Page 307 - 53rd Annual Drosophila Research Conference

Poster Full Abstracts - Neurophysiology and Behavior
Poster board number is above title. The first author is the presenter
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modification of phototransduction genes, implying differences in the usage and organization of visual genes in other insects. We have therefore begun to
explore the molecular organization of photoresponse in the simple visual system of the red flour beetle Tribolium castaneum . Comparing the adult head
transcriptome of wild-type and eye-depleted animals, we identified over 1000 retinal candidate genes. These include validation genes previously
characterized in Tribolium (opsins, cinnabar and glass ) but also candidate validation genes based on presumed evolutionary conservation of Tribolium with
Drosophila (Pph13, chaoptin, white and many members of the phototransduction network). However, approximately 95% of the Tribolium retinal candidate
genes have so far not yet been associated with vision related gene ontologies. These loci are now being investigated by whole mount in situ hybdridization
and gene knockdown, testing for photoreceptor-specific expression and possible effects on the photonegative behavior of the Tribolium larva. Interestingly,
homolog analysis revealed that 54 of the Tribolium candidate genes are shared with vertebrates, but absent in Drosophila.
651C
The Prion Protein Binds to Synapsin and Syntaxin in the Presynaptic Neuromuscular Junction. Jose E Herrera1,2, Diego Rincon-Limas 2, Pedro
Fernandez-Funez 2,3. 1) éMaster's Program in Translational Biotechnology, University of Florida, Gainesville, FL; 2) Neurology, University of Florida,
Gainesville, FL; 3) Neuroscience, University of Florida, Gainesville, FL.
The prion protein (PrP) is a GPI-anchored glycoprotein located in the extracellular membrane of neuronal and glial cells of the developing and mature
nervous system. Although PrP misfolding and aggregation are the causative factors in several neurodegenerative disorders, the physiological role of PrP is
unknown. Previous studies have described the localization of PrP in the synapse, where it interacts with synaptic proteins; however, the physiological
relevance thereof remains unknown. Thus, my goal is to ascertain the function of PrP in the synapse, based on its interaction with known synaptic proteins.
Using transgenic flies that express wild-type PrP, I first tested the co-localization of PrP with candidate synaptic proteins by immunofluorescence. Then, I
utilized co-immunoprecipitation to confirm the direct interaction of positive candidates. I found that the presynaptic proteins, Synapsin and Syntaxin, co-
localize and interact directly with the wild-type PrP, suggesting a role in neurotransmission for PrP. Moreover, I studied two mutant PrP fly strains, M206,
213S and Y145stop, to characterize phenotypic changes in synaptic morphology and protein distribution. The distribution of Syntaxin also changed in flies
expressing PrP-M206, 213S, as did the number and size of synaptic boutons. To further elucidate its role in the synapse, I plan to use a proteomics approach
involving synaptosomal separation, co-immunoprecipitation, and mass spectrometry, which will provide a more unbiased, complete list of binding partners
for PrP. A comprehensive identification of all the PrP-binding proteins at the synapse will allow us to better understand the role of PrP in synapse function
and/or architecture.
652A
Myosin VI contributes to synaptic transmission and development at the Drosophila neuromuscular junction. Marta Kisiel1, Bryan Stewart1,2 . 1) Cell
and System Biology, University of Toronto, Toronto, Canada; 2) Department of Biology, University of Toronto Mississauga, Mississauga, Canada.
Myosin VI, encoded by jaguar (jar) in Drosophila melanogaster, is the only member of the myosin superfamily of actin-based motor proteins known to
move towards the minus ends of actin filaments. In vitro studies demonstrate that Myosin VI has the ability to perform distinct functions as a cargo
transporter and anchor in the cell, however which of these roles Myosin VI plays in the nervous system has yet to be determined. A locomotor defect,
observed as sluggish movement in severe jar mutant larvae, was confirmed by behavioural assays. As this can indicate problems at the neuromuscular
synapse, microscopy and electrophysiology were used to investigate neuromuscular junction (NMJ) structure and function in jar loss of function mutants of
varying severity. Confocal imaging studies revealed a decrease in NMJ length, a reduction in bouton number per NMJ and mislocalization of synaptotagmin
in jar mutant boutons. Electrophysiological experiments revealed a role for Myosin VI in basal synaptic transmission, with a reduction in low frequency
nerve-evoked responses and spontaneous release in severe jar mutants. Changes in short-term synaptic plasticity were also observed in Myosin VI mutants
using high frequency stimulation paradigms to recruit vesicles from different functional pools. In addition, a decrease in the number of active zones, which
are the sites of vesicle release, was observed by staining against Bruchpilot at jar mutant synapses. As Bruchpilot loss of function is associated with a
reduction in evoked nerve response, this is consistent with impaired synaptic function in jar mutants. Taken together, the data suggest that Myosin VI may
function as an anchor to maintain proper peripheral vesicle localization at the bouton. Accompanied by the reduction in active zones, vesicles could be
displaced from areas of higher probability release at jar mutant synapses. This study aims to elucidate the mechanism of Myosin VI function in neural
communication.
653B
Rugose, a Drosophila homologue of the mammalian Neurobeachin, is involved in larval locomotion, adult habituation, learning and activity
patterns. Emma Schatoff1 , Julian Flores1 , Alexandria Wise2 , Tadmiri Venkatesh 1. 1) Biology, City University of New York The City College, New York,
NY; 2) The Graduate Center, City University of New York, New York, NY.
Rugose is the Drosophila homologue of the mammalian and human Neurobeachin. Recent studies have shown that the Neurobeachin gene is disrupted in
human patients with idiopathic Autism (Castermans et al., 2003) and the Neurobeachin gene spans the common Fragile site FRA 13A (Savelyeva et al.,
2006). Our previous genetic and molecular analyses have shown that rugose (rg) encodes a Drosophila A kinase anchor protein (DAKAP 550) which
interacts with the components of the EGFR- and Notch-mediated signaling pathways and facilitates cross-talk between multiple signaling pathways
(Shamloulaet al., 2002). Genetic studies in Drosophila melanogaster have shown that cAMP and PKA (A kinase or protein kinase A) mediated signaling is
required in a variety of processes, such as embryogenesis, pattern formation and synaptic function (Lane and Kalderon, 1993; LANE and Kalderon, 1995;
DAVIS et al. 1996; Davis et al., 1998). A kinase anchor proteins (AKAPs) modulate the specificity of PKA function by targeting and localizing PKA to
specific subcellular structures (Scott and Pawson, 2000). We will present our recent behavioral and electrophysiological studies, which show that rugose
mutants exhibit defective learning, habituation, aberrant locomotion and hyperactivity. Our cell biological studies on the larval neuromuscular junction show
abnormal synaptic architecture.
654C
Dube3a differentially regulates mEJPs in a ubiquitin dependent manner. Reese Scroggs1 , Rachel Chassen2 , Lawrence Reiter1,3. 1) Anatomy and
Neurobiology, UTHSC, Memphis, TN; 2) IPBS Program, UTHSC, Memphis, TN; 3) Neurology, UTHSC, Memphis, TN.