Dispersal of plant fragments in small streams

1. Streams are subject to frequent natural and anthropogenic disturbances that cause sediment erosion and loss of submerged vegetation. This loss makes downstream transport and retention of vegetative propagules on the streambed very important for re‐establishing vegetation cover. We measured dispersal and retention of macrophyte stem fragments (15–20 cm long) along 300 m long reaches of four small to medium sized Danish lowland streams. 2. The number of drifting stem fragments declined exponentially with distance below the point of release. This finding makes the retention coefficient (k, m⁻¹) in the exponential equation a suitable measure for comparisons among different macrophyte species, and between stream reaches of different hydrology and vegetation cover. 3. Buoyancy of macrophyte tissue influenced retention. Elodea canadensis stems drifted below the water surface, and were more inclined to be retained in deeper water associated with submerged plants and obstacles in the streambed. Ranunculus peltatus stems were more buoyant, drifted at the water surface, and were more inclined to be trapped in shallow water and in riparian vegetation. 4. The retention coefficient of drifting stems increased with the relative contact between the flowing water and streambed, bank and vegetation. Thus, the retention coefficients were highest (0.02–0.12 m⁻¹) in shallow reaches with a narrow, vegetation‐free flow channel. Here there were no significant differences between E. canadensis and R. peltatus. Retention coefficients were lowest (0.0005–0.0135 m⁻¹) in deeper reaches with wider vegetation‐free flow channels. Retention of E. canadensis was up to 16 times more likely than retention of R. peltatus. 5. Overall, the longitudinal position in the stream system of source populations of species capable of producing numerous stems, the species‐specific retention coefficients of stems, and the retention capacity of stream reaches should be important for species distribution in perturbed stream systems. Retention of stems is probably constrained in headwaters by the small downstream flux of stem fragments because of the restricted source area, and constrained in downstream reaches by small retention coefficients. Macrophyte retention may, consequently, peak in medium‐sized streams.     

Stabilization of freeze-dried Lactobacillus paracasei subsp. paracasei JCM 8130T with the addition of disaccharides,polymers, and their mixtures

Although freeze-drying is a widely used dehydration technique for the stabilizing of unstable lactic acid bacteria, Lactobacillus paracasei subsp. paracasei JCM 8130^T (L. paracasei) is destabilized after freeze-drying and subsequent storage. In order to improve the stability of freeze-dried L. paracasei, effects of disaccharides (sucrose and trehalose), polymers (maltodextrin; MD and bovine serum albumin; BSA), and their mixtures on the survival rate of freeze-dried L. paracasei were investigated. The survival rate of non-additive sample decreased slightly after freeze-drying but decreased drastically after subsequent storage at 37 °C for 4 weeks. The reduction was diminished by the addition of disaccharides and polymers. The stabilizing effect of disaccharides was not affected by the co-addition of MD. In contrast, the disaccharide–BSA mixtures had a synergistic stabilizing effect, and the survival rates were largely maintained even after storage. It is suggested that the synergistic effect originates from the conformational stabilization of the dehydrated bacteria.     

Selection of a potential probiotic Lactobacillus strain and subsequent in vivo studies

The probiotic potential of a Lactobacillus strain, isolated from pig faeces, was assessed as a probiotic in piglets. The strain was examined for resistance to pH 2.0, 0.5% oxgall and antibiotics, and antimicrobial activities against enteric pathogenic bacteria. The probiotic strain, L. reuteri BSA131, was administered through the feed to 25 1-month-old Landrace piglets. The piglets were divided into five groups of five piglets each and fed with different diets for 28 days. The daily consumption of L. reuteriBSA131 was assigned into two groups by the concentration of 10⁶ or 10⁸ freeze-dried bacteria. Fecal samples were collected before, during, and after consumption. Lactobacilli and enterobacteria cell counts were determined in the fecal samples. The liveweight gains and feed consumption of the piglets were recorded daily. This study showed that strain BSA 131 enhanced liveweight gains and feed conversion rates in piglets. It also showed a significant increase in lactobacilli cell counts and decreases in enterobacterial numbers in the fecal samples. Strain BSA 131 was considered to be a potential probiotic for piglets, especially after weaning.     

Histidine maintenance requirement and efficiency of its utilization in young pigs

Abstract

An experiment was conducted in young pigs (initial BW 10.1 kg) to estimate the maintenance requirement for histidine and its efficiency of utilization for protein accretion using a comparative slaughter technique. Three groups of six pigs each were fed a purified diet supplying 0, 14 or 56 mg histidine per kg BW^0.75. Following 21 d of feeding, pigs were killed for whole body compositional analysis. A representative group of six pigs was killed at the beginning of the experiment. Retention of histidine and total N were the main criteria of response. Histidine retention (R² = 0.73) and N retention (R² = 0.78) were linear functions of histidine intake (p < 0.001). Histidine requirement for zero histidine retention was 15.5 mg/kg BW^0.75, whereas histidine required for zero N retention was 4.1 mg/kg BW^0.75. At zero histidine retention, the pigs retained daily 82 mg N/kg BW^0.75, presumably due to the degradation of histidine-rich compounds such as haemoglobin and/or carnosine. The slope of the regression line relating histidine retention to N retention indicated that 105 mg of histidine was deposited per gram of total N which was considerably less than the estimated histidine concentration in body protein (179 mg/g N). Based on the slopes of regression equations for histidine and N retention, marginal efficiency of histidine utilization was calculated to be 0.94 and 1.34, respectively.     

Mechanism of the interaction of aliphatic alcohols with bovine serum albumin in the ternary systems—1H n.m.r. study: 2. Aqueous solutions BSA-alcohols-sulphonamides

To study effect of sulphacetamide and sulphathiazole on the interaction of aliphatic alcohols with bovine serum albumin (BSA) in aqueous solution, ¹H n.m.r. spectra of alcohols (A) and sulphonamides (S) were monitored in D₂O, in the binary systems (A—S), (A—BSA), (S—BSA) and in the ternary system (A—BSA—S) at pH 7.0. The n.m.r. lines of alcohols, markedly and selectively broadened in the systems (A—BSA), were gradually narrowed on addition of increasing concentrations of sulphonamides. The narrowing was dependent on the chain length and branching of the alcohol molecules with residual broadening significantly greater for the α-methylenes or methines next to ?OH. The results suggest the release of alcohol molecules weakly associated to BSA after the formation of the specific sulphonamide—BSA complex. They also reflect selectively strong immobilization of the fragments next to ?OH in the A—BSA complexes, probably by hydrogen bonds between hydroxyls and the peptide groups of protein.     

2-Propanol degradation by Sulfolobus solfataricus

Sulfolobus solfataricus used 2-propanol and 2-propanone (acetone) when grown in static cultures at 78 °C with or without glucose at 10 g l^–1. The presence of 3.92 g 2-propanol l^–1 in both cases inhibited growth. However, acetone accumulation following 2-propanol depletion suggested that 2-propanol was co-metabolized via the acetone metabolic pathway. Glucose at 10 g l^–1 increased 2-propanol and acetone utilization from 0.93 g l^–1 to 1.77 g l^–1 and from 0.11 g l^–1 to 1.62 g l^–1, respectively. Without glucose, immobilized S. solfataricus cells increased the 2-propanol removal rate to 0.035 g l^–1 h^–1, compared to 0.0012 g l^–1 h^–1 by its suspended counterpart. The results suggest the establishment of an immobilized reactor configuration is preferential for the treatment of high temperature solvent waste streams by this acidothermophilic Crenarchaeon.     

Mechanism of the interactions of aliphatic alcohols with bovine serum albumin in the ternary systems—1H n.m.r. study: 1. Aqueous solutions BSA-alcohols-urea

The molecular mechanism of the interaction of aliphatic alcohols (A) with bovine serum albumin (BSA) protein was studied in aqueous solutions at increasing concentrations (0–8 m) of urea (U). ¹H n.m.r. spectra of alcohols were monitored in D₂O in the control binary systems (A—U) and (A—BSA), and in the ternary systems (A—U—BSA) at pH 7.0. Marked and selective broadening of the n.m.r. lines of alcohols in the system (A—BSA) was reduced upon addition of urea, indicating that alcohols are poorly bound by urea-denaturated BSA. The reduction in the ability to associate with BSA depends on chain position of the alcohol molecule and is much higher for α-methylenes (next to ?OH) than for other proton groups. Besides this reduction seems to be a two-step phenomenon dependent upon urea concentration. The results obtained can be explained by competition in formation by the peptide linkages of a protein of the hydrogen bonds with ?OH group of alcohols or fragments of urea molecules.     

A Medium for the Isolation of Capsular Bacteria from Kefir Grains

Secondary alcohols (C₃ to C₁₀) were oxidized to the corresponding methylketones by resting mycelia of Scedosporium sp. A-4 grown on propane, but 3-pentanol and 3-hexanol were not oxidized. The oxidation of 2-propanol to acetone was inhibited by pyrazole, potassium cyanide, sodium azide and Hg^{2 +}. Alcohol dehydrogenase activity was found in the cell-free soluble fraction and this activity requires a cofactor, specifically NAD⁺. The oxidation of both 1-propanol and 2-propanol may be catalyzed by the same alcohol dehydrogenase.     

Investigation of oxidation in freeze-dried membranes using the fluorescent probe C11-BODIPY

Incorporation of the fluorescent probe C11-BODIPY^581/591 in two dried membrane systems, soy bean phosphatidylcholine liposomes freeze-dried in a carbohydrate/protein matrix and Lactobacillus acidophilus (La-5) freeze-dried in a carbohydrate matrix, was successful and could be visualised by Confocal Laser Scanning Microscopy (CLSM). The C11-BODIPY^581/591 probe is a lipid oxidation reporter molecule, which is known to associate with the lipids of biological membranes and exhibit a fluorescence shift from the red range to the green range of the visible spectrum when it is oxidised together with the lipids. The present study is the first to demonstrate that the C11-BODIPY^581/591 probe can be used in dried membrane systems, and that a detection of oxidation is possible by CLSM analysis directly on the dried samples.     

Immobilization of Candida rugosa lipase by cross-linking with glutaraldehyde followed by entrapment in alginate beads

Candida rugosa lipase was immobilized by first cross-linking with glutaraldehyde and then entrapping in calcium alginate beads. The presence of 2-propanol during cross-linking markedly improved the enzyme activity and activity recovery. Maximal enzyme activity (2.1?mmol?h^?1?g^?1 immobilized conjugate, wet weight) and activity recovery (117%) were observed at 30% (v/v) 2-propanol for hydrolysis of olive oil, which were 1.7 and 2.0 times higher than those of the immobilized enzyme prepared in the absence of 2-propanol. The half-life of the immobilized lipase prepared by entrapment after cross-linking in 30% 2-propanol was 1.6 times higher than that prepared by entrapment of the native lipase without cross-linking and 2-propanol pretreatment. The enantioselectivity of the former was 11 times higher than that of the latter for hydrolysis of racemic ketoprofen ethyl ester.     

Soluble reactive phosphorus (SRP) transport and retention in tropical, rain forest streams draining a volcanic landscape in Costa Rica: in situ SRP amendment to streams and laboratory studies

Soluble reactive phosphorus (SRP) transport/retention was determined in two rain forest streams (Salto, Pantano) draining La Selva Biological Station, Costa Rica. There, SRP levels can be naturally high due to groundwater enriched by geothermal activity within the surfically dormant volcanic landscape, and subsequently discharged at ambient temperature. Combined field and laboratory approaches simulated high but natural geothermal SRP input with the objective of estimating the magnitude of amended SRP retention within high and low SRP settings and determining the underlying mechanisms of SRP retention. First, we examined short-term SRP retention/transport using combined SRP-conservative tracer additions at high natural in situ concentrations. Second, we attempted to observe a DIN response during SRP amendment as an indicator of biological uptake. Third, we determined SRP release/retention using laboratory sediment assays under control and biologically inhibited conditions. Short-term in situ tracer-SRP additions indicated retention in both naturally high and low SRP reaches. Retention of added SRP mass in Upper Salto (low SRP) was 17% (7.5 mg-P m⁻² h⁻¹), and 20% (10.9 mg-P m⁻² h⁻¹) in Lower Salto (high SRP). No DIN response in either nitrate or ammonium was observed. Laboratory assays using fresh Lower Salto sediments indicated SRP release (15.4 ± 5.9 μg-P g dry wt.⁻¹ h⁻¹), when incubated in filter sterilized Salto water at ambient P concentration, but retention when incubated in filter sterilized river water amended to 2.0 mg SRP l⁻¹ (233.2 ± 5.8 μg-P g dry wt.⁻¹ h⁻¹). SRP uptake/release was similar in both control- and biocide-treated sediments indicating predominantly abiotic retention. High SRP retention even under biologically saturated conditions, absence of a DIN response to amendment, patterns of desorption following amendment, and similar patterns of retention and release under control and biologically inhibited conditions all indicated predominantly abiotic P flux.     

Study on the interactions of mapenterol with serum albumins using multi‐spectroscopy and molecular docking

The interactions of mapenterol with bovine serum albumin (BSA) and human serum albumin (HSA) have been investigated systematically using fluorescence spectroscopy, absorption spectroscopy, circular dichroism (CD) and molecular docking techniques. Mapenterol has a strong ability to quench the intrinsic fluorescence of BSA and HSA through static quenching procedures. At 291 K, the binding constants, K_a, were 1.93 × 10³ and 2.73 × 10³ L/mol for mapenterol–BSA and mapenterol–HAS, respectively. Electrostatic forces and hydrophobic interactions played important roles in stabilizing the mapenterol–BSA/has complex. Using site marker competitive studies, mapenterol was found to bind at Sudlow site I on BSA/HSA. There was little effect of K⁺, Ca²⁺, Cu²⁺, Zn²⁺ and Fe³⁺ on the binding. The conformation of BSA/HSA was changed by mapenterol, as seen from the synchronous fluorescence spectra. The CD spectra showed that the binding of mapenterol to BSA/HSA changed the secondary structure of BSA/HSA. Molecular docking further confirmed that mapenterol could bind to Sudlow site I of BSA/HSA. According to Förster non‐radiative energy transfer theory (FRET), the distances r₀ between the donor and acceptor were calculated as 3.18 and 2.75 nm for mapenterol–BSA and mapenterol–HAS, respectively. Copyright © 2015 John Wiley & Sons, Ltd.     

Exploring the interactions of a Tb(III)–quercetin complex with serum albumins (HSA and BSA): spectroscopic and molecular docking studies

Serum albumins (human serum albumin (HSA) and bovine serum albumin (BSA), two main circulatory proteins), are globular and monomeric macromolecules in plasma that transport many drugs and compounds. In the present study, we investigated the interactions of the Tb(III)–quercetin (Tb–QUE) complex with HSA and BSA using common spectroscopic techniques and a molecular docking study. Fluorescence data revealed that the inherent fluorescence emission of HSA and BSA was markedly quenched by the Tb–QUE complex through a static quenching mechanism, confirming stable complex formation (a ground‐state association) between albumins and Tb–QUE. Binding and thermodynamic parameters were obtained from the fluorescence spectra and the related equations at different temperatures under biological conditions. The binding constants (K_b) were calculated to be 0.8547 × 10³ M^?1 for HSA and 0.1363 × 10³ M^?1 for BSA at 298 K. Also, the number of binding sites (n) of the HSA/BSA–Tb–QUE systems was obtained to be approximately 1. Thermodynamic data calculations along with molecular docking results indicated that electrostatic interactions have a main role in the binding process of the Tb–QUE complex with HSA/BSA. Furthermore, molecular docking outputs revealed that the Tb–QUE complex has high affinity to bind to subdomain IIA of HSA and BSA. Binding distances (r) between HSA–Tb–QUE and BSA–Tb–QUE systems were also calculated using the Forster (fluorescence resonance energy transfer) method. It is expected that this study will provide a pathway for designing new compounds with multiple beneficial effects on human health from the phenolic compounds family such as the Tb–QUE complex.     

Adsorption and elution behaviors of bovine serum albumin in metal-chelated affinity cryogel beds

Metal-chelated supermacroporous cryogels are effective supports for affinity chromatographic separation of biomolecules in downstream processes. In this work, polyacrylamide cryogel beds were prepared in glass columns (16 mm inner diameter) and coupled with iminodiacetic acid (IDA). These cryogels were loaded with Zn²⁺ and Ni²⁺ and the so-called Zn²⁺-IDA-cryogels and Ni²⁺-IDA-cryogels were obtained. Permeabilities and height equivalent to theoretical plates (HETPs) of these cryogel beds were measured and the cryogel structure was analyzed using scanning electron microscopy (SEM). Bovine serum albumin (BSA) was employed as a model protein to elucidate the adsorption and elution behaviors of these cryogels under various conditions, such as different flow rate, solution pH, and composition of the eluents. The results showed that the Zn²⁺-IDA-cryogels and Ni²⁺-IDA-cryogels in this study had interconnected supermacropores and high water permeabilities (∼10⁻¹¹ m²). The loading flow velocity had a weak influence on the breakthrough curves and binding capacities for BSA, while the solution pH had an evident effect on the binding capacities for BSA in these cryogels. Maximum binding capacity for BSA was observed near the isoelectric point of BSA. The bound BSA can be eluted effectively using an imidazole solution. A low-eluting flow rate was found to be beneficial to the elution process. Possible mechanisms were proposed and discussed.     

Fruit Volatile Analysis Using an Electronic Nose

Numerous and diverse physiological changes occur during fruit ripening, including the development of a specific volatile blend that characterizes fruit aroma. Maturity at harvest is one of the key factors influencing the flavor quality of fruits and vegetables¹. The validation of robust methods that rapidly assess fruit maturity and aroma quality would allow improved management of advanced breeding programs, production practices and postharvest handling. Over the last three decades, much research has been conducted to develop so-called electronic noses, which are devices able to rapidly detect odors and flavors^2-4. Currently there are several commercially available electronic noses able to perform volatile analysis, based on different technologies. The electronic nose used in our work (zNose, EST, Newbury Park, CA, USA), consists of ultra-fast gas chromatography coupled with a surface acoustic wave sensor (UFGC-SAW). This technology has already been tested for its ability to monitor quality of various commodities, including detection of deterioration in apple⁵; ripeness and rot evaluation in mango⁶; aroma profiling of thymus species⁷; C₆ volatile compounds in grape berries⁸; characterization of vegetable oil⁹ and detection of adulterants in virgin coconut oil¹⁰. This system can perform the three major steps of aroma analysis: headspace sampling, separation of volatile compounds, and detection. In about one minute, the output, a chromatogram, is produced and, after a purging cycle, the instrument is ready for further analysis. The results obtained with the zNose can be compared to those of other gas-chromatographic systems by calculation of Kovats Indices (KI). Once the instrument has been tuned with an alkane standard solution, the retention times are automatically converted into KIs. However, slight changes in temperature and flow rate are expected to occur over time, causing retention times to drift. Also, depending on the polarity of the column stationary phase, the reproducibility of KI calculations can vary by several index units¹¹. A series of programs and graphical interfaces were therefore developed to compare calculated KIs among samples in a semi-automated fashion. These programs reduce the time required for chromatogram analysis of large data sets and minimize the potential for misinterpretation of the data when chromatograms are not perfectly aligned.We present a method for rapid volatile compound analysis in fruit. Sample preparation, data acquisition and handling procedures are also discussed.     

Chiral separation of tryptophan enantiomers by liquid chromatography with BSA-silica stationary phase

The separation of tryptophan enantiomers was carried out with medium-pressure liquid chromatography using BSA (bovine serum albumin)-bonded silica as a chiral stationary phase. The influence of various experimental factors such as pH and ionic strength of mobile phase, separation temperature, and the presence of organic additives on the resolution was studied. In order to expand this system to preparative scale, the loadability of sample and the stability of stationary phase for repeated use were also examined. The separation of tryptophan enantiomers was successful with this system. The data indicated that a higher separation factor (α) was obtained at a higher pH and lower temperature and ionic strength in mobile phase. Addition of organic additives (acetonitrile and 2-propanol) in mobile phase contributed to reduce the retention time of L-tryptophan. About 30% of the separation factor was reduced after 80 days of repeated use.     

Biodegradation of VOCs from printing press air by an on-site pilot plant bioscrubber and laboratory scale continuous yeast cultures

The volatile organic compound composition (VOCs) of printing press air wasfound to contain mostly ethanol, but also ethyl acetate, 1-propanol, 2-propanol,1-methoxy-2-propanol and 3-ethoxy-1-propanol. A pilot plant bioscrubber inoculatedwith a mixed microbial population was constructed on-site. The bioscrubber wasable to treat the polluted gas efficiently. It, however, suffered from strong wall growthand blockages in the column. The efficiencies of the pilot plant and a bioreactor iscompared. The yeasts Candida guilliermondii and Saccharomyces cerevisiae known to tolerate ethanol were selected instead of mixed population to avoid the wall growth and blockages in the bioreactor. The removal of the VOCs both individually and as a complex mixture was tested in a microcultivation system and in continuous chemostat cultures with and without cell recycling. The Candida yeast could use all the compounds as a carbon source while growth of S. cerevisiae was markedly slower on the methoxylated and ethoxylated propanols. Best total removal of the VOCs was 99% and achieved by C. guilliermondii. The only compound that was not totally removable in the chemostat experiment with C. guilliermondii was 1-methoxy-2-propanol. In laboratory scale the total and volumetric removal of VOCs by C. guilliermondii was more efficient compared to the pilot plant encouraging to scale up and applying the yeast bioreactor to real field conditions.     

Preparation of thermoresponsive cationic copolymer brush surfaces and application of the surface to separation of biomolecules

We have prepared poly( N-isopropylacrylamide (IPAAm)- co-2-(dimethylamino)ethylmethacrylate (DMAEMA)) brush-grafted silica bead surfaces through surface-initiated atom transfer radical polymerization (ATRP) using the CuCl/CuCl 2/Me 6TREN catalytic system in 2-propanol at 25 degrees C for 16 h. The prepared temperature-responsive surfaces were characterized by chromatographic analysis using the modified silica beads as stationary phases. Chromatographic retention times for adenosine nucleotides in aqueous mobile phases were significantly increased compared to that previously reported for other cationic hydrogel surfaces, indicating that strong electrostatic cationic copolymer brush interactions occur between the surfaces and nucleotide analytes. Retention times for adenosine nucleotides significantly decreased with increasing column temperature, explained by the decreasing basicity in the copolymer with increasing temperature. Step-temperature gradients from 10 to 50 degrees C shorten ATP retention times. These results indicate that cationic copolymer brush surfaces prepared by ATRP can rapidly alter their electrostatic properties by changing aqueous temperature.     

Gas Chromatographic Determination of Optical Isomers of α-Phenylethylamine and α-Phenyl-β-(p-tolyl)-ethylamine on Optically Active Stationary Phases

The nondialyzable melanoidins prepared from glucose-butylamine (I) and xylose–butylamine (II) reaction systems, freeze-dried powder obtained from the dialyzable fraction of the glucose–butylamine reaction system (III) and N-butyl-glucosylamine (IV) were pyrolyzed at 350°C for 0.5-2 hr and the volatile pyrolysate was investigated. To trap the volatile compounds, Tenax GC trapping and cold trapping methods were used. Identification of these volatiles was made by gas chromatography-mass spectrometry, using a glass capillary column. The volatile components in the pyrolysates of I, II, III and IV were qualitatively similar to each other. The major volatile components in the pyrolysates of I, II, III and IV were identified as two furans, 1-butanol, two 1-butylpyrroles, 1-butylpyrrolidine, 1-butylaziridine and two N-butylamides. The results are discussed in relation to those obtained from previously investigated sugar-amino acid melanoidins.     

Affinity extraction of BSA with reversed micellar system composed of unbound Cibacron Blue

Affinity Cibacron Blue 3GA (CB) dye in aqueous phase was directly transferred to the reversed micelles due to electrostatic interaction between anionic CB and cationic cetyltrimethylammonium bromide (CTAB). The bovine serum albumin (BSA) transfer to the reverse micelles increases significantly in a wide range of pH by the addition of a small amount of CB ( approximately 1.0-7.0% of the total surfactant concentration) to the aqueous phase. For pH < pI, the selectivity can be significantly improved with the presence of affinity CB because no BSA was extracted in the absence of CB. For backward extraction of BSA from the micellar phase with stripping aqueous solution, the addition of 2-propanol to the aqueous phase can recover almost all BSA (98.5%) extracted into the reverse micelles.