Gene fusion vectors based on the gene for staphylococcal protein A

Two plasmid vectors, containing the gene coding for staphylococcal protein A and adapted for gene fusion, have been constructed. These vectors will allow fusion of any gene to the protein A gene, thus giving hybrid proteins which can be purified, in a one-step procedure, by IgG affinity chromatography. As an example of the practical use of such vectors, the protein A gene has been fused to the lacZ gene of Escherichia coli. E. coli strains containing such plasmids produce hybrid proteins with both IgG binding and β-galactosidase activities. The hybrid protein(s) can be immobilized on IgG-Sepharose by its protein A moiety with high efficiency without losing its enzymatic activity and they can be eluted from the column by competitive elution with pure protein A. The fused protein(s) also binds to IgG-coated microtiter wells which means that the in vivo product can be used as an enzyme conjugate in ELISA tests.     

Restriction map of Chinese hamster mitochondrial DNA containing replication coordinates: comparison with Syrian hamster mitochondrial genome

A precise physical map, containing the structurally and operationally defined D-loop origin, terminal region, and direction of heavy-strand replication, has been constructed for mitochondrial DNA (mtDNA) from ovary (CHO-KI) and lung cells of Chinese hamster (Cricetulus griseus 2 N = 22), and compared with our previously established genome coordinates for mtDNA from Syrian hamster ( Mesocricetus auratus 2 N = 44). All four HpaI sites in Cricetulus are conserved in Mesocricetus (8 sites). Extensive variation exists for hexanucleotides cleaved by EcoRI HindIII PstI. KpnI and BamHI. Sequence divergence between Chinese and Syrian hamster mtDNAs, as reflected from analysis of the mapped recognition sites for these six endonucleases, is estimated as 5–9% base substitutions. mtDNAs from both hamster and several other mammalian species contain a commonly conserved HpaI site in the region of light strand initiation.     

Isolation and characterization of a fragment of rat thyroglobulin gene

A rat genomic library was screened for thyroglobulin gene clones with recombinant plasmids containing rat thyroglobulin complementary DNA inserts. Two identical recombinant phages were found. A map of the inserted genomic sequence established by restriction and blotting experiments, and electronic microscopy revealed that this fraction of the gene was extensively split. Exons were ≤ 200 base pair long while the introns represented 93% of the insert. A fragment subcloned in plasmid pBR 322 was shown to contain repetitive sequences when used in Southern blot experiments with rat total genomic DNA.     

Nucleosomal distribution of thymine photodimers following far- and near-ultraviolet irradiation

The nucleosomal distribution of cis-syn cyclobutyl-type thymine photodimers was determined in normal human skin fibroblasts following irradiation with low doses of far-ultraviolet light at 254 nm and nearultraviolet light at 313 nm. The thymine photodimer concentrations were determined by high pressure liquid chromatography in acid hydrolysates of total cellular DNA and of nucleosomal core- and chromatosomal-DNA. The lesion concentrations in linker-DNA were calculated from these data. While thymine photodimers were distributed uniformely following 254 nm irradiation they were enriched by a factor of 2.4 – 4.2 in nucleosomal linker DNA after exposure to 313 nm light.     

应用组织培养方法选育耐盐碱水稻新品种

本文报道了应用组织培养方法,选育耐盐碱水稻.作法是将去壳的水稻种子经常规消毒接种在脱分化培养基诱导形成愈伤组织,继代一次,转移到加压培养基(MS+2.4-D2mg/L+NaCl1%+NaHCO_30.5%),处理20天,再转移到分化培养基,分化并培育出组培水稻119份,简称为D水稻.D水稻又经过盐碱地的实际种植,大批D水稻被田间粗筛而淘汰掉,保存下20份从形态表现和耐盐碱性较好的材料.然后对20份D水稻的脯氨酸含量和叶绿素含量进行测定分析并与其耐盐碱性进行比较,把各项指标综合起来鉴定其耐盐碱性,最终筛选出7价为耐盐碱性较强的水稻新品系.其中647—4表现为最耐盐碱、抗病、高产的水稻.     

Racemization of the aqua-{N-salicylidene-(S)-alaninato}copper(II) by reaction with potassium cyanate

Copper(II) N-salicylidene-(S)-alaninate trihydrate reacting as the S-enantiomeric parent compound with KOCN in hot diluted methanol yielded by slow crystallisation from the cooled reaction mixture (in the course of 1 day) the racemic product K[Cu{sal-(RS)-ala}(NCO)]. The parameters of the axial type EPR spectrum in X-band region and the LF band position in the electronic spectrum are typical of an axially distorted square pyramidal coordination of the Cu(II) atom in this complex. The spectral properties of the complex cuprate prepared and its basal crystallographic data are consistent with those of the earlier studied¹⁵ K₂[Cu₂{sal-(RS)-ala}₂(μ-NCO)₂] synthetized by using [Cu{sal-(RS)-ala}(H₂O)].H₂O as the racemic parent complex in the reaction mixture with KOCN.     

Restriction fragment maps of the genome of Bacillus subtilis bacteriophage SPβ

Six different restriction endonucleases were used to generate restriction fragment maps of the genome of the temperate Bacillus subtilis phage SPβ. AvaI and SalI each had six target sites in the phage DNA, AvaII had three, BamHI had seven, PstI had twenty, and SacI had sixteen. Restriction analysis and heteroduplex analysis were used to locate a 10-kb region of DNA that is deleted in the clear-plaque mutant, spβci. Thedeletion lay approx. 50 kb from the left end of the 126-kb phage genome.