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The pericyclases are a growing superfamily of enzymes that catalyze pericyclic reactions. We report a pericyclase IccD catalyzing an inverse-electron demand Diels-Alder (IEDDA) reaction with a rate acceleration of 3 × 10 5 -fold in the biosynthesis of fungal natural product ilicicolin H. We demonstrate IccD is highly periselective toward the IEDDA cycloaddition over a competing normal electron demand Diels-Alder (NEDDA) reaction from an ambimodal transition state. A predicted flavoenzyme IccE was identified to epimerize the IEDDA product 8- epi-ilicicolin H to ilicicolin H, a step that is critical for the observed antifungal activity of ilicicolin H. Our results reveal the ilicicolin H biosynthetic pathway and add to the collection of pericyclic reactions that are catalyzed by pericyclases.

Ranking among the most effective anticancer drugs, anthracyclines represent an important family of aromatic polyketides generated by type II polyketide synthases (PKSs). After formation of polyketide cores, the post-PKS tailoring modifications endow the scaffold with various structural diversities and biological activities. Here we demonstrate an unprecedented four-enzyme-participated hydroxyl regioisomerization process involved in the biosynthesis of kosinostatin. First, KstA15 and KstA16 function together to catalyze a cryptic hydroxylation of the 4-hydroxyl-anthraquinone core, yielding a 1,4-dihydroxyl product, which undergoes a chemically challenging asymmetric reduction-dearomatization subsequently acted by KstA11; then, KstA10 catalyzes a region-specific reduction concomitant with dehydration to afford the 1-hydroxyl anthraquinone. Remarkably, the shunt product identifications of both hydroxylation and reduction-dehydration reactions, the crystal structure of KstA11 with bound substrate and cofactor, and isotope incorporation experiments reveal mechanistic insights into the redox dearomatization and rearomatization steps. These findings provide a distinguished tailoring paradigm for type II PKS engineering.

The first Trypsin from porcine pancreas catalyzed a novel one-pot three-component reaction of α-bromoketone, primary alkylamines, and phenylisothiocyanate for the synthesis of thiazole-imine derivatives with high yields (up to 98%) in a short time under mild conditions. The results revealed that Trypsin exhibited excellent catalytic activity and great tolerance for broad substrates. This Trypsin-catalyzed three component convergent method provides a novel strategy for the synthesis of thiazole-2-imine derivatives and expands the promiscuous functions of enzymes in organic synthesis., (Copyright © 2016 Elsevier B.V. All rights reserved.)

Postpartum estrogen withdrawal is known to be a particularly vulnerable time for depressive symptoms. Ovariectomized adult mice (OVX-mice) treated with hormone-simulated pregnancy (HSP mice) followed by a subsequent estradiol benzoate (EB) withdrawal (EW mice) exhibited depression- and anxiety-like behaviors, as assessed by forced swim, tail suspension and elevated plus-maze, while HSP mice, OVX mice or EB-treated OVX mice (OVX/EB mice) did not. The survival and neurite growth of newborn neurons in hippocampal dentate gyrus were examined on day 5 after EW. Compared with controls, the numbers of 28-day-old BrdU(+) and BrdU(+)/NeuN(+) cells were increased in HSP mice but significantly decreased in EW mice; the numbers of 10-day-old BrdU(+) cells were increased in HSP mice and OVX/EB mice; and the density of DCX(+) fibers was reduced in EW mice and OVX mice. The phosphorylation of hippocampal NMDA receptor (NMDAr) NR2B subunit or Src was increased in HSP mice but decreased in EW mice. NMDAr agonist NMDA prevented the loss of 28-day-old BrdU(+) cells and the depression- and anxiety-like behaviors in EW mice. NR2B inhibitor Ro25-6981 or Src inhibitor dasatinib caused depression- and anxiety-like behaviors in HSP mice with the reduction of 28-day-old BrdU(+) cells. The hippocampal BDNF levels were reduced in EW mice and OVX mice. TrkB receptor inhibitor K252a reduced the density of DCX(+) fibers in HSP mice without the reduction of 28-day-old BrdU(+) cells, or the production of affective disorder. Collectively, these results indicate that postpartum estrogen withdrawal impairs hippocampal neurogenesis in mice that show depression- and anxiety-like behaviors., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

Objective: The volatile components of the Hui formula "Ha Hei Lili" were extracted by steam distillation extraction (SD) and supercritical CO2 fluid extraction, and the structures were analyzed and identified by GC-MS., Methods: The GC-MS conditions were set as follows: Rxi-5Sil MS quartz capillary column (30 m x 0.25 mm, 0.25 μm), the initial temperature of 50 degrees C to keep 1 min, to 10 degrees C/min heating to 120 degrees C, maintained 3 min, then to 3 degrees C/min heating to 200 degrees C, maintained 3 min, and then to 5 degreesC/min heating to 290 degrees C, maintained until completion of analysis; helium as the carrier gas, column flow rate 1.0 ml/min, split ratio 25: 1, inlet temperature 250 degrees C, EI ionization source 70 eV, ion source temperature 230 degrees C, scan range of m/z 35 - 500., Results: Yield of volatile oil were 0.21% and 5.44% extracted by SD and SFE methods, respectively; and for SD method, 36 kinds of compounds were identified, accounted for 87.02% of total mass of volatile oil; for SFE method, 38 kinds of constituents were identified, accounted for 97.47% of total mass of volatile oil., Conclusion: The type of constituents contained in the volatile oil extracted by SD and SFE methods are totally different; and GC-MS can be used to identify the structures and relative content of volatile components, the results of this study can provide an experimental basis for development and utilization of Hui formula "Ha Hei Lili".

Objective: To investigate the prevalence of depressive symptom and its influencing factors among primary and middle school students in urban-rural-integrated area of Chongqing., Methods: A total of 3 013 primary and middle school students from an urban-rural-integrated area of Chongqing were selected by using multistage stratified cluster sampling method in this study. The general information, physical activities and physical examination conditions were investigated. Meanwhile, the depress symptoms were assessed by using children's depression inventory (CDI) and the incidence of adolescence related events were evaluated by using pubertal development scale (PDS). Chi-square test was used to analyze the detection rate of depression symptoms among different population and Logistic regression was used to analyse the influencing factors of depressive symptoms among primary and middle school students., Results: The detection rate of depressive symptoms was 20.1% (607/3013) totally, and it was gradually higher among the students with bad to good economic status (28.3%/18.4%/18.3%, chi2 = 28.415, P < 0.05). The students' detection rate of depression symptoms in different development level compared to companion by self image were 43.1%, 26.5%, 22.0% and 15.8% (chi2 = 79.621, P < 0.01). Among the senior school students, worse economic status, higher development level in self-evaluation, and no physical activities in a recent month (including physical training, aerobic exercise) were considered as the influencing factors of depressive symptoms., Conclusion: Focusing on the physical and mental health of growing children, establishing a good school environment and family environment, and strengthening physical activities will contribute to reducing the incidence of depressive symptoms.

Objective: Six1 and Six4 are expressed in several tumors, and associated with tumor progress and poor prognosis. The aim of this study was to investigate the expression of Six1 and Six4 in esophageal squamous cell carcinoma (ESCC), and to evaluate their correlation with the clinicopathological factors and prognosis., Methods: Tissue microarray technology and immunohistochemical method (EnVision) were used to detect the expression of Six1 and Six4 in the tumor tissues and corresponding adjacent normal epithelium of esophagus from 292 ESCC patients., Results: Among the 292 ESCC patients, the positive rates of Six1 and Six4 protein expression in tumor tissues were 72.9% (213/292) and 56.2% (164/292), respectively, significantly higher than the expression rate of 33.2% (97/292) and 32.5% (95/292) in adjacent normal epithelium of esophagus (P < 0.05). Chi square test showed that the expression of Six1 protein was related to tumor size, depth of tumor invasion and patient survival status; higher Six4 protein expression level was related to poor differentiation and increased depth of invasion. Single factor Log-rank analysis revealed that gender, TNM stage, Six1 protein expression level were related to the overall survival of ESCC patients (P < 0.05), while the five-year survival rate was significantly higher in the Six1-negative group than the Six1-positive group [51.9% (41/79) vs. 43.7% (93/213)]. Multi-factor Cox proportional risk model analysis showed that TNM stage and positive expression of Six1 were independent prognostic factors for ESCC patients (P < 0.05)., Conclusions: Six1 and Six4 are highly expressed in ESCC. Their expression levels are closely related to the progress and prognosis of ESCC. Over-expression of Six1 is related to poor prognosis in ESCC patients. Thus, Six1 could be used as an important prognostic indicator for ESCC patients.

Kosinostatin (KST), an antitumor antibiotic, features a pyrrolopyrrole moiety spirally jointed to a five-membered ring of an anthraquinone framework glycosylated with a γ-branched octose. By a combination of in silico analysis, genetic characterization, biochemical assay, and precursor feeding experiments, a biosynthetic pathway for KST was proposed, which revealed (1) the pyrrolopyrrole moiety originates from nicotinic acid and ribose, (2) the bicyclic amidine is constructed by a process similar to the tryptophan biosynthetic pathway, and (3) a discrete adenylation enzyme and a peptidyl carrier protein (PCP) are responsible for producing a PCP-tethered building block parallel to type II polyketide synthase (PKS) rather than for the PKS priming step by providing the starter unit. These findings provide an opportunity to further explore the inexplicable enzymatic logic that governs the formation of pyrrolopyrrole moiety and the spirocyclic skeleton., (Copyright © 2013 Elsevier Ltd. All rights reserved.)

Background & Objective: P27 protein and cyclin E were negative cell cycle regulators. Until the present, the influence of P27 protein and cyclin E on progression of colon cancer was unclear. The aim of this study was to observe the expression features of P27 protein and cyclin E in the tissues of colon neoplasms, and to investigate the relationship between colon neoplasms and tumor special growth factor (TSGF)., Methods: Sixty-nine cases of samples included 23 normal tissues, 28 colon polyps (13 inflammatory polyps and 15 adenomatous polyps), and 18 colon carcinomas. The location and expression of P27 protein and cyclin E were determined using immunohistochemical method in all samples. These samples were diagnosed using formal pathological techniques simultaneously; the relationship between colon neoplasms and TSGF was also investigated., Results: The positive signal of P27 and cyclin E was found mainly in the cytoplasm and extracellular matrix of normal colon tissues, inflammatory polyps, and adenomatous polyps. Less amount of positive expression product of P27 protein and cyclin E was observed in colon carcinoma cells; and the positive signal was only located in the cytoplasm of gland-like cells. The content of TSGF in colon carcinoma tissues was significantly higher than that in normal tissues (117.3+/-57.02 versus 64.16+/-27.5,P< 0.01), but there was no significant difference between colon carcinoma tissues and inflammatory polyp tissues (117.3+/-57.02 versus 92.5+/-47.9,P >0.05)., Conclusion: P27 protein and cyclin E participate in the adjustment process of colon neoplasm occurrence and progression. The reduced expression of P27 protein and cyclin E may indicate the possibility of colon carcinoma.