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71.
72.
Meurs H Santing RE Remie R van der Mark TW Westerhof FJ Zuidhof AB Bos IS Zaagsma J 《Nature protocols》2006,1(2):840-847
To investigate mechanisms underlying allergen-induced asthmatic reactions, airway hyperresponsiveness and remodeling, we have developed a guinea pig model of acute and chronic asthma using unanesthetized, unrestrained animals. To measure airway function, ovalbumin (IgE)-sensitized animals are permanently instrumented with a balloon-catheter, which is implanted inside the pleural cavity and exposed at the neck of the animal. Via an external cannula, the balloon-catheter is connected to a pressure transducer, an amplifier, an A/D converter and a computer system, enabling on-line measurement of pleural pressure (P(pl))-closely correlating with airway resistance-for prolonged periods of time. Using aerosol inhalations, the method has been successfully applied to measure ovalbumin-induced early and late asthmatic reactions and airway hyperresponsiveness. Because airway function can be monitored repeatedly, intra-individual comparisons of airway responses (e.g., to study drug effects) are feasible. Moreover, this model is suitable to investigate chronic asthma and airway remodeling, which occurs after repeated allergen challenges. The protocol for establishing this model takes about 4 weeks. 相似文献
73.
Kreier F Buijs RM 《American journal of physiology. Regulatory, integrative and comparative physiology》2007,293(1):R548-9; author reply R550-2, discussion R553-4
74.
Regulated exocytosis: merging ideas on fusing membranes 总被引:2,自引:0,他引:2
Cellular trafficking pathways end with fusion reactions at the target. These reactions have been studied extensively for many decades, but recent studies have been particularly productive in providing new solutions to old problems, especially in some of the most complex fusion reactions, like synaptic vesicle secretion in neurons. Here, we discuss new studies that begin to merge ideas on three central questions: (A) are all releasable vesicles equally likely to undergo fusion, (B) do different fusion modes contribute to synaptic transmission, and (C) which molecular events are 'upstream' and which ones 'downstream' of SNARE complex assembly. 相似文献
75.
Interdependence of PKC-dependent and PKC-independent pathways for presynaptic plasticity 总被引:4,自引:0,他引:4
Diacylglycerol (DAG) is a prominent endogenous modulator of synaptic transmission. Recent studies proposed two apparently incompatible pathways, via protein kinase C (PKC) and via Munc13. Here we show how these two pathways converge. First, we confirm that DAG analogs indeed continue to potentiate transmission after PKC inhibition (the Munc13 pathway), but only in neurons that previously experienced DAG analogs, before PKC inhibition started. Second, we identify an essential PKC pathway by expressing a PKC-insensitive Munc18-1 mutant in munc18-1 null mutant neurons. This mutant supported basic transmission, but not DAG-induced potentiation and vesicle redistribution. Moreover, synaptic depression was increased, but not Ca2+-independent release evoked by hypertonic solutions. These data show that activation of both PKC-dependent and -independent pathways (via Munc13) are required for DAG-induced potentiation. Munc18-1 is an essential downstream target in the PKC pathway. This pathway is of general importance for presynaptic plasticity. 相似文献
76.
77.
Gudrun Ruud 《Development genes and evolution》1925,105(2):209-293
Ohne Zusammenfassung 相似文献
78.
79.
Jennewein S Schürmann M Wolberg M Hilker I Luiten R Wubbolts M Mink D 《Biotechnology journal》2006,1(5):537-548
Aldolases are emerging as powerful and cost efficient tools for the industrial synthesis of chiral molecules. They catalyze enantioselective carbon-carbon bond formations, generating up to two chiral centers under mild reaction conditions. Despite their versatility, narrow substrate ranges and enzyme inactivation under synthesis conditions represented major obstacles for large-scale applications of aldolases. In this study we applied directed evolution to optimize Escherichia coli 2-deoxy-D-ribose 5-phosphate aldolase (DERA) as biocatalyst for the industrial synthesis of (3R,5S)-6-chloro-2,4,6-trideoxyhexapyranoside. This versatile chiral precursor for vastatin drugs like Lipitor (atorvastatin) is synthesized by DERA in a tandem-aldol reaction from chloroacetaldehyde and two acetaldehyde equivalents. However, E. coli DERA shows low affinity to chloroacetaldehyde and is rapidly inactivated at aldehyde concentrations useful for biocatalysis. Using high-throughput screenings for chloroacetaldehyde resistance and for higher productivity, several improved variants have been identified. By combination of the most beneficial mutations we obtained a tenfold improved variant compared to wild-type DERA with regard to (3R,5S)-6-chloro-2,4,6-trideoxyhexapyranoside synthesis, under industrially relevant conditions. 相似文献
80.
Meussen BJ Weusthuis RA Sanders JP Graaff LH 《Applied microbiology and biotechnology》2012,93(3):1167-1174
Cyanophycin or cyanophycin granule peptide is a protein that results from non-ribosomal protein synthesis in microorganisms
such as cyanobacteria. The amino acids in cyanophycin can be used as a feedstock in the production of a wide range of chemicals
such as acrylonitrile, polyacrylic acid, 1,4-butanediamine, and urea. In this study, an auxotrophic mutant (Rhizopus oryzae M16) of the filamentous fungus R. oryzae 99-880 was selected to express cyanophycin synthetase encoding genes. These genes originated from Synechocystis sp. strain PCC6803, Anabaena sp. strain PCC7120, and a codon optimized version of latter gene. The genes were under control of the pyruvate decarboxylase
promoter and terminator elements of R. oryzae. Transformants were generated by the biolistic transformation method. In only two transformants both expressing the cyanophycin
synthetase encoding gene from Synechocystis sp. strain PCC6803 was a specific enzyme activity detected of 1.5 mU/mg protein. In one of these transformants was both water-soluble
and insoluble cyanophycin detected. The water-soluble fraction formed the major fraction and accounted for 0.5% of the dry
weight. The water-insoluble CGP was produced in trace amounts. The amino acid composition of the water-soluble form was determined
and constitutes of equimolar amounts of arginine and aspartic acid. 相似文献