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  • 1
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 28 (1993), S. 1542-1546 
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Peptide profiles of single neurons in Lymnaea stagnalis were directly characterized by matrix-assisted laser desorption-ionization mass spectrometry. The mass analysis was performed after minor pretreatment and without any separation steps. Good-quality spectra were obtained of several cell types and also other tissues. The results were compared with the results of conventional peptide chemical methods. In addition to many known peptides, several new peptides were identified. The method provides new opportunities for studying peptide compositions at the single-cell level, which is shown to have many advantages.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Science Ltd
    Journal of neurochemistry 89 (2004), S. 0 
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: The activity-dependent release of peptides from the neuro-endocrine caudodorsal cell (CDC) system of the freshwater snail Lymnaea stagnalis regulates egg laying and related behaviors. In this study, we optimized a mass spectrometry-based approach to study the spatio-temporal dynamics of peptides that are largely derived from the CDC hormone precursor during an egg-laying cycle and a CDC discharge in vitro. Semi-quantitative peptide mass profiling using matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) indicated a massive depletion of peptides from the neurohemal area in the cerebral commissure (COM) during egg laying and the existence of a reserve pool of peptides in the CDC somata that were transported to the COM to restore peptide levels. The depletion of CDC peptides from the COM was correlated to their release during an induced electrical discharge in vitro. Moreover, MALDI-MS of the releasate revealed extensive truncation of the carboxyl terminal peptide. Finally, two novel peptides of 1788 and 5895 Da, not encoded by the CDC hormone precursor, also exhibited temporal quantitative changes similar to those of CDC peptides. Sequencing of the peptide of 1788 Da by tandem mass spectrometry yielded the novel sequence HF(FH)FYGPYDVFQRDVamide. Together, this implicates a more complex set of CDC peptides for the regulation of egg laying than previously anticipated.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Science Ltd
    Journal of neurochemistry 81 (2002), S. 0 
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: A proteomics approach was used to identify the translation products of a unique synaptic model system, squid optic lobe synaptosomes. Unlike its vertebrate counterparts, this preparation is largely free of perikaryal cell fragments and consists predominantly of pre-synaptic terminals derived from retinal photoreceptor neurones. We metabolically labelled synaptosomes with [35S]methionine and applied two-dimensional gel electrophoresis to resolve newly synthesized proteins at high resolution. Autoradiographs of blotted two-dimensional gels revealed de novo synthesis of about 80 different proteins, 18 of which could be matched to silver-stained gels that were run in parallel. In-gel digestion of the matched spots and mass spectrometric analyses revealed the identities of various cytosolic enzymes, cytoskeletal proteins, molecular chaperones and nuclear-encoded mitochondrial proteins. A number of novel proteins (i.e. not matching with database sequences) were also detected. In situ hybridization was employed to confirm the presence of mRNA and rRNA in synaptosomes. Together, our data show that pre-synaptic endings of squid photoreceptor neurones actively synthesize a wide variety of proteins involved in synaptic functioning, such as transmitter recycling, energy supply and synaptic architecture.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Science Ltd
    Journal of neurochemistry 87 (2003), S. 0 
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: In the simultaneous hermaphrodite snail Lymnaea stagnalis, copulation as a male is controlled by neurons that send axons to the male copulatory organs via a single penis nerve. Using direct mass spectrometry of a penis nerve sample, we show that one of the molecular ions has a mass corresponding to GAPRFVamide, previously identified from the buccal ganglia, and named Lymnaea inhibitory peptide (LIP). The identity of this peptide is confirmed by partial peptide purification from the penis nerve, followed by post source decay mass spectrometry. We cloned the LIP-encoding cDNA, which predicts a prohormone that gives rise to five copies of LIP (now re-named LIP A), two other –FVamide peptides (LIPs B and C), and five structurally unrelated peptides. The LIP gene is expressed in neurons of the right cerebral ventral lobe that send their axons into the penis nerve. We show that the LIP A peptide is present in these neurons and in the penis nerve, and confirmed the presence of LIP B and C in the penis nerve by post source decay mass spectrometry. Finally, we demonstrate that LIP A, B and C inhibit the contractions of the penis retractor muscle, thereby implicating their role in male copulation behavior.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 62 (1994), S. 0 
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: Neuropeptides were directly detected in single identified neurons and the neurohemal area of peptidergic (neuroendocrine) systems in the Lymnaea brain by using matrix-assisted laser desorption ionization mass spectrometry (MALDI-MS). The samples were placed in matrix solution and ruptured to allow mixing of cell contents with the matrix solution. After formation of matrix crystals, the analytes were analyzed by MALDI-MS. It was surprising that clean mass spectra were produced, displaying extreme sensitivity of detection. In one of the neuroendocrine systems studied, we could demonstrate for the first time, by comparing the peptide patterns of soma and of neurohemal axon terminals, that processing of the complex prohormone expressed in this system occurs entirely in the soma. In the other system studied, novel peptides could be detected in addition to peptides previously identified by conventional molecular biological and peptide chemical methods. Thus, complex peptide processing and expression patterns could be predicted that were not detected in earlier studies using conventional methods. As the first MALDI- MS study of direct peptide fingerprinting in the single neuron these experients demonstrate that MALDI-MS forms a new and valuable approach to the study of the synthesis and expression of bioactive peptides, with potential application to single-cell studies in vertebrates, including humans.
    Type of Medium: Electronic Resource
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