Trehalose (α‐d‐glucopyranosyl‐1,1‐α‐d‐glucopyranoside), a non‐reducing disaccharide, has been found in a wide variety of organisms playing an important role as an abiotic stress protectant. Plants ...may come into contact with trehalose from exogenous sources, such as in plant–rhizobia symbiosis in which the rhizobia have the capacity to produce trehalose. The aim of this work is to analyse how trehalose and trehalase respond to salt stress in root nodules of legumes. For this purpose, tissue expression of Medicago truncatula trehalase gene (MTTRE1) and the expression of MTTRE1 under salt stress were analysed by real‐time quantitative reverse transcription‐PCR method. Trehalase activity was determined and trehalose was also measured by gas chromatography. In addition, trehalase protein occurrence in different organs and at different developmental stages in Phaseolus vulgaris plants has been studied. MTTRE1 expression is induced in nodules compared with leaves and roots, indicating a transcriptional regulation of trehalase in the presence of the microsymbiont. Under salt stress conditions, trehalase activity is downregulated at the transcriptional level, allowing trehalose accumulation. The results found in this study led us to conclude that trehalase activity is induced in root nodules of legumes by the microsymbiont and that under salt stress conditions; trehalase activity is downregulated at the transcriptional level in M. truncatula nodules. This allows trehalose accumulation and supports the possible role of this disaccharide as a stabilizer against salt stress conditions.
Nurses' perceptions of preceptorships for undergraduate nursing students are crucial for designing effective and tailor-made strategies to improve nurses' involvement, motivation, commitment, and ...satisfaction in preceptorships.
The aim of this study was to determine nurses' perceptions of preceptorships for nursing students in two hospitals located in northern Spain.
This study was conducted in two highly specialized, medium-large, university tertiary care hospitals, including one public and one private hospital, located in northern Spain.
The participants of this study were clinical nurses in private and public health centers who had been preceptors for at least one year.
A descriptive cross-sectional study was carried out between October 2021 and April 2022, with a total sample of 307. The validated “Involvement, Motivation, Satisfaction, Obstacles and Commitment” (IMSOC) questionnaire was used. Descriptive statistics and bivariate analysis were carried out. The variables included sex, age, educational level, preceptorship training, professional experience, work sector, work setting, and type of contract.
The mean global questionnaire score was 115.25 ± 33.86 (95 % CI: 111.62–123), with the highest score obtained for the “Involvement” dimension (29.96; SD: 9.23; 95 % CI: 29.01–34.87). Age showed statistically significant negative correlations with the overall and dimension scores (p < 0.05). Comparisons by work sector and type of contract reflected that nurses working in the private sector and those with permanent contracts had higher motivation and commitment scores.
Preceptors had positive perceptions of their role in undergraduate nursing students' education. Age, work sector, type of contract and time allocation should be considered when designing strategies to enhance the involvement, motivation, commitment, and satisfaction of nurses in their experiences as preceptors for undergraduate nursing students. Improving the preceptorship experience will benefit both nurses and students by improving preparation, satisfaction, and retention.
•The preceptorship process is highly valued by professionals in both primary care and hospital settings.•The level of satisfaction, motivation and involvement in the mentoring process is primarily influenced by elements of the clinical setting.•Developing educational and management strategies like work environment and the type of contract can improve the experience, engagement and satisfactin of professionals in clinical mentoring.
The strength of high‐frequency radio signals, when refracted by the ionosphere, can be strongly influenced by ionospheric absorption. Accurate modeling of the amount of this absorption is a vital ...part of many studies of radio waves propagating in the ionosphere. We have developed a new, flexible model of ionospheric absorption, the Semiempirical Model for Ionospheric Absorption based on the NRLMSISE‐00 atmospheric model (SiMIAN). This article describes the methods and formulae used by SiMIAN, a comparison of SiMIAN with an older absorption model, and validation work performed by simulating the power returned in vertical incidence soundings of the ionosphere and comparing the results with real soundings.
Key Points
We have developed a new model for ionospheric absorption, SiMIAN
Can model O and X modes as well as non‐typical propagation paths
Performed validation on SiMIAN using vertical incidence soundings
Polyamines (PAs) such as spermidine (Spd) and spermine (Spm) are small ubiquitous polycationic compounds that contribute to plant adaptation to salt stress. The positive effect of PAs has been ...associated to a cross-talk with other anti-stress hormones such as brassinosteroids (BRs). In this work we have studied the effects of exogenous Spd and Spm pre-treatments in the response to salt stress of the symbiotic interaction between Medicago truncatula and Sinorhizobium meliloti by analyzing parameters related to nitrogen fixation, oxidative damage and cross-talk with BRs in the response to salinity.
Exogenous PAs treatments incremented the foliar and nodular Spd and Spm content which correlated with an increment of the nodule biomass and nitrogenase activity. Exogenous Spm treatment partially prevented proline accumulation which suggests that this polyamine could replace the role of this amino acid in the salt stress response. Additionally, Spd and Spm pre-treatments reduced the levels of H2O2 and lipid peroxidation under salt stress. PAs induced the expression of genes involved in BRs biosynthesis which support a cross-talk between PAs and BRs in the salt stress response of M. truncatula-S. meliloti symbiosis.
In conclusion, exogenous PAs improved the response to salinity of the M. truncatula-S. meliloti symbiosis by reducing the oxidative damage induced under salt stress conditions. In addition, in this work we provide evidences of the cross-talk between PAs and BRs in the adaptive responses to salinity.
•Exogenous polyamines increment nodule biomass and nitrogenase activity in the symbiosis M. truncatula-S. meliloti.•Spermidine and spermine pre-treatments reduce the levels of H2O2 and lipid peroxidation under salt stress.•Polyamines induce the expression of genes involved in brassinosteroids biosynthesis.•Polyamines improve the response to salinity of M. truncatula-S. meliloti symbiosis by reducing the oxidative damage.
Background and purpose: : The pathophysiology of stroke-associated infection (SAI) is uncertain. The cytokine profile and peripheral white cell response were assessed in patients with or without SAI. ...Methods: The incidence of SAI was assessed in 110 patients with ischaemic stroke allocated antibiotic prophylaxis or placebo within 24 h of clinical onset. Peripheral white cell counts, interleukin (IL)6, tumour necrosis factor (TNF)α and IL10 were measured in plasma. Results: 17 (15%) patients developed infection and showed time-dependent increases of total white cell count, neutrophils, monocytes, lymphocytes, IL6 and IL10, whereas TNFα and the TNFα/IL10 ratio decreased. In logistic regression, IL10 (odds ratio (OR) 1.08, 95% confidence interval (CI) 1.01 to 1.16), monocyte count (OR 1.42, 95% CI 1.08 to 1.87) and National Institute for Health Stroke Survey score on admission (OR 1.17, 95% CI 1.05 to 1.31) were independent predictors of systemic infection. Conclusions: SAI is associated with stroke severity, excessive IL10-mediated response and an increased number of circulating monocytes. These results support the finding that acute ischaemic brain injury triggers a blood-borne anti-inflammatory response that decreases the antimicrobial drive of the immune system.
Legumes have the capacity to fix nitrogen in symbiosis with soil bacteria known as rhizobia by the formation of root nodules. However, nitrogen fixation is highly sensitive to soil salinity with a ...concomitant reduction of the plant yield and soil fertilization. Polycationic aliphatic amines known as polyamines (PAs) have been shown to be involved in the response to a variety of stresses in plants including soil salinity. Therefore, the generation of transgenic plants overexpressing genes involved in PA biosynthesis have been proposed as a promising tool to improve salt stress tolerance in plants. In this work we tested whether the modulation of PAs in transgenic Medicago truncatula plants was advantageous for the symbiotic interaction with Sinorhizobium meliloti under salt stress conditions, when compared to wild type plants. Consequently, we characterized the symbiotic response to salt stress of the homozygous M. truncatula plant line L-108, constitutively expressing the oat adc gene, coding for the PA biosynthetic enzyme arginine decarboxylase, involved in PAs biosynthesis. In a nodulation kinetic assay, nodule number incremented in L-108 plants under salt stress. In addition, these plants at vegetative stage showed higher nitrogenase and nodule biomass and, under salt stress, accumulated proline (Pro) and spermine (Spm) in nodules, while in wt plants, the accumulation of glutamic acid (Glu), γ-amino butyric acid (GABA) and 1-aminocyclopropane carboxylic acid (ACC) (the ethylene (ET) precursor) were the metabolites involved in the salt stress response. Therefore, overexpression of oat adc gene favours the symbiotic interaction between plants of M. truncatula L-108 and S. meliloti under salt stress and the accumulation of Pro and Spm, seems to be the molecules involved in salt stress tolerance.
An analysis is made of the socio-economic impact in a region in which a nuclear plant is decommissioned. The average age of nuclear power plants around the world is high, so that many are close to ...the end of their useful life. The issue of this impact will be important in a few years for various reasons, especially because those plants tend to be drivers of the economic activity in the areas in which they are located. The focus of this communication is on these socio-economic effects. Methodologically, socio-economic analysis uses a linear Social Accounting Matrix model that improves traditional Input-Output approaches by covering the induced effects generated from the receptors of income out to other sectors of the economy. The procedure is applied to an empirical analysis of the Almaraz Nuclear Power Plant in Spain. This was purposely chosen as sharing many of the general characteristics of nuclear plants around the world. If the plant is closed down, our results suggest that there will be a clear negative impact in terms of employment and added value generation.
In this experimental work, injection molding of alumina parts was performed with a developed binder system based on high density polyethylene (HDPE), paraffin wax (PW) and stearic acid. Firstly, the ...optimum binder composition was determined by torque measurements and rheology. Alumina feedstocks with powder loadings between 50 and 60% in volume were prepared with the developed binder system. A suitable formulation for powder injection molding was chosen based on torque measurements, rheological behaviour and homogeneity of feedstocks. All the feedstocks studied exhibited a pseudoplastic behaviour with flow behaviour index
n
<
1. Feedstock with 58
vol.% solid loading exhibited the most suitable behaviour for ceramic injection molding and was chosen to perform the complete process. Debinding cycle was designed based on thermogravimetrical analysis and differential scanning calorimetry. The best results were found using solvent debinding followed by thermal debinding. Final parts had densities close to 99% after sintering at 1600
°C during 2
h.
Background and purpose: Mucosal microcirculation is compromised during gastric damage induced by non‐steroidal anti‐inflammatory drugs, such as aspirin. Consequently, oxygen supply to epithelial ...cells is decreased. The trefoil factor (TFF) peptides are involved in mechanisms of defence and repair in the gastrointestinal tract but their regulation at sites of gastric injury is unknown.
Experimental approach: Hypoxia and expression of TFF genes and peptides were measured in the damaged stomach of aspirin‐treated rats. In a human gastric cell line (AGS cells), the effects of hypoxia and of hypoxia inducible factor (HIF)‐1 (through transient transfection of HIF‐1α siRNA or over‐expression of HIF‐1α) on TFF gene expression were evaluated.
Key results: Hypoxyprobe immunostaining, up‐regulation of TFF2 (1.9‐fold) and TFF3 (1.8‐fold) and a non‐significant increase of TFF1 (1.5‐fold) mRNA were observed in the damaged stomach of aspirin‐treated rats, compared with control animals. Hypoxia (3% O2, 16 h) induced mRNA for TFF1 (5.8‐fold), TTF2 (9.1‐fold) and TFF3 (9.3‐fold) in AGS cells, an effect mediated by HIF‐1, as transient transfection of HIF‐1α siRNA reduced the effects of hypoxia. Over‐expression of HIF‐1α by transfection in non‐hypoxic epithelial cells produced a similar pattern of TFF induction to that observed with hypoxia and transactivated a TFF1 reporter construct.
Conclusions and implications: Hypoxia inducible factor‐1 mediated the induction of TFF gene expression by hypoxia in gastric epithelial cells. Low oxygen levels and up‐regulation of TFF gene expression in the damaged stomach of aspirin‐treated rats suggest that hypoxia induced expression of TFF genes at sites of gastric injury.
Polyamines (PAs) are small nitrogen polycationic compounds involved in the response to salinity as well as in biotic interactions. Legumes are salt sensitive species characterised by their ability to ...establish symbiotic interactions with nitrogen fixing bacteria known as rhizobia that colonize the roots inducing the formation of nodules where the nitrogen fixation occurs. The content of PAs can be regulated among others by the catabolic enzymes diamine oxidase (DAO) and polyamine oxidase that additionally, are a source of H
2
O
2
, required in the regulation of biotic interactions including the rhizobia-legume symbiosis. Therefore, the role of PAs catabolism in the symbiosis between
Medicago truncatula
and
Sinorhizobium meliloti
under salt stress conditions was assessed in this work by the inhibition of DAO with the specific inhibitor aminoguanidine (AG). Treatment with AG limited the symbiosis, reducing root nodule formation and nitrogenase activity. Under salt stress conditions, the reduction of the PAs levels in nodules, together with glutamic acid (Glu), support that synthesis of PAs would be involved in the regulation of PAs levels rather than degradation. In addition, the content of H
2
O
2
in mature nodules and leaves is regulated by catalase activity (CAT), instead of PAs oxidation, while H
2
O
2
produced by PAs catabolism seems to be involved in the inhibition of the symbiosis establishment.
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