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Janssen R, Budd GE. New insights into mesoderm and endoderm development, and the nature of the onychophoran blastopore. Front Zool 2024; 21:2. [PMID: 38267986 PMCID: PMC10809584 DOI: 10.1186/s12983-024-00521-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2023] [Accepted: 01/09/2024] [Indexed: 01/26/2024] Open
Abstract
BACKGROUND Early during onychophoran development and prior to the formation of the germ band, a posterior tissue thickening forms the posterior pit. Anterior to this thickening forms a groove, the embryonic slit, that marks the anterior-posterior orientation of the developing embryo. This slit is by some authors considered the blastopore, and thus the origin of the endoderm, while others argue that the posterior pit represents the blastopore. This controversy is of evolutionary significance because if the slit represents the blastopore, then this would support the amphistomy hypothesis that suggests that a slit-like blastopore in the bilaterian ancestor evolved into protostomy and deuterostomy. RESULTS In this paper, we summarize our current knowledge about endoderm and mesoderm development in onychophorans and provide additional data on early endoderm- and mesoderm-determining marker genes such as Blimp, Mox, and the T-box genes. CONCLUSION We come to the conclusion that the endoderm of onychophorans forms prior to the development of the embryonic slit, and thus that the slit is not the primary origin of the endoderm. It is thus unlikely that the embryonic slit represents the blastopore. We suggest instead that the posterior pit indeed represents the lips of the blastopore, and that the embryonic slit (and surrounding tissue) represents a morphologically superficial archenteron-like structure. We conclude further that both endoderm and mesoderm development are under control of conserved gene regulatory networks, and that many of the features found in arthropods including the model Drosophila melanogaster are likely derived.
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Affiliation(s)
- Ralf Janssen
- Department of Earth Sciences, Palaeobiology, Uppsala University, Villavägen 16, 75236, Uppsala, Sweden.
| | - Graham E Budd
- Department of Earth Sciences, Palaeobiology, Uppsala University, Villavägen 16, 75236, Uppsala, Sweden
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Pickett CJ, Gruner HN, Davidson B. Lhx3/4 initiates a cardiopharyngeal-specific transcriptional program in response to widespread FGF signaling. PLoS Biol 2024; 22:e3002169. [PMID: 38271304 PMCID: PMC10810493 DOI: 10.1371/journal.pbio.3002169] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2023] [Accepted: 12/21/2023] [Indexed: 01/27/2024] Open
Abstract
Individual signaling pathways, such as fibroblast growth factors (FGFs), can regulate a plethora of inductive events. According to current paradigms, signal-dependent transcription factors (TFs), such as FGF/MapK-activated Ets family factors, partner with lineage-determining factors to achieve regulatory specificity. However, many aspects of this model have not been rigorously investigated. One key question relates to whether lineage-determining factors dictate lineage-specific responses to inductive signals or facilitate these responses in collaboration with other inputs. We utilize the chordate model Ciona robusta to investigate mechanisms generating lineage-specific induction. Previous studies in C. robusta have shown that cardiopharyngeal progenitor cells are specified through the combined activity of FGF-activated Ets1/2.b and an inferred ATTA-binding transcriptional cofactor. Here, we show that the homeobox TF Lhx3/4 serves as the lineage-determining TF that dictates cardiopharyngeal-specific transcription in response to pleiotropic FGF signaling. Targeted knockdown of Lhx3/4 leads to loss of cardiopharyngeal gene expression. Strikingly, ectopic expression of Lhx3/4 in a neuroectodermal lineage subject to FGF-dependent specification leads to ectopic cardiopharyngeal gene expression in this lineage. Furthermore, ectopic Lhx3/4 expression disrupts neural plate morphogenesis, generating aberrant cell behaviors associated with execution of incompatible morphogenetic programs. Based on these findings, we propose that combinatorial regulation by signal-dependent and lineage-determinant factors represents a generalizable, previously uncategorized regulatory subcircuit we term "cofactor-dependent induction." Integration of this subcircuit into theoretical models will facilitate accurate predictions regarding the impact of gene regulatory network rewiring on evolutionary diversification and disease ontogeny.
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Affiliation(s)
- C. J. Pickett
- Department of Biology, Swarthmore College, Swarthmore, Pennsylvania, United States of America
| | - Hannah N. Gruner
- Department of Biology, Swarthmore College, Swarthmore, Pennsylvania, United States of America
| | - Bradley Davidson
- Department of Biology, Swarthmore College, Swarthmore, Pennsylvania, United States of America
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Sumner JT, Andrasz CL, Johnson CA, Wax S, Anderson P, Keeling EL, Davidson JM. De novo genome assembly and comparative genomics for the colonial ascidian Botrylloides violaceus. G3 (BETHESDA, MD.) 2023; 13:jkad181. [PMID: 37555394 PMCID: PMC10542563 DOI: 10.1093/g3journal/jkad181] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/25/2023] [Revised: 01/25/2023] [Accepted: 07/12/2023] [Indexed: 08/10/2023]
Abstract
Ascidians have the potential to reveal fundamental biological insights related to coloniality, regeneration, immune function, and the evolution of these traits. This study implements a hybrid assembly technique to produce a genome assembly and annotation for the botryllid ascidian, Botrylloides violaceus. A hybrid genome assembly was produced using Illumina, Inc. short and Oxford Nanopore Technologies long-read sequencing technologies. The resulting assembly is comprised of 831 contigs, has a total length of 121 Mbp, N50 of 1 Mbp, and a BUSCO score of 96.1%. Genome annotation identified 13 K protein-coding genes. Comparative genomic analysis with other tunicates reveals patterns of conservation and divergence within orthologous gene families even among closely related species. Characterization of the Wnt gene family, encoding signaling ligands involved in development and regeneration, reveals conserved patterns of subfamily presence and gene copy number among botryllids. This supports the use of genomic data from nonmodel organisms in the investigation of biological phenomena.
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Affiliation(s)
- Jack T Sumner
- Department of Biological Sciences, California Polytechnic State University, San Luis Obispo, CA 93407, USA
| | - Cassidy L Andrasz
- Department of Biological Sciences, California Polytechnic State University, San Luis Obispo, CA 93407, USA
| | - Christine A Johnson
- Department of Biological Sciences, California Polytechnic State University, San Luis Obispo, CA 93407, USA
| | - Sarah Wax
- Department of Biological Sciences, California Polytechnic State University, San Luis Obispo, CA 93407, USA
| | - Paul Anderson
- Department of Computer Science and Software Engineering, California Polytechnic State University, San Luis Obispo, CA 93407, USA
| | - Elena L Keeling
- Department of Biological Sciences, California Polytechnic State University, San Luis Obispo, CA 93407, USA
| | - Jean M Davidson
- Department of Biological Sciences, California Polytechnic State University, San Luis Obispo, CA 93407, USA
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Murphy P, Armit C, Hill B, Venkataraman S, Frankel P, Baldock RA, Davidson DR. Integrated analysis of Wnt signalling system component gene expression. Development 2022; 149:276001. [PMID: 35831952 PMCID: PMC9481969 DOI: 10.1242/dev.200312] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2022] [Accepted: 07/06/2022] [Indexed: 11/20/2022]
Abstract
Wnt signalling controls patterning and differentiation across many tissues and organs of the developing embryo through temporally and spatially restricted expression of multi-gene families encoding ligands, receptors, pathway modulators and intracellular components. Here, we report an integrated analysis of key genes in the 3D space of the mouse embryo across multiple stages of development. We applied a method for 3D/3D image transformation to map all gene expression patterns to a single reference embryo for each stage, providing both visual analysis and volumetric mapping allowing computational methods to interrogate the combined expression patterns. We identify territories where multiple Wnt and Fzd genes are co-expressed and cross-compare all patterns, including all seven Wnt paralogous gene pairs. The comprehensive analysis revealed regions in the embryo where no Wnt or Fzd gene expression is detected, and where single Wnt genes are uniquely expressed. This work provides insight into a previously unappreciated level of organisation of expression patterns, as well as presenting a resource that can be utilised further by the research community for whole-system analysis. Summary: A systematic analysis of integrated expression patterns of Wnt signalling pathway component-encoding genes and canonical pathway read-out, spatially mapped in 3D to mouse embryo models identifies co-expression territories.
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Affiliation(s)
- Paula Murphy
- School of Natural Sciences, Department of Zoology, Trinity College Dublin, The University of Dublin 1 , Dublin 2 , Ireland
| | - Chris Armit
- Institute of Cancer and Genetics, University of Edinburgh 2 MRC Human Genetics Unit , , Crewe Road, Edinburgh EH4 2XU , UK
| | - Bill Hill
- Institute of Cancer and Genetics, University of Edinburgh 2 MRC Human Genetics Unit , , Crewe Road, Edinburgh EH4 2XU , UK
| | - Shanmugasundaram Venkataraman
- Institute of Cancer and Genetics, University of Edinburgh 2 MRC Human Genetics Unit , , Crewe Road, Edinburgh EH4 2XU , UK
| | - Patrick Frankel
- School of Natural Sciences, Department of Zoology, Trinity College Dublin, The University of Dublin 1 , Dublin 2 , Ireland
| | - Richard A. Baldock
- Institute of Cancer and Genetics, University of Edinburgh 2 MRC Human Genetics Unit , , Crewe Road, Edinburgh EH4 2XU , UK
| | - Duncan R. Davidson
- Institute of Cancer and Genetics, University of Edinburgh 2 MRC Human Genetics Unit , , Crewe Road, Edinburgh EH4 2XU , UK
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Onuma TA, Nishida H. Developmental biology of the larvacean Oikopleura dioica: Genome resources, functional screening, and imaging. Dev Growth Differ 2021; 64:67-82. [PMID: 34964127 DOI: 10.1111/dgd.12769] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2021] [Revised: 12/13/2021] [Accepted: 12/13/2021] [Indexed: 12/01/2022]
Abstract
The larvacean Oikopleura dioica is a cosmopolitan planktonic chordate and is closely related to vertebrates. It is characterized by a tadpole-shaped morphology with notochord flanked by muscle in the tail and brain on the dorsal side, a short life cycle of five days, a compact genome of approximately 56 Mb, a simple and transparent body with a small number of cells (~4000 in functional juveniles), invariant embryonic cell lineages, and fast development that ensures complete morphogenesis and organ formation 10 h after fertilization. With these features, this marine chordate is a promising and advantageous animal model in which genetic manipulation is feasible. In this review, we introduce relevant resources and modern techniques that have been developed: (1) Genome and transcriptomes. Oikopleura dioica has the smallest genome among non-parasitic metazoans. Its genome databases have been generated using three geographically distant O. dioica populations, and several intra-species sequence differences are becoming evident; (2) Functional genetic knockdown techniques. Comprehensive screening of genes is feasible using ovarian microinjection and double-strand DNA-induced gene knockdown; and (3) Live imaging of embryos and larvae. Application of these techniques has uncovered novel aspects of development, including meiotic cell arrest, left-right patterning, epidermal cell patterning, and mouth formation involving the connection of ectoderm and endoderm sheets. Oikopleura dioca has become very useful for developmental and evolutionary studies in chordates.
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Affiliation(s)
- Takeshi A Onuma
- Graduate School of Science and Engineering, Faculty of Science, Kagoshima University, Kagoshima, Japan.,Department of Biological Sciences, Graduate School of Science, Osaka University, Toyonaka, Japan
| | - Hiroki Nishida
- Department of Biological Sciences, Graduate School of Science, Osaka University, Toyonaka, Japan
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Janssen R, Pechmann M, Turetzek N. A chelicerate Wnt gene expression atlas: novel insights into the complexity of arthropod Wnt-patterning. EvoDevo 2021; 12:12. [PMID: 34753512 PMCID: PMC8579682 DOI: 10.1186/s13227-021-00182-1] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2021] [Accepted: 10/27/2021] [Indexed: 11/24/2022] Open
Abstract
The Wnt genes represent a large family of secreted glycoprotein ligands that date back to early animal evolution. Multiple duplication events generated a set of 13 Wnt families of which 12 are preserved in protostomes. Embryonic Wnt expression patterns (Wnt-patterning) are complex, representing the plentitude of functions these genes play during development. Here, we comprehensively investigated the embryonic expression patterns of Wnt genes from three species of spiders covering both main groups of true spiders, Haplogynae and Entelegynae, a mygalomorph species (tarantula), as well as a distantly related chelicerate outgroup species, the harvestman Phalangium opilio. All spiders possess the same ten classes of Wnt genes, but retained partially different sets of duplicated Wnt genes after whole genome duplication, some of which representing impressive examples of sub- and neo-functionalization. The harvestman, however, possesses a more complete set of 11 Wnt genes but with no duplicates. Our comprehensive data-analysis suggests a high degree of complexity and evolutionary flexibility of Wnt-patterning likely providing a firm network of mutational protection. We discuss the new data on Wnt gene expression in terms of their potential function in segmentation, posterior elongation, and appendage development and critically review previous research on these topics. We conclude that earlier research may have suffered from the absence of comprehensive gene expression data leading to partial misconceptions about the roles of Wnt genes in development and evolution.
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Affiliation(s)
- Ralf Janssen
- Department of Earth Sciences, Palaeobiology, Uppsala University, Villavägen 16, 75236, Uppsala, Sweden.
| | - Matthias Pechmann
- Department of Developmental Biology, Biocenter, Institute for Zoology, University of Cologne, Zuelpicher Str. 47b, 50674, Cologne, Germany
| | - Natascha Turetzek
- Evolutionary Ecology, Faculty of Biology, Ludwig-Maximilians Universität München, Grosshaderner Strasse 2, 82152, Biozentrum, Germany
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Nishida H, Matsuo M, Konishi S, Ohno N, Manni L, Onuma TA. Germline development during embryogenesis of the larvacean, Oikopleura dioica. Dev Biol 2021; 481:188-200. [PMID: 34755656 DOI: 10.1016/j.ydbio.2021.10.009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2021] [Revised: 10/08/2021] [Accepted: 10/24/2021] [Indexed: 11/18/2022]
Abstract
Germ cells develop into eggs and sperms and represent a lineage that survives through multiple generations. Germ cell specification during embryogenesis proceeds through one of two basic modes: either the cell-autonomous mode or the inductive mode. In the cell-autonomous mode, specification of germ cell fate involves asymmetric partitioning of the specialized maternal cytoplasm, known as the germplasm. Oikopleura dioica is a larvacean (class Appendicularia) and a chordate. It is regarded as a promising animal model for studying chordate development because of its short life cycle (5 days) and small genome size (∼60 Mb). We show that their embryos possess germplasm, as observed in ascidians (class Ascidiacea). The vegetal cytoplasm shifted towards the future posterior pole before the first cleavage occurred. A bilateral pair of primordial germ cells (PGC, B11 cells) was formed at the posterior pole at the 32-cell stage through two rounds of unequal cleavage. These B11 cells did not undergo further division before hatching of the tadpole-shaped larvae. The centrosome-attracting body (CAB) is a subcellular structure that contains the germplasm and plays crucial roles in germ cell development in ascidians. The presence of CAB with germplasm was observed in the germline lineage cells of larvaceans via electron microscopy and using extracted embryos. The CAB appeared at the 8-cell stage and persisted until the middle stage of embryogenesis. The antigen for the phosphorylated histone 3 antibody was localized to the CAB and persisted in the PGC until hatching after the CAB disappeared. Maternal snail mRNA, which encodes a transcription factor, was co-localized with the antigen for the H3S28p antibody. Furthermore, we found a novel PGC-specific subcellular structure that we call the germ body (GB). This study thus highlights the conserved and non-conserved features of germline development between ascidians and larvaceans. The rapid development and short life cycle (five days) of O. dioica would open the way to genetically analyze germ cell development in the future.
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Affiliation(s)
- Hiroki Nishida
- Department of Biological Sciences, Graduate School of Science, Osaka University, Toyonaka, Osaka, 560-0043, Japan.
| | - Masaki Matsuo
- Department of Biological Sciences, Graduate School of Science, Osaka University, Toyonaka, Osaka, 560-0043, Japan
| | - Shohei Konishi
- Department of Biological Sciences, Graduate School of Science, Osaka University, Toyonaka, Osaka, 560-0043, Japan
| | - Nobuhiko Ohno
- Division of Ultrastructural Research, National Institute for Physiological Sciences, Okazaki, 444-8787, Japan; Division of Histology and Cell Biology, Department of Anatomy, Jichi Medical University, Shimotsuke, Tochigi, 329-0498, Japan
| | - Lucia Manni
- Dipartimento di Biologia, Università degli Studi di Padova, via U. Bassi 58/B, I-35121, Padova, Italy
| | - Takeshi A Onuma
- Department of Biological Sciences, Graduate School of Science, Osaka University, Toyonaka, Osaka, 560-0043, Japan
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