1
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Huan P, Liu B. The gastropod Lottia peitaihoensis as a model to study the body patterning of trochophore larvae. Evol Dev 2024; 26:e12456. [PMID: 37667429 DOI: 10.1111/ede.12456] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2023] [Revised: 07/03/2023] [Accepted: 08/18/2023] [Indexed: 09/06/2023]
Abstract
The body patterning of trochophore larvae is important for understanding spiralian evolution and the origin of the bilateral body plan. However, considerable variations are observed among spiralian lineages, which have adopted varied strategies to develop trochophore larvae or even omit a trochophore stage. Some spiralians, such as patellogastropod mollusks, are suggested to exhibit ancestral traits by producing equal-cleaving fertilized eggs and possessing "typical" trochophore larvae. In recent years, we developed a potential model system using the patellogastropod Lottia peitaihoensis (= Lottia goshimai). Here, we introduce how the species were selected and establish sources and techniques, including gene knockdown, ectopic gene expression, and genome editing. Investigations on this species reveal essential aspects of trochophore body patterning, including organizer signaling, molecular and cellular processes connecting the various developmental functions of the organizer, the specification and behaviors of the endomesoderm and ectomesoderm, and the characteristic dorsoventral decoupling of Hox expression. These findings enrich the knowledge of trochophore body patterning and have important implications regarding the evolution of spiralians as well as bilateral body plans.
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Affiliation(s)
- Pin Huan
- CAS and Shandong Province Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Baozhong Liu
- CAS and Shandong Province Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, China
- University of Chinese Academy of Sciences, Beijing, China
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2
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Webster NB, Meyer NP. Capitella teleta gets left out: possible evolutionary shift causes loss of left tissues rather than increased neural tissue from dominant-negative BMPR1. Neural Dev 2024; 19:4. [PMID: 38698415 PMCID: PMC11067212 DOI: 10.1186/s13064-024-00181-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2023] [Accepted: 03/20/2024] [Indexed: 05/05/2024] Open
Abstract
BACKGROUND The evolution of central nervous systems (CNSs) is a fascinating and complex topic; further work is needed to understand the genetic and developmental homology between organisms with a CNS. Research into a limited number of species suggests that CNSs may be homologous across Bilateria. This hypothesis is based in part on similar functions of BMP signaling in establishing fates along the dorsal-ventral (D-V) axis, including limiting neural specification to one ectodermal region. From an evolutionary-developmental perspective, the best way to understand a system is to explore it in a wide range of organisms to create a full picture. METHODS Here, we expand our understanding of BMP signaling in Spiralia, the third major clade of bilaterians, by examining phenotypes after expression of a dominant-negative BMP Receptor 1 and after knock-down of the putative BMP antagonist Chordin-like using CRISPR/Cas9 gene editing in the annelid Capitella teleta (Pleistoannelida). RESULTS Ectopic expression of the dominant-negative Ct-BMPR1 did not increase CNS tissue or alter overall D-V axis formation in the trunk. Instead, we observed a unique asymmetrical phenotype: a distinct loss of left tissues, including the left eye, brain, foregut, and trunk mesoderm. Adding ectopic BMP4 early during cleavage stages reversed the dominant-negative Ct-BMPR1 phenotype, leading to a similar loss or reduction of right tissues instead. Surprisingly, a similar asymmetrical loss of left tissues was evident from CRISPR knock-down of Ct-Chordin-like but concentrated in the trunk rather than the episphere. CONCLUSIONS Our data highlight a novel asymmetrical phenotype, giving us further insight into the complicated story of BMP's developmental role. We further solidify the hypothesis that the function of BMP signaling during the establishment of the D-V axis and CNS is fundamentally different in at least Pleistoannelida, possibly in Spiralia, and is not required for nervous system delimitation in this group.
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Affiliation(s)
- Nicole B Webster
- Biology Department, Clark University, 950 Main Street, Worcester, MA, 01610, USA
- Biology Department, University of Saskatchewan, 112 Science Place, Saskatoon, SK, S7N 5C8, Canada
| | - Néva P Meyer
- Biology Department, Clark University, 950 Main Street, Worcester, MA, 01610, USA.
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3
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Truchado-García M, Perry KJ, Cavodeassi F, Kenny NJ, Henry JQ, Grande C. A Small Change With a Twist Ending: A Single Residue in EGF-CFC Drives Bilaterian Asymmetry. Mol Biol Evol 2022; 40:6947033. [PMID: 36537201 PMCID: PMC9907556 DOI: 10.1093/molbev/msac270] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2022] [Revised: 11/28/2022] [Accepted: 12/05/2022] [Indexed: 12/24/2022] Open
Abstract
Asymmetries are essential for proper organization and function of organ systems. Genetic studies in bilaterians have shown signaling through the Nodal/Smad2 pathway plays a key, conserved role in the establishment of body asymmetries. Although the main molecular players in the network for the establishment of left-right asymmetry (LRA) have been deeply described in deuterostomes, little is known about the regulation of Nodal signaling in spiralians. Here, we identified orthologs of the egf-cfc gene, a master regulator of the Nodal pathway in vertebrates, in several invertebrate species, which includes the first evidence of its presence in non-deuterostomes. Our functional experiments indicate that despite being present, egf-cfc does not play a role in the establishment of LRA in gastropods. However, experiments in zebrafish suggest that a single amino acid mutation in the egf-cfc gene in at least the common ancestor of chordates was the necessary step to induce a gain of function in LRA regulation. This study shows that the egf-cfc gene likely appeared in the ancestors of deuterostomes and "protostomes", before being adopted as a mechanism to regulate the Nodal pathway and the establishment of LRA in some lineages of deuterostomes.
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Affiliation(s)
| | - Kimberly J Perry
- Department of Cell and Developmental Biology, University of Illinois, Urbana, IL 61801
| | - Florencia Cavodeassi
- Departamento de Biología, Facultad de Ciencias, Universidad Autónoma de Madrid, Madrid, Spain,Institute of Medical and Biomedical Education, St George's University of London, Cranmer Terrace, London SW17 0RE, United Kingdom
| | - Nathan J Kenny
- Natural History Museum, Cromwell Road, London, United Kingdom,Department of Biochemistry (Te Tari Matū Koiora), University of Otago, Dunedin, (Aotearoa) New Zealand
| | - Jonathan Q Henry
- Department of Cell and Developmental Biology, University of Illinois, Urbana, IL 61801,The Marine Biological Laboratory, Woods Hole, MA 02543
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4
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Schmidt-Ott U, Yoon Y. Evolution and loss of ß-catenin and TCF-dependent axis specification in insects. CURRENT OPINION IN INSECT SCIENCE 2022; 50:100877. [PMID: 35104659 PMCID: PMC9133022 DOI: 10.1016/j.cois.2022.100877] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/26/2021] [Revised: 01/06/2022] [Accepted: 01/11/2022] [Indexed: 06/14/2023]
Abstract
Mechanisms and evolution of primary axis specification in insects are discussed in the context of the roles of ß-catenin and TCF in polarizing metazoan embryos. Three hypotheses are presented. First, insects with sequential segmentation and posterior growth use cell-autonomous mechanisms for establishing embryo polarity via the nuclear ratio of ß-catenin and TCF. Second, TCF homologs establish competence for anterior specification. Third, the evolution of simultaneous segmentation mechanisms, also known as long-germ development, resulted in primary axis specification mechanisms that are independent of ß-catenin but reliant on TCF, a condition that preceded the frequent replacement of anterior determinants in long germ insects.
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Affiliation(s)
- Urs Schmidt-Ott
- University of Chicago, Dept. of Organismal Biology and Anatomy, 1027 East 57th Street, Chicago, IL 60637, USA.
| | - Yoseop Yoon
- University of California, Irvine, Dept. of Microbiology and Molecular Genetics, School of Medicine, 811 Health Sciences Rd., Med Sci B262, CA 92617, USA
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5
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Seaver EC. Sifting through the mud: A tale of building the annelid Capitella teleta for EvoDevo studies. Curr Top Dev Biol 2022; 147:401-432. [PMID: 35337457 DOI: 10.1016/bs.ctdb.2021.12.018] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Over the last few decades, the annelid Capitella teleta has been used increasingly as a study system for investigations of development and regeneration. Its favorable properties include an ability to continuously maintain a laboratory culture, availability of a sequenced genome, a stereotypic cleavage program of early development, substantial regeneration abilities, and established experimental and functional genomics techniques. With this review I tell of my adventure of establishing the Capitella teleta as an emerging model and share examples of a few of the contributions our work has made to the fields of evo-devo and developmental biology. I highlight examples of conservation in developmental programs as well as surprising deviations from existing paradigms that highlight the importance of leveraging biological diversity to shift thinking in the field. The story for each study system is unique, and every animal has its own advantages and disadvantages as an experimental system. Just like most progress in science, it takes strategy, hard work and determination to develop tools and resources for a less studied animal, but luck and serendipity also play a role. I include a few narratives to personalize the science, share details of the story that are not included in typical publications, and provide perspective for investigators who are interested in developing their own study organism.
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Affiliation(s)
- Elaine C Seaver
- Whitney Laboratory for Marine Bioscience, University of Florida, St. Augustine, FL, United States.
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6
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Tan S, Huan P, Liu B. Molluscan dorsal-ventral patterning relying on BMP2/4 and Chordin provides insights into spiralian development and evolution. Mol Biol Evol 2021; 39:6424002. [PMID: 34751376 PMCID: PMC8789067 DOI: 10.1093/molbev/msab322] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Although a conserved mechanism relying on BMP2/4 and Chordin is suggested for animal dorsal–ventral (DV) patterning, this mechanism has not been reported in spiralians, one of the three major clades of bilaterians. Studies on limited spiralian representatives have suggested markedly diverse DV patterning mechanisms, a considerable number of which no longer deploy BMP signaling. Here, we showed that BMP2/4 and Chordin regulate DV patterning in the mollusk Lottia goshimai, which was predicted in spiralians but not previously reported. In the context of the diverse reports in spiralians, it conversely represents a relatively unusual case. We showed that BMP2/4 and Chordin coordinate to mediate signaling from the D-quadrant organizer to induce the DV axis, and Chordin relays the symmetry-breaking information from the organizer. Further investigations on L. goshimai embryos with impaired DV patterning suggested roles of BMP signaling in regulating the behavior of the blastopore and the organization of the nervous system. These findings provide insights into the evolution of animal DV patterning and the unique development mode of spiralians driven by the D-quadrant organizer.
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Affiliation(s)
- Sujian Tan
- CAS and Shandong Province Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, 266071, China.,Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao, 266000, China.,Center for Ocean Mega-Science, Chinese Academy of Sciences, Qingdao, 266071, China
| | - Pin Huan
- CAS and Shandong Province Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, 266071, China.,Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao, 266000, China.,Center for Ocean Mega-Science, Chinese Academy of Sciences, Qingdao, 266071, China
| | - Baozhong Liu
- CAS and Shandong Province Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, 266071, China.,Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao, 266000, China.,Center for Ocean Mega-Science, Chinese Academy of Sciences, Qingdao, 266071, China
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7
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Webster NB, Corbet M, Sur A, Meyer NP. Role of BMP signaling during early development of the annelid Capitella teleta. Dev Biol 2021; 478:183-204. [PMID: 34216573 DOI: 10.1016/j.ydbio.2021.06.011] [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: 11/07/2020] [Revised: 05/20/2021] [Accepted: 06/22/2021] [Indexed: 11/16/2022]
Abstract
The mechanisms regulating nervous system development are still unknown for a wide variety of taxa. In insects and vertebrates, bone morphogenetic protein (BMP) signaling plays a key role in establishing the dorsal-ventral (D-V) axis and limiting the neuroectoderm to one side of that axis, leading to speculation about the conserved evolution of centralized nervous systems. Studies outside of insects and vertebrates show a more diverse picture of what, if any role, BMP signaling plays in neural development across Bilateria. This is especially true in the morphologically diverse Spiralia (≈Lophotrochozoa). Despite several studies of D-V axis formation and neural induction in spiralians, there is no consensus for how these two processes are related, or whether BMP signaling may have played an ancestral role in either process. To determine the function of BMP signaling during early development of the spiralian annelid Capitella teleta, we incubated embryos and larvae in BMP4 protein for different amounts of time. Adding exogenous BMP protein to early-cleaving C. teleta embryos had a striking effect on formation of the brain, eyes, foregut, and ventral midline in a time-dependent manner. However, adding BMP did not block brain or VNC formation or majorly disrupt the D-V axis. We identified three key time windows of BMP activity. 1) BMP treatment around birth of the 3rd-quartet micromeres caused the loss of the eyes, radialization of the brain, and a reduction of the foregut, which we interpret as a loss of A- and C-quadrant identities with a possible trans-fate switch to a D-quadrant identity. 2) Treatment after the birth of micromere 4d induced formation of a third ectopic brain lobe, eye, and foregut lobe, which we interpret as a trans-fate switch of B-quadrant micromeres to a C-quadrant identity. 3) Continuous BMP treatment from late cleavage (4d + 12 h) through mid-larval stages resulted in a modest expansion of Ct-chrdl expression in the dorsal ectoderm and a concomitant loss of the ventral midline (neurotroch ciliary band). Loss of the ventral midline was accompanied by a collapse of the bilaterally-symmetric ventral nerve cord, although the total amount of neural tissue was not greatly affected. Our results compared with those from other annelids and molluscs suggest that BMP signaling was not ancestrally involved in delimiting neural tissue to one region of the D-V axis. However, the effects of ectopic BMP on quadrant-identity during cleavage stages may represent a non-axial organizing signal that was present in the last common ancestor of annelids and mollusks. Furthermore, in the last common ancestor of annelids, BMP signaling may have functioned in patterning ectodermal fates along the D-V axis in the trunk. Ultimately, studies on a wider range of spiralian taxa are needed to determine the role of BMP signaling during neural induction and neural patterning in the last common ancestor of this group. Ultimately, these comparisons will give us insight into the evolutionary origins of centralized nervous systems and body plans.
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Affiliation(s)
- Nicole B Webster
- Clark University Biology Department, 950 Main Street, Worcester, MA, 01610, USA.
| | - Michele Corbet
- Clark University Biology Department, 950 Main Street, Worcester, MA, 01610, USA
| | - Abhinav Sur
- Clark University Biology Department, 950 Main Street, Worcester, MA, 01610, USA
| | - Néva P Meyer
- Clark University Biology Department, 950 Main Street, Worcester, MA, 01610, USA.
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8
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Pechmann M, Kenny NJ, Pott L, Heger P, Chen YT, Buchta T, Özüak O, Lynch J, Roth S. Striking parallels between dorsoventral patterning in Drosophila and Gryllus reveal a complex evolutionary history behind a model gene regulatory network. eLife 2021; 10:e68287. [PMID: 33783353 PMCID: PMC8051952 DOI: 10.7554/elife.68287] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2021] [Accepted: 03/24/2021] [Indexed: 12/18/2022] Open
Abstract
Dorsoventral pattering relies on Toll and BMP signalling in all insects studied so far, with variations in the relative contributions of both pathways. Drosophila and the beetle Tribolium share extensive dependence on Toll, while representatives of more distantly related lineages like the wasp Nasonia and bug Oncopeltus rely more strongly on BMP signalling. Here, we show that in the cricket Gryllus bimaculatus, an evolutionarily distant outgroup, Toll has, like in Drosophila, a direct patterning role for the ventral half of the embryo. In addition, Toll polarises BMP signalling, although this does not involve the conserved BMP inhibitor Sog/Chordin. Finally, Toll activation relies on ovarian patterning mechanisms with striking similarity to Drosophila. Our data suggest two surprising hypotheses: (1) that Toll's patterning function in Gryllus and Drosophila is the result of convergent evolution or (2) a Drosophila-like system arose early in insect evolution and was extensively altered in multiple independent lineages.
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Affiliation(s)
- Matthias Pechmann
- Institute for Zoology/Developmental Biology, Biocenter, University of CologneKölnGermany
| | | | - Laura Pott
- Institute for Zoology/Developmental Biology, Biocenter, University of CologneKölnGermany
| | - Peter Heger
- Regional Computing Centre (RRZK), University of CologneKölnGermany
| | - Yen-Ta Chen
- Institute for Zoology/Developmental Biology, Biocenter, University of CologneKölnGermany
| | - Thomas Buchta
- Institute for Zoology/Developmental Biology, Biocenter, University of CologneKölnGermany
| | - Orhan Özüak
- Institute for Zoology/Developmental Biology, Biocenter, University of CologneKölnGermany
| | - Jeremy Lynch
- Institute for Zoology/Developmental Biology, Biocenter, University of CologneKölnGermany
- Department of Biological Sciences, University of Illinois at ChicagoChicagoUnited States
| | - Siegfried Roth
- Institute for Zoology/Developmental Biology, Biocenter, University of CologneKölnGermany
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9
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Cloutier JK, McMann CL, Oderberg IM, Reddien PW. activin-2 is required for regeneration of polarity on the planarian anterior-posterior axis. PLoS Genet 2021; 17:e1009466. [PMID: 33780442 PMCID: PMC8057570 DOI: 10.1371/journal.pgen.1009466] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2020] [Revised: 04/20/2021] [Accepted: 03/03/2021] [Indexed: 01/16/2023] Open
Abstract
Planarians are flatworms and can perform whole-body regeneration. This ability involves a mechanism to distinguish between anterior-facing wounds that require head regeneration and posterior-facing wounds that require tail regeneration. How this head-tail regeneration polarity decision is made is studied to identify principles underlying tissue-identity specification in regeneration. We report that inhibition of activin-2, which encodes an Activin-like signaling ligand, resulted in the regeneration of ectopic posterior-facing heads following amputation. During tissue turnover in uninjured planarians, positional information is constitutively expressed in muscle to maintain proper patterning. Positional information includes Wnts expressed in the posterior and Wnt antagonists expressed in the anterior. Upon amputation, several wound-induced genes promote re-establishment of positional information. The head-versus-tail regeneration decision involves preferential wound induction of the Wnt antagonist notum at anterior-facing over posterior-facing wounds. Asymmetric activation of notum represents the earliest known molecular distinction between head and tail regeneration, yet how it occurs is unknown. activin-2 RNAi animals displayed symmetric wound-induced activation of notum at anterior- and posterior-facing wounds, providing a molecular explanation for their ectopic posterior-head phenotype. activin-2 RNAi animals also displayed anterior-posterior (AP) axis splitting, with two heads appearing in anterior blastemas, and various combinations of heads and tails appearing in posterior blastemas. This was associated with ectopic nucleation of anterior poles, which are head-tip muscle cells that facilitate AP and medial-lateral (ML) pattern at posterior-facing wounds. These findings reveal a role for Activin signaling in determining the outcome of AP-axis-patterning events that are specific to regeneration. A central problem in animal regeneration is how animals determine what body part to regenerate. Planarians are flatworms that can regenerate any missing body region, and are studied to identify mechanisms underlying regeneration. At transverse amputation planes, a poorly understood mechanism specifies regeneration of either a head or a tail. This head-versus-tail regeneration decision-making process is referred to as regeneration polarity and has been studied for over a century to identify mechanisms that specify what to regenerate. The gene notum, which encodes a Wnt antagonist, is induced within hours after injury preferentially at anterior-facing wounds, where it specifies head regeneration. We report that Activin signaling is required for regeneration polarity, and the underlying asymmetric activation of notum at anterior- over posterior-facing wounds. We propose that Activin signaling is involved in regeneration-specific responses broadly in the animal kingdom.
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Affiliation(s)
- Jennifer K. Cloutier
- Whitehead Institute for Biomedical Research, Cambridge, MA, United States of America
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA, United States of America
- Howard Hughes Medical Institute, Chevy Chase, MD, United States of America
- Harvard/MIT MD-PhD, Harvard Medical School, Boston, MA, United States of America
| | - Conor L. McMann
- Whitehead Institute for Biomedical Research, Cambridge, MA, United States of America
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA, United States of America
- Howard Hughes Medical Institute, Chevy Chase, MD, United States of America
| | - Isaac M. Oderberg
- Whitehead Institute for Biomedical Research, Cambridge, MA, United States of America
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA, United States of America
- Howard Hughes Medical Institute, Chevy Chase, MD, United States of America
| | - Peter W. Reddien
- Whitehead Institute for Biomedical Research, Cambridge, MA, United States of America
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA, United States of America
- Howard Hughes Medical Institute, Chevy Chase, MD, United States of America
- * E-mail:
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10
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Lanza AR, Seaver EC. Functional evidence that Activin/Nodal signaling is required for establishing the dorsal-ventral axis in the annelid Capitella teleta. Development 2020; 147:147/18/dev189373. [PMID: 32967906 PMCID: PMC7522025 DOI: 10.1242/dev.189373] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2020] [Accepted: 08/06/2020] [Indexed: 12/25/2022]
Abstract
The TGF-β superfamily comprises two distinct branches: the Activin/Nodal and BMP pathways. During development, signaling by this superfamily regulates a variety of embryological processes, and it has a conserved role in patterning the dorsal-ventral body axis. Recent studies show that BMP signaling establishes the dorsal-ventral axis in some mollusks. However, previous pharmacological inhibition studies in the annelid Capitella teleta, a sister clade to the mollusks, suggests that the dorsal-ventral axis is patterned via Activin/Nodal signaling. Here, we determine the role of both the Activin/Nodal and BMP pathways as they function in Capitella axis patterning. Antisense morpholino oligonucleotides were targeted to Ct-Smad2/3 and Ct-Smad1/5/8, transcription factors specific to the Activin/Nodal and BMP pathways, respectively. Following microinjection of zygotes, resulting morphant larvae were scored for axial anomalies. We demonstrate that the Activin/Nodal pathway of the TGF-β superfamily, but not the BMP pathway, is the primary dorsal-ventral patterning signal in Capitella. These results demonstrate variation in the molecular control of axis patterning across spiralians, despite sharing a conserved cleavage program. We suggest that these findings represent an example of developmental system drift. Summary: Morpholino knockdown experiments in the annelid Capitella teleta demonstrate that the dorsal-ventral axis is primarily patterned by the Activin/Nodal pathway of the TGF-β superfamily, rather than by the BMP pathway.
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Affiliation(s)
- Alexis R Lanza
- Whitney Laboratory for Marine Bioscience, University of Florida, 9505 Ocean Shore Boulevard, St Augustine, FL 32080-8610, USA
| | - Elaine C Seaver
- Whitney Laboratory for Marine Bioscience, University of Florida, 9505 Ocean Shore Boulevard, St Augustine, FL 32080-8610, USA
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11
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Heger P, Zheng W, Rottmann A, Panfilio KA, Wiehe T. The genetic factors of bilaterian evolution. eLife 2020; 9:e45530. [PMID: 32672535 PMCID: PMC7535936 DOI: 10.7554/elife.45530] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2019] [Accepted: 07/03/2020] [Indexed: 12/13/2022] Open
Abstract
The Cambrian explosion was a unique animal radiation ~540 million years ago that produced the full range of body plans across bilaterians. The genetic mechanisms underlying these events are unknown, leaving a fundamental question in evolutionary biology unanswered. Using large-scale comparative genomics and advanced orthology evaluation techniques, we identified 157 bilaterian-specific genes. They include the entire Nodal pathway, a key regulator of mesoderm development and left-right axis specification; components for nervous system development, including a suite of G-protein-coupled receptors that control physiology and behaviour, the Robo-Slit midline repulsion system, and the neurotrophin signalling system; a high number of zinc finger transcription factors; and novel factors that previously escaped attention. Contradicting the current view, our study reveals that genes with bilaterian origin are robustly associated with key features in extant bilaterians, suggesting a causal relationship.
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Affiliation(s)
- Peter Heger
- Institute for Genetics, Cologne Biocenter, University of CologneCologneGermany
| | - Wen Zheng
- Institute for Genetics, Cologne Biocenter, University of CologneCologneGermany
| | - Anna Rottmann
- Institute for Genetics, Cologne Biocenter, University of CologneCologneGermany
| | - Kristen A Panfilio
- Institute for Zoology: Developmental Biology, Cologne Biocenter, University of CologneCologneGermany
- School of Life Sciences, University of Warwick, Gibbet Hill CampusCoventryUnited Kingdom
| | - Thomas Wiehe
- Institute for Genetics, Cologne Biocenter, University of CologneCologneGermany
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12
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Lyons DC, Perry KJ, Batzel G, Henry JQ. BMP signaling plays a role in anterior-neural/head development, but not organizer activity, in the gastropod Crepidula fornicata. Dev Biol 2020; 463:135-157. [PMID: 32389712 PMCID: PMC7444637 DOI: 10.1016/j.ydbio.2020.04.008] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2019] [Revised: 04/21/2020] [Accepted: 04/23/2020] [Indexed: 02/06/2023]
Abstract
BMP signaling is involved in many aspects of metazoan development, with two of the most conserved functions being to pattern the dorsal-ventral axis and to specify neural versus epidermal fates. An active area of research within developmental biology asks how BMP signaling was modified over evolution to build disparate body plans. Animals belonging to the superclade Spiralia/Lophotrochozoa are excellent experimental subjects for studying the evolution of BMP signaling because a highly conserved, stereotyped early cleavage program precedes the emergence of distinct body plans. In this study we examine the role of BMP signaling in one representative, the slipper snail Crepidula fornicata. We find that mRNAs encoding BMP pathway components (including the BMP ligand decapentaplegic, and BMP antagonists chordin and noggin-like proteins) are not asymmetrically localized along the dorsal-ventral axis in the early embryo, as they are in other species. Furthermore, when BMP signaling is perturbed by adding ectopic recombinant BMP4 protein, or by treating embryos with the selective Activin receptor-like kinase-2 (ALK-2) inhibitor Dorsomorphin Homolog 1 (DMH1), we observe no obvious effects on dorsal-ventral patterning within the posterior (post-trochal) region of the embryo. Instead, we see effects on head development and the balance between neural and epidermal fates specifically within the anterior, pre-trochal tissue derived from the 1q1 lineage. Our experiments define a window of BMP signaling sensitivity that ends at approximately 44-48 hours post fertilization, which occurs well after organizer activity has ended and after the dorsal-ventral axis has been determined. When embryos were exposed to BMP4 protein during this window, we observed morphogenetic defects leading to the separation of the anterior, 1q lineage from the rest of the embryo. The 1q-derived organoid remained largely undifferentiated and was radialized, while the post-trochal portion of the embryo developed relatively normally and exhibited clear signs of dorsal-ventral patterning. When embryos were exposed to DMH1 during the same time interval, we observed defects in the head, including protrusion of the apical plate, enlarged cerebral ganglia and ectopic ocelli, but otherwise the larvae appeared normal. No defects in shell development were noted following DMH1 treatments. The varied roles of BMP signaling in the development of several other spiralians have recently been examined. We discuss our results in this context, and highlight the diversity of developmental mechanisms within spiral-cleaving animals.
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Affiliation(s)
- Deirdre C Lyons
- Scripps Institution of Oceanography, U.C. San Diego, 9500 Gilman Drive, La Jolla, CA, 92093, USA.
| | - Kimberly J Perry
- University of Illinois, Department of Cell & Developmental Biology, 601 S. Goodwin Ave., Urbana, IL, 61801, USA
| | - Grant Batzel
- Scripps Institution of Oceanography, U.C. San Diego, 9500 Gilman Drive, La Jolla, CA, 92093, USA
| | - Jonathan Q Henry
- University of Illinois, Department of Cell & Developmental Biology, 601 S. Goodwin Ave., Urbana, IL, 61801, USA.
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Zhang H, Chen S, Shang C, Wu X, Wang Y, Li G. Interplay between Lefty and Nodal signaling is essential for the organizer and axial formation in amphioxus embryos. Dev Biol 2019; 456:63-73. [DOI: 10.1016/j.ydbio.2019.08.006] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2019] [Revised: 08/12/2019] [Accepted: 08/12/2019] [Indexed: 01/04/2023]
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14
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Álvarez-Campos P, Kenny NJ, Verdes A, Fernández R, Novo M, Giribet G, Riesgo A. Delegating Sex: Differential Gene Expression in Stolonizing Syllids Uncovers the Hormonal Control of Reproduction. Genome Biol Evol 2019; 11:295-318. [PMID: 30535381 PMCID: PMC6350857 DOI: 10.1093/gbe/evy265] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/09/2018] [Indexed: 12/31/2022] Open
Abstract
Stolonization in syllid annelids is a unique mode of reproduction among animals. During the breeding season, a structure resembling the adult but containing only gametes, called stolon, is formed generally at the posterior end of the animal. When stolons mature, they detach from the adult and gametes are released into the water column. The process is synchronized within each species, and it has been reported to be under environmental and endogenous control, probably via endocrine regulation. To further understand reproduction in syllids and to elucidate the molecular toolkit underlying stolonization, we generated Illumina RNA-seq data from different tissues of reproductive and nonreproductive individuals of Syllis magdalena and characterized gene expression during the stolonization process. Several genes involved in gametogenesis (ovochymase, vitellogenin, testis-specific serine/threonine-kinase), immune response (complement receptor 2), neuronal development (tyrosine-protein kinase Src42A), cell proliferation (alpha-1D adrenergic receptor), and steroid metabolism (hydroxysteroid dehydrogenase 2) were found differentially expressed in the different tissues and conditions analyzed. In addition, our findings suggest that several neurohormones, such as methyl farnesoate, dopamine, and serotonin, might trigger stolon formation, the correct maturation of gametes and the detachment of stolons when gametogenesis ends. The process seems to be under circadian control, as indicated by the expression patterns of r-opsins. Overall, our results shed light into the genes that orchestrate the onset of gamete formation and improve our understanding of how some hormones, previously reported to be involved in reproduction and metamorphosis processes in other invertebrates, seem to also regulate reproduction via stolonization.
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Affiliation(s)
- Patricia Álvarez-Campos
- Facultad de Ciencias, Departamento de Biología (Zoología), Universidad Autónoma de Madrid, Spain
- Museum of Comparative Zoology, Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, Massachusetts
- Department of Life Sciences, The Natural History Museum of London, London, United Kingdom
- Department of Biological & Medical Sciences, Oxford Brookes University, Headington Campus, Gipsy Lane, Oxford, United Kingdom
| | - Nathan J Kenny
- Department of Life Sciences, The Natural History Museum of London, London, United Kingdom
| | - Aida Verdes
- Facultad de Ciencias, Departamento de Biología (Zoología), Universidad Autónoma de Madrid, Spain
- Department of Biology, The Graduate Center, City University of New York
- Sackler Institute for Comparative Genomics, American Museum of Natural History, New York, New York
| | - Rosa Fernández
- Bioinformatics & Genomics Unit, Center for Genomic Regulation, Barcelona, Spain
| | - Marta Novo
- Facultad de Biología, Departamento de Biodiversidad, Ecología y Evolución, Universidad Complutense de Madrid, Spain
| | - Gonzalo Giribet
- Museum of Comparative Zoology, Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, Massachusetts
| | - Ana Riesgo
- Department of Biology, The Graduate Center, City University of New York
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Olson PD, Zarowiecki M, James K, Baillie A, Bartl G, Burchell P, Chellappoo A, Jarero F, Tan LY, Holroyd N, Berriman M. Genome-wide transcriptome profiling and spatial expression analyses identify signals and switches of development in tapeworms. EvoDevo 2018; 9:21. [PMID: 30455861 PMCID: PMC6225667 DOI: 10.1186/s13227-018-0110-5] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2018] [Accepted: 10/05/2018] [Indexed: 02/06/2023] Open
Abstract
BACKGROUND Tapeworms are agents of neglected tropical diseases responsible for significant health problems and economic loss. They also exhibit adaptations to a parasitic lifestyle that confound comparisons of their development with other animals. Identifying the genetic factors regulating their complex ontogeny is essential to understanding unique aspects of their biology and for advancing novel therapeutics. Here we use RNA sequencing to identify up-regulated signalling components, transcription factors and post-transcriptional/translational regulators (genes of interest, GOI) in the transcriptomes of Larvae and different regions of segmented worms in the tapeworm Hymenolepis microstoma and combine this with spatial gene expression analyses of a selection of genes. RESULTS RNA-seq reads collectively mapped to 90% of the > 12,000 gene models in the H. microstoma v.2 genome assembly, demonstrating that the transcriptome profiles captured a high percentage of predicted genes. Contrasts made between the transcriptomes of Larvae and whole, adult worms, and between the Scolex-Neck, mature strobila and gravid strobila, resulted in 4.5-30% of the genes determined to be differentially expressed. Among these, we identified 190 unique GOI up-regulated in one or more contrasts, including a large range of zinc finger, homeobox and other transcription factors, components of Wnt, Notch, Hedgehog and TGF-β/BMP signalling, and post-transcriptional regulators (e.g. Boule, Pumilio). Heatmap clusterings based on overall expression and on select groups of genes representing 'signals' and 'switches' showed that expression in the Scolex-Neck region is more similar to that of Larvae than to the mature or gravid regions of the adult worm, which was further reflected in large overlap of up-regulated GOI. CONCLUSIONS Spatial expression analyses in Larvae and adult worms corroborated inferences made from quantitative RNA-seq data and in most cases indicated consistency with canonical roles of the genes in other animals, including free-living flatworms. Recapitulation of developmental factors up-regulated during larval metamorphosis suggests that strobilar growth involves many of the same underlying gene regulatory networks despite the significant disparity in developmental outcomes. The majority of genes identified were investigated in tapeworms for the first time, setting the stage for advancing our understanding of developmental genetics in an important group of flatworm parasites.
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Affiliation(s)
- Peter D. Olson
- Division of Parasites and Vectors, Department of Life Sciences, The Natural History Museum, Cromwell Road, London, SW7 5BD UK
| | - Magdalena Zarowiecki
- Division of Parasites and Vectors, Department of Life Sciences, The Natural History Museum, Cromwell Road, London, SW7 5BD UK
- Parasite Genomics, Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge, CB10 1SA UK
| | - Katherine James
- Division of Parasites and Vectors, Department of Life Sciences, The Natural History Museum, Cromwell Road, London, SW7 5BD UK
| | - Andrew Baillie
- Division of Parasites and Vectors, Department of Life Sciences, The Natural History Museum, Cromwell Road, London, SW7 5BD UK
| | - Georgie Bartl
- Division of Parasites and Vectors, Department of Life Sciences, The Natural History Museum, Cromwell Road, London, SW7 5BD UK
| | - Phil Burchell
- Division of Parasites and Vectors, Department of Life Sciences, The Natural History Museum, Cromwell Road, London, SW7 5BD UK
| | - Azita Chellappoo
- Division of Parasites and Vectors, Department of Life Sciences, The Natural History Museum, Cromwell Road, London, SW7 5BD UK
| | - Francesca Jarero
- Division of Parasites and Vectors, Department of Life Sciences, The Natural History Museum, Cromwell Road, London, SW7 5BD UK
| | - Li Ying Tan
- Division of Parasites and Vectors, Department of Life Sciences, The Natural History Museum, Cromwell Road, London, SW7 5BD UK
| | - Nancy Holroyd
- Parasite Genomics, Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge, CB10 1SA UK
| | - Matt Berriman
- Parasite Genomics, Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge, CB10 1SA UK
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Abstract
Lophotrochozoa is a sister taxon of Ecdysozoa in the Protostomia that includes mollusks, annelids, brachiopods, and platyhelminths. Recent studies have clarified the structure, expression, and roles of lophotrochozoan Zic family genes. Zic genes in oligochaete annelid Tubifex tubifex (freshwater sludge worm) and polychaete annelid Capitella teleta (bristle worm) are commonly expressed in a subset of developing brain and mesoderm derivatives. The latter includes the naïve mesoderm and the associated chaetal sacs in each body segment, although the segmentation processes differ between the two species. Furthermore, in brachiopod Terebratalia transversa (lamp shell), Zic is expressed in the anterior ectodermal domains and mesodermal derivatives, including those associated with the chaetal sacs. This result suggests the common involvement of Zic genes in the development of chaetae, a lophotrochozoan novelty acquired in the course of evolution. In addition, the highly simplified lophotrochozoan Dicyema acuticephalum (dicyemid mesozoan, a cephalopod endoparasite), which lost its gut, nervous system, and muscles during evolution, expresses its Zic genes in hermaphroditic gonads, highlighting the role of Zic genes in germ cell development. The role of Zic in head regeneration was revealed in studies on platyhelminth Schmidtea mediterranea (freshwater planarian). Planarian Zic expression was induced in a subpopulation of neoblasts that includes adult pluripotent stem cells. It is needed for head regeneration and production of an anterior signaling center. Suppression of Wnt-β-catenin signaling underlies Zic-mediated head regeneration, reminiscent of Wnt-β-catenin suppression by vertebrate Zic genes. Taken together, studies on the lophotrochozoan Zic genes are essential to understanding not only the roles of these genes in body plan evolution but also the molecular mechanism underlying adult stem cell regulation.
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17
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Tan S, Huan P, Liu B. An investigation of oyster TGF-β receptor genes and their potential roles in early molluscan development. Gene 2018; 663:65-71. [DOI: 10.1016/j.gene.2018.04.035] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2018] [Revised: 03/19/2018] [Accepted: 04/12/2018] [Indexed: 10/17/2022]
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18
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Lanza AR, Seaver EC. An organizing role for the TGF-β signaling pathway in axes formation of the annelid Capitella teleta. Dev Biol 2018; 435:26-40. [DOI: 10.1016/j.ydbio.2018.01.004] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2017] [Revised: 01/09/2018] [Accepted: 01/09/2018] [Indexed: 01/12/2023]
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Cerberus-Nodal-Lefty-Pitx signaling cascade controls left -right asymmetry in amphioxus. Proc Natl Acad Sci U S A 2017; 114:3684-3689. [PMID: 28320954 DOI: 10.1073/pnas.1620519114] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Many bilaterally symmetrical animals develop genetically programmed left-right asymmetries. In vertebrates, this process is under the control of Nodal signaling, which is restricted to the left side by Nodal antagonists Cerberus and Lefty. Amphioxus, the earliest diverging chordate lineage, has profound left-right asymmetry as a larva. We show that Cerberus, Nodal, Lefty, and their target transcription factor Pitx are sequentially activated in amphioxus embryos. We then address their function by transcription activator-like effector nucleases (TALEN)-based knockout and heat-shock promoter (HSP)-driven overexpression. Knockout of Cerberus leads to ectopic right-sided expression of Nodal, Lefty, and Pitx, whereas overexpression of Cerberus represses their left-sided expression. Overexpression of Nodal in turn represses Cerberus and activates Lefty and Pitx ectopically on the right side. We also show Lefty represses Nodal, whereas Pitx activates Nodal These data combine in a model in which Cerberus determines whether the left-sided gene expression cassette is activated or repressed. These regulatory steps are essential for normal left-right asymmetry to develop, as when they are disrupted embryos may instead form two phenotypic left sides or two phenotypic right sides. Our study shows the regulatory cassette controlling left-right asymmetry was in place in the ancestor of amphioxus and vertebrates. This includes the Nodal inhibitors Cerberus and Lefty, both of which operate in feedback loops with Nodal and combine to establish asymmetric Pitx expression. Cerberus and Lefty are missing from most invertebrate lineages, marking this mechanism as an innovation in the lineage leading to modern chordates.
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20
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Benton MA, Kenny NJ, Conrads KH, Roth S, Lynch JA. Deep, Staged Transcriptomic Resources for the Novel Coleopteran Models Atrachya menetriesi and Callosobruchus maculatus. PLoS One 2016; 11:e0167431. [PMID: 27907180 PMCID: PMC5132259 DOI: 10.1371/journal.pone.0167431] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2016] [Accepted: 11/14/2016] [Indexed: 11/18/2022] Open
Abstract
Despite recent efforts to sample broadly across metazoan and insect diversity, current sequence resources in the Coleoptera do not adequately describe the diversity of the clade. Here we present deep, staged transcriptomic data for two coleopteran species, Atrachya menetriesi (Faldermann 1835) and Callosobruchus maculatus (Fabricius 1775). Our sampling covered key stages in ovary and early embryonic development in each species. We utilized this data to build combined assemblies for each species which were then analysed in detail. The combined A. menetriesi assembly consists of 228,096 contigs with an N50 of 1,598 bp, while the combined C. maculatus assembly consists of 128,837 contigs with an N50 of 2,263 bp. For these assemblies, 34.6% and 32.4% of contigs were identified using Blast2GO, and 97% and 98.3% of the BUSCO set of metazoan orthologs were present, respectively. We also carried out manual annotation of developmental signalling pathways and found that nearly all expected genes were present in each transcriptome. Our analyses show that both transcriptomes are of high quality. Lastly, we performed read mapping utilising our timed, stage specific RNA samples to identify differentially expressed contigs. The resources presented here will provide a firm basis for a variety of experimentation, both in developmental biology and in comparative genomic studies.
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Affiliation(s)
- Matthew A. Benton
- Institute for Developmental Biology, University of Cologne, Cologne, Germany
| | - Nathan J. Kenny
- Simon F.S. Li School of Life Sciences, The Chinese University of Hong Kong, Shatin, Hong Kong
| | - Kai H. Conrads
- Institute for Developmental Biology, University of Cologne, Cologne, Germany
| | - Siegfried Roth
- Institute for Developmental Biology, University of Cologne, Cologne, Germany
- * E-mail: (SR); (JAL)
| | - Jeremy A. Lynch
- Department of Biological Sciences, University of Illinois at Chicago, Chicago, Illinois, United States of America
- * E-mail: (SR); (JAL)
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21
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Seaver EC. Annelid models I: Capitella teleta. Curr Opin Genet Dev 2016; 39:35-41. [DOI: 10.1016/j.gde.2016.05.025] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2016] [Revised: 05/26/2016] [Accepted: 05/30/2016] [Indexed: 10/21/2022]
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Lapraz F, Haillot E, Lepage T. A deuterostome origin of the Spemann organiser suggested by Nodal and ADMPs functions in Echinoderms. Nat Commun 2015; 6:8434. [PMID: 26423516 PMCID: PMC4600745 DOI: 10.1038/ncomms9434] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2015] [Accepted: 08/20/2015] [Indexed: 01/05/2023] Open
Abstract
During development of chordates, establishment of the body plan relies on the activity of an organizing centre located on the dorsal side of the embryo that patterns the embryo and induces neural tissue. Intriguingly, the evolutionary origin of this crucial signalling centre remains unclear and whether analogous organizers regulate D/V patterning in other deuterostome or protostome phyla is not known. Here we provide evidence that the ventral ectoderm of the sea urchin embryo is a long-range organizing centre that shares several fundamental properties with the Spemann organizer: the ability to induce duplicated embryonic axes when ectopically induced, the ability to induce neural fate in neighbouring tissues and the ability to finely regulate the level of BMP signalling by using an autoregulatory expansion–repression mechanism. These findings suggest that the evolutionary origin of the Spemann organizer is more ancient than previously thought and that it may possibly be traced back to the common ancestor of deuterostomes. Establishment of the body plan in chordates is determined by an organizing centre located on the dorsal side of the embryo. Here, the authors show that the ventral ectoderm of the sea urchin embryo is an organizing centre that shares several fundamental properties with the amphibian Spemann organizer.
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Affiliation(s)
- François Lapraz
- Institut de Biologie Valrose, iBV, UMR 7277 CNRS, Inserm U1091, UNS, University of Nice Sophia Antipolis Nice 06108, 2 France
| | - Emmanuel Haillot
- Institut de Biologie Valrose, iBV, UMR 7277 CNRS, Inserm U1091, UNS, University of Nice Sophia Antipolis Nice 06108, 2 France
| | - Thierry Lepage
- Institut de Biologie Valrose, iBV, UMR 7277 CNRS, Inserm U1091, UNS, University of Nice Sophia Antipolis Nice 06108, 2 France
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