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91.
Isolation of a recombinant lambda phage carrying nusA and surrounding region of the Escherichia coli K-12 chromosome 总被引:5,自引:0,他引:5
Summary A recombinant bacteriophage lambda, argG-6, has been isolated which carries the argG gene and neighbouring loci on an EcoRI-generated 15.5 Kb DNA fragment from the Escherichia coli chromosome. The locations of the argG, nusA and pnp genes on the 15.5 Kb DNA fragment have been determined. In the case of nusA, a Tn5 insertion and sub-cloning of restriction fragments were used to locate the gene. The gene products of nusA and pnp have been identified on one- and two-dimensional polyacrylamide gels. The clockwise gene order was found to be argG-nusA-pnp. 相似文献
92.
W. Scott Ramsey Eugene D. Nowlan Lynn B. Simpson 《Applied microbiology and biotechnology》1980,9(3):217-226
Summary The resolution of bacterial mixtures by free flow electrophoresis (FFE) was not affected by the position of the microbes on the growth curve and approximately 70% of the individual cells applied were recovered as viable cells. The dependence of bacterial electrophoretic mobility on the pH, salt concentration, and viscosity of the electrolyte was determined. Suspending media and running electrolyte were developed which allowed collection of samples of>99% purity within two minutes of introduction of a mixture of Escherichia coli and Staphylococcus aureus. Most bacterial strains migrated in a single band, although some migrated in more than one band. Escherichia coli was resolved from each of 10 different species. The considerable variation in mobility found in 21 different E. coli strains, however, appears to preclude use of FFE as a method of species identification. 相似文献
93.
Reduction of 3-ketosucrose (1) with sodium borohydride gave mainly α-d-allopyranosyl β-d-fructofuranoside (2) characterized as its octabenzoate. Using sodium borodeuteride, [3-2H]allo-sucrose (5) and [3-2H]sucrose (6) were obtained in the ratio 12:1. The mixture was fractionated on Dowex-50 X8 resin (Ca2+ form), and the [3-2H] derivatives were isolated as their octa-acetates. Inspection of the 13C-n.m.r. spectra of 5 and 6 enabled the C-3 signals to be assigned. allo-Sucrose (2) was more readily obtained by oxidation of sucrose with dimethyl sulphoxide-acetic anhydride followed by reduction with sodium borohydride and fractionation on Dowex-50 X8 (Ca2+) resin. Tritylation of 2 followed by acetylation gave, after chromatography, the 6,1′,6′-tritrityl ether (9, 10%), the 6,6′-ditrityl ether (10, 26%), and a mixture of monotrityl ethers (20%). Hydrogenolysis of 9 and 10 gave the penta-acetate and hexa-acetate, respectively, with no detectable migration of AcO-4. Treatment of 2 with sulphuryl chloride at -50° gave the 6,6′-dichloride. 相似文献
94.
Development of two cloned epithelial cell lines from normal adult mouse and rat ventral prostates 总被引:1,自引:0,他引:1
Yoshinobu Kubota Eugene B. Gehly Karl H. Link Charles Heidelberger 《In vitro cellular & developmental biology. Plant》1981,17(11):965-978
Summary Two epithelial cell lines were established, one from adult C3H mouse and one from adult Fischer rat ventral prostate. These
cell lines were obtained from explant cultures, using Ham's F12 medium supplemented with HEPES, insulin, testosterone, hydrocortisone,
epidermal growth factor, and 7.5% fetal bovine serum. A low concentration of trypsin and EDTA in Ca++-and Mg++-free phosphate buffer was used for passaging the cells. The rat cell line was established following implantation of prostate
tissue in nude mice. These cell lines stained positively for acid phosphatase and were dependent upon epidermal growth factor
for growth. Morphological studies, including electron microscopy, revealed a highly characteristic epithelial morphology of
both cell lines. These cell lines have hypotetraploid chromosome numbers and are capable of metabolizing benzo(a)pyrene. We propose the application of these cells as models for the study of prostate carcinogenesis.
This work was supported in part by Grant CA-21, 746, and by the Electron Microscope Core Facility on Grant CA-14,089, from
the National Cancer Institute, National Institutes of Health, Bethesda, MD. 相似文献
95.
Arthur D. Schwabe Paul I. Terasaki Eugene V. Barnett Mary C. Territo James R. Klinenberg Robert S. Peters 《The Western journal of medicine》1977,127(1):15-23
The success of colchicine therapy in the management of familial Mediterranean fever has provided new direction to investigations into the pathogenesis of this disease. Examination of HLA antigen frequencies in 53 patients with familial Mediterranean fever and appropriate controls, as well as various immunologic studies have yielded no significant differences. However, B lymphocyte typing and assays for immune complexes, lymphokines and prostaglandins may be of potential interest. Preliminary studies indicate that leukocytes of patients with familial Mediterranean fever release increased amounts of lysozyme (P<0.01), when subjected to high temperatures, and of both lysozyme and myeloperoxidase at low osmotic concentrations. The known and potential effects of colchicine on leukocyte and cellular metabolism, and the current status of colchicine prophylaxis are reviewed. In patients receiving an optimum colchicine dose of 1.5 to 1.8 mg per day, side effects have been minimal and the frequency of attacks has been decreased significantly. 相似文献
96.
Synopsis The interaction of fluctuating water level and the Long Point topography is discussed with regard to the formation of lake-shore lagoons and their subsequent invasion by fishes. The species composition of fish communities in these lagoons was determined by 12 collections from lagoons (23 m2 to 25 ha) which yielded 33 fish species. The relationship of the number of fish species to lagoon area was lognormal; that is, with increasing lagoon area the number of species rose rapidly at first but soon decreased sharply, probably limited by the number of species capable of surviving in the habitat. The marked effect of area on species number in small lagoons is considered in the context of a hypothetical seasonal pattern of occasional invasion and continuous extinction.A sequence of reproductive guilds was found. In beach lagoons psammophils and lithophils were dominant. In a large vegetated lagoon in the interior phytophils and speleophils were dominant. This sequence was paralleled by an increase in the proportion of guarding and nesting species in the communities. The sequence was disrupted in the small interior lagoons where adaptations for survival were more important than reproductive strategy. 相似文献
97.
98.
Ruby Celeste Eugene Ackerman Laël C. Gatewood Clayton Reynolds George D. Molnar 《Bulletin of mathematical biology》1978,40(1):59-77
Mathematical models afford a procedure of unifying concepts and hypotheses by expressing quantitative relationships between
observables. The model presented indicates the roles of both insulin and glucagon as regulators of blood glucose, albeit in
different ranges of the blood glucose concentrations. Insulin secretion is induced during hyperglycemia, while glucagon secretion
results during hypoglycemia. These are demonstrated by simulations of a mathematical model conformed to data from the oral
glucose tolerance test and the insulin infusion test in normal control subjects and stable and unstable diabetic patients.
The model studies suggest the parameters could prove of value in quantifying the diabetic condition by indicating the degree
of instability.
Presented at the Society for Mathematical Biology Meeting, University of Pennsylvania, Philadelphia, August 19–21, 1976. 相似文献
99.
The rabbit geneLpq, which codes for a low-density serum lipoprotein2, is linked (34.6 ± 5.3 centimorgans) to the Ig kappa light-chain gene (Ab). There is no evidence thatLpq is linked to another gene,Prt, that was previously found to be linked to theAb gene. This suggests that the gene order for the three genes isPrt- Ab- Lpq.
Abbreviations used in this paper Ig
immunoglobulin
-
a
the heavy-chain variable-region geneAa
-
b
the kappa light-chain geneAb
-
q
the low-density serum lipoprotein geneLpq 相似文献
100.
The partition behavior of cells in dextran-poly(ethylene glycol) aqueous phases (i.e., the cells' relative affinity for the top or bottom phase or their adsorption at the interface) is greatly dependent on the polymer concentrations and ionic composition and concentration. Appropriate selection of phase system composition permits detection of differences in either charge-associated or lipid-related surface properties. We have now developed a method that can reveal differences by partitioning that fall within experimental error if one were to compare countercurrent distribution (CCD) curves of two closely related cell populations run separately. One cell population is isotopically labeled in vitro (e.g., with51Cr-chromate) and is mixed with an excess of the unlabeled cell population with which it is to be compared. The mixture is subjected to CCD and the relative specific radio-activities are determined through the distribution. As control we also examine a mixture of labeled cells and unlabeled cells of the same population. The feasibility of this method was established by use of cell mixtures the relative partition coefficients of which were known. The procedure was then used to test for human erythrocyte subpopulations51Cr-chromate-labeled human young or old red blood cells were mixed with unfractionated erythrocytes and subjected to CCD in a phase system reflecting charge-associated properties. It was found that older cells had a high, young cells (probably only reticulocytes) a low partition coefficient. Because of the small differences involved these results were not previously obtained. It was further determined, by repartitioning51Cr-labeled cells from the left or right ends of a CCD of human red blood cells admixed to unlabeled unfractionated erythrocytes, that a subpopulation with higher partition coefficient exists (probably constituting the old red cells). These experiments serve to illustrate (a) that human red blood cells, contrary to a previous report, can be subfractionated by partitioning and (b) the usefulness of this new method in detecting smaller surface differences between closely related cell populations than was heretofore possible by partitioning alone. 相似文献