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Mayorova TD, Koch TL, Kachar B, Jung JH, Reese TS, Smith CL. Placozoan secretory cell types implicated in feeding, innate immunity and regulation of behavior. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.09.18.613768. [PMID: 39372748 PMCID: PMC11452194 DOI: 10.1101/2024.09.18.613768] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/08/2024]
Abstract
Placozoa are millimeter-sized, flat, irregularly shaped ciliated animals that crawl on surfaces in warm oceans feeding on biofilms, which they digest externally. They stand out from other animals due to their simple body plans. They lack organs, body cavities, muscles and a nervous system and have only seven broadly defined morphological cell types, each with a unique distribution. Analyses of single cell transcriptomes of four species of placozoans revealed greater diversity of secretory cell types than evident from morphological studies, but the locations of many of these new cell types were unknown and it was unclear which morphological cell types they represent. Furthermore, there were contradictions between the conclusions of previous studies and the single cell RNAseq studies. To address these issues, we used mRNA probes for genes encoding secretory products expressed in different metacells in Trichoplax adhaerens to localize cells in whole mounts and in dissociated cell cultures, where their morphological features could be visualized and identified. The nature and functions of their secretory granules were further investigated with electron microscopic techniques and by imaging secretion in live animals during feeding episodes. We found that two cell types participate in disintegrating prey, one resembling a lytic cell type in mammals and another combining features of zymogen gland cells and enterocytes. We identified secretory epithelial cells expressing glycoproteins or short peptides implicated in defense. We located seven peptidergic cell types and two types of mucocytes. Our findings reveal mechanisms that placozoans use to feed and protect themselves from pathogens and clues about neuropeptidergic signaling. We compare placozoan secretory cell types with cell types in other animal phyla to gain insight about general evolutionary trends in cell type diversification, as well as pathways leading to the emergence of synapomorphies.
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Karkali K, Martín-Blanco E. The evolutionary and mechanical principles shaping the Drosophila embryonic ventral nerve cord. Cells Dev 2024; 180:203973. [PMID: 39490740 DOI: 10.1016/j.cdev.2024.203973] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2024] [Revised: 09/19/2024] [Accepted: 10/23/2024] [Indexed: 11/05/2024]
Abstract
The establishment of communication circuits requires bringing sources and targets into contact, either directly or indirectly. The Central Nervous System (CNS)'s ability to interpret the environment and generate precise responses depends on the functional efficiency of its neural network, which in turn relies on the 3D spatial organization of its constituents, mainly neurons and glia. Throughout evolution, sensory integration and motor response coordination became linked with the merging of the brain and nerve cord (NC) in the urbilaterian CNS. In most arthropods, the NC follows a specific topological plan and consists of a fixed number of neuromeres (thoracic and abdominal ganglia with commissural interconnections and a single terminal ganglion). The number, spacing, and fusion of neuromeres are species-specific and can change during embryogenesis or post-embryonic life. During Drosophila embryogenesis, the NC condenses along the Anterior-Posterior (AP) axis in a stereotypical manner, bringing neuromeres closer together. This process has revealed several key parameters, including its morphogenetic mechanics, the roles of various cellular, molecular, and structural components, and the functional purpose of its balanced design. The embryonic NC serves as a valuable model for investigating the ancient mechanisms underlying the structural organization, sensory integration, and motor coordination of the CNS. While many aspects of ganglionic fusion remain unknown, ongoing research promises to provide a more comprehensive understanding of the mechanical and evolutionary principles that govern it.
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Affiliation(s)
- Katerina Karkali
- Instituto de Biología Molecular de Barcelona (CSIC), Parc Cientific de Barcelona, Baldiri Reixac 10-12, 08028 Barcelona, Spain.
| | - Enrique Martín-Blanco
- Instituto de Biología Molecular de Barcelona (CSIC), Parc Cientific de Barcelona, Baldiri Reixac 10-12, 08028 Barcelona, Spain
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3
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Yaguchi J, Sakai K, Horiuchi A, Yamamoto T, Yamashita T, Yaguchi S. Light-modulated neural control of sphincter regulation in the evolution of through-gut. Nat Commun 2024; 15:8881. [PMID: 39424783 PMCID: PMC11489725 DOI: 10.1038/s41467-024-53203-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2024] [Accepted: 10/04/2024] [Indexed: 10/21/2024] Open
Abstract
The development of a continuous digestive tract, or through-gut, represents a key milestone in bilaterian evolution. However, the regulatory mechanisms in ancient bilaterians (urbilaterians) are not well understood. Our study, using larval sea urchins as a model, reveals a sophisticated system that prevents the simultaneous opening of the pylorus and anus, entry and exit points of the gut. This regulation is influenced by external light, with blue light affecting the pylorus via serotonergic neurons and both blue and longer wavelengths controlling the anus through cholinergic and dopaminergic neurons. These findings provide new insights into the neural orchestration of sphincter control in a simplified through-gut, which includes the esophagus, stomach, and intestine. Here, we propose that the emergence of the earliest urbilaterian through-gut was accompanied by the evolution of neural systems regulating sphincters in response to light, shedding light on the functional regulation of primordial digestive systems.
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Affiliation(s)
- Junko Yaguchi
- Shimoda Marine Research Center, University of Tsukuba, 5-10-1 Shimoda, Shizuoka, 415-0025, Japan
| | - Kazumi Sakai
- Department of Biophysics, Graduate School of Science, Kyoto University, Kitashirakawa-Oiwake, Sakyo-ku, Kyoto, Kyoto, 606-8502, Japan
| | - Atsushi Horiuchi
- Department of Biophysics, Graduate School of Science, Kyoto University, Kitashirakawa-Oiwake, Sakyo-ku, Kyoto, Kyoto, 606-8502, Japan
| | - Takashi Yamamoto
- Graduate School of Integrated Sciences for Life, Hiroshima University, Higashi-Hiroshima, Hiroshima, 739-8526, Japan
| | - Takahiro Yamashita
- Department of Biophysics, Graduate School of Science, Kyoto University, Kitashirakawa-Oiwake, Sakyo-ku, Kyoto, Kyoto, 606-8502, Japan
| | - Shunsuke Yaguchi
- Shimoda Marine Research Center, University of Tsukuba, 5-10-1 Shimoda, Shizuoka, 415-0025, Japan.
- Japan Science and Technology Agency, PRESTO, 7 Gobancho, Chiyoda-ku, 102-0076, Tokyo, Japan.
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Puri D, Allison KR. Escherichia coli self-organizes developmental rosettes. Proc Natl Acad Sci U S A 2024; 121:e2315850121. [PMID: 38814871 PMCID: PMC11161754 DOI: 10.1073/pnas.2315850121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2023] [Accepted: 05/01/2024] [Indexed: 06/01/2024] Open
Abstract
Rosettes are self-organizing, circular multicellular communities that initiate developmental processes, like organogenesis and embryogenesis, in complex organisms. Their formation results from the active repositioning of adhered sister cells and is thought to distinguish multicellular organisms from unicellular ones. Though common in eukaryotes, this multicellular behavior has not been reported in bacteria. In this study, we found that Escherichia coli forms rosettes by active sister-cell repositioning. After division, sister cells "fold" to actively align at the 2- and 4-cell stages of clonal division, thereby producing rosettes with characteristic quatrefoil configuration. Analysis revealed that folding follows an angular random walk, composed of ~1 µm strokes and directional randomization. We further showed that this motion was produced by the flagellum, the extracellular tail whose rotation generates swimming motility. Rosette formation was found to require de novo flagella synthesis suggesting it must balance the opposing forces of Ag43 adhesion and flagellar propulsion. We went on to show that proper rosette formation was required for subsequent morphogenesis of multicellular chains, rpoS gene expression, and formation of hydrostatic clonal-chain biofilms. Moreover, we found self-folding rosette-like communities in the standard motility assay, indicating that this behavior may be a general response to hydrostatic environments in E. coli. These findings establish self-organization of clonal rosettes by a prokaryote and have implications for evolutionary biology, synthetic biology, and medical microbiology.
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Affiliation(s)
- Devina Puri
- Department of Biomedical Engineering, Emory University and Georgia Institute of Technology, Atlanta, GA30322
| | - Kyle R. Allison
- Department of Biomedical Engineering, Emory University and Georgia Institute of Technology, Atlanta, GA30322
- Division of Infectious Diseases, Department of Medicine, Emory University School of Medicine, Atlanta, GA30322
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5
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Johnson CJ, Razy-Krajka F, Zeng F, Piekarz KM, Biliya S, Rothbächer U, Stolfi A. Specification of distinct cell types in a sensory-adhesive organ important for metamorphosis in tunicate larvae. PLoS Biol 2024; 22:e3002555. [PMID: 38478577 PMCID: PMC10962819 DOI: 10.1371/journal.pbio.3002555] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2023] [Revised: 03/25/2024] [Accepted: 02/21/2024] [Indexed: 03/22/2024] Open
Abstract
The papillae of tunicate larvae contribute sensory, adhesive, and metamorphosis-regulating functions that are crucial for the biphasic lifestyle of these marine, non-vertebrate chordates. We have identified additional molecular markers for at least 5 distinct cell types in the papillae of the model tunicate Ciona, allowing us to further study the development of these organs. Using tissue-specific CRISPR/Cas9-mediated mutagenesis and other molecular perturbations, we reveal the roles of key transcription factors and signaling pathways that are important for patterning the papilla territory into a highly organized array of different cell types and shapes. We further test the contributions of different transcription factors and cell types to the production of the adhesive glue that allows for larval attachment during settlement, and to the processes of tail retraction and body rotation during metamorphosis. With this study, we continue working towards connecting gene regulation to cellular functions that control the developmental transition between the motile larva and sessile adult of Ciona.
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Affiliation(s)
- Christopher J Johnson
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, Georgia, United States of America
| | - Florian Razy-Krajka
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, Georgia, United States of America
| | - Fan Zeng
- Department of Zoology, University of Innsbruck, Innsbruck, Austria
| | - Katarzyna M Piekarz
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, Georgia, United States of America
| | - Shweta Biliya
- Molecular Evolution Core, Petit H. Parker Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, Georgia, United States of America
| | - Ute Rothbächer
- Department of Zoology, University of Innsbruck, Innsbruck, Austria
| | - Alberto Stolfi
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, Georgia, United States of America
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Brunet T. Cell contractility in early animal evolution. Curr Biol 2023; 33:R966-R985. [PMID: 37751712 DOI: 10.1016/j.cub.2023.07.054] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/28/2023]
Abstract
Tissue deformation mediated by collective cell contractility is a signature characteristic of animals. In most animals, fast and reversible contractions of muscle cells mediate behavior, while slow and irreversible contractions of epithelial or mesenchymal cells play a key role in morphogenesis. Animal tissue contractility relies on the activity of the actin/myosin II complex (together referred to as 'actomyosin'), an ancient and versatile molecular machinery that performs a broad range of functions in development and physiology. This review synthesizes emerging insights from morphological and molecular studies into the evolutionary history of animal contractile tissue. The most ancient functions of actomyosin are cell crawling and cytokinesis, which are found in a wide variety of unicellular eukaryotes and in individual metazoan cells. Another contractile functional module, apical constriction, is universal in metazoans and shared with choanoflagellates, their closest known living relatives. The evolution of animal contractile tissue involved two key innovations: firstly, the ability to coordinate and integrate actomyosin assembly across multiple cells, notably to generate supracellular cables, which ensure tissue integrity but also allow coordinated morphogenesis and movements at the organism scale; and secondly, the evolution of dedicated contractile cell types for adult movement, belonging to two broad categories respectively defined by the expression of the fast (striated-type) and slow (smooth/non-muscle-type) myosin II paralogs. Both contractile cell types ancestrally resembled generic contractile epithelial or mesenchymal cells and might have played a versatile role in both behavior and morphogenesis. Modern animal contractile cells span a continuum between unspecialized contractile epithelia (which underlie behavior in modern placozoans), epithelia with supracellular actomyosin cables (found in modern sponges), epitheliomuscular tissues (with a concentration of actomyosin cables in basal processes, for example in sea anemones), and specialized muscle tissue that has lost most or all epithelial properties (as in ctenophores, jellyfish and bilaterians). Recent studies in a broad range of metazoans have begun to reveal the molecular basis of these transitions, powered by the elaboration of the contractile apparatus and the evolution of 'core regulatory complexes' of transcription factors specifying contractile cell identity.
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Affiliation(s)
- Thibaut Brunet
- Institut Pasteur, Université Paris-Cité, CNRS UMR3691, Evolutionary Cell Biology and Evolution of Morphogenesis Unit, 25-28 Rue du Docteur Roux, 75015 Paris, France.
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Rusin LY. Evolution of homology: From archetype towards a holistic concept of cell type. J Morphol 2023; 284:e21569. [PMID: 36789784 DOI: 10.1002/jmor.21569] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2022] [Revised: 01/10/2023] [Accepted: 02/13/2023] [Indexed: 02/16/2023]
Abstract
The concept of homology lies in the heart of comparative biological science. The distinction between homology as structure and analogy as function has shaped the evolutionary paradigm for a century and formed the axis of comparative anatomy and embryology, which accept the identity of structure as a ground measure of relatedness. The advent of single-cell genomics overturned the classical view of cell homology by establishing a backbone regulatory identity of cell types, the basic biological units bridging the molecular and phenotypic dimensions, to reveal that the cell is the most flexible unit of living matter and that many approaches of classical biology need to be revised to understand evolution and diversity at the cellular level. The emerging theory of cell types explicitly decouples cell identity from phenotype, essentially allowing for the divergence of evolutionarily related morphotypes beyond recognition, as well as it decouples ontogenetic cell lineage from cell-type phylogeny, whereby explicating that cell types can share common descent regardless of their structure, function or developmental origin. The article succinctly summarizes current progress and opinion in this field and formulates a more generalistic view of biological cell types as avatars, transient or terminal cell states deployed in a continuum of states by the developmental programme of one and the same omnipotent cell, capable of changing or combining identities with distinct evolutionary histories or inventing ad hoc identities that never existed in evolution or development. It highlights how the new logic grounded in the regulatory nature of cell identity transforms the concepts of cell homology and phenotypic stability, suggesting that cellular evolution is inherently and massively network-like, with one-to-one homologies being rather uncommon and restricted to shallower levels of the animal tree of life.
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Affiliation(s)
- Leonid Y Rusin
- Laboratory for Mathematic Methods and Models in Bioinformatics, Institute for Information Transmission Problems (Kharkevich Institute), Russian Academy of Sciences, Moscow, Russia
- EvoGenome Analytics LLC, Odintsovo, Moscow Region, Russia
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8
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Nielsen C. Hydrodynamics in early animal evolution. Biol Rev Camb Philos Soc 2023; 98:376-385. [PMID: 36216338 DOI: 10.1111/brv.12909] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2022] [Revised: 09/27/2022] [Accepted: 09/28/2022] [Indexed: 01/12/2023]
Abstract
Choanoflagellates and sponges feed by filtering microscopic particles from water currents created by the flagella of microvillar collar complexes situated on the cell bodies of the solitary or colonial choanoflagellates and on the choanocytes in sponges. The filtering mechanism has been known for more than a century, but only recently has the filtering process been studied in detail and also modelled, so that a detailed picture of the water currents has been obtained. In the solitary and most of the colonial choanoflagellates, the water flows freely around the cells, but in some forms, the cells are arranged in an open meshwork through which the water can be pumped. In the sponges, the choanocytes are located in choanocyte chambers (or choanocyte areas) with separate incurrent and excurrent canals/pores located in a larger body, which enables a fixed pattern of water currents through the collar complexes. Previous theories for the origin of sponges show evolutionary stages with choanocyte chambers without any opening or with only one opening, which makes separation of incurrent and excurrent impossible, and such stages must have been unable to feed. Therefore a new theory is proposed, which shows a continuous evolutionary lineage in which all stages are able to feed by means of the collar complexes.
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Affiliation(s)
- Claus Nielsen
- Natural History Museum of Denmark (University of Copenhagen), Zoological Museum, Universitetsparken 15, DK-2990, Copenhagen, Denmark
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9
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Duruz J, Sprecher SG. Evolution and Origins of Nervous Systems. Neurogenetics 2023. [DOI: 10.1007/978-3-031-07793-7_8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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10
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Brunet T, Booth DS. Cell polarity in the protist-to-animal transition. Curr Top Dev Biol 2023; 154:1-36. [PMID: 37100515 DOI: 10.1016/bs.ctdb.2023.03.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/08/2023]
Abstract
A signature feature of the animal kingdom is the presence of epithelia: sheets of polarized cells that both insulate the organism from its environment and mediate interactions with it. Epithelial cells display a marked apico-basal polarity, which is highly conserved across the animal kingdom, both in terms of morphology and of molecular regulators. How did this architecture first evolve? Although the last eukaryotic common ancestor almost certainly possessed a simple form of apico-basal polarity (marked by the presence of one or several flagella at a single cellular pole), comparative genomics and evolutionary cell biology reveal that the polarity regulators of animal epithelial cells have a surprisingly complex and stepwise evolutionary history. Here, we retrace their evolutionary assembly. We suggest that the "polarity network" that polarized animal epithelial cells evolved by integration of initially independent cellular modules that evolved at distinct steps of our evolutionary ancestry. The first module dates back to the last common ancestor of animals and amoebozoans and involved Par1, extracellular matrix proteins, and the integrin-mediated adhesion complex. Other regulators, such as Cdc42, Dlg, Par6 and cadherins evolved in ancient unicellular opisthokonts, and might have first been involved in F-actin remodeling and filopodial dynamics. Finally, the bulk of "polarity proteins" as well as specialized adhesion complexes evolved in the metazoan stem-line, in concert with the newly evolved intercellular junctional belts. Thus, the polarized architecture of epithelia can be understood as a palimpsest of components of distinct histories and ancestral functions, which have become tightly integrated in animal tissues.
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Moroz LL, Romanova DY. Alternative neural systems: What is a neuron? (Ctenophores, sponges and placozoans). Front Cell Dev Biol 2022; 10:1071961. [PMID: 36619868 PMCID: PMC9816575 DOI: 10.3389/fcell.2022.1071961] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2022] [Accepted: 12/13/2022] [Indexed: 12/24/2022] Open
Abstract
How to make a neuron, a synapse, and a neural circuit? Is there only one 'design' for a neural architecture with a universally shared genomic blueprint across species? The brief answer is "No." Four early divergent lineages from the nerveless common ancestor of all animals independently evolved distinct neuroid-type integrative systems. One of these is a subset of neural nets in comb jellies with unique synapses; the second lineage is the well-known Cnidaria + Bilateria; the two others are non-synaptic neuroid systems in sponges and placozoans. By integrating scRNA-seq and microscopy data, we revise the definition of neurons as synaptically-coupled polarized and highly heterogenous secretory cells at the top of behavioral hierarchies with learning capabilities. This physiological (not phylogenetic) definition separates 'true' neurons from non-synaptically and gap junction-coupled integrative systems executing more stereotyped behaviors. Growing evidence supports the hypothesis of multiple origins of neurons and synapses. Thus, many non-bilaterian and bilaterian neuronal classes, circuits or systems are considered functional rather than genetic categories, composed of non-homologous cell types. In summary, little-explored examples of convergent neuronal evolution in representatives of early branching metazoans provide conceptually novel microanatomical and physiological architectures of behavioral controls in animals with prospects of neuro-engineering and synthetic biology.
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Affiliation(s)
- Leonid L. Moroz
- Departments of Neuroscience and McKnight Brain Institute, University of Florida, Gainesville, FL, United States
- Whitney Laboratory for Marine Bioscience, University of Florida, St. Augustine, FL, United States
| | - Daria Y. Romanova
- Institute of Higher Nervous Activity and Neurophysiology of RAS, 5A Butlerova, Moscow, Russia
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12
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Lindemann CB. The flagellar germ-line hypothesis: How flagellate and ciliate gametes significantly shaped the evolution of organismal complexity. Bioessays 2021; 44:e2100143. [PMID: 34967029 DOI: 10.1002/bies.202100143] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2021] [Revised: 12/10/2021] [Accepted: 12/15/2021] [Indexed: 11/10/2022]
Abstract
This essay presents a hypothesis which contends that the development of organismic complexity in the eukaryotes depended extensively on propagation via flagellated and ciliated gametes. Organisms utilizing flagellate and ciliate gametes to propagate their germ line have contributed most of the organismic complexity found in the higher animals. The genes of the flagellum and the flagellar assembly system (intraflagellar transport) have played a disproportionately important role in the construction of complex tissues and organs. The hypothesis also proposes that competition between large numbers of haploid flagellated male gametes rigorously conserved the functionality of a key set of flagellar genes for more than 700 million years. This in turn has insured that a large set (>600) of highly functional cytoskeletal and signal pathway genes is always present in the lineage of organisms with flagellated or ciliated gametes to act as a dependable resource, or "toolkit," for organ elaboration.
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13
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Mayorova TD, Hammar K, Jung JH, Aronova MA, Zhang G, Winters CA, Reese TS, Smith CL. Placozoan fiber cells: mediators of innate immunity and participants in wound healing. Sci Rep 2021; 11:23343. [PMID: 34857844 PMCID: PMC8639732 DOI: 10.1038/s41598-021-02735-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2021] [Accepted: 11/19/2021] [Indexed: 12/22/2022] Open
Abstract
Placozoa is a phylum of non-bilaterian marine animals. These small, flat organisms adhere to the substrate via their densely ciliated ventral epithelium, which mediates mucociliary locomotion and nutrient uptake. They have only six morphological cell types, including one, fiber cells, for which functional data is lacking. Fiber cells are non-epithelial cells with multiple processes. We used electron and light microscopic approaches to unravel the roles of fiber cells in Trichoplax adhaerens, a representative member of the phylum. Three-dimensional reconstructions of serial sections of Trichoplax showed that each fiber cell is in contact with several other cells. Examination of fiber cells in thin sections and observations of live dissociated fiber cells demonstrated that they phagocytose cell debris and bacteria. In situ hybridization confirmed that fiber cells express genes involved in phagocytic activity. Fiber cells also are involved in wound healing as evidenced from microsurgery experiments. Based on these observations we conclude that fiber cells are multi-purpose macrophage-like cells. Macrophage-like cells have been described in Porifera, Ctenophora, and Cnidaria and are widespread among Bilateria, but our study is the first to show that Placozoa possesses this cell type. The phylogenetic distribution of macrophage-like cells suggests that they appeared early in metazoan evolution.
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Affiliation(s)
- Tatiana D Mayorova
- Laboratory of Neurobiology, National Institute of Neurological Disorders and Stroke, National Institutes of Health, 49 Convent Drive, Bethesda, MD, 20892, USA.
| | - Katherine Hammar
- Central Microscopy Facility, Marine Biological Laboratory, 7 MBL Street, Woods Hole, MA, 02543, USA
| | - Jae H Jung
- Laboratory of Neurobiology, National Institute of Neurological Disorders and Stroke, National Institutes of Health, 49 Convent Drive, Bethesda, MD, 20892, USA
| | - Maria A Aronova
- Laboratory of Cellular Imaging and Macromolecular Biophysics, National Institute of Biomedical Imaging and Bioengineering, National Institutes of Health, 9000 Rockville Pike, Bethesda, MD, USA
| | - Guofeng Zhang
- Laboratory of Cellular Imaging and Macromolecular Biophysics, National Institute of Biomedical Imaging and Bioengineering, National Institutes of Health, 9000 Rockville Pike, Bethesda, MD, USA
| | - Christine A Winters
- Laboratory of Neurobiology, National Institute of Neurological Disorders and Stroke, National Institutes of Health, 49 Convent Drive, Bethesda, MD, 20892, USA
| | - Thomas S Reese
- Laboratory of Neurobiology, National Institute of Neurological Disorders and Stroke, National Institutes of Health, 49 Convent Drive, Bethesda, MD, 20892, USA
| | - Carolyn L Smith
- Light Imaging Facility, National Institute of Neurological Disorders and Stroke, National Institutes of Health, 35 Convent Drive, Bethesda, MD, 20892, USA
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14
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Paganos P, Voronov D, Musser JM, Arendt D, Arnone MI. Single-cell RNA sequencing of the Strongylocentrotus purpuratus larva reveals the blueprint of major cell types and nervous system of a non-chordate deuterostome. eLife 2021; 10:70416. [PMID: 34821556 PMCID: PMC8683087 DOI: 10.7554/elife.70416] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2021] [Accepted: 11/24/2021] [Indexed: 12/15/2022] Open
Abstract
Identifying the molecular fingerprint of organismal cell types is key for understanding their function and evolution. Here, we use single-cell RNA sequencing (scRNA-seq) to survey the cell types of the sea urchin early pluteus larva, representing an important developmental transition from non-feeding to feeding larva. We identify 21 distinct cell clusters, representing cells of the digestive, skeletal, immune, and nervous systems. Further subclustering of these reveal a highly detailed portrait of cell diversity across the larva, including the identification of neuronal cell types. We then validate important gene regulatory networks driving sea urchin development and reveal new domains of activity within the larval body. Focusing on neurons that co-express Pdx-1 and Brn1/2/4, we identify an unprecedented number of genes shared by this population of neurons in sea urchin and vertebrate endocrine pancreatic cells. Using differential expression results from Pdx-1 knockdown experiments, we show that Pdx1 is necessary for the acquisition of the neuronal identity of these cells. We hypothesize that a network similar to the one orchestrated by Pdx1 in the sea urchin neurons was active in an ancestral cell type and then inherited by neuronal and pancreatic developmental lineages in sea urchins and vertebrates.
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Affiliation(s)
- Periklis Paganos
- Stazione Zoologica Anton Dohrn, Department of Biology and Evolution of Marine Organisms, Naples, Italy
| | - Danila Voronov
- Stazione Zoologica Anton Dohrn, Department of Biology and Evolution of Marine Organisms, Naples, Italy
| | - Jacob M Musser
- European Molecular Biology Laboratory, Developmental Biology Unit, Heidelberg, Germany
| | - Detlev Arendt
- European Molecular Biology Laboratory, Developmental Biology Unit, Heidelberg, Germany
| | - Maria Ina Arnone
- Stazione Zoologica Anton Dohrn, Department of Biology and Evolution of Marine Organisms, Naples, Italy
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15
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Musser JM, Schippers KJ, Nickel M, Mizzon G, Kohn AB, Pape C, Ronchi P, Papadopoulos N, Tarashansky AJ, Hammel JU, Wolf F, Liang C, Hernández-Plaza A, Cantalapiedra CP, Achim K, Schieber NL, Pan L, Ruperti F, Francis WR, Vargas S, Kling S, Renkert M, Polikarpov M, Bourenkov G, Feuda R, Gaspar I, Burkhardt P, Wang B, Bork P, Beck M, Schneider TR, Kreshuk A, Wörheide G, Huerta-Cepas J, Schwab Y, Moroz LL, Arendt D. Profiling cellular diversity in sponges informs animal cell type and nervous system evolution. Science 2021; 374:717-723. [PMID: 34735222 DOI: 10.1126/science.abj2949] [Citation(s) in RCA: 95] [Impact Index Per Article: 31.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
[Figure: see text].
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Affiliation(s)
- Jacob M Musser
- Developmental Biology Unit, European Molecular Biology Laboratory, 69117 Heidelberg, Germany
| | - Klaske J Schippers
- Developmental Biology Unit, European Molecular Biology Laboratory, 69117 Heidelberg, Germany
| | - Michael Nickel
- Developmental Biology Unit, European Molecular Biology Laboratory, 69117 Heidelberg, Germany.,Friedrich-Schiller-Universität Jena, Institut für Zoologie und Evolutionsforschung mit Phyletischem Museum, Ernst-Haeckel-Haus und Biologiedidaktik, 07743 Jena, Germany.,GeoBio-Center, Ludwig-Maximilians-Universität München, 80333 München, Germany
| | - Giulia Mizzon
- Electron Microscopy Core Facility, European Molecular Biology Laboratory, 69117 Heidelberg, Germany
| | - Andrea B Kohn
- Whitney Laboratory for Marine Bioscience, University of Florida, St. Augustine, FL 32080, USA
| | - Constantin Pape
- Cell Biology and Biophysics Unit, European Molecular Biology Laboratory, 69117 Heidelberg, Germany
| | - Paolo Ronchi
- Electron Microscopy Core Facility, European Molecular Biology Laboratory, 69117 Heidelberg, Germany
| | - Nikolaos Papadopoulos
- Developmental Biology Unit, European Molecular Biology Laboratory, 69117 Heidelberg, Germany
| | | | - Jörg U Hammel
- Friedrich-Schiller-Universität Jena, Institut für Zoologie und Evolutionsforschung mit Phyletischem Museum, Ernst-Haeckel-Haus und Biologiedidaktik, 07743 Jena, Germany.,Institute for Materials Physics, Helmholtz-Zentrum Hereon, 21502 Geesthacht, Germany
| | - Florian Wolf
- Friedrich-Schiller-Universität Jena, Institut für Zoologie und Evolutionsforschung mit Phyletischem Museum, Ernst-Haeckel-Haus und Biologiedidaktik, 07743 Jena, Germany
| | - Cong Liang
- Center for Applied Mathematics, Tianjin University, Tianjin 300072, China
| | - Ana Hernández-Plaza
- Centro de Biotecnología y Genómica de Plantas, Universidad Politécnica de Madrid (UPM) and Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA), 28223 Madrid, Spain
| | - Carlos P Cantalapiedra
- Centro de Biotecnología y Genómica de Plantas, Universidad Politécnica de Madrid (UPM) and Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA), 28223 Madrid, Spain
| | - Kaia Achim
- Developmental Biology Unit, European Molecular Biology Laboratory, 69117 Heidelberg, Germany
| | - Nicole L Schieber
- Cell Biology and Biophysics Unit, European Molecular Biology Laboratory, 69117 Heidelberg, Germany
| | - Leslie Pan
- Developmental Biology Unit, European Molecular Biology Laboratory, 69117 Heidelberg, Germany
| | - Fabian Ruperti
- Developmental Biology Unit, European Molecular Biology Laboratory, 69117 Heidelberg, Germany.,Collaboration for joint Ph.D. degree between EMBL and Heidelberg University, Faculty of Biosciences 69117 Heidelberg, Germany
| | - Warren R Francis
- Department of Earth and Environmental Sciences, Paleontology & Geobiology, Ludwig-Maximilians-Universität München, 80333 München, Germany
| | - Sergio Vargas
- Department of Earth and Environmental Sciences, Paleontology & Geobiology, Ludwig-Maximilians-Universität München, 80333 München, Germany
| | - Svenja Kling
- Developmental Biology Unit, European Molecular Biology Laboratory, 69117 Heidelberg, Germany.,Centre for Organismal Studies (COS), University of Heidelberg, 69120 Heidelberg, Germany
| | - Maike Renkert
- Developmental Biology Unit, European Molecular Biology Laboratory, 69117 Heidelberg, Germany
| | - Maxim Polikarpov
- Hamburg Unit c/o DESY, European Molecular Biology Laboratory, Hamburg, 22607 Germany.,Department of Information Technology and Electrical Engineering, ETH Zurich, CH-8092 Zurich, Switzerland
| | - Gleb Bourenkov
- Hamburg Unit c/o DESY, European Molecular Biology Laboratory, Hamburg, 22607 Germany
| | - Roberto Feuda
- Department of Genetics and Genome Biology, University of Leicester, Leicester LE1 7RH, UK
| | - Imre Gaspar
- Developmental Biology Unit, European Molecular Biology Laboratory, 69117 Heidelberg, Germany.,Department of Totipotency, Max Planck Institute of Biochemistry, 82152 Martinsried, Germany
| | - Pawel Burkhardt
- Sars International Centre for Marine Molecular Biology, University of Bergen, 5008 Bergen, Norway
| | - Bo Wang
- Department of Bioengineering, Stanford University, Stanford, CA 94305, USA.,Department of Developmental Biology, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Peer Bork
- Structural and Computational Biology Unit, European Molecular Biology Laboratory, 69117 Heidelberg, Germany
| | - Martin Beck
- Structural and Computational Biology Unit, European Molecular Biology Laboratory, 69117 Heidelberg, Germany
| | - Thomas R Schneider
- Hamburg Unit c/o DESY, European Molecular Biology Laboratory, Hamburg, 22607 Germany
| | - Anna Kreshuk
- Cell Biology and Biophysics Unit, European Molecular Biology Laboratory, 69117 Heidelberg, Germany
| | - Gert Wörheide
- GeoBio-Center, Ludwig-Maximilians-Universität München, 80333 München, Germany.,Department of Earth and Environmental Sciences, Paleontology & Geobiology, Ludwig-Maximilians-Universität München, 80333 München, Germany.,Bayerische Staatssammlung für Paläontologie und Geologie (SNSB), 80333 München, Germany
| | - Jaime Huerta-Cepas
- Centro de Biotecnología y Genómica de Plantas, Universidad Politécnica de Madrid (UPM) and Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA), 28223 Madrid, Spain.,Structural and Computational Biology Unit, European Molecular Biology Laboratory, 69117 Heidelberg, Germany
| | - Yannick Schwab
- Electron Microscopy Core Facility, European Molecular Biology Laboratory, 69117 Heidelberg, Germany.,Cell Biology and Biophysics Unit, European Molecular Biology Laboratory, 69117 Heidelberg, Germany
| | - Leonid L Moroz
- Whitney Laboratory for Marine Bioscience, University of Florida, St. Augustine, FL 32080, USA.,Department of Neuroscience and Brain Institute, University of Florida, Gainesville, FL 32610, USA.,McKnight Brain Institute, University of Florida, Gainesville, FL 32610, USA
| | - Detlev Arendt
- Developmental Biology Unit, European Molecular Biology Laboratory, 69117 Heidelberg, Germany.,Centre for Organismal Studies (COS), University of Heidelberg, 69120 Heidelberg, Germany
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16
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Abstract
Neurons are highly specialized cells equipped with a sophisticated molecular machinery for the reception, integration, conduction and distribution of information. The evolutionary origin of neurons remains unsolved. How did novel and pre-existing proteins assemble into the complex machinery of the synapse and of the apparatus conducting current along the neuron? In this review, the step-wise assembly of functional modules in neuron evolution serves as a paradigm for the emergence and modification of molecular machinery in the evolution of cell types in multicellular organisms. The pre-synaptic machinery emerged through modification of calcium-regulated large vesicle release, while the postsynaptic machinery has different origins: the glutamatergic postsynapse originated through the fusion of a sensory signaling module and a module for filopodial outgrowth, while the GABAergic postsynapse incorporated an ancient actin regulatory module. The synaptic junction, in turn, is built around two adhesion modules controlled by phosphorylation, which resemble septate and adherens junctions. Finally, neuronal action potentials emerged via a series of duplications and modifications of voltage-gated ion channels. Based on these origins, key molecular innovations are identified that led to the birth of the first neuron in animal evolution.
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17
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Fields C, Glazebrook JF, Levin M. Minimal physicalism as a scale-free substrate for cognition and consciousness. Neurosci Conscious 2021; 2021:niab013. [PMID: 34345441 PMCID: PMC8327199 DOI: 10.1093/nc/niab013] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2021] [Revised: 04/04/2021] [Accepted: 04/05/2021] [Indexed: 12/14/2022] Open
Abstract
Theories of consciousness and cognition that assume a neural substrate automatically regard phylogenetically basal, nonneural systems as nonconscious and noncognitive. Here, we advance a scale-free characterization of consciousness and cognition that regards basal systems, including synthetic constructs, as not only informative about the structure and function of experience in more complex systems but also as offering distinct advantages for experimental manipulation. Our "minimal physicalist" approach makes no assumptions beyond those of quantum information theory, and hence is applicable from the molecular scale upwards. We show that standard concepts including integrated information, state broadcasting via small-world networks, and hierarchical Bayesian inference emerge naturally in this setting, and that common phenomena including stigmergic memory, perceptual coarse-graining, and attention switching follow directly from the thermodynamic requirements of classical computation. We show that the self-representation that lies at the heart of human autonoetic awareness can be traced as far back as, and serves the same basic functions as, the stress response in bacteria and other basal systems.
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Affiliation(s)
- Chris Fields
- 23 Rue des Lavandières, 11160 Caunes Minervois, France
| | - James F Glazebrook
- Department of Mathematics and Computer Science, Eastern Illinois University, 600 Lincoln Ave, Charleston, IL 61920 USA
- Department of Mathematics, Adjunct Faculty, University of Illinois at Urbana–Champaign, 1409 W. Green Street, Urbana, IL 61801, USA
| | - Michael Levin
- Allen Discovery Center, Tufts University, 200 College Avenue, Medford, MA 02155, USA
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18
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Aboitiz F, Montiel JF. The Enigmatic Reissner's Fiber and the Origin of Chordates. Front Neuroanat 2021; 15:703835. [PMID: 34248511 PMCID: PMC8261243 DOI: 10.3389/fnana.2021.703835] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2021] [Accepted: 06/03/2021] [Indexed: 12/02/2022] Open
Abstract
Reissner’s fiber (RF) is a secreted filament that floats in the neural canal of chordates. Since its discovery in 1860, there has been no agreement on its primary function, and its strong conservation across chordate species has remained a mystery for comparative neuroanatomists. Several findings, including the chemical composition and the phylogenetic history of RF, clinical observations associating RF with the development of the neural canal, and more recent studies suggesting that RF is needed to develop a straight vertebral column, may shed light on the functions of this structure across chordates. In this article, we will briefly review the evidence mentioned above to suggest a role of RF in the origin of fundamental innovations of the chordate body plan, especially the elongation of the neural tube and maintenance of the body axis. We will also mention the relevance of RF for medical conditions like hydrocephalus, scoliosis of the vertebral spine and possibly regeneration of the spinal cord.
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Affiliation(s)
- Francisco Aboitiz
- Departamento de Psiquiatría, Escuela de Medicina, Pontificia Universidad Católica de Chile, Santiago, Chile.,Centro Interdisciplinario de Neurociencias, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Juan F Montiel
- Centro de Investigación Biomédica, Facultad de Medicina, Universidad Diego Portales, Santiago, Chile
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19
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Göhde R, Naumann B, Laundon D, Imig C, McDonald K, Cooper BH, Varoqueaux F, Fasshauer D, Burkhardt P. Choanoflagellates and the ancestry of neurosecretory vesicles. Philos Trans R Soc Lond B Biol Sci 2021; 376:20190759. [PMID: 33550951 PMCID: PMC7934909 DOI: 10.1098/rstb.2019.0759] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/26/2020] [Indexed: 01/08/2023] Open
Abstract
Neurosecretory vesicles are highly specialized trafficking organelles that store neurotransmitters that are released at presynaptic nerve endings and are, therefore, important for animal cell-cell signalling. Despite considerable anatomical and functional diversity of neurons in animals, the protein composition of neurosecretory vesicles in bilaterians appears to be similar. This similarity points towards a common evolutionary origin. Moreover, many putative homologues of key neurosecretory vesicle proteins predate the origin of the first neurons, and some even the origin of the first animals. However, little is known about the molecular toolkit of these vesicles in non-bilaterian animals and their closest unicellular relatives, making inferences about the evolutionary origin of neurosecretory vesicles extremely difficult. By comparing 28 proteins of the core neurosecretory vesicle proteome in 13 different species, we demonstrate that most of the proteins are present in unicellular organisms. Surprisingly, we find that the vesicular membrane-associated soluble N-ethylmaleimide-sensitive factor attachment protein receptor protein synaptobrevin is localized to the vesicle-rich apical and basal pole in the choanoflagellate Salpingoeca rosetta. Our 3D vesicle reconstructions reveal that the choanoflagellates S. rosetta and Monosiga brevicollis exhibit a polarized and diverse vesicular landscape reminiscent of the polarized organization of chemical synapses that secrete the content of neurosecretory vesicles into the synaptic cleft. This study sheds light on the ancestral molecular machinery of neurosecretory vesicles and provides a framework to understand the origin and evolution of secretory cells, synapses and neurons. This article is part of the theme issue 'Basal cognition: multicellularity, neurons and the cognitive lens'.
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Affiliation(s)
- Ronja Göhde
- Sars International Centre for Molecular Marine Biology, University of Bergen, 5006 Bergen, Norway
| | - Benjamin Naumann
- Institute of Zoology and Evolutionary Research, Friedrich Schiller University Jena, 07743 Jena, Germany
| | - Davis Laundon
- Marine Biological Association of the United Kingdom, The Laboratory, Citadel Hill, Plymouth PL1 2PB, UK
| | - Cordelia Imig
- Department of Molecular Neurobiology, Max Planck Institute of Experimental Medicine, 37075 Gottingen, Germany
| | - Kent McDonald
- Electron Microscope Laboratory, University of California, Berkeley, CA 94720, USA
| | - Benjamin H. Cooper
- Department of Molecular Neurobiology, Max Planck Institute of Experimental Medicine, 37075 Gottingen, Germany
| | - Frédérique Varoqueaux
- Department of Fundamental Neurosciences, University of Lausanne, 1005 Lausanne, Switzerland
| | - Dirk Fasshauer
- Department of Fundamental Neurosciences, University of Lausanne, 1005 Lausanne, Switzerland
| | - Pawel Burkhardt
- Sars International Centre for Molecular Marine Biology, University of Bergen, 5006 Bergen, Norway
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20
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Abstract
The evolutionary origin of the nervous system has been a matter of long-standing debate. This is due to the different perspectives taken. Earlier studies addressed nervous system origins at the cellular level. They focused on the selective advantage of the first neuron in its local context, and considered vertical sensory-motor reflex arcs the first nervous system. Later studies emphasized the value of the nervous system at the tissue level. Rather than acting locally, early neurons were seen as part of an elementary nerve net that enabled the horizontal coordination of tissue movements. Opinions have also differed on the nature of effector cells. While most authors have favoured contractile systems, others see the key output of the incipient nervous system in the coordination of motile cilia, or the secretion of antimicrobial peptides. I will discuss these divergent views and explore how they can be validated by molecular and single-cell data. From this survey, possible consensus emerges: (i) the first manifestation of the nervous system likely was a nerve net, whereas specialized local circuits evolved later; (ii) different nerve nets may have evolved for the coordination of contractile or cilia-driven movements; (iii) all evolving nerve nets facilitated new forms of animal behaviour with increasing body size. This article is part of the theme issue 'Basal cognition: multicellularity, neurons and the cognitive lens'.
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Affiliation(s)
- Detlev Arendt
- Developmental Biology Unit, European Molecular Biology Laboratory, Heidelberg, Germany
- Centre for Organismal Studies, University of Heidelberg, Heidelberg, Germany
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21
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Brunet T, Albert M, Roman W, Coyle MC, Spitzer DC, King N. A flagellate-to-amoeboid switch in the closest living relatives of animals. eLife 2021; 10:e61037. [PMID: 33448265 PMCID: PMC7895527 DOI: 10.7554/elife.61037] [Citation(s) in RCA: 37] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2020] [Accepted: 01/14/2021] [Indexed: 12/19/2022] Open
Abstract
Amoeboid cell types are fundamental to animal biology and broadly distributed across animal diversity, but their evolutionary origin is unclear. The closest living relatives of animals, the choanoflagellates, display a polarized cell architecture (with an apical flagellum encircled by microvilli) that resembles that of epithelial cells and suggests homology, but this architecture differs strikingly from the deformable phenotype of animal amoeboid cells, which instead evoke more distantly related eukaryotes, such as diverse amoebae. Here, we show that choanoflagellates subjected to confinement become amoeboid by retracting their flagella and activating myosin-based motility. This switch allows escape from confinement and is conserved across choanoflagellate diversity. The conservation of the amoeboid cell phenotype across animals and choanoflagellates, together with the conserved role of myosin, is consistent with homology of amoeboid motility in both lineages. We hypothesize that the differentiation between animal epithelial and crawling cells might have evolved from a stress-induced switch between flagellate and amoeboid forms in their single-celled ancestors.
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Affiliation(s)
- Thibaut Brunet
- Howard Hughes Medical InstituteChevy ChaseUnited States
- Department of Molecular and Cell Biology, University of California, BerkeleyBerkeleyUnited States
| | - Marvin Albert
- Department of Molecular Life Sciences, University of ZürichZurichSwitzerland
| | - William Roman
- Department of Experimental and Health Sciences, Pompeu Fabra University (UPF), CIBERNEDBarcelonaSpain
| | - Maxwell C Coyle
- Howard Hughes Medical InstituteChevy ChaseUnited States
- Department of Molecular and Cell Biology, University of California, BerkeleyBerkeleyUnited States
| | - Danielle C Spitzer
- Department of Molecular and Cell Biology, University of California, BerkeleyBerkeleyUnited States
| | - Nicole King
- Howard Hughes Medical InstituteChevy ChaseUnited States
- Department of Molecular and Cell Biology, University of California, BerkeleyBerkeleyUnited States
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22
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Brunet T, Larson BT, Linden TA, Vermeij MJA, McDonald K, King N. Light-regulated collective contractility in a multicellular choanoflagellate. Science 2020; 366:326-334. [PMID: 31624206 DOI: 10.1126/science.aay2346] [Citation(s) in RCA: 74] [Impact Index Per Article: 18.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2019] [Accepted: 09/16/2019] [Indexed: 12/11/2022]
Abstract
Collective cell contractions that generate global tissue deformations are a signature feature of animal movement and morphogenesis. However, the origin of collective contractility in animals remains unclear. While surveying the Caribbean island of Curaçao for choanoflagellates, the closest living relatives of animals, we isolated a previously undescribed species (here named Choanoeca flexa sp. nov.) that forms multicellular cup-shaped colonies. The colonies rapidly invert their curvature in response to changing light levels, which they detect through a rhodopsin-cyclic guanosine monophosphate pathway. Inversion requires actomyosin-mediated apical contractility and allows alternation between feeding and swimming behavior. C. flexa thus rapidly converts sensory inputs directly into multicellular contractions. These findings may inform reconstructions of hypothesized animal ancestors that existed before the evolution of specialized sensory and contractile cells.
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Affiliation(s)
- Thibaut Brunet
- Howard Hughes Medical Institute and the Department of Molecular and Cell Biology, University of California, Berkeley, CA, USA
| | - Ben T Larson
- Howard Hughes Medical Institute and the Department of Molecular and Cell Biology, University of California, Berkeley, CA, USA.,Biophysics Graduate Group, University of California, Berkeley, CA, USA
| | - Tess A Linden
- Howard Hughes Medical Institute and the Department of Molecular and Cell Biology, University of California, Berkeley, CA, USA
| | - Mark J A Vermeij
- Department of Aquatic Microbiology, Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, CARMABI, Piscaderabaai z/n Willemstad, Curaçao
| | - Kent McDonald
- Electron Microscopy Laboratory, University of California, Berkeley, CA, USA
| | - Nicole King
- Howard Hughes Medical Institute and the Department of Molecular and Cell Biology, University of California, Berkeley, CA, USA.
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23
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Malakhov VV, Bogomolova EV, Kuzmina TV, Temereva EN. Evolution of Metazoan Life Cycles and the Origin of Pelagic Larvae. Russ J Dev Biol 2020. [DOI: 10.1134/s1062360419060043] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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24
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Fields C, Levin M. Does regeneration recapitulate phylogeny? Planaria as a model of body-axis specification in ancestral eumetazoa. Commun Integr Biol 2020; 13:27-38. [PMID: 32128026 PMCID: PMC7039665 DOI: 10.1080/19420889.2020.1729601] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2019] [Revised: 02/07/2020] [Accepted: 02/09/2020] [Indexed: 12/31/2022] Open
Abstract
Metazoan body plans combine well-defined primary, secondary, and in many bilaterians, tertiary body axes with structural asymmetries at multiple scales. Despite decades of study, how axis-defining symmetries and system-defining asymmetries co-emerge during both evolution and development remain open questions. Regeneration studies in asexual planaria have demonstrated an array of viable forms with symmetrized and, in some cases, duplicated body axes. We suggest that such forms may point toward an ancestral eumetazoan form with characteristics of both cnidarians and placazoa.
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Affiliation(s)
| | - Michael Levin
- Allen Discovery Center, Tufts University, Medford, MA, USA
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25
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Bezares-Calderón LA, Berger J, Jékely G. Diversity of cilia-based mechanosensory systems and their functions in marine animal behaviour. Philos Trans R Soc Lond B Biol Sci 2020; 375:20190376. [PMID: 31884914 PMCID: PMC7017336 DOI: 10.1098/rstb.2019.0376] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/03/2019] [Indexed: 12/12/2022] Open
Abstract
Sensory cells that detect mechanical forces usually have one or more specialized cilia. These mechanosensory cells underlie hearing, proprioception or gravity sensation. To date, it is unclear how cilia contribute to detecting mechanical forces and what is the relationship between mechanosensory ciliated cells in different animal groups and sensory systems. Here, we review examples of ciliated sensory cells with a focus on marine invertebrate animals. We discuss how various ciliated cells mediate mechanosensory responses during feeding, tactic responses or predator-prey interactions. We also highlight some of these systems as interesting and accessible models for future in-depth behavioural, functional and molecular studies. We envisage that embracing a broader diversity of organisms could lead to a more complete view of cilia-based mechanosensation. This article is part of the Theo Murphy meeting issue 'Unity and diversity of cilia in locomotion and transport'.
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Affiliation(s)
| | - Jürgen Berger
- Max Planck Institute for Developmental Biology, 72076 Tübingen, Germany
| | - Gáspár Jékely
- Living Systems Institute, University of Exeter, Stocker Road, Exeter EX4 4QD, UK
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26
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Fields C, Bischof J, Levin M. Morphological Coordination: A Common Ancestral Function Unifying Neural and Non-Neural Signaling. Physiology (Bethesda) 2020; 35:16-30. [DOI: 10.1152/physiol.00027.2019] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Nervous systems are traditionally thought of as providing sensing and behavioral coordination functions at the level of the whole organism. What is the evolutionary origin of the mechanisms enabling the nervous systems’ information processing ability? Here, we review evidence from evolutionary, developmental, and regenerative biology suggesting a deeper, ancestral function of both pre-neural and neural cell-cell communication systems: the long-distance coordination of cell division and differentiation required to create and maintain body-axis symmetries. This conceptualization of the function of nervous system activity sheds new light on the evolutionary transition from the morphologically rudimentary, non-neural Porifera and Placazoa to the complex morphologies of Ctenophores, Cnidarians, and Bilaterians. It further allows a sharp formulation of the distinction between long-distance axis-symmetry coordination based on external coordinates, e.g., by whole-organism scale trophisms as employed by plants and sessile animals, and coordination based on body-centered coordinates as employed by motile animals. Thus we suggest that the systems that control animal behavior evolved from ancient mechanisms adapting preexisting ionic and neurotransmitter mechanisms to regulate individual cell behaviors during morphogenesis. An appreciation of the ancient, non-neural origins of bioelectrically mediated computation suggests new approaches to the study of embryological development, including embryological dysregulation, cancer, regenerative medicine, and synthetic bioengineering.
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Affiliation(s)
- Chris Fields
- 23 Rue des Lavandières, Caunes Minervois, France
| | - Johanna Bischof
- Allen Discovery Center at Tufts University, Medford, Massachusetts
| | - Michael Levin
- Allen Discovery Center at Tufts University, Medford, Massachusetts
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27
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Powell R, O'Malley MA. Metabolic and microbial perspectives on the "evolution of evolution". JOURNAL OF EXPERIMENTAL ZOOLOGY. PART B, MOLECULAR AND DEVELOPMENTAL EVOLUTION 2019; 332:321-330. [PMID: 31532063 DOI: 10.1002/jez.b.22898] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/01/2019] [Revised: 07/20/2019] [Accepted: 07/23/2019] [Indexed: 06/10/2023]
Abstract
Identifying and theorizing major turning points in the history of life generates insights into not only world-changing evolutionary events but also the processes that bring these events about. In his treatment of these issues, Bonner identifies the evolution of sex, multicellularity, and nervous systems as enabling the "evolution of evolution," which involves fundamental transformations in how evolution occurs. By contextualizing his framework within two decades of theorizing about major transitions in evolution, we identify some basic problems that Bonner's theory shares with much of the prevailing literature. These problems include implicit progressivism, theoretical disunity, and a limited ability to explain major evolutionary transformations. We go on to identify events and processes that are neglected by existing views. In contrast with the "vertical" focus on replication, hierarchy, and morphology that preoccupies most of the literature on major transitions, we propose a "horizontal" dimension in which metabolism and microbial innovations play a central explanatory role in understanding the broad-scale organization of life.
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Affiliation(s)
- Russell Powell
- Department of Philosophy, Boston University, Boston, Massachusetts
| | - Maureen A O'Malley
- School of History and Philosophy of Science, University of Bordeaux/University of Sydney, Sydney, Australia
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28
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Arnellos A, Keijzer F. Bodily Complexity: Integrated Multicellular Organizations for Contraction-Based Motility. Front Physiol 2019; 10:1268. [PMID: 31680996 PMCID: PMC6803425 DOI: 10.3389/fphys.2019.01268] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2019] [Accepted: 09/19/2019] [Indexed: 01/13/2023] Open
Abstract
Compared to other forms of multicellularity, the animal case is unique. Animals-barring some exceptions-consist of collections of cells that are connected and integrated to such an extent that these collectives act as unitary, large free-moving entities capable of sensing macroscopic properties and events. This animal configuration is so well-known that it is often taken as a natural one that 'must' have evolved, given environmental conditions that make large free-moving units 'obviously' adaptive. Here we question the seemingly evolutionary inevitableness of animals and introduce a thesis of bodily complexity: The multicellular organization characteristic for typical animals requires the integration of a multitude of intrinsic bodily features between its sensorimotor, physiological, and developmental aspects, and the related contraction-based tissue- and cellular-level events and processes. The evolutionary road toward this bodily complexity involves, we argue, various intermediate organizational steps that accompany and support the wider transition from cilia-based to contraction/muscle-based motility, and which remain insufficiently acknowledged. Here, we stress the crucial and specific role played by muscle-based and myoepithelial tissue contraction-acting as a physical platform for organizing both the multicellular transmission of mechanical forces and multicellular signaling-as key foundation of animal motility, sensing and maintenance, and development. We illustrate and discuss these bodily features in the context of the four basal animal phyla-Porifera, Ctenophores, Placozoans, and Cnidarians-that split off before the bilaterians, a supergroup that incorporates all complex animals.
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Affiliation(s)
- Argyris Arnellos
- IAS-Research Centre for Life, Mind & Society, Department of Logic and Philosophy of Science, University of the Basque Country, San Sebastián, Spain.,Department of Product and Systems Design Engineering, Complex Systems and Service Design Lab, University of the Aegean, Syros, Greece
| | - Fred Keijzer
- Department of Theoretical Philosophy, University of Groningen, Groningen, Netherlands
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Paulin MG, Cahill‐Lane J. Events in Early Nervous System Evolution. Top Cogn Sci 2019; 13:25-44. [DOI: 10.1111/tops.12461] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2019] [Revised: 09/09/2019] [Accepted: 09/09/2019] [Indexed: 12/20/2022]
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30
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Driever W. Developmental Biology: Reissner's Fiber and Straightening of the Body Axis. Curr Biol 2019; 28:R833-R835. [PMID: 30086316 DOI: 10.1016/j.cub.2018.05.080] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Abstract
A straight longitudinal body axis supports efficient directed locomotion of fish and other vertebrates. New research demonstrates that Reissner's fiber, an enigmatic structure within the spinal central canal, is essential for development of an extended trunk to tail axis.
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Affiliation(s)
- Wolfgang Driever
- Developmental Biology, Institute of Biology I, and BIOSS, Albert Ludwig University Freiburg, 79104 Freiburg, Germany.
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31
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Steinmetz PRH. A non-bilaterian perspective on the development and evolution of animal digestive systems. Cell Tissue Res 2019; 377:321-339. [PMID: 31388768 PMCID: PMC6733828 DOI: 10.1007/s00441-019-03075-x] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2019] [Accepted: 07/08/2019] [Indexed: 12/14/2022]
Abstract
Digestive systems and extracellular digestion are key animal features, but their emergence during early animal evolution is currently poorly understood. As the last common ancestor of non-bilaterian animal groups (sponges, ctenophores, placozoans and cnidarians) dates back to the beginning of animal life, their study and comparison provides important insights into the early evolution of digestive systems and functions. Here, I have compiled an overview of the development and cell biology of digestive tissues in non-bilaterian animals. I will highlight the fundamental differences between extracellular and intracellular digestive processes, and how these are distributed among animals. Cnidarians (e.g. sea anemones, corals, jellyfish), the phylogenetic outgroup of bilaterians (e.g. vertebrates, flies, annelids), occupy a key position to reconstruct the evolution of bilaterian gut evolution. A major focus will therefore lie on the development and cell biology of digestive tissues in cnidarians, especially sea anemones, and how they compare to bilaterian gut tissues. In that context, I will also review how a recent study on the gastrula fate map of the sea anemone Nematostella vectensis challenges our long-standing conceptions on the evolution of cnidarian and bilaterian germ layers and guts.
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Affiliation(s)
- Patrick R H Steinmetz
- Sars International Centre for Marine Molecular Biology, University of Bergen, Thormøhlensgt. 55, 5006, Bergen, Norway.
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32
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Mayorova TD, Hammar K, Winters CA, Reese TS, Smith CL. The ventral epithelium of Trichoplax adhaerens deploys in distinct patterns cells that secrete digestive enzymes, mucus or diverse neuropeptides. Biol Open 2019; 8:bio045674. [PMID: 31366453 PMCID: PMC6737977 DOI: 10.1242/bio.045674] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2019] [Accepted: 07/23/2019] [Indexed: 01/11/2023] Open
Abstract
The disk-shaped millimeter-sized marine animal, Trichoplax adhaerens, is notable because of its small number of cell types and primitive mode of feeding. It glides on substrates propelled by beating cilia on its lower surface and periodically pauses to feed on underlying microorganisms, which it digests externally. Here, a combination of advanced electron and light microscopic techniques are used to take a closer look at its secretory cell types and their roles in locomotion and feeding. We identify digestive enzymes in lipophils, a cell type implicated in external digestion and distributed uniformly throughout the ventral epithelium except for a narrow zone near its edge. We find three morphologically distinct types of gland cell. The most prevalent contains and secretes mucus, which is shown to be involved in adhesion and gliding. Half of the mucocytes are arrayed in a tight row around the edge of the ventral epithelium while the rest are scattered further inside, in the region containing lipophils. The secretory granules in mucocytes at the edge label with an antibody against a neuropeptide that was reported to arrest ciliary beating during feeding. A second type of gland cell is arrayed in a narrow row just inside the row of mucocytes while a third is located more centrally. Our maps of the positions of the structurally distinct secretory cell types provide a foundation for further characterization of the multiple peptidergic cell types in Trichoplax and the microscopic techniques we introduce provide tools for carrying out these studies.
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Affiliation(s)
- Tatiana D Mayorova
- Laboratory of Neurobiology, National Institute of Neurological Disorders and Stroke, National Institutes of Health, 49 Convent Drive, Bethesda, MD 20892, USA
| | - Katherine Hammar
- Central Microscopy Facility, Marine Biological Laboratory, 7 MBL Street, Woods Hole, MA 02543, USA
| | - Christine A Winters
- Laboratory of Neurobiology, National Institute of Neurological Disorders and Stroke, National Institutes of Health, 49 Convent Drive, Bethesda, MD 20892, USA
| | - Thomas S Reese
- Laboratory of Neurobiology, National Institute of Neurological Disorders and Stroke, National Institutes of Health, 49 Convent Drive, Bethesda, MD 20892, USA
| | - Carolyn L Smith
- Light Imaging Facility, National Institute of Neurological Disorders and Stroke, National Institutes of Health, 35 Convent Drive, Bethesda, MD 20892, USA
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Smith CL, Mayorova TD. Insights into the evolution of digestive systems from studies of Trichoplax adhaerens. Cell Tissue Res 2019; 377:353-367. [PMID: 31270610 DOI: 10.1007/s00441-019-03057-z] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2019] [Accepted: 06/09/2019] [Indexed: 01/01/2023]
Abstract
Trichoplax, a member of the phylum Placozoa, is a tiny ciliated marine animal that glides on surfaces feeding on algae and cyanobacteria. It stands out from other animals in that it lacks an internal digestive system and, instead, digests food trapped under its lower surface. Here we review recent work on the phenotypes of its six cell types and their roles in digestion and feeding behavior. Phylogenomic analyses place Placozoa as sister to Eumetazoa, the clade that includes Cnidaria and Bilateria. Comparing the phenotypes of cells in Trichoplax to those of cells in the digestive epithelia of Eumetazoa allows us to make inferences about the cell types and mode of feeding of their ancestors. From our increasingly mechanistic understanding of feeding in Trichoplax, we get a glimpse into how primitive animals may have hunted and consumed food prior to the evolution of neurons, muscles, and internal digestive systems.
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Affiliation(s)
- Carolyn L Smith
- National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, 20892, USA.
| | - Tatiana D Mayorova
- National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, 20892, USA
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34
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Nielsen C. Early animal evolution: a morphologist's view. ROYAL SOCIETY OPEN SCIENCE 2019; 6:190638. [PMID: 31417759 PMCID: PMC6689584 DOI: 10.1098/rsos.190638] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/05/2019] [Accepted: 07/04/2019] [Indexed: 05/15/2023]
Abstract
Two hypotheses for the early radiation of the metazoans are vividly discussed in recent phylogenomic studies, the 'Porifera-first' hypothesis, which places the poriferans as the sister group of all other metazoans, and the 'Ctenophora-first' hypothesis, which places the ctenophores as the sister group to all other metazoans. It has been suggested that an analysis of morphological characters (including specific molecules) could throw additional light on the controversy, and this is the aim of this paper. Both hypotheses imply independent evolution of nervous systems in Planulozoa and Ctenophora. The Porifera-first hypothesis implies no homoplasies or losses of major characters. The Ctenophora-first hypothesis shows no important synapomorphies of Porifera, Planulozoa and Placozoa. It implies either independent evolution, in Planulozoa and Ctenophora, of a new digestive system with a gut with extracellular digestion, which enables feeding on larger organisms, or the subsequent loss of this new gut in the Poriferans (and the re-evolution of the collar complex). The major losses implied in the Ctenophora-first theory show absolutely no adaptational advantages. Thus, morphology gives very strong support for the Porifera-first hypothesis.
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Affiliation(s)
- Claus Nielsen
- The Natural History Museum of Denmark, University of Copenhagen, Zoological Museum, Universitetsparken 15, DK-2100 Copenhagen, Denmark
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35
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Pluripotency and the origin of animal multicellularity. Nature 2019; 570:519-522. [PMID: 31189954 DOI: 10.1038/s41586-019-1290-4] [Citation(s) in RCA: 74] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2017] [Accepted: 05/16/2019] [Indexed: 01/01/2023]
Abstract
A widely held-but rarely tested-hypothesis for the origin of animals is that they evolved from a unicellular ancestor, with an apical cilium surrounded by a microvillar collar, that structurally resembled modern sponge choanocytes and choanoflagellates1-4. Here we test this view of animal origins by comparing the transcriptomes, fates and behaviours of the three primary sponge cell types-choanocytes, pluripotent mesenchymal archaeocytes and epithelial pinacocytes-with choanoflagellates and other unicellular holozoans. Unexpectedly, we find that the transcriptome of sponge choanocytes is the least similar to the transcriptomes of choanoflagellates and is significantly enriched in genes unique to either animals or sponges alone. By contrast, pluripotent archaeocytes upregulate genes that control cell proliferation and gene expression, as in other metazoan stem cells and in the proliferating stages of two unicellular holozoans, including a colonial choanoflagellate. Choanocytes in the sponge Amphimedon queenslandica exist in a transient metastable state and readily transdifferentiate into archaeocytes, which can differentiate into a range of other cell types. These sponge cell-type conversions are similar to the temporal cell-state changes that occur in unicellular holozoans5. Together, these analyses argue against homology of sponge choanocytes and choanoflagellates, and the view that the first multicellular animals were simple balls of cells with limited capacity to differentiate. Instead, our results are consistent with the first animal cell being able to transition between multiple states in a manner similar to modern transdifferentiating and stem cells.
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36
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Coherent directed movement toward food modeled in Trichoplax, a ciliated animal lacking a nervous system. Proc Natl Acad Sci U S A 2019; 116:8901-8908. [PMID: 30979806 PMCID: PMC6500112 DOI: 10.1073/pnas.1815655116] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Trichoplax adhaerens is a small, ciliated marine animal that glides on surfaces grazing upon algae, which it digests externally. It has no muscles or nervous system and only six cell types, all but two of which are embedded in its epithelium. The epithelial cells are joined by apical adherens junctions; neither tight junctions nor gap junctions are present. Monociliated epithelial cells on the lower surface propel gliding. The cilia beat regularly, but asynchronously, and transiently contact the substrate with each stroke. The animal moves in random directions in the absence of food. We show here that it exhibits chemotaxis, moving preferentially toward algae embedded in a disk of agar. We present a mathematical model to explain how coherent, directional movements could arise from the collective actions of a set of ciliated epithelial cells, each independently sensing and responding to a chemoattractant gradient. The model incorporates realistic values for viscoelastic properties of cells and produces coordinated movements and changes in body shape that resemble the actual movements of the animal. The model demonstrates that an animal can move coherently in search of food without any need for chemical signaling between cells and introduces a different approach to modeling behavior in primitive multicellular organisms.
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37
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Arendt D, Bertucci PY, Achim K, Musser JM. Evolution of neuronal types and families. Curr Opin Neurobiol 2019; 56:144-152. [PMID: 30826503 PMCID: PMC6556553 DOI: 10.1016/j.conb.2019.01.022] [Citation(s) in RCA: 63] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2019] [Revised: 01/25/2019] [Accepted: 01/27/2019] [Indexed: 12/12/2022]
Abstract
Solving nervous system evolution requires cross-species comparison of neuronal types. Neuronal types are commonly defined by their specific structure and function. We provide an operational definition of cell types that allows evolutionary comparison. The identity of neuronal types is best reflected by specifying transcription factors. Families of related neuronal types are conserved across large evolutionary distances.
Major questions in the evolution of neurons and nervous systems remain unsolved, such as the origin of the first neuron, the possible convergent evolution of neuronal phenotypes, and the transition from a relatively simple decentralized nerve net to the complex, centralized nervous systems found in modern bilaterian animals. In recent years, comparative single-cell transcriptomics has opened up new research avenues addressing these issues. Here, we review recent conceptual progress toward an evolutionary definition of cell types, and how it facilitates the identification and large-scale comparison of neuronal types and neuron type families from single-cell data — with the family of GABAergic neurons in distinct parts of the vertebrate forebrain as prime example. We also highlight strategies to infer cell type-specific innovation, so-called apomeres, from single-cell data.
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Affiliation(s)
- Detlev Arendt
- Developmental Biology Unit, European Molecular Biology Laboratory, Meyerhofstrasse 1, 69012, Heidelberg, Germany.
| | - Paola Yanina Bertucci
- Developmental Biology Unit, European Molecular Biology Laboratory, Meyerhofstrasse 1, 69012, Heidelberg, Germany
| | - Kaia Achim
- Developmental Biology Unit, European Molecular Biology Laboratory, Meyerhofstrasse 1, 69012, Heidelberg, Germany
| | - Jacob M Musser
- Developmental Biology Unit, European Molecular Biology Laboratory, Meyerhofstrasse 1, 69012, Heidelberg, Germany
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38
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Dufour SC, McIlroy D. An Ediacaran pre-placozoan alternative to the pre-sponge route towards the Cambrian explosion of animal life: a comment on Cavalier-Smith 2017. Philos Trans R Soc Lond B Biol Sci 2019; 373:rstb.2017.0148. [PMID: 29203719 DOI: 10.1098/rstb.2017.0148] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/11/2017] [Indexed: 01/09/2023] Open
Affiliation(s)
- Suzanne C Dufour
- Department of Biology, Memorial University of Newfoundland, St John's, Newfoundland and Labrador, Canada A1B 3X9
| | - Duncan McIlroy
- Department of Earth Sciences, Memorial University of Newfoundland, St John's, Newfoundland and Labrador, Canada A1B 3X5
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39
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High Cell Diversity and Complex Peptidergic Signaling Underlie Placozoan Behavior. Curr Biol 2018; 28:3495-3501.e2. [DOI: 10.1016/j.cub.2018.08.067] [Citation(s) in RCA: 66] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2018] [Revised: 07/20/2018] [Accepted: 08/31/2018] [Indexed: 12/17/2022]
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40
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41
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Evolution of the bilaterian mouth and anus. Nat Ecol Evol 2018; 2:1358-1376. [PMID: 30135501 DOI: 10.1038/s41559-018-0641-0] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2017] [Revised: 06/26/2018] [Accepted: 07/11/2018] [Indexed: 12/17/2022]
Abstract
It is widely held that the bilaterian tubular gut with mouth and anus evolved from a simple gut with one major gastric opening. However, there is no consensus on how this happened. Did the single gastric opening evolve into a mouth, with the anus forming elsewhere in the body (protostomy), or did it evolve into an anus, with the mouth forming elsewhere (deuterostomy), or did it evolve into both mouth and anus (amphistomy)? These questions are addressed by the comparison of developmental fates of the blastopore, the opening of the embryonic gut, in diverse animals that live today. Here we review comparative data on the identity and fate of blastoporal tissue, investigate how the formation of the through-gut relates to the major body axes, and discuss to what extent evolutionary scenarios are consistent with these data. Available evidence indicates that stem bilaterians had a slit-like gastric opening that was partially closed in subsequent evolution, leaving open the anus and most likely also the mouth, which would favour amphistomy. We discuss remaining difficulties, and outline directions for future research.
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42
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Whole-organism cellular gene-expression atlas reveals conserved cell types in the ventral nerve cord of Platynereis dumerilii. Proc Natl Acad Sci U S A 2018; 114:5878-5885. [PMID: 28584082 DOI: 10.1073/pnas.1610602114] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
The comparative study of cell types is a powerful approach toward deciphering animal evolution. To avoid selection biases, however, comparisons ideally involve all cell types present in a multicellular organism. Here, we use image registration and a newly developed "Profiling by Signal Probability Mapping" algorithm to generate a cellular resolution 3D expression atlas for an entire animal. We investigate three-segmented young worms of the marine annelid Platynereis dumerilii, with a rich diversity of differentiated cells present in relatively low number. Starting from whole-mount expression images for close to 100 neural specification and differentiation genes, our atlas identifies and molecularly characterizes 605 bilateral pairs of neurons at specific locations in the ventral nerve cord. Among these pairs, we identify sets of neurons expressing similar combinations of transcription factors, located at spatially coherent anterior-posterior, dorsal-ventral, and medial-lateral coordinates that we interpret as cell types. Comparison with motor and interneuron types in the vertebrate neural tube indicates conserved combinations, for example, of cell types cospecified by Gata1/2/3 and Tal transcription factors. These include V2b interneurons and the central spinal fluid-contacting Kolmer-Agduhr cells in the vertebrates, and several neuron types in the intermediate ventral ganglionic mass in the annelid. We propose that Kolmer-Agduhr cell-like mechanosensory neurons formed part of the mucociliary sole in protostome-deuterostome ancestors and diversified independently into several neuron types in annelid and vertebrate descendants.
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43
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Helm C, Karl A, Beckers P, Kaul-Strehlow S, Ulbricht E, Kourtesis I, Kuhrt H, Hausen H, Bartolomaeus T, Reichenbach A, Bleidorn C. Early evolution of radial glial cells in Bilateria. Proc Biol Sci 2018; 284:rspb.2017.0743. [PMID: 28724733 PMCID: PMC5543218 DOI: 10.1098/rspb.2017.0743] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2017] [Accepted: 06/13/2017] [Indexed: 12/13/2022] Open
Abstract
Bilaterians usually possess a central nervous system, composed of neurons and supportive cells called glial cells. Whereas neuronal cells are highly comparable in all these animals, glial cells apparently differ, and in deuterostomes, radial glial cells are found. These particular secretory glial cells may represent the archetype of all (macro) glial cells and have not been reported from protostomes so far. This has caused controversial discussions of whether glial cells represent a homologous bilaterian characteristic or whether they (and thus, centralized nervous systems) evolved convergently in the two main clades of bilaterians. By using histology, transmission electron microscopy, immunolabelling and whole-mount in situ hybridization, we show here that protostomes also possess radial glia-like cells, which are very likely to be homologous to those of deuterostomes. Moreover, our antibody staining indicates that the secretory character of radial glial cells is maintained throughout their various evolutionary adaptations. This implies an early evolution of radial glial cells in the last common ancestor of Protostomia and Deuterostomia. Furthermore, it suggests that an intraepidermal nervous system—composed of sensory cells, neurons and radial glial cells—was probably the plesiomorphic condition in the bilaterian ancestor.
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Affiliation(s)
- Conrad Helm
- Sars International Center for Marine Molecular Biology, University of Bergen, 5008 Bergen, Norway
| | - Anett Karl
- Paul-Flechsig-Institute for Brain Research, University of Leipzig, 04103 Leipzig, Germany.,Translational Center for Regenerative Medicine, University of Leipzig, 04103 Leipzig, Germany.,Carl-Ludwig-Institute for Physiology, University of Leipzig, 04103 Leipzig, Germany
| | - Patrick Beckers
- Institute of Evolutionary Biology and Ecology, University of Bonn, 53121 Bonn, Germany
| | | | - Elke Ulbricht
- Biotechnology Center, Technische Universität Dresden, 01307 Dresden, Germany
| | - Ioannis Kourtesis
- Sars International Center for Marine Molecular Biology, University of Bergen, 5008 Bergen, Norway
| | - Heidrun Kuhrt
- Paul-Flechsig-Institute for Brain Research, University of Leipzig, 04103 Leipzig, Germany
| | - Harald Hausen
- Sars International Center for Marine Molecular Biology, University of Bergen, 5008 Bergen, Norway
| | - Thomas Bartolomaeus
- Institute of Evolutionary Biology and Ecology, University of Bonn, 53121 Bonn, Germany
| | - Andreas Reichenbach
- Paul-Flechsig-Institute for Brain Research, University of Leipzig, 04103 Leipzig, Germany
| | - Christoph Bleidorn
- Museo Nacional de Ciencias Naturales, Spanish National Research Council (CSIC), 28006 Madrid, Spain
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44
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Misra M, Audoly B, Shvartsman SY. Complex structures from patterned cell sheets. Philos Trans R Soc Lond B Biol Sci 2017; 372:rstb.2015.0515. [PMID: 28348251 DOI: 10.1098/rstb.2015.0515] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/26/2016] [Indexed: 12/30/2022] Open
Abstract
The formation of three-dimensional structures from patterned epithelial sheets plays a key role in tissue morphogenesis. An important class of morphogenetic mechanisms relies on the spatio-temporal control of apical cell contractility, which can result in the localized bending of cell sheets and in-plane cell rearrangements. We have recently proposed a modified vertex model that can be used to systematically explore the connection between the two-dimensional patterns of cell properties and the emerging three-dimensional structures. Here we review the proposed modelling framework and illustrate it through the computational analysis of the vertex model that captures the salient features of the formation of the dorsal appendages during Drosophila oogenesis.This article is part of the themed issue 'Systems morphodynamics: understanding the development of tissue hardware'.
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Affiliation(s)
- M Misra
- Department of Chemical and Biological Engineering, Princeton University, Princeton, NJ 08544, USA.,Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ 08544, USA
| | - B Audoly
- LMS, École Polytechnique, CNRS, Université Paris-Saclay, 91128 Palaiseau, France
| | - S Y Shvartsman
- Department of Chemical and Biological Engineering, Princeton University, Princeton, NJ 08544, USA .,Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ 08544, USA
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45
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The Role of the Gustatory System in the Coordination of Feeding. eNeuro 2017; 4:eN-REV-0324-17. [PMID: 29159281 PMCID: PMC5694965 DOI: 10.1523/eneuro.0324-17.2017] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2017] [Revised: 10/19/2017] [Accepted: 10/25/2017] [Indexed: 11/21/2022] Open
Abstract
To survive, all animals must find, inspect, and ingest food. Behavioral coordination and control of feeding is therefore a challenge that animals must face. Here, we focus on how the gustatory system guides the precise execution of behavioral sequences that promote ingestion and suppresses competing behaviors. We summarize principles learnt from Drosophila, where underlying sensory neuronal mechanisms are illustrated in great detail. Moreover, we compare these principles with findings in other animals, where such coordination plays prominent roles. These examples suggest that the use of gustatory information for feeding coordination has an ancient origin and is prevalent throughout the animal kingdom.
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46
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Brunet T, King N. The Origin of Animal Multicellularity and Cell Differentiation. Dev Cell 2017; 43:124-140. [PMID: 29065305 PMCID: PMC6089241 DOI: 10.1016/j.devcel.2017.09.016] [Citation(s) in RCA: 234] [Impact Index Per Article: 33.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2017] [Revised: 08/31/2017] [Accepted: 09/19/2017] [Indexed: 12/14/2022]
Abstract
Over 600 million years ago, animals evolved from a unicellular or colonial organism whose cell(s) captured bacteria with a collar complex, a flagellum surrounded by a microvillar collar. Using principles from evolutionary cell biology, we reason that the transition to multicellularity required modification of pre-existing mechanisms for extracellular matrix synthesis and cytokinesis. We discuss two hypotheses for the origin of animal cell types: division of labor from ancient plurifunctional cells and conversion of temporally alternating phenotypes into spatially juxtaposed cell types. Mechanistic studies in diverse animals and their relatives promise to deepen our understanding of animal origins and cell biology.
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Affiliation(s)
- Thibaut Brunet
- Howard Hughes Medical Institute and the Department of Molecular and Cell Biology, University of California, Berkeley, CA, USA
| | - Nicole King
- Howard Hughes Medical Institute and the Department of Molecular and Cell Biology, University of California, Berkeley, CA, USA.
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47
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Abstract
Bilaterality – the possession of two orthogonal body axes – is the name-giving trait of all bilaterian animals. These body axes are established during early embryogenesis and serve as a three-dimensional coordinate system that provides crucial spatial cues for developing cells, tissues, organs and appendages. The emergence of bilaterality was a major evolutionary transition, as it allowed animals to evolve more complex body plans. Therefore, how bilaterality evolved and whether it evolved once or several times independently is a fundamental issue in evolutionary developmental biology. Recent findings from non-bilaterian animals, in particular from Cnidaria, the sister group to Bilateria, have shed new light into the evolutionary origin of bilaterality. Here, we compare the molecular control of body axes in radially and bilaterally symmetric cnidarians and bilaterians, identify the minimal set of traits common for Bilateria, and evaluate whether bilaterality arose once or more than once during evolution.
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Affiliation(s)
- Grigory Genikhovich
- Department for Molecular Evolution and Development, Centre of Organismal Systems Biology, University of Vienna, Althanstraße 14, A-1090 Vienna, Austria
| | - Ulrich Technau
- Department for Molecular Evolution and Development, Centre of Organismal Systems Biology, University of Vienna, Althanstraße 14, A-1090 Vienna, Austria
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48
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Abstract
The evolution of a nervous system as a control system of the body's functions is a key innovation of animals. Its fundamental units are neurons, highly specialized cells dedicated to fast cell-cell communication. Neurons pass signals to other neurons, muscle cells, or gland cells at specialized junctions, the synapses, where transmitters are released from vesicles in a Ca2+-dependent fashion to activate receptors in the membrane of the target cell. Reconstructing the origins of neuronal communication out of a more simple process remains a central challenge in biology. Recent genomic comparisons have revealed that all animals, including the nerveless poriferans and placozoans, share a basic set of genes for neuronal communication. This suggests that the first animal, the Urmetazoan, was already endowed with neurosecretory cells that probably started to connect into neuronal networks soon afterward. Here, we discuss scenarios for this pivotal transition in animal evolution.
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Affiliation(s)
- Frederique Varoqueaux
- Département des Neurosciences Fondamentales, Université de Lausanne, Lausanne, CH-1005 Switzerland; ,
| | - Dirk Fasshauer
- Département des Neurosciences Fondamentales, Université de Lausanne, Lausanne, CH-1005 Switzerland; ,
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49
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Senatore A, Reese TS, Smith CL. Neuropeptidergic integration of behavior in Trichoplax adhaerens, an animal without synapses. J Exp Biol 2017; 220:3381-3390. [PMID: 28931721 PMCID: PMC5612019 DOI: 10.1242/jeb.162396] [Citation(s) in RCA: 79] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2017] [Accepted: 07/04/2017] [Indexed: 12/17/2022]
Abstract
Trichoplax adhaerens is a flat, millimeter-sized marine animal that adheres to surfaces and grazes on algae. Trichoplax displays a repertoire of different feeding behaviors despite the apparent absence of a true nervous system with electrical or chemical synapses. It glides along surfaces to find food, propelled by beating cilia on cells at its ventral surface, and pauses during feeding by arresting ciliary beating. We found that when endomorphin-like peptides are applied to an animal, ciliary beating is arrested, mimicking natural feeding pauses. Antibodies against these neuropeptides label cells that express the neurosecretory proteins and voltage-gated calcium channels implicated in regulated secretion. These cells are embedded in the ventral epithelium, where they comprise only 4% of the total, and are concentrated around the edge of the animal. Each bears a cilium likely to be chemosensory and used to detect algae. Trichoplax pausing during feeding or spontaneously in the absence of food often induce their neighbors to pause as well, even neighbors not in direct contact. Pausing behavior propagates from animal to animal across distances much greater than the signal that diffuses from just one animal, so we presume that the peptides secreted from one animal elicit secretion from nearby animals. Signal amplification by peptide-induced peptide secretion explains how a small number of sensory secretory cells lacking processes and synapses can evoke a wave of peptide secretion across the entire animal to globally arrest ciliary beating and allow pausing during feeding.
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Affiliation(s)
- Adriano Senatore
- University of Toronto Mississauga, Mississauga, ON, Canada L5L 1C6
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50
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van Duijn M. Phylogenetic origins of biological cognition: convergent patterns in the early evolution of learning. Interface Focus 2017; 7:20160158. [PMID: 28479986 PMCID: PMC5413897 DOI: 10.1098/rsfs.2016.0158] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Various forms of elementary learning have recently been discovered in organisms lacking a nervous system, such as protists, fungi and plants. This finding has fundamental implications for how we view the role of convergent evolution in biological cognition. In this article, I first review the evidence for basic forms of learning in aneural organisms, focusing particularly on habituation and classical conditioning and considering the plausibility for convergent evolution of these capacities. Next, I examine the possible role of convergent evolution regarding these basic learning abilities during the early evolution of nervous systems. The evolution of nervous systems set the stage for at least two major events relevant to convergent evolution that are central to biological cognition: (i) nervous systems evolved, perhaps more than once, because of strong selection pressures for sustaining sensorimotor strategies in increasingly larger multicellular organisms and (ii) associative learning was a subsequent adaptation that evolved multiple times within the neuralia. Although convergent evolution of basic forms of learning among distantly related organisms such as protists, plants and neuralia is highly plausible, more research is needed to verify whether these forms of learning within the neuralia arose through convergent or parallel evolution.
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Affiliation(s)
- Marc van Duijn
- Faculty of Arts, Culture and Cognition, Rijksuniversiteit Groningen, Oude Boteringestraat 34, Groningen, The Netherlands
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