Title: The subnuclear localisation of Notch responsive genes. Candidate Name: Matthew Jones Notch signalling is a highly conserved cell-cell communication pathway with critical roles in metazoan development and mutations in Notch pathway components are implicated in many types of cancer. Notch is an excellent and well-studied model of biological signalling and gene regulation, with a single intracellular messenger, one receptor and two ligands in Drosophila. However, despite the limited number of chemical players involved, a striking number of different outcomes arise. Molecular studies have shown that Notch activates different targets in different cell types and it is well known that Notch is important for maintaining a stem cell fate in some situations and driving differentiation in others. Thus some of the factors affecting the regulation of Notch target genes are yet to be discovered. Previous studies in various organisms have found that the location of a gene within the nucleus is important for its regulation and genome reorganisation can occur following gene activation or during development. Therefore this project aimed to label individual Notch responsive loci and determine their subnuclear localisation. In order to tag loci of interest a CRISPR/Cas9 genome-editing method was established that enabled the insertion of locus tags at Notch targets, namely the well-characterized Enhancer of split locus and also dpn and Hey, two transcription factors involved in neural cell fate decisions. The ParB/Int system is a recently developed locus tagging system and is not well characterised in Drosophila. It has a number of advantages over the traditional LacO/LacI-GFP locus tagging system as it does not rely on binding site repeats for signal amplification and can label two loci simultaneously in different colours. This thesis characterised the ParB/Int system in the Drosophila salivary gland and larval L3 neuroblast. Using 3D image segmentation hundreds of nuclei were reconstructed and a volume based normalisation method was applied to determine the subnuclear localisation of several Notch targets with and without genetic manipulations of the Notch pathway.