Snail Helix Pomatia Research Articles

D-[3H]Lysergic acid diethylamide binding to serotonin receptors in the molluscan nervous system.

d-[3H]Lysergic acid diethylamide (LSD) bound to both dopamine- and serotonin (5HT)-sensitive sites in a particulate fraction derived from the central nervous system of the snail Helix pomatia. Conditions were found which enabled the two sites to be studied independently. [3H]LSD appeared to have a slightly higher affinity for dopamine-sensitive binding (Kd = 0.5 nM) than for 5HT-sensitive binding (Kd = 1.2 nM). A pharmacological analysis of the binding indicated that while dopamine- and 5HT-related agonists clearly discriminated between the two sites, putative antagonists showed little specificity for dopamine- or 5HT-sensitive binding. The pharmacology of 5HR-sensitive [3H]LSD binding was studied in relation to a 5HT-sensitive adenylate cyclase present in a particulate fraction derived from the same tissue. There was a very good correlation between the abilities of a range of agents to act as agonists or antagonists in the 5HT-sensitive adenylate cyclase assay and their abilities to displace 5HT-sensitive [3H]LSD binding (r = 0.94; p less than 0.001). In particular, d-LSD and a number of neurologic drugs were inhibitory in both assays in a stereoselective manner. These data suggest that in molluscan tissues, 5HT-sensitive [3H]LSD binding is related to the 5HT receptor which is coupled to adenylate cyclase.

Thymocyte-neuron antigenic correlation: Anti-thymocyte membrane antibodies modify bioelectrical activity of Helix pomatia neurons

The snail ( Helix pomatia) suboesophageal ganglionic complex treated in vitro with rabbit anti-rat thymocyte membrane (ATM) antibodies was used as an immunoneurological model to study the functional relationship between the thymocyte and neuron. Intracellular recordings were made from pacemaker (spontaneously active) and non-pacemaker (silent) neurons before and after application of ATM antibodies. ATM antibodies induced significant changes of the membrane potential, spike amplitude and firing patterns of both pacemaker and non-pacemaker neurons. This is the first demontration that anti-thymocyte antibodies are capable of modifying the bioelectrical activity of the neuron.

Genesis and maturation of serotonergic vesicles in identified giant cerebral neuron of Aplysia.

ArticlesGenesis and maturation of serotonergic vesicles in identified giant cerebral neuron of AplysiaL. J. Shkolnik, and J. H. SchwartzL. J. Shkolnik, and J. H. SchwartzPublished Online:01 Apr 1980https://doi.org/10.1152/jn.1980.43.4.945MoreSectionsPDF (5 MB)Download PDF ToolsExport citationAdd to favoritesGet permissionsTrack citations ShareShare onFacebookTwitterLinkedInEmailWeChat Previous Back to Top Next Download PDF FiguresReferencesRelatedInformationCited ByFunctional compartmentalization of energy production in neural tissueBrain Research, Vol. 585, No. 1-2Characterization of synaptophysin and G proteins in synaptic vesicles and plasma membrane ofAplysia californicaBrain Research, Vol. 508, No. 2Autoradiographic localization and characterization of [125I]Lysergic acid diethylamide binding to serotonin receptors in AplysiaNeuroscience, Vol. 24, No. 3Changes in serotonin concentration in a living neurone: a study by on-line intracellular voltammetryBrain Research, Vol. 414, No. 1Selective in vivo labelling of serotonergic neurones by 5,6-dihydroxytryptamine in the snail Helix pomatia LComparative Biochemistry and Physiology Part C: Comparative Pharmacology, Vol. 85, No. 2Distribution of serotonin-immunoreactivity in juvenile AplysiaNeuroscience, Vol. 11, No. 2Uptake of [3H]serotonin in the abdominal ganglion ofAplysia california. Further studies on the morphological and biochemical basis of presynaptic facilitationBrain Research, Vol. 272, No. 1Retrograde axonal transport of a wheat germ agglutinin-horseradish peroxidase conjugate in aplysia californicaBrain Research, Vol. 244, No. 2Specificity of axonal transport in C2, a histaminergic neuron of Aplysia californicaBrain Research, Vol. 242, No. 1Ultrastructure of a histaminergic synapse inAplysiaBrain Research, Vol. 238, No. 1Molecular diffusion cannot account for spreading of isotope distribution peaks during rapid axoplasmic transportBrain Research, Vol. 216, No. 1Distribution of membrane glycoproteins among the organelles of a single identified neuronm of aplysia. II. isolation and characterization of a glycoprotein associated with vesiclesBrain Research, Vol. 207, No. 1Development of the central nervous system of Aplysia in terms of the differentiation of its specific identifiable cellsNeuroscience, Vol. 5, No. 12 More from this issue > Volume 43Issue 4April 1980Pages 945-967 Copyright & PermissionsCopyright © 1980 the American Physiological Societyhttps://doi.org/10.1152/jn.1980.43.4.945PubMed7359183History Published online 1 April 1980 Published in print 1 April 1980 Metrics

337 - Properties of single calcium channels in the neuronal membrane

The neurons of snail Helix pomatia were internally dialysed and the current through the small electrically isolated patches of the membrane was measured under voltage clamp. The area of the patches was between 30–300 μm 2 (from 1/1000 to 1/100 of the cell surface). The analysis of current fluctuations was used to measure the characteristics of a single calcium channel. The measurements were performed under conditions ensuring the saturation of the calcium channels; the external solution contained 130 m M of Ba 2+. The power density spectra of the barium current fluctuations fitted a spectral density function of the Lorentz form which is characteristic of a single time constant process. The time constant obtained demonstrated no dependence on either the membrane voltage or on the acting conductance value. The value of the time constant was 0.7 ± 0.2 ms [standard error (S.E.) of mean]. No distinct I/f noise component was found. The current flowing through a single calcium channel had the value (for the transfer of Ba 2+ ions) 0.20 ± 0.02 pA (S.E.). The single channel current did not depend on either the membrane potential (since the equilibrium potential was very high) or on the inactivation. The maximum calcium inward current which flows through a single calcium channel is around 0.1 pA and corresponds to a conductance of 0.5 pS.

Helix pomatia agglutinin (HpA) affinity chromatography: The isolation of pure B and T cell populations and their use for the routine HLA-DR (Ia) serology

The anti-A 1 agglutinin (HpA) of the albumin gland of the snail Helix pomatia binds specifically to neuraminidase-treated T lymphocytes. After its immobilization on Sepharose-6MB an affinity matrix is obtained which is able to separate T and B lymphocytes. In 40 independent experiments enriched T and B cell populations were isolated either by this HpA affinity technique or by E-rosettes incubated with sheep red blood cells for 2 h or 15 h. The results showed that with the HpA affinity matrix within 3 h a highly enriched B cell population is isolated with a purity of 80% and a yield of 65%. Since the separation is done within a short period of time and under gentle conditions the percentage of dead cells is not more than 5%, which is a requirement when the cells are to be used for immunofluorescence studies of surface markers and serological determinations involving microscopical scoring. Typing for HLA-A, B, C antigens and for HLA-DR alloantigens can be done on the same day by cytotoxicity assay. The method also provides a clear-cut distinction between the HLA-A, B, C antibodies and the HLA-DR antibodies.

Metabolism of nutrients during intestinal absorption in Helix pomatia and Arion empiricorum (Gastropoda: Pulmonata)

1. 1. Metabolic conversion of l-glutamic acid, l-lysine and d-glucose was investigated after incubation in vitro of isolated intestinal segments of the slug Arion empiricorum and the snail Helix pomatia. 2. 2. When the test compound was l-glutamic acid it was seen that most of the radioactivity of the intestinal extract of both animals corresponded to breakdown products of this amino acid. 3. 3. Using d-glucose as a precursor the incorporation of labelled carbon into nonessential amino acids was observed. 4. 4. No labelled intermediates other than lysine itself were recovered from the l-lysine experiments.

Gating current of calcium channels in the neuronal membrane

Two components of asymmetric displacement current have been distinguished in the membrane of the neurones from the snail Helix pomatia. One of them was irreversibly blocked by intracellular fluoride together with calcium inward current. Another component responsible for much smaller charge movement was resistive to fluoride. The fluoridesensitive asymmetric displacement current appeared to be related to the activity of calcium channels. The normalized steady-state voltage distribution curve of displaced charge coincided with the curve of the square root of normalized calcium conductance (equivalent to m∞ for the m2 model). The maximum logarithmic voltage sensitivity was: 4 mV per e-fold change for calcium conductance and 8 mV for charge distribution. Thus, the effective valencies were close to 6 for calcium conductance and to 3 for charge distribution suggesting 2 gating particles per calcium channel. On-process of calcium current was perfectly fitted to m2 kinetics. The time constants τm correponded to the time constants τon of the asymmetry current exponential decay in a wide range of test voltages. This correspondence failed only at low depolarizations where τm exceeded τon. Conclusion is made that fluoride-sensitive asymmetric displacement current is the gating current of calcium channels.

Properties of single calcium channels in the neuronal membrane

The neurons of snail Helix pomatia were internally dialysed and the current through the small electrically isolated patches of the membrane was measured under voltage clamp. The area of the patches was between 30–300 μm2 (from 1/1000 to 1/100 of the cell surface). The analysis of current fluctuations was used to measure the characteristics of a single calcium channel. The measurements were performed under conditions ensuring the saturation of the calcium channels: the external solution contained 130 mM of Ba2+. The power density spectra of the barium current flucuations fitted a spectral density function of the Lorentz form which is characteristic of a single time constant process. The time constant obtained demonstrated no dependence on either the membrane voltage or on the acting conductance value. The value of the time constant was 0.7±0.2 ms [standard error (S.E.) of mean]. No distinct I/f noise component was found. The current flowing through a single calcium channel had the value (for the transfer of Ba2+ ions) 0.20±0.02 pA (S.E.). The single channel current did not depend on either the membrane potential (since the equilibrium potential was very high) or on the inactivation. The maximum calcium inward current which flows through a single calcium channel is aroud 0.1 pA and corresponds to a conductance of 0.5 pS.

Molluscan immunity: Interactions between the immunogenic bacterium Pseudomonas aeruginosa and the internal defense system of the snail Helix pomatia

Pseudomonas aeruginosa, which can induce elevated immunity in Helix, is agglutinated by the snail plasma. Helix clears this microbe from its circulation in typical fashion; clearance kinetics may be slightly more rapid in immunized snails. Such snails may also be more efficient at killing P. aeruginosa in the digestive gland.

Modulation of the endogenous electrical activity of the bursting neuron in the snail Helix pomatia—III. A factor modulating the endogenous electrical activity of the bursting neuron

A substance (modulating factor) which evokes the appearance of membrane potential waves in the bursting neuron RPa1 from an aestivating snail or an increase of the wave amplitude in the bursting neuron from an active snail ( Helix pomatia) has been found in the snail's brain. This factor also modulates the activity of the bursting neuron V7. The modulating factor was eluted in the exchange volume on Sephadex G-25. The application of the factor led to the development of a depolarizing current at the holding potential −55 mV under voltage clamp conditions. Hyperpolarization of the neuronal membrane from this holding potential by 7 mV for 2 s evoked an inward current before application of the modulating factor and an outward current after its application. No effect of the factor on the electrical activity of other silent or beating neurons were found. It is suggested that modulating factor may be the neurosecretory substance involved in interneuronal communication in the snail brain.

Modulation of the endogenous electrical activity of the bursting neuron in the snail Helix pomatia—I. The generator of the slow rhythms

Electrical activity of the bursting neuron RPal of the snail Helix pomatia was found to be subjected to periodic modulation with an interval of about 100s. The modulation was produced by waves of membrane potential the amplitude of which could change and the bursting activity could be even transformed into the beating one. Clamping the membrane potential in this neuron revealed a periodic slow inward current which appears to cause the modulation of the neuron's electrical activity. The exogenous nature of the generator of the slow inward current in the neuron RPa1 and in other studied neurons was demonstrated. Decrease in the extracellular calcium ion concentration from 10 to 0.4 mM, with a simultaneous increase of magnesium ion concentration from 4 to 14 mM, caused no marked changes in the periodicity of the slow inward current. Decrease in the extracellular sodium ion concentration from 100 to 50 mM increased the interval between the phases of slow inward current and finally led to the complete disappearance of the current. It is suggested that a neurosecretory interneuronal communication exists in the snail brain which has a different mechanism from conventional synaptic transmission.

Modulation of the endogenous electrical activity of the bursting neuron in the snail Helix pomatia—II. The membrane characteristics related to modulation of the endogenous activity of the neuron

The relation of the amplitude of the slow inward current to the holding potential and the changes of membrane conductance during the development of the slow inward current under voltage clamp conditions were investigated on neurons RPa1 and RPa7. The amplitude of the slow inward current in neuron RPa1 linearly increased with membrane hyperpolarization from −30 to −90 mV. The equilibrium potential for the slow inward current found by extrapolation was about +45 mV. In neuron RPa1 rectangular hyperpolarizing pulses (7 mV, 2s), applied from a holding potential of −60 mV, evoked inward currents before the development of the slow inward current and outward currents at the maximum of the slow inward current. These currents decreased with time. In the neuron RPa7 no relation of the amplitude of the slow inward current to holding potentials between −58 and −78 mV and no changes of membrane conductance during the development of the slow inward current were found. It is concluded that the slow inward current in neuron RPa1 is due to an increase of the membrane's sodium permeability. During the development of the slow inward current an additional potential- and time-dependent increase in permeability occurs upon hyperpolarization, obviously to potassium or chloride ions.

In vitro experiments on the accumulation and release of 14C-histamine by snail ( helix pomatia) nervous tissue

When isolated snail ganglia were incubated at 25° in a medium containing 14C-histamine, tissue:medium ratios of about 4 were obtained after only 5 min. Metabolism of the accumulated amine is rapid, for even within this short incubation period, 20 per cent of the substance was metabolised. The process responsible for this accumulation showed properties of an active transport system: it was temperature-sensitive, sodium dependent, and particularly inhibited by ouabain, phenoxybenzamine, chlorpromazine and desimipramine. The accumulation of 14C-histamine showed saturation kinetics typical of a carrier-mediated process and can be divided into sodium-sensitive and -insensitive components. Kinetic analysis of the data revealed similar K m values for both sodium-sensitive and sodium-insensitive plus -sensitive components, i.e. 10 −5 M. A rapid efflux of radioactivity from tissue loaded with 14C-histamine was observed when exposed to 70 mM KCl. This release was inhibited when the calcium content in the medium was replaced by sucrose. Moreover, cobalt ions added to the incubation medium counteracted the effect of KCl. The discussion of the present results is based on the hypothesis that histamine has a transmitter function in the snail CNS.

Synaptic and hormonal modulation of a neuronal oscillator: a search for molecular mechanisms.

1. The central ganglia of a number of gastropod molluscs (including the marine snail Aplysia californica and the terrestrial snail Helix pomatia) contain neurones which exhibit endogenous patterns of oscillatory activity. 2. This oscillatory activity can be modulated for long periods of time by synaptic and hormonal stimulation. 3. Stimulation of appropriate pre-synaptic nerves causes long-lasting hyperpolarization in these neurones, with complete abolition of oscillatory activity. This synaptic response is mediated by an increase in K+ conductance, together with a decrease in inward (Na+/Ca2+) conductance. The ionic conductances affected by synaptic stimulation are those responsible for producing the rhythmic oscillations. 4. The oscillatory activity can also be modulated by the vertebrate neurohyophyseal peptides, vasopressin and oxytocin, and by an endogenous peptide-containing extract of molluscan ganglia. In contrast to synaptic stimulation, these agents cause an increase in oscillatory activity. 5. The endogenous molluscan factor which produces an increase in oscillatory activity can be purified by affinity chromatography on bovine neurophysin linked to Sepharose. This indicates that the molluscan nervous system may contain a neurohypophyseal-like peptide. 6. Oscillatory activity can be modulated by manipulation of cyclic nucleotide metabolism in these neurones. Increases in cAMP alone are associated with abolition of oscillatory activity; this mimics long-lasting synaptic hyperpolarization. Increases in cAMP and cGMP together are associated with an increase in oscillatory activity and mimic the effects of the vertebrate and molluscan peptides. Thus, it is possible that cyclic nucleotides play a role in these physiological responses.

Simultaneous Single Unit Recording in vitro with a Photoetched Laser Deinsulated Gold Multimicroelectrode Surface

Flat photoetched gold conductors 12 ?m wide and 2 ?m thick, situated on a glass plate and deinsulated at their tips with single 8 ns UV laser pulses, have been utilized to record single unit extra-cellular activity from brain ganglia of the snail Helix pomatia. A fixed array of 36 such conductors, terminating in six rows and six columns in a 0.5 mm x 1 mm area, is capable of monitoring simultaneous single unit activity from numerous neurons. Spike amplitudes of 300?500 ?V are generally observed from the predominant 40 ?m diameter cells of these ganglia. Giant neurons usually produce signal amplitudes of over 3 mV that are simultaneously seen by many electrodes. Signals can be monitored by merely resting a locally desheathed ganglion on the recording area under its own weight in a shallow pool of Ringer. A 10 ?m diameter crater in a 3?4 ?m thick insulation layer has an impedance of 2?4 M?at 1 kHz. The capacitance of this metal electrolyte interface is about 0.5 pF/?m2, suggesting that the UV laser produces a partially colloidal gold surface. With this recessed tip design, simultaneous single unit recording from small neurons appears ensured if electrode impedances are below 4 M?, shunt impedances are above 30 M?, and glia cells are not allowed to reinsulate the end of the gold conductor.

Some properties and the axonal transport of choline acetyltransferase in nervous tissue of the snail Helix pomatia

Some properties and the axonal transport of choline acetyltransferase in nervous tissue of the snail Helix pomatia

Degradation of bacterial lipopolysaccharide by gut juice of the snailHelix pomatia

Lipopolysaccharides from several bacteria were selectively degarded by gut juice of the snail Helix pomatia with extensive loss of anticomplementary activity and changes in the electrophoretic pattern in polyacrylamide gels. The gut juice had little effect on ketodeoxyoctonate content or immunodominant sugars. The lipid A moiety of the lipopolysaccharide appeared to be the main site of attack.

Mutagenicity of plant flavonols in the Salmonella/mammalian microsome test: Activation of flavonol glycosides by mixed glycosidases from rat cecal bacteria and other sources

Over 70 naturally occurring and synthetic flavonoids were screened for mutagenicity with 5 tester strains in the Salmonella/mammalian microsome assay: TA1535, TA100, TA1537, TA1538 and TA98. Frameshift mutagenicity was confined to the flavonols (flavon-3-ols) in strains TA98, TA1537 and TA100. The two most mutagenic flavonols, namely, quercetin (3,3′,4′5,7-pentahydroxyflavone) and kaempferol (3,4′,5,7-tetrahydroxyflavone), exhibiting 12 and 7 revertants/nmol in TA98 respectively, are also the most common flavonols occuring in plants. Other flavonols exhibited less activity (revertants/nmol): galangin (2.0), rhamnetin (0.45), kaempferide (0.24), fisetin (0.14), myricetin (0.12), robinetin (0.06) and morin (0.05). All of these flavonols apparently exhibited significant activation by Aroclor 1254 induced rat-liver microsome preparations (S9). However, subsequent study revealed that only those flavonols either lacking or possessing one B ring hydroxyl group had an absolute requirement for microsomal activation. Alternatively, quercetin with two Bring OH groups is not activated by microsomal enzymes, but by soluble (S100) enzymes from liver which are apparently constitutive and not subject to the usual chemical induction. 3 flavonol glycosides, namely, quercetrin (quercetin-3- O-rhamnoside), rutin (quercetin-3- O-rutinoside) and robinin (kaempferol-3- O-galactosido-rhamnoside-7- O-rhamnoside), were found to be nonmutagenic. They could, however, be activated by a variety of mixed glycosidases incorporated in the usual pour plate procedure. The most effective enzyme mixtures were obtained from rat Cecal bacteria and from the snail Helixpomatia.

Locomotor Activity Patterns of the Roman Garden Snail (Helix Pomatia L.) in Light and Dark Conditions

Locomotor Activity Patterns of the Roman Garden Snail (Helix Pomatia L.) in Light and Dark Conditions

Quantitative description of the slowly inactivated barium current through the somatic membrane of molluscan neurons

The slow-inactivating barium current was recorded under voltage clamp conditions from identified neurons of the snail Helix pomatia. Experimental data were analyzed using the Hodgkin-Huxley equations. The dependence of the steady-state value of the inactivation variable on membrane potential was obtained. Slow-inactivating barium current was found to be proportional to the third power of the activation variable. The time constant of activation is strongly dependent upon the membrane potential.