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  • 1
    ISSN: 1432-1203
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Description / Table of Contents: Zusammenfassung Eine Familie mit 2 autoptisch gesicherten Neuroblastomen, einem Ganglioneuroblastom und Hinweisen auf 3 weitere Neuroblastome wurde cytogenetisch untersucht. Anlaß war der von Sandberg et al. (1972) mitgeteilte Befund von double-minute-Chromosomen in Lymphocyten des peripheren Blutes bei einem Neuroblastom. Die Untersuchung sollte klären, ob in dieser “Neuroblastom-Familie” eine chromosomale Aberration als erbliche Vorschädigung die Entstehung von Sympathicustumoren begüngstigt. Es fanden sich keine konstanten Chromosomenanomalien, auch keine double-minute-Chromosomen.
    Notes: Summary A cytogenetic investigation was performed in a family which included 2 individuals with congential neuroblastomas of the suprarenal gland confirmed by autopsy and one with a ganglioneuroblastoma of the thoracic wall as well as 3 other individuals with tumors which probably were also neuroblastomas. The lymphocytes of the peripheral blood of 5 healthy relatives as well as of the child with the treated ganglioneuroblastoma failed to show a constant alteration of chromosomes. In this family, therefore, the suggestion could not be proofed that the very rate familial aggregation of neuroblastomas is caused by a hereditary chromosomal aberration.
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Theoretical and applied genetics 48 (1976), S. 23-34 
    ISSN: 1432-2242
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The course of meiosis in higher plants is controlled by a large number of genes, the function of which can be discerned by means of mutants showing any kind of meiotic anomaly. In general, there are three main groups of genes belonging to this system. The as-genes control the pairing behaviour of the homologous chromosomes, causing asynapsis in the mutated condition. The ds-genes are responsible for chiasma formation and chiasma frequency, causing desynapsis in the mutated condition. As- and ds-genes influence micro- and macrosporogenesis in a similar way but the ms-genes become effective only in microsporogenesis, resulting in a complete breakdown of meiosis at a stage specific for each gene of the group. In Pisum sativum, 58 mutants showing genetically conditioned meiotic anomalies have been cytogenetically analysed: 34 of them belong to the ds- and 7 to the as-group; one gene causes asynaptic as well as desynaptic effects; 13 genotypes are male sterile due to degeneration of the chromosomes; the remaining 3 genes cause less specific meiotic disturbances. The lethality of a mutant can be overcome by distinct environmental conditions but the mutant is sterile because of manifold meiotic anomalies. One gene in the Pisum genome controls the transition from the vegetative to the reproductive stage of the plants. Other genes influence the differentiation of the growing points in such a way that the sporogenic tissues are not formed. In these mutants, no sporocytes are present which can undergo meiosis. From the findings available for many species of the plant kingdom, it can be assumed that hundreds of genes controlling meiosis are present in the genome of each higher plant.
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  • 3
    ISSN: 1432-2242
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Zusammenfassung In konjugationsgestörten Mutanten treten im Verlaufe der Meiosis Univalente oder Univalente und Bivalente in wechselnden Häufigkeitsverhältnissen zueinander auf. Ihre räumliche Anordnung im Spindelraum der Metaphase I wurde zytologisch untersucht und die Befunde statistisch ausgewertet. Der überwiegende Teil unseres Materials ließ sich einheitlich durch eine Polya-Verteilung charakterisieren. Für deren Parameter wurden — für jeden Genotyp und für jede Univalentenklasse getrennt —Punkt-und Intervallschätzungen nach der Maximum Likelihood-Methode durchgeführt. Aus der Lage der Schätzwerte konnten wir schließen, daß bei allen untersuchten Mutanten die Wahrscheinlichkeit für die Univalente, sich in der Metaphaseplatte einzuordnen, um so größer wird, je mehr Bivalente in der Zelle vorliegen. Die gegenseitige Beeinflussung der Univalente ist bei unseren Mutanten unterschiedlich. Bei einer geringen Anzahl von Bivalenten erhöht jedes zufällig in der Metaphaseplatte angeordnete Univalent die Wahrscheinlichkeit für die übrigen, sich ebenfalls dort einzuordnen. Ist die Zahl der Bivalente erhöht, so nimmt die gegenseitige Beeinflussung der Univalente in einigen Fällen ab, in anderen Fällen bleibt sie lediglich erhalten. Es wurde zum Schluß versucht, die erarbeiteten Befunde als univalentenbedingte strukturelle und funktioneile Änderungen im Aufbau des Spindelapparates zu erklären.
    Notes: Summary Asynaptic and desynaptic mutants are characterized by the appearance of univalents in the course of meiosis. Their spatial arrangement in the spindle apparatus of metaphase I was cytologically investigated and the findings were statistically analysed. The great majority of our material could be fitted to a Polya-distribution. For the parameters of this distribution, point- and intervalestimations were performed by the maximum likelihood method, separately for each genotype and each univalent class. From the position of the estimates in the different classes, it can be concluded that in all genotypes under consideration a high number of bivalents increases the probability of the remaining univalents being arranged in the metaphase plate. The mutual interference of the univalents themselves differs from genotype to genotype: when the number of bivalents is low, each univalent that happens to be arranged in the metaphase plate raises the probability that the remaining univalents will migrate into the metaphase plate, too. In some cases, the mutual interference of the univalents is reduced when the number of bivalents increases; in other cases this interference is merely maintained. Finally, we tried to interpret the cytological and statistical findings by structural and functional changes of the spindle apparatus brought about by the existence of univalents.
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  • 4
    ISSN: 1434-6036
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The small splitting of the4 A 2 ground state of Cr3+ centers in Al2O3 has been measured with an EPR spectrometer in the temperature range from 88 K to 575 K. It is shown that the temperature dependence of this zero-magnetic-field splitting of about 2D=0.38 cm−1 is due to the thermal expansion of the lattice. It is found that $$\frac{{\partial \ln D}}{{\partial \ln R}} = 6.18$$ whereR is the interparticle distance. A new calculation of the ground state splitting is then used to explain this number as well as the splitting itself. Crystal field parameters are taken from optical measurements and from theg-factors.
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  • 5
    ISSN: 1434-6036
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Protoplasma 100 (1979), S. 33-43 
    ISSN: 1615-6102
    Keywords: Amoeba proteus ; Ca++-binding sites ; Cytochemical demonstration ; Induced pinocytosis ; Plasma membrane
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Different methods were used to demonstrate the existence of Ca++-binding sites (Ca++-bs) at the plasma membrane ofAmoeba proteus. In pinocytoting animals the number (indicated by the average distanced in nm) and size (average longitudinal axiss in nm) of Ca++-bs at the cytoplasmic surface of the cell membrane were significantly increased (d=162±15;n=41 ands=93±5;n=47) in comparison to controls (d=208 ±21;n=37 ands=59±8;n=45). The ratio of P: Ca obtained by X-ray microanalysis was in the range of 1.5. The differences observed in the two experimental groups of amoebae are explained by conformational changes in the molecular structure and an increased Ca++-permeability of the plasma membrane during induced pinocytosis. Microplasmodia of the acellular slime moldPhysarum polycephalum investigated for comparison were found to have no Ca++-bs at the interior cell surface.
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  • 7
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 45 (1979), S. 0 
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Free and total putrescine and, to a lesser extent, spemidine accumulate in both roots and shoots of peas in response to potas stum deficiency and ammomnium supply. Free putrescine responds more sensitively than total putreseine to variatioin of nutrients. Accumulation of putrescine is more pronounced in the roots than in the shoots.
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  • 8
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Inorganic chemistry 14 (1975), S. 473-477 
    ISSN: 1520-510X
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1520-5126
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
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  • 10
    ISSN: 1573-5036
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Plants ofPisum sativum grown in water culture were subjected to deficiencies in the macronutrients N, P, K, S, Ca, Mg, substitution of ammonium for nitrate and change in pH to pH 3 or 9. Free amino acids, soluble nitrogen, protein and glutamate dehydrogenase activity of shoots were measured for all nutrient types. Changes in amino acid concentrations correlated well with changes in glutamate dehydrogenase. It is considered whether this enzyme is indicative of the nutritional state of plants.
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