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  • 1
    Digitale Medien
    Digitale Medien
    Bound states and time-dependent dynamics of the N2H+ molecular ion in its ground electronic state. I. 2D treatment (1997)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 107 (1997), S. 2930-2941 
    Details
    ISSN: 1089-7690
    Quelle: AIP Digital Archive
    Thema: Physik , Chemie und Pharmazie
    Notizen: The ground-state potential energy surface (PES) for linear arrangements of the N2H+ molecular ion is numerically computed by the multireference single- and double-excitation configuration interaction (MRD-CI) technique. An analytical representation of the potential energy function is obtained by fitting a power series in the Simons–Parr–Finlan coordinates to the numerical data. For investigating the intramolecular dynamics we describe the nuclear motion by a Gaussian wave packet located initially in the strong interaction region of the PES. The vibrational eigenvalue spectrum is calculated by Fourier transforming the time autocorrelation function. The spectrum is then analyzed statistically in the light of random matrix theory (RMT) to understand the nature of the intramolecular dynamics. We examine the short-range correlation in the spectrum through the nearest neighbor level spacing distribution P(s) and the long-range correlation through Δ3 and Σ2 statistics. The spectrum in the time domain is analyzed by computing the ensemble averaged survival probability 〈〈P(t)〉〉. The above four quantities obtained from the spectrum are compared with the distribution predicted for regular, irregular, and mixed (intermediate) spectra by the RMT. We find the system is of mixed type and the fractional irregularity is 0.7±0.05. In order to reveal a possible correspondence to the classical dynamics, we have carried out the spectral analysis of the dynamical variables for classical trajectories over a wide range of internal energies. In addition the classical dynamics of proton collisions with N2 molecules has also been preliminarily studied on the same PES, in particular the dependence of the final vibrational action nf on the initial vibrational phase φi of N2 and, furthermore, the Poincaré surface-of-section superimposed with the zero-order separatrix; we find a large number of trapped trajectories. © 1997 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.474651
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  • 2
    Digitale Medien
    Digitale Medien
    Circular dichroism and magnetic circular dichroism of reduced molybdenum-iron protein of Azotobacter vinelandii nitrogenase (1981)
    s.l. : American Chemical Society
    Biochemistry 20 (1981), S. 2857-2864 
    Details
    ISSN: 1520-4995
    Quelle: ACS Legacy Archives
    Thema: Biologie , Chemie und Pharmazie
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1021/bi00513a023
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  • 3
    Digitale Medien
    Digitale Medien
    Relationships between the Crystalline and the Smectic C Structures of a Biforked Mesogen (1995)
    s.l. : American Chemical Society
    Chemistry of materials 7 (1995), S. 2252-2258 
    Details
    ISSN: 1520-5002
    Quelle: ACS Legacy Archives
    Thema: Chemie und Pharmazie , Maschinenbau
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1021/cm00060a011
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  • 4
    Digitale Medien
    Digitale Medien
    Evaluation of amplified fragment length polymorphism markers in tef, Eragrostis tef (Zucc.) Trotter, and related species (2000)
    Oxford, UK : Blackwell Publishing Ltd
    Plant breeding 119 (2000), S. 0 
    Details
    ISSN: 1439-0523
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Tef is an important cereal crop in Ethiopia. This study was conducted to investigate (1) genetic diversity within and among three Eragrostis species (E. tef, E. pilosa and E. curvula), and (2) the relationship between E. tef, E. pilosa and E. curvula. A total of 529 AFLP markers were obtained, out of which 58% (368) were polymorphic, using 10 primer, combinations. The three species were separated distinctly using amplified fragment length polymorphism (AFLP), However, diversity revealed at the morphological trait level was not commensurate with that observed for AFLP. This was due to the small number of morphological traits available and their interaction with the environment. Within tef, ‘Rubicunda’ and DZ-01-1093 were found to be distantly related to the rest of the tef accessions. The diversity within species was such that E. pilosa was the most diverse followed by E. curvula and E. tef. Moreover, E. pilosa was more closely related to E. tef than E. curvula. Therefore, further study is needed of E. pilosa accessions and of ‘Rubicunda’ and DZ-01-1093 in a crossing programme to generate a population for selection and/or genetic mapping. A total of 19 cultivars or accessions had one or more unique fragments using one or more AFLP primers, indicating the potential of the technology in fingerprinting tef in a breeding or seed multiplication programme.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1046/j.1439-0523.2000.00512.x
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  • 5
    Digitale Medien
    Digitale Medien
    Variation in root penetration ability, osmotic adjustment and dehydration tolerance among accessions of rice adapted to rainfed lowland and upland ecosystems (2001)
    Oxford, UK : Blackwell Publishing Ltd
    Plant breeding 120 (2001), S. 0 
    Details
    ISSN: 1439-0523
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Drought is the major constraint limiting rainfed rice production. The ability of rice roots to penetrate compacted soils and therefore to increase water extraction capacity, osmotic adjustment and dehydration tolerance of leaves enables the plant to tolerate drought. Experiments were conducted to determine the extent of genetic variation in root penetration index, osmotic adjustment and dehydration tolerance among indica accessions adapted to rainfed lowlands as well as traditional varieties from rainfed uplands. Root penetration index was evaluated in a system using wax–petrolatum layers to simulate soil compaction. Osmotic adjustment and dehydration tolerance were studied under slow development of water stress. Substantial genetic variation was found for root penetration index, osmotic adjustment and dehydration tolerance among indica ecotypes from lowlands, and the study of several traditional varieties from uplands showed variation in root penetration index and related root traits. An indica accession, IR58821-23-B-1-2-1 had a high root penetration index of 0.38. The accessions, IR61079-33-1-2-2-3, IR62266-42-6-2 and IR63919-38-B-1 had high osmotic adjustment capacities (1.91, 1.90 and 1.78 MPa, respectively); IR61079-33-1-2-2-3 also had high dehydration tolerance. Good osmotic adjustment and dehydration tolerance were associated with poor root system. The traditional varieties ‘Kallurundaikar’ and ‘Norungan’ had higher root penetration indices (0.46 and 0.43, respectively), than even the japonica accessions. The study identified indica accessions and traditional varieties with superior root- and shoot-related drought resistance traits that could be used in breeding for drought resistance in rice.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1046/j.1439-0523.2001.00578.x
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  • 6
    Digitale Medien
    Digitale Medien
    Stay green trait in grain sorghum: relationship between visual rating and leaf chlorophyll concentration (2000)
    Oxford, UK : Blackwell Publishing Ltd
    Plant breeding 119 (2000), S. 0 
    Details
    ISSN: 1439-0523
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Post-flowering drought tolerance is referred to as the stay green trait in sorghum. Plants with stay green resist drought-induced premature plant senescence. In breeding programmes, stay green is evaluated under limited irrigation, post-flowering moisture-stress field conditions and visually scored at or soon after physiological grain maturity. The objective of this study was to investigate the relationship between the stay green rating and total leaf chlorophyll content. The parents B35 and Tx7000, and their 98 F, recombinant inbred lines were evaluated in replicated field trials under limited (post-flowering stress) and full-irrigation (non-stress) conditions. After scoring the stay green trait of stressed plants, total leaf chlorophyll contents were measured with a chlorophyll meter (SPAD values) and a spectrophotometer method. The SPAD value had a significant linear relationship with total leaf chlorophyll (R2= 0.91) and with visual stay green rating (with R2= 0.82). Relative water content in top leaves of the stay green lines was about 81%, much higher than non-stay green lines (38%), indicating that the stay green lines kept the stalk transporting system functioning under severe drought conditions, The results indicate that visual stay green ratings were a reliable indicator of leaf senescence an should be useful to sorghum breeders in evaluating progeny when breeding for drought tolerance.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1046/j.1439-0523.2000.00506.x
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  • 7
    Digitale Medien
    Digitale Medien
    Heterochromatin differentiation and phylogenetic relationship of the A genomes in diploid and polyploid wheats (1989)
    Springer
    Theoretical and applied genetics 77 (1989), S. 84-94 
    Details
    ISSN: 1432-2242
    Schlagwort(e): Triticum ; Heterochromatin ; Wheat evolution ; Diploids ; Polyploids
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Heterochromatin differentiation, including band size, sites, and Giemsa staining intensity, was analyzed by the HKG (HCl-KOH-Giemsa) banding technique in the A genomes of 21 diploid (Triticum urartu, T. boeoticum and T. monococcum), 13 tetraploid (T. araraticum, T. timopheevi, T. dicoccoides and T. turgidum var. Dicoccon, Polonicum), and 7 cultivars of hexaploid (T. aestivum) wheats from different germplasm collections. Among wild and cultivated diploid taxa, heterochromatin was located mainly at centromeric regions, but the size and staining intensity were distinct and some accessions' genomes had interstitial and telomeric bands. Among wild and cultivated polyploid wheats, heterochromatin exhibited bifurcated differentiation. Heterochromatinization occurred in chromosomes 4At and 7At and in smaller amounts in 2At, 3At, 5At, and 6At within the genomes of the tetraploid Timopheevi group (T. araraticum, and T. timopheevi) and vice versa within those of the Emmer group (T. dicoccoides and T. turgidum). Similar divergence patterns occurred among chromosome 4Aa and 7Aa of cultivars of hexaploid wheat (T. aestivum). These dynamic processes could be related to geographic distribution and to natural and artifical selection. Comparison of the A genomes of diploid wheats with those of polyploid wheats shows that the A genomes in existing diploid wheats could not be the direct donors of those in polyploid wheats, but that the extant taxa of diploids and polyploids probably have a common origin and share a common A-genomelike ancestor.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00292321
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  • 8
    Digitale Medien
    Digitale Medien
    Inheritance of somatic embryogenesis and organ regeneration from immature embryo cultures of winter wheat (1989)
    Springer
    Theoretical and applied genetics 78 (1989), S. 137-142 
    Details
    ISSN: 1432-2242
    Schlagwort(e): Wheat ; Diallel analysis ; Somatic embryogenesis ; Plant regeneration ; In vitro culture
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Diallel analyses of F1 and reciprocal crosses among five winter wheat lines show that additive, non-additive, and cytoplasmic genetic effects were significant in the genetic control of somatic embryogenesis, shoot, and root induction frequencies as well as in numbers of somatic embryos, shoots, and roots. However, additive genetic effect appears to be most important since, in most cases a larger portion of the cross variation was accounted for by general combining ability. The results suggest that somatic embryogenesis and organ regeneration in winter wheat can be improved through genetic manipulation. Due to the presence of maternal effects, it may be critical to use a suitable genotype as a female parent in a selection program.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00299767
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  • 9
    Digitale Medien
    Digitale Medien
    Differences in the heat-shock response between thermotolerant and thermosusceptible cultivars of hexaploid wheat (1992)
    Springer
    Theoretical and applied genetics 84 (1992), S. 941-946 
    Details
    ISSN: 1432-2242
    Schlagwort(e): Triticum aestivum ; Genetic differences ; Heat-shock proteins ; Heat-shock response ; DNA polymorphism
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Heat-shock protein (HSP) gene expression in two wheat lines cv ‘Mustang’ (heat-tolerant) and cv ‘Sturdy’ (heat-susceptible) were analyzed to determine if wheat genotypes differing in heat tolerance also differ in in-vitro HSP synthesis (translatable HSP mRNAs) and steady-state levels of HSP mRNA. Several sets of mRNA were isolated from seedling leaf tissues which had been heat-stressed at 37 °C for various time intervals. These mRNAs were hybridized with HSP cDNA or genomic DNA probes (HSP17, 26, 70, 98, and ubiquitin). Protein profiles were compared using in-vitro translation and 2-D gels. The Northern slot-blot data from the heat-stress treatment provide evidence that the heat-tolerant cv ‘Mustang’ synthesized low molecular weight (LMW) HSP mRNA earlier during exposure to heat shock and at a higher level than did the heat-susceptible cv ‘Sturdy’. This was especially true for the chloroplast-localized HSP. The protein profiles shown by 2-D gel analysis revealed that there were not only quantitative differences of individual HSPs between the two wheat lines, but also some unique HSPs which were only found in the ‘Mustang’ HSP profiles. The high level of RFLP between the two wheat lines was revealed by Southern blot hybridization utilizing a HSP17 probe. These data provide a molecular basis for further genetic analysis of the role of HSP genes in thermal tolerance in wheat.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00227407
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  • 10
    Digitale Medien
    Digitale Medien
    Genetic diversity among elite Sorghum lines revealed by restriction fragment length polymorphisms and random amplified polymorphic DNAs (1994)
    Springer
    Theoretical and applied genetics 87 (1994), S. 816-820 
    Details
    ISSN: 1432-2242
    Schlagwort(e): Molecular markers ; Sorghum bicolor ; Phenetics ; Genetic diversity
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The genetic diversity of sorghum, as compared to corn, is less well characterized at the genetic and molecular levels despite its worldwide economic importance. The objectives of this study were to: (1) investigate genetic diversity for restriction fragment length polymorphism (RFLPs) and random amplified polymorphic DNAs (RAPDs) in elite sorghum lines, (2) compare similarities based on molecular markers with pedigree relationships, and (3) examine the potential of RFLPs and RAPDs for assigning sorghum lines to the A/B (sterile) and R (restorer) groups. Using four restriction enzymes, polymorphism was detected with 61% of the RFLP probes used, compared to 77% of the random primers. One hundred and sixteen (64%) probe-enzyme combinations yielded multiple-band profiles compared to 98% of the random primers. RFLP profiles generated 290 polymorphic bands compared to 177 polymorphic RAPDs. Pair-wise comparisons of polymorphic RFLPs and RAPDs were used to calculate Nei and Jaccard coefficients. These were employed to generate phenograms using UPGMA and neighborjoining clustering methods. Analysis of RFLP data with Jaccard's coefficient and neighbor-joining clustering produced the phenogram with the closest topology to the known pedigree.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00221133
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