We will analyze the actions of genes regulating the formation and function of photoreceptor synapses in Drosophila. Our previous work on tetrad synapses at these genetically manipulable model photoreceptor terminals and their target interneurons, helps establish the lamina as the fly's functional counterpart to the retina's outer plexiform layer. Our long-term objective is to understand the functional organization of multiple-contact synapses (dyads, triads, etc.), how these form, the reactive changes they manifest, and the role of neural activity in these events. Current objectives are to study genetic mutants that regulate how tetrad and feedback synapses form at photoreceptor terminals, either during recognition of postysynaptic targets or later, when synaptic organelles are targeted to sites of such contact. We will examine mutant photoreceptors, in homozygous flies or in whole-eye mosaics, by means of advanced methods of confocal and electron microscopy, and our skilled personnel to implement these. We are developing innovative EM tomographic and freeze-substitution methods. We will examine: A. The functional role of genes such as Dscam and N-cadherin, acting during target selection by photoreceptor terminals;as well as imac and dHIP14, required to target synaptic organelles to the terminals. B. The reactive synaptic changes among the lamina's feedback synapses that occur when transmission from photoreceptors is reversibly blocked by a temperature-sensitive construct of Drosophila dynamin. C. High-resolution EM tomography, to identify protein complexes that are perturbed at mutant synapses, which we will label with Fab antibody fragments. We will also continue to: D. Identify proteins expressed at synaptic organelles, using either immuno-gold methods, or by tagging identified proteins and labeling these by the ReAsH method. E. Analyze synaptic micro-circuits in the distal strata of the second neuropile, or medulla, that originate from photoreceptor and lamina cell terminals, using serial-EM and targeted HRP expression. We will identify ways in which these circuits change when photoreceptors are mutant for the genes Lar or curta. Our proposed studies aim to produce a basic model of synaptogenesis applicable to multiple-contact synapses, such as the retina's dyads and triads, and help identify the underlying genetic bases for changes that result from congenital or dystrophic diseases, or retinal damage, and reactive rearrangements to these among the retina's synapses.

Agency
National Institute of Health (NIH)
Institute
National Eye Institute (NEI)
Type
Research Project (R01)
Project #
5R01EY003592-30
Application #
7878635
Study Section
Biology and Diseases of the Posterior Eye Study Section (BDPE)
Program Officer
Mariani, Andrew P
Project Start
1981-02-01
Project End
2011-03-31
Budget Start
2010-04-01
Budget End
2011-03-31
Support Year
30
Fiscal Year
2010
Total Cost
$233,593
Indirect Cost
Name
Dalhousie University
Department
Type
DUNS #
207799404
City
Halifax, Nova Scotia
State
NS
Country
Canada
Zip Code
B3 4-R2
Shinomiya, Kazunori; Takemura, Shin-ya; Rivlin, Patricia K et al. (2015) A common evolutionary origin for the ON- and OFF-edge motion detection pathways of the Drosophila visual system. Front Neural Circuits 9:33
Schwabe, Tina; Borycz, Jolanta A; Meinertzhagen, Ian A et al. (2014) Differential adhesion determines the organization of synaptic fascicles in the Drosophila visual system. Curr Biol 24:1304-1313
Lüthy, Kevin; Ahrens, Birgit; Rawal, Shilpa et al. (2014) The irre cell recognition module (IRM) protein Kirre is required to form the reciprocal synaptic network of L4 neurons in the Drosophila lamina. J Neurogenet 28:291-301
Shinomiya, Kazunori; Karuppudurai, Thangavel; Lin, Tzu-Yang et al. (2014) Candidate neural substrates for off-edge motion detection in Drosophila. Curr Biol 24:1062-70
Cherry, Smita; Jin, Eugene Jennifer; Ozel, Mehmet Neset et al. (2013) Charcot-Marie-Tooth 2B mutations in rab7 cause dosage-dependent neurodegeneration due to partial loss of function. Elife 2:e01064
Meinertzhagen, Ian A; Lee, Chi-Hon (2012) The genetic analysis of functional connectomics in Drosophila. Adv Genet 80:99-151
Haberman, Adam; Williamson, W Ryan; Epstein, Daniel et al. (2012) The synaptic vesicle SNARE neuronal Synaptobrevin promotes endolysosomal degradation and prevents neurodegeneration. J Cell Biol 196:261-76
Edwards, Tara N; Nuschke, Andrea C; Nern, Aljoscha et al. (2012) Organization and metamorphosis of glia in the Drosophila visual system. J Comp Neurol 520:2067-85
Borycz, Janusz; Borycz, Jolanta A; Edwards, Tara N et al. (2012) The metabolism of histamine in the Drosophila optic lobe involves an ommatidial pathway: ýý-alanine recycles through the retina. J Exp Biol 215:1399-411
Takemura, Shin-ya; Karuppudurai, Thangavel; Ting, Chun-Yuan et al. (2011) Cholinergic circuits integrate neighboring visual signals in a Drosophila motion detection pathway. Curr Biol 21:2077-84

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