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  • 1
    ISSN: 1573-5133
    Keywords: Sperm biology ; Sperm movement ; Sperm diluent ; Marine fish
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Synopsis Turbot sperm motility is observed using dark field microscopy and stroboscopic illumination combined with video recording. Sperm motility is triggered by dilution of spermatozoa in sea water or in non ionic media (glucose or saccharose), presenting osmotic pressure ranging from 300 to 2100 mOsmol. The percentage of motile spermatozoa reaches 100% under conditions of osmotic pressure of 300 to 1100 mOsmol and pH close to 8.0. In full sea water, glucose or saccharose solutions an agglutination of spermatozoa is observed; this is prevented by addition of bovine serum albumin (5 mg ml−1). Immediately after transfer in activation solutions, 100% spermatozoa are motile in most samples freshly stripped. This percentage drops suddenly between 15 and 30% after 70 to 100 sec. The beat frequency remains at a constant value of 50 Hz during 40 s post activation and then drops suddenly between 15 and 30 Hz. The spermatozoa velocity is about 200 micrometers s−1 during 30 to 40 s and then declines to a stable value of 100 micrometers s−1 at 50 s post activation. After 1.20 mn, more and more spermatozoa become motionless. The minimum calculated and averaged distance covered during 1.20 min, is about 12 mm. The high performances of turbot spermatozoa motility are interpreted as a compensatory mechanism for the low sperm production.
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Reviews in fish biology and fisheries 10 (2000), S. 355-392 
    ISSN: 1573-5184
    Keywords: Acipenseriformes ; conservation ; paddlefish ; phylogeny ; sturgeon ; threatened status
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The Acipenseriformes (sturgeon and paddlefish)live in the Northern Hemisphere; half of thesespecies live in Europe, mostly in thePonto-Caspian region, one third in NorthAmerica, and the rest in East Asia and Siberia.They reproduce in freshwater and most of themmigrate to the sea, either living in brackishwater (Caspian, Azov, Black and Baltic Seas) orin full seawater on the oceanic continentalshelf. Most species feed on benthic organisms.Puberty usually occurs late in life (5–30 yearsof age) and adult males and females do notspawn on an annual basis. Adults continue togrow and some species such as the beluga (Huso huso) have reached 100 years of age andmore than 1,000 kg weight. Stocks of sturgeonsare dramatically decreasing, particularly inEurasia; the world sturgeon catch was nearly28,000 t in 1982 and less than 2,000 t by 1999.This decline resulted from overfishing andenvironmental degradation such as: accumulationof pollutants in sediments, damming of rivers,and restricting water flows, which becomeunfavorable to migration and reproduction.Several protective measures have beeninstituted; for example, fishing regulation,habitat restoration, juvenile stocking, and theCITES listing of all sturgeon productsincluding caviar. In addition, sturgeon farmingpresently yields more than 2,000 t per year(equivalent to wild sturgeon landings) andabout 15 t of caviar. Hopefully, thisartificial production will contribute to areduction of fishing pressure and lead to therehabilitation of wild stocks.
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  • 3
    ISSN: 0886-1544
    Keywords: trout ; spermatozoa ; ATP ; cAMP ; axoneme ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Live trout spermatozoa initiate flagellar motility for only a short period (30 sec at 18°C) during which their mean beat frequency decreases steadily from 60 to 20 Hz. Motility then stops abruptly. Investigations of the activation of movement in demembranated sperm points to cyclic-AMP being necessary for reactivation (half effect at 0.5μm) in some conditions. cAMP acts mainly by increasing the percentage of motile cells and not the beat frequency (BF) of the flagellar axoneme. Dibutyryl cAMP does not initiate movement or prolong motility of live sperm.The initiation of movement of demembranted trout sperm was investigated in various incubation conditions relative to previous phases of in vivo movement and to ATP concentration. In the absence of cAMP and in the presence of ATP lower than 25 μM, all sperm celi models were active with BF up to 15-20 Hz whatever their previous physiological condition. In contrast, at ATP concentrations above 100 μM, the fraction of active spermatozoa decreased proportionally but the BF of the active ones increased so that, at 1 mM ATP up to 20 μM restored activity to 100% sperm models with a similar BF of 65 Hz.At ATP concentrations higher than 25 μM, cAMP was necessary in a concentration dependent manner in the reactivation, but not in the demembranation meduim. This dependence was found to be unrelated to a previous in vivo phase of movement. The antagonistic effects of ATP vs. cAMP were tested at various concentrations of both nucleotides: the apparent affinity for cAMP, measured as the concentration restoring movement of 50% cell models, was decreased from 15 nM at 0.1 mM ATP to 0.5 μM at 1 mM ATP; conversely, the affinity for ATP, measured as the concentration giving rise to the half maximal beat frequency, was not significautly affected when the concentration of cAMP was raised to 0.5 mM. Preincubation with phosphodiesterase (PDE) resulted in motility of 100% of sperm models even at low ATP concentration. This tends to show that cAMP must be constantly present to sustain motility.
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  • 4
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 14 (1989), S. 424-434 
    ISSN: 0886-1544
    Keywords: Quin-/ ; spermatozoa ; desmethoxyverapamil ; fluorescence ; K+ ; flagellar beating ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The initiation of motility of trout spermatozoa is inhibited by the presence of millimolar concentrations of external K+, but external Ca2+ might also be implicated in this control as it has been shown to antagonize the K+ inhibition of motility [S.M. Baynes et al.: J. Fish. Biol., 19:259-267, 1981]. The present work aimed to investigate internal Ca2+ levels during the motility phase of trout spermatozoa. Internal Ca2+ concentrations were monitored by the fluorescent quinoline Ca2+-indicator, “Quin-2” [R. Y. Tsien: Nature 290:527-529, 1981]. Trout spermatozoa were loaded with Quin-/ under conditions that gave efficient intracellular hydrolysis of Quin-2 and that did not impair the ability of loaded spermatozoa to initiate movement. The beat frequencies, cell velocities, and flagellar asymmetries of sperm movement were not significantly modified by the presence of the internal dye. Upon initiation of flagellar movement, an increase of the internal Quin-2 fluorescence was observed that reflected a sixfold increase of the free Ca2+ concentration. The free Ca2+ remained elevated after the cessation of movement. The variation of fluorescence was completed within 40 seconds, whereas the initiation of motility was nearly instantaneous, and the total duration of flageliar beating lasted for about 80-100 seconds (measurements at 11°C). The increase in the internal free Ca2+ concentration is completed after the initiation of flagellar beating but its occurrence correlates with that of sperm movement. Fluorescence increase was not observed in the presence of 40 mM K+, a condition in which spermatozoa did not initiate flagellar beating. In the presence of the Ca2+ channel blocker desmethoxyverapamil, neither sperm motility nor fluorescence increases were observed, which suggested that the increase of internal free Ca2+ was produced by a flux of external Ca2+ into the cell rather than by a mobilization of internal Ca2+ stores.
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  • 5
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 20 (1991), S. 55-68 
    ISSN: 0886-1544
    Keywords: motility ; spermatozoa ; calcium ; potassium ; pH ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The movement of live trout spermatozoa is very brief (25 sec at 20°C) and conditions have been developed to get synchronous initiation of sperm motility which allowed quantification of the major parameters of sperm movement during the motility phase.Recorded flagellar beat frequencies decreased steadily from values of 55 Hz at the beginning to 20 Hz at the end of the motility phase. Sperm forward velocities followed a similar pattern from 250 to 20 μm.sec-1 in the same conditions and the diameters of sperm trajectories were reduced from 370 to 40 μm. Thus none of the characteristics of sperm movement was constant during the motile phase which ended abruptly by a straightening of the flagella.The decrease in flagellar beat frequencies and sperm velocities are much greater than what could be extrapolated from the decrease of intracellular ATP (Christen R. et al: Eur. J. Biochem, 166:667-671, 1987) or from measurements of ATP-dependence of reactivated sperm velocities (Okuno M. and Morisawa N.: In Biological Functions of Microtubules and Related Structures. New York: Academic Press, pp. 151-162, 1982). Therefore, the cessation of flagellar beating at 25 sec is not directly the result of the low concentration of intracellular ATP.The decrease in the diameters of sperm trajectories which occurred during the first part of the motility phase was correlated with [Ca]i measurements (Cosson M.P. et al, Cell Motil. Cytoskeleton, 14:424-434, 1989). The effect of Ca2+ at the axonemal level does not indicates that Ca2+ influx is previous to flagellar beating but rather suggests a classical Ca2+ regulation of the flagellar assymetry.The short duration of the motility phase and the characteristics of sperm movement were very similar in various conditions (high external K+, low pH media) where increased external Ca2+ or divalent ions were shown to overcome K+ and H+ inhibition of sperm motility, both conditions which have been shown to depolarize the plasma membrane potential (Gatti J.L. et al: J. Cell Physiol., 143:546-554, 1990).The present study of the parameters of sperm movement suggests that once motility is initiated, a defined set of axonemal events will take place whatever the external conditions.
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 228 (1983), S. 205-218 
    ISSN: 1432-0878
    Keywords: Spermatozoa ; Ultrastructure ; Deep-freezing ; Sperm manipulation ; Trout
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Trout spermatozoa taken from the testis, vas deferens and ejaculate are described at the ultrastructural level. The morphology of the spermatozoa head, changes in the middle-piece structure, and the relationship between the centrioles and the flagellum were studied under consideration of their role in the reproduction of this species. Morphological changes observed after dilution of the spermatozoa in freshwater or saline and subsequent freezing deserve attention in connection with certain manipulations used in fish farms and laboratories.
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 237 (1984), S. 219-226 
    ISSN: 1432-0878
    Keywords: Spermatogonia ; Spermatocytes ; Carbohydrates ; Guppy ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The structure of guppy (Poecilia reticulata) spermatogonia and spermatocytes has been studied using electron microscopy. The spermatogonia, situated at the apex of the seminiferous tubule, are almost all surrounded by a network of Sertoli cells; they have very diffuse chromatin and one or two large nucleoli. The cytoplasm contains relatively few organelles, although annulate lamellae are found. The mitochondria have few cristae and are concentrated at one pole of the cell; they are sometimes found with intermitochondrial cement. These spermatogonia are separated from each other, having no intercellular bridges or inclusion in Sertoli cells, and are relatively undifferentiated; they correspond to stem cells. The spermatogonia beneath the apex are organized into cysts. First-generation spermatogonia are more dense and heterogeneous, their nuclei becoming smaller and their chromatin becoming denser during successive generations. In spermatocytes, the synaptinemal complex exists as a modified form until metaphase. The concentration of organelles in the cytoplasm increases and the organelles become more diversified as spermatogenesis progresses. Many cytoplasmic bridges are observed (several per cell), indicating that the cells remain in contact after several divisions. These changes in germ cell structure have been related to some of the characteristic features of spermatogenesis in guppy, e.g. the large number of spermatogonial generations and the complexity of spermiogenesis.
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 233 (1983), S. 265-284 
    ISSN: 1432-0878
    Keywords: Spermiogenesis ; Rainbow trout ; Ultrastructure ; Spermatids ; Chromatin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary In an ultrastructural study on the spermiogenesis of the rainbow trout (Salmo gairdneri R.) four spermatogenetic stages were identified. In young round spermatids, the nuclear chromatin was first heterogeneous (euchromatin and heterochromatin). Subsequently, it became more homogeneous and started to condense in the form of coarse granules and fibers and then into fibrils associated in ribbon-like elements which eventually partly fused together. During early spermiogenesis, a juxtanuclear vacuole appeared in the area where the nuclear envelope was specialized due to condensation of material between the two envelopes and a slight accumulation of nuclear material. This area was finally located in the anterior part of spermatids and spermatozoa; it probably plays a role during fertilization. A flagellar rootlet appeared early in spermiogenesis; it may play a role in the attachment of the flagellum to the nucleus since it persisted until the centriolar complex was definitively fixed in the implantation fossa. The flagellum did not display a plasma membrane and was first located in the cytoplasm, but when it was later extruded from the cell, it acquired a membrane. The cytoplasm was rich in ribosomes (free or in small groups) but poor in membranous organelles. The few mitochondria polarized around the centriolar complex were finally organized into an annular mid-piece. The spermatids remained connected by intercellular bridges until the end of spermiogenesis. The complexity of trout spermiogenesis is intermediate between that in poecilids and that in carp and pike, which have very simple spermatozoa. The role of the material from the nucleus and the cytoplasm reaching the Sertoli cell in the control of spermatogenesis has been discussed.
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  • 9
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 143 (1990), S. 546-554 
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The ionic dependence of the trout sperm plasma membrane potential was analysed by measuring the accumulation of the lipophilic ions 3H-tetraphenylphosphonium (TPP) and 14C-thiocyanate (SCN) following dilution in artificial media isotonic to the seminal fluid. Our data showed that the trout sperm plasma membrane has a mixed conductance: the plasma membrane potential is sensitive upon the transmembrane gradients of K+, Na+, and H+. This potential is negative (〈 -40mV) in a 125 mM choline chloride media (ChM) at pH 8.5. Replacement of choline by sodium has a small depolarizing effect. The membrane potential is about -15 mV in a 125 mM potassium chloride and falls near zero mV only if valinomycin is added. In ChM changing the external pH (pHe) greatly affects the membrane potential: its value rises from less than -40 mV at pHe 9.0 to -17 mV at pHe 5.0. This pH effect is observed also in presence of sodium or potassium. A decrease in the transmembrane proton gradient produced by increasing internal pH without changing pHe induces also a depolarisation of the plasma membrane. In the different media in which trout sperm remain immotile after dilution (media with [K+]〉20-40 mM or a pH 〈7.5) the plasma membrane is more depolarized than in media allowing motility, suggesting a relationship between the state of membrane polarization and the intracellular effectors of the axonemal movement.
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  • 10
    Publication Date: 1984-08-01
    Print ISSN: 0302-766X
    Electronic ISSN: 1432-0878
    Topics: Biology , Medicine
    Published by Springer
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