Uranium in the Environment: Occurrence, Transfer, and Biological Effects

Ribera, D.; Labrot, F.; Tisnerat, Gérard; Narbonne, Jean‐François

doi:10.1007/978-1-4613-8478-6_3

Cited by 74 publications

(78 citation statements)

References 53 publications

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“…Its radiotoxicity is of minor ecological relevance compared to its toxicity due to chemical interference with metabolism (1,2). The latter is caused mostly by the displacement of Ca 2ϩ and Mg 2ϩ from functionally important binding sites in enzymes (3).…”

mentioning

confidence: 99%

Mechanism of Attenuation of Uranyl Toxicity by Glutathione in Lactococcus lactis

Obeid

Oertel

Solioz

et al. 2016

Appl Environ Microbiol

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b ABSTRACTBoth prokaryotic and eukaryotic organisms possess mechanisms for the detoxification of heavy metals, and these mechanisms are found among distantly related species. We investigated the role of intracellular glutathione (GSH), which, in a large number of taxa, plays a role in protection against the toxicity of common heavy metals. Anaerobically grown Lactococcus lactis containing an inducible GSH synthesis pathway was used as a model organism. Its physiological condition allowed study of putative GSH-dependent uranyl detoxification mechanisms without interference from additional reactive oxygen species. By microcalorimetric measurements of metabolic heat during cultivation, it was shown that intracellular GSH attenuates the toxicity of uranium at a concentration in the range of 10 to 150 M. In this concentration range, no effect was observed with copper, which was used as a reference for redox metal toxicity. At higher copper concentrations, GSH aggravated metal toxicity. Isothermal titration calorimetry revealed the endothermic binding of U(VI) to the carboxyl group(s) of GSH rather than to the reducing thiol group involved in copper interactions. The data indicate that the primary detoxifying mechanism is the intracellular sequestration of carboxyl-coordinated U(VI) into an insoluble complex with GSH. The opposite effects on uranyl and on copper toxicity can be related to the difference in coordination chemistry of the respective metal-GSH complexes, which cause distinct growth phase-specific effects on enzyme-metal interactions. IMPORTANCEUnderstanding microbial metal resistance is of particular importance for bioremediation, where microorganisms are employed for the removal of heavy metals from the environment. This strategy is increasingly being considered for uranium. However, little is known about the molecular mechanisms of uranyl detoxification. Existing studies of different taxa show little systematics but hint at a role of glutathione (GSH). Previous work could not unequivocally demonstrate a GSH function in decreasing the presumed uranyl-induced oxidative stress, nor could a redox-independent detoxifying action of GSH be identified. Combining metabolic calorimetry with cell number-based assays and genetics analysis enables a novel and general approach to quantify toxicity and relate it to molecular mechanisms. The results show that GSH-expressing microorganisms appear advantageous for uranyl bioremediation.T he natural abundance of uranium and the increasing health risks that originate from its anthropogenic release to the environment have generated a high demand for understanding the molecular mechanisms of uranium toxicity. Its radiotoxicity is of minor ecological relevance compared to its toxicity due to chemical interference with metabolism (1, 2). The latter is caused mostly by the displacement of Ca 2ϩ and Mg 2ϩ from functionally important binding sites in enzymes (3). The water-soluble uranyl cation UO 2 2ϩ is the most commonly found contaminant, which contains uranium in its highest ...

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mentioning

confidence: 99%

Mechanism of Attenuation of Uranyl Toxicity by Glutathione in Lactococcus lactis

Obeid

Oertel

Solioz

et al. 2016

Appl Environ Microbiol

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“…Generally, animal foodstuffs accumulate less uranium, but higher concentrations can be found in shellfish and fish, that accumulate more uranium than the terrestrial animals (Ribera et al, 1996;WHO, 2001;Anke et al, 2009).…”

Section: Literature Datamentioning

confidence: 99%

Uranium in foodstuffs, in particular mineral water

2009

EFS2

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“…Due to the high affinity of heavy metals with sediments, the latter can represent an important storage compartment. This is particularly true for U [3]. In French rivers, U concentrations in sediments range between 0.24 and 6.29 µg U/g dry wt [1].…”

Section: Introductionmentioning

confidence: 98%

Sublethal effects of sediment-associated uranium on Chironomus riparius (Diptera: Chironomidae) larvae

Dias¹,

Ksas²,

Camilleri³

et al. 2005

Radioprotection

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Abstract. In aquatic ecosystems, sediments constitute a reservoir for many of the most persistent chemicals that are introduced into surface waters. Sediments provide a habitat for various benthic macroinvertebrates, which could be exposed to sediment-associated chemicals both directly and via food intake. These organisms play an important role on the structure and the functioning of aquatic ecosystems. Among the non-biologically essential metals, data concerning uranium (U) fate and effects on freshwater benthic macroinvertebrates are sparse. The present study aimed at estimating effects of a chronic U exposure on Chironomus riparius larvae. To achieve this goal, a 10-d laboratory bioassay was performed exposing, via the sediment, first instar larvae to a gradient of U concentrations (0, 2.97, 6.07, 11.44, 23.84 µg U/g dry wt). Significant negative effects on mortality, development time and growth were detected at 6.07, 6.07 and 2.97 µg U/g dry wt, respectively. The results underlined a possible impact of U at the population level at environmentally occurring U concentrations. This study confirmed the need for more research on the role of U on benthic macroinvertebrate.

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Uranium in the Environment: Occurrence, Transfer, and Biological Effects

Cited by 74 publications

References 53 publications

Mechanism of Attenuation of Uranyl Toxicity by Glutathione in Lactococcus lactis

Mechanism of Attenuation of Uranyl Toxicity by Glutathione in Lactococcus lactis

Uranium in foodstuffs, in particular mineral water

Sublethal effects of sediment-associated uranium on Chironomus riparius (Diptera: Chironomidae) larvae

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