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  • 1
    Electronic Resource
    Electronic Resource
    Valine uptake by the scleractinian coral Galaxea fascicularis: characterization and effect of light and nutritional status (1993)
    Springer
    Journal of comparative physiology 163 (1993), S. 355-362 
    Details
    ISSN: 1432-136X
    Keywords: Amino acid uptake ; Light ; Feeding ; Coral, Galaxea fascicularis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The characteristics of valine uptake by isolated microcolonies of Galaxea fascicularis (Linnaeus 1758) were studied under various conditions including light, dark and feeding. The results demonstrated the presence of: (1) a linear component which might represent either a diffusional transport or a low-affinity carrier-mediated transport (apparent carrier affinity 〉250 μmol·l−1), and (2) a high-affinity active carrier-mediated transport (apparent carrier affinity about 5 μmol·l-1). The latter is mediated by two different systems: (i) a Na+-dependent carrier, stimulated by light and operative in both fed and unfed polyps, and (ii) a Na+-independent carrier, light insensitive and present only in unfed polyps. Competition experiments with other amino acids show that the Na+-dependent carrier is highly specific for neutral amino acids, as indicated by the high inhibition constants of basic and acidic amino acids. Our results suggest that the energy supplied by zooxanthellae photosynthates is necessary for the process of amino acid uptake, and that the Na+-dependent carrier responsible for valine uptake by G. fascicularis is similar to the B0,+ system.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00265638
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Fatty acids of the scleractinian coral Galaxea fascicularis: effect of light and feeding (1995)
    Springer
    Journal of comparative physiology 165 (1995), S. 183-192 
    Details
    ISSN: 1432-136X
    Keywords: Zooxanthellae ; Fatty acids ; Light ; Feeding ; Coral, Galaxea
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract In order to investigate nutritional interactions in the symbiotic scleractinian coral-zooxanthella association, fatty acids of the coral Galaxea fascicularis were analysed in two groups of cultured microcolonies. The first group was fed with Artemia sp., while the second group was starved. After an initial 1-month period during which both groups were subjected to the same “normal” light conditions (constant irradiance of 125 μE·cm-2·s-1 and 14:10 h light:dark), a light cap was used to cover the aquarium and keep all the microcolonies in permanent darkness for 20 days. During the light phase of the experiment it was shown that the nutritional status lead to large variations in the percentage of saturated, mono-unsaturated and polyunsaturated fatty acids. Palmitic acid (C16:0) was the most abundant fatty acid in both groups. Important differences between fed and starved microcolonies occurred during the dark phase of the experiment. In the fed group the dark phase was characterized by a significant increase in polyunsaturated fatty acids. Particularly arachidonic acid (C20:4 n-6) became the most important fatty acid followed by docosatrienoic acid (C22:3 n-3). A slight increase in these two fatty acids was also found in the starved group but the bulk of polyunsaturated fatty acids was significantly decreased. In this group, palmitic acid remained the most important fatty acid while an increased concentration of cis-vaccenic acid (C18:1 n-7) was found at the end of the experiment. The increased concentration of cis-vaccenic acid might indicate that bacteria serve as a source of energy. While the number of zooxanthellae per milligram of protein and the chlorophyll a to protein ratio strongly decreased in the starved microcolonies immediately after the beginning of the dark period, the decrease in fed microcolonies was delayed for about 10 days. Furthermore, after 20 days of dark incubation the chlorophyll a to protein ratio was the same as measured at the beginning of the dark period. This suggests that in the dark the metabolic requirements of the zooxanthellae are in part met from the animal host through a heterotrophic mode of nutrition.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00260809
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    Paper (German National Licenses)
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