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  • 1
    ISSN: 1432-041X
    Keywords: Ammonia ; Methylamines ; Glutamine ; Nematocytes ; Nerve cells ; Coelenterates ; Hydra ; Hydractinia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Hydrozoa replace used-up nematocytes (cnidocytes) by proliferation and differentiation from interstitial stem cells (i cells). Repeated pulsed exposure ofHydra to elevated levels of unprotonated ammonia leads to successive loss of the various types of nematocytes: first of the stenoteles, then of the isorhizas and finally of the desmonemes. The loss is due to deficits in supply; the number of nematoblasts and differentiating intermediates is reduced. In the hydroidHydractinia the main process leading to numerical reduction was observed in vivo: mature nematocytes as well as precursors emigrate from their place of origin into the gastrovascular channels where they are removed by phagocytosis. This is a regular means by which these animals down-regulate an induced surplus of nematocytes. With lower effectiveness, pulses of methylamine, trimethylamine and glutamine also induce elimination of the nematocyte lineages. In the long term the population of nerve cells, which are permanently but slowly renewed from interstitial neuroblasts, decreases, too. After 2 months of daily repeated treatment the density of the Arg-Phe-amide-positive nerve cells was reduced to 50% of its normal level. Thus, ammonia induces down-regulation of all interstitial cell lineages. The temporal sequence of the ammonia-induced loss reflects the diverse rates with which the various i cell descendants normally are renewed.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Development genes and evolution 199 (1991), S. 370-372 
    ISSN: 1432-041X
    Keywords: Metamorphosis ; Hydractinia echinata (Hydrozoa) ; Metamorphosis inducing factor
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary A metamorphosis-inducing factor was isolated from medium conditioned by either metamorphosing larvae or 3-day postmetamorphic primary polyps. The factor has a molecular weight ≥ 8 kDa and is heatlabile. It does not induce metamorphosis of isolated posterior fragments and is therefore not identical to the internal signal described by Schwoerer-Böhning et al. (1990). The biological significance of the substance is currently unclear, therefore its inducing activity may be a side effect.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-1041
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    European journal of clinical pharmacology 48 (1995), S. 320-320 
    ISSN: 1432-1041
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    BioControl 4 (1959), S. 47-55 
    ISSN: 1573-8248
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Description / Table of Contents: Summary 1. The nest sections of three formicaria ofFormica rufa L. andF. polyctena Först. were heated with an infrared lamp. Characteristic changes in the structure of the detritus dome were obtained by changing the distance of the lamp from the nest. 2. The increase of detritus cannot be used as an accurate measure of colony growth. The building of the detritus dome is largely influenced by climatic factors. 3. The effects of protecting ant colonies by placing wire mesh over the dome are discussed.
    Notes: Résumé 1. Les nids de trois fourmillières deFormica rufa L. etF. polyctena Först. furent irradiés avec une lampe à infra-rouge. Le déplacement de la lampe par rapport au nid a provoqué des modifications caractéristiques dans le mode de construction du dôme de la fourmillère. 2. L'augmentation du volume d'un nid ne peut pas être considérée valablement comme l'indication d'un accroissement de la colonie de fourmis car la construction du dôme de détritus est largement influencée par des facteurs climatiques. 3. Les effets de la protection des nids de fourmis au moyen d'un grillage appliqué sur le dôme sont discutés.
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Naturwissenschaften 45 (1958), S. 196-196 
    ISSN: 1432-1904
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Natural Sciences in General
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    BioControl 5 (1960), S. 81-86 
    ISSN: 1573-8248
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Description / Table of Contents: Riassunto Le differenze morfologiche delle diFormica rufa L. eF. polyctena först. sono descritte brevemente. Si possono separare le due specie per mezzo della pelosità del torace e della testa. Oltre a ciõ tutte le due hanno un odore specifico. I nidi diFormica rufa L. sono in parte monogini e in parte poligini, quelli diFormica polyctena först. sempre poligini. Finora le due specie sono state trapiantate insieme. Esse si combattono quando si incontrano. L'Autore propone di usare per i trapianti solamente laFormica polyctena först. poichè questa specie è in Germania più abbondante dellaFormica rufa poligina.
    Notes: Résumé Les différences morphologiques entre les deFormica rufa L. et celles deF. polyctena först. sont décrites. Les deux espèces sont distinguées par le nombre des poils. En outre les nids de chaque espèce ont une odeur spéciale. Les nids deF. rufa L. sont en partie monogynes et en partie polygynes, ceux deF. polyctena först., le plus souvent polygynes. Jusqu'à présent on a multiplié les deux espèces ensemble. En se rencontrant, elles se combattent. L'auteur propose de multiplier désormais seulementF. polyctena först, parce que cette espèce est plus souvent polygyne queF. rufa.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1432-1955
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Description / Table of Contents: Zusammenfassung Musca domestica L. reagierte unterschiedlich auf die Parasitierung durch die Braconide Aphaereta pallipes (Say). Die verschiedenen Reaktionen waren im wesentlichen mit der Art der Wirtsnahrung korreliert. Daneben finden sich Hinweise, daß auch der Wirtsstamm, dessen Zuchttemperatur, das Alter von Parasit und Wirt und der Eiablageort des Parasiten die Reaktionen beeinflussen. Obgleich die Entwicklung von Parasitenembryonen bereits gehemmt war, ehe sie innerhalb des Wirtes von Melanin eingeschlossen wurden, so verhinderten doch die Parasiten-embryonen und/oder die Wirkung der vor der Eiablage abgegebenen Paralysierungstoxine die normale Entwicklung der Wirte aus sechs Fliegenstämmen. Eine beträchtliche Steigerung der Überlebensrate der Parasiten trat ein, wenn M. domestica-Larven in einem Gemisch chemisch genau definierter Nahrung gezogen wurden.
    Notes: Summary Varying host reaction of the house fly, Musca domestica L., to parasitism by the braconid Aphaereta pallipes (Say) was chiefly correlated with the diet of the host. Some evidence was found that implicated the strain of the host, the rearing temperatures, the ages of the parasitoid and the host, and the site of oviposition. Though development of A. pallipes embryos was inhibited before they became encapsulated with melanin within the host, the presence of the parasitoid and (or) the effect of its paralyzing toxin that was injected into the host just before oviposition prevented normal larval, pupal, or adult development of the six house fly strains tested. A considerable increase of parasitoid survival occurred when M. domestica larvae were reared on a chemically defined diet.
    Type of Medium: Electronic Resource
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  • 9
    Publication Date: 2017-02-14
    Description: The extensive forests that cover the mountains of the Pacific Northwest, USA, modify snow processes and therefore affect snow water storage as well as snow disappearance timing. However, forest influences on snow accumulation and ablation vary with climate, topography, and land cover and are therefore subject to substantial temporal and spatial variability. We utilize multiple years of snow observations from across the region to assess forest-snow interactions in the relatively warm winter conditions characteristic of the maritime and maritime-continental climates. We (1) quantify the difference in snow magnitude and disappearance timing between forests and open areas and (2) assess how forest modifications of snow accumulation and ablation processes combine to determine whether snow is retained longer in the forest or in the open. We find that snow disappearance timing generally ranges from synchronous in the forest and open, to snow persisting up to 13 weeks longer in the open relative to a forested area. However, in locations subject to high wind speeds, differential snow disappearance timing is reversed: snow persists 2-5 weeks longer in the forest. Analysis of snow accumulation and loss through the winter and spring indicate that forest canopy-modulated snow deposition, rather than ablation processes, sets up the difference in snow duration between forests and open. The difference in snow accumulation between open areas and forests is larger than the difference in snow ablation, except at windy sites. Subsequently, differential snow disappearance timing tends toward longer snow retention in the open. The time lag in snow disappearance between the forest and open is then a consequence of the amount of snow remaining and the ablation rate in the open. These findings suggest that improved quantification of forest effects on snow accumulation processes are needed to accurately predict the effect of forest canopy change via harvest or natural disturbance on snow water resources of the Pacific Northwest.
    Print ISSN: 0885-6087
    Electronic ISSN: 1099-1085
    Topics: Architecture, Civil Engineering, Surveying , Geography
    Published by Wiley
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  • 10
    Publication Date: 1995-09-01
    Print ISSN: 0031-6970
    Electronic ISSN: 1432-1041
    Topics: Chemistry and Pharmacology , Medicine
    Published by Springer
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