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Biomedical subjects

I Raska

Publications and source records attributed to I Raska.

At least 73 records · Page 4Linked to original sources
PubMed1985

Ultrastructural localization of rRNA in HeLa cells, rat liver cells and Xenopus laevis oocytes by means of the monoclonal antibody--protein a--gold technique.

The postembedding localization of rRNA was investigated in ultrathin sections of HeLa cells, rat liver and Xenopus laevis oocytes by means of the monoclonal antibody to rRNA and protein A-gold technique. The incidence of gold particles was highest in nucleoli and cytoplasmic areas containing ribosomes. The chromosomes were labelled less than the surrounding cytoplasm in mitotic HeLa cells. In nucleoli of HeLa cells and rat hepatocytes, the labelling of areas containing ribonucleoprotein components was greater than the labelling of fibrillar centres. In segregated nucleoli of X. laevis oocytes, the labelling of the granular region substantially exceeded that of the fibrillar regions. The incidence of nucleoplasmic gold particles in interphasic HeLa cells was found to be slightly increased in the vicinity of nucleoli. The labelling of clusters of interchromatin granules in rat hepatocytes was not significantly different from that of the rest of the nucleophasmic interchromatin spaces.

Animals↗
PubMed1985

[Use of colloidal gold in ultrastructural cytochemistry].

Colloid gold stabilized by macromolecules with various binding characteristics proved to be usable in transmission electron microscopy: Nucleic acids localization was studied in tissue cultures after embedding by techniques autoimmune serum-protein A--gold and RNase--gold. Technique with serum autoantibodies against double-stranded DNA resulted in marking condensed chromatin. Further experiments with ultrastructural localization of other autoimmune components seemed to be perspective and of diagnostic importance. Technique with RNase--gold complex marked especially ribosomes, nucleolus and interchromatin nuclear spaces. Herpes virus, rotavirus and enterovirus were identified in negative contrast by the technique antivirus serum--protein A--gold. A higher warrant of evidence achieved by the method may be used in virologic diagnosis. A small amount of tubulin was found in isolated permeabilized nuclei of Xenopus laevis by a direct immunocytochemical method with complex monoclonal IgG against tubulin-gold. Binding of complex of triiodothyronine-bovine serum albumin--gold on the cytoplasmic membrane of LEP cells in a short term tissue culture showed a possibility of tracing non-peptidic hormones binding on specific receptors.

Animals↗
PubMed1983

Analysis of ring-shaped nucleoli in serially sectioned human lymphocytes.

Serial section analysis has demonstrated that ring-shaped nucleoli of mature human lymphocytes are spherical structures consisting of a peripheral ribonucleoprotein shell that surrounds one large fibrillar center. The shell exhibits usually one or, less frequently, two openings. The fibrillar center is in contact with the nucleoplasm and perinucleolar condensed chromatin, which frequently appears as a pedicle-like structure. Several chromocenters are associated with the ring-shaped nucleolus.

Cell Nucleolus↗
PubMed1983

Ultrastructural localization of DNA in tissue culture cell nuclei by means of enzyme-gold and autoimmune sera-protein A-gold techniques.

The post-embedding localization of DNA was investigated in cell nuclei by means of DNase I-gold and autoimmune sera-protein A-gold techniques. Using the former technique, gold particles were found mainly over euchromatin, nucleoli exhibit occasionally high labeling. In the latter technique, the use of the serum binding dsDNA confined the label mainly to condensed chromatin.

Actins↗
PubMed1983

Immunocytochemical localization of cytoskeletal proteins and histone 2B in isolated membrane-depleted nuclei, metaphase chromatin, and whole Chinese hamster ovary cells.

Immunocytochemical techniques employing protein A-gold labeling were used to locate actin, tubulin, and histone 2B in thin sections of embedded, isolated membrane-depleted nuclei, metaphase chromosomes, and whole Chinese hamster ovary (CHO) cells. Actin and tubulin were detected in significant amounts in the cytoplasm and the nucleus of whole cells. The isolated membrane-depleted nuclei and metaphase chromosomes showed levels of actin and tubulin labeling either comparable to or sometimes lower than the levels of labeling in whole interphase cells. The results suggest that actin and tubulin are normal components of nuclei throughout the cell cycle. A mouse monoclonal antibody to histone 2B gave relatively weak labeling of nuclei and chromosomes in whole cells but intense labeling of isolated nucleoids and chromosomes. An increased concentration of antibody at the periphery of interphase nucleoids was noted.

Actins↗
PubMed1983

Fibrillar centres and condensed nucleolar chromatin in resting and stimulated human lymphocytes.

To provide more information on the ultrastructural morphology of fibrillar centres and condensed nucleolar chromatin, both these nucleolar components were studied in ultrathin sections of resting and phytohemagglutinin stimulated human lymphocytes. In comparison with resting cells, in stimulated lymphocytes fibrillar centres increased in number but their total size was smaller. In stimulated cells the size of individual fibrillar centers remained about the same. The size of the intranucleolar condensed chromatin was larger in stimulated than in resting cells. The proportion of the intranucleolar areas with condensed chromatin to the whole nucleolar area was relatively constant since no difference was noted between resting and stimulated cells. On the other hand, the proportion of the condensed intranucleolar chromatin to the condensed perinucleolar chromatin increased in stimulated lymphocytes in comparison with resting cells. The close morphological relationship between fibrillar centres and condensed intranucleolar chromatin was noted in ring shaped nucleoli of resting lymphocytes, this relationship was frequently remaining in nucleoli with less or more distinct nucleolonemata of stimulated cells.

Cell Nucleolus↗
PubMed1982

Optical diffraction analysis of crystalline inclusions in the rough endoplasmic reticulum of islet parenchymal cells of the hagfish, Myxine glutinosa.

Optical diffraction analysis was carried out on crystalline inclusions in the rough endoplasmic reticulum of the insulin and somatostatin cells in the islet organ of the hagfish. A striking difference in crystalline arrangement was observed between the inclusions of the insulin and somatostatin cells. The crystallographic arrangement of the inclusions observed in situ in the insulin cells differed from that previously found by means of X-ray diffraction analyses of hagfish insulin crystals formed in vitro.

Animals↗
PubMed1981

Further ultrastructural studies on lymphocytic micronuclei.

The ultrastructural changes of ring-shaped nucleoli in human blood lymphocytes produced with actinomycin D were compared with naturally occurring modification of ring-shaped nucleoli and micronucleoli in mouse thymic lymphocytic. Similarly to those in other nucleoli, these changes were characterized by the segregation of nucleolar components, appearance of very dense granular and fibrillar components, formation of dense plaques as well as dense nucleolar caps and nucleolar fragmentation. In addition, some of the observed changes were specific for the ring-shaped nucleoli i. e. formation of horse shoe-like and beaded nucleoli with the segregation of RNP components in the nucleolar peripheral ring. Some of the nucleolar changes produced with actinomycin D were also similar to the naturally occurring ultrastructural characteristics of micronucleoli in small mouse thymic lymphocytes.

Animals↗
PubMed1980

Further studies on ring shaped nucleoli and micronucleoli of human peripheral lymphocytes.

Peripheral human lymphocytes were studied in short term tissue cultures to provide more information on the relationship between ring shaped nucleoli and micronucleoli in these cells. The cultivation of peripheral lymphocytes with actinomycin D produced a transformation of ring shaped nucleoli to micronucleoli. Therefore, nucleolar types and particularly micronucleoli cannot indicate the lymphocytic origin. THe horse-shoe like nucleoli or beaded ring shaped nucleoli possibly represent intermediate nucleolar stages between ring shaped nucleoli and micronucleoli. Ring shaped nucleoli apparently reflect low nucleolar RNA synthesis and micronucleoli a complete inhibition of this process.

Cell Nucleolus↗
PubMed1978

Fine structure of crystalline inclusions in B-cells of the islets of Langerhans in the alligator.

The ultrastructure of crystalline beta granules of the islets of Langerhans in the alligator has been investigated. From optical diffraction analysis and serial sectioning, the existence of four distinct types of crystalline inclusions was established in ultrathin sections. The first type is the most frequent and is interpreted as a rhombohedron with a base, the ortho-hexagonal unit-cell edges being a equal to 18.9 nm, c equal to 23.0 nm. The second type of crystal (not observed in serial sections) is found compatible with a rhomb-dodecahedron which indexes on a cubic cell with a equal to 9.6 nm. The third type of crystal was assigned to dipyramids. Dipyramids are extremely rare, and only two diffraction patterns were obtained; their crystal system could not be determined. Prisms, which are second in abundance, represent the fourth type of crystal. Spacings as well as the symmetry differ from those of the above three crystal types and indicate a tetragonal cell with a equal to 4.2 nm, c equal to 14.2 nm. The data for the prismatic crystals are strikingly similar to those of proinsulin and may represent the first case of agreement between crystals (i) formed in vitro and studied by X-ray diffraction and (ii) those investigated in situ by electron microscopy.

Alligators and Crocodiles↗
PubMed1978

A further contribution on nucleoli of human lymphocytes.

Cultured human lymphocytes were investigated by means of light as well as electron microscopic procedures to provide more information on the structural organization of their nucleoli. The transformation of ring shaped nucleoli to nucleoli with less or more distinct nucleolonemata in PHA stimulated cells was characterized by a marked increase of granular RNP components in number indicating the activation of their production. This phenomenon seems to be related not only to the activation of the ribosomal RNA synthesis but also to its processing. The appearance of fibrillar RNP components in the central area of the ring shaped nucleoli apparently represents the first sign of the nucleolar RNA synthesis in these cells. The proportion of fibrillar and granular nucleolar RNP comonents in PHA inresponsive lymphocytes was similar to that in lymphocytes from patients with the usual type of lymphocytic leukemia. The intranucleolar chromatin areas appeared to be larger in PHA stimulated lymphocytes but the proportion of these areas to the nucleolar body did not show substantial difference as compared to the resting cells.

Cell Nucleolus↗