A Large-Scale Behavioral Screen to Identify Neurons Controlling Motor Programs in the Drosophila Brain

Drosophila is increasingly used for understanding the neural basis of behavior through genetically targeted manipulation of specific neurons. The primary approach in this regard has relied on the suppression of neuronal activity. Here, we report the results of a novel approach to find and characterize neural circuits by expressing neuronal activators to stimulate subsets of neurons to induce behavior. Classical electrophysiological studies demonstrated that stimulation of command neurons could activate neural circuits to trigger fixed action patterns. Our method was designed to find such command neurons for diverse behaviors by screening flies in which random subsets of brain cells were activated. We took advantage of the large collection of Gal4 lines from the NP project and crossed 835 Gal4 strains with relatively limited Gal4 expression in the brain to flies carrying a UAS transgene encoding TRPM8, a cold-sensitive ion channel. Low temperatures opened the TRPM8 channel in Gal4-expressing cells, leading to their excitation, and in many cases induced overt behavioral changes in adult flies. Paralysis was reproducibly observed in the progeny of crosses with 84 lines, whereas more specific behaviors were induced with 24 other lines. Stimulation performed using the heat-activated channel, TrpA1, resulted in clearer and more robust behaviors, including flight, feeding, and egg-laying. Through follow-up studies starting from this screen, we expect to find key components of the neural circuits underlying specific behaviors, thus providing a new avenue for their functional analysis.National Institute of Mental Health (U.S.) (Grant MH85958)Worcester Foundation for Biomedical ResearchJapan Society for the Promotion of Science (grant-in-aid)National Institute of Mental Health (U.S.) (Intramural Research Program

Synaptic targeting and localization of Discs-large is a stepwise process controlled by different domains of the protein

AbstractBackground: Membrane-associated guanylate kinases (MAGUKs) assemble ion channels, cell-adhesion molecules and components of second messenger cascades into synapses, and are therefore potentially important for co-ordinating synaptic strength and structure. Here, we have examined the targeting of the Drosophila MAGUK Discs-large (DLG) to larval neuromuscular junctions.Results: During development, DLG was first found associated with the muscle subcortical compartment and plasma membrane, and later was recruited to the postsynaptic membrane. Using a transgenic approach, we studied how mutations in various domains of the DLGprotein affect DLG targeting. Deletion of the HOOKregion—the region between the Src homology 3 (SH3) domain and the guanylate-kinase-like (GUK) domain—prevented association of DLG with the subcortical network and rendered the protein largely diffuse. Loss of the first two PDZ domains led to the formation of large clusters throughout the plasma membrane, with scant targeting to the neuromuscular junction. Proper trafficking of DLG missing the GUK domain depended on the presence of endogenous DLG.Conclusions: Postsynaptic targeting of DLG requires a HOOK-dependent association with extrasynaptic compartments, and interactions mediated by the first two PDZ domains. The GUK domain routes DLG between compartments, possibly by interacting with recently identified cytoskeletal-binding partners

Synaptic targeting and localization of Discs-large is a stepwise process controlled by different domains of the protein

AbstractBackground: Membrane-associated guanylate kinases (MAGUKs) assemble ion channels, cell-adhesion molecules and components of second messenger cascades into synapses, and are therefore potentially important for co-ordinating synaptic strength and structure. Here, we have examined the targeting of the Drosophila MAGUK Discs-large (DLG) to larval neuromuscular junctions.Results: During development, DLG was first found associated with the muscle subcortical compartment and plasma membrane, and later was recruited to the postsynaptic membrane. Using a transgenic approach, we studied how mutations in various domains of the DLGprotein affect DLG targeting. Deletion of the HOOKregion—the region between the Src homology 3 (SH3) domain and the guanylate-kinase-like (GUK) domain—prevented association of DLG with the subcortical network and rendered the protein largely diffuse. Loss of the first two PDZ domains led to the formation of large clusters throughout the plasma membrane, with scant targeting to the neuromuscular junction. Proper trafficking of DLG missing the GUK domain depended on the presence of endogenous DLG.Conclusions: Postsynaptic targeting of DLG requires a HOOK-dependent association with extrasynaptic compartments, and interactions mediated by the first two PDZ domains. The GUK domain routes DLG between compartments, possibly by interacting with recently identified cytoskeletal-binding partners

Inner-shell photodetachment of na-using r-matrix methods

Inner-shell photodetachment of Na-near the L-edge threshold was investigated using the R-matrix method. Significant structure was found in the cross section, and this structure is shown to be related to the complicated correlated electron dynamics endemic in negative ions. Comparison with experiment suggests that the absolute values of the measured cross section might be too small by a factor of two. © 2020 by the authors

Postsynaptic membrane addition depends on the Discs-Large-interacting t-SNARE Gtaxin

Targeted membrane addition is a hallmark of many cellular functions. In the nervous system, modification of synaptic membrane size has a major impact on synaptic function. However, because of the complex shape of neurons and the need to target membrane addition to very small and polarized synaptic compartments, this process is poorly understood. Here, we show that Gtaxin (GTX), a Drosophila t-SNARE (target-soluble N-ethylmaleimide-sensitive factor attachment protein receptor), is required for expansion of postsynaptic membranes during new synapse formation. Mutations in gtx lead to drastic reductions in postsynaptic membrane surface, whereas gtx upregulation results in the formation of complex membrane structures at ectopic sites. Postsynaptic GTX activity depends on its direct interaction with Discs-Large (DLG), a multidomain scaffolding protein of the PSD-95 (postsynaptic density protein-95) family with key roles in cell polarity and formation of cellular junctions as well as synaptic protein anchoring and trafficking. We show that DLG selectively determines the postsynaptic distribution of GTX to type I, but not to type II or type III boutons on the same cell, thereby defining sites of membrane addition to this unique set of glutamatergic synapses. We provide a mechanistic explanation for selective targeted membrane expansion at specific synaptic junctions

Thermotunneling Based Cooling Systems for High Efficiency Buildings

GE Global Research's overall objective was to develop a novel thermotunneling-cooling device. The end use for these devices is the replacement of vapor cycle compression (VCC) units in residential and commercial cooling and refrigeration systems. Thermotunneling devices offer many advantages over vapor cycle compression cooling units. These include quiet, reliable, non-moving parts operation without refrigerant gases. Additionally theoretical calculations suggest that the efficiency of thermotunneling devices can be 1.5-2x that of VCC units. Given these attributes it can be seen that thermotunneling devices have the potential for dramatic energy savings and are environmentally friendly. A thermotunneling device consists of two low work function electrodes separated by a sub 10 nanometer-sized gap. Cooling by thermotunneling refers to the transport of hot electrons across the gap, from the object to be cooled (cathode) to the heat rejection electrode (anode), by an applied potential. GE Global Research's goal was to model, design, fabricate devices and demonstrate cooling base on the thermotunneling technology

Perspectives on Astrophysics Based on Atomic, Molecular, and Optical (AMO) Techniques

About two generations ago, a large part of AMO science was dominated by experimental high energy collision studies and perturbative theoretical methods. Since then, AMO science has undergone a transition and is now dominated by quantum, ultracold, and ultrafast studies. But in the process, the field has passed over the complexity that lies between these two extremes. Most of the Universe resides in this intermediate region. We put forward that the next frontier for AMO science is to explore the AMO complexity that describes most of the Cosmos.Comment: White paper submission to the Decadal Assessment and Outlook Report on Atomic, Molecular, and Optical (AMO) Science (AMO 2020