Analysis of Schizosaccharomyces pombe mitochondrial DNA replication by two dimensional gel electrophoresis

The entire mitochondrial genome of Schizosaccharomyces pombe ura4-294h ^-was analyzed by the 2D pulsed field gel electrophoresis technique developed by Brewer and Fangman. The genome consists of multimers with an average size of 100 kb and analysis of the overlapping restriction fragments of the complete mitochondrial DNA (mtDNA) genome resulted in simply Y 2D gel patterns. Large single-stranded DNA molecules or double-stranded DNA molecules containing large or numerous single-stranded regions were found in the S. pombe mtDNA preparation. The replication of mtDNA monomers was found to occur in either direction. On the basis of these results, a replication mechanism for S. pombe mtDNA that is most consistent with a rolling circle model is suggested.     

Effects of quality and developmental stage on the survival of IVF-derived bovine blastocysts cultured in vitro after freezing and thawing

Factors affecting viability of IVF-derived bovine blastocysts after freezing and thawing were investigated. A total of 1,101 ova matured and fertilized in vitro were cultured under 2 different conditions, 1) in TCM-199 on granulosa cell monolayers at 5% CO(2) in air and 2) in synthetic oviduct fluid (SOF) medium without somatic cell support at 5% CO(2), 5% O(2), 90% N(2). All blastocysts that developed from the 2 different culture systems were individually classified into 4 grades of embryo quality and were then frozen by conventional slow freezing. Developmental rates of the IVF-derived ova to blastocysts and the survival rates of the frozen-thawed blastocysts were not different between the SOF medium (16 and 49%) and the co-culture system (13 and 61%, respectively). Survival of frozen-thawed blastocysts was affected by embryo quality in both the SOF and co-culture systems (P<0.001). Blastocysts produced in vitro were also individually classified into 3 developmental stages and were then cultured for 3 d in the co-culture system with granulosa cells after freezing and thawing. There was a difference in the survival rate of frozen-thawed embryos between blastocyst developmental stages (early vs mid, P<0.05; mid vs expanded, P<0.01; early vs expanded, P<0.001). The post-thawing survival rate of blastocysts frozen at Day 7 (62%) of culture was higher compared with that of Day 8 (45%), but there was no difference in survival rate between Day 7 and 8 of culture. The results indicate that the quality and developmental stage of blastocysts are important factors influencing their survival after freezing and thawing.     

Accumulation of cesium and radiocesium in forest litter in selected regions of poland and its influence on litter-to-mushroom transfer factor

The aim of this work was to check whether the stable cesium content in forest litter affects the value of radiocesium from litter-to-mushroom transfer factorTf or not. Total cesium in litter, measured by AAS, varied from 0.1–2.7 μg/g. These data, combined with earlier results for mushrooms, showed no simple correlation forTf. More complex relationships provided very high correlation coefficients, but their validity needs further investigation.     

Polish Glomales

Spores of Acaulospora dilatata and Scutellospora dipurpurascens found in Poland are described and illustrated and their occurrence and distribution are characterized and mapped. Spores of Acaulospora dilatata from Poland do not differ from those originally described in the United States of America. The germination shield found in a number of spores is described and illustrated, and compared with that occurring in members of the genus Scutellospora. Acaulospora dilatata was found in five of the 303 soil samples taken from around the roots of Ammophila arenaria colonizing maritime sand dunes of the Sowinski National Park. Polish specimens of S. dipurpurascens are similar in size, wall structure, and reaction in Melzer's reagent to those described from the type localized in the United States of America. However, some spores from Poland have a thicker wall, greater sporogenous cells, and are somewhat darker coloured. They were recovered from 34 soils sampled from forests, gardens, sand dunes, and both cultivated and uncultivated soils. S. dipurpurascens was commonly associated with different plants of the Hel Peninsula and occurred regularly among the roots of Ammophila arenaria growing in the Slowinski National Park. Both species were found for the first time in Poland and are probably new to Europe.     

Arbuscular fungi and mycorrhizae (Glomales) of the Hel Peninsula,Poland

In the years 1985–1989, the occurrence of arbuscular fungi and mycorrhizae on the Hel Peninsula (Poland) was investigated with the help of 45 soil and root samples collected under 20 plant species of eight families. Except for Zea mays, the other plant species were from uncultivated sites. All soil samples contained spores of arbuscular fungi, of which about 45% were of the genus Glomus. Acaulospora spp. preferred members of the Cupressaceae. Spores of Gigaspora occurred rarely and only in two plant families. Glomus spp. were most frequently associated with plants of the Rosaceae, and species of Scutellospora were found at markedly higher frequencies among roots of plants of the Gramineae and Cupressaceae. A total of 29 spore-forming species and Glomus tenue (a fungus recognizable by its distinctive infections) were found. The most frequently recovered fungus, Glomus tenue, was present in roots of 56.8% of examined plants. Of the spore-forming fungi, the most frequently isolated spores were those of Scutellospora dipurpurascens, then Glomus constrictum, Acaulospora 61, and Glomus microcarpum. The overall spore density in examined samples averaged 99.8 in 100 g dry soil in the range 1 to 547, and was highest in a sample taken from around roots of Festuca arundinacea. The dominant fungi forming spores in sampled soils were Glomus constrictum, Glomus microcarpum, and Scutellospora dipurpurascens. The average species density was 3.9 in 100 g dry soil in the range 1 to 10, and was highest in Corynephorus canescens, Rosa canina, and Thuja occidentalis. Levels of colonization by arbuscular fungi ranged from 0.0 to94.0% (mean 23.3%) of the root length and were highest in Festuca arundinaceae and Zea mays.     

Rapid screening of an SH2-containing gene using PCR amplification method

Summary To isolate a novel gene that contains an SH2 domain, we devised a rapid and nonradioactive cDNA library screening method using polymerase chain reaction (PCR). For PCR amplification, we designed degenerate oligonucleotide primers from the multialigned DNA sequences of SH2 domains. This method offers an inexpensive and efficient approach for the isolation of clones of interest from cDNA libraries.     

Changes and Relationship of PAF and TNF in Rats with Myocardial Ischaemia and Reperfusion Injury

IN THIS STUDY IT IS REPORTED THAT: (1) the levels of blood platelet-activating factor and serum tumour necrosis factor significantly increased after coronary ligation and reperfusion, compared with sham-ligated controls, in an anaesthetized rat model; (2) compared with vehicle controls, pretreatment with the PAF antagonist BN 50739 (10 mg/kg, i.v.) produced significant decreases in infarct size (from 29.6 +/- 4.0% to 22.4 +/- 2.1%, p < 0.05 after 3 h ligation, and from 28.5 +/- 9.5% to 10.5 +/- 4.5%, p < 0.01 after 4 h reperfusion) and the level of serum TNF (from 10.4 +/- 7.7 U/ml to 3.9 +/- 4.8 U/ml, p < 0.05); and (3) a significan positive correlation was found between the level of blood PAF or serum TNF and infarct size. The present results indicate that PAF and TNF may be important mediators involved in myocardial ischaemia and reperfusion injury, and that PAF antagonists may exert a protective effect on ischaemic or reperfused myocardium by inhibiting the interaction of PAF and TNF.     

软紫草愈伤组织的初步培养

外植体来源不同的软紫草愈伤组织产生紫草色素的能力各异。６０Ｃｏ－ｒ射线辐照处理后的Ｈ２无性系愈伤组织生长量和色素产生均属上乘。改良ＭＳ基本培养基添加１毫克／升ＫＴ,０．５毫克／升ＩＡＡ,５％（Ｗ／Ｖ）蔗糖对愈伤组织培养较为适宜。马铃薯提取液对愈伤组织生长有明显的促进作用。     

三褶脉紫菀中的新二萜甙

三褶脉紫菀（ＡｓｔｅｒａｇｅｒａｔｏｉｄｅｓＴｕｒｃｚ．）系菊科多年生草本植物,遍布全国,是民间常用的中药,有清热解毒、祛痰镇咳的功效［１,２］。化学工作者们曾从其同属植物紫菀（ＡｓｔｅｒｔａｒａｒｉｃｕｓＬ．ｆ．）中分离到紫菀酮（ｓｈｉｏｎｏｎｅ）、槲皮素（ｑｕｅｒｃｅｔｉｎ）、无羁萜（ｆｒｉｅｄｅｌｉｎ）、表无羁萜（ｅｐｉｆｒｉｅｄｅｌｉｎｅｌ）、毛叶醇（ｌａｃｈｎｏｐｈｙｌｌｏｌ）、乙酸毛叶酯（ｌａｃｈｎｏｐｈｙｌｌｏｌａｃｅｔａｔｅ）、茴香醚（ａｎｅｔｈｏｌｅ）以及紫菀三萜皂甙［２—４］…     

Direct determination of the enantiomeric purity of (R)- and (S)-2-hydroxy-4-phenylbutyric acid

The determination of enantiomeric purity of (R)- and (S)-2-hydroxy-4-phenylbutyric acid by chiral HPLC is described. Good resolution has been obtained on covalently bonded L-hydroxyproline saturated with Cu(II) ions. The method makes possible the determination of enantiomeric purity in media containing growing cells. © 1994 Wiley-Liss, Inc.