a-single-fly-assay-for-foraging-behavior-in-drosophila

A Single-fly Assay for Foraging Behavior in <em>Drosophila</em>

For many animals, hunger promotes changes in the olfactory system in a manner that facilitates the search for appropriate food sources. In this video ...

University of California-San Diego

Retrograde signals influence neuronal survival, differentiation, synaptogenesis, and plasticity. Several recent papers describe novel roles for the well-studied TGF-beta pathway in retrograde synaptic signaling. While each dissects spatial and molecular aspects of TGF-beta signaling in a specific synaptic context, together these studies demonstrate that a specific retrograde signal may be interpreted in diverse, neuron-specific ways. Thus, a neuron's intrinsic properties and its other extrinsic signaling inputs determine its cellular and genomic response to TGF-beta.

Retrograde regulation in the CNS; neuron-specific interpretations of TGF-beta signaling.

Sensory identity usually remains constant across a large intensity range. Vertebrates use lateral inhibition to match the sensitivity of retinal ganglion cells to the intensity of light. A new study published in Journal of Biology suggests that lateral inhibition in the Drosophila antennal lobe is similarly required for concentration-invariant perception of odors.

Lateral inhibition and concentration-invariant odor perception.

In all nervous systems, short-term enhancement of transmitter release is achieved by increasing the weights of unitary synapses; in contrast, long-term enhancement, which requires nuclear gene expression, is generally thought to be mediated by the addition of new synaptic vesicle release sites. In Drosophila motor neurons, induction of AP-1, a heterodimer of Fos and Jun, induces cAMP- and CREB-dependent forms of presynaptic enhancement. Light and electron microscopic studies indicate that this synaptic enhancement is caused by increasing the weight of unitary synapses and not through the insertion of additional release sites. Electrophysiological and optical measurements of vesicle dynamics demonstrate that enhanced neurotransmitter release is accompanied by an increase in the actively cycling synaptic vesicle pool at the expense of the reserve pool. Finally, the observation that AP-1 mediated enhancement eliminates tetanus-induced forms of presynaptic potentiation suggests: (i) that reserve-pool mobilization is required for tetanus-induced short-term synaptic plasticity; and (ii) that long-term synaptic plasticity may, in some instances, be accomplished by stable recruitment of mechanisms that normally underlie short-term synaptic change.

Fos and Jun potentiate individual release sites and mobilize the reserve synaptic vesicle pool at the Drosophila larval motor synapse.

In this work we present how to entirely remove the scattering ambiguity present in existing multiphoton multifocal systems. This is achieved through the development and implementation of single-element detection systems that incorporate high-speed photon-counting electronics. These systems can be used to image entire volumes in the time it takes to perform a single transverse scan (four depths simultaneously at a rate of 30 Hz). In addition, this capability is further exploited to accomplish single-element detection of multiple modalities (two photon excited fluorescence and second harmonic generation) and to perform efficient image deconvolution. Finally, we demonstrate a new system that promises to significantly simplify this promising technology.

Eliminating the scattering ambiguity in multifocal, multimodal, multiphoton imaging systems.

After Drosophila males are rejected by mated females, their subsequent courtship is inhibited even when encountering virgin females. Molecular mechanisms underlying courtship conditioning in the CNS are unclear. In this study, we find that tyramine β hydroxylase (TβH) mutant males unable to synthesize octopamine (OA) showed impaired courtship conditioning, which could be rescued by transgenic TβH expression in the CNS. Inactivation of octopaminergic neurons mimicked the TβH mutant phenotype. Transient activation of octopaminergic neurons in males not only decreased their courtship of virgin females, but also produced courtship conditioning. Single cell analysis revealed projection of octopaminergic neurons to the mushroom bodies. Deletion of the OAMB gene encoding an OA receptor expressed in the mushroom bodies disrupted courtship conditioning. Inactivation of neurons expressing OAMB also eliminated courtship conditioning. OAMB neurons responded robustly to male-specific pheromone cis-vaccenyl acetate in a dose-dependent manner. Our results indicate that OA plays an important role in courtship conditioning through its OAMB receptor expressed in a specific neuronal subset of the mushroom bodies.

Molecular genetic analysis of sexual rejection: roles of octopamine and its receptor OAMB in Drosophila courtship conditioning.

Calcium imaging is a powerful technique that permits the visual monitoring of neural responses to pheromones and other odors in large ensembles of neurons. Here, we describe a method that permits the monitoring of Drosophila antennal lobe responses to odors using the genetically encoded calcium monitor GCaMP.

Article	Year
Retrograde regulation in the CNS; neuron-specific interpretations of TGF-beta signaling. Neuron\| PubMed ID: 15046717	2004
Lateral inhibition and concentration-invariant odor perception. Journal of biology\| PubMed ID: 19216732	2009
Fos and Jun potentiate individual release sites and mobilize the reserve synaptic vesicle pool at the Drosophila larval motor synapse. Proceedings of the National Academy of Sciences of the United States of America\| PubMed ID: 19228945	2009
Eliminating the scattering ambiguity in multifocal, multimodal, multiphoton imaging systems. Journal of biophotonics\| PubMed ID: 22461190	2012
Molecular genetic analysis of sexual rejection: roles of octopamine and its receptor OAMB in Drosophila courtship conditioning. The Journal of neuroscience : the official journal of the Society for Neuroscience\| PubMed ID: 23055498	2012
Calcium imaging of pheromone responses in the insect antennal lobe. Methods in molecular biology (Clifton, N.J.)\| PubMed ID: 24014361	2013

Susy M. Kim

Biography

JoVE Journal Publications

Other Publications