Sesquiterpene lactones as chemotaxonomic markers in genus Anthemis

Sesquiterpene lactones isolated from the genus Anthemis are used as chemotaxonomic markers. The obtained results support with some exceptions the botanical classification in Flora Europaea. Discrepancy between the lactone profile, cluster analysis and classification of A. melampodina, A. macedonica and A. austriaca in the genus Anthemis is discussed. The lactone composition of the undescribed as an European species A. plutonia correlates well with the guaianolide containing group of sect. Hiorthia.     

Effect of Plant Type on the Persistence of Beauveria bassiana

Field evaluation of isolate MK 2001 of the entomopathogenic fungus Beauveria bassiana (Balsamo) Vuillemin, revealed conidia persistence and infectivity up to 26 days on foliage of lettuce and celery, two crops with substantial plant differences. Plants were treated at a rate of 100 ml/cage at a concentration of 1×10⁸ conidia/ml. The number of colony-forming units (CFU) recovered immediately after treatments from discs sampled on lettuce and celery leaves were not significantly different, due to similar foliar coverage of conidia by application. Significant differences were observed between both host plants during the 26 days of the field trial. The number of CFUs recovered on lettuce was significantly higher than that on celery leaves. However, for each host plant, there were no significant differences either between lettuce external leaves and internal leaves or between celery canopy and bottom leaves. An in vitro pathogenicity test carried out on Lygus lineolaris adults fed with leaf discs harvested from treated cages resulted in a high pathogenicity of B. bassiana isolate MK 2001. The mortality immediately after treatment did not differ from the death counts taken every other day for 26 days. However, efficacy was significantly different between both plants. Mortality was 91% on lettuce and 78% on celery, 7 days post-treatment. This study highlighted that plant type must be taken into account in foliar application of B. bassiana.     

The effect of thermal treatment on antibacterial properties of nanostructured TiO<Subscript>2</Subscript>(N) films illuminated with visible light

This work focuses on the photocatalytic performances and antibacterial activity of nitrogen doped TiO₂ nanosystems with three and five layers obtained by a sol-gel route, followed by thermal treatment in oxygen or ammonia atmosphere at temperatures between 400 and 1000°C. Subsequently, the antibacterial activity of the obtained nanosystems on the Escherichia coli cells are determined and discussed. The obtained results show a significant dependence of the functional performances on the system’s composition. In particular, the antimicrobial activity of nitrogen-doped TiO₂ films is correlated with the temperature of thermal treatment and illumination time with visible artificial light.     

Design and synthesis of new stabilized combi-triazenes for targeting solid tumors expressing the epidermal growth factor receptor (EGFR) or its closest homologue HER2

The monoalkyltriazene moiety lends itself well to the design of combi-molecules. However, due to its instability under physiological conditions, efforts were directed towards stabilizing it by grafting a hydrolysable carbamate onto the 3-position. The synthesis and biological activities of these novel N-carbamyl triazenes are described.     

Amperometric acetylthiocholine sensor based on acetylcholinesterase immobilized on nanostructured polymer membrane containing gold nanoparticles

Poly(acrylonitrile-methylmethacrylate-sodium vinylsulfonate) membranes were chemically modified and loaded with gold nanoparticles. Acetylcholinesterase was immobilized on the prepared membranes in accordance with two distinctive procedures, the first of which involved immobilization of the enzyme by convection, and the other by diffusion. The prepared enzyme carriers were used for the construction of amperometric biosensors for detection of acetylthiocholine.Two sets of experiments were carried out. The first set was designed so that to evaluate the effects of the gold nanoparticle deployment and the immobilization procedures over the biosensor effectiveness. The other set of experiments was conducted in order to determine the influence of the individual components of the enzyme mixture, containing gold nanoparticles, acetylcholinesterase, bovine serum albumin and glutaraldehyde, over the current output of the constructed acetylthiocholine biosensors. The optimum composition of the mixture was determined to be as follows: enzyme, 0.1 U ml^?1; gold nanoparticles, 0.50 ml (per 1 ml enzyme mixture); albumin, 0.5% and glutaraldehyde, 0.7%.On the basis of the experimental results, the most efficient enzyme membrane was selected and used for the preparation of an acetylthiocholine biosensor. Its basic amperometric characteristics were investigated. A calibration plot was obtained for ATCh concentration ranging from 10 to 400 μM. A linear interval was detected along the calibration curve from 10 to 170 μM. The sensitivity of the constructed biosensor was calculated to be 0.066 μA μM^?1 cm^?2. The correlation coefficient for this concentration range was 0.996. The detection limit with regard to ATCh was calculated to be 1.80 μM.The potential application of the biosensor for detection and quantification of organophosphate pesticides was investigated as well. It was tested against sample solutions of Paraoxon. The biosensor detection limit for Paraoxon was determined, 7.39 × 10^?11 g l^?1, as well as the concentration interval (10^?10 to 10^?7 g l^?1) within which the biosensor response was linearly dependant on Paraoxon concentration.Finally the storage stability of the enzyme carrier was traced for a period of 50 days. After storage for 20 days the sensor retained 75% of its initial current response and after 30 days ?25%.     

Effects of voltage-gated calcium channel subunit genes on calcium influx in cultured C. elegans mechanosensory neurons

Voltage-gated calcium channels (VGCCs) serve as a critical link between electrical signaling and diverse cellular processes in neurons. We have exploited recent advances in genetically encoded calcium sensors and in culture techniques to investigate how the VGCC alpha1 subunit EGL-19 and alpha2/delta subunit UNC-36 affect the functional properties of C. elegans mechanosensory neurons. Using the protein-based optical indicator cameleon, we recorded calcium transients from cultured mechanosensory neurons in response to transient depolarization. We observed that in these cultured cells, calcium transients induced by extracellular potassium were significantly reduced by a reduction-of-function mutation in egl-19 and significantly reduced by L-type calcium channel inhibitors; thus, a main source of touch neuron calcium transients appeared to be influx of extracellular calcium through L-type channels. Transients did not depend directly on intracellular calcium stores, although a store-independent 2-APB and gadolinium-sensitive calcium flux was detected. The transients were also significantly reduced by mutations in unc-36, which encodes the main neuronal alpha2/delta subunit in C. elegans. Interestingly, while egl-19 mutations resulted in similar reductions in calcium influx at all stimulus strengths, unc-36 mutations preferentially affected responses to smaller depolarizations. These experiments suggest a central role for EGL-19 and UNC-36 in excitability and functional activity of the mechanosensory neurons.     

Physiological implications of adenosine receptor‐mediated platelet aggregation

Adenosine is an important mediator of inhibition of platelet activation. This metabolite is released from various cells, as well as generated via activity of ecto‐enzymes on the cell surface. Binding of adenosine to A₂ subtypes (A_2A or A_2B), G‐protein coupled adenosine receptors, results in increased levels of intracellular cyclic adenosine monophosphate (cAMP), a strong inhibitor of platelet activation. The role and importance of adenosine and its receptors in platelet physiology are addressed in this review, including recently identified roles for the A_2B adenosine receptor as a modulator of platelet activation through its newly described role in the control of expression of adenosine diphosphate (ADP) receptors. J. Cell. Physiol. 226: 46–51, 2010. © 2010 Wiley‐Liss, Inc.