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  • 1
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Company
    Nature biotechnology 12 (1994), S. 552-552 
    ISSN: 1546-1696
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: [Auszug] To the editor: In the article “106 U.S. Biopharmaceutical Firms Lose $1.1 Billion” (Bio/Technology 12:333-335, April), the table of top 10 companies by revenue should have included Genzyme Corp. With $270,371,000 in revenues in 1993, Genzyme should have been placed ...
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-0762
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary 1. Electric organ discharge (EOD) volleys emitted by the electric catfish, Malapterurus electricus, were recorded and sampled for 108 consecutive hours from the fish's natural habitat, a selected study area in the Swashi River, a tributary of the man-made Lake Kainji in Nigeria. 2. M. electricus intermittently generates different types of EOD volleys that start with a high-frequency phase, and range in duration from 2 ms to over 8 s with from 2 to over 600 pulses (EODs). 3. The catfish's EOD activity exhibited a daily activity rhythm which was correlated with local changes in light intensity. The EOD activity remained at a constant level throughout the day from 0700 h to 1800 h. Shortly after sunset, between 1800 h and 1900 h, it increased fivefold to its peak value at 1900 h. The occurrence of EOD volleys declined throughout the night with a noticeable drop to the daytime low after sunrise between 0600 h and 0700 h. During the first 6 h following sunset, the volleys were significantly longer and consisted of more EODs than the daytime volleys. It is inferred that M. electricus feeds most successfully during the early hours of the night. 4. A hitherto unknown type of Malapterurus EOD activity was discovered: during night-time, volleys consisting of more than 16 EODs were occasionally preceded by a low-frequency train of from 1 to 11 EODs. The occurrence rate of these pre-volley EODs was positively correlated with the duration of the ensuing volley (and its number of EODs). The peak pre-volley activity occurred during the first 4 h after sunset, with an average of 38% of all volleys preceded by this type of activity. The adaptive significance of the nocturnal pre-volley EODs as prey detection mechanism is discussed.
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  • 3
    ISSN: 1432-0762
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary 1. A survey of abundance, distribution, and electric organ discharge (EOD) activity of mormyrid fish as well as associated aquatic conditions was conducted in a selected study area, 8 km upstream in the Swashi River, a tributary of Lake Kainji, Nigeria (Fig. 1). 2. Mormyrid locomotor activity and EOD repetition rate exhibited a daily activity rhythm (Fig. 2) with changes in light intensity and possibly temperature (Fig. 3b) affecting the onset and offset of the fish's nocturnal activity period. 3. Eight sympatric mormyrid species were collected: Petrocephalus bovei, Marcusenius cyprinoides, M. senegalensis, Mormyrops deliciosus, Mormyrus rume, M. hasselquisti, Hyperopisus bebe, and Pollimyrus isidori (Table 1). 4. The distribution of mormyrids with regard to pulse type, time of day, and microhabitats (inlet, opening of inlet, and river) was analysed. During the night, mormyrids were most abundant at the inlet's opening, while during their (daytime) inactive period, most EODs were monitored inside the inlet (Fig. 5: T). At the inlet's opening, a temporal separation of species (related to pulse duration, Fig. 5: S1 and S2) suggested the existence of a temporal resource partitioning mechanism.
    Type of Medium: Electronic Resource
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