title: Lengths of immunolabeled ciliary microtubules in frog photoreceptor outer segments.
abstract: Monoclonal anti-tubulin antibodies were used to label microtubules in the connecting cilia and outer segments of retinal photoreceptors isolated from Rana pipiens. In paraformaldehyde-fixed rods from frogs maintained on diurnal light cycles, the anti-tubulin labeling of ciliary microtubules (mean length = 27 micron) typically extends to slightly over half the length of the outer segments (mean length = 46 micron). Rod outer segments from frogs kept in constant darkness for 3-4 weeks are longer (mean length = 53 micron) than rod outer segments from frogs maintained in cyclic lighting. However, the distribution of fractional lengths of anti-tubulin labeling of ciliary microtubules is the same for both lighting regimens. Incubating retinas in 1.0 mM colchicine prior to outer-segment fixation has no effect on the length of immunolabeling of ciliary microtubules, suggesting that post-mortem elongation artifacts are not significant. Incubating retinas in 10 microM taxol prior to fixation significantly increases the length of stained ciliary microtubules, suggesting that taxol either promotes post-mortem assembly of microtubules, or that taxol reduces post-mortem disassembly. The mean position of the end of anti-tubulin-labeled ciliary microtubules does not correspond to the position of disk shedding for any of the experimental conditions employed.
mesh_terms: D000470:Alkaloids / Q000494:pharmacology; D000818:Animals; D002923:Cilia / Q000648:ultrastructure; D003624:Darkness; D008870:Microtubules / Q000187:drug effects / Q000648:ultrastructure*; D017239:Paclitaxel; D010786:Photoreceptor Cells / Q000648:ultrastructure*; D011894:Rana pipiens; D012374:Rod Cell Outer Segment / Q000648:ultrastructure*; D014404:Tubulin / Q000276:immunology
chemical_list: D000470:Alkaloids; D014404:Tubulin; D017239:Paclitaxel