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  • 1
    ISSN: 1432-0827
    Keywords: Electron probe microanalysis ; Secondary ion microanalysis ; Quail eggshell ; Biomineralization ; Elemental distribution, Sr, Mg, Ca
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Localization of mineral elements in the shell of quail eggs was studied by secondary ion mass spectrometry (SIMS) and electron probe microanalysis (EPMA). Normal eggs as well as eggs from hens intoxicated with strontium were studied. A simple preparative technique was employed that is advantageous for the study of mineralized tissues. Semithin (1 µm) sections of material embedded in Araldite were used. These preparations allow analysis by both SIMS and EPMA, and do not exhibit charge distortion in the resulting ion images. The greater sensitivity for detection of elements in low concentration and greater statistical reliability of images with SIMS allowed us to show the stepwise variations in concentration of Mg within normal and strontium-intoxicated quail eggshell. These steps were not detectable with EPMA. Strontium chloride added to the food was incorporated as Sr into the eggshell, which was abnormal in development. The incorporation of Sr does not correspond to the calcium distribution. The cone layer appears less rich in Sr, and it is also less rich in Mg in normal as well as in intoxicated eggs. From this distribution it is possible to construct a diagram of the abnormal eggshell which is difficult to distinguish by other methods. Electron diffraction of the quail eggshell intoxicated with Sr showed the carbonate to be in rhombohedric rather than orthorhombic form, even though the strontium concentration may be very high. These findings are a reflection of a complex process in dynamic equilibrium which is responsible for the biomineralization of the eggshell of quail.
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Calcified tissue international 25 (1978), S. 145-159 
    ISSN: 1432-0827
    Keywords: Bird egg shell ; Ultrastructure ; Calcification ; Electron diffraction ; Microanalysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary The egg-shell of Japanese quail was studied by several techniques. Semithin sections (1μm thick) of non-decalcified shell were observed by normal and polarized light microscopy. Thin sections of non-decalcified shell, examined by transmission electron microscopy, permitted us to observe the forms and dimensions of crystals of calcite within different layers of the shell: mammilary layer, layer of cones, palissade layer and surface crystal layer. There appears to be two distinct zones in the layer of cones as well as in the superficial crystal layer. Electron microdiffraction revealed the orientation of calcite crystals in the columns. Some crystal defects (twins?) were described and the possibility of their artefactual formation during ultramicrotomy is discussed. Localization of Ca, Mg, P and S were made by X-ray microanalysis of semithin sections. This technique shows that shell membranes, and chiefly the true cuticle, are also mineralized but, in these layers, minerals are not crystallized. Otherwise the distribution of Mg is not uniform throughout the shell thickness; it is less concentrated in the external zone of the layer of cones. These results together with observation of developing shells by scanning electron microscopy allowed us to propose a scheme for shell organization of the quail egg. This organization was related with decalcification which occurs during hatching.
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  • 3
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 8 (1987), S. 333-344 
    ISSN: 0886-1544
    Keywords: basal body migration ; cilia ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Immature oviduct implants from quails stimulated by estrogen to induce ciliogenesis were submitted to the in vitro action of benzodiazepines in organotypic culture. Diazepam and medazepam were added to the culture medium for 24 or 48 hours and tissues were examined by transmission and scanning electron microscopy for alterations in ciliary differentiation.Ciliogenesis was inhibited by both diazepam and medazepam, which affected mainly the migration of the basal bodies. Assembly of basal bodies was achieved normally in the cytoplasm, but their separation from generative complexes and migration toward the apical membrane were prevented. They remained in clusters around a deuteosome or eventually anchored to the close lateral plasma membrane.Furthermore, the drugs affected mature beating cilia, which then appeared lying tangentially to the cell surface. Relation between basal bodies and cortical cytoskeleton seemed to be altered by the drugs, which implies that the bearing of cilia and probably the ciliary beating movement were modified. Mocrovillus development was also altered by the action of these drugs.
    Additional Material: 21 Ill.
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  • 4
    ISSN: 0886-1544
    Keywords: cytoskeleton ; cell morphogenesis ; immunofluorescence ; antimyosin monoclonal antibody ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A monoclonal antibody, CC212, raised against ciliated cortices of quail oviduct cells and characterized as an antimyosin of smooth muscle and nonmuscle cells, was shown to specifically label a regular cortical network in Paramecium and to recognize two Triton X-100-insoluble polypeptides at 130 and 50 kDa. However, no evidence was obtained that these polypeptides are related to myosin.An immunofluorescence study and ultrastructural immunogold localization allowed us to identify the CC212-decorated material as a component of the outer lattice, a submembrane cytoskeletal network which runs along the top of the ridges visible by scanning electron microscopy and delineates the periphery of each cortical unit. The dynamics of the outer lattice during the cell cycle was studied by immunofluorescence and it was found that the outer lattice growth is achieved without disruption of the preexisting meshes by longitudinal elongation and additon of new transverse partitions. A striking disorganization of the outer lattice was observed in a thermosensitive mutant primarily altered in basal body duplication. These observations suggest possible functions of the outer lattice and demonstrate the interdependence of basal body duplication, surface growth, and outer lattice remodelling.
    Additional Material: 7 Ill.
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  • 5
    ISSN: 0886-1544
    Keywords: basal body ; centrosome ; ciliated epithelium ; ciliary rootlet ; cortex of metozoan ciliated cells ; monoclonal antibody ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Basal bodies from laying quail oviduct were semipurified and used as immunogen to produce monoclonal antibodies. On 38 clones obtained and among those staining the apical pole of the ciliated cell, CC-310 was chosen because it labeled the apical region with a punctated aspect, suggesting a staining of basal bodies or of basal body-associated structures; the basal pole was also labeled.The ultrastructural localization performed by the immunogold technique showed that the labeling was mainly associated with the striated rootlets. The basal feet, the side of the basal bodies, and the basal poles of the demembranated cells were also decorated. The identification of the antigen performed by immunoblots of deciliated cortices revealed two proteins of 175,000 and 40,000, whereas immunoblots of basal bodies showed only the 175,000-mw protein. The possibility of these two proteins sharing the same epitope, located at both poles of the cell, is discussed.Immunofluorescence ascertained that CC-310 decorated the striated rootlets in ciliated epithelia from other species: mussel, frog, and human tissue. Finally, when tested on cultured cell lines, CC-310 labeled the centrosome and its associated rootlets on PtK2 during interphase. During mitosis the poles of the mitotic spindle were stained without any apparent rootlet-like structure.
    Additional Material: 8 Ill.
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  • 6
    ISSN: 1432-0878
    Keywords: Ciliogenesis ; Actin ; Microfilaments ; Cytochalasin D ; Coturnix coturnix japonica (Aves)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The effects of cytochalasin D (CD) were studied by scanning (SEM) and transmission (TEM) electron-microscopic examination at different stages of ciliary differentiation in epithelial cells of quail oviduct. Immature quails were prestimulated by estradiol benzoate injections to induce ciliogenesis in the undifferentiated oviduct. After 24 h of CD culture, SEM study revealed inhibition of ciliogenesis and dilation of the apex of non-ciliated cells. TEM study showed that 2 h of CD treatment produced dilation of lateral intercellular spaces, after 6 h of treatment, this resulted in intracellular macrovacuolation. Vacuoles were surrounded by aggregates of dense felt-like material. CD also induced the disappearance of microvilli, and rounding of the apical surface of undifferentiated cells and those blocked in ciliogenesis. Centriologenesis was not inhibited by CD; basal bodies assembled in generative complexes in the supranuclear region after 24 h of treatment. However, the migration of mature basal bodies towards the apical surface was impaired. Instead, they anchored onto the membrane of intracellular vacuoles; growth of cilia was induced in the vacuole lumen. Cilium elongation was disturbed, giving abnormally short cilia with a dilated tip; microtubules failed to organize correctly.
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  • 7
    Publication Date: 1990-10-01
    Print ISSN: 0302-766X
    Electronic ISSN: 1432-0878
    Topics: Biology , Medicine
    Published by Springer
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  • 8
    Publication Date: 2013-06-21
    Description: Background: Pre-genomic and post-genomic studies demonstrate that chlamydiae actively recombine in vitro and in vivo, although the molecular and cellular biology of this process is not well understood. In this study, we determined the genome sequence of twelve Chlamydia trachomatis recombinants that were generated in vitro under antibiotic selection. These strains were used to explore the process of recombination in Chlamydia spp., including analysis of candidate recombination hotspots, and to correlate known C. trachomatis in vitro phenotypes with parental phenotypes and genotypes. Results: Each of the 190 examined recombination events was the product of homologous recombination, and no candidate targeting motifs were identified at recombination sites. There was a single deletion event in one recombinant progeny that resulted in the removal of 17.1 kilobases between two rRNA operons. There was no evidence for preference for any specific region of the chromosome for recombination, and analyses of a total of over 200 individual recombination events do not provide any support for recombination hotspots in vitro. Two measurable phenotypes were analyzed in these studies. First, the efficiency of attachment to host cells in the absence of centrifugation was examined, and this property segregated to regions of the chromosome that carry the polymorphic membrane protein (Pmp) genes. Second, the formation of secondary inclusions within cells varied among recombinant progeny, but this did not cleanly segregate to specific regions of the chromosome. Conclusions: These experiments examined the process of recombination in C. trachomatis and identified tools that can be used to associate phenotype with genotype in recombinant progeny. There were no data supporting the hypothesis that particular nucleotide selected sequences are preferentially used for recombination in vitro. Selected phenotypes can be segregated by analysis of recombination, and this technology may be useful in preliminary analysis of the relationship of genetic variation to phenotypic variation in the chlamydiae.
    Electronic ISSN: 1471-2180
    Topics: Biology
    Published by BioMed Central
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  • 9
    Publication Date: 1991-01-01
    Print ISSN: 0248-4900
    Electronic ISSN: 1768-322X
    Topics: Biology
    Published by Wiley
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  • 10
    Publication Date: 1988-01-01
    Print ISSN: 0248-4900
    Electronic ISSN: 1768-322X
    Topics: Biology
    Published by Wiley
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