Lipid organization regulates annexin A2 Ca2 +-sensitivity for membrane bridging and its modulator effects on membrane fluidity

Annexin A2 (AnxA2) is a phospholipid binding protein that has been implicated in many membrane-related cellular functions. AnxA2 is able to bind different acidic phospholipids such as phosphatidylserine (PS) and phosphatidylinositol-4,5-bisphosphate (PI2P). This binding is mediated by Ca^2 +-dependent and Ca^2 +-independent mechanisms. The specific functions of annexin A2 related to these two phospholipids and the molecular mechanisms involved in their interaction remain obscure. Herein we studied the influence of lipid composition on the Ca^2 +-dependency of AnxA2-mediated membrane bridging and on membrane fluidity. Membrane models of ten different lipid compositions and detergent-resistant membranes from two cellular sources were investigated. The results show that the AnxA2-mediated membrane bridging requires 3 to 50 times less calcium for PS-membranes than for PI2P-membranes. Membrane fluidity was measured by the ratiometric fluorescence parameter generalized polarization method with two fluorescent probes. Compared to controls containing low phospholipid ligand, AnxA2 was found to reduce the membrane fluidity of PI2P-membranes twice as much as the PS-membranes in the presence of calcium. On the contrary, at mild acidic pH in the absence of calcium AnxA2 reduces the fluidity of the PS-membranes more than the PI2P-membranes. The presence of cholesterol on the bilayer reduced the AnxA2 capacity to reduce membrane fluidity. The presented data shed light on the specific roles of PI2P, PS and cholesterol present on membranes related to the action of annexin A2 as a membrane bridging molecule during exocytosis and endocytosis events and as a plasma membrane domain phospholipid packing regulator.     

Lateral diffusion of bilayer lipids measured via 31P CODEX NMR

We have employed ³¹P CODEX (centre-band-only-detection-of-exchange) NMR to measure lateral diffusion coefficients of phospholipids in unilamellar lipid bilayer vesicles consisting of 1-palmitoyl-2-oleoyl-phosphatidylcholine (POPC), alone or in mixtures with 30 mol% 1-palmitoyl-2-oleoyl-phosphatidylglycerol (POPG) or cholesterol (CHOL). The lateral diffusion coefficients of POPC and POPG were extracted from experimental CODEX signal decays as a function of increasing mixing time, after accounting for the vesicle's size and size distribution, as determined via dynamic light scattering, and the viscosity of the vesicular suspension, as determined via ¹H pulsed field gradient NMR. Lateral diffusion coefficients for POPC and POPG determined in this fashion fell in the range 1.0–3.2 × 10^?12 m² s^?1 at 10 °C, depending on the vesicular composition, in good agreement with accepted values. Thus, two advantages of ³¹P CODEX NMR for phospholipid lateral diffusion measurements are demonstrated: no labelling of the molecule of interest is necessary, and multiple lateral diffusion coefficients can be measured simultaneously. It is expected that this approach will prove particularly useful in diagnosing heterogeneities in lateral diffusion behaviours, such as might be expected for specific lipid–lipid or lipid–protein interactions, and thermotropic or electrostatically induced phase inhomogeneities.     

Design,synthesis, and DNA binding characteristics of a group of orthogonally positioned diamino,N-formamido,pyrrole- and imidazole-containing polyamides

Orthogonally positioned diamino/dicationic polyamides (PAs) have good water solubility and enhanced binding affinity, whilst retaining DNA minor groove and sequence specificity compared to their monoamino/monocationic counterparts. The synthesis and DNA binding properties of the following diamino PAs: f-IPI (3a), f-IPP (4), f-PIP (5), and f-PPP (6) are described. P denotes the site where a 1-propylamino group is attached to the N1-position of the heterocycle. Binding of the diamino PAs to DNA was assessed by DNase I footprinting, thermal denaturation, circular dichroism titration, biosensor surface plasmon resonance (SPR), and isothermal titration calorimetry (ITC) studies. According to SPR studies, f-IPI (3a) bound more strongly (K_eq = 2.4 × 10⁸ M^?1) and with comparable sequence selectivity to its cognate sequence 5′-ACGCGT-3′ when compared to its monoamino analog f-IPI (1). The binding of f-IPI (3a) to 5′-ACGCGT-3′ via the stacked dimer motif was balanced between enthalpy and entropy, and that was quite different from the enthalpy-driven binding of its monoamino parent f-IPI (1). f-IPP (4) also bound more strongly to its cognate sequence 5′-ATGCAT-3′ (K_eq = 7.4 × 10⁶ M^?1) via the side-by-side stacked motif than its monoamino analog f-IPP (2a). Although f-PPP (6) bound via a 1:1 motif, it bound strongly to its cognate sequence 5′-AAATTT-3′ (K_eq = 4.8 × 10⁷ M^?1), 15-times higher than the binding of its monoamino analog f-PPP (2c), albeit f-PPP bound via the stacked motif. Finally, f-PIP (5) bound to its target sequence 5′-ATCGAT-3′ as a stacked dimer and it has the lowest affinity among the diamino PAs tested (K_eq <1 × 10⁵ M^?1). This was about two times lower in affinity than the binding of its monoamino analog f-PIP (2b). The results further demonstrated that the ‘core rules’ of DNA recognition by monoamino PAs also apply to their diamino analogs. Specifically, PAs that contain a stacked IP core structure bind most strongly (highest binding constants) to their cognate GC doublet, followed by the binding of PAs with a stacked PP structure to two degenerate AT base pairs, and finally the binding of PAs with a PI core to their cognate CG doublet.     

Nitrate removal and greenhouse gas production in a stream-bed denitrifying bioreactor

Denitrifying bioreactors are currently being tested as an option for treating nitrate (NO₃^?) contamination in groundwater and surface waters. However, a possible side effect of this technology is the production of greenhouse gases (GHG) including nitrous oxide (N₂O) and methane (CH₄). This study examines NO₃^? removal and GHG production in a stream-bed denitrifying bioreactor currently operating in Southern Ontario, Canada. The reactor contains organic carbon material (pine woodchips) intended to promote denitrification. Over a 1 year period, monthly averaged removal of influent (stream water) NO₃^? ranged from 18 to 100% (0.3–2.5 mg N L^?1). Concomitantly, reactor dissolved N₂O and CH₄ production, averaged 6.4 μg N L^?1 (2.4 mg N m^?2 d^?1), and 974 μg C L^?1 (297 mg C m^?2 d^?1) respectively, where production is calculated as the difference between inflow and effluent concentrations. Gas bubbles entrapped in sediments overlying the reactor had a composition ranging from 19 to 64% CH₄, 1 to 6% CO₂, and 0.5 to 2 ppmv N₂O; however, gas bubble emission rates were not quantified in this study. Dissolved N₂O production rates from the bioreactor were similar to emission rates reported for some agricultural croplands (e.g. 0.1–15 mg N m^?2 d^?1) and remained less than the highest rates observed in some N-polluted streams and rivers (e.g. 110 mg N m^?2 d^?1, Grand R., ON). Dissolved N₂O production represented only a small fraction (0.6%) of the observed NO₃^? removal over the monitoring period. Dissolved CH₄ production during summer months (up to 1236 mg C m^?2 d^?1), was higher than reported for some rivers and reservoirs (e.g. 6–66 mg C m^?2 d^?1) but remained lower than rates reported for some wastewater treatment facilities (e.g. sewage treatment plants and constructed wetlands, 19,500–38,000 mg C m^?2 d^?1).     

Synthesis of perylene bisimide-centered glycodendrimer and its interactions with concanavalin A

A novel glycodendrimer based on 18 peripheral α-d-mannoses functionalized perylene bisimide derivative PBI-18-Man was synthesized and its selectively binding interactions for Con A were investigated by CD spectra and turbidity assay, which exhibited strong binding affinity for Con A with the binding constant of 1.3 × 10⁸ M^?1 (7.2 × 10⁶ M^?1 for monomeric mannose, valency corrected), 3 orders of magnitude higher affinity than the monovalent mannose ligand. Furthermore, the inhibitory activity for Con A was studied by ELLA experiment, showed 2 times inhibitor activity than the reference compound (α-MMP).     

An insight to the binding of ellagic acid with human serum albumin using spectroscopic and isothermal calorimetry studies

Ellagic acid (EA), a natural polyphenol evidence several pharmacological benefits. The binding profile of EA with human serum albumin (HSA) has been explored and investigated by Isothermal titration calorimetry (ITC), circular dichroism (CD) spectroscopy, time-correlated single-photon counting (TCSPC), absorbance spectroscopy, steady-state fluorescence spectroscopy, and modelling studies. The ITC data analysis revealed the binding Constant (K_a), ΔH, ΔS and ΔG values to be 15.5×10⁴M^?1, ?116.2±18.1 Kcal mol^?1, ?366 cal mol^?1K^?1 and ?7.13 Kcal mol^?1 respectively with a unique binding site at HSA. EA effectively quenched the intrinsic fluorescence of HSA by static quenching, whereas TCSPC data also revealed association of dynamic quenching also. Thermodynamic analysis confirmed that hydrophobic and mainly hydrogen bonding interaction played important role in stabilizing the HSA-EA complex. It further dictates the binding reaction to be enthalpy driven. The secondary structure of HSA was altered upon binding with EA. CD spectroscopic data indicated the fraction of alpha helicity to be decreased from 52% to 40% upon binding to EA. This study will provide an insight on evaluation of this bioactive interaction during transport and releasing efficiency at the target site in human physiological system since HSA is the most important carrier protein in blood serum.     

Molecular dynamics simulation of cation–phospholipid clustering in phospholipid bilayers: Possible role in stalk formation during membrane fusion

In this study, we performed all-atom long-timescale molecular dynamics simulations of phospholipid bilayers incorporating three different proportions of negatively charged lipids in the presence of K⁺, Mg^2 +, and Ca^2 + ions to systemically determine how membrane properties are affected by cations and lipid compositions. Our simulations revealed that the binding affinity of Ca^2 + ions with lipids is significantly stronger than that of K⁺ and Mg^2 + ions, regardless of the composition of the lipid bilayer. The binding of Ca^2 + ions to the lipids resulted in bilayers having smaller lateral areas, greater thicknesses, greater order, and slower rotation of their lipid head groups, relative to those of corresponding K⁺- and Mg^2 +-containing systems. The Ca^2 + ions bind preferentially to the phosphate groups of the lipids. The complexes formed between the cations and the lipids further assembled to form various multiple-cation-centered clusters in the presence of anionic lipids and at higher ionic strength—most notably for Ca^2 +. The formation of cation–lipid complexes and clusters dehydrated and neutralized the anionic lipids, creating a more-hydrophobic environment suitable for membrane aggregation. We propose that the formation of Ca^2 +–phospholipid clusters across apposed lipid bilayers can work as a “cation glue” to adhere apposed membranes together, providing an adequate configuration for stalk formation during membrane fusion.     

Treatment of dye (Remazol Blue) and heavy metals using yeast cells with the purpose of managing polluted textile wastewaters

The bioaccumulation of chromium(VI), nickel(II), copper(II), and reactive dye by the yeast Rhodotorula mucilaginosa has been investigated in media containing molasses as a carbon and energy source. Optimal pH values for the yeast cells to remove the pollutants were pH 4 for copper(II) and dye, pH 6 for chromium(VI) and dye, and pH 5 for nickel(II) and dye in media containing 50 mg l^?1 heavy metal and 50 mg l^?1 Remazol Blue. The maximum dye bioaccumulation was observed within 4–6 days and uptake yields varied from 93% to 97%. The highest copper(II) removal yields measured were 30.6% for 45.4 mg l^?1 and 32.4% for 95.9 mg l^?1 initial copper(II) concentrations. The nickel(II) removal yield was 45.5% for 22.3 mg l^?1, 38.0% for 34.7 mg l^?1, and 30.3% for 62.2 mg l^?1. Higher chromium(VI) removal yields were obtained, such as 94.5% for 49.2 mg l^?1 and 87.7% for 129.2 mg l^?1 initial chromium(VI) concentration. The maximum dye and heavy metal bioaccumulation yield was investigated in media with a constant dye (approximately 50 mg l^?1) and increasing heavy metal concentration. In the medium with 48.9–98.8 mg l^?1 copper(II) and constant dye concentration, the maximum copper(II) bioaccumulation was 27.7% and 27.9% whereas the maximum dye bioaccumulation was 96.1% and 95.3%. The maximum chromium(VI) bioaccumulation in the medium with dye was 95.2% and 80.3% at 48.2 and 102.2 mg l^?1 chromium(VI) concentrations. In these media dye bioaccumulation was 76.1% and 35.1%, respectively. The highest nickel(II) removal was 6.1%, 20.3% and 16.0% in the medium with 23.8 mg l^?1 nickel(II) + 37.8 mg l^?1 dye, 38.1 mg l^?1 nickel(II) + 33.4 mg l^?1 dye and 59.0 mg l^?1 nickel(II) + 39.2 mg l^?1 dye, respectively. The maximum dye bioaccumulation yield in the media with nickel(II) was 94.1%, 78.0% and 58.7%, respectively.     

Chronic cigarette smoking alters erythrocyte membrane lipid composition and properties in male human volunteers

Cigarette smoking is a major lifestyle factor influencing the health of human beings. The present study investigates smoking induced alterations on the erythrocyte membrane lipid composition, fluidity and the role of nitric oxide. Thirty experimental and control subjects (age 35 ± 8) were selected for the study. Experimental subjects smoke 12 ± 2 cigarettes per day for 7–10 years. In smokers elevated nitrite/nitrate levels in plasma and red cell lysates were observed. Smokers showed increased hemolysis, erythrocyte membrane lipid peroxidation, protein carbonyls, C/P ratio (cholesterol and phospholipid ratio), anisotropic (γ) value with decreased Na⁺/K⁺-ATPase activity and sulfhydryl groups. Alterations in smokers erythrocyte membrane individual phospholipids were also evident from the study. Red cell lysate nitric oxide positively correlated with C/P ratio (r = 0.565) and fluorescent anisotropic (γ) value (r = 0.386) in smokers. Smoking induced generation of reactive oxygen/nitrogen species might have altered erythrocyte membrane physico-chemical properties.     

Inhibitory effects of taurine and oat fiber on intestinal endotoxin release in rats

Numerous studies have demonstrated that endotoxin plays an important role in the development and progression of hepatic cirrhosis. However, there is no effective remedy for the prevention and treatment of intestinal endotoxemia. Taurine has been reported to have beneficial effects on endotoxemia. Oats have been shown to absorb intestinal toxins and increase excretion of intestinal toxins. The present study was to investigate whether a combination of taurine and oat has an additive inhibitory effect on endotoxin release in a rat liver ischemia/reperfusion model. Our results showed that the combination of taurine (300 mg kg^?1 d^?1) and oat fiber (15 g kg^?1 d^?1) significantly reduced endotoxin levels in the portal vein by 36.3% when compared to the control group (0.168 ± 0.035 Eu/ml in the treatment group vs 0.264 ± 0.058 Eu/ml in the control group, P < 0.01). The treatment of taurine (300 mg kg^?1 d^?1) and oat fiber (15 g kg^?1 d^?1) induced 21.5% and 18.4% reduction in endotoxin levels, respectively, when compared to the control group (P < 0.05). We conclude that the combination of taurine and oat fiber achieved an additive inhibitory effect on intestinal endotoxin release, which might be an effective approach for the treatment of intestinal endotoxemia.     

Direct in vivo interaction of the antibiotic primycin with the plasma membrane of Candida albicans: An EPR study

The direct interaction of the antibiotic primycin with the plasma membrane was investigated by employing the well-characterized ergosterol-producing, amphotericin B-sensitive parental Candida albicans strain 33erg⁺ and its ergosterol-less amphotericin B-resistant plasma membrane mutant erg-2. The growth inhibition concentration in shaken liquid medium was 64 μg ml^?1 for 33erg⁺ and 128 μg ml^?1 for erg-2, suggesting that the plasma membrane composition influences the mode of action of primycin. To determine the primycin-induced changes in the plasma membrane dynamic, electron paramagnetic resonance (EPR) spectroscopy methods were used, the spin-labeled fatty acid 5-(4,4-dimethyloxazolidine-N-oxyl)stearic acid) being applied for the in vivo measurements. The phase transition temperatures of untreated strain 33erg⁺ and its mutant erg-2 were 12.5 °C and 11 °C, respectively. After 128 μg ml^?1 primycin treatment, these values increased to 17.5 °C and 16 °C, revealing a significant reduction in the phospholipid flexibility. Saturation transfer EPR measurements demonstrated that, the rotational correlation times of the spin label molecule for the control samples of 33erg⁺ and erg-2 were 60 ns and 100 ns. These correlation times gradually decreased on the addition of increasing primycin concentrations, reaching 8 μs and 1 μs. The results indicate the plasma membrane “rigidizing” effect of primycin, a feature that may stem from its ability to undergo complex formation with membrane constituent fatty acid molecules, causing alterations in the structures of phospholipids in the hydrophobic surface near the fatty acid chain region.     

Structure and seasonal dynamics of the protozoan community (heterotrophic flagellates,ciliates, amoeboid protozoa) in the plankton of a large river (River Danube,Hungary)

Seasonal dynamics of all major protozoan groups were investigated in the plankton of the River Danube, upstream of Budapest (Hungary), by bi-weekly sampling over a 1-year long period. Sixty-one heterotrophic flagellate, 14 naked amoeba, 50 testate amoeba, 4 heliozoan and 83 ciliate morphospecies were identified. The estimated abundance ranges of major groups throughout the year were as follows: heterotrophic flagellates, 0.27–7.8×10⁶ ind. l^?1; naked amoebae, max. 3300 ind. l^?1; testaceans, max. 1600 ind. l^?1; heliozoans, max. 8500 ind. l^?1; ciliates, 132–34,000 ind. l^?1. In terms of biovolume, heterotrophic flagellates dominated throughout the year (max. 0.58 mm³ l^?1), and ciliates only exceeded their biovolume in summer (max. 0.76 mm³ l^?1). Naked amoeba and heliozoan biovolume was about one, and testacean biovolume 1–3, orders of magnitude lower than that of ciliates. In winter, flagellates, mainly chrysomonads, had the highest biomass, whilst ciliates were dominated by peritrichs. In 2005 from April to July a long spring/summer peak occurred for all protozoan groups. Beside chrysomonads typical flagellates were choanoflagellates, bicosoecids and abundant microflagellates (large chrysomonads and Collodictyon). Most abundant ciliates were oligotrichs, while Phascolodon, Urotricha, Vorticella, haptorids, Suctoria, Climacostomum and Stokesia also contributed significantly to biovolume during rapid succession processes. In October and November a second high protozoan peak occurred, with flagellate dominance, and slightly different taxonomic composition.     

Influence of environmental related concentrations of heavy metals on motility parameters and antioxidant responses in sturgeon sperm

The effects of heavy metals (Cd, Cr and Cd + Cr) on the motility parameters and oxidative stress of sterlet (Acipenser ruthenus) sperm were investigated in vitro. Sturgeon sperm were exposed for 2 h to heavy metals at environmental related concentrations (0.1 mg L^?1 Cr, 0.001 mg L^?1 Cd, 0.1 mg L^?1 Cr + 0.001 mg L^?1 Cd) and higher concentrations (5.0 mg L^?1 Cr, 0.05 mg L^?1 Cd, 5.0 mg L^?1 Cr + 0.05 mg L^?1 Cd). Results revealed that environmental concentrations of heavy metals had no significant influence on motility parameters and antioxidant responses indices in sturgeon sperm, except for LPO level and SOD activity. But higher concentrations of these metals induced oxidative tress in sturgeon sperm in vitro, associated with sperm motility parameters inhibition. Our results suggest that using of sperm in vitro assays may provide a novel and efficiently means for evaluating the effects of residual heavy metals in aquatic environment on sturgeon.     

Nitrate removal and hydraulic performance of organic carbon for use in denitrification beds

Denitrification beds are a cost-effective technology for removing nitrate from point source discharge. To date, field trials and operational beds have primarily used wood media as the carbon source; however, the use of alternative more labile carbon media could provide for increased removal rate, lower installation costs and reduced bed size. While previous laboratory experiments have investigated the potential of alternative carbon sources, these studies were typically of short duration and small scale and did not necessarily provide reliable information for denitrification bed design purposes. To address this issue, we compared nitrate removal, hydraulic and nutrient leaching characteristics of nine different carbon substrates in 0.2 m³ barrels, at 14 and 23.5 °C over a 23-month period. Mean nitrate removal rates for the period 10–23 months were 19.8 and 15 g N m^?3 d^?1 (maize cobs), 7.8 and 10.5 g N m^?3 d^?1 (green waste), 5.8 and 7.8 g N m^?3 d^?1 (wheat straw), 3.0 and 4.9 g N m^?3 d^?1 (softwood), and 3.3 and 4.4 g N m^?3 d^?1 (hardwood) for the 14 and 23.5 °C treatments, respectively. Maize cobs provided a 3–6.5-fold increase in nitrate removal over wood media, without prohibitive decrease in hydraulic conductivity, but had higher rates of nutrient leaching at start-up. Significant difference in removal rate occurred between the 14 and 23.5 °C treatments, with the mean Q₁₀ temperature coefficient = 1.6 for all media types in the period 10–23 months.     

Solids hydrolysis and accumulation in a hybrid anaerobic digester-constructed wetlands system

The properties and behaviour of solids retained in a pilot plant constituted of an up-flow anaerobic sludge blanket (UASB) reactor and two constructed wetlands (CWs) were monitored over a 3-year period. The UASB (25.5 m³) was fed with raw municipal wastewater at a flow rate of 61–112 m³ d^?1 and a volumetric loading rate (VLR) of 0.75–1.70 kg TCOD m^?3 d^?1. The CWs (75 m² each) were operated in series and received a fraction (17–20 m³ d^?1) of the UASB effluent. The applied surface loading rates (SLR) were in the range of 3800–8700 g TCOD m^?2 d^?1 (UASB) and 11–15 g BOD₅ m^?2 d^?1 (CWs). The overall system removed 95% TSS, 85% TCOD and 87% BOD₅ on average. For influent VSS, the UASB removed 72.1% and gave a hydrolysis of 63.5%, while the average surplus sludge generation was 8.7%. Over the 3-year period, TSS and VSS accumulated in the CWs at rates of 1.07 and 0.56 kg m^?2 year^?1, respectively. The aerobic biodegradability of the accumulated solids ranged from 23 to 92 mg O₂ g VSS^?1 d^?1 and increased downstream in the CWs. About 59% of the VSS that entered the CWs was removed by hydrolysis, while 24% accumulated on granular media. These low solids accumulation rates were especially remarkable considering the high COD and BOD₅ loading rates applied. The system lay-out appear to be promising in terms of preventing clogging.     

Nitrification rates of algal–bacterial biofilms in wastewater stabilization ponds under light and dark conditions

The objective of this study was to investigate nitrification rates in algal–bacterial biofilms of waste stabilization ponds (WSP) under different conditions of light, oxygen and pH. Biofilms were grown on wooden plates of 6.0 cm by 8.0 cm by 0.4 cm in a PVC tray continuously fed with synthetic wastewater with initial NH₄-N and Chemical Oxygen Demand (COD) concentrations of 40 mg l^?1 and 100 mg l^?1, respectively, under light intensity of 85–95 μE m^?2 s^?1. Batch activity tests were carried out by exposure of the plates to light conditions as above (to simulate day time), dim light of 1.8–2.2 μE m^?2 s^?1 (to simulate reduced light as in deeper locations in WSP) and dark conditions (to simulate night time). Dissolved oxygen (DO) concentration and pH were controlled. At some experiments, both parameters were kept constant, and at others they were left to vary as in WSP. Results show biofilm nitrification rates of 945–1817 mg-N m^?2 d^?1 and 1124–1615 mg-N m^?2 d^?1 for light and dark experiments. When the minimum DO was 4.1 mg l^?1, the biofilm nitrification rates under light and dark conditions did not differ significantly at 95% confidence. When the minimum DO in the dim light experiment was 3.2 mg l^?1, the nitrification rates under light and dim light conditions were 945 mg-N m^?2 d^?1 and 563 mg-N m^?2 d^?1 and these significantly differed. Further decrease of DO to 1.1 mg l^?1 under dark conditions resulted in more decrease of the nitrification rates to 156 mg-N m^?2 d^?1. It therefore seems that under these experimental conditions, biofilm nitrification rates are significantly reduced at a certain point when bulk water DO is between 3.2 mg l^?1 and 4.1 mg l^?1. As long as bulk water DO under dark is high, light is not important in influencing the process of nitrification.     

Effect of enzymatic and hydrothermal treatments of rapeseeds on quality of the pressed rapeseed oils: Part I: Antioxidant capacity and antioxidant content

Response surface methodology was used to evaluate the quantitative effects of three independent variables: rapeseed moisture content, concentration of the added enzymes and conditioning temperature, on the antioxidant capacity and total phenolic, tocopherol, and phospholipid contents in the enzyme-treated rapeseed oils. The highest antioxidant capacity (1220.0, 964.8 μmol TE/100 g) total phenolic (83.3, 74.0 mg SA/100 g) and phospholipid (12,532, 12,376 mg/kg) contents reveal two rapeseed oils extruded from seeds contained 11% moisture, treated with cellulolytic and pectolytic enzymes (0.05%), respectively, and heated at 120 °C. However, the highest content of total tocopherols was determined in rapeseed oils pressed from seeds with 7% moisture, after addition of cellulolytic (0.05%) and pectolytic (0.1%) enzymes, heated at 90 and 105 °C, respectively. Total phenolic and phospholipid contents in the enzyme-treated rapeseed oils correlated significantly (p < 0.0000001) with antioxidant capacities of oils (R² = 0.8710 and 0.6581, respectively). Experimental results of the antioxidant capacity, total phenolic, tocopherol and phospholipid contents were close to the predicted values calculated from the polynomial response surface models equations (R² = 0.9727, 0.9870, 0.8390 and 0.9706 for the cellulolytic enzyme-assisted rapeseed oils and R² = 0.9148, 0.9489, 0.9426 and 0.9479 for the pectolytic enzyme-assisted rapeseed oils). The optimum rapeseed moisture content, enzyme concentration and conditioning temperature for the cellulolytic and pectolytic enzyme-treated rapeseed oils were 11% and 9.7%, 0.08% and 0.1%, and 120 °C, respectively.     

Toward scrubbing the bay: Nutrient removal using small algal turf scrubbers on Chesapeake Bay tributaries

Restoration of the Chesapeake Bay poses significant challenges because of increasing population pressure, conversion of farmland to urban/suburban development, and the expense of infrastructure needed to achieve significant and sustained nutrient reductions from agricultural and urban sources. One radical approach for removing non-point source nutrients before they reach the bay is to deploy large-scale algal turf scrubbers along its tributaries. The objective of this study was to determine rates of nutrient removal and algal fatty acid production using small ATS units located along three Chesapeake Bay rivers. Small-scale ATS units (each containing 1 m² growing area) were operated for 5–10 months from April 2007 to April 2008 on three western shore tributaries of the Chesapeake Bay in Maryland: the Bush River, the Patapsco River and the Patuxent River. Total nitrogen (TN) and total phosphorus (TP) removal rates at the Patuxent site fluctuated considerably but averaged 250 mg TN, 45 mg TP m^?2 day^?1 from May to October 2007, then decreased to 16 mg TN, 3 mg TP m^?2 day^?1 from December 2007 to February 2008. Nutrient removal rates at the Bush river site also fluctuated but averaged only 85 mg TN, 10 mg TP m^?2 day^?1 from May to June 2007, before decreasing to <10 mg TN, <1 mg TP m^?2 day^?1 from July to September 2007. The Patapsco River unit began operation in August 2007, reached its maximum removal values of 150 mg TN, 18 mg TP m^?2 day^?1 from mid-October to late-November 2007, then decreased to values of 45 mg TN, 4 mg TP m^?2 day^?1 from November 15, 2007 to mid-April 2008. In the best case (Patuxent site from May to October 2007), daily removal rates of 250 mg N and 45 mg P m^?2 are equivalent to removal rates of 380 kg N and 70 kg P ha^?1 over a 150-day season in Maryland. Fatty acid (FA) content of the harvested material was consistently low (0.3–0.6% of dry weight) and varied little between sites. Mean algal FA production rates (23–54 mg FA m^?2 day^?1) are equivalent to rates of 34–81 kg FA ha^?1 year^?1 based on a 150-day operational season in Maryland.     

Nutrient uptake and release in ponds under long-term and short-term lotus (Nelumbo nucifera) cultivation: Influence of compost application

Uptake and release of nutrients from ponds used for lotus cultivation were measured in ponds under short-term (1 yr) cultivation with compost application (pond I) and under long-term (20 yr) cultivation without compost application (pond II). Total inflow loads of TN (irrigation water, rainfall and compost) during lotus cultivation period in ponds I and II were 72.3 and 34.3 kg ha^?1 182 day^?1, respectively. TN removal rates in ponds I and II were 77.3 and 49.8% of total inflow load, respectively. Major removal mechanisms of TN were attributed to microbial processes and uptake by lotus. The total outflow loads (infiltration and runoff) of TN during the lotus cultivation period were 13.9 kg ha^?1 182 day^?1 (19.2% of total inflow TN load) for pond I, and 11.3 kg ha^?1 182 day^?1 (32.9% of total inflow TN load) for pond II. For TP the total inflow loads (irrigation water, rainfall and compost) during lotus cultivation in ponds I and II were 80.8 and 1.9 kg ha^?1 182 day^?1, respectively. TP removal rates in ponds I and II were 84.9 and ?274.1% of total input, respectively. Phosphorus removal was attributed to lotus uptake and soil adsorption. The total outflow loads (infiltration and runoff) of TP during lotus cultivation period were 10.1 kg ha^?1 182 day^?1 (12.5% of total inflow TP load) for pond I, and 6.6 kg ha^?1 182 day^?1 (355.6% of total inflow TP load) for pond II. TN and TP in runoff from pond I (with compost) was higher than that in pond II (without compost), showing that TN and TP in runoff were strongly influenced by compost addition. Therefore, in order to satisfy established water-quality standards, the amount of compost used in lotus cultivation should be evaluated.     

Development of biosensor for phenolic compounds containing PPO in β-cyclodextrin modified support and iridium nanoparticles

A biosensor based on the iridium nanoparticles dispersed in ionic liquid (IL) 1-butyl-3-methylimidazolium hexafluorophosphate (Ir-BMI·PF₆) and a celery (Apium graveolens) extract as a source of polyphenol oxidase (PPO) was constructed. A modified support based on β-cyclodextrin (β-CDEP) was used for enzyme immobilization. The behavior of phenolic compounds was investigated by square-wave voltammetry and rutin was selected by presenting the greatest signal. The best performance was obtained with a composition of 70:10:10:10% (w/w/w/w) of the graphite powder:β-CDEP:Nujol:Ir-BMI·PF₆ composition, a PPO concentration of 500 units mL^?1, in 0.1 M phosphate buffer solution (pH 6.0) with frequency, pulse amplitude and scan increment at 100 Hz, 60 mV, and 3.0 mV, respectively. Under optimized conditions, the cathodic currents increased linearly for the rutin concentration range of 1.3 × 10^?7–2.0 × 10^?6 M with a detection limit of 7.9 × 10^?8 M. This sensor demonstrated acceptable repeatability and reproducibility and the results for the rutin recovery ranged from 92.8 to 103.4%. A relative error of 0.7% was obtained in the rutin determination in simulated samples.