多肽淀粉样沉积形成机制研究进展

淀粉样肽(amyloid peptide)是一类在一定条件下易于形成沉积的多肽或者蛋白质。这类多肽或者蛋白在一定的组织部位沉积引起的细胞毒性和细胞凋亡被认为是一些疾病的主要原因。尽管这类多肽在一级结构上没有明显的同源性,但它们形成的沉积具有共同的结构特征,即这些多肽形成了具有β片层结构的纤维状聚集体。淀粉样沉积的形成机制尚不清楚。研究认为,在沉积过程中,多肽分子首先形成寡聚体,然后转变为规则的β折叠结构,进而组装形成淀粉样纤维。很多因素有助于这一转变,如多肽序列、氨基酸残基间的相互作用,介质的疏水性、温度、pH以及金属离子的浓度等。对多肽淀粉样沉积形成机制的深入研究将为探索相关疾病病因和开发治疗药物提供极有价值的依据。     

TGF-β-induced PLEK2 promotes metastasis and chemoresistance in oesophageal squamous cell carcinoma by regulating LCN2

Oesophageal squamous cell carcinoma (ESCC) has a relatively unfavourable prognosis due to metastasis and chemoresistance. Our previous research established a comprehensive ESCC database ({"type":"entrez-geo","attrs":{"text":"GSE53625","term_id":"53625"}}GSE53625). After analysing data from TCGA database and {"type":"entrez-geo","attrs":{"text":"GSE53625","term_id":"53625"}}GSE53625, we found that PLEK2 predicted poor prognosis in ESCC. Moreover, PLEK2 expression was also related to the overall survival of ESCC patients undergoing chemotherapy. Repression of PLEK2 decreased the proliferation, migration, invasion and chemoresistance of ESCC cells in vitro and decreased tumorigenicity and distant metastasis in vivo. Mechanistically, luciferase reporter assay and chromatin immunoprecipitation assay suggested that TGF-β stimulated the process that Smad2/3 binds to the promoter sequences of PLEK2 and induced its expression. RNA-seq suggested LCN2 might a key molecular regulated by PLEK2. LCN2 overexpression in PLEK2 knockdown ESCC cells reversed the effects of decreased migration and invasion. In addition, TGF-β induced the expression of LCN2, but the effect disappeared when PLEK2 was knockdown. Moreover, AKT was phosphorylated in all regulatory processes. This study detected the major role of PLEK2 in driving metastasis and chemoresistance in ESCC by regulating LCN2, which indicates the potential use of PLEK2 as a biomarker to predict prognosis and as a therapeutic target for ESCC.Subject terms: Cancer, Molecular biology     

Inhibitory effect of D1-like and D3 dopamine receptors on norepinephrine-induced proliferation in vascular smooth muscle cells

The sympathetic nervous system plays an important role in the regulation of blood pressure. There is increasing evidence for positive and negative interactions between dopamine and adrenergic receptors; the activation of the alpha-adrenergic receptor induces vasoconstriction, whereas the activation of dopamine receptor induces vasorelaxation. We hypothesize that the D1-like receptor and/or D3 receptor also inhibit alpha1-adrenergic receptor-mediated proliferation in vascular smooth muscle cells (VSMCs). In this study, VSMC proliferation was determined by measuring [3H]thymidine incorporation, cell number, and uptake of 3-(4,5-dimethylthiazol-2-yl)-diphenyltetrazolium bromide (MTT). Norepinephrine increased VSMC number and MTT uptake, as well as [3H]thymidine incorporation via the alpha1-adrenergic receptor in aortic VSMCs from Sprague-Dawley rats. The proliferative effects of norepinephrine were attenuated by the activation of D1-like receptors or D3 receptors, although a D1-like receptor agonist, fenoldopam, and a D3 receptor agonist, PD-128907, by themselves, at low concentrations, had no effect on VSMC proliferation. Simultaneous stimulation of both D1-like and D3 receptors had an additive inhibitory effect. The inhibitory effect of D3 receptor was via protein kinase A, whereas the D1-like receptor effect was via protein kinase C-zeta. The interaction between alpha1-adrenergic and dopamine receptors, especially D1-like and D3 receptors in VSMCs, could be involved in the pathogenesis of hypertension.     

FACE水稻干物质积累与分配模型

借助中国唯一的FACE技术平台,通过设置不同的N肥处理,研究了FACE条件下水稻干物质积累及分配动态的模拟模型.模型以生理发育时间为驱动因子,以CO₂浓度函数为主要影响因子,同时引入N素影响因子调节干物质的积累与各器官分配指数.模拟结果表明,随着大气CO₂浓度的增加,水稻地上部总干物重显著增加,叶干重分配指数下降,穗干重分配指数基本不变,茎干重分配指数前期增加,后期持平.通过不同年份试验数据对模型的验证,预测根均方差（RMSE）较小,且相关系数均达到了极显著水平.表明模型拟合程度高,具有较好的适应性和预测性.     

FACE水稻茎蘖动态模型

借助农田开放式空气CO₂浓度增高（FACE）技术平台,以武香粳14为供试水稻品种,设置不同施N量处理,研究大气CO₂浓度为570 μmol·mol^-1（比对照高200 μmol·mol^-1）的FACE处理对水稻茎蘖动态的影响,并建立了相应的模拟模型：T_t=A₁(1+e^a1-b1t₎-A₂(1+e^a2-b2t)+C×[B₁(1+e^a3-b3t)-B₂(1+e^a4-b4t)]+D.模型以时间为驱动因子,描述了水稻茎蘖数随移栽天数的动态变化过程,对常规及CO₂浓度增加条件下水稻茎蘖的变化均有很好的拟合性.通过不同年份试验数据对模型的检验,预测根均方差（RMSE）最大为44.27个·m^-2,最小为13.96个·m^-2,且相关系数均达到了极显著水平.表明模型的预测程度较高,具有很好的适用性.     

白头叶猴栖息环境与栖息地选择的研究

通过样方法和焦点动物法分别对白头叶猴栖息环境进行了观察,并对栖息环境的植物多样性进行了统计分析。结果表明,白头叶猴栖息地可分为山脚、山腰、山顶和山弄平地4部分,各部分优势种植物不同,白头叶猴栖息地的Shannon Venner多样性指数为6.152,均匀度为0.8439,白头叶猴对石山山脚、山腰、山顶和山弄平地的利用率分布为66.45 5.65%,21.15±5.49%,12.78±6.8%。在山脚主要是休息和觅食,在山腰主要是移动,在山顶主要是冬季晒太阳。因此,保护白头叶猴的栖息地对保护白头叶猴有特别重要的意义。     

白头叶猴食谱与觅食时间分配的研究

白头叶猴生活在喀斯特石山环境 ,以树叶为食。对其进行跟踪观察表明白头叶猴有食物 42种 ,其中乔木占 42 .8% ,灌木占 2 6.1 % ,藤本占 2 1 .5% ,草本占 9.6% ,食物组成中树叶占63%— 95% ,果实占 5%— 35% ,花占 0— 6%。白头叶猴有两种觅食方式 ,每天猴群有觅食高峰 2次。白头叶猴觅食的持续时间占日活动时间分配的比例在一年中有季节性变化 ,表现为夏天低冬天高 ,分别为 1 0 .0 3% (6月份 )— 2 3.2 1 % (1 2月份 ) ,这与食物的丰盛状况有关。     

固定化脂肪酶有机相中催化己酸乙酯反应动力学研究

有机相中脂肪酶催化反应动力学研究是酶工程领域中一个引起广泛兴趣的研究课题［１］。目前的研究较多地集中于水解反应和转酯反应［２～４］。对于酯化反应的动力学报道不多。酶反应动力学研究对于研究反应机理、确定有效的酶促反应环境、选择合适的酶反应器有着十分重要的作用。因此,对非水相中脂肪酶催化反应动力学的研究无论在理论上还是在实际应用中都有着重要的意义。与自由酶相比,使用固定化酶可提高酶在有机相中的扩散效果和热力学稳定性,是调节控制酶活性常用的手段。但酶固定化以后,影响其动力学的因素增多,反应机制变得更加…     

Synthesis and characterization of biocompatible thermo-responsive gelators based on ABA triblock copolymers

The synthesis of biocompatible, thermo-responsive ABA triblock copolymers in which the outer A blocks comprise poly(N-isopropylacrylamide) and the central B block is poly(2-methacryloyloxyethyl phosphorylcholine) is achieved using atom transfer radical polymerization with a commercially available bifunctional initiator. These novel triblock copolymers are water-soluble in dilute aqueous solution at 20 degrees C and pH 7.4 but form free-standing physical gels at 37 degrees C due to hydrophobic interactions between the poly(N-isopropylacrylamide) blocks. This gelation is reversible, and the gels are believed to contain nanosized micellar domains; this suggests possible applications in drug delivery and tissue engineering.