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  • Springer  (1,496)
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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Helgoland marine research 24 (1973), S. 78-81 
    ISSN: 1438-3888
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Summary 1. Rates of net photosynthesis and respiration were determined in situ forTridacna and coral species and their contained zooxanthellae at depths from 9 to 18 m. 2. Integrated daily total net photosynthesis to respiration ratios (P/R ratio) were calculated from these data to obtain the potential contribution of algal photosynthesis to the energy budget of the coral-algal symbiotic association. 3. The integrated daily P/R ratios varied between 0.79 and .89. Maximum ratios of photosynthesis to respiration rates ranged from 1.15 forMussa arrgulosa to 2.91 forManicina areolata. 4. Similar measurements were made on mixed benthic communities off southeastern Florida (USA) in a clean, unpolluted area and in an area influenced by the effluent of Biscayne Bay (USA). Very significant differences were found.
    Notes: Kurzfassung Im Rahmen mehrerer amerikanischer Unterwasser-Forschungsprogramme wurden Stoffwechseluntersuchungen in verschiedenen Korallenriffen an Benthostieren durchgeführt, die in symbiotischer Partnerschaft mit Zooxanthellen leben. An Korallen- undTridacna-Arten wurden in situ die Beziehungen zwischen Nettophotosynthese und Sauerstoffverbrauch (P/R-Verhältnis) gemessen. Als Maximalwert wurde beiManicina areolata ein P/R-Verhältnis von 2,9 ermittelt. Die auf einen Zeitraum von 24 Stunden bezogenen Durchschnittswerte lagen zwischen 0,79 und 0,89. Es wurde festgestellt, daß die photosynthetische Aktivität der Korallen in verunreinigten Riffgebieten stark absinkt.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1572-9028
    Keywords: enantioselective hydrogenation ; platinum ; cinchonidine ; catalyst modifier ; pyruvate hydrogenation ; MCM-41 ; Pt-MCM-41 preparation ; Pt-MCM-41 characterisation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Pt-MCM-41 catalysts having loadings of up to 2% Pt have been synthesised using three strategies: (i) direct synthesis from a Pt2+-containing gel, (ii) exchange of Na+ in Al-MCM-41 (containing 8% aluminium) for Pt2+, (iii) exchange of H+ in H-MCM-41 (containing 1% aluminium) for Pt2+. HRTEM confirmed the retention of the mesoporous structure in the active catalysts and gave information on Pt particle size and location. 27Al NMR provided information on the movement of aluminium within the structure during catalyst preparation. Enantioselective hydrogenation of methyl and ethyl pyruvate was catalysed by cinchonidine-modified Pt-MCM-41 at 293 K and elevated hydrogen pressures; performance was compared to that provided by the standard reference catalyst EUROPT-1. Catalysts prepared by strategies (i) and (ii) performed best, giving values of the enantiomeric excess comparable to those afforded by EUROPT-1 at rates moderated by an order of magnitude by mass transfer effects. Performance was impaired when Pt particle size in the mesopores was so small that conditions favoured racemic reaction.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 263 (1991), S. 201-205 
    ISSN: 1432-0878
    Keywords: Hyaluronan (hyaluronic acid) ; Hyaluronic acid-binding protein ; Microwave-fixation ; Immunohistocytochemistry ; Striated muscle ; Smooth muscle ; Rat (Sprague-Dawley)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The histochemical distribution of hyaluronan (hyaluronic acid, HYA) was analysed in various types of muscles in the rat by use of a hyaluronan-binding protein (HABP) and the avidin-biotin/peroxidase complex staining procedure. Microwave-aided fixation was used to retain the extracellular location of the glycosaminoglycan. In skeletal muscles, HYA was detected in the connective tissue sheath surrounding the muscles (epimysium), in the septa subdividing the muscle fibre bundles (perimysium) and in the connective tissue surrounding each muscle fibre (endomysium). HYA was heterogeneously distributed in all striated muscles. In skeletal muscles with small fibre dimensions (e.g., the lateral rectus muscle of the eye and the middle ear muscles), HYA was predominantly accumulated around the individual muscle fibres. Perivascular and perineural connective tissue formations were distinctly HYA-positive. In cardiac muscles, HYA was randomly distributed around the branching and interconnecting muscle fibres. In comparison, smooth muscle tissue was devoid of HYA.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Journal of comparative physiology 156 (1986), S. 683-689 
    ISSN: 1432-136X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Ventilation frequency, volume, oxygen uptake, and oxygen transport by the blood have been studied in unrestrained octopus,Octopus vulgaris before, during and after recovery from 20 min of enforced activity. Exercise increased oxygen consumption 2.8 fold. The percentage utilisation of oxygen from the branchial water is maintained or increased at around 35% during activity and the calculated ventilation volume increases by 3 times. Prior to exercise the hemocyanin in arterial blood is 98% saturated and there is 83% utilisation of the oxygen in the blood. During activity there is remarkably little change in blood parameters so that the hemocyanin in the arterial blood remains at 96% saturation and oxygen utilisation is 90%. Cardiac output was calculated to have risen 2.5 fold during activity. As theP O 2 gradients across the gill do not change significantly during exercise the major adaptation which can account for an increase in oxygen consumption must be a 3 fold increase in the transfer factor. At rest 22% of the total CO2 present in the blood is excreted during its passage through the gills and this rises to 32% during activity. There is no accumulation of CO2 and only a slight acidification of the blood during activity. A significant respiratory and metabolic acidosis is avoided and the hemocyanin continues to function normally.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Journal of comparative physiology 148 (1982), S. 35-40 
    ISSN: 1432-136X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary 1. The respiration ofOctopus vulgaris was investigated, particular attention being given to the role of the blood in the uptake and transport of oxygen. Measurements were made on free moving animals. Oxygen consumption was recorded and blood sampled with indwelling cannulae in pre and post branchial (aortic) vessels. 2. In normoxia the mean values for circulating bloodP O 2 are 78.1±2.9 mmHg for arterial and 30.0±3.2 mmHg for venous blood. The hemocyanin in arterial blood is 98% saturated and 14% saturated in venous blood. There is a 0.11 pH unit decrease between arterial and venous blood. 3. The in vitro Bohr coefficient has a value of −1.58 Δlog10 P 50/Δ pH. 4. In hypoxia the oxygen consumption declined markedly below an ambientP O 2 of 90 mmHg. 5. Hypoxia was accompanied by a decline in aorticP O 2 but a near mainstenance of arterial hemocyanin saturation so that the arterial to venous difference declined by only 17% between normoxia and the most acute hypoxia. A marked increase in hemocyanin oxygen affinity occurred with a rise in blood pH. The large Bohr factor of the blood may be a major adaptation to hypoxic conditions, while bradycardia and modulations of stroke volume may play only a small part.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Journal of comparative physiology 170 (2000), S. 261-268 
    ISSN: 1432-136X
    Keywords: Key words Nautilus ; Hypometabolism Hypoxia ; Blood gases ; pH
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Specimens of Nautilus pompilius were trapped at depths of 225–300 m off the sunken barrier reef south-east of Port Moresby, Papua New Guinea. Animals transported to the Motupore Island laboratory were acclimated to normal habitat temperatures of 18 °C and then cannulated for arterial and venous blood sampling. When animals were forced to undergo a period of progressive hypoxia eventually to encounter ambient partial pressure of oxygen (PO2) levels of ∼10 mmHg (and corresponding arterial PO2's of ∼5 mmHg), they responded by lowering their aerobic metabolic rates to 5–10% of those seen in resting normoxic animals. Coincident with this profound metabolic suppression was an overall decrease in activity, with brief periods of jet propulsion punctuating long periods of rest. Below ambient PO2 levels of 30–40 mmHg, ventilatory movements became highly periodic and at the lowest PO2 levels encountered, ventilation occasionally ceased altogether. Cardiac output estimated by the Fick equation decreased during progressive hypoxia by as much as 75–80%, and in the deepest hypometabolic states heart rates slowed to one to two cycles of very low amplitude per minute. By the end of 500 min exposure to ambient PO2 levels of 10 mmHg or less, the anaerobic end products octopine and succinate had increased significantly in adductor muscle and heart, respectively. Increased concentrations of octopine in adductor muscle apparently contributed to a small intracellular acidosis and to the development of a combined respiratory and metabolic acidosis in the extracellular compartment. On the other hand, increases in succinate in heart muscle occurred in the absence of any change in cardiac pHi. Taken together, we estimate that these anaerobic end products would make up less than 2% of the energy deficit arising from the decrease in aerobic metabolism. Thus, metabolic suppression is combined with a massive downregulation of systemic O2 delivery to match metabolic supply to demand.
    Type of Medium: Electronic Resource
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  • 7
    Publication Date: 1991-02-01
    Print ISSN: 0302-766X
    Electronic ISSN: 1432-0878
    Topics: Biology , Medicine
    Published by Springer
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  • 8
    Publication Date: 2022-05-25
    Description: © The Author(s), 2017. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Animal Cognition 20 (2017): 1067–1079, doi:10.1007/s10071-017-1123-5.
    Description: Most mammals can accomplish acoustic recognition of other individuals by means of “voice cues,” whereby characteristics of the vocal tract render vocalizations of an individual uniquely identifiable. However, sound production in dolphins takes place in gas-filled nasal sacs that are affected by pressure changes, potentially resulting in a lack of reliable voice cues. It is well known that bottlenose dolphins learn to produce individually distinctive signature whistles for individual recognition, but it is not known whether they may also use voice cues. To investigate this question, we played back non-signature whistles to wild dolphins during brief capture-release events in Sarasota Bay, Florida. We hypothesized that non-signature whistles, which have varied contours that can be shared among individuals, would be recognizable to dolphins only if they contained voice cues. Following established methodology used in two previous sets of playback experiments, we found that dolphins did not respond differentially to non-signature whistles of close relatives versus known unrelated individuals. In contrast, our previous studies showed that in an identical context, dolphins reacted strongly to hearing the signature whistle or even a synthetic version of the signature whistle of a close relative. Thus, we conclude that dolphins likely do not use voice cues to identify individuals. The low reliability of voice cues and the need for individual recognition were likely strong selective forces in the evolution of vocal learning in dolphins.
    Description: Fieldwork for this study was funded by Harbor Branch Oceanographic Institution, Grossman Family Foundation, Dolphin Quest, Inc., NOAA Fisheries, Disney, the Office of Naval Research, Morris Animal Foundations Betty White Wildlife Rapid Response Fund, the Batchelor Foundation, and the Joint Industry Program.
    Keywords: Dolphin ; Playback experiment ; Non-signature whistle ; Voice cues ; Individual recognition
    Repository Name: Woods Hole Open Access Server
    Type: Article
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  • 9
    ISSN: 1432-041X
    Keywords: Histones ; Sea urchins ; Regulation of gene expression ; Maternal messenger RNA
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The ability to specifically delete the store of maternal α-subtype histone mRNAs stored in the egg pronucleus has allowed us to examine the role of this major fraction of the maternal mRNA in the early development of the sea urchinStrongylocentrotus purpuratus. The egg nucleus was removed by centrifugation, and the resulting enucleate half eggs were fertilized. These haploid andromerogones lacked any stored α-subtype histone mRNAs. However, when grown in parallel with control embryos, they showed identical cleavage cycles, cell numbers, and patterns of cell differentiation. Measurements of the amount of α-histone mRNA in these andromerogones showed that there was no premature synthesis of α-histone mRNAs to compensate for the deleted maternal pool. Instead embryonic synthesis was normal in timing of initiation and duration. the ability of these embryos to develop into highly differentiated larvae without their maternal α-subtype histone mRNA pool suggests that this pool is not a critical component of early development per se. This suggestion is strengthened by the observation that the primitive sea urchinEucidaris tribuloides naturally lacks this maternal histone mRNA store. Evolutionary implications are discussed.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Development genes and evolution 202 (1993), S. 112-122 
    ISSN: 1432-041X
    Keywords: Axon guidance ; Drosophila ; Enhancer trap ; Kinesin-lacZ ; Neural development
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary We have analyzed the development of neuronal projections inDrosophila by fusing the gene encodingDrosophila kinesin, a microtubule-associated motor protein, toEscherichia coli lacZ, and employing the resulting chimeric protein as a reporter molecule for labelling cells by the “enhancer-trap” method. Expression of kinesin-β-galactosidase in neurons has afforded a detailed view of the morphologies and projections of neurons. The images of cells provided by this method will facilitate anatomical and genetic investigations of theDrosophila nervous system as well as other cell types.
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