Effects of Pulsed Electric Field (PEF) Treatment on Enhancing Activity and Conformation of α-Amylase

To explore an efficient, safe, and speedy application of pulsed electric field (PEF) technology for enzymatic modification, effects of PEF treatment on the enzymatic activity, property and kinetic parameters of α-amylase were investigated. Conformational transitions were also studied with the aid of circular dichroism (CD) and fluorescence spectra. The maximum enzymatic activity of α-amylase was obtained under 15 kV/cm electric field intensity and 100 mL/min flow velocity PEF treatment, in which the enzymatic activity increased by 22.13 ± 1.14 % compared with control. The activation effect could last for 18 h at 4 °C. PEF treatment could widen the range of optimum temperature for α-amylase, however, it barely exerted any effect on the optimum pH. On the other hand, α-amylase treated by PEF showed an increase of V _max, t_1/2 and ΔG, whereas a decrease of K _m and k were observed. Furthermore, it can be observed from fluorescence and CD spectra that PEF treatment had increased the number of amino acid residues, especially that of tryptophan, on α-amylase surface with enhanced α-helices by 34.76 % and decreased random coil by 12.04 % on α-amylase when compared with that of untreated. These changes in structure had positive effect on enhancing α-amylase activity and property.     

Effect of Trehalose on Oligomeric State and Anti-Aggregation Activity of αB-Crystallin

Biochemistry (Moscow) - αB-Crystallin (αB-Cr), one of the main crystalline lens proteins, along with other crystallins maintains lens transparency suppressing protein aggregation and thus...     

Effect of Enhanced UV-B Radiation on Growth,Yield and Stable Carbon Isotope Composition in Glycine max Cultivars

Effects of enhanced ultraviolet-B (UV-B) radiation on growth, yield and stable carbon isotope composition (δ13C value) in ten cultivars of Glycine max (L.) Merr. were investigated under field conditions. Supplemental UV-B irradiation simulated a 20% stratospheric ozone depletion in Lanzhou on summer solstice day. UV-B radiation reduced biomass and yield in all soybean cultivars by 24.2% and 23.3%, respectively. However, the harvest index increased in 6 of ten soybean cultivars but reduced in 4 cultivars, the average increment was 1.39%. As compared with control, the decrease in δ13C value by UV-B was observed in most cultivars, except in cutlivar “8907-32” increase was found. There were also organ differences of stable carbon isotope composition under enhanced UV-B irradiation. δ13C of roots was the highest and of leaves was the lowest, δ13C value in stem was higher than in seeds. The results indicated that UV-B enhancement might change the metabolic process and the allocation of metabolite.     

Extremely Low-Frequency Magnetic Exposure Appears to Have No Effect on Pathogenesis of Alzheimer’s Disease in Aluminum-Overloaded Rat

Objective

Extremely low-frequency magnetic field (ELF-MF) has been reported to be of potential pathogenetic relevance to Alzheimer''s disease (AD) for years. However, evidence confirming this function remains inconclusive. Chronic Al treatment has been identified as a contributing factor to cognitive function impairment in AD. This study aims to examine whether or not ELF-MF and Al have synergistic effects toward AD pathogenesis by investigating the effects of ELF-MF with or without chronic Al treatment on SD rats.

Methods

Sprague-Dawley (SD) rats were subjected one of the following treatments: sham (control group), oral Al (Al group), ELF-MF (100 µT at 50 Hz) with oral Al (MF+Al group), or ELF-MF (100 µT at 50 Hz) without oral Al (MF group).

Results

After 12 wk of treatment, oral Al treatment groups (Al and MF+Al groups) showed learning and memory impairment as well as morphological hallmarks, including neuronal cell loss and high density of amyloid-β (Aβ) in the hippocampus and cerebral cortex. ELF-MF without Al treatment showed no significant effect on AD pathogenesis. ELF-MF+Al treatment induced no more damage than Al treatment did.

Conclusions

Our results showed no evidence of any association between ELF-MF exposure (100 µT at 50 Hz) and AD, and ELF-MF exposure does not influence the pathogenesis of AD induced by Al overload.     

The Effect of a “Zero” Magnetic Field on the Production of Reactive Oxygen Species in Neutrophils

Exposure of mouse peritoneal neutrophils to hypomagnetic conditions (magnetic shielding, a residual static magnetic field of 20 nT) for 1.5 h decreased the level of intracellular reactive oxygen species as recorded by changes in the fluorescence intensity of 2,7-dichlorodihydrofluorescein and dihydrorhodamine 123 oxidation products. The effect of a hypomagnetic field was similarly observed after adding a respiratory burst activator (the formylated peptide N-formyl–Met–Leu–Phe or phorbol 12-meristate-13-acetate) to a low concentration.     

Bacterial Activity and Bacterioplankton Diversity in the Eutrophic River Warnow��Direct Measurement of Bacterial Growth Efficiency and Its Effect on Carbon Utilization

The influence of bacterial activity and diversity on bacterial growth efficiency was investigated in a flatland river. Eutrophic River Warnow drains predominantly agricultural land and is heavily loaded with nutrients, dissolved and particulate organic matter (DOM and POM), especially humic substances. Although the water column bacterial community consists of many inactive or damaged cells, bacterioplankton sustained a high bacterial secondary production of 0.2?C14.5???g C L^?1 h^?1 and a high DNA synthesis (thymidine uptake) of 6.1?C15.5???g C L^?1 h^?1. The direct and short-term measurement of bacterial respiration (by optodes) revealed high respiration rates especially in summer leading to directly estimated bacterial growth efficiencies (BGE) of 2?C28%. These values are compared to calculations based only on bacterial production, which considerably overestimated BGEs. From all these data, River Warnow can be characterized as a strongly remineralizing system. River Warnow was dominated among others by Cytophaga/Flavobacteria and Actinobacteria which are typical for organic rich waters because of their ability to degrade high molecular weight compounds. However, community composition did not significantly affect BGE.     

The Combined Effect of Shungite and Heavy Metals on the Growth of Microalgae Роpulation

The combined effect of 3 mg/L potassium dichromate, 1.5 mg/L cadmium sulfate, and 100 g/L shungite on the growth of chlorococcales green microalgae culture Scenedesmus quadricauda (Turp.) Bréb. is studied. The toxic effect of potassium dichromate and cadmium sulfate on S. quadricauda is estimated by calculating the share of living and dead cells and physiological parameters. The toxic effect of heavy metals does not manifest itself under the combined action of potassium dichromate or cadmium sulfate and shungite on S. quadricauda. The best growth of the algae culture occurred only when only shungite was added to the culture medium. Shungite can be used to neutralize the toxic effect of heavy metals.     

Immunoresponsiveness in Ulcerative Colitis and Crohn's Disease—Effect of Colectomy and Suppression of Disease Activity

We evaluated the effect of medically induced symptomatic disease improvement on in vitro tests of cell-mediated immune responses in 33 patients with Crohn''s disease. When results obtained in 17 patients with ulcerative colitis were compared with those of 10 patients with ulcerative colitis who had undergone a colectomy, no significant correlation was detected between individual clinical and laboratory variables or the Crohn''s disease activity index and in vitro tests of cell-mediated immunity. A different pattern emerged from the longitudinal tests of cell-mediated immunity: when these test results were initially abnormal in patients with Crohn''s disease, clinical improvement as assessed by the Crohn''s disease activity index was associated with normalizing cell-mediated immunity. In contrast, when the test results were initially normal, clinical improvement was not associated with any change in the immune response. Following colectomy in patients with ulcerative colitis, some abnormalities of suppressed immune responses remained, although patients were cured of their disease. Factors other than clinical disease activity may be responsible for the suppressed immunoresponsiveness in some patients with inflammatory bowel disease, and variable changes in cell-mediated immunity occur after both surgical and medical treatment.     

Effect of Long-Term Exposure to a Randomly Varied 50 Hz Power Frequency Magnetic Field on the Fertility of the Mouse

A double blind study on BALB/c mice was conducted to examine the effects of extremely low-frequency electromagnetic fields on fertility. The mice were continuously exposed or sham-exposed from conception for two generations to magnetic fields varying between 0.5 and 77?μT. Biological parameters related to fertility were evaluated. Serum testosterone levels and mass of testes and adrenals were determined. No significant difference was found between the sham-exposed and exposed groups for all the biological endpoints, except for sperm motility. A significant difference between the two groups was found prior to the swim-up test with quantitative analysis of sperm motility as well as after the swim-up test for quantitative and qualitative analysis of sperm motility. ELF-EMFs significantly decreased the number of living sperm and the quality of movement of sperm, although these adversities did not impact on the outcome of the other parameters investigated.     

Effect of Epidermal Growth Factor on Follicular Development and Steroidogenesis in Perfused Rat Ovary

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Effect of Zn（Ⅱ） on the Structure and Biological Activity of Natural β-NGF

Only β-NGF, the subunit of the 7S NGF complex, exhibits NGF activity, but the function ofthe zinc ion in native β-NGF has received little attention. Flameless atomic absorption spectroscopy (FAAS)measurements reveal that native β-NGF contains Zn(Ⅱ) with a Zn(Ⅱ)/β-NGF stoichiometry of 1 : 14.6.The presence of Zn(Ⅱ) in the native molecule results in significant changes of the secondary structure andlocal tertiary structure around Trp(s) with respect to those of apo β-NGF, as suggested by spectra offluorescence and circular dichrosim. Stopped-flow studies show that there are at least two steps during theinteraction of Zn(Ⅱ) with the apo form. In comparison with its apo form, the native β-NGF shows a higherability to trigger the proliferation of TF1 cells and mediate the survival of PC 12. Thus it is most likely that thestructural changes caused by the presence of Zn(II) directly lead to the increase in the biological activity of β-NGE All results indicate that Zn(Ⅱ) in native β-NGF plays an important role in the structure and thebiological activity of the protein.     

Phytoremediation in the Tropics—The Effect of Crude Oil on the Growth of Tropical Plants

Phytoremediation is a nondestructive, cost-effective in-situ technology to clean up contaminated soils. In the case of contamination with petroleum hydrocarbons, plants enhance microbial degradation of the contaminant in the rhizosphere. The potential of this technology for the tropics should be high due to prevailing climatic conditions favoring plant growth and stimulating microbial activity. Investigations of the potential of tropical plants for phytoremediation, however, are scarce. The present work studied two grasses and six legumes from the eastern savannah of Venezuela on their reaction to crude oil contamination in soil. Results shall help to identify plants with a potential for phytoremediation and subsequent studies. Seedling emergence and biomass production were determined for plants growing in soil contaminated with 0%, 3%, and 5% heavy crude oil. Contamination had, in general, a tendential but not significant negative influence on seedling emergence. Dry matter production was reduced by only a few percent to up to 85%. Furthermore, in some legumes inhibition of nodulation was observed. The grass Brachiaria brizantha and the legumes Centrosema brasilianum and Calopogonium mucunoides are promising for phytoremediation because in contaminated soil they combined high seedling emergence with least affected biomass production. Since they are cultivated forage/soil cover species also in other regions of the tropics, their potential for phytoremediation of petroleum contaminated soils extends beyond Venezuela.     

Effect of competition on the demography of planktonic cladocerans — Daphnia and Diaphanosoma

Summary Isolated and mixed continuous cultures of Daphnia hyalina and Diaphanosoma brachyurum in lake water were maintained under laboratory conditions to elucidate demographic effects of competition. Population dynamics curves were obtained. Interspecific competition was revealed by the decrease in the average density of animals in the mixed versus isolated cultures and by the extinction of one species in the presence of the other. Within the first 50 days either Diaphanosoma (4 cases) or Daphnia (1 case) was the superior competitor, depending on the initial conditions. Further cultivation resulted in the extinction of Diaphanosoma in the mixed cultures. There were no statistically significant differences between the maximum rates of population increase (r _m ) in Daphnia and Diaphanosoma at the concentration of edible algae about 2·10⁵ m³ml^-1(0.293 and 0.286 days^-1, respectively). Time lags for density-dependent parameters of the populations were evaluated by means of rank cross-correlations. Regardless of the species identity the time lags of fecundity, birth rate, and the rate of population growth were significantly higher in the superior competitor. The initial conditions of culturing affected the time lags which in their turn influenced the outcome of the interaction. Enhanced competitive ability due to the maximized time lags in Daphnia was not associated with the loss of population stability. Conversely, it brought about destabilization of Diaphanosoma populations which seemed to be the ultimate cause of its extinction observed in the end of the experiment. Time lag of the population growth rate was well predicted based on the half-sum of time lags in birth and death rates (r²=0.80, P<0.001). Daphnia responded to competition with a sharp shortening of the time lags of fecundity, birth rate, and the population growth rate. It increased clutch size and showed inverse relationship between the fecundity time lag and average fecundity even though it was strongly suppressed by Diaphanosoma. The competitive ability was not related to the percentage of adults in the populations. In contrast to the current belief the major result of interspecific competition in the experiment was not a decrease in the rate of population growth but was a reduction in population time lags.     

Effect of Cu2+ on PSⅡ Activity and Energy Transfer of Phycobillisome in Intact Cells of Spirulina platensis

Addition of Cu2+ at low concentrations, to intact cells of the cyanobacterium, Spirulina platensis, at room temperature, caused an enhancement in intensity of fluorescence emitted by phycocyanin and induced a blue shift at the emission peak, both of which indicated changes in energy transfer within the phycobillisomes. Cu2+ also suppressed the whole-chain electron transport activity (H2O→MV) and water-splitting activity of the photosystem Ⅰ. When isolated phycocyanin and allophycocyanin were exposed to very low concentrations of Cu2+ ions, C-phycocyanin but not allophycocyanin, exhibited decrease not only in the absorbance in the longer wavelength (616--620 nm) region, but also in the fluorescence emission intensity at 647 nm accompanied by a blue shift to 643 nm. These results suggested that Cu2+ selectively bleach C-phycocyanin.     

Distribution of aquatic yeasts — Effect of incubation temperature and chloramphenicol concentration on isolation

Fresh (river), estuarine, and marine waters in and along the coastline of Connecticut were cultured by the membrane filter technique at 20 and 37°C on a complex medium containing 0–1000 mg/L of chloramphenicol. Using counts on medium with 500 mg/L antibiotic as a base, ratios of total and pink yeast counts were recorded for other chloramphenicol concentrations at both temperatures for the waters sampled. Variable results were obtained; in general, both total and pink yeast counts decreased with increasing antibiotic levels, being most apparent at > 400 mg/L chloramphenicol. Medium without antibiotic and with 100 mg/L always produced baterial overgrowth. A total of 209 white yeasts were isolated from all platings; the genera Torulopsis, particularly T. Candida, and Candida were dominant with lesser numbers of Cryptococcus, Trichosporon, sporogenous genera, and Kloeckera. Most species isolated were found on media at all chloramphenicol levels. Comparisons were made of yeast distributions in these temperate waters with reports from other areas.Contribution No. 101 from the University of Connecticut Marine Research Laboratory.     

Studies on Tolfenamic Acid–Chitosan Intermolecular Interactions: Effect of pH, Polymer Concentration and Molecular Weight

Solid-state properties of tolfenamic acid (TA) and its complexes with chitosan (CT) have been studied. Effect of medium pH, molecular weight of polymer and its different concentrations on these TA–CT complexes were studied in detail. Low and medium molecular weight CT have been used in different ratios at pH ranging from 4 to 6 and freeze-drying technique has been employed to modify the appearance of crystalline TA. Physical properties of the formed complexes have been studied by employing X-ray diffraction, differential scanning calorimetry and scanning electron microscopy; chemical structure has been studied using Fourier transform infrared spectroscopy. The results showed that both forms of the polymer exhibited complete conversion in 1:8 ratio at pH 4, 1:4 at pH 5 and 1:1 at pH 6 indicating a marked effect of pH on drug–polymer complexation. The percent crystallinity calculations indicated low molecular weight CT slightly more effective than the other form. No changes in the complexes have been observed during the 12 week storage under controlled conditions. Both forms of CT at different pH values indicated retardation of recrystallization in TA during cooling of the melt from 1:1 ratios exhibiting formation of strong intermolecular hydrogen bonding between the drug and the polymer.     

The Aversive Effect of Electromagnetic Radiation on Foraging Bats—A Possible Means of Discouraging Bats from Approaching Wind Turbines

Large numbers of bats are killed by collisions with wind turbines and there is at present no accepted method of reducing or preventing this mortality. Following our demonstration that bat activity is reduced in the vicinity of large air traffic control and weather radars, we tested the hypothesis that an electromagnetic signal from a small portable radar can act as a deterrent to foraging bats. From June to September 2007 bat activity was compared at 20 foraging sites in northeast Scotland during experimental trials (radar switched on) and control trials (no radar signal). Starting 45 minutes after sunset, bat activity was recorded for a period of 30 minutes during each trial and the order of trials were alternated between nights. From July to September 2008 aerial insects at 16 of these sites were sampled using two miniature light-suction traps. At each site one of the traps was exposed to a radar signal and the other functioned as a control. Bat activity and foraging effort per unit time were significantly reduced during experimental trials when the radar antenna was fixed to produce a unidirectional signal therefore maximising exposure of foraging bats to the radar beam. However, although bat activity was significantly reduced during such trials, the radar had no significant effect on the abundance of insects captured by the traps.     

Growth and lipid production of Umbelopsis isabellina on a solid substrate—Mechanistic modeling and validation

Microbial lipids are an interesting feedstock for biodiesel. Their production from agricultural waste streams by fungi cultivated in solid-state fermentation may be attractive, but the yield of this process is still quite low. In this article, a mechanistic model is presented that describes growth, lipid production and lipid turnover in a culture of Umbelopsis isabellina on κ-carrageenan plates containing the monomers glucose and alanine as C-source and N-source, respectively, and improves the understanding of the complex solid-state system. The model includes reaction kinetics and diffusion of glucose, alanine and oxygen. It is validated empirically and describes the different phases of the culture very well: exponential growth, linear growth because of oxygen limitation, accumulation of lipids and carbohydrates after local N-depletion and turnover of lipids after local C-depletion. Extending the model with an unidentified extracellular product improved the fit of the model to the data. The model shows that oxygen limitation is extremely important in solid-state cultures using monomers, and explains the difference in production rate with submerged cultures. However, the results also show that the specific lipid production rate in solid-state cultures is much lower than in submerged cultures, which results in a low lipid yield.