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The Journal of Biological Chemistry Jun 2004Mate attraction in Aplysia involves a long-distance water-borne signal (attractin) that is released during egg laying. Other pheromones are predicted to be released...
Mate attraction in Aplysia involves a long-distance water-borne signal (attractin) that is released during egg laying. Other pheromones are predicted to be released during egg laying that act in concert with albumen gland attractin to stimulate attraction, but their identities are unknown. To identify other candidate water-borne pheromones, we employed differential library screening of an albumen gland cDNA library, Northern blot analysis, purification, characterization, cloning, and expression of albumen gland proteins, matrix-assisted laser desorption ionization mass spectrometry, pheromone secretion assays, behavioral bioassays, immunolocalization studies, and comparative genomics. Four genes, Alb-23, Alb-24, Alb-69, and Alb-172, were highly expressed in Aplysia californica albumen glands and encoded novel proteins. The products of the Alb-24 ("enticin") and Alb-172 ("temptin") precursors were soluble and highly abundant in albumen gland extracts, whereas Alb-23 and Alb-69 were membrane-associated proteins. A comparative analysis showed that the predicted Aplysia brasiliana enticin and temptin proteins were 90 and 91% identical, respectively, to their A. californica homologs. T-maze attraction bioassay studies have previously demonstrated that egg cordons alone are attractive to Aplysia but that attractin alone is not. In the present study, however, the combination of attractin, enticin, and temptin was found to be significantly attractive to potential mates and doubled the number of animals attracted to this stimulus compared with control animals. The combined data strongly suggest that enticin and temptin are novel candidate water-borne protein pheromones that act in concert with attractin to attract Aplysia to form and maintain egglaying and mating aggregations.
Topics: Amino Acid Sequence; Animals; Aplysia; Cloning, Molecular; Fluorescent Antibody Technique; Gene Library; Glycoproteins; Molecular Sequence Data; Oviposition; Pheromones; Recombinant Proteins; Sexual Behavior, Animal
PubMed: 15054104
DOI: 10.1074/jbc.M313585200 -
Behavioural Brain Research Feb 2022Although prolonged food deprivation is known to cause memory deficits, the underlying mechanisms are only partially understood. In this study, we began to investigate...
Although prolonged food deprivation is known to cause memory deficits, the underlying mechanisms are only partially understood. In this study, we began to investigate the cellular substrates of food deprivation-induced memory impairments in the invertebrate Aplysia. Following a single trial of noxious stimuli, Aplysia concurrently express short-term sensitization (an elementary form of learning in which withdrawal reflexes are enhanced) and short-term feeding suppression for at least 15 min. Cellular correlates of sensitization and feeding suppression include increased excitability of the tail sensory neurons (TSNs) controlling the withdrawal reflexes, and decreased excitability of feeding decision-making neuron B51, respectively. Recently, 14 days of food deprivation (14DFD) was reported to break the co-expression of sensitization and feeding suppression in Aplysia without health deterioration. Specifically, under 14DFD, sensitization was completely prevented while feeding suppression was present albeit attenuated. This study explored the cellular mechanisms underlying the absent sensitization and reduced feeding suppression under 14DFD. A reduced preparation was used to evaluate the short-term cellular modifications induced by delivering an aversive training protocol in vitro. TSN excitability failed to increase following in vitro training under 14DFD, suggesting that the lack of sensitization may be a consequence of the fact that TSN excitability failed to increase. B51 excitability also failed to decrease following in vitro training, indicating that additional neurons may contribute to the conserved albeit reduced feeding suppression in 14DFD animals. This study lays the foundations for the future use of the Aplysia model system to investigate the mechanisms underlying the memory impairments induced by prolonged food deprivation.
Topics: Animals; Aplysia; Aversive Therapy; Feeding Behavior; Food Deprivation; Invertebrates; Learning; Memory, Short-Term; Reflex; Sensory Receptor Cells
PubMed: 34757110
DOI: 10.1016/j.bbr.2021.113646 -
Current Biology : CB Mar 2021Autotomy, the voluntary shedding of a body part, is common to distantly-related animals such as arthropods, gastropods, asteroids, amphibians, and lizards. Autotomy is...
Autotomy, the voluntary shedding of a body part, is common to distantly-related animals such as arthropods, gastropods, asteroids, amphibians, and lizards. Autotomy is generally followed by regeneration of shed terminal body parts, such as appendages or tails. Here, we identify a new type of extreme autotomy in two species of sacoglossan sea slug (Mollusca: Gastropoda). Surprisingly, they shed the main body, including the whole heart, and regenerated a new body. In contrast, the shed body did not regenerate the head. These sacoglossans can incorporate chloroplasts from algal food into their cells to utilise for photosynthesis (kleptoplasty), and we propose that this unique characteristic may facilitate survival after autotomy and subsequent regeneration.
Topics: Animals; Aplysia; Behavior, Animal; Chloroplasts; Photosynthesis; Regeneration
PubMed: 33689716
DOI: 10.1016/j.cub.2021.01.014 -
Learning & Memory (Cold Spring Harbor,... Apr 2014Neurotrophins are critically involved in developmental processes such as neuronal cell survival, growth, and differentiation, as well as in adult synaptic plasticity...
Neurotrophins are critically involved in developmental processes such as neuronal cell survival, growth, and differentiation, as well as in adult synaptic plasticity contributing to learning and memory. Our previous studies examining neurotrophins and memory formation in Aplysia showed that a TrkB ligand is required for MAPK activation, long-term synaptic facilitation (LTF), and long-term memory (LTM) for sensitization. These studies indicate that neurotrophin-like molecules in Aplysia can act as key elements in a functionally conserved TrkB signaling pathway. Here we report that we have cloned and characterized a novel neurotrophic factor, Aplysia cysteine-rich neurotrophic factor (apCRNF), which shares classical structural and functional characteristics with mammalian neurotrophins. We show that apCRNF (1) is highly enriched in the CNS, (2) enhances neurite elongation and branching, (3) interacts with mammalian TrkB and p75(NTR), (4) is released from Aplysia CNS in an activity-dependent fashion, (5) facilitates MAPK activation in a tyrosine kinase dependent manner in response to sensitizing stimuli, and (6) facilitates the induction of LTF. These results show that apCRNF is a native neurotrophic factor in Aplysia that can engage the molecular and synaptic mechanisms underlying memory formation.
Topics: Amino Acid Sequence; Animals; Aplysia; Cell Enlargement; Cells, Cultured; Central Nervous System; Cloning, Molecular; Long-Term Potentiation; Lymnaea; MAP Kinase Signaling System; Molecular Sequence Data; Motor Neurons; Nerve Growth Factors; Nerve Tissue Proteins; Neurites; Protein-Tyrosine Kinases; Rats; Receptors, Growth Factor; Receptors, Nerve Growth Factor; Sensory Receptor Cells; Species Specificity; Synapses
PubMed: 24639488
DOI: 10.1101/lm.033662.113 -
Current Biology : CB Oct 2012When an animal is reminded of a prior experience and shortly afterward treated with a protein synthesis inhibitor, the consolidated memory for the experience can be...
When an animal is reminded of a prior experience and shortly afterward treated with a protein synthesis inhibitor, the consolidated memory for the experience can be disrupted; by contrast, protein synthesis inhibition without prior reminding commonly does not disrupt long-term memory [1-3]. Such results imply that the reminding triggers reconsolidation of the memory. Here, we asked whether the behavioral and synaptic changes associated with the memory for long-term sensitization (LTS) of the siphon-withdrawal reflex in the marine snail Aplysia californica [4, 5] could undergo reconsolidation. In support of this idea, we found that when sensitized animals were given abbreviated reminder sensitization training 48-96 hr after the original sensitization training, followed by treatment with the protein synthesis inhibitor anisomycin, LTS was disrupted. We also found that long-term (≥ 24 hr) facilitation (LTF) [6], which can be induced in the monosynaptic connection between Aplysia sensory and motor neurons in dissociated cell culture by multiple spaced pulses of the endogenous facilitatory transmitter serotonin (5-HT) [7, 8], could be eliminated by treating the synapses with one reminder pulse of 5-HT, followed by anisomycin, at 48 hr after the original training. Our results provide a simple model system for understanding the synaptic basis of reconsolidation.
Topics: Analysis of Variance; Animals; Anisomycin; Aplysia; Behavior, Animal; Cells, Cultured; Memory, Long-Term; Motor Neurons; Protein Synthesis Inhibitors; Reflex; Sensory Receptor Cells; Serotonin; Synapses
PubMed: 22885063
DOI: 10.1016/j.cub.2012.07.038 -
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 -
The Journal of Neuroscience : the... Apr 2010Synaptic plasticity and learning involve different mechanisms depending on the following: (1) the stage of plasticity and (2) the history of plasticity, or... (Comparative Study)
Comparative Study
Synaptic plasticity and learning involve different mechanisms depending on the following: (1) the stage of plasticity and (2) the history of plasticity, or metaplasticity. However, little is known about how these two factors are related. We have addressed that question by examining mechanisms of synaptic plasticity during short-term and intermediate-term behavioral sensitization and dishabituation in a semi-intact preparation of the Aplysia siphon-withdrawal reflex. Dishabituation differs from sensitization in that it is preceded by habituation, and is thus a paradigm for metaplasticity. We find that whereas facilitation during short-term sensitization by one tail shock involves presynaptic covalent modifications by protein kinase A (PKA) and CamKII, facilitation during intermediate-term sensitization by four shocks involves both presynaptic (PKA, CaMKII) and postsynaptic (Ca(2+), CaMKII) covalent modifications, as well as both presynaptic and postsynaptic protein synthesis. The facilitation also involves presynaptic spike broadening 2.5 min after either one or four shocks, but not at later times. Dishabituation by four shocks differs from sensitization in several ways. First, it does not involve PKA or CaMKII, but rather involves presynaptic PKC. In addition, unlike sensitization with the same shock, dishabituation by four shocks does not involve protein synthesis or presynaptic spike broadening, and it also does not involve postsynaptic Ca(2+). These results demonstrate that not only the mechanisms but also the site of plasticity depend on both the stage of plasticity and metaplasticity during memory formation.
Topics: Animals; Aplysia; Excitatory Postsynaptic Potentials; In Vitro Techniques; Memory; Neuronal Plasticity; Presynaptic Terminals; Synaptic Transmission; Time Factors
PubMed: 20410130
DOI: 10.1523/JNEUROSCI.4947-09.2010 -
Brain Research Dec 1988Selected neurons of the abdominal ganglion of Aplysia californica were voltage-clamped and intracellular free Ca [( Ca2+]i) and Na [( Na+]i) concentrations were...
Selected neurons of the abdominal ganglion of Aplysia californica were voltage-clamped and intracellular free Ca [( Ca2+]i) and Na [( Na+]i) concentrations were monitored with ion selective microelectrodes. Reducing [Na+]o from 500 mM (normal seawater, NSW) to 5 mM resulted in a decrease of the potential measured by the Ca electrode (VCa). Increasing [Ca2+]o from 10 to 50 mM increased [Ca2+]i two-fold, keeping [Ca2+]o at 50 mM and decreasing [Na+]o to 5 mM still led to a decrease in VCa. With 100 mM [Ca2+]o, which also increased [Ca2+]i, decreasing [Na+]o increased VCa in two of the eight cells tested. This indicates that in normal or moderately high resting [Ca2+]i, Ca2+ extrusion by Na/Ca exchange (forward mode) is not essential for [Ca2+]i buffering. [Na+]i was 12.9 +/- 3.6 mM (S.E.M., n = 7) in NSW; reducing [Na+]o to 5 mM decreased [Na+]i to 2.0 +/- 1.1 mM (S.E.M.). Keeping [Na+]o at 5 mM and increasing [Ca2+]o from 10 to 20 mM further decreased [Na+]i to about 1.0 mM, evidence of Na/Ca exchange operating in the reverse mode. Attempts to increase [Ca2+]i by bath application of the Ca ionophores A23187, X537A, ionomycin or ETH 1001 resulted in no measurable change of the resting [Ca2+]i. Application of Ouabain caused an apparent increase in [Ca2+]i in two of the six cells tested. In cells injected with the metallochromic indicator arsenazo III (AIII), the rate of the falling phase of the AIII absorbance increase, following a voltage-clamp pulse, was significantly slower in 5 mM [Na+]o. This indicates that in its forward mode Na-Ca exchange is active in clearing large submembrane increases in [Ca2+]i.
Topics: Animals; Aplysia; Calcium; Fluorescent Dyes; Membrane Potentials; Neurons; Sodium
PubMed: 3208137
DOI: 10.1016/0006-8993(88)90447-7 -
Cell Dec 2006Molecular analyses of Aplysia, a well-established model organism for cellular and systems neural science, have been seriously handicapped by a lack of adequate genomic...
Molecular analyses of Aplysia, a well-established model organism for cellular and systems neural science, have been seriously handicapped by a lack of adequate genomic information. By sequencing cDNA libraries from the central nervous system (CNS), we have identified over 175,000 expressed sequence tags (ESTs), of which 19,814 are unique neuronal gene products and represent 50%-70% of the total Aplysia neuronal transcriptome. We have characterized the transcriptome at three levels: (1) the central nervous system, (2) the elementary components of a simple behavior: the gill-withdrawal reflex-by analyzing sensory, motor, and serotonergic modulatory neurons, and (3) processes of individual neurons. In addition to increasing the amount of available gene sequences of Aplysia by two orders of magnitude, this collection represents the largest database available for any member of the Lophotrochozoa and therefore provides additional insights into evolutionary strategies used by this highly successful diversified lineage, one of the three proposed superclades of bilateral animals.
Topics: Animals; Aplysia; Central Nervous System; Databases, Genetic; Evolution, Molecular; Expressed Sequence Tags; Ganglia, Invertebrate; Gills; Nerve Net; Neurons; Phylogeny; Synaptic Transmission; Transcription, Genetic
PubMed: 17190607
DOI: 10.1016/j.cell.2006.09.052 -
Journal of Visualized Experiments : JoVE Jun 2010Recording from key nerves and muscles of Aplysia during feeding behavior allows us to study the patterns of neural control in an intact animal. Simultaneously recording...
Recording from key nerves and muscles of Aplysia during feeding behavior allows us to study the patterns of neural control in an intact animal. Simultaneously recording from multiple nerves and muscles gives us precise information about the timing of neural activity. Previous recording methods have worked for two electrodes, but the study of additional nerves or muscles required combining and averaging the recordings of multiple animals, which made it difficult to determine fine details of timing and phasing, because of variability from response to response, and from animal to animal. Implanting four individual electrodes has a very low success rate due to the formation of adhesions that prevent animals from performing normal feeding movements. We developed a new method of electrode fabrication that reduces the bulk of the electrodes inside the animal allowing for normal feeding movements. Using a combination of glues to attach the electrodes results in a more reliable insulation of the electrode which lasts longer, making it possible to record for periods as long as a week. The fabrication technique that we describe could be extended to incorporate several additional electrodes, and would be applicable to vertebrate animals.
Topics: Animals; Aplysia; Electrodes, Implanted; Electrophysiology; Ganglia, Invertebrate; Mouth Mucosa; Muscles; Neuromuscular Junction; Neurons
PubMed: 20543773
DOI: 10.3791/1791