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Nydam ML, Saffo MB, Di Gregorio A. Women in tunicate research: Pioneers of the past and their present legacy. Genesis 2023; 61:e23578. [PMID: 38009445 DOI: 10.1002/dvg.23578] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2023] [Revised: 11/05/2023] [Accepted: 11/06/2023] [Indexed: 11/28/2023]
Abstract
The search for female scientists who pioneered the research on tunicates is hindered by the tradition of reporting only the first initials of authors' names on scientific publications using only the initials of their first names. While this practice has the theoretical merit of broadening the readership by preventing the possible bias that could be caused by the gender of the author(s) in some of the readers, it rendered the identification of female researchers active in, or before, the first half of the 20th century quite challenging. Sifting through several dozen electronic records, and with the help of references and/or quotes found online, we have stitched together the information that we were able to retrieve on the life of female scientists who authored some of the earliest publications on tunicates, and we have organized them in (approximate) chronological order. We have also compiled brief synopses of the findings of scientists active in the field of tunicate biology in more recent times, and organized them by subdiscipline.
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Affiliation(s)
- Marie L Nydam
- Life Sciences Concentration, Soka University of America, Aliso Viejo, California, USA
| | | | - Anna Di Gregorio
- Department of Molecular Pathobiology, New York University College of Dentistry, New York, New York, USA
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2
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Vitrinel B, Vogel C, Christiaen L. Ring Finger 149-Related Is an FGF/MAPK-Independent Regulator of Pharyngeal Muscle Fate Specification. Int J Mol Sci 2023; 24:8865. [PMID: 37240211 PMCID: PMC10219245 DOI: 10.3390/ijms24108865] [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: 03/13/2023] [Revised: 04/26/2023] [Accepted: 04/29/2023] [Indexed: 05/28/2023] Open
Abstract
During embryonic development, cell-fate specification gives rise to dedicated lineages that underlie tissue formation. In olfactores, which comprise tunicates and vertebrates, the cardiopharyngeal field is formed by multipotent progenitors of both cardiac and branchiomeric muscles. The ascidian Ciona is a powerful model to study cardiopharyngeal fate specification with cellular resolution, as only two bilateral pairs of multipotent cardiopharyngeal progenitors give rise to the heart and to the pharyngeal muscles (also known as atrial siphon muscles, ASM). These progenitors are multilineage primed, in as much as they express a combination of early ASM- and heart-specific transcripts that become restricted to their corresponding precursors, following oriented and asymmetric divisions. Here, we identify the primed gene ring finger 149 related (Rnf149-r), which later becomes restricted to the heart progenitors, but appears to regulate pharyngeal muscle fate specification in the cardiopharyngeal lineage. CRISPR/Cas9-mediated loss of Rnf149-r function impairs atrial siphon muscle morphogenesis, and downregulates Tbx1/10 and Ebf, two key determinants of pharyngeal muscle fate, while upregulating heart-specific gene expression. These phenotypes are reminiscent of the loss of FGF/MAPK signaling in the cardiopharyngeal lineage, and an integrated analysis of lineage-specific bulk RNA-seq profiling of loss-of-function perturbations has identified a significant overlap between candidate FGF/MAPK and Rnf149-r target genes. However, functional interaction assays suggest that Rnf149-r does not directly modulate the activity of the FGF/MAPK/Ets1/2 pathway. Instead, we propose that Rnf149-r acts both in parallel to the FGF/MAPK signaling on shared targets, as well as on FGF/MAPK-independent targets through (a) separate pathway(s).
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Affiliation(s)
- Burcu Vitrinel
- Center for Genomics and Systems Biology, Department of Biology, New York University, New York, NY 10003, USA
- Center for Developmental Genetics, Department of Biology, New York University, New York, NY 10003, USA
| | - Christine Vogel
- Center for Genomics and Systems Biology, Department of Biology, New York University, New York, NY 10003, USA
| | - Lionel Christiaen
- Center for Developmental Genetics, Department of Biology, New York University, New York, NY 10003, USA
- Michael Sars Centre, University of Bergen, P.O. Box 7800, 5020 Bergen, Norway
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3
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Zhao K, Yang Z. The second heart field: the first 20 years. Mamm Genome 2022:10.1007/s00335-022-09975-8. [PMID: 36550326 DOI: 10.1007/s00335-022-09975-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2022] [Accepted: 12/12/2022] [Indexed: 12/24/2022]
Abstract
In 2001, three independent groups reported the identification of a novel cluster of progenitor cells that contribute to heart development in mouse and chicken embryos. This population of progenitor cells was designated as the second heart field (SHF), and a new research direction in heart development was launched. Twenty years have since passed and a comprehensive understanding of the SHF has been achieved. This review provides retrospective insights in to the contribution, the signaling regulatory networks and the epithelial properties of the SHF. It also includes the spatiotemporal characteristics of SHF development and interactions between the SHF and other types of cells during heart development. Although considerable efforts will be required to investigate the cellular heterogeneity of the SHF, together with its intricate regulatory networks and undefined mechanisms, it is expected that the burgeoning new technology of single-cell sequencing and precise lineage tracing will advance the comprehension of SHF function and its molecular signals. The advances in SHF research will translate to clinical applications and to the treatment of congenital heart diseases, especially conotruncal defects, as well as to regenerative medicine.
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Affiliation(s)
- Ke Zhao
- State Key Laboratory of Pharmaceutical Biotechnology, MOE Key Laboratory of Model Animal for Disease Study, Model Animal Research Center, and Jiangsu Key Laboratory of Molecular Medicine, Nanjing University Medical School, Nanjing, 210093, China
| | - Zhongzhou Yang
- State Key Laboratory of Pharmaceutical Biotechnology, MOE Key Laboratory of Model Animal for Disease Study, Model Animal Research Center, and Jiangsu Key Laboratory of Molecular Medicine, Nanjing University Medical School, Nanjing, 210093, China.
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4
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Stutt N, Song M, Wilson MD, Scott IC. Cardiac specification during gastrulation - The Yellow Brick Road leading to Tinman. Semin Cell Dev Biol 2021; 127:46-58. [PMID: 34865988 DOI: 10.1016/j.semcdb.2021.11.011] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2021] [Revised: 11/05/2021] [Accepted: 11/11/2021] [Indexed: 02/07/2023]
Abstract
The question of how the heart develops, and the genetic networks governing this process have become intense areas of research over the past several decades. This research is propelled by classical developmental studies and potential clinical applications to understand and treat congenital conditions in which cardiac development is disrupted. Discovery of the tinman gene in Drosophila, and examination of its vertebrate homolog Nkx2.5, along with other core cardiac transcription factors has revealed how cardiac progenitor differentiation and maturation drives heart development. Careful observation of cardiac morphogenesis along with lineage tracing approaches indicated that cardiac progenitors can be divided into two broad classes of cells, namely the first and second heart fields, that contribute to the heart in two distinct waves of differentiation. Ample evidence suggests that the fate of individual cardiac progenitors is restricted to distinct cardiac structures quite early in development, well before the expression of canonical cardiac progenitor markers like Nkx2.5. Here we review the initial specification of cardiac progenitors, discuss evidence for the early patterning of cardiac progenitors during gastrulation, and consider how early gene expression programs and epigenetic patterns can direct their development. A complete understanding of when and how the developmental potential of cardiac progenitors is determined, and their potential plasticity, is of great interest developmentally and also has important implications for both the study of congenital heart disease and therapeutic approaches based on cardiac stem cell programming.
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Affiliation(s)
- Nathan Stutt
- Program in Genetics and Genome Biology, The Hospital for Sick Children, Toronto, ON M5G0A4, Canada; Department of Molecular Genetics, University of Toronto, Toronto, ON, M5S1A8, Canada
| | - Mengyi Song
- Program in Developmental and Stem Cell Biology, The Hospital for Sick Children, Toronto, ON M5G0A4, Canada; Program in Genetics and Genome Biology, The Hospital for Sick Children, Toronto, ON M5G0A4, Canada; Department of Molecular Genetics, University of Toronto, Toronto, ON, M5S1A8, Canada
| | - Michael D Wilson
- Program in Developmental and Stem Cell Biology, The Hospital for Sick Children, Toronto, ON M5G0A4, Canada; Department of Molecular Genetics, University of Toronto, Toronto, ON, M5S1A8, Canada
| | - Ian C Scott
- Program in Genetics and Genome Biology, The Hospital for Sick Children, Toronto, ON M5G0A4, Canada; Department of Molecular Genetics, University of Toronto, Toronto, ON, M5S1A8, Canada.
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Shewale B, Dubois N. Of form and function: Early cardiac morphogenesis across classical and emerging model systems. Semin Cell Dev Biol 2021; 118:107-118. [PMID: 33994301 PMCID: PMC8434962 DOI: 10.1016/j.semcdb.2021.04.025] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2021] [Revised: 04/27/2021] [Accepted: 04/28/2021] [Indexed: 12/31/2022]
Abstract
The heart is the earliest organ to develop during embryogenesis and is remarkable in its ability to function efficiently as it is being sculpted. Cardiac heart defects account for a high burden of childhood developmental disorders with many remaining poorly understood mechanistically. Decades of work across a multitude of model organisms has informed our understanding of early cardiac differentiation and morphogenesis and has simultaneously opened new and unanswered questions. Here we have synthesized current knowledge in the field and reviewed recent developments in the realm of imaging, bioengineering and genetic technology and ex vivo cardiac modeling that may be deployed to generate more holistic models of early cardiac morphogenesis, and by extension, new platforms to study congenital heart defects.
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Affiliation(s)
- Bhavana Shewale
- Department of Cell, Developmental and Regenerative Biology, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA; Mindich Child Health and Development Institute, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA; Black Family Stem Cell Institute, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
| | - Nicole Dubois
- Department of Cell, Developmental and Regenerative Biology, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA; Mindich Child Health and Development Institute, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA; Black Family Stem Cell Institute, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA.
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The pericardium of Oikopleura dioica (Tunicata, Appendicularia) contains two distinct cell types and is rotated by 90 degrees to the left. ZOOMORPHOLOGY 2021. [DOI: 10.1007/s00435-021-00538-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
AbstractThe planktonic Oikopleura dioica belongs to Tunicata, the probable sister taxon to Craniota, and might show plesiomorphic characters, conserved from the common lineage of Tunicata and Craniota. In O. dioica a pericardium in a position similar to other chordates but also to the heart and pericardium of craniates is found. Surprisingly, little is known about the ultrastructure of the pericardium in O. dioica. Here, we show based on electron microscopy that the pericardium is completely lined by a single layer of 16 epithelial cells: 6 epithelial myocardial cells on the left side of the pericardium and 10 peritoneal cells constituting the right side. One of the peritoneal cells, situated at the ventral border between peritoneal cells and myocardial cells has an extension that anchors the pericardium to the basal lamina beneath the latero-ventral epidermis. The primary body cavity of O. dioica appears quite uniformly clear in electron microscopic aspect but several sheets, resembling the basal lamina of the pericardium cross the larger spaces of the body cavity and connect to the pericardial basal lamina. This is the first detailed description of two distinct cell types in the epithelial lining of the pericardium of O. dioica. In comparison with other chordates, we conclude that two cell types can be reconstructed for the last common ancestor of Chordata at least. The position of the pericardium at the intersection of trunk and tail in combination with the basal-lamina like sheets spanning the hemocoel is probably of importance for the function of the circulation of the hemocoelic fluid. Similar to the tail, the axis of the pericardium is shifted through 90 degrees to the left as compared to the main body axis of the trunk and we infer that this shift is an apomorphic character of Appendicularia.
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The Pericardial Body of Ciona intestinalis Contains Hemocytes and Degenerating Muscle Cells, But No Parasites. Acta Parasitol 2021; 66:560-568. [PMID: 33367964 PMCID: PMC8166686 DOI: 10.1007/s11686-020-00323-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2020] [Accepted: 11/28/2020] [Indexed: 11/09/2022]
Abstract
Purpose A ventral heart positioned posterior to the branchial basket and equipped with a pericardium is homologous in tunicates and their sister group, the craniates, yet the tunicate model organism Ciona intestinalis features a pericardial body, a structure peculiar to few ascidian species. Here, we set out to distinguish between two competing hypotheses regarding the function of the pericardial body found in the literature: (H1) The pericardial body performs a role in the removal of dysfunctional myocardial cells, and (H2) it is a specialized niche of the immune system involved in defense against parasites. Methods We used histological techniques, transmission electron microscopy, and PCR-based gene sequencing to investigate whether individual ascidians parasitized with apicomplexan protists show signs of infections within the pericardial body. Results In individuals of C. intestinalis from the German North Sea infested with apicomplexan protists, the pericardial body contains numerous myocardial cells in various stages of degeneration while no remnants of parasitic cells could be identified. Conclusion Thus, we conclude that H2—the pericardial body is a specialized niche of the immune system involved in defense against parasites—can be refuted. Rather, our observations support H1, the hypothesis that the pericardial body performs a role in the removal of dysfunctional myocardial cells. Supplementary Information The online version contains supplementary material available at 10.1007/s11686-020-00323-x.
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Shim WJ, Sinniah E, Xu J, Vitrinel B, Alexanian M, Andreoletti G, Shen S, Sun Y, Balderson B, Boix C, Peng G, Jing N, Wang Y, Kellis M, Tam PPL, Smith A, Piper M, Christiaen L, Nguyen Q, Bodén M, Palpant NJ. Conserved Epigenetic Regulatory Logic Infers Genes Governing Cell Identity. Cell Syst 2020; 11:625-639.e13. [PMID: 33278344 PMCID: PMC7781436 DOI: 10.1016/j.cels.2020.11.001] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2020] [Revised: 08/31/2020] [Accepted: 11/09/2020] [Indexed: 01/06/2023]
Abstract
Determining genes that orchestrate cell differentiation in development and disease remains a fundamental goal of cell biology. This study establishes a genome-wide metric based on the gene-repressive trimethylation of histone H3 at lysine 27 (H3K27me3) across hundreds of diverse cell types to identify genetic regulators of cell differentiation. We introduce a computational method, TRIAGE, which uses discordance between gene-repressive tendency and expression to identify genetic drivers of cell identity. We apply TRIAGE to millions of genome-wide single-cell transcriptomes, diverse omics platforms, and eukaryotic cells and tissue types. Using a wide range of data, we validate the performance of TRIAGE in identifying cell-type-specific regulatory factors across diverse species including human, mouse, boar, bird, fish, and tunicate. Using CRISPR gene editing, we use TRIAGE to experimentally validate RNF220 as a regulator of Ciona cardiopharyngeal development and SIX3 as required for differentiation of endoderm in human pluripotent stem cells. A record of this paper’s transparent peer review process is included in the Supplemental Information. Perturbing genes controlling cell decisions have major implications in development or disease. However, identifying key regulatory genes from the thousands expressed in a cell is challenging. TRIAGE is a computational method that distills patterns of epigenetic repression across diverse cell types to infer regulatory genes using input gene expression data from any cell type. Demonstrating its utility, we combine single-cell RNA-seq and TRIAGE to identify and experimentally confirm novel regulators of heart development in evolutionarily distant species.
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Affiliation(s)
- Woo Jun Shim
- School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, Australia
| | - Enakshi Sinniah
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, Australia
| | - Jun Xu
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, Australia
| | - Burcu Vitrinel
- Center for Developmental Genetics, Department of Biology, New York University, New York, NY, USA
| | - Michael Alexanian
- Gladstone Institute of Cardiovascular Disease, San Francisco, CA, USA
| | - Gaia Andreoletti
- Institute for Computational Health Sciences, University of California, San Francisco, CA 94158, USA
| | - Sophie Shen
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, Australia
| | - Yuliangzi Sun
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, Australia
| | - Brad Balderson
- School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, Australia
| | - Carles Boix
- Broad Institute of MIT and Harvard, Cambridge, MA, USA
| | - Guangdun Peng
- CAS Key Laboratory of Regenerative Biology, Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences, University of Chinese Academy of Sciences and Bioland Laboratory (Guangzhou Regenerative Medicine and Health Guangdong Laboratory), Guangzhou, China; State Key Laboratory of Cell Biology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, University of Chinese Academy of Sciences, Shanghai, China
| | - Naihe Jing
- CAS Key Laboratory of Regenerative Biology, Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences, University of Chinese Academy of Sciences and Bioland Laboratory (Guangzhou Regenerative Medicine and Health Guangdong Laboratory), Guangzhou, China; State Key Laboratory of Cell Biology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, University of Chinese Academy of Sciences, Shanghai, China
| | - Yuliang Wang
- Paul G. Allen School of Computer Science and Engineering and Institute for Stem Cell & Regenerative Medicine, University of Washington, Seattle, WA, USA
| | | | - Patrick P L Tam
- The University of Sydney, Children's Medical Research Institute, and School of Medical Sciences, Faculty of Medicine and Health, Westmead, NSW 2145, Australia
| | - Aaron Smith
- Institute of Health and Biomedical Innovation, School of Biomedical Sciences, Queensland University of Technology, Brisbane, Australia; Translational Research Institute, Woolloongabba, Brisbane, Australia
| | - Michael Piper
- School of Biomedical Sciences, The University of Queensland, Brisbane, Australia; Queensland Brain Institute, The University of Queensland, Brisbane, Australia
| | - Lionel Christiaen
- Center for Developmental Genetics, Department of Biology, New York University, New York, NY, USA
| | - Quan Nguyen
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, Australia
| | - Mikael Bodén
- School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, Australia.
| | - Nathan J Palpant
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, Australia.
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9
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Hunter ES, Paight C, Lane CE. Metabolic Contributions of an Alphaproteobacterial Endosymbiont in the Apicomplexan Cardiosporidium cionae. Front Microbiol 2020; 11:580719. [PMID: 33335517 PMCID: PMC7737231 DOI: 10.3389/fmicb.2020.580719] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2020] [Accepted: 11/05/2020] [Indexed: 12/27/2022] Open
Abstract
Apicomplexa is a diverse protistan phylum composed almost exclusively of metazoan-infecting parasites, including the causative agents of malaria, cryptosporidiosis, and toxoplasmosis. A single apicomplexan genus, Nephromyces, was described in 2010 as a mutualist partner to its tunicate host. Here we present genomic and transcriptomic data from the parasitic sister species to this mutualist, Cardiosporidium cionae, and its associated bacterial endosymbiont. Cardiosporidium cionae and Nephromyces both infect tunicate hosts, localize to similar organs within these hosts, and maintain bacterial endosymbionts. Though many other protists are known to harbor bacterial endosymbionts, these associations are completely unknown in Apicomplexa outside of the Nephromycidae clade. Our data indicate that a vertically transmitted α-proteobacteria has been retained in each lineage since Nephromyces and Cardiosporidium diverged. This α-proteobacterial endosymbiont has highly reduced metabolic capabilities, but contributes the essential amino acid lysine, and essential cofactor lipoic acid to C. cionae. This partnership likely reduces resource competition with the tunicate host. However, our data indicate that the contribution of the single α-proteobacterial endosymbiont in C. cionae is minimal compared to the three taxa of endosymbionts present in the Nephromyces system, and is a potential explanation for the virulence disparity between these lineages.
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Affiliation(s)
- Elizabeth Sage Hunter
- Department of Biological Sciences, University of Rhode Island, Kingston, RI, United States
| | - Christopher Paight
- Department of Ecology, Evolution & Marine Biology, University of California, Santa Barbara, Santa Barbara, CA, United States
| | - Christopher E. Lane
- Department of Biological Sciences, University of Rhode Island, Kingston, RI, United States
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10
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Zhang T, Xu Y, Imai K, Fei T, Wang G, Dong B, Yu T, Satou Y, Shi W, Bao Z. A single-cell analysis of the molecular lineage of chordate embryogenesis. SCIENCE ADVANCES 2020; 6:eabc4773. [PMID: 33148647 PMCID: PMC7673699 DOI: 10.1126/sciadv.abc4773] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/29/2020] [Accepted: 09/16/2020] [Indexed: 05/05/2023]
Abstract
Progressive unfolding of gene expression cascades underlies diverse embryonic lineage development. Here, we report a single-cell RNA sequencing analysis of the complete and invariant embryonic cell lineage of the tunicate Ciona savignyi from fertilization to the onset of gastrulation. We reconstructed a developmental landscape of 47 cell types over eight cell cycles in the wild-type embryo and identified eight fate transformations upon fibroblast growth factor (FGF) inhibition. For most FGF-dependent asymmetric cell divisions, the bipotent mother cell displays the gene signature of the default daughter fate. In convergent differentiation of the two notochord lineages, we identified additional gene pathways parallel to the master regulator T/Brachyury Last, we showed that the defined Ciona cell types can be matched to E6.5-E8.5 stage mouse cell types and display conserved expression of limited number of transcription factors. This study provides a high-resolution single-cell dataset to understand chordate early embryogenesis and cell lineage differentiation.
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Affiliation(s)
- Tengjiao Zhang
- Institute for Regenerative Medicine, Shanghai East Hospital, School of Life Sciences and Technology, Tongji University, Shanghai 200123, China
| | - Yichi Xu
- Developmental Biology Program, Sloan Kettering Institute, New York, NY 10065, USA
| | - Kaoru Imai
- Department of Biological Sciences, Graduate School of Science, Osaka University, Toyonaka 560-0043, Japan
| | - Teng Fei
- Department of Biostatistics and Bioinformatics, Emory University, Atlanta, GA 30322, USA
| | - Guilin Wang
- Ministry of Education Key Laboratory of Marine Genetics and Breeding, College of Marine Life Sciences, Ocean University of China, Qingdao 266003, China
| | - Bo Dong
- Ministry of Education Key Laboratory of Marine Genetics and Breeding, College of Marine Life Sciences, Ocean University of China, Qingdao 266003, China
| | - Tianwei Yu
- School of Data Science, The Chinese University of Hong Kong-Shenzhen, Shenzhen, Guangdong 518172, China
| | - Yutaka Satou
- Department of Zoology, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan
| | - Weiyang Shi
- Ministry of Education Key Laboratory of Marine Genetics and Breeding, College of Marine Life Sciences, Ocean University of China, Qingdao 266003, China.
| | - Zhirong Bao
- Developmental Biology Program, Sloan Kettering Institute, New York, NY 10065, USA.
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11
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Transcription Factors of the bHLH Family Delineate Vertebrate Landmarks in the Nervous System of a Simple Chordate. Genes (Basel) 2020; 11:genes11111262. [PMID: 33114624 PMCID: PMC7693978 DOI: 10.3390/genes11111262] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2020] [Accepted: 10/12/2020] [Indexed: 02/07/2023] Open
Abstract
Tunicates are marine invertebrates whose tadpole-like larvae feature a highly simplified version of the chordate body plan. Similar to their distant vertebrate relatives, tunicate larvae develop a regionalized central nervous system and form distinct neural structures, which include a rostral sensory vesicle, a motor ganglion, and a caudal nerve cord. The sensory vesicle contains a photoreceptive complex and a statocyst, and based on the comparable expression patterns of evolutionarily conserved marker genes, it is believed to include proto-hypothalamic and proto-retinal territories. The evolutionarily conserved molecular fingerprints of these landmarks of the vertebrate brain consist of genes encoding for different transcription factors, and of the gene batteries that they control, and include several members of the bHLH family. Here we review the complement of bHLH genes present in the streamlined genome of the tunicate Ciona robusta and their current classification, and summarize recent studies on proneural bHLH transcription factors and their expression territories. We discuss the possible roles of bHLH genes in establishing the molecular compartmentalization of the enticing nervous system of this unassuming chordate.
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12
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Ferrario C, Sugni M, Somorjai IML, Ballarin L. Beyond Adult Stem Cells: Dedifferentiation as a Unifying Mechanism Underlying Regeneration in Invertebrate Deuterostomes. Front Cell Dev Biol 2020; 8:587320. [PMID: 33195242 PMCID: PMC7606891 DOI: 10.3389/fcell.2020.587320] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2020] [Accepted: 09/25/2020] [Indexed: 12/15/2022] Open
Abstract
The diversity of regenerative phenomena seen in adult metazoans, as well as their underlying mechanistic bases, are still far from being comprehensively understood. Reviewing both ultrastructural and molecular data, the present work aims to showcase the increasing relevance of invertebrate deuterostomes, i.e., echinoderms, hemichordates, cephalochordates and tunicates, as invaluable models to study cellular aspects of adult regeneration. Our comparative approach suggests a fundamental contribution of local dedifferentiation -rather than mobilization of resident undifferentiated stem cells- as an important cellular mechanism contributing to regeneration in these groups. Thus, elucidating the cellular origins, recruitment and fate of cells, as well as the molecular signals underpinning tissue regrowth in regeneration-competent deuterostomes, will provide the foundation for future research in tackling the relatively limited regenerative abilities of vertebrates, with clear applications in regenerative medicine.
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Affiliation(s)
- Cinzia Ferrario
- Department of Environmental Science and Policy, University of Milan, Milan, Italy
- Center for Complexity and Biosystems, Department of Physics, University of Milan, Milan, Italy
| | - Michela Sugni
- Department of Environmental Science and Policy, University of Milan, Milan, Italy
- Center for Complexity and Biosystems, Department of Physics, University of Milan, Milan, Italy
- GAIA 2050 Center, Department of Environmental Science and Policy, University of Milan, Milan, Italy
| | - Ildiko M. L. Somorjai
- The Willie Russel Laboratories, Biomedical Sciences Research Complex, North Haugh, University of St Andrews, St Andrews, United Kingdom
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13
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Zullo L, Bozzo M, Daya A, Di Clemente A, Mancini FP, Megighian A, Nesher N, Röttinger E, Shomrat T, Tiozzo S, Zullo A, Candiani S. The Diversity of Muscles and Their Regenerative Potential across Animals. Cells 2020; 9:cells9091925. [PMID: 32825163 PMCID: PMC7563492 DOI: 10.3390/cells9091925] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2020] [Revised: 08/14/2020] [Accepted: 08/17/2020] [Indexed: 02/06/2023] Open
Abstract
Cells with contractile functions are present in almost all metazoans, and so are the related processes of muscle homeostasis and regeneration. Regeneration itself is a complex process unevenly spread across metazoans that ranges from full-body regeneration to partial reconstruction of damaged organs or body tissues, including muscles. The cellular and molecular mechanisms involved in regenerative processes can be homologous, co-opted, and/or evolved independently. By comparing the mechanisms of muscle homeostasis and regeneration throughout the diversity of animal body-plans and life cycles, it is possible to identify conserved and divergent cellular and molecular mechanisms underlying muscle plasticity. In this review we aim at providing an overview of muscle regeneration studies in metazoans, highlighting the major regenerative strategies and molecular pathways involved. By gathering these findings, we wish to advocate a comparative and evolutionary approach to prompt a wider use of “non-canonical” animal models for molecular and even pharmacological studies in the field of muscle regeneration.
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Affiliation(s)
- Letizia Zullo
- Istituto Italiano di Tecnologia, Center for Micro-BioRobotics & Center for Synaptic Neuroscience and Technology (NSYN), 16132 Genova, Italy;
- IRCCS Ospedale Policlinico San Martino, 16132 Genova, Italy
- Correspondence: (L.Z.); (A.Z.)
| | - Matteo Bozzo
- Laboratory of Developmental Neurobiology, Department of Earth, Environment and Life Sciences, University of Genova, Viale Benedetto XV 5, 16132 Genova, Italy; (M.B.); (S.C.)
| | - Alon Daya
- Faculty of Marine Sciences, Ruppin Academic Center, Michmoret 40297, Israel; (A.D.); (N.N.); (T.S.)
| | - Alessio Di Clemente
- Istituto Italiano di Tecnologia, Center for Micro-BioRobotics & Center for Synaptic Neuroscience and Technology (NSYN), 16132 Genova, Italy;
- Department of Experimental Medicine, University of Genova, Viale Benedetto XV, 3, 16132 Genova, Italy
| | | | - Aram Megighian
- Department of Biomedical Sciences, University of Padova, 35131 Padova, Italy;
- Padova Neuroscience Center, University of Padova, 35131 Padova, Italy
| | - Nir Nesher
- Faculty of Marine Sciences, Ruppin Academic Center, Michmoret 40297, Israel; (A.D.); (N.N.); (T.S.)
| | - Eric Röttinger
- Institute for Research on Cancer and Aging (IRCAN), Université Côte d’Azur, CNRS, INSERM, 06107 Nice, France;
| | - Tal Shomrat
- Faculty of Marine Sciences, Ruppin Academic Center, Michmoret 40297, Israel; (A.D.); (N.N.); (T.S.)
| | - Stefano Tiozzo
- Laboratoire de Biologie du Développement de Villefranche-sur-Mer (LBDV), Sorbonne Université, CNRS, 06230 Paris, France;
| | - Alberto Zullo
- Department of Science and Technology, University of Sannio, 82100 Benevento, Italy;
- Correspondence: (L.Z.); (A.Z.)
| | - Simona Candiani
- Laboratory of Developmental Neurobiology, Department of Earth, Environment and Life Sciences, University of Genova, Viale Benedetto XV 5, 16132 Genova, Italy; (M.B.); (S.C.)
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14
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The ventral peptidergic system of the adult ascidian Ciona robusta (Ciona intestinalis Type A) insights from a transgenic animal model. Sci Rep 2020; 10:1892. [PMID: 32024913 PMCID: PMC7002689 DOI: 10.1038/s41598-020-58884-w] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2019] [Accepted: 01/14/2020] [Indexed: 12/12/2022] Open
Abstract
Ascidians are the sister group of vertebrates and occupy a critical position in explorations of the evolution of the endocrine and nervous systems of chordates. Here, we describe the complete ventral peptidergic system in adult transgenic Ciona robusta (Ciona intestinalis Type A) which expresses the Kaede reporter gene driven by the prohormone convertase 2 (PC2) gene promoter. Numerous PC2 promoter-driven fluorescent (Kaede-positive) non-neural cells were distributed in the blood sinus located at the anterior end of the pharynx, suggesting the acquisition of a peptidergic circulatory system in Ciona. Kaede-positive ciliated columnar cells, rounded cells, and tall ciliated cells were observed in the alimentary organs, including the endostyle, pharynx, esophagus, stomach, and intestine, suggesting that digestive functions are regulated by multiple peptidergic systems. In the heart, Kaede-positive neurons were located in the ring-shaped plexus at both ends of the myocardium. Nerve fiber-like tracts ran along the raphe and appeared to be connected with the plexuses. Such unique structures suggest a role for the peptidergic system in cardiac function. Collectively, the present anatomic analysis revealed the major framework of the ventral peptidergic system of adult Ciona, which could facilitate investigations of peptidergic regulation of the pharynx, endostyle, alimentary tissues, and heart.
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15
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Colgan W, Leanza A, Hwang A, DeBiasse MB, Llosa I, Rodrigues D, Adhikari H, Barreto Corona G, Bock S, Carillo-Perez A, Currie M, Darkoa-Larbi S, Dellal D, Gutow H, Hokama P, Kibby E, Linhart N, Moody S, Naganuma A, Nguyen D, Stanton R, Stark S, Tumey C, Velleca A, Ryan JF, Davidson B. Variable levels of drift in tunicate cardiopharyngeal gene regulatory elements. EvoDevo 2019; 10:24. [PMID: 31632631 PMCID: PMC6790052 DOI: 10.1186/s13227-019-0137-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2019] [Accepted: 09/13/2019] [Indexed: 12/29/2022] Open
Abstract
BACKGROUND Mutations in gene regulatory networks often lead to genetic divergence without impacting gene expression or developmental patterning. The rules governing this process of developmental systems drift, including the variable impact of selective constraints on different nodes in a gene regulatory network, remain poorly delineated. RESULTS Here we examine developmental systems drift within the cardiopharyngeal gene regulatory networks of two tunicate species, Corella inflata and Ciona robusta. Cross-species analysis of regulatory elements suggests that trans-regulatory architecture is largely conserved between these highly divergent species. In contrast, cis-regulatory elements within this network exhibit distinct levels of conservation. In particular, while most of the regulatory elements we analyzed showed extensive rearrangements of functional binding sites, the enhancer for the cardiopharyngeal transcription factor FoxF is remarkably well-conserved. Even minor alterations in spacing between binding sites lead to loss of FoxF enhancer function, suggesting that bound trans-factors form position-dependent complexes. CONCLUSIONS Our findings reveal heterogeneous levels of divergence across cardiopharyngeal cis-regulatory elements. These distinct levels of divergence presumably reflect constraints that are not clearly associated with gene function or position within the regulatory network. Thus, levels of cis-regulatory divergence or drift appear to be governed by distinct structural constraints that will be difficult to predict based on network architecture.
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Affiliation(s)
| | - Alexis Leanza
- Thomas Jefferson University Sidney Kimmel Medical College, Philadelphia, USA
| | - Ariel Hwang
- University of North Carolina, Chapel Hill, USA
| | | | | | | | | | | | | | | | | | | | - Daniel Dellal
- Icahn School of Medicine at Mount Sinai, New York, USA
| | | | | | - Emily Kibby
- University of Colorado Boulder, Boulder, USA
| | | | | | | | | | | | - Sierra Stark
- University of California San Francisco, San Francisco, USA
| | | | | | - Joseph F. Ryan
- Whitney Laboratory for Marine Bioscience, St. Augustine, USA
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16
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Abstract
The vertebrate heart tube forms from epithelial progenitor cells in the early embryo and subsequently elongates by progressive addition of second heart field (SHF) progenitor cells from adjacent splanchnic mesoderm. Failure to maximally elongate the heart results in a spectrum of morphological defects affecting the cardiac poles, including outflow tract alignment and atrioventricular septal defects, among the most common congenital birth anomalies. SHF cells constitute an atypical apicobasally polarized epithelium with dynamic basal filopodia, located in the dorsal wall of the pericardial cavity. Recent studies have highlighted the importance of epithelial architecture and cell adhesion in the SHF, particularly for signaling events that control the progenitor cell niche during heart tube elongation. The 22q11.2 deletion syndrome gene Tbx1 regulates progenitor cell status through modulating cell shape and filopodial activity and is required for SHF contributions to both cardiac poles. Noncanonical Wnt signaling and planar cell polarity pathway genes control epithelial polarity in the dorsal pericardial wall, as progenitor cells differentiate in a transition zone at the arterial pole. Defects in these pathways lead to outflow tract shortening. Moreover, new biomechanical models of heart tube elongation have been proposed based on analysis of tissue-wide forces driving epithelial morphogenesis in the SHF, including regional cell intercalation, cell cohesion, and epithelial tension. Regulation of the epithelial properties of SHF cells is thus emerging as a key step during heart tube elongation, adding a new facet to our understanding of the mechanisms underlying both heart morphogenesis and congenital heart defects.
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Affiliation(s)
- Claudio Cortes
- From Aix-Marseille University, CNRS UMR 7288, Developmental Biology Institute of Marseille, France
| | - Alexandre Francou
- From Aix-Marseille University, CNRS UMR 7288, Developmental Biology Institute of Marseille, France
| | - Christopher De Bono
- From Aix-Marseille University, CNRS UMR 7288, Developmental Biology Institute of Marseille, France
| | - Robert G Kelly
- From Aix-Marseille University, CNRS UMR 7288, Developmental Biology Institute of Marseille, France.
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17
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A single-cell transcriptional roadmap for cardiopharyngeal fate diversification. Nat Cell Biol 2019; 21:674-686. [PMID: 31160712 PMCID: PMC7491489 DOI: 10.1038/s41556-019-0336-z] [Citation(s) in RCA: 44] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2019] [Accepted: 04/29/2019] [Indexed: 01/06/2023]
Abstract
In vertebrates, multipotent progenitors located in the pharyngeal mesoderm form cardiomyocytes and branchiomeric head muscles, but the dynamic gene expression programmes and mechanisms underlying cardiopharyngeal multipotency and heart versus head muscle fate choices remain elusive. Here, we used single-cell genomics in the simple chordate model Ciona to reconstruct developmental trajectories forming first and second heart lineages and pharyngeal muscle precursors and characterize the molecular underpinnings of cardiopharyngeal fate choices. We show that FGF-MAPK signalling maintains multipotency and promotes the pharyngeal muscle fate, whereas signal termination permits the deployment of a pan-cardiac programme, shared by the first and second heart lineages, to define heart identity. In the second heart lineage, a Tbx1/10-Dach pathway actively suppresses the first heart lineage programme, conditioning later cell diversity in the beating heart. Finally, cross-species comparisons between Ciona and the mouse evoke the deep evolutionary origins of cardiopharyngeal networks in chordates.
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18
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Poelmann RE, Gittenberger-de Groot AC. Development and evolution of the metazoan heart. Dev Dyn 2019; 248:634-656. [PMID: 31063648 PMCID: PMC6767493 DOI: 10.1002/dvdy.45] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2019] [Revised: 04/25/2019] [Accepted: 04/29/2019] [Indexed: 12/19/2022] Open
Abstract
The mechanisms of the evolution and development of the heart in metazoans are highlighted, starting with the evolutionary origin of the contractile cell, supposedly the precursor of cardiomyocytes. The last eukaryotic common ancestor is likely a combination of several cellular organisms containing their specific metabolic pathways and genetic signaling networks. During evolution, these tool kits diversified. Shared parts of these conserved tool kits act in the development and functioning of pumping hearts and open or closed circulations in such diverse species as arthropods, mollusks, and chordates. The genetic tool kits became more complex by gene duplications, addition of epigenetic modifications, influence of environmental factors, incorporation of viral genomes, cardiac changes necessitated by air‐breathing, and many others. We evaluate mechanisms involved in mollusks in the formation of three separate hearts and in arthropods in the formation of a tubular heart. A tubular heart is also present in embryonic stages of chordates, providing the septated four‐chambered heart, in birds and mammals passing through stages with first and second heart fields. The four‐chambered heart permits the formation of high‐pressure systemic and low‐pressure pulmonary circulation in birds and mammals, allowing for high metabolic rates and maintenance of body temperature. Crocodiles also have a (nearly) separated circulation, but their resting temperature conforms with the environment. We argue that endothermic ancestors lost the capacity to elevate their body temperature during evolution, resulting in ectothermic modern crocodilians. Finally, a clinically relevant paragraph reviews the occurrence of congenital cardiac malformations in humans as derailments of signaling pathways during embryonic development. The cardiac regulatory toolkit contains many factors including epigenetic, genetic, viral, hemodynamic, and environmental factors, but also transcriptional activators, repressors, duplicated genes, redundancies and dose‐dependancies. Numerous toolkits regulate mechanisms including cell‐cell interactions, EMT, mitosis patterns, cell migration and differentiation and left/right sidedness involved in the development of endocardial cushions, looping, septum complexes, pharyngeal arch arteries, chamber and valve formation and conduction system. Evolutionary development of the yolk sac circulation likely preceded the advent of endothermy in amniotes. Parallel evolutionary traits regulate the development of contractile pumps in various taxa often in conjunction with the gut, lungs and excretory organs.
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Affiliation(s)
- Robert E Poelmann
- Institute of Biology, Department of Animal Sciences and Health, Leiden University, Leiden, The Netherlands.,Department of Cardiology, Leiden University Medical Center, Leiden, The Netherlands
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19
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Athanasiadou R, Neymotin B, Brandt N, Wang W, Christiaen L, Gresham D, Tranchina D. A complete statistical model for calibration of RNA-seq counts using external spike-ins and maximum likelihood theory. PLoS Comput Biol 2019; 15:e1006794. [PMID: 30856174 PMCID: PMC6428340 DOI: 10.1371/journal.pcbi.1006794] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2018] [Revised: 03/21/2019] [Accepted: 01/16/2019] [Indexed: 01/09/2023] Open
Abstract
A fundamental assumption, common to the vast majority of high-throughput transcriptome analyses, is that the expression of most genes is unchanged among samples and that total cellular RNA remains constant. As the number of analyzed experimental systems increases however, different independent studies demonstrate that this assumption is often violated. We present a calibration method using RNA spike-ins that allows for the measurement of absolute cellular abundance of RNA molecules. We apply the method to pooled RNA from cell populations of known sizes. For each transcript, we compute a nominal abundance that can be converted to absolute by dividing by a scale factor determined in separate experiments: the yield coefficient of the transcript relative to that of a reference spike-in measured with the same protocol. The method is derived by maximum likelihood theory in the context of a complete statistical model for sequencing counts contributed by cellular RNA and spike-ins. The counts are based on a sample from a fixed number of cells to which a fixed population of spike-in molecules has been added. We illustrate and evaluate the method with applications to two global expression data sets, one from the model eukaryote Saccharomyces cerevisiae, proliferating at different growth rates, and differentiating cardiopharyngeal cell lineages in the chordate Ciona robusta. We tested the method in a technical replicate dilution study, and in a k-fold validation study.
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Affiliation(s)
- Rodoniki Athanasiadou
- Center for Genomics and Systems Biology, Department of Biology, New York University, New York, New York, United States of America
| | - Benjamin Neymotin
- Center for Genomics and Systems Biology, Department of Biology, New York University, New York, New York, United States of America
| | - Nathan Brandt
- Center for Genomics and Systems Biology, Department of Biology, New York University, New York, New York, United States of America
| | - Wei Wang
- Center for Developmental Genetics, Department of Biology, New York University, New York, New York, United States of America
| | - Lionel Christiaen
- Center for Developmental Genetics, Department of Biology, New York University, New York, New York, United States of America
| | - David Gresham
- Center for Genomics and Systems Biology, Department of Biology, New York University, New York, New York, United States of America
| | - Daniel Tranchina
- Department of Biology, New York University, New York, New York, United States of America
- Courant Institute of Mathematical Sciences, New York University, New York, New York, United States of America
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20
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Transgenic Techniques for Investigating Cell Biology During Development. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2018. [PMID: 29542088 DOI: 10.1007/978-981-10-7545-2_14] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Ascidians are increasingly being used as a system for investigating cell biology during development. The extreme genetic and cellular simplicity of ascidian embryos in combination with superior experimental tractability make this an ideal system for in vivo analysis of dynamic cellular processes. Transgenic approaches to cellular and sub-cellular analysis of ascidian development have begun to yield new insights into the mechanisms regulating developmental signaling and morphogenesis. This chapter focuses on the targeted expression of fusion proteins in ascidian embryos and how this technique is being deployed to garner new insights into the cell biology of development.
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21
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Sasakura Y, Hozumi A. Formation of adult organs through metamorphosis in ascidians. WILEY INTERDISCIPLINARY REVIEWS-DEVELOPMENTAL BIOLOGY 2017; 7. [PMID: 29105358 DOI: 10.1002/wdev.304] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/09/2017] [Revised: 08/28/2017] [Accepted: 09/11/2017] [Indexed: 02/05/2023]
Abstract
The representative characteristic of ascidians is their vertebrate-like, tadpole shape at the larval stage. Ascidians lose the tadpole shape through metamorphosis to become adults with a nonmotile, sessile body and a shape generally considered distinct from that of vertebrates. Solitary ascidians including Ciona species are extensively studied to understand the developmental mechanisms of ascidians, and to compare these mechanisms with their counterparts in vertebrates. In these ascidian species, the digestive and circulatory systems are not well developed in the larval trunk and the larvae do not take food. This is in contrast with the inner conditions of vertebrate tadpoles, which have functional organs comparable to those of adults. The adult organs and tissues of these ascidians become functional during metamorphosis that is completed quickly, suggesting that the ascidian larvae of solitary species are a transient stage of development. We here discuss how the cells and tissues in the ascidian larval body are converted into those of adults. The hearts of ascidians and vertebrates use closely related cellular and molecular mechanisms that suggest their shared origin. Hox genes of ascidians are essential for forming adult endodermal structures. To fully understand the development and evolution of chordates, a complete elucidation of the mechanisms underlying the adult tissue/organ formation of ascidians will be needed. WIREs Dev Biol 2018, 7:e304. doi: 10.1002/wdev.304 This article is categorized under: Comparative Development and Evolution > Body Plan Evolution Early Embryonic Development > Development to the Basic Body Plan.
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Affiliation(s)
- Yasunori Sasakura
- Shimoda Marine Research Center, University of Tsukuba, Shimoda, Shizuoka, Japan
| | - Akiko Hozumi
- Shimoda Marine Research Center, University of Tsukuba, Shimoda, Shizuoka, Japan
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