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21.
22.
Nicoletta zini Patrizia Sabatelli Irene Faenza Andrea Ognibene Nadir M. Maraldi 《The Histochemical journal》1996,28(7):495-504
Summary Some key elements of signal transduction have been identified within the nucleus and demonstrated to be responsive to specific
agonists in numerous cell types. In particular, mitogenic stimuli have been reported to induce, a transient increase of the
nuclear phospholipase C β1 activity, causing the release of inositide-derived second messengers, whereas differentiating stimuli induced a decrease
of the enzyme activity and an increase of nuclear phosphatidylinositol 4,5-bisphosphate (PIP2). Recently, we reported evidence, in human osteosarcoma Saos-2 cell lines, on the presence of specific nuclear phospholipase
C isoforms and on the activation of phospholipase C β1 in the nucleus following the exposure to interleukin-1α. In this study we report immunocytochemical ultrastructural evidence on quantitative variations of PIP2 and phospholipase C β1 amounts in the nucleus of Saos-2 cells at different times of exposure to interleukin-1α. After short periods of culture in the presence of the agonist, the intranuclear amount of PIP2 is decreased, while a translocation of phospholipase C β1 occurs from the cytoplasm to the nucleus, in correspondence with the increased hydrolyzing activity of the enzyme. After
longer periods of incubation with interleukin-1α, on the other hand, the intranuclear amount of PIP2 is restored to initial level, while the amount of phospholipase C β1 is increased both at the nuclear and cytoplasmic level, when its activation is no longer effective. The results, compared
with those obtained in other cell types responsive to given agonists, account for a cell-specific modulation of signal transduction
based on polyphosphoinositide breakdown at the nuclear level. 相似文献
23.
Andrea Timcke und Hans-Heiner Bergmann 《Journal of Ornithology》1994,135(1):95-100
Zusammenfassung Der Verbeugungstriller männlicher Brandenten, eine epigame Lautäußerung, weist sowohl in syntaktischen wie auch phonetischen Parametern zyklische jahreszeitliche Veränderungen auf. Die Gesamtdauer der Lautäußerung vergrößert sich allmählich im Laufe des Frühjahrs. Dafür sind eine Verlängerung des tonalen Eingangselements und eine Vermehrung der Elemente der abschließenden Phrase verantwortlich. Dagegen verkürzt sich das 2. Element gleichzeitig. In allen untersuchten Elementen erhöht sich die Tonhöhe parallel zur Verlängerung des Rufes. Diese Veränderungen des Ausdrucksverhaltens geben vermutlich Änderungen innerer Zustandsgrößen wieder.
Seasonally changing bird call: the trill call of male Shelducks (Tadorna tadorna)
Both syntactic and phonetic features of the trill call accompanying the whistle-shake in adult male Shelducks are subject to cyclic annual changes. In the course of spring, the duration of the whole call increases gradually. This is caused by a prolongation of the first call element and insertion of additive elements in the final phrase. In contrast the second element is shortened by about 10 ms. At the same time, the pitch of all measured elements is raised. These findings are discussed in the framework of hormonal regulation and communicative function.相似文献
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25.
Andrea Streng Hans G. Wallraff 《Ethology : formerly Zeitschrift fur Tierpsychologie》1992,91(3):203-219
The role of familiar visual landmarks in pigeon homing is still unsettled. If they are involved, they must be thought to be utilized in parallel with olfactory signals. In order to recognize the effectiveness of either one of the input channels separately, vision and olfaction, it is therefore necessary to interfere with both of them. Pigeons were temporarily deprived of image vision by spectacles made of translucent white paper, producing a condition called V- as compared with the largely unimpaired condition V+. Access to olfactory signals was temporarily prohibited by charcoal filters before release and nasal anaesthesia upon release, resulting in condition O- versus unimpaired smelling of natural air in O+. Prior to the test releases, all the participating pigeons had been made familiar with the two or four test sites (and with other sites in the area) by training flights. According to decreasing levels of initial homeward orientation and homing performance, the four combinations of treatments are to be arranged in the following order: V+O+, V+O-, V-O+, V-O-. In the last type, no trace of initial homeward orientation remained, indicating that at least one of the two input channels need be functional to enable home-related orientation. Over well known terrain, either alone seems to be more or less sufficient. The results are indicative but not definitely conclusive. Effects of visual impairment on behavioural activities in general cannot clearly be separated from orientation-specific effects. Therefore, and because many pigeons refuse to fly in V- condition or fail to provide useful data, we stopped applying this method. 相似文献
26.
Dall'Olio Fabio; Mariani Erminia; Tarozzi Andrea; Meneghetti Alessandra; Chiricolo Mariella; Lau Joseph T. Y.; Facchini Andrea 《Glycobiology》1997,7(4):507-513
The extent of processing of N-linked oligosaccharides and thesialylation of the target cell membranes has been positivelycorrelated with resistance to lysis mediated by NK cells, buta conclusive evidence has never been reached. Colon cancer tissuesexpress an increased activity of ß-ga-lactoside 相似文献
27.
Andrea Robitzki Alexandra Mack Arnaud Chatonnet Paul G. Layer 《Journal of neurochemistry》1997,69(2):823-833
Abstract: The function of the enzyme butyrylcholinesterase (BChE) in the developing and mature brain is still unclear. We have inserted 577 bp of the 5' upstream region plus 106 bp of the exon 1 of the rabbit BChE gene in reverse orientation under control of an SV40 early promoter derivative in an expression vector. This vector was introduced by calcium phosphate-mediated transfection into embryonic chicken retina cells during the first days of reaggregation culture. Depending on the retinal origin, the transfected cell population forms histotypic retina-like spheres, so-called rosetted or stratified retinospheroids. We show that antisense 5'-BChE gene expression decreased the steady-state mRNA level of BChE and the translation of the BChE protein, inhibited proliferation, and accelerated histogenesis in both cellular systems. The pronounced effects of antisense 5'-BChE transfection of spheroids document a key role of BChE during the early reaggregation process of retinal cells, most likely by regulating their growth and differentiation. 相似文献
28.
H. Sinzinger K. Silberbauer A.K. Horsch Andrea Gall 《Prostaglandins & other lipid mediators》1981,21(1):49-51
During successful treatment of peripheral vascular disease with synthetic prostacyclin no alteration in platelet function was reported (1).In 8 patients infused with synthetic prostacyclin continuously for 7 days intraarterially, the platelet function was monitored. Special attention was drawn to the platelet sensitivity in vitro for PGI2, which is discussed as an important factor maintaining the hemostatic balance.In all the patients with peripheral vascular disease between 24 and 48 hours after the beginning of the infusion a sudden decrease in platelet sensitivity accompanied by an increase in platelet count could be seen.These dramatic alterations representing probably a rebound phenomenon occurring during long-term PGI2-treatment might be an explanation for a non-beneficial effect of the treatment and in some cases a limiting factor for the continuation of the infusion itself. It is not clear, if this rebound phenomenon is due to a stimulation of an endogenous inhibitor, lowering the synthesis of a naturally occurring substance acting against this inhibitor or tachyphylaxia. 相似文献
29.
30.
Kathy Darragh Gabriela Montejo‐Kovacevich Krzysztof M. Kozak Colin R. Morrison Clarisse M. E. Figueiredo Jonathan S. Ready Camilo Salazar Mauricio Linares Kelsey J. R. P. Byers Richard M. Merrill W. Owen McMillan Stefan Schulz Chris D. Jiggins 《Ecology and evolution》2020,10(9):3895-3918
In many animals, mate choice is important for the maintenance of reproductive isolation between species. Traits important for mate choice and behavioral isolation are predicted to be under strong stabilizing selection within species; however, such traits can also exhibit variation at the population level driven by neutral and adaptive evolutionary processes. Here, we describe patterns of divergence among androconial and genital chemical profiles at inter‐ and intraspecific levels in mimetic Heliconius butterflies. Most variation in chemical bouquets was found between species, but there were also quantitative differences at the population level. We found a strong correlation between interspecific chemical and genetic divergence, but this correlation varied in intraspecific comparisons. We identified “indicator” compounds characteristic of particular species that included compounds already known to elicit a behavioral response, suggesting an approach for identification of candidate compounds for future behavioral studies in novel systems. Overall, the strong signal of species identity suggests a role for these compounds in species recognition, but with additional potentially neutral variation at the population level. 相似文献