1
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Skokan TD, Hobmayer B, McKinley KL, Vale RD. Mechanical stretch regulates macropinocytosis in Hydra vulgaris. Mol Biol Cell 2024; 35:br9. [PMID: 38265917 PMCID: PMC10916863 DOI: 10.1091/mbc.e22-02-0065] [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: 03/07/2022] [Revised: 01/12/2024] [Accepted: 01/19/2024] [Indexed: 01/26/2024] Open
Abstract
Cells rely on a diverse array of engulfment processes to sense, exploit, and adapt to their environments. Among these, macropinocytosis enables indiscriminate and rapid uptake of large volumes of fluid and membrane, rendering it a highly versatile engulfment strategy. Much of the molecular machinery required for macropinocytosis has been well established, yet how this process is regulated in the context of organs and organisms remains poorly understood. Here, we report the discovery of extensive macropinocytosis in the outer epithelium of the cnidarian Hydra vulgaris. Exploiting Hydra's relatively simple body plan, we developed approaches to visualize macropinocytosis over extended periods of time, revealing constitutive engulfment across the entire body axis. We show that the direct application of planar stretch leads to calcium influx and the inhibition of macropinocytosis. Finally, we establish a role for stretch-activated channels in inhibiting this process. Together, our approaches provide a platform for the mechanistic dissection of constitutive macropinocytosis in physiological contexts and highlight a potential role for macropinocytosis in responding to cell surface tension.
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Affiliation(s)
- Taylor D. Skokan
- Howard Hughes Medical Institute and Department of Cellular and Molecular Pharmacology, University of California, San Francisco, San Francisco, CA 94158
| | - Bert Hobmayer
- Department of Zoology and Centre for Molecular Biosciences Innsbruck (CMBI), University of Innsbruck, Technikerstr. 25, A-6020 Innsbruck, Austria
| | - Kara L. McKinley
- Howard Hughes Medical Institute and Department of Stem Cell and Regenerative Biology, Harvard University, Cambridge, MA 02138
| | - Ronald D. Vale
- Howard Hughes Medical Institute and Department of Cellular and Molecular Pharmacology, University of California, San Francisco, San Francisco, CA 94158
- Howard Hughes Medical Institute Janelia Research Campus, Ashburn, VA, 20147
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2
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Goel T, Adams EM, Bialas AL, Tran CM, Rowe T, Martin S, Chandler M, Schubert J, Diamond PH, Collins EMS. Nonlinear elasticity and short-range mechanical coupling govern the rate and symmetry of mouth opening in Hydra. Proc Biol Sci 2024; 291:20232123. [PMID: 38378148 PMCID: PMC10878823 DOI: 10.1098/rspb.2023.2123] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2023] [Accepted: 01/18/2024] [Indexed: 02/22/2024] Open
Abstract
Hydra has a tubular bilayered epithelial body column with a dome-shaped head on one end and a foot on the other. Hydra lacks a permanent mouth: its head epithelium is sealed. Upon neuronal activation, a mouth opens at the apex of the head which can exceed the body column diameter in seconds, allowing Hydra to ingest prey larger than itself. While the kinematics of mouth opening are well characterized, the underlying mechanism is unknown. We show that Hydra mouth opening is generated by independent local contractions that require tissue-level coordination. We model the head epithelium as an active viscoelastic nonlinear spring network. The model reproduces the size, timescale and symmetry of mouth opening. It shows that radial contractions, travelling inwards from the outer boundary of the head, pull the mouth open. Nonlinear elasticity makes mouth opening larger and faster, contrary to expectations. The model correctly predicts changes in mouth shape in response to external forces. By generating innervated : nerve-free chimera in experiments and simulations, we show that nearest-neighbour mechanical signalling suffices to coordinate mouth opening. Hydra mouth opening shows that in the absence of long-range chemical or neuronal signals, short-range mechanical coupling is sufficient to produce long-range order in tissue deformations.
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Affiliation(s)
- Tapan Goel
- Department of Physics, University of California San Diego, La Jolla, CA 92093, USA
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA 30332, USA
- Department of Biology, University of Maryland, College Park, MD 20742, USA
| | - Ellen M. Adams
- Department of Biology, Swarthmore College, Swarthmore, PA 19081, USA
| | - April L. Bialas
- Department of Biology, Swarthmore College, Swarthmore, PA 19081, USA
| | - Cassidy M. Tran
- Division of Biological Sciences, University of California San Diego, La Jolla, CA 92093, USA
| | - Trevor Rowe
- Department of Physics, University of California San Diego, La Jolla, CA 92093, USA
| | - Sara Martin
- Department of Biology, Swarthmore College, Swarthmore, PA 19081, USA
| | - Maia Chandler
- Department of Biology, Swarthmore College, Swarthmore, PA 19081, USA
| | - Johanna Schubert
- Department of Biology, Swarthmore College, Swarthmore, PA 19081, USA
| | - Patrick H. Diamond
- Department of Physics, University of California San Diego, La Jolla, CA 92093, USA
| | - Eva-Maria S. Collins
- Department of Physics, University of California San Diego, La Jolla, CA 92093, USA
- Department of Biology, Swarthmore College, Swarthmore, PA 19081, USA
- Department of Neuroscience, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
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3
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Keramidioti A, Schneid S, Busse C, Cramer von Laue C, Bertulat B, Salvenmoser W, Hess M, Alexandrova O, Glauber KM, Steele RE, Hobmayer B, Holstein TW, David CN. A new look at the architecture and dynamics of the Hydra nerve net. eLife 2024; 12:RP87330. [PMID: 38407174 PMCID: PMC10942621 DOI: 10.7554/elife.87330] [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] [Indexed: 02/27/2024] Open
Abstract
The Hydra nervous system is the paradigm of a 'simple nerve net'. Nerve cells in Hydra, as in many cnidarian polyps, are organized in a nerve net extending throughout the body column. This nerve net is required for control of spontaneous behavior: elimination of nerve cells leads to polyps that do not move and are incapable of capturing and ingesting prey (Campbell, 1976). We have re-examined the structure of the Hydra nerve net by immunostaining fixed polyps with a novel antibody that stains all nerve cells in Hydra. Confocal imaging shows that there are two distinct nerve nets, one in the ectoderm and one in the endoderm, with the unexpected absence of nerve cells in the endoderm of the tentacles. The nerve nets in the ectoderm and endoderm do not contact each other. High-resolution TEM (transmission electron microscopy) and serial block face SEM (scanning electron microscopy) show that the nerve nets consist of bundles of parallel overlapping neurites. Results from transgenic lines show that neurite bundles include different neural circuits and hence that neurites in bundles require circuit-specific recognition. Nerve cell-specific innexins indicate that gap junctions can provide this specificity. The occurrence of bundles of neurites supports a model for continuous growth and differentiation of the nerve net by lateral addition of new nerve cells to the existing net. This model was confirmed by tracking newly differentiated nerve cells.
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Affiliation(s)
- Athina Keramidioti
- Department of Biology, Ludwig-Maximilians-University MunichMartinsriedGermany
| | - Sandra Schneid
- Department of Biology, Ludwig-Maximilians-University MunichMartinsriedGermany
| | - Christina Busse
- Department of Biology, Ludwig-Maximilians-University MunichMartinsriedGermany
| | | | - Bianca Bertulat
- Centre for Organismal Studies (COS) Heidelberg, Heidelberg UniversityHeidelbergGermany
| | - Willi Salvenmoser
- Department of Zoology and Center for Molecular Biosciences Innsbruck (CMBI), University of InnsbruckInnsbruckAustria
| | - Martin Hess
- Department of Biology, Ludwig-Maximilians-University MunichMartinsriedGermany
| | - Olga Alexandrova
- Department of Biology, Ludwig-Maximilians-University MunichMartinsriedGermany
| | - Kristine M Glauber
- Department of Biological Chemistry, University of CaliforniaIrvineUnited States
| | - Robert E Steele
- Department of Biological Chemistry, University of CaliforniaIrvineUnited States
| | - Bert Hobmayer
- Department of Zoology and Center for Molecular Biosciences Innsbruck (CMBI), University of InnsbruckInnsbruckAustria
| | - Thomas W Holstein
- Centre for Organismal Studies (COS) Heidelberg, Heidelberg UniversityHeidelbergGermany
| | - Charles N David
- Department of Biology, Ludwig-Maximilians-University MunichMartinsriedGermany
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4
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Hanson A. On being a Hydra with, and without, a nervous system: what do neurons add? Anim Cogn 2023; 26:1799-1816. [PMID: 37540280 PMCID: PMC10770230 DOI: 10.1007/s10071-023-01816-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2023] [Revised: 07/05/2023] [Accepted: 07/27/2023] [Indexed: 08/05/2023]
Abstract
The small freshwater cnidarian Hydra has been the subject of scientific inquiry for over 300 years due to its remarkable regenerative capacities and apparent immortality. More recently, Hydra has been recognized as an excellent model system within neuroscience because of its small size, transparency, and simple nervous system, which allow high-resolution imaging of its entire nerve net while behaving. In less than a decade, studies of Hydra's nervous system have yielded insights into the activity of neural circuits in vivo unobtainable in most other animals. In addition to these unique attributes, there is yet another lesser-known feature of Hydra that makes it even more intriguing: it does not require its neural hardware to live. The extraordinary ability to survive the removal and replacement of its entire nervous system makes Hydra uniquely suited to address the question of what neurons add to an extant organism. Here, I will review what early work on nerve-free Hydra reveals about the potential role of the nervous system in these animals and point towards future directions for this work.
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Affiliation(s)
- Alison Hanson
- Department of Biological Sciences, Neurotechnology Center, Columbia University, New York, NY, USA.
- Department of Psychiatry, New York State Psychiatric Institute, Columbia University, New York, NY, USA.
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5
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Brooun M, Salvenmoser W, Dana C, Sudol M, Steele R, Hobmayer B, McNeill H. The Hippo pathway regulates axis formation and morphogenesis in Hydra. Proc Natl Acad Sci U S A 2022; 119:e2203257119. [PMID: 35858299 PMCID: PMC9304002 DOI: 10.1073/pnas.2203257119] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2022] [Accepted: 05/25/2022] [Indexed: 11/18/2022] Open
Abstract
How did cells of early metazoan organisms first organize themselves to form a body axis? The canonical Wnt pathway has been shown to be sufficient for induction of axis in Cnidaria, a sister group to Bilateria, and is important in bilaterian axis formation. Here, we provide experimental evidence that in cnidarian Hydra the Hippo pathway regulates the formation of a new axis during budding upstream of the Wnt pathway. The transcriptional target of the Hippo pathway, the transcriptional coactivator YAP, inhibits the initiation of budding in Hydra and is regulated by Hydra LATS. In addition, we show functions of the Hippo pathway in regulation of actin organization and cell proliferation in Hydra. We hypothesize that the Hippo pathway served as a link between continuous cell division, cell density, and axis formation early in metazoan evolution.
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Affiliation(s)
- Maria Brooun
- Lunenfeld-Tanenbaum Research Institute, Toronto, ON, M5G 1X5, Canada
| | - Willi Salvenmoser
- Department of Zoology, Center for Molecular Biosciences Innsbruck, University of Innsbruck, A-6020 Innsbruck, Austria
| | - Catherine Dana
- Department of Biological Chemistry, School of Medicine, University of California, Irvine, CA 92697-1700
| | - Marius Sudol
- Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, NY 10029
| | - Robert Steele
- Department of Biological Chemistry, School of Medicine, University of California, Irvine, CA 92697-1700
| | - Bert Hobmayer
- Department of Zoology, Center for Molecular Biosciences Innsbruck, University of Innsbruck, A-6020 Innsbruck, Austria
| | - Helen McNeill
- Department of Developmental Biology, Washington University School of Medicine, St. Louis, MO 63110-1093
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6
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Skokan TD, Vale RD, McKinley KL. Cell Sorting in Hydra vulgaris Arises from Differing Capacities for Epithelialization between Cell Types. Curr Biol 2020; 30:3713-3723.e3. [PMID: 32795440 PMCID: PMC7541579 DOI: 10.1016/j.cub.2020.07.035] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2020] [Revised: 07/05/2020] [Accepted: 07/09/2020] [Indexed: 12/22/2022]
Abstract
Hydra vulgaris exhibits a remarkable capacity to reassemble its body plan from a disordered aggregate of cells. Reassembly begins by sorting two epithelial cell types, endoderm and ectoderm, into inner and outer layers, respectively. The cellular features and behaviors that distinguish ectodermal and endodermal lineages to drive sorting have not been fully elucidated. To dissect this process, we use micromanipulation to position single cells of diverse lineages on the surface of defined multicellular aggregates and monitor sorting outcomes by live imaging. Although sorting has previously been attributed to intrinsic differences between the epithelial lineages, we find that single cells of all lineages sort to the interior of ectodermal aggregates, including single ectodermal cells. This reveals that cells of the same lineage can adopt opposing positions when sorting as individuals or a collective. Ectodermal cell collectives adopt their position at the aggregate exterior by rapidly reforming an epithelium that engulfs cells adhered to its surface through a collective spreading behavior. In contrast, aggregated endodermal cells persistently lose epithelial features. These non-epithelialized aggregates, like isolated cells of all lineages, are adherent passengers for engulfment by the ectodermal epithelium. We find that collective spreading of the ectoderm and persistent de-epithelialization in the endoderm also arise during local wounding in Hydra, suggesting that Hydra's wound-healing and self-organization capabilities may employ similar mechanisms. Together, our data suggest that differing propensities for epithelialization can sort cell types into distinct compartments to build and restore complex tissue architecture.
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Affiliation(s)
- Taylor D Skokan
- Howard Hughes Medical Institute and Department of Cellular and Molecular Pharmacology, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Ronald D Vale
- Howard Hughes Medical Institute and Department of Cellular and Molecular Pharmacology, University of California, San Francisco, San Francisco, CA 94158, USA; Howard Hughes Medical Institute Janelia Research Campus, Ashburn, VA 20147, USA.
| | - Kara L McKinley
- Howard Hughes Medical Institute and Department of Cellular and Molecular Pharmacology, University of California, San Francisco, San Francisco, CA 94158, USA.
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7
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Schenkelaars Q, Perez-Cortes D, Perruchoud C, Galliot B. The polymorphism of Hydra microsatellite sequences provides strain-specific signatures. PLoS One 2020; 15:e0230547. [PMID: 32986740 PMCID: PMC7521734 DOI: 10.1371/journal.pone.0230547] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2020] [Accepted: 09/04/2020] [Indexed: 11/18/2022] Open
Abstract
Hydra are freshwater polyps widely studied for their amazing regenerative capacity, adult stem cell populations, low senescence and value as ecotoxicological marker. Many wild-type strains of H. vulgaris have been collected worldwide and maintained effectively under laboratory conditions by asexual reproduction, while stable transgenic lines have been continuously produced since 2006. Efforts are now needed to ensure the genetic characterization of all these strains, which despite similar morphologies, show significant variability in their response to gene expression silencing procedures, pharmacological treatments or environmental conditions. Here, we established a rapid and reliable procedure at the single polyp level to produce via PCR amplification of three distinct microsatellite sequences molecular signatures that distinguish between Hydra strains and species. The TG-rich region of an uncharacterized gene (ms-c25145) helps to distinguish between Eurasian H. vulgaris-Pallas strains (Hm-105, Basel1, Basel2 and reg-16), between Eurasian and North American H. vulgaris strains (H. carnea, AEP), and between the H. vulgaris and H. oligactis species. The AT-rich microsatellite sequences located in the AIP gene (Aryl Hydrocarbon Receptor Interaction Protein, ms-AIP) also differ between Eurasian and North American H. vulgaris strains. Finally, the AT-rich microsatellite located in the Myb-Like cyclin D-binding transcription factor1 gene (ms-DMTF1) gene helps to distinguish certain transgenic AEP lines. This study shows that the analysis of microsatellite sequences, which is capable of tracing genomic variations between closely related lineages of Hydra, provides a sensitive and robust tool for characterizing the Hydra strains.
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Affiliation(s)
- Quentin Schenkelaars
- Department of Genetics and Evolution, Institute of Genetics and Genomics in Geneva (iGE3), University of Geneva, Geneva, Switzerland
| | - Diego Perez-Cortes
- Department of Genetics and Evolution, Institute of Genetics and Genomics in Geneva (iGE3), University of Geneva, Geneva, Switzerland
| | - Chrystelle Perruchoud
- Department of Genetics and Evolution, Institute of Genetics and Genomics in Geneva (iGE3), University of Geneva, Geneva, Switzerland
| | - Brigitte Galliot
- Department of Genetics and Evolution, Institute of Genetics and Genomics in Geneva (iGE3), University of Geneva, Geneva, Switzerland
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8
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Goel T, Wang R, Martin S, Lanphear E, Collins EMS. Linalool acts as a fast and reversible anesthetic in Hydra. PLoS One 2019; 14:e0224221. [PMID: 31648269 PMCID: PMC6812832 DOI: 10.1371/journal.pone.0224221] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2019] [Accepted: 10/08/2019] [Indexed: 01/23/2023] Open
Abstract
The ability to make transgenic Hydra lines has allowed for quantitative in vivo studies of Hydra regeneration and physiology. These studies commonly include excision, grafting and transplantation experiments along with high-resolution imaging of live animals, which can be challenging due to the animal’s response to touch and light stimuli. While various anesthetics have been used in Hydra studies, they tend to be toxic over the course of a few hours or their long-term effects on animal health are unknown. Here, we show that the monoterpenoid alcohol linalool is a useful anesthetic for Hydra. Linalool is easy to use, non-toxic, fast acting, and reversible. It has no detectable long-term effects on cell viability or cell proliferation. We demonstrate that the same animal can be immobilized in linalool multiple times at intervals of several hours for repeated imaging over 2–3 days. This uniquely allows for in vivo imaging of dynamic processes such as head regeneration. We directly compare linalool to currently used anesthetics and show its superior performance. Linalool will be a useful tool for tissue manipulation and imaging in Hydra research in both research and teaching contexts.
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Affiliation(s)
- Tapan Goel
- Department of Physics, University of California San Diego, La Jolla, CA, United States of America
- Department of Biology, Swarthmore College, Swarthmore, PA, United States of America
| | - Rui Wang
- Department of Biology, Swarthmore College, Swarthmore, PA, United States of America
- Department of Bioengineering, University of California San Diego, La Jolla, CA, United States of America
| | - Sara Martin
- Department of Biology, Swarthmore College, Swarthmore, PA, United States of America
| | - Elizabeth Lanphear
- Department of Biology, Swarthmore College, Swarthmore, PA, United States of America
| | - Eva-Maria S. Collins
- Department of Physics, University of California San Diego, La Jolla, CA, United States of America
- Department of Biology, Swarthmore College, Swarthmore, PA, United States of America
- * E-mail:
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9
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Steele RE, Updegrove MD, Kirolos SA, Mowery L, Martínez DE, Bryant PJ. Reproductive Bet-Hedging and Existence in Vernal Pools as Components of Hydra Life History. THE BIOLOGICAL BULLETIN 2019; 237:111-118. [PMID: 31714853 DOI: 10.1086/705161] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Despite the fact that Hydra has been studied for more than 200 years, we know surprisingly little about its life history. We show that Hydra vulgaris embryos hatch sporadically over a period ranging from a few days to nine months. We also report, for what seems to be the first time, the presence of Hydra in a vernal pool. Phylogenetic analysis and sexual crossing show that this Hydra is a member of the cosmopolitan Vulgaris clade and is not reproductively isolated from other members of the clade. Our findings lead us to hypothesize that Hydra evolved in an unstable freshwater habitat in which survival required that its life cycle include the use of a bet-hedging reproductive strategy and the formation of an embryo that is desiccation resistant and that can remain dormant for long periods of time.
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10
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Siebert S, Farrell JA, Cazet JF, Abeykoon Y, Primack AS, Schnitzler CE, Juliano CE. Stem cell differentiation trajectories in Hydra resolved at single-cell resolution. Science 2019; 365:eaav9314. [PMID: 31346039 PMCID: PMC7104783 DOI: 10.1126/science.aav9314] [Citation(s) in RCA: 207] [Impact Index Per Article: 34.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2018] [Accepted: 06/11/2019] [Indexed: 12/31/2022]
Abstract
The adult Hydra polyp continually renews all of its cells using three separate stem cell populations, but the genetic pathways enabling this homeostatic tissue maintenance are not well understood. We sequenced 24,985 Hydra single-cell transcriptomes and identified the molecular signatures of a broad spectrum of cell states, from stem cells to terminally differentiated cells. We constructed differentiation trajectories for each cell lineage and identified gene modules and putative regulators expressed along these trajectories, thus creating a comprehensive molecular map of all developmental lineages in the adult animal. In addition, we built a gene expression map of the Hydra nervous system. Our work constitutes a resource for addressing questions regarding the evolution of metazoan developmental processes and nervous system function.
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Affiliation(s)
- Stefan Siebert
- Department of Molecular and Cellular Biology, University of California, Davis, CA, USA.
| | - Jeffrey A Farrell
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA, USA
| | - Jack F Cazet
- Department of Molecular and Cellular Biology, University of California, Davis, CA, USA
| | - Yashodara Abeykoon
- Department of Molecular and Cellular Biology, University of California, Davis, CA, USA
| | - Abby S Primack
- Department of Molecular and Cellular Biology, University of California, Davis, CA, USA
| | - Christine E Schnitzler
- Whitney Laboratory for Marine Bioscience and Department of Biology, University of Florida, St. Augustine, FL, USA
| | - Celina E Juliano
- Department of Molecular and Cellular Biology, University of California, Davis, CA, USA.
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11
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Transgenesis in Hydra to characterize gene function and visualize cell behavior. Nat Protoc 2019; 14:2069-2090. [DOI: 10.1038/s41596-019-0173-3] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2018] [Accepted: 04/04/2019] [Indexed: 12/13/2022]
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12
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Regionalized nervous system in Hydra and the mechanism of its development. Gene Expr Patterns 2019; 31:42-59. [PMID: 30677493 DOI: 10.1016/j.gep.2019.01.003] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2018] [Accepted: 01/15/2019] [Indexed: 12/15/2022]
Abstract
The last common ancestor of Bilateria and Cnidaria is considered to develop a nervous system over 500 million years ago. Despite the long course of evolution, many of the neuron-related genes, which are active in Bilateria, are also found in the cnidarian Hydra. Thus, Hydra is a good model to study the putative primitive nervous system in the last common ancestor that had the great potential to evolve to a more advanced one. Regionalization of the nervous system is one of the advanced features of bilaterian nervous system. Although a regionalized nervous system is already known to be present in Hydra, its developmental mechanisms are poorly understood. In this study we show how it is formed and maintained, focusing on the neuropeptide Hym-176 gene and its paralogs. First, we demonstrate that four axially localized neuron subsets that express different combination of the neuropeptide Hym-176 gene and its paralogs cover almost an entire body, forming a regionalized nervous system in Hydra. Second, we show that positional information governed by the Wnt signaling pathway plays a key role in determining the regional specificity of the neuron subsets as is the case in bilaterians. Finally, we demonstrated two basic mechanisms, regionally restricted new differentiation and phenotypic conversion, both of which are in part conserved in bilaterians, are involved in maintaining boundaries between the neuron subsets. Therefore, this study is the first comprehensive analysis of the anatomy and developmental regulation of the divergently evolved and axially regionalized peptidergic nervous system in Hydra, implicating an ancestral origin of neural regionalization.
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13
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Leung MCK, Procter AC, Goldstone JV, Foox J, DeSalle R, Mattingly CJ, Siddall ME, Timme-Laragy AR. Applying evolutionary genetics to developmental toxicology and risk assessment. Reprod Toxicol 2017; 69:174-186. [PMID: 28267574 PMCID: PMC5829367 DOI: 10.1016/j.reprotox.2017.03.003] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2016] [Revised: 02/27/2017] [Accepted: 03/02/2017] [Indexed: 12/26/2022]
Abstract
Evolutionary thinking continues to challenge our views on health and disease. Yet, there is a communication gap between evolutionary biologists and toxicologists in recognizing the connections among developmental pathways, high-throughput screening, and birth defects in humans. To increase our capability in identifying potential developmental toxicants in humans, we propose to apply evolutionary genetics to improve the experimental design and data interpretation with various in vitro and whole-organism models. We review five molecular systems of stress response and update 18 consensual cell-cell signaling pathways that are the hallmark for early development, organogenesis, and differentiation; and revisit the principles of teratology in light of recent advances in high-throughput screening, big data techniques, and systems toxicology. Multiscale systems modeling plays an integral role in the evolutionary approach to cross-species extrapolation. Phylogenetic analysis and comparative bioinformatics are both valuable tools in identifying and validating the molecular initiating events that account for adverse developmental outcomes in humans. The discordance of susceptibility between test species and humans (ontogeny) reflects their differences in evolutionary history (phylogeny). This synthesis not only can lead to novel applications in developmental toxicity and risk assessment, but also can pave the way for applying an evo-devo perspective to the study of developmental origins of health and disease.
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Affiliation(s)
- Maxwell C K Leung
- Nicholas School of the Environment, Duke University, Durham, NC, United States.
| | - Andrew C Procter
- Institute for Advanced Analytics, North Carolina State University, Raleigh, NC, United States
| | - Jared V Goldstone
- Department of Biology, Woods Hole Oceanographic Institution, Woods Hole, MA, United States
| | - Jonathan Foox
- Department of Invertebrate Zoology, American Museum of Natural History, New York, New York, United States
| | - Robert DeSalle
- Department of Invertebrate Zoology, American Museum of Natural History, New York, New York, United States
| | - Carolyn J Mattingly
- Department of Biological Sciences, North Carolina State University, Raleigh, North Carolina, United States
| | - Mark E Siddall
- Department of Invertebrate Zoology, American Museum of Natural History, New York, New York, United States
| | - Alicia R Timme-Laragy
- Department of Environmental Health Sciences, University of Massachusetts, Amherst, MA, United States
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14
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Carter JA, Hyland C, Steele RE, Collins EMS. Dynamics of Mouth Opening in Hydra. Biophys J 2016; 110:1191-201. [PMID: 26958895 DOI: 10.1016/j.bpj.2016.01.008] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2015] [Revised: 12/18/2015] [Accepted: 01/05/2016] [Indexed: 11/20/2022] Open
Abstract
Hydra, a simple freshwater animal famous for its regenerative capabilities, must tear a hole through its epithelial tissue each time it opens its mouth. The feeding response of Hydra has been well-characterized physiologically and is regarded as a classical model system for environmental chemical biology. However, due to a lack of in vivo labeling and imaging tools, the biomechanics of mouth opening have remained completely unexplored. We take advantage of the availability of transgenic Hydra lines to perform the first dynamical analysis, to our knowledge, of Hydra mouth opening and test existing hypotheses regarding the underlying cellular mechanisms. Through cell position and shape tracking, we show that mouth opening is accompanied by changes in cell shape, but not cellular rearrangements as previously suggested. Treatment with a muscle relaxant impairs mouth opening, supporting the hypothesis that mouth opening is an active process driven by radial contractile processes (myonemes) in the ectoderm. Furthermore, we find that all events exhibit the same relative rate of opening. Because one individual can open consecutively to different amounts, this suggests that the degree of mouth opening is controlled through neuronal signaling. Finally, from the opening dynamics and independent measurements of the elastic properties of the tissues, we estimate the forces exerted by the myonemes to be on the order of a few nanoNewtons. Our study provides the first dynamical framework, to our knowledge, for understanding the remarkable plasticity of the Hydra mouth and illustrates that Hydra is a powerful system for quantitative biomechanical studies of cell and tissue behaviors in vivo.
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Affiliation(s)
- Jason A Carter
- Division of Biological Sciences, University of California San Diego, La Jolla, California
| | - Callen Hyland
- Division of Biological Sciences, University of California San Diego, La Jolla, California
| | - Robert E Steele
- Department of Biological Chemistry and Developmental Biology Center, University of California Irvine, Irvine, California
| | - Eva-Maria S Collins
- Division of Biological Sciences, University of California San Diego, La Jolla, California; Department of Physics, University of California San Diego, La Jolla, California.
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15
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Sequential development of apical-basal and planar polarities in aggregating epitheliomuscular cells of Hydra. Dev Biol 2016; 412:148-159. [DOI: 10.1016/j.ydbio.2016.02.022] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2015] [Revised: 02/18/2016] [Accepted: 02/23/2016] [Indexed: 11/24/2022]
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16
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Insight into the molecular and functional diversity of cnidarian neuropeptides. Int J Mol Sci 2015; 16:2610-25. [PMID: 25625515 PMCID: PMC4346854 DOI: 10.3390/ijms16022610] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2014] [Revised: 01/06/2015] [Accepted: 01/15/2015] [Indexed: 12/18/2022] Open
Abstract
Cnidarians are the most primitive animals to possess a nervous system. This phylum is composed of the classes Scyphozoa (jellyfish), Cubozoa (box jellyfish), and Hydrozoa (e.g., Hydra, Hydractinia), which make up the subphylum Medusozoa, as well as the class Anthozoa (sea anemones and corals). Neuropeptides have an early evolutionary origin and are already abundant in cnidarians. For example, from the cnidarian Hydra, a key model system for studying the peptides involved in developmental and physiological processes, we identified a wide variety of novel neuropeptides from Hydra magnipapillata (the Hydra Peptide Project). Most of these peptides act directly on muscle cells and induce contraction and relaxation. Some peptides are involved in cell differentiation and morphogenesis. In this review, we describe FMRFamide-like peptides (FLPs), GLWamide-family peptides, and the neuropeptide Hym-355; FPQSFLPRGamide. Several hundred FLPs have been isolated from invertebrate animals such as cnidarians. GLWamide-family peptides function as signaling molecules in muscle contraction, metamorphosis, and settlement in cnidarians. Hym-355; FPQSFLPRGamide enhances neuronal differentiation in Hydra. Recently, GLWamide-family peptides and Hym-355; FPQSFLPRGamide were shown to trigger oocyte maturation and subsequent spawning in the hydrozoan jellyfish Cytaeis uchidae. These findings suggest the importance of these neuropeptides in both developmental and physiological processes.
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17
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Juliano CE, Lin H, Steele RE. Generation of transgenic Hydra by embryo microinjection. J Vis Exp 2014:51888. [PMID: 25285460 DOI: 10.3791/51888] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
As a member of the phylum Cnidaria, the sister group to all bilaterians, Hydra can shed light on fundamental biological processes shared among multicellular animals. Hydra is used as a model for the study of regeneration, pattern formation, and stem cells. However, research efforts have been hampered by lack of a reliable method for gene perturbations to study molecular function. The development of transgenic methods has revitalized the study of Hydra biology(1). Transgenic Hydra allow for the tracking of live cells, sorting to yield pure cell populations for biochemical analysis, manipulation of gene function by knockdown and over-expression, and analysis of promoter function. Plasmid DNA injected into early stage embryos randomly integrates into the genome early in development. This results in hatchlings that express transgenes in patches of tissue in one or more of the three lineages (ectodermal epithelial, endodermal epithelial, or interstitial). The success rate of obtaining a hatchling with transgenic tissue is between 10% and 20%. Asexual propagation of the transgenic hatchling is used to establish a uniformly transgenic line in a particular lineage. Generating transgenic Hydra is surprisingly simple and robust, and here we describe a protocol that can be easily implemented at low cost.
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Affiliation(s)
- Celina E Juliano
- Yale Stem Cell Center and Department of Cell Biology, Yale University School of Medicine;
| | - Haifan Lin
- Yale Stem Cell Center and Department of Cell Biology, Yale University School of Medicine
| | - Robert E Steele
- Department of Biological Chemistry and the Developmental Biology Center, University of California, Irvine;
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18
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Nodal signalling determines biradial asymmetry in Hydra. Nature 2014; 515:112-5. [PMID: 25156256 DOI: 10.1038/nature13666] [Citation(s) in RCA: 73] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2013] [Accepted: 07/07/2014] [Indexed: 11/09/2022]
Abstract
In bilaterians, three orthogonal body axes define the animal form, with distinct anterior-posterior, dorsal-ventral and left-right asymmetries. The key signalling factors are Wnt family proteins for the anterior-posterior axis, Bmp family proteins for the dorsal-ventral axis and Nodal for the left-right axis. Cnidarians, the sister group to bilaterians, are characterized by one oral-aboral body axis, which exhibits a distinct biradiality of unknown molecular nature. Here we analysed the biradial growth pattern in the radially symmetrical cnidarian polyp Hydra, and we report evidence of Nodal in a pre-bilaterian clade. We identified a Nodal-related gene (Ndr) in Hydra magnipapillata, and this gene is essential for setting up an axial asymmetry along the main body axis. This asymmetry defines a lateral signalling centre, inducing a new body axis of a budding polyp orthogonal to the mother polyp's axis. Ndr is expressed exclusively in the lateral bud anlage and induces Pitx, which encodes an evolutionarily conserved transcription factor that functions downstream of Nodal. Reminiscent of its function in vertebrates, Nodal acts downstream of β-Catenin signalling. Our data support an evolutionary scenario in which a 'core-signalling cassette' consisting of β-Catenin, Nodal and Pitx pre-dated the cnidarian-bilaterian split. We presume that this cassette was co-opted for various modes of axial patterning: for example, for lateral branching in cnidarians and left-right patterning in bilaterians.
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PIWI proteins and PIWI-interacting RNAs function in Hydra somatic stem cells. Proc Natl Acad Sci U S A 2013; 111:337-42. [PMID: 24367095 DOI: 10.1073/pnas.1320965111] [Citation(s) in RCA: 109] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
PIWI proteins and their bound PIWI-interacting RNAs (piRNAs) are found in animal germlines and are essential for fertility, but their functions outside of the gonad are not well understood. The cnidarian Hydra is a simple metazoan with well-characterized stem/progenitor cells that provides a unique model for analysis of PIWI function. Here we report that Hydra has two PIWI proteins, Hydra PIWI (Hywi) and Hydra PIWI-like (Hyli), both of which are expressed in all Hydra stem/progenitor cells, but not in terminally differentiated cells. We identified ∼15 million piRNAs associated with Hywi and/or Hyli and found that they exhibit the ping-pong signature of piRNA biogenesis. Hydra PIWI proteins are strictly cytoplasmic and thus likely act as posttranscriptional regulators. To explore this function, we generated a Hydra transcriptome for piRNA mapping. piRNAs map to transposons with a 25- to 35-fold enrichment compared with the abundance of transposon transcripts. By sequencing the small RNAs specific to the interstitial, ectodermal, and endodermal lineages, we found that the targeting of transposons appears to be largely restricted to the interstitial lineage. We also identified putative nontransposon targets of the pathway unique to each lineage. Finally we demonstrate that hywi function is essential in the somatic epithelial lineages. This comprehensive analysis of the PIWI-piRNA pathway in the somatic stem/progenitor cells of a nonbilaterian animal suggests that this pathway originated with broader stem cell functionality.
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