Resistance to benzimidazole of Haemonchus contortus utkalensis in sheep on Martinique.
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Animals↗
Biomedical subjects
J Hubert
Publications and source records attributed to J Hubert.
The nuclear skeleton and the spatial arrangement of chromosomes in the interphase nucleus of vertebrate somatic cells.
The topologic distribution of interphase chromosomes established by using various cytologic methods and data concerning the DNA-nuclear skeleton interactions in isolated nuclear fractions were reviewed and discussed. Comparison of these different data clearly showed that the position of chromosomes observed in situ is in agreement with the results obtained from isolated nuclear fractions, indicating that all DNA molecules are bound to the peripheral nuclear skeleton. Moreover, the in situ position of the rDNA near the nuclear envelope can be correlated with the existence of a nucleolar skeleton connected to the peripheral nuclear skeleton. Taking into account the discrepant results regarding the actual existence of an internal nuclear skeleton, we attempted to analyze how the various nuclear skeletal structures described in the literature can be involved in both the distribution of chromosomes and in their chromatin organization. As many questions are still unanswered, we considered the modes of investigation that seem to be the most promising.
Animals↗
Analysis of sugar-binding sites in mammalian cell nuclei by quantitative flow microfluorometry.
Quantitative flow microfluorometry of neoglycoprotein (bovine serum albumin coupled to sugar and to fluorescein) binding demonstrated the existence of sugar-binding sites (i.e., lectin-like molecules) in isolated BHK cell nuclei. The very similar labeling intensities obtained with nuclei isolated by cell lysis and with permeabilized karyoplasts obtained by enucleation strengthened the idea that the binding sites are borne by actual nuclear structures and not by cytoplasmic or membrane-derived contaminants. With both nuclei-isolation procedures, neoglycoproteins (containing similar numbers of sugar residues) used as markers can be similarly classified. Fluorescence microscopy further indicated that in both nuclear preparations, the neoglycoprotein binding sites were associated with the nucleoli as well as with nucleoplasmic ribonucleoprotein elements. Nuclei from exponentially growing cells bound much greater amounts of neoglycoprotein than did nuclei from contact-inhibited cells.
Animals↗
Attachment of DNA to nucleolar and nuclear skeletal structures as visualized by Kleinschmidt molecular spreading.
Co-isolated residual nuclear shells and residual nucleoli from membrane-depleted rat liver nuclei were spread according to Kleinschmidt's method. Comparison of the spread residual structures isolated from nuclear shells and spread pore complex-lamina isolated from nuclear envelopes showed that these residual structures are morphologically identical. Furthermore, our nuclear shell isolation procedure allowed visualization of DNA strands bound to a granular component of the lamina. The fragmentation of nuclear shells allowed us to obtain well-spread nucleolar remnants, in which we observed DNA strands anchored on a residual nucleolar network attached to the lamina. The different molecular features revealed by the spreading of residual nucleolar structures suggest that both non-transcribing nucleolar DNA and active ribosomal genes are linked to the nucleolar network. Although the exact nature of this network remains to be defined, the results of the present study strongly suggest that the DNA molecules of the chromosomes bearing ribosomal genes have many sites of attachment to a non-chromatin nucleolar network which can be referred to as a nucleolar skeletal complex.
Animals↗
Benzimidazole resistance in field strains of nematodes from goats in France.
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Animals↗
New data on the in-situ position of the inactive X chromosome in the interphase nucleus of human fibroblasts.
The in situ spatial distribution of nucleolus-organizing-region (NOR) bearing chromosomes in relation to the inactive X chromosome was studied during interphase in human fibroblasts. The respective positions of these chromosomes were examined in 30 growing and 32 resting fibroblasts from reconstructed nuclei, using nucleoli and the Barr body as ultrastructural markers. Experimental values for the distance between the nucleoli and the Barr body were estimated by their coefficient of closeness and compared to the uniform distribution. The following results were obtained: the distribution patterns for the two populations of nuclei were similar, the distribution of the NOR-bearing chromosomes in relation to the inactive X chromosome varied and differed significantly from a uniform distribution, and in many cases the Barr body was observed to be in a juxta-nucleolar position. The internal distribution revealed by this study is compared with the data in the literature, especially with the conflicting data obtained by other methods used to determine the interphase arrangement of chromosomes. The relationship between interphase and metaphase arrangements such as can be deduced with these methods, is discussed in relation to the mechanisms of the formation of metaphase plates or chromatid translocations.
Cell Nucleolus↗
Detection of sugar-binding proteins in membrane-depleted nuclei.
Nuclear sugar-binding proteins were detected in membrane-depleted nuclei isolated from hamster BHK cells and mouse L 1210 leukemia cells by means of fluorescein-labelled neoglycoproteins. In fluorescence microscopy, the fluorescence was seen throughout the nucleus but was generally brighter over the nucleoli than over the rest of the nucleus. Flow cytofluorometry analysis demonstrated the presence of nuclear sugar-binding proteins for synthetic glycoproteins associated with different sugar residues. Among the nine neoglycoproteins used, four neoglycoproteins (namely alpha-rhamnosylated, alpha-glucosylated, N-acetyl-beta-glucosaminylated and alpha-mannosylated-6P-serum albumin) strongly labelled nuclei. Various controls strongly argue for the specificity of the nuclear labelling. The possibility that some of the sugar-binding proteins might correspond to endogenous nuclear lectins is considered.
Animals↗
Characterization of lamina-bound chromatin in the nuclear shell isolated from HeLa cells.
The structure and the polypeptide composition of the nuclear shell isolated from interphase HeLa cells have been investigated and compared to those of the intranuclear material. The isolated nuclear shell contains chromatin superstructures (28-32 nm thick fibres) made of tightly packed nucleosomes that resist low ionic strength conditions and that are associated with the three nuclear lamins. Chromatin in the nuclear shell exhibits very simple chemical composition. Especially, non-histone proteins are lacking. The results presented here rule out the possibility that the nuclear shell results from contamination of lamina by intranuclear elements. They suggest that the lamins are directly involved in the specific properties and in the organization of chromatin in the nuclear shell.
Cell Fractionation↗
In situ ultrastructural localization of sugar-binding sites in lizard granulosa cell nuclei.
Mannose-binding sites were detected at the ultrastructural level in nuclei of lizard granulosa cells in situ by means of mannosylated ferritin. When ultrathin sections of material embedded in glycol methacrylate were incubated with mannosylated ferritin, a strong labelling was observed over nucleoli, chromatin and the external leaflet of the nuclear envelope, but no labelling was detected in the perinuclear space except for nuclear pores. This labelling was clearly inhibited when sections were incubated in a solution containing both mannosylated ferritin and a sugar-related neoglycoprotein (mannosylated serum albumin). These ultrastructural data supporting the existence of nuclear lectin-like components in reptilian cells are in agreement with our previous findings about such components in nuclei isolated from mammalian cells. Owing to the unique organization of the granular component of the nucleoli in specialized granulosa cells, we are able to show that some of the mannose-binding sites are associated with ribosomal precursors.
Animals↗
Nuclear RNA-associated proteins and their relationship to the nuclear matrix and related structures in HeLa cells.
The ultrastructure and the polypeptide composition of residual nuclear substructures including nuclear matrices, nuclear ghosts, and residual envelopes were investigated by means of electron microscopy and two-dimensional gel electrophoresis. Nuclear matrices were prepared by digesting isolated nuclei with DNase I alone, followed by high-salt extraction in 2 M NaCl. Nuclear ghosts were obtained by high-salt extraction of nuclei previously digested with DNase and RNase in MgCl2-containing buffers. To prepare residual envelopes, nuclei were first digested with RNase in the presence of EDTA, then digested with Mg2+ -activated DNase I, and extracted in 2 M NaCl. The results of this comparative study support the conclusion that the intranuclear matrix is made of two distinct RNA-containing elements. One of these elements appears on ultrathin sections as a thin fibrillar network. It disappears from RNase-digested nuclei, together with numerous basic proteins, whatever the conditions of digestion. Although this element is present in extranucleolar territories, it is a major component of residual nucleoli. The second element appears as coarse-beaded fibers absent from the nucleolar areas. Its preservation in residual nuclear substructures depends on the presence of Mg2+ ions during RNase digestion of nuclei. It is enriched in two minor basic proteins of relative mass 49 000 and 70 000. The involvement of this fibrogranular element in heterogeneous nuclear RNA attachment to the nuclear matrix is discussed.
Cell Fractionation↗
Structural aspects of intranuclear matrix disintegration upon RNase digestion of HeLa cell nuclei.
The organization of the intranuclear elements observed in histone-depleted (2 M NaCl-extracted) HeLa cell nuclei was investigated by means of electron microscopy and two-dimensional gel electrophoresis. This work was mainly aimed at verifying whether or not an intranuclear skeleton or matrix existed, which could explain the stable attachment of RNA to the residual nuclear structure after high-salt extraction, and its three-dimensional organization. We compared the ultrastructure and the polypeptide composition of RNA-containing and RNA-depleted (RNase-treated) nuclear residues, and we visualized intermediate stages of RNase action on the intranuclear material. We showed that this material was made of two types (fibrillar and granular) of salt-resistant RNP components equally sensitive to RNase when the enzyme was used prior to high-salt extraction. At least in our material and under our experimental conditions, no intranuclear matrix could be distinguished from the residual RNP material. Our results further suggest that formation of such a matrix is a path-dependent phenomenon.
Cell Nucleus↗
[Proposal of a finer classification of diving goiters. Apropos of a series of 112 cases].
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Goiter, Substernal↗
Study of gastro-intestinal strongylosis in a sheep flock on permanent pasture 2. Sheep parasitism in 1978-1979.
The epidemiological study carried out in 1977 in the Limousin region of France was continued for the next two years. Eighty-five lambs were slaughtered at the rate of five animals every weeks: sixty were slaughtered from May 1978 to March 1979 and twenty-five from May to September 1979. Total parasite counts and coprological examinations were carried out. In spring the infestation of the lambs was early and heavy, and revealed that certain free-living stages can survive in low temperatures. The pattern of development of the parasites differed according to the year. It was concluded that control programmes based on theoretical patterns of evolution of the parasite will need profound study of climatic variations. Three species were found most frequently: Ostertagia circumcincta, Nematodirus spp. and Trichostrongylus colubriformis. Haemonchus contortus, exceptionally numerous in 1977, did not return to its normal level until 1979. A significant correlation was demonstrated between the number of eggs per gram of faeces and the number of female adult parasites. Thus the usefulness of coprological examinations in the diagnosis of ovine digestive strongylosis was proven. In spite of relatively high parasitism, no significant difference was found over the two years between the weight gains of regularly treated and untreated lambs.
Animals↗
[Trial approach to certain psychosomatic aspects of the asthmatic syndrome].
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Asthma↗
Three-dimensional approaches to the residual structure of histone-depleted HeLa cell nuclei.
Histone-depleted nuclei were prepared by high-salt extraction of interphase HeLa cell nuclei. A large amount of the nuclear DNA remained associated with a rapidly sedimenting residual nuclear structure including cytoplasmic (intermediate filament) and nuclear (matrix and lamina) proteins. Electron microscopy allowed detection in the insoluble structure of a residual nuclear envelope, nucleolar residues, and an intranuclear network whose correspondence with components of in situ fixed nuclei is discussed. Using three-dimensional electron microscopy, it is further demonstrated that the salt-insoluble structure remaining after histone depletion in 2 M NaCl is highly ordered. This is of the utmost importance when considering the roles reportedly ascribed to this structure in nuclear functions.
Cell Nucleolus↗
[Compression of the brachial plexus by a pseudarthrosis of the 1st rib].
The authors have described the case of a thoracic outlet syndrome with costoclavicular compression of the brachial plexus, secondary to non-union of a first rib fracture. Treatment consisted in transaxillary removal of the first rib, as described by Roos. Intrafascicular neurolysis of the posterior and medial trunks was performed at the same time, and was followed by quick clinical and electromyographical recovery.
Adult↗
Anchorage of the nucleolus in the pore complex-lamina by a DNA-bearing structure masked in situ in rat liver nuclei.
We have developed a method by which nuclear shells containing nucleoli can be isolated from membrane-depleted rat liver nuclei. This method involves the removal of the internal chromatin. This chromatin is expelled from the nuclear shell using combinations of low and high ionic strength buffers. The expelled internal part is subsequently digested with DNase I or micrococcal nuclease. Examination by electron microscopy of the nuclear and the nucleolar structures at various steps of the isolation procedure shows that the nucleoli are anchored in the peripheral lamina by a pedicle that is continuous with an intranucleolar network. This network is masked in situ by nucleolar granules. The pedicle and the network which support the nucleolar DNA are composed mainly of non-histone proteins insoluble in 2M NaCl.
Animals↗
In situ distribution in different cell types of nuclear glycoconjugates detected by two lectins.
Nuclear glycoconjugates were detected in situ by two lectins--Concanavalin A and Wheat germ agglutinin--on tissue sections embedded in the hydrophilic resin glycol methacrylate. These lectins were conjugated with fluorescein isothiocyanate for fluorescence microscopy, and labelled with ferritin for electron microscopy. The ovarian follicle of the lizard Lacerta vivipara was chosen for this study, because it enables four types of nuclei, with different ultrastructures and physiology to be observed on the same section. In this material, all the nucleoli were found to contain a high concentration of receptors for both lectins. The distribution of the receptors located in the chromatin and nucleoli was observed to vary within the same type of nucleus, depending on the lectin used. Some of our results suggest that increased labelling by Wheat germ agglutinin might depend on increased production of ribosomal precursors.
Animals↗