Control of two morphogenetic processes during "Drosophila melanogaster" metamorphosis: fusion of imaginal discs and ecdysis
Author
Simon, EleanorAdvisor
Guerrero Vega, IsabelEntity
UAM. Departamento de Biología Molecular; Centro de Biología Molecular Severo Ochoa (CBM)Date
2016-11-25Funded by
El presente trabajo ha sido realizado con las ayuda de un contrato a cargo del proyecto de investigación Marie Curie Action (FP7- 2008) European Community (ITN 238186) titulado “HEALING” entre los años 2009-2013, de un contrato a cargo del Proyecto de investigación del MCINN (BFU2011-25987) titulado “Mechanisms of Hedgehog signaling” durante el 2014 y de un contrato a cargo del Proyecto de investigación del MINECO (BFU2014-59438) titulado “Cellular bases and dynamics of intercellular communication in morphogenesis” durante los años 2015 y 2016.Subjects
Drosophilas - Tesis doctoral; Biología y Biomedicina / BiologíaNote
Tesis Doctoral inédita leída en la Universidad Autónoma de Madrid, Facultad de Ciencias, Departamento de Biología Molecular. Fecha de lectura: 25-11-2016Esta tesis tiene embargado el acceso al texto completo hasta el 25-05-2018
Esta obra está bajo una licencia de Creative Commons Reconocimiento-NoComercial-SinObraDerivada 4.0 Internacional.
Abstract
Arthropods cuticle constitutes an external skeleton or exoskeleton. It has a protective function, such as
support or defense against predator, but also has a physiologic role by preventing from desiccation or by
sensing its environment among others. Arthropods suffer various molting throughout their lifetime. Their
cuticle is highly rigid and has to be periodically shed to allow the animal to grow or to change its form. This
process highly stereotyped, referred as ecdysis, is followed by a postecdysis period which permits the cuticle
to become mature.
Drosophila melanogaster is a holometabolous insect. Its life cycle starts with the fecundated egg. At the end
of the embryogenesis, the embryo hatches to give rise to a small size larva. Two molts are necessary to
obtain the grown larva, which then stop moving. The cuticle of the larvae is then shed and used as a cocoon,
called pupal case, where a complete metamorphosis (from the Greek meta “change” and morphe “form”)
occurs. At the final ecdysis (eclosion), the adult fly emerges. During the post-eclosion behavioral sequence
the newly formed and soft cuticle get tanned, that is to say get hardened and darken, and the wings extend.
Adult thorax derives from a couple of larval structures, which are of ectodermal origin, called wing imaginal
discs. During the metamorphosis, they migrate dorsally and fuse at the midline in a two slide fasteners
manner similar to a wound healing. During this Thesis, we studied the implication of the Hox gene
Antennapedia (Antp) during thorax closure. We found that Antp expression is restricted to the cells that
initiate this morphogenetic event and alteration of its expression leads to a split thorax. Our results indicate
that this phenotype is associated to a missregulation of JNK signaling which in turn affects actin cytoskeleton
organization and filopodia formation needed in the leading edge cells for tissue migration.
We also focus our interest on a later Drosophila developmental stage, the post-eclosion. The mechanism
underlying the post-eclosion sequence is known to be controlled by the neuropeptide Bursicon, which is
synthesized by a subset of neurons called CCAP. We found that the transcription factor Opa is expressed in
the CCAP cells and that downregulation of opa expression mimics the phenotype of alteration in Bursicon
expression. Our data point to a requirement of Opa expression in the CCAP cell to prevent them from
apoptosis. Besides, we identified Opa as the first uncovered positive regulator of Bursicon expression.
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