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Frontiers in Behavioral Neuroscience 2022Learning to identify and predict threats is a basic skill that allows animals to avoid harm. Studies in invertebrates like , and have revealed that the basic mechanisms... (Review)
Review
Learning to identify and predict threats is a basic skill that allows animals to avoid harm. Studies in invertebrates like , and have revealed that the basic mechanisms of learning and memory are conserved. We will summarize these studies and highlight the common pathways and mechanisms in invertebrate fear-associated behavioral changes. Fear conditioning studies utilizing electric shock in and have demonstrated that serotonin or dopamine are typically involved in relaying aversive stimuli, leading to changes in intracellular calcium levels and increased presynaptic neurotransmitter release and short-term changes in behavior. Long-term changes in behavior typically require multiple, spaced trials, and involve changes in gene expression. studies have demonstrated these basic aversive learning principles as well; however, fear conditioning has yet to be explicitly demonstrated in this model due to stimulus choice. Because predator-prey relationships can be used to study learned fear in a naturalistic context, this review also summarizes what is known about predator-induced behaviors in these three organisms, and their potential applications for future investigations into fear conditioning.
PubMed: 36439964
DOI: 10.3389/fnbeh.2022.1008818 -
Cold Spring Harbor Perspectives in... Dec 2019When protein/peptides aggregate, they usually form the amyloid state consisting of cross β-sheet structure built by repetitively stacked β-strands forming long... (Review)
Review
When protein/peptides aggregate, they usually form the amyloid state consisting of cross β-sheet structure built by repetitively stacked β-strands forming long fibrils. Amyloids are usually associated with disease including Alzheimer's. However, amyloid has many useful features. It efficiently transforms protein from the soluble to the insoluble state in an essentially two-state process, while its repetitive structure provides high stability and a robust prion-like replication mechanism. Accordingly, amyloid is used by nature in multifaceted and ingenious ways of life, ranging from bacteria and fungi to mammals. These include (1) Structure: Templating for small chemical molecules (Pmel17), biofilm formation in bacteria (curli), assisting aerial hyphae formation in streptomycetes (chaplins) or monolayer formation at a surface (hydrophobins). (2) Reservoirs: A storage state for peptide/proteins to protect them from their surroundings or vice versa (storage of peptide hormones in mammalian secretory granules or major basic protein in eosinophils). (3) Information carriers: The fungal immune system (HET-s prion in , yeast prions) or long-term memory (e.g., mnemons in yeast, cytoplasmic polyadenylation element-binding protein in aplysia). Aggregation is also used to (4) "suppress" the function of the soluble protein (e.g., Cdc19 in yeast stress granules), or (5) "signaling" through formation of oligomers (e.g., HET-s prion, necroptosis-related proteins RIP1/RIP3). This review summarizes current knowledge on functional amyloids with a focus on the amyloid systems curli in bacteria, HET-s prion in , and peptide hormone storage in mammals together with an attempt to highlight differences between functional and disease-associated amyloids.
Topics: Amyloid; Bacteria; Fungi; Structure-Activity Relationship
PubMed: 31088827
DOI: 10.1101/cshperspect.a033860 -
JACC. Cardiovascular Interventions Dec 2021
Topics: Heart Ventricles; Humans; Shock, Cardiogenic; Treatment Outcome
PubMed: 34949395
DOI: 10.1016/j.jcin.2021.10.012 -
Trends in Neurosciences Mar 2023Chronic pain caused by injury or disease of the nervous system (neuropathic pain) has been linked to persistent electrical hyperactivity of the sensory neurons... (Review)
Review
Chronic pain caused by injury or disease of the nervous system (neuropathic pain) has been linked to persistent electrical hyperactivity of the sensory neurons (nociceptors) specialized to detect damaging stimuli and/or inflammation. This pain and hyperactivity are considered maladaptive because both can persist long after injured tissues have healed and inflammation has resolved. While the assumption of maladaptiveness is appropriate in many diseases, accumulating evidence from diverse species, including humans, challenges the assumption that neuropathic pain and persistent nociceptor hyperactivity are always maladaptive. We review studies indicating that persistent nociceptor hyperactivity has undergone evolutionary selection in widespread, albeit selected, animal groups as a physiological response that can increase survival long after bodily injury, using both highly conserved and divergent underlying mechanisms.
Topics: Humans; Animals; Nociceptors; Sensory Receptor Cells; Neuralgia; Adaptation, Physiological
PubMed: 36610893
DOI: 10.1016/j.tins.2022.12.007 -
Neuropharmacology Nov 2021Glutamate (Glu) is the primary excitatory transmitter in the mammalian brain. But, we know little about the evolutionary history of this adaptation, including the... (Review)
Review
Glutamate (Glu) is the primary excitatory transmitter in the mammalian brain. But, we know little about the evolutionary history of this adaptation, including the selection of l-glutamate as a signaling molecule in the first place. Here, we used comparative metabolomics and genomic data to reconstruct the genealogy of glutamatergic signaling. The origin of Glu-mediated communications might be traced to primordial nitrogen and carbon metabolic pathways. The versatile chemistry of L-Glu placed this molecule at the crossroad of cellular biochemistry as one of the most abundant metabolites. From there, innovations multiplied. Many stress factors or injuries could increase extracellular glutamate concentration, which led to the development of modular molecular systems for its rapid sensing in bacteria and archaea. More than 20 evolutionarily distinct families of ionotropic glutamate receptors (iGluRs) have been identified in eukaryotes. The domain compositions of iGluRs correlate with the origins of multicellularity in eukaryotes. Although L-Glu was recruited as a neuro-muscular transmitter in the early-branching metazoans, it was predominantly a non-neuronal messenger, with a possibility that glutamatergic synapses evolved more than once. Furthermore, the molecular secretory complexity of glutamatergic synapses in invertebrates (e.g., Aplysia) can exceed their vertebrate counterparts. Comparative genomics also revealed 15+ subfamilies of iGluRs across Metazoa. However, most of this ancestral diversity had been lost in the vertebrate lineage, preserving AMPA, Kainate, Delta, and NMDA receptors. The widespread expansion of glutamate synapses in the cortical areas might be associated with the enhanced metabolic demands of the complex brain and compartmentalization of Glu signaling within modular neuronal ensembles.
Topics: Animals; Biological Evolution; Glutamic Acid; Receptors, Glutamate; Signal Transduction; Synapses
PubMed: 34343611
DOI: 10.1016/j.neuropharm.2021.108740 -
Proceedings of the National Academy of... Sep 2021Habituation and sensitization (nonassociative learning) are among the most fundamental forms of learning and memory behavior present in organisms that enable adaptation...
Habituation and sensitization (nonassociative learning) are among the most fundamental forms of learning and memory behavior present in organisms that enable adaptation and learning in dynamic environments. Emulating such features of intelligence found in nature in the solid state can serve as inspiration for algorithmic simulations in artificial neural networks and potential use in neuromorphic computing. Here, we demonstrate nonassociative learning with a prototypical Mott insulator, nickel oxide (NiO), under a variety of external stimuli at and above room temperature. Similar to biological species such as , habituation and sensitization of NiO possess time-dependent plasticity relying on both strength and time interval between stimuli. A combination of experimental approaches and first-principles calculations reveals that such learning behavior of NiO results from dynamic modulation of its defect and electronic structure. An artificial neural network model inspired by such nonassociative learning is simulated to show advantages for an unsupervised clustering task in accuracy and reducing catastrophic interference, which could help mitigate the stability-plasticity dilemma. Mott insulators can therefore serve as building blocks to examine learning behavior noted in biology and inspire new learning algorithms for artificial intelligence.
Topics: Algorithms; Animals; Aplysia; Artificial Intelligence; Electrons; Insulator Elements; Models, Neurological; Neural Networks, Computer; Neuronal Plasticity; Nickel; Synapses
PubMed: 34531299
DOI: 10.1073/pnas.2017239118 -
Molecules (Basel, Switzerland) Feb 2020Invertebrates are an important source of structurally-diverse and biologically-active halogenated metabolites. The sea hare Rang has long been known to possess... (Review)
Review
Invertebrates are an important source of structurally-diverse and biologically-active halogenated metabolites. The sea hare Rang has long been known to possess halogenated metabolites of dietary origin that are used as a self-defense mechanism. The compounds from Rang are comprised mainly of terpenoids and small percentages of C-15 acetogenins, indoles, macrolides, sterols and alkaloids with potent cytotoxic, anti-microbial and anti-inflammatory properties. For decades the metabolites discovered have been investigated for their medical and pharmaceutical applications, so much so that the ecological role of the metabolites has been overlooked. The interaction between Rang and its diet that is comprised of seaweed can provide information into the distribution and diversity of the seaweed, the application of bioaccumulated secondary metabolites as part of its defense mechanism and the potential roles of these metabolites for adaptation in the marine environment. This paper compiles the diversity of halogenated secondary metabolites documented from Rang.
Topics: Acetogenins; Alkaloids; Animals; Aplysia; Halogenation; Indoles; Macrolides; Seaweed; Sterols
PubMed: 32070000
DOI: 10.3390/molecules25040815 -
Small GTPases 2021Since the discovery by Madaule and Axel in 1985 of the first Ras homologue (Rho) protein in and its human orthologue RhoB, membership in the Rho GTPase family has grown... (Review)
Review
Since the discovery by Madaule and Axel in 1985 of the first Ras homologue (Rho) protein in and its human orthologue RhoB, membership in the Rho GTPase family has grown to 20 proteins, with representatives in all eukaryotic species. These GTPases are molecular switches that cycle between active (GTP bound) and inactivate (GDP bound) states. The exchange of GDP for GTP on Rho GTPases is facilitated by guanine exchange factors (GEFs). Approximately 80 Rho GEFs have been identified to date, and only a few GEFs associate with microtubules. The guanine nucleotide exchange factor H1, GEF-H1, is a unique GEF that associates with microtubules and is regulated by the polymerization state of microtubule networks. This review summarizes the regulation and functions of GEF-H1 and discusses the roles of GEF-H1 in human diseases.
Topics: Animals; Disease; Gene Expression Regulation; Humans; Microtubules; Rho Guanine Nucleotide Exchange Factors
PubMed: 33126816
DOI: 10.1080/21541248.2020.1840889 -
Frontiers in Neuroscience 2020The nervous system (NS) of invertebrates and vertebrates is composed of two main types of cells: neurons and glia. In both types of organisms, nerve cells have... (Review)
Review
The nervous system (NS) of invertebrates and vertebrates is composed of two main types of cells: neurons and glia. In both types of organisms, nerve cells have similarities in biochemistry and functionality. The neurons are in charge of the synapse, and the glial cells are in charge of important functions of neuronal and homeostatic modulation. Knowing the mechanisms by which NS cells work is important in the biomedical area for the diagnosis and treatment of neurological disorders. For this reason, cellular and animal models to study the properties and characteristics of the NS are always sought. Marine invertebrates are strategic study models for the biological sciences. The sea slug and the squid are two examples of marine key organisms in the neurosciences field. The principal characteristic of marine invertebrates is that they have a simpler NS that consists of few and larger cells, which are well organized and have accessible structures. As well, the close phylogenetic relationship between Chordata and Echinodermata constitutes an additional advantage to use these organisms as a model for the functionality of neuronal cells and their cellular plasticity. Currently, there is great interest in analyzing the signaling processes between neurons and glial cells, both in vertebrates and in invertebrates. However, only few types of glial cells of invertebrates, mostly insects, have been studied, and it is important to consider marine organisms' research. For this reason, the objective of the review is to present an update of the most relevant information that exists around the physiology of marine invertebrate neuronal and glial cells.
PubMed: 32132895
DOI: 10.3389/fnins.2020.00121 -
Frontiers in Neuroscience 2022New tools for monitoring and manipulating neural activity have been developed with steadily improving functionality, specificity, and reliability, which are critical... (Review)
Review
New tools for monitoring and manipulating neural activity have been developed with steadily improving functionality, specificity, and reliability, which are critical both for mapping neural circuits and treating neurological diseases. This review focuses on the use of an invertebrate animal, the marine mollusk , in the development of novel neurotechniques. We review the basic physiological properties of neurons and discuss the specific aspects that make it advantageous for developing novel neural interfaces: First, nerves consist only of unmyelinated axons with various diameters, providing a particularly useful model of the unmyelinated C fibers in vertebrates that are known to carry important sensory information, including those that signal pain. Second, neural tissues can last for a long period in an experimental setup. This allows comprehensive tests such as the exploration of parameter space on the same nerve to avoid variability between animals and minimize animal use. Third, nerves in large can be many centimeters in length, making it possible to easily discriminate axons with different diameters based on their conduction velocities. nerves are a particularly good approximation of the unmyelinated C fibers, which are hard to stimulate, record, and differentiate from other nerve fibers in vertebrate animal models using epineural electrodes. Fourth, neurons in are large, uniquely identifiable, and electrically compact. For decades, researchers have used for the development of many novel neurotechnologies. Examples include high-frequency alternating current (HFAC), focused ultrasound (FUS), optical neural stimulation, recording, and inhibition, microelectrode arrays, diamond electrodes, carbon fiber microelectrodes, microscopic magnetic stimulation and magnetic resonance electrical impedance tomography (MREIT). We also review a specific example that illustrates the power of for accelerating technology development: selective infrared neural inhibition of small-diameter unmyelinated axons, which may lead to a translationally useful treatment in the future. Generally, is suitable for testing modalities whose mechanism involves basic biophysics that is likely to be similar across species. As a tractable experimental system, can help the rapid development of novel neuromodulation technologies.
PubMed: 36620467
DOI: 10.3389/fnins.2022.1080027