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  • 1
    Electronic Resource
    Electronic Resource
    Immunohistochemical Localization of Five Members of the KV1 Channel Subunits: Contrasting Subcellular Locations and Neuron-specific Co-localizations in Rat Brain (1995)
    Oxford, UK : Blackwell Publishing Ltd
    European journal of neuroscience 7 (1995), S. 0 
    Details
    ISSN: 1460-9568
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: A large variety of potassium channels is involved in regulating integration and transmission of electrical signals in the nervous system. Different types of neurons, therefore, require specific patterns of potassium channel subunit expression and specific regulation of subunit coassembly into heteromultimeric channels, as well as subunit-specific sorting and segregation. This was investigated by studying in detail the expression of six different α-subunits of voltage-gated potassium channels in the rat hippocampus, cerebellum, olfactory bulb and spinal cord, combining in situ hybridization and immunocytochemistry. Specific polyclonal antibodies were prepared for five α-subunits (KV1.1, KV1.2, KV1.3, KV1.4, KV1.6) of the Shaker-related subfamily of rat Kv channels, which encode delayed-rectifier type and rapidly inactivating A-type potassium channels. Their distribution was compared to that of an A-type potassium channel (KV3.4), belonging to the Shaw-related subfamily of rat Kv channels. Our results show that these Kv channel α-subunits are differentially expressed in rat brain neurons. We did not observe in various neurons a stereotypical distribution of Kv channel α-subunits to dendritic and axonal compartments, but a complex differential subcellular subunit distribution. The different Kv channel subunits are targeted either to presynaptic or to postsynaptic domains, depending on neuronal cell type. Thus, distinct combinations of Kv1 α-subunits are co-localized in different neurons. The implications of these findings are that both differential expression and assembly as well as subcellular targeting of Kv channel α-subunits may contribute to Kv channel diversity and thereby to presynaptic and postsynaptic membrane excitability.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1460-9568.1995.tb00641.x
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  • 2
    Electronic Resource
    Electronic Resource
    Dopamine depresses cholinergic oscillatory network activity in rat hippocampus (2003)
    Oxford, UK : Blackwell Science, Ltd
    European journal of neuroscience 18 (2003), S. 0 
    Details
    ISSN: 1460-9568
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: The dopaminergic neuronal system is implicated in cognitive processes in a variety of brain regions including the mesolimbic system. We have investigated whether dopamine also affects synchronized network activity in the hippocampus, which has been ascribed to play a pivotal role in memory formation. Gamma frequency (20–80 Hz) oscillations were induced by the cholinergic agonist carbachol. Oscillatory activity was examined in area CA3 of Wistar rat hippocampal slices, employing field potential and intracellular recordings. Application of carbachol initiated synchronized population activity in the gamma band at 40 Hz. Induced gamma activity persisted over hours and required GABAA receptors. Dopamine reversibly decreased the integrated gamma band power of the carbachol rhythm by 62%, while its frequency was not changed. By contrast, individual pyramidal cells recorded during carbachol-induced field gamma activity exhibited theta frequency (5–15 Hz) membrane potential oscillations that were not altered by dopamine. The dopamine effect on the field gamma activity was mimicked by the D1 receptor agonist SKF-383393 and partially antagonized by the D1 antagonist SCH-23390. Conversely, the D2 receptor agonist quinpirole failed to depress the oscillations, and the D2 antagonist sulpiride did not prevent the suppressive dopamine effect. The data indicate that dopamine strongly depresses cholinergic gamma oscillations in area CA3 of rat hippocampus by activation of D1-like dopamine receptors and that this effect is most likely mediated via impairment of interneurons involved in generation and maintenance of the carbachol-induced network rhythm.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1460-9568.2003.02970.x
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  • 3
    Electronic Resource
    Electronic Resource
    Haptenylation of antibodies during affinity purification: a novel and convenient procedure to obtain labeled antibodies for quantification and double labeling (1998)
    Springer
    Histochemistry and cell biology 110 (1998), S. 311-322 
    Details
    ISSN: 1432-119X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract  Haptenylation of primary antibodies is a useful technique for multiple purposes. It is a technically straightforward procedure, as many haptens are available as N-hydroxysuccinimide esters or isothiocyanates. Unfortunately, the hapten group may become covalently attached to or close to the combining site of antibodies, lectins, or other ligand-binding proteins during the process of haptenylation. Thus, the interaction of the corresponding protein with its ligand may become severely hampered. To overcome this restriction, we developed a novel procedure for the haptenylation of polyclonal antibodies that combines purification and haptenylation. Haptenylation during adsorption to the affinity matrix combines two advantages: the antigen binding site is protected and the labeling procedure becomes most convenient, as overlabeled proteins and unreacted haptens are easily removed by simple washing. Haptenylation during adsorption to the affinity matrix is a two-phase reaction, which requires different conditions to the conventional procedure. To obtain such optimal conditions, stabilities and reactivities of N-hydroxysuccinimide esters and isothiocyanate groups were investigated with a newly developed assay. Based on this information, antibodies against two recently described calcium-binding proteins, NCS-1 and NVP-3, were biotinylated or digoxigenylated. The haptenylated antibodies were successfully applied for biochemical determination and simultaneous immunoenzymatic double labeling of the two proteins.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004180050293
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  • 4
    Electronic Resource
    Electronic Resource
    Subcellular site of the biosynthesis ofO-acetylated sialic acids in bovine submandibular gland (1988)
    Springer
    Glycoconjugate journal 5 (1988), S. 257-270 
    Details
    ISSN: 1573-4986
    Keywords: O-acetylated sialic acids ; O-acetyltransferase. bovine submandibular gland subcellular site ; tissue fractionation ; Acetyl-CoA:N-acetylneuraminate-9(or 7)-O-acetyltransferase (EC 2.3.1.45) ; sialidase or acylneuraminate hydrolase (EC 3.2.1.18) ; sialyltransferase (EC 2.4.99.3) ; acid phosphatase (EC 3.1.3.2) ; alkaline phosphatase (EC 3.1.3.1) ; NADP-dependent isocitrate dehydrogenase (EC 1.1.1.42) ; 5′-nucleotidase (EC 3.1.3.5) ; Na+ ; K+-dependent adenosine triphosphatase (EC 3.6.1.3) ; β-galactosidase (EC 3.2.1.23)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Bovine submandibular glands were homogenized and fractionated under conditions which yielded subcellular fragments from mainly one cell type, the mucous acinar cell, as judged by morphological analysis of the glands before and after homogenization. The majorN-acetylneuraminate-9(7)-O-acetyltransferase activity was detected in the cytosolic fraction, a result supported by the high specific radioactivity of free sialic acids isolated after [14C]acetate-labelling experiments. Separation of membranes on a Ficoll density gradient gave six fractions which were analyzed biochemically and morphologically. The particulate activities of acetyltransferase and sialyltransferase were found in fractions containing smooth and mitochondrial membranes. MembraneO-acetyl sialic acids were present at the highest levels in these fractions and also had the highest specific radioactivity after [14C]acetate-labelling experiments. Significant amounts of theO-acetyltransferase activity also occur in the cytosol and are consistent with a model ofO-acetyl sialic acid biosynthesis involving both cytosolic and smooth membrane sites ofO-acetylation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01049086
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  • 5
    Electronic Resource
    Electronic Resource
    Characterization of the major and minor mucus glycoproteins from bovine submandibular gland (1991)
    Springer
    Glycoconjugate journal 8 (1991), S. 330-339 
    Details
    ISSN: 1573-4986
    Keywords: mucin ; sialic acids ; submandibular gland ; glycoproteins ; oligosaccharides ; sialidases
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Two mucins were isolated from bovine submandibular glands and termed major and minor on a quantitative basis. The major mucin representing over 80% of the total glycoprotein fraction contained 37% of its dry weight as protein in contrast to 62% for the minor mucin. Differences in the amino acid composition reflected the higher proportion of typically non-glycosylated peptide in the minor mucin. The molar ratio ofN-acetylgalactosamine to serine plus threonine was 0.82 in major and 0.65 in minor mucins, indicating a lower degree of substitution of potential glycosylation sites in the minor mucin. Differences in the carbohydrate composition were found largely related to the sialic acids, with higher relative amounts ofN-glycoloylneuraminic acid in the minor mucin. In addition, the proportion of di-O-acetylated sialic acids was higher in the major mucin. The rate of sialidase action on the two mucins could be correlated with the content ofN-glycoloylneuraminic acid in each glycoprotein. There was no difference in the type of oligosaccharide found in each mucin and the differences in relative proportions reflected the monosaccharide composition for the two mucins. Gel filtration on Sepharose CL 2B showed a lower molecular weight distribution for the minor in contrast to the major mucin which was partially excluded. Density gradient centrifugation reflected this variation. SDS-PAGE demonstrated a regular banding pattern for the major mucin with a lowest subunit size of 1.8×105 Da and aggregates in excess of 106 Da, while the minor mucin ranged from 3.0 × 105 to 106 Da. The chemical composition of the isolated mucins was compared with previous histochemical analysis of mucin distribution in bovine submandibular glands and indicates a possible cellular location for each mucin.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00731345
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