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Journal of Experimental Zoology. Part... Mar 2011Genome-wide transcriptional changes in development provide important insight into mechanisms underlying growth, differentiation, and patterning. However, such...
Genome-wide transcriptional changes in development provide important insight into mechanisms underlying growth, differentiation, and patterning. However, such large-scale developmental studies have been limited to a few representatives of Ecdysozoans and Chordates. Here, we characterize transcriptomes of embryonic, larval, and metamorphic development in the marine mollusc Aplysia californica and reveal novel molecular components associated with life history transitions. Specifically, we identify more than 20 signal peptides, putative hormones, and transcription factors in association with early development and metamorphic stages-many of which seem to be evolutionarily conserved elements of signal transduction pathways. We also characterize genes related to biomineralization-a critical process of molluscan development. In summary, our experiment provides the first large-scale survey of gene expression in mollusc development, and complements previous studies on the regulatory mechanisms underlying body plan patterning and the formation of larval and juvenile structures. This study serves as a resource for further functional annotation of transcripts and genes in Aplysia, specifically and molluscs in general. A comparison of the Aplysia developmental transcriptome with similar studies in the zebra fish Danio rerio, the fruit fly Drosophila melanogaster, the nematode Caenorhabditis elegans, and other studies on molluscs suggests an overall highly divergent pattern of gene regulatory mechanisms that are likely a consequence of the different developmental modes of these organisms.
Topics: Animals; Aplysia; Body Patterning; Cluster Analysis; DNA; Gene Expression Profiling; Gene Expression Regulation, Developmental; Oligonucleotide Array Sequence Analysis; Reproducibility of Results; Reverse Transcriptase Polymerase Chain Reaction; Signal Transduction; Transcription, Genetic
PubMed: 21328528
DOI: 10.1002/jez.b.21383 -
Neuron Feb 2006Synapse formation is initiated by cell-cell contact between appropriate pre- and postsynaptic cells and is followed by recruitment of protein complexes in both pre- and... (Review)
Review
Synapse formation is initiated by cell-cell contact between appropriate pre- and postsynaptic cells and is followed by recruitment of protein complexes in both pre- and postsynaptic compartments. In this issue of Neuron, Lyles et al. show that in cultured Aplysia neurons, clustering of an mRNA at nascent synapses is not only induced by the recognition between synaptic partners, but is also required for further synaptic development and maintenance.
Topics: Animals; Aplysia; Cells, Cultured; Models, Biological; Neurons; Protein Biosynthesis; Synapses
PubMed: 16446134
DOI: 10.1016/j.neuron.2006.01.011 -
Brain, Behavior and Evolution 2009The motor systems that generate feeding-related behaviors of gastropod mollusks provide exceptional opportunities for increasing our understanding of neural homologies... (Review)
Review
The motor systems that generate feeding-related behaviors of gastropod mollusks provide exceptional opportunities for increasing our understanding of neural homologies and the evolution of neural networks. This report examines the neural control of feeding in Helisoma trivolvis, a pulmonate snail that ingests food by rasping or scraping material from the substrate, and Aplysia californica, an opisthobranch sea slug that feeds by using a grasping or seizing motion. Two classes of neurons that are present in the buccal ganglia of both species are considered: (1) clusters of peptidergic mechanoafferent cells that transmit sensory information from the tongue-like radula/odontophore complex to the central motor circuit; and (2) sets of octopamine-immunoreactive interneurons that are intrinsic to the feeding network. We review evidence that suggests homology of these cell types and propose that their roles have been largely conserved in the control of food-scraping and food-grasping consummatory behaviors. We also consider significant differences in the feeding systems of Aplysia and Helisoma that are associated with the existence of radular closure in Aplysia, an action that does not occur in Helisoma. It is hypothesized that a major adaptation in the innervation patterns of analogous, possibly homologous muscles could distinguish the food-scraping versus food-grasping species. It appears that although core CPG elements have been largely conserved in this system, the neuromuscular elements that they regulate have been more evolutionarily labile.
Topics: Animals; Aplysia; Biological Evolution; Eating; Feeding Behavior; Lymnaea; Neurons; Species Specificity
PubMed: 20029185
DOI: 10.1159/000258668 -
Neuron Mar 1997
Review
Topics: Animals; Aplysia; Gene Expression Regulation; Humans; Long-Term Potentiation; Memory; Models, Neurological; Nerve Tissue Proteins; RNA, Messenger; Serotonin; Synapses
PubMed: 9115727
DOI: 10.1016/s0896-6273(00)81234-9 -
Molecular Brain Jun 2008Whereas the induction of short-term memory involves only covalent modifications of constitutively expressed preexisting proteins, the formation of long-term memory... (Review)
Review
Whereas the induction of short-term memory involves only covalent modifications of constitutively expressed preexisting proteins, the formation of long-term memory requires gene expression, new RNA, and new protein synthesis. On the cellular level, transcriptional regulation is thought to be the starting point for a series of molecular steps necessary for both the initiation and maintenance of long-term synaptic facilitation (LTF). The core molecular features of transcriptional regulation involved in the long-term process are evolutionally conserved in Aplysia, Drosophila, and mouse, and indicate that gene regulation by the cyclic AMP response element binding protein (CREB) acting in conjunction with different combinations of transcriptional factors is critical for the expression of many forms of long-term memory. In the marine snail Aplysia, the molecular mechanisms that underlie the storage of long-term memory have been extensively studied in the monosynaptic connections between identified sensory neuron and motor neurons of the gill-withdrawal reflex. One tail shock or one pulse of serotonin (5-HT), a modulatory transmitter released by tail shocks, produces a transient facilitation mediated by the cAMP-dependent protein kinase leading to covalent modifications in the sensory neurons that results in an enhancement of transmitter release and a strengthening of synaptic connections lasting minutes. By contrast, repeated pulses of 5-hydroxytryptamine (5-HT) induce a transcription- and translation-dependent long-term facilitation (LTF) lasting more than 24 h and trigger the activation of a family of transcription factors in the presynaptic sensory neurons including ApCREB1, ApCREB2 and ApC/EBP. In addition, we have recently identified novel transcription factors that modulate the expression of ApC/EBP and also are critically involved in LTF. In this review, we examine the roles of these transcription factors during consolidation of LTF induced by different stimulation paradigms.
Topics: Animals; Aplysia; Aquatic Organisms; Gene Expression Regulation; Memory, Long-Term; Seawater; Snails; Transcription, Genetic
PubMed: 18803855
DOI: 10.1186/1756-6606-1-3 -
Cellular and Molecular Life Sciences :... May 2006Recent research in a variety of systems indicates that memory formation can involve the activation of a wide range of molecular cascades. In assessing this recent work... (Review)
Review
Recent research in a variety of systems indicates that memory formation can involve the activation of a wide range of molecular cascades. In assessing this recent work it is clear that no single cascade is uniquely important for all forms of memory, nor is a single form of memory uniquely dependent on a single cascade. Rather, it appears that molecular networks are differentially engaged in the induction of various forms of memory. Despite this highly interactive array of possible cascades, specific 'molecular nodes' have emerged as critical regulatory points in memory formation. Functionally, these nodes can operate in two sequential steps, beginning with a convergence of inputs which coordinately influence the activation state of the node, in which the nature of stimulation determines the dynamics of nodal activity, followed by a divergence of substrate selection, in which the node serves as a gateway that activates specific downstream effectors. Finally, specific nodes can be differentially engaged (i.e. have different 'weights') depending upon the nature and pattern of the activating stimulus. The marine mollusk Aplysia has proven useful for a molecular analysis of memory formation. We will use this system to highlight some of the molecular strategies employed by the nervous system in the formation of memory for sensitization, and we will focus on extracellular signal-related kinase as a candidate node integral to these processes.
Topics: Animals; Aplysia; Enzyme Activation; Extracellular Signal-Regulated MAP Kinases; Gene Expression Regulation; Memory; Models, Biological; Neuronal Plasticity; Protein Biosynthesis; Serotonin; Signal Transduction
PubMed: 16596335
DOI: 10.1007/s00018-006-6022-x -
The Journal of Neuroscience : the... Apr 2003Structural changes at synapses are associated with long-term facilitation (LTF) of synaptic transmission between sensory and motor neurons in Aplysia. We have cloned a...
Identification and characterization of Aplysia adducin, an Aplysia cytoskeletal protein homologous to mammalian adducins: increased phosphorylation at a protein kinase C consensus site during long-term synaptic facilitation.
Structural changes at synapses are associated with long-term facilitation (LTF) of synaptic transmission between sensory and motor neurons in Aplysia. We have cloned a cDNA encoding Aplysia adducin (ApADD), the Aplysia homolog of mammalian adducins that are regulatory components of the membrane cytoskeleton. ApADD is recovered in the particulate fraction of nervous system extracts and is localized predominantly in the submembraneous region of Aplysia neurons. ApADD is phosphorylated in vitro by protein kinase C (PKC) at a site homologous to the in vivo PKC phosphorylation site in mammalian adducins. Phosphorylation of ApADD at this site is also detected in vivo in the intact Aplysia nervous system and is increased 18 hr after serotonin-induced LTF. In contrast, there is no change in phosphorylation during short-term facilitation or 1 hr after initial LTF induction. Thus, ApADD is modulated specifically with later phases of LTF and provides an attractive candidate protein that contributes to structural changes accompanying long-lasting synaptic alteration.
Topics: Amino Acid Sequence; Animals; Aplysia; Calmodulin-Binding Proteins; Cloning, Molecular; Consensus Sequence; Cytoskeletal Proteins; Humans; Kinetics; Mammals; Mice; Models, Biological; Molecular Sequence Data; Motor Neurons; Nervous System; Neuronal Plasticity; Neurons; Neurons, Afferent; Phosphorylation; Protein Kinase C; Protein Structure, Tertiary; Sequence Homology, Amino Acid; Serotonin; Synaptic Transmission
PubMed: 12684453
DOI: 10.1523/JNEUROSCI.23-07-02675.2003 -
Nature Jan 2017The Ca-activated K channel, Slo1, has an unusually large conductance and contains a voltage sensor and multiple chemical sensors. Dual activation by membrane voltage and...
The Ca-activated K channel, Slo1, has an unusually large conductance and contains a voltage sensor and multiple chemical sensors. Dual activation by membrane voltage and Ca renders Slo1 central to processes that couple electrical signalling to Ca-mediated events such as muscle contraction and neuronal excitability. Here we present the cryo-electron microscopy structure of a full-length Slo1 channel from Aplysia californica in the presence of Ca and Mg at a resolution of 3.5 Å. The channel adopts an open conformation. Its voltage-sensor domain adopts a non-domain-swapped attachment to the pore and contacts the cytoplasmic Ca-binding domain from a neighbouring subunit. Unique structural features of the Slo1 voltage sensor suggest that it undergoes different conformational changes than other known voltage sensors. The structure reveals the molecular details of three distinct divalent cation-binding sites identified through electrophysiological studies of mutant Slo1 channels.
Topics: Allosteric Regulation; Amino Acid Sequence; Animals; Aplysia; Binding Sites; Calcium; Cations, Divalent; Cryoelectron Microscopy; Cytoplasm; Electrophysiological Phenomena; Large-Conductance Calcium-Activated Potassium Channels; Lipid Bilayers; Magnesium; Models, Molecular; Protein Domains; Protein Subunits
PubMed: 27974795
DOI: 10.1038/nature20608 -
Journal of Cell Science Apr 2020Previously, we have shown that bulk microtubule (MT) movement correlates with neurite elongation, and blocking either dynein activity or MT assembly inhibits both...
Previously, we have shown that bulk microtubule (MT) movement correlates with neurite elongation, and blocking either dynein activity or MT assembly inhibits both processes. However, whether the contributions of MT dynamics and dynein activity to neurite elongation are separate or interdependent is unclear. Here, we investigated the underlying mechanism by testing the roles of dynein and MT assembly in neurite elongation of and chick neurites using time-lapse imaging, fluorescent speckle microscopy, super-resolution imaging and biophysical analysis. Pharmacologically inhibiting either dynein activity or MT assembly reduced neurite elongation rates as well as bulk and individual MT anterograde translocation. Simultaneously suppressing both processes did not have additive effects, suggesting a shared mechanism of action. Single-molecule switching nanoscopy revealed that inhibition of MT assembly decreased the association of dynein with MTs. Finally, inhibiting MT assembly prevented the rise in tension induced by dynein inhibition. Taken together, our results suggest that MT assembly is required for dynein-driven MT translocation and neurite outgrowth.
Topics: Animals; Aplysia; Dyneins; Microtubules; Neurites; Neuronal Outgrowth; Neurons
PubMed: 32332091
DOI: 10.1242/jcs.232983 -
Transcriptome analysis and identification of regulators for long-term plasticity in Aplysia kurodai.Proceedings of the National Academy of... Nov 2008The marine mollusk Aplysia is a useful model organism for studying the cellular bases of behavior and plasticity. However, molecular studies of Aplysia have been limited...
The marine mollusk Aplysia is a useful model organism for studying the cellular bases of behavior and plasticity. However, molecular studies of Aplysia have been limited by the lack of genomic information. Recently, a large scale characterization of neuronal transcripts was performed in A. californica. Here, we report the analysis of a parallel set of neuronal transcripts from a closely related species A. kurodai found in the northwestern Pacific. We collected 4,859 nonredundant sequences from the nervous system tissue of A. kurodai. By performing microarray and real-time PCR analyses, we found that ApC/EBP, matrilin, antistasin, and eIF3e clones were significantly up-regulated and a BAT1 homologous clone was significantly down-regulated by 5-HT treatment. Among these, we further demonstrated that the Ap-eIF3e plays a key role in 5-HT-induced long-term facilitation (LTF) as a positive regulator.
Topics: Animals; Aplysia; Base Sequence; DNA Primers; Expressed Sequence Tags; Long-Term Potentiation; Neuronal Plasticity; Polymerase Chain Reaction; RNA, Messenger; Serotonin
PubMed: 19017802
DOI: 10.1073/pnas.0808893105