Cation transport in nanopores

Using periodic boundary conditions and external electric potential field, we have simulated an ion current flow through a flexible nanopore using cations and an explicit extended simple point charge (SPC/E) water with molecular dynamics simulation. The simulation voltages range goes beyond the usual ionic channel measurements ( ± 1 V) and yields useful information about density profiles, current density distribution and current–voltage (I–V) characteristics.     

A New Lignan (Polonilignan) and Inhibitors of Nitric Oxide Production from Penicillium polonicum,an Endophytic Fungi of Piper nigrum

Inhibiting nitric oxide (NO) or its production is found to be of therapeutic benefit. To discover natural small molecule inhibitors of NO production, a bioassay- and LC/MS-guided chemical investigation was done on the metabolites of endophytic fungus isolated from fresh Piper nigrum fruits. The isolated pure strain was identified as Penicillium polonicum by 16S rDNA sequence comparison. The culture broth extract of P. polonicum (EEPP) exhibited a significant reduction of NO production (Griess method) in LPS-stimulated RAW 264.7 cells (P<0.0001). To understand the chemical constituents of bioactive EEPP, column chromatography and p-TLC studies were carried out, which yielded eight pure compounds. They were characterised as botryosphaeridione ( 1 ), 3-(3,5-di-tert-butyl-4-hydroxy)phenylpropionic acid ( 2 ), variabilone ( 3 ), 2,4-di-tert-butylphenol ( 4 ), indole-3-carboxylic acid ( 5 ), tyrosol ( 6 ), ethyl ferulate ( 7 ) and a new lignan ( 8 ) based on the spectral analysis. The structure elucidation of the new lignan, named polonilignan ( 8 ), was based on HR-MS, ¹H- & ¹³C-NMR, H−H COSY, HSQC and HMBC spectra. Compounds 2 , 4 , 5 and 6 showed a significant decrease (P<0.0001) in the production of NO in LPS-induced RAW 264.7 cells. Tyrosol ( 6 ) and indole-3-carboxylic acid ( 5 ) controlled nitrite release with IC₅₀ values of 22.84 and 55.01 μM, respectively. This is the first report of (i) P. polonicum as an endophytic fungus of pepper fruits, (ii) isolation of compounds 1 – 8 except 6 from P. polonicum culture broth extract and (iii) NO inhibition effect of 2 , 4 , 5 and 6 .     

Characterisation of a thermostable and proteolysis resistant phytase from Penicillium polonicum MF82 associated with the marine sponge Phorbas sp.

Abstract

Phytases are widely used in human and animal nutrition, aquaculture, soil amendment, and in the production of lower myo-inositol phosphates for clinical purposes. Some of these applications, especially feed industry require robust enzymes. Since the marine environments are less studied compared to terrestrial environments, we evaluated the extracellular phytase activity of 110 marine derived filamentous fungal (MDFF) strains previously isolated from sponge and sediment samples of the Turkey. MDFF strains were qualitatively screened for their extracellular phytase activities and P. polonicum MF82 phytase was further characterized following partial purification. Optimum pH and temperature were determined as 5.5 and 60?°C respectively. A significant relative phytase activity was observed in the presence of urea and acetone. However, there was no phytase activity followed by the treatment with Triton X-100 and Tween 80. Characterization studies revealed that P. polonicum MF82 phytase has superior properties for industrial use including wide pH and temperature range for activity, high optimum activity temperature, high thermal and pH stability, resistance to many enzyme inhibitors including various heavy metals, denaturants, detergents, proteases and organic solvents. Phytase extracellularly produced by P. polonicum MF82 strain presents a good candidate for commercial applications. This study demonstrates that the MDFF strains are prolific sources for phytase and presents the first report about the production and characterization of the phytase from a marine-derived P. polonicum strain.     

Molecular dynamics simulations of ion separation in nano-channel water flows using an electric field

ABSTRACT

Removal of undesired substances from water is a field of investigation recently focused at the nanoscale. Towards this direction, molecular dynamics simulations are conducted in this paper to investigate unwanted ion removal in nanochannel flows. The simulation method incorporates a Poiseuille-like water/ion flow system at the nanoscale where an electric field, of various magnitudes in the range of E?=?0.25–1.5?V/Å, is applied perpendicular to the flow, leading anions and cations close to the wall regions, similar to the Capacitive De-Ionization method. The time needed for ions to reach equilibrium, i.e. to flow in the region near the walls while pure water flows in the channel interior, is t?=?1.3?ns when E?=?1.5?V/Å and t?=?4.0?ns when E?=?0.25?V/Å, showing a dependency on the value of the electric field. Calculations on density, velocity, and temperature values report on fluid properties to be used in the proposed desalination configuration and could act as a basis to guide novel technological applications and extend to higher scales.     

Transport phenomena in a model membrane accompanying a conformational change: Transient processes in response to external stimuli

Summary A model membrane composed of a filter paper and dioleylphosphate was studied by applying various kinds of external stimuli. When the concentration in the external solution was varied successively, the physico-chemical properties of the membrane changed drastically at a certain valueC _t . The relationships between the electrical response and the external stimuli studied are as follows: (1) The membrane potential oscillates spontaneously in a spikelike fashion when the concentration of the external solution is suddenly changed. (2) The current through the membrane oscillates in spikelike fashion for a duration of about 50 msec when the constant external voltage, V larger than a certain value V _c , is applied across the membrane. (3) The electric resistance sharply decreases, and a kind of action potential similar to that observed in living tissues is produced when a short rectangular electric stimulus, whose magnitude is higher than a critical value V _p , is applied. (4) If a hydrostatic pressure difference across the membrane is applied with appropriate salt conditions, the value of the membrane potential varies with time, as in the case of (3). The observed changes in emf and electric resistance are discussed in connection with the conformational change of DOPH molecules in the membrane.     

Molecular dynamics simulation of liquid water under the influence of an external electric field

Molecular dynamics simulations of liquid water were performed at 258K and a density of 1.0?g/cm³ under various applied external electric field, ranging 0～10¹⁰?V/m. The influence of external field on structural and dynamical properties of water was investigated. The simple point charge (SPC) model is used for water molecules. An enhancement of the water hydrogen bond structure with increasing strength of the electric field has been deduced from the radial distribution functions and the analysis of hydrogen bonds structure. With increasing field strength, water system has a more perfect structure, which is similar to ice structure. However, the electrofreezing phenomenon of liquid water has not been detected since the self-diffusion coefficient was very large. The self-diffusion coefficient decreases remarkably with increasing strength of electric field and the self-diffusion coefficient is anisotropic.     

Control of green mould of citrus by using Trichoderma harzianum,humic acid or garlic

Penicillium digitatum, an aggressive fungus causes post-harvest decay of mandarin sweet orange and Washington navel. In vitro Trichoderma harzianum or humic acid (HA) or powdered cloves of garlic caused inhibition of fungal growth of isolates P₁ and P₂. Under storage conditions, the fruit citrus is protected by using T. harzianum with standard volume 2.0?ml (9.6?×?10⁶?conidia/ml) and application 24?h before inoculation reduces disease incidence and disease severity after seven?days from inoculation with P. digitatum spore suspension (1.0?×?10⁶?spores/ml) compared to control. Spraying the fruit citrus by standard volume of 2.0?ml of either HA or powder cloves of garlic 1% on each fruit 24?h before inoculation reduces disease incidence and disease severity after seven?days from inoculation with P. digitatum (1.0?×?10⁶ spores/ml) compared to control. The lowest percentage of disease incidence and disease severity were associated with powder of cloves garlic and followed by HA and T. harzianum during two growing seasons compared with the untreated and control.     

Potassium Channels in Eremosphaera viridis: Modulation of Channel Opening,Conductance and Inhibition*

I/V relationships were performed by the voltage clamp technique in the sphaerical green alga Eremosphaera viridis de Bary. We focused on the course of the transient potential (TP) found in light-off experiments when specific potassium channels open. I/V measurements done during this period show a N-shaped curve. The shape depended on external potassium. TPs could be released by light-off and by addition of barium, strontium, or α-naphthyl phosphate. We calculated the number of specific potassium channels to be between 1750 and 34 825 channels per cell. Barium (1 mol × m^?3) and tetraethylammonium (10 mol × m^?3) inhibited TPs. I/V relationships demonstrated, when N-shaped, that potassium channels start to close at voltages more negative than ?195 mV (0.1 mol × m^?3 K⁺), ?160 mV (1 mol × m^?3 K⁺) and ?148 mV (10 mol × m^?3 K⁺). In the region of ?300 mV conditions similar to those at rest are reached. External sodium suppressed the development of N-shaped I/V relationships and reduced the membrane conductance during a TP between 8 % and 29 %. This indicates an influence of external sodium on potassium channels.     

Studies on induced mutants with reference to species relationships in some tetraploid Triticums

Summary A mutational analysis of five tetraploid species of Triticum was carried out to study different types of systematic mutants. Rare systematic mutants viz., free-threshing mutants and the timopheevioid mutant of T. dicoccum, polonicum-type mutants of T. durum, turgidum-type mutants of T. carthlicum and durum-type mutants of T. turgidum and polonicum, which occurred with consistently high frequencies, are discussed in relation to the phylogenetical interrelationships of these species. The study supports Mac Key's (1966) proposal that all these species would be best grouped as sub-species of Triticum turgidum.A part of the Ph. D. Thesis submitted to Indian Agricultural Research Institute, New Delhi by M. V. R. Prasad under the Guidance of Dr. M. S. Swaminathan.     

Influence of electric fields on photophobic reactions in blue-green algae

The effect of external electric fields on photo-accumulations of Phormidium uncinatum in light traps has been studied. 1. In direct current fields the phobic reaction of trichoms leaving the light field is not impaired if a voltage of 2.5 V is not exceeded. With voltages between 3 and 7 V the trichoms are motile, but phobic reactions are cancelled, provided the organisms are oriented more or less parallel to the electric field lines. Higher voltages cause the algae to die within minutes. 2. Only alternating current fields of very low frequencies (less than or equal 10(-3) Hz) have similar effects. Sine waves are more effective than triangular ones, but less than square waves. A hypothesis is proposed according to which sensory transduction of photophobic reactions in blue-green algae is mediated by changes in the endogenous membrane potential. This potential might be interfered with by the application of an external electric field, thus inhibiting photophobic reactions.     

Spontaneous action potentials and resting potential shifts in fertilized eggs of the tunicate Clavelina

Electrical activity in the fertilized egg of the tunicate Clavelina was studied with microelectrode recording and voltage clamp techniques. The resting potential could assume either of two stable values (approximately ?70 or ?30 mV) and could be shifted between these values by direct current stimulation. Spontaneous shifts between two stable resting potentials were also seen. Egg cells produced action potentials spontaneously and in response to depolarizing stimuli. Inward currents were carried by both Na and Ca ions and a prominent outward potassium current was seen with depolarization to voltages above ?15 mV. The steady-state current-voltage relationship (I–V curve) of the membrane showed two voltages where the net membrane current equaled zero: approximately ?35 and ?70 mV. Between these two voltages, membrane current was inward and carried by noninactivating Na and Ca currents. Inward rectification, which was blocked by external Rb, occurred at voltages below ?70 mV. The voltage dependence of inward rectification is thought by the authors to be important for establishing the more negative resting potential; it is also thought the presence of inward current which does not inactivate completely at voltages more negative than about ?20 mV is an important determinant of the more depolarized resting potential.     

Production of intergeneric hybrid between dwarfing polish wheat (<Emphasis Type="Italic">Triticum polonicum</Emphasis> L.) and <Emphasis Type="Italic">Aegilops tauschii</Emphasis> Cosson. with reference to wheat origin

Dwarfing polish wheat is a dwarfing accession of Triticum polonicum L. from Xinjiang of China. In the present study, the artificial hybridization between dwarfing polish wheat and two accessions of Aegilops tauschii Cosson. (AS60 and AS65) was carried out, and the F₁ hybrids were obtained successfully without using embryo rescue techniques for the first time. The crossabilities of hybrids T. polonicum × Ae. tauschii (AS60) and T. polonicum × Ae. tauschii (AS65) were 1.67% and 0.60% respectively. Only the hybrids of T. polonicum × Ae. tauschii (AS60) germinated well, and 24 F₁ hybrid plants were obtained. All the F₁ hybrid plants grew vigorously, and the morphological traits were similar to bread wheat. The F₁ plants had some obvious traits inherited from T. polonicum and Ae. tauschii and were completely sterile. Chromosome pairing in the hybrid was characterized by a large number of univalents, with an average of 20.56 and 0.22 bivalents per PMC, and no ring bivalents and multivalents were observed. Furthermore, the potential value of the F1 hybrids between T. polonicum and Ae. tauschii for studying wheat origin and breeding are discussed. The article is published in the original.     

Aerobic training reduces oxidative stress in skeletal muscle of rats exposed to air pollution and supplemented with chromium picolinate

Objective: The purpose of this study was to investigate the effects of chromium picolinate (CrPic) supplementation associated with aerobic exercise using measures of oxidative stress in rats exposed to air pollution.

Methods: Sixty-one male Wistar rats were divided into eight groups: residual oil fly ash (ROFA) exposure and sedentary (ROFA-SED); ROFA exposure, sedentary and supplemented (ROFA-SED-CrPic); ROFA exposure and trained (ROFA-AT); ROFA exposure, supplemented and trained (ROFA-AT-CrPic); sedentary (Sal-SED); sedentary and supplemented (Sal-SED-CrPic); trained (Sal-AT); and supplemented and trained (Sal-AT-CrPic). Rats exposed to ROFA (air pollution) received 50?µg of ROFA daily via intranasal instillation. Supplemented rats received CrPic (1?mg/kg/day) daily by oral gavage. Exercise training was performed on a rat treadmill (5×/week). Oxidative parameters were evaluated at the end of protocols.

Results: Trained groups demonstrated lower gain of body mass (P?P?P?P?=?.0014), although CAT activity did not differ among groups (P?=?.4487).

Conclusion: Air pollution exposure did not lead to alterations in oxidative markers in lungs and heart, and exercise training was responsible for decreasing oxidative stress of the gastrocnemius.     

In vitro evaluation of six fungicides on radial mycelial growth and regrowth of Fusarium pallidoroseum isolated from castor (Ricinus communis) in Samaru,Nigeria

Six fungicides at three rates (1.5x, 1.0x and 0.5x mg a.i/ml) were evaluated on radial growth and and regrowth of mycelia of Fusarium pallidoroseum isolated from castor (Ricinus communis) in vitro. It was observed that the fungicides (Benomyl, Benomyl + Thiram, Mancozeb, Metalaxyl-m + Thiomethoxan + Difenconazol, Tricyclazole and Carbendazim + Mancozeb) at all the concentrations tested inhibited mycelial growth and regrowth of the fungus. Benomyl, Benomyl + Thiram and Tricyclazole completely inhibited mycelia growth of fungus at 1.5x, 1.0x and 0.5x mg a.i/ml. Metalaxyl-m + Thiomethoxan + Difenconazole, Carbendazim + Mancozeb partially inhibited radial growth and re-growth of mycelia only at 1.5x mg a.i/ml, not at 1.0x and 0.5x mg a.i/ml. The inhibitory effect of all the fungicides on mycelia growth and re-growth was greatest at 1.x5 mg a.i/ml.     

Recombination in Polymer:Fullerene Solar Cells with Open‐Circuit Voltages Approaching and Exceeding 1.0 V

Polymer:fullerene solar cells are demonstrated with power conversion efficiencies over 7% with blends of PBDTTPD and PC₆₁BM. These devices achieve open‐circuit voltages (V_oc) of 0.945 V and internal quantum efficiencies of 88%, making them an ideal candidate for the large bandgap junction in tandem solar cells. V_oc’s above 1.0 V are obtained when the polymer is blended with multiadduct fullerenes; however, the photocurrent and fill factor are greatly reduced. In PBDTTPD blends with multiadduct fullerene ICBA, fullerene emission is observed in the photoluminescence and electroluminescence spectra, indicating that excitons are recombining on ICBA. Voltage‐dependent, steady state and time‐resolved photoluminescence measurements indicate that energy transfer occurs from PBDTTPD to ICBA and that back hole transfer from ICBA to PBDTTPD is inefficient. By analyzing the absorption and emission spectra from fullerene and charge transfer excitons, we estimate a driving free energy of –0.14 ± 0.06 eV is required for efficient hole transfer. These results suggest that the driving force for hole transfer may be too small for efficient current generation in polymer:fullerene solar cells with V_oc values above 1.0 V and that non‐fullerene acceptor materials with large optical gaps (>1.7 eV) may be required to achieve both near unity internal quantum efficiencies and values of V_oc exceeding 1.0 V.     

The optimal concentrations of Purpureocillium lilacinum and jasmonic acid in controlling Meloidogyn javanica on tomato

Abstract

Management of root-knot nematodes (Meloidogyne spp.) is too difficult and is mainly based on chemicals. Synthetic nematicides contaminate the environment and endanger the human health, so scientists have been tried to find a new alternative safe method for nematode control. Activating plant immunity system in integration with biological control seems promising. Here, we tried to control Meloidogyne javanica on tomato plants by simultaneous application of jasmonic acid (JA), as a defence inducer, and Purpureocillium lilacinum (Pl) as a biocontrol agent. A factorial experiment was devised with two main factors each in four levels. The concentration of JA and Pl was 0, 0.5, 1, and 1.5?mM and 0, 10³, 10⁶, and 10⁹ spore ml^?1 suspension, respectively. Cadusafos was used as positive control. Tomato growth characteristic as well as nematode reproduction traits were evaluated 8 weeks after being grown in a greenhouse. The data were analysed by a custom response surface regression model. Increase in concentration of main factors led to increase in plant growth and decrease in nematode reproduction. JA at 1.5?mM concentration could control nematode the same as cadusafos regardless to fungus concentration. Simultaneous application of JA and Pl reciprocally increase the effect of each factor. The lowest concentration of P. lilacinum and JA for achieving the compromise best plant growth and lowest nematode reproduction were 1.5?mM JA and 40.51?×?10⁶ conidia of P. lilacinum ml^?1 suspension.     

Cooling ranges for urban heat mitigation: continuous cooling effects along the edges of small greenspaces

This study assessed the cooling ranges of small greenspaces (SGs) along the edges of surrounding areas and identified the spatial cooling distance threshold. Five SGs in a natural preserved public area located in College Station, Texas, USA, and a reference site (Rf) were selected for this study. Air temperature data collection took six rounds from fall to early summer. In each round air temperature was collected three times during a day (i.e., 10 h, 13 h, and 16 h). Temperature sensing units (TVCs) and loggers recorded air temperature every second via a transect survey. The cooling distance was determined according to each SG’s radius: (1) the centroid of the SG (GC), (2) the edge of the SG (GE), (3) 1.25 times the radius away from the GC (1.25R), and (4) 1.5 times the radius away from the GC (1.5R). Our findings showed the SGs’ cooling effect (?T_Rf?i) surpassed their edges in general. The cooling degrees at the GC were higher and dropped continuously from the GE to 1.25R ending with 1.5R showing the lowest. In fall, the SGs’ mean cooling degree exceeded 9.24% at 1.5R compared to Rf. In early summer, the SGs’ mean cooling effects decreased significantly while showing a very small difference between the measurement points. Our findings contribute to uncovering some specific design features with SGs to cooling down cities by applying advanced technology. Our findings will help designers, planners, researchers, and local government officials by providing an optimal landscape planning and design guide for mitigating urban heat.

     

Quartz Sand as an Adsorbent for Purification of Extracellular Glucose Oxidase from Penicillium funiculosum 46.1

A procedure for purification of extracellular glucose oxidase (GO, EC 1.1.3.4) from a filtrate of culture liquid (CLF) of the fungus Penicillium funiculosum 46.1 has been developed using alluvial quartz sand as an adsorbent. Modifying the sand by changing the charge and polarity did not lead to a significant increase in its adsorption capacity towards GO. The effectiveness of sand and aluminum oxide used as adsorbents for GO isolation from CLF has been compared. Glucose oxidase isolated from CLF by adsorption on sand exhibited a greater catalytic activity than enzyme preparations obtained by column chromatography on CLF. Glucose oxidase from P. funiculosum 46.1 was adsorbed on sand more effectively than on aluminum oxide. It is concluded that sand may be used for fractionation of partially purified GO.