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991.
Large‐scale disturbance legacies and the climate sensitivity of primary Picea abies forests
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Jonathan S. Schurman Radek Bače Vojtěch Čada Shawn Fraver Pavel Janda Dominik Kulakowski Jana Labusova Martin Mikoláš Thomas A. Nagel Rupert Seidl Michal Synek Kristýna Svobodová Oleh Chaskovskyy Marius Teodosiu Miroslav Svoboda 《Global Change Biology》2018,24(5):2169-2181
Determining the drivers of shifting forest disturbance rates remains a pressing global change issue. Large‐scale forest dynamics are commonly assumed to be climate driven, but appropriately scaled disturbance histories are rarely available to assess how disturbance legacies alter subsequent disturbance rates and the climate sensitivity of disturbance. We compiled multiple tree ring‐based disturbance histories from primary Picea abies forest fragments distributed throughout five European landscapes spanning the Bohemian Forest and the Carpathian Mountains. The regional chronology includes 11,595 tree cores, with ring dates spanning the years 1750–2000, collected from 560 inventory plots in 37 stands distributed across a 1,000 km geographic gradient, amounting to the largest disturbance chronology yet constructed in Europe. Decadal disturbance rates varied significantly through time and declined after 1920, resulting in widespread increases in canopy tree age. Approximately 75% of current canopy area recruited prior to 1900. Long‐term disturbance patterns were compared to an historical drought reconstruction, and further linked to spatial variation in stand structure and contemporary disturbance patterns derived from LANDSAT imagery. Historically, decadal Palmer drought severity index minima corresponded to higher rates of canopy removal. The severity of contemporary disturbances increased with each stand's estimated time since last major disturbance, increased with mean diameter, and declined with increasing within‐stand structural variability. Reconstructed spatial patterns suggest that high small‐scale structural variability has historically acted to reduce large‐scale susceptibility and climate sensitivity of disturbance. Reduced disturbance rates since 1920, a potential legacy of high 19th century disturbance rates, have contributed to a recent region‐wide increase in disturbance susceptibility. Increasingly common high‐severity disturbances throughout primary Picea forests of Central Europe should be reinterpreted in light of both legacy effects (resulting in increased susceptibility) and climate change (resulting in increased exposure to extreme events). 相似文献
992.
Davor Miličić 《Protoplasma》1957,48(1):170-171
Ohne ZusammenfassungDie vorliegenden Versuehe wurden während meines kurzen Aufenthalts im Pflanzenphysiologisehen Institut der Universität Wien ausgeführt. Herrn Prof. Dr. Karl Höfler und Herrn Dr. H. Kinzel danke ich sehönstens auch an dieser Stelle für die Untersfützung während der Arbeit. 相似文献
993.
Beranič N Brožič P Brus B Sosič I Gobec S Lanišnik Rižner T 《The Journal of steroid biochemistry and molecular biology》2012,130(1-2):16-25
The human aldo-keto reductase AKR1C2 converts 5α-dihydrotestosterone to the less active 3α-androstanediol and has a minor 20-ketosteroid reductase activity that metabolises progesterone to 20α-hydroxyprogesterone. AKR1C2 is expressed in different peripheral tissues, but its role in uterine diseases like endometriosis has not been studied in detail. Some progestins used for treatment of endometriosis inhibit AKR1C1 and AKR1C3, with unknown effects on AKR1C2. In this study we investigated expression of AKR1C2 in the model cell lines of peritoneal endometriosis, and examined the ability of recombinant AKR1C2 to metabolise progesterone and progestin dydrogesterone, as well as its potential inhibition by progestins. AKR1C2 is expressed in epithelial and stromal endometriotic cell lines at the mRNA level. The recombinant enzyme catalyses reduction of progesterone to 20α-hydroxyprogesterone with a 10-fold lower catalytic efficiency than the major 20-ketosteroid reductase, AKR1C1. AKR1C2 also metabolises progestin dydrogesterone to its 20α-dihydrodydrogesterone, with 8.6-fold higher catalytic efficiency than 5α-dihydrotestosterone. Among the progestins that are currently used for treatment of endometriosis, dydrogesterone, medroxyprogesterone acetate and 20α-dihydrodydrogesterone act as AKR1C2 inhibitors with low μM K(i) values in vitro. Their potential in vivo effects should be further studied. 相似文献
994.
M. Pěčková 《Folia microbiologica》1991,36(6):515-521
A bacterial strain belonging to the speciesThermus was isolated from the water of a Carlsbad hot spring at 70–73°C. The microorganism can grow aerobically and forms yellow
and orange colonies on a special medium, due to a carotenoid pigment. The growth optimum is 70–75°C. The minimum and maximum
temperatures for growth are 40 and 80°C, respectively. The microorganism is a Gram-negative, rod-like, immobile bacterium,
its characteristic feature being the ability to form long filaments (up to 200 μm long). The content of guanine and cytosine
in DNA is 65.1 %. This rare endemic microorganism was isolated and described in detail in Czechoslovakia for the first time.
It was included in theCzechoslovak Collection of Microorganisms of the Masaryk University in Brno and is available under the catalog number of CCM 4167.
Translated by Č. Novotny 相似文献
995.
996.
997.
The complete amino acid sequence of apolipophorin-III (apoLp-III), a lipid-binding hemolymph protein from the greater wax
moth,Galleria mellonella, was determined by protein sequencing. The mature protein consists of 163 amino acid residues forming a protein of 18,075.5
Da. Its sequence is similar to apoLp-III from other Lepidopteran species, but remarkably different from the apoLp-IIIs of
insects from other orders. As shown by mass spectrometric analysis, the protein carries no modifications. Thus, all of its
known physiological functions, including its recently discovered immune response-stimulating activity, must reside in the
protein itself. 相似文献
998.
B. Zelić N. Pavlović V. Delić D. Vasić-Rački 《Bioprocess and biosystems engineering》1999,21(1):45-50
Summary A simple unstructured mathematical model for the oxidation of glucose to 2,5-diketo-D-gluconic acid with Erwinia citreus was developed. The kinetic parameters of the model were estimated by the oxygen partial pressure method and directly from the temporal response obtained from the experimental data collected in the batch fermentation. The simple developed model based on the kinetic measurements was able to simulate quite well the dynamic behaviour of the batch fermentation. 相似文献
999.
Prof. Dr. Josip Tišljar M.Sc. Igor Vlahović Dr. Ivo Velić Dr. Dubravko Matičec Dr. Julie Robson 《Facies》1998,38(1):137-151
Summary During the Late Albian, Early and Middle Cenomanian in the NW part of the Adriatic Carbonate Platform (presentday Istria)
specific depositional systems characterised by frequent lateral and vertical facies variations were established within a formerly
homogeneous area, ranging from peritidal and barrier bars to the offshore-transition zone. In southern Istria this period
is represented by the following succession: thin-bedded peritidal peloidal and stromatolitic limestones (Upper Albian); well-bedded
foreshore to shoreface packstones/grainstones with synsedimentary dliding and slumping (Vraconian-lowermost Cenomanian); shoreface
to off-shore storm-generated limestones (Lower Cenomanian); massive off-shore to shoreface carbonate sand bodies (Lower Cenomanian);
prograding rudist bioclastic subaqueous dunes (Lower to Middle Cenomanian); rudist biostromes (Lower to Middle Cenomanian),
and high-energy rudist and ostreid coquina beds within skeletal wackestones/packstones (Middle Cenomanian).
Rapid changes of depositional systems near the Albian/Cenomanian transition in Istria are mainly the result of synsedimentary
tectonics and the establishment of extensive rudist colonies producing enormous quantities of bioclastic material rather than
the influence of eustatic changes. Tectonism is evidenced by the occurrence of sliding scars, slumps, small-scale synsedimentary
faults and conspicuous bathymetric changes in formerly corresponding environments. Consequently, during the Early Cenomanian
in the region of southern Istria, a deepening of the sedimentary environments occurred towards the SE, resulting in the establishment
of a carbonate ramp system. Deeper parts of the ramp were below fair-weather wave base (FWWB), while the shallower parts were
characterised by high-energy environments with extensive rudist colonies, and high organic production leading to the progradation
of bioclastic subaqueous dunes. This resulted in numerous shallowing- and coarsening-upwards clinostratified sequences completely
infilling formerly deeper environments, and the final re-establishment of the shallow-water environments over the entire area
during the Middle Cenomanian. 相似文献
1000.
Metabolism of polychlorinated biphenyls by Solanum nigrum hairy root clone SNC-9O and analysis of transformation products 总被引:1,自引:0,他引:1
Kučerová Petra Macková Martina Chromá Ludmila Burkhard Jiri Tríska Jan Demnerová Katerina Macek Tomáš 《Plant and Soil》2000,225(1-2):109-115
The study investigates aspects of PCB metabolism by a hairy root culture of Solanum nigrum L. (clone SNC-9O) in vitro. Standard conditions were established for efficient, up to 72% PCB conversion (22 individual PCB congeners examined in commercial
mixture Delor 103, 5 g fresh biomass in 100 ml media shaken with 5 mg PCB for 14 days). The conversion products formed from
three monochlorobiphenyls were monohydroxychlorobiphenyls and dihydroxychlorobiphenyls, while six dichlorobiphenyls yielded
different monohydroxydichlorobiphenyls. Efficiency of the transformation of individual PCB congeners was evaluated together
with phytotoxic effect on the clone SNC-9O. Major metabolites of monochlorobiphenyls analysed after extraction from biomass
were hydroxylated at the position 4, and 4′, respectively.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献