On the orchestration of dorsal closure in Drosophila melanogaster : from tissue-scale control to cellular-scale remodeling
The vast diversity of life on Earth develops from relatively uniform beginnings via self-organised movements occurring between groups of cells. Whilst the variety of shapes resulting from morphogenesis is boundless, the number of distinct geometrical and topological changes that it comprises, are li...
| Autor: | |
|---|---|
| Tipo de recurso: | tesis doctoral |
| Estado: | Versión publicada |
| Fecha de publicación: | 2016 |
| País: | España |
| Institución: | CBUC, CESCA |
| Repositorio: | TDR. Tesis Doctorales en Red |
| OAI Identifier: | oai:www.tdx.cat:10803/586069 |
| Acceso en línea: | http://hdl.handle.net/10803/586069 |
| Access Level: | acceso abierto |
| Palabra clave: | Dorsal Closure Biomechanics Morphogenesis Actomyosin Pulsation Oscillation Epithelia Cadherin Junction 575 |
| Sumario: | The vast diversity of life on Earth develops from relatively uniform beginnings via self-organised movements occurring between groups of cells. Whilst the variety of shapes resulting from morphogenesis is boundless, the number of distinct geometrical and topological changes that it comprises, are limited. The control of biological form arises from an interplay between molecular biology and biomechanics. In this work we adopt a biophysical approach to study the regulation of a topological transformation that occurrs during the development of the fruit fly Drosophila melanogaster. Shortly before the Drosophila embryo transitions into a larva, it first covers its entire body in a single epidermal tissue layer. To achieve this, two layers of epidermis stretch laterally around the embryo and fuse dorsally, sealing a gap that was previously filled by a dying, pulsatile tissue, the amnioserosa (AS). This process is known as dorsal closure, and has drawn significant interest as a model system for other tissue fusion events, such as wound healing and neural tube closure. In this work, we first consider the global control of the process, deriving a biophysical description of the system from first physical principles: namely a force balance at the two corners (canthi) of the opening, and the Young- Laplace relationship around its contour. This represents an advancement on previous work in terms of the simplicity of the model, and the introduction of a term for AS volume loss to a two-dimensional description. In the second part of this thesis, we focus on the role of the pulsatile behaviour of the AS. We report on a new experimental assay for mechanically perturbing the Drosophila embryo. Combining this with the use of a novel method for extracting quantitative information from confocal cell images, we investigate the response of the AS to mechanical stretch. Finally, we propose a dual role for cortical myosin flows in the AS, both to offer structural supportjunctions are stretched, and to promote endocytotically mediated removal of excess junctions. |
|---|