茶树中咖啡酰辅酶A氧甲基转移酶的基因克隆及其催化活性研究(英文)     

Yue ZHANG  Hai-peng LV  Cheng-ying MA  Li GUO  Jun-feng TAN  Qun-hua PENG  Zhi LIN 《Journal of Zhejiang University. Science. B》2015,16(2):103-112

目的:从茶树中克隆一种可以催化表没食子儿茶素没食子酸酯(EGCG)生成甲基化EGCG的酶——咖啡酰辅酶A氧甲基转移酶(CCo AOMT),实现甲基化EGCG的酶学合成,为甲基化EGCG的进一步开发利用提供理论依据和技术指导。创新点:本研究首次从茶树中克隆了一条CCo AOMT基因组序列;分析了CCo AOMT基因在不同茶树品种和不同成熟度茶鲜叶中的基因表达规律;证明了CCo AOMT具有催化合成甲基化EGCG的生物活性。方法:采用聚合酶链式反应(PCR)和序列分析获得CCo AOMT的编码序列和基因组序列;采用高效液相色谱-四级杆-飞行时间串联质谱技术(HPLC-QTOF-MS)分析酶促反应生成的甲基化EGCG产物(图4);采用实时荧光定量PCR分析CCo AOMT基因的表达差异(图5)。结论:本研究从茶树中克隆了CCo AOMT基因的编码序列(738 bp)和基因组序列(2678 bp),明确了该基因具有4个内含子和5个外显子;揭示了CCo AOMT可以催化EGCG生成EGCG4"Me、EGCG3"Me和EGCG3’Me等多种甲基化产物;证明了CCo AOMT具有催化生成甲基化EGCG的活性;并发现该基因的表达量高低与茶鲜叶的成熟度呈正相关关系。  相似文献   

Effect of microcystin-LR on protein phosphatase 2A and its function in human amniotic epithelial cells     

Liang J  Li T  Zhang YL  Guo ZL  Xu LH 《Journal of Zhejiang University. Science. B》2011,12(12):951-960

Due to their toxicity, the increased distribution of microcystins (MCs) has become an important worldwide problem. MCs have been recognized as inhibitors of protein phosphatase 2A (PP2A) through their binding to the PP2A catalytic subunit. However, the exact mechanism of MC toxicity has not been elucidated, especially concerning the cellular response and its autoregulation. To further dissect the role of PP2A in MC-induced toxicity, the present study was undertaken to determine the response of PP2A in human amniotic epithelial (FL) cells treated with microcystin-LR (MCLR), one of the MC congeners. The results show that a low-dose treatment of MCLR in FL cells for 6 h induced an increase in PP2A activity, and a high-dose treatment of MCLR for 24 h decreased the activity of PP2A, as expected. The increased mRNA and protein levels of the PP2A C subunit may explain the increased activity of PP2A. Furthermore, MCLR altered microtubule post-translational modifications through PP2A. These results further clarify the underlying mechanism how MCLR affects PP2A and may be helpful for elucidating the complex toxicity of MCLR.  相似文献   

��It depends on what science teacher you got��: urban science self-efficacy from teacher and student voices     

Virginia L. J. Bolshakova  Carla C. Johnson  Charlene M. Czerniak 《Cultural Studies of Science Education》2011,6(4):961-997

In the United States today, urban schools serve the majority of high-poverty and high minority populations including large numbers of Hispanic students. While many Hispanic students perform below grade level in middle school science, the science teaching community as a whole is lacking elements of diversity as teachers struggle to meet the needs of all learners. Researchers have recognized that science teacher effectiveness, one consequence of self-efficacy among teachers, is associated with future science achievement and science-related careers of their students. This qualitative study explores how three science teachers’ effectiveness in the classroom impacts students’ science self-efficacy beliefs at one urban middle school. Hispanic students were the focus of this investigation due to demographics and history of underperformance within this district. Teachers’ perspectives, as well as outside observer evaluations of instructional strategies and classroom climates were triangulated to explore dynamics that influence students’ interests and motivation to learn science using a framework to link teachers’ sense of efficacy (focusing on student outcomes). Findings suggest the impact teacher effectiveness can have on student outcomes, including strengthened student science self-efficacy and increased science achievement. Building awareness and support in teachers’ sense of efficacy, as well as developing respectful and supportive relationships between educator/facilitator and pupil during the transition to middle school may construct permanence and accomplishment for all in science.  相似文献   

Cloning and efficient expression of <Emphasis Type="Italic">Bacillus sp.</Emphasis> BH072 <Emphasis Type="Italic">tasA</Emphasis> gene in <Emphasis Type="Italic">Escherichia coli</Emphasis>     

韩烨  樊洁  周志江  檀茜倩  赵鑫 《天津大学学报(英文版)》2015,21(1):26-31

The Bacillus strain BH072 isolated from a honey sample showed strong antifungal activity against phytopathogen. Gene cloning test demonstrated that the strain had a tasA gene encoding an antifungal TasA protein. Although the wild strain simultaneously produced various antifungal substances, only the physicochemical property and antifungal activity of TasA protein were unclear due to the difficulty in extraction. In this study, tasA gene encoding the protein from Bacillus sp. BH072 was amplified by using the polymerase chain reaction (PCR) method and cloned into pET 28a (+) vector, and then expressed in host cells Escherichia coli BL21 (DE3). The expressed proteins were collected by centrifugation and ultrasonic treatment, and then purified by using nickel-nitrilotriacetic acid (Ni-NTA) metal affinity column and dialysis methods. The result of sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) test showed that an expected protein band appeared with a size of 31 kDa. The expressed products possessed antifungal activity against the phytopathogenic indicator strain Botrytis cinerea. A genetically engineered strain tasA of E. coli was established in this study which can efficiently express Tas A protein.  相似文献   

AtHsfAla 对拟南芥幼苗在干旱中生理指标的影响     

谭越  何承忠  郭丽红 《昆明师范高等专科学校学报》2015,(3)

以过量表达 AtHsfAla 及 AtHsfAla 基因沉默的转基因植株为材料,通过控制土壤水分进行干旱处理,结果显示,过量表达型干旱处理后的存活率最大,而基因沉默型最小,表明 AtHsfA1a 能增强植物的抗旱性。为了从生理水平研究 AtHsfA1a 提高抗旱性的机制,研究发现过量表达型的叶片相对含水量和叶绿素含量最高,而沉默型最低。不同基因型植株的 H2 O2和 MDA 的含量正好相反,说明 AtHsfA1a 通过保护细胞膜而减小细胞所受氧化伤害来提高抗旱能力。  相似文献   

浅析《澳大利亚高等教育残疾支持计划》     

施应娥  谭三红 《佳木斯教育学院学报》2015,(4):151

1990年,澳大利亚联邦政府把残疾人视为高等教育中的弱势群体,自此澳大利亚联邦政府开始制定政策来保障残疾人的高等教育入学机会。《澳大利亚残疾人支持计划》的目的就是保障该类群体的入学机会。本文通过分析的政策文本,政策实施,政策理念和特点来分析《高等教育残疾人》政策。  相似文献   

General University Requirements at Hong Kong Polytechnic University: evaluation findings based on student focus groups     

Daniel Tan Lei Shek  Florence Ka Yu Wu  Wen Yu Chai 《Assessment & Evaluation in Higher Education》2015,40(8):1017-1031

Under the new four-year undergraduate programme, a general education framework titled ‘General University Requirements’ (GUR) has been developed and implemented since 2012/2013 at Hong Kong Polytechnic University (PolyU). To evaluate the implementation and effectiveness of the GUR in its first year, focus group interviews with students were carried out. In 13 focus groups, 62 first-year students from eight faculties/schools who took GUR subjects in 2012/2013 academic year were interviewed by trained researchers. Results showed that students generally had good perceptions of the GUR in terms of the subject content, teaching methods and the overall effectiveness of the subjects. The interactive teaching and learning initiatives adopted in GUR subjects were particularly appreciated, although students expressed minor concerns on the administration of GUR subjects. The results suggest that the first-year implementation of the GUR at PolyU was generally smooth and successful from the perspectives of the students.  相似文献   

Innovating teacher education in a complex era     

Oon Seng Tan 《Educational Research for Policy and Practice》2015,14(3):193-200

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Changes in children’s anger,sadness, and persistence across blocked goals: Implications for self-regulation     

Lin Tan  Eunkyung Shin  Kenyon Page  Cynthia L. Smith 《Child development》2023,94(2):411-423

The current study took a person-centered approach to examine the heterogeneity of changes in children’s emotions and persistence during a goal-blocking task and examined how different profiles of emotions and persistence related to children’s self-regulation. Children’s anger, sadness, and persistence were rated in a goal-blocking task in toddlerhood (T1; N = 140, 72 boys, M_age = 2.67 years, 90.7% White) and preschool (T2). Children’s self-regulation, specifically sustained attention and engagement, was assessed at T1, T2, and early school-age (T3) from 2005 to 2012. Growth mixture modeling revealed two classes of children at T1 and three classes at T2 with different patterns of anger, sadness, and persistence. Children’s classification at T2, but not T1, significantly predicted their sustained attention and engagement both concurrently and longitudinally.  相似文献   

LD夜视成像探测中基于PSF的超分辨率重建技术研究     

谌雨章  谭海燕  杨婉璐 《科技广场》2014,(10)

夜视目标识别在视频监控中起着非常重要的作用。从早期的红外热成像发展至今,激光夜视成像系统被广泛的应用。它不仅受到大气吸收和散射特性的影响,还与光学系统中的透镜及传感器的衍射极限有关。在既有成本下,通过图像复原和超分辨率重建,可以尽可能的提高夜视成像的成像质量。很多学者的研究结果表明,成像系统的点扩散函数作为先验知识,可以提高图像复原的质量。因此,本文在最大后验概率框架下,实现点扩散函数与凸集投影超分辨率重建相结合,并应用到半导体激光夜视成像探测系统中,客观的图像质量评价标准被用来决定迭代次数。目标识别的实验结果表明,用本文提出的重建方法可以有效提高半导体激光夜视成像的范围和成像质量。  相似文献