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1.
Pavel Husák 《Folia Geobotanica》1982,17(4):421-426
Scattered green was studied in Czechoslovakia by means of the air multispectral photography and of the field observation. According to various repartition and canopy 19 structural types of seattered green were derived. 相似文献
2.
Pavel Kovář 《Folia Geobotanica》1990,25(4):407-430
Up-to-date crop production concentrates on the maximisation of plant matter production, both by optimum utilization of solar energy by plants and by the application of additional energy. Therefore a natural strategy is being developed aimed at combining the physiological functions of the assimilation organs with their external shaping and strengthening their variety in space and area. As demonstrated by many deposition studies, this effect is contradictory to the factors conditioning the low deposition capacity of plant covers. A high level of particle, gas and solution deposition increases the danger of food chain contamination and has a negative impact on plant production. Data concentrated on transport values of pollutants and their long-term dynamics in stands could be used for the selection of ideal crop types; therefore every effort should be directed towards selection and breeding. 相似文献
3.
Lipid Composition in Scrapie-Infected Mouse Brain: Prion Infection Increases the Levels of Dolichyl Phosphate and Ubiquinone 总被引:1,自引:0,他引:1
Zhizhong Guan Magnus Söderberg Pavel Sindelar Stanley B. Prusiner †Krister Kristensson Gustav Dallner 《Journal of neurochemistry》1996,66(1):277-285
Abstract: The neutral and phospholipid composition of mouse brain infected with scrapie prions was investigated. During the later stages of this disease, the level of dolichol decreased by 30% whereas the level of dolichyl phosphate increased by 30%. In terminally ill mice, there was also a 2.5-fold increase in both total ubiquinone and its reduced form. Furthermore, α-tocopherol was elevated at this stage by 50%. In contrast, no changes were observed in phospholipid amount, in phospholipid composition, and in phosphatidylethanolamine plasmalogen content during the entire disease process. The fatty acid and aldehyde composition of individual phospholipids remained unaltered as well. No modifications could be detected in cholesterol content. Thus, the majority of membrane lipids in scrapie-infected mouse brain are modified in neither quantity nor structure, but specific changes occur to a few polyisoprenoid lipids. This specificity indicates that, although prions accumulate in lysosomes, the infection process is not associated with a general membrane destruction caused by lysosomal enzyme leakage. 相似文献
4.
Jan Raška Kateřina Chalušová Jan Krajiček Radomír Čabala Zuzana Bosáková Pavel Štys Alice Exnerová 《Journal of evolutionary biology》2023,36(7):1050-1064
Many prey species change their antipredator defence during ontogeny, which may be connected to different potential predators over the life cycle of the prey. To test this hypothesis, we compared reactions of two predator taxa – spiders and birds – to larvae and adults of two invasive true bug species, Oxycarenus hyalinipennis and Oxycarenus lavaterae (Heteroptera: Oxycarenidae) with life-stage-specific chemical defence mechanisms. The reactions to larvae and adults of both true bug species strikingly differed between the two predator taxa. The spiders were deterred by the defences of adult bugs, but the larval defences were ineffective against them. By contrast, birds attacked the larvae considerably less often than the adult bugs. The results indicate a predator-specific ontogenetic change in defence effectiveness of both Oxycarenus species. The change in defence is likely linked to the life-stage-specific composition of secretions in both species: whereas secretions of larvae are dominated by unsaturated aldehydes, secretions of adults are rich in terpenoids, which probably serve dual function of defensive chemicals and pheromones. Our results highlight the variation in defence between different life stages and the importance of testing responses of different types of predators. 相似文献
5.
M. Nováková Beat M. Riederer Vladmír Viklický Pavel Dráber 《Histochemistry and cell biology》1997,107(4):337-344
A panel of monoclonal antibodies specific of α-tubulin (TU-01, TU-09) and β-tubulin (TU-06, TU-13) subunits was used to study
the location of N-terminal structural domains of tubulin in adult mouse brain. The specificity of antibodies was confirmed
b immunoblotting experiments. Immunohistochemical staining of vibratome sections from cerebral cortex, cerebellum, hippocampus,
and corpus callosum showed that antibodies TU-01, TU-09, and TU13 reacted with neuronal and glial cells and their processes,
whereas the TU-06 antibody stained only the perikarya. Dendrites and axons were either unstained or their staining was very
weak. As the TU-06 epitope is located on the N-terminal structural domain of β-tubulin, the observed staining pattern cannot
be interpreted as evidence of a distinct subcellular localization of β-tubulin isotypes or known post-translational modifications.
The limited distribution of the epitope could, rather, reflect differences between the conformations of tubulin molecules
in microtubules of somata and neurites or, alternatively, a specific masking of the corresponding region on the N-terminal
domain of β-tubulin by interacting protein(s) in dendrites and axons.
Accepted: 11 November 1996 相似文献
6.
7.
S. Pavel F.A.J. Muskiet G.T. Nagel Z. Schwippelov J. Ducho 《Journal of chromatography. B, Analytical technologies in the biomedical and life sciences》1981,222(3):329-336
The isolation of two Thormählen-positive compounds from the urine of a patient with malignant melanoma and the elucidation of their structure by gas chromatography—mass spectrometry is described. The compounds were isolated using a poly-N-vinylpyrrolidone column and separated by preparative thin-layer chromatography. After elution they were analyzed by gas chromatography and gas chromatography—mass spectrometry as their trimethylsilyl derivatives and after hydrolysis also as their tert.-butyldimethylsilyl derivatives. The results showed the main Thormählen-positive compound A to be the glucuronide of 5-hydroxy-6-methoxyindole, whereas the minor compound AX appeared to be the glucuronide of its isomer 6-hydroxy-5-methoxyindole. 相似文献
8.
Pavel Hrako 《American journal of physical anthropology》1975,43(2):243-244
This paper presents the first data in the alpha-amylase isoenzymes in primates of the families: Lemuridae, Cebidae, Cercopithecidae, Hylobatidae and Pongidae. By means of agar-gel electrophoresis of urine samples from 33 individuals belonging to ten species of the above mentioned families a total of 14 different variants of amylase heterogeneity were found. 相似文献
9.
Katarína Nemjová Jiří Neustupa Jan Št'astný Pavel Škaloud Jana Veselá 《Phycological Research》2011,59(3):208-220
The morphological and molecular differentiation of the Micrasterias truncata (Corda) ex Bréb species complex was investigated. In total, 17 strains traditionally assigned to M. truncata were isolated from different European localities (Czech Republic, southwest France, Ireland), and obtained from public culture collections. In addition, strains of the morphologically similar species, M. decemdentata (Nägeli) W. Archer and M. zeylanica F. E. Fritsch, were also included. Molecular phylogenetic analysis based on trnGucc intron sequences revealed five well supported clades. Two Australian strains assigned to M. truncata var. pusilla G. S. West formed a lineage sister to M. zeylanica. This was evident from a concatenated phylogeny based on small subunit rDNA and trnGucc intron sequences. The isolated position of these strains was also illustrated by parallel landmark‐based geometric morphometric analysis of cell shapes. The strains NIES 783 and NIES 784 probably represent a separate species. Particular analysis, including additional strains, is needed to resolve the relationship inside this lineage. The second phylogenetic lineage, containing two strains of M. truncata var. semiradiata (Kützing) Wolle, was also different from other strains on the basis of morphometric data. We suggest recognizing this variety as a separate species, Micrasterias semiradiata L.A. Brébisson ex F. T. Kützing. The remaining three clades formed a firmly supported group of the ‘core’M. truncata recognized by both molecular markers. However, neither any morphological, morphometric, nor geographical pattern was detected among members of these three clades. This pattern could be caused by a relatively recent origin of these lineages that may represent a sympatric, truly cryptic species. Strains attributable to traditional morphologically defined variety M. truncata var. neodamensis were nested within the ‘core’M. truncata. 相似文献
10.
Cyanobacterial communities of the splash zone of two Croatian islands, Veruda and Ugljan, were surveyed. At each island, we studied eight localities with different aspects. From all 336 samples, a total of 42 cyanobacterial species, one green alga, and one red alga were found. In both islands Hyella spp. and Gloeocapsopsis crepidinum dominated and Entophysalis deusta, Solentia spp., Kyrtuthrix dalmatica and Mastigocoleus testarum were found frequently. Multivariate statistical analysis of species composition shows that the vertical gradient is the strongest determinant of species composition and that there are statistically significant but not very pronounced differences in species composition between the two islands. Species composition among individual sites within islands differed slightly, and between localities decreased rather slowly with the distance of individual samples (i.e. the similarity distance decay was very slow), showing that even close samples can have quite different species composition. The species accumulation curves do not reach their asymptote, indicating that many samples are needed to reasonably cover the species richness of a site. This study highlights the importance of in-depth species counts and high density sampling along vertical gradients for satisfactory cyanobacterial community assessments in marine coastal splash zones. 相似文献