Ibuprofen as an emerging pollutant on non-target aquatic invertebrates: Effects on Chironomus riparius

Promoting effects of lipophilic pollutants on the reproductive toxicity of proteinophilic pollutants to Daphnia magna under chronic exposure

Lipophilic and proteinophilic toxic organic pollutants often coexist in aquatic environments. However, the toxic effects of these two types of pollutants on aquatic organisms under chronic co-exposure are poorly understood. In this study, the effects of lipophilic pollutants (pyrene and PCB 28) on the reproductive toxicity of proteinophilic pollutants (cyromazine) to Daphnia magna over a 28-d exposure period were investigated by analyzing alterations in developmental and reproductive endpoints, bioaccumulation, and the transcriptome. The results revealed that the bioaccumulation of lipophilic pollutants was inhibited by each other and that their bioaccumulation was not affected by cyromazine. However, lipophilic pollutants promoted the bioaccumulation of cyromazine in D. magna by 48.1%-220.0% through increasing the protein content by 11.1%-71.9% due to the downregulated gene expression associated with the decomposition process of proteins. The higher concentrations of cyromazine in the combined group caused greater disruption of the transcriptome related to the energy metabolism progression, reproduction, and development of D. magna compared with the cyromazine single exposure group. Hence, lipophilic pollutants enhanced the adverse effects on the growth, reproductive time and capacity, and intrinsic growth rate of D. magna induced by proteinophilic pollutants, and a synergistic effect occurred between lipophilic and proteinophilic pollutants. This study provides new insights into the ecological risks of lipophilic and proteinophilic pollutant mixtures in aquatic environments.

Insect immunity in the Anthropocene

Anthropogenic activities result in global change, including climate change, landscape degradation and pollution, that can alter insect physiology and immune defences. These changes may have contributed to global insect decline and the dynamics of insect-transmitted diseases. The ability of insects to mount immune responses upon infection is crucial for defence against pathogens and parasites. Suppressed immune defences reduce fitness by causing disease-driven mortality and elevated immune responses reduce energy available to invest in other fitness traits such as reproduction. Understanding the impact of anthropogenic factors on insect-pathogen interactions is therefore key to determining the contribution of anthropogenic global change to pathogen-driven global insect decline and the emergence and transmission of insect-borne diseases. Here, we synthesise evidence of the impact of anthropogenic factors on insect immunity. We found evidence that anthropogenic factors, such as insecticides and heavy metals, directly impacting insect immune responses by inhibiting immune activation pathways. Alternatively, factors such as global warming, heatwaves, elevated CO2 and landscape degradation can indirectly reduce insect immune responses via reducing the energy available for immune function. We further review how anthropogenic factors impact pathogen clearance and contribute to an increase in vector-borne diseases. We discuss the fitness cost of anthropogenic factors via pathogen-driven mortality and reduced reproductive output and how this can contribute to species extinction. We found that most research has determined the impact of a single anthropogenic factor on insect immune responses or pathogen resistance. We recommend studying the combined impact of multiple stressors on immune response and pathogen resistance to understand better how anthropogenic factors affect insect immunity. We conclude by highlighting the importance of initiatives to mitigate the impact of anthropogenic factors on insect immunity, to reduce the spread of vector-borne diseases, and to protect vulnerable ecosystems from emerging diseases.

Multigenerational effects of individual and binary mixtures of two commonly used NSAIDs on Daphnia carinata

Pharmaceuticals, including non-steroidal anti-inflammatory drugs (NSAIDs) like ibuprofen (IBU) and naproxen (NPX), are widely used for medical purposes but have also become prevalent environmental contaminants. However, there is limited understanding of their effects on aquatic organisms, especially regarding multigenerational and mixture exposures. This study aimed to evaluate the toxicological impacts of ibuprofen and naproxen, individually and in combination, on three generations of Daphnia carinata, a freshwater organism. Daphnids were exposed to environmentally relevant concentrations of ibuprofen and naproxen (0.1, 0.5, 2.5 µg/L and 0.1 + 0.1, 0.1 + 0.5, 2.5 + 2.5 µg/L) throughout multiple generations. The endpoints assessed were reproduction, body size, reproduction recovery, and behaviour. The results revealed that ibuprofen and naproxen negatively impacted reproduction, reducing reproduction output across generations. Additionally, daphnids exhibited changes in body size, with significant alterations observed in the F2 and F3 generations. Male individuals and ephippium were also present at all concentrations throughout all generations. Although reproduction recovery could not be observed in daphnids after one generation in clean water, the average number of neonates was higher in a few treatments in generation F4 compared to generation F3. In addition, binary mixtures of the drugs showed synergistic effects on daphnids' reproduction for most generations. The multigenerational approach provided valuable insights into the long-term effects of these NSAIDs on reproduction success and population dynamics. This study contributes to understanding the ecotoxicity of ibuprofen and naproxen in aquatic organisms, particularly in a multigenerational context and in the presence of mixture exposures.

Small heat shock proteins as relevant biomarkers for anthropogenic stressors in earthworms

Anthropogenic stressors in terrestrial ecosystems require focused research on adaptive responses in soil organisms such as Eisenia fetida, a model earthworm species. We analyzed the gene expression of five small heat shock proteins (sHSPs) in response to various stressors: heat stress (31 and 35 °C), desiccation (10 % and 20 % humidity), and chemical exposure (bisphenol A and endosulfan) under standard and elevated temperatures. Under moderate heat (31 °C), early upregulation of sHSP transcripts suggests their involvement in initial stress responses, possibly mitigating protein aggregation. At the higher temperature (35 °C), three sHSPs served as a defense against severe protein aggregation, a significant finding as previous studies identified only one activated heat shock protein (HSP70) in E. fetida under similar conditions. Desiccation stress at 10 % humidity activated more sHSPs than at 20 % humidity, and the expression profile at 10 % humidity closely resembled that observed under heat stress, suggesting overlapping adaptation pathways. Heat combined with chemical stress, particularly endosulfan, elevated sHSP transcription and underscored the potential of these proteins as biomarkers in multi-stressor environments. Monomeric sHSPs from E. fetida, which share homology with human sHSPs, showed the highest activity across all stressors, suggesting their key role in earthworm adaptation.

Pharmaceutical Pollutants: Ecotoxicological Impacts and the Use of Agro-Industrial Waste for Their Removal from Aquatic Environments

Medicines are pharmaceutical substances used to treat, prevent, or relieve symptoms of different diseases in animals and humans. However, their large-scale production and use worldwide cause their release to the environment. Pharmaceutical molecules are currently considered emerging pollutants that enter water bodies due to inadequate management, affecting water quality and generating adverse effects on aquatic organisms. Hence, different alternatives for pharmaceuticals removal from water have been sought; among them, the use of agro-industrial wastes has been proposed, mainly because of its high availability and low cost. This review highlights the adverse ecotoxicological effects related to the presence of different pharmaceuticals on aquatic environments and analyzes 94 investigations, from 2012 to 2024, on the removal of 17 antibiotics, highlighting sulfamethoxazole as the most reported, as well as 6 non-steroidal anti-inflammatory drugs (NSAIDs) such as diclofenac and ibuprofen, and 27 pharmaceutical drugs with different pharmacological activities. The removal of these drugs was evaluated using agro-industrial wastes such as wheat straw, mung bean husk, bagasse, bamboo, olive stones, rice straw, pinewood, rice husk, among others. On average, 60% of the agro-industrial wastes were transformed into biochar to be used as a biosorbents for pharmaceuticals removal. The diversity in experimental conditions among the removal studies makes it difficult to stablish which agro-industrial waste has the greatest removal capacity; therefore, in this review, the drug mass removal rate (DMRR) was calculated, a parameter used with comparative purposes. Almond shell-activated biochar showed the highest removal rate for antibiotics (1940 mg/g·h), while cork powder (CP) (10,420 mg/g·h) showed the highest for NSAIDs. Therefore, scientific evidence demonstrates that agro-industrial waste is a promising alternative for the removal of emerging pollutants such as pharmaceuticals substances.

Toxicological study on ibuprofen and selenium in freshwater mussel Lamellidens marginalis and exploring the microbial cytochrome through modelling and quantum mechanics approaches for its toxicity degradation in contaminated environment

Toxicological stress in aquatic organisms is caused by the discharge of hundreds of toxic pollutants and contaminants among which the current study concentrates on the toxic effect of non-steroidal anti-inflammatory drug ibuprofen (IBF) and the trace element selenium (Se). In this study, IBF and Se toxicity on freshwater mussel Lamellidens marginalis was studied for 14 days, and in silico predictions for their degradation were made using Molecular modelling and Quantum Mechanical approaches. The degrading propensity of cytochrome c oxidase proteins from Trametes verticillatus and Thauera selenatis (Turkey tail fungi and Gram-negative bacteria) is examined into atom level. The results of molecular modelling study indicate that ionic interactions occur in the T. selenatis-HEME bound complex by Se interacting directly with HEME, and in the T. versicolor-HEME bound complex by IBF bound to a nearby region of HEME. Experimental and theoretical findings suggest that, the toxicological effects of Se and IBF pollution can be reduced by bioremediation with special emphasis on T. versicolor, and T. selenatis, which can effectively interact with Se and IBF present in the environment and degrade them. Besides, this is the first time in freshwater mussel L. marginalis that ibuprofen and selenium toxicity have been studied utilizing both experimental and computational methodologies for their bioremediation study.

New insights about the toxicity of 2,4-D: Gene expression analysis reveals modulation on several subcellular responses in Chironomus riparius

Herbicides are the main class of pesticides applied in crops and are capable of polluting the surrounding freshwater system; thus, understanding their impact on non-target species, whose mechanism of action is not described, helps to elucidate the real risks of these pollutants to the environment. 2,4-dichlorophenoxyacetic acid (2,4-D) is frequently detected in water and, due to its persistence, poses a risk to wildlife. In this way, the present work aimed to describe the implication of exposure to concentrations of 2,4-D already reported in aquatic environments in several physiological mechanisms of C. riparius at molecular and biochemical levels. To achieve this, bioassays were conducted with fourth instar larvae exposed to three concentrations of 2,4-D (0.1, 1.0, and 7.5 μg L-1). Larvae were collected after 24 and 96 h of exposure, and the expression of 42 genes, related to six subcellular mechanisms, was assessed by Real-Time PCR (RT-PCR). Besides, the activity of the enzymes catalase (CAT), glutathione S-transferase (GST), and acetylcholinesterase (AChE) was determined. The main metabolic route altered after exposure to 2,4-D was the endocrine system (mainly related to 20-hydroxyecdysone and juvenile hormone), confirming its endocrine disruptor potential. Four of the eleven stress response genes studied were down-regulated, and later exposure modulated DNA-repair genes suggesting genotoxic capacity. Moreover, only one gene from each detoxification phase was modulated at short exposure to 1.0 μg L-1. The molecular responses were not dose-dependent, and some early responses were not preserved after 96 h, indicating a transient response to the herbicide. Exposure to 2,4-D did not alter the activity of CAT, GST, and AChE enzymes. The responses described in this study reveal new mechanistic pathways of toxicity for 2,4-D in non-target organisms and highlight potential ecological consequences for chironomids in aquatic systems at the edges of agricultural fields.

Tricks and tracks of prevalence, occurrences, treatment technologies, and challenges of mixtures of emerging contaminants in the environment: With special emphasis on microplastic

This paper aims to emphasize the occurrence of various emerging contaminant (EC) mixtures in natural ecosystems and highlights the primary concern arising from the unregulated release into soil and water, along with their impacts on human health. Emerging contaminant mixtures, including pharmaceuticals, personal care products, dioxins, polychlorinated biphenyls, pesticides, antibiotics, biocides, surfactants, phthalates, enteric viruses, and microplastics (MPs), are considered toxic contaminants with grave implications. MPs play a crucial role in transporting pollutants to aquatic and terrestrial ecosystems as they interact with the various components of the soil and water environments. This review summarizes that major emerging contaminants (ECs), like trimethoprim, diclofenac, sulfamethoxazole, and 17α-Ethinylestradiol, pose serious threats to public health and contribute to antimicrobial resistance. In addressing human health concerns and remediation techniques, this review critically evaluates conventional methods for removing ECs from complex matrices. The diverse physiochemical properties of surrounding environments facilitate the partitioning of ECs into sediments and other organic phases, resulting in carcinogenic, teratogenic, and estrogenic effects through active catalytic interactions and mechanisms mediated by aryl hydrocarbon receptors. The proactive toxicity of ECs mixture complexation and, in part, the yet-to-be-identified environmental mixtures of ECs represent a blind spot in current literature, necessitating conceptual frameworks for assessing the toxicity and risks with individual components and mixtures. Lastly, this review concludes with an in-depth exploration of future scopes, knowledge gaps, and challenges, emphasizing the need for a concerted effort in managing ECs and other organic pollutants.

Environmentally Relevant Concentrations of the Insecticide Fipronil Modulated Molecular Response in Chironomus riparius

Pesticides employed worldwide for crop protection easily reach aquatic systems, which act as the main reservoirs, and become a risk factor for aquatic fauna. Fipronil is a broad-spectrum insecticide acting on the insect nervous system; however, other effects and systems unrelated to this mechanism could be affected in non-target organisms. Thus, the present study aimed to assess the impact of fipronil on the suborganismal response (gene expression and enzymatic activity) of Chironomus riparius larvae as a model organism in ecotoxicology. To this end, short-term toxicity tests were carried out with fourth-instar larvae exposed to 0.001, 0.01, and 0.1 µg L-1 of fipronil for 24 and 96 h. Messenger RNA levels of 42 genes related to diverse metabolic pathways were analyzed by real-time polymerase chain reaction, complemented with catalase (CAT), glutathione S-transferase (GST), and acetylcholinesterase (AChE) activities. Few effects were observed at 24 h; however, after longer exposure (96 h), genes involved in the endocrine, detoxification, stress, and immune response pathways were altered. Moreover, fipronil at 96 h increased CAT and GST activity at 0.01 µg L-1 and AChE at the highest concentrations. The results demonstrate that even low environmentally relevant fipronil concentrations can modulate the molecular response of several cellular pathways in C. riparius after short-term exposure. These results bring new information about the underlying response of fipronil and its mode of action on a key aquatic invertebrate. Despite no effects on mortality, strong modulation at the suborganismal level emphasizes the advantage of biomarkers as early damage responses and the harmful impact of this pesticide on freshwater organisms. Environ Toxicol Chem 2024;43:405-417. © 2023 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

Thermally-activated gelatin-chitosan-MOF hybrid aerogels for efficient removal of ibuprofen and naproxen

Nonsteroidal anti-inflammatory drugs (NSAIDs) are one of the most frequently used drugs and have been frequently detected in aquatic environments. This paper demonstrates a thermally-activated gelatin-chitosan and amine-functionalized metal-organic framework (UiO-66-NH2) aerogel (CGC-MOF), which was successfully synthesized for the efficient removal of ibuprofen (IBP) and naproxen (NPX). Various characterization tools were used to systematically analyze the microstructure and physicochemical properties of the synthesized aerogel. In addition, the effect of key reaction parameters as well as batch and continuous-flow fixed-bed column experiments were carried out to elucidate the adsorption process. Several functional groups in the biopolymer network, combined with excellent MOF properties, synergistically couple to form an adsorbent with great performance. The mesoporous aerogel activated at 200 °C (CGC-MOF200) exhibited a high specific surface area (819.6 m2/g) that is valuable in providing abundant adsorption active sites that facilitate the efficient adsorption of IBP and NPX. CGC-MOF200 exhibited an excellent removal of IBP and NPX, accounting to 99.28 % and 96.39 %, respectively. The adsorption process followed the pseudo-second-order kinetics and the Freundlich isotherm models, suggesting heterogeneous and chemisorption adsorption processes. Overall, this work provides new and valuable insights into the development of a promising biopolymer-MOF composite aerogel for environmental remediation.

Functional characterization of an efficient ibuprofen-mineralizing bacterial consortium

Ibuprofen (IBU) is a widely used non-steroidal anti-inflammatory drug (NSAID), which has attracted widespread attention due to its high frequency of environmental detection, non-degradability and potential ecological risks. However, little is known about the functional characterization of the highly efficient IBU-mineralizing consortium. In this study, an IBU-mineralizing consortium C6 was obtained by continuous enrichment of the original consortium C1 accumulated the metabolite of 2-Hydroxyibuprofen (2HIBU). Methylobacter, Pseudomonas, and Dokdonella spp. were significantly enriched in the consortium C6. Streptomyces sp. had a relative abundance of about 0.01 % in the consortium C1 but extremely low (< 0.001 %) in the consortium C6. Subsequently, two IBU degraders, Streptomyces sp. D218 and Pseudomonas sp. M20 with detection of 2HIBU or not, were isolated from the consortia C1 and C6, respectively. These results imply that the degradation of IBU in the consortia C1 and C6 may be mainly mediated by key players of Streptomyces and Pseudomonas, respectively. This study showed that the composition of the core functional strains of the bacterial community structure was changed by continuous enrichment, which affected the degradation process of IBU. These findings provide new insights into our understanding of the biotransformation process of NSAIDs and provide valuable strain resources for bioremediation.

Ionic Liquid-Based Green Emulsion Liquid Membrane for the Extraction of the Poorly Soluble Drug Ibuprofen

Ibuprofen (Ibf) is a biologically active drug (BADs) and an emerging contaminant of concern (CECs) in aqueous streams. Due to its adverse effects upon aquatic organisms and humans, the removal and recovery of Ibf are essential. Usually, conventional solvents are employed for the separation and recovery of ibuprofen. Due to environmental limitations, alternative green extracting agents need to be explored. Ionic liquids (ILs), emerging and greener alternatives, can also serve this purpose. It is essential to explore ILs that are effective for recovering ibuprofen, among millions of ILs. The conductor-like screening model for real solvents (COSMO-RS) is an efficient tool that can be used to screen ILs specifically for ibuprofen extraction. The main objective of this work was to identify the best IL for the extraction of ibuprofen. A total of 152 different cation-anion combinations consisting of eight aromatic and non-aromatic cations and nineteen anions were screened. The evaluation was based upon activity coefficients, capacity, and selectivity values. Furthermore, the effect of alkyl chain length was studied. The results suggest that quaternary ammonium (cation) and sulfate (anion) have better extraction ability for ibuprofen than the other combinations tested. An ionic liquid-based green emulsion liquid membrane (ILGELM) was developed using the selected ionic liquid as the extractant, sunflower oil as the diluent, Span 80 as the surfactant, and NaOH as the stripping agent. Experimental verification was carried out using the ILGELM. The experimental results indicated that the predicted COSMO-RS and the experimental results were in good agreement. The proposed IL-based GELM is highly effective for the removal and recovery of ibuprofen.

Ibuprofen: Toxicology and Biodegradation of an Emerging Contaminant

The anti-inflammatory drug ibuprofen is considered to be an emerging contaminant because of its presence in different environments (from water bodies to soils) at concentrations with adverse effects on aquatic organisms due to cytotoxic and genotoxic damage, high oxidative cell stress, and detrimental effects on growth, reproduction, and behavior. Because of its high human consumption rate and low environmental degradation rate, ibuprofen represents an emerging environmental problem. Ibuprofen enters the environment from different sources and accumulates in natural environmental matrices. The problem of drugs, particularly ibuprofen, as contaminants is complicated because few strategies consider them or apply successful technologies to remove them in a controlled and efficient manner. In several countries, ibuprofen's entry into the environment is an unattended contamination problem. It is a concern for our environmental health system that requires more attention. Due to its physicochemical characteristics, ibuprofen degradation is difficult in the environment or by microorganisms. There are experimental studies that are currently focused on the problem of drugs as potential environmental contaminants. However, these studies are insufficient to address this ecological issue worldwide. This review focuses on deepening and updating the information concerning ibuprofen as a potential emerging environmental contaminant and the potential for using bacteria for its biodegradation as an alternative technology.

Activation of peroxymonosulfate for degrading ibuprofen via single atom Cu anchored by carbon skeleton and chlorine atom: The radical and non-radical pathways

Single atomic Cu catalysts (SACs Cu@C) anchored by carbon skeleton and chlorine atom was synthesized by hydrolyzing Cu-MOFs and then pickled by aqua-regia to remove Cu nanoparticles (NPs Cu). Comparative characterizations revealed that SACs Cu@C was a hierarchically porous nanostructure and Cu dispersed uniformly throughout the carbon skeletons. With less active components, SACs Cu@C behaved better in activating PMS over NPs Cu@C on ibuprofen removal (91.3 % versus 30.2 % in 30 min). Two Cu coordination environments were found by EXAF and DFT calculation, including four-coordinated Cu with 4C atoms and six-coordinated Cu with 4Cu and 2Cl atoms. The obvious interfacial electron delivery between PMS and SACs Cu@C was found, which was enhanced by Cl atom. Cu(I)/Cu(II) redox cycle would donate electron to peroxy bond of PMS for generating OH, SO₄^- and O₂^-. But electron transferred in opposite direction when PMS bonded to Cu atom through its terminal oxygen atom in sulfate, which formed ¹O₂. IBP degradation proceeded through both radical and non-radical route. IBP degradation was inhibited with the presence of TBA, methanol and furfuryl alcohol but accelerated by p-BQ, which could accelerate OH generation. Two degradation pathways were deducted. This study provided a new insight into catalysts designed for PMS activation.

Eicosanoid Biosynthesis in Male Reproductive Development: Effects of Perinatal Exposure to NSAIDs and Analgesic Drugs

Increasing rates of infertility associated with declining sperm counts and quality, as well as increasing rates of testicular cancer are contemporary issues in the United States and abroad. These conditions are part of the Testicular Dysgenesis Syndrome, which includes a variety of male reproductive disorders hypothesized to share a common origin based on disrupted testicular development during fetal and neonatal stages of life. Male reproductive development is a highly regulated and complex process that relies on an intricate coordination between germ, Leydig, and Sertoli cells as well as other supporting cell types, to ensure proper spermatogenesis, testicular immune privilege, and endocrine function. The eicosanoid system has been reported to be involved in the regulation of fetal and neonatal germ cell development as well as overall testicular homeostasis. Moreover, non-steroidal anti-inflammatory drugs (NSAIDs) and analgesics with abilities to block eicosanoid synthesis by targeting either or both isoforms of cyclooxygenase enzymes, have been found to adversely affect male reproductive development. This review will explore the current body of knowledge on the involvement of the eicosanoid system in male reproductive development, as well as discuss adverse effects of NSAIDs and analgesic drugs administered perinatally, focusing on toxicities reported in the testis and on major testicular cell types. Rodent and epidemiological studies will be corroborated by findings in invertebrate models for a comprehensive report of the state of the field, and to add to our understanding of the potential long-term effects of NSAID and analgesic drug administration in infants.

Molecular biomarkers as tool for early warning by chlorpyrifos exposure on Alpine chironomids

Pesticides used in agriculture can be transported at a medium-high distance due to the drift effect, reaching even remote areas as mountain regions, glaciers, and snow cover. With the melting process, pesticides enter freshwater glacier ecosystems, becoming a threat to wildlife fauna, mainly dominated by Diptera Chironomidae. Chlorpyrifos (CPF), as one of the most commonly used pesticides in alpine vineyards and apple orchards, is frequently detected in icemelt waters. We selected as target species, larvae of the cold stenothermal chironomid Diamesa zernyi, collected in two glacier-fed streams (Presena and Amola) in the Italian Alps. Firstly, a de novo transcriptome was obtained, and secondly, a gene array was designed to study the molecular response of a wild population of D. zernyi exposed to three sub-lethal CPF concentrations corresponding to 1/100 LC10 (0.011 μg/L), 1/10 LC10 (0.11 μg/L), and LC10 (1.1 μg/L), for 24 h. The sub-organismal response was evaluated by Real-Time Polymerase Chain Reaction (RT-PCR), employing 40 genes related to essential metabolic routes as future candidates for biomarkers in wildlife chironomids. After 24 h, the endocrine system (E75, E93, EcR, and Met), detoxification response (GSTO3, GSTS1), and stress response (hsp75, hsp83, HYOU1) were altered. CPF seems to act as an endocrine disruptor and could lead to defective larval development, disrupted cellular homeostasis through heat shock proteins (HSPs) alteration (defective protein folding and mitochondrial functions), as well as oxidative damage (confirmed by increased GST expression). For the first time, molecular studies detected early alarm signals in wildlife in glacier environments. Our findings confirm the high environmental risk of CPF affecting aquatic insect metabolism and raise the level of concern about this pesticide in high altitude water bodies, generally considered pristine. Furthermore, this study emphasizes the incipient need to use non-model organisms for the evaluation of natural ecosystems. We also highlight the demand for research into new molecular biomarkers, and the importance of including molecular approaches in toxicology evaluations to detect the early adverse effects of pollutants.

Persistent pesticides: effects of endosulfan at the molecular level on the aquatic invertebrate Chironomus riparius

Although banned in multiple areas, due to its persistence in the environment, endosulfan constitutes a significant environmental concern. In this work, fourth instar Chironomus riparius larvae were exposed at environmentally relevant endosulfan concentrations of 0.1, 1, and 10 μg/L for 24 h to analyze the possible effects of this acaricide on gene expression and enzymatic activity. Transcriptional changes were studied through the implementation of a real-time polymerase chain reaction array with 42 genes related to several metabolic pathways (endocrine system, detoxification response, stress response, DNA reparation, and immune system). Moreover, glutathione-S-transferase (GST), phenoloxidase (PO), and acetylcholinesterase (AChE) activities were assessed. The five pathways were differentially altered by endosulfan exposure with significant changes in the E93, Dis, MAPR, Met, InR, GSTd3, GSTt3, MRP1, hsp70, hsp40, hsp24, ATM, PARP, Proph, and Def genes. Besides, all of the measured enzymatic activities were modified, with increased activity of GST, followed by PO and AChE. In summary, the results reflected the effects provoked in C. riparius at molecular level despite the absence of lethality. These data raise concerns about the strong alteration on different metabolic routes despite the low concentrations used. Therefore, new risk assessment strategies should consider include the effects at the sub-organismal level as endpoints in addition to the classical ecologically relevant parameters (such as survival). This endeavor will facilitate a comprehensive evaluation of toxicants in the environment.