The effect of cold priming on the fitness of Arabidopsis thaliana accessions under natural and controlled conditions

Priming improves an organism's performance upon a future stress. To test whether cold priming supports protection in spring and how it is affected by cold acclimation, we compared seven Arabidopsis accessions with different cold acclimation potentials in the field and in the greenhouse for growth, photosynthetic performance and reproductive fitness in March and May after a 14 day long cold-pretreatment at 4 °C. In the plants transferred to the field in May, the effect of the cold pretreatment on the seed yield correlated with the cold acclimation potential of the accessions. In the March transferred plants, the reproductive fitness was most supported by the cold pretreatment in the accessions with the weakest cold acclimation potential. The fitness effect was linked to long-term effects of the cold pretreatment on photosystem II activity stabilization and leaf blade expansion. The study demonstrated that cold priming stronger impacts on plant fitness than cold acclimation in spring in accessions with intermediate and low cold acclimation potential

Cold regulation of plastid ascorbate peroxidases serves as a priming hub controlling ROS signaling in Arabidopsis thaliana

Background Short cold periods comprise a challenge to plant growth and development. Series of cold stresses improve plant performance upon a future cold stress. This effect could be provoked by priming, training or acclimation dependent hardening. Here, we compared the effect of 24 h (short priming stimulus) and of 2 week long cold-pretreatment (long priming stimulus) on the response of Arabidopsis thaliana to a single 24 h cold stimulus (triggering) after a 5 day long lag-phase, to test Arabidopsis for cold primability. Results Three types of pretreatment dependent responses were observed: (1) The CBF-regulon controlled gene COR15A was stronger activated only after long-term cold pretreatment. (2) The non-chloroplast specific stress markers PAL1 and CHS were more induced by cold after long-term and slightly stronger expressed after short-term cold priming. (3) The chloroplast ROS signaling marker genes ZAT10 and BAP1 were less activated by the triggering stimulus in primed plants. The effects on ZAT10 and BAP1 were more pronounced in 24 h cold-primed plants than in 14 day long cold-primed ones demonstrating independence of priming from induction and persistence of primary cold acclimation responses. Transcript and protein abundance analysis and studies in specific knock-out lines linked the priming-specific regulation of ZAT10 and BAP1 induction to the priming-induced long-term regulation of stromal and thylakoid-bound ascorbate peroxidase (sAPX and tAPX) expression. Conclusion The plastid antioxidant system, especially, plastid ascorbate peroxidase regulation, transmits information on a previous cold stress over time without the requirement of establishing cold-acclimation. We hypothesize that the plastid antioxidant system serves as a priming hub and that priming-dependent regulation of chloroplast-to-nucleus ROS signaling is a strategy to prepare plants under unstable environmental conditions against unpredictable stresses by supporting extra-plastidic stress protection

Human Monocytes Exposed to SARS-CoV-2 Display Features of Innate Immune Memory Producing High Levels of CXCL10 upon Restimulation

Introduction: A role for innate immune memory in protection during COVID-19 infection or vaccination has been recently reported. However, no study so far has shown whether the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) can train innate immune cells. The aim of this study was to investigate whether this virus can induce trained immunity in human monocytes. Methods: Monocytes were exposed to inactivated SARS-CoV-2 (iSARS-CoV-2) for 24 h, followed by a resting period in the medium only and a secondary stimulation on day 6 after which the cytokine/chemokine and transcriptomic profiles were determined. Results: Compared to untrained cells, the iSARS-CoV-2-trained monocytes secreted significantly higher levels of IL-6, TNF-α, CXCL10, CXCL9, and CXCL11 upon restimulation. Transcriptome analysis of iSARS-CoV-2-trained monocytes revealed increased expression of several inflammatory genes. As epigenetic and metabolic modifications are hallmarks of trained immunity, we analyzed the expression of genes related to these processes. Findings indicate that indeed SARS-CoV-2-trained monocytes show changes in the expression of genes involved in metabolic pathways including the tricarboxylic acid cycle, amino acid metabolism, and the expression of several epigenetic regulator genes. Using epigenetic inhibitors that block histone methyl and acetyltransferases, we observed that the capacity of monocytes to be trained by iSARS-CoV-2 was abolished. Conclusion: Overall, our findings indicate that iSARS-CoV-2 can induce properties associated with trained immunity in human monocytes. These results contribute to the knowledge required for improving vaccination strategies to prevent infectious diseases

Die Rolle des plastidären antioxidativen Schutzsystems von Arabidopsis thaliana im Bezug auf das Gedächtnis an ausgedehnten Kältestress und dessen ökophysiologishe Konsequenzen

Survival and acclimation to different environmental changes are two main tasks during evolutional process in plants. Low temperature is a limiting growth factor and has great impact on metabolically processes. Slowing down biochemical reactions and making kinetic differences higher upon low temperature causes photostatic redox-imbalances. Due to these imbalances more reactive oxygen species (ROS) are generated. ROS and the chloroplasts as major sites of their production are important initiators and/or converters of retrograde signals to the nucleus under stress conditions. It is accepted that transient environmental stress experience can prepare an organism for improved defense responses when the next stress occurs. Memorizing the previous (priming) experience during the lag-phase prepares for future (triggering) stress responses. We suggest that the chloroplast antioxidant system behaves as a pro-active priming hub under cold stress. It was shown that the first stress stimulus is memorized and stored and this information can be recalled in response to a subsequent stress. Cold has an effect on the ascorbate signature and the H2O2 pattern was crucial for memory formation. Priming was shown to be conveyed via modulations in the stromal and thylakoid APx ratio as well as Cu-Zn superoxide dismutase, resulting in the alteration of the ROS signature in primed and triggered plants compared to only triggered plants. The low expression of marker genes for chloroplast ROS signaling (ZAT10 and BAP1) was accompanied by the activation of the pleiotropic stress marker genes (PAL1 and CHS) expression and contributed to the stronger extra-plastidic protection in primed plants. Cold tolerance-related primability among Arabidopsis accessions was observed via higher chloroplast antioxidant system regulation and weaker accumulation of extra-plastidic ROS-signaling molecules in cold tolerant accession Ms-0 with a short vegetation period. Growing faster, flowering earlier and producing high amount of seeds were some of the plants priming strategies in the unstable environment. The cold-priming effect on chloroplast-to-nucleus ROS signaling was specific to the type of triggering stress. Regulation of chloroplast-to-nucleus ROS signaling is a beneficial strategy when next stress period occurs by supporting protection outside of the plastid in the model plant species Arabidopsis thaliana.Akklimatisation und das Überleben von unterschiedlichsten Umweltbedingungen sind zwei der evolutionären Herausforderungen an Pflanzen. Niedrige Temperaturen limitieren das Wachstum und haben großen Einfluss auf metabolische Prozesse. Sie verlangsamen biologische Reaktionen und vergrößern kinetische Unterschiede zwischen Enzymen, was zu einer gestörten Redox-Balance führt. Durch diese Missverhältnisse können größere Mengen an reaktiven Sauerstoffspezies (ROS) entstehen. ROS und der Chloroplast als Hauptentstehungsort sind wichtige Initiatoren bzw. Umwandler von retrograden Signalen bei Stress. Es ist allgemein akzeptiert, dass vorübergehende Stresserfahrungen Organismen zu erhöhten Stressantworten während eines zweiten, späteren Stresses führen können. Die Erinnerung an vorherige (Priming-) Erfahrungen während einer Phase unter optimalen Bedingungen (lag- phase) ist notwendig um bei folgenden Stressantworten (Triggern) effizienter an die Bedingungen angepasst zu reagieren. Wir behaupten, dass das plastidäre antioxidative Schutzsystem als ein proaktiver Priming-Knotenpunkt während Kältestress wirkt. Es wurde gezeigt, dass die Information über den ersten Stress gespeichert wird und dass diese während eines Folgestresses verarbeitet wird. Kälte hat einen Effekt auf den Ascorbathaushalt und die Menge an H2O2. Dieser Effekt entscheidend über die Entstehung eines „Gedächtnisses―. Weiterhin wurde aufgedeckt, dass in geprimt und getriggertend Pflanzen über die Modulation des Verhältnisses von stromaler und thylakoidgebundener Ascorbatperoxidase und die Cu-Zn-Superoxiddismutase im Vergleich zu nur getriggerten Pflanzen die ROS-Signatur gezielt verändert wird. Die niedrige Expression von zwei plastidären ROS-Markergenen (ZAT10 und BAP1) ging einher mit der Aktivierung von pleiotropen Stressmarkergenen (PAL1 und CHS). Dies führte zu einem besseren Schutz in geprimten Pflanzen. Die Fähigkeit zum Kältepriming wurde exemplarisch in Akzessionen von Arabidopsis beobachtet. Eine stärkere Regulation des plastidären antioxidativen Schutzsystems und eine schwächere Akkumulation von extraplastidären ROS-Signalen wurde z.B. in Ms-0 gefunden. Diese Akzession hat nur eine kurze Vegetationszeit, wodurch sie gezwungen ist schneller zu wachsen, früher zu blühen und mehr Samen zu produzieren; all dies sind Anpassungen annicht-stabile Umweltbedingungen. Der Effekt des Kälteprimings auf Plastid zu Nukleus Signalen ist triggerspezifisch. Die Regulation der ROS-Signale von Chloroplasten zum Zellkern ist eine vorteilhafte Strategie in dem Modelorganismus Arabidopsis thaliana, indem sie die nicht-plastidäre Abwehr erhöht

Preparation of 9-hydroxynonanoic acid methyl ester by ozonolysis of vegetable oils and its polycondensation

Vegetable oil-based and potentially biodegradable polyesters were prepared from 9-hydroxynonanoic acid methyl ester. This paper describes ozonolysis of vegetable oils and the method for preparation of useful monomers and in particular 9-hydroxynonanoic acid methyl ester. Ozonolysis of soybean oil and castor oil in methanol and methylene chloride solution, followed by reduction with sodium borohydride was used to obtain a mixture of triols, diols and monols. Triglyceride triols were separated from the rest of the mixture and transesterified with methanol to obtain methyl esters of fatty acids and glycerin. The main component of fatty acids was 9-hydroxynonanoic acid methyl ester, which was characterized and used for polycondensation by transesterification. High molecular weight polyhydroxy alcanoate was a solid having a melting point of 75°C. The molecular weight of the resulting polyester was affected by the purity of the monomer and side reactions such as cyclization. The polymer was characterized by chromatographic, thermal and analytical methods

Implementing qualitative reasoning for structural design using constraint propagation

Rhodobryum ontariense (Kindb.) Kindb. (Bryaceae, Bryophyta) is a rare moss, only recently discovered in Serbia (at Deliblatska Sands). After a revision of the genus Rhodobryum in Serbia, it was concluded that all high-mountain records belong to R. roseum, while R. ontariense is confined to the one known locality at Deliblatska Sands. It is listed in the bryophyte red-list of Serbia and Montenegro. Within the single known locality we have counted 15 small sub-populations over a total surface area of 6 hectares. The species is always in sterile condition and has been recorded only on dunes exposed to the north, at the edge of shrub-grassland transition interspersed with fragments of steppe vegetation. No propagules are known. This raised the question of whether the population was once continuous, or whether vectors exist that spread detached plants or fragments to establish new subpopulations. To answer this question an isozyme analysis was performed to estimate the genetic structure of this isolated population. Based on the isozyme forms of superoxide dismutase and peroxidase at least six haplotypes were determined within the population. It can be concluded that the present patches of the moss do not derive from one subpopulation. Some kind of short-distance dispersal exists, but it remains unclear what structures act as propagules and what is the vector for them.Projekat ministarstva br. 143015; i br. 14303