Erratum: Tran et al. Early Cellular Responses Induced by Sedimentary Calcite-Processed Particles in Bright Yellow 2 Tobacco Cultured Cells. Int. J. Mol. Sci. 2020, 21, 4279.

The authors would like to remove the scientific consortium 'Camille Nous' from the author list and the Author Contributions section in the published paper [...].

Early Cellular Responses Induced by Sedimentary Calcite-Processed Particles in Bright Yellow 2 Tobacco Cultured Cells.

Calcite processed particles (CaPPs, Megagreen®) elaborated from sedimentary limestone rock, and finned by tribomecanic process were found to increase photosynthetic CO2 fixation grapevines and stimulate growth of various cultured plants. Due to their processing, the CaPPs present a jagged shape with some invaginations below the micrometer size. We hypothesised that CaPPs could have a nanoparticle (NP)-like effects on plants. Our data show that CaPPs spontaneously induced reactive oxygen species (ROS) in liquid medium. These ROS could in turn induce well-known cellular events such as increase in cytosolic Ca2+, biotic ROS generation and activation of anion channels indicating that these CaPPs could activate various signalling pathways in a NP-like manner.

Enhanced elevations of hypo-osmotic shock-induced cytosolic and nucleic calcium concentrations in tobacco cells by pretreatment with dimethyl sulfoxide.

Dimethyl sulfoxide (DMSO) is a dipolar aprotic solvent widely used in biological assays. Here, we observed that DMSO enhanced the hypo-osmotically induced increases in the concentration of Ca2+ in cytosolic and nucleic compartments in the transgenic cell-lines of tobacco (BY-2) expressing aequorin.

Methanol induces cytosolic calcium variations, membrane depolarization and ethylene production in arabidopsis and tobacco.

Background and Aims: Methanol is a volatile organic compound released from plants through the action of pectin methylesterases (PMEs), which demethylesterify cell wall pectins. Plant PMEs play a role in developmental processes but also in responses to herbivory and infection by fungal or bacterial pathogens. However, molecular mechanisms that explain how methanol could affect plant defences remain poorly understood. Methods: Using cultured cells and seedlings from Arabidopsis thaliana and tobacco BY2 expressing the apoaequorin gene, allowing quantification of cytosolic Ca2+, a reactive oxygen species (ROS) probe (CLA, Cypridina luciferin analogue) and electrophysiological techniques, we followed early plant cell responses to exogenously supplied methanol applied as a liquid or as volatile. Key Results: Methanol induces cytosolic Ca2+ variations that involve Ca2+ influx through the plasma membrane and Ca2+ release from internal stores. Our data further suggest that these Ca2+ variations could interact with different ROS and support a signalling pathway leading to well known plant responses to pathogens such as plasma membrane depolarization through anion channel regulation and ethylene synthesis. Conclusions: Methanol is not only a by-product of PME activities, and our data suggest that [Ca2+]cyt variations could participate in signalling processes induced by methanol upstream of plant defence responses.

Effect of different light spectra on the pigmentation of stored elephant garlic.

BACKGROUND: In the present study high-brightness light-emitting diodes were used to investigate the influence of different light spectra on garlic discoloration at different humidity levels and temperature. Many processes involved in the discoloration process of garlic/leek during storage under different conditions remain unanswered. For this reason in this study the ability of specific light spectra to enhance the production of desirable pigments has been evaluated in elephant garlic. It is well known that the pigments involved in the discoloration reaction are of great interest because of their potential ability to increase the nutritional value and health benefits of the food. RESULTS: In the present study, we show how the chlorophyll content of the sprout increases directly proportionally to the wavelength of the light tested; green/blue light delays the greening process of garlic young shoots whilst red/infra-red light irradiance conditions increase the greening process at different storage temperatures and humidity. Moreover different lights in the visible spectrum have been observed to stimulate and enhance the outer layer purple coloration. CONCLUSION: The use of different lights to modulate garlic pigmentation has been demonstrated and, in particular, the utilisation of red/green/blue lights and lower temperature resulted in higher red/pink pigments production supporting the hypothesis that this process involves more than one light to be fully performed and the low temperature is a condition that influences the formation of these products. © 2017 Society of Chemical Industry.

Indole-3-acetic acid-induced oxidative burst and an increase in cytosolic calcium ion concentration in rice suspension culture.

Indole-3-acetic acid (IAA) is the major natural auxin involved in the regulation of a variety of growth and developmental processes such as division, elongation, and polarity determination in growing plant cells. It has been shown that dividing and/or elongating plant cells accompanies the generation of reactive oxygen species (ROS) and a number of reports have suggested that hormonal actions can be mediated by ROS through ROS-mediated opening of ion channels. Here, we surveyed the link between the action of IAA, oxidative burst, and calcium channel activation in a transgenic cells of rice expressing aequorin in the cytosol. Application of IAA to the cells induced a rapid and transient generation of superoxide which was followed by a transient increase in cytosolic Ca(2+) concentration ([Ca(2+)]c). The IAA-induced [Ca(2+)]c elevation was inhibited by Ca(2+) channel blockers and a Ca(2+) chelator. Furthermore, ROS scavengers effectively blocked the action of IAA on [Ca(2+)]c elevation.

Protection of tobacco cells from oxidative copper toxicity by catalytically active metal-binding DNA oligomers.

The impact of copper ions on the oxidative and calcium signal transductions, leading to cell death in plant cells, have been documented. Copper induces a series of biological and chemical reactions in plant cells including the oxidative burst reflecting the production of reactive oxygen species and the stimulation of calcium channel opening allowing a transient increase in cytosolic calcium concentrations. These early events, completed within a few minutes after the contact with copper, are known to trigger the development of cell death. The effects of DNA fragments with copper-binding motifs as novel plant cell-protecting agents were assessed using cell suspension cultures of transgenic tobacco (Nicotiana tabacum L., cell line BY-2) expressing the aequorin gene. The addition of GC-rich double-stranded DNA fragments, prior to the addition of copper ions, effectively blocked both the copper-induced calcium influx and cell death. In addition, the DNA-Cu complex examined was shown to possess superoxide-scavenging catalytic activity, suggesting that DNA-mediated protection of the cells from copper toxicity is due to the removal of superoxide. Lastly, a possible mechanism of DNA-Cu interaction and future applications of these DNA fragments in the protection of plant roots from metal toxicity or in aid of phyto-remediation processes are discussed.

Deciphering early events involved in hyperosmotic stress-induced programmed cell death in tobacco BY-2 cells.

Hyperosmotic stresses represent one of the major constraints that adversely affect plants growth, development, and productivity. In this study, the focus was on early responses to hyperosmotic stress- (NaCl and sorbitol) induced reactive oxygen species (ROS) generation, cytosolic Ca(2+) concentration ([Ca(2+)]cyt) increase, ion fluxes, and mitochondrial potential variations, and on their links in pathways leading to programmed cell death (PCD). By using BY-2 tobacco cells, it was shown that both NaCl- and sorbitol-induced PCD seemed to be dependent on superoxide anion (O2·(-)) generation by NADPH-oxidase. In the case of NaCl, an early influx of sodium through non-selective cation channels participates in the development of PCD through mitochondrial dysfunction and NADPH-oxidase-dependent O2·(-) generation. This supports the hypothesis of different pathways in NaCl- and sorbitol-induced cell death. Surprisingly, other shared early responses, such as [Ca(2+)]cyt increase and singlet oxygen production, do not seem to be involved in PCD.

Post-transcriptional regulation of GORK channels by superoxide anion contributes to increases in outward-rectifying K⁺ currents.

· Ion fluxes are ubiquitous processes in the plant and animal kingdoms, controlled by fine-tuned regulations of ion channel activity. Yet the mechanism that cells employ to achieve the modification of ion homeostasis at the molecular level still remains unclear. This is especially true when it comes to the mechanisms that lead to cell death. · In this study, Arabidopsis thaliana cells were exposed to ozone (O3). Ion flux variations were analyzed by electrophysiological measurements and their transcriptional regulation by RT-PCR. Reactive oxygen species (ROS) generation was quantified by luminescence techniques and caspase-like activities were investigated by laser confocal microscopy. · We highlighted the delayed activation of K(+) outward-rectifying currents after an O3 -induced oxidative stress leading to programmed cell death (PCD). Caspase-like activities are detected under O3 exposure and could be decreased by K(+) channel blocker. Molecular experiments revealed that the sustained activation of K(+) outward current could be the result of an unexpected O2 ·â» post-transcriptional regulation of the guard cell outward-rectifying K(+) (GORK) channels. · This consists of a likely new mode of regulating the processing of the GORK mRNA, in a ROS-dependent manner, to allow sustained K(+) effluxes during PCD. These data provide new mechanistic insights into K(+) channel regulation during an oxidative stress response.

A role for oxalic acid generation in ozone-induced signallization in Arabidopis cells.

Ozone (O(3) ) is an air pollutant with an impact increasingly important in our industrialized world. It affects human health and productivity in various crops. We provide the evidences that treatment of Arabidopsis thaliana with O(3) results in ascorbate-derived oxalic acid production. Using cultured cells of A. thaliana as a model, here we further showed that oxalic acid induces activation of anion channels that trigger depolarization of the cell, increase in cytosolic Ca(2+) concentration, generation of reactive oxygen species and cell death. We confirmed that O(3) reacts with ascorbate in the culture, thus resulting in production of oxalic acid and this could be part of the O(3) -induced signalling pathways that trigger programmed cell death.

Crosstalk between intracellular and extracellular salicylic acid signaling events leading to long-distance spread of signals.

It is well recognized that salicylic acid (SA) acts as a natural signaling molecule involved in both local and systemic plant defense responses upon attacks by pathogens. Recently, cellular SA receptors and a number of SA-related phloem-mobile signals were identified. Here, we compare the old and up-to-date concepts of plant defense signaling events involving SA. Finally, the crosstalk between intracellular and extracellular SA signaling events leading to long-distance spread of signals was outlined by focusing on the modes of both the short- and long-distance signaling events involving the actions of SA. For the above purpose, two distinct conceptual models for local SA perception and signaling mechanisms in the intracellular and extracellular paths (referred to as models i and ii, respectively) were proposed. In addition to two local SA perception models, we propose that the long-distance SA action could be attributed to three different modes, namely, (iii) local increase in SA followed by transport of SA and SA intermediates, (iv) systemic propagation of SA-derived signals with both chemical and electrical natures without direct movement of SA, and (v) integrated crosstalk allowing alternately repeated secondary signal propagation and biosynthesis of SA and/or conversion of inert SA intermediates to free SA finally contributing to the systemic spread of SA-derived signals. We review here that the long-distance SA signaling events (models iii-v), inevitably involve the mechanisms described in the local signaling models (models i and ii) as the key pieces of the crosstalk.

Selenium cannot substitute for sulfur in cell density-independent bioluminescence in Vibrio fischeri.

It has been proposed that selenium, an element chemically similar to sulfur, can participate in some of the same biological pathways as sulfur, although only a few studies have been confirmed this. In this study, we investigated the relationship between selenium and sulfur-dependent luminescence in Vibrio fischeri. The luminescence of V. fischeri was induced by the addition of sulfur-containing compounds such as Na2SO4 and L-cystine, and their luminescence was suppressed, in a dose-dependent manner, by the addition of the selenium-containing compounds Na2SeO4 and L-selenocystine. Since the viability of V. fischeri was not affected by the addition of low concentration of selenium-containing compounds, the decrease in luminescence intensity cannot be explained by cell death. Kinetic analysis performed using Lineweaver-Burk plots demonstrate that Na2SeO4 and L-selenocystine act as competitive suppressors in inorganic sulfur (Na2SeO4)-dependent luminescence. In contrast, these selenium-containing compounds act as uncompetitive suppressors in organic sulfur (L-cystine)-dependent luminescence.

Arsenic and Human Health: Genotoxicity, Epigenomic Effects, and Cancer Signaling.

Arsenic is a well-known element because of its toxicity. Humans as well as plants and animals are negatively affected by its exposure. Some countries suffer from high levels of arsenic in their tap water and soils, which is considered a primary arsenic-linked risk factor for living beings. Humans generally get exposed to arsenic by contaminated drinking waters, resulting in many health problems, ranging from cancer to skin diseases. On the other hand, the FDA-certified drug arsenic trioxide provides solutions for various diseases, including several types of cancers. This issue emphasizes the importance of speciation of the metalloid elements in terms of impacts on health. When species get exposed to arsenic, it affects the cells altering their involvement. It can lead to abnormalities in inflammatory mechanisms and the immune system which contribute to the negative impacts generated on the body. The poisoning originating from arsenic gives rise to various biological signs on the body which can be useful for the diagnosis. It is important to find true biomarkers for the detection of arsenic poisoning. In view of its application in medicine and biology, studies on understanding the biological activity of arsenic have increased. In this review, we aim at summarizing the current state of knowledge of arsenic and the mechanism behind its toxicity including genotoxicity, oxidative insults, epigenomic changes, and alterations in cellular signaling.

Prevention of oxidative DNA degradation by copper-binding peptides.

Free divalent ions of copper (Cu) are capable of generating radical species such as hydroxyl radicals in the presence of hydrogen peroxide or ascorbic acid through Harbor-Weiss-like reactions under physiological conditions. It has been reported that radical-mediated damage to DNA molecules in animal cells leads to programmed cell death. Hence it is important to seek for methods to prevent Cu-mediated DNA damage. In this study we identified on effect of Cu binding of short peptides (chiefly Gly-Gly-His tripeptide) in the prevention of DNA degradation caused by Cu-mediated reactions in the presence of hydrogen peroxide and of ascorbic acid.

Copper-binding peptides from human prion protein and newly designed peroxidative biocatalysts.

A previous work suggested that peptides from the histidine-containing copper-binding motifs in human prion protein (PrP) function as peroxidase-like biocatalysts catalyzing the generation of superoxide anion radicals in the presence of neurotransmitters (aromatic monoamines) and phenolics such as tyrosine and tyrosyl residues on proteins. In this study, using various phenolic substrates, the phenol-dependent superoxide-generating activities of PrP-derived peptide sequences were compared. Among the peptides tested, the GGGTH pentapeptide was shown to be the most active catalyst for phenol-dependent reactions. Based on these results, we designed a series of oligoglycyl-histidines as novel peroxidative biocatalysts, and their catalytic performances including kinetics, heat tolerance, and freezing tolerance were analysed.

Our sisters the plants? notes from phylogenetics and botany on plant kinship blindness.

Before the upheaval brought about by phylogenetic classification, classical taxonomy separated living beings into two distinct kingdoms, animals and plants. Rooted in 'naturalist' cosmology, Western science has built its theoretical apparatus on this dichotomy mostly based on ancient Aristotelian ideas. Nowadays, despite the adoption of the Darwinian paradigm that unifies living organisms as a kinship, the concept of the "scale of beings" continues to structure our analysis and understanding of living species. Our aim is to combine developments in phylogeny, recent advances in biology, and renewed interest in plant agency to craft an interdisciplinary stance on the living realm. The lines at the origin of plant or animal have a common evolutionary history dating back to about 3.9 Ga, separating only 1.6 Ga ago. From a phylogenetic perspective of living species history, plants and animals belong to sister groups. With recent data related to the field of Plant Neurobiology, our aim is to discuss some socio-cultural obstacles, mainly in Western naturalist epistemology, that have prevented the integration of living organisms as relatives, while suggesting a few avenues inspired by practices principally from other ontologies that could help overcome these obstacles and build bridges between different ways of connecting to life.

Molecular Biology of Cadmium Toxicity in Saccharomyces cerevisiae.

Cadmium (Cd) is a toxic heavy metal mainly originating from industrial activities and causes environmental pollution. To better understand its toxicity and pollution remediation, we must understand the effects of Cd on living beings. Saccharomyces cerevisiae (budding yeast) is an eukaryotic unicellular model organism. It has provided much scientific knowledge about cellular and molecular biology in addition to its economic benefits. Effects associated with copper and zinc, sulfur and selenium metabolism, calcium (Ca2+) balance/signaling, and structure of phospholipids as a result of exposure to cadmium have been evaluated. In yeast as a result of cadmium stress, "mitogen-activated protein kinase," "high osmolarity glycerol," and "cell wall integrity" pathways have been reported to activate different signaling pathways. In addition, abnormalities and changes in protein structure, ribosomes, cell cycle disruption, and reactive oxygen species (ROS) following cadmium cytotoxicity have also been detailed. Moreover, the key OLE1 gene that encodes for delta-9 FA desaturase in relation to cadmium toxicity has been discussed in more detail. Keeping all these studies in mind, an attempt has been made to evaluate published cellular and molecular toxicity data related to Cd stress, and specifically published on S. cerevisiae.

Biphasic activation of survival and death pathways in Arabidopsis thaliana cultured cells by sorbitol-induced hyperosmotic stress.

Hyperosmotic stresses represent some of the most serious abiotic factors that adversely affect plants growth, development and fitness. Despite their central role, the early cellular events that lead to plant adaptive responses remain largely unknown. In this study, using Arabidopsis thaliana cultured cells we analyzed early cellular responses to sorbitol-induced hyperosmotic stress. We observed biphasic and dual responses of A. thaliana cultured cells to sorbitol-induced hyperosmotic stress. A first set of events, namely singlet oxygen (1O2) production and cell hyperpolarization due to a decrease in anion channel activity could participate to signaling and osmotic adjustment allowing cell adaptation and survival. A second set of events, namely superoxide anion (O2-) production by RBOHD-NADPH-oxidases and SLAC1 anion channel activation could participate in programmed cell death (PCD) of a part of the cell population. This set of events raises the question of how a survival pathway and a death pathway could be induced by the same hyperosmotic condition and what could be the meaning of the induction of two different behaviors in response to hyperosmotic stress.

Contribution of salicylic acid glucosyltransferase, OsSGT1, to chemically induced disease resistance in rice plants.

Systemic acquired resistance (SAR), a natural disease response in plants, can be induced chemically. Salicylic acid (SA) acts as a key endogenous signaling molecule that mediates SAR in dicotyledonous plants. However, the role of SA in monocotyledonous plants has yet to be elucidated. In this study, the mode of action of the agrochemical protectant chemical probenazole was assessed by microarray-based determination of gene expression. Cloning and characterization of the most highly activated probenazole-responsive gene revealed that it encodes UDP-glucose:SA glucosyltransferase (OsSGT1), which catalyzes the conversion of free SA into SA O-beta-glucoside (SAG). We found that SAG accumulated in rice leaf tissue following treatment with probenazole or 2,6-dichloroisonicotinic acid. A putative OsSGT1 gene from the rice cultivar Akitakomachi was cloned and the gene product expressed in Escherichia coli was characterized, and the results suggested that probenazole-responsive OsSGT1 is involved in the production of SAG. Furthermore, RNAi-mediated silencing of the OsSGT1 gene significantly reduced the probenazole-dependent development of resistance against blast disease, further supporting the suggestion that OsSGT1 is a key mediator of development of chemically induced disease resistance. The OsSGT1 gene may contribute to the SA signaling mechanism by inducing up-regulation of SAG in rice plants.

A green Paramecium strain with abnormal growth of symbiotic algae.

Some hundred cells of Chlorella-like green algae are naturally enclosed within the cytoplasm of a single cell of green paramecia (Paramecium bursaria). Therefore, P. bursaria serves as an experimental model for studying the nature of endo-symbiosis made up through chemical communication between the symbiotic partners. For studying the mechanism of symbiotic regulations, the materials showing successful symbiosis are widely used. Apart from such successful model materials, some models for symbiotic distortion would be of great interest in order to understand the nature of successful symbiosis. Here, we describe a case of unsuccessful symbiosis causing unregulated growth of algae inside the hosting ciliates. Recently, we have screened some cell lines, from the mass of P. bursaria cells survived after paraquat treatment. The resultant cell lines (designated as KMZ series) show novel and unusual morphological features with heavily darker green colour distinguishable from the original pale green-coloured paramecia. In this type of isolates, endo-symbiotic algae are restricted within one or two dense spherical structures located at the center of the host cells' cytoplasm. Interestingly, this isolate maintains the host cells' circadian mating response which is known as an alga-dependent behaviour in the host cells. In contrast, we discuss that KMZ lacks the host-dependent regulation of algal growth, thus the algal complex often over-grows obviously exceeding the original size of the normal hosting ciliates. Additionally, possible use of this isolate as a novel model for symbiotic cell-to-cell communication is discussed.