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  • 1
    Electronic Resource
    Electronic Resource
    Pupillary dilation response as an indicator of auditory discrimination in the barn owl (2000)
    Springer
    Journal of comparative physiology 186 (2000), S. 425-434 
    Details
    ISSN: 1432-1351
    Keywords: Key words Habituation ; Frequency discrimination ; Minimum audible angle ; Sound localization ; Psychoacoustics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The pupil of an awake, untrained, head-restrained barn owl was found to dilate in response to sounds with a latency of about 25 ms. The magnitude of the dilation scaled with signal-to-noise ratio. The dilation response habituated when a sound was repeated, but recovered when stimulus frequency or location was changed. The magnitude of the recovered response was related to the degree to which habituating and novel stimuli differed and was therefore exploited to measure frequency and spatial discrimination. Frequency discrimination was examined by habituating the response to a reference tone at 3 kHz or 6 kHz and determining the minimum change in frequency required to induce recovery. We observed frequency discrimination of 125 Hz at 3 kHz and 250 Hz at 6 kHz – values comparable to those reported by others using an operant task. Spatial discrimination was assessed by habituating the response to a stimulus from one location and determining the minimum horizontal speaker separation required for recovery. This yielded the first measure of the minimum audible angle in the barn owl: 3° for broadband noise and 4.5° for narrowband noise. The acoustically evoked pupillary dilation is thus a promising indicator of auditory discrimination requiring neither training nor aversive stimuli.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003590050442
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  • 2
    Electronic Resource
    Electronic Resource
    Cloning and expression of the chicken immunoglobulin joining (J)-chain cDNA (2000)
    Springer
    Immunogenetics 51 (2000), S. 85-91 
    Details
    ISSN: 1432-1211
    Keywords: Key words J chain ; Polymeric immunoglobulin ; Ontogeny ; Evolution ; Comparative immunology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract  The J chain is a component of polymeric immunoglobulin (Ig) molecules and may play an important role in their polymerization and the transport of polymeric Ig across epithelial cells. In this study, the primary structure of the chicken J chain was determined by sequencing cDNA clones. The cDNA had an open reading frame of 476 nucleotides encoding a putative protein of 158 amino acid residues including the signal sequence. The 3′ untranslated region consisted of 1216 nucleotides and a poly(A) tail. The deduced amino acid sequence of the chicken J chain had a high degree of homology to that of human, cow, rabbit, mouse, frog, and earthworm, with eight conserved Cys residues identical to the mammalian J chains. Northern blot hybridization performed with total RNA from various chicken tissues revealed high levels of J-chain mRNA expression in spleen, intestine, Harderian gland, and bursa of Fabricius, and low levels in the thymus. The J chain was expressed in the bursa as early as day 15 of embryogenesis. These data indicated that the chicken J-chain gene displays a high degree of homology with that of other species, and is expressed at an early stage of development of the chicken immune system.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002510050016
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Role of nuclear factor-κ B in the expression by tumor necrosis factor-α of the human polymeric immunoglobulin receptor (pIgR ) gene (2000)
    Springer
    Immunogenetics 51 (2000), S. 289-295 
    Details
    ISSN: 1432-1211
    Keywords: Key words Human ; Mucosa ; Gene regulation ; Cytokines ; Transcription factors
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract  We analyzed the mechanism of human polymeric immunoglobulin receptor (pIgR) gene upregulation by tumor necrosis factor (TNF)-α. Northern blot analysis showed that the expression of pIgR mRNA was enhanced by TNF-α stimulation. This activation was completely inhibited by RNA polymerase or protein synthesis inhibitors, suggesting that the regulation of pIgR gene expression depends on de novo RNA and protein synthesis. Furthermore, the stimulation of pIgR mRNA by TNF-α was decreased by pyrrolidinedithiocarbamate and l-1-4′-tosylamino-phenylethyl-chloromethyl ketone, which are known nuclear factor (NF)-κB inhibitors. For further analysis of gene regulation, we cloned and sequenced the 1.5-kb 5′-flanking region of the pIgR gene. In the upstream region, we found two NF-κB-binding motifs (named κB1 and κB2 from the 5′ region). An electrophoretic mobility shift assay indicated that two components of the NF-κB/Rel family, p50 and p65, bound with higher affinity to the κB2 element than to the κB1 element. We also analyzed pIgR gene expression using reporter plasmids expressing the firefly luciferase gene. Stimulation by TNF-α significantly activated the pIgR gene promoter, as a 775-bp upstream region of the pIgR gene increased luciferase gene expression in cells treated with TNF-α. The activation of promoter activity by TNF-α was abolished when a mutation was inserted into κB1 or κB2. These data indicated that pIgR gene expression induced by TNF-α is transcriptionally regulated via activation of NF-κB. In addition, there is a possibility that another factor may act in concert with NF-κB.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002510050622
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    Paper (German National Licenses)
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