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  • 1
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Branching heads of symbiotic corals were pulse labeled with either 14C-acetate or 14C-bicarbonate for 1.33 h and the distribution and loss of label was then followed for 16d. The patterns of incorporation and washout were similar for both tracers. Non-solvent-extractable radioactivity (1/3 of the total) was divided into a CaCO3 and an organic fraction, both of which exhibited small if any decrease in radioactivity over 16d. In contrast, total solvent extractable (lipid) radioactivity (2/3 of the total) decreased during the washout period with the first half-life for bicarbonate at 2 d, the second at 4 d and the third could not be measured because of the persistence of a constant amount of radioactivity (18% of Day 1 value) from Day 8 to 16. Of the total retained activity, the zooxanthellae fraction contained between 8–18% from Day 1 to 5. The percentage of total animal (host) radioactivity in lipids rose from 35–40% at 0 time after tracer exposure to 70–90% at 60 min. The majority of 14C fixed into lipids was recovered in the fatty acyl moieties and not in the glycerol moiety as had been previously reported a number of times. These studies suggest that photosynthetically fixed carbon is immediately synthesized into lipid, which is translocated to the host. Analyses of the fatty acid compositions of triacylglycerols (TG) and wax esters (WE) of 40 species of coral from a small patch reef were made. In aposymbiotic species the absence of zooxanthellae appeared to be correlated with higher levels of total lipid, lower percentages of saturated fatty acids and lower TG/WE ratios than in species with symbionts.
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  • 2
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Corals in an in situ respirometer exposed to suspended peat during the day greatly decreased net oxygen production, probably due to a reduction of intensity and spectral quality of light reaching the symbiotic zooxanthellae. Net production returned to pre-exposure levels after the chambers were cleared; the corals showed no behavioral effects. In contrast, after exposure during the night, corals displayed clearing behavior (such as extreme distension of the coenosarc and trapping of peat particles in thick clumps of mucus) and an increase in respiration rate comparable to the decrease in net production observed during the daytime exposure. The following morning, net production values were significantly lower than pre-exposure production values although ambient light intensity was slightly higher. This decrease in production as well as a 22% reduction of chlorophyll content in the coral tissue indicated loss of zooxanthellae from the stressed corals. Long-term exposure to such a stress could reduce coral growth rates and substantially alter coral reef communities.
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Journal of fusion energy 9 (1990), S. 273-273 
    ISSN: 1572-9591
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1572-9591
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract We have carried out a series of experiments to test the recently claimed observations of cold fusion. In a first experiment, we used an electrochemical cell with a Pd wire cathode. Neutrons were detected by the1H(n,γ) photons from surrounding water and paraffin. In a second experiment, two vacuum-cast Pd disks were the cathodes in “twin” cells, one with H2O, and the other with D2O. The two cells were shuttled every 24 hours between similar detector setups, equipped with neutron, γ- and x-ray detectors. A third experiment was designed to measure production of charged particles, using an Si surface barrier detector viewing the back of a 76-μm thick Pd foil cathode. No statistically-significant evidence of nuclear fusion has been obtained in any of these experiments, either in steady-state operation or in transient response to a variety of perturbations. Upper bounds on the rate of various postulated fusion processes were set including 〈2×10−23 neutrons (dd pair)−1 s−1 for the d(d,n)3He reaction and 〈6×10−25 protons (dd pair)−1 s−1 for the d(d,p)3H reaction (2σ level). Chemical analysis of our electrolytes revealed no anomalous increase in3H concentrations. (PACS numbers: 82.45.+z,29.30.-h,29.70.-e,25.45.-z).
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  • 5
    ISSN: 1432-0630
    Keywords: 74.60 ; 74.70
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract The temperature and magnetic-field dependences of the remanent magnetization have been determined from far-field measurements for thallium ceramic samples. The current flow that gives rise to the observed magnetization is intragranular. The results are consistent with flux-creep-controlled transport with a distance between pinning centers of ∼- 1/2/μm. Using near-field measurements, the superconducting properties are found to be heterogeneous on a scale of ≫ 1 mm. Magnetic domains have been induced by pplying spatial variation in the applied field.
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Cellular and molecular life sciences 26 (1970), S. 1150-1151 
    ISSN: 1420-9071
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Résumé Des moitiés d'hypophyse incubées dans du plasma de la tige hypophysaire sécrétent moins de prolactine que les moitiés complémentaires incubées dans du plasma de sang périphérique. Les glandes incubées dans du plasma de la tige hypophysaire de rats traités à la dopamine sécrètent moins de prolactine que celles incubées dans le plasma des rats témoins. L'activité inhibitrice de la prolactine dans le plasma de la tige hypophysaire peut Être le résultat d'un facteur particulier, et la sécrétion de ce facteur serait gouvernée par un mécanisme «dopaminergique».
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Archives of microbiology 96 (1974), S. 1-16 
    ISSN: 1432-072X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Prosthecae were sheared from cells ofAsticcacaulis biprosthecum with a Sorvall omnimixer and purified by centrifugation. Removal of prosthecae resulted in no loss in viability. Purified prosthecae contain protein, carbohydrates and lipids. Certain enzymes that are present in the main body of the cell are also present in prosthecae: malic dehydrogenase (E.C. 1.1.1.37), alkaline phosphatase (E. C. 3.1.3.1), succinic dehydrogenase (E.C. 1.3.99.1), cytochromec reductase (E.C. 1.6.2.a), and cytochromes. Other enzymes present in whole cells are not in prosthecae: isocitric dehydrogenase (E.C. 1.1.1.41), NADH oxidase (E.C. 1.6.99.3), glucose-6-phosphate dehydrogenase (E.C. 1.1.1.49), and lactic dehydrogenase (E.C. 1.1.2.3). Swarmer cells (non-prosthecate) were purified by allowing prosthecate cells to attach to cheesecloth in the growth medium. Envelopes prepared from prosthecae were compared with envelope from swarmer cells. The two envelope fractions differed in the disc-gel electrophoretic patterns of proteins solubilized from them.
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Marine biology 100 (1989), S. 185-193 
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The pattern of resource partitioning vs depth by corals collected in February 1983 from Jamaica and the Red Sea was determined from their stable carbon isotope composition. Observations were made on isolated zooxanthellae and corresponding algae-free animal tissue from eight species at four depths over a 50 m bathymetric range. Zooxanthellae δ13C was high in shallow water and became lower as depth increased. This trend correlated significantly with the anual integrated photosynthetic rate. The trend is interpreted according to a “depletion-diffusion” hypothesis; in shallow water, at high rates of photosynthesis, metabolic CO2 is nearly depleted and the supply of CO2 from seawater bicarbonate is limited by diffusion. Since most of the available CO2 is fixed, isotope fractionation is minimal. In deeper water, at lower rates of photosynthesis, metabolic CO2 is ample, and isotope fractionation is greater. Animal tissue δ13C was slightly lower than corresponding zooxanthellae values in shallow water. As depth increased the difference between zooxanthellae and animal tissue δ13C increased and the latter approached the δ13C of oceanic particulate organic carbon. These data suggest that carbon is translocated at all depths and that deep-water corals draw significantly on allocthonous sources of carbon.
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Marine biology 75 (1983), S. 113-116 
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The effects of inorganic carbon concentrations on photosynthetic oxygen evolution of isolated zooxanthellae and coral tips from the hermatypic coral Seriatopora hystrix were measured in the laboratory using an oxygen electrode. Whole coral colonies of Stylophora pistillata were examined in situ, using a bioassay respirometer. Inorganic carbon concentrations above 2.3 mM, the ambient concentration of reef water, generally did not stimulate photosynthesis. These results indicate that inorganic carbon is not limiting to coral photosynthesis and that respiratory carbon dioxide production by the coral host probably has little effect on the photosynthetic rates of its symbiotic zooxanthellae.
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  • 10
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The chlorophyll specific absorption coefficient ( $$\bar k$$ c) was measured for zooxanthellae from six hermatypic coral species obtained, where possible, from four depths (1, 10, 30, 50 m) on reef sites near Discovery Bay, Jamaica in February and March 1983. Measurements of photosynthetic rates versus irradiance, as well as cellular and areal chlorophyll a, were also performed on these colonies or sister colonies. Together the data were used to compare minimum quantum requirements (1/Φ m) among species and depths and to assess the importance of light utilization to the growth and depth distribution of these corals. Our data suggest that, although $$\bar k$$ c was found to decrease with depth, interspecific differences in $$\bar k$$ c do not occur for zooxanthellae from the corals investigated. Minimum quantum requirements (1/Φ m) decreased significantly with depth, thereby reflecting an increase in photosynthetic light utilization efficiency with decreasing irradiance. Interspecific differences in 1/Φ m determinations were suggested but not statistically conclusive. We conclude that interspecific differences in gross photosynthesis, and perhaps growth and depth distribution, are primarily attributable to differences in the light utilization capacity of the whole coral, as reflected by the product of $$\bar k$$ c ′ and chlorophyll per unit surface area, and in-situ quantum efficiencies.
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