International audience | Antibiotics have been increasingly used over the past decades for human medicine, food-animal agriculture, aquaculture, and plant production. A significant part of the active molecules of antibiotics can be released into the environment, in turn affecting ecosystem functioning and biogeochemical processes. At lower organizational scales, these substances affect bacterial symbionts of insects, with negative consequences on growth and development of juveniles, and population dynamics. Yet, the multiple alterations of cellular physiology and metabolic processes have remained insufficiently explored in insects. We evaluated the effects of five antibiotics with different mode of action, i.e. ampicillin, cefradine, chloramphenicol, cycloheximide, and tetracycline, on the survival and ultrastructural organization of the flight muscles of newly emerged blow flies Chrysomya albiceps. Then, we examined the effects of different concentrations of antibiotics on mitochondrial protein content, efficiency of oxidative phosphorylation, and activity of transaminases (Glutamate oxaloacetate transaminase and glutamate pyruvate transaminase) and described the cellular metabolic perturbations of flies treated with antibiotics. All antibiotics affected the survival of the insects and decreased the total mitochondrial protein content in a dose-dependent manner. Ultrastructural organization of flight muscles in treated flies differs dramatically compared to the control groups and severe pathological damages/structures disorganization of mitochondria appeared. The activities of mitochondrial transaminases significantly increased with increased antibiotic concentrations. The oxidation rate of pyruvate + proline from isolated mitochondria of the flight muscles of 1-day-old flies was significantly reduced at high doses of antibiotics. In parallel, the level of several metabolites, including TCA cycle intermediates, was reduced in antibiotics-treated flies. Overall, antibiotics provoked a system-wide alteration of the structure and physiology of flight muscles of the blow fly Ch. albiceps, and may have fitness consequences at the organism level. Environmental antibiotic pollution is likely to have unwanted cascading ecological effects of insect population dynamics and community structure.

International audience | Antibiotics have been increasingly used over the past decades for human medicine, food-animal agriculture, aquaculture, and plant production. A significant part of the active molecules of antibiotics can be released into the environment, in turn affecting ecosystem functioning and biogeochemical processes. At lower organizational scales, these substances affect bacterial symbionts of insects, with negative consequences on growth and development of juveniles, and population dynamics. Yet, the multiple alterations of cellular physiology and metabolic processes have remained insufficiently explored in insects. We evaluated the effects of five antibiotics with different mode of action, i.e. ampicillin, cefradine, chloramphenicol, cycloheximide, and tetracycline, on the survival and ultrastructural organization of the flight muscles of newly emerged blow flies Chrysomya albiceps. Then, we examined the effects of different concentrations of antibiotics on mitochondrial protein content, efficiency of oxidative phosphorylation, and activity of transaminases (Glutamate oxaloacetate transaminase and glutamate pyruvate transaminase) and described the cellular metabolic perturbations of flies treated with antibiotics. All antibiotics affected the survival of the insects and decreased the total mitochondrial protein content in a dose-dependent manner. Ultrastructural organization of flight muscles in treated flies differs dramatically compared to the control groups and severe pathological damages/structures disorganization of mitochondria appeared. The activities of mitochondrial transaminases significantly increased with increased antibiotic concentrations. The oxidation rate of pyruvate + proline from isolated mitochondria of the flight muscles of 1-day-old flies was significantly reduced at high doses of antibiotics. In parallel, the level of several metabolites, including TCA cycle intermediates, was reduced in antibiotics-treated flies. Overall, antibiotics provoked a system-wide alteration of the structure and physiology of flight muscles of the blow fly Ch. albiceps, and may have fitness consequences at the organism level. Environmental antibiotic pollution is likely to have unwanted cascading ecological effects of insect population dynamics and community structure.

Amyl salicylate (AS) is a fragrance massively used as a personal care product and following the discharged in wastewaters may end up in the aquatic environment representing a potential threat for the ecosystem and living organisms. AS was recently detected in water of the Venice Lagoon, a vulnerable area continuously subjected to the income of anthropogenic chemicals. The lagoon is a relevant area for mollusc farming, including the Mediterranean mussels (Mytilus galloprovincialis) having an important economic and ecological role. Despite high levels of AS occurred in water of the Lagoon of Venice, no studies investigated the possible consequences of AS exposures on species inhabiting this ecosystem to date. For the first time, we applied a multidisciplinary approach to investigate the potential effects of the fragrance AS on Mediterranean mussels. To reach such a goal, bioaccumulation, cellular, biochemical, and molecular analyses (RNA-seq and microbiota characterization) were measured in mussels treated for 7 and 14 days with different AS Venice lagoon environmental levels (0.1 and 0.5 μg L⁻¹). Despite chemical investigations suggested low AS bioaccumulation capability, cellular and molecular analyses highlighted the disruption of several key cellular processes after the prolonged exposures to the high AS concentration. Among them, potential immunotoxicity and changes in transcriptional regulation of pathways involved in energy metabolism, stress response, apoptosis and cell death regulations have been observed. Conversely, exposure to the low AS concentration demonstrated weak transcriptional changes and transient increased representation of opportunistic pathogens, as Arcobacter genus and Vibrio aestuarianus. Summarizing, this study provides the first overview on the effects of AS on one of the most widely farmed mollusk species.

In recent years, the cardiovascular toxicity of urban fine particulate matter (PM₂.₅) has sparked significant alarm. Mitochondria produce 90% of ATP and make up 30% of the volume of cardiomyocytes. Thus knowledge of myocardial mitochondrial dysfunction due to PM₂.₅ exposure is essential for further cardiotoxic effects. Here, the mechanism of PM₂.₅-induced cardiac hypertrophy through calcium overload and mitochondrial dysfunction was investigated in vivo and in vitro. Male and female BALB/c mice were given 1.28, 5.5, and 11 mg PM₂.₅/kg bodyweight weekly through oropharyngeal inhalation for four weeks and were assigned to low, medium, and high dose groups, respectively. PM₂.₅-induced myocardial edema and cardiac hypertrophy were detected in the high-dose group. Mitochondria were scattered and ruptured with abnormal ultrastructural morphology. In vitro experiments on human cardiomyocyte AC16 showed that exposure to PM₂.₅ for 24 h caused opened mitochondrial permeability transition pore --leading to excessive calcium production, decreased mitochondrial membrane potential, weakened mitochondrial respiratory metabolism capacity, and decreased ATP production. Nevertheless, the administration of calcium chelator ameliorated the mitochondrial damage in the PM₂.₅-treated group. Our in vivo and in vitro results confirmed that calcium overload under PM₂.₅ exposure triggered mTOR/AKT/GSK-3β activation, leading to mitochondrial bioenergetics dysfunction and cardiac hypertrophy.

Microorganisms are essential for modifying arsenic morphology, mobility, and toxicity. Still, knowledge of the microorganisms responsible for arsenic metabolism in specific arsenic-contaminated fields, such as metallurgical plants is limited. We sampled on-field soils from three depths at 70 day intervals to explore the distribution and transformation of arsenic in the soil. Arsenic-metabolizing microorganisms were identified from the mapped gene sequences. Arsenic metabolism pathways were constructed with metagenomics and AsChip analysis (a high-throughput qPCR chip for arsenic metabolism genes). It has been shown in the result that 350 genera of arsenic-metabolizing microorganisms carrying 17 arsenic metabolism genes in field soils were identified, as relevant to arsenic reduction, arsenic methylation, arsenic respiration, and arsenic oxidation, respectively. Arsenic reduction genes were the only genes shared by the 10 high-ranking arsenic-metabolizing microorganisms. Arsenic reduction genes (arsABCDRT and acr3) accounted for 73.47%–78.11% of all arsenic metabolism genes. Such genes dominated arsenic metabolism, mediating the reduction of 14.11%–19.86% of As(V) to As(III) in 0–100 cm soils. Arsenic reduction disrupts microbial energy metabolism, DNA replication and repair and membrane transport. Arsenic reduction led to a significant decrease in the abundance of 17 arsenic metabolism genes (p < 0.0001). The critical role of arsenic-reducing microorganisms in the migration and transformation of arsenic in metallurgical field soils, was emphasized with such results. These results were of pronounced significance for understanding the transformation behavior of arsenic and the precise regulation of arsenic in field soil.

The formation of tailings ponds depends on the long-term accumulation of tailing and high terrain. Its seepage pollution characteristics may have gradient variations on spatiotemporal scales. Used three nearby metal tailings ponds with different service times, we aimed to reveal seepage pollution trends on spatiotemporal scales and the response of soil microbial community. The results showed that the degree of seepage pollution was negatively correlated with the distance from the tailings pond on the spatial scale, while the seepage pollution showed higher levels in tailings ponds with longer service times on the temporal scale (RI = 248.04–2109.85). The pollution effect of seepage persisted after the tailings pond was discontinued (RI = 226.72). Soil microbial diversity increased with spatial scale expansion. The proportion of Actinomyces gradually increased and Proteobacteria decreased. Cr (r = 0.21) and Fe (r = 0.22) contributed more to the microbial community changes. Functional predictions showed that pathways related to signal transduction and energy metabolism were more abundant in the tailings pond. In contaminated areas, the proportion of nitrate respiration and cellulolysis functional communities had decreased, and some potentially pathogenic human taxa had accumulated. These results emphasized that there was pollution accumulation on temporal scale and pollution dispersion on spatial scale around tailings ponds, and the response of the microbial community further illustrated these trends.

With the widespread occurrence and accumulation of plastic waste in the world, plastic pollution has become a serious threat to ecosystem and ecological security, especially to estuarine and coastal areas. Understanding the impacts of changing nanoplastics concentrations on aquatic organisms living in these areas is essential for revealing the ecological effects caused by plastic pollution. In the present study, we revealed the effects of exposure to gradient concentrations (0.005, 0.05, 0.5 and 50 mg/L) of 75 nm polystyrene nanoplastics (PS-NPs) for 48 h on metabolic processes in muscle tissue of a bivalve, the razor clam Sinonovacula constricta, via metabolomic and transcriptomic analysis. Our results showed that PS-NPs caused dose-dependent adverse effects on energy reserves, membrane lipid metabolism, purine metabolism and lysosomal hydrolases. Exposure to PS-NPs reduced energy reserves, especially lipids. Membrane lipid metabolism was sensitive to PS-NPs with contents of phosphocholines (PC), phosphatidylethanolamines (PE) and phosphatidylserines (PS) increasing and degradation being inhibited in all concentrations. High concentrations of PS-NPs altered the purine metabolism via increasing contents of guanosine triphosphate (GTP) and adenine, which may be needed for DNA repair, and consuming inosine and hypoxanthine. During exposure to low concentrations of PS-NPs, lysosomal hydrolases in S. constricta, especially cathepsins, were inhibited while this influence was improved transitorily in 5 mg/L of PS-NPs. These adverse effects together impacted energy metabolism in S. constricta and disturbed energy homeostasis, which was manifested by the low levels of acetyl-CoA in high concentrations of PS-NPs. Overall, our results revealed the effects of acute exposure to gradient concentrations of PS-NPs on S. constricta, especially its metabolic process, and provide perspectives for understanding the toxicity of dynamic plastic pollution to coastal organisms and ecosystem.

Biomonitoring of aquatic environments requires new tools to characterize the effects of pollutants on living organisms. Zebra mussels (Dreissena polymorpha) from the same site in north-eastern France were caged for two months, upstream and downstream of three wastewater treatment plants (WWTPs) in the international watershed of the Meuse (Charleville-Mézières “CM” in France, Namur “Nam” and Charleroi “Cr” in Belgium). The aim was to test ¹H-NMR metabolomics for the assessment of water bodies’ quality. The metabolomic approach was combined with a more “classical” one, i.e., the measurement of a range of energy biomarkers: lactate dehydrogenase (LDH), lipase, acid phosphatase (ACP) and amylase activities, condition index (CI), total reserves, electron transport system (ETS) activity and cellular energy allocation (CEA). Five of the eight energy biomarkers were significantly impacted (LDH, ACP, lipase, total reserves and ETS), without a clear pattern between sites (Up and Down) and stations (CM, Nam and Cr). The metabolomic approach revealed variations among the three stations, and also between the upstream and downstream of Nam and CM WWTPs. A total of 28 known metabolites was detected, among which four (lactate, glycine, maltose and glutamate) explained the observed metabolome variations between sites and stations, in accordance with chemical exposure levels. Metabolome changes suggest that zebra mussel exposure to field contamination could alter their osmoregulation and anaerobic metabolism capacities. This study reveals that lactate is a potential biomarker of interest, and ¹H-NMR metabolomics can be an efficient approach to assess the health status of zebra mussels in the biomonitoring of aquatic environments.

Strobilurin fungicides have been frequently detected in aquatic environments and can induce mitochondrial toxicity to non-target aquatic organisms. However, the derived toxicity and subsequent mechanisms related to their adverse effects are not fully elucidated. In the present study, we compared the mitochondrial and developmental toxicity of azoxystrobin, pyraclostrobin, and trifloxystrobin using zebrafish embryo/larvae. The results showed that all three strobilurins inhibited mitochondrial and non-mitochondrial respiration (the potency is pyraclostrobin ≈ trifloxystrobin > azoxystrobin). Behavioral changes indicated that sublethal doses of pyraclostrobin and azoxystrobin caused hyperactivity of zebrafish larvae in dark cycles, whereas trifloxystrobin resulted in hypoactivity of zebrafish larvae. In addition, pyraclostrobin exposure impaired the inflation of swim bladder, and caused down-regulation of annexin A5 (anxa5) mRNA levels, and up-regulated transcript levels of pre-B-cell leukemia homeobox 1a (pbx1a); conversely, azoxystrobin and trifloxystrobin did not cause detectable effects with swim bladder inflation. Molecular docking results indicated that azoxystrobin had higher interacting potency with iodotyrosine deiodinase (IYD), prolactin receptor (PRLR), antagonistic conformation of thyroid hormone receptor β (TRβ) and glucocorticoid receptor (GR) compared to pyraclostrobin and trifloxystrobin; pyraclostrobin and azoxystrobin were more likely to interact with the antagonistic conformation of TRβ and GR, respectively. These results may partially explain the different effects observed in behavior and swim bladder inflation, and also point to potential endocrine disruption induced by these strobilurins. Taken together, our study revealed that all three strobilurins alter mitochondrial bioenergetics and cause developmental toxicity. However, the toxic phenotypes and underlying mechanisms of each chemical may differ, and this requires further investigation. Pyraclostrobin showed higher mitochondrial toxicity at lethal doses and higher developmental toxicity at sublethal doses compared to the two other strobilurins tested. These results provide novel information for toxicological study as well as risk assessment of strobilurin fungicides.

Microplastics (MPs) are widely found in coastal areas and oceans worldwide. The MPs are environmentally concerning due to their bioavailability and potential impacts on a wide range of marine biota, so assessing their impact on the biota has become an urgent research priority. In the present study, we exposed Crassostrea gigas oysters to irregular MPs of two polymer types (polyethylene (PE) and polyethylene terephthalate (PET)) at concentrations of 10 and 1000 μg L⁻¹ for 21 days. Accumulation of MPs, changes in metabolic enzyme activity, and histological damage were evaluated, and metabolomics analysis was conducted. Results demonstrated that PE and PET MPs were detected in the gills and digestive gland following exposure to both tested concentrations, confirming ingestion of MPs by the organisms. Moreover, both PE and PET MPs inhibited lipid metabolism, while energy metabolism enzyme activities were activated in the oysters. Histopathological damage of exposed oysters was also observed in this study. Integrated biomarker response (IBR) results showed that MPs toxicity increased with increasing MPs concentration, and the toxic effects of PET MPs on oysters was greater than PE MPs. In addition, metabolomics analysis suggested that MPs exposure induced alterations in metabolic profiles in oysters, with changes in energy metabolism and inflammatory responses. This study reports new insights into the consequences of MPs exposure in marine bivalves at environmentally relevant concentrations, providing valuable information for ecological risk assessment of MPs in a realistic conditions.