Cd) is a significant environmental pollutant in the aquatic environment. Salicylic acid (SA) is a ubiquitous phenolic compound. The goal of this study was to assess the morphological, physiological and biochemical changes in duckweed (L. minor) upon exposure to 10μM CdCl 2 , 10μM CdCl 2 plus 50μM SA, or 50μM SA for 7 days. Reversing the effects of Cd, SA decreased Cd accumulation in plants, improved accumulation of minerals (Ca, Mg, Fe, B, Mo) absorption, increased endogenous SA concentration, and phenylalanine ammonialyase (PAL) activity. Chlorosis-associated symptoms, the reduction in chlorophyll content, and the overproduction of reactive oxygen species induced by Cd exposure were largely reversed by SA. SA significantly decreased the toxic effects of Cd on the activities of the superoxide dismutase, peroxidase, catalase, ascorbate peroxidase, and glutathione reductase in the fronds of L. minor. Furthermore, SA reversed the detrimental effects of Cd on total ascorbate, glutathione, the ascorbic acid/oxidized dehydroascorbate and glutathione/glutathione disulphide ratios, lipid peroxidation, malondialdehyde concentration, lipoxygenase activity, and the accumulation of proline. SA induced the up-regulation of heat shock proteins (Hsp70) and attenuated the adverse effects of Cd on cell viability. These results suggest that SA confers tolerance to Cd stress in L. minor through different mechanisms. Copyright © 2017 Elsevier Inc. All rights reserved.

Comparison of gamma- and beta radiation stress responses on anti-oxidative defense system and DNA modifications in Lemna minor

Energy Technology Data Exchange (ETDEWEB)

Van Hoeck, Arne [SCK.CEN, Boeretang 200 2400 Mol (Belgium); University of Antwerp, Groenenborgerlaan 171, 2020 Antwerpen (Belgium); Horemans, Nele; Van Hees, May; Nauts, Robin; Vandenhove, Hildegarde [SCK.CEN, Boeretang 200 2400 Mol (Belgium); Knapen, Dries; Blust, Ronny [University of Antwerp, Groenenborgerlaan 171, 2020 Antwerpen (Belgium)

2014-07-01

The biological effects and interactions of different radiation types in plants are still far from understood. Additional knowledge on the impact of various kinds of ionizing radiation in plants on individual, biochemical and molecular level is needed to unravel and compare the toxic mode of action. Among different radiation types, external gamma radiation treatments have been mostly studied both in lab and field studies to derive the biological impact of radiation toxicity in organisms. However, environmental relevant studies on chronic low-dose gamma exposures are scarce. The radio-ecologically relevant radionuclide {sup 90}Sr is a pure beta emitting isotope and originates from nuclear activities and accidents. Although this radionuclide is not essential for plant metabolism, it bears a chemical analogy with the essential plant macro-nutrient Ca{sup 2+} thereby taking advantage of Ca{sup 2+} transport systems to contaminate plant organs and tissues. Ones plants are exposed to radiation stress, ionization events can cause an increase in reactive oxygen species (ROS) and can induce damage to biological material like DNA, lipids and structural proteins. The following work aimed at evaluating individual, biochemical and molecular endpoints to understand and to compare the mode of action of gamma- and beta radiation stress in plants. Having an equal relative biological effectiveness to non-human biota, it is still not clear in how plants differ or overlap in sensing and interpreting highly penetrating electromagnetic radiation with short-range particle radiation. The floating plant Lemna minor was chosen as model system. Following the OECD guidelines Lemna plants were being exposed separately to an external gamma radiation source or to a {sup 90}Sr-contaminated growth medium to obtain single-dose response curves for each type of radiation. In order to acquire accurate dose rate quantifications for beta radiation exposures, {sup 90}Sr uptake and accumulation of root and

Swelling and Degradation of Calcium-Pectic Gel Particles Made of Pectins of Silene vulgaris and Lemna minor Сallus Cultures at Different Concentrations of Pectinase in an Artificial Colon Environment

Directory of Open Access Journals (Sweden)

Anatoly A. Shubakov

2018-03-01

Full Text Available Spherical calcium-pectic gel particles (CaPGPs were obtained from pectins of callus cultures (CC of campion Silene vulgaris (silenan and duckweed Lemna minor (lemnan, as well as from commercial apple and citrus pectins by the method of ionotropic gelation. We studied the morphological characteristics of the obtained gel particles and found that the largest gel particles were formed from citrus pectin (CP, and the densest gel particles were formed from lemnan pectin (LP. The swelling and degradation of CaPGPs were comparatively evaluated by incubation in a simulated gastrointestinal environment. The swelling and degradation of CaPGPs formed from pectins of the silenan and lemnan callus cultures were studied at different concentrations of pectinase (0.4, 0.8 and 1.7 mg/ml in the simulated fluid of the colon. It has been established that the CaPGPs obtained from lemnan are more resistant to degradation in the simulated colon fluid than CaPGP obtained from silenan. It was shown that the concentration of pectinase in the simulated fluid of the colon and the type of pectin affect the degradability of CaPGPs formed on the basis of pectins of callus cultures.

Phytotechnology Technical and Regulatory Guidance and Decision Trees, Revised

Science.gov (United States)

2009-02-01

Anderson, Guthrie, and Walton 1993 Demeton-8- methyl Duckweed ( Lemna minor ) PE, PD Approximately 10% total transformation (PE and PD) measured in 48...Duckweed ( Lemna minor ) PE, PD Approximately 25% total transformation (PE and PD) measured in 24 hours Gao et al. 1998 Malathion Parrot feather...in 14 days Anderson, Kruger, and Coats 1994 Metolachor Duckweed ( Lemna minor ) PE 25% remaining in the water after 16 days Rice, Anderson, and

镉和乙草胺单一及复合污染对浮萍生长的影响%Effects of Single and Combined Pollution of Cadmium and Acetochlor on the Growth of Lemna minor L.

Institute of Scientific and Technical Information of China (English)

黄河; 姜萍萍

2011-01-01

[目的]研究镉和乙草胺单一及复合污染对浮萍生长的影响.[方法]采用室内培养的方法,研究了镉和乙草胺单一及复合污染对浮萍生物量(鲜重)、叶绿素含量、可溶性糖含量、游离脯氨酸含量和丙二醛(MDA)含量的影响.[结果]在镉和乙草胺单一及复合污染条件下,浮萍的鲜重和叶绿素含量在处理后第5天显著下降,且随处理时间的延长,下降趋势更明显；可溶性糖含量在处理后第5天增加近29％,但在处理后第10和15天,随处理浓度的增加可溶性糖含量下降了近23％和28％；而脯氨酸和丙二醛含量随处理浓度的增加而显著增加.[结论]复合污染加剧了对浮萍的毒害作用.%[Objective ] The aim was to study the effects of cadmium ( Cd ) and acetochlor ( AC ) on Lemna minar L. Growth. [ Method ] Hydroponics culture experiments were conducted with Lemna minar L. In room, the single and joint toxic effects of cadmium and acetochlor on the biomass (fresh weight) , chlorophyll, soluble sugar, free praline, and malondialdehyde( MDA) contents in the leaves of Lemna minor L. Were studied. [ Result] The results showed that under the condition of single and combined pollution,the biomass were decreased significantly as compared to the control after 5 days treatment,and decreased more significantly with the time; the soluble sugar content increased by 29% after 5 days treatment,but then decreased by 23% and 28% .after 10 days and 15 days treatment respectively. The free proline and MDA content were increased significantly with the concentration. [ Conclusion] The results showed shown that the effects of combined pollution were heavier than those of single pollution.

Common duckweed (Lemna minor is a versatile high-throughput infection model for the Burkholderia cepacia complex and other pathogenic bacteria.

Directory of Open Access Journals (Sweden)

Euan L S Thomson

Full Text Available Members of the Burkholderia cepacia complex (Bcc have emerged in recent decades as problematic pulmonary pathogens of cystic fibrosis (CF patients, with severe infections progressing to acute necrotizing pneumonia and sepsis. This study presents evidence that Lemna minor (Common duckweed is useful as a plant model for the Bcc infectious process, and has potential as a model system for bacterial pathogenesis in general. To investigate the relationship between Bcc virulence in duckweed and Galleria mellonella (Greater wax moth larvae, a previously established Bcc infection model, a duckweed survival assay was developed and used to determine LD50 values. A strong correlation (R(2 = 0.81 was found between the strains' virulence ranks in the two infection models, suggesting conserved pathways in these vastly different hosts. To broaden the application of the duckweed model, enteropathogenic Escherichia coli (EPEC and five isogenic mutants with previously established LD50 values in the larval model were tested against duckweed, and a strong correlation (R(2 = 0.93 was found between their raw LD50 values. Potential virulence factors in B. cenocepacia K56-2 were identified using a high-throughput screen against single duckweed plants. In addition to the previously characterized antifungal compound (AFC cluster genes, several uncharacterized genes were discovered including a novel lysR regulator, a histidine biosynthesis gene hisG, and a gene located near the gene encoding the recently characterized virulence factor SuhB(Bc. Finally, to demonstrate the utility of this model in therapeutic applications, duckweed was rescued from Bcc infection by treating with bacteriophage at 6-h intervals. It was observed that phage application became ineffective at a timepoint that coincided with a sharp increase in bacterial invasion of plant tissue. These results indicate that common duckweed can serve as an effective infection model for the investigation of bacterial

The abundance and diversity of heterotrophic bacteria as a function of harvesting frequency of duckweed (Lemna minor L.) in recirculating aquaculture systems.

Science.gov (United States)

Ardiansyah, A; Fotedar, R

2016-07-01

Duckweed (Lemna minor L.) is a potential biofilter for nutrient removal and acts as a substrate for heterotrophic bacteria in recirculating aquaculture systems (RAS). Here, we determined the effects of harvesting frequency of duckweed on heterotrophic bacteria in RAS. Twelve independent RAS consisting of fish-rearing tank, biofilter tank and waste-collection tank were used to study the interactions between duckweed harvest frequencies up to 6 days and the composition, abundance and diversity of heterotrophic bacteria. After 36 days, heterotrophic bacteria in the biofilter tank were primarily Gram-negative cocci or ovoid, coccobacilli, Gram-negative bacilli and Gram-positive bacilli. Most bacterial genera were Bacillus and Pseudomonas while the least common was Acinetobacter. Duckweed harvested after every 2 days produced the highest specific growth rates (SGR) and total harvested biomass of duckweed, but harboured less abundant bacteria, whereas 6-day harvests had a higher growth index (GI) of duckweed than 2-day harvests, but caused a poor relationship between SGR and biomass harvest with the abundance and diversity of heterotrophic bacteria. Stronger correlations (R(2)  > 0·65) between duckweed SGR and biomass harvest with the heterotrophic bacteria diversity were observed at 4-day harvest frequency and the control. This study provides significant information on the interaction between the harvest frequency of duckweed and the composition, abundance and diversity of heterotrophic bacteria in recirculating aquaculture systems (RAS). Different harvest frequencies significantly influence the abundance and diversity of heterotrophic bacteria, which in turn may influence the nitrogen uptake efficiency of the system. The research is useful in improving the efficiency of removing nitrogenous metabolites in RAS directly by the duckweed and associated heterotrophic bacteria. © 2016 The Society for Applied Microbiology.

The first toxicological study of the antiozonant and research tool ethylene diurea (EDU) using a Lemna minor L. bioassay: Hints to its mode of action

International Nuclear Information System (INIS)

Agathokleous, Eugenios; Mouzaki-Paxinou, Akrivi-Chara; Saitanis, Costas J.; Paoletti, Elena; Manning, William J.

2016-01-01

The antiozonant and research tool ethylene diurea (EDU) is widely studied as a phytoprotectant against the widespread pollutant ground-surface ozone. Although it has been extensively used, its potential toxicity in the absence of ozone is unknown and its mode of action is unclear. The purpose of this research was to toxicologically assess EDU and to further investigate its mode of action using Lemna minor L. as a model organism. Application of EDU concentrations greater than 593 mg L −1 (practically 600 mg L −1 ) resulted in adverse inhibition of colony growth. As no-observed-toxic-effects concentration (NOEL) we recommend a concentration of 296 mg L −1 (practically 300 mg L −1 ). A hormetic response was detected, i.e. stimulatory effects of low EDU concentrations, which may indicate overcompensation in response to disruption in homeostasis. Growth inhibition and suppressed biomass were associated with impacted chlorophyll a fluorescence (Φ PSII , q P and ETR). Furthermore, EDU increased mesophyll thickness, as indicated by frond succulence index. Applications of concentrations ≥593 mg L −1 to uncontrolled environments should be avoided due to potential toxicity to sensitive organisms and the environment. - Highlights: • The EDU concentration of 300 mg L −1 should be considered as NOEL. • EDU concentrations ≥600 mg L −1 should not be applied to uncontrolled environments. • Hormetic responses indicate overcompensation in response to homeostasis disruption. - Ethylene diurea is not toxic to sensitive organisms when applied at low concentrations (practically < 600 mg L −1 ).

Electronic cigarette initiation among minority youth in the United States.

Science.gov (United States)

Hammig, Bart; Daniel-Dobbs, Page; Blunt-Vinti, Heather

2017-05-01

Electronic cigarettes (e-cigarette) use among youth is a pressing public health issue, with prevalence of use surpassing that of tobacco cigarettes. While research concerning e-cigarettes has proliferated in recent years, there is a dearth of information regarding those whose first exposure to tobacco products was an e-cigarette. To examine factors associated with e-cigarette initiation among minority youth in the United States. Data on minority students in middle and high schools in the United States derived from the 2014 National Youth Tobacco Survey (NYTS) were sampled (weighted N = 27,294,454). We examined e-cigarette initiation among minority youth using logistic regression models to identify related factors. In 2014, 736,158 minority youth were e-cigarette initiators. Odds of e-cigarette initiation was highest among Hispanic youth [adjusted odds ratio (AOR) = 2.70; 95% confidence interval (CI) = 1.60-4.56]. Exposure to e-cigarette advertising (AOR = 1.64; 95% CI = 1.07-2.50), perceptions of little to no harm (AOR = 7.08; 95% CI = 4.03-12.46), and believing e-cigarettes were less addictive than tobacco (AOR = 2.15; 95% CI = 1.52-3.02) were associated with e-cigarette initiation. Odds of initiating e-cigarette use was highest among Hispanic youth. Among minority youth, e-cigarette initiation was associated with perceptions of harm and addiction potential, as well as exposure to e-cigarette advertising. Therefore, prevention efforts targeting minority youth who are at risk of becoming e-cigarette initiators may benefit by incorporating these factors into prevention campaigns.

Electronic cigarette sales to minors via the internet.

Science.gov (United States)

Williams, Rebecca S; Derrick, Jason; Ribisl, Kurt M

2015-03-01

Electronic cigarettes (e-cigarettes) entered the US market in 2007 and, with little regulatory oversight, grew into a $2-billion-a-year industry by 2013. The Centers for Disease Control and Prevention has reported a trend of increasing e-cigarette use among teens, with use rates doubling from 2011 to 2012. While several studies have documented that teens can and do buy cigarettes online, to our knowledge, no studies have yet examined age verification among Internet tobacco vendors selling e-cigarettes. To estimate the extent to which minors can successfully purchase e-cigarettes online and assess compliance with North Carolina's 2013 e-cigarette age-verification law. In this cross-sectional study conducted from February 2014 to June 2014, 11 nonsmoking minors aged 14 to 17 years made supervised e-cigarette purchase attempts from 98 Internet e-cigarette vendors. Purchase attempts were made at the University of North Carolina Internet Tobacco Vendors Study project offices using credit cards. Rate at which minors can successfully purchase e-cigarettes on the Internet. Minors successfully received deliveries of e-cigarettes from 76.5% of purchase attempts, with no attempts by delivery companies to verify their ages at delivery and 95% of delivered orders simply left at the door. All delivered packages came from shipping companies that, according to company policy or federal regulation, do not ship cigarettes to consumers. Of the total orders, 18 failed for reasons unrelated to age verification. Only 5 of the remaining 80 youth purchase attempts were rejected owing to age verification, resulting in a youth buy rate of 93.7%. None of the vendors complied with North Carolina's e-cigarette age-verification law. Minors are easily able to purchase e-cigarettes from the Internet because of an absence of age-verification measures used by Internet e-cigarette vendors. Federal law should require and enforce rigorous age verification for all e-cigarette sales as with the federal

Biosolubilization of uranyl ions in uranium ores by hydrophyte plants

International Nuclear Information System (INIS)

Cecal, Alexandru; Calmoi, Rodica; Melniciuc-Puica, Nicoleta

2006-01-01

This paper investigated the bioleaching of uranyl ions from uranium ores, in aqueous medium by hydrophyte plants: Lemna minor, Azolla caroliniana and Elodea canadensis under different experimental conditions. The oxidation of U(IV) to U(VI) species was done by the atomic oxygen generated in the photosynthesis process by the aquatic plants in the solution above uranium ores. Under identical experimental conditions, the capacity of bioleaching of uranium ores decreases according to the following series: Lemna minor > Elodea canadensis > Azolla caroliniana. The results of IR spectra suggest the possible use of Lemna minor and Elodea canadensis as a biological decontaminant of uranium containing wastewaters. (author)

镧、锌及其交互作用对浮萍活性氧清除系统的影响%Effect of interaction of La and Zn on the reactive oxygen scavenging system in leaves of Lemna minor

Institute of Scientific and Technical Information of China (English)

马广岳; 施国新; 王学; 徐勤松; 王贵民; Rafeek Khaled

2004-01-01

以浮萍(Lemna minor)为材料,研究La、Zn及其交互作用对体内活性氧清除系统的影响,单独施加20 mg·L-1的La或Zn对浮萍都有明显的伤害作用,且Zn的毒性远大于La.La、Zn复合处理不同程度地减弱各自的毒性,表现为植株叶绿素含量、蛋白质含量及过氧化氢酶(CAT)活性下降减缓;谷胱甘肽(GSH)、抗坏血酸(AsA)含量提高;超氧化物歧化酶(SOD)活性增强;过氧化物酶(POD)活性降低.各处理对浮萍的毒性由大到小的顺序依次为:Zn、La、Zn+La.

Phytotoxic activity of the methanol leaves extract of Paullinia pinnata ...

African Journals Online (AJOL)

The activity of the extract against the growth of Lemna minor was used to investigate the phytotoxic activity. The activity of the methanol extract of P. pinnata leaves against Lemna minor increased in a dose- dependent manner and was significant at 1000 μg/ml. Therefore, the methanol leaves extract of P. pinnata exhibited ...

Полисахариды из каллусной культуры Lemna minor L

OpenAIRE

Гюнтер, Е.

2001-01-01

Целью настоящей работы была общая химическая характеристика полисахаридов, выделенных из каллусной культуры Lemna minor L. Полисахариды каллуса L. minor представляют собой нейтральный и кислый арабиногалактаны, пектин. В состав углеводной цепи пектина входят остатки галактуроновой кислоты (66%), арабинозы и галактозы в качестве основных компонентов....

UV-B辐射和蒽共同作用对三叶浮萍的毒性效应%Joint Toxic Effects of UV-B Radiation and Anthracene on Lemna Minor

Institute of Scientific and Technical Information of China (English)

张攀; 王仁君; 周晶; 沙未来

2012-01-01

本实验采用常见的三叶浮萍作为实验材料,研究了多环芳烃( PAHs)蒽(Anthracene)与UV-B辐射单独胁迫和共同作用对浮萍(Lemna minor)的毒性效应.浮萍的初始个数为45个,蒽的质量浓度分别设为0、0.5、2.5、5、10、20mg·L-1,设计三个个平行组,每组辐射剂量均是810 J·m-2.结果表明,蒽、紫外线单独胁迫都会对浮萍产生损害,使其生长量有下降趋势.当辐射剂量达到810 J·m-2时,叶绿素含量达到最大,随着辐射剂量的增加,叶绿素含量减少.且随着蒽浓度的不断增大,对浮萍生长的其抑制作用更加明显,存在着明显的剂量-效应关系.蒽和UV-B辐射共同作用对浮萍产生抑制作用,并且随着蒽浓度的增加,抑制作用逐渐增强.

Oxygen and hydrogen isotope fractionation during cellulose metabolism in Lemna gibba L

International Nuclear Information System (INIS)

Yakir, D.; DeNiro, M.J.

1990-01-01

Lemna gibba L. B3 was grown under heterotrophic, photoheterotrophic, and autotrophic conditions in water having a variety of hydrogen and oxygen isotopic compositions. The slopes of the linear regression lines between the isotopic composition of water and leaf cellulose indicated that under the three growth conditions about 40, 70, and 100% of oxygens and carbon-bound hydrogens of cellulose exchanged with those of water prior to cellulose formation. Using the equations of the linear relationships, we estimated the overall fractionation factors between water and the exchanged oxygen and carbon bound-hydrogen of cellulose. At least two very different isotope effects must determine the hydrogen isotopic composition of Lemna cellulose. One reflects the photosynthetic reduction of NADP, while the second reflects exchange reactions that occur subsequent to NADP reduction. Oxygen isotopic composition of cellulose apparently is determined by a single type of exchange reaction with water. Under different growth conditions, variations in metabolic fluxes affect the hydrogen isotopic composition of cellulose by influencing the extent to which the two isotope effects mentioned above are recorded. The oxygen isotopic composition of cellulose is not affected by such changes in growth conditions

Duckweed does not improve the efficiency of municipal wastewater treatment in lemna system plants / Rzęsa nie poprawia efektywności oczyszczania ścieków komunalnych w oczyszczalniach typu Lemna System

Directory of Open Access Journals (Sweden)

Ozimek Teresa

2015-09-01

Full Text Available Badania prowadzono w trzech czyszczalniach hydrofi towych z powierzchniowym przepływem ścieków typu Lemna System, zbudowanych według projektu Lemna Corporation. Składają się one ze stawu napowietrzanego i stawu rzęsowego wyposażonego w system barier mających na celu równomierne rozmieszczenie roślin. Stawy poprzedzone są osadnikiem wstępnym. Według projektantów odpowiednia praca tych oczyszczalni związana jest z występowaniem rzęsy na powierzchni stawu rzęsowego. Badano efektywność oczyszczania ścieków komunalnych w trzech oczyszczalniach Lemna System usytuowanych w centralnej Polsce ze szczególnym uwzględnieniem roli stawu rzęsowego i samej rzęsy. Oczyszczalnie różniły się między sobą występowaniem rzęsy. W dwóch z nich (w Rakowie i Bąkowcu w trakcie całego okresu badań rzęsa nie występowała, natomiast w trzeciej (w Falęcinie Starym w okresie wegetacyjnym pokrywała do 90%.powierzchni stawu. Efektywność oczyszczanie ścieków nie różniła się w oczyszczalni z rzęsą i bez rzęsy. Rzęsa nie wpływała istotnie na efektywność oczyszczania ścieków. We wszystkich oczyszczalniach główną rolę w redukcji zanieczyszczeń odgrywał staw napowietrzany

利用稻田养萍诱集控制福寿螺危害的效应研究%Decoy effect of duckweed Lemna minor on Pomacea canaliculata in rice from paddy fields

Institute of Scientific and Technical Information of China (English)

郭靖; 章家恩; 张春霞; 项瑶

2016-01-01

利用自制的“T形槽”进行实验室试验,研究了福寿螺(Pomacea canaliculata)对浮萍(Lemna minor)和不同日龄水稻(Oryza sativa)的偏好选择,结果发现,无论水稻日龄是15d,还是23 d和30 d,均有60％以上的福寿螺选择取食浮萍,且与福寿螺个体大小和选择取食的时间没有明显关联.在模拟稻田生境中,引入浮萍3d后,水稻受福寿螺的啃食危害明显减少,水稻存活率高出对照组10％以上,且30日龄水稻秧苗的存活率明显高于15日龄处理.在此基础上,分析了不同大小福寿螺与浮萍摄入量的关系.这一结果可为浮萍的合理投放提供参考.研究表明,利用稻田放养浮萍诱集福寿螺取食,可以减少福寿螺对水稻的危害.

Interactions of metal-based engineered nanoparticles with aquatic higher plants: A review of state of current knowledge

CSIR Research Space (South Africa)

Thwala, Melusi

2016-01-01

Full Text Available TiO2). Concentration dependent accumulation of Ti was reported after 7 d exposure of Lemna minor to 0.01-5 mg/L nTiO2 [74]. Approximately an average of 70 mg/kg whole plant Ti was recorded at the highest exposure concentration compared to 0.37 mg... differ between species [72] was support d by the findings of Glenn et al. [45]. Using electron microscopy techniques, Li et al. [74] found agglomerates of nTiO2 adsorbed onto L. minor fronds but no internalisation was evident, and concluded...

78 FR 73787 - Chlorsulfuron; Community Right-to-Know Toxic Chemical Release Reporting

Science.gov (United States)

2013-12-09

... identified as the minor metabolic pathway. No additional information on the absorption, distribution... aquatic plants the toxicity of chlorsulfuron is very high. (Ref. 3). Duckweed (Lemna gibba) was the most... (cell density); 120 hr capricornutum). NOEC = 0.0094 mg/L (cell density). Lemna gibba Freshwater...

EVALUACIÓN DE LA BIOMASA Y MANEJO DE Lemna gibba (LENTEJA DE AGUA) EN LA BAHÍA INTERIOR DEL LAGO TITICACA, PUNO

OpenAIRE

Canales-Gutiérrez, Ángel; Facultad de Ciencias Biológicas UNA PUNO (Perú).

2010-01-01

Uno de los mayores problemas que enfrenta la ciudad de Puno es la presencia de la lenteja de agua (Lemna gibba) en la bahía interior del Lago Titicaca, debido al proceso de eutrofización que sufre a causa del mal tratamiento de las aguas residuales de la ciudad de Puno. Muchas de las estrategias planteadas hasta ahora no han dado resultados positivos en la reducción de la biomasa de Lemna gibba, debido a que estos planes están direccionados a la exterminación de este organismo. En lugar de el...

Bans on electronic cigarette sales to minors and smoking among high school students.

Science.gov (United States)

Abouk, Rahi; Adams, Scott

2017-07-01

Many states have banned electronic cigarette sales to minors under the rationale that using e-cigarettes leads to smoking traditional combustion cigarettes. Such sales bans would be counterproductive, however, if e-cigarettes and traditional cigarettes are substitutes, as bans might push teenagers back to smoking the more dangerous combustion cigarettes. We provide evidence that these sales bans reduce the incidence of smoking conventional cigarettes among high school seniors. Moreover, we provide evidence suggesting that sales bans reduced e-cigarette usage as well. This evidence suggests that not only are e-cigarettes and smoking regular cigarettes positively related and not substitutes for young people, banning retail sales to minors is an effective policy tool in reducing tobacco use. Copyright © 2017 Elsevier B.V. All rights reserved.

Doping dependence and anisotropy of minority electron mobility in molecular beam epitaxy-grown p type GaInP

Energy Technology Data Exchange (ETDEWEB)

Haegel, N. M.; Christian, T.; Norman, A. G.; Mascarenhas, A. [National Renewable Energy Laboratory, Golden, Colorado 80401 (United States); Scandrett, C. [Naval Postgraduate School, Monterey, California 93943 (United States); Misra, Pranob; Liu, Ting; Sukiasyan, Arsen; Pickett, Evan; Yuen, Homan [Solar Junction, Inc., San Jose, California 95131 (United States)

2014-11-17

Direct imaging of minority electron transport via the spatially resolved recombination luminescence signature has been used to determine carrier diffusion lengths in GaInP as a function of doping. Minority electron mobility values are determined by performing time resolved photoluminescence measurements of carrier lifetime on the same samples. Values at 300 K vary from ∼2000 to 400 cm{sup 2}/V s and decrease with increasing doping. Anisotropic diffusion lengths and strongly polarized photoluminescence are observed, resulting from lateral composition modulation along the [110] direction. We report anisotropic mobility values associated with carrier transport parallel and perpendicular to the modulation direction.

Development of a rapid and sensitive battery of bioassays for risk assessment of cyanobacterial microcystin-LR in drinking water of rural water treatment plants, South Africa

CSIR Research Space (South Africa)

Oberholster, Paul J

2009-09-01

Full Text Available minor and Lemna gibba are the most commonly tested species used in numerous studies in first world countries as indi- cator macrophyte species (Marwood et al., 2001). No clear trend exists to the relative sensitivities of the dif- ferent duckweed..., Gu KD, Lam PKA, Yang M, Fong WF (2000). Study on the cytotoxicity of microcystin-LR on cultured cells. Chemosphere, 41: 143-147. Cowgill UM, Milazzo DP, Landenberger BD (1991). The sensitivity of Lemma gibba G-3 and four clones of Lemna minor...

DNA damage and repair in Stylonychia lemnae (Ciliata, Protozoa)

International Nuclear Information System (INIS)

Ammermann, D.

1988-01-01

Irradiation with X rays, UV irradiation after incorporation of bromodeoxyuridine (BU) into the DNA, and cis-platinum (cis-Pt) treatment each cause the loss of micronuclei of Stylonychia lemnae while the macronuclei are not severely affected. The abilities of both nuclei to repair DNA were investigated. Unscheduled DNA synthesis could not be demonstrated after X-ray irradiation, but it was found after treatment with BU/UV and cis-Pt in macro- and micronuclei. The extent of the repair process in the micro- and macronuclei was alike, as indicated by grain counts of [6- 3 H]thymidine-treated cells. One reason for the different sensitivity of both nuclei to DNA-damaging treatment may be the different number of gene copies in the macro- and micronuclei

Optimización de un método analítico para la determinación de mercurio en muestras ambientales por espectrometría UV-Visible

Directory of Open Access Journals (Sweden)

Xiomara Piña

2012-12-01

Full Text Available Dithizone´s colorimetric method was modified and quasi miniaturized for mercury determination in water and Lemna minor and Piaractus brachypomus tissue. Detection limit (4-22µg.L-1 was adequate for environmental studies. Evaluation of the accuracy in water was achieved by analyzing SPEX CERTIPREP standard samples with no significant differences. 85-120% recovery percentages for digested biota were obtained. The precision was less than 10% of relative standard deviation in all the cases. The method is reliable for mercury determination in water, red-bellied and Lemna minor tissue.

Detection of stable isotopes with a (n, α) nuclear reaction: application to the measurement of unidirectional fluxes of borate in a plant

International Nuclear Information System (INIS)

Duval, Y.; Thellier, M.; Heurteaux, C.; Wissocq, J.C.

1980-01-01

The unidirectional influx of borate has been studied in Lemna minor plants with the aid of purified boron isotopes, 10 B and 11 B. Isotope 10 B was detected specifically by nuclear reaction 10 B(n, α) 7 Li in the presence of ''homogeneous'' detectors. Despite technical difficulties in performing the 10 B-estimations in the plant samples themselves, the results obtained here were consistent with those of efflux experiments, published previously, where the 10 B-measurements were performed in the external solution. Kinetic parameters of borate transports in Lemna minor have been calculated. (author)

Interim Regional Supplement to the Corps of Engineers Wetland Delineation Manual: Midwest Region

Science.gov (United States)

2008-09-01

Ceratophyllum demersum), bladderwort (Utricularia macrorhiza), white water crowfoot (Ranunculus longirostris), and duckweeds ( Lemna , Spirodela, and...divide the landscape into areas called map units. Map units usually contain more than one soil type or component. They often contain several minor ...bladderworts (Utricularia spp.), and duckweeds ( Lemna spp.) (Figure 36). Figure 36. Dried remains of water-lilies in a semipermanently ponded

Evaluation of the effects of diuron and its derivatives on Lemna gibba using a fluorescence toxicity index.

Science.gov (United States)

Dewez, David; Marchand, Mathieu; Eullaffroy, Philippe; Popovic, Radovan

2002-10-01

The herbicide diuron (DCMU) [3-(3,4-dichlorophenyl)-1,1-dimethylurea] is largely used in agricultural practices which contribute to water pollution in large areas. Its degradation induced by light or microbial activity is known to be a slow process, and may result in the accumulation of DCMU derivatives in the environment. In this report we used the yield of PSII variable fluorescence of Lemna gibba affected by the DCMU derivatives DCPMU [1-(3,4-dichlorophenyl)-3-methylurea], DCPU [1-(3,4-dichlorophenyl)urea], and DCA [3,4-dichloroaniline] to calculate the fluorescence toxicity index. We found the fluorescence toxicity index to be a useful parameter to evaluate the inhibitory effect on PSII electron transport in L. gibba exposed to DCMU and its derivatives. The variations observed for the inhibitory effect between DCMU and its derivatives seem to be caused by the modification of the dimethylurea group within the DCMU molecule. The fluorescence toxicity index demonstrated a strong quantitative dependency between the inhibitory effect of PSII electron transport and pollutant concentrations. We propose the fluorescence toxicity index to be a useful tool for future bioassays in evaluating the quality of water polluted with herbicides that induce an inhibition to PSII photochemistry. Copyright 2002 Wiley Periodicals, Inc.

不同浓度养殖废水对青萍生长能力的影响%Influence of livestock wastewater concentration on growth of common duckweed (Lemna minor)

Institute of Scientific and Technical Information of China (English)

顾新娇; 杨闯; 王文国; 汤晓玉; 胡启春

2015-01-01

为了探讨废水浓度对青萍(Lemna minor)净化能力、生物质和能量积累能力的影响,以猪场养殖废水为供试废水,分析了在不同废水浓度下青萍对废水中总氮(TN)、氨氮和总磷(TP)的净化能力,青萍的生长情况,以及青萍中碳(C)、氮(N)、磷(P)元素含量和热值的变化情况.研究表明,青萍在1％浓度的废水中表现出最高的污染物净化能力.虽然青萍的C、N、P含量和热值均随废水浓度的增加而增加,但是由于相对增长率以1％的废水中生长的青萍最高,青萍的最高生产力、C和能量的固定能力均出现在1％废水浓度培养的青萍中,其次是5％废水浓度培养的青萍.多项式回归分析表明,可以使青萍获得最大C和能量固定能力的废水浓度为3.4％,对应的氨氮浓度为26 mg./L,TP浓度为3.4 mg/L.研究结果为进一步优化高生物质生产、高污染物去除率的养殖废水-浮萍培养体系提供了一定的基础.

Effect of additional minor elements on accumulation behavior of point defects under electron irradiation in austenitic stainless steels

International Nuclear Information System (INIS)

Sekio, Yoshihiro; Yamashita, Shinichiro; Takahashi, Heishichiro; Sakaguchi, Norihito

2014-01-01

Addition of minor elements to a base alloy is often applied with the aim of mitigating void swelling by decreasing the vacancy diffusivity and flux which influence vacancy accumulation behavior. However, the comparative evaluations of parameters, such as the diffusivity and flux, between a base alloy and modified alloys with specific additives have not been studied in detail. In this study, type 316 austenitic stainless steel as a base alloy and type 316 austenitic stainless steels modified with vanadium (V) or zirconium (Zr) additions were used to perform evaluations from the changes of widths of the void denuded zone (VDZ) formed near a random grain boundary during electron irradiation because these widths depend on vacancy diffusivity and flux. The formations of VDZs were observed in in-situ observations during electron irradiation at 723 K and the formed VDZ widths were measured from the transmission electron microscopic images after electron irradiation. As a result, the VDZs were formed in both steels without and with V, and respective widths were ∼119 and ∼100 nm. On the other hand, the VDZ formation was not observed clearly in the steel with Zr. From the measured VDZ widths in the steels without and with V addition, the estimated ratio of the vacancy diffusivity in the steel with V to that in the steel without V was about 0.50 and the estimated ratio of the vacancy flux in the steel with V to that in the steel without V was about 0.71. This result suggests that the effect of additional minor elements on vacancy accumulation behaviors under electron irradiation could be estimated from evaluations of the VDZ width changes among steels with and without minor elements. Especially, because void swelling is closely related with the vacancy diffusion process, the VDZ width changes would also be reflected on void swelling behavior. (author)

Regional Supplement to the Corps of Engineers Wetland Delineation Manual: Midwest Region (Version 2.0)

Science.gov (United States)

2010-08-01

bladderwort (Utricularia macrorhiza), white water crowfoot (Ranunculus longirostris), and duckweeds ( Lemna , Spirodela, and Wolffia). As mentioned...units. Map units usually contain more than one soil type or component. They often contain several minor components or inclusions of soils with...bladderworts (Utricularia spp.), and duckweeds ( Lemna spp.) (Figure 37). ERDC/EL TR-10-16 87 Figure 37. Dried remains of water-lilies in a

Detection of stable isotopes with a (n,. cap alpha. ) nuclear reaction: application to the measurement of unidirectional fluxes of borate in a plant

Energy Technology Data Exchange (ETDEWEB)

Duval, Y; Thellier, M; Heurteaux, C; Wissocq, J C [Centre National de la Recherche Scientifique, Mont-Saint-Aignan (France). Lab. ' ' Echanges cellulaires' '

1980-01-01

The unidirectional influx of borate has been studied in Lemna minor plants with the aid of purified boron isotopes, /sup 10/B and /sup 11/B. Isotope /sup 10/B was detected specifically by nuclear reaction /sup 10/B(n, ..cap alpha..)/sup 7/Li in the presence of ''homogeneous'' detectors. Despite technical difficulties in performing the /sup 10/B-estimations in the plant samples themselves, the results obtained here were consistent with those of efflux experiments, published previously, where the /sup 10/B-measurements were performed in the external solution. Kinetic parameters of borate transports in Lemna minor have been calculated.

Process for sewage biological treatment from uranium

International Nuclear Information System (INIS)

Popa, K.; Cecal, A.; Craciun, I.

2004-01-01

The invention relates to the sewage treatment, in particular to the sewage biological treatmen from radioactive waste, namely from uranium. The process dor sewage biological treatment from uranium includes cultivation in the sewage of the aquatic plants Lemna minor and Spirulina platensis. The plants cultivation is carried out in two stages. In the first stage for cultivation is used Lemna minor in the second stage - Spirulina platensis . After finishing the plant cultivation it is carried out separation of their biomass. The result of the invention consists in increasing the uranyl ions by the biomass of plants cultivated in the sewage

Process for sewage biological treatment from uranium

International Nuclear Information System (INIS)

Popa, Karin; Cecal, Alexandru; Craciun, Iftimie Ionel; Rudic, Valeriu; Gulea, Aurelian; Cepoi, Liliana

2004-01-01

The invention relates to the sewage treatment, in particular to the sewage biological treatment from radioactive waste, namely from uranium. The process for sewage biological treatment from uranium includes cultivation in the sewage of the aquatic plants Lemna minor and Spirulina platensis. The plant cultivation is carried out in two stages. In the first stage for cultivation is used Lemna minor and in the second stage - Spirulina platensis. After finishing the plant cultivation it is carried out separation of their biomass. The result of the invention consists in increasing the uranyl ions accumulation by the biomass of plants cultivated in the sewage.

The Study on Effect of Hg,Cd and Their Combined Pollution in Leaves of Lemna minor L.%Hg、Cd及其复合污染对浮萍叶片的毒害研究

Institute of Scientific and Technical Information of China (English)

徐楠; 施国新; 杜开和; 张小兰; 曾晓敏; 周红卫

2002-01-01

研究了不同浓度Hg、Cd及其复合污染对浮萍(Lemna minor L.)叶片生理生化以及超微结构的毒害影响.经观察分析,培养4d后各处理组均呈现出不同程度的受害症状.随处理浓度的递增,叶绿素含量以及可溶性蛋白含量明显下降;抗氧化酶系统活性及脯氨酸含量均表现出一显著抗性峰,而后下降.通过电镜观察发现,叶绿体膨胀,外膜破裂,基粒片层垛叠混乱;线粒体脊突膨胀,呈现凌乱状态甚至空泡状残体;细胞核变形,核膜内陷,染色质凝集,呈无序状态甚至解体.结果表明:Cd对浮萍叶细胞的毒性比Hg大,Hg、Cd复合污染呈现明显的协同作用,加强了对叶细胞的伤害.Hg对于浮萍叶片的致死浓度在5～7mg/L之间;Cd的致死浓度在2.5～5mg/L之间;Hg+Cd的致死浓度在1mg/L Hg+1mg/L Cd～2.5mg/L Hg+2.5mg/LCd 之间.

Ion heating in minority ICRH experiments on JET

International Nuclear Information System (INIS)

Start, D.F.H.; Bhatnagar, V.; Bures, M.

1991-06-01

Bulk ion heating by high power H-minority ICRH has been demonstrated in JET during both pellet enhanced performance H-mode experiments (PEP + H - mode) and in density limit studies. In the PEP + H - mode plasmas the electron and ion temperatures both reached 10 keV at an electron density of 7 x 10 19 /m 3 . According to Fokker-Planck calculations the power from the minority was transfered almost equally to the electrons and majority ions as a result of both the high electron density, n e , and the high minority density, n h , (n h /n e ≅ 0.15). For the first time with ICRH on JET a central ion temperature greater than the central electron temperature was achieved. In the density limit experiments which involved strong gas puffing into limiter discharges, there was strong evidence of a transfer from electron heating to ion heating as the electron density was ramped up to 8 x 10 19 /m 3 . (Author)

Different toxicity mechanisms between bare and polymer-coated copper oxide nanoparticles in Lemna gibba

International Nuclear Information System (INIS)

Perreault, François; Popovic, Radovan; Dewez, David

2014-01-01

In this report, we investigated how the presence of a polymer shell (poly(styrene-co-butyl acrylate) alters the toxicity of CuO NPs in Lemna gibba. Based on total Cu concentration, core–shell CuO NPs were 10 times more toxic than CuO NPs, inducing a 50% decrease of growth rate at 0.4 g l −1 after 48-h of exposure while a concentration of 4.5 g l −1 was required for CuO NPs for a similar effect. Toxicity of CuO NPs was mainly due to NPs solubilization in the media. Based on the accumulated copper content in the plants, core–shell CuO NPs induced 4 times more reactive oxygen species compared to CuO NPs and copper sulfate, indicating that the presence of the polymer shell changed the toxic effect induced in L. gibba. This effect could not be attributed to the polymer alone and reveals that surface modification may change the nature of NPs toxicity. -- Highlights: • Bare and polymer-coated CuO nanoparticles were toxic to Lemna gibba. • Toxicity of bare CuO was mainly due to solubilized soluble copper. • Coated CuO accumulated inside the plants four times more. • Formation of reactive oxygen species was increased by polymer coating. • Coating of nanomaterials modifies mechanisms of action at cellular level. -- Polymer coating increases oxidative stress effect by core–shell CuO nanoparticles

A simple method for analysing the effects of algae on the growth of Lemna and preventing algal growth in duckweed bioassays

NARCIS (Netherlands)

Szabo, S.; Roijackers, R.M.M.; Scheffer, M.

2003-01-01

A simple novel method for indoor culture experiments with small floating water plants, such as Lemnaceae, is described. Experiments demonstrate that the method allows for longer lasting culture experiments with Lemna, avoiding algal growth and self-shading of fronds by overcrowding. This is achieved

Biological Screening of Eichornia crassipes against Different Pathogenic Microbes: An In Vitro Study

Directory of Open Access Journals (Sweden)

Rubina Rehman

2016-09-01

Full Text Available The present research is a biological screening of Eichornia crassipes (Pontederiaceae. Dichloromethane and methanol extracts of the whole plant were investigated for their antibacterial, antifungal, phytotoxic, and cytotoxic activities. The antibacterial activity was evaluated using agar well-diffusion method against Bacillus subtilis, Staphylococcus aureus, Escherichia coli, Shigella flexneri, Pseudomonas aeruginosa, and Salmonella typhi. The antifungal activity was evaluated using the agar tube–dilution method against Candida albicans, Candida glabrata, Aspergillus flavus, Microsporum canis, and Fusarium solani. The phytotoxicity activity was determined using Lemna bioassay against Lemna minor. Brine shrimp–cytotoxicity assay was determined against brine-shrimp larvae. Dichloromethane extract exhibited significant phytotoxicity (100% growth regulation at 1,000 µg/ml concentration against Lemna minor whereas methanolic extracts showed moderate (75% growth regulation phytotoxicity at the same concentration. Methanolic extract showed cytotoxicity at the highest level of dose whereas dichloromethane extract showed no activity having Etoposide as standard drug. Both of the extracts have nonsignificant antifungal and antibacterial activity.

State laws prohibiting sales to minors and indoor use of electronic nicotine delivery systems--United States, November 2014.

Science.gov (United States)

Marynak, Kristy; Holmes, Carissa Baker; King, Brian A; Promoff, Gabbi; Bunnell, Rebecca; McAfee, Timothy

2014-12-12

Electronic nicotine delivery systems (ENDS), including electronic cigarettes (e-cigarettes) and other devices such as electronic hookahs, electronic cigars, and vape pens, are battery-powered devices capable of delivering aerosolized nicotine and additives to the user. Experimentation with and current use of e-cigarettes has risen sharply among youths and adults in the United States. Youth access to and use of ENDS is of particular concern given the potential adverse effects of nicotine on adolescent brain development. Additionally, ENDS use in public indoor areas might passively expose bystanders (e.g., children, pregnant women, and other nontobacco users) to nicotine and other potentially harmful constituents. ENDS use could have the potential to renormalize tobacco use and complicate enforcement of smoke-free policies. State governments can regulate the sales of ENDS and their use in indoor areas where nonusers might be involuntarily exposed to secondhand aerosol. To learn the current status of state laws regulating the sales and use of ENDS, CDC assessed state laws that prohibit ENDS sales to minors and laws that include ENDS use in conventional smoking prohibitions in indoor areas of private worksites, restaurants, and bars. Findings indicate that as of November 30, 2014, 40 states prohibited ENDS sales to minors, but only three states prohibited ENDS use in private worksites, restaurants, and bars. Of the 40 states that prohibited ENDS sales to minors, 21 did not prohibit ENDS use or conventional smoking in private worksites, restaurants, and bars. Three states had no statewide laws prohibiting ENDS sales to minors and no statewide laws prohibiting ENDS use or conventional smoking in private worksites, restaurants, and bars. According to the Surgeon General, ENDS have the potential for public health harm or public health benefit. The possibility of public health benefit from ENDS could arise only if 1) current smokers use these devices to switch completely

Toxic Effects of Nickel Oxide Bulk and Nanoparticles on the Aquatic Plant Lemna gibba L.

Directory of Open Access Journals (Sweden)

Abdallah Oukarroum

2015-01-01

Full Text Available The aquatic plant Lemna gibba L. was used to investigate and compare the toxicity induced by 30 nm nickel oxide nanoparticles (NiO-NPs and nickel(II oxide as bulk (NiO-Bulk. Plants were exposed during 24 h to 0–1000 mg/L of NiO-NPs or NiO-Bulk. Analysis of physicochemical characteristics of nanoparticles in solution indicated agglomerations of NiO-NPs in culture medium and a wide size distribution was observed. Both NiO-NPs and NiO-Bulk caused a strong increase in reactive oxygen species (ROS formation, especially at high concentration (1000 mg/L. These results showed a strong evidence of a cellular oxidative stress induction caused by the exposure to NiO. Under this condition, NiO-NPs and NiO-Bulk induced a strong inhibitory effect on the PSII quantum yield, indicating an alteration of the photosynthetic electron transport performance. Under the experimental conditions used, it is clear that the observed toxicity impact was mainly due to NiO particles effect. Therefore, results of this study permitted determining the use of ROS production as an early biomarker of NiO exposure on the aquatic plant model L. gibba used in toxicity testing.

Proposal for electron beam induced remote sensing x-ray fluorescence investigation of minor bodies in the solar system

International Nuclear Information System (INIS)

Hrehuss, G.; Gombosi, T.I.; Naday, I.; Pogany, L.; Szegoe, K.

1983-11-01

The composition of the surface material of minor bodies in the solar system can be measured using a semiconductor soft x-ray spectrometer mounted on the space probe. The characteristic x-rays are excited by a 20 kV low current electron beam of a space-born electron gun. After the description of the main features of the technique, estimations on its sensitivity, supported by a model experiment, are given. The minimum fly-by distance to apply this method can be estimated as a few kilometers. (author)

Circadian Rhythmicity in the Activities of Phenylalanine Ammonia-Lyase from Lemna perpusilla and Spirodela polyrhiza 1

Science.gov (United States)

Gordon, William R.; Koukkari, Willard L.

1978-01-01

The oscillations in phenylalanine ammonia-lyase activity from Spirodela polyrhiza and phenylalanine ammonia-lyase and tyrosine ammonia-lyase activities from Lemna perpusilla displayed a circadian rhythm under continuous light. Rhythmicity in enzymic activity could not be detected in continuous darkness since under this condition phenylalanine ammonia-lyase activity remains at a fairly constantly low level. Results from our studies of the oscillatory pattern of the respective activities of phenylalanine and tyrosine ammonia-lyase support their “inseparability.” PMID:16660569

青萍生长特征及其对受污染河水的修复效果%Growth characteristics and purification efficiencies of Lemna minor to polluted river water

Institute of Scientific and Technical Information of China (English)

鲁言言; 黄磊; 刘明; 杜刚; 高旭

2013-01-01

以浮萍优势品种青萍(Lemna minor)为研究对象,开展受污染河水修复.分析了青萍在不同营养盐浓度条件下的生长特征,探讨了青萍对受污染河水的修复效果.在表面积为0.0095 m2的限制空间条件下,青萍在1、2和5 mg总氮(TN)/L营养液中的生长特征都能较好地服从Logistic生长模型,受制约的临界鲜重(FW)分别为1.20、1.36和1.36 g；青萍对受污染河水中氮磷污染物具有较好的去除效果,氨氮(NH+4-N)的平均去除率、平均去除量和平均去除速率分别为56.87％、1.22 mg/d和0.0466 mg/(g FW·h),正磷酸盐(PO3-4-P)的平均去除率、平均去除量和平均去除速率分别为66.95％、0.25 mg/d和0.0088 mg/(g FW·h).根据相关性分析,进水NH+4-N和PO3-4-P浓度与其对应去除量之间极显著相关；青萍FW与NH+4-N去除速率之间显著负相关,但与P03-4-P去除速率之间不存在显著相关性；NH+4-N进水浓度与去除速率相关性不显著,但P03-4-P进水浓度与去除速率显著正相关.

75 FR 11010 - Endangered and Threatened Wildlife and Plants; Designation of Critical Habitat for Oregon Chub...

Science.gov (United States)

2010-03-10

... remain at low levels. Comments from States We received several recommendations for minor corrections to... moss), Lemna spp. (duckweed), Myriophyllum spp. (parrot feather), Nuphar spp. (pondlily), and...

Environmental Assessment: Land Acquisition at Whiteman Air Force Base, Missouri

Science.gov (United States)

2011-06-01

Canadian clearweed (Pilea pumila), common duckweed ( Lemna minor ), common rush (Juncus effusus), cottonwood (Populus deltoides), crabgrass...resources, hazardous materials and hazardous waste, and safety. Implementation of the Proposed Action would result in minor , short-term adverse impacts...consumption of petroleum products during fence construction. As a result of implementing the Proposed Action, minor long-term adverse impacts to land use

Amino acid metabolism of Lemna minor L

International Nuclear Information System (INIS)

Rhodes, D.; Rich, P.J.; Brunk, D.G.

1989-01-01

A serious limitation to the use of N(O,S)-heptafluorobutyryl isobutyl amino acid derivatives in the analysis of 15 N-labeling kinetics of amino acids in plant tissues, is that the amides glutamine and asparagine undergo acid hydrolysis to glutamate and aspartate, respectively, during derivatization. This led us to consider an alternative procedure for derivatization of glutamine and asparagine with N-methyl-N-(tert-butyldimethylsilyl)-trifluoroacetamide in pyridine. Gas chromatography-mass spectrometry yielded fragment ions (M-57) of mass 417 and 431 for the [ 14 N]asparagine and [ 14 N]glutamine derivatives, respectively, suitable for monitoring unlabeled, single- 15 N- and double- 15 N-labeled amide species from the ion clusters at mass to charge ratio (m/z) 415 to 423 for asparagine, and m/z 429 to 437 for glutamine. From separate analyses of the specific isotope abundance of the amino-N groups of asparagine and glutamine as their N-heptafluorobutyryl isobutyl derivatives, the specific amide-[ 15 N] abundance of these amino acids was determined

Bioleaching of UO22+ ions from a Romanian poor uranium ore

International Nuclear Information System (INIS)

Cecal, Al.; Popa, K.; Moraru, R.T.; Patachia, S.

2002-01-01

An experimental study on the bioleaching of a poor uranium ore by means of hydrophytic plants Lemna minor and Riccia fluitans, under various operating conditions is discussed. The maximum degree of bioleaching (42%) of the reduced uranium species to U(VI) has been attained for the ore-Lemna minor-alkaline carbonate solution system. The UO 2 2+ ions amount accumulated in the plants is negligible as compared to the dissolved quantity, owing to the ionic competition between uranyl ions and the cations necessary to the mineral nutrition. The X-ray diffraction patterns prove that the uranium species in pyrochlore mineral are completely oxidized to U(VI), while thucolite is only partially turned into UO 2 2+ ions, in the presence of living plants. (author)

Decontamination of radioactive liquid wastes by hydrophytic vegetal organisms

International Nuclear Information System (INIS)

Cecal, Al; Popa, K.; Potoroaca, V.; Melniciuc-Puica, N.

2001-01-01

Bioaccumulation of some radioactive ions from contaminated waste solutions, on hydrophytic vegetal organisms is discussed. In order to follow the distribution of radioactive ions 137 Cs + , 60 Co 2+ and 51 Cr 3+ in various cell components extracted from Spirulina platensis, Porphiridium cruentum, Scenedesmus quadricauda, Lemna minor, Elodea canadensis, Pistia stratiotes and Riccia fluitans, the plants were cultivated in radioactive solutions. The resulting complexes were extracted with acetone or acetic acid and separated chromatographically. The results show an intense activity of the polysaccharide and lipoid fractions in the bioaccumulation process. The bioaccumulation varies in the series: Spirulina > Scenedesmus > Porphiridium > Riccia > Pistia > Lemna ≥ Elodea for 137 Cs + and 60 Co 2+ ; Spirulina > Porphiridium > Scenedesmus > Riccia > Pistia > Lemna > Elodea for 51 Cr 3+ . (author)

Environmental Assessment: Permanent Western United States C-17 Landing Zone

Science.gov (United States)

2008-09-01

Salix sp., Populus sp., Lemna minor , Cyperus sp. Delta Green Ground Beetle The Delta Green Ground Beetle, Elaphrus viridis Horn, 1878 is a...and the SCLA. Cumulative impacts can result from individually minor but collectively significant actions taking place over a period of time. None of...environmental effects on adjacent populations. Therefore, no disproportionately high and adverse effects will occur to minority and low-income

Biodiesel production from Jatropha curcas L. oil using Lemna perpusilla Torrey ash as heterogeneous catalyst

International Nuclear Information System (INIS)

Chouhan, Ashish Pratap Singh; Sarma, Anil Kumar

2013-01-01

Refined Jatropha curcas L. oil (JCO) and methanol were used as the reactants for the transesterification reactions in a Radleys reactor in the presence of a heterogeneous ash catalyst derived from the waste aquatic plant Lemna perpusilla Torrey. Physical characterization of the catalyst showed partly crystalline behaviour and a moderate surface area 9.622 m 2 g −1 . The L. perpusilla Torrey ashes obtained from traditional combustion method were further calcined at 550 ± 5 °C before use. In addition to other non-metal and metallic constitutes the ash contains 11.3% potassium which attributed to its catalytic behaviour. The cumulative mass fraction of 89.43% of the oil was converted to biodiesel at 65 ± 5 °C in 5 h at 1:9 M ratio of oil to alcohol with 5% of the ash as catalyst. The biodiesel (FAME) so obtained were characterized using appropriate ASTM methods and found within the defined standard limits. The catalyst could be reused upto 3-times but there is a reduction of efficacy by about 25% for 3rd consecutive batch reaction. The activation energy was calculated for FAME and found to be 29.49 kJ mol −1 . -- Highlights: ► Lemna perpusilla Torrey ash is a potential heterogeneous catalyst. ► The catalyst has moderately good surface area and pores. ► The ash contain 11.3% potassium which is attributed to its catalytic behaviour. ► 89.43% of the refined Jatropha curcas oil could be converted to FAME in a Radleys reactor. ► The activation energy for FAME was calculated and found to be 29.49 kJ mol −1

Pós-tratamento de efluente de reator anaeróbio em lagoa com lemna

OpenAIRE

Lubarino, Elizângela Alves

2013-01-01

A ausência de tratamento e a disposição inadequada de efluentes domésticos contribuem para a deterioração de corpos receptores. Porém, dentre as alternativas propostas para o pós-tratamento de águas residuárias estão as lagoas de lemnas. Essas lagoas são capazes de captar nutrientes do esgoto com eficiência, bem como, reduzir uma grande quantidade de sólidos em suspensão. Também atuam na inibição de algas, e geram biomassa rica em proteínas que tem utilidades como ração animal e adubo. Esta p...

Avaliação de lagoas de lemnas para o polimento de esgoto doméstico

OpenAIRE

Tonon, Gustavo

2016-01-01

Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro Tecnológico, Programa de Pós-Graduação em Engenharia Ambiental, Florianópolis, 2016. As lagoas de lemnas têm sido utilizadas com sucesso para o polimento de efluentes nos últimos anos, destacando a grande capacidade de remoção de nutrientes, e a produção de biomassa passível de valorização. O presente estudo objetivou avaliar esta tecnologia no tratamento de esgoto doméstico, investigar a produção de gás metano em test...

Spectral Reflectance of Duckweed (Lemna Gibba L.) Fronds Exposed to Ethylene Glycol

Science.gov (United States)

Dong, Weijin; Carter, Gregory A.; Barber, John T.

2001-01-01

When duckweed (Lemna Gibba L.) fronds are exposed to ethylene glycol (EG) anatomy is altered, allowing an increase in water uptake that causes a darkening of frond appearance. Spectroradiometry was used to quantify changes in frond reflectance that occurred throughout the 400-850 nm spectrum under various EG concentrations and exposure times. The threshold concentration of EG at which a reflectance change could be detected was between 35 and 40 mM, approximately the same as by visual observation. EG-induced changes in frond reflectance were maximum at concentrations of 50 mM or greater. Reflectance changes were detectable within 24h of exposure to 100 mM EG,2-3 days prior to changes in frond appearance. The spectroradiometry of duckweed may serve as a rapid and sensitive technique for detection of ecosystem exposure to EG and perhaps other stress agents.

Antimicrobial, Cytotoxic and Phytotoxic Potency of Ethyl Acetate ...

African Journals Online (AJOL)

The antifungal activity was determined by inhibitory effect on the growth of. Alternaria ... Results: The extract showed phytotoxic activity (at 95% level of significance) against Lemna minor ..... screening of various organic extracts of caesalpinia.

Impacts of UV radiation and photomodification on the toxicity of PAHs to the higher plant Lemna gibba (duckweed)

International Nuclear Information System (INIS)

Huang, X.D.; Dixon, D.G.; Greenberg, B.M.

1993-01-01

The toxicity of polycyclic aromatic hydrocarbons (PAHs) can be enhanced by both biotic and abiotic processes. This is exemplified by light, which, by virtue of the extensive π-orbital systems of PAHs, can be a major factor in PAH toxicity. Light activation of PAHs is known to occur via photosensitization reactions (generation of singlet oxygen and superoxide) and potentially by photomodification of the chemicals (photooxidation and/or photolysis) to more toxic species. To examine the modes of PAH action in the light and determine if the photomodified compounds are hazardous, we investigated the photoinduced toxicity of anthracene, phenanthrene and benzo[a]pyrene to the aquatic higher plant Lemna gibba (a duckweed). Toxicity end points were inhibition of growth and extent of chlorosis. Light did indeed activate the phytotoxicity of PAHs, with UV radiation more effective than visible light. Dose-response curves based on chemical concentration and light intensity revealed the order of phytotoxic strength to be anthracene > phenanthrene > benzo[a]pyrene. To explore whether photomodified PAHs were contributing to toxicity, the chemicals were irradiated before toxicity testing. The rates of photomodification of the three PAHs were rapid (half-lives in hours), and the relative velocities were coincident with the order of toxic strength. Furthermore, the photomodified PAHs were more hazardous to Lemna than the intact compounds. Because interpretations of the potential impacts of PAHs in the environment are based mostly on measurements of the structurally intact chemicals, the severity of PAH hazards is possibly underestimated

Membrane potential and proton cotransport of alanine and phosphate as affected by permeant weak acids in Lemna gibba

International Nuclear Information System (INIS)

Basso, B.; Ullrich-Eberius, C.I.

1987-01-01

The treatment of Lemna gibba plants with the weak acids (trimethylacetic acid and butyric acid), used as tools to decrease intracellular pH, induced a hyperpolarization of membrane potential, dependent on the concentration of the undissociated permeant form of the weak acid and on the value of the resting potential. Measurements were carried out both with high potential and low potential plants and the maximum values of acid induced hyperpolarization were about 35 and 71 millivolts, respectively. Weak acids influenced also the transient light-dark membrane potential changes, typical for photosynthesizing material, suggesting a dependence of these changes on an acidification of cytoplasm. In the presence of the weak acids, the membrane depolarization induced by the cotransport of alanine and phosphate with protons was reduced; the maximum reduction (about 90%) was obtained with alanine during 2 millimolar trimethylacetic acid perfusion at pH 5. A strong inhibition of the uptake rates (up to 48% for [ 14 C]alanine and 68% for 32 P-phosphate) was obtained in the presence of the weak acids, both by decreasing the pH of the medium and by increasing the concentration of the acid. In these experimental conditions, the ATP level and O 2 uptake rates did not change significantly. These results constitute good evidence that H + /solute cotransport in Lemna, already known to be dependent on the electrochemical potential difference for protons, is also strongly regulated by the cytoplasmic pH value

Evaluation of Cumulative Ecosystem Response to Restoration Projects in the Lower Columbia River and Estuary, 2010

Science.gov (United States)

2012-05-01

LEOR Leersia oryzoides Rice cutgrass OBL Grass yes LEMI Lemna minor Duckweed OBL Herb yes LEVU Leucanthemum vulgare Oxeye daisy UPL Herb no yes...discharge today of 7,730 m3/s (Stanford et al. 2005). Historical flows, prior to river regulation by some 30 major dams and numerous minor dams...dominated by reed canarygrass. The changes between years were relatively minor , with one plot changing from 50% Lyngbye’s sedge and 50% reed

A no iso ovel po lation olymera of a ne ase ch ew rbc hain rea cS ...

African Journals Online (AJOL)

sunny

Hubei Norma ed 14 December, ymerase cha mosome wa ndle PCR in i. 3' downstrea mna minor ge isolated from ch was confi ion-mediated s in the isola. Lemna minor es have be omic fragme without go nomic librar chain react y been appl al PCR metho. Inverse PC and Chen, 200 gation-mediat. Villalobos et a. 2003; Dai ...

Assessment of acrylamide toxicity using a battery of standardised bioassays.

Science.gov (United States)

Zovko, Mira; Vidaković-Cifrek, Željka; Cvetković, Želimira; Bošnir, Jasna; Šikić, Sandra

2015-12-01

Acrylamide is a monomer widely used as an intermediate in the production of organic chemicals, e.g. polyacrylamides (PAMs). Since PAMs are low cost chemicals with applications in various industries and waste- and drinking water treatment, a certain amount of non-polymerised acrylamide is expected to end up in waterways. PAMs are non-toxic but acrylamide induces neurotoxic effects in humans and genotoxic, reproductive, and carcinogenic effects in laboratory animals. In order to evaluate the effect of acrylamide on freshwater organisms, bioassays were conducted on four species: algae Desmodesmus subspicatus and Pseudokirchneriella subcapitata, duckweed Lemna minor and water flea Daphnia magna according to ISO (International Organization for Standardisation) standardised methods. This approach ensures the evaluation of acrylamide toxicity on organisms with different levels of organisation and the comparability of results, and it examines the value of using a battery of low-cost standardised bioassays in the monitoring of pollution and contamination of aquatic ecosystems. These results showed that EC50 values were lower for Desmodesmus subspicatus and Pseudokirchneriella subcapitata than for Daphnia magna and Lemna minor, which suggests an increased sensitivity of algae to acrylamide. According to the toxic unit approach, the values estimated by the Lemna minor and Daphnia magna bioassays, classify acrylamide as slightly toxic (TU=0-1; Class 1). The results obtained from algal bioassays (Desmodesmus subspicatus and Pseudokirchneriella subcapitata) revealed the toxic effect of acrylamide (TU=1-10; Class 2) on these organisms.

Industrial wastewater treatment using higher aquatic vegetation in the former mining company of the Far Eastern Federal district

Science.gov (United States)

Krupskaya, L. T.; Zvereva, V. P.; Gula, K. E.; Gul', L. P.; Golubev, D. A.; Filatova, M. Yu.

2017-09-01

The article describes the results of studying the problems of industrial wastewater treatment using higher aquatic vegetation (hydrophytes) in the former mining enterprise of the Far Eastern Federal District (FEFD). They are aimed at reducing the negative environment impact of toxic tin ore wastes. The material of research were drainage, mine and slime waters as well as Lemna minor and Common reed grass (Phragmites communis). In the work conventional modern physico-chemical, chemical, biological and mathematical-statistical methods were used, as well as in the process of research the methods of atomic absorption spectrophotometry for AAS and mass spectrometry with inductively coupled plasma on ISP-MS ELASN DRS II PerkinElmer was applied. The data obtained in the course of the experiment (2015-2016), indicate that a degree of wastewater treatment, using Lemna minor, is high. Virtually, all compounds of toxic chemical elements contained in industrial wastewater (zinc, cobalt, nickel, cadmium, iron, manganese, lead, etc.) were fully absorbed by a hydrophyte. Pollutant extraction was almost 95%. The obtained results of the study in laboratory conditions proved the possibility of effective use of the Lemna minor for the purification of drainage and mine waters. A key contribution of this paper is the relationship between possible toxic metals contained in industrial wastewater and a higher degree of absorption by their higher aquatic vegetation. These hydrophytes absorb these possible toxic metals in an aqueous medium and are contaminated with these heavy metals.

青萍在Pb、Cu污染水体植物修复中的应用研究%Study of duckweed（Lemna perpusilla Torr.） for use in phytoremediation of lead-and copper-contaminated water bodies

Institute of Scientific and Technical Information of China (English)

唐艳葵; 韦星任; 姚秋艳; 蓝梓铭; 李婷

2011-01-01

Duckweed（Lemna perpusilla Torr.） was used as experimental materials and several physiological responses of Lemna perpusilla Torr.,such as biomass growth,pigment contents,adsorption characteristics of heavy metals,nitrogen and phosphorus,to elevated concentrations of Pb（Ⅱ）（up to 40 mg/L） and Cu（Ⅱ）（up to 4 mg/L） were investigated.The results showed that high metal concentration might inhibit the growth of Lemna perpusilla Torr.Copper was found to be more toxic to plants than lead.It was demonstrated that exposure to high concentrations of lead and copper results in the high bioaccumulation of metals in Lemna perpusilla Torr.（26.09 mg/g of Pb in the plant grown in water with 40 mg/L Pb（Ⅱ） and 2.49 mg/g of Cu in the plant grown in water with 4 mg/L Cu（Ⅱ））.At these levels the plant growth was significantly inhibited and the plant pigment content significantly decreased.Also,a significant release of P and N was observed at these high levels of metal stress.The results of this study confirm that Lemna perpusilla Torr.is a suitable candidate for the phytoremediation in low-level lead-contaminated water bodies.%以青萍种浮萍（Lemna perpusilla Torr.）为实验材料,以Pb（Ⅱ）、Cu（Ⅱ）为染毒因子,设定金属离子浓度梯度（Pb（Ⅱ）：0～40 mg/L,Cu（Ⅱ）：0～4 mg/L）,考察了在不同金属离子浓度下青萍生长状况、叶片色素含量以及金属离子浓度对青萍N、P和金属离子吸收能力的影响。结果表明：金属离子浓度的越高,青萍生长受抑制越严重;Cu（Ⅱ）对青萍的毒害大于Pb（Ⅱ）;在Pb（Ⅱ）浓度为40 mg/L,Cu（Ⅱ）浓度为4 mg/L时,青萍对Pb（Ⅱ）和Cu（Ⅱ）的平均单位鲜重富集量分别为26.09 mg/g和2.49 mg/g,但同时,青萍的生长受到严重抑制,叶绿素含量急剧下降,且N、P从细胞中溶出。研究表明,青萍比较适宜修复被低浓度Pb（Ⅱ）污染的水体。

The occurrence of hormesis in plants and algae

DEFF Research Database (Denmark)

Cedergreen, Nina; Streibig, Jens Carl; Kudsk, Per

2007-01-01

This paper evaluated the frequency, magnitude and dose/concentration range of hormesis in four species: The aquatic plant Lemna minor, the micro-alga Pseudokirchneriella subcapitata and the two terrestrial plants Tripleurospermum inodorum and Stellaria media exposed to nine herbicides and one...

Bioaccumulation and toxicity assessment of irrigation water contaminated with boron (B) using duckweed (Lemna gibba L.) in a batch reactor system.

Science.gov (United States)

Türker, Onur Can; Yakar, Anıl; Gür, Nurcan

2017-02-15

The present study assesses ability of Lemna gibba L. using a batch reactor approach to bioaccumulation boron (B) from irrigation waters which were collected from a stream in largest borax reserve all over the world. The important note that bioaccumulation of B from irrigation water was first analyzed for first time in a risk assessment study using a Lemna species exposed to various B concentrations. Boron toxicity was evaluated through plant growth and biomass production during phytoremediation process. The result from the present experiment indicated that L. gibba was capable of removing 19-63% B from irrigation water depending upon contaminated level or initial concentration. We also found that B was removed from aqueous solution following pseudo second order kinetic model and Langmuir isotherm model better fitted equilibrium obtained for B phytoremediation. Maximum B accumulation in L. gibba was determined as 2088mgkg -1 at average inflow B concentration 17.39mgL -1 at the end of the experiment. Conversely, maximum bioconcentration factor obtained at lowest inflow B concentrations were 232 for L. gibba. The present study suggested that L. gibba was very useful B accumulator, and thus L. gibba-based techniques could be a reasonable phytoremediation option to remove B directly from water sources contaminated with B. Copyright © 2016 Elsevier B.V. All rights reserved.

Effects of low SO/sub 2/ concentrations on the mitotic activity and on the cell cycle of duckweed (Lemna minor L. )

Energy Technology Data Exchange (ETDEWEB)

Stoeckli, B; Braendle, R; Erismann, K H

1975-01-01

Duckweed (Lemena minor) has proven to be a suitable indicator for the effects of low SO/sub 2/ concentrations. Therefore, this plant was used to study the mitotic activity as well as the cell cycle under fumigation with sublethal SO/sub 2/ concentrations although to a great extent the morphology of this plant is still unknown. It is also difficult to process this plant cytologically.

Biofuel Production: Considerations for USACE Civil Works Business Lines

Science.gov (United States)

2014-12-01

feedstock for biofuel production has led to research whereby several genera of duckweed ( Lemna , Landoltia, Spirodela, Wolffia, Wolfiella) have been...as well as the general public when rendering its final permit decisions. Regulatory responsibilities include evaluating minor activities such as...reservoirs scattered along minor river systems in other parts of the United States (Kasul et al. 1998) Through a series of legislative acts in the

Exogenous salicylate application affects the lead and copper accumulation characteristics of Lemna gibba L.

Energy Technology Data Exchange (ETDEWEB)

Duman, Fatih; Aksoy, Ahmet; Ozturk, Fatma; Ceylan, Ahmet [Erciyes Univ., Kayseri (Turkey). Dept. of Biology

2010-11-15

Previous studies have shown that salicylates can change the ion permeability of root cells. Therefore the possible effects of exogenous salicylate application on lead (Pb) and copper (Cu) accumulation and its protective role against DNA damage due to metal exposure in Lemna gibba were studied. L. gibba was exposed to 5, 10, and 25 {mu}M Pb and Cu for six days in the presence and absence of sodium salicylate (SA) (0.1, 0.5, and 1 mM). At all concentrations tested, SA application decreased Pb accumulation. On the other hand, application of 0.5 mM SA increased Cu accumulation. SA did not reduce DNA damage resulting from Pb and Cu toxicity. In summary, SA may be useful for reducing Pb accumulation, and application of SA at 0.5 mM may be useful for the phytoextraction of Cu. (orig.)

Early adolescent music preferences and minor delinquency.

Science.gov (United States)

Ter Bogt, Tom F M; Keijsers, Loes; Meeus, Wim H J

2013-02-01

To test Music Marker Theory (MMT) positing that early adolescents' preferences for nonmainstream types of popular music indicate concurrent and later minor delinquency. MMT was tested in a 4-year longitudinal study (n = 309). The results showed that early fans of different types of rock (eg, rock, heavy metal, gothic, punk), African American music (rhythm and blues, hip-hop), and electronic dance music (trance, techno/hardhouse) showed elevated minor delinquency concurrently and longitudinally. Preferring conventional pop (chart pop) or highbrow music (classic music, jazz), in contrast, was not related to or was negatively related to minor delinquency. Early music preferences emerged as more powerful indicators of later delinquency rather than early delinquency, indicating that music choice is a strong marker of later problem behavior. The mechanisms through which music preferences are linked to minor delinquency are discussed within the framework of MMT.

Real-time visualization of oxidative stress in a floating macrophyte Lemna minor L. exposed to cadmium, copper, menadione, and AAPH.

Science.gov (United States)

Razinger, Jaka; Drinovec, Luka; Zrimec, Alexis

2010-12-01

An ultra-sensitive digital imaging system was employed to visualize oxidative stress in intact L. minor plants exposed to Cd, Cu, menadione, AAPH, and ascorbate in real time. The increase of ROS production was assessed by measuring the rate of fluorescence intensity increases of the test medium supplemented with a fluorescing probe (dichlorofluorescein diacetate). The addition of 100 μM CdCl₂ or 100 μM CuSO₄ to the growth medium resulted in a significant increase of medium fluorescence. Additionally, CuSO₄ caused a significantly higher fluorescence intensity than CdCl₂ did. A strong positive correlation (R² = 0.99) between menadione concentration and fluorescence intensity was observed. The positive correlation between AAPH concentration and fluorescence intensity was not as strong as in the case of menadione (R² = 0.81). Menadione induced a stronger oxidative stress than similar concentration of AAPH. The addition of 100 μM ascorbate to L. minor treated with 50 μM menadione significantly reduced the fluorescence intensity increase. A linear trend of the fluorescence increase was observed in all treatments, indicating that chemical-induced oxidative stress is a gradual process and that the applied concentrations of the chemicals caused a constant increased production of ROS with different intensities, depending on the treatment. This is the combined result of a gradual diminishing of antioxidant reserves and accumulating oxidative damage. The observed rates of ROS production were slower than those in the studies using cell cultures. Copyright © 2009 Wiley Periodicals, Inc.

The maximization of the productivity of aquatic plants for use in controlled ecological life support systems (CELSS)

Science.gov (United States)

Thompson, B. G.

Lemna minor (common duckweed) and a Wolffia sp. were grown in submerged growth systems. Submerged growth increased the productivity/unit volume (P/UV) of the organisms and may allow these plants to be used in a controlled ecological life support system (CELSS).

三苯基锡对青萍生长及酶活性的影响%Toxic Effects of Triphenyltin on the Growth and the Related Enzymic Activities of Lemna minor

Institute of Scientific and Technical Information of China (English)

宋志慧; 刘歌

2010-01-01

以青萍(Lemna mino)为实验生物,通过研究不同浓度(0、0.04、0.08、0.12、0.16、0.20mg·L-1)的三苯基锡(TPT)对青萍生长发育及过氧化氢酶(CAT)和过氧化物酶(POD)活性的影响,初步探讨了TPT对水生浮萍植物的毒性作用,以期为及时发现并排除TPT污染提供理论和直观依据.实验结果表明:培养4d后,TPT对青萍叶片生长量的半数抑制浓度(IC50)为0.10mg·L-1;CAT、POD活性随TPT处理浓度的升高显著升高(各暴露组与对照组均差异显著,p＜0.05).结果显示,TPT对青萍具有明显的毒性作用,CAT和POD活性的变化可作为反映TPT污染胁迫的敏感指标.

Uptake of acidic and basic sugar derivatives in Lemna gibba G1

International Nuclear Information System (INIS)

Sanz, A.; Ullrich, C.I.

1989-01-01

The uptake of acidic and basic sugar derivatives in Lemna gibba L. was studied. Uronic acids applied to the experimental solution induced a small decrease of the membrane potential. After incubation of the plants in a 0.1 millimolar solution of these substrates, no decrease in the concentration of reducing groups in the external solution was detected. Respiration increased by 31% with 50 millimolar galacturonic acid, whereas no effect was found with the same concentration of glucuronic acid. Glucosamine caused a considerable concentration-dependent membrane depolarization. ( 14 C)glucosamine uptake followed Michaelis-Menten kinetics together with a linear component. Influx of this substrate was inhibited by glucose but the type of competition could not be clearly distinguished. Glucosamine, 50 millimolar, inhibited the respiration rate by 30%. The glucosamine uptake was pH-dependent, with maximum uptake at around pH 7. Lack of enhancement of uptake by low pH as well as the permanent membrane depolarization suggest a uniport mechanism for the charged species of the substrate and an electroneutral diffusion of the uncharged species

Pb-induced avoidance-like chloroplast movements in fronds of Lemna trisulca L.

Directory of Open Access Journals (Sweden)

Sławomir Samardakiewicz

Full Text Available Lead ions are particularly dangerous to the photosynthetic apparatus, but little is known about the effects of trace metals, including Pb, on regulation of chloroplast redistribution. In this study a new effect of lead on chloroplast distribution patterns and movements was demonstrated in mesophyll cells of a small-sized aquatic angiosperm Lemna trisulca L. (star duckweed. An analysis of confocal microscopy images of L. trisulca fronds treated with lead (15 μM Pb2+, 24 h in darkness or in weak white light revealed an enhanced accumulation of chloroplasts in the profile position along the anticlinal cell walls, in comparison to untreated plants. The rearrangement of chloroplasts in their response to lead ions in darkness was similar to the avoidance response of chloroplasts in plants treated with strong white light. Transmission electron microscopy X-ray microanalysis showed that intracellular chloroplast arrangement was independent of the location of Pb deposits, suggesting that lead causes redistribution of chloroplasts, which looks like a light-induced avoidance response, but is not a real avoidance response to the metal. Furthermore, a similar redistribution of chloroplasts in L. trisulca cells in darkness was observed also under the influence of exogenously applied hydrogen peroxide (H2O2. In addition, we detected an enhanced accumulation of endogenous H2O2 after treatment of plants with lead. Interestingly, H2O2-specific scavenger catalase partly abolished the Pb-induced chloroplast response. These results suggest that H2O2 can be involved in the avoidance-like movement of chloroplasts induced by lead. Analysis of photometric measurements revealed also strong inhibition (but not complete of blue-light-induced chloroplast movements by lead. This inhibition may result from disturbances in the actin cytoskeleton, as we observed fragmentation and disappearance of actin filaments around chloroplasts. Results of this study show that the

Phenol toxicity to the aquatic macrophyte Lemna paucicostata

Energy Technology Data Exchange (ETDEWEB)

Park, Ji-Sook [Division of Life Science, University of Incheon, Incheon 406-840 (Korea, Republic of); Brown, Murray T. [School of Marine Science and Engineering, University of Plymouth, Plymouth, Devon PL4 8AA (United Kingdom); Han, Taejun, E-mail: hanalgae@hanmail.net [Division of Life Science, University of Incheon, Incheon 406-840 (Korea, Republic of); Institute of Green Environmental Research, University of Incheon, Incheon 406-840 (Korea, Republic of)

2012-01-15

Phenol is a ubiquitous environmental pollutant and a widely used reference toxicant for many bioassays. However, little information is available regarding the toxic effects of phenol on aquatic macrophytes. Seventy-two hour bioassays, with different end-points, were carried out to assess phenol toxicity in Lemna paucicostata. A concentration-dependent decline in frond multiplication and colony disintegration was observed, with 11.38 and 22.76 {mu}M phenol resulting in browning of fronds and colony disintegration, respectively. Growth of fronds, as measured by changes in surface area, was significantly inhibited with EC{sub 50} value of 2.70 {mu}M. When pulse amplitude modulated chlorophyll a (Chl a) fluorescence imaging (i-PAM) was employed, the maximum quantum yield of PS II (F{sub v}/F{sub m}) significantly declined with increasing phenol concentrations with resultant EC{sub 50} of 1.91 {mu}M and coefficients of variation (CVs) generated for the EC{sub 50} values of less than 4.7%. A gradual increase in fluorescence emissions from chlorophylls a and b and pheophytin up to a concentration of 2.85 {mu}M was found but declined markedly at higher concentrations. The significant correlation between the F{sub v}/F{sub m} and surface growth rate data implies that the former is an appropriate biomarker of whole plant toxicity. Using imaging Chl a fluorescence on L. paucicostata provides a rapid, sensitive and reliable method for assessing the toxic risks posed by phenol to aquatic ecosystems and has practical applications for municipal and industrial waste water management.

Phenol toxicity to the aquatic macrophyte Lemna paucicostata

International Nuclear Information System (INIS)

Park, Ji-Sook; Brown, Murray T.; Han, Taejun

2012-01-01

Phenol is a ubiquitous environmental pollutant and a widely used reference toxicant for many bioassays. However, little information is available regarding the toxic effects of phenol on aquatic macrophytes. Seventy-two hour bioassays, with different end-points, were carried out to assess phenol toxicity in Lemna paucicostata. A concentration-dependent decline in frond multiplication and colony disintegration was observed, with 11.38 and 22.76 μM phenol resulting in browning of fronds and colony disintegration, respectively. Growth of fronds, as measured by changes in surface area, was significantly inhibited with EC 50 value of 2.70 μM. When pulse amplitude modulated chlorophyll a (Chl a) fluorescence imaging (i-PAM) was employed, the maximum quantum yield of PS II (F v /F m ) significantly declined with increasing phenol concentrations with resultant EC 50 of 1.91 μM and coefficients of variation (CVs) generated for the EC 50 values of less than 4.7%. A gradual increase in fluorescence emissions from chlorophylls a and b and pheophytin up to a concentration of 2.85 μM was found but declined markedly at higher concentrations. The significant correlation between the F v /F m and surface growth rate data implies that the former is an appropriate biomarker of whole plant toxicity. Using imaging Chl a fluorescence on L. paucicostata provides a rapid, sensitive and reliable method for assessing the toxic risks posed by phenol to aquatic ecosystems and has practical applications for municipal and industrial waste water management.

Regional Supplement to the Corps of Engineers Wetland Delineation Manual: Great Plains Region (Version 2.0)

Science.gov (United States)

2010-03-01

These wetlands range from temporarily to permanently inundated and may be dominated by floating-leaved plants in deeper areas (e.g., Lemna ...more than one soil type or component. They often contain several minor components or inclusions of soils with properties that may be similar to or

An attempt to electrically enhance phytoremediation of arsenic contaminated water

NARCIS (Netherlands)

Kubiak, J.J.; Khankhane, P.J.; Kleingeld, P.J.; Lima, A.T.

2012-01-01

Water polluted with arsenic presents a challenge for remediation. A combination of phyto- and electro-remediation was attempted in this study. Four tanks were setup in order to assess the arsenic removal ability of the two methods separately and in combination. Lemna minor was chosen for As

The Screening of Culture Method for Lemna%浮萍培养方法的筛选

Institute of Scientific and Technical Information of China (English)

孙源; 曹凯文; 王仁君; 丁宁; 曹泰; 张萍; 李青竹; 赵熙宇; 崔萍; 李亚琪; 赵翔宇

2017-01-01

Under laboratory conditions,duckweed as the research obj ect,we tested 3 common ways to culture Lemna-6-well plates,culture dishes and glass beakers.With laboratory experiments of batch cul-ture,the growth curves of Lemna were gotten and fitted by Logistic model.Specifically we examinated bio-mass、the content of protein、the content of chlorophyll and Fv/Fm .This results showed that:(1 )The growth curve has characteristic of sigmoidal shape and the growth rate has density-dependent characteris-tic.The value of r and k of Lemna in glass beakers is above 6-well plates and culture dishes.(2)In culture dishes of duckweed Fv/Fm is greater than glass beakers is greater than 6-well plates.(3)In glass beakers of duckweed chlorophyll is greater than 6-well plates is greater than culture dishes .(4)In glass beakers of duckweed protein is greater than 6-well plates is greater than culture dishes .So the beaker cultivation method of duckweed works best under laboratory conditions.It suggests that how to culture duckweed un-der laboratory.%在实验室条件下，以青萍为研究对象，比较了3种较为常见的室内浮萍培养方法———六孔板培养法，培养皿培养法，烧杯培养法。该研究采用序批式培养方式培养青萍，利用单种种群增长的 Logistic 模型对生物量的增长曲线进行了分析，同时测定了青萍的生物量、蛋白质含量、叶绿素含量、PSII 最大光化学效率(Fv/Fm )等生理指标。结果表明：(1)青萍的生物量随时间变化的增长曲线呈典型的“S”型，在特定的环境和营养条件下，单位面积上青萍生物量的增长受密度的制约。其中，烧杯培养的青萍的 r值和K值>六孔板>培养皿。(2)烧杯培养的青萍的Fv/Fm 值>六孔板>培养皿。(3)烧杯培养的青萍叶绿素含量>六孔板>培养皿。(4)�

Compostaje de residuos orgánicos y de lenteja de agua (Lemna SP.) con aplicación microorganismos eficaces

OpenAIRE

Suaña Quispe, María Elena

2013-01-01

El estudio se realizó en el Departamento de Puno, Perú; en las instalaciones del laboratorio de Biología de la Facultad de Ciencias Biológicas durante los meses de Octubre a Diciembre del 2012, con el fin de elaborar compost a partir de residuos orgánicos domésticos y Lenteja de agua (Lemna spp.) aplicando microorganismos eficaces (EM) a tres dosis (0, 100 y 200 mi) se evaluó el tiempo de descomposición y granulometría, temperatura, pH, nitrógeno, fósforo, potasio y sodio. Se utilizó el análi...

Stable isotope labeling, in vivo, of D- and L-tryptophan pools in lemna gibba and the low incorporation of label into indole-3-acetic acid

International Nuclear Information System (INIS)

Baldi, B.G.; Maher, B.R.; Slovin, J.P.; Cohen, J.D.

1991-01-01

The authors present evidence that the role of tryptophan and other potential intermediates in the pathways that could lead to indole derivatives needs to be reexamined. Two lines of Lemna gibba were tested for uptake of [ 15 N-indole]-labeled tryptophan isomers and incorporation of that label into free indole-3-acetic acid (IAA). Both lines required levels of L-[ 15 N]tryptophan 2 to 3 orders of magnitude over endogenous levels in order to obtain measurable incorporation of label into IAA. Labeled L-tryptophan was extractable from plant tissue after feeding and showed no measurable isomerization into D-tryptophan. D-[ 15 N]trytophan supplied to Lemna at rates of approximately 400 times excess of endogenous D-tryptophan levels (to yield an isotopic enrichment equal to that which allowed detection of the incorporation of L-tryptophan into IAA), did not result in measurable incorporation of label into free IAA. These results demonstrate that L-tryptophan is a more direct precursor to IAA than the D isomer and suggest (a) that the availability of tryptophan in vivo is not a limiting factor in the biosynthesis of IAA, thus implying that other regulatory mechanisms are in operation and (b) that L-tryptophan also may not be a primary precursor to IAA in plants

Photosynthesis under low-level SO/sub 2/ and CO/sub 2/ enhancement conditions in three duckweed species

Energy Technology Data Exchange (ETDEWEB)

Loats, K V [Denison Univ., Granville, OH; Noble, R; Takemoto, B

1981-09-01

Following exposure to 0.5 and 0.75 ppm SO/sub 2/ fumigation for up to 2 wk, apparent photosynthesis was determined in Lemna minor, L. valdiviana, and Spirodela oligorhiza by infrared gas analysis at 300, 500, and 1,000 ppm CO/sub 2/. Net photosynthesis was inhibited in L. valdiviana and S. oligorhiza but not in L. minor. The growth rate, as measured by frond count, was not affected in L. minor and L. valdiviana and only slightly in S. oligorhiza. Short-term CO/sub 2/ enhancement appreciably increased the photosynthetic rates.

Characterization of a chlorophyll b-less mutant of Lemna gibba G3

International Nuclear Information System (INIS)

Slovin, J.P.

1987-01-01

Nitrosomethylurea mutagenesis of whole plants of duckweed, Lemna gibba G3, produced many plants with various types of obvious pigment abnormalities. One such plant is yellow-green and has a chlorophyll a/b ratio of 8. Spectra from plants grown in white light show a prominent absorption peak at 472 nm, that is not present in spectra from wild type plants. This peak is present, however, when wild type plants are grown under red light conditions. B-less plants accumulate some chlorophyll b under some light conditions and depending on the age of the plants. SDS-PAGE of proteins in thylakoid membranes and in a soluble fraction show that the only obvious band missing corresponds to the LHCP. Preliminary data from 35 S methionine in vivo labeling indicate that there is some LHCP being synthesized in these plant, however the identity of the labeled bands is only now being established using antibodies, and the amount of labeled material does not appear to be the same as in the wild type. The author is currently doing the genetics on this variant and are interested in determining whether the b-less phenotype results from a mutation involving synthesis of the LHCP

comparative study on the efficiency of Lemna minor L.

African Journals Online (AJOL)

Science World Journal Vol 10 (No 3) 2015 ... Pistiastratiotes In The Phytoremediation Of Refinery Waste Water. COMPARATIVE ... treatment to help in the determination of percentage ... research shows that Lemnaminoris the best plant to be.

Inhibition of flowering in the long-day plant Lemna gibba G3 by Hutner's medium and its reversal by salicyclic acid

Energy Technology Data Exchange (ETDEWEB)

Tanaka, O [Smithsonian Institution Radiation Biology Lab., Rockville, MD; Cleland, C F; Hillman, W S

1979-01-01

Flowering in the long-day plant Lemna gibba L., strain G3 is poor or absent in Hutner's medium even under continuous light, an effect generally ascribed to the ammonium content of the medium. However, flowering is also inhibited in ammonium-free modifications of Hutner's medium, particularly in the presence of sucrose, but is restored to high levels by the presence of 10 ..mu..M salicylic acid. These results link two of the least understood chemical effects in Lemnaceae flowering, and they provide a system in which large effects of salicylic acid can be readily obtained.

Minority heating scenarios in and SST-1 plasmas

Indian Academy of Sciences (India)

Asim Kumar Chattopadhyay

2017-12-19

Dec 19, 2017 ... ... it has been observed that minority ion heating is the principal heating mechanism compared to electron ..... (∂Fi/∂t)QL has a strong pitch angle, μ, dependence. ..... related to complex change in elements of dielectric ten-.

泽漆水浸液及茶皂素浸提液对浮萍的抑制效果%Study on the inhibitory effect of Euphorbia helioscopia L.aqueous extract with and without tea saponin on Lemna minor L.

Institute of Scientific and Technical Information of China (English)

张乐婷; 张饮江; 张曼曼; 金晶; 陈晓君; 段婷; 王芳

2014-01-01

通过对浮萍表观生长状态的观察记录以及对其抗氧化酶、丙二醛含量的测定,研究泽漆水浸液对浮萍(Lemna minor L.)的抑制活性,并探索利用茶皂素作为浸提辅助剂,检测是否提高泽漆对浮萍的抑制作用.结果表明:低浓度泽漆水浸液(0.001、0.003、0.005 g/mL)胁迫下,浮萍部分抗氧化酶系统遭受破坏,过氧化氢酶、过氧化物酶活性下降,超氧化物歧化酶活性先升高后降低,未出现明显表观受伤症状;高浓度泽漆水浸液(0.01、0.015、0.02 g/mL)胁迫36 h,90％～100％个体受伤严重甚至死亡,受伤个体、程度与浓度、时间成正比,茶皂素助浸液胁迫36 h时,出现明显受伤症状的个体数≤10％.茶皂素作为浸提辅助剂所得泽漆浸提液没有加强对浮萍的抑制作用,反而减弱了这种作用.泽漆水浸液对浮萍有明显的抑制作用,今后可进一步分析泽漆水浸液和其茶皂素助浸液之间化学成分种类和含量的差异,这有助于抑制浮萍有效成分的鉴定.

Uptake characteristics of nitrate and phosphate by Lemna minor L.%青萍(Lemna minor L.)对氮磷的吸收特征

Institute of Scientific and Technical Information of China (English)

刘明; 黄磊; 杜刚; 郭劲松; 高旭

2013-01-01

以西部地区优势浮萍品种青萍为实验对象,研究了青萍对不同浓度硝态氮和磷酸盐的吸收特征.结果表明,硝态氮浓度在1 ～ 10 mg/L范围内,青萍对硝态氮有较好的吸收效果,M-M方程可以较好地描述硝态氮浓度与青萍对硝态氮的吸收速率之间的关系,通过M-M方程拟合得到青萍对硝态氮的最大吸收速率为0.1167 mg/(g FW·h),亲和力常数为6.9274.磷酸盐浓度在0.1～1.0 mg/L范围内,青萍对磷酸盐也有较好的吸收效果,二次多项式回归可以较好地描述青萍吸收速率与磷酸盐浓度的关系,回归方程得到青萍对磷酸盐的最大吸收速率为0.0193 mg/(g FW·h),对应磷酸盐浓度为0.6 mg/L.

Evaluación del postratamiento de aguas residuales municipales mediante la utilización de macrofitas como las lentejas de agua (lemma minor en lagunas de estabilización.

Directory of Open Access Journals (Sweden)

Juan Pablo Rodriguez Miranda

2018-04-01

Full Text Available El presente artículo, tiene el propósito de determinar la utilidad de la lenteja de agua (lemna minor como postratamiento en lagunas de estabilización que tratan aguas residuales domésticas, fue analizada una muestra de agua residual proveniente del efluente de la laguna anaerobia del sistema de tratamiento de aguas residuales el Salguero de Valledupar-Cesar; la muestra fue inoculada con las lentejas de agua, las cuales fueron tomadas de reservorios ubicados en las afueras del Municipio en mención. Se realizó el montaje empleando un sistema tipo batch a escala laboratorio con tres replicas y dos controles los parámetros analizados fueron nutrientes (nitrógeno y fósforo. La remoción de nutrientes fue: 72% P y 95% N. Se pudo establecer que las lentejas de agua presentan una buena eficiencia en relación a la remoción de nutrientes.

Diferenciación molecular de Lemna aequinoctialis y L. Valdiviana (lemnaceae por patrones proteicos

Directory of Open Access Journals (Sweden)

Mª del Milagro Montero Rojas

2016-03-01

Full Text Available El estudio se llevó a cabo en el Laboratorio de Genética Molecular de la Universidad Nacional, Heredia, Costa Rica. Se utilizaron plantas acuáticas macrófitas de Lemna valdiviana y L. aequinoctialis previamente identificadas. Estas especies habitan en aguas ricas en sales disueltas y aguas servidas. Recientemente se les consideró como un indicador de la contaminación ocasionada por pesticidas y herbicidas en el agua. La composición proteica llega a niveles entre 38 y 43% de materia seca, importante para diversos usos. La extracción de proteínas totales, por medio de electroforesis discontinua en gel de poliacrilamida, se realizó en condiciones reductoras con SDS (SDS-PAGE. Los geles separadores empleados fueron al 8 y 10%, gel espaciador al 4% y la tinción se efectuó con azul commassie. Los diversos patrones proteicos reflejaron diferencias genéticas entre ambas especies que se pueden deber a las diferencias de hábitat y de reproducción.

Effects of light and temperature on duckweed photosynthesis

Energy Technology Data Exchange (ETDEWEB)

Wedge, R M; Burris, J E

1982-06-01

Rates of photosynthesis of Lemna minor L. and Spirodela punctata, two aquatic angiosperms, were measured at different temperatures and light intensities. Photosynthesis was measured both as oxygen evolution and /sup 14/CO/sub 2/ fixation. At temperatures ranging from 15 to 35/sup 0/C, light saturation of photosynthetic O/sub 2/ evolution of Lemna occured from 300-600 ..mu..E m/sup -2/ s/sup -1/, while in Spirodela photosynthetic O/sub 2/ evolution was light saturated at 5600-1200 ..mu..E m/sup -2/ s/sup -1/. Photosynthetic O/sub 2/ evolution of both species was photoinhibited at light intensities greater than 1200 ..mu..E m/sup -2/ s/sup -1/. The optimal temperature for Lemna photosynthetic O/sub 2/ evolution was 30/sup 0/C, while the optimal temperatures for /sup 14/CO/sub 2/ fixation were from 20 to 30/sup 0/C. For Spirodela maximum photosynthetic O/sub 2/, evolution occurred at 35/sup 0/C, while maximum /sup 14/CO/sub 2/ fixation was at 30/sup 0/C.

Minor actinide transmutation using minor actinide burner reactors

International Nuclear Information System (INIS)

Mukaiyama, T.; Yoshida, H.; Gunji, Y.

1991-01-01

The concept of minor actinide burner reactor is proposed as an efficient way to transmute long-lived minor actinides in order to ease the burden of high-level radioactive waste disposal problem. Conceptual design study of minor actinide burner reactors was performed to obtain a reactor model with very hard neutron spectrum and very high neutron flux in which minor actinides can be fissioned efficiently. Two models of burner reactors were obtained, one with metal fuel core and the other with particle fuel core. Minor actinide transmutation by the actinide burner reactors is compared with that by power reactors from both the reactor physics and fuel cycle facilities view point. (author)

Regulatory structure of the biosynthetic pathway for the aspartate family of amino acids in Lemna paucicostata Hegelm. 6746, with special reference to the role of aspartokinase

International Nuclear Information System (INIS)

Giovanelli, J.; Mudd, S.H.; Datko, A.H.

1989-01-01

Comprehensive studies were made with Lemna paucicostate Hegelm. 6746 of the effects of combinations of lysine, methionine, and threonine on growth rates, soluble amino acid contents, aspartokinase activities, and fluxes of 4-carbon moieties from aspartate through the aspartokinase step into the amino acids of the aspartate family. These studies show that flux in vitro through the aspartokinase step is insensitive to inhibition by lysine or threonine, and confirm previous in vitro data in establishing that aspartokinase in vivo is present in two orders of magnitude excess of its requirements. No evidence of channeling of the products of the lysine- and threonine-sensitive aspartokinases was obtained, either form of the enzyme along being more than adequate for the combined in vivo flux through the aspartokinase step. The marked insensitivity of flux through the aspartokinase step to inhibition by lysine or threonine strongly suggests that inhibition of aspartokinase by these amino acids is not normally a major factor in regulation of entry of 4-carbon units into the aspartate family of amino acids. Direct measurement of fluxes of 4-carbon units demonstrated that: (a) Lysine strongly feedback regulates its own synthesis, probably at the step catalyzed by dihydrodipicolinate synthase. (b) Threonine alone does not regulate its own synthesis in vivo, thereby confirming previous studies of the metabolism of [ 14 C]threonine and [ 14 C]homoserine in Lemna

ASSESSMENT OF IMPACT OF COHERENT LIGHT ON RESISTANCE OF PLANTS GROWING IN UNFAVOURABLE ENVIRONMENTAL CONDITIONS

Directory of Open Access Journals (Sweden)

Małgorzata Śliwka

2014-04-01

Full Text Available The results of experiments on the effect of the coherent light emitted by lasers on plant material show that properly selected laser stimulation parameters, such as: wavelength, power, time and type of exposure, allow to obtain a greater growth of plant biomass, changes in the content of elements in the biomass and increasing plant resistance to unfavorable environmental conditions. The aim of this study was to determine the effect of laser stimulation on selected plant species (Iris pseudoacorus L., Lemna minor L. to increase their resistance to low temperatures and the ability to adapt to an environment polluted by mining activities (Phelum pratense L.. Plants from experimental groups (Iris pseudoacorus L., Phelum pratense L., Lemna minor L. were stimulated with coherent light with specific characteristics. To irradiate plants from experimental groups different algorithms of stimulation parameters, differentiating the method and time of exposure were used. Plants group without the stimulation, were the reference group. The article discusses the results of preliminary experiments carried out on a laboratory scale and pot experiments.

Analytical procedures for bulk frozen-hydrated biological tissues

International Nuclear Information System (INIS)

Echlin, P.; Hayes, T.L.; McKoon, M.

1983-01-01

The main advantage of using solid frozen samples for elemental x-ray microanalysis is the ease with which they may be prepared and maintained in the frozen-hydrated state. Within the limits imposed by the reduced spatial resolution of the method, the morphological identification of the tissue components is comparatively easy. Bearing in mind these limitations, the authors have carried out an analysis for several elements in the developing root tips of Lemna minor L (Duckweed). Fresh root tips of Lemna minor L, briefly encapsulated in a polymeric cryoprotectant, are quench frozen in melting nitrogen at ca. 70 0 K and transferred to the pre-cooled cold stage of an AMray Biochamber. The analysis was carried out by means of a Kevex energy-dispersive detector by use of the peak-to-background ratio method. These procedures allow the authors to obtain flat fracture faces in which they have been able to measure the relative concentrations of various elements at the various stages of differentiation in the root tissue

Competition between Free-Floating Plants Is Strongly Driven by Previously Experienced Phosphorus Concentrations in the Water Column.

Science.gov (United States)

Peeters, Edwin T H M; Neefjes, Rozemarijn E M; Zuidam, Bastiaan G van

2016-01-01

Nutrients can determine the outcome of the competition between different floating plant species. The response of floating plants to current phosphorus levels may be affected by previously experienced phosphorus concentrations because some species have the ability to store excess phosphorus for later use. This might have an impact on their competition. Here, we investigate the effect of previous and actual phosphorus concentrations on the growth rate of free-floating plant species (Azolla filiculoides, Lemna minor/gibba and Ricciocarpus natans)and the effect of phosphorus history on the competition between L. minor/gibba and A. filiculoides and between L. minor/gibba and R. natans. As expected, plant growth was lower when previously kept at low instead of high phosphorus concentrations. Growth of L. minor/gibba and A. filiculoides with a phosphorus rich history was comparable for low and high actual phosphorus concentrations, however, internal phosphorus concentrations were significantly lower with low actual phosphorus concentration. This indicates that both species perform luxury phosphorus uptake. Furthermore, internal P concentration in Azolla and Lemna increased within two weeks after a period of P deficit without a strong increase in growth. A. filiculoides in a mixture with L. minor/gibba grew faster than its monoculture. Morphological differences may explain why A. filiculoides outcompeted L. minor/gibba and these differences may be induced by phosphorus concentrations in the past. Growth of L. minor/gibba was only reduced by the presence of A. filiculoides with a high phosphorus history. Growth of L. minor/gibba and R. natans in mixtures was positively affected only when they had a high phosphorus history themselves and their competitor a low phosphorus history. These observations clearly indicate that phosphorus history of competing plants is important for understanding the outcome of the competition. Therefore, actual and previously experienced phosphorus

Electronic Cigarette Refill Liquids: Child-Resistant Packaging, Nicotine Content, and Sales to Minors.

Science.gov (United States)

Buettner-Schmidt, Kelly; Miller, Donald R; Balasubramanian, Narayanaganesh

2016-01-01

To determine the accuracy of the labeled quantity of the nicotine content of the e-liquids sold in unlicensed vape stores, whether the packaging of e-liquids sold within the vape stores was child-resistant, whether minors were present within vape stores, and whether sales to minors occurred. This study was conducted across North Dakota prior to implementation of a new e-cigarette state law and provided a baseline assessment before enactment of the new legal requirements. We tested samples of e-liquids and performed observations in 16 stores that were selling e-cigarettes but were not legally required to be licensed for tobacco retail. The e-liquids were analyzed for nicotine content using a validated high-performance liquid chromatography method for nicotine analysis. Of the 70 collected e-liquid samples that claimed to contain nicotine, 17% contained more than the labeled quantity and 34% contained less than the labeled quantity by 10% or more, with one sample containing 172% more than the labeled quantity. Of the 94 e-liquid containers sampled, only 35% were determined to be child-resistant. Minors were present in stores, although no sales to minors occurred. Mislabeling of nicotine in e-liquids is common and exposes the user to the harmful effects of nicotine. The lack of child-resistant packaging for this potentially toxic substance is a serious public health problem. E-cigarettes should be included in the legal definition of tobacco products, child-resistant packaging and nicotine labeling laws should be enacted and strictly enforced, and vape stores should be licensed by states. Copyright © 2016 Elsevier Inc. All rights reserved.

Minority Language Rights.

Science.gov (United States)

O Riagain, Padraig; Shuibhne, Niamh Nic

1997-01-01

A survey of literature since 1990 on minority languages and language rights focuses on five issues: definition of minorities; individual vs. collective rights; legal bases for minority linguistic rights; applications and interpretations of minority language rights; and assessments of the impact of minority rights legislation. A nine-item annotated…

Multiple Minority Stress and LGBT Community Resilience among Sexual Minority Men.

Science.gov (United States)

McConnell, Elizabeth A; Janulis, Patrick; Phillips, Gregory; Truong, Roky; Birkett, Michelle

2018-03-01

Minority stress theory has widespread research support in explaining health disparities experienced by sexual and gender minorities. However, less is known about how minority stress impacts multiply marginalized groups, such as lesbian, gay, bisexual, and transgender people of color (LGBT POC). Also, although research has documented resilience in the face of minority stress at the individual level, research is needed that examines macro-level processes such as community resilience (Meyer, 2015). In the current study, we integrate minority stress theory and intersectionality theory to examine multiple minority stress (i.e., racial/ethnic stigma in LGBT spaces and LGBT stigma in one's neighborhood) and community resilience (i.e., connection to LGBT community) among sexual minority men of different racial/ethnic groups who use a geosocial networking application for meeting sexual partners. Results showed that Black sexual minority men reported the highest levels of racial/ethnic stigma in LGBT spaces and White sexual minority men reported the lowest levels, with Asian and Hispanic/Latino men falling in between. Consistent with minority stress theory, racial/ethnic stigma in LGBT spaces and LGBT stigma in one's neighborhood were associated with greater stress for sexual minority men of all racial/ethnic groups. However, connection to LGBT community played more central role in mediating the relationship between stigma and stress for White than POC sexual minority men. Results suggest that minority stress and community resilience processes may differ for White and POC sexual minority men. Potential processes driving these differences and implications for minority stress theory are discussed.

Uptake of Different Forms of Nitrogen and Phosphorus by Three Aquatic Plants%3种水生植物对不同形态氮·磷吸收的研究

Institute of Scientific and Technical Information of China (English)

杨小霞; 黄晓典; 赵超; 彭少华; 韩磊

2012-01-01

[目的]探讨水蓼、浮萍和黑藻在水体氮、磷去除中的应用价值.[方法]在室内培养条件下,比较这3种水生植物对不同形态和浓度氮、磷的吸收效果.[结果]3种植物发挥最大N、P吸收效果的水体N、P浓度分别为1和5 mg/L.经10 d的培养,3种水生植物对铵态氮和硝态氮的去除率均达50％以上,其中浮萍对铵态氮的去除率高达63.6％；3种水生植物对磷的去除以正磷酸盐最佳,焦磷酸盐次之,偏磷酸盐最差.浮萍对这3种形态磷的去除效果均最好,去除率分别为94.7％、85.6％和70.9％.[结论]浮萍可以作为一种净化植物,可以有效地降低水中铵态氮和不同形态磷浓度.%[Objective]The nitrogen and phosphorus absorption in water by Polygonum hydropiper L. , Hydrilla verticillata (L. f. ) Royle and Lemna minor L. were studied. [Method]The uptake of nitrogen and phosphorus with different forms and concentrations by three aquatic plants was evalulated under laboratary conditions. [Result]The concentrations of N and P in water which made the plants achieve the hightest uptake of the two elements were 1 and 5 mg/L, respectively. The removal rates of NH4-N and N03-N by three plants were over 50% after 10 days treatment, and the highest removal rate (63.6% ) for NH4-N was found in Lemna minor L. Among the different forms of phosphorus, the removal efficiency by plants was followed as orthophosphate > pyrophosphate > metaphosphate. Lemna minor L. had the best removal rate for three forms of phosphorus, with a removal rate of 94.7% , 85.6% and 70.9% , respectively. [Conclusion]Lemna minor L. was an idea plant for efficient removal of NH4-N and different forms of phosphorus in water.

Measuring minority-carrier diffusion length using a Kelvin probe force microscope

International Nuclear Information System (INIS)

Shikler, R.; Fried, N.; Meoded, T.; Rosenwaks, Y.

2000-01-01

A method based on Kelvin probe force microscopy for measuring minority-carrier diffusion length in semiconductors is described. The method is based on measuring the surface photovoltage between the tip of an atomic force microscope and the surface of an illuminated semiconductor junction. The photogenerated carriers diffuse to the junction and change the contact potential difference between the tip and the sample, as a function of the distance from the junction. The diffusion length L is then obtained by fitting the measured contact potential difference using the minority-carrier continuity equation. The method was applied to measurements of electron diffusion length in GaP pn and Schottky junctions. The measured diffusion length was found to be ∼2 μm, in good agreement with electron beam induced current measurements

Diminished Mercury Emission From Water Surfaces by Duckweed (Lemna minor)

Science.gov (United States)

Wollenberg, J. L.; Peters, S. C.

2007-12-01

Aquatic plants of the family Lemnaceae (generally referred to as duckweeds) are a widely distributed type of floating vegetation in freshwater systems. Under suitable conditions, duckweeds form a dense vegetative mat on the water surface, which reduces light penetration into the water column and decreases the amount of exposed water surface. These two factors would be expected to reduce mercury emission by limiting a) direct photoreduction of Hg(II), b) indirect reduction via coupled DOC photooxidation-Hg(II) reduction, and c) gas diffusion across the water-air interface. Conversely, previous studies have demonstrated transpiration of Hg(0) by plants, so it is therefore possible that the floating vegetative mat would enhance emission via transpiration of mercury vapor. The purpose of this experiment was to determine whether duckweed limits mercury flux to the atmosphere by shading and the formation of a physical barrier to diffusion, or whether it enhances emission from aquatic systems via transpiration of Hg(0). Deionized water was amended with mercury to achieve a final concentration of approximately 35 ng/L and allowed to equilibrate prior to the experiment. Experiments were conducted in rectangular polystyrene flux chambers with measured UV-B transmittance greater than 60% (spectral cutoff approximately 290 nm). Light was able to penetrate the flux chamber from the sides as well as the top throughout the experiment, limiting the effect of shading by duckweed on the water surface. Flux chambers contained 8L of water with varying percent duckweed cover, and perforated plastic sheeting was used as an abiotic control. Exposures were conducted outside on days with little to no cloud cover. Real time mercury flux was measured using atomic absorption (Mercury Instruments UT-3000). Total solar and ultraviolet radiation, as well as a suite of meteorological parameters, were also measured. Results indicate that duckweed diminishes mercury emission from the water surface as compared to open water controls. Decreases in emission rate varied linearly with percent duckweed cover, with lower fluxes occurring at higher percent cover. Mercury flux in the duckweed treatments as compared to open water treatments decreased from 17% in the lowest percent cover treatment to 67% in the highest percent cover treatment. The observed decrease in mercury emission suggests that duckweed limits emission via the formation of a physical barrier to diffusion.

Influence of pH, light cycle, and temperature on ecotoxicity of four sulfonylurea herbicides towards Lemna gibba

DEFF Research Database (Denmark)

Rosenkrantz, Rikke Tjørnhøj; Cedergreen, Nina; Baun, Anders

2013-01-01

test conditions on the toxicity of four sulfonylurea herbicides (SUs). The toxicity of the four SUs towards Lemna gibba was investigated at three pH levels (6, 7.5 and 9), at two temperatures (15 and 24 °C) and two light regimes (continuous and 12:12 h light:dark cycle) The EC50 increased twofold...... conditions e.g. specific temperature, pH, light intensity etc. However, environmental conditions under which the organisms live are rarely identical to the standard conditions. Thus, the ecotoxicity of compounds found in standard test is not only a function of the compounds inherent physico...... to tenfold for the four SUs when pH was increased from 6 to 9. Decreasing the temperature from 24 to 15 °C or introducing a dark:light cycle did not cause any trends in changes in toxicity. The results show that test conditions can have an effect on the toxicity and this should be considered when...

Radial diffusion of a minority species in a tokamak due to ICRH

International Nuclear Information System (INIS)

Vacca, L.

1993-01-01

The author studies the transport of a minority species in a scenario where minority ions in a tokamak are heated by fast Alfven waves having a resonance layer in a tokamak. He does not assume the minority distribution function to be a Maxwellian at leading order, as transport theory generally assumes, but adopts a more realistic model where the strong anisotropy of the distribution function is accounted for. This anisotropy has been observed in experiments and is predicted by numerical calculations based on Fokker-Planck equation with quasilinear diffusion. By adopting a different ordering from that used in previous work on transport due to waves and taking moments of the kinetic equation which includes the rf driving term, he calculates the fluxes of the resonant minority species accounting for collisions of minority with bulk electrons and ion species. Finally he makes comparison of fluxes of rf-heated minority with standard neoclassical predictions (no rf source present) showing the enhancement in transport introduced by the presence of both a strongly anisotropic distribution function and an rf source

Observation of minor collapse of current-carrying plasma in LHD

International Nuclear Information System (INIS)

Narushima, Yoshiro; Sakakibara, Satoru; Watanabe, Kiyomasa

2006-01-01

A minor collapse observed in current-carrying plasma has been investigated in Large Helical Device (LHD). The magnetic configuration with high central rotational transform has ι/2π=1 surface at the core region and is relatively unstable for the m/n=1/1 mode (here, m and n are the poloidal and toroidal mode number, respectively). When the beam-driven current exceeds a certain value, the m/n=1/1 mode grows with a growth time of ∼30 ms and causes a sudden drop of the plasma stored energy and the electron temperature, and it also limits the plasma current itself. A local flattening in an electron temperature profile appears just after the minor collapse. The mode does not rotate and stays at the same spatial location. The possibility of pressure- and current-driven magneto-hydro dynamics (MHD) instabilities is discussed. (author)

Использование Ряски малой (Lemna minor) в процессе очистки промышленных стоков золоторудных предприятий в бассейне Р. Амур

OpenAIRE

Гула, К.

2012-01-01

В статье рассматриваются результаты эксперимента по очистке промышленных вод золотодобывающего предприятия с использованием Ряски малой (Lemna minor) из рода Ряска (Lemna L.) семейства рясковые (Lemnactat S.F. Gray). Показано, что степень извлечения ею загрязняющих веществ из сточных вод ЗИФ (золотоизвлекательной фабрики) значительно выше по сравнению с химическим методом, используемым на фабрике.The article discusses the results of the experiment to clean up industrial wastewater gold mining...

镉对浮萍叶绿素荧光参数的影响%Effects of cadmium stress on chlorophyll fluorescence parameters of Lemna mlnor L.

Institute of Scientific and Technical Information of China (English)

李伶; 袁琳; 宋丽娜; 顾詠洁

2010-01-01

以浮萍(Lemna minor L.)为实验材料,使用水下调制荧光仪研究不同镉浓度(0、1、2、4、6、8和10mg-L-1)条件下浮萍叶绿素荧光的变化和叶绿素含量的变化,探讨了镉对浮萍生长和光合作用的影响.结果表明,镉胁迫导致浮萍最大光化学量子产量(Fv/Fm)、光系统Ⅱ(PSⅡ)有效量子产量(φPSⅡ)、光化学淬灭(qP)、相对电子传递速率(rETR)、质体醌库(Fv/2)下降,非光化学淬灭(qN)和PSⅡ水裂解端失活程度(Fv/Fv)上升,说明浮萍的PSⅡ光合活性受到镉胁迫抑制.对浮萍叶绿素含量的测定结果表明.浮萍叶绿索含量明显下降,并且叶绿素a的下降幅度大于叶绿素b;同时,浮萍PSⅡ水裂解程度(Fo/Fv)对于镉胁迫反应极为灵敏,因而可以作为金属胁迫的重要指标.

Electronic Cigarette Refill Liquids: Child-Resistant Packaging, Nicotine Content, and Sales to Minors2

Science.gov (United States)

Buettner-Schmidt, Kelly; Miller, Donald R.; Balasubramanian, Narayanaganesh

2016-01-01

Purpose To determine the accuracy of the labeled quantity of the nicotine content of the e-liquids sold in unlicensed vape stores, whether the packaging of e-liquids sold within the vape stores was child-resistant, whether minors were present within vape stores, and whether sales to minors occurred. This study was conducted across North Dakota prior to implementation of a new e-cigarette state law and provided a baseline assessment before enactment of the new legal requirements. Design and Methods We tested samples of e-liquids and performed observations in 16 stores that were selling e-cigarettes but were not legally required to be licensed for tobacco retail. The e-liquids were analyzed for nicotine content using a validated high-performance liquid chromatography method for nicotine analysis. Results Of the 70 collected e-liquid samples that claimed to contain nicotine, 17% contained more than the labeled quantity and 34% contained less than the labeled quantity by 10% or more, with one sample containing 172% more than the labeled quantity. Of the 94 e-liquid containers sampled, only 35% were determined to be child-resistant. Minors were present in stores, although no sales to minors occurred. Conclusions Mislabeling of nicotine in e-liquids is common and exposes the user to the harmful effects of nicotine. The lack of child-resistant packaging for this potentially toxic substance is a serious public health problem. E-cigarettes should be included in the legal definition of tobacco products, child-resistant packaging and nicotine labeling laws should be enacted and strictly enforced, and vape stores should be licensed by states. PMID:27079973

Uptake and partitioning of zinc in Lemnaceae.

Science.gov (United States)

Lahive, Elma; O'Callaghan, Michael J A; Jansen, Marcel A K; O'Halloran, John

2011-11-01

Macrophytes provide food and shelter for aquatic invertebrates and fish, while also acting as reservoirs for nutrients and trace elements. Zinc accumulation has been reported for various Lemnaceae species. However, comparative accumulation across species and the link between zinc accumulation and toxicity are poorly understood. Morphological distribution and cellular storage, in either bound or soluble form, are important for zinc tolerance. This study shows differences in the uptake and accumulation of zinc by three duckweed species. Landoltia punctata and Lemna minor generally accumulated more zinc than Lemna gibba. L. minor, but not L. gibba or L. punctata, accumulated greater concentrations of zinc in roots compared to fronds when exposed to high levels of zinc. The proportion of zinc stored in the bound form relative to the soluble-form was higher in L. minor. L. punctata accumulated greater concentrations of zinc in fronds compared to roots and increased the proportion of zinc it stored in the soluble form, when exposed to high zinc levels. L. gibba is the only species that significantly accumulated zinc at low concentrations, and was zinc-sensitive. Overall, internal zinc concentrations showed no consistent correlation with toxic effect. We conclude that relationships between zinc toxicity and uptake and accumulation are species specific reflecting, among others, zinc distribution and storage. Differences in zinc distribution and storage are also likely to have implications for zinc bioavailability and trophic mobility.

Effects of a mixture of tetracyclines to Lemna gibba and Myriophyllum sibiricum evaluated in aquatic microcosms

Energy Technology Data Exchange (ETDEWEB)

Brain, Richard A [Centre for Toxicology, Department of Environmental Biology, University of Guelph, Guelph, Ontario, N1G 2W1 (Canada); Wilson, Christian J [Centre for Toxicology, Department of Environmental Biology, University of Guelph, Guelph, Ontario, N1G 2W1 (Canada); Johnson, David J [Centre for Toxicology, Department of Environmental Biology, University of Guelph, Guelph, Ontario, N1G 2W1 (Canada); Sanderson, Hans [Centre for Toxicology, Department of Environmental Biology, University of Guelph, Guelph, Ontario, N1G 2W1 (Canada); Bestari, Ketut [Centre for Toxicology, Department of Environmental Biology, University of Guelph, Guelph, Ontario, N1G 2W1 (Canada); Hanson, Mark L [Centre for Toxicology, Department of Environmental Biology, University of Guelph, Guelph, Ontario, N1G 2W1 (Canada); Sibley, Paul K [Centre for Toxicology, Department of Environmental Biology, University of Guelph, Guelph, Ontario, N1G 2W1 (Canada); Solomon, Keith R [Centre for Toxicology, Department of Environmental Biology, University of Guelph, Guelph, Ontario, N1G 2W1 (Canada)

2005-12-15

The impact of a mixture of oxytetracycline, chlortetracycline, tetracycline and doxycycline on Myriophyllum sibiricum and Lemna gibba was investigated using fifteen 12,000-L microcosms (k = 5, n = 3). Significant concentration-response relationships were only found for M. sibiricum, where dry mass was 69, 47, 30, and 7% of controls at respective treatment concentrations of 0.080, 0.218, 0.668, and 2.289 {mu}mol/L. Somatic endpoints were strongly and negatively correlated with percent light transmission, except plant length, which was positively correlated. Treated microcosms experienced a reduction in the percent of surface irradiance penetrating the water column as high as 99.8% at a depth of 70 cm, relative to controls. Position relative to the water column was likely responsible for the differential effects observed between floating (L. gibba) and submerged (M. sibiricum) species of macrophytes. A hazard quotient assessment of the lowest EC{sub 10} value indicated significant risk, exceeding the critical HQ value, but not the lowest EC{sub 25} value. - Mixtures of tetracycline antibiotics pose a risk to submerged but not floating aquatic plants.

Effects of a mixture of tetracyclines to Lemna gibba and Myriophyllum sibiricum evaluated in aquatic microcosms

International Nuclear Information System (INIS)

Brain, Richard A.; Wilson, Christian J.; Johnson, David J.; Sanderson, Hans; Bestari, Ketut; Hanson, Mark L.; Sibley, Paul K.; Solomon, Keith R.

2005-01-01

The impact of a mixture of oxytetracycline, chlortetracycline, tetracycline and doxycycline on Myriophyllum sibiricum and Lemna gibba was investigated using fifteen 12,000-L microcosms (k = 5, n = 3). Significant concentration-response relationships were only found for M. sibiricum, where dry mass was 69, 47, 30, and 7% of controls at respective treatment concentrations of 0.080, 0.218, 0.668, and 2.289 μmol/L. Somatic endpoints were strongly and negatively correlated with percent light transmission, except plant length, which was positively correlated. Treated microcosms experienced a reduction in the percent of surface irradiance penetrating the water column as high as 99.8% at a depth of 70 cm, relative to controls. Position relative to the water column was likely responsible for the differential effects observed between floating (L. gibba) and submerged (M. sibiricum) species of macrophytes. A hazard quotient assessment of the lowest EC 10 value indicated significant risk, exceeding the critical HQ value, but not the lowest EC 25 value. - Mixtures of tetracycline antibiotics pose a risk to submerged but not floating aquatic plants

EFECTOS DEL MERCURIO SOBRE ALGUNAS PLANTAS ACUÁTICAS TROPICALES

Directory of Open Access Journals (Sweden)

Martha Isabel Posada

Full Text Available El presente artículo es una descripción de los efectos del mercurio sobre algunas plantas acuáticas tropicales y sobre los ecosistemas donde habitan. Adicionalmente, se recomienda un protocolo para realizar pruebas de toxicidad con la lenteja de agua (Lemna minor y se presentan los resultados de los preensayos con diferentes concentraciones de sales de mercurio en condiciones de laboratorio. Se encontró que la biodisponibilidad del mercurio depende de factores que facilitan la disolución del elemento en el agua. Algunas plantas actúan como bioindicadores de la presencia de este metal en el medio al retenerlo selectivamente; mientras que otras se comportan como bioacumuladoras al tolerar su presencia y acumularlo en su estructura, y pueden dar paso a la bioconcentración a través de la cadena trófica. De acuerdo con los preensayos de toxicidad realizados con Lemna minor se sugiere que las concentraciones de sal de mercurio adecuadas para la realización de pruebas de toxicidad deben estar entre 0,01 mg/L y 10,0 mg/L.

Preliminary Ecotoxicity and Biodegradability Assessment of Metalworking Fluids

Science.gov (United States)

Gerulová, Kristína; Amcha, Peter; Filická, Slávka

2010-01-01

The main aim of this study was to evaluate the potential of activated sludge from sewage treatment plant to degrade selected MWFs (ecotoxicity to bacterial consortium) and to evaluate the ecotoxicity by Lemna minor-higher plant. After evaluating the ecotoxicity, biodegradations rate with activated sludge was assessed on the basis of COD measurement. Preliminary study of measuring the ecotoxicity according to OECD 221 by Lemna minor shows effective concentration of Emulzin H at the rate of 81.6 mg l-1, for Ecocool 82.9 mg l-1, for BC 25 about 99.3 mg l-1, and for Dasnobor about 97.3 mg l-1. Preliminary study of measuring the ecotoxicity by bacterial consortium according to OECD 209 (STN EN ISO 8192) shows effective concentration of Blasocut BC 25 at the rate 227.4 mg l-1. According to OECD 302B, the biodegradations level of Emulzin H, Ecocool and BC 25 achieved 80% in 10 days. It can be stated that these MWFs have potential to ultimate degradation, but the statement has to be confirmed by a biodegradability test with other parameters than COD, which exhibits some disadvantages in testing O/W emulsions.

What is a good death? Minority and non-minority perspectives.

Science.gov (United States)

Tong, Elizabeth; McGraw, Sarah A; Dobihal, Edward; Baggish, Rosemary; Cherlin, Emily; Bradley, Elizabeth H

2003-01-01

While much attention has been directed at improving the quality of care at the end of life, few studies have examined what determines a good death in different individuals. We sought to identify common domains that characterize a good death in a diverse range of community-dwelling individuals, and to describe differences that might exist between minority and non-minority community-dwelling individuals' views. Using data from 13 focus groups, we identified 10 domains that characterize the quality of the death experience: 1) physical comfort, 2) burdens on family, 3) location and environment, 4) presence of others, 5) concerns regarding prolongation of life, 6) communication, 7) completion and emotional health, 8) spiritual care, 9) cultural concerns, 10) individualization. Differences in minority compared to non-minority views were apparent within the domains of spiritual concerns, cultural concerns, and individualization. The findings may help in efforts to encourage more culturally sensitive and humane end-of-life care for both minority and non-minority individuals.

Development of Scanning Ultrafast Electron Microscope Capability.

Energy Technology Data Exchange (ETDEWEB)

Collins, Kimberlee Chiyoko [Sandia National Lab. (SNL-CA), Livermore, CA (United States); Talin, Albert Alec [Sandia National Lab. (SNL-CA), Livermore, CA (United States); Chandler, David W. [Sandia National Lab. (SNL-CA), Livermore, CA (United States); Michael, Joseph R. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

2016-11-01

Modern semiconductor devices rely on the transport of minority charge carriers. Direct examination of minority carrier lifetimes in real devices with nanometer-scale features requires a measurement method with simultaneously high spatial and temporal resolutions. Achieving nanometer spatial resolutions at sub-nanosecond temporal resolution is possible with pump-probe methods that utilize electrons as probes. Recently, a stroboscopic scanning electron microscope was developed at Caltech, and used to study carrier transport across a Si p-n junction [ 1 , 2 , 3 ] . In this report, we detail our development of a prototype scanning ultrafast electron microscope system at Sandia National Laboratories based on the original Caltech design. This effort represents Sandia's first exploration into ultrafast electron microscopy.

Effects of coronatine elicitation on growth and metabolic profiles of Lemna paucicostata culture.

Directory of Open Access Journals (Sweden)

Jin-Young Kim

Full Text Available In this study, the effects of coronatine treatment on the growth, comprehensive metabolic profiles, and productivity of bioactive compounds, including phenolics and phytosterols, in whole plant cultures of Lemna paucicostata were investigated using gas chromatography-mass spectrometry (GC-MS coupled with multivariate statistical analysis. To determine the optimal timing of coronatine elicitation, coronatine was added on days 0, 23, and 28 after inoculation. The total growth of L. paucicostata was not significantly different between the coronatine treated groups and the control. The coronatine treatment in L. paucicostata induced increases in the content of hydroxycinnamic acids, such as caffeic acid, isoferulic acid, ρ-coumaric acid, sinapic acid, and phytosterols, such as campesterol and β-sitosterol. The productivity of these useful metabolites was highest when coronatine was added on day 0 and harvested on day 32. These results suggest that coronatine treatment on day 0 activates the phenolic and phytosterol biosynthetic pathways in L. paucicostata to a greater extent than in the control. To the best of our knowledge, this is the first report to investigate the effects of coronatine on the alteration of metabolism in L. paucicostata based on GC-MS profiling. The results of this research provide a foundation for designing strategies for enhanced production of useful metabolites for pharmaceutical and nutraceutical industries by cultivation of L. paucicostata.

Nuclear microscopy as a tool in TiO{sub 2} nanoparticles bioaccumulation studies in aquatic species

Energy Technology Data Exchange (ETDEWEB)

Pinheiro, Teresa, E-mail: murmur@itn.pt [IST/ITN, Instituto Superior Técnico, Universidade Técnica de Lisboa and Centro de Física Nuclear, Universidade de Lisboa (Portugal); Moita, Liliana; Silva, Luís; Mendonça, Elsa; Picado, Ana [LNEG, Laboratório Nacional de Energia e Geologia, I.P. Estrada do Paço do Lumiar 22, 1649-038 Lisboa (Portugal)

2013-07-01

Engineered Titanium nanoparticles are used for a wide range of applications from coatings, sunscreen cosmetic additives to solar cells or water treatment agents. Inevitably environmental exposure can be expected and data on the ecotoxicological evaluation of nanoparticles are still scarce. The potential effects of nanoparticles of titanium dioxide (TiO{sub 2}) on two model organisms, the water flea, Daphnia magna and the duckweed Lemna minor, were examined in semichronic toxicity tests. Daphnia and Lemna were exposed to TiO{sub 2} nanoparticles (average particle size value of 28 ± 11 nm (n = 42); concentration range, 1.4–25 mg/L) by dietary route and growth in medium containing the nanoparticles of TiO{sub 2}, respectively. Both morphology and microdistribution of Ti in the individuals were examined by nuclear microscopy techniques. A significant amount of TiO{sub 2} was found accumulated in Daphnia exposed to nanoparticles. Nuclear microscopy imaging revealed that Ti was localized only in the digestive tract of the Daphnia, which displayed difficulty in eliminating the nanoparticles from their body. Daphnia showed higher mortality when exposed to higher concentrations of TiO{sub 2} (>10 mg/L). The exposure to TiO{sub 2} nanoparticles above 25 mg/L caused morphological alterations in Lemna. The roots became stiff and fronds colorless. The Ti mapping of cross-sections of roots and fronds showed that Ti was mainly deposited in the epidermis of the fronds and roots, with minor internalization. In summary, exposure of aquatic organisms to TiO{sub 2} nanoparticles may alter the physiology of these organisms at individual and population levels, posing risks to aquatic ecosystems.

Nuclear microscopy as a tool in TiO2 nanoparticles bioaccumulation studies in aquatic species

Science.gov (United States)

Pinheiro, Teresa; Moita, Liliana; Silva, Luís; Mendonça, Elsa; Picado, Ana

2013-07-01

Engineered Titanium nanoparticles are used for a wide range of applications from coatings, sunscreen cosmetic additives to solar cells or water treatment agents. Inevitably environmental exposure can be expected and data on the ecotoxicological evaluation of nanoparticles are still scarce. The potential effects of nanoparticles of titanium dioxide (TiO2) on two model organisms, the water flea, Daphnia magna and the duckweed Lemna minor, were examined in semichronic toxicity tests. Daphnia and Lemna were exposed to TiO2 nanoparticles (average particle size value of 28 ± 11 nm (n = 42); concentration range, 1.4-25 mg/L) by dietary route and growth in medium containing the nanoparticles of TiO2, respectively. Both morphology and microdistribution of Ti in the individuals were examined by nuclear microscopy techniques. A significant amount of TiO2 was found accumulated in Daphnia exposed to nanoparticles. Nuclear microscopy imaging revealed that Ti was localized only in the digestive tract of the Daphnia, which displayed difficulty in eliminating the nanoparticles from their body. Daphnia showed higher mortality when exposed to higher concentrations of TiO2 (>10 mg/L). The exposure to TiO2 nanoparticles above 25 mg/L caused morphological alterations in Lemna. The roots became stiff and fronds colorless. The Ti mapping of cross-sections of roots and fronds showed that Ti was mainly deposited in the epidermis of the fronds and roots, with minor internalization. In summary, exposure of aquatic organisms to TiO2 nanoparticles may alter the physiology of these organisms at individual and population levels, posing risks to aquatic ecosystems.

Nuclear microscopy as a tool in TiO2 nanoparticles bioaccumulation studies in aquatic species

International Nuclear Information System (INIS)

Pinheiro, Teresa; Moita, Liliana; Silva, Luís; Mendonça, Elsa; Picado, Ana

2013-01-01

Engineered Titanium nanoparticles are used for a wide range of applications from coatings, sunscreen cosmetic additives to solar cells or water treatment agents. Inevitably environmental exposure can be expected and data on the ecotoxicological evaluation of nanoparticles are still scarce. The potential effects of nanoparticles of titanium dioxide (TiO 2 ) on two model organisms, the water flea, Daphnia magna and the duckweed Lemna minor, were examined in semichronic toxicity tests. Daphnia and Lemna were exposed to TiO 2 nanoparticles (average particle size value of 28 ± 11 nm (n = 42); concentration range, 1.4–25 mg/L) by dietary route and growth in medium containing the nanoparticles of TiO 2 , respectively. Both morphology and microdistribution of Ti in the individuals were examined by nuclear microscopy techniques. A significant amount of TiO 2 was found accumulated in Daphnia exposed to nanoparticles. Nuclear microscopy imaging revealed that Ti was localized only in the digestive tract of the Daphnia, which displayed difficulty in eliminating the nanoparticles from their body. Daphnia showed higher mortality when exposed to higher concentrations of TiO 2 (>10 mg/L). The exposure to TiO 2 nanoparticles above 25 mg/L caused morphological alterations in Lemna. The roots became stiff and fronds colorless. The Ti mapping of cross-sections of roots and fronds showed that Ti was mainly deposited in the epidermis of the fronds and roots, with minor internalization. In summary, exposure of aquatic organisms to TiO 2 nanoparticles may alter the physiology of these organisms at individual and population levels, posing risks to aquatic ecosystems

Minorities and majorities

NARCIS (Netherlands)

Nijman, J.E.; Fassbender, B.; Peters, A.

2012-01-01

This chapter discusses the paradox of minorities as a constitutive Other of international law. While minorities have been viewed as outside the international legal system for centuries, minorities have at the same time made a significant and fundamental contribution to precisely that system, as they

Competition between Free-Floating Plants Is Strongly Driven by Previously Experienced Phosphorus Concentrations in the Water Column.

Directory of Open Access Journals (Sweden)

Edwin T H M Peeters

Full Text Available Nutrients can determine the outcome of the competition between different floating plant species. The response of floating plants to current phosphorus levels may be affected by previously experienced phosphorus concentrations because some species have the ability to store excess phosphorus for later use. This might have an impact on their competition. Here, we investigate the effect of previous and actual phosphorus concentrations on the growth rate of free-floating plant species (Azolla filiculoides, Lemna minor/gibba and Ricciocarpus natansand the effect of phosphorus history on the competition between L. minor/gibba and A. filiculoides and between L. minor/gibba and R. natans. As expected, plant growth was lower when previously kept at low instead of high phosphorus concentrations. Growth of L. minor/gibba and A. filiculoides with a phosphorus rich history was comparable for low and high actual phosphorus concentrations, however, internal phosphorus concentrations were significantly lower with low actual phosphorus concentration. This indicates that both species perform luxury phosphorus uptake. Furthermore, internal P concentration in Azolla and Lemna increased within two weeks after a period of P deficit without a strong increase in growth. A. filiculoides in a mixture with L. minor/gibba grew faster than its monoculture. Morphological differences may explain why A. filiculoides outcompeted L. minor/gibba and these differences may be induced by phosphorus concentrations in the past. Growth of L. minor/gibba was only reduced by the presence of A. filiculoides with a high phosphorus history. Growth of L. minor/gibba and R. natans in mixtures was positively affected only when they had a high phosphorus history themselves and their competitor a low phosphorus history. These observations clearly indicate that phosphorus history of competing plants is important for understanding the outcome of the competition. Therefore, actual and previously

Competition between Free-Floating Plants Is Strongly Driven by Previously Experienced Phosphorus Concentrations in the Water Column

Science.gov (United States)

Peeters, Edwin T. H. M.; Neefjes, Rozemarijn E. M.; van Zuidam, Bastiaan G.

2016-01-01

Nutrients can determine the outcome of the competition between different floating plant species. The response of floating plants to current phosphorus levels may be affected by previously experienced phosphorus concentrations because some species have the ability to store excess phosphorus for later use. This might have an impact on their competition. Here, we investigate the effect of previous and actual phosphorus concentrations on the growth rate of free-floating plant species (Azolla filiculoides, Lemna minor/gibba and Ricciocarpus natans)and the effect of phosphorus history on the competition between L. minor/gibba and A. filiculoides and between L. minor/gibba and R. natans. As expected, plant growth was lower when previously kept at low instead of high phosphorus concentrations. Growth of L. minor/gibba and A. filiculoides with a phosphorus rich history was comparable for low and high actual phosphorus concentrations, however, internal phosphorus concentrations were significantly lower with low actual phosphorus concentration. This indicates that both species perform luxury phosphorus uptake. Furthermore, internal P concentration in Azolla and Lemna increased within two weeks after a period of P deficit without a strong increase in growth. A. filiculoides in a mixture with L. minor/gibba grew faster than its monoculture. Morphological differences may explain why A. filiculoides outcompeted L. minor/gibba and these differences may be induced by phosphorus concentrations in the past. Growth of L. minor/gibba was only reduced by the presence of A. filiculoides with a high phosphorus history. Growth of L. minor/gibba and R. natans in mixtures was positively affected only when they had a high phosphorus history themselves and their competitor a low phosphorus history. These observations clearly indicate that phosphorus history of competing plants is important for understanding the outcome of the competition. Therefore, actual and previously experienced phosphorus

Power Electronics

DEFF Research Database (Denmark)

Iov, Florin; Ciobotaru, Mihai; Blaabjerg, Frede

2008-01-01

is to change the electrical power production sources from the conventional, fossil (and short term) based energy sources to renewable energy resources. The other is to use high efficient power electronics in power generation, power transmission/distribution and end-user application. This paper discuss the most...... emerging renewable energy sources, wind energy, which by means of power electronics are changing from being a minor energy source to be acting as an important power source in the energy system. Power electronics is the enabling technology and the presentation will cover the development in wind turbine...... technology from kW to MW, discuss which power electronic solutions are most feasible and used today....

浮萍(Lemna aequinoctialis)干粉对Pb2+的吸附%Biosorption of Pb2+ by Dried Powder of Duckweed (Lemna aequinoctialis)

Institute of Scientific and Technical Information of China (English)

陈兰钗; 方扬; 靳艳玲; 陈谦; 赵永贵; 肖瑶; 赵海

2013-01-01

为开发高效去除重金属铅(Pb2+)污染的生物吸附剂,以浮萍(Lemna aequinoctialis)干粉为吸附剂原料,通过单因素实验研究了该吸附剂吸附Pb2+的主要影响因素;利用吸附动力学方程和等温吸附方程对实验数据进行拟合;并采用红外光谱分析仪研究了吸附前后吸附剂表面的化学基团变化.结果表明,对吸附效果影响显著的因素有溶液初始pH值、吸附剂颗粒大小和Pb2+初始浓度;参与吸附pb2+的基团可能是吸附剂所含糖类中的羟基及酰胺中的氨基;其吸附行为符合准二级动力学方程,相关系数R2为0.999 95,k2为3.65 g min-1mg-1;等温吸附曲线符合Freundlich方程,浮萍对Pb2+的吸附量在高达56.79 mg/g时仍未达到吸附饱和点.本研究表明L.aequinoctialis干粉作为一种新型生物吸附剂,对Pb2+的吸附条件要求不严格,吸附速率快,吸附容量大,在较宽的条件范围内都可达到较高的去除率.图5表2参31

Effect of zinc ions on nutrient removal and growth of Lemna aequinoctialis from anaerobically digested swine wastewater.

Science.gov (United States)

Zhou, Qi; Lin, Yan; Li, Xiang; Yang, Chunping; Han, Zhenfeng; Zeng, Guangming; Lu, Li; He, Shanying

2018-02-01

The effect of Zn 2+ on ammonium and phosphorous removal and duckweed growth was evaluated for treatment of anaerobically digested swine wastewater (ADSW) at various initial Zn 2+ concentrations ranging from 1.0 to 15mg/L. Lemna aequinoctialis taken from a local pond was selected for the treatment, and its fresh weight and contents of proteins, photosynthetic pigments, and vitamin E were examined. Results showed that the optimal Zn 2+ concentration was 5.0mg/L for NH 3 -N and TP removal, the duckweed growth, and the accumulation of proteins in the duckweed. A maximum content of photosynthetic pigments increased with the increase of initial Zn 2+ concentration, and it arrived earlier for a higher concentration of Zn 2+ . Vitamin E content in the duckweed reached 4.5mg/kg at 15mg/L Zn 2+ in 12-day cultivation, which showed the potential for producing and harvesting a high value-added product of vitamin E by culturing duckweed in ADSW. Copyright © 2017 Elsevier Ltd. All rights reserved.

Accessing medication information by ethnic minorities: barriers and possible solutions.

Science.gov (United States)

Schaafsma, Evelyn S; Raynor, Theo D; de Jong-van den Berg, Lolkje T

2003-10-01

This review discusses two main questions: how suitable is current consumer medication information for minority ethnic groups, and what are effective strategies to overcome existing barriers. The focus is on minority groups whose first language is not the language of the healthcare system. We searched electronic databases and printed scientific journals focusing on (ethnic) minorities, health and/or (intercultural) communication. We also asked a discussion group for references. We found only a few articles on intercultural communication on medication or pharmacy information and one article on the improvement of intercultural communication in the pharmacy. Barriers to the access of medication information by ethnic minorities include second language issues and cultural differences due to different health beliefs, together with the low socio-economic status often seen among ethnic minorities. Cultural differences also exist among different socio-economic classes rather than only among ethnic groups. Most often, informal interpreters are used to improve intercultural communication. However, this may result in miscommunication due to a lack of medical knowledge or training on the part of the interpreter. To minimise miscommunication, bilingual health professionals or health interpreters/advocates can be used, although communication problems may still occur. The effectiveness of written information depends on the literacy skills of the target population. Cultural, medical and dialect biases should be avoided by testing the material. Multimedia systems may be alternatives to conventional written information. Barriers that ethnic minorities face in accessing medication information and possible solutions involving counselling and additional tools were identified for pharmacy practice. However, more research is needed to develop effective strategies for patient counselling in pharmacy to meet the needs of ethnic minorities.

Do Double Minority Students Face Double Jeopardy? Testing Minority Stress Theory

Science.gov (United States)

Hayes, Jeffrey A.; Chun-Kennedy, Caitlin; Edens, Astrid; Locke, Benjamin D.

2011-01-01

Data from 2 studies revealed that ethnic and sexual minority clients experienced greater psychological distress on multiple dimensions than did European American or heterosexual clients, respectively, as did ethnic and sexual minority students who were not clients. Among sexual minority students, ethnicity was not an added source of distress.…

水杨酸诱导膨胀浮萍（Lemna gibba SH0204）开花%Flower-Induction of Lemna gibba SH0204 by Salicylic Acid

Institute of Scientific and Technical Information of China (English)

黄猛; 许亚良; Kanjana Khaeso; 孙雪飘; 张家明

2015-01-01

用水杨酸(SA)诱导膨胀浮萍开花，结果显示，在液体1/2Hoagland培养基中加入适当浓度的SA对开花有显著促进作用， SA浓度为20μmol·L-1时开花率最高，达到39.37%。SA在诱导开花的同时，明显抑制叶状体的生长，在浓度为80μmol·L-1时，叶状体死亡率达到94.38%。此外，本研究尝试在固体1/2Hoagland培养基上诱导膨胀浮萍开花，结果表明，固体培养基比液体培养基更有利于诱导开花， SA浓度为20μmol·L-1时，开花率超过45%，死亡率显著降低。在固体培养基上，方便对开花植株进行跟踪和操作，因此，用固体培养基诱导开花比液体培养基更有应用价值。光学和电子显微镜的观察结果显示，花粉粒呈近圆球形，表面有网状带刺纹饰。%Salicylic acid (SA) was used in the lfower induction of the duckweed Lemna gibba SH0204. Flowers were induced efifciently by suitable concentrations of SA in the liquid 1/2Hoagland medium, and the highest induction rate reached 39.37%at 20μmol·L-1 SA. In the meantime, SA inhibited the growth of L. gibba, and the frond mortality reached 94.38%at 80μmol·L-1 SA. Solid medium was used in the lfower induction of duck-weeds, and was found to be more optimal compared to liquid medium. The highest flower induction rate reached 45%on the solid medium, and the frond mortality decreased signiifcantly. Moreover, the fronds were kept in the original locations on the solid medium, avoiding the damage of the lfowers on the liquid medium by moving around, and providing convenience of tracing or operation with the lfowers. Therefore, solid medium is a practically more useful medium in lfower induction of duckweeds. Electron and light microscopic observation revealed that the pollen grains were spheroid and small, with echinate-reticulate exine.

Fission cross section measurements for minor actinides

Energy Technology Data Exchange (ETDEWEB)

Fursov, B. [IPPE, Obninsk (Russian Federation)

1997-03-01

The main task of this work is the measurement of fast neutron induced fission cross section for minor actinides of {sup 238}Pu, {sup 242m}Am, {sup 243,244,245,246,247,248}Cm. The task of the work is to increase the accuracy of data in MeV energy region. Basic experimental method, fissile samples, fission detectors and electronics, track detectors, alpha counting, neutron generation, fission rate measurement, corrections to the data and error analysis are presented in this paper. (author)

Vaccines for minor use and minor species (MUMS)--industry's views.

Science.gov (United States)

Bönisch, B

2004-01-01

Over the past 30 years the importance of vaccines for minor use and minor species has changed for multinational animal health companies. The major reasons for this are being reviewed, with a particular focus on technical, financial and business aspects. Key regulatory obstacles to the development of new products for minor uses and minor species are identified, and examples of vaccines falling into the various categories are provided. A number of proposals are offered with the intention of resolving the medicines availability problem between all the stakeholders involved. Finally, based on the presented scientific and regulatory considerations, ideas are shared as to where the legal and economical framework would need to change to reach a viable solution.

d-3He reaction measurements during fast wave minority heating in PLT

International Nuclear Information System (INIS)

Chrien, R.E.; Strachan, J.D.

1983-01-01

Time- and energy-resolved d- 3 He fusion reactions have been measured to infer the energy of the d + or He ++ minority ions heated near their cyclotron frequency by the magnetosonic fast wave. The average energy of the reacting 3 He ions during 3 He minority heating is in the range of 100 to 400 keV, as deduced from the magnitude of the reaction rate, its decay time, and the energy spread of the proton reaction products. The observed reaction rate and its scaling with wave power and electron density and temperature are in qualitative agreement with a radial reaction rate model using the minority distribution predicted from quasilinear velocity space diffusion. Oscillations in the reaction rate are observed concurrent with sawtooth and m = 2 MHD activity in the plasma

Toxicity of the fluoroquinolone antibiotics enrofloxacin and ciprofloxacin to photoautotrophic aquatic organisms.

Science.gov (United States)

Ebert, Ina; Bachmann, Jean; Kühnen, Ute; Küster, Anette; Kussatz, Carola; Maletzki, Dirk; Schlüter, Christoph

2011-12-01

The present study investigated the growth inhibition effect of the fluoroquinolone antibiotics enrofloxacin and ciprofloxacin on four photoautotrophic aquatic species: the freshwater microalga Desmodesmus subspicatus, the cyanobacterium Anabaena flos-aquae, the monocotyledonous macrophyte Lemna minor, and the dicotyledonous macrophyte Myriophyllum spicatum. Both antibiotics, which act by inhibiting the bacterial DNA gyrase, demonstrated high toxicity to A. flos-aquae and L. minor and moderate to slight toxicity to D. subspicatus and M. spicatum. The cyanobacterium was the most sensitive species with median effective concentration (EC50) values of 173 and 10.2 µg/L for enrofloxacin and ciprofloxacin, respectively. Lemna minor proved to be similarly sensitive, with EC50 values of 107 and 62.5 µg/L for enrofloxacin and ciprofloxacin, respectively. While enrofloxacin was more toxic to green algae, ciprofloxacin was more toxic to cyanobacteria. Calculated EC50s for D. subspicatus were 5,568 µg/L and >8,042 µg/L for enrofloxacin and ciprofloxacin, respectively. These data, as well as effect data from the literature, were compared with predicted and reported environmental concentrations. For two of the four species, a risk was identified at ciprofloxacin concentrations found in surface waters, sewage treatment plant influents and effluents, as well as in hospital effluents. For ciprofloxacin the results of the present study indicate a risk even at the predicted environmental concentration. In contrast, for enrofloxacin no risk was identified at predicted and measured concentrations. Copyright © 2011 SETAC.

Minority engineering scholarships, 2012.

Science.gov (United States)

2014-02-01

Scholarships for Minority Students Studying Engineering and Science: Support will make scholarships available to minority students : interested in engineering and science and will increase significantly the number of minority students that Missouri S...

Physician Knowledge and Attitudes around Confidential Care for Minor Patients.

Science.gov (United States)

Riley, Margaret; Ahmed, Sana; Reed, Barbara D; Quint, Elisabeth H

2015-08-01

Minor adolescent patients have a legal right to access certain medical services confidentially without parental consent or notification. We sought to assess physicians' knowledge of these laws, attitudes around the provision of confidential care to minors, and barriers to providing confidential care. An anonymous online survey was sent to physicians in the Departments of Family Medicine, Internal Medicine-Pediatrics, Obstetrics/Gynecology, and Pediatrics at the University of Michigan. Response rate was 40% (259/650). The majority of physicians felt comfortable addressing sexual health, mental health, and substance use with adolescent patients. On average, physicians answered just over half of the legal knowledge questions correctly (mean 56.6% ± 16.7%). The majority of physicians approved of laws allowing minors to consent for confidential care (90.8% ± 1.7% approval), while substantially fewer (45.1% ± 4.5%) approved of laws allowing parental notification of this care at the physician's discretion. Most physicians agreed that assured access to confidential care should be a right for adolescents. After taking the survey most physicians (76.6%) felt they needed additional training on confidentiality laws. The provision of confidential care to minors was perceived to be most inhibited by insurance issues, parental concerns/relationships with the family, and issues with the electronic medical record. Physicians are comfortable discussing sensitive issues with adolescents and generally approve of minor consent laws, but lack knowledge about what services a minor can access confidentially. Further research is needed to assess best methods to educate physicians about minors' legal rights to confidential healthcare services. Copyright © 2015 North American Society for Pediatric and Adolescent Gynecology. Published by Elsevier Inc. All rights reserved.

Integrated Evaluation and Indication of Water Quality by Lemna paucicostata%稀脉萍(Lemna paucicostata)对水质的综合评价和指示作用

Institute of Scientific and Technical Information of China (English)

李天煜

2008-01-01

为探讨利用我国本土植物进行水质综合评价和指示的可行性,试验研究了我国特有的浮萍属植物--稀脉萍(Lemna paucicostata)对不同来源水(自来水、雨水为唯一来源的池塘水、接纳多种排放废水的湖水及垃圾填埋场渗滤液)水质的综合评价和指示效果.结果表明,1)就不同来源水而言,随着水质的下降(自来水、池塘水、湖水、渗滤液),稀脉萍叶状体和群体7d相对增殖率(相对于对照)均逐渐降低;2)就某一污水而言,随着水质的下降(渗滤液稀释4096-128倍),稀脉萍叶状体7d相对增殖率逐渐降低,而群体相对增殖率没有明显变化规律.以上结果提示.稀脉萍对水质具有一定的评价和指示作用,其叶状体相对增殖率可应用于水质的生物学监测和综合评价.

Phytoremediation of anatoxin-a by aquatic macrophyte Lemna trisulca L.

Science.gov (United States)

Kaminski, Ariel; Bober, Beata; Chrapusta, Ewelina; Bialczyk, Jan

2014-10-01

The neurotoxin anatoxin-a (ANTX-a), one of the most common cyanotoxin, poses a health risk to people and can be lethal to aquatic organisms. This paper presents results on its bioremediation by the aquatic macrophyte Lemna trisulca. We show that the plant is resistant to the harmful impact of toxin and is capable of removing ANTX-a from water. Some of the ANTX-a concentrations which were used in our experiments were much higher than those found in natural conditions. The exposition of L. trisulca to 2.5 μg ANTX-a/mL did not affect its biomass accumulation within 24 d. Significant decreases in biomass content by 21% and 30% were demonstrated in samples cultivated in media containing 12.5 μg ANTX-a/mL after 18 and 24 day of experiment, respectively. One gram of fresh weight (f.w.) of L. trisulca cultured for 14 d in the media containing 50 μg ANTX-a removed 95% of the initial toxin concentration; for media with 250 μg ANTX-a, 86% was removed. In tests of ANTX-a binding stability and degradation we transferred the macrophyte to fresh media without added toxin; within 14 d the content of accumulated ANTX-a in the macrophyte decreased by 76% (from initial 19.3 μg ANTX-a/gf.w.), 71% (from 37.3 μg ANTX-a/g f.w.) and 47% (from 63.7 μg ANTX-a/g f.w.). The quantity of ANTX-a released to media was minimal: from 3.5% to 5.1% of the initial bioaccumulated value. The data show that part of the ANTX-a was degraded. Mass spectra analyses did not indicate transformation of ANTX-a to already known forms. These findings suggest that L. trisulca has much potential as a phytoremediation agent for stabilization of aquatic environments. Copyright © 2014 Elsevier Ltd. All rights reserved.

Use of various acute, sublethal and early life-stage tests to evaluate the toxicity of refinery effluents

International Nuclear Information System (INIS)

Sherry, J.; Scott, B.; Dutka, B.

1997-01-01

The toxicities of effluents from three Ontario, Canada, refineries were assessed with microbes, plants, invertebrates, and fish. Acute toxicity was assessed by the Microtox test, an assay based on electron transport activity in submitochondrial particles, and Daphnia magna (water flea); growth of Selenastrum capricornutum (alga); growth of Lemna minor (aquatic plant); germination of Lactuca sativa (nonaquatic plant); survival, growth, and maturation of Panagrellus redivivus (nematode); and genotoxicity in the SOS-Chromotest. Only the Microtox test and the submitochondrial particle test detected acute toxicity in the effluent samples. Reduced survival and sublethal responses were caused by some effluents, but not all effluents were toxic, and none caused a response in all of the tests applied. The results suggest that the effluent treatment systems used at Ontario refineries have largely eliminated acute toxicity to the organisms in their test battery. Although reduced survival and sublethal effects were detected in some of the effluents, the effects were minor. Some of the tests provided evidence, albeit weak, of variations in the responses of the test organisms to a temporal series of effluent samples. Not unexpectedly, there were also minor differences in the responses of the tests to effluents from the three refineries. The fathead minnow test seems to be a sensitive indicator of the sublethal toxicity of Ontario refinery effluents

Single-electron tunneling in InP nanowires

NARCIS (Netherlands)

Franceschi, De S.; Dam, Van J.A.; Bakkers, E.P.A.M.; Feiner, L.F.; Gurevich, L.; Kouwenhoven, L.P.

2003-01-01

A study was performed on single-electron tunneling in InP nanowires. The contact resistances as low as ~10 k¿, with minor temperature dependence were obtained. The Coulomb-blockade behavior was shown with single-electron charging energies of ~1 meV.

Minority-carrier injection-enhanced annealing of radiation damage to InGaP solar cells

International Nuclear Information System (INIS)

Yamaguchi, M.; Okuda, T.; Taylor, S.J.

1997-01-01

The observation of minority-carrier injection-enhanced annealing of radiation-induced defects in InGaP is reported. 1-MeV electron irradiation results demonstrate superior radiation-resistance of InGa 0.5 P 0.5 solar cells compared to GaAs-on-Ge cells. Moreover, minority-carrier injection under forward bias conditions is shown to enhance defect annealing in InGaP and to result in the recovery of InGaP solar cell properties. These results suggest that the radiation-resistance of InGaP-based devices such as InGaP/GaAs(/Ge) multijunction solar cells and InGaP(As) light-emitting devices is further improved under minority-carrier injection condition. copyright 1997 American Institute of Physics

First record of Molorchus minor minor (Linnaeus (Coleoptera, Cerambycidae in Brazil

Directory of Open Access Journals (Sweden)

Ubirajara R. Martins

2015-03-01

Full Text Available Molorchus minor minor (Linnaeus (Coleoptera, Cerambycidae is recorded for the first time in Brazil (Bahia. It was originally described from Europe and is currently widely distributed in that continent and Asia.

The Trojan minor planets

Science.gov (United States)

Spratt, Christopher E.

1988-08-01

There are (March, 1988) 3774 minor planets which have received a permanent number. Of these, there are some whose mean distance to the sun is very nearly equal to that of Jupiter, and whose heliocentric longitudes from that planet are about 60°, so that the three bodies concerned (sun, Jupiter, minor planet) make an approximate equilateral triangle. These minor planets, which occur in two distinct groups, one preceding Jupiter and one following, have received the names of the heroes of the Trojan war. This paper concerns the 49 numbered minor planets of this group.

Minorities in Iran

DEFF Research Database (Denmark)

Elling, Rasmus Christian

Contrary to the popular understanding of Iran as a Persian nation, half of the country's population consists of minorities, among whom there has been significant ethnic mobilization at crucial stages in Iranian history. One such stage is now: suppressed minority demands, identity claims, and deba......Contrary to the popular understanding of Iran as a Persian nation, half of the country's population consists of minorities, among whom there has been significant ethnic mobilization at crucial stages in Iranian history. One such stage is now: suppressed minority demands, identity claims......, and debates on diversity have entered public discourse and politics. In 2005–2007, Iran was rocked by the most widespread ethnic unrest experienced in that country since the revolution. The same period was also marked by the re-emergence of nationalism. This interdisciplinary book takes a long-overdue step...

Avaliação de lagoas de Lemnas (Landoltia punctata) para o polimento de esgoto sanitário e fixação de gás carbônico

OpenAIRE

Brugnago, Natália

2014-01-01

Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro Tecnológico, Programa de Pós-Graduação em Engenharia Ambiental, Florianópolis, 2014. A fim de mitigar o problema da poluição das águas, as lagoas de lemnas têm sido consideradas como uma tecnologia eficiente e de baixo custo, sendo então aplicadas para o tratamento de esgoto sanitário e agroindustrial. A elevada eficiência na remoção de nutrientes (N e P) é uma das principais vantagens dessa tecnologia. Além disso, a b...

Future goal setting, task motivation and learning of minority and non-minority students in Dutch schools.

Science.gov (United States)

Andriessen, Iris; Phalet, Karen; Lens, Willy

2006-12-01

Cross-cultural research on minority school achievement yields mixed findings on the motivational impact of future goal setting for students from disadvantaged minority groups. Relevant and recent motivational research, integrating Future Time Perspective Theory with Self-Determination Theory, has not yet been validated among minority students. To replicate across cultures the known motivational benefits of perceived instrumentality and internal regulation by distant future goals; to clarify when and how the future motivates minority students' educational performance. Participants in this study were 279 minority students (100 of Turkish and 179 of Moroccan origin) and 229 native Dutch students in Dutch secondary schools. Participants rated the importance of future goals, their perceptions of instrumentality, their task motivation and learning strategies. Dependent measures and their functional relations with future goal setting were simultaneously validated across minority and non-minority students, using structural equation modelling in multiple groups. As expected, Positive Perceived Instrumentality for the future increases task motivation and (indirectly) adaptive learning of both minority and non-minority students. But especially internally regulating future goals are strongly related to more task motivation and indirectly to more adaptive learning strategies. Our findings throw new light on the role of future goal setting in minority school careers: distant future goals enhance minority and non-minority students' motivation and learning, if students perceive positive instrumentality and if their schoolwork is internally regulated by future goals.

Deep levels in as-grown and electron-irradiated n-type GaN studied by deep level transient spectroscopy and minority carrier transient spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Duc, Tran Thien [Department of Physics, Chemistry and Biology (IFM), Linköping University, S-581 83 Linköping (Sweden); School of Engineering Physics, Hanoi University of Science and Technology, 1 Dai Co Viet Road, Hanoi (Viet Nam); Pozina, Galia; Son, Nguyen Tien; Kordina, Olof; Janzén, Erik; Hemmingsson, Carl [Department of Physics, Chemistry and Biology (IFM), Linköping University, S-581 83 Linköping (Sweden); Ohshima, Takeshi [Japan Atomic Energy Agency (JAEA), Takasaki, Gunma 370-1292 (Japan)

2016-03-07

Development of high performance GaN-based devices is strongly dependent on the possibility to control and understand defects in material. Important information about deep level defects is obtained by deep level transient spectroscopy and minority carrier transient spectroscopy on as-grown and electron irradiated n-type bulk GaN with low threading dislocation density produced by halide vapor phase epitaxy. One hole trap labelled H1 (E{sub V} + 0.34 eV) has been detected on as-grown GaN sample. After 2 MeV electron irradiation, the concentration of H1 increases and at fluences higher than 5 × 10{sup 14 }cm{sup −2}, a second hole trap labelled H2 is observed. Simultaneously, the concentration of two electron traps, labelled T1 (E{sub C} – 0.12 eV) and T2 (E{sub C} – 0.23 eV), increases. By studying the increase of the defect concentration versus electron irradiation fluence, the introduction rate of T1 and T2 using 2 MeV- electrons was determined to be 7 × 10{sup −3 }cm{sup −1} and 0.9 cm{sup −1}, respectively. Due to the low introduction rate of T1, it is suggested that the defect is associated with a complex. The high introduction rate of trap H1 and T2 suggests that the defects are associated with primary intrinsic defects or complexes. Some deep levels previously observed in irradiated GaN layers with higher threading dislocation densities are not detected in present investigation. It is therefore suggested that the absent traps may be related to primary defects segregated around dislocations.

Sexual Minority Stressors, Internalizing Symptoms, and Unhealthy Eating Behaviors in Sexual Minority Youth

Science.gov (United States)

Katz-Wise, Sabra L.; Calzo, Jerel P.; Scherer, Emily A.; Sarda, Vishnudas; Jackson, Benita; Haines, Jess; Austin, S. Bryn

2015-01-01

Background Sexual minorities are more likely than heterosexuals to engage in unhealthy eating behaviors. Purpose To examine sexual minority stressors and internalizing symptoms as predictors of unhealthy eating behaviors among sexual minority youth. Methods We used longitudinal data from 1461 sexual minority youth in the Growing Up Today Study, across ages 14-28 years. We hypothesized that sexual minority stressors would predict unhealthy eating behaviors, in part due to internalizing symptoms. Linear regression models fit via generalized estimating equations were stratified by gender and sexual orientation. Results Significant positive and inverse associations between stressors and eating behaviors were detected among females and males, with more significant associations among females. Associations were attenuated by up to 71% for females and 12% for males when internalizing symptoms were added to the models. Conclusions Sexual minority stressors predicted unhealthy eating behaviors overall and more so for some sexual orientation and gender groups; associations were partially explained by internalizing symptoms. The conceptual model appears to best describe the experiences of bisexual females. Findings have clinical implications for adolescent health. PMID:26156678

From a microcosm to the catchment scale: studying the fate of organic runoff pollutants in aquatic ecosystems

Science.gov (United States)

Böttcher, T.; Schroll, R.

2009-04-01

Spray-drift, drainage, erosion and runoff events are the major causes responsible for deportation of agrochemicals as micropollutants to aquatic non-target sites. These processes can lead to the contamination of nearby freshwater ecosystems with considerably high concentrations of xenobiotics. Thus, it is important to unravel the fate of these pollutants and to evaluate their ecological effects. A novel approach to address this goal was established by the development of a microcosm with multiple sampling abilities enabling quantitative assessment of organic volatilisation, mineralization, metabolization and distribution within the aquatic ecosystem. This microcosm system was designed to support modelling approaches of the catchment scale and gain insights into the fate of pesticides simulating a large scale water body. The potential of this microcosm was exemplified for Isoproturon (IPU), a phenylurea derived systemic herbicide, which is frequently found as contaminant in water samples and with the free-floating macrophyte Lemna minor as non-target species, that is common to occur in rural water bodies. During 21 days exposure time, only a small amount of 14C labeled IPU was removed from the aquatic medium. The major portion (about 5%) was accumulated by Lemna minor resulting in a BCF of 15.8. IPU-volatilisation was very low with 0.13% of the initially applied herbicide. Only a minor amount of IPU was completely metabolized, presumably by rhizosphere microorganisms and released as 14CO2. The novel experimental system allowed to quantitatively investigate the fate of IPU and showed a high reproducibility with a mean average 14C-recovery rate of 97.1

EVOLUTION OF PROGENITORS FOR ELECTRON CAPTURE SUPERNOVAE

International Nuclear Information System (INIS)

Takahashi, Koh; Umeda, Hideyuki; Yoshida, Takashi

2013-01-01

We provide progenitor models for electron capture supernovae (ECSNe) with detailed evolutionary calculation. We include minor electron capture nuclei using a large nuclear reaction network with updated reaction rates. For electron capture, the Coulomb correction of rates is treated and the contribution from neutron-rich isotopes is taken into account in each nuclear statistical equilibrium (NSE) composition. We calculate the evolution of the most massive super asymptotic giant branch stars and show that these stars undergo off-center carbon burning and form ONe cores at the center. These cores become heavier up to the critical mass of 1.367 M ☉ and keep contracting even after the initiation of O+Ne deflagration. Inclusion of minor electron capture nuclei causes convective URCA cooling during the contraction phase, but the effect on the progenitor evolution is small. On the other hand, electron capture by neutron-rich isotopes in the NSE region has a more significant effect. We discuss the uniqueness of the critical core mass for ECSNe and the effect of wind mass loss on the plausibility of our models for ECSN progenitors.

How does electronic cigarette access affect adolescent smoking?

Science.gov (United States)

Friedman, Abigail S

2015-12-01

Understanding electronic cigarettes' effect on tobacco smoking is a central economic and policy issue. This paper examines the causal impact of e-cigarette access on conventional cigarette use by adolescents. Regression analyses consider how state bans on e-cigarette sales to minors influence smoking rates among 12 to 17 year olds. Such bans yield a statistically significant 0.9 percentage point increase in recent smoking in this age group, relative to states without such bans. Results are robust to multiple specifications as well as several falsification and placebo checks. This effect is both consistent with e-cigarette access reducing smoking among minors, and large: banning electronic cigarette sales to minors counteracts 70 percent of the downward pre-trend in teen cigarette smoking for a given two-year period. Copyright © 2015 Elsevier B.V. All rights reserved.

Minority workers or minority human beings? A European dilemma

Science.gov (United States)

Skutnabb-Kangas, Tove; Phillipson, Robert

1996-07-01

"European" identities may be politonymic, toponymic, ethnomyic or linguonymic (Bromley 1984). Each dimension may affect whether migrant minorities are treated as "European", and influence their schooling, integration and rights. Treatment and terminology vary in different states and periods of migration. However, the position for immigrated minorities is that they are still largely seen as workers rather than human beings with equal rights. Lack of success in schools is blamed on the migrants themselves rather than the educational system. This construction of migrants as being deficient is parallel to educational practice which falls within a UN definition of linguistic genocide, and contributes to mis-education. If current efforts in international bodies to codify educational linguistic human rights were to lead to greater support for minorities, this could assist in a redefinition of national identities and a reduction of racism and conflict.

Effect of Aquatic Plants on Phosphorus Removal and Electrical Conductivity Decrease in Municipal Effluent

OpenAIRE

Sara Samimi Loghmani; Ali Abbaspour

2014-01-01

Phosphorus (P) is one of essential elements for living organisms, though its critical concentration in surface and ground waters impose a serious problem such as eutrophication. So treatment of polluted waters is required before discharging to water resources. One of effective ways to decrease water pollution is using aquatic plants. An experiment was conducted in pilots with a closed flowing system on two plants, elodea (egria densa) and duck weed (lemna minor) with four treatments and three...

Minorities and Malnutrition.

Science.gov (United States)

Kornegay, Francis A.

Various aspects of the relationship between minorities and malnutrition are discussed in this brief paper. Malnutrition, one of the byproducts of low economic status, is creating a crisis-proportion health problem affecting minority citizens. Malnutrition seriously affects children, older people in poverty, and chronically unemployed or…

Minority engineering scholarships renewal, 2011.

Science.gov (United States)

2012-08-01

Scholarships for Minority Students Studying Engineering and Science : Support will make scholarships available to minority students : interested in engineering and science and will increase significantly the number of minority students that Missouri ...

A new approach to determine accurately minority-carrier lifetime

International Nuclear Information System (INIS)

Idali Oumhand, M.; Mir, Y.; Zazoui, M.

2009-01-01

Electron or proton irradiations introduce recombination centers, which tend to affect solar cell parameters by reducing the minority-carrier lifetime (MCLT). Because this MCLT plays a fundamental role in the performance degradation of solar cells, in this work we present a new approach that allows us to get accurate values of MCLT. The relationship between MCLT in p-region and n-region both before and after irradiation has been determined by the new method. The validity and accuracy of this approach are justified by the fact that the degradation parameters that fit the experimental data are the same for both short-circuit current and the open-circuit voltages. This method is applied to the p + /n-InGaP solar cell under 1 MeV electron irradiation

Surveying ethnic minorities

NARCIS (Netherlands)

Joost Kappelhof

2015-01-01

Obtaining accurate survey data on ethnic minorities is not easy. Ethnic minorities are usually underrepresented in surveys, and it is moreover not certain that those who do take part in surveys are representative of the group the researcher is interested in. For example, is it only people with

Uptake and incorporation of labeled tryptophan isomers into IAA in the jsR1 mutant of Lemna gibba

International Nuclear Information System (INIS)

Baldi, B.G.; Maher, B.R.; Cohen, J.D.

1989-01-01

Analyses of the IAA-overproducing mutant of Lemna have been initiated in order to study in vivo biosynthesis of IAA. Using radiolabelled tryptophan isomers prepared from commercial sources of 14 C-D,L tryptophan by chiral separation kinetics of uptake of L and D tryptophan were determined for sterile cultures of individual jsR 1 four-frond colonies. Over a 24 h period, about 50% of the radioactivity from 14 C-L-TRP in media, or about 25% from 14 C-D-TRP, was found in the plant tissue. Maximal rates of uptake were seen in the first six hors for both isomers. Endogenous levels of tryptophan determined in jsR 1 as measures of pool sizes in vivo show 5 to 10 ug/g FW total tryptophan with less than 1% in the D isomer form. Information on uptake and endogenous pool sizes of tryptophan isomers is being used for feeding of stable isotope labeled tryptophan ( 13 C, 14 N) to jsR 1 at physiological levels. Analyses of incorporation of label into IAA using GC-MS and high resolution mass spectrometry are currently underway

PRODUCCIÓN DE LA MACRÓFITA ACUÁTICA Lemna perpusilla UTILIZANDO AGUA RESIDUAL DE UNA INSTALACIÓN PORCINA, CON PROPÓSITOS PARA PRODUCCIÓN DE BIOMASA PARA ACUACULTURA

Directory of Open Access Journals (Sweden)

Pablos Reyes DP

2011-01-01

Full Text Available Una problemática ambiental impor- tante en instalaciones porcinas es la producción de excretas con alta concentración de nutrientes y su deposición en el ecosistema. Una alternativa para la biorremediación de dicha problemática es utilizar las excretas para la producción de plantas acuáticas que tengan una alta tasa de captación de nutrientes, tal como Lemna perpusilla. En el presente estudio se desarrollaron dos experimentos con el objetivo de estudiar el efecto de la época del año y el tiempo de cosecha sobre la biomasa, composición química y el rendimiento de nutrientes. En el experimento I (enero a abril se utilizó una dosis de fertilización de 20 Lm-2 por cada 20 días y se manejó una densidad de siembra de 200 gm-2, realizando cosechas cada 10 días. Mientras que en el experimento II (mayo a ju- nio se utilizó la misma dosis de fertilización y densidad de siembra, pero cosechando cada seis días. Durante el desarrollo experimental (enero-junio Lemna perpusilla presentó bajo contenido de materia seca (6.87 a 8.87% y fi- bra (11.67 a 12.89%, pero alto contenido de proteína (26.02 a 27.41%. Se determinó que la época y tiempo de cosecha afectan significati- vamente la cosecha total, composición química y rendimiento de nutrientes. Las variables cli- máticas que más influyeron sobre la cosecha total fueron las horas luz y precipitación. Mien- tras que el rendimiento en nutrientes es princi- palmente afectada por la temperatura, hume- dad relativa, horas luz y precipitación.

THE NATIONAL MINORITY CONSULTATIVE MECHANISMS - THE COUNCILS OF NATIONAL MINORITIES IN BOSNIA AND HERZEGOVINA

Directory of Open Access Journals (Sweden)

Aleksandar Čorni

2016-09-01

Full Text Available The article tries to explore the practical application of the soft law, in concrete terms, the documents adopted by the Organization for Security and Co-operation in Europe, referring to the models of participation of national minorities in public life in the case of Bosnia and Herzegovina. The objective of the research was to assess the legal and political grounds for functioning national minority councils as participation and consultative mechanisms, scope of responsibilities and capacities in relation to their effectiveness and impact and to identify relevant good practices on such mechanisms. The political and decision-making structures in Bosnia and Herzegovina demonstrated lack of actual commitment to the realization of the rights of minorities referring to participation in decision-making processes. Bearing in mind formal position within parliaments, visibility, and a significant promotional capacity for presence in the public sphere, the councils on national minorities may represent a significant body and channel for the minority – majority dialogue. However, at the moment, the national minority councils’ capacity to ensure participation of national minorities in Bosnian political life and their influence in decision-making process remains insufficient. In general, the consultative mechanisms, within their mandated responsibilities, have had insignificant and minimal impact on the practical, political and legislative segment.

Processing Methodology and Dialectological Aspects of the Dictionary of Moravian and Silesian Anoikonyms (Minor Place Names)

Czech Academy of Sciences Publication Activity Database

Čižmárová, Libuše

2010-01-01

Roč. 3, č. 1 (2010), s. 183-195 ISSN 1855-6302 Institutional research plan: CEZ:AV0Z90610518 Keywords : onomastics, dialectology * electronic dictionary * anoikonyms * digitization * Moravia * Silesia * minor place names Subject RIV: AI - Linguistics

Exploring Discrimination and Mental Health Disparities Faced By Black Sexual Minority Women Using a Minority Stress Framework.

Science.gov (United States)

Calabrese, Sarah K; Meyer, Ilan H; Overstreet, Nicole M; Haile, Rahwa; Hansen, Nathan B

2015-09-01

Black sexual minority women are triply marginalized due to their race, gender, and sexual orientation. We compared three dimensions of discrimination-frequency (regularity of occurrences), scope (number of types of discriminatory acts experienced), and number of bases (number of social statuses to which discrimination was attributed)-and self-reported mental health (depressive symptoms, psychological well-being, and social well-being) between 64 Black sexual minority women and each of two groups sharing two of three marginalized statuses: (a) 67 White sexual minority women and (b) 67 Black sexual minority men. Black sexual minority women reported greater discrimination frequency, scope, and number of bases and poorer psychological and social well-being than White sexual minority women and more discrimination bases, a higher level of depressive symptoms, and poorer social well-being than Black sexual minority men. We then tested and contrasted dimensions of discrimination as mediators between social status (race or gender) and mental health outcomes. Discrimination frequency and scope mediated the association between race and mental health, with a stronger effect via frequency among sexual minority women. Number of discrimination bases mediated the association between gender and mental health among Black sexual minorities. Future research and clinical practice would benefit from considering Black sexual minority women's mental health in a multidimensional minority stress context.

Sexual minority-related victimization as a mediator of mental health disparities in sexual minority youth: a longitudinal analysis.

Science.gov (United States)

Burton, Chad M; Marshal, Michael P; Chisolm, Deena J; Sucato, Gina S; Friedman, Mark S

2013-03-01

Sexual minority youth (youth who are attracted to the same sex or endorse a gay/lesbian/bisexual identity) report significantly higher rates of depression and suicidality than heterosexual youth. The minority stress hypothesis contends that the stigma and discrimination experienced by sexual minority youth create a hostile social environment that can lead to chronic stress and mental health problems. The present study used longitudinal mediation models to directly test sexual minority-specific victimization as a potential explanatory mechanism of the mental health disparities of sexual minority youth. One hundred ninety-seven adolescents (14-19 years old; 70 % female; 29 % sexual minority) completed measures of sexual minority-specific victimization, depressive symptoms, and suicidality at two time points 6 months apart. Compared to heterosexual youth, sexual minority youth reported higher levels of sexual minority-specific victimization, depressive symptoms, and suicidality. Sexual minority-specific victimization significantly mediated the effect of sexual minority status on depressive symptoms and suicidality. The results support the minority stress hypothesis that targeted harassment and victimization are partly responsible for the higher levels of depressive symptoms and suicidality found in sexual minority youth. This research lends support to public policy initiatives that reduce bullying and hate crimes because reducing victimization can have a significant impact on the health and well-being of sexual minority youth.

Electronic structure of lanthanide scandates

Science.gov (United States)

Mizzi, Christopher A.; Koirala, Pratik; Marks, Laurence D.

2018-02-01

X-ray photoelectron spectroscopy, ultraviolet photoelectron spectroscopy, and density functional theory calculations were used to study the electronic structure of three lanthanide scandates: GdSc O3,TbSc O3 , and DySc O3 . X-ray photoelectron spectra simulated from first-principles calculations using a combination of on-site hybrid and GGA +U methods were found to be in good agreement with experimental x-ray photoelectron spectra. The hybrid method was used to model the ground state electronic structure and the GGA +U method accounted for the shift of valence state energies due to photoelectron emission via a Slater-Janak transition state approach. From these results, the lanthanide scandate valence bands were determined to be composed of Ln 4 f ,O 2 p , and Sc 3 d states, in agreement with previous work. However, contrary to previous work the minority Ln 4 f states were found to be located closer to, and in some cases at, the valence band maximum. This suggests that minority Ln 4 f electrons may play a larger role in lanthanide scandate properties than previously thought.

The impact of minority stress on mental health and substance use among sexual minority women.

Science.gov (United States)

Lehavot, Keren; Simoni, Jane M

2011-04-01

We examined the direct and indirect impact of minority stress on mental health and substance use among sexual minority women. A combination of snowball and targeted sampling strategies was used to recruit lesbian and bisexual women (N = 1,381) for a cross-sectional, online survey. Participants (M age = 33.54 years; 74% White) completed a questionnaire assessing gender expression, minority stressors (i.e., victimization, internalized homophobia, and concealment), social-psychological resources (i.e., social support, spirituality), and health-related outcomes. We used structural equation modeling to test associations among these factors, with gender expression as an antecedent and social-psychological resources as a mediator between minority stress and health. The final model demonstrated acceptable fit, χ²(79) = 414.00, p accounting for significant portions of the variance in mental health problems (56%) and substance use (14%), as well as the mediator social-psychological resources (24%). Beyond indirect effects of minority stress on health outcomes, direct links emerged between victimization and substance use and between internalized homophobia and substance use. Findings indicate a significant impact of minority stressors and social-psychological resources on mental health and substance use among sexual minority women. The results improve understanding of the distinct role of various minority stressors and their mechanisms on health outcomes. Health care professionals should assess for minority stress and coping resources and refer for evidence-based psychosocial treatments. (c) 2011 APA, all rights reserved.

Comparative evaluation of the effectiveness of electronic dental anesthesia with 2% lignocaine in various minor pediatric dental procedures: A clinical study

Directory of Open Access Journals (Sweden)

Abhishek Dhindsa

2011-01-01

Full Text Available One of the most distressing aspects of dentistry for pediatric patients is the fear and anxiety caused by the dental environment, particularly the dental injection. The application and induction of local anesthetics has always been a difficult task, and this demands an alternative method that is convenient and effective. Electronic dental anesthesia, based on the principal of transcutaneous electric nerve stimulation (TENS, promises to be a viable mode of pain control during various pediatric clinical procedures. Therefore, the aim of the present study was to evaluate the effectiveness of TENS and to compare its efficacy with 2% lignocaine during various minor pediatric dental procedures. Pain, comfort and effectiveness of both the anesthetics were evaluated using various scales and no significant difference was observed between 2% lignocaine and TENS in the various pain scales, while TENS was perceived to be significantly effective in comfort and efficacy as judged by the operator and quite comfortable as judged by the patient himself/herself.

Socioeconomic status and parenting in ethnic minority families: testing a minority family stress model.

Science.gov (United States)

Emmen, Rosanneke A G; Malda, Maike; Mesman, Judi; van Ijzendoorn, Marinus H; Prevoo, Mariëlle J L; Yeniad, Nihal

2013-12-01

According to the family stress model (Conger & Donnellan, 2007), low socioeconomic status (SES) predicts less-than-optimal parenting through family stress. Minority families generally come from lower SES backgrounds than majority families, and may experience additional stressors associated with their minority status, such as acculturation stress. The primary goal of this study was to test a minority family stress model with a general family stress pathway, as well as a pathway specific to ethnic minority families. The sample consisted of 107 Turkish-Dutch mothers and their 5- to 6-year-old children, and positive parenting was observed during a 7-min problem-solving task. In addition, mothers reported their daily hassles, psychological distress, and acculturation stress. The relation between SES and positive parenting was partially mediated by both general maternal psychological stress and maternal acculturation stress. Our study contributes to the argument that stressors specific to minority status should be considered in addition to more general demographic and family stressors in understanding parenting behavior in ethnic minority families.

Social Interaction and the Minority-Majority Earnings Inequality : Why Being a Minority Hurts but being a big Minority Hurts More

NARCIS (Netherlands)

Kahanec, M.

2004-01-01

Empirical findings that minorities typically attain lower economic status than majorities and that relatively larger minorities perform worse than smaller ones pose a challenge to economics.To explain this scale puzzle, I model an economy where the society is bifurcated into two social groups that

Direct minority carrier transport characterization of InAs/InAsSb superlattice nBn photodetectors

International Nuclear Information System (INIS)

Zuo, Daniel; Liu, Runyu; Wasserman, Daniel; Mabon, James; He, Zhao-Yu; Liu, Shi; Zhang, Yong-Hang; Kadlec, Emil A.; Olson, Benjamin V.; Shaner, Eric A.

2015-01-01

We present an extensive characterization of the minority carrier transport properties in an nBn mid-wave infrared detector incorporating a Ga-free InAs/InAsSb type-II superlattice as the absorbing region. Using a modified electron beam induced current technique in conjunction with time-resolved photoluminescence, we were able to determine several important transport parameters of the absorber region in the device, which uses a barrier layer to reduce dark current. For a device at liquid He temperatures, we report a minority carrier diffusion length of 750 nm and a minority carrier lifetime of 200 ns, with a vertical diffusivity of 3 × 10 −2  cm 2 /s. We also report on the device's optical response characteristics at 78 K

Exploring Discrimination and Mental Health Disparities Faced By Black Sexual Minority Women Using a Minority Stress Framework

Science.gov (United States)

Calabrese, Sarah K.; Meyer, Ilan H.; Overstreet, Nicole M.; Haile, Rahwa; Hansen, Nathan B.

2015-01-01

Black sexual minority women are triply marginalized due to their race, gender, and sexual orientation. We compared three dimensions of discrimination—frequency (regularity of occurrences), scope (number of types of discriminatory acts experienced), and number of bases (number of social statuses to which discrimination was attributed)—and self-reported mental health (depressive symptoms, psychological well-being, and social well-being) between 64 Black sexual minority women and each of two groups sharing two of three marginalized statuses: (a) 67 White sexual minority women and (b) 67 Black sexual minority men. Black sexual minority women reported greater discrimination frequency, scope, and number of bases and poorer psychological and social well-being than White sexual minority women and more discrimination bases, a higher level of depressive symptoms, and poorer social well-being than Black sexual minority men. We then tested and contrasted dimensions of discrimination as mediators between social status (race or gender) and mental health outcomes. Discrimination frequency and scope mediated the association between race and mental health, with a stronger effect via frequency among sexual minority women. Number of discrimination bases mediated the association between gender and mental health among Black sexual minorities. Future research and clinical practice would benefit from considering Black sexual minority women's mental health in a multidimensional minority stress context. PMID:26424904

The Economics of Minorities

Science.gov (United States)

Coles, Flournoy A., Jr.

1973-01-01

This article discusses some of the more important economic problems of minorities in the United States, identifying the economics of minorities with the economics of poverty, discrimination, exploitation, urban life, and alienation. (JM)

Mineralization of Surfactants by Microbiota of Aquatic Plants

OpenAIRE

Federle, Thomas W.; Schwab, Burney S.

1989-01-01

The biodegradation of linear alkylbenzene sulfonate (LAS) and linear alcohol ethoxylate (LAE) by the microbiota associated with duckweed (Lemna minor) and the roots of cattail (Typha latifolia) was investigated. Plants were obtained from a pristine pond and a pond receiving wastewater from a rural laundromat. Cattail roots and duckweed plants were incubated in vessels containing sterile water amended with [14C]LAS, [14C]LAE, or 14C-labeled mixed amino acids (MAA). Evolution of 14CO2 was deter...

EFECTOS DEL MERCURIO SOBRE ALGUNAS PLANTAS ACUÁTICAS TROPICALES

OpenAIRE

Posada, Martha Isabel; Arroyave, María del Pilar

2006-01-01

El presente artículo es una descripción de los efectos del mercurio sobre algunas plantas acuáticas tropicales y sobre los ecosistemas donde habitan. Adicionalmente, se recomienda un protocolo para realizar pruebas de toxicidad con la lenteja de agua (Lemna minor) y se presentan los resultados de los preensayos con diferentes concentraciones de sales de mercurio en condiciones de laboratorio. Se encontró que la biodisponibilidad del mercurio depende de factores que facilitan la disolución del...

Electron heating in JET by ICRH

International Nuclear Information System (INIS)

Cordey, J.G.; Christiansen, J.P.; Core, W.G.F.; Cotrell, G.A.; Eriksson, L.G.; Kovanen, M.A.; Lomas, P.; Start, D.F.H.; Taroni, A.; Tibone, F.

1991-01-01

Several ICRH experiments carried out on JET during the period 1988-90 have been directed specifically at raising the electron temperature to a high value by maximizing the total input power per particle (P tot /n). It has been found that the electron temperature saturates around 12-14 keV in sharp contrast to NBI ion heating experiments in which ion temperatures exceed 25 keV. Initial calculations suggested that this saturation was due to strongly enhanced transport in the central region. It is shown in this paper that the saturation is due to a lack of heating in the plasma center. The power input to electrons in an ICRF minority heating scheme is mainly via collisional transfer from the minority fast ions and a main problem is to maintain a peaked profile of fast ions. In the present experiments the highest fast ion energy content 4MJ has been achieved with a He 3 minority scheme, the equivalent fast ion toroidal β is 8%; electron temperatures in the range 11-14 keV are attained in these pulses. There are several possible physical effects that can give rise to the broadening of the fast ion radial profile: sawteeth, fishbones, fast ion finite orbit effects and Alfven or drift wave turbulence driven by the large gradients of fast ion pressure (discussed in section IV). The existence of such phenomena in many JET pulses means that the calculation of the power input profile by codes which contain purely classical collisional processes can be misleading. Hence an alternative approach is developed in section II; the measured fast ion energy is used directly to evaluate the power input to the central region; the scaling of the electron temperature with the actual power per particle can therefore be determined (section III). (author) 6 refs., 5 figs

Minority-carrier transport in InGaAsSb thermophotovoltaic diodes

International Nuclear Information System (INIS)

Charache, G.; Martinelli, R.U.; Garbuzov, D.Z.; Lee, H.; Morris, N.; Odubanjo, T.; Connolly, J.C.

1997-05-01

Uncoated InGaAsSb/GaSb thermophotovoltaic (TPV) diodes with 0.56 eV (2.2 microm) bandgaps exhibit external quantum efficiencies of 59% at 2 microm. The devices have electron diffusion lengths as long as 29 microm in 8-microm-wide p-InGaAsSb layers and hole diffusion lengths of 3 microm in 6-microm-wide n-InGaAsSb layers. The electron and hole diffusion lengths appear to increase with increasing p- and n-layer widths. At 632.8 nm the internal quantum efficiencies of diodes with 1- to 8-microm-wide p-layers are above 89% and are independent of the p-layer width, indicating long electron diffusion lengths. InGaAsSb has, therefore, excellent minority carrier transport properties that are well suited to efficient TPV diode operation. The structures were grown by molecular-beam epitaxy

Evolution of the electron temperature profile of ohmically heated plasmas in TFTR

International Nuclear Information System (INIS)

Taylor, G.; Efthimion, P.C.; Arunasalam, V.

1985-08-01

Blackbody electron cyclotron emission was used to ascertain and study the evolution and behavior of the electron temperature profile in ohmically heated plasmas in the Tokamak Fusion Test Reactor (TFTR). The emission was measured with absolutely calibrated millimeter wavelength radiometers. The temperature profile normalized to the central temperature and minor radius is observed to broaden substantially with decreasing limiter safety factor q/sub a/, and is insensitive to the plasma minor radius. Sawtooth activity was seen in the core of most TFTR discharges and appeared to be associated with a flattening of the electron temperature profile within the plasma core where q less than or equal to 1. Two types of sawtooth behavior were identified in large TFTR plasmas (minor radius, a less than or equal to 0.8 m) : a typically 35 to 40 msec period ''normal'' sawtooth, and a ''compound'' sawtooth with 70 to 80 msec period

Variation of minority charge carrier lifetime in high-resistance p-type silicon under irradiation

International Nuclear Information System (INIS)

Basheleishvili, Z.V.; Garnyk, V.S.; Gorin, S.N.; Pagava, T.A.

1984-01-01

The minority carrier lifetime (tau) variation was studied in the process of p-type silicon bombardment with fast 8 MeV electrons. The irradiation and all measurements were carried out at room temperature. The tau quantity was measured by the photoconductivity attenuation method at a low injection level 20% measurement error; the resistivity was measured by the four-probe method (10% error). The resistivity and minority charge carrier lifetime tau are shown to increase with the exposure dose. It is supposed that as radiation dose increases, the rearrangement of the centres responsible for reducing the lifetime occurs and results in a tau increase in the material being irradiated, however the tau value observed in the original samples is not attained. The restoration of the minority carrier lifetime in p-type high-resistance silicon with a growing exposure dose might proceed due to reduction in the free carrier concentration

The Importance of Minority Teachers: Student Perceptions of Minority versus White Teachers

Science.gov (United States)

Cherng, Hua-Yu Sebastian; Halpin, Peter F.

2016-01-01

The demographic divide between teachers and students is of growing public concern. However, few studies have explicitly addressed the common argument that students, and particularly minority students, have more favorable perceptions of minority versus White teachers. Using data from the Measure of Effective Teaching study, we find that students…

The BCLA Minor: Business, Communication, and Liberal Arts Minor at Towson University

Science.gov (United States)

Mahin, Linda

2008-01-01

In this article, the author describes a cross-disciplinary minor that combines elements of business, communication, and the liberal arts. The BCLA Minor enhances employment opportunities and cultural awareness for students with majors in the Colleges of Business and Economics, Fine Arts and Communication, and Liberal Arts by integrating the…

Institutional Investors as Minority Shareholders

OpenAIRE

Assaf Hamdani; Yishay Yafeh

2013-01-01

We examine the link between minority shareholders' rights and corporate governance by studying institutional investors' voting patterns in a concentrated ownership environment. Institutions rarely vote against insider-sponsored proposals even when the law empowers the minority. Institutions vote against compensation-related proposals more often than against related party transactions even when minority shareholders cannot influence outcomes. Potentially conflicted institutions are more likely...

Self-Esteem Comparisons among Intellectually Gifted Minority/Non-Minority Junior High Students.

Science.gov (United States)

Legin-Bucell, Cynthia; And Others

Differences in self-esteem between 48 minority and 62 non-minority intellectually gifted and 75 intellectually average junior-high students were assessed using the Coopersmith Self-Esteem Inventory. Results indicated a higher level of self-esteem for the gifted students than for the control group. Significant differences were also found to exist…

Diurnal change of light-dependent uridine incorporation into RNA in a log-day duckweed, Lemna gibba G3

International Nuclear Information System (INIS)

Nakashima, Hideaki

1975-01-01

Light-dependent incorporation during subjective day and night of radioactive uridine into RNA of a long-day duckweed, Lemna gibba G3, was examined. When the dark treatment was started from the subjective night phase, the activity of uridine incorporation dropped approximately by half only after the very subjective night phase had passed or with the commencement of the subsequent subjective day phase. However, when the dark treatment was started from the subjective day phase, the incorporating activity promptly began to decrease and the inhibition increased with the length of the dark period until a final steady level (also at ca. 50% of the initial level) was reached after 24 hr of darkness. These two phases of different light sensitivities recurred daily under control of the physiological clock and the rhythm was reset by a light-on signal. The lowered incorporating activity due to the darkened day phase was recovered completely by a 12-hr or even 15-min white light period perturbing the succeeding night phase. That the incorporation of uridine in every RNA species, especially in chloroplast ribosomal RNA, was lowered by dark treatment of the day and night phases, was disclosed by MAK column chromatography and acrylamide gel electrophoresis. (author)

Minority stressors, rumination, and psychological distress in monozygotic twins discordant for sexual minority status.

Science.gov (United States)

Timmins, Liam; Rimes, Katharine A; Rahman, Qazi

2017-11-07

Lesbian, gay, and bisexual (LGB) individuals report higher levels of depression and anxiety than heterosexual people. Genetic factors may be a 'common cause' of sexual minority status and psychological distress. Alternatively, these may be correlated because of non-genetic environmental factors (e.g. minority stressors). This study investigated minority stressors and distress in monozygotic twins discordant for sexual minority status. This design provides a test of the role of non-shared environmental factors while minimizing differences due to genetics. Thirty-eight twin pairs in which one was heterosexual and the other was LGB completed a survey. Differences between twin pairs in minority stressors, rumination, psychological distress, and gender non-conformity were examined. Associations between these variables were also tested. Although there were no significant group differences for distress, LGB twins had higher rumination, a vulnerability factor for distress, than heterosexual co-twins. LGB twins also had higher scores than heterosexual co-twins on expectations of rejection, active concealment, self-stigma, prejudice events, childhood gender non-conformity, and lower scores on sexual orientation disclosure. Differences between twin pairs in rumination were positively associated with differences in acceptance concerns and self-stigma. Finally, self-stigma was positively associated with rumination in the full sample of heterosexual co-twins and microaggressions were positively associated with rumination when looking at exclusively heterosexual co-twins. These results support environmental factors as a causal explanation for disparities in rumination between LGB and heterosexual individuals. These factors likely include minority stressors. Rumination may also be associated with minority stressors in heterosexual MZ co-twins of LGB individuals.

Defining minors' abortion rights.

Science.gov (United States)

Rhodes, A M

1988-01-01

The right to abortion is confirmed in the Roe versus Wade case, by the US Supreme Court. It is a fundamental right of privacy but not an absolute right, and must consider state interests. During the first trimester of pregnancy abortion is a decision of the woman and her doctor. During the second trimester of pregnancy the state may control the abortion practice to protect the mothers health, and in the last trimester, it may prohibit abortion, except in cases where the mother's life or health are in danger. The states enacted laws, including one that required parents to give written consent for a unmarried minor's abortion. This law was struck down by the US Court, but laws on notification were upheld as long as there was alternative procedures where the minor's interests are upheld. Many of these law have been challenged successfully, where the minor was judged mature and where it served her best interests. The state must enact laws on parental notification that take into consideration basic rights of the minor woman. Health professionals and workers should be aware of these laws and should encourage the minor to let parents in on the decision making process where possible.

Age verification cards fail to fully prevent minors from accessing tobacco products.

Science.gov (United States)

Kanda, Hideyuki; Osaki, Yoneatsu; Ohida, Takashi; Kaneita, Yoshitaka; Munezawa, Takeshi

2011-03-01

Proper age verification can prevent minors from accessing tobacco products. For this reason, electronic locking devices based on a proof-of age system utilising cards were installed in almost every tobacco vending machine across Japan and Germany to restrict sales to minors. We aimed to clarify the associations between amount smoked by high school students and the usage of age verification cards by conducting a nationwide cross-sectional survey of students in Japan. This survey was conducted in 2008. We asked high school students, aged 13-18 years, in Japan about their smoking behaviour, where they purchase cigarettes, if or if not they have used age verification cards, and if yes, how they obtained this card. As the amount smoked increased, the prevalence of purchasing cigarettes from vending machines also rose for both males and females. The percentage of those with experience of using an age verification card was also higher among those who smoked more. Somebody outside of family was the top source of obtaining cards. Surprisingly, around 5% of males and females belonging to the group with highest smoking levels applied for cards themselves. Age verification cards cannot fully prevent minors from accessing tobacco products. These findings suggest that a total ban of tobacco vending machines, not an age verification system, is needed to prevent sales to minors.

Minority students benefit from mentoring programs.

Science.gov (United States)

Cullen, D L; Rodak, B; Fitzgerald, N; Baker, S

1993-01-01

Mentoring has been proposed as one strategy to attract minority students to the radiologic sciences profession. This case study describes a minority mentoring program conducted for pre-radiologic science students at a Midwestern university during the 1991-92 academic year. Ten minority radiologic science students enrolled in the mentoring program. The study showed that mentoring may be a viable option to serve the special needs of minorities for recruitment and retention.

Monte Carlo simulation study of ICRF minority heating in the large helical device

International Nuclear Information System (INIS)

Murakami, S.; Okamoto, M.; Ohnishi, M.; Okada, H.

1994-01-01

A Monte Carlo simulation code is developed for ion cyclotron range of frequencies (ICRF) heating in helical systems, which takes into account finite beta effects, complicated orbits of high energetic particles, Coulomb collisions and interactions between particles and the applied waves. The code is used to investigate ICRF minority heating in the Large Helical Device (LHD). The configuration of the magnetic fields changes significantly due to finite beta effects in the LHD. The resonance layer position is found to be crucial to the heating efficiency as the plasma beta increases. When the strength of the resonance magnetic field is set to the value at the magnetic axis, a higher heat efficiency is obtained and no clear difference of the heat efficiency due to finite beta effects is found in the high ICRF wave power region. However, the radial profile of the power transferred to majority ions and electrons from minority ions changes because of the deformation of the trapped particle due to the finite beta effects. The heat efficiency is improved if the radial electric field, E r , is positive (E r is directed radially outward) and it is also improved by supplying 3 He minority ions rather than proton minority ions. (author). 26 refs, 11 figs, 2 tabs

/sup 60/Co accumulation by freshwater plants under natural conditions

Energy Technology Data Exchange (ETDEWEB)

Trapeznikov, A V; Trapeznikova, V N [AN SSSR, Sverdlovsk. Inst. Ehkologii Rastenij i Zhivotnykh

1979-03-01

In search for effective bioindicators of radioactive contamination of cooler-reservoirs in atomic power plants the accumulation of /sup 60/Co by four species of higher aquatic plants most widely distributed in the Urals was studied, namely by Elodea canadensis, Ceratophyllum demersum, Lemna minor and Potamogeton pectinatus. It is shown that such plants as Ceratophyllum demersum and Elodea canadensis having the accumulation coefficients of /sup 60/Co 33,500 and 21,500, respectively, can be recommended as bioindicators of this radionuclide in reservoirs contaminated with radioactive cobalt.

On 60Co accumulation by freshwater plants under natural conditions

International Nuclear Information System (INIS)

Trapeznikov, A.V.; Trapeznikova, V.N.

1979-01-01

In search for effective bioindicators of radioactive contamination of cooler-reservoirs in atomic power plants the accumulation of 60 Co by four species of higher aquatic plants most widely distributed in the Urals was studied, namely by Elodea canadensis, Ceratophyllum demersum, Lemna minor and Potamogeton pectinatus. It is shown that such plants as Ceratophyllum demersum and Elodea canadensis having the accumulation coefficients of 60 Co 33,500 and 21,500, respectively, can be recommended as bioindicators of this radionuclide in reservoirs contaminated with radioactive cobalt

Radiation induced mitotic delay and stimulation of growth

International Nuclear Information System (INIS)

Feldmann, A.

1974-01-01

The mechanisms responsible for the radiation induced mitotic delay and stimulation of growth are discussed in connection with the results of studies in Lemna minor and Lepidium sativum. The action of temperature seems to be of major importance. As many authors suggest that various chemical agents and slight intoxications also affect mitosis in a way similar to that induced by ionizing radiation, the radiation induced stimulation has lost its specific character and approaches might be found for further investigations of this phenomenon. (MG) [de

Efecto del fotoperiodo en la remoción de plomo por Lemna gibba L. (Lemnaceae

Directory of Open Access Journals (Sweden)

Guadalupe Miranda

2015-08-01

Full Text Available El plomo llega a las aguas provenientes de las industrias de baterías, soldaduras, pinturas, etc. causando daños a los seres vivos, por lo que es necesario promover el desarrollo de tecnologías que ayuden a mejorar la calidad de los efluentes y que al mismo tiempo sean adecuadas al contexto socioeconómico del país. En este trabajo se plantea el uso de una angiosperma acuática, la especieLemna gibbade la familia Lemnaceae que tiene un crecimiento exponencial y su cultivo es fácil en laboratorio. Para absorber el plomo (PbNO32 se prepararon cinco concentraciones, a nivel de bioensayo en el laboratorio y bajo el efecto de dos diferentes condiciones de fotoperiodo (luz continua y 12 h luz/12 h oscuridad durante cuatro días, ya que a partir de este día libera el Pb al medio. Los resultados indican que en las dos concentraciones de Pb más bajas (30 y 50 mgl-1, el fotoperiodo 12/12 es más favorable para su absorción (9405 µgl-1más y 18,895 µgl-1 más respectivamente mientras que en las tres restantes (100, 200 y 300 mgl-1 lo fue la condición de luz continua. (6600 µgl-1, 1949 µgl-1, 5587 µgl-1 más respectivamente. Los conocimientos que se derivan de este estudio, permiten optimizar el uso deL. gibbaen el tratamiento terciario de aguas residuales.

SEBACEOUS CYSTS MINOR SURGERY

Directory of Open Access Journals (Sweden)

I Gusti Ayu Agung Laksemi

2013-12-01

Full Text Available Normal 0 false false false EN-US X-NONE X-NONE MicrosoftInternetExplorer4 Minor surgery is small surgery or localized example cut ulcers and boils, cyst excision, and suturing. Somethings that need to be considered in the preparation of the surgery is minor tools, operating rooms and operating tables, lighting, maintenance of tools and equipment, sterilization and desinfection equipment, preparation of patients and anesthesia. In general cysts is walled chamber that consist of fluid, cells and the remaining cells. Cysts are formed not due to inflammation although then be inflamed. Lining of the cysts wall is composed of fibrous tissue and usually coated epithelial cells or endothelial. Cysts formed by dilated glands and closed channels, glands, blood vessels, lymph channels or layers of the epidermis. Contents of the cysts wall consists of the results is serum, lymph, sweat sebum, epithelial cells, the stratum corneum, and hair. /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;}

Multichoice minority game

International Nuclear Information System (INIS)

Ein-Dor, Liat; Metzler, Richard; Kanter, Ido; Kinzel, Wolfgang

2001-01-01

The generalization of the problem of adaptive competition, known as the minority game, to the case of K possible choices for each player, is addressed, and applied to a system of interacting perceptrons with input and output units of a type of K-state Potts spins. An optimal solution of this minority game, as well as the dynamic evolution of the adaptive strategies of the players, are solved analytically for a general K and compared with numerical simulations

Evaluación del riesgo ambiental de carbofurano en bioensayos con organismos no blanco

Directory of Open Access Journals (Sweden)

José Alberto Iannacone

2011-06-01

Full Text Available El carbofurano es uno de los plaguicidas más empleado en la agricultura peruana. El objetivo de este trabajo fue evaluar el riesgo ambiental del carbofurano en bioensayos de toxicidad, sobre once especies no destinatarias. La siguiente secuencia relativa de mayor a menor cocientes de riesgo (CR del carbofurano para los 19 puntos finales de efecto en once especies fue encontrada: Daphnia magna (mortalidad > Lemna minor (inhibición de formación de las hojas > Paracheirodon innesi (nado extraño = P. innesi (incremento del movimiento opercular > Chironomus calligraphus (mortalidad > L. minor (necrosis > P. innesi (mortalidad > L. minor (clorosis > Tetrapygus niger (inhibición de la fecundación > Coturnix japonica (mortalidad > Oncorhynchus mykiss (incremento de coloración > Ceraeochrysa cincta (no eclosión de huevos > O. mykiss (mortalidad con oxígeno > O. mykiss (mortalidad sin oxígeno > Trichogramma pretiosum (mortalidad > C. cincta (mortalidad > T. pretiosum (no emergencia de adultos > Trichogramma pintoi (mortalidad > Beauveria bassiana (inhibición del crecimiento. Los cocientes de riesgo (CR indicaron en todos los casos un alto riesgo del carbofurano principalmente en el ambiente acuático en comparación con el terrestre.Carbofuran is one of the most employed pesticides in Peruvian agriculture. This research aimed to evaluate the risk assessment in bioassays of carbofuran on eleven non-target species. The following relative sequence in decreasing ecotoxicity order in terms of RQ (Risk quotient to carbofuran to 19 end points on 11 species was found: Daphnia magna (mortality > Lemna minor (inhibition of new fronds > Paracheirodon innesi (strange swim = P. innesi (increase of opercula movement > Chironomus calligraphus (mortality > L. minor (necrosis > P. innesi (mortality > L. minor (chlorosis > Tetrapygus niger (inhibition of fertilization> Coturnix japonica (mortality > Oncorhynchus mykiss (increase of coloration > Ceraeochrysa

Ecogenotoxicity testing of aquatic environment by comet assay in plants

Directory of Open Access Journals (Sweden)

Anita Mukherjee

2015-05-01

Full Text Available One of the goals of environmental monitoring is the detection of potentially hazardous compounds in water. We have set up a standard method to apply the Comet assay in aquatic plants that could be of great interest to evaluate cytotoxicity, genotoxicity and oxidative stress on the same species regarded as most sensitive to environmental pollutants. The aim of the present study was to set up of standardized procedure to evaluate genotoxicity in aquatic plants- Ceratophyllum demersum one that is submerged free floating and the other is Lemna minor - a fresh water floating plant by Comet assay. Electrophoresis and unwinding times were adapted to obtain minimum DNA migration evaluated as tail intensity % or tail moment in the control group and, at the same time maximum sensitivity for DNA damage with known genotoxicants. We further investigated the cytotoxicity and oxidative stress induced in the same species. Based on the repeatability of results obtained we suggest that Ceratophyllum, Lemna can serve as model species and Comet assay could be adopted to monitor the eco-genotoxicity of water pollutants.

Autonomy and minority rights

DEFF Research Database (Denmark)

Barten, Ulrike

2008-01-01

on the content of the syllabus. When autonomy is understood in the literal sense, of giving oneself one's own laws, then there is a clear connection. Autonomy is usually connected to politics and a geographically limited territory. Special political rights of minorities - e.g. is the Danish minority party SSW...

Performance of the macrophyte Lemna valdiviana in tertiary pig waste treatment and its contribution to the sustainability of swine production

Directory of Open Access Journals (Sweden)

Flávio R. Lapolli

2008-03-01

Full Text Available The present study aims to contribute to the sustainability of swine production by evaluating usage of the aquatic macrophyte Lemna valdiviana in the tertiary treatment of pig waste. Five assays (1 to 5 in triplicate were conducted using swine effluent with different COD (Chemical Oxygen Demand concentrations: 400, 550, 700, 850 and 1,000mg.L-1, respectively. The trial lasted for 21 days and the evaluated variables were: (a pollutant removal efficiency, (b biomass production and (c plant protein content under the different detention times of 7, 14 and 21 days. In general, assays 1 and 2 (CODs of 400 and 550mg.L-1 presented the best removal efficiencies under a detention time of 21 days. Regarding the purpose of both nutrient removal and production of high protein biomass, assay 3 (COD of 700mg.L-1 showed the best results under 14 days’ detention time (36.81% crude protein. It was established that the use of duckweeds in the tertiary swine waste treatment was able to provide a sustainable alternative regarding its advantages such as effluent polishing, minimization of environmental impact, and production of high protein feed.

Efficiency of removing nitrogen and phosphorous and effects on extracellular enzyme activity in water body by five hydrophytes%5种水生植物的脱氮除磷效果及其对水体胞外酶活的影响

Institute of Scientific and Technical Information of China (English)

汪文强; 王子芳; 高明

2016-01-01

To investigate the role of hydrophytes in the purification of eutrophic water bodies,Trapa quadrispinosa Roxb.,Eichhornia crassipes,Hydrocharis dubia (Bl.) Backer,Ipomoea aquatica Forsk,and Lemna minor L.were planted in treated water to compare their effects on purification and their influence on extracellular enzyme activity.The results showed that all hydrophytes performed well during the purification process.For total nitrogen (TN),the order of removal efficiency was Eichhornia crassipes (81.6％) ＞ Ipomoea aquatica Forsk (72.2％) ＞ Hydrocharis dubia (Bl.) Backer (68.4％) ＞ Trapa quadrispinosa Roxb.(65.8％) ＞ Lemna minor L.(60.2％),and for total phosphorous (TP) removal,the order was Eichhornia crassipes (95.0％) ＞ Ipomoea aquatica Forsk (89.7％) ＞ Hydrocharis dubia (Bl.) Backer (78.4％) ＞ Trapa quadrispinosa Roxb.(77.3％) ＞ Lemna minor L.(70.5％).All five hydrophytes could enhance the activity of extracellular enzymes,and the treatment involving E.crassipes showed the maximum range and peak urease activity (UA) and alkaline phosphatase activity (APA).The range and peak UA were 19.70 μg · mL-1 and 10.33 μg · mL-1,respectively,and for APA,they were 8.12 μg · mL-1 and 5.95 μg · mL-1.The range and peak UA and APA for Ipomoea aquatica Forsk were the next highest.UA and APA were significantly negatively correlated with the concentrations of both NH4-N and dissolved active phosphorus (SRP),and the correlations were between-0.853 and-0.992 and -0.813 and-0.994,respectively.Eichhornia crassipes and Ipomoea aquatica Forsk may work better than Trapa quadrispinosa Roxb,Hydrocharis dubia (Bl.) Backer and Lemna minor L.,and have potential for application in the purification of eutrophic water bodies.%利用静态小区实验研究了菱角(Trapa quadrispinosa Roxb.)、凤眼莲(Eichhornia crassipes.)、水鳖(Hydrocharis dubia (Bl.) Backer)、空心菜(Ipomoea aquatica Forsk)和青萍(Lemna minor L.)5�

Isomer 103Rh excitation in the electron beam

International Nuclear Information System (INIS)

Alpatov, V.G.; Berezkin, V.V.; Vysotskij, S.A.

1993-01-01

Rhodium foil targets were irradiated by a beam of electrons from a linear accelerator containing a minor impurity of bremsstrahlung. X-ray and γ-quanta from decay of 103m Rh isomer states were detected. The ratio of isomer cross section activation by bremsstrahlung, formed in the target, and electrons, equals 89. 7 refs.; 3 figs.; 2 tabs

Wellness of Minority Female Counselor Educators

Science.gov (United States)

Shillingford, M. Ann; Trice-Black, Shannon; Butler, S. Kent

2013-01-01

Minority female counselor educators are faced with numerous challenges. This qualitative study revealed that for female minority counselor educators, these challenges continue to negatively affect their professional and personal experiences. It is through operational wellness practices and optimal balance and functioning that minority female…

Ultrastructure of spermatogenesis in the sea star, Asterina minor.

Science.gov (United States)

Yamagata, A

1988-02-01

The ultrastructural features of spermatogenesis were investigated in the hermaphroditic sea star Asterina minor. The primordial germ cells in the genital rachis contain small clusters of electron-dense material (nuage material) and a stack of annulate lamellae. They also have a flagellum and basal body complex situated close to the Golgi complex. After the development of the genital rachis into the ovotestis, spermatogenic cells increase in number and differentiation begins. Nuage material is observed in spermatogonia, but it gradually disappears in spermatocytes. The annulate lamellae do not exist beyond the early spermatogonial stage. By contrast, a flagellum and basal body complex are found throughout spermatogenesis. The Golgi-derived proacrosomal vesicles appear in the spermatocyte and coalesce to form an acrosomal vesicle in the early spermatid. The process of acrosome formation is as follows: (1) a lamella of endoplasmic reticulum (ER) continuous with the outer nuclear membrane encloses the posterior portion of the acrosomal vesicle; (2) the vesicle attaches to the cell membrane with its anterior portion; (3) periacrosomal material accumulates in the space between the acrosomal vesicle and the ER; (4) the nucleus proper changes its features to surround the acrosome; (5) amorphous, electron-dense material is deposited under the electron-dense disk; and (6) the nucleus forms a hollow opposite the electron-dense material.

Power electronics for renewable energy systems

DEFF Research Database (Denmark)

Iov, Florin; Blaabjerg, Frede

2009-01-01

sources from the conventional, fossil (and short term) based energy sources to renewable energy resources. Another is to use high efficient power electronics in power generation, power transmission/distribution and end-user application. This paper discuss some of the most emerging renewable energy sources......, wind energy and photovoltaics, which by means of power electronics are changing from being minor energy sources to be acting as important power sources in the energy system....

Ion and electron heating in ICRF heating experiments on LHD

Energy Technology Data Exchange (ETDEWEB)

Saito, K. [Nagoya Univ. (Japan). Faculty of Engineering; Kumazawa, R.; Mutoh, T. [National Inst. for Fusion Science, Toki, Gifu (Japan)] [and others

2001-02-01

This paper reports on the Ion Cyclotron Range of Frequency (ICRF) heating conducted in 1999 in the 3rd experimental campaign on the Large Helical Device (LHD) with an emphasis on the optimization of the heating regime. Specifically, an exhaustive study of seven different heating regimes was carried out by changing the RF frequency relative to the magnetic field intensity, and the dependence of the heating efficiency on H-minority concentration was investigated. It was found in the experiment that both ion and electron heating are attainable with the same experimental setup by properly choosing the frequency relative to the magnetic field intensity. In the cases of both electron heating and ion heating, the power absorption efficiency depends on the minority ion concentration. An optimum minority concentration exists in the ion heating case while, in the electron heating case, the efficiency increases with concentration monotonically. A simple model calculation is introduced to provide a heuristic understanding of these experimental results. Among the heating regimes examined in this experiment, one of the ion heating regimes was finally chosen as the optimized heating regime and various high performance discharges were realized with it. (author)

Language, Ethnicity and Education: Case Studies on Immigrant Minority Groups and Immigrant Minority Languages. Multilingual Matters 111.

Science.gov (United States)

Broeder, Peter; Extra, Guus

Immigrant minority groups and immigrant minority languages in Europe are viewed from three perspectives (demographic, sociolinguistic, and educational) through case studies. The first part, using a demographic approach, includes research on immigrant minority groups in population statistics of both European Union and English-dominant countries…

The Minority Game : An Economics Perspective

NARCIS (Netherlands)

Kets, W.

2007-01-01

This paper gives a critical account of the minority game literature. The minority game is a simple congestion game: players need to choose between two options, and those who have selected the option chosen by the minority win. The learning model proposed in this literature seems to differ markedly

14 CFR 152.419 - Minority business.

Science.gov (United States)

2010-01-01

... 14 Aeronautics and Space 3 2010-01-01 2010-01-01 false Minority business. 152.419 Section 152.419... AIRPORT AID PROGRAM Nondiscrimination in Airport Aid Program § 152.419 Minority business. Each person subject to this subpart is required to comply with the Minority Business Enterprise Regulations of the...

Minor burn - first aid - slideshow

Science.gov (United States)

... page: //medlineplus.gov/ency/presentations/100213.htm Minor burn - first aid - series—Procedure, part 1 To use ... out of 2 Overview To treat a minor burn, run cool water over the area of the ...

Electron beam induced electronic transport in alkyl amine-intercalated VOx nanotubes

International Nuclear Information System (INIS)

O'Dwyer, C.; Lavayen, V.; Clavijo-Cedeno, C.; Torres, C.M.S.

2008-01-01

The electron beam induced electronic transport in primary alkyl amine-intercalated V 2 O 5 nanotubes is investigated where the organic amine molecules are employed as molecular conductive wires to an aminosilanized substrate surface and contacted to Au interdigitated electrode contacts. The results demonstrate that the high conductivity of the nanotubes is related to the non-resonant tunnelling through the amine molecules and a reduced polaron hopping conduction through the vanadium oxide itself. Both nanotube networks and individual nanotubes exhibit similarly high conductivities where the minority carrier transport is bias dependent and nanotube diameter invariant. (copyright 2008 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

CRIMINALITY AT MINORS WITH MENTAL DEFICIENCY

Directory of Open Access Journals (Sweden)

Zoran Kitkanj

2009-06-01

Full Text Available The aim of this paper is to present, from penological aspect, the involvement and structure of recidivism at minors with mental deficiency within the whole area of juvenile criminality in Macedonia. The research covers 62 subjects who pay the penalty in juvenile penitentiary or institutional measure directing to correctional institution for minors. Of the total number of minors who hold one of the above-mentioned sanctions, minors with lower average IQ are presented with 56.4%. The shown involvement is in penological terms (refers to minors who hold institutional measure correctional institution for minors or penalty - juvenile penitentiary which does not mean that this category of juvenile delinquents participate in such percent in the total number of reported, accused and convicted minors. According to the research results it can be concluded that falling behind in intellectual development is an indicator for delinquent behavior but in no case it can be crucial or the most important factor for criminality. Of the total number of juvenile delinquents with intellectual deficit, 80% are repeat offenders in criminal legal sense. It is of great concern that 56% of the under average juvenile delinquents defied the law for the first time before the age of 14 years that is as children.

7 CFR 795.12 - Minor children.

Science.gov (United States)

2010-01-01

... 7 Agriculture 7 2010-01-01 2010-01-01 false Minor children. 795.12 Section 795.12 Agriculture... PROVISIONS COMMON TO MORE THAN ONE PROGRAM PAYMENT LIMITATION General § 795.12 Minor children. (a) A minor child and his parents or guardian (or other person responsible for him) shall be considered as one...

浮萍生物富集洛克沙胂与阿散酸的动力学特性研究%Researches on the Kinetic Characteristics of Bioconcentration of Roxarsone and Arsanilic Acid in Duckweed (Lemna minor L.)

Institute of Scientific and Technical Information of China (English)

王付民; 张璐; 陈杖榴

2007-01-01

通过静态法和半静态法研究了浮萍Lemna minor生物富集0.1、0.5、1.0、2.0 mg·L-1洛克沙胂、阿散酸(以砷计)的动力学过程.静态法的研究结果表明:大约55 d,浮萍生物富集各个质量浓度的洛克沙胂、阿散酸均基本达到平衡;0.1、0.5、1.0、2.0 mg·L-1洛克沙胂的生物富集系数(BCF)分别为:3 116.7、1 308.0、548.4、355.0;0.1、0.5、1.0、2.0 mg·L-1阿散酸的BCF分别为:690.0、341.1、255.9、179.8;而且浮萍对各个质量浓度的洛克沙胂、阿散酸的BCF随水体浓度升高而减小.半静态法研究结果表明:浮萍对洛克沙胂、阿散酸的生物富集系数(BCF)、吸收速率常数(K1)随水体质量浓度的增大而减小;同等质量浓度的洛克沙胂的吸收速率常数(K1)大于阿散酸.

ICRF power deposition profile and determination of the electron thermal diffusivity by modulation experiments in JET

International Nuclear Information System (INIS)

Gambier, D.J.; Evrard, M.P.; Adam, J.

1990-01-01

The power deposition profile in the ion cyclotron range of frequencies (ICRF) has been investigated experimentally in JET by means of a square wave modulated RF perturbation. The study has been conducted in D(H) and D( 3 He) plasmas for two heating scenarios. In D( 3 He) plasmas and for central heating in a scenario where mode conversion to Bernstein waves is accessible, the direct power deposition profile on electrons has been derived. It accounts for 15% of the total coupled power and extends over 25% of the minor radius. Outside the RF power deposition zone, the electron thermal diffusivity χ e inside the inversion radius surface (r i ) can be estimated through observation of the diffusive electronic transport. In discharges without monster sawteeth and for a low central temperature gradient (∇T e (r ≤ r i ) ≤ ∇T e (r ≥ r i ) approx. = 5 keV·m -1 ) the value obtained is small (approx. =0.24 +- 0.05 m 2 · s -1 ), typically ten times lower than χ e values deduced from heat pulse propagation in similar discharges at radii larger than the inversion radius. For the D(H) minority heating scheme, a large fraction of the ICRF modulated power is absorbed by minority ions, and the minority tail is modulated with a characteristic ion-electron (i-e) slowing-down time. In this scheme, electron heating occurs only through collisions with the minority ion tail and no modulation of the electron temperature is observed in sawtoothing discharges. This is interpreted as a consequence of the long i-e equipartition time, acting as an integrator for the modulated ICRF signal. Finally, a correlation between the time of the sawtooth crash and the periodic turn-off of the ICRF power is found and its consequence for modulation experiments is reviewed. (author). 22 refs, 16 figs

Monte Carlo simulation study of the ICRF minority heating in the Large Helical Device

International Nuclear Information System (INIS)

Murakami, S.; Okamoto, M.; Nakajima, N.; Ohnishi, M.; Okada, H.

1993-10-01

A Monte Carlo simulation code is developed for the ICRF heating in helical systems, which takes into account finite beta effects, complicated orbits of high energetic particles, Coulomb collisions, and interactions between the particles and the applied waves. The code is used to investigate the ICRF minority heating in the Large Helical Device. The configuration of the magnetic fields changes significantly due to finite beta effects in the Large Helical Device. The resonance layer position is found to be crucial to the heating efficiency as the plasma beta increases. When the strength of the resonance magnetic field is set to the value at the magnetic axis, the higher heat efficiency is obtained and no clear difference of the heat efficiency due to the finite beta effects is found at the high ICRF wave power region. However the radial profile of the transferred power to majority ions and electrons from minority ions changes by the deformation of the trapped particle orbits due to the finite beta effects. The heat efficiency is improved if the radial electric field, E r , is positive (E r is directed radially outward) and it is also improved by supplying 3 He minority ions rather than proton minority ions. (author)

Aquatic microcosm assessment of the effects of tylosin on Lemna gibba and Myriophyllum spicatum

Energy Technology Data Exchange (ETDEWEB)

Brain, Richard A. [Centre for Toxicology, Department of Environmental Biology, University of Guelph, Guelph, ON, N1G 2W1 (Canada); Bestari, Ketut [Centre for Toxicology, Department of Environmental Biology, University of Guelph, Guelph, ON, N1G 2W1 (Canada); Sanderson, Hans [Centre for Toxicology, Department of Environmental Biology, University of Guelph, Guelph, ON, N1G 2W1 (Canada); Hanson, Mark L. [Centre for Toxicology, Department of Environmental Biology, University of Guelph, Guelph, ON, N1G 2W1 (Canada); Wilson, Christian J. [Centre for Toxicology, Department of Environmental Biology, University of Guelph, Guelph, ON, N1G 2W1 (Canada); Johnson, David J. [Centre for Toxicology, Department of Environmental Biology, University of Guelph, Guelph, ON, N1G 2W1 (Canada); Sibley, Paul K. [Centre for Toxicology, Department of Environmental Biology, University of Guelph, Guelph, ON, N1G 2W1 (Canada); Solomon, Keith R. [Centre for Toxicology, Department of Environmental Biology, University of Guelph, Guelph, ON, N1G 2W1 (Canada)]. E-mail: ksolomon@uoguelph.ca

2005-02-01

Tylosin is a macrolide antibiotic commonly used for therapeutic treatment and prophylaxis in livestock. As part of a larger ecotoxicological study, the potential phytotoxic effects of tylosin on the rooted macrophyte Myriophyllum spicatum and the floating macrophyte Lemna gibba were assessed under semi-field conditions using 15 12000-L microcosms. Concentrations of 0, 10, 30, 300 {mu}g/L (n = 3), and 600, 1000, and 3000 {mu}g/L (n = 1) were evaluated as part of separate ANOVA and regression analyses over an exposure period of 35 days. Fate of tylosin was monitored over time in the highest three treatments, where dissipation followed pseudo-first order kinetics with associated half-lives ranging from 9 to 10 days. For both M. spicatum and L. gibba, tylosin was found to cause no biologically significant changes to any endpoint assessed compared to controls at a Type I error rate of 0.1. However, subsequent power analyses revealed that there was generally insufficient power to declare that there were no significant differences at a Type II error rate of 0.2. Conclusions concerning biologically significant impacts were therefore further assessed based on other statistical criteria including comparisons of percent differences between replicated treatments and controls, minimum significant and minimum detectable differences, and coefficients of variation. Based on these criteria, at an ecological effect size of >20% change, tylosin was concluded to elicit no biologically or ecologically significant toxicity to M. spicatum or L. gibba. A hazard quotient assessment indicated that tylosin poses little risk to either species of macrophyte, with an HQ value calculated to be nearly three orders of magnitude below 1 (0.002). - Tylosin is not expected to have ecologically significant effects on Ontario freshwater macrophytes.

Aquatic microcosm assessment of the effects of tylosin on Lemna gibba and Myriophyllum spicatum

International Nuclear Information System (INIS)

Brain, Richard A.; Bestari, Ketut; Sanderson, Hans; Hanson, Mark L.; Wilson, Christian J.; Johnson, David J.; Sibley, Paul K.; Solomon, Keith R.

2005-01-01

Tylosin is a macrolide antibiotic commonly used for therapeutic treatment and prophylaxis in livestock. As part of a larger ecotoxicological study, the potential phytotoxic effects of tylosin on the rooted macrophyte Myriophyllum spicatum and the floating macrophyte Lemna gibba were assessed under semi-field conditions using 15 12000-L microcosms. Concentrations of 0, 10, 30, 300 μg/L (n = 3), and 600, 1000, and 3000 μg/L (n = 1) were evaluated as part of separate ANOVA and regression analyses over an exposure period of 35 days. Fate of tylosin was monitored over time in the highest three treatments, where dissipation followed pseudo-first order kinetics with associated half-lives ranging from 9 to 10 days. For both M. spicatum and L. gibba, tylosin was found to cause no biologically significant changes to any endpoint assessed compared to controls at a Type I error rate of 0.1. However, subsequent power analyses revealed that there was generally insufficient power to declare that there were no significant differences at a Type II error rate of 0.2. Conclusions concerning biologically significant impacts were therefore further assessed based on other statistical criteria including comparisons of percent differences between replicated treatments and controls, minimum significant and minimum detectable differences, and coefficients of variation. Based on these criteria, at an ecological effect size of >20% change, tylosin was concluded to elicit no biologically or ecologically significant toxicity to M. spicatum or L. gibba. A hazard quotient assessment indicated that tylosin poses little risk to either species of macrophyte, with an HQ value calculated to be nearly three orders of magnitude below 1 (0.002). - Tylosin is not expected to have ecologically significant effects on Ontario freshwater macrophytes

Teaching minority children hygiene

DEFF Research Database (Denmark)

Rheinländer, Thilde; Samuelsen, Helle; Dalsgaard, Anders

2015-01-01

infrastructures were important barriers for the implementation of safe home child hygiene. Furthermore, the everyday life of highland villages, with parents working away from the households resulted in little daily adult supervision of safe child hygiene practices. While kindergartens were identified......Objectives. Ethnic minority children in Vietnam experience high levels of hygiene- and sanitation-related diseases. Improving hygiene for minority children is therefore vital for improving child health. The study objective was to investigate how kindergarten and home environments influence...... children were further disadvantaged as teaching was only provided in non-minority language. Conclusions. Kindergartens can be important institutions for the promotion of safe hygiene practices among children, but they must invest in the maintenance of hygiene and sanitation infrastructures and adopt...

Sexual Minority-Related Victimization as a Mediator of Mental Health Disparities in Sexual Minority Youth: A Longitudinal Analysis

OpenAIRE

Burton, Chad M.; Marshal, Michael P.; Chisolm, Deena J.; Sucato, Gina S.; Friedman, Mark S.

2013-01-01

Sexual minority youth (youth who are attracted to the same sex or endorse a gay/lesbian/bisexual identity) report significantly higher rates of depression and suicidality than heterosexual youth. The minority stress hypothesis contends that the stigma and discrimination experienced by sexual minority youth create a hostile social environment that can lead to chronic stress and mental health problems. The present study used longitudinal mediation models to directly test sexual minority-specifi...

Legislative vulnerability of minority groups.

Science.gov (United States)

Paula, Carlos Eduardo Artiaga; Silva, Ana Paula da; Bittar, Cléria Maria Lôbo

2017-12-01

Minorities are in an inferior position in society and therefore vulnerable in many aspects. This study analyzes legislative vulnerability and aims to categorize as "weak" or "strong" the protection conferred by law to the following minorities: elderly, disabled, LGBT, Indians, women, children/ adolescents and black people. In order to do so, it was developed a documental research in 30 federal laws in which legal provisions were searched to protect minorities. Next, the articles were organized in the following categories: civil, criminal, administrative, labor and procedural, to be analyzed afterwards. Legal protection was considered "strong" when there were legal provisions that observed the five categories and "weak" when it did not meet this criterion. It was noted that six groups have "strong" legislative protection, which elides the assertion that minorities are outside the law. The exception is the LGBT group, whose legislative protection is weak. In addition, consecrating rights through laws strengthens the institutional channels for minorities to demand their rights. Finally, it was observed that the legislative protection granted tominorities is not homogeneous but rather discriminatory, and there is an interference by the majority group in the rights regulation of vulnerable groups.

Transmission electron microscopy physics of image formation and microanalysis

CERN Document Server

Reimer, Ludwig

1993-01-01

"Transmission Electron Microscopy" presents the theory of image and contrastformation, and the analytical modes in transmission electron microscopy Theprinciples of particle and wave optics of electrons are described Electron-specimen interactions are discussed for evaluating the theory of scattering and phase contrast Also analysed are the kinetical and dynamical theories of electron diffraction and their applications for crystal-structure determination and imaging of lattices and their defects X-ray microanalysis and electron energy-loss spectroscopy are treated as analytical methods The third edition includes a brief discussionof Schottky emission guns, some clarification of minor details, and references to the recent literature

Workplace harassment: double jeopardy for minority women.

Science.gov (United States)

Berdahl, Jennifer L; Moore, Celia

2006-03-01

To date there have been no studies of how both sex and ethnicity might affect the incidence of both sexual and ethnic harassment at work. This article represents an effort to fill this gap. Data from employees at 5 organizations were used to test whether minority women are subject to double jeopardy at work, experiencing the most harassment because they are both women and members of a minority group. The results supported this prediction. Women experienced more sexual harassment than men, minorities experienced more ethnic harassment than Whites, and minority women experienced more harassment overall than majority men, minority men, and majority women.

Minority Capital Resource Handbook. A Guide to Raising Capital for Minority Entrepreneurs. Second Edition.

Science.gov (United States)

Ewing, Samuel D., Jr.; Maloney, Clifton H. W.

This minority capital resource handbook consists of a guide to raising capital for minority entrepreneurs and a listing of sources that provide such capital. The first section deals with the process of raising capital. The realities of raising capital, intermediaries and financial advisors, and assessing needs are outlined. Factors considered in…

Minor actinide transmutation on PWR burnable poison rods

International Nuclear Information System (INIS)

Hu, Wenchao; Liu, Bin; Ouyang, Xiaoping; Tu, Jing; Liu, Fang; Huang, Liming; Fu, Juan; Meng, Haiyan

2015-01-01

Highlights: • Key issues associated with MA transmutation are the appropriate loading pattern. • Commercial PWRs are the only choice to transmute MAs in large scale currently. • Considerable amount of MA can be loaded to PWR without disturbing k eff markedly. • Loading MA to PWR burnable poison rods for transmutation is an optimal loading pattern. - Abstract: Minor actinides are the primary contributors to long term radiotoxicity in spent fuel. The majority of commercial reactors in operation in the world are PWRs, so to study the minor actinide transmutation characteristics in the PWRs and ultimately realize the successful minor actinide transmutation in PWRs are crucial problem in the area of the nuclear waste disposal. The key issues associated with the minor actinide transmutation are the appropriate loading patterns when introducing minor actinides to the PWR core. We study two different minor actinide transmutation materials loading patterns on the PWR burnable poison rods, one is to coat a thin layer of minor actinide in the water gap between the zircaloy cladding and the stainless steel which is filled with water, another one is that minor actinides substitute for burnable poison directly within burnable poison rods. Simulation calculation indicates that the two loading patterns can load approximately equivalent to 5–6 PWR annual minor actinide yields without disturbing the PWR k eff markedly. The PWR k eff can return criticality again by slightly reducing the boric acid concentration in the coolant of PWR or removing some burnable poison rods without coating the minor actinide transmutation materials from PWR core. In other words, loading minor actinide transmutation material to PWR does not consume extra neutron, minor actinide just consumes the neutrons which absorbed by the removed control poisons. Both minor actinide loading patterns are technically feasible; most importantly do not need to modify the configuration of the PWR core and

Happiness and Sexual Minority Status.

Science.gov (United States)

Thomeer, Mieke Beth; Reczek, Corinne

2016-10-01

We used logistic regression on nationally representative data (General Social Survey, N = 10,668 and N = 6680) to examine how sexual minority status related to happiness. We considered two central dimensions of sexual minority status-sexual behavior and sexual identity. We distinguished between same-sex, both-sex, and different-sex-oriented participants. Because individuals transition between sexual behavior categories over the life course (e.g., from both-sex partners to only same-sex partners) and changes in sexual minority status have theoretical associations with well-being, we also tested the associations of transitions with happiness. Results showed that identifying as bisexual, gay, or lesbian, having both male and female partners since age 18, or transitioning to only different-sex partners was negatively related to happiness. Those with only same-sex partners since age 18 or in the past 5 years had similar levels of happiness as those with only different-sex partners since age 18. Additional tests showed that the majority of these happiness differences became non-significant when economic and social resources were included, indicating that the lower happiness was a product of structural and societal forces. Our findings clearly and robustly underscored the importance of taking a multi-faceted approach to understanding sexuality and well-being, demonstrating that not all sexual minority groups experience disadvantaged happiness. Our study calls for more attention to positive aspects of well-being such as happiness in examinations of sexual minorities and suggests that positive psychology and other happiness subfields should consider the role of sexual minority status in shaping happiness.

Happiness and Sexual Minority Status

Science.gov (United States)

Thomeer, Mieke Beth; Reczek, Corinne

2017-01-01

We used logistic regression on nationally representative data (General Social Survey, N = 10,668 and N = 6,680) to examine how sexual minority status related to happiness. We considered two central dimensions of sexual minority status—sexual behavior and sexual identity. We distinguished between same-sex, both-sex, and different-sex oriented participants. Because individuals transition between sexual behavior categories over the life course (e.g., from both-sex partners to only same-sex partners) and changes in sexual minority status have theoretical associations with well-being, we also tested the effects of transitions on happiness. Results showed that identifying as bisexual, gay, or lesbian, having both male and female partners since age 18, or transitioning to only different-sex partners was negatively related to happiness. Those with only same-sex partners since age 18 or in the past five years had similar levels of happiness as those with only different-sex partners since age 18. Additional tests showed that the majority of these happiness differences became non-significant when economic and social resources were included, indicating that the lower happiness was a product of structural and societal forces. Our findings clearly and robustly underscored the importance of taking a multi-faceted approach to understanding sexuality and well-being, demonstrating that not all sexual minority groups experience disadvantaged happiness. Our study calls for more attention to positive aspects of well-being such as happiness in examinations of sexual minorities and suggests that positive psychology and other happiness subfields should consider the role of sexual minority status in shaping happiness. PMID:27102605

Chemical characterisation and analysis of the cell wall polysaccharides of duckweed (Lemna minor).

Science.gov (United States)

Zhao, X; Moates, G K; Wellner, N; Collins, S R A; Coleman, M J; Waldron, K W

2014-10-13

Duckweed is potentially an ideal biofuel feedstock due to its high proportion of cellulose and starch and low lignin content. However, there is little detailed information on the composition and structure of duckweed cell walls relevant to optimising the conversion of duckweed biomass to ethanol and other biorefinery products. This study reports that, for the variety and batch evaluated, carbohydrates constitute 51.2% (w/w) of dry matter while starch accounts for 19.9%. This study, for the first time, analyses duckweed cell wall composition through a detailed sequential extraction. The cell wall is rich in cellulose and also contains 20.3% pectin comprising galacturonan, xylogalacturonan, rhamnogalacturonan; 3.5% hemicellulose comprising xyloglucan and xylan, and 0.03% phenolics. In addition, essential fatty acids (0.6%, α-linolenic and linoleic/linoelaidic acid) and p-coumaric acid (0.015%) respectively are the most abundant fatty acids and phenolics in whole duckweed. Copyright © 2014 Elsevier Ltd. All rights reserved.

Systematic review: barriers and facilitators for minority ethnic groups accessing urgent and prehospital care

OpenAIRE

Phung, Viet-Hai; Windle, Karen; Asghar, Zahid; Ortega, Marishona; Essam, Nadya; Barot, Mukesh; Kai, Joe; Johnson, Mark; Siriwardena, A. Niroshan

2014-01-01

Background Research addressing inequalities has focussed predominantly on primary and acute care. We aimed to identify barriers or facilitators to people from minority ethnic groups accessing prehospital care and to explore the causes and consequences of any differences in delivery. Methodology We conducted a systematic literature review and narrative synthesis. Electronic searches from 2003 through to 2013 identified studies; systematic reviews, randomised controlled trials, quasi-...

Perturbed GUE Minor Process and Warren's Process with Drifts

Science.gov (United States)

Ferrari, Patrik L.; Frings, René

2014-01-01

We consider the minor process of (Hermitian) matrix diffusions with constant diagonal drifts. At any given time, this process is determinantal and we provide an explicit expression for its correlation kernel. This is a measure on the Gelfand-Tsetlin pattern that also appears in a generalization of Warren's process (Electron. J. Probab. 12:573-590, 2007), in which Brownian motions have level-dependent drifts. Finally, we show that this process arises in a diffusion scaling limit from an interacting particle system in the anisotropic KPZ class in 2+1 dimensions introduced in Borodin and Ferrari (Commun. Math. Phys., 2008). Our results generalize the known results for the zero drift situation.

Power Electronics in Wind Turbine Systems

DEFF Research Database (Denmark)

Blaabjerg, Frede; Chen, Zhe; Teodorescu, Remus

2006-01-01

the conventional, fossil (and short term) based energy sources to renewable energy resources. The other is to use high efficient power electronics in power systems, power production and end-user application. This paper discuss the most emerging renewable energy source, wind energy, which by means of power...... electronics is changing from being a minor energy source to be acting as an important power source in the energy system. By that wind power is also getting an added value in the power system operation....

Ethnic minority dropout in economics

NARCIS (Netherlands)

Arnold, I.J.M.

2013-01-01

This paper investigates the first-year study success of minority students in the bachelor program in economics at Erasmus University Rotterdam. We find that the gap in study success between minority and majority students can be attributed to differences in high school education. Students from

Avoidable hospitalization among migrants and ethnic minority groups: a systematic review.

Science.gov (United States)

Dalla Zuanna, Teresa; Spadea, Teresa; Milana, Marzio; Petrelli, Alessio; Cacciani, Laura; Simonato, Lorenzo; Canova, Cristina

2017-10-01

The numbers of migrants living in Europe are growing rapidly, and has become essential to assess their access to primary health care (PHC). Avoidable Hospitalization (AH) rates can reflect differences across migrant and ethnic minority groups in the performance of PHC. We aimed to conduct a systematic review of all published studies on AH comparing separately migrants with natives or different racial/ethnic groups, in Europe and elsewhere. We ran a systematic search for original articles indexed in primary electronic databases on AH among migrants or ethnic minorities. Studies presenting AH rates and/or rate ratios between at least two different ethnic minority groups or between migrants and natives were included. Of the 35 papers considered in the review, 28 (80%) were conducted in the United States, 4 in New Zealand, 2 in Australia, 1 in Singapore, and none in Europe. Most of the studies (91%) used a cross-sectional design. The exposure variable was defined in almost all articles by ethnicity, race, or a combination of the two; country of birth was only used in one Australian study. Most of the studies found significant differences in overall AH rates, with minorities (mainly Black and Hispanics) showing higher rates than non-Hispanic Whites. AH has been used, mostly in the US, to compare different racial/ethnic groups, while it has never been used in Europe to assess migrants' access to PHC. Studies comparing AH rates between migrants and natives in European settings can be helpful in filling this lack of evidence. © The Author 2017. Published by Oxford University Press on behalf of the European Public Health Association. All rights reserved.

Anxiety and depression symptoms in Brazilian sexual minority ecstasy and LSD users

Directory of Open Access Journals (Sweden)

Lysa S. Remy

2017-11-01

Full Text Available Abstract Background This study examined drug use patterns and psychiatric symptoms of anxiety and depression among young Brazilian sexual minority ecstasy and LSD users and compared findings with those reported for their heterosexual peers. Method This cross-sectional study employed targeted sampling and ethnographic mapping approaches via face-to-face interviews conducted at bars and electronic music festivals using an adapted, semi-structured version of the Global Appraisal of Individual Needs questionnaire. The sample comprised 240 male and female young adults who had used ecstasy and/or LSD in the 90 days prior to the interview and who were not on treatment for alcohol and drug abuse. Results Of the 240 subjects enrolled (mean age: 22.9±4.5 years, 28.7% were gay or bisexuals. Multivariate regression analysis showed that the prevalence of depression symptoms in the past 12 months in the sexual minority group was 37% higher than among heterosexuals (prevalence ratio [PR]=1.79; 95% confidence interval [95%CI] 1.03-3.11; p=0.037. Conclusion Strategies should be developed to assess and address individual needs and treatment approaches should be tailored to address depressive symptoms in young, sexual minority club drug users.

Sexual Minority-Related Victimization as a Mediator of Mental Health Disparities in Sexual Minority Youth: A Longitudinal Analysis

Science.gov (United States)

Burton, Chad M.; Marshal, Michael P.; Chisolm, Deena J.; Sucato, Gina S.; Friedman, Mark S.

2013-01-01

Sexual minority youth (youth who are attracted to the same sex or endorse a gay/lesbian/bisexual identity) report significantly higher rates of depression and suicidality than heterosexual youth. The minority stress hypothesis contends that the stigma and discrimination experienced by sexual minority youth create a hostile social environment that…

Dictionary of Minor Planet Names

CERN Document Server

Schmadel, Lutz D

2007-01-01

Dictionary of Minor Planet Names, Fifth Edition, is the official reference for the field of the IAU, which serves as the internationally recognised authority for assigning designations to celestial bodies and any surface features on them. The accelerating rate of the discovery of minor planets has not only made a new edition of this established compendium necessary but has also significantly altered its scope: this thoroughly revised edition concentrates on the approximately 10,000 minor planets that carry a name. It provides authoritative information about the basis for all names of minor planets. In addition to being of practical value for identification purposes, this collection provides a most interesting historical insight into the work of those astronomers who over two centuries vested their affinities in a rich and colorful variety of ingenious names, from heavenly goddesses to more prosaic constructions. The fifth edition serves as the primary reference, with plans for complementary booklets with newl...

Electron excitation of alkali atoms

International Nuclear Information System (INIS)

Ormonde, S.

1979-02-01

The development and testing of a synthesized close-coupling effective model potential ten-channel electron-atom scattering code and some preliminary calculations of resonances in cross sections for the excitation of excited states of potassium by low energy electrons are described. The main results obtained are: identification of 1 S and 1 D structures in excitation cross sections below the 5 2 S threshold of neutral potassium; indications of additional structures - 1 P and 1 D between the 5 2 S and 5 2 D thresholds; and a suggested explanation of anomalously high interstate-electron impact excitation cross sections inferred from experiments on potassium-seeded plasmas. The effective potential model imbedded in the code can be used to simulate any atomic system that can be approximated by a single bound electron outside an ionic core. All that is needed is a set of effective potential parameters--experimental or theoretical. With minor modifications the code could be adapted to calculations of electron scattering by two-electron systems

Self-consistent electronic structure of disordered Fe/sub 0.65/Ni/sub 0.35/

International Nuclear Information System (INIS)

Johnson, D.D.; Pinski, F.J.; Stocks, G.M.

1985-01-01

We present the results of the first ab initio calculation of the electronic structure of the disordered alloy Fe/sub 0.65/Ni/sub 0.35/. The calculation is based on the multiple-scattering coherent-potential approach (KKR-CPA) and is fully self-consistent and spin polarized. Magnetic effects are included within local-spin-density functional theory using the exchange-correlation function of Vosko--Wilk--Nusair. The most striking feature of the calculation is that electrons of different spins experience different degrees of disorder. The minority spin electrons see a very large disorder, whereas the majority spin electrons see little disorder. Consequently, the minority spin density of states is smooth compared to the very structured majority spin density of states. This difference is due to a subtle balance between exchange splitting and charge neutrality

Effectiveness of Recycling Promotion and Education Initiatives among First-Generation Ethnic Minorities in Ontario, Canada

Directory of Open Access Journals (Sweden)

Calvin Lakhan

2016-05-01

Full Text Available This study examines how first-generation ethnic minorities respond to different types of recycling promotion and education campaigns (P&E used by municipalities in Ontario, Canada. A total of eight focus group sessions were conducted over an eight-week period to gauge participant attitudes and responses towards print (newspaper and signs and electronic (websites P&E messaging. Participants were asked to comment on message “recognition”, “clarity”, “the ability to increase recycling awareness” and “the ability to affect changes in recycling behavior”. Results from the focus group sessions suggest that none of the P&E mediums tested were able to increase recycling awareness or change recycling behavior in any meaningful way. First-generation ethnic minorities struggle with recognizing the central theme and purpose of P&E advertisements. Respondents also found existing campaigns excessively complex and confusing, and were not familiar with many of the terms and symbols used in existing P&E messaging. Other findings suggest that ethnic minorities are skeptical and distrustful of the municipalities’ intentions with respect to what they do with the waste after it is collected. The findings from this study lead to the recommendation that municipalities rethink and redesign recycling promotion and education initiatives to better engage minority communities.

Introduction-Minority Language Policy: Theory and Practice

OpenAIRE

Stefan Oeter

2007-01-01

In practice the Charter has created legal standards that work like individual and collective rights and that empower minority language speakers to insist upon education in minority languages, on using the languages before judicial courts and the administration, on claiming a right to receive radio and television programmes in minority languages, and on insisting to be treated in the minority language in hospitals and homes for the elderly, to name only some of the most important guarantees of...

Tobacco sales to minors in Italy.

Science.gov (United States)

Gallus, Silvano; Tramacere, Irene; Zuccaro, Piergiorgio; Colombo, Paolo; La Vecchia, Carlo

2009-01-01

One of the strategies to control tobacco is to limit purchase of cigarettes to minors. To understand the attitudes of Italian adults towards regulations to prevent minors from purchasing tobacco products, we added specific questions to the annual survey on smoking in Italy. During March-April 2007, we conducted a survey on smoking on 3,057 subjects representative of the Italian population aged > or = 15 years. Two specific questions were included, one investigating the attitudes towards the proposed legislation prohibiting purchase of tobacco to individuals under 18 years of age (instead of 16 years) as a policy to reduce smoking prevalence and consumption. The second question asked whether the current tobacco sales-to-minors law was observed. Overall, 78% of Italians believed that a restriction of the current tobacco sales-to-minors law could be moderately to extremely effective as a strategy to decrease smoking prevalence and consumption. More than 90% of Italians reported that they had never seen in their lifetime a retailer refusing to sell cigarettes to an adolescent or requesting the minor's identification or age. A restriction of the legislation, increasing to 18 years the minimum age for purchasing tobacco, would limit access to tobacco products by minors, only if adopted together with systematic and effective enforcement measures.

Minority Stress across the Career-Lifespan Trajectory

Science.gov (United States)

Dispenza, Franco; Brown, Colton; Chastain, Taylor E.

2016-01-01

Sexual minority persons (e.g., lesbian, gay, bisexual, and queer) are likely to encounter "minority stress", such as discrimination, concealment, expectation of rejection, and internalized heterosexism. Minority stress occurs alongside one's lifespan and has considerable implications in the context of the career lifespan trajectory.…

The effect of plasma minor-radius expansion in the current build-up phase of a large tokamak

International Nuclear Information System (INIS)

Kobayashi, Tomofumi; Tazima, Teruhiko; Tani, Keiji; Tamura, Sanae

1977-03-01

A plasma simulation code has been developed to study the plasma current build-up process in JT-60. Plasma simulation is made with a model which represents well overall plasma behavior of the present-day tokamaks. The external electric circuit is taken into consideration in simulation calculation. An emphasis is placed on the simulation of minor-radius expansion of the plasma and behavior of neutral particles in the plasma during current build-up. A calculation with typical parameters of JT-60 shows a week skin distribution in the current density and the electron temperature, if the minor radius of the plasma expands with build-up of the plasma current. (auth.)

Minority Engineering Program Pipeline: A Proposal to Increase Minority Student Enrollment and Retention in Engineering

Science.gov (United States)

Charity, Pamela C.; Klein, Paul B.; Wadhwa, Bhushan

1995-01-01

The Cleveland State University Minority Engineering Program Pipeline consist of programs which foster engineering career awareness, academic enrichment, and professional development for historically underrepresented minority studies. The programs involved are the Access to Careers in Engineering (ACE) Program for high school pre-engineering students: the LINK Program for undergraduate students pursuing degree which include engineering; and the PEP (Pre-calculus Enrichment Program) and EPIC (Enrichment Program in Calculus) mathematics programs for undergraduate academic enrichment. The pipeline is such that high school graduates from the ACE Program who enroll at Cleveland State University in pursuit of engineering degrees are admitted to the LINK Program for undergraduate level support. LINK Program students are among the minority participants who receive mathematics enrichment through the PEP and EPIC Programs for successful completion of their engineering required math courses. THese programs are interdependent and share the goal of preparing minority students for engineering careers by enabling them to achieve academically and obtain college degree and career related experience.

Nutritional composition of minor indigenous fruits

DEFF Research Database (Denmark)

Shajib, Md. Tariqul Islam; Kawser, Mahbuba; Miah, Md. Nuruddin

2013-01-01

In line of the development of a food composition database for Bangladesh, 10 minor indigenous fruits were analysed for their nutrient composition comprising ascorbic acid, carotenoids and mineral values. Nutrient data obtained have been compared with published data reported in different literatur...... values of these minor fruits would make awareness among the people for their mass consumption for healthy life and to grow more minor fruit trees from extinction in order to maintain biodiversity....

Minor actinide transmutation - a waste management option

International Nuclear Information System (INIS)

Koch, L.

1986-01-01

The incentive to recycle minor actinides results from the reduction of the long-term α-radiological risk rather than from a better utilization of the uranium resources. Nevertheless, the gain in generated electricity by minor actinide transmutation in a fast breeder reactor can compensate for the costs of their recovery and make-up into fuel elements. Different recycling options of minor actinides are discussed: transmutation in liquid metal fast breeder reactors (LMFBRs) is possible as long as plutonium is not recycled in light water reactors (LWRs). In this case a minor actinide burner with fuel of different composition has to be introduced. The development of appropriate minor actinide fuels and their properties are described. The irradiation experiments underway or planned are summarized. A review of minor actinide partitioning from the PUREX waste stream is given. From the present constraints of LMFBR technology a reduction of the long-term α-radiological risk by a factor of 200 is deduced relative to that from the direct storage of spent LWR fuel. Though the present accumulation of minor actinides is low, nuclear transmutation may be needed when nuclear energy production has grown. (orig.)

22 CFR 51.28 - Minors.

Science.gov (United States)

2010-04-01

... under § 51.28(a)(5) must be made by a senior passport authorizing officer pursuant to guidance issued by... appearance of the minor is specifically excused by a senior passport authorizing officer pursuant to guidance..., unless the personal appearance of the minor is specifically excused by a senior passport authorizing...

75 FR 81395 - Minority and Women Inclusion

Science.gov (United States)

2010-12-28

... 2590-AA28 Minority and Women Inclusion AGENCIES: Federal Housing Finance Board; Federal Housing Finance... and the inclusion of women and minorities in all activities. The final rule implements the provisions.... It also requires each regulated entity to establish an Office of Minority and Women Inclusion, or...

75 FR 10446 - Minority and Women Inclusion

Science.gov (United States)

2010-03-08

... 2590-AA28 Minority and Women Inclusion AGENCIES: Federal Housing Finance Board; Federal Housing Finance... minority and women inclusion. Section 1116 of the Housing and Economic Recovery Act of 2008 amended section... Loan Banks to promote diversity and the inclusion of women and minorities in all activities...

Minors and Sexting: Legal Implications.

Science.gov (United States)

Lorang, Melissa R; McNiel, Dale E; Binder, Renée L

2016-03-01

Sexting is the sending or forwarding of sexually explicit photographs or videos of the sender or someone known to the sender via cell phone. It has become common practice among young people, as cell phones are being given to adolescents at ever younger ages. Youths often send messages without giving appropriate thought to the content of the images. In studies on the subject, rates of minors who have sent sexual images range from 4 to 25 percent, depending on the age of the youths surveyed, the content of the messages and other factors. Because transferring and viewing sexually explicit material when the subject is a minor can be considered child pornography, there can be serious legal consequences. Several states have enacted legislation to help differentiate between child pornography and sexting by minors. The trend reflected in statutes has been that minors involved in sexting without other exacerbating circumstances should be charged with a less serious offense. There is no clear national consensus on how sexting by minors is adjudicated, and therefore we compared several statutes. Case examples are used to illustrate the range of legal outcomes, from felony charges to no charges. Two sexting episodes that were followed by suicide are described. We also address the role of the forensic mental health professional. © 2016 American Academy of Psychiatry and the Law.

Neodymium partitioning in zirconolite-based glass-ceramics designed for minor actinides immobilization

International Nuclear Information System (INIS)

Loiseau, P.; Caurant, D.; Baffier, N.; Fillet, C.

2000-01-01

This study deals with glass-ceramic matrices designed for the conditioning of minor actinides, in which zirconolite crystals (CaZrTi 2 O 7 ) are homogeneously dispersed in a residual glassy matrix. Good immobilization performances require a high enrichment of actinides in the crystalline phase (double containment principle). Glass-ceramics are obtained by controlled devitrification of an aluminosilicate parent glass containing large amounts of TiO 2 and ZrO 2 . Neodymium was selected to simulate the trivalent minor actinides. Crystallization was performed at 1200 deg. C for various Nd 2 O 3 contents (0 - 10 wt. %). In all cases, zirconolite crystallization is obtained in the bulk of glass-ceramics. The evolution of Nd 3+ location between the crystals and the residual glass was followed by electron spin resonance and optical absorption. Both techniques demonstrate that neodymium is partly incorporated in zirconolite crystals. Moreover, total Nd 2 O 3 content in parent glass has a strong effect on Nd 3+ ions distribution. (authors)

A method to study electron heating during ICRH

International Nuclear Information System (INIS)