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1.
Prof. L. Vollrath M. Karasek B. Kosaras J. Kunert-Radek A. Lewinski 《Cell and tissue research》1985,242(3):607-611
Summary Previous studies have shown that the synaptic ribbons (SR) and spherules (SS) of the mammalian pineal gland may respond differently under physiological and various experimental conditions. The aim of the present study was to gain insight into the mechanisms that may be responsible for the numerical changes of these organelles during a 24-h cycle. As the possibility exists that the structures are influenced by substances synthesized within the pinealocyte, rat pineal glands were cultured with and without added melatonin or serotonin, using an experimental protocol such that the addition of melatonin and serotonin mimicks the circadian changes of the respective substances within the pineal. The tissue was processed for electron microscopy and the numbers of SR and SS were counted in a unit area of pineal tissue. The results obtained indicate that melatonin added to the incubation medium increases the number of SR in the first half of the night; serotonin decreases SR numbers in the morning. SS numbers, by contrast, decrease following melatonin administration in the afternoon, and increase in the morning following serotonin administration. It thus appears that the numbers of SR and SS are influenced by melatonin and serotonin and that the two structures are regulated by differential, but nevertheless biochemically closely related mechanisms.Financial support of the Deutsche Forschungsgemeinschaft (Schwerpunktprogramm Neuroendokrinologie, Vo 135/8-4), the Polish Academy of Sciences (Research Program 10.4.04.6), and the Freunde der Universität Mainz e.V. is gratefully acknowledged.On leave from Department of Anatomy, University Medical School, Pécs, Hungary 相似文献
2.
Fritz Vollrath 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1986,159(2):275-280
summary The effect of gravity on the web building behaviour of the common garden spiderAraneus diadematus was studied in three ways: (i) frames with partially completed vertical webs were swivelled into a horizontal position, (ii) by rotating frames with spiders in a vertical klinostat (1 rpm), and (iii) by vertically rotating a partially completed web treadmill fashion keeping the building animal in a certain position in space.(i) In the horizontal, radial wheels are not constructed, however, a more or less irregular spiral is added to a completed wheel; (ii) in the klinostat the radial wheel lacks the up/down distinction of normal webs, and the spiral is irregular; (iii) in the treadmill the spiral course is abnormal, and the degree of deviation depends on the position of the animal. If the body axis is parallel to gravity the spiral path deviates to both sides of the norm. In ag perpendicular body position the path deviates predominantly to one side, spiralling sharply inwards towards the hub. The observations suggest that the cyclic changes in the body position of spiral-buildingAraneus are an important component of the animal's orientation during this phase of web-construction. 相似文献
3.
Summary In the goldfish, Carassius auratus, morphological and functional aspects of the pituitary gland were studied at the ultrastructural level and six cell types could be distinguished in the pars distalis. Acidophilic cells of the rostral pars distalis were identified as prolactin cells, the chromophobic cells of the rostral pars distalis as ACTH cells, the non-globular basophilic cells of the rostral and the proximal pars distalis as TSH cells, the globular basophils of the proximal pars distalis as gonadotropic cells and the acidophils of the proximal pars distalis as somatotrophs.Besides some of the well established criteria of morphological and functional identification of different cell types, two new approaches have been used in the present study. One was to express the electron density of secretory granules objectively by means of a photometric method. It was found that both types of acidophilic cells which produce the proteohormones prolactin and somatotropin respectively, had granules with the highest electron densities. The basophilic cells producing the glycoproteins gonadotropin and TSH respectively, possessed granules of intermediate electron density whereas the chromophobic cells storing the peptide hormone ACTH had granules of lowest densities. The second new approach was the administration of the synthetic mammalian releasing hormones LH-RP and TRF, which helped in identifying gonadotropic and thyrotropic cells respectively. In the goldfish there is evidence for the presence of only one type of gonadotropic cell.Supported by a grant of the Science Research Council of Great Britain to Professor Sir Francis Knowles, F.R.S. The electron microscope used was provided by the Medical Research Council of Great Britain. The integrating photometer IPM2 was kindly on loan from Messrs. Carl Zeiss, Oberkochen, Germany. For technical advice we are greatly indebted to Mr. P. K. Kaul, B. E., M.I. Struct. E., C. Eng. 相似文献
4.
5.
Lutz Vollrath 《Cell and tissue research》1969,99(1):146-152
Zusammenfassung In der Neurohypophyse fetaler und neugeborener Ratten entsteht die Mehrzahl der synaptischen Bläschen aus Erweiterungen der Neurotubuli. Ferner können pinocytotische Bläschen als synaptische Vesikel imponieren. Die Bläschenbildung aus Membranen von Elementargranula (vgl. Herlant, 1967) tritt dagegen in den Hintergrund. Ein Auftreten von Vesikeln im Innern von Elementargranula wurde nicht beobachtet.
Mit Unterstützung durch die Deutsche Forschungsgemeinschaft. 相似文献
The origin of synaptic vesicles in neurosecretory axons
Summary In the neurohypophysis of fetal and newborn rats the majority of synaptic vesicles originate from dilatations of neurotubuli. Moreover, pinocytotic invaginations give rise to synaptic vesicles. Evaginations of elementary granule membranes, as described by Herlant (1967), are seldom to be found and do not seem to play an important role in the formation of synaptic vesicles. The occurrence of vesicles within elementary granules was not observed.
Mit Unterstützung durch die Deutsche Forschungsgemeinschaft. 相似文献
6.
Abstract: Cyclic GMP (cGMP) formation in rat pinealocytes is regulated through a synergistic dual receptor mechanism involving β-and α1 -adrenergic receptors. The effects of N -monomethyl- l -arginine (NMMA), which inhibits nitric oxide (NO) synthase and NO-mediated activation of cytosolic guanylate cyclase, and methylene blue (MB), which inhibits cytosolic guanylate cyclase, were investigated in an attempt to understand the role of NO in adrenergic cGMP formation. Both NMMA and MB inhibited β-adrenergic stimulation of cGMP formation as well as α1 -adrenergic potentiation of β-adrenergic stimulation of cGMP formation, whereas they had no effect in unstimulated pinealocytes. The inhibitory action of NMMA was antagonized by addition of l -arginine. On the basis of these findings it can be concluded that the adrenergic stimulation of cGMP formation involves NO synthesis followed by activation of cytosolic guanylate cyclase. 相似文献
7.
MinCD-independent inhibition of cell division by a protein that fuses MalE to the topological specificity factor MinE.
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We report that MinE, the topological specificity factor of cell division in Escherichia coli, inhibits septation when fused to the C terminus of the maltose-binding protein MalE. This contrasts with overexpression of MinE alone, which affects growth but has no effect on division. Inhibition by MalE-MinE was minCD independent and depended on MinE segments involved in dimerization and prevention of MinCD division inhibition. The SOS and the heat shock responses were not involved, suggesting that the inhibition comes from a direct interaction of MalE-MinE with the septation apparatus. MalE-MinE lethality was suppressed by overexpression of ftsZ, as well as by overexpression of ftsN, a suppressor of temperature-sensitive mutations in genes ftsQ, ftsA, and ftsI. We also report that high-level synthesis of MalE disturbs nucleoid partitioning. 相似文献
8.
Summary In the present study an attempt was made to demonstrate melatonin in the rat pineal gland by means of immunohistochemistry. The anti-body used was raised against 5-methoxy-N-acetyltryptophan which is chemically similar to melatonin. Specific fluorescence was demonstrable only in pineals from rats killed during the night, when melatonin formation is high. It was restricted to parenchymal cells lying in a marginal zone of the organ. These results are discussed in relation to a subdivision of the pineal parenchyma into cortical and medullary areas.Supported by a grant of the Deutsche Forschungsgemeinschaft (VO 135/4) within the Schwerpunktprogramm Neuroendokrinologie 相似文献
9.
A Bredel-Geissler U Karbach S Walenta L Vollrath W Mueller-Klieser 《Journal of cellular physiology》1992,153(1):44-52
The oxygen consumption rate, proliferative activity, and morphology of EMT6/Ro mouse mammary sarcoma cells in monolayer and multicellular spheroid culture have been investigated in a comparative study. During the transition of monolayer cells from the exponential into the plateau growth phase, there is a distinct decrease in the cellular volume that is associated with a corresponding decrease in the proliferative and respiratory activity of the cells. The decline in cell volume is mainly due to a decrease in the content of cytoplasm, whereas the size of the nucleus is only slightly reduced. A concomitant decrease in the number of mitochondria per cell obviously accounts for the reduction in cellular oxygen uptake. Despite a continuous decrease of cell proliferation from the surface to interior regions of EMT6 spheroids reflected by a gradient in tritiated thymidine labeling, volume-related oxygen consumption is rather uniform in viable regions of these aggregates. The finding can be explained by the results of the morphometric evaluation showing a uniform volume density of mitochondria, i.e., of oxygen-consuming sites within these spheroids. 相似文献
10.
Rainer Spessert Katja Heil Braj B. P. Gupta Lutz Vollrath 《Journal of neurochemistry》1992,59(6):2081-2086
Various parameters of the rat pineal gland display a 24-h rhythm. However, nothing is known about possible 24-h variations in cyclic GMP (cGMP) metabolism. In the present study, 24-h variations in pineal gland cGMP accumulation were investigated by determining the increase in cGMP level with and without inhibitors of phosphodiesterase at different time points over a light/dark cycle (12/12 h). Furthermore, the activity of guanylate cyclase (GC) was determined under substrate-saturated conditions regarding the cytosolic and particulate forms of the enzyme. It has been found that cGMP accumulation and GC activity display biphasic 24-h variations with two peaks--one approximately 7 h after lights "on" and the other approximately 7 h after lights "off." The activity of cytosolic GC remains unchanged in the presence of the nitric oxide (NO) synthesis inhibitor N-monomethyl-L-arginine, indicating that 24-h variations in the activity do not reflect changes in the synthesis of the GC stimulator NO. 相似文献