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  • ASTROPHYSICS  (6)
  • Gossypium hirsutum  (3)
  • Astronomy
  • Astrophysics
  • Spacecraft Design, Testing and Performance
  • 1985-1989  (9)
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  • 1
    ISSN: 1617-4623
    Schlagwort(e): Restriction fragment length polymorphisms ; Gossypium hirsutum ; Gene copy number ; Lea, vicilin, and legumin genes ; Tetraploidization
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary We have determined the copy number of 21 genes in an allotetraploid and several diploid species of cotton by gel and dot blot hybridization with cloned cDNAs. The legumin A, legumin B, and all 18 unique Lea (late embryogenesis-abundant) cDNA sequences isolated from the AD allotetraploid Gossypium hirsutum are present in one copy in A, D, E, and F diploid species and in two copies in G. hirsutum. Gel blot analysis of DNAs digested with EcoRI or BamHI usually detects different sized fragments in A and D diploids. Conservation of these restriction fragment length polymorphisms in G. hirsutum allows most of these fragments to be assigned to their respective subgenomes. Furthermore, both subgenomes in G. hirsutum can be distinguished from those in the interfertile allotetraploid G. barbadense. These results show that physical mapping of both sets of chromosomes in an allotetraploid should be possible by segregation analysis.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    Springer
    Plant molecular biology 9 (1987), S. 301-313 
    ISSN: 1573-5028
    Schlagwort(e): Gossypium hirsutum ; embryo culture ; two-dimensional gel electrophoresis ; alloallele expression
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract In earlier studies, only two major patterns of transcript accumulation were seen for 18 late embryogenesis abundant (Lea) gene families in cotton (Gossypium hirsutum L.) during embryogenesis and early germination. Each of these gene families probably comprises two active alloalleles. The two polypeptides encoded by seven of the Lea families can be distinguished, and analysis of their translation in vitro indicated that regulation of the homeologous transcript abundance was similar in each. In the present study, two-dimensional gel electrophoresis of polypeptides synthesized in excised embryos was employed to determine if LEA polypeptide synthesis is regulated at the translational level. The relative in vivo synthesis rate of each of the two polypeptides of 7 Lea families was compared with the relative concentration of their transcripts measured earlier by in vitro translation. For 4 families, the relative translational efficiencies of the homeologous mRNAs do not change during embryogenesis. However, there are changes of 1.5–3-fold in the other 3 families. The translation efficiencies of all transcripts of 9 of the Lea family mRNAs in vivo can be calculated from the fraction of total protein radioactivity incorporated in each LEA polypeptide family and the fractional abundance of Lea family transcripts measured by RNA dot hybridization. Lea mRNAs are found to be translated at near average rates throughout embryogenesis and early germination. These observations suggest that regulation of Lea gene expression at the translational level is minor.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 3
    Digitale Medien
    Digitale Medien
    Springer
    Plant molecular biology 7 (1986), S. 155-170 
    ISSN: 1573-5028
    Schlagwort(e): embryo maturation ; cDNA cloning ; Gossypium hirsutum ; hybrid-arrest translation ; abscisic acid ; embryo culture
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Earlier studies found that cotton (Gossypium hirsutum L.) cotyledons contain several mRNAs which are more abundant during late embryogenesis than in mid-embryogenesis or early germination. They are here termed ‘Late embryogenesis-abundant’ mRNAs, encoded by Lea loci. Complementary DNA clones for 18 such mRNA sequences, defined at a hybridization criterion of Tm-15°C, were identified in a mature embryo cDNA library by differential cDNA hybridization. At a lower hybridization criterion, some sequence homology was found within several of these cloned Lea mRNA sequences. Each Lea mRNA sequence comprises 0.04–1.3% of mature embryo poly(A)+ mRNA, a level ten-fold to several hundred-fold higher than in young embryo or 24 h seedling poly(A)+ mRNA. Of 18 Lea mRNA sequences examined in cultured young embryos, the level of at least 13 are specifically increased by exogenous abscisic acid (ABA), several to a level near that in normal mature embryos. However, the abundance of several of the sequences does not appear to be significantly modulated by ABA. The LEA polypeptides encoded by 10 Lea mRNA sequences were identified by hybrid-arrested translation. They include most of the late embryogenesis-abundant, ABA-inducible, polypeptides previously identified. Preliminary results suggest that many of the individual Lea mRNA sequences are transcribed from 1–3 genes in each of cotton's two subgenomes.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 4
    Publikationsdatum: 2011-08-19
    Beschreibung: Narrow-band images of an unusual swirl structure located near the center of the Puppis A supernova remnant are presented which reveal three overlapping filamentary systems of highly diverse composition. One is dominated by emission lines of nitrogen, one by oxygen, and one by sulfur. Spectra indicate that these small rings have high velocities and a corresponding kinematic age of less than 800 yr. Heavy-element abundances are extremely high and different in each system, some reminiscent of knots in Cas A, and others of circumstellar matter observed surrounding supernova 1987A. The youth and unusual chemistry lead to the suggestion that a second supernova has exploded within the shell of Puppis A, giving rise to the swirl structure.
    Schlagwort(e): ASTROPHYSICS
    Materialart: Nature (ISSN 0028-0836); 337; 48-50
    Format: text
    Standort Signatur Erwartet Verfügbarkeit
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  • 5
    Publikationsdatum: 2013-08-31
    Beschreibung: A program is described which measures the gravitational acceleration of antiprotons. This idea was approached from a particle physics point of view. That point of view is examined starting with some history of physics over the last 200 years.
    Schlagwort(e): ASTROPHYSICS
    Materialart: NASA, Relativistic Gravitational Experiments in Space; p 55-58
    Format: application/pdf
    Standort Signatur Erwartet Verfügbarkeit
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  • 6
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    Unbekannt
    In:  Other Sources
    Publikationsdatum: 2013-08-29
    Beschreibung: Numerical simulations of the structure of aggregates of grains in the solar system show they are fractals with low density and irregular shapes. Comet nuclei forming from a mixture of ice and dust grains are likely to have nonuniform composition as well as structure. Such a nucleus appears to account for observed characteristic of comets. The structure has significant implications for the evolution of cometary nuclei.
    Schlagwort(e): ASTROPHYSICS
    Materialart: ESA, Proceedings of the 20th ESLAB Symposium on the Exploration of Halley's Comet. Volume 3: Posters; p 523-524
    Format: text
    Standort Signatur Erwartet Verfügbarkeit
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  • 7
    Publikationsdatum: 2016-06-07
    Beschreibung: The Infrared Astronomical Satellite (IRAS) has given us the first completely unbiased sky-survey in the far-infrared with wavebands centered at 12, 25, 60 and 100 microns. The Taurus-Auriga complex was selected as the first molecular cloud to be investigated in this study. The Taurus clouds were defined as lying between 04h and 05h in R.A. and +16 to +31 degrees in Dec., then the IRAS point-source catalogue was searched for sources with good or moderate quality fluxes in all three of the shortest IRAS bands. The sources which were selected in this way were then classified into subgroups according to their IRAS colors. Taurus is generally believed to be an area of low-mass star formation, having no luminous O-B associations within or near to the cloud complex. Once field stars, galaxies and planetary nebulae had been removed from the sample only the molecular cloud cores, T Tauri stars and a few emission-line A and B stars remained. The great majority of these objects are pre-main sequence in nature and, as stated by Chester (1985), main sequence stars without excess far-infrared emission would only be seen in Taurus if their spectral types were earlier than about A5 and then not 25 microns. By choosing our sample in this way we are naturally selecting the hotter and thus more evolved sources. To counteract this, the molecular cloud core-criterion was applied to soruces with good or moderate quality flux at 25, 60 and 100 microns, increasing the core sample by about one third. The candidate protostar B335 is only detected by IRAS at 60 and 100 microns while Taurus is heavily contaminated by cirrus at 100 microns. This means that detection at 25 microns is also required with those at 60 and 100 microns to avoid confusing a ridge of cirrus with a genuine protostar. The far-infrared luminosity function of these sources is then calculated and converted to the visual band by a standard method to compare with the field star luminosity function of Miller and Scalo. The eventual aim of this work is to obtain far-infrared luminosity functions for a number of molecular clouds which are known to be forming low-mass stars and to investigate how the slope is affected by changes in the density and turbulence of material.
    Schlagwort(e): ASTROPHYSICS
    Materialart: NASA. Ames Research Center Summer School on Interstellar Processes; Abstracts of Contributed Papers; p 1-2
    Format: application/pdf
    Standort Signatur Erwartet Verfügbarkeit
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  • 8
    Publikationsdatum: 2019-06-28
    Beschreibung: A tool for exploring the evolution of X-ray emission from young SNRs is presented which employs a novel approach to the problem of time-dependent ionization in a shock-heated plasma. The solution of this problem is coupled to a spherically symmetric hydrodynamic calculation for the evolution of a point explosion in a uniform medium. The method is applied to Kepler's SNR, and two narrowly constrained classes of models which can simultaneously fit the spectral and morphological features of the object are found. One of these is a Sedov model in which the emission arises from shocked ambient gas, and the other is a reverse-shock model in which the SN ejecta is the dominant source of radiation. The emission from one specific model in each class is compared with the radial surface brightness profile, the 0.2-4.5 keV broadband spectrum, and the 1-3 keV moderate-resolution spectrum of the remnant. Reasonable fits are obtained in both cases.
    Schlagwort(e): ASTROPHYSICS
    Materialart: Astrophysical Journal, Part 1 (ISSN 0004-637X); 291; 544-560
    Format: text
    Standort Signatur Erwartet Verfügbarkeit
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  • 9
    Publikationsdatum: 2019-07-12
    Beschreibung: The medium energy X-ray detectors onboard the EXOSAT Observatory have been used to determine the gas temperature at several positions in the Coma Cluster of galaxies. Evidence is found at greater than 95 percent confidence for a higher temperature in the center of the cluster than in a position approximately 45 arcmin off-center. No difference in iron abundance is observed between the center and off-center regions and the equilibrium model for the distribution of elements in the Coma Cluster of Abramopoulos, Chanan, and Ku can be rejected with greater than 99.5 percent confidence, in favor of a model with more uniform composition. A phenomenological model is presented of the Coma Cluster, which is consistent with the data presented here, as well as the imaging data from the Einstein Observatory and the Tenma X-ray spectrum. The model has a central isothermal region of temperature about 9 keV extending to about 25 arcmin (about 1 Mpc). Beyond this radius the temperature falls as a polytrope with index about 1.6.
    Schlagwort(e): ASTROPHYSICS
    Materialart: Astrophysical Journal, Part 1 (ISSN 0004-637X); 329; 82-96
    Format: text
    Standort Signatur Erwartet Verfügbarkeit
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