Role of glutathione and phytochelatin in Hydrilla verticillata (I.f.) royle and Valusneria spiraus L. under mercury stress

Gupta, Meetu; Tripathi, Rudra Deo; Rai, Umesh; Prakāsh, Chandra

doi:10.1016/s0045-6535(98)00073-3

Cited by 94 publications

(62 citation statements)

References 26 publications

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“…Howe and Merchant (1992), in a study examining the ability of the green microalga Chlamydomonas reinhardtii to produce metalbinding peptides in response to Cd, Hg or Ag, reported that Hg-treated cells exhibited a transient but striking increase in glutathione levels, but were not able to accumulate measurable amounts of PCs. Recently, much more information has become available on the effects of Hg on the non-protein thiol pool in plants (Gupta et al, 1998;Iglesia-Turino et al, 2006;Israr et al, 2006;Rellan-Alvarez et al, 2006). Among these authors, general agreement on the involvement of glutathione in Hg detoxification can be observed.…”

Section: Discussionmentioning

confidence: 93%

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Changes in the non-protein thiol pool and production of dissolved gaseous mercury in the marine diatom Thalassiosira weissflogii under mercury exposure

Morelli

Ferrara

Bellini

et al. 2009

Science of The Total Environment

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Two detoxification mechanisms working in the marine diatom Thalassiosira weissfloggii to cope with mercury toxicity were investigated. Initially, the effect of mercury on the intracellular pool of non-protein thiols was studied in exponentially growing cultures exposed to sub-toxic HgCl 2 concentrations. T. weissfloggii cells responded by synthesizing metalbinding peptides, named phytochelatins (PCs), besides increasing the intracellular pool of glutathione and γ-glutamylcysteine (γ-EC). Intracellular Hg and PC concentrations increased with the Hg concentration in the culture medium, exhibiting a distinct dose-response relationship. However, considerations of the PCs-SH:Hg molar ratio suggest that also glutathione could be involved in the intracellular mercury sequestration. The time course of the non-protein thiol pool and Hg intracellular concentration shows that PCs, glutathione and γ-EC represent a rapid cellular response to mercury, although their role in Hg detoxification seems to lose importance at longer incubation times. The occurrence of a process of reduction of Hg(II) to Hg° and subsequent production of dissolved gaseous mercury (DGM) was also investigated at lower Hg concentrations, at which the PC synthesis doesn't seem to be involved. The significant (P<0.01) correlation between the cellular density in solution and the production of DGM suggests that this diatom is capable of directly producing DGM, both in light and dark conditions. This finding has been confirmed by the absence of DGM production in the culture media containing formaldehyde-killed cells. Finally, the relationship between these two different pathways of Hg detoxification is discussed.

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Section: Discussionmentioning

confidence: 93%

“…Among these authors, general agreement on the involvement of glutathione in Hg detoxification can be observed. Only one paper (Gupta et al, 1998) reports that, besides glutathione, PCs can play a role in the Hg cellular sequestration in two species of aquatic plants.…”

Section: Discussionmentioning

confidence: 99%

Changes in the non-protein thiol pool and production of dissolved gaseous mercury in the marine diatom Thalassiosira weissflogii under mercury exposure

Morelli

Ferrara

Bellini

et al. 2009

Science of The Total Environment

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“…Although PCs have already been impli cated into mer cury toler ance (Zenk, 1996), stud ies of mer cury seques tra tion by PCs are very scarce. Gupta et al (1998) showed that two aquatic plants (Hy ril la ver ti cil la ta) and rooted (Val lis ne ria spi ra lis) syn the sized dif fer ent spe cies of phy to chel a tins, dur ing mer cury expo sure. These stud ies are rel e vant to under stand the role that phy to chela tins play in mer cury detox i fi ca tion.…”

Section: Introductionmentioning

confidence: 99%

Mercury intracellular partitioning and chelation in a salt marsh plant, Halimione portulacoides (L.) Aellen: Strategies underlying tolerance in environmental exposure

et al. 2009

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In the pres ence of metal stress, plants can resort to a series of tol er ance mech a nisms. There fore field studies should be under taken in order to eval u ate the real role of these mech a nisms in stress cop ing. The aim of this paper was to clar ify the bio chem i cal pro cesses behind mer cury tol er ance in Ha lim i one por tu la co ides (L.) Ael len (Caryo phyll ales: Cheno po di a ceae) col lected in a mer cury con tam i nated salt marsh. Dif fer ent frac tions of mer cury were sep a rated: buffer-sol u ble (mainly cyto solic) and insol u ble mer cury (mainly asso ci ated with mem branes and cell walls). The amounts in each frac tion of metal were com pared and related to metal dis tribu tion within plant organs. Pro tein-mer cury com plexes were iso lated and ana lysed for their thiol con tent in order to assess wether the tol er ance of this salt marsh plant was asso ci ated with the induc tion of metal che lation by phy to chel a tins. Over all, the mer cury tol er ance strat e gies of the plant are likely to involve root cell wall immo bi li za tion as a major mech a nism of metal resis tance, rather than metal che la tion in the cyto solic fraction. Nev er the less, phy to chel a tins were dem on strated to che late mer cury under envi ron men tal expo sure.

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“…To investigate the toxicity of HgCl 2 to P. tricornutum, the alga was cultured under exposure to HgCl 2 at different concentrations (20,40,80, 100, 120, 140, 160, 180 and 200 g L -1 ). The 96 h cell numbers were measured to obtain a concentration-inhibition curve of the growth inhibition rate, which was calculated from the cell density determined against HgCl 2 concentration.…”

Section: Hg Ec 50 Towards P Tricornutummentioning

confidence: 99%

“…tricornutum cells exposed to different concentrations of HgCl 2 were collected, resuspended in ice-cold 1 mol L -1 NaOH-0.5% (w/w) NaBH 4 for ultrasonic extraction of their PCs in an ice bath [20]. The homogenates were centrifuged at 20000×g for 15 min at 4C, and then a 500 µL aliquot of the supernatant was subjected to reaction with 50 µL TBP for 10 min to further reduce the disulfide-linkage of the PCs.…”

Section: Hg Ec 50 Towards P Tricornutummentioning

confidence: 99%

Studies of biouptake and transformation of mercury by a typical unicellular diatom Phaeodactylum tricornutum

et al. 2012

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Mercury (Hg) is a toxic heavy metal with its biogeochemical cycling in the ocean depending on the type and behavior of the oceanic microalgae. The present work aimed to evaluate bioaccumulation and transformation of Hg by Phaeodactylum tricornutum, a typical unicellular diatom, when exposed to the extremely high level of Hg in order to understand the possible mechanisms of acute stress response. P. tricornutum can accumulate Hg (its bioaccumulation factor is at 10 4 level), and the 96 h EC 50 was estimated to be 145 g L -1 . The amounts of surface-bound Hg being about 1.2 to 4.8 times higher than those of intracellular Hg under exposure to HgCl 2 (from 20 to 120 g L -1 concentrations) suggested that the cell wall of P. tricornutum is an important "fence" towards Hg. After entering the P. tricornutum cell, Hg underwent transformation in its chemical form via interactions with high molecular weight sulfur-containing proteins (accounting for 68% of the intracellular Hg), and glutathione as well as the induced phytochelatins (PCs) (24% Hg) which alleviated the toxicity of HgCl 2 . In addition, the existence of organic ligands greatly influenced the uptake and transformation behavior of P. tricornutum towards HgCl 2 , especially in the case of cysteine (Cys), which increased the uptake of Hg, but alleviated the toxicity of Hg towards P. tricornutum due to the fact that Cys is an important precursor for the synthesis of PCs inside the cell. The uptake process of Hg by P. tricornutum was in agreement with the Freundlich isotherm, suggesting a typical heterogeneous sorption process. More importantly, we observed the conversion of HgCl 2 into methylmercury inside the P. tricornutum cells and its release into the culture solution using HPLC/CVG-AFS and GC-MS, although the mechanism needs to be further investigated. mercury, methylmercury, P. tricornutum, species transformation, toxicity, phytochelatin Citation:Deng G F, Zhang T W, Yang L M, et al. Studies of biouptake and transformation of mercury by a typical unicellular diatom Phaeodactylum tricornutum. Chin Sci Bull, 2013Bull, , 58: 256265, doi: 10.1007 Microorganisms are able to accumulate heavy metals via both ways of surface-bound sorption and intracellular involvement [1]. The cell walls of microorganisms contain many different functional groups such as amine, carboxyl, hydroxyl, sulfates and phosphates, which interact with heavy metals. Microorganisms can also produce proteins and/or polypeptides such as metallothioneins and other cysteine-rich peptides which complex heavy metals and thus detoxify them in the cells [2]. On the other hand, many kinds of natural and anthropogenic ligands are always present in the aquatic environment, and heavy metals may form complexes with such existing ligands resulting in various chemical species, determining significantly the modes and amounts of the heavy metals to enter into the cells of microorganisms. In addition, some heavy metals may be transformed to methylated compounds by microorganisms [3]. All these accumulation a...

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Role of glutathione and phytochelatin in Hydrilla verticillata (I.f.) royle and Valusneria spiraus L. under mercury stress

Cited by 94 publications

References 26 publications

Changes in the non-protein thiol pool and production of dissolved gaseous mercury in the marine diatom Thalassiosira weissflogii under mercury exposure

Changes in the non-protein thiol pool and production of dissolved gaseous mercury in the marine diatom Thalassiosira weissflogii under mercury exposure

Mercury intracellular partitioning and chelation in a salt marsh plant, Halimione portulacoides (L.) Aellen: Strategies underlying tolerance in environmental exposure

Studies of biouptake and transformation of mercury by a typical unicellular diatom Phaeodactylum tricornutum

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