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A Task Group (TG121) of the International Commission on Radiological Protection (ICRP) Committee 1 was launched in 2021 to study the effects of ionizing radiation in offspring and next generations. In this report, we summarize the evidence of multi- and trans-generational effects in non-human biota species that was discussed at the ICRP workshop entitled "Effects of Ionizing Radiation Exposure in Offspring and Next Generations" in June 2022. Epigenetic changes, including changes in DNA methylation, have been observed in trans- and multi-generational irradiation studies in both plants and animals. There were also reports of changes in offspring survival and reproduction. The reported evidence for altered reproduction is an area of potential concern, due to possible effects at the population or ecosystem level. Different considerations are also discussed regarding non-human biota data, such as transferability of data between different species or extending knowledge to humans, differences in species radiosensitivity, the presence of adaptive responses, and dose reconstruction for exposures that occur across multiple generations. Overall, there is a diverse range of available data of the effects in non-human biota, and it will require careful consideration when incorporating this evidence into the system of radiological protection of humans and of the environment. [ABSTRACT FROM AUTHOR]

The long‐term impacts of radiocontaminants (and the associated risks) for ecosystems are still subject to vast societal and scientific debate while wildlife is chronically exposed to various sources and levels of either environmental or anthropogenic ionizing radiation from the use of nuclear energy. The present study aimed to assess induced phenotypical responses in both male and female gammarids after short‐term continuous γ‐irradiation, acting as a typical well‐characterized genotoxic stressor that can interact directly with living matter. In particular, we started characterizing the effects using standardized measurements for biological effects on few biological functions for this species, especially feeding inhibition tests, molting, and reproductive ability, which have already been proven for chemical substances and are likely to be disturbed by ionizing radiation. The results show no significant differences in terms of the survival of organisms (males and females), of their short‐term food consumption which is linked to the general health status (males and females), and of the molting cycle (females). In contrast, exposure significantly affected fecundity (number of embryos produced) at the highest dose rates for irradiated females (51 mGy h–1) and males (5 and 51 mGy h–1). These results showed that, in gammarids, reproduction, which is a critical endpoint for population dynamics, is the most radiosensitive phenotypic endpoint, with significant effects recorded on male reproductive capacity, which is more sensitive than in females. Environ Toxicol Chem 2024;43:2071–2079. © 2024 SETAC [ABSTRACT FROM AUTHOR]

In the environment, populations are exposed to different kinds of ionizing radiation. Little is known about their modes of action on non-human species, and whether or not they are similar for alpha, beta and gamma radiations, considered as the reference. In this context, tritium effects (beta emitter) under the form of tritiated water (HTO) were investigated in zebrafish, a common model in toxicology and ecotoxicology with a fully sequenced genome. Experiments were conducted on early life stages, considered to be highly sensitive to pollutants, by exposing eggs to 0.4 mGy/h of HTO until 10 days post fertilization. Tritium internalization was quantified, and effects were investigated using a combined approach of transcriptomic and proteomic analyses. Results highlighted similarities in the biological pathways affected by HTO by both techniques, such as defence response, muscle integrity and contraction, and potential visual alterations. These results correlated well with previous data obtained on earlier developmental stages (1 and 4 dpf). Interestingly, HTO effects were partly overlapping those obtained after gamma irradiation, underlying potential common modes of action. This study, therefore, brought a body of evidence on the effects of HTO observed at the molecular level on zebrafish larvae. Further studies could investigate if the effects persist in adult organisms. • Zebrafish eggs exposed for 7 and 10 days to HTO at 0.4 mGy/h. • Combination of transcriptomic and proteomic analysis was used to assess HTO effects. • Common modulation of genes and proteins was highlighted for several functions. • More pathways were affected by HTO in 10 dpf larvae compared to 7 dpf larvae. • Results align with previous findings on early stages exposed to HTO or gamma irradiation. [ABSTRACT FROM AUTHOR]

Limited knowledge about in vivo non-covalent uranium (U)-protein complexes is largely due to the lack of appropriate analytical methodology. Here, a method for screening and identifying the molecular targets of U was developed. The approach was based on non-denaturing 1D and 2D gel electrophoresis (ND-PAGE and ND-2D-PAGE (using ND-IEF as first dimension previously described)) in conjunction with laser ablation inductively coupled plasma mass spectrometry (LA-ICP MS) for the detection of U-containing proteins. The proteins were then identified by µbore HPLC-Orbitrap MS/MS. The method was applied to the analysis of cytosol of hepatopancreas (HP) of a model U-bioaccumulating organism (Procambarus clarkii). The imaging of uranium in 2D gels revealed the presence of 11 U-containing protein spots. Six protein candidates (i.e. ferritin, glyceraldehyde-3-phosphate dehydrogenase, triosephosphate isomerase, cytosolic manganese superoxide dismutase (Mn-SOD), glutathione S transferase D1 and H3 histone family protein) were then identified by matching with the data base of crustacea Decapoda species (e.g. crayfish). Among them, ferritin was the most important one. This strategy is expected to provide an insight into U toxicology and metabolism. [ABSTRACT FROM AUTHOR]

An off-gel non-denaturing isoelectric focusing (IEF) method was developed to separate uranium-biomolecule complexes from biological samples as a first step in a multidimensional metalloproteomic approach. Analysis of a synthetic uranium-bovine serum albumin complex demonstrated the focusing ability of the liquid-phase IEF method and the preservation of most of the uranium-protein interactions. The developed method was applied to gill cytosol prepared from zebrafish ( Danio rerio) exposed to depleted uranium. The results were compared in terms of resolution, recovery, and protein identities with those obtained by in-gel IEF using an immobilized pH gradient gel strip. [ABSTRACT FROM AUTHOR]

A non-denaturating isoelectric focusing (ND-IEF) gel electrophoresis protocol has been developed to study and identify uranium (U)-protein complexes with laser ablation-inductively coupled plasma mass spectrometry (LA-ICP MS) and electrospray ionization mass spectrometry (ESI-MS). The ND-IEF-LA-ICP MS methodology set-up was initiated using in vitro U-protein complex standards (i.e., U-bovine serum albumin and U-transferrin) allowing the assessment of U recovery to 64.4 ± 0.4 %. This methodology enabled the quantification of U-protein complexes at 9.03 ± 0.23, 15.27 ± 0.36, and 177.31 ± 25.51 nmol U L in digestive gland cytosols of the crayfish, Procambarus clarkii, exposed respectively to 0, 0.12, and 2.5 μmol of waterborne depleted U L during 10 days. ND-IEF-LA-ICP MS limit of detection was 19.3 pmol U L. Elemental ICP MS signals obtained both in ND-IEF electropherograms and in size exclusion chromatograms of in vivo U-protein complexes revealed interactions between U- and Fe- and Cu-proteins. Moreover, three proteins (hemocyanin, pseudohemocyanin-2, and arginine kinase) out of 42 were identified as potential uranium targets in waterborne-exposed crayfish cytosols by microbore reversed phase chromatography coupled to molecular mass spectrometry (µRPC-ESI-MS/MS) after ND-IEF separation. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

The interactions between uranium and four metalloproteins (Apo-HTf, HSA, MT and Apo-EqSF) were investigated using fluorescence quenching measurements. The combined use of a microplate spectrofluorometer and logarithmic additions of uranium into protein solutions allowed us to define the fluorescence quenching over a wide range of [U]/[Pi] ratios (from 0.05 to 1150) at physiologically relevant conditions of pH. Results showed that fluorescence from the four metalloproteins was quenched by UO22+. Stoichiometry reactions, fluorescence quenching mechanisms and complexing properties of metalloproteins, i.e. binding constants and binding sites densities, were determined using classic fluorescence quenching methods and curve-fitting software (PROSECE). It was demonstrated that in our test conditions, the metalloprotein complexation by uranium could be simulated by two specific sites (L1 and L2). Results showed that the U(VI)-Apo-HTf complexation constant values (log K1=7.7, log K2=4.6) were slightly higher than those observed for U(VI)-HSA complex (log K1=6.1, log K2=4.8), U(VI)-MT complex (log K1=6.5, log K2=5.6) and U(VI)-Apo-EqsF complex (log K1=5.3, log K2=3.9). PROSECE fitting studies also showed that the complexing capacities of each protein were different: 550 moles of U(VI) are complexed by Apo-EqSF while only 28, 10 and 5 moles of U(VI) are complexed by Apo-HTf, HSA and MT, respectively. [ABSTRACT FROM AUTHOR]

Abstract: Uranium presents numerous industrial and military uses and one of the most important risks of contamination is dust inhalation. In contrast to the other modes of contamination, the inhaled uranium has been proposed to enter the brain not only by the common route of all modes of exposure, the blood pathway, but also by a specific inhalation exposure route, the olfactory pathway. To test whether the inhaled uranium enter the brain directly from the nasal cavity, male Sprague–Dawley rats were exposed to both inhaled and intraperitoneally injected uranium using the 236U and 233U, respectively, as tracers. The results showed a specific frontal brain accumulation of the inhaled uranium which is not observed with the injected uranium. Furthermore, the inhaled uranium is higher than the injected uranium in the olfactory bulbs (OB) and tubercles, in the frontal cortex and in the hypothalamus. In contrast, the other cerebral areas (cortex, hippocampus, cerebellum and brain residue) did not show any preferential accumulation of inhaled or injected uranium. These results mean that inhaled uranium enters the brain via a direct transfer from the nasal turbinates to the OB in addition to the systemic pathway. The uranium transfer from the nasal turbinates to the OB is lower in animals showing a reduced level of olfactory receptor neurons (ORN) induced by an olfactory epithelium lesion prior to the uranium inhalation exposure. These results give prominence to a role of the ORN in the direct transfer of the uranium from the nasal cavity to the brain. [Copyright &y& Elsevier]

Abstract: Gametes and embryo tissues are known to represent a sensitive target to environmental toxicants exposure. Oocyte quality can impact subsequent developmental competence, pregnancy course and even adult health. The major health concern from depleted uranium (DU) is mainly centred on its chemotoxic properties as a heavy metal. Little attention was paid to the impact of uranium on female gamete quality. The aim of this research was to evaluate the effect of DU on mouse oocyte quality after 49 days of subchronic contamination in drinking water and to correlate the observed effects with the amount of DU accumulated in organs. Four different DU concentrations were investigated: 0 (control), 10 (DU10), 20 (DU20) and 40mgL−1 (DU40). DU did not influence the intensity of ovulation but affected oocyte quality. The proportion of healthy oocytes was reduced by half (P <0.001) from 20mgL−1 compared with control group (0.537; 0.497; 0.282 and 0.239 in control, DU10, DU20 and DU40 groups respectively) whereas no accumulation of DU was recorded in the ovaries whatever the dose tested. Abnormal perivitelline space (P <0.001) or absence of the 1st polar body (P <0.001) was identified as the main characteristic of DU impact. In the context of this study, the NOAEL for oocyte quality was determined at 10mgL−1 in drinking water (1.9mgkg−1 day−1). An increase in the dose of contamination over 20mgL−1 did not amplify the proportion of oocytes contracting a specific alteration but conducted to a diversification in oocytes abnormalities. Further investigations are necessary to correlate morphologic assessment of female gamete with its developmental competence. [Copyright &y& Elsevier]

A method involving high performance liquid chromatography (HPLC) separation associated with tandem mass spectrometry (MS/MS) detection in the multiple reaction monitoring mode was set-up for the measurement of 2-hydroxy-2′-deoxyadenosine (2-OHdAdo). This modified nucleoside, arising from the radical oxidation of 2′-deoxyadenosine (dAdo), has been described in the literature as a potential biological marker of the Fenton reaction. Using the specific and sensitive HPLC-MS/MS assay, 8-oxo-7,8-dihydro-2′-deoxyadenosine, 4,6-diamino-5-formamidopyrimidine and 2-hydroxy-2′-deoxyadenosine (2-OHdAdo) were measured within 2′-deoxyadenosine and DNA solutions either exposed to γ-rays or treated under Fenton reaction conditions. It was found that the yield of 2-OHdAdo was low compared to that of 8-oxodAdo under most of the oxidative conditions studied. In particular and in contrast to previous works, the formation of 2-OHdAdo was shown to be a minor process both upon gamma irradiation and under Fenton reaction conditions. However, a significant yield of formation of 2-OHdAdo was observed either upon incubation with high concentrations of Fe 2+ ions in the absence of hydrogen peroxide or upon γ-radiolysis of a nucleoside solution in the presence of the copper/ ( o )-phenanthroline complex. [ABSTRACT FROM AUTHOR]

Purpose: Task Group 121 – Effects of ionizing radiation exposure in offspring and next generations – is a task group under the Committee 1 of the International Commission on Radiological Protection (ICRP), approved by the Main Commission on 18th November 2021. The main goals of Task Group 121 are to (1) review and update the scientific literature of relevance to radiation-related effects in the offspring of parent(s) exposed to ionizing radiation in both human and non-human biota; (2) to assess preconceptional and intrauterine effects of radiation exposure and related morbidity and mortality; and, (3) to provide advice about the level of evidence and how to consider these preconceptional and postconceptional effects in the system of radiological protection for humans and non-human biota. Methods: The Task Group is reviewing relevant literature since Publication 90 'Biological effects after prenatal irradiation (embryo and fetus)' (2003) and will include radiation-related effects on future generations in humans, animals, and plants. This review will be conducted to account for the health effects on offspring and subsequent generations in the current system of radiological protection. Radiation detriment calculation will also be reviewed. Finally, preliminary recommendations will be made to update the integration of health effects in offspring and next generations in the system of radiological protection. Results: A Workshop, jointly organized by ICRP Task Group 121 and European Radiation Protection Research Platforms MELODI and ALLIANCE was held in Budapest, Hungary, from 31st May to 2nd June 2022. Participants discussed four important topics: (1) hereditary and epigenetic effects due to exposure of the germ cell line (preconceptional exposure), (2) effects arising from exposure of the embryo and fetus (intrauterine exposure), (3) transgenerational effects on biota, and (4) its potential impact on the system of radiological protection. Conclusions: Based on the discussions and presentations during the breakout sessions, newer publications, and gaps on the current scientific literature were identified. For instance, there are some ongoing systematic reviews and radiation epidemiology reviews of intrauterine effects. There are newer methods of Monte Carlo simulation for fetal dosimetry, and advances in radiation genetics, epigenetics, and radiobiology studies. While the current impact of hereditary effects on the global detriment was reported as small, the questions surrounding the effects of radiation exposure on offspring and the next generation are crucial, recurring, and with a major focus on exposed populations. This article summarizes the workshop discussions, presentations, and conclusions of each topic and introduces the special issue of the International Journal of Radiation Biology resulting from the discussions of the meeting. [ABSTRACT FROM AUTHOR]

Concentration of uranium (U), a naturally encountered radioactive element in earth's crust, can be enhanced in freshwater ecosystems (μg.L−1 – mg.L−1) due to various anthropogenic activities. The consequent aquatic organism exposure to U leads to its accumulation in all organs, particularly in the gonad, and in subcellular fractions (mainly the cytosol); then it is known to affect fish at several biological levels, and more particularly, at a reproduction endpoint, with a decrease in the total number of eggs, spawn events and larvae survival. The understanding of U reprotoxicity requires the fine knowledge of its speciation at molecular level, i.e., its interaction with cytosolic biomolecules. In this study, we focus on the U-protein interactions in gonads. A non-denaturating extraction protocol combined with size exclusion chromatography (SEC) allowed the separation of metal-protein complexes in ovaries of U-contaminated wild roaches before their elemental detection (ICP MS). This enables unprecedented information to be obtained about U distribution in ovaries of autochthonous fish, Rutilus rutilus , which is different in some points from that obtained in the model species, Danio rerio under controlled laboratory conditions at a similar concentration level. Finally, the ability to transpose results from model to autochthonous fish was briefly discussed. • Comparison of U-protein distribution and U–P coelutions between wild roach and zebrafish model. • The distribution of uranium between all identified U fractions in roach is more homogeneous. • Linear relationship between phosphorus and uranium percentages in the main U fraction. • Vitellogenin and its fragments, including maturation products, are expected to bind U. • Reproduction cycle and protein content in ovaries may play a key role in the uranium distribution. [ABSTRACT FROM AUTHOR]

Multigenerational studies have become of great interest in ecotoxicology since the consequence of parental exposure to contaminants on offspring generations was established in situ or in laboratory conditions. The present study mainly examined the chronic effects of external Cs‐137 gamma irradiation exposure at 4 dose rates (control, 0.5, 5, and 50 mGy h–1) on adult zebrafish (F0) exposed for 10 d and their progeny (F1) exposed or unexposed for 4 to 5 d. The main endpoints investigated included parental reproductive performance, embryo‐larval survival, DNA alterations, and reactive oxygen species (ROS) production in F0 and F1. No effects on reproductive success, fecundity, or egg fertilization rate were observed. However, drastic effects were observed on F1 exposed to 50 mGy h–1, resulting in a mortality rate of 100%. The drastic effects were also observed when the progeny was not irradiated. It was demonstrated that the sensitivity of the embryos was mainly attributable to parental irradiation. Moreover, these drastic effects induced by adult irradiation disappeared over time when 10 d–irradiated adults were placed in a nonirradiated condition. Alterations in larval DNA were observed for the 3 dose rates, and an increase of ROS production was also shown for the 2 lowest dose rates. The present study improves our understanding of the consequences of parental exposure conditions to the progeny. Furthermore, it provides an incentive to take transmitted generational effects into account in ecological risk assessments. Environ Toxicol Chem 2019;38:2556–2567. © 2019 SETAC [ABSTRACT FROM AUTHOR]

• 10 days parental exposure to 50 mGy. h −1 led to F1 early malformations and mortality. • Offspring mortality was assigned to parental exposure, i.e. transmitted effect. • Irradiation-induced oxidative stress and DNA damage did not impact reproduction. • Female exposure disrupted oocyte development leading to altered phenotype in offspring. Recent laboratory studies focusing on multigenerational approach demonstrated drastic phenotypic effects after chronic fish irradiation exposure. No irradiation effect at phenotypic scale was observed for F0 (reproductive performances) while early mortality and malformations were observed in F1 offspring whether they were irradiated or not. The objective was to study molecular mechanisms likely to be involved in these phenotypic effects induced by parental irradiation. Thus, F0 adult zebrafish were irradiated for ten days until reproduction and maternal involvement in offspring development was assessed. Levels of maternal provided cortisol and vitellogenin, needed for embryo development, were not impacted by irradiation. However, maternal transcriptome highlighted irradiation effect on processes involved in oocyte development, as well as on essential maternal factors needed for offspring development. Therefore, this study highlighted the importance of parental exposure on offspring fate and of the importance of multigenerational exposure in risk assessment. [Display omitted] [ABSTRACT FROM AUTHOR]

Wildlife is subject to various sources of pollution, including ionizing radiation. Adverse effects can impact the survival, growth, or reproduction of organisms, later affecting population dynamics. In invertebrates, reproduction, which directly impacts population dynamics, has been found to be the most radiosensitive endpoint. Understanding the underlying molecular pathways inducing this reproduction decrease can help to comprehend species-specific differences in radiosensitivity. From our previous studies, we found that decrease in reproduction is life stage dependent in the roundworm Caenorhabditis elegans, possibly resulting from an accumulation of damages during germ cell development and gamete differentiation. To go further, we used the same experimental design to assess more precisely the molecular determinants of reproductive toxicity, primarily decreases in gamete number. As before, worms were chronically exposed to 50 mGy·h−1 external gamma ionizing radiation throughout different developmental periods (namely embryogenesis, gametogenesis, and full development). To enable cross species extrapolation, conserved molecular pathways across invertebrates and vertebrates were analysed: apoptosis and MAP kinase Ras/ERK (MPK-1), both involved in reproduction and stress responses. Our results showed that these pathways are life-stage dependent, resulting from an accumulation of damages upon chronic exposure to IR throughout the life development. The Ras/ERK pathway was activated in our conditions in the pachytene region of the gonad where it regulates cell fate including apoptosis, but not in the ovulation zone, where it controls oocyte maturation and ovulation. Additionally, assessment of germ cell proliferation via Ras/ERK pathway showed no effect. Finally, a functional analysis of apoptosis revealed that while the decrease of the ovulation rate is caused by DNA-damaged induced apoptosis, this process does not occur in spermatocytes. Thus, sperm decrease seems to be mediated via another mechanism, probably a decrease in germ cell proliferation speed that needs further investigation to better characterize sex-specific responses to IR exposure. These results are of main importance to describe radio-induced reprotoxic effects and contribute as weight of evidence for the AOP #396 "Deposition of ionizing energy leads to population decline via impaired meiosis". [ABSTRACT FROM AUTHOR]

Background: Individual functional modifications shape the ability of wildlife populations to cope with anthropogenic environmental changes. But instead of adaptive response, human-altered environments can generate a succession of deleterious functional changes leading to the extinction of the population. To study how persistent anthropogenic changes impacted local species' population status, we characterised population structure, genetic diversity and individual response of gene expression in the tree frog Hyla orientalis along a gradient of radioactive contamination around the Chernobyl nuclear power plant. Results: We detected lower effective population size in populations most exposed to ionizing radiation in the Chernobyl Exclusion Zone that is not compensated by migrations from surrounding areas. We also highlighted a decreased body condition of frogs living in the most contaminated area, a distinctive transcriptomics signature and stop-gained mutations in genes involved in energy metabolism. While the association with dose will remain correlational until further experiments, a body of evidence suggests the direct or indirect involvement of radiation exposure in these changes. Conclusions: Despite ongoing migration and lower total dose rates absorbed than at the time of the accident, our results demonstrate that Hyla orientalis specimens living in the Chernobyl Exclusion Zone are still undergoing deleterious changes, emphasizing the long-term impacts of the nuclear disaster. [ABSTRACT FROM AUTHOR]

Reproductive effects of ionizing radiation in organisms have been observed under laboratory and field conditions. Such assessments often rely on associations between exposure and effects, and thus lacking a detailed mechanistic understanding of causality between effects occurring at different levels of biological organization. The Adverse Outcome Pathway (AOP), a conceptual knowledge framework to capture, organize, evaluate and visualize the scientific knowledge of relevant toxicological effects, has the potential to evaluate the causal relationships between molecular, cellular, individual, and population effects. This paper presents the first development of a set of consensus AOPs for reproductive effects of ionizing radiation in wildlife. This work was performed by a group of experts formed during a workshop organized jointly by the Multidisciplinary European Low Dose Initiative (MELODI) and the European Radioecology Alliance (ALLIANCE) associations to present the AOP approach and tools. The work presents a series of taxon-specific case studies that were used to identify relevant empirical evidence, identify common AOP components and propose a set of consensus AOPs that could be organized into an AOP network with broader taxonomic applicability. Expert consultation led to the identification of key biological events and description of causal linkages between ionizing radiation, reproductive impairment and reduction in population fitness. The study characterized the knowledge domain of taxon-specific AOPs, identified knowledge gaps pertinent to reproductive-relevant AOP development and reflected on how AOPs could assist applications in radiation (radioecological) research, environmental health assessment, and radiological protection. Future advancement and consolidation of the AOPs is planned to include structured weight of evidence considerations, formalized review and critical assessment of the empirical evidence prior to formal submission and review by the OECD sponsored AOP development program. [ABSTRACT FROM AUTHOR]

Abstract: This study aimed to determine how the citric acid assisted phytoextraction of uranium (U) by sunflowers impacted on the remobilisation of U in soil, its subsequent transfer to plants and its further distribution intra-planta. Consequences of the flux of nutrient elements [iron (Fe) and zinc (Zn)] able to interfere with U during this process were also specifically addressed. A U-contaminated soil receiving different citric acid treatments in terms of dose delivered and frequency of delivery was studied. Dynamics of remobilisation in soil were assessed using DGT (Diffusive Gradient in Thin-film) measurements, and phytoextraction experiments were conducted in a Rhizoplan device. All treatments induced a remobilisation of U and Fe from the soil solid-phase to the soil solution. Consequently, sunflower uptake of U was greatly enhanced, whereas the uptake of Fe was not affected – in accordance with the high regulation of this nutrient in the plant. As for U, the Zn uptake increased due to the citric acid treatment. The DGT-measured concentration correlated well with the concentration taken up by plants for U. Nevertheless, under all conditions, U fluxes to DGT were higher than U fluxes to plants, suggesting that DGT did not mimic the plant uptake mechanism for U. There was no correlation found for Fe, due to its plant uptake regulation. Distribution of these elements in planta was strongly impacted by citric acid, with an increase in translocation from root-to-shoot of both U and Fe, whereas Zn remained mainly in the roots. Such an increase was expected for U but was very surprising for Fe, suggesting that the presence of U in plants may have interfered with mechanisms that regulate Fe homeostasis. [Copyright &y& Elsevier]

In nuclear fuel cycle facilities, workers may inhale airborne uranium compounds that lead to internal contamination, with various exposure scenarios depending on the workplace. These exposures can be chronic, repeated, or acute, and can involve many different compounds. The effect of uranium after multiple scenarios of exposure is unknown. The aim of this study, therefore, was to investigate the genotoxic and biokinetics consequences of exposure to depleted insoluble uranium dioxide (UO 2 ) by repeated or acute inhalation on subsequent acute inhalation of moderately soluble uranium peroxide (UO 4 ) in rats. The results show that UO 2 repeated preexposure by inhalation increases the genotoxic effects of UO 4 inhalation, assessed by comet assay, in different cell types, when UO 4 exposure alone has no effect. At the same time, the study of UO 4 bioaccumulation showed that the UO 4 biokinetics in the kidneys, gastrointestinal tract, and excreta, but not in the lungs, were slightly modified by previous UO 2 exposures. All these results show that both genotoxic and biokinetics effects of uranium may depend on preexposure and that repeated exposure induces a potentiation effect compared with acute exposure. [ABSTRACT FROM AUTHOR]

Oxidation reactions that involve several oxygen and nitrogen reactive species together with nucleobase radical cations give rise among various classes of lesions to modified bases. About 70 of oxidized nucleosides that include diastereomeric forms have been characterized in mechanistic studies involving isolated DNA and related model compounds. However, only eight modified bases have been accurately measured within cellular DNA upon exposure to either γ or UVA radiations. Emphasis is placed in this survey on recent developments of HPLC associated with tandem mass spectrometry (MS/MS) operating in the mild electrospray ionization mode. Interestingly, the HPLC-MS/MS assay in the multiple reaction monitoring mode appears to be the more sensitive and accurate method currently available for singling out several oxidized nucleosides including 8-oxo-7,8-dihydro-2′-deoxyguanosine, 8-oxo-7,8-dihydro-2′-deoxyadenosine, 5-formyl-2′-deoxyuridine, 5-(hydroxymethyl-2′-deoxyuridine, 5-hydroxy-2′-deoxyuridine, and the four diastereomers of 5,6-dihydroxy-5,6-dihydrothymidine within isolated and cellular DNA. However, one limitation of the assay that also applied to all chromatographic methods is the slight side-oxidation of normal bases during DNA extraction and subsequent work-up. This explains why the combined use of DNA repair glycosylases with either the comet assay or the alkaline elution technique is a better alternative to monitor the formation of low levels of oxidized bases within cellular DNA. [Copyright &y& Elsevier]

Contamination of the environment after the Chernobyl and Fukushima Daiichi nuclear power plant (NPP) disasters led to the exposure of a large number of humans and wild animals to radioactive substances. However, the sub-lethal consequences induced by these absorbed radiological doses remain understudied and the long-term biological impacts largely unknown. We assessed the biological effects of chronic exposure to ionizing radiation (IR) on embryonic development by exposing zebrafish embryo from fertilization and up to 120 hours post-fertilization (hpf) at dose rates of 0.5 mGy/h, 5 mGy/h and 50 mGy/h, thereby encompassing the field of low dose rates defined at 6 mGy/h. Chronic exposure to IR altered larval behaviour in a light-dark locomotor test and affected cardiac activity at a dose rate as low as 0.5 mGy/h. The multi-omics analysis of transcriptome, proteome and transcription factor binding sites in the promoters of the deregulated genes, collectively points towards perturbations of neurogenesis, muscle development, and retinoic acid (RA) signaling after chronic exposure to IR. Whole-mount RNA in situ hybridization confirmed the impaired expression of the transcription factors her4.4 in the central nervous system and myogenin in the developing muscles of exposed embryos. At the organ level, the assessment of muscle histology by transmission electron microscopy (TEM) demonstrated myofibers disruption and altered neuromuscular junctions in exposed larvae at 5 mGy/h and 50 mGy/h. The integration of these multi-level data demonstrates that chronic exposure to low dose rates of IR has an impact on neuronal and muscle progenitor cells, that could lead to motility defects in free swimming larvae at 120 hpf. The mechanistic understanding of these effects allows us to propose a model where deregulation of RA signaling by chronic exposure to IR has pleiotropic effects on neurogenesis and muscle development. [ABSTRACT FROM AUTHOR]

Emission of ionizing radiation (IR) in the environment is a natural phenomenon which can be enhanced by human activities. Ecosystems are then chronically exposed to IR. But environmental risk assessment of chronic exposure suffers from a lack of knowledge. Extrapolation of data from acute to chronic exposure is not always relevant, and can lead to uncertainties as effects could be different between the two irradiation modes, especially regarding reproduction endpoint, which is an ecologically relevant parameter. In the present study, we decided to refine the understanding of the molecular mechanisms involved in response to acute and chronic γ-irradiation by a global proteome label free LC-MS/MS analysis. C. elegans were exposed to 3 common cumulated radiation doses for acute or chronic exposure condition and global modification of the proteome was studied. This analysis of protein expression has demonstrated the modulation of proteins involved in regulatory biological processes such as lipid transport, DNA replication, germ cell development, apoptosis, ion transport, cuticle development, and aging at lower doses than those for which individual effects on reproduction have been previously observed. Thus, these proteins could constitute early and sensitive markers of radio-induced reprotoxicity; more specifically HAT-1, RPS-19 in acute and VIT-3 for chronic conditions that are expressed in a dose-dependent manner. Finally, to focus on reproduction process, this analysis showed either repression or overexpression of 12 common proteins in organisms exposed to acute or chronic irradiation, respectively. These proteins include the vitellogenin cluster notably involved in lipid transport and oocyte maturation and proteins involved in cuticle development and molting i.e. COL-14, GLF-1, NOAH-1, NOAH-2, ACN-1. These results show that protein expression modulation is a sensitive and predictive marker of radio-induced reproductive effects, but also highlight limitation of data extrapolation from acute to chronic exposure for environmental risk assessment. Unlabelled Image • Opposite modulation of some key proteins after acute vs. chronic exposure to γ-rays. • Chronic BP GO terms include lipid transport, DNA replication, germ cell development. • Acute BP GO terms include hatching success, embryo development, apoptotic processes. • Some reproduction process proteins are mis-regulated from 0.5 Gy chronic exposure. • Proteome modification is a sensitive marker of the gamma radiation effects. [ABSTRACT FROM AUTHOR]

Living species are chronically exposed to environmental ionizing radiations from sources that can be overexpressed by nuclear accidents. In invertebrates, reproduction is the most radiosensitive studied endpoint, likely to be connected with aging. Surprisingly, aging is a sparsely investigated endpoint after chronic ionizing radiation, whereas understanding it is of fundamental interest in biology and medicine. Indeed, aging and aging-related diseases (e.g., cancer and degenerative diseases) cause about 90% of deaths in developed countries. Therefore, glp-1 sterile Caenorhabditis elegans nematode was used to assess the impact of chronic gamma irradiation on the lifespan. Analyses were performed, at the individual level, on aging and, in order to delve deeper into the mechanisms, at the molecular level, on oxidative damage (carbonylation), biomolecules (lipids, proteins and nucleic acids) and their colocalization. We observed that ionizing radiation accelerates aging (whatever the duration (3–19 days)/dose (0.5–24 Gy)/dose rate (7 and 52 mGy h−1) tested) leading to a longevity value equivalent to that of wt nematode (∼25–30 days). Moreover, the level of protein oxidative damage (carbonylation) turned out to be good cellular biomarker of aging, since it increases with age. Conversely, chronic radiation treatments reduced carbonylation levels and induced neutral lipid catabolism whatever the dose rate and the final delivered dose. Finally, under some conditions a lipid-protein colocalization without any carbonyl was observed; this could be linked to yolk accumulation in glp-1 nematodes. To conclude, we noticed through this study a link between chronic gamma exposure, lifespan shortening and lipid level decrease associated with a decrease in the overall carbonylation. Image 1 • Chronic γ-radiation shortens glp-1 C. elegans lifespan without linear dose-response. • Carbonylation turned out to be a good biomarker of aging. • γ-radiation yields lipid and carbonylation catabolism whatever dose and dose rate. • Radiation-induced lipid catabolism is associated with reduced C. elegans longevity. • Lipid-protein colocalization with no carbonyls could be linked to accumulated yolk. [ABSTRACT FROM AUTHOR]

Uranium (U) toxicity patterns for fish have been mainly determined under laboratory‐controlled waterborne exposure conditions. Because fish can take up metals from water and diet under in situ exposure conditions, a waterborne U exposure experiment (20 μg L−1, 20 d) was conducted in the laboratory to investigate transfer efficiency and target organ distribution in zebrafish Danio rerio compared with combined waterborne exposure (20 μg L−1) and diet‐borne exposure (10.7 μg g−1). 233Uranium was used as a specific U isotope tracer for diet‐borne exposure. Bioaccumulation was examined in the gills, liver, kidneys, intestine, and gonads of D. rerio. Concentrations in the organs after waterborne exposure were approximately 500 ng g−1 fresh weight, except in the intestine (> 10 μg g−1 fresh wt) and the kidneys (200 ng g−1 fresh wt). No significant difference was observed between waterborne and diet‐borne conditions. Trophic U transfer in organs was found but at a low level (< 10 ng g−1 fresh wt). Surprisingly, the intestine appeared to be the main target organ after both tested exposure modalities. The gonads (57% at 20 d) and the liver (41% at 20 d) showed the highest accumulated relative U burdens. Environ Toxicol Chem 2019;38:90–98. © 2018 SETAC [ABSTRACT FROM AUTHOR]

Together with nematodes and rotifers, tardigrade belong to micrometazoans that can cope with environmental extremes such as UV and solar radiations, dehydration, supercooling or overheating. Tardigrade can resist the harshest conditions by turning to cryptobiosis, an anhydrobiotic state that results from almost complete dehydration and is characterized by an ametabolic status. Although reports have challenged the molecular basis of the mechanisms underlying genomic injury resistance, little is yet known regarding the possible involvement of other tardigrade macromolecules in injury during a stress experience. In this report, we show that the tardigrade Hypsibius exemplaris can accumulate molecular damages by means of in situ detection of carbonyls. Furthermore, we demonstrate that living tardigrade can accumulate carbonylation. Finally, we reveal that anhydrobiotic tardigrade can be constitutively affected by carbonylation that marks aging in other metazoans. [ABSTRACT FROM AUTHOR]

Early studies have shown that cesium (Cs + ) competes with the macronutrient potassium (K + ) for uptake by plants. The present study investigates the effect of K + supply on Cs + uptake and translocation in Arabidopsis thaliana . Taking advantage of the frequent use of this model plant in previous molecular studies, we discuss the link between functional features described for transporters involved in K + (and sometimes in Cs + ) uptake and results obtained here in both Cs + influx and accumulation experiments under different K + -treatments. In low K + condition (10 μM), we observed that roots affinity for Cs + increased significantly and Cs + concentration in the external medium clearly affected the efficiency of Cs + uptake. Our results are consistent with previous molecular studies indicating the role of the high-affinity K + carrier AtHAK5 in Cs + uptake under K + -deprivation. Further experiments show that the lack of AtHAK5 has no more effect on Cs + uptake for external Cs + concentration above 100 μM. We propose that non-selective cation channels, likely involved in Cs + uptake under K + -sufficient conditions according to previous studies, could also mediate Cs + uptake under K + -starvation and high Cs + concentrations. Finally, evidences for Cs + translocation mediated by K + channels are discussed. [ABSTRACT FROM AUTHOR]

All key biological macromolecules are susceptible to carbonylation – an irreparable oxidative damage with deleterious biological consequences. Carbonyls in proteins, lipids and DNA from cell extracts have been used as a biomarker of oxidative stress and aging, but formation of insoluble aggregates by carbonylated proteins precludes quantification. Since carbonylated proteins correlate with and become a suspected cause of morbidity and mortality in some organisms, there is a need for their accurate quantification and localization. Using appropriate fluorescent probes, we have developed an in situ detection of total proteins, DNA, RNA, lipids and carbonyl groups at the level of the whole organism. In C. elegans , we found that after UV irradiation carbonylation co-localizes mainly with proteins and, to a lesser degree, with DNA, RNA and lipids. The method efficiency was illustrated by carbonylation induction assessment over 5 different UV doses. The procedure enables the monitoring of carbonylation in the nematode C. elegans during stress, aging and disease along its life cycle including the egg stage. [ABSTRACT FROM AUTHOR]

New data on the nature of the protein targets of uranium (U) within zebrafish gills were collected after waterborne exposure, with the aim of a better understanding of U toxicity mechanisms. Some common characteristics of the U protein target binding properties were found, such as their role in the regulation of other essential metals and their phosphorus content. In total, 21 potential protein targets, including hemoglobin, are identified and discussed in terms of the literature. Environ Toxicol Chem 2016;35:736-741. © 2015 SETAC [ABSTRACT FROM AUTHOR]

The interactions between uranium and two functional proteins (AChE and Vtg) were investigated using fluorescence quenching measurements. The combined use of a microplate spectrofluorometer and logarithmic additions of uranium into protein solutions allowed us to define the fluorescence quenching over a wide range of [U]/[Pi] ratios (from 1 to 3235) at physiologically relevant conditions of pH. Results showed that fluorescence from the two functional proteins was quenched by UO. Stoichiometry reactions, fluorescence quenching mechanisms and complexing properties of proteins, i.e. binding constants and binding sites densities, were determined using classic fluorescence quenching methods and curve-fitting software (PROSECE). It was demonstrated that in our test conditions, the protein complexation by uranium could be simulated by two specific sites (L and L). The obtained complexation constant values are log K = 5.7 (±1.0), log K = 4.9 (±1.1); L = 83 (±2) L = 2220 (±150) for U(VI) - Vtg and log K = 8.1 (±0.9), log K = 6.6 (±0.5), L = 115 (±16), L = 530 (±23) for U(VI)-AChE (L is expressed in mol/mol of protein). [ABSTRACT FROM AUTHOR]

The toxicity of uranium (U) to aquatic organisms depends notably on its compartmentalization in organs, tissues, cells as well as on its distribution among biomolecules. In order to contribute to the understanding of U accumulation and associated toxicity mechanisms in case of waterborne exposure, this study focused on U fate in the gills epithelia, uptake pathway, of the fish model Danio rerio (zebrafish). U distribution among cytosolic biomolecules was investigated after no addition (0 μg L-1 (c0) for 3 and 30 d), chronic (20 μg L-1 (c20) for 30 d) and acute (20 μg L-1 (c20) and 250 μg L-1 (c250) for 3 d) exposures to depleted U. Cytosolic U accounted for an average of 24-32% of gills burden for c20 and c250, respectively. Size Exclusion Chromatography (SEC) coupled with Inductively Coupled Plasma-Sector Field Mass Spectrometry (ICP-SFMS) allowed identification of ecotoxicologically relevant U-containing fractions among cytosolic biomolecules as a function of exposure conditions. In c0 and c20 samples, most U (ca. 80%) was found in the Low Molecular Weight fraction (LMW, <18 kDa), often considered as a detoxifying fraction. In c250 exposed fish, U was equally distributed between LMW (40%) and High Molecular Weight (HMW, 150-670 kDa; 40%) fractions, the latter including sensitive metalloproteins. Uranium-biomolecules were co-eluted with endogenous essential metal (Fe, Cu and Zn) species, however, no major influence on their cytosolic concentration and distribution pattern among cytosolic proteins was found. [ABSTRACT FROM AUTHOR]

Although reproduction in fish is known to be sensitive to metal exposure, few ecotoxicological studies have focused on the toxicological effects of metals. Because uranium (U) is naturally present in aquatic ecosystems (0.6-2 mg/L), freshwater organisms are subjected to chronic U exposure. Although new standardized assays are currently being developed to mimic realistic exposure conditions, they could be improved by taking into account the contamination that occurs throughout the life cycle of fish. The authors initially evaluated the effect of food (commercial flakes vs pure Spirulina) and ionic composition of the exposure medium on the reproductive performance of Danio rerio. The effects of U exposure on reproduction then were assessed 1) for the F0 adult stage at short exposure times (5 d, 20 d, and 40 d), and 2) for the F0 stage and the F1 generation after 200 d of exposure to control, low (20 µg U/L), and moderate (250 µg U/L) waterborne levels of U. Reproductive endpoints (reproductive success, fecundity, number of spawns, egg and larvae viability, and hatching) were measured mainly after the first spawn and after 10 d of cumulative spawns. The authors evaluated the plasticity of these endpoints and compared the effect of exposure conditions to identify the most relevant markers of the effect of U exposure on reproductive performance of D. rerio. Environ Toxicol Chem 2014;33:1817-1824. © 2014 SETAC [ABSTRACT FROM AUTHOR]

Pollutants that occur at sublethal concentrations in the environment may lead to chronic exposure in aquatic organisms. If these pollutants bioaccumulate, then organisms higher in the food chain may also be at risk. Increased attention has thus been focused on the relative importance of dietary uptake, but additional knowledge of the cellular distribution of metals after dietary exposure is required to assess the potential toxicity. The authors address concerns relating to increasing uranium (U) concentrations (from 12 µg/L to 2 mg/L) in the freshwater ecosystem caused by anthropogenic activities. The objective of the present study is to compare uranium bioaccumulation levels in tissues and in the subcellular environment. The authors focused on the cytosol fraction and its microlocalization (TEM-EDX) in the gills and the hepatopancreas (HP) of the crayfish Orconectes limosus after 10 d of direct exposure (at concentrations of 20, 100, and 500 µg/L) and five trophic exposure treatments (at concentrations from 1 to 20 µg/g). Results indicated that adsorption of uranium on the cuticle represents the main contribution of total uranium accumulation to the animal. Accumulation in the gills should be considered only as a marker of waterborne uranium exposure. Accumulation in the HP after trophic environmental exposure conditions was higher (18.9 ± 3.8 µg/g) than after direct exposure. Moreover, no significant difference in the subcellular distribution of uranium (50%) in HP was observed between animals that had been exposed to both types of treatment. A potential toxic effect after uranium accumulation could therefore exist after trophic exposure. This confirms the need to focus further studies on the metal (uranium) risk assessment. Environ. Toxicol. Chem. 2013;32:410-416. © 2012 SETAC [ABSTRACT FROM AUTHOR]

Abstract: Anthropogenic release of uranium (U), originating from the nuclear fuel cycle or military activities, may considerably increase U concentrations in terrestrial and aquatic ecosystems above the naturally occurring background levels found throughout the environment. With a projected increase in the world-wide use of nuclear power, it is important to improve our understanding of the possible effects of this metal on the aquatic fauna at concentrations commensurate with the provisional drinking water guideline value of the World Health Organization (15μgU/L). The present study has examined the mitochondrial function in brain and skeletal muscles of the zebrafish, Danio rerio, exposed to 30 and 100μg/L of waterborne U for 10 and 28 days. At the lower concentration, the basal mitochondrial respiration rate was increased in brain at day 10 and in muscles at day 28. This is due to an increase of the inner mitochondrial membrane permeability, resulting in a decrease of the respiratory control ratio. In addition, levels of cytochrome c oxidase subunit IV (COX-IV) increased in brain at day 10, and those of COX-I increased in muscles at day 28. Histological analyses performed by transmission electron microscopy revealed an alteration of myofibrils and a dilatation of endomysium in muscle cells. These effects were largest at the lowest concentration, following 28 days of exposure. [Copyright &y& Elsevier]

Wildlife is chronically exposed to various sources of ionizing radiations, both environmental or anthropic, due to nuclear energy use, which can induce several defects in organisms. In invertebrates, reproduction, which directly impacts population dynamics, has been found to be the most radiosensitive endpoint. Understanding the underlying molecular pathways inducing this reproduction decrease can help in predicting the effects at larger scales (i.e., population). In this study, we used a life stage dependent approach in order to better understand the molecular determinants of reproduction decrease in the roundworm C. elegans. Worms were chronically exposed to 50 mGy·h−1 external gamma ionizing radiations throughout different developmental periods (namely embryogenesis, gametogenesis, and full development). Then, in addition to reproduction parameters, we performed a wide analysis of lipids (different class and fatty acid via FAMES), which are both important signaling molecules for reproduction and molecular targets of oxidative stress. Our results showed that reproductive defects are life stage dependent, that lipids are differently misregulated according to the considered exposure (e.g., upon embryogenesis and full development) and do not fully explain radiation induced reproductive defects. Finally, our results enable us to propose a conceptual model of lipid signaling after radiation stress in which both the soma and the germline participate. [ABSTRACT FROM AUTHOR]