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  • Hordeum vulgare  (2)
  • Chlorophyll fluorescence  (1)
  • Electron transport  (1)
  • Flight distance  (1)
  • Springer  (5)
Document type
Keywords
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  • Springer  (5)
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  • 1
    Electronic Resource
    Electronic Resource
    Honeybee navigation: linear perception of short distances travelled (1999)
    Springer
    Journal of comparative physiology 185 (1999), S. 239-245 
    Details
    ISSN: 1432-1351
    Keywords: Key words Odometry ; Flight distance ; Vision ; Perception
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Recent evidence indicates that honeybees measure distance flown to a food source by integrating, over time, the apparent visual motion of the environment that they experience en route to the goal. Is the bee's perception of distance travelled a linear function of distance, or is it some other function? This question was investigated by training bees to fly into a tunnel and receive a food reward. The walls and floor of the tunnel were lined with a random texture, and the reward was placed at one of two fixed distances, “near” or “far”, from the tunnel entrance. The feeder containing the reward was placed in a box which could be accessed through one of two openings, one on the left side of the box, and the other on the right. When the box was at the “near” position, the reward could only be accessed through the left-hand opening; when the box was at the “far” position, the reward could only be accessed through the right-hand opening. When the trained bees were tested individually in an identical, fresh tunnel with the reward removed from the box, they showed a strong preference for the left-hand opening when tested at the “near” distance, and for the right-hand opening when tested at the “far” distance. At intermediate positions, the bees' preference for the two openings varies linearly with distance. These findings suggest that the honeybee's perception of distance travelled is linear, at least over the distances and range of image motions experienced in our experiments. The implications for navigation and for the encoding of distance information in the dance are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003590050383
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  • 2
    Electronic Resource
    Electronic Resource
    A biochemical model of photosynthetic CO2 assimilation in leaves of C3 species (1980)
    Springer
    Planta 149 (1980), S. 78-90 
    Details
    ISSN: 1432-2048
    Keywords: Electron transport ; Leaf model ; Light and CO2 assimilation ; Ribulose bisphosphate carboxylase-oxygenase ; Temperature ; Photosynthesis (C3)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Various aspects of the biochemistry of photosynthetic carbon assimilation in C3 plants are integrated into a form compatible with studies of gas exchange in leaves. These aspects include the kinetic properties of ribulose bisphosphate carboxylase-oxygenase; the requirements of the photosynthetic carbon reduction and photorespiratory carbon oxidation cycles for reduced pyridine nucleotides; the dependence of electron transport on photon flux and the presence of a temperature dependent upper limit to electron transport. The measurements of gas exchange with which the model outputs may be compared include those of the temperature and partial pressure of CO2(p(CO2)) dependencies of quantum yield, the variation of compensation point with temperature and partial pressure of O2(p(O2)), the dependence of net CO2 assimilation rate on p(CO2) and irradiance, and the influence of p(CO2) and irradiance on the temperature dependence of assimilation rate.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00386231
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  • 3
    Electronic Resource
    Electronic Resource
    Photoinhibition of photosynthesis in intact bean leaves: role of light and temperature, and requirement for chloroplast-protein synthesis during recovery (1986)
    Springer
    Planta 168 (1986), S. 253-260 
    Details
    ISSN: 1432-2048
    Keywords: Chlorophyll fluorescence ; Light and photoinhibition ; Phaseolus (photoinhibition) ; Photoinhibition of photosynthesis (recovery) ; Temperature and photoinhibition
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Photoinhibition of photosynthesis was induced in intact leaves of Phaseolus vulgaris L. grown at a photon flux density (PFD; photon fluence rate) of 300 μmol·m-2·s-1, by exposure to a PFD of 1400 μmol·m-2·s-1. Subsequent recovery from photoinhibition was followed at temperatures ranging from 5 to 35°C and at a PFD of either 20 or 140 μmol·m-2·s-1 or in complete darkness. Photoinhibition and recovery were monitored mainly by chlorophyll fluorescence emission at 77K but also by photosynthetic O2 evolution. The effects of the protein-synthesis inhibitors, cycloheximide and chloramphenicol, on photoinhibition and recovery were also determined. The results demonstrate that recovery was temperature-dependent with rates slow below 15°C and optimal at 30°C. Light was required for maximum recovery but the process was light-saturated at a PFD of 20 μmol·m-2·s-1. Chloramphenicol, but not cycloheximide, inactivated the repair process, indicating that recovery involved the synthesis of one or more chloroplast-encoded proteins. With chloramphenicol, it was shown that photoinhibition and recovery occurred concomitantly. The temperature-dependency of the photoinhibition process was, therefore, in part determined by the effect of temperature on the recovery process. Consequently, photoinhibition is the net difference between the rate of damage and the rate of repair. The susceptibility of chilling-sensitive plant species to photoinhibition at low temperatures is proposed to result from the low rates of recovery in this temperature range.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00402971
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  • 4
    Electronic Resource
    Electronic Resource
    Apoptosis in barley aleurone during germination and its inhibition by abscisic acid (1996)
    Springer
    Plant molecular biology 32 (1996), S. 1125-1134 
    Details
    ISSN: 1573-5028
    Keywords: DNA fragmentation ; abscisic acid ; germination ; aleurone ; Hordeum vulgare
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract During germination of barley grains, DNA fragmentation was observed in the aleurone. The appearance of DNA fragmentation in the aleurone layer, observed by TUNEL staining in aleurone sections, started near the embryo and extended to the aleurone cells far from the embryo in a time dependent manner. The same spatial temporal activities of hydrolytic enzymes such as α-amylase were observed in aleurone. DNA fragmentation could also be seen in vitro under osmotic stress, in isolated aleurone. During aleurone protoplast isolation, a very enhanced and strong DNA fragmentation occurred which was not seen in protoplast preparations of tobacco leaves. ABA was found to inhibit DNA fragmentation occurring in barley aleurone under osmotic stress condition and during protoplast isolation, while the plant growth regulator gibberellic acid counteracted the effect of ABA. Addition of auxin or cytokinin had no significant effect on DNA fragmentation in these cells. To study the role of phosphorylation in ABA signal transduction leading to control of DNA fragmentation (apoptosis), the effects of the phosphatase inhibitor okadaic acid and of phenylarisine oxide on apoptosis were studied. We hypothesize that the regulation of DNA fragmentation in aleurone plays a very important role in spatial and temporal control of aleurone activities during germination. The possible signal transduction pathway of ABA leading to the regulation of DNA fragmentation is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00041396
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  • 5
    Electronic Resource
    Electronic Resource
    Apoptosis in developing anthers and the role of ABA in this process during androgenesis in Hordeum vulgare L. (1999)
    Springer
    Plant molecular biology 39 (1999), S. 489-501 
    Details
    ISSN: 1573-5028
    Keywords: anthers ; androgenesis ; DNA fragmentation ; abscisic acid ; Hordeum vulgare
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Intra-nucleosomal cleavage of DNA into fragments of about 200 bp was demonstrated to occur in developing anthers, in which microspores had developed into the mid-late to late uni-nucleate stage in situ, i.e. at the verge of mitosis. The same was observed, but to a much larger extent, if these anthers were pre- treated by a hyper-osmotic shock. Pretreatment of anthers before the actual culture of microspores was required for optimal androgenesis of microspores. The use of the TUNEL reaction, which specifically labels 3′ ends of DNA breaks, after intra-nucleosomal cleavage of DNA, revealed that DNA fragmentation mainly occurred in the loculus wall cells, tapetum cells and filament cells. TUNEL staining was absent or infrequently observed in the microspores of developing anthers in situ. Electron microscopy studies showed condensed chromatin in nuclei of loculus wall cells in the developing anthers. These observations at the chromatin and DNA level are known characteristics of programmed cell death, also known as apoptosis. Features of apoptosis were infrequently found in microspores from freshly isolated mature anthers. However, most tapetum cells had disappeared in these anthers and the remaining cell structures showed loss of cellular content. The viability of microspores in pre-treated anthers was comparable to those in freshly isolated anthers and almost four times higher than in anthers from control experiments. This observation was correlated with three to four times less microspores showing TUNEL staining and a two times higher level of ABA in the anther plus medium samples than in controls. Addition of ABA to the controls enhanced the viability and lowered the occurrence of apoptosis linked characteristics in the microspores. These data suggest that pre-treatment is effective in stimulating androgenesis because it leads to an increase in ABA levels which protects microspores from dying by apoptosis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006198431596
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