The Experts below are selected from a list of 300 Experts worldwide ranked by ideXlab platform
Paul S. Katz - One of the best experts on this subject based on the ideXlab platform.
-
The Tritonia Swim Central Pattern Generator
Handbook of Brain Microcircuits, 2017Co-Authors: Paul S. KatzAbstract:Tritonia diomedea is a sea slug that escapes from predatory starfish by rhythmically flexing its entire body in the dorsal and ventral directions. This escape swim behavior is produced by a central pattern generator (CPG), without needing sensory feedback. There are several features of the neural basis for this response that make it of particular interest for neuroscientists. One is that the CPG is a network oscillator; bursting arises as an emergent property of the neurons and their connectivity. Another interesting feature is that the CPG contains state-dependent, intrinsic neuromodulation: one of the CPG neurons uses the neurotransmitter serotonin (5-HT) to modulate the strength of synapses made by the other CPG neurons under certain conditions. This CPG seems to have evolved from a nonoscillatory network. Finally, there are novel mechanisms for plasticity during learning and in response to injury.
-
Deep mRNA Sequencing of the Tritonia diomedea Brain Transcriptome Provides Access to Gene Homologues for Neuronal Excitability, Synaptic Transmission and Peptidergic Signalling
PloS one, 2015Co-Authors: Adriano Senatore, Neranjan Edirisinghe, Paul S. KatzAbstract:Background The sea slug Tritonia diomedea (Mollusca, Gastropoda, Nudibranchia), has a simple and highly accessible nervous system, making it useful for studying neuronal and synaptic mechanisms underlying behavior. Although many important contributions have been made using Tritonia, until now, a lack of genetic information has impeded exploration at the molecular level.
-
Combined graphs of gene ontology mappings for Tritonia TSA unigene sequences.
2015Co-Authors: Adriano Senatore, Neranjan Edirisinghe, Paul S. KatzAbstract:A) Number of unigene Trinity contigs (BHPC against Swiss-Prot; bottom axis) having GO-terms for molecular function (i.e. multi-level GO terms filtered by number of sequences). The most prominent GO assignments for the Tritonia TSA include binding activity, such as nucleotide and DNA binding, and receptor activity. B) Number unigene contigs with multi-level GO terms associated with biological function. The red bars illustrate that a significant number of genes from the Tritonia TSA are mapped with terms for cell proliferation and differentiation (cell cycle = 460; cellular proliferation = 214; cellular differentiation = 494), which is unexpected given that most neurons in the adult CNS are expected to be non-proliferative and terminally differentiated.
-
Phylogenetic analyses of Tritonia genes involved in propagating electrical signals.
2015Co-Authors: Adriano Senatore, Neranjan Edirisinghe, Paul S. KatzAbstract:A) Depiction of three gene products with a central involvement in neuronal electrical signaling. The Na+/K+ ATPase pump actively transports three Na+ ions out of the cell for every 2 K+ ions pumped in, generating a charge differential across the cell membrane stored as electrical potential energy (resting membrane potential; RMP). The inside-negative RMP is a pre-requisite action potential propagation in neurons, where a propagating wave of depolarization mediated by Na+ influx through voltage-gated sodium (Nav) channels is countered by voltage-gated potassium (Kv) channels that restore membrane polarization. B) A maximum likelihood phylogenetic tree based on MUSCLE alignment of Na+/K+ ATPase homologues from various species: Tritonia diomedea (extracted from CNS TSA), Melibe leonina (also a nudibranch; extracted from unpublished CNS TSA), Aplysia californica (GenBank accession no. XP_005093050.1), Lymnaea stagnalis (accession no. FX180758.1), Drosophila melanogaster (accession no. NP_996247.1), Caenhorhabditis elegans (accession no. NP_506269.1), Homo sapiens (accession no. NP_689509.1) and Nematostella vectensis (sequence ID NVE24413 from unpublished TSA [19]). C) Phylogenetic analysis of neuronal voltage-gated sodium (Nav1) channel homologues. GenBank accession numbers: Lymnaea FX180203.1; Aplysia AAC47457.1; Drosophila NP_001188603.1; H.sapiens BAC21101.1; and Nematostella (merge between TSA NVE7195 [19] and GenBank accession XP_001627761.1). D) Phylogeny for rapidly activating A-type potassium (Kv) channels. GenBank accession numbers: Lymnaea FX185418.1; Aplysia XP_005091742.1; Drosophila NP_001097646.1; C.elegans NP_500975.2; H.sapiens AAD22053.1; and Nematostella (TSA NVE15334 [19]). E) Depiction of the expected topology for the Tritonia Nav1 channel, with 4 repeat domains (I to IV) each containing 6 transmembrane helices (S1 to S6, numbered left to right in each domain). The S4 helices are packed with alternating positively charged Lysine (K) or arginine (R) residues for voltage sensing. The pore-loops between S5 and S6 each project one of four key selectivity filter amino acids into the channel pore to define Na+ selectivity: aspartate (D); glutamate (E); Lysine (K); and alanine (A). The expected topology of Tritonia Nav1 is supported by hydrophobic peaks on a Kyte-Doolittle hydrophobicity plot (window size of 17; y-axis is the hydrophobicity score), that likely fold into transmembrane alpha-helices. F) Alignment of the pore-loop selectivity filter regions, and the Domain III-IV intracellular loop that houses the fast inactivation gate for Nav1 channels. The black arrows represent regions in the invertebrate channels that have diverged from vertebrate channels in positions known to affect TTX sensitivity [49].
-
Reciprocal BLASTn comparisons of the Tritonia TSA and Tritonia EST sequences.
2015Co-Authors: Adriano Senatore, Neranjan Edirisinghe, Paul S. KatzAbstract:Reciprocal BLASTn comparisons of the Tritonia TSA and Tritonia EST sequences.
William N Frost - One of the best experts on this subject based on the ideXlab platform.
-
serial section atlas of the Tritonia pedal ganglion
Journal of Neurophysiology, 2018Co-Authors: Christopher Brandon, Jean Wang, Evan S. Hill, Matthew Cale Britton, David Fan, Andrew R Ferrier, Adrian Perez, Nengding Wang, William N FrostAbstract:Because of the large size and relatively low numbers of their neurons, gastropod mollusks are widely used for investigations of the neural basis of behavior. Most studies, however, focus on the neu...
-
Dishabituation of the Tritonia Escape Swim
2016Co-Authors: Donna L. Mongeluzi, William N FrostAbstract:When repeatedly elicited, the oscillatory escape swim of the marine mollusc Tritonia diomedea undergoes habituation of the number of cycles per swim. Although similar in most respects to habituation observed in vertebrates and other invertebrates, one key feature, dishabituation, has been surprisingly difficult to demonstrate. Here we evaluate the hypothesis that this is due to interference from short-term sensitization, which is manifested as a reduction in swim onset latency, that occurs simultaneously during habituation training. Robust dishabituation was obtained using a multisession habituation protocol designed to allow this sensitization to dissipate before the dishabituatory stimulus was applied. These results extend the similarity of habituation in Tritonia to that described in other species, strengthening the usefulness of this preparation as a model system for studies of the cellular basis of habituation
-
Axonal Conduction Block as a Novel Mechanism of Prepulse Inhibition
The Journal of Neuroscience, 2012Co-Authors: Evgenia V. Megalou, Jean Wang, William N FrostAbstract:In prepulse inhibition (PPI), the startle response to a strong, unexpected stimulus is diminished if shortly preceded by the onset of a different stimulus. Because deficits in this inhibitory gating process are a hallmark feature of schizophrenia and certain other psychiatric disorders, the mechanisms underlying PPI are of significant interest. We previously used the invertebrate model system Tritonia diomedea to identify the first cellular mechanism for PPI—presynaptic inhibition of transmitter release from the afferent neurons (S-cells) mediating the startle response. Here, we report the involvement of a second, more powerful PPI mechanism in Tritonia : prepulse-elicited conduction block of action potentials traveling in the startle pathway caused by identified inhibitory interneurons activated by the prepulse. This example of axo-axonic conduction block—neurons in one pathway inhibiting the propagation of action potentials in another—represents a novel and potent mechanism of sensory gating in prepulse inhibition.
-
Variable neuronal participation in stereotypic motor programs.
PloS one, 2012Co-Authors: Evan S. Hill, Jean Wang, Sunil K. Vasireddi, Angela M. Bruno, William N FrostAbstract:To what extent are motor networks underlying rhythmic behaviors rigidly hard-wired versus fluid and dynamic entities? Do the members of motor networks change from moment-to-moment or from motor program episode-to-episode? These are questions that can only be addressed in systems where it is possible to monitor the spiking activity of networks of neurons during the production of motor programs. We used large-scale voltage-sensitive dye (VSD) imaging followed by Independent Component Analysis spike-sorting to examine the extent to which the neuronal network underlying the escape swim behavior of Tritonia diomedea is hard-wired versus fluid from a moment-to-moment perspective. We found that while most neurons were dedicated to the swim network, a small but significant proportion of neurons participated in a surprisingly variable manner. These neurons joined the swim motor program late, left early, burst only on some cycles or skipped cycles of the motor program. We confirmed that this variable neuronal participation was not due to effects of the VSD by finding such neurons with intracellular recording in dye-free saline. Further, these neurons markedly varied their level of participation in the network from swim episode-to-episode. The generality of such unreliably bursting neurons was confirmed by their presence in the rhythmic escape networks of two other molluscan species, Tritonia festiva and Aplysia californica. Our observations support a view that neuronal networks, even those underlying rhythmic and stereotyped motor programs, may be more variable in structure than widely appreciated.
-
Evidence that the swim afferent neurons of Tritonia diomedea are glutamatergic.
The Biological bulletin, 2009Co-Authors: E. V. Megalou, C. J. Brandon, William N FrostAbstract:The escape swim response of the marine mollusc Tritonia diomedea is a well-established model system for studies of the neural basis of behavior. Although the swim neural network is reasonably well understood, little is known about the transmitters used by its constituent neurons. In the present study, we provide immunocytochemical and electrophysiological evidence that the S-cells, the afferent neurons that detect aversive skin stimuli and in turn trigger Tritonia's escape swim response, use glutamate as their transmitter. First, immunolabeling revealed that S-cell somata contain elevated levels of glutamate compared to most other neurons in the Tritonia brain, consistent with findings from glutamatergic neurons in many species. Second, pressure-applied puffs of glutamate produced the same excitatory response in the target neurons of the S-cells as the naturally released S-cell transmitter itself. Third, the glutamate receptor antagonist CNQX completely blocked S-cell synaptic connections. These findings ...
Adriano Senatore - One of the best experts on this subject based on the ideXlab platform.
-
Deep mRNA Sequencing of the Tritonia diomedea Brain Transcriptome Provides Access to Gene Homologues for Neuronal Excitability, Synaptic Transmission and Peptidergic Signalling
PloS one, 2015Co-Authors: Adriano Senatore, Neranjan Edirisinghe, Paul S. KatzAbstract:Background The sea slug Tritonia diomedea (Mollusca, Gastropoda, Nudibranchia), has a simple and highly accessible nervous system, making it useful for studying neuronal and synaptic mechanisms underlying behavior. Although many important contributions have been made using Tritonia, until now, a lack of genetic information has impeded exploration at the molecular level.
-
Reciprocal BLASTn comparisons of the Tritonia TSA and Tritonia EST sequences.
2015Co-Authors: Adriano Senatore, Neranjan Edirisinghe, Paul S. KatzAbstract:Reciprocal BLASTn comparisons of the Tritonia TSA and Tritonia EST sequences.
-
Deep mRNA Sequencing of the Tritonia diomedea Brain Transcriptome Provides Access to Gene Homologues for Neuronal Excitability, Synaptic Transmission and Peptidergic Signalling
2015Co-Authors: Adriano Senatore, Neranjan Edirisinghe, Paul S. KatzAbstract:BackgroundThe sea slug Tritonia diomedea (Mollusca, Gastropoda, Nudibranchia), has a simple and highly accessible nervous system, making it useful for studying neuronal and synaptic mechanisms underlying behavior. Although many important contributions have been made using Tritonia, until now, a lack of genetic information has impeded exploration at the molecular level.ResultsWe performed Illumina sequencing of central nervous system mRNAs from Tritonia, generating 133.1 million 100 base pair, paired-end reads. De novo reconstruction of the RNA-Seq data yielded a total of 185,546 contigs, which partitioned into 123,154 non-redundant gene clusters (unigenes). BLAST comparison with RefSeq and Swiss-Prot protein databases, as well as mRNA data from other invertebrates (gastropod molluscs: Aplysia californica, Lymnaea stagnalis and Biomphalaria glabrata; cnidarian: Nematostella vectensis) revealed that up to 76,292 unigenes in the Tritonia transcriptome have putative homologues in other databases, 18,246 of which are below a more stringent E-value cut-off of 1x10-6. In silico prediction of secreted proteins from the Tritonia transcriptome shotgun assembly (TSA) produced a database of 579 unique sequences of secreted proteins, which also exhibited markedly higher expression levels compared to other genes in the TSA.ConclusionsOur efforts greatly expand the availability of gene sequences available for Tritonia diomedea. We were able to extract full length protein sequences for most queried genes, including those involved in electrical excitability, synaptic vesicle release and neurotransmission, thus confirming that the transcriptome will serve as a useful tool for probing the molecular correlates of behavior in this species. We also generated a neurosecretome database that will serve as a useful tool for probing peptidergic signalling systems in the Tritonia brain.
-
Absence of a signal peptide of the Tritonia FMRFamide homologue due to incomplete assembly.
2015Co-Authors: Adriano Senatore, Neranjan Edirisinghe, Paul S. KatzAbstract:A MUSCLE protein alignment of FMRFamide homologues from Tritonia, fellow Nudibranch Melibe leonina, and fellow gastropods Aplysia californica (UniProt accession no. P08021) and Lymnaea stagnalis (UniProt accession no. P08021) reveals the absence of a signal peptide at the Tritonia FMRFamide N-terminus caused by incomplete assembly of this particular gene transcript. The Aplysia pre-pro-peptide had 29 FMRFamide repeats compared to 13 in Lymnaea, 7 in Tritonia, and 6 in Melibe. Amino acids corresponding to SignalP-predicted signal peptides are shown with a blue background, arginine (R) and lysine (K) residues corresponding to putative convertase cleavage sites are depicted with a red background, and potential glycines that are converted to amides have an orange background.
-
Metrics for the Tritonia TSA and predicted peptides.
2015Co-Authors: Adriano Senatore, Neranjan Edirisinghe, Paul S. KatzAbstract:Abbreviations: amino acids (aa), nucleotides (nt), longest contig per component (LCPC), open reading frames (ORFs).Metrics for the Tritonia TSA and predicted peptides.
Rhanor Gillette - One of the best experts on this subject based on the ideXlab platform.
-
Serotonin Immunoreactivity in the Central Nervous System of the Marine Molluscs Pleurobranchaea californica and Tritonia diomedea
The Journal of comparative neurology, 1998Co-Authors: Leland C. Sudlow, Jian Jing, Leonid L. Moroz, Rhanor GilletteAbstract:The central nervous systems of the marine molluscs Pleurobranchaea californica (Opisthobranchia: Notaspidea) and Tritonia diomedea (Opisthobranchia: Nudibranchia) were examined for serotonin-immunoreactive (5-HT-IR) neurons and processes. Bilaterally paired clusters of 5-HT-IR neuron somata were distributed similarly in ganglia of the two species. In the cerebropleural ganglion complex, these were the metacerebral giant neurons (both species), a dorsal anterior cluster (Pleurobranchaea only), a dorsal medial cluster including identified neurons of the escape swimming network (both species), and a dorsal lateral cluster in the cerebropleural ganglion (Pleurobranchaea only). A ventral anterior cluster (both species) adjoined the metacerebral giant somata at the anterior ganglion edge. Pedal ganglia had the greatest number of 5-HT-IR somata, the majority located near the roots of the pedal commissure in both species. Most 5-HT-IR neurons were on the dorsal surface of the pedal ganglia in Pleurobranchaea and were ventral in Tritonia. Neither the buccal ganglion of both species nor the visceral ganglion of Pleurobranchaea had 5-HT-IR somata. A few asymmetrical 5-HT-IR somata were found in cerebropleural and pedal ganglia in both species, always on the left side. The clustering of 5-HT-IR neurons, their diverse axon pathways, and the known physiologic properties of their identified members are consistent with a loosely organized arousal system of serotonergic neurons whose components can be generally or differentially active in expression of diverse behaviors. J. Comp. Neurol. 395:466‐480, 1998. r 1998 Wiley-Liss, Inc. Indexing terms: serotonin; immunohistochemistry; Mollusca; Aplysia; Lymnaea
-
Serotonin-immunoreactivity in peripheral tissues of the opisthobranch molluscs Pleurobranchaea californica and Tritonia diomedea.
The Journal of comparative neurology, 1997Co-Authors: Leonid L. Moroz, Leland C. Sudlow, Jian Jing, Rhanor GilletteAbstract:The distribution of serotonin (5-HT)-immunoreactive elements in peripheral organs of the sea-slugs Pleurobranchaea californica and Tritonia diomedea was studied in cryostat sections. ForPleurobranchaea, 5-HT-immunoreactive (5-HT-IR) neuron cell bodies were found only in the central nervous system (CNS); 5-HT-IR cell bodies were not observed in foot, tentacles, rhinophores, oral veil, mouth, buccal mass, esophagus, gills, salivary glands, skin, reproductive system, and acidic glands, nor in peripheral tentacle and rhinophore ganglia. However, 5-HT-IR neuronal processes were widely distributed in these structures and the patterns of 5-HT-IR elements were characteristic for each particular peripheral tissue. 5-HT-IR elements were most dense in the sole of the foot and the reproductive system, followed by rhinophores, tentacles, oral veil, mouth, buccal mass, and esophagus. The sensory epithelium of rhinophores, tentacles, and mouth showed a highly structured glomerular organization of 5-HT-IR fibers, suggesting a role for 5-HT in sensory signaling. A much lower density of 5-HT-IR innervation was observed in gills, skin, salivary, and acidic glands. 5-HT-IR was observed in neuropil of tentacle and rhinophore ganglia with many transverse 5-HT-IR axons running to peripheral sensory areas. The distribution of 5-HT-IR elements in Tritonia was similar to that of Pleurobranchaea. A significant suggestion of the data is that central serotonergic neurons may modulate afferent pathways from sensory epithelia at the periphery. J. Comp. Neurol. 382:176‐188, 1997. r 1997 Wiley-Liss, Inc.
Neranjan Edirisinghe - One of the best experts on this subject based on the ideXlab platform.
-
Deep mRNA Sequencing of the Tritonia diomedea Brain Transcriptome Provides Access to Gene Homologues for Neuronal Excitability, Synaptic Transmission and Peptidergic Signalling
PloS one, 2015Co-Authors: Adriano Senatore, Neranjan Edirisinghe, Paul S. KatzAbstract:Background The sea slug Tritonia diomedea (Mollusca, Gastropoda, Nudibranchia), has a simple and highly accessible nervous system, making it useful for studying neuronal and synaptic mechanisms underlying behavior. Although many important contributions have been made using Tritonia, until now, a lack of genetic information has impeded exploration at the molecular level.
-
Reciprocal BLASTn comparisons of the Tritonia TSA and Tritonia EST sequences.
2015Co-Authors: Adriano Senatore, Neranjan Edirisinghe, Paul S. KatzAbstract:Reciprocal BLASTn comparisons of the Tritonia TSA and Tritonia EST sequences.
-
Deep mRNA Sequencing of the Tritonia diomedea Brain Transcriptome Provides Access to Gene Homologues for Neuronal Excitability, Synaptic Transmission and Peptidergic Signalling
2015Co-Authors: Adriano Senatore, Neranjan Edirisinghe, Paul S. KatzAbstract:BackgroundThe sea slug Tritonia diomedea (Mollusca, Gastropoda, Nudibranchia), has a simple and highly accessible nervous system, making it useful for studying neuronal and synaptic mechanisms underlying behavior. Although many important contributions have been made using Tritonia, until now, a lack of genetic information has impeded exploration at the molecular level.ResultsWe performed Illumina sequencing of central nervous system mRNAs from Tritonia, generating 133.1 million 100 base pair, paired-end reads. De novo reconstruction of the RNA-Seq data yielded a total of 185,546 contigs, which partitioned into 123,154 non-redundant gene clusters (unigenes). BLAST comparison with RefSeq and Swiss-Prot protein databases, as well as mRNA data from other invertebrates (gastropod molluscs: Aplysia californica, Lymnaea stagnalis and Biomphalaria glabrata; cnidarian: Nematostella vectensis) revealed that up to 76,292 unigenes in the Tritonia transcriptome have putative homologues in other databases, 18,246 of which are below a more stringent E-value cut-off of 1x10-6. In silico prediction of secreted proteins from the Tritonia transcriptome shotgun assembly (TSA) produced a database of 579 unique sequences of secreted proteins, which also exhibited markedly higher expression levels compared to other genes in the TSA.ConclusionsOur efforts greatly expand the availability of gene sequences available for Tritonia diomedea. We were able to extract full length protein sequences for most queried genes, including those involved in electrical excitability, synaptic vesicle release and neurotransmission, thus confirming that the transcriptome will serve as a useful tool for probing the molecular correlates of behavior in this species. We also generated a neurosecretome database that will serve as a useful tool for probing peptidergic signalling systems in the Tritonia brain.
-
Absence of a signal peptide of the Tritonia FMRFamide homologue due to incomplete assembly.
2015Co-Authors: Adriano Senatore, Neranjan Edirisinghe, Paul S. KatzAbstract:A MUSCLE protein alignment of FMRFamide homologues from Tritonia, fellow Nudibranch Melibe leonina, and fellow gastropods Aplysia californica (UniProt accession no. P08021) and Lymnaea stagnalis (UniProt accession no. P08021) reveals the absence of a signal peptide at the Tritonia FMRFamide N-terminus caused by incomplete assembly of this particular gene transcript. The Aplysia pre-pro-peptide had 29 FMRFamide repeats compared to 13 in Lymnaea, 7 in Tritonia, and 6 in Melibe. Amino acids corresponding to SignalP-predicted signal peptides are shown with a blue background, arginine (R) and lysine (K) residues corresponding to putative convertase cleavage sites are depicted with a red background, and potential glycines that are converted to amides have an orange background.
-
Metrics for the Tritonia TSA and predicted peptides.
2015Co-Authors: Adriano Senatore, Neranjan Edirisinghe, Paul S. KatzAbstract:Abbreviations: amino acids (aa), nucleotides (nt), longest contig per component (LCPC), open reading frames (ORFs).Metrics for the Tritonia TSA and predicted peptides.
