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  • 1985-1989  (14,028)
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  • 1
    Electronic Resource
    Electronic Resource
    Oro-facial dyskinesia and the sub-commissural part of the globus pallidus in the cat: role of acetylcholine and its interaction with GABA (1989)
    Springer
    Psychopharmacology 99 (1989), S. 381-385 
    Details
    ISSN: 1432-2072
    Keywords: Oro-facial dyskinesia ; Globus pallidus ; GABA ; Acetylcholine ; Behaviour ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The possible role of cholinergic mechanisms in the sub-commissural part of the globus pallidus (scGP) in the induction of oro-facial dyskinesia (OFD) was studied in cats. Local injections of the cholinergic agonist carbachol into the scGP elicited tongue protrusions in a dose dependent way (100–1000 ng/0.5 μl). The effect elicited by 1000 ng carbachol was selectively antagonized by the cholinergic antagonist scopolamine (10 μg/0.5 μl); this dose of scopolamine was ineffective when injected alone. The tongue protrusions resulted from both normal and abnormal movements: whereas normal movements simply consisted of protruding the flat tongue, abnormal movements implied a variety of movements, especially curling upwards the lateral side(s) or tip of the tongue inside or outside the oral cavity. The abnormal carbachol-induced tongue protrusions formed part of a syndrome marked by dyskinetic movements of the muscles of the eye, ear and cheek, and were identical to those seen previously after local injections of picrotoxin (250–500 ng). Intra-pallidal injections of the abovementioned dose of scopolamine had no effect on the tongue protrusions induced by local injections of 375 ng picrotoxin. However, local injections of 100 ng muscimol, which was previously found to attenuate significantly the effect of 375 ng picrotoxin and which was ineffective when injected alone, significantly attenuated the tongue protrusions induced by local injections of 1000 ng carbachol. These data suggest that the cholinergic effects are mediated via a GABAergic mechanism, but not vice versa. The results are discussed in view of GABAergic and anticholinergic therapies used in oro-facial dyskinesia.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00445562
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  • 2
    Electronic Resource
    Electronic Resource
    Synaptic potentials induced by postganglionic stimulations in cat bladder parasympathetic neurones (1989)
    Springer
    Pflügers Archiv 414 (1989), S. 235-244 
    Details
    ISSN: 1432-2013
    Keywords: Cat ; Urinary bladder ; Parasympathetic ganglion neurone ; Postganglionic stimulation ; Synaptic potentials
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Intracellular recording techniques were used to examine and compare synaptic potentials evoked by stimulating pre- and postganglionic nerve trunks in cat bladder parasympathetic ganglia. In the 76 ganglion cells exammed, two types of responses were recorded on stimulating the postganglionic nerve: an antidromic action potential (type Post NS1;n=30) or a fast excitatory postsynaptic potential (f-EPSP; type PostNS2;n=46) which resulted in an orthodromic-like action potential. In some of the cells exhibiting a PostNS1 response (n=19), a fast depolarization was superimposed on the antidromic spike. This depolarization was due to the synaptic activation of nicotinic receptors. In many of the cells exhibiting either PostNS1 or PostNS2 responses, repetitive stimulation of the postganglionic nerve induced a slow hyperpolarization. Applying nicotinic (hexamethonium, methonium, 0.5–1 mM), muscarinic (atropine, 1 μM), alpha-adrenergic (phentolamine, 1 μM) and purinergic (caffeine, 0.5–1 mM) receptor antagonists completely inhibited the tetanus-induced slow hyperpolarization in some cells (n=5). In other cells (n=15), a slow hyperpolarization persisted in the presence of these antagonists. These results indicate that stimulation of the postganglionic nerve trunk of cat bladder parasympathetic ganglia can elicit not only an antidromic action potential, but also synaptic potentials which are mediated by the activation of cholinergic (nicotinic and muscarinic), noradrenergic and purinergic receptors, as well as a non-cholinergic, non-alpha-adrenergic and non-purinergic synaptic potential.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00580969
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  • 3
    Electronic Resource
    Electronic Resource
    [3H]ICS 205-930 labels 5-HT3 recognition sites in membranes of cat and rabbit vagus nerve and superior cervical ganglion (1989)
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 340 (1989), S. 396-402 
    Details
    ISSN: 1432-1912
    Keywords: 5-HT3 receptors ; Radioligand binding ; [3H]ICS 205-930 ; Cat ; Rabbit ; Vagus nerve ; Superior cervical ganglion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The binding characteristics of [3H]ICS 205-930, a 5-hydroxytryptamine 5-HT3 receptor antagonist, were investigated in membranes prepared from cat and rabbit vagus nerve (VN) and superior cervical ganglion (SCG). The autoradiographic localisation of 5-HT3 recognition sites was also assessed using [3H]ICS 205-930 in slices from cat medulla oblongata, nodose ganglion and vagus nerve. [3H]ICS 205-930 bound to a homogeneous population of high affinity recognition sites in cat VN: Bmax = 201 ± 43 fmol/mg protein, pKD = 9.26 ± 0.17 and SCG: Bmax = 291 ± 40 fmol/mg, pKD = 9.35 ± 0.80 (n = 3). Competition experiments performed in membranes from cat VN and SCG with agonists and antagonists suggested the presence of a homogeneous population of [3H]ICS 205-930 recognition sites. Competition curves were steep and monophasic and were best fitted by a 1 receptor site model. The following rank order of affinity for [3H]ICS 205-930 binding sites was observed with antagonists: SDZ 206-830 = ICS 205-930 〉 BRL 43694 〉 SDZ 206–792 〉 quipazine 〉 MDL 72222 〉 metoclopramide 〉 mCPP and agonists: 2-methyl-5-HT = 5-HT 〉 phenylbiguanide. A similar profile was observed for a limited series of compounds in rabbit membranes. Drugs acting at 5-HT1, 5-HT2 and dopamine receptors (domperidone, spiperone and metergoline) showed very low affinities for [3H]ICS 205-930 recognition sites. The sites labelled with [3H]ICS 205-930 in vagus nerve and superior cervical ganglion of both species displayed the pharmacological profile of a 5-HT3 receptor. There was a significant correlation between the rank order of affinity of the tested compounds for [3H]ICS 205-930 recognition sites in cat and rabbit membranes and their rank order of affinity for 5-HT3 receptors from neuroblastoma-glioma NG 108-15 cells. Autoradiographic studies suggest that [3H]ICS 205-930 binding sites are present over and around the nodose ganglion cell somata, along certain fibers of the vagus nerve and in the terminal areas of this nerve in the medullar nucleus of the vagus. The present data demonstrate that [3H]ICS 205-930 identifies 5-HT3 receptors in preparations of cat and rabbit vagus nerve and superior cervical ganglion.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00167040
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  • 4
    Electronic Resource
    Electronic Resource
    Carotid occlusion increases the release of endogenous GABA in the nucleus of the solitary tract (1989)
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 340 (1989), S. 764-766 
    Details
    ISSN: 1432-1912
    Keywords: Nucleus of the solitary tract (NTS) ; GABA release ; Carotid occlusion ; Blood pressure ; Push-pull cannula ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary In anaesthetized cats, the nucleus of the solitary tract was bilaterally superfused through push-pull cannulae with artificial cerebrospinal fluid (CSF) and the effect of carotid occlusion on the release of endogenous GABA was investigated. Bilateral carotid occlusion led to a rise in blood pressure which was associated with a very pronounced increase in the release rate of GABA in the nucleus of the solitary tract. The results demonstrate the hypertensive function of GABA in the nucleus of the solitary tract and the importance of GABAergic neurons of this nucleus for the central cardiovascular control.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00169687
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  • 5
    Electronic Resource
    Electronic Resource
    Neurovisceral sphingomyelinosis in a Siamese cat (1989)
    Springer
    Acta neuropathologica 79 (1989), S. 330-332 
    Details
    ISSN: 1432-0533
    Keywords: Sphingomyelinosis ; Neuropathology ; Histochemistry ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary This report presents the clinical, morphological and biochemical findings on an 11-month-old female Siamese cat with neurovisceral sphingomyelinosis. Gross pathological features and histochemical findings are compared with the human disease counterpart and the previously described animal models. Hepatomegaly was observed while splenomegaly was not. Although sphingomyelin in liver and spleen was biochemically elevated, histochemical results in this case were slightly different from those previously recorded in human and feline Niemann-Pick disease. These results suggest that this feline case might be a different type of animal Niemann-Pick disease to that reported previously.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00294670
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  • 6
    Electronic Resource
    Electronic Resource
    The cerebellar nuclear afferent and efferent connections with the lateral reticular nucleus in the cat as studied with retrograde transport of WGA-HRP (1989)
    Springer
    Anatomy and embryology 179 (1989), S. 471-483 
    Details
    ISSN: 1432-0568
    Keywords: Lateral reticular nucleus ; Cerebellar nuclei ; Retrograde transport of WGA-HRP ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The cerebellar nuclear projection from the lateral reticular nucleus (NRL) was studied in 29 cats by means of retrograde axonal transport after implantation of the crystalline wheat germ agglutinin-horseradish peroxidase (WGA-HRP) complex in the cerebellar nuclei. It was confirmed that all the cerebellar nuclei receive afferent fibres from the NRL with the strongest termination in the ipsilateral interposed nuclei. In addition, these experiments give evidence of a previously unrecognized topical pattern in the projection to the interposed nuclei, arranged according to the same principle as in the projection to the immediately overlying cerebellar cortex. Thus, the anterior interposed nucleus receives fibres from all parts of the main NRL, its rostral part especially from laterally situated neurons, while subsequent more caudal parts from more medially situated neurons, while the posterior interposed nucleus receives fibres mainly from the dorsomedial part of the main NRL. The cerebellar nuclear projection to the NRL was investigated in 15 cats using retrograde transport after ventral microiontophoretical ejections of the WGA-HRP complex in the main NRL. The contralateral rostral fastigial nucleus was confirmed as the main origin of this projection, but projecting neurons were, in addition, discovered rostrally in the anterior interposed and dentate nuclei on the same side. No topical differences could be observed following ejections in different parts of the NRL; the majority of the projecting neurons were always concentrated along the ventral and lateral borders of the fastigial nucleus and in the adjacent medial part of the anterior interposed nucleus.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00319590
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  • 7
    Electronic Resource
    Electronic Resource
    Response to rates of luminance change of sustained and transient cells in the cat lateral geniculate nucleus and optic tract (1989)
    Springer
    Experimental brain research 74 (1989), S. 116-130 
    Details
    ISSN: 1432-1106
    Keywords: Lateral geniculate nucleus ; Optic tract ; Sustained cells ; Transient cells ; Temporal luminance modulation ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary We recorded the response of sustained (X) and transient (Y) cells in the cat lateral geniculate nucleus (LGN) and optic tract to a stationary spot while the spot luminance was increased and decreased with a constant rate (linear luminance functions), or modulated sinusoidally. The spot filled the receptive field center, and was surrounded by an annulus of fixed luminance. The LGN X cells seemed to perform a differentiation-like operation in the time domain at slow temporal modulations, giving information about rate of luminance change. To the linear luminance functions the cells responded with a constant firing rate. The on-center cells were activated during increasing luminance, the off-center cells during decreasing luminance. This firing rate increased monotonically with rate of luminance change. To low-frequency sinusoidal modulations the cells had a marked negative phase shift. The response of the LGN Y cells had a transient component shortly after the luminance started to increase (on-center cells) or decrease (off-center cells), followed by a secondary, gradually changing component. The peak of the transient component occurred on average when the response of the X cells increased most rapidly. To low-frequency sinusoidal modulation the average negative phase shift of this peak was twice the average of the X cells. The Y system could accordingly provide information about rate of change in the response of the X system. In the optic tract the X fiber response resembled the LGN X cell response in most respects. The Y fibers had only a weak transient response component, so this component was accentuated in the thalamic relay. Also the sensitivity for rate of luminance change was increased in LGN.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00248285
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  • 8
    Electronic Resource
    Electronic Resource
    Note on the tonotopic organization in the cat medial geniculate body: influence of sampling of units (1989)
    Springer
    Experimental brain research 74 (1989), S. 220-226 
    Details
    ISSN: 1432-1106
    Keywords: Cat ; Medial geniculate body ; Hearing ; Tonotopic organization ; Single unit recording
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The tonotopic organization observed in the present study for the pars lateralis (LV) of the medial geniculate body (MGB) in nitrous oxide anesthetized cats is generally consistent with that previously reported under barbiturate anesthesia. The present data, however, provide evidence for local deviations in characteristic frequency (CF) using appropriate sampling procedures of single units. Although the majority of pairs of units recorded simultaneously with the same microelectrode showed comparable CFs, a few pairs of such neighbouring units displayed CF disparities of up to 1.5 octaves. In addition, some units characterized by an elevated threshold had a CF deviating significantly from the general CF progression observed for the majority of units having low thresholds. This study points out the influence of the sampling procedure on the quality of the tonotopic organization observed in the MGB in addition to a possible effect of the level of anesthesia.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00248295
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  • 9
    Electronic Resource
    Electronic Resource
    Short latency somaesthetic responses in motor cortex, transmitted through the spino-thalamic system, in the cat (1989)
    Springer
    Experimental brain research 75 (1989), S. 639-643 
    Details
    ISSN: 1432-1106
    Keywords: Motor cortex ; Somaesthetic responses ; Spinothalamic system ; Intracellular recording ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Evidence is presented that in the cat, the spinothalamic system contributes to short latency somaesthetic responses in motor cortex efferent cells. Intracellular recordings performed on identified pyramidal tract cells and corticospinal cells show that these cells are still activated and/or inhibited from the periphery after a set of central nervous lesions leaving intact only the ventral half of the spinal cord. The responses were attributed to the spinothalamic system. The ascending system is activated through collaterals of afferent fibres running in the dorsal columns of the spinal cord. This peripheral link to the motor cortex might participate in updating the motor command on the basis of information feedback from the periphery.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00249915
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  • 10
    Electronic Resource
    Electronic Resource
    Unitary characteristics of presumptive cholinergic tegmental neurons during the sleep-waking cycle in freely moving cats (1989)
    Springer
    Experimental brain research 76 (1989), S. 519-529 
    Details
    ISSN: 1432-1106
    Keywords: Pontine tegmentum ; Cholinergic neurons ; Single units ; Sleep-waking states ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A total of 260 neurons were recorded in the rostral pontine tegmentum of freely moving cats during the sleep-waking cycle. Of these, 207 neurons (80%) were located in the dorsal pontine tegmentum containing monoaminergic and choline acetyltransferase (ChAT)-immunoreactive, or cholinergic neurons. In addition to presumably monoaminergic PS-off cells (n = 51) showing a cessation of discharge during paradoxical sleep (PS) and presumably cholinergic PGO-on cells (n = 40) exhibiting a burst of discharge just prior to and during ponto-geniculo-occipital (PGO) waves, we observed tonic (n = 108) and phasic (n = 61) neurons exhibiting, respectively, tonic and phasic patterns of discharge during wakefulness and/or paradoxical sleep. Of 87 tonic cells histologically localized in the dorsal pontine tegmentum rich in cholinergic neurons, 46 cells (53%) were identified as giving rise to ascending projections either to the intralaminar thalamic complex (n = 26) or to the ventrolateral posterior hypothalamus (n = 13) or to both (n = 9). Two types of tonic neurons were distinguished: 1) tonic type I neurons (n = 28), showing a tonic pattern and high rates of discharge during both waking and paradoxical sleep as compaired with slow wave sleep; and 2) tonic type II neurons (n = 20), exhibiting a tonic pattern of discharge highly specific to the periods of paradoxical sleep. Tonic type I neurons were further divided into two subclasses on the basis of discharge rates during waking: a) rapid (Type I-R; n = 17); and b) slow (Type I-S; n = 11) units with a discharge frequency of more than 12 spikes/s or less than 5 spikes/s, respectively. Like monoaminergic PS-off and cholinergic PGO-on cells, both tonic type II and type I-S cells were characterized by a long spike duration (median: 3.3 and 3.5 ms), as well as by a slow conduction velocity (median: 1.8 and 1.7 m/s). In the light of these data, we discuss the possible cholinergic nature and functional significance of these ascending tonic neurons in the generation of neocortical electroencephalographic desynchronization occurring during waking and paradoxical sleep.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00248908
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  • 11
    Electronic Resource
    Electronic Resource
    Modulation of short latency cutaneous excitation in flexor and extensor motoneurons during fictive locomotion in the cat (1989)
    Springer
    Experimental brain research 77 (1989), S. 57-68 
    Details
    ISSN: 1432-1106
    Keywords: Cutaneous EPSPs ; Fictive locomotion ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary We examined modulation of transmission in short-latency, distal hindlimb cutaneous reflex pathways during fictive locomotion in 19 decerebrate cats. Fictive stepping was produced either by electrical stimulation of the mesencephalic locomotor region (MLR) or by administration of Nialamide and 1-DOPA to acutely spinalized animals. Postsynaptic potentials (PSPs) produced by electrical stimulation of low threshold afferents (〈 2.5 times threshold) in the superficial peroneal (SP), sural, saphenous or medial plantar nerves were recorded intracellularly from various extensor (n = 28) and flexor (n = 24) motoneurons and averaged throughout the step cycle, together with voltage responses to intrasomatic constant current pulses (in order to monitor relative cell input resistance). Each motoneuron studied displayed rhythmic background oscillations in membrane potential and correlated variations in input resistance. The average input resistance of extensor motoneurons was lowest during mid-flexion, when the cells were relatively hyperpolarized and silent. Conversely, average input resistance of flexor motoneurons was highest during mid-flexion, when they were depolarized and active. The amplitude of the minimum-latency excitatory components of PSPs produced by cutaneous nerve stimulation were measured from computer averaged records representing six subdivisions of the fictive step cycle. Oligosynaptic EPSP components were consistently modulated only in the superficial peroneal responses in flexor motoneurons, which exhibited enhanced amplitude during the flexion phase. With the other skin nerves tested (sural, saphenous, and plantar), no consistent patterns of modulation were observed during fictive locomotion. We conclude that transmission through some, but not all, oligosynaptic excitatory cutaneous pathways is enhanced by premotoneuronal mechanisms during the flexion phase of fictive stepping in several cat hindlimb motor nuclei. The present results suggest that the patterns of interaction between the locomotor central pattern generator and excitatory cutaneous reflex pathways depend on the source of afferent input and on the identity of the target motoneuron population.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00250567
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  • 12
    Electronic Resource
    Electronic Resource
    Central distributions of the efferent and afferent components of the pharyngeal branches of the vagus and glossopharyngeal nerves: an HRP study in the cat (1989)
    Springer
    Experimental brain research 78 (1989), S. 327-335 
    Details
    ISSN: 1432-1106
    Keywords: Pharyngeal vagus nerve ; Pharyngeal glossopharyngeal nerve ; Nucleus ambiguus ; Retrofacial nucleus ; Lateral reticular formation ; Nucleus of solitary tract ; Alaminar spinal trigeminal nucleus ; Horseradish peroxidase ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The central distributions of efferent and afferent components of the pharyngeal branches of the vagus (PH-X) and glossopharyngeal (PH-IX) nerves in the cat were studied by soaking their central cut ends in a horseradish peroxidase (HRP) solution. HRP-labelled PH-X neurones were distributed ipsilaterally in the rostral part of the nucleus ambiguus (NA) and the retrofacial nucleus (RFN); HRP-labelled PH-IX neurones were found in the ipsilateral RFN and the bulbopontine lateral reticular formation (RF). Vagal pharyngeal neurones constituted a large population of brainstem motoneurones. The population of HRP-labelled glossopharyngeal neurones was divided into two components. Indeed, on the basis of their location and somal morphology, the most ventral cells were identified as cranial motoneurones and those scattered in the lateral RF as parasympathetic preganglionic neurones. Application of HRP to the PH-IX nerve resulted also in the labelling of fibres and terminals in the alaminar spinal trigeminal nucleus and the nucleus of the solitary tract (NTS). The afferent fibres entered the lateral medulla with the glossopharyngeal roots, ran dorsomedially, then turned caudally toward the NTS and the caudal part of the alaminar spinal trigeminal motor (V) nucleus. In the NTS, labelled fibres ran mainly along the solitary tract, projecting to terminals in the dorsal and dorsolateral nuclei of the NTS.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00228904
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  • 13
    Electronic Resource
    Electronic Resource
    Eye movements evoked by microstimulations in the brainstem of the alert cat (1989)
    Springer
    Experimental brain research 77 (1989), S. 94-102 
    Details
    ISSN: 1432-1106
    Keywords: Eye movement ; Brainstem ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary This study maps the eye movements evoked by microstimulations in the medulla of 9 alert cats. Trains of square waves (20 μA amplitude, 0.2 msec duration, 200 Hz) were delivered through glass-covered tungsten microelectrodes (0.5–1 MΩ). Movements of both eyes were recorded by the magnetic field/eye coil technique. Stimulation of the prepositus hypoglossi nucleus (PH) evoked nystagmus with ipsilaterally-directed slow phases followed by after-nystagmus with contralaterally-directed slow phases. Stimulation of the medial vestibular nucleus (MVN) induced nystagmus whose slow phases were more often ipsilaterally-directed but at time contralaterally-directed. At nearly all sites where we stimulated the reticular formation underlying prepositus and vestibular nuclei (from P4.5 to P12), we recorded versional conjugate movements. They were most often ipsilaterally-directed. Some microstimulations in the region of the medial longitudinal fasciculus evoked recentering eye movements: regardless of the initial position of the gaze (to the left as well as to the right), microstimulations given at the same place induced a movement of both eyes toward their neutral position. The amplitude of this movement was proportional to the eccentricity of the pre-stimulation position of the gaze.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00250571
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  • 14
    Electronic Resource
    Electronic Resource
    Pharyngeal motoneurones: respiratory-related activity and responses to laryngeal afferents in the decerebrate cat (1989)
    Springer
    Experimental brain research 78 (1989), S. 336-344 
    Details
    ISSN: 1432-1106
    Keywords: Vagal pharyngeal nerve ; Glossopharyngeal nerve ; Single fibre recordings ; Respiratory-related units ; Superior laryngeal nerve ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary In decerebrate, paralyzed and artificially ventilated cats, we recorded the discharge of 64 motor axons supplying the pharyngeal muscles. Filaments containing motor axons, with discharges related to the respiratory cycle (phrenic nerve activity), were teased from the pharyngeal branches of the vagus and glossopharyngeal nerves. Most units (n = 41) fired only during expiration and exhibited a steady, a decreasing or a late augmenting discharge pattern. These units were found only in vagal filaments. Twenty three units discharged during inspiration and exhibited a steady, a late augmenting or a tonic discharge pattern. The inspiratory-related units were present in both the vagus (n=13) and glossopharyngeal (n=10) nerves. Nineteen of 20 pharyngeal inspiratoryrelated units tested were activated at short latency (range 3.4 to 8.0 ms) by stimulation of afferents in the superior laryngeal nerve (SLN). In 13 of these, such stimulation also suppressed their spontaneous activity. SLN stimulation elicited in all 17 pharyngeal expiratory-related units tested a short latency (range 0 to 8 ms) reduction of activity, followed in 7 units by an increase in activity. SLN stimulation occasionally evoked single or rhythmic multifibre bursts in the vagal pharyngeal filaments. These bursts, involving expiratory-related units, likely correspond to the buccopharyngeal stage of swallowing.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00228905
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  • 15
    Electronic Resource
    Electronic Resource
    Orientation bias of cat retinal ganglion cells: a reassessment (1989)
    Springer
    Experimental brain research 76 (1989), S. 182-186 
    Details
    ISSN: 1432-1106
    Keywords: Retinal ganglion cells ; Orientation bias ; Receptive field centre ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary For cat retinal ganglion cells whose receptive field centres were distributed in specified sections of the left visual field, the deviations of the major axis from the radial, horizontal, and circumferential directions were determined. The percentage of cells with deviations within ± 20° from the radial, horizontal, and circumferential directions were, respectively, 33%, 68%, 16%. In addition, comparison between values of deviation from the horizontal direction for cells located at eccentricities of 10° and 20° from the area centralis showed a statistically significant trend: the bias for the horizontal increased with eccentricity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00253635
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  • 16
    Electronic Resource
    Electronic Resource
    The role of inhibitory processes in the formation of functional properties of neurons in vibrissal projection zone of the cat somatosensory cortex (1989)
    Springer
    Experimental brain research 76 (1989), S. 198-206 
    Details
    ISSN: 1432-1106
    Keywords: Somatosensory cortex ; Directional sensitivity ; GABA inhibition ; Picrotoxin ; Bicuculline ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The role of intracortical inhibitory processes in the formation of neuronal receptive fields in the vibrissal projection zone of the somatosensory cortex was studied. Iontophoretic application of picrotoxin and bicuculline blocks the inhibition and causes the loss of directional sensitivity in neurons. Activation of inhibition by distant glutamate application gives opposite results — neurons become direction sensitive. A dependence was found between spatial location of activated cells and the pattern of changes of their detector properties. Inhibitory processes caused by natural afferent stimulation lead to similar changes in the functional properties of neurons.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00253637
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  • 17
    Electronic Resource
    Electronic Resource
    Quantitative measurements of receptive field changes during antagonism of GABAergic transmission in primary somatosensory cortex of cats (1989)
    Springer
    Experimental brain research 78 (1989), S. 514-532 
    Details
    ISSN: 1432-1106
    Keywords: Bicuculline ; Inhibition ; Latency ; Receptive field profile ; Somatosensory cortex ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary In cortical area 3b of cats, responses of 76 single neurons to punctate indentations were recorded before and during iontophoretic administration of bicuculline methiodide (BMI), a GABAergic antagonist, at levels that did not affect spontaneous activity. Constant amplitude indentations were applied to selected sites along distalproximal and radial-ulnar axes that intersected the most sensitive area in the receptive field. Profiles of response magnitudes were used to measure receptive field dimensions before and during antagonism of GABAergic inhibition. Blockade of GABAergic transmission caused receptive field dimensions of 48 rapidly-adapting neurons to increase an average 141%, or nearly 2.5 times their original size. Analysis of the spatial distribution of inhibition indicated that in-field inhibition was larger than surround inhibition. During BMI administration, response latency was significantly longer for response elicited from the expanded territory than for responses elicited from within the original receptive field, suggesting that receptive field expansion might be mediated by multisynaptic intracortical connections. The magnitude of receptive field expansion was independent of receptive field size or peripheral location. In a substantial number of neurons, however, BMI produced asymmetric expansions that extended only in the proximal direction. For 9 slowly-adapting neurons, BMI produced measureable increases in receptive field dimensions, but these changes were significantly smaller than the changes in rapidly-adapting neurons.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00230239
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  • 18
    Electronic Resource
    Electronic Resource
    The effects of postsynaptic inhibition on the monosynaptic reflex of the cat at different levels of motoneuron pool activity (1989)
    Springer
    Experimental brain research 77 (1989), S. 577-584 
    Details
    ISSN: 1432-1106
    Keywords: Motoneuron pool ; Inhibition ; Monosynaptic reflex ; Recruitment level ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The motoneurons to the Soleus muscle in the decerebrate cat were activated by the crossed extensor reflex, elicited by stimulation of the contralateral common peroneal (CP) nerve. Monosynaptic reflexes were obtained from the Soleus motoneuron pool by stimulation of the cut L7-S1 dorsal roots. The amplitude of the reflex increased approximately linearly with the recruitment level of the motoneuron pool. Tonic postsynaptic inhibition was induced in the Soleus moto-neuron pool by repetitive antidromic stimulation of the Lateral Gastrocnemius (LG) and Medial Gastrocnemius (MG) nerves at a rate of 17–47 stimuli/s. This reduced the size of the monosynaptic reflex at rest by at least 40%. However, when the motoneurons were active, the amplitude of the monosynaptic reflex obtained during repetitive stimulation of the LG-MG nerve increased with the recruitment level along the same curve as the control reflexes. Thus, tonic postsynaptic inhibition of the motoneurons per se cannot control the amplitude of the monosynaptic reflex independently of the recruitment level of the motoneuron pool. These experimental results verify predictions from computer simulations and suggest by exclusion that presynaptic inhibition is needed to control the amplitude of the monosynaptic reflex independently of the recruitment level of the motor pool.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00249610
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  • 19
    Electronic Resource
    Electronic Resource
    Intercostal and abdominal muscle afferent influence on caudal medullary expiratory neurons that drive abdominal muscles (1989)
    Springer
    Experimental brain research 78 (1989), S. 219-222 
    Details
    ISSN: 1432-1106
    Keywords: Control of respiration ; Intercostal muscle afferents ; Phrenic nerve ; Abdominal muscle afferents ; Expiratory neurons ; Abdominal muscle control ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Our objective was to determine if caudal ventral respiratory group (VRG) expiratory (E) neurons that drive abdominal expiratory motoneurons in the lumbar cord respond to intercostal and lumbar nerve afferent stimulation. Results showed that 92% of medullary E-neurons that were antidromically activated from the upper lumbar cord reduced their activity in response to stimulation of external and internal intercostal and lumbar nerve afferents. We conclude that afferent information from intercostal and abdominal muscle tendon organs has an inhibitory effect on caudal VRG E-neurons that drive abdominal expiratory motoneurons.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00230702
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  • 20
    Electronic Resource
    Electronic Resource
    Behavioural thermosensitivity after bilateral lesions of the lateral funiculi in the cervical spinal cord of the cat (1989)
    Springer
    Experimental brain research 78 (1989), S. 374-379 
    Details
    ISSN: 1432-1106
    Keywords: Thermosensitivity ; Spinal cord ; Ascending pathways ; Behaviour ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The behavioural thermosensitivity of six cats was measured before and after single stage, symmetrical, bilateral, surgical lesions of the cervical spinal cord. The lesions were aimed at an area in the most ventral parts of the dorsal halves of the lateral funiculi. Unilateral lesions of that area have previously been found to cause reproducible, although subtotal, contralateral thermosensory defects, which were attributed to interruption of the thermosensory spinothalamic pathway. The lesions of three of the present cats were found to be incomplete, and those animals showed no postoperative thermosensory deficiency. Two of the cats with complete lesions showed marked post-operative defects, especially immediately after the operations, but the third cat with a complete lesion showed no postoperative thermosensory defect at all. The differences between the last three animals have been compared to the irregularity of previous reports about thermosensitivity after spinal cord lesions in man and animals, and may depend on the testing technique, rather than differences of thermosensitivity per se.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00228909
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  • 21
    Electronic Resource
    Electronic Resource
    The distribution of intrinsic cortical axons in area 3b of cat primary somatosensory cortex (1989)
    Springer
    Experimental brain research 78 (1989), S. 501-513 
    Details
    ISSN: 1432-1106
    Keywords: Somatosensory cortex ; Interlaminar ; Corticortical ; SI ; Area 3b ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The morphology of single neurons in area 3b of cat primary somatosensory (SI) cortex was examined after horseradish peroxidase (HRP) injections. Neurons were labeled either by intracellular injection of HRP following intracellular recording or by small extracellular iontophoretic HRP injections. Both pyramidal and nonpyramidal neurons were labeled and reconstructed from serial sections. Their axons had local, interlaminar and interareal patterns of termination. Most neurons formed local axonal fields around their cell bodies and dendrites. Pyramidal neurons in cortical layer IV sent axons up into layers II and III, neurons in layers II and III sent axons down to layer V, and layer V neurons sent axons to layer VI as well as back to the upper layers. Layer VI neurons sent axons back to the upper cortical layers in a unique bowl-shaped pattern. The horizontal distribution of axons of pyramidal cells in layer III was extremely widespread. Axons of layer III neurons in area 3b terminated within 3b and area 1, but not in other areas of SI. Layer III neurons in area 1 distributed axon collaterals to all fields of SI as well as projecting a main axon to motor cortex. In general, the axon collaterals of area 3b pyramidal cells outside layer III remained confined to area 3b. Most of the nonpyramidal neurons labeled were basket cells in layers III and VI. These neurons formed dense axonal fields around their cell bodies, and none of their axons could be followed into the underlying white matter. The results of the present study demonstrate that area 3b somatosensory cortical neurons and their axons are vertically organized in a manner similar to that reported for other sensory cortical areas. They also show that widespread horizontal connections are formed by pyramidal neurons of layer III, and that these horizontal axons can travel for great distances in the cortical grey matter.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00230238
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  • 22
    Electronic Resource
    Electronic Resource
    Excitatory interactions between phrenic motoneurons: intracellular study in the cat (1989)
    Springer
    Experimental brain research 74 (1989), S. 131-138 
    Details
    ISSN: 1432-1106
    Keywords: Phrenic motoneurons ; Intracellular recording ; Interactions ; Recurrent EPSPs ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary 1. Intracellular recordings were made from 220 Phrenic Motoneurons (PM) in anaesthetized, spontaneously breathing cats, deafferented from C3 to C7, in order to look for somatic events related to the Recurrent Responses (RR) evoked in PM axons by repetitive stimulation of the phrenic nerve. RR appear sporadically at a constant latency, originate from a spinal nicotinic mechanism and can be evoked in a PM without the presence of an antidromic volley in its axon (Khatib et al. 1986). 2. Using stimuli effective for eliciting RR in axons, we failed to observe intracellularly somatic events corresponding to RR after the occurence of an antidromic action potential. RR were observed extracellularly in two cases, but in both cases the recording originated from axons. 3. We attempted to elicit somatic RR without a preceding antidromic action potential, using either parathreshold stimulation of the impaled PM, or suprathreshold stimulation of a phrenic strand which excluded the axon of the impaled PM. In both cases, RR-like events, with very stable latencies, appeared sporadically in 4/142 and 2/15 PMs respectively. 4. Parathreshold stimuli or stimulation of a strand were coupled with averaging of the synaptic noise in order to look for small events temporally related to the stimuli. Short latency small depolarizations, looking-like recurrent EPSPs, were revealed in 22/142 and 5/15 PMs respectively. 5. These results confirm the existence of interrelations between PMs, providing for re-excitation and coupling within the phrenic pool, in addition to centrally imposed synchronization.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00248286
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  • 23
    Electronic Resource
    Electronic Resource
    Binocular depth perception, visual acuity and visual fields in cats following neonatal section of the optic chiasm (1989)
    Springer
    Experimental brain research 74 (1989), S. 272-278 
    Details
    ISSN: 1432-1106
    Keywords: Cat ; Corpus callosum ; Optic chiasm ; Stereoacuity ; Visual acuity ; Visual fields
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary We studied the role of the transcallosal pathway in stereopsis by measuring binocular and monocular depth perception in two cats that had undergone section of the optic chiasm at the age of 21 d. To ensure that the surgery did not impair vision to the extent that depth perception could not be evaluated, visual acuity and visual fields were also measured. In both of the chiasm-sectioned animals the visual fields were reduced and the visual acuity was substantially lower than in normal cats, with a maximum of about 2 cyc deg-1. Binocular depth thresholds of the chiasm-sectioned cats were worse than those of the normal cat but were better than their own monocular thresholds. These results suggest that the chiasm-sectioned animals were still able to use binocular cues to judge depth and indicate that the indirect pathway through the corpus callosum is sufficient to mediate binocular depth perception.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00248860
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  • 24
    Electronic Resource
    Electronic Resource
    Demonstration of axonal branching of fibres from certain precerebellar nuclei to the cerebellar cortex and nuclei: a retrograde fluorescent double-labelling study in the cat (1989)
    Springer
    Experimental brain research 75 (1989), S. 15-27 
    Details
    ISSN: 1432-1106
    Keywords: Precerebellar nuclei ; Cerebellar cortex and nuclei ; Fluoro-Gold ; Rhodamine-B-isothiocyanate (RITC) ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The projections from certain brain stem precerebellar nuclei to the cerebellar cortex and nuclei have been examined in the cat by using the retrograde fluorescent double-labelling technique. Crystalline Fluoro-Gold was implanted into the left cerebellar nuclei from the contralateral side and rhodamine-B-isothiocyanate was injected into the overlying cerebellar cortex. The inferior olive, the lateral reticular nucleus, and the reticular tegmental pontine nucleus all contained double- as well as single-labelled neurons, and it was concluded that these nuclei have a high number of neurons whose axons branch to both the cerebellar cortex and nuclei. The neurons in the paramedian reticular nucleus and the pontine nuclei proper appear to project only to the cerebellar cortex.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00248525
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  • 25
    Electronic Resource
    Electronic Resource
    Projections from the rostral mesencephalic reticular formation to the spinal cord (1989)
    Springer
    Experimental brain research 75 (1989), S. 265-279 
    Details
    ISSN: 1432-1106
    Keywords: Rostral interstitial nucleus of the MLF ; Interstitial nucleus of Cajal ; Spinal cord ; Motoneurons ; Neck muscles ; Axial muscles ; Vertical eye and head movements ; Autoradiography ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Eye and head movements are strongly interconnected, because they both play an important role in accurately determining the direction of the visual field. The rostral brainstem includes two areas which contain neurons that participate in the control of both movement and position of the head and eyes. These regions are the caudal third of Field H of Forel, including the rostral interstitial nucleus of the medial longitudinal fasciculus (riMLF) and the interstitial nucleus of Cajal with adjacent reticular formation (INC-RF). Lesions in the caudal Field H of Forel in monkey and man result in vertical gaze paralysis. Head tilt to the opposite side and inability to maintain vertical eye position follow lesions in the INC-RF in cat and monkey. Projections from these areas to extraocular motoneurons has previously been observed. We reported a study of the location of neurons in Field H of Forel and INC-RF that project to spinal cord in cat. The distribution of these fiber projections to the spinal cord are described. The results indicate that: 1. Unlike the neurons projecting to the extra-ocular muscle motoneurons, the major portion of the spinally projecting neurons are not located in the riMLF or INC proper but in adjacent areas, i.e. the ventral and lateral parts of the caudal third of the Field H of Forel and in the INCRF. A few neurons were also found in the nucleus of the posterior commissure and ventrally adjoining reticular formation. 2. Neurons in caudal Field H of Forel project, via the ventral part of the ventral funiculus, to the lateral part of the upper cervical ventral horn. This area includes the laterally located motoneuronal cell groups, innervating cleidomastoid, clavotrapezius and splenius motoneurons. At lower cervical levels labeled fibers are distributed to the medial part of the ventral horn. Projections from the caudal Field H of Forel to thoracic or more caudal spinal levels are sparse. 3. Neurons in the INC-RF, together with a few neurons in the area of the nucleus of the posterior commissure, project bilaterally to the medial part of the upper cervical ventral horn, via the dorsal part of the ventral funiculus. This area includes motoneurons innervating prevertebral flexor muscles and some of the motoneurons of the biventer cervicis and complexus muscles. Further caudally, labeled fibers are distributed to the medial part of the ventral horn (laminae VIII and adjoining VII) similar to the projections of Field H of Forel. A few INC-RF projections were observed to low thoracic and lumbosacral levels. It is argued that the neurons in the caudal Field H of Forel, which project to the spinal cord are especially involved in the control of those fast vertical head movements which occur in conjunction with saccadic eye movements. In contrast the INC-RF projections to the spinal cord are responsible for slower, smaller movements controlling the position of the head in the vertical plane.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00247933
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  • 26
    Electronic Resource
    Electronic Resource
    Axis of preferred motion is a function of bar length in visual cortical receptive fields (1989)
    Springer
    Experimental brain research 76 (1989), S. 307-314 
    Details
    ISSN: 1432-1106
    Keywords: Moving stimuli ; Orientation specificity ; Preferred axes ; Spot-response-axis ; Striate cortex ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The responses of 82 simple cells and 41 complex cells in area 17 of anesthetized and paralysed cats were examined with light bars of different length. For 84% of the simple cells and 66% of the complex cells the preferred axis of orientation of a stationary flashing long bar (orientational selectivity) and the preferred axis of movement of a small spot were parallel. As a consequence, the axis of maximal response to a moving light spot was mostly orthogonal to the optimal axis of a moving bar. Thus, a single cell responds to two perpendicular axes of preferred movement one for a long bar and one for a light spot, respectively. For both axes independent direction preferences could be distinguished. Additional preferred axes of movement between the two orthogonal extremes could be found with moving bars of intermediate lengths. This can be explained by the fact that cells with a pronounced response to a moving spot showed a strong tendency for intermediate bar length to elicit responses consisting of a superposition of both components. Therefore, decreasing bar length resulted in a gradual rotation of the preferred direction of movement from orthogonal to parallel with respect to the orientational axis, rather than to a mere widening of the tuning curve. Accordingly, the change in orientation selectivity with decreasing bar length is a regular transition from the orientation dependent response to a response type that depends only on the movement axis of the spot. Thus, in a simple model, the resulting response characteristic can be interpreted as an average of both components weighted according to the length of the stimulus.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00247890
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  • 27
    Electronic Resource
    Electronic Resource
    Cat red nucleus activity preceding movement depends on initiation conditions (1989)
    Springer
    Experimental brain research 77 (1989), S. 271-282 
    Details
    ISSN: 1432-1106
    Keywords: Red nucleus ; Motor initiation ; Single-unit activity ; Reaction time ; Delayed movement ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The activity of 98 Red Nucleus neurons was recorded in 3 cats operantly conditioned to perform a ballistic forelimb flexion movement triggered after a brief sound in a simple Reaction Time condition, or Delayed after the same sound in the presence of a tone cue. Fifty-eight task related neurons presented changes of activity in either one or both conditions. Forty-four of them were studied quantitatively and classified in 3 categories: 1) only 16% of the units presented similar changes of firing preceding the triggered or delayed movement; 2) most units (55%) presented different changes of activity in the two conditions: in the Delayed condition, the activation occurred earlier before the movement, and/or the change in magnitude was reduced or the pattern of activity was modified; 3) moreover, for 29% of the units, the change of activity observed before movement in the Reaction Time condition was severely reduced or even absent in the Delayed condition. For some of these neurons a building-up of activity was observed very early in the Reaction Time condition, during the preparatory period, well before the occurrence of the conditioned stimulus. These results show that the Red Nucleus activity preceding a movement is clearly dependent on its initiation conditions. The distinct patterns of unit firing observed in the Reaction Time condition and in the Delayed condition are tentatively related to the different preparation and initiation constraints determined by the behavioral conditions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00274984
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  • 28
    Electronic Resource
    Electronic Resource
    Actions of excitatory amino acid antagonists on synaptic potentials of layer II/III neurons of the cat's visual cortex (1989)
    Springer
    Experimental brain research 78 (1989), S. 489-500 
    Details
    ISSN: 1432-1106
    Keywords: NMDA receptor ; Visual cortex ; Excitatory amino acid ; Slice ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Actions of excitatory amino acid (EAA) antagonists on the responses of cells in layers II/III and IV of the cat's visual cortex to stimulation of layer VI and the underlying white matter were studied in slice preparations. Antagonists used were 2-amino-5-phosphonovalerate (APV), a selective antagonist for the N-methyl-D-aspartate (NMDA) type of EAA receptors, and kynurenate, a broadspectrum antagonist for the three types of EAA receptors. In extracellular recordings it was demonstrated that most of the layer II/III cells were sensitive to APV, while the great majority of the layer IV cells were not, By contrast, kynurenate suppressed the responses completely in both layers. Excitatory post-synaptic potentials (EPSPs) evoked by stimulation of layer VI and the while matter were recorded intracellularly from layer II/III neurons. To determine whether the EPSPs were elicited mono- or polysynaptically, the synaptic delay for each EPSP was calculated from a pair of onset latencies of EPSPs evoked by stimulation of the two sites. Forty-two percent of the layer II/III cells were classified as having monosynaptic EPSPs. In 60% of these monosynaptic cells, the rising slope of the EPSPs was reduced by APV while in the other 40%, it was not. In the former (APV-sensitive cells), subtraction of the APV-sensitive component from the total EPSP indicated that the onset latency of the NMDA receptor-mediated component was roughly equal to that of the non-NMDA component. In the latter (APV-resistant cells), only the slowly-decaying component was in part mediated by NMDA receptors. The conduction velocities of the afferent fibers innervating APV-resistant cells were slower than those of the APV-sensitive cells, suggesting that both types of cells are innervated by different types of afferents. The polysynaptic EPSPs of almost all layer II/III cells were sensitive to APV. The subtraction method indicated that the NMDA component had about the same magnitude as the non-NMDA components. When the slices were superfused by a Mg2+-free solution, the EPSPs were potentiated dramatically, but this potentiation was reduced to the control level during the administration of APV. Similarly, APV-sensitive components were potentiated during the administration of bicuculline, a selective antagonist for gamma-aminobutyric acid receptors of A type. These results suggest that NMDA receptors participate, at varying degrees, in excitatory synaptic transmission at most layer II/III cells in the cat's visual cortex, and their actions appear to be regulated by intracortical inhibition.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00230237
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  • 29
    Electronic Resource
    Electronic Resource
    Effects of dark rearing on the development of visual callosal connections (1989)
    Springer
    Experimental brain research 78 (1989), S. 203-213 
    Details
    ISSN: 1432-1106
    Keywords: Corpus callosum ; Development ; Vision ; Dark rearing ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary It is now well established that during normal postnatal development there is a partial elimination of the callosal projections of cortical areas 17 and 18 in the cat and that visual experience early in life can modulate this process. In the present experiments, we quantitatively studied the influence of light, per se, by rearing cats in total darkness. Dark rearing exaggerates the normally occurring partial elimination of immature callosal projections: it causes a significant reduction in the total number of neurons in both the supra-and infragranular layers that send an axon through the corpus callosum and slightly narrows the distribution of these neurons across areas 17 and 18. These data demonstrate that visual stimulation is not necessary either to initiate the partial elimination of immature callosal projections or to stabilize a large fraction of the callosal projections present at birth. However, normal visual stimulation is necessary for the stabilization of the normal complement of callosal projections.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00230700
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  • 30
    Electronic Resource
    Electronic Resource
    Role of the sensorimotor cortex in postural adjustments accompanying a conditioned paw lift in the standing cat (1989)
    Springer
    Experimental brain research 78 (1989), S. 588-596 
    Details
    ISSN: 1432-1106
    Keywords: Motor cortex ; Conditioned movement ; Posture ; Balance control ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The role of the sensorimotor cortex in the postural adjustments associated with conditioned paw lifting movements was investigated in the cat. Cats were trained to stand quietly on four strain gauge equipped platforms and to perform a lift-off movement with one forelimb when a conditioned tone was presented. The parameters recorded were the vertical forces exerted by the paws on each platform, the lateral and antero-posterior displacements of rods implanted on the T2, T12, L5 vertebrae as well as their rotation, and the EMG of triceps and biceps of both forelimbs. Before lesion, the postural adjustment consisted of a “nondiagonal” pattern where the CG was displaced laterally inside the triangle formed by the three remaining supporting limbs. Here a lateral bending of the thoracic column toward the supporting forelimb could be observed. The associated EMG pattern consisted of an early activation of the triceps lateral head in the moving limb which was probably responsible for the body displacement toward the opposite side, and a late biceps activation associated with the lift. In the supporting forelimb, a coactivation of the biceps and triceps was usually present. After contralateral sensorimotor lesion, the conditioned lifting movements were lost for 4–15 days after the lesion, before being subsequently recovered. The same lateral CG displacement and bending of the back was seen after lesion as before, which indicates that the goal of postural adjustment was preserved. However, the means of reaching it were modified. In most of the intact animals, the CG displacement was achieved in one step, whereas in the animals with lesions, the displacement was made either according to a slow ramp mode or in a discontinuous manner involving several steps. The mechanisms responsible for this disturbance are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00230246
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  • 31
    Electronic Resource
    Electronic Resource
    Cytochemical studies of normal feline blood and bone marrow cells (1989)
    Springer
    Annals of hematology 58 (1989), S. 195-199 
    Details
    ISSN: 1432-0584
    Keywords: Cytochemistry ; Blood ; Bone marrow ; Leukocytes ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Blood and bone marrow cells of ten clinically healthy cats were stained for alkaline phosphatase (ALP), peroxidase (PO), chloroacetate esterase (CAE), alpha-naphthyl butyrate esterase (NBE), sudanophilia, and periodic acid-Schiff (PAS) reaction. Mature neutrophils in blood and bone marrow were devoid of ALP and NBE, but exhibited modest to strong PO, CAE, sudanophilia, and PAS reaction. In bone marrow, sudanophilia, PO, and CAE were prominent at the promyelocyte stage and diminished with cellular differentiation and maturation, while PAS reactivity increased with cell maturation usually from the myelocyte stage onwards. Myeloblasts were negative for all cytochemical reactions, but some large unidentifiable cells reacted strongly for ALP. Eosinophils were slightly reactive for ALP, CAE, and PAS, but not for PO, sudanophilia, and NBE. Basophil granules stained strongly for CAE, revealed PAS positivity, and stained negatively for PO, NBE, ALP, and sudanophilia. Slight ALP activity was detected in the intergranular cytoplasm of basophils. Lymphocytes and monocytes, with few exceptions, stained negatively. An occasional lymphocyte revealed slight globular NBE activity (NaF-resistant) and diffuse PAS reaction, while an occasional monocyte contained a few PO-positive and sudanophilic granules. Monocytes reacted modestly, whereas bone marrow macrophages reacted strongly for NBE (NaF-sensitive). Cells of the erythroid series stained negatively for all cytochemical reactions, megakaryocytes were PAS-positive, and platelets gave positive reactions for PAS and CAE.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00320772
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  • 32
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    Electronic Resource
    Feline sporotrichosis: A case report (1989)
    Springer
    Mycopathologia 108 (1989), S. 149-154 
    Details
    ISSN: 1573-0832
    Keywords: Sporotrichosis ; Sporothrix schenckii ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The isolation of Sporothrix schenckii from a female European cat it is described. The cat showed lengthened alopecic areas, with prominent nodules in the external surface of the thighs and abdomen. A mycological and histopathological studies of the lesions were carried out. The lesions resolved under treatment with 20% potassium iodide in doses of 0'1 ml/kg oral route in a 8 weeks period.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00436219
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  • 33
    Electronic Resource
    Electronic Resource
    Masthead (1989)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 12 (1989) 
    Details
    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
    URL: http://dx.doi.org/10.1002/cm.970120201
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  • 34
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    Electronic Resource
    Actomyosin organization during cytokinesis: Reversible translocation and differential redistribution in Dictyostelium (1989)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 12 (1989), S. 78-89 
    Details
    ISSN: 0886-1544
    Keywords: mitosis ; actin and myosin ; agar-overlay method ; immunofluorescence ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Synchronized cultures of Dictyostelium discoideum were used to study organizational changes of the cytoskeleton during mitotic cell division. The agar-overlay technique (Yumura et al.: J. Cell Biol. 99:894-899, 1984) was employed for immunofluorescence localization and video microscopic observation of living mitotic cells. The mitotic phase was defined by changes in chromosome configuration by using a double stain with the fluorescent dye DAPI.This study showed that the actin- and myosin-containing cytoskeleton was reversibly redistributed between the cortical ectoplasm and the endoplasm during prophase and telophase. Both actin and myosin filaments were dissociated from the cell cortex in prophase. Most of the actin and myosin was filamentous and remained in the endoplasm until telophase. Saltatory movements of organelles stopped suddenly, coincident with the breakdown of the cytoplasmic microtubule network. This change in the microtubule system was temporally coupled with the disappearance of actomyosin from the cortex. At the same time, the local vibrating movement of particles almost stopped, suggesting that the viscoelastic nature of the endoplasm was altered. In the late anaphase, actin and myosin relocalized to the cortical ectoplasm. Early in this phase, myosin filaments were localized specifically at the anticipated cleavage furrow region of the cleavage furrow, whereas actin filaments were redistributed more uniformly in the cell cortex, with an extremely large accumulation in the polar pseudopods. Subsequently the actin formed an orderly parallel array of cables along with myosin filaments in the contractile ring.The spatial segregation of actin and myosin in late anaphase was clearly demonstrated by multipolar cell division of artificially induced giant cells. Actin was relocalized in both the polar and the proximal constricting regions whereas myosin was only localized in the center of each pair of daughter microtubule networks where the cleavage furrow was formed. This study demonstrates that actin and myosin are reorganized by a temporally coordinated but spatially different mechanism during cytokinesis of Dictyostelium.
    Additional Material: 7 Ill.
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    225-Kilodalton phosphoprotein associated with mitotic centrosomes in sea urchin eggs (1989)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 12 (1989), S. 90-103 
    Details
    ISSN: 0886-1544
    Keywords: mitosis ; spindles ; microtubule-organizing centers ; antiphosphoprotein antibodies ; phosphorylation ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Protein phosphorylation during development of sea urchin eggs from fertilization to first cleavage was examined by labeling cells with specific antiphosphoprotein antibodies. Indirect immunofluorescence staining with monoclonal antithiophos-phoprotein antibody (Gerhart et al.: Cytobios 43:335-347, 1985) has revealed that nuclei as well as centrosomes, kinetochores, and midbodies were specifically thiophosphorylated in developing eggs incubated with adenosine 5′-O (3-thiotriphosphate) (ATP-γ-S). The phosphorylation reaction required Mg2+ but was not dependent on cAMP or calmodulin in detergent-extracted models. Centrosomes were purified by fractionation of isolated mitotic spindles with 0.5 M KCl extraction. The thiophosphoproteins were retained in the purified centrosomes and the antibody recognized a major 225-Kd polypeptide on immunoblots. In an independent preparation, a monoclonal antiphosphoprotein antibody (CHO3) was found also to react with mitotic poles and stained a 225-Kd polypeptide, confirming the centrosome specificity of this protein. Immunoelectron microscopy showed that the 225-Kd thiophosphoprotein was found at mitotic poles associated with granules to which mitotic microtubules were directly attached. Unlike centrosomes in permeabilized eggs, those in isolated spindles could not be thiophosphorylated, possibly due to inactivation or loss of either phosphorylation enzymes or cofactors, or both, during isolation. The immunofluorescence labeling of thiophosphate could be inhibited by ATP and AMP-PNP in a concentration-dependent manner. Exogenous ATP could abolish thiophosphate-staining more effectively when added with phosphatase inhibitors, suggesting a dynamic state in which centrosomal proteins are being phosphorylated and dephosphorylated in rapid succession by the action of protein kinase(s) and phosphatase(s).
    Additional Material: 9 Ill.
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    Rapid kinetochore movements in Mesostoma ehrenbergii spermatocytes: Action of antagonistic chromosome fibres (1989)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 13 (1989), S. 212-220 
    Details
    ISSN: 0886-1544
    Keywords: meiosis ; live observation ; oscillatory movements ; microtubule assembly-disassembly ; spindle forces ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Chromosome movements in Mesostoma ehrenbergii spermatocytes were studied using conventional video light microscopy. Kinetochore regions of the three bipolarly oriented bivalents displayed periodic back and forth movements directed to both poles at metaphase I, leading to periodic lenght changes of the bivalents. Velocity was 8-10 μm/min (maximum 17 μ/min), about one order of magnitude higher than the normal meiotic or mitotic chromosome movements of other species. One cycle of movement lasted for about 100 seconds. The movement of kinetochore regions implies that the antagonistic chromosome fibres periodically grow (assemble) and shorten (disassemble) at comparable rates. Poleward movements must be caused by forces generated in disassembling fibres, whereas movements away from the poles, accompanied by fibre growth, are probably brought about by the internal elastic force of the chromosomes. Antagonistic fibres of a bivalent can operate in or out of phase. The movements of the three kinetochore regions are coordinated insofar as growing and shortening fibres coexist in a half-spindle at almost any time [Fuge, H. (1987): European Journal of Cell Biology 44:294-298]. These observations are discussed in terms of microtubule dynamics.
    Additional Material: 7 Ill.
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    URL: http://dx.doi.org/10.1002/cm.970130308
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    2-Chloro adenosine triphosphate as substrate for sea urchin axonemal movement (1989)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 13 (1989), S. 239-244 
    Details
    ISSN: 0886-1544
    Keywords: sperm ; nucleotide analog ; kinetics ; Stronglyocentrotus purpuratus ; reactivation ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The 2-substituted ATP analog 2-Chloro ATP was tested for its capacity to support axonemal movement. The movement of sea urchin axonemes reactivated with 2-CI ATP appeared very similar to that with ATP. Detailed waveform analysis indicated that bend angle and shear amplitude were not significantly different for ATP and 2-CI ATP. Although wavelength differs at particular nucleotide concentrations, if normalized to the beat frequency, it is similar for ATP and 2-CI ATP. The main difference in the movement with the two analogs was seen in beat frequency and sliding velocity. The Vmax for beat frequency and mean sliding velocity was lower for 2-CI ATP. The apparent Km for beat frequency and sliding velocity was much lower for 2-CI ATP. The ratio of these two effects, that is, (Vmax/Km) is higher for 2-CI ATP. Thus 2-CI ATP is a good substrate for axonemal movement. The significantly lower Km of 2-CI ATP was also demonstrated by its ability to support oscillatory motion at concentrations below that for ATP. The observations identify the structures and conformation of substrate necessary to support axonemal movement.
    Additional Material: 6 Ill.
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    URL: http://dx.doi.org/10.1002/cm.970130403
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    A model for slow axonal transport and its application to neurofilamentous neuropathies (1989)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 12 (1989), S. 53-65 
    Details
    ISSN: 0886-1544
    Keywords: reversible binding ; computer simulation ; transport rates ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A model for slow axonal transport is developed in which the essential features are reversible binding of cytoskeletal elements and of soluble cytosolic proteins to each other and to motile elements such as actin microfilaments. Computer simulation of the equations of the model demonstrate that the model can account for many of the features of the SCa and SCb waves observed in pulse experiments. The model also provides a unified explanation for the increase and decrease of neurofilament transport rates observed in various toxicant-induced neuropathies.
    Additional Material: 7 Ill.
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    URL: http://dx.doi.org/10.1002/cm.970120107
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    Calmodulin is associated with microtubules forming in PTK1 cells upon release from nocodazole treatment (1989)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 12 (1989), S. 113-122 
    Details
    ISSN: 0886-1544
    Keywords: mitosis ; spindle ; kinetochore ; centrosome ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: To investigate the association of calmodulin (CaM) with microtubules (MTs) in the mitotic apparatus (MA), the distributions of CaM and tubulin were examined in cells in which the normal spindle organization had been altered. A fluorescent CaM conjugate with tetramethylrhodamine isothiocyanate (CaM-TRITC) and a dichlorotriazinyl aminofluorescein conjugate with tubulin (tubulin-DTAF) were injected into cells that had been treated with the MT inhibitor nocodazole. With moderate nocodazole concentration (0.3 μg/ml, 37°C, 4 h) in live cells, CaM-TRITC and tubulin-DTAF concentrated identically on or near the centrosomes and kinetochores. In serial sections of these cells, small MT segments were observed by transmission electron microscopy (TEM) in the regions where fluorescent protein had concentrated. When a higher drug concentration was used (3.0 μg/ml, 37°C, 4 h), no regions of CaM-TRITC or tubulin-DTAF localization were observed, and no MTs were observed when serial sections were examined by TEM. However, following release from the high-concentration nocodazole block, CaM-TRITC colocalized with newly formed MTs at the kinetochores and centrosomes. Later in the recovery period, when chromosome-to-pole fibers had formed, CaM association with kinetochores diminished, ultimately attaining its normal pole-proximal association with kinetochore MTs in cells that progressed through mitosis. We interpret these observations as supporting the hypothesis that in the MA, CaM attains a physical association with kinetochore MTs and suggest that CaM-associated MTs may be inherently more stable.
    Additional Material: 7 Ill.
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    URL: http://dx.doi.org/10.1002/cm.970120206
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    Cellular morphogenesis and the formation of marginal bands in amphibian splenic erythroblasts (1989)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 12 (1989), S. 157-168 
    Details
    ISSN: 0886-1544
    Keywords: axolotl ; cell differentiation ; cell shape ; cytoskeleton ; nucleated erythrocyte ; microtubule ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The spleen of Ambystoma mexicanum (axolotl) larvae develops as a closed sac containing differentiating nucleated erythrocytes, and is typically isolated from the general circulation for about 10 days post-hatching. Beginning 3-4 days posthatching, it can be removed intact for examination of the morphology and cytoskeletal structure of the erythropoietic cells. In the smallest (earliest) spleens, spheroidal cells predominate, while older ones contain a preponderance of cells exhibiting the flattened elliptical morphology typical of all non-mammalian vertebrate erythrocytes. Most striking in the splenic erythroid population are cells with singly or doubly pointed morphology. Though common in the developing spleen and circulation of young larvae, pointed cells are less frequently encountered in the circulation of older larvae, indicating that they are intermediate stages in the differentiation of spheroids to flattened ellipsoids. This is supported by structural observations on cytoskeletons prepared from the splenic cells. Incomplete singly and doubly pointed marginal bands of microtubules are observed, many of which contain a pair of centrioles within or close to a pointed end, suggestive of organizing center function. The observations are consistent with a sequence of changes in cell morphology from spherical to doubly pointed to singly pointed to flattened ellipse, causally linked to stages of marginal band biogenesis.
    Additional Material: 9 Ill.
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    URL: http://dx.doi.org/10.1002/cm.970120305
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    Myofibril assembly is linked with vinculin, α-actinin, and cell-substrate contacts in embryonic cardiac myocytes in vitro (1989)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 12 (1989), S. 185-194 
    Details
    ISSN: 0886-1544
    Keywords: myofibril assembly ; focal contacts ; vinculin ; α-actinin ; connectin ; immunocytochemistry ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The relationship of nascent myofibrils with the accumulation of adhesion plaque proteins and the formation of focal cell contacts was studied in embryonic chick cardiac myocytes in vitro. The cultures were double-stained with various combinations of the specific antiactin drug phalloidin and antibodies against vinculin, α-actinin, connectin (titin), myosin heavy chain, fibronectin, and desmin and examined under fluorescence and interference reflection microscopy.In the areas of myofibril assembly, vinculin and α-actinin plaques were formed at the ventral sarcolemmae. These areas overlapped with the sites of cell-to-substrate focal contacts and extracellular fibronectin. Because the myofibrils always ran in a straight line between these sites, polarized lines appeared to be generated within the cells in response to their physical (e.g., stress) and/or biochemical environment (e.g., adhesion plaque proteins). The possible presence of other factors cannot be ruled out for the proper alignment of myofibrils. As soon as myofibrils came to span between these adhesion sites, they exhibited typically mature cross-striated characteristics. Thus, the formation of these inferred lines has some relation to or is in fact necessary for the maturation of myofibrils, in addition to the directional arrangement of sarcomeric proteins.Additionally, synthesis and distribution of myosin and connectin were tightly linked during early developmental (premyofibril and myofibril) stages. The spatial deployment of desmin was not coupled with vinculin. Thus, connectin and desmin do not appear to form the initial scaffold of sarcomeres.
    Additional Material: 11 Ill.
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    Erratum (1989)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 12 (1989), S. 283-283 
    Details
    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
    URL: http://dx.doi.org/10.1002/cm.970120409
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    Differential localisation of tyrosinated, detyrosinated, and acetylated α-tubulins in neurites and growth cones of dorsal root ganglion neurons (1989)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 12 (1989), S. 273-282 
    Details
    ISSN: 0886-1544
    Keywords: cytoskeleton ; microtubules ; axons ; sensory neurons ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The comparative distribution of tyrosinated, detyrosinated, and acetylated α-tubulins was examined in neurites of rat dorsal root ganglion neurones in culture using immunofluorescence microscopy. Phase contrast observations of single neurones revealed that the neurites were actively motile, and rhodamine phalloidin staining of actin filaments showed the extent of lamellopodia and microspike projections from the growth cones. From double-labelling experiments using antibodies against tyrosinated, detryrosinated, or acetylated α-tubulin, it was found that the three different isoforms were differentially localised in neurites and growth cones. Detyrosinated and acetylated forms of α-tubulin were in the main restricted to the neurites extending no further than the base of the growth cones. Tyrosinated α-tubulin was, however, distributed throughout the body of the growth cone and into the base of some microspikes. Following treatment with taxol to promote microtubule assembly, detyrosinated and acetylated α-tubulins were found to be colocalised with tyrosinated α-tubulins throughout the growth cones of all cells examined. These results would be consistent with axonal transport of tyrosinated α-tubulin followed by assembly in the growth cone and subsequent detyrosination and acetylation. In addition the presence of unmodified α-tubulin in the growth cone may be necessary for the provision of labile microtubules for growth cone motility and extension.
    Additional Material: 6 Ill.
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    URL: http://dx.doi.org/10.1002/cm.970120408
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    Chemoattractant-elicited translocation of myosin in motile Dictyostelium (1989)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 13 (1989), S. 158-169 
    Details
    ISSN: 0886-1544
    Keywords: chemotaxis ; cAMP ; cytoskeleton ; ameba ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The distribution of myosin was studied in amebae of the Ax-3 and NC-4 strains of Dictyostelium migrating at room temperature, using indirect immunofluorescence of aggregation-competent amebae and the agar-overlay technique. Amebae were fixed in methanol-formaldehyde or absolute acetone at -15°C before or after stimulation with micromolar cyclic AMP at room temperature (20-25°C). Myosin was detected by monoclonal antibodies to Dictyostelium myosin heavy chain followed by a fluorescent secondary antibody that had been preabsorbed to remove nonspecific staining. In both strains there was a striking increase in intensity of anti-myosin immunofluorescence in the cortex where it appeared as a continuous ring 30 seconds after addition of cyclic AMP. This correlated with a rounding up of the cell body. Sixty seconds after stimulation there was a clear reduction of cytoplasmic myosin rods in conjunction with the increased cortical localization. At this time extensions of largely hyaline cytoplasm were observed that extended beyond the cortical shell of myosin. Two minutes after the stimulus the immunofluorescence remained as a distinct line at the cortex, but the cells began to resume in elongated shape. By 3 minutes (NC-4 strain) or 5 minutes (Ax-3 strain) the amebae had largely returned to the control shape, and myosin had returned to its control distribution. Counts of the treated cells at different time points substantiated the observations of individual cells. The time course of translocation of myosin in the Ax-3 strain parallels the time course of myosin phosphorylation reported in previous studies. The results are interpreted in terms of a working hypothesis for the mechanism of translocation.
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    URL: http://dx.doi.org/10.1002/cm.970130304
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    Immunolocalization of pericentriolar material in algal mitotic spindles (1989)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 13 (1989), S. 225-238 
    Details
    ISSN: 0886-1544
    Keywords: centrosome ; DAPI ; immunofluorescence ; immunoperoxidase ; microtubules ; mitosis ; scleroderma serum ; tubulin ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Double-label immunofluorescence of tubulin and preicentriolar material (PCM) was carried out with mitotic nuclei in the coenocytic green alga Ernodesmis. Spindle poles are heavily labeled with serum 5051 (anti-PCM) from midprophase through mid- to late anaphase, and bright fluorescence is also evident at the tips of the elongated interzonal spindle in telophase nuclei. Very faint labeling with anti-PCM is also detected throughout the spindle (and/or its matrix) at all mitotic stages. Control treatments demonstrated that nonspecific surface labeling of chloroplasts with anti-PCM may be due to some naturally occurring component of human sera rather than to specific labeling by the anti-PCM serum. Ultrastructural work indicates that the centrosome is always associated with spindle poles through anaphase, but not with the tips of the interzonal telophase Immunoper-oxidase electron microscopy verifies that anti-PCM labels the centrosomes of mitotic nuclei in these cells. However, labeling is also present inside the presistent nuclear envelope at the spindle poles, during metaphase, anaphase, and at the tips of the interzonal spindles. Regions of heaviest labeling correspond with amorphous material near the centrioles and at the spindle poles, as evident in conventional electron microscope preparations. The origin of intranuclear amorphous material that labels with anti-PCM is unclear, but the ends of many spindle microtubules are embedded in it, especially at anaphase, and the tips of microtubules near the amorphous material are often labeled with the antiserum. These results indicate for the first time that serum 5051 does indeed label PCM at the poles of centric spindles in plant cells. Although the location of the labeled material suggests it is associated with the nucleation of spindle microtubules, this conclusion requires more information about microtubule dynamics in these cells. Caution is also warranted in interpreting variant anti-PCM labeling patterns in other plant cells because of spurious labeling of the spindle itself and other cytoplasmic organelles.
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    Biological roles of actin-binding proteins in Dictyostelium discoideum examined using genetic techniques (1989)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 14 (1989), S. 69-74 
    Details
    ISSN: 0886-1544
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Additional Material: 5 Ill.
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    URL: http://dx.doi.org/10.1002/cm.970140114
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    Application of antisense RNA to the study of the cytoskeleton: Background, principles, and a summary of results obtained with myosin heavy chain (1989)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 14 (1989), S. 92-102 
    Details
    ISSN: 0886-1544
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970140118
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    Human molecular genetics and the elucidation of the primary biochemical defect in duchenne muscular dystrophy (1989)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 14 (1989), S. 163-168 
    Details
    ISSN: 0886-1544
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/cm.970140127
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    Masthead (1989)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 14 (1989) 
    Details
    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
    URL: http://dx.doi.org/10.1002/cm.970140201
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    Editorial (1989)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 14 (1989), S. 177-177 
    Details
    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
    URL: http://dx.doi.org/10.1002/cm.970140202
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    Membrane-bound myosin-l provides new mechanisms in cell motility (1989)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 14 (1989), S. 178-182 
    Details
    ISSN: 0886-1544
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/cm.970140203
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    Structure of the myosin head (1989)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 14 (1989), S. 183-186 
    Details
    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
    URL: http://dx.doi.org/10.1002/cm.970140204
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    Altering the vector of polarity of BHK syncytia changes their motile behavior (1989)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 14 (1989), S. 187-193 
    Details
    ISSN: 0886-1544
    Keywords: centrosphere ; locomotion ; MTOC ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: We have previously shown that BHK syncytia have the ability to locomote provided the centrospheres are clustered and located adjacent to the cluster of nuclei. This article reports that experimental reorganizations of the centrospheres or the nuclei change the motile behavior of BHK syncytia in a way that is consistent with our previous observations: When fusion of the multiple nuclei occurred in stationary syncytia whose multiple nuclei encircled the centrosphere cluster, the centrospheres were expelled from the ring of nuclei. Consequently, locomotion was initiated in these syncytia even if they had been previously stationary for up to 5 days. Conversely, when a 2-hour incubation in 5 μg/ml cytocholasin B caused the cluster of nuclei to surround the centrosphere cluster, the locomotion of the syncytia was inhibited. Similarly, the dispersal of the centrosphere cluster induced by a 4-hour incubation in 1 μg/ml of colcemid resulted in the long-term cessation of locomotion in motile syncytia.
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    URL: http://dx.doi.org/10.1002/cm.970140205
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  • 54
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    Analysis of cell division using fluorescently labeled actin and myosin in living PtK2 cells (1989)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 14 (1989), S. 201-219 
    Details
    ISSN: 0886-1544
    Keywords: cytokinesis ; microinjection ; cleavage furrow ; mitosis ; midbody ; stress fibers ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Actin and the light chains of myosin were labeled with fluorescent dyes and injected into interphase PtK2 cells in order to study the changes in distribution of actin and myosin that occurred when the injected cells subsequently entered mitosis and divided. The first changes occurred when stress fibers in prophase cells began to disassemble. During this process, which began in the center of the cell, individual fibers shortened, and in a few fibers, adjacent bands of fluorescent myosin could be seen to move closer together. In most cells, stress fiber disassembly was complete by metaphase, resulting in a diffuse distribution of the fluorescent proteins throughout the cytoplasm with the greatest concentration present in the mitotic spindle. The first evidence of actin and myosin concentration in a cleavage ring occurred at late anaphase, just before furrowing could be detected. Initially, the intensity of fluorescence and the width of the fluorescent ring increased as the ring constricted. In cells with asymmetrically positioned mitotic spindles, both protein concentration and furrowing were first evident in the cortical regions closest to the equator of the mitotic spindle. As cytokinesis progressed in such asymmetrically dividing cells, fluorescent actin and myosin appeared at the opposite side of the cell just before furrowing activity could be seen there. At the end of cytokinesis, myosin and actin were concentrated beneath the membrane of the midbody and subsequently became organized in two rings at either end of the midbody.
    Additional Material: 12 Ill.
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    URL: http://dx.doi.org/10.1002/cm.970140207
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    Distribution of phosphorylated spindle-associated proteins in the diatom Stephanopyxis turris (1989)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 12 (1989), S. 33-41 
    Details
    ISSN: 0886-1544
    Keywords: phosphorylation ; MPM-2 ; mitotic spindle ; microtubule-associated protein ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Mitotic spindles isolated from the diatom Stephanopyxis turris become thiophosphorylated in the presence of ATPγS at specific locations within the mitotic apparatus, resulting in a stimulation of ATP-dependent spindle elongation in vitro. Here, using indirect immunofluorescence, we compare the staining pattern of an antibody against thiophosphorylated proteins to that of MPM-2, an antibody against mitosis-specific phosphoproteins, in isolated spindles. Both antibodies label spindle poles, kinetochores, and the midzone. Neither antibody exhibits reduced labeling in salt-extracted spindles, although prior salt extraction inhibits thiophosphorylation in ATPγS. Furthermore, both antibodies recognize a 205 kd band on immunoblots of spindle extracts. Microtubule-organizing centers and mitotic spindles label brightly with the MPM-2 antibody in intact cells. These results show that functional mitotic spindles isolated from S. turris are phosphorylated both in vivo and in vitro. We discuss the possible role of phosphorylated cytoskeletal proteins in the control of mitotic spindle function.
    Additional Material: 5 Ill.
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    URL: http://dx.doi.org/10.1002/cm.970120105
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    Announcements (1989)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 12 (1989), S. 66-66 
    Details
    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
    URL: http://dx.doi.org/10.1002/cm.970120108
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    Binding of kinesin to stress fibers in fibroblasts under condition of microtubule depolymerization (1989)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 12 (1989), S. 71-77 
    Details
    ISSN: 0886-1544
    Keywords: microtubule ; colchicine ; cold-treatment ; kinesin localization ; EBTr cells ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The localization of kinesin in EBTr (bovine embryonic trachea fibroblast) cells was studied by indirect immunofluorescence microscopy using an affinity-purified antibody against bovine adrenal kinesin.It has already been shown that in interphase cells a part of kinesin is located on microtubules and the rest diffusely distributed throughout the cytoplasm [Murofushi et al., 1988]. When microtubules were depolymerized with cold or colchicine treatment, antikinesin antibody-stained fibrous components distinct from microtubules. These fibrous structures were considered to be stress fibers because they were stained with rhodamine-phalloidin and because the fibrous staining with antikinesin antibody was completely lost by treating the cells with cytochalasin D along with colchicine. When cold-treated cells in which a major part of kinesin had been localized on stress fibers were incubated at 37°C, kinesin reappeared on reconstituted microtubules. These observations strongly suggest that kinesin has affinity not only to microtubules but also to stress fibers in culture cells.
    Additional Material: 6 Ill.
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    URL: http://dx.doi.org/10.1002/cm.970120202
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    Announcement (1989)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 12 (1989), S. 123-123 
    Details
    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
    URL: http://dx.doi.org/10.1002/cm.970120207
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    Immunocytochemical studies of spectrin in hamster cardiac tissue (1989)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 12 (1989), S. 139-149 
    Details
    ISSN: 0886-1544
    Keywords: spectrin ; hamster ; cardiac tissue ; cytoskeletal-membrane ; myofibrils ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The spectrins are a family of cytoskeletal-membrane proteins that have a wide tissue distribution. In the present study, we employed polyclonal antibodies made against mammalian and avian erythroid spectrins as well as mammalian brain spectrin to assess their presence and distributions in the mammalian heart. Western blot analyses revealed that all three antibodies were specific for a 240,000 molecular weight α-spectrin subunit found in hamster erythrocyte ghost homogenates, whole hamster heart, and isolated hamster cardiac myofibril homogenates. Spectrin staining was absent from the Triton X-100-extracted supernatant fraction of myofibril preparations, suggesting that the protein is linked to the myofibril precipitate after exposure to the detergent. Frozen, unfixed, 2-μm-thick; sections of adult, Syrian golden hamster cardiac tissue exhibited strong immunofluorescent staining of intercalated discs and Z-bands using all three antibodies. In addition, the mammalian erythroid spectrin antibodies showed staining of the sarcolemma, and in cross section, revealed a delicate internal network of staining that appears to surround individual myofibrils. This may be T-tubule-associated staining. Myofibrils isolated from cardiac myocytes using Triton X-100 show positive Z-band staining using all three antibodies. Double staining with Texas Red-labeled monoclonal desmin and FITC-labeled polyclonal spectrin antibodies revealed that both stained the myofibrillar Z-line regions. These results demonstrate that spectrin is closely associated with the membranes, myofibrils, and intermediate filaments in the mammalian heart.
    Additional Material: 6 Ill.
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    URL: http://dx.doi.org/10.1002/cm.970120303
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    Direct visualization of bipolar myosin filaments in stress fibers of cultured fibroblasts (1989)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 12 (1989), S. 150-156 
    Details
    ISSN: 0886-1544
    Keywords: stress fibers ; fibroblasts ; myosin ; bipolar filaments ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The authors examined the molecular organization of myosin in stress fibers (microfilament bundles) of cultured mouse embryo fibroblasts. To visualize the organization of myosin filaments in these cells, fibroblast cytoskeletons were treated with gelsolin-like protein from bovine brain (hereafter called brain gelsolin), which selectively disrupts actin filaments. As shown earlier [Verkhovsky et al., 1987], this treatment did not remove myosin from the stress fibers. The actin-free cytoskeletons then were lightly sonicated to loosen the packing of the remaining stress fiber components and fixed with glutaraldehyde.Electron microscopy of platinum replicas of these preparations revealed dumbbell-shaped structures of approximately 0.28 μm in length, which were identified as bipolar myosin filaments by using antibodies to fragments of myosin molecule (subfragment I and light meromyosin) and colloidal gold label. Bipolar filaments of myosin in actin-free cytoskeletons were often organized in chains and lattices formed by end-to-end contacts of individual filaments at their head-containing regions. Therefore, after extraction of actin, it was possible for the first time to display bipolar myosin filaments in the stress fibers of cultured cells.
    Additional Material: 4 Ill.
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    URL: http://dx.doi.org/10.1002/cm.970120304
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    Masthead (1989)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 12 (1989) 
    Details
    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
    URL: http://dx.doi.org/10.1002/cm.970120401
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    Copurification of kinesin polypeptides with microtubule-stimulated Mg-ATPase activity and kinetic analysis of enzymatic properties (1989)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 12 (1989), S. 195-215 
    Details
    ISSN: 0886-1544
    Keywords: mechanochemistry ; fast axonal transport ; cytoskeleton ; vesicle ; motor protein ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Determination of kinetic properties for kinesin adenosine triphosphatase (ATPase), a proposed motor for transport of membranous organelles, requires adequate amounts of kinesin with a consistent level of enzymatic activity. A purification procedure is detailed that produces approximately 2 mg of kinesin at up to 96% purity from 800 g of bovine brain. This protocol consists of a microtubule affinity step using 5′-adenylylimidodiphosphate (AMP-PNP); followed by gel filtration, ion exchange, and hydroxylapatite chromatography; and then sucrose density gradient centrifugation. The microtubule-activated ATPase activity of kinesin coeluted with kinesin polypeptides throughout the purification. Highly purified kinesin had a Vmax of 0.31 μmol/min/mg in the presence of microtubules, with a Km for ATP of 0.20 mM. The kinetic constants obtained in these studies compare favorably with physiological levels of ATP and microtubules. Variations in buffer conditions for the assay were found to affect ATPase activity significantly. A study of the ability of kinesin to utilize a variety of cation-ATP complexes indicated that kinesin is a microtubule-stimulated Mg-ATPase, but kinesin is able to hydrolyze Ca-ATP, Mn-ATP, and Co-ATP as well as Mg-ATP in the presence of microtubules. In the absence of microtubules, Ca-ATP appears to be the best substrate. Studies with several inhibitors of ATPases determined that vanadate inhibited kinesin ATPase at the lowest concentrations of inhibitor, but significant inhibition of the ATPase also occurred with submillimolar concentrations of AMP-PNP. Other inhibitors of kinesin include N-ethylmaleimide, adenosine diphosphate (ADP), pyrophosphate, and tripolyphosphate. Further characterization of the kinetic properties of the kinesin ATPase is important for understanding the molecular mechanisms for transport of membranous organelles along microtubules.
    Additional Material: 10 Ill.
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    URL: http://dx.doi.org/10.1002/cm.970120403
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    Changes in the association of actin-binding proteins with the actin cytoskeleton during chemotactic stimulation of Dictyostelium discoideum (1989)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 13 (1989), S. 57-63 
    Details
    ISSN: 0886-1544
    Keywords: ABP-120 ; myosin ; actin polymerization ; amoeboid chemotaxis ; cAMP ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Triton-insoluble cytoskeletons were isolated from Dictyostelium discoideum AX3 cells prior to and following stimulation with 2′deoxy cyclic adenosine monophos-phate (cAMP). Temporal changes in the content of actin and a 120,000 dalton actin-binding protein (ABP-120) in cytoskeletons following stimulation were monitored. Both actin and ABP-120 were incorporated into the cytoskeleton at 30-40 seconds following stimulation, which is cotemporal with the onset of pseudopod extension during stimulation of amoebae with chemoattraciants. Changes in the content of total cytoskeletal protein and cytoskeletal myosin were determined under the same experimental conditions as controls. These proteins exhibited different kinetics from those of cytoskeletal ABP-120 and actin following the addition of 2′deoxy cAMP. The authors concluded that the association of ABP-120 with the cytoskeleton is regulated during cAMP signalling. Furthermore, these results indicate that ABP-120 is involved in cross-linking newly assembled actin filaments into the cytoskeleton during chemoattractant-stimulated pseudopod extension.
    Additional Material: 6 Ill.
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    URL: http://dx.doi.org/10.1002/cm.970130107
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    Cytoskeletal features of the syncytial epidermis of the tapeworm Hymenolepis diminuta (1989)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 13 (1989), S. 41-56 
    Details
    ISSN: 0886-1544
    Keywords: cytoskeleton ; ultrastructure ; tegument ; syncytium ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A hallmark feature of parasitic platyhelminths is a cytoarchitecturally unusual syncytial epidermis composed of a peripheral layer of continuous cytoplasm (the ectocytoplasm) connected to underlying nucleated cell bodies by small cytoplasmic bridges. The helminth epidermis, or tegument, plays important roles in protection and nutrient acquisition; cestodes, in fact, completely lack a gastrointestinal tract and absorb all nutritive material through the tegument. Perhaps not surprisingly, the cestode tegument bears certain resemblances to the mucosal epithelium of the vertebrate small intestine, including the possession of a microvillous brush border upon the surface of the ectocytoplasm. In contrast to the intestinal epithelial cell, however, very little is known concerning the nature and organization of the cytoskeleton within the helminth epidermis. Therefore, a number of different microscopical preparative techniques were used to examine the tegument of the tapeworm Hymenolepis diminuta for the presence and distribution of microfilaments, intermediate filaments, and microtubules. It was found that both actin-containing microfilaments and intermediate-sized filaments are present but are restricted to specific locations along the plasmalemmae of the ectocytoplasm. In contrast, microtubules are found throughout the tegument, and are concentrated in the supranuclear regions of the perikarya and in the cytoplasmic bridges interconnecting the perikarya and ectocytoplasm. Unlike brush borders of most other epithelia, the cestode epidermal brush border lacks a filamentous terminal web and is instead associated with microtubules. A network of fine filaments, 5-8 nm in diameter but distinct from actin-containing microfilaments, runs throughout the ectocytoplasm and appears to interlink tegumental vesicles. These fine filaments may represent the primary “skeletal” system responsible for maintaining the structure of the tegumental cytoplasm.
    Additional Material: 33 Ill.
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    URL: http://dx.doi.org/10.1002/cm.970130106
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    Use of a novel Chlamydomonas mutant to demonstrate that flagellar glycoprotein movements are necessary for the expression of gliding motility (1989)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 13 (1989), S. 1-8 
    Details
    ISSN: 0886-1544
    Keywords: flagella ; membrane ; glycoproteins ; concanavalin A ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: As an alternative to swimming through liquid medium by the coordinated bending activity of its two flagella, Chlamydomonas can exhibit whole cell gliding motility through the interaction of its flagellar surfaces with a solid substrate. The force transduction occurring at the flagellar surface can be visualized as the saltatory movements of polystyrene microspheres. Collectively, gliding motility and polystyrene microsphere movements are referred to as flagellar surface motility. The principal concanavalin A binding, surface-exposed glycoproteins of the Chlamydomonas reinhardtii flagellar surface are a pair of glycoproteins migrating with apparent molecular weight of 350 kDa. It has been hypothesized that these glycoproteins move within the plane of the flagellar membrane during the expression of flagellar surface motility. A novel mutant cell line of Chlamydomonas (designated L-23) that exhibits increased binding of concanavalin A to the flagellar surface has been utilized in order to restrict the mobility of the concanavalin A-binding flagellar glycoproteins. Under all conditions where the lateral mobility of the flagellar concanavalin A binding glycoproteins is restricted, the cells are unable to express whole cell gliding motility or polystyrene microsphere movements. Conversely, whenever cells can redistribute their concanavalin A binding glycoproteins in the plane of the flagellar membrane, they express flagellar surface motility. Since the 350 kDa glycoproteins are the major surface-exposed flagellar proteins, it is likely that most of the signal being followed using fluorescein isothiocyanate (FITC)-concanavalin A is attributable to these high molecular weight glycoproteins. Therefore, it is likely that the 350 kDa glycoproteins are the ones that must move laterally in the plane of the flagellar membrane in order for the cell to express whole cell gliding motility and microsphere movements along the flagellar surface. This study represents one of the first demonstrations, in any cell type, that whole cell locomotion requires glycoprotein movement within the plane of the plasma membrane.
    Additional Material: 4 Ill.
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    URL: http://dx.doi.org/10.1002/cm.970130102
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    Immunocytochemical studies with antibodies to three proteins prominent in the isolated microtubule cytoskeleton of a trypanosomatid (1989)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 13 (1989), S. 145-157 
    Details
    ISSN: 0886-1544
    Keywords: microtubule ; membrane ; sytoskeleton ; Trypanosomatidae ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The cytoskeleton of Crithidia fasciculata consists of a corset of paralle microtubules enclosing the cell body and closely underlying the plasma membrane. Distinct sets of crosslinks appear to connect tubules to each other and to membrane. Our objective is to determine the composition of these crosslinks and to elucidate the basis of this spectacular example of membrane-microtubule interaction. We purified three proteins (designated COP-33, -41, and -61 by their subunit Mr), which were consistently abundant in highly purified cytoskeletons. All three bound strongly to microtubules in vitro, and the first two induced bundles through periodic crosslinking. Polyclonal antibodies against each have been used to try to localize these proteins in thin sections of cells or whole mounts of cytoskeletons. Antibodies to COP-41 bound sepcifically to glycosomes, organelles that encapsulate many glycolytic enzymes in these protozoa, and COP-41 has been identified as glyceraldehyde 3-P dehydrogenase.
    Additional Material: 7 Ill.
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    URL: http://dx.doi.org/10.1002/cm.970130303
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    Specialized cytoskeletal elements in mammalian eggs: Structural and biochemical evidence for their composition (1989)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 13 (1989), S. 104-111 
    Details
    ISSN: 0886-1544
    Keywords: embryo ; hamster ; detergent extraction ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Mammalian eggs and embryos contain an extensive detergent-resistant cytoskeletal network, including many elements which have been referred to as sheets in hamster eggs. In this study we examined the structure of the sheet-like components by using embedment-free sections and freeze-fracture electron microscopy and found that the sheets are composed of both filamentous and particulate components. In addition, exposure to a high salt extraction medium resulted in the disappearance of the sheets at the ultrastructural level. SDS-polyacrylamide gel electrophoresis of the cell fractions revealed four stainable proteins solubilized by the high salt extraction with one of the proteins being greatly enriched. Because these cytoskeletal sheets undergo an extensive reorganization coincident with key events during early development they serve as internal markers for the establishment of polarity and subsequent differentiation of the first embryonic epithelium, the trophectoderm.
    Additional Material: 7 Ill.
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    URL: http://dx.doi.org/10.1002/cm.970130205
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    Masthead (1989)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 13 (1989) 
    Details
    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
    URL: http://dx.doi.org/10.1002/cm.970130301
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    Myosin regulation and calcium transients in fibroblast shape change, attachment, and patching (1989)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 13 (1989), S. 112-122 
    Details
    ISSN: 0886-1544
    Keywords: cytoskeleton ; cell adhesion ; light chain phosphorylation ; immunofluorescence microscopy ; fluorescent indicators ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Following our study in Balb/c 3T3 cells and other cultured fibroblasts of the changes in myosin light chain phosphorylation associated with alterations in cell shape, attachment, and receptor patching, we have now determined the corresponding changes in cytoskeletal myosin distribution, and in the cellular calcium concentration, since this might, in part, mediate such responses.Immunofluorescence microscopy showed that myosin assembly into ordered forms such as actomyosin bundles and myosin sheath almost always correlated with previously shown high phosphorylation levels of myosin regulatory light chain, whereas diffuse distributions usually correlated with low or undetectable levels. An exception was observed in treatment to alter cellular cAMP levels when, in a biphasic response, assembly was correlated inversely with the phosphorylation states shown previously.Fluorescent indicators for intracellular calcium concentration, [Ca++]i, showed that myosin disassembly by trypsin or EGTA acting externally on the cells was preceded by a transient increase in [Ca++]i. For EGTA this was associated with transient recruitment of myosin into dorsal sheath structure as well as the transient enhancement of phosphorylation shown earlier. Blockage of EGTA-induced disassembly could be achieved by azide, which also caused an immediate increase in [Ca++]i and inhibited its subsequent decline. Trypsin-induced dephosphorylation did not appear to involve an eventual reduction of [Ca++]i. Therefore, in many but not all of the systems studied, correlated changes were observed in myosin assembly, [Ca++]i, and the myosin phosphorylation levels shown earlier.
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    URL: http://dx.doi.org/10.1002/cm.970130206
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    Developmental changes in the arrangement of cortical microtubules in stomatal cells of oat (Avena sativa L.) (1989)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 13 (1989), S. 170-180 
    Details
    ISSN: 0886-1544
    Keywords: Avena ; cytoskeleton ; Gramineae ; guard cell ; microtubule ; stomatal complex ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Changes in microtubule organization were monitored in the stomatal complexes of Avena sativa using tubulin immunocytochemistry. Radial arrays of cortical microtubules, previously thought to be characteristic of guard cells, also appear in adjacent subsidiary cells early in development. The subsidiary cell arrays are evident even before guard cells form via division of precursor guard mother cells. Thus, before the stomatal pore opens between sister guard cells, each complex contains four similar microtubule arrays. As the pore opens, however, the subsidiary cell system is reorganized into a network of microtubules distributed along the length of the cell. A similar change is effected in the guard cells after the pore opens. Subsidiary cells and guard cells elongate during later stages of differentiation, and a thickened wall is deposited int he narrow midzone of the latter. At the same time, microtubules in both cells assume a more axial orientation. The results are discussed in terms of developmental symmetry and the control of microtubule organization and cell wall deposition.
    Additional Material: 7 Ill.
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    URL: http://dx.doi.org/10.1002/cm.970130305
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    Bacterial expression of eukaryotic contractile proteins (1989)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 14 (1989), S. 3-11 
    Details
    ISSN: 0886-1544
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970140104
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    Correlated distribution of actin, myosin, and microtubules at the leading edge of migrating swiss 3T3 fibroblasts (1989)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 14 (1989), S. 527-543 
    Details
    ISSN: 0886-1544
    Keywords: immunofluorescence ; video-enhanced contrast microscopy ; protrusions ; lamellipodia ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The formation of lamellipodia in migrating cells involves dynamic processes that occur in a cyclic manner as the leading edge of a cell slowly advances. We used video-enhanced contrast microscopy (VEC) to monitor the motile behavior of cells to classify protrusions into the temporal stages of initial and established protrusions (Fisher et al.: Cell Motility and the Cytoskeleton 11:235-247, 1988), and to monitor the fixation of cells. Multiple parameter fluorescence imaging methods (DeBiasio et al.: Journal of Cell Biology 105:1613-1622, 1987; Waggoner et al.: Methods in Cell Biology, Vol. 30, Part B, pp. 449-478, 1989) were then used to determine and to map accurately the distributions of actin, myosin and microtubules in specific types of protrusions. Initial protrustions exhibited no substructure as evidenced by VEC and actin was diffusely arranged, while myosin and microtubules were absent. Newly established protrusions contained diffuse actin as well as actin in microspikes. There was a delay in the appearance of myosin into established protrusions relative to the presence of actin. Microtubules were found in established protrusions after myosin was detected, and they were oriented parallel to the direction of migration. Actin and myosin were also localized in fibers transverse to the direction of migration at the base of initial and established protrusions. Image analysis was used to quantify the orientation of actin fibers relative to the leading edge of motile cells. The combined use of VEC, multiple parameter immunofluorescence, and image analysis should have a major impact on defining complex relationships within cells.
    Additional Material: 9 Ill.
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    URL: http://dx.doi.org/10.1002/cm.970140410
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    The cytoskeleton of the naked green flagellate Spermatozopsis similis: Isolation, whole mount elecron microscopy, and preliminary biochemical and immunological characterization (1989)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 14 (1989), S. 552-561 
    Details
    ISSN: 0886-1544
    Keywords: Spermatozopsis ; flagellar roots ; rhizosyndesmos ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The cytoskeleton of the naked, biflagellate green alga Spermatozopsis similis Preisig & Melkonian was isolated by treatment of cells with Nonidet P-40 (0.1%) in lysis buffer (30 mM HEPES, 5 mM EGTA, 15 mM KCl, pH 7) and studied in detail by whole-mount electron microscopy. Isolated cytoskeletons retain the twisted shape of live cells and consist of the two axonemes, the basal apparatus with 4 microtubular and two fibrous roots, and 8-10 secondary cytoskeletal microtubules (SCMT's). The four microtubular flagellar roots differ in number of microtubules (two types with 2 or 5 microtubules, respectively), in their association with fibrous roots of the system I-type (two-stranded roots), in total length (two roots with an average of 4.5 μm and two roots with and average of 7.5 μm), and in length of individual root microtubules. Certain of the root microtubules and most of the SCMT's extend to the posterior end of the cell where they converge, terminate and are interconnected by a fibrous cap-like structure, the rhizosyndesmos. This novel structure consists of a network of 2 nm filaments that presumably lacks centrin as indicated by double immunofluorescence (anti-α-tubulin and anti-centrin) of isolated cytoskeletons. Two-dimensional gel electrophoresis of isolated, purified basal apparatuses of S. similis identifies among other proteins two isoforms of centrin and α- and β-tubulin as intrinsic components.
    Additional Material: 13 Ill.
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    URL: http://dx.doi.org/10.1002/cm.970140412
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    Structural basis of hierarchical multiple substates of a protein. IV: Rearrangements in atom packing and local deformations (1989)
    New York, NY : Wiley-Blackwell
    Proteins: Structure, Function, and Genetics 5 (1989), S. 125-131 
    Details
    ISSN: 0887-3585
    Keywords: protein conformation ; dynamics ; Monte Carlo simulation ; conformational energy ; minimization ; plastic deformation ; conformational heterogeneity ; hierarchy in dynamics ; trypsin inhibitor ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Differences in atom packing are studied in the minimum energy conformations derived from the record of the Monte Carlo simulation of conformational fluctuation in the native state of a globular protein, bovine pancreatic trypsin inhibitor. It is found that local deformations observed among the minima which are found in the previous paper are accompanied by rearrangement of atom packing. Spatial locations of the local deformations in the three-dimensional folded structure are also studied. It is foundthat the local deformations are distributed in space in several clusters inthe folded structure. The size and location of the clusters characterize the respective fluctuations of the first and the second levels observed in the simulation. In the fluctuations of the first level local deformations, each of which usually involves a few side chains and one main chain local segment, are thermally exited independently of each other near thesurface of the molecule. The observed fluctuation of the second level involves a cooperative deformation involving many side chains and local main chain segments all in one cluster, which goes though the core of the molecule. The collective local deformations observed both in the first and second levels are plastic in the sense that they are accompanied with rearrangement of atom packing.
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/prot.340050206
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    Structural principles of α/β barrel proteins: The packing of the interior of the sheet (1989)
    New York, NY : Wiley-Blackwell
    Proteins: Structure, Function, and Genetics 5 (1989), S. 139-148 
    Details
    ISSN: 0887-3585
    Keywords: protein architecture ; packing ; evolutionary relationships ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: α/β barrel structures very similar to that first observed in triose phosphate isomerase are now known to occur in 14 enzymes. To understand the origin of this fold, we analyzed in three of these proteins the geometry of the eight-stranded β-sheets and the packing of the residues at the center of the barrel. The Packingin thisregion is seen in its simplest form in glycolate oxidase. It consists of 12 residues arranged in three layers. Each layer contains four side chains. The packing of RubisCO and TIM can be understood in terms of distortions of this simple pattern, caused by residues with small side chains at someof the positions inside the barrel. Two classes of packing are found. In one class, to which RubisCO and TIM belong, the central layer is formed by a residue from the first, third, fifth, and seventh strands; the upper and lower layers are formed by residues fromthe second, fourth, sixth, and eighth strands. In the second class, to which GAO belongs, this is reversed: it is side chains from the even-numbered strands that form the central layer, and side chains from the oddnumbered strands that form the outer layers. Our results suggest that not all proteins with this fold are related by evolution, but that they represent a common favorable solution to the structural problems involved in the creation of a closed β barrel.
    Additional Material: 8 Ill.
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    URL: http://dx.doi.org/10.1002/prot.340050208
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    Rebuilding flavodoxin from Cα coordinates: A test study (1989)
    New York, NY : Wiley-Blackwell
    Proteins: Structure, Function, and Genetics 5 (1989), S. 170-182 
    Details
    ISSN: 0887-3585
    Keywords: modeling ; flavodoxin ; structure prediction ; side chains ; database ; structure analysis ; protein ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The tertiary structure of flavodoxin has been model build from only the X-ray crystallographic α-carbon coordinates. Main-Chain atoms were generated from a dictionary of backbone structures. Side-chain conformations were initially set according to observed statistical distributions, clashes were resolved with reference to other knowledge-based parameters, and finally, energy minimization was applied. The RMSD of the model was 1.7 Å across all atoms to the native structure. Regular secondary structural elements were modeledmore accurately than other regions. About 40%of the ξ1 torsional angles were modeled correctly. Packing of side chains in the core was energetically stable but diverged significantly from the native structure in some regions.The modeling of protein structures is increasing in popularity but relatively few checks have been applied to determine the accuracy of the approach. In this work a variety of parameters have been examined. It was found that close contact, and hydrogen-bonding patterns could identifypoorly packed residues. These tests, however, did not indicate which residues had a conformation different from the native structure or how to move such residues to bring them into agreement. To assist in the modeling of interacting side chains a database of known interactions has been prepared.
    Additional Material: 8 Ill.
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    URL: http://dx.doi.org/10.1002/prot.340050212
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    The 15 N-terminal amino acids of hexokinase II are not required for in vivo function: Analysis of a truncated form of hexokinase II in Saccharomyces cerevisiae (1989)
    New York, NY : Wiley-Blackwell
    Proteins: Structure, Function, and Genetics 5 (1989), S. 218-223 
    Details
    ISSN: 0887-3585
    Keywords: yeast hexokinase II ; dimerization ; in vivo functions ; glucose repression ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The function of the N-terminal amino acids of Saccharomyces cerevisiae hexokinase II was studied in vivo using strains producing a form of hexokinase II lacking its first 15 amino acids (short form).This short form of hexokinase II was produced from a fusion between the promoter region of the PGK1 gene and the HXK2 coding sequence except the first 15 codons. As expected, the in vitro analysis of the short from protein by gel filtration chromatography indicates that the short protein does not form dimers under conditions where the wild-type protein dimerizes. Kinetic studies show that the enzymatic activities are very similarto wild-type behavior. The physiological experiments performed on the strains containing the fusion allele demonstrate that the short form ofthe enzyme is similar to the wild-type both in terms of phosphorylation of hexoses and glucose repression. We conclude that the N-terminalamino acids of hexokinase II are not required in vivo either for phosporylation of hexoses or for glucose repression.
    Additional Material: 4 Ill.
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    URL: http://dx.doi.org/10.1002/prot.340050305
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    The structure of aconitase (1989)
    New York, NY : Wiley-Blackwell
    Proteins: Structure, Function, and Genetics 5 (1989), S. 289-312 
    Details
    ISSN: 0887-3585
    Keywords: aconitase ; iron-sulfur enzyme ; crystal structure ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The crystal structure of the 80,000 Da Fe—S enzyme aconitase has been solved and refined at 2.1 Å resolution. The protein contains four domains; the first three from the N-terminus are closely associated around the [3Fe-4S] cluster with all three cysteine ligands to the cluster being provided by the third domain. Associationof the larger C-terminal domain with the first three domains createsan extensive cleft leading to the Fe—S cluster. Residues from all four domains contribute to the active site region, which is defined by the Fe—S cluster and a bound SO42-ion. This region of the structure contains 4 Arg, 3 His, 3 Ser, 2 Asp, 1 Glu, 3 Asn, and 1 Gln residues, as well asseveral bound water molecules. Three of these side chains reside on a threeturn 310 helix in the first domain. The SO42-ion is bound 9.3 Å from the center of the [3Fe-4S] cluster by the side chains of 2 Arg and 1 Gln rsidues. Each of 3 His side chains in the putative active site is paired with Asp or Glu side chains.
    Additional Material: 13 Ill.
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    URL: http://dx.doi.org/10.1002/prot.340050406
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    Three-dimensional structure of a fluorescein-Fab complex crystallized in 2-methyl-2,4-pentanediol (1989)
    New York, NY : Wiley-Blackwell
    Proteins: Structure, Function, and Genetics 5 (1989), S. 271-280 
    Details
    ISSN: 0887-3585
    Keywords: antifluorescyl monoclonal antibody ; high-affinity binding site ; effects of MPD on hapten binding ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The crystal structure of a fluorescein-Fab (4-4-20) complex was determined at 2.7 Å resolution by molecularreplacement methods. The starting model was the refined 2.7 Å structure of unliganded Fab from an autoantibody (BV04-01) with specificity for single-stranded DNA. In the 4-4-20 complex fluorescein fits tightly into a relatively deep slot formed by a network of tryptophan and tyrosine side chains. The planar xanthonyl ring of the hapten is accommodated at the bottom of the slot while the phenylcarboxyl group interfaces with solvent. Tyrosine 37 (light chain) and tryptophan 33 (heavy chain) flank the xanthonyl group and tryptophan 101 (light chain) provides the floor of the combining site. Tyrosine 103 (heavy chain) is situated near the phenyl ring of the hapten and tyrosine 102 (heavy chain) forms part of the boundary of the slot. Histidine 31 and arginine 39 of the light chain are located in positions adjacent to the two enolic groups at opposite ends of the xanthonyl ring, and thus account for neutralization of one of two negative charges in the haptenic dianion. Formation of an enol-arginine ion pair in a region of low dielectric constant may account for an incremental increase in affinity of 2-3 orders of magnitude in the 4-4-20 molecules relative to other members of an idiotypic family of monoclonalantifluorescyl antibodies. The phenyl carboxyl group of fluorescein appearsto be hydrogen bonded to the phenolic hydroxyl group of tyrosine 37 of the light chain. A molecule of 2-methyl-2,4-pentanediol (MPD), trapped in the interface of the variable domainsjust below the fluorescein binding site, may be partly responsible for the decrease in affinity for the hapten in MPD.
    Additional Material: 7 Ill.
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    URL: http://dx.doi.org/10.1002/prot.340050404
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    A 3D building blocks approach to analyzing and predicting structure of proteins (1989)
    New York, NY : Wiley-Blackwell
    Proteins: Structure, Function, and Genetics 5 (1989), S. 355-373 
    Details
    ISSN: 0887-3585
    Keywords: protein ; structure ; prediction ; primary ; secondary ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: A new approach is introduced for analyzing and ultimately predicting protein structures, defined at the level of Cα coordinates. We analyze hexamers (oligopeptides of six amino acid residues) and show that their structure tends to concentrate in specific clusters rather than vary continuously. Thus, we can use a limited set ofstandard structural building blocks taken from these clusters as representatives of the repertoire of observed hexamers. We demonstrate that protein structures can be approximated by concatenating such building blocks. We have identified about 100 building blocks by applying clustering algorithms, and have shown that they can “replace” about 76% ofall hexamers in well-refined known proteins with an error of less than 1 Å, and can be joined together to cover 99% of the residues. After replacing each hexamer by a standard building block with similar conformation, we can approximately reconstruct the actual structure by smoothly joining the overlapping building blocks into a full protein. The reconstructed structures show, in most cases, high resemblance to the original structure, although using a limited number of building blocks and local criteria of concatenating them is not likely to produce a very precise global match. Since these building blocks reflect, in many cases, some sequence dependency, it may be possible to use the results of this study as a basis for a protein structure prediction procedure.
    Additional Material: 10 Ill.
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    URL: http://dx.doi.org/10.1002/prot.340050410
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    Molecular dynamics simulations of ribonuclease T1: Comparison of the free enzyme and 2′ GMP-enzyme complex (1989)
    New York, NY : Wiley-Blackwell
    Proteins: Structure, Function, and Genetics 6 (1989), S. 20-31 
    Details
    ISSN: 0887-3585
    Keywords: ribonuclease ; active site ; conformational change ; protein-nucleic ; acid interactions ; fluorescence depolarization ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Molecular dynamics simulations were performed on free RNase T1 and the 2′GMP-RNase T1 complex in vacuum and with water in the active site along with crystallographically identified waters, allowing analysis of both active site and overall structural and dynamics changes due to the presence of 2′GMP. Difference in the active site include a closing in the presence of 2′GMP, which is accompanied by a decrease in mobility of active site residues. The functional relevance of the active site fluctuations is discussed. 2′GMP alters the motion of Tyr-45, suggesting a role for that residue in providing a hydrophobic environment for the protein-nucleic acid interactions responsible for the specificity of RNase T1. The presence of 2′GMP causes a structural change of the C-terminus of the α-helix, indicating the transmission of structural changes from the active site through the protein matrix. Overall fluctuations of both the free and 2′GMP enzyme forms are in good agreement with X-ray temperature factors. The motion of Trp-59 is influenced by 2′GMP, indicating difference in enzyme dynamics away from the active site, with the calculated changes following those previously seen in time-resolved fluorescence experiments.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prot.340060103
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    Recombinant HIV1 protease secreted by Saccharomyces cerevisiae correctly processes myristylated gag polyprotein (1989)
    New York, NY : Wiley-Blackwell
    Proteins: Structure, Function, and Genetics 6 (1989), S. 324-337 
    Details
    ISSN: 0887-3585
    Keywords: aspartyl protease ; HIV/AIDS ; yeast expression ; polyprotein processing ; α-factor ; secretion ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The protease of the human immunodeficiency virus type I (HIV1) was expressed both intracellularly and extracellularly in Saccharomyces cerevisiae. Intracellular expression of the protease was achieved by fusing a 179 amino acid precursor form of the protease to human superoxide dismutase (hSOD). Self-processing of the viral enzyme from the hybrid precursor was demonstrated to ocur within the yeast host. Secretion of the protease was achieved by fusing the leader sequence of yeast α-factor to the precursor form of the protrease or to the 99 amino acid mature form of the protease. Authentic and active forms of the retroviral enzyme were detected in yeast supernatants of cells expressing the precursor or the mature form of the protease. A D25E active site variant of the retroviral enzyme exhibited diminished autocatalytic activity when expressed intracellularly or secreted from yeast. The wild-type protease was active in an in vitro assay on the natural substrate, myristylated gag precursor, Pr53gag. Correct processing of Pr53gag at the Tyr 138-Pro 139 junction was confirmed by amino terminal sequence analysis of the resulting capsid protein (CA, p24). The secreted protease was purified to homogeneity from yeast media using preparative isoelectric focusing and reverse-phase HPLC. Amino terminal sequence analysis showed a sequence beginning at amino acid 1 of the mature enzyme (Pro) and another sequence beginning at amino acid 6 (Trp). This shorter sequence may represent a natural autolytic product of the proteaseaspartyl protease.
    Additional Material: 7 Ill.
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    URL: http://dx.doi.org/10.1002/prot.340060315
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    Use of restrained molecular dynamics in water to determine three-dimensional protein structure: Prediction of the three-dimensional structure of Ecballium elaterium trypsin inhibitor II (1989)
    New York, NY : Wiley-Blackwell
    Proteins: Structure, Function, and Genetics 6 (1989), S. 405-417 
    Details
    ISSN: 0887-3585
    Keywords: protein tertiary structure ; incorrect and correct folding ; molecular surfaces ; solvation free energy ; solution and crystal structure ; disulfide connectivity determination ; squash inhibitor family ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Refinement of distance geometry (DG) structures of EETI-II (Heitz et al.:Biochemistry 28:2392-2398, 1989), a member of the squash family trypsin inhibitor, have been carried out by restrained molecular dynamics (RMD) in water. The resulting models show better side chain apolar/polar surface ratio and estimated solvation free energy than structures refined “in cacuo.” The consistent lower values of residual NMR constraint violations, apolar/polar surface ration and solvation free energy of one of these refined structures allowed prediction of the 3D folding and disulfide connectivity of EETI-II. Except for the few first residues for which no NMR constraints were available, this computer model fully agree with X-ray structures of CMTI-I (Boe et al.: FEBS Lett. 242:285-292, 1989) and EETI-II complexed with trypsin that appeared after the RMD simulation was completed. Restrained molecular dynamics n water is thus proved to highly valuable for refinement of DG structures Also, the successful use of apolar/polar surface ratio and solvation free energy reinforce the analysis of Novotny et al. (Proteins 4: 19-30, 1988) and shows that these criteria are useful indicators of correct versus misfolded models.
    Additional Material: 8 Ill.
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    URL: http://dx.doi.org/10.1002/prot.340060407
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    Masthead (1989)
    New York, NY : Wiley-Blackwell
    Proteins: Structure, Function, and Genetics 5 (1989) 
    Details
    ISSN: 0887-3585
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prot.340050101
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    Comparing short protein substructures by a method based on backbone torsion angles (1989)
    New York, NY : Wiley-Blackwell
    Proteins: Structure, Function, and Genetics 6 (1989), S. 155-167 
    Details
    ISSN: 0887-3585
    Keywords: protein structure comparison ; dihedral angles ; protein conformation ; hemoglobin structure ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: An efficient algorithm was characterized that determines the similarity in main chain conformation between short protein substructures. The algorithm computes Δt, the root mean square difference in φ and ψ torsion angles over a small number of amino acids (typically 3-5). Using this algorithm, large number of protein substrates comparisons were feasible. The parameter Δt was sensitive to variations in local protein conformation, and it correlates with Δr, the root mean square deviation in atomic coordinates. Values for Δt were obtained that define similarity thresholds, which determine whether two substructure are considered structurally similar. To set a lower bound on the similarity threshold, we estimated the component of Δt due to measurement noise fromcomparisons of independently refined coordinates of the same protein. A sample distribution of Δt from nonhomologous protein comparisons identified an upper bound on the similarity threshold, one that refrains from incorporating large numbers of nonmatching comparisons large numbers of nonmatching comparisons. Unlike methods based on Cα atoms alone, Δt was sensitive to rotations in the peptide plane, shown to occur in several proteins. Comparisons of homologus proteins by Δt showed that the active site torsion angles are highly conserved. The Δt method was applied to the α-chain of human hemoglobin, where it readily demonstrated the local differences in the structures of different ligation states.
    Additional Material: 8 Ill.
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    URL: http://dx.doi.org/10.1002/prot.340060206
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    A computer model to dynamically simulate protein folding: Studies with crambin (1989)
    New York, NY : Wiley-Blackwell
    Proteins: Structure, Function, and Genetics 6 (1989), S. 193-209 
    Details
    ISSN: 0887-3585
    Keywords: protein folding ; simulated annealing ; empirical potentials ; Monte Carlo dynamics ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The current work describes a simplified representation of protein structure with uses in the simulation of protein folding. The model assumes that a protein can be represented by a freely rotating rigid chain with a single atom approximately the effect of each side chains. Potentials describing the attraction or repulsion between different types of amino acids are determined directly from the distribution of amino acids in the database of known protein structures. The optimization technique of simulated annealinghas been used to dynamically sample the conformations available to this sample model, allowing the protein to evolve from an extended, random coil into a compact globular structure. Many characteristics expected of true proteins, such as the sequence-dependent formation of secondary structure, the partitioning of hydrophobic residues, and specific disulfide, suggestion the model may accurately simulate the folding process.
    Additional Material: 8 Ill.
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    URL: http://dx.doi.org/10.1002/prot.340060208
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    The carboxyl terminal domain of Escherichia coli DNA topoisomerase I confers higher affinity to DNA (1989)
    New York, NY : Wiley-Blackwell
    Proteins: Structure, Function, and Genetics 6 (1989), S. 249-258 
    Details
    ISSN: 0887-3585
    Keywords: DNA binding domain ; etheno-M13 DNA ; single-stranded DNA affinity chromatography ; proteolytic fragments ; truncated topoisomerase ; protein-DNA interaction ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Limited digestion of E. coli DNA topoisomerase I with trypsin or papain generated a DNA-binding domain of MW 14,000 corresponding to the carboxyl terminal of the enzyme. This fragment binds to single-stranded DNA agarose as tightly as the intact enzyme. It required around 400 mM NaCl for elution. A truncated topoisomerase that lacks this C-terminal domain was purified. It was eluted from the single-stranded DNA agarose column at around 150 mM NaCl. Although the truncated enzyme could relax negatively supercoiled DNA as efficiently as the intact enzyme at low ionic strength, its processivity was more sensitive to increasing salt concentration. Measurement of binding to fluorescent etheno-M13 DNA also demonstrated that the presence of the C-terminal domain confers higher affinity to DNA for the enzyme.
    Additional Material: 5 Ill.
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    URL: http://dx.doi.org/10.1002/prot.340060307
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    Substrate specificities in class A β-lactamases: Preference for penams vs. cephams. The role of residues 237 (1989)
    New York, NY : Wiley-Blackwell
    Proteins: Structure, Function, and Genetics 6 (1989), S. 275-283 
    Details
    ISSN: 0887-3585
    Keywords: mutagenesis ; structure-function relationships ; enzymatic catalysis ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Site saturation mutagenesis has been carried out at Ala-237 in RTEM-1 β-lactamase to assess the role of this site in modulating differences in specificity of β-lactamases for penams vs. cephams as substrates. (An Ala-237 Thr mutation had previously been shown to increase activity on cephems by about 30-80%.1,2) Screening of all 19 possibles mutants on penams and cephems revealed the even more active Ala-237 Asn mutant. Detailed kinnetic analysis showns that this mutant has about four times the activity toward cephalothin and cephalosporin C as the wild-type enzyme. Both mutations reduce the activity toward penams to about 10% that of RETM-1 β-lactamase and lower by about 5°C the tempreature at which the enzyme denatures. Functional properties of the other mutants have also been surveyed. The most intresting aspect of these results is that two quite disparate amino acids, theronine and asparagine, when intorduced for Ala-237, cause such similar changes in enzyme specificity while more similar residues do not alter the catalytic properties of the enzyme to such a significant degree.
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/prot.340060310
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    Axial ligand replacement in horse heart cytochrome c by semisynthesis (1989)
    New York, NY : Wiley-Blackwell
    Proteins: Structure, Function, and Genetics 6 (1989), S. 338-340 
    Details
    ISSN: 0887-3585
    Keywords: cytochrome c ; axial ligand ; semisynthesis ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Semisynthesis has been employed to replace the axial methionine in horse heart cytochrome c with histidine. The reduction potential of the His-80 protein (cyt c-His-80) is 41 mV vs NHE (0.1 M phosphate; pH 7.0; 25°C). The absorption spectra of oxidized and reduced cyt c-His-80 are very similar to those of the native protein in the porphyrin region, but the 695 nm band is absent in the oxidized His-80 protein.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prot.340060316
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    Masthead (1989)
    New York, NY : Wiley-Blackwell
    Proteins: Structure, Function, and Genetics 6 (1989) 
    Details
    ISSN: 0887-3585
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prot.340060401
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    Deletions and replacements of omega loops in yeast iso-1-cytochrome c (1989)
    New York, NY : Wiley-Blackwell
    Proteins: Structure, Function, and Genetics 6 (1989), S. 372-381 
    Details
    ISSN: 0887-3585
    Keywords: cytochromec ; Saccharomyces cerevisiae ; protein secondary structures ; protein design ; protein engineering ; protein folding ; protein evolution ; modular exchange ; loop swap ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Ω(Omega)-loops are protein secondary structural elements having small distance between segment termini. It should be possible to delete or replace certain of these Ω-loops without greatly distorting the overall structure of the remaining portion of the molecule. Functional requirements of regions of iso-1-cytochrome c from the yeast Saccharomyces cerevisiae were in investigated by determining the biosynthesis and activity in vivo of mutant forms in which four different Ω-loops were individually deleted, or in which one Ω-loop was replaced with five different segments. Deletion encompassing amino acid positions 27-33 and79-83 either prevented synthesis of the holoprotein, or produced highly labile iso-1-cytochromes c, whereas deletions encompassing position 42-45 and 48-55 allowed partial synthesis and activity. These two latter regions, therefore, are not absolutely required for any biosynthetic process such as heme attachment, mitochondrial import, or for enzymatic interactions. All replacements in Loop A (residue position 24-33) with the same size (10 amino acid residues), longer (13 and 15 amino acid residues), or shorter segments (6 amino acid residues), resulted in strains having at least partial levels of iso-1-cytochrome c; however, the relative activities ranged from zero to almost the normal level. Thus, Loop A does not appear to be essential for such biosynthetic steps as heme attachment and mitochondrial import. In contrast, the full range of relative activities suggest that this region interacts with physiological partners to carry out efficient electron transport.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prot.340060404
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  • 92
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    The surface area of monomeric proteins: Significance of power law behavior (1989)
    New York, NY : Wiley-Blackwell
    Proteins: Structure, Function, and Genetics 6 (1989), S. 418-423 
    Details
    ISSN: 0887-3585
    Keywords: accessible area ; power law fit ; bootstrap analyses ; fractal structure ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The coefficients in a power low fit of accessible area versus molecular weight for high-reslution monomeric protein structures are assessed with respect to statistical accuracy using bootstrap analyses, and with respect to physical significance using model systems and the concept of roughness or fractal structure of the protein surface.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prot.340060408
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  • 93
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    Electronic Resource
    Masthead (1989)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 12 (1989) 
    Details
    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
    URL: http://dx.doi.org/10.1002/cm.970120301
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  • 94
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    Electronic Resource
    Expression and mutation of Ca2+ ATPases of the sarcoplasmic reticulum (1989)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 14 (1989), S. 26-34 
    Details
    ISSN: 0886-1544
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970140107
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  • 95
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    Electronic Resource
    Actin structure-function relationships in vitro using oligodeoxynucleotide-directed site-specific mutagenesis (1989)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 14 (1989), S. 35-39 
    Details
    ISSN: 0886-1544
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970140108
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  • 96
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    Electronic Resource
    The study of cytoskeletal proteins and mitosis using Aspergillus molecular genetics (1989)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 14 (1989), S. 58-61 
    Details
    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
    URL: http://dx.doi.org/10.1002/cm.970140112
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  • 97
    Electronic Resource
    Electronic Resource
    Organizing microtubules in the cytoplasm: Genetic approaches in yeast and animal cells (1989)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 14 (1989), S. 50-57 
    Details
    ISSN: 0886-1544
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970140111
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  • 98
    Electronic Resource
    Electronic Resource
    Theory for epithelial-mesenchymal transformation based on the “fixed cortex” cell motility model (1989)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 14 (1989), S. 455-457 
    Details
    ISSN: 0886-1544
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970140403
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  • 99
    Electronic Resource
    Electronic Resource
    Cell migration into neural tube lumen provides evidence for the “fixed cortex” theory of cell motility (1989)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 14 (1989), S. 469-484 
    Details
    ISSN: 0886-1544
    Keywords: “fixed cortex” model ; neural crest ; mesenchyme ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: We present a model of cell motility based on emigration of neural crest cells into the neural tube lumen under in vitro conditions (10% fetal calf serum or YIGSR) that inhibit their normal emigration from the base of the neuroepithelium into surrounding extracellular matrix (ECM). Ultrastructural observations reveal that cells lining the lumen are joined by zonulae adherentes (ZA), which are points of strong intercellular attachment, and thereby serve as markers for fixed regions of plasmalemma and cortical actin. Three major observations of the relationship of cells to the ZA support the “fixed cortex” model of mesenchymal cell migration. First, cells extend apical cel processes past the ZA into the lumen. To do this, they must make new apical plasmalemma and actin corrtex that the endoplasm slides into. Second, elongated cells are observed in the lumen that are still attached via ZA to the neuroepithelium. This indicates that all of the endoplasm finally slides past the ZA. Third, numerous cytoplasmic pieces, often attached to each other and to the neuroepithelium via ZA, are found at the site where cells appear to have detached from the epithelium after entering the lumen. Since the ZA is fixed in location, the endoplasm must have slid past it into newly manufactured anterior cortex and plasmalemma, with the trailing end of the cell finally snapping off. The “fixed cortex” theory of cell migration agrees with existing data in that it predicts the polarized insertion of new plasmalemma and actin at the leading end of the cell, but it differs significantly from existing theories of mesenchymal cell migration in that it states that the cell surface remains firmly attached to the substratum while the myosin-rich endoplasm slides past it.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970140405
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  • 100
    Electronic Resource
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    Preparation of microtubules from rat liver and testis: Cytoplasmic dynein is a major microtubule associated protein (1989)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 14 (1989), S. 491-500 
    Details
    ISSN: 0886-1544
    Keywords: intracellular motility ; endocytosis ; cytoskeleton ; ATPase ; retrograde transport ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A microtubule associated protein from brain tissue (MAP 1C), has been found to possess many properties in common with ciliary and flagellar dyneins (Paschal et al.: J. Cell Biol. 105:1273-1282, 1987). However, this protein, now designated as cytoplasmic dynein, exhibited several properties which distinguish it from axonemal forms of the enzyme. We have investigated these characteristics further in a study of cytoplasmic dyneins from non-neuronal tissues. Rat liver and testis in particular were found to contain high levels of cytoplasmic dynein. The yield of dynein from testis was over 70 μg/g of tissue, making this the best source of cytoplasmic dynein of all tissues so far examined. The characterization of dynein from these sources has confirmed and extended our previous observations concerning the unique properties of cytoplasmic dynein. Activation of liver and testis dynein occured at low (〈1 mg/ml) tubulin concentration. Polypeptides identified as subunits of brain cytoplasmic dynein (74, 59, 57, 55, and 53 kDa) were present in liver and testis preparations. In addition, polypeptides at 150 and 45 kDa were found to copurify with the non-neuronal dyneins. The liver and testis enzyme hydrolyzed pyrimidine nucleotides at rates up to 12.5 times faster than ATP, though the relative affinity of cytoplasmic dynein for CTP was much lower (Km = 1.0 mM) than that for ATP. The properties of the testis enzyme were consistent with its identification as a cytoplasmic dynein rather than a sperm axonemal precursor. These data indicate that cytoplasmic dyneins may be widespread in distribution and that they share certain biochemical properties unique from those of axonemal dyneins. These characteristics are consistent with the proposal that cytoplasmic dynein plays a universal role in retrograde organelle motility.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970140407
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