香猪垂体特异性转录因子基因及其相关基因表达水平的半定量分析

采用RT-PCR方法对香猪及对照猪种(上海白猪、大约克夏猪)PIT-1基因和相关基因(GH、PRL和TSH-β基因)的mRNA扩增,并以β-actin为内参照进行基因表达水平的半定量分析。结果表明,香猪PIT-1基因及GH、TSH-β基因的表达水平均显著低于上海白猪和大约克夏猪(P<0.05),香猪与上海白猪、大约克夏猪在PRL基因表达水平上的差异也接近显著水平。研究结果提示,香猪的PIT-1基因可能存在着突变,从而使其PIT-1基因的表达水平降低,减弱了PIT-1蛋白对于GH、PRL及TSH-β基因转录和表达的激活功能,导致香猪生长缓慢和矮小性。     

介孔材料在基因工程中的应用

综述了介孔材料在基因工程方面的应用研究新进展，详述了近年来国外有关介孔分子筛材料在生物传感器、药物释放和输送、固定蛋白质酶等基因工程领域的研究情况，着重介绍了介孔分子筛在固定蛋白质酶方面的应用前景，展望了国内介孔分子筛在基因工程中的应用。     

Biochemical estimation of hepatitis B surface antigen in recombinant yeast

Purified recombinant hepatitis B surface antigen separated on polyacrylamide gels in the presence of sodium dodecyl sulphate has a very low staining index with Coomassie blue relative to a number of standard proteins. In contrast the protein stains better than average with silver nitrate. This property has been used to develop a semi-quantitative method of estimation of recombinant surface antigen in extracts of Saccharomyces cerevisiae producing this protein. The method can be used to follow purification protocols. It is quick, simple and since it measures the surface antigen biochemically, is independent of the aggregation state or conformation of the protein, a factor which can affect enzyme-linked immunoassays which rely on antigen-antibody interactions.     

垂直地震剖面的KIRCHHOFF积分偏移

把垂直地震剖面(VSP)资料转换到偏移距—深度域,可以通过 VSP CDP叠加来实现,也可用偏移技术来达到。但是,由于 VSP 为共炮点道集,所含数据量较少,所以用常规偏移方法很难获得良好的偏移效果。本文把传统的 Kirchhoff 积分算法推广到变速的叠前 VSP 资料偏移。要把Kirchhoff 积分算法用于 VSP 资料,其关键在于确定 Kirchhoff 轨迹,这相当于确定以源点和接收点为焦点的一等时轨迹。此轨迹与常规地面地震资料所用的常速 Kirchhoff 积分偏移形成的椭圆轨迹不同。本文采用射线方程来确定这种变速 Kirchhoff 轨迹。这种偏移方法的具体实现步骤和一般叠前偏移方法是一样的,主要包括成像时间的确定、近似的 Kirchhoff 积分记录波场外推和求和成像处理等内容。     

Cloning and sequencing of the URA3 gene of Kluyveromyces marxianus CBS 6556

The URA3 gene, coding for orotidine-5′-phosphate decarboxylase, from Kluyveromyces marxianus CBS 6556, was isolated from a genomic DNA library. The K. marxianus URA3 gene encodes a protein of 267 amino acids with a calculated molecular weight of 29·3 kDa. Comparison of the K. marxianus protein with the corresponding enzymes of Saccharomyces cerevisiae and Kluyveromyces lactis showed amino acid sequence identifies of 81% and 88%, respectively. Using contour-clamped homogeneous electric field gel electrophoresis, the genomic copy was found to be located on chromosome VI. We have used the cloned gene for the construction of a K. marxianus leu2 mutant. This mutant contains no heterologous sequences, which is essential to make it acceptable for application in the food industry.     

淀粉－丙烯腈接枝共聚物水解产物的非晶态X衍射表征函数

用不同方法制备了淀粉－丙烯腈接枝共聚物水解产物，测定了其Ｘ衍射曲线。用５种非晶态表征函数进行了理论计算，由Ｈｉｎｄｅｌｅｈ多项式得到最好结果。确定了Ｈｉｎｄｅｌｅｈ多项式的结构参数，并用此多项式进行了曲线拟合。     

基于小波变换和神经网络集成的人脸表情识别

提出了一种表情识别的新方法，首先通过基于小波变换的图像分解和K-L变换等处理，来抽取面部表情区域的有效鉴别特征．之后采用神经网络集成技术对六种典型表情进行识别。在CMU表情数据库上的实验表明，该方法达到了很高的识别率．而且对光照变化也有一定的不敏感性。     

Changes in phospholipase D experession in soybeans during seed development and germination

Activation of phospholipase D (PLD) has been linked to accumulation of nonhydratable phosphatides and lipid degradation leading to soybean seed deterioration during preharvest and postharvest events. This study examined the changes in PLD activity, protein, and mRNA in soybeans during seed development and germination. RNA blotting analysis indicated that expression of the gene that encodes PLD was highest during the early and middle stages of seed development. However, the amount of PLD activity accumulated per cotyledon reached the highest level in mature seeds. During germination and early seedling growth, PLD mRNA was not detected one day after imbibition, while a significant increase in PLD expression occurred in the cotyledons of three- and seven-day seedlings. Similarly, PLD activity and protein concentration showed little change during the first day of imbibition and increased afterward in three- and seven-day seedlings. These results suggested that expression of PLD is developmentally regulated and that the changes in its amount of activity and protein are controlled primarily at the mRNA level. Immunoblotting analysis further revealed the presence of PLD variants that were associated with specific stages of seed development and seedling growth. The PLD variants present in the cotyledons of mature seeds appeared to be distinct from those observed in the early stage of seed development and in young seedlings.     

What function for human lithostathine?: structural investigations by three-dimensional structure modeling and high-resolution NMR spectroscopy

Human lithostathine is a 144-residue protein, expressed in variousorgans and pathologies. Several biological functions have beenproposed for this protein. Among others, inhibition of nucleationand growth of CaCO₃ crystals in the pancreas and bacterial aggregationhas retained attention, because lithostathine presents highsequence similarities with calcium-dependent (or C-type) lectins.To study its structure-function relationship and compare itwith that of C-type lectins, we have built a model for lithostathine.This model is derived from the only two C-type lectins of knownstructures: rat mannose binding protein and human E-selectin.An original strategy, inspired by that proposed by Havel andSnow, was designed for model building. We have undertaken NMRstudies on the natural protein. Although complete structuredetermination has not yet been achieved, the NMR studies didconfirm the main characteristics of the model. From analysisof the proposed model, we concluded that lithostathine is notexpected to present sugar- or calcium-binding properties. Therefore,the mechanisms of bacterial aggregation and inhibition of CaCO₃nucleation and growth have not yet been elucidated.