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Brad Davidson - One of the best experts on this subject based on the ideXlab platform.
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fibronectin contributes to notochord intercalation in the inVertebrate chordate ciona intestinalis
Evodevo, 2016Co-Authors: Fernando Segade, Christina D Cota, Amber Famiglietti, Brad DavidsonAbstract:Genomic analysis has upended chordate phylogeny, placing the tunicates as the sister group to the Vertebrates. This taxonomic rearrangement raises questions about the emergence of a tunicate/Vertebrate ancestor. Characterization of developmental genes uniquely shared by tunicates and Vertebrates is one promising approach for deciphering developmental shifts underlying acquisition of novel, ancestral traits. The matrix glycoprotein Fibronectin (FN) has long been considered a Vertebrate-specific gene, playing a major instructive role in Vertebrate embryonic development. However, the recent computational prediction of an orthologous “Vertebrate-like” Fn gene in the genome of a tunicate, Ciona savignyi, challenges this viewpoint suggesting that Fn may have arisen in the shared tunicate/Vertebrate ancestor. Here we verify the presence of a tunicate Fn ortholog. Transgenic reporter analysis was used to characterize a Ciona Fn enhancer driving expression in the notochord. Targeted knockdown in the notochord lineage indicates that FN is required for proper convergent extension. These findings suggest that acquisition of Fn was associated with altered notochord morphogenesis in the Vertebrate/tunicate ancestor.
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Fibronectin contributes to notochord intercalation in the inVertebrate chordate, Ciona intestinalis
EvoDevo, 2016Co-Authors: Fernando Segade, Amber Famiglietti, Christina Cota, Brad DavidsonAbstract:Background Genomic analysis has upended chordate phylogeny, placing the tunicates as the sister group to the Vertebrates. This taxonomic rearrangement raises questions about the emergence of a tunicate/Vertebrate ancestor. Results Characterization of developmental genes uniquely shared by tunicates and Vertebrates is one promising approach for deciphering developmental shifts underlying acquisition of novel, ancestral traits. The matrix glycoprotein Fibronectin (FN) has long been considered a Vertebrate-specific gene, playing a major instructive role in Vertebrate embryonic development. However, the recent computational prediction of an orthologous “Vertebrate-like” Fn gene in the genome of a tunicate, Ciona savignyi, challenges this viewpoint suggesting that Fn may have arisen in the shared tunicate/Vertebrate ancestor. Here we verify the presence of a tunicate Fn ortholog. Transgenic reporter analysis was used to characterize a Ciona Fn enhancer driving expression in the notochord. Targeted knockdown in the notochord lineage indicates that FN is required for proper convergent extension. Conclusions These findings suggest that acquisition of Fn was associated with altered notochord morphogenesis in the Vertebrate/tunicate ancestor.
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Fibronectin contributes to notochord intercalation in the inVertebrate chordate, Ciona
2016Co-Authors: Christina D Cota, Amber Famiglietti, Anna Cha, Brad DavidsonAbstract:Background: Genomic analysis has upended chordate phylogeny, placing the tunicates as the sister group to the Vertebrates. This taxonomic rearrangement raises questions about the emergence of a tunicate/Vertebrate ancestor. Results: Characterization of developmental genes uniquely shared by tunicates and Vertebrates is one promising approach for deciphering developmental shifts underlying acquisition of novel, ancestral traits. The matrix glycoprotein Fibronectin (FN) has long been considered a Vertebrate-specific gene, playing a major instructive role in verte brate embryonic development. However, the recent computational prediction of an orthologous “Vertebrate-like” Fn gene in the genome of a tunicate, Ciona savignyi, challenges this viewpoint suggesting that Fn may have arisen in the shared tunicate/Vertebrate ancestor. Here we verify the presence of a tunicate Fn ortholog. Transgenic reporter analysis was used to characterize a Ciona Fn enhancer driving expression in the notochord. Targeted knockdown in the notochord lineage indicates that FN is required for proper convergent extension. Conclusions: These findings suggest that acquisition of Fn was associated with altered notochord morphogenesis in the Vertebrate/tunicate ancestor.
Nori Satoh - One of the best experts on this subject based on the ideXlab platform.
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A genomewide survey of developmentally relevant genes in Ciona intestinalis
Development Genes and Evolution, 2003Co-Authors: Yasunori Sasakura, Naohito Takatori, Eiichi Shoguchi, Shuichi Wada, Ian A Meinertzhagen, Yutaka Satou, Nori SatohAbstract:Cell junctions and the extracellular matrix (ECM) are crucial components in intercellular communication. These systems are thought to have become highly diversified during the course of Vertebrate evolution. In the present study, we have examined whether the ancestral chordate already had such Vertebrate systems for intercellular communication, for which we have searched the genome of the ascidian Ciona intestinalis . From this molecular perspective, the Ciona genome contains genes that encode protein components of tight junctions, hemidesmosomes and connexin-based gap junctions, as well as of adherens junctions and focal adhesions, but it does not have those for desmosomes. The latter omission is curious, and the ascidian type-I cadherins may represent an ancestral form of the Vertebrate type-I cadherins and desmosomal cadherins, while Ci-Plakin may represent an ancestral protein of the Vertebrate desmoplakins and plectins. If this is the case, then ascidians may have retained ancestral desmosome-like structures, as suggested by previous electron-microscopic observations. In addition, ECM genes that have been regarded as Vertebrate-specific were also found in the Ciona genome. These results suggest that the last common ancestor shared by ascidians and Vertebrates, the ancestor of the entire chordate clade, had essentially the same systems of cell junctions as those in extant Vertebrates. However, the number of such genes for each family in the Ciona genome is far smaller than that in Vertebrate genomes. In Vertebrates these ancestral cell junctions appear to have evolved into more diverse, and possibly more complex, forms, compared with those in their urochordate siblings.
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A genomewide survey of developmentally relevant genes in Ciona intestinalis
Development Genes and Evolution, 2003Co-Authors: Yasunori Sasakura, Naohito Takatori, Eiichi Shoguchi, Shuichi Wada, Ian A Meinertzhagen, Yutaka Satou, Nori SatohAbstract:Cell junctions and the extracellular matrix (ECM) are crucial components in intercellular communication. These systems are thought to have become highly diversified during the course of Vertebrate evolution. In the present study, we have examined whether the ancestral chordate already had such Vertebrate systems for intercellular communication, for which we have searched the genome of the ascidian Ciona intestinalis . From this molecular perspective, the Ciona genome contains genes that encode protein components of tight junctions, hemidesmosomes and connexin-based gap junctions, as well as of adherens junctions and focal adhesions, but it does not have those for desmosomes. The latter omission is curious, and the ascidian type-I cadherins may represent an ancestral form of the Vertebrate type-I cadherins and desmosomal cadherins, while Ci-Plakin may represent an ancestral protein of the Vertebrate desmoplakins and plectins. If this is the case, then ascidians may have retained ancestral desmosome-like structures, as suggested by previous electron-microscopic observations. In addition, ECM genes that have been regarded as Vertebrate-specific were also found in the Ciona genome. These results suggest that the last common ancestor shared by ascidians and Vertebrates, the ancestor of the entire chordate clade, had essentially the same systems of cell junctions as those in extant Vertebrates. However, the number of such genes for each family in the Ciona genome is far smaller than that in Vertebrate genomes. In Vertebrates these ancestral cell junctions appear to have evolved into more diverse, and possibly more complex, forms, compared with those in their urochordate siblings.
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a genomewide survey of developmentally relevant genes in ciona intestinalis x genes for cell junctions and extracellular matrix
Development Genes and Evolution, 2003Co-Authors: Yasunori Sasakura, Naohito Takatori, Eiichi Shoguchi, Shuichi Wada, Ian A Meinertzhagen, Yutaka Satou, Nori SatohAbstract:: Cell junctions and the extracellular matrix (ECM) are crucial components in intercellular communication. These systems are thought to have become highly diversified during the course of Vertebrate evolution. In the present study, we have examined whether the ancestral chordate already had such Vertebrate systems for intercellular communication, for which we have searched the genome of the ascidian Ciona intestinalis. From this molecular perspective, the Ciona genome contains genes that encode protein components of tight junctions, hemidesmosomes and connexin-based gap junctions, as well as of adherens junctions and focal adhesions, but it does not have those for desmosomes. The latter omission is curious, and the ascidian type-I cadherins may represent an ancestral form of the Vertebrate type-I cadherins and desmosomal cadherins, while Ci-Plakin may represent an ancestral protein of the Vertebrate desmoplakins and plectins. If this is the case, then ascidians may have retained ancestral desmosome-like structures, as suggested by previous electron-microscopic observations. In addition, ECM genes that have been regarded as Vertebrate-specific were also found in the Ciona genome. These results suggest that the last common ancestor shared by ascidians and Vertebrates, the ancestor of the entire chordate clade, had essentially the same systems of cell junctions as those in extant Vertebrates. However, the number of such genes for each family in the Ciona genome is far smaller than that in Vertebrate genomes. In Vertebrates these ancestral cell junctions appear to have evolved into more diverse, and possibly more complex, forms, compared with those in their urochordate siblings.
Andrey G. Zaraisky - One of the best experts on this subject based on the ideXlab platform.
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The presence of Anf/Hesx1 homeobox gene in lampreys suggests that it could play an important role in emergence of telencephalon.
Scientific reports, 2016Co-Authors: Andrey V. Bayramov, Galina V. Ermakova, Fedor M. Eroshkin, A. V. Kucheryavyy, N. Y. Martynova, Andrey G. ZaraiskyAbstract:Accumulated evidence indicates that the core genetic mechanisms regulating early patterning of the brain rudiment in Vertebrates are very similar to those operating during development of the anterior region of inVertebrate embryos. However, the mechanisms underlying the morphological differences between the elaborate Vertebrate brain and its simpler inVertebrate counterpart remain poorly understood. Recently, we hypothesized that the emergence of the most anterior unit of the Vertebrate brain, the telencephalon, could be related to the appearance in Vertebrates’ ancestors of a unique homeobox gene, Anf/Hesx1(further Anf), which is absent from all inVertebrates and regulates the earliest steps of telencephalon development in Vertebrates. However, the failure of Anf to be detected in one of the most basal extant Vertebrate species, the lamprey, seriously compromises this hypothesis. Here, we report the cloning of Anf in three lamprey species and demonstrate that this gene is indeed expressed in embryos in the same pattern as in other Vertebrates and executes the same functions by inhibiting the expression of the anterior general regulator Otx2 in favour of the telencephalic regulator FoxG1. These results are consistent with the hypothesis that the Anf homeobox gene may have been important in the evolution of the telencephalon.
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the presence of anf hesx1 homeobox gene in lampreys suggests that it could play an important role in emergence of telencephalon
Scientific Reports, 2016Co-Authors: Andrey V. Bayramov, Galina V. Ermakova, Fedor M. Eroshkin, A. V. Kucheryavyy, N. Y. Martynova, Andrey G. ZaraiskyAbstract:Accumulated evidence indicates that the core genetic mechanisms regulating early patterning of the brain rudiment in Vertebrates are very similar to those operating during development of the anterior region of inVertebrate embryos. However, the mechanisms underlying the morphological differences between the elaborate Vertebrate brain and its simpler inVertebrate counterpart remain poorly understood. Recently, we hypothesized that the emergence of the most anterior unit of the Vertebrate brain, the telencephalon, could be related to the appearance in Vertebrates’ ancestors of a unique homeobox gene, Anf/Hesx1(further Anf), which is absent from all inVertebrates and regulates the earliest steps of telencephalon development in Vertebrates. However, the failure of Anf to be detected in one of the most basal extant Vertebrate species, the lamprey, seriously compromises this hypothesis. Here, we report the cloning of Anf in three lamprey species and demonstrate that this gene is indeed expressed in embryos in the same pattern as in other Vertebrates and executes the same functions by inhibiting the expression of the anterior general regulator Otx2 in favour of the telencephalic regulator FoxG1. These results are consistent with the hypothesis that the Anf homeobox gene may have been important in the evolution of the telencephalon.
David W. Mccauley - One of the best experts on this subject based on the ideXlab platform.
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Evolutionary and Developmental Associations of Neural Crest and Placodes in the Vertebrate Head: Insights From Jawless Vertebrates.
Frontiers in physiology, 2020Co-Authors: Joshua R. York, Tian Yuan, David W. MccauleyAbstract:Neural crest and placodes are key innovations of the Vertebrate clade. These cells arise within the dorsal ectoderm of all Vertebrate embryos and have the developmental potential to form many of the morphological novelties within the Vertebrate head. Each cell population has its own distinct developmental features and generates unique cell types. However, it is essential that neural crest and placodes associate together throughout embryonic development to coordinate the emergence of several features in the head, including almost all of the cranial peripheral sensory nervous system and organs of special sense. Despite the significance of this developmental feat, its evolutionary origins have remained unclear, owing largely to the fact that there has been little comparative (evolutionary) work done on this topic between the jawed Vertebrates and cyclostomes-the jawless lampreys and hagfishes. In this review, we briefly summarize the developmental mechanisms and genetics of neural crest and placodes in both jawed and jawless Vertebrates. We then discuss recent studies on the role of neural crest and placodes-and their developmental association-in the head of lamprey embryos, and how comparisons with jawed Vertebrates can provide insights into the causes and consequences of this event in early Vertebrate evolution.
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The origin and evolution of Vertebrate neural crest cells
Open biology, 2020Co-Authors: Joshua R. York, David W. MccauleyAbstract:The neural crest is a Vertebrate-specific migratory stem cell population that generates a remarkably diverse set of cell types and structures. Because many of the morphological, physiological and behavioural novelties of Vertebrates are derived from neural crest cells, it is thought that the origin of this cell population was an important milestone in early Vertebrate history. An outstanding question in the field of Vertebrate evolutionary-developmental biology (evo-devo) is how this cell type evolved in ancestral Vertebrates. In this review, we briefly summarize neural crest developmental genetics in Vertebrates, focusing in particular on the gene regulatory interactions instructing their early formation within and migration from the dorsal neural tube. We then discuss how studies searching for homologues of neural crest cells in inVertebrate chordates led to the discovery of neural crest-like cells in tunicates and the potential implications this has for tracing the pre-Vertebrate origins of the neural crest population. Finally, we synthesize this information to propose a model to explain the origin of neural crest cells. We suggest that at least some of the regulatory components of early stages of neural crest development long pre-date Vertebrate origins, perhaps dating back to the last common bilaterian ancestor. These components, originally directing neuroectodermal patterning and cell migration, served as a gene regulatory 'scaffold' upon which neural crest-like cells with limited migration and potency evolved in the last common ancestor of tunicates and Vertebrates. Finally, the acquisition of regulatory programmes controlling multipotency and long-range, directed migration led to the transition from neural crest-like cells in inVertebrate chordates to multipotent migratory neural crest in the first Vertebrates.
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Gliogenesis in lampreys shares gene regulatory interactions with oligodendrocyte development in jawed Vertebrates.
Developmental biology, 2018Co-Authors: Tian Yuan, Joshua R. York, David W. MccauleyAbstract:Abstract Glial cells in the nervous system regulate and support many functions related to neuronal activity. Understanding how the Vertebrate nervous system has evolved demands a greater understanding of the mechanisms controlling evolution and development of glial cells in basal Vertebrates. Among Vertebrate glia, oligodendrocytes form an insulating myelin layer surrounding axons of the central nervous system (CNS) in jawed Vertebrates. Jawless Vertebrates lack myelinated axons but it is unclear when oligodendrocytes or the regulatory mechanisms controlling their development evolved. To begin to investigate the evolution of mechanisms controlling glial development, we identified key genes required for the differentiation of oligodendrocytes in gnathostomes, including Nkx2.2, SoxE genes, and PDGFR, analyzed their expression, and used CRISPR/Cas9 genome editing to perturb their functions in a primitively jawless Vertebrate, the sea lamprey. We show in lamprey that orthologs required for oligodendrocyte development in jawed Vertebrates are expressed in the lamprey ventral neural tube, in similar locations where gnathostome oligodendrocyte precursor cells (OPC) originate. In addition, they appear to be under the control of conserved mechanisms that regulate OPC development in jawed Vertebrates and may also function in gliogenesis. Our results suggest that although oligodendrocytes first emerged in jawed Vertebrates, regulatory mechanisms required for their development predate the divergence of jawless and jawed Vertebrates.
Danny S. Tuckwell - One of the best experts on this subject based on the ideXlab platform.
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Fibrillar collagen: the key to Vertebrate evolution? A tale of molecular incest.
BioEssays, 2003Co-Authors: Ray Boot-handford, Danny S. TuckwellAbstract:Fibril-forming (fibrillar) collagens are extracellular matrix proteins conserved in all multicellular animals. Vertebrate members of the fibrillar collagen family are essential for the formation of bone and teeth, tissues that characterise Vertebrates. The potential role played by fibrillar collagens in Vertebrate evolution has not been considered previously largely because the family has been around since the sponge and it was unclear precisely how and when those particular members now found in Vertebrates first arose. We present evidence that the classical Vertebrate fibrillar collagens share a single common ancestor that arose at the very dawn of the Vertebrate world and prior to the associated genome duplication events. Furthermore, we present a model, 'molecular incest', that not only accounts for the characteristics of the modern day Vertebrate fibrillar collagen family but demonstrates the specific effects genome or gene duplications may have on the evolution of multimeric proteins in general.
