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Nowadays, it is relevant to consider changes in the structure of the fuel and energy balance of industrial regions and the availability of imported fuel and energy resources, especially in the areas that lack energy sources. The ongoing structural shifts in energy consumption systems and the growing uncertainty in energy markets encourage the development of tools for improving the sustainable development of regional energy systems. To refine the theoretical and methodological basis of the study, we defined its conceptual framework, described the difference s betwee n sustainabl e functionin g an d developmen t o f th e energy sector and determined the factors of its regional differentiation and manifestations of the energy crisis. Further, we identified the shortcomings of the existing methods for forecasting the demand for electricity. We paid special attention to quality factors of strategic planning in the region, in particular, the used statistics and documents. Based on the analysis of integrated resource planning (IRP) methodology, our experience in forecasting fuel and energy balances, assessment of sectoral indicators of energy efficiency and energy demand in the region, we proposed a model for predictive and analytical justification of regional programmes for energy development. Such a model significantly increases the information reliability of these programmes’ implementation. Considering organisational tools to support sustainable development, we developed a regional energy management scheme and a mechanism stimulating local energy companies to improve energy efficiency in the consumption sector, enhance regional competition and attract investments in the renewal of fixed assets. The study has practical significance due to recommendations and tools for adjusting regional energy policy based on the coordination of the predicted parameters for various participants in the energy supply process.

The training of digital economy specialists requires new approaches to the educational process, which should contain updated training materials and flexible teaching formats and methods. Moreover, it should create competencies for working in the conditions of uncertainty and maintain readiness to solve complex problems in the process of professional activity. Close integration of scientific and educational activities is the only possible approach to attain this goal. Thus, we suggested a mechanism for rapidly transferring the latest results of scientific research to the educational process at universities in order to organize anticipatory learning. We demonstrated the organizational principles, content and methods of this mechanism on the example of managerial training. We have substantiated and described the research area «Pre-emptive management in rapidly developing industries and sectors», as well as the key provisions of anticipatory learning and its knowledge base. Further, we have discussed the possibilities of applying the technology platforms for designing branded educational products with flexible modular structure. Thanks to such structure, the training programs function as a continuous conveyor for continuous competency building. In the paper, we present a conceptual project and an operational mechanism of a university-based scientific and educational platform. Testing on the Ural Federal University (UrFU) has proved the efficiency of the suggested methods and validity of the research results. The proposed platform can be used for establishing world-class Research and Educational Centres in the region aimed at developing global research and industrial cooperation in order to create breakthrough innovations.

Stephen D Persell, 1, 2 Kunal N Karmali, 3 Ji Young Lee, 1 Danielle Lazar, 4 Tiffany Brown, 1 Elisha M Friesema, 1, 2, 5 Michael S Wolf 1 1Division of General Internal Medicine and Geriatrics, Department of Medicine, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA; 2Center for Primary Care Innovation, Institute for Public Health and Medicine, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA; 3Division of Cardiology, Department of Medicine, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA; 4Access Community Health Network and the ACCESS Center for Discovery and Learning, Chicago, IL, USA; 5Carlson School of Management, University of Minnesota, Minneapolis, MN, USACorrespondence: Stephen D PersellDivision of General Internal Medicine and Geriatrics, Department of Medicine Feinberg School of Medicine, Northwestern University, 750 North Lake Shore Drive, 10th Floor, Chicago, IL 60611, USATel +1 312 503 6464Fax +1 312 503 2755Email spersell@nm.orgPurpose: Examine associations between health literacy and several medication self-management constructs among a population of adults with uncontrolled hypertension.Patients and Methods: Cross-sectional study of health center patients from the Chicago area with uncontrolled hypertension enrolled between April 2012 and February 2015. Medication self-management constructs—applied to hypertension medications, chronic condition medications and all medications—included: 1) medication reconciliation, 2) knowledge of drug indications, 3) understanding instructions and dosing, and 4) self-reported adherence over 4 days (no missed doses). We determined associations between health literacy and self-management outcomes using multivariable generalized linear regression.Results: There were 1460 patients who completed screening interviews; 62.9% enrolled and had complete baseline data collected, and were included in the analysis. Of 919 participants, 47.4% had likely limited (low), 33.2% possibly limited, and 19.4% likely adequate health literacy. Compared to participants with likely adequate health literacy, participants with low health literacy were less likely to have chronic medications reconciled (18.0% versus 29.6%, p=0.007), know indications for chronic medications (64.1% versus 83.1%, p< 0.001), and demonstrate understanding of instructions and dosing (68.1% versus 82.9%, p=0.001). Self-reported adherence to hypertension medications was higher among the low health literacy group (65.6% versus 56.0%, p=0.010). In multivariable models, health literacy was strongly associated with knowledge of drug indications, and understanding of instructions and dosing.Conclusion: Low health literacy was associated with worse medication self-management in several domains. However, non-adherence was greatest in the most health literate in unadjusted analysis. Among a population of patients with uncontrolled hypertension, the drivers of poor control may vary by health literacy.Keywords: health literacy, hypertension, medication reconciliation, community health centers

The subject of the analysis of our paper is the social and cultural practice of amateur basketball played by employees of the multinational company Ernst Young in Belgrade. We observed the amateur team as a folklore group, and their participation in sports is interpreted not only as a physical activity, but as a modality of shaping attitudes, values and beliefs related to the company, important for strengthening cohesion among employees and reinforcing their motivation to perform work tasks. Basketball as a sport in which each player aligns on an individual level with the collective strategy of the team is somewhat reminiscent of the activities of Ernst Young employees, such as teamwork, personal and professional development, as well as an organizational culture oriented towards the company’s development and growth on the market. The material in this paper was collected using the technique of semi-structured interviews with members of the amateur basketball team Ernst Young, which competes in the Rekreativ League of Belgrade and is composed mainly of employees in this organization. In addition to this base of our ethnographic material, informal interviews were conducted and employee statementsobtained. Using the concept of idioculture of the American sociologist, social psychologist and folklorist Gary Alan Fine, the material related to the creation, expression and subsistence of the group’s identity (composed mostly of amateur basketball players) was analyzed and interpreted. Members of this sports community differentiate themselves from other employees in the multinational company through the mentioned group identity. The group is recognized as such by other employees in this organization, which was shown by further analysis performed in accordance with the theoretical and methodological framework of the “folklore diamond” established by Gary Alan Fine. However, Fine himself never applied this framework consistently according to all its elements of analysis. The selection of these elements is made with regard to what is being examined, hence Fine’s “folklore diamond” is used as a source from which analytical concepts are taken and combined. The cultural context, as another element, gives a more complete picture of the overall analysis. This gives us an impetus for further ethnological and anthropological research of amateur sports in Serbia, especially in the corporate work environment.

The liquidity crunch arising out of volatile market conditions is a significant concern for investors across the globe. The trading activity in the market is an important attribute determining the liquidity as well as the volatility of any stock market. Given this triangular relationship, this study analyzes the relationship between liquidity, volatility and trading activity in the Indian stock market. Employing OLS regression estimates, the study identifies a contraction in liquidity in response to greater trading activity which is found to be increasing volatility in the market. It finds that higher volatility in Indian market is associated with greater illiquidity in the market. Even after adjusting for the impact of trading activity, volatility is found to be exhibiting a statistically significant impact on liquidity.Keywords: Indian stock market, intraday liquidity, OLS regression, trading activity, volatilityJEL Classifications: C1, G11, G12DOI: https://doi.org/10.32479/ijefi.7268

Oscillations in many of photosynthetic quantities with a period of about 1 min can be routinely measured with higher plant leaves after perturbation of the steady state by sudden change in gas phase. Among all hypotheses suggested so far to explain the oscillations, an effect of ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBPCO) activation status to control the oscillations is highly probable, at least upon high temperature (HT) treatment when in vivo RuBPCO activity controlled by RuBPCO activase (RuBPCO-A) decreases. Therefore, we measured the oscillations in fluorescence signal coming from barley leaves ( Hordeum vulgare L. cv. Akcent) after their exposure for various time intervals to different HTs in darkness. We also evaluated steady state fluorescence and CO2 exchange parameters to have an insight to functions of electron transport chain within thylakoid membrane and Calvin cycle before initiation of the oscillations. The changes in period of the oscillations induced by moderate HT (up to 43 °C) best correlated with changes in non-photochemical fluorescence quenching (qN) that in turn correlated with changes in gross photosynthetic rate ( PG) and rate of RuBPCO activation (kact). Therefore, we suggest that changes in period of the oscillations caused by moderate HT are mainly controlled by RuBPCO activation status. For more severe HT (45 °C), the oscillations disappeared which was probably caused by an insufficient formation of NADPH by electron transport chain within thylakoid membrane as judged from a decrease in photochemical fluorescence quenching (qP). Suggestions made on the basis of experimental data were verified by theoretical simulations of the oscillations based on a model of Calvin cycle and by means of a control analysis of the model. [ABSTRACT FROM AUTHOR]

Vehicles’ breaking system is one of the basic elements that lead to the maintenance of technical and road safety during transport activities on public roads or other special conditions. Therefore, particular attention is paid to all maintenance work planned or occasionally carried out on such system, as a high coefficient of vehicles availability results in an increased percentage of their productivity. Of course, there is diagnosis equipment for each element, and the brake booths within MOT centres accurately indicate the values of the measured parameters, following repair, adjustment and control operations for troubleshooting. Still, there are certain cases requesting the check of breaking system either analytically or by field experiments, i.e. when vehicles are driven on rough and rugged ground, during military specific missions and activities, where their performance no longer allows specialized equipment or when such equipment does not exist. This works presents alternatives to determine the technical condition of the braking system by means of typical solutions for the general diagnosis type.

OBJECTIVE:The aim of this study was to evaluate the results of endovascular therapy on the treatment of different types of iliac occlusions. MATERIALS AND METHODS:A bi-center prospective, non-randomized study was conducted on 100 patients (mean age 59.14 ± 8.53; 64 men) who underwent endovascular treatment of iliac occlusive disease between January 2013 and November 2017. We evaluated baseline data, procedure, and follow-up results for the entire group, and according to Trans-Atlantic Inter-Society Consensus (TASC II) classification. The majority of patients (60%) were treated for severe claudication; 56 (56%) patients had TASC B occlusions, 28 patients TASC C, and 16 patients TASC D. RESULTS:The mean length of the occluded segments was 61.41 ± 35.15 mm. Procedural complications developed in 6 patients (6%). Mean ankle-brachial pressure index increased from 0.40 ± 0.12 preoperatively to 0.82 ± 0.16 postoperatively. The mean follow-up was 33.18 ± 15.03 months. After 1 and 5 years, the primary patency rates were 98% and 75.1%, and the secondary patency rate was 97% respectively. Regarding occlusion complexity there were no statistical significant differences in primary patency rates (TASC B vs. C vs. D: p = 0.19). There were no statistically significant differences in primary patency rates between patients in different clinical stages, as well as between the type of stents, and location of the occlusion. CONCLUSION:In our study, endovascular treatment for iliac artery occlusions proved to be a safe and efficient approach with excellent primary and secondary patency rates regardless of the complexity of occlusions defined by TASC II classification. This study is aligned with the notion that in well selected patients, endovascular therapy can be the treatment of choice even in complex iliac lesions if performed by experienced endovascular interventionists in high volume centers.

Innovative economic development requires principally updated approach to the process of managers training, taking into account the increase in the complexity and scale of the problems that must be addressed to managers. The purpose of the work is to improve the methodological approach to the formation of the manager’s competence in the innovative economy. The paper analyzes the existing problems of managers’ education, the new paradigm of the educational process is substantiated. The need to strengthen the learning process in a multidisciplinary approach and the technical and economic training is shown. The model of manager professionalism representing interdisciplinary complex interdependent competencies is proved. Experimental testing of methods and technologies of an interdisciplinary approach to managers’ training in the organizational form of a research and educational center (REC «INZHEK», Ural Federal University) is demonstrated. Implementation of the results obtained by the authors will mainstream managers’ training in the context of real-world problems of industries modernization.

The article deals with a promising approach to solving the problem of investment in the regional electric power industry — the application of demand-side management, the essence of which lies in proactive interaction of energy companies with customers, based on the balance of economic interests. The features of the concept and its tools are revealed, positive results of its implementation for energy market players and the region are shown, and examples of demand-side management programs are given. Institutional and mental barriers to effective implementation of demand-side management tools in power generation are analyzed. The article also proposes algorithms for implementing demand-side management programs in the region, and a mix of motivational activities that combines methods of administrative enforcement and economic stimulus for energy companies and consumers of energy and power, as well as guidelines on project funding and effectiveness evaluation.

Genetic screening on chromosomopathy has been performed on 2000 pregnant women in their first trimester of pregnancy by determining Pregnancy associated plasma protein-A and free-beta HCG biomarkers in maternal serum. After obtaining a normal fetal karyo type, the pathological values of the biomarkers have been correlated with other pregnancy disorders, and the possible causes of the positive genetic screening have been tested. 340 false positive biomarkers (17%) have been detected. The increased free-beta HCG (48.24%) had a significant influence. A significant correlation (p > 0.01) between the increased free-beta HCG and bleeding during pregnancy has been established. Complications occurred in 78.52% pregnancies with pathological biomarkers, MISSed in 13.82%, miscarriages in 10.88%, induced pregnancy terminations caused by fetal anomalies in 8.82% and births with disturbed fetal vitality in 45%. The research results have shown a significant correlation (p > 0.01) between the increased value of the free-beta HCG biomarkers and fetal hypoxia. The false positive genetic screening, caused by the increased free-beta HCG, can indicate placental dysfunction and fetal vitality disruption. .

To evaluate the changes in serum neuron specific enolase and protein S-100B, after carotid endarterectomy performed using the conventional technique with routine shunting and patch closure, or eversion technique without the use of shunt.Prospective non-randomized study included 43 patients with severe (>80%) carotid stenosis undergoing carotid endarterectomy in regional anesthesia. Patients were divided into two groups: conventional endarterectomy with routine use of shunt and Dacron patch (csCEA group) and eversion endarterectomy without the use of shunt (eCEA group). Protein S-100B and NSE concentrations were measured from peripheral blood before carotid clamping, after declamping and 24 hours after surgery.Neurologic examination and brain CT findings on the first postoperative day did not differ from preoperative controls in any patients. In csCEA group, NSE concentrations decreased after declamping (P

Autor je izvijestio o zanimljivim podrobnostima iz priložene korespondencije P. Skoka s njegovim suvremenicima koja osvjetljava zanimljivu atmosferu tadašnjega gledanja na toponomastičku problematiku i na metode toponomastičkog skupljanja građe i njezine obradbe.

Abstract Advanced renal cell carcinoma accompanied by tumor thrombus in the venous system is present in up to 10% of cases. Extension of tumor thrombus above the diaphragm or into the right atrium represents level IV disease. Level IV tumors are typically treated with sterno-laparotomy approach with or without deep hypothermic circulatory arrest and veno-venous bypass. In this case report, the surgical technique for the resection of advanced RCC were described, with the concomitant use of transesophageal echocardiography for thrombus extraction without the veno-venous or cardiopulmonary bypass.

Alternating electric current and alternating electromagnetic fields revolutionized physics and engineering and led to many technologies that shape modern life. Despite these undisputable achievements that have been reached using stimulation by harmonic oscillations over centuries, applications in biology remain rare. Photosynthesis research is uniquely suited to unleash this potential because light can be modulated as a harmonic function, here sinus. Understanding the response of photosynthetic organisms to sinusoidal light is hindered by the complexity of dynamics that such light elicits, and by the mathematical apparatus required for understanding the signals in the frequency domain which, although well-established and simple, is outside typical curricula in biology. Here, we approach these challenges by presenting a mathematical model that was designed specifically to simulate the response of photosynthetic light reactions to light which oscillates with periods that often occur in nature. The independent variables of the model are the plastoquinone pool, the photosystem I donors, lumen pH, ATP, and the chlorophyll fluorescence (ChlF) quencher that is responsible for the qE non-photochemical quenching. Dynamics of ChlF emission, rate of oxygen evolution, and non-photochemical quenching are approximated by dependent model variables. The model is used to explain the essentials of the frequency-domain approaches up to the level of presenting Bode plots of frequency-dependence of ChlF. The model simulations were found satisfactory when compared with the Bode plots of ChlF response of the green alga Chlamydomonas reinhardtii to light that was oscillating with a small amplitude and frequencies between 7.8 mHz and 64 Hz., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: L.Nedbal owns a small start-up PSI Scientific that recently published a preprint https://www.biorxiv.org/content/10.1101/2024.04.18.589113v1 reporting an instrument that performs protocols similar to those simulated by this model. Other authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Masson SAS. All rights reserved.)

Our study attempts to address the following questions: among numerous photosynthetic modules, which parameters notably influence the rapid chlorophyll fluorescence (ChlF) rise, the so-called O-J-I-P transient, in conjunction with the P515 signal, as these two records are easily obtained and widely used in photosynthesis research, and how are these parameters ranked in terms of their importance? These questions might be difficult to answer solely through experimental assays. Therefore, we employed an established photosynthesis model. Firstly, we utilized the model to simulate the measured rapid ChlF rise and P515 kinetics simultaneously. Secondly, we employed the sensitivity analysis (SA) tool by randomly altering model parameters to observe their effects on model output variables. Thirdly, we systematically identified significant parameters for both or one of the kinetics across various scenarios. A novel aspect of our study is the application of the Morris method, a global SA tool, to simultaneously assess the significance of model parameters in shaping both or one of the kinetics. The Morris SA technique enables the quantification of how much a specific parameter affects O-J-I-P transient during particular time intervals (e.g., J, I, and P steps). This allowed us to theoretically analyze which step is more significantly influenced by the parameter. In summary, our study contributes to the field by providing a comprehensive analysis of photosynthesis kinetics and emphasizing the importance of parameter selection in modelling this process. These findings can inform future research efforts aimed at improving photosynthesis models and advancing our understanding of photosynthetic processes., (© 2024 Scandinavian Plant Physiology Society.)

To keep up with the growth of human population and to circumvent deleterious effects of global climate change, it is essential to enhance crop yield to achieve higher production. Here we review mathematical models of oxygenic photosynthesis that are extensively used, and discuss in depth a subset that accounts for diverse approaches providing solutions to our objective. These include models (1) to study different ways to enhance photosynthesis, such as fine-tuning antenna size, photoprotection and electron transport; (2) to bioengineer carbon metabolism; and (3) to evaluate the interactions between the process of photosynthesis and the seasonal crop dynamics, or those that have included statistical whole-genome prediction methods to quantify the impact of photosynthesis traits on the improvement of crop yield. We conclude by emphasizing that the results obtained in these studies clearly demonstrate that mathematical modelling is a key tool to examine different approaches to improve photosynthesis for better productivity, while effective multiscale crop models, especially those that also include remote sensing data, are indispensable to verify different strategies to obtain maximized crop yields., (© 2024. The Author(s), under exclusive licence to Springer Nature B.V.)

Plants have evolved multiple regulatory mechanisms to cope with natural light fluctuations. The interplay between these mechanisms leads presumably to the resilience of plants in diverse light patterns. We investigated the energy-dependent nonphotochemical quenching (qE) and cyclic electron transports (CET) in light that oscillated with a 60-s period with three different amplitudes. The photosystem I (PSI) and photosystem II (PSII) function-related quantum yields and redox changes of plastocyanin and ferredoxin were measured in Arabidopsis thaliana wild types and mutants with partial defects in qE or CET. The decrease in quantum yield of qE due to the lack of either PsbS- or violaxanthin de-epoxidase was compensated by an increase in the quantum yield of the constitutive nonphotochemical quenching. The mutant lacking NAD(P)H dehydrogenase (NDH)-like-dependent CET had a transient significant PSI acceptor side limitation during the light rising phase under high amplitude of light oscillations. The mutant lacking PGR5/PGRL1-CET restricted electron flows and failed to induce effective photosynthesis control, regardless of oscillation amplitudes. This suggests that PGR5/PGRL1-CET is important for the regulation of PSI function in various amplitudes of light oscillation, while NDH-like-CET acts' as a safety valve under fluctuating light with high amplitude. The results also bespeak interplays among multiple photosynthetic regulatory mechanisms., (© 2024 The Authors. Plant, Cell & Environment published by John Wiley & Sons Ltd.)

Despite the need for quantitative measurements of light intensity across many scientific disciplines, existing technologies for measuring light dose at the sample of a fluorescence microscope cannot simultaneously retrieve light intensity along with spatial distribution over a wide range of wavelengths and intensities. To address this limitation, we developed two rapid and straightforward protocols that use organic dyes and fluorescent proteins as actinometers. The first protocol relies on molecular systems whose fluorescence intensity decays and/or rises in a monoexponential fashion when constant light is applied. The second protocol relies on a broad-absorbing photochemically inert fluorophore to back-calculate the light intensity from one wavelength to another. As a demonstration of their use, the protocols are applied to quantitatively characterize the spatial distribution of light of various fluorescence imaging systems, and to calibrate illumination of commercially available instruments and light sources., (© 2023. The Author(s).)

In natural environments, plants are exposed to rapidly changing light. Maintaining photosynthetic efficiency while avoiding photodamage requires equally rapid regulation of photoprotective mechanisms. We asked what the operation frequency range of regulation is in which plants can efficiently respond to varying light. Chlorophyll fluorescence, P700, plastocyanin, and ferredoxin responses of wild-types Arabidopsis thaliana were measured in oscillating light of various frequencies. We also investigated the npq1 mutant lacking violaxanthin de-epoxidase, the npq4 mutant lacking PsbS protein, and the mutants crr2-2, and pgrl1ab impaired in different pathways of the cyclic electron transport. The fastest was the PsbS-regulation responding to oscillation periods longer than 10 s. Processes involving violaxanthin de-epoxidase dampened changes in chlorophyll fluorescence in oscillation periods of 2 min or longer. Knocking out the PGR5/PGRL1 pathway strongly reduced variations of all monitored parameters, probably due to congestion in the electron transport. Incapacitating the NDH-like pathway only slightly changed the photosynthetic dynamics. Our observations are consistent with the hypothesis that nonphotochemical quenching in slow light oscillations involves violaxanthin de-epoxidase to produce, presumably, a largely stationary level of zeaxanthin. We interpret the observed dynamics of photosystem I components as being formed in slow light oscillations partially by thylakoid remodeling that modulates the redox rates., (© 2023 The Authors. New Phytologist © 2023 New Phytologist Foundation.)

The light-induced transthylakoid membrane potential (ΔΨ) can not only drive the ATP synthesis through the ATP-synthase in chloroplasts but serve as an essential modifier in the acclimation of photosynthesis to fluctuating light conditions. It has been manifested that during photosynthesis, the light-induced ΔΨ is responsive to multiple factors among which the ion channels/transporters (e.g., V-K + , VCCN1, and KEA3) are key to adjust the ion distribution on the two sides of the thylakoid membrane and hence shape the kinetics of ΔΨ. However, an in-depth mechanistic understanding of ion fluxes on adjusting the transthylakoid electric potentials is still unclear. This lack of a mechanistic understanding is due to the experimental difficulty of closely observing ion fluxes in vivo and also hacking the evolution of parameters in a highly intertwined photosynthetic network. In this work, a computer model was applied to investigate the roles of ion fluxes on adjusting transthylakoid electric potentials upon a temporal cycle of a period of high illumination followed by a dark-adapted phase. The computing data revealed that, firstly, upon illumination, the dissipation of the steady-ΔΨ by ∼10 mV is contributed from the V-K + -driven K + flux whilst ∼8 mV of the steady-ΔΨ is dissipated by the VCCN1-pumped Cl - flux, but there were no appreciable KEA3-evoked variations on ΔΨ; secondly, on transition from high light to darkness, V-K + and KEA3 are serving as major contributors whereas VCCN1 taking a counterbalancing part in shaping a standard trace of ECS (electrochromic shift), which commonly shows a sharp fall to a minimum before returning to the baseline in darkness. Besides, the functional consequences on components of ΔΨ adjusted by every particular ion channel/transporter were also explored. By employing the model, we bring evidence that particular thylakoid-harbored proteins, namely V-K + , VCCN1, and KEA3, function by distinct mechanisms in the dynamic adjustment of electric potential, which might be mainly importnat under fluctuating light conditions., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier Masson SAS. All rights reserved.)

Plants growing in nature often experience fluctuating irradiance. However, in the laboratory, the dynamics of photosynthesis are usually explored by instantaneously exposing dark-adapted plants to constant light and examining the dark-to-light transition, which is a poor approximation of natural phenomena. With the aim creating a better approximation, we exposed leaves of pea (Pisum sativum) to oscillating light and measured changes in the functioning of PSI and PSII, and of the proton motive force at the thylakoid membrane. We found that the dynamics depended on the oscillation period, revealing information about the underlying regulatory networks. As demonstrated for a selected oscillation period of 60 s, the regulation tries to keep the reaction centers of PSI and PSII open. We present an evaluation of the data obtained, and discuss the involvement of particular processes in the regulation of photosynthesis. The forced oscillations provided an information-rich fingerprint of complex regulatory networks. We expect future progress in understanding these networks from experiments involving chemical interventions and plant mutants, and by using mathematical modeling and systems identification and control tools., (© The Author(s) 2022. Published by Oxford University Press on behalf of the Society for Experimental Biology.)

The transthylakoid membrane potential (ΔΨ m ) is essential because it can drive the ATP synthesis through the CF 0 -CF 1 type of ATP-synthase in chloroplasts as an energetic equivalent similar to ΔpH. In addition, a high fraction of proton motive force (PMF) stored as the ΔΨ m component is physiologically important in the acclimation of photosynthesis to environmental stresses. It has been shown that ΔΨ m is the sum of the Donnan potential difference (ΔΨ dn ) and the diffusion potential difference (ΔΨ d ). Specifically, ΔΨ dn , ΔΨ d , and ΔΨ m are strongly associated with the ionic activities near the membrane surface, particularly, the extent of ion binding to the charged/neutral sites adjacent to the membrane surface. However, an in-depth analysis of the effect of altered cationic binding to the membrane surface on adjusting the transthylakoid electric potentials (ΔΨ dn , ΔΨ d , and ΔΨ m ) is still missing. This lack of a mechanistic understanding is due to the experimental difficulty of closely observing cations binding to the membrane surface in vivo . In this work, a computer model was proposed to investigate the transthylakoid electric phenomena in the chloroplast focusing on the interaction between cations and the negative charges close to the membrane surface. By employing the model, we simulated the membrane potential and consequently, the measured ECS traces, proxing the ΔΨ m , were well described by the computing results on continuous illumination followed by a dark-adapted period. Moreover, the computing data clarified the components of transthylakoid membrane potential, unraveled the functional consequences of altered cationic attachment to the membrane surface on adjusting the transthylakoid electric potential, and further revealed the key role played by Donnan potential in regulating the energization of the thylakoid membrane. The current model for calculating electric potentials can function as a preliminary network for the further development into a more detailed theoretical model by which multiple important variables involved in photosynthesis can be explored., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Lyu and Lazár.)

The largest stable photosystem II (PSII) supercomplex in land plants (C2S2M2) consists of a core complex dimer (C2), two strongly (S2) and two moderately (M2) bound light-harvesting protein (LHCB) trimers attached to C2 via monomeric antenna proteins LHCB4-6. Recently, we have shown that LHCB3 and LHCB6, presumably essential for land plants, are missing in Norway spruce (Picea abies), which results in a unique structure of its C2S2M2 supercomplex. Here, we performed structure-function characterization of PSII supercomplexes in Arabidopsis (Arabidopsis thaliana) mutants lhcb3, lhcb6, and lhcb3 lhcb6 to examine the possibility of the formation of the "spruce-type" PSII supercomplex in angiosperms. Unlike in spruce, in Arabidopsis both LHCB3 and LHCB6 are necessary for stable binding of the M trimer to PSII core. The "spruce-type" PSII supercomplex was observed with low abundance only in the lhcb3 plants and its formation did not require the presence of LHCB4.3, the only LHCB4-type protein in spruce. Electron microscopy analysis of grana membranes revealed that the majority of PSII in lhcb6 and namely in lhcb3 lhcb6 mutants were arranged into C2S2 semi-crystalline arrays, some of which appeared to structurally restrict plastoquinone diffusion. Mutants without LHCB6 were characterized by fast induction of non-photochemical quenching and, on the contrary to the previous lhcb6 study, by only transient slowdown of electron transport between PSII and PSI. We hypothesize that these functional changes, associated with the arrangement of PSII into C2S2 arrays in thylakoids, may be important for the photoprotection of both PSI and PSII upon abrupt high-light exposure., (© The Author(s) 2021. Published by Oxford University Press on behalf of American Society of Plant Biologists.)

Foundations of photosynthesis research have been established mainly by studying the response of plants to changing light, typically to sudden exposure to a constant light intensity after dark acclimation or light flashes. This approach remains valid and powerful, but can be limited by requiring dark acclimation before time-domain measurements and often assumes that rate constants determining the photosynthetic response do not change between dark and light acclimation. We show that these limits can be overcome by measuring plant responses to sinusoidally modulated light of varying frequency. By its nature, such frequency-domain characterization is performed in light-acclimated plants with no need for prior dark acclimation. Amplitudes, phase shifts, and upper harmonic modulation extracted from the data for a wide range of frequencies can target different kinetic domains and regulatory feedbacks. The occurrence of upper harmonic modulation reflects nonlinear phenomena, including photosynthetic regulation. To support these claims, we measured chlorophyll fluorescence emission of the green alga Chlorella sorokiniana in light that was sinusoidally modulated in the frequency range 1000-0.001 Hz. Based on these experimental data and numerical as well as analytical mathematical models, we propose that frequency-domain measurements can become a versatile tool in plant sensing., (© American Society of Plant Biologists 2021. All rights reserved. For permissions, please email: journals.permissions@oup.com.)

Background: With limited agricultural land and increasing human population, it is essential to enhance overall photosynthesis and thus productivity. Oxygenic photosynthesis begins with light absorption, followed by excitation energy transfer to the reaction centres, primary photochemistry, electron and proton transport, NADPH and ATP synthesis, and then CO2 fixation (Calvin-Benson cycle, as well as Hatch-Slack cycle). Here we cover some of the discoveries related to this process, such as the existence of two light reactions and two photosystems connected by an electron transport 'chain' (the Z-scheme), chemiosmotic hypothesis for ATP synthesis, water oxidation clock for oxygen evolution, steps for carbon fixation, and finally the diverse mechanisms of regulatory processes, such as 'state transitions' and 'non-photochemical quenching' of the excited state of chlorophyll a., Scope: In this review, we emphasize that mathematical modelling is a highly valuable tool in understanding and making predictions regarding photosynthesis. Different mathematical models have been used to examine current theories on diverse photosynthetic processes; these have been validated through simulation(s) of available experimental data, such as chlorophyll a fluorescence induction, measured with fluorometers using continuous (or modulated) exciting light, and absorbance changes at 820 nm (ΔA820) related to redox changes in P700, the reaction centre of photosystem I., Conclusions: We highlight here the important role of modelling in deciphering and untangling complex photosynthesis processes taking place simultaneously, as well as in predicting possible ways to obtain higher biomass and productivity in plants, algae and cyanobacteria., (© The Author(s) 2019. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Lichens are symbiotic organisms that are well adapted to desiccation/rehydration cycles. Over the last decades, the physiological background of their photosynthetic response-specifically activation of the protective mechanism during desiccation-has been studied at the level of photosystem II of the lichen photobiont by means of several biophysical methods. In our study, the effects of desiccation and low temperatures on chlorophyll fluorescence and spectral reflectance parameters were investigated in Antarctic chlorolichen Dermatocarpon polyphyllizum. Lichen thalli were collected from James Ross Island, Antarctica, and following transfer to a laboratory, samples were fully hydrated and exposed to desiccation at temperatures of 18, 10, and 4 °C. During the desiccation process, the relative water content (RWC) was measured gravimetrically and photosynthetic parameters related to the fast transient of chlorophyll fluorescence (OJIP) were measured repeatedly. Similarly, the change in spectral reflectance parameters (e.g., NDVI, PRI, G, NPCI) was monitored during thallus dehydration. The dehydration-response curves showed a decrease in a majority of the OJIP-derived parameters (e.g., maximum quantum yield of photosystem II photochemistry: F V /F M , and performance index: PI in D. polyphyllizum, which were more apparent at RWCs below 20%. The activation of protective mechanisms in severely dehydrated thalli was documented by increased thermal dissipation (DI 0 /RC) and its quantum yield (Phi&#95;D 0 ). Low temperature accelerated these processes. An analysis of the OJIP shape reveals the presence of K-bands (300 μs), and L-bands (80 μs), which can be attributed to dehydration-induced stress. Spectral reflectance indices decreased in a majority of cases with an RWC decrease and were positively related to the OJIP-derived parameters: F V /F M (capacity of photosynthetic processes in PSII), Phi&#95;E 0 (effectiveness of electron transport), and PI&#95;tot (total performance index), which was more apparent in NDVI. A negative relation was found for NPCI. These indices could be used in follow-up ecophysiological photosynthetic studies of lichens that are undergoing rehydration/dehydration cycles.

Recent studies have shown that chlorophyll (Chl) b has an important role in the regulation of leaf senescence. However, there is only limited information about senescence of plants lacking Chl b and senescence-induced decrease in photosystem II (PSII) and photosystem I (PSI) function has not even been investigated in such plants. We have studied senescence-induced changes in photosynthetic pigment content and PSII and PSI activities in detached leaves of Chl b-deficient barley mutant, chlorina f2 f2 (clo). After 4 days in the dark, the senescence-induced decrease in PSI activity was smaller in clo compared to WT leaves. On the contrary, the senescence-induced impairment in PSII function (estimated from Chl fluorescence parameters) was much more pronounced in clo leaves, even though the relative decrease in Chl content was similar to wild type (WT) leaves (Hordeum vulgare L., cv. Bonus). The stronger impairment of PSII function seems to be related to more pronounced damage of reaction centers of PSII. Interestingly, exogenously applied plant hormone cytokinin 6-benzylaminopurine (BA) was able to maintain PSII function in the dark senescing clo leaves to a similar extent as in WT. Thus, considering the fact that without BA the senescence-induced decrease in PSII photochemistry in clo was more pronounced than in WT, the relative protective effect of BA was higher in Chl b-deficient mutant than in WT., (Copyright © 2019 Elsevier Masson SAS. All rights reserved.)