On-line thermal monitoring of aspartic acid separation in a high voidage ion-exchange column at high flow rate

A simple thermal monitoring technique has been successfully applied to an adsorption system using a novel ion exchanger with a large internal void volume (voidage) which can be operated at high superficial velocity (SV). Temperature changes resulting from heats of adsorption could be followed effectively using semi-conductor thermistor devices inserted into the resin through the column wall. Results show that, despite the high feed rates adopted, the thermal signals generated can be consistently related to the position of the breakthrough front within the bed.     

TRK1 and TRK2 encode structurally related K+ transporters in Saccharomyces cerevisiae.

We describe the cloning and molecular analysis of TRK2, the gene likely to encode the low-affinity K+ transporter in Saccharomyces cerevisiae. TRK2 encodes a protein of 889 amino acids containing 12 putative membrane-spanning domains (M1 through M12), with a large hydrophilic region between M3 and M4. These structural features closely resemble those contained in TRK1, the high-affinity K+ transporter. TRK2 shares 55% amino acid sequence identity with TRK1. The putative membrane-spanning domains of TRK1 and TRK2 share the highest sequence conservation, while the large hydrophilic regions between M3 and M4 exhibit the greatest divergence. The different affinities of TRK1 trk2 delta cells and trk1 delta TRK2 cells for K+ underscore the functional independence of the high- and low-affinity transporters. TRK2 is nonessential in TRK1 or trk1 delta haploid cells. The viability of cells containing null mutations in both TRK1 and TRK2 reveals the existence of an additional, functionally independent potassium transporter(s). Cells deleted for both TRK1 and TRK2 are hypersensitive to low pH; they are severely limited in their ability to take up K+, particularly when faced with a large inward-facing H+ gradient, indicating that the K+ transporter(s) that remains in trk1 delta trk2 delta cells functions differently than those of the TRK class.     

Nuclear functions required for cytochrome c oxidase biogenesis in Saccharomyces cerevisiae. Characterization of mutants in 34 complementation groups

To identify nuclear functions required for cytochrome c oxidase biogenesis in yeast, recessive nuclear mutants that are deficient in cytochrome c oxidase were characterized. In complementation studies, 55 independently isolated mutants were placed into 34 complementation groups. Analysis of the content of cytochrome c oxidase subunits in each mutant permitted the definition of three phenotypic classes. One class contains three complementation groups whose strains carry mutations in the COX4, COX5a, or COX9 genes. These genes encode subunits IV, Va, and VIIa of cytochrome c oxidase, respectively. Mutations in each of these structural genes appear to affect the levels of the other eight subunits, albeit in different ways. A second class contains nuclear mutants that are defective in synthesis of a specific mitochondrial-encoded cytochrome c oxidase subunit (I, II, or III) or in both cytochrome c oxidase subunit I and apocytochrome b. These mutants fall into 17 complementation groups. The third class is represented by mutants in 14 complementation groups. These strains contain near normal amounts of all cytochrome c oxidase subunits examined and therefore are likely to be defective at some step in holoenzyme assembly. The large number of complementation groups represented by the second and third phenotypic classes suggest that both the expression of the structural genes encoding the nine polypeptide subunits of cytochrome c oxidase and the assembly of these subunits into a functional holoenzyme require the products of many nuclear genes.     

血友病患者血清中淋巴腺病病毒/人T细胞Ⅲ型病毒抗体检测

对浙江省1982～1984年注射了美国产浓缩Ⅶ因子制剂的18例血友病患者,用酶联免疫吸附法(ELTSA)检测了血清中淋巴腺病病毒/人T细胞Ⅲ型病毒(LAV/HTLV-Ⅲ)抗体,发现4例阳性,并经免疫荧光试验和Western印迹法证实。2例应用了国产浓缩Ⅷ因子者抗体阴性。一例从美国来华旅游死于艾滋病者,LAV/HTLV-Ⅲ抗体阳性。本研究证明,LAV/HTLVⅢ病毒巳通过美国生产的Ⅷ因子制剂传入中国。     

Lipid peroxidation in liver, plasma, and erythrocytes of rats chronically treated with ethanol

The effect of ingestion of water containing 20% ethanol for 1-2 months on lipid peroxide levels of liver, plasma, and erythrocyte was investigated in rats. Our results show that elevated plasma lipid peroxide levels and erythrocyte susceptibility to lipid peroxidation may reflect stimulated lipid peroxidation in rat liver following chronic ethanol ingestion.     

Isolation of specific antigens from Angiostrongylus cantonensis. 1. Preparative flatbed isoelectric focusing

Electrophoresis on SDS gel and analytical isoelectric focusing showed that a crude extract of Angiostrongylus cantonensis consisted of at least 40 protein components with molecular weights ranging from 13 000-70 000 and isoelectric points of pI values ranging from 3.7-10.0. Crossed-immunoelectrophoresis with a hyperimmune antiserum to A. cantonensis showed at least 40 different antigenic components in the crude worm extract which were cross-reactive with those of Ascaris suum, Metastrongylus apri and Toxocara canis. Using preparative isoelectric focusing, the somatic worm preparation was divided into 13 equal fractions, of which 3, 4 and 5, with pI values of 3.7, 4.0 and 4.45 respectively, were later shown by immunoelectrophoretic techniques and enzyme-linked immunosorbent assay to contain antigens specific to A. cantonensis.     

中国人ε珠蛋白基因5′侧序列中多态性Hinc Ⅱ位点的进一步研究

本文进一步研究了我国不同民族的正常个体以及β地中海贫血患者θ珠蛋白基因5′侧序列中的多态性HincⅡ位点及其遗传性质。在广西壮族正常个体和β地中海贫血纯合子中,该多态性位点的发生频率均为75％,与正常汉族人测得值相近。家系分析资料表明,该多态性位点完全按照孟德尔规律进行遗传。