1
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Sarkar SR, Dubey VK, Jahagirdar A, Lakshmanan V, Haroon MM, Sowndarya S, Sowdhamini R, Palakodeti D. DDX24 is required for muscle fiber organization and the suppression of wound-induced Wnt activity necessary for pole re-establishment during planarian regeneration. Dev Biol 2022; 488:11-29. [PMID: 35523320 DOI: 10.1016/j.ydbio.2022.04.011] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2022] [Revised: 04/06/2022] [Accepted: 04/28/2022] [Indexed: 12/14/2022]
Abstract
Planarians have a remarkable ability to undergo whole-body regeneration. Successful regeneration outcome is determined by processes like polarity establishment at the wound site, which is followed by pole (organizer) specification. Interestingly, these determinants are almost exclusively expressed by muscles in these animals. However, the molecular toolkit that enables the functional versatility of planarian muscles remains poorly understood. Here we report that SMED_DDX24, a D-E-A-D Box RNA helicase, is necessary for planarian survival and regeneration. We found that DDX24 is enriched in muscles and its knockdown disrupts muscle fiber organization. This leads to defective pole specification, which in turn results in misregulation of many positional control genes specifically during regeneration. ddx24 RNAi also upregulates wound-induced Wnt signalling. Suppressing this ectopic Wnt activity rescues the knockdown phenotype by enabling better anterior pole regeneration. To summarize, our work highlights the role of an RNA helicase in muscle fiber organization, and modulating amputation-induced wnt levels, both of which seem critical for pole re-organization, thereby regulating whole-body regeneration.
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Affiliation(s)
- Souradeep R Sarkar
- National Centre for Biological Sciences (NCBS), Tata Institute of Fundamental Research (TIFR), Bengaluru, 560065, India; Integrative Chemical Biology (ICB), Institute for Stem Cell Science and Regenerative Medicine (inStem), Bengaluru, 560065, India
| | - Vinay Kumar Dubey
- Integrative Chemical Biology (ICB), Institute for Stem Cell Science and Regenerative Medicine (inStem), Bengaluru, 560065, India; Manipal Academy of Higher Education, Manipal, 576104, India
| | - Anusha Jahagirdar
- Integrative Chemical Biology (ICB), Institute for Stem Cell Science and Regenerative Medicine (inStem), Bengaluru, 560065, India
| | - Vairavan Lakshmanan
- Integrative Chemical Biology (ICB), Institute for Stem Cell Science and Regenerative Medicine (inStem), Bengaluru, 560065, India
| | - Mohamed Mohamed Haroon
- Integrative Chemical Biology (ICB), Institute for Stem Cell Science and Regenerative Medicine (inStem), Bengaluru, 560065, India; SASTRA University, Thanjavur, 613401, India
| | - Sai Sowndarya
- Integrative Chemical Biology (ICB), Institute for Stem Cell Science and Regenerative Medicine (inStem), Bengaluru, 560065, India
| | - Ramanathan Sowdhamini
- National Centre for Biological Sciences (NCBS), Tata Institute of Fundamental Research (TIFR), Bengaluru, 560065, India
| | - Dasaradhi Palakodeti
- Integrative Chemical Biology (ICB), Institute for Stem Cell Science and Regenerative Medicine (inStem), Bengaluru, 560065, India.
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2
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Bonar NA, Gittin DI, Petersen CP. Src acts with WNT/FGFRL signaling to pattern the planarian anteroposterior axis. Development 2022; 149:274880. [PMID: 35297964 PMCID: PMC8995084 DOI: 10.1242/dev.200125] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2021] [Accepted: 03/03/2022] [Indexed: 01/18/2023]
Abstract
Tissue identity determination is crucial for regeneration, and the planarian anteroposterior (AP) axis uses positional control genes expressed from body wall muscle to determine body regionalization. Canonical Wnt signaling establishes anterior versus posterior pole identities through notum and wnt1 signaling, and two Wnt/FGFRL signaling pathways control head and trunk domains, but their downstream signaling mechanisms are not fully understood. Here, we identify a planarian Src homolog that restricts head and trunk identities to anterior positions. src-1(RNAi) animals formed enlarged brains and ectopic eyes and also duplicated trunk tissue, similar to a combination of Wnt/FGFRL RNAi phenotypes. src-1 was required for establishing territories of positional control gene expression in Schmidtea mediterranea, indicating that it acts at an upstream step in patterning the AP axis. Double RNAi experiments and eye regeneration assays suggest src-1 can act in parallel to at least some Wnt and FGFRL factors. Co-inhibition of src-1 with other posterior-promoting factors led to dramatic patterning changes and a reprogramming of Wnt/FGFRLs into controlling new positional outputs. These results identify src-1 as a factor that promotes robustness of the AP positional system that instructs appropriate regeneration.
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Affiliation(s)
- Nicolle A Bonar
- Department of Molecular Biosciences, Northwestern University, Evanston, IL 60208, USA
| | - David I Gittin
- Department of Molecular Biosciences, Northwestern University, Evanston, IL 60208, USA
| | - Christian P Petersen
- Department of Molecular Biosciences, Northwestern University, Evanston, IL 60208, USA.,Robert Lurie Comprehensive Cancer Center, Northwestern University, Evanston, IL 60208, USA
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3
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Dolan CP, Yang TJ, Zimmel K, Imholt F, Qureshi O, Falck A, Gregory J, Mayes M, Ritchie K, Koester H, Daniel B, Yan M, Yu L, Suva LJ, Gaddy D, Dawson LA, Muneoka K, Brunauer R. Epimorphic regeneration of the mouse digit tip is finite. Stem Cell Res Ther 2022; 13:62. [PMID: 35130972 DOI: 10.1186/s13287-022-02741-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2021] [Accepted: 01/24/2022] [Indexed: 11/30/2022] Open
Abstract
Background Structural regeneration of amputated appendages by blastema-mediated, epimorphic regeneration is a process whose mechanisms are beginning to be employed for inducing regeneration. While epimorphic regeneration is classically studied in non-amniote vertebrates such as salamanders, mammals also possess a limited ability for epimorphic regeneration, best exemplified by the regeneration of the distal mouse digit tip. A fundamental, but still unresolved question is whether epimorphic regeneration and blastema formation is exhaustible, similar to the finite limits of stem-cell mediated tissue regeneration. Methods In this study, distal mouse digits were amputated, allowed to regenerate and then repeatedly amputated. To quantify the extent and patterning of the regenerated digit, the digit bone as the most prominent regenerating element in the mouse digit was followed by in vivo µCT. Results Analyses revealed that digit regeneration is indeed progressively attenuated, beginning after the second regeneration cycle, but that the pattern is faithfully restored until the end of the fourth regeneration cycle. Surprisingly, when unamputated digits in the vicinity of repeatedly amputated digits were themselves amputated, these new amputations also exhibited a similarly attenuated regeneration response, suggesting a systemic component to the amputation injury response. Conclusions In sum, these data suggest that epimorphic regeneration in mammals is finite and due to the exhaustion of the proliferation and differentiation capacity of the blastema cell source. Supplementary Information The online version contains supplementary material available at 10.1186/s13287-022-02741-2.
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Wang X, Harrison A. A general principle for spontaneous genetic symmetry breaking and pattern formation within cell populations. J Theor Biol 2021; 526:110809. [PMID: 34119496 DOI: 10.1016/j.jtbi.2021.110809] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2021] [Revised: 05/23/2021] [Accepted: 06/07/2021] [Indexed: 10/21/2022]
Abstract
Elements within biological systems interact and frequently self-organize from initially disordered states into highly structured patterns. The local self-activation and lateral inhibition mechanism, derived from the coupling between two reacting and diffusing chemicals, has been believed to be one of the main causes for biological pattern formation. Graded positional information can be produced by the limited diffusion of one single signaling molecule through cell populations with no pre-patterns being required. We demonstrate, using multiscale computations, that spontaneous symmetry breaking can be driven within expanding and non-expanding cell populations, without local self-enhancement of activators and long-range inhibition. Instead, cells can self-organize into structured gene patterns via a combination of timing gene expression in cells and the graded positional information which has been coupled to the gene expression. We show that the genetic symmetry breaking in expanding E. coli populations occurs at a critical colony size, which is independent of the cell doubling time but scales with the diffusion speed of the signaling molecule. We also show the quasi-3D structure of gene patterns, and observe that the wave length of periodic genetic stripes is in proportion to the genetic oscillation cycle time and in inverse proportion to cell doubling time. Our results provide insights into relevant biological development processes.
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Affiliation(s)
- Xiaoliang Wang
- College of Life Sciences, Zhejiang University, Hangzhou 310058, China; School of Physical Sciences, University of Science and Technology of China, Hefei 230026, China.
| | - Andrew Harrison
- Department of Mathematical Sciences, University of Essex, Colchester CO4 3SQ, UK.
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5
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Busby L, Aceituno C, McQueen C, Rich CA, Ros MA, Towers M. Sonic hedgehog specifies flight feather positional information in avian wings. Development 2020; 147:147/9/dev188821. [PMID: 32376617 PMCID: PMC7225127 DOI: 10.1242/dev.188821] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2020] [Accepted: 03/24/2020] [Indexed: 11/24/2022]
Abstract
Classical tissue recombination experiments performed in the chick embryo provide evidence that signals operating during early limb development specify the position and identity of feathers. Here, we show that Sonic hedgehog (Shh) signalling in the embryonic chick wing bud specifies positional information required for the formation of adult flight feathers in a defined spatial and temporal sequence that reflects their different identities. We also reveal that Shh signalling is interpreted into specific patterns of Sim1 and Zic transcription factor expression, providing evidence of a putative gene regulatory network operating in flight feather patterning. Our data suggest that flight feather specification involved the co-option of the pre-existing digit patterning mechanism and therefore uncovers an embryonic process that played a fundamental step in the evolution of avian flight.
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Affiliation(s)
- Lara Busby
- Department of Biomedical Science, University of Sheffield, Western Bank, Sheffield S10 2TN, UK
| | - Cristina Aceituno
- Instituto de Biomedicina y Biotecnología de Cantabria, IBBTEC (CSIC-Universidad de Cantabria - SODERCAN), 39011 Santander, Spain
| | - Caitlin McQueen
- Department of Biomedical Science, University of Sheffield, Western Bank, Sheffield S10 2TN, UK
| | - Constance A. Rich
- Department of Biomedical Science, University of Sheffield, Western Bank, Sheffield S10 2TN, UK
| | - Maria A. Ros
- Instituto de Biomedicina y Biotecnología de Cantabria, IBBTEC (CSIC-Universidad de Cantabria - SODERCAN), 39011 Santander, Spain,Departamento de Anatomía y Biología Celular, Facultad de Medicina, Universidad de Cantabria, 39011 Santander, Spain,Authors for correspondence (; )
| | - Matthew Towers
- Department of Biomedical Science, University of Sheffield, Western Bank, Sheffield S10 2TN, UK
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Abstract
There is much talk about information in biology. In developmental biology, this takes the form of "positional information," especially in the context of morphogen-based pattern formation. Unfortunately, the concept of "information" is rarely defined in any precise manner. Here, we provide two alternative interpretations of "positional information," and examine the complementary meanings and uses of each concept. Positional information defined as Shannon information helps us understand decoding and error propagation in patterning systems. General relativistic positional information, in contrast, provides a metric to assess the output of pattern-forming mechanisms. Both interpretations provide powerful conceptual tools that do not compete, but are best used in combination to gain a proper mechanistic understanding of robust patterning.
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Affiliation(s)
- Johannes Jaeger
- Complexity Science Hub (CSH), Vienna, Austria; Department of Molecular Evolution & Development, University of Vienna, Vienna, Austria.
| | - Berta Verd
- Department of Genetics, University of Cambridge, Cambridge, United Kingdom
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7
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Abstract
In order to contribute to the appropriate tissues during development, cells need to know their position within the embryo. This positional information is conveyed by gradients of signaling molecules, termed morphogens, that are produced in specific regions of the embryo and induce concentration-dependent responses in target tissues. Positional information is remarkably robust, and embryos often develop with the correct proportions even if large parts of the embryo are removed. In this Review, we discuss classical embryological experiments and modern quantitative analyses that have led to mechanistic insights into how morphogen gradients adapt, scale and properly pattern differently sized domains. We analyze these experimental findings in the context of mathematical models and synthesize general principles that apply to multiple systems across species and developmental stages.
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Affiliation(s)
- Daniel Čapek
- Systems Biology of Development Group, Friedrich Miescher Laboratory of the Max Planck Society, Max-Planck-Ring 9, 72076 Tübingen Germany
| | - Patrick Müller
- Systems Biology of Development Group, Friedrich Miescher Laboratory of the Max Planck Society, Max-Planck-Ring 9, 72076 Tübingen Germany .,Modeling Tumorigenesis Group, Translational Oncology Division, Eberhard Karls University Tübingen, Otfried-Müller-Strasse 10, 72076 Tübingen Germany
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8
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Abstract
Two phrases attributed to Lewis Wolpert - 'positional information' and 'The French Flag Model' - have become so intertwined that they are now used almost interchangeably. Here, I argue that this represents an unfortunate oversimplification of Wolpert's ideas that arose gradually in the developmental biology community, some significant time after his key papers were published. In contrast to common belief, Wolpert did not use the phrase French Flag 'Model' but instead introduced the French Flag 'Problem'. This famous metaphor was not a proposal of how patterning works, but rather an abstraction of the question to be addressed. More specifically, the French flag metaphor was an attempt to de-couple the problem from the multiple possible models that could solve it. In this spirit, Wolpert's first article on this topic also proposed (in addition to the well-known gradient model) an alternative solution to the French Flag Problem that was self-organising and had no gradients, and in which each cell 'cannot compute where it is in the system', i.e. there is no positional information. I discuss the history and evolution of these terms, and how they influence the way we study patterning.
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Affiliation(s)
- James Sharpe
- EMBL Barcelona, Carrer Dr. Aiguader 88, Barcelona 08003, Spain
- ICREA Research Professor, Catalan Institute for Research and Advanced Studies, Passeig Lluís Companys 23, 08010 Barcelona, Spain
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9
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Stigler RG, Becker K, Hasanov E, Hörmann R, Gassner R, Lepperdinger G. Osteocyte numbers decrease only in postcranial but not in cranial bones in humans of advanced age. Ann Anat 2019; 226:57-63. [PMID: 31330307 DOI: 10.1016/j.aanat.2019.06.006] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2019] [Revised: 06/24/2019] [Accepted: 06/25/2019] [Indexed: 12/29/2022]
Abstract
BACKGROUND Bone ageing is governed by the linked activities of short-lived osteoblasts and osteoclasts in conjunction with long-lived osteocytes present in osseous structure. Besides their maintenance function, osteogenic cells also gain specific positional information, which may potentially trigger ageing-associated cellular deviations in terminally differentiated osteocytes differently in cranial versus postcranial tissues. METHODS We therefore investigated bone taken from deceased aged humans explanted at five distinct anatomical positions throughout the body and assessed physical and biological determinants applying radiologic and histologic measures. RESULTS We were able to show that significantly more osteocytes reside in aged cortical bone at cranial positions than within axial or limb skeleton. These cellular states and conditions were not found in the corresponding trabecular bone, where osteocyte numbers remain also high at postcranial positions. Parallel comparative analyses of bone microstructure as analyzed by means of computer tomography showed no significant differences. CONCLUSIONS Considering differences and commonalities regarding the bone samples, such as loading, mechanisms of ossification or the surrounding stromal cell compartment, our findings indicate that positional information laid down during ontogenetic processes is instructive during the entire life thus potentially also moulding spatial-specific mechanistic distinctions of bone ageing.
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Affiliation(s)
- Robert G Stigler
- Department of Oral and Maxillofacial Surgery, Medical University Innsbruck, Anichstraße 35, 6020 Innsbruck, Austria
| | - Kathrin Becker
- Department of Orthodontics, Universitätsklinikum Düsseldorf, Morrenstr. 5, 40225 Düsseldorf, Germany.
| | - Elvin Hasanov
- Department of Oral and Maxillofacial Surgery, Medical University Innsbruck, Anichstraße 35, 6020 Innsbruck, Austria
| | - Romed Hörmann
- Division of Clinical and Functional Anatomy, Medical University Innsbruck, Anichstraße 35, 6020 Innsbruck, Austria
| | - Robert Gassner
- Department of Oral and Maxillofacial Surgery, Medical University Innsbruck, Anichstraße 35, 6020 Innsbruck, Austria
| | - Günter Lepperdinger
- Department of Biosciences, University Salzburg, Hellbrunnerstr 34, 5020 Salzburg, Austria
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10
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Vieira WA, McCusker CD. Hierarchical pattern formation during amphibian limb regeneration. Biosystems 2019; 183:103989. [PMID: 31295535 DOI: 10.1016/j.biosystems.2019.103989] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2019] [Revised: 07/03/2019] [Accepted: 07/06/2019] [Indexed: 12/28/2022]
Abstract
In 1901 T.H. Morgan proposed in "Regeneration" that pattern formation in amphibian limb regeneration is a stepwise process. Since, biologist have continued to piece together the molecular components of this process to better understand the "patterning code" responsible for regenerate formation. Within this context, several different models have been proposed; however, all are based on one of two underlying hypotheses. The first is the "morphogen hypothesis" that dictates that pattern emerges from localized expression of signaling molecules, which produce differing position-specific cellular responses in receptive cells depending on the intensity of the signal. The second hypothesis is that cells in the remaining tissues retain memory of their patterning information, and use this information to generate new cells with the missing positional identities. A growing body of evidence supports the possibility that these two mechanisms are not mutually exclusive. Here, we propose our theory of hierarchical pattern formation, which consists of 4 basic steps. The first is the existence of cells with positional memory. The second is the communication of positional information through cell-cell interactions in a regeneration-permissive environment. The third step is the induction of molecular signaling centers. And the last step is the interpretation of these signals by specialized cell types to ultimately restore the limb in its entirety. Biological codes are intertwined throughout this model, and we will discuss their multiple roles and mechanisms.
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Affiliation(s)
- Warren A Vieira
- Department of Biology, University of Massachusetts, Boston, MA, USA
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11
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Surkova S, Sokolkova A, Kozlov K, Nuzhdin SV, Samsonova M. Quantitative analysis reveals genotype- and domain- specific differences between mRNA and protein expression of segmentation genes in Drosophila. Dev Biol 2019; 448:48-58. [PMID: 30629954 DOI: 10.1016/j.ydbio.2019.01.006] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2018] [Revised: 12/12/2018] [Accepted: 01/04/2019] [Indexed: 10/27/2022]
Abstract
In many biological systems gene expression at mRNA and protein levels is not identical. Rigorous comparison of such differences on a spatio-temporal scale is still not feasible by high-throughput transcriptomic and proteomic analyses of early embryo development. Here, we characterize differences between mRNA and protein expression of Drosophila segmentation genes at the level of individual gene expression domains. We obtained quantitative imaging data on expression of gap genes gt and hb and pair-rule gene eve for Drosophila wild type embryos, Kr null mutants and Kr+/Kr- heterozygotes. To compare mRNA and protein expression we use several criteria including difference in amplitude and positions of expression domains, pattern shape and positional variability. For a number of gene expression domains we show examples where protein expression does not repeat mRNA expression even after a temporal delay. We calculated time delays between eve pattern formation at the level of mRNA and protein for wild type embryos, Kr mutants and Kr+/Kr- heterozygotes. We detect that in wild type embryos, the amplitudes of eve stripes 3 and 7 do not differ significantly at the level of mRNA, however, stripe 3 is higher than stripe 7 at the protein level. We further show that hb mRNA and protein expression in both anterior and posterior domains significantly differs at specific time points. The formation of hb PS4 stripe at the mRNA level proceeds five times faster than at the level of protein. With regard to spatial expression, we show that the offset between posterior gt mRNA and protein domains is much larger in Kr mutants than in wild type embryos and heterozygotes. Finally, we analyze differences in positional variability of eve stripe 7 expression in Kr mutants and Kr+/Kr- heterozygotes at the level of mRNA and protein. These results enable further perspectives to uncover mechanisms underlying discrepancies between mRNA and protein expression in early embryo.
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Affiliation(s)
- Svetlana Surkova
- Peter the Great St. Petersburg Polytechnic University, Polytechnicheskaya, 29, St. Petersburg 195251, Russia.
| | - Alena Sokolkova
- Peter the Great St. Petersburg Polytechnic University, Polytechnicheskaya, 29, St. Petersburg 195251, Russia
| | - Konstantin Kozlov
- Peter the Great St. Petersburg Polytechnic University, Polytechnicheskaya, 29, St. Petersburg 195251, Russia
| | - Sergey V Nuzhdin
- Peter the Great St. Petersburg Polytechnic University, Polytechnicheskaya, 29, St. Petersburg 195251, Russia; Section of Molecular and Computational Biology, University of Southern California, Los Angeles 90089, CA, USA
| | - Maria Samsonova
- Peter the Great St. Petersburg Polytechnic University, Polytechnicheskaya, 29, St. Petersburg 195251, Russia.
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Botella-López A, Garcia-Lopez R, Pombero A, Martinez S. Radial glia fibers translate Fgf8 morphogenetic signals to generate a thalamic nuclear complex protomap in the mantle layer. Brain Struct Funct 2019; 224:661-79. [PMID: 30470893 DOI: 10.1007/s00429-018-1794-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2017] [Accepted: 11/09/2018] [Indexed: 01/25/2023]
Abstract
Thalamic neurons are distributed between different nuclear groups of the thalamic multinuclear complex; they develop topologically ordered specific projections that convey information on voluntary motor programs and sensory modalities to functional areas in the cerebral cortex. Since thalamic neurons present a homogeneous morphology, their functional specificity is derived from their afferent and efferent connectivity. Adequate development of thalamic afferent and efferent connections depends on guide signals that bind receptors in nuclear neuropils and axonal growth cones, respectively. These are finally regulated by regionalization processes in the thalamic neurons, codifying topological information. In this work, we studied the role of Fgf8 morphogenetic signaling in establishing the molecular thalamic protomap, which was revealed by Igsf21, Pde10a and Btbd3 gene expression in the thalamic mantle layer. Fgf8 signaling activity was evidenced by pERK expression in radial glia cells and fibers, which may represent a scaffold that translates neuroepithelial positional information to the mantle layer. In this work, we describe the fact that Fgf8-hypomorphic mice did not express pERK in radial glia cells and fibers and presented disorganized thalamic regionalization, increasing neuronal death in the ventro-lateral thalamus and strong disruption of thalamocortical projections. In conclusion, Fgf8 encodes the positional information required for thalamic nuclear regionalization and the development of thalamocortical projections.
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Beloussov LV, Gordon R. Two ways for interpreting Driesch's law: " Positional information" and morphogenetic fields. Biosystems 2018; 173:7-9. [PMID: 30222992 DOI: 10.1016/j.biosystems.2018.09.005] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2018] [Revised: 09/11/2018] [Accepted: 09/12/2018] [Indexed: 11/24/2022]
Abstract
The late Lev V. Beloussov wrote a 2005 textbook The Foundations of General Embryology which is available in Russian. In 2003 he prepared an excellent, annotated translation of the part of his manuscript for this book on distinguishing positional information models from morphogenetic field models of embryogenesis, which is reproduced here verbatim. He concluded: "…the PI [positional information] concept has no predictive value, and cannot be thus regarded as a scientific theory".
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14
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Abstract
Theoretical and computational modelling are crucial to understand dynamics of embryonic development. In this tutorial chapter, we describe two models of gene networks performing time-dependent acquisition of positional information under control of a dynamic morphogen: a toy-model of a bistable gene under control of a morphogen, allowing for the numerical computation of a simple Waddington's epigenetic landscape, and a recently published model of gap genes in Tribolium under control of multiple enhancers. We present detailed commented implementations of the models using python and jupyter notebooks.
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Affiliation(s)
- Laurent Jutras-Dubé
- McGill University, Ernest Rutherford Physics Building, 3600 rue University, H3A2T8, Montreal, QC, Canada
| | - Adrien Henry
- McGill University, Ernest Rutherford Physics Building, 3600 rue University, H3A2T8, Montreal, QC, Canada
| | - Paul François
- McGill University, Ernest Rutherford Physics Building, 3600 rue University, H3A2T8, Montreal, QC, Canada
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15
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Tewary M, Ostblom J, Prochazka L, Zulueta-Coarasa T, Shakiba N, Fernandez-Gonzalez R, Zandstra PW. A stepwise model of reaction-diffusion and positional information governs self-organized human peri-gastrulation-like patterning. Development 2017; 144:4298-4312. [PMID: 28870989 PMCID: PMC5769627 DOI: 10.1242/dev.149658] [Citation(s) in RCA: 83] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2017] [Accepted: 08/23/2017] [Indexed: 12/15/2022]
Abstract
How position-dependent cell fate acquisition occurs during embryogenesis is a central question in developmental biology. To study this process, we developed a defined, high-throughput assay to induce peri-gastrulation-associated patterning in geometrically confined human pluripotent stem cell (hPSC) colonies. We observed that, upon BMP4 treatment, phosphorylated SMAD1 (pSMAD1) activity in the colonies organized into a radial gradient. We developed a reaction-diffusion (RD)-based computational model and observed that the self-organization of pSMAD1 signaling was consistent with the RD principle. Consequent fate acquisition occurred as a function of both pSMAD1 signaling strength and duration of induction, consistent with the positional-information (PI) paradigm. We propose that the self-organized peri-gastrulation-like fate patterning in BMP4-treated geometrically confined hPSC colonies arises via a stepwise model of RD followed by PI. This two-step model predicted experimental responses to perturbations of key parameters such as colony size and BMP4 dose. Furthermore, it also predicted experimental conditions that resulted in RD-like periodic patterning in large hPSC colonies, and rescued peri-gastrulation-like patterning in colony sizes previously thought to be reticent to this behavior.
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Affiliation(s)
- Mukul Tewary
- Institute of Biomaterials and Biomedical Engineering (IBBME), University of Toronto, Toronto, Ontario, M5S 3E1, Canada
- Collaborative Program in Developmental Biology, University of Toronto, Toronto, Ontario, M5S 3E1, Canada
- Terrence Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Toronto, Ontario, M5S 3E1, Canada
| | - Joel Ostblom
- Institute of Biomaterials and Biomedical Engineering (IBBME), University of Toronto, Toronto, Ontario, M5S 3E1, Canada
- Terrence Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Toronto, Ontario, M5S 3E1, Canada
| | - Laura Prochazka
- Institute of Biomaterials and Biomedical Engineering (IBBME), University of Toronto, Toronto, Ontario, M5S 3E1, Canada
- Terrence Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Toronto, Ontario, M5S 3E1, Canada
| | - Teresa Zulueta-Coarasa
- Institute of Biomaterials and Biomedical Engineering (IBBME), University of Toronto, Toronto, Ontario, M5S 3E1, Canada
- Ted Rogers Centre for Heart Research, University of Toronto, Toronto, Ontario, M5G 1M1, Canada
| | - Nika Shakiba
- Institute of Biomaterials and Biomedical Engineering (IBBME), University of Toronto, Toronto, Ontario, M5S 3E1, Canada
- Terrence Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Toronto, Ontario, M5S 3E1, Canada
| | - Rodrigo Fernandez-Gonzalez
- Institute of Biomaterials and Biomedical Engineering (IBBME), University of Toronto, Toronto, Ontario, M5S 3E1, Canada
- Collaborative Program in Developmental Biology, University of Toronto, Toronto, Ontario, M5S 3E1, Canada
- Ted Rogers Centre for Heart Research, University of Toronto, Toronto, Ontario, M5G 1M1, Canada
- Department of Cell and Systems Biology, University of Toronto, Toronto, Ontario, M5S 3G5, Canada
| | - Peter W Zandstra
- Institute of Biomaterials and Biomedical Engineering (IBBME), University of Toronto, Toronto, Ontario, M5S 3E1, Canada
- Collaborative Program in Developmental Biology, University of Toronto, Toronto, Ontario, M5S 3E1, Canada
- Terrence Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Toronto, Ontario, M5S 3E1, Canada
- Department of Chemical Engineering and Applied Chemistry, University of Toronto, Toronto, Ontario, M5S 3ES, Canada
- Medicine by Design: A Canada First Research Excellence Fund Program, University of Toronto, Toronto, Ontario, M5S 3E1, Canada
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16
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Pickering J, Towers M. Inhibition of Shh signalling in the chick wing gives insights into digit patterning and evolution. Development 2017; 143:3514-3521. [PMID: 27702785 PMCID: PMC5087615 DOI: 10.1242/dev.137398] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2016] [Accepted: 08/11/2016] [Indexed: 11/25/2022]
Abstract
In an influential model of pattern formation, a gradient of Sonic hedgehog (Shh) signalling in the chick wing bud specifies cells with three antero-posterior positional values, which give rise to three morphologically different digits by a self-organizing mechanism with Turing-like properties. However, as four of the five digits of the mouse limb are morphologically similar in terms of phalangeal pattern, it has been suggested that self-organization alone could be sufficient. Here, we show that inhibition of Shh signalling at a specific stage of chick wing development results in a pattern of four digits, three of which can have the same number of phalanges. These patterning changes are dependent on a posterior extension of the apical ectodermal ridge, and this also allows the additional digit to arise from the Shh-producing cells of the polarizing region – an ability lost in ancestral theropod dinosaurs. Our analyses reveal that, if the specification of antero-posterior positional values is curtailed, self-organization can then produce several digits with the same number of phalanges. We present a model that may give important insights into how the number of digits and phalanges has diverged during the evolution of avian and mammalian limbs. Highlighted Article: In the chick wing, the relative timing of the specification of antero-posterior positional values and self-organising mechanisms determines digit patterning and identity.
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Affiliation(s)
- Joseph Pickering
- Bateson Centre, Department of Biomedical Science, University of Sheffield, Western Bank, Sheffield S10 2TN, UK
| | - Matthew Towers
- Bateson Centre, Department of Biomedical Science, University of Sheffield, Western Bank, Sheffield S10 2TN, UK
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17
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Wolf B, Horn LC, Höckel M. Anogenital lichen sclerosus: Change of tissue position as pathogenetic factor. Gynecol Oncol Rep 2017; 20:73-74. [PMID: 28349117 PMCID: PMC5357701 DOI: 10.1016/j.gore.2017.03.003] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/31/2017] [Revised: 03/08/2017] [Accepted: 03/10/2017] [Indexed: 11/26/2022] Open
Abstract
•Lichen sclerosus in females primarily involves the hairless anogenital skin.•Skin tissue outside this area is constitutionally not at risk for lichen sclerosus.•Transplantation into the vulvar field may turn skin susceptible to lichen sclerosus.•Tissue inherent positional information might affect lichen sclerosus susceptibility.
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Affiliation(s)
- Benjamin Wolf
- Department of Obstetrics and Gynecology, Leipzig University Hospital, Germany
| | | | - Michael Höckel
- Department of Obstetrics and Gynecology, Leipzig University Hospital, Germany
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18
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McCusker CD, Diaz-Castillo C, Sosnik J, Q Phan A, Gardiner DM. Cartilage and bone cells do not participate in skeletal regeneration in Ambystoma mexicanum limbs. Dev Biol 2016; 416:26-33. [PMID: 27316294 DOI: 10.1016/j.ydbio.2016.05.032] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2016] [Revised: 05/20/2016] [Accepted: 05/27/2016] [Indexed: 02/08/2023]
Abstract
The Mexican Axolotl is one of the few tetrapod species that is capable of regenerating complete skeletal elements in injured adult limbs. Whether the skeleton (bone and cartilage) plays a role in the patterning and contribution to the skeletal regenerate is currently unresolved. We tested the induction of pattern formation, the effect on cell proliferation, and contributions of skeletal tissues (cartilage, bone, and periosteum) to the regenerating axolotl limb. We found that bone tissue grafts from transgenic donors expressing GFP fail to induce pattern formation and do not contribute to the newly regenerated skeleton. Periosteum tissue grafts, on the other hand, have both of these activities. These observations reveal that skeletal tissue does not contribute to the regeneration of skeletal elements; rather, these structures are patterned by and derived from cells of non-skeletal connective tissue origin.
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Affiliation(s)
| | - Carlos Diaz-Castillo
- Department of Developmental and Cell Biology, University of California at Irvine, CA 92602, USA
| | - Julian Sosnik
- Department of Interdisciplinary Engineering, Wentworth Institute of Technology, Boston, MA 02115, USA
| | - Anne Q Phan
- Department of Cellular and Molecular Medicine, University of California San Diego, CA 92093, USA
| | - David M Gardiner
- Department of Developmental and Cell Biology, University of California at Irvine, CA 92602, USA
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19
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Brown LE, Middleton AM, King JR, Loose M. Multicellular Mathematical Modelling of Mesendoderm Formation in Amphibians. Bull Math Biol 2016; 78:436-67. [PMID: 26934886 DOI: 10.1007/s11538-016-0150-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2015] [Accepted: 01/04/2016] [Indexed: 10/22/2022]
Abstract
The earliest cell fate decisions in a developing embryo are those associated with establishing the germ layers. The specification of the mesoderm and endoderm is of particular interest as the mesoderm is induced from the endoderm, potentially from an underlying bipotential group of cells, the mesendoderm. Mesendoderm formation has been well studied in an amphibian model frog, Xenopus laevis, and its formation is driven by a gene regulatory network (GRN) induced by maternal factors deposited in the egg. We have recently demonstrated that the axolotl, a urodele amphibian, utilises a different topology in its GRN to specify the mesendoderm. In this paper, we develop spatially structured mathematical models of the GRNs governing mesendoderm formation in a line of cells. We explore several versions of the model of mesendoderm formation in both Xenopus and the axolotl, incorporating the key differences between these two systems. Model simulations are able to reproduce known experimental data, such as Nodal expression domains in Xenopus, and also make predictions about how the positional information derived from maternal factors may be interpreted to drive cell fate decisions. We find that whilst cell-cell signalling plays a minor role in Xenopus, it is crucial for correct patterning domains in axolotl.
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20
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Abstract
During early development in Drosophila, the spatial information of maternal gradients is translated into discrete transcriptional states determining cell fate. Information transfer depends on reproducibility of the gradients themselves, as well as the ability of cells to accurately measure and utilize morphogen concentrations in biologically meaning ways. In the following essay, these issues are discussed in context of the Bicoid gradient.
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Affiliation(s)
- Eric Wieschaus
- Molecular Biology Department, HHMI, Princeton University, Princeton, New Jersey, USA.
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21
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McCusker CD, Gardiner DM. Understanding positional cues in salamander limb regeneration: implications for optimizing cell-based regenerative therapies. Dis Model Mech 2014; 7:593-9. [PMID: 24872456 PMCID: PMC4036467 DOI: 10.1242/dmm.013359] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Regenerative medicine has reached the point where we are performing clinical trials with stem-cell-derived cell populations in an effort to treat numerous human pathologies. However, many of these efforts have been challenged by the inability of the engrafted populations to properly integrate into the host environment to make a functional biological unit. It is apparent that we must understand the basic biology of tissue integration in order to apply these principles to the development of regenerative therapies in humans. Studying tissue integration in model organisms, where the process of integration between the newly regenerated tissues and the ‘old’ existing structures can be observed and manipulated, can provide valuable insights. Embryonic and adult cells have a memory of their original position, and this positional information can modify surrounding tissues and drive the formation of new structures. In this Review, we discuss the positional interactions that control the ability of grafted cells to integrate into existing tissues during the process of salamander limb regeneration, and discuss how these insights could explain the integration defects observed in current cell-based regenerative therapies. Additionally, we describe potential molecular tools that can be used to manipulate the positional information in grafted cell populations, and to promote the communication of positional cues in the host environment to facilitate the integration of engrafted cells. Lastly, we explain how studying positional information in current cell-based therapies and in regenerating limbs could provide key insights to improve the integration of cell-based regenerative therapies in the future.
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Affiliation(s)
- Catherine D McCusker
- Francisco J. Ayala School of Biological Sciences, Department of Developmental and Cell Biology, University of California Irvine, CA 92602, USA.
| | - David M Gardiner
- Francisco J. Ayala School of Biological Sciences, Department of Developmental and Cell Biology, University of California Irvine, CA 92602, USA
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22
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Held LI Jr, Heup MA, Sappington JM, Peters SD. Interactions of decapentaplegic, wingless, and Distal-less in the Drosophila leg. ACTA ACUST UNITED AC 1994; 203:310-9. [PMID: 28305824 DOI: 10.1007/BF00457802] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/1993] [Revised: 09/01/1993] [Accepted: 10/14/1993] [Indexed: 10/26/2022]
Abstract
The genes decapentaplegic, wingless, and Distalless appear to be instrumental in constructing the anatomy of the adult Drosophila leg. In order to investigate how these genes function and whether they act coordinately, we analyzed the leg phenotypes of the single mutants and their inter se double mutant compounds. In decapentaplegic the tarsi frequently exhibit dorsal deficiencies which suggest that the focus of gene action may reside dorsally rather than distally. In wingless the tarsal hinges are typically duplicated along with other dorsal structures, confirming that the hinges arise dorsally. The plane of symmetry in double-ventral duplications caused by decapentaplegic is virtually the same as the plane in double-dorsal duplications caused by wingless. It divides the fate map into two parts, each bisected by the dorsoventral axis. In the double mutant decapentaplegic wingless the most ventral and dorsal tarsal structures are missing, consistent with the notion that both gene products function as morphogens. In wingless Distal-less compounds the legs are severely truncated, indicating an important interaction between these genes. Distal-less and decapentaplegic manifest a relatively mild synergism when combined.
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23
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Groell AL, Gardiner DM, Bryant SV. Stability of positional identity of axolotl blastema cells in vitro. ACTA ACUST UNITED AC 1993; 202:170-175. [PMID: 28305994 DOI: 10.1007/bf00365307] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/1992] [Accepted: 10/28/1992] [Indexed: 11/30/2022]
Abstract
Previous grafting experiments have demonstrated that cells from non-contiguous positions within developing and regenerating limbs differ in a property referred to as positional identity. The goal of this study was to determine how long the positional identity of axolotl limb blastema cells is stable during culture in vitro. We have developed an assay for posterior positional properties such that blastema cells can be cultured and then grafted into anterior positions in host blastemas, to determine if they can stimulate supernumerary digit formation. We report that posterior blastema cells are able to maintain their positional identities for at least a week in culture. In addition, we observed that blastema cells are able to rapidly degrade collagenous substrates in vitro, a property that apparently distinguishes them from limb cells of other vertebrates. These results provide information regarding the time boundaries within which the positional properties of blastema cells can be studied and manipulated in vitro.
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Affiliation(s)
- Anne Lesley Groell
- Developmental Biology Center and Department of Developmental and Cell Biology, University of California, 92717, Irvine, Irvine, CA, USA
| | - David M Gardiner
- Developmental Biology Center and Department of Developmental and Cell Biology, University of California, 92717, Irvine, Irvine, CA, USA
| | - Susan V Bryant
- Developmental Biology Center and Department of Developmental and Cell Biology, University of California, 92717, Irvine, Irvine, CA, USA
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24
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Pfannenstiel HD. The ventral nerve cord signals positional information during segment formation in an annelid (Ophryotrocha puerilis, Polychaeta). ACTA ACUST UNITED AC 1984; 194:32-36. [PMID: 28305190 DOI: 10.1007/bf00848951] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/1984] [Accepted: 07/17/1984] [Indexed: 11/29/2022]
Abstract
Growth and regeneration of segments were recorded in the polychaeteOphryotrocha puerilis. In one experiment the ventral nerve cords (VNCs) of the animals were cut; in the other, VNCs were left intact. VNC lesion in some specimens resulted in the outgrowth of supernumerary posterior parts from the site of operation. The characteristics of outgrowth of these supernumeraries were essentially the same as in normal specimens without double tails. After removing different numbers of caudal setigers, each of the two tails of the same double-tail monster independently regenerated different segment numbers within a given time. A simple model is proposed, allowing for these results, which states that the larval body of a polychaete consists of two regions with completely different positional values (episphere - prostomium; hyposphere - pygidium). During growth, segments with intervening positional values are intercalated. The rate of segment formation is high when there is a wide gap in positional values between pygidium and adjoining budding zone and the posteriormost segment. As this gap narrows, the growth rate slows down. During caudal regeneration, first of all a new pygidium with an adjacent proliferation zone is formed and the original positional value of the posteriormost part of the body is reestablished. Segment regeneration follows the same rules as segment growth. The results presented here also demonstrate that the VNC plays an important role, not only in segment proliferation, but also in signalling positional information to the newly formed segments.
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Affiliation(s)
- Hans-Dieter Pfannenstiel
- Institut für Allgemeine Zoologie, Freie Universität Berlin, Königin-Luise-Strasse 1-3, D-1000, Berlin 33
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25
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Kawamura K, Watanabe H. The role of parental positional information in the determination of antero-posterior polarity during palleal budding in ascidians. ACTA ACUST UNITED AC 1983; 192:28-36. [PMID: 28305331 DOI: 10.1007/bf00848766] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/1982] [Accepted: 09/27/1982] [Indexed: 11/30/2022]
Abstract
In the polysteelid ascidian,Polyandrocarpa misakiensis, buds can arise at any antero-posterior positional level around the basal margin of a functional zooid. In this study, each bud was cut into anterior and posterior halves along its proximo-distal axis. When an anterior half was combined with a posterior half from a higher (more posterior) level, the future zooid developed the same anteroposterior polarity as a normal bud. When the same operation was performed with a posterior half from a lower (more anterior) level, the antero-posterior polarity was inverted, resulting in a reversed body asymmetry (situs inversus viscerum). Bud polarity depended not on the size or the growth stage of the fragmented buds, but on the difference in parental positional levels from which respective buds to be fused had originated. Surgically constructed doublehalf buds developed a single polarity instead of a pattern reduplication. Insertion experiments with bud pieces showed that the gap between the positional levels was recognized at the proximal region of operated buds. The results of this study are inconsistent with the predictions of the polar coordinate model for pattern formation. It is concluded that a parent zooid possesses antero-posterior position-specific potential for determining bud polarity.
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Affiliation(s)
- Kazuo Kawamura
- Shimoda Marine Research Center, University of Tsukuba, Shimoda, 5-10-1, 415, Shizuoka, Japan
| | - Hiroshi Watanabe
- Shimoda Marine Research Center, University of Tsukuba, Shimoda, 5-10-1, 415, Shizuoka, Japan
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