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Liang Y, Carrillo-Baltodano AM, Martín-Durán JM. Emerging trends in the study of spiralian larvae. Evol Dev 2024; 26:e12459. [PMID: 37787615 DOI: 10.1111/ede.12459] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2023] [Revised: 09/11/2023] [Accepted: 09/13/2023] [Indexed: 10/04/2023]
Abstract
Many animals undergo indirect development, where their embryogenesis produces an intermediate life stage, or larva, that is often free-living and later metamorphoses into an adult. As their adult counterparts, larvae can have unique and diverse morphologies and occupy various ecological niches. Given their broad phylogenetic distribution, larvae have been central to hypotheses about animal evolution. However, the evolution of these intermediate forms and the developmental mechanisms diversifying animal life cycles are still debated. This review focuses on Spiralia, a large and diverse clade of bilaterally symmetrical animals with a fascinating array of larval forms, most notably the archetypical trochophore larva. We explore how classic research and modern advances have improved our understanding of spiralian larvae, their development, and evolution. Specifically, we examine three morphological features of spiralian larvae: the anterior neural system, the ciliary bands, and the posterior hyposphere. The combination of molecular and developmental evidence with modern high-throughput techniques, such as comparative genomics, single-cell transcriptomics, and epigenomics, is a promising strategy that will lead to new testable hypotheses about the mechanisms behind the evolution of larvae and life cycles in Spiralia and animals in general. We predict that the increasing number of available genomes for Spiralia and the optimization of genome-wide and single-cell approaches will unlock the study of many emerging spiralian taxa, transforming our views of the evolution of this animal group and their larvae.
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Affiliation(s)
- Yan Liang
- School of Biological and Behavioural Sciences, Queen Mary University of London, London, UK
| | | | - José M Martín-Durán
- School of Biological and Behavioural Sciences, Queen Mary University of London, London, UK
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2
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Zhang X, Tong X, Tang X, Yang Y, Zhang L, Zhan X, Zhang X. Behavioral toxicity of TDCPP in marine zooplankton: Evidence from feeding and swimming responses, molecular dynamics and metabolomics of rotifers. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 921:170864. [PMID: 38401740 DOI: 10.1016/j.scitotenv.2024.170864] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/08/2023] [Revised: 01/20/2024] [Accepted: 02/07/2024] [Indexed: 02/26/2024]
Abstract
As new organic flame retardants, chlorinated organophosphate esters (Cl-OPEs) have high water solubility and structural similarity to organophosphate pesticides, posing risks to aquatic organisms. The potential neurotoxicity of Cl-OPEs has attracted attention, especially in marine invertebrates with a relatively simple nervous system. In this study, a marine rotifer with a cerebral ganglion, Brachionus plicatilis, was exposed to tris (1,3-dichloro-2-propyl) phosphate (TDCPP) (two environmental concentrations and one extreme level), and the changes in feeding and swimming behaviors and internal mechanism were explored. Exposure to 1.05 nM TDCPP did not change the filtration and ingestion rates of rotifers and average linear velocity. But 0.42 and 4.20 μM TDCPP inhibited these three parameters and reduced unsaturated fatty acid content, reproduction and population growth. All TDCPP test concentrations suppressed AChE activity, causing excessive accumulation of acetylcholine within rotifers, thereby disturbing the neural innervation of corona cilia. Molecular docking and molecular dynamics revealed that this inhibition was because TDCPP can bind to the catalytic active site of rotifer AChE through van der Waals forces and electrostatic interactions. TRP420 was the leading amino residue in the binding, and GLY207 contributed to a hydrogen bond. Nontargeted metabolomics using LC-MS and GC-MS identified differentially expressed metabolites in TDCPP treatments, mainly from lipid and lipid-like molecules, especially sphingolipids. TDCPP decreased ganglioside content but stimulated ceramide generation and the expression levels of 3 genes related to ceramide de novo synthesis. The mitochondrial membrane potential (MMP) and ATP content decreased, and the electron respiratory chain complex and TCA cycle were deactivated. An inhibitor of ceramide synthase, fumonisin, alleviated MMP and ATP, implying a critical role of ceramide in mitochondrial dysfunction. Thus, TDCPP exposure caused an energy supply deficit affecting ciliary movement and ultimately inhibiting rotifer behaviors. Overall, this study promotes the understanding of the neurotoxicity of Cl-OPEs in marine invertebrates.
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Affiliation(s)
- Xin Zhang
- Department of Marine Ecology, College of Marine Life Science, Ocean University of China, Qingdao 266003, China
| | - Xin Tong
- Department of Marine Ecology, College of Marine Life Science, Ocean University of China, Qingdao 266003, China
| | - Xuexi Tang
- Department of Marine Ecology, College of Marine Life Science, Ocean University of China, Qingdao 266003, China; Laboratory for Marine Ecology and Environmental Science, Pilot National Laboratory for Marine Science and Technology, Qingdao 266237, China
| | - Yixin Yang
- Department of Marine Ecology, College of Marine Life Science, Ocean University of China, Qingdao 266003, China
| | - Luyuchen Zhang
- Department of Marine Ecology, College of Marine Life Science, Ocean University of China, Qingdao 266003, China
| | - Xiaotong Zhan
- Department of Marine Ecology, College of Marine Life Science, Ocean University of China, Qingdao 266003, China
| | - Xinxin Zhang
- Department of Marine Ecology, College of Marine Life Science, Ocean University of China, Qingdao 266003, China; Laboratory for Marine Ecology and Environmental Science, Pilot National Laboratory for Marine Science and Technology, Qingdao 266237, China.
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Yang Z, Zhang L, Zhang W, Tian X, Lai W, Lin D, Feng Y, Jiang W, Zhang Z, Zhang Z. Identification of the principal neuropeptide MIP and its action pathway in larval settlement of the echiuran worm Urechis unicinctus. BMC Genomics 2024; 25:337. [PMID: 38641568 PMCID: PMC11027379 DOI: 10.1186/s12864-024-10228-y] [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: 12/30/2023] [Accepted: 03/15/2024] [Indexed: 04/21/2024] Open
Abstract
BACKGROUND Larval settlement and metamorphosis represent critical events in the life history of marine benthic animals. Myoinhibitory peptide (MIP) plays a pivotal role in larval settlement of marine invertebrates. However, the molecular mechanisms of MIP involved in this process are not well understood. RESULTS In this study, we evaluated the effects of thirteen MIP mature peptides on triggering the larval settlement of Urechis unicinctus (Xenopneusta, Urechidae), and determined that MIP2 was the principal neuropeptide. Transcriptomic analysis was employed to identify differentially expressed genes (DEGs) between the MIP2-treated larvae and normal early-segmentation larvae. Both cAMP and calcium signaling pathways were enriched in the DEGs of the MIP2-treated larvae, and two neuropeptide receptor genes (Spr, Fmrfar) were up-regulated in the MIP2-treated larvae. The activation of the SPR-cAMP pathway by MIP2 was experimentally validated in HEK293T cells. Furthermore, fourteen cilia-related genes, including Tctex1d2, Cfap45, Ift43, Ift74, Ift22, Cav1 and Mns1, etc. exhibited down-regulated expression in the MIP2-treated larvae. Whole-mount in situ hybridization identified two selected ciliary genes, Tctex1d2 and Cfap45, were specially expressed in circumoral ciliary cells of the early-segmentation larvae. Knocking down Tctex1d2 mRNA levels by in vivo RNA interference significantly increased the larval settlement rate. CONCLUSION Our findings suggest that MIP2 inhibits the function of the cilia-related genes, such as Tctex1d2, through the SPR-cAMP-PKA pathway, thereby inducing larval settlement in U. unicinctus. The study contributes important data to the understanding of neuropeptide regulation in larval settlement.
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Affiliation(s)
- Zhi Yang
- Key Laboratory of Tropical Aquatic Germplasm of Hainan Province, Sanya Ocean Institute, Ocean University of China, Sanya, China
| | - Long Zhang
- Key Laboratory of Tropical Aquatic Germplasm of Hainan Province, Sanya Ocean Institute, Ocean University of China, Sanya, China
| | - Wenqing Zhang
- Key Laboratory of Tropical Aquatic Germplasm of Hainan Province, Sanya Ocean Institute, Ocean University of China, Sanya, China
| | - Xinhua Tian
- Key Laboratory of Tropical Aquatic Germplasm of Hainan Province, Sanya Ocean Institute, Ocean University of China, Sanya, China
| | - Wenyuan Lai
- Ministry of Education Key Laboratory of Marine Genetics and Breeding, College of Marine Life Sciences, Ocean University of China, Qingdao, China
| | - Dawei Lin
- Key Laboratory of Tropical Aquatic Germplasm of Hainan Province, Sanya Ocean Institute, Ocean University of China, Sanya, China
| | - Yuxin Feng
- Key Laboratory of Tropical Aquatic Germplasm of Hainan Province, Sanya Ocean Institute, Ocean University of China, Sanya, China
| | - Wenwen Jiang
- Key Laboratory of Tropical Aquatic Germplasm of Hainan Province, Sanya Ocean Institute, Ocean University of China, Sanya, China
| | - Zhengrui Zhang
- Ministry of Education Key Laboratory of Marine Genetics and Breeding, College of Marine Life Sciences, Ocean University of China, Qingdao, China.
| | - Zhifeng Zhang
- Key Laboratory of Tropical Aquatic Germplasm of Hainan Province, Sanya Ocean Institute, Ocean University of China, Sanya, China.
- Ministry of Education Key Laboratory of Marine Genetics and Breeding, College of Marine Life Sciences, Ocean University of China, Qingdao, China.
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Carrillo-Baltodano AM, Donnellan RD, Williams EA, Jékely G, Martín-Durán JM. The development of the adult nervous system in the annelid Owenia fusiformis. Neural Dev 2024; 19:3. [PMID: 38383501 PMCID: PMC10880339 DOI: 10.1186/s13064-024-00180-8] [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: 11/14/2023] [Accepted: 02/02/2024] [Indexed: 02/23/2024] Open
Abstract
BACKGROUND The evolutionary origins of animal nervous systems remain contentious because we still have a limited understanding of neural development in most major animal clades. Annelids - a species-rich group with centralised nervous systems - have played central roles in hypotheses about the origins of animal nervous systems. However, most studies have focused on adults of deeply nested species in the annelid tree. Recently, Owenia fusiformis has emerged as an informative species to reconstruct ancestral traits in Annelida, given its phylogenetic position within the sister clade to all remaining annelids. METHODS Combining immunohistochemistry of the conserved neuropeptides FVamide-lir, RYamide-lir, RGWamide-lir and MIP-lir with gene expression, we comprehensively characterise neural development from larva to adulthood in Owenia fusiformis. RESULTS The early larval nervous system comprises a neuropeptide-rich apical organ connected through peripheral nerves to a prototroch ring and the chaetal sac. There are seven sensory neurons in the prototroch. A bilobed brain forms below the apical organ and connects to the ventral nerve cord of the developing juvenile. During metamorphosis, the brain compresses, becoming ring-shaped, and the trunk nervous system develops several longitudinal cords and segmented lateral nerves. CONCLUSIONS Our findings reveal the formation and reorganisation of the nervous system during the life cycle of O. fusiformis, an early-branching annelid. Despite its apparent neuroanatomical simplicity, this species has a diverse peptidergic nervous system, exhibiting morphological similarities with other annelids, particularly at the larval stages. Our work supports the importance of neuropeptides in animal nervous systems and highlights how neuropeptides are differentially used throughout development.
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Affiliation(s)
| | - Rory D Donnellan
- School of Biological and Behavioural Sciences, Queen Mary University of London, London, UK
| | | | - Gáspár Jékely
- Living Systems Institute, University of Exeter, Exeter, UK
- Centre for Organismal Studies (COS), University of Heidelberg, Heidelberg, Germany
| | - José M Martín-Durán
- School of Biological and Behavioural Sciences, Queen Mary University of London, London, UK
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Wan KY, Poon RN. Mechanisms and functions of multiciliary coordination. Curr Opin Cell Biol 2024; 86:102286. [PMID: 38035649 DOI: 10.1016/j.ceb.2023.102286] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2023] [Revised: 10/20/2023] [Accepted: 11/02/2023] [Indexed: 12/02/2023]
Abstract
Ciliated organisms are present in virtually every branch of the eukaryotic tree of life. In diverse systems, cilia operate in a coordinated manner to drive fluid flows, or even propel entire organisms. How do groups of motile cilia coordinate their activity within a cell or across a tissue to fulfil essential functions of life? In this review, we highlight the latest developments in our understanding of the mechanisms and functions of multiciliary coordination in diverse systems. We explore new and emerging trends in bioimaging, analytical, and computational methods, which together with their application in new model systems, have conspired to deliver important insights into one of the most fundamental questions in cellular dynamics.
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Affiliation(s)
- Kirsty Y Wan
- Living Systems Institute, University of Exeter, Stocker Road, EX4 4QD, UK.
| | - Rebecca N Poon
- Living Systems Institute, University of Exeter, Stocker Road, EX4 4QD, UK
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Gilbert E, Craggs J, Modepalli V. Gene Regulatory Network that Shaped the Evolution of Larval Apical Organ in Cnidaria. Mol Biol Evol 2024; 41:msad285. [PMID: 38152864 PMCID: PMC10781443 DOI: 10.1093/molbev/msad285] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2023] [Revised: 11/24/2023] [Accepted: 12/21/2023] [Indexed: 12/29/2023] Open
Abstract
Among non-bilaterian animals, a larval apical sensory organ with integrated neurons is only found in cnidarians. Within cnidarians, an apical organ with a ciliary tuft is mainly found in Actiniaria. Whether this apical tuft has evolved independently in Actiniaria or alternatively originated in the common ancestor of Cnidaria and Bilateria and was lost in specific groups is uncertain. To test this hypothesis, we generated transcriptomes of the apical domain during the planula stage of four species representing three key groups of cnidarians: Aurelia aurita (Scyphozoa), Nematostella vectensis (Actiniaria), and Acropora millepora and Acropora tenuis (Scleractinia). We showed that the canonical genes implicated in patterning the apical domain of N. vectensis are largely absent in A. aurita. In contrast, the apical domain of the scleractinian planula shares gene expression pattern with N. vectensis. By comparing the larval single-cell transcriptomes, we revealed the apical organ cell type of Scleractinia and confirmed its homology to Actiniaria. However, Fgfa2, a vital regulator of the regionalization of the N. vectensis apical organ, is absent in the scleractinian genome. Likewise, we found that FoxJ1 and 245 genes associated with cilia are exclusively expressed in the N. vectensis apical domain, which is in line with the presence of ciliary apical tuft in Actiniaria and its absence in Scleractinia and Scyphozoa. Our findings suggest that the common ancestor of cnidarians lacked a ciliary apical tuft, and it could have evolved independently in the Actiniaria.
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Affiliation(s)
- Eleanor Gilbert
- Marine Biological Association of the UK, The Laboratory, Citadel Hill, Plymouth PL1 2PB, UK
- School of Biological and Marine Sciences, University of Plymouth, Plymouth PL4 8AA, UK
| | - Jamie Craggs
- Horniman Museum and Gardens, London SE23 3PQ, UK
| | - Vengamanaidu Modepalli
- Marine Biological Association of the UK, The Laboratory, Citadel Hill, Plymouth PL1 2PB, UK
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7
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Larson BT. Perspectives on Principles of Cellular Behavior from the Biophysics of Protists. Integr Comp Biol 2023; 63:1405-1421. [PMID: 37496203 PMCID: PMC10755178 DOI: 10.1093/icb/icad106] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2023] [Revised: 07/14/2023] [Accepted: 07/17/2023] [Indexed: 07/28/2023] Open
Abstract
Cells are the fundamental unit of biological organization. Although it may be easy to think of them as little more than the simple building blocks of complex organisms such as animals, single cells are capable of behaviors of remarkable apparent sophistication. This is abundantly clear when considering the diversity of form and function among the microbial eukaryotes, the protists. How might we navigate this diversity in the search for general principles of cellular behavior? Here, we review cases in which the intensive study of protists from the perspective of cellular biophysics has driven insight into broad biological questions of morphogenesis, navigation and motility, and decision making. We argue that applying such approaches to questions of evolutionary cell biology presents rich, emerging opportunities. Integrating and expanding biophysical studies across protist diversity, exploiting the unique characteristics of each organism, will enrich our understanding of general underlying principles.
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Affiliation(s)
- Ben T Larson
- Department of Biochemistry and Biophysics, University of California, San Francisco, CA 94158, USA
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Bastin BR, Meha SM, Khindurangala L, Schneider SQ. Cooption of regulatory modules for tektin paralogs during ciliary band formation in a marine annelid larva. Dev Biol 2023; 503:95-110. [PMID: 37557946 DOI: 10.1016/j.ydbio.2023.07.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2023] [Revised: 07/25/2023] [Accepted: 07/28/2023] [Indexed: 08/11/2023]
Abstract
Tektins are a highly conserved family of coiled-coil domain containing proteins known to play a role in structure, stability and function of cilia and flagella. Tektin proteins are thought to form filaments which run the length of the axoneme along the inner surface of the A tubule of each microtubule doublet. Phylogenetic analyses suggest that the tektin family arose via duplications from a single tektin gene in a unicellular organism giving rise to four and five tektin genes in bilaterians and in spiralians, respectively. Although tektins are found in most metazoans, little is known about their expression and function outside of a handful of model species. Here we present the first comprehensive study of tektin family gene expression in any animal system, in the spiralian annelid Platynereis dumerilii. This indirect developing species retains a full ancient spiralian complement of five tektin genes. We show that all five tektins are expressed almost exclusively in known ciliary structures following the expression of the motile cilia master regulator foxJ1. The three older bilaterian tektin-1, tektin-2, and tektin-4 genes, show a high degree of spatial and temporal co-regulation, while the spiralian specific tektin-3/5A and tektin-3/5B show a delay in onset of expression in every ciliary structure. In addition, tektin-3/5B transcripts show a restricted subcellular localization to the most apical region near the multiciliary arrays. The exact recapitulation of the sequence of expression and localization of the five tektins at different times during larval development indicates the cooption of a fixed regulatory and cellular program during the formation of each ciliary band and multiciliated cell type in this spiralian.
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Affiliation(s)
- Benjamin R Bastin
- Department of Genetics, Development and Cell Biology, Iowa State University, Ames, IA, USA.
| | - Steffanie M Meha
- Institute of Cellular and Organismic Biology, Academia Sinica, Taipei, Taiwan.
| | - Lalith Khindurangala
- Department of Genetics, Development and Cell Biology, Iowa State University, Ames, IA, USA.
| | - Stephan Q Schneider
- Department of Genetics, Development and Cell Biology, Iowa State University, Ames, IA, USA; Institute of Cellular and Organismic Biology, Academia Sinica, Taipei, Taiwan.
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9
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Zhang X, Tang X, Yang Y, Tong X, Hu H, Zhang X. Tributyl phosphate can inhibit the feeding behavior of rotifers by altering the axoneme structure, neuronal coordination and energy supply required for motile cilia. JOURNAL OF HAZARDOUS MATERIALS 2023; 459:132224. [PMID: 37557041 DOI: 10.1016/j.jhazmat.2023.132224] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/10/2023] [Revised: 07/24/2023] [Accepted: 08/02/2023] [Indexed: 08/11/2023]
Abstract
Organophosphorus flame retardants (OPFRs) are frequently detected in aquatic environments and can potentially amplify the food chain, posing a potential risk to organisms. Marine invertebrates have primitive nervous systems to regulate behavior, but how they respond to OPFRs that are potentially neurotoxic substances is unclear. This study assessed changes in the feeding behavior of rotifer Brachionus plicatilis exposed to alkyl OPFRs tributyl phosphate (TnBP) (0.376 nM, 3.76 and 22.53 µM) to elucidate the mechanism of behavioral toxicity. TnBP at 22.53 μM reduced the ingestion and filtration rates of rotifers for Chlorella vulgaris and Phaeocystis globosa in a 24-h test and altered rotifer-P. globosa population dynamics in 15-d coculture. Ciliary beat frequency was also reduced, and the expression of genes encoding the cilia axoneme was downregulated. TnBP could inhibit rotifer acetylcholinesterase activity by binding this protein and reduce the expression of the exocytotic membrane protein syntaxin-4, suggesting a disorder in nervous regulation of cilia beat. Moreover, TnBP induced abnormal shape and dysfunction of mitochondria, which caused insufficient energy required for ciliary movement. This study revealed diverse neurotoxicity mechanisms of TnBP, particularly as a potentially competing acetylcholinesterase ligand for aquatic invertebrates. Our research also provides a meaningful reference for OPFR-induced behavioral toxicity assessments.
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Affiliation(s)
- Xin Zhang
- Department of Marine Ecology, College of Marine Life Science, Ocean University of China, Qingdao 266003, China
| | - Xuexi Tang
- Department of Marine Ecology, College of Marine Life Science, Ocean University of China, Qingdao 266003, China
| | - Yingying Yang
- Department of Marine Ecology, College of Marine Life Science, Ocean University of China, Qingdao 266003, China
| | - Xin Tong
- Department of Marine Ecology, College of Marine Life Science, Ocean University of China, Qingdao 266003, China
| | - Hanwen Hu
- Department of Marine Ecology, College of Marine Life Science, Ocean University of China, Qingdao 266003, China
| | - Xinxin Zhang
- Department of Marine Ecology, College of Marine Life Science, Ocean University of China, Qingdao 266003, China.
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10
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Piovani L, Leite DJ, Yañez Guerra LA, Simpson F, Musser JM, Salvador-Martínez I, Marlétaz F, Jékely G, Telford MJ. Single-cell atlases of two lophotrochozoan larvae highlight their complex evolutionary histories. SCIENCE ADVANCES 2023; 9:eadg6034. [PMID: 37531419 PMCID: PMC10396302 DOI: 10.1126/sciadv.adg6034] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/14/2023] [Accepted: 06/30/2023] [Indexed: 08/04/2023]
Abstract
Pelagic larval stages are widespread across animals, yet it is unclear whether larvae were present in the last common ancestor of animals or whether they evolved multiple times due to common selective pressures. Many marine larvae are at least superficially similar; they are small, swim through the beating of bands of cilia, and sense the environment with an apical organ. To understand these similarities, we have generated single-cell atlases for marine larvae from two animal phyla and have compared their cell types. We found clear similarities among ciliary band cells and between neurons of the apical organ in the two larvae pointing to possible homology of these structures, suggesting a single origin of larvae within Spiralia. We also find several clade-specific innovations in each larva, including distinct myocytes and shell gland cells in the oyster larva. Oyster shell gland cells express many recently evolved genes that have made previous gene age estimates for the origin of trochophore larvae too young.
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Affiliation(s)
- Laura Piovani
- Centre for Life’s Origins and Evolution, Department of Genetics, Evolution and Environment, University College London, London WC1E 6BT, UK
| | - Daniel J. Leite
- Centre for Life’s Origins and Evolution, Department of Genetics, Evolution and Environment, University College London, London WC1E 6BT, UK
| | | | - Fraser Simpson
- Centre for Life’s Origins and Evolution, Department of Genetics, Evolution and Environment, University College London, London WC1E 6BT, UK
| | - Jacob M. Musser
- Developmental Biology Unit, European Molecular Biology Laboratory, 69117 Heidelberg, Germany
| | - Irepan Salvador-Martínez
- Centre for Life’s Origins and Evolution, Department of Genetics, Evolution and Environment, University College London, London WC1E 6BT, UK
| | - Ferdinand Marlétaz
- Centre for Life’s Origins and Evolution, Department of Genetics, Evolution and Environment, University College London, London WC1E 6BT, UK
| | - Gáspár Jékely
- Living Systems Institute, University of Exeter, Stocker Road, Exeter, UK
| | - Maximilian J. Telford
- Centre for Life’s Origins and Evolution, Department of Genetics, Evolution and Environment, University College London, London WC1E 6BT, UK
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11
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Pavarino EC, Yang E, Dhanyasi N, Wang MD, Bidel F, Lu X, Yang F, Francisco Park C, Bangalore Renuka M, Drescher B, Samuel ADT, Hochner B, Katz PS, Zhen M, Lichtman JW, Meirovitch Y. mEMbrain: an interactive deep learning MATLAB tool for connectomic segmentation on commodity desktops. Front Neural Circuits 2023; 17:952921. [PMID: 37396399 PMCID: PMC10309043 DOI: 10.3389/fncir.2023.952921] [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: 05/25/2022] [Accepted: 04/17/2023] [Indexed: 07/04/2023] Open
Abstract
Connectomics is fundamental in propelling our understanding of the nervous system's organization, unearthing cells and wiring diagrams reconstructed from volume electron microscopy (EM) datasets. Such reconstructions, on the one hand, have benefited from ever more precise automatic segmentation methods, which leverage sophisticated deep learning architectures and advanced machine learning algorithms. On the other hand, the field of neuroscience at large, and of image processing in particular, has manifested a need for user-friendly and open source tools which enable the community to carry out advanced analyses. In line with this second vein, here we propose mEMbrain, an interactive MATLAB-based software which wraps algorithms and functions that enable labeling and segmentation of electron microscopy datasets in a user-friendly user interface compatible with Linux and Windows. Through its integration as an API to the volume annotation and segmentation tool VAST, mEMbrain encompasses functions for ground truth generation, image preprocessing, training of deep neural networks, and on-the-fly predictions for proofreading and evaluation. The final goals of our tool are to expedite manual labeling efforts and to harness MATLAB users with an array of semi-automatic approaches for instance segmentation. We tested our tool on a variety of datasets that span different species at various scales, regions of the nervous system and developmental stages. To further expedite research in connectomics, we provide an EM resource of ground truth annotation from four different animals and five datasets, amounting to around 180 h of expert annotations, yielding more than 1.2 GB of annotated EM images. In addition, we provide a set of four pre-trained networks for said datasets. All tools are available from https://lichtman.rc.fas.harvard.edu/mEMbrain/. With our software, our hope is to provide a solution for lab-based neural reconstructions which does not require coding by the user, thus paving the way to affordable connectomics.
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Affiliation(s)
- Elisa C. Pavarino
- Department of Cellular and Molecular Biology, Harvard University, Cambridge, MA, United States
| | - Emma Yang
- Department of Cellular and Molecular Biology, Harvard University, Cambridge, MA, United States
| | - Nagaraju Dhanyasi
- Department of Cellular and Molecular Biology, Harvard University, Cambridge, MA, United States
| | - Mona D. Wang
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, ON, Canada
- Department of Molecular Genetics, University of Toronto, Toronto, ON, Canada
| | - Flavie Bidel
- Department of Neurobiology, Silberman Institute of Life Sciences, The Hebrew University, Jerusalem, Israel
| | - Xiaotang Lu
- Department of Cellular and Molecular Biology, Harvard University, Cambridge, MA, United States
| | - Fuming Yang
- Department of Cellular and Molecular Biology, Harvard University, Cambridge, MA, United States
| | | | - Mukesh Bangalore Renuka
- Department of Cellular and Molecular Biology, Harvard University, Cambridge, MA, United States
| | - Brandon Drescher
- Department of Biology, University of Massachusetts Amherst, Amherst, MA, United States
| | | | - Binyamin Hochner
- Department of Neurobiology, Silberman Institute of Life Sciences, The Hebrew University, Jerusalem, Israel
| | - Paul S. Katz
- Department of Biology, University of Massachusetts Amherst, Amherst, MA, United States
| | - Mei Zhen
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, ON, Canada
| | - Jeff W. Lichtman
- Department of Cellular and Molecular Biology, Harvard University, Cambridge, MA, United States
| | - Yaron Meirovitch
- Department of Cellular and Molecular Biology, Harvard University, Cambridge, MA, United States
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Pavarino EC, Yang E, Dhanyasi N, Wang M, Bidel F, Lu X, Yang F, Park CF, Renuka MB, Drescher B, Samuel AD, Hochner B, Katz PS, Zhen M, Lichtman JW, Meirovitch Y. mEMbrain: an interactive deep learning MATLAB tool for connectomic segmentation on commodity desktops. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.04.17.537196. [PMID: 37131600 PMCID: PMC10153173 DOI: 10.1101/2023.04.17.537196] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Connectomics is fundamental in propelling our understanding of the nervous system’s organization, unearthing cells and wiring diagrams reconstructed from volume electron microscopy (EM) datasets. Such reconstructions, on the one hand, have benefited from ever more precise automatic segmentation methods, which leverage sophisticated deep learning architectures and advanced machine learning algorithms. On the other hand, the field of neuroscience at large, and of image processing in particular, has manifested a need for user-friendly and open source tools which enable the community to carry out advanced analyses. In line with this second vein, here we propose mEMbrain, an interactive MATLAB-based software which wraps algorithms and functions that enable labeling and segmentation of electron microscopy datasets in a user-friendly user interface compatible with Linux and Windows. Through its integration as an API to the volume annotation and segmentation tool VAST, mEMbrain encompasses functions for ground truth generation, image preprocessing, training of deep neural networks, and on-the-fly predictions for proofreading and evaluation. The final goals of our tool are to expedite manual labeling efforts and to harness MATLAB users with an array of semi-automatic approaches for instance segmentation. We tested our tool on a variety of datasets that span different species at various scales, regions of the nervous system and developmental stages. To further expedite research in connectomics, we provide an EM resource of ground truth annotation from 4 different animals and 5 datasets, amounting to around 180 hours of expert annotations, yielding more than 1.2 GB of annotated EM images. In addition, we provide a set of 4 pre-trained networks for said datasets. All tools are available from https://lichtman.rc.fas.harvard.edu/mEMbrain/ . With our software, our hope is to provide a solution for lab-based neural reconstructions which does not require coding by the user, thus paving the way to affordable connectomics.
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Affiliation(s)
| | - Emma Yang
- Department of Cellular and Molecular Biology, Harvard University, Cambridge, MA, USA
| | - Nagaraju Dhanyasi
- Department of Cellular and Molecular Biology, Harvard University, Cambridge, MA, USA
| | - Mona Wang
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, Ontario, Canada
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada
| | - Flavie Bidel
- Department of Neurobiology, Silberman Institute of Life Sciences, The Hebrew University, Jerusalem, Israel
| | - Xiaotang Lu
- Department of Cellular and Molecular Biology, Harvard University, Cambridge, MA, USA
| | - Fuming Yang
- Department of Cellular and Molecular Biology, Harvard University, Cambridge, MA, USA
| | | | | | - Brandon Drescher
- Department Biology, University of Massachusetts Amherst, Amherst, MA, USA
| | | | - Binyamin Hochner
- Department of Neurobiology, Silberman Institute of Life Sciences, The Hebrew University, Jerusalem, Israel
| | - Paul S. Katz
- Department Biology, University of Massachusetts Amherst, Amherst, MA, USA
| | - Mei Zhen
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, Ontario, Canada
| | - Jeff W. Lichtman
- Department of Cellular and Molecular Biology, Harvard University, Cambridge, MA, USA
| | - Yaron Meirovitch
- Department of Cellular and Molecular Biology, Harvard University, Cambridge, MA, USA
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13
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Gilbert E, Teeling C, Lebedeva T, Pedersen S, Chrismas N, Genikhovich G, Modepalli V. Molecular and cellular architecture of the larval sensory organ in the cnidarian Nematostella vectensis. Development 2022; 149:276422. [PMID: 36000354 PMCID: PMC9481973 DOI: 10.1242/dev.200833] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2022] [Accepted: 07/18/2022] [Indexed: 11/29/2022]
Abstract
Cnidarians are the only non-bilaterian group to evolve ciliated larvae with an apical sensory organ, which is possibly homologous to the apical organs of bilaterian primary larvae. Here, we generated transcriptomes of the apical tissue in the sea anemone Nematostella vectensis and showed that it has a unique neuronal signature. By integrating previously published larval single-cell data with our apical transcriptomes, we discovered that the apical domain comprises a minimum of six distinct cell types. We show that the apical organ is compartmentalised into apical tuft cells (spot) and larval-specific neurons (ring). Finally, we identify ISX-like (NVE14554), a PRD class homeobox gene specifically expressed in apical tuft cells, as an FGF signalling-dependent transcription factor responsible for the formation of the apical tuft domain via repression of the neural ring fate in apical cells. With this study, we contribute a comparison of the molecular anatomy of apical organs, which must be carried out across phyla to determine whether this crucial larval structure evolved once or multiple times. Summary:ISX-like homeobox gene is an FGF signalling-dependent transcription factor responsible for the formation of the apical tuft in the sea anemone Nematostella vectensis.
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Affiliation(s)
- Eleanor Gilbert
- Marine Biological Association of the UK, The Laboratory 1 , Citadel Hill, Plymouth PL1 2PB , United Kingdom
- School of Biological and Marine Sciences, University of Plymouth 2 , Plymouth, PL4 8AA , UK
| | - Callum Teeling
- Marine Biological Association of the UK, The Laboratory 1 , Citadel Hill, Plymouth PL1 2PB , United Kingdom
- School of Biological and Marine Sciences, University of Plymouth 2 , Plymouth, PL4 8AA , UK
| | - Tatiana Lebedeva
- University of Vienna 3 Department of Neurosciences and Developmental Biology, Faculty of Life Sciences , , Vienna, 1030 , Austria
- Doctoral School of Ecology and Evolution, University of Vienna 4 , Vienna, 1030 , Austria
| | - Siffreya Pedersen
- Marine Biological Association of the UK, The Laboratory 1 , Citadel Hill, Plymouth PL1 2PB , United Kingdom
| | - Nathan Chrismas
- Marine Biological Association of the UK, The Laboratory 1 , Citadel Hill, Plymouth PL1 2PB , United Kingdom
| | - Grigory Genikhovich
- University of Vienna 3 Department of Neurosciences and Developmental Biology, Faculty of Life Sciences , , Vienna, 1030 , Austria
| | - Vengamanaidu Modepalli
- Marine Biological Association of the UK, The Laboratory 1 , Citadel Hill, Plymouth PL1 2PB , United Kingdom
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14
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Nedved BT, Freckelton ML, Hadfield MG. Laser ablation of the apical sensory organ of Hydroides elegans (Polychaeta) does not inhibit detection of metamorphic cues. J Exp Biol 2021; 224:272553. [PMID: 34553756 DOI: 10.1242/jeb.242300] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2021] [Accepted: 09/14/2021] [Indexed: 11/20/2022]
Abstract
Larvae of many marine invertebrates bear an anteriorly positioned apical sensory organ (ASO) presumed to be the receptor for settlement- and metamorphosis-inducing environmental cues, based on its structure, position and observed larval behavior. Larvae of the polychaete Hydroides elegans are induced to settle by bacterial biofilms, which they explore with their ASO and surrounding anteroventral surfaces. A micro-laser was utilized to destroy the ASO and other anterior ciliary structures in competent larvae of H. elegans. After ablation, larvae were challenged with bacterial biofilmed or clean surfaces and percentage metamorphosis was determined. Ablated larvae were also assessed for cellular damage by applying fluorescently tagged FMRF-amide antibodies and observing the larvae by laser-scanning confocal microscopy. While the laser pulses caused extensive damage to the ASO and surrounding cells, they did not inhibit metamorphosis. We conclude that the ASO is not a required receptor site for cues that induce metamorphosis.
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Affiliation(s)
- Brian T Nedved
- University of Hawaii, Kewalo Marine Laboratory, Honolulu, HI 96813, USA
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15
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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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16
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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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17
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Hamilton E, Cicuta P. Changes in geometrical aspects of a simple model of cilia synchronization control the dynamical state, a possible mechanism for switching of swimming gaits in microswimmers. PLoS One 2021; 16:e0249060. [PMID: 33831025 PMCID: PMC8031381 DOI: 10.1371/journal.pone.0249060] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2020] [Accepted: 03/10/2021] [Indexed: 12/23/2022] Open
Abstract
Active oscillators, with purely hydrodynamic coupling, are useful simple models to understand various aspects of motile cilia synchronization. Motile cilia are used by microorganisms to swim and to control the flow fields in their surroundings; the patterns observed in cilia carpets can be remarkably complex, and can be changed over time by the organism. It is often not known to what extent the coupling between cilia is due to just hydrodynamic forces, and neither is it known if it is biological or physical triggers that can change the dynamical collective state. Here we treat this question from a very simplified point of view. We describe three possible mechanisms that enable a switch in the dynamical state, in a simple scenario of a chain of oscillators. We find that shape-change provides the most consistent strategy to control collective dynamics, but also imposing small changes in frequency produces some unique stable states. Demonstrating these effects in the abstract minimal model proves that these could be possible explanations for gait switching seen in ciliated micro organisms like Paramecium and others. Microorganisms with many cilia could in principle be taking advantage of hydrodynamic coupling, to switch their swimming gait through either a shape change that manifests in decreased coupling between groups of cilia, or alterations to the beat style of a small subset of the cilia.
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Affiliation(s)
- Evelyn Hamilton
- Cavendish Laboratory, University of Cambridge, Cambridge, United Kingdom
| | - Pietro Cicuta
- Cavendish Laboratory, University of Cambridge, Cambridge, United Kingdom
- * E-mail:
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18
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Kuo DH, De-Miguel FF, Heath-Heckman EAC, Szczupak L, Todd K, Weisblat DA, Winchell CJ. A tale of two leeches: Toward the understanding of the evolution and development of behavioral neural circuits. Evol Dev 2020; 22:471-493. [PMID: 33226195 DOI: 10.1111/ede.12358] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2019] [Revised: 10/23/2020] [Accepted: 11/02/2020] [Indexed: 11/29/2022]
Abstract
In the animal kingdom, behavioral traits encompass a broad spectrum of biological phenotypes that have critical roles in adaptive evolution, but an EvoDevo approach has not been broadly used to study behavior evolution. Here, we propose that, by integrating two leech model systems, each of which has already attained some success in its respective field, it is possible to take on behavioral traits with an EvoDevo approach. We first identify the developmental changes that may theoretically lead to behavioral evolution and explain why an EvoDevo study of behavior is challenging. Next, we discuss the pros and cons of the two leech model species, Hirudo, a classic model for invertebrate neurobiology, and Helobdella, an emerging model for clitellate developmental biology, as models for behavioral EvoDevo research. Given the limitations of each leech system, neither is particularly strong for behavioral EvoDevo. However, the two leech systems are complementary in their technical accessibilities, and they do exhibit some behavioral similarities and differences. By studying them in parallel and together with additional leech species such as Haementeria, it is possible to explore the different levels of behavioral development and evolution.
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Affiliation(s)
- Dian-Han Kuo
- Department of Life Science, National Taiwan University, Taipei, Taiwan
| | - Francisco F De-Miguel
- Instituto de Fisiología Celular - Neurociencias, Universidad Nacional Autónoma de México, México City, México
| | | | - Lidia Szczupak
- Departamento de Fisiología Biología Molecular y Celular, Universidad de Buenos Aires, and IFIBYNE UBA-CONICET, Buenos Aires, Argentina
| | - Krista Todd
- Department of Neuroscience, Westminster College, Salt Lake City, Utah, USA
| | - David A Weisblat
- Department of Molecular and Cell Biology, University of California, Berkeley, California, USA
| | - Christopher J Winchell
- Department of Molecular and Cell Biology, University of California, Berkeley, California, USA
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19
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Cook SJ, Crouse CM, Yemini E, Hall DH, Emmons SW, Hobert O. The connectome of the Caenorhabditis elegans pharynx. J Comp Neurol 2020; 528:2767-2784. [PMID: 32352566 PMCID: PMC7601127 DOI: 10.1002/cne.24932] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2019] [Revised: 04/06/2020] [Accepted: 04/17/2020] [Indexed: 12/31/2022]
Abstract
Detailed anatomical maps of individual organs and entire animals have served as invaluable entry points for ensuing dissection of their evolution, development, and function. The pharynx of the nematode Caenorhabditis elegans is a simple neuromuscular organ with a self-contained, autonomously acting nervous system, composed of 20 neurons that fall into 14 anatomically distinct types. Using serial electron micrograph (EM) reconstruction, we re-evaluate here the connectome of the pharyngeal nervous system, providing a novel and more detailed view of its structure and predicted function. Contrasting the previous classification of pharyngeal neurons into distinct inter- and motor neuron classes, we provide evidence that most pharyngeal neurons are also likely sensory neurons and most, if not all, pharyngeal neurons also classify as motor neurons. Together with the extensive cross-connectivity among pharyngeal neurons, which is more widespread than previously realized, the sensory-motor characteristics of most neurons define a shallow network architecture of the pharyngeal connectome. Network analysis reveals that the patterns of neuronal connections are organized into putative computational modules that reflect the known functional domains of the pharynx. Compared with the somatic nervous system, pharyngeal neurons both physically associate with a larger fraction of their neighbors and create synapses with a greater proportion of their neighbors. We speculate that the overall architecture of the pharyngeal nervous system may be reminiscent of the architecture of ancestral, primitive nervous systems.
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Affiliation(s)
- Steven J. Cook
- Department of Biological Sciences, Columbia University, Howard Hughes Medical Institute, New York, NY 10027
| | - Charles M. Crouse
- Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, Bronx, NY 10461
| | - Eviatar Yemini
- Department of Biological Sciences, Columbia University, Howard Hughes Medical Institute, New York, NY 10027
| | - David H. Hall
- Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, Bronx, NY 10461
| | - Scott W. Emmons
- Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, Bronx, NY 10461
- Department of Genetics, Albert Einstein College of Medicine, Bronx, NY 10461
| | - Oliver Hobert
- Department of Biological Sciences, Columbia University, Howard Hughes Medical Institute, New York, NY 10027
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20
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Bischof J, Day ME, Miller KA, LaPalme JV, Levin M. Nervous system and tissue polarity dynamically adapt to new morphologies in planaria. Dev Biol 2020; 467:51-65. [PMID: 32882234 PMCID: PMC10474925 DOI: 10.1016/j.ydbio.2020.08.009] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2020] [Revised: 08/03/2020] [Accepted: 08/14/2020] [Indexed: 02/05/2023]
Abstract
The coordination of tissue-level polarity with organism-level polarity is crucial in development, disease, and regeneration. Here, we characterize a new example of large-scale control of dynamic remodeling of body polarity. Exploiting the flexibility of the body plan in regenerating planarians, we used mirror duplication of the primary axis to show how established tissue-level polarity adapts to new organism-level polarity. Characterization of epithelial planar cell polarity revealed a remarkable reorientation of tissue polarity in double-headed planarians. This reorientation of cilia occurs even following irradiation-induced loss of all stem cells, suggesting independence of the polarity change from the formation of new cells. The presence of the two heads plays an important role in regulating the rate of change in overall polarity. We further present data that suggest that the nervous system itself adapts its polarity to match the new organismal anatomy as revealed by changes in nerve transport driving distinct regenerative outcomes. Thus, in planaria tissue-level polarity can dynamically reorient to match the organism-level anatomical configuration.
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Affiliation(s)
- Johanna Bischof
- Allen Discovery Center at Tufts University, 200 Boston Ave., Suite 4600, Medford, MA, 01915, USA
| | - Margot E Day
- Allen Discovery Center at Tufts University, 200 Boston Ave., Suite 4600, Medford, MA, 01915, USA
| | - Kelsie A Miller
- Allen Discovery Center at Tufts University, 200 Boston Ave., Suite 4600, Medford, MA, 01915, USA
| | - Jennifer V LaPalme
- Allen Discovery Center at Tufts University, 200 Boston Ave., Suite 4600, Medford, MA, 01915, USA
| | - Michael Levin
- Allen Discovery Center at Tufts University, 200 Boston Ave., Suite 4600, Medford, MA, 01915, USA.
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21
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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: 12] [Impact Index Per Article: 3.0] [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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22
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Jokura K, Nishino JM, Ogasawara M, Nishino A. An α7-related nicotinic acetylcholine receptor mediates the ciliary arrest response in pharyngeal gill slits of Ciona. J Exp Biol 2020; 223:jeb209320. [PMID: 32220975 DOI: 10.1242/jeb.209320] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2019] [Accepted: 03/18/2020] [Indexed: 11/20/2022]
Abstract
Ciliary movement is a fundamental process to support animal life, and the movement pattern may be altered in response to external stimuli under the control of nervous systems. Juvenile and adult ascidians have ciliary arrays around their pharyngeal gill slits (stigmata), and continuous beating is interrupted for seconds by mechanical stimuli on other parts of the body. Although it has been suggested that neural transmission to evoke ciliary arrest is cholinergic, its molecular basis has not yet been elucidated in detail. Here, we attempted to clarify the molecular mechanisms underlying this neurociliary transmission in the model ascidian Ciona Acetylcholinesterase histochemical staining showed strong signals on the laterodistal ciliated cells of stigmata, hereafter referred to as trapezial cells. The direct administration of acetylcholine (ACh) and other agonists of nicotinic ACh receptors (nAChRs) onto ciliated cells reliably evoked ciliary arrest that persisted for seconds in a dose-dependent manner. While the Ciona genome encodes ten nAChRs, only one of these called nAChR-A7/8-1, a relative of vertebrate α7 nAChRs, was found to be expressed by trapezial cells. Exogenously expressed nAChR-A7/8-1 on Xenopus oocytes responded to ACh and other agonists with consistent pharmacological traits to those observed in vivo Further efforts to examine signaling downstream of this receptor revealed that an inhibitor of phospholipase C (PLC) hampered ACh-induced ciliary arrest. We propose that homomeric α7-related nAChR-A7/8-1 mediates neurociliary transmission in Ciona stigmata to elicit persistent ciliary arrest by recruiting intracellular Ca2+ signaling.
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Affiliation(s)
- Kei Jokura
- Department of Biology, Faculty of Agriculture and Life Science, Hirosaki University, Hirosaki 036-8561, Japan
- Division of Marine Molecular Biology, Shimoda Marine Research Center, University of Tsukuba, Shimoda 415-0025, Japan
| | - Junko M Nishino
- Department of Bioresources Science, United Graduate School of Agricultural Sciences, Iwate University, Hirosaki 036-8561, Japan
| | - Michio Ogasawara
- Department of Biology, Graduate School of Science, Chiba University, Chiba 263-8522, Japan
| | - Atsuo Nishino
- Department of Biology, Faculty of Agriculture and Life Science, Hirosaki University, Hirosaki 036-8561, Japan
- Department of Bioresources Science, United Graduate School of Agricultural Sciences, Iwate University, Hirosaki 036-8561, Japan
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23
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Bacqué-Cazenave J, Bharatiya R, Barrière G, Delbecque JP, Bouguiyoud N, Di Giovanni G, Cattaert D, De Deurwaerdère P. Serotonin in Animal Cognition and Behavior. Int J Mol Sci 2020; 21:ijms21051649. [PMID: 32121267 PMCID: PMC7084567 DOI: 10.3390/ijms21051649] [Citation(s) in RCA: 143] [Impact Index Per Article: 35.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2020] [Revised: 02/25/2020] [Accepted: 02/25/2020] [Indexed: 12/20/2022] Open
Abstract
Serotonin (5-hydroxytryptamine, 5-HT) is acknowledged as a major neuromodulator of nervous systems in both invertebrates and vertebrates. It has been proposed for several decades that it impacts animal cognition and behavior. In spite of a completely distinct organization of the 5-HT systems across the animal kingdom, several lines of evidence suggest that the influences of 5-HT on behavior and cognition are evolutionary conserved. In this review, we have selected some behaviors classically evoked when addressing the roles of 5-HT on nervous system functions. In particular, we focus on the motor activity, arousal, sleep and circadian rhythm, feeding, social interactions and aggressiveness, anxiety, mood, learning and memory, or impulsive/compulsive dimension and behavioral flexibility. The roles of 5-HT, illustrated in both invertebrates and vertebrates, show that it is more able to potentiate or mitigate the neuronal responses necessary for the fine-tuning of most behaviors, rather than to trigger or halt a specific behavior. 5-HT is, therefore, the prototypical neuromodulator fundamentally involved in the adaptation of all organisms across the animal kingdom.
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Affiliation(s)
- Julien Bacqué-Cazenave
- INCIA, UMR5287, Centre National de la Recherche Scientifique, 33076 Bordeaux, France; (J.B.-C.); (R.B.); (G.B.); (J.-P.D.); (N.B.)
| | - Rahul Bharatiya
- INCIA, UMR5287, Centre National de la Recherche Scientifique, 33076 Bordeaux, France; (J.B.-C.); (R.B.); (G.B.); (J.-P.D.); (N.B.)
- Department of Biomedical Sciences, Section of Neuroscience and Clinical Pharmacology, University of Cagliari, 09100 Cagliari, Italy
| | - Grégory Barrière
- INCIA, UMR5287, Centre National de la Recherche Scientifique, 33076 Bordeaux, France; (J.B.-C.); (R.B.); (G.B.); (J.-P.D.); (N.B.)
| | - Jean-Paul Delbecque
- INCIA, UMR5287, Centre National de la Recherche Scientifique, 33076 Bordeaux, France; (J.B.-C.); (R.B.); (G.B.); (J.-P.D.); (N.B.)
| | - Nouhaila Bouguiyoud
- INCIA, UMR5287, Centre National de la Recherche Scientifique, 33076 Bordeaux, France; (J.B.-C.); (R.B.); (G.B.); (J.-P.D.); (N.B.)
| | - Giuseppe Di Giovanni
- Laboratory of Neurophysiology, Department of Physiology and Biochemistry, Faculty of Medicine and Surgery, University of Malta, MSD 2080 Msida, Malta;
- School of Biosciences, Neuroscience Division, Cardiff University, Cardiff CF24 4HQ, UK
| | - Daniel Cattaert
- INCIA, UMR5287, Centre National de la Recherche Scientifique, 33076 Bordeaux, France; (J.B.-C.); (R.B.); (G.B.); (J.-P.D.); (N.B.)
- Correspondence: (D.C.); (P.D.D.)
| | - Philippe De Deurwaerdère
- INCIA, UMR5287, Centre National de la Recherche Scientifique, 33076 Bordeaux, France; (J.B.-C.); (R.B.); (G.B.); (J.-P.D.); (N.B.)
- Correspondence: (D.C.); (P.D.D.)
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24
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Wan KY. Synchrony and symmetry-breaking in active flagellar coordination. Philos Trans R Soc Lond B Biol Sci 2020; 375:20190393. [PMID: 31884920 PMCID: PMC7017343 DOI: 10.1098/rstb.2019.0393] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/02/2019] [Indexed: 12/12/2022] Open
Abstract
Living creatures exhibit a remarkable diversity of locomotion mechanisms, evolving structures specialized for interacting with their environment. In the vast majority of cases, locomotor behaviours such as flying, crawling and running are orchestrated by nervous systems. Surprisingly, microorganisms can enact analogous movement gaits for swimming using multiple, fast-moving cellular protrusions called cilia and flagella. Here, I demonstrate intermittency, reversible rhythmogenesis and gait mechanosensitivity in algal flagella, to reveal the active nature of locomotor patterning. In addition to maintaining free-swimming gaits, I show that the algal flagellar apparatus functions as a central pattern generator that encodes the beating of each flagellum in a network in a distinguishable manner. The latter provides a novel symmetry-breaking mechanism for cell reorientation. These findings imply that the capacity to generate and coordinate complex locomotor patterns does not require neural circuitry but rather the minimal ingredients are present in simple unicellular organisms. This article is part of the Theo Murphy meeting issue 'Unity and diversity of cilia in locomotion and transport'.
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Affiliation(s)
- Kirsty Y. Wan
- Living Systems Institute, University of Exeter, Exeter EX4 4QD, UK
- College of Engineering, Mathematics, and Physical Sciences, University of Exeter, Exeter EX4 4QD, UK
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25
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Abstract
Snails, earthworms and flatworms are remarkably different animals, but they all exhibit a very similar mode of early embryogenesis: spiral cleavage. This is one of the most widespread developmental programs in animals, probably ancestral to almost half of the animal phyla, and therefore its study is essential for understanding animal development and evolution. However, our knowledge of spiral cleavage is still in its infancy. Recent technical and conceptual advances, such as the establishment of genome editing and improved phylogenetic resolution, are paving the way for a fresher and deeper look into this fascinating early cleavage mode.
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Affiliation(s)
- José M Martín-Durán
- Queen Mary, University of London, School of Biological and Chemical Sciences, Mile End Road, E1 4NS London, UK
| | - Ferdinand Marlétaz
- Molecular Genetics Unit, Okinawa Institute of Science & Technology, 1919-1, Tancha, Onna 904-0495, Japan
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26
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Wan KY, Hürlimann SK, Fenix AM, McGillivary RM, Makushok T, Burns E, Sheung JY, Marshall WF. Reorganization of complex ciliary flows around regenerating Stentor coeruleus. Philos Trans R Soc Lond B Biol Sci 2019; 375:20190167. [PMID: 31884915 PMCID: PMC7017328 DOI: 10.1098/rstb.2019.0167] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
The phenomenon of ciliary coordination has garnered increasing attention in recent decades and multiple theories have been proposed to explain its occurrence in different biological systems. While hydrodynamic interactions are thought to dictate the large-scale coordinated activity of epithelial cilia for fluid transport, it is rather basal coupling that accounts for synchronous swimming gaits in model microeukaryotes such as Chlamydomonas. Unicellular ciliates present a fascinating yet understudied context in which coordination is found to persist in ciliary arrays positioned across millimetre scales on the same cell. Here, we focus on the ciliate Stentor coeruleus, chosen for its large size, complex ciliary organization, and capacity for cellular regeneration. These large protists exhibit ciliary differentiation between cortical rows of short body cilia used for swimming, and an anterior ring of longer, fused cilia called the membranellar band (MB). The oral cilia in the MB beat metachronously to produce strong feeding currents. Remarkably, upon injury, the MB can be shed and regenerated de novo. Here, we follow and track this developmental sequence in its entirety to elucidate the emergence of coordinated ciliary beating: from band formation, elongation, curling and final migration towards the cell anterior. We reveal a complex interplay between hydrodynamics and ciliary restructuring in Stentor, and highlight for the first time the importance of a ring-like topology for achieving long-range metachronism in ciliated structures. This article is part of the Theo Murphy meeting issue ‘Unity and diversity of cilia in locomotion and transport’.
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Affiliation(s)
- Kirsty Y Wan
- Living Systems Institute, University of Exeter, Stocker Road, Exeter EX4 4QD, UK.,Marine Biological Laboratory, Physiology Course, Woods Hole, MA 02543, USA
| | - Sylvia K Hürlimann
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA 02138, USA.,Marine Biological Laboratory, Physiology Course, Woods Hole, MA 02543, USA
| | - Aidan M Fenix
- Department of Pathology, University of Washington, WA 98109, USA.,Center for Cardiovascular Biology, University of Washington, WA 98109, USA.,Marine Biological Laboratory, Physiology Course, Woods Hole, MA 02543, USA
| | - Rebecca M McGillivary
- Department of Biochemistry and Biophysics, UCSF, San Francisco, CA 94143, USA.,Marine Biological Laboratory, Physiology Course, Woods Hole, MA 02543, USA
| | - Tatyana Makushok
- Department of Biochemistry and Biophysics, UCSF, San Francisco, CA 94143, USA.,Marine Biological Laboratory, Physiology Course, Woods Hole, MA 02543, USA
| | - Evan Burns
- Department of Biology, Vassar College, NY 12604, USA.,Marine Biological Laboratory, Whitman Center, Woods Hole, MA 02543, USA
| | - Janet Y Sheung
- Department of Physics and Astronomy, Vassar College, NY 12604, USA.,Marine Biological Laboratory, Whitman Center, Woods Hole, MA 02543, USA
| | - Wallace F Marshall
- Department of Biochemistry and Biophysics, UCSF, San Francisco, CA 94143, USA.,Marine Biological Laboratory, Physiology Course, Woods Hole, MA 02543, USA
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27
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Abstract
Cilia are specialized cellular organelles that are united in structure and implicated in diverse key life processes across eukaryotes. In both unicellular and multicellular organisms, variations on the same ancestral form mediate sensing, locomotion and the production of physiological flows. As we usher in a new, more interdisciplinary era, the way we study cilia is changing. This special theme issue brings together biologists, biophysicists and mathematicians to highlight the remarkable range of systems in which motile cilia fulfil vital functions, and to inspire and define novel strategies for future research. This article is part of the Theo Murphy meeting issue 'Unity and diversity of cilia in locomotion and transport'.
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Affiliation(s)
- Kirsty Y Wan
- Living Systems Institute, University of Exeter, Stocker Road, Exeter EX4 4QD, UK
| | - Gáspár Jékely
- Living Systems Institute, University of Exeter, Stocker Road, Exeter EX4 4QD, UK
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28
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Marinković M, Berger J, Jékely G. Neuronal coordination of motile cilia in locomotion and feeding. Philos Trans R Soc Lond B Biol Sci 2019; 375:20190165. [PMID: 31884921 PMCID: PMC7017327 DOI: 10.1098/rstb.2019.0165] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
Efficient ciliary locomotion and transport require the coordination of motile cilia. Short-range coordination of ciliary beats can occur by biophysical mechanisms. Long-range coordination across large or disjointed ciliated fields often requires nervous system control and innervation of ciliated cells by ciliomotor neurons. The neuronal control of cilia is best understood in invertebrate ciliated microswimmers, but similar mechanisms may operate in the vertebrate body. Here, we review how the study of aquatic invertebrates contributed to our understanding of the neuronal control of cilia. We summarize the anatomy of ciliomotor systems and the physiological mechanisms that can alter ciliary activity. We also discuss the most well-characterized ciliomotor system, that of the larval annelid Platynereis. Here, pacemaker neurons drive the rhythmic activation of cholinergic and serotonergic ciliomotor neurons to induce ciliary arrests and beating. The Platynereis ciliomotor neurons form a distinct part of the larval nervous system. Similar ciliomotor systems likely operate in other ciliated larvae, such as mollusc veligers. We discuss the possible ancestry and conservation of ciliomotor circuits and highlight how comparative experimental approaches could contribute to a better understanding of the evolution and function of ciliary systems. This article is part of the Theo Murphy meeting issue ‘Unity and diversity of cilia in locomotion and transport’.
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Affiliation(s)
- Milena Marinković
- Living Systems Institute, University of Exeter, Stocker Road, Exeter EX4 4QD, UK
| | - Jürgen Berger
- Max Planck Institute for Developmental Biology, 72076 Tübingen, Germany
| | - Gáspár Jékely
- Living Systems Institute, University of Exeter, Stocker Road, Exeter EX4 4QD, UK
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29
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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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30
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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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31
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Carrillo-Baltodano AM, Boyle MJ, Rice ME, Meyer NP. Developmental architecture of the nervous system in Themiste lageniformis (Sipuncula): New evidence from confocal laser scanning microscopy and gene expression. J Morphol 2019; 280:1628-1650. [PMID: 31487090 DOI: 10.1002/jmor.21054] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2019] [Revised: 07/19/2019] [Accepted: 08/01/2019] [Indexed: 11/09/2022]
Abstract
Sipuncula is a clade of unsegmented marine worms that are currently placed among the basal radiation of conspicuously segmented Annelida. Their new location provides a unique opportunity to reinvestigate the evolution and development of segmented body plans. Neural segmentation is clearly evident during ganglionic ventral nerve cord (VNC) formation across Sedentaria and Errantia, which includes the majority of annelids. However, recent studies show that some annelid taxa outside of Sedentaria and Errantia have a medullary cord, without ganglia, as adults. Importantly, neural development in these taxa is understudied and interpretation can vary widely. For example, reports in sipunculans range from no evidence of segmentation to vestigial segmentation as inferred from a few pairs of serially repeated neuronal cell bodies along the VNC. We investigated patterns of pan-neuronal, neuronal subtype, and axonal markers using immunohistochemistry and whole mount in situ hybridization (WMISH) during neural development in an indirect-developing sipunculan, Themiste lageniformis. Confocal imaging revealed two clusters of 5HT+ neurons, two pairs of FMRF+ neurons, and Tubulin+ peripheral neurites that appear to be serially positioned along the VNC, similar to other sipunculans, to other annelids, and to spiralian taxa outside of Annelida. WMISH of a synaptotagmin1 ortholog in T. lageniformis (Tl-syt1) showed expression throughout the centralized nervous system (CNS), including the VNC where it appears to correlate with mature 5HT+ and FMRF+ neurons. An ortholog of elav1 (Tl-elav1) showed expression in differentiated neurons of the CNS with continuous expression in the VNC, supporting evidence of a medullary cord, and refuting evidence of ontogenetic segmentation during formation of the nervous system. Thus, we conclude that sipunculans do not exhibit any signs of morphological segmentation during development.
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Affiliation(s)
| | - Michael J Boyle
- Smithsonian Institution, Smithsonian Marine Station at Fort Pierce, Fort Pierce, Florida
| | - Mary E Rice
- Smithsonian Institution, Smithsonian Marine Station at Fort Pierce, Fort Pierce, Florida
| | - Néva P Meyer
- Biology Department, Clark University, Worcester, Massachusetts
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32
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Bernardo-Garcia FJ, Syed M, Jékely G, Sprecher SG. Glass confers rhabdomeric photoreceptor identity in Drosophila, but not across all metazoans. EvoDevo 2019; 10:4. [PMID: 30873275 PMCID: PMC6399963 DOI: 10.1186/s13227-019-0117-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2018] [Accepted: 02/15/2019] [Indexed: 12/14/2022] Open
Abstract
Across metazoans, visual systems employ different types of photoreceptor neurons (PRs) to detect light. These include rhabdomeric PRs, which exist in distantly related phyla and possess an evolutionarily conserved phototransduction cascade. While the development of rhabdomeric PRs has been thoroughly studied in the fruit fly Drosophila melanogaster, we still know very little about how they form in other species. To investigate this question, we tested whether the transcription factor Glass, which is crucial for instructing rhabdomeric PR formation in Drosophila, may play a similar role in other metazoans. Glass homologues exist throughout the animal kingdom, indicating that this protein evolved prior to the metazoan radiation. Interestingly, our work indicates that glass is not expressed in rhabdomeric photoreceptors in the planarian Schmidtea mediterranea nor in the annelid Platynereis dumerilii. Combined with a comparative analysis of the Glass DNA-binding domain, our data suggest that the fate of rhabdomeric PRs is controlled by Glass-dependent and Glass-independent mechanisms in different animal clades.
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Affiliation(s)
- F Javier Bernardo-Garcia
- 1Department of Biology, University of Fribourg, Chemin du Musée 10, 1700 Fribourg, Switzerland.,2Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, CA 94158 USA
| | - Maryam Syed
- 1Department of Biology, University of Fribourg, Chemin du Musée 10, 1700 Fribourg, Switzerland
| | - Gáspár Jékely
- 3Living Systems Institute, University of Exeter, Stocker Road, Exeter, EX4 4QD UK
| | - Simon G Sprecher
- 1Department of Biology, University of Fribourg, Chemin du Musée 10, 1700 Fribourg, Switzerland
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33
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Álvarez-Campos P, Kenny NJ, Verdes A, Fernández R, Novo M, Giribet G, Riesgo A. Delegating Sex: Differential Gene Expression in Stolonizing Syllids Uncovers the Hormonal Control of Reproduction. Genome Biol Evol 2019; 11:295-318. [PMID: 30535381 PMCID: PMC6350857 DOI: 10.1093/gbe/evy265] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/09/2018] [Indexed: 12/31/2022] Open
Abstract
Stolonization in syllid annelids is a unique mode of reproduction among animals. During the breeding season, a structure resembling the adult but containing only gametes, called stolon, is formed generally at the posterior end of the animal. When stolons mature, they detach from the adult and gametes are released into the water column. The process is synchronized within each species, and it has been reported to be under environmental and endogenous control, probably via endocrine regulation. To further understand reproduction in syllids and to elucidate the molecular toolkit underlying stolonization, we generated Illumina RNA-seq data from different tissues of reproductive and nonreproductive individuals of Syllis magdalena and characterized gene expression during the stolonization process. Several genes involved in gametogenesis (ovochymase, vitellogenin, testis-specific serine/threonine-kinase), immune response (complement receptor 2), neuronal development (tyrosine-protein kinase Src42A), cell proliferation (alpha-1D adrenergic receptor), and steroid metabolism (hydroxysteroid dehydrogenase 2) were found differentially expressed in the different tissues and conditions analyzed. In addition, our findings suggest that several neurohormones, such as methyl farnesoate, dopamine, and serotonin, might trigger stolon formation, the correct maturation of gametes and the detachment of stolons when gametogenesis ends. The process seems to be under circadian control, as indicated by the expression patterns of r-opsins. Overall, our results shed light into the genes that orchestrate the onset of gamete formation and improve our understanding of how some hormones, previously reported to be involved in reproduction and metamorphosis processes in other invertebrates, seem to also regulate reproduction via stolonization.
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Affiliation(s)
- Patricia Álvarez-Campos
- Facultad de Ciencias, Departamento de Biología (Zoología), Universidad Autónoma de Madrid, Spain
- Museum of Comparative Zoology, Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, Massachusetts
- Department of Life Sciences, The Natural History Museum of London, London, United Kingdom
- Department of Biological & Medical Sciences, Oxford Brookes University, Headington Campus, Gipsy Lane, Oxford, United Kingdom
| | - Nathan J Kenny
- Department of Life Sciences, The Natural History Museum of London, London, United Kingdom
| | - Aida Verdes
- Facultad de Ciencias, Departamento de Biología (Zoología), Universidad Autónoma de Madrid, Spain
- Department of Biology, The Graduate Center, City University of New York
- Sackler Institute for Comparative Genomics, American Museum of Natural History, New York, New York
| | - Rosa Fernández
- Bioinformatics & Genomics Unit, Center for Genomic Regulation, Barcelona, Spain
| | - Marta Novo
- Facultad de Biología, Departamento de Biodiversidad, Ecología y Evolución, Universidad Complutense de Madrid, Spain
| | - Gonzalo Giribet
- Museum of Comparative Zoology, Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, Massachusetts
| | - Ana Riesgo
- Department of Biology, The Graduate Center, City University of New York
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Bezares-Calderón LA, Berger J, Jasek S, Verasztó C, Mendes S, Gühmann M, Almeda R, Shahidi R, Jékely G. Neural circuitry of a polycystin-mediated hydrodynamic startle response for predator avoidance. eLife 2018; 7:36262. [PMID: 30547885 PMCID: PMC6294549 DOI: 10.7554/elife.36262] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2018] [Accepted: 11/16/2018] [Indexed: 12/19/2022] Open
Abstract
Startle responses triggered by aversive stimuli including predators are widespread across animals. These coordinated whole-body actions require the rapid and simultaneous activation of a large number of muscles. Here we study a startle response in a planktonic larva to understand the whole-body circuit implementation of the behaviour. Upon encountering water vibrations, larvae of the annelid Platynereis close their locomotor cilia and simultaneously raise the parapodia. The response is mediated by collar receptor neurons expressing the polycystins PKD1-1 and PKD2-1. CRISPR-generated PKD1-1 and PKD2-1 mutant larvae do not startle and fall prey to a copepod predator at a higher rate. Reconstruction of the whole-body connectome of the collar-receptor-cell circuitry revealed converging feedforward circuits to the ciliary bands and muscles. The wiring diagram suggests circuit mechanisms for the intersegmental and left-right coordination of the response. Our results reveal how polycystin-mediated mechanosensation can trigger a coordinated whole-body effector response involved in predator avoidance.
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Affiliation(s)
- Luis A Bezares-Calderón
- Living Systems Institute, University of Exeter, Exeter, United Kingdom.,Max Planck Institute for Developmental Biology, Tübingen, Germany
| | - Jürgen Berger
- Max Planck Institute for Developmental Biology, Tübingen, Germany
| | - Sanja Jasek
- Living Systems Institute, University of Exeter, Exeter, United Kingdom.,Max Planck Institute for Developmental Biology, Tübingen, Germany
| | - Csaba Verasztó
- Living Systems Institute, University of Exeter, Exeter, United Kingdom.,Max Planck Institute for Developmental Biology, Tübingen, Germany
| | - Sara Mendes
- Max Planck Institute for Developmental Biology, Tübingen, Germany
| | - Martin Gühmann
- Max Planck Institute for Developmental Biology, Tübingen, Germany
| | - Rodrigo Almeda
- Centre for Ocean Life, Technical University of Denmark, Denmark, Kingdom of Denmark
| | - Réza Shahidi
- Living Systems Institute, University of Exeter, Exeter, United Kingdom.,Max Planck Institute for Developmental Biology, Tübingen, Germany
| | - Gáspár Jékely
- Living Systems Institute, University of Exeter, Exeter, United Kingdom.,Max Planck Institute for Developmental Biology, Tübingen, Germany
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35
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Wan KY. Coordination of eukaryotic cilia and flagella. Essays Biochem 2018; 62:829-838. [PMID: 30464007 PMCID: PMC6281475 DOI: 10.1042/ebc20180029] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2018] [Revised: 10/04/2018] [Accepted: 10/08/2018] [Indexed: 12/14/2022]
Abstract
Propulsion by slender cellular appendages called cilia and flagella is an ancient means of locomotion. Unicellular organisms evolved myriad strategies to propel themselves in fluid environments, often involving significant differences in flagella number, localisation and modes of actuation. Remarkably, these appendages are highly conserved, occurring in many complex organisms such as humans, where they may be found generating physiological flows when attached to surfaces (e.g. airway epithelial cilia), or else conferring motility to male gametes (e.g. undulations of sperm flagella). Where multiple cilia arise, their movements are often observed to be highly coordinated. Here I review the two main mechanisms for motile cilia coordination, namely, intracellular and hydrodynamic, and discuss their relative importance in different ciliary systems.
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Affiliation(s)
- Kirsty Y Wan
- Living Systems Institute, University of Exeter, Exeter, U.K.
- College of Engineering Mathematics and Physical Sciences, University of Exeter, Exeter, U.K
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36
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Mulcahy B, Witvliet D, Holmyard D, Mitchell J, Chisholm AD, Meirovitch Y, Samuel ADT, Zhen M. A Pipeline for Volume Electron Microscopy of the Caenorhabditis elegans Nervous System. Front Neural Circuits 2018; 12:94. [PMID: 30524248 PMCID: PMC6262311 DOI: 10.3389/fncir.2018.00094] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2018] [Accepted: 10/08/2018] [Indexed: 01/01/2023] Open
Abstract
The “connectome,” a comprehensive wiring diagram of synaptic connectivity, is achieved through volume electron microscopy (vEM) analysis of an entire nervous system and all associated non-neuronal tissues. White et al. (1986) pioneered the fully manual reconstruction of a connectome using Caenorhabditis elegans. Recent advances in vEM allow mapping new C. elegans connectomes with increased throughput, and reduced subjectivity. Current vEM studies aim to not only fill the remaining gaps in the original connectome, but also address fundamental questions including how the connectome changes during development, the nature of individuality, sexual dimorphism, and how genetic and environmental factors regulate connectivity. Here we describe our current vEM pipeline and projected improvements for the study of the C. elegans nervous system and beyond.
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Affiliation(s)
- Ben Mulcahy
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, ON, Canada
| | - Daniel Witvliet
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, ON, Canada.,Department of Molecular Genetics, University of Toronto, Toronto, ON, Canada
| | - Douglas Holmyard
- Department of Pathology and Laboratory Medicine, Mount Sinai Hospital, Toronto, ON, Canada.,Nanoscale Biomedical Imaging Facility, The Hospital for Sick Children, Peter Gilgan Centre for Research and Learning, Toronto, ON, Canada
| | - James Mitchell
- Center for Brain Science, Department of Physics, Harvard University, Cambridge, MA, United States
| | - Andrew D Chisholm
- Section of Cell and Developmental Biology, Division of Biological Sciences, University of California, San Diego, La Jolla, CA, United States
| | - Yaron Meirovitch
- Department of Physiology, University of Toronto, Toronto, ON, Canada
| | - Aravinthan D T Samuel
- Center for Brain Science, Department of Physics, Harvard University, Cambridge, MA, United States
| | - Mei Zhen
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, ON, Canada.,Department of Molecular Genetics, University of Toronto, Toronto, ON, Canada.,Department of Physiology, University of Toronto, Toronto, ON, Canada.,Department of Cell and Systems Biology, University of Toronto, Toronto, ON, Canada
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37
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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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38
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Verasztó C, Gühmann M, Jia H, Rajan VBV, Bezares-Calderón LA, Piñeiro-Lopez C, Randel N, Shahidi R, Michiels NK, Yokoyama S, Tessmar-Raible K, Jékely G. Ciliary and rhabdomeric photoreceptor-cell circuits form a spectral depth gauge in marine zooplankton. eLife 2018; 7:36440. [PMID: 29809157 PMCID: PMC6019069 DOI: 10.7554/elife.36440] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2018] [Accepted: 05/28/2018] [Indexed: 02/02/2023] Open
Abstract
Ciliary and rhabdomeric photoreceptor cells represent two main lines of photoreceptor-cell evolution in animals. The two cell types coexist in some animals, however how these cells functionally integrate is unknown. We used connectomics to map synaptic paths between ciliary and rhabdomeric photoreceptors in the planktonic larva of the annelid Platynereis and found that ciliary photoreceptors are presynaptic to the rhabdomeric circuit. The behaviors mediated by the ciliary and rhabdomeric cells also interact hierarchically. The ciliary photoreceptors are UV-sensitive and mediate downward swimming in non-directional UV light, a behavior absent in ciliary-opsin knockout larvae. UV avoidance overrides positive phototaxis mediated by the rhabdomeric eyes such that vertical swimming direction is determined by the ratio of blue/UV light. Since this ratio increases with depth, Platynereis larvae may use it as a depth gauge during vertical migration. Our results revealed a functional integration of ciliary and rhabdomeric photoreceptor cells in a zooplankton larva.
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Affiliation(s)
- Csaba Verasztó
- Max Planck Institute for Developmental Biology, Tübingen, Germany.,Living Systems Institute, University of Exeter, Exeter, United Kingdom
| | - Martin Gühmann
- Max Planck Institute for Developmental Biology, Tübingen, Germany
| | - Huiyong Jia
- Department of Biology, Emory University, Atlanta, United States
| | | | - Luis A Bezares-Calderón
- Max Planck Institute for Developmental Biology, Tübingen, Germany.,Living Systems Institute, University of Exeter, Exeter, United Kingdom
| | | | - Nadine Randel
- Max Planck Institute for Developmental Biology, Tübingen, Germany
| | - Réza Shahidi
- Max Planck Institute for Developmental Biology, Tübingen, Germany.,Living Systems Institute, University of Exeter, Exeter, United Kingdom
| | - Nico K Michiels
- Department of Biology, University of Tübingen, Tübingen, Germany
| | - Shozo Yokoyama
- Department of Biology, Emory University, Atlanta, United States
| | | | - Gáspár Jékely
- Max Planck Institute for Developmental Biology, Tübingen, Germany.,Living Systems Institute, University of Exeter, Exeter, United Kingdom
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39
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Williams EA, Verasztó C, Jasek S, Conzelmann M, Shahidi R, Bauknecht P, Mirabeau O, Jékely G. Synaptic and peptidergic connectome of a neurosecretory center in the annelid brain. eLife 2017; 6:26349. [PMID: 29199953 PMCID: PMC5747525 DOI: 10.7554/elife.26349] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2017] [Accepted: 12/02/2017] [Indexed: 12/15/2022] Open
Abstract
Neurosecretory centers in animal brains use peptidergic signaling to influence physiology and behavior. Understanding neurosecretory center function requires mapping cell types, synapses, and peptidergic networks. Here we use transmission electron microscopy and gene expression mapping to analyze the synaptic and peptidergic connectome of an entire neurosecretory center. We reconstructed 78 neurosecretory neurons and mapped their synaptic connectivity in the brain of larval Platynereis dumerilii, a marine annelid. These neurons form an anterior neurosecretory center expressing many neuropeptides, including hypothalamic peptide orthologs and their receptors. Analysis of peptide-receptor pairs in spatially mapped single-cell transcriptome data revealed sparsely connected networks linking specific neuronal subsets. We experimentally analyzed one peptide-receptor pair and found that a neuropeptide can couple neurosecretory and synaptic brain signaling. Our study uncovered extensive networks of peptidergic signaling within a neurosecretory center and its connection to the synaptic brain.
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Affiliation(s)
| | - Csaba Verasztó
- Max Planck Institute for Developmental Biology, Tübingen, Germany
| | - Sanja Jasek
- Max Planck Institute for Developmental Biology, Tübingen, Germany
| | | | - Réza Shahidi
- Max Planck Institute for Developmental Biology, Tübingen, Germany.,Living Systems Institute, University of Exeter, Exeter, United Kingdom
| | | | - Olivier Mirabeau
- Genetics and Biology of Cancers Unit, Institut Curie, INSERM U830, Paris Sciences et Lettres Research University, Paris, France
| | - Gáspár Jékely
- Max Planck Institute for Developmental Biology, Tübingen, Germany.,Living Systems Institute, University of Exeter, Exeter, United Kingdom
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40
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Abstract
A map of a neuronal circuit in a marine worm reveals how simple networks of neurons can control behavior.
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Affiliation(s)
- Yee Lian Chew
- MRC Laboratory of Molecular Biology, University of Cambridge, Cambridge, United Kingdom
| | - William R Schafer
- MRC Laboratory of Molecular Biology, University of Cambridge, Cambridge, United Kingdom
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