Intermediates of adeno-associated virus DNA replication in vitro.

Intermediates of adeno-associated virus type 2 (AAV) DNA replication in an in vitro assay have been characterized. The assay involves rescue and replication of an AAV insert in pBR322. Intermediates were shown to be duplex molecules in which at least one terminus was in the extended configuration, in contrast to the hairpinned ends seen after rescue in the absence of AAV DNA replication. Also present were linear double-stranded dimers, which were characterized as either head-to-head or tail-to-tail tandems; no head-to-tail dimers were detected. The results are in accord with the current model of AAV DNA replication.     

零下低温对杂交杨树皮层膜脂组成的影响

以不耐寒的美洲黑杨（Ｐｏｐｕｌｕｓｄｅｌｔｏｉｄｅｓｃｖ．“Ｌｕｘ”Ｉ－６９／５５,父本）和耐寒性较强的欧美杨（Ｐ．ｅｕｒａｍｅｒｉｃａｎａｃｌｃｖ．Ｉ－４５／５１,母本）的４个杂交Ｆ＿１代无性系（９５杨、５５９杨、６００杨和１３８１杨）为材料,分析了零下低温寒潮前后枝条皮层的脂质组成。结果表明,寒潮影响下,皮层中磷脂含量增加而组成基本不变,膜脂脂肪酸组成的变化规律是：寒潮前脂肪酸不饱和指数（ＩＵＦＡ）值大的无性系,寒潮前后的ＩＵＦＡ值变化量小;寒潮前ＩＵＦＡ值较小的无性系,寒潮前后ＩＵＦＡ值变化量较大。本文借用力学概念,提出相对抗性概念,给出杨树无性系的相对抗性序列。序列表明Ｆ＿１代无性系的耐寒性已较不耐寒的父本提高,这与田间观察基本一致。     

Absence of a direct role for RNase HI in initiation of DNA replication at the oriC site on the Escherichia coli chromosome.

On the basis of the experiments carried out with rnhA224 mutants, we previously concluded that RNase HI is not essential for initiation of Escherichia coli chromosome replication at oriC (T. Kogoma, N.L. Subia, and K. von Meyenburg, Mol. Gen. Genet. 200:103-109, 1985). In light of the recent finding that rnhA224 is a UGA nonsense mutation which can be leaky in certain genetic backgrounds, we reexamined this conclusion with the use of rnhA339 (Null)::cat mutants. The possibility that recB+ is required for initiation at the alternative origins (oriKs) of replication in rnhA mutants was also tested. The results clearly indicated that RNase HI is not essential for oriC initiation and that recB+ is not required for initiation at oriK sites.     

黄精凝集素Ⅱ分子稳定性与生物学活性研究

黄精凝集素Ⅱ分子稳定性与生物学活性研究鲍锦库,曾仲奎,周红（四川大学生物系,成都,６１００６４）本文在黄精凝集素Ⅱ纯化及性质研究的基础上,应用多种变性条件,研究其分子特性,同时对分子的巯基和色氨酸进行修饰,研究该凝集素分子保持其生物学活性与这些基团的...     

A NEW SPECIES OF GENUS HABROPHLEBIODES ULMER (EPHEMEROPTERA: LEPTOPHLEBIIDAE)

Abstract  The present paper deals with a new species Habrophlebiodes zijinensis sp. nov. collected in Nanjing, Jiangsu Povince, China.     

Characterization of human glucocerebrosidase from different mutant alleles.

Human cDNA was mutagenized to duplicate six naturally occurring mutations in the gene for glucocere-brosidase. The mutant genes were expressed in NIH 3T3 cells. The abnormal human enzymes were purified by immunoaffinity chromatography and characterized. The Asn370----Ser mutant protein differed from normal enzyme in its inhibition by both conduritol B epoxide and glucosphingosine demonstrating that the 370 mutant enzyme has an abnormal catalytic site. In addition, the 370 mutant enzyme is less activated by saposin C, but more stimulated by phosphatidylserine than the wild type enzyme. The Arg463----Cys mutant protein was normal with respect to conduritol B epoxide and glucosphingosine inhibition, but was less activated by both saposin C and phosphatidylserine. The Arg120----Gln mutant protein was catalytically inactive. The Leu444----Pro, the pseudopattern, and the Pro415----Arg mutants appear to have reduced amounts of enzyme protein in cells. The studies demonstrated that mutations in the gene for glucocerebrosidase have different effects on the catalytic activity and stability of the enzyme.     

The organization of the gene for the human cerebroside sulfate activator protein

The organization of 14 exons covering 97% of the cDNA sequence of human cerebroside sulfate activator protein precursor has been determined from two overlapping EMBL-4 human genomic clones extending over 17kb. All exons and exon/intron splice junctions and five introns were sequenced. Exon 8 consists of only 9 bp and is involved in alternative splicing which generates three different mRNAs of cerebroside sulfate activator precursor.     

Karyotypes of Pneumocystis carinii from Korean rats.

Molecular karyotyping was applied to Pneumocystis carinii(Pc) from two strains of experimental rats, Sprague Dawley(SD) and Fisher(F), in Korea. Field inversion gel electrophoresis and contour clamped homogeneous electric field electrophoresis resolved 15 chromosomal bands from the Pc. The size of the bands was estimated 270kb to 684kb from SD rats, and 273kb to 713 kb from F rats. The bands of 283 kb from SD rats and of 273 kb from F rats stained more brightly suggesting duplicated bands. Total number of chromosomes was at least 16, and total genomic size was estimated 7 x 10(6) bp. All of the bands from F rats hybridized to the probe of repeated DNA sequences of Pc and the band of 448 kb size was proved to contain rDNA sequences, but Pc. chromosome bands from SD rats showed no reactions to the probes. The 2 different karyotypes of P. carinii from 2 strains of rats were maintained consistently for 2 years.