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  • 1
    Electronic Resource
    Electronic Resource
    Cytophysiology of neurosecretory axon terminals in the brain of an annelid (Ophryotrocha puerilis, Polychaeta) (1991)
    Springer
    Cell & tissue research 264 (1991), S. 339-345 
    Details
    ISSN: 1432-0878
    Keywords: Neurosecretion ; Catecholamines ; HPLC ; Immunohistochemistry ; Glyoxylic acid fluorescence ; Ophryotrocha puerilis (Annelida)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary In the posterior part of the brain of the protandric polychaete Ophryotrocha puerilis neurosecretory cells form prominent axon terminals. The terminals are arranged in two complexes. The perikarya of these presumably monopolar neurons are scattered in the anterior part of the cerebral perikaryal layer. In females the terminals store large amounts of neurosecretory material. It has been suggested earlier that neurosecretions of the terminals may play a role during sex reversal from females to males. Application of histamine caused the release of neurosecretory material from the respective terminals in females. However, this discharge was not followed by sex reversal. Application of reserpine had no influence on the terminals. Neither by in vivo observation nor by ultrastructural analysis any effect of reserpine on the terminal complexes could be observed. In isolated terminals filled with neurosecretory material from females, catecholamines could not be detected by HPLC. Also, polyclonal antibodies against dopamine did not stain the terminal complexes. Furthermore, the complexes did not develop any fluorescence after glyoxylic acid treatment. Therefore, the present results contradict the hypothesis that the neurosecretory material of the respective axon terminals is catecholaminergic and that it is involved in sex differentiation. The function of the secretory neurons studied here remains unclear.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00313972
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  • 2
    Electronic Resource
    Electronic Resource
    The catecholaminergic system of an annelid (Ophryotrocha puerilis, Polychaeta) (1991)
    Springer
    Cell & tissue research 265 (1991), S. 175-184 
    Details
    ISSN: 1432-0878
    Keywords: Nervous system ; Nervous system, peripheral ; Catecholamines ; Immunohistochemistry ; Glyoxylic acid fluorescence ; Ophryotrocha puerilis (Annelida)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The complex catecholaminergic (CA) nervous system of the polychaete Ophryotrocha puerilis is documented using glyoxylic acid induced fluorescence (GIF) and immunohistochemistry. CA-neurons are found both in the central and peripheral nervous system. In the brain, about 50 CA-neurons are present in the perikaryal layer together with numerous CA fibres. Two pairs of CA perikarya are characteristic for each ganglion of the ventral nerve cord. CA-neurites in the ventral nerve cord are mainly arranged in 4 strands paralleling the longitudinal axis of the worm. Fluorescent neurons with receptive ciliary structures are present in body appendages (antennae, palps, urites, parapodial cirri), in the body-wall, and within the oesophageal wall. Furthermore, a subepidermal nerve net of free CA nerve endings has been found. After incubation of specimens with dopamine prior to the development of GIF more fluorescent perikarya could be observed; the fluorescence was also intensified. Pre-incubation with reserpine reduced the intensity of GIF. Results of high pressure liquid chromatography and immunostaining with a polyclonal antibody against a dopamine-glutaraldehyde-complex suggest that dopamine is the major CA transmitter. It is thought that dopaminergic neurons together with ciliary receptive structures act as mechano- and/or chemoreceptors.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00318152
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  • 3
    Electronic Resource
    Electronic Resource
    The state dependence of the interaction of metastable rare gas atoms Rg*(ms3 P 2,3 P 0) (Rg=Ne, Ar, Kr, Xe) with ground state sodium atoms (1990)
    Springer
    The European physical journal 16 (1990), S. 237-249 
    Details
    ISSN: 1434-6079
    Keywords: 31.20Pv ; 31.50.+w ; 31.70.−f ; 34.20.−b ; 34.50.Gb ; 35.20.Gs ; 82.40.Dm
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Using crossed beams of metastable rare gas atoms Rg*(ms3 P 2,3 P 0) (Rg=Ne, Ar, Kr, Xe) and ground state sodium atoms Na(3s 2 S 1/2), we have measured the energy spectra of electrons released in the respective Penning ionization processes at thermal collision energies. For Rg*(3 P 2)+Na(3s), the spectra are quite similar for the different rare gases, both in width and shape; they reflect attractive interactions in the entrance channel with well depthsD* e [meV] decreasing slowly from Rg=Ne to Xe as follows: 676(18); 602(23); 565(26); 555(30). For Rg*(3 P 0)+Na(3s), the spectra vary strongly with the rare gas, indicating a change in the character of the interaction from van der Waals type attraction (Ne) to chemical binding for Kr and Xe with well depthsD* e [meV] of: 51(19); 107(25); 432(30); 530(50). These findings are explained through model calculations of the respective potential curves, in which the exchange and the spin orbit interaction in the excited rare gas and the molecular interaction between the two valences-electrons in terms of suitably chosen singlet and triplet potentials are taken into account. These calculations also explain qualitatively the experimental finding that the ratiosq 2/q 0 of the ionization cross sections for Rg*(3 P 2)+Na and Rg*(3 P 0)+Na vary strongly with the rare gas from Ne to Xe as follows: 15.8(3.2); 2.6(4); 1.4(2); 1.6(4).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01437526
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  • 4
    Electronic Resource
    Electronic Resource
    Experimental and theoretical studies of the Bi-excited collision systems He*(23 S) + He*(23 S, 21 S) at thermal and subthermal kinetic energies (1991)
    Springer
    The European physical journal 21 (1991), S. 89-112 
    Details
    ISSN: 1434-6079
    Keywords: 31.20.Di ; 34.50.Gb ; 52.20.Hv
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We have carried out a comprehensive experimental and theoretical investigation of the autoionizing collision systems He*(23 S, 21 S) + He*(23 S). We present high resolution electron energy spectra, obtained with a single He* beam (average relative collision energy 〈E rel〉=1.6 meV) and with crossed He* beams (〈E rel〉〉 =61 meV). The spectra show substantial structure, and under single beam conditions fast oscillations due to the interference of incoming and outgoing heavy particle waves in the entrance channels are observed. Accurate ab initio potential curves for the seven lowest He*—He*(Σ) molecular states have been obtained from a Feshbach projection scheme, and width functions for He*(23 S) + He*(23 S) have been derived by Stieltjes imaging. Based on these ab initio data, detailed quantum mechanical calculations of the electron spectra have been carried out and provide a thorough understanding of the experimentally observed spectral features. Good overall agreement of the calculated spectra with the experimental data is observed. The close coincidence in the positions of the experimental and theoretical peaks, especially for He*(23 S) + He*(23 S), underlines the reliability of the ab initio potentials. In the He*(21 S) + He*(23 S) electron spectrum, the dominant peak is traced to be due to autoionization from the 23Σ+ g molecular state accessed via an avoided crossing. We also present a detailed discussion of the total ionization cross sections σtot and of the fraction σAI/σtot for associative ionization together with a critical comparison with previous work. The ionization probabilities for close collisions in entrance channels, from which autoionization is spin-allowed, are near unity, and therefore the absolute values and the collision energy dependence of the total cross sections simply reflect the long-range behaviour of the excited state potentials.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01425589
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