摘要:

We studied the behaviour in interphase and mitotic human cells of a 125 kDa (pI 6.5) antigen, associated with the nuclear matrix and detected in proliferating cells. Indirect immunofluorescence with a specific monoclonal antibody reveals that during interphase in WISH and Namalwa cells, as well as phytohaemagglutinin—stimulated lymphocytes, the antigen displays a speckled distribution in the nucleoplasm of all cells. At early prophase the fluorescence intensity of the coalesced speckles increases markedly. During metaphase and anaphase the antigen gives maximal fluorescence distributed diffusely in the nucleoplasm, while chromosomes remain negative. At anaphase and cytokinesis the antigen is still cytoplasmic, but fluorescence intensity decreases. Two‐dimensional gel electrophoresis and immunoblotting reveal that the p125/6.5 antigen displays a net increase in isolated mitotic cells as compared to interphase cells. These results suggest that the p125/6.5 protein participates in late G2 phase and G2/M transition events preparing the cell for mito

ISSN:0248-4900    

DOI:10.1111/j.1768-322X.1988.tb00711.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

The analysis of ultrathin serial sections as 3‐dimensional (3D) information requires interpretation and display of a large amount of data. We suggest a simple way to solve this problem; it permits presentation of a series of sections as a 3D color image of good quality. It involves a picture system with specialized hardware and software written for this purpose.3D images of cellular organelles have been drawn either by manually defining the contour of the objects or by thresholding of the volumes in the structures.These 2 methods allow rapid drawing of the image on the screen. It is possible to determine the position, shape and size of 3D structures. This interactive system allows the user to choose between several option: colors, removal of parts of the object, and cutou

ISSN:0248-4900    

DOI:10.1111/j.1768-322X.1988.tb00712.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

Irradiation under anoxic conditions with near‐UV light (300–400 nm walength) ofAllium cepaL. root meristems whose cycling cells have their DNA bromosubstituted brings about accumulation of cells in both G1and G2stages, in frequencies similar to those found in dormant roots. On the other hand, cells in mitosis nearly disappear from the 12th hour onwards after light irradiation. Since fidelity of transcription is lost after such treatment, the data suggest that altering the pattern of gene expression in the cell cycle is a way to achieve dormancy in these previously proliferating merist

ISSN:0248-4900    

DOI:10.1111/j.1768-322X.1988.tb00713.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

In a previous work it was shown that transferrin (Tf) secretion is directly related to the membrane surface area of hepatocytes (Péchinot D.et al.[31]). The aim of the present work was to search for a possible relationship between Tf secretion and hepatocytic ploidy using a semi‐automatic image analysis method. A determination of Tf secretion by isolated normal adult hepatocytes was achieved at the single cell level, using a modified reverse hemolytic plaque test. A Feulgen reaction was also performed on these hepatocytes. It allowed the evaluation, for each secreting hepatocyte, of the quantity of Tf secreted and its nuclear characteristics. Discrimination between diploid (2c) and tetraploid (4c and 2c2c) hepatocytes was performed and the amount of Tf secreted by each subpopulation determined. It appeared that a 2‐fold secretion ratio was not found between tetraploid and diploid hepatocytes. These results suggest, as Tf production is not directly proportional to the degree of ploidy of hepatocytes, that some not yet elucidated regulatory mechanisms may act on Tf gene expres

ISSN:0248-4900    

DOI:10.1111/j.1768-322X.1988.tb00714.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

The organization of tight junctional complexes (TJs) was studied in cultured porcine thyroid cells during the inversion of polarity induced by collagen‐embedding of inside‐out follicles, using freeze‐fracture replicas and lanthanum penetration. During the early steps of polarity reversal, freeze‐fractures showed that TJs generally persisted. They increased in width and progressively branched out into the basolateral surfaces, towards the basal pole. Later, the number of TJ strands decreased and gap junctions inserted within TJ networks were found between cells in reversed follicles, in the same manner as in typically polarized follicles, embedded in collagen or in suspension. Thede novoformation of TJ complexes was rarely found in the reversing structures. Despite the heterogeneity of TJs assessed by freeze‐fracture, impermeability to lanthanum tracer was noted in inside‐out structures. During the reversal process, some TJs remained unstained, whereas others displayed permeability to lanthanum. This heterogeneity might be due to the ≪opening≫ of a small number of junctions (perhaps only one by aggregate). When the process was achieved after 48 hr in collagen, the tightness of the junctions was complete, confirmed by the absence of lanthanum in luminal cavities of newly f

ISSN:0248-4900    

DOI:10.1111/j.1768-322X.1988.tb00715.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

The analytical ion microscope (AIM) makes possible imaging and relative quantitation of multiple stable or labeled elements on an even tissue section, according to their mass. The purpose of this work was to follow at the rat thyroid follicle level the changes in127I mapping during low iodine diet (LID) in relation to the ability of thyroid to pick up radioiodine (129I) and to synthesize Tg from its precursor,2H‐labeled leucine. The overall picture of images and countings of127I shows a progressive decrease of the luminal iodine concentration which on day 80 was 10‐fold lower than that of control value. In control rat thyroid cell, concentration was 10‐fold lower than that of follicular lumina and was unchanged until 35 days, but the size of the cytoplasmic compartment increased, suggesting a redistribution of iodine stores between thyroid cells and follicular lumina.129I was always found in colloid as well as in cells at all stages. After 35 days of LID, cytoplasmic and luminal radioiodine concentrations decreased. In control rats, [2H]leucine was found mainly in the cells. During LID its localization was evidenced progressively in most of the lumina. The most striking fact was the presence up to 35 days of some large residual follicles with high127I concentration and low129I and2H incorporation. These data demonstrate the follicular heterogeneity of thyroid response to progressive chronic TSH stimulation induced b

ISSN:0248-4900    

DOI:10.1111/j.1768-322X.1988.tb00716.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

The serum of a patient suffering from myeloma was found to decorate microtubules and mitotic spindles of cultured cells. Immunoblots performed after one‐ and two‐dimensional electrophoresis showed a reaction with a certain subset of β‐tubulin isoforms, but not with β′‐ and α‐tubulins. The tubulin subset contained both ubiquitous (β‐3) and neurospecific (β‐4,5,6) isoforms.An IgM lambda and an IgA kappa myeloma protein were found in this serum. Immunoblots performed with specific anti‐isotype second antibodies showed that the tubulin subset could be evidenced using anti‐mu, alpha, lambda, and kappa‐specific antisera. Moreover, the tubulin subset was also evidenced using an anti‐gamma second antibody. These results, which do not exclude a participation of the myeloma proteins in the anti‐tubulin reactivity, indicate, however, that the antibody response was polyclonal. The same restricted specificity of all classes of anti‐tubulin antibodies of this serum favours the hypothesis that the immune response of the patient was directed against an antigen sharing epitopes with tubulin

ISSN:0248-4900    

DOI:10.1111/j.1768-322X.1988.tb00717.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

Serial ultrathin sections were used to study the formation of the primary cilium and the centriolar apparatus, basal body, and centriole in the neuroepithelial primordial cell of the embryonic nervous system in the mouse. At the end of mitosis, the centrioles seem to migrate toward the ventricular process of the neuroepithelial cell, near the ventricular surface. One of these centrioles, the nearest to the ventricular surface, begins to mature to form a basal body, since its tip is capped by a vesicle probably originating in the cytoplasm. This vesicle fuses with the plasmalemma and the cilium growth by the centrifugal extension of the 9 sets of microtubule doublets. These 9 sets invade the thick base of the cilium which is initially capped by a ball‐shaped tip with the appearance of a mushroom cilium. The secondary extension of 7, then 5, and finally 2 sets of microtubule doublets contribute to form the tip of the mature cilium, which is associated with a mature centriolar apparatus formed by a basal body and a centriole. Centriologenesis occurs before mitosis and is concomitant with the progressive resorption of the cilium. The daughter centriole, or procentriole, begins to take form near the tips of fibrils that extend perpendicularly and at a short distance from the wall of the parent centriole. Osmiophilic material accumulates around these fibrils, and gives rise to the microtubules of the mature daughter centriole. These centrioles formed by a centriolar process are further engaged in mitosis, after the total resorption of the cilium. This pattern of development suggests that in the primordial cells of the embryonic nervous system, centriologenesis and ciliogenesis are 2 independent phenomen

ISSN:0248-4900    

DOI:10.1111/j.1768-322X.1988.tb00718.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

Regeneration of several adult rat and mouse skeletal muscles was studied after degeneration of muscle fibers had been obtained by the selective action of the cardiotoxin ofNaja mossambica mossambicavenom. Experimental conditions were set up to ensure minimal damage to satellite cells and also the nerves and blood vessels of the original muscles. As in the other types of experimental regeneration, the structure of the regenerated muscle appeared in many respects different from that of the normal muscle. Moreover the neuromuscular junctions of ‘en plaque’ type were transformed to ‘en grappe’ type junctions. May ultrastructural abnormalities often displayed by these junctions might be linked, at least partially, to the persistence in the regenerating muscle of the original synaptic basal lamina sheaths and their inductive pro

ISSN:0248-4900    

DOI:10.1111/j.1768-322X.1988.tb00719.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

Primary cultures of mesenchymal cells of axolotl limb blastemas provide a very sensitivein vitrobioassay for studying nerve dependence of newt regeneration. These cells can be stimulated by crude spinal cord extracts on non‐amputated animals in a dose‐dependent manner up to 60 μg protein/ml of culture medium; at this concentration the mitotic index is increased 4‐fold. Spinal cord extracts of axolotls 14 days after forelimb amputation (i.e., late bud stage) are more efficient in stimulating blastema cell proliferation (+50%) than extracts of axolotls 7 days after forelimb amputation (i.e., early bud stage) or of axolotls without amputation. In a similar manner, spinal cord extracts of young axolotls 14 days after forelimb amputation, are more stimulatory than older axolotls 14 d after forelimb amputation which regenerate only a very small blastema during the same time. It appears that spinal cord mitogenic activity is enhanced after limb amputation, probably in correlation with blastema cell requirements for limb regene

ISSN:0248-4900    

DOI:10.1111/j.1768-322X.1988.tb00720.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY