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91.
Klaus Dose 《Journal of biological physics》1995,20(1-4):181-192
92.
The present study was conducted to investigate the effect of zinc deficiency on fatty acid desaturation in rats fed two different
types of dietary fat, a mixture of coconut oil and safflower oil (7∶1, w/w, “coconut oil diet”) or linseed oil (“linseed oil
diet”). In order to ensure an adequate food intake, all rats were force-fed by gastric tube. Zinc deficiency caused statistical
significant reducion of Δ9-desaturase activity in liver microsomes of rats fed coconut oil diet and tendencial reduction (p<0.15) in rats fed linseed oil diet compared with control rats fed diets with the same type of fat. In agreement with this
effect, zinc deficiency in the rats fed both types of dietary fat increased the ratio between total saturated and total monounsaturated
fatty in liver phospholipids and liver microsomes. Zinc deficient rats on the coconut oil diet had unchanged Δ6-desaturase
activity with linoleic acid as substrate and lowered activity with α-linolenic acid as substrate. In contrast, zinc deficient
rats on the linseed oil diet had increased Δ6-desaturase activity with linoleic acid as substrate and unchanged activity with
α-linolenic acid. Because linoleic acid is the main substrate for Δ6-desaturase in the rats fed coconut oil diet, and α-linolenic
acid is the main substrate in the rats fed linseed oil diet, it is concluded that in vivo Δ6-desaturation was not changed
by zinc deficiency in the rats fed both types of dietary fat. Activity of Δ5-desaturase was also not changed by zinc deficiency
in the rats fed both dietary fats. Levels of fatty acids in liver phospholipids and microsomes derived by Δ4-, Δ5-, and Δ6-desaturation
were not consistently changed by zinc deficiency in the rats fed both types of dietary fat. Thus, the enzyme studies and also
fatty acid composition data of liver phospholipids and microsomes indicate that zinc deficiency does not considerably disturb
desaturation of linoleic and α-linolenic acid. Therefore, it is suggested that similarities between deficiencies of zinc and
essential fatty acids described in literature are not due to disturbed desaturation of linoleic acid in zinc deficiency. The
present study also indicates that zinc deficiency enhances incorporation of eicosapentaenoic acid into phosphatidylcholine
of rats fed diets with large amounts ofn-3 polyunsaturated fatty acids. 相似文献
93.
Lars Berglund Janne Brunstedt Klaus K. Nielsen Zhaochun Chen Jørn D. Mikkelsen Kjeld A. Marcker 《Plant molecular biology》1995,27(1):211-216
A gene (Chl) encoding a novel type of chitinase was isolated from Beta vulgaris. The Ch1 protein consists of an N-terminal hydrophobic prepeptide of 25 amino acids followed by a hevein-like domain of 22 amino acid residues, an unusually long proline-rich domain of 131 amino acid residues with 90 prolines, and finally a catalytic domain of 261 amino acid residues. Proteins with similar proline-rich domains are present in some other plants. The Chl gene shows a transient expression in response to fungal infection. 相似文献
94.
95.
Klaus Peter Zulka Norbert Milasowszky Christa Lethmayer 《Biodiversity and Conservation》1997,6(1):75-88
To assess the biodiversity potential of an ungrazed and a grazed inland salt meadow in the Seewinkel (Eastern Austria), spider assemblages were recorded by pitfall trapping for 1 year. Both species assemblages consisted, to a large extent, of rare species of conservation interest. The species assemblage of the grazed site was dominated by Pardosa agrestis, but highly specific halotopobiontic species also occurred in higher numbers. Halotolerant species were also present in the ungrazed meadow, but their individual number was much lower. The species composition of this site reflects the more balanced microclimatical situation of the high sward. Comparison of the two assemblages with 207 other meadow spider assemblages of Central Europe shows a separated position, especially of the grazed site assemblage. High similarities with assemblages of meadows with a similar vegetation structure indicate a high importance of management. Considering the high proportion of rare species on both sites, the best management of the salt meadow and pan shores of the Seewinkel should combine areas of light grazing with ungrazed areas. However, the proportion of these parts and the intensity of grazing still remains to be determined by quantitative experiments. 相似文献
96.
In heterotrophic cell suspensions of sunflower (Helianthus annuusL. cv. Spanners Allzweck) the effect of Pmg elicitor, a fungalelicitor preparation from Phytophthora megasperma f. sp. glycinea,on the induction of chitinase and ß-1,3-glucanaseactivity was studied in relation to changes in ethylene biosynthesis.Dose-response experiments with Pmg elicitor showed that theonset of the induction of intracellular chitinase and ß-1,3-glucanaseactivity coincided or followed a transient rise in ethyleneand particularly endogenous 1-aminocyclopropane-1-carboxylicacid (ACC) levels within 5 h of application. Treatment with5 µg ml1 elicitor stimulated ethylene and ACC levels1.6-fold and 4-fold, relative to control, respectively. Themolar ratio of ACC to ethylene changed from approximately 3:1in controls to 9:1 in treated cells. During further incubation,ethylene formation and, to a lesser degree, ACC levels declinedand the ACC/ethylene ratio increased to 56:1 in elicitor-treatedcells. On a protein basis, the activities of ß-1,3-glucanaseand chitinase increased approximately 5-fold and 8-fold, respectively,48 h after elicitor application. Additional treatment with theACC synthesis inhibitor aminoethoxyvinyiglycine (AVG) decreasedelicitor-induced enzyme activities and the levels of both ethyleneand ACC. Elicitor effects on chitinase and ß-1,3-glucanaseactivities could be fully restored when ACC was additionallyapplied. Concomitantly, the ACC/ ethylene ratio increased. Neithertreatments with ACC alone, which simultaneously increased internalACC and ethylene levels, nor treatments with AVG alone, whichsimultaneously reduced ACC and ethylene levels, could generallystimulate chitinase or ß-1,3-glucanase activitiesin the cells. It is suggested that ACC functions as a promotingfactor in the induction of chitinase and ß-1,3-glucanaseactivity triggered by Pmg elicitor and appears to reverse aninhibiting influence of ethylene. Key words: 1-Aminocyclopropane-1-carboxylic acid, chitinase, ß-1,3-glucanase, ethylene, Helianthus cellsuspension cultures, Phytophthora megasperma-elicitor 相似文献
97.
The evolutionary relationship of muscle and nonmuscle actin isoforms in deuterostomia was studied by the isolation and characterization
of two actin genes from the cephalochordate Branchiostoma lanceolatum and two from the hemichordate Saccoglossus kowalevskii The Branchiostoma genes specify a muscle and a nonmuscle actin type, respectively. Together with earlier results on muscle actins from vertebrates
and urochordates, a N-terminal sequence signature is defined for chordate muscle actins. These diagnostic amino acid residues
separate the chordates from the echinoderms and other metazoa. Although the two Saccoglossus actins characterized so far lack the diagnostic residues, in line with the presumptive phylogenetic position of hemichordates
outside the chordates, a definitive conclusion can only be expected once the full complement of actin genes of Saccoglossus is established. Comparison of the intron patterns of the various deuterostomic actin genes shows that intron 330-3, which
is present in all vertebrate genes, is conspicuously absent from nonvertebrate genes. The possible origin of this intron is
discussed.
Received: 4 July 1997 / Accepted: 29 August 1997 相似文献
98.
Klaus Lunau 《Plant Systematics and Evolution》1995,198(3-4):235-252
The spectral reflection of pollen in 67 plant species out of 28 families was measured by means of mass recording of pollen grains. Various types of spectral reflection curves were found, but 75% belonged to two categories: 1. Human-yellow pollen with strong reflection in the green and red, and low reflection in the ultraviolet and blue range of wavelengths. 2. Human-whitish pollen with strong reflection in the green and red and additional reflection of shorter wavelengths. It is shown that it is important to have information about the mode of the visual pollen display — crypsis or colour contrast against the corolla, pollen advertisement, or concealment — and the visual capabilities of the presumed pollinators in order to be able to discuss the signalling function of pollen colours. 相似文献
99.
Summary We have introduced the gene encoding luciferase from Photinus pyralis into pear and tobacco cells in order to judge the reaction of plant tissue to damaging conditions such as incubation at high temperature or inoculation with a pathogen. The constitutive expression of the luciferase gene via a strong promoter slowly decreased during propagation of the transformed pear cell line. After various stress treatments the resulting luciferase activity and the ATP content of the plant cells were determined by bioluminescence and found to correspond to each other. Inoculation of transformed pear cells with Erwinia amylovora resulted in a continuous decrease of luciferase activity in contrast to tobacco cells, where the enzyme activity was significantly higher in the first period after inoculation with bacteria compared to the untreated control cells. The pattern of the luciferase activity reflected the slow damage of the host-plant cells by E. amylovora and the elevated metabolism of the non-host cells after inoculation with the pathogen.Abbreviations 2,4-D
2,4-dichloro-phenoxyacetic acid
- CaMV
Cauliflower mosaic virus
- DTT
dithiothreitol
- EDTA
ethylenediaminetetraacetate
- FDA
fluorescein diacetate
- HEPES
(hydroxyethyl)piperazine(ethanesulfonic acid)
- HR
hypersensitive reaction
- Tris
tris (hydroxymethyl)amino-methane 相似文献
100.
Rainer Scharf Malte Meesmann Jan Boese Dante R. Chialvo Klaus -D. Kniffki 《Biological cybernetics》1995,73(3):255-263
Counting statistics in the form of the variance-time curve provides an alternative to spectral analysis for point processes exhibiting 1/f β-fluctuations, such as the heart beat. However, this is true only for β<1. Here, the case of general β is considered. To that end, the mathematical relation between the variance-time curve and power spectral density in the presence of 1/f β-noise is worked out in detail. A modified version of the variance-time curve is presented, which allows us to deal also with the case β?1. Some applications to the analysis of heart rate variability are given. 相似文献