scholarly journals Visualization of nucleolar substructure in cultured human fibroblasts by magnesium-activated adenosine triphosphatase reaction.

1981 ◽  
Vol 29 (10) ◽  
pp. 1115-1120 ◽  
Author(s):  
N Fox ◽  
C Fernandez ◽  
G P Studzinski
Keyword(s):  
Adenosine Triphosphatase ◽  
Divalent Cations ◽  
Human Fibroblasts ◽  
Lead Nitrate ◽  
Nucleolar Organizer ◽  
Nucleolar Organizer Regions ◽  
Electron Microscopic ◽  
Atpase Reaction ◽  
Cultured Human Fibroblasts ◽  
A Minor

Discrete sites of adenosine triphosphatase (ATPase) activity were demonstrated within the nucleoli of unfixed cultured human fibroblasts (IMR90, VA13, and AG2804 cells) by an adaptation, for electron microscopic cyto-chemistry, of Wachstein and Meisel's lead nitrate method. The majority of nucleoli contained more than one ATPase-positive region, but the total ATPase-positive material appeared to occupy only a minor portion of the nucleolar volume. These regions were roughly spherical with an irregular contour, and at times appeared to be components of perinucleolar chromatin or to be located adjacent to nucleolar interstices. The distribution of these regions within the nucleolus and their segregation by actinomycin D suggested that the ATPase-positive regions correspond to the fibrillar centers, which represent nucleolar organizer regions. The cytochemically demonstrable nucleolar ATPase was strictly dependent on the presence of divalent cations. Optimal reactions was seen at 5 mM Mg2+, but near optimal activity was obtained with lower concentrations of Mg2+ in the presence of Ca2+. Calcium alone and Mn2+ alone produced suboptimal reaction. Studies with different nucleoside phosphates as reaction substrates showed that the enzyme is specific for adenosine derivatives, ATP and dATP being equally good substrates. Guanosine triphosphate, cytidine triphosphate, uridine triphosphate, and d-thymidine triphosphate were ineffective as substrates, as were nucleoside mono- and diphosphates and other phosphate esters tested. It is suggested that the cytochemical ATPase reaction visualized the regions of the nucleolus in which ribosomal DNA of intranucleolar chromatin is undergoing conformational alterations.

scholarly journals DNA dependence and inhibition by novobiocin and coumermycin of the nucleolar adenosine triphosphatase (ATPase) of human fibroblasts.

1982 ◽  
Vol 30 (4) ◽  
pp. 364-370 ◽  
Author(s):  
N Fox ◽  
G P Studzinski
Keyword(s):  
Adenosine Triphosphatase ◽  
Elevated Temperatures ◽  
Human Fibroblasts ◽  
Nucleolar Organizer ◽  
Electron Microscopic ◽  
Dna Topoisomerase ◽  
B Subunit ◽  
Electron Microscopic Cytochemistry ◽  
Nucleolar Chromatin ◽  
A Subunit

We have recently demonstrated by electron microscopic cytochemical methods that unfixed human fibroblasts exhibit intense MG2+ dependent adenosine triphosphatase (nATPase) activity in circumscribed areas of the cell nucleoli. The nATPase was specific for ATP and dATP and was inhibited by other ribonucleoside triphosphates. Its intranucleolar localization relative to nucleolar chromatin, and segregation into nucleolar zones after actinomycin treatment of the cells, suggested that the reaction took place in fibrillar centers. This ATPase has now been further characterized by electron microscopic cytochemistry. It was determined that short fixation permitted retention of most of the ATPase activity, and that the enzyme was active at high ionic strength (up to 400 mM KCl), but that the enzyme activity was very sensitive to elevated temperatures. DNA dependence of the enzyme was shown by inhibition of the reaction by DNase pretreatment in parallel with the removal of DNA from the cell, while pretreatment with RNase had no significant effect. The nATPase activity was also selectively inhibited by treatment of the cells with antagonists of the B subunit of DNA gyrase, novobiocin, and coumermycin, but not by nalidixic or oxolinic acids, which interfere with the A subunit of gyrase. Inhibitors of RNA synthesis, actinomycin D and aminonucleoside of puromycin, potentiate rather than inhibit nATPase reaction. The results suggest that nATPase functions to alter the degree of supercoiling or catenation of nucleolar organizer DNA, and is in reality a DNA topoisomerase that hydrolyzes ATP during its action.

Electron Microscopic investigation of crooke’s change in the pituitaries of patients with hypercorticism

1989 ◽  
Vol 47 ◽  
pp. 848-849
Author(s):  
E. Horvath ◽  
K. Kovacs ◽  
L. Stefaneanu ◽  
N. Losinski
Keyword(s):  
Nucleolar Organizer ◽  
Microscopic Investigation ◽  
Electron Microscopic Investigation ◽  
Ectopic Acth Syndrome ◽  
Nucleolar Organizer Regions ◽  
Electron Microscopic ◽  
Human Pituitary ◽  
Ectopic Acth ◽  
Crooke’S Hyalinization

Human pituitary corticotropins have unique morphologic markers: bundles of type-1 filaments, measuring approximately 70 A in width and representing cytokeratin. The extreme ring-like accumulation of type-1 filaments, known as Crooke's hyalinization, signals functional suppression of the corticotropins and occurs in endogenous and exogenous glucocorticoid excess, caused by ACTH-secreting pituitary adenoma, glucocorticoid secreting adrenocortical tumor, ectopic ACTH-syndrome and administration of pharmacologic doses of glucocorticoids. Cells of autonomous corticotroph adenomas usually do not show Crooke's hyalin change. A minority of these tumors, however, retains sensitivity to the negative feed-back effect of elevated blood glucocorticoid levels and display typical Crooke’s change.In the present study pituitary corticotropins in various phases of Crooke's hyalinization were investigated in patients with glucocorticoid excess of various origin, applying histology, immunocytochemistry, count of argyrophilic nucleolar organizer regions (AgNOR), and transmission electron microscopy.

Electron Microscope observations on Mitotic Chromosomes

1965 ◽  
Vol s3-106 (75) ◽  
pp. 197-214
Author(s):  
N. A. BARNICOT ◽  
H. E. HUXLEY
Keyword(s):  
Tissue Culture ◽  
Divalent Cations ◽  
Human Fibroblasts ◽  
Mitotic Chromosomes ◽  
Electron Microscopic ◽  
Mitotic Apparatus ◽  
Monolayer Cultures ◽  
Effects Of Ph ◽  
Heart Cultures ◽  
Mitotic Cells

A method is described by which single mitotic cells growing in tissue culture can be selected under the light microscope and then sectioned for electron-microscopic study. The method has been applied to mitotic cells in newt heart cultures and to monolayer cultures of human fibroblasts. The structure of the chromosomes and of the mitotic apparatus at various phases of mitosis are described and discussed. The effects of pH and of divalent cations on the fixation of chromosomes by buffered osmic mixtures are also considered.

Silver-Stained Nucleolar Organizer Regions in Adenocarcinoma of the Cervix - A light and Electron Microscopic Study

1997 ◽  
Vol 193 (4) ◽  
pp. 275-281 ◽  
Author(s):  
Yasuhiro Yokoyama ◽  
Yuichiro Takahashi ◽  
Dilbaz Serda ◽  
Shigeo Morishita ◽  
Midori Hashimoto ◽  
...  
Keyword(s):  
Microscopic Study ◽  
Electron Microscopic Study ◽  
Nucleolar Organizer ◽  
Nucleolar Organizer Regions ◽  
Electron Microscopic

scholarly journals Electron microscopic studies of silver-strained proteins in nucleolar organizer regions: location in nucleoli of rat sympathetic neurons during light and dark periods

1981 ◽  
Vol 51 (1) ◽  
pp. 85-94
Author(s):  
M.J. Pebusque ◽  
R. Seite
Keyword(s):  
Dark Period ◽  
Sympathetic Neurons ◽  
Nucleolar Organizer ◽  
Fold Increase ◽  
Staining Procedure ◽  
Nucleolar Organizer Regions ◽  
Electron Microscopic ◽  
Main Site ◽  
Fibrillar Component ◽  
Silver Grains

Ag-AS staining of nucleolar organizer regions was carried out on interphasic superior cervical ganglia neurons of rats sacrificed during light and dark periods. While the Ag-AS technique has mostly been used monolayer cell lines or cell suspensions, the present study showed that in electron microscopy this technique is also applicable to small pieces of tissues. The finest pictures are obtained when (I) all solutions used for the staining procedure are at pH 4.5-4.7 and (2) the second step of the reaction involving ammoniacal silver and formalin developing solutions does not exceed 3 min. The results indicate that in the 2 time periods studied, a positive reaction took place exclusively in nucleolar fibrillar centres and in the fibrillar centres and in the fibrillar ribonucleoprotein (RNP) component (dense fibrillar component). The other nucleolar components, i.e. granular and vacuolar, were devoid of silver deposits. As previously shown in sympathetic neurons, the fibrillar centres of the nucleoli show a 10-fold increase in volume during the dark period. In this period, silver grains were located on both “giant” and small-sized fibrillar centres. The fibrillar RNP component seen either at the periphery of fibrillar centres or in the form of a well-delimited network showed the strongest reaction. The same distribution of silver grains was observed in the sympathetic neurons of rats sacrificed during the light period. Here again, silver accumulation occurred exclusively in the fibrillar centres and the fibrillar RNP component. The same difference in reactivity was observed as for the dark period, the fibrillar RNP component being the main site of the reaction.

Evaluation of Nucleolar Organizer Regions in Human Bladder Cancers by Light- and Electron-Microscopic Morphometry

1998 ◽  
Vol 34 (5) ◽  
pp. 441-447 ◽  
Author(s):  
Toru Shimazui ◽  
Yasuo Uchiyama ◽  
Katsunori Uchida ◽  
Kazunori Hattori ◽  
Atsushi Takahashi ◽  
...  
Keyword(s):  
Nucleolar Organizer ◽  
Nucleolar Organizer Regions ◽  
Electron Microscopic ◽  
Human Bladder ◽  
Electron Microscopic Morphometry

scholarly journals ULTRASTRUCTURE OF THE NUCLEOLUS DURING THE CHINESE HAMSTER CELL CYCLE

1971 ◽  
Vol 49 (3) ◽  
pp. 830-847 ◽  
Author(s):  
J. S. Noel ◽  
W. C. Dewey ◽  
J. H. Abel ◽  
R. P. Thompson
Keyword(s):  
Cell Cycle ◽  
Fibrous Material ◽  
Chinese Hamster ◽  
Nucleolar Organizer ◽  
Chinese Hamster Cell ◽  
Nucleolar Organizer Regions ◽  
Electron Microscopic ◽  
Granular Component ◽  
Nucleolar Volume

Changes in the structure of the nucleolus during the cell cycle of the Chinese hamster cell in vitro were studied. Quantitative electron microscopic techniques were used to establish the size and volume changes in nucleolar structures. In mitosis, nucleolar remnants, "persistent nucleoli," consisting predominantly of ribosome-like granular material, and a granular coating on the chromosomes were observed. Persistent nucleoli were also observed in some daughter nuclei as they were leaving telophase and entering G1. During very early G1, a dense, fibrous material characteristic of interphase nucleoli was noted in the nucleoplasm of the cells. As the cells progressed through G1, a granular component appeared which was intimately associated with the fibrous material. By the middle of G1, complete, mature nucleoli were present. The nucleolar volume enlarged by a factor of two from the beginning of G1 to the middle of S primarily due to the accumulation of the granular component. During the G2 period, there was a dissolution or breakdown of the nucleolus prior to the entry of the cells into mitosis. Correlations between the quantitative aspects of this study and biochemical and cytochemical data available in the literature suggest the following: nucleolar reformation following division results from the activation of the nucleolar organizer regions which transcribe for RNA first appearing in association with protein as a fibrous component (45S RNA) and then later as a granular component (28S and 32S RNA).

The Growth of Herpesvirus mulatto in Human Fibroblast

1974 ◽  
Vol 32 ◽  
pp. 244-245
Author(s):  
Glennelle Washington ◽  
Philip P. McGrath ◽  
Peter R. Graze ◽  
Ivor Royston
Keyword(s):  
Rhesus Monkey ◽  
Microscopic Study ◽  
Electron Microscopic Study ◽  
Peripheral Blood ◽  
Human Fibroblast ◽  
Rhesus Monkeys ◽  
Human Fibroblasts ◽  
Electron Microscopic ◽  
Specific Antisera ◽  
Peripheral Blood Leucocytes

Herpes-like viruses were isolated from rhesus monkey peripheral blood leucocytes when co-cultivated with WI-38 cells. The virus was originally designated rhesus leucocyte-associated herpesvirus (LAHV) and subsequently called Herpesvirus mulatta (HVM). The original isolations were from juvenile rhesus monkeys shown to be free of antibody to rhesus cytomegalic virus. The virus could only be propagated in human or simian fibroblasts. Use of specific antisera developed from HVM showed no relationship between this virus and other herpesviruses. An electron microscopic study was undertaken to determine the morphology of Herpesvirus mulatta (HVM) in infected human fibroblasts.

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