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  • Neurosecretion  (3)
  • Photoperiodic induction  (3)
  • Springer  (6)
  • International Union of Crystallography (IUCr)
  • 1980-1984
  • 1975-1979  (6)
  • 1978  (6)
Collection
Keywords
Publisher
  • Springer  (6)
  • International Union of Crystallography (IUCr)
Years
  • 1980-1984
  • 1975-1979  (6)
Year
  • 1
    Electronic Resource
    Electronic Resource
    Light requirement, phytochrome and photoperiodic induction of flowering of Pharbitis nil Chois (1978)
    Springer
    Planta 141 (1978), S. 1-7 
    Details
    ISSN: 1432-2048
    Keywords: Flowering ; Pharbitis ; Photomorphogenesis ; Photoperiodic induction ; Phytochrome
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract For dark-grown seedlings of Pharbitis nil capacity to flower in response to a single inductive dark period was established by 24 h white, far-red (FR) or ruby-red (BCJ) light and by a skeleton photoperiod of 10 min red (R)-24 h dark-10 min R. FR alone was ineffective without a brief terminal (R) irradiation, confirming that the form of phytochrome immediately prior to darkness is a crucial factor for flowering in Pharbitis. The magnitude of the flowering response was significantly greater after 24 h FR or white light (WL) (at 18° C and 27° C) than after two brief skeleton R irradiations, but the increased flowering response was not attributable to photosynthetic CO2 uptake because this could not be detected in seedlings exposed to 24 h WL at 18° C. Photophosphorylation could have contributed to the increased flowering response as photosystem I fluorescence was detectable in plants exposed to FR, BCJ, or WL, but there were large differences between flowering response and photosystem I capacity as indicated by fluorescence. We conclude that phytochrome plays a major role in photoresponses regulating flowering. There was no simple correlation between developmental changes, such as cotyledon expansion and chlorophyll formation during the 24-h irradiation period, and the capacity to flower in response to a following inductive dark period. Changes in plastid ultrastructure were considerable in light from fluorescent lamps and there was complete breakdown of the prolamellar body with or without lamellar stacking at 27 or 18° C, respectively, but plastid reorganization was minimal in FR-irradiated seedlings.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00387736
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  • 2
    Electronic Resource
    Electronic Resource
    Light requirement, phytochrome and photoperiodic induction of flowering of Pharbits nil Chois (1978)
    Springer
    Planta 141 (1978), S. 9-14 
    Details
    ISSN: 1432-2048
    Keywords: Flowering ; Pharbitis ; Photoperiodic induction ; Phytochrome ; Spectrophotometry (phytochrome)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The low chlorophyll content of cotyledons of Pharbitis nil grown for 24 h in far-red light (FR) or at 18° C in white light from fluorescent lamps (WL) allows spectrophotometric measurement of phytochrome in these tissues. The Δ(ΔA) measurements utilize measuring beams at 730/802 nm and an actinic irradiation in excess of 90 s. The constancy of the relationship between phytochrome content and sample thickness confirms that, under these conditions of measurement, a true maximum phytochrome signal was obtained. These techniques have been used to follow changes in the form and amount of phytochrome during an inductive dark period for flowering. Following exposure to 24h WL at 18° C with a terminal 10 min red (R), Pfr was lost rapidly in darkness and approached zero in less than 1 h; during this period there was no change in the total phytochrome signal. Following exposure to 24 h FR with a terminal 10 min R, Pfr approached zero in 3 h, and the total phytochrome signal decreased by about half. The relevance of these changes to photoperiodic time measurement is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00387737
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  • 3
    Electronic Resource
    Electronic Resource
    Light requirement, phytochrome and photoperiodic induction of flowering of Pharbitis nil Chois (1978)
    Springer
    Planta 141 (1978), S. 15-22 
    Details
    ISSN: 1432-2048
    Keywords: Flowering ; Pharbitis ; Photoperiodic induction ; Phytochrome ; Spectrophotometry (phytochrome)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract During an inductive dark period for flowering, changes in phytochrome have been followed in cotyledons of Pharbitis nil seedlings using a spectrophotometric and a physiological technique. There was agreement between the two techniques, both indicating a rapid lowering of the levels of the far-red-absorbing form of the pigment (Pfr) during the first 30–90 min of darkness. Thus, Pfr could provide the cue which signals the beginning of darkness and the length of the critical dark period was, in some instances, correlated with the time of Pfr disappearance. However, there was no correlation with another indicator of photoperiodic time measurement, the time in darkness at which a brief night interruption becomes inhibitory to flowering. These results imply that the transition from light to darkness is not signalled by the disappearance of Pfr. However, the involvement of other photoreceptors seems unlikely. Thus, some mode of phytochrome action other than a simple Pfr-mediated response may be involved in the light/dark-sensing reactions of photoperiodism
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00387738
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  • 4
    Electronic Resource
    Electronic Resource
    Scanning and transmission electron microscopy of the subfornical organ of the grass frog (Rana pipiens) (1978)
    Springer
    Cell & tissue research 186 (1978), S. 361-374 
    Details
    ISSN: 1432-0878
    Keywords: Subfornical organ ; Circumventricular organs ; CSF-contacting neurons ; Encephalo-chromaffin cells ; Neurosecretion ; Rana pipiens
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The ventricular surface of the subfornical organ of the frog is made up of ependymal cells with numerous apical microvilli, occasional cytoplasmic protrusions and many vacuoles projecting into the lumen of the third ventricle. Between these cells dendrites of cerebrospinal fluid-contacting neurons reach the ventricle to terminate in bulbous enlargements. In addition, flask-shaped encephalo-chromaffin cells, containing granulated vesicles and aggregates of filaments in their cytoplasm, project into the cerebrospinal fluid. Surrounding the centrally located capillaries are enlarged dendrites and axons of heterogeneous morphology, some of which appear to originate within the subfornical organ, intermingled with dendrites and axons of normal structure. The glial cells in this region, especially the microglial cells, often contain large lipofuscin inclusions, suggestive of degeneration and subsequent phagocytosis of some of the enlarged dendrites and axons. The normally scarce neurosecretory peptidergic axons become more evident and form typical Herring bodies in stalk-transected animals. Neuronal perikarya of varying morphology are predominantly located peripheral to the region of enlarged dendrites and axons. Supraependymal macrophages are particularly numerous on the subfornical organ.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00225544
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  • 5
    Electronic Resource
    Electronic Resource
    Structural re-evaluation of the neurosecretory system in the crayfish eyestalk (1978)
    Springer
    Cell & tissue research 190 (1978), S. 235-246 
    Details
    ISSN: 1432-0878
    Keywords: Neurosecretion ; Cobalt backfilling ; Crustacea ; Sinus gland ; X organ
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The topography of the neurosecretory system in the decapod eyestalk has not been precisely delineated with light microscopy. Cobalt iontophoresis and electron microscopy have proved useful in clarifying the microstructure of this system. The sinus gland (sg) of the crayfish eyestalk consists of aggregated axon terminals which end at or near the blood space, lontophoresing cobalt back through the cut base of the sinus glands reveals proximal cell bodies in the eyestalk only in the X organ (Xo) region. Electron microscopy demonstrates that axons from about 115 neurosecretory cell bodies in the Xo form the Xo-sg tract. Intermingled with these Xo somata are smaller non-neurosecretory cell bodies which do not send axons into the sinus gland. One of these exhibits catecholamine fluorescence. Backfilling also reveals a second group of fibres which run from the brain along the optic tract and into the sinus gland. These brain-sg fibres are smaller in diameter than Xo-sg axons and lack neurosecretory vesicles. From these fibres collaterals extend into the eyestalk neuropil, especially in the proximity of the visual elements. The possible function of these non-neurosecretory processes within the sinus gland is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00218172
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  • 6
    Electronic Resource
    Electronic Resource
    Fine structural and cytochemical study of the innervation of smooth muscle in an amphibian (Bufo marinus) lung before and after denervation (1978)
    Springer
    Cell & tissue research 194 (1978), S. 419-432 
    Details
    ISSN: 1432-0878
    Keywords: Lung ; Bufo marinus ; Innervation ; Adrenergic nerves ; Neurosecretion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The innervation of the toad (Bufo marinus) lung was studied with transmission electron microscopy and fluorescence techniques, both before and after 12 or 20 days close vagosympathetic denervation. Four cytologically distinct types of neuronal processes were recognised, in relation to the visceral muscles of the lung. These were described as cholinergic, adrenergic, nonadrenergic/non-cholinergic (NANC) and sensory on the basis of the characteristics of their vesicular content and cytochemical reactions. An apparent efferent innervation of visceral smooth muscle was achieved by NANC (50%), cholinergic (25%) and adrenergic (25%) fibres. A few sensory fibres were also present. After denervation only NANC fibres persisted, showing that the cell bodies of these fibres were intrapulmonary. The vascular smooth muscle was supplied by cholinergic, adrenergic and sensory fibres. In the walls of the proximal branches of the pulmonary artery were fibres containing large dense-cored vesicles. These profiles, which were associated with the vasa vasorum, were similar to neurosecretory fibres. After denervation all neural profiles associated with the vasculature had degenerated. The observations suggest that vagal vasodepressor effects in the toad lung are mediated indirectly through relaxation of visceral muscle strands which in their contracted state compress vascular channels.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00236163
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