Association between the nucleolus and the coiled body

By means of light and electron microscopic immunocytochemistry, we have localized p80-coilin, a specific protein marker for coiled bodies, in mammalian cell lines as well as in primary rat neuron cultures. p80-coilin-stained nuclear bodies, which also contained fibrillarin, could be subsequently silver stained by a method specific for the visualization of nucleolar organizer regions. In cycling cells, most coiled bodies were not associated with nucleoli, whereas in rat neurons such as association was frequent. The treatment of cycling cells with actinomycin D or 5,6-dichloro-1-beta-D-ribo furanosyl-benzimidazole led to nucleolar segregation and/or disintegration, and to an association of p80-coilin staining structures with nucleoli. p80-coilin-positive structures contained fibrillarin in both untreated and treated cells. These results support the opinion that there might be a special association between coiled bodies and nucleoli, particularly in neuronal cells.

Immunocytochemistry of the cell nucleus

This electron microscopic review addresses in situ immunocytochemistry of the mammalian cell nucleus with special reference to the use of autoantibodies, which are the major source of antinuclear antibodies. The localization of many key nuclear antigens is documented and immunocytochemical data are related to the major functional processes of transcription and processing of RNA and to replication of DNA.

Ultrastructural immunolocalization of cyclin/PCNA in synchronized 3T3 cells

The immunolocalization of cyclin/PCNA in synchronized 3T3 cells was performed with human autoantibodies using an immunogold technique performed on thin cryosections. Previous immunofluorescent studies demonstrated that the DNA replication sites correspond to the localization of bound cyclin. We have found that in the early periods of S phase, the DNA replication sites (or sites potentially ready for the replication during the hydroxyurea DNA synthesis block) are situated in the perichromatin region and correspond to clustered gold particles present frequently over a morphologically distinct small nuclear area. Heavily labeled chromocenters, including perinucleolar condensed chromatin, exhibiting several such distinct areas were found in later periods of S phase.

[Functional ultrastructure of the thyroid gland in rats]

Thyroid gland from normal and hormonally influenced rats (by application of exogenous Triiodothyronine and Thyroid stimulating Hormone), were investigated by means of classical electron microscopy. Dense granules, micropinocytotic and macropinocytotic structures were observed similarly as was already published. Triiodothyronine and Thyroglobulin were localized by affinity cytochemistry on ultrathin cryosections from normal rat thyroid gland. These method showed, that particular endocytotic and exocytotic structures can't be distinguish only by simple morphology and that functional status of these structures can be evaluated only by detection of contained molecules. Triioodthyronine was observed by affinity cytochemistry in multivesicular bodies and in lateral intercellular spaces. That findings indicate, that Triiodothyronine is internalized (transcytosed) by Receptor-mediated endocytosis. Affinity cytochemistry is useful for study of triiodothyronine and thyroglobulin movement in the thyroid gland.

Immunolocalization of 7-2-ribonucleoprotein in the granular component of the nucleolus

Certain autoimmune sera contain antibodies against a nucleolar ribonucleoprotein particle associated with 7-2-RNA (R. Reddy et al. (1983) J. Biol. Chem. 258, 1383; C. Hashimoto and J. A. Steitz (1983) J. Biol. Chem. 258, 1379). In this study, we showed by immunofluorescence microscopy that antibodies reactive with 7-2-ribonucleoprotein immunolocalized in the granular regions of actinomycin D and 5,6-dichloro-1-beta-D-ribofurano-sylbenzimidazole (DRB)--segregated nucleoli from Vero cells. By electron microscopic immunocytochemistry, antigen-antibody complexes were located in the granular component of transcriptionally active nucleoli from rat liver hepatocytes and HeLa cells. Anti-7-2-RNP antibodies from two autoimmune sera immunoprecipitated a major protein of Mr 40,000 from [35S] methionine--labeled HeLa cell extract. The immunolocalization data suggest that 7-2-ribonucleoprotein may be involved in stages of ribosome biogenesis which take place in the granular component of the nucleolus, i.e., assembly, maturation, and/or transport of preribosomes.

Internalization of triiodothyronine-bovine serum albumin-colloidal gold complexes in human peripheral leukocytes

Complexes of triiodothyronine-bovine serum albumin-colloidal gold were specifically internalized in human peripheral leukocytes after 5 min of incubation. The specificity was partially lost after a longer incubation.

Binding of (125I) triiodothyronine to human peripheral leukocytes and its internalization

Ultrastructural autoradiography showed high specific binding of (125I) triiodothyronine, as confirmed by a competition test, to plasma membranes, nuclei and mitochondria of human peripheral leukocytes. A high level of binding was also noted on the granulocytes' granules, especially in eosinophils.

Autoantibodies in hypertrophic cardiomyopathy and their clinical significance

Data concerning autoantibodies in hypertrophic cardiomyopathy are rare and controversial and only the results of indirect immunofluorescence methods are available in the literature. The aim of this study was to determine the frequency and clinical significance of autoantibodies in hypertrophic cardiomyopathy by means of the Western blot which is a highly sensitive immunological technique. Sera from twelve (48.0%) of the whole group of 25 patients with hypertrophic cardiomyopathy reacted with actin from the HeLa extract. The incidence of anti-actin antibodies in sera from 23 ischaemic heart disease patients was 13.0% (P less than 0.025) and in 37 apparently healthy subjects was 8.1% (P less than 0.001). When samples were assayed on the actomyosin prepared from Xenopus laevis muscle, sera of 14 (56.0%) of the patients exhibited actin positivity while the positivity in ischaemic heart disease and in healthy subjects was found to be 13.0 and 13.5%, respectively (P less than 0.001). Presence of anti-actin antibodies was related to the functional and clinical status and the progression of the disease. Anti-actin antibodies were found more frequently in medically treated patients. These data suggest that anti-actin antibodies are probably not directly involved in the pathogenesis of hypertrophic cardiomyopathy, but their detection might be useful as an additional marker of disease severity.

High sensitivity immunolocalization of double and single-stranded DNA by a monoclonal antibody

A monoclonal antibody (AK 30-10) is described which specifically reacts with DNA both in double and single-stranded forms but not with other molecules and structures, including deoxyribonucleotides and RNAs. When used in immunocytochemical experiments on tissue sections and permeabilized cultured cells, this antibody detects DNA-containing structures, even when the DNA is present in very small amounts. Examples of high resolution detection include the DNA present in amplified extrachromosomal nucleoli, chromomeres of lampbrush chromosomes, mitochondria, chloroplasts and mycoplasmal particles. In immunoelectron microscopy using the immunogold technique, the DNA was localized in distinct substructures such as the "fibrillar centers" of nucleoli and certain stromal centers in chloroplasts. The antibody also reacts with DNA of chromatin of living cells, as shown by microinjection into cultured mitotic cells and into nuclei of amphibian oocytes. The potential value and the limitations of immunocytochemical DNA detection are discussed.

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.

[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.

[Preparation of colloidal gold and its macromolecular complexes]

A critical presentation of basic methods for the preparation of colloid gold and of gold particle complexes with macromolecules to be used on the ultrastructural level.

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.

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.

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.

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.

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.

Structure of plain and complex flagellar hooks of Pseudomonas rhodos

The proximal hooks of plain and complex flagella produced by a strain of Pseudomonas rhodos have been analyzed by electron microscopy and optical diffraction and filtering. Plain flagellar hooks are cone-shaped, 70 nm long, and 13 to 21.5 nm wide, and consist of helically arranged subunits. Complex flagellar hooks are cylinders, 180 to 190 nm long, and 15 to 16 nm wide, and are composed of globular subunits. The structure comprises four small-scale helical rows of subunits intersecting bewteen 10 and 11 large-scale helices of pitch angle 80 degrees. The axial and lateral dimensions of the unit cell, which define the surface lattice, are 4.9 and 4.7 nm, respectively. In addition, a core structure, approximately 5 nm wide, has been demonstrated inside the hook cylinder. Complex flagellar hooks were isolated and purified by gradient centrifugation after acid degradation of the attached filaments. Isolated hook particles have an average sedimentation constant of 130S and consist of a protein of molecular weight 43,000. A model of the complex flagellar hook is presented, and its possible role in flagellar assembly and rotation is discussed.