Slight Stimulation Research Articles

Heavy metal accumulation and tolerance of energy grass (Elymus elongatus subsp. ponticus cv. Szarvasi-1) grown in hydroponic culture

Phytoremediation is a plant based, cost effective technology to detoxify or stabilise contaminated soils. Fast growing, high biomass, perennial plants may be used not only in phytoremediation but also in energy production. Szarvasi-1 energy grass (Elymus elongatus subsp. ponticus cv. Szarvasi-1), a good candidate for this combined application, was grown in nutrient solution in order to assess its Cd, Cu, Ni, Pb and Zn accumulation and tolerance. Its shoot metal accumulation showed the order Pb < Ni < Cu ∼ Cd < Zn. In parallel with this, Pb and Ni had no or very little influence on the growth, dry matter content, chlorophyll concentration and transpiration of the plants. Cu and Cd treatment resulted in significant decreases in all these parameters that can be attributed to Fe plaque formation in the roots suggested by markedly increased Fe and Cu accumulation. This came together with decreased shoot and root Mn concentrations in both treatments while shoot Cu and Zn concentrations decreased under Cd and Cu exposure, respectively. Zn treatment had no effect or even slightly stimulated the plants. This may be due to a slight stimulation of Fe translocation and a very efficient detoxification mechanism. Based on the average 300 mg kg⁻¹ (dry mass) Zn concentration which is 0.03% of the shoot dry mass the variety is suggested to be classified as Zn accumulator.

Decoding Pain from the Facial Display of Patients with Dementia: A Comparison of Professional and Nonprofessional Observers

Patients with dementia, whose ability to provide self-report of pain is often impaired, are in crucial need of observers who can detect and judge the patients' pain-indicative behaviors appropriately, in order to initiate treatment. The facial display of pain promises to be especially informative for that purpose. The major aim of the study was to investigate, whether facial pain displays of patients with dementia can be as easily interpreted as facial displays of individuals without cognitive impairment and whether nurses have learned-through their professional training and work experience-to better read the facial display of pain compared with a control group. For that purpose, 21 nurses and 21 age-matched controls watched 120 video clips, showing facial expressions of young and old individuals with and without dementia during slight and moderate noxious stimulation. After each clip, subjects were asked to rate how much pain the observed individual might have experienced. The observer ratings did not differ between nurses and controls as regards pain level and concordance. On the other hand, level and concordance of the pain judgments were strongly influenced by the cognitive status, age, and gender of the observed individuals, with higher and more accurate pain judgments for older and for female individuals. Without further contextual information, "professional" observers do not show a superior competence in inferring pain in others by reading their facial display. Therefore, additional training seems needed to reliably prevent that pain goes unnoticed in patients with dementia.

Ecotoxicological analysis of fly ash and rice-straw black carbon on Microcystis aeruginosa using flow cytometry

Black carbon (BC) has a strong affinity for hydrophobic organic compounds (HOCs), and it is a potential material to control HOCs pollution in aquatic ecosystems. Here, flow cytometry (FCM) was used to evaluate the ecotoxicological effect of fly ash, rice-straw ash, and their acid-demineralised products on the growth of Microcystis aeruginosa. It was found that the BCs had little negative effect on cyanobacteria, when the content of BCs was not above 1mgml−1. However, higher doses of BCs (>2mgml−1) had an obvious negative effect on cell density and esterase activity, especially for BCs with acid treatment, which greatly inhibited cell density caused by its high adsorptivity for cyanobacteria. The BCs had little impact on the fluorescence intensity, only with a slight stimulation in later period, so the fluorescence intensity was a less sensitive indicator than cell density and esterase activity. Considering ecotoxicological effect of BCs on the algae, the application concentration of BCs for HOCs pollution control as in situ remediation material would better not exceed 1mgml−1.

INFLUENCE OF SOME MICROELEMENTS ON BASIDIOMYCETES OXIDOREDUCTASES ACTIVITY

The article is devoted to the influence of some microelements on the growth and activity of antioxidant oxidoreductase of basidiomycetes. The objects of the study were strains – active producers of oxidoreductases: Agrocybe cylindracea 167; Pleurotus ostreatus P-208 and Fistulina hepatica Fh-08. The weighting method of determination of accumulation of absolutely dry biomass was used to study the influence of some microelements on the growth. Catalase, peroxidase and superoxide dismutase activity and protein content of mycelium and culture filtrate was determined by spectrophotometric methods, and the specific activity of enzymes were calculated. A significant effect of Fe2+, Cu2+, Zn2+ and Mn2+ on the level of accumulation of absolutely dry biomass, catalase, peroxidase and superoxide dismutase activity was estimated. It was found that the stimulation of peroxidase activity in mycelia and culture filtrate of the strains P. ostreatus P-208 and F. hepatica Fh-08 caused by the addition of Fe2+ in the concentration of 8 and 1.6 mmol / l, and the stimulation of their catalase activity caused by the addition of Cu2+ and Mn2+ in the concentration of 8 mmol / l. Increased catalase activity of strain A. cylindracea is 167 caused by amending Cu2+ and Zn2+ in the concentration of 8 mmol / l in the medium. There was a slight stimulation of superoxide dismutase activity of the strains of basidiomycetes caused by addition of ferrous sulphate in the nutrient medium. The results of the study showed the relationship between the composition of culture media and the structure, function and localization of enzymes and their interaction.

Investigation of Nonlinear Pupil Dynamics by Recurrence Quantification Analysis

Pupil is controlled by the autonomous nervous system (ANS). It shows complex movements and changes of size even in conditions of constant stimulation. The possibility of extracting information on ANS by processing data recorded during a short experiment using a low cost system for pupil investigation is studied. Moreover, the significance of nonlinear information contained in the pupillogram is investigated. We examined 13 healthy subjects in different stationary conditions, considering habitual dental occlusion (HDO) as a weak stimulation of the ANS with respect to the maintenance of the rest position (RP) of the jaw. Images of pupil captured by infrared cameras were processed to estimate position and size on each frame. From such time series, we extracted linear indexes (e.g., average size, average displacement, and spectral parameters) and nonlinear information using recurrence quantification analysis (RQA). Data were classified using multilayer perceptrons and support vector machines trained using different sets of input indexes: the best performance in classification was obtained including nonlinear indexes in the input features. These results indicate that RQA nonlinear indexes provide additional information on pupil dynamics with respect to linear descriptors, allowing the discrimination of even a slight stimulation of the ANS. Their use in the investigation of pathology is suggested.

Characterization of the novel xylanase from the thermophilic Geobacillus thermodenitrificans JK1

Thermophilic strain JK1 was isolated from compost using xylan as a single carbon source. On the basis of 16S rRNA gene phylogenetic analysis and spo0A gene sequence similarity analysis, strain JK1 was identified as Geobacillus thermodenitrificans strain. During the exponential culture growth, the strain JK1 was found to produce the single xylan degrading enzyme -45 kDa in size. Xylose was not an inducer of this xylanase. Cloning, expression and characterization of the recombinant xylanase were performed. Xylanase of G. thermodenitrificans JK1 was cellulase-free; pH and temperature optimums were found to be 6.0 and 70 degrees C, respectively. The metal ions Na+, K+, Ca2+, and Co2+ showed partial inhibition of the activity, while Mn2+ had slight stimulating effect on the enzymatic activity. Recombinant xylanase was thermostable over the temperature range of 55-70 degrees C. It presented the highest stability after incubation at 55 degrees C for 60 min showing 84% residual activity. 50% residual activity was revealed after incubation at 60 degrees C for 60 min as well as at 65 and 70 degrees C for 30 min. Results of the thermostability experiments showed xylanase of JK1 having quite low thermostability when compared with the respective enzymes of the other geobacilli.

An insight into the mechanisms of nanoceria toxicity in aquatic photosynthetic organisms

The effect of nanoceria on two aquatic photosynthetic organisms of ecological relevance, a green alga and a cyanobacterium, is reported. The main bioenergetic process of these organisms, photosynthesis, was studied by measuring both oxygen evolution and chlorophyll a fluorescence emission parameters. Nanoceria significantly inhibited photosynthesis in the cyanobacterium in the entire range of concentrations tested (0.01–100mg/L), while a dual effect of nanoceria was found in the green alga with slight stimulation at low concentrations and strong inhibition at the highest concentrations tested. Chlorophyll a fluorescence experiments indicated that nanoceria had a significant impact on the primary photochemical processes of photosystem II. The primary cause of the observed photosynthetic inhibition by nanoceria is an excessive level of ROS formation; the results indicated a strong generation of reactive oxygen species (ROS) which caused oxidative damage, as evidenced by lipid peroxidation in both photosynthetic organisms. It is proposed that nanoceria can increase the production of hydrogen peroxide (a normal ROS by-product of light-driven photosynthesis) in both the green alga and the cyanobacterium; through an oxidative reaction, these ROS cause lipid peroxidation, compromising membrane integrity and also seriously impairing photosynthetic performance, eventually leading to cell death.

Agricultural residues as potential substrates for production of xylanase from alkali-thermotolerant bacterial isolate

Abstract Xylanolytic Bacillus pumilus SS1 grew well at highly alkaline pH (9–11) and at moderately high temperature (25–55 °C) and successfully utilized wheat bran as the sole carbon source and produced considerable titer of xylanase. Maximum enzyme production occurred at medium pH 8 and at 45 °C. The enzyme purified (2.97-fold) with ammonium sulfate fractionation and carboxymethyl sephadex chromatography, showed molecular weight of 25 kDa, low Km (2.7 mg/ml) and reasonably good Vmax (36 μmol/mg/min). Enzyme showed maximum activity at pH 6–8, and at 40–50 °C. Enzyme was inhibited by HgCl2, CoCl2, MnSO4, MgCl2, phenylmethylsulphonylfluoride and CaCl2, while FeCl2 caused slight stimulation.

Differential behavioral profiling of stimulant substances in the rat using the LABORAS™ system

Preclinical testing requires rapid and reliable evaluation of the main in vivo effects of novel test substances usually in rodents. Nevertheless, the techniques primarily used up to now involve either automated measurement of motor activity or direct observation of behavioral effects by extensively trained investigators. The advantages of these approaches are respectively high-throughput and comprehensive behavioral assessment. Nevertheless, motor activity is only one aspect of animal behavior and it cannot predict the full neurobehavioral profile of a substance, whereas direct observation is time-consuming. There is thus a need for novel approaches that combine the advantages of both automatic detection and comprehensive behavioral analysis. In the present study, we used the LABORAS™ system to analyze motor and non-motor behavior in rats administered various stimulant substances with or without known psychotomimetic properties or abuse liability (amphetamine, cocaine dizocilpine (MK-801), ketamine, modafinil and nicotine).The data show that LABORAS™ clearly detects the stimulating effects on motor behaviors of amphetamine, cocaine, dizocilpine and ketamine in a dose- and time-dependent manner. Differential effects of these test substances on non-motor behaviors, such as grooming, eating and drinking could also be detected. Nicotine displayed only slight stimulating effects on locomotion, whereas modafinil was virtually without effect on the behaviors evaluated by the system.These data with different stimulant substances suggest that LABORAS™ presents an advantage over classical methods performing automated measurements restricted to locomotion. Furthermore, the procedure is considerably more rapid than behavioral observation procedures. Characterization of the behavioral profile of test substances using LABORAS™ should therefore accelerate preclinical studies. In addition, the multi-faceted parameters measured by LABORAS™ permit a more detailed comparison of the behavioral profiles of novel substances with standard reference substances, thereby providing important indicators for orienting further substance evaluation and supporting drug development.

The Evaluation of Heavy Metal Toxicity in Plants Using the Biochemical Tests

The evaluation of the toxicity and stress caused by heavy metals on plants is very important part of the phytoremediation research. Several physiological parameters can be used to assess the heavy metalinduced stress such as germination, plant growth and biomass production, photosynthetic pigments, antioxidant enzymes or antioxidants. Published results of measured physiological parameters in plants exposed to metals were characterized from of the negative effects of metals point of view and compared with the experimental study of the metal (Cu, Cd, Zn) toxicity in flax (Linum usitatissimum) and China aster (Callistephus chinensis) using the biochemical tests under the laboratory conditions. The germination and biomass production of C. chinensis significantly decreased with the increase of metal concentration which is considered a very typical response, however in L. usitatissimum slight stimulation of germination and biomass production at low metal content was observed. From the two studied plants C. chinensis expressed typical symptoms of the heavy metal toxicity including the decrease of total chlorophyll, chlorophylls a, b. On the contrary, heavy metal ions affected positively the physiological parameters of L. usitatissimum when low metal concentrations were added for example slight increase of the chlorophyll concentration in leaves was recorded. The decrease of the chlorophyll content was observed only at the high metal content. On the other hand, the typical response of plants on the heavy metal stress - the increase in peroxidase activity - was observed only for L. usitatissimum but not for C. chinensis that in all other tests showed significant toxicity symptoms. So if only one physiological parameter would be considered incorrect interpretation could be concluded. With the increase of phytoremediation practical applications the more systematic tests of heavy metal stress are necessary to help scientists working in that field correctly interpret their results and understand the plant behaviour.

Biocompatibility and biodegradability of implantable drug delivery matrices based on novel poly(decane-co-tricarballylate) photocured elastomers

Visible light photo-cross-linked biodegradable amorphous elastomers based on poly(decane- co-tricarballylate) (PDET) with different cross-linking densities were synthesized, and their cytotoxicity, biocompatibility, and biodegradability were reported. Cytotoxicity of PDET extracts of the elastomers was assessed for mitochondrial succinate dehydrogenase activity by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT assay) and inhibition of [3H] thymidine incorporation into DNA of epithelial cells. The in vivo biocompatibility and biodegradability were determined by subcutaneous implantation of PDET microcylinders in 25 male Sprague–Dawley rats over a period of 12 weeks. The in vivo changes in physical and mechanical parameters of the implants were compared with those observed in vitro. The treated epithelial cells revealed no signs of cytotoxicity, and the elastomer degradation products caused only a slight stimulation to both mitochondrial activity and DNA replication. The implants did not exhibit any macroscopic signs of inflammation or adverse tissue reactions at implant retrieval sites. The retrieved implanted microcylinders maintained their original geometry and extensibility in a manner similar to those observed in vitro. These new elastomers have excellent biocompatibility and are considered promising biomaterials for controlled drug delivery and tissue engineering applications.

Biosynthesis, purification and characterization of β-fructofuranosidase from Bifidobacterium longum KN29.1

Bifidobacterium longum KN29.1 exhibits greater β-fructofuranosidase activity than two Bifidobacterium animalis strains with highest activity observed when B. longum KN29.1 was grown on fructose. Properties of the native β-fructofuranosidase from B. longum KN29.1 and recombinant β-fructofuranosidase were identical. The molecular mass of the purified β-fructofuranosidase was approximately 67kDa as determined by SDS-PAGE. Its isoelectric point was 4.6. The enzyme was stable at pH 5.7–9.1 and the temperature up to 45°C. It was optimally active in Actilight® 950P and sucrose hydrolysis at pH 6.0–6.2 while the optimum temperature of these processes was 50°C and 37–45°C, respectively. In the presence of Cu2+, Ag+, Hg+ ions and p-chloromercuribenzoic acid (1mM) B. longum KN29.1 β-fructofuranosidase activity was completely inhibited, its slight stimulation was observed in solutions containing Mn2+ (1mM). This enzyme showed higher affinity for nystose (Km 1.2±0.15mM) and 1-kestose (Km 4.6±0.2mM) than for sucrose (Km 29.4±1.5mM). It catalyzed the hydrolysis of sucrose, 1-kestose and inulin at the relative activities of 100, 251.7±7.36 and 62.2±1.15%, respectively. TLC and HPLC analysis demonstrated that the enzyme released β-fructofuranose from the non-reducing end of inulin and fructooligosaccharides. The comparative analysis of known crystallographic structures from the glycoside hydrolase family 32 (GH32) available in databases was performed and a three-dimensional model of B. longum KN29.1 β-fructofuranosidase was proposed. The modeled structure was compared to the structure of B. longum KN29.1 β-fructofuranosidase which was solved by X-ray crystallography and published after the first version of this manuscript had been submitted. The described B. longum KN29.1 enzyme is a monomeric protein consisting of 2 domains: 5-bladed β-propeller catalytic domain and β-sandwich domain.

Dimethoate-induced oxidative stress and DNA damage in Oncorhynchus mykiss

The present study was conducted in order to investigate pro-oxidant activity of dimethoate in liver and brain tissues following sublethal pesticide exposure for 5, 15 and 30d by using SOD, GPx, CAT enzyme activities and lipid peroxidation as biomarkers as well as DNA damaging potential via detecting% Tail DNA, Tail moment and Olive tail moment as endpoints in erythrocytes of Oncorhynchus mykiss in an in vitro experiment. Antioxidant enzyme activities were found to elicit two staged response which was an initial induction followed by a sharp inhibition in liver tissue while a sustained increase in GPx activity and slight stimulation in SOD activity were detected in brain tissue. Lipid peroxidation showed an ascending pattern throughout the exposure period in both tissues and a decreasing trend was determined in tissue protein levels which was proved to be positively correlated with duration. Similar findings were obtained from outcomes preferred to quantify DNA damage and TM was decided to reflect the extent of damage more sensitively because of determined positive correlation with concentrations applied. Considering these results, it can be concluded that oxidative stress condition evoked by dimethoate could not be responded effectively and genotoxic nature of pesticide was proven by determined clastogenic effect possibly via being an alkylation agent or stimulating the production of reactive species.

Effect of tooth pulp and periaqueductal central gray stimulation on the expression of genes encoding the selected neuropeptides and opioid receptors in the mesencephalon, hypothalamus and thalamus in rats

Nociceptive stimulation has been considered to affect the expression of genes encoding endogenous neuropeptides and their receptors. The effect of electric stimulation of the tooth pulp and/or periaqueductal gray (PAG) in rats on mRNA levels of the selected neuropeptides and opioid receptors (ORs) was investigated in comparison with control group, without stimulation. The levels of mRNA for the selected neuropeptides: galanin (GAL), vasopressin (AVP), oxytocin (OT), substance P (SP), somatostatin (SOM), vasoactive intestinal peptide (VIP), endomorphin-2 (EM-2), and opioid receptors: MOR, DOR and KOR in mesencephalic, hypothalamic and thalamic tissues were determined by real-time PCR. It was demonstrated that in the control group expression of the tested neuropeptides was at a very low level in the mesencephalon and thalamus, but at the higher level in the hypothalamus. The highest expression of ORs was observed in the mesencephalon. Nociceptive tooth pulp stimulation had the strongest effect in the hypothalamus, elevating mRNA levels of all tested neuropeptides except SOM. Electric stimulation of PAG either did not change or down-regulated mRNA levels of the neuropeptides in the cerebral structures. Simultaneous stimulation of PAG and tooth pulp either did not affect mRNA levels of the investigated neuropeptides or caused their slight decrease versus tooth pulp stimulation. The noxious stimulation of tooth pulp increased also the levels of OR mRNAs, while stimulation of PAG had the opposite effect. The above results demonstrated that tooth pulp stimulation significantly up-regulated the mRNA levels for a number of neuropeptides and all three types of ORs in the rat brain, which would result in more potent antinociception. In contrast, PAG stimulation down-regulated the mRNA levels of several neuropeptides and ORs in the cerebral tissues, which would cause decreased synthesis of ORs. The obtained results represent a new insight into the mechanism of orofacial pain.

Nicotinamide metabolism in ferns: Formation of nicotinic acid glucoside

The metabolic fate of [carbonyl-(14)C]nicotinamide was investigated in 9 fern species, Psilotum nudum, Angiopteris evecta, Lygodium japonicum, Acrostichum aureum, Asplenium antiquum, Diplazium subsinuatum, Thelypteris acuminate, Blechnum orientale and Crytomium fortune. All fern species produce a large quantity ofnicotinic acid glucoside from [(14)C]nicotinamide, but trigonelline formation is very low. Increases in the release of (14)CO(2) with incubation time was accompanied by decreases in [carboxyl-(14)C]nicotinic acid glucoside. There was slight stimulation of nicotinic acid glucoside formation by 250mM NaCl in mature leaves of the mangrove fern, Acrostichum aureum, but it is unlikely that this compound acts as a compatible solute. Nicotinamide and nicotinic acid salvage for pyridine nucleotide synthesis was detected in all fern species, although this activity was always less than nicotinic acid glucoside synthesis. Predominant formation of nicotinic acid glucoside is characteristic of nicotinic acid metabolism in ferns. This reaction appears to act as a detoxication mechanism, removing excess nicotinic acid.

The combined effect of anthracene and cadmium on photosynthetic activity of three Desmodesmus (Chlorophyta) species

Individual toxicity of heavy metals (HM) and polycyclic aromatic hydrocarbons (PAH) to plants living in water bodies is well-documented. In view of frequent joint occurrence of these compounds in the environment, plants are subjected to damage from their combined action. Cadmium and anthracene can generate production of reactive oxygen species (ROS). We have recently detected elevated activity of Fe- and Mn-SOD isoforms, indicating chloroplast and mitochondrion as the main sites of combined toxicity of HM and PAH. In the present paper, short-term (1–24h) experiments on the mechanism of combined toxicity of anthracene and cadmium to the photosynthesis of three Desmodesmus species are reported. Inhibition, stimulation or no effect on the oxygen evolution was observed following the treatment with the contaminants when applied either separately or jointly. The response pattern was both strongly species- and time-dependent. In contrast, the photosynthetic activity of cells, expressed by chlorophyll fluorescence parameters, was substantially unaffected, since no effect or, in several cases, a slight stimulation of PS II quantum efficiency (Φ PS II) were noted. A characteristic relationship between the SOD activity and the qN values was observed. The treatment of Desmodesmus cells with anthracene or cadmium had either no effect or slightly enhanced either the SOD activity or the qN value, whereas the mixture of the contaminants resulted in a multifold increase in both the SOD activity and the qN values. The results suggest that chloroplasts of algae are well protected against the combined action of the two contaminants the toxicity of which should be attributed to nucleocytoplasmic compartments and reproductive processes of the cell cycle.

Dependency of nociception facilitation or inhibition after periaqueductal gray matter stimulation on the context

Anxiety and/or fear can alter the nociceptive response in humans and animals. Slight stimulation of the dorsal periaqueductal gray matter (DPAG) produced anxiety/fear-related behaviour and hyponociception in escapable, non-anxiogenic nociceptive models. Our aim was to investigate the role of the DPAG in models of persistent, anxiogenic nociception. GLY (1, 10, 20, and 80 nmol/0.3 μl/60 s) was injected into the DPAG of rats, 5 min before formalin (2%/50 μl) injection either into the knee-joint or hind paw. In the knee-joint incapacitation test, GLY caused hypernociception at lower doses and hyponociception at higher doses. In the paw shacking test, GLY produced only hypernociception with the higher dose. Co-injecting GLY with 7-chlorokynurenic acid (7-CLK) or (+/−)-3-amino-1-hydroxy-2-pyrrolidone (HA-966) completely prevented the GLY effects in incapacitation and paw shacking tests, respectively. GLY injections outside the periaqueductal gray matter (PAG) did not change the nociception. Behavioural analysis indicated that formalin paw injection produced higher stress signals than knee-joint injection, as diminished exploratory behaviour, and stereotypy. The results suggest that activation of the DPAG through the GLY B/NMDA receptor is able to produce either facilitation or inhibition of nociception depending on the nociceptive context.

Affinity electromembrane: Electrically facilitated adsorption

Previous methods for improving adsorption capacity and rate of affinity membrane are through enhancing ligand content. However, the high ligand density does not always translate into high ligate capacity. Herein, a novel strategy for affinity membrane to improve adsorption capacity and rate is introduced, and an affinity membrane with electrical conductivity, which we termed “affinity electromembrane”, is reported for the first time. Adenosine-5′-triphosphate (ATP) and hemoglobin are chosen as model ligand and ligate, respectively. The ATP-immobilized affinity electromembrane is fabricated by synthesizing conducting polymers polypyrrole onto porous polycarbonate track-etch membrane using ATP as both ligand and dopant. The as-prepared affinity electromembrane owns good pore structure, uniform conductivity, and excellent selectivity for hemoglobin. By applying a slight electrical stimulation (3–9 μA) to the affinity electromembrane, the hemoglobin adsorption capacity and rate are greatly facilitated. In addition, the affinity electromembrane has the unique performance of replacing the ligand on the membrane, which greatly extends the life-time of affinity membrane. By analyzing the adsorption mechanism, we reason that the energy of adsorption sites can be enhanced by electrical stimulation. We expect that a wide range of systems could be considered applying this strategy to improve adsorption property.

Evaluation of allelopathic effect of fifty Sorghum bicolor L. Genotypes on Germination and Growth of some weed in vitro and in vivo

The effect of root exudates of fifty Sorghum genotypes on seed germination and seedling growth of millet were studied in vitro. The fifty genotypes were divided into four groups according to their effect on percentage reduction in root and shoot and whole plant average lengths of millet seedling growth. The first group caused slight stimulation, the second slight inhibition, the third gave limited inhibition and the fourth caused high inhibition. In seedling growth. Five genotypes of sorghum were selected, one from group two and four from group four. These five genotypes were cultured in the field in Autumn 2007 and at the end of the season plants were removed, dried and grind. Three concentrations of each of these genotypes powder were prepared, in addition to the control treatment, (0.0, 3.0, 6.0 and 9.0) g/kg soil to study their effects on the growth of Amaranthus retroflexus which cultured in pots and kept in experimental field. Data on number of leaves, lengths of shoot and root and whole plant were taken as well as wet and dry weight were measured. Percentage of Amaranthus retroflexus seeds germination were evaluated in an experiment cultured in Petri dishes containing concentrations (0.0, 5.0 and 10.0%) of aqueous extracts of each of the five genotypes powder. Results showed high significant inhibition for the four genotypes from group four in comparison with the one genotype from group two. Significant differences among these genotypes in their inhibition on such parameters as shoot, root, whole plant growth, number of leaves, and wet and dry weight. The genotype 2005-K-Type 1050 gave the highest reduction in plant length 53.2% incomparing with the genotype 2005-K-Type 1033 which gave 0.7%. The percentage of seed germination of Amaranthus retroflexus was significantly reduced as the concentration of the aqueous extract increased and there were significant differences among genotypes on this parameter. The concentration of the powder of each genotype added to the soil produced significant reduction in all parameters studied and the effect increased as the concentration increased in soil. This research discusses the potential of the allelopathic effect of some Sorghum genotypes on weed germination and growth reduction and the possibility of employing them in weed control program with the intention to use less herbicide.

Construction of an amperometric triglyceride biosensor using PVA membrane bound enzymes

Objectives A method is described for construction of an amperometric triglyceride (TG) biosensor using PVA membrane bound enzymes. Design and methods A mixture of commercial lipase, glycerol kinase, glycerol-3-phosphate oxidase and horseradish peroxidase was co-immobilized onto polyvinyl alcohol (PVA) membrane through glutaraldehyde coupling. The biosensor measures current when polarized at 0.4 V. Results The sensor showed optimum response within 2 s at pH 7.0 and 25 °C. The current (mA) was in proportion to concentration of TG in the range 0.56–2.25 mM. The minimum detection limit of the method was 0.21 mM. The analytic recovery of added TG was 94.3%. Within batch and between batch coefficients of variations (CV) were < 5.85% and < 4.13%, respectively. A good correlation ( r = 0.99) was found. Among various serum substances tested, only cholesterol caused slight stimulation (20%). Conclusions An amperometric method was developed for determination of TG employing this enzyme electrode.