EGFR signaling regulates synaptic connectivity via Gurken

The synapse is the essential unit of neural function. It is critical to understand how synapses form during development, how they are maintained throughout the life of an organism, and how their structure and function are affected by neural activity. An understanding of these aspects of synapses will likely provide insight into the etiology of neurodevelopmental disorders such as autism, mental retardation or epilepsy. To identify novel regulators of synaptic development, I screened for mutants with defects in synaptic morphology and growth at the Drosophila larval neuromuscular junction: NMJ). My screen identified several mutants with defects in various aspects of synaptic development. I pursued a more in depth analysis of an identified mutant, happyhour, with defects in synaptic target selection. Synaptic target selection is critical for establishing functional neuronal circuits. The mechanisms regulating target selection remain incompletely understood. I describe a role for the EGF receptor and its ligand Gurken in target selection of octopaminergic Type II neurons in the Drosophila neuromuscular system. Mutants in happyhour, a regulator of EGFR signaling, form ectopic Type II neuromuscular junctions. These ectopic innervations are due to inappropriate target selection. I demonstrate that EGFR signaling is necessary and sufficient to inhibit synaptic target selection by these octopaminergic Type II neurons, and that the EGFR ligand Gurken is the post-synaptic, muscle-derived repulsive cue. These results identify a new pathway mediating cell-type and branch-specific synaptic repulsion, a novel role for EGFR signaling in synaptic target selection, and an unexpected role for Gurken as a muscle-secreted repulsive ligand

EGFR signaling regulates synaptic connectivity via Gurken

The synapse is the essential unit of neural function. It is critical to understand how synapses form during development, how they are maintained throughout the life of an organism, and how their structure and function are affected by neural activity. An understanding of these aspects of synapses will likely provide insight into the etiology of neurodevelopmental disorders such as autism, mental retardation or epilepsy. To identify novel regulators of synaptic development, I screened for mutants with defects in synaptic morphology and growth at the Drosophila larval neuromuscular junction: NMJ). My screen identified several mutants with defects in various aspects of synaptic development. I pursued a more in depth analysis of an identified mutant, happyhour, with defects in synaptic target selection. Synaptic target selection is critical for establishing functional neuronal circuits. The mechanisms regulating target selection remain incompletely understood. I describe a role for the EGF receptor and its ligand Gurken in target selection of octopaminergic Type II neurons in the Drosophila neuromuscular system. Mutants in happyhour, a regulator of EGFR signaling, form ectopic Type II neuromuscular junctions. These ectopic innervations are due to inappropriate target selection. I demonstrate that EGFR signaling is necessary and sufficient to inhibit synaptic target selection by these octopaminergic Type II neurons, and that the EGFR ligand Gurken is the post-synaptic, muscle-derived repulsive cue. These results identify a new pathway mediating cell-type and branch-specific synaptic repulsion, a novel role for EGFR signaling in synaptic target selection, and an unexpected role for Gurken as a muscle-secreted repulsive ligand

Enhancing Memory Through Literary Features

Literary devices used by a writer can influence and impact the manner in which readers respond and interact with a text. Both the perspectives readers are expected to take while reading and the amount of foregrounding in a text cognitively and affectively influence a reader’s experience. However, little research has explored what effects these factors have on verbatim memory. For this research, participants were instructed to read a short literary story either by identifying with the protagonist or as a spectator. After reading and completing a range of other tasks, participants were asked to select sentences they saw in the story verbatim. This research found there was a significant increase in memory for literary sentences compared to non-literary sentences, but no significant difference in memory between the two perspective conditions

Evaluating interprofessional simulation in the operating theatre

The operating theatre is an area of practice that newly qualified Diagnostic Radiographers find challenging. Interprofessional education (IPE) and simulation are becoming widely used in healthcare education in order to prepare students for practice. Failures in interprofessional communication are well-documented with poor communication an established cause of medical error and negative health outcomes. Socio-historical issues like imbalances in power and status are particularly prevalent in the operating theatre environment, and add complications to interprofessional working. As part of an action research study to develop and pilot an interprofessional simulation experience for Operating Department Practitioner (ODP) and Diagnostic Radiography (DRAD) students. Diagnostic Radiography students took part in a simulation in the mock operating theatre on the university campus with an ODP student, ODP and Diagnostic Radiography lecturers. A purposive convenience sample of 48 second year Diagnostic Radiography students participated in the simulation. Following the simulation students were asked to evaluate the session using Padlet and later reflect on the impact of the experience on practice. The simulation was a positive experience. The timing and organisation of the simulation is important for the students to get the most out of the experience. There are benefits of being immersed in a high fidelity simulation and the realism plays a role in preparing students for real life experiences

Breast compression techniques in screening mammography – A Maltese evaluation project

Introduction: In screening mammography, the radiographer should be responsible for providing mammograms of high diagnostic value, possibly without subjecting clients to a painful experience. This skill is demonstrated via the technique of breast compression and is explored in this study by analysing insights about methods and underlying principles in regards to this procedure. Methods: One-to-one semi-structured interviews were conducted with radiographers who perform screening mammography in Malta. For data analysis, a descriptive phenomenological approach following a simplified version of Hycner's (1985) method was adopted. Results: Five general themes were extracted from the data; meeting the client, preparing the client, the mammography procedure, pain from compression and client turnout. It was determined that the participants alter their breast compression technique according to the client rather than following a rigid step-by-step process and that explanation and requesting client feedback are essential to obtain cooperation. Additionally, mammography positioning and compression application are tailored in a way that encourage compliance, however not at the expense of degrading image quality. Ultimately, it is also believed that a proper breast compression technique positively influences client turnout. Conclusion: The results of this study demonstrate that radiographers should be flexible in their approach in order to carry out a successful breast compression technique. However, it has also been shown that such effectiveness in practice is gained from experience rather than initial training. If exposed to this study's findings, new mammographers would be able to form a robust core of knowledge before embarking on the challenging specialisation of mammography

A model of toxic neuropathy in Drosophila reveals a role for MORN4 in promoting axonal degeneration

Axonal degeneration is a molecular self-destruction cascade initiated following traumatic, toxic, and metabolic insults. Its mechanism underlies a number of disorders including hereditary and diabetic neuropathies and the neurotoxic side effects of chemotherapy drugs. Molecules that promote axonal degeneration could represent potential targets for therapy. To identify such molecules, we designed a screening platform based on intoxication of Drosophila larvae with paclitaxel (taxol), a chemotherapeutic agent that causes neuropathy in cancer patients. In Drosophila, taxol treatment causes swelling, fragmentation, and loss of axons in larval peripheral nerves. This axonal loss is not due to apoptosis of neurons. Taxol-induced axonal degeneration in Drosophila shares molecular execution mechanisms with vertebrates, including inhibition by both NMNAT (nicotinamide mononucleotide adenylyltransferase) expression and loss of wallenda/DLK (dual leucine zipper kinase). In a pilot RNAi-based screen we found that knockdown of retinophilin (rtp), which encodes a MORN (membrane occupation and recognition nexus) repeat-containing protein, protects axons from degeneration in the presence of taxol. Loss-of-function mutants of rtp replicate this axonal protection. Knockdown of rtp also delays axonal degeneration in severed olfactory axons. We demonstrate that the mouse ortholog of rtp, MORN4, promotes axonal degeneration in mouse sensory axons following axotomy, illustrating conservation of function. Hence, this new model can identify evolutionarily conserved genes that promote axonal degeneration, and so could identify candidate therapeutic targets for a wide-range of axonopathies

Non-classical photon streams using rephased amplified spontaneous emission

We present a fully quantum mechanical treatment of optically rephased photon echoes. These echoes exhibit noise due to amplified spontaneous emission, however this noise can be seen as a consequence of the entanglement between the atoms and the output light. With a rephasing pulse one can get an "echo" of the amplified spontaneous emission, leading to light with nonclassical correlations at points separated in time, which is of interest in the context of building wide bandwidth quantum repeaters. We also suggest a wideband version of DLCZ protocol based on the same ideas.Comment: 5 pages, 4 figures. Added section

VISIBILITY AND USAGE OF ISBS PROCEEDINGS AT FORTY YEARS

This study described the visibility and usage of research published in ISBS conference proceedings articles from 1983 to 2022. The 6,688 articles were downloaded 1,955,728 times in total, and 78% were indexed by Google Scholar. In recent proceedings, the number of articles and total downloads have decreased but downloads per article per year of availability have increased steeply. Top (1%) cited articles in Google Scholar had citations and citation rates similar to articles in biomechanics journals. While visibility has grown, there is limited citation of most ISBS proceedings articles compared to journal articles

Stochastic dynamics in periodic potentials

This thesis describes the dynamics of both electrons and atoms in periodic potentials. In particular, it explores how such potentials can be used to realise a new type of quantum chaos in which the effective classical Hamiltonian originates from the intrinsically quantum nature of energy bands. Firstly, this study examines electron dynamics in a superlattice with an applied voltage and a tilted magnetic field. This system displays a rare type of chaos known as non-KAM (Kolmogorov-Arnold-Moser) chaos, which switches on abruptly when an applied perturbation reaches certain critical values. The onset of chaos in the system leads to the formation of complex patterns in phase space known as stochastic webs. The electron behaviour under these conditions is analysed both semiclassically and quantum mechanically, and the results compared to experimental studies. We show that the presence of stochastic webs strongly enhances electron transport. We calculate Wigner functions of the electron wavefunction at various times and show that, when compared to the Poincare sections, evidence of stochastic web formation is observed in the quantum mechanical phase space. Two designs of superlattice are studied and we show, in a full quantum mechanical analysis, that the design of the superlattice has a pronounced effect on the probability of inter-miniband tunnelling and hence the calculated and measured transport characteristics. Secondly, we explore the dynamics of an ultra-cold sodium atom falling through an optical lattice whilst confined in a harmonic gutter potential that is tilted at an angle to the lattice axis. We show this system is analogous to the case of an electron in a superlattice, and that the atomic dynamics show similar enhanced transport properties for certain trapping frequencies. We also find that in a full quantum mechanical calculation, the atomic wavepacket tends to fragment as the angle at which the gutter potential is tilted is increased. Finally, we examine the dynamics of a Bose-Einstein condensate falling through an optical lattice whilst confined in a harmonic gutter potential. We vary the strength of the interatomic interaction parameter to investigate the role of interactions in the system and find that, even for small tilt angles, the condensate wavefunction fragments. For large interaction parameters combined with large tilt angles, the wavefunction explodes catastrophically