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The effects of (H 2 O) n ( n = 1-3) clusters on the HO 2 + NH 2 → NH 3 + 3 O 2 reaction have been investigated by employing high-level quantum chemical calculations with M06-2X and CCSD(T) theoretical methods, and canonical variational transition (CVT) state theory with small curvature tunneling (SCT) correction. The calculated results show that two kinds of reaction, HO 2 ⋯(H 2 O) n ( n = 1-3) + NH 2 and H 2 N⋯(H 2 O) n ( n = 1-3) + HO 2 , are involved in the (H 2 O) n ( n = 1-3) catalyzed HO 2 + NH 2 → NH 3 + 3 O 2 reaction. Due to the fact that HO 2 ⋯(H 2 O) n ( n = 1-3) complexes have much larger stabilization energies and much higher concentrations than the corresponding complexes of H 2 N⋯(H 2 O) n ( n = 1-3), the atmospheric relevance of the former reaction is more obvious with its effective rate constant of about 1-11 orders of magnitude faster than the corresponding latter reaction at 298 K. Meanwhile, due to the effective rate constant of the H 2 O⋯HO 2 + NH 2 reaction being respectively larger by 5-6 and 6-7 orders of magnitude than the corresponding reactions of HO 2 ⋯(H 2 O) 2 + NH 2 and HO 2 ⋯(H 2 O) 3 + NH 2 , the catalytic effect of (H 2 O) n ( n = 1-3) is mainly taken from the contribution of the water monomer. In addition, the enhancement factor of the water monomer is 10.06-13.30% within the temperature range of 275-320 K, which shows that at whole calculated temperatures, a positive water effect is obvious under atmospheric conditions., Competing Interests: The authors declare no conflicts of interest., (This journal is © The Royal Society of Chemistry.)

The adsorption of O2 on the Cu2O(111) surface at different coverages has been studied by spin-polarized density functional theory (DFT+U) calculations and atomic thermodynamics. It has been found that the dissociative O2 prefers to adsorb on the reconstructed Cu2O(111) surface at low coverages (1/4 to 1 monolayer), while totally dissociative and mixed molecular and dissociative O2 prefers to adsorb on the reconstructed Cu2O(111) surface thermodynamically at higher coverages (5/4 to 7/4 monolayers). More interesting is that the CuO film can be automatically formed on the Cu2O(111) surface that was induced by the surface reconstruction of the Cu2O(111) surface and adsorption of four dissociative O2 molecules (1 monolayer), which agrees well with the recent experimental results. Along higher coverages of O2 adsorption (5/4 to 7/4 monolayers), much stronger surface reconstruction and relaxation was found. The probability distribution of different single-O2 adsorbed states on the Cu2O(111) surface as a function of temperature was analyzed using a Boltzmann model. The adsorption mechanism of O2 on the Cu2O(111) surface was analyzed using the phase diagram and compared with other metal oxides.

In insects, juvenile hormone (JH) and the steroid hormone ecdysone have opposing effects on regulation of the larval-pupal transition. Although increasing evidence suggests that JH represses ecdysone biosynthesis during larval development, the mechanism underlying this repression is not well understood. Here, we demonstrate that the expression of the Krüppel homolog 1 (Kr-h1), a gene encoding a transcription factor that mediates JH signaling, in ecdysone-producing organ prothoracic gland (PG) represses ecdysone biosynthesis by directly inhibiting the transcription of steroidogenic enzymes in both Drosophila and Bombyx Application of a JH mimic on ex vivo cultured PGs from Drosophila and Bombyx larvae induces Kr-h1 expression and inhibits the transcription of steroidogenic enzymes. In addition, PG-specific knockdown of Drosophila Kr-h1 promotes-while overexpression hampers-ecdysone production and pupariation. We further find that Kr-h1 inhibits the transcription of steroidogenic enzymes by directly binding to their promoters to induce promoter DNA methylation. Finally, we show that Kr-h1 does not affect DNA replication in Drosophila PG cells and that the reduction of PG size mediated by Kr-h1 overexpression can be rescued by feeding ecdysone. Taken together, our data indicate direct and conserved Kr-h1 repression of insect ecdysone biosynthesis in response to JH stimulation, providing insights into mechanisms underlying the antagonistic roles of JH and ecdysone., Competing Interests: The authors declare no conflict of interest.

To study the catalytic effects of (H 2 O) n (n = 1-3), the mechanisms of the reaction HO 2 + HO → 3 O 2 + H 2 O without and with (H 2 O) n (n = 1-3) have been investigated theoretically at the CCSD(T)/aug-cc-pVTZ//M06-2X/aug-cc-pVTZ level of theory, coupled with rate constant calculations using the conventional transition state theory. Our results show that upon incorporation of (H 2 O) n (n = 1-3) into the channel of H 2 O + 3 O 2 formation, two different reactions, i.e. HO + HO 2 (H 2 O) n (n = 1-3) and HO 2 + HO(H 2 O) n (n = 1-3), have been observed, and these two reactions are competitive with each other. The catalytic effects of (H 2 O) n (n = 1-3) mainly arise from the contribution of a single water vapor molecule; this is because the effective rate constants with water are respectively larger by 2-3 and 3-4 orders of magnitude than those of the reactions with (H 2 O) 2 and (H 2 O) 3 . Furthermore, the catalytic effects of the water monomer mainly arise from the H 2 OHO 2 + HO reaction, and the enhancement factor of this reaction is obvious within the temperature range of 240.0-425.0 K, with the branching ratio (k'(RW)/k tot ) of 17.27-80.77%. Overall, the present results provide a new example of how water and water clusters catalyze gas phase reactions under atmospheric conditions.

The insect-specific transcription factor Broad-Complex (BR-C) is transcriptionally activated by the steroid 20-hydroxyecdysone (20E) and regulates the expression of many target genes involved in insect growth and development. However, although the transcriptional regulation of BR-C proteins has been well studied, how BR-C is regulated at post-transcription and -translation levels is poorly understood. To this end, using liquid chromatography-tandem mass spectrometry analysis, we identified residue Ser-186 as a phosphorylation site of BR-C in silkworm. Site-directed mutagenesis and treatment with specific kinase activators and inhibitors indicated that the Ser-186 residue in silkworm BR-C is phosphorylated by protein kinase A (PKA). Immunostaining assays disclosed that PKA-mediated phosphorylation of silkworm BR-C has no effect on its nuclear import. However, luciferase reporter analysis, electrophoretic mobility shift assays, and chromatin immunoprecipitation revealed that the PKA phosphorylation event suppresses the transcriptional activation of silkworm BR-C target genes and that this inhibition was caused by repression of BR-C binding to its DNA targets. Of note, both in vitro and ex vivo experiments disclosed that a continuous 20E signal inhibits the PKA-mediated BR-C phosphorylation and also the cAMP/PKA pathway, indicating that 20E's inhibitory effect on PKA-mediated phosphorylation of silkworm BR-C contributes to maintaining BR-C transcriptional activity. In conclusion, our findings indicate that PKA-mediated phosphorylation inhibits silkworm BR-C activity by interfering with its binding to DNA and that 20E signaling relieves PKA-mediated phosphorylation of BR-C, thereby maintaining its transcriptional activity., (© 2017 by The American Society for Biochemistry and Molecular Biology, Inc.)

Alcohol-induced liver injury (ALD) shows obvious metabolic disorders, categorized by a wide range of metabolite abnormalities. High-throughput metabolomics technology appears to be an appropriate solution. In this study, a urine metabolic profile was assessed using a UPLC-Q-TOF/HDMS (liquid chromatography coupled to high resolution mass spectrometry) approach to investigate the underlying molecular mechanisms of ALD and the therapeutic effect of geniposide. The endogenous low-molecular-weight metabolites in the mouse model of ALD were observed and 48 specific biomarkers were identified. Geniposide was found to have a regulatory effect on 32 of them. Furthermore, targeted analysis of biomarkers showed clear separation between the model and geniposide treatment group. Fifteen biomarkers with high contribution to group differentiation were screened out. Also, a comprehensive analysis of a significant disturbance of multiple metabolic pathways indicated that geniposide could modify abnormal metabolism due to ethanol exposure, during which disorders relating to amino acid metabolism and the oxidative stress state could be alleviated. At the same time, accessory examinations, including plasma biochemical indicators and liver tissue pathological analysis, showed similar results. It was suggested that geniposide was effective as a hepatoprotective agent against ethanol-induced liver damage by re-balancing a wide range of metabolic disorders.

In this article, the reaction mechanisms of H2S + (3)O2 formation by the HO2 + HS reaction without and with catalyst X (X = H2O, (H2O)2 and (H2O)3) have been investigated theoretically at the CCSD(T)/6-311++G(3df,2pd)//B3LYP/6-311+G(2df,2p) level of theory, coupled with rate constant calculations by using conventional transition state theory. Our results show that in the presence of catalyst X (X = H2O, (H2O)2 and (H2O)3) into the channel of H2S + (3)O2 formation, the reactions between the SH radical and HO2(H2O)n (n = 1-3) complexes are more favorable than the corresponding reactions of the HO2 radical with HS(H2O)n (n = 1-3) complexes due to the lower barrier of the former reactions and the higher concentrations of HO2(H2O)n (n = 1-3) complexes. Meanwhile, the catalytic effect of water, water dimers and water trimers is mainly taken from the contribution of a single water vapor molecule, since the total effective rate constant of HO2H2O + HS and H2OHO2 + HS reactions was, respectively, larger by 7-9 and 9-12 orders of magnitude than that of SH + HO2(H2O)2 and SH + HO2(H2O)3 reactions. Besides, the enhancement factor of water vapor is only 0.37% at 240 K, while at high temperatures, such as 425 K, the positive water vapor effect is enhanced up to 38.00%, indicating that at high temperatures the positive water effect is obvious under atmospheric conditions. Overall, these results show how water and water clusters catalyze the gas phase reactions under atmospheric conditions.

The effect of a single water molecule on the HO2 + NO2 hydrogen abstraction reaction has been investigated by employing B3LYP and CCSD(T) theoretical approaches with the aug-cc-pVTZ basis set. The reaction without water has three types of reaction channels on both singlet and triplet potential energy surfaces, depending on how the HO2 radical approaches NO2. These correspond to the formation of trans-HONO + O2, cis-HONO + O2 and HNO2 + O2. Our calculated results show that triplet reaction channels are favorable and their total rate constant, at 298 K, is 2.01 × 10(-15) cm(3) molecule(-1) s(-1), which is in good agreement with experimental values. A single water molecule affects each one of these triplet reaction channels in the three different reactions of H2O···HO2 + NO2, HO2···H2O + NO2 and NO2···H2O + HO2, depending on the way the water interacts. Interestingly, the water molecule in these reactions not only acts as a catalyst giving the same products as the naked reaction, but also as a reactant giving the product of HONO2 + H2O2. The total rate constant of the H2O···HO2 + NO2 reaction is estimated to be slower than the naked reaction by 6 orders of magnitude at 298 K. However, the total rate constants of the HO2···H2O + NO2 and NO2···H2O + HO2 reactions are faster than the naked reaction by 4 and 3 orders of magnitude at 298 K, respectively. Their total effective rate constant is predicted to be 1.2 times that of the corresponding total rate constant without water at 298 K, which is in agreement with the prediction reported by Li et al. (science, 2014, 344, 292-296).