1
|
Dutta S, Hering L, Grollmann MM, Metzendorf N, Gross V, Arakawa K, Neupert S, Stengl M, Herberg FW, Mayer G. Pigment-dispersing factor neuropeptides act as multifunctional hormones and modulators in tardigrades. Open Biol 2025; 15:240242. [PMID: 40037531 PMCID: PMC11879619 DOI: 10.1098/rsob.240242] [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: 08/28/2024] [Revised: 01/15/2025] [Accepted: 02/03/2025] [Indexed: 03/06/2025] Open
Abstract
Pigment-dispersing factors (PDFs) are neuropeptides that play key roles in controlling the circadian rhythms in various insects, whereas their function remains elusive in other protostomes including tardigrades (water bears). Here we show that the three PDFs of the tardigrade Hypsibius exemplaris are co-localized in two pairs of inner lobe cells in the brain, whereas only one PDF occurs in four additional cerebral and two extracerebral cells. The axons of the inner lobe cells pass through the contralateral brain hemisphere, descend to the ventral nerve cord and terminate in two pairs of potential release sites in the posteriormost trunk ganglion. Using in vitro assays, we demonstrate that all three PDFs and their deorphanized receptor (PDFR) are functional. Widespread localization of PDFR suggests that tardigrade PDFs may act as multifunctional hormones and neuromodulators that control major functions including light detection, neural processing, locomotion, feeding, digestion, osmoregulation, growth, embryonic development and oogenesis/reproduction.
Collapse
Affiliation(s)
- Soumi Dutta
- Department of Zoology, University of Kassel, Kassel, Germany
- Graduate School "Multiscale Clocks", University of Kassel, Kassel, Germany
| | - Lars Hering
- Department of Zoology, University of Kassel, Kassel, Germany
| | | | | | - Vladimir Gross
- Central Coordination Office, BMBF Research Initiative for the Conservation of Biodiversity (FEdA), Senckenberg – Leibniz Institution for Biodiversity and Earth System Research, Frankfurt am Main, Germany
| | - Kazuharu Arakawa
- Institute for Advanced Biosciences, Keio University, Tsuruoka, Yamagata, Japan
| | - Susanne Neupert
- Graduate School "Multiscale Clocks", University of Kassel, Kassel, Germany
- Department of Animal Physiology/Neuroethology, University of Kassel, Kassel, Germany
| | - Monika Stengl
- Graduate School "Multiscale Clocks", University of Kassel, Kassel, Germany
- Department of Animal Physiology/Neuroethology, University of Kassel, Kassel, Germany
| | - Friedrich W. Herberg
- Graduate School "Multiscale Clocks", University of Kassel, Kassel, Germany
- Department of Biochemistry, University of Kassel, Kassel, Germany
| | - Georg Mayer
- Department of Zoology, University of Kassel, Kassel, Germany
- Graduate School "Multiscale Clocks", University of Kassel, Kassel, Germany
| |
Collapse
|
2
|
Ordoñez JF, Wollesen T. Unfolding the ventral nerve center of chaetognaths. Neural Dev 2024; 19:5. [PMID: 38720353 PMCID: PMC11078758 DOI: 10.1186/s13064-024-00182-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2023] [Accepted: 04/17/2024] [Indexed: 05/12/2024] Open
Abstract
BACKGROUND Chaetognaths are a clade of marine worm-like invertebrates with a heavily debated phylogenetic position. Their nervous system superficially resembles the protostome type, however, knowledge regarding the molecular processes involved in neurogenesis is lacking. To better understand these processes, we examined the expression profiles of marker genes involved in bilaterian neurogenesis during post-embryonic stages of Spadella cephaloptera. We also investigated whether the transcription factor encoding genes involved in neural patterning are regionally expressed in a staggered fashion along the mediolateral axis of the nerve cord as it has been previously demonstrated in selected vertebrate, insect, and annelid models. METHODS The expression patterns of genes involved in neural differentiation (elav), neural patterning (foxA, nkx2.2, pax6, pax3/7, and msx), and neuronal function (ChAT and VAChT) were examined in S. cephaloptera hatchlings and early juveniles using whole-mount fluorescent in situ hybridization and confocal microscopy. RESULTS The Sce-elav + profile of S. cephaloptera hatchlings reveals that, within 24 h of post-embryonic development, the developing neural territories are not limited to the regions previously ascribed to the cerebral ganglion, the ventral nerve center (VNC), and the sensory organs, but also extend to previously unreported CNS domains that likely contribute to the ventral cephalic ganglia. In general, the neural patterning genes are expressed in distinct neural subpopulations of the cerebral ganglion and the VNC in hatchlings, eventually becoming broadly expressed with reduced intensity throughout the CNS in early juveniles. Neural patterning gene expression domains are also present outside the CNS, including the digestive tract and sensory organs. ChAT and VAChT domains within the CNS are predominantly observed in specific subpopulations of the VNC territory adjacent to the ventral longitudinal muscles in hatchlings. CONCLUSIONS The observed spatial expression domains of bilaterian neural marker gene homologs in S. cephaloptera suggest evolutionarily conserved roles in neurogenesis for these genes among bilaterians. Patterning genes expressed in distinct regions of the VNC do not show a staggered medial-to-lateral expression profile directly superimposable to other bilaterian models. Only when the VNC is conceptually laterally unfolded from the longitudinal muscle into a flat structure, an expression pattern bearing resemblance to the proposed conserved bilaterian mediolateral regionalization becomes noticeable. This finding supports the idea of an ancestral mediolateral patterning of the trunk nervous system in bilaterians.
Collapse
Affiliation(s)
- June F Ordoñez
- Unit for Integrative Zoology, Department of Evolutionary Biology, University of Vienna, 1030, Vienna, Austria
| | - Tim Wollesen
- Unit for Integrative Zoology, Department of Evolutionary Biology, University of Vienna, 1030, Vienna, Austria.
| |
Collapse
|
3
|
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.
Collapse
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
| |
Collapse
|
4
|
Aase-Remedios ME, Janssen R, Leite DJ, Sumner-Rooney L, McGregor AP. Evolution of the Spider Homeobox Gene Repertoire by Tandem and Whole Genome Duplication. Mol Biol Evol 2023; 40:msad239. [PMID: 37935059 PMCID: PMC10726417 DOI: 10.1093/molbev/msad239] [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: 05/26/2023] [Revised: 10/02/2023] [Accepted: 10/26/2023] [Indexed: 11/09/2023] Open
Abstract
Gene duplication generates new genetic material that can contribute to the evolution of gene regulatory networks and phenotypes. Duplicated genes can undergo subfunctionalization to partition ancestral functions and/or neofunctionalization to assume a new function. We previously found there had been a whole genome duplication (WGD) in an ancestor of arachnopulmonates, the lineage including spiders and scorpions but excluding other arachnids like mites, ticks, and harvestmen. This WGD was evidenced by many duplicated homeobox genes, including two Hox clusters, in spiders. However, it was unclear which homeobox paralogues originated by WGD versus smaller-scale events such as tandem duplications. Understanding this is a key to determining the contribution of the WGD to arachnopulmonate genome evolution. Here we characterized the distribution of duplicated homeobox genes across eight chromosome-level spider genomes. We found that most duplicated homeobox genes in spiders are consistent with an origin by WGD. We also found two copies of conserved homeobox gene clusters, including the Hox, NK, HRO, Irx, and SINE clusters, in all eight species. Consistently, we observed one copy of each cluster was degenerated in terms of gene content and organization while the other remained more intact. Focussing on the NK cluster, we found evidence for regulatory subfunctionalization between the duplicated NK genes in the spider Parasteatoda tepidariorum compared to their single-copy orthologues in the harvestman Phalangium opilio. Our study provides new insights into the relative contributions of multiple modes of duplication to the homeobox gene repertoire during the evolution of spiders and the function of NK genes.
Collapse
Affiliation(s)
| | - Ralf Janssen
- Department of Earth Sciences, Uppsala University, Uppsala, 752 36, Sweden
| | - Daniel J Leite
- Department of Biosciences, Durham University, Durham, DH1 3LE, United Kingdom
| | - Lauren Sumner-Rooney
- Museum für Naturkunde, Leibniz-Institut für Evolutions- und Biodiversitätsforschung, Berlin, 10115, Germany
| | - Alistair P McGregor
- Department of Biosciences, Durham University, Durham, DH1 3LE, United Kingdom
| |
Collapse
|
5
|
Strausfeld NJ, Hou X, Sayre ME, Hirth F. Response to Comment on "The lower Cambrian lobopodian Cardiodictyon resolves the origin of euarthropod brains". Science 2023; 380:eadg6051. [PMID: 37384690 DOI: 10.1126/science.adg6051] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2023] [Accepted: 04/26/2023] [Indexed: 07/01/2023]
Abstract
Budd et al. challenge the identity of neural traces reported for the Cambrian lobopodian Cardiodictyon catenulum. Their argumentation is unsupported, as are objections with reference to living Onychophora that misinterpret established genomic, genetic, developmental, and neuroanatomical evidence. Instead, phylogenetic data corroborate the finding that the ancestral panarthropod head and brain is unsegmented, as in C. catenulum.
Collapse
Affiliation(s)
| | - Xianguang Hou
- Yunnan Key Laboratory for Palaeobiology, Institute of Palaeontology, Yunnan University, Kunming, China
| | - Marcel E Sayre
- Lund University, Lund Vision Group, Department of Biology, Lund, Sweden & Macquarie University, Department of Biological Sciences, Sydney, Australia
| | - Frank Hirth
- Department of Basic and Clinical Neuroscience, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London SE5 9RT, UK
| |
Collapse
|
6
|
He S, Shao W, Chen SC, Wang T, Gibson MC. Spatial transcriptomics reveals a cnidarian segment polarity program in Nematostella vectensis. Curr Biol 2023:S0960-9822(23)00676-0. [PMID: 37315559 DOI: 10.1016/j.cub.2023.05.044] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2022] [Revised: 04/16/2023] [Accepted: 05/18/2023] [Indexed: 06/16/2023]
Abstract
During early animal evolution, the emergence of axially polarized segments was central to the diversification of complex bilaterian body plans. Nevertheless, precisely how and when segment polarity pathways arose remains obscure. Here, we demonstrate the molecular basis for segment polarization in developing larvae of the sea anemone Nematostella vectensis. Utilizing spatial transcriptomics, we first constructed a 3D gene expression atlas of developing larval segments. Capitalizing on accurate in silico predictions, we identified Lbx and Uncx, conserved homeodomain-containing genes that occupy opposing subsegmental domains under the control of both bone morphogenetic protein (BMP) signaling and the Hox-Gbx cascade. Functionally, Lbx mutagenesis eliminated all molecular evidence of segment polarization at the larval stage and caused an aberrant mirror-symmetric pattern of retractor muscles (RMs) in primary polyps. These results demonstrate the molecular basis for segment polarity in a non-bilaterian animal, suggesting that polarized metameric structures were present in the Cnidaria-Bilateria common ancestor over 600 million years ago.
Collapse
Affiliation(s)
- Shuonan He
- Stowers Institute for Medical Research, Kansas City, MO 64110, USA
| | - Wanqing Shao
- Department of Genetics, Washington University School of Medicine, St. Louis, MO 63110, USA; Edison Family Center for Genome Sciences and Systems Biology, Washington University School of Medicine, St. Louis, MO 63110, USA
| | | | - Ting Wang
- Department of Genetics, Washington University School of Medicine, St. Louis, MO 63110, USA; Edison Family Center for Genome Sciences and Systems Biology, Washington University School of Medicine, St. Louis, MO 63110, USA; McDonnell Genome Institute, Washington University School of Medicine, St. Louis, MO 63108, USA
| | - Matthew C Gibson
- Stowers Institute for Medical Research, Kansas City, MO 64110, USA; Department of Anatomy and Cell Biology, The University of Kansas School of Medicine, Kansas City, KS 66160, USA.
| |
Collapse
|
7
|
Jahn H, Hammel JU, Göpel T, Wirkner CS, Mayer G. A multiscale approach reveals elaborate circulatory system and intermittent heartbeat in velvet worms (Onychophora). Commun Biol 2023; 6:468. [PMID: 37117786 PMCID: PMC10147947 DOI: 10.1038/s42003-023-04797-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2022] [Accepted: 04/03/2023] [Indexed: 04/30/2023] Open
Abstract
An antagonistic hemolymph-muscular system is essential for soft-bodied invertebrates. Many ecdysozoans (molting animals) possess neither a heart nor a vascular or circulatory system, whereas most arthropods exhibit a well-developed circulatory system. How did this system evolve and how was it subsequently modified in panarthropod lineages? As the closest relatives of arthropods and tardigrades, onychophorans (velvet worms) represent a key group for addressing this question. We therefore analyzed the entire circulatory system of the peripatopsid Euperipatoides rowelli and discovered a surprisingly elaborate organization. Our findings suggest that the last common ancestor of Onychophora and Arthropoda most likely possessed an open vascular system, a posteriorly closed heart with segmental ostia, a pericardial sinus filled with nephrocytes and an impermeable pericardial septum, whereas the evolutionary origin of plical and pericardial channels is unclear. Our study further revealed an intermittent heartbeat-regular breaks of rhythmic, peristaltic contractions of the heart-in velvet worms, which might stimulate similar investigations in arthropods.
Collapse
Affiliation(s)
- Henry Jahn
- Department of Zoology, Institute of Biology, University of Kassel, Heinrich-Plett-Straße 40, D-34132, Kassel, Germany.
| | - Jörg U Hammel
- Institute of Materials Physics, Helmholtz-Zentrum Hereon at DESY, Notkestraße 85, D-22607, Hamburg, Germany
| | - Torben Göpel
- Multiscale Biology, Johann-Friedrich-Blumenbach Institut für Zoologie und Anthropologie, Georg-August-Universität Göttingen, Friedrich-Hund-Platz 1, D-37077, Göttingen, Germany
- Department of Biological Sciences, University of North Texas, 1155 Union Circle #305220, Denton, TX, 76203, USA
| | - Christian S Wirkner
- Institut für Allgemeine und Spezielle Zoologie, Institut für Biowissenschaften, Universität Rostock, Universitätsplatz 2, D-18055, Rostock, Germany
| | - Georg Mayer
- Department of Zoology, Institute of Biology, University of Kassel, Heinrich-Plett-Straße 40, D-34132, Kassel, Germany
| |
Collapse
|
8
|
He S, Shao W, Chen S(C, Wang T, Gibson MC. Spatial transcriptomics reveals a conserved segment polarity program that governs muscle patterning in Nematostella vectensis. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.01.09.523347. [PMID: 36711919 PMCID: PMC9882047 DOI: 10.1101/2023.01.09.523347] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
During early animal evolution, the emergence of axially-polarized segments was central to the diversification of complex bilaterian body plans. Nevertheless, precisely how and when segment polarity pathways arose remains obscure. Here we demonstrate the molecular basis for segment polarization in developing larvae of the pre-bilaterian sea anemone Nematostella vectensis . Utilizing spatial transcriptomics, we first constructed a 3-D gene expression atlas of developing larval segments. Capitalizing on accurate in silico predictions, we identified Lbx and Uncx, conserved homeodomain-containing genes that occupy opposing subsegmental domains under the control of both BMP signaling and the Hox-Gbx cascade. Functionally, Lbx mutagenesis eliminated all molecular evidence of segment polarization at larval stage and caused an aberrant mirror-symmetric pattern of retractor muscles in primary polyps. These results demonstrate the molecular basis for segment polarity in a pre-bilaterian animal, suggesting that polarized metameric structures were present in the Cnidaria-Bilateria common ancestor over 600 million years ago. Highlights Nematostella endomesodermal tissue forms metameric segments and displays a transcriptomic profile similar to that observed in bilaterian mesoderm Construction of a comprehensive 3-D gene expression atlas enables systematic dissection of segmental identity in endomesoderm Lbx and Uncx , two conserved homeobox-containing genes, establish segment polarity in Nematostella The Cnidarian-Bilaterian common ancestor likely possessed the genetic toolkit to generate polarized metameric structures.
Collapse
Affiliation(s)
- Shuonan He
- Stowers Institute for Medical Research, Kansas City, Missouri 64110, USA
- Current Address: Howard Hughes Medical Institute, Department of Organismic & Evolutionary Biology, Harvard University, 16 Divinity Avenue, Cambridge, Massachusetts 02138, USA
| | - Wanqing Shao
- Department of Genetics, Washington University School of Medicine, St. Louis, Missouri 63110, USA
- Edison Family Center for Genome Sciences and Systems Biology, Washington University School of Medicine, St. Louis, Missouri 63110, USA
- Current Address: Research Computing, Boston Children’s Hospital, 300 Longwood Avenue, Boston, Massachusetts 02115, USA
| | | | - Ting Wang
- Department of Genetics, Washington University School of Medicine, St. Louis, Missouri 63110, USA
- Edison Family Center for Genome Sciences and Systems Biology, Washington University School of Medicine, St. Louis, Missouri 63110, USA
- McDonnell Genome Institute, Washington University School of Medicine, St. Louis, Missouri 63108, USA
| | - Matthew C. Gibson
- Stowers Institute for Medical Research, Kansas City, Missouri 64110, USA
- Department of Anatomy and Cell Biology, The University of Kansas School of Medicine, Kansas City, Kansas 66160, USA
| |
Collapse
|
9
|
Martin C, Jahn H, Klein M, Hammel JU, Stevenson PA, Homberg U, Mayer G. The velvet worm brain unveils homologies and evolutionary novelties across panarthropods. BMC Biol 2022; 20:26. [PMID: 35073910 PMCID: PMC9136957 DOI: 10.1186/s12915-021-01196-w] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2020] [Accepted: 11/16/2021] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The evolution of the brain and its major neuropils in Panarthropoda (comprising Arthropoda, Tardigrada and Onychophora) remains enigmatic. As one of the closest relatives of arthropods, onychophorans are regarded as indispensable for a broad understanding of the evolution of panarthropod organ systems, including the brain, whose anatomical and functional organisation is often used to gain insights into evolutionary relations. However, while numerous recent studies have clarified the organisation of many arthropod nervous systems, a detailed investigation of the onychophoran brain with current state-of-the-art approaches is lacking, and further inconsistencies in nomenclature and interpretation hamper its understanding. To clarify the origins and homology of cerebral structures across panarthropods, we analysed the brain architecture in the onychophoran Euperipatoides rowelli by combining X-ray micro-computed tomography, histology, immunohistochemistry, confocal microscopy, and three-dimensional reconstruction. RESULTS Here, we use this detailed information to generate a consistent glossary for neuroanatomical studies of Onychophora. In addition, we report novel cerebral structures, provide novel details on previously known brain areas, and characterise further structures and neuropils in order to improve the reproducibility of neuroanatomical observations. Our findings support homology of mushroom bodies and central bodies in onychophorans and arthropods. Their antennal nerve cords and olfactory lobes most likely evolved independently. In contrast to previous reports, we found no evidence for second-order visual neuropils, or a frontal ganglion in the velvet worm brain. CONCLUSION We imaged the velvet worm nervous system at an unprecedented level of detail and compiled a comprehensive glossary of known and previously uncharacterised neuroanatomical structures to provide an in-depth characterisation of the onychophoran brain architecture. We expect that our data will improve the reproducibility and comparability of future neuroanatomical studies.
Collapse
Affiliation(s)
- Christine Martin
- Department of Zoology, Institute of Biology, University of Kassel, 34132, Kassel, Germany.
| | - Henry Jahn
- Department of Zoology, Institute of Biology, University of Kassel, 34132, Kassel, Germany
| | - Mercedes Klein
- Department of Zoology, Institute of Biology, University of Kassel, 34132, Kassel, Germany
| | - Jörg U Hammel
- Institute of Materials Physics, Helmholtz-Zentrum hereon, 21502, Geesthacht, Germany
| | - Paul A Stevenson
- Physiology of Animals and Behaviour, Institute of Biology, University of Leipzig, 04103, Leipzig, Germany
| | - Uwe Homberg
- Department of Biology, Animal Physiology, Philipps-Universität Marburg, 35043, Marburg, Germany
- Center for Mind, Brain and Behavior (CMBB), University of Marburg and Justus Liebig University Giessen, 35032, Marburg, Germany
| | - Georg Mayer
- Department of Zoology, Institute of Biology, University of Kassel, 34132, Kassel, Germany.
| |
Collapse
|
10
|
Chavarria RA, Game M, Arbelaez B, Ramnarine C, Snow ZK, Smith FW. Extensive loss of Wnt genes in Tardigrada. BMC Ecol Evol 2021; 21:223. [PMID: 34961481 PMCID: PMC8711157 DOI: 10.1186/s12862-021-01954-y] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2021] [Accepted: 12/09/2021] [Indexed: 11/28/2022] Open
Abstract
Background Wnt genes code for ligands that activate signaling pathways during development in Metazoa. Through the canonical Wnt (cWnt) signaling pathway, these genes regulate important processes in bilaterian development, such as establishing the anteroposterior axis and posterior growth. In Arthropoda, Wnt ligands also regulate segment polarity, and outgrowth and patterning of developing appendages. Arthropods are part of a lineage called Panarthropoda that includes Onychophora and Tardigrada. Previous studies revealed potential roles of Wnt genes in regulating posterior growth, segment polarity, and growth and patterning of legs in Onychophora. Unlike most other panarthropods, tardigrades lack posterior growth, but retain segmentation and appendages. Here, we investigated Wnt genes in tardigrades to gain insight into potential roles that these genes play during development of the highly compact and miniaturized tardigrade body plan. Results We analyzed published genomes for two representatives of Tardigrada, Hypsibius exemplaris and Ramazzottius varieornatus. We identified single orthologs of Wnt4, Wnt5, Wnt9, Wnt11, and WntA, as well as two Wnt16 paralogs in both tardigrade genomes. We only found a Wnt2 ortholog in H. exemplaris. We could not identify orthologs of Wnt1, Wnt6, Wnt7, Wnt8, or Wnt10. We identified most other components of cWnt signaling in both tardigrade genomes. However, we were unable to identify an ortholog of arrow/Lrp5/6, a gene that codes for a Frizzled co-receptor of Wnt ligands. Additionally, we found that some other animals that have lost several Wnt genes and are secondarily miniaturized, like tardigrades, are also missing an ortholog of arrow/Lrp5/6. We analyzed the embryonic expression patterns of Wnt genes in H. exemplaris during developmental stages that span the establishment of the AP axis through segmentation and leg development. We detected expression of all Wnt genes in H. exemplaris besides one of the Wnt16 paralogs. During embryo elongation, expression of several Wnt genes was restricted to the posterior pole or a region between the anterior and posterior poles. Wnt genes were expressed in distinct patterns during segmentation and development of legs in H. exemplaris, rather than in broadly overlapping patterns. Conclusions Our results indicate that Wnt signaling has been highly modified in Tardigrada. While most components of cWnt signaling are conserved in tardigrades, we conclude that tardigrades have lost Wnt1, Wnt6, Wnt7, Wnt8, and Wnt10, along with arrow/Lrp5/6. Our expression data may indicate a conserved role of Wnt genes in specifying posterior identities during establishment of the AP axis. However, the loss of several Wnt genes and the distinct expression patterns of Wnt genes during segmentation and leg development may indicate that combinatorial interactions among Wnt genes are less important during tardigrade development compared to many other animals. Based on our results, and comparisons to previous studies, we speculate that the loss of several Wnt genes in Tardigrada may be related to a reduced number of cells and simplified development that accompanied miniaturization and anatomical simplification in this lineage. Supplementary Information The online version contains supplementary material available at 10.1186/s12862-021-01954-y.
Collapse
Affiliation(s)
- Raul A Chavarria
- Biology Department, University of North Florida, Jacksonville, FL, USA
| | - Mandy Game
- Biology Department, University of North Florida, Jacksonville, FL, USA
| | - Briana Arbelaez
- Biology Department, University of North Florida, Jacksonville, FL, USA
| | - Chloe Ramnarine
- Biology Department, University of North Florida, Jacksonville, FL, USA
| | - Zachary K Snow
- Biology Department, University of North Florida, Jacksonville, FL, USA
| | - Frank W Smith
- Biology Department, University of North Florida, Jacksonville, FL, USA.
| |
Collapse
|
11
|
Mauer KM, Schmidt H, Dittrich M, Fröbius AC, Hellmann SL, Zischler H, Hankeln T, Herlyn H. Genomics and transcriptomics of epizoic Seisonidea (Rotifera, syn. Syndermata) reveal strain formation and gradual gene loss with growing ties to the host. BMC Genomics 2021; 22:604. [PMID: 34372786 PMCID: PMC8351084 DOI: 10.1186/s12864-021-07857-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2021] [Accepted: 06/28/2021] [Indexed: 11/20/2022] Open
Abstract
Background Seisonidea (also Seisonacea or Seisonidae) is a group of small animals living on marine crustaceans (Nebalia spec.) with only four species described so far. Its monophyletic origin with mostly free-living wheel animals (Monogononta, Bdelloidea) and endoparasitic thorny-headed worms (Acanthocephala) is widely accepted. However, the phylogenetic relationships inside the Rotifera-Acanthocephala clade (Rotifera sensulato or Syndermata) are subject to ongoing debate, with consequences for our understanding of how genomes and lifestyles might have evolved. To gain new insights, we analyzed first drafts of the genome and transcriptome of the key taxon Seisonidea. Results Analyses of gDNA-Seq and mRNA-Seq data uncovered two genetically distinct lineages in Seison nebaliae Grube, 1861 off the French Channel coast. Their mitochondrial haplotypes shared only 82% sequence identity despite identical gene order. In the nuclear genome, distinct linages were reflected in different gene compactness, GC content and codon usage. The haploid nuclear genome spans ca. 46 Mb, of which 96% were reconstructed. According to ~ 23,000 SuperTranscripts, gene number in S. nebaliae should be within the range published for other members of Rotifera-Acanthocephala. Consistent with this, numbers of metazoan core orthologues and ANTP-type transcriptional regulatory genes in the S. nebaliae genome assembly were between the corresponding numbers in the other assemblies analyzed. We additionally provide evidence that a basal branching of Seisonidea within Rotifera-Acanthocephala could reflect attraction to the outgroup. Accordingly, rooting via a reconstructed ancestral sequence led to monophyletic Pararotatoria (Seisonidea+Acanthocephala) within Hemirotifera (Bdelloidea+Pararotatoria). Conclusion Matching genome/transcriptome metrics with the above phylogenetic hypothesis suggests that a haploid nuclear genome of about 50 Mb represents the plesiomorphic state for Rotifera-Acanthocephala. Smaller genome size in S. nebaliae probably results from subsequent reduction. In contrast, genome size should have increased independently in monogononts as well as bdelloid and acanthocephalan stem lines. The present data additionally indicate a decrease in gene repertoire from free-living to epizoic and endoparasitic lifestyles. Potentially, this reflects corresponding steps from the root of Rotifera-Acanthocephala via the last common ancestors of Hemirotifera and Pararotatoria to the one of Acanthocephala. Lastly, rooting via a reconstructed ancestral sequence may prove useful in phylogenetic analyses of other deep splits. Supplementary Information The online version contains supplementary material available at 10.1186/s12864-021-07857-y.
Collapse
Affiliation(s)
- Katharina M Mauer
- Institute of Organismic and Molecular Evolution (iomE), Anthropology, Johannes Gutenberg University Mainz, Mainz, Germany.
| | - Hanno Schmidt
- Institute of Organismic and Molecular Evolution (iomE), Anthropology, Johannes Gutenberg University Mainz, Mainz, Germany
| | - Marco Dittrich
- Institute of Organismic and Molecular Evolution (iomE), Anthropology, Johannes Gutenberg University Mainz, Mainz, Germany
| | - Andreas C Fröbius
- Molecular Andrology, Biomedical Research Center Seltersberg (BFS), Justus Liebig University Gießen, Giessen, Germany
| | - Sören Lukas Hellmann
- Institute of Organismic and Molecular Evolution (iomE), Molecular Genetics and Genomic Analysis Group, Johannes Gutenberg University Mainz, Mainz, Germany
| | - Hans Zischler
- Institute of Organismic and Molecular Evolution (iomE), Anthropology, Johannes Gutenberg University Mainz, Mainz, Germany
| | - Thomas Hankeln
- Institute of Organismic and Molecular Evolution (iomE), Molecular Genetics and Genomic Analysis Group, Johannes Gutenberg University Mainz, Mainz, Germany
| | - Holger Herlyn
- Institute of Organismic and Molecular Evolution (iomE), Anthropology, Johannes Gutenberg University Mainz, Mainz, Germany.
| |
Collapse
|
12
|
Janssen R, Budd GE. Oscillating waves of Fox, Cyclin and CDK gene expression indicate unique spatiotemporal control of cell cycling during nervous system development in onychophorans. ARTHROPOD STRUCTURE & DEVELOPMENT 2021; 62:101042. [PMID: 33752095 DOI: 10.1016/j.asd.2021.101042] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/16/2020] [Revised: 02/04/2021] [Accepted: 02/05/2021] [Indexed: 06/12/2023]
Abstract
Forkhead box (Fox) genes code for a class of transcription factors with many different fundamental functions in animal development including cell cycle control. Other important factors of cell cycle control are Cyclins and Cyclin-dependent kinases (CDKs). Here we report on the oscillating expression of three Fox genes, FoxM, FoxN14 (jumeaux) and FoxN23 (Checkpoint suppressor like-1), Cyclins and CDKs in an onychophoran, a representative of a relatively small group of animals that are closely related to the arthropods. Expression of these genes is in the form of several waves that start as dot-like domains in the center of each segment and then transform into concentric rings that run towards the periphery of the segments. This oscillating gene expression, however, occurs exclusively along the anterior-posterior body axis in the tissue ventral to the base of the appendages, a region where the central nervous system and the enigmatic ventral and preventral organs of the onychophoran develop. We suggest that the oscillating gene expression and the resulting waves of expression we report are likely correlated with cell cycle control during the development of the onychophoran nervous system. This intriguing patterning appears to be unique for onychophorans as it is not found in any of the arthropods we also investigated in this study, and is likely correlated with the slow embryonic development of onychophorans compared to arthropods.
Collapse
Affiliation(s)
- Ralf Janssen
- Uppsala University, Department of Earth Sciences, Palaeobiology, Villavägen 16, 75236 Uppsala, Sweden.
| | - Graham E Budd
- Uppsala University, Department of Earth Sciences, Palaeobiology, Villavägen 16, 75236 Uppsala, Sweden
| |
Collapse
|
13
|
Sevigny JL, Norenburg JL, Leasi F. A Bioinformatics Tutorial for Comparative Development Genomics in Diverse Meiofauna. Methods Mol Biol 2021; 2219:289-305. [PMID: 33074549 DOI: 10.1007/978-1-0716-0974-3_19] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Miniaturization, which is a common feature in animals, is particularly manifest in meiofauna-animals sharing peculiar phenotypic features that evolved as adaptations to the highly specialized aquatic interstitial habitat. While revealing much about the extreme phyletic diversity of meiofauna, the genome structure of meiofaunal species could also characterize the phenotype of ancestral states as well as explain the origin and evolution of miniaturization. Here, we present a practical bioinformatics tutorial for genome assembly, genome comparison, and characterization of Hox clusters in meiofaunal species.
Collapse
Affiliation(s)
- Joseph L Sevigny
- Hubbard Center for Genome Studies, Department of Molecular, Cellular, and Biomedical Sciences, University of New Hampshire, Durham, NH, USA
| | - Jon L Norenburg
- Department of Invertebrate Zoology, Smithsonian National Museum of Natural History, Washington, DC, USA
| | - Francesca Leasi
- Department of Biology, Geology and Environmental Science, University of Tennessee at Chattanooga, Chattanooga, TN, USA.
| |
Collapse
|
14
|
England SJ, Cerda GA, Kowalchuk A, Sorice T, Grieb G, Lewis KE. Hmx3a Has Essential Functions in Zebrafish Spinal Cord, Ear and Lateral Line Development. Genetics 2020; 216:1153-1185. [PMID: 33077489 PMCID: PMC7768253 DOI: 10.1534/genetics.120.303748] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2020] [Accepted: 10/14/2020] [Indexed: 11/30/2022] Open
Abstract
Transcription factors that contain a homeodomain DNA-binding domain have crucial functions in most aspects of cellular function and embryonic development in both animals and plants. Hmx proteins are a subfamily of NK homeodomain-containing proteins that have fundamental roles in development of sensory structures such as the eye and the ear. However, Hmx functions in spinal cord development have not been analyzed. Here, we show that zebrafish (Danio rerio) hmx2 and hmx3a are coexpressed in spinal dI2 and V1 interneurons, whereas hmx3b, hmx1, and hmx4 are not expressed in spinal cord. Using mutational analyses, we demonstrate that, in addition to its previously reported role in ear development, hmx3a is required for correct specification of a subset of spinal interneuron neurotransmitter phenotypes, as well as correct lateral line progression and survival to adulthood. Surprisingly, despite similar expression patterns of hmx2 and hmx3a during embryonic development, zebrafish hmx2 mutants are viable and have no obviously abnormal phenotypes in sensory structures or neurons that require hmx3a In addition, embryos homozygous for deletions of both hmx2 and hmx3a have identical phenotypes to severe hmx3a single mutants. However, mutating hmx2 in hypomorphic hmx3a mutants that usually develop normally, results in abnormal ear and lateral line phenotypes. This suggests that while hmx2 cannot compensate for loss of hmx3a, it does function in these developmental processes, although to a much lesser extent than hmx3a More surprisingly, our mutational analyses suggest that Hmx3a may not require its homeodomain DNA-binding domain for its roles in viability or embryonic development.
Collapse
Affiliation(s)
| | - Gustavo A Cerda
- Department of Physiology, Development and Neuroscience, University of Cambridge, CB2 3DY, UK
| | | | - Taylor Sorice
- Department of Biology, Syracuse University, New York 13244
| | - Ginny Grieb
- Department of Biology, Syracuse University, New York 13244
| | | |
Collapse
|
15
|
Martin C, Hering L, Metzendorf N, Hormann S, Kasten S, Fuhrmann S, Werckenthin A, Herberg FW, Stengl M, Mayer G. Analysis of Pigment-Dispersing Factor Neuropeptides and Their Receptor in a Velvet Worm. Front Endocrinol (Lausanne) 2020; 11:273. [PMID: 32477266 PMCID: PMC7235175 DOI: 10.3389/fendo.2020.00273] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/17/2020] [Accepted: 04/14/2020] [Indexed: 11/13/2022] Open
Abstract
Pigment-dispersing factor neuropeptides (PDFs) occur in a wide range of protostomes including ecdysozoans (= molting animals) and lophotrochozoans (mollusks, annelids, flatworms, and allies). Studies in insects revealed that PDFs play a role as coupling factors of circadian pacemaker cells, thereby controlling rest-activity rhythms. While the last common ancestor of protostomes most likely possessed only one pdf gene, two pdf homologs, pdf-I and pdf-II, might have been present in the last common ancestors of Ecdysozoa and Panarthropoda (Onychophora + Tardigrada + Arthropoda). One of these homologs, however, was subsequently lost in the tardigrade and arthropod lineages followed by independent duplications of pdf-I in tardigrades and decapod crustaceans. Due to the ancestral set of two pdf genes, the study of PDFs and their receptor (PDFR) in Onychophora might reveal the ancient organization and function of the PDF/PDFR system in panarthropods. Therefore, we deorphanized the PDF receptor and generated specific antibodies to localize the two PDF peptides and their receptor in the onychophoran Euperipatoides rowelli. We further conducted bioluminescence resonance energy transfer (BRET) experiments on cultured human cells (HEK293T) using an Epac-based sensor (Epac-L) to examine cAMP responses in transfected cells and to reveal potential differences in the interaction of PDF-I and PDF-II with PDFR from E. rowelli. These data show that PDF-II has a tenfold higher potency than PDF-I as an activating ligand. Double immunolabeling revealed that both peptides are co-expressed in E. rowelli but their respective levels of expression differ between specific cells: some neurons express the same amount of both peptides, while others exhibit higher levels of either PDF-I or PDF-II. The detection of the onychophoran PDF receptor in cells that additionally express the two PDF peptides suggests autoreception, whereas spatial separation of PDFR- and PDF-expressing cells supports hormonal release of PDF into the hemolymph. This suggests a dual role of PDF peptides-as hormones and as neurotransmitters/neuromodulators-in Onychophora.
Collapse
Affiliation(s)
- Christine Martin
- Department of Zoology, Institute of Biology, University of Kassel, Kassel, Germany
| | - Lars Hering
- Department of Zoology, Institute of Biology, University of Kassel, Kassel, Germany
| | - Niklas Metzendorf
- Department of Zoology, Institute of Biology, University of Kassel, Kassel, Germany
| | - Sarah Hormann
- Department of Zoology, Institute of Biology, University of Kassel, Kassel, Germany
| | - Sonja Kasten
- Department of Zoology, Institute of Biology, University of Kassel, Kassel, Germany
| | - Sonja Fuhrmann
- Department of Zoology, Institute of Biology, University of Kassel, Kassel, Germany
| | - Achim Werckenthin
- Department of Animal Physiology, Institute of Biology, University of Kassel, Kassel, Germany
| | - Friedrich W. Herberg
- Department of Biochemistry, Institute of Biology, University of Kassel, Kassel, Germany
| | - Monika Stengl
- Department of Animal Physiology, Institute of Biology, University of Kassel, Kassel, Germany
| | - Georg Mayer
- Department of Zoology, Institute of Biology, University of Kassel, Kassel, Germany
- *Correspondence: Georg Mayer
| |
Collapse
|
16
|
Oliveira IDS, Kumerics A, Jahn H, Müller M, Pfeiffer F, Mayer G. Functional morphology of a lobopod: case study of an onychophoran leg. ROYAL SOCIETY OPEN SCIENCE 2019; 6:191200. [PMID: 31824728 PMCID: PMC6837196 DOI: 10.1098/rsos.191200] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/10/2019] [Accepted: 09/09/2019] [Indexed: 05/08/2023]
Abstract
Segmental, paired locomotory appendages are a characteristic feature of Panarthropoda-a diversified clade of moulting animals that includes onychophorans (velvet worms), tardigrades (water bears) and arthropods. While arthropods acquired a sclerotized exoskeleton and articulated limbs, onychophorans and tardigrades possess a soft body and unjointed limbs called lobopods, which they inherited from Cambrian lobopodians. To date, the origin and ancestral structure of the lobopods and their transformation into the jointed appendages are all poorly understood. We therefore combined high-resolution computed tomography with high-speed camera recordings to characterize the functional anatomy of a trunk lobopod from the onychophoran Euperipatoides rowelli. Three-dimensional reconstruction of the complete set of muscles and muscle fibres as well as non-muscular structures revealed the spatial relationship and relative volumes of the muscular, excretory, circulatory and nervous systems within the leg. Locomotory movements of individual lobopods of E. rowelli proved far more diverse than previously thought and might be governed by a complex interplay of 15 muscles, including one promotor, one remotor, one levator, one retractor, two depressors, two rotators, one flexor and two constrictors as well as muscles for stabilization and haemolymph control. We discuss the implications of our findings for understanding the evolution of locomotion in panarthropods.
Collapse
Affiliation(s)
- Ivo de Sena Oliveira
- Department of Zoology, Institute of Biology, University of Kassel, Kassel, Germany
- Departamento de Zoologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
| | - Andreas Kumerics
- Department of Zoology, Institute of Biology, University of Kassel, Kassel, Germany
| | - Henry Jahn
- Department of Zoology, Institute of Biology, University of Kassel, Kassel, Germany
| | - Mark Müller
- Chair of Biomedical Physics, Department of Physics and Munich School of Bioengineering, Technical University of Munich, Garching, Germany
| | - Franz Pfeiffer
- Chair of Biomedical Physics, Department of Physics and Munich School of Bioengineering, Technical University of Munich, Garching, Germany
- Department of Diagnostic and Interventional Radiology, Klinikum rechts der Isar, Technical University of Munich, 81675 München, Germany
| | - Georg Mayer
- Department of Zoology, Institute of Biology, University of Kassel, Kassel, Germany
| |
Collapse
|
17
|
Treffkorn S, Hernández-Lagos OY, Mayer G. Evidence for cell turnover as the mechanism responsible for the transport of embryos towards the vagina in viviparous onychophorans (velvet worms). Front Zool 2019; 16:16. [PMID: 31182967 PMCID: PMC6555992 DOI: 10.1186/s12983-019-0317-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2019] [Accepted: 05/13/2019] [Indexed: 12/15/2022] Open
Abstract
Background Onychophorans, commonly known as velvet worms, display a remarkable diversity of reproductive strategies including oviparity, and placentotrophic, lecithotrophic, matrotrophic or combined lecithotrophic/matrotrophic viviparity. In the placentotrophic species, the embryos of consecutive developmental stages are attached to the uterus via a placental stalk, suggesting they might be transported passively towards the vagina due to proximal growth and distal degeneration of tissue. However, this assumption has never been tested using specific markers. We therefore analyzed the patterns of cell proliferation and apoptosis in the genital tracts of two placentotrophic peripatids from Colombia and a non-placentotrophic peripatopsid from Australia. Results All three species show a high number of apoptotic cells in the distal portion of the genital tract near the genital opening. In the two placentotrophic species, additional apoptotic cells appear in ring-like vestigial placentation zones of late embryonic chambers. While moderate cell proliferation occurs along the entire uterus in all three species, only the two placentotrophic species show a distinct proliferation zone near the ovary as well as in the ring-like implantation zone of the first embryonic chamber. In contrast to the two placentotrophic species, the non-placentotrophic species clearly does not show such regions of high proliferation in the uterus but exhibits proliferating and apoptotic cells in the ovarian stalks. While cell proliferation mainly occurs in stalks carrying maturating oocytes, apoptosis is restricted to stalks whose oocytes have been released into the ovarian lumen. Conclusions Our results confirm the hypothesis that the uterus of placentotrophic onychophorans grows proximally but is resorbed distally. This is supported by the detection of a proximal proliferation zone and a distal degenerative zone in the two placentotrophic species. Hence, cell turnover might be responsible for the transport of their embryos towards the vagina, analogous to a conveyor belt. Surprisingly, the distal degenerative zone is also found in the non-placentotrophic species, in which cell turnover was unexpected. These findings suggest that the distal degenerative zone is an ancestral feature of Onychophora, whereas the proximal proliferation zone might have evolved in the last common ancestor of the placentotrophic Peripatidae. Electronic supplementary material The online version of this article (10.1186/s12983-019-0317-x) contains supplementary material, which is available to authorized users.
Collapse
Affiliation(s)
- Sandra Treffkorn
- 1Department of Zoology, Institute of Biology, University of Kassel, Heinrich-Plett-Str. 40, D-34132 Kassel, Germany
| | - Oscar Yesid Hernández-Lagos
- 2Laboratorio de Biología Molecular, Escuela de Biología, Universidad Industrial de Santander, Carrera 27 #9, ciudad Universitaria, Bucaramanga, Santander Colombia
| | - Georg Mayer
- 1Department of Zoology, Institute of Biology, University of Kassel, Heinrich-Plett-Str. 40, D-34132 Kassel, Germany
| |
Collapse
|
18
|
Treffkorn S, Mayer G. Expression of NK genes that are not part of the NK cluster in the onychophoran Euperipatoides rowelli (Peripatopsidae). BMC DEVELOPMENTAL BIOLOGY 2019; 19:7. [PMID: 30987579 PMCID: PMC6466738 DOI: 10.1186/s12861-019-0185-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/30/2018] [Accepted: 03/12/2019] [Indexed: 12/25/2022]
Abstract
Background NK genes are a group of homeobox transcription factors that are involved in various molecular pathways across bilaterians. They are typically divided into two subgroups, the NK cluster (NKC) and NK-linked genes (NKL). While the NKC genes have been studied in various bilaterians, corresponding data of many NKL genes are missing to date. To further investigate the ancestral roles of NK family genes, we analyzed the expression patterns of NKL genes in the onychophoran Euperipatoides rowelli. Results The NKL gene complement of E. rowelli comprises eight genes, including BarH, Bari, Emx, Hhex, Nedx, NK2.1, vax and NK2.2, of which only NK2.2 was studied previously. Our data for the remaining seven NKL genes revealed expression in different structures associated with the developing nervous system in embryos of E. rowelli. While NK2.1 and vax are expressed in distinct medial regions of the developing protocerebrum early in development, BarH, Bari, Emx, Hhex and Nedx are expressed in late developmental stages, after all major structures of the nervous system have been established. Furthermore, BarH and Nedx are expressed in distinct mesodermal domains in the developing limbs. Conclusions Comparison of our expression data to those of other bilaterians revealed similar patterns of NK2.1, vax, BarH and Emx in various aspects of neural development, such as the formation of anterior neurosecretory cells mediated by a conserved molecular mechanism including NK2.1 and vax, and the development of the central and peripheral nervous system involving BarH and Emx. A conserved role in neural development has also been reported from NK2.2, suggesting that the NKL genes might have been primarily involved in neural development in the last common ancestor of bilaterians or at least nephrozoans (all bilaterians excluding xenacoelomorphs). The lack of comparative data for many of the remaining NKL genes, including Bari, Hhex and Nedx currently hampers further evolutionary conclusions. Hence, future studies should focus on the expression of these genes in other bilaterians, which would provide a basis for comparative studies and might help to better understand the role of NK genes in the diversification of bilaterians. Electronic supplementary material The online version of this article (10.1186/s12861-019-0185-9) contains supplementary material, which is available to authorized users.
Collapse
Affiliation(s)
- Sandra Treffkorn
- Department of Zoology, Institute of Biology, University of Kassel, Kassel, Germany.
| | - Georg Mayer
- Department of Zoology, Institute of Biology, University of Kassel, Kassel, Germany
| |
Collapse
|
19
|
Hou X, Wei M, Li Q, Zhang T, Zhou D, Kong D, Xie Y, Qin Z, Zhang Z. Transcriptome Analysis of Larval Segment Formation and Secondary Loss in the Echiuran Worm Urechis unicinctus. Int J Mol Sci 2019; 20:E1806. [PMID: 31013695 PMCID: PMC6514800 DOI: 10.3390/ijms20081806] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2019] [Revised: 03/23/2019] [Accepted: 04/10/2019] [Indexed: 01/06/2023] Open
Abstract
The larval segment formation and secondary loss in echiurans is a special phenomenon, which is considered to be one of the important characteristics in the evolutionary relationship between the Echiura and Annelida. To better understand the molecular mechanism of this phenomenon, we revealed the larval transcriptome profile of the echiuran worm Urechis unicinctus using RNA-Seq technology. Twelve cDNA libraries of U. unicinctus larvae, late-trochophore (LT), early-segmentation larva (ES), segmentation larva (SL), and worm-shaped larva (WL) were constructed. Totally 243,381 unigenes were assembled with an average length of 1125 bp and N50 of 1836 bp, and 149,488 unigenes (61.42%) were annotated. We obtained 70,517 differentially expressed genes (DEGs) by pairwise comparison of the larval transcriptome data at different developmental stages and clustered them into 20 gene expression profiles using STEM software. Based on the typical profiles during the larval segment formation and secondary loss, eight signaling pathways were enriched, and five of which, mTOR, PI3K-AKT, TGF-β, MAPK, and Dorso-ventral axis formation signaling pathway, were proposed for the first time to be involved in the segment formation. Furthermore, we identified 119 unigenes related to the segment formation of annelids, arthropods, and chordates, in which 101 genes were identified in Drosophila and annelids. The function of most segment polarity gene homologs (hedgehog, wingless, engrailed, etc.) was conserved in echiurans, annelids, and arthropods based on their expression profiles, while the gap and pair-rule gene homologs were not. Finally, we verified that strong positive signals of Hedgehog were indeed located on the boundary of larval segments using immunofluorescence. Data in this study provide molecular evidence for the understanding of larval segment development in echiurans and may serve as a blueprint for segmented ancestors in future research.
Collapse
Affiliation(s)
- Xitan Hou
- College of Marine Life Sciences, Ocean University of China, Qingdao 266003, China.
| | - Maokai Wei
- College of Marine Life Sciences, Ocean University of China, Qingdao 266003, China.
| | - Qi Li
- College of Marine Life Sciences, Ocean University of China, Qingdao 266003, China.
| | - Tingting Zhang
- College of Marine Life Sciences, Ocean University of China, Qingdao 266003, China.
| | - Di Zhou
- College of Marine Life Sciences, Ocean University of China, Qingdao 266003, China.
| | - Dexu Kong
- College of Marine Life Sciences, Ocean University of China, Qingdao 266003, China.
| | - Yueyang Xie
- College of Marine Life Sciences, Ocean University of China, Qingdao 266003, China.
| | - Zhenkui Qin
- College of Marine Life Sciences, Ocean University of China, Qingdao 266003, China.
| | - Zhifeng Zhang
- College of Marine Life Sciences, Ocean University of China, Qingdao 266003, China.
| |
Collapse
|
20
|
Gross V, Treffkorn S, Reichelt J, Epple L, Lüter C, Mayer G. Miniaturization of tardigrades (water bears): Morphological and genomic perspectives. ARTHROPOD STRUCTURE & DEVELOPMENT 2019; 48:12-19. [PMID: 30447338 DOI: 10.1016/j.asd.2018.11.006] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/27/2018] [Revised: 11/08/2018] [Accepted: 11/13/2018] [Indexed: 05/03/2023]
Abstract
Tardigrades form a monophyletic group of microscopic ecdysozoans best known for surviving extreme environmental conditions. Due to their key phylogenetic position as a subgroup of the Panarthropoda, understanding tardigrade biology is important for comparative studies with related groups like Arthropoda. Panarthropods - and Ecdysozoa as a whole - likely evolved from macroscopic ancestors, with several taxa becoming secondarily miniaturized. Morphological and genomic evidence likewise points to a miniaturized tardigrade ancestor. The five-segmented tardigrade body typically measures less than 1 mm in length and consists of only about 1000 cells. Most organs comprise a relatively small number of cells, with the highest proportion belonging to the central nervous system, while muscles are reduced to a single cell each. Similarly, fully sequenced genomes of three tardigrade species - together with Hox gene expression data - point to extensive modifications, rearrangements, and major losses of genes and even a large body region. Parallels are evident with related ecdysozoans that may have also undergone genomic reductions, such as the nematode Caenorhabditis elegans. We interpret these data together as evidence of miniaturization in the tardigrade lineage, while cautioning that the effects of miniaturization may manifest in different ways depending on the organ or organ system under examination.
Collapse
Affiliation(s)
- Vladimir Gross
- Department of Zoology, Institute of Biology, University of Kassel, Heinrich-Plett-Straße 40, Kassel, D-34132, Germany
| | - Sandra Treffkorn
- Department of Zoology, Institute of Biology, University of Kassel, Heinrich-Plett-Straße 40, Kassel, D-34132, Germany
| | - Julian Reichelt
- Department of Zoology, Institute of Biology, University of Kassel, Heinrich-Plett-Straße 40, Kassel, D-34132, Germany
| | - Lisa Epple
- Department of Zoology, Institute of Biology, University of Kassel, Heinrich-Plett-Straße 40, Kassel, D-34132, Germany
| | - Carsten Lüter
- Museum für Naturkunde, Leibniz-Institute for Evolution and Biodiversity Science, Invalidenstraße 43, Berlin, D-10115, Germany
| | - Georg Mayer
- Department of Zoology, Institute of Biology, University of Kassel, Heinrich-Plett-Straße 40, Kassel, D-34132, Germany.
| |
Collapse
|
21
|
Zhao D, Chen S, Liu X. Lateral neural borders as precursors of peripheral nervous systems: A comparative view across bilaterians. Dev Growth Differ 2018; 61:58-72. [DOI: 10.1111/dgd.12585] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2018] [Revised: 11/14/2018] [Accepted: 11/14/2018] [Indexed: 01/13/2023]
Affiliation(s)
- Di Zhao
- School of Life Sciences; Capital Normal University; Beijing China
- Ministry of Education Key Laboratory of Bioinformatics; Center for Synthetic and Systems Biology; School of Life Sciences; Tsinghua University; Beijing China
| | - Siyu Chen
- Ministry of Education Key Laboratory of Bioinformatics; Center for Synthetic and Systems Biology; School of Life Sciences; Tsinghua University; Beijing China
| | - Xiao Liu
- School of Life Sciences; Capital Normal University; Beijing China
- Ministry of Education Key Laboratory of Bioinformatics; Center for Synthetic and Systems Biology; School of Life Sciences; Tsinghua University; Beijing China
| |
Collapse
|