Characterization of natural rubber concerning its components and molecular weight in Taraxacum kok-saghyz Rodin using pyrolysis gas chromatography-mass spectrometry.

Taraxacum kok-saghyz Rodin (TKS) has abundant natural rubber in its root and the molecular weight of its natural rubber is higher than that in Hevea brasiliensis. Thus, TKS is an excellent alternative for the commercial production of natural rubber. The content and molecular weight of natural rubber are two qualitative indicators. Efficient determination for both indicators is still a challenge. In this study, we developed a method to simultaneously determine the content and molecular weight of natural rubber in TKS with pyrolysis－gas chromatography-mass spectrometry. The content of natural rubber was quantified by internal standard method. We optimized the pyrolysis temperature and chromatographic method during content determination. The limits of detection and quantification were 0.47 and 1.56 µg, respectively. In addition, the arachidonic acid methyl ester, an unsaturated fatty acid proposed from the α-end group of natural rubber, was quantified to obtain the number of natural rubber polymers. Based on the content and the polymer number, we also quantified the molecular weight of natural rubber. Thus, the content and molecular weight of natural rubber were simultaneously determined in TKS. Our study provides a new perspective for the high throughput analysis of natural rubber.

Genomic insight into domestication of rubber tree.

Understanding the genetic basis of rubber tree (Hevea brasiliensis) domestication is crucial for further improving natural rubber production to meet its increasing demand worldwide. Here we provide a high-quality H. brasiliensis genome assembly (1.58 Gb, contig N50 of 11.21 megabases), present a map of genome variations by resequencing 335 accessions and reveal domestication-related molecular signals and a major domestication trait, the higher number of laticifer rings. We further show that HbPSK5, encoding the small-peptide hormone phytosulfokine (PSK), is a key domestication gene and closely correlated with the major domestication trait. The transcriptional activation of HbPSK5 by myelocytomatosis (MYC) members links PSK signaling to jasmonates in regulating the laticifer differentiation in rubber tree. Heterologous overexpression of HbPSK5 in Russian dandelion (Taraxacum kok-saghyz) can increase rubber content by promoting laticifer formation. Our results provide an insight into target genes for improving rubber tree and accelerating the domestication of other rubber-producing plants.

Novel insights into the predominant factors affecting the bioavailability of polycyclic aromatic hydrocarbons in industrial contaminated areas using PLS-developed model.

Bioavailability is recognized as a useful technical standard for risk assessment and pollution rehabilitation. However, knowledge on the bioavailability of polycyclic aromatic hydrocarbons (PAHs) in contaminated site soils is still limited, especially concerning the influential mechanism. With an abundance of soil collections from nine industrial areas in China, the bioavailabilities, as conceptually defined as bioconcentration factors (BCFs) of PAHs were analyzed using biomimetic extraction of hydroxypropyl-ß-cyclodextrin (HPCD). Apart from the total content of PAHs varying with the different pyrogenic sources, the BCFs were greatly dependent on the soil physicochemical properties from the spatial scale and inversely proportional to the number of rings. Pearson correlation analysis indicated a weak relationship between bioavailability and the soil dissolved organic matter (DOM), pH and particle size. To incorporate the soil physicochemical properties and structural characteristics of PAHs determined by density functional theory (DFT), the optimum model for bioavailability was developed for BCFs by partial least square (PLS) analysis. The PLS-derived model was shown to be predictive within the applicability domain (AD). The structural characteristics, e.g., molecular polarizability and frontier orbital energy level that favor the soil adsorption of PAH isomers via dispersion interactions, and electron exchanges were indicated to be more impactful on bioavailability than soil environmental factors. However, soil factors should not be neglected, because the pH, DOM, etc. were significantly influential. It makes sense that the higher DOM causes greater bioavailability via increasing the free-dissolved fractions of PAHs. Interestingly, the effect of pH on bioavailability was spectrally validated by excitation-emission matrix (EEM) fluorescence, showing that the interaction between DOM and pyrene strengthened the fluorescence quenching of chromophores with the decline in pH.

Comparative evaluation and prioritization of key influences on biodegradation of 2,2',4,4'-tetrabrominated diphenyl ether by bacterial isolate B. xenovorans LB400.

Polybrominated diphenyl ethers (PBDEs) are a class of persistent organic pollutants being widely distributed and harmful to human health and wildlife, and the development of sustainable rehabilitation strategies including microbial degradation is of great concern. Although the increasing number of bacteria, especially the broad-spectrum and potent aerobes have been isolated for the efficient removal of PBDEs, the external influences and the corresponding influential mechanism on biodegradation are not fully understood yet. Given the wide-spectrum biodegradability of aerobic bacterial isolate, B. xenovorans LB400 for PBDEs, the dual impacts of many pivotal factors including pH, temperature, presence of dissolved organic matter (DOM) and cadmium ion etc. were comprehensively revealed on biodegradation of 2,2',4,4'-tetrabromodiphenyl ether (BDE-47). Due to the structural resemblance and stimulation of specific enzyme activity in bacteria, the biphenyl as substrates showed the greater capacity than non-aromatic compounds in improving biodegradation. The individual adaptation to neutrality and cultivation at about 30 °C was beneficial for biodegradation since the bacterial cellular viability and enzyme activity was mostly preserved. Although it was possibly good for the induction of hormesis and favorable to enhance the permeability or bioavailability of pollutant, the exceeding increase of Cd2+ or DOM may not give the profitable increase of biodegradation yet for the detrimental effect. For biodegradation, the mechanistic relationship that took account of the integrative correlation with the influential factors was artfully developed using partial least square (PLS) regression technique. Relative to the most significant influence of culture time and initial concentration of BDE-47, the larger relevance of other factors primarily marked as pH and DOM was consecutively shown after the quantitative prioritization. This may not only help understand the influential mechanism but provide a prioritizing regulation strategy for biodegradation of BDE-47. The PLS-derived relationship was validated with the certain predictability in biodegradation, and could be used as an alternative to accelerate a priori evaluation of suitability or improve the feasibility of such bacteria in remediation of PBDEs in the environment.

Congener-specificity, dioxygenation dependency and association with enzyme binding for biodegradation of polybrominated diphenyl ethers by typical aerobic bacteria: Experimental and theoretical studies.

Polybrominated diphenyl ethers (PBDEs) are a group of organic pollutants that have attracted much concerns of scientific community over the ubiquitous distribution, chemical persistence and toxicological risks in the environment. Though a great number of aerobic bacteria have been isolated for the rapid removal of PBDEs, the knowledge about biodegradation characteristics and mechanism is less provided yet. Herein, the congener-specificity of aerobic biodegradation of PBDEs by typical bacteria, i.e. B. xenovorans LB400 was identified with the different biodegradation kinetics, of which the changes were largely hinged on the bromination pattern. The more bromination isomerically at ortho-sites other than meta-sites or the single bromination at one of aromatic rings might always exert the positive effect. The biodegradation of PBDEs should be thermodynamically constrained to some extent because the calculated Gibbs free energy changes of initial dioxygenation by quantum chemical method increased with the increase of bromination. Within the transition state theory, the high correlativity between the apparent biodegradation rates and Gibbs free energy changes implied the predominance and rate-limiting character of initial dioxygenation, while the regioselectivity of dioxygenation at the ortho/meta-sites was also manifested for the more negative charge population. The molecular binding with the active domain of dioxygenase BphA1 in aerobe was firstly investigated using docking approach. As significantly illustrated with the positive relationship, the higher binding affinity with BphA1 should probably signify the more rapid biodegradation. Besides the edge-on π-π stacking of PBDEs with F227 or Y277 and π-cation formulation with histidines (H233, H239) in BphA1, the reticular hydrophobic contacts appeared as the major force to underpin the high binding affinity and rapid biodegradation of PBDEs. Overall, the experimental and theoretical results would not only help understand the aerobic biodegradation mechanism, but facilitate enhancing applicability or strategy development of engineering bacteria for bioremediation of PBDEs in the environment.

Major biotransformation of phthalic acid esters in Eisenia fetida: Mechanistic insights and association with catalytic enzymes and intestinal symbionts.

Phthalic acid esters (PAEs) are an important group of organic pollutants that are widely used as plasticizers in the environment. The PAEs in soil organisms are likely to be biotransformed into a variety of metabolites, and the combined toxicity of PAEs and their metabolites might be more serious than PAEs alone. However, there are only a few studies on PAE biotransformation by terrestrial animals, e.g. earthworms. Herein, the key biotransformation pathways of PAEs and their association with catalytic enzymes and intestinal symbionts in earthworms were studied using in vivo and in vitro incubation approaches. The widely distributed PAE in soil, dibutyl phthalate (DBP), was proven to be biotransformed rapidly together with apparent bioaccumulation in earthworms. The biotransformation of PAE congeners with medium or long side chains appeared to be faster compared with those with short side chains. DBP was biotransformed into butyl methyl phthalate (BMP), monobutyl phthalate (MBP), and phthalic acid (PA) through esterolysis and transesterification. Besides, the generation of small quantities of low-molecular weight metabolites via ß-oxidation, decarboxylation or ring-cleavage, was also observed, especially when the appropriate proportion of NADPH coenzyme was applied to transfer electrons for oxidases. Interestingly, the esterolysis of PAEs was mainly regulated by the cytoplasmic carboxylesterase (CarE) in earthworms, with a Michaelis constant (Km) of 0.416 mM in the catalysis of DBP. The stronger esterolysis in non-intestinal tissues indicated that the CarE was primarily secreted by non-intestinal tissues of earthworms. Additionally, the intestinal symbiotic bacteria of earthworms could respond to PAE stress, leading to the changes in their diversity and composition. The enrichment of some genera e.g. Bacillus and Paracoccus, and the enhancement of metabolism function, e.g. amino acids, energy, lipids biosynthesis and oxidase secretion, indicated their important role in the degradation of PAEs.

Mechanistic insights into primary biotransformation of diethyl phthalate in earthworm and significant SOD inhibitory effect of esterolytic products.

Phthalic acid esters (PAEs) are used as plasticizer or modifier in artificially-manufactured products. Though the rapid biotransformation of phthalates in microbes and plants have been well documented, it is less studied yet in terrestrial animals, e.g. earthworm. In this study, the major biotransformation of diethyl phthalate (DEP) in Eisenia fetida was illustrated using in vitro incubation of earthworm crude enzymes. DEP could be substantially biotransformed into phthalate monoester (MEP) and a small amount of phthalic acid (PA) through esterolysis, which was verified to be driven by endogenous carboxylesterase. Despite the inferior contribution, the oxidation of DEP might also occur under the initiated electron transfer by NADPH coenzyme. The dominant metabolite MEP showed a higher inhibition of superoxide dismutase (SOD) activity than DEP with EC50 of 0.0082 ± 0.0016 mmol/L, so the higher ecological risks of MEP would be marked. The inhibition effect of PA was validated to be even stronger than MEP though it was slightly generated. The direct binding interaction with SOD was proved to be an important molecular event for regulation of SOD activity. Besides the static quenching mechanism, the caused conformational changes including despiralization of α-helix and spatial reorientation of tryptophan were spectrally believed to affect binding and underlie inhibition efficiency of SOD activity.

Extensive sequence divergence between the reference genomes of Taraxacum kok-saghyz and Taraxacum mongolicum.

Plants belonging to the genus Taraxacum are widespread all over the world, which contain rubber-producing and non-rubber-producing species. However, the genomic basis underlying natural rubber (NR) biosynthesis still needs more investigation. Here, we presented high-quality genome assemblies of rubber-producing T. kok-saghyz TK1151 and non-rubber-producing T. mongolicum TM5. Comparative analyses uncovered a large number of genetic variations, including inversions, translocations, presence/absence variations, as well as considerable protein divergences between the two species. Two gene duplication events were found in these two Taraxacum species, including one common ancestral whole-genome triplication and one subsequent round of gene amplification. In genomes of both TK1151 and TM5, we identified the genes encoding for each step in the NR biosynthesis pathway and found that the SRPP and CPT gene families have experienced a more obvious expansion in TK1151 compared to TM5. This study will have large-ranging implications for the mechanism of NR biosynthesis and genetic improvement of NR-producing crops.

Structures of Foot-and-Mouth Disease Virus with Bovine Neutralizing Antibodies Reveal the Determinant of Intraserotype Cross-Neutralization.

Foot-and-mouth disease virus (FMDV) exhibits broad antigenic diversity with poor intraserotype cross-neutralizing activity. Studies of the determinant involved in this diversity are essential for the development of broadly protective vaccines. In this work, we isolated a bovine antibody, designated R55, that displays cross-reaction with both FMDV A/AF/72 (hereafter named FMDV-AAF) and FMDV A/WH/09 (hereafter named FMDV-AWH) but only has a neutralizing effect on FMDV-AWH. Near-atomic resolution structures of FMDV-AAF-R55 and FMDV-AWH-R55 show that R55 engages the capsids of both FMDV-AAF and FMDV-AWH near the icosahedral 3-fold axis and binds to the ßB and BC/HI-loops of VP2 and to the B-B knob of VP3. The common interaction residues are highly conserved, which is the major determinant for cross-reaction with both FMDV-AAF and FMDV-AWH. In addition, the cryo-EM structure of the FMDV-AWH-R55 complex also shows that R55 binds to VP3E70 located at the VP3 BC-loop in an adjacent pentamer, which enhances the acid and thermal stabilities of the viral capsid. This may prevent capsid dissociation and genome release into host cells, eventually leading to neutralization of the viral infection. In contrast, R55 binds only to the FMDV-AAF capsid within one pentamer due to the VP3E70G variation, which neither enhances capsid stability nor neutralizes FMDV-AAF infection. The VP3E70G mutation is the major determinant involved in the neutralizing differences between FMDV-AWH and FMDV-AAF. The crucial amino acid VP3E70 is a key component of the neutralizing epitopes, which may aid in the development of broadly protective vaccines. IMPORTANCE Foot-and-mouth disease virus (FMDV) causes a highly contagious and economically devastating disease in cloven-hoofed animals, and neutralizing antibodies play critical roles in the defense against viral infections. Here, we isolated a bovine antibody (R55) using the single B cell antibody isolation technique. Enzyme-linked immunosorbent assays (ELISA) and virus neutralization tests (VNT) showed that R55 displays cross-reactions with both FMDV-AWH and FMDV-AAF but only has a neutralizing effect on FMDV-AWH. Cryo-EM structures, fluorescence-based thermal stability assays and acid stability assays showed that R55 engages the capsid of FMDV-AWH near the icosahedral 3-fold axis and informs an interpentamer epitope, which overstabilizes virions to hinder capsid dissociation to release the genome, eventually leading to neutralization of viral infection. The crucial amino acid VP3E70 forms a key component of neutralizing epitopes, and the determination of the VP3E70G mutation involved in the neutralizing differences between FMDV-AWH and FMDV-AAF could aid in the development of broadly protective vaccines.

Mechanistic insight into hydroxylation of 2,2',4,4'-tetrabromodiphenyl ether during biodegradation by typical aerobic bacteria: Experimental and computational studies.

Polybrominated diphenyl ethers (PBDEs) are a group of persistent pollutants in the environment. Though aerobic biodegradation of PBDEs have been extensively studied, the involved hydroxylation mechanism decisive for whole biotransformation is not clear yet. During the effective biodegradation of 2,2',4,4'-tetrabromodiphenyl ether (BDE-47) by B. xenovorans LB400, the depletion of endogenous ∙OH by scavenger could bring about the significant decrease of biodegradation efficiency whereas ·O2- was nearly not influential. Given the importance of ∙OH in hydroxylation, the reaction mechanisms along major pathways of electrophilic addition and hydrogen abstraction were theoretically examined by density functional theory (DFT). For the less demand of activation energy, the relative preference of electrophilic addition was shown at aromatic C3-site. When the secondary reaction was considered after addition at C4-site, the barrierless association of ∙OH at C3-site and deprotonation by H2O was validated as the energetically-favorable pathway that may cause dihydroxylation of BDE-47 into 3,4-dihydroxyl-BDE-17. The electrophilic addition followed by seconary barrierless trans-association of ∙OH and then dehydration seemed favorable for monohydroxylation as regards energetic barrier merely up to 194.01 kJ mol-1, while the hydrogen abstraction by ∙OH from C5-site was more privileged actually. The theoretical insights would help well understand the hydroxylation mechanism of PBDEs by aerobes.

Impact of preimplantation genetic testing on obstetric and neonatal outcomes: a systematic review and meta-analysis.

OBJECTIVE: To investigate whether preimplantation genetic testing (PGT) increases the risk of adverse obstetric and neonatal outcomes. DESIGN: Systematic review and meta-analysis. SETTING: Not applicable. PATIENT(S): Pregnancies achieved after PGT or in vitro fertilization (IVF)/intracytoplasmic sperm injection (ICSI). INTERVENTION(S): Systematic search of databases until December 2020 with cross-checking of references from relevant articles in English. MAIN OUTCOME MEASURE(S): Obstetric and neonatal outcomes after PGT and IVF/ICSI, including mean birth weight, low birth weight, very low birth weight (VLBW), mean gestational age at birth, preterm birth, very preterm birth, birth defects, intrauterine growth retardation (IUGR), sex ratio, cesarean section, hypertensive disorders of pregnancy, gestational diabetes mellitus, placenta disorder (placenta previa, placenta abruption, placenta accreta), and preterm premature rupture of membranes. RESULT(S): Ultimately, a total of 785,445 participants were enrolled in this meta-analysis, and these participants were divided into a PGT group (n = 54,294) and an IVF/ICSI group (n = 731,151). The PGT pregnancies had lower rates of low birth weight (risk ratio [RR] 0.85, 95% confidence interval [CI] 0.75 to 0.98), VLBW (RR 0.52, 95% CI 0.33 to 0.81), and very preterm births (RR 0.55, 95% CI 0.42 to 0.70) than those of IVF/ICSI pregnancies. However, the PGT group had a higher rate of the obstetric outcome of hypertensive disorders of pregnancy (RR 1.30, 95% CI 1.08 to 1.57). The PGT did not increase the risk of other adverse obstetric and neonatal outcomes, such as those associated with mean birth weight, mean gestational age at birth, birth defects, IUGR, sex ratio, cesarean section, gestational diabetes mellitus, placental disorder (placenta previa, placenta abruption, placenta accreta), or preterm premature rupture of membranes. We performed subgroup analysis with only blastocyst biopsies and found that PGT with blastocyst biopsies was associated with a lower rate of VLBW (RR 0.55, 95% CI 0.31 to 0.95). The PGT with blastocyst biopsies did not increase the risk of other adverse obstetric and neonatal outcomes. Additionally, we performed subgroup analysis with only frozen-thawed embryo transfer cycles, and we found that PGT pregnancies were associated with a lower rate of VLBW (RR 0.55, 95% CI 0.31 to 0.97), a lower rate of cesarean birth (RR 0.90, 95% CI 0.82 to 0.99), a higher rate of preterm birth (RR 1.10, 95% CI 1.02 to 1.18), and a higher rate of IUGR (RR 1.21, 95% CI 1.06 to 1.38) than those of IVF/ICSI pregnancies. The PGT with frozen-thawed embryo transfer did not increase the risk of other adverse obstetric and neonatal outcomes. CONCLUSION(S): The pooled analysis suggested that PGT did not increase the risk of adverse obstetric outcomes. The association between PGT and a higher risk of IUGR requires further investigation.

Study on active response of superoxide dismutase and relevant binding interaction with bioaccumulated phthalates and key metabolites in Eisenia fetida.

Phthalic acid esters (PAEs) are a group of widespread persistent organic pollutants in the environment. Though the harmful effect of PAEs including activity inhibition of superoxide dismutase (SOD) to arouse oxidative stress were well documented, the deep insights into mechanisms that are relevant with SOD activity are still lacking. By 7d-cultivation of Eisenia fetida in artificially-polluted soil, the different active responses of SOD in earthworm were shown to PAE congeners. Despite the less bioaccumulation and bioavailability, the di-butyl phthalate (DBP) etc. structurally coupled with longer ester-chains appeared more effective to trigger the up-regulation and then the slight decline of SOD activity. Given the remarkable biotransformation especially for short-chain PAEs, the SOD activity response in earthworm should be regarded as joint effect with their metabolites, e.g. monophthalates (MAEs) and phthalic acid (PA). The in vitro SOD activity was shown with the obvious inhibition of 21.31% by DBP, 88.93% by MBP, and 58.57% by PA respectively when the concentrations were elevated up to 0.03 mM. The SOD activity inhibition confirmed the molecular binding with pollutants as an essential event besides the biological regulation for activity. The binding interaction was thermodynamically exothermic, spontaneous and strengthened primarily by Van der Waals force and hydrogen bonds, and was spectrally diagnosed with the conformational changes including diminution of α-helix content and spatial reorientation of fluorophore tryptophan. As coherently illustrated with the larger fluorescence quenching constants (3.65*104-4.47*104/mol) than DBP, the metabolites should be the priority concern due to stronger activity inhibition and toxicological risks.

Application and significance of PiCCO monitoring technique combined with troponin I detection in fluid resuscitation of elderly patients with septic myocardial dysfunction.

OBJECTIVE: This study was designed to demonstrate the predictive value of Pulse indicate Contour Cardiac Output (PiCCO) monitoring technique combined with troponin I (cTnI) detection in septic myocardial dysfunction (SMD) of the elderly. METHODS: One hundred and nineteen elderly patients with SMD treated in our hospital from March 2016 to September 2019 were enrolled and allocated into the joint group (JG; 64 cases) for capacity management of fluid resuscitation under the guidance of PiCCO monitoring technique and cTnI detection, and the control group (CG; 55 cases) for conventional capacity management. Clinical indicators, hemodynamics, improvement of myocardial injury markers and inflammatory factors 6 h and 36 h post intervention, fluid balance 6 h, 12 h and 36 h post intervention, drug consumption (norepinephrine), treatment effect and 28-day hospitalization mortality were compared between the two groups. RESULTS: After resuscitation, the urine volume per hour and the fluid resuscitation volume were higher while the blood lactic acid (BLA) expression was lower in JG as compared to CG. JG presented a remarkably lower central venous pressure (CVP) than CG after resuscitation, with notably higher mean arterial pressure (MAP) and central venous oxygen saturation (ScvO2). In comparison with CG, JG displayed dramatically lower cTnI and N-terminal pro-brain natriuretic peptide (NT-ProBNP) 6 h and 36 h post intervention, as well as evidently reduced interleukin-6 (IL-6), procalcitonin (PCT) and high-sensitivity C-reactive protein (hs-CRP). After 36 h of intervention, the fluid balance was evidently lower in JG than in CG. JG showed statistically less use of norepinephrine, less time of mechanical ventilation and ICU stay, and noticeably lower incidence of multiple organ dysfunction syndrome (MODS), as well as dramatically lower 28-day hospitalization mortality than CG post intervention. CONCLUSIONS: PiCCO monitoring technique combined with cTnI detection is high-performing in fluid resuscitation of elderly patients with SMD, which can meliorate the myocardial function of patients, reduce medication and facilitate disease recovery.

Understanding the role of bacterial cellular adsorption, accumulation and bioavailability regulation by biosurfactant in affecting biodegradation efficacy of polybrominated diphenyl ethers.

Microbiological degradation is often considered as an important strategy to reduce the risks of polybrominated diphenyl ethers (PBDEs), which are environmentally widespread and harmful to human health and wildlife. With the well-identified aerobic bacteria, i.e. B. xenovorans LB400, the biodegradation of 2,2',4,4'-tetrabrominated diphenyl ether (BDE-47) occurred efficiently in conformity to the first-order kinetics and showed the strong dependence on initial concentration of pollutant and bioavailability regulation by biosurfactant. The mild increase of initial concentration of BDE-47 would enhance biodegradation whereas the excessive increase failed due to the oxidative stress or cytotoxicity to bacteria. Rather than the bacterial extracellular adsorption that was bioactively-mediated in thermodynamics, the intracellular accumulations at different time gradients showed the negative correlation with biodegradation efficiency of BDE-47. The spontaneous biodegradation of pollutant should be sourced from the gradual reduction of intracellular accumulation. Though the improved bioavailability of BDE-47 by sucrose fatty acid ester (SFAE) hardly altered the extracellular adsorption, the bacterial intracellular accumulation was indicated to increase continuously with used amount of biosurfactant and then decrease for the cellular morphological damage, and interestingly it appeared to be temporary reservoir for prompt delivery to biodegradation in light of the opposite variation tendency with time.

Theoretical investigation of AhR binding property with relevant structural requirements for AhR-mediated toxicity of polybrominated diphenyl ethers.

Polybrominated diphenyl ethers (PBDEs) are more frequently suspected with the induction of toxicity via signal transduction pathway of cytosolic aryl hydrocarbon receptor (AhR), the initial binding to which is assumed to be an essential prerequisite during the ligand-dependent activation. However, the AhR binding property and associated toxicity of PBDEs is yet to be clearly known for lacking insights into the structural requirements at molecular level. To understand the AhR binding property of PBDEs, the ligand binding domain (LBD) of AhR was simulatively developed on homologous protein after basic validation of geometrical rationality and the binding interaction profile was visually described using molecular docking approach. For AhR binding, the offset or edge-on π-π stackings with aromatic motifs including Phe289, Phe345 and His285 were shown to be structurally required whereas the electrostatic attraction validated for AhR binding to dioxins might be less effective for 2,2',3,4,4'-pentabromodiphenyl ether (BDE-85). Besides the demands of less steric hindrance from alanines and weak formulation of hydrogen bonds, the dispersion force through large contact and polarization of S-π electrons seemed to be impactful when BDE-85 were closer to Cys327, Met334 or Met342. With theoretical computation of AhR binding energies, the more significant correlativity with bioassays was derived especially for the lowly/moderately brominated congeners, and could be used to predict the AhR binding affinity on certain degree. The informative results would thus not only help well understand the molecular basis of AhR-mediated toxicity but give an approach for accelerative evaluation of AhR binding and toxicity of PBDEs.

Expression of H19 imprinted gene in patients with repeated implantation failure during the window of implantation.

PURPOSE: To detect the expression level of imprinted gene H19 in the endometrium of patients with repeated implantation failure (RIF) who were undergoing in vitro fertilization and embryo transfer (IVF-ET) or frozen embryo transfer (FET). METHODS: Patients who underwent IVF/FET in Reproductive Medicine Center of Xiangya Hospital during April 1, 2015 to October 31, 2015 were chosen. The endometrium was collected from patients with repeated implantation failure during mid-luteal phase. Real-time quantitative reverse transcription PCR (qRT-PCR) and western blot were used to determine the expression of H19 lncRNA and integrin ß3 protein. Data analysis was performed using SPSS 19.0. RESULTS: When compared with the control group, decreased expression of H19 was detected in the RIF group (P = 0.04). The expression of integrin ß3 protein was also decreased in the RIF group compared to that in the control group (P = 0.04). The expression of H19 lncRNA was positively correlated with the expression of integrin ß3 protein (R = 0.477, P = 0.018). CONCLUSIONS: The expression of H19 lncRNA and integrin ß3 protein were down-regulated in the RIF patients.

[Risk factors for early miscarriage among intrauterine singleton pregnancies after treatment with in vitro fertilization/intracytoplasmic sperm injection].

OBJECTIVE: To investigate the risk factors associated with early miscarriage among intrauterine singleton pregnancies after treatment with in vitro fertilization (IVF)/intracytoplasmic sperm injection (ICSI).
 METHODS: A retrospective case-control study was performed on all singleton pregnancies underwent IVF/ICSI from January, 2013 to May, 2014, in Xiangya Hospital. Ninety-six early miscarriage patients served as a case group and 593 pregnancies with live birth served as a control group. We analyzed factors for early miscarriage after IVF/ICSI in two groups.
 RESULTS: Multivariate logistic regression analysis demonstrated that the women age, miscarriage history, and sperm DAN fragmentation index (DFI) were the risk factors for early miscarriage (P<0.05).
 CONCLUSION: Miscarriage after treatment with IVF/ICSI is affected by multiple factors. Women at elder age (>30 years old), women with a history of miscarriage or men with higher sperm DFI (≥15%) are the risk.