title: Reactivation of outer-arm-depleted lung axonemes: evidence for functional differences between inner and outer dynein arms in situ.
abstract: Demembranated axonemes isolated from newt lung ciliated cells show a complex beat frequency response to varying [MgATP] and temperature [Hard and Cypher, 1992, Cell Motil. Cytoskeleton 21:187-198]. The present study was undertaken to ascertain whether the beat frequency of outer-arm-depleted newt lung axonemes is controlled in a manner similar to that of intact axonemes. Populations of demembranated ciliary axonemes were isolated by Triton X-100 extraction of lungs from the newt, Taricha granulosa. Aliquots of the demembranated axonemes were further treated with solutions containing high salt (0.375 M KC1) and 1.25 mM MgATP. This treatment resulted in the selective removal of outer dynein arms and a concomitant decrease in beat frequency to a stable level, 33-35% of control values. The effects of pH, salt concentration, nucleotides, and temperature on the beat frequency of reactivated outer-arm-depleted axonemes were ascertained and compared with those of intact axonemes. Some reactivation properties, such as nucleotide specificity, the effect of pH on beat frequency and the threshold [MgATP] required for reactivation (approximately 5 microM) were similar to those observed for intact axonemes. Other properties, such as the relationship between beat frequency and varying [MgATP] or salt concentration, differed both qualitatively and quantitatively from those of control axonemes, as did their response to temperature over the range, 5 degrees-32 degrees C. The nature of the results obtained with temperature and MgATP suggests that inner and outer dynein arms are not functionally equivalent in situ.
authors.affiliation: Department of Anatomical Sciences, School of Medicine, State University of New York Buffalo 14214.
authors.forename: R
authors.initials: R
authors.lastname: Hard
authors.forename: K
authors.initials: K
authors.lastname: Blaustein
authors.forename: L
authors.initials: L
authors.lastname: Scarcello
mesh_terms: D000255:Adenosine Triphosphate / Q000494:pharmacology; D000818:Animals; D002923:Cilia / Q000187:drug effects / Q000502:physiology* / Q000648:ultrastructure; D004398:Dyneins / Q000494:pharmacology*; D004847:Epithelial Cells; D004848:Epithelium / Q000502:physiology; D006358:Hot Temperature; D006863:Hydrogen-Ion Concentration; D007091:Image Processing, Computer-Assisted; D008168:Lung / Q000166:cytology / Q000502:physiology*; D008853:Microscopy / Q000379:methods; D008954:Models, Biological; D012455:Salamandridae / Q000033:anatomy & histology / Q000502:physiology*; D012492:Salts / Q000494:pharmacology; D013379:Substrate Specificity; D014741:Video Recording
chemical_list: D012492:Salts; D000255:Adenosine Triphosphate; D004398:Dyneins