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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Helgoland marine research 24 (1973), S. 284-291 
    ISSN: 1438-3888
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Summary 1. The effect of varying light intensities on the rates of calcification and CO2 fixation in the coralMontastrea annularis is described. 2. High light intensities, above the saturation point of symbiont photosynthesis, are shown to inhibit the rate of calcification in both shallow and deep specimens. 3. Light enhanced calcification in reef-building corals appears to be an energy-requiring process involving the active transport of calcium and carbonate ions, and the translocation of symbiont photosynthate.
    Notes: Kurzfassung Das Ausmaß der Verkalkung und photosynthetischen Kohlenstoffixierung wurde bei Individuen vonMontastrea annularis in verschiedenen Rifftiefen und unter spezifischen Lichtbedingungen mittels der Radioisotope45Ca und14C bestimmt. Die Lichtintensität beeinflußt über die photosynthetische Tätigkeit der symbiotischen Algen vor allem die Geschwindigkeit der Verkalkung und zudem sehr wahrscheinlich die gesamte Wuchsform der Kolonie. Im allgemeinen fördern zunehmende Lichtintensitäten den Prozeß der Verkalkung, wenngleich von einer Sättigungsgrenze an dieser Vorgang eine rückläufige Tendenz aufweist. Eine derartige Beziehung konnte parallel hierzu auch für die Intensität der C-Fixierung und photosynthetischen O2-Produktion festgestellt werden. Diese in situ gewonnenen Ergebnisse wurden durch Laboruntersuchungen bestätigt.
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Cellular and molecular life sciences 28 (1972), S. 873-874 
    ISSN: 1420-9071
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Zusammenfassung Mit Hilfe der Polarographie wird die Kinetik der Solvolyse vonp-Methoxy-isopropalakohol bestimmt.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Amino acids 7 (1994), S. 267-278 
    ISSN: 1438-2199
    Keywords: Amino acids ; Protein synthesis ; tRNA charging ; Amino acid metabolism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Specific radioactivity in three amino acid compartments was examined in broiler chicks following a flooding dose of leucine or phenylalanine. In general, specific radioactivity of leucine and phenylalanine in deproteinated plasma (SAe) and tissue (SAi) compartments, exceeded that in acylated-tRNA (SAt). In most tissues, SAe and SAi rapidly reached a similar peak level by 5 min followed by a slow decline for the next 30 minutes. Many tissues (eg. GI tract, liver, skin, and thigh) failed to maintain equilibrium between SAe and SAi over time. More metabolically active tissues, such as GI and liver had the greatest differences between these compartments. The difference between SAe and SAi for both leucine and phenylalanine were due to SAi decreasing faster than SAe, indicating dilution with unlabelled amino acids from proteolysis. Plasma and tissue specific radioactivity overestimated tRNA specific radioactivity by as much as 5 and 2.8 fold using leucine or 2.7 and 1.4 fold using phenylalanine, respectively. These data suggest that intracellular compartmentation of protein metabolism and the coupling of protein degradation and synthesis occur, in vivo.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Four colonies of Acropora formosa were incubate with Na2 14CO3 for separate 2 h periods within a 24 h period, and then returned to the reef from which they were collected. Terminal branches were collected at intervals over the following 5 d and analysed for radioactivity associated with the skeleton and certain organic pools. Colonies incubated at night showed little or no loss of fixed radioactivity during the 5 d on the reef. However, 50–60% of photosynthetically-fixed 14C was lost from the terminal branches during the first 40 h on the reef. This loss of radioactivity probably resulted from release of mucus and dissolved organic carbon from the coral tissues. Most of the loss of photosynthetically-fixed 14C was due to decrease in the radioactivity of lipids (80% of the total 14C loss) and methanol-water soluble compounds. Determination of any sequencing in metabolic compartments was made difficult by the rapidity with which 14C dissappeared from most of the metabolic pools measured. 14C was incorporated into the skeleton throughout the 5 d on the reef, although the rate of incorporation was very low in colonies which had been incubated with Na2 14CO3 at night.
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  • 5
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Large variations in skeletal microarchitecture, and in the carbon and oxygen isotopic composition of the skeleton, exist within single calices and over the surfaces of single colonies of various species of West Indian (Jamaican) scleractinian reef corals. Rapidly extending parts of individual colonies are depleted in both C13 and O18 regardless of the abundance of zooxanthellae in the overlying tissues. We suggest that this relationship is due to active translocation of organic compounds to sites of rapid calcification. Considerable variation in isotopic composition is found in skeletons of different specimens of the same species even when the skeletons are sampled in a consistent manner, come from the same locality and depth, and have a comparable growth history. The isotopic composition of the scleractinian skeleton is vastly more complex than has heretofore been realized.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Pieces of branch from the staghorn coral Acropora acuminata were incubated with 45CaCl2 and NaH14CO3 under identical conditions in the light or in the dark. Specimens were then processed in different ways. All specimens were placed in N KOH to digest tissues. Some were placed in KOH immediately after incubation; others were placed in KOH after 2 h washing, or after 2 h extraction with methanol-chloroformwater. Specimens were washed in running fresh water or running seawater; some were killed in liquid N2 before washing. Radioactivity associated with skeleton and tissues was determined. The method of processing profoundly affected the results. In dark incubations, there was up to a four-fold difference in apparent skeletal incorporation of 45Ca++ between average values obtained for the different treatments. For 14C incorporation, there was a difference of up to 2.5 times. In light incubations, skeletal incorporation of both radioisotopes showed a two-fold difference between high and low average values obtained for the different treatments.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Coral reefs 1 (1982), S. 53-57 
    ISSN: 1432-0975
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Summary Under standard experimental conditions, sample groups of Acropora acuminata gave calcification results having a coefficient of variation approaching 50%. Because of this, the resolution of radioisotope measurements approaches the magnitude of the effect of light on calcification rate. Differences in calcification rate between samples appear to be caused by short-term variations in calcification rate of samples, rather than size differences between samples. The coefficient of variation associated with results can be decreased by relatively straightforward modifications to the standard technique.
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Coral reefs 18 (1999), S. 213-218 
    ISSN: 1432-0975
    Keywords: Key words Sedimentation ; Porites ; Skeletal density banding ; Growth characteristics ; Tissue thickness
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract  The construction in 1988 of an open-cut gold mine and ore-processing facility at Misima Island, Papua New Guinea, resulted in disturbance of the adjacent fringing coral reef, mostly because of large increases in sedimentation. This provided an opportunity to examine whether growth characteristics of the major reef-building coral, Porites, changed in response to this sudden and sustained increase in sedimentation. Annual variation in skeletal density was measured in 93 colonies variously affected by sedimentation. The colonies provided data for average annual density, annual extension and annual calcification covering the periods 5 y before and 5 y after mining operations began. The average depth of skeleton occupied by tissue (tissue layer thickness) was also measured for most colonies. There was high mortality of Porites in regions strongly affected by increased sedimentation. In colonies that survived, density, extension and calcification tended to be less (in some cases significantly) in the period after mining operations began compared with pre-construction levels. However, these decreases were not linked with proximity to the mine site and probably reflect a regional-scale response of Porites growth to some other environmental change. This suggests that periods of high sedimentation may not be recorded by the growth characteristics of massive Porites. Average growth characteristics of surviving Porites from Misima Island were similar to those from inshore reefs of the northern Great Barrier Reef (GBR). Tissue layer thickness in Porites from the control areas at Misima Island were also similar to colonies from the northern inshore GBR reefs. However, tissue layer thickness significantly decreased with increased proximity to the mine site at Misima Island.
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Coral reefs 9 (1990), S. 11-23 
    ISSN: 1432-0975
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract A method is described for the measurement of the density of calcium carbonate materials from the attenuation of a narrow, collimated beam of gamma photons. For the measurement of density for slices, approximately 0.5 to 1.0 cm thick, from the skeletons of reef building corals, the optimum beam energy is 30–34 keV; and measurement is practical from approximately 22 to 100 keV. The potential utilities of five commercially available isotopic sources (109Cd,125I,253Gd,210Pb and241Am) are evaluated. Methods and results are presented for gamma densitometry using210Pb and241Am. The210Pb point source had its principal gamma emission at 46.5 keV. Bremsstrahlung and high energy (800 keV) gamma emissions associated with the210Pb decay grand-daughter were detected, and procedures were developed to accommodate the contribution of these emissions to the overall count rate. The attenuation of count rate by aluminium and aragonite absorbers closely followed simple theoretical considerations provided that narrow energy window settings were used at the radiation monitor. These theoretical considerations take account of the density of the material absorbing the radiation, and hence the density could be determined from the attenuation of the gamma beam. Increased accuracy was achieved by the use of241Am and high speed counting equipment.241Am has its principal gamma emission at 59.6 keV. The attenuation of this gamma beam follows simple theoretical considerations for targets with mass thicknesses from 0 to 6 g cm-2. Aragonite from the shell of a giant clam was found to have slightly different properties in the absorption of gamma photons to aragonite from a coral skeleton. The differences were small but statistically significant.
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Current genetics 10 (1986), S. 767-775 
    ISSN: 1432-0983
    Keywords: Aspergillus ; Transformation ; Recombinant plasmids ; Autonomously replicating sequences
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary A pyrG − Aspergillus strain was transformed with plasmid pDJB-1, derived from pBR325 by insertion of the Neurospora crassa pyr4 gene (orotidine 5′-phosphate carboxylase), giving mitotically unstable transformants. Aspergillus DNA which acted as an “autonomously replicating sequence” (ARS) in yeast was inserted into pDJB-1 and the resulting construct, pDJB12.1, gave mitotically stable transformants when introduced into Aspergillus. Transformants obtained with pDJB-1 and pDJB12.1 gave few pyr − progeny in crosses to a pyrG + strain. Southern hybridisation analysis of pyr + transformants obtained with pDJB-1 revealed restriction fragments expected for integrated plasmid but transformants obtained with pDJB12-1 showed only bands derived from free plasmid. pDJB-1 and derivatives of pDJB12.1 could be recovered from transformants. These derivatives could not be explained by straightforward excision of integrated pDJB12.1 sequences but could result from recombination between plasmid molecules. Hybridisation of undigested transformant DNAs showed that the transforming DNA was present in a high molecular weight form. These results suggest: (1) pDJB12.1 derivatives and possibly pDJB-1 can replicate autonomously in Aspergillus; (2) A. nidulans DNA acting as an ARS in yeast enhances replication and/or segregation of transforming plasmids in Aspergillus; and (3) recombinant plasmids may undergo rearrangements when introduced into Aspergillus.
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