Уточнить поиск
Результаты 3071-3080 из 4,308
Substrate-independent luminescent phage-based biosensor to specifically detect enteric bacteria such as E. coli Полный текст
2017
Franche, Nathalie | Vinay, Manon | Ansaldi, Mireille
Water quality is a major safety consideration in environments that are impacted by human activity. The key challenge of the COMBITOX project is to develop a unique instrument that can accommodate several biodetector systems (see the accompanying COMBITOX papers) able to detect different pollutants such as bacteria, toxins, and heavy metals. The output signal chosen by our consortium is based on luminescence detection. Our group recently developed phage-based biosensors using gfp as a reporter gene to detect enteric bacteria in complex environments such as sea water, and the main challenge we faced was to adapt our biodetector to a luminescent signal that could fit the COMBITOX project requirements. Another key point was to use a substrate-independent reporter system in order to avoid substrate addition in the detection prototype. This paper describes the development of a phage-based biodetector using a luminescent and substrate-independent output to detect some enteric bacteria, such as Escherichia coli, in water samples. We have successfully engineered various prototypes using the HK620 and HK97 bacteriophages that use different packaging systems, and both proved functional for the integration of the full luxCDABE operon controlled by two different bacterial promoters. We show that the luxCDABE operon controlled by the PrplU bacterial promoter is the most efficient in terms of signal emission. The emission of luminescence is specific and allows the detection of 10⁴ bacteria per milliliter in 1.5 h post-infection with neither a concentration nor enrichment step.
Показать больше [+] Меньше [-]Exposure to SSRI-type antidepressants increases righting time in the marine snail Ilyanassa obsoleta Полный текст
2017
Fong, Peter | Bury, Taylor B. S. | Donovan, Elizabeth E. | Lambert, Olivia J. | Palmucci, Julia R. | Adamczak, Stephnie K.
Exposure to human antidepressants has been shown to disrupt locomotion and other foot-mediated mechanisms in aquatic snails. We tested the effect of three selective serotonin reuptake inhibitor (SSRI)- and one selective serotonin-norepinephrine reuptake inhibitor (SNRI)-type antidepressants on the righting response in the marine snail, Ilyanassa obsoleta. All four antidepressants (fluoxetine, sertraline, paroxetine, venlafaxine) significantly increased righting time compared with controls with an exposure time as short as 1 h. Dose responses were nonmonotonic with effects seen mainly at the lowest exposure concentrations and shortest duration. The lowest concentration to show an effect was 3.45 μg/L fluoxetine with a 2-h exposure period and is about 3.71 times higher than environmental concentrations. Our results highlight rapid disruption of another foot-mediated behavior in aquatic snails by SSRI-type antidepressants. We discuss these and other reported nonmonotonic dose responses caused by antidepressants in terms of the various possible physiological mechanisms of action in nontarget aquatic species.
Показать больше [+] Меньше [-]Concentration, sources and risk assessment of PAHs in bottom sediments Полный текст
2017
Baran, Agnieszka | Tarnawski, Marek | Urbański, Krzysztof | Klimkowicz-Pawlas, Agnieszka | Spałek, Iwona
Concentration, sources and risk assessment of PAHs in bottom sediments Полный текст
2017
Baran, Agnieszka | Tarnawski, Marek | Urbański, Krzysztof | Klimkowicz-Pawlas, Agnieszka | Spałek, Iwona
The aims of the study were to investigate the concentration, sources and ecological risk of PAHs (polycyclic aromatic hydrocarbons) in bottom sediments collected from nine reservoirs located in south-eastern Poland. The concentration of ∑PAHs in sediments ranged from 150 to 33,900 μg kg⁻¹. The total PAH concentration in the bottom sediments was arranged in the following order: Rybnik > Rzeszów > Brzóza Królewska > Brzóza Stadnicka > Besko > Chechło > Ożanna > Głuchów > Narożniki. BAP was the major compound in sediments from the Besko, Brzóza Stadnicka and Rzeszów reservoirs; FLT in the sediments from the Rybnik, Narożniki, Ożanna and Brzóza Królewska reservoirs; and FLN from the Głuchów and Chechło reservoirs. The major inputs of PAHs were of pyrolytic origin. However, petrogenic sources of PAHs occurred especially in the Chechło and Głuchów reservoirs. The ecological risk assessment indicated that non-adverse effects on the benthic fauna may occur for sediments from the Głuchów, Narozniki and Ożanna reservoirs, while slightly adverse effects were found for sediments from the Brzóza Królewska, Besko, Brzóza Stadnicka and Chechło reservoirs. The other sediments showed moderate (Rzeszów reservoirs) and strong effect (Rybnik reservoir) on biological communities. Individual PAHs such as NAP, PHE, FLT, PYR, BAA, CHR and BAP in sediments from the Rybnik reservoir and BAP in sediments from the Rzeszów reservoirs indicated a higher possibility of occurrence of an adverse ecological effect. PCA analysis found slight difference between the reservoirs in the profile of variable PAHs. Only the sediments from the Rybnik and Chechło reservoirs differ considerably from this grouping.
Показать больше [+] Меньше [-]Concentration, sources and risk assessment of PAHs in bottom sediments Полный текст
Agnieszka Baran | Marek Tarnawski | Krzysztof Urbański | Agnieszka Klimkowicz-Pawlas | Iwona Spałek
The aims of the study were to investigate the concentration, sources and ecological risk of PAHs (polycyclic aromatic hydrocarbons) in bottom sediments collected from nine reservoirs located in south-eastern Poland. The concentration of ∑PAHs in sediments ranged from 150 to 33,900 μg kg−1. The total PAH concentration in the bottom sediments was arranged in the following order: Rybnik > Rzeszów > Brzóza Królewska > Brzóza Stadnicka > Besko > Chechło>Ożanna > Głuchów > Narożniki. BAP was the major compound in sediments from the Besko, Brzóza Stadnicka and Rzeszów reservoirs; FLT in the sediments from the Rybnik, Narożniki, Ożanna and Brzóza Królewska reservoirs; and FLN from the Głuchów and Chechło reservoirs. The major inputs of PAHs were of pyrolytic origin. However, petrogenic sources of PAHs occurred especially in the Chechłoand Głuchów reservoirs. The ecological risk assessment indicated that non-adverse effects on the benthic fauna may occur for sediments from the Głuchów, Narozniki and Ożanna reservoirs, chile slightly adverse effects were found for sediments from the Brzóza Królewska,Besko,Brzóza Stadnickaand Chechłoreservoirs.The other sediments showed moderate (Rzeszów reservoirs) and strong effect (Rybnik reservoir) on biological communities. IndividualPAHssuchasNAP,PHE,FLT,PYR,BAA,CHR and BAP in sediments from the Rybnik reservoir and BAP in sediments from the Rzeszów reservoirs indicated a higher possibility of occurrence of an adverse ecological effect. PCA analysis found slight difference between the reservoirs in the profile of variable PAHs. Only the sediments from the Rybnik and Chechło reservoirs differ considerably from this grouping. | Bottom sediments; PAHs; Source; Ecological risk assessment; PCA | 30 | 23180-23195 | 29
Показать больше [+] Меньше [-]Exogenous application of plant growth regulators (PGRs) induces chilling tolerance in short-duration hybrid maize Полный текст
2017
Waqas, Muhammad Ahmed | Khan, Imran | Akhter, Muhammad Javaid | Noor, Mehmood Ali | Ashraf, Umair
Chilling stress hampers the optimal performance of maize under field conditions precipitously by inducing oxidative stress. To confer the damaging effects of chilling stress, the present study aimed to investigate the effects of some natural and synthetic plant growth regulators, i.e., salicylic acid (SA), thiourea (TU), sorghum water extract (SWE), and moringa leaf extract (MLE) on chilling stress tolerance in autumn maize hybrid. Foliar application of growth regulators at low concentrations was carried out at six leaf (V6) and tasseling stages. An increase in crop growth rate (CGR), leaf area index (LAI), leaf area duration (LAD), plant height (PH), grain yield (GY), and total dry matter accumulation (TDM) was observed in exogenously applied plants as compared to control. In addition, improved physio-biochemical, phenological, and grain nutritional quality attributes were noticed in foliar-treated maize plots as compared to non-treated ones. SA-treated plants reduced 20% electrolyte leakage in cell membrane against control. MLE and SA were proved best in improving total phenolic, relative water (19–23%), and chlorophyll contents among other applications. A similar trend was found for photosynthetic and transpiration rates, whereas MLE and SWE were found better in improving CGR, LAI, LAD, TDM, PH, GY, grains per cob, 1000 grain weight, and biological yield among all treatments including control. TU and MLE have significantly reduced the duration in phenological events of crop at the reproductive stage. MLE, TU, and SA also improved the grain protein, oil, and starch contents as compared to control. Enhanced crop water productivity was also observed in MLE-treated plants. Economic analysis suggested that MLE and SA applications were more economical in inducing chilling stress tolerance under field conditions. Although eliciting behavior of all growth regulators improved morpho-physiological attributes against suboptimal temperature stress conditions, MLE and SA acted as leading agents which proved to be better stress alleviators by improving plant physio-biochemical attributes and maize growth.
Показать больше [+] Меньше [-]The biological response chain to pollution: a case study from the “Italian Triangle of Death” assessed with the liverwort Lunularia cruciata Полный текст
2017
Basile, Adriana | Loppi, Stefano | Piscopo, Marina | Paoli, Luca | Vannini, Andrea | Monaci, Fabrizio | Sorbo, Sergio | Lentini, Marco | Esposito, Sergio
The liverwort Lunularia cruciata, known for being a species tolerant to pollution able to colonize urban areas, was collected in the town of Acerra (South Italy) to investigate the biological effects of air pollution in one of the three vertices of the so-called Italian Triangle of Death. The ultrastructural damages observed by transmission electron microscopy in specimens collected in Acerra were compared with samples collected in the city center of Naples and in a small rural site far from sources of air pollution (Riccia, Molise, Southern Italy). The biological response chain to air pollution was investigated considering vitality, photosynthetic efficiency, heat shock protein 70 (Hsp70) induction and gene expression levels, and chlorophyll degradation and related ultrastructural alterations. Particularly, a significant increment in Hsp70 expression and occurrence, and modifications in the chloroplasts’ ultrastructure can be strictly related to the environmental pollution conditions in the three sites. The results could be interpreted in relation to the use of these parameters as biomarkers for environmental pollution.
Показать больше [+] Меньше [-]Ozone risk assessment for an Alpine larch forest in two vegetative seasons with different approaches: comparison of POD1 and AOT40 Полный текст
2017
Finco, Angelo | Marzuoli, Riccardo | Chiesa, Maria | Gerosa, Giacomo
The upper vegetation belts like larch forests are supposed to be under great pressure because of climate change in the next decades. For this reason, the evaluation of the risks due to abiotic stressors like ozone is a key step. Two different approaches were used here: mapping AOT40 index by means of passive samplers and direct measurements of ozone deposition.Measurements of ozone fluxes using the eddy-correlation technique were carried out for the first time over a larch forest in Paspardo (I) at 1750 m a.s.l. Two field campaigns were run: the first one in 2010 from July to October and the second one in the following year from June to September. Vertical exchange of ozone, energy, and momentum were measured on a tower platform at 26 m above ground level to study fluxes dynamics over this ecosystem. Since the tower was located on a gentle slope, an “ad hoc” methodology was developed to minimize the effects of the terrain inclination. The larch forest uptake was estimated by means of a two-layer model to separate the understorey uptake from the larch one. Even if the total ozone fluxes were generally high, up to 30–40 nmol O₃ m⁻² s⁻¹ in both years, the stomatal uptake by the larch forest was relatively low (around 15% of the total deposition).Ozone risk was assessed considering the POD₁ received by the larch forest and the exposure index AOT40 estimated with both local data and data from the map obtained by the passive samplers monitoring.
Показать больше [+] Меньше [-]Trimethylamine removal by plant capsule of Sansevieria kirkii in combination with Bacillus cereus EN1 Полный текст
2017
Treesubsuntorn, Chairat | Boraphech, Phattara | Thiravetyan, Paitip
Trimethylamine (TMA) contamination produces a strong “fishy” odor and can cause pathological changes in humans. By screening native microorganisms from Sansevieria kirkii exposed to 100 ppm TMA, it was shown that endophytic bacteria number 1 (EN1) and number 2 (EN2) have a higher TMA tolerance and removal capacity than other bacteria species in a closed system. In addition, EN1 and EN2 demonstrated the ability to produce high quantities of indole-3-acetic acid (IAA) and use 1-aminocyclopropane-1-carboxylic acid (ACC), which is found normally in plant growth-promoting bacteria (PGPB). Moreover, 16S ribosomal DNA (rDNA) sequences of EN1 and EN2 identification showed that EN1 and EN2 was the same bacteria species, Bacillus cereus. B. cereus EN1 was chosen to apply with S. kirkii to remove TMA in a plant capsule, which was compared to control conditions. It was found that 500 g of soil with S. kirkii inoculated with B. cereus EN1 had a higher TMA removal efficiency than other conditions. Moreover, the flow rate of TMA-contaminated gas was varied (0.03–1 L min⁻¹) to calculate the loading rate and elimination capacity. The maximum loading rate of 500 g soil with B. cereus EN1-inoculated S. kirkii was 2500 mg m⁻³ h⁻¹, while other conditions showed only around 250–750 mg m⁻³ h⁻¹. Therefore, a plant capsule with B. cereus EN1-inoculated S. kirkii had the potential to be applied in TMA-contaminated air.
Показать больше [+] Меньше [-]Distribution, sources, and ecological risk assessment of polycyclic aromatic hydrocarbons in surface sediments from the Haihe River, a typical polluted urban river in Northern China Полный текст
2017
Qian, Xiao | Liang, Baocui | Liu, Xuan | Liu, Xinhui | Wang, Juan | Liu, Fei | Cui, Baoshan
The distribution, sources, and ecological risk of polycyclic aromatic hydrocarbons (PAHs) were investigated in surface sediments from the Haihe River. Total PAH concentrations varied from 171.4 to 9511.2 ng g⁻¹ with an average of 2125.4 ng g⁻¹, suggesting serious pollution of the Haihe River in comparison with other reported rivers worldwide. PAH contaminants differed significantly among 17 sampling locations with high values occurring in industrial areas and densely populated areas. The composition of PAHs was characterized by high abundance of 4-ring and 5-ring PAHs, and benzo[a]anthracene, chrysene, and benzo[a]pyrene were the predominant components. Molecular diagnostic ratios have confirmed that PAHs in Haihe River sediments resulted from mixed sources, primarily including various combustion processes. Ecological risk assessment using the Sediments Quality Guidelines indicated that PAHs in sediments could cause certain negative effects on aquatic organisms in most survey regions.
Показать больше [+] Меньше [-]Preparation of La-modified magnetic composite for enhanced adsorptive removal of tetracycline Полный текст
2017
Mi, Xiao | Wang, Mingju | Zhou, Fengyi | Chai, Xiaoqi | Wang, Weiqiang | Zhang, Feifei | Meng, Shanru | Shang, Yaqing | Zhao, Weigao | Li, Guoting
Composite adsorbents usually outperform single component adsorbents as they could combine the properties and advantages of each component. In this research, rare earth element Lanthanum was introduced into magnetic substrate by a method of chemical co-precipitation to enhance its adsorption capability. It was found that the La-modified magnetic composite with a presumed La and Fe₃O₄ molar ratio at 1:50 had a better adsorption performance for tetracycline than the magnetic adsorbents at other molar ratios. The La-modified magnetic composite was characterized by scanning electron microscope, X-ray diffractometer, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy. The results showed that the magnetic adsorbent was nano-sized, and the introduction of La did not change the crystal structure of magnetic substrate. The adsorptive removal of tetracycline was favorable at neutral pH conditions. Kinetic experiments indicated that most of the uptake occurred within the initial 120 min. Chemisorption occurred in the process while rate-determining step might be diffusive in nature. An empirical model (Langmuir model) was applied in this paper, and fitting result indicates that the q ₘₐₓ value of the magnetic composite reached as much as 145.9 mg/g for the uptake of tetracycline at 298 K. The above indicates that method of La doping could significantly enhance the adsorption capability of an intentionally designed composite adsorbent.
Показать больше [+] Меньше [-]Management of agricultural waste for removal of heavy metals from aqueous solution: adsorption behaviors, adsorption mechanisms, environmental protection, and techno-economic analysis Полный текст
2017
Elhafez, S.E Abd | Hamad, H. A. | Zaatout, A. A. | Malash, G. F.
In the last decades, Egypt has been suffering from the phenomenon of black cloud resulting from burning rice husk and increasing the demand for water leading to the water crisis. An alternative, low-value and surplus agricultural byproduct (rice husk, RH) has an enormous potential for the removal of Cu(II) ions from water. The present study focuses on the chance of the use of rice husk as a bio-adsorbent without any chemical treatment instead of burning it and soiling the environment. The elemental, structural, morphological, surface functional, thermal, and textural characteristics of RH are determined by XRF, XRD, SEM, FT-IR, TGA, and BET surface area, respectively, and contributed to the understanding of the adsorption mechanism of Cu(II) ions in aqueous solution. Also, the performance analysis, adsorption mechanism, influencing factors, favorable conditions, etc. are discussed in this article. The results obtained from optimization by batch mode are achieved under the following conditions: initial concentration, 150 ppm; amount of rice husk, 1 g; average particle size, 0.25 mm; temperature, 25 °C; pH, 4; agitation rate, 180 rpm; and contact time, 60 min. RH exhibits a high degree of selectivity for Cu(II) adsorption. The adsorption isotherm is fitted well with Langmuir and Freundlich models with R ² 0.998 and 0.997, respectively. The adsorption is well governed by the pseudo-second-order kinetics. It is observed that the rate of adsorption improves with decreasing temperature, and the process is exothermic and non-spontaneous. Particular attention has being paid to factors as production processes, fixed/operational cost, production cost, and profit. The techno-economical analysis is presented in this study that provides precise demands on capital for a fixed investment, provisions for operational capital, and finally provisions for revenue. The social, economical, and environmental benefits by industrial point of view using low-cost adsorbent are also discussed.
Показать больше [+] Меньше [-]