title: Direct measurements of sliding between outer doublet microtubules in swimming sperm flagella.
abstract: The relative motion of 40-nanometer gold beads bound to the exposed outer doublet microtubules of demembranated sea urchin sperm flagella has been observed and photographed during adenosine triphosphate (ATP)-reactivated swimming. This direct demonstration and measure of sliding displacements between outer doublet microtubules in actively bending flagella verifies the original sliding microtubule model for ciliary bending that was established by electron microscopy of fixed cilia and provides a new, functional measure for the diameter of the flagellar axoneme of 132 +/- 8 nanometers.
authors.affiliation: Division of Biology, California Institute of Technology, Pasadena 91125.
authors.forename: C J
authors.initials: CJ
authors.lastname: Brokaw
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D006046:Gold; D008297:Male; D008870:Microtubules / Q000502:physiology*; D012617:Sea Urchins; D013081:Sperm Motility; D013082:Sperm Tail / Q000502:physiology* / Q000648:ultrastructure; D013094:Spermatozoa / Q000502:physiology*; D014741:Video Recording
chemical_list: D006046:Gold; D000255:Adenosine Triphosphate