Although the complexity of animal body plans increased greatly following the evolution of the mesoderm, interspecies genome comparisons show that the Cnidaria, which lack mesoderm, share the majority of their genes with the triploblastic Bilateria. Indeed, the genome of the diploblastic sea anemone Nematostella vectensis includes many genes implicated in mesoderm formation in the triploblasts. The aim of my thesis was to investigate the role of one such gene, the Nkx homeobox transcription factor ladybird (lbx1), in Xenopus and Nematostella using high throughput methods such as ChIP-Seq and RNA-Seq. Gain- and loss-of-function experiments in Xenopus revealed that lbx1 has a role in the development of primary neurons as well as in the formation of body wall and head muscles. During neurulation, lbx1 is expressed in the presumptive hindbrain, where it appears to regulate the size of the neural progenitor pool by activating sox2. Lbx1 is also capable of activating FGF signalling, as revealed by in vitro studies using mesoderm induction assays in animal caps. Downregulation of Nvlbx in Nematostella causes no effect on the ectoderm of Nvlbx morphants, but there are severe changes in the endoderm, including a loss of mesenteric muscle cells. RNA-Seq analysis of such embryos suggests that Nvlbx interferes with Notch or FGF signalling pathways, both of which have been implicated in Nematostella mesentery formation. Together, my functional studies and high throughput data suggest that lbx1 regulates FGF signalling in both Nematostella and Xenopus, and that this mechanism is likely to be conserved throughout the metazoan lineage.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:639656 |
| Date | January 2015 |
| Creators | Strobl, A. |
| Publisher | University College London (University of London) |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://discovery.ucl.ac.uk/1460751/ |
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