Aquatic Toxicology最新文献

This study focuses on the mixture effects of two classes of common aquatic contaminants, microcystin-LR (MCLR) and benzo[a]pyrene (BaP), on detoxification in a fish liver cell line (PLHC-1). Cells were exposed to non-cytotoxic concentrations, either MCLR (0.01, 1 µM), BaP (0.01, 0.1, 1 µM), or mixtures of both chemicals for 1 to 48 h. Functions and regulations of cytochrome P450 1A (CYP1A) and P-glycoprotein (Pgp) were analyzed. In addition, cytotoxicity was analyzed to ensure non-cytotoxic effects of any of the treatments. Exposure to MCLR, BaP individually or in different mixture combinations induced CYP1A enzyme activity and CYP1A mRNA expression with differences between individual and mixed exposures. An antagonistic mixture effect was seen on the induction of CYP1A enzyme activity. The half maximal inhibition concentration of BaP on CYP1A activity was 1.7 µM, implying weak inhibition by BaP. In contrast, MCLR had no inhibitory effect, suggesting that the antagonistic mixture effect is not due to inhibition of the CYP1A enzyme by MCLR. However, a synergistic mixture effect was seen on induction of CYP1A mRNA levels at early exposure times (1 and 3 h). At 6 h or longer exposures times, only the highest BaP concentration tested (1 µM) induced CYP1A mRNA expression. Function and regulation of Pgp were not significantly affected in any of the exposure experiments. Besides, none of tested concentrations or mixtures caused cytotoxicity. This study suggests mixture effects between MCLR and BaP at lower concentrations (maximum 1 µM) on function and regulation of CYP1A in a fish liver cell line, providing new insights into the potential adverse mixture effects between these two different classes of aquatic contaminants.

Levonorgestrel (LNG), a common synthetic progestogen, has emerged as an endocrine-disrupting contaminant in aquatic ecosystems. Although recent studies have recognized its androgenic effects, there exist critical gaps in understanding its influence on growth and associated molecular mechanisms. The processes driving anal fin elongation in mosquitofish (Gambusia affinis) following exposure to progestogens, such as LNG, remain poorly characterized. To address these knowledge gaps, we investigated LNG-induced androgenic effects on growth and the molecular basis of anal fin masculinization in adult female mosquitofish exposed to environmentally relevant LNG concentrations (500 ng/L) over a four-week period. Comprehensive physiological and morphological assessments (e.g., Fulton's condition factor, gonadosomatic index, and anal fin/skeletal analyses) revealed significant masculinization in LNG-exposed females. Transcriptomic profiling of anal fin tissue demonstrated that LNG-mediated masculinization and elongation at 500 ng/L were associated with the activation of the transforming growth factor-beta (TGF-β) and bone morphogenetic protein (BMP) signaling pathways. The exposure altered the transcriptional levels of key osteoblast- and osteoclast-related genes (i.e., sp7, col10a1, and nfatc1), implicating dysregulated bone remodeling in fin structural changes. Androgen receptor (ar) expression in anal fin tissue remained unchanged, suggesting that LNG's androgenic effects occurred independently of direct ar transcriptional modulation in this tissue. This study provides the first evidence that LNG disrupts bone morphogenetic and sex-related gene transcription, driving anal fin masculinization in female mosquitofish. These findings advance our understanding of LNG's androgenic impacts and propose the mosquitofish anal fin as a potential biomarker for endocrine disruption. By elucidating molecular pathways linking LNG exposure to morphological changes, this study paves the way for assessing the ecological risks of progestogen pollution in aquatic ecosystems.

Wildlife is exposed to contaminants in their environment and also to other stressors such as cold or low food availability. The consequences of exposure to some contaminants and stressors have been studied to some detail in laboratory conditions but mostly exposing wildlife to a single stressor, while the consequences of combined exposure to contaminants and other stressor remain mostly unexplored. We exposed 228 adult zebrafish to a sublethal dose of methylmercury (MeHg), a globally distributed contaminant, and food restriction, probably the most common environmental stressor, in four treatment groups: control, MeHg (5 ppm through diet), food reduction (25 % of control food mass) and the combination of MeHg and food reduction. Our hypothesis was that combined exposure will produce synergistic (interactive) effects different and more severe than the mere addition of the individual effects. We exposed fish for 43-day sublethal exposure, and allowed them three reproductive attempts, whose success we measured using seven reproductive endpoints. We assessed each endpoint with five competitive models: No effect; MeHg effect; food restriction effect; MeHg and food restriction additive effect; and MeHg and food restriction interactive effect. In six of the seven endpoints the evidence contained in the results supported the interactive effect, strongly supporting our hypothesis. In the remaining one, no effects was observed in any group. However, contrary to our expectation, the combined exposure treatment group produced more viable offspring than any other. We currently have no explanation for that result and argue that combined exposure might have triggered life history trade-offs. Further research on the longer term and assessing carry-over and inter-generational effects could improve our understanding of the consequences of combined exposure to MeHg and food restriction.

The residual antibiotics in aquatic animals present potential risk to ecological environment and food safety. Here, we uncover the biochemical reaction and molecular mechanisms in marine medaka embryos exposed to semicarbazide (SEM) at environmental relevant concentrations (10, 50 and 100 μg/L) for 14 days then followed by 7 days clean water recovery period. The decreased levels total superoxide dismutase (T-SOD) and catalase (CAT), and increased levels in malondialdehyde (MDA) content suggesting SEM induced severe oxidative stress and excessive reactive oxygen species (ROS). These effects further contributed to morphological changes and cardiac dysfunction. Meanwhile, oxidative stress activated genes associated with inflammatory responses (tlr1, cyp1a1, ahr, il-1β), implying potential suppression of innate immune functions. Furthermore, elevated activities of pyruvate kinase (PK), hexokinase (HK), and lactate dehydrogenase (LDH), along with decreased succinate dehydrogenase (SDH) activity, indicated SEM activate glycolysis pathway and disrupt Tricarboxylic Acid cycle (TCA) cycle leading to mitochondrial function and energy metabolism imbalance. Notably, these adverse effects cannot be completely eliminated after the short recovery period, implying a potential long-term toxicity of SEM. This study provides new insights into the toxicity effect SEM on the early developmental of marine organisms, its underlying regulatory mechanisms and implications for SEM risk management.

The increasing prevalence of harmful algal blooms (HABs), specifically those resulted by toxigenic Alexandrium spp., notably threats human health and aquatic ecosystem. Metal organic frameworks (MOFs), particularly copper- and zinc-based MOFs have emerged as promising materials to control HABs. However, their application safety needs to be assessed because of poor knowledge of their ecotoxicity to marine organisms. In this study, the toxicity of Cu-MOF and Zn-MOF was evaluated to Oryzias melastigma at embryonic and adult stages. The Cu-MOF exhibited a concentration-dependent mortality and hatching rate at concentrations ≥ 2.0 mg L^-1. The Zn-MOF exhibited similar effects when the exposure doses ≥ 80 mg L^-1. Additionally, adult fish after exposure to Cu-MOF showed significant mortality rate at higher concentrations (≥ 4.0 mg L^-1), beside elevated oxidative stress markers. In contrast, Zn-MOF did not show mortality and oxidative stress although bioaccumulation of Zn²⁺ occurred in tissues. Based on the safety assessment of MOFs to marine medaka, the dosages for application of Cu-MOF (≤ 1.0 mg L^-1) and Zn-MOF (≤ 20 mg L^-1) are safe for controlling A. minutum-forming HABs. This study hints that the application of MOFs in mitigation of HABs should be carefully evaluated to balance their benefits in contrast to ecological risks.

Per-and polyfluoroalkyl substances (PFAS) are ubiquitous contaminants in freshwater ecosystems. Many PFAS are incorporated into food webs, with potential effects on ecological and human health. However, PFAS incorporation into the base of aquatic food webs remains poorly understood. The goal of this study was to quantify the uptake and trophic transfer of both legacy PFAS and the perfluoroether acid Nafion byproduct 2 (NBP2) using a simulated freshwater food chain in a lab setting. Natural periphytic biofilms were placed into trays containing equimolar binary aqueous PFAS mixtures at environmentally relevant concentrations for five days. Following the initial exposure period, newly hatched mayfly larvae were introduced into each tray to feed on periphyton for most of their larval development. The mature larvae were then fed to zebrafish. All water and biota samples contained detectable levels of the tested PFAS. All PFAS were more concentrated in periphyton than in water, and four of six PFAS were further concentrated in mayfly larvae relative to periphyton. PFDA was the most accumulative in all biota. PFAS concentrations in zebrafish were significantly correlated with those in larval mayflies. Assimilation efficiencies in zebrafish were high (>70 %) for all compounds. Bioaccumulation of PFAS in periphyton and mayflies was positively correlated with log K_OW and number of carbons. Our findings demonstrate the functionality of the periphyton-mayfly-zebrafish food chain for studying the trophic transfer of PFAS, and provide novel data showing that the bioaccumulation of NBP2 is comparable to legacy PFAS.

The Baltic Sea's limited water exchange and densely populated catchment area contribute to the frequent co-occurrence of hypoxia and chemical pollutants such as copper (Cu), raising concerns about the effects of sequential stressors on marine organisms. This study tested whether pre-exposure to intermittent oxygen stress alters the physiological and immune responses of Mytilus edulis to subsequent Cu exposure. Mussels were preconditioned for 21 days to either mild intermittent hypoxia (7 h/day at ∼2 mg/L DO) or severe intermittent anoxia (2 days/week at <0.01 mg/L DO), followed by a 7-day exposure to sublethal Cu (20 µg/L) under normoxia. Hypoxia preconditioning impaired Cu homeostasis, leading to elevated Cu accumulation. Hypoxia-exposed mussels maintained immune function (phagocytosis, lysosomal integrity, acid phosphatase activity), while anoxia disrupted phagocyte-lysosome balance. Cu exposure alone reduced hemocyte abundance and increased acid phosphatase activity, indicating typical immunotoxic effects that were not alleviated by prior oxygen stress. Lipid reserves declined under both oxygen regimes, while carbohydrate and protein levels were reduced by hypoxia. Anoxia preconditioning mitigated Cu-induced energy depletion, as reflected by elevated lipid and carbohydrate levels. Mitochondrial electron transport system activity increased following low oxygen preconditioning and further during Cu exposure, suggesting elevated energy demands at post-stress recovery/detoxification. Despite these bioenergetic adjustments, oxidative stress markers (total antioxidant capacity, lipid peroxidation) and stress gene expression (hsp70, hsp90, GADD45A, nrf2, NfκB) remained stable across treatments. In conclusion, while oxygen stress modulated mussel responses to Cu, it did not confer cross-tolerance, highlighting the complex and context-dependent nature of multiple stressor interactions in coastal environments.

Environmental pollutants, particularly endocrine disruptors, are known to significantly dysregulate lipid homeostasis, causing severe health issues. However, their obesogenic effects on invertebrate species, such as the planktonic crustacean Daphnia magna, remain poorly understood. Previous research suggested that compounds such as organotin tributyltin and the insecticide pyriproxyfen promote lipid accumulation, particularly triacylglycerol species. However, bulk LC-MS methodologies used did not retain the spatial context of the biomolecules analyzed, failing in providing crucial insights into the tissue-specific molecular effects of pollutant exposure and risk assessment. The present study evaluates the disruptive effects of these compounds at the lipidomic level using a novel spatial MALDI-MSI-based approach integrated with ion mobility. In terms of toxicological assessment, MALDI-MSI revealed distinct lipidomic disruptions. Both pollutants increased glycerolipids, but glycerophospholipids exhibited opposing patterns. Tributyltin significantly altered the lipid composition of the nervous system, whereas pyriproxyfen predominantly affected the cardiovascular system. In conclusion, the integration of MALDI-MSI with ion mobility not only enhanced the identification of lipids but also allowed to provide deeper insights into the tissue-specific toxicological mechanisms of environmental obesogens in Daphnia magna. Additionally, this study emphasizes the potential of these state-of-the-art analytical techniques in advancing spatial biology and environmental risk assessment.

The widespread use of antibiotics in aquaculture has led to significant concerns regarding their presence in aquatic environments, their bioaccumulation in fish, and their potential toxicity to both aquatic life and human consumers. Antibiotics are extensively utilized to prevent and treat bacterial infections in farmed fish, but their residues have been detected in fish tissues, water bodies, and sediments. These residues contribute to antibiotic resistance, disrupt microbial ecosystems, and pose health risks upon consumption. The bioaccumulation and bioconcentration of antibiotic residues in fish tissues vary depending on the type of antibiotic, species of fish, and environmental factors. Advanced detection techniques, including high-performance liquid chromatography (HPLC) and mass spectrometry (MS), have been instrumental in identifying antibiotic residues with high precision. However, cost-effective alternatives such as the enzyme-linked immunosorbent assay (ELISA) have also been explored for routine monitoring. The toxicity of antibiotic residues in fish has been associated with physiological alterations, immunosuppression, and reduced reproductive capacity, highlighting the necessity for stringent regulations and monitoring mechanisms. Regulatory frameworks such as the maximum residue limits (MRLs) established by the European Union and national guidelines aim to control antibiotic residues in fishery products. Despite these efforts, the persistence of antibiotics in aquatic environments calls for the promotion of alternative disease management strategies, such as probiotics and immunostimulants, to reduce antibiotic dependency. This review provides a comprehensive analysis of antibiotic accessibility, detection methods, bioaccumulation, bioconcentration, and toxicity in fish. These findings underscore the need for enhanced regulatory measures, sustainable aquaculture practices, and continued research on the long-term ecological and health implications of antibiotic residues in aquatic environments.