Presence Of Chlorate Research Articles

Magnetite Survivability and Non‐Stoichiometric Magnetite Formation in Presence of Oxyhalogen Brines on Mars

AbstractThe mixed Fe(II)/Fe(III) mineral magnetite [Fe3O4] of various stoichiometric and non‐stoichiometric compositions have been reported in Martian soils and rocks by several rover missions. Magnetite is an important paleomagnetic indicator mineral and can serve as a ‘biogeobattery’ as a consequence of its magnetic properties and the mixed valence state of iron in its structure. Here, we assess the extent of oxidative weathering of magnetite in presence of chlorate and bromate containing solutions that are likely important oxidants on Mars. Oxyhalogen species, chlorate and bromate, produced non‐stoichiometric magnetite [Fe(II)/Fe(III) < 0.5] in Mars‐relevant, near‐neutral pH fluids; no other ferric minerals were produced. The same results were observed in highly acidic fluids with or without oxyhalogens. Owing to its resistance to extensive oxidation, magnetite can serve as an important archive of geochemical, paleomagnetic, and astrobiological information in samples that will be returned by the Mars Sample Return mission.

The combined leaching of copper, gold and uranium in chloride solutions. I. Chalcopyrite

In a study (Part II) aimed at the simultaneous heap leaching of copper (predominantly chalcopyrite), gold and uranium from an ore, it was found that this could be achieved using chlorate as the oxidant in chloride solutions. As a result, a more detailed study has been made using electrochemical and batch leach tests on pure chalcopyrite electrodes under typical heap leach conditions.The use of chlorate at moderately low concentrations has shown that enhanced rates of dissolution of chalcopyrite can be maintained over periods up to 4 days at ambient temperatures in acidic chloride solutions. The rate of dissolution is enhanced at higher acid concentrations. The rate in the presence of chlorate does not appear to depend on the iron(III) (and presumably the copper(II)) concentration.The observed rates are significantly greater than those predicted for oxidative dissolution from the electrochemistry and the mixed potential model. An alternative non-oxidative mechanism has been revisited to account for this difference.A preliminary measurement has been made of the kinetics of the oxidation of hydrogen sufide and iron(III) by low concentrations of chlorine produced by reaction of chlorate with chloride ions. These reactions are rapid, and theory shows that they would support the proposed non-oxidative mechanism.

Presence of Chlorate and Perchlorate Residues in Raw Bovine Milk from Italian Farms.

Chlorates and perchlorates are endocrine disruptors and emerging environmental contaminants found in various types of foods, including milk and dairy products. The presence of chlorate has been associated with the use of chlorine-based sanitizers to disinfect equipment and water used in food processing. Perchlorate, on the other hand, occurs naturally in the environment but is also released from anthropogenic sources. To protect consumers, the EU set an MRL for chlorate in milk but not for perchlorate. Considering that data on chlorates and perchlorates in this field are limited, the objective of this study was to assess the presence of these two anions in 148 samples of raw bovine milk collected from different farms of Lombardy and grouped in three different geographical zones. Chlorate was detected in 73% of the samples analyzed, at concentrations ranging from <LOQ to 18.70 μg kg−1 with an average value of 7.10 ± 5.88 μg kg−1 below the MRL; perchlorate with a frequency of 99%, in the range from <LOQ to 6.95 μg kg−1 and an average value of 4.06 ± 1.58 μg kg−1. No significant differences were detected among the three geographical zones. An evaluation of the estimated daily intake of perchlorate through milk confirmed the absence of risk for Italian consumers.

The effect of impurities on the stability of low concentrated eco-friendly solutions of NaOCl

The synthesis of hypochlorous acid from low concentrated chloride-containing electrolytes has been studied on various oxide materials at the anode current density of 50 mA cm–2. Boron doped diamond, platinized titanium, metallic titanium doped with platinum and palladium and materials based on lead (IV) oxide modified with fluorine and surfactants turned out to be promising for the synthesis of hypochlorous acid by electrolysis. Whereas, given the stability of oxidant synthesis during cumulative electrolysis, titanium modified with platinum and palladium as well as pre-treated lead (IV) oxide containing surfactants (sodium laureth sulfate) was the best. One should additionally take into account the possibility of combined use of electrocatalysts for the synthesis of strong oxidants in the reverse current mode in flow systems, when the implementation of the gas cathode leads to the formation of hydrogen peroxide and hypochlorous acid is formed at the anode. In fact, only a metal electrocatalyst, such as titanium modified with platinum and palladium, can be a suitable material. The kinetics of hypochlorite conversion is primarily determined by the pH value of freshly prepared solutions, temperature and storage conditions. The presence of different organic and inorganic micro-impurities in the solution also affects the kinetics of the hypochlorite salt decomposition. The following micro-impurities show the most negative impact on the stability of sodium hypochlorite solutions: Co(II), Cu(II), Mg(II), Al(III), and K3[Fe(CN)6]; Ni(ІІ), Fe(III), and K4[Fe(CN)6] influence the stability to a lesser extent. The effect of chlorate on the inhibition of sodium hypochlorite activity as a disinfectant has been investigated. The presence of chlorate in the disinfectant solution involved results in the absence of bactericidal activity against S. aureus and P. aeuruginosa. The growth of pseudomonas colonies becomes more abundant with increasing chlorate content in the disinfectant.

Use of Chlorine Dioxide to Treat Recirculated Process Water in a Commercial Tomato Packinghouse: Microbiological and Chemical Risks

Antimicrobial treatment of fresh produce wash water can enable water reuse by avoiding microbial cross-contamination. In this study, the efficacy of chlorine dioxide (ClO2; 2-3 mg/L) to maintain the microbiological quality of process wash water in a tomato packinghouse was assessed. Different parameters were measured, including the physicochemical characteristics of the wash water (pH, oxidation-reduction potential (ORP), chemical oxygen demand (COD), absorbance at 254 nm (UVA254), temperature, electrical conductivity (EC)), the levels of different microorganisms present in water and in the product (aerobic mesophilic bacteria (AMB), total coliforms, yeasts and molds, E. coli), and the presence of chlorate as disinfection by-product. The treatment with ClO2 had a significant effect on the microbial populations present in the recirculated wash water and the tomatoes compared with the use of untreated recirculated water. The microbial load in tomatoes washed with tap water, and ClO2-treated recirculated water was similar. The transfer of chlorate from wash water to the fruits was very low under the conditions tested. The results obtained indicate that ClO2 could be a suitable option for the reuse of wash water in commercial packinghouses, as it reduces the microbial populations in wash water while not leading to the presence of disinfection by-products, such as chlorate, in the final product. This study shows that the monitorization and control of the microbiological quality of process wash water should be managed together with good practices able to guarantee hygienic conditions of the equipment by implementing efficient cleaning and disinfection systems.

Pingyangmycin inhibits glycosaminoglycan sulphation in both cancer cells and tumour tissues.

Pingyangmycin is a clinically used anticancer drug and induces lung fibrosis in certain cancer patients. We previously reported that the negatively charged cell surface glycosaminoglycans are involved in the cellular uptake of the positively charged pingyangmycin. However, it is unknown if pingyangmycin affects glycosaminoglycan structures. Seven cell lines and a Lewis lung carcinoma‐injected C57BL/6 mouse model were used to understand the cytotoxicity of pingyangmycin and its effect on glycosaminoglycan biosynthesis. Stable isotope labelling coupled with LC/MS method was used to quantify glycosaminoglycan disaccharide compositions from pingyangmycin‐treated and untreated cell and tumour samples. Pingyangmycin reduced both chondroitin sulphate and heparan sulphate sulphation in cancer cells and in tumours. The effect was persistent at different pingyangmycin concentrations and at different exposure times. Moreover, the cytotoxicity of pingyangmycin was decreased in the presence of soluble glycosaminoglycans, in the glycosaminoglycan‐deficient cell line CHO745, and in the presence of chlorate. A flow cytometry‐based cell surface FGF/FGFR/glycosaminoglycan binding assay also showed that pingyangmycin changed cell surface glycosaminoglycan structures. Changes in the structures of glycosaminoglycans may be related to fibrosis induced by pingyangmycin in certain cancer patients.

Chlorination management in commercial fresh produce processing lines

Despite all the information available and the fact that the fresh produce industry has been active for more than 30 years, chlorination management of process wash water (PWW) still needs to be further optimized. It is necessary to adjust the chlorination management to the demanding goals of avoiding microbial cross-contamination and the presence of disinfection by-products (DBPs). In the present study, two commercial processing plants were examined, and the impact of chlorination management was studied by comparing two chlorine sources (chlorine gas and liquid chlorine) under manual and automatic control procedures. The effect of the reduction of water replenishment rates, product type and cut size, as well as product rinse, were also evaluated. Results showed that there was no presence of chlorate in PWW (<0.001 mg/L) and in the product (<0.001 mg/kg) when chlorine gas alone was used, while chlorate accumulation occurred in water (up to 16 mg/L) and product (>2 mg/kg) when liquid chlorine was combined to cope with the chlorine demand. Chlorination management using the automatic control system led to better free chlorine and pH regulation. pH levels using the automatic control were in the range 5.5–6.5, while pH was in the range 6.5–8.5 when using manual control systems. Fluctuations in the physicochemical and microbiological characteristics of PWW were linked to changes in product type and cut size. Chemical oxygen demand (COD) of PWW was twice as high when shredded lettuce was washed (1000–1800 mg/L) compared with chopped lettuce (500–900 mg/L). The microbial load in PWW was higher when washing baby leaves (≈4.0 log cfu/100 mL) compared with cut lettuce (≈2.5 log cfu/100 mL), and higher when washing shredded lettuce compared with chopped lettuce. Product type and cut size significantly affected chlorate residues removal by produce rinse. Tap water rinsing led to significant reductions (p < 0.05) in chlorate concentration in the case of chopped lettuce, but not in the case of shredded lettuce and baby leaves. This study highlights the importance of adequate chlorination management for chlorate residue mitigation, including the selection of chlorine source, control system, and proper water rinse. The concept that ‘one size does not fit all’ should be present when establishing the operational procedures for different commodities and product formats.

Chlorate and Other Oxychlorine Contaminants Within the Dairy Supply Chain

The presence of chlorate in milk and dairy products can arise from the use of chlorinated water and chlorinated detergents for cleaning and sanitation of process equipment at both farm and food processor level. Chlorate and other oxychlorine species have been associated with inhibition of iodine uptake in humans and the formation of methemoglobin, with infants and young children being a high-risk demographic. This comprehensive review of chlorate and chlorine derivatives in dairy, highlights areas of concern relative to the origin and/or introduction of chlorate within the dairy supply chain. This review also discusses the associated health concerns, regulations, and chemical behavior of chlorate and chlorine-derived by-products, and provides a summary of mechanisms for their detection and removal.

Chloroxyanion Residue on Seeds and Sprouts after Chlorine Dioxide Sanitation of Alfalfa Seed.

The effects of a 6-h chlorine dioxide sanitation of alfalfa seed (0, 50, 100, and 200 mg/kg seed) on total coliform bacteria, seed germination, and the presence of chlorate and perchlorate residues in seed rinse, seed soak, and alfalfa sprouts was determined. Chlorate residues in 20,000 mg/L calcium hypochlorite, commonly used to disinfect seed, were quantified. Chlorine dioxide treatment reduced (P < 0.05) total coliforms on seeds with no effect (P > 0.05) on germination. Dose-dependent sodium chlorate residues were present in seed rinse (4.1 to 31.2 μg/g seed) and soak (0.7 to 8.3 μg/g seed) waters, whereas chlorate residues were absent (LOQ 5 ng/g) in sprouts, except for 2 of 5 replicates from the high chlorine dioxide treatment. Copious chlorate residues were present (168 to 1260 mg/L) in freshly prepared 20,000 mg/L calcium hypochlorite solution, and storage at room temperature increased chlorate residues significantly (P < 0.01).

Electrochemical detection of chlorate on a novel nano-Au/TiO2NT electrode

The present work describes the synthesis, characterization and application of Au nanoparticles modified titanium nanotube electrode (Nano-Au/TiO2NT) as a novel and sensitive electrode material for electrochemical sensing of chlorate. For this purpose, highly ordered TiO2 nanotube (TiO2NT) electrode was synthesized by anodization of metallic titanium foil in ethylene glycol-water solution. Nano-Au/TiO2NT was obtained by drop casting a solution of homogeneous and fine structures of gold nanoparticles, which were prepared from HAuCl4 using a new simple photochemical process. Structural and elemental analysis characteristics of the resulting Nano-Au/TiO2NT electrode were investigated by scanning electron microscopy and X-ray diffraction analysis. The electrocchemical activity of resulted Nano-Au/TiO2NT electrode towards chlorate reduction in acidic solution was confirmed by cyclic voltammetry and chronoamperometry methods An enhancement of amperometric current in the presence of chlorate was afforded to chlorate detection with a low detection limit of 12μM and linear range of 50μM to 4.8mM.

Chlorates(VII) removal on Dowex™PSR-2 resin

&lt;p&gt;Lately there has been observed the increased presence of chlorates(VII) in the natural environment which can affect human health negatively. Therefore the removal of chlorate(VII) ions using the gel type resin functionalized with the tri-n-butyl ammonium (Dowex&lt;sup&gt;™&lt;/sup&gt;PSR-2) from waters was studied. The main aim was to evaluate the effects of experimental conditions including contact time, initial solution concentration, pH and temperature on chlorate(VII) ions removal as well as the anion exchanger properties on chlorate(VII) ions sorption. It was found that only the pseudo second order model described the experimental data well and the intraparticle diffusion was not the rate-limiting step. According to the Freundlich model, the q&lt;sub&gt;e&lt;/sub&gt; value was to be 69.26 mg/g at optimum conditions (pH 7.0 at 25 &lt;sup&gt;o&lt;/sup&gt;C).&lt;strong&gt;&lt;/strong&gt;&lt;/p&gt;

Characterisation of chlorate reduction in the haloarchaeon Haloferax mediterranei

BackgroundHaloferax mediterranei is a denitrifying haloarchaeon using nitrate as a respiratory electron acceptor under anaerobic conditions in a reaction catalysed by pNarGH. Other ions such as bromate, perchlorate and chlorate can also be reduced. MethodsHfx. mediterranei cells were grown anaerobically with nitrate as electron acceptor and chlorate reductase activity measured in whole cells and purified nitrate reductase. ResultsNo genes encoding (per)chlorate reductases have been detected either in the Hfx. mediterranei genome or in other haloarchaea. However, a gene encoding a chlorite dismutase that is predicted to be exported across the cytoplasmic membrane has been identified in Hfx. mediterranei genome. Cells did not grow anaerobically in presence of chlorate as the unique electron acceptor. However, cells anaerobically grown with nitrate and then transferred to chlorate-containing growth medium can grow a few generations. Chlorate reduction by the whole cells, as well as by pure pNarGH, has been characterised. No clear chlorite dismutase activity could be detected. ConclusionsHfx. mediterranei pNarGH has its active site on the outer-face of the cytoplasmic membrane and reacts with chlorate and perchlorate. Biochemical characterisation of this enzymatic activity suggests that Hfx. mediterranei or its pure pNarGH could be of great interest for waste water treatments or to better understand biological chlorate reduction in early Earth or Martian environments. General significanceSome archaea species reduce (per)chlorate. However, results here presented as well as those recently reported by Liebensteiner and co-workers [1] suggest that complete perchlorate reduction in archaea follows different rules in terms of biological reactions.

Assessment of residual active chlorine in sodium hypochlorite solutions after dissolution of porcine incisor pulpal tissue

In previous studies, surfactant-containing Hypochlor brands of sodium hypochlorite showed better tissue solubilizing abilities than Milton; differences not explained by original active chlorine content or presence of surfactant. It was postulated that exhaustion of active chlorine content could explain differences. This study aimed to assess whether Milton's poorer performance was due to exhaustion of active chlorine. Parallel experiments assessed the influence of titration methods, and the presence of chlorates, on active chlorine measurements. Time required to dissolve one or groups of 10 samples of porcine incisor pulp samples in Milton was determined. Residual active chlorine was assessed by thermometric titration. Iodometric and thermometric titration was carried out on samples of Milton. Chlorate content was also measured. Dissolution of single and 10 pulp samples caused a mean loss of 1% and 3% respectively of active chlorine, not being proportional to tissue dissolved. Thermometric ammonium ion titration resulted in 10% lower values than iodometric titration. Chlorate accounted for much of this difference. Depletion of active chlorine is not the reason for differences in tissue dissolving capabilities of Milton. Thermometric ammonium ion titration gives more accurate measurement of active chlorine content than iodometric titration.

Syndecan 4 interacts genetically with Vangl2 to regulate neural tube closure and planar cell polarity

Syndecan 4 (Sdc4) is a cell-surface heparan sulfate proteoglycan (HSPG) that regulates gastrulation, neural tube closure and directed neural crest migration in Xenopus development. To determine whether Sdc4 participates in Wnt/PCP signaling during mouse development, we evaluated a possible interaction between a null mutation of Sdc4 and the loop-tail allele of Vangl2. Sdc4 is expressed in multiple tissues, but particularly in the non-neural ectoderm, hindgut and otic vesicles. Sdc4;Vangl2Lp compound mutant mice have defective spinal neural tube closure, disrupted orientation of the stereocilia bundles in the cochlea and delayed wound healing, demonstrating a strong genetic interaction. In Xenopus, co-injection of suboptimal amounts of Sdc4 and Vangl2 morpholinos resulted in a significantly greater proportion of embryos with defective neural tube closure than each individual morpholino alone. To probe the mechanism of this interaction, we overexpressed or knocked down Vangl2 function in HEK293 cells. The Sdc4 and Vangl2 proteins colocalize, and Vangl2, particularly the Vangl2Lp mutant form, diminishes Sdc4 protein levels. Conversely, Vangl2 knockdown enhances Sdc4 protein levels. Overall HSPG steady-state levels were regulated by Vangl2, suggesting a molecular mechanism for the genetic interaction in which Vangl2Lp/+ enhances the Sdc4-null phenotype. This could be mediated via heparan sulfate residues, as Vangl2Lp/+ embryos fail to initiate neural tube closure and develop craniorachischisis (usually seen only in Vangl2Lp/Lp) when cultured in the presence of chlorate, a sulfation inhibitor. These results demonstrate that Sdc4 can participate in the Wnt/PCP pathway, unveiling its importance during neural tube closure in mammalian embryos.

Syndecan 4 interacts genetically with Vangl2 to regulate neural tube closure and planar cell polarity

Syndecan 4 (Sdc4) is a cell-surface heparan sulfate proteoglycan (HSPG) that regulates gastrulation, neural tube closure and directed neural crest migration in Xenopus development. To determine whether Sdc4 participates in Wnt/PCP signaling during mouse development, we evaluated a possible interaction between a null mutation of Sdc4 and the loop-tail allele of Vangl2. Sdc4 is expressed in multiple tissues, but particularly in the non-neural ectoderm, hindgut and otic vesicles. Sdc4;Vangl2Lp compound mutant mice have defective spinal neural tube closure, disrupted orientation of the stereocilia bundles in the cochlea and delayed wound healing, demonstrating a strong genetic interaction. In Xenopus, co-injection of suboptimal amounts of Sdc4 and Vangl2 morpholinos resulted in a significantly greater proportion of embryos with defective neural tube closure than each individual morpholino alone. To probe the mechanism of this interaction, we overexpressed or knocked down Vangl2 function in HEK293 cells. The Sdc4 and Vangl2 proteins colocalize, and Vangl2, particularly the Vangl2Lp mutant form, diminishes Sdc4 protein levels. Conversely, Vangl2 knockdown enhances Sdc4 protein levels. Overall HSPG steady-state levels were regulated by Vangl2, suggesting a molecular mechanism for the genetic interaction in which Vangl2Lp/+ enhances the Sdc4-null phenotype. This could be mediated via heparan sulfate residues, as Vangl2Lp/+ embryos fail to initiate neural tube closure and develop craniorachischisis (usually seen only in Vangl2Lp/Lp) when cultured in the presence of chlorate, a sulfation inhibitor. These results demonstrate that Sdc4 can participate in the Wnt/PCP pathway, unveiling its importance during neural tube closure in mammalian embryos.

Organization of the neuroepithelial actin cytoskeleton is regulated by heparan sulfation during neurulation

Heparan sulfate and cytoskeletal actin microfilaments have both been shown to be important regulators of neural tube closure during embryonic development. To determine the functional relationship of these two molecules in formation of the spinal neural tube, we cultured ARC mouse embryos at embryonic day E8.5 in the presence of chlorate, a competitive inhibitor of glycosaminoglycan sulfation, and examined the effects on organization of actin microfilaments in the neuroepithelium. Compared against embryos cultured under control conditions, chlorate-treated embryos had shortened posterior neuropore, a loss of median hinge point formation and increased bending at the paired dorsolateral hinge points. Furthermore, apical organization of actin microfilaments in the neuroepithelial cells was absent, and this was associated with convex bending of the neuroepithelium. The results suggest that heparan sulfate is an important determinant of cytoskeletal actin organization during spinal neurulation, and that its biological action is dependent on sulfation of the heparan molecule.

Expression of Chlorite Dismutase and Chlorate Reductase in the Presence of Oxygen and/or Chlorate as the Terminal Electron Acceptor in Ideonella dechloratans

The ability of microorganisms to perform dissimilatory (per)chlorate reduction is, for most species, known to be oxygen sensitive. Consequently, bioremediation processes for the removal of oxochlorates will be disturbed if oxygen is present. We measured the expression of chlorite dismutase and chlorate reductase in the presence of different terminal electron acceptors in the chlorate reducer Ideonella dechloratans. Enzyme activity assays and mRNA analyses by real-time quantitative reverse transcription (qRT)-PCR were performed on cell extracts from cells grown aerobically with and without chlorate and on cells grown anaerobically in the presence of chlorate. Our results showed that both chlorite dismutase and chlorate reductase are expressed during aerobic growth. However, transfer to anaerobic conditions with chlorate resulted in significantly enhanced enzyme activities and mRNA levels for both enzymes. Absence of oxygen was necessary for the induction to occur, since chlorate addition under aerobic conditions produced neither increased enzyme activities nor higher relative levels of mRNA. For chlorite dismutase, the observed increase in activity was on the same order of magnitude as the increase in the relative mRNA level, indicating gene regulation at the transcriptional level. However, chlorate reductase showed about 200 times higher enzyme activity in anaerobically induced cells, whereas the increase in mRNA was only about 10-fold, suggesting additional mechanisms influence the enzyme activity.

Chlorate-induced Inhibition of Nitrate Uptake Mediated by Enterobacter amnigenus GG0461

Enterobacter amnigenus GG0461, isolated and identified from greenhouse soils, has a high activity of nitrate uptake in the Pseudomonas agar factor medium. Although nitrate is not essential for the growth of this microorganism, it increases the growth rate. To characterize the microbial nitrate uptake, we measured the effect of chlorate on the uptake, since chlorate is an inhibitor of plant nitrate uptake. In the absence of nitrate, the growth of E. amnigenus was inhibited by chlorate at concentrations higher than 1 mM. In the presence of 50 mM nitrate, nitrate uptake was completely inhibited by 30 mM of chlorate, and growth was suppressed by chlorate at concentrations above 10 mM. In the presence of chlorate, the growth and nitrate uptake gradually improved when nitrate concentration increased. To overcome the inhibitory effect of chlorate, the nitrate concentration was required to be 2.5 times higher than that of chlorate, suggesting that there exists competition between chlorate and nitrate for the binding site of the nitrate transporter. Chlorate-induced inhibitions of bacterial nitrate uptake and growth seemed to have different mechanisms: a competitive inhibition in the former case and the formation of chlorite, a toxic reduced metabolite of chlorate, in the latter case.

Involvement of Phytosulfokine in the Attenuation of Stress Response during the Transdifferentiation of Zinnia Mesophyll Cells into Tracheary Elements

Phytosulfokine (PSK) is a sulfated peptide hormone required for the proliferation and differentiation of plant cells. Here, we characterize the physiological roles of PSK in transdifferentiation of isolated mesophyll cells of zinnia (Zinnia elegans 'Canary Bird') into tracheary elements (TEs). Transcripts for a zinnia PSK precursor gene, ZePSK1, show two peaks of expression during TE differentiation; the first accumulation is transiently induced in response to wounding at 24 h of culture, and the second accumulation is induced in the final stage of TE differentiation and is dependent on endogenous brassinosteroids. Chlorate, a potent inhibitor of peptide sulfation, is successfully applied as an inhibitor of PSK action. Chlorate significantly suppresses TE differentiation. The chlorate-induced suppression of TE differentiation is overcome by exogenously applied PSK. In the presence of chlorate, expression of stress-related genes for proteinase inhibitors and a pathogenesis-related protein is enhanced and changed from a transient to a continuous pattern. On the contrary, administration of PSK significantly reduces the accumulation of transcripts for the stress-related genes. Even in the absence of auxin and cytokinin, addition of PSK suppresses stress-related gene expression. Microarray analysis reveals 66 genes down-regulated and 42 genes up-regulated in the presence of PSK. The large majority of down-regulated genes show significant similarity to various families of stress-related proteins, including chitinases, phenylpropanoid biosynthesis enzymes, 1-aminocyclopropane-1-carboxylic acid synthase, and receptor-like protein kinases. These results suggest the involvement of PSK in the attenuation of stress response and healing of wound-activated cells during the early stage of TE differentiation.

Disinfection By-Products in Drinking Water: A Comparison Between Chlorine and Chlorine Dioxide

ISEE-314 Objective: To evaluate Disinfection By Products (DBPs) and relative amounts in drinking water following chlorine and/or chlorine dioxide treatments in comparison. Material and Methods: In July 2005 to February 2006 12 waterworks (managed by “Agenzia d'Ambito per i Servizi Pubblici di Modena”-ATO) in Northern Italy were sampled twice, in summer and winter. In each sampling session 4 samples were collected: just before and immediately after the treatment, at the tap close to the disinfection plant and far from the plant. Main DBPs (trihalomethanes, chlorite, chlorate, bromate, and haloacetic acids) were investigated by headspace gas chromatography and ionic chromatography/mass spectrometry techniques. Results: Nine water networks were supplied by ground water and 3 by mixed spring and surface water: chlorine was used for disinfection in 4 water systems and chlorine dioxide in 8. Bromate and haloacetic acids were never evidenced, whereas trihalomethanes showed very low values, increasing according to the distance from the disinfection plant and higher in summer. In chlorine dioxide-treated samples THMs ranged from <0.01 to 1 μg/L, whereas in chlorine-treated they ranged from 0.3 to 25 μg/L. Brominated THMs were measured at detectable levels in chlorine-treated samples only (range: 0.1–1 μg/L). Chlorite was evidenced in chlorine dioxide-treated samples only (range: 21–290 μg/L). Chlorate was measured in samples collected from all water networks (range: 2–276 μg/L). Conclusions: Neither chlorine nor chlorine dioxide form THMs at high levels in our samples; this is due to source water, which contains very low levels of organic substance even in case of surface water. Chlorite, produced by chlorine dioxide only, deserves attention as little information is available on its chemical reactions and fate in drinking water within water systems. More important to be investigated is the presence of chlorate, unexpectedly present in several water samples whatever disinfection treatment is used.