scholarly journals Excess copper induces structural changes in cultured photosynthetic soybean cells

2006 ◽  
Vol 33 (11) ◽  
pp. 1001 ◽  
Author(s):  
María Bernal ◽  
Pilar Sánchez-Testillano ◽  
María del Carmen Risueño ◽  
Inmaculada Yruela
Keyword(s):  
Cell Wall ◽  
Structural Changes ◽  
Copper Tolerance ◽  
Copper Stress ◽  
Induced Response ◽  
Cytoplasmic Vacuole ◽  
Cell Nuclei ◽  
Short Term ◽  
Excess Copper

Soybean [Glycine max (L.) Merr.] cell suspensions have the capacity to develop tolerance to excess copper, constituting a convenient system for studies on the mechanisms of copper tolerance. The functional cell organisation changes observed in these cell cultures after both short-term (stressed cells) and long-term (acclimated cells) exposure to 10 μm CuSO4 are reported from structural, cytochemical and microanalytical approaches. Cells grown in the presence of 10 μm CuSO4 shared some structural features with untreated cells, such as: (i) a large cytoplasmic vacuole, (ii) chloroplasts along the thin layer of cytoplasm, (iii) nucleus in a peripheral location exhibiting circular-shaped nucleolus and a decondensed chromatin pattern, and (iv) presence of Cajal bodies in the cell nuclei. In addition, cells exposed to 10 μm CuSO4 exhibited important differences compared with untreated cells: (i) chloroplasts displayed rounded shape and smaller size with denser-structured internal membranes, especially in copper-acclimated cells; (ii) no starch granules were found within chloroplasts; (iii) the cytoplasmic vacuole was larger, especially after long-term copper exposure; (iv) the levels of citrate and malate increased. Extracellular dark-coloured deposits with high copper content attached at the outer surface of the cell wall were observed only in cells exposed to a short-term copper stress. Structural cell modifications, mainly affecting chloroplasts, accompanied the short-term copper-induced response and were maintained as stable characters during the period of adaptation to excess copper. Vacuolar changes accompanied the long-term copper response. The results indicate that the first response of soybean cells to excess copper prevents its entry into the cell by immobilising it in the cell wall, and after an adaptive period, acclimation to excess copper may be mainly due to vacuolar sequestration.

scholarly journals Perception and risk of Covid-19 and climate change: investigating analogies in a common framework

2020 ◽  
Vol 3 ◽  
Author(s):  
Antonello Pasini ◽  
Fulvio Mazzocchi
Keyword(s):  
Climate Change ◽  
Structural Changes ◽  
Short Term ◽  
Common Features ◽  
Risk Equation ◽  
Related Risk ◽  
Policy Level ◽  
Common Framework

This paper investigates analogies in the dynamics of Covid-19 pandemic and climate change. A comparison of their common features (such as nonlinearity and inertia) and differences helps us to achieve a correct scientific perception of both situations, increasing the chances of actions for their solutions. Besides, applying to both the risk equation provides different angles to analyse them, something that may result useful especially at the policy level. It shows that not only short-term interventions are needed, but also long-term strategies involving some structural changes. More specifically, it also shows that, even if climate change is probably more critical and long-lasting than the Covid-19 crisis, we still have, at least currently, more options for reducing its related risk.

Fracture Mechanics when Studying the Long-Term Strength of Concrete

2019 ◽  
Vol 945 ◽  
pp. 957-962
Author(s):  
I.L. Shubin ◽  
V.V. Dorkin ◽  
P.S. Sultygova
Keyword(s):  
Fracture Mechanics ◽  
Structural Changes ◽  
Structural Integrity ◽  
Term Strength ◽  
Short Term ◽  
Heterogeneous Structures ◽  
Temperature Action ◽  
Heating Up ◽  
Experimental And Theoretical Studies

The results of experimental and theoretical studies of the process of destruction of concrete by the methods of fracture mechanics are considered. Results of studies of long-term strength, durability and deformability of concrete subjected to a preliminary short-term temperature action up to 300° C and 400° C under load and without load are presented. It is shown that after short-term heating up to 300о С the long-term strength of concrete decreases insignificantly. It is established that heating up to 400° C can be considered the boundary of the structural integrity of concrete. The conditions for using the results of these studies in determining the values of a function that characterizes the change in the long-term strength of a material in the mechanics of heterogeneous structures are formulated. The function of the material destruction measure is introduced to describe the nature of the structural changes in the material at a given constant continuous load, and its change for different levels of a continuous load is considered.

scholarly journals Physiological framework for adaptation of stomata to CO 2 from glacial to future concentrations

2012 ◽  
Vol 367 (1588) ◽  
pp. 537-546 ◽  
Author(s):  
Peter J. Franks ◽  
Ilia J. Leitch ◽  
Elizabeth M. Ruszala ◽  
Alistair M. Hetherington ◽  
David J. Beerling
Keyword(s):  
Leaf Surface ◽  
Unit Area ◽  
Leaf Gas Exchange ◽  
Feedback Regulation ◽  
Cell Nuclei ◽  
Short Term ◽  
Dna Amount ◽  
Taxonomic Range ◽  
Operational Range

In response to short-term fluctuations in atmospheric CO 2 concentration, c a , plants adjust leaf diffusive conductance to CO 2 , g c , via feedback regulation of stomatal aperture as part of a mechanism for optimizing CO 2 uptake with respect to water loss. The operational range of this elaborate control mechanism is determined by the maximum diffusive conductance to CO 2 , g c(max) , which is set by the size ( S ) and density (number per unit area, D ) of stomata on the leaf surface. Here, we show that, in response to long-term exposure to elevated or subambient c a , plants alter g c(max) in the direction of the short-term feedback response of g c to c a via adjustment of S and D . This adaptive feedback response to c a , consistent with long-term optimization of leaf gas exchange, was observed in four species spanning a diverse taxonomic range (the lycophyte Selaginella uncinata , the fern Osmunda regalis and the angiosperms Commelina communis and Vicia faba ). Furthermore, using direct observation as well as flow cytometry, we observed correlated increases in S , guard cell nucleus size and average apparent 1C DNA amount in epidermal cell nuclei with increasing c a , suggesting that stomatal and leaf adaptation to c a is linked to genome scaling.

Statistical Blight

1982 ◽  
Vol 47 (4) ◽  
pp. 836-851 ◽  
Author(s):  
Sheldon Scheps
Keyword(s):  
Peer Review ◽  
Structural Changes ◽  
Peer Review System ◽  
Review System ◽  
Short Term ◽  
American Antiquity ◽  
Academic Degree ◽  
Certification Examinations

A short-term remedy is proposed in the hope of curtailing the proliferation of statistical and inferential error rife within the published archaeological literature. First, a study by Isbell and Schreiber, one that violates rudimentary quantitative and qualitative analytical precepts, yet nevertheless was published in American Antiquity, is discussed in depth in order to exemplify the extent to which matters have deteriorated within the discipline. Then, this analysis, in conjunction with the various compendia of statistical abuse compiled by numerous professionals within the field, is invoked as support for an argument advocating structural changes in the peer review system. Perhaps such solutions could be implemented until previously proposed long-term solutions, such as David Thomas"s call for compulsory courses and certification examinations to satisfy academic degree requirements, are finally instituted.

scholarly journals The evolving relationship between airline profitability and passenger satisfaction

2013 ◽  
Vol 24 (1) ◽  
pp. 7-21
Author(s):  
Kent N Gourdin
Keyword(s):  
Airline Industry ◽  
Structural Changes ◽  
Business Models ◽  
Quality Model ◽  
Short Term ◽  
The Past ◽  
Management Actions ◽  
Passenger Satisfaction ◽  
The U.S

This paper examines the ongoing evolution of the U.S. airline industry under deregulation. After losing money for most of the past 35 years, carriers have made structural changes to their business models that have proven to be, at least in the short term, very profitable. After delineating these management actions, the paper examines their impact on passengers. The author utilizes the Service Quality Model to analyze the long-term implications of this new operating paradigm for passenger satisfaction. Based on this analysis the paper goes on to suggest several actions management could take to improve satisfaction. Finally, conclusions are offered and areas for additional research suggested.

scholarly journals Global Value Chain Resilience: Understanding the Impact of Managerial Governance Adaptations

2022 ◽  
pp. 000812562110666
Author(s):  
Liena Kano ◽  
Rajneesh Narula ◽  
Irina Surdu
Keyword(s):  
Value Chain ◽  
Structural Changes ◽  
Lessons Learned ◽  
Value Chains ◽  
Global Value Chain ◽  
Short Term ◽  
Initial Shock ◽  
Lead Firm ◽  
The Impact

While COVID-19 has caused significant short-term disruptions in global value chains (GVCs), in the longer run, the pandemic will not be the primary catalyst in GVC evolution. As GVCs recover from the initial shock, managers will make GVC restructuring decisions guided by long-term strategic considerations. This article describes barriers that lead firm managers may encounter when rethinking location/control decisions for value chain activities and suggests that, in addition to structural changes, managerial governance adaptations are instrumental in enhancing GVCs’ long-term resilience. Lessons learned from responding to the pandemic can help managers enhance GVC efficiency in the increasingly uncertain global environment.

scholarly journals Lysozyme and Penicillin Inhibit the Growth of Anaerobic Ammonium-Oxidizing Planctomycetes

2013 ◽  
Vol 79 (24) ◽  
pp. 7763-7769 ◽  
Author(s):  
Ziye Hu ◽  
Theo van Alen ◽  
Mike S. M. Jetten ◽  
Boran Kartal
Keyword(s):  
Cell Wall ◽  
Continuous Cultivation ◽  
Penicillin G ◽  
Anammox Bacteria ◽  
Short Term ◽  
Content Type ◽  
Genome Data ◽  
Wall Structures ◽  
Anammox Activity

ABSTRACTAnaerobic ammonium-oxidizing (anammox) planctomycetes oxidize ammonium in the absence of molecular oxygen with nitrite as the electron acceptor. Although planctomycetes are generally assumed to lack peptidoglycan in their cell walls, recent genome data imply that the anammox bacteria have the genes necessary to synthesize peptidoglycan-like cell wall structures. In this study, we investigated the effects of two antibacterial agents that target the integrity and synthesis of peptidoglycan (lysozyme and penicillin G) on the anammox bacteriumKuenenia stuttgartiensis. The effects of these compounds were determined in both short-term batch incubations and long-term (continuous-cultivation) growth experiments in membrane bioreactors. Lysozyme at 1 g/liter (20 mM EDTA) lysed anammox cells in less than 60 min, whereas penicillin G did not have any observable short-term effects on anammox activity. Penicillin G (0.5, 1, and 5 g/liter) reversibly inhibited the growth of anammox bacteria in continuous-culture experiments. Furthermore, transcriptome analyses of the penicillin G-treated reactor and the control reactor revealed that penicillin G treatment resulted in a 10-fold decrease in the ribosome levels of the cells. One of the cell division proteins (Kustd1438) was downregulated 25-fold. Our results suggested that anammox bacteria contain peptidoglycan-like components in their cell wall that can be targeted by lysozyme and penicillin G-sensitive proteins were involved in their synthesis. Finally, we showed that a continuous membrane reactor system with free-living planktonic cells was a very powerful tool to study the physiology of slow-growing microorganisms under physiological conditions.

Cell wall composition and thickness affect mesophyll conductance to CO2 diffusion in Helianthus annuus under water deprivation

2020 ◽  
Vol 71 (22) ◽  
pp. 7198-7209
Author(s):  
Margalida Roig-Oliver ◽  
Panagiota Bresta ◽  
Miquel Nadal ◽  
Georgios Liakopoulos ◽  
Dimosthenis Nikolopoulos ◽  
...  
Keyword(s):  
Cell Wall ◽  
Water Deficit ◽  
Water Deprivation ◽  
Cell Wall Composition ◽  
Water Deficit Stress ◽  
Short Term ◽  
Co2 Diffusion ◽  
Short And Long Term ◽  
Bound Phenolics

Abstract Water deprivation affects photosynthesis, leaf anatomy, and cell wall composition. Although the former effects have been widely studied, little is known regarding those changes in cell wall major (cellulose, hemicelluloses, pectin, and lignin) and minor (cell wall-bound phenolics) compounds in plants acclimated to short- and long-term water deprivation and during recovery. In particular, how these cell wall changes impact anatomy and/or photosynthesis, specifically mesophyll conductance to CO2 diffusion (gm), has been scarcely studied. To induce changes in photosynthesis, cell wall composition and anatomy, Helianthus annuus plants were studied under five conditions: (i) control (i.e. without stress) (CL); (ii) long-term water deficit stress (LT); (iii) long-term water deficit stress with recovery (LT-Rec); (iv) short-term water deficit stress (ST); and (v) short-term water deficit stress with recovery (ST-Rec), resulting in a wide photosynthetic range (from 3.80 ± 1.05 μmol CO2 m−2 s−1 to 24.53 ± 0.42 μmol CO2 m−2 s−1). Short- and long-term water deprivation and recovery induced distinctive responses of the examined traits, evidencing a cell wall dynamic turnover during plants acclimation to each condition. In particular, we demonstrated for the first time how gm correlated negatively with lignin and cell wall-bound phenolics and how the (cellulose+hemicelloses)/pectin ratio was linked to cell wall thickness (Tcw) variations.

Structural Changes of Cell Wall and Lignifying Enzymes Modulations in Bean Roots in Response to Copper Stress

2009 ◽  
Vol 136 (2) ◽  
pp. 232-240 ◽  
Author(s):  
Houda Bouazizi ◽  
Hager Jouili ◽  
Anja Geitmann ◽  
Ezzeddine El Ferjani
Keyword(s):  
Cell Wall ◽  
Structural Changes ◽  
Copper Stress

scholarly journals EL SISTEMA DE FRANJA DE PRECIOS PARA LOS PRODUCTOS AGRÍCOLAS EN EL PACTO ANDINO: DEFINICION DE CAMBIO ESTRUCTURAL

1995 ◽  
pp. 9-26
Author(s):  
Manuel Del Valle ◽  
Keyword(s):  
Structural Change ◽  
Structural Changes ◽  
Band System ◽  
Short Term ◽  
Monte Carlo Test ◽  
International Prices ◽  
El Sistema ◽  
Andean Pact ◽  
Statistical Criteria

It analyzes the structural change in the context of the price band in the Andean Pact in order to advance proposals for the reform of Decision 37.1 so that it can consider the systematic and sustained changes in the international product market. The focus of the work is statistical, since the system is updated using moving averages and statistical criteria. Thirteen time series used in the price band system are analyzed and univariate models are proposed for each one of them. Furthermore, a rule is proposed to define the structural change, and the univariate models obtained are used to prove said rule using Monte Carlo test for the thirteen products. It is concluded that the price band system can be useful to face short-term fluctuations in international prices, as well as long-term adjustments, but it is not prepared to solve problems generated by structural changes, so it can be modified to consider this issue, but the basic principle of the system should be maintained.

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