Environmental Concentrations of Herbicide Prometryn Render Stress-Tolerant Corals Susceptible to Ocean Warming.

Global warming has caused the degradation of coral reefs around the world. While stress-tolerant corals have demonstrated the ability to acclimatize to ocean warming, it remains unclear whether they can sustain their thermal resilience when superimposed with other coastal environmental stressors. We report the combined impacts of a photosystem II (PSII) herbicide, prometryn, and ocean warming on the stress-tolerant coral Galaxea fascicularis through physiological and omics analyses. The results demonstrate that the heat-stress-induced inhibition of photosynthetic efficiency in G. fascicularis is exacerbated in the presence of prometryn. Transcriptomics and metabolomics analyses indicate that the prometryn exposure may overwhelm the photosystem repair mechanism in stress-tolerant corals, thereby compromising their capacity for thermal acclimation. Moreover, prometryn might amplify the adverse effects of heat stress on key energy and nutrient metabolism pathways and induce a stronger response to oxidative stress in stress-tolerant corals. The findings indicate that the presence of prometryn at environmentally relevant concentrations would render corals more susceptible to heat stress and exacerbate the breakdown of coral Symbiodiniaceae symbiosis. The present study provides valuable insights into the necessity of prioritizing PSII herbicide pollution reduction in coral reef protection efforts while mitigating the effects of climate change.

Microbial community structure and co-occurrence network stability in seawater and microplastic biofilms under prometryn pollution in marine ecosystems.

Prometryn has been extensively detected in marine environment because of its widespread usage in agriculture and aquaculture and has been concerns since its serious effects on aquatic organisms. However, its impact on the microbial community in the marine ecosystem including seawater and biofilm is still unclear. Therefore, a short-term indoor microcosm experiment of prometryn exposure was conducted. This study found that prometryn had a more significant impact on the structure and stability of the microbial community in seawater compared to microplastic biofilms. Additionally, we observed that the assembly of the microbial community in biofilms was more affected by stochastic processes than in seawater under the exposure of prometryn. Our study provided evidence for the increasing impact of the microbial communities under the stress of prometryn and microplastics.

Prometryn exposure disrupts the intestinal health of Eriocheir sinensis: Physiological responses and underlying mechanism.

Most toxicity studies of prometryn in non-target aquatic animals have focused on hepatotoxicity, cardiotoxicity, embryonic developmental and growth toxicity, while studies on the molecular mechanisms of intestinal toxicity of prometryn are still unknown. In the current study, the intestinal tissues of the Chinese mitten crab (Eriocheir sinensis) were used to uncover the underlying molecular mechanisms of stress by 96-h acute in vivo exposure to prometryn. The results showed that prometryn activated the Nrf2-Keap1 pathway and up-regulated the expression of downstream antioxidant genes. Prometryn induced the expression of genes associated with non-specific immunity and autophagy, and induced apoptosis through the MAPK pathway. Interestingly, the significant up-or down-regulation of the above genes mainly occurred at 12 h- 24 h after exposure. Intestinal flora sequencing revealed that prometryn disrupted the intestinal normal barrier function mainly by reducing beneficial bacteria abundance, which further weakened the intestinal resistance to exogenous toxicants and caused an inflammatory response. Correlation analyses found that differential flora at the genus level had potential associations with gut stress-related genes. In conclusion, our study contributes to understanding the molecular mechanisms behind the intestinal stress caused by herbicides on aquatic crustaceans.

Mitochondrial and Proteasome Dysfunction Occurs in the Hearts of Mice Treated with Triazine Herbicide Prometryn.

Prometryn is a methylthio-s-triazine herbicide used to control the growth of annual broadleaf and grass weeds in many cultivated plants. Significant traces of prometryn are documented in the environment, mainly in waters, soil, and plants used for human and domestic consumption. Previous studies have shown that triazine herbicides have carcinogenic potential in humans. However, there is limited information about the effects of prometryn on the cardiac system in the literature, or the mechanisms and signaling pathways underlying any potential cytotoxic effects are not known. It is important to understand the possible effects of exogenous compounds such as prometryn on the heart. To determine the mechanisms and signaling pathways affected by prometryn (185 mg/kg every 48 h for seven days), we performed proteomic profiling of male mice heart with quantitative liquid chromatography-tandem mass spectrometry (LC-MS/MS) using ten-plex tandem mass tag (TMT) labeling. The data suggest that several major pathways, including energy metabolism, protein degradation, fatty acid metabolism, calcium signaling, and antioxidant defense system were altered in the hearts of prometryn-treated mice. Proteasome and immunoproteasome activity assays and expression levels showed proteasome dysfunction in the hearts of prometryn-treated mice. The results suggest that prometryn induced changes in mitochondrial function and various signaling pathways within the heart, particularly affecting stress-related responses.

Individual and combined effects of herbicide prometryn and nitrate enrichment at environmentally relevant concentrations on photosynthesis, oxidative stress, and endosymbiont community diversity of coral Acropora hyacinthus.

Nitrogen pollution and pesticides such as photosystem II (PSII) inhibitor herbicides have several detrimental impacts on coral reefs, including breakdown of the symbiosis between host corals and photosynthetic symbionts. Although nitrogen and PSII herbicide pollution separately cause coral bleaching, the combined effects of these stressors at environmentally relevant concentrations on corals have not been assessed. Here, we report the combined effects of nitrate enrichment and PSII herbicide (prometryn) exposure on photosynthesis, oxidative status and endosymbiont community diversity of the reef-building coral Acropora hyacinthus. Coral fragments were exposed in a mesocosm system to nitrate enrichment (9 µmol/L) and two prometryn concentrations (1 and 5 µg/L). The results showed that sustained prometryn exposure in combination with nitrate enrichment stress had significant detrimental impacts on photosynthetic apparatus [the maximum quantum efficiency of photosystem II (Fv/Fm), nonphotochemical quenching (NPQ) and oxidative status in the short term. Nevertheless, the adaptive mechanism of corals allowed the normal physiological state to be recovered following 1 µg/L prometryn and 9 µmol/L nitrate enrichment individual exposure. Moreover, exposure for 9 days was insufficient to trigger a shift in Symbiodiniaceae community. Most importantly, the negative impact of exposure to the combined environmental concentrations of 1 µg/L prometryn and 9 µmol/L nitrate enrichment was found to be significantly greater on the Fv/Fm, quantum yield of non-regulated energy dissipation [Y(NO)], NPQ, and oxidative status of corals compared to the impact of individual stressors. Our results show that interactions between prometryn stress and nitrate enrichment have a synergistic impact on the photosynthetic and oxidative stress responses of corals. This study provides valuable insights into combined effects of nitrate enrichment and PSII herbicides pollution for coral's physiology. Environmental concentrations of PSII herbicides may be more harmful to photosystems and antioxidant systems of corals under nitrate enrichment stress. Thus, future research and management of seawater quality stressors should consider combined impacts on corals rather than just the impacts of individual stressors alone.

Deep neural network and molecular docking supported toxicity profile of prometryn.

In this study, the versatile toxicity profile of prometryn herbicide on Allium cepa was investigated. In this context, 4 different groups were formed. While the control group was treated with distilled water, Groups II, III and IV were treated with 200 mg/L, 400 mg/L and 800 mg/L prometryn, respectively. After 72 h of germination, cytogenetic, biochemical, physiological and anatomical changes were investigated. As a result increase in malondialdehyde levels, decrease in glutathione level, changes in superoxide dismutase and catalase activities in root tip cells show that prometryn causes oxidative stress. The decrease in mitotic index values and the increase in the frequency of micronucleus and chromosomal abnormalities observed after prometryn treatment indicate genotoxic effects. The genotoxic effects may be due to the induced oxidative stress as well as the promethryn-DNA interaction. Molecular docking analyses revealed that prometryn interacts with various bases in DNA. As a result of the Comet assay, exposure to prometryn was found to cause DNA fragmentation. In physiological parameters final weight, germination percentage and root length decreased by 23.8%, 59.1% and 87.3%, respectively, in the 800 mg/L prometryn applied group. Deep neural network (DNN) model was optimized to predict the effects of different doses of prometryn on 4 different endpoints: micronucleus, mitotic index, chromosomal abnormalities and DNA Damage. The predicted data was found to be very similar to the actual data. The performance of the model was evaluated using MAE, MAPE, RMSE and R2, and these metrics indicate that the model performed well. Overall, the findings of this study suggest that the DNN model developed here is a valuable tool for predicting genotoxicity biomarkers in response to the application doses of prometryn, and has the potential to contribute to the development of safer and more sustainable agricultural practices.

Variation and characterization of prometryn in oysters (Crassostrea gigas) after seawater exposure.

Prometryn (PRO) is frequently detected in shellfish of international trade among triazine herbicides because of its wide application in agriculture and aquaculture worldwide. Nevertheless, the variations of PRO remain unclear in aquatic organisms, which affect the accuracy of their food safety risk assessment. In the present study, the tissue-specific accumulation, biotransformation, and potential metabolic pathway of PRO were reported in oyster species Crassostrea gigas for the first time. The experiments were conducted through semi-static seawater exposure with low and high concentrations of PRO (at nominal concentrations of 10 and 100 µg/L) via daily renewal over 22 days, followed by 16 days of depuration in clean seawater. The characterization of prometryn in oysters was then evaluated through the bioaccumulation behavior, elimination pathway and metabolic transformation, comparing with other organisms. The digestive gland and gonad were found to be the main target organs during uptake. In addition, the highest bioconcentration factor of 67.4 ± 4.1 was observed when exposed to low concentration. The level of PRO in oyster tissues rapidly decreased within 1 day during depuration, with an elimination rate of >90 % for the gill. Moreover, four metabolites of PRO were identified in oyster samples of exposed groups, including HP, DDIHP, DIP, and DIHP, in which HP was the major metabolite. Considering the mass percentage of hydroxylated metabolites higher than 90 % in oyster samples, PRO poses a larger threat to aquatic organisms than rat. Finally, the biotransformation pathway of PRO in C. gigas was proposed, the major metabolic process of which was hydroxylation along with N-dealkylation. Meanwhile, the newly discovered biotransformation of PRO in oyster indicates the importance of monitoring environmental levels of PRO in cultured shellfish, to prevent possible ecotoxicological effects as well as to ensure the safety of aquatic products.

A novel electrochemical aptasensor for ultrasensitive detection of herbicide prometryn based on its highly specific aptamer and Ag@Au nanoflowers.

Herbicide prometryn has become a common pollutant in aquatic environments and caused adverse impacts on ecosystems. This study developed an ultrasensitive electrochemical aptasensor for prometryn based on its highly affinitive and specific aptamer and Ag@Au nanoflowers (Ag@AuNFs) for signal amplification. Firstly, this study improved the Capture-SELEX strategy to screen aptamers and obtained aptamer P60-1, which had a high affinity (Kd: 23 nM) and could distinguish prometryn from its structural analogues. Moreover, the typical stem-loop structure in aptamer P60-1 was found to be the binding pocket for prometryn. Subsequently, an electrochemical aptasensor for prometryn was established using multiwalled carbon nanotubes and reduced graphene oxide as electrode substrate, Ag@Au NFs as signal amplification element, and aptamer P60-1 as recognition element. The aptasensor had a detection range of 0.16-500 ng/mL and a detection limit of 60 pg/mL, which was much lower than those of existing detection methods. The aptasensor had high stability and good repeatability, and could specifically detecting prometryn. Furthermore, the utility of the aptasensor was validated by measuring prometryn in environmental and biological components. Therefore, this study provides a robust and ultrasensitive aptasensor for accurate detection for prometryn pollution.

Design, synthesis and mechanism research of novel algicide based on bioactive fragments synthesis strategy.

The frequency and intensity of harmful cyanobacterial blooms (HCBs) are increasing all over the world, their prevention and control have become a great challenge. In this paper, a series of 1,3,4-thiadiazole thioacetamides (T series) were designed and synthesized as potential algaecides. Among them, the compound T3 showed its best algacidal activity against Synechocystis sp. PCC 6803 (PCC 6803, EC50 = 1.51 µM) and Microcystis aeruginosa FACHB 905 (FACHB905, EC50 = 4.88 µM), which was more effective than the lead compound L1 (PCC6803, EC50 = 7.7 µM; FACHB905, EC50 = 8.8 µM) and the commercially available herbicide prometryn (PCC6803, EC50 = 4.64 µM；FACHB905, EC50 = 6.52 µM). Meanwhile, T3 showed a lower inhibitory activity (EC50 = 12.76 µM) than prometryn (EC50 = 7.98 µM) to Chlorella FACHB1227, indicating that T3 had selective inhibition to prokaryotic algae (PCC6803, FACHB905) and eukaryotic algae (FACHB1227). Furthermore, the algacidal and anti-algae activities of T3 were significantly better than those of prometryn, while the toxicity of zebrafish and human cells was less than prometryn. Electron microscope, physiological, biochemical and metabonomic analysis showed that T3 interfered with light absorption and light conversion during photosynthesis by significantly reducing chlorophyll content, thus inhibited metabolic pathways such as the Calvin cycle and TCA cycle, and eventually led to the cell rupture of cyanobacteria. These results afforded further development of effective and safe algaecides.

Occurrence, fate, seasonal variability, and risk assessment of twelve triazine herbicides and eight related derivatives in source, treated, and tap water of Wuhan, Central China.

Triazine herbicides have been widely used, are frequently detected in aqueous environments and soils, and can cause acute or chronic toxicity to living organisms. We collected source water samples (n = 20) originating from the Hanshui River and the Yangtze River of Wuhan section, treated water samples (n = 20), and tap water samples (n = 169) in Wuhan, Central China during 2019 for determination of twelve triazine herbicides and their eight derivatives (collectively defined as TZs) and characterizing their fate during water treatment. Eighteen of the twenty TZs were detected in the source water. Atrazine (ATZ) had the highest concentrations (median: 22.4 ng/L) in the source water samples while DACT had the highest concentrations (median: 31.4 ng/L) in the treated water. "Tryns" (ametryn, prometryn, simetryn, terbutryn) were efficiently removed by conventional water treatment, while other target analytes were not; interestingly, hydroxypropazine and prometon increased significantly accompanied by prometryn disappearance, which implicated potential transformation pathways. In addition, "tryns" might be transformed into "tons" (atraton, prometon, secbumeton, terbumeton) by ozonation. In the tap water samples, diaminochlorotriazine had the highest concentrations (median: 34.9 ng/L) among the target analytes, followed by ATZ (18.3 ng/L), hydroxyatrazine (5.17 ng/L), deethylatrazine (5.00 ng/L), hydroxypropazine (3.20 ng/L), deisopropylatrazine (2.05 ng/L), hydroxydesethylatrazine (1.68 ng/L), and others. The TZs had the highest cumulative concentration in July in the tap water samples (median: 89.7 ng/L). This study found that ozonation in combination with activated carbon was more efficient in removing triazine herbicides, although "tryns" could also be transformed during conventional treatment. Ecological risk assessment showed moderate risks posed by hydroxyterbuthylazine, prometryn, and simetryn; the Hanshui River had higher risks than the Yangtze River, and July had higher risks than February. Human exposure to the TZs via water ingestion was low compared to the reference doses. This study characterized the occurrence of some new emerging TZs in the source water, their fate during drinking water treatment, and their seasonal variability in the tap water.

Characterization and catalytic mechanism of a direct demethylsulfide hydrolase for catabolism of the methylthiol-s-triazine prometryn.

Demethylthio is one of the most important ways for microorganisms to metabolize triazine herbicides. Previous studies have found that the initial reaction of prometryn catabolism in Leucobacter triazinivorans JW-1 was the hydroxylation of its methylthio group, however, the corresponding functional enzyme was not yet clear. In this study, the gene proA was responsible for the initial step of prometryn catabolism from the strain JW-1 was cloned and expressed, and the purified amidohydrolases ProA have the ability to transform prometryn to 2-hydroxypropazine and methanethiol. The optimized reaction temperature and pH of ProA were 45 °C and 7.0, respectively, and the kinetic constants Km and Vmax of ProA for the catalysis of prometryn were 32.6 µM and 0.09 µmol/min/mg, respectively. Molecular docking analyses revealed that different catalysis efficiency of ProA and TrzN (Nocardioides sp. C190) for prometryn and atrazine was due to non-covalent changes in amino acid residues. Our findings provide new insights into the understanding of s-triazine catabolism at the molecular level.

Herbicide prometryn adversely affects the development and reproduction of Tigriopus japonicus by disturbing the ecdysone signal pathway and chitin metabolic pathway.

Prometryn, a widely used triazine herbicide in agriculture and aquaculture, has been commonly detected in marine environments, but its effects on the marine copepod are unknown. In this study, marine copepod Tigriopus japonicus was chronically exposed to environmentally relevant concentrations of prometryn to investigate its impacts and potential mechanism of action. The results showed that 0.5, 5, and 50 µg/L prometryn delayed the first spawning time and hatching time, reduced the fecundity, and inhibited the population growth rate. Moreover, exposure to 0.5, 5 and 50 µg/L prometryn decreased food ingestion, the content of C and N elements, nutrient accumulation and body size, but increased the content of 20-hydroxyecdysone (20E). Transcriptome analysis showed that 50 µg/L prometryn down-regulated 1431 genes, which were mainly enriched in lysosome pathway and chitin binding and cuticle construction process. The results of qRT-PCR showed that the expression of key genes involved in juvenile hormone synthesis and chitin metabolic pathways were also inhibited after prometryn exposure. Molecular docking revealed that prometryn could bind to ecdysone receptor (EcR) and UDP-N-acetylglucosamine pyrophosphorylase (UAP), components of the ecdysteroid nuclear receptor complex. Therefore, environmental relevant prometryn delayed the molting and development of T. japonicus by disrupting the ecdysone signal pathway and chitin metabolic pathway through binding to EcR and UAP. This study provides new insights into toxic effects and molecular mechanisms of prometryn on marine copepods.

Developmental toxicity of prometryn induces mitochondrial dysfunction, oxidative stress, and failure of organogenesis in zebrafish (Danio rerio).

Prometryn, 2-methylthio-4,6-bis(isopropylamino)-1,3,5-triazine, is a selective thiomethyl triazine herbicide widely used to control unwanted weeds and harmful insects by inhibiting electron transport in target organisms. Despite having various advantages, herbicides pose as a major threat to the environment and human health due to persistent contamination, bioaccumulation, and damage to non-target organisms. In this study, the developmental toxicity of 5, 10, and 20 mg/L prometryn in zebrafish (Danio rerio) embryos was evaluated and compared to that of the solvent control for 96 h. Several transgenic zebrafish models (fli1a:eGFP, flk1:eGFP, olig2:dsRed and L-fabp:dsRed) were visually assessed to detect fluorescently tagged genes. Results showed that prometryn shortened body length, and induced yolk sac, heart edema, abnormal heart rate, and loss of viability. Fluorescence microscopy revealed that prometryn exposure caused defects in organ development, reactive oxygen species accumulation, and apoptotic cell death. Mitochondrial bioenergetics were also evaluated to determine the effect of prometryn on the electron transport chain activity and metabolic alterations. Prometryn was found to interfere with mitochondrial function, ultimately inhibiting energy metabolism and embryonic development. Collectively, our findings suggest that prometryn is a potential contaminate for non-target sites and organisms, especially aquatic, and emphasize the need to consider the toxic effects of prometryn.

Experimental study on effects of prometryn exposure scenarios on Microcystis aeruginosa growth and N and P concentrations.

Single exposure toxicity tests of herbicides like prometryn are commonly applied in studying ecological and environmental issues, but they are more likely exposed to microalgae through multiple applications of irrigation and water flow. The toxicity of prometryn towards Microcystis aeruginosa (M. aeruginosa) at different growth stages (different exposure period) was determined by single and multiple exposures (different exposure mode) through 39-day batch-experiment comparison study. Inhibition rates showed that M. aeruginosa growth was greatly inhibited by exposure to prometryn in a final concentration of 80 and 160 µg·L-1 (p < 0.05). Specifically, with the same prometryn exposure periods (lag or exponential phase) and concentrations, a single exposure displayed larger toxicity on M. aeruginosa than repetitive additions of prometryn in general according to inhibition rates. Moreover, with the same prometryn exposure modes and concentrations, inhibitory effect was higher with prometryn exposure in lag phase than that in exponential phase according to M. aeruginosa densities and inhibition rates. In general, variations of total dissolved phosphorus (TDP) and total dissolved nitrogen (TDN) with time responded negatively to M. aeruginosa growth, and added prometryn inhibits the utilization rate of both P and N. Logistic function was well used to describe algae densities (R2 = 0.979 ~ 0.995), growth rates (R2 = 0.515 ~ 0.731), specific growth rates (R2 = 0.301 ~ 0.648) and inhibition rates (R2 = 0.357 ~ 0.946) along with its combination with Monod function. In addition, results showed that shifts of limiting nutrients could be prompted by not only M. aeruginosa growth but also prometryn exposure scenarios. This study provides a basis for studying the potential harm of prometryn to the ecological environment.

Isolation and characterization of cyromazine degrading Acinetobacter sp. ZX01 from a Chinese ginger cultivated soil.

Cyromazine, a symmetrical triazine insecticide, is used to control dipteran larvae in chicken manure by feeding to the poultry, flies on animals, and leafminers in vegetables. Its extensive use has resulted in the widespread contamination in the environment. In the current study, a cyromazine degrading bacterium (designated strain ZX01) was isolated and characterized from a Chinese ginger cultivated soil by selective enrichment culture method. On the basis of morphological, biochemical characteristics, and 16S rRNA gene sequence, this bacterium showed strong similarity to the Pseudomonadales members and was closely related to the Acinetobacter baumannii group. Spectrophotometric and HPLC analyses revealed that strain ZX01 degraded cyromazine and utilized it as the sole carbon source for its growth. This process hydrolyzes cyromazine to melamine. Strain ZX01 degraded most of the cyromazine in 60 h. Besides, its substrate specificity against four symmetrical triazine herbicides, one triazinone herbicide, as well as 10 insecticides and its antibiotic sensitivity towards eight commercial antibiotics were also tested. At the concentration of 100 µg/mL for 60 h, it could effectively degrade a variety of different pesticides, including atrazine, prometon, simazine, prometryn, enitrothion, diazinon, cypermethrin, and acetamiprid, and the degradation was in the range of 71-87%. In particular, melamine, the main degradation product of cyromazine, was degraded by 47.3%. This microorganism was sensitive to chloramphenicol and tetracycline and intermediate to amoxicillin and trimethoprim. These results highlight that strain ZX01 can be used as a potential biological agent for the remediation of soil, water, or crop contaminated with cyromazine and other symmetrical triazine insecticides.

Occurrence and Removal of Triazine Herbicides during Wastewater Treatment Processes and Their Environmental Impact on Aquatic Life.

Wastewater treatment plants (WWTPs) represent a major point source for pesticide residue entry to aquatic environment and may threaten ecosystems and biodiversity in urban area. Triazine herbicides should be paid attention to for their ubiquitous occurrence in the environment and long-term residue. The present study aimed to quantify eleven compounds of triazine herbicides during wastewater treatment processes. The solid phase extraction and gas-chromatography mass spectrometry (GC-MS) determination method were developed to identify the target herbicides with approving sensitivity. The pollution levels, removal rates of eleven triazine herbicides along five different treatment stages in WWTP were investigated. The results showed that three herbicides including atrazine, simetryn and prometryn were detected. Their concentrations in influent were among 28.79 to 104.60 ng/L. Their total removal rates from influent to effluent were 14.92%, 10.79% and 4.41%, respectively indicating that they were difficult to be effectively remove during wastewater treatment. Regarding the negative impact of triazine herbicides discharged from WWTPs on downstream water quality and aquatic life, the environmental risks were assessed by calculating the Environmental Relevance of Pesticides from Wastewater Treatment Plants Index (ERPWI) and water cycle spreading index (WCSI). The risk assessment results denoted the possible high risks for atrazine and simetryn to alage, and simetryn concurrently posed a high risk for the daphnia, while prometryn was at medium risk to alage. Atrazine and simetryn in effluent posed high risk for algae, meanwhile, simetryn had high risk for Daphnia. These results suggested a possible threat to the aquatic environment, rendering in this way the ERPWI method as a useful assessment tool. Further extensive study is needed for atrazine and simetryn in order to better understand their migration mechanism in aquatic environment.

Acute toxicity, bioaccumulation and elimination of prometryn in tilapia (Oreochromis niloticus).

Tilapia juvenile (Oreochromis niloticus) (mean weight 50.00 ± 10.00 g) were aqueous exposed to different concentrations of the herbicide prometryn to investigate its acute toxicity, bioaccumulation and uptake and elimination rates. First, a 96-h acute toxicity test was carried out. The resulting 96 h LC50 was 5.49 mg/L, and the 96 h LC10 was 5.02 mg/L. Then, fish were exposed to 0.55 mg/L (1/10 96 h LC50) and 0.055 mg/L (1/100 96 h LC50) of prometryn solution for 28 days, followed by 14 days of elimination in clean groundwater. The result shows that in both water and tissues, prometryn concentrations fluctuated during the exposure period, indicating that steady state was not reached. The bioaccumulation of prometryn was the highest in liver, followed by gill, muscle and blood. The accumulated concentration levels in various tissues were always higher in the high concentration compared to the low concentration. The highest accumulated concentration of prometryn in various tissues in the 0.055 mg/L treatment were for muscle: 0.136 ± 0.0616 mg/kg (1 d), liver: 3.74 ± 2.95 mg/kg (7 d), gill: 0.971 ± 1.45 mg/kg (1 d) and blood: 0.0716 ± 0.0669 mg/kg (22 d). In the 0.55 mg/L treatment, the highest levels were for muscle: 1.27 ± 0.284 mg/kg (1 d), liver: 16.9 ± 12.7 mg/kg (7 d), gill: 8.11 ± 3.02 mg/kg (1 d) and blood: 0.751 ± 0.0775 mg/kg (22 d). The highest bioconcentration factor (BCF) of 93.1 was observed in the liver when exposed to the low concentration. Besides, for other tissues, the highest BCF were for muscle: 5.76, gill: 32.3 and blood: 2.91, all observed in the 0.55 mg/L treatment. Most of the accumulated prometryn was removed from all tissues within 24 h after the organisms were transferred to clean water. However, management of using prometryn in China aquaculture should be improved to prevent possible ecotoxicological effects and ensure food safety.

Environmental relevant herbicide prometryn induces developmental toxicity in the early life stages of marine medaka (Oryzias melastigma) and its potential mechanism.

Triazine herbicides have been widely detected in marine environments because of their extensive usage in agriculture, but their impact on marine organisms is unclear. In this study, marine medaka (Oryzias melastigma) embryos were exposed to 0, 1, 10, 100, and 1000 µg/L prometryn, one of the most detected triazine herbicides, to investigate its potential effects. The results showed that 1, 10, 100, and 1000 µg/L prometryn not only induced yolk sac shrinkage and heart malformations, but also significantly delayed the hatching time and increased the heart rate and hatching failure rate of embryos. Moreover, 1, 10, 100, and 1000 µg/L prometryn caused obvious malformations and decreased the body length of the newly hatched larvae. After 21 d of exposure, increased larval death rate, decreased body length and width, and higher lipid accumulation were observed in the larvae from all prometryn groups. Furthermore, prometryn exposure upregulated the expression levels of cardiac development-related genes GATA, COX, ATPase, SmyD1, EPO, FGF8, NKX2, and BMP4 in the larvae. Transcriptome analysis revealed that 10 µg/L prometryn upregulated 604 genes, and the topmost pathways of differentially expressed genes were the complement and coagulation cascades and AMPK signaling pathways. qPCR results confirmed that prometryn exposure significantly increased the expression levels of the complement and coagulation cascade genes f2, f5, c3, and c5. This study demonstrated that environmentally relevant concentrations of prometryn induced significant toxicity in the early life stages of marine medaka. Therefore, the health risks of herbicides to marine organisms are of great concern.

Effects of co-exposure of the triazine herbicides atrazine, prometryn and terbutryn on Phaeodactylum tricornutum photosynthesis and nutritional value.

Triazine herbicides are widely used in agricultural production, and large amounts of herbicide residue enter the ocean through surface runoff. In this study, the toxicities of the triazine herbicides atrazine, prometryn and terbutryn (separately and mixed) to Phaeodactylum tricornutum were investigated. The EC50 values of atrazine, prometryn and terbutryn were 28.38 µg L-1, 8.86 µg L-1, and 1.38 µg L-1, respectively. The EC50 of an equitoxic mixture of the three herbicides was 0.78 TU, indicating that they had synergistic effects. The equitoxic mixture accumulated in P. tricornutum, which damaged chloroplast and mitochondria structures and significantly decrease the biomass, levels of key cellular components (such as chlorophyll a (chl a), carbon (C) and nitrogen (N) content, fatty acid content) and the effective photochemical quantum yield of photosystem II (PSII, ∆Fv/Fm). The mixture also downregulated key genes in the light response (PsbD, PetF), dark response (PGK, PRK), tricarboxylic acid (TCA) cycle (CS, ID, OGD, and MS) and fatty acid synthesis (FABB, SCD, and PTD9). P. tricornutum partially alleviates the effects of the mixture on photosynthesis and fatty acid synthesis by upregulating PetD, PsaB, RbcL and FabI expression. The triazine herbicide mixture reduced the biomass and nutritional value of marine phytoplankton by inhibiting photosynthesis and energy metabolism.

Ultrasensitive electrochemiluminescence sensor based on perovskite quantum dots coated with molecularly imprinted polymer for prometryn determination.

A highly effective molecularly imprinted electrochemiluminescence sensor was constructed for prometryn determination in environmental and biological samples by using perovskite quantum dots coated with a molecularly imprinted silica layer (MIP/CsPbBr3-QDs) as the recognition and response element. MIP/CsPbBr3-QDs were immobilized on a glassy carbon electrode (GCE) through electropolymerization, and the electrochemiluminescence (ECL) response of MIP/CsPbBr3-QDs could be motivated under the condition of H2O2 as co-reactant. ECL signal was selectively quenched with prometryn by hindering electron transfer and directly proportional to the logarithm of prometryn concentration (0.10-500.0 µg/L) with a correlation coefficient of 0.9960. Limits of detection in fish and seawater samples were 0.010 µg/kg and 0.050 µg/L, respectively. Excellent recoveries of 88.0%-106.0% were acquired for fish and seawater samples with a relative standard deviation below 4.2%. The constructed MIECL sensor based on MIP/CsPbBr3-QDs showed good stability, accuracy, and precision for sensitive detection of prometryn in aquaculture products and environmental samples.