Affiner votre recherche
Résultats 2691-2700 de 4,033
Evaluating the ameliorative efficacy of Spirulina platensis on spermatogenesis and steroidogenesis in cadmium-intoxicated rats
2016
Farag, Mayada R. | Abd EL-Aziz, R. M. | Ali, H. A. | Ahmed, Sahar A.
The present study was conducted to evaluate the ameliorative efficacy of Spirulina platensis (SP) on reproductive dysfunctions induced by cadmium chloride (CdCl₂) in male rats. Rats (n = 40) were divided into five groups (eight rats/each). Group 1: served as control without any treatment. Group 2: Rats were administered SP (150 mg/kg body weight (BW)) in drinking water for 10 days. Group3: Rats were subcutaneously injected with CdCl₂ (2 mg/kg BW) daily for 10 days. Group 4: Rats were co-treated with both CdCl₂ (2 mg/kg BW) and SP (150 mg/kg BW) daily for 10 days (SP prophylactic group). Group5: Rats received CdCl₂ for 10 days followed by administration of SP alone in drinking water daily for another 30 days with the same mentioned routes and doses (SP treatment group). From our findings, the administration of SP alone or co-administration with Cd significantly attenuated the harmful effects of Cd, suggesting its beneficial role in improving spermatogenesis and steroidogenesis after Cd exposure.
Afficher plus [+] Moins [-]Aqueous chlorination of acebutolol: kinetics, transformation by-products, and mechanism
2016
Khalit, Wan Nor Adira Wan | Tay, Kheng Soo
This study investigated the reaction kinetics and the transformation by-products of acebutolol during aqueous chlorination. Acebutolol is one of the commonly used β-blockers for the treatment of cardiovascular diseases. It has been frequently detected in the aquatic environment. In the kinetics study, the second-order rate constant for the reaction between acebutolol and chlorine (k ₐₚₚ) was determined at 25 ± 0.1 °C. The degradation of acebutolol by free available chlorine was highly pH dependence. When the pH increased from 6 to 8, it was found that the k ₐₚₚ for the reaction between acebutolol and free available chlorine was increased from 1.68 to 11.2 M⁻¹ min⁻¹. By comparing with the reported k ₐₚₚ values, the reactivity of acebutolol toward free available chlorine was found to be higher than atenolol and metoprolol but lower than nadolol and propranolol. Characterization of the transformation by-products formed during the chlorination of acebutolol was carried out using liquid chromatography-quadrupole time-of-flight high-resolution mass spectrometry. Seven major transformation by-products were identified. These transformation by-products were mainly formed through dealkylation, hydroxylation, chlorination, and oxidation reactions.
Afficher plus [+] Moins [-]Changing roles of ammonia-oxidizing bacteria and archaea in a continuously acidifying soil caused by over-fertilization with nitrogen
2016
Song, He | Che, Zhao | Cao, Wenchao | Huang, Ting | Wang, Jingguo | Dong, Zhaorong
Nitrification coupled with nitrate leaching contributes to soil acidification. However, little is known about the effect of soil acidification on nitrification, especially on ammonia oxidation that is the rate-limiting step of nitrification and performed by ammonia-oxidizing bacteria (AOB) and archaea (AOA). Serious soil acidification occurs in Chinese greenhouses due to the overuse of N-fertilizer. In the present study, greenhouse soils with 1, 3, 5, 7, and 9 years of vegetable cultivation showed a consistent pH decline (i.e., 7.0, 6.3, 5.6, 4.9, and 4.3). Across the pH gradient, we analyzed the community structure and abundance of AOB and AOA by pyrosequencing and real-time PCR techniques, respectively. The recovered nitrification potential (RNP) method was used to determine relative contributions of AOA and AOB to nitrification potential. The results revealed that soil acidification shaped the community structures of AOA and AOB. In acidifying soil, soil pH, NH₃ concentration, and DOC content were critical factors shaping ammonia oxidizer community structure. AOB abundance, but not AOA, was strongly influenced by soil acidification. When soil pH was below 5.0, AOA rather than AOB were responsible for almost all of the RNP. However, when soil pH ranged from 5.6 to 7.0, AOB were the major contributors to RNP. The group I.1a-associatied AOA had more relative abundance in low pH (pH<6.3), whereas group I.1b tended to prefer neutral pH. Clusters 2, 10, and 12 in AOB were more abundant in acidic soil (pH <5.6), while Nitrosomonas-like lineage and unclassified lineage 3 were prevailing in neutral soil and slightly acidic soil (pH, 6.0–6.5), respectively. These results suggested that soil acidification had a profound impact on ammonia oxidation and more specific lineages in AOB occupying different pH-associated niches required further investigation.
Afficher plus [+] Moins [-]Cytotoxicity and mutagenicity of sidestream cigarette smoke particulate matter of different particle sizes
2016
Li, Xiang | Lin, Bencheng | Zhang, Huashan | Xie, Fuwei | Ta, Na | Tian, Lei | Liu, Huimin | Xi, Zhuge
Sidestream cigarette smoke, the major component of environmental tobacco smoke, is a complex and reactive aerosol. The particulate matter (PM) in sidestream smoke is one of the carriers of chemical constituents. However, particle size-dependent toxicological effects of PM are poorly understood. In this study, we evaluated the relationship between the PM size and in vitro cytotoxicity and mutagenicity of sidestream cigarette smoke. A NanoMoudi-II™ 125A was used to collect PM samples ranging from 10 nm to 10 μm. The in vitro toxicity of PM was evaluated using a neutral red cytotoxicity assay and Salmonella mutagenicity assay. The results showed that the cytotoxicity and mutagenicity of PM larger than 1 μm was significantly lower than PM sized 10 nm–1 μm. Furthermore, there was a noticeable trend that the smaller the size of the PM of sidestream cigarette smoke, the greater the toxicity. This study suggests that the toxicity of PM in sidestream cigarette smoke is size-dependent.
Afficher plus [+] Moins [-]Determination of personal care products and hormones in leachate and groundwater from Polish MSW landfills by ultrasound-assisted emulsification microextraction and GC-MS
2016
Kapelewska, Justyna | Kotowska, Urszula | Wiśniewska, Katarzyna
Determination of the endocrine disrupting compounds (EDCs) in leachate and groundwater samples from the landfill sites is very important because of the proven harmful effects of these compounds on human and animal organisms. A method combining ultrasound-assisted emulsification microextraction (USAEME) and gas chromatography–mass spectrometry (GC-MS) was developed for simultaneous determination of seven personal care products (PCPs): methylparaben (MP), ethylparaben (EP), propylparaben (PP), buthylparaben (BP), benzophenone (BPh), 3-(4-methylbenzylidene)camphor (4-MBC), N,N-diethyltoluamide (DEET), and two hormones: estrone (E1) and β-estradiol (E2) in landfill leachate and groundwater samples. The limit of detection (LOD)/limit of quantification (LOQ) values in landfill leachate and groundwater samples were in the range of 0.003–0.083/0.009–0.277 μg L⁻¹ and 0.001–0.015/0.002–0.049 μg L⁻¹, respectively. Quantitative recoveries and satisfactory precision were obtained. All studied compounds were found in the landfill leachates from Polish municipal solid waste (MSW) landfills; the concentrations were between 0.66 and 202.42 μg L⁻¹. The concentration of pollutants in groundwater samples was generally below 0.1 μg L⁻¹.
Afficher plus [+] Moins [-]The co-occurrence of the demosponge Hymeniacidon perlevis and the edible mussel Mytilus galloprovincialis as a new tool for bacterial load mitigation in aquaculture
2016
Longo, Caterina | Cardone, Frine | Corriero, Giuseppe | Licciano, Margherita | Pierri, Cataldo | Stabili, Loredana
Pollutants in marine coastal areas are mainly a consequence of anthropogenic inputs, and microorganisms often play a major role in determining the extent of this pollution. Thus, practical and eco-friendly techniques are urgently required in order to control or minimise the pathogenic bacterial problem. The bacterial accumulation of Mytilus galloprovincialis (Lamarck 1919) in the presence or absence of another filter feeder, the demosponge Hymeniacidon perlevis (Montagu 1818) on sewage flowing into the Northern Ionian Sea has been estimated in a laboratory study. On account of the interesting results obtained, we also evaluated the bioremediation capability of the sponges when reared in co-culture with mussels. Specimens of M. galloprovincialis and H. perlevis were collected from the Mar Grande and from the Second Inlet of the Mar Piccolo of Taranto (Northern Ionian Sea, Italy), respectively. In the laboratory, we detected the bacterial abundances in the sewage, in sponge homogenates (both sponges alone and sponges that have been added to sewage with mussels) and in mussel homogenates (both mussels alone and mussels that have been added to sewage with sponges). In the field, we estimated the bacterial concentration in both the seawater within the mussels culture and the seawater collected where mussels were reared in co-culture with sponges. The bacteriological analyses were performed analysing the following parameters: the density of culturable heterotrophic bacteria by spread plate on marine agar, total culturable bacteria at 37 °C on plate count agar and vibrios on thiosulphate–citrate–bile–sucrose–salt (TCBS) agar. Total coliforms, Escherichia coli and intestinal streptococci concentrations were detected by the MPN method. The study demonstrates a higher efficiency of the sponges in removing all the considered bacterial groups compared to the mussels. Due to the conspicuous bacterial accumulation by the sponge, we can conclude that the co-occurrence of the filter-feeder H. perlevis with M. galloprovincialis is a powerful tool in reducing the bacterial load in shellfish culture areas thus playing a role in mitigating the health hazard related to the consumption of edible mussels.
Afficher plus [+] Moins [-]Experimental and numerical characterization of floc morphology: role of changing hydraulic retention time under flocculation mechanisms
2016
Nan, Jun | Yao, Meng | Chen, Ting | Wang, Zhenbei | Li, Qinggui | Zhan, Dan
The formation, breakage, and re-growth of flocs were investigated by using modified flocculation tests and numerical simulation to explore the evolution of floc morphology for different hydraulic retention times. The shorter the aggregation time was, the smaller the flocs produced for the same hydraulic conditions were. Another interesting discovery was that broken flocs that formed in shorter aggregation time had the capacity to completely recover, whereas those formed in a longer amount of time had rather worse reversibility of broken flocs. With the addition of the maximum motion step in the representative two-dimensional diffusion-limited aggregation (DLA) model, there was a transition for flocs from isotropic to anisotropic as the maximum motion step increased. The strength of flocs was mainly affected by the distribution of particles near the aggregated core rather than distant particles. A simplified breakage model, which found that broken flocs provided more chances for diffused particles to access the inner parts of flocs and to be uniformly packed around the aggregated core, was first proposed. Moreover, an important result showed that the floc fragments formed with a larger value of the maximum motion step had more growing sites than did those with a smaller msa value, which was a benefit of following the re-forming procedure.
Afficher plus [+] Moins [-]Multistress effects on goldfish (Carassius auratus) behavior and metabolism
2016
Gandar, Allison | Jean, Séverine | Canal, Julie | Marty-Gasset, Nathalie | Gilbert, Franck | Laffaille, Pascal
Crossed effects between climate change and chemical pollutions were identified on community structure and ecosystem functioning. Temperature rising affects the toxic properties of pollutants and the sensitiveness of organisms to chemicals stress. Inversely, chemical exposure may decrease the capacity of organisms to respond to environmental changes. The aim of our study was to assess the individual and crossed effects of temperature rising and pesticide contamination on fish. Goldfish, Carassius auratus, were exposed during 96 h at two temperatures (22 and 32 °C) to a mixture of common pesticides (S-metolachlor, isoproturon, linuron, atrazine-desethyl, aclonifen, pendimethalin, and tebuconazol) at two environmentally relevant concentrations (total concentrations MIX1 = 8.4 μg L⁻¹ and MIX2 = 42 μg L⁻¹). We investigated the sediment reworking behavior, which has a major ecological functional role. We also focused on three physiological traits from the cellular up to the whole individual level showing metabolic status of fish (protein concentration in liver and muscle, hepatosomatic index, and Fulton’s condition factor). Individual thermal stress and low concentrations of pesticides decreased the sediment reworking activity of fish and entrained metabolic compensation with global depletion in energy stores. We found that combined chemical and thermal stresses impaired the capacity of fish to set up an efficient adaptive response. Our results strongly suggest that temperature will make fish more sensitive to water contamination by pesticides, raising concerns about wild fish conservation submitted to global changes.
Afficher plus [+] Moins [-]Effective utilization of distiller’s grain soluble—an agro-industrial waste in the feed of cage-reared minor carp Labeo bata in a tropical reservoir, India
2016
Hassan, M. A. | Aftabuddin, Md | Meena, D. K. | Mishal, P. | Das Gupta, S.
A 60-day feeding trial was conducted to evaluate the efficacy of distiller’s grain soluble (brewery waste) as a prospective ingredient to substitute expensive and high demand feed component, soybean meal for farming Labeo bata in cages installed in tropical reservoir. Two isonitrogenous and isocaloric diets comprising brewery waste (49.2 % CP) as test diet and soybean meal (44.4 % CP) as reference diet were formulated and extruded to obtain 2-mm floating pellets. The efficacy of the diets was tested in terms of survival (%), live weight gain (%), SGR (%/day), FCR, PER and ANPU and recorded 65 ± 0.2, 96 ± 8.1, 1.9 ± 0.1, 2.5 ± 0.02, 1.4 ± 0.1, 20.3 ± 2.0 and 66 ± 0.6, 112 ± 9.8, 2.2 ± 0.1, 2.2 ± 0.2, 1.6 ± 0.1 and 20 ± 2.1, respectively, for soybean and brewer’s waste-based formulated feed. The analyses of results revealed that survival, growth parameters and biochemical composition of whole body tissue did not differ significantly (p > 0.05) despite complete replacement of soybean meal by brewery waste. However, the cost estimate of diet revealed marked reduction of feed cost of Rs. 9.2/kg (33.8 %) in the test diet as compared to the reference diet. The study suggests that brewery waste could effectively replace soybean meal without effecting survival and growth of the fish. The finding thus may pave a productive way for reducing environmental pressure of disposal of an agro-industrial waste.
Afficher plus [+] Moins [-]Distribution of butyltin compounds in Brazil’s southern and southeastern estuarine ecosystems: assessment of spatial scale and compartments
2016
dos Santos, Dayana Moscardi | Turra, Alexander | de Marchi, Mary Rosa Rodrigues | Montone, Rosalinda Carmela
Butyltin compounds (BTs), including tributyltin (TBT) and its degradation products, dibutyltin and monobutyltin, have been found in a diversity of aquatic systems and causing toxic effects in target and nontarget organisms. They enter in coastal systems through different sources (as antifouling paints, industrial effluents, etc.) where they interact with biotic and abiotic components, and their distribution is commonly determined by the morphological and hydrodynamic conditions of the coastal systems. In this study, we discuss the contamination by BTs on a spatial scale (eight estuaries with three subareas each) and in different compartments of the estuaries (sediments, suspended particulate matter (SPM), and estuarine catfish tissues (liver and gills). Lower concentrations of BTs were found in the sediments (n.d. to 338 ng g⁻¹) in comparison to studies before a ban of TBT in antifouling paints was enacted, mostly indicating an old input or preservation related with sediment properties and composition. For SPM samples (n.d. to 175 ng L⁻¹) as well as in fish tissues (n.d. to 1426 ng g⁻¹), the presence of these compounds was frequent, especially in the fish due to their movement throughout the estuaries and the potential to assess point sources of BTs. These results indicate that BTs persist in the environment, with variation in amounts between investigated estuaries and even at locations inside the same estuary, because of ideal preservation conditions, transport to remote areas, and input from different sources.
Afficher plus [+] Moins [-]