Storage and recall of environmental signals in a plant: modelling by use of a differential (continuous) formulation

Cellular metabolic activity is a highly complex, dynamic, regulated process that is influenced by numerous factors, including extracellular environmental signals, nutrient availability and the physiological and developmental status of the cell. The causative agent of sleeping sickness, Trypanosoma brucei, is an exclusively extracellular protozoan parasite that encounters very different extracellular environments during its life cycle within the mammalian host and tsetse fly insect vector. In order to meet these challenges, there are significant alterations in the major energetic and metabolic pathways of these highly adaptable parasites. This review highlights some of these metabolic changes in this early divergent eukaryotic model organism.

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The MarR-Type Regulator PA3458 Is Involved in Osmoadaptation Control in Pseudomonas aeruginosa

International Journal of Molecular Sciences ◽

10.3390/ijms22083982 ◽

2021 ◽

Vol 22 (8) ◽

pp. 3982

Author(s):

Karolina Kotecka ◽

Adam Kawalek ◽

Kamil Kobylecki ◽

Aneta Agnieszka Bartosik

Keyword(s):

Pseudomonas Aeruginosa ◽

Binding Sites ◽

Transcriptional Profiling ◽

Mrna Level ◽

Transcriptional Regulators ◽

Resistance Mechanisms ◽

Chronic Infections ◽

Environmental Signals ◽

Regulatory Systems

Pseudomonas aeruginosa is a facultative human pathogen, causing acute and chronic infections that are especially dangerous for immunocompromised patients. The eradication of P. aeruginosa is difficult due to its intrinsic antibiotic resistance mechanisms, high adaptability, and genetic plasticity. The bacterium possesses multilevel regulatory systems engaging a huge repertoire of transcriptional regulators (TRs). Among these, the MarR family encompasses a number of proteins, mainly acting as repressors, which are involved in response to various environmental signals. In this work, we aimed to decipher the role of PA3458, a putative MarR-type TR from P. aeruginosa. Transcriptional profiling of P. aeruginosa PAO1161 overexpressing PA3458 showed changes in the mRNA level of 133 genes; among them, 100 were down-regulated, suggesting the repressor function of PA3458. Concomitantly, ChIP-seq analysis identified more than 300 PA3458 binding sites in P. aeruginosa. The PA3458 regulon encompasses genes involved in stress response, including the PA3459–PA3461 operon, which is divergent to PA3458. This operon encodes an asparagine synthase, a GNAT-family acetyltransferase, and a glutamyl aminopeptidase engaged in the production of N-acetylglutaminylglutamine amide (NAGGN), which is a potent bacterial osmoprotectant. We showed that PA3458-mediated control of PA3459–PA3461 expression is required for the adaptation of P. aeruginosa growth in high osmolarity. Overall, our data indicate that PA3458 plays a role in osmoadaptation control in P. aeruginosa.

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Versatile Physiological Functions of Plant GSK3-Like Kinases

Genes ◽

10.3390/genes12050697 ◽

2021 ◽

Vol 12 (5) ◽

pp. 697

Author(s):

Juan Mao ◽

Wenxin Li ◽

Jing Liu ◽

Jianming Li

Keyword(s):

Stress Responses ◽

Glycogen Synthase ◽

Plant Stress ◽

Normal Growth ◽

Growth Conditions ◽

Genetic Studies ◽

Physiological Functions ◽

Environmental Signals ◽

Plant Stress Responses ◽

Diverse Plant

The plant glycogen synthase kinase 3 (GSK3)-like kinases are highly conserved protein serine/threonine kinases that are grouped into four subfamilies. Similar to their mammalian homologs, these kinases are constitutively active under normal growth conditions but become inactivated in response to diverse developmental and environmental signals. Since their initial discoveries in the early 1990s, many biochemical and genetic studies were performed to investigate their physiological functions in various plant species. These studies have demonstrated that the plant GSK3-like kinases are multifunctional kinases involved not only in a wide variety of plant growth and developmental processes but also in diverse plant stress responses. Here we summarize our current understanding of the versatile physiological functions of the plant GSK3-like kinases along with their confirmed and potential substrates.

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Striking forest revival at the end of the Roman Period in north-western Europe

Scientific Reports ◽

10.1038/s41598-020-77253-1 ◽

2020 ◽

Vol 10 (1) ◽

Author(s):

C. Lambert ◽

A. Penaud ◽

M. Vidal ◽

C. Gandini ◽

L. Labeyrie ◽

...

Keyword(s):

North Atlantic ◽

Western Europe ◽

Anthropogenic Activities ◽

Sedimentary Environment ◽

Pollen Grains ◽

Roman Period ◽

Freshwater Microalgae ◽

Environmental Signals ◽

The North ◽

North Western

AbstractThe Holocene period (last 11,700 years BP) has been marked by significant climate variability over decadal to millennial timescales. The underlying mechanisms are still being debated, despite ocean–atmosphere–land connections put forward in many paleo-studies. Among the main drivers, involving a cluster of spectral signatures and shaping the climate of north-western Europe, are solar activity, the North Atlantic Oscillation (NAO) varying atmospheric regimes and North Atlantic oceanic gyre dynamics. Over the last 2500 years BP, paleo-environmental signals have been strongly affected by anthropogenic activities through deforestation and land use for crops, grazing, habitations, or access to resources. Palynological proxies (especially pollen grains and marine or freshwater microalgae) help to highlight such anthropogenic imprints over natural variability. Palynological analyses conducted in a macro-estuarine sedimentary environment of north-western France over the last 2500 years BP reveal a huge and atypical 300 year-long arboreal increase between 1700 and 1400 years BP (around 250 and 550 years AD) that we refer to as the ‘1.7–1.4 ka Arboreal Pollen rise event’ or ‘1.7–1.4 ka AP event’. Interestingly, the climatic 1700–1200 years BP interval coincides with evidence for the withdrawal of coastal societies in Brittany (NW France), in an unfavourable socio-economic context. We suggest that subpolar North Atlantic gyre strengthening and related increasing recurrence of storminess extremes may have affected long-term coastal anthropogenic trajectories resulting in a local collapse of coastal agrarian societies, partly forced by climatic degradation at the end of the Roman Period.

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The Craterostigma plantagineum protein kinase CpWAK1 interacts with pectin and integrates different environmental signals in the cell wall

Planta ◽

10.1007/s00425-021-03609-0 ◽

2021 ◽

Vol 253 (5) ◽

Author(s):

Peilei Chen ◽

Valentino Giarola ◽

Dorothea Bartels

Keyword(s):

Cell Wall ◽

Stress Responses ◽

Expression Profiles ◽

Phylogenetic Analyses ◽

Cell Wall Protein ◽

Biological Processes ◽

Environmental Signals ◽

High Affinity ◽

Craterostigma Plantagineum ◽

Receptor Kinases

Abstract Main conclusion The cell wall protein CpWAK1 interacts with pectin, participates in decoding cell wall signals, and induces different downstream responses. Abstract Cell wall-associated protein kinases (WAKs) are transmembrane receptor kinases. In the desiccation-tolerant resurrection plant Craterostigma plantagineum, CpWAK1 has been shown to be involved in stress responses and cell expansion by forming a complex with the C. plantagineum glycine-rich protein1 (CpGRP1). This prompted us to extend the studies of WAK genes in C. plantagineum. The phylogenetic analyses of WAKs from C. plantagineum and from other species suggest that these genes have been duplicated after species divergence. Expression profiles indicate that CpWAKs are involved in various biological processes, including dehydration-induced responses and SA- and JA-related reactions to pathogens and wounding. CpWAK1 shows a high affinity for “egg-box” pectin structures. ELISA assays revealed that the binding of CpWAKs to pectins is modulated by CpGRP1 and it depends on the apoplastic pH. The formation of CpWAK multimers is the prerequisite for the CpWAK–pectin binding. Different pectin extracts lead to opposite trends of CpWAK–pectin binding in the presence of Ca2+ at pH 8. These observations demonstrate that CpWAKs can potentially discriminate and integrate cell wall signals generated by diverse stimuli, in concert with other elements, such as CpGRP1, pHapo, Ca2+[apo], and via the formation of CpWAK multimers.

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ABA Metabolism and Homeostasis in Seed Dormancy and Germination

International Journal of Molecular Sciences ◽

10.3390/ijms22105069 ◽

2021 ◽

Vol 22 (10) ◽

pp. 5069

Author(s):

Naoto Sano ◽

Annie Marion-Poll

Keyword(s):

Seed Dormancy ◽

Current Knowledge ◽

Fine Tuning ◽

Environmental Signals ◽

Hormone Synthesis ◽

Control Seed ◽

Functional Relationships ◽

Aba Metabolism ◽

Natural Variations ◽

Germinating Seeds

Abscisic acid (ABA) is a key hormone that promotes dormancy during seed development on the mother plant and after seed dispersal participates in the control of dormancy release and germination in response to environmental signals. The modulation of ABA endogenous levels is largely achieved by fine-tuning, in the different seed tissues, hormone synthesis by cleavage of carotenoid precursors and inactivation by 8′-hydroxylation. In this review, we provide an overview of the current knowledge on ABA metabolism in developing and germinating seeds; notably, how environmental signals such as light, temperature and nitrate control seed dormancy through the adjustment of hormone levels. A number of regulatory factors have been recently identified which functional relationships with major transcription factors, such as ABA INSENSITIVE3 (ABI3), ABI4 and ABI5, have an essential role in the control of seed ABA levels. The increasing importance of epigenetic mechanisms in the regulation of ABA metabolism gene expression is also described. In the last section, we give an overview of natural variations of ABA metabolism genes and their effects on seed germination, which could be useful both in future studies to better understand the regulation of ABA metabolism and to identify candidates as breeding materials for improving germination properties.

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The Roles of Chromatin Accessibility in Regulating the Candida albicans White-Opaque Phenotypic Switch

Journal of Fungi ◽

10.3390/jof7010037 ◽

2021 ◽

Vol 7 (1) ◽

pp. 37

Author(s):

Mohammad N. Qasim ◽

Ashley Valle Arevalo ◽

Clarissa J. Nobile ◽

Aaron D. Hernday

Keyword(s):

Candida Albicans ◽

Cell Fate ◽

Cell Types ◽

Chromatin Accessibility ◽

Phenotypic Switching ◽

Phenotypic Switch ◽

Chromatin Remodelers ◽

Environmental Signals ◽

Cell Fate Decisions ◽

Simple Model System

Candida albicans, a diploid polymorphic fungus, has evolved a unique heritable epigenetic program that enables reversible phenotypic switching between two cell types, referred to as “white” and “opaque”. These cell types are established and maintained by distinct transcriptional programs that lead to differences in metabolic preferences, mating competencies, cellular morphologies, responses to environmental signals, interactions with the host innate immune system, and expression of approximately 20% of genes in the genome. Transcription factors (defined as sequence specific DNA-binding proteins) that regulate the establishment and heritable maintenance of the white and opaque cell types have been a primary focus of investigation in the field; however, other factors that impact chromatin accessibility, such as histone modifying enzymes, chromatin remodelers, and histone chaperone complexes, also modulate the dynamics of the white-opaque switch and have been much less studied to date. Overall, the white-opaque switch represents an attractive and relatively “simple” model system for understanding the logic and regulatory mechanisms by which heritable cell fate decisions are determined in higher eukaryotes. Here we review recent discoveries on the roles of chromatin accessibility in regulating the C. albicans white-opaque phenotypic switch.

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Dead-Time Compensation for the First-Order Dead-Time Processes: Towards a Broader Overview

Mathematics ◽

10.3390/math9131519 ◽

2021 ◽

Vol 9 (13) ◽

pp. 1519

Author(s):

Mikulas Huba ◽

Pavol Bistak ◽

Damir Vrancic ◽

Katarina Zakova

Keyword(s):

Degrees Of Freedom ◽

Dead Time ◽

Feedforward Control ◽

Structural Instability ◽

Smith Predictor ◽

Actual Process ◽

Delayed Systems ◽

First Order ◽

Plant Modelling ◽

Dead Time Compensation

The article reviews the results of a number of recent papers dealing with the revision of the simplest approaches to the control of first-order time-delayed systems. The concise introductory review is extended by an analysis of two discrete-time approaches to dead-time compensation control of stable, integrating, and unstable first-order dead-time processes including simple diagnostics of the model used and focusing on the possibility of simplified but reliable plant modelling. The first approach, based on the first historically known dead-time compensator (DTC) with possible dead-beat performance, is based on the reconstruction of the actual process variables and the compensation of input disturbances by an extended state observer (ESO). Such solutions play an important role both in a disturbance observer (DOB) based control and in an active disturbance rejection control (ADRC). The second approach considered comes from the Smith predictor with two degrees of freedom, which combines feedforward control with output disturbance reconstruction and compensation by the parallel plant model. It is shown that these two approaches offer advantageous properties in the case of actuator limitations, in contrast to the commonly used PID controllers. However, when applied to integrating and unstable first-order systems, the unconstrained and possibly unobservable output disturbance signal of the second solution must be eliminated from the control loop, due to the hidden structural instability of the Smith predictor-like solutions. The modified solutions, usually referred to as filtered Smith predictor (FSP), then no longer provide a disturbance signal and thus no longer fully fit into the concept of Industry 4.0, which is focused on further optimization, predictive maintenance in dynamic systems, diagnosis, fault detection and fault identification of dynamic processes and forms the basis for the digitalization of smart production. Nevertheless, the detailed analysis of the elimination of the unstable disturbance response mode is also worth mentioning in terms of other possible solutions. The application of both approaches to the control of a thermal process shows almost equivalent quality, but with different dependencies on the tuning parameters used. It is confirmed that a more detailed identification of the controlled process and the resulting higher complexity of the control algorithms does not necessarily lead to an increase in the resulting quality of the transients, which underlines the importance of the simplified plant modelling for practice.

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