title: Flexural rigidity of echinoderm sperm flagella.
abstract: The stiffness (flexural rigidity) of live sperm flagella, Triton-demembranated flagella (axonemes), trypsin-digested axonemes, and doublet microtubules of the axonemes in echinoderms was determined from the relationship between their deformation when a stream of medium was applied and the viscous resistance of the medium acting on the flagellum. The stiffness of the flagellum beating in seawater was 5.8 x 10(-21) Nm2 for bending in the direction perpendicular to the beating plane and 4.2 x 10(-22) Nm2 for bending within the beating plane. A similar difference in stiffness from the difference in bending directions was found in reactivated flagella with 1 mM ATP. The stiffness of live flagella immobilized in CO2-saturated seawater and axonemes in ATP-free medium was similar to that of beating flagella for bending in the direction perpendicular to the beating plane. The stiffness of motionless flagella significantly decreased with erythro-9-(2-hydroxy-3-nonyl) adenine (EHNA) and vanadate. The trypsin-digestion of motionless axonemes did not change their stiffness. The stiffness of doublet microtubules was 1.4 x 10(-23) Nm2 in 0.1 mM ATP medium and 6.1 x 10(-23) Nm2 in ATP-free medium. These results suggest that doublet pairs lying parallel to the beating plane of the flagellum retain fewer cross-bridges than doublet pairs lying perpendicular to the beating plane.
authors.affiliation: Biological Laboratory, Faculty of Science, Tokyo Institute of Technology, Japan.
authors.forename: S
authors.initials: S
authors.lastname: Ishijima
authors.forename: Y
authors.initials: Y
authors.lastname: Hiramoto
mesh_terms: D000225:Adenine / Q000031:analogs & derivatives / Q000494:pharmacology; D000818:Animals; D004398:Dyneins / Q000037:antagonists & inhibitors; D008297:Male; D009068:Movement / Q000502:physiology*; D017830:Octoxynol / Q000494:pharmacology; D018583:Pliability; D012617:Sea Urchins / Q000502:physiology* / Q000648:ultrastructure; D013082:Sperm Tail / Q000502:physiology* / Q000648:ultrastructure; D014357:Trypsin / Q000494:pharmacology; D014638:Vanadates / Q000494:pharmacology; D014783:Viscosity
chemical_list: D014638:Vanadates; C010192:9-(2-hydroxy-3-nonyl)adenine; D017830:Octoxynol; D014357:Trypsin; D004398:Dyneins; D000225:Adenine