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  • 1
    Electronic Resource
    Electronic Resource
    Methylation of the 5′ flanking sequences of the ribosomal DNA in human cell lines and in a human-hamster hybird cell line (1992)
    New York, N.Y. : Wiley-Blackwell
    Journal of Cellular Biochemistry 50 (1992), S. 357-362 
    Details
    ISSN: 0730-2312
    Keywords: rDNA ; lymphoblastoid ; methylation ; hypermethylation ; DNA ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: In human lymphoplastoid cell line (Z83) in which rDNA genes on chromosomes 22 are amplified but transcribed at a low level, immunocytological studies with antibodies to 5 methylcytidine provided evidence for hypermethylation of the rDNA. The extent of methylation of the 5′ flanking sequence of the ribosomal DNA was examined by comapring the size of restriciton fragments obtained by digestion of genomic DNA with EcoRI and Hpall or EcoRI and Mpsl. Southern blots indicated hypermethylation of the 5′ flanking sequences of many copies of rRNA genes in these cells, but not in a control lymphoblastoid cell line without rDNA amplification. Results obtained with somatic hybird human-hamster cell line, in which the rRNA genes on the single human chromosomes 22 are inactive, showed that only a small fraction of the CCGG sites in the 5′ flanking sequences of the transcriptionally silent rRNA genes in this hybird were methylated. Since inactive rRNA genes can show such a minimal level of methylation, it is likely that the extreme hypermethylation of the apmlified rRNA genes in Z83 association with their inactivation rather than following it. © 1992 Wiley-Liss, Inc.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcb.240500404
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  • 2
    Electronic Resource
    Electronic Resource
    Spontaneous fusion between metastatic mammary tumor subpopulations (1988)
    New York, N.Y. : Wiley-Blackwell
    Journal of Cellular Biochemistry 36 (1988), S. 129-136 
    Details
    ISSN: 0730-2312
    Keywords: hybrid cells ; metastasis ; heterogeneity ; generation of aneuploidy ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: This study describes a differential frequency of spontaneous fusion between metastatic and nonmetastatic subpopulations derived from a single mouse mammary tumor. Subpopulations 66, 66cl4 (a variant of 66 which is resistant to both thioguanine and ouabain), 410.4, and 44FTO (a thioguanine-resistant, ouabain-resistant derivative of 410.4) spontaneously metastasize from subcutaneous and mammary fatpad sites. Subpopulations 168, 168FARO (a diaminopurine-resistant, ouabain-resistant derivative of 168), 67, 68H, and 410 do not. The ability of these subpopulation lines to fuse spontaneously in vitro was determined after coculturing a drug-resistant line with a wild-type line in nonselective media. After 16-20 h of coculture, cells were plated in the appropriate media to select for fusion products - either HAT (hypoxanthine, aminopterin, thymidine) plus ouabain or AA (alanosine, adenine) plus ouabain - to determine the number of colony-forming cells (fusion products) present per 104 cells plated. When both subpopulations of the pair in the fusion mixture were metastatic, a significantly greater number of fusion products was recovered than if one or both of the subpopulations in the fusion mixture was nonmetastatic, with one exception: line 410 readily fused with both 66cl4 and 44FTO. Subline 410 was highly metastatic when originally isolated but lost its metastatic competence after a brief time in tissue culture.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcb.240360204
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  • 3
    Electronic Resource
    Electronic Resource
    Assessing tumor drug sensitivity by a new in vitro assay which preserves tumor heterogeneity and subpopulation interactions (1984)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 121 (1984), S. 105-116 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: We have designed an in vitro assay to assess the influence of tumor subpopulation interactions on drug response. The assay is based upon inhibition of growth of 1 mm3-pieces of tumor embedded in a collagen gel matrix. Tumor growth is quantitated by planimetry of each colony's image, formed with a split image tracing device attached to an inverted microscope. That expansion of the colonies in collagen gel represents growth through cell replication was demonstrated by releasing and counting cell nuclei. Outgrowths from pieces of tumors produced by a series of mouse mammary tumor subpopulation lines expanded in collagen gel at a rate characteristic of each cell line: the growth rate of tumor pieces was similar to that of the corresponding tumor line embedded as a cell bolus of cultured cells, indicating that growth of pieces of tumor is due to the tumor cells rather than to stromal components. When two cell lines were grown together in collagen cultures, interactions affecting growth rate were observed. Both tumor pieces and cell boluses from cultured cells of the relatively homogeneous cell lines displayed similar, characteristic sensitivities to adriamycin (ADR) in the collagen gel assay. Advantages of the collagen assay over cloning assays are (1) preservation of potential cellular interactions which may be important in assessing tumor drug sensitivity; (2) maximization of growth of all cell populations within the tumor, as compared to growth in agar; and (3) reflection of the zonal distribution of different subpopulations within tumors; and (4) simulation of the three-dimensional growth architecture found in vivo.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1041210413
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  • 4
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    Temperature Structure in the Perseus Cluster Core Observed with Hitomi (2018)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: The present paper investigates the temperature structure of the X-ray emitting plasma in the core of the Perseus cluster using the 1.8-20.0 keV data obtained with the Soft X-ray Spectrometer (SXS) onboard the Hitomi Observatory. A series of four observations were carried out, with a total effective exposure time of 338 ks and covering a central region _ 7 in diameter. The SXS was operated with an energy resolution of _5 eV (full width at half maximum) at 5.9 keV. Not only fine structures of K-shell lines in He-like ions but also transitions from higher principal quantum numbers are clearly resolved from Si through Fe. This enables us to perform temperature diagnostics using the line ratios of Si, S, Ar, Ca, and Fe, and to provide the first direct measurement of the excitation temperature and ionization temperature in the Perseus cluster. The observed spectrum is roughly reproduced by a single temperature thermal plasma model in collisional ionization equilibrium, but detailed line ratio diagnostics reveal slight deviations from this approximation. In particular, the data exhibit an apparent trend of increasing ionization temperature with increasing atomic mass, as well as small differences between the ionization and excitation temperatures for Fe, the only element for which both temperatures can be measured. The best-fit two-temperature models suggest a combination of 3 and 5 keV gas, which is consistent with the idea that the observed small deviations from a single temperature approximation are due to the effects of projection of the known radial temperature gradient in the cluster core along the line of sight. Comparison with the Chandra/ACIS and the XMM-Newton/RGS results on the other hand suggests that additional lower-temperature components
    Keywords: Astrophysics
    Type: GSFC-E-DAA-TN54095 , Publications of the Astronomical Society of Japan (ISSN 0004-6264) (e-ISSN 2053-051X); 70; 2
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  • 5
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    GRS 1739-278 Observed at Very Low Luminosity with XMM-Newton and NuSTAR (2016)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: We present a detailed spectral analysis of XMM-Newton and NuSTAR observations of the accreting transient black hole GRS1739278 during a very faint low hard state at 0.02% of the Eddington luminosity (for a distance of 8.5 kpc and a mass of 10 solar mass). The broadband X-ray spectrum between 0.5 and 60 keV can be well-described by a power-law continuum with an exponential cutoff. The continuum is unusually hard for such a low luminosity, with a photon index of =1.39+/-0.04. We find evidence for an additional reflection component from an optically thick accretion disk at the 98% likelihood level. The reflection fraction is low, with R(sub refl) = 0.043(exp + 0.033)(sub - 0.023). In combination with measurements of the spin and inclination parameters made with NuSTAR during a brighter hard state by Miller et al., we seek to constrain the accretion disk geometry. Depending on the assumed emissivity profile of the accretion disk, we find a truncation radius of 15-35 R(sub g) (5-12 R(sub ISCO)) at the 90% confidence limit. These values depend strongly on the assumptions and we discuss possible systematic uncertainties.
    Keywords: Astrophysics
    Type: GSFC-E-DAA-TN60680 , The Astrophysical Journal (ISSN 0004-637X) (e-ISSN 1538-4357); 832; 2; 115
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  • 6
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    The LOFT Mission Concept - A Status Update (2016)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: The Large Observatory For x-ray Timing (LOFT) is a mission concept which was proposed to ESA as M3 and M4 candidate in the framework of the Cosmic Vision 2015-2025 program. Thanks to the unprecedented combination of effective area and spectral resolution of its main instrument and the uniquely large field of view of its wide field monitor, LOFT will be able to study the behaviour of matter in extreme conditions such as the strong gravitational field in the innermost regions close to black holes and neutron stars and the supra-nuclear densities in the interiors of neutron stars. The science payload is based on a Large Area Detector (LAD, is greater than 8m2 effective area, 2-30 keV, 240 eV spectral resolution, 1 degree collimated field of view) and a Wide Field Monitor (WFM, 2-50 keV, 4 steradian field of view, 1 arcmin source location accuracy, 300 eV spectral resolution). The WFM is equipped with an on-board system for bright events (e.g., GRB) localization. The trigger time and position of these events are broadcast to the ground within 30 s from discovery. In this paper we present the current technical and programmatic status of the mission.
    Keywords: Astrophysics
    Type: GSFC-E-DAA-TN44111 , SPIE Astronomical Telescopes + Instrumentation; Jun 26, 2016 - Jul 01, 2016; Edinburgh, Scotland; United Kingdom|Space Telescopes and Instrumentation 2016: Ultraviolet to Gamma Ray; 9905; 99051R
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  • 7
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    Arcus: The X-Ray Grating Spectrometer Explorer (2016)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: Arcus will be proposed to the NASA Explorer program as a free-flying satellite mission that will enable high-resolution soft X-ray spectroscopy (8-50 Angstroms) with unprecedented sensitivity-effective areas of greater than 500 sq cm and spectral resolution greater than 2500. The Arcus key science goals are (1) to determine how baryons cycle in and out of galaxies by measuring the effects of structure formation imprinted upon the hot gas that is predicted to lie in extended halos around galaxies, groups, and clusters, (2) to determine how black holes influence their surroundings by tracing the propagation of out-flowing mass, energy and momentum from the vicinity of the black hole out to large scales and (3) to understand how accretion forms and evolves stars and circumstellar disks by observing hot infalling and outflowing gas in these systems. Arcus relies upon grazing incidence silicon pore X-ray optics with the same 12m focal length (achieved using an extendable optical bench) that will be used for the ESA Athena mission. The focused X-rays from these optics will then be diffracted by high-efficiency off-plane reflection gratings that have already been demonstrated on sub-orbital rocked flights, imaging the results with flight-proven CCD detectors and electronics. The power and telemetry requirements on the spacecraft are modest. The majority of mission operations will not be complex, as most observations will be long (~100 ksec), uninterrupted, and pre-planned, although there will be limited capabilities to observe targets of opportunity, such as tidal disruption events or supernovae with a 3-5 day turnaround. After the end of prime science, we plan to allow guest observations to maximize the science return of Arcus to the community.
    Keywords: Astrophysics
    Type: GSFC-E-DAA-TN43826 , Space Telescopes and Instrumentation 2016; Edinburgh; United Kingdom|Proceedings of SPIE (ISSN 0277-786X); 9905; 99054M
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  • 8
    Electronic Resource
    Electronic Resource
    Collapse of species boundaries in the wild potatoSolanum brevicaule complex (Solanaceae, S. sect.Petota): Molecular data (1999)
    Springer
    Plant systematics and evolution 214 (1999), S. 103-130 
    Details
    ISSN: 1615-6110
    Keywords: Solanaceae ; sect.Petota ; Solanum brevicaule ; Domestication ; hybridization ; potatoes ; systematics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract TheSolanum brevicaule complex is a group of morphologically very similar wild and cultivated potato taxa (Solanum sect.Petota). This study uses single to low-copy nuclear RFLPs and RAPDs to investigate their species boundaries and relationships. Cladistic analyses of both data sets are largely concordant with each other and with a recently published phenetic analyses of the same accessions using morphology. All three data sets separate members of the complex into populations from Peru and immediately adjacent northwestern Bolivia, including most cultivated species accessions, and populations from northwestern Bolivia to Argentina. The molecular results suggest that the complex is paraphyletic as currently circumscribed. Many species of theS. brevicaule complex should be relegated to synonymy.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00985734
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  • 9
    Electronic Resource
    Electronic Resource
    Musculature of the lacewing (chrysopa plorabunda) neuroptera (1933)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 55 (1933), S. 29-51 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: This article is an account of the complete musculature of an adult Neuropteran insect, Chrysopa plorabunda. Previous anatomical discussions on this order of insects include only a few of the muscles of the head and thoracic regions, while those of the abdomen are entirely lacking. The muscles here described include those of the head, thorax, and abdomen. The origin, insertion, and function of each muscle is given. The boundaries of several of the sclerites, especially those of the labium, are located by the observations on the musculature of these parts. The meso- and metathoracic wings are of the same size and for that reason the muscles of these regions are very much alike. The prothorax is greatly elonated, causing the muscles of that region to differ to a greater or less degree from the ‘general rule’ in insects. The abdominal muscles may be arranged in the several groups generally found in insects. In several cases, however, both the origin and insertion of the muscle have been shifted to accompany changes which have taken place in the abdominal segmentation. All of the muscles are shown in the four plates containing nineteen figures which accompany the text.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jmor.1050550104
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  • 10
    Electronic Resource
    Electronic Resource
    A comparative study of the contents of the gelatinous accumulations of the culture media and the contents of the cytoplasm of Amoeba proteus and Arcella vulgaris (1937)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 60 (1937), S. 325-359 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Comparative data give the basis for reinterpreting alleged chromidia, mitochondria and Golgi material described for certain rhizopods.Three distinct groups of granules can be demonstrated in both Amoeba and Arcella by techniques ordinarily employed for revealing chromatin elements of a cell, mitochondria or Golgi material. With respect to physico-chemical properties the granules appear identical with certain forms of bacteria in the culture media. They are not destroyed by alcohol, ether, or Altmann's fluid containing 5% acetic acid.These granules are apparently bacteria; two groups representing permanent cytoplasmic entities either as symbionts or commensals, the third possibly temporary invaders.None of the cytoplasmic inclusions of these rhizopods have given the characteristic mitochondrial reaction when treated with Janus green. Spherules and granules, or alleged Golgi material, in Amoeba blackened with osmic acid can be revealed by techniques ordinarily employed for demonstrating the chromatin elements of a cell. Similar spherules and granules occur in the gelatinous material of the culture media, free or in bodies similar to those sometimes found in food vacuoles.In Arcella, neutral-red-stainable and osmiophilic bodies, apparently identical with granules or small globules found individually distributed in the cytoplasm, can be observed both in food bodies in food vacuoles and in similar food organisms in the medium. Those occurring in the cytoplasm may represent indigestible material.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jmor.1050600203
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