The Paraná River basin is one of the most important in South America and is affected by human activities that take place on its margins. In particular, the De la Cruz stream flows through an industrial pole and the Arrecifes River goes mainly through agricultural fields. The aim of this study was to evaluate the water quality of the De la Cruz stream (S1) and the Arrecifes River (S2) by means of physicochemical parameters, including metals and pesticides concentrations. Since amphibians are good indicators of environmental quality, bioassays with Rhinella arenarum were carried on. For lethal and sublethal parameters, embryos and larvae were exposed to a dilution gradient of water samples and AMPHITOX Solution (AS) as negative control for 504 h. For the determination of oxidative stress biomarkers (Catalase -CAT-, Glutathione S-Transferase -GST-, Reduced Glutathione -GSH-, and lipid peroxidation -TBARS-), embryos and larvae were exposed to undiluted water samples and AS. For the determination of micronuclei, larvae at hind limb bud stage (S.28) were exposed to undiluted water samples, simultaneously with negative and positive controls (AS and cyclophosphamide 40 mg/L, respectively). Dissolved oxygen was low in both sites and the copper levels exceeded the Argentine limit for the protection of aquatic life. In embryos exposure, water sample from S1 caused lethal effects (504h-LC50 = 49 (28–71.6)%), increased TBARS levels, and GST and CAT activities. In larvae exposure, water sample from this site decreased CAT activity, while the water sample from S2 caused important lethal effects (504h-LC50 = 98.72 (60.60–302.52)%), low GSH levels and increased GST activity. Water samples from both sites induced higher micronuclei frequency than the negative control. This study alerts about the degradation of water quality of the studied sites including lethal and sublethal effects in R. arenarum that can jeopardize the native populations of this species. | Fil: Peluso, Julieta. Universidad Nacional de San Martín (UNSAM). Instituto de Investigación e Ingeniería Ambiental; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. | Fil: Aronzon, Carolina Mariel. Universidad Nacional de San Martín (UNSAM). Instituto de Investigación e Ingeniería Ambiental; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET); Argentina. | Fil: Ríos de Molina, María del Carmen. Instituto Nacional de Tecnología Agropecuaria (INTA). Instituto Tecnología de Alimentos; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. | Fil: Rojas, Dante Emanuel. Instituto Nacional de Tecnología Agropecuaria (INTA). Instituto Tecnología de Alimentos; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Química Biológica. Instituto de Química Biológica; Argentina. | Fil: Cristos, Diego Sebastian. Instituto Nacional de Tecnología Agropecuaria (INTA). Instituto Tecnología de Alimentos; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Química Biológica. Instituto de Química Biológica; Argentina. | Fil: Pérez Coll, Cristina Silvia. Universidad Nacional de San Martín (UNSAM). Instituto de Investigación e Ingeniería Ambiental; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET); Argentina.

The Paraná River basin is one of the most important in South America and is affected by human activities that take place on its margins. In particular, the De la Cruz stream flows through an industrial pole and the Arrecifes River goes mainly through agricultural fields. The aim of this study was to evaluate the water quality of the De la Cruz stream (S1) and the Arrecifes River (S2) by means of physicochemical parameters, including metals and pesticides concentrations. Since amphibians are good indicators of environmental quality, bioassays with Rhinella arenarum were carried on. For lethal and sublethal parameters, embryos and larvae were exposed to a dilution gradient of water samples and AMPHITOX Solution (AS) as negative control for 504 h. For the determination of oxidative stress biomarkers (Catalase -CAT-, Glutathione S-Transferase -GST-, Reduced Glutathione -GSH-, and lipid peroxidation -TBARS-), embryos and larvae were exposed to undiluted water samples and AS. For the determination of micronuclei, larvae at hind limb bud stage (S.28) were exposed to undiluted water samples, simultaneously with negative and positive controls (AS and cyclophosphamide 40 mg/L, respectively). Dissolved oxygen was low in both sites and the copper levels exceeded the Argentine limit for the protection of aquatic life. In embryos exposure, water sample from S1 caused lethal effects (504h-LC50 = 49 (28–71.6)%), increased TBARS levels, and GST and CAT activities. In larvae exposure, water sample from this site decreased CAT activity, while the water sample from S2 caused important lethal effects (504h-LC50 = 98.72 (60.60–302.52)%), low GSH levels and increased GST activity. Water samples from both sites induced higher micronuclei frequency than the negative control. This study alerts about the degradation of water quality of the studied sites including lethal and sublethal effects in R. arenarum that can jeopardize the native populations of this species.

peer reviewed | Due to expected changes in climate, it is predicted that disease-carrying mosquitoes will expand their geographical range, resulting in increased use of insect growth regulators (IGRs) to face their proliferation. Among IGRs, pyriproxyfen (PXF) is widely used and has been shown to prevent larvae from developing into adults, rendering them unable to reproduce. However, because of the similarity of crustacean and insect endocrine systems, PXF could also impact aquatic crustaceans. In addition, when spreading in the environment, PXF is found in a mixture with other pollutants such as metallic trace elements, which could alter its effect. Consequently, the present work was devoted to analysing the effects of PXF on the methylfarnesoate (MF) hormonal pathway of the freshwater amphipod Gammarus pulex, as well as its combined binary effects with cadmium (Cd), by measuring MF concentration, as well as the relative transcriptional expression of the farnesoic acid O-methyltransferase (FAMeT) (enzyme limiting the MF production), the methoprene-tolerant receptor (Met), and the broad-complex (BrC) as a transcription factor. Results revealed that single exposures to PXF or Cd have mainly overexpressed FAMeT, Met, and BrC but did not significantly affect MF concentration. Conversely, the mixture exposures seemed to suppress these effects and even achieve antagonistic effects. This work confirmed that PXF single exposure could impact non-target organisms such as amphipods through changes in hormonal pathways of MF. In the same way, it highlighted that Cd could also impair the endocrine system of exposed organisms. However, antagonistic effects have been observed in exposure to mixtures, suggesting different long-term consequences on the growth of amphipods under realistic exposure conditions.

Due to expected changes in climate, it is predicted that disease-carrying mosquitoes will expand their geographical range, resulting in increased use of insect growth regulators (IGRs) to face their proliferation. Among IGRs, pyriproxyfen (PXF) is widely used and has been shown to prevent larvae from developing into adults, rendering them unable to reproduce. However, because of the similarity of crustacean and insect endocrine systems, PXF could also impact aquatic crustaceans. In addition, when spreading in the environment, PXF is found in a mixture with other pollutants such as metallic trace elements, which could alter its effect. Consequently, the present work was devoted to analysing the effects of PXF on the methylfarnesoate (MF) hormonal pathway of the freshwater amphipod Gammarus pulex, as well as its combined binary effects with cadmium (Cd), by measuring MF concentration, as well as the relative transcriptional expression of the farnesoic acid O-methyltransferase (FAMeT) (enzyme limiting the MF production), the methoprene-tolerant receptor (Met), and the broad-complex (BrC) as a transcription factor. Results revealed that single exposures to PXF or Cd have mainly overexpressed FAMeT, Met, and BrC but did not significantly affect MF concentration. Conversely, the mixture exposures seemed to suppress these effects and even achieve antagonistic effects. This work confirmed that PXF single exposure could impact non-target organisms such as amphipods through changes in hormonal pathways of MF. In the same way, it highlighted that Cd could also impair the endocrine system of exposed organisms. However, antagonistic effects have been observed in exposure to mixtures, suggesting different long-term consequences on the growth of amphipods under realistic exposure conditions.

Diarrhetic shellfish poisoning (DSP) toxins and pectenotoxins (PTX) produced by endemic species of the genus Dinophysis, mainly D. acuta and D. acuminata, pose a big threat to public health, artisanal fisheries and the aquaculture industry in Southern Chile. This work reports the first detection of lipophilic toxins, including pectenotoxin-2 (PTX-2) and gymnodimine-A (GYM-A), in hard razor clam (Tagelus dombeii) associated with an unprecedented spring bloom −38.4 × 103 cells L−1 in integrated hose sampler (0–10 m) – of Dinophysis acuminata in coastal waters of central Chile. The socio-economic challenges to small-scale fisheries are discussed. The study points to the pressing need for sound policies to face unexpected HAB event, probably due to biogeographical expansions, with a focus on fisheries management, participation of stakeholders, and development of adaptive capacities.

Diarrhetic shellfish poisoning (DSP) toxins and pectenotoxins (PTX) produced by endemic species of the genus Dinophysis, mainly D. acuta and D. acuminata, pose a big threat to public health, artisanal fisheries and the aquaculture industry in Southern Chile. This work reports the first detection of lipophilic toxins, including pectenotoxin-2 (PTX-2) and gymnodimine-A (GYM-A), in hard razor clam (Tagelus dombeii) associated with an unprecedented spring bloom −38.4 × 10³ cells L⁻¹ in integrated hose sampler (0–10 m) – of Dinophysis acuminata in coastal waters of central Chile. The socio-economic challenges to small-scale fisheries are discussed. The study points to the pressing need for sound policies to face unexpected HAB event, probably due to biogeographical expansions, with a focus on fisheries management, participation of stakeholders, and development of adaptive capacities.

International audience | Macrophytes are known to bioaccumulate metals, but a thorough understanding of tolerance strategies and molecular impact of metals in aquatic plants is still lacking. The present study aimed to compare Hg and Cd effects in a representative macrophyte, Elodea nuttallii using physiological endpoints and metabolite profiles in shoots and cytosol. Exposure 24 h to methyl-Hg (30 ng L), inorganic Hg (70 ng L) and Cd (280 μg L) did not affect photosynthesis, or antioxidant enzymes despite the significant accumulation of metals, confirming a sublethal stress level. In shoots, Cd resulted in a higher level of regulation of metabolites than MeHg, while MeHg resulted in the largest number of regulated metabolites and IHg treatment regulated no metabolites significantly. In cytosol, Cd regulated more metabolites than IHg and only arginine, histidine and mannose were reduced by MeHg exposure. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis of data suggested that exposure to MeHg resulted in biochemical changes including aminoacyl-tRNA biosynthesis, glycine, serine and threonine metabolism, nitrogen metabolism, arginine and proline metabolism, cyanoamino acid metabolism, while the treatment of Cd stress caused significant variations in aminoacyl-tRNA biosynthesis and branched-chain amino acids pathways. Data supports an impact of MeHg on N homeostasis, while Cd resulted in an osmotic stress-like pattern and IHg had a low impact. Marked differences in the responses to MeHg and IHg exposure were evidenced, supporting different molecular toxicity pathways and main impact of MeHg on non-soluble compartment, while main impact of IHg was on soluble compartment. Metabolomics was used for the first time in this species and proved to be very useful to confirm and complement recent knowledge gained by transcriptomics and proteomics, highlighting the high interest of multi-omics approaches to identify early impact of environmental pollution.

Macrophytes are known to bioaccumulate metals, but a thorough understanding of tolerance strategies and molecular impact of metals in aquatic plants is still lacking. The present study aimed to compare Hg and Cd effects in a representative macrophyte, Elodea nuttallii using physiological endpoints and metabolite profiles in shoots and cytosol.Exposure 24 h to methyl-Hg (30 ng L⁻¹), inorganic Hg (70 ng L⁻¹) and Cd (280 μg L⁻¹) did not affect photosynthesis, or antioxidant enzymes despite the significant accumulation of metals, confirming a sublethal stress level. In shoots, Cd resulted in a higher level of regulation of metabolites than MeHg, while MeHg resulted in the largest number of regulated metabolites and IHg treatment regulated no metabolites significantly. In cytosol, Cd regulated more metabolites than IHg and only arginine, histidine and mannose were reduced by MeHg exposure. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis of data suggested that exposure to MeHg resulted in biochemical changes including aminoacyl-tRNA biosynthesis, glycine, serine and threonine metabolism, nitrogen metabolism, arginine and proline metabolism, cyanoamino acid metabolism, while the treatment of Cd stress caused significant variations in aminoacyl-tRNA biosynthesis and branched-chain amino acids pathways. Data supports an impact of MeHg on N homeostasis, while Cd resulted in an osmotic stress-like pattern and IHg had a low impact. Marked differences in the responses to MeHg and IHg exposure were evidenced, supporting different molecular toxicity pathways and main impact of MeHg on non-soluble compartment, while main impact of IHg was on soluble compartment. Metabolomics was used for the first time in this species and proved to be very useful to confirm and complement recent knowledge gained by transcriptomics and proteomics, highlighting the high interest of multi-omics approaches to identify early impact of environmental pollution.

International audience | Understanding how essential and toxic elements are distributed in cereal grains is a key to improving the nutritional quality of cereal-based products. The main objective of this work was to characterize the distribution of Cd and of nutrients (notably Cu, Fe, Mn, P, S and Zn) in the durum wheat grain. Laser ablation inductively coupled mass spectrometry and synchrotron micro X-ray fluorescence were used for micro-scale mapping of Cd and nutrients. A dissection approach was used to quantitatively assess the distribution of Cd and nutrients among grain tissues. Micro X-ray absorption near-edge spectroscopy was used to identify the Cd chemical environment in the crease. Cadmium distribution was characterized by strong accumulation in the crease and by non-negligible dissemination in the endosperm. Inside the crease, Cd accumulated most in the pigment strand where it was mainly associated with sulfur ligands. High-resolution maps highlighted very specific accumulation areas of some nutrients in the germ, for instance Mo in the root cortex primordia and Cu in the scutellum. Cadmium loading into the grain appears to be highly restricted. In the grain, Cd co-localized with several nutrients, notably Mn and Zn, which challenges the idea of selectively removing Cd-enriched fractions by dedicated milling process.

Understanding how essential and toxic elements are distributed in cereal grains is a key to improving the nutritional quality of cereal-based products. The main objective of this work was to characterize the distribution of Cd and of nutrients (notably Cu, Fe, Mn, P, S and Zn) in the durum wheat grain. Laser ablation inductively coupled mass spectrometry and synchrotron micro X-ray fluorescence were used for micro-scale mapping of Cd and nutrients. A dissection approach was used to quantitatively assess the distribution of Cd and nutrients among grain tissues. Micro X-ray absorption near-edge spectroscopy was used to identify the Cd chemical environment in the crease. Cadmium distribution was characterized by strong accumulation in the crease and by non-negligible dissemination in the endosperm. Inside the crease, Cd accumulated most in the pigment strand where it was mainly associated with sulfur ligands. High-resolution maps highlighted very specific accumulation areas of some nutrients in the germ, for instance Mo in the root cortex primordia and Cu in the scutellum. Cadmium loading into the grain appears to be highly restricted. In the grain, Cd co-localized with several nutrients, notably Mn and Zn, which challenges the idea of selectively removing Cd-enriched fractions by dedicated milling process.