scholarly journals Arsenic in Pteris vittata is localized to the cell wall in a water-soluble state

Author(s):  
Kazuki Sugawara ◽  
Hiroshi Hayashi ◽  
Chihiro Inoue

Abstract Pteris vittata L., a hyperaccumulator of As, has great potential in environmental remediation. Localization analysis of As and Ca, K, S, and P in arsenic-exposed and unexposed P. vittata pinnae was performed using an electron probe micro analyzer. A comparison of section preparation methods revealed that the As in P. vittata is water-soluble and not tightly bound to the tissue. Further elemental mapping revealed that the localization of S was not consistent with that of As. Therefore, the formation of a complex of low-molecular-weight thiols and As, which is a common detoxification mechanism in plants, may be a limited in P. vittata. It was confirmed that As was localized around the cell wall when the cell was in a healthy state, and that the distribution of As expanded to the whole cell when the cell was damaged. These results suggest that P. vittata may retain As extracellularly to inhibit damage to healthy cells. However, in the periphery of pinnae, which is more susceptible to damage, As was distributed throughout the cell, eventually leading to browning.

2014 ◽  
Vol 5 ◽  
pp. 658-666 ◽  
Author(s):  
Difa Xu ◽  
Shaowen Cao ◽  
Jinfeng Zhang ◽  
Bei Cheng ◽  
Jiaguo Yu

Silver chromate (Ag2CrO4) photocatalysts are prepared by microemulsion, precipitation, and hydrothermal methods, in order to investigate the effect of preparation methods on the structure and the visible-light photocatalytic activity. It is found that the photocatalytic activity of the prepared Ag2CrO4was highly dependent on the preparation methods. The sample prepared by microemulsion method exhibits the highest photocatalytic efficiency on the degradation of methylene blue (MB) under visible-light irradiation. The enhanced photocatalytic activity could be ascribed to the smaller particle size, higher surface area, relatively stronger light absorption, and blue-shift absorption edge, which result in the adsorption of more MB molecules, a shorter diffusion process of more photogenerated excitons, and a stronger oxidation ability of the photogenerated holes. Considering the universalities of microemulsion, precipitation, and hydrothermal methods, this work may also provide a prototype for the comparative study of semiconductor based photocatalysis for water purification and environmental remediation.


2017 ◽  
Vol 239 ◽  
pp. 204-210 ◽  
Author(s):  
C. Safi ◽  
L. Cabas Rodriguez ◽  
W.J. Mulder ◽  
N. Engelen-Smit ◽  
W. Spekking ◽  
...  

2015 ◽  
Vol 5 (4) ◽  
pp. 9-15
Author(s):  
Thanh Long Nguyen ◽  
Quang Luan Le

The mixtures β-glucan extracted from the yeast cell wall were irradiated under gamma rays from a Co-60 source at doses of 100, 200 and 300 kGy in order to prepare water-soluble β-glucan. Yields of the water soluble β-glucan produced are 25.9, 49.1, 66.71%, and their molecular weights (Mw) are 30.5, 24.9 and 10.8 kDa, respectively. There are no any new peak in the IR spectra of the irradiated β-glucan samples, but the intensity ratio between the peaks at wavenumber of 1156 cm-1 (assigned to C-O-C bond) and of 1040 cm-1 (assigned to C-C bond) in glycosidic linkages was reduced with irradiation dose. These results revealed that gamma irradiation did not cause any change in the β-glucan structure except the scissions of glycosidic linkages. In this study, immuno stimulation of the irradiated b-glucan was also investigated for the Swiss mice. After 28 days supplying with the irradiated b-glucan, not only cellular indexes (white blood cell, neutrophils and lymphocytes counts), but also humoral  immunity indexes (IgA and IgM) of the mice significantly increased and the highest effects was obtained for the mice supplied with the oligoβ-glucan prepared by gamma irradiation at 200 kGy. Thus, the water soluble oligoβ-glucan with Mw ~ 24.9 kDa prepared by gamma radiation much stimulated the natural immune system (non-specific immunity) in mice including both the cellular and humoral immunities. Particularly, the irradiated b-glucan is a very promising product for preparation of functional foods aiming at cancer prevention.


2000 ◽  
Vol 104 (5) ◽  
pp. 603-610 ◽  
Author(s):  
O. Ahrazem ◽  
B. Gómez-Miranda ◽  
A. Prieto ◽  
I. Barasoaín ◽  
M. Bernabé ◽  
...  

1971 ◽  
Vol 125 (2) ◽  
pp. 473-480 ◽  
Author(s):  
M. A. Obaidah ◽  
K. W. Buck

1. The nature of two polysaccharides (s020 values 6S and 2S respectively in 1m-sodium hydroxide), comprising a fragment (fraction BB, [α]D +236° in 1m-sodium hydroxide), previously isolated from cell walls of Fusicoccum amygdali, has been investigated. 2. Both the major (2S) and minor (6S) components were affected by incubation with α-amylase. The 6S polysaccharide was also attacked by exo-β-(1→3)-glucanase, which is evidence that it contained both α-(1→4)- and β-(1→3)-glucopyranose linkages. By fractionation of the products of α-amylase-treated fraction BB it was possible to obtain a water-insoluble polysaccharide, fraction P ([α]D +290° in 1m-sodium hydroxide, 67% of fraction BB) and a water-soluble polysaccharide, fraction Q ([α]D +16° in 1m-sodium hydroxide, 11% of fraction BB), both of which sedimented as single boundaries with s020 values (in 1m-sodium hydroxide) of 1.7S and 4.6S respectively. 3. Evidence from periodate oxidation, methylation analysis, i.r. spectroscopy and partial acid hydrolysis showed that fraction P consisted of linear chains of α-(1→3)-glucopyranose units with blocks of one or two α-(1→4)-glucopyranose units interspersed at intervals along the main chain. The 2S polysaccharide, from which fraction P is derived, evidently also contains longer blocks of α-(1→4)-glucopyranose units, that are susceptible to α-amylase action. 4. Fraction Q consisted of glucose (88%) with small amounts of galactose, mannose and rhamnose. Evidence from digestion with exo- and endo-β-(1→3)-glucanases, periodate oxidation and methylation analysis suggests that fraction Q consists of a branched galactomannorhamnan core, to which is attached a β-(1→3)-, β-(1→6)-glucan. In the cell wall, chains of α-(1→4)-linked glucopyranose units are linked to fraction Q to form the 6S component of fraction BB.


Biomolecules ◽  
2019 ◽  
Vol 9 (8) ◽  
pp. 319 ◽  
Author(s):  
Liu ◽  
Liang ◽  
Jiang ◽  
Chen

The juice sacs of pummelo fruit is susceptible to softening during storage at 25 °C, which causes quality deterioration and flavor loss during postharvest pummelo storage. This study investigated the changes in metabolisms of antioxidant and cell wall in juice sacs of three pummelo cultivars—Hongroumiyou (HR), Bairoumiyou (BR) and Huangroumiyou (HuR)—during postharvest storage. The results revealed that, with the extension of storage, the juice sacs of three pummelo cultivars exhibited a decrease in total antioxidant capacity (TAC), DPPH and ABTS radical scavenging activity; a decline in total phenols (TP) content and an increase firstly then a decrease in total ascorbic acid (TAA) content; and a decrease in lipoxygenase (LOX) activity and a rise initially, but a decline in activities of ascorbate peroxidase (APX) and glutathione peroxidase (GPX). Additionally, increased water-soluble pectin (WSP), but declined propectin, ionic-soluble pectin (ISP) and chelator-soluble pectin (CSP); as well as an increase from 0 d to 60 d then followed by a decline in activities of pectinesterase (PE), polygalacturonase (PG) and pectate lyase (PL) were observed. These results suggested that the metabolisms of antioxidant and cell wall could result in softening and senescence of pummelo fruit.


2017 ◽  
Vol 38 (SI 2 - 6th Conf EFPP 2002) ◽  
pp. 617-619 ◽  
Author(s):  
A. Šrobárová ◽  
G. Kogan ◽  
L. Tamas ◽  
E. Machová

Most of the experiments carried out in the area of plant protection have used chitin and chitosan obtained from the crustacean chitin which production is rather expensive. In our study we have applied the chitin-glucan complex prepared from the waste mycelia of filamentous fungi, from baker’s yeast. Five different polysaccharides have been used for the preparation of water-soluble compounds and the assay of their antifungal activity against plant pathogen Fusarium oxysporum. In the field experiments, application of the polysaccharides led to the diminished infestation as well as to significantly increased productivity of fresh weight of the plants (tomato). The results demonstrated that application of the polysaccharides led to increased production of cell wall and some outher and intermembrane-bound proteins. Although the nature of the observed proteins has not been yet established, it can be speculated that they represent some enzymes involved in the antiinfective defense mechanisms in plants.


2019 ◽  
Vol 125 (3) ◽  
pp. 459-469 ◽  
Author(s):  
María González-Hourcade ◽  
Marcia R Braga ◽  
Eva M del Campo ◽  
Carmen Ascaso ◽  
Cristina Patiño ◽  
...  

Abstract Background and Aims One of the most distinctive features of desiccation-tolerant plants is their high cell wall (CW) flexibility. Most lichen microalgae can tolerate drastic dehydration–rehydration (D/R) conditions; however, their mechanisms of D/R tolerance are scarcely understood. We tested the hypothesis that D/R-tolerant microalgae would have flexible CWs due to species-specific CW ultrastructure and biochemical composition, which could be remodelled by exposure to cyclic D/R. Methods Two lichen microalgae, Trebouxia sp. TR9 (TR9, adapted to rapid D/R cycles) and Coccomyxa simplex (Csol, adapted to seasonal dry periods) were exposed to no or four cycles of desiccation [25–30 % RH (TR9) or 55–60 % RH (Csol)] and 16 h of rehydration (100 % RH). Low-temperature SEM, environmental SEM and freeze-substitution TEM were employed to visualize structural alterations induced by D/R. In addition, CWs were extracted and sequentially fractionated with hot water and KOH, and the gel permeation profile of polysaccharides was analysed in each fraction. The glycosyl composition and linkage of the main polysaccharides of each CW fraction were analysed by GC–MS. Key Results All ultrastructural analyses consistently showed that desiccation caused progressive cell shrinkage and deformation in both microalgae, which could be rapidly reversed when water availability increased. Notably, the plasma membrane of TR9 and Csol remained in close contact with the deformed CW. Exposure to D/R strongly altered the size distribution of TR9 hot-water-soluble polysaccharides, composed mainly of a β-3-linked rhamnogalactofuranan and Csol KOH-soluble β-glucans. Conclusions Cyclic D/R induces biochemical remodelling of the CW that could increase CW flexibility, allowing regulated shrinkage and expansion of D/R-tolerant microalgae.


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