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131.
Mahler H Wuennenberg P Linder M Przybyla D Zoerb C Landgraf F Forreiter C 《Planta》2007,225(5):1073-1083
Singlet oxygen is reported to have the most potent damaging effect upon the photosynthetic machinery. Usually this reactive
oxygen molecule acts in concert with other ROS types under stressful conditions. To understand the specific role of singlet
oxygen we took advantage of the conditional flu mutant of Arabidopsis thaliana. In flu, the negative feedback loop is abolished, which blocks chlorophyll biosynthesis in the dark. Therefore high amounts of free
protochlorophyllide accumulate during darkness. If flu gets subsequently illuminated, free protochlorophyllide acts as a photosensitiser leading almost exclusively to high amounts
of 1O2. Analysing the thylakoid protein pattern by using 2D PAGE and subsequent MALDI-TOF analysis, we could show, in addition to
previous described effects on photosystem II, that singlet oxygen has a massive impact on the thylakoid ATP synthase, especially
on its γ subunit. Additionally, it could be shown that the activity of the ATP synthase is reduced upon singlet oxygen exposure
and that the rate of non-photochemical quenching is affected in flu mutants exposed to 1O2. 相似文献
132.
Plants constantly adapt their leaf orientation in response to fluctuations in the environment, to maintain radiation use efficiency in the face of varying intensity and incidence direction of sunlight. Various methods exist for measuring structural canopy parameters such as leaf angle distribution. However, direct methods tend to be labour-intensive, while indirect methods usually give statistical information on stand level rather than on individual leaves. We present an area-based, binocular stereo system composed of commercially available components that allows three-dimensional reconstruction of small- to medium-sized canopies on the level of single leaves under field conditions. Spatial orientation of single leaves is computed with automated processes using modern, well-established stereo matching and segmentation techniques, which were adapted for the properties of plant canopies, providing high spatial and temporal resolution (angle measurements with an accuracy of approx. +/-5 degrees and a maximum sampling rate of three frames per second). The applicability of our approach is demonstrated in three case studies: (1) the dihedral leaflet angle of an individual soybean was tracked to monitor nocturnal and daytime leaf movement showing different frequencies and amplitudes; (2) drought stress was diagnosed in soybean by quantifying changes in the zenith leaflet angle distribution; and (3) the diurnal course of the zenith leaf angle distribution of a closed soybean canopy was measured. 相似文献
133.
134.
Lack of Electricity Production by Pelobacter carbinolicus Indicates that the Capacity for Fe(III) Oxide Reduction Does Not Necessarily Confer Electron Transfer Ability to Fuel Cell Anodes
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Hanno Richter Martin Lanthier Kelly P. Nevin Derek R. Lovley 《Applied microbiology》2007,73(16):5347-5353
The ability of Pelobacter carbinolicus to oxidize electron donors with electron transfer to the anodes of microbial fuel cells was evaluated because microorganisms closely related to Pelobacter species are generally abundant on the anodes of microbial fuel cells harvesting electricity from aquatic sediments. P. carbinolicus could not produce current in a microbial fuel cell with electron donors which support Fe(III) oxide reduction by this organism. Current was produced using a coculture of P. carbinolicus and Geobacter sulfurreducens with ethanol as the fuel. Ethanol consumption was associated with the transitory accumulation of acetate and hydrogen. G. sulfurreducens alone could not metabolize ethanol, suggesting that P. carbinolicus grew in the fuel cell by converting ethanol to hydrogen and acetate, which G. sulfurreducens oxidized with electron transfer to the anode. Up to 83% of the electrons available in ethanol were recovered as electricity and in the metabolic intermediate acetate. Hydrogen consumption by G. sulfurreducens was important for ethanol metabolism by P. carbinolicus. Confocal microscopy and analysis of 16S rRNA genes revealed that half of the cells growing on the anode surface were P. carbinolicus, but there was a nearly equal number of planktonic cells of P. carbinolicus. In contrast, G. sulfurreducens was primarily attached to the anode. P. carbinolicus represents the first Fe(III) oxide-reducing microorganism found to be unable to produce current in a microbial fuel cell, providing the first suggestion that the mechanisms for extracellular electron transfer to Fe(III) oxides and fuel cell anodes may be different. 相似文献
135.
Cucurbitaceae contain c. 800 species in 130 genera and are among the economically most important families of plants. We inferred their phylogeny based on chloroplast DNA sequences from two genes, one intron, and two spacers (rbcL, matK, trnL, trnL-trnF, rpl20-rps12) obtained for 171 species in 123 genera. Molecular data weakly support the traditional subfamilies Cucurbitoideae (111 genera) and Nhandiroboideae (19 genera, 60 species), and recover most of the eleven tribes, but almost none of the subtribes. Indofevillea khasiana is sister to all other Cucurbitoideae, and the genera of Joliffieae plus a few Trichosantheae form a grade near the base of Cucurbitoideae. A newly discovered large clade consists of the ancestrally Asian genera Nothoalsomitra, Luffa, Gymnopetalum, Hodgsonia, Trichosanthes, and the New World tribe Sicyeae. Genera that are poly- or paraphyletic include Ampelosicyos, Cucumis, Ibervillea, Neoachmandra, Psiguria, Trichosanthes, and Xerosicyos. Flower characters, especially number of free styles, fusion of filaments and/or anthers, tendril type, and pollen size, exine, and aperture number correlate well with the chloroplast phylogeny, while petal and fruit characters as well as karyotype exhibit much evolutionary flexibility. 相似文献
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137.
Using multiplexed quantitative proteomics, we analyzed cell cycle‐dependent changes of the human proteome. We identified >4,400 proteins, each with a six‐point abundance profile across the cell cycle. Hypothesizing that proteins with similar abundance profiles are co‐regulated, we clustered the proteins with abundance profiles most similar to known Anaphase‐Promoting Complex/Cyclosome (APC/C) substrates to identify additional putative APC/C substrates. This protein profile similarity screening (PPSS) analysis resulted in a shortlist enriched in kinases and kinesins. Biochemical studies on the kinesins confirmed KIFC1, KIF18A, KIF2C, and KIF4A as APC/C substrates. Furthermore, we showed that the APC/CCDH1‐dependent degradation of KIFC1 regulates the bipolar spindle formation and proper cell division. A targeted quantitative proteomics experiment showed that KIFC1 degradation is modulated by a stabilizing CDK1‐dependent phosphorylation site within the degradation motif of KIFC1. The regulation of KIFC1 (de‐)phosphorylation and degradation provides insights into the fidelity and proper ordering of substrate degradation by the APC/C during mitosis. 相似文献
138.
We introduce a mass spectrometry-based method that provides residue-resolved quantitative information about protein phosphorylation. In this assay we combined our full-length expressed stable isotope-labeled protein for quantification strategy (FLEXIQuant) with a traditional kinase assay to determine the mechanisms of multikinase substrate phosphorylation such as priming-dependent kinase activities. The assay monitors the decrease in signal intensity of the substrate peptides and the concomitant increase in the (n × 80 Da)-shifted phosphorylated peptide. We analyzed the c-Jun N-terminal kinase (JNK)-dependent glycogen synthase kinase 3β (GSK3β) activity on doublecortin (DCX) revealing mechanistic details about the role of phosphorylation cross-talk in GSK3β activity and permitting an advanced model for GSK3β-mediated signaling. 相似文献
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140.
F van Hoorn ME Campian A Spijkerboer MT Blom RN Planken AC van Rossum JM de Bakker AA Wilde M Groenink HL Tan 《PloS one》2012,7(8):e42037