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981.
Rachana Bhatt K. C. Patel Ujjval Trivedi 《Journal of Polymers and the Environment》2010,18(2):141-147
An extracellular poly(3-hydroxybutyrate) (PHB) depolymerase produced by a thermotolerant fungal soil isolate, Aspergillus fumigatus 202, was purified and characterized. Maximum PHB depolymerase production was obtained at the end of 48 h with initial medium
pH 7.0 and 45 °C in Bushnell Haas Minerals medium containing PHB as sole source of carbon. The PHB depolymerase was purified
using size exclusion chromatography to a fold purification of 20.62 and 61.62% yield. SDS-PAGE and isoelectric focusing revealed
the molecular weight and pI of the purified enzyme as 63,744 Da and 4.2, respectively. N-terminal amino acid sequence of purified
enzyme was HAXDAYLVK. This non-glycosylated enzyme was most active at pH 9.0 and 45 °C. Purified enzyme was inactivated by
N-bromosuccinimide and dithiothreitol suggesting the involvement of tryptophan residues and disulfide bonds at its active
site. Nonionic detergents like Tween 20, Tween 80 and Triton X-100 inhibited the enzyme activity. Ions like Ca+2 and Mg+2 (5 mM) increased the enzyme activity 1.5 times. Fe+2 effectively inhibited the enzyme activity to 88% whereas Hg+2 completely inhibited the enzyme. 相似文献
982.
T Zeevaert A Bousher V Brendler P H Jensen S Nordlinder 《Journal of environmental radioactivity》2001,56(1-2):33-50
An international project, whose aim was the development of a transparent and robust method for evaluating and ranking restoration strategies for radioactively contaminated sites (RESTRAT), was carried out under the Fourth Framework of the Nuclear Fission Safety Programme of the EU. The evaluation and ranking procedure used was based on the principles of justification and optimisation for radiation protection. A multi-attribute utility analysis was applied to allow for the inclusion of radiological health effects, economic costs and social factors. Values of these attributes were converted into utility values by applying linear utility functions and weighting factors, derived from scaling constants and expert judgement. The uncertainties and variabilities associated with these utility functions and weighting factors were dealt with by a probabilistic approach which utilised a Latin Hypercube Sampling technique. Potentially relevant restoration techniques were identified and their characteristics determined through a literature review. The methodology developed by this project has been illustrated by application to representative examples of different categories of contaminated sites; a waste disposal site, a uranium tailing site and a contaminated freshwater river. 相似文献
983.
The placement of 1918 redwing nests has been analyzed, including 214 nests of 90 marked females (2–8 known nests per female). A high level of intraspecific and individual variation in utilization of different types of nest supports is described. It is shown that redwings choose nest sites without regard to previous experience (either positive or negative) or to the placement of their parent nest. Under conditions of the northern taiga, such behavior provides for significant reduction of chick mortality by the end of the season. This is con- firmed by comparison with the song thrush (T. philomelos), which nests mainly on spruce trees. 相似文献
984.
An attempt has been made to make a comprehensive assessment of biological factors in the ecology of humus formation in forest-steppe
and steppe chernozem soils of the Cisural region. Certain regional features in the effect of vegetation structure and composition
and soil microbial and enzymatic activities on the humus state of zonal chernozem subtypes in virgin and plowed landscapes
have been revealed. 相似文献
985.
Heide Spiegel Manfred Sager Michael Oberforster Klemens Mechtler Hans Peter Stüger Andreas Baumgarten 《Environmental geochemistry and health》2009,31(5):549-560
Eighteen representative sites for the Austrian grain-growing and eight for the potato-growing zones (soils and crops) were
investigated. On each site, total element contents (B, Ba, Ca, Cd, Co, Cu, Fe, K, Li, Mg, Mn, Mo, Na, P, Sr and Zn) were determined
in 4–12 varieties of winter wheat (n = 136), 6 varieties of spring durum wheat (n = 30), 5 varieties of winter durum wheat (n = 15), 7 varieties of rye (n = 49), 5 varieties of spring barley (n = 30) and 5 varieties of potatoes (n = 40). Element accumulations in grain species and potato tubers varied significantly with site conditions, with the main
exceptions for B in potatoes and wheat as well as for Zn, Cu and Co in durum wheat. On average, across all investigated sites,
differences in varieties occurred concerning the elements Ca, Cd, Ba, Sr and Zn (except Zn in potatoes and winter durum).
A rough estimation revealed that an average Austrian consumer of wheat, rye and potatoes meets more than 50% of the needs
of daily element intake for K, P and Mg, between 36 and 72% for Fe, Zn and Cu, and more than 100% for Co, Mo and Mn. In particular,
the elements Ca and Na have to be added from other sources. 相似文献
986.
The paper is devoted to the phenomenon of methanogenic activity of woody debris, i.e., methane production in the course of wood decomposition by fungi, which are not directly involved in methane synthesis but form an initial link in the trophic chain leading to methanogenic archaea. Expert evaluation of probable amounts of methane emission is made. The results show that woody debris is an important global source of this greenhouse gas. 相似文献
987.
V. E. Zverev 《Russian Journal of Ecology》2009,40(4):254-260
Long-term monitoring of mountain birch populations (1992–2006) was performed in 14 test plots located at distances of 1 to 63 km from the copper-nickel smelter in Monchegorsk (Murmansk oblast) and differing in the degree of disturbance. In the period from 1999 to 2006, atmospheric emissions of sulfur dioxide and heavy metals amounted to only one-third of those between 1992 and 1998, but birch mortality in heavily polluted areas (with nickel concentrations in leaves exceeding 160 mg/kg) remained at the same level, being absent (as previously) in less polluted areas. Throughout the observation period, birch recruitment was observed only in areas where nickel concentrations in the leaves were below 160 mg/kg; i.e., this concentration proved to be the threshold with respect to both mortality and recruitment of mountain birch. The course of demographic processes in its populations has remained unchanged after the reduction of emissions, confirming the hypothesis of the “inertial“ effect of industrial emissions on ecosystems. In some areas of industrial barrens, mountain birch may perish completely within the next decade. 相似文献
988.
V. V. Tuzhilkina 《Russian Journal of Ecology》2009,40(4):227-232
To estimate the response of conifers to long-term industrial air pollution at the pigment system level, the dynamics of photosynthetic pigments have been studied in needles of Scots pine (Pinus sylvestris L.) and Siberian spruce (Picea obovata Ledeb.) growing at different distances from the emission source (a pulp and paper mill). It has been shown that the pigment apparatus of spruce. The results show that in spruce, unlike in pine, the pigment apparatus remains unchanged under the effect of weak pollution. Long-term exposure at high levels of industrial emission results in suppression of chlorophyll and carotenoid syntheses in pine but stimulates pigment production in spruce. An increase in the contents of pigments in the needles of conifers growing in the impact zone of the pulp and paper mill reflects a compensatory mechanism of adaptation of their pigment system to long-term stress exposure. 相似文献
989.
990.