Geographical variability of alpha-1-antitrypsin alleles in China: A study on six Chinese populations

Summary Alpha-1-antitrypsin phenotypes of six Chinese Han populations (20°–45°N. latitude) were determined. The frequency of allele M2 increases from North to South China. The north-south change of M2 appears to be mainly at the expense of alleles M1 and M3. Geographical variability of other variants was also observed. In the northern populations, the most common variants are M4 and Etokyo; in the southern populations, Pweishi, a variant which can not be distinguished electrophoretically from Pyasugi. These results form a distribution pattern of alpha-1-antitrypsin alleles in China.     

Isolation of chitin synthetase from Saccharomyces cerevisiae. Purification of an enzyme by entrapment in the reaction product

Chitin synthetase, in the zymogen form, was extracted with digitonin from a particulate fraction from Saccharomyces cerevisiae and converted into active form by treatment with immobilized trypsin. When the activated enzyme was incubated with UDP-GlcNAc and other components of an assay mixture, a chitin precipitate formed, trapping a large portion of the synthetase. The enzyme was easily extracted frm the chitin gel with a recovery of approximately 50% and an enrichment of approximately 100-fold. Further purification was obtained by repeating the chitin step. After polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate, the purified synthetase showed a major band corresponding to Mr 63,000, a weaker band at Mr 74,000, and some other minor bands. Under nondenaturing conditions, an Mr of 570,000 was calculated for the enzyme from Stokes radius and sedimentation coefficient determinations. After electrophoresis in a nondenaturing gel and incubation with the components of the standard assay, chitin was formed and precipitated in the gel, yielding an opaque band. Soluble oligosaccharides were not precursors for insoluble chitin, suggesting that synthesis of chitin chains takes place by a processive mechanism. N-Acetylglucosamine stimulated the purified synthetase only slightly and did not participate as a primer in the reaction. The same chain length, somewhat more than 100 units of GlcNAc, was determined in samples of chitin that had been synthesized either in vivo, or with a membrane preparation or with purified synthetase. These results suggest that chitin synthetase itself is capable both of initiating chitin chains without a primer and of determining their length.     

Structural characterization of virion proteins and genomic RNA of human parainfluenza virus 3

The virion proteins and genomic RNA of human parainfluenza virus 3 have been characterized. The virion contains seven major and two minor proteins. Three proteins of 195 X 10(3) molecular weight (195K), 87K, and 67K are associated with the nucleocapsid of the virion and have been designated L, P, and NP, respectively. Three proteins can be labeled with [14C]glucosamine and have molecular weights of 69K, 60K, and 46K. We have designated these proteins as HN, F0, and F1, respectively. HN protein has interchain disulfide bonds, but does not participate in disulfide bonding to form homomultimeric forms. F1 appears to be derived from a complex, F1,2, that has an electrophoretic mobility similar to that of F0 under nonreducing conditions. A protein of 35K is associated with the envelope components of the virion and aggregates under low-salt conditions; this protein has been designated M. The genome of human parainfluenza virus 3 is a linear RNA molecule with a molecular weight of approximately 4.6 X 10(6).     

牛病毒性腹泻病毒单克隆抗体的研究

牛病毒性腹泻——粘膜病是世界性广泛流行的奶牛和肉牛的传染病。其病原为牛病毒性腹泻病毒(BVDV),属于披膜病毒科的瘟病毒属,它的许多生物学特性至今还不很清楚。本试验建立了12株分泌抗BVDV的单克隆抗体(McAb)杂交瘤细胞株,并结合免疫转移电泳法和放射免疫沉淀法,初步研究了BVDV的多肽。     

克山病是一种“心肌线粒体病(Mitochondrial Cardiomyopathy)”

亚急克病人心肌线粒体内膜电子传递链的琥珀酸氧化酶系,琥珀酸脱氢酶和细胞色素氧化酶活性明显低于对照。H~ -ATP酶的活性及其对寡霉素的敏感性都明显下降。ATP能量化后线粒体膜电位的变化也比对照明显降低。膜脂流动性低于对照。亚急克病人心肌线粒体内观察到较多的电子致密无定形物质,经电镜X射线微区等方法分析,认为这些物质不是Ca_3(PO_4)_2,而可能是一种蛋白质凝聚物。此外,心肌线粒体的硒含量远低于对照,而Ca含量明显高于对照。上述结果都反映亚急克病人心肌线粒体明显损伤。根据克山病患者心肌细胞线粒体结构与功能方面呈现的如此广泛与明显的异常,可将克山病称为“心肌线粒体病(Mitochondrial Cardiomyopathy)”。     

Primary structure of PDC-109, a major protein constituent of bovine seminal plasma

The two major protein components of bovine seminal plasma, PDC-109 and BSP I, have been purified by gel filtration, partition chromatography and reverse-phase high performance liquid chromatography from an 86% ethanol precipitate of bovine seminal plasma ejaculate. The complete 109-residue amino acid sequence of PDC-109 has been established by automated Edman degradation of the intact peptide as well as its proteolytic digestion and cyanogen bromide cleavage fragments. The 12,774 dalton structure has two structurally similar domains of 38 and 41 amino acids, each containing two disulfide bonds.     

Alterations in the Structure of the Oligosaccharide of Vesicular Stomatitis Virus G Protein by Swainsonine

Swainsonine, an inhibitor of glycoprotein processing, inhibits the formation of the normal oligosaccharide chain of the G protein of vesicular stomatitis virus. Thus, when vesicular stomatitis virus was grown in baby hamster kidney cells in the presence of swainsonine (15 to 500 ng/ml) and labeled with [2-(3)H]mannose, the oligosaccharide portion of the G protein was completely susceptible to the action of endoglucosaminidase H. However, the normal viral glycoprotein is not susceptible to this enzyme. Various enzymatic treatments and methylation studies of the mannose-labeled oligosaccharides suggest that swainsonine causes the formation of a hybrid-type oligosaccharide having an oligomannosyl core (Man(5)GlcNAc(2)-Asn) characteristic of neutral oligosaccharides plus the branch structure (NeuNAc-Gal-GlcNAc) characteristic of the complex oligosaccharides. A structure for this hybrid oligosaccharide is proposed. Swainsonine had no effect on the incorporation of [(14)C]leucine into viral proteins, nor did it change the number of PFU produced in these cultures. It did, however, slightly decrease the incorporation of [(3)H]glucosamine and increase the incorporation of [(3)H]mannose. Vesicular stomatitis virus raised in the presence of swainsonine bound much more tightly to columns of concanavalin A-Sepharose than did control virus. Swainsonine had to be added within the first 4 or 5 h of virus infection to be effective. Thus, when 100 ng of the alkaloid per ml was added at any time within the first 3 h of infection, essentially all of the glycoprotein was susceptible to digestion by endoglucosaminidase H. However, when swainsonine was added 4 h after the start of infection, 30% of the glycopeptides became resistant to endoglucosaminidase H; at 5 h, 70% were resistant. The effect of swainsonine was reversible since removal of the alkaloid allowed the cells to form the normal complex glycoproteins. However, the time of removal was critical in terms of oligosaccharide structure.     

Deoxyribonucleic Acid Replication in Simian Virus 40-Infected Cells IV. Two Different Requirements for Protein Synthesis During Simian Virus 40 Deoxyribonucleic Acid Replication

The replication of simian virus 40 (SV40) deoxyribonucleic acid (DNA) was inhibited by 99% 2 hr after the addition of cycloheximide to SV40-infected primary African green monkey kidney cells. The levels of 25S (replicating) and 21S (mature) SV40 DNA synthesized after cycloheximide treatment were always lower than those observed in an infected untreated control culture. This is consistent with a requirement for a protein(s) or for protein synthesis at the initiation step in SV40 DNA replication. The relative proportion of 25S DNA as compared with 21S viral DNA increased with increasing time after cycloheximide treatment. Removal of cycloheximide from inhibited cultures allowed the recovery of viral DNA synthesis to normal levels within 3 hr. During the recovery period, the ratio of 25S DNA to 21S DNA was 10 times higher than that observed after a 30-min pulse with (3)H-thymidine with an infected untreated control culture. The accumulation of 25S replicating SV40 DNA during cycloheximide inhibition or shortly after its removal is interpreted to mean that a protein(s) or protein synthesis is required to convert the 25S replicating DNA to 21S mature viral DNA. Further evidence of a requirement for protein synthesis in the 25S to 21S conversion was obtained by comparing the rate of this conversion in growing and resting cells. The conversion of 25S DNA to 21S DNA took place at a faster rate in infected growing cells than in infected confluent monolayer cultures. A temperature-sensitive SV40 coat protein mutation (large-plaque SV40) had no effect on the replication of SV40 DNA at the nonpermissive temperature.