Balanced Growth Conditions Research Articles

Денежно-кредитная политика России в 2024–2026 годах: будет продолжен курс на стабильность

The monetary policy of the Russian Federation in 2024–2026 will traditionally be aimed at protecting and ensuring the stability of the ruble by maintaining price stability, which is a necessary condition for economic development, including the formation of conditions for balanced and sustainable economic growth.

Continuous polyhydroxybutyrate production from biogas in an innovative two-stage bioreactor configuration.

Biogas biorefineries have opened up new horizons beyond heat and electricity production in the anaerobic digestion sector. Added-value products such as polyhydroxyalkanoates (PHAs), which are environmentally benign and potential candidates to replace conventional plastics, can be generated from biogas. This work investigated the potential of an innovative two-stage growth-accumulation system for the continuous production of biogas-based polyhydroxybutyrate (PHB) using Methylocystis hirsuta CSC1 as cell factory. The system comprised two turbulent bioreactors in series to enhance methane and oxygen mass transfer: a continuous stirred tank reactor (CSTR) and a bubble column bioreactor (BCB) with internal gas recirculation. The CSTR was devoted to methanotrophic growth under nitrogen balanced growth conditions and the BCB targeted PHB production under nitrogen limiting conditions. Two different operational approaches under different nitrogen loading rates and dilution rates were investigated. A balanced nitrogen loading rate along with a dilution rate (D) of 0.3 day-1 resulted in the most stable operating conditions and a PHB productivity of ~53 g PHB m-3 day-1 . However, higher PHB productivities (~127 g PHB m-3 day-1 ) were achieved using nitrogen excess at a D = 0.2 day-1 . Overall, the high PHB contents (up to 48% w/w) obtained in the CSTR under theoretically nutrient balanced conditions and the poor process stability challenged the hypothetical advantages conferred by multistage vs single-stage process configurations for long-term PHB production.

Mathematical properties of optimal fluxes in cellular reaction networks at balanced growth.

The physiology of biological cells evolved under physical and chemical constraints, such as mass conservation across the network of biochemical reactions, nonlinear reaction kinetics, and limits on cell density. For unicellular organisms, the fitness that governs this evolution is mainly determined by the balanced cellular growth rate. We previously introduced growth balance analysis (GBA) as a general framework to model and analyze such nonlinear systems, revealing important analytical properties of optimal balanced growth states. It has been shown that at optimality, only a minimal subset of reactions can have nonzero flux. However, no general principles have been established to determine if a specific reaction is active at optimality. Here, we extend the GBA framework to study the optimality of each biochemical reaction, and we identify the mathematical conditions determining whether a reaction is active or not at optimal growth in a given environment. We reformulate the mathematical problem in terms of a minimal number of dimensionless variables and use the Karush-Kuhn-Tucker (KKT) conditions to identify fundamental principles of optimal resource allocation in GBA models of any size and complexity. Our approach helps to identify from first principles the economic values of biochemical reactions, expressed as marginal changes in cellular growth rate; these economic values can be related to the costs and benefits of proteome allocation into the reactions' catalysts. Our formulation also generalizes the concepts of Metabolic Control Analysis to models of growing cells. We show how the extended GBA framework unifies and extends previous approaches of cellular modeling and analysis, putting forward a program to analyze cellular growth through the stationarity conditions of a Lagrangian function. GBA thereby provides a general theoretical toolbox for the study of fundamental mathematical properties of balanced cellular growth.

Цветометрическая система мониторинга роста микроводоросли Dunaliella salina в лабораторных условиях

The brackish microalgae Dunaliella salina, being an extremophilic halophyte, is a promising object for biotechnological production. The aim of this work is to develop a methodology for non-destructive control of the development of a microalgae culture under conditions of balanced growth during periodic cultivation on plates. Before the start of the experiment, the microalgae culture was synchronized. The quantitative content of chlorophylls a and b, as well as carotenoids, was determined spectrophotometrically in alcohol extracts. During cultivation, time-lapse images were recorded on a smartphone camera. The basis of the colorimetric evaluation is the analysis of the time series of images in the RGB color model. It is shown that the ratio of colors correlates to a high degree with the content of the determined main plant pigments – chlorophylls and carotenoids, and with the data of spectrophotometric measurements of live suspensions. The changes in the blue channel are the most pronounced, the least being in the green channel. The logarithm of color intensity is linearly dependent on the degree of dilution of the culture. The developed method for real-time monitoring of the development dynamics of the D. salina microalgae culture makes it possible to build growth curves and solve multiparametric problems to optimize the cultivation of microalgae, including when working with large arrays of samples.

Ecophysiological response of marine copepods to dietary elemental imbalances

We assessed the effects of nutrient imbalanced diets on the feeding, reproduction and gross-growth efficiency of egg production of the copepod Paracartia grani. The cryptophyte Rhodomonas salina, cultivated under balanced (f/2) and imbalanced growth conditions (N and P limitation), served as prey. Copepod C:N and C:P ratios increased in the imbalanced treatments, particularly under P limitation. Feeding and egg production rates did not differ between the balanced and N-limited treatments but decreased under P limitation. We found no evidence of compensatory feeding in P. grani. C gross-growth efficiency averaged 0.34 in the balanced treatment and declined to values of 0.23 and 0.14 for the N- and P-limited treatments, respectively. Under N limitation, N gross-growth efficiency increased significantly to a mean value of 0.69, likely as a result of increasing the nutrient absorption efficiency. P gross-growth efficiency reached values > 1 under P limitation, involving the depletion of body P. Hatching success was >80%, with no differences among diets. Hatched nauplii, however, had lower size and slower development when the progenitor was fed a P-limited diet. This study highlights the effects of P limitation in copepods, which are more constraining than N, and the presence of maternal effects driven by prey nutritional composition that ultimately may affect population fitness.

Modeling Cell Size Distribution With Heterogeneous Flux Balance Analysis

For over two decades, Flux Balance Analysis (FBA) has been successfully used for predicting growth rates and intracellular reaction rates in microbiological metabolism. An aspect that is often omitted from this analysis, is segregation or heterogeneity between different cells. In this work, we propose an extended FBA method to model cell size distributions in balanced growth conditions. Hereto, a mathematical description of the concept of balanced growth in terms of cell mass distribution is presented. The cell mass distribution, quantified by the Number Density Function (NDF), is affected by cell growth and cell division. An optimization program is formulated in a general manner in which the NDF, average cell culture growth rate and reaction rates per cell mass are treated as optimization variables. As qualitative proof of concept, the methodology is illustrated on a core carbon model of Escherichia coli under aerobic growth conditions. This illustrates feasibility and applications of this method, while indicating some shortcomings intrinsic to the simplified biomass structuring and the time invariant approach.

Minimum nitrogen cell quota for maximal growth rate in cycloturbidostat cultures of Picochlorum oklahomense

Replicate cycloturbidostats cultures of Picochlorum oklahomense were manipulated to quantify the minimum nitrogen cell quota supporting maximum growth rate and to study the effects of nitrogen limitation on cycloturbidostat cultures growing at near-μmax under steady-state, balanced growth conditions. Results show that cyclical diurnal neutral lipid accumulation and ultradian growth are not mutually exclusive, and that cycloturbidostat cultures may be maintained near or at the threshold of N-limitation to control cell composition and modulate biomass and lipid productivity. Using this novel approach, we have identified the threshold of N limitation in P. oklahomense and investigated the effects of N limitation on replicate cycloturbidostat cultures. Mildly N-limited cultures grew rapidly (87 % μmax) and maintained near optimal physiology, while also accumulating neutral lipids during the photoperiod. Flow cytometry revealed differences in temporal patterns between treatments, demonstrating the importance of the cell-based approach in manipulating microalgal cultures. This study highlights the utility of turbidostats in experimental phycology and defines a scantly explored concept in the study of N limitation, the threshold of N cell quota necessary to support μmax below which cells are forced to re-allocate resources and slow growth, denoted QN, T.

Development of in silico strategies to photoautotrophically produce poly-β-hydroxybutyrate (PHB) by cyanobacteria

Poly(3-hydroxybutyrate) (PHB), a biopolymer similar to polypropylene, is currently produced by heterotrophic bacteria. However, the elevated cost of raw material used as carbon and energy sources are promoting the development of new sustainable bioprocess based on photoautotrophic routes costs. In unbalanced growth conditions, some cyanobacteria can accumulate PHB using CO2 as the sole carbon source, becoming an option for PHB production. In this work, we study in silico PHB production with the model cyanobacterium Synechocystis sp. PCC 6803 (Synechocystis). We consider two different strategies for in silico strain design: coupled growth-PHB production and a two-stage fermentation strategy. For both strategies we consider a GEnome-scale Model (GEM) of Synechocystis, which was modified to account for PHB production. The coupled approach relies on a bilevel optimization problem that identifies gene knock-outs needed to obtain a mutant that couples PHB production with biomass formation. For this case, two mutants that successfully achieve the required coupling are obtained, and the best one is analyzed in terms of intervention strategies, flux distributions and productivities. For the two-stage fermentation strategy, we consider two bioreactors in series. The first one is optimized for biomass production under balanced growth conditions, and the second one is optimized for PHB production under nitrogen starvation conditions. Both stages are simulated within dfba, a python tool for solving the Dynamic Flux Balance Analysis (DFBA) problem which provides the solution of a bioreactor model subject to the mass balances of the GEM. Numerical results for the two-stage approach provide a PHB concentration of 4.764 g PHB/L while the mutant provides a lower concentration of 0.391 g PHB/L. Nevertheless, both strategies provide high PHB content per cell dry weight (cdw), which makes results attractive for photosynthetic PHB production.

The impact of universal recycling on the evolution of economic diversity

Based on von Neumann's model of an economy characterized by processes and goods, we add to that model a component representing capital equipment. We assume that the need for capital equipment by any process is proportional to the rate at which that process is running, and therefore an increase in rate requires that capital equipment be purchased, whereas a decrease in rate allows capital equipment to be sold. We thereby construct a continuous-time dynamical model, which we use to investigate the evolution of economic diversity under two price equilibrium scenarios: the first with non-negative prices and non-positive excess demands; the second with enforced market clearing and with prices allowed to be negative. The second scenario represents an economy in which recycling is required, so that excess supply cannot be discarded. We prove that at any time during the progression of the model economy, the solution to each of the two price equilibrium problems exists, and that non-uniqueness of the solution, if any, does not affect the development of the model economy. We compare matched model economies under the two scenarios by simulating their respective evolutions. In each case, the model economy experiences a process of selection and matures to a state of balanced growth, with a higher growth rate when excess supply is discarded, but with greater economic diversity with enforced recycling. The robustness of these qualitative results is demonstrated by repeated trials of simulations on matched pairs of model economies with different randomly chosen parameters.

The Photophysiological Response of Nitrogen-Limited Phytoplankton to Episodic Nitrogen Supply Associated With Tropical Instability Waves in the Equatorial Atlantic

In the Equatorial Atlantic nitrogen availability is assumed to control phytoplankton dynamics. However, in situ measurements of phytoplankton physiology and productivity are surprisingly sparse in comparison with the North Atlantic. In addition to the formation of the Equatorial cold tongue in the boreal summer, tropical instability waves (TIWs) and related short-term processes may locally cause episodic events of enhanced nutrient supply to the euphotic layer. Here, we assess changes in phytoplankton photophysiology in response to such episodic events as well as short-term nutrient addition experiments using a pair of custom-built fluorometers that measure chlorophyll a (Chl a) variable fluorescence and fluorescence lifetimes. The fluorometers were deployed during a transatlantic cruise along the Equator in the fall of 2019. We hypothesized that the Equatorial Atlantic is nitrogen-limited, with an increasing degree of limitation to the west where the cold tongue is not prominent, and that infrequent nitrate injection by TIW related processes are the primary source alleviating this limitation. We further hypothesized phytoplankton are well acclimated to the low levels of nitrogen, and once nitrogen is supplied, they can rapidly utilize it to stimulate growth and productivity. Across three TIW events encountered, we observed increased productivity and chlorophyll a concentration concurrent with a decreased photochemical conversion efficiency and overall photophysiological competency. Moreover, the observed decrease in photosynthetic turnover rates toward the western section suggested a 70% decrease in growth rates compared to their maximum values under nutrient-replete conditions. This decrease aligned with the increased growth rates observed following 24 h incubation with added nitrate in the western section. These results support our hypotheses that nitrogen is the limiting factor in the region and that phytoplankton are in a state of balanced growth, waiting to “body surf” waves of nutrients which fuel growth and productivity.

A model for the relationship between plant biomass and photosynthetic rate based on nutrient effects

AbstractThe photosynthetic rate is considered to be affected by individual biomass and limited by nutrients. Metabolic scaling models are often utilized to predict photosynthetic rates based on plant size and other factors, such as temperature and plant nutrient composition. However, the intrinsic regulatory mechanisms of the combined factors that affect the photosynthetic rates of living organisms are subject to debate. Here, we present a model developed from the metabolic scaling model, the Michaelis‐Menten equation and elemental stoichiometric models to precisely predict the relationship between plant photosynthetic rate and biomass. The developed model was verified against data for small woody and nonwoody plants, and in comparison with the typical metabolic scaling model, this model was shown to be more capable of explaining the photosynthesis‐biomass relationship. Moreover, the results showed that the combined factors affected photosynthesis via the regulatory effect of nutrients on photosynthesis‐biomass allometry. We highlight that nutrients have direct effects on the allocation of plant biomass and photosynthetic investment under stable and balanced growth states.

Physiology and Transcriptional Analysis of (p)ppGpp-Related Regulatory Effects in Corynebacterium glutamicum.

The alarmone species ppGpp and pppGpp are elementary components of bacterial physiology as they both coordinate the bacterial stress response and serve as fine-tuners of general metabolism during conditions of balanced growth. Since the regulation of (p)ppGpp metabolism and the effects of (p)ppGpp on cellular processes are highly complex and show massive differences between bacterial species, the underlying molecular mechanisms have so far only been insufficiently investigated for numerous microorganisms. In this study, (p)ppGpp physiology in the actinobacterial model organism Corynebacterium glutamicum was analyzed by phenotypic characterization and RNAseq-based transcriptome analysis. Total nutrient starvation was identified as the most effective method to induce alarmone production, whereas traditional induction methods such as the addition of serine hydroxamate (SHX) or mupirocin did not show a strong accumulation of (p)ppGpp. The predominant alarmone in C. glutamicum represents guanosine tetraphosphate, whose stress-associated production depends on the presence of the bifunctional RSH enzyme Rel. Interestingly, in addition to ppGpp, another substance yet not identified accumulated strongly under inducing conditions. A C. glutamicum triple mutant (Δrel,ΔrelS,ΔrelH) unable to produce alarmones [(p)ppGpp0 strain] exhibited unstable growth characteristics and interesting features such as an influence of illumination on its physiology, production of amino acids as well as differences in vitamin and carotenoid production. Differential transcriptome analysis using RNAseq provided numerous indications for the molecular basis of the observed phenotype. An evaluation of the (p)ppGpp-dependent transcriptional regulation under total nutrient starvation revealed a complex interplay with the involvement of ribosome-mediated transcriptional attenuation, the stress-responsive sigma factors σB and σH and transcription factors such as McbR, the master regulator of sulfur metabolism. In addition to the differential regulation of genes connected with various cell functions, the transcriptome analysis revealed conserved motifs within the promoter regions of (p)ppGpp-dependently and independently regulated genes. In particular, the representatives of translation-associated genes are both (p)ppGpp-dependent transcriptionally downregulated and show a highly conserved and so far unknown TTTTG motif in the −35 region, which is also present in other actinobacterial genera.

Financial Security and Economic Growth

Financial security and economic growth the article analyzes aspects of creating conditions for sustainable and balanced economic growth in Russia, considering factors of the development of scientific and technological progress and financial security. It uses a systems approach and system analysis. As a result, the article gives recommendations on ensuring financial security and sustainable economic growth in Russia.

Target of rapamycin, a master regulator of multiple signalling pathways and a potential candidate gene for crop improvement

The target of rapamycin (TOR) protein regulates growth and development in photosynthetic and non-photosynthetic eukaryotes. Although the TOR regulatory networks are involved in nutrient and energy signalling, and transcriptional and translational control of multiple signalling pathways, the molecular mechanism of TOR regulation of plant abiotic stress responses is still unclear. The TOR-mediated transcriptional regulation of genes encoding ribosomal proteins (RP) is a necessity under stress conditions for balanced growth and productivity in plants. The activation of SnRKs (sucrose non-fermenting-related kinases) and the inactivation of TOR signalling in abiotic stresses is in line with the accumulation of ABA and transcriptional activation of stress responsive genes. Autophagy is induced under abiotic stress conditions, which results in degradation of proteins and the release of amino acids, which might possibly induce phosphorylation of TOR and, hence, its activation. TOR signalling also has a role in regulating ABA biosynthesis for transcriptional regulation of stress-related genes. The switch between activation and inactivation of TOR by its phosphorylation and de-phosphorylation maintains balanced growth in response to stresses. In the present review, we discuss the important signalling pathways that are regulated by TOR and try to assess the relationship between TOR signalling and tolerance to abiotic stresses in plants. The review also discusses possible cross-talk between TOR and RP genes in response to abiotic stresses.

СЦЕНАРИИ РАЗВИТИЯ МИРОВОЙ ВАЛЮТНО-ФИНАНСОВОЙ СИСТЕМЫ: ВОЗМОЖНОСТИ И РИСКИ ДЛЯ РОССИИ

The fundamental re-organization of the world monetary and financial system, currently based on the US dollar, is necessary prerequisite for creating conditions for stable, sustainable and balanced growth of the world economy. Using the method of scenario analysis, the authors consider four possible options for long-term development of the world monetary and financial system. Their implementation depends on prevailing expectations in the society regarding the strengthening or weakening of regulation of monetary relations, the concentration or dispersion of control over monetary authorities. The first scenario “supranational money” involves the introduction of a global reserve currency operated beyond the jurisdiction of any particular country. This scenario is based on the transformation of the IMF into a bank of central banks, conversion of SDRs into a systemic standard of value, introduction of symmetric rights and obligations between creditors and debtors to finance payment imbalances, transition to real rather than nominal fixed exchange rates, re-direction of virtual capital flows to priority service of real sector of the economy, creating a liquid market for SDR-denominated bonds. The analysis of viability of “gold re-monetization” scenario stems from comparison of the views of leading American economists on the prospects of restoring various forms of the gold standard – from the classical one with reestablishing of the monetary functions of gold to the quasi-golden variant realized through a 100% bank reserve system. In “monetary polycentrism” scenario the attention is drawn to the fact that introduction of the Euro failed to ensure financial sovereignty of the member countries of the Eurozone and to prevent economic destabilization of the European economic and monetary union. It is emphasized that the federalization of Europe in the banking, budgetary, fiscal and political spheres as well as intensive internationalization of Renminbi could serve as the basis for creating real alternatives to US dollar hegemony in the world, followed by the formation of currency blocks in Eurasia with the participation of Russia and China. In “digital currency” scenario the authors develop the hypothesis of using crypto currency (bitcoin and its analogues) for expanding the virtual market space in order to form a global financial cybernetic system that is not controlled by state organizations and transnational corporations. The authors come to the conclusion that Russia needs to seriously prepare for implementation of all analyzed scenarios while relying on its own historic experience in creating alternative international trading and monetary system.

Complementarity between energy and physical capital in a simple model of economic growth

Energy is one of the most important factors of growth, needed to power physical capital. This implies complementarity between these two factors, but in most theoretical papers, substitutability is assumed. In this paper, the main question is if complementarity between energy and physical capital hampers balanced growth or not. In order to answer this question, we consider the simple economic growth model with two sectors – output production and energy production – where energy is complementary to physical capital. Two forms of capital – physical and human – are distributed in this model between two sectors to maximise output. We consider the equilibrium state of this model, analyse comparative statics and derive necessary conditions for balanced growth. We also analyse some of the effects of technological progress. The analysis brings us to the conclusion that, in general, it leads to an increase in output, but that changes in technology of production have an ambiguous influence on output. We also derive explicit paths of growth for all macroeconomic variables. We find that, in general, if the obtained conditions are fulfilled then complementarity is not an obstacle to economic growth, subject to our assumptions which are quite standard in this kind of research.

Live fast, die fast principle in a single cell of fission yeast.

Growth and death are both fundamental macroscopic properties for all living matters, and thus cell division and mortality rates are good parameters for characterizing cellular physiology in a given environment. While population growth rates in various conditions have been reported in literature, death rate is rarely measured, especially in favorable culture conditions where cells grow exponentially. In our recent study (Nakaoka and Wakamoto, 2017), we developed a microfluidics-based platform to track multiple single cell lineages until death. The system enabled us to monitor both cell growth and death in controlled steady environments, and we confirmed the absence of replicative aging in fission yeast old-pole cell lineages by showing remarkable constancy both in cell division and mortality rates. Furthermore, we revealed a growth-death trade-off relation in non-stressed conditions. The phenomenological law that constrains macroscopic physiological parameters could provide a new quantitative insight into possible balanced-growth states in various environments.

Footprint area analysis of binary imaged Cupriavidus necator cells to study PHB production at balanced, transient, and limited growth conditions in a cascade process.

Statistical distribution of cell and poly[3-(R)-hydroxybutyrate] (PHB) granule size and number of granules per cell are investigated for PHB production in a five-stage cascade (5CSTR). Electron microscopic pictures of cells from individual cascade stages (R1–R5) were converted to binary pictures to visualize footprint areas for polyhydroxyalkanoate (PHA) and non-PHA biomass. Results for each stage were correlated to the corresponding experimentally determined kinetics (specific growth rate μ and specific productivity π). Log-normal distribution describes PHA granule size dissimilarity, whereas for R1 and R4, gamma distribution best reflects the situation. R1, devoted to balanced biomass synthesis, predominately contains cells with rather small granules, whereas with increasing residence time τ, maximum and average granule sizes by trend increase, approaching an upper limit determined by the cell’s geometry. Generally, an increase of intracellular PHA content and ratio of granule to cell area slow down along the cascade. Further, the number of granules per cell decreases with increasing τ. Data for μ and π obtained by binary picture analysis correlate well with the experimental results. The work describes long-term continuous PHA production under balanced, transient, and nutrient-deficient conditions, as well as their reflection on the granules size, granule number, and cell structure on the microscopic level.Electronic supplementary materialThe online version of this article (doi:10.1007/s00253-016-7844-6) contains supplementary material, which is available to authorized users.

Poly(3-hydroxybutyrate) anabolism inCupriavidus necatorcultivated at various carbon-to-nitrogen ratios: insights from single-cell Raman spectroscopy

Cupriavidus necator accumulates large amounts of poly(3-hydroxybutyrate) (PHB), a biodegradable substitute for petroleum-based plastics, under certain nutrient conditions. Conventional solvent-extraction-based methods for PHB quantification only obtain average information from cell populations and, thus, mask the heterogeneity among individual cells. Laser tweezers Raman spectroscopy (LTRS) was used to monitor dynamic changes in the contents of PHB, nucleic acids, and proteins in <italic<C. necator</italic< at the population and single-cell levels when the microorganism cells were cultivated at various carbon-to-nitrogen ratios. The biosynthetic activities of nucleic acids and proteins were maintained at high levels, and only a small amount of PHB was produced when the bacterial cells were cultured under balanced growth conditions. By contrast, the syntheses of nucleic acids and proteins were blocked, and PHB was accumulated in massive amount inside the microbial cells under nitrogen-limiting growth circumstances. Single-cell analysis revealed a relatively high heterogeneity in PHB level at the early stage of the bacterial growth. Additionally, bacterial cells in populations at certain cultivation stages were composed of two or three subpopulations on the basis of their PHB abundance. Overall, LTRS is a reliable single-cell analysis tool that can provide insights into PHB fermentation.

Investigation of Growth Mechanism and Role of H2 in Very Low Temperature Si Epitaxy

High quality crystalline homoepitaxial silicon film has been deposited in single-step growth using ultra-high vacuum plasma-enhanced chemical vapor deposition at 250°C. An investigation on the effects of key growth parameters such as temperature, hydrogen dilution, and plasma power has led to achievement of balanced growth conditions. Material Characterization reveals that the defect-free growth is due to the dominant role hydrogen plays in enhancing surface diffusion over selective etching of the amorphous phase. Absence of crystal defects, such as dislocations or stacking faults, shows that single-step growth, results in extremely high quality growth at low temperatures.