Detection of T-2 toxin by an improved radioimmunoassay

T-2 toxin in serum, urine, and saline was analyzed by a modified radioimmunoassay procedure. The specimens were added directly to the assay tubes without extraction steps. The reaction between antibody and ligands was optimal at 1 h. Albumin-coated charcoal was used to separate bound from free radioactivity. Quenching, which occurred with hemolyzed specimens, was corrected by a wet oxidation process with 60% perchloric acid and 30% hydrogen peroxide. The shorter incubation times resulted in an assay that takes less than 6 h to complete. The average affinity constant of the antibody (Km) was 1.75 X 10(10) liters/mol. The sensitivity was 1 ng per assay or 10 ng/ml. Among the other trichothecenes tested, only H-T-2 cross-reacted significantly (10.3%).     

根霉葡萄糖淀粉酶的复性复活动力学研究

本文利用荧光、紫外差光谱研究了根霉葡萄糖淀粉酶在盐酸胍变性后的复性、复活动力学。结果表明,该酶在小于4mol/L盐酸胍中变性是可逆的,其复性过程遵循一级反应方程。酶复活过程是由两个一级反应组成的复合反应,构象变化速度与复活过程中较快的反应速度相差无几,这可能是在Trp及Tyr微区的构象变化基本完成之后,酶活力恢复还没有完成造成的。     

Trypsin inhibitor from the seeds of Acacia confusa.

A trypsin inhibitor (ACTI) was isolated and purified from the seeds of Acacia confusa by gel filtration, and trypsin-Sepharose 4B column affinity chromatography. The molecular weight of ACTI was found to be 21,000 +/- 1,000 by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and amino acid composition analysis. ACTI contained four half-cystine and no methionine residues, and was rich in aspartic acid, glutamic acid, glycine, leucine, and lysine residues. The native trypsin inhibitor was composed of two polypeptide chains, and it inhibited trypsin and alpha-chymotrypsin stoichiometrically at the molar ratio of 1:1 and 2:1, respectively. The amino-terminal sequence analysis of the A. confusa trypsin inhibitor A and B chains revealed a more extensive homology with Acacia elata and silk tree trypsin inhibitors, and a less extensive homology with Kunitz soybean trypsin inhibitor.     

Human alpha 3(VI) collagen gene. Characterization of exons coding for the amino-terminal globular domain and alternative splicing in normal and tumor cells

We recently reported the isolation and sequencing of human cDNA clones corresponding to the alpha 3 chain of type VI collagen (Chu, M.-L., Zhang, R.-Z., Pan, T.-c., Stokes, D., Conway, D., Kuo, H.-J., Glanville, R., Mayer, U., Mann, K., Deutzmann, R., and Timpl, R. (1990) EMBO J. 9, 385-393). The study indicates that the amino-terminal globular domain of the alpha 3(VI) chain consists of nine repetitive subdomains of approximately 200 amino acid residues (N1-N9) and the gene appeared to undergo alternative splicing since some clones lacked regions encoding the N9 and part of the N3 subdomains. In the present study, we report the exon structure for the region encoding the amino-terminal globular domain of the human alpha 3(VI) chain. The nine repetitive subdomains are encoded by 10 exons spanning 26 kilobase pairs of genomic DNA. Eight of the repetitive subdomains (N2-N9) were found to be encoded by separate exons of approximately 600 base pairs each. The only exception is the N1 subdomain which is encoded by two exons of 417 and 146 base pairs. Characterization of the exon/intron structure showed that the cDNA variants were the result of splicing out of exon 9 (encoding the N9 subdomain) and part of exon 3 (encoding the N3 subdomain). Nuclease S1 analysis and the polymerase chain reaction demonstrated that exon 7 (N7 subdomain) was also subject to alternative splicing in normal skin fibroblasts. Examination of these splicing events by nuclease S1 analysis in normal fibroblasts, three different human tumor cell lines, and several human tissues showed that splicing out of exon 9 is much more efficient in normal as compared to tumor cells.     

Native and exotic species of dioscorea used as food in brazil

The major reserve compounds of tubers (starch, soluble carbohydrates, proteins and non-soluble fibers) of five native Dioscorea species are analyzed with a view to their economic importance (for the staple food and pharmaceutical industries); distribution, phenology and germination are also investigated. Twenty-six native species and the cultivated edible exotics are listed, with phenological characteristics, popular name, habitat, popular medicinal importance and distribution.     

元谋新第三纪食肉动物化石的初步观察

本文对云南元谋盆地产古猿化石地点的部分食肉类化石进行了初步观察分类,认为它们的时代似应稍晚于禄丰,相当上新世早期,估计距今5-6百万年.     

病毒衣壳结构亚单位的种类数与三角形剖分数关系的研究和探讨

本文报道了在正廿面体病毒衣壳中,当蛋白结构亚单位以“三聚体”的形式聚集在单位三角形(?)时,其亚单位的种类数应等于该病毒的三角形剖分数值。     

Cloning and sequence analysis of the muramidase-2 gene from Enterococcus hirae.

Extracellular muramidase-2 of Enterococcus hirae ATCC 9790 was purified to homogeneity by substrate binding, guanidine-HCl extraction, and reversed-phase chromatography. A monoclonal antibody, 2F8, which specifically recognizes muramidase-2, was used to screen a genomic library of E. hirae ATCC 9790 DNA in bacteriophage lambda gt11. A positive phage clone containing a 4.5-kb DNA insert was isolated and analyzed. The EcoRI-digested 4.5-kb fragment was cut into 2.3-, 1.0-, and 1.5-kb pieces by using restriction enzymes KpnI, Sau3AI, and PstI, and each fragment was subcloned into plasmid pJDC9 or pUC19. The nucleotide sequence of each subclone was determined. The sequence data indicated an open reading frame encoding a polypeptide of 666 amino acid residues, with a calculated molecular mass of 70,678 Da. The first 24 N-terminal amino acids of purified extracellular muramidase-2 were in very good agreement with the deduced amino acid sequence after a 49-amino-acid putative signal sequence. Analysis of the deduced amino acid sequence showed the presence at the C-terminal region of the protein of six highly homologous repeat units separated by nonhomologous intervening sequences that are highly enriched in serine and threonine. The overall sequence showed a high degree of homology with a recently cloned Streptococcus faecalis autolysin.