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  • 1
    Electronic Resource
    Electronic Resource
    Distribution of calmodulin protein and mRNA in growing pollen tubes (1998)
    Springer
    Sexual plant reproduction 11 (1998), S. 131-139 
    Details
    ISSN: 1432-2145
    Keywords: Key words Calmodulin ; mRNA ; Calcium ; Pollen tube ; Agapanthus umbellatus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Pollen tube growth is a vital process for angiosperm fertilisation and is dependent on the presence of a tip-focused gradient of cytosolic free calcium ([Ca2+]c). In order to clarify some of the target molecules which convey the Ca2+ signal information, we investigated calmodulin distribution during tube growth. Fluorescently labelled calmodulin was pressure microinjected into pollen tubes and its distribution monitored by confocal microscopy. Calmodulin distributes evenly throughout the cell, but some of its binding sites form a V-shaped collar behind the apical region. This specific association dissipates upon growth arrest, and suggests an interaction of calmodulin with cytoskeletal-bound target proteins. The distribution of calmodulin mRNA was also analysed by microinjection of fluorescently labelled mRNA. No specific pattern was observed, with an even localisation in the body of tube and a lower concentration in the cell apex. Studies with localised application of inhibitors/activators indicate that calmodulin plays a crucial role in tip elongation but does not direct tube orientation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004970050130
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    Paper (German National Licenses)
    Fulltext
  • 2
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    Why P/OF should look for evidences of over-dense structures in solar flare hard X-ray sources (1986)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: White-light and hard X-ray (HXR) observations of two white-light flares (WLFs) show that if the radiative losses in the optical continuum are powered by fast electrons directly heating the WLF source, then the column density constraints imposed by the finite range of the electrons requires that the WLF consist of an over-dense region in the chromosphere, with density exceeding 10 to the 14th power/cu cm. Thus, we recommend that P/OF search for evidences of over-dense structures in HXR images obtained simultaneously with optical observations of flares.
    Keywords: SOLAR PHYSICS
    Type: NASA. Marshall Space Flight Center Solar Flares and Coronal Physics Using P(OF as a Research Tool; p 142-145
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 3
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    Characteristics of the white-light source in the 1981 April 24 solar flare (1985)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: Observations of the white-light solar flare event of April 24, 1981 are presented. The observations were carried out in the optical, hard X-ray, and radio wavelengths from land-based observatories and from the International Sun-Earth Explorer (ISEE-3) satellite. Time-intensity profiles were derived for three lines of continuum emissions. The derived profiles are interpreted in terms of the energetics of the flare, and the role of energetic electrons in the production of optical continuum emission is examined in detail.
    Keywords: SOLAR PHYSICS
    Type: AD-A153580 , AFGL-TR-85-0068 , Astrophysical Journal, Part 2 - Letters to the Editor (ISSN 0004-637X); 290; L45-L48
    Format: text
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    NASA TECHNICAL REPORTS
  • 4
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    Partial performance degradation of a remote sensor in a space environment, and some probable causes (1974)
    In:  Other Sources
    Details
    Publication Date: 2019-06-27
    Description: The Multispectral Scanner (MSS) was launched on the Earth Resources Technology Satellite (ERTS-1) on July 23, 1972. The MSS has two calibration systems, one internal and one external. Both calibration systems have shown strong, spectrally dependent performance degradation since launch. This paper presents details on the optical system of the MSS and data on the performance degradation as a function of both spectral interval and time in orbit. The history of the MSS during tests is traced, and it is shown that hydrocarbons from an external source may have been deposited on optical surfaces in the instrument. It is postulated that these contaminant coatings may have polymerized as a result of the exposure to UV light from the sun, increasing their blue absorbtion and accounting for the observed performance degradation.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Applied Optics; 13; May 1974
    Format: text
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    NASA TECHNICAL REPORTS
  • 5
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    In orbit sun calibration performance of Landsat-2 (1975)
    In:  Other Sources
    Details
    Publication Date: 2019-06-27
    Description: Sun calibration data from Landsat-2 are presented and compared with those from Landsat-1 (ERTS-1). The data support the hypothesis that organic contamination caused the poor performance of the Landsat-1 sun calibration mirror, since extra cleanliness precautions were taken with the Landsat-2 mirror. These precautions are described; of particular importance was the aluminum foil covering kept close to the reflective surfaces of the second mirror during the prelaunch period.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Applied Optics; 14; Sept
    Format: text
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    NASA TECHNICAL REPORTS
  • 6
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    Performance of optical surfaces in space. (1973)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: The Multispectral Scanner carried by the ERTS-1 satellite (launched on July 23, 1972) is a very high resolution line scanning imaging radiometer operating in the visible and near infrared spectral regions. The instrument contains optical surfaces that are exposed to both direct and reflected sunlight, and the reflectivity and transmission of some of these surfaces have decreased in orbit. Details of the optical system are explained, and data on the degradation are reviewed as a function of both spectral interval and time in orbit. The history of the scanner during testing (when hydrocarbons from an external source may have been deposited on the optical surfaces) is also examined, and a mechanism is postulated for the observed degradation in orbit.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Spring Meeting of the Optical Society of America; Mar 13, 1973 - Mar 16, 1973; Denver, CO
    Format: text
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    NASA TECHNICAL REPORTS
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