Organization of the gene for human factor XI

Factor XI (plasma thromboplastin antecedent) is a plasma glycoprotein that participates in the early phase of blood coagulation. The gene for the human protein has been isolated from two different lambda phage genomic libraries. Four independent recombinant lambda phage carrying overlapping DNA inserts that coded for the entire gene for factor XI were isolated and characterized by restriction mapping, Southern blotting, and selective DNA sequencing to establish the number and location of the intron-exon boundaries. The gene for human factor XI was 23 kilobases in length and consisted of 15 exons (I-XV) and 14 introns (A-N). Exon I coded for the 5' untranslated region, and exon II coded for the signal peptide. The next eight exons (III-X) coded for the four tandem repeats of 90 or 91 amino acids that were present in the amino-terminal region of the mature protein. Each of these tandem repeats was coded by two exons that were interrupted by a single intron, and these introns were located in essentially the same position within each of the four tandem repeats. The carboxyl-terminal region of the protein, which contained the catalytic chain, was coded by five exons (XI-XV) that were interrupted by four introns. The last four introns were located in the same positions as those in the genes for human tissue plasminogen activator and human urokinase.     

复眼透镜光学信息保密编码及译码的研究——Ⅱ.分解掩模编码与综合再现

本文根据复眼透镜光学信息编译码的技术原理,实现了对二维图像进行分解编码记录以及综合译码再现.一幅m×n个目标单元的二维图像,通过1×k阵列的复眼透镜,得到(1×k)(m×n)个像元.经过一个特制的掩模板,得到一幅随机分解编码像,并根据透镜的物、像共轭原理,综合再现了原始图像.进而还实现了同时记录多幅二维图像信息的互补编码像,以及将互补编码像分离重现了每一幅原始目标图像.此互补编码像携带了更大的信息量,同时也大大提高了保密性能.     

Reducing the number of microlocations in oligonucleotide microchip matrices by the application of degenerate oligonucleotides

The application of degenerate oligonucleotides to DNA Sequencing by Hybridisation with Oligonucleotide Matrix (SHOM) is proposed. The use of degenerate oligonucleotides is regarded as an example of pooling methods that are suitable for various laboratory procedures requiring numerous samples to be assayed. As each DNA sequence coded by four letters (A, G, C, T) may be defined by two sequences: a sequence coded by W and S (W-weak-A or T, S-strong-G or C) and a sequence coded by R and Y (R-purine-A or G, Y-pirymidine-T or C), n4n -nucleotide sequences may be defined with the help of 2xn2sequences. In the place of the originally described microchip matrix composed of all possible unambiguous octanucleotides (4(8)=65 536) attached to the equal number of 65 536 microlocations a matrix composed of 512 microlocations containing 256 2(8)-degenerate octanucleotides is proposed. The matrix contains all 256 possible octanucleotides coded by W and S variations and all 256 possible octanucleotides coded by R and Y variations. The 512 256-degenerate octanucleotides allows to retrieve the same information as 65 536 unambiguous octanucleotides. A variant of the DNA sequence reconstruction method applicable to this system is presented. The use of degenerate oligonucleotides also gives the possibility to apply matrices composed of longer oligonucleotides without increasing the number of microlocations in matrices, which would enable increasing the length of unambiguously reconstructed sequence, e.g. a matrix comprising 131 072 16-mer oligonucleotides i.e. 65 536 65 536-fold degenerate oligonucleotide coded by W and S variations and 65 536 65 536-fold degenerate oligonucleotide coded by R and Y variations could replace one matrix comprising all possible unambiguous 16-mer oligonucleotides (ca. 4.3x10(9)).     

Comparative biochemical properties of p21 ras molecules coded for by viral and cellular ras genes.

In earlier studies, we molecularly cloned a normal cellular gene, c-rasH-1, homologous to the v-ras oncogene of Harvey murine sarcoma virus (v-rasH). By ligating a type c retroviral promotor to c-rasH-1, we could transform NIH 3T3 cells with the c-rasH-1 gene. The transformed cells contained high levels of a p21 protein coded for by the c-rasH-1 gene. In the current studies, we have purified extensively both v-rasH p21 and c-rasH p21 and compared the in vivo and in vitro biochemical properties of both these p21 molecules. The p21 proteins coded for by v-rasH and c-rasH-1 shared certain properties: each protein was synthesized as a precursor protein which subsequently became bound to the inner surface of the plasma membrane; each protein was associated with guanine nucleotide-binding activity, a property which copurified with p21 molecules on a high-pressure liquid chromatography molecular sizing column. In some other properties, the v-rasH and c-rasH p21 proteins differed. In vivo, approximately 20 to 30% of v-rasH p21 molecules were in the form of phosphothreonine-containing pp21 molecules, whereas in vivo only a minute fraction of c-rasH-1 p21 contained phosphate, and this phosphate was found on a serine residue. v-rasH pp21 molecules with an authentic phosphothreonine peptide could be synthesized in vitro in an autophosphorylation reaction in which the gamma phosphate of GTP was transferred to v-rasH p21. No autophosphorylating activity was associated with purified c-rasH-1 p21 in vitro. The results indicate a major qualitative difference between the p21 proteins coded for by v-rasH and c-rasH-1. The p21 coded for by a mouse-derived oncogenic virus, BALB murine sarcoma virus, resembled the p21 coded for by c-rasH-1 in that it bound guanine nucleotides but did not label appreciably with 32Pi. The forms of p21 coded for by other members of the ras gene family were compared, and the results indicate that the guanine nucleotide-binding activity is common to p21 molecules coded for by all known members of the ras gene family.     

Occurrence of nucleotide triplets in genes and secondary structure of the coded proteins

This paper deals with general regularities of nucleotide triplet occurrence in genes of various organisms and their effects on secondary structure of the coded proteins. The strongest general regularity translated into proteins is a predominance of guanine in the first codon position and its deficit in the second codon position. This bias is mostly compensated for by a deficit of thymine in the first and excess of adenine in the second codon positions. These general regularities increase the average amounts of beta sheets and mainly alpha helices in the coded proteins, but they are far from optimal if their only purpose or origin is a promotion of spatial organization of the coded proteins.     

Amino-sugar transport systems of Escherichia coli K12

Glucosamine, mannose and 2-deoxyglucose enter Escherichia coli by the phosphotransferase system coded for by the gene ptsM. The glucosamine- and mannose-negative, deoxyglucose-resistant phenotype of ptsM mutants can be suppressed by a mutation mapping near ptsG that allows constitutive expression of the glucose phosphotransferase coded for by the gene ptsG. N-Acetylglucosamine enters E. coli by two distinct phosphotransferase systems (White, 1970). One of these is the PtsM system, the other is coded for by a gene which maps near the nagA,B genes at about min 15 on the E. coli chromosome. We propose that this gene be designated ptsN. Strains with either of these components of the phosphotransferase system will utilize N-acetylglucosamine as sole carbon source.     

Comparison of the in vitro translation products of mRNA isolated from suspension cultures of Phaseolus vulgaris grown on maintenance and induction medium

1. Bean cells grown in suspension culture on maintenance medium have been shown to differentiate (xylem and phloem production) when they are transferred to an induction medium containing an increased ratio of naphthylacetic acid to kinetin.-2. Conditions for the extraction and isolation of undegraded mRNA are described. The mRNA has been translated by 2 in vitro protein synthesizing systems; the wheat germ and the mRNA-dependent-reticulocyte-lysate preparations.-3. A greater proportion of the mRNA from cells on maintenance medium coded for high molecular weight products compared with that from cells on induction medium.-4. mRNA from cells on induction medium coded for a relatively large amount of a few polypeptides whereas that from cells on maintenance medium coded for a large number of polypeptides all present in fairly equal amounts.     

Testing for Validity and Reliability in Cross-Cultural Research

A set of procedures is offered for assessing interraler reliability and certain aspects of validity of codes in cross-cultural studies. The method assumes that at least two independent raters have coded more than one trait. Each trait coded by one rater is correlated with each trait coded by a second, and all the codings by a single rater are intercorrelated with each other. The results are presented in a multitrait-multi-rater matrix. From this matrix it is possible to determine the interrater reliability and discriminant validity of trails in addition to a higher order concept based on pairs of traits.     

Implementation of a field programmable gate array based transcranial Doppler ultrasound system using pulse compression techniques

A field programmable gate array (FPGA) based hardware platform that is used to implement a digital, multi-gate pulsed Doppler ultrasound system for transcranial Doppler (TCD) use is described. The Doppler audio signal is extracted from the digitised radio-frequency signal by matched filtering and suitable sampling. The system was configured to acquire Doppler signals from 16 depth locations and to display Doppler signal power versus depth as well as a sonogram from a user specified depth. The signal-to-noise performance of the system was comparable with that of a commercially available TCD unit for equivalent pulse repetition frequency and sample volume settings.The flexibility of the platform was used to demonstrate the feasibility of using coded transducer excitation and pulse compression techniques to improve axial resolution compared to a non-coded implementation. The axial resolution improvement was demonstrated using a flow phantom and measured using a vibrating wire phantom. The measured resolutions were 9.1 and 2.4 mm for the conventional and coded implementations, respectively. The reduction in signal-to-noise ratio of approximately 5 dB associated with the configuration using coded excitation was attributable to the frequency response characteristics of the transducer rather than the processing technique used. This work demonstrates both the flexibility associated with an FPGA implementation of a Doppler ultrasound system and the potential for coded excitation to improve axial resolution in TCD systems.     

Comparative sequence analysis of acid sensitive/resistance proteins in Escherichia coli and Shigella flexneri

The molecular basis for the survival of bacteria under extreme conditions in which growth is inhibited is a question of great current interest. A preliminary study was carried out to determine residue pattern conservation among the antiporters of enteric bacteria, responsible for extreme acid sensitivity especially in Escherichia coli and Shigella flexneri. Here we found the molecular evidence that proved the relationship between E. coli and S. flexneri. Multiple sequence alignment of the gadC coded acid sensitive antiporter showed many conserved residue patterns at regular intervals at the N-terminal region. It was observed that as the alignment approaches towards the C-terminal, the number of conserved residues decreases, indicating that the N-terminal region of this protein has much active role when compared to the carboxyl terminal. The motif, FHLVFFLLLGG, is well conserved within the entire gadC coded protein at the amino terminal. The motif is also partially conserved among other antiporters (which are not coded by gadC) but involved in acid sensitive/resistance mechanism. Phylogenetic cluster analysis proves the relationship of Escherichia coli and Shigella flexneri. The gadC coded proteins are converged as a clade and diverged from other antiporters belongs to the amino acid-polyamine-organocation (APC) superfamily.     

Serological Cross-Reactivities of Murine and Human Class II Antigen Determined by Murine Xeno Anti-Human Class II Antibody

Murine anti-human class II antibodies were shown to cross-react with polymorphic determinants of murine class II antigens. The cross-reacting antibodies were raised in B10.S(9R) mice by immunizing with human nylon wool adherent cells (Ad cells) from peripheral blood leukocytes. The B10.S(9R) anti-human Ad cell antiserum bound to the molecules consisting of two chains with molecular weights of 35K and 28K dimers which were purified with a lentil-lectin column. The B10.S (9R) anti-human class II antiserum was also revealed to contain two distinct cross-reacting antibodies with polymorphic determinants of murine class II antigens coded for by the I-A subregion of the H-2. One is specific for a determinant of class II molecules coded for by I-A^b,d,q, and the other seems to be specific for class II molecules coded for by I-A^a,k,r.     

一种基于chirp编码的高帧速率超声成像方法

在医学超声成像系统中,帧速率由每帧图像的扫查发射次数所决定.同时发射多条波束可以提高图像的帧速率,但是这会带来不同波束间相互干扰的问题,形成伪像.本文基于编码激励的原理,提出了一种新的高帧速率成像方法.该方法通过发射一组线性频率调制编码信号,有效的降低了波束间的互扰.可以在不影响图像质量的情况下,成倍的提高图像的帧速率.     

Phosphoenolpyruvate-dependent phosphotransferase system enzyme III and plasmid-encoded sucrose transport in Escherichia coli K-12.

The phosphoenolpyruvate-dependent carbohydrate:phosphotransferase system enzyme IISCR, specific for and regulated by sucrose, was analyzed in derivatives of Escherichia coli K-12 carrying the sucrose plasmid pUR404. Enzyme IIScr, coded for by gene scrA of the plasmid, depended for its transport and phosphorylation activity directly on the phosphotransferase system enzyme IIIGlc, Scr, coded for by the chromosomal gene crr.     

Isolation, characterization and evolutionary relatedness of three members from the soybean multigene family encoding chlorophyll a/b binding proteins.

The soybean light-harvesting complex II (LHC II) was composed of one major and three minor chlorophyll a/b (Cab) binding proteins. This study demonstrated that the soybean genome contained at least 11 genes that code for these Cab proteins. Three members of the soybean Cab gene family were characterized. Cab 3 coded for a 25.7 kD mature apoprotein with a 32 amino acid transit peptide. Comparisons with previously published Cab protein sequences indicated that Cab 3 coded for the major Cab protein of LHC II. Cab 2 coded for a novel Cab protein with an apparent molecular weight of 24.6 kD. Cab 2 retained a high degree of similarity with Cab 3, but distinguished itself from previously reported minor photosystem II type II Cab genes and products. Finally, Cab 1 was determined to be a pseudogene that had two deletions relative to Cab 2 and Cab 3.     

Analysis of mRNA coding for blood-stage antigens of a rodent malarial parasite, Plasmodium yoelii: mRNA coding for a possible protective antigen purify as poly A-

We have analyzed mRNA coding for blood-stage antigens of Plasmodium yoelii by using cellfree translation of poly A+ and poly A- RNA in conjunction with immunoprecipitations. Most of the antigens recognized by mouse hyperimmune serum to P. yoelii were coded by poly A+ mRNA ranging in size from 15S to 28S. However, certain P. yoelii antigens, notably those with m.w. greater than 150 kilodaltons (kd), were coded by mRNA that purified as being poly A-. Antigens recognized by a protective monoclonal antibody (McAb) were coded by such operationally poly A- RNA. Three polypeptides apparently coded by different poly A- RNA were immunoprecipitated by this McAb. With the use of another McAb, a poly A+ mRNA of about 19S was identified as coding for a polypeptide of 46 kd synthesized in cellfree translation reactions. The same McAb recognized a 34 kd polypeptide in metabolically labeled polypeptides of P. yoelii. This antigen appeared to be processed in vivo but not in vitro. The observation that some mRNA of P. yoelii purify as being poly A- has significant implications for the construction of cDNA libraries that employ poly A+ mRNA of malarial parasites: if it applies to other species of plasmodia, some potentially important operationally poly A- mRNA may not be represented in such libraries.     

Report of a collaborative study to assess the suitability of a reference reagent for antibodies to hepatitis E virus.

Several commercial and "in-house" assays have been developed for the detection of antibodies to hepatitis E virus, a major causative agent of enterically transmitted non-A non-B hepatitis. As these kits contain a variety of synthetic peptides or recombinant proteins, greater standardisation is required. A collaborative study was therefore carried out to assess the suitability of a freeze dried preparation designated 95/584 to serve as a reference reagent for hepatitis E virus serum IgG. Preparation 95/584, which is a serum from a previously infected individual, was assayed along with four coded samples, one of which D, was a coded duplicate of 95/584, and three individual sera, coded A, B and C. These preparations were sent to seven laboratories in five countries who tested them in eight different enzyme immunoassays. In most laboratories the coded duplicate gave a mean potency of within 20% of the candidate reference reagent despite the wide range of assays used. However, the potencies of the coded samples which were from different individuals gave somewhat variable potencies relative to the candidate reference reagent. This is not surprising as each sample will have varying proportions of antibodies against individual viral proteins and result in the variation in results observed. Nevertheless, this material will be of use in the standardisation of diagnostic tests for use in sero-prevalence studies and for assessing immunity. Preparation 95/584 was found to be suitable to serve as a reference reagent for hepatitis E serum IgG and has been established as an interim Reference Reagent for Human anti-hepatitis E serum. Each ampoule contains 50 Units per ampoule.     

Two genes, atpC1 and atpC2, for the gamma subunit of Arabidopsis thaliana chloroplast ATP synthase.

Arabidopsis thaliana has two genes (atpC1, atpC2) coding for gamma subunits of chloroplast ATP synthase. The atpC1 and atpC2 were cloned and sequenced. They had no introns within the reading frames and coded for proteins of 373 and 386 amino acid residues, respectively, including putative transit sequences (50 and 60 amino acid residues, respectively). In contrast, the spinach gamma subunit gene had two introns within the reading frame. The mature sequences coded by the two genes of A. thaliana (atpC1, 323 residues; atpC2, 326 residues) were homologous with that of spinach (J. Miki, M. Maeda, Y. Mukohata, and M. Futai (1988) FEBS Lett. 232, 221-226): the homologies of gamma subunits coded by atpC1 and atpC2 were 72%, those of the subunits coded by atpC1 and spinach cDNA were 84%, and those of the proteins coded by atpC2 and spinach cDNA were 71%. Like the spinach subunit, the gamma subunits coded by the two genes had unique regulatory domains not found in mitochondrial or bacterial subunits. Poly(A)+ mRNAs corresponding to atpC1 (1.5 kilobases) and atpC2 (2.5 kilobases) were detected in illuminated plants, the amount of the former being at least 140 times that of the latter. The atpC1 mRNA was not found in dark-adapted plants. Nuclear protein(s) specifically bound to the upstream region of atpC1 was detected by gel shift assay and its binding was shown to be inhibited by the GT-1 element of the gene encoding the ribulose-1,5-bisphosphate carboxylase small subunit, which is expressed under illumination (P. J. Green, S. A. Kay, and N. H. Chau (1987) EMBO J. 6, 2543-2549). Consistent with these findings, an increased amount of the gamma subunit was detected immunochemically in illuminated plants.