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Manni L, Anselmi C. Giovanna Zaniolo: An inspiring scientist, teacher, mentor, and colleague. Active: 1967-2012. Genesis 2023; 61:e23566. [PMID: 37920942 DOI: 10.1002/dvg.23566] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2023] [Revised: 10/04/2023] [Accepted: 10/06/2023] [Indexed: 11/04/2023]
Affiliation(s)
- Lucia Manni
- Dipartimento di Biologia, Università Degli Studi di Padova, Padova, Italy
| | - Chiara Anselmi
- Hopkins Marine Station, Institute for Stem Cell Biology and Regenerative Medicine, Stanford University, Pacific Grove, California, USA
- Institute for Stem Cell Biology and Regenerative Medicine, Stanford University School of Medicine, Stanford, California, USA
- Wu Tsai Neurosciences Institute, Stanford University, Stanford, California, USA
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Anselmi C, Caicci F, Bocci T, Guidetti M, Priori A, Giusti V, Levy T, Raveh T, Voskoboynik A, Weissman IL, Manni L. Multiple Forms of Neural Cell Death in the Cyclical Brain Degeneration of A Colonial Chordate. Cells 2023; 12:1041. [PMID: 37048113 PMCID: PMC10093557 DOI: 10.3390/cells12071041] [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: 02/24/2023] [Revised: 03/20/2023] [Accepted: 03/24/2023] [Indexed: 03/31/2023] Open
Abstract
Human neuronal loss occurs through different cellular mechanisms, mainly studied in vitro. Here, we characterized neuronal death in B. schlosseri, a marine colonial tunicate that shares substantial genomic homology with mammals and has a life history in which controlled neurodegeneration happens simultaneously in the brains of adult zooids during a cyclical phase named takeover. Using an ultrastructural and transcriptomic approach, we described neuronal death forms in adult zooids before and during the takeover phase while comparing adult zooids in takeover with their buds where brains are refining their structure. At takeover, we found in neurons clear morphologic signs of apoptosis (i.e., chromatin condensation, lobed nuclei), necrosis (swollen cytoplasm) and autophagy (autophagosomes, autolysosomes and degradative multilamellar bodies). These results were confirmed by transcriptomic analyses that highlighted the specific genes involved in these cell death pathways. Moreover, the presence of tubulovesicular structures in the brain medulla alongside the over-expression of prion disease genes in late cycle suggested a cell-to-cell, prion-like propagation recalling the conformational disorders typical of some human neurodegenerative diseases. We suggest that improved understanding of how neuronal alterations are regulated in the repeated degeneration-regeneration program of B. schlosseri may yield mechanistic insights relevant to the study of human neurodegenerative diseases.
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Affiliation(s)
- Chiara Anselmi
- Hopkins Marine Station, Institute for Stem Cell Biology and Regenerative Medicine, Stanford University, Pacific Grove, CA 93950, USA
- Institute for Stem Cell Biology and Regenerative Medicine, Stanford University School of Medicine, Stanford, CA 94305, USA
- Wu Tsai Neurosciences Institute, Stanford University, Stanford, CA 94305, USA
| | - Federico Caicci
- Dipartimento di Biologia, Università degli Studi di Padova, 35131 Padova, Italy
| | - Tommaso Bocci
- “Aldo Ravelli” Center for Neurotechnology and Experimental Brain Therapeutics, Department of Health Sciences, University of Milan, 20142 Milan, Italy
| | - Matteo Guidetti
- “Aldo Ravelli” Center for Neurotechnology and Experimental Brain Therapeutics, Department of Health Sciences, University of Milan, 20142 Milan, Italy
- Department of Electronics, Information and Bioengineering, Politecnico di Milano, 20133 Milan, Italy
| | - Alberto Priori
- “Aldo Ravelli” Center for Neurotechnology and Experimental Brain Therapeutics, Department of Health Sciences, University of Milan, 20142 Milan, Italy
| | | | - Tom Levy
- Hopkins Marine Station, Institute for Stem Cell Biology and Regenerative Medicine, Stanford University, Pacific Grove, CA 93950, USA
- Institute for Stem Cell Biology and Regenerative Medicine, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Tal Raveh
- Institute for Stem Cell Biology and Regenerative Medicine, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Ayelet Voskoboynik
- Hopkins Marine Station, Institute for Stem Cell Biology and Regenerative Medicine, Stanford University, Pacific Grove, CA 93950, USA
- Institute for Stem Cell Biology and Regenerative Medicine, Stanford University School of Medicine, Stanford, CA 94305, USA
- Chan Zuckerberg Biohub, San Francisco, CA 94158, USA
| | - Irving L. Weissman
- Institute for Stem Cell Biology and Regenerative Medicine, Stanford University School of Medicine, Stanford, CA 94305, USA
- Department of Pathology, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Lucia Manni
- Wu Tsai Neurosciences Institute, Stanford University, Stanford, CA 94305, USA
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3
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Thompson SH, Anselmi C, Ishizuka KJ, Palmeri KJ, Voskoboynik A. Contributions from both the brain and the vascular network guide behavior in the colonial tunicate Botryllus schlosseri. J Exp Biol 2022; 225:279340. [PMID: 36314197 PMCID: PMC9720745 DOI: 10.1242/jeb.244491] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2022] [Accepted: 10/19/2022] [Indexed: 11/07/2022]
Abstract
We studied the function, development and aging of the adult nervous system in the colonial tunicate Botryllus schlosseri. Adults, termed zooids, are filter-feeding individuals. Sister zooids group together to form modules, and modules, in turn, are linked by a shared vascular network to form a well-integrated colony. Zooids undergo a weekly cycle of regression and renewal during which mature zooids are replaced by developing buds. The zooid brain matures and degenerates on this 7-day cycle. We used focal extracellular recording and video imaging to explore brain activity in the context of development and degeneration and to examine the contributions of the nervous system and vascular network to behavior. Recordings from the brain revealed complex firing patterns arising both spontaneously and in response to stimulation. Neural activity increases as the brain matures and declines thereafter. Motor behavior follows the identical time course. The behavior of each zooid is guided predominantly by its individual brain, but sister zooids can also exhibit synchronous motor behavior. The vascular network also generates action potentials that are largely independent of neural activity. In addition, the entire vascular network undergoes slow rhythmic contractions that appear to arise from processes endogenous to vascular epithelial cells. We found that neurons in the brain and cells of the vascular network both express multiple genes for voltage-gated Na+ and Ca2+ ion channels homologous (based on sequence) to mammalian ion channel genes.
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Affiliation(s)
- Stuart H. Thompson
- Department of Biology and Hopkins Marine Station, Stanford University, Stanford, CA 93950, USA,Author for correspondence ()
| | - Chiara Anselmi
- Department of Biology and Hopkins Marine Station, Stanford University, Stanford, CA 93950, USA,Institute for Stem Cell Biology and Regenerative Medicine, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Katherine J. Ishizuka
- Department of Biology and Hopkins Marine Station, Stanford University, Stanford, CA 93950, USA,Institute for Stem Cell Biology and Regenerative Medicine, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Karla J. Palmeri
- Department of Biology and Hopkins Marine Station, Stanford University, Stanford, CA 93950, USA,Institute for Stem Cell Biology and Regenerative Medicine, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Ayelet Voskoboynik
- Department of Biology and Hopkins Marine Station, Stanford University, Stanford, CA 93950, USA,Institute for Stem Cell Biology and Regenerative Medicine, Stanford University School of Medicine, Stanford, CA 94305, USA,Chan Zuckerberg Biohub, San Francisco, CA 94158, USA
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4
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Anselmi C, Kowarsky M, Gasparini F, Caicci F, Ishizuka KJ, Palmeri KJ, Raveh T, Sinha R, Neff N, Quake SR, Weissman IL, Voskoboynik A, Manni L. Two distinct evolutionary conserved neural degeneration pathways characterized in a colonial chordate. Proc Natl Acad Sci U S A 2022; 119:e2203032119. [PMID: 35858312 PMCID: PMC9303981 DOI: 10.1073/pnas.2203032119] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2022] [Accepted: 04/21/2022] [Indexed: 12/13/2022] Open
Abstract
Colonial tunicates are marine organisms that possess multiple brains simultaneously during their colonial phase. While the cyclical processes of neurogenesis and neurodegeneration characterizing their life cycle have been documented previously, the cellular and molecular changes associated with such processes and their relationship with variation in brain morphology and individual (zooid) behavior throughout adult life remains unknown. Here, we introduce Botryllus schlosseri as an invertebrate model for neurogenesis, neural degeneration, and evolutionary neuroscience. Our analysis reveals that during the weekly colony budding (i.e., asexual reproduction), prior to programmed cell death and removal by phagocytes, decreases in the number of neurons in the adult brain are associated with reduced behavioral response and significant change in the expression of 73 mammalian homologous genes associated with neurodegenerative disease. Similarly, when comparing young colonies (1 to 2 y of age) to those reared in a laboratory for ∼20 y, we found that older colonies contained significantly fewer neurons and exhibited reduced behavioral response alongside changes in the expression of 148 such genes (35 of which were differentially expressed across both timescales). The existence of two distinct yet apparently related neurodegenerative pathways represents a novel platform to study the gene products governing the relationship between aging, neural regeneration and degeneration, and loss of nervous system function. Indeed, as a member of an evolutionary clade considered to be a sister group of vertebrates, this organism may be a fundamental resource in understanding how evolution has shaped these processes across phylogeny and obtaining mechanistic insight.
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Affiliation(s)
- Chiara Anselmi
- Stanford University, Hopkins Marine Station, Pacific Grove, CA 93950
- Institute for Stem Cell Biology and Regenerative Medicine, Stanford University School of Medicine, Stanford, CA 94305
| | - Mark Kowarsky
- Department of Physics, Stanford University, Stanford, CA 94305
| | - Fabio Gasparini
- Dipartimento di Biologia, Università degli Studi di Padova, 35131, Padova, Italy
| | - Federico Caicci
- Dipartimento di Biologia, Università degli Studi di Padova, 35131, Padova, Italy
| | | | - Karla J. Palmeri
- Stanford University, Hopkins Marine Station, Pacific Grove, CA 93950
| | - Tal Raveh
- Institute for Stem Cell Biology and Regenerative Medicine, Stanford University School of Medicine, Stanford, CA 94305
| | - Rahul Sinha
- Institute for Stem Cell Biology and Regenerative Medicine, Stanford University School of Medicine, Stanford, CA 94305
| | - Norma Neff
- Chan Zuckerberg Biohub, San Francisco CA 94158
| | - Stephen R. Quake
- Chan Zuckerberg Biohub, San Francisco CA 94158
- Departments of Applied Physics and Bioengineering, Stanford University, Stanford, CA 94305
| | - Irving L. Weissman
- Institute for Stem Cell Biology and Regenerative Medicine, Stanford University School of Medicine, Stanford, CA 94305
- Chan Zuckerberg Biohub, San Francisco CA 94158
- Department of Biology, Stanford University, Hopkins Marine Station, Pacific Grove, CA 93950
| | - Ayelet Voskoboynik
- Stanford University, Hopkins Marine Station, Pacific Grove, CA 93950
- Institute for Stem Cell Biology and Regenerative Medicine, Stanford University School of Medicine, Stanford, CA 94305
- Chan Zuckerberg Biohub, San Francisco CA 94158
- Department of Biology, Stanford University, Hopkins Marine Station, Pacific Grove, CA 93950
| | - Lucia Manni
- Dipartimento di Biologia, Università degli Studi di Padova, 35131, Padova, Italy
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5
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Kraus A, Buckley KM, Salinas I. Sensing the world and its dangers: An evolutionary perspective in neuroimmunology. eLife 2021; 10:66706. [PMID: 33900197 PMCID: PMC8075586 DOI: 10.7554/elife.66706] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2021] [Accepted: 04/09/2021] [Indexed: 12/14/2022] Open
Abstract
Detecting danger is key to the survival and success of all species. Animal nervous and immune systems cooperate to optimize danger detection. Preceding studies have highlighted the benefits of bringing neurons into the defense game, including regulation of immune responses, wound healing, pathogen control, and survival. Here, we summarize the body of knowledge in neuroimmune communication and assert that neuronal participation in the immune response is deeply beneficial in each step of combating infection, from inception to resolution. Despite the documented tight association between the immune and nervous systems in mammals or invertebrate model organisms, interdependence of these two systems is largely unexplored across metazoans. This review brings a phylogenetic perspective of the nervous and immune systems in the context of danger detection and advocates for the use of non-model organisms to diversify the field of neuroimmunology. We identify key taxa that are ripe for investigation due to the emergence of key evolutionary innovations in their immune and nervous systems. This novel perspective will help define the primordial principles that govern neuroimmune communication across taxa.
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Affiliation(s)
- Aurora Kraus
- Department of Biology, University of New Mexico, Albuquerque, United States
| | | | - Irene Salinas
- Department of Biology, University of New Mexico, Albuquerque, United States
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Kowarsky M, Anselmi C, Hotta K, Burighel P, Zaniolo G, Caicci F, Rosental B, Neff NF, Ishizuka KJ, Palmeri KJ, Okamoto J, Gordon T, Weissman IL, Quake SR, Manni L, Voskoboynik A. Sexual and asexual development: two distinct programs producing the same tunicate. Cell Rep 2021; 34:108681. [PMID: 33503429 PMCID: PMC7949349 DOI: 10.1016/j.celrep.2020.108681] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2019] [Revised: 08/24/2020] [Accepted: 12/30/2020] [Indexed: 01/04/2023] Open
Abstract
Colonial tunicates are the only chordate that possess two distinct developmental pathways to produce an adult body: either sexually through embryogenesis or asexually through a stem cell-mediated renewal termed blastogenesis. Using the colonial tunicate Botryllus schlosseri, we combine transcriptomics and microscopy to build an atlas of the molecular and morphological signatures at each developmental stage for both pathways. The general molecular profiles of these processes are largely distinct. However, the relative timing of organogenesis and ordering of tissue-specific gene expression are conserved. By comparing the developmental pathways of B. schlosseri with other chordates, we identify hundreds of putative transcription factors with conserved temporal expression. Our findings demonstrate that convergent morphology need not imply convergent molecular mechanisms but that it showcases the importance that tissue-specific stem cells and transcription factors play in producing the same mature body through different pathways.
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Affiliation(s)
- Mark Kowarsky
- Department of Physics, Stanford University, Stanford, CA 94305, USA
| | - Chiara Anselmi
- Dipartimento di Biologia, Università degli Studi di Padova, 35122 Padova, Italy; Institute for Stem Cell Biology and Regenerative Medicine, and Ludwig Center, Stanford University School of Medicine, Stanford, CA 94305, USA; Department of Biology, Stanford University, Hopkins Marine Station, Pacific Grove, CA 93950, USA
| | - Kohji Hotta
- Department of Biosciences and Informatics, Keio University, Yokohama 223-8522, Japan
| | - Paolo Burighel
- Dipartimento di Biologia, Università degli Studi di Padova, 35122 Padova, Italy
| | - Giovanna Zaniolo
- Dipartimento di Biologia, Università degli Studi di Padova, 35122 Padova, Italy
| | - Federico Caicci
- Dipartimento di Biologia, Università degli Studi di Padova, 35122 Padova, Italy
| | - Benyamin Rosental
- Institute for Stem Cell Biology and Regenerative Medicine, and Ludwig Center, Stanford University School of Medicine, Stanford, CA 94305, USA; Department of Biology, Stanford University, Hopkins Marine Station, Pacific Grove, CA 93950, USA; The Shraga Segal Department of Microbiology, Immunology and Genetics, Faculty of Health Sciences, Center for Regenerative Medicine and Stem Cells, Ben-Gurion University of the Negev, Beer-Sheva 84105, Israel
| | - Norma F Neff
- Chan Zuckerberg Biohub, San Francisco, CA 94158, USA
| | - Katherine J Ishizuka
- Institute for Stem Cell Biology and Regenerative Medicine, and Ludwig Center, Stanford University School of Medicine, Stanford, CA 94305, USA; Department of Biology, Stanford University, Hopkins Marine Station, Pacific Grove, CA 93950, USA
| | - Karla J Palmeri
- Institute for Stem Cell Biology and Regenerative Medicine, and Ludwig Center, Stanford University School of Medicine, Stanford, CA 94305, USA; Department of Biology, Stanford University, Hopkins Marine Station, Pacific Grove, CA 93950, USA
| | | | - Tal Gordon
- Zoology Department, Tel Aviv University, Tel Aviv 69978, Israel
| | - Irving L Weissman
- Institute for Stem Cell Biology and Regenerative Medicine, and Ludwig Center, Stanford University School of Medicine, Stanford, CA 94305, USA; Department of Biology, Stanford University, Hopkins Marine Station, Pacific Grove, CA 93950, USA; Chan Zuckerberg Biohub, San Francisco, CA 94158, USA
| | - Stephen R Quake
- Chan Zuckerberg Biohub, San Francisco, CA 94158, USA; Departments of Applied Physics and Bioengineering, Stanford University, Stanford, CA 94305, USA
| | - Lucia Manni
- Dipartimento di Biologia, Università degli Studi di Padova, 35122 Padova, Italy.
| | - Ayelet Voskoboynik
- Institute for Stem Cell Biology and Regenerative Medicine, and Ludwig Center, Stanford University School of Medicine, Stanford, CA 94305, USA; Department of Biology, Stanford University, Hopkins Marine Station, Pacific Grove, CA 93950, USA; Chan Zuckerberg Biohub, San Francisco, CA 94158, USA.
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7
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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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Manni L, Anselmi C, Burighel P, Martini M, Gasparini F. Differentiation and Induced Sensorial Alteration of the Coronal Organ in the Asexual Life of a Tunicate. Integr Comp Biol 2019; 58:317-328. [PMID: 29873734 DOI: 10.1093/icb/icy044] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Tunicates, the sister group of vertebrates, possess a mechanoreceptor organ, the coronal organ, which is considered the best candidate to address the controversial issue of vertebrate hair cell evolution. The organ, located at the base of the oral siphon, controls the flow of seawater into the organism and can drive the "squirting" reaction, i.e., the rapid body muscle contraction used to eject dangerous particles during filtration. Coronal sensory cells are secondary mechanoreceptors and share morphological, developmental, and molecular traits with vertebrate hair cells. In the colonial tunicate Botryllus schlosseri, we described coronal organ differentiation during asexual development. Moreover, we showed that the ototoxic aminoglycoside gentamicin caused morphological and mechanosensorial impairment in coronal cells. Finally, fenofibrate had a strong protective effect on coronal sensory cells due to gentamicin-induced toxicity, as occurs in vertebrate hair cells. Our results reinforce the hypothesis of homology between vertebrate hair cells and tunicate coronal sensory cells.
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Affiliation(s)
- Lucia Manni
- Dipartimento di Biologia, Università degli Studi di Padova, Via U. Bassi 58/B, 35121 Padova, Italy
| | - Chiara Anselmi
- Dipartimento di Biologia, Università degli Studi di Padova, Via U. Bassi 58/B, 35121 Padova, Italy
| | - Paolo Burighel
- Dipartimento di Biologia, Università degli Studi di Padova, Via U. Bassi 58/B, 35121 Padova, Italy
| | - Margherita Martini
- Dipartimento di Biologia, Università degli Studi di Padova, Via U. Bassi 58/B, 35121 Padova, Italy
| | - Fabio Gasparini
- Dipartimento di Biologia, Università degli Studi di Padova, Via U. Bassi 58/B, 35121 Padova, Italy
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9
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Rosental B, Kowarsky M, Seita J, Corey DM, Ishizuka KJ, Palmeri KJ, Chen SY, Sinha R, Okamoto J, Mantalas G, Manni L, Raveh T, Clarke DN, Tsai JM, Newman AM, Neff NF, Nolan GP, Quake SR, Weissman IL, Voskoboynik A. Complex mammalian-like haematopoietic system found in a colonial chordate. Nature 2018; 564:425-429. [PMID: 30518860 PMCID: PMC6347970 DOI: 10.1038/s41586-018-0783-x] [Citation(s) in RCA: 45] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2017] [Accepted: 10/15/2018] [Indexed: 12/11/2022]
Abstract
Haematopoiesis is an essential process that evolved in multicellular animals. At the heart of this process are haematopoietic stem cells (HSCs), which are multipotent and self-renewing, and generate the entire repertoire of blood and immune cells throughout an animal's life1. Although there have been comprehensive studies on self-renewal, differentiation, physiological regulation and niche occupation in vertebrate HSCs, relatively little is known about the evolutionary origin and niches of these cells. Here we describe the haematopoietic system of Botryllus schlosseri, a colonial tunicate that has a vasculature and circulating blood cells, and interesting stem-cell biology and immunity characteristics2-8. Self-recognition between genetically compatible B. schlosseri colonies leads to the formation of natural parabionts with shared circulation, whereas incompatible colonies reject each other3,4,7. Using flow cytometry, whole-transcriptome sequencing of defined cell populations and diverse functional assays, we identify HSCs, progenitors, immune effector cells and an HSC niche, and demonstrate that self-recognition inhibits allospecific cytotoxic reactions. Our results show that HSC and myeloid lineage immune cells emerged in a common ancestor of tunicates and vertebrates, and also suggest that haematopoietic bone marrow and the B. schlosseri endostyle niche evolved from a common origin.
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Affiliation(s)
- Benyamin Rosental
- Institute for Stem Cell Biology and Regenerative Medicine, Stanford University School of Medicine, Stanford, CA, USA.
- Department of Biology, Stanford University, Hopkins Marine Station, Pacific Grove, CA, USA.
| | - Mark Kowarsky
- Department of Physics, Stanford University, Stanford, CA, USA
| | - Jun Seita
- Institute for Stem Cell Biology and Regenerative Medicine, Stanford University School of Medicine, Stanford, CA, USA
- AI based Healthcare and Medical Data Analysis Standardization Unit, Medical Sciences Innovation Hub Program, RIKEN, Tokyo, Japan
| | - Daniel M Corey
- Institute for Stem Cell Biology and Regenerative Medicine, Stanford University School of Medicine, Stanford, CA, USA
| | - Katherine J Ishizuka
- Institute for Stem Cell Biology and Regenerative Medicine, Stanford University School of Medicine, Stanford, CA, USA
- Department of Biology, Stanford University, Hopkins Marine Station, Pacific Grove, CA, USA
| | - Karla J Palmeri
- Institute for Stem Cell Biology and Regenerative Medicine, Stanford University School of Medicine, Stanford, CA, USA
- Department of Biology, Stanford University, Hopkins Marine Station, Pacific Grove, CA, USA
| | - Shih-Yu Chen
- Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, CA, USA
| | - Rahul Sinha
- Institute for Stem Cell Biology and Regenerative Medicine, Stanford University School of Medicine, Stanford, CA, USA
| | | | - Gary Mantalas
- Department of Bioengineering, Stanford University, Stanford, CA, USA
- Department of Molecular Cellular and Developmental Biology, University of California Santa Cruz, Santa Cruz, CA, USA
| | - Lucia Manni
- Dipartimento di Biologia, Università degli Studi di Padova, Padova, Italy
| | - Tal Raveh
- Institute for Stem Cell Biology and Regenerative Medicine, Stanford University School of Medicine, Stanford, CA, USA
| | - D Nathaniel Clarke
- Department of Biology, Stanford University, Hopkins Marine Station, Pacific Grove, CA, USA
| | - Jonathan M Tsai
- Institute for Stem Cell Biology and Regenerative Medicine, Stanford University School of Medicine, Stanford, CA, USA
| | - Aaron M Newman
- Institute for Stem Cell Biology and Regenerative Medicine, Stanford University School of Medicine, Stanford, CA, USA
| | | | - Garry P Nolan
- Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, CA, USA
| | - Stephen R Quake
- Chan Zuckerberg Biohub, San Francisco, CA, USA
- Department of Bioengineering, Stanford University, Stanford, CA, USA
| | - Irving L Weissman
- Institute for Stem Cell Biology and Regenerative Medicine, Stanford University School of Medicine, Stanford, CA, USA.
- Department of Biology, Stanford University, Hopkins Marine Station, Pacific Grove, CA, USA.
- Ludwig Center for Cancer Stem Cell Research and Medicine, Stanford University School of Medicine, Stanford, CA, USA.
| | - Ayelet Voskoboynik
- Institute for Stem Cell Biology and Regenerative Medicine, Stanford University School of Medicine, Stanford, CA, USA.
- Department of Biology, Stanford University, Hopkins Marine Station, Pacific Grove, CA, USA.
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10
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Braun K, Stach T. Morphology and evolution of the central nervous system in adult tunicates. J ZOOL SYST EVOL RES 2018. [DOI: 10.1111/jzs.12246] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Katrin Braun
- Institut für Biologie, Vergleichende Zoologie Humboldt‐Universität zu Berlin Berlin Germany
| | - Thomas Stach
- Institut für Biologie, Molekulare Parasitologie Humboldt‐Universität zu Berlin Berlin Germany
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11
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Nishino A. Morphology and Physiology of the Ascidian Nervous Systems and the Effectors. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2018. [PMID: 29542090 DOI: 10.1007/978-981-10-7545-2_16] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Neurobiology in ascidians has made many advances. Ascidians have offered natural advantages to researchers, including fecundity, structural simplicity, invariant morphology, and fast and stereotyped developmental processes. The researchers have also accumulated on this animal a great deal of knowledge, genomic resources, and modern genetic techniques. A recent connectomic analysis has shown an ultimately resolved image of the larval nervous system, whereas recent applications of live imaging and optogenetics have clarified the functional organization of the juvenile nervous system. Progress in resources and techniques have provided convincing ways to deepen what we have wanted to know about the nervous systems of ascidians. Here, the research history and the current views regarding ascidian nervous systems are summarized.
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Affiliation(s)
- Atsuo Nishino
- Department of Biology, Faculty of Agriculture and Life Science, Hirosaki University, Hirosaki, Aomori, Japan.
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12
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Manni L, Gasparini F, Hotta K, Ishizuka KJ, Ricci L, Tiozzo S, Voskoboynik A, Dauga D. Ontology for the asexual development and anatomy of the colonial chordate Botryllus schlosseri. PLoS One 2014; 9:e96434. [PMID: 24789338 PMCID: PMC4006837 DOI: 10.1371/journal.pone.0096434] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2014] [Accepted: 04/07/2014] [Indexed: 12/13/2022] Open
Abstract
Ontologies provide an important resource to integrate information. For developmental biology and comparative anatomy studies, ontologies of a species are used to formalize and annotate data that are related to anatomical structures, their lineage and timing of development. Here, we have constructed the first ontology for anatomy and asexual development (blastogenesis) of a bilaterian, the colonial tunicate Botryllus schlosseri. Tunicates, like Botryllus schlosseri, are non-vertebrates and the only chordate taxon species that reproduce both sexually and asexually. Their tadpole larval stage possesses structures characteristic of all chordates, i.e. a notochord, a dorsal neural tube, and gill slits. Larvae settle and metamorphose into individuals that are either solitary or colonial. The latter reproduce both sexually and asexually and these two reproductive modes lead to essentially the same adult body plan. The Botryllus schlosseri Ontology of Development and Anatomy (BODA) will facilitate the comparison between both types of development. BODA uses the rules defined by the Open Biomedical Ontologies Foundry. It is based on studies that investigate the anatomy, blastogenesis and regeneration of this organism. BODA features allow the users to easily search and identify anatomical structures in the colony, to define the developmental stage, and to follow the morphogenetic events of a tissue and/or organ of interest throughout asexual development. We invite the scientific community to use this resource as a reference for the anatomy and developmental ontology of B. schlosseri and encourage recommendations for updates and improvements.
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Affiliation(s)
- Lucia Manni
- Department of Biology, University of Padova, Padova, Italy
| | | | - Kohji Hotta
- Department of Biosciences and Informatics, Faculty of Science and Technology, Keio University, Kouhoku-ku, Yokohama, Japan
| | - Katherine J. Ishizuka
- Institute for Stem Cell Biology and Regenerative Medicine, and Hopkins Marine Station, Stanford, California, United States of America
| | - Lorenzo Ricci
- Centre National de la Recherche Scientifique, Sorbonne Universités, Université Pierre et Marie Curie (University of Paris 06), Laboratoire de Biologie du Développement de Villefranche-sur-mer, Observatoire Océanographique, Villefranche-sur-mer, France
| | - Stefano Tiozzo
- Centre National de la Recherche Scientifique, Sorbonne Universités, Université Pierre et Marie Curie (University of Paris 06), Laboratoire de Biologie du Développement de Villefranche-sur-mer, Observatoire Océanographique, Villefranche-sur-mer, France
| | - Ayelet Voskoboynik
- Institute for Stem Cell Biology and Regenerative Medicine, and Hopkins Marine Station, Stanford, California, United States of America
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13
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Gasparini F, Caicci F, Rigon F, Zaniolo G, Burighel P, Manni L. Cytodifferentiation of hair cells during the development of a basal chordate. Hear Res 2013; 304:188-99. [PMID: 23876523 DOI: 10.1016/j.heares.2013.07.006] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/21/2012] [Revised: 05/28/2013] [Accepted: 07/11/2013] [Indexed: 01/10/2023]
Abstract
Tunicates are unique animals for studying the origin and evolution of vertebrates because they are considered vertebrates' closest living relatives and share the vertebrate body plan and many specific features. Both possess neural placodes, transient thickenings of the cranial ectoderm that give rise to various types of sensory cells, including axonless secondary mechanoreceptors. In vertebrates, these are represented by the hair cells of the inner ear and the lateral line, which have an apical apparatus typically bearing cilia and stereovilli. In tunicates, they are found in the coronal organ, which is a mechanoreceptor located at the base of the oral siphon along the border of the velum and tentacles and is formed of cells bearing a row of cilia and short microvilli. The coronal organ represents the best candidate homolog for the vertebrate lateral line. To further understand the evolution of secondary sensory cells, we analysed the development and cytodifferentiation of coronal cells in the tunicate ascidian Ciona intestinalis for the first time. Here, coronal sensory cells can be identified as early as larval metamorphosis, before tentacles form, as cells with short cilia and microvilli. Sensory cells gradually differentiate, acquiring hair cell features with microvilli containing actin and myosin VIIa; in the meantime, the associated supporting cells develop. The coronal organ grows throughout the animal's lifespan, accompanying the growth of the tentacle crown. Anti-phospho Histone H3 immunostaining indicates that both hair cells and supporting cells can proliferate. This finding contributes to the understanding of the evolution of secondary sensory cells, suggesting that both ancestral cell types were able to proliferate and that this property was progressively restricted to supporting cells in vertebrates and definitively lost in mammals.
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Affiliation(s)
- Fabio Gasparini
- Dipartimento di Biologia, Università di Padova, Via U. Bassi 58/B, I-35121 Padova, Italy
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14
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Caicci F, Zaniolo G, Burighel P, Degasperi V, Gasparini F, Manni L. Differentiation of papillae and rostral sensory neurons in the larva of the ascidian Botryllus schlosseri (Tunicata). J Comp Neurol 2010; 518:547-66. [PMID: 20020541 DOI: 10.1002/cne.22222] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
During the metamorphosis of tunicate ascidians, the swimming larva uses its three anterior papillae to detect the substrate for settlement, reabsorbs its chordate-like tail, and becomes a sessile oozooid. In view of the crucial role played by the anterior structures and their nerve relations, we applied electron microscopy and immunocytochemistry to study the larva of the colonial ascidian Botryllus schlosseri, following differentiation of the anterior epidermis during late embryogenesis, the larval stage, and the onset of metamorphosis. Rudiments of the papillae appear in the early tail-bud stage as ectodermic protrusions, the apexes of which differentiate into central and peripheral bipolar neurons. Axons fasciculate into two nerves direct to the brain. Distally, the long, rod-like dendritic terminations extend during the larval stage, becoming exposed to sea water. After the larva selects and adheres to the substrate, these neurons retract and regress. Adjacent to the papillae, other scattered neurons insinuate dendrites into the tunic and form the net of rostral trunk epidermal neurons (RTENs) which fasciculate together with the papillary neurons. Our data indicate that the papillae are simple and coniform, the papillary neurons are mechanoreceptors, and the RTENs are chemoreceptors. The interpapillary epidermal area, by means of an apocrine secretion, provides sticky material for temporary adhesion of the larva to the substrate.
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Affiliation(s)
- Federico Caicci
- Dipartimento di Biologia, Università degli Studi di Padova, I-35121 Padova, Italy
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15
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Degasperi V, Gasparini F, Shimeld SM, Sinigaglia C, Burighel P, Manni L. Muscle differentiation in a colonial ascidian: organisation, gene expression and evolutionary considerations. BMC DEVELOPMENTAL BIOLOGY 2009; 9:48. [PMID: 19737381 PMCID: PMC2753633 DOI: 10.1186/1471-213x-9-48] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/18/2009] [Accepted: 09/08/2009] [Indexed: 11/24/2022]
Abstract
BACKGROUND Ascidians are tunicates, the taxon recently proposed as sister group to the vertebrates. They possess a chordate-like swimming larva, which metamorphoses into a sessile adult. Several ascidian species form colonies of clonal individuals by asexual reproduction. During their life cycle, ascidians present three muscle types: striated in larval tail, striated in the heart, and unstriated in the adult body-wall. RESULTS In the colonial ascidian Botryllus schlosseri, we investigated organisation, differentiation and gene expression of muscle beginning from early buds to adults and during zooid regression. We characterised transcripts for troponin T (BsTnT-c), adult muscle-type (BsMA2) and cytoplasmic-type (BsCA1) actins, followed by in situ hybridisation (ISH) on sections to establish the spatio-temporal expression of BsTnT-c and BsMA2 during asexual reproduction and in the larva. Moreover, we characterised actin genomic sequences, which by comparison with other metazoans revealed conserved intron patterns. CONCLUSION Integration of data from ISH, phalloidin staining and TEM allowed us to follow the phases of differentiation of the three muscle kinds, which differ in expression pattern of the two transcripts. Moreover, phylogenetic analyses provided evidence for the close relationship between tunicate and vertebrate muscle genes. The characteristics and plasticity of muscles in tunicates are discussed.
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Affiliation(s)
- Valentina Degasperi
- Dipartimento di Biologia, Università degli Studi di Padova, Via Ugo Bassi 58/B, 35131, Padova, Italy
| | - Fabio Gasparini
- Dipartimento di Biologia, Università degli Studi di Padova, Via Ugo Bassi 58/B, 35131, Padova, Italy
| | - Sebastian M Shimeld
- Department of Zoology, University of Oxford, South Parks Road, Oxford OX1 3PS, UK
| | - Chiara Sinigaglia
- Dipartimento di Biologia, Università degli Studi di Padova, Via Ugo Bassi 58/B, 35131, Padova, Italy
| | - Paolo Burighel
- Dipartimento di Biologia, Università degli Studi di Padova, Via Ugo Bassi 58/B, 35131, Padova, Italy
| | - Lucia Manni
- Dipartimento di Biologia, Università degli Studi di Padova, Via Ugo Bassi 58/B, 35131, Padova, Italy
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16
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Tiozzo S, Murray M, Degnan BM, De Tomaso AW, Croll RP. Development of the neuromuscular system during asexual propagation in an invertebrate chordate. Dev Dyn 2009; 238:2081-94. [DOI: 10.1002/dvdy.22023] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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17
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Caicci F, Burighel P, Manni L. Hair cells in an ascidian (Tunicata) and their evolution in chordates. Hear Res 2007; 231:63-72. [PMID: 17611058 DOI: 10.1016/j.heares.2007.05.007] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/09/2007] [Revised: 05/09/2007] [Accepted: 05/15/2007] [Indexed: 11/19/2022]
Abstract
In ascidians, mechanoreceptors of the oral area are involved in monitoring the incoming water flow. Sensory cells are represented by scattered, ciliated primary cells (sending their own axons to the cerebral ganglion) or secondary sensory cells (axonless cells forming afferent and efferent synapses with neurons, whose somata are located in the ganglion) of the coronal organ. Coronal cells have varying morphologies: in species of the Enterogona order, they are multiciliate, whereas those of Pleurogona possess an apical apparatus composed of one or two cilia accompanied by stereovilli, in some cases also graded in length. The coronal organ has been proposed as a homologue to the vertebrate octavo-lateralis system, because coronal cells resemble vertebrate hair cells for morphology, embryonic origin and arrangement. In the ascidian Molgula socialis (Pleurogona), we now describe the morphology of the coronal organ, which contains a few associated rows of sensory cells that run the whole length of the oral velum and the branched tentacles. Three kinds of sensory cells, accompanied by specialised supporting cells, are present. Comparisons between the coronal organ and other chordate mechanosensory structures suggest that hair cells originated in the common ancestor of chordates.
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MESH Headings
- Animals
- Chordata
- Evolution, Molecular
- Hair Cells, Auditory/anatomy & histology
- Hair Cells, Auditory/metabolism
- Hair Cells, Auditory/physiology
- Hair Cells, Auditory/ultrastructure
- Mechanoreceptors
- Microscopy, Confocal
- Microscopy, Electron, Scanning
- Microscopy, Electron, Transmission
- Models, Anatomic
- Neurons, Afferent
- Phylogeny
- Urochordata/physiology
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Affiliation(s)
- F Caicci
- Department of Biology, University of Padova, Via U. Bassi 58/B, 35131 Padua, Italy.
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18
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Manni L, Zaniolo G, Cima F, Burighel P, Ballarin L. Botryllus schlosseri: a model ascidian for the study of asexual reproduction. Dev Dyn 2007; 236:335-52. [PMID: 17191252 DOI: 10.1002/dvdy.21037] [Citation(s) in RCA: 103] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Botryllus schlosseri, a cosmopolitan colonial ascidian reared in the laboratory for more than 50 years, reproduces both sexually and asexually and is used as a model organism for studying a variety of biological problems. Colonies are formed of numerous, genetically identical individuals (zooids) and undergo cyclical generation changes in which the adult zooids die and are replaced by their maturing buds. Because the progression of the colonial life cycle is intimately correlated with blastogenesis, a shared staging method of bud development is required to compare data coming from different laboratories. With the present review, we aim (1) to introduce B. schlosseri as a valuable chordate model to study various biological problems and, especially, sexual and asexual development; (2) to offer a detailed description of bud development up to adulthood and the attainment of sexual maturity; (3) to re-examine Sabbadin's (1955) staging method and re-propose it as a simple tool for in vivo recognition of the main morphogenetic events and recurrent changes in the blastogenetic cycle, as it refers to the developmental stages of buds and adults.
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Affiliation(s)
- L Manni
- Department of Biology, University of Padova, Italy.
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19
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Abstract
The programmed cell death (PCD) of developing cells is considered an essential adaptive process that evolved to serve diverse roles. We review the putative adaptive functions of PCD in the animal kingdom with a major focus on PCD in the developing nervous system. Considerable evidence is consistent with the role of PCD in events ranging from neurulation and synaptogenesis to the elimination of adult-generated CNS cells. The remarkable recent progress in our understanding of the genetic regulation of PCD has made it possible to perturb (inhibit) PCD and determine the possible repercussions for nervous system development and function. Although still in their infancy, these studies have so far revealed few striking behavioral or functional phenotypes.
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Affiliation(s)
- Robert R Buss
- Department of Neurobiology and Anatomy, Wake Forest University School of Medicine, Winston-Salem, North Carolina 27157, USA.
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20
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Tiozzo S, Ballarin L, Burighel P, Zaniolo G. Programmed cell death in vegetative development: Apoptosis during the colonial life cycle of the ascidian Botryllus schlosseri. Tissue Cell 2006; 38:193-201. [PMID: 16631832 DOI: 10.1016/j.tice.2006.02.003] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2005] [Revised: 02/17/2006] [Accepted: 02/24/2006] [Indexed: 11/25/2022]
Abstract
Programmed cell death (PCD) by apoptosis is a physiological mechanism by which cells are eliminated during embryonic and post-embryonic stages of animal life cycle. During asexual reproduction, the zooids of colonial ascidians originate from an assorted cell population instead of a single zygote, so that we assume that regulation of the equilibrium among proliferation, differentiation and cell death may follow different pathways in comparison to the embryonic development. Here we investigate the presence of apoptotic events throughout the blastogenetic life cycle of the colonial ascidian Botryllus schlosseri, by means of terminal deoxynucleotidyl transferase dUTP Nick End Labeling (TUNEL) coupled with histochemical and electron microscopy techniques. The occurrence of low levels of morphogenetic cell death suggests that, in contrast to what happens during sexual development (embryogenesis and metamorphosis), apoptosis does not play a pivotal role during asexual propagation in botryllid ascidian. Nevertheless, PCD emerges as a key force to regulate homeostasis in adult zooids and to shape and modulate the growth of the whole colony.
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Affiliation(s)
- S Tiozzo
- University of Padova, Department of Biology, via U. Bassi 58/B, 35121 Padova, Italy
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21
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Manni L, Burighel P. Common and divergent pathways in alternative developmental processes of ascidians. Bioessays 2006; 28:902-12. [PMID: 16937358 DOI: 10.1002/bies.20462] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Colonial ascidians offer opportunities to investigate how developmental events are integrated to generate the animal form, since they can develop similar individuals (oozooids from eggs, blastozooids from pluripotent somatic cells) through very different reproductive processes, i.e. embryogenesis and blastogenesis. Moreover, thanks to their key phylogenetic position, they can help in the understanding of the molecular mechanisms of morphogenesis and their evolution in chordates. We review organogenesis of the ascidian neural complex comparing embryos and buds in terms of topology, developmental mechanisms and terminology. We propose a new interpretation of bud territories, and reconsider nervous system development based on recent results suggesting that ascidians have vertebrate placodal and neural-crest-like cells. Comparing embryonic and blastogenic development in Botryllus schlosseri, we propose that the bud has territories with a placodal potentiality, suggesting that chordate ancestors possessed neurogenic placodes, and that the genetic pathways regulating neurogenic placode formation were co-opted for new developmental processes, such as blastogenesis.
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Affiliation(s)
- Lucia Manni
- Department of Biology, University of Padova, Italy.
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22
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Mackie GO, Burighel P. The nervous system in adult tunicates: current research directions. CAN J ZOOL 2005. [DOI: 10.1139/z04-177] [Citation(s) in RCA: 72] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
This review covers 25 years of progress on structural, functional, and developmental neurobiology of adult tunicates. The focus is on ascidians rather than pelagic species. The ascidian brain and peripheral nervous system are considered from the point of view of ultrastructure, neurotransmitters, regulatory peptides, and electrical activity. Sensory reception and effector control are stressed. Discussion of the dorsal strand plexus centres on its relationship with photoreceptors, the presence in it of gonadotropin-releasing hormone and its role in reproductive control. In addition to hydrodynamic sense organs based on primary sensory neurons (cupular organs), ascidians are now known to have coronal sense organs based on axonless hair cells resembling those of the vertebrate acustico-lateralis system. The peripheral nervous system is remarkable in that the motor neuron terminals are apparently interconnected synaptically, providing the equivalent of a nerve net. Development of the neural complex in ascidians is reviewed, highlighting recent embryological and molecular evidence for stomodeal, neurohypophyseal, and atrial placodes. The nervous system forms similarly during embryogenesis in the oozooid and blastogenesis in colonial forms. The regeneration of the brain in Ciona intestinalis (L., 1767) is discussed in relation to normal neurogenesis. Finally, the viviparous development of salps is considered, where recent work traces the early development of the brain, outgrowth of nerve roots, and the targetting of motor nerves to the appropriate muscles.
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23
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Burighel P, Lane NJ, Fabio G, Stefano T, Zaniolo G, Carnevali MDC, Manni L. Novel, secondary sensory cell organ in ascidians: in search of the ancestor of the vertebrate lateral line. J Comp Neurol 2003; 461:236-49. [PMID: 12724840 DOI: 10.1002/cne.10666] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
A new mechanoreceptor organ, the "coronal organ," located in the oral siphon, is described by light and electron microscopy in the colonial ascidians Botryllus schlosseri and Botrylloides violaceus. It is composed of a line of sensory cells (hair cells), accompanied by supporting cells, that runs continuously along the margin of the velum and tentacles of the siphon. These hair cells resemble those of the vertebrate lateral line or, in general, the acoustico-lateralis system, because they bear a single cilium, located centrally or eccentrically to a hair bundle of numerous stereovilli. In contrast to other sensory cells of ascidians, the coronal hair cells are secondary sensory cells, since they lack axonal processes directed towards the cerebral ganglion. Moreover, at their base they form synapses with nerve fibers, most of which exhibit acetylcholinesterase activity. The absence of axonal extensions was confirmed by experiments with lipophilic dyes. Different kinds of synapses were recognized: usually, each hair cell forms a few afferent synapses with dendrites of neurons located in the ganglion; efferent synapses, both axo-somatic (between an axon coming from the ganglion and the hair cell) and axo-dendritic (between an axon coming from the ganglion and an afferent fiber) were occasionally found. The presence of secondary sensory cells in ascidians is discussed in relation to the evolution of sensory cells and placodes in vertebrates. It is proposed that the coronal organ in urochordates is homologous to the vertebrate acoustico-lateralis system.
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Affiliation(s)
- Paolo Burighel
- Dipartimento di Biologia, Università di Padova, I-35121 Padova, Italy.
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