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Localization of desmin and beta-tubulin during contracture in freshly isolated myocytes from the rat heart
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SCANDEM-90
not previously been reported in fiatworms. The vesicle and synapse types are similar to those observed in lower fiatworms.
The Cytoskeleton of Rat Spermatid and Spermatozoon. YvEs CLERMONT, RICHARD OKo and Louis HERMO, Department ofAnatomy, McGill University, Montreal, Canada The spermatozoon contains several cytoskeletal elements: in the tail there are, in addition to the axoneme, coarse outer dense fibres (ODF) and the fibrous sheath (FS). In the head, the nucleus is encapsulated by an additional cytoskeletal structure, the perinuclear theca, which has two parts, the perforatorium underlying the acrosomic system and the postacrosomal lamina. Using affinity purified antibodies prepared against proteins isolated from ODF, FS and perforatorium, the genesis of these structures was investigated in spermatids on sections of Epon- or Lowicryl-embedded tissues examined with the electron microscope. In the case of immunoreactive ODF, their growth extended from step 8 until step 19 of spermiogenesis and progressed in a proximal to distal direction. In addition to a diffuse immunoreactivity of the cytoplasmic matrix with the antibodies, there was a marked immunolabelling of ‘granulated bodies’ distributed throughout the cytoplasm of elongating spermatidsand which appeared to be transitory storage sites for proteins destined to form ODF. In the case of FS its growth took place from step 2 to step 17 of spermiogenesis in a distal to proximal direction. There was a selective immunoreactivity of the FS itself with FS antibodies but no reactivity over the plasma membrane-associated FS anlagen. In addition, there was a diffuse reactivity of the cytoplasmic matrix but storage cytoplasmic sites of the FS precursor proteins were not observed. In the case of the perforatorium, which is deposited over the nucleus during the last two steps of spermiogenesis, immuno-detected precursor proteins appeared in the nucleus and cytoplasm of spermatocytes and spermatids but were expelled from spermatid nuclei during steps 9 12 as the chromatin of these cells condensed. Thus the assembly of cytoskeletal elements was a lengthy multistep process that extended throughout spermiogenesis. (Supported by The Medical Research Council of Canada.)
Localization of Desmin and Beta-tubulin During Contracture in Freshly Isolated Myocytes from the Rat Heart. HELGE DALEN,* GOTTFRIED GREVEt and THORVALD SIETERSDAL,t *Laboratory of Clinical Electron Microscopy and tlnstitute of Anatomy, University of Bergen, Norway Freshly isolated adult myocytes from the adult rat heart were used for studying the localization of desmin and beta-tubulin during contracture of rod-shaped cells into ‘square cells’ and ‘round cells’. Samples were collected on Nucleopore filters and processed for SEM and TEM. Correlative immunocytochemical and immunohistochemical studies were performed on cells that were quick-frozen in Freon 22. The ultrastructural examination of the rod-shaped cells showed no visible structural injuries with the exception of torn nexuses. During contracture a number of spherical structures of variable sizes (i.e. ‘sub-sarcolemmal blebs’) developed on the cell surface. These blebs, surrounding a central core of irregularly oriented filaments, were entirely free of thick filaments and each usually contained several mitochondria and membrane vesicles. Thus, during contracture the myocytes were separated into two compartments, a central one consisting mainly of contractile filaments, and a peripheral one consisting mainly of mitochondria and components of the SR. Using monoclonal antibodies, we have shown by immunofluorescence and immunogold electron microscopy that desmin is confined to the outer parts of the central filamentous compartment, while beta-tubulin is specifically associated with the peripheral mitochondrial compartment.
SCANDEM-90
not previously been reported in fiatworms. The vesicle and synapse types are similar to those observed in lower fiatworms.
The Cytoskeleton of Rat Spermatid and Spermatozoon. YvEs CLERMONT, RICHARD OKo and Louis HERMO, Department ofAnatomy, McGill University, Montreal, Canada The spermatozoon contains several cytoskeletal elements: in the tail there are, in addition to the axoneme, coarse outer dense fibres (ODF) and the fibrous sheath (FS). In the head, the nucleus is encapsulated by an additional cytoskeletal structure, the perinuclear theca, which has two parts, the perforatorium underlying the acrosomic system and the postacrosomal lamina. Using affinity purified antibodies prepared against proteins isolated from ODF, FS and perforatorium, the genesis of these structures was investigated in spermatids on sections of Epon- or Lowicryl-embedded tissues examined with the electron microscope. In the case of immunoreactive ODF, their growth extended from step 8 until step 19 of spermiogenesis and progressed in a proximal to distal direction. In addition to a diffuse immunoreactivity of the cytoplasmic matrix with the antibodies, there was a marked immunolabelling of ‘granulated bodies’ distributed throughout the cytoplasm of elongating spermatidsand which appeared to be transitory storage sites for proteins destined to form ODF. In the case of FS its growth took place from step 2 to step 17 of spermiogenesis in a distal to proximal direction. There was a selective immunoreactivity of the FS itself with FS antibodies but no reactivity over the plasma membrane-associated FS anlagen. In addition, there was a diffuse reactivity of the cytoplasmic matrix but storage cytoplasmic sites of the FS precursor proteins were not observed. In the case of the perforatorium, which is deposited over the nucleus during the last two steps of spermiogenesis, immuno-detected precursor proteins appeared in the nucleus and cytoplasm of spermatocytes and spermatids but were expelled from spermatid nuclei during steps 9 12 as the chromatin of these cells condensed. Thus the assembly of cytoskeletal elements was a lengthy multistep process that extended throughout spermiogenesis. (Supported by The Medical Research Council of Canada.)
Localization of Desmin and Beta-tubulin During Contracture in Freshly Isolated Myocytes from the Rat Heart. HELGE DALEN,* GOTTFRIED GREVEt and THORVALD SIETERSDAL,t *Laboratory of Clinical Electron Microscopy and tlnstitute of Anatomy, University of Bergen, Norway Freshly isolated adult myocytes from the adult rat heart were used for studying the localization of desmin and beta-tubulin during contracture of rod-shaped cells into ‘square cells’ and ‘round cells’. Samples were collected on Nucleopore filters and processed for SEM and TEM. Correlative immunocytochemical and immunohistochemical studies were performed on cells that were quick-frozen in Freon 22. The ultrastructural examination of the rod-shaped cells showed no visible structural injuries with the exception of torn nexuses. During contracture a number of spherical structures of variable sizes (i.e. ‘sub-sarcolemmal blebs’) developed on the cell surface. These blebs, surrounding a central core of irregularly oriented filaments, were entirely free of thick filaments and each usually contained several mitochondria and membrane vesicles. Thus, during contracture the myocytes were separated into two compartments, a central one consisting mainly of contractile filaments, and a peripheral one consisting mainly of mitochondria and components of the SR. Using monoclonal antibodies, we have shown by immunofluorescence and immunogold electron microscopy that desmin is confined to the outer parts of the central filamentous compartment, while beta-tubulin is specifically associated with the peripheral mitochondrial compartment.