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  • 1985-1989  (1,418)
  • 1975-1979
  • 1890-1899
  • 1987  (1,418)
  • Cell & Developmental Biology  (1,362)
  • Electron microscopy
Material
Years
  • 1985-1989  (1,418)
  • 1975-1979
  • 1890-1899
Year
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Virchows Archiv 411 (1987), S. 311-314 
    ISSN: 1432-2307
    Keywords: Human pituitary adenomas ; Granules ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Light bodies are large cytoplasmic granules originally described in the gonadotrophic cells of the rat pituitary gland. In order to determine whether similar bodies occur in the human anterior pituitary gland, 89 pituitary adenomas and periadenomatous tissue from 20 cases were examined by transmission electron microscopy. Double membrane bound bodies with filamentous internal structure identical to rodent light bodies were identified in 10 hormone-producing adenomas: 5 PRL, 1 PRL-GH, 2 GH, and 2 ACTH-producing tumours. No light bodies were found in the remaining 79 tumours nor in the pituitary cells in periadenomatous tissue from 20 cases. These results show that some human pituitary adenomas may contain light bodies identical to those seen in gonadotrophs of rat pituitary.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Virchows Archiv 410 (1987), S. 83-92 
    ISSN: 1432-2307
    Keywords: Buschke-Loewenstein tumour ; Giant condyloma ; Anogenital region ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Results on the light- and electron microscopic studies of six cases of Buschke-Loewenstein tumour are presented. The role of chronic irritation is emphasized in the aetiology of the tumour. Fistulas and abscesses arising in the tumour are dangerous as they give rise to chronic sepsis. In two perianal tumours, in situ or invasive carcinoma developed. Electron microscopy revealed varying degrees of differentiation of keratinocytes. As a result of the defective desmosomes, the tumour cell underwent segregation, with widened intercellular spaces containing oedema, erythrocytes and leucocytes. This phenomenon is probably responsible for frequent bleeding and fistula formation. The investigations disclosed that the Buschke-Loewenstein tumour is a special form of squamous carcinoma and therefore, radical surgical excision must be attempted even in case of a benign histological picture.
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  • 3
    ISSN: 1432-2307
    Keywords: Thrombocytopenic purpura ; Idiopathic thrombocytopenic purpura ; Liver sinusoidal fibrosis ; Electron microscopy ; Immunocytochemistry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary 10 patients with thrombocytopenic purpura (TP) underwent splenectomy. Eight of these patients had idiopathic TP (certain or probable). All had normal liver function tests. Liver histology of the surgical biopsy was normal with the exception of a non specific mild portal infiltration in 6 cases. On Sirius red staining the perisinusoidal network was normal in 3 cases, mildly or moderately increased in 5 cases and often associated with perivenular fibrosis. Collagen types I, III, IV, laminin and fibronectin were increased in the 8 biopsies tested. On semi-thin sections, numerous Kupffer cells were observed. Under the electron microscope, sinusoidal abnormalities were very similar in all 7 patients studied: numerous Kupffer cells containing abundant lysosomes, numerous collagen bundles in the Disse space, active endothelial cells, transformation of some perisinusoidal cells into cells with some of the characteristics of fibroblasts (increased RER) and myofibroblasts (peripheral condensations of the filamentous network), increased fragments of basement membrane-like material. In two cases there was an increase in the number of perisinusoidal cells loaded with lipids. The similarity of the lesions and the absence of other fibrogenic causes (except in 2 cases) suggest that TP may represent another group of diseases with perisinusoidal fibrosis. The aetiology of fibrosis remains unknown but platelet derived growth factor and activated macrophages may play a major role.
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Journal of molecular evolution 26 (1987), S. 347-357 
    ISSN: 1432-1432
    Keywords: Ribosome structure ; Electron microscopy ; Image analysis ; Evolutionary lineages
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Multivariate statistical analysis and classification techniques are powerful tools in sorting noisy electron micrographs of single particles according to their principal features, enabling one to form average images with an enhanced signal-to-noise ratio and a better reproducible resolution. We apply this methodology here to determining the characteristic views of the large (50S) ribosomal subunits from the eubacteriumEscherichia coli and the archaebacteriaMethanococcus vannielii, Sulfolobus solfataricus, andHalobacterium marismortui. Average images were obtained of the subunit in the common crown and kidney projections, but views of the particle in orientations intermediate between these two extremes were also elucidated for all species. These averages show reproducible detail of up to 2.0 nm resolution, thus enabling the visualization and interspecies comparison of many structural features as a first step toward comparing the actual three-dimensional structures. Our results disprove evolutionary lineages recently postulated on the basis of electron microscopical images of ribosomal subunits.
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Journal of molecular medicine 65 (1987), S. 144-146 
    ISSN: 1432-1440
    Keywords: Campylobacter pyloridis ; Duodenal ulcer ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The ultrastructure of campylobacter-like organisms found within duodenal biopsy specimens from 7 of 24 patients (28%) with active duodenal ulcer is described. Their curved shape and variable size are similar to what has previously been reported in descriptions of light microscopies. The organisms were found at the edge of active duodenal ulcers exclusively near neutral-mucous producing antral cells, to which they can adhere. The presence of these bacteria within cells and in the intercellular fluid implies that they can penetrate through the cell membrane or through tight intercellular junctions. The occurrence of these bacteria as well as numerous polymorphonuclear leukocytes in the afflicted regions suggests that the bacteria originally described by Warren and Marshall are indeed pathogenic and that their influence on ulcer healing should be included in designing treatment protocols.
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Archives of toxicology 59 (1987), S. 385-390 
    ISSN: 1432-0738
    Keywords: Lung ; Methyl isocyanate ; Gas poisoning ; Electron microscopy ; Rats
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The static exposure of rats to 0.25 mg/l methyl isocyanate for 1 h resulted in damage to the epithelium of the proximal bronchioles and upper airways. Bronchiolar cells exhibited both nuclear and cytoplasmic damage; many epithelial cells, particularly in the bronchi and trachea, were killed and/or dislodged from the basement membrane. A “raft” of cell debris and fibrin lined most of the airways during the 1st week after exposure but repair to the underlying epithelium was well advanced within 2–3 days. The majority of airways were lined by a normal epithelium within 3 weeks of exposure, but isolated foci of hyperplasia and occluded airways probably accounted for continued respiratory impairment.
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  • 7
    ISSN: 1432-0738
    Keywords: Isopropyl alcohol ; Tracheal mucosa ; Ciliary activity ; Recovery process ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The toxicity of isopropyl alcohol (IPA) on the tracheal mucosa was studied experimentally with special reference to the recovery process of the organ. The results showed that 400 ppm IPA has an acute effect on the mucociliary system in the tracheal mucosa, and that recovery from such degeneration can occur in 2 weeks. When functional and morphological damage was induced by a higher level (5500 ppm) of IPA, recovery did not occur in 2 weeks. The conclusion is that the present allowable level of IPA is reasonable from the viewpoint of the effects of short-term exposure to IPA on the tracheal mucosa. In addition, a higher level of IPA exposure has longer-term effects on the tracheal mucosa, and workers exposed to such a higher level of IPA vapor should be given careful otolaryngological follow-up observations.
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Acta neuropathologica 75 (1987), S. 116-122 
    ISSN: 1432-0533
    Keywords: Rat ; Lead ; Brain edema ; Electron microscopy ; Immunohistochemistry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Newborn rats were exposed to daily intraperitoneal injections of 10 mg lead nitrate per kg body weight for the first 15 postnatal days. The growth and mortality of the lead-exposed animals did not differ from their control litter-mates, injected with vehicle only. In our previous studies, focal hemorrhages and spongy areas as well as breakdown of blood-brain barrier to plasma proteins were shown by light microscopy in the cerebellar parenchyma of 15-day-old rats exposed to this dose. In spite of these signs of edema, measurements of brain tissue specific gravity did not show increased water content. In the present investigation we examined the ultrastructure of the brain lesions in these rats with low-dose lead encephalopathy, focusing on signs of edema, and evaluated astroglial reaction by immunocytochemical staining for glial fibrillary acidic protein (GFAP). The electron microscopic findings were compatible with extracellular edema in the cerebellum of 15-day-old lead exposed rats. The number of GFAP-positive cell bodies in the gray substance of the cerebellar cortex was increased in the 15-day-old lead-exposed rats as compared with the controls of the same age, a finding which is presumably related to the leakage of plasma proteins. Both these findings were lacking at 20 days of age, suggesting reversibility of the lead-induced changes.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1432-0533
    Keywords: Pleomorphic xanthoastrocytoma ; Epithelial properties ; Circumscribed growth ; Electron microscopy ; Immunohistochemistry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Three cases of pleomorphic xanthoastrocytoma (PXA), one of which showed anaplastic evolution, are described. In all three the PXA tumors were well circumscribed and could be totally removed. Light-microscopically, pleomorphic tumor cells clustered gregariously and often formed alveolar structures. Electron microscopy revealed various epithelial properties, such as junctions and interdigitations between apposing tumor cells, and prominent basal laminae surrounding tumor nests. The circumscribed growth of PXA, as contrasted with an infiltrative growth of usual astrocytoma, can be attributed to the cellular cohesion based on the epithelial properties of the tumor cells. In the third patient, tumor recurred 6 months postoperatively. Although the recurrent tumor retained the alveolar structures, pleomorphism and various degenerative features of the tumor cells diminished with advance in the proliferative activities.
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Anatomy and embryology 176 (1987), S. 251-258 
    ISSN: 1432-0568
    Keywords: Decidua ; Involution ; Electron microscopy ; Mouse
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Involution of the antimesometrial decidua was analysed by electron microscopy on days 9, 10 and 11 of pregnancy in the mouse. During this period, the width of the antimesometrial decidua decreases considerably. Involution begins in the decidual cells situated closest to the embryo (internal decidua) and proceeds towards the myometrium. The cells of the internal decidua showed signs of deterioration characterized by accumulation of clumps of chromatin in the nuclei and dilation of the perinuclear cisterna and endoplasmic reticulum cisternae. Autophagosomes and heterophagosomes accumulated in the cytoplasm of these cells. Cells particularly strongly affected became spherical and were devoid of their plasma membrane. Some cells near the trophoblast as well as the mature decidual cells situated farther from the embryo showed a normal morphology. The trophoblastic cells established close contact with healthy decidual cells and engulfed fragments of disorganized decidual cells. It is suggested that the death of decidual cells is a type of programmed cell death and that it is not due to a direct lytic action by the trophoblast.
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  • 11
    Electronic Resource
    Electronic Resource
    Springer
    Archives of dermatological research 279 (1987), S. S30 
    ISSN: 1432-069X
    Keywords: Cicatricial pemphigoid ; Vegetating lesions ; Immunopathology ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A case with widespread vegetating-pustular skin lesions, oral erosions, ulcerations and scarring, and conjunctival synechiae is reported. Clinically, histopathologically, and by immunofluorescence and electron microscopy this patient combined the features of pemphigoid vegetans, as described by Winkelmann and Su, and the mucocutaneous type of cicatricial pemphigoid. This observation suggests that a third subset of cicatricial pemphigoid can now be added to the two existing ones, the mucocutaneous and Brunsting-Perry types, and the designation vegetating cicatricial pemphigoid is proposed for this heretofore undescribed condition.
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  • 12
    Electronic Resource
    Electronic Resource
    Springer
    Acta neuropathologica 73 (1987), S. 370-378 
    ISSN: 1432-0533
    Keywords: Electron microscopy ; Factor VIII ; Glial fibrillary acidic protein ; Hemangioblastoma ; Tissue culture
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The histogenesis of stromal cells in capillary hemangioblastoma has been the subject of debate. The light and electron microscopic studies of hemangioblastomas presented here showed pericytic and leiomyoblastic features in stromal cells. Cells cultured by the monolayer method showed similar features to those of the original tumors. Immunohistochemical studies for glial fibrillary acidic protein and factor VIII/von Willebrand factor indicated that stromal cells were antigenically distinct from astrocytes and endothelial cells. These findings suggest that stromal cells are closely related to pericytes and smooth muscle cells, and support Rhodin's speculation that pericytes serve as a precursor to smooth muscle cells.
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  • 13
    ISSN: 1432-0533
    Keywords: Hypoglycemia ; Rat striatum ; Glutamate ; Excitotoxic nerve cell injury ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary In rat striatum severe hypoglycemia causes an irreversible nerve cell injury, which does not become manifest until during the post-insult recovery period. This injury can be ameliorated by lesions of the glutamatergic cortico-striatal pathway, which suggests that an “excitotoxic” effect mediated by the glutamatergic input is the likely cause of the posthypoglycemic nerve cell destruction. In this paper we further characterize the protective effect of abolishing the glutamatergic innervation to striatum at the ultrastructural level. Two weeks after a unilateral cortical ablation rats were subjected to 30 min of severe hypoglycemia with isoelectric EEG and killed either immediately after the insult or following 60 min of recovery induced by restoring the blood glucose levels. Immediately after the hypoglycemic insult the structure of striatum was similar on both sides (except for the changes attributable to the ablation); i.e., the neurons and their dendrites had pale cytoplasm with condensed mitochondria, sparse RER and pinpoint ribosomes. After 60 min restitution numerous striatal neurons on the non-protected, non-ablated side had turned variably dark and condensed, whereas under-neath the ablation they remained similar as immediately after hypoglycemia. This sequence indicates that the most likely cause of nerve cell destruction on the non-protected side is the “excitotoxic” effect mediated by the glutamatergic innervation, which is superimposed on the action of the hypoglycemic insultper se. Furthermore, the primary condensation of neurons and their dendrites indicate existence of another type of acute “excitotoxic” nerve cell injury which differs from the previously described injury characterized by neuronal swelling.
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  • 14
    Electronic Resource
    Electronic Resource
    Springer
    Acta neuropathologica 75 (1987), S. 131-139 
    ISSN: 1432-0533
    Keywords: Cerebral ischemia ; Hyperglycemia ; Substantia nigra ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Preischemic hyperglycemia induced by feeding or glucose infusion worsens the brain damage and the clinical outcome following ischemia of a given duration and density, and characteristically causes postischemic seizure activity. Light microscopy has previously showed that, in the rat, transient hyperglycemic ischemia induced by bilateral carotid occlusion in combination with arterial hypotension causes a uni- or bilateral lesion in the pars reticulata of the substantia nigra. Since this region has a central role in preventing seizure discharges the present study was carried out to determine the ultrastructural characteristics of this lesion. In rats with 10 min of transient hyperglycemic ischemia followed by recirculation for 1 to 18 h, the pars reticulata of the substantia nigra showed signs of status spongiosus, as well as extensive nerve cell alterations. These changes were observed after all recovery periods studied. The spongiotic appearance was mainly caused by swelling of dendrites and, to a lesser degree, by astrocytic swelling. The dendrites were expanded at all recovery times but the severity increased during the later periods of recirculation. These swollen dendrites contained severely expanded mitochondrias and endoplasmic reticulum. The cytoskeletal elements showed disordered lining of microtubules. Two major types of nerve cell alterations were present: a “pale” and a “dark” variety. The pale type was the most frequent cell alteration. It occurred in all experimental groups and at all time points. Redistribution of the nuclear chromatin and of cytoplasmic organelles as well as swelling of the same type as in the dendrites were the essential changes. The dark neurons were much fewer in number and occupied a peripheral position in the pars reticulata. Astrocytic foot processes appeared to be dilated around the dark neurons. Swelling of astrocyte processes was most pronounced in the 1 h recovery animals. Both types of neurons showed severe mitochondrial alterations of the type observed in dendrites. Occasionally, mitochondrial alterations were found in astrocytic processes as well. Blood vessel alterations were lacking. Previous studies have shown that in this model of ischemia the substantia nigra has a relatively well-preserved blood perfusion. In view of this the extensive histopathological lesions are surprising. We speculate that the lesions primarily involve excitotoxic damage to dendrites, with pronounced lactic acidosis playing a contributory role in causing axonal and glial pathology as well.
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  • 15
    Electronic Resource
    Electronic Resource
    Springer
    Anatomy and embryology 176 (1987), S. 525-530 
    ISSN: 1432-0568
    Keywords: Placenta ; Guinea pig ; Labyrinth ; Syncytiotrophoblast ; Tracers ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The permeability of the materno-fetal barrier in the chorioallantoic placenta was studied in guinea pigs with gestation at term applying a variety of electron-opaque tracers via maternal circulation. None of the tracers tested was seen permeating the syncytiotrophoblast in the materno-fetal direction up to a 20 min interval when the fine structure of the placenta was satisfactorily preserved. The lanthanum chloride, cationized ferritin and horseradish peroxidase bound to the trophoblast surface, apparently due to electrostatic forces more than to specific receptors, and no uptake of these probes was detected in the cytoplasm. Albumin-colloidal gold complex, also used as a tracer, yielded similar results. As reported in other species with more complex syncytiotrophoblastic organization, this layer investing maternal lacunae is a highly selective permability barrier.
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  • 16
    Electronic Resource
    Electronic Resource
    Springer
    Acta neuropathologica 74 (1987), S. 169-178 
    ISSN: 1432-0533
    Keywords: Cerebral gangliocytoma ; Parieto-frontal lobe ; Intracytoplasmic inclusion bodies ; No synapse ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary We report a case of cerebral gangliocytoma (GC) with a variety of unusual structures in the tumor cells. Light microscopically, the tumor consisted of typical ganglion cells, atypical cells which has argyrophilic granules in the cytoplasm, and a few astrocytes. Electron microscopically, the tumor cells showed typical gangliocytic features, which had abundant rough endoplasmic reticula, ribosomes and cored vesicles of 90–150 nm diameter, a few 50-nm-diametered non-cored vesicles, and other common organelles in their cytoplasm. Furthermore, neoplastic ganglion cells contained a variety of abnormal structures, including membranous cytoplasmic bodies (MCB), Zebra bodies (ZB), tubular structures, branched tubular structures (BTS), concentrical laminated bodies and curvilinear bodies (CB). The MCB, ZB and CB resembled those in GM2 gangliosidosis (GMG), and the BTS that in infantile neuroaxonal dystrophy (INAD). Although the significance of these inclusions is still unknown, it is considered that some common mechanism might play a role in the metabolism of both neoplastic neuronal cells and degenerating neurons (GMG and INAD). Synapses could not be observed anywhere despite complete neuronal differentiation of many tumor cells.
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  • 17
    Electronic Resource
    Electronic Resource
    Springer
    Anatomy and embryology 176 (1987), S. 145-154 
    ISSN: 1432-0568
    Keywords: Neurological mutant mice ; ‘Purkinje cell degeneration’ (pcd) ; Weaver ; Neural transplants ; Cerebellum ; Light microscopy ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Embryonic cerebellar grafts from genetically normal donors were implanted into the cerebellomedullary cistern of adult ‘Purkinje cell degeneration’ (pcd) and weaver mutant mice, which are respectively characterized by the selective loss of Purkinje and granule cells. Grafts placed into both mutant recipients exhibited a layered cellular organization reminiscent of the normal cerebellar cortex. Molecular, Purkinje, and granule cell layers were identifiable. Grafted Purkinje cells displayed characteristic cytological features, such as hypolemmal cisterns in association with mitochondria in the perikaryon, and lamellar structures in their axons. The cytological features of granule cell somata in the grafts appeared similar to those of mature granule cells. Electron microscopic examination of the molecular layer of the grafts revealed the presence of parallel fibers, which were not oriented in a parallel fashion; axon terminals of such fibers were often presynaptic to dendritic spines. The number of parallel fibers was markedly reduced in grafts implanted into both mutants compared to the normal cerebellar cortex; however, this phenomenon is commonly seen in cerebellum in tissue culture and in cerebellar transplants into normal hosts. It is concluded, therefore, that the environment of the mutant hosts does not affect the survival of Purkinje or granule cells and that transplantation of solid cerebellar grafts in the neurological mutants studied does not seem to pose any apparent limitations beyond those inherent to the process of cerebellar growth and differentiation outside its normal environment.
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  • 18
    Electronic Resource
    Electronic Resource
    Springer
    Acta neurochirurgica 88 (1987), S. 142-146 
    ISSN: 0942-0940
    Keywords: Electron microscopy ; immunohistochemistry ; pituitary ; rhabdomyosarcoma
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Intracranial extension of rhabdomyosarcoma from the face, nasopharynx or middle ear is rare. A 16-year-old boy presented with deterioration of vision and headache. CT scan revealed a soft tissue mass occupying the sphenoid and ethmoid sinuses, extending to the suprasellar fossa and impinging on the optic chiasm. The tumour, mimicking pituitary carcinoma, was removed by transsphenoidal craniotomy. Morphologic studies, including immunohistochemistry and electron microscopy, revealed that the tumour was a rhabdomyosarcoma. This case stresses the value of immunohistochemical and ultrastructural studies in the diagnosis of tumours occurring in the region of the sella turcica. The origin of this tumour was thought to be the sphenoid or ethmoid sinus. The pituitary gland appeared intact.
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  • 19
    Electronic Resource
    Electronic Resource
    Springer
    Acta neurochirurgica 85 (1987), S. 56-62 
    ISSN: 0942-0940
    Keywords: Electron microscopy ; erythropoietin ; haemangioblastoma ; immunohistochemistry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Immunohistochemical studies for erythropoietin were carried out in six capillary haemangioblastomas, three of which were also studied by electron microscopy. The immunohistochemical studies showed that positively stained cells were scattered in the vicinity of capillaries, and that neither endothelial cells nor stromal cells were stained. In their morphology and distribution, the positively stained cells were identical to mast cells as observed by electron microscopy. In one case, erythropoietin was demonstrated in the cyst fluid of the tumour. These findings suggest that mast cells with abundant secreting granules in haemangioblastomas are capable of producing erythropoietin.
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  • 20
    Electronic Resource
    Electronic Resource
    Springer
    Acta neuropathologica 72 (1987), S. 341-348 
    ISSN: 1432-0533
    Keywords: Carbon disulphide neuropathy ; Pacinian corpuscles ; Denervation and reinnervation ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Adult Wistar rats were exposed to carbon disulphide vapours at a concentration of 2.4 mg/l of air for 5 days a week (6 h a day), and the ultrastructure of Pacinian corpuscles and their nerve supply was investigated after 6 months of exposure. Both degenerative and regenerative changes were observed in sensory axons and the corpuscles. In a sample of corpuscles examined, 30% were denervated and about 60% showed clear signs of reinnervation. Some of the reinnervated corpuscles were supplied by unmyelinated axons. In others, one to three myelinated axons were already found at the nerve entry. The axons branched and formed three to eight terminals in the inner core. Due to continuous intoxication, most regenerated terminals were again undergoing degeneration. In peripheral nerves, the evidence of axonal regeneration has been reported in various toxic distal axonopathies. However, the reinnervation of Pacinian corpuscles has not been described before. It can be expected that reinnervation of Pacinian corpuscles and other end-organs also occurs in other axonopathies, if not during continuous poisoning, then at least after its cessation.
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  • 21
    ISSN: 1432-0983
    Keywords: Electron microscopy ; Replicative intermediates
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Some physicochemical properties of the mitochondrial DNAs (mtDNA) from plants of flax, broad bean and mung bean, and from tissue culture cells of jimson weed, soybean, petunia and tobacco were determined. Circular molecules were observed in electron microscope preparations of each mtDNA. In soybean, petunia, broad bean and mung bean mtDNAs, the circular molecules had a continuous distribution of lengths (ranges between 1 to 36 kb, and 1 to 126 kb), heavily skewed toward smaller molecules. Eighty-six percent of the flax circular molecules were from 27 to 54 kb in size, and 78% of the jimson weed circular molecules were from 4 to 15 kb. Replicative forms of 1.2–1.6 kb circular molecules were observed in electron microscope preparations of broad bean mtDNA.
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  • 22
    Electronic Resource
    Electronic Resource
    Springer
    Archives of dermatological research 279 (1987), S. 167-172 
    ISSN: 1432-069X
    Keywords: Morphometry ; Electron microscopy ; Cytological atypia ; Nevus cells ; Melanoma cells
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Cytological atypia, revealed in the course of routine light microscopy, is considered a valuable indicator of malignancy in melanocytic lesions. A clear definition of the term cytological atypia, however, is lacking. Therefore, by morphometric analysis of ultrathin sections of 11 malignant melanomas (7 invasive, 3 in situ, and 1 lentigo maligna melanoma) and 10 compound nevi, we evaluated the discriminating power of the various facets of cytological atypia, i. e., nuclear area, area of the nucleolus, area of the total cell, and nuclear irregularity. In each case, at least 50 intraepidermal melanocytic cells were examined. The two-sided U-test showed significant differences between intraepidermal nevus and melanoma cells, with regard to the mean values (x) and standard deviations (s) of the nuclear area (x and s, p=0.00011), area of the nucleolus (x, p=0.00043; s, p=0.00011), and area of the total cell (x, p=0.00011; s, p=0.00093). However, only the mean values and standard deviations of the nuclear area allowed a clear distinction in each individual case. The area of the nucleus can be estimated in the course of routine histology. We therefore think that the size and variation of the nuclear area should be considered in the histological differential diagnosis between malignant melanomas and benign nevi.
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  • 23
    Electronic Resource
    Electronic Resource
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    Archives of dermatological research 279 (1987), S. 308-314 
    ISSN: 1432-069X
    Keywords: Congenital cutis laxa ; Collagen synthesis ; Electron microscopy ; Morphometry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A case of congenital cutis laxa (CCL) of unclear mode of inheritance associated with multiple pulmonary artery branch stenosis was extensively investigated to assess possible correlations between clinical, ultrastructural, and biochemical features. Light microscopy revealed that elastic fibers were absent in the papillary dermis, while hypoplastic elsewhere. Transmission electron microscopy showed a poor elastin matrix content in some elastic fibers, variable diameters of collagen fibrils, and abundant glycogen granules in most dermal cells. Measurement of collagen fibril diameters, using an image analyzer, was carried out in the patient and two age- and site-matched controls. A biomodal distribution was found in the upper reticular dermis of the patient. In vitro analysis of collagen in skin fibroblast cultures of the patient showed increased collagen synthesis with a balanced production of type I and type III procollagens. Our study confirms that CCL represents a disorder both of collagen and elastic connective tissue.
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  • 24
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    Experimental brain research 66 (1987), S. 175-184 
    ISSN: 1432-1106
    Keywords: Dorsal column nuclei ; Gracile nucleus ; Inferior olive ; Dorsal accessory olive ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary This study examined the termination pattern within the dorsal accessory subdivision of the cat inferior olive of axons arising from the gracile nucleus. The gracile terminals were labeled by anterograde transport of wheat germ agglutinin complexed to horseradish peroxidase and visualized with tetramethyl benzidine. Gracile terminals were found to contain round synaptic vesicles and form asymmetric synaptic contacts. Of particular interest was the finding that gracile axons, like axons from the spinal cord, terminate primarily outside of synaptic glomeruli. Yet most of the gracile terminals did not synapse on isolated dendritic elements. Rather, the majority contacted distal dendrites which directly contacted other dendritic elements, forming simple complexes termed dendritic thickets. Typically the dendritic thickets were composed of two or three dendrites that received input from more than one round vesicle-containing synaptic terminal. Only one terminal per thicket was labeled by injections in the gracile nucleus. This clustering of pre-and postsynaptic elements within the thickets provides opportunities for many of the same interactions allowed by synaptic glomeruli, in particular divergence and convergence of information.
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  • 25
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    Experimental brain research 67 (1987), S. 380-390 
    ISSN: 1432-1106
    Keywords: Adrenal medulla ; Periaqueductal gray ; Neural implants ; Analgesia ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Recent findings in our laboratory indicate that adrenal medullary grafts produce significant alterations in pain sensitivity. Electron microscopic studies were undertaken to correlate these behavioral changes with the neural interactions of the host and graft tissue in the periaqueductal gray. A striking change found 8 weeks after transplantation is that pronounced myelination has taken place both in the graft and in the host tissue. The new myelin formation in the graft has the typical appearance of PNS myelination and, in the host the appearance of CNS myelination. The endothelial cells of the capillaries in the grafted tissue are attenuated and fenestrated in contrast to those of the surrounding parenchymal tissue of the host. By 8 weeks, the graft becomes heavily encapsulated with collagen, while the host CNS tissue develops layers of glial processes outlining the graft. However, collagen and glial layers apparently do not form an absolute barrier to either cellular or humoral interaction between the host and graft tissue. Chromaffin cells can be found protruding into the host CNS tissue and sometimes forming synapses with presumably the host neuronal processes. Grafted chromaffin cells may participate as both postsynaptic and, less often, as presynaptic components of synaptic junctions. The behavioral relevance of these synaptic contacts is unclear, since similar implants of adrenal medullary tissue into the dorsal spinal cord subarachnoid space, which also induce potent analgesia, do not contain synapses. Thus, it is more likely that behavioral changes are brought about by diffusion of neuroactive substances from grafted chromaffin cells to host receptors.
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  • 26
    ISSN: 1432-1106
    Keywords: Ventral mesencephalic grafts ; Electron microscopy ; Afferent synapses ; Tyrosine hydroxylase immunocytochemistry ; Dopaminergic neurons ; Dopaminergic boutons
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary In adult rats with a unilateral 6-hydroxydopamine-induced lesion of the nigrostriatal dopamine pathway, grafts of embryonic ventral mesencephalon can establish extensive efferent connections with the previously denervated host neostriatum and can compensate for motor and sensorimotor asymmetries induced by the lesion. The object of this study was to examine the afferent synaptic inputs to grafted dopaminergic neurons, implanted into a cortical cavity overlying the previously denervated caudate-putamen, using electron microscopic immunocytochemistry. The dopaminergic neurons of the grafts in the same animals had previously been shown to re-innervate the host neostriatum, to form synaptic connections therein and to attenuate the lesion-induced motor asymmetry that occured in response to amphetamine (Freund et al. 1985). In the light microscope, the grafts were found to contain numerous tyrosine hydroxylase-immunoreactive perikarya, dendrites, axons and axonal swellings which had distinct distributions. In addition axons and axonal swellings that were immunoreactive for either substance P or glutamate decarboxylase were present. Electron microscopic analysis of the boutons contacting tyrosine hydroxylase-immunoreactive neurons in the grafts revealed the presence of at least five distinct types of afferent synaptic boutons based on their immunochemistry, morphology, or types of membrane specialization. One type was itself immunoreactive for tyrosine hydroxylase; such synapses are extremely rare in the intact substantia nigra, none were found in the contralateral substantia nigrae or the substantia nigra of a control rat. Three of the remaining types had ultrastructural features that were similar to synaptic terminals that were immunoreactive for substance P or glutamate decarboxylase. These synapses were similar to the types of synapses found contacting dopaminergic neurons in the substantia nigra contralateral to the graft or the substantia nigra of a control rat. The results demonstrate that, in the absence of the normal extrinsic afferent inputs, the intracortical mesencephalic grafts have a well-developed local synaptic circuitry. It is suggested that local circuit regulation of dopaminergic neurons within the graft may, at least in part, be responsible for the maintenance of a normal or close to normal functional activity.
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  • 27
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    Archives of dermatological research 279 (1987), S. 270-272 
    ISSN: 1432-069X
    Keywords: Atopic eczema ; Hyperlinear palms ; Autosomal dominant ichthyosis vulgaris ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
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  • 28
    ISSN: 1432-2013
    Keywords: Sugar transport ; Electron microscopy ; Chicken cecum and jejunum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We have investigated the possible relation between the phloridzin-sensitive influx of α-methyl-D-glucoside (concentration 5 mmol/l) and the brush border surface area, in chicken isolated enterocytes. The intestinal regions studied were: jejunum and proximal cecum (both with high affinity sugar transport sites), medial cecum (with a low affinity transport system) and distal cecum (which lacks any transport ability). Cell apical surface measured by electron microscopy gave the following results; jejunal cells (0.41 μm2) 〉proximal cecal cells (0.23 μm2)〉medial cecal cells (0.15 μm2)=distal cecal cells (0.14 μm2). This parameter is mainly determined by the length of microvilli. Sugar influx studies showed that the concentration of the substrate in cell water (in mmol/l) was jejunum (7.1)〉proximal cecum (2.9) 〉medial cecum (1.7)〉distal cecum (not different from zero). The decline in influx rate from proximal to distal cecum may be explained both by changes in surface and by the different carriers involved (differentK m). Results of sugar concentration in the distal cecal cells do not correlate with the other segments studied since the substrate enters in these cells by a passive process. It is concluded that the degree of development of microvilli should be taken into account when estimating nutrient transport rates in different intestinal segments.
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  • 29
    ISSN: 1437-160X
    Keywords: Chondrocalcinosis ; Calcium pyrophosphate dihydrate crystals ; Polymorphonuclear leukocyte ; Articular cartilage ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Electron microscopy was used to investigate the characteristics of calcium pyrophosphate dihydrate (CPPD) crystals in chondrocalcinosis (pseudogout syndrome). Crystals in midzone cartilage were frequently seen adjacent to chondrocytes. Great variation in crystal size and shape was observed. Most of the pyrophosphate crystals that had been phagocytosed by polymorphonuclear leukocytes of synovial fluid from patients with acute pseudogout were small (≦1 μm), indicating that small crystals can cause intense inflammation. Large numbers of polymorphonuclear leukocytes became attached to the eroded articular surface and phagocytosed microcrystals. Interaction of polymorphonuclear leukocytes with CPPD crystals in the superficial region of articular cartilage may stimulate the release of inflammatory mediators.
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  • 30
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    Colloid & polymer science 265 (1987), S. 855-859 
    ISSN: 1435-1536
    Keywords: Electron microscopy ; polyethylenemelt ; fine structure ; artifact
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract There are still two opinions on the fine structure of polymer melts and glasses: (a) that the structure is similarly homogeneous to that in lower molecular weight materials and (b) that the structure shows larger short-range order regions (2–20 nm), which consist of bundeled segments of the chain molecules. Whereas opinion a relies more on indirect methods of investigation, opinion b is based mainly on fine granular structures which become visible in electron microscope investigations of surfaces of glassy solidified polymers. Such a fine structure can now be observed directly in a polyethylene melt. However, the structure is exposed as an artifact, so opinion a is supported.
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  • 31
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    Journal of cancer research and clinical oncology 113 (1987), S. 392-399 
    ISSN: 1432-1335
    Keywords: Paget's disease of bone ; Osteosarcoma ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The authors report 12 cases (8 men and 4 women) of sarcomatous degeneration in Paget's bone disease, with an average age of 72.3 years. Sarcomatous degeneration occurred often in polyostotic Paget's disease, and osteitis deformans was seen in 4 cases. Femur and pelvis were the most affected bones. Pain was a constant feature, whereas tumefaction and fracture were less common. Osteolytic lesions were more frequent than condensed or mixed lesions and radiological signs of malignancy were usually found. Seven cases were histologically clasiified as osteogenic sarcoma and 3 cases as fibrosarcoma. Electron microscopy was performed on 2 osteogenic sarcomas and in 1 case revealed microcylindrical inclusion in Pagetic osteoclasts and in multinucleated giant tumor cells, but none in mononucleated tumor cells. The average survival time for the patients in this study was only 4.5 months.
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  • 32
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    European archives of oto-rhino-laryngology and head & neck 243 (1987), S. 361-365 
    ISSN: 1434-4726
    Keywords: Human inner ear ; Congenital anomalies ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary We performed light and electron microscopic studies on the temporal bones of a patient with genetic aplastic deafness, in which the right ear had a Mondini-type defect and the left ear a Michel-type anomaly. The round window of each ear was absent. The stapedial foot plate of the right ear was depressed at its central part and was covered by thin membrane. The course of the internal auditory meatus of the left ear was deviated ventrally. There was total aplasia of the cochlea in the left ear, while that of the right ear showed only three-quarters of a turn. In this ear, three sites of spherical bulging were found and were believed to represent outer hair cells. Other structures of the normal cochlear duct were not present. The modiolus of the left ear was round and dome-shaped, contained sparse nerve fibers and a primitive spiral ganglion. The saccule, utricle and semicircular canals of each ear were missing, so that a common cavity of the vestibular system was present. Several otoliths could be seen under the surface of the membrane covering the common cavity. No sensory cells or their related tissues could be found in either ear.
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  • 33
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    European archives of oto-rhino-laryngology and head & neck 243 (1987), S. 382-386 
    ISSN: 1434-4726
    Keywords: Experimental tympanosclerosis ; Calcium antagonists ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The effect of calcium antagonists in experimental tympanosclerosis following infection with Streptococcus pyogenes and vitamin D3 intoxication has been analyzed in a rat animal model. Compared with untreated animals, calcium antagonists exert a positive effect on the degenerative process and on secondary calcification in the subepithelial layer. This effect could be substantiated planimetrically.
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  • 34
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    European archives of oto-rhino-laryngology and head & neck 244 (1987), S. 180-184 
    ISSN: 1434-4726
    Keywords: Localized laryngeal amyloidosis ; Light microscopy ; Electron microscopy ; Immunohistochemistry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary We performed light and electron microscopic studies in a case of localized supraglottic laryngeal amyloidosis involving a 55-year-old woman. Tissue specimens were stained with hematoxylin and eosin, and alkaline Congo red with or without permanganate (KMnO4) treatment, and were also examined with peroxidase-antiperoxidase immunohistochemistry. Biopsy specimens from the epiglottis showed diffuse replacement of the subepithelial region by amyloid, which showed a typical green birefringence under polarized light. Tissue affinity for Congo red was persistent after the KMnO4 treatment. However, the tissue sections showed a positive reaction only to the anti-P component antibody. Electron microscopic studies revealed some disorders of the plasma cells, suggesting that these cells play an important role in focal production of amyloid fibrils.
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  • 35
    ISSN: 1432-0533
    Keywords: Herpes simplex virus type 2 ; Genital infection ; Avidin-Biotin Method ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Mice were infected by the vaginal route with the MS strain of herpes simplex virus type 2 (HSV-2). Serial vaginal cultures were used to confirm infection and to select mice for this study. Two mice were killed by perfusion on days 2–6 post infection (p.i.) and lumbar and sacral cord with cauda were fixed and embedded for electron microscopy. Semithin Epon-sections were stained for viral antigen using a rabbit anti-HSV-2 antiserum and the Avidin-Biotin (ABC) method. Thin sections from antigen-positive blocks were examined by electron microscopy, and the number and types of infected cells detected by these two methods were compared. A good correlation was found between detection of infected cells by these methods. Infected cells included neurons of dorsal root ganglia and spinal cord, satellite cells of dorsal root ganglia, non-myelinating Schwann cells, astrocytes, oligodendrocytes and arachnoidal cells. Infected cells were first detected in the cauda on day 3 p.i. and in the spinal cord on day 5 p.i. The temporal and spatial distribution of infected cells was consistent with neural spread to and within the CNS. The pathological lesions showed a good correlation with the distribution and number of infected cells and are probably due to a direct virus effect. The similar sensitivity of the Epon-ABC method to electron microscopy in detecting infected cells indicates that this method may have useful applications in both experimental and diagnostic work.
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  • 36
    ISSN: 1432-0533
    Keywords: Cerebral calcification ; Fahr's disease ; Electron microscopy ; Histochemistry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A case of idiopathic nonarteriosclerotic cerebral calcification was studied post mortem by histochemical and scanning and transmission electron microscopic methods. Calcification was found bilaterally in the basal ganglia, cerebral cortex, granular layer and white matter of the cerebellum. Histochemical examination revealed that deposits were composed of a mixture of glycoproteins, mucopolysaccharides, calcium salts and iron. Transmission electron microscopy revealed minute deposits mainly in the cytoplasm of adventitial cells of blood vessels and sometimes in the cytoplasmic processes of glial cells. Scanning electron microscopy showed that some of the spherical and hemispherical bodies, which were formed in the adventitial cells of blood vessels, were connected with filamentous cytoplasmic processes of surrounding cells. Small uncalcified deposits occurring in the cytoplasm of the adventitial cells had subsequently had minerals deposited in them. Some kind of impairment of the pericytes may play an important role at the onset of this disease.
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  • 37
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    Cell Motility and the Cytoskeleton 7 (1987) 
    ISSN: 0886-1544
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
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  • 38
    ISSN: 0886-1544
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: We present a high-resolution electron microscopic study of the sidearms on microtubules and vesicles that are suggested to form the crossbridges which produce the microtubule-based vesicle transport in squid axoplasm. The sidearms were found attached to the surfaces of the anterogradely transported vesicles in the presence of ATP. These sidearms were made of one to three filaments of uniform diameter. Each filament measured 5-6 nm in width and 30-35 nm in length. The filaments in some of the sidearms had splayed apart by pivoting at their base, thereby assuming a “V” shape. The spread configuration illustrated the independence of the individual filaments. The filaments in other sidearms were closely spaced and oriented parallel to each other, a pattern called the compact configuration. In axoplasmic buffer containing AMP-PNP, structures indistinguishable from the filaments of the sidearms on the vesicles were observed attached to microtubules. Pairs of filaments, thought to represent the basic functional unit, were observed attached to adjacent protofilaments of the microtubules by their distal tips. These data support a model of vesicle movement in which a pair of filaments within a sidearm forms two crossbridges and moves a vesicle by “walking” along the protofilaments of the microtubule.
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  • 39
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    Cell Motility and the Cytoskeleton 7 (1987), S. 31-38 
    ISSN: 0886-1544
    Keywords: microtubule assembly ; proleolysis ; Vinca drugs ; Zn2+-induced assembly ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Limited proteolysis of tubulin with subtilisin results in cleavage of both the α and β subunits, releasing small peptides from the C-terminal ends. At 37°C the digested tubulin assembles into polymorphic structures: microtubules with attached ribbons in the presence of GTP, rings in the presence of GDP, and protofilament spirals in the presence of vinblastine. Undigested tubulin does not assemble under these conditions. Rings and Vinca-induced spiral structures are assembled from undigested tubulin only when microtubule-associated proteins, high Mg2+ concentrations, or polycations are present. Thus, cleavage with subtilisin affects assembly in a manner similar to the addition of these agents. It appears that binding of positively charged substances may act by neutralizing the charge on the highly acidic C-terminal regions of the α- and β-subunits, while cleavage with subtilisin produces the same effect by removing these peptides. Undigested and subtilisin-digested tubulin form sheets of protofilaments in the presence of Zn2+, which indicates that the binding sites for the 2-3 Zn2+ ions necessary to induce sheet formation do not reside in the C-terminal regions of the monomers.
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  • 40
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    Cell Motility and the Cytoskeleton 7 (1987), S. 46-53 
    ISSN: 0886-1544
    Keywords: actin filament ; fertilization ; fluorescent labeled phallotoxins ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The distribution of actin filaments in the cortical layer of sea urchin eggs during fertilization has been investigated by light microscopy using fluorescently labeled phallotoxins. The cortical layer of both whole eggs and cortices isolated on a glass surface was examined. In cortices of unfertilized eggs, numerous fluorescent spots were seen, which may correspond to short actin filament cores in microvilli. After insemination, one of the sperm-attaching points on the egg surface first became strongly fluorescent. This fluorescence grew around the point of sperm penetration with the growth of the fertilization cone. Then, the cortical layer of the egg around the fertilization cone became strongly fluorescent and the fluorescence propagated in a wavelike manner over the entire cortex. The mechanism of the propagation of actin polymerization is discussed.
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  • 41
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    Cell Motility and the Cytoskeleton 7 (1987), S. 87-93 
    ISSN: 0886-1544
    Keywords: movement ; flagellar ; beat, flagellar ; stigma ; high-speed microcinematography ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Chlamydomonas cells sucked onto micropipettes were filmed at 500 frames/sec and analyzed as to their forward beating mode. A comparison with freely swimming cells revealed that the flagella of the sucked cells beat in a normal threedimensional manner, with beat frequencies that correspond to those of freely swimming cells. Most beats were synchronous. but not symmetrical; cis- and trans-flagellum appear to beat in a slightly different manner. Some cells beat synchronously throughout, but mostly synchrony was interrupted by a single asynchrony or up to incessant asynchronies, caused by transient accelerations of the trans- (fo-) flagellum. Only rarely did cis- and trans-flagella have different but constant beat frequencies. Helical swimming of Chlamydomonas more likely is due to the beat asymmetries of the two flagella than to differences of beat frequencies. In our records, the stigma is on the inside of the helical swimming path.
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  • 42
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    Cell Motility and the Cytoskeleton 7 (1987), S. 110-115 
    ISSN: 0886-1544
    Keywords: microtubules ; antitubulin ; particle translocalion ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Microtubules have been demonstrated to be a substrate for organelle transport and particle translocation in vitro and in vivo. Subsequent to a previous report of inhibition of axonal transport of exogenous tracers in vivo using antiserum NS-20 against tubulin (Johnston et al: Brain Res. 1986), we now show disruption of particle movement in extruded squid axoplnsm using this unique immunological probe. Using video-enhanced contract-differential interference contrast (AVEC-DIC) microscopy, we examined the properties of particle movement along microtubules and demonstrated that bolh the velocity of particle movement and the numbers of particles moving are decreased in the presence of NS-20 antiserum or NS-20 affinity-purified antibodies but. not in the presence of another antiserum against tubulin. The amount of microtubule substrate does not change in the presence of any of the antisera. In conclusion, we suggest that NS-20 antibodies bind near or at a site on the tubulin molecule which is critical in the mechanism of particle transport, and provide a direct immunological probe to examine the mechanism of microtubule involvement in axonal transport.
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  • 43
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    Cell Motility and the Cytoskeleton 7 (1987), S. 116-128 
    ISSN: 0886-1544
    Keywords: actin filament bundle ; macrociliary cell ; Clenophores ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Macrocilia are thick compound ciliary organlles arising individually from elongated epithelial cells on the lips of beroid ctenophores. A giant wedge-shaped bundle of microfilaments extends 25-30 μm from the base of each macrocilium to the lower end of the cell, terminating at a junction with an underlying smooth muscle cell. The broad end of the microfilament bundle is anchored to the macrocilium by striated rootlet fibers that extend from the basal bodies into the bundle and are linked to the microfilaments by periodic bridges. Fluorescence microscopy of rhodamine-phalloidin stained intact tissue, dissociated macrociliary cells, and Triton/glycerol-isolated bundles shows that the microfilaments contain actin. The microfilaments run generally parallel to the long axis of the bundle but are not highly ordered. Filaments decorated with myosin S1 show a uniform polarity with arrowheads pointing away from the tapered membrane-associated end of the bundle. No variations in bundle length (nor changes in rootlet periodicity) were observed in tissue fixed under conditions of calcium activation. Isolated bundles did not contract in Mg-ATP, even though detached macrocilia underwent reactivated beating and sliding disintegration. Macrocilia arc used to bite through food organisms or transport prey into the stomach. The actin filament bundles probably play a supporting role as a structural linker between macrocilia and subepithelial muscle fibers and may serve as intracellular tendons lo mechanically coordinate the motor activities of macrocilia and muscles during prey ingestion.
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  • 44
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    Cell Motility and the Cytoskeleton 7 (1987), S. 129-137 
    ISSN: 0886-1544
    Keywords: actin mRNA ; sclerotium ; polysomes ; Triton X-100 extraction ; cycloheximide ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Translationally active plasmodia of the syncytial slime mold Physarum polycephalum develop into translationally dormant sclerotia during starvation. Although functional mRNA and ribosomes exist in sclerotia, protein synthesis is suppressed at the level of initiation. To test the possibility that alterations in the cytoskeleton may limit protein synthesis, we have examined the distribution of polysomes and actin mRNA in the cytoskeletal (CSK) and soluble (SOL) fractions of Triton X-100-extracted plasmodia and sclerotia. Most of the polysomes and actin mRNA were located in the CSK of plasmodia, while most of the ribosomes and actin mRNA were located in the SOL of sclerotia. The results suggest that ribosomes and mRNA shift from the CSK to the SOL as protein synthesis is suppressed during starvation. Plasmodia and sclerotia can be induced to accumulate excess polysomes by treatment with low levels of the elongation inhibitor cycloheximide. Treatment of plasmodia with cycloheximide caused excess polysomes to accumulate in the SOL, suggesting that the CSK contains a limited capacity for binding translational components and that the association of polysomes with the cytoskeleton is not required for protein synthesis. Treatment of sclerotia with cycloheximide, however, caused polysomes and actin mRNA to accumulate in the CSK, suggesting that the selcrotial cytoskeleton, although depleted in ribosomes and mRNA, is capable of binding translational components. It is concluded that alterations in the sclerotial cytoskeleton are not involved in translational control.
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  • 45
    ISSN: 0886-1544
    Keywords: calcium ; protein phosphorylation ; TFP ; Triton-extracted model ; ciliary orientation ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: To explore possible roles of calmodulin in Ca2+-induced ciliary reversal, we tested the effects of calmodulin antagonists on Triton-extracted models of Paramecium. In the extracted models prepared by the method of Naitoh and Kaneko [Science 176:523-524, 1972], the Ca2+ -induced ciliary reversal was not inhibited by calmodulin antagonists, trifluoperazine (TFP), or 5-chloro-l-naphthalenesulphone amide (W-7). However, in the presence of adenosine 3′,5′-cyclic mono-phosphate (cAMP), whose concentration is below the one that alters the ciliary direction, TFP inhibited ciliary reversal and the models swam forward at 10-5 M Ca2+. When the washing medium in the preparation of the extracted models was replaced with one containing MgCl2, the extracted model showed sensitivity to calmodulin antagonists without addition of cAMP; at 10-5 M Ca2+, 40 μM TFP or 100 μM W-7 inhibited the ciliary reversal and the models swam forward. Such effect of antagonists was abolished by an inhibitor of cAMP-dependent protein kinase. On the other hand, addition of cAMP enhanced the inhibitory effect of antagonists. These results suggest that calmodulin antagonists act to increase the extent of cAMP-dependent protein phosphorylation that inhibits the Ca2+ -induced ciliary reversal.
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  • 46
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    Cell Motility and the Cytoskeleton 7 (1987) 
    ISSN: 0886-1544
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
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  • 47
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    Cell Motility and the Cytoskeleton 7 (1987), S. 178-186 
    ISSN: 0886-1544
    Keywords: colchicine binding ; tubulin ; immunofluorescence ; PtK2 ; Pk15 ; SV-3T3 cells ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: 2-methoxy-5-(2,3,4-trimethoxyphenyl) 2,4,6-cycloheptatrien-1-one (MTC) is a synthetic colchicine analogue, lacking the B ring of the alkaloid (Fitzgerald: Biochem. Pharmacol. 25:1381-1387, 1976). MTC has been shown to bind reversibly to the colchicine binding site of tubulin and to inhibit microtubule assembly in vitro (Andreu et al: Biochemistry 23:1742-1752, 1984; Bane et al: J. Biol. Chem. 259:7391-7398, 1984). Its action on different cultured cell lines (PtK2, Pk15, and SV-3T3) has now been studied. 0.2 × 10-6 M MTC stopped Pkl5 and SV-3T3 cell growth, inducing an accumulation of mitoses in a few hours. Removal of MTC from the culture medium rapidly restored normal mitotic index and growth rates. Partial depolymerization of the cytoplasmic microtubules of PtK2 cells was observed at concentrations ranging from 2 to 5 × 10-7 M. Maximal microtubule network depolymerization was obtained after 4 h of treatment with 2 to 5 × 10-6 M MTC or at a higher MTC concentration (2 × 10-5 M) for less than 2 h. Removal of 2 × 10-5 M MTC (the highest MTC concentration used) from the culture medium resulted in almost complete microtubule polymerization after 10 min of drug recovery and a normal microtubule network in 20-30 min.MTC constitutes an antimitotic drug directed to the colchicine site. It is water-soluble, shows a fast and reversible action, and may therefore be employed as a convenient tool to study cellular microtubule-dependent functions.
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  • 48
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    Cell Motility and the Cytoskeleton 8 (1987), S. 238-249 
    ISSN: 0886-1544
    Keywords: human lymphoblastoma cells ; microtubule organizing centers ; isolation centrioles ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A procedure adapted from that described by Mitchison and Kirschner [Nature 312:232-237, 1984] was used to isolate centrosomes from human lymphoid cells. High yields of homogeneous centrosomes (60% of the theoretical total, assuming one centrosome per cell) were obtained. Centrosomes were isolated as pairs of centrioles, plus their associated pericentriolar material. Ultrastructural investigation revealed: 1) a link between both centrioles in a centrosome formed by the gathering in of a unique bundle of thin filaments surrounding each centriole; 2) a stereotypic organization of the pericentriolar material, including a rim of constant width at the proximal end of each centriole and a disc of nine satellite arms organized according to a ninefold symmetry at the distal end and; 3) an axial hub in the lumen of each centriole at the distal end surrounded by some ill-defined material.The total protein content was 2 to 3 × 10-2 pg per isolated centrosome, a figure that suggests that the preparations were close to homogeneity. The protein composition was complex but specific, showing proteins ranging from 180 to 300 kD, one prominent band at 130 kD, and a group of proteins between 50 and 65 kD. Actin was also present in centrosome preparations.Functional studies demonstrated that the isolated centrosomes were competent to nucleate microtubules in vitro from purified tubulin in conditions in which spontaneous assembly could not occur. They were also very effective at inducing cleavage when microinjected into unfertilized Xenopus eggs.
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  • 49
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    Cell Motility and the Cytoskeleton 8 (1987), S. 274-283 
    ISSN: 0886-1544
    Keywords: focal contacts ; vimentin filaments ; microtubules ; immunofluorescence ; platinum replicas ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Double immunofluorescence staining of quail embryo fibroblasts with rabbit antibody to vinculin and mouse monoclonal antibody to vimentin revealed a coincidence between fluorescence patterns for cell-substrate focal contacts and intermediate filaments. Most of the vinculin-containing adhesion plaques coincided with the ends of vimentin-positive fibrils.This association was further corroborated by immunoelection microscopic observations of the cytoskeletons of quail and mouse fibroblasts using a platinum replica technique. The intermediate filaments were identified either by direct treatment with antivimentin IgM or by an indirect immunogold staining method.Colcemid treatment of the cells caused a collapse of intermediate filaments and destroyed their association with focal contacts. During the early stages of the colcemid-induced collapse of the intermediate filaments, single vimentin fibrils appeared to retain their association with focal contacts.The possible role of the intermediate filaments in the formation and maintenance of focal contacts is discussed.
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  • 50
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    Cell Motility and the Cytoskeleton 8 (1987), S. 284-291 
    ISSN: 0886-1544
    Keywords: tyrosination ; acetylation ; post-translational modifications ; cytoskeleton ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: We have examined the distribution of acetylated α-tubulin using immunofluorescence microscopy in fibroblastic cells of rat brain meaninges. Meningeal fibroblasts showed heterogenous staining patterns with a monoclonal antibody against acetylated α-tubulin ranging from staining of primary cilia or microtubule-organising centers (MTOCs) alone to extensive microtubule networks. Staining with a broad spectrum anti-α-tubulin monoclonal indicated that all cells possessed cytoplasmic microtubule networks. From double-labeling experiments using an antibody against acetylated α-tubulin (6-11B-1) and antibodies against either tyrosinated or detyrosinated α-tubulin, it was found that acetylated α-tubulin and tyrosinated α-tubulin were often segregated to different microtubules. The microtubules containing acetylated but not tyrosinated α-tubulin were cold stable. Therefore, it appeared that in general meningeal cells possessed two subset of microtubules: One subset contained detyrosinated and acetylated α-tubulin and was cold stable, and the other contained tyrosinated α-tubulin and was cold labile. These results are consistent with the idea that acetylation and detyrosination of α-tubulin are involved in the specification of stable microtubules.
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  • 51
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    Cell Motility and the Cytoskeleton 8 (1987), S. 302-311 
    ISSN: 0886-1544
    Keywords: flagella ; cAMP ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: When demembranted axonemes of Chlamydomonas were reactivated with Mg ATP, the proportion of motile axonemes was significantly increased by the preence of either phosphodiesterase (PDE) or protein inhibitor of cAMP-dependent kinase (PKI). The effect of PDE was cancelled by the addition of cAMP. These findings strongly suggest that the axoneme samples have endogenous cAMP, which can reduce the proportion of motile axonemes via phosphorylation. This inhibitory effect of cAMP on Chlamydomonas axonemes is opposite to its stimulatory effect on the axonemal motility in other organisms so far reported. PKI or PDE activated the motility motility either in the absence of Ca2+, when the axonemes beat with an asymmetric waveform, or in 10-5M Ca2+, when the axonemes beat with a symmetric waveform. This cAMP-dependent regulation of motility was observed with the axonemes from which detergent-soluble material had been removed, indicating that the proteins responsible for the regulation still remained in the axonemes. Preliminary in vitro phosphorylation stdies have implicated two polypetides as candidates for the target protein of cAMP-dependent protein kinase: one with a molecular weight of 270 kD and the other with a much larger molecular weight.
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  • 52
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    Cell Motility and the Cytoskeleton 8 (1987), S. 345-359 
    ISSN: 0886-1544
    Keywords: alpha-actinin ; cytoskeleton ; muscle cells ; nonmuscle cells ; stress fiber ; myofibril ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: This study report the first development of a fluorescently labeled filamin. Smooth muscle was labeled with fluorscent dyes in order to study its interaction with stress fibers and myofibrils, both in living cells and in permeabilized cells. The labeled filamin bounds to the Z bands of isolated cross-striated myofibrils and to the Z bands and intercalated discs in both permeabilized embryonic cardiac myocytes and in frozen sections of adult rat venticle. In permeabilized embryonic chick myotubes, filamin bound to early myotubes but was absent at later stages. In living embryonic chick myotubes, the fluorescently labeled filamin was incorporated into the Z bands of myofibirls during early and late stages of develoment but was absent during an intermediate stages. In living cardiac myocytes, filamin-IAR was incorporated into nascent as well as fully formed sarcomeres throughout develoment. In permeabilized nonmuslce cells, labeled filamin bound to attachment plaques and foci of polygonal networks and to the dense bodies in stress fibers. The periodic bands of filamin in stress fibers had a longer spacing in fibroblasts than in epithelial cells. When injected into living cells, filamin was readily incorporated into stress fibers in a striated pattern. The fluorescent filamin bands were broader in injected cells, however, than they were in permeabilized cells. We have interpreted these results from living and permeabilized cells to mean that native filamin is distributed along the full lengh of the actin filaments in the stress fibers, with a higher concentration present in the dense bodies. A sarcomeric model is presented indicating the position of filamin with respect to other proteins in the stress fibers.
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  • 53
    ISSN: 0886-1544
    Keywords: chemotaxis ; cell motility ; cellular polarity ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Amebae of Dictyostelium discoideum normally chemotax to aggregation centers by assessing the direction of outwardly moving, nondissipating waves of the chemoattractant cAMP. However, D. discoideum amebae can also assess the direction of a relatively stable spatial gradient. We demonstrate that amebae migrating towards the “source” of a stable, spatial gradient move faster, extend fewer pseudopodia, and turn less frequently than amebae migrating away from the “source” in the same spatial gradient. In addition, amebae extend lateral pseudopods in a polarized fashion from the anterior half of the cell, and do so as frequently towards the source as away from the source. However, those formed towards the source more often produce a turn than those formed away from the source. These results suggest that there may be two decision-making systems, one localized in the pseudopods, and one along the entire cell body; they support the suggestion that Dictyostelium amebae may employ a temporal mechanism to assess the direction of a spatial gradient of chemoattractant.
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  • 54
    ISSN: 0886-1544
    Keywords: nuclear migration ; microtubules ; F-actin ; root hairs ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A prominent feature of tip growth in filamentous plant cells is that the nucleus often migrates in step with the tip as it extends. We have studied this long-recognized but unexplained relationship in root hairs of the legume Vicia hirsuta by a variety of microscopic techniques. Using rhodaminyl lysine phallotoxin, and antitubulin antibodies, root hairs are shown to contain axial bundles of F-actin and a complex microtubular system. To the basal side of the nucleus the microtubules are cortical and net axial but in the region between nucleus and tip the arrangement is more complicated. Electron microscopic thin sections demonstrate that internal bundles of microtubles exist in addition to the plasma membrane-associated kind. Computerized deblurring of through-focal series of antitubulin stained hairs clarifies the three-dimensional organization: bundles of endoplasmic microtubules progress from the nuclear region toward the apical dome where they can be seen to fountain out upon the cortex.The relationship between nucleus and tip can be uncoupled with antimicrotubule herbicides. Time lapse video microscopy shows that these agents cause the nucleus to migrate toward the base. This contrary migration can be inhibited by adding cytochalasin D, which fragments the F-actin bundles.It is concluded that microtubules connect the nucleus to the tip but that F-actin is involved in basipetal migration as is known to occur when symbiotic bacteria uncouple the nucleus from the tip.
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  • 55
    ISSN: 0886-1544
    Keywords: capping ; concanavalin A ; glycoprotein ; membrane-cytoskeletal interactions ; thymocyte ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Two major rat thymocyte surface glycoproteins, the leucocyte-common (L-C) antigen and the leucocyte sialoglycoprotein (LSGP), were induced to cap independently, using the specific monoclonal antibodies OX-1 and W3/13, respectively, and an appropriate fluorescently labeled second antibody layer. The caps were subsequently isolated from detergent extracted cells by a procedure involving gentle shearing.TRITC-phalloidin staining of the isolated caps demonstrated the presence of F-actin within these structures, and lectin-affinity staining after fractionation on SDS polyacrylamide gels revealed the presence of a concanavalin A (Con A) binding protein of relative molecular weight (Mr) 205,000, gp205, in both the L-C antigen and LSGP caps, but absent from the detergent-insoluble residue isolated from unchallenged cells. These results suggest that gp205 may be involved in the association of cross-linked glycoproteins with the cytoskeleton during capping.
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  • 56
    ISSN: 0886-1544
    Keywords: vimentin ; hereditary disease ; proteolysis ; serum ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Skin fibroblasts from two siblings with giant axonal neuropathy (GAN) were examined by both biochemical and immunocytochemical studies. The presence of intermediate filaments (IF) characteristic of these cells was affected by the growth conditions. Immediately after plating and during the following 24 hours the majority of the cells contained an IF “bundle”; however, after 4-6 days in culture only a minority of the cells retained this structure. We present evidence that trypsinization but not serum concentration is likely to influence the formation of the “bundle.” The results indicate that the formation of the “bundle” may result from a defective association or relationship between the cytoskeleton and the plasma membrane.
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  • 57
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    Cell Motility and the Cytoskeleton 8 (1987), S. 44-54 
    ISSN: 0886-1544
    Keywords: monoclonal antibody ; phosphoproteins ; basal bodies ; morphogenesis ; Paramecium ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The presence of phosphorylated proteins associated with microtubule organizing centers in tissue culture cells during mitosis has been demonstrated by the use of monoclonal antibodies raised against mitotic HeLa cells [Vandre et al., Proc. Natl. Acad. Sci. U.S.A. 81:4439-4443, 1984]. We report here that in Paramecium two of the mitosis specific antibodies, MPM-1 and MPM-2, decorate throughtout the cell cycle all the microtubule organizing centers (MTOCs) located in the cortex and in the oral apparatus (gullet). Immuno-electron microscopy showed that these antibodies labeled the electron-dense material surrounding basal bodies from which several microtubule networks as well as kinetodesmal fibers originate. During mitosis, these antibodies also stained other cortical cytoskeletal structures, the kinetodesmal fibers (MPM-1 and MPM-2) and the epiplasm (MPM-1). Among the different polypeptides recognized by the antibodies on immunoblots, three major ones of 60, 63, and 116 kDa were found to be common to the cortex (where several thousand ciliary basal bodies are anchored) and the oral apparatus (which comprises several hundred basal bodies around which various arrays of cytoplasmic microtubules are organized). Alkaline phosphatase treatment abolished the immunoreactivity of the polypeptides and the labeling observed by immunofluorescence. These results demonstrate that phosphorylated proteins are associated with all the known active microtubule organizing centers present in the cortex throughout the cell cycle of Paramecium. Furthermore they indicate that in Paramecium phosphorylation of proteins could also be involved in the cell cycle dependent dynamics of cortical cytoskeletal structures other than microtubules.
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  • 58
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    Cell Motility and the Cytoskeleton 8 (1987), S. 68-75 
    ISSN: 0886-1544
    Keywords: dynein ; flagella ; motility ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Mutants with outer dynein arm defects or deficiencies all show a major reduction in beat frequency to about half the normal value; some of these mutants show an additional decrease in sliding velocity associated with reduced shear amplitude and an additional reduction in beat frequency, as well as other more minor modifications of the normal forward mode bending pattern. New mutants (ida98, pf30), which appear to be deficient in a subset of inner dynein arms show a reduction in sliding velocity that is primarily associated with a reduction in shear amplitude, with only a small reduction in beat frequency. These differences in motility phenotype between inner and outer dynein arm mutants suggest that inner and outer dynein arms may have distinct functions. The relatively large decrease in sliding velocity associated with partial loss of inner arms is consistent with earlier observations on pf23, a nonmotile mutant lacking inner arms, suggesting that inner arms may have an essential function in motility. The ability to generate reverse mode bending patterns is retained in some inner or outer dynein arm mutants, but appears to be decreased in those mutants which show reduced shear amplitude for the forward mode bending pattern.
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  • 59
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    Cell Motility and the Cytoskeleton 8 (1987), S. 85-90 
    ISSN: 0886-1544
    Keywords: blue damselfish ; motile iridophore ; microtubule ; colchicine ; EHNA ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Iridophores of the blue damselfish, Chrysiptera cyanea, responded to the sympathetic substance, norepinephrine by a shift towards longer wavelengths of the spectral peak of the light reflected by stacks of light-reflecting platelets (“coloring response”). All antimitotic reagents tested, i.e., colchicine, vinblastine, and podophyllotoxin, inhibited the response reversibly, while an actin inhibitor, cytochalasin B, did not. Erythro-9-[3-(2-hydroxynonyl)]adenine (EHNA), a dynein ATPase inhibitor, also blocked the iridophore response effectively. These results indicate that the tubulin-dynein system may be involved in the motility of iridophores, which is regarded as the simultaneous alteration of the distance between adjacent reflecting platelets within the cells.
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  • 60
    ISSN: 0886-1544
    Keywords: cell motility ; sensory transduction ; slime mold ; pseudopod formation ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: In an aggregation territory of Dictyostelium discoideum, outwardly moving, nondissipating waves of the chemoattractant cAMP sweep across each ameba. At the front of each wave, an ameba experiences an increasing temporal and a positive spatial gradient of cAMP. At the back of a wave, an ameba experiences a decreasing temporal and a negative spatial gradient of cAMP. Employing a perfusion chamber, we have mimicked the temporal dynamics of these waves in the absence of a spatial gradient and demonstrated that the frequency of lateral pseudopod formation and the frequency of turning are dramatically affected by the direction and dynamics of the temporal gradient. In addition, since an ameba will move in a directed fashion up a shallow, nonpulsatile gradient of cAMP, we also mimicked the increasing temporal gradient generated by an ameba moving up a shallow spatial gradient. The frequency of lateral pseudopod formation and the frequency of turning were depressed. Together, these results demonstrate that amebae can assess the direction of a temporal gradient of chemoattractant in the absence of a spatial gradient and alter both the frequency of pseudopod extension and turning, accordingly. Although these results do not rule out the involvement of a spatial mechanism in assessing a spatial gradient, they strongly suggest that the temporal dynamics of a cAMP wave or the temporal gradient generated by an ameba moving through a spatial gradient may play a major role in chemotaxis.
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  • 61
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    Cell Motility and the Cytoskeleton 8 (1987), S. 61-67 
    ISSN: 0886-1544
    Keywords: platelets ; cytoskeleton ; vimentin ; microtubules ; immunofluorescence ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Human and bovine platelets contain a 58,000-dalton vimentinlike protein that cross-reacts with antivimentin antibody. Sodium dodecyl sulfate polyacrylamide gel electrophoresis and Western blots indicate that this protein is present in whole platelet lysates and triton insoluble cytoskeletons. Transmission electron microscopy of platelets reveals an isotropic network of individual intermediate filaments distributed throughout the platelets. High salt, triton extracted, glutaraldehyde and tannic acid fixed platelets reveal 10-nm filaments that can be seen to form a peripheral ring, as well as an isotropic network in the body of the cells. Indirect immunofluorescence of resting and spread platelets demonstrates a circumferential staining pattern close to the cell membrane, with additional fibrillar staining throughout the platelets. Our data suggest that the 58,000-dalton vimentinlike protein may be associated with the microtuble coil and the plasma membrane, and may thus help to maintain the resting platelet's discoid shape.
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  • 62
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    Cell Motility and the Cytoskeleton 8 (1987) 
    ISSN: 0886-1544
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
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  • 63
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    Cell Motility and the Cytoskeleton 8 (1987), S. 76-84 
    ISSN: 0886-1544
    Keywords: flagella ; starfish spermatozoon ; proximal centriole ; bend direction ; bend asymmetry ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Since starfish spermatozoa have spherical heads, it is not easy to determine the topographical relationship of the axoneme to the directions of the flagellar bends, the principal, and the reverse bends as defined by Gibbons and Gibbons [J. Cell. Biol. 1972, 63:970-985]. The demembranated spermatozoa are known to take the quiescent “cane” shape with a sharp principal bend at the proximal region of the flagellum in the presence of high concentration of Ca2+. When such spermatozoa were placed on a grid for electron microscopy, fixed with osmic acid vapor, washed with distilled water, and negatively stained with urany1 acetate, the head of the spermatozoon was disrupted and dispersed disclosing the proximal centriole at at the proximal end of the flagellum. The proximal centriole was always found on the concave side of the “cane” -shaped flagella. Electron microscopy of the serial thin sections of intact and demembranated spermatozoa revealed that the doublet microtobules numbers 5 and 6 were contained in the convex edge of the principal bend.
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  • 64
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    Cell Motility and the Cytoskeleton 8 (1987), S. 227-237 
    ISSN: 0886-1544
    Keywords: Vimentin ; tubulin ; lymphocytes ; stimulation ; mitosis ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: We have used double immunofluorescence and electron microscopy to examine the distribution of tubulin and vimentin during the stimulation of mouse splenic lymphocytes by the mitogen concanavalin A. In unstimulated cells, vimentin forms a filamentous network partially coincident with the radial pattern of microtubules. In stimulated cells, the numbers of microtubules assembled from the centrosome. When these cells enter mitosis, vimentin is arranged into a filamentous cage enclosing the mitotic apparatus. During cytokinesis, the polar centrosomes are observed at a position adjacent to the midbody and vimentin is detected as an aggregate, similar to that seen prior to mitosis, close to the centrosome in each daughter cell. Using several agents, such as colchicine, colcemid, nocodazole, and taxol, which affect microtubule assembly, we have observed that the vimentin system, although closely related spatially to the microtubule complex in lymphocytes, can still reorganize independently as these cells progress through in the cell cycle. Throughout mitogenic stimulation in the continued presence of taxol, microtubules are reorganized into a few thick bundles while the vimentin system undergoes a sequence of rearragements similar to those observed during normal stimulation. These data suggest that vimentin dynamics may be important in the progression of lymphocytes through the cell cycle in response to mitogen.
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  • 65
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    Cell Motility and the Cytoskeleton 7 (1987), S. 198-208 
    ISSN: 0886-1544
    Keywords: high-speed microcinematography ; Hemicentrotus ; primitive response ; ciliary reversal ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Transient ciliary movement during responses to electric stimulation of embryos of the sea urchin, Hemicentrotus pulcherrimus, was analyzed in terms of angular direction with a time resolution of approximately 2 ms with high-speed microcinematography. In the primitive response, which can be induced only in the early stages of development of the embryo, bending transients always started with a short pause in the middle of the effective stroke, irrespective of beat position on stimulation. In the reversal response, induced only in the late stages of development, bending transients occurred with a delay as short as some 10 ms from stimulation, and with a transient sharp deviation from the normal beat before the cilium took the position of the beginning of the recovery stroke of the reversed beat. The delay was significantly shorter at the base than at the tip, suggesting that some form of signal travels along the cilium; the speed was ten times higher than that of propagating bends in the normal beat. These facts indicate that the sensitivity to internal changes resulting from stimulation of the axoneme may vary with development, ciliary beat positions, and regions along the cilium.
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  • 66
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    Cell Motility and the Cytoskeleton 8 (1987), S. 324-332 
    ISSN: 0886-1544
    Keywords: sperm motility ; procaine ; calcium ; cAMP ; flagellum ; epididymis ; TMB-8 ; hyperactivation ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Rat sperm from the cauda epididymis exhibit increased motility, longevity, and a distinct circular pattern of flagellar curvature in response to 5 mM procaine-HCI or 0.1 mM 8-(N, N-diethylamino)-octyl-3,4,5-trimethoxybenzoate (TMB-8), reagents that are thought to play a role in the immobilization of free cellular calcium. Triton X-100-extracted sperm models will exhibit the same pattern of motility and curvature as procaine- or TMB-8-activated cells, but only when calcium is removed by a strong chelating agent, and in the pesence of cAMP (3 μM). Demembranated sperm models produced from epididymal rat sperm are quiescent unless cAMP is added. In these sperm models, the presence or absence of free calcium mediates a transition in flagellar curvature. The increased activity of the procaine-treated intact cells was not accompained by a change in cellular ATP content, nor was ATP availability the limiting factor in the quiescent sperm. Therefore, the increased motility produced by procaine is probably mediated by a fall in free intracellular Ca2+ accompained by a rise in cAMP. Our finding that calcium controls the curvature of sperm flagella may explain altered patterns of flagellar beating, such as the hyperactivated motility that sperm exhibit in the female reproductive tract.
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  • 67
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    Cell Motility and the Cytoskeleton 8 (1987), S. 368-374 
    ISSN: 0886-1544
    Keywords: STEM ; polypeptide composition ; ciliary motility ; dynein molecule ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The Brookhaven scanning transmission electron microscpe (STEM) was used to elucidate the structures and masses of 12S and 19S dynein extracted from bull sperm flagella. The 12S particle was a single globular particle with an average mass of 311 ± 10 kdaltons. The 19S dynein particles consisted of two globular heads joined to a common base. The average mass of the 19S particle was 1.6 ± 0.04 × 106 daltons. Thus, with the exception of the larger mass, the bull sperm 19S dynein molecule resembles the two-headed 21S dynein obtained from sea urchin sperm flagella and the 18S dynein obtained from Chlamydomonas with the possibility of a third head giving rise to the 12S particle. The structure, mass and polypeptide composition of bull sperm flagella dynein is compared with outer arm dyneins previously obtained from Chlamydomonas, Tetrahymena, and sea urchin sperm flagella.
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  • 68
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    Cell Motility and the Cytoskeleton 8 (1987), S. 375-391 
    ISSN: 0886-1544
    Keywords: axoneme ; cilia ; flagella ; reactivation ; ram sperm ; high speed video microscopy ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The flagellar movement of intact ejaculated ram sperm, and of demembranated models reactivated with ATP, has been studied using high-speed, high-resolution video microscopy.Intact sperm attached to the coverslip by their heads had an average beat frequency of 20.9 Hz and an average wave amplitude of 20.2 μm. There was little difference in the beat frequency or waveform of these sperm and sperm swimming freely near the coverslip or captured by their heads with a micropipette and held far from the coverslip, inducationg that the flagellar waveform of ram sperm is relatively resistant to distorition as a result of immobilization of the head or proximity to a surface. The beat envelope was nearly planar as determined by observations of free-swimming sperm and sperm captured by their head and oriented so they were beating either parallel or perpendicular to the plane of focus.The effect of various conditions for demembranation and reactivation of the sperm were examined. Treatment of sperm with 0.2 % Triton X-100 removed most of their plasma membrane. Under optimal conditions, nearly 100 % of the demembranted sperm reactivated at MgATP2- concentrations ranging from ∼4 μM to ∼20 mM. From ∼ 1 mM to ∼ 10 mM MgATP2-, their beat pattern closely resembled that of intact sperm; beat frequency depended on MgATP2- concentration. Percent motility was maximal between pH 7.5 and 8.0 and decreased sharply below pH 7.0 and avove pH 8.5. The addition of 50 μM cAMP to the reactivation medium had no effect on percent motility or the beat pattern and did not accelerate the initiation of movement.
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  • 69
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    Cell Motility and the Cytoskeleton 7 (1987), S. 404-405 
    ISSN: 0886-1544
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
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  • 70
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    Cell Motility and the Cytoskeleton 7 (1987), S. 393-403 
    ISSN: 0886-1544
    Keywords: immunocytochemistry ; phosphorylation ; microtubules ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Immunocytochemistry and polyacrylamide gel electrophoresis have been used to study the distribution of phosphorylated forms of neurofilament antigens in rat brain. Immunostaining of tissue with an antisera produced against phosphatasesensitive domains of the 200-kilodalton (kd) neurofilament polypeptide showed that phosphorylated forms of this polypeptide were present in virtually all axons and certain somata and dendrites of neurons in different brain regions. Immunoblots of whole brain homogenate or a neurofilament preparation from rat revealed that the affinity-purified anti-200-kd sera used to immunostain tissue labeled the neurofilament-associated 200-kd band in a phosphatase-sensitive manner. Fine structural analysis of this immunoreactivity in tissue showed that whenever the labeled organelle could be identified, it was a microtubule. In contrast, immunoblot analysis of twice-cycled microtubules from porcine brain revealed that microtubules in vitro did not possess the 200-kd antigen that was observed in situ. The results suggest that our antibody recognizes a phosphorylated domain on the neurofilament involved in cross-linking neurofilaments and microtubules, and that in vivo, phosphorylated epitopes of the 200-kd neurofilament polypeptide are capable of associating with microtubules.
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  • 71
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    Cell Motility and the Cytoskeleton 8 (1987), S. 1-6 
    ISSN: 0886-1544
    Keywords: actin ; G-protein ; pH ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The addition of propionic acid to rabbit neutrophils causes cell acidification and increases the amount of actin associated with the cytoskeleton. Both responses are rapid, and while the cell acidification is somewhat long-lasting, the increase in cytoskeletal actin is transient. It reaches a maximum value within 15 seconds and then return to the basal level. Unlike fMet-Leu-Phe, however, propionic acid does not cause a rise in the intracellular concentration of free calcium. Pretreatment of the cells with pertusis toxin inhibits the propionic acid-produced increase in cytoskeletal actin but not the decrease in intracellular pH. However, the rate of return to the base line of the cell acidification produced by propionic acid is diminished in cells pretreated with pertussis toxin. On the other hand, both the decrease in intracellular pH and the increase in cytoskeletal actin produced by fMet-Leu-Phe are inhibited by pertussis toxin treatment. The results presented here suggest two important points. First, while cell acidification may trigger directly or indirectly the association of actin with the cytoskeleton, it is certainly not sufficient. Second, a functional guanine-nucleotide regulatory protein is required for stimulated cytoskeletal actin. One or more components of the G-protein and/or their effects on phosphoinositide hydrolysis may increase the number of actin monomers and the availability of preexisting actin filaments to these monomers.
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  • 72
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    Cell Motility and the Cytoskeleton 8 (1987), S. 91-105 
    ISSN: 0886-1544
    Keywords: vinculin ; PDGF ; cell growth ; vascular smooth muscle ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Exposure of porcine vascular smooth muscle cells to platelet-derived growth factor (PDGF; 18-180 ng/ml) but not epidermal growth factor (EGF; 30ng/ml), somatomedin C (SmC; 30 ng/ml), or insulin (10 μM), results in a rapid, reversible, time- and concentration-dependent disapperance of vinculin staining in adhesion plaques; actin-containing stress fibers also become disrupted following exposure of cells to PDGF. Disapperance of vinculin staining from adhesion plaques is also caused by 12-O-tetradecanoyl-phorbol-13-acetate (TPA; 200-400 nM), though the time course of the disapperance of vinculin staining under these conditions takes longer than in cells exposed to PDGF. The PDGF-induced removal of vinculin from adhesion plaques was inhibited in a concentration-dependent fashion by 8-(N, N-diethylamin) octy1-3,4,5-trimethoxybenzoate (TMA-8; 0.25-4 μM) and leupepetin (2-300 μM), and by n-α-rosyl-L-lysine chloromethylketone (TLCK; 100 μM) and trifluoperazine (TFP; 2.5 μM). Addition of PDGF to vascular smooth muscle cells caused a rapid, tranient increase in cytosolic free calcium, from a basal resting level of 146 ± 6.9 nM (SEM, n=62) to 414 ± 34 nM (SEM, n=22) as determined using the calcium-sensitive indicator Fura-2 and Digitized Video Microscopy. This increase in cellular calcium preceded the disappearance of vinculin from adhesion plaques and was partially blocked by pretreatment of cells with TMB-8 but not leupeption. This rise in cytosolic free calcium was found to occur in ∼ 80% of the sample population and dispalyed both spatial and temporal subcellular heterogeneity. Exposure of cells to TPA (100 nM) did not result in a change in cytosolic free calcium. Both PDGF (20 ng/ml) and TPA (100 nM) caused cytosolic alkalinization which occurred after PDGF-induced disruption of vinculin from adhesion plaques, as determined using the pH-sensitive indicator BCECF and Digitized Video Microscopy. PDGF stimulated DNA synthesis and vinculin disruption in a similar dose-dependent fashion. Both could be inhibited by leupeptin or TMB-8. These results suggest that 1) exposure of vascular smooth muscle cells to PDGF is associated with the disruption of vinculin from adhesion plaques, 2) PDGF-induced vinculin disruption is regulated by an increase in cytosolic calcium (but not cytosolic alkalinization), and involves proteolysis; 3) activation of protein kinase C also causes vinculin removal from adhesion plaques but by a calcium-independent mechanism, and 4) the cellular response to PDGF-stimulated increases in cytosolic free calcium is heterogeneous. Our data also suggest that cytosolic vinculin distribution is a sensitive indicator of the response of vascular smooth muslce cells to PDGF.
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  • 73
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    Cell Motility and the Cytoskeleton 8 (1987), S. 118-129 
    ISSN: 0886-1544
    Keywords: cytoskeleton ; actin ; alpha-actin ; vinuclin ; microtubules ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Flurescently labeled heavy mermoyosin, alpha-actinin, and vinculin were used to localize actin, and vinculin, respectively, in permeabilized and living cells during the process of stress fiber reassembly, which occurred when cells were removed from ATP-depleting medium (20 mM sodium azide and 10 mM 2-deoxyglucose). In 80% of the cells recovering from ATP depletion, small, scattered plaques containing actin, alpha-actinin, and vinculin were replaced by long, thin, periodic fibers within 5 minutes of removal of the inhibitors. These nascent stress fibers grew broader as recovery progressed, until they attained the thickness of stress fibers in control cells. In the other 20% of the cells, the scattered plaques aggregated within 5 minutes of reversal, and almost all the actin, alpha-actinin, and vinculin in the cell became localized in one perinuclear aggregate, with a diameter of approximaterly 15-25 μm. As recovery progressed, all aggregates resembled rings, with diameters that increased at about 0.5 μm/minute and grew to as large as 70 μm in some giant cells. As the size of the rings increased, fibers radiated outward from them and sometimes spanned the diamater of te rings. The shape of the cells did not change during this time. By 1 hour after reversal, the rings were no longer present and all cells had networks of stress fibers. Indirect immunofluorescence techniques used to localize tubulin and vimentin indicated that microtubules and intermediate filaments were not constituents of the rings, and the rings were not closely apposed to the substrate, judging from reflection contrast optics. The rapid rearrangement of attachment plaques into a perinuclear aggregate that spreads radially in the cytoplasm occurs at the same speed as fibroblast and chromosomal movement, but is unlike other types of intracytoplasmic motility.
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  • 74
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    Cell Motility and the Cytoskeleton 8 (1987), S. 143-154 
    ISSN: 0886-1544
    Keywords: amphibian egg ; Nile blue stain ; microtubules ; subcortial rotation ; cytoplasmic movement ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The amphibian egg undergoes a 30° rotation of its subcortical contents relative to its surface during the first cell cycle, a displacement of 350 μm in 50 min. This is directly visualized by following the movement of an array of Nile blue (a subcortical stain) spots applied to the egg periphery (Vincent, Oster, and Gerhart: Dev Bio 113:484-500, '86). We have investigated the mechanochemical basis of this unusual cell motility. Subcortical rotation depends on microtubule integrity during its entire course and is insensitive to inhibitors of microfilament assembly. It does not depend on newly synthesized proteins for its operation or timing, and it does not involve calcium-dependent processes. Finally, we show that vegetal fragments of the egg can complete rotation on their own, indicating that mechanochemical components can operate locally in this hemisphere.
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  • 75
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    Cell Motility and the Cytoskeleton 8 (1987), S. 165-173 
    ISSN: 0886-1544
    Keywords: erythrocytes ; brain ; vimentin ; neurofilaments ; desmin ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: We have demonstrated a differential association between two types of spectrin, from erythrocytes and brain, with two types of intermediate filaments, vimentin filaments and neurofilaments. Electron microscopy showed that erythrocyte spectrin promoted the binding of vimentin filaments to red cell inside-out vesicles via lateral associations with the filaments. In vitro binding studies showed that the association of spectrin with vimentin filaments was apparently saturable, increased with temperature, and could be prevented by heat denaturation of the spectrin. Comparisons were made between erythrocyte and brain spectrin binding to both vimentin filaments and neurofilaments. We found that vimentin filaments bound more erythrocyte spectrin than brain spectrin, while neurofilaments bound more brain spectrin than erythrocyte spectrin. Our results show that both erythroid and nonerythroid spectrins are capable of binding to intermediate filaments and that such association may be characterized by differential affinities of the various types of spectrin with the several classes of intermediate filaments present in cells. Our results also suggest a role for both erythroid and nonerythroid spectrins in mediating the association of intermediate filaments with plasma membranes or other cytoskeletal elements.
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  • 76
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    Cell Motility and the Cytoskeleton 8 (1987), S. 174-181 
    ISSN: 0886-1544
    Keywords: evolutionary conservation ; side-arms ; binding sites ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: In this study we have applied microtubule-associated proteins (MAPs) from mammalian brain to both native and reassembled insect ovarian microtubules. Such microtubules, which are normally smooth walled, become decorated with projections similar to those observed when mammalian brain MAPs are added back to assembling or assembled mammalian brain microtubules. The mammalian MAPs were also detected as components of insect microtubules when analyzed by polyacrylamide gel electrophoresis. Our observations suggest that mammalian brain MAPs have common binding sites on microtubules from two widely different sources and indicate the degree of evolutionary conservation of such sites.
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  • 77
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    Cell Motility and the Cytoskeleton 8 (1987), S. 190-191 
    ISSN: 0886-1544
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
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  • 78
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    Cell Motility and the Cytoskeleton 8 (1987), S. 261-273 
    ISSN: 0886-1544
    Keywords: spermatozoa ; flagella ; motility ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The variability of flagellar movement, illustrated by the highly heterogenous nature of the ejaculated sperm population of the ram, was analyzed by the use of a stroboscopic technique and an adapted microphotographic 24 × 36 camera system. The multiple-moving-exposures (MME) records give very distinct successive sequences of the flagellar beats and are particularly suitable for the analysis of bend development and propagation along the tail. With this technique, the parameters of the flagellar bending waves of ejaculated ram sperm have been determined. Most of the sperm have planar flagellar beatings; few are rolling under the conditions of observation. The trajectories of the gametes are mostly linear; nevertheless, some have circular paths. The analysis of bending has been focused on two examples for which the difference in the progressiveness ratio was maximum. The circular pathways for ram spermatozoa are linked to an asymmetry between principal and reverse bend probably induced by differences in wave propagation evidenced along the flagellum. A typical sperm flagellar movement may be related either to the conditions of the observations or to some differences in the maturation process of the sperm.
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  • 79
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    Cell Motility and the Cytoskeleton 8 (1987), S. 250-260 
    ISSN: 0886-1544
    Keywords: time lapse ; neuronal differentiation ; cytoskeleton ; growth cone ; PC12 ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: We report a developmental sequence in the type and frequency of behaviours of neurons differentiating in vitro. We characterised these changes with extensive analysis of time-lapse sequence from both the continuing cell line phenochromocytoma PC12 and primary mixed cell culture of cat and mouse central nervous system. PC12 cells activated by nerve growth factor (NGF) differentiate in a uniform and synchronous manner. This allowed the first quantification of changes in different neuron behaviours during morphogenesis.Shortly after NGF activation, PC12 cells are highly labile in morphology and exhibit a large variety of morphological behaviours. During the first week of differentiation, the frequency of these behaviours declines, and gross morphology becomes more stable. The frequency of neurite initiation after 1 week in NGF is one-seventh what it was after 2 days in NGF. Over the same period, neurite retraction declines to one-third, and somal migration ceases altogether. Growthcone activity does not decline during development. These behaviour changes correlate with published data on the differentiation of the neurite cytoskeleton.A qualitatively similar ontogeny was noted in the differentiation of CNS neurons in mixed cell culture. Major differnces occur in the relative timing of changes in behaviours. Mature, stable morphology is not detected in these cultures until 7 weeks in vitro.
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  • 80
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    Cell Motility and the Cytoskeleton 8 (1987) 
    ISSN: 0886-1544
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
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  • 81
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    Cell Motility and the Cytoskeleton 8 (1987), S. 293-301 
    ISSN: 0886-1544
    Keywords: mitosis ; particle motility ; microtubules ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Observations on living mitoic cells have suggested that material in the spindle moves poleward during mitosis. In order to investigate this movement, sea urchin eggs have been microinjected with 0.25-μm diameter carboxylated fluorescent beads. When fluorescent beads were injected into unfertilized Lytechinus variegatus eggs, no motility was detected. When injected into mitotic cells, beads moved to the spindle poles. Individual beads moved rapidly, in a saltory fashion, and followed generally linear paths. Beads appeared to move along astral fibers, were generally excluded from thespindle proper, and accumulated at the spindle poles. Some dispersion of the beads away from the pole was observed as cells completed mitosis, but the majority of beads retained a polar location. After depolymerization of spindle microtubules with nocodazole, some dispersion of beads into the cytoplasm was also observed. Beads moved along taxol-induced astral microtubules and accumulated at astral centers. These observations reveal that negatively chargedbeads accumulate rapidly at mitotic centers, moving toward the minus end of the microtubules. Neither the bidirectional motility of similar beads in interphase cells nor the plus-end-directed bead motility seen in axons was observed in these mitotic cells.
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  • 82
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    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.
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  • 83
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    Cell Motility and the Cytoskeleton 8 (1987), S. 360-367 
    ISSN: 0886-1544
    Keywords: spindle ; autoantibody ; CREST ; scleroderma ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: An autoantibody that binds an antigen localized to the stembody of dividing cells has been identified in a patient with systemic sclerosis. Initially, this antigen is associated with the surface of the metaphase chromosomes. At the onset of anaphase the antigen becomes preferentially associated with the forming stembodies. This association is maintained as furrowing progresses during telophase and continues after the intercellular bridge is released from the daughter cells during G-1. Immunoblots indicate that the epitope detected by immunoflurorescence is present on a protein with an apparent molecular weight of 38 kD.
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  • 84
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    Cell Motility and the Cytoskeleton 7 (1987), S. 368-380 
    ISSN: 0886-1544
    Keywords: cell motility ; rapid freezing ; cytoskeletal architecture ; immunocytochemistry ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: In this study I describe the ultrastructural distribution of myosin in cortical and subcortical areas of antibody-labelled, quick-frozen fibroblasts. In many cells myosin was present in small variably spaced and sized (0.23-0.39 μm long), nonaligned patches, while in other cells much larger periodically spaced patches of more uniform length (0.27 μm) were found. In all regions of the cytoskeleton myosin was found, primarily on linear bundles of actin filaments running parallel to the cell's long axis.Myosin was absent from single actin filaments, actin Filaments perpendicular to actin bundles aligned with the cell's long axis, and actin filaments, such as geodome vertices and parts of the cortex, which had a complex interwoven appearance. These data indicate that in motile non-muscle cells myosin exerts force only in a unidirectional manner. Recognisable myosin filaments were never observed even in cells incubated either in N-ethylmaleimide or sodium azide. The presence of myosin in, and almost to the very edge of, the cortex suggests that the cellular control of actomyosin based movement is direct and over short-range distances. Large numbers of small cross-linking filaments were found in association with cortical and subcortical actin. Their relationship to myosin and overall actin geometry is discussed.
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  • 85
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    Cell Motility and the Cytoskeleton 7 (1987), S. 347-360 
    ISSN: 0886-1544
    Keywords: cytochalasin ; actin ; microtubules ; immunofluorescence ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Indirect immunofluorescence demonstrated a dramatic reorganization of cytokeratin filaments produced by cytochalasin B (CB) treatment of PtK1 cells. Much of the normal cytokeratin network became arranged into a latticework consisting of bundles of cytokeratin filaments that radiated from, and interconnected, distinct foci, Electron microscopy showed foci to be dense granular regions through which bundles of cytokeratin filaments looped. Composition of the foci included actin, myosin, and alpha-actinin, as shown by labeling with rhodamine phalloidin or specific antisera. Simultaneous treatment with CB and colchicine was not required for lattice formation, but did produce more extensive development than did CB alone. In cells treated only with CB, the microtubule network remained intact, even in regions of extensive lattice formation. These results contrast sharply with those of Knapp et al (J. Cell Biol. 97:1788 [1983b]), who found lattice formation dependent upon simultaneous CB and colchicine treatment. Time-course and dose-response studies of CB treatment showed lattice formation to follow disruption of stress fibers and the concentration of actin into distinct patches that marked the location of lattice foci. Overall results suggest a structural association between microfilaments and cytokeratin filaments that produces the lattice pattern upon CB-induced disruption of stress fibers. Lattice formation was not limited to a specific cell-cycle stage, since G1, G2, and M cells displayed the lattice. Treatment of cells with dihydro-CB and experiments with enucleated cells showed that lattice formation was dependent upon neither the inhibition of sugar transport nor the nuclear extrusion effects of CB.
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    Cell Motility and the Cytoskeleton 8 (1987), S. 312-323 
    ISSN: 0886-1544
    Keywords: plant cytoskeleton ; Chlamydomonas ; anti-IFA ; onion root tip cells ; immunoflurescence ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Four monoclonal antibodies were raised against polypetides present in a highsalt detergent-insoluble fraction from cells of Chlamydomonas reinhardtii. Indirect immunofluorescence microscopy of fibroblasts and epithelial cells grown in culture using these plant antibodies revealed staining arrays identical to those obtained with well characterised antibodies to animal intermediate filaments. Immunoflurescence microscopy of Chlamydomonas with these monoclonal antibodies and a monoclonal antibody that recognises all animal intermediate filaments (anti-IFA) gave a diffuse, patchy cytoplasmic staining pattern. Both the plant antibodies and anti-IFA stained interphase onion root tip cells in a diffuse perinuclear pattern. In metaphase through to telophase, the labelling patterns colocalised with those of microtubules. Labelling of the phragmoplast was also detected but not staining of the preprophase band. On Western blots of various animal cell lines and tissues, all the antibodies labelled known intermediate filament proteins. On Western blots of whole Chlamydomonas proteins, all the antiboides labelled a broad band in the 57,000 Mr range, and three antibodies labelled bands around 66,000 and 140,000 Mr but with varibale intensites. On Western blots of whole onion root tip proteins, all the antibodies labelled 50,0000 Mr (two to three bands) polypetides and a diffuse and around 60,000 Mr and three of the antibodies also labelled several polypeptides in the 90,000-200,000 Mr range. The consistent labelling of these different bands by several different monoclonal antibodies recognising animal intermediate filaments makes these polypetides putative plant intermediate filament proteins.
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    Cell Motility and the Cytoskeleton 7 (1987), S. 39-45 
    ISSN: 0886-1544
    Keywords: divalent metal ions ; lanthanide ions ; calcium contraction ; spasmoneme ; Vorticella ; stalk ; contractile regulation ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The glycerinated stalks of the peritrich ciliate, Vorticella, can contract helically and reversibly on the addition of not only Ca2+ but also other divalent or trivalent cations having ionic radii not far from 1 Å. In order to investigate the stalk contraction quantitatively in the absence of Ca2+-chelators, we developed a method to eliminate contaminating Ca2+ and other metal ions in KC1 and pHbuffer solutions by using a Ca2+-and heavy metal ion-specific ion exchange resin (Eporas MX-2) Thus, it was possible to measure the relationship between the fractional stalk length of Vorticella and the free concentration of alkaline earth metal, transition metal, and lanthanide ions in the 0.1 M KC1 and buffer (pH 6.8) solutions. Among these ions, Ca2+, Nd3+, and Eu3+ (having ionic radii of about 1 Å) had the highest affinity for the contractile element in the spasmoneme. As the concentration of lanthanide ions (except Nd3+ and Eu3+) is increased, the Vorticella stalk contracts abruptly at a threshold level; this means that the Hill's parameter is very high, probably more than 6. The results of these experiments and of the co-mixtures of Ca2+ and Tb3+ suggest that a contractile element in the spasmoneme contains both contractile Ca2+-binding and regulatory Ca2+-binding sites.
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    Cell Motility and the Cytoskeleton 7 (1987), S. 68-77 
    ISSN: 0886-1544
    Keywords: microtubule ; motility ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: In the filamentous green alga Mougeotia, each daughter nucleus formed by mitosis is then rapidly moved along the recently divided daughter cell to the central cleavage developing in the chloroplast. This movement is brought about by a cone-shaped array of microtubules (MTs) that ensheath the daughter nucleus and are focused upon a small region, presumably a microtubule-organising center (MTOC). Movement is completed when the MTOC locates and then resides in the chloroplast cleavage, drawing the nucleus into this position.The mitotic spindle is open with initially broad, ill-defined poles. Anaphase A contributes minimally, if at all, to chromosome separation since the half spindles remain about the same length during anaphase and telophase. Thus, anaphase is accommodated and probably achieved by spindle elongation; the interzonal MTs also generate a rudimentary phragmoplast at the ingrowing cleavage furrow. The persistent polar MTs become directly transformed into the cone-shaped array and initiate nuclear movement during early telophase. Various closely or distantly related green algae show this trait of persistent polar MTs. We conclude that this trait has allowed some species to evolve a motility system based directly on the capabilities of astral MTs, for generating the postmitotic nuclear movement essential for the restoration of the interphase cell organization.
    Additional Material: 10 Ill.
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  • 89
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    Cell Motility and the Cytoskeleton 7 (1987), S. 304-314 
    ISSN: 0886-1544
    Keywords: spectrin-like ; actin-binding protein ; Ca++-regulated ; cytoskeleton ; eggs ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Sea urchin egg spectrin has been purified from a homogenate of unfertilized Strongylocentrotus purpuratus eggs using standard biochemical procedures. SDS-PAGE analysis of the molecule revealed a closely spaced, high molecular weight doublet at 237/234 kDa (present in an equimolar ratio). Rotary shadowed images of egg spectrin revealed a double-stranded, elongate, flexible rod-shaped contour, measuring 210 nm in length and ∼ 4-8 nm in width. Additionally, this molecule is shown to be immunologically related to avian erythroid spectrin, since it cross-reacts with antibodies prepared against the chicken erythrocyte α-spectrin/240 kDa subunit. The interaction of egg spectrin with actin was examined by sedimentation and falling-ball viscometry assays. The binding and cross linking properties of spectrin to actin demonstrate a unique Ca++-sensitive regulation at micromolar Ca++ concentrations. This observation provides new insight into the way Ca++ may regulate spectrin-actin interactions in vitro and further suggests possible structural and modulatory roles for egg spectrin in the developing sea urchin embryo.
    Additional Material: 6 Ill.
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  • 90
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    Cell Motility and the Cytoskeleton 7 (1987), S. 337-346 
    ISSN: 0886-1544
    Keywords: cordycepin ; microtubules ; mitosis ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The nucleoside analogue 3′-deoxyadenosine (cordycepin) arrests dividing cells at the onset of mitosis in prometaphase. The microtubules in the arrested prometaphase cells depolymerize to two small asters. A minimum of 80 μg/ml cordycepin or 20 μg/ml cordycepin in combination with 2 μg/ml of the deaminase inhibitor erythro-9-(2-hydroxy-3-nonyl) adenosine (EHNA) lo inhibit its degradation is required to see these effects. Analysis of cell extracts by high-pressure liquid chromatography indicates that cordycepin enters the cells rapidly and is phosphorylated to 3′-dATP. The intracellular concentration rises almost linearly from 0.7 mM after 15 min to 7 mM by 210 min. Concomitantly the ATP concentration shows a rapid drop from the 4 mM present in controls. However, the direct reduction of ATP levels does not mimic the same rapid effects of cordycepin on the microtubules. In addition, similar effects are not produced by a variety of other adenosine analogues with alterations in the 2′ and 3′ ribose positions. Although other pharmacological reagents arrest cells at the onset of mitosis, cordycepin is unusual because of the collapse of the microtubule networks to two small asters that radiate from the microtubule-organizing center. 3′-dATP can replace the requirement for ATP or GTP in the vitro polymerization of microtubules from microtubule protein: however, at limiting concentrations of nucleotide it requires approximately two times the concentration of 3′-dATP as ATP to support an equivalent level of microtubule polymerization. This suggests that the effects of cordycepin in vivo may be the result of the depletion of cellular ATP pools and the altered ability of 3′dATP to substitute for ATP-dependent reactions. Current experiments are testing this hypothesis.
    Additional Material: 8 Ill.
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  • 91
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    Cell Motility and the Cytoskeleton 8 (1987), S. 155-164 
    ISSN: 0886-1544
    Keywords: cold stability ; cytoskeleton ; depolymerization ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Biochemical studies indicate that axonal tubulin is composed of at least two distinct pools that differ in cold solubility and biochmical composition [Brady et al: J. Cell Biol. 99:1716-1724]. To determine the morphologic correlate of cold-insoluble tubulin, segemnts of rat optic nerves were exposed to a series of in vitro experimental conditions that affect microtubules (MTs), including cold, podophyllotoxin (PT), triflupromazine (TFP), and taxol, and then examined by electron microscopy. Longitudinal sections of control axons showed MTs oriented parallel to the long axis of the axons. Axond exposed to Cold, PT, and TFP showed short segments of MTs in association with cytoskeletal disarray. Morphometric studies were used to distinguish between a simple malorientation of MTs (undulation or zigzags in their course) and the loss of labile segments of MTs, leaving the stable portions behind. The lengths of MT segments were measured in longitudinal sections, and the numbers of MTs were determined in the cross sections. All MT segment-length histograms showed a unimodal distribution. Cold and PT produced a simple shift of the control histogram to the shorter length MTs. In cross sections the numbers of MTs in cold- and PT-exposed axons were significantly decreased, indicating that the presence of short segments of MTs. Taxol, an agent that promotes MT assembly, reversed the cold effect partially and resulted in increases in both MT segment lenght and number. These studies indicate that stable MT segments are portions of longer MTs containing both stable and labile regions. Furthermore, these findings are consistent with the hypothesis that cold-insoluble tubulin functions as a transportable MT-organizing complex in the axon.
    Additional Material: 5 Ill.
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  • 92
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    Cell Motility and the Cytoskeleton 8 (1987), S. 182-189 
    ISSN: 0886-1544
    Keywords: Golgi apparatus ; microtubule-organizing center ; G-glycoprotein ; cytochalasin D ; monensin ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: This paper is concerned with the proposition that the insertion of membrane mass into the leading edge of a motile cell plays a critical role in directed cell migration. We show by immunofluorescence, with cells transfected with a cloned cDNA encoding the G-protein of a temperature-sensitive mutant of vesicular stomatitis virus, that the first cell surface appearance of the G-protein is indeed at the leading edge of the motile cell. Two drugs capable of inhibiting directed cell migration, cytochalasin D and monensin, appear to function independently, the former by affecting the actin cytoskeleton without affecting the polarized insertion of membrane mass into the cell surface and the latter by abrogating membrane mass insertion without affecting the actin cytoskeleton.
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  • 93
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    Cell Motility and the Cytoskeleton 7 (1987), S. 221-234 
    ISSN: 0886-1544
    Keywords: α-cytomatrix ; monoclonal antibodies ; immnuolabeling ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: We have demonstrated the presence of MAP-2 in squirrel fish erythrophores using SDS-PAGE, immunobolt, and immunoprecipitation techniques. The monoclonal antibodies used (AP-9, -13, -14) were raised against distinct antigenic sites on Chinese hamster brain MAP-2. Immunoprecipitation studies demonstrated that all three antibodies bind a 300 K protein found in crude cell extracts and in partially purified MAP fractions isolated from erythrophores of the squirrel fish Holocentrus rufus. Immunofluorescent studies confirmed that the 300 K protein was present in cultured erythrophores. Studies of cells induced to aggregate and disperse their pigment granules revealed that the 300 K protein comigrated with the pigment, suggesting that the 300 K protein may constitute part of the “α-cytomatrix” involved in pigment translocations.
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  • 94
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    Cell Motility and the Cytoskeleton 7 (1987), S. 272-281 
    ISSN: 0886-1544
    Keywords: intranuclear mitosis ; spindle formation ; cell cycle ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Tubulin synthesis in the naturally synchronous plasmodium of Physarum polycephalum is a markedly periodic event restricted to the late G2 period of the cell cycle. Mitosis in the plasmodium is intranuclear, and there are no cytoplasmic microtubules at any stage of the cell cycle. We have combined a biochemical investigation of the synthesis of the plasmodial tubulin isotypes and their participation in the mitotic spindle with a microscopic study (immunofluorescence) of the development of spindle microtubules throughout the cell cycle.We have shown that all four tubulin isotypes identified in the plasmodium (α1, α2, β1 and β2) are present in the mitotic spindle. The stoichiometry of isotype usage in the mitotic spindle generally reflects the overall abundance of isotypes in the plasmodium as a whole: β2 〉 α1 〉 α2 〉 β1. We have also shown that tubulins synthesized in the G2 period of one cell cycle can be incorporated into the spindles of the immediately ensuing mitosis and have sufficient biological longevity to allow participation in the mitotic divisions of future cell cycles. Thus, the phenomenon of periodic tubulin synthesis does not reflect a restricted use of tubulin to the cell cycle in which it was synthesized. The major polymerization of tubulin in the nucleus occurred less than 30 min before metaphase. A novel tubulin-containing structure was, however, present in the nucleus approximately 60 min before metaphase. Polymerized tubulin is rapidly removed from the nucleus following nucleokinesis.
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  • 95
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    Cell Motility and the Cytoskeleton 7 (1987), S. 258-271 
    ISSN: 0886-1544
    Keywords: video and fluorescence microscopy ; saltatory particle movements ; cytoskeleton ; microtubules ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: We recorded live, undifferentiated amebae of Dictynstelium discoideum by video microscopy and analyzed the behavior of cytoplasmic particles and granules. Cytoplasmic streaming and saltatory movements are the two major types of particle movements that occur in interphase amebae. Saltatory movements predominated in an area around the nucleus-associated body (NAB) and many were radial toward or away from it, the velocity being very similar in both directions. Some saltations were simple forward movements, and others were complex to-and-fro movements with as many as seven turnabouts. For a given leg of movement the velocity was not uniform along the path. Small particles (〈 1 μm) moved faster (X = 2.8 μm/s) than large (∼ 1 μm; X = 2.1 μm/s) and very large (〉 1 μm; X = 1.4 μm/s) particles, but the smallest particles were visible only in the running image and could not be analyzed. Ultrastructurally, saltating particles are digestive vacuoles and vesicles of various sizes, appearances, and contents, which are numerous particularly in the vicinity of the NAB. Several lines of evidence pointed to a role of microtubules (MTs) in saltatory particle movements. Composites of particle tracks corresponded closely to MT arrays visualized by immunofluorescence. No saltations occurred in mitotic amebae that lack cytoplasmic MTs, but the movements resumed toward the end of division, concurreduced with the rebuilding of the complex of cytoplasmic MTs. Nocodazole reduced and eventually slopped saltatory movements over a period of 3 h, when aberrant MT patterns were the rule. Saltations in slime mold amebae may be an eye-catching feature of intracellular transport functioning in endo- and exocytosis in the shuffling of vesicles containing factors involved in ameboid movement, and in the transduction of external signals to the cell center.
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  • 96
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    Cell Motility and the Cytoskeleton 7 (1987), S. 291-292 
    ISSN: 0886-1544
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
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  • 97
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    Cell Motility and the Cytoskeleton 7 (1987) 
    ISSN: 0886-1544
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
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  • 98
    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.
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  • 99
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    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 7 (1987), S. i 
    ISSN: 0886-1544
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
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  • 100
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    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 8 (1987), S. 106-117 
    ISSN: 0886-1544
    Keywords: Dictyostelium ; mitosis ; microtubule ; MTOC ; immunoflurescence ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: We applied the “agar-overaly” immunofluorescence techinque (Yumura, S., H. Mori, and Y. Fukui, J. Cell Biol. 99:894-899, 1984) to a semisynchronous culture of Dictyostelium discoideum for studying the organization changes in the microtubule system during mitosis. Using a flurescent DNA dye DAPI (4′,6′ -diamidino-2-phenylindole), chromatin fibers and individual chromosomes were visible in cells prepared by this method, whereby the mitotic phase could be critically evaluated.We found that a rapid shortening of the cytoplasmic microtubules was preceded by a structural dislocation from their organizing centers (MTOCs) in the midprophase, resulting in the transient occurrence of free microtubules in the cytoplasm. Statistic analyses showed that microtubule disassembly in prophase was diphasic. Initially long, wavy microtubules shortened from their distal ends. Following dissociation of their proximal ends from the MTOC, all microtubules initiated rapid disassembly, probably from both ends. During this process, microtubule assembly from the now duplicated spindle pole body (SPB) resumed.This study also revealed novel information on the dynamics of the Dictyostelium mitotic spindle: 1) Half spindles interdigitate in the spindle center, and the extent of interdigition increases coincidentally with the spindle elongation, and 2) during the anaphase to telophase, a subpopulation of spindle microtubules elongates while the rest of the microtubules disasemble very rapidly.Overall this study indicates the presence of elaborate mechanisms responsible for the selective assembly/disassembly of particular microtubule subpopulations in situ.
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