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  • 1
    ISSN: 1432-119X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The production of affinity column purified (specific) anti-actin is described. With the immunization scheme employed, all rabbits produced precipitating antibodies over several months, so that 30 mg specific anti-actin per rabbit could be isolated in 6 months. The antibodies against native and detergent denatured smooth muscle actin are characterized by immunodiffusion tests, staining of the I-band of isolated myofibrils and stress fibers in tissue culture cells, using indirect immunofluorescence.
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  • 2
    ISSN: 1432-119X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Cellular cation was localized with K-pyroantimonate osmium fixation in whole fetal mouse metatarsal bones and in deliberately mechanically damaged specimens. X-ray microprobe analysis of ultrathin sections showed a positive correlation between the concentration of Ca (and Sb) and the amount of electron-dense precipitate. In non-damaged osteoblasts and growth-plate chondrocytes dense precipitate had accumulated along the plasmalemma and the mitochondrial membranes, whereas damaged cells showed the precipitate on round granules in the mitochondrial matrix but not on membranes. Intermediate stages between these two patterns were also found. In a non-calcifying tissue such as liver no membrane-bound precipitate was found in intact cells. However, damaged liver cells showed precipitate-containing mitochondrial granules similar to those in damaged bone cells, but only after incubation of the damaged tissue for l h in a Ca-containing balanced salt solution. Freezing of fresh whole bones in liquid N2 before fixation in K-pyroantimonate osmium did not change the precipitate pattern in the damaged cells, but in intact cells it produced a random distribution of precipitate unrelated to membranes. The results are compared with those obtained in other studies on the subcellular localization of calcium and in biochemical studies on membrane versus matrix loading in calcium-accumulating isolated mitochondria.
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Biological cybernetics 26 (1977), S. 131-139 
    ISSN: 1432-0770
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Computer Science , Physics
    Notes: Abstract A night sleep polygraphic recording was coded by 20 s epochs, taking into account the recognizible features, summarized into 24 variables. In a 24 dimension space, the values of these variables are the coordinates of a point representative of each 20 s epoch. The coordinates of these points are given by a 24 column data table to which a factor analysis is applied in order to provide a bidimensional representation of the electrophysiological phenomena's evolution in time. Such a representation of the possible combinations of variables illustrates the structure of sleep without any biased ideas about this structure. The results obtained make it possible to consider the classical division of sleep into cycles and stages. Sleep seems to evolve continuously in time between a certain number of typical combinations, which supports the concept of cycle, but never following the same evolution between these combinations, which questions the reality of stages and their similarity from one cycle to the other. The method described seems to reflect more accurately than the classical hypnogram the phenomena of continuous modulation of nervous activity during sleep, and to open interesting possibilities for an analytical automatic treatment of sleep electrophysiological signals.
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  • 4
    ISSN: 1432-0827
    Keywords: Cellular calcium ; Electron microscopy ; Osteoblasts ; Chondrocytes ; Mineralization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary The calcium distribution in cartilage and bone cells during beginning ossification of fetal mouse long bones was studied after fixation with 2% K-pyroantimonate in 1% osmium. In the developing periosteum, the future osteoblasts showed a sparse cation-antimonate precipitate over the cytoplasm. In young osteoblasts the precipitate was accumulated on the mitochondrial membranes and the plasmalemma. Both organelles were sharply outlined by precipitate in the mature osteoblasts at the onset of mineralization. X-Ray microprobe analysis of these organelles demonstrated the presence of both Sb and Ca. In the extracellular compartment, a collagen-associated precipitate with 50 to 60 nm periodicity appeared during osteoblastic differentiation. During the initial phase of matrix mineralization, a random gross precipitate appeared in the matrix and seemed to be accumulated by osmiophilic matrix vesicles while the collagen fibrils lost their precipitate. Subsequently, during the confluent phase of matrix mineralization, the precipitate rapidly disappeared from the cells, leaving them devoid of precipitate once they were surrounded by mineralized matrix. Similar changes were found in the chondrocytes of the growth plate, but cartilage collagen, unlike osteoid collagen, did not bind precipitate. The results indicate that both osteoblasts and calcifying cartilage cells bind calcium prior to matrix mineralization. Bone collagen has strong pyroantimonate binding capacity, but it is not directly involved with initial stages of matrix mineralization, which starts in close association with matrix vesicles.
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  • 5
    ISSN: 1434-6036
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract High purity argon polycrystals were doped with 0.2 ppm of K41 through the nuclear reaction Ar40(n, β −)K41. Optical transmission was measured as a function of the annealing temperature between 300 nm and 800 nm. Absorption bands corresponding to the transitions 42 p 1/2, 3/2←42 s 1/2 and 52 p 1/2, 3/2←42 s 1/2 of free potassium atoms could be observed. Annealing dependence of these absorption bands was studied and may be understood by a simple model.
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  • 6
    ISSN: 1617-4623
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary In crosses of [ANT R8] with auxotrophic strains, resistance to antimycin segregates almost 50:50 in random spore analysis with a slight preponderance for the sensitivity allele. Tetrad analysis, however, shows all possible types of tetrads (2:2; 3:1; 1:3; 4:0; 0:4 resistant versus sensitive) with an excess of 2:2 segregations and sectoring of colonies on antimycin medium indicating an extrachromosomal mode of inheritance. The overall ratio of resistant versus sensitive spores is the same as compared with random spore data. Using a mutant blocked in meiosis (mei 1) mitotic segregation of stable diploids is achieved, leading to a ratio of 20% resistant to 80% sensitive clones. Possible reasons for the bias in transmission of the resistance determinant are discussed. Mitotic haploidization experiments reveal no linkage of the [ANT R8] mutational site to markers on any of the three on to now known chromosomes and disagrees so far with the possibility of a nuclear mutation necessary for expression of the extrachromosomal mutation. Growing the mutant [ANT R8] and/or the wildtype in the presence of ethidium bromide (EB) before mating, one can change the ratio of resistant versus sensitive diploids, indicating a multiple number of resistance determinants. The sum of all results makes it very likely that [ANT R8] is a mitochondrial mutation. In addition, the paper presents the methodology for extrachromosomal genetics in Schizosaccharomyces pombe.
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  • 7
    ISSN: 1617-4623
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary 1. A mutant (ANT 8) ofSchizosaccharomyces pombe which shows resistance to antimycin bothin vivo andin vitro is characterized biochemically and genetically. 2. In crosses of ANT 8 with auxotrophic strains, resistance to antimycin segregates 2:2 indicating that resistance is conferred by a single nuclear gene. Diploids heterozygous for the resistance gene, however, show segregation of the resistance and sensitivity during mitosis. Possible reasons for this segregation are discussed. 3. Compared with the wild type, the NADH oxidase of ANT 8 requires 13 times as much antimycin for 95% inhibition. After addition of ubiquinone-3, electron transport which is less sensitive to antimycin is found only in the mutant. 4. The resistance of the mutant ANT 8 is due to the much weaker binding of antimycin to mitochondria. As in the wild type, two antimycin binding sites can be separated by binding studies. From the inhibition curves it is evident that binding of antimycin to oxidized mitochondrial particles does not correspond with its inhibitory effect on the partly reduced enzyme in kinetic studies. 5. The peak of theb-cytochrome absorbing at 560.2 nm at 77° K in the wild type is shifted to 561 nm in the mutant. 6. A special preparation method for mutant mitochondrial particles is described, yielding highly active enzymes and CO-insensitive cytochromes. 7. The results are discussed with reference to the components in our model of the respiratory chain, which may be responsible for this type of resistance.
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  • 8
    ISSN: 1615-6110
    Keywords: Vicia narbonensis ; V. sativa. ; Ribosomal RNA ; secondary constriction ; in situ hybridization ; Feulgen staining ; karyogram
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Sites of 18/25S RNA genes and those of secondary constrictions have been located in metaphase chromosomes ofV. narbonensis andV. sativa by RNA/DNA in situ hybridization and Feulgen staining. InV. narbonensis the rRNA genes are located in median position on one pair of chromosomes, which is the shortest of all in the genome. InV. sativa rRNA genes are located in two pairs of chromosomes. The two heterologous sites differ markedly in the level of labeling. Strong labeling is found in a submedian position of a short pair of chromosomes. Weaker labeling is found in a median position on the longest pair of chromosomes. InV. narbonensis andV. sativa the position of the grain clusters correlate with the position of the secondary constrictions in chromosomes stained by Feulgen. The implications with respect to karyograms ofV. narbonensis andV. sativa known from the literature are discussed.
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  • 9
    ISSN: 1617-4623
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary In contrast to the wild-type, mutant [ANT R8] is able spontaneously to throw off stable respiratory deficient mutants. The frequency of these mutants is considerably enhanced by treatment with ethidium bromide (EB) or the azo-dye Janus green (JG). An unstable cell state with a petite-like phenotype is found in both mutant [ANT R8] and wild-type after EB-treatment. However, only in the mutant is this unstable cell state followed by the appearance of stable respiratory deficient (RD) mutants. Formation of microcolonies is observed both in [ANT R8] and wild-type. RD mutants were isolated after EB treatment. Three of them (mit-12, mit-25, and mit-30) were analyzed and mit-25 characterized in more detail. Mutant mit-25 shows mitotic segregation in the diploid state, indicating non-Mendelian mode of inheritance. The results of haploidization experiments also indicate extrachromosomal inheritance. Mit-25 shows a spontaneous rate of reversion of 10-6, which can considerably increased by EB. Mit-25 possesses enzymatically active complexes I, II, and III of the respiratory chain (the latter without cytochrome b-566), lacks complex IV and binds antimycin, showing that mitochondrial protein synthesis is functional. Several lines of evidence presented in this paper make it very likely that the lesion in the mutant mit-25 is a point mutation in mitochondrial DNA.
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Molecular genetics and genomics 166 (1978), S. 277-285 
    ISSN: 1617-4623
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Specific labelling of replicating bacteriophage SPP1 DNA can be achieved by infection at nonpermissive temperature of a B. subtilis strain carrying the initation mutation dnaB ts134. Under these conditions host DNA synthesis is reduced by 90 to 95%. This technique was used to identify cistrons of SPP1 involved in phage DNA synthesis and to define intermediates in SPP1 replication.
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