Biology subjects

Giachello, C. N. G.

Publications and source records attributed to Giachello, C. N. G..

5 recordsLinked to original sources

bioRxiv2022

A reductionist paradigm for high-throughput behavioural fingerprinting in Drosophila melanogaster

Understanding how the brain encodes behaviour is the ultimate goal of neuroscience and the ability to objectively and reproducibly describe and quantify behaviour is a necessary milestone on this path. Recent technological progresses in machine learning and computational power have boosted the development and adoption of systems leveraging on high-resolution video recording to track an animal pose and describe behaviour in all four dimensions. However, the high temporal and spatial resolution that these systems offer must come as a compromise with their throughput and accessibility. Here we describe coccinella, an open-source reductionist framework combining high-throughput analysis of behaviour using real-time tracking on a distributed mesh of microcomputers (ethoscopes) with resource-lean statistical learning (HCTSA/Catch22). Coccinella is a reductionist system, yet outperforms state-of-the-art alternatives when exploring the pharmacobehaviour in Drosophila melanogaster.

neuroscience↗

bioRxiv2021

Drosophila nicotinic acetylcholine receptor subunits and their native interactions with insecticidal peptide toxins

Drosophila nicotinic acetylcholine receptors (nAChRs) are ligand-gated ion channels that represent a target for insecticides. Peptide neurotoxins are known to block nAChRs by binding to their target subunits, however, a better understanding of receptor subunit composition is needed for effective design of insecticides. To facilitate the analysis of nAChRs we used a CRISPR/Cas9 strategy to generate null alleles for all ten nAChR subunit genes in a common genetic background. We studied interactions of nAChR subunits with peptide neurotoxins by larval injections and styrene maleic acid lipid particles (SMALPs) pull-down assays. For the null alleles we determined the effects of -Bungarotoxin (-Btx) and {omega}-Hexatoxin-Hv1a (Hv1a) administration, identifying potential receptor subunits implicated in the binding of these toxins. We employed pull-down assays to confirm -Btx interactions with the D5, D6, D7 subunits. Finally, we report the localization of fluorescent tagged endogenous D6 during nervous system development. Taken together this study elucidates native Drosophila nAChR subunit interactions with insecticidal peptide toxins and provides a resource for the in vivo analysis of insect nAChRs.

neuroscience↗

bioRxiv2020

Electrophysiological validation of premotor interneurons monosynaptically connected to the aCC motoneuron in the Drosophila larval CNS.

Mapping the wired connectivity of a nervous system is a prerequisite for full understanding of function. In this respect, such endeavours can be likened to genome sequencing projects. These projects similarly produce impressive amounts of data which, whilst a technical tour-de-force, remain under-utilised without validation. Validation of neuron synaptic connectivity requires electrophysiology which has the necessary temporal and spatial resolution to map synaptic connectivity. However, this technique is not common and requires extensive equipment and training to master, particularly when applied to the small CNS of the Drosophila larva. Thus, validation of connectivity in this CNS has been more reliant on behavioural analyses and, in particular, activity imaging using the calcium-sensor GCaMP. Whilst both techniques are powerful, they each have significant limitations for this purpose. Here we use electrophysiology to validate an array of driver lines reported to label specific premotor interneurons that the Drosophila connectome project suggests are monosynaptically connected to an identified motoneuron termed the anterior corner cell (aCC). Our results validate this proposition for four selected lines. Thus, in addition to validating the connectome with respect to these four premotor interneurons, our study highlights the need to functionally validate driver lines prior to use.

neuroscience↗

bioRxiv2019

Motor circuit function is stabilized during postembryonic growth by anterograde trans-synaptic Jelly Belly - Anaplastic Lymphoma Kinase signaling

The brain adapts to a changing environment or growing body size by structural growth and synaptic plasticity. Mechanisms studied to date promote synaptic growth between partner neurons, while negative counterparts that inhibit such interactions have so far remained elusive. Here, we investigate the role of Jeb-Alk signaling in coordinating motor circuit growth during larval stages of Drosophila. We quantify neuronal growth dynamics by intra-vital imaging, and synaptogenesis at nanometer resolution using endogenously labeled synaptic proteins, conditionally tagged with a fluorophore, and link changes in circuit anatomy with altered synaptic physiology and behavior. We find that loss of Jeb-Alk signaling leads to increased strengthening of synaptic excitation by developmental addition of additional postsynaptic but not pre-synaptic specializations. These changes ultimately lead to an epilepsy-like seizure behavior. We thus demonstrate that trans-synaptic anterograde Jeb-Alk signaling acts to stabilize developmental plasticity and circuit function, and that it does so specifically during postembryonic growth.

neuroscience↗

bioRxiv2019

Activity manipulation of an excitatory interneuron, during an embryonic critical period, alters network tuning of the Drosophila larval locomotor circuit

As nervous systems develop, activity perturbations during critical periods can lead to permanently altered network function. However, how activity perturbation influences individual synapses, the network response and the underlying signalling mechanisms are not well understood. Here, we exploit a recently identified critical period in the development of the Drosophila larval locomotor circuit to show that activity perturbation differentially affects individual and identified synaptic pairings. Remarkably, we further show that activity-manipulation of a selective excitatory interneuron is sufficient to fully recapitulate the effects induced by network-wide activity disturbance; indicative that some neurons make a greater contribution to network tuning. We identify nitric oxide (NO)-signalling as a potential mediator of activity-dependent network tuning during the critical period. Significantly, the effect of NO-signalling to network tuning is dictated by the prior activity state of the network. Thus, this study provides mechanistic insight that is currently lacking into how activity during a critical period tunes a developing network.

neuroscience↗