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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Journal of comparative physiology 92 (1974), S. 181-200 
    ISSN: 1432-1351
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary 1. Gnathonemus petersii respond to each other's electric organ discharge (EOD) with an “echo” discharge of their own at a latency of about 12 msec. This response persists until interfish distances reach about 30 cm (Fig. 4). 2. Artificial electrical stimuli were used to further characterize the response. Response threshold, latency dependence on stimulus intensity, polarity characteristics (Figs. 5–7), and differential regional sensitivity indicate that “medium” electroreceptors in the anterior region of the animal underlie the response. 3. Response probability depends upon the delay of the stimulus after the last EOD and also upon the instantaneous EOD rate (Figs. 8, 9). The echo response in turn resets the EOD rhythm of the responding animal (Fig. 10). These results suggest that the echo input pathway terminates on the presumed mesencephalic command center.
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Journal of comparative physiology 92 (1974), S. 201-228 
    ISSN: 1432-1351
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary 1. The electric organ discharge (EOD) patterns seen in pairs of mormyrid fishes (Gnathonemus petersii) during displays related to aggression and establishment of dominance are described. 2. A new method of reliably separating the discharges of the two fish was used. In this method a fine wire was attached to the tail of one animal (Fig. 1). 3. Discharge patterns were examined at different stages during the characteristic sequence of overt behavioral events which usually occurred after an intruder was put into a tank in which another fish of the same species had been resident for 1 hour or more. The resident attacked the intruder immediately, the intruder being initially unresponsive. After a few minutes, however, the two fish entered into intense, mutual, antiparallel displays (Fig. 2). The displays occurred repeatedly during a period of 0.5–30 min. This period ended suddenly with one of the fish clearly dominant as shown by one-sided attacks and avoiding behavior by the submissive fish. 4. All attacks were accompanied by a smooth acceleration to a high discharge rate which was usually terminated abruptly (Fig. 3). Anti-parallel behavior was accompanied by similar accelerations in both fish. Interdischarge intervals during these high rates changed discretely between those of about 15 msec and those of about 9 msec (Figs. 3–9). Initial attacks before the antiparallel period usually produced no effect or a brief acceleration in the discharges of the attacked animal. Similar attacks when dominance was well established caused a slowing of the discharge rate of the attacked fish. 5. The echo response in which one fish responds to the EOD of another with a discharge of its own at a latency between 11 and 14 msec was seen at all stages of the encounter. This latency corresponded rather exactly to the gap in the interval histogram between the shorter intervals around 9 msec and the longer ones around 15 (Figs. 11, 12). This correspondence led to a degree of avoidance of near synchronous discharges during those attacks which did not cause either slowing or accelerations in the attacked animal (Fig. 11). A degree of synchrony avoidance also occurred during the mutually high discharge rates of antiparallel behavior. This resulted from the phase locking of the two discharge trains which was often present at these times and which was probably due to the echo responses (Fig. 13). 6. Several features of the individual discharge trains and of their interaction were examined during the period of antiparallel activity. This was done in order to see if some critical parameter could be detected which would allow one to predict the winner of the encounter and which might be used as a signal by the fish themselves. No single feature among those we examined was clearly and consistently related to the outcome of the encounter.
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  • 3
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Group
    Nature 134 (1934), S. 290-290 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] MY scepticism regarding the frequent statement, for example, Bischoff1, that worker bees (Apis mellifica) cannot withdraw their barbed sting, and thus invariably die when they have stung, was first aroused by observing a raid by wasps (Vespa germanica) on a hive in Essex, in ...
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  • 4
    Electronic Resource
    Electronic Resource
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Plant Physiology 22 (1971), S. 289-312 
    ISSN: 0066-4294
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Biology
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Aquaculture research 26 (1995), S. 0 
    ISSN: 1365-2109
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1432-203X
    Keywords: Key words Garlic ; Allium sativum L. ; Root segments ; Regeneration ; Picloram
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Root segments from shoot tip-derived plantlets of the garlic (Allium sativum L.) clones `DDR7099', `PI383819', and `Piacenza' were utilized as an explant source for continuous, friable callus production. The best callus production occurred on root segments initially cultured on medium with 4,5 μm 2,4-dichlorophenoxyacetic acid (2,4-D) for 8 weeks, then subcultured to medium with 4.7 μm 4-amino-3,5,6-trichloropicolinic acid (picloram) +0.49 μm 6-(γ-γ-dimethylallylamino)purine (2iP) for 8 weeks. Embryogenic, friable callus was transferred to liquid medium for 1 month and then transferred to solid regeneration medium for 14 weeks. The best shoot and root regeneration (85.3% and 35.8%, respectively) occurred on 4-month-old calli from the clone `DDR7099'. In all clones, regeneration rate decreased as callus age increased.
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  • 7
    ISSN: 1432-203X
    Keywords: Key words Allium sativum ; Benzyladenine ; Picloram ; Thidiazuron ; 2 ; 4-D ; 2iP
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  A long-term regeneration system for garlic (Allium sativum L.) clones of diverse origin was developed. Callus was initiated on a modified Gamborg's B-5 medium supplemented with 4.5 μM 2,4-D and maintained on the same basal medium with 4.7 μM picloram+0.49 μM 2iP. Regeneration potential of callus after 5, 12 and 16 months on maintenance medium was measured using several plant growth regulator treatments. The 1.4 μM picloram+13.3 μM BA treatment stimulated the highest rate of shoot production. Regeneration rate decreased as callus age increased, but healthy plantlets from callus cultures up to 16-months-old were produced for all clones. Regeneration of long-term garlic callus cultures could be useful for clonal propagation and transformation.
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  • 8
    ISSN: 1432-2242
    Keywords: Androgenesis ; Gynogenesis ; Tilapia Gene bank ; Chromosome manipulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: 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.
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  • 9
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 82 (1913), S. 278-282 
    ISSN: 0863-1778
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 80 (1913), S. 93-103 
    ISSN: 0863-1778
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Aus den Versuchen ergibt sich, daß Cuprohydrid bei der Reaktion zwischen Kupfersulfat und unterphosphoriger Säure entsteht, daß aber die Reinheit des Produktes von begrenzten Versuchsbedingungen, besonders von Temperatur und Zeit abhängt. Die Versuche bei gewöhnlicher Temperatur zeigen, daß nach mehrstündigem Stehen das Produkt Hydrid und Oxyd enthält, und auf die Koexistenz dieser beiden Stoffe ist die Explosionsfähigkeit der trockenen Substanz bei Berührung mit Luft zurückzuführen.
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