2009 Undergraduate Poster Award

Congratulations!

The first prize is a one week trip to Germany, visiting selected neuroscience hot spots. This year, yet another undergrad from Bates College, Maine, of Nancy Kleckner’s lab carried away the trophy: Miranda Gallo. Here to the left , with Lutz Steiner of Medical Neurosciences, Berlin awarding the winning certificate.

Miranda’s complex and thorough research project on the central pattern generator of the pond snail (Helisoma trivolvis) and her professional presentation convinced the jurors unanimously. On the jury sat Prof. Dr. Horst Herbert of Tübingen, Prof. Dr. Josef Priller of Berlin, Dr. Erich Schneider of Munich and Dr. Felipe Opazo of Göttingen.

Runners-up were Adam Bledsoe of the University of South Dakota and Natasha Meyer of Davidson College. The prizes were awarded the same evening. A large and lively audience of undergrads and faculty watched the award ceremony during the FUN Social in Chicago on 19 October, hosted by FUN president Jennifer Yates and past president Christopher Korey.

Information on the Winning Poster

Author: M. Gallo and N.W. Kleckner, Bates College, Lewiston, ME

Title: Characterization of a novel α-GluR5/6/7-immunoreactive cell group in the buccal ganglia of the pond snail, Helisoma trivolvis.

Abstract:
A modifiable central pattern generator (CPG) composed of neurons divided into three distinct subunits controls the three-part motor feeding behavior of Helisoma trivolvis. The subunits S1, S2, and S3 correspond to protraction, retraction, and hyperretraction, respectively, of the dentated radula. The subunits interact as independent conditional oscillators, becoming active when released from inhibition or when directly stimulated, and thus producing a cyclic feeding pattern. Glutamate is known to pattern the CPG through inhibition of phase 1 and 3 during excitation of S2. This indicates that distinct glutamate receptors must be present to provide for the divergent responses to glutamate. Glutamate receptor antibodies provide a method to assess which glutamate receptors are present in the network. Probing with an antibody that recognizes α-GluR5/6/7 subunits revealed cells whose involvement with the feeding circuitry has not yet been characterized. The goal of this study is to characterize these α-GluR5/6/7 immunoreactive (IR) cells with respect to physiology, pharmacology, and involvement with the feeding CPG. Serendipitously it was discovered that there is extensive doublelabeling of α-GluR5/6/7 and an antibody made against Lymnaea stagnalis neuropeptide phenylalanine (NPF), the invertebrate homolog of neuropeptide tyrosine (NPY). This suggests that α-GluR5/6/7 IR cells should release NPF when stimulated to fire. Simultaneous electrophysiological recordings were made from cells within the α-GluR5/6/7 IR group to characterize their pharmacology and involvement with the CPG. Targeting accuracy was ensured by iontophoretic injection of Neurobiotin in the targeted cell and co-processing for the α-GluR5/6/7 antibody. α-GluR5/6/7 IR cell morphologies resemble that of the buccal A cluster (BAC) cells. GluR5/6/7 IR cells were depolarized by kainate but insensitive to glutamate and quisqualate. α-GluR5/6/7 IR cells generate sub-threshold slow excitatory post-synaptic potentials (GR EPSPs). Activity in α-GluR5/6/7 IR cells corresponds with excitation of S2 motor neurons and, logically, S2- stimulated hyperpolarizations of S3 motor neurons. A similar pattern of activity, interestingly stimulated by application of NPF, is seen in BAC cells and serves to shut down phase 3 of feeding. That BAC neurons and α-GluR5/6/7 IR cells share similar phsyiology, morphology, and potential signaling molecule suggests that the two networks are connected. These data suggest that the possible modulatory role of α-GluR5/6/7 IR neurons in the feeding CPG converges with the satiation/regurgitation behaviors initiated by the BAC neuron firing.

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