The Experts below are selected from a list of 129 Experts worldwide ranked by ideXlab platform
M O Soyer-gobillard - One of the best experts on this subject based on the ideXlab platform.
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Microtubule organization during the cell cycle of the primitive eukaryote dinoflagellate Crypthecodinium cohnii.
Journal of Cell Science, 1993Co-Authors: E Perret, J Davoust, M Albert, L Besseau, M O Soyer-gobillardAbstract:The complete microtubular system of the dinoflagellate Crypthecodinium cohnii Biecheler is described, as seen by confocal laser scanning fluorescence microscopy and labelling with anti-β-tubulin antibody. This technique allowed us to observe the organization of the subcorti cal and internal cytoskeletons and the mitotic micro tubular system, and their changes during the cell cycle. These observations are compared with those made in cryosections by light microscopy and in fast-freeze-fixed, cryosubstituted cells by electron microscopy. We show the organization of the cortical microtubules, and in particular of the thick microtubular bundles arranged as a three-pronged fork from which they seem to emanate. This fork emerges from a peculiar cytoplasmic zone at the pole of the cell and is in contact with the region of the Kinetosomes, at the cingulum. During the G 1 phase, only a single, radial microtubular bundle (a “desmose”) is observable in the inner part of the cyto plasm. One of its ends is near the flagellar bases and the other end is close to the nucleus in the centrosome region. During the S phase, the flagella drop off, the cell encysts and the Kinetosomes duplicate. In mitosis, the cortical microtubules and the intracytoplasmic microtubular bundles do not depolymerize. The microtubular fork, desmose and centrosome double and migrate, while the divided Kinetosomes stay in the same place. Later, the centrosomes organize the extranuclear spin dle, which is connected to the Kinetosome region by the microtubular desmose. The convergent end of the threepronged fork seems to be in contact with the centro some region. In early and mid-prophase, thick micro tubular bundles pass through the nucleus in cytoplasmic channels and converge towards the two poles. Asters were never seen at the spindle poles. The channels and microtubular bundles in the spindle double in number during late prophase and lengthen in early anaphase. The spindle bundles diverge in late anaphase, extend to very near the plasma membrane and depolymerize during telophase. The cleavage furrow in which tubulin and actin are characterized appears in anaphase, formed by invagination of plasma membrane in the Kinetosome region. The structure and rearrangements of the Crypthecodinium cohnii microtubular system are compared with those of other dinoflagellates and protists and of higher eukaryotes.
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Microtubule organization during the cell cycle of the primitive eukaryote dinoflagellate Crypthecodinium cohnii.
Journal of cell science, 1993Co-Authors: E Perret, J Davoust, M Albert, L Besseau, M O Soyer-gobillardAbstract:The complete microtubular system of the dinoflagellate Crypthecodinium cohnii Biecheler is described, as seen by confocal laser scanning fluorescence microscopy and labelling with anti-beta-tubulin antibody. This technique allowed us to observe the organization of the subcortical and internal cytoskeletons and the mitotic microtubular system, and their changes during the cell cycle. These observations are compared with those made in cryosections by light microscopy and in fast-freeze-fixed, cryosubstituted cells by electron microscopy. We show the organization of the cortical microtubules, and in particular of the thick microtubular bundles arranged as a three-pronged fork from which they seem to emanate. This fork emerges from a peculiar cytoplasmic zone at the pole of the cell and is in contact with the region of the Kinetosomes, at the cingulum. During the G1 phase, only a single, radial microtubular bundle (a "desmose") is observable in the inner part of the cytoplasm. One of its ends is near the flagellar bases and the other end is close to the nucleus in the centrosome region. During the S phase, the flagella drop off, the cell encysts and the Kinetosomes duplicate. In mitosis, the cortical microtubules and the intracytoplasmic microtubular bundles do not depolymerize. The microtubular fork, desmose and centrosome double and migrate, while the divided Kinetosomes stay in the same place. Later, the centrosomes organize the extranuclear spindle, which is connected to the Kinetosome region by the microtubular desmose. The convergent end of the three-pronged fork seems to be in contact with the centrosome region. In early and mid-prophase, thick microtubular bundles pass through the nucleus in cytoplasmic channels and converge towards the two poles. Asters were never seen at the spindle poles. The channels and microtubular bundles in the spindle double in number during late prophase and lengthen in early anaphase. The spindle bundles diverge in late anaphase, extend to very near the plasma membrane and depolymerize during telophase. The cleavage furrow in which tubulin and actin are characterized appears in anaphase, formed by invagination of plasma membrane in the Kinetosome region. The structure and rearrangements of the Crypthecodinium cohnii microtubular system are compared with those of other dinoflagellates and protists and of higher eukaryotes.
Purificacion Lopez-garcia - One of the best experts on this subject based on the ideXlab platform.
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The Ultrastructure of Sanchytrium tribonematis (Sanchytriaceae, Fungi incertae sedis) Confirms its Close Relationship to Amoeboradix
Journal of Eukaryotic Microbiology, 2019Co-Authors: Sergey Karpov, Andrey Vishnyakov, David Moreira, Purificacion Lopez-garciaAbstract:Fungi encompass, in addition to classically well-studied lineages, an everexpanding diversity of poorly known lineages that include, among others, zoosporic chytrid-like parasites. According to recent phylogenetic analysis based on 18S + 28S rRNA concatenated genes two unusual chytrid-like fungi Amoeboradix gromovi and Sanchytrium tribonematis form a monophyletic group, the family Sanchytriaceae, which represents a new divergent taxon that remains incertae sedis within Fungi. Zoospores of Amoeboradix gromovi contain one of the longest Kinetosomes known in eukaryotic cells, which are composed of microtubular singlets or doublets. However, the ultrastructure of S. tribonematis, the type species of the genus had not been yet studied. Here, we provide the results of TEM investigations of zoospores and sporangia from two strains of S. tribonematis. The two strains are endowed with unusual features. Like in A. gromovi, amoeboid zoospores of S. tribonematis contain a long Kinetosome composed of microtubular singlets, and the two orthogonal centrioles in their sporangia have nine microtubular singlets with an internal ring. The morphological and ultrastructural features of S. tribonematis are now included in the improved taxonomic diagnosis for this species.
E Perret - One of the best experts on this subject based on the ideXlab platform.
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Microtubule organization during the cell cycle of the primitive eukaryote dinoflagellate Crypthecodinium cohnii.
Journal of Cell Science, 1993Co-Authors: E Perret, J Davoust, M Albert, L Besseau, M O Soyer-gobillardAbstract:The complete microtubular system of the dinoflagellate Crypthecodinium cohnii Biecheler is described, as seen by confocal laser scanning fluorescence microscopy and labelling with anti-β-tubulin antibody. This technique allowed us to observe the organization of the subcorti cal and internal cytoskeletons and the mitotic micro tubular system, and their changes during the cell cycle. These observations are compared with those made in cryosections by light microscopy and in fast-freeze-fixed, cryosubstituted cells by electron microscopy. We show the organization of the cortical microtubules, and in particular of the thick microtubular bundles arranged as a three-pronged fork from which they seem to emanate. This fork emerges from a peculiar cytoplasmic zone at the pole of the cell and is in contact with the region of the Kinetosomes, at the cingulum. During the G 1 phase, only a single, radial microtubular bundle (a “desmose”) is observable in the inner part of the cyto plasm. One of its ends is near the flagellar bases and the other end is close to the nucleus in the centrosome region. During the S phase, the flagella drop off, the cell encysts and the Kinetosomes duplicate. In mitosis, the cortical microtubules and the intracytoplasmic microtubular bundles do not depolymerize. The microtubular fork, desmose and centrosome double and migrate, while the divided Kinetosomes stay in the same place. Later, the centrosomes organize the extranuclear spin dle, which is connected to the Kinetosome region by the microtubular desmose. The convergent end of the threepronged fork seems to be in contact with the centro some region. In early and mid-prophase, thick micro tubular bundles pass through the nucleus in cytoplasmic channels and converge towards the two poles. Asters were never seen at the spindle poles. The channels and microtubular bundles in the spindle double in number during late prophase and lengthen in early anaphase. The spindle bundles diverge in late anaphase, extend to very near the plasma membrane and depolymerize during telophase. The cleavage furrow in which tubulin and actin are characterized appears in anaphase, formed by invagination of plasma membrane in the Kinetosome region. The structure and rearrangements of the Crypthecodinium cohnii microtubular system are compared with those of other dinoflagellates and protists and of higher eukaryotes.
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Microtubule organization during the cell cycle of the primitive eukaryote dinoflagellate Crypthecodinium cohnii.
Journal of cell science, 1993Co-Authors: E Perret, J Davoust, M Albert, L Besseau, M O Soyer-gobillardAbstract:The complete microtubular system of the dinoflagellate Crypthecodinium cohnii Biecheler is described, as seen by confocal laser scanning fluorescence microscopy and labelling with anti-beta-tubulin antibody. This technique allowed us to observe the organization of the subcortical and internal cytoskeletons and the mitotic microtubular system, and their changes during the cell cycle. These observations are compared with those made in cryosections by light microscopy and in fast-freeze-fixed, cryosubstituted cells by electron microscopy. We show the organization of the cortical microtubules, and in particular of the thick microtubular bundles arranged as a three-pronged fork from which they seem to emanate. This fork emerges from a peculiar cytoplasmic zone at the pole of the cell and is in contact with the region of the Kinetosomes, at the cingulum. During the G1 phase, only a single, radial microtubular bundle (a "desmose") is observable in the inner part of the cytoplasm. One of its ends is near the flagellar bases and the other end is close to the nucleus in the centrosome region. During the S phase, the flagella drop off, the cell encysts and the Kinetosomes duplicate. In mitosis, the cortical microtubules and the intracytoplasmic microtubular bundles do not depolymerize. The microtubular fork, desmose and centrosome double and migrate, while the divided Kinetosomes stay in the same place. Later, the centrosomes organize the extranuclear spindle, which is connected to the Kinetosome region by the microtubular desmose. The convergent end of the three-pronged fork seems to be in contact with the centrosome region. In early and mid-prophase, thick microtubular bundles pass through the nucleus in cytoplasmic channels and converge towards the two poles. Asters were never seen at the spindle poles. The channels and microtubular bundles in the spindle double in number during late prophase and lengthen in early anaphase. The spindle bundles diverge in late anaphase, extend to very near the plasma membrane and depolymerize during telophase. The cleavage furrow in which tubulin and actin are characterized appears in anaphase, formed by invagination of plasma membrane in the Kinetosome region. The structure and rearrangements of the Crypthecodinium cohnii microtubular system are compared with those of other dinoflagellates and protists and of higher eukaryotes.
Sergey Karpov - One of the best experts on this subject based on the ideXlab platform.
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The Ultrastructure of Sanchytrium tribonematis (Sanchytriaceae, Fungi incertae sedis) Confirms its Close Relationship to Amoeboradix
Journal of Eukaryotic Microbiology, 2019Co-Authors: Sergey Karpov, Andrey Vishnyakov, David Moreira, Purificacion Lopez-garciaAbstract:Fungi encompass, in addition to classically well-studied lineages, an everexpanding diversity of poorly known lineages that include, among others, zoosporic chytrid-like parasites. According to recent phylogenetic analysis based on 18S + 28S rRNA concatenated genes two unusual chytrid-like fungi Amoeboradix gromovi and Sanchytrium tribonematis form a monophyletic group, the family Sanchytriaceae, which represents a new divergent taxon that remains incertae sedis within Fungi. Zoospores of Amoeboradix gromovi contain one of the longest Kinetosomes known in eukaryotic cells, which are composed of microtubular singlets or doublets. However, the ultrastructure of S. tribonematis, the type species of the genus had not been yet studied. Here, we provide the results of TEM investigations of zoospores and sporangia from two strains of S. tribonematis. The two strains are endowed with unusual features. Like in A. gromovi, amoeboid zoospores of S. tribonematis contain a long Kinetosome composed of microtubular singlets, and the two orthogonal centrioles in their sporangia have nine microtubular singlets with an internal ring. The morphological and ultrastructural features of S. tribonematis are now included in the improved taxonomic diagnosis for this species.
Stephan A. Hiller - One of the best experts on this subject based on the ideXlab platform.
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Ultrastructure of Prorodon (Ciliophora, Prostomatida) I. Somatic Cortex and Some Implications Concerning Kinetid Evolution In Prostomatid and Colpodid Ciliates
The Journal of Eukaryotic Microbiology, 1993Co-Authors: Stephan A. HillerAbstract:ABSTRACT. This study describes the ultrastructure of the somatic cortex of Prorodon aklitolophon and Prorodon teres. the meridionally arranged somatic kineties of both species can be separated into two parts: a short anterior part, which consists of a few somatic dikinetids (in which both Kinetosomes are ciliated), and a longer posterior consisting of monokinetids. the somatic monokinetids are associated with a convergent postciliary microtubular ribbon, a transverse microtubular ribbon flatly inserted in front of the Kinetosome, a short and steeply extending kinetodesmal fibre attached to kinetosomal triplet 5 and 7, and a desmose anterior to triplet 3. From this desmose, two to five prekinetosomal microtubules originate and extend anteriorly. the posterior Kinetosome of the somatic dikinetids is associated with the same microfibrillar and microtubular structures as the somatic monokinetid, except that no prekinetosomal microtubules originate from the desmose. the anterior Kinetosome has a single postciliary microtubule and a tangentially oriented transverse microtubular ribbon. the permanent collecting canals of the unique contractile vacuole system extend parallel and adjacent to the somatic kinetics of Prorodon. the collecting canals are supported by the prekinetosomal microtubules. A similarly organized contractile vacuole system is not yet known from any other ciliate group. One of the most surprising results of this investigation was finding a significant similarity between the somatic dikinetid pattern of Prorodon and the colpodid dikinetid pattern. A hypothesis is presented to illustrate the evolution of the somatic kinetid patterns in colpodid and prostomatid ciliates.
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Ultrastructure of Prorodon (Ciliophora, Prostomatida) Ii. Oral Cortex and Phylogenetic Conclusions
The Journal of Eukaryotic Microbiology, 1993Co-Authors: Stephan A. HillerAbstract:. The ultrastructure of the oral region and the ultrastructural architecture of the basket of Prorodon aklitolophon and Prorodon teres are described. the oral region of Prorodon consists of: 1) A circumoral kinety at the anterior pole of the cell surrounding the typically slit-shaped cytostomial funnel. This kinety is composed of inversely oriented dikinetids in which both Kinetosomes are ciliated and are associated with a very short postciliary microtubular ribbon and a few transverse microtubules; 2) Three brush rows aligned in parallel and extended meridionally in the anterior part of the cell. the individual brush rows consist of dikinetids, but in contrast to the dikinetids around the cytopharynx they are not inverted and only the anterior Kinetosomes bear specialized short brush cilia and are associated with a divergent-tangential transverse microtubular ribbon. the posterior Kinetosome is non-ciliated and bears a prominent convergent postciliary microtubular ribbon. Schematized dikinetid patterns of both oral regions of Prorodon are provided. In addition, a three-dimensional reconstruction of the basket of the genus Prorodon based on serial thin sections is presented. A phylogenetic tree, mainly based on stomatogenic data, is given to show the phylogenetic relationships of some prostomatid genera as well as the hypothesized sistergroup relationship of colpodid and prostomatid ciliates.
