Crustacean Nerve Research Articles

Elucidating the temporal dynamics of optical birefringence changes in crustacean nerves.

Intrinsic optical properties, such as optical birefringence, may serve as a tool for minimally invasive neuroimaging methods with high spatiotemporal resolution to aid in the study of neuronal activation patterns. To facilitate imaging neuronal activity by sensing dynamic birefringence, temporal characteristics behind the signal must be better understood. We have developed a novel nerve chamber to investigate changes in birefringence at the stimulation site, and at distances ~4-28 mm from that site. Using crustacean nerves with either heterogeneous or homogeneous size distributions of axon diameters, we found that the gradual (slow) recovery of the crossed-polarized signal is not explained by the arrival times of action potentials in smaller axons. Through studying the effects of stimulating current and voltage pulses, we hypothesize that the recovery may be caused by a capacitive-like coupling between firing axons and adjacent tissue structures, and we report data consistent with this hypothesis. This study will aid in the utilization of action-potential-related changes in birefringence to study fast changes in neuronal network activity.

Membrane current-based mechanisms for excitability transitions in neurons of the rat mesencephalic trigeminal nuclei

Since Hodgkin's first description of three classes of excitability in crustacean nerve axons (1948), theoretical studies have used mathematical models to demonstrate that small changes in the parameters describing ionic currents could result in transitions between classes of membrane excitability. However, these transitions have rarely been investigated experimentally. Here, we show that states of excitability in rat mesencephalic V (Mes V) neurons can be classified into three groups, with manipulations of the 4-aminopyridine sensitive K + current ( I 4-AP) or persistent Na + current ( I NaP) leading to the corresponding transitions. However, alterations in the hyperpolarization-activated cation current ( I h), tetraethylammonium (TEA)-sensitive K + current, or Cd 2+-sensitive Ca 2+ current were ineffective in causing these transitions. These results provide experimental evidence for the excitability transitions predicted by Hodgkin and characterize their ionic mechanisms in Mes V neurons.

Depth-Resolved Measurement of Transient Structural Changes during Action Potential Propagation

We report noncontact optical measurement of fast transient structural changes in the crustacean nerve during action potential propagation without the need for exogenous chemicals or reflection coatings. The technique, spectral domain optical coherence tomography, provides real-time cross-sectional images of the nerve with micron-scale resolution to select a specific region for functional assessment and interferometric phase sensitivity for subnanometer-scale motion detection. Noncontact optical measurements demonstrate nanometer-scale transient movement on a 1-ms timescale associated with action potential propagation in crayfish and lobster nerves.

Simultaneous birefringence and scattered light measurements reveal anatomical features in isolated crustacean nerve

Simultaneous fast birefringence and scattered light changes associated with crustacean nerve activation have different time courses and are produced by separate biophysical mechanisms. Technological advances in illumination, photodiodes and amplification circuitry achieved better signal-to-noise than earlier studies revealing optical signals in axonal nerve bundles as small as crayfish ventral cord and claw. The birefringence measurements yielded signals that could be observed in single trials, with temporally separated peaks associated with axonal populations of different diameters. A slit aperture placed perpendicular to the nerve reduced the spatial-temporal integration and enhanced the temporal structure of the separate peaks in the birefringence signal. Moving the slit aperture farther from the stimulation point delayed the signal in time, and also enhanced the separation between peaks. Different propagation velocities of the separate peaks provided evidence for at least three neuronal populations in the bundle. These studies underscore the advantages of birefringence over scattering measurements. Application of birefringence methods can optimize non-invasive imaging techniques being developed to detect fast optical responses associated with electrical neural activity in humans.

Remodeling of the proximal segment of crayfish motor nerves following transection.

Transected crustacean motor axons consist of a soma-endowed proximal segment that regenerates and a soma-less distal segment that survives for up to a year. We report on the anatomical remodeling of the proximal segment of phasic motor nerves innervating the deep flexor muscles in the abdomen of adult crayfish following transection. The intact nerve with 10 phasic axons and its two branches with subsets of 6 and 7 of these 10 axons undergo several remodeling changes. First, the transected nerve displays many more and smaller axon profiles than the 6 and 7 axons of the intact nerve, approximately 100 and 300 profiles in the two branches of a preparation transected 8 weeks previously. Serial images of the transected nerve denote that the proliferation of profiles is due to several orders of axon sprouting primary, secondary, and tertiary branches. The greater proliferation of axon sprouts, their smaller size, and the absence of intervening glia in the one nerve branch compared with the other branch denote that sprouting is more advanced in this branch. Second, the axon sprouts are regionally differentiated; thus, although in most regions the sprouts are basically axon-like, with a cytoskeleton of microtubules and peripheral mitochondria, in some regions they appear nerve terminal-like and are characterized by numerous clear synaptic vesicles, a few dense-core vesicles, and dispersed mitochondria. Both regions possess active zone dense bars with clustered synaptic vesicles found opposite other sprouts, glia, hemocytes, and connective tissue, but because the opposing membranes are not differentiated into a synaptic contact, the active zones are extrasynaptic. Third, some of the transected axons display a glial cell nucleus denoting assimilation of an adaxonal glial cell by the transected axons. Fourth, within the nerve trunk are a few myocytes and muscle fibers. These most likely originate from adjoining and intimately connected hemocytes, because such transformation occurs during muscle repair. In a crustacean nerve, however, where muscle is clearly misplaced, its presence implies an instructive role for motor nerves in muscle formation.

Cytotoxic and neurotoxic activities in extracts of marine sponges (Porifera) from southeastern Brazilian coast

This work reports the results of a screening program based on marine sponge extracts from the southeastern Brazilian coast, covering cytotoxic and neurotoxic activities. Polar and non-polar extracts of 24 sponge species collected by scuba diving in rocky shores, from 1996 to 2000, were screened for haemolytic, cytotoxic and neurotoxic activities. Fifty-four percent (13/24) of the sponge extracts tested exhibited from median to high toxicity in at least one of the toxicity bioassays performed. Amphimedon sp. and Arenosclera brasiliensis Muricy and Ribeiro, 1999 induced haemolysis in mice erythrocytes at small concentrations. Aaptos sp. and Geodia corticostylifera Hajdu, Muricy, Custodio, Russo and Peixinho, 1992 extracts lysed the sea-urchin eggs, while Axinella aff. corrugata George and Wilson, 1919, Mycale laxissima Duchassaing and Michelotti, 1864, A. brasiliensis and Raspailia elegans Bourm-Esnauls, 1973, inhibited mitosis and its development. The extracts of G. gibberosa Lamarck, 1815 and Stelletta sp. showed specific neurotoxic activity, while G. corticostylifera and A. brasiliensis extracts induced blockage of action potential conduction in crustacean nerve, maybe due to their lytic properties.

Occurrence of toxins, other than paralysing type, in the skin of tetraodontiformes fish

Puffer fish (Tetraodontidae and Diodontidae) possess paralysing toxins (tetrodotoxin and analogues) that are secreted upon stimulation. In a previous work it was demonstrated that mucous secretion from the puffer fish Sphoeroides spengleri, when mixed in sea water passing through the orobranchial cavity of groupers, induced cardiorespiratory alterations. In the present study, skin secretions from Ciclichthys spinosus, S. spengleri and Diodon hystrix were tested on crustacean nerves, sea urchin eggs and mouse erythrocyte suspensions to verify neurotoxic and cytotoxic activities. Ciclichthys spinosus and D. hystrix secretions induced transient depolarizations with 0.16 mg and blocked crustacean nerve conduction after prolonged exposure. Both secretions had cytotoxic effects: when applied to sea urchin eggs they caused cleavage inhibition and anomalies in a dose-dependent manner ( ed 50 ± S.E.M. = 2.59 ± 0.08 mg/ml for C. spinosus and 1.23 ± 0.07 mg/ml for D. hystrix); moreover, hemolysis occurred with an ed 50 = 0.76 mg/ml of 0.5% mouse erythrocyte suspensions to C. spinosus and 0.59 mg/ml to D. hystrix. These secretions were not lethal in acute toxicity tests, even at 335 mg/ml. The neurotoxic components were thermolabile while the hemolytic activity was resistant to boiling. Tests with the secretion from S. spengleri did not show cytotoxic effects but promptly blocked action potentials of crustacean nerves and were lethal for mice in acute toxicity rests. When applied to groupers, the C. spinosus secretion caused cardiorespiratory alterations. These results suggest the presence of neurotoxins (other than tetrodotoxin) and cytotoxins in skin of diodontid puffer fish.

Effects of black widow spider venom and latrocrustatoxin on crustacean nerve cells: Electrophysiological and ultrastructural study

1. 1. Black widow spider venom (BWSV), or crustacean-specific toxin purified from it (named latrocrustatoxin, LCT) were lethal for the crayfish. 2. 2. Distortions in the EMG and motor activity pattern after LCT injection indicated venom effects on the crayfish nervous system. 3. 3. In the isolated ventral nerve cord, transient activation of the “silent” interneurons and motoneurons occurred after BWSV or LCT application. 4. 4. In the isolated nerve-muscle preparation, LCT application elicited an intense transmitter release resulting in the complete blockade of neuromuscular transmission. 5. 5. Electron microscopic study of the nervous and muscle tissue in venom treated crayfish demonstrated certain destructive changes in the nervous cells especially in the nerve terminals. 6. 6. The results suggest that the LCT acts as a presynaptic neurotoxin in the central and peripheral nervous system of the crayfish.

Activity-induced changes in synaptic release sites at the crayfish neuromuscular junction

Crustacean motor axons provide a model in which activity-dependent changes in synaptic physiology and synaptic structure can be concurrently observed in single identifiable neurons. In response to a train of stimulation, crustacean neuromuscular junctions undergo pronounced facilitation of transmitter release. The effects of maintained high-frequency stimulation may persist for at least several hours ("long-term facilitation"). Electrophysiological studies suggest that the number of "active" synapses contributing transmitter quanta at low frequencies of stimulation increases during and after a train of high-frequency stimulation. However, at different terminal recording sites the effect of stimulation varies, and it was observed that not all released quanta produce a voltage change in the postsynaptic muscle cell. Electron microscopic examinations of serial sections from nerve terminals subjected to stimulation were made to determine whether changes in synaptic structure could be correlated with activity-induced long-lasting enhancement of transmission. A procedure was introduced for marking a recorded terminal with fluorescent polystyrene microspheres, which are visible in electron micrographs of the recording site. Crustacean nerve terminals possess a large number of discrete synapses, a small fraction of which have multiple presynaptic "active zones" (dense bodies with clustered synaptic vesicles, thought to represent sites of evoked transmitter release). In terminals previously stimulated, the proportion of synapses with multiple "active zones" is greater than in control unstimulated terminals. Total synaptic vesicle counts and readily releasable vesicles at synapses are not significantly different in previously stimulated terminals and controls. In terminals fixed during stimulation a few synapses show evidence of division in "active zones," and synaptic vesicle counts are lower than in controls.(ABSTRACT TRUNCATED AT 250 WORDS)

Spider neurotoxins and their neuronal receptors

Abstract

Characterization of peptides in sea anemone venom collected by a novel procedure

Peptide neurotoxins were isolated from the venom obtained by electrical stimulation of the sea anemone Bunodosoma caissarum. This technique allows almost pure venom to be collected, and the animals to survive. Three neurotoxins (assayed on crustacean nerves) were isolated by gel filtration and reversed-phase high performance liquid chromatography. Hemolysins were also detected in the venom. The amino acid sequence of a major neurotoxin BcIII was determined. BcIII has 48 amino acid residues with six half-cystine residues. This sequence has homology with the type 1 long sea anemone neurotoxins. Two minor toxins (BcI and II) have similar amino acid composition and amino-terminal sequences to BcIII.

Activity-dependent recruitment of silent synapses.

At the crayfish neuromuscular junction, a long-lasting enhancement of synaptic transmission can be induced by tetanic stimulation of 10-20 Hz for several minutes. The long-lasting enhancement is presynaptic in origin, because quantal content increases but not quantal size, and is not dependent upon broadening or enlargement of the presynaptic action potential. The enhancement can be selectively blocked by presynaptic injection of agents that inhibit adenylate cyclase or the cyclic AMP-dependent protein kinase. Entry of calcium may not be sufficient in itself to produce the enhancement. Analyses of quantal events using both a simple binomial statistical method, and a more refined method that takes into account the possibility of unequal probabilities of responding units, have shown that the number of responding units increases during the long-lasting enhancement. In addition, there is an increase in the probability of transmitter release at preexisting units. In contrast, during short-term facilitation accompanying repetitive stimulation, response probability increases greatly whereas the number of responding units increases only moderately with frequencies of activation up to 20 Hz, which increase quantal output severalfold. These results indicate that responding units, hypothesized to be transmitting synapses, can be recruited to active transmission from an unresponsive pool by tetanic activity, and that protein phosphorylation is required for long-lasting changes to occur. The existence of an excess of synapses on crustacean nerve terminals is indicated by ultrastructural studies, which invariably show many synapses on the terminals. The number of morphologically defined synapses is always greater than the number of responding units seen in statistical analyses of quantal release for the same recording location.

The effects of temperature on the physiology of crustacean nerves and muscles

1. 1.|The effects of temperature on crustacean motor nerve, muscle and synaptic physiology have been reviewed in terms of passive properties, threshold potentials and response characteristics. 2. 2.|The generation of additional spikes in the peripheral branches of certain axons has been discussed. 3. 3.|Temperature effects on behaviour have been reviewed.

Calitoxin, a neurotoxic peptide from the sea anemone Calliactis parasitica: amino-acid sequence and electrophysiological properties

We have isolated a new toxin, calitoxin (CLX), from the sea anemone Calliactis parasitica whose amino acid sequence differs greatly from that of other sea anemone toxins. The polypeptide chain contains 46 amino acid residues, with a molecular mass of 4886 Da and an isoelectric point at pH 5.4. The amino acid sequence determined by Edman degradation of the reduced, S-carboxymethylated polypeptide chain and tryptic and chymotryptic peptides is Ile-Glu-Cys-Lys-Cys-Glu-Gly-Asp-Ala-Pro-Asp-Leu-Ser-His-Met-Thr-Gly-Thr- Val-Tyr - Phe-Ser-Cys-Lys-Gly-Gly-Asp-Gly-Ser-Trp-Ser-Lys-Cys-Asn-Thr-Tyr-Thr-Ala- Val-Ala - Asp-Cys-Cys-His-Glu-Ala. No cysteine residues were present in the peptide. Similarly to other sea anemone toxins, calitoxin interacts, in crustacean nerve muscle preparations, with axonal and not with muscle membranes, inducing a massive release of neurotransmitter that causes a strong muscle contraction. The low homology of CLX with RP II and ATX II toxins has implications regarding the role played by particular amino acid residues.

Phylogenetic development of myelin glycosphingolipids

Myelin is a highly specialized membrane, which enwraps axons and facilitates saltatory nerve conduction in vertebrates. Galactocerebroside and its sulfate ester, sulfatide, are highly localized in myelin. To understand the role played by these galactosphingolipids we investigated the changes of these myelin-specific compounds during the course of the evolution of myelin. We found that urodele nerve myelin lacks alpha-hydroxy fatty acid-containing galactosphingolipids. Our morphological and physiological studies of urodele nerves indicated that these hydroxy fatty acid-containing galactosphingolipids probably contribute to fast nerve conduction. Also it is suspected that they are involved in the regulation of the thickness of myelin in relation to the size of the axon. In another study, we discovered that glucocerebroside, which has glucose instead of galactose as its carbohydrate component, is abundantly present in the myelin-like sheath membrane of crustacean nerves. Subsequently the phylogenetic studyindicated that galactocerebrosides were limited to the nervous system of deuterostomes, while all protostome nerves contain glucocerebrosides. The role of glucocerebrosides in multilayered membranes and in the conduction velocity of the protostome nervous system is discussed.

Drosophila mutants with opposing effects on nerve excitability: genetic and spatial interactions in repetitive firing.

Drosophila mutants with opposing effects on nerve excitability: genetic and spatial interactions in repetitive firing.B Ganetzky, and C F WuB Ganetzky, and C F WuPublished Online:01 Mar 1982https://doi.org/10.1152/jn.1982.47.3.501MoreSectionsPDF (2 MB)Download PDF ToolsExport citationAdd to favoritesGet permissionsTrack citations ShareShare onFacebookTwitterLinkedInWeChat Previous Back to Top Next Download PDF FiguresReferencesRelatedInformation Cited ByPotassium Channels in Drosophila : Historical Breakthroughs, Significance, and Perspectives27 November 2012 | Journal of Neurogenetics, Vol. 26, No. 3-4Contribution of EAG to excitability and potassium currents in Drosophila larval motoneuronsSubhashini Srinivasan, Kimberley Lance, and Richard B. Levine15 May 2012 | Journal of Neurophysiology, Vol. 107, No. 10Eag1 Channels as Potential Cancer Biomarkers10 May 2012 | Sensors, Vol. 12, No. 5Segmental differences in firing properties and potassium currents in Drosophila larval motoneuronsSubhashini Srinivasan, Kimberley Lance, and Richard B. Levine1 March 2012 | Journal of Neurophysiology, Vol. 107, No. 5Pruning of motor neuron branches establishes the DLM innervation pattern inDrosophila1 January 2004 | Journal of Neurobiology, Vol. 60, No. 4Tyramine and octopamine have opposite effects on the locomotion ofDrosophila larvae1 January 2004 | Journal of Neurobiology, Vol. 58, No. 4Acoustic communication in DrosophilaBehavioural Processes, Vol. 64, No. 2Techniques to Dissect Cellular and Subcellular Function in the Drosophila Nervous SystemThe mlenapts RNA Helicase Mutation in Drosophila Results in a Splicing Catastrophe of the para Na + Channel Transcript in a Region of RNA EditingNeuron, Vol. 25, No. 1Auxiliary Hyperkinetic β Subunit of K+Channels: Regulation of Firing Properties and K+ Currents in Drosophila NeuronsWei-Dong Yao, and Chun-Fang Wu1 May 1999 | Journal of Neurophysiology, Vol. 81, No. 5Phenotypic and molecular characterization of croaker, a new mating behavior mutant of Drosophila melanogasterGenes & Genetic Systems, Vol. 70, No. 1Activity-dependent development of the neuromuscular synapse during drosophila embryogenesisNeuron, Vol. 11, No. 4Mutational analysis of Drosophila synaptotagmin demonstrates its essential role in Ca2+-activated neurotransmitter releaseCell, Vol. 74, No. 6Ectopic axonal firing in an epileptic cortical focus is not triggered by thalamocortical volleys during the interictal stageBrain Research, Vol. 576, No. 1The effects of temperature on the physiology of crustacean nerves and musclesJournal of Thermal Biology, Vol. 15, No. 1Molecular characterization of Shaker, a Drosophila gene that encodes a potassium channelCell, Vol. 50, No. 3Drosophila Mutations that Alter Ionic Conduction Disrupt Acquisition and Retention of a Conditioned Odor Avoidance Response11 July 2009 | Journal of Neurogenetics, Vol. 3, No. 4Genes and membrane excitability in DrosophilaTrends in Neurosciences, Vol. 8Ectopic impulse generation in pathological nerve fibresTrends in Neurosciences, Vol. 6 More from this issue > Volume 47Issue 3March 1982Pages 501-14 https://doi.org/10.1152/jn.1982.47.3.501PubMed6279790History Published online 1 March 1982 Published in print 1 March 1982 Metrics

Temperature changes associated with nerve excitation: Detection by using polyvinylidene fluoride film

Summary By using a pyroelectric film made of stretched and poled polyvinylidene fluoride, a small, fast rise in the temperature of the crustacean nerve associated with nerve excitation was detected.

(3)H]Choline uptake and metabolism in nonsynaptic regions of a crustacean sensory nerve.

The posterior stomach nerve (PSN) is a crustacean sensory nerve containing about 60 cholinergic neurons, which are devoid of synaptic interactions. Kinetic analysis shows that the PSN takes up [(3)H]choline by both low-affinity (K(m) = 163 micron) and high-affinity (Na(¿dependent) (K(m) - 1 micron) processes. The capacity of the high-affinity system is only about 1% that of the low-affinity system. The high-affinity system is not tightly coupled to acetylcholine (ACh) synthesis, and it appears that both ACh and phosphorylcholine are formed from an intracellular pool of choline, which is fed by both uptake systems. There are differences in the rates of [(3)H]choline uptake and (3)H metabolite accumulation between regions of the PSN that contain neuronal cell bodies and those that do not. These differences may arise from differences in the relative proportion of neuronal to nonneuronal tissue in each nerve region.

Structure and action of heteronemertine polypeptide toxins: Inactivation of Cerebratulus lacteus toxin B-IV by tyrosine nitration

Reaction of Cerebratulus lacteus toxin B-IV with tetranitromethane in the presence of low concentrations of urea results in essentially complete loss of toxicity as measured by a sensitive quantal bioassay. Amino acid analysis and speetrophotometric studies both indicate the primary effect of reaction to be nitration of a single tyrosine residue per molecule of toxin. The nitrated residue has been identified as tyrosine-9 by automated Edman degradation of the modified protein. Since the secondary structure of toxin B-IV is not detectably altered by nitration, it is concluded that tyrosine-9 is directly involved in the interaction of this polypeptide with its axonal receptor, proposed to be involved in the inactivation of voltage-sensitive Na + channels in crustacean nerves.

Electrophysiological characteristics of crayfish inhibitory.

Parameters of IPSPs and characteristics of inhibitory neuromuscular transmission in the dactylopodite-opener muscle of the crayfish pincer at various rhythms of activity were studied by intracellular recording. The presynaptic conduction nature of high-frequency (pessimal) blockade of the inhibitory system was demonstrated. Transformation of the rhythm of stimulation correlated with a decrease in conduction velocity along the inhibitory axon and (or) its branches. At high frequencies of stimulation the mean quantum composition of IPSPs of the potentiation plateau before the beginning of rhythm transformation was lower than at lower frequencies. No signs of exhaustion of mediator reserves were found in the course of high-frequency activity. It is concluded that the mechanism of secretion of inhibitory mediator is more reliable than the function of conduction of the presynaptic nervous impulse. The possible functional significance of the comparatively low reliability of function of crustacean nerve fibers is discussed.