[Effect of prostate peripheral zones stromal cells on the proliferation of prostate cells by overexpression of LMO2 gene].

OBJECTIVE: To explore the biological effect of prostate peripheral zones (PZs) stromal cells on the proliferation of prostate cells by overexpression of LMO2 gene. METHODS: Genes expressional distinction of different prostate stromal cells was screened by gene expression arrays. To validate the microarray data, real time-polymerase chain reaction (RT-PCR), Western blotting analysis were used to check the over expression of LMO2 in PZs cells.To compare the effect of stromal cells which overexpressed LMO2 gene on in vitro proliferation ability of BPH-1 and PC3 cell lines, cell proliferation was measured by CCK-8 and EdU assay. Cytokines chip was used to screen expression of cytokines in WPMY-1-LMO2 conditioned medium. The changes of BPH-1 and PC3 proliferation associated proteins were assessed by Western blotting. RESULTS: A total of 512 genes were identified as markedly differentially expressed in stromal cells originated from different zones. Among these genes, LMO2 gene was overexpression in peripheral zones stromal cells, and confirmed by RT-PCR and Western blotting. Expression level of LMO2 gene was significantly up-regulated in peripheral zones stromal cells compared with transitional zones stromal cells, increased by 3.36 folds on average (P<0.01). The proliferation of both PC3 and BPH-1 were found increased and STAT3 phosphorylation and CCND1 expression were increased after cultured in conditioned medium from stromal cells which stably expressed LMO2. Cytokines chip found increased FGF-9 and IL-11 expression in the medium supernatant reserved from LMO2-overexpressed stromal cell line. CONCLUSIONS: Distinct gene expression exists among prostate stromal cells originated from different zones. LMO2 overexpressed stromal cells can induce prostate epithelial cell growth via paracrine of FGF-9, IL-11 or other cytokines.

[Anatomical study of the architecture of the cutaneous branch-chained blood vessels in the medial lower leg in adult].

Objective: To investigate the architecture of the cutaneous branch-chained blood vessels in the medial lower leg and provide the anatomical basis for design and clinical application of the cutaneous branch-chained flap from this region. Methods: The experimental research method was used. From March to May 2023, the anatomical study was conducted on the 5 voluntarily donated fresh adult (aged 50 to 70 years, all male) cadaveric specimens from Hangzhou Normal University School of Basic Medical Sciences. The fine anatomy under microscope was performed on each lower leg specimens of 5 corpses (1 lower leg specimen was conducted with digital radiography (DR) scan before fine anatomy), to observe, measure, and record the course of posterior tibial artery, quantity of perforator, the distance between the perforating point of each perforator and the medial condyle of tibia, the external diameter of posterior tibial artery perforator, the length of perforator pedicle, the horizontal distance between the posterior tibial artery perforator and the saphenous nerve, and the course of each perforator within superficial fascia after crossing the deep fascia and the distribution of the cutaneous branch-chains. The DR scan under the perfusion of barium sulfate was conducted in one lower leg specimen to observe the distribution of cutaneous branch-chained vascular network (hereinafter referred to as vascular chain) between perforators. Transparent skin specimen was made from one leg specimen after anatomy to observe the distribution of perforators and vascular chains between perforators. Results: In 5 lower leg specimens, the upper part of posterior tibial artery was located deep in soleus muscle, and the lower part was located between the medial edge of gastrocnemius muscle and flexor digitorum longus muscle. A total of 28 posterior tibial artery perforators were identified, with an average of 5.6 branches in each lower leg. The distance between the perforating point of perforator and the medial condyle of tibia ranged from 6.5 to 36.0 cm, mainly distributed at 22.0 (15.1, 28.1) cm from the medial condyle of tibia, in zones 3 to 6. The external diameters of perforators of posterior tibial arteries were 0.7-1.1 mm. The length of perforator pedicle was 1.0-4.5 cm, and the horizontal distance between the posterior tibial artery perforator and the saphenous nerve was 0.5-3.0 cm. The fine anatomy under microscope showed that the posterior tibial artery perforators had long upward and downward branches after crossing the deep fascia, and the ascending branches and descending branches were anastomosed longitudinally to form the nutrient cutaneous branch-chain in the medial lower leg. DR scan and transparent skin specimen both showed that longitudinal vascular chain was formed between the posterior tibial artery perforators, the transparent skin specimen also showed that longitudinal blood vessel chains included the direct connecting vessels in the adipose layer and the indirect connecting vessels in the subdermal layer. Conclusions: The cutaneous branch-chained vessels in the medial lower leg are constructed by posterior tibial artery perforators, direct connecting vessels, indirect connecting vessels, and traffic branches. The cutaneous branch-chained flap is reliable in terms of vascular anatomy, and can carry the saphenous nerve for partial restoration of its sensation, thus it is an ideal flap.

Selenium concentration and speciation in biofortified flour and bread: Retention of selenium during grain biofortification, processing and production of Se-enriched food.

The retention and speciation of selenium in flour and bread was determined following experimental applications of selenium fertilisers to a high-yielding UK wheat crop. Flour and bread were produced using standard commercial practices. Total selenium was measured using inductively coupled plasma-mass spectrometry (ICP-MS) and the profile of selenium species in the flour and bread were determined using high performance liquid chromatography (HPLC) ICP-MS. The selenium concentration of flour ranged from 30ng/g in white flour and 35ng/g in wholemeal flour from untreated plots up to >1800ng/g in white and >2200ng/g in wholemeal flour processed from grain treated with selenium (as selenate) at the highest application rate of 100g/ha. The relationship between the amount of selenium applied to the crop and the amount of selenium in flour and bread was approximately linear, indicating minimal loss of Se during grain processing and bread production. On average, application of selenium at 10g/ha increased total selenium in white and wholemeal bread by 155 and 185ng/g, respectively, equivalent to 6.4 and 7.1µg selenium per average slice of white and wholemeal bread, respectively. Selenomethionine accounted for 65-87% of total extractable selenium species in Se-enriched flour and bread; selenocysteine, Se-methylselenocysteine selenite and selenate were also detected. Controlled agronomic biofortification of wheat crops for flour and bread production could provide an appropriate strategy to increase the intake of bioavailable selenium.

Ultra-simple wearable local sweat volume monitoring patch based on swellable hydrogels.

Quantifiably monitoring sweat rate and volume is important to assess the stress level of individuals and/or prevent dehydration, but despite intense research, a convenient, continuous, and low-cost method to monitor sweat rate and total sweat volume loss remains an un-met need. We present here an ultra-simple wearable sensor capable of measuring sweat rate and volume accurately. The device continuously monitors sweat rate by wicking the produced sweat into hydrogels that measurably swell in their physical geometry. The device has been designed as a simple to fabricate, low-cost, disposable patch. This patch exhibits stable and predictable operation over the maximum variable chemistry expected for sweat (pH 4-9 and salinity 0-100 mM NaCl). Preliminary in vivo testing of the patch has been achieved during aerobic exercise, and the sweat rates measured via the patch accurately follow actual sweat rates.

Arsenic uptake and metabolism in plants.

Arsenic (As) is an element that is nonessential for and toxic to plants. Arsenic contamination in the environment occurs in many regions, and, depending on environmental factors, its accumulation in food crops may pose a health risk to humans.Recent progress in understanding the mechanisms of As uptake and metabolism in plants is reviewed here. Arsenate is taken up by phosphate transporters. A number of the aquaporin nodulin26-like intrinsic proteins (NIPs) are able to transport arsenite,the predominant form of As in reducing environments. In rice (Oryza sativa), arsenite uptake shares the highly efficient silicon (Si) pathway of entry to root cells and efflux towards the xylem. In root cells arsenate is rapidly reduced to arsenite, which is effluxed to the external medium, complexed by thiol peptides or translocated to shoots. One type of arsenate reductase has been identified, but its in planta functions remain to be investigated. Some fern species in the Pteridaceae family are able to hyperaccumulate As in above-ground tissues. Hyperaccumulation appears to involve enhanced arsenate uptake, decreased arsenite-thiol complexation and arsenite efflux to the external medium, greatly enhanced xylem translocation of arsenite, and vacuolar sequestration of arsenite in fronds. Current knowledge gaps and future research directions are also identified.

Arsenite efflux is not enhanced in the arsenate-tolerant phenotype of Holcus lanatus.

Arsenate tolerance in Holcus lanatus is achieved mainly through suppressed arsenate uptake. We recently showed that plant roots can rapidly efflux arsenite to the external medium. Here, we tested whether arsenite efflux is a component of the adaptive arsenate tolerance in H. lanatus. Tolerant and nontolerant phenotypes were exposed to different arsenate concentrations with or without phosphate for 24 h, and arsenic (As) speciation was determined in nutrient solutions, roots and xylem sap. At the same arsenate exposure concentration, the nontolerant phenotype took up more arsenate and effluxed more arsenite than the tolerant phenotype. However, arsenite efflux was proportional to arsenate uptake and was not enhanced in the tolerant phenotype. Within 2-24 h, most (80-100%) of the arsenate taken up was effluxed to the medium as arsenite. About 86-95% of the As in the roots and majority of the As in xylem sap (c. 66%) was present as arsenite, and there were no significant differences between phenotypes. Arsenite efflux is not adaptively enhanced in the tolerant phenotype H. lanatus, but it could be a basal tolerance mechanism to greatly decrease cellular As burden in both phenotypes. Tolerant and nontolerant phenotypes had a similar capacity to reduce arsenate in roots.

Inhibitory effects of c-erbB-2 antisense oligonucleotide transfection on uterine endometrial cancer Ishikawa cell lines.

BACKGROUND: C-erbB-2 is a chief proto-oncogene of endometrial cancer, which plays an important role in the biological behavior of endometrial cancer. Its overespression is an important factor of poor progrosis. The objective of this study was to investigate the treatment effects of transfecting c-erbB-2 antisense oligonucleotide (ASODN) on the uterine endometrial cancer Ishikawa cell line. MATERIALS AND METHODS: The c-erbB-2 expression on Ishikawa cell membranes was determined by immunohistochemistry and then the aim was to transfect ASODN into Ishikawa cells and assay the cellular growth inhibition by MTT, to observe the cellular ultrastructure changes under transmission electron microscope (TEM), and to assay the cellular apoptotic rate, c-erbB-2 mRNA and protein expression by flow cytometry, RT-PCR and Western blot, respectively. RESULTS: C-erbB-2 protein was positively expressed on Ishikawa cell membranes. MTT showed that when the concentration of transfecting ASODNs was 0.3 uM and 0.6 uM, cell growth inhibition rates were 55.43% and 76.12%, respectively. After transfecting 0.3 uM ASODN, the Ishikawa cell ultrastructure was obviously damaged, the cellular apoptotic rate was 72.21%, and the c-erbB-2 mRNA and protein expression were 45.71% and 34.52%, respectively, compared with those of the normal control cells. CONCLUSIONS: Transfecting c-erbB-2 ASODN can obviously suppress its mRNA and protein expression in Ishikawa cells, cause cellular apoptosis and inhibit cell growth. It may have an important role in the gene therapy of endometrial cancer.

Highly efficient xylem transport of arsenite in the arsenic hyperaccumulator Pteris vittata.

The hyperaccumulator Pteris vittata translocates arsenic (As) from roots to fronds efficiently, but the form of As translocated in xylem and the main location of arsenate reduction have not been resolved. Here, P. vittata was exposed to 5 microM arsenate or arsenite for 1-24 h, with or without 100 microM phosphate. Arsenic speciation was determined in xylem sap, roots, fronds and nutrient solutions by high-performance liquid chromatography (HPLC) linked to inductively coupled plasma mass spectrometry (ICP-MS). The xylem sap As concentration was 18-73 times that in the nutrient solution. In both arsenate- and arsenite-treated plants, arsenite was the predominant species in the xylem sap, accounting for 93-98% of the total As. A portion of arsenate taken up by roots (30-40% of root As) was reduced to arsenite rapidly. The majority (c. 80%) of As in fronds was arsenite. Phosphate inhibited arsenate uptake, but not As translocation. More As was translocated to fronds in the arsenite-treated than in the arsenate-treated plants. There was little arsenite efflux from roots to the external solution. Roots are the main location of arsenate reduction in P. vittata. Arsenite is highly mobile in xylem transport, possibly because of efficient xylem loading, little complexation with thiols in roots, and little efflux to the external medium.

Variation in root-to-shoot translocation of cadmium and zinc among different accessions of the hyperaccumulators Thlaspi caerulescens and Thlaspi praecox.

Efficient root-to-shoot translocation is a key trait of the zinc/cadmium hyperaccumulators Thlaspi caerulescens and Thlaspi praecox, but the extent of variation among different accessions and the underlying mechanisms remain unclear. Root-to-shoot translocation of Cd and Zn and apoplastic bypass flow were determined in 10 accessions of T. caerulescens and one of T. praecox, using radiolabels (109)Cd and (65)Zn. Two contrasting accessions (Pr and Ga) of T. caerulescens were further characterized for TcHMA4 expression and metal compartmentation in roots. Root-to-shoot translocation of (109)Cd and (65)Zn after 1 d exposure varied 4.4 to 5-fold among the 11 accessions, with a significant correlation between the two metals, but no significant correlation with uptake or the apoplastic bypass flow. The F(2) progeny from a cross between accessions from Prayon, Belgium (Pr) and Ganges, France (Ga) showed a continuous phenotype pattern and transgression. There was no significant difference in the TcHMA4 expression in roots between Pr and Ga. Compartmentation analysis showed a higher percentage of (109)Cd sequestered in the root vacuoles of Ga than Pr, the former being less efficient in translocation than the latter. Substantial natural variation exists in the root-to-shoot translocation of Cd and Zn, and root vacuolar sequestration may be an important factor related to this variation.

Estimates of ambient background concentrations of trace metals in soils for risk assessment.

Site-specific or soil type-specific ambient background concentrations (ABCs) of trace metals in soils are needed for risk assessment. We investigated three different methods for estimating ABCs in soils using a dataset of 5691 soil samples from England and Wales. The concentrations of Co, Cr and Ni were strongly associated with Al and Fe, and multiple regressions explained 62-85% of their variation, and Al and Fe can therefore be used to predict ABCs for these metals. Soil texture had a major influence on the concentrations of Cd, Co, Cr, Cu, Ni and Zn, and the medians were 3-5 fold higher in clayey than in sandy soils. This was used to predict texture-specific ABCs. Lead concentration was higher in acidic peaty soils than in other soils. A probability graph method was used to estimate ABC for Pb in a population of relatively uncontaminated soils. Potential applications of ABCs are discussed.

Role of salicylic acid in alleviating oxidative damage in rice roots (Oryza sativa) subjected to cadmium stress.

Time-dependent changes in enzymatic and non-enzymatic antioxidants, and lipid peroxidation were investigated in roots of rice (Oryza sativa) grown hydroponically with Cd, with or without pretreatment of salicylic acid (SA). Exposure to 50 microM Cd significantly decreased root growth, and activities of superoxide dismutase (SOD), catalase (CAT) and peroxidase (POD), but increased the concentrations of H(2)O(2), malondialdehyde (MDA), ascorbic acid (AsA), glutathione (GSH) and non-protein thiols (NPT). However, pretreatment with 10 microM SA enhanced the activities of antioxidant enzymes and the concentrations of non-enzymatic antioxidants, but lowered the concentrations of H(2)O(2) and MDA in the Cd-stressed rice compared with the Cd treatment alone. Pretreatment with SA alleviated the Cd-induced inhibition of root growth. The results showed that pretreatment with SA enhanced the antioxidant defense activities in Cd-stressed rice, thus alleviating Cd-induced oxidative damage and enhancing Cd tolerance. The possible mechanism of SA-induced H(2)O(2) signaling in mediating Cd tolerance was discussed.

Efficacy of c-erbB-2 antisense oligonucleotide transfection on uterine endometrial cancer HEC-1A cell lines.

OBJECTIVE: Antigene therapy targeting only one oncogene has made much progress although it still has some limitations. To explore the potential for antigene therapy in uterine endometrial cancer, we examined the in vitro inhibitory effects of liposmal anti-sense phosphorothioate oligonucleotides targeting c-erbB-2 in the human uterine endometrial cancer HEC-1A cell line. METHODS: 1) To detect c-erbB-2 protein expression on HEC-1A cell membranes by immunohisto- chemistry. 2) To assay cellular growth inhibition by MTT after transfecting 0.1-0.6 microM ASODN. 3) To observe cellular and ultra-structural changes under transmission electron microscope and to assay the cellular apoptotic rate by flow cytometry and c-erbB-2 mRNA, and protein expression by RT-PCR and Western blot after transfecting 0.3 microM ASODN. RESULTS: 1) c-erbB-2 protein expression was positive on HEC-1A cell membranes. 2) With the increase of the transfecting ASODN concentration from 0.1-0.6 microM, HEC-1A cellular growth inhibition was also enhanced. The results of MTT showed that when the transfecting concentration of ASODN was 0.3 microM, the HEC-1A cellular growth inhibition rate was 50% while when the transfecting concentration of ASODN was 0.6 microM, the HEC-1A cell growth inhibition rate was 75%. 3) When the concentration of transfecting ASODNs was 0.3 microM, there were obvious vacuolar degenerations in the plasma of HEC-1A cells, disappearance of organelle and nuclear structure and obvious shrinkage of nuclei under transmission electron microscope. The cellular apoptotic rate was 62.80%, while c-erbB-2 mRNA and protein expression were 47.18% and 33.60%, respectively, compared with those of the normal control cells. CONCLUSION: Transfecting c-erbB-2 ASODNs can obviously suppress the mRNA and protein expression in HEC-1A cells, cause cellular apoptosis and inhibit cell growth. It may be a more useful gene therapy for endometrial cancer.

Field evaluation of in situ remediation of a heavy metal contaminated soil using lime and red-mud.

We evaluated the effectiveness of lime and red mud (by-product of aluminium manufacturing) to reduce metal availability to Festuca rubra and to allow re-vegetation on a highly contaminated brown-field site. Application of both lime and red mud (at 3 or 5%) increased soil pH and decreased metal availability. Festuca rubra failed to establish in the control plots, but grew to a near complete vegetative cover on the amended plots. The most effective treatment in decreasing grass metal concentrations in the first year was 5% red mud, but by year two all amendments were equally effective. In an additional pot experiment, P application in combination with red mud or lime decreased the Pb concentration, but not total uptake of Pb in Festuca rubra compared to red mud alone. The results show that both red mud and lime can be used to remediate a heavily contaminated acid soil to allow re-vegetation.

Field evaluation of Cd and Zn phytoextraction potential by the hyperaccumulators Thlaspi caerulescens and Arabidopsis halleri.

Field trials were undertaken to investigate the effect of the application of metal mobilizing agents, different sowing strategies and length of growing season on the extraction of Cd and Zn from soils by Thlaspi caerulescens and Arabidopsis halleri. None of the mobilizing agents used enhanced metal accumulation by T. caerulescens. Between 1998 and 2000, on average across plots where Cd or Zn exceeded allowable limits, T. caerulescens removed 1.3 and 0.3% of the total soil Cd and Zn. In one season when T. caerulescens was grown for 14 months, 21.7 and 4.4% of the total soil Cd and Zn was removed. This was larger than values found when T. caerulescens was grown for 4 months. A. halleri accumulated similar concentrations of Zn, but lower Cd concentrations than T. caerulescens. The results indicate that metal phytoextraction using T. caerulescens can be used to clean up soils moderately contaminated by Cd.

Maternal zinc deficiency impairs brain nestin expression in prenatal and postnatal mice.

Effects of maternal dietary zinc deficiency on prenatal and postnatal brain development were investigated in ICR strain mice. From d 1 of pregnancy (E0) until postnatal d 20 (P20), maternal mice were fed experimental diets that contained 1 mg Zn/kg/day (severe zinc deficient, SZD), 5 mg Zn/kg/day (marginal zinc deficient, MZD), 30 mg Zn/kg/day (zinc adequately supplied, ZA) or 100 mg Zn/kg/day (zinc supplemented, ZS and pair-fed, PF). Brains of offspring from these dietary groups were examined at various developmental stages for expression of nestin, an intermediate filament protein found in neural stem cells and young neurons. Immunocytochemistry showed nestin expression in neural tube 10.5 d post citrus (dpc) as well as in the cerebral cortex and neural tube from 10.5 dpc to postnatal d 10 (P10). Nestin immunoreactivities in both brain and neural tube of those zinc-supplemented control groups (ZA, ZS, PF) were stronger than those in zinc-deficient groups (SZD and MZD). Western blot analysis confirmed that nestin levels in pooled brain extracts from each of the zinc-supplemented groups (ZA, ZS, PF) were much higher than those from the zinc-deficient groups (SZD and MZD) from 10.5 dpc to P10. Immunostaining and Western blots showed no detectable nestin in any of the experimental and control group brains after P20. These observations of an association between maternal zinc deficiency and decreased nestin protein levels in brains of offspring suggest that zinc deficiency suppresses development of neural stem cells, an effect which may lead to neuroanatomical and behavioral abnormalities in adults.

Root exudates of the hyperaccumulator Thlaspi caerulescens do not enhance metal mobilization.

• To examine whether root exudates of the Zn/Cd hyperaccumulator Thlaspi caerulescens play a role in metal hyperaccumulation, we compared the metal mobilization capacity of root exudates collected from two ecotypes of T. caerulescens, and from the nonaccumulators wheat (Triticum aestivum) and canola (Brassica napus). • Plants were grown hydroponically and three treatments (control, -Fe and -Zn) were later imposed for 2 wk before collection of root exudates. • On a basis of root d. wt, the total soluble organic C in the root exudates of T. caerulescens was similar to that of wheat, and significantly higher than that of canola. In all treatment, the root exudates of T. caerulescens and canola mobilized little Cu and Zn from Cu- or Zn-loaded resins, and little Zn, Cd, Cu or Fe from a contaminated calcareous soil. By contrast, the root exudates of wheat generally mobilized more metals from both resin and soil. In particular, the -Fe treatment, and to a lesser extent the -Zn treatment, elicited large increases in the metal mobilization capacity of the root exudates from wheat. • We conclude that root exudates from T. caerulescens do not significantly enhance mobilization of Zn and Cd, and therefore are not involved in Zn and Cd hyperaccumulation.

Physiological evidence for a high-affinity cadmium transporter highly expressed in a Thlaspi caerulescens ecotype.

• Uptake kinetics and translocation characteristics of cadmium and zinc are presented for two contrasting ecotypes of the Cd/Zn hyperaccumulator Thlaspi caerulescens, Ganges (southern France) and Prayon (Belgium). • Experiments using radioactive isotopes were designed to investigate the physiology of Cd and Zn uptake, and a pressure-chamber system was employed to collect xylem sap. • In contrast to similar Zn uptake and translocation, measurements of concentration-dependent influx of Cd revealed marked differences between ecotypes. Ganges alone showed a clear saturable component in the low Cd concentration range; maximum influx Vmax for Cd was fivefold higher in Ganges; and there was a fivefold difference in the Cd concentration in xylem sap. Addition of Zn to the uptake solution at equimolar concentration to Cd did not decrease Cd uptake by Ganges, but caused a 35% decrease in Prayon. • There is strong physiological evidence for a high-affinity, highly expressed Cd transporter in the root cell plasma membranes of the Ganges ecotype of T. caerulescens. This raises evolutionary questions about specific transporters for non-essential metals. The results also show the considerable scope for selecting hyperaccumulator ecotypes to achieve higher phytoextraction efficiencies.

Co-segregation analysis of cadmium and zinc accumulation in Thlaspi caerulescens interecotypic crosses.

• Cadmium (Cd) hyperaccumulation in Thlaspi caerulescens varies among ecotypes. Here we investigated segregation of Cd and zinc (Zn) accumulation in F2 crosses between high (Ganges) and low (Prayon) Cd-accumulating ecotypes. • Accumulation was measured in plants grown in compost treated with 5 and 100 mg kg-1 Cd and Zn, respectively, and in hydroponics with 50 m Zn and 10 or 50 m Cd. Another hydroponic experiment examined the relationship between Cd tolerance and accumulation. • Parental phenotype distributions for shoot metal concentrations were distinct for Cd, but not consistent for Zn. Shoot Cd and Zn in F2 s varied continuously, with significant transgression for Zn in all treatments. Shoot Cd correlated strongly with shoot manganese (Mn), and to a lesser degree with shoot Zn. Shoot Cd concentrations in the Cd nontolerant F2 s were lower than, or similar to, those in the Cd-tolerant F2 s. • We conclude that Cd and Zn accumulation is governed by multiple genes, and that Cd tolerance and accumulation are independent traits in T. caerulescens. Two uptake systems with distinctive affinities for Cd, Zn and Mn are proposed.

The role of phytochelatins in arsenic tolerance in the hyperaccumulator Pteris vittata.

• Pteris vittata was the first identified arsenic (As) hyperaccumulator. Here we investigated whether phytochelatins (PCs) are involved in the hypertolerance of arsenic by P. vittata. • P. vittata was exposed to 0-500 µm arsenate for 5 d, or to 50 µm arsenate for 0-7 d. In addition, l-buthionine-sulphoximine (BSO), an inhibitor of γ-glutamylcysteine synthetase, was used in combination with different arsenate exposures. The relationships between As accumulation and the concentrations of PCs and glutathione (GSH) were examined. • PC synthesis was induced upon exposure to arsenate in P. vittata, with only PC2 detected in the plant. The As concentration correlated significantly with PC2 concentration in both roots and shoots, but not with GSH. The molar ratio of PC-SH to As was c. 0.09 and 0.03 for shoots and roots, respectively, suggesting that only a small proportion (1-3%) of the As in P. vittata can be complexed with PCs. In the presence of arsenate, addition of BSO decreased PC2 concentrations in roots and shoots by 89-96% and 30-33%, respectively. BSO alone was found to inhibit root growth of P. vittata markedly. • The results suggest that PCs play a limited role in the hypertolerance of As in P. vittata.

Arsenic hyperaccumulation by Pteris vittata from arsenic contaminated soils and the effect of liming and phosphate fertilisation.

Pot experiments were carried out to investigate the potential of phytoremediation with the arsenic hyperaccumulator Pteris vittata in a range of soils contaminated with As and other heavy metals, and the influence of phosphate and lime additions on As hyperaccumulation by P. vittata. The fern was grown in 5 soils collected from Cornwall (England) containing 67-4550 mg As kg(-1) and different levels of metals. All soils showed a similar distribution pattern of As in different fractions in a sequential extraction, with more than 60% of the total As being associated with the fraction thought to represent amorphous and poorly-crystalline hydrous oxides of Fe and Al. The concentration of As in the fronds ranged from 84 to 3600 mg kg(-1), with 0.9-3.1% of the total soil As being taken up by P. vittata. In one soil which contained 5500 mg Cu kg(-1) and 1242 mg Zn kg(-1), P. vittata suffered from phytotoxicity and accumulated little As (0.002% of total). In a separate experiment, neither phosphate addition (50mg P kg(-1) soil) nor liming (4.6 g CaCO3 kg(-1) soil) was found to affect the As concentration in the fronds of P. vittata, even though phosphate addition increased the As concentration in the soil pore water. Between 4 and 7% of the total soil As was taken up by P. vittata in 4 cuttings in this experiment. The results indicate that P. vittata can hyperaccumulate As from naturally contaminated soils, but may be suitable for phytoremediation only in the moderately contaminated soils.