Detoxification processes from vanadate at the root apoplasm activated by caffeic and polygalacturonic acids

In the root apoplasm, V(V) and V(IV) toxicity can be alleviated through redox and complexation reactions involving phenolic substances and the polyuronic components. In such context we report the role of polygalacturonic acid (PGA) on the reducing activity of caffeic acid (CAF) towards V(V). The redox reaction was particularly effective at pH 2.8 leading to the formation of oxidation products with redox activity towards V(V). An o-quinone was identified as the first product of the reaction which is further involved in the formation of CAF dimers. At pH ≥ 3.6 the redox activity decreased and a yield in V(IV) equal to 38, 31, 21 and 14% was found at pH 3.6, 4.0. 5.0 and 6.0 respectively compared with that obtained at pH 2.8. The redox reaction was faster in the presence of PGA and a higher yield of V(IV) was found in the 4.0–6.0 pH range with respect to the CAF-V(V) binary system. The higher efficiency of the redox reaction in the presence of PGA was related with the ability of PGA to bind V(IV). The biological significance of the redox reaction between CAF and V(V), as well as the role of PGA in such reaction, was established “in vivo” using triticale plants. Results showed that PGA reduced significantly the phytotoxic effects of the V(V)-CAF system.In the root apoplasm, V(V) and V(IV) toxicity can be alleviated through redox and complexation reactions involving phenolic substances and the polyuronic components. In such context we report the role of polygalacturonic acid (PGA) on the reducing activity of caffeic acid (CAF) towards V(V). The redox reaction was particularly effective at pH 2.8 leading to the formation of oxidation products with redox activity towards V(V). An o-quinone was identified as the first product of the reaction which is further involved in the formation of CAF dimers. At pH - 3.6 the redox activity decreased and a yield in V(IV) equal to 38, 31, 21 and 14% was found at pH 3.6, 4.0. 5.0 and 6.0 respectively compared with that obtained at pH 2.8. The redox reaction was faster in the presence of PGA and a higher yield of V(IV) was found in the 4.0-6.0 pH range with respect to the CAF-V(V) binary system. The higher efficiency of the redox reaction in the presence of PGA was related with the ability of PGA to bind V(IV). The biological significance of the redox reaction between CAF and V(V), as well as the role of PGA in such reaction, was established "in vivo" using triticale plants. Results showed that PGA reduced significantly the phytotoxic effects of the V(V)-CAF system. © 2015 Garau et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited

Adult urinary bladder tumors with rabdomyosarcomatous differentiation: Clinical, pathological and immunohistochemical studies

Adult rhabdomyosarcoma (RMS) in the urinary bladder is rare, and is the subject of case reports and small series. It consists of sheets of small round blue cells with high nuclear cytoplasmic ratio, brisk mitosis and apoptosis. In this study, we reported one case of pure rhabdomyosarcoma and two cases of urothelial carcinomas with extensive rhabdomyosarcomatous differentiation. In addition, their immunohistochemical profile was compared to that of small cell carcinoma of the bladder. Our study showed that sufficient sampling was critical for the diagnosis of urothelial carcinoma with extensive rhabdomyosarcomatous differentiation. As adult RMS in the bladder and urothelial carcinoma with rhabdomyosarcomatous differentiation shared morphological features with small cell carcinoma of the bladder, appropriate immunohistochemical stains were necessary in the differential diagnosis. We showed both rhabdomyosarcoma and rhabdomyosarcomatous areas of the urothelial carcinoma were positive for myogenin, negative for cytokeratin and chromogranin stains. In contrast, small cell carcinoma was positive for cytokeratin, and 7 out of 9 cases were also positive for chromogranin. Both rhabdomyosarcoma and small cell carcinoma could be positive for synaptophysin, a potential pitfall to avoid. In addition, all of the tumors with rhabdomyosarcomatous differentiation were negative for FKHR rearrangement

Influenza dell’acido caffeico nell’assorbimento dell’As(V) da parte dei poliioni di Fe(III) intrappolati nelle strutture poliuroniche dell’apoplasma radicale.

L’acido Caffeico assorbito su Fe(III)-pectati influenza l’assorbimento dell’arseniato

Cooperative effect of root exudates on the toxicity of Cu(II) ions towards plants

Copper is a structural and catalytic component of many redox enzymes like plastocyanin, oxidases, laccases, and dismutases and is therefore considered an essential element for plants. However, accumulation of toxic levels of copper in soil has become an increasing problem since its absorption by plants in amounts higher than certain threshold can cause structural damages or inhibit enzymatic activities with consequent alterations of cellular metabolism. Much of the Cu(II) accumulates within roots where it is strongly bound to cell walls and can be displaced by similar cations e.g. Pb(II) or by different organic ligands.To verify the role of certain cell wall components and of selected organic aliphatic and/or aromatic acids commonly occurring in root exudates on Cu(II) availability for plants, we studied several systems made up by Cu(II), polygalacturonic, malic and caffeic acids at pH 5.8 in the presence of 1 mM CaCl2. Our results indicate a high capacity of polygalacturonic acid (PGA) to bind Cu(II) and a high redox activity of caffeic acid towards Cu(II). The spectrophotometric data indicate that Cu(II) ions interact with caffeic acid (CAF) to form a CAF‐Cu(II) complex where Cu(II) is reduced to Cu(I) through an inner‐sphere electron transfer. The redox activity is strongly influenced by the presence of malic acid which shows a higher affinity towards Cu(II) stabilizing it in its higher oxidation state. Contrarily to CAF, malic acid was able to mobilize Cu(II) from PGA. To verify the importance of such reactions on Cu(II) phytotoxicity we performed different plant growth experiments using triticale (x Triticosecale Wittmack). Preliminary results indicate that PGA and with a lesser extent CAF reduce Cu(II) phytotoxicity

Role of polygalacturonic acid and the cooperative effect of caffeic andmalic acids on the toxicity of Cu(II) towards triticale plants (× Triticosecale Wittm)

In this study, we investigated the cooperative effect of caffeic (CAF) and malic (MAL) acids as well as the role of polygalacturonic acid (PGA) on the toxicity of copper (Cu)(II) towards triticale plants (× Triticosecale Wittm.). Plant growth experiments carried out in hydroponic solutions at pH 6.0 revealed that CAF and PGA, but not MAL, were quite effective at reducing Cu(II) phytotoxicity and that MAL addition abolished the positive effects of CAF. The study of the CAFCu(II) system in aqueous solution clearly indicated that the lower toxicity of Cu(II) in the presence of CAF was due to the occurrence of a redox reaction between CAF and Cu(II), while the phytotoxicity recorded in the Cu(II)-CAF-MAL system was attributed to a competitive effect of MAL in the Cu(II) complexation by CAF, which ultimately reduced the redox activity. The lowest Cu(II) phytotoxicity recorded in the presence of PGA was attributed to the high affinity of the polysaccharidic matrix towards the metal ion. The results from this study shed new light on the Cu(II)-detoxifying action of selected root exudates and highlight the negative cooperation of MAL on the Cu(II)-detoxifying activity by CAF

Effect of Municipal Solid Waste Compost on Antimony Mobility, Phytotoxicity and Bioavailability in Polluted Soils

The effect of a municipal solid waste compost (MSWC), added at 1 and 2% rates, on the mobility, phytotoxicity, and bioavailability of antimony (Sb) was investigated in two soils (SA: acidic soil; SB: alkaline soil), spiked with two Sb concentrations (100 and 1000 mg kg(-1)). The impact of MSWC on microbial activity and biochemical functioning within the Sb-polluted soils was also considered. MSWC addition reduced water-soluble Sb and favored an increase in residual Sb (e.g., by 1.45- and 1.14-fold in SA-100 and SA-1000 treated with 2% MSWC, respectively). Significant increases in dehydrogenase activity were recorded in both the amended soils, as well as a clear positive effect of MSWC on the metabolic activity and catabolic diversity of respective microbial communities. MSWC alleviated Sb phytotoxicity in triticale plants and decreased Sb uptake by roots. However, increased Sb translocation from roots to shoots was recorded in the amended soils, according to the compost rate. Overall, the results obtained indicated that MSWC, particularly at a 2% rate, can be used for the recovery of Sb-polluted soils. It also emerged that using MSWC in combination with triticale plants can be an option for the remediation of Sb-polluted soils, by means of assisted phytoextraction

Role of caffeic acid on the As(V) sorption by a ferrihydrite coated with a Ca‐polygalacturonate network

Iron oxy‐hydroxides in soil are known to have a high affinity for As(V) inorganic species. At the soil‐root interface such mineral components are embedded by mucilaginous material which is secreted from continuously growing root cap cells. In order to determine the role of plant mucilages on the As(V) sorption by iron oxy‐hydroxides, we layered a Ca‐polygalacturonate network (CaPGA) on amorphous iron(III) hydroxides (ferrihydrite) particles. The scanning electron micrographs (SEM) of the CaPGA network coating the ferrihydrite (Fer‐CaPGA) show a regular structure with a honeycomb‐like pattern where interlacing fibrils form a porous system. FT‐IR spectra of Fer‐CaPGA indicate that CaPGA fibrils are retained by the surficial Fe(III) nuclei of Fer through electrostatic interactions. The sorption experiments, carried out at pH 4.3 and 5.8 in the presence of CaPGA, show a lower amount of As(V) sorbed with respect to Fer alone, being lower after 3 and 24 hours of reaction by about 70 and 30%, respectively. This was mainly attributed to a barrier effect exerted by the PGA gel rather than the occlusion of Fer micropores by the polysaccharidic chains. The simultaneous sorption kinetics of As(V) and caffeic acid (CAF) by Fer show that As(V) sorption is almost independent by CAF concentration indicating a higher affinity of arsenate ions towards Fer surfaces. However, the amount of As(V) sorbed by the Fer‐CaPGA, in the presence of 0.25, 0.5 and 1.0 mM CAF, is markedly lower of about 20, 25 and 40 % respectively than that found in As(V)‐CAF‐Fer ternary systems. This suggests a different ability of CAF and As(V) to cross the CaPGA network, although chemical reactions involving CAF and the surficial Fe(III) nuclei of Fer could have a role, as suggested by FT‐IR spectra, in restricting As(V) sorption

Connecting biodiversity and potential functional role in modern euxinic environments by microbial metagenomics

14 páginas, 7 figuras, 3 tablas.Stratified sulfurous lakes are appropriate environments for studying the links between composition and functionality in microbial communities and are potentially modern analogs of anoxic conditions prevailing in the ancient ocean. We explored these aspects in the Lake Banyoles karstic area (NE Spain) through metagenomics and in silico reconstruction of carbon, nitrogen and sulfur metabolic pathways that were tightly coupled through a few bacterial groups. The potential for nitrogen fixation and denitrification was detected in both autotrophs and heterotrophs, with a major role for nitrogen and carbon fixations in Chlorobiaceae. Campylobacterales accounted for a large percentage of denitrification genes, while Gallionellales were putatively involved in denitrification, iron oxidation and carbon fixation and may have a major role in the biogeochemistry of the iron cycle. Bacteroidales were also abundant and showed potential for dissimilatory nitrate reduction to ammonium. The very low abundance of genes for nitrification, the minor presence of anammox genes, the high potential for nitrogen fixation and mineralization and the potential for chemotrophic CO2 fixation and CO oxidation all provide potential clues on the anoxic zones functioning. We observed higher gene abundance of ammonia-oxidizing bacteria than ammonia-oxidizing archaea that may have a geochemical and evolutionary link related to the dominance of Fe in these environments. Overall, these results offer a more detailed perspective on the microbial ecology of anoxic environments and may help to develop new geochemical proxies to infer biology and chemistry interactions in ancient ecosystems.This research was funded by Grants GOS-LAKES CGL2009-08523-E and DARKNESS CGL2012-32747 to EOC from the Spanish Office of Science (MINECO), from financial support by the Beyster Family Fund of the San Diego Foundation and the Life Technologies Foundation to the J Craig Venter Institute, and the NASA Astrobiology Institute to CLD.Peer reviewe