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  • 11
    In: Faszination Meeresforschung, Bremen : Hauschild, 2006, (2006), Seite 116-122, 3897573105
    In: 9783897573109
    In: year:2006
    In: pages:116-122
    Type of Medium: Article
    Language: German
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  • 12
    In: Faszination Meeresforschung, Bremen : Hauschild, 2006, (2006), Seite 406-409, 3897573105
    In: 9783897573109
    In: year:2006
    In: pages:406-409
    Type of Medium: Article
    Language: German
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  • 13
    Electronic Resource
    Electronic Resource
    Springer
    Journal of neurology 144 (1937), S. 141-159 
    ISSN: 1432-1459
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Zusammenfassung 1. Es wird eine Versuchsanordnung beschrieben, mit der es gelingt, die Schwankungen der Lichtempfindlichkeit über längere Zeit im Dunkelversuch zu messen. 2. Es sind kurzfristige Versuche zur Erfassung der Änderung ungeeignet. Versuche über 1/2 Stunde mit minutlicher Ablesung sind am günstigsten. 3. Man findet normal eine geringe Schwankungsbreite der Empfindlichkeit. Sie beträgt in unseren Versuchen bis zum Doppelten der tiefsten Schwelle. 4. Bei körperlicher Ermüdung erhöht sich die Schwankungsbreite wenig. 5. Bei 30 untersuchten Nervenkranken findet sich teilweise eine viel stärkere Schwankung der Lichtempfindlichkeit. Sie kann bis zum 40fachen des tiefsten Punktes ansteigen. 6. Es gelingt mit dem Verfahren nicht, die Lokalisation der Ermüdung anzugeben.
    Type of Medium: Electronic Resource
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  • 14
    ISSN: 1432-2056
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Chitinase and N-acetyl-β-D-glucosaminidase have been demonstrated in Meganyctiphanes norvegica and in Euphausia superba and partly characterized. The enzymes from both species have broad pH-optima (maxima around pH 5.0) and temperature optima between 40 and 50°C. The enzymes are relatively stable; even at about 45°C half of the enzyme activity is retained after 30 min incubation. The presence of fluoride does not affeet enzymatic activity. Chitinase activity appears in three different molecular masses, N-acetyl-β-D-glucosaminidases in two different forms. pH and temperature optima, thermal stability and kinetic properties of the two enzymes are strikingly similar in the polar E. superba versus the boreal euphausiid M. norvegica. Enzyme activity in the lower temperature range is still high, whereas activation energies are low in both euphausiids. This suggests a functional adaptation to a low temperature range in seawater.
    Type of Medium: Electronic Resource
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  • 15
    ISSN: 1432-2056
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Chitinolytic activity was quantified in euphausiid integuments in relation to moulting. In Euphausia superba, shortly before moult the activity increased in chitinase and N-acetyl-β-D-glucosaminidase to pronounced maxima indicating the onset of massive resorption of cuticular material. Enzymatic activity of E. superba corresponded to values in Meganyctiphanes norvegica, a boreal euphausiid which was investigated for comparison, as well as in insecta. Antarctic krill from winter catches displayed activities comparable to summer material suggesting physiological preparation for moulting. Accordingly, moulting did not cease during winter. Both enzymes were also active in the digestive tract in summer as well as in winter krill: chitin containing food of phyto-and zooplankton origin is digestable. Seasonally stable activities did not point to changes in nutritional preference. In contrast to other crustacea, digestive enzyme activity was not reduced around moult, suggesting a high capacity to continuously utilize food sources including chitin. This property can be linked directly to the high energy need caused by the necessity of constant active swimming in both krill species.
    Type of Medium: Electronic Resource
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  • 16
    ISSN: 1432-2056
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Feeding experiments of 9, 14 and 20 days duration were carried out on the Antarctic krill, Euphausia superba. Two groups were fed with the chitinous diatom Cyclotella cryptica and the non-chitinous green algae Dunaliella bioculata, respectively. A control group remained unfed. The time courses of the activities of endo- and exochitinase in the stomach and the midgut gland were compared with those of the digestive enzymes protease, cellulase (1,4-β-d-glucanase) and laminarinase (1,3-β-d-glucanase). Specific activities of all enzymes were higher in the stomach than in the midgut gland. Characteristic time courses of activity were evident after 4 days. In starved animals, enzyme activities decreased to a minimum after 4 days and recovered within 14 days to initial values. In the stomach, the activities of endo- and exochitinase increased when krill were fed on Cyclotella. For animals fed with Dunaliella, activities stayed constant or decreased slightly. The results confirm chitinases as digestive enzymes and, therefore, the capability of krill to utilize various food sources.
    Type of Medium: Electronic Resource
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  • 17
    ISSN: 1573-5117
    Keywords: Meganyctiphanes norvegica ; respiration ; temperature ; vertical migration ; Kattegat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The Alkor-Deep (140 m), which forms part of a depression system in the northern Kattegat channel east of the island of Læsø (Denmark), is the location of a self sustaining population of Northern krill, Meganyctiphanes norvegica (Euphausiacea). This population is exposed to one of the most pronounced thermal gradients within the distributional range of this pelagic crustacean. During summer, the temperature of the water column ranges between 4 and 6 in the deep to 16 °C near the surface which results in the krill being exposed to temperature differences of 8–10 °C during diel vertical migration. Oxygen consumption rates were used to investigate the physiological adaptation of the animal to such gradients in temperature. The rates were found to increase exponentially from 31 μmol O2 h-1 gdw -1 at 4 °C to 72 μmol O2 h-1 gdw -1 at 16 °C, giving a Q 10-value of 2.0, and indicating that physiological adaptation to varying thermal conditions does not take place. Behavioural adaptations are discussed which may help the krill to cope with large temperature gradients in their environment.
    Type of Medium: Electronic Resource
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  • 18
    Electronic Resource
    Electronic Resource
    Springer
    Neurosurgical review 15 (1992), S. 249-254 
    ISSN: 1437-2320
    Keywords: Brain death ; evoked potentials
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Multimodally evoked potentials were registered in 85 patients who fulfilled the criteria for brain death. While samatosensory and visual evoked potentials have been found to be of limited value for the diagnosis of brain death, the stepwise abolition of brain stem auditory evoked potentials (BAEP) confirmed brain death in 26 out of 85 patients, i. e. 31%. Registration of the abolition of BAEP is concluded to be a safe and acceptable confirmatory test. It is, however, more feasible for institutions, in which BAEP are analysed routinely. In spite of all efforts sequential BAEP could not be used for the diagnosis of brain death in the majority of cases either because of absence of reproducible responses at the initial registration or because the patient was already apnoic at the time of the initial BAEP. Assuming that bilateral preservation of wave I has the same significance as the stepwise abolition of BAEP, since it also proves the integrity of the peripheral receptor, BAEP are relevant for the declaration of brain death in approximately 30% of patients.
    Type of Medium: Electronic Resource
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  • 19
    Publication Date: 2019-09-23
    Description: Calanoid copepods and euphausiids are key components of marine zooplankton communities worldwide. Most euphausiids and several copepod species perform diel vertical migrations (DVMs) that contribute to the export of particulate and dissolved matter to midwater depths. In vast areas of the global ocean, and in particular in the eastern tropical Atlantic and Pacific, the daytime distribution depth of many migrating organisms corresponds to the core of the oxygen minimum zone (OMZ). At depth, the animals experience reduced temperature and oxygen partial pressure (pO2) and an increased carbon dioxide partial pressure (pCO2) compared to their near-surface nighttime habitat. Although it is well known that low oxygen levels can inhibit respiratory activity, the respiration response of tropical copepods and euphausiids to relevant pCO2, pO2 and temperature conditions remains poorly parameterized. Further, the regulation of ammonium excretion at OMZ conditions is generally not well understood. It was recently estimated that DVM-mediated ammonium supply considerably fuels bacterial anaerobic ammonium oxidation – a major loss process for fixed nitrogen in the ocean. These estimates were based on the implicit assumption that hypoxia or anoxia in combination with hypercapnia (elevated pCO2) does not result in a downregulation of ammonium excretion. Here we show that exposure to OMZ conditions can result in strong depression of respiration and ammonium excretion in calanoid copepods and euphausiids from the Eastern Tropical North Atlantic and the Eastern Tropical South Pacific. These physiological responses need to be taken into account when estimating DVM-mediated fluxes of carbon and nitrogen into OMZs.
    Type: Article , PeerReviewed
    Format: text
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  • 20
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    Institut für Meereskunde an der Universität Kiel
    In:  Institut für Meereskunde an der Universität Kiel, Kiel, 7 pp.
    Publication Date: 2015-02-03
    Type: Report , NonPeerReviewed
    Format: text
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