Chromosomal localization of a unique gene by non-autoradiographic in situ hybridization

During the past few years, several methods have been developed for the detection of specific nucleic acid sequences by in situ hybridization using non-radioactive labels such as fluorochromes, cytochemically detectable enzymes and electron-dense markers. These methods are preferable to autoradiography in terms of speed of performance and topological resolution. Their limited sensitivity, however, has so far restricted their use to the detection of repeated sequences. Here we report single gene detection with a procedure using 2-acetylaminofluorene (AAF)-modified probes, immunoperoxidase cytochemistry and reflection-contrast microscopy. We confirmed the autoradiographic data on the localization of the human thyroglobulin (Tg) gene to the distal end of the long arm of chromosome 8. A mixture of cosmid cHT2-derived subclones of the 3' part of the Tg gene, 22.3 kilobase pairs (kbp) in total, was used as a hybridization probe. This procedure can be used to map other unique sequences, if genomic clones are available from which clones with an appropriate amount of inserts can be isolated.     

中性磷萃淋树脂吸附铼的性能和机理研究ⅢCL－P＿（350）－KReO＿4－HNO＿3体系

本文报道四甲基膦酸二甲庚酸萃淋树脂（ＣＬ－Ｐ＿（３５０）从硝酸溶液中吸附鳞的性能和机理研究。实验结果表明，吸附平衡服从Ｌａｎｇｍｕｉｒ经验等温式。测得吸附物分子中Ｐ（３５０）与Ｒｅ（Ⅶ）的摩尔比为２：１。Ｒｅ（Ⅶ）是以形式被树脂吸附，其吸附机理属于综合反应：并测定了吸附过程的热力学函数。     

一种改进的实信号IFFT算法

由于重量轻、体积小、功耗低、功能强的小卫星工作在无人干预的低温 ,高辐射的空间环境中 ,因此星上计算机系统必须满足集成度高、寿命长、可靠性高、抗辐射能力强的要求。针对立体测绘小卫星的特点 ,我们设计了满足上述要求的集集中控制与分布控制优点于一身的星上计算机系统 ,对其可靠性进行了分析 ,并对提高其可靠性应采取的关键技术进行了简要的论述。     

Acquired immunity and epidemiology of Schistosoma haematobium

Human immune responses to schistosome infection have been characterized in detail. But there has been controversy over the relative importance of ecological factors (variation in exposure to infection) and immunological factors (acquired immunity) in determining the relationships between levels of infection and age typically found in areas where infection is endemic. Independent effects of exposure and age on the rates of reinfection with Schistosoma haematobium after chemotherapy have been demonstrated in the Gambia and Zimbabwe. This age effect could be the result of acquired immunity to infection. Indeed, allowing for variation in exposure and age, low rates of reinfection in the Gambia are correlated with high amounts of specific IgE antibodies--human IgE can kill S. mansoni schistosomulae in vitro. Further, animals can acquire immunologically mediated resistance to S. mansoni infection, although nonimmunological factors could also be involved. Acquisition of this immunity seems to be related to the cumulative effects of repeated infection and provides only partial protection. These characteristics are consistent with immuno-epidemiological data for both S. mansoni and S. haematobium infections of humans. We have now analysed age-prevalence data for human infection with S. haematobium, and find patterns of variation that are indeed consistent with the epidemiological effects of acquired immunity predicted by mathematical models.     

Descartes’s changing mind

Descartes is always concerned about knowledge. However, the Galileo affair in 1633, the reactions to his Discourse on method, and later his need to reply to objections to his Meditations provoked crises in Descartes’s intellectual development the import of which has not been sufficiently recognized. These events are the major reasons why Descartes’s philosophical position concerning how we know and what we may know is radically different at the end of his life from what it was when he began. We call this later position Descartes’s epistemic stance and contrast it with his earlier methodological, metaphysical realism. Yet Descartes’s epistemic views cannot be separated from other aspects of his work, for example, his views concerning God, causality, metaphysics, and the nature of science. A further meta-implication is that serious errors await any scholar who cites early Cartesian texts in support of late Cartesian positions, or who uses later texts in conjunction with early ones to support a reading of Descartes’s philosophy.     

BP网络及其应用

基函数选取和系数求解是函数逼近中的两个关键问题,目前广泛应用的回归分析或其它映射方法均有局限性。采用人工神经网络中的BP网较好地解决了这两个问题,对理论和实际的数据进行了比较与验证,结果表明.BP网络有助于提高数据处理的可靠性与预测的精度.     

Mutation of the matrix metalloproteinase 2 gene (MMP2) causes a multicentric osteolysis and arthritis syndrome.

The inherited osteolyses or 'vanishing bone' syndromes are a group of rare disorders of unknown etiology characterized by destruction and resorption of affected bones. The multicentric osteolyses are notable for interphalangeal joint erosions that mimic severe juvenile rheumatoid arthritis (OMIMs 166300, 259600, 259610 and 277950). We recently described an autosomal recessive form of multicentric osteolysis with carpal and tarsal resorption, crippling arthritic changes, marked osteoporosis, palmar and plantar subcutaneous nodules and distinctive facies in a number of consanguineous Saudi Arabian families. We localized the disease gene to 16q12-21 by using members of these families for a genome-wide search for homozygous-by-descent microsatellite markers. Haplotype analysis narrowed the critical region to a 1.2-cM region that spans the gene encoding MMP-2 (gelatinase A, collagenase type IV; (ref. 3). We detected no MMP2 enzymatic activity in the serum or fibroblasts of affected family members. We identified two family-specific homoallelic MMP2 mutations: R101H and Y244X. The nonsense mutation effects a deletion of the substrate-binding and catalytic sites and the fibronectin type II-like and hemopexin/TIMP2 binding domains. Based on molecular modeling, the missense mutation disrupts hydrogen bond formation within the highly conserved prodomain adjacent to the catalytic zinc ion.     

沼气在果菜粮贮藏业上的应用

文中介绍沼气这种新型绿色能源在果菜粮贮藏中的应用情况,详尽描述了其在贮藏果品、蔬菜中的应用过程,文中对其作用的原理和益处也给予了适当介绍。     

Expression and Characterization of HGV E2 cDNA in Pichia pastoris

A 559 base pair fragment of cDNA locating at the putative E2 region of GBV-C/HGV was in-serted into Pichia pastoris expression vector pPICgK in the reading frame of α-factor secreting signal pep-tide. The recombinant expression plasmid pPIC9K-E2 was introduced into P. pastoris GSll5 with electro-poration and recombined with the host genome by homological recombination. The His+Mut+ recombinantyeasts were selected and cultivated in the BMMY medium. After 3 days induction with 0. 5% methanol,the target protein(E2) accumulated up to 30% of total proteins in the supernatant. The expressed E2 pro-tein was proved possessing antigenicity and high specificity with Western blot and ELISA probed with serafrom the immunized rabbits and the patients infected by GBV-C/HGV.     

AC发泡剂新工艺研究—Ⅲ电解氧化法

用钌钛金属阳极在含有Ｃｌ—和Ｂｒ－离子的酸性溶液中进行电解氧化联二脲制备偶氮二甲酰胺，获得产品得率为９３—９８％、纯度为９９．６％、电流效率为８８－９２％。母液可循环使用，基本不产生废液．