Chloride application weakens cadmium immobilization by lime in paddy rice soil.

Contamination of agricultural products by cadmium (Cd) is a global health problem, causing chronic abnormalities. The consumption of rice, the most-consumed foods, is an important exposure route of Cd to human body. Chloride (Cl-) is reported to increase Cd uptake by rice; however, the effect on Cd uptake and accumulation by rice in the presence of lime is not clear. Therefore, a pot culture experiment was performed to explore the influence of Cl- on the absorption and accumulation of Cd in rice plants under lime remediation and its possible mechanisms. The results showed that Cl- promoted Cd accumulation in rice grains, mainly because of increased Cd bioavailability in the soil and by impeding the formation of iron plaques on rice roots, which reduced chelating and precipitation of Cd. Moreover, increased overexpression of the main transporters of Cd in rice roots, including OsNramp5, OsNramp1, OsIRTs and OsHMA2, favored the upward translocation of Cd from the root to shoot and increased the transfer factors (TFs) from soil to root, root-stem, leaf to grain, and soil to grain. Therefore, the application of Cl-rich materials to Cd-contaminated rice fields should be avoided during liming of the soil for Cd immobilization.

Effects and mechanisms of Cd remediation with zeolite in brown rice (Oryza sativa).

The effects of zeolite amendment on the Cd absorption and accumulation of two varieties of rice, ZY-18 (Zheyou 18, hybrid indica) and DL-5 (Donglian 5, conventional indica), planted in a slightly Cd-contaminated paddy soil, and the associated mechanisms were studied based on a pot experiment. The results showed that zeolite addition significantly reduced the Cd availability in the soil by the increasing of soil pH and the Cd sorption capacity of soil, as well as the reduction of Eh, dissolved organic carbon (DOC) and the water-soluble Fe/Mn in the soil. The decrease in the amount of Fe and Cd in iron plaques on rice roots treated with zeolite resulted in the reduction of Cd uptake by rice roots. Zeolite application decreased the Cd contents in the roots, stems and leaves, and finally the brown rice through the inhibition of uptake and translocation of Cd by rice plant. The Cd concentration in rice grains of ZY-18 was more decreased than that of DL-5, which was attributed to its higher pH and lower Eh, DOC, and Cd availability in the soil, higher mounts of iron plaque and Cd in plaques on rice roots, and lower root-to-grain transfer factor (TFroot-grain) of ZY-18.

[Application of remote sensing technology in medicinal plant resources].

The sustainable use of medicinal plants is the foundation of the inheritance of traditional Chinese medicine(TCM) and the acquisition of information on medicinal plants is the basis for the development of TCM. The traditional methods of investigating medicinal plant resources are disadvantageous in strong subjectivity and poor timeliness, making it difficult to real-time monitor medicinal plant resources. In recent years, remote sensing technology has become an important means of obtaining information on medicinal plants. The application of this technology has made up for the shortcomings of traditional methods. The open-access remote sensing data with medium spatial resolution satellites provide an opportunity for extracting information on medicinal plant resources. This study firstly introduced the principles of remote sensing technology, summarized the satellites and the parameters commonly used in the field of medicinal plant resources, and compared the survey methods of remote sensing technology with traditional methods. Secondly, it reviewed the applications of remote sensing technology in the extraction of information on the cultivation of medicinal plants and the common methods for extracting the planting structure information of medicinal plants based on remote sensing technology. Thirdly, the applications of remote sensing technology in the investigation and monitoring of medicinal plants were further analyzed with the research objects divided into wild and cultivated medicinal plants according to the characteristics of the habitats. Finally, it pointed out the key unsolved technical problems in the remote sensing monitoring of medicinal plant resources, and proposed solutions for the intelligent information processing of medicinal plants based on remote sensing big data, which is expected to provide references for the development of remote sensing technology in derivative application in medicinal plant resources.

Assessment of Cd availability in rice cultivation (Oryza sativa): Effects of amendments and the spatiotemporal chemical changes in the rhizosphere and bulk soil.

Immobilization is widely used to decrease the availability of heavy metals, such as Cd and Pb, in contaminated soils. However, the spatial and temporal changes in the immobilization of soil by amendments combined with planting effects have not been studied well. In this study, unplanted and planted (with rice plants) pot experiments were used to assess the spatial and temporal changes in water-soluble Cd, Fe, Mn, and Ca. Soil properties, such as pH, redox potential (Eh), and dissolved organic carbon (DOC), were continuously recorded in both the rhizosphere and bulk soil using non-invasive rhizon samplers and a microelectrode system (Unisense). In unplanted soil, pH and Eh varied with time, but showed little radial variation from the rhizosphere to the bulk soil. The addition of hydrated lime (Ca(OH)2) sharply increased the pH, DOC, and Ca content; decreased the Eh, Fe content, and Mn content; and gradually decreased the water-soluble Cd content in the soil profile. Hydroxyapatite showed no obvious effects in reducing Cd concentrations in different soil zones. The water-soluble Fe, Mn, Ca, and DOC content did not differ significantly between soil zones over time and a non-significant correlation with water-soluble Cd was shown. In planted soil, the pH increased while the Eh value decreased with an increase in the distance from the roots, regardless of the soil amendments used during the rice growth period. Hydroxyapatite gradually increased but hydrated lime decreased the water-soluble Cd in the rhizosphere. The concentration of water-soluble Cd in the rhizosphere was higher than that of the other soil zones during rice growth. These changes lead to more Cd uptake by roots and induced Cd accumulation in rice tissues. In addition, Cd and Fe concentration in iron plaque showed a significant positive correlation with Cd in rice, indicating that iron plaque promotes the uptake and accumulation of Cd in rice with soil amendments. Compared with the control, hydroxyapatite did not significantly affect the Cd content, while Ca(OH)2 significantly reduced the Cd content in iron plaque and rice tissues. In conclusion, the application of hydrated lime can significantly reduce the risk of Cd accumulation by rice in Cd-contaminated soils under flooding conditions.

Dynamics of the rice rhizosphere microbial community under continuous and intermittent flooding treatment.

Flooding regime is an important agronomic strategy, and widely applied in heavy metal-contaminated soil for controlling heavy metal uptake through biochemical processes. However, the dynamics of the microbial community in the rhizosphere of rice under different flooding systems are not well understood. In the present study, we investigated the dynamics between the microbial community and heavy metal ions under continuous flooding (CF) and intermittent flooding (IF) conditions to decipher the relationship between microbial community and environmental factors. The results showed that, for the complex Cd, Pb, and Zn contaminated soil under CF treatment did not significantly suppress Cd uptake, but promoted Pb and Ni accumulation into the rice root. Soil pH and bio-available phosphate content appeared to be the key factors impacting heavy metal mobility. When observing the microbial community in the rhizosphere, long term flooding resulted in an abundance of Anaeromyxobactersp., Geobacter and Desulfovibrio, and the abundance of these taxa displayed a significant relationship to Pb and Zn content of rice roots. From the study, we observed that the flooding regime could have a significant impact on concentrations of Cd, Pb and Ni in rice roots, and the different richness of SRB and FeRB may contribute to uptake of these heavy metals. In future work, the impact of Fe cycling on heavy metal bioavailability in the plant rhizosphere should be investigated further.

Expression and immunogenicity of recombinant glycoprotein D of herpes simplex virus 1 in Drosophila S2 cells.

Herpes simplex virus type 1 (HSV-1) is responsible for cold sores in the general population, but also contributes to the development of other more serious diseases in some circumstances. The viral glycoprotein D (gD) is essential for virus entry into host cells. In the present study, the Drosophila melanogaster Schneider 2 (S2) expression system (DES) was evaluated for the expression of recombinant gD1. The DNA sequences encoding the full-length gD1 (369aa, FLgD1) and a truncated gD1 form corresponding to the ectodomain (314aa, EgD1) were cloned into S2 expression vector pMT/BiP/V5-HisA to generate pMT-EgD1 and pMT-FLgD1, respectively. Two forms of gD1 gene were fitted with a hexahistidine tag to facilitate their purification. Cell populations expressing the highest gD1 levels were selected by using a limiting dilution assay. Western blot, flow cytometry (FACS), and confocal immunofluoresence assay demonstrated that the full-length form is restrained in the lipid membranes of the cell and the ectodomain form is secreted into the medium. Recombinant ectodomain gD1 was scaled up and purified from the culture medium using nickel nitrilotriacetic acid affinity chromatography, and a maximum production level of 56.8 mg/L of recombinant gD1 was obtained in a shake-flask culture of S2 cells after induction with 5 µM CdCl2 for 4 days. Mice were then immunized with recombinant purified gD1 and produced high titers of antibody measured by enzyme-linked immunosorbent assay (ELISA; 1:5,120,000) as well as high plaque neutralization titer (1:320). Overall, the data indicated that stable expression in S2 cells is a practical way of synthesizing gD1 for use in structural and functional studies in the further study.

Usefulness of serum thyroid-stimulation hormone (TSH) as a prognostic indicator for acute-on-chronic liver failure.

UNLABELLED: BACKGROUND AND RATIONALE FOR THE STUDY: To investigate thyroid function in patients with acute-on-chronic liver failure (ACLF) caused by hepatitis B virus infection and to determine whether thyroid hormone levels can be used as prognostic markers for assessing severity and prognosis of ACLF patients. We enrolled 75 patients with ACLF and70 patients with chronic hepatitis B (CHB). Continual serum samples were collected during hospitalization from the ACLF patients. The serum thyroid hormone levels (triiodothyronine [T3], thyroxine [T4], free (F)-T3, FT4, and thyroid stimulation hormone [TSH]) were measured by chemiluminescence. The Model for End-stage Liver Disease (MELD) score was used to assess severity. RESULTS: ACLF patients showed significantly (p < 0.001) lower values of serum T3, T4, FT3/FT4 and TSH than CHB patients. The T3, T4, and TSH levels in ACLF patients were negatively correlated with the MELD score (T3: r = -0.495, p < 0.001; T4: r = -0.281, p < 0.001; TSH: r = -0.498, p < 0.001), suggesting that serum thyroid hormone levels reflect disease severity. At 1 year, 31 patients died. The T3 (p = 0.016), T4 (p = 0.008), and TSH (p = 0.003) levels in non-survivors were significantly lower than in survivors. The serum TSH level was a significant factor for predicting mortality in ACLF patients (optimal cutoff value = 0.38 IU/mL). The cumulative survival rate was decreased significantly when the serum TSH level was < 0.38 IU/mL (39.2%, p < 0.001). CONCLUSION: Serum TSH level may be a useful indicator for assessing severity and prognosis in ACLF patients.

[Research of estimation methods on medicinal plant resources reserves].

The medicinal plant resource reserve refers to the natural resources of medicinal plants in a certain time and a certain region within the scope of the volume. In recent years, with the demand of medicinal plant resources surging and the change of the environment and human intervention factors, the medicinal plant resources reserve had accelerated pace of change. It is the prerequisite and basis for the development and utilization of medical plants that how to quickly and accurately attain reserve of some medicinal plants resources, the selection of suitable and accurate estimating method is reliable basis and can guarantee medicinal plant reserve survey, and also is one of the key reserve investigation of success. This paper systematically summarized the estimation method of medicinal plants in recent 30 years, and discussed the basic principle, the estimation model of development and evolution, advantages and disadvantages and applicability, and it aimed to improve the accuracy about reserves survey of medicinal plant resources, and provide scientific and reliable support data to medicinal plants resources for sustainable development and utilization of resources.

Mechanisms of chloride to promote the uptake and accumulation of cadmium in rice (Oryza sativa L.).

Cadmium (Cd) contamination in rice ecosystems posed a critical challenge to global food security and environmental health. This study aimed to unveil the key mechanisms trough hydroponic experiments by which chloride (Cl-) promoted the absorption and accumulation of cadmium (Cd) in rice plants. The findings elucidated that the addition of Cl- increased Cd uptake by rice roots (5.1 % âˆ¼ 61 %), acting both directly by enhancing root morphology and indirectly through regulating of the main transporter genes of Cd. The study unveiled that Cl- addition significantly improves Cd bioavailability in roots, which was discernible through the augmentation of Cd concentration and proportion in subcellular fractions, coupled with elevated energy values in key cellular components. Moreover, Cl- addition further augmented the intricate process of Cd transport from roots to shoots (16.1- 86.7 %), which was mainly attributed to the underexpression of OsHMA3 and the decrease in the formation of sulfuhydryl substances. This research provides a comprehensive understanding of the complex mechanisms governing Cd dynamics in rice plants in the presence of Cl-. By elucidating these processes, our findings not only contribute to fundamental knowledge in plant metal uptake but also hold promising implications for mitigating Cd contamination in rice cultivation systems.

An ethnobotanical survey on the medicinal and edible plants used by the Daur people in China.

BACKGROUND: The Daur people are one of the 55 minority ethnic groups in China and have lived in Northern China for 300 years. In traditional Daur medicine, medicinal and edible plants (MEPs) are utilised for health benefits and therapeutic purposes; however, related ethnobotanical knowledge is rarely reported, which is disadvantageous for the sustainable development of these MEPs. METHODS: Semi-structured interviews with 122 informants, six focus group discussions, and a resource survey were conducted in a Daur minority nationality area in Inner Mongolia from 2015 to 2020, and the data statistics were analysed. In this study, we simulated a system dynamics model aimed at understanding the multiple feedback mechanisms involved in the relationships between the cultural influences and socioeconomic factors, sustainable environment, and development of MEPs. RESULTS: A total of 52 species of MEPs were identified and relevant ethnobotanical knowledge was assessed using Daur medicinal species data from Inner Mongolia and the Xinjiang region, with the literature and Ewenki ethnic group data used for comparison. The most commonly used medicinal plant species by the Daur were found to be Betula pendula subsp. mandshurica, Artemisia integrifolia, Crataegus pinnatifida, Saposhnikovia divaricata, Artemisia argyi, and Jacobaea cannabifolia. The MEPs most frequently targeted the digestive and rheumatic immunity systems, as well as infectious diseases or parasitic infections and other common diseases and basic health issues. MEP knowledge was primarily limited to older generations; thus, the valuable ethnobotanical knowledge on traditional medicines must be protected from future losses. CONCLUSIONS: Our findings provide insights for future research aimed at exploiting the rich phytochemical diversity in traditional medicine and promote its use in modern lifestyles. Effective assessment and management of plant resources will lead to their application for the improvement of dietary diversity, nutrition, and health care.

Response to HIV-1 gp160-carrying recombinant virus HSV-1 and HIV-1 VLP combined vaccine in BALB/c mice.

Human immunodeficiency virus (HIV) induced AIDS causes a large number of infections and deaths worldwide every year, still no vaccines are available to prevent infection. Recombinant herpes simplex virus type 1 (HSV-1) vector-based vaccines coding the target proteins of other pathogens have been widely used for disease control. Here, a recombinant virus with HIV-1 gp160 gene integration into the internal reverse (IR) region-deleted HSV-1 vector (HSV-BAC), was obtained by bacterial artificial chromosome (BAC) technology, and its immunogenicity investigated in BALB/c mice. The result showed similar replication ability of the HSV-BAC-based recombinant virus and wild type. Furthermore, humoral and cellular immune response showed superiority of intraperitoneal (IP) administration, compared to intranasally (IN), subcutaneous (SC) and intramuscularly (IM), that evidenced by production of significant antibody and T cell responses. More importantly, in a prime-boost combination study murine model, the recombinant viruses prime followed by HIV-1 VLP boost induced stronger and broader immune responses than single virus or protein vaccination in a similar vaccination regimen. Antibody production was sufficient with huge potential for viral clearance, along with efficient T-cell activation, which were evaluated by the enzyme-linked immunosorbent assay (ELISA) and flow cytometry (FC). Overall, these findings expose the value of combining different vaccine vectors and modalities to improve immunogenicity and breadth against different HIV-1 antigens.

Transformer based on channel-spatial attention for accurate classification of scenes in remote sensing image.

Recently, the scenes in large high-resolution remote sensing (HRRS) datasets have been classified using convolutional neural network (CNN)-based methods. Such methods are well-suited for spatial feature extraction and can classify images with relatively high accuracy. However, CNNs do not adequately learn the long-distance dependencies between images and features in image processing, despite this being necessary for HRRS image processing as the semantic content of the scenes in these images is closely related to their spatial relationship. CNNs also have limitations in solving problems related to large intra-class differences and high inter-class similarity. To overcome these challenges, in this study we combine the channel-spatial attention (CSA) mechanism with the Vision Transformer method to propose an effective HRRS image scene classification framework using Channel-Spatial Attention Transformers (CSAT). The proposed model extracts the channel and spatial features of HRRS images using CSA and the Multi-head Self-Attention (MSA) mechanism in the transformer module. First, the HRRS image is mapped into a series of multiple planar 2D patch vectors after passing to the CSA. Second, the ordered vector is obtained via the linear transformation of each vector, and the position and learnable embedding vectors are added to the sequence vector to capture the inter-feature dependencies at a distance from the generated image. Next, we use MSA to extract image features and the residual network structure to complete the encoder construction to solve the gradient disappearance problem and avoid overfitting. Finally, a multi-layer perceptron is used to classify the scenes in the HRRS images. The CSAT network is evaluated using three public remote sensing scene image datasets: UC-Merced, AID, and NWPU-RESISC45. The experimental results show that the proposed CSAT network outperforms a selection of state-of-the-art methods in terms of scene classification.

Oyster shell amendment reduces cadmium and lead availability and uptake by rice in contaminated paddy soil.

Contamination with cadmium (Cd) and lead (Pb) in rice and paddy soil threatens food safety and human health. This study determined the effects of oyster shell amendment (0, 6, and 12 g kg-1) on the mobility and uptake of Cd and Pb by two rice plants (ZY18, japonica and DL5, indica) in contaminated paddy soil. Oyster shell amendment significantly increased the pH of soil and pore water, and decreased the DTPA-extractable Cd concentration in soil, but not the Cd concentration in pore water. Furthermore, the DTPA-extractable Pb concentration in rhizosphere soil was not significantly influenced by oyster shell addition. Application of oyster shell reduced the Pb concentration in pore water and Pb uptake by both cultivars, but excessive application (12 g kg-1) resulted in Cd accumulation in tissues for ZY18. Furthermore, oyster shell addition significantly increased the dissolved organic carbon, calcium, and magnesium concentrations in soil pore water, and decreased glutathione and phytochelatin levels in roots, all of which alleviated heavy metal toxicity and improved rice growth. These results demonstrate that amendment with the appropriate amount of oyster shell, combined with rice cultivar type, could simultaneously reduce Cd and Pb accumulation in rice grown in heavy metal-contaminated soil.

Understanding the mechanisms of zeolite in inhibiting Pb accumulation in different rice cultivars (Oryza sativa).

Zeolite is one of the potential passivating amendments for the immobilization of lead (Pb) in contaminated farmland soils. In this study, pot experiments were carried out to investigate the effects and the mechanisms of zeolite on Pb accumulation in two rice cultivars grown in a slightly Pb-contaminated soil. Results showed that Pb content in grains of Zheyou 18 (ZY-18) decreased by the addition of 6 g zeolite kg-1 soil (E6), which can be attributed to the reduction in soil Pb availability, dissolved organic carbon (DOC), water-soluble iron (Fe) and manganese (Mn), and the transfer factor from soil to grain (TFsoil-grain). These reductions were mainly resulting from the significant increase in soil pH, glutathione (GSH), phytochelatins (PCs), and non-protein (NPT) content in rice root, and the decrease in soil redox potential (Eh), due to zeolite addition. Pb content in brown rice of DL-5 was not significantly affected with E6 treatment, whereas it was raised by applying 12 g zeolite kg-1 soil (E12). The increase of Pb content of Donglian 5 (DL-5) grains with E12 treatment can be attributed to more Pb uptake by the root, higher Pb transfer factors (TFs) between various parts of rice, and significant decrease in GSH, PCs, and NPT contents in the root. It is concluded that a suitable rate of zeolite addition can immobilize Pb in slightly Pb-contaminated acidic soil. However, the final immobilization effect also depends on rice cultivars.

Complex ecological and socioeconomic impacts on medicinal plant diversity.

Medicinal plant diversity (MPD) is an important component of plant diversity. Over-collection based on medicinal and economic value has the potential to damage the stability of the regional ecosystem. It is important to understand the current distribution of MPD and the factors influencing it. However, it is still unclear whether environmental and socioeconomic conditions have an impact on their distribution. We selected the Inner Mongolia as a representative study area which covers a wide area, accounting for 12.29% of China's national land area and 0.79% of the world's land area. At the same time, the region is a long-standing traditional medicinal area for Mongolians in China. Therefore, the region is significantly influenced by changes in environmental factors and socio-economic factors. We used 9-years field survey of the distribution of medicinal plants in Inner Mongolia for assessing the distribution of MPD as influenced by environmental and socioeconomic activities by combining spatial analyses, species distribution models, and generalized additive models. The results from the spatial analysis show that the western region of Inner Mongolia is the main cold spot area of the MPD, and the central-eastern and northeastern regions of Inner Mongolia are the main hot spot areas of the MPD. At the same time, the distribution of cold spots and hot spots of MPD is more obvious at large spatial scales, and with the refinement of spatial scales, the cold spots in scattered areas are gradually revealed, which is indicative for the conservation and development of MPD at different spatial scales. Under the future climate change of shared socioeconomic pathways (SSP), areas with high habitat suitability for medicinal plants remain mainly dominated by the Yellow River, Yin Mountains, and Greater Khingan Range. Notably, the SSP245 development pathway remains the most significant concern in either long- or short-term development. The nonlinear relationship between the driving factors of MPD at different spatial scales shows that temperature, precipitation and socioeconomic development do have complex effects on MPD. The presence of a certain temperature, altitude, and precipitation range has an optimal facilitation effect on MPD, rather than a single facilitation effect. This complex nonlinear correlation provides a reference for further studies on plant diversity and sustainable development and management. In this study, the spatial distribution of medicinal plant resources and the extent to which they are driven by ecological and socioeconomic factors were analyzed through a macroscopic approach. This provides a reference for larger-scale studies on the environmental and socioeconomic influences on the distribution of plant resources.

Organic fertilizer amendment increases methylmercury accumulation in rice plants.

Rice grains are a methylmercury (MeHg) intake route for humans, especially in certain mercury (Hg)-contaminated areas. For rice plant growth, animal manure is commonly used as an organic fertilizer; however, its role in the formation of MeHg in paddy soils remains poorly understood. The aims of this study were thus to explore 1) the effect of chicken manure (CH) and cow manure (CO) addition on the production of soil MeHg and the accumulation of MeHg in rice plants and 2) the mechanism by which CH and CO addition affect the bioaccumulation of MeHg in grains. A pot experiment with different levels of CH and CO was carried out with newly deposited Hg-contaminated paddy soil. Two microcosm experiments were performed to explore the associated mechanisms. The results of the pot experiment showed that 0.1-1% CH and CO addition promoted the biomass of rice plants by 10-23% and increased the soil MeHg concentration by 34-143%, which exhibited a significant positive correlation with brown rice MeHg content. Organic fertilizer addition significantly increased MeHg bioaccumulation in rice plants and the ratio of MeHg to total Hg (THg) in brown rice. Organic fertilizer also increased the abundance of microbial methylators. The results of the microcosm experiments showed that organic fertilizer addition enhanced dissolved THg concentrations in soil and consequently increased the soil MeHg concentration. These results suggested that applying organic fertilizer to newly deposited Hg-contaminated soil may increase MeHg accumulation in grains due to enhanced Hg release and microbial methylator activity, leading to environmental health concerns.

Evidence for molecular antagonistic mechanism between mercury and selenium in rice (Oryza sativa L.): A combined study using 1, 2-dimensional electrophoresis and SR-XRF techniques.

Mercury (Hg) is a hazardous chemical in the environment and can accumulate in the food chain. Selenium (Se) is a necessary element for human health and has antagonistic effects on Hg toxicity. In this work, we investigated the effect of Se on Hg containing and Hg-responsive proteins in rice using 1, 2-dimensional electrophoresis combined with SR-XRF techniques. Two weeks old rice seedlings were exposed to Hg and/or Se compounds. After 21days proteins in the rice roots were separated by electrophoresis and their metal contents were determined by X-ray fluorescence to identify Hg and Se responsive biomolecules. The results show that under Hg stress alone Hg is bound to proteins with molecular weights of 15-25kDa. With the addition of Se, a new Hg-containing protein band in the 55-70kDa range was also found, while the content of Hg in the 15-25kDa proteins decreased. Ten and nine new protein spots were identified after adding Se to inorganic Hg and methylmercury exposed roots, respectively. Adding Se regulates the abundance of proteins associated with carbohydrate and energy metabolism, stress response, cell cycle, and DNA replication indicating that these proteins mediate the antagonism of Se against Hg toxicity. This study helps us to better understand the molecular mechanism of Hg tolerance as well as the molecular antagonism between Hg and Se in rice plants.

Ca-containing amendments to reduce the absorption and translocation of Pb in rice plants.

The influence of three Ca-containing amendments (dolomite, slaked lime, and limestone) on soil water soluble Pb (Pb-w) levels, Pb accumulation by two rice plants (TJ-8, japonica and II-3301, indica), and the factors affecting Pb-w were investigated. Pot experiment was performed under waterlogged conditions using Pb-contaminated soil collected from an agricultural field near a mine. It was found that the soil amendments significantly reduced Pb content in the rice plants in the order dolomite > slaked lime > limestone, irrespective of rice cultivar. The Pb content of brown rice with the added soil amendments was lower than that of the recommended limit (0.2 mg kg-1, GB2762-2017) except for cultivar II-3301 with slaked lime. There was a significant positive correlation between the Pb content of the roots, stems, leaves, and grains and the soil Pb-w levels. The amendments reduced soil Eh, Fe, and Mn concentrations in the pore water and increased soil pH. The total organic carbon (TOC) in the pore water significantly decreased for II-3301 but not for TJ-8 at the ripening stage after addition of the amendments. Among soil Eh, pH, TOC, Fe, and Mn in the pore water, Fe and Mn were the most influential in lowering soil Pb-w levels. The amendments inhibited the formation of iron plaques on the root surface and reduced Pb adsorption. The Pb content of the roots was positively correlated with that in iron plaque. These findings are significant as they imply that the application of Ca-containing amendments in Pb-contaminated paddy soils near mines is an effective approach for in situ immobilization of Pb and reduction in Pb levels in the edible parts of crops.

Influence of sulfur on the accumulation of mercury in rice plant (Oryza sativa L.) growing in mercury contaminated soils.

Sulfur (S) is an essential element for plant growth and its biogeochemical cycling is strongly linked to the species of heavy metals in soil. In this work, the effects of S (sulfate and elemental sulfur) treatment on the accumulation, distribution and chemical forms of Hg in rice growing in Hg contaminated soil were investigated. It was found that S could promote the formation of iron plaque on the root surface and decrease total mercury (T-Hg) and methylmercury (MeHg) accumulation in rice grains, straw, and roots. Hg in the root was dominated in the form of RS-Hg-SR. Sulfate treatment increased the percentage of RS-Hg-SR to T-Hg in the rice root and changed the Hg species in soil. The dominant Hg species (70%) in soil was organic substance bound fractions. Sulfur treatment decreased Hg motility in the rhizosphere soils by promoting the conversion of RS-Hg-SR to HgS. This study is significant since it suggests that low dose sulfur treatment in Hg-containing water irrigated soil can decrease both T-Hg and MeHg accumulation in rice via inactivating Hg in the soil and promoting the formation of iron plaque in rice root, which may reduce health risk for people consuming those crops.

[Construction and identification of HSV-1 vector vaccine carrying HIV-1 antigen].

To construct an HSV-1 vector vaccine carrying HIV-1 antigens, HIV-1 gp160, gag, protease and the expression elements were chained together, and then inserted into the internal inverted repeat sequence region of HSV-1 by bacterial artificial chromosome technology. Firstly, HIV-1 gp160 (including type B and C), gag and protease genes were cloned into pcDNA3 in series to generate the pcDNA/gBgp and pcDNA/gCgp, then the recombinant plasmids were transfected into 293FT cells, and HIV-1 antigen was detected from transfected cells by Western blotting. Then the expression cassettes from pcDNA/gBgp and pcDNA/gCgp, comprising HIV-1 antigen genes and expression elements, were cloned into pKO5/BN to generate the shuttle plasmids pKO5/BN/gBgp and pKO5/BN/gCgp. The shuttle plasmids were electroporated into E. coli cells that harbor an HSV-BAC, the recombinant bacteria were screened, and the recombinant DNA was extracted and transfected into Vero cells. The recombinant virus was purified through picking plaques, the virus' DNAs were identified by Southern blotting; HIV-1 antigen was detected from the recombinant HSV-1 infected cells by Western blotting, and the virus' replication competent was analyzed. As the results, gp160 and gag proteins were detected from 293FT cells transfected with pcDNA/gBgp and pcDNA/gCgp by Western blotting. The recombinant bacteria were generated from the E. coli electroporated with pKO5/BN/gBgp or pKO5/BN/gCgp. The recombinant HSV was purified from the Vero cells transfected with the recombinant DNA, the unique DNA fragment was detected from the genome of recombination HSV by Southern blotting; gp120 and gp41 were detected from the infected cells by Western blotting, and the recombinant HSV retained replication competent in mammalian cells. The results indicate that the recombinant HSV carrying HIV-1 gp160, gag and protease genes was generated, the virus retains replication competent in mammalian cells, and could be used as a replicated viral vector vaccine.