lec13_david_pier

lec13_david_pier - ► Tom Davidson ► 9 181 ► 29 Mar 05...

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Unformatted text preview: ► Tom Davidson ► 9. 181 ► 29 Mar 05 ► Across biology, other receptor-mediated systems show adaptation (de-/re- sensitization... ► Does axonal pathfinding involve adaptation? ► If so, how is this adaptation accomplished? Uses of adaptation (proposed): ► ‘Homeostatic reset’ -- getting out of the grasp of a gradient to be able to see another gradient of the same ligand ► ‘recalibration’ -- Adjust sensitivity in a graded way to increase dynamic range, allow growth up/down long gradients Growth Cone Collapse Assay ► Embryonic Xenopus retinal culture ► Pre-treat with low doses (LD) of chemotropic agents for varying times (+/-drugs), then treat with a high dose of same agent for 10 min ► Fix and count collapsed growth cones (movie) Fig. 1a ource: Pi p er, M., S. Salih, C. Weinl, C. E. Holt, and W. A. Harris. "Endocytosis-Dependent Desensitization and Protein Synthesis - Dependent Resensitization in Retinal growth Cone Adaptation." Nature Neuroscience , 2005. Published nline. Courtesy of the authors. Used with permission. Time Course of Adaptation ► ~35% basal collapse rate (control not shown) ► Sema3a desensitization after 2min, resensitization avter 4min; Netrin desens’n 1min, resens’n 4min Fig. 1b Source: Pi p...
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This note was uploaded on 11/11/2011 for the course BIO 7.344 taught by Professor Bobsauer during the Spring '08 term at MIT.

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lec13_david_pier - ► Tom Davidson ► 9 181 ► 29 Mar 05...

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