ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Group
    Nature 284 (1980), S. 377-377 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] SATTERLIE AND SPENCER REPLY- Our article was not intended to give definitive evidence for the taxonomic position of the Cubomedusae. However, judged by the neuromuscular properties of the swimming system of Carybdea, the medusae strongly resemble the scyphomedusae. This similarity is so convincing ...
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 2
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Group
    Nature 223 (1969), S. 1384-1385 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Fig. 1. Ventral view of S. droebachiensis pluteus larva with a suction electrode attached, a.e., Anterior epaulette; s.el., suction electrode; p.e., posterior epaulette. Plutei were held in a dense suspension of algal cells (Dunaliella tertiolecta) by polyethylene suction electrodes (Fig. 1) ...
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 3
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Group
    Nature 281 (1979), S. 141-142 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] In order to determine the structure of the subumbrellar nerve-net of Carybdea we examined both live material and electron micrographs. Bipolar and tripolar neurones form an apparently random network throughout the subumbrella of Carybdea. The diameter of neuntes ranges from 0.2 to 5 ?? while the ...
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 4
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Group
    Nature 233 (1971), S. 490-491 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] The stem of the siphonophore Nanomia bijuga is covered with a layer of epithelio-muscular cells some 45 um thick (Fig. 1); this is far thicker than similar cells in many other cnidarians. The muscle fibrils run longitudinally and are non-striated. Fig. 1 Transverse section of stem of Nanomia, 0.5 ...
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Journal of comparative physiology 144 (1981), S. 401-407 
    ISSN: 1432-1351
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary 1. The action potentials of Polyorchis ‘swimming’ muscle cells have a characteristic square waveform. 2. The depolarizing phase of the action potential is dependent on both Na+ and Ca+ + influx since i) sodium ions must be present in the bathing solution for generation of an action potential; ii) the amplitude of action potentials is increased by increasing the Ca+ + concentration of the bathing medium; iii) cobalt ions rapidly block the action potential. 3. The action potential is resistant to tetrodotoxin in the bathing solution. 4. The durations of action potentials are directly proportional to the size of jellyfish. 5. The times to peak tension of contractions in the subumbrellar muscle sheet are directly related to the durations of the action potentials producing those contractions. 6. Tetraethylammonium ions increase the duration of the plateau phase of action potentials, and increase the duration of the contractions.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Journal of comparative physiology 159 (1986), S. 201-213 
    ISSN: 1432-1351
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary 1. Intracellular recordings from three neuronal systems (swimming motor neurons — SMNs, burster — ‘B’ system, oscillator — ‘O’ system) and two effector systems (swimming and tentacle myoepithelium) are used to demonstrate the mechanism of the Stereotypie shadow reflex of the hydromedusanPolyorchis penicillatus. 2. The two motor systems, SMNs and ‘B’ system which drive swimming muscle and tentacle muscle contractions respectively, spike spontaneously in lighted conditions. At light OFF, these systems depolarize and give a burst of action potentials (Figs. 2a, 3a, b). This response is lost if the ocelli are removed (Figs. 2b, 3c). Neither system showed any bursting activity in response to decreasing light intensity when chemical synapses are blocked by bathing the preparation in excess Mg++ (Figs. 2c, 3d, 4e). 3. The non-spiking ‘O’ system shows regular membrane potential oscillations in lighted conditions. At light OFF, the ‘O’ system rapidly hyperpolarizes and the oscillations cease (Fig. 4a, b). There is a similar response to shadows after the ocelli are removed (Fig. 4c). Even when chemical synapses are blocked by excess Mg++, the ‘O’ system shows a rapid hyperpolarization at light OFF and depolarization at light ON (Fig. 4e). 4. Typical ‘O’ system recordings can be made from deep within the ocellar cup (Fig. 5). 5. ‘B’ system action potentials show a 1∶1 correlation with large EPSPs which can be recorded from the tentacle myoepithelium and epithelium covering the outer nerve-ring (ONR) (Figs. 6–9). These 4–6 mV EPSPs are delayed by 8–10 ms from the peak of the ‘B’ system action potential and are correlated with tentacle contractions. 6. The behavioral sequence of the shadow reflex consists of an initial rapid swimming muscle contraction, followed by several rapid tentacle contractions and is completed by 2–4 additional swimming muscle contractions (Fig. 11).
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Journal of comparative physiology 159 (1986), S. 215-225 
    ISSN: 1432-1351
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary 1. The photosensitive ‘O’ system neurons showed a graded hyperpolarization during various ‘instantaneous’ decreases in light intensity and graded depolarization during increases in light intensity. The ‘O’ system failed to respond to ‘instantaneous’ changes in light intensity of less than about 28% (Fig. 1a). 2. The two motor systems, the SMNs and ‘B’ system which drive swimming muscle and tentacle contractions respectively, showed graded depolarizations and spiking frequencies during various ‘instantaneous’ decreases in light intensity (Fig. 1b, c). Increases in light intensity initially cause hyperpolarizations of these two systems. The SMNs failed to respond to ‘instantaneous’ changes in light intensity of less than about 26% (Fig. 1b). 3. The ‘O’ system and SMNs respond with little habituation to repetitive changes in light intensity. Each system shows a near constant response to ‘instantaneous’ 100% changes in light intensity to all except the lowest light intensities tested (Figs. 2, 3). 4. The rate of ‘O’ system hyperpolization is directly proportional to the rate of percentage decrease in light intensity (Figs. 4, 5, 7a). 5. The SMNs and ‘B’ system show graded depolarizations and changes in spiking frequencies during ‘slow’, continuous decreases in light intensity. These two motor systems also show graded hyperpolizations during ‘slow’ increases in light intensity (Figs. 6, 7). 6. The ‘O’ system neurons show properties common to photoreceptors in general, namely graded responses to light intensity changes and electrical coupling between adjacent cells.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Journal of comparative physiology 148 (1982), S. 353-363 
    ISSN: 1432-1351
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary 1. Postsynaptic potentials can be recorded intracellularly from epitheliomuscular cells overlying the inner nerve-ring in the medusaPolyorchis penicillatus (Cnidaria, Hydrozoa) (Fig. 1). These postsynaptic potentials lead to the generation of muscle action potentials which propagate through the swimming-muscle sheets. It is the swimming motor neuron network that innervates this epithelium. An alternative motor pathway is present that involves a network of small, multipolar neurons that is interpolated between swimming motor neurons and overlying epithelial cells (Fig. 2). 2. That the postsynaptic potentials recorded are due to release of a chemical transmitter is supported by the following evidence: (a) PSPs have a constant delay $$(\bar x = 3.2{\text{ms)}}$$ following the presynaptic spike (Figs. 3, 4); (b) high Mg++ concentrations reduce the amplitude of PSPs and eventually block transmission (Fig. 10); (c) there is no electrical coupling between presynaptic neurons and postsynaptic epithelial cells. 3. There is an inverse relationship between the duration of presynaptic action potentials and the amplitude of PSPs (Figs. 5, 6). The duration of presynaptic action potentials is a reflection of the degree of synchrony of spiking in the motor network so that short duration motor spikes are associated with synchronous firing. In such cases, the simultaneous release of transmitter substance at a number of neighbouring synapses will cause rapid temporal summation of PSPs in postsynaptic cells. Similarly, long duration presynaptic spikes are associated with asynchronous transmitter release and consequently with small PSPs (Figs. 8, 9). 4. Changes in PSP amplitude are seen in all postsynaptic cells of a localised region (Fig. 7). 5. The muscle action potential can be separated into two components, the velar and subumbrellar action potentials (Fig. 11). This biphasic nature of muscle action potentials recorded in the synaptic region results from all-or-none action potentials that are generated at the velar and subumbrellar borders of this region conducting back electrotonically. These action potentials made to conduct antidromically towards the synapses by electrical stimulation of the muscle sheets decrement as they travel through the synaptic region (Fig. 12). The nature of electrical coupling between epithelial cells in the synaptic non-muscular region and the muscle sheets proper must be different. 6. Larger amplitude PSPs are associated with muscle action potentials that follow with a shorter latency, and that have the two components (velar and subumbrellar) following each other more rapidly (Figs. 5, 9). 7. Action potentials in the motor network are brought into phase as they conduct around the margin. This leads to more synchronous activation of synapses and hence larger PSPs at regions distant from the initiation site of the motor spike. The resulting decrease in the latency of muscle APs at these distant sites will automatically compensate for the conduction delay of motor spikes.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 246 (1986), S. 463-479 
    ISSN: 1432-0878
    Keywords: RFamide ; Neuropeptide ; Nervous system ; Siphonophores ; Coelenterates
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary An antiserum to the sequence Arg-Phe-amide (RFamide) was used to stain the nervous systems of various physonectid siphonophores. In the stem of Nanomia bijuga, this antiserum stained an ectodermal nerve net, which was interrupted, at regular intervals, by transverse collars of neurons. Injection of Lucifer yellow into the “giant axon” of the stem showed that this axon was dye-coupled to an ectodermal nerve net that resembled the RFamide-positive network. Ectodermal nets of neurons were also found in the pneumatophore, gastrozooids, tentacles and tentilla. At the junctions of the pneumatophore, the gastrozooids, the dactylozooids and the gonozooids with the stem, and at the junctions of tentacles and tentilla, collars or rings of neurons occurred. The stem was connected to the phyllozooids and nectophores by muscular lamellae, which were bordered by chains of neurons. At the margin of the nectophores, an immunoreactive nerve ring was found. Connected to this ring and located in the“seitliche Zapfen” (“sidely-located patche”), were two agglomerations of nerve cells. On the upper side of the bell margin, positioned at 90° relative to the “seitliche Zapfen”, a delta-shaped neuronal structure was found. This structure was connected to the nerve ring and was associated with a muscle, which ran a short distance along the exumbrellar surface. The nervous systems of Agalma elegans, Forskalia edwardsi, Forskalia leuckarti and Halistemma rubrum resembled that of Nanomia bijuga in all major respects.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Hydrobiologia 216-217 (1991), S. 565-571 
    ISSN: 1573-5117
    Keywords: Hydrozoa ; RF-amides ; neurotransmitter ; immunohistochemistry ; voltage clamp ; FMR-Famides
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A family of peptides with the carboxy-terminus Arg-Phe-amide has been localized to specific subpopulations of neurons in every cnidarian species examined. These neurons are typically sensory in character or are associated with smooth muscle. Although a transmitter role for these peptides has been suggested for anthozoans at neuromuscular synapses, no such evidence is available for hydrozoans. Instead there is evidence that RF-amides can be modulators of neuronal activity which takes the form of a biphasic (inhibitory then excitatory) response in vivo, while in vitro only the inhibitory response is seen. Voltage clamp studies of identified motor neurons showed large, transitory outward currents when Pol-RF-amide peptide was applied.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...