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  • 1
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Group
    Nature 437 (2005), S. 253-256 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Antagonistic coevolution between hosts and parasites in spatially structured populations can result in local adaptation of parasites; that is, the greater infectivity of local parasites than foreign parasites on local hosts. Such parasite specialization on local hosts has implications for human ...
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  • 2
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of the World Aquaculture Society 31 (2000), S. 0 
    ISSN: 1749-7345
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: With the advent of sea cucumber aquaculture in the South Pacific region, a reliable method is needed to induce large numbers of animals to spawn in captivity. Broodstock of the sea cucumber Holothuria scabra, collected from Stradbroke Island, Moreton Bay (27°90′N, 153°24′E) Australia, during the reproductive season from October to January, were used in spawning trials. During the 1997–1998 summer between one to five weeks of captivity, 100% of animals were induced to spawn in four trials at dusk on or close to a new or full moon, using nine males and nine females contained in a Reln tank and 30 cm of filtered sea water, using a 3–5 C temperature shock. H. scabra was induced to spawn in small numbers during the 1996–1997 summer despite a marked degree of weight loss, and all animals spawned during 1997–1998 with minimal loss of weight. The difference in the number of spawned eggs between animals of similar size and mean numbers of spawned eggs in consecutive trials decreased the longer animals were held in captivity before spawning. The hatch rate of eggs was reduced significantly for broodstock held for more than one month. Hatch rate and numbers of spawned eggs are important indicators of egg viability of broodstock maintained in captivity for an extended period.
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Current genetics 2 (1980), S. 87-93 
    ISSN: 1432-0983
    Keywords: Protoplast fusion ; Kluyveromyces ; Hybrid characterization ; Stable Diploids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The technique of protoplast fusion has been applied to the problem of unstable diploidy in the yeast Kluyveromyces lactis. By protoplast fusion between heterothallic strains of like mating-type, sporulation-deficient hybrids can be obtained. Biochemical, cytological, and genetical characterisation of these hybrids suggests that the majority of fusion products are diploid. Sporulating hybrids can be constructed by protoplast fusion between homothallic strains. Tetrad analysis of these hybrids demonstrates conclusively the diploid nature of fusion products.
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  • 4
    ISSN: 1617-4623
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Protoplast fusion has provided us with a means of genetical analysis in respiratory-deficient mutants of the petite-negative yeast, Kluyveromyces lactis. Demonstration of mitochondrial-inheritance in respiratory-deficient mutants of petite-negative yeasts has not previously been possible due to the inviability of petite/microcolony cells.
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Molecular genetics and genomics 164 (1978), S. 185-193 
    ISSN: 1617-4623
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary 1. Inhibition of mitochondrial protein synthesis in the petite-negative yeast Kluyveromyces lactis leads to: (i) inhibition of growth in glucose and glycerol, and (ii) loss of antimycin-sensitive respiration and oxidative phosphorylation. 2. Loss of antimycin-sensitive respiration results in complete inhibition of growth in glycerol and partial inhibition of growth in glucose. 3. The extent to which glucose-growth is inhibited by loss of mitochondrial protein synthesis and/or antimycin-sensitive respiration is found to be strain dependent. The strain differences are explained in terms of different requirements for antimycin-sensitive respiration and oxidative phosphorylation in cell growth and division. However, growth-inhibition by erythromycin cannot be entirely accounted for by respiratory-dependence. 4. K. lactis is shown to possess antimycin-insensitive respiration and a cyanide/azide-insensitive respiration. Inhibition of mitochondrial protein synthesis does not lead to loss or change in these alternative respirations, suggesting an extramitochondrial origin for the components of these pathways. The significance of alternative respiration in yeasts is discussed. 5. Use of an erythromycin-resistant mutant of K. lactis demonstrates that there is no cross-resistance to chloramphenicol in this yeast strain.
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  • 6
    ISSN: 1573-5028
    Keywords: antifungal ; antimicrobial ; ethylene ; glucuronidase ; peptide
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The plant defensin PDF1.2 has previously been shown to accumulate systemically via a salicylic acid-independent pathway in leaves of Arabidopsis upon challenge by fungal pathogens. To further investigate the signalling and transcriptional processes underlying plant defensin induction, a DNA fragment containing 1184 bp and 1232 bp upstream of the transcriptional and translational start sites, respectively, was cloned by inverse PCR. To test for promoter activity this DNA fragment was linked to the β-glucuronidase (GUS)-encoding region of the UidA gene as a translational fusion and introduced into Arabidopsis ecotype C-24. Challenge of the transgenic plants with the fungal pathogens Alternaria brassicicola and Botrytis cinerea resulted in both local and systemic induction of the reporter gene. Wounding of the transgenic plants had no effect on GUS activity. Treatment of the transgenic plants with either jasmonates or the active oxygen generating compound paraquat strongly induced the reporter gene. In contrast, neither salicylate nor its functional analogues 2,6-dichloroisonicotinic acid and 1,2,3-benzothiodiazole-7-carbothioic acid S-methyl ester resulted in reporter gene induction. These results are consistent with the existence of a salicylic acid-independent signalling pathway, possibly involving jasmonates as regulators, that is triggered by pathogen challenge but not by wounding. The transgenic plants containing the PDF1.2-based promoter-reporter construct will provide useful tools for future genetic dissection of this novel systemic signalling pathway.
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  • 7
    Publication Date: 2021-10-14
    Description: A method is presented for the measurement of the phase gradient of a wavefront by tracking the relative motion of speckles in projection holograms as a sample is scanned across the wavefront. By removing the need to obtain an undistorted reference image of the sample, this method is suitable for the metrology of highly divergent wavefields. Such wavefields allow for large magnification factors that, according to current imaging capabilities, will allow for nanoradian angular sensitivity and nanoscale sample projection imaging. Both the reconstruction algorithm and the imaging geometry are nearly identical to that of ptychography, except that the sample is placed downstream of the beam focus and that no coherent propagation is explicitly accounted for. Like other X-ray speckle tracking methods, it is robust to low-coherence X-ray sources, making it suitable for laboratory-based X-ray sources. Likewise, it is robust to errors in the registered sample positions, making it suitable for X-ray free-electron laser facilities, where beam-pointing fluctuations can be problematic for wavefront metrology. A modified form of the speckle tracking approximation is also presented, based on a second-order local expansion of the Fresnel integral. This result extends the validity of the speckle tracking approximation and may be useful for similar approaches in the field.
    Keywords: 550 ; X-ray speckle tracking ; ptychography ; phase retrieval ; wavefront metrology ; in-line projection holography
    Language: English
    Type: map
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  • 8
    Publication Date: 2021-12-03
    Description: In recent years, X-ray speckle-tracking techniques have emerged as viable tools for wavefront metrology and sample imaging applications. These methods are based on the measurement of near-field images. Thanks to their simple experimental setup, high angular sensitivity and compatibility with low-coherence sources, these methods have been actively developed for use with synchrotron and laboratory light sources. Not only do speckle-tracking techniques give the potential for high-resolution imaging, but they also provide rapid and robust characterization of aberrations of X-ray optical elements, focal spot profiles, and sample position and transmission properties. In order to realize these capabilities, software implementations are required that are equally rapid and robust. To address this need, a software suite has been developed for the ptychographic X-ray speckle-tracking technique, an X-ray speckle-based method suitable for highly divergent wavefields. The software suite is written in Python 3, with an OpenCL back end for GPU and multi-CPU core processing. It is accessible as a Python module, through the command line or through a graphical user interface, and is available as source code under Version 3 or later of the GNU General Public License.
    Keywords: 548 ; software ; wavefront metrology ; speckle tracking ; ptychography ; X-ray projection imaging
    Language: English
    Type: map
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  • 9
  • 10
    Publication Date: 2019
    Electronic ISSN: 2052-4463
    Topics: Nature of Science, Research, Systems of Higher Education, Museum Science
    Published by Springer Nature
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