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

Morelli, Elisabetta; Ferrara, R.; Bellini, Barbara; Dini, Fernando; Giuseppe, Graziano Di; Fantozzi, L.

doi:10.1016/j.scitotenv.2009.09.047

Cited by 37 publications

(42 citation statements)

References 53 publications

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“…This was confirmed by the fact that HgGS 2 and HgPC 2 , as well as PC 4 , were observed when the fraction was determined using MALDI-TOF-MS (Figure 4(b)). Previous studies also showed that some water plants (Hydrilla verticillata and Vallisneria spiralis L. [17]), a microalga (Thalassiosira weissflogii [28]) as well as some terrestrial plants (Brassica napus [29] and Brassica chinensis L. [30]) can produce PCs under the exposure to Hg.…”

Section: Transformation Of Hg Inside P Tricornutummentioning

confidence: 93%

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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Section: Transformation Of Hg Inside P Tricornutummentioning

confidence: 93%

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

et al. 2012

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“…[44][45][46] However at lower Hg concentrations and longer exposure time, PCs do not seem to have a noticeable role in diatoms. [41] Therefore PCs role in Hg detoxification under environmentally relevant conditions remains to be confirmed.…”

Section: Mercury Intracellular Transformationsmentioning

confidence: 98%

“…[43] Reduction and demethylation of Hg are other intracellular transformations observed for both phytoplankton and macrophytes.Algal Hgreduction rates were shown to depend on exposure concentrations, but not on the light conditions. [44,45] The diatom T. weissflogii exposed to 5 nM Hg II produced comparable amount of Hg 0 in the light and in the dark conditions. [45] The mechanisms by which primary producers reduce Hg are still to be elucidated.…”

Section: Mercury Intracellular Transformationsmentioning

confidence: 99%

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Towards Mechanistic Understanding of Mercury Availability and Toxicity to Aquatic Primary Producers

Dranguet¹,

Flück²,

Regier³

et al. 2014

Chimia

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The present article reviews current knowledge and recent progress on the bioavailability and toxicity of mercury to aquatic primary producers. Mercury is a ubiquitous toxic trace element of global concern. At the base of the food web, primary producers are central for mercury incorporation into the food web. Here, the emphasis is on key, but still poorly understood, processes governing the interactions between mercury species and phytoplankton, and macrophytes, two representatives of primary producers. Mass transfer to biota surface, adsorption to cell wall, internalization and release from cells, as well as underlying toxicity mechanisms of both inorganic mercury and methylmercury are discussed critically. In addition, the intracellular distribution and transformation processes, their importance for mercury toxicity, species-sensitivity differences and trophic transfer are presented. The mini-review is illustrated with examples of our own research.

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“…For example, phytoplankton can produce antioxidant enzymes to scavenge reactive oxygen species, which are overproduced due to stress under Cd exposure, such as superoxide dismutase, catalase, and ascorbate peroxidase (Pinto et al 2003). Additionally, some species are able to synthesize glutathione (GSH) and other non-protein thiol peptides to reduce cytotoxicity as a result of exposure to Cd (Morelli and Pratesi 1997;Kawakami et al 2006;Morelli et al 2009). …”

mentioning

confidence: 99%

The response and detoxification strategies of three freshwater phytoplankton species, Aphanizomenon flos-aquae, Pediastrum simplex, and Synedra acus, to cadmium

Ran

Yue

et al. 2015

Environ Sci Pollut Res

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The response and detoxification mechanisms of three freshwater phytoplankton species (the cyanobacterium Aphanizomenon flos-aquae, the green alga Pediastrum simplex, and the diatom Synedra acus) to cadmium (Cd) were investigated. The cell growth of each species was measured over 10 days, and chlorophyll a fluorescence, Cd bioaccumulation (including surface-adsorbed and intracellular Cd), and phytochelatin (PC) synthesis were determined after 96-h exposures. The growth of the three phytoplankton species was significantly inhibited when Cd concentrations were ≥5 mg L(-1). Compared with P. simplex, greater growth inhibition in S. acus and A. flos-aquae occurred. The changes in chlorophyll fluorescence parameters including the maximal quantum yield of PSII (Fv/Fm) and relative variable fluorescence of the J point (Vj) demonstrated that the increase in Cd concentration damaged PSII in all three species. After 96-h exposures, the accumulation of surface-adsorbed Cd and intracellular Cd increased significantly in all three species, with the increase of Cd concentrations in the media; total cadmium accumulation was 245, 658, and 1670 times greater than that of the control in A. flos-aquae, P. simplex, and S. acus, respectively, after exposure to 10 mg L(-1). Total thiols exhibited a similar trend to that of Cd accumulation. PC3 was found in A. flos-aquae and P. simplex in all Cd treatments. Glutathione (GSH) and PC2 were also produced in response to exposure to high concentrations of Cd. PC4 was only discovered at exposure concentrations of 10 mg L(-1) Cd and only in S. acus. The intracellular Cd/PCs ratio increased in all three phytoplankton with an increase in Cd concentrations, and a linear relationship between the ratio and the growth inhibition rates was observed with P. simplex and S. acus. Our results have demonstrated that metal detoxification mechanisms were dependent on the species. This study suggested that the variance of metal detoxification strategies, such as cadmium accumulation and PCs, might be an explanation why algal species have different sensitivity to Cd at various levels.

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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

Cited by 37 publications

References 53 publications

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

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

Towards Mechanistic Understanding of Mercury Availability and Toxicity to Aquatic Primary Producers

The response and detoxification strategies of three freshwater phytoplankton species, Aphanizomenon flos-aquae, Pediastrum simplex, and Synedra acus, to cadmium

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