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  • 11
    Electronic Resource
    Electronic Resource
    Springer
    Genetic resources and crop evolution 26 (1978), S. 303-327 
    ISSN: 1573-5109
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Description / Table of Contents: Summary In addition to the previously reported observations results are presented on relations between essential breeding characteristics and the way of seed formation inPoa pratensis. The findings can be summarized as follows: 1. Within the studied material no correlations are existing between the own performance (yield of green matter) of the plants and the way of their reproduction. However, seed descendants of amphimictic individuals are distinctly more weak in growth than those out of apomictic plants. 2. The correlation coefficients between “number of chromosomes” and “yield”,r s=+0,19 andr s= −0,04, are not significant. Weak plants occurred within the total range of number of chromosomes recorded (2n=36 to 2n=118). The hybrids strong in growth may be found mainly in the range between 2n=70 and 2n=94 chromosomes. 3. Apomictic (non-segregating) as well as amphimictic (segregating) plants occurred over a wide range of number of chromosomes. The mean values of both groups do not differ significantly. 4. The correlation coefficients between “way of reproduction” and “frequency of polyembryos”,r s=−0,24 andr s=−0,32, are significant. Thet-test showed, however, that the frequencies of twins between descendants of apomictic and amphimictic plants do not differ significantly. Therefore it must be supposed that the registration of polyembryos does not give a reliable measure for recognizing the degree of apomictic or amphimictic seed formation, respectively. 5. In comparison between hybrids ofPoa pratensis which were propagated by apomictically arisen seeds or vegetativly a remarkable yield depression could be observed after triplicate vegetative propagation which was obviously not caused by the recorded diseases.
    Abstract: Краткое содержание В дополнение к наблюд ениям надPoa pratensis, о которых уже сообщалось в первой части этой ра боты, рассматриваютс я связи между признаками важ ными для селекции и типом о бразования семян. Рез ультаты сводятся к следующему. 1. В пределах исследова нного материала, корр еляции между вегетативной продуктивностью рас тений и типом их размн ожения, не найдено. Однако растения из семян, зав язавшихся половым пу тём, оказываются заметно слабее в росте, чем рас тения выросшие из сем ян, образовавшихся апом иктически. 2. Коэффициенты коррел яции между числом хро мосом и урожаем,r s=+0,19 иr s=−0,04, не отличаются до стоверно от нуля. Мало рослые растения обнаружены во всём ис следованном материа ле с числом хромосом от 2n= 36 до 2n=118. Рослые гибриды в стречаются среди рас тений с хромосомными числами между 2n=70 и 2n=94. 3. Апомиктические (не да ющие расщепления) и амфимиктические (даю щие расщепляющееся пото мство) растения обнар уживаются в очень широком диапозоне хромосомн ых чисел. Средние знач ения обеих групп не показывают статистически досто верного различия. 4. Для связи между типом размножения и частот ой проявления полиэмбр ионии получены, достоверно отличающиеся от нуля, коэффициенты рангов ой корреляции,r s=−0,24 иr s=−0,32. П оскольку частота «двойней» у апомикти ческих и амфимиктических ра стений не различаютс я достоверно (тестt), следует считат ь, что путём учёта полиэмбрионии нельз я делать заключений о половом или бесполом образов ании семян. 5. В сравнении с растени ями, возникшими путём апомиксиса у гибридо вPoa pratensis после троекратног о вегетативного размножения наблюда лся значительный спад ур ожайности, который оч евидно не был обусловлен зарегистрированным и болезнями.
    Notes: Zusammenfassung In Ergänzung zu den in Teil I dieser Serie mitgeteilten Beobachtungen beiPoa pratensis werden Ergebnisse über Beziehungen zwischen züchterisch wichtigen Merkmalen und der Art der Samenausbildung mitgeteilt. Sie lassen sich wie folgt zusammenfassen: 1. In dem untersuchten Material besteht keine Korrelation zwischen der Eigenleistung der Pflanzen und der Art ihrer Fortpflanzungsweise. Die aus sexuell entstandenen Samen stammenden Nachkommen sind jedoch deutlich schwachwüchsiger als die Pflanzen, die aus apomiktisch ausgebildeten Samen aufgezogen worden sind. 2. Die für die Beziehung „Chromosomenzahl“ und „Ertrag“ ermittelten Korrelationskoeffizientenr s=+0,19 undr s=−0,04 sind nicht signifikant. In dem gesamten erfaßten Chromosomenzahlenbereich von 2n=36 bis 2n=118 sind schwachwüchsige Pflanzen zu finden. Die Chromosomenzahlen der starkwüchsigen Hybriden sind bevorzugt in dem Bereich zwischen 2n=70 und 2n=94 anzutreffen. 3. Apomiktische (nichtspaltende) Pflanzen und amphimiktische (spaltende) Pflanzen treten über einen größeren Chromosomenzahlenbereich auf. Die Mittelwerte für beide Gruppen sind nicht signifikant verschieden. 4. Für die Beziehung „Art der Fortpflanzungsweise“ und „Frequenz Polyembryonen“ wurden signifikante Korrelationskoeffizienten vonr s=−0,24 und −0,32 erhalten. Aus der Tatsache, daß nach demt-Test die Zwillingsfrequenz zwischen apomiktischen und amphimiktischen Pflanzen nicht signifikant verschieden ist, muß jedoch angenommen werden, daß mittels Erfassung der Polyembryonen nicht auf den Grad der sexuellen bzw. asexuellen Samenausbildung geschlossen werden kann. 5. Im Vergleich zu einer dreimaligen Samenvermehrung ohne Selektion trat bei den Hybriden vonPoa pratensis nach dreimaliger vegetativer Vermehrung ein beachtlicher Ertragsabfall auf, der offensichtlich nicht, soweit erfaßt, durch Krankheiten verursacht wurde.
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  • 12
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 16 (1995), S. 454-464 
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: We present a computational method for prediction of the conformation of a ligand when bound to a macromolecular receptor. The method is intended for use in systems in which the approximate location of the binding site is known and no large-scale rearrangements of the receptor are expected upon formation of the complex. The ligand is initially placed in the vicinity of the binding site and the atomic motions of the ligand and binding site are explicitly simulated, with solvent represented by an implicit solvation model and using a grid representation for the bulk of the receptor protein. These two approximations make the method computationally efficient and yet maintain accuracy close to that of an all-atom calculation. For the benzamidine/trypsin system, we ran 100 independent simulations, in many of which the ligand settled into the low-energy conformation observed in the crystal structure of the complex. The energy of these conformations was lower than and well-separated from that of others sampled. Extensions of this method are also discussed. © 1995 by John Wiley & Sons, Inc.
    Additional Material: 4 Ill.
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  • 13
    Publication Date: 2019-01-16
    Description: A common design principle of heteromeric signaling proteins is the use of shared subunits. This allows encoding of complex messages while maintaining evolutionary flexibility. How cells regulate and control assembly of such composite signaling proteins remains an important open question. An example of particular complexity and biological relevance is the interleukin 12 (IL-12) family. Four functionally distinct αβ heterodimers are assembled from only five subunits to regulate immune cell function and development. In addition, some subunits act as independent signaling molecules. Here we unveil key molecular mechanisms governing IL-27 biogenesis, an IL-12 family member that limits infections and autoimmunity. In mice, the IL-27α subunit is secreted as a cytokine, whereas in humans only heterodimeric IL-27 is present. Surprisingly, we find that differences in a single amino acid determine if IL-27α can be secreted autonomously, acting as a signaling molecule, or if it depends on heterodimerization for secretion. By combining computer simulations with biochemical experiments, we dissect the underlying structural determinants: a protein folding switch coupled to disulfide bond formation regulates chaperone-mediated retention versus secretion. Using these insights, we rationally change folding and assembly control for this protein. This provides the basis for a more human-like IL-27 system in mice and establishes a secretion-competent human IL-27α that signals on its own and can regulate immune cell function. Taken together, our data reveal a close link between protein folding and immunoregulation. Insights into the underlying mechanisms can be used to engineer immune modulators.
    Print ISSN: 0027-8424
    Electronic ISSN: 1091-6490
    Topics: Biology , Medicine , Natural Sciences in General
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  • 14
    Publication Date: 2019-03-01
    Print ISSN: 1951-6355
    Electronic ISSN: 1951-6401
    Topics: Physics
    Published by Springer
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  • 15
    Publication Date: 2003-04-01
    Print ISSN: 1089-5639
    Electronic ISSN: 1520-5215
    Topics: Chemistry and Pharmacology , Physics
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  • 16
    Publication Date: 2010-07-08
    Print ISSN: 1520-6106
    Electronic ISSN: 1520-5207
    Topics: Chemistry and Pharmacology , Physics
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  • 17
    Publication Date: 2006-06-01
    Print ISSN: 0002-7863
    Electronic ISSN: 1520-5126
    Topics: Chemistry and Pharmacology
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  • 18
    Publication Date: 2008-02-21
    Print ISSN: 1549-9618
    Electronic ISSN: 1549-9626
    Topics: Chemistry and Pharmacology
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  • 19
    Publication Date: 2018-07-23
    Description: We describe a tethered multifluorophore motion assay based on DNA origami for revealing bimolecular reaction kinetics on the single-molecule level. Molecular binding partners may be placed at user-defined positions and in user-defined stoichiometry; and binding states are read out by tracking the motion of quickly diffusing fluorescent reporter units. Multiple dyes per reporter unit enable singe-particle observation for more than 1 hour. We applied the system to study in equilibrium reversible hybridization and dissociation of complementary DNA single strands as a function of tether length, cation concentration, and sequence. We observed up to hundreds of hybridization and dissociation events per single reactant pair and could produce cumulative statistics with tens of thousands of binding and unbinding events. Because the binding partners per particle do not exchange, we could also detect subtle heterogeneity from molecule to molecule, which enabled separating data reflecting the actual target strand pair binding kinetics from falsifying influences stemming from chemically truncated oligonucleotides. Our data reflected that mainly DNA strand hybridization, but not strand dissociation, is affected by cation concentration, in agreement with previous results from different assays. We studied 8-bp-long DNA duplexes with virtually identical thermodynamic stability, but different sequences, and observed strongly differing hybridization kinetics. Complementary full-atom molecular-dynamics simulations indicated two opposing sequence-dependent phenomena: helical templating in purine-rich single strands and secondary structures. These two effects can increase or decrease, respectively, the fraction of strand collisions leading to successful nucleation events for duplex formation.
    Print ISSN: 0027-8424
    Electronic ISSN: 1091-6490
    Topics: Biology , Medicine , Natural Sciences in General
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  • 20
    Publication Date: 2015-08-01
    Print ISSN: 0969-2126
    Electronic ISSN: 1878-4186
    Topics: Biology , Medicine
    Published by Cell Press
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