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D Ploton

Publications and source records attributed to D Ploton.

48 records · Page 3Linked to original sources
PubMed1987

Behaviour of nucleolus during mitosis. A comparative ultrastructural study of various cancerous cell lines using the Ag-NOR staining procedure.

The aim of the present work was to study the distribution and the behaviour of the silver-staining nucleolar organizer region (Ag-NOR) proteins at the ultrastructural level during interphase and mitosis in five human and murine cancerous cell lines each characterized by a typical nucleolar morphology. During interphase the Ag-NOR proteins are restricted to the fibrillar centres (F.C.) and/or to the dense fibrillar component (D.F.C.). During prophase the silver-staining components come into close contact with some chromosomes and are arranged with a typical polarity: chromosome, F.C. and D.F.C. Then F.C. and D.F.C. together form roundish silver-stained structures and integrate in part within indentations at the periphery of the metaphase chromosomes. During anaphase and telophase large and small spherical silver-staining structures may be seen. They correspond respectively to the metaphase NORs and to numerous structures which appear de novo within ribonucleoprotein (RNP) material localized between the chromosomes. During late telophase the number of the small silver-staining structures decreases whereas the size of the larger ones increases. Then the interphase nucleoli recover their typical shape. These results suggest that when rRNA synthesis is impaired during mitosis the inactive NORs assume a structure and a localization which are not typical of the cell line. In contrast the F.C. and D.F.C. are probably two aspects of the NORs whose typical distribution, relative to the other nucleolar components, gives the interphasic nucleolus its characteristic morphology.

Anaphase↗
PubMed1987

The three-dimensional ultrastructure of interphasic and metaphasic nucleolar argyrophilic components studied with high-voltage electron microscopy in thick sections.

The three-dimensional structure of the nucleolar argyrophilic components was studied by recording stereo-pairs of tilted thick sections--0.5-2 microns thick--observed with 200 and 300 kV high-voltage electron microscopy (HVEM). Using a very specific silver staining method, the argyrophilic components were stained with a high contrast relatively to the unstained background, thus allowing their study with a high resolution within thick sections. This study was performed on compact nucleoli (of HL60 and K562 cells), on reticulated nucleoli (of human breast cancerous cells) and on metaphasic nucleolar organizer regions (NORs). In compact nucleoli argyrophilic components show a 'knotted rope-like' structure in which knots are constituted of one central fibrillar centre surrounded at some distance by loops of the dense fibrillar component and in which the rope is constituted of dense fibrillar component. In reticulated nucleoli silver deposits are confined to the surface of the nucleolonema as several strands twisted at the periphery of the fibrillar component. During metaphase some NORs get a characteristic crescent-shaped structure disposed at the periphery of some chromosomes.

Breast Neoplasms↗
PubMed1986

Improvement in the staining and in the visualization of the argyrophilic proteins of the nucleolar organizer region at the optical level.

The argyrophilic proteins of the nucleolar organizer region (Ag-NOR proteins) were specifically localized at the optical level with a modified one-step silver technique performed at 20 degrees C. This method was applied to various materials including cells in smears, chromosomes, semi-thin sections of plastic-embedded cells and sections of paraffin-embedded human pathological tissues. In order to improve the visualization of the silver deposits we tested various modes of imaging, including bright-field, Nomarski contrast, reflected light and combined Nomarski contrast with reflected light. The use of Nomarski contrast is useful to define precisely the phases of mitosis. The use of reflected light, which is based on the ability of silver to reflect incident light specifically, gives images with an improved resolution compared to bright-field.

Cell Line↗
PubMed1985

Simultaneous ultrastructural localization of Ag-NOR (nucleolar organizer region) proteins and ribonucleoproteins during mitosis, in human breast cancerous tissues.

The simultaneous ultrastructural localization of the Ag-NOR proteins and ribonucleoproteins (RNP) was carried out during mitosis in human breast cancerous tissues using a one-step silver staining method followed by acetylation. Owing to the good preservation of the cells and to the high precision of the Ag staining we were able to follow the behaviour of the argyrophilic nucleolar components from prophase to late telophase. During all the phases of mitosis the Ag-NOR proteins were associated with fibrillar RNP component (without visible fibrillar centre), which originated, during prophase, from the dense fibrillar component of the nucleolus and then integrated within the periphery of some metaphasic chromosomes as irregular structures. The Ag staining of these structures was homogeneous but lower compared to those of nucleoli during prophase. The RNP sheath that covered the chromosomes was never silver stained. From anaphase to early telophase the argyrophilic RNP structures disposed within the periphery of the chromatin mass formed roundish and then spherical structures in which the Ag-NOR proteins were clustered as centrally localized spheres. These findings showed the usefulness of our method for the precise study of the spatial relationship between the Ag-NOR proteins and the chromosomes. Thus we were able to show striking segregation of both the argyrophilic structures at the periphery of the chromatin mass and of the Ag-NOR proteins within these structures. This suggests that a high degree of the structural organization in the future nucleus is already present during anaphase. This could be related to the rapid resumption of ribosomal RNA synthesis.

Acetylation↗
PubMed1984

Simultaneous high resolution localization of Ag-NOR proteins and nucleoproteins in interphasic and mitotic nuclei.

Silver stainable proteins of the Nucleolar Organizer Regions (Ag-NOR proteins) of human breast cancer tissues have been localized at the electron microscopical level with a new method which combines a simple and reproducible one step Ag-NOR staining method combined with an acetylation procedure. This new method allows the fine identification of nucleolar components, particularly those which are stained by silver. In order to determine the cytochemical nature of the components associated with Ag-NOR proteins, the EDTA regressive preferential staining procedure for ribonucleoproteins has been applied to sections. By this means the precise localization of the Ag-NOR proteins was studied simultaneously with that of ribonucleoprotein within interphasic nucleoli and mitotic chromosomes. In interphasic nucleoli, stainable Ag-NOR proteins were localized in fibrillar centres and part of the dense fibrillar component. No silver deposits were seen on perichromatin or interchromatin fibrils and granules. In metaphasic nuclei, Ag-NOR proteins were only found on roundish fibrillar ribonucleoprotein structures, which could correspond to secondary constrictions. No silver deposits were seen on the well defined ribonucleoprotein sheet surrounding the chromosomes. In telophasic nuclei, Ag-NOR proteins were seen on the central part of roundish ribonucleoprotein fibrillar structures integrated in decondensing chromosomes. These structures have been interpreted as the nucleolar organizer regions around which rRNA synthesis resumes. In interphasic and mitotic nuclei, Ag-NOR proteins were never found within condensed chromatin but always in association with ribonucleoprotein components. The new method proposed here appears to be a useful tool for the simultaneous study of the localization of ribonucleoprotein and Ag-NOR proteins during the cell cycle.

Acetylation↗
PubMed1983

Ultrastructural localization of Ag-NOR proteins and nucleic acids in reticulated nucleoli.

Nucleoli with a thread-like fibrillar structure found in several human breast cancer cells were investigated for the localization of Ag-NOR proteins, RNA, DNA and associated nucleoproteins. Various cytochemical techniques were applied: the one-step silver method for Ag-NOR proteins, the Bernhard's staining preferential for RNP, the Feulgen-like osmium-ammine reaction for DNA and the RNase- and DNase-gold complexes for the demonstration of RNA and DNA respectively. Staining for Ag-NOR proteins was restricted to the edge of the threads or cords and to the nodes of the nucleolar network. The Bernhard's EDTA technique gave a positive staining of the entire nucleoli and on small peripheral granules which were linked to the nucleolar cords by fine RNP fibrils. Localization of RNA molecules by the RNase-gold complex showed a similar pattern, dense labeling by gold particles over the nucleoli and at the periphery of the cords. DNA molecules were revealed by the osmium-ammine technique in small nucleoplasmic clumps and at the edge of the nucleolar cords. Similar results were obtained by applying the DNase-gold complex which showed a labeling by gold particles over the dispersed chromatin and at the edge of the nucleolar cords. The consistency of the results obtained speaks in favor of their specificity and seems to demonstrate the simultaneous localization of certain Ag-NOR proteins, DNA and RNA molecules at the edge of the nucleolar cords. This edge of nucleolar cords becomes then the candidate for the site of nucleolar transcriptional activity.

Breast Neoplasms↗
PubMed1982

[Colonic nerve network demonstrated by quinacrine].

Quinacrine can be used for fluorescence microscopy to visualize certain cell bodies and fibres in the myenteric plexus of the intestine, forming a network different from the cholinergic and adrenergic systems. In the Piebald mouse, animal model of congenital megacolon, the quinacrine positive plexus is thin in the distal narrowed segment and well developed in the large proximal zone. In Hirschsprung's disease, the quniacrine positive network has the same pathologic features but, contrary to the animal model, there is an increased number and size of extrinsic cholinergic and adrenergic fibres. So this mouse is an animal model of a pseudo-Hirschsprung's disease, which has not yet been reported in human pathology.

Adenosine Triphosphatases↗
PubMed1981

[Renal lesions after irradiation and chemotherapy with adriamycin, vincristin and 5-fluoro-uracil (author's transl)].

After hysterectomy and bilateral annexectomy for bilateral ovarian carcinoma, a 34 years old woman was treated by radiotherapy and chemotherapy associating adriamycin, vincristin and 5-fluoro-uracil. After this treatment, proteinuria and progressive renal failure developed. Renal biopsy showed prominent glomerular lesions with mesangiolysis and some necrotic arteriolar lesions. The role of radiotherapy and chemotherapy in the pathogenesis of these lesions is discussed.

Acute Kidney Injury↗
PubMed1977

[Nucleolar structure during the prophase of Physarum polycephalum].

With Sugihara's fixation technique, electron microscopic study of early-prophase nucleolus in the Physarm polycephalum showed the existence of particular fibrillar structures. The characteristic feature of these spherical structures is an electron-lucid center surrounded by a dense fibrillar component. Their relationships between the "fibrillar centers" and between the rate of ribosomal RNA synthesis are studied.

Animals↗
PubMedDate not supplied

Nucleolar organizer regions in congenital mesoblastic nephroma.

A review of 78 renal tumors in patients under 6 months of age revealed 35 congenital mesoblastic nephromas (CMNs). Based on cellular criteria, 14 were classified as classical, 4 as partly cellular, and 17 as cellular CMN. The mean ages were 24, 11, and 70 days, respectively. There were 13 intrarenal tumors (stage I) but 9 classical, 3 partly cellular, and 5 cellular CMNs extended to the perirenal fat (stage II) and 5 cellular tumors ruptured (stage III). In order to assess cellular proliferative activity, silver staining of nucleolar organizer region (Ag-NOR) proteins was performed on 19 CMNs. The number of Ag-NOR dots per cell was significantly lower in classical and partly cellular CMN than in cellular CMN, whatever the stage (P < .01). Within the cellular CMNs, the mean number of Ag-NOR dots was statistically higher in the single case that recurred with fatal outcome (P < .02). Counting of Ag-NOR dots appears to be a reproducible method for evaluating the biologic potential of CMNs. The number of Ag-NOR dots, DNA content measurements, the histological subclassification, and the presence or absence of tumor at the surgical margins may be useful features in selecting those patients who will benefit from further treatment after nephrectomy.

Female↗