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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Archives of microbiology 134 (1983), S. 45-48 
    ISSN: 1432-072X
    Keywords: Nitrogenase ; Methylamine ; Nitrogenase switch-off ; Rhodopseudomonas capsulata
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In the photosynthetic bacterium Rhodopseudomonas capsulata, NH 4 + switch-off of nitrogenase activity can be mimicked by its analog, methylamine. Like NH 4 + , methylamine appeared to require processing by glutamine synthetase (GS) before it was effective; γ-glutamylmethylamide was shown to be the product of this reaction. Evidence that this glutamine analog functioned directly to initiate nitrogenase inactivation was suggested first by the fact that it was a poor substrate for glutamate synthase (i.e., it was not further metabolized by this pathway) and secondly, azaserine which blocks the transfer of the glutamine amide group had no effect on CH3NH 3 + (or NH 4 + ) switch-off. These observations are taken as preliminary evidence to suggest that when NH 4 + inhibits nitrogenase activity, inactivation is initiated by glutamine itself, and not a molecule derived from it. Finally, evidence was presented that R. capsulata would use CH3NH 3 + as a nitrogen substrate, but lag periods and generation times increased with subsequent passages.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Hydrobiologia 251 (1993), S. 321-329 
    ISSN: 1573-5117
    Keywords: multi-pond system ; non-point pollution ; ecotone ; filtering effects
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A study was carried out in the small watershed of Chaohu Lake, where a scattered multi-pond system, as a part of the land-inland water ecotone, was found to be a good protective zone in the management of the lake. This multi-pond system can effectively reduce the non-point source load of nutrients, such as phosphorus and nitrogen from runoff water, and filter out sediments before they reach the lake. There are 150 artificial ponds in this small watershed, covering a surface area of 35.54 ha, which represents just under 5% of the whole catchment area. The nutrient retention in the first 9 months of the dry year 1988 was more than 90%. This multi-pond system needs low capital cost and energy consumption for maintenance, and is suitable for irrigation and drainage, while it recycles water and nutrients within the terrestrial agroecosystem. As a result of this case study, a multipond system is being proposed as part of a long term management strategy for the watershed.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
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