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1. The responses of starfish sperm flagella to mechanical stimulation with a microneedle were analysed. Flagellar movement was recorded by high-speed microcinematography and by stroboscopic observation. 2. The amplitude of the bending wave of a flagellum was restricted over its entire length when the microneedle was brought near to the flagellum at its(More)
Intracellular release of Ca2+ by microinjection of Ca2+ was analyzed by measuring the luminescence of aequorin loaded in eggs of the medaka (Oryzias latipes). Microinjection of Ca2+ into the cortical cytoplasm induced propagative waves of cytoplasmic Ca2+ release and exocytosis of cortical alveoli initiated at the injection point. The Ca2+ wave was(More)
Changes in the intracellular free calcium levels in the cortical region of cleaving Xenopus eggs were examined using semi-synthetic aequorin. We detected periodic oscillations in the free calcium levels accompanying the cleavage cycle as early as the first cleavage onward. The calcium levels began to increase at early interphase and were maximal during(More)
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(More)
Birefringence of the mitotic apparatus (MA) and its change during mitosis in sea urchin eggs were quantitatively determined using the birefringence detection apparatus reported in the preceding paper (Hiramoto el al., 1981, J. Cell Biol. 89:115-120). The birefringence and the form of the MA are represented by five parameters: peak retardation (delta p),(More)
Electron microscope preparations were made of specimens of Actinosphaerium nucleofilum fixed in glutaraldehyde before, during, and after exposure to high pressures (4,000 to 8,000 psi). A study of this material showed that, although other organelles were relatively stable, the microtubular elements of the axopodia and cytosome became unstable under(More)
Eggs of Xenopus laevis were preloaded with aequorin and the spatial and temporal pattern of free calcium release in the egg cortex on artificial activation was determined by the aequorin luminescence emitted from the thin cortical layer of naturally opaque eggs. The aequorin luminescence was detected with a photonic microscope system consisting of a light(More)