This thesis establishes methods to investigate early spleen development in the mouse embryo. An expression analysis of early <i>Nkx2.5 </i>expression is reported, along with the finding that <i>Nkx2.5 </i>may be the earliest marker of splenic precursors in the mouse. Expression of <i>Nkx2.5</i> is also shown for the first time to overlap considerably with that of <i>Nkx3.2 </i>– a major gut development gene upstream of <i>Nkx2.5</i>. An <i>in silico </i>analysis of the evolutionary conserved regions upstream of <i>Nkx2.5 </i>is presented along with the establishment and analysis of stable transgenic reporter lines expressing <i>LacZ </i>under the control of an <i>Nkx2.5</i> gut regulatory sequence (<i>NGRS</i>). <i>NGRS </i>confers spleen, posterior stomach, and pyloric sphincter expression, with very little of the cardiac expression associated with endogenous <i>Nkx2.5. </i>This enhancer is thus ideal for gut studies, providing a tool for directing gut-specific expression and genetic manipulations. <i>NGRS </i>was also found not to require <i>Nkx3.2 </i>for its activity. Finally, <i>NGRS </i>is demonstrated to have the potential to mark abnormal spleen development, in a previously unreported splenic mutant: the <i>Rwhs </i>mutant. Potential uses for <i>NGRS </i>are explored. An approach was taken to mark and follow spleen development, using <i>NGRS-LacZ </i>in an organ culture system. Data generated from these experiments shed some light on how the E11.5 spleen develops, providing evidence for migration of splenic precursors along the stomach, and suggesting that an inhibitory “anchor” effect is normally exerted by the posterior spleno-pancreatic mesenchyme, disruption of which permits precocious spleen development. Finally, an analysis of the role of Wnt signalling in development of the spleno-pancreatic region is presented. Wnt signalling is active in the developing spleen at E11.5, E12.5 and E14.5. A number of <i>Wnt </i>and <i>Frz </i>genes are expressed in the E14.5 spleen.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:642243 |
| Date | January 2007 |
| Creators | Burn, Sally |
| Publisher | University of Edinburgh |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://hdl.handle.net/1842/23965 |
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