<> "The repository administrator has not yet configured an RDF license."^^ . <> . . "The evolution of the neural crest from an annelid perspective:\r\nconserved cell types and signaling pathways in Platynereis dumerilii"^^ . "The neural crest is indisputably one of the major vertebrate innovations.\r\nNeural crest arises at the neural plate border and is the source of many cell types, such as those of the\r\nperipheral nervous system (sensory, autonomic neurons and supporting cells), pigments and cartilage. This\r\nregion of the neural plate also gives rise to Rohon Beard cells (RBc, primary sensory neurons) that\r\ndifferentiate from the same precursor cells of the neural crest (Rossi, Kaji, & Artinger, 2009), (Jacobson,\r\n1981).\r\nDespite the recent proposal for neural crest-like cells in basal chordates (Jeffery, Strickler, & Yamamoto,\r\n2004), and the postulation of the origin of neural crest from migrating Rohon Beard cells -like cells, the\r\nevolution of the neural crest remains obscure. The aim of my PhD was to shed light on the evolution of such\r\na special cell population in bilaterians.\r\nUsing classical whole mount in situs, Edu pulse experiments, live imaging and drug treatments I studied the\r\ndevelopment of the pax3/7+ lateral neuroectoderm of the marine worm Platynereis dumerilii. I used\r\nPlatynereis because it is a protostome that retains ancestral features and it has been successfully used in\r\nprevious studies to investigate cell type evolution.\r\nI investigated the lateral trunk region because it has been recently proposed that this domain corresponds\r\ntopologically and molecularly to the dorsal neural tube, where the vertebrate neural crest originates (Denes\r\net al., 2007)\r\nI found that the pax3/7+ territory is set very early in development and expresses Rohon Beard\r\ncells and neural crest specific genes, such as prdm1-a , msx, ap-2 and snail. Furthermore, I found that\r\ncanonical Wnt signaling controls the patterning of the annelid lateral neuroectdoderm, as in vertebrates.\r\nNext, I analyzed the fate of the cells emerging from this lateral territory. I found that sensory differentiation\r\ngenes are turned on in ngn+ precursor neurons in a temporal sequence, similar to the one occurring in the\r\nneural crest derived sensory neurons (Marmigère & Ernfors, 2007), (Lallemend & Ernfors, 2012). The annelid\r\nneurons that arise from the lateral pax3/7+ domain have molecular features of the Rohon Beard-like cells and\r\nvisceral sensory neurons. I found that also putative supporting cells ensheathing the axons arise\r\nperipherally.\r\nNext, I asked whether the other typical cell types that are neural crest-derived in vertebrates are present in\r\nPlatynereis. I found that MitF + melanoblasts , putative enteric neurons as well as collagenous skeleton are\r\nalso present in Platynereis, but apparently do not arise from the lateral domain.\r\nThe development, survival and axon-pathfinding of the neural crest derived-sensory neurons depends on\r\nthe neurotrophic signaling (Davies, 1994), (Gershon, 1994), (Tessarollo, 1998), (Sieber-Blum,\r\n1998),(Ernsberger, 2009) Furthermore, the evolution of the neural crest has been associated with the\r\nemergence of this pathway, considered for long time a vertebrate innovation (Wittbrodt, 2007). This\r\nprompted me to search for the neurotrophic molecules in Platynereis dumerilii. I found that all the molecules\r\nof the canonical neurotrophic signaling are present in the worm and show vertebrate-like molecular\r\nfeatures. They are widely expressed in the nervous system, therefore they likely act during neuronal\r\ndevelopment. This finding refutes the belief that neurotrophic signaling is a chordate novelty: a hypothesis\r\nbased on a lack of conservation in other protostomes such as Drosophila (Pulido, Campuzano, Koda,\r\nModolell, & Barbacid, 1992)and Lymnea (Beck et al., 2003) .\r\nCollectively, these annelid data suggest that the formation of Rohon Beard-like sensory neurons, putative\r\nvisceral sensory neurons and supporting cells were already a feature of the cells emerging from the lateral\r\nneuroectoderm (a neural plate-like territory) at the dawn of bilaterians. A gradual co-option of genetic\r\nmodules acting in other tissues into the neural plate-like territory might have driven the evolution of bona\r\nfine neural crest."^^ . "2013" . . . . . . . "Antonella"^^ . "Lauri"^^ . "Antonella Lauri"^^ . . . . . . "The evolution of the neural crest from an annelid perspective:\r\nconserved cell types and signaling pathways in Platynereis dumerilii (PDF)"^^ . . . "AntonellaLauri_PhD_thesis_2012_3.pdf"^^ . . . "The evolution of the neural crest from an annelid perspective:\r\nconserved cell types and signaling pathways in Platynereis dumerilii (Other)"^^ . . . . . . "indexcodes.txt"^^ . . . "The evolution of the neural crest from an annelid perspective:\r\nconserved cell types and signaling pathways in Platynereis dumerilii (Other)"^^ . . . . . . "The evolution of the neural crest from an annelid perspective:\r\nconserved cell types and signaling pathways in Platynereis dumerilii (Other)"^^ . . . . . . "The evolution of the neural crest from an annelid perspective:\r\nconserved cell types and signaling pathways in Platynereis dumerilii (Other)"^^ . . . . . . "The evolution of the neural crest from an annelid perspective:\r\nconserved cell types and signaling pathways in Platynereis dumerilii (Other)"^^ . . . . . 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