Investigating the molecular mechanisms involved in the developmental assembly of the mushroom body calyx in <em>Drosophila melanogaster</em>

Abstract

How a circuit functions can be investigated by examining the organisation of the circuit to be able to decipher the connectivity logic and the logic of information flow within that circuit. Hence, to understand how the sparse coding of the Kenyon cells (KCs) is wired into the circuit, the organisational logic must be resolved. To that effect, a major question emerges - how do KCs find their synaptic partners during development?<br /> This thesis aims to answer that question by taking advantage of available transcriptomic datasets (Alyagor et al. 2018; Li et al. 2020; Li et al. 2017; Xie et al. 2021) and focusing on the possible role of cell surface molecules in circuit assembly by means of RNAi-mediated knockdown in the PNs and KC. The effect of the knockdown was analysed by measuring number and distribution of PN boutons, calyx organisation and synapse formation. Based on this primary RNAi screen, candidate molecules that displayed circuit defects in the calyx were isolated and examined for the pattern of expression, the mutant phenotype and its cell autonomy in order to elucidate the role the molecules play in the development of the calyx. In addition, a method for in vivo imaging of the pupa was developed to be able to image developmental milestones in the context of normal development as well as mutants.<br /> With this work, we hope to shed light in understanding how the non-stereotypical circuit of the calyx is assembled during development.