By exploiting programmable, sequence-dependent base-pairing interactions it is possible to design and build three-dimensional DNA scaffolds, to attach molecular components to them with sub-nanometre precision – and then to make them move. I shall describe our work on autonomous, biomimetic molecular motors powered by chemical fuels, hybrid DNA-kinesin devices, motors that compute, nanostructure assembly, and the use of synthetic molecular machinery to control covalent chemical synthesis.

We imaged the complete brain of a female adult fruit fly at EM resolution. The resulting dataset comprises 21 million images occupying 106 TB. A cluster-backed image processing pipeline was developed to stitch, register, and intensity correct these images, enabling manual tracing of neuronal connectivity throughout the brain. Pilot efforts have focused on the interface between the olfactory system and the mushroom body (MB), the site of associative learning. Each MB contains ~2,000 Kenyon cells (KCs), which receive olfactory input from the antennal lobe via second-order olfactory projection neurons (PNs) in the MB calyx, in what is thought to be a random fashion. KC axons then form a bundle called the pedunculus, which gives rise to the lobes of the mushroom body, where synaptic modulation underlying memory occurs. We traced about 10% of the KCs in the calyx, and their presynaptic PN inputs, to generate a PN-to-KC connectivity graph. We find that KCs that fasciculate with one another in the pedunculus are much more likely to receive input from a common PN, and are also more likely to make axo-axonic synapses with one another. This network structure might be used to sharpen and amplify olfactory signals prior to their arrival in the MB lobes, where synapses are modified during associative Learning.

Bruchpilot (Brp) is a core protein component of the Drosophila active zone (AZ), where it promotes calcium channel clustering to ensure adequate transmitter release. In addition, the C-terminal region of Brp tethers synaptic vesicles to the AZ cytomatrix. In a C-terminally truncated allele, brpnude (lacking the last 17 amino acids), impaired vesicle tethering is accompanied by short-term synaptic depression and impaired sustained transmitter release. We set out to test the hypothesis that neuronal expression of a C-terminal Brp fragment would mimic the synaptic phenotype of brpnude mutants by competitively binding the putative vesicular interaction partner(s) of Brp. Our electrophysiological analysis of larval neuromuscular synapses supports this hypothesis and sets the basis for a subsequent in vivo screen to identify the interacting protein(s). To this end, a membrane-bound C-terminal Brp fragment was neuronally expressed to misdirect synaptic vesicles to ectopic locations. RNAi lines against vesicle-associated proteins were then scored for their ability to revert the ectopic vesicle localisation.