The mechanism of regulation of photosystem I cross-section in the pennate diatom Phaeodactylum tricornutum

2020 ◽  
Author(s):  
Vasco Giovagnetti ◽  
Alexander V Ruban
Keyword(s):  
Phaeodactylum Tricornutum ◽  
Wavelength Region ◽  
Culture Conditions ◽  
Protein Synthesis Inhibitor ◽  
Synthesis Inhibitor ◽  
Pennate Diatom ◽  
Intermittent Light ◽  
Long Wavelength ◽  
Wavelength Emission ◽  
Photosynthetic Complexes

Abstract Photosystems possess distinct fluorescence emissions at low (77K) temperature. PSI emits in the long-wavelength region at ~710–740 nm. In diatoms, a successful clade of marine primary producers, the contribution of PSI-associated emission (710–717 nm) has been shown to be relatively small. However, in the pennate diatom Phaeodactylum tricornutum, the source of the long-wavelength emission at ~710 nm (F710) remains controversial. Here, we addressed the origin and modulation of F710 fluorescence in this alga grown under continuous and intermittent light. The latter condition led to a strong enhancement in F710. Biochemical and spectral properties of the photosynthetic complexes isolated from thylakoid membranes were investigated for both culture conditions. F710 emission appeared to be associated with PSI regardless of light acclimation. To further assess whether PSII could also contribute to this emission, we decreased the concentration of PSII reaction centres and core antenna by growing cells with lincomycin, a chloroplast protein synthesis inhibitor. The treatment did not diminish F710 fluorescence. Our data suggest that F710 emission originates from PSI under the conditions tested and is enhanced in intermittent light-grown cells due to increased energy flow from the FCP antenna to PSI.

A facile and universal strategy for preparation of long wavelength emission carbon dots

2017 ◽  
Vol 46 (48) ◽  
pp. 16905-16910 ◽  
Author(s):  
Yanan Liu ◽  
Tianxiang Zhang ◽  
Rong Wang ◽  
Haining Cui ◽  
Hongwei Song
Keyword(s):  
Carbon Dots ◽  
Wavelength Region ◽  
Emission Wavelength ◽  
Long Wavelength ◽  
New Type ◽  
Wavelength Emission

Carbon dots (CDs) have emerged as a promising new type of fluorescent nanomaterial, although one of their main problems is the tuning of the emission wavelength toward the long wavelength region.

Modulation of Arachidonic Acid Metabolism in Human Endothelial Cells by Glucocorticoids

1986 ◽  
Vol 55 (03) ◽  
pp. 369-374 ◽  
Author(s):  
Raffaele De Caterina ◽  
Babette B Weksler
Keyword(s):  
Endothelial Cells ◽  
Vascular Endothelial Cells ◽  
Umbilical Vein ◽  
Arachidonic Acid Metabolism ◽  
Protein Synthesis Inhibitor ◽  
Synthesis Inhibitor ◽  
Prolonged Incubation ◽  
Dependent Inhibition ◽  
Human Thrombin ◽  
Umbilical Vein Endothelial Cells

SummaryTo learn whether glucocorticoids inhibit prostaglandin (PG) production in vascular endothelial cells, we investigated the effects of glucocorticoids on PG synthesis by cultured human umbilical vein endothelial cells (EC). Pretreatment of EC with dexamethasone (DX, 10-9 to 5 x 10-5 M) caused a dose-dependent inhibition of PGI2 production when PG synthesis from endogenous arachidonate was stimulated by human thrombin (0.25-2 U/ml) or ionophore A 23187 (1-5 μM). The inhibition was detectable at 10-7 M DX and maximal at 10-5 M (4.0 ± 0.7 vs. control: 7.7 ± 1.9 ng/ml, mean ± S.D., P <0.01). The production of PGE2 and the release of radiolabelled arachidonate (AA) from prelabelled cells were similarly inhibited. Prolonged incubation of EC with glucocorticoids was required to inhibit PG production or arachidonate release: ranging from 8% inhibition at 5 h to 44% at 38 h. In contrast, prostaglandin formation from exogenous AA was not altered by DX treatment. When thrombin or ionophore-stimulated EC were restimulated with exogenous AA (25 μM), DX-treated cells released more PGI2 than control cells (5.7 ± 0.5 vs. 4.1 ± 0.6 ng/ml, P <0.01). Both the decrease in PGI2 production after thrombin/ionophore and the increase after re-stimulation with AA were blunted in the presence of the protein synthesis inhibitor cycloheximide (0.1-0.2 μg/ml). Thus, incubation of EC with glucocorticoids inhibits PG production at the step of phospholipase activation. The time requirement for these steroid effects and their blunting by cycloheximide are consistent with the induction of regulatory proteins, possibly lipocortins, in endothelial cells.

Influence of solvent polarity on the dual fluorescence of p-N,N-dimethylaminobenzonitrile: An AM1 theoretical study

1990 ◽  
Vol 55 (8) ◽  
pp. 1891-1895 ◽  
Author(s):  
Peter Ertl
Keyword(s):  
Excited State ◽  
Theoretical Study ◽  
Solvent Polarity ◽  
Semiempirical Method ◽  
Dual Fluorescence ◽  
Long Wavelength ◽  
Polar Media ◽  
Wavelength Emission ◽  
Ground State Geometry ◽  
Influence Of Solvent

Twisting of the NMe2 group in p-N,N-dimethylaminobenzonitrile (DMABN) was investigated using AM1 semiempirical method with configuration interaction. Effect of polar media was considered by placing + and - charge centers ("sparkles") at appropriate places opposite the molecule. Optimized ground state geometry of DMABN is slightly twisted with the lowest vertical excited state of 1B character. As the polarity of media increases and/or the - NMe2 group twists, the symmetric 1A excited state having considerable charge separation becomes energetically favorable. Anomalous long-wavelength emission of DMABN comes from this state.

scholarly journals Effect of emetine, a protein synthesis inhibitor, on larval tail resorption in the ascidian Halocynthia roretzi

2006 ◽  
Vol 23 (2) ◽  
pp. 43-46
Author(s):  
Kiyotaka Matsumura ◽  
Manami Nagano ◽  
Sachiko Tsukamoto ◽  
Haruko Kato ◽  
Nobuhiro Fusetani
Keyword(s):  
Protein Synthesis ◽  
Protein Synthesis Inhibitor ◽  
Synthesis Inhibitor ◽  
Halocynthia Roretzi

Combining the deep Earth and lithospheric gravity field to study the density structure of the upper mantle

2021 ◽  
Author(s):  
Bart Root ◽  
Javier Fullea ◽  
Jörg Ebbing ◽  
Zdenek Martinec
Keyword(s):  
Gravity Field ◽  
Shear Wave ◽  
Wave Velocity ◽  
Shear Wave Velocity ◽  
Field Data ◽  
Wavelength Region ◽  
Density Structure ◽  
Long Wavelength ◽  
Global Gravity ◽  
Deep Earth

&lt;p&gt;Global gravity field data obtained by dedicated satellite missions is used to study the density distribution of the lithosphere. Different multi-data joint inversions are using this dataset together with other geophysical data to determine the physical characteristics of the lithosphere. The gravitational signal from the deep Earth is usually removed by high-pass filtering of the model and data, or by appropriately selecting insensitive gravity components in the inversion. However, this will remove any long-wavelength signal inherent to lithosphere. A clear choice on the best-suited approach to remove the sub-lithospheric gravity signal is missing.&amp;#160;&lt;/p&gt;&lt;p&gt;Another alternative is to forward model the gravitational signal of these deep situated mass anomalies and subtract it from the observed data, before the inversion. Global tomography provides shear-wave velocity distribution of the mantle, which can be transformed into density anomalies. There are difficulties in constructing a density model from this data. Tomography relies on regularisation which smoothens the image of the mantle anomalies. Also, the shear-wave anomalies need to be converted to density anomalies, with uncertain conversion factors related to temperature and composition. Understanding the sensitivity of these effects could help determining the interaction of the deep Earth and the lithosphere.&lt;/p&gt;&lt;p&gt;In our study the density anomalies of the mantle, as well as the effect of CMB undulations, are forward modelled into their gravitational potential field, such that they can be subtracted from gravity observations. The reduction in magnitude of the density anomalies due to the regularisation of the global tomography models is taken into account. The long-wavelength region of the density estimates is less affected by the regularisation and can be used to fix the mean conversion factor to transform shear wave velocity to density. We present different modelling approaches to add the remaining dynamic topography effect in lithosphere models. This results in new solutions of the density structure of the lithosphere that both explain seismic observations and gravimetric measurements. The introduction of these dynamic forces is a step forward in understanding how to properly use global gravity field data in joint inversions of lithosphere models.&lt;/p&gt;

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