Synergistic effect of silicon availability and salinity on metal adsorption in a common estuarine diatom.

Increasing nitrogen and phosphorus discharge and decreasing sediment input have made silicon (Si) a limiting element for diatoms in estuaries. Disturbances in nutrient structure and salinity fluctuation can greatly affect metal uptake by estuarine diatoms. However, the combined effects of Si and salinity on metal accumulation in these diatoms have not been evaluated. In this study, we aimed to investigate how salinity and Si availability combine to influence the adsorption of metals by a widely distributed diatom Phaeodactylum tricornutum. Our data indicate that replete Si and low salinity in seawater can enhance cadmium and copper adsorption onto the diatom surface. At the single-cell level, surface potential was a dominant factor determining metal adsorption, while surface roughness also contributed to the higher metal loading capacity at lower salinities. Using a combination of non-invasive micro-test technology, atomic force microscopy, X-ray photoelectron spectroscopy, and Fourier transform infrared spectroscopy, we demonstrate that the diversity and abundance of the functional groups embedded in diatom cell walls vary with salinity and Si supply. This results in a change in the cell surface potential and transient metal influx. Our study provides novel mechanisms to explain the highly variable metal adsorption capacity of a model estuarine diatom.

Foliar-applied silicon and zinc nanoparticles improve plant growth, biochemical attributes, and essential oil profile of fennel (Foeniculum vulgare) under different irrigation regimes.

The comparative efficacy of silicon (Si) and zinc (Zn) nanoparticles (NPs) in mitigating drought stress in fennel (Foeniculum vulgare ) remains largely unexplored. This study evaluated the impact of Si NPs and Zn NPs on enhancing plant growth and physiological-biochemical attributes of fennel under varying irrigation regimes. The 2-year study was a split-pot design with irrigation at three irrigation levels (100, 75, and 50% field capacity, FC) and five treatments of foliar application of Si and Zn NPs (control, 1mM Si NP, 2mM Si NP, 1mM Zn NP, 2mM Zn NP). Results showed that drought stress reduced plant performance. Increases in superoxide dismutase (SOD, 131%) and catalase (CAT, 276%) were seen after a 50% FC drought without the use of Si and Zn NPs. Conversely, biological yield (34%), seed yield (44%), chlorophyll a +b (26%), relative water content (RWC, 21%), and essential oil (EO) yield (50%) were all reduced. However, application of Zn and Si, particularly 1mM Si and 2mM Zn, greatly mitigated drought stress via lowering CAT and SOD activity and enhancing plant yield, chlorophyll content, RWC, and EO. The composition of the EO consisted primarily of anethole, followed by limonene, fenchone, and estragole. During drought conditions, monoterpene hydrocarbons increased while oxygenated monoterpenes decreased. The opposite trend was observed for Si and Zn NPs. Our results suggest that applying Zn NPs at 2mM followed by Si NPs at 1mM improved plant resilience and EO yield in fennel plants under water stress.

Rich-silicon rice husk ash increases iron plaque formation and decreases cadmium and arsenic accumulation in rice seedlings.

Combined Cd (cadmium) and As (arsenic) pollution in cultivated land affects the safety of crops production and endangers human health. Rice (Oryza sativa L.) is a crop that uptakes Si (silicon), and Si can effectively promote rice growth and mitigate heavy metal toxicity. This study examined the effect and mechanism of Si-rich amendment (HA) prepared by aerobic combustion of rice husk on Cd and As accumulation in iron plaque and rice seedlings via hydroponic experiments. HA enhanced the vitality of rice growth because of its Si content and increased the amount of amorphous fraction iron plaques, furthermore, Cd content was decreased while the As was increased in both amorphous fraction and crystalline fraction iron plaques, resulting in the contents of Cd and As decreases by 10.0%-38.3% and 9.6%-42.8% for the shoots, and by 13.4%-45.2% and 9.9%-20.0% for the roots, respectively. In addition, X-ray diffraction and X-ray photoelectron spectroscopy illustrated significantly more Fe2O, MnO2 and MnO in the iron plaque after HA supply and the simultaneous existence of Mn-As and Mn-Si compounds. This result revealed less Cd from iron plaque and more As retention with HA supply, reducing the amount of Cd and As up taking and accumulation by rice seedlings. HA is beneficial to rice growth and reduce the absorption of heavy metals in plants. At the same time, HA is environmentally friendly, it can be used for the remediation of paddy fields contaminated by Cd and As.

Silicon-mediated resilience: Unveiling the protective role against combined cypermethrin and hymexazol phytotoxicity in tomato seedlings.

Insecticides and fungicides present potential threats to non-target crops, yet our comprehension of their combined phytotoxicity to plants is limited. Silicon (Si) has been acknowledged for its ability to induce crop tolerance to xenobiotic stresses. However, the specific role of Si in alleviating the cypermethrin (CYP) and hymexazol (HML) combined stress has not been thoroughly explored. This study aims to assess the effectiveness of Si in alleviating phytotoxic effects and elucidating the associated mechanisms of CYP and/or HML in tomato seedlings. The findings demonstrated that, compared to exposure to CYP or HML alone, the simultaneous exposure of CYP and HML significantly impeded seedling growth, resulting in more pronounced phytotoxic effects in tomato seedlings. Additionally, CYP and/or HML exposures diminished the content of photosynthetic pigments and induced oxidative stress in tomato seedlings. Pesticide exposure heightened the activity of both antioxidant and detoxification enzymes, increased proline and phenolic accumulation, and reduced thiols and ascorbate content in tomato seedlings. Applying Si (1 mM) to CYP- and/or HML-stressed seedlings alleviated pigment inhibition and oxidative damage by enhancing the activity of the pesticide metabolism system and secondary metabolism enzymes. Furthermore, Si stimulated the phenylpropanoid pathway by boosting phenylalanine ammonia-lyase activity, as confirmed by the increased total phenolic content. Interestingly, the application of Si enhanced the thiols profile, emphasizing its crucial role in pesticide detoxification in plants. In conclusion, these results suggest that externally applying Si significantly alleviates the physio-biochemical level in tomato seedlings exposed to a combination of pesticides, introducing innovative strategies for fostering a sustainable agroecosystem.

Preparation of Multistage Pore TS-1 with Enhanced Photocatalytic Activity, Including Process Studies and Artificial Neural Network Modeling for Synergy Assessment.

Antibiotic residues have been found in several aquatic ecosystems as a result of the widespread use of antibiotics in recent years, which poses a major risk to both human health and the environment. At present, photocatalytic degradation is the most effective and environmentally friendly method. Titanium silicon molecular sieve (TS-1) has been widely used as an industrial catalyst, but its photocatalytic application in wastewater treatment is limited due to its small pores and few active sites. In this paper, we report a method for preparing multistage porous TS-1 with a high specific surface area by alkali treatment. In the photocatalytic removal of CIP (ciprofloxacin) antibiotic wastewater experiments, the alkali-treated catalyst showed better performance in terms of interfacial charge transfer efficiency, which was 2.3 times higher than that of TS-1 synthesized by the conventional method, and it was found to maintain better catalytic performance in the actual water source. In addition, this research studied the effects of solution pH, contaminant concentration, and catalyst dosage on CIP degradation, while liquid chromatography-mass spectrometry (LC-MS) was used to identify intermediates in the degradation process and infer possible degradation pathways and the toxicity of CIP, and its degradation product was also analyzed using ECOSAR 2.2 software, and most of the intermediates were found to be nontoxic and nonharmful. Finally, a 3:5:1 artificial neural network model was established based on the experiments, and the relative importance of the influence of experimental conditions on the degradation rate was determined. The above results confirmed the feasibility and applicability of photocatalytic treatment of wastewater containing antibiotics using visible light excitation alkali post-treatment TS-1, which provided technical support and a theoretical basis for the photocatalytic treatment of wastewater containing antibiotics.

Silicon nanoparticles (SiNPs) mediate GABA, SOD and ASA-GSH cycle to improve cd stress tolerance in Solanum lycopersicum.

Contamination of agricultural products with Cadmium (Cd) is a global problem that should be considered for minimizing the risks to human health. Considering the potential effects of SiNPs in decreasing abiotic stress, a study was conducted to investigate the effect of SiNPs in the reduction of Cd stress on Solanum lycopersicum. SiNPs was used at 0, 25, 50 and 100 mg/l and CdCl2 at 0, 100 and 200 µM concentrations. The results showed that Cd stress caused a significant decrease in dry weight, content of GSH, ASA, significently increasing the activity of GR, APX, GST, SOD, as well as content of H2O2, MDA, proline, and GABA in shoots and roots compared to the control. SiNPs significantly increased shoot and root dry weight compared to the control. As a coenzyme, SiNPs induced the activity of antioxidant enzymes and significantly increased GST and GR gene expression compared to the control. SiNPs also caused a substantial increase in the content of ASA, GSH, proline and GABA compared to the control. By inducing the activity of antioxidant enzymes and metabolites of the ascorbate-glutathione (ASA-GSH) cycle, SiNPs removed a large content of H2O2 and significantly reduced the MDA content, and as a result led to the stability of cell membrane under Cd stress. Induction of ASA-GSH, GABA and SOD cycle by SiNPs clearly showed that SiNPs could be a potential tool to alleviate Cd stress in plants cultivated in areas contaminated with this heavy metal.

Silicon Modifies Photosynthesis Efficiency and hsp Gene Expression in European Beech (Fagus sylvatica) Seedlings Exposed to Drought Stress.

Background: Climate change is leading to severe and long-term droughts in European forest ecosystems. can have profound effects on various physiological processes, including photosynthesis, gene expression patterns, and nutrient uptake at the developmental stage of young trees. Objectives: Our study aimed to test the hypothesis that the application of silica (SiO2) influences photosynthetic efficiency and gene expression in 1- to 2-year-old Fagus sylvatica (L.) seedlings. Additionally, we aimed to assess whether silicon application positively influences the structural properties of leaves and roots. To determine whether the plant physiological responses are genotype-specific, seedlings of four geographically different provenances were subjected to a one-year evaluation under greenhouse conditions. Methods: We used the Kruskal-Wallis test followed by Wilcoxon's test to evaluate the differences in silicon content and ANOVA followed by Tukey's test to evaluate the physiological responses of seedlings depending on treatment and provenance. Results: Our results showed a significantly higher Si content in the roots compared with the leaves, regardless of provenance and treatment. The most significant differences in photosynthetic performance were found in trees exposed to Si treatment, but the physiological responses were generally nuanced and provenance-dependent. Expression of hsp70 and hsp90 was also increased in leaf tissues of all provenances. These results provide practical insights that Si can improve the overall health and resilience of beech seedlings in nursery and forest ecosystems, with possible differences in the beneficial role of silicon application arising from the large differences in wild populations of forest tree species.

[Occupational hazards of crystalline silicon solar cell manufacturing industry].

The wide use of crystalline silicon solar cells in the field of new energy is an important boost for China to achieve the environmental protection goal as soon as possible. However, the production and manufacturing processes of these cells give rise to various occupational hazards at workplace, thus posing health risks to workers. This review provided an overview of production processes of crystalline silicon solar cells, the characteristics of occupational health hazards (productive dust; physical factors, productive toxicant) and proposed occupational protection suggestions.

Si and Zn dual ions upregulate the osteogenic differentiation of mBMSCs: mRNA transcriptomic sequencing analysis.

Both silicon (Si) and zinc (Zn) ions are essential elements to bone health and their mechanisms for promoting osteogenesis have aroused the extensive attention of researchers. Thereinto, the mechanism by which dual ions promote osteogenic differentiation remains to be elucidated. Herein, the effects of Si and Zn ions on the cytological behaviors of mBMSCs were firstly studied. Then, the molecular mechanism of Si-Zn dual ions regulating the osteogenic differentiation of mBMSCs was investigated via transcriptome sequencing technology. In the single-ion system, Si ion at the concentration of 1.5 mM (Si-1.5) had better comprehensive effects of cell proliferation, ALP activity and osteogenesis-related gene expression levels (ALP, Runx2, OCN, Col-I and BSP); Zn ion at the concentration of 50 µM (Zn-50) demonstrated better combining effects of cell proliferation, ALP activity and same osteogenic genes expression levels. In the dual-ion system, the Si (1.5 mM)-Zn (50 µM) group (Si1.5-Zn50) synthetically enhanced ALP activity and osteogenesis genes compared with single-ion groups. Analysis of the transcriptome sequencing results showed that Si ion had a certain effect on promoting the osteogenic differentiation of mBMSCs; Zn ion had a stronger effect of contributing to a better osteogenic differentiation of mBMSCs than that of Si ion; the Si-Zn dual ions had a synergistic enhancement on conducting to the osteogenic differentiation of mBMSCs compared to single ion (Si or Zn). This study offers a blueprint for exploring the regulation mechanism of osteogenic differentiation by dual ions.

Characterization and function of promoters of silicon transporter genes PeLsi1-1 and PeLsi1-2 from moso bamboo (Phyllostachys edulis).

KEY MESSAGE: Promoters of moso bamboo silicon transporter genes PeLsi1-1 and PeLsi1-2 contain elements in response to hormone, silicon, and abiotic stresses, and can drive the expression of PeLsi1-1 and PeLsi1-2 in transgene Arabidopsis. Low silicon 1 (Lsi1) transporters from different species have been shown to play an important role in influxing silicon from soil. In previous study, we cloned PeLsi1-1 and PeLsi1-2 from Phyllostachys edulis and verified that PeLsi1-1 and PeLsi1-2 have silicon uptake ability. Furthermore, in this study, the promoters of PeLsi1-1(1910 bp) and PeLsi1-2(1922 bp) were cloned. Deletion analysis identified the key regions of the PeLsi1-1 and PeLsi1-2 promoters in response to hormone, silicon, and abiotic stresses. RT-qPCR analysis indicated that PeLsi1-1 and PeLsi1-2 were regulated by hormones, salt stress and osmotic stress. In addition, we found that the driving activity of the PeLsi1-1 and PeLsi1-2 promoters was regulated by 2 mM K2SiO3 and PeLsi1-1-P3 ~ P4 and PeLsi1-2-P4 ~ 5 were the regions regulated by silicon. Overexpression of PeLsi1-1 or PeLsi1-2 driven by 35S promoter in Arabidopsis resulted in a threefold increase of Si accumulation, whereas transgenic plants showed deleterious symptoms and dwarf seedlings and shorter roots under 2 mM Si treatment. When the 35S promoter was replaced by PeLsi1-1 or PeLsi1-2 promoter, a similar Si absorption was achieved and the transgene plants grew normally. This study, therefore, demonstrates that the promoters of PeLsi1-1 and PeLsi1-2 are indeed effective in driving the expression of moso bamboo Lsi1 genes and leading to silicon uptake.