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  • 1
    ISSN: 1365-2109
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract. This paper reports a series of trials on the cryopreservation of Oreochromis niloticus (L.) spermatozoa, using methanol as the cryoprotectant.Immotile milt samples pooled from four males were diluted with two diluents, each being subjected to equilibration periods of 15, 30, 45, 60 and 90 min. In addition, samples of fresh pooled milt were kept for 0, 2, 4, 6 and 8 days at 4°C prior to cryopreservation. Diluted samples were stored in 250-μl plastic straws and cooled to -50°C at 5°C/min and held under liquid nitrogen for between 1 and 3 weeks. Viability of post-thawed spermatozoa was estimated from video recordings of samples activated under a microscope and from fertilization rates of eggs.The type of diluent and its interaction with equilibration time significantly (P〈 0.05) influenced the post-thaw motility of spermatozoa. Spermatozoa stored for up to 6 days prior to cryopreservation were as fertile as freshly frozen spermatozoa and yielded 60.6 (±SE, 8.4) developing embryos.
    Materialart: Digitale Medien
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  • 2
    Digitale Medien
    Digitale Medien
    Oxford, UK : Blackwell Publishing Ltd
    Aquaculture research 17 (1986), S. 0 
    ISSN: 1365-2109
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract. Conical and round-bottomed incubating containers were evaluated for efficiency in producing Oreochromis fry. For Orcochromis niloticus (L.) and Oreochromis mossambicus (Peters): 0-, 12-, 24-, 48- and 72-h-old egg clutches were artificially incubated at 28°C in conical and round-bottomed containers. Hatching occurred within 72–84h and 90–102h after fertilization respectively compared to 96–120h for naturally incubated egg clutches. No significant differences (P 〉 0·05) were found between the hatch and survival rates of O. niloticus and O. mossambicus fry or between fry from the various ages of eggs. The type of containers, however, significantly (P 〈 0·05) influenced the hatchability and survival rates, the overall survival rate from fertilization being 60% and 85% for conical and round-bottomed containers respectively. Possible reasons for these differences are discussed. The feasibility of using the superior round-bottomed containers for artificial egg and fry incubation and the advantages for broodstock management to mass produce Oreochromis fry are discussed.
    Materialart: Digitale Medien
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  • 3
    Digitale Medien
    Digitale Medien
    Oxford, UK : Blackwell Publishing Ltd
    Aquaculture research 24 (1993), S. 0 
    ISSN: 1365-2109
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract. The effect of stocking density on growth and survival of Oreochromis niloticus (L.) fry was evaluated. O. niloticus fry (average weight, 10·56 ± 0·28mg and average length. 9·09 ± 0·05nim) were stocked in 2–1 tanks at 2, 5, 10, 15 and 20 fry/1 and reared for 33 days post fertilization, at 30°C (±1°C). Mean lengths, mean weights, and specific growth rates were found to be significantly lower (P 〈 0·05) at the higher stocking densities. The coefficient of variation for the five stocking densities was significantly (P 〈 0·05) different. Condition factors, however, were not significantly (P 〈 0·05) different and survival was high at all density treatments. These data suggest that the culture of O. niloticus is feasible at the density groups tested but 5–10fry/I is recommended for fry culture in the hatchery, if a more uniform size is desired.
    Materialart: Digitale Medien
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  • 4
    Digitale Medien
    Digitale Medien
    Melbourne, Australia : Blackwell Science Pty
    Nephrology 5 (2000), S. 0 
    ISSN: 1440-1797
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Materialart: Digitale Medien
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  • 5
    Digitale Medien
    Digitale Medien
    Melbourne, Australia : Blackwell Science Pty
    Nephrology 5 (2000), S. 0 
    ISSN: 1440-1797
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Materialart: Digitale Medien
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  • 6
    Digitale Medien
    Digitale Medien
    Amsterdam : Elsevier
    European Journal of Medicinal Chemistry 29 (1994), S. 537-549 
    ISSN: 0223-5234
    Schlagwort(e): Ptdlns ; Ptdlns 4-kinase ; inositol phospholipid
    Quelle: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Thema: Chemie und Pharmazie , Medizin
    Materialart: Digitale Medien
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  • 7
    ISSN: 1432-2242
    Schlagwort(e): Androgenesis ; Gynogenesis ; Tilapia Gene bank ; Chromosome manipulation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Androgenesis is a potentially valuable technique for recovering fish from gene banks composed of cryopreserved sperm, developing inbred lines, and analyzing patterns of inheritance. The procedure for producing diploid organisms whose nuclear DNA is wholly of paternal origin is dependent on: (1) the denucleation of “host” eggs, and (2) the inhibition of the first mitotic division in order to double the haploid sperm chromosome complement following fertilization of host eggs. Denucleation of tilapia (Oreochromis niloticus L.) eggs was carried out using UV irradiation. Treatment durations of 5–8 min (total dose of 450–720 J/m2) produced acceptable yields of viable denucleated eggs [22.9±1.6% (±SE) of controls] as estimated by the survival of haploid androgenetic tilapia to 48 h post-fertilization. Successful mitotic inhibition was accomplished using a heat-shock of 42.5 °C for 3–4 min, applied at 2.5-min intervals from 22.5 to 30 min post-fertilization (mpf). The mean survival of androgenetic diploid fish to yolk-sac absorption for treatment groups varied from 0.4% to 5.3%, relative to the controls. Differences in the suceptibility of eggs from different females to UV irradiation were a significant factor in the overall yield of androgenetic diploids. Paternal effects did not significantly influence the androgenetic yield, suggesting that individual males would not be selected against. For comparative purposes mitotic gynogenetic “mitogyne” diploids were produced from UV-irradiated sperm. Mean survival to yolk-sac absorption varied from 0.5% to 10.64%, relative to controls. Similar optima for androgenetic and gynogenetic induction were found in the period 25–27.5 mpf (minutes post-fertilization). Induction treatments would appear to be operating on the same developmental events in both these techniques, and the results suggest that the UV irradiations used do relatively little damage to the eggs beyond nuclear inactivation. The results indicate that the production of androgenetic O. niloticus is possible on a consistent basis and that the application of this technique may be useful in quantitative and conservation genetics.
    Materialart: Digitale Medien
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  • 8
    ISSN: 1612-1112
    Schlagwort(e): Column liquid chromatography ; Micellar electrokinetic capillary electrophoresis ; Tetrahydrocarbazole derivatives ; β-Cyclodextrin ; Taurodeoxycholate
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary 2,3,4,6-tetra-O-acetyl-β-D-glucopranosyl isothiocyanate derivatives of a number of basic compounds, containing one chiral center, have been prepared. The indirect resolution of enantiomers was achieved with a high separation efficiency by capillary electrophoresis, using a sodium taurodeoxycholate/β-cyclodextrin system. This methodology was found to be superior to the resolution of the same derivatives by reversed phase HPLC analysis. A possible mechanism for stereoselectivity is described.
    Materialart: Digitale Medien
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  • 9
    Digitale Medien
    Digitale Medien
    Springer
    Reviews in fish biology and fisheries 10 (2000), S. 325-337 
    ISSN: 1573-5184
    Schlagwort(e): genetic improvement ; hybridization ; stock enhancement
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract Inter-specific hybrid fishes have been produced for aquaculture and stocking programmes to increase growth rate, transfer desirable traits between species, combine desirable traits of two species into a single group of fishes, reduce unwanted reproduction through production of sterile fish or mono-sex offspring, take advantage of sexual dimorphism, increase harvestability, increase environmental tolerances, and to increase overall hardiness in culture conditions. Hybrids constitute a significant proportion of some countries' production for certain taxa; for example, hybrid striped bass in the USA, hybrid clarid catfish in Thailand, hybrid characids in Venezuela, and hybrid tilapia in Israel. Despite its widespread use, there is a general impression that inter-specific hybridization is not a very useful tool for aquaculture. We believe this impression stems from inaccurate reporting of some useful hybrids, limited testing of strains used for hybrids, and from early work on salmonids that did not result in hybrids of commercial advantage.Experimentation with new hybrid fishes is ongoing, especially in marine culture systems where sterile fish may be preferred because of the concern that fish may escape into the marine and coastal environment.Hybridization has been used in tandem with polyploidization to improve developmental stability in hybrid progeny. The results of inter-specific hybridization can be variable and depend on the genetic structure (including the sex) of the parent fish. Inadvertent hybridization and backcrossing can lead to unexpected and undesirable results in hybrid progeny, such as failure to produce sterile fish, loss of color pattern, and reduced viability.Hybridization is only one tool to improve aquaculture production and will require knowledge of the genetic structure of the broodstock, good broodstock management and monitoring of the viability and fertility of the progeny. Hybridization does represent a genetic modification wherein genes are moved between different species; implications for biodiversity conservation and regulation of this type of modification are discussed.
    Materialart: Digitale Medien
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  • 10
    Digitale Medien
    Digitale Medien
    Springer
    Digestive diseases and sciences 41 (1996), S. 2307-2316 
    ISSN: 1573-2568
    Schlagwort(e): γ-radiation ; guinea pig ; intestine ; motor activity
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract The effects of whole-body γ-radiation (10 Gy) on intestinal motor activity was examined in the small and large intestine of the guinea pig 18 hr post irradiation. Neurally mediated relaxations of isolated gut bath preparations were generally unaffected. However, the contractile responses to direct smooth muscle stimulation with the cholinergic muscarinic agonist carbachol or ganglionic stimulation of intrinsic cholinergic motor neurones were significantly increased in the duodenum and colon but not the jejunum. This increased sensitivity to cholinergic stimulation was reflected in an increased contractility and a shift in the concentration-response curves for carbachol. The specificity of radiation actions for cholinergic mediated contractions was further supported by the observation that histamine-evoked contractions were unaffected. In a second series of experiments we examined the effects of γ-radiation on the rate of pellet expulsion from freshly excised colons. Both colons from irradiated animals and nonirradiated colons exposed to carbachol showed significantly faster rates of pellet expulsion, indicative of increased propulsive motility. Pretreatment of animals with 0.5 mg/kg sc of the 5HT3 receptor antagonist Granisetron prevented the effect of radiation and reduced the pellet expulsion rate to below normal. These results indicate that gastrointestinal motility disturbances seen in organ-bath preparations of the intestine from rats exposed to whole-body γ-radiation may be related to an increased sensitivity of the cholinergic muscarinic system.
    Materialart: Digitale Medien
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