Metabonomic and metallomic profiling in the amniotic fluid of malnourished pregnant rats

Epidemiology and studies in animal models have revealed that prenatal malnutrition is highly correlated with abnormal fetal neurodevelopment. We present here a combined metabonomic and metallomic profiling technique to associate the metabolic and trace-elemental composition variations of rat amniotic fluid (AF) in malnourished pregnant rats with the retardation of fetal rat neurodevelopment. The AF samples from three groups of pregnant Sprague-Dawley rats, which were fed either a normal diet, a low-protein diet, or "a famine diet", were subjected to GC/MS and ICP/MS combined with multivariate data analysis (MVDA). PCA scores plot of both GC/MS and ICP/MS data showed similar and unique metabolic signatures of AF in response to the different diets. Rats in the famine group released increased amounts of glycine, inositol, putrescine, and rubidium and decreased amounts of methionine, dopa, tryptophan, glutamine, zinc, cobalt, and selenium in the AF. These discriminable variations in the AF may indicate the abnormality of a number of metabolic pathways in fetal rats including the folate cycle and methionine pathway, the monoamine pathway, and tri-iodothyronine (T3) metabolism. The abnormalities may be the result of metabolites or elemental differences or a combination of both. This study demonstrates the potential of combining profiling of small-molecule metabolites and trace elements to broaden the understanding of biological variations associated with fetal neurodevelopment induced by environmental perturbation.     

Design and synthesis of novel 1-phenyl-3-(5-(pyrimidin-4-ylthio)-1,3,4-thiadiazol- 2-yl)urea derivatives with potent anti-CML activity throughout PI3K/AKT signaling pathway

In this investigation, a series of 1-phenyl-3-(5-(pyrimidin-4-ylthio)-1,3,4- thiadiazol-2-yl)urea receptor tyrosine kinase inhibitors were synthesized by a simple and efficient structure-based design. Structure-activity relationship (SAR) analysis of these compounds based on cellular assays led to the discovery of a number of compounds that showed potent activity against human chronic myeloid leukemia (CML) cell line K562, but very weak or no cellular toxicity through monitoring the growth kinetics of K562 cell during a period of 72 h using the real-time live-cell imaging. Among these compounds, 1-(5-((6-((3-morpholinopropyl) amino)pyrimidin-4-yl)thio)-1,3,4-thiadiazol-2-yl)-3-(4-(trifluoromethyl)phenyl)urea (7) exhibited the least cellular toxicity and better biological activity in cellular assays (K562, IC₅₀: 0.038 μM). Compound 7 also displayed very good induced-apoptosis effect for human CML cell line K562 and exerted its effect via a significantly reduced protein phosphorylation of PI3K/Akt signal pathway by Human phospho-kinase array analysis. In vitro results indicate that 1-phenyl-3-(5-(pyrimidin-4-ylthio)-1,3,4- thiadiazol-2-yl)urea derivatives are lead molecules for further development as treatment of chronic myeloid leukemia and cancer.     

Excess cholesterol inhibits glucose‐stimulated fusion pore dynamics in insulin exocytosis

Type 2 diabetes is caused by defects in both insulin sensitivity and insulin secretion. Glucose triggers insulin secretion by causing exocytosis of insulin granules from pancreatic β‐cells. High circulating cholesterol levels and a diminished capacity of serum to remove cholesterol from β‐cells are observed in diabetic individuals. Both of these effects can lead to cholesterol accumulation in β‐cells and contribute to β‐cell dysfunction. However, the molecular mechanisms by which cholesterol accumulation impairs β‐cell function remain largely unknown. Here, we used total internal reflection fluorescence microscopy to address, at the single‐granule level, the role of cholesterol in regulating fusion pore dynamics during insulin exocytosis. We focused particularly on the effects of cholesterol overload, which is relevant to type 2 diabetes. We show that excess cholesterol reduced the number of glucose‐stimulated fusion events, and modulated the proportion of full fusion and kiss‐and‐run fusion events. Analysis of single exocytic events revealed distinct fusion kinetics, with more clustered and compound exocytosis observed in cholesterol‐overloaded β‐cells. We provide evidence for the involvement of the GTPase dynamin, which is regulated in part by cholesterol‐induced phosphatidylinositol 4,5‐bisphosphate enrichment in the plasma membrane, in the switch between full fusion and kiss‐and‐run fusion. Characterization of insulin exocytosis offers insights into the role that elevated cholesterol may play in the development of type 2 diabetes.     

The apolipoprotein A‐I mimetic peptide,D‐4F,restrains neointimal formation through heme oxygenase‐1 up‐regulation

D‐4F, an apolipoprotein A‐I (apoA‐I) mimetic peptide, possesses distinctly anti‐atherogenic effects. However, the biological functions and mechanisms of D‐4F on the hyperplasia of vascular smooth muscle cells (VSMCs) remain unclear. This study aimed to determine its roles in the proliferation and migration of VSMCs. In vitro, D‐4F inhibited VSMC proliferation and migration induced by ox‐LDL in a dose‐dependent manner. D‐4F up‐regulated heme oxygenase‐1 (HO‐1) expression in VSMCs, and the PI3K/Akt/AMP‐activated protein kinase (AMPK) pathway was involved in these processes. HO‐1 down‐regulation with siRNA or inhibition with zinc protoporphyrin (Znpp) impaired the protective effects of D‐4F on the oxidative stress and the proliferation and migration of VSMCs. Moreover, down‐regulation of ATP‐binding cassette transporter A1 (ABCA1) abolished the activation of Akt and AMPK, the up‐regulation of HO‐1 and the anti‐oxidative effects of D‐4F. In vivo, D‐4F restrained neointimal formation and oxidative stress of carotid arteries in balloon‐injured Sprague Dawley rats. And inhibition of HO‐1 with Znpp decreased the inhibitory effects of D‐4F on neointimal formation and ROS production in arteries. In conclusion, D‐4F inhibited VSMC proliferation and migration in vitro and neointimal formation in vivo through HO‐1 up‐regulation, which provided a novel prophylactic and therapeutic strategy for anti‐restenosis of arteries.     

厌氧微生物降解多环芳烃研究进展

多环芳烃(PAHs)是一类普遍存在于环境介质中的难降解有机污染物,相对于好氧微生物降解PAHs的研究,厌氧微生物降解PAHs的研究则相对较少.本文从厌氧微生物降解PAHs的研究背景,厌氧降解微生物的特点和不同厌氧降解还原反应体系的角度综述了厌氧微生物降解PAHs的概况;结合厌氧微生物降解萘和菲转化途径的介绍,推断了其降解机制的内在原因;同时通过总结影响厌氧微生物降解PAHs的主要因素(包括:PAHs的生物可利用性、外源营养物质的添加、外源电子受体的添加、特定厌氧降解菌的筛选强化和部分环境因素等),指出了制约降解进程的潜在限制因子;并对厌氧微生物降解PAHs研究目前存在的问题和未来的发展方向作了简述与展望.     

银杏雌雄配子体发育及胚胎形成的研究进展

银杏（Ginkgo biloba）是现存最古老的裸子植物之一, 其生殖过程表现出许多原始特征和独特性状, 长期以来备受国内外专家的关注。经过近100年的研究取得了显著成果： （1） 银杏雄配子体发育周期长, 经历了从平周分裂到斜背式分裂,并最终垂周分裂形成带有鞭毛的游动精子; （2） 银杏雌配子体发育经历较长的游离核期和细胞化期, 分化形成颈卵器母细胞并经平周分裂、垂周分裂和斜向分裂形成成熟的颈卵器（包括有4个颈细胞和1个卵细胞）; （3） 推测其精细胞中的液泡状结构为受精过程中的遗传物质载体; （4） 原胚的形成经历了游离核期和细胞化期。该文针对国内外最新银杏生殖生物学方面的研究进展, 对银杏雌雄配子体发育、受精过程以及胚胎形成等方面进行较为系统全面的分析和总结, 为进一步的银杏生殖生物学研究提供有价值的参考资料。     

β-galactosidase-catalyzed synthesis of 3-O-β-D-galactopyranosyl-sn-glycerol: Optimization by response surface methodology

In this study, the synthesis of 3-O-β-D-galactopyranosyl-sn-glycerol (GG) was performed by the reverse hydrolysis of D-galactose and glycerol using β-galactosidase from Kluyveromyces lactis. Four process variables, reaction temperature (30.0–45.0?°C), reaction time (24–48?h), enzyme concentration (150.00–350.00?U/mL), and substrate molar ratio (glycerol:D-galactose, 7.5:12.5?mmol/mmol) were investigated and optimized via response surface methodology (RSM) for optimal GG synthesis. Both quadratic equations and the optimal reaction conditions were established. Results showed that the four variables, i.e., reaction temperature, reaction time, enzyme concentration, and substrate molar ratio had significant (p?β-galactosidase concentration and 8.65:1.00 of substrate molar concentration ratio (glycerol: D-galactose) at 39.8?°C and 48?h of reaction. Under these conditions, the GG concentration was 140.03?g/L and GG yield was 55.71%, which both were close to the predicted values (143.26?g/L and 56.73%). This finding proves the RSM to be a useful tool in optimizing process conditions for GG synthesis.     

Optimal secretion of alkali-tolerant xylanase in <Emphasis Type="Italic">Bacillus subtilis</Emphasis> by signal peptide screening

Xylanases are industrially important enzymes for xylan digestion. We experimentally screened over 114 Sec and 24 Tat pathway signal peptides, with two different promoters, for optimal production of an alkaline active xylanase (XynBYG) from Bacillus pumilus BYG in a Bacillus subtilis host. Though both promoters yielded highly consistent secretion levels (0.97 Pearson correlation coefficient), the Sec pathway was found to be more efficient than the Tat pathway for XynBYG secretion. Furthermore, the optimal signal peptide (phoB) for XynBYG secretion was found to be different from the optimal peptides for cutinase and esterase reported in previous studies. A partial least squares regression analysis further identified several statistically important variables: helical properties, amino acid composition bias, and the discrimination score in Signal P. These variables explain the observed 23 % variance in the secretion yield of XynBYG by the different signal peptides. The results also suggest that the helical propensity of a signal peptide plays a significant role in the beta-rich xylanase, but not in the helix-rich cutinase, suggesting a coupling of the conformations between the signal peptide and its cargo protein for optimal secretion.     

科尔沁沙质草地生物量积累过程对降水变化的响应模拟

科尔沁沙地是中国北方严重的沙漠化区域之一,理解其沙质草地生物量积累对降水变化的响应有利于该区域的生态恢复和后续经营管理。在植被-土壤水分耦合模型的基础上结合植被阈值-迟滞响应模式(T-D),在点尺度上模拟科尔沁沙质草地生长季植被生物量积累过程对降水变化的响应。结果表明(1)植被生物量积累对降水量变化表现出明显的非线性响应。降水量增加,促进植被生物量积累,反之则抑制生物量积累,但在同等程度的降水量变化下生物量积累对降水增加的响应远大于对降水量减少的响应。(2)生物量积累对降水频率变化的响应与单次有效降水量变化在干旱年和湿润年都显著正相关,但与累计有效降水量相关性微弱,而与有效降水间隔变化只在干旱年显著相关,表明在不同年份间降水频率变化实际上通过改变单次有效降水量和有效降水间隔来影响生物量的积累。(3)生物量积累过程对降水频率变化存在明显的响应阈值,但该阈值在不同的降水量和降水特征下并不相同。科尔沁沙质草地植被生物量积累过程对降水变化有明显的响应,植被-土壤水分耦合模拟与T-D模型的结合能有效地在日尺度上识别这种响应,这为探究植被和降水关系提供了新工具。