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  • 1
    Digitale Medien
    Digitale Medien
    Oxford, UK : Blackwell Publishing Ltd
    Plant, cell & environment 13 (1990), S. 0 
    ISSN: 1365-3040
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie
    Notizen: Abstract. 45Ca and 109Cd uptake were followed in Criscosphaera elongata Prymnesiophyceae. In both cases, after a rapid increase for the first 5 min, the incorporation rate slowed during the hour of observation. Verapamil, a blocker of voltage-dependent slow calcium channels, inhibited 45Ca uptake except during the first rapid phase when adsorption should predominate. Cadmium also decreased 45Ca labelling, suggesting that the two metals are antagonistic. However, verapamil was shown to augment 109Cd incorporation, contrary to what occurs in animals cells; this effect is detectable in continuous labelling as well as in pulse experiments. The data support the presence of calcium channels in the alga and suggest several processes in Cd accumulation: adsorption on peripheral envelopes and diffusion of uncharged Cd.
    Materialart: Digitale Medien
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    Amsterdam : Elsevier
    Experimental Cell Research 185 (1989), S. 407-418 
    ISSN: 0014-4827
    Quelle: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Thema: Biologie , Medizin
    Materialart: Digitale Medien
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 3
    ISSN: 0014-4827
    Quelle: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Thema: Biologie , Medizin
    Materialart: Digitale Medien
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 4
    Digitale Medien
    Digitale Medien
    Amsterdam : Elsevier
    Developmental Biology 118 (1986), S. 19-27 
    ISSN: 0012-1606
    Quelle: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Thema: Biologie
    Materialart: Digitale Medien
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 5
    Digitale Medien
    Digitale Medien
    Amsterdam : Elsevier
    Biochimica et Biophysica Acta (BBA)/Molecular Cell Research 1012 (1989), S. 219-226 
    ISSN: 0167-4889
    Schlagwort(e): (Sea urchin egg) ; Calcium ion ; Cell death ; Mercury chloride ; Mitochondrion ; Toxicology
    Quelle: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Thema: Biologie , Chemie und Pharmazie , Medizin , Physik
    Materialart: Digitale Medien
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 6
    Digitale Medien
    Digitale Medien
    Amsterdam : Elsevier
    Aquatic Toxicology 26 (1993), S. 171-184 
    ISSN: 0166-445X
    Schlagwort(e): Ca^2^+-induced cell death ; Fertilization ; HgCl"2 ; Intracellular pH ; Na^+/H^+ exchange ; Sea urchin egg
    Quelle: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Thema: Biologie
    Materialart: Digitale Medien
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 7
    Digitale Medien
    Digitale Medien
    Amsterdam : Elsevier
    Biochimica et Biophysica Acta (BBA)/Biomembranes 772 (1984), S. 337-346 
    ISSN: 0005-2736
    Schlagwort(e): (Sea urchin egg) ; Fertilization ; Na^+ dependence ; Valine transport
    Quelle: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Thema: Biologie , Chemie und Pharmazie , Medizin , Physik
    Materialart: Digitale Medien
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 8
    Digitale Medien
    Digitale Medien
    Springer
    Marine biology 117 (1993), S. 119-128 
    ISSN: 1432-1793
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The carbonate skeleton of the gorgonian coral Corallium rubrum (L.) is composed of both a skeletal axis and numerous sclerites scattered in the mesoglea. Studies carried out on these skeletal elements and their associated tisues using microscopy and X-ray microanalysis, suggest a close relationship between the process of sclerite formation and skeletogenesis. The skeleton is surrounded by an axial epithelium composed of a single cell type. These cells associate intimately with mesogleal sclerites and scleroblasts, incorporating them into a nascent skeleton at the branch tip. Subsequent (sub-apical) growth appears to occur solely through the agency of the axis epithelial cells that serve to physically separate mesogleal sclerites and scleroblasts from contact with the axis. The epithelium is associated with the production of layered calcite crystals and irregular protuberances that constitute the mature, calcareous skeleton. Free sclerites in the mesoglea appear to be the product of multiple cells that are cytologically indistinguishable from those in the axis epithelium. Like the axis, sclerites are produced as layers of calcite crystals with irregular protuberances. The protuberances differ only slightly from those of the axis, and the skeleton is mineralogically indistinguishable from the sclerites. Thus, the skeleton of red coral is not primarily the product of fused sclerites. Instead, we suggest that the axis epithelium treats the incipient skeleton as if it were the core of a single sclerite, and conversely, that the mesogleal scleroblasts of C. rubrum constitute a fragmented axis epithelium.
    Materialart: Digitale Medien
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 9
    ISSN: 1432-1793
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract A sensitive experimental protocol using cloned corals (hereafter “microcolonies”) of the branching scleractinian coral Stylophora pistillata and 45Ca has been developed to enable reproducible measurements of physiological and biochemical mechanisms involved in calcium transport and compartmentalization during coral calcification. Cloned S. pistillata microcolonies were propagated in the laboratory from small fragments of parent colonies collected in 1990 in the Gulf of Aqaba, Jordan. Cloned microcolonies have several intrinsic properties that help to reduce unwanted biological variability: (1) same genotype; (2) similar sizes and shapes; and (3) absence of macroscopic boring organisms. Errors specifically associated with long-standing problems to do with isotopic exchange were further reduced by producing microcolonies with no skeletal surfaces exposed to the radioisotope-labelled incubation medium. The value of the technique resides principally in its superior ability to elucidate transportation pathways and processes and not in its ability to quantitatively estimate calcium deposition by corals in nature. We describe here a rapidly exchangeable calcium pool in which up to 90% of the radioactive label taken up during incubations is located. This pool (72.9±1.4 nmol Ca mg-1 protein) is presumably located within the coelenteric cavity as suggested by the following: (1) it has 4-min half-time saturation kinetics; (2) the accumulation of calcium is linearly correlated with the calcium concentration of sea-water; and (3) its insensitivity to metabolic and ion transport inhibitors indicate that membranes do not isolate this compartment. Washout of this large extracellular pool greatly improved estimates of calcium deposition as evidenced by 10 to 40% reduction in coefficients of variation when compared with previous 45Ca2+ methods described in the literature. Comparisons of calcification measurements simultaneously carried out using the alkalinity anomaly technique and the 45Ca protocol described here show that the correlation coefficient of both techniques is close to 1. Unlike previous reports, our 45Ca2+-derived measurements are slightly lower than those computed from the alkalinity depletion technique.
    Materialart: Digitale Medien
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 10
    Digitale Medien
    Digitale Medien
    Springer
    Marine biology 126 (1996), S. 43-53 
    ISSN: 1432-1793
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract In order to characterize the permeability of the oral epithelial layers in cnidarians, we investigated the kinetics of transport of labelled ions (45Ca,22Na,36Cl) and organic molecules (14C-inulin-carboxyl,14C-ala) through the oral tissue of two cnidarian species,Anemonia viridis (Forsskål, 1775) andHeliofungia actiniformis (Quoy and Gaimard, 1833) using the Ussing chamber method. In both species, unidirectional Ca, Na and Cl fluxes were the same in both directions (ectoderm towards endoderm and vice versa), the net flux being equal to zero. The insensitivity of these unidirectional transepithelial fluxes to metabolic inhibitor (1 mM sodium cyanide) and calcium channel inhibitor (100 μM verapamil) and their linear dependence on calcium concentration suggest that these fluxes are simple driven by diffusion via a paracellular pathway. The epithelial layers were not permeable to inulin. Low-molecular weight amino acids such as alanine did not cross the epithelia but were absorbed by the ectoderm. The permeability coefficients indicate that the oral epithelial layers are leaky. It is suggested that the coelenteric cavity represents a compartment in which the ionic pool can be entirely renewed by simple diffusion. This process seems efficient enough to meet all calcium requirements in scleractinian corals.
    Materialart: Digitale Medien
    Standort Signatur Einschränkungen Verfügbarkeit
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