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981.
Katja Osterloh Nadine Tauchnitz Oliver Spott Johannes Hepp Sabine Bernsdorf Ralph Meissner 《Wetlands Ecology and Management》2018,26(1):87-102
During the last decades, various renaturation programmes have been initialized to recover nutrient sink and ecological functions of peatlands by rewetting. Rewetting, however, often results in the formation of hotspots for methane (CH4) emissions and in temporal dieback of local vegetation. The present study aimed at quantifying changes of CH4 and nitrous oxide (N2O) emissions in a peatland currently under continuous rewetting conditions. Emissions where studied at a permanently flooded site and a non-flooded peat site with fluctuating water tables by using common closed chamber method. The permanently flooded site revealed extremely high CH4 emissions (up to 1195 mg C m?2 d?1) which were positively correlated with temperature, nutrient content, dissolved organic carbon and nitrogen concentration of the peat soil water. In contrast, the non-flooded peat site, with lower and fluctuating water tables (WT), showed significantly lower CH4 emissions and an increasing trend of CH4 release associated with a generally increasing WT caused by the progressing rewetting process. Lower N2O emissions (<24 µg N m?2 d?1) were observed at the flooded site. By contrast, the non-flooded peat site with fluctuating WT showed significantly higher N2O emissions (up to 4178 µg N m?2 d?1), in particular at high temperatures during summer time. The present results indicate that permanently flooded conditions during rewetting processes might cause higher CH4 emissions compared to fluctuating WT which in contrast might enhance N2O emissions. In total, however, no decreasing trend for CH4 emissions throughout the five-year renaturation period could be found. At least for N2O we observed a decreasing trend during rewetting. 相似文献
982.
Selenium Utilization by GPX4 Is Required to Prevent Hydroperoxide-Induced Ferroptosis 总被引:1,自引:0,他引:1
Irina Ingold Carsten Berndt Sabine Schmitt Sebastian Doll Gereon Poschmann Katalin Buday Antonella Roveri Xiaoxiao Peng Florencio Porto Freitas Tobias Seibt Lisa Mehr Michaela Aichler Axel Walch Daniel Lamp Martin Jastroch Sayuri Miyamoto Wolfgang Wurst Fulvio Ursini Marcus Conrad 《Cell》2018,172(3):409-422.e21
983.
Redescription of Tintinnopsis everta Kofoid and Campbell 1929 (Alveolata,Ciliophora, Tintinnina) Based on Taxonomic and Genetic Analyses—Discovery of a New Complex Ciliary Pattern 下载免费PDF全文
984.
Roland Loppes Nathalie Devos Sabine Willem Pascal Barthlemy Ren F. Matagne 《Journal of phycology》1996,32(2):276-278
A psychrophilic green alga belonging to the Chloromonas genus and here named ANT1 was collected in Antarctica. The activities of two enzymes, nitrate reductase and argininosuccinate lyase, were measured at various temperatures and compared to the corresponding enzyme activities in the mesophilic species Chlamydomonas reinhardtii Dangeard. For both enzymes, the temperature for apparent optimal activity was about 20°C lower in ANT1 than in C. reinhardtii. The enzymes were also submitted to various heat treatments before measuring their activities. Both psychrophilic enzymes were more sensitive to heat than the corresponding mesophilic enzymes. It is worth stressing, however, that in both species nitrate reductase was much more sensitive to heat than argininosuccinate lyase, which probably indicates that the peculiar structure of each protein primarily determines its dependence to temperature. Secondary adaptations to low temperatures should then occur to confer the psychrophilic character. 相似文献
985.
John W. Corum III Andrew J. Hartung Robin T. Stamey Sabine J. Rundle 《Plant molecular biology》1996,31(2):419-427
We have indentified a novel gene (AtB) encoding a previously uncharacterized isoform of the B regulatory subunit of the type 2A serine/threonine protein phosphatase (PP2A) of Arabidopsis, and show that mRNA derived from the AtB gene accumulates in all Arabidopsis organs. In addition, we examined the expression of the three genes encoding the A regulatory subunit of Arabidopsis PP2A and show these genes are expressed in all organs as well. Taken together, our results suggest a myriad of PP2A subunit combinations, possibly with distinct substrate specificities, may occur within each Arabidopsis cell. 相似文献
986.
Hélène Barbier-Brygoo Sabine Zimmermann Sébastien Thomine Ian R. White Paul Millner Jean Guern 《Plant Growth Regulation》1996,18(1-2):23-28
Studies of membrane electrical responses of isolated protoplasts to auxin have demonstrated the existence of elementary response chains to auxin at the plasma membrane, presently defined only by their uttermost ends. At one side, as demonstrated by several lines of evidence, the auxin perception unit involves proteins homologous to ZmER-abp1 (abp1), the most abundant auxin-binding protein from maize coleoptiles. At the other side, multiple ion transport proteins appear as targets of the auxin signal; the proton pump ATPase, an anion channel and potassium channels. We investigated early electrical responses to auxin at the plasma membrane of tobacco protoplasts. The work presented here will initially focus on abp1 and its functional role at the membrane. The C-terminus abp1 peptide (Pz151–163) was recently reported to modulate K+ currents at the plasma membrane of intact guard cells from broad bean [23] and induce plasma membrane hyperpolarisation of tobacco mesophyll protoplasts. These results further demonstrate that proteins involved in plasma membrane responses to auxin are related to maize abp1, and provide clues as to the region of the protein possibly involved in the interaction of abp1 with the plasma membrane. Secondly, this report concentrates on one of the targets of auxin, a voltage-dependent and ATP-regulated anion channel that we characterised on protoplasts from tobacco cell suspensions. This anion channel was specifically modulated by auxin, as already observed for the anion channel of guard cells [14]. Further work will be needed to assess if this auxin modulation involves a direct interaction between the hormone and the anion channel protein(s), or follows from the activation of a perception chain including abp1 homologues. 相似文献
987.
R. Huber Josef Stöhr Sabine Hohenhaus Reinhard Rachel Siegfried Burggraf Holger W. Jannasch Karl O. Stetter 《Archives of microbiology》1995,164(4):255-264
From a hydrothermal vent site off the Mexican west coast (20°50′N, 109°06′W) at a depth of 2,600 m, a novel, hyperthermophilic,
anaerobic archaeum was isolated. Cells were round to slightly irregular cocci, 1.2–2.5 μm in diameter and were motile by means
of a tuft of flagella. The new isolate grew between 60 and 93°C (optimum: 85°C), from pH 3.5 to 9 (optimum: pH 6.7), and from
0.8 to 8% NaCl (optimum: 2%). The isolate was an obligate organotroph, using chitin, yeast extract, meat extract, and peptone
for growth. Chitin was fermented to H2, CO2, NH3, acetate, and formate. H2S was formed in the presence of sulfur. The chitinoclastic enzyme system was oxygen-stable, cell-associated, and inducible
by chitin. The cell wall was composed of a surface layer of hex- americ protein complexes arranged on a p6 lattice. The core
lipids consisted of glycerol diphytanyl diethers and acyclic and cyclic glycerol diphytanyl tetraethers. The G+C content was
46.5 mol%. DNA/DNA hybridization and 16S rRNA sequencing indicated that the new isolate belongs to the genus Thermococcus, representing a new species, Thermococcus chitonophagus. The type strain is isolate GC74, DSM 10152.
Received: 8 May 1995 / Accepted: 26 June 1995 相似文献
988.
Sandrine Salmon Rémi Lemoine Aziz Jamai Sabine Bouché-Pillon Jean Christophe Fromont 《Planta》1995,197(1):76-83
The mature petiole of celery is an organ with versatile sink/source capacities where sucrose and mannitol are unloaded from and reloaded into the phloem cells. Plasma-membrane vesicles were purified by twophase partitioning either from phloem strands isolated from mature petioles of celery (Apium graveolens L.) or from mature petioles devoid of vascular bundles. Both types of vesicle were comparable in purity (more than 86% of plasma-membrane origin), size (135 nm diameter) and orientation (72% right-side-out). Plasma-membrane vesicles from phloem tissues had a higher vanadate-sensitive ATPase activity than plasma-membrane vesicles from petioles. Plasma-membrane vesicles from phloem tissues accumulated mannitol and sucrose in response to an artificial proton-motive force, in agreement with the existence of proton/substrate carriers. Plasma-membrane vesicles from petioles devoid of vascular bundles accumulated only mannitol following application of an artificial proton-motive force. The data suggest the volvement of apoplasmic transport events. The pathway for sucrose uptake in storage parenchyma cells is discussed in the light of the available physiological data. 相似文献
989.
Sabine Engemann Elke Herfurth Ulrike Briesemeister Brigitte Wittmann-Liebold 《Journal of Protein Chemistry》1995,14(4):189-195
The ribosomal protein HS23 from the 30S subunit of the extreme halophilicHaloarcula marismortui, belonging to the group of archaea, was isolated either by RP-HLPLC or two-dimensional polyacrylamide gel electrophoresis. The complete amino acid sequence was determined by automated N-terminal microsequencing. The protein consists of 123 residues with a corresponding molecular mass of 12,552 Da as determined by electrospray mass spectroscopy; the pI is 11.04. Homology studies reveal similarities to the eukaryotic ribosomal protein S8 fromHomo sapiens, Rattus norvegicus, Leishmania major, andSaccharomyces cerevisiae.Abbreviations
H. marismortui
Haloarcula marismortui
- PVDF
polyvinylidene difluoride
- PTH
phenylthiohydantoin
- RP-HPLC
reversed-phase high-performance liquid chromatography
- TFA
trifluoro acetic acid
- TP30
total protein mixture from the 30S ribosomal subunit ofH. marismortui 相似文献
990.
An Essential Role for CD44 Variant Isoforms in Epidermal Langerhans Cell and Blood Dendritic Cell Function 总被引:13,自引:0,他引:13 下载免费PDF全文
Johannes M. Weiss Jonathan Sleeman Andreas C. Renkl Henning Dittmar Christian C. Termeer Sabine Taxis Norma Howells Martin Hofmann Gabriele Khler Erwin Schpf Helmut Ponta Peter Herrlich Jan C. Simon 《The Journal of cell biology》1997,137(5):1137-1147
Upon antigen contact, epidermal Langerhans cells (LC) and dendritic cells (DC) leave peripheral organs and home to lymph nodes via the afferent lymphatic vessels and then assemble in the paracortical T cell zone and present antigen to T lymphocytes. Since splice variants of CD44 promote metastasis of certain tumors to lymph nodes, we explored the expression of CD44 proteins on migrating LC and DC. We show that upon antigen contact, LC and DC upregulate pan CD44 epitopes and epitopes encoded by variant exons v4, v5, v6, and v9. Antibodies against CD44 epitopes inhibit the emigration of LC from the epidermis, prevent binding of activated LC and DC to the T cell zones of lymph nodes, and severely inhibit their capacity to induce a delayed type hypersensitivity reaction to a skin hapten in vivo. Our results demonstrate that CD44 splice variant expression is obligatory for the migration and function of LC and DC. 相似文献