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The optimum conditions for pigment production by Ae. liquefaciens was found to be 30 °C and aerobic incubation, and the properties of the pigment are shown to be similar to those of the synthetic dopa-melanin referred to. The enzyme phenol oxidase was demonstrated in the culture filtrates, but not in extracts of disintegrated cells. As precursors for the pigment production, which was shown to be strictly pH dependent, DL-tyrosine, DL-dopa and catechol were used with success, while numerous other amino acids failed. The significance of the pigment as a criterium for the identification of strains which are pathogenic to certain animals or fishes, is not known.  相似文献   
76.
Abstract – Effects of local environmental influences on the structure of fish assemblages were evaluated from 159 sites in two regions of the Great Plains with limited anthropogenic disturbance. These regions offered an opportunity to evaluate the structure and variation of streams and fish assemblages within the Great Plains. We used canonical correspondence analyses to determine the influence of environmental conditions on species abundances, species occurrences and assemblage characteristics. Analysis of regions separately indicated that similar environmental factors structured streams and fish assemblages, despite differences in environmental conditions and species composition between regions. Variance in fish abundance and assemblage characteristics from both regions was best explained by metrics of stream size and associated metrics (width, depth, conductivity and instream cover). Our results provide a framework and reference for conditions and assemblage structure in North American prairie streams.  相似文献   
77.
Summary Wood storage has a great influence on the efficiency of a pulpmill. Great problems arise when using outside chip storage, especially in processing hardwoods, in that hardwood chips discolorate after a few days, which is not the case with spruce chips. The causes of such a different behavior of beech and spruce were investigated. It could be shown that a sufficient amount of active peroxidase, malate dehydrogenase and oxygen are prerequisites for the formation of phenoxy radicals within the beech lignin. This causes formation of new chromophores that discolorize the wood. Sufficient amounts of such enzymes are present in beech wood after harvesting.  相似文献   
78.
The essential oil ofChrysanthemum balsamita L. revealed insecticidal properties when tested againstM. dirhodum aphids. The insecticidal activity was attributed to the presence of pyrethrine I in the oil. By an appropriate testing procedure, the dependence of the activity upon the time of harvesting of the plants was determined. Furthermore, the insecticidal effect of the oil was compared with that of a commercially available pyrethrum preparation.  相似文献   
79.
We investigated carbon (C) uptake and respiratory losses of an adult Pinus cembra tree at the alpine timberline throughout an entire year by means of an automated, multiplexing gas exchange system. These chamber measurements were then combined with biomass data for scaling up the C budget to the tree level. Integrated over an entire year, the cumulative C gain of the tree under study was 23.5 kg of C in 2002. The daily C balance was negative for 5 months and the estimated total wintertime respiratory losses were 9% of the amount of C fixed during the growing season. The total annual C loss of the tree consumed 55% of the annual net C gain and the remaining surplus was stored in new tissues (36%) and used for fine root growth (9%). Thus, the overall C budget of P. cembra at the upper timberline is balanced fairly well, although the C sink strength in fine roots is strongly limited owing to low root zone temperatures when compared to conifers at lower elevation sites.  相似文献   
80.

Key message

Aggregated, consolidated, and derived soil physicochemical data of 286 ICP Forests Level II plots were completed with soil hydraulic properties for integrated use with forest monitoring data. Database access should be requested at http://icp-forests.net . Metadata associated available at https://metadata-afs.nancy.inra.fr/geonetwork/apps/georchestra/?uuid=153e599e-6624-4e2b-b862-8124386ea9cd&hl=eng

Context

The ICP Forests database is one of the most comprehensive forest ecosystem datasets in Europe and contains the accumulated results of more than two decades of harmonised forest monitoring all over Europe.

Aims

The aim of this paper is to share knowledge on the ICP Forests Level II soil data for broader use among forest scientists.

Methods

After standard analysis, quality checks, aggregation, and calculation of derived variables (e.g. nutrient stocks, base saturation, C:N ratio, and water retention parameters), data have been gathered into a static database (AFSCDB.LII.2.2), which will be updated to new versions as soon as new measurements become available.

Results

The database provides a basis for the combined evaluation of up to 130 unique soil variables of 286 plots with dynamic data on tree growth, ground vegetation, foliar chemistry, crown condition, tree phenology, leaf area index, ozone injury, litterfall, soil solution chemistry, deposition, ambient air quality, and meteorological data assessed on the same plots.

Conclusion

The unprecedented comprehensiveness and level of detail in this newly aggregated database may overcome existing restrictions so far impeding the realisation of large-scale forest ecosystem studies in Europe.
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