1
|
Schindler-Johnson M, Petridou NI. Collective effects of cell cleavage dynamics. Front Cell Dev Biol 2024; 12:1358971. [PMID: 38559810 PMCID: PMC10978805 DOI: 10.3389/fcell.2024.1358971] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2023] [Accepted: 03/05/2024] [Indexed: 04/04/2024] Open
Abstract
A conserved process of early embryonic development in metazoans is the reductive cell divisions following oocyte fertilization, termed cell cleavages. Cell cleavage cycles usually start synchronously, lengthen differentially between the embryonic cells becoming asynchronous, and cease before major morphogenetic events, such as germ layer formation and gastrulation. Despite exhibiting species-specific characteristics, the regulation of cell cleavage dynamics comes down to common controllers acting mostly at the single cell/nucleus level, such as nucleus-to-cytoplasmic ratio and zygotic genome activation. Remarkably, recent work has linked cell cleavage dynamics to the emergence of collective behavior during embryogenesis, including pattern formation and changes in embryo-scale mechanics, raising the question how single-cell controllers coordinate embryo-scale processes. In this review, we summarize studies across species where an association between cell cleavages and collective behavior was made, discuss the underlying mechanisms, and propose that cell-to-cell variability in cell cleavage dynamics can serve as a mechanism of long-range coordination in developing embryos.
Collapse
Affiliation(s)
- Magdalena Schindler-Johnson
- Developmental Biology Unit, European Molecular Biology Laboratory, Heidelberg, Germany
- Faculty of Biosciences, Heidelberg University, Heidelberg, Germany
| | - Nicoletta I. Petridou
- Developmental Biology Unit, European Molecular Biology Laboratory, Heidelberg, Germany
| |
Collapse
|
2
|
McCartney B, Dudin O. Cellularization across eukaryotes: Conserved mechanisms and novel strategies. Curr Opin Cell Biol 2023; 80:102157. [PMID: 36857882 DOI: 10.1016/j.ceb.2023.102157] [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: 07/15/2022] [Revised: 01/27/2023] [Accepted: 01/31/2023] [Indexed: 03/02/2023]
Abstract
Many eukaryotes form multinucleated cells during their development. Some cells persist as such during their lifetime, others choose to cleave each nucleus individually using a specialized cytokinetic process known as cellularization. What is cellularization and how is it achieved across the eukaryotic tree of life? Are there common pathways among all species supporting a shared ancestry, or are there key differences, suggesting independent evolutionary paths? In this review, we discuss common strategies and key mechanistic differences in how cellularization is executed across vastly divergent eukaryotic species. We present a number of novel methods and non-model organisms that may provide important insight into the evolutionary origins of cellularization.
Collapse
Affiliation(s)
- Brooke McCartney
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, PA 15213, USA.
| | - Omaya Dudin
- Swiss Institute for Experimental Cancer Research, School of Life Sciences, Swiss Federal Institute of Technology (EPFL), Lausanne, Switzerland.
| |
Collapse
|
3
|
Sokac AM, Biel N, De Renzis S. Membrane-actin interactions in morphogenesis: Lessons learned from Drosophila cellularization. Semin Cell Dev Biol 2023; 133:107-122. [PMID: 35396167 PMCID: PMC9532467 DOI: 10.1016/j.semcdb.2022.03.028] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2022] [Revised: 03/18/2022] [Accepted: 03/21/2022] [Indexed: 01/12/2023]
Abstract
During morphogenesis, changes in the shapes of individual cells are harnessed to mold an entire tissue. These changes in cell shapes require the coupled remodeling of the plasma membrane and underlying actin cytoskeleton. In this review, we highlight cellularization of the Drosophila embryo as a model system to uncover principles of how membrane and actin dynamics are co-regulated in space and time to drive morphogenesis.
Collapse
Affiliation(s)
- Anna Marie Sokac
- Department of Cell and Developmental Biology, University of Illinois at Urbana Champaign, Urbana, IL 61801, USA; Graduate Program in Integrative and Molecular Biomedical Sciences, Baylor College of Medicine, Houston, TX 77030, USA.
| | - Natalie Biel
- Department of Cell and Developmental Biology, University of Illinois at Urbana Champaign, Urbana, IL 61801, USA; Graduate Program in Integrative and Molecular Biomedical Sciences, Baylor College of Medicine, Houston, TX 77030, USA
| | - Stefano De Renzis
- European Molecular Biology Laboratory Heidelberg, 69117 Heidelberg, Germany
| |
Collapse
|
4
|
Neves JH, Rezende-Teixeira P, Palomino NB, Machado-Santelli GM. Molecular and morphological approach to study the innexin gap junctions in Rhynchosciara americana. Open Biol 2021; 11:210224. [PMID: 34753320 PMCID: PMC8580445 DOI: 10.1098/rsob.210224] [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] [Indexed: 01/04/2023] Open
Abstract
Gap junctions mediate communication between adjacent cells and are fundamental to the development and homeostasis in multicellular organisms. In invertebrates, gap junctions are formed by transmembrane proteins called innexins. Gap junctions allow the passage of small molecules through an intercellular channel, between a cell and another adjacent cell. The dipteran Rhynchosciara americana has contributed to studying the biology of invertebrates and the study of the interaction and regulation of genes during biological development. Therefore, this paper aimed to study the R. americana innexin-2 by molecular characterization, analysis of the expression profile and cellular localization. The molecular characterization results confirm that the message is from a gap junction protein and analysis of the expression and cellular localization profile shows that innexin-2 can participate in many physiological processes during the development of R. americana.
Collapse
Affiliation(s)
- Jorge Henrique Neves
- Institute of Biomedical Sciences, University of São Paulo, Avenida Professor Lineu Prestes, 1524 – sala 307, São Paulo, SP, Brazil
| | - Paula Rezende-Teixeira
- Institute of Biomedical Sciences, University of São Paulo, Avenida Professor Lineu Prestes, 1524 – sala 307, São Paulo, SP, Brazil
| | - Natalia Bazan Palomino
- Institute of Biomedical Sciences, University of São Paulo, Avenida Professor Lineu Prestes, 1524 – sala 307, São Paulo, SP, Brazil
| | - Glaucia Maria Machado-Santelli
- Institute of Biomedical Sciences, University of São Paulo, Avenida Professor Lineu Prestes, 1524 – sala 307, São Paulo, SP, Brazil
| |
Collapse
|
5
|
Lemke S, Kale G, Urbansky S. Comparing gastrulation in flies: Links between cell biology and the evolution of embryonic morphogenesis. Mech Dev 2020. [DOI: 10.1016/j.mod.2020.103648] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
|
6
|
Quan H, Arsala D, Lynch JA. Transcriptomic and functional analysis of the oosome, a unique form of germ plasm in the wasp Nasonia vitripennis. BMC Biol 2019; 17:78. [PMID: 31601213 PMCID: PMC6785909 DOI: 10.1186/s12915-019-0696-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2019] [Accepted: 08/30/2019] [Indexed: 11/20/2022] Open
Abstract
BACKGROUND The oosome is the germline determinant in the wasp Nasonia vitripennis and is homologous to the polar granules of Drosophila. Despite a common evolutionary origin and developmental role, the oosome is morphologically quite distinct from polar granules. It is a solid sphere that migrates within the cytoplasm before budding out and forming pole cells. RESULTS To gain an understanding of both the molecular basis of oosome development and the conserved essential features of germ plasm, we quantified and compared transcript levels between embryo fragments that contained the oosome and those that did not. The identity of the differentially localized transcripts indicated that Nasonia uses a distinct set of molecules to carry out conserved germ plasm functions. In addition, functional testing of a sample of localized transcripts revealed potentially novel mechanisms of ribonucleoprotein assembly and pole cell cellularization in the wasp. CONCLUSIONS Our results demonstrate that the composition of germ plasm varies significantly within Holometabola, as very few mRNAs share localization to the oosome and polar granules. Some of this variability appears to be related to the unique properties of the oosome relative to the polar granules in Drosophila, and some may be related to differences in pole formation between species. This work will serve as the basis for further investigation into the patterns of germline determinant evolution among insects, the molecular basis of the unique properties of the oosome, and the incorporation of novel components into developmental networks.
Collapse
Affiliation(s)
- Honghu Quan
- Department of Pathology and Department of Cell and Molecular Biology, St. Jude Children’s Research Hospital, Memphis, TN 38105 USA
| | - Deanna Arsala
- Department of Biological Sciences, University of Illinois at Chicago, Chicago, IL 60607 USA
| | - Jeremy A. Lynch
- Department of Biological Sciences, University of Illinois at Chicago, Chicago, IL 60607 USA
| |
Collapse
|
7
|
Benton MA, Frey N, Nunes da Fonseca R, von Levetzow C, Stappert D, Hakeemi MS, Conrads KH, Pechmann M, Panfilio KA, Lynch JA, Roth S. Fog signaling has diverse roles in epithelial morphogenesis in insects. eLife 2019; 8:47346. [PMID: 31573513 PMCID: PMC6794076 DOI: 10.7554/elife.47346] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2019] [Accepted: 09/30/2019] [Indexed: 12/14/2022] Open
Abstract
The Drosophila Fog pathway represents one of the best-understood signaling cascades controlling epithelial morphogenesis. During gastrulation, Fog induces apical cell constrictions that drive the invagination of mesoderm and posterior gut primordia. The cellular mechanisms underlying primordia internalization vary greatly among insects and recent work has suggested that Fog signaling is specific to the fast mode of gastrulation found in some flies. On the contrary, here we show in the beetle Tribolium, whose development is broadly representative for insects, that Fog has multiple morphogenetic functions. It modulates mesoderm internalization and controls a massive posterior infolding involved in gut and extraembryonic development. In addition, Fog signaling affects blastoderm cellularization, primordial germ cell positioning, and cuboidal-to-squamous cell shape transitions in the extraembryonic serosa. Comparative analyses with two other distantly related insect species reveals that Fog's role during cellularization is widely conserved and therefore might represent the ancestral function of the pathway.
Collapse
Affiliation(s)
- Matthew Alan Benton
- Institute for Zoology/Developmental Biology, Biocenter, University of Cologne, Köln, Germany.,Department of Zoology, University of Cambridge, Cambridge, United Kingdom
| | - Nadine Frey
- Institute for Zoology/Developmental Biology, Biocenter, University of Cologne, Köln, Germany
| | | | - Cornelia von Levetzow
- Institute for Zoology/Developmental Biology, Biocenter, University of Cologne, Köln, Germany
| | - Dominik Stappert
- Institute for Zoology/Developmental Biology, Biocenter, University of Cologne, Köln, Germany
| | - Muhammad Salim Hakeemi
- Institute for Zoology/Developmental Biology, Biocenter, University of Cologne, Köln, Germany
| | - Kai H Conrads
- Institute for Zoology/Developmental Biology, Biocenter, University of Cologne, Köln, Germany
| | - Matthias Pechmann
- Institute for Zoology/Developmental Biology, Biocenter, University of Cologne, Köln, Germany
| | - Kristen A Panfilio
- Institute for Zoology/Developmental Biology, Biocenter, University of Cologne, Köln, Germany.,School of Life Sciences, University of Warwick, Coventry, United Kingdom
| | - Jeremy A Lynch
- Department of Biological Sciences, University of Illinois, Chicago, United States
| | - Siegfried Roth
- Institute for Zoology/Developmental Biology, Biocenter, University of Cologne, Köln, Germany
| |
Collapse
|
8
|
Güiza J, Barría I, Sáez JC, Vega JL. Innexins: Expression, Regulation, and Functions. Front Physiol 2018; 9:1414. [PMID: 30364195 PMCID: PMC6193117 DOI: 10.3389/fphys.2018.01414] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2018] [Accepted: 09/18/2018] [Indexed: 01/02/2023] Open
Abstract
The innexin (Inx) proteins form gap junction channels and non-junctional channels (named hemichannels) in invertebrates. These channels participate in cellular communication playing a relevant role in several physiological processes. Pioneer studies conducted mainly in worms and flies have shown that innexins participate in embryo development and behavior. However, recent studies have elucidated new functions of innexins in Arthropoda, Nematoda, Annelida, and Cnidaria, such as immune response, and apoptosis. This review describes emerging data of possible new roles of innexins and summarizes the data available to date.
Collapse
Affiliation(s)
- Juan Güiza
- Laboratorio de Fisiología Experimental, Instituto Antofagasta, Universidad de Antofagasta, Antofagasta, Chile
| | - Iván Barría
- Laboratorio de Fisiología Experimental, Instituto Antofagasta, Universidad de Antofagasta, Antofagasta, Chile
| | - Juan C Sáez
- Departamento de Fisiología, Pontificia Universidad Católica de Chile, Santiago, Chile.,Instituto de Neurociencias, Centro Interdisciplinario de Neurociencias de Valparaíso, Universidad de Valparaíso, Valparaíso, Chile
| | - José L Vega
- Laboratorio de Fisiología Experimental, Instituto Antofagasta, Universidad de Antofagasta, Antofagasta, Chile
| |
Collapse
|
9
|
van Drongelen R, Vazquez-Faci T, Huijben TAPM, van der Zee M, Idema T. Mechanics of epithelial tissue formation. J Theor Biol 2018; 454:182-189. [PMID: 29883740 DOI: 10.1016/j.jtbi.2018.06.002] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2017] [Revised: 05/31/2018] [Accepted: 06/03/2018] [Indexed: 01/06/2023]
Abstract
A key process in the life of any multicellular organism is its development from a single egg into a full grown adult. The first step in this process often consists of forming a tissue layer out of randomly placed cells on the surface of the egg. We present a model for generating such a tissue, based on mechanical interactions between the cells, and find that the resulting cellular pattern corresponds to the Voronoi tessellation of the nuclei of the cells. Experimentally, we obtain the same result in both fruit flies and flour beetles, with a distribution of cell shapes that matches that of the model, without any adjustable parameters. Finally, we show that this pattern is broken when the cells grow at different rates.
Collapse
Affiliation(s)
- Ruben van Drongelen
- Department of Bionanoscience, Kavli Institute of Nanoscience, Delft University of Technology, Van der Maasweg 9, 2629 HZ Delft, The Netherlands
| | - Tania Vazquez-Faci
- Department of Bionanoscience, Kavli Institute of Nanoscience, Delft University of Technology, Van der Maasweg 9, 2629 HZ Delft, The Netherlands; Institute of Biology, Leiden University, Sylviusweg 72, Leiden 2333 BE, The Netherlands
| | - Teun A P M Huijben
- Department of Bionanoscience, Kavli Institute of Nanoscience, Delft University of Technology, Van der Maasweg 9, 2629 HZ Delft, The Netherlands
| | - Maurijn van der Zee
- Institute of Biology, Leiden University, Sylviusweg 72, Leiden 2333 BE, The Netherlands
| | - Timon Idema
- Department of Bionanoscience, Kavli Institute of Nanoscience, Delft University of Technology, Van der Maasweg 9, 2629 HZ Delft, The Netherlands.
| |
Collapse
|
10
|
Benton MA. A revised understanding of Tribolium morphogenesis further reconciles short and long germ development. PLoS Biol 2018; 16:e2005093. [PMID: 29969459 PMCID: PMC6047830 DOI: 10.1371/journal.pbio.2005093] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2017] [Revised: 07/16/2018] [Accepted: 06/15/2018] [Indexed: 11/19/2022] Open
Abstract
In Drosophila melanogaster, the germband forms directly on the egg surface and solely consists of embryonic tissue. In contrast, most insect embryos undergo a complicated set of tissue rearrangements to generate a condensed, multilayered germband. The ventral side of the germband is embryonic, while the dorsal side is thought to be an extraembryonic tissue called the amnion. While this tissue organisation has been accepted for decades and has been widely reported in insects, its accuracy has not been directly tested in any species. Using live cell tracking and differential cell labelling in the short germ beetle Tribolium castaneum, I show that most of the cells previously thought to be amnion actually give rise to large parts of the embryo. This process occurs via the dorsal-to-ventral flow of cells and contributes to germband extension (GBE). In addition, I show that true 'amnion' cells in Tribolium originate from a small region of the blastoderm. Together, my findings show that development in the short germ embryos of Tribolium and the long germ embryos of Drosophila is more similar than previously proposed. Dorsal-to-ventral cell flow also occurs in Drosophila during GBE, and I argue that the flow is driven by a conserved set of underlying morphogenetic events in both species. Furthermore, the revised Tribolium fate map that I present is far more similar to that of Drosophila than the classic Tribolium fate map. Lastly, my findings show that there is no qualitative difference between the tissue structure of the cellularised blastoderm and the short/intermediate germ germband. As such, the same tissue patterning mechanisms could function continuously throughout the cellularised blastoderm and germband stages, and easily shift between them over evolutionary time.
Collapse
|
11
|
Strobl F, Klees S, Stelzer EHK. Light Sheet-based Fluorescence Microscopy of Living or Fixed and Stained Tribolium castaneum Embryos. J Vis Exp 2017. [PMID: 28518097 DOI: 10.3791/55629] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
The red flour beetle Tribolium castaneum has become an important insect model organism in developmental genetics and evolutionary developmental biology. The observation of Tribolium embryos with light sheet-based fluorescence microscopy has multiple advantages over conventional widefield and confocal fluorescence microscopy. Due to the unique properties of a light sheet-based microscope, three dimensional images of living specimens can be recorded with high signal-to-noise ratios and significantly reduced photo-bleaching as well as photo-toxicity along multiple directions over periods that last several days. With more than four years of methodological development and a continuous increase of data, the time seems appropriate to establish standard operating procedures for the usage of light sheet technology in the Tribolium community as well as in the insect community at large. This protocol describes three mounting techniques suitable for different purposes, presents two novel custom-made transgenic Tribolium lines appropriate for long-term live imaging, suggests five fluorescent dyes to label intracellular structures of fixed embryos and provides information on data post-processing for the timely evaluation of the recorded data. Representative results concentrate on long-term live imaging, optical sectioning and the observation of the same embryo along multiple directions. The respective datasets are provided as a downloadable resource. Finally, the protocol discusses quality controls for live imaging assays, current limitations and the applicability of the outlined procedures to other insect species. This protocol is primarily intended for developmental biologists who seek imaging solutions that outperform standard laboratory equipment. It promotes the continuous attempt to close the gap between the technically orientated laboratories/communities, which develop and refine microscopy methodologically, and the life science laboratories/communities, which require 'plug-and-play' solutions to technical challenges. Furthermore, it supports an axiomatic approach that moves the biological questions into the center of attention.
Collapse
Affiliation(s)
- Frederic Strobl
- Physical Biology, Buchmann Institute for Molecular Life Sciences (BMLS); Cluster of Excellence Frankfurt, Macromolecular Complexes; Goethe-Universität Frankfurt am Main - Campus Riedberg
| | - Selina Klees
- Physical Biology, Buchmann Institute for Molecular Life Sciences (BMLS); Cluster of Excellence Frankfurt, Macromolecular Complexes; Goethe-Universität Frankfurt am Main - Campus Riedberg
| | - Ernst H K Stelzer
- Physical Biology, Buchmann Institute for Molecular Life Sciences (BMLS); Cluster of Excellence Frankfurt, Macromolecular Complexes; Goethe-Universität Frankfurt am Main - Campus Riedberg;
| |
Collapse
|
12
|
Strobl F, Stelzer EH. Long-term fluorescence live imaging of Tribolium castaneum embryos: principles, resources, scientific challenges and the comparative approach. CURRENT OPINION IN INSECT SCIENCE 2016; 18:17-26. [PMID: 27939706 DOI: 10.1016/j.cois.2016.08.002] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/16/2016] [Accepted: 08/07/2016] [Indexed: 06/06/2023]
Abstract
Light sheet-based fluorescence microscopy became an important tool in insect developmental biology due to its high acquisition speed, low photo-bleaching rate and the high survival probability of the specimens. Initially applied to document the embryogenesis of Drosophila melanogaster, it is now used to investigate the embryonic morphogenesis of emerging model organisms such as the red flour beetle Tribolium castaneum. Here, we discuss the principles of light sheet-based fluorescence microscopy and outline Tribolium as a model organism for developmental biology. We summarize labeling options and present two custom-made transgenic lines suitable for live imaging. Finally, we highlight studies on Tribolium that address scientific questions with fluorescence live imaging and discuss the comparative approach to investigate insect morphogenesis in an evolutionary context.
Collapse
Affiliation(s)
- Frederic Strobl
- Physical Biology/Physikalische Biologie (IZN, FB 15), Buchmann Institute for Molecular Life Sciences (BMLS), Cluster of Excellence Frankfurt - Macromolecular Complexes (CEF-MC), Goethe Universität - Frankfurt am Main (Campus Riedberg), Max-von-Laue-Straße 15, D-60348 Frankfurt am Main, Germany
| | - Ernst Hk Stelzer
- Physical Biology/Physikalische Biologie (IZN, FB 15), Buchmann Institute for Molecular Life Sciences (BMLS), Cluster of Excellence Frankfurt - Macromolecular Complexes (CEF-MC), Goethe Universität - Frankfurt am Main (Campus Riedberg), Max-von-Laue-Straße 15, D-60348 Frankfurt am Main, Germany.
| |
Collapse
|
13
|
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.
Collapse
Affiliation(s)
- Matthias Pechmann
- University of Cologne, Cologne Biocenter, Zülpicher Str. 47B, 50674 Cologne, Germany
| |
Collapse
|
14
|
Schmidt-Ott U, Lynch JA. Emerging developmental genetic model systems in holometabolous insects. Curr Opin Genet Dev 2016; 39:116-128. [PMID: 27399647 DOI: 10.1016/j.gde.2016.06.004] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2016] [Revised: 05/25/2016] [Accepted: 06/08/2016] [Indexed: 01/08/2023]
Abstract
The number of insect species that are amenable to functional genetic studies is growing rapidly and provides many new research opportunities in developmental and evolutionary biology. The holometabolous insects represent a disproportionate percentage of animal diversity and are thus well positioned to provide model species for a wide variety of developmental processes. Here we discuss emerging holometabolous models, and review some recent breakthroughs. For example, flies and midges were found to use structurally unrelated long-range pattern organizers, butterflies and moths revealed extensive pattern formation during oogenesis, new imaging possibilities in the flour beetle Tribolium castaneum showed how embryos break free of their extraembryonic membranes, and the complex genetics governing interspecies difference in head shape were revealed in Nasonia wasps.
Collapse
Affiliation(s)
- Urs Schmidt-Ott
- Department of Organismal Biology and Anatomy, University of Chicago, United States.
| | - Jeremy A Lynch
- Department of Biological Sciences, University of Illinois at Chicago, United States.
| |
Collapse
|
15
|
Toll Genes Have an Ancestral Role in Axis Elongation. Curr Biol 2016; 26:1609-1615. [DOI: 10.1016/j.cub.2016.04.055] [Citation(s) in RCA: 69] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2016] [Revised: 04/06/2016] [Accepted: 04/20/2016] [Indexed: 12/17/2022]
|
16
|
Oshima A, Matsuzawa T, Murata K, Tani K, Fujiyoshi Y. Hexadecameric structure of an invertebrate gap junction channel. J Mol Biol 2016; 428:1227-1236. [DOI: 10.1016/j.jmb.2016.02.011] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2015] [Revised: 02/05/2016] [Accepted: 02/08/2016] [Indexed: 12/12/2022]
|