| 1. |
- Lara-Ramirez, Ricardo, et al.
(författare)
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A Notch-regulated proliferative stem cell zone in the developing spinal cord is an ancestral vertebrate trait
- 2019
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Ingår i: Development. - : Company of Biologists. - 0950-1991 .- 1477-9129. ; 146:1
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Tidskriftsartikel (refereegranskat)abstract
- Vertebrates have evolved the most sophisticated nervous systems we know. These differ from the nervous systems of invertebrates in several ways, including the evolution of new cell types, and the emergence and elaboration of patterning mechanisms to organise cells in time and space. Vertebrates also generally have many more cells in their central nervous systems than invertebrates, and an increase in neural cell number may have contributed to the sophisticated anatomy of the brain and spinal cord. Here, we study how increased cell number evolved in the vertebrate central nervous system, investigating the regulation of cell proliferation in the lamprey spinal cord. Markers of proliferation show that a ventricular progenitor zone is found throughout the lamprey spinal cord. We show that inhibition of Notch signalling disrupts the maintenance of this zone. When Notch is blocked, progenitor cells differentiate precociously, the proliferative ventricular zone is lost and differentiation markers become expressed throughout the spinal cord. Comparison with other chordates suggests that the emergence of a persistent Notch-regulated proliferative progenitor zone was a crucial step for the evolution of vertebrate spinal cord complexity.
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| 2. |
- Lara-Ramirez, Ricardo, et al.
(författare)
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Characterization of two neurogenin genes from the brook lamprey lampetra planeri and their expression in the lamprey nervous system
- 2015
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Ingår i: Developmental Dynamics. - : Wiley. - 1058-8388 .- 1097-0177. ; 244:9, s. 1096-1108
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Tidskriftsartikel (refereegranskat)abstract
- Background: Neurogenins are required for the specification of neuronal precursors and regulate the expression of basic Helix-Loop-Helix genes involved in neuronal differentiation. Jawed vertebrates possess three Neurogenin paralogy groups and their combined expression covers the entire nervous system, apart from the autonomic nervous system. Results: Here we report the isolation of two Neurogenin genes, LpNgnA and LpNgnB, from the lamprey Lampetra planeri. Phylogenetic analyses show both genes have orthologues in other lamprey species and in a hagfish. Neither gene shows evidence of orthology to specific jawed vertebrate Neurogenin paralogues. LpNgnA is expressed in the ventricular zone of regions of the brain and spinal cord, with expression in the brain demarcating brain sub-compartments including the pallium, tegmentum, tectum, and dorsal thalamus. In the peripheral nervous system, LpNgnA is expressed in cranial sensory placodes and their derivatives, and in the dorsal root ganglia. LpNgnB is expressed transiently in placodal head ectoderm and throughout the central nervous system in early development, and in a small population cells that form part of the macula. Conclusions: Combined, LpNgnA and LpNgnB were detected in most cell populations marked by Neurogenin gene expression in jawed vertebrates, with the exception of the cerebellum, retina and the non-neural expression sites. (c) 2015 Wiley Periodicals, Inc.
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| 3. |
- Lara-Ramirez, Ricardo, et al.
(författare)
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The structure, splicing, synteny and expression of lamprey COE genes and the evolution of the COE gene family in chordates
- 2017
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Ingår i: Development, Genes and Evolution. - : SPRINGER. - 0949-944X .- 1432-041X. ; 227:5, s. 319-338
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Tidskriftsartikel (refereegranskat)abstract
- COE genes encode transcription factors that have been found in all metazoans examined to date. They possess a distinctive domain structure that includes a DNA-binding domain (DBD), an IPT/TIG domain and a helix-loop-helix (HLH) domain. An intriguing feature of the COE HLH domain is that in jawed vertebrates it is composed of three helices, compared to two in invertebrates. We report the isolation and expression of two COE genes from the brook lamprey Lampetra planeri and compare these to COE genes from the lampreys Lethenteron japonicum and Petromyzon marinus. Molecular phylogenetic analyses do not resolve the relationship of lamprey COE genes to jawed vertebrate paralogues, though synteny mapping shows that they all derive from duplication of a common ancestral genomic region. All lamprey genes encode conserved DBD, IPT/TIG and HLH domains; however, the HLH domain of lamprey COE-A genes encodes only two helices while COE-B encodes three helices. We also identified COE-B splice variants encoding either two or three helices in the HLH domain, along with other COE-A and COE-B splice variants affecting the DBD and C-terminal transactivation regions. In situ hybridisation revealed expression in the lamprey nervous system including the brain, spinal cord and cranial sensory ganglia. We also detected expression of both genes in mesenchyme in the pharyngeal arches and underlying the notochord. This allows us to establish the primitive vertebrate expression pattern for COE genes and compare this to that of invertebrate chordates and other animals to develop a model for COE gene evolution in chordates.
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| 4. |
- Papadogiannis, Vasileios, et al.
(författare)
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Evolution of the expression and regulation of the nuclear hormone receptor ERR gene family in the chordate lineage
- 2023
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Ingår i: Developmental Biology. - 0012-1606 .- 1095-564X. ; 504, s. 12-24
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Tidskriftsartikel (refereegranskat)abstract
- The Estrogen Related Receptor (ERR) nuclear hormone receptor genes have a wide diversity of roles in vertebrate development. In embryos, ERR genes are expressed in several tissues, including the central and peripheral nervous systems. Here we seek to establish the evolutionary history of chordate ERR genes, their expression and their regulation. We examine ERR expression in mollusc, amphioxus and sea squirt embryos, finding the single ERR orthologue is expressed in the nervous system in all three, with muscle expression also found in the two chordates. We show that most jawed vertebrates and lampreys have four ERR paralogues, and that vertebrate ERR genes were ancestrally linked to Estrogen Receptor genes. One of the lamprey paralogues shares conserved expression domains with jawed vertebrate ERRγ in the embryonic vestibuloacoustic ganglion, eye, brain and spinal cord. Hypothesising that conserved expression derives from conserved regulation, we identify a suite of pan-vertebrate conserved non-coding sequences in ERR introns. We use transgenesis in lamprey and chicken embryos to show that these sequences are regulatory and drive reporter gene expression in the nervous system. Our data suggest an ancient association between ERR and the nervous system, including expression in cells associated with photosensation and mechanosensation. This includes the origin in the vertebrate common ancestor of a suite of regulatory elements in the 3’ introns that drove nervous system expression and have been conserved from this point onwards.
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| 5. |
- Papadogiannis, Vasileios, et al.
(författare)
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Hmx gene conservation identifies the origin of vertebrate cranial ganglia
- 2022
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Ingår i: Nature. - : Springer Nature. - 0028-0836 .- 1476-4687. ; 605:7911, s. 701-705
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Tidskriftsartikel (refereegranskat)abstract
- The evolutionary origin of vertebrates included innovations in sensory processing associated with the acquisition of a predatory lifestyle1. Vertebrates perceive external stimuli through sensory systems serviced by cranial sensory ganglia, whose neurons arise predominantly from cranial placodes; however, the understanding of the evolutionary origin of placodes and cranial sensory ganglia is hampered by the anatomical differences between living lineages and the difficulty in assigning homology between cell types and structures. Here we show that the homeobox transcription factor Hmx is a constitutive component of vertebrate sensory ganglion development and that in the tunicate Ciona intestinalis, Hmx is necessary and sufficient to drive the differentiation programme of bipolar tail neurons, cells previously thought to be homologues of neural crest2,3. Using Ciona and lamprey transgenesis, we demonstrate that a unique, tandemly duplicated enhancer pair regulated Hmx expression in the stem-vertebrate lineage. We also show notably robust vertebrate Hmx enhancer function in Ciona, demonstrating that deep conservation of the upstream regulatory network spans the evolutionary origin of vertebrates. These experiments demonstrate regulatory and functional conservation between Ciona and vertebrate Hmx, and point to bipolar tail neurons as homologues of cranial sensory ganglia.
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| 6. |
- Patthey, Cedric, et al.
(författare)
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Identification of molecular signatures specific for distinct cranial sensory ganglia in the developing chick
- 2016
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Ingår i: Neural Development. - : Springer Science and Business Media LLC. - 1749-8104. ; 11
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Tidskriftsartikel (refereegranskat)abstract
- Background: The cranial sensory ganglia represent populations of neurons with distinct functions, or sensory modalities. The production of individual ganglia from distinct neurogenic placodes with different developmental pathways provides a powerful model to investigate the acquisition of specific sensory modalities. To date there is a limited range of gene markers available to examine the molecular pathways underlying this process.Results: Transcriptional profiles were generated for populations of differentiated neurons purified from distinct cranial sensory ganglia using microdissection in embryonic chicken followed by FAC-sorting and RNAseq. Whole transcriptome analysis confirmed the division into somato- versus viscerosensory neurons, with additional evidence for subdivision of the somatic class into general and special somatosensory neurons. Cross-comparison of distinct ganglia transcriptomes identified a total of 134 markers, 113 of which are novel, which can be used to distinguish trigeminal, vestibulo-acoustic and epibranchial neuronal populations. In situ hybridisation analysis provided validation for 20/26 tested markers, and showed related expression in the target region of the hindbrain in many cases.Conclusions: One hundred thirty-four high-confidence markers have been identified for placode-derived cranial sensory ganglia which can now be used to address the acquisition of specific cranial sensory modalities.
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| 7. |
- Patthey, Cedric, et al.
(författare)
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The evolutionary history of vertebrate cranial placodes - I : Cell type evolution
- 2014
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Ingår i: Developmental Biology. - : Elsevier. - 0012-1606 .- 1095-564X. ; 389:1, s. 82-97
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Tidskriftsartikel (refereegranskat)abstract
- Vertebrate cranial placodes are crucial contributors to the vertebrate cranial sensory apparatus. Their evolutionary origin has attracted much attention from evolutionary and developmental biologists, yielding speculation and hypotheses concerning their putative homologues in other lineages and the developmental and genetic innovations that might have underlain their origin and diversification. In this article we first briefly review our current understanding of placode development and the cell types and structures they form. We next summarise previous hypotheses of placode evolution, discussing their strengths and caveats, before considering the evolutionary history of the various cell types that develop from placodes. In an accompanying review, we also further consider the evolution of ectodermal patterning. Drawing on data from vertebrates, tunicates, amphioxus, other bilaterians and cnidarians, we build these strands into a scenario of placode evolutionary history and of the genes, cells and developmental processes that underlie placode evolution and development. (C) 2014 Elsevier Inc. All rights reserved.
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