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  • 1
    Electronic Resource
    Electronic Resource
    Responsiveness of Pineal N-Acetyltransferase and Melatonin in the Cotton Rat Exposed to Either Artificial or Natural Light at Night (1985)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of pineal research 2 (1985), S. 0 
    Details
    ISSN: 1600-079X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: In three separate experiments, the effect of acute exposure to either artificial or natural light during darkness of pineal N-acetyltransferase (NAT) activity and melatonin content was studied in the cotton rat (Sigmodon hispidus). The exposure of animals to an artificial-light irradiance of 160,000 μW/cm2 during darkness for either 1 s, 5 s, or 30 min was followed by a precipitous decline in pineal NAT activity and melatonin content when measured at either 15 or 30 min after light onset. When cotton rats were acutely exposed to light at night for 5 s, irradiances of either 3.2, 32, 320, and 3,200 did not suppress either pineal NAT or melatonin 30 min later; however, if the 5-s exposure had an irradiance of either 32,000 or 160,000 μW/cm2, the pineal enzyme activity and indole content were depressed. Moonlight, which had a maximal irradiance of 0.32 μW/cm2, was unable to suppress pineal NAT activity and melatonin content even when the animals were exposed to the moonlight for 30 min. The treatment of cotton rats with either norepinephrine or its agonist, isoproterenol, before their exposure to light at night retarded slightly the suppressive effect of light on the pineal constituents measured. Also, these drug treatments suppressed the pre-exposure levels of both NAT activity and melatonin content in the cotton rat pineal gland.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1600-079X.1985.tb00717.x
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  • 2
    Electronic Resource
    Electronic Resource
    Pinealocyte subsurface cisterns II: Influence of time of day, sympathectomy, and castration (1991)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of pineal research 10 (1991), S. 0 
    Details
    ISSN: 1600-079X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Heinzeller T, Tutter I. Pinealocyte subsurface cisterns 11: Influence of time of day, sympathectomy, and castration. J Pineal Res 199 1 : 10: 84-90.〈section xml:id="abs1-1"〉〈title type="main"〉Abstract:Subsurface cisterns (ssc) of the gerbil pinealocyte were studied by electron microscopic morphometry taking account of different external influences: time of day, sympathetic deafferentation, castration with or without substitution of testosterone. Male individuals of Meriones unguiculatus, aged 150 days, were used. Though ssc number is invariant with respect to the light-dark cycle, ssc size follows a highly significant sinusoid curve. The largest ssc were found in the afternoon, the smallest ones in the early morning. Bilateral resection of the superior cervical ganglia reduces the density of pinealocyte ssc markedly, and their size is maximal or, in relation to the scaled-down cell, unusually large. Castration with or without application of testosterone propionate does not alter pinealocyte ssc, neither with respect to density nor size. From these experimental data it is concluded that pinealocyte ssc may play a supportive role in the regulation of pinealocyte sensitivity, in so far as it depends on receptors located in the cell membrane.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1600-079X.1991.tb00015.x
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  • 3
    Electronic Resource
    Electronic Resource
    Pinealocyte subsurface cisterns I: Cytologieal aspects including three-dimensional structure (1991)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of pineal research 10 (1991), S. 0 
    Details
    ISSN: 1600-079X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Tutter I, Heinzeller T, Aschauer B. Pinealocyte subsurface cisterns I: Cytological aspects including three-dimensional structure. J Pineal Res 199 1 : 10:7&83.〈section xml:id="abs1-1"〉〈title type="main"〉Abstract:Subsurface cisterns (ssc) in the pineal gland of Meriones unguiculatus have been characterized with transmission electron microscopy, freeze-fracture, morphometry, and three-dimensional reconstruction. Subsurface cisterns (which are observed only in pinealocytes and never in gliocytes) are cisterns of the endoplasmic reticulum (ER) approaching the plasmalemma at a distance of 15–20 nm. Freeze-fracture preparations show that except for some ribosomes at the cytoplasmic face, the cistern membranes as well as the related portions of the plasmalemma are free of special or specifically arranged particles or pores. All ssc have a lumen of 15–20 nm width and underlie 5.6% of the plasmalemma in a single layer; neither collapsed types nor stacks of ssc could be observed. As seen from reconstructions, large ssc are fenestrated and are situated preferentially in regions where the neighboring pinealocyte also bears large ssc. As a consequence, double-sided ssc, which can be observed in sections of (mostly large) ssc, are not a random phenomenon. In regions of the large ssc, adhering junctions are also concentrated. Tubules of 20-nm diameter link ssc with deeper parts of the ER, particularly with the perinuclear cistern and with the tubulo-cisternal network at the trans-side of the Golgi apparatus. Besides ssc proper, a lot of small endplates of ER-tubules are seen close to the plasmalemma. It is suggested that ssc form by the widening and fusing of such ER-tubules and decrease by retraction of ER-tubules from the cell surface.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1600-079X.1991.tb00014.x
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  • 4
    Electronic Resource
    Electronic Resource
    Pinealocyte subsurface cisterns III: Storage of calcium ions and their probable role in cell stimulation (1991)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of pineal research 10 (1991), S. 0 
    Details
    ISSN: 1600-079X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Tutter I, Heinzeller T, Seitz-Tutter D. Pinealocyte subsurface cisterns 111: Storage of calcium ions and their probable role in cell stimulation. J Pineal Res 1991:10:91-99.〈section xml:id="abs1-1"〉〈title type="main"〉Abstract:Different techniques for the ultrastructural demonstration of calcium have been applied to the pineal gland of Meriones unguiculatus, attention being focussed on the endoplasmic reticulum (ER) and its subsurface cisterns (ssc). By means of a “loading” method [Walz, 1982; Wakasugi et al, 1982] it is shown that the pinealocyte ER-ssc system sequesters calcium with dependency on ATP. Furthermore, a modification of the method of Duce and Keen [1978] is presented which turned out a) to be sensitive enough to demonstrate the cell's own low amounts of calcium as fine granular precipitates, and b) to preserve ultrastructure sufficiently. This method rendered possible comparison of the calcium distribution inside pinealocytes of the following groups: animals fixed during daytime, animals fixed at night, animals fixed at night with prior exposure to bright white light, animals fixed at night but injected at the end of the preceding light period with a pharmacon known to prevent the release of calcium from the ER of muscle fibers (Dantrolen). In contrast to the daytime findings, the pinealocyte ER-ssc system at night is free of precipitable calcium; nocturnal illumination induces reacquisition, Dantrolen hinders nocturnal depletion. From the nocturnal coincidence of pinealocyte activity and calcium release from ssc, and from other cytological and experimental data, it is concluded that the functional significance of ssc refers to the regulation of pinealocyte sensitivity. Vice versa, pinealocyte activity may influence ER expansion and ssc size via the calcium-dependent stability of microtubules.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1600-079X.1991.tb00016.x
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  • 5
    Electronic Resource
    Electronic Resource
    Impact of Psychosocial Stress on Pineal Structure of Male Gerbils (Meriones unguiculatus, Cricetidae) (1985)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of pineal research 2 (1985), S. 0 
    Details
    ISSN: 1600-079X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Stress responses were investigated in 5-month-old male gerbils. Breeders having no pubescent litters served as controls. The first experimental group never left their parents’cage and were thereby fought by higher-ranking males; the second and third groups were stressed for a week by four daily 1-minute encounters with trained fighters, the second group during daytime, the third during the dark period. The first and second groups developed signs of gonadal regression, the third did not. The adrenals of the first group weighed the same as those of controls; the adrenals of both other groups were increased in weight. In the adrenal medulla of all experimental groups, a large number of cells were densely packed with noradrenaline-containing vesicles. In each experimental group the pineal changes included a remarkable decrease in nuclear size of pinealocytes, an increased number of colloidal cysts, and a reduction of that portion of the plasmalemma that is lined by subsurface cisterns. All these changes are interpreted in terms of pineal activation, as are the increased number of membrane whirls found in the first group. The third group exhibited an additional decrease in the size of mitochondria and in the number of “synaptic” structures. This finding and the day-night differences in the gonadal response indicate that stress interferes with the metabolic cyclicity of the pineal gland. However, it remains indiscernible whether the pineal stress reaction signals a general activation of the gland or a change in it's temporal activity patterns.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1600-079X.1985.tb00635.x
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  • 6
    Electronic Resource
    Electronic Resource
    Daily release of neurosecretory material produced in the pars intercerebralis ofApis mellifica L. with and without training to a foraging schedule (1978)
    Springer
    Journal of comparative physiology 126 (1978), S. 327-331 
    Details
    ISSN: 1432-1351
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The amount of neurosecretory material was measured in the brains of bees which had been used in a previous study (Vogel et al., 1977) for a determination of the rate of protein synthesis in the pars intercerebralis (PI). The brains of bees trained to short feeding periods contain significantly lower amounts of neurosecretory material than those of bees flying the whole day. The amount of stored material appears to decrease as the reinforcement of training is extended. The daily changes in the storage of secretory material in the PI and corpora cardiaca (CC) show no direct correlation with flying activity, either in trained or in untrained bees. Combining the data on protein synthesis with that on amounts of secretory material in the PI and CC, and taking into account the axonal flow conditions from the PI to the CC, the release of the Pi-material is estimated. These release curves correspond to the temporal activity pattern in all experimental groups.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00667102
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  • 7
    Electronic Resource
    Electronic Resource
    Daily protein synthesis in the pars intercerebralis and corpora allata ofApis mellifica L. with and without training to a foraging schedule (1977)
    Springer
    Journal of comparative physiology 118 (1977), S. 51-60 
    Details
    ISSN: 1432-1351
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The rate of protein synthesis by the neurosecretory cells in the pars intercerebralis and in the corpora allata was determined by autoradiography. Bees that forage throughout the day display a daily rhythm in that rate; the synthesis curve could be shifted considerably in each of two different training experiments. The total amount of protein synthesized per day is distinctly greater for bees that collect all day than for those with activity limited by the training schedule. The corpora allata also exhibit a daily rhythm in protein synthesis, and this too can be altered by training. The relationship to collecting activity are less clear than in the case of the pars intercerebralis, but are similar in direction of shift.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00612336
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  • 8
    Electronic Resource
    Electronic Resource
    Mechanical, sensory and glandular structures in the tarsal unguitractor apparatus of Chironomus riparius (Diptera, Chironomidae) (1989)
    Springer
    Zoomorphology 109 (1989), S. 71-78 
    Details
    ISSN: 1432-234X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The legs of chironomid midges from a laboratory colony were examined in the region of the joint between the fifth tarsal segment and the pretarsus, especially the surface of the unguitractor and the manner in which the unguitractor fits into a ventromedian groove in the edge of the tarsus when the joint is flexed. The region was reconstructed from serial sections to clarify the spatial relations of the internal structures to one another and to the external structures. Ultrastructural characteristics of the cells and cuticle suggest a secretory function of the unguitractor. An amphinematic scoloparium is suspended between the point at which the unguitractor attaches to its tendon and the transverse diaphragm within the tarsus. This mechanoreceptor could serve as a proprioceptive sensor of the position of unguitractor and tarsus; it could also be an exteroceptor, sensing vibration in the substrate and/or the air. In the context of functional morphology, the clamping of the unguitractor in the ventral hollow in the tarsus could have the effect of resetting the sensitivity of the sensor. On the other hand, this arrangement could also simply act as an energy-saving means of fixing the claws in the grasping position for long periods.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00312312
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  • 9
    Electronic Resource
    Electronic Resource
    Second-order ocellar neurons in the brain of the honeybee (Apis mellifera) (1976)
    Springer
    Cell & tissue research 171 (1976), S. 91-99 
    Details
    ISSN: 1432-0878
    Keywords: Ocelli ; Honeybee ; Central projections ; Procion Yellow
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Electrophoretic injection of Procion Yellow M-R4 into the ocellar tract of the worker bee has revealed the following: Two types of giant axon run from the lateral ocellus to the circumesophageal neuropile, where one branches ipsilaterally and the other contralaterally. A third type comes from the median ocellus and can be traced into the cervical connectives. The largest dendritic complex is in the circumesophageal neuropile; in addition, fiber endings have been demonstrated in the following areas: in the subretinal region, along the optic commissure, in the medulla interna, in the subesophageal ganglion and between the neurosecretory cells of the pars intercerebralis. — The giant fibers are enclosed in a glial sheath. Three types of cell body are described. One is associated with the glia; another, larger cell type comprises giant-axon somata. The third type of cell is small, and cannot yet be identified. Some of the histological results are discussed with respect to the possible function of the ocellus.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00219702
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  • 10
    Electronic Resource
    Electronic Resource
    kunstformen der natur (1992)
    Weinheim : Wiley-Blackwell
    Biologie in unserer Zeit 22 (1992), S. 317-317 
    Details
    ISSN: 0045-205X
    Keywords: Life and Medical Sciences
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/biuz.19920220606
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