Unveiling the significance of foliar-applied silicon, selenium and phosphorus for the management and remediation of arsenic in two different rice genotypes.

Under paddy soil conditions, rice plants are vulnerable to arsenic (As) accumulation, thus causing potential threat to human health. Here we investigated the influence of foliar-applied phosphorus (P: 10 and 20 mg L-1), silicon (Si: 0.6 and 1.5 g L-1) and selenium (Se: 5 and 10 mg L-1) on As accumulation, morphological and physiological attributes of two contrasting rice genotypes (KSK-133 and Super Basmati) under As stress (25 mg kg-1 as arsenate). Silicon foliar dressing significantly (p < 0.05) reduced grain As uptake (up to 67%) and improved rice growth and chlorophyll content (28-66%) in both rice genotypes over their controls. Phosphorus foliar application resulted in a notable decrease (17%) in grain As uptake of coarse rice genotype (KSK-133), while it slightly increased grain As uptake in the fine one (Super Basmati; 6%) compared to controls. However, foliar-applied Se did not show significant effects on rice plants growth attributes and As uptake in both genotypes. Similarly, biochemical and enzymatic attributes (i.e., lipid peroxidation, electrolyte leakage, peroxidase and catalase) were improved with Si application in rice plants, except for P treatment that was only effective for coarse one. Foliar-applied Si also resulted in reduced cancer risk and hazard quotient (< 0.10) for both rice genotypes. This study advances our understanding on critical role of different foliar-applied nutrients and rice genotypes, which is imperative to develop effective As remediation and management strategies in coarse and fine rice genotypes and protect human health.

This study provided new insights on the significance of foliar-applied phosphorus, silicon and selenium for the management and remediation of arsenic in fine (Super Basmati) and coarse (KSK-133) rice genotypes. Foliar-applied silicon was the most promising strategy to mitigate arsenic uptake and minimizing health risk in rice grain of both genotypes, while phosphorus was effective only for coarse one, thus showing a genotype dependent response. Interestingly, selenium foliar application had no significant effect on arsenic accumulation in both rice genotypes.

Morphea after Silicone Implants.

Dear Editor, Silicone is a hydrophobic polymer containing silicon. Silicon is an essential compound of soft tissue proteoglycans. Reports about morphea and other autoimmune connective tissue disorders in association with silicone implants have stimulated the discussion of a possible link between the two, such as immunological cross-reactivity of silicone and connective tissue components (1). A number of case reports suggested a possible link to adjuvant autoimmune syndrome (2), morphea of the breast (3-5), and systemic scleroderma (6-8), among others. One study measured tissue silicon levels in women with silicone breast implants with and without symptoms or signs and compared these data with women who had either a saline breast implant or no augmentation at all. The authors detected higher levels of silicon in capsular tissue of patients with silicone implants, independent of the presence of any symptoms or signs (9,10). The conclusion was that there is no evidence of an association between silicone implants and autoimmune connective tissue disorders. Three other clinical trials investigating the role of silicone implants and induction of autoimmune connective tissue disorders also failed to find an association between the two (11-13). We report the case of a 32-year-old female patient who developed morphea of the breasts after silicone implants for augmentation after risk-reducing mastectomy for Cowden syndrome. She presented with pronounced capsule fibrosis of the implants. With a delay of several years, an ill-defined slightly hyperpigmented area developed on the breasts and ventral chest (Figure 1). The lesion was analyzed by dermoscopy (Figure 2), which found mild erythema, reduced vessels, and white areas (ill-defined dull white globules, fibrotic beams). A skin biopsy was taken. Histopathological analysis showed a normal epidermal layer, minor papillary edema, and some vascular ectasias in the papillary dermis and upper corium (Figure 3). There was mild perivascular inflammatory infiltrate of the deep dermal vascular plexus, composed of lymphocytes and monocytes with some plasma cells (Figure 4). Elastic fibers seemed unaffected (Figure 5). The diagnosis of an early morphea of the edematous-inflammatory stage was established. Treatment with topical corticosteroids and UVB-311 nm irradiation was recommended. Morphea of the breasts is an uncommon disorder. It may occur after radiotherapy of breast cancer, after silicone augmentation, or without any known cause (14-16). A meta-analysis found an increased risk for morphea/scleroderma, with a relative risk between 1.30 to 2.13 and an odds ratio for case control studies of 1.68 (17). The US FDA Breast Implant Approval Study evaluated almost 100,000 female patients with breast implants. An increased risk of Sjögren's syndrome, scleroderma, and rheumatoid arthritis was reported (18). We could not find any reference of an association between capsular fibrosis and morphea of the breast, although both represent fibrotic disorders. In conclusion, it seems possible that there is a link between morphea of the breast and chest as described herein and silicone breast implants, which is supported by epidemiological studies. However, a direct causal relationship is hard to demonstrate with a single case.

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.

Enzyme Activities in Reduction of Heavy Metal Pollution from Alice Landfill Site in Eastern Cape, South Africa.

Heavy metals are unbreakable, and most of them are poisonous to animals and people. Metals are particularly concerning among environmental contaminants since they are less apparent, have extensive effects on ecosystems, are poisonous, and bioaccumulate in ecosystems, biological tissues, and organs. Therefore, there is a need to use biological agents and phytoremediation processes such as enzymes because they have a high potential for effectively transforming and detoxifying polluting substances. They can convert pollutants at a detectable rate and are potentially suitable for restoring polluted environments. We investigated heavy metal concentrations in different soil samples collected in four sections in Alice and determined the enzyme activity levels present in the soil. The Pearson correlation analysis was conducted to check whether there was any relationship between heavy metal concentrations and enzyme activities in the soil. Samples were randomly collected in three weeks, and the microwave digestion method was used for sample treatment and preparation. Quantitation was achieved by inductively coupled plasma mass spectrometry (ICP-MS). The enzyme assay through incubation method was implemented for discovering the four selected enzymes (urease, invertase, catalase, and phosphatase), and their activity levels were examined colorimetrically by colorimetry spectrophotometer. The ICP-MS results revealed 16 predominating elements, namely: Al, Ba, Ca, Co, Cr, Cu, Fe, K, Mg, Mn, Na, Ni, Sr, and Zn, and the presence of a non-mental, which is phosphorus (P), and a metalloid in the form of silicon (Si) in all soil samples. Significant differences in metal concentrations were observed among the collection sites. The Al, Fe, K, Mg, and Ca concentrations were above WHO's permissible limits. While Ba, Mn, Na, and P were in moderate concentration, Cu, Cr, Co, Zn, Sr, and Ni were in small amounts recorded mostly below the permissible values from WHO. Four soil enzyme activities were determined successfully (urease, invertase, phosphatase, and catalase). A negative non-significant correlation existed between urease, invertase, phosphatase enzyme activity, and the concentration levels of all selected metals (Al, Ba, Ca, Co, Cu, Fe, K, Mg, Mn, Na, Ni, Cr, Sr, and Zn. In contrast, the content of catalase activity was associated non-significantly but positively with the range of selected heavy metals. This study suggests proper monitoring of residences' areas, which can provide detailed information on the impact of high heavy metal content on people's health. They are easily dispersed and can accumulate in large quantities in the soil. The necessary implementation of waste management programs will help the municipality adopt a strategy that will promote recycling programs and protect the residence health from this threat.

Proximate analysis, HPTLC finger print analysis and multi spectrometric analysis of Strychnos nux-vomica nuts.

OBJECTIVES: In alternative medicine, plants pay a major role. Some plants are known for their poisonous nature but still have some importance in the herbal drug industry for their medicinal value. Strychnos nux-vomica is one such plant. Its nuts are called as poison nut due to the presence of alkaloids. Both the nut and its minerals are having medicinal properties and hence the present study was indented to understand the nature of primary metabolites and multi elemental composition. METHODS: The nuts of S. nux-vomica were procured, authenticated, powdered and subjected to proximate analysis parameters, visualization of thin layer chromatographic separation (TLC) and finger print profiling through high performance thin layer chromatographic (HPTLC); surface morphology by scanning electron microscopy, energy dispersive X-ray analysis, X-ray fluorescence spectrometry, X-ray photoelectron spectrometry, powder X-ray diffractometry and inductively coupled plasma optical emission spectrometry. RESULTS: In HPTLC, 7 spots each under 254 nm, 366 nm, derivatization with vanillin sulphuric acid (VSR) reagent appeared and 2 spots with Dragendorff's reagent. In HPTLC, 12 peaks at 254 nm, 9 peaks at 366 nm, 7 peaks at 520 nm after derivatization with VSR reagent detected. Elements such as potassium, calcium, magnesium, chlorine, aluminium, iron, manganese, sodium, nickel, phosphorus, copper, zinc, sulphur and silicon were identified. PXRD revealed that the presence of potassium chloride, calcite and dolomite as major elemental composition. CONCLUSIONS: The presence of all the above elements has vital roles on human physiology. Potassium, calcium, chlorine, aluminium, nickel, phosphorus, sulphur and silicon are reported for the first time in this study.

Experimental study on the effect of Si and P ion content in SiO2 exposure environment on the degree of pulmonary fibrosis.

BACKGROUND: Silicosis is a public health issue in developing countries for long and cannot be completely cured. OBJECTIVE: To study the changes of ion content with TNF-α and TGF-ß expression in alveolar lavage fluid (BALF) at different time points in rats exposed to silica and to investigate their correlation with pulmonary fibrosis. METHODS: 42 rats were randomly divided into control group (n = 12) and exposure group (n = 30). Tissues of right lower lungs were collected and fixed for further Hematoxylin-eosin (HE) and Masson staining. We collected the BALF to examine the inflammatory cytokines of TNF-α and TGF-ß and measured the ion contents in BALF. RESULTS: The increase of TNF-α level was earlier than TGF-ß. The content of silica in BALF was significantly increased after exposure and reached the maximum at 7th day, similar to the curve of cytokine TGF-ß level. However, phosphorus ions increased quickly after gradual decline of silicon ion and roughly proportional to the curve of degree of fibrosis. CONCLUSIONS: Crystalline silica exposure can cause changes in TGF-ß and TNF-α in BALF and accompanied with fibrosis and ions content variation. The abnormal expression of phosphorus ion may have significance in the occurrence and development of silicosis.

Sol-Gel Synthesis, in vitro Behavior, and Human Bone Marrow-Derived Mesenchymal Stem Cell Differentiation and Proliferation of Bioactive Glass 58S.

Background: Bioactive glasses 58S, are silicate-based materials containing calcium and phosphate, which dissolved in body fluid and bond to the bone tissue. This type of bioactive glass is highly biocompatible and has a wide range of clinical applications. Methods: The 58S glass powders were synthesized via sol-gel methods, using tetraethyl orthosilicate, triethyl phosphate, and calcium nitrate, as precursors. Upon the analyses of phase and chemical structures of bioactive glass in different gelation times (12, 48, and 100 h), the appropriate heat treatment (at 525, 575, and 625 °C) was performed to eliminate nitrate compounds and stabilize the glass powder samples. The in vitro assay in SBF solution revealed the bioactivity of the synthesized 58S glass through the morphological (SEM), chemical structure (FTIR), release of calcium, phosphorous and silicon elements, pH variations, and weight loss measurements. The behavior of MSCs in the presence of bioactive glass powders was studied by MTT cytotoxicity, cell staining, ALP activity and biomineralization tests, as well as by the evaluation of ALP, osteocalcin, osteonectin, collagen I, and RUNX2 gene expression. Results: The results confirmed a gelation time of 100 h and a calcination temperature of 575 °C at optimal conditions for the synthesis of nitrate-free bioactive glass powders. Conclusion: The glass spherical nanoparticles in the range of 20-30 nm possess the improved bioactivity and osteogenic properties as demanded for bone tissue engineering.

Precise size separation of water-soluble red-to-near-infrared-luminescent silicon quantum dots by gel electrophoresis.

Gel electrophoresis, which is a standard method for separation and analysis of macromolecules such as DNA, RNA and proteins, is applied for the first time to silicon (Si) quantum dots (QDs) for size separation. In the Si QDs studied, boron (B) and phosphorus (P) are simultaneously doped. Codoping induces a negative potential on the surface of a Si QD and makes it dispersible in water. Si QDs with different B and P concentrations and grown at different temperatures (950 °C-1200 °C) are studied. It is shown that native polyacrylamide gel electrophoresis can separate codoped Si QDs by size. The capability of gel electrophoresis to immobilize size-separated QDs in a solid matrix makes detailed analyses of size-purified Si QDs possible. For example, the photoluminescence (PL) studies of the dried gel of Si QDs grown at 1100 °C demonstrate that a PL spectrum of a Si QD solution with the PL maximum around 1.4 eV can be separated into more than 15 spectra with the PL maximum changing from 1.2 to 1.8 eV depending on the migration distance. It is found that the relationship between the PL peak energy and the migration distance depends on the growth temperature of Si QDs as well as the B and P concentration. For all the samples with different impurity concentrations and grown at different temperatures, a clear trend is observed in the relationship between the full width at half maximum (FWHM) and the peak energy of the PL spectra in a wide energy range. The FWHM increases with the increasing peak energy and it is nearly twice larger than those observed for undoped Si QDs. The large PL FWHM of codoped Si QDs suggests that excitons are further localized in codoped Si QDs due to the existence of charged impurities.

Environmental characteristics in three seamount areas of the Tropical Western Pacific Ocean: Focusing on nutrients.

Nutrients distribution and influencing factors in three seamount areas named Y3, M2 and C4 of the Tropical Western Pacific Ocean (TWPO) were investigated. Nutrients showed obvious uplifts around the three seamounts, consistent with the uplifts of isotherms and isohalines, indicating the existence of a bottom-up process of nutrients. Meanwhile, compared with the stations away from seamount and the reference stations in the TWPO, nutrients concentrations around seamount were much higher. Among the three seamounts, the average nutrients concentrations were highest in Y3, while they were lowest in C4. Moreover, compared with the obvious nitrogen limitation in Y3 and M2, the N:P (13.5:1) and Si:N (6.1:1) were closed to the Redfield ratio. The current-seamount interaction was the determining influencing factor on nutrients distribution, causing the hydrology dynamic changes such as uplifts and Taylor column. Meanwhile, T and S also affected nutrients distribution, especially nutrients and T showed significant negative correlations.

In situ surface modification on dental composite resin using 2-methacryloyloxyethyl phosphorylcholine polymer for controlling plaque formation.

Composite resins (CRs) are widely used as dental restorative materials for caries treatment. They cause problems of secondary caries since Streptococcus mutans stays in the dental plaque, which the surface exists and produces acidic compounds during metabolism. The dental plaque depositions are induced by the protein adsorption on the surface. Therefore, suppression of protein adsorption on the surface of the CRs is important for inhibiting the formation of plaque and secondary caries. In this study we developed a surface treatment to provide an antibiofouling nature to the CRs by chemical reaction with 2-methacryloyloxyethyl phosphorylcholine (MPC) polymers in the oral cavity during dental treatment. To carry out the photochemical reaction on the remaining polymerizable groups of CRs, we synthesized the MPC polymer with a polymerizable group in the side chain. The MPC polymer could bind on the surfaces of the CRs chemically under dental treatment procedures. The treated surface showed significant resistance to oral protein adsorption and bacterial adhesion even when the surface was brushed with a toothbrush. Thus, we concluded that the photochemical reaction of the MPC polymer with the CRs in the oral cavity was good for making an antibiofouling surface and preventing secondary caries.

Genotypic Variation in Nickel Accumulation and Translocation and Its Relationships with Silicon, Phosphorus, Iron, and Manganese among 72 Major Rice Cultivars from Jiangsu Province, China.

Nickel (Ni) is a ubiquitous environmental toxicant and carcinogen, and rice is a major dietary source of Ni for the Chinese population. Recently, strategies to decrease Ni accumulation in rice have received considerable attention. This study investigated the variation in Ni accumulation and translocation, and also multi-element (silicon (Si), phosphorus (P), iron (Fe), and manganese (Mn)) uptake and transport among 72 rice cultivars from Jiangsu Province, China, that were grown under hydroponic conditions. Our results showed a 2.2-, 4.2-, and 5.3-fold variation in shoot Ni concentrations, root Ni concentrations, and translocation factors (TFs) among cultivars, respectively. This suggests that Ni accumulation and translocation are significantly influenced by the genotypes of the different rice cultivars. Redundancy analysis of the 72 cultivars revealed that the uptake and transport of Ni were more similar to those of Si and Fe than to those of P and Mn. The Ni TFs of high-Ni cultivars were significantly greater than those of low-Ni cultivars (p < 0.001). However, there were no significant differences in root Ni concentrations of low-Ni and high-Ni cultivars, suggesting that high-Ni cultivars could translocate Ni to shoots more effectively than low-Ni cultivars. In addition, the cultivars HD8 and YD8 exhibited significantly lower levels of Ni accumulation than their parents (p < 0.05). Our results suggest that breeding can be an effective strategy for mitigating excessive Ni accumulation in rice grown in Ni-contaminated environments.

Increased Aluminum Content in Certain Brain Structures is Correlated with Higher Silicon Concentration in Alcoholic Use Disorder.

INTRODUCTION: Alcohol overuse may be related to increased aluminum (Al) exposure, the brain accumulation of which contributes to dementia. However, some reports indicate that silicon (Si) may have a protective role over Al-induced toxicity. Still, no study has ever explored the brain content of Al and Si in alcoholic use disorder (AUD). MATERIALS AND METHODS: To fill this gap, the present study employed inductively coupled plasma optical emission spectrometry to investigate levels of Al and Si in 10 brain regions and in the liver of AUD patients (n = 31) and control (n = 32) post-mortem. RESULTS: Al content was detected only in AUD patients at mean ± SD total brain content of 1.59 ± 1.19 mg/kg, with the highest levels in the thalamus (4.05 ± 12.7 mg/kg, FTH), inferior longitudinal fasciculus (3.48 ± 9.67 mg/kg, ILF), insula (2.41 ± 4.10 mg/kg) and superior longitudinal fasciculus (1.08 ± 2.30 mg/kg). Si content displayed no difference between AUD and control, except for FTH. Positive inter-region correlations between the content of both elements were identified in the cingulate cortex, hippocampus, and ILF. CONCLUSIONS: The findings of this study suggest that AUD patients may potentially be prone to Al-induced neurodegeneration in their brain-although this hypothesis requires further exploration.

Green and non-leaching anti-bacterial and cytocompatible coating with build-in quaternary ammonium salt derived from methoxysilane functionalized soybean oil.

Preparation and evaluation of non-leaching antimicrobial polymeric coatings, derived from soybean oil, against bacterial contamination of some metallic biomedical devices are described in this work. Cyclic carbonate derivative of soybean oil (CSBO) was subjected to the reaction with 3-aminopropyl trimethoxysilane to produce a methoxysilane functional soybean oil (Si-SBU) with urethane linkage. A quaternary ammonium salt containing fatty amide molecule with reactive siloxane moiety (Si-SBQ) was also synthesized from soybean oil. The antimicrobial coatings were prepared through sol-gel hydrolysis/condensation reactions of Si-SBU mixed with different concentrations of Si-SBQ under atmospheric moisture condition. The coatings demonstrated very good hardness (202-263 s-1) and superior adhesion strength (2.25-2.95 MPa) to aluminum plate as a model metallic substrate. The biological activities of these coatings were investigated against both fibroblast cells and microorganism strains of Meticillin-resistant S. aureus, P. aeruginosa, and C. albicans. The coatings showed excellent cytocompatibility as they could support growth and proliferation of fibroblast cells (95-98% viability) on their surface. Meanwhile, they showed a high bactericidal activity against all the selected microorganisms.

A new method for estimating time since death by analysis of substances deposited on the surface of dental enamel in a body immersed in seawater.

The present investigation was performed with the objective of developing a method to estimate how long a corpse had been immersed in water after death (the time since death). Accurate determination of the time elapsed since death may lead to identification of the place of drowning, and therefore, serves not only as a piece of information useful for determination of the cause of death but also leads to prompt identification of the body. The results showed that diatoms attached to the surface of dental enamel increased with prolongation of immersion time in water. Further, as the immersion time increased, the quantity of O, Si, Mg, K, Al, and S detected on the surface of dental enamel increased, while the quantity of the main dental components (Ca and P) that were detected gradually decreased. Based on these results, we calculated a regression formula to estimate the immersion time. Our method is considered to be a breakthrough technique for evaluating the time since death more objectively, compared to the conventional method of determination based on the degree of decomposition of the corpse.

Drivers of phytoplankton blooms in the northeastern Black Sea.

In order to understand of the processes controlling phytoplankton successions in the NE Black Sea, long-term data series are needed. We compiled 15 years (2002-2017) of measurements from which the existence emerges of a tight link between phytoplankton species dominance and nutrients concentrations. The latter is strongly influenced by wind direction. The link between algal dominance and nutrients is mediated by the growth strategy adopted by algal species. In spring, when nutrients are abundant, small diatoms such as Pseudo-nitzschia pseudodelicatissima, with a "rapid growth strategy", prevail. In late spring and early summer, when N is low and P and Si are high, coccolithophorids such as Emiliania huxhleyi dominate, thanks to an "affinity growth strategy". Large diatoms, especially Pseudosolenia calcar-avis, dominate in summer and autumn, when their "storage growth strategy" allows the exploitation of discontinuous upwelling of nutrients. These seasonal changes of dominant species influence the structure of the food web.

Effects of Silicon Application on Uptake of Arsenic and Phosphorus and Formation of Iron Plaque in Rice Seedlings Grown in an Arsenic-Contaminated Soil.

Silicon (Si) plays important roles in improving rice growth and mitigating rice arsenic (As) uptake. In the present study, a pot experiment was carried out to investigate effects of Si application on uptake of As and phosphorus (P) and formation of iron (Fe) plaque on root surface of two rice cultivars (Zhendao 10 and Nanjing 44) grown in a high As-contaminated soil. The results showed that dry weights of shoots and roots for both rice cultivars didn't significantly varied under low Si level, but significantly increased for Zhendao 10, while decreased for Nanjing 44 under high Si level (p < 0.05). As concentrations in shoots and roots of Nanjing 44 significantly decreased for low Si level, while significantly increased for high Si level (p < 0.05). Different from Nanjing 44, effect of Si application on As concentrations in the plants of Zhendao 10 wasn't significant (p > 0.05). Si significantly increased concentrations of P in shoots and roots of both rice cultivars (p < 0.05). However, Si didn't significantly affect formation of Fe plaque on root surface. These results suggest that the effects of Si application on rice growth and As uptake in As-contaminated soils may depend on type of rice cultivar and Si application level. Rice cultivar and Si application rate should be considered when Si application is used to mitigate As accumulation in rice.

Nutrient dynamics and eutrophication assessment in the tropical river system of Saigon - Dongnai (southern Vietnam).

Saigon-Dongnai Rivers in Southern Vietnam is a complex lowland hydrological network of tributaries that is strongly influenced by the tidal cycles. The increasing economic, industrial and domestic developments in and around Ho Chi Minh City (HCMC) have led to serious impacts on water quality due to lack of appropriate wastewaters treatment. Drinking water production is impacted and the large aquaculture production areas may also be affected. We analyzed spatial and seasonal variability of nutrient concentrations (Phosphorus, Nitrogen and Silica) and eutrophication indicators (Organic Carbon, Chlorophyll-a and Dissolved Oxygen) based on bi-monthly monitoring during two hydrological cycles (July 2015-December 2017). Four monitoring sites were selected to assess the impact of HCMC: two upstream stations on the Saigon River and Dongnai River branches to provide the reference water quality status before reaching the urbanized area of HCMC; one monitoring station in the city center to highlight Saigon River water quality within the heart of the megacity; the fourth station downstream of the confluence to evaluate the impact of HCMC on the estuarine waters. This study points to excess nutrients in HCMC's water body with concentrations of NH4+ and PO43- averaging to 0.7 ±â€¯0.6 mgN L-1 and 0.07 ±â€¯0.06 mgP L-1, respectively in mean over the monitored period and rising up to 3 mgN L-1 and 0.2 mgP L-1, in extreme conditions. During the dry season, we evidenced that untreated domestic discharges leads to degradation of the Saigon River's water quality with extreme values of algal biomass (up 150 µChl-a L-1) and hypoxic conditions occurring episodically (DO < 2 mg L-1) in the heart of the megacity. Until now, eutrophication in the urban center has had no clear effect downstream because eutrophic water mass from the Saigon River is efficiently mixed with the Dongnai River and sea water masses during the successive semi-diurnal tidal cycles.

Impacts of maricultural activities on characteristics of dissolved organic carbon and nutrients in a typical raft-culture area of the Yellow Sea, North China.

Ailian Bay is an integrated multi-trophic aquaculture bay with approximately 60 years maricultural activities in North China. The floating raft culture of kelp and shellfish is the unique mariculture mode. In this study, the impacts of intensive mariculture activities on seasonal carbon and nutrient dynamics in Ailian Bay were systematically analysed via seasonal surveys between 2015 and 2016. The dissolved inorganic nitrogen and silicon reached the maximum concentrations during summer, which were mainly attributed to the release of shellfish metabolic by-products and their filter-feeding effects on diatoms. Dissolved organic carbon (DOC) concentrations were significantly elevated when kelps were rotting in summer and kelp seeding were occurring in winter. Meanwhile, the fluorescence intensity of humic-like chromophoric dissolved organic matter was relatively high in kelp mariculture zone. As most humic-like DOC are potentially refractory substances, we propose that kelp mariculture would contribute importantly to the increase of refractory DOC pool in oceans.

Spirulina platensis and silicon-enriched spirulina equally improve glucose tolerance and decrease the enzymatic activity of hepatic NADPH oxidase in obesogenic diet-fed rats.

The prevalence of metabolic syndrome components, such as obesity, glucose intolerance and hepatic steatosis, is rapidly increasing and becoming a major issue of public health. The present work was designed to determine the effects of Spirulina platensis (Sp) algae and silicon-enriched Sp on major metabolic syndrome components in obesogenic diet-fed rats. Forty male Wistar rats were divided into 4 groups. Ten rats were fed a control diet and 30 rats were fed a high fat (HF) diet. The HF groups were divided into three groups and supplemented with placebo or Sp or Si-enriched Sp for 12 weeks. Dietary intake and body weight were recorded. Oral glucose tolerance test and surrogate metabolic syndrome (insulin, leptin, adiponectin and lipids), mitochondrial function (enzymatic activity of respiratory chain complexes and ß-hydroxyacyl-CoA dehydrogenase), NADPH oxidase activity and several long-established oxidative stress markers were measured in the blood and liver. The HF diet induced obesity, glucose intolerance, hepatic steatosis and huge metabolic alterations, associated with higher NADPH oxidase activity and lower hepatic sulfhydryl group and glutathione contents. Otherwise, the Sp and Sp + Si supplements showed some interesting effects on rat characteristics and particularly on blood and hepatic metabolic parameters. Indeed, the intake of Sp or Sp + Si mainly improved glucose tolerance and decreased the enzymatic activity of hepatic NADPH oxidase. Overall, Si supplementation of spirulina does not appear to have more beneficial effects than spirulina alone. Other experiments with different species of rats/mice, different diets or different durations of diet intake should be undertaken to confirm or invalidate these results.

Evaluation of tolerance of tubers Solanum tuberosum to silicа nanoparticles.

In recent years, researches on the impact of nanometals on the state of soil ecosystems, including silicon, which is known to have a positive effect on plants under stressful conditions, have become relevant. The aim of this study was to assess the biological effects of nanoparticles (NP) of SiO2 on the plant Solanum tuberosum. Testing of biological activity of NP SiO2 on potato tubers was carried out on the example of five concentrations of metal increasing exponentially (0.03, 0.09, 0.18, 0.21, and 0.36 g/kg of potatoes) and control (without processing of NP SiO2). We have shown that on the 21st day of the experiment after tuber treatment, the average mass of tuber in concentrations 0.18 and 0.21 g/kg of NP SiO2 increased by 6.6% and 2.2%, respectively; stimulation of root length by 27.8-21.0%, the length of sprouts increased to 55.3%, and at a concentration of 0.36 g/kg on the 14th and 45th days, there was a maximum accumulation of Si in different parts of the plants. Analysis of chlorophyll content in the sprouts Solanum tuberosum showed that concentrations of nanoform SiO2 0.03-0.21 g/kg chlorophyll were higher than control by 48.8% and content of carotenoids by 29.7%. According to the results of field studies, the maximum mass of potato stems and tubers was observed at concentrations of 0.09 g/kg and 0.18 g/kg NP SiO2, which confirmed the absence of toxic properties of NP SiO2. The absence of the toxic effect of the investigated range of concentrations of NP SiO2 from 0.03 to 0.36 g/kg was also confirmed by electrophoretic mobility of plant DNA molecules after incubation with silicon nanoparticles in vitro.