The Influence of the Proton Gradient on the Activation of Ferredoxin-NADP+-oxidoreductase by Light

1988 ◽  
Vol 43 (3-4) ◽  
pp. 207-212 ◽  
Author(s):  
Roland Pschorn ◽  
Wolfgang Rühle ◽  
Aloysius Wild
Keyword(s):  
Active Form ◽  
Cytochrome F ◽  
Proton Gradient ◽  
Activation Process ◽  
Dark Light ◽  
Induction Kinetics ◽  
Fluorescence Quench ◽  
Steady State Rate ◽  
State Rate

Ferredoxin-NADP+-oxidoreductase (FNR, EC 1.18.1.2) has been shown to be activated by light within a few seconds during dark-light transitions and inactivated in the dark. In previous papers this could be pointed out by the correlation of cytochrome f induction kinetics to the rate of NADP-photoreduction and the variable fluorescence. The present study deals with the role of the proton gradient during the activation process. The transition from an inactive to an active form is followed continuously in an in situ system. The steady-state rate of NADP-photoreduction is affected only by ionophores which inhibit a formation of the proton gradient, but not by inhibitors of the electric field. It correlates to the 9-aminoacridine fluorescence quench and the light scattering signals at 535 nm. The perception of the pH-gradient through the enzyme is still a matter of discussion.

scholarly journals The role of metarhodopsin in the generation of spontaneous quantum bumps in ultraviolet receptors of Limulus median eye. Evidence for reverse reactions into an active state.

1985 ◽  
Vol 85 (2) ◽  
pp. 171-187 ◽  
Author(s):  
J Lisman
Keyword(s):  
Steady State ◽  
Molecular Switch ◽  
Active State ◽  
Significant Source ◽  
Steady State Rate ◽  
State Rate

The origin of spontaneous quantum bumps has been examined in the ultraviolet photoreceptors of Limulus median eye. These cells have a rhodopsin with a lambda max at 360 nm and a stable photoproduct, metarhodopsin, with a lambda max at 470 nm. The steady state rate of spontaneous quantum bumps was found to be higher when the metarhodopsin concentration was high than when the rhodopsin concentration was high. This result implicates metarhodopsin in the generation of spontaneous quantum bumps. Furthermore, this result is consistent with the idea that the reaction which inactivates metarhodopsin (terminates the ability of metarhodopsin to initiate the reactions leading to a quantum bump) is reversible and that such reversions can be a significant source of spontaneous quantum bumps. Given that the rate of spontaneous quantum bumps is approximately 1/s under conditions where the number of inactive metarhodopsin molecules is approximately 10(9), it follows that the molecular switch that inactivates metarhodopsin reverses with a probability of less than 10(-9). A model is presented of how a molecular switch with this reliability might be constructed.

scholarly journals Amplification characteristics in active tapered segmented cladding fiber with large mode area

2021 ◽  
Vol 9 ◽  
Author(s):  
Caijian Xie ◽  
Tigang Ning ◽  
Jingjing Zheng ◽  
Li Pei ◽  
Jianshuai Wang ◽  
...  
Keyword(s):  
High Power ◽  
Heat Load ◽  
Nonlinear Effects ◽  
Single Mode ◽  
Large Mode Area ◽  
High Loss ◽  
Effective Mode Area ◽  
Steady State Rate ◽  
State Rate ◽  
Mode Area

Abstract A kind of tapered segmented cladding fiber (T-SCF) with large mode area (LMA) is proposed, and the mode and amplification characteristics of T-SCFs with concave, linear, and convex tapered structures are investigated based on finite-element method (FEM) and few-mode steady-state rate equation. Simulation results indicate that the concave tapered structure can introduce high loss for high-order modes (HOMs) that is advantageous to achieve single-mode operation, whereas the convex tapered structure provides large effective mode area that can help to mitigate nonlinear effects. Meanwhile, the small-to-large amplification scheme shows further advantages on stripping off HOMs, and the large-to-small amplification scheme decreases the heat load density induced by the high-power pump. Moreover, single-mode propagation performance, effective mode area, and heat load density of the T-SCF are superior to those of tapered step index fiber (T-SIF). These theoretical model and numerical results can provide instructive suggestions for designing high-power fiber lasers and amplifiers.

scholarly journals Rab3D regulates amylase levels, not agonist-induced amylase release, in AR42J cells

2012 ◽  
Vol 17 (2) ◽  
Author(s):  
Saima Limi ◽  
George Ojakian ◽  
Robert Raffaniello
Keyword(s):  
Secretory Granules ◽  
Active Form ◽  
Subcellular Fractionation ◽  
Amylase Release ◽  
Ar42j Cells ◽  
Granule Density ◽  
Granule Morphology ◽  
Pancreatic Exocrine

AbstractRab3D is a low molecular weight GTP-binding protein that associates with secretory granules in exocrine cells. AR42J cells are derived from rat pancreatic exocrine tumor cells and develop an acinar cell-like phenotype when treated with dexamethasone (Dex). In the present study, we examined the role of Rab3D in Dex-treated AR42J cells. Rab3D expression and localization were analyzed by subcellular fractionation and immunoblotting. The role of Rab3D was examined by overexpressing myc-labeled wild-type-Rab3D and a constitutively active form of Rab3D (Rab3D-Q81L) in AR42J cells. We found that Rab3D is predominantly membrane-associated in AR42J cells and co-localizes with zymogen granules (ZG). Following CCK-8-induced exocytosis, amylase-positive ZGs appeared to move towards the periphery of the cell and co-localization between Rab3D and amylase was less complete when compared to basal conditions. Overexpression of WT, but not mutant Rab3D, resulted in an increase in cellular amylase levels. Overexpression of mutant and WT Rab3D did not affect granule morphology, CCK-8-induced secretion, long-term (48 hr) basal amylase release or granule density. We conclude that Rab3D is not involved in agonist-induced exocytosis in AR42J cells. Instead, Rab3D may regulate amylase content in these cells.

Corticosterone secretion in rats as a function of ACTH input and adrenal blood flow

1965 ◽  
Vol 209 (4) ◽  
pp. 811-814 ◽  
Author(s):  
John C. Porter ◽  
M. S. Klaiber
Keyword(s):  
Blood Flow ◽  
Steady State ◽  
Steady Increase ◽  
Constant Input ◽  
Corticosterone Secretion ◽  
Steady State Rate ◽  
State Rate

The rate of secretion of corticosterone from the left adrenal of rats receiving a constant input of ACTH was determined for different flows of blood through the adrenal during the 2- to 3-hr interval following hypophysectomy. Two hours after hypophysectomy the secretion of corticosterone was low in all groups regardless of flow. An input of 0.26 mU ACTH/min caused a steady increase in secretion for 30–40 min before a steady-state rate was attained. The average steady-state rate of secretion was 1.1, 2.4, 3.5, 6.2, 7.2, 6.2, and 6.2 µg/5 min for flows of 0.005, 0.012, 0.023, 0.034, 0.039, 0.051, and 0.058 ml/min, respectively. Under the conditions of these experiments where the input of ACTH was 0.26 mU/min the secretion of corticosterone increased significantly with time of input of ACTH and with flow of blood through the adrenal.

AN "ACTIVATION" PROCESS FOR ENTREPRENEURIAL ENGINEERING EDUCATION: THE MODEL AND APPLICATION

2011 ◽  
Vol 19 (02) ◽  
pp. 147-168 ◽  
Author(s):  
GIANLUCA ELIA ◽  
A. MARGHERITA ◽  
G. SECUNDO ◽  
K. MOUSTAGHFIR
Keyword(s):  
Engineering Education ◽  
Research Training ◽  
Economic Value ◽  
Activation Process ◽  
Technology Entrepreneurship ◽  
Hands On ◽  
Research Training Program ◽  
Develop Technology ◽  
Market Solutions

The pervasiveness of scientific developments has raised the role of entrepreneurship as a driver of socio-economic value. Higher education institutions are thus asked to create entrepreneurial mindset and competencies with the purpose to make students people able to proactively identify opportunities and transform them in market solutions. In particular, engineering education programs can be of relevance to develop technology entrepreneurship competencies through hands-on and experiential approaches. In such vein, this paper proposes a model of entrepreneurship education as an "activation" process which uses four critical levers with the purpose to infuse the essence of entrepreneurship in tomorrow's engineering professionals. The application of the model is exemplified through the analysis of a research training program grounded in the aerospace domain. The key features of the initiative are discussed in the perspective of exploring new models of entrepreneurial engineering education.

scholarly journals EFFECT OF EXTRACHROMOSOMAL ELEMENTS OF HEREDITY ON TOXIC PROPERTIES OF YERSINIA PESTIS

2017 ◽  
pp. 28-33 ◽  
Author(s):  
G. V. Demidova ◽  
E. P. Sokolova ◽  
V. P. Zyuzina ◽  
V. A. Rykova ◽  
I. V. Morozova ◽  
...  
Keyword(s):  
Yersinia Pestis ◽  
Active Form ◽  
Infectious Agent ◽  
Toxic Shock ◽  
Toxic Activity ◽  
Virulent Strains ◽  
Extrachromosomal Elements ◽  
Live Bacteria ◽  
First Time

Aim. Elucidation of the role of extrachromosomal elements of heredity in manifestations of toxic properties of Yersinia pestis. Materials and methods. The study was carried out in vaccine strain Y. pestis EV76 (pMTl, pCDl, pPCPl) and non-plasmid variants of vaccine EV76 (pMTl\ pCDl', pPCPl') and virulent 231 (рМТГ, pCDl’, pPCPl') strains of Y. pestis. Presence of functionally active form of lipopolysaccharide (LPS) in the incubation medium of the bacteria was evaluated via toxicity of supernatant of Y. pestis for intact animals (infection-toxic shock) and mice sensitized by D-GalN. Results. 37°C cultures of Y. pestis EV76 containing a full amount of plasmids were established to release LPS into the environment. Non-plasmid variants of both vaccine and virulent strains of Y. pestis pMTl', pCD Г, рРСР 1 do not have this ability. Separation of LPS from cell wall was detected in live bacteria of plague infectious agent. This process is assumed to be coupled with translocation of proteins coded by pMTl, pCDl, pPCPl plasmids from the cell into the environment. Conclusion. Functional interconnection between extrachromosomal elements of heredity and toxic activity of Y. pestis LPS is established for the first time.

scholarly journals The Natural Rate of Interest and the Optimal Rate of Interest in the Steady State

2021 ◽  
pp. 17-41
Author(s):  
Carl Christian von Weizsäcker ◽  
Hagen M. Krämer
Keyword(s):  
Steady State ◽  
Public Debt ◽  
Fundamental Equation ◽  
Optimal Rate ◽  
Natural Rate ◽  
Real Rate ◽  
Capital Theory ◽  
Steady State Rate ◽  
Natural Rate Of Interest ◽  
State Rate

AbstractThe “natural rate of interest” is the hypothetical, risk-free real rate of interest that would obtain in a closed economy, if net public debt were zero. It is considerably less than the optimal steady-state rate of interest, which is equal to the system’s growth rate. This holds for a very general “meta-model.” The fundamental equation of capital theory holds on the optimal steady-state path: T = Z − D, where T is the overall economic period of production, Z is the representative private “waiting period” of consumers and D is the public debt ratio. Prosperity is at least 30% lower at the natural rate of interest than at the optimal rate.

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