Development and application of bisphenol S electrochemical immunosensor and iridium oxide nanoparticle-based lateral flow immunoassay.

Bisphenol S (BPS) is a common pollutant in the environment and has posed a potential threat to aquatic animals and human health. To accurately assess the pollution level and ecological risk of BPS, there is an urgent need to establish simple and sensitive detection methods for BPS. In this study, BPS complete antigen was successfully prepared by introducing methyl 4-bromobutyrate and coupling bovine serum albumin (BSA). The monoclonal antibody against BPS (anti-BPS mAb) with high affinity (1: 256,000) was developed based on the BPS complete antigen, which showed low cross-reactivity with BPS structural analogues. Then, an electrochemical immunosensor was constructed to detect BPS using multi-walled carbon nanotubes and gold nanoflower composites as signal amplification elements and using anti-BPS mAb as the probe. The electrochemical immunosensor had a linear range from 1 to 250 ng⋅mL-1 and a limit of detection (LOD) down to 0.6 ng⋅mL-1. Additionally, a more stable and sensitive lateral flow immunoassay (LFIA) for BPS was developed based on iridium oxide nanoparticles, with a visual detection limit of 1 ng⋅mL-1, which was 10 times lower than that of classical Au-NPs LFIA. After evaluation of their stability and specificity, the reliability of these two methods were further validated by measuring BPS concentrations in the water and fish tissues. Thus, this study provides sensitive, robust and rapid methods for the detection of BPS in the environment and organisms, which can provide a methodological reference for monitoring environmental contaminants.

Functional characterization of a novel Chlamydomonas reinhardtii hydrolase involved in biotransformation of chloramphenicol.

Microalgae-based biotechnology is one of the most promising alternatives to conventional methods for the removal of antibiotic contaminants from diverse water matrices. However, current knowledge regarding the biochemical mechanisms and catabolic enzymes involved in microalgal biodegradation of antibiotics is scant, which limits the development of enhancement strategies to increase their engineering feasibility. In this study, we investigated the removal dynamics of amphenicols (chloramphenicol, thiamphenicol, and florfenicol), which are widely used in aquaculture, by Chlamydomonas reinhardtii under different growth modes (autotrophy, heterotrophy, and mixotrophy). We found C. reinhardtii removed >92 % chloramphenicol (CLP) in mixotrophic conditions. Intriguingly, gamma-glutamyl hydrolase (GGH) in C. reinhardtii was most significantly upregulated according to the comparative proteomics, and we demonstrated that GGH can directly bind to CLP at the Pro77 site to induce acetylation of the hydroxyl group at C3 position, which generated CLP 3-acetate. This identified role of microalgal GGH is mechanistically distinct from that of animal counterparts. Our results provide a valuable enzyme toolbox for biocatalysis and reveal a new enzymatic function of microalgal GGH. As proof of concept, we also analyzed the occurrence of these three amphenicols and their degradation intermediate worldwide, which showed a frequent distribution of the investigated chemicals at a global scale. This study describes a novel catalytic enzyme to improve the engineering feasibility of microalgae-based biotechnologies. It also raises issues regarding the different microalgal enzymatic transformations of emerging contaminants because these enzymes might function differently from their counterparts in animals.

Responses of coastal phytoplankton communities to seasonal herbicide inputs: Tolerance or degeneration?

Herbicide-induced phytoplankton inhibition threatens coastal biodiversity and ecosystem function. Although studies employing single-frequence exposure aid in understanding the phytoplankton community's responses to herbicides, it's difficult to objectively assess their response to cyclic herbicide inputs (long-term low-dose and short-term high-dose) in marine ecosystems. Here, we analyzed the concentration and distribution of herbicides in global coastal waters and simulated this cyclic process through a two-phase atrazine exposure mesocosm experiment and laboratory tests. The results indicated that, the herbicide concentrations (0.82 nmol L-1, 95 % CI 0.55, 1.74) from May to August were significantly higher than that (0.14 nmol L-1, 95 % CI 0.02, 0.38) in the remainder months, and highest concentrations typically emerged in summer; the changes in phytoplankton community composition under environmental concentrations of triazine herbicides could recover in the short term, but sustained inhibition of biomass was produced; the dominant populations were more likely to develop tolerance through preexposure and recover from subsequent impulse of atrazine, but this process was accompanied by the loss of rare groups and a decrease in biodiversity, meanwhile, affected the bacterial community in phycosphere. Consequently, we considered that the cyclic herbicide inputs may cause more detrimental effects than single-frequence exposure, potentially leading to a large-scale decline in coastal primary productivity.

Prenatal exposure to bisphenol AF causes toxicities in liver, spleen, and kidney tissues of SD rats.

As a replacement for bisphenol A (BPA), bisphenol AF (BPAF) showed stronger maternal transfer and higher fetal accumulation than BPA. Therefore, concerns should be raised about the health risks of maternal exposure to BPAF during gestation on the offspring. In this study, SD rats were exposed to BPAF (0, 50, and 100 mg/kg/day) during gestation to investigate the bioaccumulation and adverse effects in liver, spleen, and kidney tissues of the offspring at weaning period. Bioaccumulation of BPAF in these tissues with concentrations ranging from 1.56 ng/mg (in spleen of males) to 55.44 ng/mg (in liver of females) led to adverse effects at different biological levels, including increased relative weights of spleen and kidneys, histopathological damage in liver, spleen, and kidney, organ functional damage in liver, spleen, and kidney, upregulated expression of genes related to lipid metabolism (in liver), oxidative stress response (in kidney), immunity and inflammatory (in spleen). Furthermore, dysregulated metabolomics was identified in spleen, with 217 differential metabolites screened and 9 KEGG pathways significantly enriched. This study provides a comprehensive insight into the systemic toxicities of prenatal exposure to BPAF in SD rats. Given the broad applications and widespread occurrence of BPAF, its safety should be re-considered.

A Potential Neurotoxic Mechanism: Bisphenol S-Induced Inhibition of Glucose Transporter 1 Leads to ATP Excitotoxicity in the Zebrafish Brain.

Many environmental pollutants have neurotoxic effects, but the initial molecular events involved in these effects are unclear. Here, zebrafish were exposed to the neurotoxicant bisphenol S (BPS, 1, 10, or 100 µg/L) from the embryonic stage to the larval stage to explore the ability of BPS to interfere with energy metabolism in the brain. BPS, which is similar to a glucose transporter 1 (GLUT1) inhibitor, inhibited GLUT1 function but increased mitochondrial activity in the brains of larval zebrafish. Interestingly, GLUT1 inhibitor treatment and BPS exposure did not reduce energy production in the brain; instead, they increased ATP production by inducing the preferential use of ketone bodies. Moreover, BPS promoted the protein expression of the purinergic 2X receptor but inhibited the purinergic 2Y-mediated phosphatidylinositol signaling pathway, indicating that excess ATP acts as a neurotransmitter to activate the purinergic 2X receptor under the BPS-induced restriction of GLUT1 function. BPS-induced inhibition of GLUT1 increased the number of neurons but promoted apoptosis by activating ATP-purinergic 2X receptors in the brain, causing ATP excitatory neurotoxicity. Our data reveal a potential neurotoxic mechanism induced by BPS that may represent a new adverse outcome pathway.

Pollution level and ecological risk assessment of triazine herbicides in Laizhou Bay and derivation of seawater quality criteria.

Triazine herbicides are widely used in agriculture and have become common pollutants in marine environments. However, the spatiotemporal distribution characteristics and water quality criteria (WQC) of triazine herbicides are still unclear. This study found that triazine herbicides had a high detection rate of 100 % in surface seawater of Laizhou Bay, China, with average concentrations of 217.61, 225.13, 21.97, and 1296.72 ng/L in March, May, August, and October, respectively. Moreover, estuaries were important sources, and especially the Yellow River estuary exhibited the highest concentrations of 16,115.86 ng/L in October. The 10 triazine herbicides were detected in the sediments of Laizhou Bay, with a concentration ranging from 0.14-1.68 µg/kg. Atrazine and prometryn accounted for 33.41 %-59.10 % and 28.93 %-50.06 % of the total triazine herbicides in the seawater, and prometryn had the highest proportion (63.50 %) in the sediments. Correlation analysis revealed that triazine herbicides led to the loss of plankton biodiversity, which further decreased the dissolved oxygen. In addition, this study collected 45 acute toxicity data and 22 chronic toxicity data of atrazine, 16 acute toxicity data of prometryn, and supplemented with toxicity experiments of prometryn on marine organisms. Based on the toxicity database, the WQCs of atrazine and prometryn were derived using species sensitivity distribution. The overall risk probability of atrazine and prometryn were both less than 1.75 % in the Laizhou Bay, indicating an acceptable risk. This study not only clarified the pollution status and ecological risk of triazine herbicides, but also provided scientific basis for their environmental management standards.

Bisphenol S causes excessive estrogen synthesis by activating FSHR and the downstream cAMP/PKA signaling pathway.

Estrogen excess in females has been linked to a diverse array of chronic and acute diseases. Emerging research shows that exposure to estrogen-like compounds such as bisphenol S leads to increases in 17ß-estradiol levels, but the mechanism of action is unclear. The aim of this study was to reveal the underlying signaling pathway-mediated mechanisms, target site and target molecule of action of bisphenol S causing excessive estrogen synthesis. Human ovarian granulosa cells SVOG were exposed to bisphenol S at environmentally relevant concentrations (1 µg/L, 10 µg/L, and 100 µg/L) for 48 h. The results confirms that bisphenol S accumulates mainly on the cell membrane, binds to follicle stimulating hormone receptor (FSHR) located on the cell membrane, and subsequently activates the downstream cyclic adenosine monophosphate/protein kinase A (cAMP/PKA) signaling pathway, leading to enhanced conversion of testosterone to 17ß-estradiol. This study deepens our knowledge of the mechanisms of environmental factors in pathogenesis of hyperestrogenism.

Long-term exposure to prometryn damages the visual system and changes color preference of female zebrafish (Danio rerio).

Color vision, initiated from the cone photoreceptors, is essential for fish to obtain environmental information. Although the visual impairment of triazine herbicide prometryn has been reported, data on the effect of herbicide such as prometryn on natural color sensitivity of fish is scarce. Here, zebrafish were exposed to prometryn (0, 1, 10, and 100 µg/L) from 2 h post-fertilization to 160 days post-fertilization, to explore the effect and underlying mechanism of prometryn on color perception. The results indicated that 10 and 100 µg/L prometryn shortened the height of red-green cone cells, and down-regulated expression of genes involved in light transduction pathways (arr3a, pde6h) and visual cycle (lrata, rpe65a); meanwhile, 1 µg/L prometryn increased all-trans-retinoic acid levels in zebrafish eyes, and up-regulated the expression of genes involved in retinoid metabolism (rdh10b, aldh1a2, cyp26a1), finally leading to weakened red and green color perception of female zebrafish. This study first clarified how herbicide such as prometryn affected color vision of a freshwater fish after a long-term exposure from both morphological and functional disruption, and its hazard on color vision mediated-ecologically relevant tasks should not be ignored.

Rapid Membrane-Penetrating Hybrid Peptides Achieve Efficient Dual Antimicrobial and Antibiofilm Activity through a Triple Bactericidal Mechanism.

Antimicrobial peptides (AMPs) are a type of biomaterial used against multidrug resistant (MDR) bacteria. This study reports the design of a peptide family rich in tryptophan and lysine obtained by optimizing a natural AMP using single factor modification and pheromone hybridization to expedite the penetration and improve the antimicrobial activity of AMPs. S-4, L-4, and P-4 showed α-helical structures, exhibited extremely fast membrane penetration rates in vitro, and could kill MDR bacteria efficiently within 30 min. Intracellular fluorescence localization suggested rapid membrane-penetrating of AMPs within 1 min, making it more difficult for bacteria to develop resistance. Furthermore, they could effectively inhibit and destroy bacterial biofilms with dual antimicrobial and antibiofilm activity. In the treatment of skin infections caused by MDR-Acinetobacter baumannii in vivo , AMPs could effectively alleviate inflammation without toxic side effects. Additionally, the triple antimicrobial damage of AMPs was described in detail. AMPs rapidly penetrate the cell membrane, inducing cell membrane damage, triggering oxidative damage with a storm of reactive oxygen species and leading to bacterial death through leakage of cellular contents by complexing with DNA. The multiple damage is an important means by which AMPs can prevent bacterial resistance adequately.

Ecological risk assessment of heavy metals in desulfurized seawater discharged from a coal-fired power plant in Qingdao.

Despite the prevalence of discharge of large volumes of heavy-metal-bearing seawater from coal-fired power plants into adjacent seas, studies on the associated ecological risks remain limited. This study continuously monitored concentrations of seven heavy metals (i.e. As, Cd, Cr, Cu, Hg, Pb, and Zn) in surface seawater near the outfall of a coal-fired power plant in Qingdao, China over three years. The results showed average concentrations of As, Cd, Cr, Cu, Hg, Pb, and Zn of 2.63, 0.33, 2.97, 4.63, 0.008, 0.85, and 25.00 µg/L, respectively. Given the lack of data on metal toxicity to local species, this study investigated species composition and biomass near discharge outfalls and constructed species sensitivity distribution (SSD) curves with biological flora characteristics. Hazardous concentrations for 5% of species (HC5) for As, Cd, Cr, Cu, Hg, Pb, and Zn derived from SSDs constructed from chronic toxicity data for native species were 3.23, 2.22, 0.06, 2.83, 0.66, 4.70, and 11.07 µg/L, respectively. This study further assessed ecological risk of heavy metals by applying the Hazard Quotient (HQ) and Joint Probability Curve (JPC) based on long-term heavy metal exposure data and chronic toxicity data for local species. The results revealed acceptable levels of ecological risk for As, Cd, Hg, and Pb, but unacceptable levels for Cr, Cu, and Zn. The order of studied heavy metals in terms of ecological risk was Cr > Cu ≈ Zn > As > Cd ≈ Pb > Hg. The results of this study can guide the assessment of ecological risk at heavy metal contaminated sites characterized by relatively low heavy metal concentrations and high discharge volumes, such as receiving waters of coal-fired power plant effluents.

Bisphenols can promote antibiotic resistance by inducing metabolic adaptations and natural transformation.

Whether bisphenols, as plasticizers, can influence bacterial uptake of antibiotic resistance genes (ARGs) in natural environment, as well as the underlying mechanism remains largely unknown. Our results showed that four commonly used bisphenols (bisphenol A, S, F, and AF) at their environmental relative concentrations can significantly promote transmission of ARGs by 2.97-3.56 times in Acinetobacter baylyi ADP1. Intriguingly, we observed ADP1 acquired resistance by integrating plasmids uptake and cellular metabolic adaptations other than through reactive oxygen species mediated pathway. Metabolic adaptations including upregulation of capsules polysaccharide biosynthesis and intracellularly metabolic enzymes, which enabled formation of thicker capsules for capturing free plasmids, and degradation of accumulated compounds. Simultaneously, genes encoding DNA uptake and translocation machinery were incorporated to enhance natural transformation of antibiotic resistance carrying plasmids. We further exposed aquatic fish to bisphenols for 120 days to monitor their long-term effects in aquatic environment, which showed that intestinal bacteria communities were dominated by a drug resistant microbiome. Our study provides new insight into the mechanism of enhanced natural transformation of ARGs by bisphenols, and highlights the investigations for unexpectedly-elevated antibiotic-resistant risks by structurally related environmental chemicals.

Trophic transfer of micro- and nanoplastics and toxicity induced by long-term exposure of nanoplastics along the rotifer (Brachionus plicatilis)-marine medaka (Oryzias melastigma) food chain.

Microplastics (MPs) and nanoplastics (NPs) are emerging pollutants in the ocean, but their transfer and toxicity along the food chains are unclear. In this study, a marine rotifer (Brachionus plicatilis)-marine medaka (Oryzias melastigma) food chain was constructed to evaluate the transfer of polystyrene MPs and NPs (70 nm, 500 nm, and 2 µm, 2000 µg/L) and toxicity of 70 nm PS-NPs (0, 20, 200, and 2000 µg/L) on marine medaka after long-term food chain exposure. The results showed that the amount of 70 nm NPs accumulated in marine medaka was 1.24 µg/mg, which was significantly higher than that of 500 nm NPs (0.87 µg/mg) and 2 µm MP (0.69 µg/mg). Long-term food chain exposure to NPs caused microflora dysbiosis, resulting in activation of toll-like receptor 4 (TLR4) pathway, which induced liver inflammation. Moreover, NPs food chain exposure increased liver and muscle tissue triglyceride and lactate content, but decreased the protein, sugar, and glycogen content. NPs food chain exposure impaired reproductive function and inhibited offspring early development, which might pose a threat to the sustainability of marine medaka population. Overall, the study revealed the transfer of MPs and NPs and the effects of NPs on marine medaka along the food chain.

Herbicide leakage into seawater impacts primary productivity and zooplankton globally.

Predicting the magnitude of herbicide impacts on marine primary productivity remains challenging because the extent of worldwide herbicide pollution in coastal waters and the concentration-response relationships of phytoplankton communities to multiple herbicides are unclear. By analyzing the spatiotemporal distribution of herbicides at 661 bay and gulf stations worldwide from 1990 to 2022, we determined median, third quartile and maximum concentrations of 12 triazine herbicides of 0.18 nmol L-1, 1.27 nmol L-1 and 29.50 nmol L-1 (95%Confidence Interval: CI 1.06, 1.47), respectively. Under current herbicide stress, phytoplankton primary productivity was inhibited by more than 5% at 25% of the sites and by more than 10% at 10% of the sites (95%CI 3.67, 4.34), due to the inhibition of highly abundant sensitive species, community structure/particle size succession (from Bacillariophyta to Dinophyceae and from nano-phytoplankton to micro-phytoplankton), and resulting growth rate reduction. Concurrently, due to food chain cascade effects, the dominant micro-zooplankton population shifted from larger copepod larvae to smaller unicellular ciliates, which might prolong the transmission process in marine food chain and reduce the primary productivity transmission efficiency. As herbicide application rates on farmlands worldwide are correlated with residues in their adjacent seas, a continued future increase in herbicide input may seriously affect the stability of coastal waters.

Occurrence, ecological risk, and advanced removal methods of herbicides in waters: a timely review.

Coastal pollution caused by the importation of agricultural herbicides is one of the main environmental problems that directly affect the coastal primary productivity and even the safety of human seafood. It is urgent to evaluate the ecological risk objectively and explore feasible removal strategies. However, existing studies focus on the runoff distribution and risk assessment of specific herbicides in specific areas, and compared with soil environment, there are few studies on remediation methods for water environment. Therefore, we systematically reviewed the current situation of herbicide pollution in global coastal waters and the dose-response relationships of various herbicides on phytoplankton and higher trophic organisms from the perspective of ecological risks. In addition, we believe that compared with the traditional single physical and chemical remediation methods, biological remediation and its combined technology are the most promising methods for herbicide pollution remediation currently. Therefore, we focus on the application prospects, challenges, and management strategies of new bioremediation systems related to biology, such as constructed wetlands, membrane bioreactor processes, and microbial co-metabolism, in order to provide more advanced methods for reducing herbicide pollution in the water environment.

Interacting with luteinizing hormone receptor provides a new elucidation of the mechanism of anti-androgenicity of bisphenol S.

Bisphenol S (BPS) exhibited inhibitory effects on androgen synthesis, but its target of action remains unclear. We investigated the effects of BPS exposure at environmentally relevant concentrations (1 µg/L, 10 µg/L and 100 µg/L) for 48 h on androgen synthesis in rat ovarian theca cells and explored the underlying mechanisms, target site and target molecule. The results showed that BPS exposure inhibited the transcript levels of steroidogenic genes and reduced the contents of androgen precursors, testosterone and dihydrotestosterone. BPS exposure decreased the phosphorylation levels of extracellular signal-related kinase 1/2 (ERK1/2), and the inhibitory effects of BPS on testosterone content and steroidogenic gene expression were blocked by ERK1/2 agonist LY2828360, suggesting that ERK1/2 signaling pathway mediates the inhibitory effects of BPS on androgen synthesis. BPS mainly accumulated on the cell membrane, impermeable BPS-bovine serum albumin exposure still inhibited androgen synthesis, BPS interacted with rat luteinizing hormone receptor (LHR) via formation of hydrogen bonds in the transmembrane region, and the inhibitory effects of BPS on ERK1/2 phosphorylation were blocked by luteinizing hormone (the natural agonist of LHR), indicating that LHR located on the cell membrane is the target of action of BPS. This paper provides a new elucidation of the mechanism of anti-androgenicity of BPS, especially for the non-genomic pathways.

Bisphenol S remodels red blood cell membrane lipids by altering plasma lipid levels, causing the risk of venous thrombosis in SD rats and zebrafish embryos.

Bisphenol S (BPS) is a raw material that is used extensively in various manufacturing processes but possesses a high detection rate in human red blood cells (RBCs). Accordingly, BPS is a potential toxicant in disturbing the function of RBCs and causing RBC-related diseases. To date, the effects and mechanisms of BPS-induced RBC-related diseases have not been elucidated. Here, using different models, including rats, zebrafish embryos and RBCs, the underlying mechanism of RBC-related diseases induced by BPS was explored. The accumulation of BPS in tissue was colon > kidney > liver > plasma > testicle > heart > brain in SD rats orally administered BPS (10 and 50 mg/kg bw/day) for 32 days, which was similar in both 10 mg/kg bw/day and 50 mg/kg bw/day group. Rats given BPS orally developed hyperlipidemia and increased RBC membrane cholesterol, as well as changes in RBC morphology and function. Moreover, BPS at the concentrations measured in rats plasma caused oxidative stress and phosphatidylserine exposure in vitro RBCs. These combined factors led to RBC aggregation in blood and an increasing in the number of RBCs in the blood vessels of the liver in rats. The dynamic visual observation of RBCs in vein vessels of zebrafish embryos exposed to BPS at 0, 1, 10 and 100 µg/L further found that the flow of RBCs in the tail vein is slow or even immobile, posing the risk of venous thrombosis. The present study provides new insight into the links between environmental pollutants and venous thrombosis.

Continuous exposure to bisphenol S increases the accumulation of endogenous metabolic toxicants by obstructing the glucuronic acid pathway.

Uridine diphosphate glucuronic acid (UDPGA) is an essential substrate in the glucuronidation of exogenous and endogenous lipophilic compounds via the liver glucuronic acid pathway, and its synthesis depends on glucose and energy in the body. Bisphenol S (BPS), as a lipophilic environmental pollutant, has been widely utilized in the manufacturing of daily necessities. The biological effect of BPS in interference with liver energy metabolism might affect UDPGA synthesis and the excretion of lipophilic compounds, but this was not clearly revealed. Here, female zebrafish that were exposed to BPS for 35 days exhibited a significant decrease in UDPGA in the liver with significant accumulation of exogenous BPS and endogenous bilirubin in the body. One vital reason may be that the exposure to BPS for 35 days promoted the lipid formation through PPARg signaling and reduced energy levels in the liver, resulting in the decreased raw materials for UDPGA production in glucuronic acid pathway. Meanwhile, transcriptome analysis showed that BPS inhibited the mRNA expression levels of genes related to the glucuronic acid pathway. The accumulation of endogenous and exogenous lipophilic compounds can trigger a variety of toxicological effect. Thus, weakened liver detoxification might be the primary cause of the toxicological effects of lipophilic pollutants.

17ß-Trenbolone activates androgen receptor, upregulates transforming growth factor beta/bone morphogenetic protein and Wnt signaling pathways, and induces masculinization of caudal and anal fins in female guppies (Poecilia reticulata).

Sexually mature female guppies (Poecilia reticulata) were exposed to environmentally relevant concentrations (20, 200, and 2000 ng/L) of 17ß-trenbolone for four weeks. As evidenced by the increased caudal fin index and anal fins developing into gonopodium-like structures, exposed females displayed masculinized secondary sexual characteristics. Differential gene expression and subsequent pathway analysis of mRNA sequencing data revealed that the transcription of transforming growth factor beta/bone morphogenetic protein signaling pathway and Wnt signaling pathway were upregulated following 17ß-trenbolone exposure. Enzyme-linked immunosorbent assays showed that the bone morphogenetic protein 7 protein content was elevated after 17ß-trenbolone exposure. Finally, real-time PCR revealed that 17ß-trenbolone treatment significantly increased androgen receptor mRNA levels, and molecular docking showed potent interaction between 17ß-trenbolone and guppy androgen receptor. Furthermore, 17ß-trenbolone-induced masculinization of caudal and anal fins in female guppies, concomitant to the upregulated expression of differentially expressed genes involved in the above-mentioned two signaling pathways, was significantly inhibited by flutamide (androgen receptor antagonist). These findings demonstrated that 17ß-trenbolone masculinized fins of female guppies by activating the androgen receptor. This study revealed that 17ß-trenbolone could upregulate signaling pathways related to fin growth and differentiation, and eventually cause caudal and anal fin masculinization in female guppies.

Mechanism of thyroid hormone and its structurally similar contaminant bisphenol S exposure on retinoid metabolism in zebrafish larval eyes.

The photoreceptor necessitates the retinoids metabolism processes in visual cycle pathway to regenerate visual pigments and sustain vision. Bisphenol S (BPS), with similar structure of thyroid hormone (TH), was reported to impair the light-sensing function of zebrafish larvae via disturbing TH-thyroid hormone receptor ß (TRß) signaling pathway. However, it remains unknown whether TRß could modulate the toxicity of BPS on retinoid metabolism in visual cycle. This study showed that BPS diminished the optokinetic response of zebrafish larvae and had a stimulative effect on all-trans-retinoic acid (atRA) metabolism, like exogenous T3 exposure. By modulating CYP26A1 and TRß expression, it was found that CYP26A1 played a crucial role in catalyzing oxidative metabolism of atRA and retinoids regeneration in visual cycle, and TRß mediated cyp26a1 expression in zebrafish eyes. Similar with 10 nM T3 treatment, cyp26a1 expression could be induced by BPS in the presence of TRß. Further, in CYP26A1 and TRß- deficient eyes, 100 µg/L BPS could no longer promote atRA metabolism, or decrease the all-trans-retinol and 11-cis retinal contents in visual cycle, demonstrating that BPS exposure disturbed CYP26A1-mediated visual retinoids metabolism via TRß. Overall, this study highlights the role of TRß in mediating the retinoids homeostasis disruption caused by BPS, and provides new clues for exploring molecular targets of visual toxicity under pollutants stress.

Highly sensitive lateral flow immunoassays based on Ag@Au nanoflowers with marine medaka (Oryzias melastigm) vitellogenin as a target analyte.

In order to improve the sensitivity of lateral flow immunoassays (LFIAs) for the detection of piscine vitellogenin (Vtg), a well-established biomarker for environmental estrogens, Au coated Ag nanoflowers (Ag@Au NFs) were used as labeling probes to develop a LFIA for marine medaka Vtg. The synthesized Ag@Au NFs with good monodispersity had an average diameter of 44.1 nm and absorbance peak of 524 nm. When the concentration of goat anti-mouse IgG and anti-Vtg polyclonal antibody (anti-Vtg PAbs) were 1.3 and 0.4 mg/mL, respectively, the detection range of the LFIA was 0.19-25 ng/mL, and the visual detection limit was 0.1 ng/mL, which was approximately 80 times lower than that of LFIAs based on other nanoparticles (Au NPs, Ag NPs, Au NFs, and FM). After evaluation of its specificity and robustness, the usefulness of Ag@Au NFs labeled LFIA was validated by measuring Vtg induction in the plasma of marine medaka exposed to bisphenol A, a weak estrogenic chemical. This highly sensitive lateral flow immunoassay could detect Vtg biomarker within 15 min without the need of expensive and complicated instruments, and thus offered an ultrasensitive and robust on-site detection method for estrogenic activity in field environment.