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31.
Relationships among the streptothricin resistance transposons Tn1825 and Tn1826 and the trimethoprim resistance transposon Tn7 总被引:9,自引:0,他引:9
The streptothricin resistance transposons Tn1825 and Tn1826 are closely related, based on physical and genetic characteristics, to the trimethoprim resistance transposon Tn7. These transposons may be considered to be members of a transposon family sharing in common the transposition functions and a basic streptomycin/spectinomycin resistance determinant but differing from one another with respect to particular additional resistance genes inserted to the left of the aadA gene. 相似文献
32.
Affinity Purification of Synenkephalin-Containing Peptides Including a Novel 23.3-Kilodalton Species 总被引:1,自引:1,他引:0
Abstract: Affinity chromatography has been used for rapid and high-yield purification of synenkephalin (proenkephalin 1 -70) containing peptides present in bovine adrenal medulla (BAM) chromaffin granular lysate. A column of CN-Br-activated Sepharose 4B coupled to synenkephalin antiserum bound synenkephalin immunoreactivity which was eluted by a stepwise gradient of 50 mM ammonium acetate containing 20% (vol/vol) acetonitrile over the pH range 7–3. Synenkephalin immunoreactivity emerged as two peaks, eluting at pH 5.5 and 4.5. Characterization of the two peaks by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and immunoblotting indicated that the pH 5.5 peak contained principally low-molecular-weight proenkephalin species (8.6 and 12.6 kilodaltons), whereas the pH 4.5 peak contained, in addition, high-molecular-weight proenkephalin species (18.2 and 23.3 kilodaltons). The 8.6- and 12.6- kilodalton species were isolated from the pH 5.5 peak by TSK gel filtration HPLC, whereas the pH 4.5 peak was further purified by passage over successive affinity columns coupled to antiserum against BAM 22P (proenkephalin 182–203) and [Met5 ]-enkephalin-Arg6 -Gly7 -Leu8 . The former column retains the 23.3-kilodalton species, whereas the latter column retains the 18.2-kilodalton species. The 23.3- kilodalton peptide represents a novel putative proenkephalin intermediate (proenkephalin-1–206), containing [Leu5 ]- enkephalin at the C-terminus. 相似文献
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35.
Robert A. Lindemann Jean A. Jenkins Robert A. Figlin Sidney H. Golub 《Cancer immunology, immunotherapy : CII》1987,25(2):153-155
Summary A new method was developed for detecting the phenotype of target binding cells (TBC) in a single-cell assay system. This methodology was evaluated during a clinical trial of recombinant interferon alfa-2a (rIFN alfa-2a) for the treatment of 10 metastatic renal cell carcinoma patients. Total TBC with K562 targets, HNK-1+ TBC, and HLA-DR+ TBC were quantitated during rIFN alfa-2a therapy. A significantly increased proportion of lymphocytes bound to target cells on day 9 of therapy bore the HNK-1 marker. This proportion subsequently declined to pretreatment levels. Total TBC paralleled the rise and fall in HNK-1+ TBC. HLA-DR+ TBC binding to targets remained constant and low throughout therapy. These findings suggest that rIFN alfa-2a early in therapy (day 9) caused the recruitment of additional HNK-1+ cells into binders. However, with continued therapy, this proportion reverts to pretreatment levels. The results of this clinical trial served to illustrate the ability of the modified single-cell assay system to detect TBC phenotype.Supported in part by Hoffman-La Roche, NIH grant CA 12582, and Jonsson Comprehensive Cancer Center grant CA 15866Dr. Figlin is a recipient of an American Cancer Society Junior Faculty Fellowship-JFCF 762-A 相似文献
36.
Shio Jean Lin Christine Figueiredo Leonard J. Sciorra Ming-liang Lee 《Human genetics》1987,76(2):173-175
Summary The induction of fragile sites on human chromosomes has been demonstrated under various conditions that cause thymidylate stress, including exposure to uridine. In this study, we examined common fragile site expression by initially exposing peripheral lymphocytes to uridine, followed by repair of the fragile sites with media containing various concentrations of thymidine. Lymphocytes were cultured in medium 199 with 2 mM uridine. At 0.5, 1, 2, 3, 8, 10, 12, and 18 h before harvest, the uridine medium was removed and replaced by medium containing thymidine at various concentrations. Our results demonstrate that the effect of uridine on chromosome fragility can be reversed by low concentrations of thymidine (2 M up to 200 M) and the rescuing effect of thymidine can be achieved if the cells were treated prior to 2–3 h before harvest. No repair was found if thymidine was added to culture within 2 h prior to harvesting, suggesting that packing of chromosomes is also an important factor in the expression and repair of fragile sites. 相似文献
37.
Catherine Digonnet-Kerhoas Gilles Gay Jean Claude Duplan Christian Dumas 《Planta》1989,179(2):165-170
During ageing of the short-lived pollen grains of Cucurbita pepo L., water loss was examined in relation to viability using biophysical (1H-nuclear magnetic resonance, NMR) and cytological methods (fluorochromatic reaction test, freezefracture and scanning electron microscopy). A semi-logarithmic representation of the pollen weight loss demonstrated the complexity of the dehydration process. A the study of proton loss using 1H-NMR indicated that two major releases water of had taken place, each with different flux rates. Pulse 1H-NMR experiments showed the occurrene of non-exponential signal decay as a function of time, indicating the existence of different fractions of water in a pollen grain sample. These fractions leave the pollen grain at different times during pollen dehydration, and one of them (that of the so-called vital water) can be related to pollen viability. The quantity of protons giving a signal during pulse 1H-NMR experiments was very low when the pollen grains were judged to be dead according to the fluorochromatic test. Freeze-fracture replicas of these dead pollen grains (less than 25% water content) showed that the plasma membrane had become detached from the intine surface; this ultrastructural feature might therefore be involved in the loss of pollen viability.Abbreviations A
initial amplitude of the NMR signal
- A2
quantity of water charcterized by T2-2
- A5
quantity of water characterized by T2–5
- FCR
fluorochromatic reaction
- NMR
nuclear magnetic resonance
- T2
transverse relaxation time
- T2-2
T2 measured with 2 ms between each pulse of radiofrequency
- T2–5
T2 measured with 5 ms between each pulse of radiofrequency 相似文献
38.
Tobacco cells are sensitive to bleomycin and phleomycin. The Tn5 and the Streptoalloteichus hindustanus (Sh) bleomycin resistance (Ble) genes conferring resistance to these antibiotics have each been inserted into two plant expression vectors. They are flanked by the nopaline synthase (nos) or the cauliflower mosaic virus (CaMV) 35S promoters on one side, and by the nos polyadenylation signal on the other. These four chimaeric genes were introduced into the binary transformation vector pGA 492, which were thereafter mobilized into Agrobacterium tumefaciens strain LBA 4404. The resulting strains were used to transform Nicotiana tabacum cv. Xanthi nc using the leaf disc transformation procedure. In all cases, phleomycin- and bleomycin-resistant tobacco plants were regenerated from transformed cells under selective conditions; however the highest frequency of rooted plants was obtained when transformation was carried out with the Sh Ble gene under the control of the 35S promoter. Phleomycin resistance was stably transmitted to sexual offspring as a dominant nuclear trait as confirmed by Southern blotting. 相似文献
39.
Catherine Manin Jean Noël Barbotin Daniel Thomas Jean Claude Lazzaroni 《Applied microbiology and biotechnology》1989,32(2):143-147
Summary In continuous cultures, alkaline phosphatase was synthesised and excreted for more than 250 h by immobilized growing cells in contrast to free cells for which the excretion decreased after 150 h of culture. This observed increase in alkaline phosphatase synthesis and excretion by immobilized cells may have resulted from growing conditions within the gel beads.Offprint requests to: C. Manin 相似文献
40.
Slim-Eric Letaíef Grard Landemore Jean Bocquet Jacques Izard 《Biology of the cell / under the auspices of the European Cell Biology Organization》1989,65(3):257-263
This paper reports that the Kurloff cell sulphated and chondroitinase AC sensitive material previously described filtered on Sepharose CL4B columns as 2 main populations with Kav of 0.25 and 0.44. Its alkaline treatment resulted in the elution of 2 peaks with Kav of 0.52 and 0.78. Their reduction in size observed after alkaline treatment and the 6-fold increase in the (35S) sulphate incorporation after addition of 0.1 mM xyloside to the incubation medium indicate that these intracellular sulphated glycosaminoglycans exist in the form of proteoglycans. They were characterized by their resistance to degradation by pronase, papain or cathepsin D, as assessed by gel filtration chromatography on Sepharose CL6B or CL4B. After the glycosaminoglycans were digested with chondroitinase AC, thin-layer chromatography analysis indicated the presence of delta di-4S and delta di-6S in a ratio of 7:1. The presence of such protease-resistant proteochondroitin sulphate in intracytoplasmic granules of both Kurloff cells and other natural killer cell types is emphasized. 相似文献