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  • 1
    Electronic Resource
    Electronic Resource
    Modelling spatiotemporal properties of directionally sensitive multi-input single-output systems (1993)
    Springer
    Biological cybernetics 69 (1993), S. 407-414 
    Details
    ISSN: 1432-0770
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Computer Science , Physics
    Notes: Abstract The dynamics of directionally tuned linear multi-input single-output systems varies generally as a function of the spatial orientation of the inputs. A linear system receiving directionally specific inputs is represented by a linear combination of the respective input transfer functions. The input-output behaviour of such systems can be described by a vector transfer function which specifies the polarization directions of the system in real space. These directions, which can be either one (unidirectional vector transfer function) or two (bidirectional vector transfer function) but never three, are obtained by computing the eigenvectors and eigenvalues of the system matrix that is defined by the gain and phase values of the system's response to harmonic stimulation directed along three orthogonal directions in space. The spatial tuning behaviour is determined by the quadratic form associated with the system matrix. Neuronal systems with bidirectional vector transfer functions process input information in a plane-specific way and exhibit novel characteristics, very much different from those of systems with unidirectional vector transfer functions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00199440
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  • 2
    Electronic Resource
    Electronic Resource
    Modelling spatiotemporal properties of directionally sensitive multi-input single-output systems (1993)
    Springer
    Biological cybernetics 69 (1993), S. 407-414 
    Details
    ISSN: 1432-0770
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Computer Science , Physics
    Notes: Abstract The dynamics of directionally tuned linear multi-input single-output systems varies generally as a function of the spatial orientation of the inputs. A linear system receiving directionally specific inputs is represented by a linear combination of the respective input transfer functions. The input-output behaviour of such systems can be described by a vector transfer function which specifies the polarization directions of the system in real space. These directions, which can be either one (unidirectional vector transfer function) or two (bidirectional vector transfer function) but never three, are obtained by computing the eigenvectors and eigenvalues of the system matrix that is defined by the gain and phase values of the system's response to harmonic stimulation directed along three orthogonal directions in space. The spatial tuning behaviour is determined by the quadratic form associated with the system matrix. Neuronal systems with bidirectional vector transfer functions process input information in a plane-specific way and exhibit novel characteristics, very much different from those of systems with unidirectional vector transfer functions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01185412
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  • 3
    Electronic Resource
    Electronic Resource
    Amplification of three threonine biosynthesis genes inCorynebacterium glutamicum and its influence on carbon flux in different strains (1991)
    Springer
    Applied microbiology and biotechnology 34 (1991), S. 617-622 
    Details
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary The hom-thrB operon (homoserine dehydrogenase/homoserine kinase) and the thrC gene (threonine synthase) of Corynebacterium glutamicum ATCC 13 032 and the hom FBR (homoserine dehydrogenase resistant to feedback inhibition by threonine) alone as well as hom FBR-thrB operon of C. glutamicum DM 368-3 were cloned separately and in combination in the Escherichia coli/C. glutamicum shuttle vector pEK0 and introduced into different corynebacterial strains. All recombinant strains showed 8- to 20-fold higher specific activities of homoserine dehydrogenase, homoserine kinase, and/or threonine synthase compared to the respective host. In wild-type C. glutamicum, amplification of the threonine genes did not result in secretion of threonine. In the lysine producer C. glutamicum DG 52-5 and in the lysine-plus-threonine producer C. glutamicum DM 368-3 overexpression of hom-thrB resulted in a notable shift of carbon flux from lysine to threonine whereas cloning of hom FBR-thrB as well as of hom FBR in C. glutamicum DM 368-3 led to a complete shift towards threonine or towards threonine and its precursor homoserine, respectively. Overexpression of thrC alone or in combination with that of hom FBR and thrB had no effect on threonine or lysine formation in all recombinant strains tested.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00167910
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  • 4
    Electronic Resource
    Electronic Resource
    Molecular aspects of lysine, threonine, and isoleucine biosynthesis inCorynebacterium glutamicum (1993)
    Springer
    Antonie van Leeuwenhoek 64 (1993), S. 145-163 
    Details
    ISSN: 1572-9699
    Keywords: isolecucine biosynthesis ; lysine ; threonine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The Gram-positive bacteriumCorynebactericum glutamicum is used for the industrial production of amino acids, e.g. of L-glutamate and L-lysine. In the last ten years genetic engineering methods were developed forC. glutamicum and consequently, recombinant DNA technology was employed to study the biosynthetic pathways and to improve the amino acid productivity by manipulation of enzymatic, transport and regulatory functions of this bacterium. The present review summarizes the current knowledge on the synthesis and over-production of the aspartate derived amino acids L-lysine, L-threonine and L-isoleucine inC. glutamicum. A special feature ofC. glutamicum is its abilily to convert the lysine intermediate piperideine2,6-dicarboxylate to diaminopimelate by two different routes, i.e. by reactions involving succinylated intermediates or by the single reaction of diaminopimelate dehydrogenase. The flux distribution over the two pathways is regulated by the ammonium availability. The overall carbon flux from aspartate to lysine, however, is governed by feedback-control of the aspartate kinase and by the level of dihydrodipicolinate synthase. Consequently, expression oflysC FBR encoding a deregulated aspartate kinase and/or the overexpression ofdapA encoding dihydrodipicolinate synthase led to overproduction of lysine. As a further specific featureC. glutamicum possesses a specific lysine export carrier which shows high activity in lysine overproducing mutants. Threonine biosynthesis is in addition to control by the aspartate kinase tightly regulated at the level of homoserine dehydrogenase which is subject to feedback-inhibition and to repression.C. glutamicum strains possessing a deregulated aspartate kinase and a deregulated homoserine dehydrogenase produce lysine and threonine. Amplification of deregulated homoserine dehydrogenase in such strain led to an almost complete redirection of the carbon flux to threonine. For a further flux from threonine to isoleucine the allosteric control of threonine dehydratase and of the acetohydroxy acid synthase are important. The expression of the genes encoding the latter enzyme is additionally regulated at the transcriptional level. By addition of 2-oxobutyrate as precursor and by bypassing the expression control of the acetohydroxy acid synthase genes high isoleucine overproduction can be obtained.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00873024
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  • 5
    Electronic Resource
    Electronic Resource
    Book reviews (1982)
    Springer
    Transportation 11 (1982), S. 311-319 
    Details
    ISSN: 1572-9435
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00172656
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  • 6
    Electronic Resource
    Electronic Resource
    Anatomical mapping of choline acetyltransferase (ChAT)-like and glutamate decarboxylase (GAD)-like immunoreactivity in outer hair cell efferents in adult rats (1991)
    Springer
    Cell & tissue research 266 (1991), S. 89-95 
    Details
    ISSN: 1432-0878
    Keywords: Cochlear efferents ; Immuno-electron microscopy ; Choline acetyltransferase ; Glutamate decarboxylase ; Rat (Wistar)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The distribution of choline acetyltransferase (ChAT)-like and glutamate decarboxylase (GAD)-like immunoreactivity in the cochleae of 15 adult Wistar white rats was investigated using the peroxidase-antiperoxidase (PAP) technique. A monoclonal antibody to ChAT and a polyclonal antiserum to GAD were used. Immunoreaction was investigated quantitatively, in the electron microscope, on tangential sections of the tunnel of Corti and the rows of outer hair cells. ChAT-like and GAD-like immunoreactivity was found in all efferent nerve fibres in the tunnel of Corti and in all efferent synapses on the outer hair cells. A coexistence of ChAT and GAD in the efferent system to the outer hair cells of the rat is therefore assumed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00678715
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  • 7
    Electronic Resource
    Electronic Resource
    The phosphoenolpyruvate carboxylase gene of Corynebacterium glutamicum: Molecular cloning, nucleotide sequence, and expression (1989)
    Springer
    Molecular genetics and genomics 218 (1989), S. 330-339 
    Details
    ISSN: 1617-4623
    Keywords: Corynebacterium glutamicum ; Phosphoenolpyruvate carboxylase ; ppc gene
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The ppc gene of Corynebacterium glutamicum encoding phosphoenolpyruvate (PEP) carboxylase was isolated by complementation of a ppc mutant of Escherichia coli using a cosmid gene bank of chromosomal c. glutamicum DNA. By subsequent subcloning into the plasmid pUC8 and deletion analysis, the ppc gene could be located on a 3.3 kb SalI fragment. This fragment was able to complement the E. coli ppc mutant and conferred PEP carboxylase activity to the mutant. The complete nucleotide sequence of the ppc gene including 5′ and 3′ flanking regions has been determined and the primary structure of PEP carboxylase was deduced. The sequence predicts a 919 residue protein product (molecular weight of 103154) which shows 34% similarity with the respective E. coli enzyme.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00331286
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  • 8
    Electronic Resource
    Electronic Resource
    Occurrence and regional distribution of striated muscle fibers in the rat pineal gland (1978)
    Springer
    Cell & tissue research 190 (1978), S. 349-355 
    Details
    ISSN: 1432-0878
    Keywords: Pineal gland ; Striated musculature ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary In a total of 96 rat pineals studied 31 were found to contain striated muscle fibers or their precursors. The muscle fibers were most frequently present in the stalk region and more frequently found in the left than in the right hemisphere. Size measurements revealed that the lengths of pineal muscle cell nuclei differ only slightly from those of the sphincter muscle of the iris. However, the yellowish appearance of pineal muscle cell nuclei under darkfield investigation, a phenomenon observed in all muscular tissues of mesenchymal origin and connective tissue cells, may support the hypothesis that pineal musculature is of mesenchymal rather than ectodermal origin.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00218180
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  • 9
    Electronic Resource
    Electronic Resource
    Time-related changes in size of nuclei of pinealocytes in rats (1981)
    Springer
    Cell & tissue research 218 (1981), S. 427-438 
    Details
    ISSN: 1432-0878
    Keywords: Pineal gland (rat) ; Circadian rhythm ; Infradian rhythm ; Karyometry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary In a study of 96 adult male Sprague-Dawley rats, da-and time-related changes of the mean nuclear volume of pinealocytes were determined with the aim of testing the reproducibility of the karyometric findings described by Quay and Renzoni (1966). It is shown (i) that statistically significant differences exist between the central and peripheral mean volumes of pinealocyte nuclei/group of animals and time point (p〈0.001), (ii) that the day and time related differences are statistically different in both regions (p〈0.001), (iii) that in the center and periphery of the pineal body different diurnal patterns exist, and (iv) that the diurnal patterns are not parallel in the two regions. The question discussed is (i) whether or not probable superimposed infradian rhythms may account for the different diurnal patterns, and (ii) whether these patterns in the two regions indicate functional differences between the “cortex” and the “medulla” of the rat pineal body.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00210355
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  • 10
    Electronic Resource
    Electronic Resource
    Occurrence and regional distribution of calcareous concretions in the rat pineal gland (1978)
    Springer
    Cell & tissue research 195 (1978), S. 359-366 
    Details
    ISSN: 1432-0878
    Keywords: Calcareous concretions ; Pineal gland ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Serial sections of 90 Sprague-Dawley rat brains with the pineal in situ were scanned to determine the occurrence and regional distribution of calcareous concretions within the pineal gland and its surrounding leptomeningeal tissue. In 90 % of the cases examined concretions were found in varying number and appearance, predominantly lying in the dorsal region of the pineal gland and in the distal portion of the pineal stalk. Discussing the hypothesis advanced by Lukaszyk and Reiter (1975) that the origin of pineal concretions may be related to a neurosecretory process involving a pineal carrier protein, called neuroepiphysin, it is thought that, in view of the intra- and extra-pineal occurrence of concretions, processes other than secretion should be considered. Since in the pineal organ lymphatics are lacking it may well be that, due to a reduced drainage of tissue fluid, the coagulation of intercellular organic debris mingled with minerals increases with age.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00236732
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