Rhizosphere bacteria regulated arsenic bioavailability and accumulation in the soil-Chinese cabbage system.

The accumulation of arsenic (As) in Chinese cabbage (Brassica rapa ssp. pekinensis) has recently been a source of concern for a potential risk to human health. It is unknown whether natural variations of As accumulation in different genotypes of Chinese cabbage are related to rhizobacterial characteristics. Experiments were conducted to investigate the mechanisms of rhizobacteria involving in As fates in a soil-Chinese cabbage system using various genotypes using high-throughput sequencing and quantitative PCR. There were significant differences in As accumulation in cabbage leaves between 32 genotypes, and genotypes of low-As-accumulation (LSA) and high-As-accumulation (HSA) were identified. The As concentrations in the shoots of LSA were 23.25 %, 24.19 %, 15.05 %, and 70.69 % lower than those of HSA in seedling stage (SS), rosette stage (RS), heading stage (HS), and mature stage (MS), respectively. Meanwhile, the relative abundances of phyla Patescibacteria (in RS), Acidobacteria and Rokubacteria (in HS) in the rhizosphere of LSA were 60.18 %, 28.19 %, and 45.38 % less than those of HSA, respectively. Additionally, both shoot-As and As translocation factor had significantly positive or negative correlations with the relative abundances of Rokubacteria or Actinobacteria. In LSA rhizosphere, the relative abundances of genera Flavobacterium (in SS), Ellin6055 and Sphingomonas (in HS) were 128.12 %, 83.69 % and 79.50 % higher than those of HSA, respectively. This demonstrated that rhizobacteria contribute to the accumulation and translocation of As in HSA and LSA. Furthermore, the gene copies of aioA and arsM in LSA rhizosphere were 25.54 % and 16.13 % higher than those of HSA, respectively, whereas the gene copies of arsC in LSA rhizosphere were 26.36 % less than those of HSA in MS, indicating that rhizobacteria are involved in As biotransformation in the soil. These results provide a comprehensive understanding of the relationship between characteristics of rhizobacterial communities and As variations in Chinese cabbage genotypes.

Theoretical Studies and Implementation on the Temporary Data Storage Method for Cone Penetration Test.

The traditional cone penetration test system uses cable to transmit data; as the probe goes deeper into the ground, the length of the cable will become longer. This makes the installation of the test equipment more complicated, and excessively long cables cause signal distortion and seriously affect data accuracy. To simplify the experimental equipment and improve the accuracy of data acquisition, a cableless cone penetration test system is proposed. The improved system uses an SD card to store the experimental data, as opposed to using cables for communication which, often lead to the distortion of signals caused by long-distance communication and data loss caused by accidental cable breaks. Therefore, the accuracy of the collected data is higher, and the experimental device is simplified. To evaluate the applicability and efficiency of our design, we have carried out exploration experiments with the sensor system proposed in this paper. The test results show that the experimental data collected by the new system are basically consistent with the data collected by traditional cable CPT equipment, and the accuracy of the collected data is higher. It is more reliable and accurate to analyze the comprehensive mechanical properties of the soil layers with the data collected by the new system.

Roots recruited distinct rhizo-microbial communities to adapt to long-term Cd and As co-contaminated soil in wheat-maize rotation.

Cd and As accumulation in staple crops poses potential risks to food safety and human health. Rhizo-microbial communities are involved in their behaviors from soil to crops. However, the responses of rhizo-microbial communities to different Cd and As co-contaminated soils in wheat‒maize rotation are still unclear. This study explored whether wheat or maize could recruit distinct rhizo-microbial communities to adapt to long-term co-contaminated soils with low or high levels of Cd and As (LS or HS). It was apparent that the average wheat grain-Cd/As concentrations were 17.96-fold/4.81-fold in LS and 5.64-fold/7.70-fold in HS higher than those in maize grains, significantly depending on the mobility of Cd/As in soil-crop system, especially from soil to root and from straw to grain. Meanwhile, wheat or maize roots recruited specific bacteria and fungi in LS and HS, which were substantially associated with Cd/As bioavailability in rhizosphere. Wheat roots recruited specific bacterial genera norank_c__MB-A2-108 (Actinobacteria), norank_f__JG30-KF-CM45 (Chloroflexi), and norank_o__Rokubacteriales (Methylomirabilota) and fungal genera Metarhizium and Olpidium under HS, and their relative abundances were positively correlated with soil Cd/As bioavailability and were resistant to Cd and As co-contamination. However, bacterial genera Arthrobacter, Nocardioides, Devosia, Skermanella, and Pedobacter were sensitive to Cd and As co-contamination and were specifically enriched in wheat rhizospheres under LS. Meanwhile, the bacterial genus norank_c__KD4-96 (Chloroflexi) was resistant to Cd and As co-contamination under HS and was distinctly enriched in maize rhizosphere. Furthermore, the roots of wheat and maize recruited the bacterial genus Marmoricola in LS, which was sensitive to Cd and As co-contamination, and recruited specific fungal genus Fusicolla in HS, which was tolerant to Cd and As co-contamination. These results confirmed that HS and LS shifted the composition and structure of the rhizo-microbial communities in the wheat-maize rotation to promote crops survival in different long-term Cd and As co-contaminated soils.

[Blocking Effects of Foliar Conditioners on Cadmium, Arsenic, and Lead Accumulation in Wheat Grain in Compound-contaminated Farmland].

Heavy metal contamination of soil has become a hot issue of social concern due to its impact on the safety of agricultural products in recent years. Wheat is one of the most dominant staple food crops worldwide and has become a major source of toxic metals in human diets. Foliar application was considered to be a more efficient and economical method of heavy metal remediation. Field experiments were carried out in Cd-, As-, and Pb-contaminated farmland soils. The effects of foliar conditioners on the accumulation of Cd, As, and Pb in wheat grains were investigated after being sprayed with Zn (0.2% ZnSO4), Mg (0.4% MgSO4), and Mn (0.2% MnSO4) separately and in combination. Thus, the effective foliar conditioners were selected to block the accumulation of Cd, As, and Pb in wheat grains grown in combined heavy metal-contaminated farmland in north China. The results showed that, compared with that in the control, the Cd, As, and Pb contents in wheat grains of the Zn+Mg+Mn foliar treatment were significantly decreased by 18.96%, 23.87%, and 51.31%, respectively, and TFgrain/straw decreased by 14.62%, 27.73%, and 47.70%, respectively. Thus, spraying the compound foliar conditioner of Zn+Mg+Mn could effectively reduce heavy metal accumulation in wheat grains through inhibition translocation of those metals from stem leaves to grain. In addition, the results indicated that Cd and As were mainly distributed at the central endosperm (34.08%-37.08%), whereas Pb was primarily distributed at the pericarp and seed coat (27.78%) of the wheat grain. Compared with that in the control, spraying the compound foliar conditioner of Zn+Mg+Mn extremely decreased Cd and As accumulation in the aleurone layer of the wheat grain by 81.10% and 82.24%, respectively. Except for the pericarp, seed coat, and central endosperm layers, the Pb content in each grain layer was dramatically decreased by 42.85% to 91.15%. There was only a significant negative correlation between heavy metal content and Zn content in the aleurone layer (P2) of wheat flour. In summary, the accumulation of Cd, As, and Pb in wheat grains, especially in the aleurone layer, could be effectively reduced by foliar conditioner application at the jointing, booting, and early filling stages of wheat, separately. Furthermore, besides the foliar treatment, removing wheat bran to reduce Cd contamination in wheat grains is highly recommended to ensure the safe production of wheat.

Foliar uptake screening: A promising strategy for identifying wheat varieties with low lead accumulation.

Lead (Pb) contamination in wheat grain is of great concern, especially in North China. Atmospheric deposition is a major contributor to Pb accumulation in wheat grain. Screening low Pb accumulating wheat varieties has been an effective method for addressing Pb contamination in wheat grain. However, identifying wheat varieties with low Pb accumulation based on foliar uptake of atmospheric Pb has been neglected. Therefore, two field trials with distinct atmospheric Pb deposition were conducted to screen for stable varieties with low Pb accumulation. It was verified that YB700 and CH58, which have high thousand-grain weights and stable low Pb accumulation in field 1 (0.19 and 0.13 mg kg-1) and field 2 (0.17 and 0.20 mg kg-1), respectively, were recommended for cultivation in atmospheric Pb contaminated farmlands in North China. Furthermore, indoor experiments were conducted to investigate Pb uptake by the roots and leaves of different wheat varieties. Our findings indicate that Pb accumulation in different wheat varieties is primarily influenced by foliar Pb uptake rather than root Pb uptake. Interestingly, there was a positive correlation (p < 0.05) between the Pb concentrations in leaves and the stomatal width and trichome length of the adaxial epidermal surface. Additionally, there is a positive correlation (p < 0.01) between the Pb concentration in the wheat grain and trichome length. In conclusion, the screening of wheat varieties with narrower stomatal widths or shorter trichomes based on foliar uptake pathways is an effective strategy for ensuring food safety in areas contaminated by atmospheric Pb.

Transcriptomic mechanisms of reduced PM2.5-Pb retention in the leaves of the low-Pb-accumulation genotype of Chinese cabbage.

Atmospheric fine particulate matter (PM2.5) mainly contributes to Pb accumulation in the edible leaves of Chinese cabbage in North China. It was found that a low-Pb-accumulation (LPA) genotype of Chinese cabbage contained less Pb in leaves than high-Pb-accumulation (HPA) genotype exposed to PM2.5-Pb. However, there are no data on the transcriptional regulatory mechanisms of foliar PM2.5-Pb uptake by Chinese cabbage. The present study investigated the retention of PM2.5-Pb in foliar apoplast and symplasm and the underlying molecular mechanisms of reduced Pb in LPA leaves. It appeared more Pb in apoplast and less Pb in symplasm of LPA leaves, whereas the pattern was opposite in HPA. There were 2646 and 3095 differentially expressed genes (DEGs) in LPA and HPA leaves under PM2.5-Pb stress with clearly genotype-specific function, respectively. Furthermore, mRNA levels of XTH16 regulating cell wall thickening, PME2 and PME6 involved in cell wall remodification were significantly expressed in LPA, but not in HPA. Meanwhile, foliar PM2.5-Pb stress downregulated expression of ZIP1, YSL1, and CNGC3 responsible for Pb influx to cell, and upregulated expression of ABCG36 regulated Pb efflux from symplasm in LPA leaves. These results improve our understanding to the mechanisms underlying foliar Pb uptake from PM2.5-Pb at transcriptomic level.

Mechanism of Pb accumulation in Chinese cabbage leaves: Stomata and trichomes regulate foliar uptake of Pb in atmospheric PM2.5.

Chinese cabbage (Brassica rapa ssp. pekinensis) is one of the most popular and frequently consumed leafy vegetables. It was found that atmospheric PM2.5-Pb contributes to Pb accumulation in the edible leaves of Chinese cabbage via stomata in North China during haze seasons with high concentrations of fine particulate matter in autumn and winter. However, it is unclear whether both stomata and trichomes co-regulate foliar transfer of PM2.5-Pb from atmospheric deposition to the leaf of Chinese cabbage genotypes with trichomes. Field and hydroponic experiments were conducted to investigate the effects of foliar uptake of PM2.5-Pb on Pb accumulation in leaves using two genotypes of Chinese cabbage, one without trichomes and one with trichomes. It was verified that open stoma is a prominent pathway of foliar PM2.5-Pb transfer in the short-term exposure for 6 h, contributing 74.5% of Pb accumulation in leaves, whereas Pb concentrations in the leaves of with-trichome genotype in the rosette stage were 6.52- and 1.04-fold higher than that of without-trichome genotype in greenhouse and open field, respectively, which suggests that stomata and trichomes co-regulate foliar Pb uptake of from atmospheric PM2.5. Moreover, subcellular Pb in the leaves was distributed in the following order of cytoplasm (53.8%) > cell wall (38.5%)> organelle (7.8%), as confirmed through high-resolution secondary ion mass spectrometry (NanoSIMS). The Leadmium™ Green AM dye manifested that Pb in PM2.5 entered cellular space of trichomes and accumulated in the basal compartment, enhancing foliar Pb uptake in the edible leaves of cabbage. The results of these experiments are evidence that both stomata and trichomes are important pathways in the regulation of foliar Pb uptake and translocation in Chinese cabbage.

An integration-free iPSC line SDQLCHi025-A from a girl with multiminicore disease carrying compound heterozygote mutations in RYR1 gene.

Peripheral blood mononuclear cells for reprogramming in this work were donated by a girl with clinically and genetically diagnosed multiminicore disease harboring compound heterozygote mutations of RYR1 gene. Induced pluripotent stem cells (iPSCs) were obtained by non-integrating episomal vectors containing OCT4, SOX2, KLF4, BCL-XL and c-MYC. The iPSC line (SDQLCHi025-A) presented pluripotent cell morphology, high mRNA levels of pluripotency markers, differentiation potential in vitro, a normal karyotype, and carrying RYR1 gene mutations.

Spraying silicon to decrease inorganic arsenic accumulation in rice grain from arsenic-contaminated paddy soil.

Addition of Si to soil can reduce As uptake and accumulation in rice, while also enhancing As release from soil particles via competing sorption sites in soil minerals with As. Foliar application of Si might be an alternative pathway to reduce As accumulation in rice. It is not clear which growing stage would be better for spraying different types of Si solution to reduce inorganic As in edible parts of rice. Soil pot experiments were conducted to investigate whether total As and inorganic As accumulation in rice grains was alleviated via spraying Si in As-contaminated paddy soil. The results showed that foliar Si application at the tillering or jointing stage significantly reduced As concentrations in rice husks and grain via inhibiting the translocation of As from straw to husk or grain compared with other growing stages. Spraying of Si at the tillering stage markedly decreased the concentrations of inorganic As in rice bran and polished rice, accounting for 27.3% and 61.4% respectively. Furthermore, spraying Si solution mixed with surfactant-Tween 80 not only dramatically reduced the total As in rice tissues by 48.8%, but also significantly alleviated the accumulation of inorganic As in rice grain by 49.2%. Spraying Si restricted inorganic As in rice grain through the mechanism by which foliar Si application at tillering stage increased the Si concentrations in shoot and root, which downregulated Si transporters of Lsi1 and Lsi2 in the root and Lsi6 in the blade and sheath significantly, and finally decreased As uptake and transport. Therefore, spraying Si is an alternative and efficient pathway to reduce inorganic As accumulation of rice grain in As-contaminated soil.

Characteristics of heavy metals in soils and grains of wheat and maize from farmland irrigated with sewage.

The farmland irrigation with the sewage is a common and better pathway to save the resource of groundwater in Northern China. The investigation was conducted in the farmland along the Fuhe River to explore characteristics of heavy metals in soils and grains of wheat and maize from a long-term sewage-irrigated area of Baoding region. The results showed that the topsoil with long-term sewage irrigation accumulated more Cd, Pb, and Hg compared with that of soil irrigated with groundwater and their corresponding natural background values. Cd concentrations in 48% of sewage-irrigated soil samples exceeded the Chinese safety limitation at 0.6 mg/kg, but less Cd accumulated in crop grains and did not pose the potential health risk. On the contrary, Pb levels in soils irrigated with sewage were lower than the safety limitation but Pb concentrations in 24% of wheat grain samples exceeded the Chinese national safety limit. Long-term sewage irrigation did not increase As, Cr, and Ni concentrations in soils or crop grains. The target hazard quotient (THQ) of heavy metals in edible grains of crops was selected to assess their risk to human health. Total THQ values were higher than 1.0 for the wheat samples from sewage-irrigated area and both sewage-irrigated and smelter-impacted areas, and As is the main contributor to the total THQ and posed the potential risk to human health. Therefore, the accumulation of Cd, Pb, Hg, and As in soils and crops in sewage-irrigated area should be monitored continuously to ensure food safety and security.

Do Si/As ratios in growth medium affect arsenic uptake, arsenite efflux and translocation of arsenite in rice (Oryza sativa)?

Silicon (Si) may decrease the uptake and accumulation of arsenic (As) in rice. However, the effects of Si/As ratios in growth medium on arsenic uptake, arsenite efflux to the external medium and translocation of arsenite in rice are currently unclear. Rice seedlings (Oryza sativa L.) were exposed to nutrient solutions with 10 µM arsenite [As(III)] or 10 µM arsenate [As(V)] to explore the influence of different silicic acid concentrations (0, 10, 100, 1000 µM) on arsenic uptake and translocation of arsenite with or without 91 µM phosphate for 24 h. Arsenic speciation was determined in nutrient solutions, roots, and shoots. In the arsenite treatments, different Si/As ratios (1:1, 10:1, 100:1) did not affect As(III) uptake by rice roots, however they did inhibit translocation of As(III) from roots to shoots significantly (P < 0.001) in the absence of P. In the arsenate treatments, a Si/As ratio of 100:1 significantly decreased As(V) uptake and As(III) efflux compared with the control (Si/As at 0:1), accounting for decreases of 27.4% and 15.1% for -P treatment and 47.8% and 61.1% for + P treatment, respectively. As(III) is the predominant species of arsenic in rice roots and shoots. A Si/As ratio of 100:1 reduced As(III) translocation from roots to shoots markedly without phosphate. When phosphate was supplied, As(III) translocation from roots to shoots was significantly inhibited by Si/As ratios of 10:1 and 100:1. The results indicated that in the presence of P, different silicic acid concentrations did not impact arsenite uptake and transport in rice when arsenite was supplied. However, a Si/As ratio of 100:1 inhibited As(V) uptake, as well as As(III) efflux and translocation from roots to shoots when arsenate was supplied.

rs5911 and rs3842788 Genetic Polymorphism, Blood Stasis Syndrome, and Plasma TXB2 and hs-CRP Levels Are Associated with Aspirin Resistance in Chinese Chronic Stable Angina Patients.

The identification of single nucleotide polymorphisms (SNPs) related to aspirin resistance (AR) is of great significance for the explanation why some individuals demonstrate an incomplete response to aspirin and for optimizing the antiplatelet therapy strategy. The study was designed to investigate the possible associated genetic markers and clinical factors of AR for Chinese patients with chronic stable angina after PCI and to analyze the association between TXA2, PGI2, hs-CRP level, AR, and gene polymorphisms. Totally 207 chronic stable angina patients who received 100 mg maintenance dose daily of aspirin for more than 7 days were enrolled. The inhibition of platelets was assessed using light transmittance aggregometry. TXB2, 6-keto-PGF1α, and hs-CRP were measured by radioimmunoassay. Genotyping was performed using Taqman probe technique (rs5787 and rs5911) and gene sequencing technology (rs3842788). By using binary logistic regression analysis, the impact of clinical and genetic determinants on AR was evaluated. The prevalence of AR and aspirin semiresistance (ASR) was 3.86% and 20.76%, respectively, in Chinese chronic stable angina patients. rs5911 A/C and C/C versus A/A genotype (OR = 5.546, 95% CI = 1.812-11.404), rs3842788 A/G versus G/G genotype (OR = 8.358, 95% CI = 2.470-28.286), and blood stasis syndrome (BSS, OR = 10.220, 95% CI = 4.242-24.621) were associated with AR, but rs5787 variants were all homozygous of G/G genotype. Plasma TXB2 and hs-CRP increased significantly in AR and ASR group, while 6-keto-PGF1α showed no difference, and TXB2 level was significantly higher in carriers of the rs3842788 A/G genotype. According to our results, rs5911 and rs3842788 are proved to be specific genetic markers of AR in Chinese chronic stable angina patients for the first time, and BSS was also proved to be a remarkable determinant for AR. The AR and ASR patients were with increased plasma TXB2 and hs-CRP levels, and the TXB2 level was influenced by the variation of rs3842788 genotype.

The Effect of Xuefuzhuyu Oral Liquid on Aspirin Resistance and Its Association with rs5911, rs5787, and rs3842788 Gene Polymorphisms.

Aspirin should be continued indefinitely in patients after interventional therapy, but 10% to 40% of patients experience recurrent vascular events despite adequate aspirin therapy, a condition known as aspirin resistance (AR). Xuefuzhuyu oral liquid, derived from the classic recipe Xuefuzhuyu decoction, has been well documented to inhibit platelet aggregation and to improve hemorheology. The aims of this study were to investigate the effects of Xuefuzhuyu oral liquid on AR in patients with chronic stable angina after percutaneous coronary intervention (PCI) and the possible genetic markers related to the drug response. 43 patients diagnosed as having aspirin resistance or semi-resistance were randomly divided into control and treatment groups after screening 207 stable CHD patients. Platelet aggregation rate was determined using turbidimetry. Three single nucleotide polymorphisms in COX-1 (rs5787, rs3842788) and GP IIb (rs5911) were genotyped in whole blood samples using ABI PRISM 7900 HT Fast Real-Time instrument and ABI PRISM 3730 DNA Sequencer. The results showed that Xuefuzhuyu oral liquid could effectively improve blood stasis syndrome and AR by inhibiting ADP-induced platelet aggregation and that patients with the rs5911 genetic variant exhibited better drug response upon treatment with Xuefuzhuyu oral liquid, which suggests Xuefuzhuyu oral liquid as a new possible drug for the prevention of AR.

[Mechanisms of copper uptake by submerged plant Hydrilla verticillata ( L. F. ) royle and Myriophyllum spicatum L].

Cultivation experiments, including short-term copper uptake kinetics, uptake kinetics of Cu by different subcellular fractions and efflux of Cu, were carried out to investigate mechanisms of copper uptake by two species of submerged macrophyte, Hydrilla verticillata (L. f. ) Royle and Myriophyllum spicatum L. The results showed that: (1) Both H. verticillata and M. spicatum showed high influx rates for copper ions with no statistically significant differences [ Vmax (DW) is 2 micromol. (g min) - 1] ; (2) Both leaf and stem Cu concentrations of two strains of plants showed sharp increase with the external medium, and the equilibrium was reached for about 12 h after being exposed to solution with 2 micromol L-1 Cu. Leaves of these two plants accumulated much higher concentrations of Cu than stems. Furthermore, Cu in leaves concentrated predominantly in cell walls ( > 60% ) , followed by soluble and organell fractions; (3) Copper accumulated in cell wall of H. verticillata leaf was considerably higher than that of M. spicatum, and Cu concentrated in intracellular fractions of leaves showed no statistically significant difference between these two plants. Moreover, ability of Cu accumulation and efflux by H. verticillata was higher than that by M. spicatum.

Arsenic speciation in Chinese Herbal Medicines and human health implication for inorganic arsenic.

Rice and drinking water are recognized as the dominant sources of arsenic (As) for human intake, while little is known about As accumulation and speciation in Chinese Herbal Medicines (CHMs), which have been available for many hundreds of years for the treatment of diseases in both eastern and western cultures. Inorganic arsenic was the predominant species in all of CHMs samples. The levels of inorganic arsenic in CHMs from fields and markets or pharmacies ranged from 63 to 550 ng/g with a mean of 208 ng/g and 94 to 8683 ng/g with a mean of 1092 ng/g, respectively. The highest concentration was found in the Chrysanthemum from pharmacies. It indicates that the risk of inorganic As in CHMs to human health is higher in medicines from markets or pharmacies than that collected directly from fields. Some CHMs may make a considerable contribution to the human intake of inorganic arsenic.

[Effects of arsenic from soil and irrigation-water on As accumulation on the root surfaces and in mature rice plants (Oryza sativa L.)].

A compartmented soil-glass bead culture system was used to investigate characteristics of arsenic accumulation in iron plaque and in mature rice plants irrigated using water with arsenic in greenhouse. Arsenic was supplied as a solution of Na3AsO4 * 12H2O at the following stages: tillering, stem elongation, booting, flowering and grain filling. The whole plant was separated into four parts and As concentrations were analyzed in DCB (dithionite-citrate-bicarbonate)-extraction, root, straw, rice husk and grain respectively. The results show that irrigation-water with arsenic has no significant effect on biomass of straw and grain. Arsenic concentrations are distributed in different components of mature rice with the ranking of iron plaque > root > straw > husk > grain. Arsenic in straw and grain just derive from soil in control, and derive from soil and irrigation-water in arsenic treatment. About 76.5% and 71.0% of total arsenic in rice straw are from soil for lines of YY-1 and 94D-64 respectively. There is no significant difference between two lines. However, about 33.6% of total arsenic in grain of YY-1 comes from irrigation-water with arsenic, and only 15.2% of total arsenic in grain of 94D1-64 is from irrigation-water with arsenic. There is a significant difference between YY-1 and 94D-64. Arsenic concentrations in rice grain are lower than the food safety limitation in China (0.7 mg x kg(-1)).