Reconstitution of G1 cyclin ubiquitination with complexes containing SCFGrr1 and Rbx1

Control of cyclin levels is critical for proper cell cycle regulation. In yeast, the stability of the G1 cyclin Cln1 is controlled by phosphorylation-dependent ubiquitination. Here it is shown that this reaction can be reconstituted in vitro with an SCF E3 ubiquitin ligase complex. Phosphorylated Cln1 was ubiquitinated by SCF (Skp1-Cdc53-F-box protein) complexes containing the F-box protein Grr1, Rbx1, and the E2 Cdc34. Rbx1 promotes association of Cdc34 with Cdc53 and stimulates Cdc34 auto-ubiquitination in the context of Cdc53 or SCF complexes. Rbx1, which is also a component of the von Hippel-Lindau tumor suppressor complex, may define a previously unrecognized class of E3-associated proteins.     

cyclinD1在增生性瘢痕不同时期的表达及意义

目的：了解cyclinD1在增生性瘢痕形成过程中的作用。方法：应用免疫组织化SP法检测不同时期增生性瘢痕和正常皮肤组织成纤维细胞中cyclinD1的表达。结果：随着增生性瘢痕的发展．增生性瘢痕成纤维细胞中的cyclinD1表达呈由强至弱的变化;正常皮肤成纤维细胞中cyclinD1的表达呈阴性。结论：cyclinD1可能在增生性瘢痕形成的早期发挥重要作用。     

Systemic leukocyte-directed siRNA delivery revealing cyclin D1 as an anti-inflammatory target

Cyclin D1 (CyD1) is a pivotal cell cycle-regulatory molecule and a well-studied therapeutic target for cancer. Although CyD1 is also strongly up-regulated at sites of inflammation, its exact roles in this context remain uncharacterized. To address this question, we developed a strategy for selectively silencing CyD1 in leukocytes in vivo. Targeted stabilized nanoparticles (tsNPs) were loaded with CyD1-small interfering RNA (siRNA). Antibodies to beta(7) integrin (beta(7) I) were then used to target specific leukocyte subsets involved in gut inflammation. Systemic application of beta(7) I-tsNPs silenced CyD1 in leukocytes and reversed experimentally induced colitis in mice by suppressing leukocyte proliferation and T helper cell 1 cytokine expression. This study reveals CyD1 to be a potential anti-inflammatory target, and suggests that the application of similar modes of targeting by siRNA may be feasible in other therapeutic settings.     

稻谷陈化过程中维生素B1、B2变化的动力学研究

为进一步了解稻米在陈化过程中维生素营养品质的变化趋势，尽量减少其损失和改善粮食维生素营养品质，采用人工陈化法，对稻米陈化过程中维生素B1、B2含量变化的动力学特征进行了研究。结果表明，陈化过程中稻米维生素B1和维生素B2含量损失严重，以45℃储藏约150d，维生素B1含量损失为74％，维生素B2含量损失67％；在45℃时，维生素B1的酶催化反应速率方程为1／V=41．807／C 65．211；维生素B2的酶催化反应速率方程为1／V=58．523／C 33．751。维生素B2的解离速率是维生素B1的两倍。储藏温度是严重影响稻米维生素含量的因素之一。     

Phosphorylation-dependent ubiquitination of cyclin E by the SCFFbw7 ubiquitin ligase

Cyclin E binds and activates the cyclin-dependent kinase Cdk2 and catalyzes the transition from the G1 phase to the S phase of the cell cycle. The amount of cyclin E protein present in the cell is tightly controlled by ubiquitin-mediated proteolysis. Here we identify the ubiquitin ligase responsible for cyclin E ubiquitination as SCFFbw7 and demonstrate that it is functionally conserved in yeast, flies, and mammals. Fbw7 associates specifically with phosphorylated cyclin E, and SCFFbw7 catalyzes cyclin E ubiquitination in vitro. Depletion of Fbw7 leads to accumulation and stabilization of cyclin E in vivo in human and Drosophila melanogaster cells. Multiple F-box proteins contribute to cyclin E stability in yeast, suggesting an overlap in SCF E3 ligase specificity that allows combinatorial control of cyclin E degradation.     

食用型油葵B1品种试种初报

油蔡B1品种是适合春、夏两季种植的食用型油料品种 ,该品种出油率高 ,且富含亚油酸 ,有利于降低胆固醇、高血脂 ,是现代保健优质极品食用油。笔者通过免耕种植试验 ,总结出一套食用型油葵B1的栽培技术     

Unmasking electronic energy transfer of conjugated polymers by suppression of O(2) quenching

The photochemistry of poly[2-methoxy, 5-(2'-ethyl-hexyloxy)-p-phenylene-vinylene] (MEH-PPV) has been found to be highly dependent on the presence of O(2), which increases singlet exciton quenching dramatically. Spectroscopy on isolated single molecules of MEH-PPV in polycarbonate films that exclude O(2) reveals two distinct polymer conformations with fluorescence maxima near 555 and 580 nanometers wavelength, respectively. Time-resolved single-molecule data demonstrate that the 580-nanometer conformation exhibits a "landscape" for intramolecular electronic energy relaxation with a "funnel" that contains a 580-nanometer singlet exciton trap at the bottom. The exciton traps can be converted to exciton quenchers by reaction with O(2). Conformationally induced, directed-energy transfer is arguably a critical dynamical process that is responsible for many of the distinctive photophysical properties of conjugated polymers.     

维生素B1和B12对米氏凯伦藻增殖的影响

[目的]研究维生素B1、B12在米氏凯伦藻有毒赤潮爆发增殖过程中的作用。[方法]设置7个不同浓度的维生素B1与B12的K培养基培养米氏凯伦藻,通过定期浮游计数框计数与活体叶绿素荧光值的测定,研究不同浓度维生素B1、B12下,米氏凯伦藻细胞密度与叶绿素荧光值的变化情况。[结果]在维生素B1浓度低于0.312 5×10-5g/L时,对米氏凯伦藻细胞密度与单位细胞叶绿素荧光值有显著影响（P〈0.05）;维生素B12浓度变化对米氏凯伦藻细胞密度与单位细胞叶绿素荧光值影响不显著（P〉0.05）。[结论]维生素B1对米氏凯伦藻细胞增殖有显著影响,维生素B12对米氏凯伦藻种群增殖的影响不显著。     

伏马菌素B1单克隆抗体的制备及鉴定

 【目的】真菌毒素可导致严重的食品安全问题。本试验旨在制备可用于检测伏马菌素B1的特异性单克隆抗体。【方法】制备伏马菌素B1人工抗原,杂交瘤细胞法筛选杂交瘤细胞株制备腹水型单克隆抗体,并对其特性进行鉴定。【结果】筛选得到杂交瘤细胞株F3,分泌的单克隆抗体亚类为IgG1,轻链类型为κ链;10%变性聚丙烯酰胺凝胶电泳显示单抗蛋白重链分子质量约为50 kD,轻链分子质量约为25 kD;间接酶联免疫吸附法测定杂交瘤细胞F3细胞培养上清和腹水效价分别为1:3 200和1:51 200;亲和力常数为1.60×10-8 mol•L-1;IC50值可达3.589 ng•mL-1;对其它真菌毒素不存在交叉反应;免疫转印法鉴定抗体具有高特异性。【结论】本试验制备FB1单克隆抗体具有较好亲和力和高特异性,具有良好的应用价值。     

Pla a 1的抗原表位分析

[目的]预测Plaa1抗原的免疫原性及B细胞表位。[方法]联合运用多种方法预测Plaa1的二级结构并预测其表面特性,如亲水性、可塑性及抗原表位。[结果]该蛋白是一个分子量约19kDa,pI值约8．7,主要为α-螺旋的结构紧凑的球形蛋白。预测其亲水性区域：32-42,55—59,76—8,88—89,92-98,110-112,118-127,140—151,157—163;预测其可塑性区域．28—40,49—57,76—80,87-98,109-114,121—125,137-139,144—151,154—162;预测其蛋白质抗原表位区域：29-42,49-60,75-78,86—100,107-114,116—130,134—152,156—164;预测其转角结构区域：39-42,51,55,88—89。[结论]Plaa1抗原蛋白具有较强的免疫原性;其主要的抗原表位集中于29—42,49—60,86—100,而这些预测结果为进一步寻求梧桐花粉变态反应的防治方法提供了依据。     

不同碳素纳米材料对黄曲霉毒素B1的吸附

黄曲霉毒素B1(AFB1)对人体有较强的毒性,因此脱除食品中的AFB1具有重要意义.为了探究碳素纳米材料对AFB1的吸附机理,研究石墨、石墨烯、氧化石墨烯对AFB1的吸附,建立等温吸附曲线,进行吸附动力学、热力学分析,结合结构表征,探究其吸附过程,并用这3种碳素纳米材料脱除食品(食用醋、花生奶、花生油)中的AFB1.结...     

非1B/1R类型和1B/1R类型小麦K型雄性不育系比较研究

利用非 1B/ 1R类型小麦 K型不育系 KTSP3314A和 1B/ 1R类型小麦 K型不育系 K3314A,分别与10个普通小麦品种 (系 ) 2 5 9,36 6 5 ,TB90 2 ,F10 7,J18,R2 0 5 ,L783,5 0 3,3380和 78115杂交 ,测定和比较其恢复性、单倍体发生频率和主要农艺性状。结果表明 ,非 1B/ 1R类型小麦 K型不育系比 1B/ 1R类型小麦 K型不育系更易恢复 ;不育系本身不产生单倍体 ,其杂交种 F1 产生极少或不产生单倍体 ;农艺性状除了株高具有明显的优势外 ,其他均无不利的遗传效应。     

两类小麦雄性不育系花粉发育中丙二醛含量及膜透性变化研究

利用1B/1R类型小麦不育系K3314A及保持系3314B与非1B/1R类型小麦不育系KTSP3314A及保持系TSP3314B,对其减数分裂时期、单核期、二核期、三核期、散粉成熟期五个时期的花粉细胞中丙二醛的含量以及膜透性的变化进行比较研究。结果表明:1B/1R和非1B/1R类型小麦不育系、保持系的丙二醛含量、电导率值变化基本相同,都呈上升趋势,曲线在单核期到三核期变化明显,且两类型的不育系均高于保持系;两类不育系电导率值变化略有不同,1B/1R类型不育系的电导率值在单核期、三核期、散粉成熟期高于非1B/1R类型小麦;两类型小麦雄性不育系花粉败育的时期是一致的,花粉败育的关键时期可能为单核期到三核期。