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11.
Influence of Cannabinoids on Electrically Evoked Dopamine Release and Cyclic AMP Generation in the Rat Striatum 总被引:6,自引:2,他引:4
Anna-Karina Cadogan Stephen P. H. Alexander E. Andrew Boyd David A. Kendall 《Journal of neurochemistry》1997,69(3):1131-1137
Abstract: Using the endogenous cannabinoid receptor agonist anandamide, the synthetic agonist CP 55940 {[1α,2β( R )5α]-(−)-5-(1,1-dimethylheptyl)-2-[5-hydroxy-2-(3-hydroxypropyl)cyclohexyl]phenol}, and the specific antagonist SR 141716 [ N -(piperidin-1-yl)-5-(4-chlorophenyl)-1-(2,4-dichlorophenyl)-4-methyl-1 H -pyrazole-3-carboxamide hydrochloride], second messenger activation of the central cannabinoid receptor (CB1) was examined in rat striatal and cortical slices. The effects of these cannabinoid ligands on electrically evoked dopamine (DA) release from [3 H]dopamine-prelabelled striatal slices were also investigated. CP 55940 (1 µ M ) and anandamide (10 µ M ) caused significant reductions in forskolin-stimulated cyclic AMP accumulation in rat striatal slices, which were reversed in the presence of SR 141716 (1 µ M ). CP 55940 (1 µ M ) had no effect on either KCl- or neurotransmitter-stimulated 3 H-inositol phosphate accumulation in rat cortical slices. CP 55940 and anandamide caused significant reductions in the release of dopamine after electrical stimulation of [3 H]dopamine-prelabelled striatal slices, which were antagonised by SR 141716. SR 141716 alone had no effect on electrically evoked dopamine release from rat striatal slices. These data indicate that the CB1 receptors in rat striatum are negatively linked to adenylyl cyclase and dopamine release. That the CB1 receptor may influence dopamine release in the striatum suggests that cannabinoids play a modulatory role in dopaminergic neuronal pathways. 相似文献
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The peroxidase activities in leaves from resistant and susceptible cultivars of wheat infected and non-infected by Erysiphe graminis DC were studied. In non-infected wheat, soluble and ionic bound peroxidase activity level was found to be higher in the resistant cultivar than that in the one susceptible to Erysiphe graminis DC. After infecting wheat leaves with Erysiphe graminis DC a remarkable increase in the activity of soluble and ionic bound peroxidases was detected 5 days after inoculation only in the resistant cultivar. In the susceptible cultivar a high increase in the activity of the soluble and ionic bound peroxidases occurred only 15 days after inoculation. Using ion exchange chromatography four peroxidase fractions were obtained from infected susceptible and resistant cultivars as from non-infected ones. The fraction II in non-inoculated resistant cultivars was much higher than that in the susceptible one. This fraction increased after inoculation in both cases reaching a higher level in resistant cultivars. Fraction I was higher in the susceptible cultivar. Electrofocusing profiles of peroxidase from the susceptible and resistant cultivar differed from one another. New peroxidase bands after inoculation appeared only in the resistant cultivar. 相似文献
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Magdalena Plotka Anna-Karina Kaczorowska Aleksandra Stefanska Agnieszka Morzywolek Olafur H. Fridjonsson Stanislaw Dunin-Horkawicz Lukasz Kozlowski Gudmundur O. Hreggvidsson Jakob K. Kristjansson Slawomir Dabrowski Janusz M. Bujnicki Tadeusz Kaczorowski 《Applied and environmental microbiology》2014,80(3):886-895
In this study, we present the discovery and characterization of a highly thermostable endolysin from bacteriophage Ph2119 infecting Thermus strain MAT2119 isolated from geothermal areas in Iceland. Nucleotide sequence analysis of the 16S rRNA gene affiliated the strain with the species Thermus scotoductus. Bioinformatics analysis has allowed identification in the genome of phage 2119 of an open reading frame (468 bp in length) coding for a 155-amino-acid basic protein with an Mr of 17,555. Ph2119 endolysin does not resemble any known thermophilic phage lytic enzymes. Instead, it has conserved amino acid residues (His30, Tyr58, His132, and Cys140) that form a Zn2+ binding site characteristic of T3 and T7 lysozymes, as well as eukaryotic peptidoglycan recognition proteins, which directly bind to, but also may destroy, bacterial peptidoglycan. The purified enzyme shows high lytic activity toward thermophiles, i.e., T. scotoductus (100%), Thermus thermophilus (100%), and Thermus flavus (99%), and also, to a lesser extent, toward mesophilic Gram-negative bacteria, i.e., Escherichia coli (34%), Serratia marcescens (28%), Pseudomonas fluorescens (13%), and Salmonella enterica serovar Panama (10%). The enzyme has shown no activity against a number of Gram-positive bacteria analyzed, with the exception of Deinococcus radiodurans (25%) and Bacillus cereus (15%). Ph2119 endolysin was found to be highly thermostable: it retains approximately 87% of its lytic activity after 6 h of incubation at 95°C. The optimum temperature range for the enzyme activity is 50°C to 78°C. The enzyme exhibits lytic activity in the pH range of 6 to 10 (maximum at pH 7.5 to 8.0) and is also active in the presence of up to 500 mM NaCl. 相似文献
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The majority of Gram-negative bacteria transfer O antigen polysaccharides onto the lipid A-core oligosaccharide via the action of surface polymer:lipid A-core ligases (WaaL). Here, we characterize the WaaL proteins of Vibrio cholerae with emphasis on structural and functional characterization of O antigen transfer and core oligosaccharide recognition. We demonstrate that the activity of two distantly related O antigen ligases is dependent on the presence of N-acetylglucosamine, and substitution of an additional sugar, i.e. galactose, alters the site specificity of the core oligosaccharide necessitating discriminative WaaL types. Protein topology analysis and a conserved domain search identified two distinct conserved motifs in the periplasmic domains of WaaL proteins. Site-directed mutagenesis of the two motifs, shown for WaaLs of V. cholerae and Salmonella enterica, caused a loss of O antigen transfer activity. Moreover, analogy of topology and motifs between WaaLs and O polysaccharide polymerases (Wzy) reveals a relationship between the two protein families, suggesting that the catalyzed reactions are related to each other. 相似文献