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81.
Peter Singer Manfred Wirth Ute Gerike Wolfgang Gdicke Vera Moritz 《Prostaglandins & other lipid mediators》1984,27(3):375-390
The lipid content as well as the fatty acid pattern of triglycerides, free fatty acids (FFA), phosphatidylcholine (PC) and phosphatidylethanolamine (PE) were estimated in renal cortex and medulla of spontaneously hypertensive rats (SHR) and normotensive Wistar rats (WR) at 4,8,26 and 52 weeks of age. In general, the level of triglycerides in renal medulla appeared higher when compared with the cortex. On the other hand, PC and PE, increasing with age, were usually higher in the cortex. A decreased percentage of linoleic acid (LA) in triglycerides, of arachidonic acid (AA) in PC and of eicosapentaenoic acid (EPA) in triglycerides, FFA, PC and PE could be found in the kidneys of SHR at 8 weeks of age, i.e. during the development of hypertension. This was accompanied with a rise of AA in FFA of SHR at 8 weeks of age, which occurred with delay in WR (at 26 weeks of age). From the data presented it can be concluded that systematic alterations in the availability of individual polyunsaturated fatty acids (PUFA) in various renal lipids might be related to the onset of hypertension in SHR which should be elucidated in more detail. 相似文献
82.
83.
Heinz Rotering Waltraud Fiedler Wolfgang Rollinger Volkmar Braun 《FEMS microbiology letters》1984,22(1):61-68
Abstract A mutant screening procedure is described which allows the identification of mutants carrying lesions in lipoprotein, membrane-derived oligosac-charides (MDO), and other compounds of the E. coli cell envelope containing glycerol derived from phospholipid metabolism. Two mutants lacking glycerol in MDO and one mutant devoid of lipoprotein demonstrate the usefulness of the procedure. 相似文献
84.
Hans Achenbach Werner Kohl Wolfgang Wachter Hans Reichenbach 《Archives of microbiology》1978,116(3):253-257
Besides carotenoids a complex of flexirubin-type pigments was isolated from the gliding bacteriumCytophaga johnsonae Cy j1 and separated into 6 components, which partly containe chlorine. In spite of the fact that these components still consist of pigment mixtures, the gross structures of 18 new flexirubin-type pigments could be deduced by spectroscopic and chemical investigations. The results open insights into biosynthesis and structural variety of the flexirubins, the novel non-isoprenoid pigments recently found inFlexibacter elegans.Non-Standard Abbreviations FT
Fourier transformation
- HPLC
high pressure liquid chromatography
- M+
molecular ion
- M/M
resolution of mass spectrometer
- mu
mass units
-
t
R
retention time
- TLC
thin layer chromatography
Part 16: Investigations on metabolites of microorganisms. Part. XV: H. Achenbach, W. Kohl, H. Reichenbach: Die Hauptpigmente vonCytophaga johnsonae. Tetrahedron Lett.1977, 1061. Part XIV: H. Achenbach, J. Witzke: Totalsynthese des Flexirubindimethylethers. Angew. Chem.89, 198 (1977); Angew. Chem. Int. Ed. Engl.16, 191 (1977) 相似文献
85.
86.
87.
Weed species and weed communities 总被引:3,自引:0,他引:3
Wolfgang Holzner 《Plant Ecology》1978,38(1):13-20
Summary With weeds as with many plant species the main or first level factor determining the area of distribution is a (complex) climatic one. As they have an artificially enlarged area of distribution, they have a huge border area (in an ecological sense), where the climate is not optimal for them, and where they have a narrow ecological and sociological amplitude and are especially sensitive to some measures of modern intensified agriculture. In their northern border areas species of southern origin are restricted to calcarcous substrates and to agrestal and finally ruderal communities, while in their optimal climate they are indifferent to that soil factor and able to compete with other species even in natural vegetation types. Species presumably of origin in atlantic areas are restricted with increasing continentality to very poor and acid soils, as they cannot compete with other species on better sites any more, because of their physiological properties. Thus weed distribution demonstrates the complicated reaction of plant species to the complexes of soil-climatic factors and to the competition of other species. As far as weeds are concerned, species may be only relatively calciphilous, but genuinely calcifuge species, the control being climatic in the former case and physiological in the second.The measures of modern agriculture bring about a gradual extinction of sensitive species from the limit of their range towards their centre of distribution, where they can find refuge habitats in the natural vegetation. The sensitivity of such species (also against herbicides) seems to increase towards their limits. Resistant species occur with increasing densities after the removal of their competitors. In addition, they are able to enlarge their area and to invade sites, where they had not been able to compete before, or sites where they could not previously bear the environmental conditions together with the competition of the rich weed flora.As the complex climatic gradients responsible for the ranges of weed species show smooth transitions, the alteration of species composition in weed communities is also a gradual one. This is one of the problems of weed phytosociology briefly discussed.Nomenclature follows Ehrendorfer (1973), Phytosociological units according to Westhoff & Den Held (1969).Contribution to the Symposium on Plant Species and Plant communities, held at Nijmegen, 11–12 November 1976, on the occasion of the 60th birthday of Professor Victor Westhoff.Field studies were partly supported by a grant of the Austrian Federal Ministry of Agriculture and Forestry. 相似文献
88.
Wolfgang Schmidt 《Plant Ecology》1978,36(2):105-113
Summary Starting in 1968 plant succession and nitrogen status in the top soil of an old field was investigated. The soil is a calcareous loam which was sterilized by heating. In the absence of human influence distinct successional stages with characteristic floristical and physiognomical features were observed. During the first six years vegetational development was characterized by competition between therophytes and hemicryptophytes. Agricultural treatments such as annual ploughing (spring, summer) and cutting (autumn) were found to change the trend of the succession.Five years after starting the experiment total nitrogen content in the top soil of the control area had increased slightly, while the ploughed plots persisted in their low values. A comparison of the nitrogen mineralisation between 1970 and 1974 showed decreasing amounts of mineral nitrogen in the later stage (1970: 67 kg Nmin/ha/30 weeks; 33 kg Nmin/ha/30 weeks). On the other hand, mineral nitrogen supply on the ploughed plots was not significantly different after the five-years-period. It is suggested that in old-field vegetation the external nitrogen cycle of the early therophyte stage changed to an internal one when long-lived hemicryptophytes, rhizome- and root-budding geophytes became dominant.Tables 1 to 4 show the vegetation development under different treatments; the figures represent average cover values per vegetation season using Londo's (1975) scale. Table 5 contains the total nitrogen concentration values in the uppermost of 10 cm of mineral soil, and Table 6 lists the values for soil volume, mean soil temperatures, average water content, and mineral nitrogen supplies for 1970 and 1974.
Contribution to the Symposium of the Working Group for Succession Research on Permanent Plots, held at Yerseke, the Netherlands, October 1975. 相似文献
89.
90.
Wolfgang Winkel 《Journal of Ornithology》1982,123(2):155-173
Zusammenfassung 1974–1981 wurden in einem Lärchen-Versuchsforst (320 ha; 600 künstliche Nisthöhlen) in Niedersachsen (52.27 N/7.15 E) 529 Brutvögel des Trauerschnäppers beringt. Geburtsortstreue — auf das Versuchsgebiet bezogen — konnte bei 78 Individuen (=5,2 % der ausgeflogenen Nestlinge) festgestellt werden. Die geburtsortstreuen wurden in der Regel schon im ersten Jahr als Brutvogel nachgewiesen, während die Hälfte der geburtsortstreuen bei der ersten Erfassung ein Alter von mindestens 2 Jahren besaß. In der mittleren Entfernung zwischen Geburts- und erstbekannter Bruthöhle ergab sich zwischen den Geschlechtern kein gesicherter Unterschied ( : 883 m, : 798 m). Geschwister verhielten sich bezüglich Ansiedlungsalter und Ansiedlungs-entfernung nicht einheitlich. Von den als Brutvögel beringten Trauerschnäppern konnten 38,2 % der und 24,0 % der in einem späteren Jahr wiedergefangen werden. Bei den lagen die in aufeinanderfolgenden Jahren besetzten Nisthöhlen näher beieinander als bei den (Mittelwerte: 371 m bzw. 534 m). In der untersuchten Population war in allen Jahren bei den der Prozentsatz brutortstreuer Individuen höher und der Anteil an Zuwanderern geringer als bei den (Mittelwerte: 48 % gegenüber 30 % bzw. 45 % gegenüber 64 %). Diese Befunde wurden unter anderem im Hinblick auf die Lage des Untersuchungsgebietes am Rande des Trauerschnäpper-Areals diskutiert. Die Ortstreue war geringer ausgebildet als in mehreren anderen Populationen.
Gefördert mit Hilfe von Forschungsmitteln des Landes Niedersachsen. 相似文献
On place-fidelity behaviour in the Pied Flycatcher(Ficedula hypoleuca) in the western border area of its Central European range
Summary The evaluation is based on findings from 1974 to 1981, in a 320 ha. experimental larch forest (52.27N, 7.15E), with 600 nestboxes, in western Lower Saxony, from a total of 529 breeding Pied Flycatchers. Fidelity to birthplace — recovery in the study area — was recorded for 78 individuals (=5.2 % of the fledged nestlings). faithful to birthplace were traced, as a rule, in the first year, while half of the who showed this fidelity were at least 2 years old when first recorded. There was no significant difference between sexes in the mean distance between the hole in which they were hatched and the first known breeding hole ( : 883 m, : 798 m). There was no uniformity among siblings in relation to age of settlement and distance of settlement. 38.2 % of and 24.0 % of Pied Flycatchers ringed as breeding birds were recaptured in a later year. Nest boxes occupied in successive years were closer together in the case of than (mean: 371 m and 534 m respectively). The percentage of individuals showing fidelity to birthplace was higher, in all years, and the number of immigrants smaller, in the than in (mean: 48 % against 30 % and 45 % against 64 % respectively). These findings are discussed in relation to the border situation of the study area. The rate of recoveries was lower than in some other populations.
Gefördert mit Hilfe von Forschungsmitteln des Landes Niedersachsen. 相似文献