1. Making Fly Synapses with and without Glutamate Receptors
Andreas Schmid, Gang Qin, Carolin Wichmann, Robert J. Kittel, Sara Mertel, Wernher Fouquet, Manuela Schmidt, Manfred Heckmann, and Stephan J. Sigrist
A small army of structural proteins is needed to cluster and anchor postsynaptic receptors, ion channels, and other molecules to the right spots at synapses. This week, Schmid et al. report that non- NMDA glutamate receptors are key players in this process at the Drosophila neuromuscular junction. The authors genetically manipulated flies so that they produced a few or no postsynaptic glutamate receptors. Whereas the mutant animals formed neuromuscular junctions with fairly normal presynaptic active zones, the postsynaptic density never achieved normal size or an appropriate disposition of postsynaptic molecules. The organization of the postsynaptic structure did not appear to depend on glutamate binding or ion flux, because larvae whose synaptic activity was blocked formed normal-sized synapses. The results argue for a structural role of glutamate receptors in the protein protein interactions that lead to maturation and assembly of the fly neuromuscular junction.
2. Sensory Input and Olfactory Bulb Circuits
Carolyn A. Marks, Kai Cheng, Diana M. Cummings, and Leonardo Belluscio
Noses come in all shapes and sizes, but the internal wiring is remarkably consistent across species. Axons of neurons expressing the same odorant receptor typically converge onto a pair of glomeruli on the surface of each olfactory bulb. Glomerular pairs, sharing the same functional properties, are then linked through a set of reciprocal intrabulbar projections to form a spatially conserved map. This week, Marks et al. sought to determine how this intrabulbar map develops. They injected dye into small areas of the olfactory bulb of mice and examined the resulting projections. Whereas in adults, the size of the tracer injection
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Society for Neuroscience