应用酶联免疫吸附试验检测马铃薯卷叶病毒

以辣根过氧化物酶标记马铃薯卷叶病毒抗体,采用双抗体夹心ELISA方法鉴定了马铃薯和洋酸浆的茎、叶、根及马铃薯块茎中的马铃薯卷叶病毒(Potato Leafroll Virus,PLRV),结果表明,对提纯的PLRV可测出的最低浓度为25ng/ml,当包被抗体浓度为40μg/ml、酶标记抗体稀释度为1/120时,可测出马铃薯茎、叶和根汁液中的PLRV,感染PLRV的洋酸浆茎、叶和根汁液的消光值,均比无病对照者高二倍以上,虽然感染PLRV的马铃薯休眠块茎维管束组织汁液的消光值高于无病毒对照,且脐部维管束组织消光值高于顶端,但测定打破休眠的感病块茎顶端维管束组织的阳性结果更为可靠和明显。     

循环血中GM-CFC的性能研究

利用造血细胞体外琼脂培养技术,比较了狗的不同来源的GM—CFC增殖、分化性能和辐射敏感性。结果表明,在正常生理条件下循环血中GM—CFC集落产率约为骨髓的1/60;细胞集落开始形成时间较骨髓晚1天,细胞集落随培养时间(前3—5天)增加而增加,其增加速率约为骨髓的20%;辐射敏感性D_0值为0.34Gy,明显低于骨髓中GM—CFC的D_0值(0.82Gy)。造血干细胞动员剂动员后血中GM—CFC数量明显增加,细胞集落增加速率约为骨髓的59%,D_0值为0.72Gy。从而为循环血干细胞移植疗效提供了实验依据。     

Removal of239Pu from mice with 3,4,3 LICAM(C) or N,N′, N″, N‴-tetra-(2,3-dihydroxybenzoyl)-spermine

Summary Male mice SAS/4 were injected i.v. with²³⁹Pu citr(IV) 0.27 µCikg^–1–9.99 kBqkg^–1. After 1 h 30 µmol kg^–1 of 3,4,3 LICAM(C), N, N, N, N-tetra-(2,3-dihydroxybenzoyl)-spermine or Na₃CaDTPA as a reference compound was given intraperitoneally. After 4 days the animals were sacrified and the Pu content in livers, kidneys, femurs and carcasses was determined by the liquid scintillation method. It was found that, as compared with the control, 3,4,3 LICAM(C) removed 83% of the Pu activity deposited in the liver, 71% of that in the femur and 79% of the Pu in the whole body. The Pu content in the kidneys exceeded the control value by about 50%. Na₃CaDTPA removed 96, 86, 40 and 72% of plutonium from the liver, kidneys, femurs and carcasses respectively.Tetra-DHB-spermine caused the excretion of 50, 57 and 39% of Pu from liver, bone and whole body respectively. The retention of Pu in the kidneys was increased to 400% of the control value.     

Nucleotide sequence of the split tRNAleu(UAA) gene from Sorghum bicolor chloroplasts

The nucleotide (nt) sequence of the split tRNAleu(UAA) gene and 328 nt of its flanking regions from sorghum chloroplasts (cp) has been determined. This gene is located in the BamHI-6 fragment in a map position very similar to that of maize. The exon of sorghum tRNAleu gene has an identical nt sequence to its counterpart in maize. Although the 450 nt of intron in sorghum is 8 nt shorter than that of maize, the nt sequence between them shows 97% homology. Like maize and broad bean, the intron from sorghum cp tRNAleu gene could be folded into a secondary structure which is similar to the postulated structure of the intron from the auto-spliceable rRNA precursor of Tetrahymena. Both introns from sorghum and maize contain open reading frames (ORFs) which are conserved at the N terminus. The putative AUG initiation codon for both ORFs is located in the stem region of a 12-bp secondary structure of highly A + T-rich sequences.     

Phylogenetic relationships in theSideritis leucantha group (Lamiaceae)

Six closely related taxa of the sect.Eusideritis of the genusSideritis (S. leucantha, S. pusilla, S. flavovirens, S. granatensis, S. biflora andS. osteoxylla) are analysed to elucidate their phylogenetic relationships and position within the sect.Eusideritis. Meiotic behaviour, karyotype features, size and fertility of pollen grains, DNA amounts and seed protein profiles are reviewed. A polyploid origin of the group (from x = 7) and the further diversification through dysploidy and chromosome repatterning is postulated.S. osteoxylla is apparently of hybrid origin.     

Dimethyl sulfoxide extraction of nystatin from mycelium

Solubility of nystatin in dimethylsulfoxide (DMSO) and its water solutions was studied. It was found that the capacity of DMSO with respect to nystatin was at least 40 times higher than that of the known extracting agents. DMSO is recommended for extraction of nystatin from dry mycelium. The optimal conditions for extraction of nystatin and its recovery from the extract phases were determined. Nystatin isolated with this method meets the specification requirements.     

Surface-active properties of antibiotics

The critical concentrations of the mycella formation of novobiocin, mithramycin, variamycin, erythromycin, oleandomycin and lincomycin were determined with two methods by changes in the isotherms of the surface tension and in the maximum absorption of rodamine due to the antibiotic concentrations. The results obtained with the two methods were comparable.     

Isolation of rat hepatocyte plasma membranes. I. Presence of the three major domains

A rat liver plasma membrane preparation was isolated and characterized both biochemically and morphologically. The isolation procedure was rapid, simple and effective in producing a membrane fraction with the following biochemical characteristics: approximately 40-fold enrichment in three plasma membrane markers, 5'-nucleotidase, alkaline phosphodiesterase I (both putative bile canalicular membrane enzymes), and the asialo-glycoprotein (ASGP) receptor (a membrane glycoprotein present along the sinusoidal front of hepatocytes); a yield of each of these plasma membrane markers that averaged approximately 16%; and minimal contamination by lysosomes, nuclei, and mitochondria, but persistent contamination by elements of the endoplasmic reticulum. Morphological analysis of the preparation revealed that all three major domains of the hepatocyte plasma membrane (sinusoidal, lateral, and bile canalicular) were present in substantial amounts. The identification of sinusoidal membrane was further confirmed when ASGP binding sites were localized predominantly to this membrane in the isolated PM using electron microscope autoradiography. By morphometry, the sinusoidal front membrane accounted for 47% of the total membrane in the preparation, whereas the lateral surface and bile canalicular membrane accounted for 6.8% and 23% respectively. This is the first report of such a large fraction of sinusoidal membrane in a liver plasma membrane preparation.     

Cloned nodulation genes of Rhizobium leguminosarum determine host-range specificity

Summary Three nodulation-deficient (nod) mutants of Rhizobium leguminosarum were isolated following insertion of the transposon Tn5 into pRL1JI, the R. leguminosarum plasmid known to carry the nodulation genes. DNA adjacent to the nod: Tn5 alleles was subcloned and used to probe a cosmid clone bank containing DNA from a Rhizobium strain carrying pRL1JI. Two cosmid clones which showed homology with the probe contained about 10 kb of DNA in common. The R. leguminosarum host-range determinants were found to be present within this 10 kb common region since either of the cosmid clones could enable a cured R. phaseoli strain to nodulate peas instead of Phaseolus beans, its normal host. Electron microscopy of nodules induced by Rhizobium strains cured of their normal symbiotic plasmid but containing either of the two cosmid clones showed bacteroid-forms surrounded by a peri-bacteroid membrane, indicating that normal infection had occurred. Thus it is clear that this 10 kb region of nodDNA carries the genes that determine host range and that relatively few bacterial genes may be involved in nodule and bacteroid development.