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Abstract
Body axis elongation and segmentation are major morphogenetic events that take place concomitantly during vertebrate embryonic development. Establishment of the final body plan requires tight coordination between these two key processes. In this review, we detail the cellular and molecular as well as the physical processes underlying body axis formation and patterning. We discuss how formation of the anterior region of the body axis differs from that of the posterior region. We describe the developmental mechanism of segmentation and the regulation of body length and segment numbers. We focus mainly on the chicken embryo as a model system. Its accessibility and relatively flat structure allow high-quality time-lapse imaging experiments, which makes it one of the reference models used to study morphogenesis. Additionally, we illustrate conservation and divergence of specific developmental mechanisms by discussing findings in other major embryonic model systems, such as mice, frogs, and zebrafish.
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Affiliation(s)
- Bertrand Bénazéraf
- Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), CNRS (UMR 7104), Université de Strasbourg, Illkirch F-67400, France;
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52
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53
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Reece JS, Mehta RS. Evolutionary history of elongation and maximum body length in moray eels (Anguilliformes: Muraenidae). Biol J Linn Soc Lond 2013. [DOI: 10.1111/bij.12098] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Affiliation(s)
- Joshua S. Reece
- Department of Ecology and Evolutionary Biology; Long Marine Lab; University of California; Santa Cruz; CA; 95060; USA
| | - Rita S. Mehta
- Department of Ecology and Evolutionary Biology; Long Marine Lab; University of California; Santa Cruz; CA; 95060; USA
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54
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Main steps of skeletal muscle development in the human. HANDBOOK OF CLINICAL NEUROLOGY 2013; 113:1299-310. [DOI: 10.1016/b978-0-444-59565-2.00002-2] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
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55
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Abstract
The elongated, snake-like skeleton, as it has convergently evolved in numerous reptilian and amphibian lineages, is from a developmental biologist’s point of view amongst the most fascinating anatomical peculiarities in the animal kingdom. This type of body plan is characterized by a greatly increased number of vertebrae, a reduction of skeletal regionalization along the primary body axis and loss of the limbs. Recent studies conducted on both mouse and snakes now hint at how changes inside the gene regulatory circuitries of the Hox genes and the somitogenesis clock likely underlie these striking departures from standard tetrapod morphology, suggesting scenarios by which snakes and other elongated species may have evolved from more ordinarily bodied ancestors.
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Affiliation(s)
- Joost M Woltering
- University of Geneva, Department of Genetics and Evolution, 30 quai Ernest Ansermet, 1211 CH, Genève, Switzerland
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56
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Genetic analysis of vertebral regionalization and number in medaka (Oryzias latipes) inbred lines. G3-GENES GENOMES GENETICS 2012; 2:1317-23. [PMID: 23173083 PMCID: PMC3484662 DOI: 10.1534/g3.112.003236] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/28/2012] [Accepted: 08/23/2012] [Indexed: 11/19/2022]
Abstract
Vertebral number is the most variable trait among vertebrates. In addition to the vertebral number, the ratio of abdominal to caudal vertebrae is a variable trait. The vertebral number and the ratio of abdominal to caudal vertebrae contribute to vertebrate diversity. It is very interesting to know how to determine the vertebral number and the ratio of abdominal to caudal vertebrae. In this study, we identify differences in the vertebral number and the ratio of abdominal vertebrae to vertebral number between two inbred lines of medaka, namely, Hd-rRII1 and Kaga. To identify the genetic factor of those differences, we performed quantitative trait locus (QTL) analysis for vertebral number and the ratio of abdominal vertebrae to vertebral number using 200 F2 fish. Our results show a suggestive QTL of the ratio of abdominal vertebrae to vertebral number on chromosome 15, and five QTL of vertebral number on chromosomes 1, 10, 11, 17, and 23. The QTL on chromosome 15 contains hoxDb cluster genes. The QTL of vertebral number include some genes related to the segmentation clock and axial elongation. In addition, we show that the difference in vertebral number between two inbred lines is derived from differences in the anteroposterior length of somites. Our results emphasize that the developmental process should be considered in genetic analyses for vertebral number.
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57
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Evolutionary concepts meet the neck of penguins (Aves: Sphenisciformes), towards a “survival strategy” for evo-devo. Theory Biosci 2012; 131:231-42. [DOI: 10.1007/s12064-012-0156-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2012] [Accepted: 06/03/2012] [Indexed: 01/07/2023]
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58
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McGraw PN, Menzinger M. Blocking and transmission of traveling flow-distributed-oscillation waves in an absolutely unstable flowing medium. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2012; 86:026208. [PMID: 23005846 DOI: 10.1103/physreve.86.026208] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/22/2011] [Indexed: 06/01/2023]
Abstract
For a flowing, self-oscillating medium, we study the competition between traveling flow-distributed-oscillation waves excited by periodic driving at the upstream boundary and bulk oscillations originating downstream from the boundary. As previously observed in the case of stationary driving, we find that there is a region in parameter space where boundary-driven traveling waves of sufficiently high amplitude can impose themselves on the entire medium despite the presence of an absolute instability, which otherwise tends to block information from upstream. For sufficiently low flow rates, however, the imposed waves are arrested at a nonlinear blocking transition. Unlike the stationary case, we find that the region of imposed waves extends well into regions where, according to the linear approximation, there should be no traveling waves at all. This suggests that the extinction of the traveling waves is analogous to a subcritical Hopf bifurcation.
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Affiliation(s)
- Patrick N McGraw
- Department of Chemistry, University of Toronto, Toronto, Ontario, Canada
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59
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Abstract
Many of the morphogenetic processes that occur during development in the mouse are based on cyclic events with defined time intervals, as exemplified by somitogenesis (every 2 h), hair cycles (every 25 d), and spermatogenesis (every 35 d). Among these events, somitogenesis is the most dynamic morphogenetic mechanism showing clear cyclicity during embryogenesis and is therefore a good system with which to review the synchronous and cyclic characteristics of developmental pathways. The metameric properties of the somites underpin the segmental properties along the anterior-posterior (AP) axis of the body. The periodicity of somites is controlled by the so-called segmentation clock operating in the presomitic mesoderm (PSM). This tissue contains the somite precursor cells that exist only during embryonic development. Both theoretical and experimental approaches have contributed to the understanding of the mechanism of somite segmentation. This article focuses on how the segmentation clock functions to organize the collective behavior of cells and how this information is translated into the spatial patterning of segmental somites. The interplay between signaling molecules that provides positional information and the transcription factors that respond to such positional cues are critical to the role of the segmentation clock and are discussed.
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60
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Whitcome KK. Functional implications of variation in lumbar vertebral count among hominins. J Hum Evol 2012; 62:486-97. [DOI: 10.1016/j.jhevol.2012.01.008] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2010] [Revised: 01/09/2012] [Accepted: 01/14/2012] [Indexed: 11/26/2022]
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61
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Keyte A, Smith KK. Heterochrony in somitogenesis rate in a model marsupial,Monodelphis domestica. Evol Dev 2012; 14:93-103. [DOI: 10.1111/j.1525-142x.2011.00524.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Anna Keyte
- Duke University; Department of Biology; Durham NC 27708 USA
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62
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Abstract
Taxonomic, morphological, and functional diversity are often discordant and independent components of diversity. A fundamental and largely unanswered question in evolutionary biology is why some clades diversify primarily in some of these components and not others. Dramatic variation in trunk vertebral numbers (14 to >300) among squamate reptiles coincides with different body shapes, and snake-like body shapes have evolved numerous times. However, whether increased evolutionary rates or numbers of vertebrae underlie body shape and taxonomic diversification is unknown. Using a supertree of squamates including 1375 species, and corresponding vertebral and body shape data, we show that increased rates of evolution in vertebral numbers have coincided with increased rates and disparity in body shape evolution, but not changes in rates of taxonomic diversification. We also show that the evolution of many vertebrae has not spurred or inhibited body shape or taxonomic diversification, suggesting that increased vertebral number is not a key innovation. Our findings demonstrate that lineage attributes such as the relaxation of constraints on vertebral number can facilitate the evolution of novel body shapes, but that different factors are responsible for body shape and taxonomic diversification.
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63
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Murray PJ, Maini PK, Baker RE. The clock and wavefront model revisited. J Theor Biol 2011; 283:227-38. [PMID: 21635902 DOI: 10.1016/j.jtbi.2011.05.004] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2010] [Revised: 01/24/2011] [Accepted: 05/03/2011] [Indexed: 01/12/2023]
Abstract
The currently accepted interpretation of the clock and wavefront model of somitogenesis is that a posteriorly moving molecular gradient sequentially slows the rate of clock oscillations, resulting in a spatial readout of temporal oscillations. However, while molecular components of the clocks and wavefronts have now been identified in the pre-somitic mesoderm (PSM), there is not yet conclusive evidence demonstrating that the observed molecular wavefronts act to slow clock oscillations. Here we present an alternative formulation of the clock and wavefront model in which oscillator coupling, already known to play a key role in oscillator synchronisation, plays a fundamentally important role in the slowing of oscillations along the anterior-posterior (AP) axis. Our model has three parameters which can be determined, in any given species, by the measurement of three quantities: the clock period in the posterior PSM, somite length and the length of the PSM. A travelling wavefront, which slows oscillations along the AP axis, is an emergent feature of the model. Using the model we predict: (a) the distance between moving stripes of gene expression; (b) the number of moving stripes of gene expression and (c) the oscillator period profile along the AP axis. Predictions regarding the stripe data are verified using existing zebrafish data. We simulate a range of experimental perturbations and demonstrate how the model can be used to unambiguously define a reference frame along the AP axis. Comparing data from zebrafish, chick, mouse and snake, we demonstrate that: (a) variation in patterning profiles is accounted for by a single nondimensional parameter; the ratio of coupling strengths; and (b) the period profile along the AP axis is conserved across species. Thus the model is consistent with the idea that, although the genes involved in pattern propagation in the PSM vary, there is a conserved patterning mechanism across species.
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Affiliation(s)
- Philip J Murray
- Centre for Mathematical Biology, Mathematical Institute, 24-29 St Giles', Oxford OX1 3LB, UK.
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64
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Nagai H, Mak SS, Weng W, Nakaya Y, Ladher R, Sheng G. Embryonic development of the emu, Dromaius novaehollandiae. Dev Dyn 2010; 240:162-75. [DOI: 10.1002/dvdy.22520] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
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65
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Ventral and sub-caudal scale counts are associated with macrohabitat use and tail specialization in viperid snakes. Evol Ecol 2010. [DOI: 10.1007/s10682-010-9432-z] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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66
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67
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Ward AB, Mehta RS. Axial Elongation in Fishes: Using Morphological Approaches to Elucidate Developmental Mechanisms in Studying Body Shape. Integr Comp Biol 2010; 50:1106-19. [DOI: 10.1093/icb/icq029] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
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68
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Müller J, Scheyer TM, Head JJ, Barrett PM, Werneburg I, Ericson PGP, Pol D, Sánchez-Villagra MR. Homeotic effects, somitogenesis and the evolution of vertebral numbers in recent and fossil amniotes. Proc Natl Acad Sci U S A 2010; 107:2118-23. [PMID: 20080660 PMCID: PMC2836685 DOI: 10.1073/pnas.0912622107] [Citation(s) in RCA: 131] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The development of distinct regions in the amniote vertebral column results from somite formation and Hox gene expression, with the adult morphology displaying remarkable variation among lineages. Mammalian regionalization is reportedly very conservative or even constrained, but there has been no study investigating vertebral count variation across Amniota as a whole, undermining attempts to understand the phylogenetic, ecological, and developmental factors affecting vertebral column variation. Here, we show that the mammalian (synapsid) and reptilian lineages show early in their evolutionary histories clear divergences in axial developmental plasticity, in terms of both regionalization and meristic change, with basal synapsids sharing the conserved axial configuration of crown mammals, and basal reptiles demonstrating the plasticity of extant taxa. We conducted a comprehensive survey of presacral vertebral counts across 436 recent and extinct amniote taxa. Vertebral counts were mapped onto a generalized amniote phylogeny as well as individual ingroup trees, and ancestral states were reconstructed by using squared-change parsimony. We also calculated the relationship between presacral and cervical numbers to infer the relative influence of homeotic effects and meristic changes and found no correlation between somitogenesis and Hox-mediated regionalization. Although conservatism in presacral numbers characterized early synapsid lineages, in some cases reptiles and synapsids exhibit the same developmental innovations in response to similar selective pressures. Conversely, increases in body mass are not coupled with meristic or homeotic changes, but mostly occur in concert with postembryonic somatic growth. Our study highlights the importance of fossils in large-scale investigations of evolutionary developmental processes.
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Affiliation(s)
- Johannes Müller
- Museum für Naturkunde – Leibniz-Institut für Evolutions- und Biodiversitätsforschung an der Humboldt-Universität zu Berlin, D-10115 Berlin, Germany
| | - Torsten M. Scheyer
- Paläontologisches Institut und Museum, Universität Zürich, CH-8006 Zürich, Switzerland
| | - Jason J. Head
- Department of Biology, University of Toronto Mississauga, Mississauga, ON L5L 1C6, Canada
| | - Paul M. Barrett
- Department of Palaeontology, Natural History Museum, London SW7 5BD, United Kingdom
| | - Ingmar Werneburg
- Paläontologisches Institut und Museum, Universität Zürich, CH-8006 Zürich, Switzerland
| | - Per G. P. Ericson
- Department of Vertebrate Zoology, Swedish Museum of Natural History, SE-10405 Stockholm, Sweden; and
| | - Diego Pol
- Consejo Nacional de Investigaciones Científicas y Técnicas, Museo Paleontológico Egidio Feruglio, Trelew CP 9100, Argentina
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69
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Suzuki D, Brandley MC, Tokita M. The mitochondrial phylogeny of an ancient lineage of ray-finned fishes (Polypteridae) with implications for the evolution of body elongation, pelvic fin loss, and craniofacial morphology in Osteichthyes. BMC Evol Biol 2010; 10:21. [PMID: 20100320 PMCID: PMC2825197 DOI: 10.1186/1471-2148-10-21] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2009] [Accepted: 01/25/2010] [Indexed: 12/02/2022] Open
Abstract
BACKGROUND The family Polypteridae, commonly known as "bichirs", is a lineage that diverged early in the evolutionary history of Actinopterygii (ray-finned fish), but has been the subject of far less evolutionary study than other members of that clade. Uncovering patterns of morphological change within Polypteridae provides an important opportunity to evaluate if the mechanisms underlying morphological evolution are shared among actinoptyerygians, and in fact, perhaps the entire osteichthyan (bony fish and tetrapods) tree of life. However, the greatest impediment to elucidating these patterns is the lack of a well-resolved, highly-supported phylogenetic tree of Polypteridae. In fact, the interrelationships of polypterid species have never been subject to molecular phylogenetic analysis. Here, we infer the first molecular phylogeny of bichirs, including all 12 recognized species and multiple subspecies using Bayesian analyses of 16S and cyt-b mtDNA. We use this mitochondrial phylogeny, ancestral state reconstruction, and geometric morphometrics to test whether patterns of morphological evolution, including the evolution of body elongation, pelvic fin reduction, and craniofacial morphology, are shared throughout the osteichthyan tree of life. RESULTS Our molecular phylogeny reveals 1) a basal divergence between Erpetoichthys and Polypterus, 2) polyphyly of P. endlicheri and P. palmas, and thus 3) the current taxonomy of Polypteridae masks its underlying genetic diversity. Ancestral state reconstructions suggest that pelvic fins were lost independently in Erpetoichthys, and unambiguously estimate multiple independent derivations of body elongation and shortening. Our mitochondrial phylogeny suggested species that have lower jaw protrusion and up-righted orbit are closely related to each other, indicating a single transformation of craniofacial morphology. CONCLUSION The mitochondrial phylogeny of polypterid fish provides a strongly-supported phylogenetic framework for future comparative evolutionary, physiological, ecological, and genetic analyses. Indeed, ancestral reconstruction and geometric morphometric analyses revealed that the patterns of morphological evolution in Polypteridae are similar to those seen in other osteichthyans, thus implying the underlying genetic and developmental mechanisms responsible for those patterns were established early in the evolutionary history of Osteichthyes. We propose developmental and genetic mechanisms to be tested under the light of this new phylogenetic framework.
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Affiliation(s)
- Dai Suzuki
- Department of Zoology, Graduate School of Science, Kyoto University, Sakyo, Kyoto, 606-8502 Japan
| | - Matthew C Brandley
- Department of Ecology and Evolutionary Biology, Yale University, New Haven, CT 06520-8105 USA
| | - Masayoshi Tokita
- Department of Zoology, Graduate School of Science, Kyoto University, Sakyo, Kyoto, 606-8502 Japan
- Graduate School of Life and Environmental Sciences, University of Tsukuba, Tsukuba, Ibaraki, 305-8572 Japan
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