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  • K+ channel blockers  (1)
  • Key words Test cell  (1)
  • intracellular Ca2+  (1)
  • 1
    ISSN: 1432-041X
    Keywords: Key words Test cell ; Demembranated larva ; Metamorphosis ; Lectin ; Ascidian
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  The larvae of the ascidian Ciona intestinalis from which the chorion with the test cells and follicle cells were removed developed normally without the test cells until the early tailbud stage. A number of round-shaped cells morphologically similar to the test cells but with different lectin affinities and autofluorescence, then appeared on the neck region of the demembranated embryos. The new cells had three different types: round, particulate, and granular, and these cells increased in number after the late tailbud stage. The morphology of the adhesive papillae, tunic layers and epidermis of the demembranated larvae was similar to that of control larvae; however, the affinity to lectins was different in the swimming period. Control larvae attached to the substratum after the swimming period, resorbed the tail completely and underwent rotation of the visceral organs. Conversely, rotation occurred before completion of tail resorption in the demembranated larvae. Furthermore, the metamorphic events progressed more slowly in the demembranated larvae. These results suggest that the test cells play important roles in normal development and morphogenesis of ascidian larvae.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 25 (1993), S. 171-178 
    ISSN: 0886-1544
    Keywords: sperm ; motility ; osmolality ; intracellular Ca2+ ; intracellular pH ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Spermatozoa of marine teleosts, puffers and flounder, wee completely quiescent when they were washed to remove electrolytic components of the seminal plasma and then diluted in nonelectrolyte solutions isotonic to the seminal plasma. Sperm motility was initiated upon dilution in hypertonic nonelectrolyte solutions. These observations suggest that sperm motility is suppressed by seminal osmolality and motility is triggered solely by the increase in external osmolality which occurs at natural spawning in hypertonic seawater. Extracellular Ca2+ had no influence on the osmolality-dependent initiation of sperm motility. However, sperm motility was initiated even in isotonic solution when Ca2+ was introduced into the sperm cells by Ca2+ ionophore. Intracellular Ca2+ increased at the osmolality-dependent initiation of sperm motility under Ca2+ -free conditions. These results suggest that the release of Ca2+ from intracellular storage in response to the increase in external osmolality has a key role in the initiation of sperm motility. A transient increase in intracellular pH was also observed at the hyperosmolality-dependent initiation of sperm motility. Furthermore, initiation of sperm motility was induced even in isotonic solutions when intracellular pH increased by the treatment with ammonium salts. These results suggest that an increase in intracellular pH, as well as the rise in intracellular Ca2+, has an important role in the initiation of sperm motility in marine teleosts. © 1993 Wiley-Liss, Inc.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Molecular Reproduction and Development 39 (1994), S. 409-414 
    ISSN: 1040-452X
    Keywords: K+ channel blockers ; K+ electrode ; Fura-2 ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Flux of K+ and changes in intracellular Ca2+ in the sperm of salmonid fishes were measured with spectrophotometry, ion electrode, microscopic fluorometry, and radioisotope accumulation. Release of K+ occurred at the initiation of sperm motility which is induced by decrease in external K+ and the K+ efflux and sperm motility were inhibited by K+ channel blockers. Intracellular Ca2+ increased within a short period in K+- free condition, and the accumulation of 45Ca in sperm cells was higher in motile sperm than that in immotile sperm. The efflux of K+ and the increase in intracellular Ca2+ were suppressed when external K+ concentration increased, i.e., sperm remained immotile. These results suggest that efflux of K+ through K+ channel and subseqent increase in intracellular Ca2+ are prerequisite for the initiation of sperm motility. © 1994 Wiley-Liss, Inc.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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