Beneficial Elements Research Articles

The costs of curiosity and creativity: Minimizing the downsides while maximizing the upsides.

The unbridled positivity toward curiosity and creativity may be excessive. Both aid species survival through exploration and advancement. These beneficial effects are well documented. What remains is to understand their optimal levels and contexts for maximal achievement, health, and well-being. Every beneficial element to individuals and groups carries the potential for harm - curiosity and creativity included.

Agronomic and Genetic Strategies to Enhance Selenium Accumulation in Crops and Their Influence on Quality.

Selenium (Se) is an essential trace element that plays a crucial role in maintaining the health of humans, animals, and certain plants. It is extensively present throughout the Earth's crust and is absorbed by crops in the form of selenates and selenite, eventually entering the food chain. Se biofortification is an agricultural process that employs agronomic and genetic strategies. Its goal is to enhance the mechanisms of crop uptake and the accumulation of exogenous Se, resulting in the production of crops enriched with Se. This process ultimately contributes to promoting human health. Agronomic strategies in Se biofortification aim to enhance the availability of exogenous Se in crops. Concurrently, genetic strategies focus on improving a crop's capacity to uptake, transport, and accumulate Se. Early research primarily concentrated on optimizing Se biofortification methods, improving Se fertilizer efficiency, and enhancing Se content in crops. In recent years, there has been a growing realization that Se can effectively enhance crop growth and increase crop yield, thereby contributing to alleviating food shortages. Additionally, Se has been found to promote the accumulation of macro-nutrients, antioxidants, and beneficial mineral elements in crops. The supplementation of Se biofortified foods is gradually emerging as an effective approach for promoting human dietary health and alleviating hidden hunger. Therefore, in this paper, we provide a comprehensive summary of the Se biofortification conducted over the past decade, mainly focusing on Se accumulation in crops and its impact on crop quality. We discuss various Se biofortification strategies, with an emphasis on the impact of Se fertilizer strategies on crop Se accumulation and their underlying mechanisms. Furthermore, we highlight Se's role in enhancing crop quality and offer perspective on Se biofortification in crop improvement, guiding future mechanistic explorations and applications of Se biofortification.

Creativity as a Positive Factor in the Adolescence Stage: Relations with Academic Performance, Stress and Self-Esteem.

Creativity is a construct that aids in conflict resolution. Through the development of creative skills in adolescence, young people can carry out a series of strategies to make decisions or respond to a problem. The possession of creative skills helps students' personal wellbeing. The aim of this research is to analyze the relationships established between creativity and other individual variables such as academic performance, self-esteem and stress in adolescent students. The following descriptive cross-sectional study was carried out with a total sample of 743 adolescent students, between 14 and 19 years of age, from different educational centers in the province of Almería (Spain). The results obtained indicate a positive correlation between creativity and self-esteem and significant differences in the level of creativity among students who have repeated an academic year. Regression analyses indicate that both stress and creativity are two predictor variables of self-esteem. On the other hand, another of the findings obtained is that creativity acts as a mediating variable between self-esteem and repeating an academic year. It is discussed how creativity is a beneficial element in adolescence and, therefore, how its promotion can help the optimal development of adolescent students.

Impact of Organic Fertilization and some Beneficial Elements on the Performance and Storability of Salt-Stressed Crisphead Lettuce (Lactuca sativa L.)

Impact of Organic Fertilization and some Beneficial Elements on the Performance and Storability of Salt-Stressed Crisphead Lettuce (Lactuca sativa L.)

Early versus delayed mobilization after aneurysmal subarachnoid hemorrhage: a systematic review and meta-analysis of efficacy and safety.

A central tenet of Enhanced Recovery After Surgery (ERAS) is evidence-based medicine. Survivors of aneurysmal subarachnoid hemorrhage (aSAH) constitute a fragile patient population prone to prolonged hospitalization within neurointensive care units (NICUs), prolonged immobilization, and a range of nosocomial adverse events. Potentially, well-monitored early mobilization (EM) could constitute a beneficial element of ERAS protocols in this population. Therefore, the objective was to summarize the available evidence on EM strategies in patients with aSAH. The authors retrieved prospective and retrospective studies that reported efficacy or safety data on EM (defined as EM in the NICU starting ≤ 7 days after ictus) versus delayed mobilization (DM) (any strategy that comparatively delayed mobilization) after aSAH and were published after January 1, 2000, in PubMed/MEDLINE, Embase, and the Cochrane Library. Random-effects meta-analysis was performed. Ten studies analyzing 1292 patients were included for quantitative synthesis, including 1 randomized, 1 prospective nonrandomized, and 8 retrospective studies. Modified Rankin Scale scores at discharge were not different between the EM and DM groups (mean difference [MD] [95% CI] -0.86 [-2.93 to 1.20] points, p = 0.41). Hospital length of stay in days was markedly reduced in the EM group (MD [95% CI] -6.56 [-10.64 to -2.47] days, p = 0.002). Although there was a statistically significant reduction in radiological vasospasms (OR [95% CI] 0.65 [0.44-0.97], p = 0.03), the reduction in clinically relevant vasospasms was nonsignificant (OR [95% CI] 0.63 [0.31-1.26], p = 0.19). The odds of shunting were significantly lower in the EM group (OR [95% CI] 0.61 [0.39-0.95], p = 0.03). The rates of mortality, pneumonia, and thrombosis were similar among groups (p > 0.05). Due to a lack of high-quality studies, vastly varying protocols, and resulting statistical clinical and statistical heterogeneity, the level of evidence for recommendations regarding EM in patients with aSAH remains low. The currently available data indicated that mobilization within the first 5 days after aneurysm repair was feasible and safe without significant excessive adverse events, that neurological outcome with EM was almost certainly not worse than with prolonged immobilization, and that there was likely at least some reduction in length of hospital stay. Radiological and clinical vasospasms were not more frequent-with signals even trending toward a decrease-in patients who mobilized early. Higher-quality studies and implementation of full ERAS protocols are necessary to evaluate efficacy and safety with a higher level of evidence and to guide practical implementation through increased standardization. Clinical trial registration no.: CRD42023432828 (www.crd.york.ac.uk/prospero).

Historical shifting in grain mineral density of landmark rice and wheat cultivars released over the past 50 years in India

The ‘Green Revolution (GR)’ has been successful in meeting food sufficiency in India, but compromising its nutritional security. In a first, we report altered grain nutrients profile of modern-bred rice and wheat cultivars diminishing their mineral dietary significance to the Indian population. To substantiate, we evaluated grain nutrients profile of historical landmark high-yielding cultivars of rice and wheat released in succeeding decades since the GR and its impacts on mineral diet quality and human health, with a prediction for decades ahead. Analysis of grain nutrients profile shows a downward trend in concentrations of essential and beneficial elements, but an upward in toxic elements in past 50 y in both rice and wheat. For example, zinc (Zn) and iron (Fe) concentration in grains of rice decreased by ~ 33.0 (P < 0.001) and 27.0% (P < 0.0001); while for wheat it decreased by ~ 30.0 (P < 0.0001) and 19.0% (P < 0.0001) in past more than 50 y, respectively. A proposed mineral-diet quality index (M-DQI) significantly (P < 0.0001) decreased ~ 57.0 and 36.0% in the reported time span (1960–2010) in rice and wheat, respectively. The impoverished M-DQI could impose hostile effects on non-communicable diseases (NCDs) like iron-deficiency anemia, respiratory, cardiovascular, and musculoskeletal among the Indian population by 2040. Our research calls for an urgency of grain nutrients profiling before releasing a cultivar of staples like rice and wheat in the future.

Effect of Silicon on the Fruit Quality and Disease Response to Gummy Stem Blight in Cucumber

Gumm y stem blight (GSB) caused by Stagonosporopsis cucurbitacearum is the most destructive fungal disease affecting cucumber (Cucumis sativus L.) production. In Thailand, cucumber is one of the most popularly marketed vegetables and the cultivation of cucumbers or Cucurbitaceae often face impact epidemics and insect infestation. Furthermore, global climatic or climate change affects crop production too, which increases the frequency and severity of disease and pest outbreaks. Silicon (Si) enhances plant resistance against insect pests and fungal, bacterial, and viral diseases although Si is not the only beneficial element for plants but also it does play an important role in improving plant health and increasing resistance against pests and diseases. Therefore, the aim of the study was to investigate the effect of Si-application at two levels i.e., 50 ppm, and 100 ppm on yield, yield components, aroma, Si-concentration and disease response of cucumber under greenhouse condition in a randomized complete block design with 4 replications. Results, when compared with control, depicted that the highest fruit weight, marketable yield, fruit length, fruit width, and pith length were found under 50 ppm Si. Moreover, higher Si-levels resulted in increased aroma in rind (exocarp) and increased percentage of Si-concentrations in rind (exocarp), leaves, and shoot. Further in this research, the response of Gummy stem blight disease (GSB) in cucumber was also investigated the response of. The taxonomic identification of Stagonosporopsis cucurbitacearum was confirmed based on the evidence from morpho-molecular analyses and the pathogenicity test was performed to confirm its potential pathogenicity. The results showed that the varying treatments of Si affects the disease development. The 50 ppm Si caused the lowest disease response on cucumber fruits. This study can be used as a guideline for modifying Si-fertilizer application inputs to plants to increase disease resistance and fruit quality.

Quantitative ABCD Analysis of Ayurvedic Products and Their Impact on Trust

Purpose: The main goal of the paper is to pinpoint the variables affecting consumer trust in the use of Ayurvedic products. It seeks to assess the elements that influence the model's advantages, benefits, constraints and disadvantages. The goal is to use the ABCD model to give each aspect the appropriate scores or weights. To further shed light on the intricacies of the subject, the paper also intends to use factor analysis and elementary analysis. Design: This study conducted a thorough evaluation of the literature on the ABCD analytical framework. The study was successful in identifying key influencing factors and critical constituent characteristics that contribute to customer trust in consuming Ayurvedic products by quantitative analysis involving focus group interactions and suitable weightage assignment to essential attributes. Findings: The survey found that many companies and people are adopting a fresh strategy based on sustainability or survival in order to deal with their pressing problems and find quick relief. Focus group talks were used to analyse customer trust in the use of Ayurvedic products, and the ABCD analytic framework application was heavily endorsed for its beneficial elements. The results of this model thus support the effectiveness of using Ayurvedic products. Originality/value: The survey found that many companies and people are adopting a fresh strategy based on sustainability or survival in order to deal with their pressing problems and find quick relief. Focus group talks were used to analyse customer trust in the use of Ayurvedic products, and the ABCD analytic framework application was heavily endorsed for its beneficial elements. The results of this model thus support the effectiveness of using Ayurvedic products. Paper Type: Empirical Paper.

Uncovering the intricate relationship between plant nutrients and microplastics in agroecosystems

Recent scientific and media focus has increased on the impact of microplastics (MPs) on terrestrial and soil ecosystems. However, the interactions between MPs with macronutrients and micronutrients and their potential consequences for the agroecosystem are not well understood. Wheat (Triticum aestivum) is a staple food grown globally and has special importance for nations economies. Different elements can cause dangerous outcomes for wheat quality and production yield. In this study, batch adsorption experiments were done using 1 g of polyethylene tetra phthalate MP particles (PET-MPs) in varying concentrations of thirteen elements. The adsorption data were fitted by two common adsorption models (Langmuir and Freundlich). The effect of pH on the speciation of elements in aqueous solutions was investigated. The non-invasive characterization methods indicate the importance of O- and H-containing groups as the main component of selected MPs in controlling the adsorption of the elements ions. In the current study, adsorption and potential transport of the adsorbed macronutrients (K and Na) and micronutrients (Ni, Co, Cu, Al, Ba, Se, Fe, As, B, V and Ag) which include some beneficial (Na, Se, V), and non-essential or toxic elements (Al, As, Ag, Ba) onto MPs to the simulated roots of wheat were evaluated. The maximum sorption capacities of K+> Ni+2> Na+ > Co2+> Cu2+>Al+3 >Ba+2 >Se4+>Fe2+ >As5+ >B3+ >V5+> Ag + on PET-MPs at pH 5.8 and 25 ± 1 °C were 290.6 > 0.52> 0.51 > 0.20> 0.10 > 0.051> 0.024 > 0.003> 0.003 > 0.0015> 5.05 × 10−4> 1.7 × 10−4>3.7 × 10−6 mg g−1, respectively. The results highlight the importance of PET-MPs in controlling element adsorption in the rhizosphere. Our observations provide a good start for understanding the adsorption of multiple elements from the soil rhizosphere zone by PET-MPs.

Dissolution of Silicon from Soilless Substrates and Additives

Silicon (Si) is a beneficial element that is usually ample in mineral soil solution, but it is minimally bioavailable from soilless substrates. Several Si additives are commercially available, but the rate of dissolution of Si is not well-characterized. The ideal additive would steadily release bioavailable Si over the crop lifecycle. We report the long-term (120 days) dissolution of Si from soilless substrates and substrate additives. Studies involving gently agitated containers with deionized water indicated that perlite, sphagnum peat, vermiculite, and coconut coir released less than 0.03 mmol Si per liter of substrate per day. Rice hulls and wollastonite (CaSiO3) had 7- to 130-times faster rates of dissolution in this system; therefore, they were further studied in peat-based media. Dissolution of Si from the addition of 1 g wollastonite per liter of peat peaked at day 10 at 2.1 mmol Si per liter of media per leaching event (15% by volume); then, it gradually decreased over 120 days. The peak dissolution of Si amended with 12% rice hulls was similar, but it gradually increased over time. The concentrations of nine heavy metals in plant tissue were compared with untreated control plants to determine wollastonite and steel slag. The concentration of some elements statistically increased, but all concentrations were well below the legal concentration limits of these elements for human consumption in the United States. These results indicate that both wollastonite and rice hulls steadily release Si for up to 4 months; therefore, they are good sources of Si for container-grown crops in soilless media.

Effect of Different Levels of Organic and Phosphate Fertilizers on Yield and Quality of Three Sunflower Genotypes (Helianthus annus L.) in Northern Iraq

A field experiment was carried out in the semiarid region of Talkif district, which is 35 km north of city of Mosul within Nineveh Governorate, during two growing seasons 2019-2020 and 2020-2021 in sandy loom soil to study effect of three levels of organic manure (0, 400 and 800 kg.ha-1), a form of sheep manure, mixed thoroughly with the soil before planting, and three levels of phosphate fertilizers (0, 75, 150 kg ha-1 P2O5) added at once during soil preparation on yield and quality of three sunflower genotypes (Isera, Melabour and Velko). The experiment was carried out using a multifactorial randomized complete block design with three replicates for each experiment. Results indicate: effect of organic fertilizer was significant on all studied traits for both seasons. The treatment by adding organic fertilizer to soil with the amount of 800 kg.ha-1 gave the highest rate compared to addition of lowest ratio (400 kg.ha-1) and comparison treatment. Since Iraqi soil is poor in its content of phosphorus, which ranks second among the three most beneficial elements for plants, the addition of this element to soil at a rate of 150 kg.ha-1 led to a significant increase in all growth, yield and quality traits for both growing seasons. The genotypes of sunflower crop were significantly affected in all growth, yield and quality traits for both planting seasons. The Melabour genotype surpassed Velko and Isera genotypes in the studied traits for both growing seasons.

Efektivitas Reduksi Sampah Makanan dengan Perbedaan Bioaktivator Mengunakan Metode Open Windrow di Kota Surabaya

Food waste is a big problem in big cities, one of them is Surabaya. Indonesia is the second largest producer of food waste in the world. Many food scraps will be processed back into compost. This research was conducted to determine the effectiveness of using EM4 bioactivator, goat manure and deer manure in composting. The organic waste used is food waste, leftover leaves and compost starter. The composting method in this study used the open windrow method. Composting uses 6 open wind mounds with different levels of additional bioactivator. The results showed that the content of beneficial elements for plants, for levels of C/N ratio between 17.88 -19.65 in all composters. The content of the K value is between 0.39 – 0.48 and the content of the P value is between 0.40 – 0.48.

The Sequential Extraction of Municipal Solid Waste Incineration Bottom Ash: Heavy Metals Mobility and Sustainable Application of Ashes

This manuscript focuses on the sustainable utilization of municipal waste incineration ashes in construction, taking into account their substantial concentration of beneficial elements and the potential environmental pollution caused by the leaching of toxic elements due to naturally occurring processes. To assess heavy metal mobility in ashes, a sequential extraction method based on the European Community Bureau of Reference (BCR) was applied. It enables the determination of heavy metal fractions and provides valuable insights into their potential environmental impact and bioavailability. More than 80% of Cd, and Zn, and over 75% of Cu, exhibited strong associations with the most mobile exchangeable fraction, while over 60% of Al and Fe were predominantly bound to reducible. The distribution of As and Cr was relatively balanced between exchangeable and oxidizable fractions, whereas 100% of Pb was exclusively associated with oxidizable fractions, indicating immobilization of this element in the ash. The calculated Risk Assessment Codes and Individual Contamination Factors indicated a quite high to very high risk level for the element’s mobility and environmental contamination. For elements like Pb, Cd, Cu, and Zn, higher concentrations in the samples are associated with higher overall environmental risk. For elements like As and Cr, higher concentrations in the samples are associated with lower overall environmental risk. Studied ash exhibits potential as a resource, but equally it demands rigorous environmental management to ensure responsible utilization. The observed metal mobilization underscores the necessity for stringent containment and treatment measures to mitigate the risk of environmental contamination.

Comparison of Peat–Perlite-based and Peat–Biochar-based Substrates with Varying Rates of Calcium Silicate on Growth and Cannabinoid Production of Cannabis sativa ‘BaOx’

Growers have been searching for alternative horticultural growing media components because of their desire to use sustainable resources. Biochar is a carbon-based material that has been evaluated for use as an alternative aggregate in peat-based soilless substrates. Additionally, silicon (Si) has been examined as a beneficial element to promote plant growth and plant quality in a variety of crops. However, there has been limited research regarding the interaction of biochar as an aggregate and Si in soilless substrates. This study aimed to determine the impact of Si and biochar on plant growth and nutrient uptake for greenhouse-cultivated hemp (Cannabis sativa L.). Hemp plants were grown in one of 12 different substrate blends: with two rates of calcium silicate (CaSiO3), two aggregate types of biochar (medium or coarse) or perlite, and aggregate percentages of 85% peat + 15% aggregate and 70% peat + 30% aggregate. The cannabinoid concentration, plant height, diameter, or total plant biomass were similar across all substrate blends after 12 weeks of growth. Additionally, the use of CaSiO3 as a Si substrate amendment increased Si foliar concentrations, and the addition of biochar to peat-based mixes did not limit the Si availability for plant uptake. However, Si substrate amendments did not impact plant height, diameter, or total plant biomass. This suggests that the biochar tested during this study is suitable in peat-based substrates for C. sativa ‘BaOx’ production at rates up to 30% (by volume) in peat-based substrates with CaSiO3 amendments.

Effect of land use on carbon-, nitrogen- and silica soil stocks in the South African bushveld

Anthropogenic land use alters soil properties and influences biological transformations in the root zone, thereby affecting the distribution and supply of soil nutrients. It is generally acknowledged that human land-use activities such as intensive cattle farming and cultivation of citrus products lead to a homogenization of soil nutrients. This research aims at investigating the heterogeneity in soil nutrient stocks and BSi stocks (a beneficial plant element) within the Savannah biome of South Africa. In this study, C-N-Si stocks and their ratios were quantified in the soil of five different land use types, common in South Africa. The five different land use types are i) bush savannahs, ii) mopane-dominated woodlands, iii) annually burned land, iv) communal grazing land and v) citrus orchards. Empirical research however could not fully validate this hypothesis. In particular fire management and game farming (natural land use type) led to more variability in nutrient pools, with occasional occurrences of C-N-Si hotspots. Our results suggest that when ecosystem analysis of soil nutrient and carbon stocks is handled as a homogeneous unit potentially large mistakes are made, even in anthropogenic landscapes previously hypothesized with uniform nutrient distributions.

Physiological and metabolomic analyses reveal that Fe3O4 nanoparticles ameliorate cadmium and arsenic toxicity in Panax notoginseng

Heavy metal(loid)-contaminated available arable land seriously affects crop development and growth. Engineered nanomaterials have great potential in mitigating toxic metal(loid) stress in plants. However, there are few details of nanoparticles (NPs) involved in Panax notoginseng response to cadmium (Cd) and arsenic (As). Herein, integrating physiological and metabolomic analyses, we investigated the effects of Fe3O4 NPs on plant growth and Cd/As responses in P. notoginseng. Cd/As treatment caused severe growth inhibition. However, foliar application of Fe3O4 NPs increased beneficial elements in the roots and/or leaves, decreased Cd/As content by 10.38% and 20.41% in the roots, reduced membrane damage and regulated antioxidant enzyme activity, thereby alleviating Cd/As-induced growth inhibition, as indicated by increased shoot fresh weight (FW), the rootlet length and root FW by 40.14%, 15.74%, and 46.70% under Cd stress and promoted the shoot FW by 27.00% under As toxicity. Metabolomic analysis showed that 227 and 295 differentially accumulated metabolites (DAMs) were identified, and their accumulation patterns were classified into 8 and 6 clusters in the roots and leaves, respectively. Fe3O4 NPs altered metabolites significantly involved in key pathways, including amino sugar and nucleotide sugar metabolism, flavonoid biosynthesis and phenylalanine metabolism, thus mediating the trade-off between plant growth and defense under stress. Interestingly, Fe3O4 NPs recovered more Cd/As-induced DAMs to normal levels, further supporting that Fe3O4 NPs positively affected seedling growth under metal(loid)s stress. In addition, Fe3O4 NPs altered terpenoids when the seedlings were subjected to Cd/As stress, thus affecting their potential medicinal value. This study provides insights into using nanoparticles to improve potential active ingredients of medicinal plants in metal(loid)-contaminated areas.

288 Carers in transition: a support group for dementia carers whose spouse is transitioning to Long Term Care

Abstract Background In Ireland, an estimated 32% of people with dementia (PwD) are about to move to Long-Term Care (LTC). For spousal dementia carers, the transition to LTC is their greatest period of grief. Spousal dementia carers deal with changes in their relationship, identity, and role, when their spouse prepares to enter LTC. The Carers’ Transition Group (CTG) supports spousal carers in processing grief, educates about dementia and what to expect as their caring role evolves, signposts to resources, and supports improvement of overall well-being. The group is comprised of spousal carers of PwD who are currently patients of a Mental Health Service for Older Persons, transitioning to LTC. Methods Feedback on the Group was obtained via participant questionnaires and an assessment tool based on the Carer Support Needs Assessment Tool (CSNAT) administered pre-and-post, to ensure both the sessions and associated tools accurately reflected members identified needs. Results Group member feedback was very positive in regard to session content, group size and structure, and facilitator communication. Several participants expressed that simply hearing that others had experiences similar to their own as comforting. Conclusion The CTG highlights the need for research and development of psychosocial and psychoeducational interventions that provide support throughout the caring journey. Findings indicate an overall positive experience, with respondents expressing that sharing emotions and experiences, and feeling understood as the most beneficial element.

Silicon uptake and utilization on Panicum maximum grass modifies C:N:P stoichiometry under warming and soil water deficit

Future increases in air temperature are expected to increase the growth of Panicum maximum, but with climate change it will be common for the binomial increase in temperature and drought to occur. In this condition, plants may use strategies to adapt to this new scenario by favoring the uptake of beneficial elements such as Si and modifying plants nutritional status, but this needs to be tested. Thus, this research was conducted with the objective of evaluating the effect of warming and water restriction on Si uptake, accumulation, Si use efficiency, the C:Si, N:Si and P:Si stoichiometric ratios and their effects on growth of Panicum maximum plants grown under field conditions. The experiment was carried out in a 2 × 2 factorial scheme, with two temperature conditions (T): ambient temperature (aT), and high temperature (eT - increase of 2 °C above ambient temperature) combined with two levels of soil water availability (W), with water stress - non-irrigated (wS) and irrigated (sW), arranged in randomized blocks. Si concentration and accumulation are affected by temperature variations and soil water availability in different ways. Soil water restriction reduces leaf Si concentration, accumulation and increases the C, N and P stoichiometric ratios. Biomass production always improved for all growth cycles under warming and irrigated conditions, while, leaf C: Si, N: Si, and P: Si ratios decreased under non-irrigated and elevated temperature. It was revealed for the first time that the tolerance of Panicum maximum to warming and soil water restriction can be associated with Si uptake and changes in plant C:N:P stoichiometry.

AI-2 quorum sensing controlled delivery of cytolysin-A by tryptophan auxotrophic low-endotoxic Salmonella and its anticancer effects in CT26 mice with colon cancer

IntroductionThe limitations of conventional cancer therapies necessitate target-oriented, highly invasive, and safe treatment approaches. Hence, the intrinsic anti-tumor activity of Salmonella can offer better options to combat cancers. ObjectivesThis study aims to utilize attenuated Salmonella and deliver cytolytic protein cytolysin A (ClyA) under quorum sensing (QS) signaling for precise localized expression in tumors but not in healthy organs. MethodsThe therapeutic delivery strain was imposed with tryptophan auxotroph for selective colonization in tumors by trpA and trpE deletion, and lipid-A and O-antigen were altered by pagL and rfaL deletions using lambda red recombination method. The strain was transformed with the designed QS-controlled ClyA expression vector which was validated by western blot. The in vivo passaged therapeutic strain was used for treatment four times at a weekly interval, with a dose of 5 × 106 CFU/mouse for cancer therapy. ResultsThe attenuated strain induced minimal endotoxicity-related cytokines TNF-α, IL-1β, and IFN-γ and exhibited adequate colonization despite earlier exposure in mice. The QS-controlled ClyA expression was confirmed by western blot from bacterial cultures grown at different cell densities. The results demonstrated that the in vivo passaged strain preferentially colonized the tumor after vacating the spleen, liver, and lung, leaving no outward histological scars. The anti-cancer effect of the designed construct was evaluated in the murine CT26 colon cancer model. The expression of ClyA increased tumoricidal activity by 67 % compared to vector control. ConclusionHence, the anti-tumor effect of the engineered Salmonella strain was improved by ClyA expression via QS activation after achieving the threshold bacterial cell density. Further, immunohistochemical staining of the tumor and other organs corroborated the QS-controlled tumor-specific expression of ClyA. Overall, the results imply that the developed anti-cancer Salmonella has low endotoxicity and QS-controlled expression of ClyA as beneficial safety elements and supports recurrent Salmonella inoculation by O-antigen deficiency.

Silicon-phosphorus pathway mitigates heavy metal stress by buffering rhizosphere acidification

Heavy metal pollution threatens food security, and rhizosphere acidification will increase the bioavailability of heavy metals. As a beneficial element in plants, silicon can relieve heavy metal stress. However, less attention has been paid to its effects on plant rhizosphere processes. Here, we show that for Japonica (Nipponbare and Oochikara) and Indica (Jinzao 47) rice cultivars, the degree of root acidification was significantly reduced after silicon uptake, and the total organic carbon, citric acid, and malic acid concentrations in rice root exudates were significantly reduced. We further confirmed the results by q-PCR that the expressions of proton pump and organic acid secretion genes were down-regulated by 35–61 % after silicon treatment. Intriguingly, phosphorus allocation, an intensively studied mechanism of rhizosphere acidification, was altered by silicon treatment. Specifically, among total phosphorus in rice seedlings, the soluble proportion increased from 52.0 % to 61.7 %, while cell wall phosphorus decreased from 48.0 % to 32.3 %. Additionally, silicon-mediated alleviation of rhizosphere acidification has positive effects on relieving heavy metal stress. Simulation revealed that low acidification of the nutrient solution resulted in a decrease in bioavailable heavy metal concentrations, thereby reducing rice uptake. We further confirmed that the impediment of rhizosphere acidification led to free-state Cr3+ in solutions decreasing by 43 % and contributed up to 63 % of silicon's mitigation of Cr(III) stress. Overall, we propose a novel mechanism in which silicon reduces heavy metal absorption by increasing plant soluble phosphorus concentration and buffering rhizosphere acidification. This paper provides a unique insight into the role of silicon in plants and, more importantly, a theoretical reference for the rational application of silicon fertilizer to improve phosphorus utilization efficiency, alleviate heavy metal stress, and balance soil pH.