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The Evolution of Bilaterian Body‐Plan: Perspectives from the Developmental Genetics of the Acoela (Acoelomorpha)

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The Evolution of Bilaterian Body‐Plan: Perspectives from the Developmental Genetics of the Acoela (Acoelomorpha) The evolution of bilaterian body‐plan: perspectives from the developmental genetics of the Acoela (Acoelomorpha) Marta Chiodin ADVERTIMENT. La consulta d’aquesta tesi queda condicionada a l’acceptació de les següents condicions d'ús: La difusió d’aquesta tesi per mitjà del servei TDX (www.tdx.cat) i a través del Dipòsit Digital de la UB (diposit.ub.edu) ha estat autoritzada pels titulars dels drets de propietat intel·lectual únicament per a usos privats emmarcats en activitats d’investigació i docència. No s’autoritza la seva reproducció amb finalitats de lucre ni la seva difusió i posada a disposició des d’un lloc aliè al servei TDX ni al Dipòsit Digital de la UB. No s’autoritza la presentació del seu contingut en una finestra o marc aliè a TDX o al Dipòsit Digital de la UB (framing). Aquesta reserva de drets afecta tant al resum de presentació de la tesi com als seus continguts. En la utilització o cita de parts de la tesi és obligat indicar el nom de la persona autora. ADVERTENCIA. La consulta de esta tesis queda condicionada a la aceptación de las siguientes condiciones de uso: La difusión de esta tesis por medio del servicio TDR (www.tdx.cat) y a través del Repositorio Digital de la UB (diposit.ub.edu) ha sido autorizada por los titulares de los derechos de propiedad intelectual únicamente para usos privados enmarcados en actividades de investigación y docencia. No se autoriza su reproducción con finalidades de lucro ni su difusión y puesta a disposición desde un sitio ajeno al servicio TDR o al Repositorio Digital de la UB. No se autoriza la presentación de su contenido en una ventana o marco ajeno a TDR o al Repositorio Digital de la UB (framing). Esta reserva de derechos afecta tanto al resumen de presentación de la tesis como a sus contenidos. En la utilización o cita de partes de la tesis es obligado indicar el nombre de la persona autora. WARNING. On having consulted this thesis you’re accepting the following use conditions: Spreading this thesis by the TDX (www.tdx.cat) service and by the UB Digital Repository (diposit.ub.edu) has been authorized by the titular of the intellectual property rights only for private uses placed in investigation and teaching activities. Reproduction with lucrative aims is not authorized nor its spreading and availability from a site foreign to the TDX service or to the UB Digital Repository. Introducing its content in a window or frame foreign to the TDX service or to the UB Digital Repository is not authorized (framing). Those rights affect to the presentation summary of the thesis as well as to its contents. In the using or citation of parts of the thesis it’s obliged to indicate the name of the author. The evolution of bilaterian body‐plan: perspectives from the developmental genetics of the Acoela (Acoelomorpha) MARTA CHIODIN TESIS DOCTORAL UNIVERTSITAT DE BARCELONA Facultat de Bilogía Departemento de Genética Programa de Doctordado: Genética The evolution of bilaterian body‐plan: perspectives from the developmental genetics of the Acoela (Acoelomorpha) ‘La evolución de los eje corporales: perspectivas de la genética del desarrollo de los acelos (Acoelomorpha)’ Memória presentada por Marta Chiodin para acceder al título de Doctor por la Univerisdad de Barcelona, bajo la direccón del Doctor Pedro Martínez Serra Marta Chiodin Barcelona, Noviembre de 2012 EL DIRECTOR DE LA TESIS Dr. Pedro Martínez Serra Investigador ICREA Facultad de Biología Universidad de Barcelona TABLE OF CONTENTS Introduction……………………………………......................................................... 1 1. The Acoela……………………………………………................................................ 3 1.1 Habitat and Ecology………………………………………...................................... 3 1.2 Morphology…………………………………………………......................................... 4 1.2.1 Digestive system…………………………………………....................................... 5 1.2.2 Nervous system………………………………………............................................. 6 1.2.3 Musculature............................................................................................................ 8 1.2.4 Reproductive system......................................................................................... 9 1.2.5 Stem cells system................................................................................................ 12 1.3 Regeneration, reproduction and life cycle.................................................. 12 1.4 Development............................................................................................................ 13 1.5 Phylogeny.................................................................................................................. 14 1.6 Ancestral and derived traits within the Acoelomorpha........................ 17 1.7 Species included in this study............................................................................ 20 1.7.1 Symsagittifera roscoffensis............................................................................... 20 1.7.2 Isodiametra pulchra........................................................................................... 21 2. Animals: bodyplans, molecules and phylogenetic hipótesis......................................................................................................................... 23 2.1 Metazoa and Eumetazoa novelties.................................................................. 23 2.2 The Bilateria: the achievement of tremendously divergent body plans.................................................................................................................................... 25 2.3 The Eubilateria.......................................................................................................... 27 2.4 Body cavities and segmentation........................................................................ 28 2.5 Old and new phylogenies: internal revolutions of astonishing impact.................................................................................................................................... 29 3. Hypothesis on bilaterian evolution................................................................. 32 3.1 The acoeloid/planuloid theory............................................................................ 33 3.2 The archycoelomate hypothesis and conflicting concepts to the acoeloid theory.................................................................................................................................... 34 4. The mesoderm........................................................................................................ 35 4.1 Schizocoely and enterocoely: how does the mesoderm develop (and evolved)?............................................................................................................................... 37 4.2 Body cavities, connective tissues and muscles....................................... ..... 39 5. The Musculature...................................................................................................... 41 5.1 Evolution of muscles............................................................................................... 42 5.2 The sliding filaments.............................................................................................. 43 5.3 Smooth and striated muscles: differences in the ultrastructure and in the molecular regulation of contraction........................................................................ 46 5.4 The mesodermal gene regulatory network and the scopes of this thesis............................................................................................................................................ 48 Aims of the study......................................................................................................... 50 INFORME DEL DIRECTOR SOBRE ELS ARTICLES PUBLICATS................................................................................................................... 54 Publications............................................................................................................... 61 Resúmen del primer artículo, R1...................................................................... 79 Resúmen del segundo artículo, R2.................................................................... 125 Resúmen del tercer artículo, R3....................................................... 141 Resúmen del cuarto artículo, R4.......................................................... 163 Discussion................................................................................................ 165 1. Convenience of the model species................................................... 167 2. On the status of the acoels within the Acoelomorpha (Xenoturbellida+(Nemertodermatida+Acoela)): the significance of the nervous and the reproductive systems.......................................................................... 169 3. Mesodermal genes in acoels.......................................................................... 171 4. The molecular architecture of the acoel musculature............................... 174 5. Do acoels have a conserved bilaterian mesoderm gene regulatory network?............................................................................................................................ 179 6. Did the acoelomorph have a coelomate ancestor? Evidences from mesodermal gene expression patterns................................................................. 182 7. The acoelomorph gonads: a connection to the coelom or
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