ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Electronic Resource
    Electronic Resource
    Do correlations exist between chromatophore arrangement and photosynthetic activity in seaweeds? (1981)
    Springer
    Marine biology 62 (1981), S. 111-117 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In Dictyota dichotoma, as in many other plants, the chromatophores which at low intensities occupy the cell walls perpendicular to the light beam move to the side walls parallel to the light beam if exposed to high light intensities. The aim of this investigation was to find out whether or not the changes from low- to high-intensity arrangement and vice versa function as an active control mechanism to regulate photosynthetic activity in D. dichotoma under the respective light condition. Four different experimental approaches were made: (a) In white and blue light experiments the changes of the transmittance and of the rate of photosynthetic oxygen production in high- and low-intensity arrangement were compared. (b) The kinetics of the depression and recovery of the PS-rates, as well as of the transmittance changes, were determined during high- and low-intensity movement, respectively. (c) Transmittance and PS-rates of thalli under illumination with polarized and unpolarized light of the same intensity (1,000 1x) were compared. (d) PS-rates of thalli after darkening as well as after preirradiation with weak and strong red light, conditions under which the chromatophores occupy the same position in the cells, were measured. In all these experiments the photosynthetic activity was strongly influenced by pre-illumination, but was independent of the respective chromatophore arrangement. This finding was confirmed by experiments with two other algae: (1) In the brown alga Alaria esculenta which does not display light-induced chromatophore displacements and concomitant transmittance changes, pre-irradiation with high light intensities decreases the PS-rates. (2) In the green alga Ulva lactuca, which shows circadian chloroplast movements, the PS-rates depend on the pre-irradiation only, irrespective of the chloroplast position. Thus we may conclude that in these organisms the function of chromatophore displacements is not the regulation of photosynthetic activity. Other ecological functions are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00388172
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Circadian rhythms in the chromatophore movements of Dictyota dichotoma (1984)
    Springer
    Marine biology 81 (1984), S. 217-222 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In the brown alga Dictyota dichotoma Lamour the phaeoplasts move to the anticlinal walls (profile position) in strong light and to the periclinal walls (face position) in dim light. By these movements transmittance changes are caused. If the algae were grown in light:dark cycles of about natural daylengths, circadian oscillations of the amplitudes and the kinetics of these transmittance changes are initiated. The lengths of the free running periods vary between 24 and 29 h. In addition, light:dark grown thalli were transferred into continuous dim or strong light or darkness, in order to check whether or not the rhythms continued under these conditions. By taking photomicrographs of intact thalli and of isolated cortical cell layers, prepared by bisecting, it could be shown that the maxima and minima of circadian transmittance changes correspond well with the number of phaeoplasts at the periclinal cell walls. The ecological relevance of these phenomena is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00393215
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Occurrence and biological role of light-induced chromatophore displacements in seaweeds (1979)
    Springer
    Marine biology 51 (1979), S. 77-82 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The occurrence of light-induced chromatophore displacements and concomitant transmittance changes in marine algae was investigated by microscope and photometrically with an automated recording microphotometer system; 16 brown, 6 green and 20 red algae were studied. In most of the brown algae, both phaeoplast displacements and transmittance changes were found. In some red algae which are frequently exposed to direct sun light during emergence at low tide, light-induced transmittance changes were measured, but they could not unequivocally be correlated with changes in the position of rhodoplasts. Among green algae, only Ulva lactuca shows chloroplast displacements which, however, follow circadian rhythms and are consequently not light-induced in the strict sense. The dose-response curves of light-induced chromatophore displacements were measured in the following Fucus and Laminaria species: F. spiralis, F. vesiculosus, F. serratus, L. digitata, L. saccharina and L. hyperborea. While in Fucus species correlations between light-induced transmittance changes and zonation of the intertidal area seem to exist, no significant differences have been found in the Laminaria species. The physiological role and ecological importance of light-induced chromatophore displacements for seaweeds living in the intertidal belt are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00389033
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    Allelic diversity at the Mhc-DQA locus in cotton rats (Sigmodon hispidus) and a comparison of DQA sequences within the family Muridae (Mammalia: Rodentia) (1999)
    Springer
    Immunogenetics 49 (1999), S. 886-893 
    Details
    ISSN: 1432-1211
    Keywords: Key words Major histocompatibility complex ; DQA ; Sigmodon hispidus ; Muridae ; Allelic diversity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract  The cotton rat (Sigmodon hispidus) is a common murid rodent of the southern United States, Mexico, and Central America. Using single-stranded conformation polymorphism analysis and DNA sequencing techniques, 11 DQA exon 2 alleles were detected among 180 S. hispidus from Caddo County, Oklahoma, USA. The alleles represent a single locus exhibiting a high level of polymorphism. Nucleotide and amino acid distance values among DQA alleles of S. hispidus were higher than those within Mus musculus and species of Rattus. Although the distribution of polymorphic amino acid residues among alleles of S. hispidus was similiar to that of Mus and Rattus, some residues of the α-helix region were more variable in S. hispidus. Comparisons of nonsynonymous and synonymous substitutions indicated a trend toward higher numbers of nonsynonymous substitutions; however, this difference was not significant statistically among S. hispidus alleles. To examine evolution of DQA alleleswithin Muridae, we performed a phylogenetic analysis that included DQA alleles from S. hispidus, Peromyscus leucopus, M. musculus, R. norvegicus, and six Australian species of Rattus. Results depicted monophyly for each genus, and this concordance between species and gene trees represents a lack of evidence for trans-species persistence of alleles among these genera.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002510050569
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    Effects of calcium channel blockers on phototaxis and motility of Chlamydomonas reinhardtii (1986)
    Springer
    Archives of microbiology 144 (1986), S. 393-397 
    Details
    ISSN: 1432-072X
    Keywords: Chlamydomonas reinhardtii ; Phototaxis ; Motility ; Flagellates ; Flagellar movement ; Calcium ; Calcium channel blockers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The effects of the four calcium channel blockers flunarizine, verapamil, diltiazem and nimodipine on motility and phototaxis of Chlamydomonas reinhardtio have been tested with a fully automated and computerized population system. Flunarizine inhibits motility transiently by causing the detachement of the flagella which, however, are regenerated during some hours. Phototaxis is inhibited to the same extent, but this is simply the result of the decreased motility and, hence, a non-specific effect. Verapamil causes also a detachement of the flagella with following regeneration, but in addition motility and phototaxis are inhibited by this drug to different extents, indicating the involvement of calcium channels in both processes. Diltiazem and nimodipine inhibit phototaxis without impairing motility, indicating that both processes are regulated in different ways. If diltiazem and nimodipine are applied simultaneously, no additive inhibitory effect can be observed. However, the combination of both blockers with verapamil causes and additive inhibitory effect as if verapamil is applied alone. By increasing the external calcium concentration from 10-4 M to 10-3 M the optimum of positive phototaxis is shifted to higher fluence rates. This shifting occurs also in the presence of channel blockers, but the strength of the positive reaction is influenced. These results point to the involvement of calcium channels in both phototaxis and motility, but simultaneously demonstrate the different sensitivity of the two processes to these drugs.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00409890
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 6
    Electronic Resource
    Electronic Resource
    Chromatophorenanordnungen in emersen Thalli vonFucus vesiculosus unter verschiedenen Lichtbedingungen (1979)
    Springer
    Helgoland marine research 32 (1979), S. 228-238 
    Details
    ISSN: 1438-3888
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The effects of light and darkness on chromatophore arrangements inFucus vesiculosus thalli exposed to air with one side (half dry) or with both sides (dry) were investigated. Low-intensity arrangement, high-intensity arrangement and dark arrangement were induced in submerged thalli. Then the thalli were exposed to air while light conditions were either kept constant or were changed. Independently of the light conditions, in all thalli exposed to air the chromatophores arranged more or less in the inner area of the cells, in epidermal cells as well as in cortical cells. Thus the chromatophore arrangements observed in submerged thalli differ in some respect from those exposed to low-tide conditions. Based on these observations the physiological and ecological role of chromatophore displacements in seaweeds is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02189899
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 7
    Electronic Resource
    Electronic Resource
    Der Vorderflügel großer Heuschrecken als Luftkrafterzeuger (1981)
    Springer
    Journal of comparative physiology 142 (1981), S. 135-140 
    Details
    ISSN: 1432-1351
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The functional mechanics of the forewingtwisting ofLocusta migratoria L. is described and demonstrated by means of plastic models. The upstroke-supination (“Z-profile”) is produced by elastic and aerodynamic forces only. A tonic muscle, the muscle of the axillary 3, acts as upstroke-pronator, flattening the Z-profile. The three direct wing depressor muscles (basalar muscles, subalar muscle) pronate the wing during the downstroke. The basalar muscles initiate the wing-turning at the begin of downstroke by clicking the Z-profile into a reverse clap profile. The muscle of the axillary 3 decreases the downstroke-pronation, acting in this phase as a supinator. This muscle is therefore able to increase the aerodynamical angle of attack in both wingstroke phases. The functional significance of the muscles for the control of flight is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00605485
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 8
    Electronic Resource
    Electronic Resource
    Temperature dependence and response characteristics of the isolated wing hinge stretch receptor in the locust (1989)
    Springer
    Journal of comparative physiology 165 (1989), S. 247-252 
    Details
    ISSN: 1432-1351
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary 1. A preparation is described by which the wing hinge stretch receptor (SR) ofLocusta migratoria is mechanically isolated so that it can be subjected to stretch stimuli while avoiding interference with wing hinge mechanics. 2. Using this approach and sinusoidal stretches of different amplitudes the SR can be stimulated up to a definite saturation frequency. The discharge frequency at a given stretch and the saturation frequency both depend dramatically on ambient temperature. High instantaneous frequencies (up to 650 Hz, as found in flying locusts) were only obtained at a high temperature of 32 °C. 3. The instantaneous spike frequency of the SR in response to short stretches (within the time range of wing beat period) reflects exactly the amount of the stretch and not its rate of change. Thus, the SR is a receptor signalling the momentary position of the sclerites to which it is attached.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00619199
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 9
    Electronic Resource
    Electronic Resource
    Interpretation problems of intestinal iron absorption from isotopically labelled meat (1974)
    Springer
    Cellular and molecular life sciences 30 (1974), S. 43-44 
    Details
    ISSN: 1420-9071
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Zusammenfassung Die Untersuchung von Schweinefleisch, markiert mit59Fe in vivo, ergab unterschiedliche59Fe/Fe-Werte in den Fe-haltigen Fraktionen, so dass von der extern messbaren59Fe-Retention nicht direkt auf die resorbierbare Fe-Menge des Fleisches geschlossen werden kann.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01921586
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 10
    Electronic Resource
    Electronic Resource
    Radiometric estimation of the amount of solid gastrointestinal contents (1974)
    Springer
    Cellular and molecular life sciences 30 (1974), S. 1296-1298 
    Details
    ISSN: 1420-9071
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Zusammenfassung Durch Messung der pro Zeiteinheit aufgenommenen Trockensubstanzmenge, der Überführungskonstante des inerten Markers152Eu in den Kot und dessen Verzögerunszeit bis zur erstmaligen Exkretion liess sich bei zwölf 78 Wochen alten Bullen die Trockensubstanzmenge im Pansen sowie im Gastrointestinaltrakt ermitteln.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01945195
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...