1
|
Fridrich A, Modepalli V, Lewandowska M, Aharoni R, Moran Y. Unravelling the developmental and functional significance of an ancient Argonaute duplication. Nat Commun 2020; 11:6187. [PMID: 33273471 PMCID: PMC7713132 DOI: 10.1038/s41467-020-20003-8] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2020] [Accepted: 10/30/2020] [Indexed: 12/28/2022] Open
Abstract
MicroRNAs (miRNAs) base-pair to messenger RNA targets and guide Argonaute proteins to mediate their silencing. This target regulation is considered crucial for animal physiology and development. However, this notion is based exclusively on studies in bilaterians, which comprise almost all lab model animals. To fill this phylogenetic gap, we characterize the functions of two Argonaute paralogs in the sea anemone Nematostella vectensis of the phylum Cnidaria, which is separated from bilaterians by ~600 million years. Using genetic manipulations, Argonaute-immunoprecipitations and high-throughput sequencing, we provide experimental evidence for the developmental importance of miRNAs in a non-bilaterian animal. Additionally, we uncover unexpected differential distribution of distinct miRNAs between the two Argonautes and the ability of one of them to load additional types of small RNAs. This enables us to postulate a novel model for evolution of miRNA precursors in sea anemones and their relatives, revealing alternative trajectories for metazoan miRNA evolution.
Collapse
Affiliation(s)
- Arie Fridrich
- Department of Ecology, Evolution and Behavior, Alexander Silberman Institute of Life Sciences, Faculty of Science, The Hebrew University of Jerusalem, 9190401, Jerusalem, Israel
| | - Vengamanaidu Modepalli
- Department of Ecology, Evolution and Behavior, Alexander Silberman Institute of Life Sciences, Faculty of Science, The Hebrew University of Jerusalem, 9190401, Jerusalem, Israel
- The Marine Biological Association of the United Kingdom, Citadel Hill, Plymouth, UK
| | - Magda Lewandowska
- Department of Ecology, Evolution and Behavior, Alexander Silberman Institute of Life Sciences, Faculty of Science, The Hebrew University of Jerusalem, 9190401, Jerusalem, Israel
| | - Reuven Aharoni
- Department of Ecology, Evolution and Behavior, Alexander Silberman Institute of Life Sciences, Faculty of Science, The Hebrew University of Jerusalem, 9190401, Jerusalem, Israel
| | - Yehu Moran
- Department of Ecology, Evolution and Behavior, Alexander Silberman Institute of Life Sciences, Faculty of Science, The Hebrew University of Jerusalem, 9190401, Jerusalem, Israel.
| |
Collapse
|
2
|
Abstract
This chapter reflects on and makes explicit the distinctiveness of reasoning practices associated with model organisms in the context of evolutionary developmental research. Model organisms in evo-devo instantiate a unique synthesis of model systems strategies from developmental biology and comparative strategies from evolutionary biology that negotiate a tension between developmental conservation and evolutionary change to address scientific questions about the evolution of development and the developmental basis of evolutionary change. We review different categories of model systems that have been advanced to understand practices found in the life sciences in order to comprehend how evo-devo model organisms instantiate this synthesis in the context of three examples: the starlet sea anemone and the evolution of bilateral symmetry, leeches and the origins of segmentation in bilaterians, and the corn snake to understand major evolutionary change in axial and appendicular morphology.
Collapse
Affiliation(s)
- Alan C Love
- Department of Philosophy and Minnesota Center for Philosophy of Science, University of Minnesota - Twin Cities, Minneapolis, MN, USA.
| | - Yoshinari Yoshida
- Department of Philosophy and Minnesota Center for Philosophy of Science, University of Minnesota - Twin Cities, Minneapolis, MN, USA
| |
Collapse
|
3
|
Modepalli V, Fridrich A, Agron M, Moran Y. The methyltransferase HEN1 is required in Nematostella vectensis for microRNA and piRNA stability as well as larval metamorphosis. PLoS Genet 2018; 14:e1007590. [PMID: 30118479 PMCID: PMC6114907 DOI: 10.1371/journal.pgen.1007590] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2018] [Revised: 08/29/2018] [Accepted: 07/25/2018] [Indexed: 11/18/2022] Open
Abstract
Small non-coding RNAs (sRNAs) such as microRNAs (miRNAs), small interfering RNAs (siRNAs) and piwi-interacting RNAs (piRNAs) regulate the levels of endogenous, viral and transposable element RNA in plants (excluding piRNAs) and animals. These pathways are explored mainly in bilaterian animals, such as vertebrates, arthropods and nematodes, where siRNAs and piRNAs, but not miRNAs bind their targets with a perfect match and mediate the cleavage of the target RNA. Methylation of the 3′ ends of piRNAs and siRNAs by the methyltransferase HEN1 protects these sRNAs from degradation. There is a noticeable selection in bilaterian animals against miRNA-mRNA perfect matching, as it leads to the degradation of miRNAs. Cnidarians (sea anemones, corals, hydroids and jellyfish), are separated from bilaterians by more than 600 million years. As opposed to bilaterians, cnidarian miRNAs frequently bind their targets with a nearly perfect match. Knowing that an ortholog of HEN1 is widely expressed in the sea anemone Nematostella vectensis, we tested in this work whether it mediates the stabilization of its sRNAs. We show that the knockdown of HEN1 in Nematostella results in a developmental arrest. Small RNA sequencing revealed that the levels of both miRNAs and piRNAs drop dramatically in the morphant animals. Moreover, knockdown experiments of Nematostella Dicer1 and PIWI2, homologs of major bilaterian biogenesis components of miRNAs and piRNAs, respectively, resulted in developmental arrest similar to HEN1 morphants. Our findings suggest that HEN1 mediated methylation of sRNAs reflects the ancestral state, where miRNAs were also methylated. Thus, we provide the first evidence of a methylation mechanism that stabilizes miRNAs in animals, and highlight the importance of post-transcriptional regulation in non-bilaterian animals. Plants and animals use small RNAs to regulate gene expression, virus silencing and genomic integrity. These functions depend on specific binding of small RNAs to longer RNA targets. The methyltransferase HEN1 plays a crucial role in stabilizing small RNAs upon their binding to perfectly-matching targets. Lack of methylation in case of a perfect match will lead to small RNA degradation. In general, methylation of microRNAs, a class of small RNAs, is part of their biogenesis in plants, but not in bilaterian animals such as vertebrates, worms and insects, where perfectly-matching microRNA targets are rare. In contrast, in Cnidaria (sea anemones, corals and jellyfish), the sister group to Bilateria, microRNAs frequently bind their targets with a nearly perfect match. In this study, we show that in the cnidarian Nematostella vectensis methylation of microRNAs and other small RNAs is consistent and frequent throughout development and that knockdown of the cnidarian HEN1 results in a developmental arrest. Small RNA sequencing of the treated animals, reveals that small RNAs are depleted and shortened. Therefore, our findings suggest that HEN1-mediated methylation of small RNAs was present in the last common ancestor of Cnidaria and Bilateria 600 million years ago and was responsible for microRNA stabilization.
Collapse
Affiliation(s)
- Vengamanaidu Modepalli
- Department of Ecology, Evolution and Behavior, Alexander Silberman Institute of Life Sciences, Faculty of Science, The Hebrew University of Jerusalem, Jerusalem, Israel
- * E-mail: (VM); (YM)
| | - Arie Fridrich
- Department of Ecology, Evolution and Behavior, Alexander Silberman Institute of Life Sciences, Faculty of Science, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Maayan Agron
- Department of Ecology, Evolution and Behavior, Alexander Silberman Institute of Life Sciences, Faculty of Science, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Yehu Moran
- Department of Ecology, Evolution and Behavior, Alexander Silberman Institute of Life Sciences, Faculty of Science, The Hebrew University of Jerusalem, Jerusalem, Israel
- * E-mail: (VM); (YM)
| |
Collapse
|
4
|
Kirillova A, Genikhovich G, Pukhlyakova E, Demilly A, Kraus Y, Technau U. Germ-layer commitment and axis formation in sea anemone embryonic cell aggregates. Proc Natl Acad Sci U S A 2018; 115:1813-1818. [PMID: 29440382 PMCID: PMC5828576 DOI: 10.1073/pnas.1711516115] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
Robust morphogenetic events are pivotal for animal embryogenesis. However, comparison of the modes of development of different members of a phylum suggests that the spectrum of developmental trajectories accessible for a species might be far broader than can be concluded from the observation of normal development. Here, by using a combination of microsurgery and transgenic reporter gene expression, we show that, facing a new developmental context, the aggregates of dissociated embryonic cells of the sea anemone Nematostella vectensis take an alternative developmental trajectory. The self-organizing aggregates rely on Wnt signals produced by the cells of the original blastopore lip organizer to form body axes but employ morphogenetic events typical for normal development of distantly related cnidarians to re-establish the germ layers. The reaggregated cells show enormous plasticity including the capacity of the ectodermal cells to convert into endoderm. Our results suggest that new developmental trajectories may evolve relatively easily when highly plastic embryonic cells face new constraints.
Collapse
Affiliation(s)
- Anastasia Kirillova
- Department for Molecular Evolution and Development, Center of Organismal Systems Biology, Faculty of Life Sciences, University of Vienna, A-1090 Vienna, Austria
- Department of Evolutionary Biology, Biological Faculty, Moscow State University, 119234 Moscow, Russia
| | - Grigory Genikhovich
- Department for Molecular Evolution and Development, Center of Organismal Systems Biology, Faculty of Life Sciences, University of Vienna, A-1090 Vienna, Austria;
| | - Ekaterina Pukhlyakova
- Department for Molecular Evolution and Development, Center of Organismal Systems Biology, Faculty of Life Sciences, University of Vienna, A-1090 Vienna, Austria
| | - Adrien Demilly
- Department for Molecular Evolution and Development, Center of Organismal Systems Biology, Faculty of Life Sciences, University of Vienna, A-1090 Vienna, Austria
| | - Yulia Kraus
- Department of Evolutionary Biology, Biological Faculty, Moscow State University, 119234 Moscow, Russia;
- Koltzov Institute of Developmental Biology, Russian Academy of Sciences, 119334 Moscow, Russia
| | - Ulrich Technau
- Department for Molecular Evolution and Development, Center of Organismal Systems Biology, Faculty of Life Sciences, University of Vienna, A-1090 Vienna, Austria;
| |
Collapse
|
5
|
Servetnick MD, Steinworth B, Babonis LS, Simmons D, Salinas-Saavedra M, Martindale MQ. Cas9-mediated excision of Nematostella brachyury disrupts endoderm development, pharynx formation and oral-aboral patterning. Development 2017; 144:2951-2960. [PMID: 28705897 PMCID: PMC5592810 DOI: 10.1242/dev.145839] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2016] [Accepted: 07/05/2017] [Indexed: 12/26/2022]
Abstract
The mesoderm is a key novelty in animal evolution, although we understand little of how the mesoderm arose. brachyury, the founding member of the T-box gene family, is a key gene in chordate mesoderm development. However, the brachyury gene was present in the common ancestor of fungi and animals long before mesoderm appeared. To explore ancestral roles of brachyury prior to the evolution of definitive mesoderm, we excised the gene using CRISPR/Cas9 in the diploblastic cnidarian Nematostella vectensis Nvbrachyury is normally expressed in precursors of the pharynx, which separates endoderm from ectoderm. In knockout embryos, the pharynx does not form, embryos fail to elongate, and endoderm organization, ectodermal cell polarity and patterning along the oral-aboral axis are disrupted. Expression of many genes both inside and outside the Nvbrachyury expression domain is affected, including downregulation of Wnt genes at the oral pole. Our results point to an ancient role for brachyury in morphogenesis, cell polarity and the patterning of both ectodermal and endodermal derivatives along the primary body axis.
Collapse
Affiliation(s)
- Marc D Servetnick
- Division of Biological Sciences, University of Washington Bothell, Bothell, WA 98011, USA
| | - Bailey Steinworth
- Whitney Laboratory for Marine Bioscience, University of Florida, St Augustine, FL 32080, USA
| | - Leslie S Babonis
- Whitney Laboratory for Marine Bioscience, University of Florida, St Augustine, FL 32080, USA
| | - David Simmons
- Whitney Laboratory for Marine Bioscience, University of Florida, St Augustine, FL 32080, USA
| | - Miguel Salinas-Saavedra
- Whitney Laboratory for Marine Bioscience, University of Florida, St Augustine, FL 32080, USA
| | - Mark Q Martindale
- Whitney Laboratory for Marine Bioscience, University of Florida, St Augustine, FL 32080, USA
| |
Collapse
|
6
|
Abstract
The startling capacity of the amphibian Spemann organizer to induce naïve cells to form a Siamese twin embryo with a second set of body axes is one of the hallmarks of developmental biology. However, the axis-inducing potential of the blastopore-associated tissue is commonly regarded as a chordate feature. Here we show that the blastopore lip of a non-bilaterian metazoan, the anthozoan cnidarian Nematostella vectensis, possesses the same capacity and uses the same molecular mechanism for inducing extra axes as chordates: Wnt/β-catenin signaling. We also demonstrate that the establishment of the secondary, directive axis in Nematostella by BMP signaling is sensitive to an initial Wnt signal, but once established the directive axis becomes Wnt-independent. By combining molecular analysis with experimental embryology, we provide evidence that the emergence of the Wnt/β-catenin driven blastopore-associated axial organizer predated the cnidarian-bilaterian split over 600 million years ago.
Collapse
Affiliation(s)
- Yulia Kraus
- Department for Molecular Evolution and Development, Centre of Organismal Systems Biology, University of Vienna, Althanstraße 14, Vienna A-1090, Austria
- Department of Evolutionary Biology, Biological Faculty, Moscow State University, Leninskiye gory 1/12, Moscow 119234, Russia
| | - Andy Aman
- Department for Molecular Evolution and Development, Centre of Organismal Systems Biology, University of Vienna, Althanstraße 14, Vienna A-1090, Austria
| | - Ulrich Technau
- Department for Molecular Evolution and Development, Centre of Organismal Systems Biology, University of Vienna, Althanstraße 14, Vienna A-1090, Austria
| | - Grigory Genikhovich
- Department for Molecular Evolution and Development, Centre of Organismal Systems Biology, University of Vienna, Althanstraße 14, Vienna A-1090, Austria
| |
Collapse
|
7
|
Leclère L, Bause M, Sinigaglia C, Steger J, Rentzsch F. Development of the aboral domain in Nematostella requires β-catenin and the opposing activities of Six3/6 and Frizzled5/8. Development 2016; 143:1766-77. [PMID: 26989171 PMCID: PMC4874479 DOI: 10.1242/dev.120931] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2014] [Accepted: 03/08/2016] [Indexed: 01/25/2023]
Abstract
The development of the oral pole in cnidarians and the posterior pole in bilaterians is regulated by canonical Wnt signaling, whereas a set of transcription factors, including Six3/6 and FoxQ2, controls aboral development in cnidarians and anterior identity in bilaterians. However, it is poorly understood how these two patterning systems are initially set up in order to generate correct patterning along the primary body axis. Investigating the early steps of aboral pole formation in the sea anemone Nematostella vectensis, we found that, at blastula stage, oral genes are expressed before aboral genes and that Nvβ-catenin regulates both oral and aboral development. In the oral hemisphere, Nvβ-catenin specifies all subdomains except the oral-most, NvSnailA-expressing domain, which is expanded upon Nvβ-catenin knockdown. In addition, Nvβ-catenin establishes the aboral patterning system by promoting the expression of NvSix3/6 at the aboral pole and suppressing the Wnt receptor NvFrizzled5/8 at the oral pole. NvFrizzled5/8 expression thereby gets restricted to the aboral domain. At gastrula stage, NvSix3/6 and NvFrizzled5/8 are both expressed in the aboral domain, but they have opposing activities, with NvSix3/6 maintaining and NvFrizzled5/8 restricting the size of the aboral domain. At planula stage, NvFrizzled5/8 is required for patterning within the aboral domain and for regulating the size of the apical organ by modulation of a previously characterized FGF feedback loop. Our findings suggest conserved roles for Six3/6 and Frizzled5/8 in aboral/anterior development and reveal key functions for Nvβ-catenin in the patterning of the entire oral-aboral axis of Nematostella.
Collapse
Affiliation(s)
- Lucas Leclère
- Sars Centre for Marine Molecular Biology, University of Bergen, Thormøhlensgt 55, Bergen 5008, Norway Sorbonne Universités, UPMC Univ Paris 06, CNRS, Laboratoire de Biologie du Développement de Villefranche-sur-mer (LBDV), 181 chemin du Lazaret, Villefranche-sur-mer 06230, France
| | - Markus Bause
- Sars Centre for Marine Molecular Biology, University of Bergen, Thormøhlensgt 55, Bergen 5008, Norway
| | - Chiara Sinigaglia
- Sars Centre for Marine Molecular Biology, University of Bergen, Thormøhlensgt 55, Bergen 5008, Norway
| | - Julia Steger
- Sars Centre for Marine Molecular Biology, University of Bergen, Thormøhlensgt 55, Bergen 5008, Norway
| | - Fabian Rentzsch
- Sars Centre for Marine Molecular Biology, University of Bergen, Thormøhlensgt 55, Bergen 5008, Norway
| |
Collapse
|
8
|
Sinigaglia C, Busengdal H, Lerner A, Oliveri P, Rentzsch F. Molecular characterization of the apical organ of the anthozoan Nematostella vectensis. Dev Biol 2015; 398:120-33. [PMID: 25478911 PMCID: PMC4300403 DOI: 10.1016/j.ydbio.2014.11.019] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2014] [Revised: 10/16/2014] [Accepted: 11/13/2014] [Indexed: 02/07/2023]
Abstract
Apical organs are sensory structures present in many marine invertebrate larvae where they are considered to be involved in their settlement, metamorphosis and locomotion. In bilaterians they are characterised by a tuft of long cilia and receptor cells and they are associated with groups of neurons, but their relatively low morphological complexity and dispersed phylogenetic distribution have left their evolutionary relationship unresolved. Moreover, since apical organs are not present in the standard model organisms, their development and function are not well understood. To provide a foundation for a better understanding of this structure we have characterised the molecular composition of the apical organ of the sea anemone Nematostella vectensis. In a microarray-based comparison of the gene expression profiles of planulae with either a wildtype or an experimentally expanded apical organ, we identified 78 evolutionarily conserved genes, which are predominantly or specifically expressed in the apical organ of Nematostella. This gene set comprises signalling molecules, transcription factors, structural and metabolic genes. The majority of these genes, including several conserved, but previously uncharacterized ones, are potentially involved in different aspects of the development or function of the long cilia of the apical organ. To demonstrate the utility of this gene set for comparative analyses, we further analysed the expression of a subset of previously uncharacterized putative orthologs in sea urchin larvae and detected expression for twelve out of eighteen of them in the apical domain. Our study provides a molecular characterization of the apical organ of Nematostella and represents an informative tool for future studies addressing the development, function and evolutionary history of apical organ cells.
Collapse
Affiliation(s)
- Chiara Sinigaglia
- Sars Centre for Marine Molecular Biology, University of Bergen, Thormøhlensgt 55, 5008 Bergen, Norway
| | - Henriette Busengdal
- Sars Centre for Marine Molecular Biology, University of Bergen, Thormøhlensgt 55, 5008 Bergen, Norway
| | - Avi Lerner
- Department of Genetics, Evolution and Environment, University College London, Gower Street, London WC1E 6BT, UK
| | - Paola Oliveri
- Department of Genetics, Evolution and Environment, University College London, Gower Street, London WC1E 6BT, UK
| | - Fabian Rentzsch
- Sars Centre for Marine Molecular Biology, University of Bergen, Thormøhlensgt 55, 5008 Bergen, Norway.
| |
Collapse
|
9
|
Botman D, Röttinger E, Martindale MQ, de Jong J, Kaandorp JA. A computational approach towards a gene regulatory network for the developing Nematostella vectensis gut. PLoS One 2014; 9:e103341. [PMID: 25076223 PMCID: PMC4116165 DOI: 10.1371/journal.pone.0103341] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2014] [Accepted: 06/26/2014] [Indexed: 11/19/2022] Open
Abstract
Background The starlet sea anemone Nematostella vectensis is a diploblastic cnidarian that expresses a set of conserved genes for gut formation during its early development. During the last decade, the spatial distribution of many of these genes has been visualized with RNA hybridization or protein immunolocalization techniques. However, due to N. vectensis' curved and changing morphology, quantification of these spatial data is problematic. A method is developed for two-dimensional gene expression quantification, which enables a numerical analysis and dynamic modeling of these spatial patterns. Methods/Result In this work, first standardized gene expression profiles are generated from publicly available N. vectensis embryo images that display mRNA and/or protein distributions. Then, genes expressed during gut formation are clustered based on their expression profiles, and further grouped based on temporal appearance of their gene products in embryonic development. Representative expression profiles are manually selected from these clusters, and used as input for a simulation-based optimization scheme. This scheme iteratively fits simulated profiles to the selected profiles, leading to an optimized estimation of the model parameters. Finally, a preliminary gene regulatory network is derived from the optimized model parameters. Outlook While the focus of this study is N. vectensis, the approach outlined here is suitable for inferring gene regulatory networks in the embryonic development of any animal, thus allowing to comparatively study gene regulation of gut formation in silico across various species.
Collapse
Affiliation(s)
- Daniel Botman
- Computational Science, University of Amsterdam, Amsterdam, The Netherlands
| | - Eric Röttinger
- Université Nice Sophia Antipolis, Institute for Research on Cancer and Aging, Nice (IRCAN), UMR 7284, Nice, France
- Centre National de la Recherche Scientifique (CNRS), Institute for Research on Cancer and Aging, Nice (IRCAN), UMR 7284, Nice, France
- Institut National de la Santé et de la Recherche Médicale (INSERM), Institute for Research on Cancer and Aging, Nice (IRCAN), U1081, Nice, France
| | - Mark Q. Martindale
- Whitney Lab for Marine Bioscience, University of Florida, St. Augustine, Florida, United States of America
| | - Johann de Jong
- Computational Cancer Biology Group, Division of Molecular Carcinogenesis, The Netherlands Cancer Institute, Amsterdam, the Netherlands
| | - Jaap A. Kaandorp
- Computational Science, University of Amsterdam, Amsterdam, The Netherlands
- * E-mail:
| |
Collapse
|
10
|
Röttinger E, Dahlin P, Martindale MQ. A framework for the establishment of a cnidarian gene regulatory network for "endomesoderm" specification: the inputs of ß-catenin/TCF signaling. PLoS Genet 2012; 8:e1003164. [PMID: 23300467 PMCID: PMC3531958 DOI: 10.1371/journal.pgen.1003164] [Citation(s) in RCA: 88] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2012] [Accepted: 10/27/2012] [Indexed: 12/03/2022] Open
Abstract
Understanding the functional relationship between intracellular factors and
extracellular signals is required for reconstructing gene regulatory networks
(GRN) involved in complex biological processes. One of the best-studied
bilaterian GRNs describes endomesoderm specification and predicts that both
mesoderm and endoderm arose from a common GRN early in animal evolution.
Compelling molecular, genomic, developmental, and evolutionary evidence supports
the hypothesis that the bifunctional gastrodermis of the cnidarian-bilaterian
ancestor is derived from the same evolutionary precursor of both endodermal and
mesodermal germ layers in all other triploblastic bilaterian animals. We have
begun to establish the framework of a provisional cnidarian
“endomesodermal” gene regulatory network in the sea anemone,
Nematostella vectensis, by using a genome-wide microarray
analysis on embryos in which the canonical Wnt/ß-catenin pathway was
ectopically targeted for activation by two distinct pharmaceutical agents
(lithium chloride and 1-azakenpaullone) to identify potential targets of
endomesoderm specification. We characterized 51 endomesodermally expressed
transcription factors and signaling molecule genes (including 18 newly
identified) with fine-scale temporal (qPCR) and spatial (in
situ) analysis to define distinct co-expression domains within the
animal plate of the embryo and clustered genes based on their earliest zygotic
expression. Finally, we determined the input of the canonical
Wnt/ß-catenin pathway into the cnidarian endomesodermal GRN using
morpholino and mRNA overexpression experiments to show that NvTcf/canonical Wnt
signaling is required to pattern both the future endomesodermal and ectodermal
domains prior to gastrulation, and that both BMP and FGF (but not Notch)
pathways play important roles in germ layer specification in this animal. We
show both evolutionary conserved as well as profound differences in
endomesodermal GRN structure compared to bilaterians that may provide
fundamental insight into how GRN subcircuits have been adopted, rewired, or
co-opted in various animal lineages that give rise to specialized endomesodermal
cell types. Cnidarians (anemones, corals, and “jellyfish”) are an animal group
whose adults possess derivatives of only two germ layers: ectoderm and a
bifunctional (absorptive and contractile) gastrodermal (gut) layer. Cnidarians
are the closest living relatives to bilaterally symmetrical animals that possess
all three germ layers (ecto, meso, and endoderm); and compelling molecular,
genomic, developmental, and evolutionary evidence exists to demonstrate that the
cnidarian gastrodermis is evolutionarily related to both endodermal and
mesodermal germ layers in all other triploblastic bilaterian animals. Little is
known about endomesoderm specification in cnidarians. In this study, we
constructed the framework of a cnidarian endomesodermal gene regulatory network
in the sea anemone, Nematostella vectensis, using a combination
of experimental approaches. We identified and characterized by both qPCR and
in situ hybridization 51 genes expressed in defined domains
within the presumptive endomesoderm. In addition, we functionally demonstrate
that Wnt/Tcf signaling is crucial for regionalized expression of a defined
subset of these genes prior to gut formation and endomesoderm maintenance. Our
results support the idea of an ancient gene regulatory network underlying
endomesoderm specification that involves inputs from multiple signaling pathways
(Wnt, FGF, BMP, but not Notch) early in development, that are temporarily
uncoupled in bilaterian animals.
Collapse
Affiliation(s)
- Eric Röttinger
- Kewalo Marine Laboratory, Pacific Biosciences Research Center,
University of Hawai'i, Honolulu, Hawai'i, United States of
America
| | - Paul Dahlin
- Kewalo Marine Laboratory, Pacific Biosciences Research Center,
University of Hawai'i, Honolulu, Hawai'i, United States of
America
| | - Mark Q. Martindale
- Kewalo Marine Laboratory, Pacific Biosciences Research Center,
University of Hawai'i, Honolulu, Hawai'i, United States of
America
- * E-mail:
| |
Collapse
|
11
|
Popova LB, Vornov DA, Kosevich IA, Panchin IV. [Gap junctions in sea anemone, Nematostella vectensis, embryo]. Zh Obshch Biol 2012; 73:83-87. [PMID: 22590904] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Gap junctions (GJs) are composed of membrane proteins that form channels connecting the cytoplasm of adjacent cells and permeable to ions and small molecules. They are considered to be the main or only type of intercellular channels and a universal feature of all multicellular animals (Metazoa). Till recently, sea anemones and corals (Anthozoa, Cnidaria) appeared to be an exception from this rule. There were no structural or physiological data supporting the presence of GJ in Anthozoa. For some time no genes homologous to GJ proteins (connexins or pannexins) were detected in sea anemone Nematostella vectensis (Cnidaria, Anthozoa) or other Anthozoa genomes. Recently, pannexin homolog was found in Nematostella. Our intracellular recordings demonstrate electrical coupling between blastomeres in embryos at the 8-cells stage. At the same time, carboxyfluorescein fluorescent dye did not diffuse between electrically coupled cells, which excludes the possibility that the observed electrical coupling is mediated by incomplete cytoplasm separation during the cleavage. These data support the idea that GJ are ubiquitous for Metazoa, and pannexins are universal GJ proteins.
Collapse
|
12
|
Abstract
Little information is available on the sexual reproductive biology of anemones that provide essential habitat for anemonefish. Here we provide the first information on the surface ultrastructural and morphological changes during development of the embryos and planula larvae of Entacmaea quadricolor and Heteractis crispa, using light and scanning electron microscopy. Newly spawned eggs of E. quadricolor and H. crispa averaged 794 microm and 589 microm diameter, respectively, and were covered by many spires of microvilli that were evenly distributed over the egg surface, except for a single bare patch. Eggs of both species contained abundant zooxanthellae when spawned, indicating vertical transmission of symbionts. Fertilization was external, and the resulting embryos displayed superficial cleavage. As development continued, individual blastomeres became readily distinguishable and a round-to-ovoid blastula was formed, which flattened with further divisions. The edges of the blastula thickened, creating a concave-convex dish-shaped gastrula. The outer margins of the gastrula appeared to roll inward, leading to the formation of an oral pore and a ciliated planula larva. Larval motility and directional movement were first observed 36 h after spawning. E. quadricolor larval survival remained high during the first 4 d after spawning, then decreased rapidly.
Collapse
Affiliation(s)
- Anna Scott
- National Marine Science Centre, PO Box J321, Coffs Harbour, NSW 2450, Australia.
| | | |
Collapse
|
13
|
Lee PN, Kumburegama S, Marlow HQ, Martindale MQ, Wikramanayake AH. Asymmetric developmental potential along the animal–vegetal axis in the anthozoan cnidarian, Nematostella vectensis, is mediated by Dishevelled. Dev Biol 2007; 310:169-86. [PMID: 17716645 DOI: 10.1016/j.ydbio.2007.05.040] [Citation(s) in RCA: 118] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2007] [Revised: 05/21/2007] [Accepted: 05/29/2007] [Indexed: 11/16/2022]
Abstract
The relationship between egg polarity and the adult body plan is well understood in many bilaterians. However, the evolutionary origins of embryonic polarity are not known. Insight into the evolution of polarity will come from understanding the ontogeny of polarity in non-bilaterian forms, such as cnidarians. We examined how the axial properties of the starlet sea anemone, Nematostella vectensis (Anthozoa, Cnidaria), are established during embryogenesis. Egg-cutting experiments and sperm localization show that Nematostella eggs are only fertilized at the animal pole. Vital marking experiments demonstrate that the egg animal pole corresponds to the sites of first cleavage and gastrulation, and the oral pole of the adult. Embryo separation experiments demonstrate an asymmetric segregation of developmental potential along the animal-vegetal axis prior to the 8-cell stage. We demonstrate that Dishevelled (Dsh) plays an important role in mediating this asymmetric segregation of developmental fate. Although NvDsh mRNA is ubiquitously expressed during embryogenesis, the protein is associated with the female pronucleus at the animal pole in the unfertilized egg, becomes associated with the unipolar first cleavage furrow, and remains enriched in animal pole blastomeres. Our results suggest that at least one mechanism for Dsh enrichment at the animal pole is through its degradation at the vegetal pole. Functional studies reveal that NvDsh is required for specifying embryonic polarity and endoderm by stabilizing beta-catenin in the canonical Wnt signaling pathway. The localization of Dsh to the animal pole in Nematostella and two other anthozoan cnidarians (scleractinian corals) provides a possible explanation for how the site of gastrulation has changed in bilaterian evolution while other axial components of development have remained the same and demonstrates that modifications of the Wnt signaling pathway have been used to pattern a wide variety of metazoan embryos.
Collapse
Affiliation(s)
- Patricia N Lee
- Kewalo Marine Lab, Pacific Biosciences Research Center/University of Hawaii, 41 Ahui Street, Honolulu, HI 96813, USA
| | | | | | | | | |
Collapse
|
14
|
Mazza ME, Pang K, Martindale MQ, Finnerty JR. Genomic organization, gene structure, and developmental expression of three clustered otx genes in the sea anemone Nematostella vectensis. J Exp Zool B Mol Dev Evol 2007; 308:494-506. [PMID: 17377951 DOI: 10.1002/jez.b.21158] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Otx homeodomain transcription factors have been studied in a variety of eumetazoan animals where they have roles in anterior neural development, endomesoderm formation, and the formation of larval ciliated fields. Here, we describe the gene structure and developmental expression of three Otx loci in the starlet sea anemone, Nematostella vectensis (phylum Cnidaria; class Anthozoa). Nematostella's three Otx genes (OtxA, OtxB, and OtxC) are located in a compact genomic cluster spanning 63.6 kb. The homeodomains of all three Otx genes are highly similar to their bilaterian counterparts, but only OtxB exhibits the conserved WSP motif that is located downstream of the homeodomain in many Otx proteins. The genomic organization, in concert with phylogenetic analyses, indicates that two tandem duplications occurred in the lineage leading to Nematostella some time after the Cnidaria diverged from the Bilateria. In situ hybridization reveals that otx is initially expressed by invaginating mesendodermal cells in the gastrula. Later, each of the three otx paralogs is expressed in three discrete larval body regions: in the endoderm of the foot or physa, in an endodermal ring surrounding the pharynx, and in the ectoderm of the tentacles. These data suggest that a single otx locus had already acquired diverse developmental functions in the cnidarian-bilaterian ancestor. Furthermore, following two gene duplications in the line leading to Nematostella, there have been only minor alterations in the spatiotemporal expression of the three Otx paralogs. However, the absence of a conserved protein domain in OtxA and OtxC suggests functional evolution of the protein itself.
Collapse
Affiliation(s)
- Maureen E Mazza
- Department of Biology, Boston University, Boston, Massachusetts 02215, USA
| | | | | | | |
Collapse
|
15
|
Fritzenwanker JH, Genikhovich G, Kraus Y, Technau U. Early development and axis specification in the sea anemone Nematostella vectensis. Dev Biol 2007; 310:264-79. [PMID: 17716644 DOI: 10.1016/j.ydbio.2007.07.029] [Citation(s) in RCA: 101] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2007] [Revised: 07/22/2007] [Accepted: 07/23/2007] [Indexed: 11/30/2022]
Abstract
We investigated the early development of the sea anemone Nematostella vectensis, an emerging model system of the Cnidaria. Early cleavage stages are characterized by substantial variability from embryo to embryo, yet invariably lead to the formation of a coeloblastula. The coeloblastula undergoes a series of unusual broad invaginations-evaginations which can be blocked by cell cycle inhibitors suggesting a causal link of the invagination cycles to the synchronized cell divisions. Blastula invagination cycles stop as cell divisions become asynchronous. Marking experiments show a clear correspondence of the animal-vegetal axis of the egg to the oral-aboral axis of the embryo. The animal pole gives rise to the concave side of the blastula and later to the blastopore of the gastrula, and hence the oral pole of the future polyp. Asymmetric distribution of granules in the unfertilized egg suggest an animal-vegetal asymmetry in the egg in addition to the localized position of the pronucleus. To determine whether this asymmetry reflects asymmetrically distributed determinants along the animal-vegetal axis, we carried out blastomere isolations and embryonic divisions at various stages. Our data strongly indicate that normal primary polyps develop only if cellular material from the animal hemisphere is included, whereas the vegetal hemisphere alone is incapable to differentiate an oral pole. Molecular marker analysis suggests that also the correct patterning of the aboral pole depends on signals from the oral half. This suggests that in Nematostella embryos the animal hemisphere contains organizing activity to form a normal polyp.
Collapse
Affiliation(s)
- Jens H Fritzenwanker
- Sars International Centre for Marine Molecular Biology, University of Bergen, Thormøhlensgt. 55, N-5008, Bergen, Norway
| | | | | | | |
Collapse
|
16
|
Abstract
Ctenophores and cnidarians are two metazoan groups that evolved at least 600 Ma, predating the Cambrian explosion. Although both groups are commonly categorized as diploblastic animals without derivatives of the mesodermal germ layer, ctenophores possess definitive contractile "muscle" cells. T-box family transcription factors are an evolutionarily ancient gene family, arising in the common ancestor of metazoans, and have been divided into eight groups in five distinct subfamilies, many of which are involved in the specification of mesodermal as well as ectodermally and endodermally derived structures. Here, we report the cloning and expression of five T-box genes from a ctenophore, Mnemiopsis leidyi. Phylogenetic analyses demonstrated that ctenophores possess members of at least three of the five T-box subfamilies, and expression studies suggested distinct roles of each T-box genes during gastrulation and early organogenesis. Moreover, genome searches of the sea anemone, Nematostella vectensis (anthozoan cnidarian), showed at least 13 T-box genes in Nematostella, which are divided into at least six distinct groups in the same three subfamilies found in ctenophores. Our results from two diploblastic animals indicate that the common ancestor of eumetazoans had a complex set of T-box genes and that two distinct subfamilies might have appeared during triploblastic evolution.
Collapse
Affiliation(s)
- Atsuko Yamada
- Department of Natural History Sciences, Graduate School of Science, Hokkaido University, Kita 10 Nishi 8, Sapporo 060-0810, Japan.
| | | | | | | |
Collapse
|
17
|
Magie CR, Daly M, Martindale MQ. Gastrulation in the cnidarian Nematostella vectensis occurs via invagination not ingression. Dev Biol 2007; 305:483-97. [PMID: 17397821 DOI: 10.1016/j.ydbio.2007.02.044] [Citation(s) in RCA: 86] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2006] [Revised: 02/01/2007] [Accepted: 02/26/2007] [Indexed: 10/23/2022]
Abstract
Gastrulation is a central event in metazoan development, involving many cellular behaviors including invagination, delamination, and ingression. Understanding the cell biology underlying gastrulation in many different taxa will help clarify the evolution of gastrulation mechanisms. Gastrulation in the anthozoan cnidarian Nematostella vectensis has been described as a combination of invagination and unipolar ingression through epithelial to mesenchymal transitions (EMT), possibly controlled by snail genes, important regulators of EMT in other organisms. Our examination, however, fails to reveal evidence of ingressing cells. Rather, we observe that endodermal cells constrict their apices, adopting bottle-like morphologies especially pronounced adjacent to the blastopore lip. They retain apical projections extending to the archenteron throughout gastrulation. Basally, they form actin-rich protrusions, including interdigitating filopodia that may be important in pulling the ectodermal and endodermal cells together. Endodermal cells retain cell-cell junctions while invaginating, and are organized throughout development. Never is the blastocoel filled by a mass of mesenchyme. Additionally, injection of splice-blocking morpholinos to Nematostella snail genes does not result in a phenotype despite dramatically reducing wild-type transcript, and overexpression of Snail-GFP in different clonal domains has no effect on cell behavior. These data indicate that EMT is not a major factor during gastrulation in Nematostella.
Collapse
Affiliation(s)
- Craig R Magie
- Kewalo Marine Laboratory, Pacific Biomedical Research Center, University of Hawai'i Honolulu, HI 96813, USA
| | | | | |
Collapse
|
18
|
Matus DQ, Thomsen GH, Martindale MQ. FGF signaling in gastrulation and neural development in Nematostella vectensis, an anthozoan cnidarian. Dev Genes Evol 2007; 217:137-48. [PMID: 17237944 PMCID: PMC4580332 DOI: 10.1007/s00427-006-0122-3] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2006] [Accepted: 11/03/2006] [Indexed: 11/26/2022]
Abstract
The fibroblast growth factor (FGF) signal transduction pathway serves as one of the key regulators of early metazoan development, displaying conserved roles in the specification of endodermal, mesodermal, and neural fates during vertebrate development. FGF signals also regulate gastrulation, in part, by triggering epithelial to mesenchymal transitions in embryos of both vertebrates and invertebrates. Thus, FGF signals coordinate gastrulation movements across many different phyla. To help understand the breadth of FGF signaling deployment across the animal kingdom, we have examined the presence and expression of genes encoding FGF pathway components in the anthozoan cnidarian Nematostella vectensis. We isolated three FGF ligands (NvFGF8A, NvFGF8B, and NvFGF1A), two FGF receptors (NvFGFRa and NvFGFRb), and two orthologs of vertebrate FGF responsive genes, Sprouty (NvSprouty), an inhibitor of FGF signaling, and Churchill (NvChurchill), a Zn finger transcription factor. We found these FGF ligands, receptors, and response gene expressed asymmetrically along the oral/aboral axis during gastrulation and in a developing chemosensory structure of planula stages known as the apical tuft. These results suggest a conserved role for FGF signaling molecules in coordinating both gastrulation and neural induction that predates the Cambrian explosion and the origins of the Bilateria.
Collapse
Affiliation(s)
- David Q. Matus
- Kewalo Marine Lab, Pacific Bioscience Research Centre, University of Hawai'i, 41 Ahui Street, Honolulu, HI 96813, USA
| | - Gerald H. Thomsen
- Department of Biochemistry and Cell Biology, Center for Developmental Genetics, Stony Brook University, Stony Brook, NY 11794-5215, USA
| | - Mark Q. Martindale
- Kewalo Marine Lab, Pacific Bioscience Research Centre, University of Hawai'i, 41 Ahui Street, Honolulu, HI 96813, USA
| |
Collapse
|
19
|
Matus DQ, Pang K, Marlow H, Dunn CW, Thomsen GH, Martindale MQ. Molecular evidence for deep evolutionary roots of bilaterality in animal development. Proc Natl Acad Sci U S A 2006; 103:11195-200. [PMID: 16837574 PMCID: PMC1544064 DOI: 10.1073/pnas.0601257103] [Citation(s) in RCA: 129] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2006] [Indexed: 11/18/2022] Open
Abstract
Nearly all metazoans show signs of bilaterality, yet it is believed the bilaterians arose from radially symmetric forms hundreds of millions of years ago. Cnidarians (corals, sea anemones, and "jellyfish") diverged from other animals before the radiation of the Bilateria. They are diploblastic and are often characterized as being radially symmetrical around their longitudinal (oral-aboral) axis. We have studied the deployment of orthologs of a number of family members of developmental regulatory genes that are expressed asymmetrically during bilaterian embryogenesis from the sea anemone, Nematostella vectensis. The secreted TGF-beta genes Nv-dpp, Nv-BMP5-8, six TGF-beta antagonists (NvChordin, NvNoggin1, NvNoggin2, NvGremlin, NvFollistatin, and NvFollistatin-like), the homeodomain proteins NvGoosecoid (NvGsc) and NvGbx, and the secreted guidance factor, NvNetrin, were studied. NvDpp, NvChordin, NvNoggin1, NvGsc, and NvNetrin are expressed asymmetrically along the axis perpendicular to the oral-aboral axis, the directive axis. Furthermore, NvGbx, and NvChordin are expressed in restricted domains on the left and right sides of the body, suggesting that the directive axis is homologous with the bilaterian dorsal-ventral axis. The asymmetric expression of NvNoggin1 and NvGsc appear to be maintained by the canonical Wnt signaling pathway. The asymmetric expression of NvNoggin1, NvNetrin, and Hox orthologs NvAnthox7, NvAnthox8, NvAnthox1a, and NvAnthox6, in conjunction with the observation that NvNoggin1 is able to induce a secondary axis in Xenopus embryos argues that N. vectensis could possess antecedents of the organization of the bilaterian central nervous system.
Collapse
Affiliation(s)
- David Q. Matus
- *Kewalo Marine Laboratory, Pacific Bioscience Research Center, University of Hawaii, 41 Ahui Street, Honolulu, HI 96813; and
| | - Kevin Pang
- *Kewalo Marine Laboratory, Pacific Bioscience Research Center, University of Hawaii, 41 Ahui Street, Honolulu, HI 96813; and
| | - Heather Marlow
- *Kewalo Marine Laboratory, Pacific Bioscience Research Center, University of Hawaii, 41 Ahui Street, Honolulu, HI 96813; and
| | - Casey W. Dunn
- *Kewalo Marine Laboratory, Pacific Bioscience Research Center, University of Hawaii, 41 Ahui Street, Honolulu, HI 96813; and
| | - Gerald H. Thomsen
- Department of Biochemistry and Cell Biology, Center for Developmental Genetics, Stony Brook University, Stony Brook, NY 11794-5215
| | - Mark Q. Martindale
- *Kewalo Marine Laboratory, Pacific Bioscience Research Center, University of Hawaii, 41 Ahui Street, Honolulu, HI 96813; and
| |
Collapse
|
20
|
Abstract
Astacin-like metalloproteases are ubiquitous in the animal kingdom but their phylogenetic relationships and ancient functions within the Metazoa are unclear. We have cloned and characterized four astacin-like cDNAs from the marine hydroid Hydractinia echinata and performed a database search for related genes in the draft genome sequence of the sea anemone Nematostella vectensis. These sequences and those of higher animals' astacins were subjected to phylogenetic analysis revealing five clusters within the Eumetazoa. The bone morphogenetic protein-1/tolloid-like astacins were represented in all eumetazoan phyla studied. The meprins were only found in vertebrates and cnidarians. Two clusters were taxon-specific, and one cluster represented astacins, which probably evolved after the split of the Cnidaria. Interestingly, grouping of astacins according to the protease catalytic domain alone resulted in clusters of proteins with similar overall domain architecture. The Hydractinia astacins were expressed in distinct cells during metamorphosis and some also during wound healing. Previously characterized cnidarian astacins also act during development. Based on our phylogeny, however, we propose that the developmental function of most of them is not homologous to the developmental function assigned to higher animals' astacins.
Collapse
Affiliation(s)
- Frank Möhrlen
- Department of Zoology and Martin Ryan Marine Science Institute, National University of Ireland, Galway, Ireland.
| | | | | | | | | |
Collapse
|
21
|
Abstract
The conserved family of Wnt signaling molecules mediates various developmental processes including governing cell fate, proliferation, and polarity. The diverse developmental functions of the Wnt genes in bilaterians have obscured the evolutionary origin of this important signaling pathway. Recent work in the Cnidaria has shown the diversity of Wnt genes, and regulatory components of Wnt signaling, evolved early in metazoan evolution, prior to the divergence of cnidarians and bilaterians. Evidence from Hydra and the sea anemone, Nematostella, demonstrates a role for Wnt signaling in axis formation and patterning, as well as gastrulation and germ-layer specification. In this review, we examine what is currently known about Wnt signaling in cnidarians, and discuss what this group of "simple" animals may reveal about the evolution of Wnt signaling and polarity.
Collapse
Affiliation(s)
- Patricia N Lee
- Kewalo Marine Lab/Pacific Biosciences Research Center, University of Hawaii, 41 Ahui Street, Honolulu, 96813, USA.
| | | | | | | |
Collapse
|
22
|
Matus DQ, Thomsen GH, Martindale MQ. Dorso/ventral genes are asymmetrically expressed and involved in germ-layer demarcation during cnidarian gastrulation. Curr Biol 2006; 16:499-505. [PMID: 16527745 DOI: 10.1016/j.cub.2006.01.052] [Citation(s) in RCA: 93] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2005] [Revised: 01/11/2006] [Accepted: 01/19/2006] [Indexed: 11/28/2022]
Abstract
Cnidarians (corals, sea anemones, hydroids, and jellyfish) are a basal taxon closely related to bilaterally symmetrical animals and have been characterized as diploblastic and as radially symmetrical around their longitudinal axis. We show that some orthologs of key bilaterian dorso/ventral (D/V) patterning genes, including the TGFbeta signaling molecules NvDpp and NvBMP5-8 and their antagonist NvChordin, are initially expressed asymmetrically at the onset of gastrulation in the anthozoan sea anemone Nematostella vectensis. Surprisingly, unlike flies and vertebrates, the TGFbeta ligands and their antagonist are colocalized at the onset of gastrulation but then segregate by germ layer as gastrulation proceeds. TGFbeta ligands, their extracellular enhancer, NvTolloid, and components of their downstream signaling pathway (NvSmad1/5 and NvSmad4) are all coexpressed in presumptive endoderm, indicating that only planar TGFbeta signaling operates at these stages. NvChordin expression forms a boundary between TGFbeta-expressing endodermal cells and aboral ectoderm. Manipulation of nuclear beta-catenin localization affects TGFbeta ligand and antagonist expression, suggesting that the ancestral role of the dpp/chordin antagonism during gastrulation may have been in germ-layer segregation and/or epithelial patterning rather than dorsal/ventral patterning.
Collapse
Affiliation(s)
- David Q Matus
- Kewalo Marine Lab, Pacific Bioscience Research Center, University of Hawaii, 41 Ahui Street, Honolulu, Hawaii 96813, USA
| | | | | |
Collapse
|
23
|
Kraus Y, Technau U. Gastrulation in the sea anemone Nematostella vectensis occurs by invagination and immigration: an ultrastructural study. Dev Genes Evol 2006; 216:119-32. [PMID: 16416137 DOI: 10.1007/s00427-005-0038-3] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2005] [Accepted: 10/17/2005] [Indexed: 12/28/2022]
Abstract
The sea anemone Nematostella vectensis has recently been established as a new model system for the understanding of the evolution of developmental processes. In particular, the evolutionary origin of gastrulation and its molecular regulation are the subject of intense investigation. However, while molecular data are rapidly accumulating, no detailed morphological data exist describing the process of gastrulation. Here, we carried out an ultrastructural study of different stages of gastrulation in Nematostella using transmission electron microscope and scanning electron microscopy techniques. We show that presumptive endodermal cells undergo a change in cell shape, reminiscent of the bottle cells known from vertebrates and several invertebrates. Presumptive endodermal cells organize into a field, the pre-endodermal plate, which undergoes invagination. In parallel, the endodermal cells decrease their apical cell contacts but remain loosely attached to each other. Hence, during early gastrulation they display an incomplete epithelial-mesenchymal transition (EMT). At a late stage of gastrulation, the cells eventually detach and fill the interior of the blastocoel as mesenchymal cells. This shows that gastrulation in Nematostella occurs by a combination of invagination and late immigration involving EMT. The comparison with molecular expression studies suggests that cells expressing snailA undergo EMT and become endodermal, whereas forkhead/brachyury expressing cells at the ectodermal margin of the blastopore retain their epithelial integrity throughout gastrulation.
Collapse
Affiliation(s)
- Yulia Kraus
- Department of Evolutionary Biology, Biological Faculty, Moscow State University, 199992 Moscow, Russia.
| | | |
Collapse
|
24
|
Magie CR, Pang K, Martindale MQ. Genomic inventory and expression of Sox and Fox genes in the cnidarian Nematostella vectensis. Dev Genes Evol 2005; 215:618-30. [PMID: 16193320 DOI: 10.1007/s00427-005-0022-y] [Citation(s) in RCA: 123] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2005] [Accepted: 08/23/2005] [Indexed: 11/25/2022]
Abstract
The Sox and Forkhead (Fox) gene families are comprised of transcription factors that play important roles in a variety of developmental processes, including germ layer specification, gastrulation, cell fate determination, and morphogenesis. Both the Sox and Fox gene families are divided into subgroups based on the amino acid sequence of their respective DNA-binding domains, the high-mobility group (HMG) box (Sox genes) or Forkhead domain (Fox genes). Utilizing the draft genome sequence of the cnidarian Nematostella vectensis, we examined the genomic complement of Sox and Fox genes in this organism to gain insight into the nature of these gene families in a basal metazoan. We identified 14 Sox genes and 15 Fox genes in Nematostella and conducted a Bayesian phylogenetic analysis comparing HMG box and Forkhead domain sequences from Nematostella with diverse taxa. We found that the majority of bilaterian Sox groups have clear Nematostella orthologs, while only a minority of Fox groups are represented, suggesting that the evolutionary pressures driving the diversification of these gene families may be distinct from one another. In addition, we examined the expression of a subset of these genes during development in Nematostella and found that some of these genes are expressed in patterns consistent with roles in germ layer specification and the regulation of cellular behaviors important for gastrulation. The diversity of expression patterns among members of these gene families in Nematostella reinforces the notion that despite their relatively simple morphology, cnidarians possess much of the molecular complexity observed in bilaterian taxa.
Collapse
Affiliation(s)
- Craig R Magie
- Kewalo Marine Laboratory, Pacific Biomedical Research Center, University of Hawai'i, Honolulu, HI 96813, USA
| | | | | |
Collapse
|
25
|
Extavour CG, Pang K, Matus DQ, Martindale MQ. vasa and nanos expression patterns in a sea anemone and the evolution of bilaterian germ cell specification mechanisms. Evol Dev 2005; 7:201-15. [PMID: 15876193 DOI: 10.1111/j.1525-142x.2005.05023.x] [Citation(s) in RCA: 113] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Most bilaterians specify primordial germ cells (PGCs) during early embryogenesis using either inherited cytoplasmic germ line determinants (preformation) or induction of germ cell fate through signaling pathways (epigenesis). However, data from nonbilaterian animals suggest that ancestral metazoans may have specified germ cells very differently from most extant bilaterians. Cnidarians and sponges have been reported to generate germ cells continuously throughout reproductive life, but previous studies on members of these basal phyla have not examined embryonic germ cell origin. To try to define the embryonic origin of PGCs in the sea anemone Nematostella vectensis, we examined the expression of members of the vasa and nanos gene families, which are critical genes in bilaterian germ cell specification and development. We found that vasa and nanos family genes are expressed not only in presumptive PGCs late in embryonic development, but also in multiple somatic cell types during early embryogenesis. These results suggest one way in which preformation in germ cell development might have evolved from the ancestral epigenetic mechanism that was probably used by a metazoan ancestor.
Collapse
Affiliation(s)
- Cassandra G Extavour
- Laboratory for Development and Evolution, Department of Zoology, University of Cambridge, Cambridge, UK.
| | | | | | | |
Collapse
|
26
|
Fritzenwanker JH, Saina M, Technau U. Analysis of forkhead and snail expression reveals epithelial-mesenchymal transitions during embryonic and larval development of Nematostella vectensis. Dev Biol 2005; 275:389-402. [PMID: 15501226 DOI: 10.1016/j.ydbio.2004.08.014] [Citation(s) in RCA: 128] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2004] [Revised: 08/10/2004] [Accepted: 08/12/2004] [Indexed: 01/15/2023]
Abstract
The winged helix transcription factor Forkhead and the zinc finger transcription factor Snail are crucially involved in germ layer formation in Bilateria. Here, we isolated and characterized a homolog of forkhead/HNF3 (FoxA/group 1) and of snail from a diploblast, the sea anemone Nematostella vectensis. We show that Nematostella forkhead expression starts during late Blastula stage in a ring of cells that demarcate the blastopore margin during early gastrulation, thereby marking the boundary between ectodermal and endodermal tissue. snail, by contrast, is expressed in a complementary pattern in the center of forkhead-expressing cells marking the presumptive endodermal cells fated to ingress during gastrulation. In a significant portion of early gastrulating embryos, forkhead is expressed asymmetrically around the blastopore. While snail-expressing cells form the endodermal cell mass, forkhead marks the pharynx anlage throughout embryonic and larval development. In the primary polyp, forkhead remains expressed in the pharynx. The detailed analysis of forkhead and snail expression during Nematostella embryonic and larval development further suggests that endoderm formation results from epithelial invagination, mesenchymal immigration, and reorganization of the endodermal epithelial layer, that is, by epithelial-mesenchymal transitions (EMT) in combination with extensive morphogenetic movements. snail also governs EMT at different processes during embryonic development in Bilateria. Our data indicate that the function of snail in Diploblasts is to regulate motility and cell adhesion, supporting that the triggering of changes in cell behavior is the ancestral role of snail in Metazoa.
Collapse
Affiliation(s)
- Jens H Fritzenwanker
- Molecular Cell Biology, Institute for Zoology, Darmstadt University of Technology, 64287 Darmstadt, Germany
| | | | | |
Collapse
|
27
|
Kusserow A, Pang K, Sturm C, Hrouda M, Lentfer J, Schmidt HA, Technau U, von Haeseler A, Hobmayer B, Martindale MQ, Holstein TW. Unexpected complexity of the Wnt gene family in a sea anemone. Nature 2005; 433:156-60. [PMID: 15650739 DOI: 10.1038/nature03158] [Citation(s) in RCA: 416] [Impact Index Per Article: 21.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2004] [Accepted: 11/01/2004] [Indexed: 11/08/2022]
Abstract
The Wnt gene family encodes secreted signalling molecules that control cell fate in animal development and human diseases. Despite its significance, the evolution of this metazoan-specific protein family is unclear. In vertebrates, twelve Wnt subfamilies were defined, of which only six have counterparts in Ecdysozoa (for example, Drosophila and Caenorhabditis). Here, we report the isolation of twelve Wnt genes from the sea anemone Nematostella vectensis, a species representing the basal group within cnidarians. Cnidarians are diploblastic animals and the sister-group to bilaterian metazoans. Phylogenetic analyses of N. vectensis Wnt genes reveal a thus far unpredicted ancestral diversity within the Wnt family. Cnidarians and bilaterians have at least eleven of the twelve known Wnt gene subfamilies in common; five subfamilies appear to be lost in the protostome lineage. Expression patterns of Wnt genes during N. vectensis embryogenesis indicate distinct roles of Wnts in gastrulation, resulting in serial overlapping expression domains along the primary axis of the planula larva. This unexpectedly complex inventory of Wnt family signalling factors evolved in early multi-cellular animals about 650 million years (Myr) ago, predating the Cambrian explosion by at least 100 Myr (refs 5, 8). It emphasizes the crucial function of Wnt genes in the diversification of eumetazoan body plans.
Collapse
Affiliation(s)
- Arne Kusserow
- Institute of Zoology, Darmstadt University of Technology, Schnittspahnstrasse 10, D-64287 Darmstadt, Germany
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
28
|
|
29
|
Affiliation(s)
- Peter Holland
- Department of Zoology, University of Oxford, Oxford, OX1 3PS, UK.
| |
Collapse
|
30
|
Abstract
Over 99% of modern animals are members of the evolutionary lineage Bilateria. The evolutionary success of Bilateria is credited partly to the origin of bilateral symmetry. Although animals of the phylum Cnidaria are not within the Bilateria, some representatives, such as the sea anemone Nematostella vectensis, exhibit bilateral symmetry. We show that Nematostella uses homologous genes to achieve bilateral symmetry: Multiple Hox genes are expressed in a staggered fashion along its primary body axis, and the transforming growth factor-beta gene decapentaplegic (dpp) is expressed in an asymmetric fashion about its secondary body axis. These data suggest that bilateral symmetry arose before the evolutionary split of Cnidaria and Bilateria.
Collapse
Affiliation(s)
- John R Finnerty
- Department of Biology, Boston University, 5 Cummington Street, Boston, MA 02215, USA
| | | | | | | | | |
Collapse
|
31
|
Martindale MQ, Pang K, Finnerty JR. Investigating the origins of triploblasty: `mesodermal' gene expression in a diploblastic animal, the sea anemone Nematostella vectensis(phylum, Cnidaria; class, Anthozoa). Development 2004; 131:2463-74. [PMID: 15128674 DOI: 10.1242/dev.01119] [Citation(s) in RCA: 321] [Impact Index Per Article: 16.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Mesoderm played a crucial role in the radiation of the triploblastic Bilateria, permitting the evolution of larger and more complex body plans than in the diploblastic, non-bilaterian animals. The sea anemone Nematostella is a non-bilaterian animal, a member of the phylum Cnidaria. The phylum Cnidaria (sea anemones, corals, hydras and jellyfish) is the likely sister group of the triploblastic Bilateria. Cnidarians are generally regarded as diploblastic animals, possessing endoderm and ectoderm,but lacking mesoderm. To investigate the origin of triploblasty, we studied the developmental expression of seven genes from Nematostella whose bilaterian homologs are implicated in mesodermal specification and the differentiation of mesodermal cell types (twist, snailA, snailB, forkhead,mef2, a GATA transcription factor and a LIMtranscription factor). Except for mef2, the expression of these genes is largely restricted to the endodermal layer, the gastrodermis. mef2is restricted to the ectoderm. The temporal and spatial expression of these`mesoderm' genes suggests that they may play a role in germ layer specification. Furthermore, the predominantly endodermal expression of these genes reinforces the hypothesis that the mesoderm and endoderm of triploblastic animals could be derived from the endoderm of a diploblastic ancestor. Alternatively, we consider the possibility that the diploblastic condition of cnidarians is a secondary simplification, derived from an ancestral condition of triploblasty.
Collapse
Affiliation(s)
- Mark Q Martindale
- Kewalo Marine Laboratory, Pacific Biomedical Research Center, University of Hawaii, 41 Ahui Street, Honolulu, HI 96813, USA.
| | | | | |
Collapse
|
32
|
Davy SK, Turner JR. Early development and acquisition of Zooxanthellae in the temperate symbiotic sea anemone Anthopleura ballii (Cocks). Biol Bull 2003; 205:66-72. [PMID: 12917223 DOI: 10.2307/1543446] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
The ova of Anthopleura ballii become infected with zooxanthellae (endosymbiotic dinoflagellates) of maternal origin just prior to spawning. After fertilization, the zygotes undergo radial, holoblastic cleavage, and then gastrulate by invagination to form ciliated planulae. Because the zooxanthellae are localized on one side of the ovum-and later, within the blastomeres at one end of the embryo-invagination leads to the zooxanthellae being restricted to the planular endoderm and hence to the gastrodermal cells of the adult anemone. We propose that maternal inheritance of zooxanthellae plays an important part in the success of these temperate sea anemones, which live in regions where potential sources of zooxanthellae are scarce.
Collapse
Affiliation(s)
- Simon K Davy
- Institute of Marine Studies, University of Plymouth, Drake Circus, Plymouth PL4 8AA, UK
| | | |
Collapse
|
33
|
Doumenc MD, Levi P. [New interpretation of the symmetry of Cereus pedunculatus (Actiniaria) during embryonic development]. C R Acad Hebd Seances Acad Sci D 1975; 281:1983-6. [PMID: 4231] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
A spatial reconstitution is used to determine with precision the relative position of pharynx and mesenteries during the embryonic development of Cereus pedunculatus. Three successive stages are described for embryonic symmetrisation.
Collapse
|