Daphnia magna model in the toxicity assessment of pharmaceuticals: A review

The chronic effects of polyethylene terephthalate and biodegradable polyhydroxybutyrate microplastics on Daphniamagna

The inappropriate disposal of plastic materials and their slow decomposition into microplastics (MP) pollutes aquatic ecosystems, leading to toxic effects on organisms. MP can have different shapes and be made from different polymeric materials; being carbon-based polymers the common ones. The toxicity associated with such MP has led to the need to search for alternative polymers with faster degradation times. Biodegradable polymers such as polyhydroxybutyrate (PHB) are promising substitutes for synthetic polymers. In this work, the environmental impact of PHB was determined and compared to that of polyethylene terephthalate (PET). For this purpose, the model organism Daphnia magna was used in a 26-day experiment. The toxic effects of MPs was assessed by analysing the survival, the swimming velocity and the filtration rate of Daphnia magna. After 21 days of exposure, PET in the form of fibers or fragments caused the most toxicity, resulting in a 20% decrease in swimming velocity and a 20% of Daphnia magna survival. However, after 21 days, PHB resulted in 80% survival, which is comparable to control experiments, and Daphnia magna showed mobility that was comparable to that seen for control experiments. Therefore, with the presence of food PHB microplastic particles had no negative effects on Daphnia magna. Considering these results, PHB might be a promising material as a substitute of conventional polymers.

Quantitative approach for assessing risks and benefits to the supply of ecosystem services in response to human activities

Escalating human activities threaten ecosystems and the benefits they provide, known as ecosystem services (ES). Despite the recognized importance of ES for both ecological health and human well-being, integrated methods for evaluating ES within decision-making frameworks remain limited. Current environmental assessments, such as ecological risk assessment (ERA), typically focus on risks to specific endpoints such as survival, growth and reproduction of test species without capturing broader ecosystem risks and benefits. This study introduces a novel method designed to quantitatively assess risks and benefits to ES supply by integrating ES as assessment endpoints within ERA. Using cumulative distribution functions, we establish risk and benefit thresholds and calculate the probability and magnitude of exceeding these following human interventions. The method was tested by quantifying risk and benefit metrics for a regulating ES, waste remediation, in three marine offshore case studies: an existing offshore wind farm, a hypothetical mussel longline culture, and a multi-use scenario combining both. The results enabled detailed comparisons of the probability and magnitude of creating risks and providing benefits across scenarios, demonstrating the utility of cumulative distribution functions for both visualizing and quantifying risks and benefits to ES supply. This generic and broadly applicable method can evaluate ES trade-offs regardless of the ecosystem under study, providing a valuable tool to operationalize the integration of ES into decision-making and environmental management frameworks.

Impact of black phosphorus nanosheet exposure on growth, reproduction, antioxidant mechanisms, and transcriptomic responses in Daphnia magna

Black phosphorus nanosheets (BPNS), a novel two-dimensional nanomaterial, have garnered significant attention in biomedical and technological applications due to their exceptional physicochemical properties. However, their widespread use raises concerns about potential environmental risks. In this study, we elucidate the toxicological mechanisms of BPNS on Daphnia magna (D. magna), a model aquatic organism. The results reveal that BPNS is efficiently absorbed and accumulates in the intestinal tract of D. magna. Exposure to low concentrations of BPNS significantly alters developmental and reproductive performance, as evidenced by a 2-day acceleration in the time to first brood and an increase in body length from 3.1 to 3.3 mm. Furthermore, BPNS exposure induces oxidative stress in D. magna, characterized by elevated reactive oxygen species (ROS) levels, enhanced activities of superoxide dismutase (SOD) and catalase (CAT), and increased malondialdehyde (MDA) concentrations. RNA sequencing analysis indicates that dysregulation of iron homeostasis plays a pivotal role in mediating oxidative stress in D. magna. Concurrently, detoxification mechanisms are activated, as evidenced by upregulation of genes associated with chitin and carbohydrate metabolism, as well as cuticle structure components. Additionally, BPNS exposure modulates key signaling pathways, including the lysosomal pathway, starch and sucrose metabolism, and steroid biosynthesis, which collectively enhance the stress tolerance of D. magna. These findings provide critical insights into the ecological implications of BPNS release into aquatic ecosystems, highlighting the need for comprehensive risk assessments of emerging nanomaterials.

Chronic Broadband Noise Increases the Fitness of a Laboratory-Raised Freshwater Zooplankton

Although there is an increasing interest in the effects of anthropogenic noise on underwater wildlife, most studies focus on marine mammals and fish, while many other taxa of substantial ecological importance are still overlooked. This is the case for zooplankton species, which ensure the coupling between primary producers and fishes in pelagic food webs. Here, we measured lifespan, reproduction, and mobility of laboratory-raised water fleas Daphnia magna, a widespread freshwater zooplankton species, in response to continuous broadband noise. Surprisingly, we found a significant increase in survival and fecundity, leading to a higher individual fitness when considering total offspring production and a slight increase in the population growth rate according to the Euler-Lotka equation. Exposed water fleas were found to be slower than control individuals, and we discussed potential links between mobility and fitness. Our results can have implications in aquaculture and for in-lab studies (e.g., in ecotoxicology) where the acoustic environment receives little attention. Chronic broadband noise can be associated with certain human activities, but the consequences for natural Daphnia populations might differ as reduced velocity could have negative outcomes when considering competition and predation. Our work is one of the few showing an effect of noise on individual fitness and suggests that noise should be better accounted for in laboratory studies.

Toxicity Assessment of Catechins on Representative Aquatic Organisms and Terrestrial Plant

Catechins, renowned for their health benefits, have unexamined environmental impacts. This study assessed the toxicity of crude catechin and catechin hydrate on invertebrate larvae, plant, and microalgae. The survival rates of Daphnia magna Straus and Artemia salina L. were monitored every 24 h over a three-day period. The germination rate and radicle length of Lactuca sativa L. was measured every 24 h for four days. Inhibitory effects were evaluated in both freshwater and seawater cultures of Chlorella vulgaris Beijerinck, with cell density recorded every 24 h and yield inhibition calculated after 96 h. Results indicated that increasing catechin concentration and exposure duration decreased the survival rate of D. magna and A. salina. Daphnia magna was more sensitive to catechins than A. salina, with 24 h lethal concentration 50 (LC-50) values of 1174 µg/mL compared to 1895 µg/mL for crude catechin, and 54 µg/mL compared to 153 µg/mL for catechin hydrate. The germination rate and radicle length of L. sativa, along with the cell density of C. vulgaris, decreased with increasing catechin concentration, but remained higher even after prolonged exposure. At low catechin concentrations, C. vulgaris cell density exceeded control levels. This study demonstrates that catechins in aquatic environments can significantly impact ecosystems. At certain concentrations, catechins are toxic and potentially lethal to aquatic organisms. Conversely, at lower concentrations, catechins may promote microalgal growth, suggesting a fertilizing effect. Understanding these dynamics is crucial for maintaining the stability of aquatic ecosystems.

Effects of microplastics and natural particles on the aquatic invertebrate Daphnia magna under different dietary quality scenarios

Natural and synthetic particles co-occur in the aquatic environment. However, little information is available about the effects of natural particles on freshwater animals and how these effects differ from those of synthetic particles, especially under the scenarios of decreasing dietary quality and increasing cyanobacteria in the aquatic environment. Therefore, this study evaluated apical and molecular effects of polypropylene (PP) microplastics (MPs) and three natural non-food particles (i.e., kaolin, peat, and sediment) on the freshwater invertebrate Daphnia magna fed either a green alga or a mixture of green alga and cyanobacterium. After the 21-d chronic exposure of 10 mg/L PP when using the green alga Acutodesmus sp. as diet, the size of D. magna was significantly reduced, and the molting time was significantly extended compared with the control. However, the chronic effects of PP were masked when the cyanobacterium Pseudanabaena sp. was added to their diet. The natural particles kaolin, peat, and sediment posed insignificant effects on D. magna regardless of dietary quality. The expression of molting-related genes (e.g., ecr-a) and oxidative stress-related genes (e.g., sod2) was significantly upregulated in D. magna with the exposure of both natural and synthetic particles. The predicted no-effect concentration of PP was derived as 0.025 mg/L, raising concerns relating to their toxicity and risks in the contaminated aquatic environment. This study will improve our understanding of the effects and risks of natural and synthetic particles in freshwater environments, as well as facilitate ecoenvironmental authorities to make informed decisions on the appropriate management of MPs.

Lithium with environmentally relevant concentrations interferes with mitochondrial function, antioxidant response, and autophagy processes in Daphnia magna, leading to changes in life-history traits and behavior

With the increasing production and use of lithium-based products, concerns over lithium pollution in aquatic ecosystems are increasing, whereas research on its toxicity mechanisms in aquatic organisms remains limited. The main objective of the present study was to explore the effects of environmentally relevant concentrations of lithium exposure on the life-history strategy, behavior, antioxidant system, and autophagy process of Daphnia magna. Acute (24-96 h) and chronic (21 days) exposure experiments under three lithium treatments (low: 8.34 μg/L, medium: 83.44 μg/L, and high: 834.41 μg/L) were conducted. The results indicated that exposure to medium and high lithium concentrations led to eye and tail deformities in D. magna. Furthermore, developmental and reproductive parameters such as body length, total neonates per female, and average neonates per time were negatively influenced. Lithium also interfered with energy metabolism to cause the decreasing swimming speed and the reduction in the swimming range. In addition, lithium exposure affected the expression of gsk-3β, further disrupting the dynamic balance of mitochondrial fission, fusion, and regeneration, which caused ROS accumulation and induced oxidative stress. D. magna attenuated the stress by activating the FoxO/SESN and Nrf2/Keap1 pathways, synergistically enhancing downstream antioxidant enzymes expression. Concurrently, D. magna also mitigated oxidative stress and mitochondrial damage by promoting autophagy and inhibiting apoptosis. In summary, lithium harmed the physiological and biochemical functions of D. magna through multiple mechanisms, suggesting that environmental lithium pollution may pose a potential threat to aquatic organisms.

Aquatic toxicity of leachates from crystalline silicon photovoltaic components

Previous ecotoxicological assessments of solar photovoltaic (PV) technologies vary considerably and focus solely on the active cell layer. A comprehensive evaluation of all possible sources of toxicity is required for proper disposal classification of waste materials. We evaluated the aquatic ecotoxicity of separated PV components from three crystalline silicon modules to crustacea, Daphnia magna. Modules were separated into three categories for testing: 1) powdered glass and cell, 2) encapsulation and back sheet polymers, and 3) junction box and cables. Batch leachates were used in bioassays and assessed for metal and microplastic leaching. The powder and polymers from two tested modules had little observed impact on daphnids, while the third showed significant toxicity with EC50s at 5% or less leachate. One junction box and cable mixture had significant toxicity with an EC50 of less than 10%. Upon metal analysis, Al and Ag leached in high concentrations upon metal analysis and were the primary suspects for ecotoxicological effects. Microplastics were not detected in powder or encapsulation and back sheet leachates, while there was evidence of hydrocarbon polymers in junction box and cable leachates. This work confirmed that metals in the active layer of solar modules are a primary source of concern, and potential microplastic leaching from junction boxes and cables should not be overlooked. Overall, the acute toxicity of silicon solar photovoltaics depends on the module type, components considered, and leachate exposure concentrations.

ADME, Toxicity, Molecular Docking, Molecular Dynamics, Glucokinase activation, DPP-IV, α-amylase, and α-glucosidase Inhibition Assays of Mangiferin and Friedelin for Antidiabetic Potential

Today the alarming situation of diabetes seeks innovative antidiabetic medications, especially those derived from natural sources, as natural substances are safer than manufactured pharmaceuticals. Therefore, this study investigated the inhibitory properties of mangiferin and friedelin against glucokinase (GK), dipeptidyl peptidase-IV (DPP-IV), α-amylase, and α-glucosidase using computational methods, in vitro enzyme assays, and in-depth ADMET analysis. The study utilized a computer-aided drug design approach to assess the potential therapeutic properties of mangiferin and friedelin as Type 2 diabetes mellitus (T2DM) therapeutic agents. Molecular docking studies' outcomes encouraged the evaluation of both compounds in in vitro enzymatic assays. The docking study results were validated with the help of molecular dynamics simulation. Mangiferin and friedelin showed that they activated GK 20% and 5% more than the basal activity of the enzyme, respectively. In the DPP-IV enzyme assay, mangiferin and friedelin demonstrated IC50 values (74.93 ± 0.71 and 110.64 ± 0.21 µg/mL, respectively) comparable with the reference compound sitagliptin. Moreover, mangiferin and friedelin showed IC50 comparable to acarbose against α-amylase (9.72 ± 0.15, 11.84 ± 0.06, and 10.19 ± 0.05 mg/mL, respectively). In the α-glucosidase enzyme assay, mangiferin, friedelin, and acarbose displayed 11.72 ± 0.10, 14.34 ± 0.02, and 9.14 ± 0.06 mg/mL of IC50 values, respectively. The compounds showed promising in silico ADMET and drug-likeness properties, with potential binding affinities with all enzymes. In vitro enzymatic assays showed mangiferin and friedelin activated GK 20% and 5% more than basal activity, with IC50 values comparable to acarbose.

Weak salinization alleviates the harmful impact of cyanobacteria on water fleas

Climate change and anthropogenic activities are driving dramatic changes in aquatic ecosystems. In this context, cyanobacterial blooms and freshwater salinization have recently received much attention, however, the comprehensive effects of these stressors on aquatic organisms are complex and have yet to be accurately clarified. This study tested the harmful effects of cyanobacteria and increasing salinity on zooplankton by characterizing the life-history traits and gut microbiota composition in the large-bodied Daphnia pulex and small-bodied Simocephalus vetulus. In 0 g L-1 salinity, the intrinsic growth rates of both species decreased when fed a diet containing cyanobacteria. Without cyanobacteria, the intrinsic growth rate of D. pulex was highest at 1 g L-1 salinity and lowest at 2 g L-1, whereas that of S. vetulus declined as salinity levels rose. Salinity alleviated the negative effects of cyanobacteria on water fleas. D. pulex performed worse than S. vetulus under high salinity (2 g L-1), cyanobacteria or their combined effects. Salinity changed the dominant gut microbiota in the water fleas when fed cyanobacteria. Bacteroides sp. and Cetobacterium sp. in D. pulex and Cetobacterium sp. in S. vetulus were most abundant when the water fleas were reared at low salinity (1 g L-1). The consistent changes in the dominant bacterial groups and the life-history traits indicate that the gut microbiota might adjust their tolerance to cyanobacteria.

Promising Prodiginins Biological Activities

Prodiginins are a large family of at least 34 pyrrolic compounds, including the well-studied red pigment prodigiosin. Prodiginins are produced by several microorganisms displaying broad biological activities, including antimicrobial, antiviral, antiparasitic, antiproliferative, and immunosuppressive activities. The present review aims to compile and analyze the main physicochemical and biological properties and mechanisms of action of prodiginins for microbial disease treatment, particularly SARS-CoV-2 disease and opportunistic infections related to COVID-19. The interaction of prodigiosin, as a model molecule, with cellular membranes, potential drug delivery devices, and toxicological studies, and in silico studies using molecular dynamics showed that the prodigiosin motif, which interacts with lipids, opens a new door for the potential therapeutic use of prodiginins.

The role of pyruvate dehydrogenase in the lifespan determination of daphnids

The general association between longevity and energy metabolism has been well-documented for some time, yet the specific metabolic processes that regulate longevity remain largely unexplored. In contrast to the common active swimming daphnids (e.g., Daphnia sinensis), Simocephalus vetulus is notable for being sedentary and having a lower metabolic rate, yet it has a longer lifespan than D. sinensis. In this study, metabolomic analysis and drug validation experiments are employed to demonstrate that the lower pyruvate dehydrogenase (PDH) activity reduces the locomotor performance of S. vetulus and to identify PDH activity as a regulator of the lifespan of daphnids. Inhibition of PDH activity in daphnids by CPI-613 attenuates its ATP supply and locomotor performance but significantly induces longevity. The study also determines that the invertebrate neurotransmitter octopamine and temperature have a significant impact on PDH activity and modulate daphnids lifespan. And when the effects of temperature and octopamine on PDH activity are counteracted by inhibitors or agonists, the impact on lifespan becomes ineffective. These results support an important role for PDH in lifespan regulation and locomotor performance in daphnids and provide insights into the metabolic regulation of lifespan.

Genome-wide DNA methylation patterns in Daphnia magna are not significantly associated with age

BACKGROUND

DNA methylation plays a crucial role in gene regulation and epigenetic inheritance across diverse organisms. Daphnia magna, a model organism in ecological and evolutionary research, has been widely used to study environmental responses, pharmaceutical toxicity, and developmental plasticity. However, its DNA methylation landscape and age-related epigenetic changes remain incompletely understood.

RESULTS

In this study, we characterized DNA methyltransferases (DNMTs) and mapped DNA methylation across the D. magna genome using whole-genome bisulfite sequencing. Our analysis identified three DNMTs: a highly expressed but nonfunctional de novo methyltransferase (DNMT3.1), alongside lowly expressed yet functional de novo methyltransferase (DNMT3.2) and maintenance methyltransferase (DNMT1). D. magna exhibits overall low DNA methylation, targeting primarily CpG dinucleotides. Methylation is sparse at promoters but elevated in the first exons downstream of transcription start sites, with these exons showing hypermethylation relative to adjacent introns. To examine age-associated DNA methylation changes, we analyzed D. magna individuals across multiple life stages. Our results showed no significant global differences in DNA methylation levels between young, mature, and old individuals, nor any age-related clustering in dimensionality reduction analyses. Attempts to construct an epigenetic clock using machine learning models did not yield accurate age predictions, likely due to the overall low DNA methylation levels and lack of robust age-associated methylation changes.

CONCLUSIONS

This study provides a comprehensive characterization of D. magna's DNA methylation landscape and DNMT enzymes, highlighting a distinct pattern of exon-biased CpG methylation. Contrary to prior studies, we found no strong evidence supporting age-associated epigenetic changes, suggesting that DNA methylation may have a limited role in aging in D. magna. These findings enhance our understanding of invertebrate epigenetics and emphasize the need for further research into the interplay between DNA methylation, environmental factors, and gene regulation in D. magna.

Assessing the toxicity of gadolinium in freshwater and marine ecosystems: Effects across trophic levels

Rare Earth Elements, particularly gadolinium (Gd), are increasingly used in industrial and medical applications, leading to their dispersion in aquatic environments. This study examines the ecotoxicological effects of Gd on aquatic organisms across different trophic levels in freshwater and marine ecosystems. Using standardized bioassays, the impact of Gd was assessed on Aliivibrio fischeri, Raphidocelis subcapitata, Phaeodactylum tricornutum, Daphnia magna, and Paracentrotus lividus larvae. Results showed that primary producers exhibited the highest sensitivity, with growth inhibition at low concentrations. In contrast, primary consumers (D. magna and P. lividus) were less affected by Gd, displaying a higher tolerance to its toxic effects even at elevated concentrations. Principal component analysis highlighted distinct responses between freshwater and marine organisms, suggesting a complex relationship between Gd bioavailability and toxicity. Hence, Gd contamination poses ecological risks requiring further research on its environmental impact.

Development of a bioreactor with an integrated non-dispersive infrared CO2 sensor for rapid and sensitive detection of Cr(VI) toxicity in water

Whole-cell bioreactors equipped with external physico-chemical sensors have gained attention for real-time toxicity monitoring. However, deploying these systems in practice is challenging due to potential interference from unknown wastewater constituents with liquid-contacted sensors. In this study, a novel approach using a bioreactor integrated with a non-dispersive infrared CO₂ sensor for both toxicity detection and real-time monitoring of microbial growth phases was successfully demonstrated. Online detection of microbial-generated CO2 in gas-phase which is considered as a non-invasive method could significantly improve real-time monitoring of microbial growth phases while addressing some of the aforementioned limitations of conventional whole-cell toxicity biosensors. Pseudomonas koreensis ICTTOX1, which was isolated from wastewater and identified using MALDI-TOF mass spectrometry and 16S rRNA sequencing, was employed as the microbial source for Cr(VI) toxicity testing. Using the cells selected in the early-log phase, where its protective mechanisms have not yet fully activated, and conducting parallel toxic and blank runs contribute to the promising limit of detection, sensitivity, and reproducibility of the method. By achieving an IC₅₀ of 0.16 mg/L for Cr(VI), this method demonstrates significantly higher sensitivity compared to other reported toxicity assays. Moreover, the sensitivity of the early-log cells was maintained for 24 h of storage at 10°C. A statistically significant difference between the blank sample and 0.01 mg/L Cr(VI) solution confirms the ability of the method to detect Cr(VI) toxicity at the limited value of surface water quality in Vietnam. The largest coefficient of variation of inhibition was found to be 12 %, aligning with the recommended value for the validation of bioanalytical methods according to USFDA. These findings support the development of an eco-friendly and sensitive method for rapid detection of Cr(VI) toxicity, enabling early warning of pollution events to enhance environmental safety. However, the study is limited by the absence of chromium speciation analysis during microbial metabolism, which should be explored in future research.

Chronic toxicity and intergenerational effects of N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine (6PPD) exposure alone and in combination with Zn2+ on Daphnia magna (Cladocera)

N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine (6PPD) and Zn2+, extensively used in the tire manufacturing process, are frequently detected in freshwater environments. However, the intergenerational effects of isolated 6PPD exposure and joint 6PPD and Zn2+ exposure at concentrations approximating environmental levels remain unknown. This study assessed the chronic toxicity and intergenerational effects of 6PPD (0.02-20 μg/L) and a mixture of 6PPD and Zn2+ (5 μg/L) over three generations in Daphnia magna bioassays. In the F0 generation, a dose-dependent decline in total offspring number was observed with 6PPD exposure alone, while co-exposure with Zn2+ exacerbated the reproductive toxicity of 6PPD. Across three generations, low-dose (0.02 µg/L) 6PPD alone and combined with Zn2+ induced a cumulative degenerative maternal effect. Conversely, high-dose (20 µg/L) 6PPD, both independently and in combination with Zn2+, exhibited an adaptive maternal effect. Notably, the grandmaternal effect emerged exclusively in the co-exposure group treated with 20 μg/L 6PPD and 5 μg/L Zn2+, with no such effect in the group exposed to 20 μg/L 6PPD alone, suggesting that Zn2+ may enhance the potential toxicity of 6PPD. Overall, this study provides novel insight into the intergenerational impacts of environmentally relevant levels of 6PPD alone and in combination with a heavy metal, elucidating the environmental risks posed by tire-derived chemicals through their synergistic effects on transgenerational toxicity.

Juvenile apple snails as new biomonitors of freshwater pollution: Insight into copper and lead toxicity and underlying molecular mechanisms

Environmental pollutants, such as heavy metals, pose significant threats to organisms across different trophic levels in the aquatic environment. Although the effects of heavy metals have been extensively studied in a limited number of model organisms, their toxicity and underlying mechanisms remain poorly understood in numerous aquatic invertebrates. Here, we underscore the potential of the apple snail Pomacea canaliculata as an environmental bioindicator for freshwater heavy metal pollution, advancing biomonitoring methodologies. By integrating physiological, enzymatic, transcriptomic, and proteomic analyses, we conducted a thorough evaluation of the toxic effects and mechanisms of copper (Cu) and lead (Pb) on juvenile snails. Our results demonstrated that juvenile P. canaliculata was more sensitive to Cu and Pb compared with other aquatic invertebrates with heart rate drop serving as a reliable indicator of metal exposure. Antioxidant enzyme activity exhibited a distinct response, increasing at low Pb concentrations but decreasing at high concentrations, while Cu suppressed the activity even at a low concentration. At the molecular level, a total of 467 and 267 differentially expressed genes and 629 and 204 differentially expressed proteins were identified in the juveniles exposed to sublethal concentrations of Cu (40 μg/L) and Pb (1500 μg/L) for 72 h, respectively. Functional analysis further revealed distinct molecular toxicity in P. canaliculata. Under Pb exposure, key pathways related to cellular oxidant detoxification, transmembrane transporter activity, and ATP hydrolysis activity were enriched, while Cu significantly activated chitin binding, oxidoreductase activity and extracellular region. Overall, our findings highlight the exceptional capacity of P. canaliculata juveniles to differentiate the toxicity and molecular toxic mechanisms of heavy metals, establishing this species as an important and sensitive biomonitor for accurately assessing freshwater heavy metal pollution. This advancement enhances our understanding of ecological health and offers valuable tools for policymakers and conservationists to address the impacts of environmental contaminants.

Predicting acute toxicity of pesticides towards Daphnia magna with random forest algorithm

A large number of pesticides are released into the environment, resulting in serious threat for aquatic organisms. In this work, 15 quantum chemical descriptors were used to develop a quantitative structure-activity/toxicity relationship (QSAR/QSTR) model for toxicity pEC50 of 745 pesticides towards Daphnia magna, by using random forest algorithm. The optimal QSTR model in this paper yielded a coefficient of determination of 0.828, root-mean-square error of 0.798, and mean absolute error of 0.628 for the test set of 149 pesticides, which are accurate values compared with those of QSTR models published recently. Research has revealed that increasing molecular size (or molar volume), the most positive atomic Mulliken (or APT) charge with hydrogens summed into heavy, and the highest occupied molecular orbital (HOMO) energy, can result in higher toxicity pEC50. Increasing the lowest unoccupied molecular orbital (LUMO) energy and the HOMO and LUMO energy gap can lead to lower toxicity pEC50.

Chronic toxicity of tetraconazole and penconazole to Daphnia magna: Insights of growth, reproduction and gene expression changes

Tetraconazole and penconazole are widely used fungicides belonging to the conazole family. Due to the increasing use of these fungicides, their concentrations in aquatic environments are increasing and imply a serious threat to aquatic organisms. However, no studies have investigated the effects of tetraconazole and penconazole on aquatic invertebrates. This study examined for the first time, changes in growth, reproduction, and survival rate as well as changes in the expression of genes related to detoxification (HR96, P-GP, CYP360A8, GST) and reproduction (CUT, CYP314, DMRT, VTG) in D. magna after exposed to different tetraconazole and penconazole concentrations for 21 days. The 48-h EC50 value was 12.35 μg/L for tetraconazole and 326.8 μg/L for penconazole. Chronic toxicity results showed that exposure to varying concentrations of tetraconazole and penconazole decreased body length, total offspring per female, molting frequency, heartbeat rate per minute, and survival rate, and increased day to the first brood in D. magna. The expression of genes related to detoxification and reproduction changed depending on the fungicide type and concentration. In general, transcription of genes related to detoxification was more affected by fungicides. The results revealed that tetraconazole and penconazole caused toxicity in D. magna by inhibiting growth and reproduction and affecting detoxification pathways similarly.

Effects of long-term treatment with low concentration butylparaben on prostate organoids

Endocrine-disrupting compounds (EDCs), such as butylparaben (BP), which are used as preservatives in food and cosmetics, have been shown to negatively affect male reproductive health. Organs under the control of hormones such as androgens and estrogens, such as the prostate, are vulnerable to EDC stimulation. It is well known that BP can cause hormonal imbalances in the prostate and lead to various prostate diseases. However, studies on the long-term exposure of low-dose BP, which is common in daily life, are lacking, and existing studies rely heavily on in vitro tests to assess the risk of EDCs. Therefore, in this study, we investigated the long-term exposure effects of low-dose BP using a prostate organoid model that more closely resembles the target organ. When prostate organoids were treated with BP for a long period, hormonal imbalance was confirmed through differences in the expression of hormone receptors. In addition, reactive oxygen species (ROS) production was confirmed by DCFDA staining, and the protective effect of prostate organoids against stimulation was confirmed by increased protein levels of antioxidant factors. Through transcriptome analysis, we confirmed the occurrence of reproductive toxicity caused by BP. The long-term treatment of prostate organoids with BP causes hormonal imbalance and increased ROS exhibits reproductive toxicity and exerts a protective mechanism against BP through the expression of antioxidant factors. Our results highlight the potential of prostrate organoids as an alternative to animal experimental model and the need for further research on the effects of low EDC concentrations on male reproductive function.

Establishment of a cell culture from Daphnia magna as an in vitro model for (eco)toxicology assays: Case study using Bisphenol A as a representative cytotoxic and endocrine disrupting chemical

Bisphenol A (BPA) is a widely used industrial compound found in polycarbonate plastics, epoxy resin, and various polymer materials, leading to its ubiquitous presence in the environment. The toxicity of BPA to aquatic organisms has been well documented following in vivo exposure scenarios, with known cytotoxic and endocrine-disrupting effects. As such, BPA was used in this study as a well-characterized chemical to implement more ethical and resource-efficient scientific practices in toxicity testing through new approach methods (NAMs). Due to the frequent use of Daphnia spp. as a model organism in toxicology, we developed an in vitro cell culture system from Daphnia magna embryos, with optimized medium to support cell longevity. The cultures were maintained for up to two months, demonstrating their stability and suitability for cytotoxicity studies. Using this novel system, lethal concentration 50 (LC50) values were determined at the 24 and 48 h time points following BPA exposure. Subsequently, oxidative stress, endocrine disruption, and DNA damage were assessed through gene expression, activity assays, and a comet assay in BPA-exposed cells. LC50 values of 52 µM and 20 µM BPA were calculated after 24 and 48 h exposures, respectively. BPA cells exposed to 20 and 52 µM had significantly increased GSH, GPx, and GST activity levels. mRNA expression analysis revealed significant upregulations in the expression of hsp70, hsp90, gst, gpx, vtg1, and cyp4, with downregulations of sod, cat, and ecr following BPA exposure. Furthermore, comet assays showed a significantly higher level of DNA damage induced by BPA compared to controls, with greater comet and tail lengths. This study established a novel in vitro Daphnia model, using BPA as a case study for determining toxic effects, further highlighting the importance and applicability of utilizing alternative methods in ecotoxicological research through reducing animal use.

Assessing the chronic toxicity of climbazole to Daphnia magna: Physiological, biochemical, molecular, and reproductive perspectives

The widespread use of climbazole (CBZ) has led to its increased presence in aquatic environments, potentially threatening freshwater ecosystems. However, evidence regarding the harmful effects of CBZ on aquatic organisms remains limited. In this study, Daphnia magna was exposed to CBZ at concentrations of 0, 0.2, 20, and 200 μg/L for 21 days to evaluate its chronic toxicity through assessment of life-history traits, physiological parameters, biochemical analyses, and gene expression. The results indicated that CBZ exposure delayed the days to the first brood, reduced the frequency of molting per adult, decreased the offspring number at first brood, diminished the body length, and decreased both the total number of broods per female and the total number of offspring per female. Additionally, CBZ inhibited the swimming speed, filtration rate, and ingestion rate. Moreover, CBZ altered the levels of superoxide dismutase (SOD), catalase (CAT), and glutathione (GSH), while increasing malondialdehyde (MDA) levels. Gene expression analysis revealed varied responses in mRNA levels related to metabolic detoxification (cyp360a8, gst, and p-gp), digestive enzymes (α-amylase, α-esterase, and trypsin), energy (ak), oxygen transport (dhb), and reproduction (nvd, cyp314, ecr, vtg, and jhe) following CBZ exposure. These results indicate that the presence of CBZ in aquatic environments can induce toxicity by altering energy acquisition, supply, and metabolism; impairing metabolic detoxification pathways; eliciting oxidative stress; and causing reproductive toxicity in D. magna.

Maternal Daphnia magna exposure to the antidepressant sertraline causes molting disorder, multi-generational reproductive and serotonergic dysfunction

Sertraline, one of the most commonly used antidepressants, has exhibited a progressively escalating trend in usage over the course of the last decades years, which have been exacerbated by the COVID-19 pandemic. Here, this study assessed the transgenerational effects of sertraline on the aquatic microcrustacean Daphnia magna, a parthenogenetic model species. The parental D. magna (G0) were exposed to environmentally relevant concentrations of sertraline (0.1 and 10 μg/L) for 21 days at individual and population level, and observed exposure triggered specific increased fecundity and desynchronized molting. These alterations were partially inherited through three subsequent non-exposed generations (G1, G2, and G3), as evidenced by increased fecundity and disordered molting in G1, reduced fecundity in G2, and reduced body size of G3-offspring. The molt-related genes neverland 1 and hormone receptor 3 were significantly different to the control group simultaneously only in the exposed generation, which may well be responsible for the molting asynchrony. Vitellogenin plays an important role in reproduction, and our results indicate that its abnormal expression persists up to G3, which was highly correlated with the expression of serotonin transporter, the drug target of sertraline. This finding suggested that sertraline possesses a sustained reproductive toxicity and disrupting potential and may be associated with serotonin dysregulation caused by compensatory feedback of serotonin transporter. In combination with male birth and upregulation of doublesex and vitellogenin, sertraline was deemed to trigger a self-defense response of D. magna, known as "abandon-ship" by increasing reproductive inputs. However, no males was found in individual reproduction test in each generation, which may suggest some interaction between sertraline and population density. Our findings emphasize that the toxic effects of sertraline can be transferred to unexposed generations, even with different adverse consequences, implying that future studies need to focus on transgenerational delayed effects and the underlying mechanisms.

Edibility of cultivated green seaweed Ulva intestinalis from Monkhali Beach, Cox's Bazar coast of Bangladesh: bio-toxicity and heavy metal contents

Ulva intestinalis (UI) is widely available edible seaweed and has potential to be introduced as functional food items in Bangladesh. However, potential health hazards of this seaweed with biotoxicity assays and its relation to heavy metal contents were not evaluated previously. With these objectives, toxic effects of UI collected from floating raft culture in Monkhali Beach was evaluated using various organisms such as Chlorella vulgaris, Artemia salina, Daphnia magna, and Lactuca sativa. In relation to this effects, heavy metal concentrations (Fe, Cr, Ni, Cu, Zn, Pb, Cd, and As) and its potential health hazards were subsequently analyzed. The results showed that UI water extract had positive effects on the survivability and growth of the all-test organisms over different time periods, with minimal LC50 values, indicating no toxic to tested organisms. However, increased levels of total dissolved solids and electrical conductivity were observed as extract concentrations increased but considered to be safe below 5 mg kg-1, as compared to control. Moreover, Fe, Cr, Ni, Cu and Zn (43.60, 0.10, 0.44, 0.07, 0.27 and 0.13 mg kg-1 of dry weight, respectively) in UI were found to be low levels compared to previous studies, in addition, Cd and As remained not detected. No significant health risk (HQ < 1) and target carcinogenic risk were found. Therefore, UI could be utilized as functional foods or nutraceuticals for health-conscious consumers of Bangladesh without having potential risks.

Deep learning-assisted detection of psychoactive water pollutants using behavioral profiling of zebrafish embryos

Water pollution poses a significant risk to the environment and human health, necessitating the development of innovative detection methods. In this study, a series of representative psychoactive compounds were selected as model pollutants, and a new approach combining zebrafish embryo behavioral phenotyping with deep learning was used to identify and classify water pollutants. Zebrafish embryos were exposed to 17 psychoactive compounds at environmentally relevant concentrations (1 and 10 μg/L), and their locomotor behavior was recorded at 5 and 6 days post-fertilization (dpf). We constructed six distinct zebrafish locomotor track datasets encompassing various observation times and developmental stages and evaluated multiple deep learning models on these datasets. The results demonstrated that the ResNet101 model performed optimally on the 1-min track dataset at 6 dpf, achieving an accuracy of 65.35 %. Interpretability analyses revealed that the model effectively focused on the relevant locomotor track features for classification. These findings suggest that the integration of zebrafish embryo behavioral analysis with deep learning can serve as an environmentally friendly and economical method for detecting water pollutants. This approach offers a new perspective for water quality monitoring and has the potential to assist existing chemical analytical techniques in detection, thereby advancing environmental toxicology research and water pollution control efforts.

In silico identification and characterization of microRNAs from rotifers, cladocerans, and copepods

MicroRNAs (miRNAs) are short non-coding RNA molecules that regulate post-transcription and influence various biological processes across species. Despite various studies of miRNAs in vertebrates, plants, and other organisms, miRNA data in aquatic invertebrates are insufficient. In this study, we identified miRNAs from four aquatic invertebrate species that are widely used in aquatic toxicology: the rotifer Brachionus koreanus, the water flea Daphnia magna, the cyclopoid copepod Paracyclopina nana, and the harpacticoid copepod Tigriopus japonicus, using next-generation sequencing and in silico analysis. We identified total 188, 41, 47, and 100 miRNAs from each species, and target genes were predicted based on 3'-untranslated region information. Target prediction and functional annotation results provided the biological processes of these miRNAs in various development-related mechanisms, signaling transduction, and metabolism-related pathways. Moreover, the network between the miRNAs and their targets concerning defense-related and antioxidant genes suggests the suitability of miRNAs as biomarkers in ecotoxicological studies.

Toxic effects of acute and chronic atorvastatin exposure on antioxidant systems, autophagy processes, energy metabolism and life history in Daphnia magna

Atorvastatin (ATV) is a representative for hypolipidemic pharmaceuticals and is widely detectable in aquatic environments around the world. However, there are limited studies on the potential effects of ATV on aquatic non-target organisms, especially on aquatic invertebrates. In the present study, the model organism, Daphnia magna was used to investigate the responses of antioxidant system, autophagy process and energy metabolism under the acute exposure of ATV (24 h-96 h), and the changes of physiological parameters of D. magna in response to chronic ATV exposure (21 d) was addressed as well. The results showed that ATV caused oxidative stress in D. magna and elevated activities of antioxidant enzymes (SOD, GST, GPx, and TrxR) at 48 h. However, the progressively increasing oxidative pressure eventually suppressed antioxidant capacities and triggered the transcriptional autophagy process in organism under the regulation of Sestrin as well as its regulated genes (P62, LC3, ATG1, and ATG4B). ATV also altered the expression of DNA methylation related genes. Unlike the clinical response, we found acute ATV exposure led to lipid accumulation in D. magna, affecting energy metabolism. Chronic exposure of higher concentration of ATV (50, 500 μg L-1) adversely affected growth and reproduction parameters of D. magna, caused delayed molting, reduced body length, and decreased number and delayed time of neonates production. Lethal effects were observed in the 5000 μg L-1 of ATV. The present study investigated the toxic effects and mechanisms of acute and chronic ATV exposure on D. magna to provide a scientific basis for evaluating the potential ecological risks of statins on aquatic invertebrates.

Ecotoxicological and metabolomic investigation of chronic exposure of Daphnia magna (Straus, 1820) to yttrium environmental concentrations

In order to estimate the effects on aquatic organisms of long-term exposure to low doses of yttrium (Y) as a potential emerging contaminant, ecotoxicological and metabolomic data were collected on the model organism Daphnia magna, a keystone species in freshwater ecosystems. Following an initial acute toxicity assessment, a 21-day chronic exposure experiment was conducted using a sublethal concentration of 27 μg L⁻¹ of Y, corresponding to the effective concentrations inducing 10 % effect (EC10) value for mortality endpoint and simulating the environmental Y level in aquatic systems. Results from the 21-day two-factor experiment combining microcrustacean survival, growth and reproduction bioassays and targeted gas chromatography-mass spectrometry (GC-MS) metabolomics indicated significant adverse effects of chronic exposure to Y on D. magna. Daphnids exposed to Y exhibited a significantly lower survival at day 21, delayed the maturity stage, including their first breeding, and decreased clutch size. On the side of metabolomics, a clear and general increase over time of both the number and the level of detected metabolites in the hydroalcoholic extracts of the whole organisms was observed. However, emerging from this broad temporal pattern, several bioactive metabolites were identified (e.g., 2,4-di‑tert‑butylphenol, itaconic acid, 3-hydroxybutyric acid, and trehalose) whose levels in extracts are linked to the presence of Y. These results emphasize the necessity of considering low-dose, long-term exposure scenarios in environmental risk assessments of rare earth elements (REEs), which have often been overlooked in favour of higher concentration studies.

Biodiversity-safeguarding threshold for urea-fertilizer application on paddy fields: Protozoa-based toxicity tests

Urea is a widely applied fertilizer to enhance crop yields. Ecological risks associated with the excessive application of urea fertilizer threaten the paddy fields' sustainable agriculture and biodiversity preservation. There are no practical thresholds based on proven data on microbial communities. Protozoa are nitrogen-sensitive organisms. For the first time, this study conducted acute and chronic urea toxicity tests on eight species of organisms. The results indicate that Blepharisma sp. is the most sensitive species to urea exposure and is a suitable indicator for determining the safe threshold of urea. This study estimated the predicted no-effect concentration using species sensitivity distribution curves. Subsequently, it established the threshold for urea application in rice fields based on the fields' area and the surface water's height. The short-term safety threshold for urea in the studied paddy field with black soil is 87.7 mg/L, equivalent to 43.85 kg of urea per hectare for a single nitrogen fertilizer application. The long-term safety threshold is 5.02 mg/L, representing the concentration for re-applicating urea. The biodiversity-safeguarding application threshold provides the basis for developing a urea fertilizer reduction protocol to safeguard the paddy fields' biodiversity.

Reproductive toxicity and molecular responses induced by telmisartan in Daphnia magna at environmentally relevant concentrations

With aging population increasing globally, the use of pharmaceutically active compounds is rising. The cardiovascular drug telmisartan has been widely detected in various environmental compartments, including biota, surface waters, and sewage treatment plant effluents at concentrations ranging from ng/L to μg/L levels. This study evaluated the effects of telmisartan on the microcrustacean Daphnia magna at a wide range of concentrations (0.35, 0.70, 1.40, 500, and 1000 μg/L) and revealed significant ecotoxicological implications of this drug, even at environmentally relevant concentration. Acute exposure to telmisartan (1.40, 500, and 1000 μg/L) resulted in a notable decrease in heart rate, while chronic exposure accelerated the time to the first brood by 3 days and reduced neonate body size. Molecular investigations revealed marked downregulation of vitellogenin genes (Vtg1 and Vtg2). Non-monotonic dose responses were observed for gene expression, early-stage body length, and the total number of offspring produced, while the heart rate and time to the first brood showed clear concentration-dependent responses. These findings highlight the potential risks, notably to reproductive capacity, associated with exposure to telmisartan in environmentally relevant concentration, suggesting the need for further studies on the potential long-term ecological consequences.

Ecotoxicity and Mutagenicity Assessment of Novel Antifungal Agents VT-1161 and T-2307

Antifungal substances are essential for managing fungal infections in humans, animals, and plants, and their usage has significantly increased due to the global rise in fungal infections. However, the extensive application of antifungal agents in pharmaceuticals, personal care products, and agriculture has led to their widespread environmental dissemination through various pathways, such as excretion, improper disposal, and agricultural runoff. Despite advances in wastewater treatment, many antifungal compounds persist in the environment, affecting non-target organisms and contributing to resistance development. This study investigates the environmental impact of two novel antifungal agents, VT-1161 and T-2307, recently introduced as alternatives for treating resistant Candida spp. We assessed their ecotoxicity and mutagenicity using multiple bioassays: immobilization of Daphnia magna, growth inhibition of Raphidocelis subcapitata, luminescence inhibition of Aliivibrio fischeri, and mutagenicity on Salmonella typhimurium strain TA100. Results indicate that both VT-1161 and T-2307 exhibit lower toxicity compared to existing antifungal compounds, with effective concentrations (EC50) causing 50% response ranging from 14.34 to 27.92 mg L-1. Furthermore, both agents were classified as less hazardous based on the Globally Harmonized System of Classification and Labeling of Chemicals. Despite these favorable results, further research is needed to understand their environmental behavior, interactions, and potential resistance development among non-target species. Our findings highlight the importance of comprehensive environmental risk assessments to ensure the sustainable use of new antifungal agents.

Analysis of factors affecting microbial degradation of cyanobacterial toxins based on theoretical calculations

Cyanobacterial toxins are the most common algal toxins, which are highly toxic and can persist in the aquatic environment without easy degradation, posing risks to the ecosystem and human health that cannot be ignored. Although microbiological methods for the removal of cyanobacterial toxins from aqueous environments are highly efficient, their degradation efficiency is susceptible to many abiotic environmental factors. In this paper, Microcystin-LR (MC-LR) and its microbial degrading enzymes were selected to study the effects of common environmental factors (temperature (T), NO3-, NH4+, Cu2+, Zn2+) and their levels during microbial degradation of cyanobacterial toxins in aqueous environments by using molecular docking, molecular dynamics simulation, analytical factor design, and the combined toxicokinetics of TOPKAT (toxicity prediction). It was found that the addition of T, NO3- and Cu2+ to the aqueous environment promoted the microbial degradation of MC-LR, while the addition of NH4+ and Zn2+ inhibited the degradation; The level effect study showed that the microbial degradation of MC-LR was promoted by increasing levels of added T and NO3- in the aqueous environment, whereas it was inhibited and then promoted by increasing levels of NH4+, Cu2+ and Zn2+. In addition, the predicted toxicity of common Microcystins (MCs) showed that MC-LR, Microcystin-RR (MC-RR) and Microcystin-YR (MC-YR) were not carcinogenic, developmentally toxic, mutagenic or ocular irritants in humans. MC-LR and MC-RR are mild skin irritants and MC-YR is not a skin irritant. MC-YR has a higher chronic and acute toxicity in humans than MC-LR and MC-RR. Acute/chronic toxicity intensity for aquatic animals: MC-YR > MC-LR > MC-RR and for aquatic plants: MC-LR > MC-YR > MC-RR. This suggests that MC-YR also has a high environmental health risk. This paper provides theoretical support for optimizing the environmental conditions for microbial degradation of cyanobacterial toxins by studying the effects of common environmental factors and their level effects in the aquatic environment.

Local thermal adaption mediates the sensitivity of Daphnia magna to nanoplastics under global warming scenarios

The toxicity of nanoplastics at environmentally relevant concentrations has received widespread attention in the context of global warming. Despite numerous studies on the impact of mean temperature (MT), the effects of daily temperature fluctuations (DTFs) on the ecotoxicity of nanoplastics remains largely unexplored. Moreover, the role of evolutionary adaptation in assessing long-term ecological risks is unclear. Here, we investigated the effects of polystyrene nanoplastics (5 μg L-1) on Daphnia magna under varying MT (20 °C and 24 °C) and DTFs (0 °C, 5 °C, and 10 °C). Capitalizing on a space-for-time substitution approach, we further assessed how local thermal adaptation affect the sensitivity of Daphnia to nanoplastics under global warming. Our results indicated that nanoplastics exposure in general reduced heartbeat rate, thoracic limb activity and feeding rate, and increased CytP450, ETS activity and Hgb concentrations. Higher MT and DTFs enhanced these effects. Notably, clones originating from their respective sites performed better under their native temperature conditions, indicating local thermal adaptation. Warm-adapted low-latitude D. magna showed stronger nanoplastics-induced increases in CytP450, ETS activity and Hgb concentrations under local MT 24 °C, while cold-adapted high-latitude D. magna showed stronger nanoplastics-induced decreases in heartbeat rate, thoracic limb activity and feeding rate under high MT than under low MT.

Rapid Response of Daphnia magna Motor Behavior to Mercury Chloride Toxicity Based on Target Tracking

A rapid and timely response to the impacts of mercury chloride, which is indispensable to the chemical industry, on aquatic organisms is of great significance. Here, we investigated whether the YOLOX (improvements to the YOLO series, forming a new high-performance detector) observation system can be used for the rapid detection of the response of Daphnia magna targets to mercury chloride stress. Thus, we used this system for the real-time tracking and observation of the multidimensional motional behavior of D. magna. The results obtained showed that the average velocity (v¯), average acceleration (a¯), and cumulative travel (L) values of D. magna exposed to mercury chloride stress changed significantly under different exposure times and concentrations. Further, we observed that v¯, a¯ and L values of D. magna could be used as indexes of toxicity response. Analysis also showed evident D. magna inhibition at exposure concentrations of 0.08 and 0.02 mg/L after exposure for 10 and 25 min, respectively. However, under 0.06 and 0.04 mg/L toxic stress, v¯ and L showed faster toxic response than a¯, and overall, v¯ was identified as the most sensitive index for the rapid detection of D. magna response to toxicity stress. Therefore, we provide a strategy for tracking the motile behavior of D. magna in response to toxic stress and lay the foundations for the comprehensive screening of toxicity in water based on motile behavior.

Application of the Biological Toxicity Effect Ratio (BER) Method for Advancing Water Quality Criteria Derivation

Water quality criteria (WQC) serve as a scientific foundation for pollutant risk assessment and control in aquatic ecosystems. The development of regionally differentiated WQC tailored to specific regional characteristics has become an emerging trend. However, the current WQC is constrained by a lack of regional species toxicity data. To address these limitations, this study proposes the biological toxicity effect ratio (BER) method, which indirectly reflects the toxicity sensitivity of the overall aquatic ecosystem through the toxicity information on a limited number of species, enabling rapid WQC prediction. Using the established WQC in China and the USA as a case study, we combined mathematical derivation and data validation to evaluate the BER method. Among various species-taxon groups of freshwater organisms, planktonic crustaceans demonstrated the highest predictive accuracy. Our analysis further revealed that species toxicity sensitivity and regional variability jointly influence the prediction accuracy. Regardless of the evaluation indexes, planktonic crustaceans emerged as the most suitable species-taxon group for the BER method. Additionally, the BER method is particularly applicable to pollutants with conserved mechanisms across species. This study systematically explores the feasibility of using the BER method and offers new insights for deriving regionally differentiated WQC.

Ecotoxicological risk assessment on coagulation-flocculation in water/wastewater treatment: a systematic review

It is undeniable that removal efficiency is the main factor in coagulation-flocculation (C-F) process for wastewater treatment. However, as far as environmental safety is concerned, the ecotoxicological aspect of the C-F process needs to be examined further. In this study, a systematic review was performed based on publications related to the toxicity research in C-F technology for wastewater treatment. Through a series of screening steps, available toxicity studies were categorized into four themes, namely acute toxicity, phytotoxicity, cytotoxicity, and genotoxicity, which comprised 48 articles. A compilation of the methodologies executed for each theme was also outlined. The findings show that conventional metallic coagulants (e.g., alum, iron chloride, and iron sulfate) were less toxic when tested on test species such as Daphnia magna (water flea), Lattuca sativa (lettuce), and animal cells compared to synthetic polymers. Natural coagulants such as chitosan or Moringa oleifera were less toxic compared to metallic coagulants; however, inconsistent results were observed. Moreover, an advanced C-F (electrocoagulation) as well as integration between C-F and Fenton, adsorption, and photocatalytic does not significantly change the toxicological profile of the system. It was found that diverse coagulants and flocculants, species sensitivity, complexity in toxicity testing, and dynamic environmental conditions were some key challenges faced in this field. Finally, it was expected that advances in technology, interdisciplinary collaboration, and a growing awareness of environmental sustainability will drive efforts to develop more effective and eco-friendly coagulants and flocculants, improve toxicity testing methodologies, and enhance the overall efficiency and safety of water and wastewater treatment processes.

Adverse effects of the 5-alpha-reductase inhibitor finasteride on Daphnia magna: Endocrine system and lipid metabolism disruption

Finasteride, a steroid 5-alpha reductase inhibitor, is commonly used for the treatment of benign prostatic hyperplasia and hair loss. However, despite continued use, its environmental implications have not been thoroughly investigated. Thus, we investigated the acute and chronic adverse impacts of finasteride on Daphnia magna, a crucial planktonic crustacean in freshwater ecosystems selected as bioindicator organism for understanding the ecotoxicological effects. Chronic exposure (for 23 days) to finasteride negatively affected development and reproduction, leading to reduced fecundity, delayed first brood, reduced growth, and reduced neonate size. Additionally, acute exposure (< 24 h) caused decreased expression levels of genes crucial for reproduction and development, especially EcR-A/B (ecdysone receptors), Jhe (juvenile hormone esterase), and Vtg2 (vitellogenin), with oxidative stress-related genes. Untargeted lipidomics/metabolomic analyses revealed lipidomic alteration, including 19 upregulated and 4 downregulated enriched lipid ontology categories, and confirmed downregulation of metabolites. Pathway analysis implicated significant effects on metabolic pathways, including the pentose phosphate pathway, histidine metabolism, beta-alanine metabolism, as well as alanine, aspartate, and glutamate metabolism. This comprehensive study unravels the intricate molecular and metabolic responses of D. magna to finasteride exposure, underscoring the multifaceted impacts of this anti-androgenic compound on a keystone species of freshwater ecosystems. The findings emphasize the importance of understanding the environmental repercussions of widely used pharmaceuticals to protect biodiversity in aquatic ecosystems.

Quantitative structure-activity relationship predicting toxicity of pesticides towards Daphnia magna

Global pesticide usage reaching 2.7 million metric tons annually, brings a grave threat to non-target organisms, especially aquatic organisms, resulting in serious concerns. Predicting aquatic toxicity of pesticides towards Daphnia magna is significant. In this work, random forest (RF) algorithm, together with ten Dragon molecular descriptors, was successfully utilized to develop a quantitative structure-activity/toxicity relationship (QSAR/QSTR) model for the toxicity pEC50 of 745 pesticides towards Daphnia magna. The optimal QSTR model (RF Model I) based on the RF parameters of ntree = 50, mtry = 3 and nodesize = 5, yielded R2 = 0.877, MAE = 0.570, rms = 0.739 (training set of 596 pEC50), R2 = 0.807, MAE = 0.732, rms = 0.902 (test set of 149 pEC50), and R2 = 0.863, MAE = 0.602, rms = 0.774 (total set of 745 pEC50), which are accurate and satisfactory. The optimal RF model is comparable to other published QSTR models for Daphnia magna, although the optimal RF model possessed a small descriptor subset and dealt with a large dataset of pesticide toxicity pEC50. Thus, the investigation in this work provides a reliable, applicable QSTR model for predicting the toxicity pEC50 of pesticides towards Daphnia magna.

A Comprehensive Review of Nanoparticles: From Classification to Application and Toxicity

Nanoparticles are structures that possess unique properties with high surface area-to-volume ratio. Their small size, up to 100 nm, and potential for surface modifications have enabled their use in a wide range of applications. Various factors influence the properties and applications of NPs, including the synthesis method and physical attributes such as size and shape. Additionally, the materials used in the synthesis of NPs are primary determinants of their application. Based on the chosen material, NPs are generally classified into three categories: organic, inorganic, and carbon-based. These categories include a variety of materials, such as proteins, polymers, metal ions, lipids and derivatives, magnetic minerals, and so on. Each material possesses unique attributes that influence the activity and application of the NPs. Consequently, certain NPs are typically used in particular areas because they possess higher efficiency along with tenable toxicity. Therefore, the classification and the base material in the NP synthesis hold significant importance in both NP research and application. In this paper, we discuss these classifications, exemplify most of the major materials, and categorize them according to their preferred area of application. This review provides an overall review of the materials, including their application, and toxicity.

Lithium-ion battery components are at the nexus of sustainable energy and environmental release of per- and polyfluoroalkyl substances

Lithium-ion batteries (LiBs) are used globally as a key component of clean and sustainable energy infrastructure, and emerging LiB technologies have incorporated a class of per- and polyfluoroalkyl substances (PFAS) known as bis-perfluoroalkyl sulfonimides (bis-FASIs). PFAS are recognized internationally as recalcitrant contaminants, a subset of which are known to be mobile and toxic, but little is known about environmental impacts of bis-FASIs released during LiB manufacture, use, and disposal. Here we demonstrate that environmental concentrations proximal to manufacturers, ecotoxicity, and treatability of bis-FASIs are comparable to PFAS such as perfluorooctanoic acid that are now prohibited and highly regulated worldwide, and we confirm the clean energy sector as an unrecognized and potentially growing source of international PFAS release. Results underscore that environmental impacts of clean energy infrastructure merit scrutiny to ensure that reduced CO2 emissions are not achieved at the expense of increasing global releases of persistent organic pollutants.

Classification Model of Pesticide Toxicity in Americamysis bahia Based on Quantum Chemical Descriptors

A set of quantum chemical descriptors (molecular polarization, heat capacity, entropy, Mulliken net charge of the most positive hydrogen atom, APT charge of the most negative atom and APT charge of the most positive atom with hydrogen summed into heavy atoms) was successfully used to establish the classification models for the toxicity pLC50 of pesticides in Americamysis bahia. The optimal random forest model (Class Model A) yielded predictive accuracy of 100% (training set of 217 pesticides), 95.8% (test set of 72 pesticides) and 99.0% (total set of 289 pesticides), which were very satisfactory, compared with previous classification models reported for the toxicity of compounds in aquatic organisms. Therefore, it is reasonable to apply the quantum chemical descriptors associated with molecular structural information on molecular bulk, chemical reactivity and weak interactions, to develop classification models for the toxicity pLC50 of pesticides in A. bahia.

Cyanomethylquinolones as a New Class of Potential Multitargeting Broad-Spectrum Antibacterial Agents

This work identified a class of cyanomethylquinolones (CQs) and their carboxyl analogues as potential multitargeting antibacterial candidates. Most of the prepared compounds showed high antibacterial activities against most of the tested bacteria, exhibiting lower MIC values (0.125-2 μg/mL) than those of clinical norfloxacin, ciprofloxacin, and clinafloxacin. The low hemolysis, drug resistance, and cytotoxicity, as well as good predictive pharmacokinetics of active CQs and carboxyl analogues revealed their development potential. Furthermore, they could eradicate the established biofilm, facilitating bacterial exposure to these antibacterial candidates. These active compounds could induce bacterial death through multitargeting effects, including intercalating into DNA, up-regulating reactive oxygen species, damaging membranes directly, and impeding metabolism. Moreover, the highly active cyclopropyl CQ 15 exhibited more effective in vivo anti-MRSA potency than ciprofloxacin. These findings highlight the potential of CQs and their carboxyl analogues as multitargeting broad-spectrum antibacterial candidates for treating intractable bacterial infections.

Sol-Gel Synthesis of Silica-Poly (Vinylpyrrolidone) Hybrids with Prooxidant Activity and Antibacterial Properties

The present work deals with the sol-gel synthesis of silica-poly (vinylpyrrolidone) hybrid materials. The nanohybrids (Si-PVP) have been prepared using an acidic catalyst at ambient temperature. Tetramethyl ortosilane (TMOS) was used as a silica precursor. Poly (vinylpyrrolidone) (PVP) was introduced into the reaction mixture as a solution in ethanol with a concentration of 20%. The XRD established that the as-prepared material is amorphous. The IR and 29Si MAS NMR spectra proved the formation of a polymerized silica network as well as the hydrogen bonding interactions between the silica matrix and OH hydrogens of the silanol groups. The TEM showed spherical particle formation along with increased agglomeration tendency. The efficacy of SiO2/PVP nanoparticles as a potential antimicrobial agent against a wide range of bacteria was evaluated as bacteriostatic, using agar diffusion and spot tests. Combined effects of hybrid nanomaterial and antibiotics could significantly reduce the bactericidal concentrations of both the antibiotic and the particles, and they could also eliminate the antibiotic resistance of the pathogen. The registered prooxidant activity of the newly synthesized material was confirmative and explicatory for the antibacterial properties of the tested substance and its synergetic combination with antibiotics. The effect of new hybrid material on Crustacea Daphnia magna was also estimated as harmless under concentration of 0.1 mg/mL.

Synthesis and Characterization of Maghemite Nanoparticles Functionalized with Poly(Sodium 4-Styrene Sulfonate) Saloplastic and Its Acute Ecotoxicological Impact on the Cladoceran Daphnia magna

Using a modified co-precipitation method, 11(2) nm γ-Fe2O3 nanoparticles functionalized with PSSNa [Poly(sodium 4-styrenesulfonate)] saloplastic polymer were successfully synthesized, and their structural, vibrational, electronic, thermal, colloidal, hyperfine, and magnetic properties were systematically studied using various analytic techniques. The results showed that the functionalized γ-Fe2O3/PSSNa nanohybrid has physicochemical properties that allow it to be applied in the magnetic remediation process of water. Before being applied as a nanoadsorbent in real water treatment, a short-term acute assay was developed and standardized using a Daphnia magna biomarker. The ecotoxicological tests indicated that the different concentrations of the functionalized nanohybrid may affect the mortality of the Daphnia magna population during the first 24 h of exposure. A lethal concentration of 533(5) mg L-1 was found. At high concentrations, morphological changes were also seen in the body, heart, and antenna. Therefore, these results suggested the presence of alterations in normal growth and swimming skills. The main changes observed in the D. magna features were basically caused by the PSSNa polymer due to its highly stable colloidal properties (zeta potential > -30 mV) that permit a direct and constant interaction with the Daphnia magna neonates.

Rearing and Experimental Uses of Daphnia: Controlling Animal Nutrition and Assessing Lifespan and Life-History Traits

Caloric restriction has been found to extend the lifespan of many organisms including mammals and other vertebrates. With lifespans exceeding months to years, age-related experiments involving fish and mammals can be overtly costly, both in terms of time and funding. The freshwater crustacean, Daphnia, has a relatively short lifespan (∼50 to 100 days), which makes it a cost-effective alternative animal model for longevity and aging studies. Besides age-specific mortality, there are a suite of physiological responses connected to "healthspan" that can be tracked as these animals age including growth, reproduction, and metabolic rates. These responses can be complemented by assessment of molecular and cellular processes connected to aging and health. Lifespan and metabolism of this model organism is responsive to long studied modulators of aging, such as rearing temperature and nutritional manipulation, but also pharmacological agents that target aging, e.g., rapamycin, which adds to its usefulness as a model organism. Here we describe how to culture Daphnia for aging experiments including maintaining laboratory populations of Daphnia mothers, growing algal food, and manipulating nutrition of these animals. In addition, we provide methods for tracking common physiological and longevity responses of Daphnia. This protocol provides researchers planning to use this model organism with methods to establish and maintain Daphnia populations and to standardize their experimental approaches. © 2024 The Authors. Current Protocols published by Wiley Periodicals LLC. Basic Protocol 1: Culturing algae for Daphnia food Basic Protocol 2: General methods for culturing Daphnia Basic Protocol 3: Standardizing and controlling nutrition for experimental Daphnia Basic Protocol 4: Monitoring Daphnia lifespan Basic Protocol 5: Evaluating Daphnia health: Heart rate and respiration, body mass and growth rates, and reproduction.

Algal toxicity and food chain transport characteristics of three common bisphenols and their mixtures

Various bisphenols (BPs) have been frequently detected in the aquatic environment and coexist in the form of mixtures with potential huge risks. As we all know, food chain is a media by which BPs mixtures and their mixtures probably enter the organisms at different trophic levels due to their environmental persistence. As a result, the concentrations of BPs and their mixtures may continuously magnify to varying degrees, which can produce higher risks to different levels of organisms, and even human health. However, the related researches about mixtures are few due to the complexity of mixtures. So, the ternary BP mixtures were designed by the uniform design ray method using bisphenol A (BPA), bisphenol S (BPS) and bisphenol F (BPF) to investigate their food chain effects including bioconcentration and biomagnification. Here, Chlorella pyrenoidosa (C. pyrenoidosa) and Daphnia magna (D. magna) were selected to construct a food chain. The toxic effects of single BPs and their mixtures were also systematically investigated by the time-dependent microplate toxicity analysis (t-MTA) method. Toxicity interaction within the ternary mixture was analyzed by the concentration addition model (CA) and the deviation from the CA model (dCA). The results show that the C. pyrenoidosa and D. magna had obvious bioconcentration and biomagnification effects on BPs and their mixture. The mixture had the potential to enrich at higher nutrient levels. And BPF had the largest bioconcentration effect (BCF1 = 481.86, BCF2 = 772.02) and biomagnification effect (BMF = 1.6). Three BPs were toxic to C. pyrenoidosa by destroying algal cells and decreasing protein and chlorophyll contents, and their toxicity order was BPF > BPA > BPS. Moreover, their ternary mixture exhibits synergism with time/concentration-dependency. The obtained results are of significant reference value for objectively and accurately assessing the ecological and environmental risks of bisphenol pollutants.

Low-field, not low quality: 1D simplification, selective detection, and heteronuclear 2D experiments for improving low-field NMR spectroscopy of environmental and biological samples

Understanding environmental change is challenging and requires molecular-level tools to explain the physicochemical phenomena behind complex processes. Nuclear magnetic resonance (NMR) spectroscopy is a key tool that provides information on both molecular structures and interactions but is underutilized in environmental research because standard "high-field" NMR is financially and physically inaccessible for many and can be overwhelming to those outside of disciplines that routinely use NMR. "Low-field" NMR is an accessible alternative but has reduced sensitivity and increased spectral overlap, which is especially problematic for natural, heterogeneous samples. Therefore, the goal of this study is to investigate and apply innovative experiments that could minimize these challenges and improve low-field NMR analysis of environmental and biological samples. Spectral simplification (JRES, PSYCHE, singlet-only, multiple quantum filters), selective detection (GEMSTONE, DREAMTIME), and heteronuclear (reverse and CH3/CH2/CH-only HSQCs) NMR experiments are tested on samples of increasing complexity (amino acids, spruce resin, and intact water fleas) at-high field (500 MHz) and at low-field (80 MHz). A novel experiment called Doubly Selective HSQC is also introduced, wherein 1H signals are selectively detected based on the 1H and 13C chemical shifts of 1H-13C J-coupled pairs. The most promising approaches identified are the selective techniques (namely for monitoring), and the reverse and CH3-only HSQCs. Findings ultimately demonstrate that low-field NMR holds great potential for biological and environmental research. The multitude of NMR experiments available makes NMR tailorable to nearly any research need, and low-field NMR is therefore anticipated to become a valuable and widely used analytical tool moving forward.

Phytochemical, In Vitro, In Vivo, and In Silico Research on the Extract of Ajuga chamaepitys (L.) Schreb

The present study focuses on the chemical characterization of a dry extract obtained from the species Ajuga chamaepitys (L.) Schreb, evaluating its antioxidant properties, toxicity, and in silico profile. Quantitative analysis of the dry extract revealed a notable amount of phytochemical compounds: 59.932 ± 21.167 mg rutin equivalents (mg REs)/g dry weight, 45.864 ± 4.434 mg chlorogenic acid equivalents (mg ChAEs)/g dry weight and, respectively, 83.307 ± 3.989 mg tannic acid equivalents (TAEs)/g dry weight. By UHPLC-HRMS/MS, the following were quantified as major compounds: caffeic acid (3253.8 μg/g extract) and kaempherol (3041.5 μg/g extract); more than 11 types of polyphenolic compounds were quantified (genistin 730.2 μg/g extract, naringenin 395 μg/g extract, apigenin 325.7 μg/g extract, galangin 283.3 μg/g extract, ferulic acid 254.3 μg/g extract, p-coumaric acid 198.2 μg/g extract, rutin 110.6 μg/g extract, chrysin 90.22 μg/g extract, syringic acid 84.2 μg/g extract, pinocembrin 32.7 μg/g extract, ellagic acid 18.2 μg/g extract). The antioxidant activity was in accordance with the amount of phytochemical compounds: IC50DPPH = 483.6 ± 41.4 µg/mL, IC50ABTS•+ = 127.4 ± 20.2 µg/mL, and EC50FRAP = 491.6 ± 2 µg/mL. On the larvae of Artemia sp., it was found that the extract has a low cytotoxic action. In silico studies have highlighted the possibility of inhibiting the activity of protein kinases CDK5 and GSK-3b for apigenin, galangin, and kaempferol, with possible utility for treating neurodegenerative pathologies and neuropathic pain. Further studies are warranted to confirm the predicted molecular mechanisms of action and to further investigate the therapeutic potential in animal models of neurological disorders.

Analysis of pharmacokinetic profile and ecotoxicological character of cefepime and its photodegradation products

An important problem is the impact of photodegradation on product toxicity in biological tests, which may be complex and context-dependent. Previous studies have described the pharmacology of cefepime, but the toxicological effects of its photodegradation products remain largely unknown. Therefore, photodegradation studies were undertaken in conditions similar to those occurring in biological systems insilico, in vitro, in vivo and ecotoxicological experiments. The structures of four cefepime photodegradation products were determined by UPLC-MS/MS method. The calculated in silico ADMET profile indicates that carcinogenic potential is expected for compounds CP-1, cefepime, CP-2 and CP-3. The Cell Line Cytomotovity Predictor 2.0 tool was used to predict the cytotoxic effects of cefepime and related compounds in non-transformed and cancer cell lines. The results indicate that possible actions include: non-small cell lung cancer, breast adenocarcinoma, prostate cancer and papillary renal cell carcinoma. OPERA models were used to predict absorption, distribution, metabolism and excretion (ADME) endpoints, and potential bioactivity of CP-2, cefepime and CP-4. The results obtained in silico show that after 96h of exposure, cefepime, CP-1, CP-2, and CP-3 are moderately toxic in the zebrafish model, while CP-4 is highly toxic. On the contrary, cefepime is more toxic to T. platyurus (highly toxic) compared to the zebrafish model, similar to products CP-4, CP-3 and CP-2. In vitro cytotoxicity studies were performed by MTT assay and in vivo acute embryo toxicity studies using Danio rerio embryos and larvae. In vitro showed an increase in the cytotoxicity of products with the longest exposure period i.e. for 8 h. Additionally, at a concentration of 200 μg/mL, statistically significant changes in metabolic activity were observed depending on the irradiation time. In vivo studies conducted with Zebrafish showed that both cefepime and its photodegradation products have only low toxicity. Assessment of potential ecotoxicity included Microbiotests on invertebrates (Thamnotoxkit F and Daphtoxkit F), and luminescence inhibition tests (LumiMara). The observed toxicity of the tested solutions towards both Thamnocephalus platyurus and Daphnia magna indicates that the parent substance (unexposed) has lower toxicity, which increases during irradiation. The acute toxicity (Lumi Mara) of nonirradiated cefepime solution is low for all tested strains (<10%), but mixtures of cefepime and its photoproducts showed growth inhibition against all tested strains (except #6, Photobacterium phoreum). Generally, it can be concluded that after UV-Vis irradiation, the mixture of cefepime phototransformation products shows a significant increase in toxicity.