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Hird C, Jékely G, Williams EA. Microalgal biofilm induces larval settlement in the model marine worm Platynereis dumerilii. ROYAL SOCIETY OPEN SCIENCE 2024; 11:240274. [PMID: 39295916 PMCID: PMC11407872 DOI: 10.1098/rsos.240274] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/16/2024] [Revised: 06/17/2024] [Accepted: 08/12/2024] [Indexed: 09/21/2024]
Abstract
A free-swimming larval stage features in many marine invertebrate life cycles. To transition to a seafloor-dwelling juvenile stage, larvae need to settle out of the plankton, guided by specific environmental cues that lead them to an ideal habitat for their future life on the seafloor. Although the marine annelid Platynereis dumerilii has been cultured in research laboratories since the 1950s and has a free-swimming larval stage, specific environmental cues that induce settlement in this nereid worm are yet to be identified. Here, we demonstrate that microalgal biofilm is a key settlement cue for P. dumerilii larvae, inducing earlier onset of settlement and enhancing subsequent juvenile growth as a primary food source. We tested the settlement response of P. dumerilii to 40 different strains of microalgae, predominantly diatom species, finding that P. dumerilii have species-specific preferences in their choice of settlement substrate. The most effective diatom species for inducing P. dumerilii larval settlement were benthic pennate species including Grammatophora marina, Achnanthes brevipes and Nitzschia ovalis. The identification of specific environmental cues for P. dumerilii settlement enables a link between its ecology and the sensory and nervous system signalling that regulates larval behaviour and development. Incorporation of diatoms into P. dumerilii culture practices will improve the husbandry of this marine invertebrate model.
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Affiliation(s)
- Cameron Hird
- Scymaris Ltd, Brixham Laboratory, Freshwater Quarry, Brixham, Devon TQ5 8BA, UK
- University of Exeter, Biosciences, Faculty of Health and Life Sciences, Streatham Campus, Exeter EX4 4QD, UK
| | - Gáspár Jékely
- University of Heidelberg, Centre for Organismal Studies, Im Neuenheimer Feld 230, Heidelberg 69120, Germany
- University of Exeter Living Systems Institute, Streatham Campus, Exeter EX4 4QD, UK
| | - Elizabeth A Williams
- University of Exeter, Biosciences, Faculty of Health and Life Sciences, Streatham Campus, Exeter EX4 4QD, UK
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2
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Ertürk A. Deep 3D histology powered by tissue clearing, omics and AI. Nat Methods 2024; 21:1153-1165. [PMID: 38997593 DOI: 10.1038/s41592-024-02327-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2022] [Accepted: 05/28/2024] [Indexed: 07/14/2024]
Abstract
To comprehensively understand tissue and organism physiology and pathophysiology, it is essential to create complete three-dimensional (3D) cellular maps. These maps require structural data, such as the 3D configuration and positioning of tissues and cells, and molecular data on the constitution of each cell, spanning from the DNA sequence to protein expression. While single-cell transcriptomics is illuminating the cellular and molecular diversity across species and tissues, the 3D spatial context of these molecular data is often overlooked. Here, I discuss emerging 3D tissue histology techniques that add the missing third spatial dimension to biomedical research. Through innovations in tissue-clearing chemistry, labeling and volumetric imaging that enhance 3D reconstructions and their synergy with molecular techniques, these technologies will provide detailed blueprints of entire organs or organisms at the cellular level. Machine learning, especially deep learning, will be essential for extracting meaningful insights from the vast data. Further development of integrated structural, molecular and computational methods will unlock the full potential of next-generation 3D histology.
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Affiliation(s)
- Ali Ertürk
- Institute for Tissue Engineering and Regenerative Medicine, Helmholtz Zentrum München, Neuherberg, Germany.
- Institute for Stroke and Dementia Research, Klinikum der Universität München, Ludwig-Maximilians University, Munich, Germany.
- School of Medicine, Koç University, İstanbul, Turkey.
- Deep Piction GmbH, Munich, Germany.
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3
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Ramirez MD, Bui TN, Katz PS. Cellular-resolution gene expression mapping reveals organization in the head ganglia of the gastropod, Berghia stephanieae. J Comp Neurol 2024; 532:e25628. [PMID: 38852042 PMCID: PMC11198006 DOI: 10.1002/cne.25628] [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: 12/23/2023] [Revised: 04/25/2024] [Accepted: 05/09/2024] [Indexed: 06/10/2024]
Abstract
Gastropod molluscs such as Aplysia, Lymnaea, and Tritonia have been important for determining fundamental rules of motor control, learning, and memory because of their large, individually identifiable neurons. Yet only a small number of gastropod neurons have known molecular markers, limiting the ability to establish brain-wide structure-function relations. Here we combine high-throughput, single-cell RNA sequencing with in situ hybridization chain reaction in the nudibranch Berghia stephanieae to identify and visualize the expression of markers for cell types. Broad neuronal classes were characterized by genes associated with neurotransmitters, like acetylcholine, glutamate, serotonin, and GABA, as well as neuropeptides. These classes were subdivided by other genes including transcriptional regulators and unannotated genes. Marker genes expressed by neurons and glia formed discrete, previously unrecognized regions within and between ganglia. This study provides the foundation for understanding the fundamental cellular organization of gastropod nervous systems.
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Affiliation(s)
| | - Thi N. Bui
- Department of Biology, University of Massachusetts Amherst
| | - Paul S. Katz
- Department of Biology, University of Massachusetts Amherst
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4
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Ordoñez JF, Wollesen T. Unfolding the ventral nerve center of chaetognaths. Neural Dev 2024; 19:5. [PMID: 38720353 PMCID: PMC11078758 DOI: 10.1186/s13064-024-00182-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2023] [Accepted: 04/17/2024] [Indexed: 05/12/2024] Open
Abstract
BACKGROUND Chaetognaths are a clade of marine worm-like invertebrates with a heavily debated phylogenetic position. Their nervous system superficially resembles the protostome type, however, knowledge regarding the molecular processes involved in neurogenesis is lacking. To better understand these processes, we examined the expression profiles of marker genes involved in bilaterian neurogenesis during post-embryonic stages of Spadella cephaloptera. We also investigated whether the transcription factor encoding genes involved in neural patterning are regionally expressed in a staggered fashion along the mediolateral axis of the nerve cord as it has been previously demonstrated in selected vertebrate, insect, and annelid models. METHODS The expression patterns of genes involved in neural differentiation (elav), neural patterning (foxA, nkx2.2, pax6, pax3/7, and msx), and neuronal function (ChAT and VAChT) were examined in S. cephaloptera hatchlings and early juveniles using whole-mount fluorescent in situ hybridization and confocal microscopy. RESULTS The Sce-elav + profile of S. cephaloptera hatchlings reveals that, within 24 h of post-embryonic development, the developing neural territories are not limited to the regions previously ascribed to the cerebral ganglion, the ventral nerve center (VNC), and the sensory organs, but also extend to previously unreported CNS domains that likely contribute to the ventral cephalic ganglia. In general, the neural patterning genes are expressed in distinct neural subpopulations of the cerebral ganglion and the VNC in hatchlings, eventually becoming broadly expressed with reduced intensity throughout the CNS in early juveniles. Neural patterning gene expression domains are also present outside the CNS, including the digestive tract and sensory organs. ChAT and VAChT domains within the CNS are predominantly observed in specific subpopulations of the VNC territory adjacent to the ventral longitudinal muscles in hatchlings. CONCLUSIONS The observed spatial expression domains of bilaterian neural marker gene homologs in S. cephaloptera suggest evolutionarily conserved roles in neurogenesis for these genes among bilaterians. Patterning genes expressed in distinct regions of the VNC do not show a staggered medial-to-lateral expression profile directly superimposable to other bilaterian models. Only when the VNC is conceptually laterally unfolded from the longitudinal muscle into a flat structure, an expression pattern bearing resemblance to the proposed conserved bilaterian mediolateral regionalization becomes noticeable. This finding supports the idea of an ancestral mediolateral patterning of the trunk nervous system in bilaterians.
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Affiliation(s)
- June F Ordoñez
- Unit for Integrative Zoology, Department of Evolutionary Biology, University of Vienna, 1030, Vienna, Austria
| | - Tim Wollesen
- Unit for Integrative Zoology, Department of Evolutionary Biology, University of Vienna, 1030, Vienna, Austria.
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5
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Dai L, Zhou S, Yang C, Li J, Wang Y, Qin M, Pan L, Zhang D, Qian Z, Wu H. A bioorthogonal cell sorting strategy for isolation of desired cell phenotypes. Chem Commun (Camb) 2024; 60:1916-1919. [PMID: 38259188 DOI: 10.1039/d3cc05604j] [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: 01/24/2024]
Abstract
Here we describe a cost-effective and simplified cell sorting method using tetrazine bioorthogonal chemistry. We successfully isolated SKOV3 cells from complex mixtures, demonstrating efficacy in separating mouse lymphocytes expressing interferon and HeLa cells expressing virally transduced green fluorescent protein post-infection.
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Affiliation(s)
- Liqun Dai
- Laboratory of Drug-Targeting and Drug Delivery System of the Education Ministry and Sichuan Province, Sichuan Engineering Laboratory for Plant-Sourced Drug and Sichuan Research Center for Drug Precision Industrial Technology, West China School of Pharmacy, Sichuan University, Chengdu 610041, China.
- Department of Biotherapy, Cancer Center and State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu 610041, China.
| | - Siming Zhou
- Laboratory of Drug-Targeting and Drug Delivery System of the Education Ministry and Sichuan Province, Sichuan Engineering Laboratory for Plant-Sourced Drug and Sichuan Research Center for Drug Precision Industrial Technology, West China School of Pharmacy, Sichuan University, Chengdu 610041, China.
| | - Cheng Yang
- Laboratory of Drug-Targeting and Drug Delivery System of the Education Ministry and Sichuan Province, Sichuan Engineering Laboratory for Plant-Sourced Drug and Sichuan Research Center for Drug Precision Industrial Technology, West China School of Pharmacy, Sichuan University, Chengdu 610041, China.
| | - Jie Li
- Department of Radiology and Huaxi MR Research Center (HMRRC), Functional and Molecular Imaging Key Laboratory of Sichuan Province and Frontiers Science Center for Disease Related Molecular Network West China Hospital, Sichuan University, Chengdu 610041, China
| | - Yayue Wang
- Department of Radiology and Huaxi MR Research Center (HMRRC), Functional and Molecular Imaging Key Laboratory of Sichuan Province and Frontiers Science Center for Disease Related Molecular Network West China Hospital, Sichuan University, Chengdu 610041, China
| | - Meng Qin
- National Chengdu Center for Safety Evaluation of Drugs, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu 610041, China
| | - Lili Pan
- Department of Nuclear Medicine, Laboratory of Clinical Nuclear Medicine, West China Hospital, Sichuan University, Chengdu 610041, Sichuan, China
| | - Dan Zhang
- Laboratory of Drug-Targeting and Drug Delivery System of the Education Ministry and Sichuan Province, Sichuan Engineering Laboratory for Plant-Sourced Drug and Sichuan Research Center for Drug Precision Industrial Technology, West China School of Pharmacy, Sichuan University, Chengdu 610041, China.
| | - Zhiyong Qian
- Department of Biotherapy, Cancer Center and State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu 610041, China.
| | - Haoxing Wu
- Laboratory of Drug-Targeting and Drug Delivery System of the Education Ministry and Sichuan Province, Sichuan Engineering Laboratory for Plant-Sourced Drug and Sichuan Research Center for Drug Precision Industrial Technology, West China School of Pharmacy, Sichuan University, Chengdu 610041, China.
- Department of Radiology and Huaxi MR Research Center (HMRRC), Functional and Molecular Imaging Key Laboratory of Sichuan Province and Frontiers Science Center for Disease Related Molecular Network West China Hospital, Sichuan University, Chengdu 610041, China
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Gribkova ED, Lee CA, Brown JW, Cui J, Liu Y, Norekian T, Gillette R. A common modular design of nervous systems originating in soft-bodied invertebrates. Front Physiol 2023; 14:1263453. [PMID: 37854468 PMCID: PMC10579582 DOI: 10.3389/fphys.2023.1263453] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2023] [Accepted: 09/12/2023] [Indexed: 10/20/2023] Open
Abstract
Nervous systems of vertebrates and invertebrates show a common modular theme in the flow of information for cost-benefit decisions. Sensory inputs are incentivized by integrating stimulus qualities with motivation and memory to affect appetitive state, a system of homeostatic drives, and labelled for directionality. Appetitive state determines action responses from a repertory of possibles and transmits the decision to a premotor system that frames the selected action in motor arousal and appropriate postural and locomotion commands. These commands are then sent to the primary motor pattern generators controlling the motorneurons, with feedback at each stage. In the vertebrates, these stages are mediated by forebrain pallial derivatives for incentive and directionality (olfactory bulb, cerebral cortex, pallial amygdala, etc.) interacting with hypothalamus (homeostasis, motivation, and reward) for action selection in the forebrain basal ganglia, the mid/hindbrain reticular formation as a premotor translator for posture, locomotion, and arousal state, and the spinal cord and cranial nuclei as primary motor pattern generators. Gastropods, like the predatory sea slug Pleurobranchaea californica, show a similar organization but with differences that suggest how complex brains evolved from an ancestral soft-bodied bilaterian along with segmentation, jointed skeletons, and complex exteroceptors. Their premotor feeding network combines functions of hypothalamus and basal ganglia for homeostasis, motivation, presumed reward, and action selection for stimulus approach or avoidance. In Pleurobranchaea, the premotor analogy to the vertebrate reticular formation is the bilateral "A-cluster" of cerebral ganglion neurons that controls posture, locomotion, and serotonergic motor arousal. The A-cluster transmits motor commands to the pedal ganglia analogs of the spinal cord, for primary patterned motor output. Apparent pallial precursors are not immediately evident in Pleurobranchaea's central nervous system, but a notable candidate is a subepithelial nerve net in the peripheral head region that integrates chemotactile stimuli for incentive and directionality. Evolutionary centralization of its computational functions may have led to the olfaction-derived pallial forebrain in the ancestor's vertebrate descendants and their analogs in arthropods and annelids.
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Affiliation(s)
- Ekaterina D. Gribkova
- Coordinated Science Laboratory, University of Illinois at Urbana-Champaign, Urbana, IL, United States
| | - Colin A. Lee
- Neuroscience Program, University of Illinois at Urbana-Champaign, Urbana, IL, United States
| | - Jeffrey W. Brown
- Stanson Toshok Center for Brain Function and Repair, Rosalind Franklin University of Medicine and Science, North Chicago, IL, United States
| | - Jilai Cui
- Neuroscience Program, University of Illinois at Urbana-Champaign, Urbana, IL, United States
| | - Yichen Liu
- Department of Molecular & Integrative Physiology, University of Illinois at Urbana-Champaign, Urbana, IL, United States
| | - Tigran Norekian
- Whitney Laboratory for Marine Biosciences, University of Florida, St. Augustine, FL, United States
| | - Rhanor Gillette
- Neuroscience Program, University of Illinois at Urbana-Champaign, Urbana, IL, United States
- Department of Molecular & Integrative Physiology, University of Illinois at Urbana-Champaign, Urbana, IL, United States
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7
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Wyart C, Carbo-Tano M, Cantaut-Belarif Y, Orts-Del'Immagine A, Böhm UL. Cerebrospinal fluid-contacting neurons: multimodal cells with diverse roles in the CNS. Nat Rev Neurosci 2023; 24:540-556. [PMID: 37558908 DOI: 10.1038/s41583-023-00723-8] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/26/2023] [Indexed: 08/11/2023]
Abstract
The cerebrospinal fluid (CSF) is a complex solution that circulates around the CNS, and whose composition changes as a function of an animal's physiological state. Ciliated neurons that are bathed in the CSF - and thus referred to as CSF-contacting neurons (CSF-cNs) - are unusual polymodal interoceptive neurons. As chemoreceptors, CSF-cNs respond to variations in pH and osmolarity and to bacterial metabolites in the CSF. Their activation during infections of the CNS results in secretion of compounds to enhance host survival. As mechanosensory neurons, CSF-cNs operate together with an extracellular proteinaceous polymer known as the Reissner fibre to detect compression during spinal curvature. Once activated, CSF-cNs inhibit motor neurons, premotor excitatory neurons and command neurons to enhance movement speed and stabilize posture. At longer timescales, CSF-cNs instruct morphogenesis throughout life via the release of neuropeptides that act over long distances on skeletal muscle. Finally, recent evidence suggests that mouse CSF-cNs may act as neural stem cells in the spinal cord, inspiring new paths of investigation for repair after injury.
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Affiliation(s)
- Claire Wyart
- Institut du Cerveau (ICM), INSERM U1127, UMR CNRS 7225 Paris, Sorbonne Université, Paris, France.
| | - Martin Carbo-Tano
- Institut du Cerveau (ICM), INSERM U1127, UMR CNRS 7225 Paris, Sorbonne Université, Paris, France
| | - Yasmine Cantaut-Belarif
- Institut du Cerveau (ICM), INSERM U1127, UMR CNRS 7225 Paris, Sorbonne Université, Paris, France
| | | | - Urs L Böhm
- NeuroCure Cluster of Excellence, Charité Universitätsmedizin Berlin, Berlin, Germany
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8
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Wilson AC, Sweeney LB. Spinal cords: Symphonies of interneurons across species. Front Neural Circuits 2023; 17:1146449. [PMID: 37180760 PMCID: PMC10169611 DOI: 10.3389/fncir.2023.1146449] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2023] [Accepted: 03/23/2023] [Indexed: 05/16/2023] Open
Abstract
Vertebrate movement is orchestrated by spinal inter- and motor neurons that, together with sensory and cognitive input, produce dynamic motor behaviors. These behaviors vary from the simple undulatory swimming of fish and larval aquatic species to the highly coordinated running, reaching and grasping of mice, humans and other mammals. This variation raises the fundamental question of how spinal circuits have changed in register with motor behavior. In simple, undulatory fish, exemplified by the lamprey, two broad classes of interneurons shape motor neuron output: ipsilateral-projecting excitatory neurons, and commissural-projecting inhibitory neurons. An additional class of ipsilateral inhibitory neurons is required to generate escape swim behavior in larval zebrafish and tadpoles. In limbed vertebrates, a more complex spinal neuron composition is observed. In this review, we provide evidence that movement elaboration correlates with an increase and specialization of these three basic interneuron types into molecularly, anatomically, and functionally distinct subpopulations. We summarize recent work linking neuron types to movement-pattern generation across fish, amphibians, reptiles, birds and mammals.
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Affiliation(s)
| | - Lora B. Sweeney
- Institute of Science and Technology Austria (IST Austria), Klosterneuburg, Lower Austria, Austria
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9
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Tissue dissociation for single-cell and single-nuclei RNA sequencing for low amounts of input material. Front Zool 2022; 19:27. [DOI: 10.1186/s12983-022-00472-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2022] [Accepted: 10/27/2022] [Indexed: 11/15/2022] Open
Abstract
Abstract
Background
Recent technological advances opened the opportunity to simultaneously study gene expression for thousands of individual cells on a genome-wide scale. The experimental accessibility of such single-cell RNA sequencing (scRNAseq) approaches allowed gaining insights into the cell type composition of heterogeneous tissue samples of animal model systems and emerging models alike. A major prerequisite for a successful application of the method is the dissociation of complex tissues into individual cells, which often requires large amounts of input material and harsh mechanical, chemical and temperature conditions. However, the availability of tissue material may be limited for small animals, specific organs, certain developmental stages or if samples need to be acquired from collected specimens. Therefore, we evaluated different dissociation protocols to obtain single cells from small tissue samples of Drosophila melanogaster eye-antennal imaginal discs.
Results
We show that a combination of mechanical and chemical dissociation resulted in sufficient high-quality cells. As an alternative, we tested protocols for the isolation of single nuclei, which turned out to be highly efficient for fresh and frozen tissue samples. Eventually, we performed scRNAseq and single-nuclei RNA sequencing (snRNAseq) to show that the best protocols for both methods successfully identified relevant cell types. At the same time, snRNAseq resulted in less artificial gene expression that is caused by rather harsh dissociation conditions needed to obtain single cells for scRNAseq. A direct comparison of scRNAseq and snRNAseq data revealed that both datasets share biologically relevant genes among the most variable genes, and we showed differences in the relative contribution of the two approaches to identified cell types.
Conclusion
We present two dissociation protocols that allow isolating single cells and single nuclei, respectively, from low input material. Both protocols resulted in extraction of high-quality RNA for subsequent scRNAseq or snRNAseq applications. If tissue availability is limited, we recommend the snRNAseq procedure of fresh or frozen tissue samples as it is perfectly suited to obtain thorough insights into cellular diversity of complex tissue.
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10
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Niu B, Nguyen Bach T, Chen X, Raghunath Chandratre K, Isaac Murray J, Zhao Z, Zhang M. Computational modeling and analysis of the morphogenetic domain signaling networks regulating C. elegans embryogenesis. Comput Struct Biotechnol J 2022; 20:3653-3666. [PMID: 35891777 PMCID: PMC9289785 DOI: 10.1016/j.csbj.2022.05.058] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2021] [Revised: 05/29/2022] [Accepted: 05/30/2022] [Indexed: 11/03/2022] Open
Abstract
Caenorhabditis elegans, often referred to as the ‘roundworm’, provides a powerful model for studying cell autonomous and cell–cell interactions through the direct observation of embryonic development in vivo. By leveraging the precisely mapped cell lineage at single cell resolution, we are able to study at a systems level how early embryonic cells communicate across morphogenetic domains for the coordinated processes of gene expressions and collective cellular behaviors that regulate tissue morphogenesis. In this study, we developed a computational framework for the exploration of the morphogenetic domain cell signaling networks that may regulate C. elegans gastrulation and embryonic organogenesis. We demonstrated its utility by producing the following results, i) established a virtual reference model of developing C. elegans embryos through the spatiotemporal alignment of individual embryo cell nuclear imaging samples; ii) integrated the single cell spatiotemporal gene expression profile with the established virtual embryo model by data pooling; iii) trained a Machine Learning model (Random Forest Regression), which predicts accurately the spatial positions of the cells given their gene expression profiles for a given developmental time (e.g. total cell number of the embryo); iv) enabled virtual 4-dimensional tomographic graphical modeling of single cell data; v) inferred the biology signaling pathways that act in each of morphogenetic domains by meta-data analysis. It is intriguing that the morphogenetic domain cell signaling network seems to involve some crosstalk of multiple biology signaling pathways during the formation of tissue boundary pattern. Lastly, we developed the Software tool ‘Embryo aligner version 1.0’ and provided it as an Open Source program to the research community for virtual embryo modeling, and phenotype perturbation analyses (https://github.com/csniuben/embryo_aligner/wiki and https://bioinfo89.github.io/C.elegansEmbryonicOrganogenesisweb/).
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11
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Keenan SE, Avdeeva M, Yang L, Alber DS, Wieschaus EF, Shvartsman SY. Dynamics of Drosophila endoderm specification. Proc Natl Acad Sci U S A 2022; 119:e2112892119. [PMID: 35412853 PMCID: PMC9169638 DOI: 10.1073/pnas.2112892119] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2021] [Accepted: 02/06/2022] [Indexed: 11/18/2022] Open
Abstract
During early Drosophila embryogenesis, a network of gene regulatory interactions orchestrates terminal patterning, playing a critical role in the subsequent formation of the gut. We utilized CRISPR gene editing at endogenous loci to create live reporters of transcription and light-sheet microscopy to monitor the individual components of the posterior gut patterning network across 90 min prior to gastrulation. We developed a computational approach for fusing imaging datasets of the individual components into a common multivariable trajectory. Data fusion revealed low intrinsic dimensionality of posterior patterning and cell fate specification in wild-type embryos. The simple structure that we uncovered allowed us to construct a model of interactions within the posterior patterning regulatory network and make testable predictions about its dynamics at the protein level. The presented data fusion strategy is a step toward establishing a unified framework that would explore how stochastic spatiotemporal signals give rise to highly reproducible morphogenetic outcomes.
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Affiliation(s)
- Shannon E. Keenan
- Department of Chemical and Biological Engineering, Princeton University, Princeton, NJ 08540
- The Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ 08540
| | - Maria Avdeeva
- Center for Computational Biology, Flatiron Institute, Simons Foundation, New York, NY 10010
| | - Liu Yang
- The Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ 08540
| | - Daniel S. Alber
- Department of Chemical and Biological Engineering, Princeton University, Princeton, NJ 08540
- The Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ 08540
| | - Eric F. Wieschaus
- The Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ 08540
- Department of Molecular Biology, Princeton University, Princeton, NJ 08540
| | - Stanislav Y. Shvartsman
- The Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ 08540
- Center for Computational Biology, Flatiron Institute, Simons Foundation, New York, NY 10010
- Department of Molecular Biology, Princeton University, Princeton, NJ 08540
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12
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Salamanca-Díaz DA, Schulreich SM, Cole AG, Wanninger A. Single-Cell RNA Sequencing Atlas From a Bivalve Larva Enhances Classical Cell Lineage Studies. Front Ecol Evol 2022. [DOI: 10.3389/fevo.2021.783984] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Ciliated trochophore-type larvae are widespread among protostome animals with spiral cleavage. The respective phyla are often united into the superclade Spiralia or Lophotrochozoa that includes, for example, mollusks, annelids, and platyhelminths. Mollusks (bivalves, gastropods, cephalopods, polyplacophorans, and their kin) in particular are known for their morphological innovations and lineage-specific plasticity of homologous characters (e.g., radula, shell, foot, neuromuscular systems), raising questions concerning the cell types and the molecular toolkit that underlie this variation. Here, we report on the gene expression profile of individual cells of the trochophore larva of the invasive freshwater bivalve Dreissena rostriformis as inferred from single cell RNA sequencing. We generated transcriptomes of 632 individual cells and identified seven transcriptionally distinct cell populations. Developmental trajectory analyses identify cell populations that, for example, share an ectodermal origin such as the nervous system, the shell field, and the prototroch. To annotate these cell populations, we examined ontology terms from the gene sets that characterize each individual cluster. These were compared to gene expression data previously reported from other lophotrochozoans. Genes expected to be specific to certain tissues, such as Hox1 (in the shell field), Caveolin (in prototrochal cells), or FoxJ (in other cillia-bearing cells) provide evidence that the recovered cell populations contribute to various distinct tissues and organs known from morphological studies. This dataset provides the first molecular atlas of gene expression underlying bivalve organogenesis and generates an important framework for future comparative studies into cell and tissue type development in Mollusca and Metazoa as a whole.
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13
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Ponz-Segrelles G, Ribeiro RP, Aguado MT. Monsters reveal patterns: bifurcated annelids and their implications for the study of development and evolution. Biol Rev Camb Philos Soc 2021; 97:896-922. [PMID: 34931440 DOI: 10.1111/brv.12826] [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: 06/24/2021] [Revised: 12/03/2021] [Accepted: 12/06/2021] [Indexed: 11/30/2022]
Abstract
During recent decades, the study of anatomical anomalies has been of great relevance for research on development and its evolution. Yet most animal groups have never been studied under this perspective. In annelids, one of the most common and remarkable anomalies is anteroposterior axis bifurcation, that is animals that have two or more heads and/or tails. Bifurcated annelids were first described in the 18th century and have been occasionally reported since then. However, these animals have rarely been considered other than curiosities, one-off anomalies, or monsters, and a condensed but comprehensive analysis of this phenomenon is lacking. Such an analysis of the existing knowledge is necessary for addressing the different patterns of annelid bifurcation, as well as to understand possible developmental mechanisms behind them and their evolution. In this review we summarize reports of annelid bifurcation published during the last 275 years and the wide variety of anatomies they present. Our survey reveals bifurcation as a widespread phenomenon found all over the annelid tree. Moreover, it also shows that bifurcations can be classified into different types according to anatomy (lateral versus dorsoventral) or developmental origin (embryonic versus postembryonic, the latter occurring in relation to regeneration, reproduction, or growth). Regarding embryos, three different types of bifurcation can be found: conjoined twins (in clitellates); Janus embryos (two posterior ends with a single head which shows duplicated structures); and duplicitas cruciata embryos (with anterior and posterior bifurcation with a 90° rotation). In adults, we show that while lateral bifurcation can result in well-integrated phenotypes, dorsoventral bifurcation cannot since it requires the discontinuity of at least some internal organs. The relevance of this distinction is highlighted in the case of the Ribbon Clade, a group of syllid annelids in which some species reproduce by collateral and successive gemmiparity (which involves dorsoventral bifurcation), while others grow by branching laterally. Although most known cases of bifurcation came from accidental findings in the wild or were unintentionally produced, experimental studies resulting in the induction of bifurcation of both embryos and adults are also reviewed. In embryos, these experimental studies show how mechanical or chemical disruption of the zygote can result in bifurcation. In adults, the ventral nervous system and the digestive tract seem to play a role in the induction of bifurcation. Based on the reviewed evidence, we argue that the long-forgotten study of annelid developmental anomalies should be incorporated into the growing field of annelid EvoDevo and examined with modern techniques and perspectives.
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Affiliation(s)
- Guillermo Ponz-Segrelles
- Departamento de Biología, Facultad de Ciencias, Universidad Autónoma de Madrid, Darwin, 2, Madrid, 28049, Spain
| | - Rannyele P Ribeiro
- Departamento de Biología, Facultad de Ciencias, Universidad Autónoma de Madrid, Darwin, 2, Madrid, 28049, Spain.,Marine Biological Laboratory, 7 MBL Street, Woods Hole, MA, 02543, U.S.A
| | - M Teresa Aguado
- Biodiversitätsmuseum, Animal Evolution & Biodiversity, Georg-August-Universität Göttingen, Untere Karspüle 2, Göttingen, 37073, Germany
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Arendt D, Urzainqui IQ, Vergara HM. The conserved core of the nereid brain: Circular CNS, apical nervous system and lhx6-arx-dlx neurons. Curr Opin Neurobiol 2021; 71:178-187. [PMID: 34861534 DOI: 10.1016/j.conb.2021.11.008] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2021] [Revised: 11/03/2021] [Accepted: 11/09/2021] [Indexed: 11/28/2022]
Abstract
When bilaterian animals first emerged, an enhanced perception of the Precambrian environment was key to their stunning success. This occurred through the acquisition of an anterior brain, as found in most extant bilaterians. What were the core circuits of the first brain, and how do they relate to today's diversity? With two landmark resources - the full connectome and a multimodal cellular atlas combining gene expression and ultrastructure - the young worm of the marine annelid Platynereis dumerilii takes center stage in comparative bilaterian neuroanatomy. The new data suggest a composite structure of the ancestral bilaterian brain, with the anterior end of a circular CNS fused to a sensory-neurosecretory apical system, and with lhx6-arx-dlx chemosensory circuits giving rise to associative centers in the descending bilaterian lineages.
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Affiliation(s)
- Detlev Arendt
- European Molecular Biology Laboratory, Developmental Biology Unit, Meyerhofstrasse 1, 69012, Heidelberg, Germany.
| | - Idoia Quintana Urzainqui
- European Molecular Biology Laboratory, Developmental Biology Unit, Meyerhofstrasse 1, 69012, Heidelberg, Germany
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15
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Chari T, Weissbourd B, Gehring J, Ferraioli A, Leclère L, Herl M, Gao F, Chevalier S, Copley RR, Houliston E, Anderson DJ, Pachter L. Whole-animal multiplexed single-cell RNA-seq reveals transcriptional shifts across Clytia medusa cell types. SCIENCE ADVANCES 2021; 7:eabh1683. [PMID: 34826233 PMCID: PMC8626072 DOI: 10.1126/sciadv.abh1683] [Citation(s) in RCA: 35] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/20/2021] [Accepted: 10/06/2021] [Indexed: 05/12/2023]
Abstract
We present an organism-wide, transcriptomic cell atlas of the hydrozoan medusa Clytia hemisphaerica and describe how its component cell types respond to perturbation. Using multiplexed single-cell RNA sequencing, in which individual animals were indexed and pooled from control and perturbation conditions into a single sequencing run, we avoid artifacts from batch effects and are able to discern shifts in cell state in response to organismal perturbations. This work serves as a foundation for future studies of development, function, and regeneration in a genetically tractable jellyfish species. Moreover, we introduce a powerful workflow for high-resolution, whole-animal, multiplexed single-cell genomics that is readily adaptable to other traditional or nontraditional model organisms.
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Affiliation(s)
- Tara Chari
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA
| | - Brandon Weissbourd
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA
- Tianqiao and Chrissy Chen Institute for Neuroscience, Pasadena, CA 91125, USA
- Howard Hughes Medical Institute, California Institute of Technology, Pasadena, CA 91125, USA
| | - Jase Gehring
- Department of Genome Sciences, University of Washington, Seattle, WA 98195, USA
| | - Anna Ferraioli
- Sorbonne Université, CNRS, Laboratoire de Biologie du Développement de Villefranche-sur-mer (LBDV), 06230, France
| | - Lucas Leclère
- Sorbonne Université, CNRS, Laboratoire de Biologie du Développement de Villefranche-sur-mer (LBDV), 06230, France
| | - Makenna Herl
- University of New Hampshire School of Law, Concord, NH 03301, USA
| | - Fan Gao
- Caltech Bioinformatics Resource Center, California Institute of Technology, Pasadena, CA 91125, USA
| | - Sandra Chevalier
- Sorbonne Université, CNRS, Laboratoire de Biologie du Développement de Villefranche-sur-mer (LBDV), 06230, France
| | - Richard R. Copley
- Sorbonne Université, CNRS, Laboratoire de Biologie du Développement de Villefranche-sur-mer (LBDV), 06230, France
| | - Evelyn Houliston
- Sorbonne Université, CNRS, Laboratoire de Biologie du Développement de Villefranche-sur-mer (LBDV), 06230, France
| | - David J. Anderson
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA
- Tianqiao and Chrissy Chen Institute for Neuroscience, Pasadena, CA 91125, USA
- Howard Hughes Medical Institute, California Institute of Technology, Pasadena, CA 91125, USA
| | - Lior Pachter
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA
- Department of Computing and Mathematical Sciences, California Institute of Technology, Pasadena, CA 91125, USA
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16
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Özpolat BD, Randel N, Williams EA, Bezares-Calderón LA, Andreatta G, Balavoine G, Bertucci PY, Ferrier DEK, Gambi MC, Gazave E, Handberg-Thorsager M, Hardege J, Hird C, Hsieh YW, Hui J, Mutemi KN, Schneider SQ, Simakov O, Vergara HM, Vervoort M, Jékely G, Tessmar-Raible K, Raible F, Arendt D. The Nereid on the rise: Platynereis as a model system. EvoDevo 2021; 12:10. [PMID: 34579780 PMCID: PMC8477482 DOI: 10.1186/s13227-021-00180-3] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2021] [Accepted: 08/20/2021] [Indexed: 01/02/2023] Open
Abstract
The Nereid Platynereis dumerilii (Audouin and Milne Edwards (Annales des Sciences Naturelles 1:195-269, 1833) is a marine annelid that belongs to the Nereididae, a family of errant polychaete worms. The Nereid shows a pelago-benthic life cycle: as a general characteristic for the superphylum of Lophotrochozoa/Spiralia, it has spirally cleaving embryos developing into swimming trochophore larvae. The larvae then metamorphose into benthic worms living in self-spun tubes on macroalgae. Platynereis is used as a model for genetics, regeneration, reproduction biology, development, evolution, chronobiology, neurobiology, ecology, ecotoxicology, and most recently also for connectomics and single-cell genomics. Research on the Nereid started with studies on eye development and spiralian embryogenesis in the nineteenth and early twentieth centuries. Transitioning into the molecular era, Platynereis research focused on posterior growth and regeneration, neuroendocrinology, circadian and lunar cycles, fertilization, and oocyte maturation. Other work covered segmentation, photoreceptors and other sensory cells, nephridia, and population dynamics. Most recently, the unique advantages of the Nereid young worm for whole-body volume electron microscopy and single-cell sequencing became apparent, enabling the tracing of all neurons in its rope-ladder-like central nervous system, and the construction of multimodal cellular atlases. Here, we provide an overview of current topics and methodologies for P. dumerilii, with the aim of stimulating further interest into our unique model and expanding the active and vibrant Platynereis community.
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Affiliation(s)
- B. Duygu Özpolat
- Eugene Bell Center for Regenerative Biology and Tissue Engineering, Marine Biological Laboratory, Woods Hole, MA 02543 USA
| | - Nadine Randel
- Department of Zoology, University of Cambridge, Downing Street, Cambridge, CB2 3EJ UK
| | - Elizabeth A. Williams
- Biosciences, College of Life and Environmental Sciences, University of Exeter, Exeter, UK
| | | | - Gabriele Andreatta
- Max Perutz Labs, University of Vienna, Dr. Bohr-Gasse 9/4, 1030 Vienna, Austria
| | - Guillaume Balavoine
- Institut Jacques Monod, University of Paris/CNRS, 15 rue Hélène Brion, 75013 Paris, France
| | - Paola Y. Bertucci
- European Molecular Biology Laboratory, Developmental Biology Unit, Meyerhofstrasse 1, 69117 Heidelberg, Germany
| | - David E. K. Ferrier
- Gatty Marine Laboratory, The Scottish Oceans Institute, University of St Andrews, East Sands, St Andrews, Fife, KY16 8LB UK
| | | | - Eve Gazave
- Institut Jacques Monod, University of Paris/CNRS, 15 rue Hélène Brion, 75013 Paris, France
| | - Mette Handberg-Thorsager
- Max Planck Institute of Molecular Cell Biology and Genetics, Pfotenhauerstraße 108, 01307 Dresden, Germany
| | - Jörg Hardege
- Department of Biological & Marine Sciences, Hull University, Cottingham Road, Hull, HU67RX UK
| | - Cameron Hird
- Living Systems Institute, University of Exeter, Stocker Road, Exeter, UK
| | - Yu-Wen Hsieh
- Max Planck Institute of Molecular Cell Biology and Genetics, Pfotenhauerstraße 108, 01307 Dresden, Germany
| | - Jerome Hui
- School of Life Sciences, Simon F.S. Li Marine Science Laboratory, State Key Laboratory of Agrobiotechnology, The Chinese University of Hong Kong, Hong Kong, China
| | - Kevin Nzumbi Mutemi
- European Molecular Biology Laboratory, Developmental Biology Unit, Meyerhofstrasse 1, 69117 Heidelberg, Germany
| | - Stephan Q. Schneider
- Institute of Cellular and Organismic Biology, Academia Sinica, No. 128, Sec. 2, Academia Road, Nankang, Taipei, 11529 Taiwan
| | - Oleg Simakov
- Department for Neurosciences and Developmental Biology, University of Vienna, Vienna, Austria
| | - Hernando M. Vergara
- Sainsbury Wellcome Centre for Neural Circuits and Behaviour, Howland Street 25, London, W1T 4JG UK
| | - Michel Vervoort
- Institut Jacques Monod, University of Paris/CNRS, 15 rue Hélène Brion, 75013 Paris, France
| | - Gáspár Jékely
- Living Systems Institute, University of Exeter, Stocker Road, Exeter, UK
| | | | - Florian Raible
- Max Perutz Labs, University of Vienna, Dr. Bohr-Gasse 9/4, 1030 Vienna, Austria
| | - Detlev Arendt
- European Molecular Biology Laboratory, Developmental Biology Unit, Meyerhofstrasse 1, 69117 Heidelberg, Germany
- Centre for Organismal Studies (COS), University of Heidelberg, 69120 Heidelberg, Germany
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17
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Whole-body integration of gene expression and single-cell morphology. Cell 2021; 184:4819-4837.e22. [PMID: 34380046 PMCID: PMC8445025 DOI: 10.1016/j.cell.2021.07.017] [Citation(s) in RCA: 37] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2020] [Revised: 05/05/2021] [Accepted: 07/14/2021] [Indexed: 01/10/2023]
Abstract
Animal bodies are composed of cell types with unique expression programs that implement their distinct locations, shapes, structures, and functions. Based on these properties, cell types assemble into specific tissues and organs. To systematically explore the link between cell-type-specific gene expression and morphology, we registered an expression atlas to a whole-body electron microscopy volume of the nereid Platynereis dumerilii. Automated segmentation of cells and nuclei identifies major cell classes and establishes a link between gene activation, chromatin topography, and nuclear size. Clustering of segmented cells according to gene expression reveals spatially coherent tissues. In the brain, genetically defined groups of neurons match ganglionic nuclei with coherent projections. Besides interneurons, we uncover sensory-neurosecretory cells in the nereid mushroom bodies, which thus qualify as sensory organs. They furthermore resemble the vertebrate telencephalon by molecular anatomy. We provide an integrated browser as a Fiji plugin for remote exploration of all available multimodal datasets. A cellular atlas integrates gene expression and ultrastructure for an entire annelid Morphometry of all segmented cells, nuclei, and chromatin categorizes cell classes Molecular anatomy and projectome of head ganglionic nuclei and mushroom bodies An open-source browser for multimodal big image data exploration and analysis
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18
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Carrillo-Baltodano AM, Seudre O, Guynes K, Martín-Durán JM. Early embryogenesis and organogenesis in the annelid Owenia fusiformis. EvoDevo 2021; 12:5. [PMID: 33971947 PMCID: PMC8111721 DOI: 10.1186/s13227-021-00176-z] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2021] [Accepted: 04/23/2021] [Indexed: 12/20/2022] Open
Abstract
BACKGROUND Annelids are a diverse group of segmented worms within Spiralia, whose embryos exhibit spiral cleavage and a variety of larval forms. While most modern embryological studies focus on species with unequal spiral cleavage nested in Pleistoannelida (Sedentaria + Errantia), a few recent studies looked into Owenia fusiformis, a member of the sister group to all remaining annelids and thus a key lineage to understand annelid and spiralian evolution and development. However, the timing of early cleavage and detailed morphogenetic events leading to the formation of the idiosyncratic mitraria larva of O. fusiformis remain largely unexplored. RESULTS Owenia fusiformis undergoes equal spiral cleavage where the first quartet of animal micromeres are slightly larger than the vegetal macromeres. Cleavage results in a coeloblastula approximately 5 h post-fertilization (hpf) at 19 °C. Gastrulation occurs via invagination and completes 4 h later, with putative mesodermal precursors and the chaetoblasts appearing 10 hpf at the dorso-posterior side. Soon after, at 11 hpf, the apical tuft emerges, followed by the first neurons (as revealed by the expression of elav1 and synaptotagmin-1) in the apical organ and the prototroch by 13 hpf. Muscles connecting the chaetal sac to various larval tissues develop around 18 hpf and by the time the mitraria is fully formed at 22 hpf, there are FMRFamide+ neurons in the apical organ and prototroch, the latter forming a prototrochal ring. As the mitraria feeds, it grows in size and the prototroch expands through active proliferation. The larva becomes competent after ~ 3 weeks post-fertilization at 15 °C, when a conspicuous juvenile rudiment has formed ventrally. CONCLUSIONS Owenia fusiformis embryogenesis is similar to that of other equal spiral cleaving annelids, supporting that equal cleavage is associated with the formation of a coeloblastula, gastrulation via invagination, and a feeding trochophore-like larva in Annelida. The nervous system of the mitraria larva forms earlier and is more elaborated than previously recognized and develops from anterior to posterior, which is likely an ancestral condition to Annelida. Altogether, our study identifies the major developmental events during O. fusiformis ontogeny, defining a conceptual framework for future investigations.
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Affiliation(s)
| | - Océane Seudre
- School of Biological and Chemical Sciences, Queen Mary University of London, London, E1 4NS, UK
| | - Kero Guynes
- School of Biological and Chemical Sciences, Queen Mary University of London, London, E1 4NS, UK
| | - José María Martín-Durán
- School of Biological and Chemical Sciences, Queen Mary University of London, London, E1 4NS, UK
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19
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Sur A, Meyer NP. Resolving Transcriptional States and Predicting Lineages in the Annelid Capitella teleta Using Single-Cell RNAseq. Front Ecol Evol 2021. [DOI: 10.3389/fevo.2020.618007] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Evolution and diversification of cell types has contributed to animal evolution. However, gene regulatory mechanisms underlying cell fate acquisition during development remains largely uncharacterized in spiralians. Here we use a whole-organism, single-cell transcriptomic approach to map larval cell types in the annelid Capitella teleta at 24- and 48-h post gastrulation (stages 4 and 5). We identified eight unique cell clusters (undifferentiated precursors, ectoderm, muscle, ciliary-band, gut, neurons, neurosecretory cells, and protonephridia), thus helping to identify uncharacterized molecular signatures such as previously unknown neurosecretory cell markers in C. teleta. Analysis of coregulatory programs in individual clusters revealed gene interactions that can be used for comparisons of cell types across taxa. We examined the neural and neurosecretory clusters more deeply and characterized a differentiation trajectory starting from dividing precursors to neurons using Monocle3 and velocyto. Pseudotime analysis along this trajectory identified temporally-distinct cell states undergoing progressive gene expression changes over time. Our data revealed two potentially distinct neural differentiation trajectories including an early trajectory for brain neurosecretory cells. This work provides a valuable resource for future functional investigations to better understanding neurogenesis and the transitions from neural precursors to neurons in an annelid.
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Abstract
Hemichordates, along with echinoderms and chordates, belong to the lineage of bilaterians called the deuterostomes. Their phylogenetic position as an outgroup to chordates provides an opportunity to investigate the evolutionary origins of the chordate body plan and reconstruct ancestral deuterostome characters. The body plans of the hemichordates and chordates are organizationally divergent making anatomical comparisons very challenging. The developmental underpinnings of animal body plans are often more conservative than the body plans they regulate, and offer a novel data set for making comparisons between morphologically divergent body architectures. Here I review the hemichordate developmental data generated over the past 20 years that further test hypotheses of proposed morphological affinities between the two taxa, but also compare the conserved anteroposterior, dorsoventral axial patterning programs and germ layer specification programs. These data provide an opportunity to determine which developmental programs are ancestral deuterostome or bilaterian innovations, and which ones occurred in stem chordates or vertebrates representing developmental novelties of the chordate body plan.
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21
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Yang L, Wang F, Strähle U. The Genetic Programs Specifying Kolmer-Agduhr Interneurons. Front Neurosci 2020; 14:577879. [PMID: 33162880 PMCID: PMC7581942 DOI: 10.3389/fnins.2020.577879] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Accepted: 09/15/2020] [Indexed: 01/21/2023] Open
Abstract
Kolmer-Agduhr (KA) cells are a subgroup of interneurons positioned adjacent to the neurocoele with cilia on the apical surface protruding into the central canal of the spinal cord. Although KA cells were identified almost a century ago, their development and functions are only beginning to be unfolded. Recent studies have revealed the characteristics of KA cells in greater detail, including their spatial distribution, the timing of their differentiation, and their specification via extrinsic signaling and a unique combination of transcription factors in zebrafish and mouse. Cell lineage-tracing experiments have demonstrated that two subsets of KA cells, named KA' and KA" cells, differentiate from motoneuronal progenitors and floor-plate precursors, respectively, in both zebrafish and mouse. Although KA' and KA" cells originate from different progenitors/precursors, they each share a common set of transcription factors. Intriguingly, the combination of transcription factors that promote the acquisition of KA' cell characteristics differs from those that promote a KA" cell identity. In addition, KA' and KA" cells exhibit separable neuronal targets and differential responses to bending of the spinal cord. In this review, we summarize what is currently known about the genetic programs defining the identities of KA' and KA" cell identities. We then discuss how these two subgroups of KA cells are genetically specified.
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Affiliation(s)
- Lixin Yang
- State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing, China.,Center for Global Health, School of Public Health, Nanjing Medical University, Nanjing, China
| | - Feifei Wang
- State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing, China
| | - Uwe Strähle
- Institute of Biological and Chemical Systems - Biological Information Processing, Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany
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22
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Kumar S, Tumu SC, Helm C, Hausen H. The development of early pioneer neurons in the annelid Malacoceros fuliginosus. BMC Evol Biol 2020; 20:117. [PMID: 32928118 PMCID: PMC7489019 DOI: 10.1186/s12862-020-01680-x] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2019] [Accepted: 08/27/2020] [Indexed: 12/13/2022] Open
Abstract
BACKGROUND Nervous system development is an interplay of many processes: the formation of individual neurons, which depends on whole-body and local patterning processes, and the coordinated growth of neurites and synapse formation. While knowledge of neural patterning in several animal groups is increasing, data on pioneer neurons that create the early axonal scaffold are scarce. Here we studied the first steps of nervous system development in the annelid Malacoceros fuliginosus. RESULTS We performed a dense expression profiling of a broad set of neural genes. We found that SoxB expression begins at 4 h postfertilization, and shortly later, the neuronal progenitors can be identified at the anterior and the posterior pole by the transient and dynamic expression of proneural genes. At 9 hpf, the first neuronal cells start differentiating, and we provide a detailed description of axonal outgrowth of the pioneer neurons that create the primary neuronal scaffold. Tracing back the clonal origin of the ventral nerve cord pioneer neuron revealed that it is a descendant of the blastomere 2d (2d221), which after 7 cleavages starts expressing Neurogenin, Acheate-Scute and NeuroD. CONCLUSIONS We propose that an anterior and posterior origin of the nervous system is ancestral in annelids. We suggest that closer examination of the first pioneer neurons will be valuable in better understanding of nervous system development in spirally cleaving animals, to determine the potential role of cell-intrinsic properties in neuronal specification and to resolve the evolution of nervous systems.
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Affiliation(s)
- Suman Kumar
- Sars International Centre for Marine Molecular Biology, University of Bergen, Bergen, Norway
| | - Sharat Chandra Tumu
- Sars International Centre for Marine Molecular Biology, University of Bergen, Bergen, Norway
| | - Conrad Helm
- Sars International Centre for Marine Molecular Biology, University of Bergen, Bergen, Norway.,Present Address: Johann-Friedrich-Blumenbach Institute for Zoology and Anthropology, Georg-August-Universität Göttingen, Göttingen, Germany
| | - Harald Hausen
- Sars International Centre for Marine Molecular Biology, University of Bergen, Bergen, Norway.
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23
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Hartmann J, Wong M, Gallo E, Gilmour D. An image-based data-driven analysis of cellular architecture in a developing tissue. eLife 2020; 9:e55913. [PMID: 32501214 PMCID: PMC7274788 DOI: 10.7554/elife.55913] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2020] [Accepted: 05/24/2020] [Indexed: 12/22/2022] Open
Abstract
Quantitative microscopy is becoming increasingly crucial in efforts to disentangle the complexity of organogenesis, yet adoption of the potent new toolbox provided by modern data science has been slow, primarily because it is often not directly applicable to developmental imaging data. We tackle this issue with a newly developed algorithm that uses point cloud-based morphometry to unpack the rich information encoded in 3D image data into a straightforward numerical representation. This enabled us to employ data science tools, including machine learning, to analyze and integrate cell morphology, intracellular organization, gene expression and annotated contextual knowledge. We apply these techniques to construct and explore a quantitative atlas of cellular architecture for the zebrafish posterior lateral line primordium, an experimentally tractable model of complex self-organized organogenesis. In doing so, we are able to retrieve both previously established and novel biologically relevant patterns, demonstrating the potential of our data-driven approach.
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Affiliation(s)
- Jonas Hartmann
- Cell Biology and Biophysics Unit, European Molecular Biology Laboratory (EMBL)HeidelbergGermany
| | - Mie Wong
- Institute of Molecular Life Sciences, University of Zurich (UZH)ZurichSwitzerland
| | - Elisa Gallo
- Cell Biology and Biophysics Unit, European Molecular Biology Laboratory (EMBL)HeidelbergGermany
- Institute of Molecular Life Sciences, University of Zurich (UZH)ZurichSwitzerland
- Collaboration for joint PhD degree between EMBL and Heidelberg University, Faculty of BiosciencesHeidelbergGermany
| | - Darren Gilmour
- Institute of Molecular Life Sciences, University of Zurich (UZH)ZurichSwitzerland
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24
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Kuehn E, Stockinger AW, Girard J, Raible F, Özpolat BD. A scalable culturing system for the marine annelid Platynereis dumerilii. PLoS One 2019; 14:e0226156. [PMID: 31805142 PMCID: PMC6894799 DOI: 10.1371/journal.pone.0226156] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2019] [Accepted: 11/20/2019] [Indexed: 12/16/2022] Open
Abstract
Platynereis dumerilii is a marine segmented worm (annelid) with externally fertilized embryos and it can be cultured for the full life cycle in the laboratory. The accessibility of embryos and larvae combined with the breadth of the established molecular and functional techniques has made P. dumerilii an attractive model for studying development, cell lineages, cell type evolution, reproduction, regeneration, the nervous system, and behavior. Traditionally, these worms have been kept in rooms dedicated for their culture. This allows for the regulation of temperature and light cycles, which is critical to synchronizing sexual maturation. However, regulating the conditions of a whole room has limitations, especially if experiments require being able to change culturing conditions. Here we present scalable and flexible culture methods that provide ability to control the environmental conditions, and have a multi-purpose culture space. We provide a closed setup shelving design with proper light conditions necessary for P. dumerilii to mature. We also implemented a standardized method of feeding P. dumerilii cultures with powdered spirulina which relieves the ambiguity associated with using frozen spinach, and helps standardize nutrition conditions across experiments and across different labs. By using these methods, we were able to raise mature P. dumerilii, capable of spawning and producing viable embryos for experimentation and replenishing culture populations. These methods will allow for the further accessibility of P. dumerilii as a model system, and they can be adapted for other aquatic organisms.
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Affiliation(s)
- Emily Kuehn
- Marine Biological Laboratory, Woods Hole, Massachusetts, United States of America
| | | | - Jerome Girard
- Marine Biological Laboratory, Woods Hole, Massachusetts, United States of America
| | | | - B. Duygu Özpolat
- Marine Biological Laboratory, Woods Hole, Massachusetts, United States of America
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Vopalensky P, Tosches MA, Achim K, Handberg-Thorsager M, Arendt D. From spiral cleavage to bilateral symmetry: the developmental cell lineage of the annelid brain. BMC Biol 2019; 17:81. [PMID: 31640768 PMCID: PMC6805352 DOI: 10.1186/s12915-019-0705-x] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2019] [Accepted: 10/01/2019] [Indexed: 11/15/2022] Open
Abstract
BACKGROUND During early development, patterns of cell division-embryonic cleavage-accompany the gradual restriction of blastomeres to specific cell fates. In Spiralia, which include annelids, mollusks, and flatworms, "spiral cleavage" produces a highly stereotypic, spiral-like arrangement of blastomeres and swimming trochophore-type larvae with rotational (spiral) symmetry. However, starting at larval stages, spiralian larvae acquire elements of bilateral symmetry, before they metamorphose into fully bilateral juveniles. How this spiral-to-bilateral transition occurs is not known and is especially puzzling for the early differentiating brain and head sensory organs, which emerge directly from the spiral cleavage pattern. Here we present the developmental cell lineage of the Platynereis larval episphere. RESULTS Live-imaging recordings from the zygote to the mid-trochophore stage (~ 30 hpf) of the larval episphere of the marine annelid Platynereis dumerilii reveal highly stereotypical development and an invariant cell lineage of early differentiating cell types. The larval brain and head sensory organs develop from 11 pairs of bilateral founders, each giving rise to identical clones on the right and left body sides. Relating the origin of each bilateral founder pair back to the spiral cleavage pattern, we uncover highly divergent origins: while some founder pairs originate from corresponding cells in the spiralian lineage on each body side, others originate from non-corresponding cells, and yet others derive from a single cell within one quadrant. Integrating lineage and gene expression data for several embryonic and larval stages, we find that the conserved head patterning genes otx and six3 are expressed in bilateral founders representing divergent lineage histories and giving rise to early differentiating cholinergic neurons and head sensory organs, respectively. CONCLUSIONS We present the complete developmental cell lineage of the Platynereis larval episphere, and thus the first comprehensive account of the spiral-to-bilateral transition in a developing spiralian. The bilateral symmetry of the head emerges from pairs of bilateral founders, similar to the trunk; however, the head founders are more numerous and show striking left-right asymmetries in lineage behavior that we relate to differential gene expression.
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Affiliation(s)
- Pavel Vopalensky
- Developmental Biology Unit, European Molecular Biology Laboratory, Meyerhofstraße 1, 69117, Heidelberg, Germany
| | - Maria Antonietta Tosches
- Developmental Biology Unit, European Molecular Biology Laboratory, Meyerhofstraße 1, 69117, Heidelberg, Germany
| | - Kaia Achim
- Developmental Biology Unit, European Molecular Biology Laboratory, Meyerhofstraße 1, 69117, Heidelberg, Germany
| | - Mette Handberg-Thorsager
- Developmental Biology Unit, European Molecular Biology Laboratory, Meyerhofstraße 1, 69117, Heidelberg, Germany
- Max Planck Institute of Molecular Cell Biology and Genetics, Pfotenhauerstraße 108, Dresden, 01307, Germany
| | - Detlev Arendt
- Developmental Biology Unit, European Molecular Biology Laboratory, Meyerhofstraße 1, 69117, Heidelberg, Germany.
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A GABAergic Maf-expressing interneuron subset regulates the speed of locomotion in Drosophila. Nat Commun 2019; 10:4796. [PMID: 31641138 PMCID: PMC6805931 DOI: 10.1038/s41467-019-12693-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2018] [Accepted: 09/23/2019] [Indexed: 12/19/2022] Open
Abstract
Interneurons (INs) coordinate motoneuron activity to generate appropriate patterns of muscle contractions, providing animals with the ability to adjust their body posture and to move over a range of speeds. In Drosophila larvae several IN subtypes have been morphologically described and their function well documented. However, the general lack of molecular characterization of those INs prevents the identification of evolutionary counterparts in other animals, limiting our understanding of the principles underlying neuronal circuit organization and function. Here we characterize a restricted subset of neurons in the nerve cord expressing the Maf transcription factor Traffic Jam (TJ). We found that TJ+ neurons are highly diverse and selective activation of these different subtypes disrupts larval body posture and induces specific locomotor behaviors. Finally, we show that a small subset of TJ+ GABAergic INs, singled out by the expression of a unique transcription factors code, controls larval crawling speed. Spinal interneurons (IN) coordinate motoneuron activity to modulate locomotion behavior. Here, the authors characterize a subset of IN subtypes expressing the Maf transcription factor Traffic Jam (TJ) and report the distinct effects of their activation on body posture and locomotion in Drosophila larvae.
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Yurchenko OV, Savelieva AV, Kolotuchina NK, Voronezhskaya EE, Dyachuk VA. Peripheral sensory neurons govern development of the nervous system in bivalve larvae. EvoDevo 2019; 10:22. [PMID: 31528326 PMCID: PMC6743156 DOI: 10.1186/s13227-019-0133-6] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2018] [Accepted: 08/21/2019] [Indexed: 12/15/2022] Open
Abstract
Recent findings regarding early lophotrochozoan development have altered the conventional model of neurogenesis and revealed that peripheral sensory elements play a key role in the initial organization of the larval nervous system. Here, we describe the main neurogenetic events in bivalve mollusks in comparison with other Lophotrochozoa, emphasizing a novel role for early neurons in establishing larval nervous systems and speculating about the morphogenetic function of the apical organ. We demonstrate that during bivalve development, peripheral sensory neurons utilizing various transmitters differentiate before the apical organ emerges. The first neurons and their neurites serve as a scaffold for the development of the nervous system. During veliger stage, cerebral, pleural, and visceral ganglia form along the lateral (visceral) nerve cords in anterior-to-posterior axis. The pedal ganglia and corresponding ventral (pedal) nerve cords develop much later, after larval settlement and metamorphosis. Pharmacological abolishment of the serotonin gradient within the larval body disrupts the navigation of "pioneer" axons resulting in malformation of the whole nervous system architecture. Comparative morphological data on neurogenetic events in bivalve mollusks shed new light on the origin of the nervous system, mechanisms of early axon navigation, and sequence of the tetraneurous nervous system formation. Furthermore, this information improves our understanding of the basic nervous system architecture in larval Bivalvia and Mollusca.
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Affiliation(s)
- Olga V. Yurchenko
- National Scientific Center of Marine Biology, Far Eastern Branch, Russian Academy of Sciences, Vladivostok, 690041 Russia
| | - Anna V. Savelieva
- National Scientific Center of Marine Biology, Far Eastern Branch, Russian Academy of Sciences, Vladivostok, 690041 Russia
| | - Natalia K. Kolotuchina
- National Scientific Center of Marine Biology, Far Eastern Branch, Russian Academy of Sciences, Vladivostok, 690041 Russia
| | - Elena E. Voronezhskaya
- N.K. Koltsov Institute of Developmental Biology, Russian Academy of Sciences, Moscow, 119991 Russia
| | - Vyacheslav A. Dyachuk
- National Scientific Center of Marine Biology, Far Eastern Branch, Russian Academy of Sciences, Vladivostok, 690041 Russia
- Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden
- Department of Nanophotonics and Metamaterials, ITMO University, St. Petersburg, Russia
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28
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Catela C, Kratsios P. Transcriptional mechanisms of motor neuron development in vertebrates and invertebrates. Dev Biol 2019; 475:193-204. [PMID: 31479648 DOI: 10.1016/j.ydbio.2019.08.022] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2017] [Revised: 07/08/2019] [Accepted: 08/29/2019] [Indexed: 02/04/2023]
Abstract
Across phylogeny, motor neurons (MNs) represent a single but often remarkably diverse neuronal class composed of a multitude of subtypes required for vital behaviors, such as eating and locomotion. Over the past decades, seminal studies in multiple model organisms have advanced our molecular understanding of the early steps of MN development, such as progenitor specification and acquisition of MN subtype identity, by revealing key roles for several evolutionarily conserved transcription factors. However, very little is known about the molecular strategies that allow distinct MN subtypes to maintain their identity- and function-defining features during the late steps of development and postnatal life. Here, we provide an overview of invertebrate and vertebrate studies on transcription factor-based strategies that control early and late steps of MN development, aiming to highlight evolutionarily conserved gene regulatory principles necessary for establishment and maintenance of neuronal identity.
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Affiliation(s)
- Catarina Catela
- Department of Neurobiology, University of Chicago, Chicago, IL, 60637, USA; The Grossman Institute for Neuroscience, Quantitative Biology and Human Behavior, The University of Chicago, Chicago, IL, USA
| | - Paschalis Kratsios
- Department of Neurobiology, University of Chicago, Chicago, IL, 60637, USA; The Grossman Institute for Neuroscience, Quantitative Biology and Human Behavior, The University of Chicago, Chicago, IL, USA.
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29
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Barkan CL, Zornik E. Feedback to the future: motor neuron contributions to central pattern generator function. ACTA ACUST UNITED AC 2019; 222:222/16/jeb193318. [PMID: 31420449 DOI: 10.1242/jeb.193318] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Motor behaviors depend on neural signals in the brain. Regardless of where in the brain behavior patterns arise, the central nervous system sends projections to motor neurons, which in turn project to and control temporally appropriate muscle contractions; thus, motor neurons are traditionally considered the last relay from the central nervous system to muscles. However, in an array of species and motor systems, an accumulating body of evidence supports a more complex role of motor neurons in pattern generation. These studies suggest that motor neurons not only relay motor patterns to the periphery, but directly contribute to pattern generation by providing feedback to upstream circuitry. In spinal and hindbrain circuits in a variety of animals - including flies, worms, leeches, crustaceans, rodents, birds, fish, amphibians and mammals - studies have indicated a crucial role for motor neuron feedback in maintaining normal behavior patterns dictated by the activity of a central pattern generator. Hence, in this Review, we discuss literature examining the role of motor neuron feedback across many taxa and behaviors, and set out to determine the prevalence of motor neuron participation in motor circuits.
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Affiliation(s)
| | - Erik Zornik
- Biology Department, Reed College, Portland, OR 97202, USA
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30
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Callahan RA, Roberts R, Sengupta M, Kimura Y, Higashijima SI, Bagnall MW. Spinal V2b neurons reveal a role for ipsilateral inhibition in speed control. eLife 2019; 8:e47837. [PMID: 31355747 PMCID: PMC6701946 DOI: 10.7554/elife.47837] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2019] [Accepted: 07/26/2019] [Indexed: 12/22/2022] Open
Abstract
The spinal cord contains a diverse array of interneurons that govern motor output. Traditionally, models of spinal circuits have emphasized the role of inhibition in enforcing reciprocal alternation between left and right sides or flexors and extensors. However, recent work has shown that inhibition also increases coincident with excitation during contraction. Here, using larval zebrafish, we investigate the V2b (Gata3+) class of neurons, which contribute to flexor-extensor alternation but are otherwise poorly understood. Using newly generated transgenic lines we define two stable subclasses with distinct neurotransmitter and morphological properties. These V2b subclasses synapse directly onto motor neurons with differential targeting to speed-specific circuits. In vivo, optogenetic manipulation of V2b activity modulates locomotor frequency: suppressing V2b neurons elicits faster locomotion, whereas activating V2b neurons slows locomotion. We conclude that V2b neurons serve as a brake on axial motor circuits. Together, these results indicate a role for ipsilateral inhibition in speed control.
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Affiliation(s)
- Rebecca A Callahan
- Department of NeuroscienceWashington University School of MedicineSt LouisUnited States
| | - Richard Roberts
- Department of NeuroscienceWashington University School of MedicineSt LouisUnited States
| | - Mohini Sengupta
- Department of NeuroscienceWashington University School of MedicineSt LouisUnited States
| | | | | | - Martha W Bagnall
- Department of NeuroscienceWashington University School of MedicineSt LouisUnited States
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31
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Zeng T, Dai H. Single-Cell RNA Sequencing-Based Computational Analysis to Describe Disease Heterogeneity. Front Genet 2019; 10:629. [PMID: 31354786 PMCID: PMC6640157 DOI: 10.3389/fgene.2019.00629] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2019] [Accepted: 06/17/2019] [Indexed: 12/25/2022] Open
Abstract
The trillions of cells in the human body can be viewed as elementary but essential biological units that achieve different body states, but the low resolution of previous cell isolation and measurement approaches limits our understanding of the cell-specific molecular profiles. The recent establishment and rapid growth of single-cell sequencing technology has facilitated the identification of molecular profiles of heterogeneous cells, especially on the transcription level of single cells [single-cell RNA sequencing (scRNA-seq)]. As a novel method, the robustness of scRNA-seq under changing conditions will determine its practical potential in major research programs and clinical applications. In this review, we first briefly presented the scRNA-seq-related methods from the point of view of experiments and computation. Then, we compared several state-of-the-art scRNA-seq analysis frameworks mainly by analyzing their performance robustness on independent scRNA-seq datasets for the same complex disease. Finally, we elaborated on our hypothesis on consensus scRNA-seq analysis and summarized the potential indicative and predictive roles of individual cells in understanding disease heterogeneity by single-cell technologies.
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Affiliation(s)
- Tao Zeng
- Key Laboratory of Systems Biology, Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, Shanghai, China
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32
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Williams EA, Jékely G. Neuronal cell types in the annelid Platynereis dumerilii. Curr Opin Neurobiol 2019; 56:106-116. [DOI: 10.1016/j.conb.2018.12.008] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2018] [Revised: 12/14/2018] [Accepted: 12/17/2018] [Indexed: 02/08/2023]
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Abstract
How the centralized nervous systems of animals evolved remains unclear. Do the nerve cords found at various positions in the worm-shaped bodies of bilaterian animals have a common or an independent evolutionary origin? New comparative data fuel this long-standing debate.
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34
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Chartier TF, Deschamps J, Dürichen W, Jékely G, Arendt D. Whole-head recording of chemosensory activity in the marine annelid Platynereis dumerilii. Open Biol 2018; 8:180139. [PMID: 30381362 PMCID: PMC6223215 DOI: 10.1098/rsob.180139] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2018] [Accepted: 10/08/2018] [Indexed: 01/13/2023] Open
Abstract
Chemical detection is key to various behaviours in both marine and terrestrial animals. Marine species, though highly diverse, have been underrepresented so far in studies on chemosensory systems, and our knowledge mostly concerns the detection of airborne cues. A broader comparative approach is therefore desirable. Marine annelid worms with their rich behavioural repertoire represent attractive models for chemosensation. Here, we study the marine worm Platynereis dumerilii to provide the first comprehensive investigation of head chemosensory organ physiology in an annelid. By combining microfluidics and calcium imaging, we record neuronal activity in the entire head of early juveniles upon chemical stimulation. We find that Platynereis uses four types of organs to detect stimuli such as alcohols, esters, amino acids and sugars. Antennae are the main chemosensory organs, compared to the more differentially responding nuchal organs or palps. We report chemically evoked activity in possible downstream brain regions including the mushroom bodies (MBs), which are anatomically and molecularly similar to insect MBs. We conclude that chemosensation is a major sensory modality for marine annelids and propose early Platynereis juveniles as a model to study annelid chemosensory systems.
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Affiliation(s)
- Thomas F Chartier
- Developmental Biology Unit, European Molecular Biology Laboratory, Meyerhofstraße 1, 69117 Heidelberg, Germany
| | - Joran Deschamps
- Cell Biology and Biophysics Unit, European Molecular Biology Laboratory, Meyerhofstraße 1, 69117 Heidelberg, Germany
| | - Wiebke Dürichen
- Developmental Biology Unit, European Molecular Biology Laboratory, Meyerhofstraße 1, 69117 Heidelberg, Germany
| | - Gáspár Jékely
- Living Systems Institute, University of Exeter, Stocker Road, Exeter EX4 4QD, UK
| | - Detlev Arendt
- Developmental Biology Unit, European Molecular Biology Laboratory, Meyerhofstraße 1, 69117 Heidelberg, Germany
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35
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Helm C, Beckers P, Bartolomaeus T, Drukewitz SH, Kourtesis I, Weigert A, Purschke G, Worsaae K, Struck TH, Bleidorn C. Convergent evolution of the ladder-like ventral nerve cord in Annelida. Front Zool 2018; 15:36. [PMID: 30275868 PMCID: PMC6161469 DOI: 10.1186/s12983-018-0280-y] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2018] [Accepted: 09/04/2018] [Indexed: 12/15/2022] Open
Abstract
BACKGROUND A median, segmented, annelid nerve cord has repeatedly been compared to the arthropod and vertebrate nerve cords and became the most used textbook representation of the annelid nervous system. Recent phylogenomic analyses, however, challenge the hypothesis that a subepidermal rope-ladder-like ventral nerve cord (VNC) composed of a paired serial chain of ganglia and somata-free connectives represents either a plesiomorphic or a typical condition in annelids. RESULTS Using a comparative approach by combining phylogenomic analyses with morphological methods (immunohistochemistry and CLSM, histology and TEM), we compiled a comprehensive dataset to reconstruct the evolution of the annelid VNC. Our phylogenomic analyses generally support previous topologies. However, the so far hard-to-place Apistobranchidae and Psammodrilidae are now incorporated among the basally branching annelids with high support. Based on this topology we reconstruct an intraepidermal VNC as the ancestral state in Annelida. Thus, a subepidermal ladder-like nerve cord clearly represents a derived condition. CONCLUSIONS Based on the presented data, a ladder-like appearance of the ventral nerve cord evolved repeatedly, and independently of the transition from an intraepidermal to a subepidermal cord during annelid evolution. Our investigations thereby propose an alternative set of neuroanatomical characteristics for the last common ancestor of Annelida or perhaps even Spiralia.
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Affiliation(s)
- Conrad Helm
- Animal Evolution and Biodiversity, Georg-August-University Göttingen, 37073 Göttingen, Germany
| | - Patrick Beckers
- Institute of Evolutionary Biology and Ecology, University of Bonn, 53121 Bonn, Germany
| | - Thomas Bartolomaeus
- Institute of Evolutionary Biology and Ecology, University of Bonn, 53121 Bonn, Germany
| | | | - Ioannis Kourtesis
- Animal Evolution and Biodiversity, Georg-August-University Göttingen, 37073 Göttingen, Germany
| | - Anne Weigert
- Department of Evolutionary Genetics, Max Planck Institute for Evolutionary Anthropology, 04103 Leipzig, Germany
| | - Günter Purschke
- Department of Developmental Biology and Zoology, University of Osnabrück, 49069 Osnabrück, Germany
| | - Katrine Worsaae
- Department of Biology, University of Copenhagen, 2100 Copenhagen, Denmark
| | - Torsten H. Struck
- Frontiers in Evolutionary Zoology, Natural History Museum, University of Oslo, P.O. Box 1172, Blindern, NO-0318 Oslo, Norway
| | - Christoph Bleidorn
- Animal Evolution and Biodiversity, Georg-August-University Göttingen, 37073 Göttingen, Germany
- German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig, Deutscher Platz 5e, 04103 Leipzig, Germany
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Chou HC, Acevedo-Luna N, Kuhlman JA, Schneider SQ. PdumBase: a transcriptome database and research tool for Platynereis dumerilii and early development of other metazoans. BMC Genomics 2018; 19:618. [PMID: 30115014 PMCID: PMC6097317 DOI: 10.1186/s12864-018-4987-0] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2018] [Accepted: 07/31/2018] [Indexed: 12/22/2022] Open
Abstract
BACKGROUND The marine polychaete annelid Platynereis dumerilii has recently emerged as a prominent organism for the study of development, evolution, stem cells, regeneration, marine ecology, chronobiology and neurobiology within metazoans. Its phylogenetic position within the spiralian/ lophotrochozoan clade, the comparatively high conservation of ancestral features in the Platynereis genome, and experimental access to any stage within its life cycle, make Platynereis an important model for elucidating the complex regulatory and functional molecular mechanisms governing early development, later organogenesis, and various features of its larval and adult life. High resolution RNA-seq gene expression data obtained from specific developmental stages can be used to dissect early developmental mechanisms. However, the potential for discovery of these mechanisms relies on tools to search, retrieve, and compare genome-wide information within Platynereis, and across other metazoan taxa. RESULTS To facilitate exploration and discovery by the broader scientific community, we have developed a web-based, searchable online research tool, PdumBase, featuring the first comprehensive transcriptome database for Platynereis dumerilii during early stages of development (2 h ~ 14 h). Our database also includes additional stages over the P. dumerilii life cycle and provides access to the expression data of 17,213 genes (31,806 transcripts) along with annotation information sourced from Swiss-Prot, Gene Ontology, KEGG pathways, Pfam domains, TmHMM, SingleP, and EggNOG orthology. Expression data for each gene includes the stage, the normalized FPKM, the raw read counts, and information that can be leveraged for statistical analyses of differential gene expression and the construction of genome-wide co-expression networks. In addition, PdumBase offers early stage transcriptome expression data from five further species as a valuable resource for investigators interested in comparing early development in different organisms. To understand conservation of Platynereis gene models and to validate gene annotation, most Platynereis gene models include a comprehensive phylogenetic analysis across 18 species representing diverse metazoan taxa. CONCLUSIONS PdumBase represents the first online resource for the early developmental transcriptome of Platynereis dumerilii. It serves as a research platform for discovery and exploration of gene expression during early stages, throughout the Platynereis life cycle, and enables comparison to other model organisms. PdumBase is freely available at http://pdumbase.gdcb.iastate.edu .
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Affiliation(s)
- Hsien-Chao Chou
- Department of Genetics, Developmental and Cell Biology, Iowa State University, 503 Science Hall II, Ames, IA 50011 USA
- Present address: Center for Cancer Research, National Institutes of Health, Rockville, MD 20894 USA
| | - Natalia Acevedo-Luna
- Department of Genetics, Developmental and Cell Biology, Iowa State University, 503 Science Hall II, Ames, IA 50011 USA
| | - Julie A. Kuhlman
- Department of Genetics, Developmental and Cell Biology, Iowa State University, 503 Science Hall II, Ames, IA 50011 USA
| | - Stephan Q. Schneider
- Department of Genetics, Developmental and Cell Biology, Iowa State University, 503 Science Hall II, Ames, IA 50011 USA
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Moroz LL. NeuroSystematics and Periodic System of Neurons: Model vs Reference Species at Single-Cell Resolution. ACS Chem Neurosci 2018; 9:1884-1903. [PMID: 29989789 DOI: 10.1021/acschemneuro.8b00100] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
There is more than one way to develop neuronal complexity, and animals frequently use different molecular toolkits to achieve similar functional outcomes (=convergent evolution). Neurons are different not only because they have different functions, but also because neurons and circuits have different genealogies, and perhaps independent origins at the broadest scale from ctenophores and cnidarians to cephalopods and primates. By combining modern phylogenomics, single-neuron sequencing (scRNA-seq), machine learning, single-cell proteomics, and metabolomic across Metazoa, it is possible to reconstruct the evolutionary histories of neurons tracing them to ancestral secretory cells. Comparative data suggest that neurons, and perhaps synapses, evolved at least 2-3 times (in ctenophore, cnidarian and bilateral lineages) during ∼600 million years of animal evolution. There were also several independent events of the nervous system centralization either from a common bilateral/cnidarian ancestor without the bona fide neurons or from the urbilaterian with diffuse, nerve-net type nervous system. From the evolutionary standpoint, (i) a neuron should be viewed as a functional rather than a genetic character, and (ii) any given neural system might be chimeric and composed of different cell lineages with distinct origins and evolutionary histories. The identification of distant neural homologies or examples of convergent evolution among 34 phyla will not only allow the reconstruction of neural systems' evolution but together with single-cell "omic" approaches the proposed synthesis would lead to the "Periodic System of Neurons" with predictive power for neuronal phenotypes and plasticity. Such a phylogenetic classification framework of Neuronal Systematics (NeuroSystematics) might be a conceptual analog of the Periodic System of Chemical Elements. scRNA-seq profiling of all neurons in an entire brain or Brain-seq is now fully achievable in many nontraditional reference species across the entire animal kingdom. Arguably, marine animals are the most suitable for the proposed tasks because the world oceans represent the greatest taxonomic and body-plan diversity.
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Affiliation(s)
- Leonid L. Moroz
- Department of Neuroscience and McKnight Brain Institute, University of Florida, 1149 Newell Drive, Gainesville, Florida 32611, United States
- Whitney Laboratory for Marine Bioscience, University of Florida, 9505 Ocean Shore Blvd., St. Augustine, Florida 32080, United States
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Gene regulatory networks and network models in development and evolution. Proc Natl Acad Sci U S A 2018; 114:5782-5783. [PMID: 28584088 DOI: 10.1073/pnas.1610618114] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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Achim K, Eling N, Vergara HM, Bertucci PY, Musser J, Vopalensky P, Brunet T, Collier P, Benes V, Marioni JC, Arendt D. Whole-Body Single-Cell Sequencing Reveals Transcriptional Domains in the Annelid Larval Body. Mol Biol Evol 2018; 35:1047-1062. [PMID: 29373712 PMCID: PMC5913682 DOI: 10.1093/molbev/msx336] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Animal bodies comprise diverse arrays of cells. To characterize cellular identities across an entire body, we have compared the transcriptomes of single cells randomly picked from dissociated whole larvae of the marine annelid Platynereis dumerilii. We identify five transcriptionally distinct groups of differentiated cells, each expressing a unique set of transcription factors and effector genes that implement cellular phenotypes. Spatial mapping of cells into a cellular expression atlas, and wholemount in situ hybridization of group-specific genes reveals spatially coherent transcriptional domains in the larval body, comprising, for example, apical sensory-neurosecretory cells versus neural/epidermal surface cells. These domains represent new, basic subdivisions of the annelid body based entirely on differential gene expression, and are composed of multiple, transcriptionally similar cell types. They do not represent clonal domains, as revealed by developmental lineage analysis. We propose that the transcriptional domains that subdivide the annelid larval body represent families of related cell types that have arisen by evolutionary diversification. Their possible evolutionary conservation makes them a promising tool for evo-devo research.
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Affiliation(s)
- Kaia Achim
- Developmental Biology Unit, European Molecular Biology Laboratory, Heidelberg, Germany
| | - Nils Eling
- EMBL-European Bioinformatics Institute (EMBL-EBI), Wellcome Genome Campus, Cambridge, United Kingdom
- Cancer Research UK Cambridge Institute, University of Cambridge, Cambridge, United Kingdom
| | | | - Paola Yanina Bertucci
- Developmental Biology Unit, European Molecular Biology Laboratory, Heidelberg, Germany
| | - Jacob Musser
- Developmental Biology Unit, European Molecular Biology Laboratory, Heidelberg, Germany
| | - Pavel Vopalensky
- Developmental Biology Unit, European Molecular Biology Laboratory, Heidelberg, Germany
| | - Thibaut Brunet
- Developmental Biology Unit, European Molecular Biology Laboratory, Heidelberg, Germany
| | - Paul Collier
- Genomics Core Facility, European Molecular Biology Laboratory, Heidelberg, Germany
| | - Vladimir Benes
- Genomics Core Facility, European Molecular Biology Laboratory, Heidelberg, Germany
| | - John C Marioni
- EMBL-European Bioinformatics Institute (EMBL-EBI), Wellcome Genome Campus, Cambridge, United Kingdom
- Cancer Research UK Cambridge Institute, University of Cambridge, Cambridge, United Kingdom
- Wellcome Trust Sanger Institute, Wellcome Genome Campus, Cambridge, United Kingdom
| | - Detlev Arendt
- Developmental Biology Unit, European Molecular Biology Laboratory, Heidelberg, Germany
- Centre for Organismal Studies, University of Heidelberg, Heidelberg, Germany
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Yurchenko OV, Skiteva OI, Voronezhskaya EE, Dyachuk VA. Nervous system development in the Pacific oyster, Crassostrea gigas (Mollusca: Bivalvia). Front Zool 2018; 15:10. [PMID: 29681988 PMCID: PMC5896133 DOI: 10.1186/s12983-018-0259-8] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2017] [Accepted: 03/20/2018] [Indexed: 01/26/2023] Open
Abstract
Background Bivalves comprise a large, highly diverse taxon of invertebrate species. Developmental studies of neurogenesis among species of Bivalvia are limited. Due to a lack of neurogenesis information, it is difficult to infer a ground pattern for Bivalvia. To provide more comprehensive morphogenetic data on bivalve molluscs and relationships among molluscan clades, we investigated neurogenesis in the Pacific oyster, Crassostrea gigas, from the appearance of the first sensory cells to the formation of the larval ganglionic nervous system by co-immunocytochemistry of the neuronal markers FMRFamide or 5-HT and vesicular acetylcholine transporter (VAChT). Results Neurogenesis begins with the emergence of the apical serotonin-immunoreactive (5-HT-ir) sensory cells and paired sensory posttrochal dorsal and ventral FMRFamide-immunoreactive (FMRFamide-ir) cells at the early trochophore stage. Later, at the early veliger stage, the apical organ (AO) includes 5-HT-ir, FMRFamide-ir, and VAChT-ir cells. At the same stage, VAChT-ir cells appear in the posterior region of larvae and send axons towards the AO. Thus, FMRFamide-ir neurites and VAChT-ir processes form scaffolds for longitudinal neurite bundles develop into the paired ventral nerve cords (VNC). Later-appearing axons from the AO/CG neurons join the neurite bundles comprising the VNC. All larval ganglia appear along the VNC as paired or fused (epiathroid) clusters in late veliger and pediveliger larvae. We observed the transformation of the AO into the cerebral ganglia, which abundantly innervated the velum, and the transformation of ventral neurons into the pedal ganglia, innervating the foot, gills, and anterior adductor muscle. The visceral ganglia appear last in the pediveliger oyster and innervate the visceral mass and posterior adductor of premetamorphic larvae. In addition, a local FMRFamide-ir network was detected in the digestive system of pediveliger larvae. We identified VAChT-ir nervous elements in oyster larvae, which have not been observed previously in molluscs. Finally, we performed a morphology-based comparative analysis of neuronal structures among bivalve, conchiferan, and aculiferan species. Conclusions We described the development of the nervous system during the larval development in Crassostrea gigas. These data greatly advance the currently limited understanding of neurodevelopment in bivalves and mollusks, which has hampered the generation of a ground pattern reconstruction of the last common ancestor of Mollusca. Our morphological data support phylogenomic data indicating a closer Bivalvia-Gastropoda sister group relationship than the Bivalvia-Scaphopoda (Diasoma) group relationship. Electronic supplementary material The online version of this article (10.1186/s12983-018-0259-8) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Olga V Yurchenko
- 1National Scientific Center of Marine Biology, Far Eastern Branch, Russian Academy of Sciences, Vladivostok, 690041 Russia
| | - Olga I Skiteva
- 2Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden
| | - Elena E Voronezhskaya
- 3N.K. Koltzov Institute of Developmental Biology, Russian Academy of Sciences, Moscow, 119991 Russia.,Department of Pathology, Cell biology and Biochemistry, Central Tuberculosis Research Institute, Moscow, Russian Federation
| | - Vyacheslav A Dyachuk
- 1National Scientific Center of Marine Biology, Far Eastern Branch, Russian Academy of Sciences, Vladivostok, 690041 Russia.,5Far Eastern Federal University, Vladivostok, 690950 Russia.,6Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden
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Abstract
Every cell within living organisms actively maintains an intracellular Na+ concentration that is 10-12 times lower than the extracellular concentration. The cells then utilize this transmembrane Na+ concentration gradient as a driving force to produce electrical signals, sometimes in the form of action potentials. The protein family comprising voltage-gated sodium channels (NaVs) is essential for such signaling and enables cells to change their status in a regenerative manner and to rapidly communicate with one another. NaVs were first predicted in squid and were later identified through molecular biology in the electric eel. Since then, these proteins have been discovered in organisms ranging from bacteria to humans. Recent research has succeeded in decoding the amino acid sequences of a wide variety of NaV family members, as well as the three-dimensional structures of some. These studies and others have uncovered several of the major steps in the functional and structural transition of NaV proteins that has occurred along the course of the evolutionary history of organisms. Here we present an overview of the molecular evolutionary innovations that established present-day NaV α subunits and discuss their contribution to the evolutionary changes in animal bodies.
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Affiliation(s)
- Atsuo Nishino
- Department of Biology, Faculty of Agriculture and Life Science, Hirosaki University, Hirosaki, Aomori, Japan.
| | - Yasushi Okamura
- Integrative Physiology, Graduate School of Medicine, Osaka University, Suita, Osaka, Japan
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Abstract
It has been hypothesized that a condensed nervous system with a medial ventral nerve cord is an ancestral character of Bilateria. The presence of similar dorsoventral molecular patterns along the nerve cords of vertebrates, flies, and an annelid has been interpreted as support for this scenario. Whether these similarities are generally found across the diversity of bilaterian neuroanatomies is unclear, and thus the evolutionary history of the nervous system is still contentious. Here we study representatives of Xenacoelomorpha, Rotifera, Nemertea, Brachiopoda, and Annelida to assess the conservation of the dorsoventral nerve cord patterning. None of the studied species show a conserved dorsoventral molecular regionalization of their nerve cords, not even the annelid Owenia fusiformis, whose trunk neuroanatomy parallels that of vertebrates and flies. Our findings restrict the use of molecular patterns to explain nervous system evolution, and suggest that the similarities in dorsoventral patterning and trunk neuroanatomies evolved independently in Bilateria.
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Ventimiglia D, Bargmann CI. Diverse modes of synaptic signaling, regulation, and plasticity distinguish two classes of C. elegans glutamatergic neurons. eLife 2017; 6:e31234. [PMID: 29160768 PMCID: PMC5705214 DOI: 10.7554/elife.31234] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2017] [Accepted: 11/20/2017] [Indexed: 11/13/2022] Open
Abstract
Synaptic vesicle release properties vary between neuronal cell types, but in most cases the molecular basis of this heterogeneity is unknown. Here, we compare in vivo synaptic properties of two neuronal classes in the C. elegans central nervous system, using VGLUT-pHluorin to monitor synaptic vesicle exocytosis and retrieval in intact animals. We show that the glutamatergic sensory neurons AWCON and ASH have distinct synaptic dynamics associated with tonic and phasic synaptic properties, respectively. Exocytosis in ASH and AWCON is differentially affected by SNARE-complex regulators that are present in both neurons: phasic ASH release is strongly dependent on UNC-13, whereas tonic AWCON release relies upon UNC-18 and on the protein kinase C homolog PKC-1. Strong stimuli that elicit high calcium levels increase exocytosis and retrieval rates in AWCON, generating distinct tonic and evoked synaptic modes. These results highlight the differential deployment of shared presynaptic proteins in neuronal cell type-specific functions.
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Affiliation(s)
- Donovan Ventimiglia
- Lulu and Anthony Wang Laboratory of Neural Circuits and BehaviorThe Rockefeller UniversityNew YorkUnited States
| | - Cornelia I Bargmann
- Lulu and Anthony Wang Laboratory of Neural Circuits and BehaviorThe Rockefeller UniversityNew YorkUnited States
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Abstract
The recent flood of single-cell data not only boosts our knowledge of cells and cell types, but also provides new insight into development and evolution from a cellular perspective. For example, assaying the genomes of multiple cells during development reveals developmental lineage trees-the kinship lineage-whereas cellular transcriptomes inform us about the regulatory state of cells and their gradual restriction in potency-the Waddington lineage. Beyond that, the comparison of single-cell data across species allows evolutionary changes to be tracked at all stages of development from the zygote, via different kinds of stem cells, to the differentiating cells. We discuss recent insights into the evolution of stem cells and initial attempts to reconstruct the evolutionary cell type tree of the mammalian forebrain, for example, by the comparative analysis of neuron types in the mesencephalic floor. These studies illustrate the immense potential of single-cell genomics to open up a new era in developmental and evolutionary research.
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Affiliation(s)
- John C Marioni
- EMBL-European Bioinformatics Institute, Wellcome Genome Campus, Cambridge CB10 1SD, United Kingdom;
- Cancer Research UK Cambridge Institute, University of Cambridge, Cambridge CB2 0RE, United Kingdom
- Wellcome Trust Sanger Institute, Wellcome Genome Campus, Cambridge CB10 1SA, United Kingdom
| | - Detlev Arendt
- Developmental Biology Unit, EMBL, 69117 Heidelberg, Germany;
- Centre for Organismal Studies, University of Heidelberg, 69120 Heidelberg, Germany
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