磷脂酰胆碱和TritonX-100对光系统Ⅱ蛋白二级结构及放氧活性影响的比较(英文)

采用傅立叶变换红外光谱技术 (FT_IR)和氧电极研究了磷脂酰胆碱和TritonX_10 0对光系统Ⅱ膜复合物的蛋白二级结构及放氧活性的影响。结果表明 ,磷脂酰胆碱对光系统Ⅱ膜复合物的蛋白二级结构没有显著的影响 ,但能引起放氧活性的提高 ,而且脂酰侧链长度不同 ,对放氧活性的促进程度也不一样。相比较而言 ,TX_10 0对膜脂的扰动却引起蛋白二级结构的明显改变 ,并能抑致放氧活性。结果说明 ,完整的膜结构对维持光合膜蛋白的稳定是非常重要的。     

高产小麦品种茎秆的解剖和化学特性

小麦(TriticumaestivumL.)新品种“小偃81”,是由抗病虫害小麦品种“小偃54”和高产小麦品种“8602”杂交筛选出的具有优良特性的后代。作者运用多种实验手段,研究了新品种茎秆组织结构以及木质素含量和分布的变化规律。结果表明:与母本“小偃54”和父本“8602”相比,“小偃81”的茎秆直径变小、横切面上维管束数目减少,而茎秆直径与壁厚比、横切面上机械组织比例却显著增大,单位面积上维管束数目增多。Klason法测定木质素结果显示:“小偃81”茎秆中木质素含量高于“小偃54”和“8602”。经Ma黮e和Wiesner的木质素显色反应,“小偃81”茎秆横切面染色明显加深。用H2O2/HAc弃除酚酸以后,新品种小麦的木质素自发荧光明显强于亲本。FTIR分析结果表明:“小偃81”中所含的紫丁香基、愈创木酚基等木质素特征基团的吸收峰值也显著高于亲本。由此推断,新品种“小偃81”的茎秆具有优良的组织结构和化学组成。     

针对不同基因靶位的锤头状核酶对HBV的抑制作用研究

前基因组mRNA是HBV(Hepatitis Bvirus)基因表达和复制的重要中间产物,全长的前基因组mRNA分子具有复杂易变的二级结构,是设计抑制HBV的核酶时所必须考虑的因素。我们使用多个最新的计算机软件对HBV前基因组mRNA二级结构进行模拟、分析,在全面分析核酶的可作用位点的基础上设计三个针对不同基因靶位的锤头状核酶,并对它们在细胞中对HBV的抑制作用进行研究。结果表明在HBV前基因组mRNA上存在几个高度复杂二级结构的区域,可能对核酶完全不敏感,而S、C、X基因的编码区是合适的核酶作用位点,都可达到对HBV的有效抑制,而且X基因位点的核酶对HBV的各种mRNA的抑制作用最为明显,是设计针对HBV核酶时应该优先考虑的位点。     

不同年代推出的冬小麦品种叶片气体交换日变化的差异

选择 6 0年来北京地区广泛种植的 3个冬小麦 (TriticumaestivumL .)品种 ,在相同的环境条件下种植。为了研究它们的产量与单位叶面积的净光合速率 (Pn)的关系 ,测定了不同生育期Pn、蒸腾速率 (Tr)的日变化 ,并用Pn/Tr计算叶片瞬时的水分利用率 (WUE)。结果表明 :单位叶面积净光合速率与产量之间的关系随生育期不同而变化。在拔节期高产品种“京冬 8号”(九十年代推出 )的光合速率和蒸腾速率在一天中总是最高 ,一天中差异最大时 ,分别比低产品种“燕大 1817”(四十年代推出 )高 77%和 6 9%。而其水分利用率却小于低产品种。这种差异随小麦的生长发育而变化 ,一般上午 10 :0 0前“京冬 8号”的光合速率较高 ,而 10 :0 0后“燕大 1817”的光合速率较高。到腊熟期 ,低产品种“燕大 1817”的光合速率在一天中始终最高。蒸腾速率的变化规律与光合速率相似 ,然而“燕大1817”叶片的水分利用率一般最高。与现代推出的品种不同 ,老品种“燕大 1817”叶片的光合作用午休现象不明显 ,说明它可能具有一定的抗光氧化性。我们认为 ,在品种改良的过程中 ,叶片光合作用的潜力可能有所提高 ,但它的抗光氧化性可能减弱。     

A Preliminary Study on the Introduction and Cultivation

Some species and culltivars of Clematis L.were introduced and cultivated.They were divided into three groups according to the different flower branch growth position.Seed propagation on Cl.ranunculoides showed the vernalized seeds sowed in soil had the best germination rate up to 71 percent.     

Changes in Soybean Raceme and Petiole Anatomy Induced by 6-Benzylaminopurine

An enlargement of the peduncle and rachis of the terminal racemeand the petiole of the uppermost mainstem leaf was observedin soybean plants [Glycine max (L.) Merr.] treated with thecytokinin, 6-benzylaminopurine (BAP). Histological studies wereperformed to determine the timing and extent of anatomical changesaccompanying BAP treatment. Swelling of treated ‘Tracy-M’peduncles, rachises, and petioles was observed within 4–6d after treatment initiation. A significant increase in totalcross-sectional tissue area was observed at lower and intermediateinternodes of treated rachises after 11 d. Rachis enlargementwas due to increases in both cell size and cell number, particularlyof the vascular tissue. In treated petioles of IX93-100, procambialcells of vascular bundles were the first to respond to the BAPtreatment. These cells differentiated into a vascular cambiumwhich formed secondary xylem and phloem. Soybean, Glycine max (L.) Merr., anatomy, rachis, BAP.     

视觉系统中的性别差异

大脑性别差异一直是神经科学领域中的一个热门话题.以前的性别差异研究往往关注与高级认知相关的脑区结构和功能差异,而对低级感知觉系统中的性别差异没有足够的重视.近年来,越来越多的研究结果表明,男性和女性在视知觉功能上也存在着明显的差异.本文首先回顾和梳理了视觉系统中存在性别差异的行为学和神经生物学证据,然后对视觉系统中性别...     

PERCEPTION OF FAT IN A MILK MODEL SYSTEM USING MULTIDIMENSIONAL SCALING

This study examined the contributions of stimulus fat content and flavor volatiles to the perception of fat in a milk model system. The model system was formulated by adding bland vegetable oil (0%, 5%, or 10% w/v) and natural cream flavor (0%, 0.5% or 1% w/v) to a skim milk base. Panelists judged pairs of samples for similarity on the basis of three attributes (fat content, mouthcoating and thickness) and the results were analyzed using a multidimensional scaling procedure. Two-dimensional solutions best represented the data. The stimulus spaces for fat content and mouthcoating were visually similar to each other and provided reasonable separation of the samples. Instrumental measures helped to define the underlying dimensions of the stimulus space for fat content. Dimension 1 related to texture and included the contributions of viscosity, and fat particle size and number distribution; dimension 2 related to flavor perception. The sample with a moderate fat content (5%) and the highest concentration of added cream flavor (1%) was perceived to be similar to the 10% fat samples with added flavor. Thus, the added flavor provided the sensation of higher fat content. These data suggest that flavor plays an important role in the preception of fat in dairy foods. A psychophysical model of fat perception in dairy foods is proposed which includes the contribution of viscosity, fat particle size and number distribution, and volatile flavor perceptions.