Hypoxia-regulated microRNAs in human cancer.

Hypoxia plays an important role in the tumor microenvironment by allowing the development and maintenance of cancer cells, but the regulatory mechanisms by which tumor cells adapt to hypoxic conditions are not yet well understood. MicroRNAs are recognized as a new class of master regulators that control gene expression and are responsible for many normal and pathological cellular processes. Studies have shown that hypoxia inducible factor 1 (HIF1) regulates a panel of microRNAs, whereas some of microRNAs target HIF1. The interaction between microRNAs and HIF1 can account for many vital events relevant to tumorigenesis, such as angiogenesis, metabolism, apoptosis, cell cycle regulation, proliferation, metastasis, and resistance to anticancer therapy. This review will summarize recent findings on the roles of hypoxia and microRNAs in human cancer and illustrate the machinery by which microRNAs interact with hypoxia in tumor cells. It is expected to update our knowledge about the regulatory roles of microRNAs in regulating tumor microenvironments and thus benefit the development of new anticancer drugs.

SOX10 promotes the malignant biological behavior of basal-like breast cancer cells by regulating EMT process.

Background: The diagnostic utility of SRY-box transcription factor 10 (SOX10) expression in basal-like breast cancer (BLBC) has been reported previously. However, the effect of SOX10 on the malignancy of BLBC cells and the underlying molecular mechanisms remain unelucidated. Here, we investigate the regulatory mechanisms and roles of SOX10 in BLBC progression. Methods: Sequencing data from patients with BLBC were extracted from the Cancer Genome Atlas database to determine the transcriptomic levels of SOX10 across breast cancer subtypes. Subsequently, the bioinformatics relevance of SOX10 in BLBC was investigated. Immunohistochemical assays were used to corroborate the protein expression of SOX10 in clinicopathological specimens (human breast cancer paraffin tissues). RNA interference was used to downregulate SOX10 expression, and the efficiency of interference was evaluated using quantitative PCR. The expression levels of molecules related to the epithelial-mesenchymal transition (EMT) pathway were determined by western blotting. Various assays, such as transwell, colony formation, and flow apoptosis assays, were conducted to assess the malignancy of BLBC cells (MDA-MB-231). Results: Bioinformatics analyses revealed the differential expression of SOX10 in various breast cancer subtypes. An association between SOX10 and immune checkpoint expression was observed in BLBC. Additionally, immune correlation analysis indicated a positive relationship between SOX10 expression and effector immune cells. SOX10 was identified as a potential immunotherapeutic target. Juxtaposed with non-basal-like breast cancer (N-BLBC) and breast adenosis, immunohistochemical analysis revealed the upregulated expression of SOX10 in BLBC, indicating its potential diagnostic significance. Single-gene functional enrichment analysis indicated that SOX10 is associated with EMT and the tumor inflammatory index. Experimental outcomes from cellular assays suggested that the downregulation of SOX10 inhibited multiple malignancy-associated behaviors in MDA-MB-231 cells, specifically affecting the EMT process, migration, invasion, proliferation, clone formation, and anti-apoptotic activities. Conclusions: We concluded that SOX10 contributes to the malignancy of BLBC cells by modulating the EMT pathway. Moreover, we observed a notable correlation between SOX10 expression and immune responses, indicating the potential significance of SOX10 in immunotherapy.

Photocatalytic oxidation and removal of arsenite by titanium dioxide supported on granular activated carbon.

Arsenic contamination in drinking water is a worldwide concern. Photocatalysis can rapidly oxidize arsenite, i.e. As(III), to less labile arsenate, i.e. As(V), which then can be removed by adsorption on to various adsorbents. This study investigated the photocatalytic oxidation of arsenite in aqueous solution by granular activated carbon supporting a titanium dioxide photocatalyst (GAC-TiO2). The effects of photocatalyst dosage, solution pH values, initial concentration of As(III) and co-anions (SO4(2-), PO4(3-), SiO3(2-) and Cl-) on the oxidation of As(III) were studied. The photocatalytic oxidation of As(III) took place in minutes and followed first-order kinetics. The presence of phosphate and silicate significantly decreased As(III) oxidation, while the effect of sulphate, chloride was insignificant. The oxidation efficiency of As(III) was observed to increase with increasing pH. The results suggest that the supported photocatalyst developed in this study is an ideal candidate for pre-oxidation treatment of arsenic-contaminated water.

[Association between the synovial expression of cyclic citrullinated peptide and susceptibility variants of HLA-DRB1 shared epitope alleles and PADI 4 gene single nucleotide polymorphisms in patients with rheumatoid arthritis].

OBJECTIVE: To analyze the association between the synovial expression of cyclic citrullinated peptide (CCP) and susceptibility variants of HLA-DRB1 shared epitope (SE) alleles and/or peptidylarginine deiminase 4 (PADI4) gene single nucleotide polymorphisms (SNP) in patients with rheumatoid arthritis (RA). METHODS: From October 2008 to December 2011, 53 RA patients and 42 controls were enrolled. The expression of CCP in RA synovial tissues was detected by immunohistochemical assay with 6×His tagged anti-CCP single chain fragment V (ScFv) antibodies generated by pHEN2 phagemid recombinant antibodies display system. PADI4 SNP was genotyped by reverse transcription cDNA sequencing and heterozygote was DNA haplotype was mapped by TA clone sequencing. HLA-DRB1 SE alleles were analyzed by sequence specific primer-polymerase chain reaction (SSP-PCR). RESULTS: The prevalence of synovial CCP expression was significantly different between RA group and the control (76.9% and 11.4% respectively, P < 0.01). The frequencies of 2 SNPs (PADI4_89 G+ and PADI4_104 T+) varied significantly between the groups(P < 0.05). Compared with the major haplotypes, only these two minor alleles were associated with the increased RA susceptibility (OR = 3.67 and 2.53, P < 0.05). SE+ alleles was strongly associated with RA susceptibility (OR = 5.57, P < 0.01). The synovial expression of CCP in RA was strongly associated with SE+ alleles, only 2 minor SNPs (PADI4_89 G+ and PADI4_104T+) and the combination. Serum anti-CCP titers were significantly associated with SE+ alleles, PADI4_104T+, SE+/PADI4_89 G+ and SE+/PADI4_104T+ haplotype. CONCLUSION: The synovial expression of CCP and the generation of anti-CCP antibodies are strongly associated with SE alleles and/or certain PADI4 gene SNP in RA.

Digestive solubilization of Cd in highly-contaminated sediment by marine deposit feeders: The roles of intestinal surfactants in Cd mobilization and Re-Adsorption processes.

Marine deposit feeders are of ecological significance in transferring sedimentary Cd along aquatic food chains. A key process for this transfer is these organisms' dietary uptake of Cd via solubilization of Cd present in ingested contaminated sediment. To better understand the bioavailability of sedimentary Cd to deposit feeders, the present study used in vitro extraction experiments to explore the contribution of different digestive agents (proteins, amino acids and surfactants) to the solubilization of Cd from sediment collected in a highly-contaminated Chinese bay. This was done for various commercially-available mimetic digestive agents (the protein BSA, a mixture of amino acids, and the surfactants rhamnolipid and SDS), and for proteins and surfactants collected from the gut juice of a sipunculan worm. The Cd mobilization capacity of BSA was significantly higher than that of the amino acids and the commercial surfactants. In the presence of BSA, > 70% of the released Cd became associated with this protein. In contrast, the digestive proteins from the sipunculan had a lower Cd mobilization capacity than was the case for the other digestive agents and the majority of the released Cd (∼80%) was associated with small molecular weight fractions. The differences in Cd mobilization between the BSA and the digestive proteins were attributed to differences in their sediment-adsorption tendencies and their Cd-complexing capacities. While the digestive surfactants had minor effects on the release of sedimentary Cd, they significantly enhanced Cd mobilization by the digestive proteins when both were present simultaneously. Our results suggest that the characteristics of proteins should be considered when using commercially-available mimetic digestive agents to explore Cd bioavailability in sediments. Furthermore, digestive surfactants seem to have important effects on the solubilization of Cd during gut passage by reducing the adsorption of the digestive proteins to the sediments.

Paeoniflorin Inhibits Migration- and Invasion-Promoting Capacities of Gastric Cancer Associated Fibroblasts.

OBJECTIVE: To investigate the inhibitory effects of paeoniflorin on migration- and invasion-promoting capacities of gastric cancer associated fibroblasts (GCAFs) and to explore the molecular mechanism underlying the effects. METHODS: Paired gastric normal fifbroblast (GNF) and GCAF cultures were established from resected tissues. GCAFs were treated with control medium, or 2.5, 5 or 10 µg/mL paeoniflorin. Conditioned media were prepared from GNFs, GCAFs, control-treated GCAFs and paeoniflorin-treated GCAFs, and used to culture AGS human gastric cancer cells. The migration and invasion capacities of AGS cells were determined with wound healing test and transwell invasion assay, respectively. The interleukin 6 (IL-6) mRNA and microRNA-149 expression in GCAFs were detected by reverse transcription-quantitative polymerase chain reaction. The IL-6 protein expression and secretion by GCAFs were measured with Western blot and enzyme-linked immunosorbent assay analysis, respectively. The protein levels of phosphorylated signal transducer and activator of transcription 3 (STAT3), matrix metalloproteinase (MMP) and MMP9 in AGS cells were examined by Western blot. RESULTS: GCAFs displayed enhanced capacities to induce AGS cell migration and invasion as compared with GNFs. Paeoniflorin treatment significantly inhibited the migration- and invasion-promoting capacities of GCAFs (P<0.05). GCAFs produced and secreted more IL-6 into the conditioned medium than GNFs, leading to over-activation of STAT3-MMP signaling in AGS cells. Paeoniflorin suppressed IL-6 production and secretion by up-regulating microRNA149 expression in GCAFs, and subsequently prevented GCAFs from activating IL-6-STAT3-MMP signaling of AGS cells. CONCLUSIONS: Paeoniflorin inhibits the migration- and invasion-promoting capacities of GCAFs by targeting microRNA-149 and IL-6. Paeoniflorin is potentially a novel therapeutic agent against cancer microenvironment.

Therapeutic effect of tripterine on adjuvant arthritis in rats.

AIMS OF THE STUDY: Tripterygium wilfordii Hoog f., a perennial vine, is used in traditional Chinese medicine for treatment of rheumatoid arthritis. This study was to determine whether tripterine, isolated from Tripterygium wilfordii Hoog f., had therapeutic effects on adjuvant arthritis. MATERIALS AND METHODS: Adjuvant arthritis (AA) was induced in rats on day 0. Tripterine 5, 10 and 20 mg kg(-1)day(-1), or prednisone 10 mg kg(-1)day(-1) was given to rats intragastrically from day 19 to day 24. RESULTS: Tripterine significantly inhibited paw swelling and bone destruction in AA rats. Serum level of IgG anti-Mycobacterium tuberculosis antibodies and delayed-type hypersensitivity (DTH) induced by Mycobacterium tuberculosis were also decreased by tripterine. The effects of tripterine were associated with decreased interleukin-1beta (IL-1beta) mRNA expression in ankle joint synovial membrane and tumor necrosis factor-alpha (TNF-alpha) mRNA expression in homogenized paws from adjuvant-induced arthritic rats. CONCLUSIONS: These findings suggested that tripterine had a therapeutic effect on adjuvant arthritis.

RRS1 silencing suppresses colorectal cancer cell proliferation and tumorigenesis by inhibiting G2/M progression and angiogenesis.

Colorectal cancer (CRC) is one of the most common malignancies worldwide. Ribosome biogenesis regulatory protein homolog (RRS1) is an essential factor involved in ribosome biogenesis, while its role in CRC remains largely unclear. Here, we found that RRS1 expression was significantly higher in CRC tissues compared with adjacent normal tissues. RRS1 High expression also predicted poor overall survival of CRC patients. Knockdown of RRS1 induced the G2/M cell cycle arrest, apoptosis and suppressed the proliferation of RKO and HCT-116 CRC cells. Furthermore, angiogenesis was also reduced in CRC cells after RRS1 knockdown. In addition, suppression of RRS1 blunted the tumor formation of CRC cells in nude mice. At the molecular level, silencing of RRS1 decreased the expression of M-phase inducer phosphatase 3 (CDC25C), Cyclin-dependent kinase 1 (CDK1), antigen KI-67 (KI67) and increased the protein level of cyclin-dependent kinase inhibitor 1 (CDKN1A) and tumor suppressor p53 (p53). Taken together, our findings provide evidence that RRS1 may promote the development of colon cancer. Therefore, targeting RRS1 may be a promising therapeutic strategy for CRC patients.

Beneficial effect of tripterine on systemic lupus erythematosus induced by active chromatin in BALB/c mice.

The aim of this study was to determine whether tripterine, isolated from Tripterygium wilfordii Hoog f. in China, had beneficial effects on experimental systemic lupus erythematosus induced by active chromatin in BALB/c mice. BALB/c mice were immunized with active chromatin isolated from concanavalin A-activated syngenetic spleno-lymphocytes on day 0. Tripterine 6 or 12 mg kg(-1) day(-1), or prednisone 5 mg kg(-1) day(-1) was given to BALB/c mice intragastrically from day 35 to day 50. Treatment with tripterine 12 mg kg(-1) day(-1) for 15 days protected renal from glomerular injury with a concomitant reduction of serum autoantibodies and total immunoglobulin G (IgG) also with a improvement of splenocyte proliferation stimulated with concanavalin A and lipopolysaccharide. The effects were associated with reduced interleukin-10 production and serum nitric oxide (NO) level but not interferon-gamma compared with vehicle-treated control group. Tripterine 6 mg kg(-1) day(-1) had no significant protective effect against glomerular injury. It inhibited autoantibodies and interleukin-10 production but had no effect on splenocyte proliferation, serum NO level, and interferon-gamma production. These findings suggested that tripterine had a beneficial effect on systemic lupus erythematosus induced by active chromatin in BALB/c mice.

[XAS Analysis upon Dissolved Species of Orpiment in Anoxic Environment].

The orpiment[As2S3(s)] is an important secondary mineral in the geochemical process of arsenic in the environment. The study upon orpiment dissolution is important to investigate the migration and transformation of arsenic in the environment. The environmental pH and sulfur content have vital influence on species changing and stability of arsenic species in orpiment. Here we analyzed the stable arsenic species of anoxic orpiment dissolution in sulfidic and the absence of sulfide solutions at neutral condition with simulation test via X-ray absorption near edge spectroscopy(XANES) and extended X-ray absorption fine structure(EXAFS). The results showed that orpiment dissolution contained a mixture of arsenite and thioarsenite species at neutral condition, and arsenic species in sulfidic solutions is mainly thioarsenic, while arsenic species in the absence of sulfide solutions is oxythioarsenic. The results of Linear Combination of Fits showed that arsenic species were arsenite (88. 2%) and thioarsenite(11. 8%) in sulfidic solutions, and there were arsenite (56. 3%) and thioarsenite(43. 7%) in the absence of sulfide solutions. Our results confirmed that the formation of arsenite was related to the total sulfur to total arsenic ratios, and the form of thioarsenite species could be enriched by increasing of the total sulfur to total arsenic ratio.

Roles of Signaling Pathways in the Epithelial-Mesenchymal Transition in Cancer.

The epithelial-mesenchymal transition (EMT) is a cellular process though which an epithelial phenotype can be converted into a phenotype of mesenchymal cells. Under physiological conditions EMT is important for embryogenesis, organ development, wound repair and tissue remodeling. However, EMT may also be activated under pathologic conditions, especially in carcinogenesis and metastatic progression. Major signaling pathways involved in EMT include transforming growth factor ß(TGF-ß), Wnt, Notch, Hedgehog and other signaling pathways. These pathways are related to several transcription factors, including Twist, Smads and zinc finger proteins snail and slug. These interact with each other to provide crosstalk between the relevant signaling pathways. This review lays emphasis on studying the relationship between EMT and signaling pathways in carcinogenesis and metastatic progression.

[Chemical extraction of arsenic co-precipitated with amorphous Fe (OH)3 and Fe3O4].

The mobility and bioavailability of As combining with amorphous Fe oxides is vulnerable to the environment. In order to figure out the specific effects of ageing time, Fe/As molar ratio and extractant-to-solid ratio on As extraction procedure, we chose 1 mol x L(-1) hydrochloride acid and 0.2 mol x L(-1) ammonium oxalate/oxalic acid as extractants to extract synthetic Fe (OH)3-As and Fe3O4-As co-precipitates. The results showed that: (1) During the extraction of Fe(OH) 3-As and Fe3O4-As co-precipitates by 1 mol x L(-1) hydrochloride acid, extractant-to-solid ratio should be 50 and 200, respectively; while extracted by 0.2 mol x L(-1) ammonium oxalate/oxalic acid, the molar ratio of C2O4(2-) to Fe in Fe(OH)3 and Fe3O4 solid phases should be 4 and 2.5, (2) The extraction time conducted by hydrochloride acid and ammonium oxalate/oxalic acid should be within 2 hours. (3) The Fe-to-As molar ratio and ageing at room temperature had a little influence on the extraction of Fe(OH)3-As co-precipitation, but significantly influenced on Fe3O4-As co-precipitation. With increase of the Fe/As molar ratio and extension of the ageing time, the Fe3O4-As co-precipitate became more difficult to be dissolved. (4) It was worth noting that, As would be re-adsorpted by the insoluble solid phase during the extraction by hydrochloride acid and ammonium oxalate/oxalic acid. So the inaccurate measurement would emerge during the extraction of As combining with amorphous Fe oxides.

Upregulation of microRNA-224 is associated with aggressive progression and poor prognosis in human cervical cancer.

OBJECTIVE: Accumulating evidence for differential expression of microRNA-224 (miR-224) in various types of human cancer suggests that it may be play a crucial role in tumor biology. The previous microarray detection also shown that miR-224 was one of miRNAs with significant upregulation in cervical cancer tissues relative to adjacent normal tissues. However, little is known about the function of miR-224 in human cervical cancer. The aim of this study was to investigate the clinical significance of miR-224 expression in cervical cancer. METHODS: MiR-224 expression in 126 pairs of fresh human cervical cancer and adjacent normal tissues was measured by real-time quantitative RT-PCR assay. RESULTS: miR-224 expression was significantly upregulated in cervical cancer tissues when compared with corresponding adjacent normal tissues (P<0.001). It was also significantly higher in the cancerous tissues of patients with advanced FIGO stage cervical cancer than those with early FIGO stage (P=0.02). In addition, miR-224 was expressed at significantly higher levels in lymph node metastasis-positive patients than in lymph node metastasis-negative patients (P=0.008). Moreover, we found that lesser differentiated tumors expressed higher miR-224 (P=0.03). Finally, there were sufficient evidence to confirm its value in the status of vascular invasion (P=0.01) and human papillomavirus (HPV) infection (P=0.02) in cervical cancer. More importantly, Kaplan-Meier analysis showed that cervical cancer patients with high miR-224 expression tend to have shorter overall survival. In multivariate analysis stratified for known prognostic variables, miR-224 was identified as an independent prognostic marker. CONCLUSION: Our data indicated that miR-224 upregulation was associated with aggressive progression and poor prognosis in cervical cancer. MiR-224 was identified for the first time as an independent marker for predicting the clinical outcome of cervical cancer patients. VIRTUAL SLIDES: The virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/2170449349527493.

[Speciation transformation and behavior of arsenic in soils under anoxic conditions].

The soil of 0-100 cm depth was collected from the wastewater-irrigated farmland in Zhangshi, Shenyang and was amended with low concentration of arsenic. Microbial-mediated speciation transformation and environmental behavior of arsenic were investigated with and without addition of sulfate. The results showed that without addition of sulfate, arsenate was significantly reduced and released into soil solution after eight days of anaerobic incubation. Above 70% of arsenic presented as arsenite. More arsenic was released from the soil of 20-40 cm depth with arsenite and total arsenicconcentration of 892.8 microg x L(-1) and 1 240.6 microg x L(-1) respectively. Compared with abiotic control, the amount of arsenic dissolved in hydrochloric acid decreased greatly in each layer of soil, moreover, almost all of arsenic was reduced to arsenite. Ferric iron was also significantly reduced to ferrous and released into soil solution simultaneously. The concentration of ferrous iron in soil solution was above 40 mg x L(-1) in solution and was 9.0-13.4 g x kg(-1) in soil solid. Above 50% of the iron dissolved in hydrochloric acid was presented as ferrous. This indicates that microbial reduction leads to reductive dissolution of iron oxides and transformation of mineral configuration in soil solid. The release of arsenic and iron was notably suppressed after addition of 10 mmol x L(-1) sulfate, with the concentration reduced by 50%. The amount of HCl-dissolvable arsenic in soil solid decreased by 50%, compared to the treatment without sulfate addition, which probably due to precipitation of arsenic sulfide. It is obvious that microbial reduction leads to reduction and release of arsenic when sulfate is absent. In the presence of sulfate, microbes may transform mobile arsenic into more stable species. Formation of arsenic sulfide mineral was probably the mechanism for arsenic fixation in soil by microbes.

Expression patterns of ER, HER2, and NM23-H1 in breast cancer patients with different menopausal status: correlations with metastasis.

OBJECTIVE: This study was designed to analyze expression patterns of estrogen receptor (ER), human epidermal growth factor receptor-2 (HER2/ERBB2), and nonmetastatic protein 23 (NM23-H1/NME1) proteins in patients with invasive ductal carcinoma and different menopausal status to identify their relationships with axillary lymph node metastasis. MATERIALS AND METHODS: 213 pre-menopausal and 177 post-menopausal women diagnosed with invasive ductal carcinoma were evaluated for ER, HER2, and NM23-H1 protein expression by immunohistochemistry. When HER2 immunoreactivity was equivocal (category 2+), specimens were confirmed by fluorescence in situ hybridization. RESULTS: ER expression showed no correlation with menopausal status or lymph node metastasis (each p > 0.05). However, expression of ER was associated with negative expression of HER2 (r = -0.214, p < 0.05) and positive expression of NM23-H1 (r = 0.137, p < 0.05) in the pre-menopausal group. Over-expression of HER2 was correlated with menopausal status (r = -0.107, p < 0.05) and lymph node metastasis in the ER-negative post-menopausal group (r = 0.222, p < 0.05). NM23-H1 was associated with less lymph node metastasis in the ER-positive pre-menopausal group (r = -0.237, p < 0.05). CONCLUSION: Our results indicated that expression patterns of ER, NM23-H1, and HER2 in primary breast cancer lesions warn that cells might have metastatic potential, which could assist clinicians to provide a more accurate prognosis and tailor therapeutic management for individual patients.

[Influence of speciation on the bioavailability of particle-bound cadmium in sediments].

In the present work, the impact of speciation on the bioavailability of cadmium in sediments was investigated. Bioaccumulation of cadmium adsorbed on various (hydr)oxide minerals, i.e. ferric hydroxide, aluminum hydroxide and manganese dioxide, by bivalve Meretrix meretrix Linnaeus, was measured using a suspending system. The results showed that the bioavailability of cadmium was significantly different for different minerals. At Cd concentration of 70 mg/kg, the accumulation of Cd by clams in Cd-Fe(OH)3 and Cd-Al(OH)3 system was not detectable after 22 days of exposure. In comparison, the clams absorbed appreciable amount of Cd from 70 mg/kg of Cd-MnO2 system. An average uptake rate of (0.0094 +/- 0.0010) microg/(g x d) for 70 mg/kg Cd-MnO2 was obtained by linear fitting curve (r2 = 0.853 9, p < 0.000 1). When Cd concentration was increased to 140 mg/kg, bioaccumulation of Cd from Cd-Fe(OH)3 system was still not observed, while for the clams cultivated in Cd-Al(OH)3 and Cd-MnO2 systems, Cd was apparently assimilated in the body of the animals. The uptake rates were determined to be (0.0166 +/- 0.0017) microg/(g x d) for Cd-Al(OH)3 and (0.024 8 +/- 0.0017) microg/(g x d) for Cd-MnO2. Generally, The bioaccumulation sequence of the Cd-(hydr) oxides is Cd-MnO2 > Cd-Al (OH)3 > Cd-Fe (OH)3. The type of minerals determines both assimilation efficiency and ingestion rate, consequently controls the bioaccumulation of adsorbed cadmium.

[Bioavailability of cadmium associated with oxides in sediment: effects of species of mineral, association form and aging on bioavailability].

The bioavailability of heavy metals in sediments is largely controlled by their speciation. Effects of different Cd speciation associated with metal hydroxide on Cd bioavailability were studied. Iron and aluminum hydroxides were chosen as representatives of the oxides commonly present in sediments. In cultivar system, Hoagland solution was used as nutrition supply, and metal hydroxide associated with Cd as the only source of contamination and Phragmites australis was induced to study Cd bioaccumulation. After 13 d cultivation, Cd was uptaken and accumulated in P. australis, with different bioaccumulation from 9.1 to 37.8 mg x kg(-1) in root; and 0 to 10.0 mg x kg(-1) in shoot. Hereinto, the P. australis cultivated in Fe0.5Al0.5(OH)3 medium was found to have accumulated the largest amount of Cd in root, followed by those in Fe(OH)3 and aged Fe0.5Al0.5(OH)3, the lowest root concentration of Cd was observed in the plants cultivated in aged Fe(OH)3. Desorption order of Cd by organic acid was consistent with the Cd accumulation in P. australis. Thus, coprecipitation treatment decreases the bioavailability of Cd; association of aluminum hydroxide with Cd is poor due to its physicochemical property; aging treatment significantly restrict the accumulation of adsorbed Cd; desorption by organic acid verify the discrepancy in bioavailability of different speciation of Cd.

[Removal of arsenite from drinking water by activated carbon supported nano zero-valent iron].

Nano zero-valent iron was loaded onto activated carbon by deoxidizing Fe2+ in aqueous solution and approximately 8.2% (wt) of iron was loaded it. The size of the needle-shaped iron particles in the pores of carbon was (30-500) x (1 000-3 000) nm. The adsorption capacity for arsenic was approximately 1.997 mg/g activated carbon supported nano zero-valent iron (NZVI/AC) in the 2 mg/L As(III) solution at pH 6.5 and (25 +/- 2) degrees C. The uptake of arsenic by NZVI/AC was rapid in the first 12 h (94.3%) and equilibrium was achieved at 72 h (99.86%). As(III) was partly oxidized by the absorbent in the process of absorption. The presence of phosphate and silicate ions significantly decreased arsenic removal rate while the effect of other common ions such as sulfate, carbonate and oxalate was insignificant. NZVI/AC was effectively regenerated after adsorption of arsenic when elution was applied with 0.1 mol/L NaOH solution. The results suggest that NZVI/AC is an ideal candidate for the treatment of arsenic contaminated drinking water.

[Microbial reduction and mobilization of adsorbed arsenate on ferric/aluminum hydroxides].

Although the mechanisms of arsenic release into groundwater remain poorly characterized, microbial reduction of As (V) adsorbed on the surface of iron oxides and the reductive dissolution of iron oxides are generally considered to play a key role in the mobilization of arsenic. We investigated the impact of bacterial reduction of adsorbed As (V) on a Al:Fe (1:0, 1:1, 0:1) hydroxides on arsenic mobilization using the mixed bacterial culture. After inoculation, the increase of dissolved As (III) concentration was observed, whereas As (V) was negligible in aqueous phase. Arenic release for the Al:Fe (1:0, 1:1, 0:1) hydroxides systems was 60 microg/L, 1.3 mg/L and 7.8 mg/L respectively. On the contrary, neither reduction nor release of arsenic was observed in the uninoculated groups. Furthermore, the introduction of aluminium may be responsible for the release of arsenic owing to its weaker affinity to As (III). In addition, our results showed that Fe reduction occurred far later than arsenic reduction and mobilization and obvious increase was not observed even after Fe reduction occurred. It suggested that in natural systems, the biotic reduction of As (V) adsorbed on ferric oxides or Fe (III) may not the major cause of arsenic release in sediment or groundwater system as previous works proposed. The reduction of As (V) bound to aluminum oxides or other minerals may play a key role.