Using semaphorins to assemble an olfactory circuit
Abstract/Contents
- Abstract
- The Drosophila olfactory system is an excellent model to study how neural circuits develop their complex structure and precise connectivity. Olfactory receptor neurons (ORNs) expressing the same odorant receptor, and thus sensing the same odorants, are scattered in the peripheral antenna and maxillary palp. Remarkably, these distributed ORNs expressing the same receptor converge their axons onto one discrete structural unit in the central brain termed a glomerulus. In each glomerulus, ORNs synapse with a single class of central projection neurons (PNs) that send their dendrites into one glomerulus and their axons to higher brain centers. Demonstrating this striking axonal specificity, the 1300 ORNs in the antenna expressing approximately 50 different odorant receptors segregate their axons into discrete 50 discrete glomeruli in the antennal lobe. This highly ordered olfactory circuit begs the question: how do ORN axons and PN dendrites achieve this remarkable level of convergence onto one of fifty glomeruli? My study of the Semaphorin protein family has revealed new cellular strategies for precise ORN axon and PN dendrite targeting. Semaphorins are highly conserved cell surface proteins that have been shown to function as neuronal "semaphores" to guide developing neurons. In ORNs, the transmembrane Sema-1a promotes axon-axon repulsion between two populations of ORNs to spatially restrict their targeting in the antennal lobe (Sweeney et al., 2007). In PNs, Sema-1a functions as a receptor to control PN dendrite targeting in a continuous molecular gradient (Komiyama et al., 2007). The secreted and highly homologous Sema-2a and Sema-2b produced by the ventromedial degenerating larval antennal lobe function in a countergradient as the Sema-1a ligand to repel dorsolateral PN dendrites (In preparation). Semaphorin function in Drosophila olfactory wiring demonstrates two novel strategies for neural circuit assembly: spatial cues from surrounding axons and from degenerating structures instruct precise targeting.
Description
| Type of resource | text |
|---|---|
| Form | electronic; electronic resource; remote |
| Extent | 1 online resource. |
| Copyright date | 2011 |
| Publication date | 2010, c2011; 2010 |
| Issuance | monographic |
| Language | English |
Creators/Contributors
| Associated with | Sweeney, Lora Beatrice | |
|---|---|---|
| Associated with | Stanford University, Neurosciences Program | |
| Primary advisor | Luo, Liqun, 1966- | |
| Thesis advisor | Luo, Liqun, 1966- | |
| Thesis advisor | Clandinin, Thomas R. (Thomas Robert), 1970- | |
| Thesis advisor | Nelson, W. J. (W. James) | |
| Thesis advisor | Shen, Kang,d1972- | |
| Advisor | Clandinin, Thomas R. (Thomas Robert), 1970- | |
| Advisor | Nelson, W. J. (W. James) | |
| Advisor | Shen, Kang,d1972- |
Subjects
| Genre | Theses |
|---|
Bibliographic information
| Statement of responsibility | Lora Beatrice Sweeney. |
|---|---|
| Note | Submitted to the Program in Neurosciences. |
| Thesis | Ph.D. Stanford University 2011 |
| Location | electronic resource |
Access conditions
- Copyright
- © 2011 by Lora Beatrice Sweeney
- License
- This work is licensed under a Creative Commons Attribution Non Commercial 3.0 Unported license (CC BY-NC).
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