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131.
In vivo genetic engineering: homologous recombination as a tool for plasmid construction 总被引:3,自引:0,他引:3
This paper describes a novel method for creating exact DNA fusions between any two points in a plasmid carried in Bacillus subtilis. It exploits the homologous in vivo recombination between directly repeated sequences that can be established by insertion of a synthetic oligodeoxyribonucleotide. The method was used to enhance the productivity in B. subtilis of a cloned alpha-amylase (Amy)-encoding gene originating from Bacillus stearothermophilus. Thus, an exact fusion between nucleotide sequences encoding the expression signals, including the signal peptide, of a Bacillus licheniformis Amy-encoding gene and the mature Amy of B. stearothermophilus, was created. The resulting hybrid translational product was processed correctly in B. subtilis during secretion, giving rise to an Amy identical to the mature Amy secreted by B. stearothermophilus. 相似文献
132.
Summary Previous studies have indicated that rat neurofilament protein may contain an endogenous MSH-like epitope with neuroregenerative properties. The presence of such an epitope has now been studied in nerve tissue from Xenopus laevis. Western blot analyses of sciatic nerve tissue using an assortment of sequence-specific MSH/ACTH antisera revealed the presence of two major immunoreactive protein bands of 52 and 50 kDa, which contained a mid-region MSH-like epitope. Weaker staining occurred in another protein band at 135 kDa. Immunocytochemistry revealed the immunoreactivity to reside in the axis cylinders of the nerve fibers. Other antisera, recognizing other regions of MSH/ACTH produced strong staining of Xenopus intermediate lobes, but failed to stain sciatic nerves. Thus, the proteins detected have no clear relation to either Xenopus neurofilament proteins or proopiomelanocortin. 相似文献
133.
134.
Prevalence of the 281 (Gly→Glu) mutation in hepatoerythropoietic porphyria and porphyria cutanea tarda 总被引:4,自引:0,他引:4
Hubert de Verneuil Joanna Hansen Christiane Picat Bernard Grandchamp James Kushner Andrew Roberts George Elder Yves Nordmann 《Human genetics》1988,78(1):101-102
Summary The prevalence of the 281 (GlyGlu) mutation in hepatoerythropoietic porphyria (HEP) was investigated by the use of hybridization with a synthetic oligonucleotide probe. The mutation was found in HEP-affected members of two unrelated families from Spain, but was absent in two other patients from Italy and Portugal who also had HEP. Moreover, this mutation was not detected in 13 unrelated cases of familial (type II) porphyria cutanea tarda. 相似文献
135.
Dorthe Arenholt-Bindslev Børge Larsen Mohamed Abdulla Arne Jepsen 《Biological trace element research》1988,15(1):257-266
In cultures of rat tongue epithelial cells, cell proliferation following incubation with different doses of the potent tumor promoter TPA has been studied by using a stathmokinetic method counting colchicine arrested metaphases. It was demonstrated that 24 h incubation with concentrations higher than 5 ng TPA/mL medium caused inhibition, whereas below 5 ng TPA/mL medium caused stimulation of the mitotic activity reaching a maximum around 30 h from the start of the incubation period. Based on the evidence of the anticarcinogenic effect of selenium in several animal models, experiments have been performed elucidating the influence of an atoxic dose (1/1.000.000M) of selenite on the observed TPA-induced cell proliferation. Our results indicate that addition to the culture medium of an atoxic dose of selenite, not affecting the mitotic activity of control cultures, inhibits the TPA-induced stimulation of cell proliferation. 相似文献
136.
Retinoblastoma and the progression of tumor genetics 总被引:10,自引:0,他引:10
137.
Basement membranes were separated from rat glomeruli and purified by mild procedures, which led to a highly enriched basement membrane fraction. Here, the production and characterization of five monoclonal antibodies against tubular and glomerular basement membranes are described. These antibodies were analyzed immunohistochemically on frozen sections of rat, bovine, and human kidneys as well as on rat embryos. One monoclonal antibody (BM O II) exclusively recognized the glomerular basement membranes, another one (BM O VII) bound to tubular basement membranes and to Bowman's capsule. Three antibodies (BM O IV, BM M II, BM M III) recognized their antigens in both glomerular and tubular basement membranes as well as in mesangial cells. The BM O II antibody showed a stringent species specificity and bound only to glomerular basement membranes of the rat. The other four antibodies cross-reacted with human and bovine glomerular basement membrane and mesangial antigens; they also bound to other tissues in the developing rat embryo. Antibody binding to specific purified components of the basement membranes such as collagen type IV, laminin, heparan sulphate proteoglycan, and fibronectin was investigated by enzyme-linked immunosorbent assay (ELISA). None of these antibodies reacted with any of these known basement membrane components, indicating that the antibodies may serve as useful tools in future investigations of so far unidentified components of basement membranes. 相似文献
138.
Effects and interactions of varying CaSO4 and NaCl levels on growth and nitrogen fixation ofLeucaena leucocephala K8 were examined. Leucaena was grown in nutrient solution at four levels of CaSO4 (0.5, 1.0, 2.5 and 5.0 mM) and NaCl (1, 25, 50 and 100 mM) in randomized blocks with five replications. While NaCl significantly reduced plant growth, additions of CaSO4 increased plant height, leaf number, and biomass of salt treated plants. For the nonsaline treatments, high CaSO4 levels slightly depressed growth, which contradicts suggestions that Leucaena has a high calcium requirement. A significant
calcium/sodium interaction was not seen for nodule number or weight. Nodule number was significantly depressed by 100 mM NaCl and nodule weight of the salt stressed plants significantly increased as CaSO4 concentration increased from 0.5 to 2.5 mM. Effects of NaCl and CaSO4 on nitrogen content of plant parts were inconclusive. The promotion of Leucaena salinity tolerance by addition of CaSO4 may be attributed to the effect of calcium in maintaing the selective permeability of membranes. 相似文献
139.
Lise Stengård Hansen 《BioControl》1988,33(1):33-42
The phytoseiid miteAmblyseius barkeri (Hughes) (=Amblyseius mckenziei Sch. & Pr.) was used for biological control ofThrips tabaci Lind. in 7 commercial glasshouses with cucumber (a total of 5780 m2). Predatory mites were introduced 3–4 times in densities ranging from 40 to 300/m2 at each release. In 6 of the 7 glasshouses, control of thrips was satisfactory throughout the growing season. Thrips densities
were kept below 15 individuals per leaf. In 1 glasshouse, thrips damage was seen on the fruits at densities of 25 thrips per
leaf, but the thrips population was quickly reduced and remained at low densities for the next 3 months.
相似文献
140.
Characterization of the Antirrhinum floral homeotic MADS-box gene deficiens: evidence for DNA binding and autoregulation of its persistent expression throughout flower development. 总被引:26,自引:9,他引:17
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Z Schwarz-Sommer I Hue P Huijser P J Flor R Hansen F Tetens W E Lnnig H Saedler H Sommer 《The EMBO journal》1992,11(1):251-263