Preparation of subcooled liquid argon and test of its cooling ability.

Subcooled liquid nitrogen and nitrogen slush are often considered for high-speed cooling, but their preparation and maintenance are not easy. To address this issue, a unique device was designed to prepare subcooled liquid argon (SLA) using liquid nitrogen (LN). The cooling process was mathematically modeled to predict the preparation time. If the interlayer space between LN and liquid argon is filled with nitrogen gas, liquid argon could be cooled to 3.5 K subcooling within 1 h. If the interlayer is filled with air, 2 h are required to achieve the same subcooled state. An additional 1000 mL of LN was required for the preparation of 600 mL of 3.5 K SLA. The cooling tests of 3 µL microdroplets in 3 mm-6 mm capillary quartz tubes were duplicated to evaluate the potential of SLA. It was found that the cooling rate of microdroplet in the 3.5 K subcooled SLA is very close to that in the 3 K subcooled LN, higher than that in the saturated LN. The convenience of preparation and maintenance of SLA can make it good choice of cryogen for cryopreservation of biomaterials.

Decabromodiphenyl ethane affects embryonic development by interfering with nuclear F-actin in zygotes and leads to cognitive and social disorders in offspring mice.

Decabromodiphenyl ethane (DBDPE) is a novel retardant. DBDPE is used in various flammable consumer products such as electronics, building materials, textiles, and children's toys. The presence of DBDPE in humans makes it extremely urgent to assess the health effects of DBDPE exposure. Here, we used female mice as an animal model to investigate the effects of DBDPE on embryonic development and offspring health. The results showed that 50 µg/kg bw/day of DBDPE exposure did not affect spindle rotation in oocytes after fertilization, but led to a decrease of pronuclei (PN) in zygotes. Further investigation found that DBDPE interferes with the self-assembly of F-actin in PN, resulting in PN reduction, DNA damage, and reduced expression of zygotic genome activating genes, and finally leading to abnormal embryonic development. More importantly, we found that maternal DBDPE exposure did not affect the growth and development of the first generation of offspring (F1) mice, but resulted in behavioral defects in F1 mice. Female F1 mice from DBDPE-exposed mothers exhibited increased motor activity and deficits in social behavior. Both female and male F1 mice from DBDPE-exposed mothers exhibited cognitive memory impairment. These results suggest that DBDPE has developmental toxicity on embryos and has a cross-generational interference effect. It is suggested that people should pay attention to the reproductive toxicity of DBDPE. In addition, it also provides a reference for studying the origin of neurological diseases and indicates that adult diseases caused by environmental pollutants may have begun in the embryonic stage.

Modelling and experimental studies on mass transport of multiple cryoprotective agents in articular cartilage.

Cartilage transplantation is an effective way to repair, reconstruct, and replace damaged articular cartilage (AC) but its use is limited by the inability to preserve AC for long periods of time. Vitrification is an ideal choice for long-term storage of AC, and multiple cryoprotective agents (CPAs) with high concentration are usually used. To obtain high cell viability, chondrocytes at all locations inside AC should be protected properly by the CPAs during cooling and rewarming. Hence, it is important to know the mass transport properties of multiple CPAs as they synergistically infiltrate AC. In this study, a mathematical model to describe the mass transport behavior of multiple CPAs in AC was developed based on the mixture-averaged diffusion model. In addition, a methodology for the simultaneous determination of dimethyl sulfoxide, glycerol, ethylene glycol, and propylene glycol by carbon-13 nuclear magnetic resonance was established. The model is applicable for predicting single- and multiple-CPA permeation into AC, and its accuracy was verified by a massive experimental dataset. Simulation results showed reverse diffusion in the multiple-CPA permeation process, which was not found in the single-CPA permeation process. This curious phenomenon shows the sharp contrast between the diffusion behavior of a binary mixture and a multicomponent mixture.

Exposure of zebrafish embryos to sodium propionate disrupts circadian behavior and glucose metabolism-related development.

Sodium propionate is widely used as a preservative in food. The widespread use of preservatives is known to cause both environmental and public health problems. This study aimed to investigate the effects of sodium propionate on the developmental behavior and glucose metabolism of zebrafish. Our results showed that sodium propionate had no significant effect on the embryonic morphological development of zebrafish embryos but changed the head eye area. Then we found sodium propionate disturbed the thigmotaxis behavior, impaired neural development. Moreover, changes in clock gene expression disrupted the circadian rhythm of zebrafish. Circadian genes regulated insulin sensitivity and secretion in various tissues. Then our results showed that the disorder of circadian rhythm in zebrafish affected glucose metabolism and insulin resistance, which damaged the development of retina. Therefore, the safety of propionate should be further evaluated.

Exposure to Melamine cyanuric acid in adolescent mice caused emotional disorder and behavioral disorder.

Melamine cyanuric acid (MCA) is a flame retardant linked by hydrogen bonds between melamine and cyanuric acid. MCA is used in an excellent series of phosphorus and nitrogen flame retardants. MCA can harm the kidney, liver, testis, and spleen cells. However, the effects of MCA on the emotions and behaviour of adolescent mice have not yet been investigated. In this article, male mice were exposed to MCA at 10, 20, and 40 mg/kg for four weeks. MCA exposure resulted in enhanced mouse locomotor and nocturnal activity. We also observed anxiety-like and depression-like behaviours. Moreover, after MCA exposure, the serum concentrations of thyroid-related hormones were changed, and the mRNA levels were affected. In short, MCA exposure can cause behavioural and emotion disorders.

New doctor-patient communication learning software to help interns succeed in communication skills.

BACKGROUND: Nowadays, the research of doctor-patient communication is becoming increasingly important not only in China but also around the world. METHODS: The study designs a type of learning software to train the interns to advance their communication skills, and whose validity for improving doctor-patient communication in self-controlled trials is evaluated. With the aid of the new learning software, the self-controlled tests were carried out among 183 interns to assess the quality of their communication skill acquisition. The learning effectiveness of the preparation stage, information collection, information given, patient understanding, and inquisition ending was evaluated with the Set Elicit Give Understand End (SEGUE) framework after 3 months of training. RESULTS: More interns (37.16% vs. 10.98%, P < 0.001) could accurately identify the psychosocial or emotional factors contributing to the diseases. An increased number of interns (42.62% vs. 10.40%, P < 0.001) were able to openly discuss lifestyle issues and prevention strategies with patients. The study also revealed that interns who had completed training tended to allow patients more time to describe their feelings and concerns about their illnesses. In addition, more of the trained interns roved capable of being caring and respectful to patients and showing empathetic communication behavior (53.01% vs. 26.59%, P < 0.001). CONCLUSIONS: The doctor-patient communication software may help the interns known more about communication skills.

Fluorene-9-bisphenol exposure induces cytotoxicity in mouse oocytes and causes ovarian damage.

Fluorene-9-bisphenol (BHPF), a substitute for bisphenol A, is a chemical component of plastics for industrial production. There is evidence that BHPF exerts an antioestrogenic effect on mice, induces endometrial atrophy and leads to adverse pregnancy outcomes. However, the effects of BHPF on oocyte maturation and ovary development as well as its possible mechanisms remain unclear. The objective of this study was to investigate the toxicity and mechanism of BHPF exposure in mouse oocytes in vitro and in vivo. Our results showed that BHPF could inhibit the maturation of oocytes in vitro by reducing the protein level of p-MAPK and destroying the meiotic spindle. We found that in vitro, BHPF-treated oocytes showed increased ROS levels, DNA damage, mitochondrial dysfunction, and expression of apoptosis- and autophagy-related genes, such as Bax, cleaved-caspase 3, LC 3 and Atg 12. In addition, in vivo experiments showed that BHPF exposure could induce the expression of oxidative stress genes (Cat, Gpx 3 and Sod 2) and apoptosis genes (Bax, Bcl-2 and Cleaved-caspase 3) and increase the number of atresia follicles in the ovaries. Our data showed that BHPF exposure affected the first polar body extrusion of oocytes, increased oxidative stress, destroyed spindle assembly, caused DNA damage, altered mitochondrial membrane potentials, induced apoptosis and autophagy, and affected ovarian development.

Enhanced antitumor activity in A431 cells via encapsulation of 20(R)-ginsenoside Rg3 in PLGA nanoparticles.

OBJECTIVE: The objective of this study is to investigate the encapsulation of 20(R)-ginsenoside Rg3 (20(R)-Rg3) using polylactic-co-glycolic acid (PLGA) and promotion for its antitumor activity. SIGNIFICANCE: Preparation and evaluation of the antitumor efficacy of 20(R)-Rg3-loaded PLGA nanoparticles were the first reported. The data will be helpful to apply 20(R)-Rg3 efficiently and broadly in new drug form development and clinical cancer treatment. METHODS: The nanoparticles were prepared using emulsion and solvent evaporation methods. The uniform particle size and good dispersion were further confirmed by scanning electron microscopy. 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay was applied to detect cell proliferation after 20(R)-Rg3-loaded PLGA nanoparticles treatment. Western blotting and immunofluorescent staining were used for observation of key proteins related with proliferation and apoptosis. Cell cycle and apoptosis were analyzed by flow cytometer technology. RESULTS AND DISCUSSION: The results showed that the size of 20(R)-Rg3-loaded PLGA was 97.5 nm in diameter, and zeta potential was -28 mV detected by Malvern particle size analyzer. The encapsulation efficiency was 97.5%, and drug loading was 70.2% measured by high-performance liquid chromatography. The in vitro study showed that the encapsulated 20(R)-Rg3 was consecutively released and the release ratio reached to the highest value (19.36%) at the time point of 96 h. The encapsulated 20(R)-Rg3 significantly inhibited the proliferation and induced apoptosis in A431 cancer cells compared with the unencapsulated 20(R)-Rg3, control and PLGA alone. CONCLUSION: 20(R)-Rg3-loaded PLGA nanoparticles was well prepared and characterized. The antitumor activity was increased after PLGA encapsulation. The data will be beneficial to the development of new dosage forms of 20(R)-Rg3 and extensive application.

Enhanced isopropanol and n-butanol production by supplying exogenous acetic acid via co-culturing two clostridium strains from cassava bagasse hydrolysate.

The focus of this study was to produce isopropanol and butanol (IB) from dilute sulfuric acid treated cassava bagasse hydrolysate (SACBH), and improve IB production by co-culturing Clostridium beijerinckii (C. beijerinckii) with Clostridium tyrobutyricum (C. tyrobutyricum) in an immobilized-cell fermentation system. Concentrated SACBH could be converted to solvents efficiently by immobilized pure culture of C. beijerinckii. Considerable solvent concentrations of 6.19 g/L isopropanol and 12.32 g/L butanol were obtained from batch fermentation, and the total solvent yield and volumetric productivity were 0.42 g/g and 0.30 g/L/h, respectively. Furthermore, the concentrations of isopropanol and butanol increased to 7.63 and 13.26 g/L, respectively, under the immobilized co-culture conditions when concentrated SACBH was used as the carbon source. The concentrations of isopropanol and butanol from the immobilized co-culture fermentation were, respectively, 42.62 and 25.45 % higher than the production resulting from pure culture fermentation. The total solvent yield and volumetric productivity increased to 0.51 g/g and 0.44 g/L/h when co-culture conditions were utilized. Our results indicated that SACBH could be used as an economically favorable carbon source or substrate for IB production using immobilized fermentation. Additionally, IB production could be significantly improved by co-culture immobilization, which provides extracellular acetic acid to C. beijerinckii from C. tyrobutyricum. This study provided a technically feasible and cost-efficient way for IB production using cassava bagasse, which may be suitable for industrial solvent production.

Vapor pressures above the vitrified sucrose solution at low temperatures.

BACKGROUND: Vitrified solutions are encountered in food and biomaterial preservation. Data of the equilibrium water vapor pressure above the vitrified solution are scarce at temperatures below 0 degrees C. OBJECTIVE: The study measures the water vapor pressures above vitrified sucrose solutions. MATERIALS AND METHODS: Sucrose solutions with concentration ranging from 75% to 79% (wt) were vitrified by cooling in liquid nitrogen, and placed in a thermostat bath. Vapor pressure was measured with a high precision pressure gauge using static method. The vitrification of sucrose solution was verified with DSC. RESULTS: Experimental data were compared with two models. The empirical Zobrist model fits the experimental data well. The free volume model was improved by fitting the interaction parameter to experimental data. The average discrepancy could be reduced from 5.57% to 2.86%. CONCLUSION: The data have significant implications in the driving force of water removal in secondary drying process.

The active components of Erzhi wan and their anti-Alzheimer's disease mechanisms determined by an integrative approach of network pharmacology, bioinformatics, molecular docking, and molecular dynamics simulation.

Erzhi Wan (EZW), a classic Traditional Chinese Medicine formula, has shown promise as a potential therapeutic option for Alzheimer's disease (AD), yet its mechanism remains elusive. Herein, we employed an integrative in-silico approach to investigate the active components and their mechanisms against AD. We screened four active components with blood-brain barrier permeabilities from TCMSP, along with 307 corresponding targets predicted by SwissTargetPrediction, PharmMapper, and TCMbank websites. Then, we retrieved 2260 AD-related targets from Genecards, OMIM, and NCBI databases. Furthermore, we constructed the protein-protein interaction (PPI) network of the intersected targets via the STRING database and performed the GO and KEGG enrichment analyses using the "clusterProfiler" R package. The results showed that the intersected targets were intimately related to the p53/PI3K/Akt signaling pathway, serotonergic synapse, and response to oxygen level. Subsequently, 25 core targets were found differentially expressed in brain regions by bioinformatics analyses of GEO datasets of clinical samples from the Alzdata database. The binding sites and stabilities between the active components and the core targets were investigated by the molecular docking approach using Autodock 4.2.6 software, followed by pocket detection and druggability assessment via the DoGSiteScorer server. The results showed that acacetin, ß-sitosterol, and 3-O-acetyldammarenediol-II strongly interacted with the druggable pockets of AR, CASP8, POLB, and PREP. Eventually, the docking results were further cross-referenced with the literature research and validated by 100 ns of molecular dynamics simulations using GROMACS software. Binding free energies were calculated via MM/PBSA strategy combined with interaction entropy. The simulation results indicated stable bindings between four docking pairs including acacetin-AR, acacetin-CASP8, ß-sitosterol-POLB, and 3-O-acetyldammarenediol-II-PREP. Overall, our study demonstrated a theoretical basis for how three active components of EZW confer efficacy against AD. It provides a promising reference for subsequent research regarding drug discoveries and clinical applications.

A model for predicting the permeation of dimethyl sulfoxide into articular cartilage, and its application to the liquidus-tracking method.

Long-term storage of articular cartilage (AC) has excited great interest due to the practical surgical significance of this tissue. The liquidus-tracking (LT) method developed by Pegg et al. (2006) [29] for vitreous preservation of AC achieved reasonable survival of post-warming chondrocytes in situ, but the design of the entire procedure was more dependent on trial and error. Mathematical modeling would help to better understand the LT process, and thereby make possible improvements to attain higher cell survival. Mass transfer plays a dominant role in the LT process. In the present study, a diffusion model based on the free-volume theory and the Flory-Huggins thermodynamics theory was developed to predict the permeation of dimethyl sulfoxide (Me2SO) into AC. A comparison between the predicted mean concentration of Me2SO in the AC disc and the experimental data over wide temperature and concentration ranges [-30 to 37 °C, 10 to 64.5% (w/w)] shows that the developed model can accurately describe the permeation of Me2SO into AC [coefficient of determination (R(2)): 0.951-1.000, mean relative error (MRE): 0.8-12.8%]. With this model, the spatial and temporal distribution of Me2SO in the AC disc during a loading/unloading process can be obtained. Application of the model to Pegg et al.'s LT procedure revealed that the liquidus line is virtually not followed for the center part of the AC disc. The presently developed model will be a useful tool in the analysis and design of the LT method for vitreous preservation of AC.

Viscosities of the ternary solution dimethyl sulfoxide/water/sodium chloride at subzero temperatures and their application in cryopreservation.

Vitrification is considered as the most promising method for long-term storage of tissues and organs. An effective way to reduce the accompanied cryoprotectant (CPA) toxicity, during CPA addition/removal, is to operate at low temperatures. The permeation process of CPA into/out of biomaterials is affected by the viscosity of CPA solution, especially at low temperatures. The objective of the present study is to measure the viscosity of the ternary solution, dimethyl sulfoxide (Me2SO)/water/sodium chloride (NaCl), at low temperatures and in a wide range of concentrations. A rotary viscometer coupled with a low temperature thermostat bath was used. The measurement was carried out at temperatures from -10 to -50°C. The highest mass fraction of Me2SO was 75% (w/w) and the lowest mass fraction of Me2SO was the value that kept the solution unfrozen at the measurement temperature. The concentration of NaCl was kept as a constant [0.85% (w/w), the normal salt content of extracellular fluids]. The Williams-Landel-Ferry (WLF) model was employed to fit the obtained viscosity data. As an example, the effect of solution viscosity on modeling the permeation of Me2SO into articular cartilage was qualitatively analyzed.

Genomic characterization and seed transmission of a novel unclassified partitivirus infecting Polygonatum kingianum Coll. et Hemsl.

This study identified a novel virus in the family Partitiviridae infecting Polygonatum kingianum Coll. et Hemsl, which is tentatively named polygonatum kingianum cryptic virus 1 (PKCV1). PKCV1 genome has two RNA segments: dsRNA1 (1926 bp) has an open reading frame (ORF) encoding an RNA-dependent RNA polymerase (RdRp) of 581 amino acids (aa), and dsRNA2 (1721 bp) has an ORF encoding a capsid protein (CP) of 495 aa. The RdRp of PKCV1 shares 20.70-82.50% aa identity with known partitiviruses, and the CP of PKCV1 shares 10.70-70.80% aa identity with known partitiviruses. Moreover, PKCV1 phylogenetically clustered with unclassified members of the Partitiviridae family. Additionally, PKCV1 is common in P. kingianum planting regions and has a high infection rate in P. kingianum seeds.

[Progress with research on the permeability characteristics of reproductive cell membranes].

The successful cryopreservation of reproductive cells has important practical significance in many fields. In order to improve the recovery rate and viability of cryopreserved cells, it is necessary to study the permeability characteristics of cell membrane to both water and cryoprotectant. In this paper we review the studies on membrane permeability of animal reproductive cell for the recent years. We firstly list the typical permeability data of spermatozoa and oocyte membrane for water and cryoprotectant. We then analyze the effects of these characteristics on the design of cryopreservation protocol. We also introduce the latest experimental methods to measure the cell membrane permeability.

Effect of 17ß-trenbolone exposure during adolescence on the circadian rhythm in male mice.

The suprachiasmatic nucleus (SCN) is the main control area of the clock rhythm in the mammalian brain. It drives daily behaviours and rhythms by synchronizing or suppressing the oscillations of clock genes in peripheral tissue. It is an important brain tissue structure that affects rhythm stability. SCN has high plasticity and is easily affected by the external environment. In this experiment, we found that exposure to the endocrine disruptor 17ß-trenbolone (17ß-TBOH) affects the rhythmic function of SCN in the brains of adolescent male balb/c mice. Behavioural results showed that exposure to 17ß-TBOH disrupted daily activity-rest rhythms, reduced the robustness of endogenous rhythms, altered sleep-wake-related behaviours, and increased the stress to light stimulation. At the cellular level, exposure to 17ß-TBOH decreased the c-fos immune response of SCN neurons to the large phase shift, indicating that it affected the coupling ability of SCN neurons. At the molecular level, exposure to 17ß-TBOH interfered with the daily expression of hormones, changed the expression levels of the core clock genes and cell communication genes in the SCN, and affected the expression of wake-up genes in the hypothalamus. Finally, we observed the effect of exposure to 17ß-TBOH on energy metabolism. The results showed that 17ß-TBOH reduced the metabolic response and affected the metabolic function of the liver. This study revealed the influence of environmental endocrine disrupting chemicals (EDCs) on rhythms and metabolic disorders, and provides references for follow-up research.

Experimental study on the effect of the split-type air-conditioner on the transmission of smoking pollutants in a room.

Environmental tobacco smoke (ETS) has become one of the most important sources of indoor air pollution. The study aimed to obtain the variation characteristics of typical air pollutant concentrations when people smoke in a closed room and explore the effect of the air-conditioner. A closed and air-conditioned room of 21 m2 was taken as the research object. Fine particulate matter (PM2.5) and total volatile organic compound (TVOC) were measured while 10 cigarettes were burnt in smoldering or smoking mode, with the air-conditioner on or off. The contents of nicotine in condensate samples were obtained by liquid chromatography. The impact of ETS on indoor air quality lasted for hours, causing typical pollutant concentrations to far exceed the Chinese standard. The PM2.5 produced by smoking was 11 times higher than by smoldering, but the TVOC produced by smoldering was more than by smoking. After one hour of the cigarette burning off, the PM2.5 concentration would be decreased by 96.1% with the air-conditioner on, in contrast to 67.9% with the air-conditioner off. Nicotine was detected in all samples of condensate from the air-conditioner. It is concluded that smoking cigarettes cannot be replaced by smoldering to evaluate the pollution of ETS. The air-conditioner has a positive effect on reducing the concentration of air pollutants produced by cigarette burning. More than 10% of the indoor nicotine may be taken away by condensate discharge, and its possible pollution should be paid attention to.Implications: This study provides new evidence of the effect of the split-type air-conditioner on ETS. The TVOC concentrations, which were less considered previously, were measured. PM2.5 concentration in human breathing zone can be reduced more quickly with the air-conditioner on. This study shows that there is a big difference in the concentrations of typical pollutants between smoking and smoldering. And it could be a guide for the formulation of relevant research methods. This study also demonstrates that the air conditioning condensate from the smoking room may contain nicotine. Attention should be paid to the recovery and utilization of such condensate.

Network Pharmacology and Molecular Docking Analyses Unveil the Mechanisms of Yiguanjian Decoction against Parkinson's Disease from Inner/Outer Brain Perspective.

Objective: This study aims to explore the pharmacodynamic mechanism of Yiguanjian (YGJ) decoction against Parkinson's disease (PD) through integrating the central nervous (inner brain) and peripheral system (outer brain) relationship spectrum. Methods: The active components of YGJ were achieved from the TCMSP, TCMID, and TCM@Taiwan databases. The blood-brain barrier (BBB) permeability of the active components along with their corresponding targets was evaluated utilizing the existing website, namely, SwissADME and SwissTargetPrediction. The targets of PD were determined through database retrieval. The interaction network was constructed upon the STRING database, followed by the visualization using Cytoscape software. Then, we performed Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses on potential targets. Finally, the molecular docking approach was employed to assess the binding affinity between key components and key targets. Results: Overall, we identified 79 active components, 128 potential targets of YGJ, and 97 potential targets of YGJ-BBB potentially suitable for the treatment of PD. GO and KEGG analyses showed that the YGJ treatment of PD mainly relied on PI3K-Akt pathway while the YGJ-BBB was mostly involved in endocrine resistance. The molecular docking results displayed high affinity between multiple compounds and targets in accordance with previous observations. Conclusions: Our study unveiled the potential mechanisms of YGJ against PD from a systemic perspective: (1) for the YGJ, they have potential exerting effects on the peripheral system and inhibiting neuronal apoptosis through regulating the PI3K-Akt pathway; (2) for the YGJ-BBB, they can directly modulate endocrine resistance of the central nervous and holistically enhance body resistance to PD along with YGJ on PI3K-Akt pathway.

Low concentrations of the antidepressant venlafaxine affect courtship behaviour and alter serotonin and dopamine systems in zebrafish (Danio rerio).

Venlafaxine, a serotonin-noradrenaline reuptake inhibitor, is a widely used antidepressant drug routinely detected in aquatic environments. However, its potential impact on courtship behaviour in zebrafish is unknown. We tested the hypothesis that venlafaxine disrupts brain monoamine levels and molecular responses essential for courtship behaviour in zebrafish. Zebrafish (Danio rerio) were exposed to venlafaxine (1, 10, and 100 µg/L) for 20 days. We evaluated the molecular levels and neuronal basis of the effect of venlafaxine on courtship behaviour. Here, we show that venlafaxine inhibited courtship behaviour in zebrafish and increased the transcript levels of 5-ht1a and 5-ht2c while decreasing the transcript levels of genes involved in the dopaminergic system, including th1, th2, drd1b, and drd2b. Venlafaxine upregulated 5-HT levels and downregulated dopamine levels. Moreover, the subordinate fish from the venlafaxine-exposed group had significantly lower motor activity than the subordinate fish of the control group. Collectively, our results reveal that venlafaxine can disturb brain monoamine levels, affecting courtship behaviour in adult zebrafish.

Exogenous melatonin protects preimplantation embryo development from decabromodiphenyl ethane-induced circadian rhythm disorder and endogenous melatonin reduction.

Decabromodiphenyl ethane (DBDPE) is a novel flame retardant that is widely used in plastics, electronic products, building materials and textiles. Our previous studies have revealed the oocyte toxicity of DBDPE, but the effect of DBDPE on preimplantation embryo development has not been reported. Here, we investigated whether and how DBDPE exposure affects preimplantation embryo development. Adult female mice were orally exposed to DBDPE (0, 5, 50, 500 µg/kg bw/day) for 14 days. First, we found that after DBDPE exposure, mice showed obvious circadian rhythm disorder. Moreover, the development of preimplantation embryos was inhibited in DBDPE-exposed mice after pregnancy. Then, we further explored and revealed that DBDPE exposure reduced the endogenous melatonin (MLT) level during pregnancy, thereby inhibiting the development of preimplantation embryos. Furthermore, we discovered that exogenous MLT supplementation (15 mg/kg bw/day) rescued the inhibition of preimplantation embryo development induced by DBDPE, and a mechanistic study demonstrated that exogenous MLT inhibited the overexpression of ROS and DNA methylation at the 5-position of cytosine (5-mC) in DBDPE-exposed preimplantation embryos. Simultaneously, MLT ameliorated the DBDPE-induced mitochondrial dysfunction by increasing the mitochondrial membrane potential (MMP), ATP, and Trp1 expression. Additionally, MLT restored DBDPE-induced changes in zona pellucida (ZP) hardness and trophectoderm (TE) cortical tension. Finally, the protective effect of MLT on embryos ameliorated the adverse reproductive outcomes (dead fetus, fetus with abnormal liver, fetal weight loss) induced by DBDPE. Collectively, DBDPE induced preimplantation embryo damage leading to adverse reproductive outcomes, and MLT has emerged as a potential tool to rescue adverse reproductive outcomes induced by DBDPE.