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Martí-Solans J, Børve A, Bump P, Hejnol A, Lynagh T. Peripheral and central employment of acid-sensing ion channels during early bilaterian evolution. eLife 2023; 12:81613. [PMID: 36821351 PMCID: PMC9949801 DOI: 10.7554/elife.81613] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2022] [Accepted: 01/08/2023] [Indexed: 02/24/2023] Open
Abstract
Nervous systems are endowed with rapid chemosensation and intercellular signaling by ligand-gated ion channels (LGICs). While a complex, bilaterally symmetrical nervous system is a major innovation of bilaterian animals, the employment of specific LGICs during early bilaterian evolution is poorly understood. We therefore questioned bilaterian animals' employment of acid-sensing ion channels (ASICs), LGICs that mediate fast excitatory responses to decreases in extracellular pH in vertebrate neurons. Our phylogenetic analysis identified an earlier emergence of ASICs from the overarching DEG/ENaC (degenerin/epithelial sodium channel) superfamily than previously thought and suggests that ASICs were a bilaterian innovation. Our broad examination of ASIC gene expression and biophysical function in each major bilaterian lineage of Xenacoelomorpha, Protostomia, and Deuterostomia suggests that the earliest bilaterian ASICs were probably expressed in the periphery, before being incorporated into the brain as it emerged independently in certain deuterostomes and xenacoelomorphs. The loss of certain peripheral cells from Ecdysozoa after they separated from other protostomes likely explains their loss of ASICs, and thus the absence of ASICs from model organisms Drosophila and Caenorhabditis elegans. Thus, our use of diverse bilaterians in the investigation of LGIC expression and function offers a unique hypothesis on the employment of LGICs in early bilaterian evolution.
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Affiliation(s)
| | - Aina Børve
- Department of Biological Sciences, University of BergenBergenNorway
| | - Paul Bump
- Hopkins Marine Station, Department of Biology, Stanford UniversityPacific GroveUnited States
| | - Andreas Hejnol
- Department of Biological Sciences, University of BergenBergenNorway
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2
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Wisuthiphaet N, Yang X, Young GM, Nitin N. Application of Engineered Bacteriophage T7 in the Detection of Bacteria in Food Matrices. Front Microbiol 2021; 12:691003. [PMID: 34421846 PMCID: PMC8377434 DOI: 10.3389/fmicb.2021.691003] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2021] [Accepted: 07/12/2021] [Indexed: 11/13/2022] Open
Abstract
Detection of pathogens in a food matrix is challenging due to various constraints including complexity and the cost of sample preparation for microbial analysis from food samples, time period for the detection of pathogens, and high cost and specialized resources required for advanced molecular assays. To address some of these key challenges, this study illustrates a simple and rapid colorimetric detection of target bacteria in distinct food matrices, including fresh produce, without prior isolation of bacteria from a food matrix. This approach combines bacteriophage-induced expression of an exogenous enzyme, alkaline phosphatase, the specific colorimetric substrate that generates insoluble color products, and a simple filtration method to localize the generation of colored signal. Using this approach, this study demonstrates the specific detection of inoculated Escherichia coli in coconut water and baby spinach leaves. Without isolating bacteria from the selected food matrices and using a food sample size that is representative of industrial samples, the inoculated samples were added to the enrichment broth for a short period (5 h) and incubated with an engineered bacteriophage T7 with a phoA gene. The incubation period with the engineered bacteriophage was 30 min for liquid samples and 2 h for fresh produce samples. The samples were then filtered through a 0.2-micron polycarbonate membrane and incubated with a colorimetric substrate, i.e., nitro blue tetrazolium/5-bromo-4-chloro-3-indolyl phosphate (NBT/BCIP). This substrate forms a dark purple precipitate upon interactions with the released enzyme on a filter membrane. This approach successfully detected 10 CFU/ml of E. coli in coconut water and 102 CFU/g of E. coli on baby spinach leaves with 5 h of enrichment. Success of this approach illustrates potential for detecting target bacteria in food systems using a simple visual assay and/or quantitative colorimetric measurements.
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Affiliation(s)
- Nicharee Wisuthiphaet
- Department of Food Science and Technology, University of California, Davis, Davis, CA, United States
| | - Xu Yang
- Department of Nutrition and Food Science, California State Polytechnic University Pomona, Pomona, CA, United States
| | - Glenn M Young
- Department of Food Science and Technology, University of California, Davis, Davis, CA, United States
| | - Nitin Nitin
- Department of Food Science and Technology, University of California, Davis, Davis, CA, United States.,Department of Biological and Agricultural Engineering, University of California, Davis, Davis, CA, United States
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3
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Genes with spiralian-specific protein motifs are expressed in spiralian ciliary bands. Nat Commun 2020; 11:4171. [PMID: 32820176 PMCID: PMC7441323 DOI: 10.1038/s41467-020-17780-7] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2019] [Accepted: 07/17/2020] [Indexed: 12/22/2022] Open
Abstract
Spiralia is a large, ancient and diverse clade of animals, with a conserved early developmental program but diverse larval and adult morphologies. One trait shared by many spiralians is the presence of ciliary bands used for locomotion and feeding. To learn more about spiralian-specific traits we have examined the expression of 20 genes with protein motifs that are strongly conserved within the Spiralia, but not detectable outside of it. Here, we show that two of these are specifically expressed in the main ciliary band of the mollusc Tritia (also known as Ilyanassa). Their expression patterns in representative species from five more spiralian phyla—the annelids, nemerteans, phoronids, brachiopods and rotifers—show that at least one of these, lophotrochin, has a conserved and specific role in particular ciliated structures, most consistently in ciliary bands. These results highlight the potential importance of lineage-specific genes or protein motifs for understanding traits shared across ancient lineages. Spiralians have ciliary bands, used for locomotion and feeding, but defining molecular features of these structures are unknown. Here, the authors report a gene, Lophotrochin, that contains a protein domain only found in spiralians, and specifically expressed in diverse ciliary bands across the group, which provides a molecular signature for these structures.
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4
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Bozzo M, Candiani S, Schubert M. Whole mount in situ hybridization and immunohistochemistry for studying retinoic acid signaling in developing amphioxus. Methods Enzymol 2020; 637:419-452. [PMID: 32359654 DOI: 10.1016/bs.mie.2020.03.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/15/2023]
Abstract
Retinoic acid (RA) is a vitamin A-derived signaling molecule acting during development and in the adult. This chapter provides protocols to characterize the role of RA signaling during development of the invertebrate chordate amphioxus. As sister group to all other chordates and characterized by the most vertebrate-like RA signaling system of all invertebrates, amphioxus is an important model for studying the evolution of RA signaling. Focusing on the development of GABAergic neurons in the amphioxus central nervous system, we provide detailed protocols for maintaining and breeding adult animals, for performing pharmacological treatments of embryos and for analyzing the effects of these treatments by whole mount in situ hybridization and immunohistochemistry coupled to confocal microscopy.
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Affiliation(s)
- Matteo Bozzo
- Laboratory of Developmental Neurobiology, Department of Earth, Environment and Life Sciences, University of Genoa, Genoa, Italy
| | - Simona Candiani
- Laboratory of Developmental Neurobiology, Department of Earth, Environment and Life Sciences, University of Genoa, Genoa, Italy
| | - Michael Schubert
- Sorbonne Université, CNRS, Laboratoire de Biologie du Développement de Villefranche-sur-Mer, Villefranche-sur-Mer, France.
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5
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Young AP, Jackson DJ, Wyeth RC. A technical review and guide to RNA fluorescence in situ hybridization. PeerJ 2020; 8:e8806. [PMID: 32219032 PMCID: PMC7085896 DOI: 10.7717/peerj.8806] [Citation(s) in RCA: 53] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2019] [Accepted: 02/25/2020] [Indexed: 12/20/2022] Open
Abstract
RNA-fluorescence in situ hybridization (FISH) is a powerful tool to visualize target messenger RNA transcripts in cultured cells, tissue sections or whole-mount preparations. As the technique has been developed over time, an ever-increasing number of divergent protocols have been published. There is now a broad selection of options available to facilitate proper tissue preparation, hybridization, and post-hybridization background removal to achieve optimal results. Here we review the technical aspects of RNA-FISH, examining the most common methods associated with different sample types including cytological preparations and whole-mounts. We discuss the application of commonly used reagents for tissue preparation, hybridization, and post-hybridization washing and provide explanations of the functional roles for each reagent. We also discuss the available probe types and necessary controls to accurately visualize gene expression. Finally, we review the most recent advances in FISH technology that facilitate both highly multiplexed experiments and signal amplification for individual targets. Taken together, this information will guide the methods development process for investigators that seek to perform FISH in organisms that lack documented or optimized protocols.
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Affiliation(s)
- Alexander P Young
- Department of Biology, St. Francis Xavier University, Antigonish, NS, Canada
| | - Daniel J Jackson
- Department of Geobiology, Georg-August Universität Göttingen, Göttingen, Germany
| | - Russell C Wyeth
- Department of Biology, St. Francis Xavier University, Antigonish, NS, Canada
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6
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Vopalensky P, Tosches MA, Achim K, Handberg-Thorsager M, Arendt D. From spiral cleavage to bilateral symmetry: the developmental cell lineage of the annelid brain. BMC Biol 2019; 17:81. [PMID: 31640768 PMCID: PMC6805352 DOI: 10.1186/s12915-019-0705-x] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2019] [Accepted: 10/01/2019] [Indexed: 11/15/2022] Open
Abstract
BACKGROUND During early development, patterns of cell division-embryonic cleavage-accompany the gradual restriction of blastomeres to specific cell fates. In Spiralia, which include annelids, mollusks, and flatworms, "spiral cleavage" produces a highly stereotypic, spiral-like arrangement of blastomeres and swimming trochophore-type larvae with rotational (spiral) symmetry. However, starting at larval stages, spiralian larvae acquire elements of bilateral symmetry, before they metamorphose into fully bilateral juveniles. How this spiral-to-bilateral transition occurs is not known and is especially puzzling for the early differentiating brain and head sensory organs, which emerge directly from the spiral cleavage pattern. Here we present the developmental cell lineage of the Platynereis larval episphere. RESULTS Live-imaging recordings from the zygote to the mid-trochophore stage (~ 30 hpf) of the larval episphere of the marine annelid Platynereis dumerilii reveal highly stereotypical development and an invariant cell lineage of early differentiating cell types. The larval brain and head sensory organs develop from 11 pairs of bilateral founders, each giving rise to identical clones on the right and left body sides. Relating the origin of each bilateral founder pair back to the spiral cleavage pattern, we uncover highly divergent origins: while some founder pairs originate from corresponding cells in the spiralian lineage on each body side, others originate from non-corresponding cells, and yet others derive from a single cell within one quadrant. Integrating lineage and gene expression data for several embryonic and larval stages, we find that the conserved head patterning genes otx and six3 are expressed in bilateral founders representing divergent lineage histories and giving rise to early differentiating cholinergic neurons and head sensory organs, respectively. CONCLUSIONS We present the complete developmental cell lineage of the Platynereis larval episphere, and thus the first comprehensive account of the spiral-to-bilateral transition in a developing spiralian. The bilateral symmetry of the head emerges from pairs of bilateral founders, similar to the trunk; however, the head founders are more numerous and show striking left-right asymmetries in lineage behavior that we relate to differential gene expression.
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Affiliation(s)
- Pavel Vopalensky
- Developmental Biology Unit, European Molecular Biology Laboratory, Meyerhofstraße 1, 69117, Heidelberg, Germany
| | - Maria Antonietta Tosches
- Developmental Biology Unit, European Molecular Biology Laboratory, Meyerhofstraße 1, 69117, Heidelberg, Germany
| | - Kaia Achim
- Developmental Biology Unit, European Molecular Biology Laboratory, Meyerhofstraße 1, 69117, Heidelberg, Germany
| | - Mette Handberg-Thorsager
- Developmental Biology Unit, European Molecular Biology Laboratory, Meyerhofstraße 1, 69117, Heidelberg, Germany
- Max Planck Institute of Molecular Cell Biology and Genetics, Pfotenhauerstraße 108, Dresden, 01307, Germany
| | - Detlev Arendt
- Developmental Biology Unit, European Molecular Biology Laboratory, Meyerhofstraße 1, 69117, Heidelberg, Germany.
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7
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Lin C, Chiu P, Hsueh Y, Shieh S, Wu C, Wong T, Chuong C, Hughes MW. Regeneration of rete ridges in Lanyu pig (
Sus scrofa
): Insights for human skin wound healing. Exp Dermatol 2019; 28:472-479. [DOI: 10.1111/exd.13875] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2018] [Revised: 12/23/2018] [Accepted: 01/07/2019] [Indexed: 12/28/2022]
Affiliation(s)
- Chein‐Hong Lin
- International Center for Wound Repair and RegenerationNational Cheng Kung University Tainan Taiwan
- Department of Basic MedicineCollege of MedicineNational Cheng Kung University Tainan Taiwan
| | - Po‐Yuan Chiu
- International Center for Wound Repair and RegenerationNational Cheng Kung University Tainan Taiwan
- Institute of Clinical MedicineNational Cheng Kung University Hospital Tainan Taiwan
| | - Yuan‐Yu Hsueh
- International Center for Wound Repair and RegenerationNational Cheng Kung University Tainan Taiwan
- Division of Plastic and Reconstructive SurgeryDepartment of SurgeryNational Cheng Kung University Hospital Tainan Taiwan
| | - Shyh‐Jou Shieh
- International Center for Wound Repair and RegenerationNational Cheng Kung University Tainan Taiwan
- Division of Plastic and Reconstructive SurgeryDepartment of SurgeryNational Cheng Kung University Hospital Tainan Taiwan
| | - Chia‐Ching Wu
- International Center for Wound Repair and RegenerationNational Cheng Kung University Tainan Taiwan
- Department of Basic MedicineCollege of MedicineNational Cheng Kung University Tainan Taiwan
| | - Tak‐Wah Wong
- Department of DermatologyNational Cheng Kung University Hospital Tainan Taiwan
| | - Cheng‐Ming Chuong
- International Center for Wound Repair and RegenerationNational Cheng Kung University Tainan Taiwan
- Department of Basic MedicineCollege of MedicineNational Cheng Kung University Tainan Taiwan
- Institute of Clinical MedicineNational Cheng Kung University Hospital Tainan Taiwan
- Department of PathologyUniversity of Southern California Los Angeles California
| | - Michael W. Hughes
- International Center for Wound Repair and RegenerationNational Cheng Kung University Tainan Taiwan
- Institute of Clinical MedicineNational Cheng Kung University Hospital Tainan Taiwan
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8
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Thiel D, Bauknecht P, Jékely G, Hejnol A. An ancient FMRFamide-related peptide-receptor pair induces defence behaviour in a brachiopod larva. Open Biol 2018; 7:rsob.170136. [PMID: 28835571 PMCID: PMC5577450 DOI: 10.1098/rsob.170136] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2017] [Accepted: 07/25/2017] [Indexed: 11/22/2022] Open
Abstract
Animal behaviour often comprises spatially separated sub-reactions and even ciliated larvae are able to coordinate sub-reactions of complex behaviours (metamorphosis, feeding). How these sub-reactions are coordinated is currently not well understood. Neuropeptides are potential candidates for triggering larval behaviour. However, although their immunoreactivity has been widely analysed, their function in trochozoan larvae has only been studied for a few cases. Here, we investigate the role of neuropeptides in the defence behaviour of brachiopod larvae. When mechanically disturbed, the planktonic larvae of Terebratalia transversa protrude their stiff chaetae and sink down slowly. We identified endogenous FLRFamide-type neuropeptides (AFLRFamide and DFLRFamide) in T. transversa larvae and show that the protrusion of the chaetae as well as the sinking reaction can both be induced by each of these peptides. This also correlates with the presence of FLRFamidergic neurons in the apical lobe and adjacent to the trunk musculature. We deorphanized the AFLRFamide/DFLRFamide receptor and detected its expression in the same tissues. Furthermore, the ability of native and modified FLRFamide-type peptides to activate this receptor was found to correspond with their ability to trigger behavioural responses. Our results show how FLRFamide-type neuropeptides can induce two coherent sub-reactions in a larva with a simple nervous system.
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Affiliation(s)
- Daniel Thiel
- Sars International Centre for Marine Molecular Biology, University of Bergen, Thormøhlensgate 55, 5006 Bergen, Norway
| | - Philipp Bauknecht
- Max Planck Institute for Developmental Biology, Spemannstraße 35, 72076 Tübingen, Germany
| | - Gáspár Jékely
- Max Planck Institute for Developmental Biology, Spemannstraße 35, 72076 Tübingen, Germany
| | - Andreas Hejnol
- Sars International Centre for Marine Molecular Biology, University of Bergen, Thormøhlensgate 55, 5006 Bergen, Norway
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9
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Achim K, Eling N, Vergara HM, Bertucci PY, Musser J, Vopalensky P, Brunet T, Collier P, Benes V, Marioni JC, Arendt D. Whole-Body Single-Cell Sequencing Reveals Transcriptional Domains in the Annelid Larval Body. Mol Biol Evol 2018; 35:1047-1062. [PMID: 29373712 PMCID: PMC5913682 DOI: 10.1093/molbev/msx336] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Animal bodies comprise diverse arrays of cells. To characterize cellular identities across an entire body, we have compared the transcriptomes of single cells randomly picked from dissociated whole larvae of the marine annelid Platynereis dumerilii. We identify five transcriptionally distinct groups of differentiated cells, each expressing a unique set of transcription factors and effector genes that implement cellular phenotypes. Spatial mapping of cells into a cellular expression atlas, and wholemount in situ hybridization of group-specific genes reveals spatially coherent transcriptional domains in the larval body, comprising, for example, apical sensory-neurosecretory cells versus neural/epidermal surface cells. These domains represent new, basic subdivisions of the annelid body based entirely on differential gene expression, and are composed of multiple, transcriptionally similar cell types. They do not represent clonal domains, as revealed by developmental lineage analysis. We propose that the transcriptional domains that subdivide the annelid larval body represent families of related cell types that have arisen by evolutionary diversification. Their possible evolutionary conservation makes them a promising tool for evo-devo research.
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Affiliation(s)
- Kaia Achim
- Developmental Biology Unit, European Molecular Biology Laboratory, Heidelberg, Germany
| | - Nils Eling
- EMBL-European Bioinformatics Institute (EMBL-EBI), Wellcome Genome Campus, Cambridge, United Kingdom
- Cancer Research UK Cambridge Institute, University of Cambridge, Cambridge, United Kingdom
| | | | - Paola Yanina Bertucci
- Developmental Biology Unit, European Molecular Biology Laboratory, Heidelberg, Germany
| | - Jacob Musser
- Developmental Biology Unit, European Molecular Biology Laboratory, Heidelberg, Germany
| | - Pavel Vopalensky
- Developmental Biology Unit, European Molecular Biology Laboratory, Heidelberg, Germany
| | - Thibaut Brunet
- Developmental Biology Unit, European Molecular Biology Laboratory, Heidelberg, Germany
| | - Paul Collier
- Genomics Core Facility, European Molecular Biology Laboratory, Heidelberg, Germany
| | - Vladimir Benes
- Genomics Core Facility, European Molecular Biology Laboratory, Heidelberg, Germany
| | - John C Marioni
- EMBL-European Bioinformatics Institute (EMBL-EBI), Wellcome Genome Campus, Cambridge, United Kingdom
- Cancer Research UK Cambridge Institute, University of Cambridge, Cambridge, United Kingdom
- Wellcome Trust Sanger Institute, Wellcome Genome Campus, Cambridge, United Kingdom
| | - Detlev Arendt
- Developmental Biology Unit, European Molecular Biology Laboratory, Heidelberg, Germany
- Centre for Organismal Studies, University of Heidelberg, Heidelberg, Germany
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10
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Handberg-Thorsager M, Gutierrez-Mazariegos J, Arold ST, Kumar Nadendla E, Bertucci PY, Germain P, Tomançak P, Pierzchalski K, Jones JW, Albalat R, Kane MA, Bourguet W, Laudet V, Arendt D, Schubert M. The ancestral retinoic acid receptor was a low-affinity sensor triggering neuronal differentiation. SCIENCE ADVANCES 2018; 4:eaao1261. [PMID: 29492455 PMCID: PMC5821490 DOI: 10.1126/sciadv.aao1261] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/19/2017] [Accepted: 01/10/2018] [Indexed: 06/02/2023]
Abstract
Retinoic acid (RA) is an important intercellular signaling molecule in vertebrate development, with a well-established role in the regulation of hox genes during hindbrain patterning and in neurogenesis. However, the evolutionary origin of the RA signaling pathway remains elusive. To elucidate the evolution of the RA signaling system, we characterized RA metabolism and signaling in the marine annelid Platynereis dumerilii, a powerful model for evolution, development, and neurobiology. Binding assays and crystal structure analyses show that the annelid retinoic acid receptor (RAR) binds RA and activates transcription just as vertebrate RARs, yet with a different ligand-binding pocket and lower binding affinity, suggesting a permissive rather than instructive role of RA signaling. RAR knockdown and RA treatment of swimming annelid larvae further reveal that the RA signal is locally received in the medial neuroectoderm, where it controls neurogenesis and axon outgrowth, whereas the spatial colinear hox gene expression in the neuroectoderm remains unaffected. These findings suggest that one early role of the new RAR in bilaterian evolution was to control the spatially restricted onset of motor and interneuron differentiation in the developing ventral nerve cord and to indicate that the regulation of hox-controlled anterior-posterior patterning arose only at the base of the chordates, concomitant with a high-affinity RAR needed for the interpretation of a complex RA gradient.
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Affiliation(s)
- Mette Handberg-Thorsager
- Developmental Biology Unit, European Molecular Biology Laboratory, Meyerhofstrasse 1, 69012 Heidelberg, Germany
| | - Juliana Gutierrez-Mazariegos
- Molecular Zoology Team, Institut de Génomique Fonctionnelle de Lyon, Université de Lyon, Université Lyon 1, CNRS, Institut National de la Recherche Agronomique, Ecole Normale Supérieure de Lyon, 46 Allée d’Italie, 69364 Lyon Cedex 07, France
| | - Stefan T. Arold
- King Abdullah University of Science and Technology, Center for Computational Bioscience Research, Division of Biological and Environmental Sciences and Engineering, Thuwal 23955-6900, Saudi Arabia
| | - Eswar Kumar Nadendla
- Centre de Biochimie Structurale, Inserm, CNRS, Université de Montpellier, 29 Rue de Navacelles, 34090 Montpellier, France
| | - Paola Y. Bertucci
- Developmental Biology Unit, European Molecular Biology Laboratory, Meyerhofstrasse 1, 69012 Heidelberg, Germany
| | - Pierre Germain
- Centre de Biochimie Structurale, Inserm, CNRS, Université de Montpellier, 29 Rue de Navacelles, 34090 Montpellier, France
| | - Pavel Tomançak
- Max Planck Institute of Molecular Cell Biology and Genetics, Pfotenhauerstrasse 108, 01307 Dresden, Germany
| | - Keely Pierzchalski
- Department of Pharmaceutical Sciences, School of Pharmacy, University of Maryland, 20 North Pine Street, Baltimore, MD 21201, USA
| | - Jace W. Jones
- Department of Pharmaceutical Sciences, School of Pharmacy, University of Maryland, 20 North Pine Street, Baltimore, MD 21201, USA
| | - Ricard Albalat
- Departament de Genètica, Microbiologia i Estadística, Institut de Recerca de la Biodiversitat (IRBio), Facultat de Biologia, Universitat de Barcelona, Avinguda Diagonal 643, 08028 Barcelona, Spain
| | - Maureen A. Kane
- Department of Pharmaceutical Sciences, School of Pharmacy, University of Maryland, 20 North Pine Street, Baltimore, MD 21201, USA
| | - William Bourguet
- Centre de Biochimie Structurale, Inserm, CNRS, Université de Montpellier, 29 Rue de Navacelles, 34090 Montpellier, France
| | - Vincent Laudet
- Molecular Zoology Team, Institut de Génomique Fonctionnelle de Lyon, Université de Lyon, Université Lyon 1, CNRS, Institut National de la Recherche Agronomique, Ecole Normale Supérieure de Lyon, 46 Allée d’Italie, 69364 Lyon Cedex 07, France
| | - Detlev Arendt
- Developmental Biology Unit, European Molecular Biology Laboratory, Meyerhofstrasse 1, 69012 Heidelberg, Germany
- Centre for Organismal Studies, University of Heidelberg, Im Neuenheimer Feld 230, 69120 Heidelberg, Germany
| | - Michael Schubert
- Sorbonne Universités, Université Pierre et Marie Curie (UPMC) Université Paris 06, CNRS, Laboratoire de Biologie du Développement de Villefranche-sur-Mer, Observatoire Océanologique de Villefranche-sur-Mer, 181 Chemin du Lazaret, 06230 Villefranche-sur-Mer, France
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11
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Gazave E, Lemaître QIB, Balavoine G. The Notch pathway in the annelid Platynereis: insights into chaetogenesis and neurogenesis processes. Open Biol 2017; 7:rsob.160242. [PMID: 28148821 PMCID: PMC5356439 DOI: 10.1098/rsob.160242] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2016] [Accepted: 01/03/2017] [Indexed: 01/13/2023] Open
Abstract
Notch is a key signalling pathway playing multiple and varied functions during development. Notch regulates the selection of cells with a neurogenic fate and maintains a pool of yet uncommitted precursors through lateral inhibition, both in insects and in vertebrates. Here, we explore the functions of Notch in the annelid Platynereis dumerilii (Lophotrochozoa). Conserved components of the pathway are identified and a scenario for their evolution in metazoans is proposed. Unexpectedly, neither Notch nor its ligands are expressed in the neurogenic epithelia of the larva at the time when massive neurogenesis begins. Using chemical inhibitors and neural markers, we demonstrate that Notch plays no major role in the general neurogenesis of larvae. Instead, we find Notch components expressed in nascent chaetal sacs, the organs that produce the annelid bristles. Impairing Notch signalling induces defects in chaetal sac formation, abnormalities in chaetae producing cells and a change of identity of chaeta growth accessory cells. This is the first bilaterian species in which the early neurogenesis processes appear to occur without a major involvement of the Notch pathway. Instead, Notch is co-opted to pattern annelid-specific organs, likely through a lateral inhibition process. These features reinforce the view that Notch signalling has been recruited multiple times in evolution due to its remarkable ‘toolkit’ nature.
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Affiliation(s)
- Eve Gazave
- Institut Jacques Monod, CNRS, UMR 7592, Univ Paris Diderot, Sorbonne Paris Cité, 75205 Paris, France
| | - Quentin I B Lemaître
- Institut Jacques Monod, CNRS, UMR 7592, Univ Paris Diderot, Sorbonne Paris Cité, 75205 Paris, France
| | - Guillaume Balavoine
- Institut Jacques Monod, CNRS, UMR 7592, Univ Paris Diderot, Sorbonne Paris Cité, 75205 Paris, France
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12
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M1 ipRGCs Influence Visual Function through Retrograde Signaling in the Retina. J Neurosci 2017; 36:7184-97. [PMID: 27383593 DOI: 10.1523/jneurosci.3500-15.2016] [Citation(s) in RCA: 81] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2015] [Accepted: 05/26/2016] [Indexed: 12/23/2022] Open
Abstract
UNLABELLED Melanopsin-expressing intrinsically photosensitive retinal ganglion cells (ipRGCs, with five subtypes named M1-M5) are a unique subclass of RGCs with axons that project directly to many brain nuclei involved in non-image-forming functions such as circadian photoentrainment and the pupillary light reflex. Recent evidence suggests that melanopsin-based signals also influence image-forming visual function, including light adaptation, but the mechanisms involved are unclear. Intriguingly, a small population of M1 ipRGCs have intraretinal axon collaterals that project toward the outer retina. Using genetic mouse models, we provide three lines of evidence showing that these axon collaterals make connections with upstream dopaminergic amacrine cells (DACs): (1) ipRGC signaling to DACs is blocked by tetrodotoxin both in vitro and in vivo, indicating that ipRGC-to-DAC transmission requires voltage-gated Na(+) channels; (2) this transmission is partly dependent on N-type Ca(2+) channels, which are possibly expressed in the axon collateral terminals of ipRGCs; and (3) fluorescence microscopy reveals that ipRGC axon collaterals make putative presynaptic contact with DACs. We further demonstrate that elimination of M1 ipRGCs attenuates light adaptation, as evidenced by an impaired electroretinogram b-wave from cones, whereas a dopamine receptor agonist can potentiate the cone-driven b-wave of retinas lacking M1 ipRGCs. Together, the results strongly suggest that ipRGCs transmit luminance signals retrogradely to the outer retina through the dopaminergic system and in turn influence retinal light adaptation. SIGNIFICANCE STATEMENT Melanopsin-expressing intrinsically photosensitive retinal ganglion cells (ipRGCs) comprise a third class of retinal photoreceptors that are known to mediate physiological responses such as circadian photoentrainment. However, investigation into whether and how ipRGCs contribute to vision has just begun. Here, we provide convergent anatomical and physiological evidence that axon collaterals of ipRGCs constitute a centrifugal pathway to DACs, conveying melanopsin-based signals from the innermost retina to the outer retina. We further demonstrate that retrograde signals likely influence visual processing because elimination of axon collateral-bearing ipRGCs impairs light adaptation by limiting dopamine-dependent facilitation of the cone pathway. Our findings strongly support the hypothesis that retrograde melanopsin-based signaling influences visual function locally within the retina, a notion that refutes the dogma that RGCs only provide physiological signals to the brain.
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Vellutini BC, Martín-Durán JM, Hejnol A. Cleavage modification did not alter blastomere fates during bryozoan evolution. BMC Biol 2017; 15:33. [PMID: 28454545 PMCID: PMC5408385 DOI: 10.1186/s12915-017-0371-9] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2017] [Accepted: 04/04/2017] [Indexed: 12/22/2022] Open
Abstract
BACKGROUND Stereotypic cleavage patterns play a crucial role in cell fate determination by precisely positioning early embryonic blastomeres. Although misplaced cell divisions can alter blastomere fates and cause embryonic defects, cleavage patterns have been modified several times during animal evolution. However, it remains unclear how evolutionary changes in cleavage impact the specification of blastomere fates. Here, we analyze the transition from spiral cleavage - a stereotypic pattern remarkably conserved in many protostomes - to a biradial cleavage pattern, which occurred during the evolution of bryozoans. RESULTS Using 3D-live imaging time-lapse microscopy (4D-microscopy), we characterize the cell lineage, MAPK signaling, and the expression of 16 developmental genes in the bryozoan Membranipora membranacea. We found that the molecular identity and the fates of early bryozoan blastomeres are similar to the putative homologous blastomeres in spiral-cleaving embryos. CONCLUSIONS Our work suggests that bryozoans have retained traits of spiral development, such as the early embryonic fate map, despite the evolution of a novel cleavage geometry. These findings provide additional support that stereotypic cleavage patterns can be modified during evolution without major changes to the molecular identity and fate of embryonic blastomeres.
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Affiliation(s)
- Bruno C Vellutini
- Sars International Centre for Marine Molecular Biology, University of Bergen, Thormøhlensgate 55, 5006, Bergen, Norway
| | - José M Martín-Durán
- Sars International Centre for Marine Molecular Biology, University of Bergen, Thormøhlensgate 55, 5006, Bergen, Norway
| | - Andreas Hejnol
- Sars International Centre for Marine Molecular Biology, University of Bergen, Thormøhlensgate 55, 5006, Bergen, Norway.
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Scherholz M, Redl E, Wollesen T, de Oliveira AL, Todt C, Wanninger A. Ancestral and novel roles of Pax family genes in mollusks. BMC Evol Biol 2017; 17:81. [PMID: 28302062 PMCID: PMC5356317 DOI: 10.1186/s12862-017-0919-x] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2016] [Accepted: 02/18/2017] [Indexed: 01/31/2023] Open
Abstract
Background Pax genes are transcription factors with significant roles in cell fate specification and tissue differentiation during animal ontogeny. Most information on their tempo-spatial mode of expression is available from well-studied model organisms where the Pax-subfamilies Pax2/5/8, Pax6, and Paxα/β are mainly involved in the development of the central nervous system (CNS), the eyes, and other sensory organs. In certain taxa, Pax2/5/8 seems to be additionally involved in the development of excretion organs. Data on expression patterns in lophotrochozoans, and in particular in mollusks, are very scarce for all the above-mentioned Pax-subfamilies, which hampers reconstruction of their putative ancestral roles in bilaterian animals. Thus, we studied the developmental expression of Pax2/5/8, Pax6, and the lophotrochozoan-specific Paxβ in the worm-shaped mollusk Wirenia argentea, a member of Aplacophora that together with Polyplacophora forms the Aculifera, the proposed sister taxon to all primarily single-shelled mollusks (Conchifera). Results All investigated Pax genes are expressed in the developing cerebral ganglia and in the ventral nerve cords, but not in the lateral nerve cords of the tetraneural nervous system. Additionally, Pax2/5/8 is expressed in epidermal spicule-secreting or associated cells of the larval trunk and in the region of the developing protonephridia. We found no indication for an involvement of the investigated Pax genes in the development of larval or adult sensory organs of Wirenia argentea. Conclusions Pax2/5/8 seems to have a conserved role in the development of the CNS, whereas expression in the spicule-secreting tissues of aplacophorans and polyplacophorans suggests co-option in aculiferan skeletogenesis. The Pax6 expression pattern in Aculifera largely resembles the common bilaterian expression during CNS development. All data available on Paxβ expression argue for a common role in lophotrochozoan neurogenesis. Electronic supplementary material The online version of this article (doi:10.1186/s12862-017-0919-x) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Maik Scherholz
- Department of Integrative Zoology, Faculty of Life Sciences, University of Vienna, Althanstraße 14, 1090, Vienna, Austria
| | - Emanuel Redl
- Department of Integrative Zoology, Faculty of Life Sciences, University of Vienna, Althanstraße 14, 1090, Vienna, Austria
| | - Tim Wollesen
- Department of Integrative Zoology, Faculty of Life Sciences, University of Vienna, Althanstraße 14, 1090, Vienna, Austria
| | - André Luiz de Oliveira
- Department of Integrative Zoology, Faculty of Life Sciences, University of Vienna, Althanstraße 14, 1090, Vienna, Austria
| | - Christiane Todt
- University Museum of Bergen, University of Bergen, Allégaten 41, 5007, Bergen, Norway
| | - Andreas Wanninger
- Department of Integrative Zoology, Faculty of Life Sciences, University of Vienna, Althanstraße 14, 1090, Vienna, Austria.
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Redl E, Scherholz M, Wollesen T, Todt C, Wanninger A. Cell Proliferation Pattern and Twist Expression in an Aplacophoran Mollusk Argue Against Segmented Ancestry of Mollusca. JOURNAL OF EXPERIMENTAL ZOOLOGY PART B-MOLECULAR AND DEVELOPMENTAL EVOLUTION 2016; 326:422-436. [PMID: 27966274 PMCID: PMC5299467 DOI: 10.1002/jez.b.22714] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/08/2016] [Revised: 10/28/2016] [Accepted: 11/02/2016] [Indexed: 01/12/2023]
Abstract
The study of aplacophoran mollusks (i.e., Solenogastres or Neomeniomorpha and Caudofoveata or Chaetodermomorpha) has traditionally been regarded as crucial for reconstructing the morphology of the last common ancestor of the Mollusca. Since their proposed close relatives, the Polyplacophora, show a distinct seriality in certain organ systems, the aplacophorans are also in the focus of attention with regard to the question of a potential segmented ancestry of mollusks. To contribute to this question, we investigated cell proliferation patterns and the expression of the twist ortholog during larval development in solenogasters. In advanced to late larvae, during the outgrowth of the trunk, a pair of longitudinal bands of proliferating cells is found subepithelially in a lateral to ventrolateral position. These bands elongate during subsequent development as the trunk grows longer. Likewise, expression of twist occurs in two laterally positioned, subepithelial longitudinal stripes in advanced larvae. Both, the pattern of proliferating cells and the expression domain of twist demonstrate the existence of extensive and long‐lived mesodermal bands in a worm‐shaped aculiferan, a situation which is similar to annelids but in stark contrast to conchiferans, where the mesodermal bands are usually rudimentary and ephemeral. Yet, in contrast to annelids, neither the bands of proliferating cells nor the twist expression domain show a separation into distinct serial subunits, which clearly argues against a segmented ancestry of mollusks. Furthermore, the lack of twist expression during the development of the ventromedian muscle argues against homology of a ventromedian longitudinal muscle in protostomes with the notochord of chordates.
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Affiliation(s)
- Emanuel Redl
- Faculty of Life Sciences, Department of Integrative Zoology, University of Vienna, Vienna, Austria
| | - Maik Scherholz
- Faculty of Life Sciences, Department of Integrative Zoology, University of Vienna, Vienna, Austria
| | - Tim Wollesen
- Faculty of Life Sciences, Department of Integrative Zoology, University of Vienna, Vienna, Austria
| | - Christiane Todt
- University Museum, The Natural History Collections, University of Bergen, Bergen, Norway
| | - Andreas Wanninger
- Faculty of Life Sciences, Department of Integrative Zoology, University of Vienna, Vienna, Austria
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Effect of Extremely Low Frequency Electromagnetic Field on MAP2 and Nestin Gene Expression of Hair Follicle Dermal Papilla Cells. Int J Artif Organs 2016; 39:294-9. [DOI: 10.5301/ijao.5000512] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/05/2016] [Indexed: 12/19/2022]
Abstract
Introduction In recent years, the extremely low frequency electromagnetic field (ELF-EMF) has attracted a great deal of scientific interest. The ELF-EMF signal is able to control ion transport across ion channels and therefore induce cell differentiation. Aim The purpose of this study was to investigate the effect of ELF-EMF (50 Hz, 1 mT) on MAP2 and Nestin gene expression of dermal papilla mesenchymal cells (DPCs). Methods In order to examine the effect of chemical and electromagnetic factors on gene expression, 4 experimental groups, namely chemical (cell exposure to chemical signals), EMF (exposing cells to ELF-EMF), chemical-EMF (subjecting cells to chemical signals and ELF-EMF) and control (with no treatment) groups, were prepared, treated for 5 days, and studied. To assess the effect of extended test time on the expression of neural differentiation markers (Nestin and MAP2), an EMF group was prepared and treated for a period of 14 consecutive days. The beneficial role of EMF in inducing neural differentiation was shown by real-time PCR analysis. Results The higher expression of MAP2 after 14 days compared to that after 5 days and decrease of cell proliferation on days 5 to 20 were indicative of the positive effect of extending treatment time on neural differentiation by evaluation of gene expression in EMF group.
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17
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Detection and signal amplification in zebrafish RNA FISH. Methods 2016; 98:50-59. [PMID: 26821229 DOI: 10.1016/j.ymeth.2016.01.012] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2015] [Revised: 01/18/2016] [Accepted: 01/25/2016] [Indexed: 11/23/2022] Open
Abstract
In situ hybridization (ISH) has become an invaluable tool for the detection of RNA in cells, tissues and organisms. Due to improvements in target and signal amplification and in probe design remarkable progress has been made concerning sensitivity, specificity and resolution of chromogenic and fluorescent ISH (FISH). These advancements allow for exquisite cellular and sub-cellular resolution and for detecting multiple RNA species at a time by multiplexing. In zebrafish (F)ISH non-enzymatic and enzymatic amplification systems have been employed to obtain enhanced signal intensities and signal-to-noise ratios. These amplification strategies include branched DNA-based RNAscope and in situ hybridization chain reaction (HCR) techniques, as well as alkaline phosphatase (AP)- and horseradish peroxidase (PO)-based immunoassays. For practical application, we provide proven multiplex FISH protocols for AP- and PO-based visualization of mRNAs at high resolution. The protocols take advantage of optimized tyramide signal amplification (TSA) conditions of the PO assay and long-lasting high signal-to-noise ratio of the AP reaction, thereby enabling detection of less abundant transcripts.
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Wollesen T, Rodríguez Monje SV, Todt C, Degnan BM, Wanninger A. Ancestral role of Pax2/5/8 in molluscan brain and multimodal sensory system development. BMC Evol Biol 2015; 15:231. [PMID: 26511716 PMCID: PMC4625944 DOI: 10.1186/s12862-015-0505-z] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2015] [Accepted: 10/01/2015] [Indexed: 02/07/2023] Open
Abstract
BACKGROUND Mollusks represent the largest lophotrochozoan phylum and exhibit highly diverse body plans. Previous studies have demonstrated that transcription factors such as Pax genes play important roles during their development. Accordingly, in ecdysozoan and vertebrate model organisms, orthologs of Pax2/5/8 are among others involved in the formation of the midbrain/hindbrain boundary, the auditory/geosensory organ systems, and the excretory system. METHODS Pax2/5/8 expression was investigated by in situ hybridization during the development of representatives of the two major molluscan subclades, Aculifera and Conchifera. RESULTS Compared to the investigated polyplacophoran and bivalve species that lack larval statocysts as geosensory organs and elaborate central nervous systems (CNS), cephalopods possess highly centralized brains and statocysts. Pax2/5/8 is expressed in regions where sensory cells develop subsequently during ontogenesis. Expression domains include esthetes and the ampullary system in polyplacophorans as well as the eyes of cephalopods. No Pax2/5/8 expression was observed in the less centralized CNS of bivalve, polyplacophoran, and gastropod embryos, thus arguing for a loss of Pax2/5/8 involvement in CNS development in these lineages. In contrast, Pax2/5/8 is expressed among others in brain lobes along the trajectory of the esophagus that divides the cephalopod brain. CONCLUSIONS Our results, along with those on Otx- and Hox-gene expression, demonstrate that the cephalopod condition is similar to that in mouse and fruit fly, with Otx being expressed in the anterior-most brain region (except for the vertical lobe) and a Pax2/5/8 expression domain separating the Otx-domain from a Hox-gene expressing posterior brain region. Thus, Pax2/5/8 appears to have been recruited independently into regionalization of non-homologous complex brains of organisms as different as squid, fruit fly, and mouse. In addition, Pax2/5/8 is expressed in multimodal sensory systems in mollusks such as the esthetes and the ampullary system of polyplacophorans as well as the eyes of cephalopods. Pax2/5/8-expressing cells are present in regions where the future sensory cells such as the polyplacophoran esthetes are situated and hence Pax2/5/8 expression probably predates sensory cell development during ontogeny. In mollusks, Pax2/5/8 is only expressed in derivatives of the ectoderm and hence an ancestral role in molluscan ectoderm differentiation is inferred.
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Affiliation(s)
- Tim Wollesen
- Department of Integrative Zoology, Faculty of Sciences, University of Vienna, 1090, Vienna, Austria.
| | | | - Christiane Todt
- University Museum of Bergen, University of Bergen, Allégaten 41, 5007, Bergen, Norway.
| | - Bernard M Degnan
- School of Biological Sciences, The University of Queensland, Brisbane, QLD, 4072, Australia.
| | - Andreas Wanninger
- Department of Integrative Zoology, Faculty of Sciences, University of Vienna, 1090, Vienna, Austria.
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Gühmann M, Jia H, Randel N, Verasztó C, Bezares-Calderón LA, Michiels NK, Yokoyama S, Jékely G. Spectral Tuning of Phototaxis by a Go-Opsin in the Rhabdomeric Eyes of Platynereis. Curr Biol 2015; 25:2265-71. [PMID: 26255845 DOI: 10.1016/j.cub.2015.07.017] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2015] [Revised: 05/26/2015] [Accepted: 07/07/2015] [Indexed: 11/30/2022]
Abstract
Phototaxis is characteristic of the pelagic larval stage of most bottom-dwelling marine invertebrates. Larval phototaxis is mediated by simple eyes that can express various types of light-sensitive G-protein-coupled receptors known as opsins. Since opsins diversified early during metazoan evolution in the marine environment, understanding underwater light detection could elucidate this diversification. Opsins have been classified into three major families, the r-opsins, the c-opsins, and the Go/RGR opsins, a family uniting Go-opsins, retinochromes, RGR opsins, and neuropsins. The Go-opsins form an ancient and poorly characterized group retained only in marine invertebrate genomes. Here, we characterize a Go-opsin from the marine annelid Platynereis dumerilii. We found Go-opsin1 coexpressed with two r-opsins in depolarizing rhabdomeric photoreceptor cells in the pigmented eyes of Platynereis larvae. We purified recombinant Go-opsin1 and found that it absorbs in the blue-cyan range of the light spectrum. To characterize the function of Go-opsin1, we generated a Go-opsin1 knockout Platynereis line by zinc-finger-nuclease-mediated genome engineering. Go-opsin1 knockout larvae were phototactic but showed reduced efficiency of phototaxis to wavelengths matching the in vitro Go-opsin1 spectrum. Our results highlight spectral tuning of phototaxis as a potential mechanism contributing to opsin diversity.
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Affiliation(s)
- Martin Gühmann
- Max Planck Institute for Developmental Biology, Spemannstraße 35, 72076 Tübingen, Germany
| | - Huiyong Jia
- Department of Biology, Emory University, 1510 Clifton Road, Atlanta, GA 30322, USA
| | - Nadine Randel
- Max Planck Institute for Developmental Biology, Spemannstraße 35, 72076 Tübingen, Germany
| | - Csaba Verasztó
- Max Planck Institute for Developmental Biology, Spemannstraße 35, 72076 Tübingen, Germany
| | | | - Nico K Michiels
- Department of Biology, University of Tübingen, 72076 Tübingen, Germany
| | - Shozo Yokoyama
- Department of Biology, Emory University, 1510 Clifton Road, Atlanta, GA 30322, USA
| | - Gáspár Jékely
- Max Planck Institute for Developmental Biology, Spemannstraße 35, 72076 Tübingen, Germany.
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20
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Fritsch M, Wollesen T, de Oliveira AL, Wanninger A. Unexpected co-linearity of Hox gene expression in an aculiferan mollusk. BMC Evol Biol 2015; 15:151. [PMID: 26243538 PMCID: PMC4524011 DOI: 10.1186/s12862-015-0414-1] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2015] [Accepted: 06/08/2015] [Indexed: 01/12/2023] Open
Abstract
BACKGROUND Mollusca is an extremely diverse animal phylum that includes the aculiferans (worm-like aplacophorans and eight-shelled polyplacophorans) and their sister group, the conchiferans, comprising monoplacophorans, bivalves (clams, mussels), gastropods (snails, slugs), scaphopods (tusk shells) and cephalopods (squids, octopuses). Studies on mollusks have revealed an overall number of 11 Hox genes in seven out of eight molluscan "class"-level taxa, but expression data of key developmental regulators such as homeotic genes are only available for three gastropod and two cephalopod species. These show that Hox genes are involved in the formation of specific features including shell, foot, funnel or tentacles and not in antero-posterior body plan patterning as in most other bilaterian animals. The role of Hox genes in non-conchiferan (i.e., aculiferan) mollusks remains entirely unknown. RESULTS Here we present the first data on the expression of seven Hox genes in apolyplacophoran mollusk, Acanthochitona crinita. In A. crinita the Hox genes Acr-Hox1-5, Hox7 and Post2 are expressed in a co-linear pattern along the antero-posterior axis, but not in molluscan-specific features such as the shell or the foot. The expression pattern is restricted to the post-trochal region and the transcripts are present in ecto-, endo- and mesodermal cell layers. Contrary to the situation in gastropods and cephalopods, we did neither find Hox gene expression in distinct neural subsets of A. crinita, nor in its developing shell plates. CONCLUSIONS Our analysis and comparison with other lophotrochozoans indicate that the basal role of Hox genes is in antero-posterior axis patterning in mollusks, similar to the vast majority of bilaterian animals, and that this role has been conserved in polyplacophorans, while co-option into patterning of evolutionary novelties emerged either at the base of Conchifera or independently in gastropods and cephalopods. These morphological innovations most likely contributed to the evolutionary success of its representatives, as exemplified by, e.g., the wide ecological range and species richness of gastropods.
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Affiliation(s)
- M Fritsch
- Department of Integrative Zoology, Faculty of Life Sciences, University of Vienna, Althanstrasse 14, 1090, Vienna, Austria.
| | - T Wollesen
- Department of Integrative Zoology, Faculty of Life Sciences, University of Vienna, Althanstrasse 14, 1090, Vienna, Austria.
| | - A L de Oliveira
- Department of Integrative Zoology, Faculty of Life Sciences, University of Vienna, Althanstrasse 14, 1090, Vienna, Austria.
| | - A Wanninger
- Department of Integrative Zoology, Faculty of Life Sciences, University of Vienna, Althanstrasse 14, 1090, Vienna, Austria.
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Wanninger A. Morphology is dead – long live morphology! Integrating MorphoEvoDevo into molecular EvoDevo and phylogenomics. Front Ecol Evol 2015. [DOI: 10.3389/fevo.2015.00054] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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Tosches MA, Bucher D, Vopalensky P, Arendt D. Melatonin signaling controls circadian swimming behavior in marine zooplankton. Cell 2015; 159:46-57. [PMID: 25259919 PMCID: PMC4182423 DOI: 10.1016/j.cell.2014.07.042] [Citation(s) in RCA: 91] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2014] [Revised: 06/07/2014] [Accepted: 07/25/2014] [Indexed: 12/29/2022]
Abstract
Melatonin, the "hormone of darkness," is a key regulator of vertebrate circadian physiology and behavior. Despite its ubiquitous presence in Metazoa, the function of melatonin signaling outside vertebrates is poorly understood. Here, we investigate the effect of melatonin signaling on circadian swimming behavior in a zooplankton model, the marine annelid Platynereis dumerilii. We find that melatonin is produced in brain photoreceptors with a vertebrate-type opsin-based phototransduction cascade and a light-entrained clock. Melatonin released at night induces rhythmic burst firing of cholinergic neurons that innervate locomotor-ciliated cells. This establishes a nocturnal behavioral state by modulating the length and the frequency of ciliary arrests. Based on our findings, we propose that melatonin signaling plays a role in the circadian control of ciliary swimming to adjust the vertical position of zooplankton in response to ambient light.
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Affiliation(s)
- Maria Antonietta Tosches
- European Molecular Biology Laboratory, Developmental Biology Unit, Meyerhofstrasse 1, 69117 Heidelberg, Germany.
| | - Daniel Bucher
- European Molecular Biology Laboratory, Developmental Biology Unit, Meyerhofstrasse 1, 69117 Heidelberg, Germany; Centre for Organismal Studies (COS), University of Heidelberg, 69120 Heidelberg, Germany
| | - Pavel Vopalensky
- European Molecular Biology Laboratory, Developmental Biology Unit, Meyerhofstrasse 1, 69117 Heidelberg, Germany
| | - Detlev Arendt
- European Molecular Biology Laboratory, Developmental Biology Unit, Meyerhofstrasse 1, 69117 Heidelberg, Germany; Centre for Organismal Studies (COS), University of Heidelberg, 69120 Heidelberg, Germany.
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High-throughput spatial mapping of single-cell RNA-seq data to tissue of origin. Nat Biotechnol 2015; 33:503-9. [PMID: 25867922 DOI: 10.1038/nbt.3209] [Citation(s) in RCA: 278] [Impact Index Per Article: 30.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2014] [Accepted: 03/13/2015] [Indexed: 01/12/2023]
Abstract
Understanding cell type identity in a multicellular organism requires the integration of gene expression profiles from individual cells with their spatial location in a particular tissue. Current technologies allow whole-transcriptome sequencing of spatially identified cells but lack the throughput needed to characterize complex tissues. Here we present a high-throughput method to identify the spatial origin of cells assayed by single-cell RNA-sequencing within a tissue of interest. Our approach is based on comparing complete, specificity-weighted mRNA profiles of a cell with positional gene expression profiles derived from a gene expression atlas. We show that this method allocates cells to precise locations in the brain of the marine annelid Platynereis dumerilii with a success rate of 81%. Our method is applicable to any system that has a reference gene expression database of sufficiently high resolution.
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Zantke J, Bannister S, Rajan VBV, Raible F, Tessmar-Raible K. Genetic and genomic tools for the marine annelid Platynereis dumerilii. Genetics 2014; 197:19-31. [PMID: 24807110 PMCID: PMC4012478 DOI: 10.1534/genetics.112.148254] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2013] [Accepted: 02/17/2014] [Indexed: 01/27/2023] Open
Abstract
The bristle worm Platynereis dumerilii displays many interesting biological characteristics. These include its reproductive timing, which is synchronized to the moon phase, its regenerative capacity that is hormonally controlled, and a slow rate of evolution, which permits analyses of ancestral genes and cell types. As a marine annelid, Platynereis is also representative of the marine ecosystem, as well as one of the three large animal subphyla, the Lophotrochozoa. Here, we provide an overview of the molecular resources, functional techniques, and behavioral assays that have recently been established for the bristle worm. This combination of tools now places Platynereis in an excellent position to advance research at the frontiers of neurobiology, chronobiology, evo-devo, and marine biology.
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Affiliation(s)
- Juliane Zantke
- Max F. Perutz Laboratories
- Research Platform Marine Rhythms of Life, University of Vienna 1030 Vienna, Austria
| | - Stephanie Bannister
- Max F. Perutz Laboratories
- Research Platform Marine Rhythms of Life, University of Vienna 1030 Vienna, Austria
| | - Vinoth Babu Veedin Rajan
- Max F. Perutz Laboratories
- Research Platform Marine Rhythms of Life, University of Vienna 1030 Vienna, Austria
| | - Florian Raible
- Max F. Perutz Laboratories
- Research Platform Marine Rhythms of Life, University of Vienna 1030 Vienna, Austria
| | - Kristin Tessmar-Raible
- Max F. Perutz Laboratories
- Research Platform Marine Rhythms of Life, University of Vienna 1030 Vienna, Austria
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Marlow H, Tosches MA, Tomer R, Steinmetz PR, Lauri A, Larsson T, Arendt D. Larval body patterning and apical organs are conserved in animal evolution. BMC Biol 2014; 12:7. [PMID: 24476105 PMCID: PMC3939940 DOI: 10.1186/1741-7007-12-7] [Citation(s) in RCA: 127] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2013] [Accepted: 01/24/2014] [Indexed: 12/31/2022] Open
Abstract
Background Planktonic ciliated larvae are characteristic for the life cycle of marine invertebrates. Their most prominent feature is the apical organ harboring sensory cells and neurons of largely undetermined function. An elucidation of the relationships between various forms of primary larvae and apical organs is key to understanding the evolution of animal life cycles. These relationships have remained enigmatic due to the scarcity of comparative molecular data. Results To compare apical organs and larval body patterning, we have studied regionalization of the episphere, the upper hemisphere of the trochophore larva of the marine annelid Platynereis dumerilii. We examined the spatial distribution of transcription factors and of Wnt signaling components previously implicated in anterior neural development. Pharmacological activation of Wnt signaling with Gsk3β antagonists abolishes expression of apical markers, consistent with a repressive role of Wnt signaling in the specification of apical tissue. We refer to this Wnt-sensitive, six3- and foxq2-expressing part of the episphere as the ‘apical plate’. We also unraveled a molecular signature of the apical organ - devoid of six3 but expressing foxj, irx, nkx3 and hox - that is shared with other marine phyla including cnidarians. Finally, we characterized the cell types that form part of the apical organ by profiling by image registration, which allows parallel expression profiling of multiple cells. Besides the hox-expressing apical tuft cells, this revealed the presence of putative light- and mechanosensory as well as multiple peptidergic cell types that we compared to apical organ cell types of other animal phyla. Conclusions The similar formation of a six3+, foxq2+ apical plate, sensitive to Wnt activity and with an apical tuft in its six3-free center, is most parsimoniously explained by evolutionary conservation. We propose that a simple apical organ - comprising an apical tuft and a basal plexus innervated by sensory-neurosecretory apical plate cells - was present in the last common ancestors of cnidarians and bilaterians. One of its ancient functions would have been the control of metamorphosis. Various types of apical plate cells would then have subsequently been added to the apical organ in the divergent bilaterian lineages. Our findings support an ancient and common origin of primary ciliated larvae.
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Affiliation(s)
- Heather Marlow
- European Molecular Biology Laboratory, Development Biology Unit, EMBL Heidelberg, Meyerhofstraße 1, 69117 Heidelberg, Germany.
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Conzelmann M, Williams EA, Krug K, Franz-Wachtel M, Macek B, Jékely G. The neuropeptide complement of the marine annelid Platynereis dumerilii. BMC Genomics 2013; 14:906. [PMID: 24359412 PMCID: PMC3890597 DOI: 10.1186/1471-2164-14-906] [Citation(s) in RCA: 99] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2013] [Accepted: 12/17/2013] [Indexed: 11/30/2022] Open
Abstract
Background The marine annelid Platynereis dumerilii is emerging as a powerful lophotrochozoan experimental model for evolutionary developmental biology (evo-devo) and neurobiology. Recent studies revealed the presence of conserved neuropeptidergic signaling in Platynereis, including vasotocin/neurophysin, myoinhibitory peptide and opioid peptidergic systems. Despite these advances, comprehensive peptidome resources have yet to be reported. Results The present work describes the neuropeptidome of Platynereis. We established a large transcriptome resource, consisting of stage-specific next-generation sequencing datasets and 77,419 expressed sequence tags. Using this information and a combination of bioinformatic searches and mass spectrometry analyses, we increased the known proneuropeptide (pNP) complement of Platynereis to 98. Based on sequence homology to metazoan pNPs, Platynereis pNPs were grouped into ancient eumetazoan, bilaterian, protostome, lophotrochozoan, and annelid families, and pNPs only found in Platynereis. Compared to the planarian Schmidtea mediterranea, the only other lophotrochozoan with a large-scale pNP resource, Platynereis has a remarkably full complement of conserved pNPs, with 53 pNPs belonging to ancient eumetazoan or bilaterian families. Our comprehensive search strategy, combined with analyses of sequence conservation, also allowed us to define several novel lophotrochozoan and annelid pNP families. The stage-specific transcriptome datasets also allowed us to map changes in pNP expression throughout the Platynereis life cycle. Conclusion The large repertoire of conserved pNPs in Platynereis highlights the usefulness of annelids in comparative neuroendocrinology. This work establishes a reference dataset for comparative peptidomics in lophotrochozoans and provides the basis for future studies of Platynereis peptidergic signaling.
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Affiliation(s)
- Markus Conzelmann
- Max Planck Institute for Developmental Biology, Spemannstrasse 35, 72076, Tübingen, Germany.
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Marlow H, Matus DQ, Martindale MQ. Ectopic activation of the canonical wnt signaling pathway affects ectodermal patterning along the primary axis during larval development in the anthozoan Nematostella vectensis. Dev Biol 2013; 380:324-34. [PMID: 23722001 PMCID: PMC4792810 DOI: 10.1016/j.ydbio.2013.05.022] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2012] [Revised: 04/22/2013] [Accepted: 05/20/2013] [Indexed: 10/26/2022]
Abstract
The primary axis of cnidarians runs from the oral pole to the apical tuft and defines the major body axis of both the planula larva and adult polyp. In the anthozoan cnidarian Nematostella vectensis, the primary oral-aboral (O-Ab) axis first develops during the early embryonic stage. Here, we present evidence that pharmaceutical activators of canonical wnt signaling affect molecular patterning along the primary axis of Nematostella. Although not overtly morphologically complex, molecular investigations in Nematostella reveal that the O-Ab axis is demarcated by the expression of differentially localized signaling molecules and transcription factors that may serve roles in establishing distinct ectodermal domains. We have further characterized the larval epithelium by determining the position of a nested set of molecular boundaries, utilizing several newly characterized as well as previously reported epithelial markers along the primary axis. We have assayed shifts in their position in control embryos and in embryos treated with the pharmacological agents alsterpaullone and azakenpaullone, Gsk3β inhibitors that act as canonical wnt agonists, and the Wnt antagonist iCRT14, following gastrulation. Agonist drug treatments result in an absence of aboral markers, a shift in the expression boundaries of oral markers toward the aboral pole, and changes in the position of differentially localized populations of neurons in a dose-dependent manner, while antagonist treatment had the opposite effect. These experiments are consistent with canonical wnt signaling playing a role in an orally localized wnt signaling center. These findings suggest that in Nematostella, wnt signaling mediates O-Ab ectodermal patterning across a surprisingly complex epithelium in planula stages following gastrulation in addition to previously described roles for the wnt signaling pathway in endomesoderm specification during gastrulation and overall animal-vegetal patterning at earlier stages of anthozoan development.
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Theveneau E, Steventon B, Scarpa E, Garcia S, Trepat X, Streit A, Mayor R. Chase-and-run between adjacent cell populations promotes directional collective migration. Nat Cell Biol 2013; 15:763-72. [PMID: 23770678 PMCID: PMC4910871 DOI: 10.1038/ncb2772] [Citation(s) in RCA: 200] [Impact Index Per Article: 18.2] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2013] [Accepted: 04/30/2013] [Indexed: 12/03/2022]
Abstract
Collective cell migration in morphogenesis and cancer progression often involves the coordination of multiple cell types. How reciprocal interactions between adjacent cell populations lead to new emergent behaviours remains unknown. Here we studied the interaction between Neural Crest (NC) cells, a highly migratory cell population, and placodal cells, an epithelial tissue that contributes to sensory organs. We found that NC cells “chase” placodal cells by chemotaxis, while placodal cells “run” when contacted by NC. Chemotaxis to Sdf1 underlies the chase, while repulsion involving PCP and N-Cadherin signalling is responsible for the run. This “chase-and-run” requires the generation of asymmetric forces, which depend on local inhibition of focal adhesions. The cell interactions described here are essential for correct NC migration and for segregation of placodes in vivo and are likely to represent a general mechanism of coordinated migration.
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Affiliation(s)
- Eric Theveneau
- Department of Cell and Developmental Biology, University College London, London WC1E 6BT, UK
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Randel N, Bezares-Calderón LA, Gühmann M, Shahidi R, Jékely G. Expression dynamics and protein localization of rhabdomeric opsins in Platynereis larvae. Integr Comp Biol 2013; 53:7-16. [PMID: 23667045 PMCID: PMC3687135 DOI: 10.1093/icb/ict046] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The larval stages of polychaete annelids are often responsive to light and can possess one to six eyes. The early trochophore larvae of the errant annelid Platynereis dumerilii have a single pair of ventral eyespots, whereas older nectochaete larvae have an additional two pairs of dorsal eyes that will develop into the adult eyes. Early Platynereis trochophores show robust positive phototaxis starting on the first day of development. Even though the mechanism of phototaxis in Platynereis early trochophore larvae is well understood, no photopigment (opsin) expression has yet been described in this stage. In late trochophore larvae, a rhabdomeric-type opsin, r-opsin1, expressed in both the eyespots and the adult eyes has already been reported. Here, we identify another Platynereis rhabdomeric opsin, r-opsin3, that is expressed in a single photoreceptor in the eyespots in early trochophores, suggesting that it mediates early larval phototaxis. We also show that r-opsin1 and r-opsin3 are expressed in adjacent photoreceptor cells in the eyespots in later stages, indicating that a second eyespot-photoreceptor differentiates in late trochophore larvae. Using serial transmission electron microscopy (TEM), we identified and reconstructed both photoreceptors and a pigment cell in the late larval eyespot. We also characterized opsin expression in the adult eyes and found that the two opsins co-express there in several photoreceptor cells. Using antibodies recognizing r-opsin1 and r-opsin3 proteins, we demonstrate that both opsins localize to the rhabdomere in all six eyes. In addition, we found that r-opsin1 mRNA is localized to, and translated in, the projections of the adult eyes. The specific changes we describe in opsin transcription and translation and in the cellular complement suggest that the six larval eyes undergo spectral and functional maturation during the early planktonic phase of the Platynereis life cycle.
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Affiliation(s)
- Nadine Randel
- Max Planck Institute for Developmental Biology, Spemannstrasse 35, 72076 Tuebingen, Germany
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Genomic organization, evolution, and expression of photoprotein and opsin genes in Mnemiopsis leidyi: a new view of ctenophore photocytes. BMC Biol 2012; 10:107. [PMID: 23259493 PMCID: PMC3570280 DOI: 10.1186/1741-7007-10-107] [Citation(s) in RCA: 87] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2012] [Accepted: 12/21/2012] [Indexed: 11/26/2022] Open
Abstract
Background Calcium-activated photoproteins are luciferase variants found in photocyte cells of bioluminescent jellyfish (Phylum Cnidaria) and comb jellies (Phylum Ctenophora). The complete genomic sequence from the ctenophore Mnemiopsis leidyi, a representative of the earliest branch of animals that emit light, provided an opportunity to examine the genome of an organism that uses this class of luciferase for bioluminescence and to look for genes involved in light reception. To determine when photoprotein genes first arose, we examined the genomic sequence from other early-branching taxa. We combined our genomic survey with gene trees, developmental expression patterns, and functional protein assays of photoproteins and opsins to provide a comprehensive view of light production and light reception in Mnemiopsis. Results The Mnemiopsis genome has 10 full-length photoprotein genes situated within two genomic clusters with high sequence conservation that are maintained due to strong purifying selection and concerted evolution. Photoprotein-like genes were also identified in the genomes of the non-luminescent sponge Amphimedon queenslandica and the non-luminescent cnidarian Nematostella vectensis, and phylogenomic analysis demonstrated that photoprotein genes arose at the base of all animals. Photoprotein gene expression in Mnemiopsis embryos begins during gastrulation in migrating precursors to photocytes and persists throughout development in the canals where photocytes reside. We identified three putative opsin genes in the Mnemiopsis genome and show that they do not group with well-known bilaterian opsin subfamilies. Interestingly, photoprotein transcripts are co-expressed with two of the putative opsins in developing photocytes. Opsin expression is also seen in the apical sensory organ. We present evidence that one opsin functions as a photopigment in vitro, absorbing light at wavelengths that overlap with peak photoprotein light emission, raising the hypothesis that light production and light reception may be functionally connected in ctenophore photocytes. We also present genomic evidence of a complete ciliary phototransduction cascade in Mnemiopsis. Conclusions This study elucidates the genomic organization, evolutionary history, and developmental expression of photoprotein and opsin genes in the ctenophore Mnemiopsis leidyi, introduces a novel dual role for ctenophore photocytes in both bioluminescence and phototransduction, and raises the possibility that light production and light reception are linked in this early-branching non-bilaterian animal.
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Asadulina A, Panzera A, Verasztó C, Liebig C, Jékely G. Whole-body gene expression pattern registration in Platynereis larvae. EvoDevo 2012. [PMID: 23199348 PMCID: PMC3586958 DOI: 10.1186/2041-9139-3-27] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022] Open
Abstract
Background Digital anatomical atlases are increasingly used in order to depict different gene expression patterns and neuronal morphologies within a standardized reference template. In evo-devo, a discipline in which the comparison of gene expression patterns is a widely used approach, such standardized anatomical atlases would allow a more rigorous assessment of the conservation of and changes in gene expression patterns during micro- and macroevolutionary time scales. Due to its small size and invariant early development, the annelid Platynereis dumerilii is particularly well suited for such studies. Recently a reference template with registered gene expression patterns has been generated for the anterior part (episphere) of the Platynereis trochophore larva and used for the detailed study of neuronal development. Results Here we introduce and evaluate a method for whole-body gene expression pattern registration for Platynereis trochophore and nectochaete larvae based on whole-mount in situ hybridization, confocal microscopy, and image registration. We achieved high-resolution whole-body scanning using the mounting medium 2,2’-thiodiethanol (TDE), which allows the matching of the refractive index of the sample to that of glass and immersion oil thereby reducing spherical aberration and improving depth penetration. This approach allowed us to scan entire whole-mount larvae stained with nitroblue tetrazolium/5-bromo-4-chloro-3-indolyl phosphate (NBT/BCIP) in situ hybridization and counterstained fluorescently with an acetylated-tubulin antibody and the nuclear stain 4’6-diamidino-2-phenylindole (DAPI). Due to the submicron isotropic voxel size whole-mount larvae could be scanned in any orientation. Based on the whole-body scans, we generated four different reference templates by the iterative registration and averaging of 40 individual image stacks using either the acetylated-tubulin or the nuclear-stain signal for each developmental stage. We then registered to these templates the expression patterns of cell-type specific genes. In order to evaluate the gene expression pattern registration, we analyzed the absolute deviation of cell-center positions. Both the acetylated-tubulin- and the nuclear-stain-based templates allowed near-cellular-resolution gene expression registration. Nuclear-stain-based templates often performed significantly better than acetylated-tubulin-based templates. We provide detailed guidelines and scripts for the use and further expansion of the Platynereis gene expression atlas. Conclusions We established whole-body reference templates for the generation of gene expression atlases for Platynereis trochophore and nectochaete larvae. We anticipate that nuclear-staining-based image registration will be applicable for whole-body alignment of the embryonic and larval stages of other organisms in a similar size range.
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Affiliation(s)
- Albina Asadulina
- Max Planck Institute for Developmental Biology, Spemannstrasse 35, Tübingen, 72076, Germany.
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Simakov O, Larsson TA, Arendt D. Linking micro- and macro-evolution at the cell type level: a view from the lophotrochozoan Platynereis dumerilii. Brief Funct Genomics 2012; 12:430-9. [DOI: 10.1093/bfgp/els049] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
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Conzelmann M, Jékely G. Antibodies against conserved amidated neuropeptide epitopes enrich the comparative neurobiology toolbox. EvoDevo 2012; 3:23. [PMID: 23020891 PMCID: PMC3503879 DOI: 10.1186/2041-9139-3-23] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2012] [Accepted: 07/23/2012] [Indexed: 11/28/2022] Open
Abstract
Background Neuronal antibodies that show immunoreactivity across a broad range of species are important tools for comparative neuroanatomy. Nonetheless, the current antibody repertoire for non-model invertebrates is limited. Currently, only antibodies against the neuropeptide RFamide and the monoamine transmitter serotonin are extensively used. These antibodies label respective neuron-populations and their axons and dendrites in a large number of species across various animal phyla. Results Several other neuropeptides also have a broad phyletic distribution among invertebrates, including DLamides, FVamides, FLamides, GWamides and RYamides. These neuropeptides show strong conservation of the two carboxy-terminal amino acids and are α-amidated at their C-termini. We generated and affinity-purified specific polyclonal antibodies against each of these conserved amidated dipeptide motifs. We thoroughly tested antibody reactivity and specificity both by peptide pre-incubation experiments and by showing a close correlation between the immunostaining signals and mRNA expression patterns of the respective precursor genes in the annelid Platynereis. We also demonstrated the usefulness of these antibodies by performing immunostainings on a broad range of invertebrate species, including cnidarians, annelids, molluscs, a bryozoan, and a crustacean. In all species, the antibodies label distinct neuronal populations and their axonal projections. In the ciliated larvae of cnidarians, annelids, molluscs and bryozoans, a subset of antibodies reveal peptidergic innervation of locomotor cilia. Conclusions We developed five specific cross-species-reactive antibodies recognizing conserved two-amino-acid amidated neuropeptide epitopes. These antibodies allow specific labelling of peptidergic neurons and their projections in a broad range of invertebrates. Our comparative survey across several marine phyla demonstrates a broad occurrence of peptidergic innervation of larval ciliary bands, suggesting a general role of these neuropeptides in the regulation of ciliary swimming.
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Affiliation(s)
- Markus Conzelmann
- Max Planck Institute for Developmental Biology, Spemannstrasse 35, Tübingen 72076, Germany.
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Abstract
Annelids (the segmented worms) have a long history in studies of animal developmental biology, particularly with regards to their cleavage patterns during early development and their neurobiology. With the relatively recent reorganisation of the phylogeny of the animal kingdom, and the distinction of the super-phyla Ecdysozoa and Lophotrochozoa, an extra stimulus for studying this phylum has arisen. As one of the major phyla within Lophotrochozoa, Annelida are playing an important role in deducing the developmental biology of the last common ancestor of the protostomes and deuterostomes, an animal from which >98% of all described animal species evolved.
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Affiliation(s)
- David E. K. Ferrier
- The Scottish Oceans Institute, the Gatty Marine Laboratory, University of St Andrews, East Sands, St Andrews, Fife, KY16 8LB, UK
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Dalgin G, Ward AB, Hao LT, Beattie CE, Nechiporuk A, Prince VE. Zebrafish mnx1 controls cell fate choice in the developing endocrine pancreas. Development 2011; 138:4597-608. [PMID: 21989909 DOI: 10.1242/dev.067736] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The vertebrate endocrine pancreas has the crucial function of maintaining blood sugar homeostasis. This role is dependent upon the development and maintenance of pancreatic islets comprising appropriate ratios of hormone-producing cells. In all vertebrate models studied, an initial precursor population of Pdx1-expressing endoderm cells gives rise to separate endocrine and exocrine cell lineages. Within the endocrine progenitor pool a variety of transcription factors influence cell fate decisions, such that hormone-producing differentiated cell types ultimately arise, including the insulin-producing beta cells and the antagonistically acting glucagon-producing alpha cells. In previous work, we established that the development of all pancreatic lineages requires retinoic acid (RA) signaling. We have used the zebrafish to uncover genes that function downstream of RA signaling, and here we identify mnx1 (hb9) as an RA-regulated endoderm transcription factor-encoding gene. By combining manipulation of gene function, cell transplantation approaches and transgenic reporter analysis we establish that Mnx1 functions downstream of RA within the endoderm to control cell fate decisions in the endocrine pancreas progenitor lineage. We confirm that Mnx1-deficient zebrafish lack beta cells, and, importantly, we make the novel observation that they concomitantly gain alpha cells. In Mnx1-deficient embryos, precursor cells that are normally destined to differentiate as beta cells instead take on an alpha cell fate. Our findings suggest that Mnx1 functions to promote beta and suppress alpha cell fates.
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Affiliation(s)
- Gokhan Dalgin
- Department of Organismal Biology and Anatomy, University of Chicago, Chicago, IL 60637, USA
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Abstract
Cilia-based locomotion is the major form of locomotion for microscopic planktonic organisms in the ocean. Given their negative buoyancy, these organisms must control ciliary activity to maintain an appropriate depth. The neuronal bases of depth regulation in ciliary swimmers are unknown. To gain insights into depth regulation we studied ciliary locomotor control in the planktonic larva of the marine annelid, Platynereis. We found several neuropeptides expressed in distinct sensory neurons that innervate locomotor cilia. Neuropeptides altered ciliary beat frequency and the rate of calcium-evoked ciliary arrests. These changes influenced larval orientation, vertical swimming, and sinking, resulting in upward or downward shifts in the steady-state vertical distribution of larvae. Our findings indicate that Platynereis larvae have depth-regulating peptidergic neurons that directly translate sensory inputs into locomotor output on effector cilia. We propose that the simple circuitry found in these ciliated larvae represents an ancestral state in nervous system evolution.
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Coe genes are expressed in differentiating neurons in the central nervous system of protostomes. PLoS One 2011; 6:e21213. [PMID: 21695052 PMCID: PMC3117877 DOI: 10.1371/journal.pone.0021213] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2011] [Accepted: 05/23/2011] [Indexed: 11/19/2022] Open
Abstract
Genes of the coe (collier/olfactory/early B-cell factor) family encode Helix-Loop-Helix transcription factors that are widely conserved in metazoans and involved in many developmental processes, neurogenesis in particular. Whereas their functions during vertebrate neural tube formation have been well documented, very little is known about their expression and role during central nervous system (CNS) development in protostomes. Here we characterized the CNS expression of coe genes in the insect Drosophila melanogaster and the polychaete annelid Platynereis dumerilii, which belong to different subgroups of protostomes and show strikingly different modes of development. In the Drosophila ventral nerve cord, we found that the Collier-expressing cells form a subpopulation of interneurons with diverse molecular identities and neurotransmitter phenotypes. We also demonstrate that collier is required for the proper differentiation of some interneurons belonging to the Eve-Lateral cluster. In Platynereis dumerilii, we cloned a single coe gene, Pdu-coe, and found that it is exclusively expressed in post mitotic neural cells. Using an original technique of in silico 3D registration, we show that Pdu-coe is co-expressed with many different neuronal markers and therefore that, like in Drosophila, its expression defines a heterogeneous population of neurons with diverse molecular identities. Our detailed characterization and comparison of coe gene expression in the CNS of two distantly-related protostomes suggest conserved roles of coe genes in neuronal differentiation in this clade. As similar roles have also been observed in vertebrates, this function was probably already established in the last common ancestor of all bilaterians.
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Tessmar-Raible K, Raible F, Arboleda E. Another place, another timer: Marine species and the rhythms of life. Bioessays 2011; 33:165-72. [PMID: 21254149 PMCID: PMC3182551 DOI: 10.1002/bies.201000096] [Citation(s) in RCA: 98] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
The marine ecosystem is governed by a multitude of environmental cycles, all of which are linked to the periodical recurrence of the sun or the moon. In accordance with these cycles, marine species exhibit a variety of biological rhythms, ranging from circadian and circatidal rhythms to circalunar and seasonal rhythms. However, our current molecular understanding of biological rhythms and clocks is largely restricted to solar-controlled circadian and seasonal rhythms in land model species. Here, we discuss the first molecular data emerging for circalunar and circatidal rhythms and present selected species suitable for further molecular analyses. We argue that a re-focus on marine species will be crucial to understand the principles, interactions and evolution of rhythms that govern a broad range of eukaryotes, including ourselves.
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Abstract
Examination of spatial and temporal gene expression pattern is a key step towards understanding gene function. Therefore, in situ hybridization of mRNA is one of the most powerful and widely used -techniques in biology. Recent advances allow the reliable and simultaneous detection of mRNA transcripts, or combinations of mRNA and protein, in zebrafish embryos.Here we describe a standard protocol for visualizing the precise expression pattern of a single transcript or multiple gene products. The procedure employs fixation and permeabilization of embryos, followed by hybridization with tagged antisense riboprobes. Excess probes are then washed and hybrids are detected by enzyme-mediated immunohistochemistry utilizing either chromogenic or fluorescent substrates.
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Affiliation(s)
- Yossy Machluf
- Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot, Israel
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Swanson SJ, Choi WG, Chanoca A, Gilroy S. In vivo imaging of Ca2+, pH, and reactive oxygen species using fluorescent probes in plants. ANNUAL REVIEW OF PLANT BIOLOGY 2011; 62:273-97. [PMID: 21370977 DOI: 10.1146/annurev-arplant-042110-103832] [Citation(s) in RCA: 109] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Changes in the levels of Ca(2+), pH, and reactive oxygen species (ROS) are recognized as key cellular regulators involved in diverse physiological and developmental processes in plants. Critical to understanding how they exert such widespread control is an appreciation of their spatial and temporal dynamics at levels from organ to organelle and from seconds to many hours. With appropriate controls, fluorescent sensors can provide a robust approach with which to quantify such changes in Ca(2+), pH, and ROS in real time, in vivo. The fluorescent cellular probes available for visualization split into two broad classes: (a) dyes and (b) an increasingly diverse set of genetically encoded sensors based around green fluorescent proteins (GFPs). The GFP probes in particular can be targeted to well-defined subcellular locales, offering the possibility of high-resolution mapping of these signals within the cell.
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Affiliation(s)
- Sarah J Swanson
- Department of Botany, University of Wisconsin, Madison, Wisconsin 53706, USA.
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Fischer AHL, Henrich T, Arendt D. The normal development of Platynereis dumerilii (Nereididae, Annelida). Front Zool 2010; 7:31. [PMID: 21192805 PMCID: PMC3027123 DOI: 10.1186/1742-9994-7-31] [Citation(s) in RCA: 115] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2010] [Accepted: 12/30/2010] [Indexed: 12/14/2022] Open
Abstract
BACKGROUND The polychaete annelid Platynereis dumerilii is an emerging model organism for the study of molecular developmental processes, evolution, neurobiology and marine biology. Annelids belong to the Lophotrochozoa, the so far understudied third major branch of bilaterian animals besides deuterostomes and ecdysozoans. P. dumerilii has proven highly relevant to explore ancient bilaterian conditions via comparison to the deuterostomes, because it has accumulated less evolutionary change than conventional ecdysozoan models. Previous staging was mainly referring to hours post fertilization but did not allow matching stages between studies performed at (even slightly) different temperatures. To overcome this, and to provide a first comprehensive description of P. dumerilii normal development, a temperature-independent staging system is needed. RESULTS Platynereis dumerilii normal development is subdivided into 16 stages, starting with the zygote and ending with the death of the mature worms after delivering their gametes. The stages described can be easily identified by conventional light microscopy or even by dissecting scope. Developmental landmarks such as the beginning of phototaxis, the visibility of the stomodeal opening and of the chaetae, the first occurrence of the ciliary bands, the formation of the parapodia, the extension of antennae and cirri, the onset of feeding and other characteristics are used to define different developmental stages. The morphology of all larval stages as well as of juveniles and adults is documented by light microscopy. We also provide an overview of important steps in the development of the nervous system and of the musculature, using fluorescent labeling techniques and confocal laser-scanning microscopy. Timing of each developmental stage refers to hours post fertilization at 18 ± 0.1°C. For comparison, we determined the pace of development of larvae raised at 14°C, 16°C, 20°C, 25°C, 28°C and 30°C. A staging ontology representing the comprehensive list of developmental stages of P. dumerilii is available online. CONCLUSIONS Our atlas of Platynereis dumerilii normal development represents an important resource for the growing Platynereis community and can also be applied to other nereidid annelids.
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Affiliation(s)
- Antje HL Fischer
- Developmental Biology Unit, European Molecular Biology Laboratory, D-69117 Heidelberg, Germany
| | - Thorsten Henrich
- Developmental Biology Unit, European Molecular Biology Laboratory, D-69117 Heidelberg, Germany
- International College, Osaka University, A217 School of Science Main Building 1-1, Machikaneyama-machi, Toyonaka, Osaka, 560-0043, Japan
| | - Detlev Arendt
- Developmental Biology Unit, European Molecular Biology Laboratory, D-69117 Heidelberg, Germany
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Van Otterloo E, Li W, Bonde G, Day KM, Hsu MY, Cornell RA. Differentiation of zebrafish melanophores depends on transcription factors AP2 alpha and AP2 epsilon. PLoS Genet 2010; 6:e1001122. [PMID: 20862309 PMCID: PMC2940735 DOI: 10.1371/journal.pgen.1001122] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2009] [Accepted: 08/13/2010] [Indexed: 11/30/2022] Open
Abstract
A model of the gene-regulatory-network (GRN), governing growth, survival, and differentiation of melanocytes, has emerged from studies of mouse coat color mutants and melanoma cell lines. In this model, Transcription Factor Activator Protein 2 alpha (TFAP2A) contributes to melanocyte development by activating expression of the gene encoding the receptor tyrosine kinase Kit. Next, ligand-bound Kit stimulates a pathway activating transcription factor Microphthalmia (Mitf), which promotes differentiation and survival of melanocytes by activating expression of Tyrosinase family members, Bcl2, and other genes. The model predicts that in both Tfap2a and Kit null mutants there will be a phenotype of reduced melanocytes and that, because Tfap2a acts upstream of Kit, this phenotype will be more severe, or at least as severe as, in Tfap2a null mutants in comparison to Kit null mutants. Unexpectedly, this is not the case in zebrafish or mouse. Because many Tfap2 family members have identical DNA–binding specificity, we reasoned that another Tfap2 family member may work redundantly with Tfap2a in promoting Kit expression. We report that tfap2e is expressed in melanoblasts and melanophores in zebrafish embryos and that its orthologue, TFAP2E, is expressed in human melanocytes. We provide evidence that Tfap2e functions redundantly with Tfap2a to maintain kita expression in zebrafish embryonic melanophores. Further, we show that, in contrast to in kita mutants where embryonic melanophores appear to differentiate normally, in tfap2a/e doubly-deficient embryonic melanophores are small and under-melanized, although they retain expression of mitfa. Interestingly, forcing expression of mitfa in tfap2a/e doubly-deficient embryos partially restores melanophore differentiation. These findings reveal that Tfap2 activity, mediated redundantly by Tfap2a and Tfap2e, promotes melanophore differentiation in parallel with Mitf by an effector other than Kit. This work illustrates how analysis of single-gene mutants may fail to identify steps in a GRN that are affected by the redundant activity of related proteins. Neural crest-derived pigment cells, known as melanocytes, are important to an organism's survival because they protect skin cells from ultraviolet radiation, camouflage the organism from predators, and contribute to sexual selection. Networks of regulatory proteins control the steps of melanocyte development, including lineage specification, migration, survival, and differentiation. Gaps in our understanding of these networks hamper progress in effective prevention and treatment of diseases of melanocytes, including metastatic melanoma and vitiligo. Studies conducted in tissue-culture cells and mouse embryos implicate regulatory proteins including the transcription factor TFAP2A, the growth factor receptor KIT, and the transcription factor MITF as being important for multiple steps in melanocyte development. Abnormalities in TFAP2A, KIT, and MITF expression in melanoma highlight the importance of this pathway in human disease. Here we show that a gene closely related to TFAP2A, tfap2e, is expressed in zebrafish embryonic melanocytes and human melanocytes. We provide evidence that Tfap2e cooperates with Tfap2a to promote expression of zebrafish kita in embryonic melanocytes. Further we show that an effector of Tfap2a/e activity other than Kita is required for melanocyte differentiation and that this effector acts upstream or in parallel with Mitfa activity. These findings reveal unexpected complexity to the gene-regulatory network governing melanocyte differentiation.
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Affiliation(s)
- Eric Van Otterloo
- Department of Anatomy and Cell Biology, University of Iowa, Iowa City, Iowa, USA
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Irimia M, Piñeiro C, Maeso I, Gómez-Skarmeta JL, Casares F, Garcia-Fernàndez J. Conserved developmental expression of Fezf in chordates and Drosophila and the origin of the Zona Limitans Intrathalamica (ZLI) brain organizer. EvoDevo 2010; 1:7. [PMID: 20849572 PMCID: PMC2942887 DOI: 10.1186/2041-9139-1-7] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2010] [Accepted: 09/01/2010] [Indexed: 01/17/2023] Open
Abstract
Background The zona limitans intrathalamica (ZLI) and the isthmus organizer (IsO) are two major secondary organizers of vertebrate brain development. These organizers are located at the interface of the expression domains of key patterning genes (Fezf-Irx and Otx-Gbx, respectively). To gain insights into the evolutionary origin of the ZLI, we studied Fezf in bilaterians. Results In this paper, we identified a conserved sequence motif (Fezf box) in all bilaterians. We report the expression pattern of Fezf in amphioxus and Drosophila and compare it with those of Gbx, Otx and Irx. We found that the relative expression patterns of these genes in vertebrates are fully conserved in amphioxus and flies, indicating that the genetic subdivisions defining the location of both secondary organizers in early vertebrate brain development were probably present in the last common ancestor of extant bilaterians. However, in contrast to vertebrates, we found that Irx-defective flies do not show an affected Fezf expression pattern. Conclusions The absence of expression of the corresponding morphogens from cells at these conserved genetic boundaries in invertebrates suggests that the organizing properties might have evolved specifically in the vertebrate lineage by the recruitment of key morphogens to these conserved genetic locations.
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Affiliation(s)
- Manuel Irimia
- Departament de Genètica and Institut de Biomedicina (IBUB), Universitat de Barcelona, Barcelona, Spain.
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Tomer R, Denes AS, Tessmar-Raible K, Arendt D. Profiling by Image Registration Reveals Common Origin of Annelid Mushroom Bodies and Vertebrate Pallium. Cell 2010; 142:800-9. [DOI: 10.1016/j.cell.2010.07.043] [Citation(s) in RCA: 182] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2010] [Revised: 05/22/2010] [Accepted: 07/14/2010] [Indexed: 01/08/2023]
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Lopes CS, Casares F. hth maintains the pool of eye progenitors and its downregulation by Dpp and Hh couples retinal fate acquisition with cell cycle exit. Dev Biol 2010; 339:78-88. [DOI: 10.1016/j.ydbio.2009.12.020] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2009] [Revised: 12/11/2009] [Accepted: 12/12/2009] [Indexed: 01/11/2023]
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Ancient animal microRNAs and the evolution of tissue identity. Nature 2010; 463:1084-8. [PMID: 20118916 DOI: 10.1038/nature08744] [Citation(s) in RCA: 220] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2009] [Accepted: 12/04/2009] [Indexed: 12/13/2022]
Abstract
The spectacular escalation in complexity in early bilaterian evolution correlates with a strong increase in the number of microRNAs. To explore the link between the birth of ancient microRNAs and body plan evolution, we set out to determine the ancient sites of activity of conserved bilaterian microRNA families in a comparative approach. We reason that any specific localization shared between protostomes and deuterostomes (the two major superphyla of bilaterian animals) should probably reflect an ancient specificity of that microRNA in their last common ancestor. Here, we investigate the expression of conserved bilaterian microRNAs in Platynereis dumerilii, a protostome retaining ancestral bilaterian features, in Capitella, another marine annelid, in the sea urchin Strongylocentrotus, a deuterostome, and in sea anemone Nematostella, representing an outgroup to the bilaterians. Our comparative data indicate that the oldest known animal microRNA, miR-100, and the related miR-125 and let-7 were initially active in neurosecretory cells located around the mouth. Other sets of ancient microRNAs were first present in locomotor ciliated cells, specific brain centres, or, more broadly, one of four major organ systems: central nervous system, sensory tissue, musculature and gut. These findings reveal that microRNA evolution and the establishment of tissue identities were closely coupled in bilaterian evolution. Also, they outline a minimum set of cell types and tissues that existed in the protostome-deuterostome ancestor.
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Hejnol A, Martindale MQ. Coordinated spatial and temporal expression of Hox genes during embryogenesis in the acoel Convolutriloba longifissura. BMC Biol 2009; 7:65. [PMID: 19796382 PMCID: PMC2761877 DOI: 10.1186/1741-7007-7-65] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2009] [Accepted: 10/01/2009] [Indexed: 11/16/2022] Open
Abstract
Background Hox genes are critical for patterning the bilaterian anterior-posterior axis. The evolution of their clustered genomic arrangement and ancestral function has been debated since their discovery. As acoels appear to represent the sister group to the remaining Bilateria (Nephrozoa), investigating Hox gene expression will provide an insight into the ancestral features of the Hox genes in metazoan evolution. Results We describe the expression of anterior, central and posterior class Hox genes and the ParaHox ortholog Cdx in the acoel Convolutriloba longifissura. Expression of all three Hox genes begins contemporaneously after gastrulation and then resolves into staggered domains along the anterior-posterior axis, suggesting that the spatial coordination of Hox gene expression was present in the bilaterian ancestor. After early surface ectodermal expression, the anterior and central class genes are expressed in small domains of putative neural precursor cells co-expressing ClSoxB1, suggesting an evolutionary early function of Hox genes in patterning parts of the nervous system. In contrast, the expression of the posterior Hox gene is found in all three germ layers in a much broader posterior region of the embryo. Conclusion Our results suggest that the ancestral set of Hox genes was involved in the anterior-posterior patterning of the nervous system of the last common bilaterian ancestor and were later co-opted for patterning in diverse tissues in the bilaterian radiation. The lack of temporal colinearity of Hox expression in acoels may be due to a loss of genomic clustering in this clade or, alternatively, temporal colinearity may have arisen in conjunction with the expansion of the Hox cluster in the Nephrozoa.
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Affiliation(s)
- Andreas Hejnol
- Kewalo Marine Laboratory, PBRC, University of Hawaii, 41 Ahui Street, Honolulu, HI 96813, USA.
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Kerner P, Simionato E, Le Gouar M, Vervoort M. Orthologs of key vertebrate neural genes are expressed during neurogenesis in the annelidPlatynereis dumerilii. Evol Dev 2009; 11:513-24. [DOI: 10.1111/j.1525-142x.2009.00359.x] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Lee C, Le MP, Wallingford JB. The shroom family proteins play broad roles in the morphogenesis of thickened epithelial sheets. Dev Dyn 2009; 238:1480-91. [PMID: 19384856 PMCID: PMC2699254 DOI: 10.1002/dvdy.21942] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Thickened epithelial sheets are found in a wide variety of organ systems and the mechanisms governing their morphogenesis remain poorly defined. We show here, through expression patterns and functional studies, that Shroom family proteins are broadly involved in generating thickened epithelial sheets. Through in situ hybridization, we report the temporal and spatial expression patterns of the four Shroom family members during early Xenopus development, from oocytes to tadpole stage embryos. Further, we show that Shroom1 and 2 mRNAs are maternally expressed, while Shroom3 and Shroom4 are zygotic transcripts. In addition, maternal Shroom1 and 2 mRNAs localize in the animal hemisphere of the Xenopus egg and early blastula. During later development, all four Shroom family proteins are broadly expressed in developing epithelial organs, and the epithelial cells that express Shrooms are elongated. Moreover, we show that ectopic expression of Shroom2, like Shroom3, is able to increase cell height and that loss of Shroom2 function results in a failure of cell elongation in the neural epithelium. Together, these data suggest that Shroom family proteins play an important role in the morphogenesis of several different epithelial tissues during development. Developmental Dynamics 238:1480-1491, 2009. (c) 2009 Wiley-Liss, Inc.
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Affiliation(s)
- Chanjae Lee
- Department of Molecular Cell and Developmental Biology and Institute for Cellular and Molecular Biology, University of Texas, Austin, Texas, USA
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Kerner P, Hung J, Béhague J, Le Gouar M, Balavoine G, Vervoort M. Insights into the evolution of the snail superfamily from metazoan wide molecular phylogenies and expression data in annelids. BMC Evol Biol 2009; 9:94. [PMID: 19426549 PMCID: PMC2688512 DOI: 10.1186/1471-2148-9-94] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2008] [Accepted: 05/09/2009] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND An important issue concerning the evolution of duplicated genes is to understand why paralogous genes are retained in a genome even though the most likely fate for a redundant duplicated gene is nonfunctionalization and thereby its elimination. Here we study a complex superfamily generated by gene duplications, the snail related genes that play key roles during animal development. We investigate the evolutionary history of these genes by genomic, phylogenetic, and expression data studies. RESULTS We systematically retrieved the full complement of snail related genes in several sequenced genomes. Through phylogenetic analysis, we found that the snail superfamily is composed of three ancestral families, snail, scratchA and scratchB. Analyses of the organization of the encoded proteins point out specific molecular signatures, indicative of functional specificities for Snail, ScratchA and ScratchB proteins. We also report the presence of two snail genes in the annelid Platynereis dumerilii, which have distinct expression patterns in the developing mesoderm, nervous system, and foregut. The combined expression of these two genes is identical to that of two independently duplicated snail genes in another annelid, Capitella spI, but different aspects of the expression patterns are differentially shared among paralogs of Platynereis and Capitella. CONCLUSION Our study indicates that the snail and scratchB families have expanded through multiple independent gene duplications in the different bilaterian lineages, and highlights potential functional diversifications of Snail and ScratchB proteins following duplications, as, in several instances, paralogous proteins in a given species show different domain organizations. Comparisons of the expression pattern domains of the two Platynereis and Capitella snail paralogs provide evidence for independent subfunctionalization events which have occurred in these two species. We propose that the snail related genes may be especially prone to subfunctionalization, and this would explain why the snail superfamily underwent so many independent duplications leading to maintenance of functional paralogs.
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Affiliation(s)
- Pierre Kerner
- Programme Development and Neurobiology, Institut Jacques Monod, UMR 7592 CNRS/Université Paris Diderot – Paris 7, 15 rue Hélène Brion, 75205 Paris Cedex 13, France
- Evolution et Développement des Métazoaires, Centre de Génétique Moléculaire- FRE 3144 CNRS, 1, av. de la terrasse, 91198 Gif-sur-Yvette, France
- UFR des Sciences du Vivant, Université Paris Diderot – Paris 7, 5, rue Marie-Andrée Lagroua Weill-Hallé, 75205 Paris Cedex 13, France
| | - Johanne Hung
- Evolution et Développement des Métazoaires, Centre de Génétique Moléculaire- FRE 3144 CNRS, 1, av. de la terrasse, 91198 Gif-sur-Yvette, France
| | - Julien Béhague
- Programme Development and Neurobiology, Institut Jacques Monod, UMR 7592 CNRS/Université Paris Diderot – Paris 7, 15 rue Hélène Brion, 75205 Paris Cedex 13, France
- Evolution et Développement des Métazoaires, Centre de Génétique Moléculaire- FRE 3144 CNRS, 1, av. de la terrasse, 91198 Gif-sur-Yvette, France
| | - Martine Le Gouar
- Evolution et Développement des Métazoaires, Centre de Génétique Moléculaire- FRE 3144 CNRS, 1, av. de la terrasse, 91198 Gif-sur-Yvette, France
| | - Guillaume Balavoine
- Programme Development and Neurobiology, Institut Jacques Monod, UMR 7592 CNRS/Université Paris Diderot – Paris 7, 15 rue Hélène Brion, 75205 Paris Cedex 13, France
- Evolution et Développement des Métazoaires, Centre de Génétique Moléculaire- FRE 3144 CNRS, 1, av. de la terrasse, 91198 Gif-sur-Yvette, France
| | - Michel Vervoort
- Programme Development and Neurobiology, Institut Jacques Monod, UMR 7592 CNRS/Université Paris Diderot – Paris 7, 15 rue Hélène Brion, 75205 Paris Cedex 13, France
- Evolution et Développement des Métazoaires, Centre de Génétique Moléculaire- FRE 3144 CNRS, 1, av. de la terrasse, 91198 Gif-sur-Yvette, France
- UFR des Sciences du Vivant, Université Paris Diderot – Paris 7, 5, rue Marie-Andrée Lagroua Weill-Hallé, 75205 Paris Cedex 13, France
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