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Wang R, Leite DJ, Karadas L, Schiffer PH, Pechmann M. FGF signalling is involved in cumulus migration in the common house spider Parasteatoda tepidariorum. Dev Biol 2023; 494:35-45. [PMID: 36470448 DOI: 10.1016/j.ydbio.2022.11.009] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2022] [Revised: 11/28/2022] [Accepted: 11/30/2022] [Indexed: 12/12/2022]
Abstract
Cell migration is a fundamental component during the development of most multicellular organisms. In the early spider embryo, the collective migration of signalling cells, known as the cumulus, is required to set the dorsoventral body axis. Here, we show that FGF signalling plays an important role during cumulus migration in the spider Parasteatoda tepidariorum. Spider embryos with reduced FGF signalling show reduced or absent cumulus migration and display dorsoventral patterning defects. Our study reveals that the transcription factor Ets4 regulates the expression of several FGF signalling components in the cumulus. In conjunction with a previous study, we show that the expression of fgf8 in the germ-disc is regulated via the Hedgehog signalling pathway. We also demonstrate that FGF signalling influences the BMP signalling pathway activity in the region around cumulus cells. Finally, we show that FGFR signalling might also influence cumulus migration in basally branching spiders and we propose that fgf8 might act as a chemo-attractant to guide cumulus cells towards the future dorsal pole of the spider embryo.
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Affiliation(s)
- Ruixun Wang
- Institute for Zoology/Developmental Biology, Biocenter, University of Cologne, Zuelpicher Str. 47b, 50674, Cologne, Germany
| | - Daniel J Leite
- Department of Biosciences, Durham University, Durham, DH1 3LE, UK
| | - Linda Karadas
- Institute for Zoology/Developmental Biology, Biocenter, University of Cologne, Zuelpicher Str. 47b, 50674, Cologne, Germany
| | - Philipp H Schiffer
- Institute for Zoology/Developmental Biology, Biocenter, University of Cologne, Zuelpicher Str. 47b, 50674, Cologne, Germany
| | - Matthias Pechmann
- Institute for Zoology/Developmental Biology, Biocenter, University of Cologne, Zuelpicher Str. 47b, 50674, Cologne, Germany.
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Prpic NM, Pechmann M. Extraembryonic tissue in chelicerates: a review and outlook. Philos Trans R Soc Lond B Biol Sci 2022; 377:20210269. [PMID: 36252223 PMCID: PMC9574639 DOI: 10.1098/rstb.2021.0269] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2021] [Accepted: 04/16/2022] [Indexed: 01/03/2023] Open
Abstract
The formation of extraembryonic membranes (EEMs) contributes to the proper development of many animals. In arthropods, the formation and function of EEMs have been studied best in insects. Regarding the development of extraembryonic tissue in chelicerates (spiders and relatives), most information is available for spiders (Araneae). Especially two populations of cells have been considered to represent EEMs in spiders. The first of these potential EEMs develops shortly after egg deposition, opposite to a radially symmetrical germ disc that forms in one hemisphere of the egg and encloses the yolk. The second tissue, which has been described as being extraembryonic is the so-called dorsal field, which is required to cover the dorsal part of the developing spider germ rudiment before proper dorsal closure. In this review, we summarize the current knowledge regarding the formation of potential extraembryonic structures in the Chelicerata. We describe the early embryogenesis of spiders and other chelicerates, with a special focus on the formation of the potential extraembryonic tissues. This article is part of the theme issue 'Extraembryonic tissues: exploring concepts, definitions and functions across the animal kingdom'.
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Affiliation(s)
- Nikola-Michael Prpic
- Justus-Liebig-Universitaet Giessen, Institut für Allgemeine Zoologie und Entwicklungsbiologie, AG Zoologie mit dem Schwerpunkt Molekulare Entwicklungsbiologie, Heinrich-Buff-Ring 38, 35392 Giessen, Germany
| | - Matthias Pechmann
- Institute for Zoology, University of Cologne, Biocenter, Zuelpicher Strasse 47b, 50674 Cologne, Germany
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Iwasaki-Yokozawa S, Nanjo R, Akiyama-Oda Y, Oda H. Lineage-specific, fast-evolving GATA-like gene regulates zygotic gene activation to promote endoderm specification and pattern formation in the Theridiidae spider. BMC Biol 2022; 20:223. [PMID: 36203191 PMCID: PMC9535882 DOI: 10.1186/s12915-022-01421-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2022] [Accepted: 09/27/2022] [Indexed: 11/23/2022] Open
Abstract
Background
The process of early development varies across the species-rich phylum Arthropoda. Owing to the limited research strategies for dissecting lineage-specific processes of development in arthropods, little is known about the variations in early arthropod development at molecular resolution. The Theridiidae spider, Parasteatoda tepidariorum, has its genome sequenced and could potentially contribute to dissecting early embryonic processes. Results We present genome-wide identification of candidate genes that exhibit locally restricted expression in germ disc forming stage embryos of P. tepidariorum, based on comparative transcriptomes of isolated cells from different regions of the embryo. A subsequent pilot screen by parental RNA interference identifies three genes required for body axis formation. One of them is a GATA-like gene that has been fast evolving after duplication and divergence from a canonical GATA family gene. This gene is designated fuchi nashi (fuchi) after its knockdown phenotypes, where the cell movement toward the formation of a germ disc was reversed. fuchi expression occurs in cells outside a forming germ disc and persists in the endoderm. Transcriptome and chromatin accessibility analyses of fuchi pRNAi embryos suggest that early fuchi activity regulates chromatin state and zygotic gene activation to promote endoderm specification and pattern formation. We also show that there are many uncharacterized genes regulated by fuchi. Conclusions Our genome-based research using an arthropod phylogenetically distant from Drosophila identifies a lineage-specific, fast-evolving gene with key developmental roles in one of the earliest, genome-wide regulatory events, and allows for molecular exploration of the developmental variations in early arthropod embryos. Supplementary Information The online version contains supplementary material available at 10.1186/s12915-022-01421-0.
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Affiliation(s)
- Sawa Iwasaki-Yokozawa
- Laboratory of Evolutionary Cell and Developmental Biology, JT Biohistory Research Hall, Takatsuki, Osaka, 569-1125, Japan
| | - Ryota Nanjo
- Laboratory of Evolutionary Cell and Developmental Biology, JT Biohistory Research Hall, Takatsuki, Osaka, 569-1125, Japan.,Department of Biological Sciences, Graduate School of Science, Osaka University, Toyonaka, Japan
| | - Yasuko Akiyama-Oda
- Laboratory of Evolutionary Cell and Developmental Biology, JT Biohistory Research Hall, Takatsuki, Osaka, 569-1125, Japan.,PRESTO, Japan Science and Technology Agency, Kawaguchi, Saitama, 332-0012, Japan.,Department of Microbiology and Infection Control, Faculty of Medicine, Osaka Medical and Pharmaceutical University, Takatsuki, Japan
| | - Hiroki Oda
- Laboratory of Evolutionary Cell and Developmental Biology, JT Biohistory Research Hall, Takatsuki, Osaka, 569-1125, Japan. .,Department of Biological Sciences, Graduate School of Science, Osaka University, Toyonaka, Japan.
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Pechmann M. Embryonic development and secondary axis induction in the Brazilian white knee tarantula Acanthoscurria geniculata, C. L. Koch, 1841 (Araneae; Mygalomorphae; Theraphosidae). Dev Genes Evol 2020; 230:75-94. [PMID: 32076811 PMCID: PMC7128004 DOI: 10.1007/s00427-020-00653-w] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2019] [Accepted: 01/29/2020] [Indexed: 02/07/2023]
Abstract
Tarantulas represent some of the heaviest and most famous spiders. However, there is little information about the embryonic development of these spiders or their relatives (infraorder Mygalomorphae) and time-lapse recording of the embryonic development is entirely missing. I here describe the complete development of the Brazilian white knee tarantula, Acanthoscurria geniculata, in fixed and live embryos. The establishment of the blastoderm, the formation, migration and signalling of the cumulus and the shape changes that occur in the segment addition zone are analysed in detail. In addition, I show that there might be differences in the contraction process of early embryos of different theraphosid spider species. A new embryonic reference transcriptome was generated for this study and was used to clone and analyse the expression of several important developmental genes. Finally, I show that embryos of A. geniculata are amenable to tissue transplantation and bead insertion experiments. Using these functional approaches, I induced axis duplication in embryos via cumulus transplantation and ectopic activation of BMP signalling. Overall, the mygalomorph spider A. geniculata is a useful laboratory system to analyse evolutionary developmental questions, and the availability of such a system will help understanding conserved and divergent aspects of spider/chelicerate development.
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Affiliation(s)
- Matthias Pechmann
- Institute for Zoology, Department for Developmental Biology, Biocenter, University of Cologne, Zuelpicher Str. 47b, 50674, Cologne, Germany.
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Kallal RJ, Hormiga G. Systematics, phylogeny and biogeography of the Australasian leaf-curling orb-weaving spiders (Araneae: Araneidae: Zygiellinae), with a comparative analysis of retreat evolution. Zool J Linn Soc 2018. [DOI: 10.1093/zoolinnean/zly014] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Affiliation(s)
- Robert J Kallal
- The George Washington University, Department of Biological Sciences, Washington, D.C., USA
| | - Gustavo Hormiga
- The George Washington University, Department of Biological Sciences, Washington, D.C., USA
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6
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Pechmann M. Formation of the germ-disc in spider embryos by a condensation-like mechanism. Front Zool 2016; 13:35. [PMID: 27525029 PMCID: PMC4982120 DOI: 10.1186/s12983-016-0166-9] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2016] [Accepted: 07/18/2016] [Indexed: 01/08/2023] Open
Abstract
Background Determination of the embryonic body axes is a crucial developmental process in all animals. The establishment of the embryonic axes of spiders has been best studied in the common-house-spider Parasteatoda tepidariorum. Here, anteroposterior (AP) polarity arises during germ disc formation; the centre of the germ-disc marks the future posterior pole, and the rim of the disc the future anterior pole of the spider embryo. The centre of the germ disc is also needed for the formation of the cumulus, a group of migratory cells needed to establish dorsoventral (DV) polarity. Thus, both body axes depend on proper germ disc formation and patterning. However, these processes have not been fully analysed at the cellular and molecular level. Results Here I present new techniques to stain the cell membranes/outlines in live and fixed spider embryos. I show that the germ-disc is formed from a regular and contiguous blastoderm and that co-ordinated cell shape changes, rather than migration of single cells, are required to drive germ-disc formation in P. tepidariorum embryos. Furthermore, I show that the rate of cell divisions within the embryonic and extra-embryonic region is not involved in the rapid establishment of the germ-disc. Finally, I show that the process of germ-disc formation is dependent on the initiation of zygotic transcription. Conclusions The presented data provide new insights in to the formation of the germ-disc in spider embryos. The establishment of the germ-disc in Parasteatoda embryos is a highly dynamic process that involves wide scale cell-shape changes. While most of the blastodermal cells become cuboidal to form the dense germ-disc, the remaining blastodermal cells stay squamous and develop into huge extra-embryonic, yolk rich cells. In addition, this study shows that the onset of zygotic transcription is needed to establish the germ-disc itself, and that the mid-blastula transition of Parasteatoda tepidariorum embryos is prior to any overt axis establishment. Electronic supplementary material The online version of this article (doi:10.1186/s12983-016-0166-9) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Matthias Pechmann
- University of Cologne, Cologne Biocenter, Zülpicher Str. 47B, 50674 Cologne, Germany
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Edgar A, Bates C, Larkin K, Black S. Gastrulation occurs in multiple phases at two distinct sites in Latrodectus and Cheiracanthium spiders. EvoDevo 2015; 6:33. [PMID: 26500757 PMCID: PMC4618530 DOI: 10.1186/s13227-015-0029-z] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2015] [Accepted: 10/05/2015] [Indexed: 11/28/2022] Open
Abstract
BACKGROUND The longstanding canonical model of spider gastrulation posits that cell internalization occurs only at a unitary central blastopore; and that the cumulus (dorsal organizer) arises from within the early deep layer by cell-cell interaction. Recent work has begun to challenge the canonical model by demonstrating cell internalization at extra-blastoporal sites in two species (Parasteatoda tepidariorum and Zygiella x-notata); and showing in Zygiella that the prospective cumulus internalizes first, before other cells are present in the deep layer. The cell behaviors making up spider gastrulation thus appear to show considerable variation, and a wider sampling of taxa is indicated. RESULTS We evaluated the model in three species from two families by direct observation of living embryos. Movements of individual cells were traced from timelapse recordings and the origin and fate of the cumulus determined by CM-DiI labeling. We show that there are two distinct regions of internalization: most cells enter the deep layer via the central blastopore but many additional cells ingress via an extra-blastoporal ring, either at the periphery of the germ disc (Latrodectus spp.) or nearer the central field (Cheiracanthium mildei). In all species, the cumulus cells internalize first; this is shown by tracing cells in timelapse, histology, and by CM-DiI injection into the deep layer. Injection very early in gastrulation labels only cumulus mesenchyme cells whereas injections at later stages label non-cumulus mesoderm and endoderm. CONCLUSIONS We propose a revised model to accommodate the new data. Our working model has the prospective cumulus cells internalizing first, at the central blastopore. The cumulus cells begin migration before other cells enter the deep layer. This is consistent with early specification of the cumulus and suggests that cell-cell interaction with other deep layer cells is not required for its function. As the cumulus migrates, additional mesendoderm internalizes at two distinct locations: through the central blastopore and at an extra-blastoporal ring. Our work thus demonstrates early, cell-autonomous behavior of the cumulus and variation in subsequent location and timing of cell internalization during gastrulation in spiders.
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Affiliation(s)
- Allison Edgar
- />Kleinholtz Biological Laboratories, Department of Biology, Reed College, 3203 S.E. Woodstock Blvd, Portland, OR 97202 USA
- />Department of Biology, Duke University, Durham, NC 27708 USA
| | - Christine Bates
- />Kleinholtz Biological Laboratories, Department of Biology, Reed College, 3203 S.E. Woodstock Blvd, Portland, OR 97202 USA
- />Department of Internal Medicine, Duke University, Durham, NC 27708 USA
| | - Kay Larkin
- />Kleinholtz Biological Laboratories, Department of Biology, Reed College, 3203 S.E. Woodstock Blvd, Portland, OR 97202 USA
| | - Steven Black
- />Kleinholtz Biological Laboratories, Department of Biology, Reed College, 3203 S.E. Woodstock Blvd, Portland, OR 97202 USA
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8
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Babczyńska A, Binkowski M, Bednarek A, Ogierman S, Cibura D, Migula P, Wilczek G, Szulińska E. X-ray microtomography for imaging of developing spiders inside egg cocoons. ARTHROPOD STRUCTURE & DEVELOPMENT 2014; 43:595-603. [PMID: 25242058 DOI: 10.1016/j.asd.2014.09.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/11/2014] [Revised: 08/07/2014] [Accepted: 09/08/2014] [Indexed: 06/03/2023]
Abstract
Embryogenesis is especially sensitive to external factors. The changes in its course are often used as biomarkers of environmental impact. Since spider embryogenesis takes place inside cocoons, it is crucial to find a reliable tool to analyze this developmental phase with no intrusion into the cocoons. The aim of this study was to verify the efficacy of X-ray microtomography for non-invasive analysis of embryonic morphology and egg quantity in the cocoons of Xerolycosa nemoralis and Agelena labyrinthica from polluted and reference sites. X-ray microtomography slice images as well as 3D images and animations obtained from digital visualization of those slides were used to study the morphology of embryos and egg arrangement in the cocoons. Any disorders in embryogenesis or malformation of embryos in relation to site of origin have not been found, but inside an egg cocoon of X. nemoralis from the polluted site embryos differing form each other by one developmental stage were identified. Egg calculation revealed a K- reproductive strategy of X. nemoralis from polluted sites. Finally, future prospects and benefits, and weaknessess of this method for the study of spider cocoons have presented.
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Affiliation(s)
- Agnieszka Babczyńska
- Department of Animal Physiology and Ecotoxicology, University of Silesia, Bankowa 9, 40-007 Katowice, Poland.
| | - Marcin Binkowski
- X-ray Microtomography Lab, Department of Biomedical Computer Systems, University of Silesia, Będzińska 39, 41-200 Sosnowiec, Poland.
| | - Agata Bednarek
- Department of Animal Physiology and Ecotoxicology, University of Silesia, Bankowa 9, 40-007 Katowice, Poland
| | - Sylwia Ogierman
- X-ray Microtomography Lab, Department of Biomedical Computer Systems, University of Silesia, Będzińska 39, 41-200 Sosnowiec, Poland
| | - Dorota Cibura
- Department of Animal Physiology and Ecotoxicology, University of Silesia, Bankowa 9, 40-007 Katowice, Poland
| | - Paweł Migula
- Department of Animal Physiology and Ecotoxicology, University of Silesia, Bankowa 9, 40-007 Katowice, Poland
| | - Grażyna Wilczek
- Department of Animal Physiology and Ecotoxicology, University of Silesia, Bankowa 9, 40-007 Katowice, Poland
| | - Elżbieta Szulińska
- Department of Animal Physiology and Ecotoxicology, University of Silesia, Bankowa 9, 40-007 Katowice, Poland
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9
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Expression of the decapentaplegic ortholog in embryos of the onychophoran Euperipatoides rowelli. Gene Expr Patterns 2013; 13:384-94. [DOI: 10.1016/j.gep.2013.07.004] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2013] [Revised: 07/07/2013] [Accepted: 07/10/2013] [Indexed: 12/21/2022]
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10
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Mittmann B, Wolff C. Embryonic development and staging of the cobweb spider Parasteatoda tepidariorum C. L. Koch, 1841 (syn.: Achaearanea tepidariorum; Araneomorphae; Theridiidae). Dev Genes Evol 2012; 222:189-216. [DOI: 10.1007/s00427-012-0401-0] [Citation(s) in RCA: 68] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2012] [Accepted: 04/18/2012] [Indexed: 12/22/2022]
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11
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Hunnekuhl VS, Wolff C. Reconstruction of cell lineage and spatiotemporal pattern formation of the mesoderm in the amphipod crustacean Orchestia cavimana. Dev Dyn 2012; 241:697-717. [PMID: 22374787 DOI: 10.1002/dvdy.23758] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/29/2012] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Cell lineage studies in amphipods have revealed an early restriction of blastomere fate. The mesendodermal cell lineage is specified with the third cleavage of the egg. We took advantage of this stereotyped mode of development by fluorescently labeling the mesodermal precursors in embryos of Orchestia cavimana and followed the morphogenesis of the mesodermal cell layer through embryonic development. RESULTS The mesoderm of the trunk segments is formed by a very regular and stereotypic cell division pattern of the mesoteloblasts and their segmental daughters. The head mesoderm in contrast is generated by cell movements and divisions out of a mesendodermal cell mass. Our reconstructions reveal the presence of three different domains within the trunk mesoderm of the later embryo. We distinguish a cell group median to the limbs, a major central population from which the limb mesoderm arises and a dorsolateral branch of mesodermal cells. CONCLUSIONS Our detailed description of mesodermal development relates different precursor cell groups to distinct muscle groups of the embryo. A dorsoventral subdivision of mesoderm is prepatterned within the longitudinal mesodermal columns of the germ-band stage. This makes amphipods excellent crustacean models for studying mesodermal differentiation on a cellular and molecular level.
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Affiliation(s)
- Vera S Hunnekuhl
- Laboratory for Evolution and Development, Department of Zoology, Cambridge, UK
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12
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Brena C, Akam M. The embryonic development of the centipede Strigamia maritima. Dev Biol 2011; 363:290-307. [PMID: 22138381 DOI: 10.1016/j.ydbio.2011.11.006] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2011] [Revised: 10/18/2011] [Accepted: 11/10/2011] [Indexed: 01/11/2023]
Abstract
The geophilomorph centipede Strigamia maritima is an emerging model for studies of development and evolution among the myriapods. A draft genome sequence has recently been completed, making it also an important reference for comparative genomics, and for studies of myriapod physiology more generally. Here we present the first detailed description of myriapod development using modern techniques. We describe a timeline for embryonic development, with a detailed staging system based on photographs of live eggs and fixed embryos. We show that the early, cleavage and nuclear migration, stages of development are remarkably prolonged, accounting for nearly half of the total developmental period (approx 22 of 48 days at 13 °C). Towards the end of this period, cleavage cells migrate to the egg periphery to generate a uniform blastoderm. Asymmetry quickly becomes apparent as cells in the anterior half of the egg condense ventrally to form the presumptive head. Five anterior segments, the mandibular to the first leg-bearing segment (1st LBS) become clearly visible through the chorion almost simultaneously. Then, after a short pause, the next 35 leg-bearing segments appear at a uniform rate of 1 segment every 3.2 h (at 13 °C). Segment addition then slows to a halt with 40-45 LBS, shortly before the dramatic movements of germ band flexure, when the left and right halves of the embryo separate and the embryo folds deeply into the yolk. After flexure, segment morphogenesis and organogenesis proceed for a further 10 days, before the egg hatches. The last few leg-bearing segments are added during this period, much more slowly, at a rate of 1-2 segments/day. The last leg-bearing segment is fully defined only after apolysis of the embryonic cuticle, so that at hatching the embryo displays the final adult number of leg-bearing segments (typically 47-49 in our population).
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Affiliation(s)
- Carlo Brena
- Laboratory for Development and Evolution, Department of Zoology, University of Cambridge, UK.
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13
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Wolff C, Hilbrant M. The embryonic development of the central American wandering spider Cupiennius salei. Front Zool 2011; 8:15. [PMID: 21672209 PMCID: PMC3141654 DOI: 10.1186/1742-9994-8-15] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2010] [Accepted: 06/14/2011] [Indexed: 12/04/2022] Open
Abstract
Background The spider Cupiennius salei (Keyserling 1877) has become an important study organism in evolutionary and developmental biology. However, the available staging system for its embryonic development is difficult to apply to modern studies, with strong bias towards the earliest developmental stages. Furthermore, important embryonic events are poorly understood. We address these problems, providing a new description of the embryonic development of C. salei. The paper also discusses various observations that will improve our understanding of spider development. Results Conspicuous developmental events were used to define numbered stages 1 to 21. Stages 1 to 9 follow the existing staging system for the spider Achaearanea tepidariorum, and stages 10 to 21 provide a high-resolution description of later development. Live-embryo imaging shows cell movements during the earliest formation of embryonic tissue in C. salei. The imaging procedure also elucidates the encircling border between the cell-dense embryo hemisphere and the hemisphere with much lower cell density (a structure termed 'equator' in earlier studies). This border results from subsurface migration of primordial mesendodermal cells from their invagination site at the blastopore. Furthermore, our detailed successive sequence shows: 1) early differentiation of the precheliceral neuroectoderm; 2) the morphogenetic process of inversion and 3) initial invaginations of the opisthosomal epithelium for the respiratory system. Conclusions Our improved staging system of development in C. salei development should be of considerable value to future comparative studies of animal development. A dense germ disc is not evident during development in C. salei, but we show that the gastrulation process is similar to that in spider species that do have a dense germ disc. In the opisthosoma, the order of appearance of precursor epithelial invaginations provides evidence for the non-homology of the tracheal and book lung respiratory systems.
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Affiliation(s)
- Carsten Wolff
- Humboldt-Universität zu Berlin Institut für Biologie/Vergleichende Zoologie Philippstraße 13, 10115 Berlin, Germany
| | - Maarten Hilbrant
- Universität zu Köln Institut für Genetik, Zülpicher Straße 47a, 50674 Köln, Germany.,Oxford Brookes University Headington Campus Gipsy Lane, Oxford OX3 0BP, UK
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14
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Mayer G, Whitington PM. Velvet worm development links myriapods with chelicerates. Proc Biol Sci 2009; 276:3571-9. [PMID: 19640885 PMCID: PMC2817307 DOI: 10.1098/rspb.2009.0950] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2009] [Accepted: 07/06/2009] [Indexed: 12/21/2022] Open
Abstract
Despite the advent of modern molecular and computational methods, the phylogeny of the four major arthropod groups (Chelicerata, Myriapoda, Crustacea and Hexapoda, including the insects) remains enigmatic. One particular challenge is the position of myriapods as either the closest relatives to chelicerates (Paradoxopoda/Myriochelata hypothesis), or to crustaceans and hexapods (Mandibulata hypothesis). While neither hypothesis receives conclusive support from molecular analyses, most morphological studies favour the Mandibulata concept, with the mandible being the most prominent feature of this group. Although no morphological evidence was initially available to support the Paradoxopoda hypothesis, a putative synapomorphy of chelicerates and myriapods has recently been put forward based on studies of neurogenesis. However, this and other morphological characters remain of limited use for phylogenetic systematics owing to the lack of data from an appropriate outgroup. Here, we show that several embryonic characters are synapomorphies uniting the chelicerates and myriapods, as revealed by an outgroup comparison with the Onychophora or velvet worms. Our findings, thus provide, to our knowledge, first morphological/embryological support for the monophyly of the Paradoxopoda and suggest that the mandible might have evolved twice within the arthropods.
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Affiliation(s)
- Georg Mayer
- Department of Anatomy and Cell Biology, University of Melbourne, Melbourne, Victoria 3010, Australia.
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15
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Liu Y, Maas A, Waloszek D. Early development of the anterior body region of the grey widow spider Latrodectus geometricus Koch, 1841 (Theridiidae, Araneae). ARTHROPOD STRUCTURE & DEVELOPMENT 2009; 38:401-16. [PMID: 19374954 DOI: 10.1016/j.asd.2009.04.001] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/17/2008] [Revised: 03/26/2009] [Accepted: 04/01/2009] [Indexed: 05/14/2023]
Abstract
We document the early morphogenesis of Latrodectus geometricus, particularly of the anterior body region. Significant changes in the development of the external prosomal structures revealed with scanning electron microscopy (SEM) images include: (1) reorganisation of each pre-cheliceral lobe by subdivision and internalisation of its central area; (2) shortening of the ventro-median bridge connecting the pre-cheliceral lobes and its eventual disappearance; (3) appearance and expansion of a prospective mouth region between the pre-cheliceral lobes with a recessed median area surrounded by lip-like borders, the anterior lip-part developing into the hypostome; (4) reduction of the mouth region to an area around the hypostome and the lip-like latero-posterior border of the mouth opening; (5) change of the position of the mouth region from anterior to the insertions of the chelicerae to posterior to them; (6) eventual shortening of the mouth opening to a slit overhung by the hypostome; (7) origination of the prosomal shield from the anterior margin of the pre-cheliceral lobes and the tergal portions of the four posterior-most prosomal segments; and (8) expansion of a 'ventral sulcus' from the cheliceral to the fifth opisthosomal segment separating the sides of these segments. Embryonic features are compared across the Chelicerata and discussed briefly in a phylogenetic context.
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Affiliation(s)
- Yu Liu
- University of Ulm, Germany.
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