Search results for "magnetic [charge]"
showing 10 items of 6136 documents
Photoprotection dynamics observed at leaf level from fast temporal reflectance changes
2018
Vegetation dynamically reacts to the available photosynthetically active radiation (PAR) by adjusting the photosynthetic apparatus to either a light harvesting or a photoprotective modus. When activating the photoprotection mechanism, either minor or major pigment-protein interactions may occur at the leaf level, resulting in different light absorption and consequently reflectance intensities. The reflectance changes were measured during sudden illumination transients designed to provoke fast adaptation to high irradiance. Different spectral reflectance change features were observed during different stages of photoprotection activation, extending over part of the visible spectral range (i.e…
Rigid Core and Flexible Terminus
2012
The structure of the major light-harvesting chlorophyll a/b complex (LHCII) was analyzed by pulsed EPR measurements and compared with the crystal structure. Site-specific spin labeling of the recombinant protein allowed the measurement of distance distributions over several intra- and intermolecular distances in monomeric and trimeric LHCII, yielding information on the protein structure and its local flexibility. A spin label rotamer library based on a molecular dynamics simulation was used to take the local mobility of spin labels into account. The core of LHCII in solution adopts a structure very similar or identical to the one seen in crystallized LHCII trimers with little motional freed…
Monitoring of transglutaminase crosslinking reaction by 1H NMR spectroscopy on model substrates
2015
International audience; A new method based on 1H NMR spectroscopy was developed for monitoring transglutaminase crosslinking reaction with model molecules (CBZ-Gln-Gly and N-α-acetyl-lysine). The transglutaminase reaction led to the appearance of new resonances on NMR spectrum as well as significant decrease in others. The new observed resonances, originated from newly formed ɛ-(γ-glutamyl)lysine isopeptide bonds, evidence the enzymatic reaction and allow to quantify the ɛ-(γ-glutamyl)lysine fragment. Moreover, the decrease in resonance intensity, originated from lysine, permit to determine the crosslinking degree. These results obtained by 1H NMR spectroscopy can be used as an alternative …
Phytotoxic Metabolites Isolated from Neufusicoccum batangarum, the Causal Agent of the Scabby Canker of Cactus Pear (Opuntia ficus-indica L.)
2020
Six phytotoxins were obtained from the culture filtrates of the ascomycete Neofusicoccum batangarum, the causal agent of the scabby canker of cactus pear (Opuntia ficus-indica L.) in minor Sicily islands. The phytotoxins were identified as (&minus
Primary production calculations for sea ice from bio-optical observations in the Baltic Sea
2016
Abstract Bio-optics is a powerful approach for estimating photosynthesis rates, but has seldom been applied to sea ice, where measuring photosynthesis is a challenge. We measured absorption coefficients of chromophoric dissolved organic matter (CDOM), algae, and non-algal particles along with solar radiation, albedo and transmittance at four sea-ice stations in the Gulf of Finland, Baltic Sea. This unique compilation of optical and biological data for Baltic Sea ice was used to build a radiative transfer model describing the light field and the light absorption by algae in 1-cm increments. The maximum quantum yields and photoadaptation of photosynthesis were determined from 14C-incorporatio…
Cytosolic pH regulates root water transport during anoxic stress through gating of aquaporins.
2003
Flooding of soils results in acute oxygen deprivation (anoxia) of plant roots during winter in temperate latitudes, or after irrigation1, and is a major problem for agriculture. One early response of plants to anoxia and other environmental stresses is downregulation of water uptake due to inhibition of the water permeability (hydraulic conductivity) of roots (Lpr)2,3,4,5. Root water uptake is mediated largely by water channel proteins (aquaporins) of the plasma membrane intrinsic protein (PIP) subgroup6,7,8. These aquaporins may mediate stress-induced inhibition of Lpr2,4,9 but the mechanisms involved are unknown. Here we delineate the whole-root and cell bases for inhibition of water upta…
Oxygen transmittance correction for solar-induced chlorophyll fluorescence measured on proximal sensing: Application to the NASA-GSFC fusion tower
2017
Since oxygen (O 2 ) absorption of light becomes more pronounced at higher pressure levels, even a few meters distance between the target and the sensor can strongly affect canopy-leaving Solar-Induced chlorophyll Fluorescence (SIF) retrievals. This study was conducted to quantify the consequent error propagation and the impact of ignoring oxygen absorption effects on proximal sensing SIF measurements based on the O 2 -A absorption band with field-acquired and simulated data. It was demonstrated that the uncorrected oxygen transmittance between target and sensor distance of 10 m can lead to SIF relative errors ranging from 66% to higher than 100% when using a Spectral Fitting (SF) technique …
Chlamyphilone, a Novel Pochonia chlamydosporia Metabolite with Insecticidal Activity
2019
Metabolites from a collection of selected fungal isolates have been screened for insecticidal activity against the aphid Acyrthosiphon pisum. Crude organic extracts of culture filtrates from six fungal isolates (Paecilomyces lilacinus, Pochonia chlamydosporia, Penicillium griseofulvum, Beauveria bassiana, Metarhizium anisopliae and Talaromyces pinophilus) caused mortality of aphids within 72 h after treatment. In this work, bioassay-guided fractionation has been used to characterize the main bioactive metabolites accumulated in fungal extracts. Leucinostatins A, B and D represent the bioactive compounds produced by P. lilacinus. From P. griseofulvum and B. bassiana extracts, griseofulvin an…
A new ursane-type triterpene oxoglucopyranoside from Crossopteryx febrifuga.
2019
Abstract A new saponin, 3-O-β-d-3-oxo-glucopyranosyl-ursa-12,20(30)-diene-27,28-dioic acid (1), was isolated from the methanol extract of stem bark of Crossopteryx febrifuga together with the known 3β-d-glucopyranosyl-ursa-12,20(30)-diene-27,28-dioic acid (2), shanzhiside methyl ester (3), shanzhiside (4), β-sitosterol (5), β-sitosterol-3-O-β-d-glucopyranoside (6), ursa-12,20(30)-diene-27,28-dioic acid (7), hederagenin (8), and oleanolic acid (9). The structures were established by comprehensive interpretation of their spectral data 1D- (1H and 13C), 2D-NMR (1H-1H COSY, HMQC, HMBC), spectroscopic, and electrospray ionisation time-of-flight mass spectrometry analysis. The isolated compounds …
New Acyclic Cytotoxic Jasplakinolide Derivative from the Marine Sponge Jaspis splendens
2019
A new acylic jasplakinolide congener (2), another acyclic derivative requiring revision (4), together with two jasplakinolide derivatives including the parent compound jasplakinolide (1) were isolated from the Indonesian marine sponge Jaspis splendens. The chemical structures of the new and known compounds were unambiguously elucidated based on HRESIMS and exhaustive 1D and 2D NMR spectral analysis as well as a comparison of their NMR data with those of jasplakinolide (1). The isolated jasplakinolides inhibited the growth of mouse lymphoma (L5178Y) cells in vitro with IC50 values in the low micromolar to nanomolar range.