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  • 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
    [s.l.] : Nature Publishing Group
    Nature 295 (1982), S. 703-704 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Semen was collected from mature rainbow trout, Salmo gairdneri, by inserting a pipette into the sperm duct. The plasma membrane and mitochondria of the sperm were then removed (confirmed in electron micrographs) by mixing at room temperature 1 volume of semen with 20 volumes of the extracting ...
    Type of Medium: Electronic Resource
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  • 3
    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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  • 4
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 14 (1989), S. 194-200 
    ISSN: 0886-1544
    Keywords: spermatozoon ; Ca2+ ; asymmetry ; inactivation ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Spermatozoa of the rainbow trout, Salmo gairdneri, were demembranated with Triton X-100. The demembranated spermatozoa showed vigorous motility in the reactivation solution containing Ca2+ at the concentrations below 10-8.5M in the presence of cAMP. The motility was lost at 10-8M Ca2+ or more. The shape of the immotile flagella in the presence of high concentration of Ca2+ was not uniform: Some showed the cane shape and some were almost straight. The change in Ca2+ concentration of the extraction solution did not alter the motility of the reactivated spermatozoa. These results were different from those obtained from the sea urchin spermatozoa. When the concentration of cAMP was changed from 0.5 to 100 μM, the concentration of Ca2+ for converting the motile to immotile state was not altered. Thus, it is likely that the Ca2+-dependent regulatory system of flagellar movement is independent of the cAMP-induced initiation mechanism, which is assumed to require the transient influx of Ca2+ in rainbow trout spermatozoa.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1040-452X
    Keywords: Fish migration ; Axoneme ; Plasma membrane ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: In the natural process of the migration of chum salmon from the sea to the river, spermatozoa moved from the testis to the sperm duct, and the pH value of seminal plasma, concentration of cyclic adenosine monophosphate (AMP) in the sperm cells, and potential for sperm motility increased. Cyclic AMP levels and the potential for motility gradually increased when testis spermatozoa with no capacity for movement were incubated in the artificial seminal plasma of which the pH was much the same as, or higher than, the pH of natural seminal plasma from the sperm duct. Such correlation in motility, pH, and cyclic AMP suggests that the increases in seminal pH and intracellular cyclic AMP level during passage of spermatozoa from the testis to the sperm duct cause the acquisition of potential for motility. Motility of testicular spermatozoa demembranated with Triton X-100 was very low in fish caught in the sea, while motility of spermatozoa from the posterior portion of the sperm duct was much higher in fish caught in the river. Furthermore, nondemembranated, intact spermatozoa showed a lag in the timing of the acquisition of potential for motility vs. demembranated spermatozoa: The demembranated sperm exhibited the potential earlier than the nondemembranated sperm. These data suggest that increase in activity of the motile apparatus, the axoneme, is a prerequisite, in part, for the acquisition of sperm motility, whereas the development of some function of the plasma membrane also contributes to this phenomenon. © 1993 Wiley-Liss, Inc.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 6
    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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  • 7
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Gamete Research 1 (1978), S. 157-164 
    ISSN: 0148-7280
    Keywords: 1-methyladenine ; oocyte maturation ; 1-methyladenine receptor ; reconstitution of hormone receptor ; starfish ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Fully grown oocytes of the starfish Asterina pectinifera, undergo breakdown of their germinal vesicles and subsequent maturation on treatment with 1-methyladenine (1-MeAde). However, oocytes treated with seawater containing 0.010% Triton X-100 lost the capacity to respond to 1-MeAde and their germinal vesicles remained intact. These decapacitated oocytes once again ac-quired the capacity to respond to l-Me Ade when they were incubated in sea water containing the extract of fully grown oocytes treated with Triton X-100, from which the Triton X-100 was removed after extraction by means of Bio-Beads SM-2 (TXE). Recovery of the capacity was also observed after washing such TXE-treated oocytes with sea water. These results suggest that some factor (probably 1-MeAde receptor or its fragment), extracted from the oocyte surface (plasma mem-brane) by nonionic detergent, was reconstituted on the oocyte surface so that the capacity of the oocytes to respond to 1-MeAde was recovered. The factor was heat-stable and resistant to treat-ment with proteolytic enzymes.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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