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1.
M Egger E Donath P Spangenberg M Bimmler R Glaser U Till 《Biochimica et biophysica acta》1988,972(3):265-276
Electrorotation of single platelets was compared with [14C]serotonin release, aggregation and electron microscopy. Activation of washed and degranulated platelets was induced by thrombin, arachidonic acid, collagen, adrenaline, platelet activation factor (PAF), ADP and A23187. A strong correlation between electrorotation decrease and serotonin release was found. Electrorotation did not correlate with aggregation. It was concluded that an increase of the specific conductivity of the platelet membrane by three orders of magnitude (approx. 1.0.10(-7) S.m-1 to 1.0.10(-4) S.m-1) upon activation was responsible for the observed decrease of anti-field rotation and the shift of the first characteristic frequency towards higher values. Electrorotation allowed for time-dependent measurements of activation. Characteristic activation times in the order of minutes were found. There was the following sequence of activators classified by increasing activation time constants: A23187 was the fastest followed by thrombin, collagen, PAF, arachidonic acid, adrenaline, and ADP. 相似文献
2.
Microculture of single protoplasts of Brassica napus 总被引:1,自引:0,他引:1
Protoplasts of Brassica napus L. were cultured individually in a microdroplet system using a synthetic medium with survival rates of more than 70% and division frequencies of up to 65%. Microcallus formation occurred at frequencies of up to 50%. Factors affecting the survival and division of individually cultured protoplasts, such as composition and volume of culture medium, pH, buffering system, osmolarity and genotype, were analyzed. 相似文献
3.
The phagocytic activity of blood granulocytes can be quantitatively assayed by ingestion of opsonised paraffin oil droplets containing the dye Oil Red-O (Stossel, T. P., Mason, R. J., Hartwig, J., and Vaughan, M. (1972)J. Clin. Invest.
51:615–624). We have modified this assay by incorporating [3H]glycerol into the oil droplets which allows a more sensitive and reproducible measurement of the phagocytic competence of blood granulocytes even at very low cell counts. Comparative studies after one day storage of the blood at 4°C is feasible since they retain 84 % of the phagocytic capacity measured when isolated from fresh blood. 相似文献
4.
Summary The biochemical defect in Bloom's syndrome (BS) remains unknown, but two characteristic features of BS cells point to a disturbance of DNA replication, namely, an excessive number of sister-chromatid exchanges (SCEs) in bromodeoxyuridine (BrdU)-substibuted cells and an abnormally slow rate of replicon elongation. The hypothesis of an abnormal DNA polymerase as the explanation for these observations was tested using an in situ assay system for DNA polymerase activity and to estimate molecular weights in cellular extracts of cultured BS cells. DNA polymerase subunits in cellular extracts from the BS cells when separated electrophoretically on polyacrylamide gels showed the same mobilities (i.e., molecular weights) as the controls and were equally effective at promoting the incorporation of isotopically labeled nucleosides. It is concluded that the genetic defect in BS has no direct effect on either DNA-polymerase activity or the amounts and molecular weights of the different forms of the enzyme. 相似文献
5.
Bloom's syndrome. III. Analysis of the chromosome aberration characteristic of this disorder 总被引:14,自引:0,他引:14
The following hypothesis is put forward: X chromatin in man condenses around a center which is situated on Xq at a short distance from the centromere. The hypothesis is based on, and explains, two classes of observations. (1) Abnormal X chromosomes that have the assumed center in duplicate form bipartite Barr bodies in part of the cells. The frequency of bipartite bodies and the distance between the two parts seem to be determined by the distance between the postulated centers. (2) A large number of variously abnormal X chromosomes have been described. Almost all of them possess the postulated center and it seems possible that the very few apparent exceptions represent misidentifications of chromosome Xq — as isochromosome i(Xp). According to the hypothesis, chromosomes lacking the center would form no Barr body and therefore presumably would not be inactivated, thus leaving the cell severely unbalanced. Furthermore, absence of the center might interfere with the viability of the chromosome itself. 相似文献
6.
Plant transformation by microinjection techniques 总被引:4,自引:0,他引:4
Several techniques have been developed for introducing cloned genes into plant cells. Vectorless delivery systems such as PEG-mediated direct DNA uptake (e.g. Pasz-kowski et al. 1984), electroporation (e.g. Shillito et al. 1985), and fusion of protoplasts with liposomes (Deshayes et al. 1985) are routinely used in many experiments (see several chapters of this issue). A wide range of plant species, dicotyledonous as well as monocotyledonous, has been transformed by these vectorless DNA transfer systems. However, the availability of an efficient protoplast regeneration system is a prerequisite for the application of these techniques. For cells with intact cell walls and tissue explants the biological delivery system of virulent Agrobacterium species has been routinely used (for review see Fraley et al. 1986). However, the host range of Agrobacterium restricts the plant species, which can be transformed using this vector system. In addition, all these methods depend on selection systems for recovery of transformants. Therefore a selection system has to be established first for plant species to be transformed. The microinjection technique is a direct physical approach, and therefore host-range independent, for introducing substances under microscopical control into defined cells without damaging them. These two facts differentiate this technique from other physical approaches, such as biolistic transformation and macroinjection (see chapters in this issue). In these other techniques, damaging of cells and random manipulation of cells without optical control cannot be avoided so far. In recent years microinjection technology found its application in plant sciences, whereas this technique has earlier been well established for transformation of animal tissue culture cells (Capecchi 1980) and the production of transgenic animals (Brin-ster et al. 1981, Rusconi and Schaffner 1981). Furthermore, different parameters affecting the DNA transfer via microinjection, such as the nature of microinjected DNA, and cell cycle stage, etc, have been investigated extensively in animal cells (Folger et al. 1982, Wong and Capecchi 1985), while analogous experiments on plant cells are still lacking. 相似文献
7.
With the aid of the Aurelia metamorphosis test system, the acute and subtle developmental and behavioral effects of X irradiation in the presence and absence of thyroxine on the Norfolk Aurelia aurita were described. Radiation doses were 0 (control), 50, 100, 150, 200, and 400 Gy. Morphology of the ephyrae, and statolith and rhopalia numbers were recorded using the light microscope. Developmental abnormalities of the polyps and ephyrae were recorded with the scanning electron microscope and light microscope. Major findings from this investigation were the absence of rhopalia and statoliths in ephyrae at 150 and 200 Gy, a reduction in pulses per minute in the ephyrae at 100, 150, and 200 Gy, a reduction in ephyrae released at 150, 200, and 400 Gy, and the development of polyp monsters. There was a significantly higher frequency of polyp monsters in the group exposed to thyroxine prior to radiation than in the thyroxine-free group prior to radiation. 相似文献
8.
R. Z. German D. W. Hertweck J. E. Sirianni D. R. Swindler 《American journal of physical anthropology》1994,93(3):373-380
Somatic growth is not a simple linear process with a constant rate of growth. The most successful attempts to quantify growth as a function of age or size have employed nonlinear techniques. Sexual dimorphism of primate growth, weight vs. age, was examined using nonlinear models with Sirianni and Swindler's ([1985] Growth and Development of the Pigtailed Macaque, Boca Raton, FL: CRC Press) growth data on the pigtailed macaque (Macaca nemestrina). The best fit of several exponential growth models was the Gompertz curve: Different multiple phase models were also fit, where each phase represents a distinct exponential component. The two-phase models proved to be the best (R2 = .0.84 for females, 0.91 for males), suggesting that there are two growth spurts, one in infancy and one at puberty. The timing of the beginning and end of the first spurt is the same in males and females, but the rate, and value of the asymptote for this phase, is greater in males. The timing of the second spurt is earlier, and the rate of growth for this spurt is smaller in females than males. The sexual dimorphism in these species is not a simple rate change, but a complex interaction of timing and rate over the entire period of growth. It would be impossible to separate these entities with a linear, polynomial, or single-phase model of the data. While these data and results complement much of the existing work on adult dimorphism, they also emphasize the vital role that ontogenetic data have in elucidating the underlying evolutionary mechanisms that generate sexual dimorphism. © 1994 Wiley-Liss, Inc. 相似文献
9.
Linkage disequilibrium between the FES, D15S127, and BLM loci in Ashkenazi Jews with Bloom syndrome. 总被引:4,自引:4,他引:0 下载免费PDF全文
N. A. Ellis A. M. Roe J. Kozloski M. Proytcheva C. Falk J. German 《American journal of human genetics》1994,55(3):453-460
Bloom syndrome (BS) is more common in the Ashkenazi Jewish than in any other population. Approximately 1 in 110 Ashkenazi Jews carries blm, the BS mutation. The locus mutated in BS, BLM, maps to chromosome subband 15q26.1, tightly linked to the proto-oncogene FES. We have investigated the basis for the increased frequency of blm in the Ashkenazim by genotyping polymorphic microsatellite loci tightly linked to BLM in affected and unaffected individuals from Ashkenazi Jewish and non-Ashkenazi populations. A striking association of the C3 allele at FES with blm (delta = .422; p = 5.52 x 10(-7)) and of the 145-bp and 147-bp alleles at D15S127 with blm (delta = .392 and delta = .483, respectively; p = 2.8 x 10(-5) and p = 5.4 x 10(-7), respectively) was detected in Ashkenazi Jews with BS. This linkage disequilibrium constitutes strong support for a founder-effect hypothesis: the chromosome in the hypothetical founder who carried blm also carried the C3 allele at FES and either the 145-bp or the 147-bp allele at D15S127. 相似文献
10.
Thomas L. German Scott Adkins Andy Witherell Kathryn E. Richmond William R. Knaack David K. Willis 《Plant Molecular Biology Reporter》1995,13(2):110-117
Mechanical inoculation ofArabidopsis thaliana ecotype Columbia with tomato spotted wilt virus led to viral replication and spread as determined by dot blot and ELISA analysis.
Severe symptoms were observed three to four weeks post-inoculation. Early symptoms were manifested as chlorotic spots on uninoculated
leaves. Later in the infection process, some plants showed complete chlorosis and wilting prior to bolting. Bolts that were
developed by infected plants were chlorotic and deformed. These preliminary results suggest thatA. thaliana could become a model system for the genetic analysis of host factors required for the replication of viruses in the family
Bunyaviridae, which includes viruses that cause important diseases of both plants and animals. 相似文献