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  • 1
    ISSN: 1432-136X
    Keywords: Ovary ; Abdominal integument ; Ecdysteroid biosynthesis ; Radioimmunoassay ; Cricket, Gryllus bimaculatus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Ovaries from 4-day-old female adults of Gryllus bimaculatus produce about 5 ng of free and conjugated ecdysteroids per hour during a 16-h incubation in Grace's medium. During incubation of pieces of the abdominal integument together with the adjacent segmental fat body, a net synthesis of moulting hormones is observed (2.3 ng per hour per animal), similar to that in the ovary. Separate incubations of disunited abdominal epidermis and segmental fat body tissue result in much lower rates of ecdysteroid synthesis. Ecdysteroid synthesis in ovarian homogenates is about one-third of that in intact organs. This reduction is due to a lack of conjugate formation in homogenates. Homogenates of the abdominal integument complex are no longer capable of synthesizing ecdysteroids. For both tissues, a de novo synthesis of ecdysteroids is corroborated by following the in vitro incorporation of [14C]-label from cholesterol and [3H]-label from 2,22,25-trideoxyecdysone (5β-ketodiol), respectively, into free ecdysone. The rate of incorporation into ecdysone is only 0.0014% for cholesterol but 0.48% for 5β-ketodiol. Both tissues represent primary sources of ecdysteroids in female adult crickets.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] We used a yeast two-hybrid screen10 to find specific substrates of the c-Met receptor tyrosine kinase. The hybrid bait consisted of the cytoplasmic part of c-Met and the DNA-binding and dimerization domain of LexA, and resulted in interchain phosphorylation of the receptor on tyrosine residues in ...
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 0265-9247
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The c-ros, c-met and c-neu genes encode receptor-type tyrosine kinases and were originally identified because of their oncogenic potential. However, recent progress in the analysis of these receptors and their respective ligands indicate that they do not mediate exclusively mitogenic signals. Rather, they can induce cell movement, differentiation or morphogenesis of epithelial cells in culture. Interestingly, the discussed receptors are expressed in embryonal epithelia, whereas direct and indirect evidence shows that the corresponding ligands are produced in mesenchymal cells. In development, signals given by mesenchymal cells are major driving forces for differentiation and morphogenesis of epithelia; embryonal epithelia are generally unable to differentiate without the appropriate mesenchymal factors. The observed activities of these receptor/ligand systems in cultured cells and their expression patterns indicate that they regulate epithelial differentiation and morphogenesis also during embryogenesis and suggest thus a molecular basis for mesenchymal epithelial interactions.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 4
    Publication Date: 2019-07-17
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , NonPeerReviewed
    Format: application/pdf
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  • 5
    Publication Date: 2013-10-16
    Description: Australian climate-proxy reconstructions based on tree rings from tropical and subtropical forests have not been achieved so far due to the rarity of species producing anatomically distinct annual growth rings. Our study identifies the Australian Red Cedar (Toona ciliata) as one of the most promising tree species for tree-ring research in Australasia because this species exhibits distinct annual tree rings, a prerequisite for high quality tropical dendroclimatology. Based on these preliminary studies, we were able, for the first time in subtropical and tropical Australia, to develop a statistically robust, precisely dated and annually resolved chronology back to AD1854. We show that the variability in ring widths of T. ciliata is mainly dependent on annual precipitation. The developed proxy data series contains both high- and low-frequency climate signals which can be associated with the El Niño Southern Oscillation (ENSO) and the Interdecadal Pacific Oscillation (IPO). A comparison of different data sets (Brisbane precipitation, tree rings, coral luminescence record from the Great Barrier Reef, ENSO and IPO) revealed non-stationary correlation patterns throughout the twentieth century but little instability between the new tree-ring chronology and Brisbane precipitation.
    Type: http://purl.org/escidoc/metadata/ves/publication-types/article
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  • 6
    Publication Date: 2013-10-16
    Description: Tree-ring widths and stable carbon and oxygen isotopes of five European larch trees from Lötschental, Switzerland were investigated for the period 1900–2004. The objective was to test the suitability of each of these parameters for high-frequency climate reconstructions. This is of special interest with regard to the problem of cyclic larch budmoth (LBM) infestations of alpine larch trees. The results clearly demonstrate that tree-ring width chronologies are not suitable for high-frequency reconstructions because infestations lead to variably reduced tree-ring increments, largely suppressing climate signals. On the other hand, the stable isotope chronologies proved less affected by larch budmoth outbreaks, independent of the strength of the infestations. The correlation of the carbon isotopes with summer temperatures was especially high (r = 0.73) and with precipitation lower but nevertheless significant (r = −0.43). Oxygen isotopes were also correlated with summer temperature (r = 0.46); however, a certain perturbation of normal oxygen isotope signatures due to LBM outbreaks was evident. Contrary to tree-ring widths, none of the LBM outbreaks caused a significant disturbance of the current year’s isotopic climate signal and, most importantly, there were no delayed effects in the following years. Thus, stable carbon isotopes in tree-ring chronologies of the European larch provide an excellent opportunity for high-frequency temperature reconstructions.
    Type: http://purl.org/escidoc/metadata/ves/publication-types/article
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  • 7
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    In:  Palaeogeography Palaeoclimatology Palaeoecology ; Year: 2008 ; Volume: 270 ; Issue: 1-2 ; Pages: 116-127
    Publication Date: 2013-10-16
    Description: In tropical Australia, palaeoclimatic proxies derived from tree rings are sought after sources for reconstructing climate variations. However, dendroclimatology has not been widely applied in tropical forests and even less so in the Australian tropics due to the extreme rarity of species producing anatomically distinct annual growth rings. Furthermore, most Australian tree species exhibit rather strong opportunistic growth with non-annual growth zones that are less suitable for dendrochronology. Recent studies on the Australian Red Cedar (Toona ciliata) in the Upper Kangaroo Valley near Sydney revealed that tree-ring based climate reconstructions are feasible with this species. This study moved 2500 km further north and concentrated on the tropical stands of T. ciliata because it is one of the few deciduous tree species in tropical Australia likely characterised by a dormant period of the cambium and thus annual tree rings. Although dendroclimatological studies indicate that some Australian tree species are suitable for reconstructing climate patterns, a well replicated tree-ring record from Far North Queensland has not been developed until now. Tree cores of T. ciliata were developed into a 140-year tree-ring widths index chronology. The analyses showed that the ring-widths indices correlate with March–June precipitation as recorded at Kairi research station. March–June precipitation was reconstructed using the tree-ring data with 35% of the variance explained. The reconstructed series contains both high- and low-frequency climate signals. This suggests that growth of T. ciliata is influenced by climate phenomena of different wave lengths which can be associated with El Niño Southern Oscillation (ENSO) and Interdecadal Pacific Oscillation (IPO).
    Type: http://purl.org/escidoc/metadata/ves/publication-types/article
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  • 8
    Publication Date: 2016-07-12
    Description: A consolidated analysis of the physiologic and molecular responses induced under acid stress in the legume-symbiont model-soil bacterium 〈i〉Sinorhizobium meliloti〈/i〉 Scientific Reports, Published online: 11 July 2016; doi:10.1038/srep29278
    Electronic ISSN: 2045-2322
    Topics: Natural Sciences in General
    Published by Springer Nature
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  • 9
    Publication Date: 2015-04-26
    Description: A thermo-mechanical process consisting of cold rolling and subsequent reversion annealing was applied to high-alloy metastable austenitic CrMnNi steels with different nickel contents. As a result of the reversion annealing ultrafine grained material with a grain size in the range between 500 nm up to 4 ?m were obtained improving the strength behavior of the material. The evolution of the texture of both the cold rolled states and the reversion-annealed states was studied either by X-ray diffraction or by EBSD measurements. The nickel content has a significant influence on the austenite stability and consequently also on the amount of the martensitic phase transformation. However, the developed textures in both steel variants with different austenite stability revealed the same behavior. In both investigated steels the texture of the reverted austenite is a pronounced Bs-type texture as developed also for the deformed austenite
    Print ISSN: 1757-8981
    Electronic ISSN: 1757-899X
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
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